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The algorithm samples the relative velocity directly, thereby avoiding a potentially inefficient rejection step based on the ratio of cross sections.
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A novel velocity navigator with Kalman filter postprocessing in real time significantly improves the temperature accuracy over non-triggered acquisitions and suggests being comparable to a breath-held acquisition. The proposed technique might be clinically applied for monitoring of thermal ablations in abdominal organs. It is unknown whether a bio-behavioral index of distress intolerance, breath-holding duration, is acutely influenced increased or decreased by cannabis.
Such information may further inform understanding of the expression of psychological or physiological distress post-cannabis use. This within-subjects study examined whether smoked marijuana with 2. Controlling for baseline breath-holding duration and participant sex, THC produced significantly lower breath-holding durations relative to placebo.
There was a significant interaction of drug administration x frequency of cannabis use, such that THC decreased breath-holding time among less frequent but not among more frequent users.
Findings indicate that cannabis may be exacerbating distress intolerance via breath-holding duration. Objective measures of distress intolerance are sensitive to contextual factors such as acute drug intoxication, and may inform the link between cannabis use and the expression of psychological distress.
Depth- encoded dual beam phase-resolved Doppler OCT for Doppler-angle-independent flow velocity measurement. Phase-resolved Doppler optical coherence tomography PR-D-OCT is a functional OCT imaging technique that can provide high-speed and high-resolution depth-resolved measurement on flow in biological materials.
In this paper, we proposed a novel dual-beam PR-D-OCT method to measure absolute flow velocity without separate measurement on the projection angle.
Two parallel light beams are created in sample arm and focused into the sample at two different incident angles. The images produced by these two beams are encoded to different depths in single B-scan. Then the Doppler signals picked up by the two beams together with the incident angle difference can be used to calculate the absolute velocity.
We validated our approach in vitro on an artificial flow phantom with our home-built nm swept source OCT. Experimental results demonstrated that our method can provide an accurate measurement of absolute flow velocity with independency on the projection angle.
It has been widely believed that tissue nitrogen uptake from the lungs during breath-hold diving would be insufficient to cause decompression stress in humans. With competitive free diving, however, diving depths have been ever increasing over the past decades.
A case is presented of a competitive free-diving athlete who suffered stroke-like symptoms after surfacing from his last dive of a series of 3 deep breath-hold dives. A literature and Web search was performed to screen for similar cases of subjects with serious neurological symptoms after deep breath-hold dives.
A previously healthy y-old athlete experienced right-sided motor weakness and difficulty speaking immediately after surfacing from a breathhold dive to a depth of m. He had performed 2 preceding breath-hold dives to that depth with surface intervals of only 15 min.
The presentation of symptoms and neuroimaging findings supported a clinical diagnosis of stroke. Three more cases of neurological insults were retrieved by literature and Web search; in all cases the athletes presented with stroke-like symptoms after single breath-hold dives of depths exceeding m.
Two of these cases only had a short delay to recompression treatment and completely recovered from the insult. This report highlights the possibility of neurological insult, eg, stroke, due to cerebral arterial gas embolism as a consequence of decompression stress after deep breath-hold dives.
Thus, stroke as a clinical presentation of cerebral arterial gas embolism should be considered another risk of extreme breath-hold diving. Objective Breath-holding spells are known as benign attacks, frequencies of which decrease by the development of the autonomic nervous system. The present study aims to compare the electrocardiographic repolarization in children with breath-holding spells. Methods In this study, QT dispersion, QTc dispersion, T peak to T end dispersion, and P wave dispersion of the twelve-lead surface electrocardiography of fifty children who had breath-holding spells were measured and compared with normal children from April to August QTc dispersion was increased in the patients with breath-holding spells Conclusion QTc dispersion was significantly increased in the patients with breath-holding spells compared to normal children and this is a sign of cardiac repolarization abnormality as well as the increased risk of cardiac arrhythmia in patients with breath-holding spells.
Sequence optimization to reduce velocity offsets in cardiovascular magnetic resonance volume flow quantification – A multi-vendor study.
Purpose Eddy current induced velocity offsets are of concern for accuracy in cardiovascular magnetic resonance CMR volume flow quantification. However, currently known theoretical aspects of eddy current behavior have not led to effective guidelines for the optimization of flow quantification sequences. This study is aimed at identifying correlations between protocol parameters and the resulting velocity error in clinical CMR flow measurements in a multi-vendor study.
Methods Nine 1. Measurements were performed on a large stationary phantom. Starting from a clinical breath-hold flow protocol, several protocol parameters were varied. Acquisitions were made in three clinically relevant orientations. Additionally, a time delay between the bipolar gradient and read-out, asymmetric versus symmetric velocity encoding , and gradient amplitude and slew rate were studied in adapted sequences as exploratory measurements beyond the protocol.
Image analysis determined the worst-case offset for a typical great-vessel flow measurement. Results The results showed a great variation in offset behavior among scanners standard deviation among samples of 0. Considering the absolute values, none of the tested protocol settings consistently reduced the velocity offsets below the critical level of 0.
Using multilevel linear model analysis, oblique aortic and pulmonary slices showed systematic higher offsets than the transverse aortic slices oblique aortic 0.
The exploratory measurements beyond the protocol yielded some new leads for further sequence development towards reduction of velocity offsets; however those protocols were not always compatible with the time-constraints of breath-hold. Comparison of breathhold , navigator-triggered, and free-breathing diffusion-weighted MRI for focal hepatic lesions. To compare the breathhold , navigator-triggered, and free-breathing techniques in diffusion-weighted magnetic resonance imaging MRI for the evaluation of focal liver lesions on a 3.
Fifty-two patients 36 men, 16 women; mean age, A total of 74 lesions 50 malignant, 24 benign were evaluated. The detection sensitivity and characterization accuracy were also compared. The ADC values of the liver and focal lesions measured using the three DWI techniques were not significantly different and showed good correlation.
For lesion detection and characterization, there were no significant differences between breathhold and non- breathhold DWI. Both breathhold and non- breathhold DWI are comparable for the detection or characterization of focal liver lesions at 3. In addition, although free-breathing and navigator-triggered DWI sequences show similar performance for 3.
Hyperbaric nitrogen prolongs breath-holding time in humans. Either an increase in PaCO 2 or a decrease in PaO 2 , can affect respiratory stimulation through respiratory centers, thus influencing breath-holding time BHT. This study was designed to determine whether and how hyperbaric air could influence BHT in comparison with hyperbaric oxygen in humans.
We studied 36 healthy volunteers in a multiplace hyperbaric chamber. BHT, pulse oximeter, and transcutaneous carbon dioxide tension were measured at 1 and 2. The prolongation of BHT in hyperbaric air is significantly greater than that in hyperbaric oxygen. Breath-holding time is significantly prolonged in hyperbaric air than it is in hyperbaric oxygen.
The mechanism involves the anesthetic effect of nitrogen suppressing the suffocating feeling during breath-holding. To present our clinical workflow of incorporating AlignRT for left breast deep inspiration breath-hold treatments and the dosimetric considerations with the deep inspiration breath-hold protocol. Patients with stage I to III left-sided breast cancer who underwent lumpectomy or mastectomy were considered candidates for deep inspiration breath-hold technique for their external beam radiation therapy.
Treatment plans were created on both free-breathing and deep inspiration breath-hold computed tomography for each patient to determine whether deep inspiration breath-hold was beneficial based on dosimetric comparison.
The AlignRT system was used for patient setup and monitoring. Dosimetric measurements and their correlation with chest wall excursion and increase in left lung volume were studied for free-breathing and deep inspiration breath-hold plans.
Deep inspiration breath-hold plans had significantly increased chest wall excursion when compared with free breathing. This change in geometry resulted in reduced mean and maximum heart dose but did not impact lung V 20 or mean dose. The correlation between chest wall excursion and absolute reduction in heart or lung dose was found to be nonsignificant, but correlation between left lung volume and heart dose showed a linear association.
It was also identified that higher levels of chest wall excursion may paradoxically increase heart or lung dose. Reduction in heart dose can be achieved for many left-sided breast and chest wall patients using deep inspiration breath-hold. Chest wall excursion as well as left lung volume did not correlate with reduction in heart dose, and it remains to be determined what metric will provide the most optimal and reliable dosimetric advantage.
Effects of depth and chest volume on cardiac function during breath-hold diving. Cardiac response to breath-hold diving in human beings is primarily characterized by the reduction of both heart rate and stroke volume. We hypothesized that underwater re-expansion of the chest would release heart constriction and normalize cardiac function. To this aim, 10 healthy male subjects age During the same session, all subjects were also studied at surface full-body immersion and at 5-m depth in order to better characterize the relationship of echo-Doppler pattern with depth.
In conclusion the diving response, already evident during shallow diving 5 m did not progress during deeper dives 10 m. The rapid improvement in systolic and diastolic function observed after lung volume expansion is congruous with the idea of a constrictive effect on the heart exerted by chest squeeze.
Breath-holds are a readily accessible method for producing the required arterial CO2 increases but their implementation into clinical studies is limited by concerns that patients will demonstrate highly variable performance of breath-hold challenges. This study assesses the repeatability of CVR measurements despite poor task performance, to determine if and how robust results could be achieved with breath-holds in patients.
Twelve healthy volunteers were scanned at 3 T. Six functional scans were acquired, each consisting of 6 breath-hold challenges 10, 15, or 20 s duration interleaved with periods of paced breathing.
These scans simulated the varying breath-hold consistency and ability levels that may occur in patient data. Uniform ramps, time-scaled ramps, and end-tidal CO2 data were used as regressors in a general linear model in order to measure CVR at the grey matter, regional, and voxelwise level.
The intraclass correlation coefficient ICC quantified the repeatability of the CVR measurement for each breath-hold regressor type and scale of interest across the variable task performances. The ramp regressors did not fully account for variability in breath-hold performance and did not achieve acceptable repeatability ICC 0. Further analysis of intra-subject CVR variability across the brain ICCspatial and voxelwise correlation supported the use of end-tidal CO2 data to extract robust whole-brain CVR maps, despite variability in breath-hold performance.
We conclude that the incorporation of end-tidal CO2 monitoring into scanning enables robust, repeatable. Do elite breath-hold divers suffer from mild short-term memory impairments? Repeated apneas are associated with severe hypoxemia that may ultimately lead to loss of consciousness in some breath-hold divers. Despite increasing number of practitioners, the relationship between apnea-induced hypoxia and neurocognitive functions is still poorly understood in the sport of free diving.
To shed light onto this phenomenon, we examined the impact of long-term breath-hold diving training on attentional processing, short-term memory, and long-term mnesic and executive functions.
Thirty-six men matched for age, height, and weight were separated into the following 3 groups: i 12 elite breath-hold divers EBHD , mean static apnea best time s, months mean apnea experience; ii 12 novice breath-hold divers, mean best time s, 8.
We used breath-holding during inspiration as a model to study the effect of pulmonary stretch on sympathetic nerve activity. Prolonged dry apnoea: effects on brain activity and physiological functions in breath-hold divers and non-divers. The aim of the study was to investigate the effects of voluntary breath-holding on brain activity and physiological functions.
We hypothesised that prolonged apnoea would trigger cerebral hypoxia, resulting in a decrease of brain performance; and the apnoea’s effects would be more pronounced in breath-hold divers. Trained breath-hold divers and non-divers performed maximal dry breath-holdings.
Lung volume, alveolar partial pressures of O2 and CO2, attention and anxiety levels were estimated. Heart rate, blood pressure, arterial blood oxygenation, brain tissue oxygenation, EEG, and DC potential were monitored continuously during breath-holding. There were a few significant changes in electrical brain activity caused by prolonged apnoea. Brain tissue oxygenation index and DC potential were relatively stable up to the end of the apnoea in breath-hold divers and non-divers.
We also did not observe any decrease of attention level or speed of processing immediately after breath-holding. Interestingly, trained breath-hold divers had some peculiarities in EEG activity at resting state before any breath-holding : non-spindled, sharpened alpha rhythm; slowed-down alpha with the frequency nearer to the theta band; and untypical spatial pattern of alpha activity.
Our findings contradicted the primary hypothesis. Apnoea up to 5 min does not lead to notable cerebral hypoxia or a decrease of brain performance in either breath-hold divers or non-divers.
It seems to be the result of the compensatory mechanisms similar to the diving response aimed at centralising blood circulation and reducing peripheral O2 uptake. Adaptive changes during apnoea are much more prominent in trained breath-hold divers. Optimization of single shot 3D breath-hold non-enhanced MR angiography of the renal arteries.
Cardiac and navigator-gated, inversion-prepared non-enhanced magnetic resonance angiography techniques can accurately depict the renal arteries without the need for contrast administration. However, the scan time and effectiveness of navigator-gated techniques depend on the subject respiratory pattern, which at times results in excessively prolonged scan times or suboptimal image quality.
A single-shot 3D magnetization-prepared steady-state free precession technique was implemented to allow the full extent of the renal arteries to be depicted within a single breath-hold.
Technical optimization of the breath-hold technique was performed with fourteen healthy volunteers. An alternative magnetization preparation scheme was tested to maximize inflow signal. Quantitative and qualitative comparisons were made between the breath-hold technique and the clinically accepted navigator-gated technique in both volunteers and patients on a 1.
The breath-hold technique provided an average of seven fold reduction in imaging time, without significant loss of image quality. Comparable single-to-noise and contrast-to-noise ratios of intra- and extra-renal arteries were found between the breath-hold and the navigator-gated techniques in volunteers.
Furthermore, the breath-hold technique demonstrated good image quality for diagnostic purposes in a small number of patients in a pilot study. The single-shot, breath-hold technique offers an alternative to navigator-gated methods for non-enhanced renal magnetic resonance angiography.
The initial results suggest a potential supplementary clinical role for the breath-hold technique in the evaluation of suspected renal artery diseases. Glide-Hurst, Carri K. Purpose: To evaluate intra- and interfraction variability of tumor and lung volume and position using a hybrid active breath-hold gating technique. Methods and Materials: A total of repeat normal inspiration active breath-hold CTs were acquired weekly during radiotherapy for 9 lung cancer patients scans per patient. A physician delineated the gross tumor volume GTV , lungs, and spinal cord on the first breath-hold CT, and contours were propagated semiautomatically.
Intra- and interfraction variability of tumor and lung position and volume were evaluated. Tumor centroid and border variability were quantified. Results: On average, intrafraction variability of lung and GTV centroidmore » position was 0.
Increases in free-breathing tidal volume were associated with increases in breath-hold ipsilateral lung volume p breath-hold technique was reproducible within 2 mm during each fraction. Interfraction variability of GTV position and shape was substantial because of tumor volume and breath-hold lung volume change during therapy. These results support the feasibility of a hybrid breath-hold gating technique and suggest that online image guidance would be beneficial. Underwater study of arterial blood pressure in breath-hold divers.
Knowledge regarding arterial blood pressure ABP values during breath-hold diving is scanty. It derives from a few reports of measurements performed at the water’s surface, showing slight or no increase in ABP, and from a single study of two simulated deep breath-hold dives in a hyperbaric chamber.
Simulated dives showed an increase in ABP to values considered life threatening by standard clinical criteria. For the first time, using a novel noninvasive subaquatic sphygmomanometer, we successfully measured ABP in 10 healthy elite breath-hold divers at a depth of 10 m of freshwater mfw. ABP was measured in dry conditions, at the surface head-out immersion , and twice at a depth of 10 mfw. Underwater measurements of ABP were obtained in all subjects. Each measurement lasted s and was accomplished without any complications or diver discomfort.
No significant statistical differences were found when blood pressure measurements at the water surface were compared with breath-hold diving conditions at a depth of 10 mfw. However, our results cannot be extended over environmental conditions different from those of the present study. Harouni, Ahmed A. Purpose An external driver-free MRI method for assessment of liver fibrosis offers a promising non-invasive tool for diagnosis and monitoring of liver disease.
However, MR tagging requires multiple breath-hold acquisitions and substantial post-processing. Additionally, a new method is introduced to measure heart-induced shear wave velocity SWV inside the liver. Methods Phantom and in-vivo experiments 11 healthy subjects, and 11 patients with liver fibrosis were conducted.
Reproducibility experiments were performed in seven healthy subjects. Results Peak liver strain Sp significantly decreased in fibrotic liver compared healthy liver 6.
The two measures significantly separate healthy subjects from patients with fibrotic liver. Purpose: To evaluate the feasibility of 3D single breath-hold late gadolinium enhancement LGE of the left ventricle LV using supplemental oxygen and hyperventilation and compressed-sensing acceleration. Semi-quantitative grading of overall image quality, motion artifact, myocardial nulling, and diagnostic value was performed by consensus of two blinded observers.
Velocity encoding with the slice select refocusing gradient for faster imaging and reduced chemical shift-induced phase errors. To investigate a novel phase-contrast MRI velocity-encoding technique for faster imaging and reduced chemical shift-induced phase errors.
Velocity encoding with the slice select refocusing gradient achieves the target gradient moment by time shifting the refocusing gradient, which enables the use of the minimum in-phase echo time TE for faster imaging and reduced chemical shift-induced phase errors.
Improved net forward flow agreement was measured across all vessels for slice select refocused gradient compared to flow compensated and flow encoded : aAo vs. To evaluate the feasibility of three-dimensional 3D single breath-hold late gadolinium enhancement LGE of the left ventricle LV using supplemental oxygen and hyperventilation and compressed-sensing acceleration. Semiquantitative grading of overall image quality, motion artifact, myocardial nulling, and diagnostic value was performed by consensus of two blinded observers.
Dosimetric comparison of moderate deep inspiration breath-hold and free-breathing intensity-modulated radiotherapy for left-sided breast cancer. This study determined the dosimetric comparison of moderate deep inspiration breath-hold using active breathing control and free-breathing intensity-modulated radiotherapy IMRT after breast-conserving surgery for left-sided breast cancer. Thirty-one patients were enrolled. One free breathe and two moderate deep inspiration breath-hold images were obtained.
A field-in-field-IMRT free-breathing plan and two field-in-field-IMRT moderate deep inspiration breath-holding plans were compared in the dosimetry to target volume coverage of the glandular breast tissue and organs at risks for each patient. The breath-holding time under moderate deep inspiration extended significantly after breathing training P breath-holding in the target volume coverage.
The volume of the ipsilateral lung in the free-breathing technique were significantly smaller than the moderate deep inspiration breath-holding techniques P breath-holding plans. The dose to ipsilateral lung, coronary artery and heart in the field-in-field-IMRT were significantly lower for the free-breathing plan than for the two moderate deep inspiration breath-holding plans all P breath-holding plans.
The whole-breast field-in-field-IMRT under moderate deep inspiration breath-hold with active breathing control after breast-conserving surgery in left-sided breast cancer can reduce the irradiation volume and dose to organs at risks.
There are no significant differences between various moderate deep inspiration breath-holding states in the dosimetry of irradiation to the field-in-field-IMRT target volume. Asystole and increased serum myoglobin levels associated with ‘packing blackout’ in a competitive breath-hold diver. Many competitive breath-hold divers use ‘glossopharyngeal insufflation’, also called ‘lung packing’, to overfill their lungs above normal total lung capacity.
This increases intrathoracic pressure, decreases venous return, compromises cardiac pumping, and reduces arterial blood pressure, possibly resulting in a syncope breath-hold divers call ‘packing blackout’.
We report a case with a breath-hold diver who inadvertently experienced a packing blackout. During the incident, an electrocardiogram ECG and blood pressure were recorded, and blood samples for determinations of biomarkers of cardiac muscle perturbation creatine kinase-MB isoenzyme CK-MB , cardiac troponin-T TnT , and myoglobin were collected. The ECG revealed short periods of asystole during the period of ‘packing blackout’, simultaneous with pronounced reductions in systolic, diastolic, and pulse pressures.
Serum myoglobin concentration was elevated 40 and min after the incident, whereas there were no changes in CK-MB or TnT. The ultimate cause of syncope in this diver probably was a decrease in cerebral perfusion following glossopharyngeal insufflation.
The asystolic periods recorded in this diver could possibly indicate that susceptible individuals may be put at risk of a serious cardiac incident if the lungs are excessively overinflated by glossopharyngeal insufflation.
This concern is further substantiated by the observed increase in serum myoglobin concentration after the event. Paced respiration with end-expiration technique offers superior BOLD signal repeatability for breath-hold studies. As a simple, non-invasive method of blood oxygenation level-dependent BOLD signal calibration, the breath-hold task offers considerable potential for the quantification of neuronal activity from functional magnetic resonance imaging fMRI measurements.
With an aim to improve the precision of this calibration method, the impact of respiratory rate control on the BOLD signal achieved with the breath-hold task was investigated. In addition to self-paced breathing, three different computer-paced breathing rates were imposed during the periods between end-expiration breath-hold blocks.
The resulting BOLD signal timecourses and statistical activation maps were compared in eleven healthy human subjects. Results indicate that computer-paced respiration produces a larger peak BOLD signal increase with breath-hold than self-paced breathing, in addition to lower variability between trials. This is due to the more significant post-breath-hold signal undershoot present in self-paced runs, a characteristic which confounds the definition of baseline and is difficult to accurately model.
Interestingly, the specific respiratory rate imposed between breath-hold periods generally does not have a statistically significant impact on the BOLD signal change. This result can be explained by previous reports of humans adjusting their inhalation depth to compensate for changes in rate, with the end-goal of maintaining homeostatic ventilation. The advantage of using end-expiration relative to end-inspiration breath-hold is apparent in view of the high repeatability of the BOLD signal in the present study, which does not suffer from the previously reported high variability associated with uncontrolled inspiration depth when using the end-inspiration technique.
The aim of this study was to assess the validity and accuracy of a commercial linear encoder Musclelab, Ergotest, Norway to estimate Bench press 1 repetition maximum 1RM from the force – velocity relationship.
Twenty seven physical education students and teachers 5 women and 22 men with a heterogeneous history of strength training participated in this study. They performed a 1 RM test and a force – velocity test using a Bench press lifting task in a random order.
Mean 1 RM was Additional studies are required to determine whether accuracy is affected by age, sex or initial level. Key pointsSome commercial devices allow to estimate 1 RM from the force- velocity relationship. These estimations are valid. However, their accuracy is not high enough to be of practical help for training intensity prescription.
Day-to-day reliability of force and velocity measured by the linear encoder has been shown to be very high, but the specific reliability of 1 RM estimated from the force- velocity relationship has to be determined before concluding to the usefulness of this approach in the monitoring of training induced adaptations. Key points Some commercial devices allow to estimate 1 RM from the force- velocity relationship. Breath-hold device for laboratory rodents undergoing imaging procedures. The increased use in noninvasive imaging of laboratory rodents has prompted innovative techniques in animal handling.
Lung imaging of rodents can be a difficult task because of tissue motion caused by breathing, which affects image quality. The use of a prototype flat-panel computed tomography unit allows the acquisition of images in as little as 2, 4, or 8 s. This short acquisition time has allowed us to improve the image quality of this instrument by performing a breath-hold during image acquisition. We designed an inexpensive and safe method for performing a constant-pressure breath-hold in intubated rodents.
Initially a prototypic manual 3-way valve system, consisting of a 3-way valve, an air pressure regulator, and a manometer, was used to manually toggle between the ventilator and the constant-pressure breath-hold equipment. The success of the manual 3-way valve system prompted the design of an electronically actuated valve system. In the electronic system, the manual 3-way valve was replaced with a custom designed 3-way valve operated by an electrical solenoid.
The electrical solenoid is triggered by using a hand-held push button or a foot pedal that is several feet away from the gantry of the scanner. This system has provided improved image quality and is safe for the animals, easy to use, and reliable. Premotor neurons encode torsional eye velocity during smooth-pursuit eye movements.
Responses to horizontal and vertical ocular pursuit and head and body rotation in multiple planes were recorded in eye movement-sensitive neurons in the rostral vestibular nuclei VN of two rhesus monkeys. When tested during pursuit through primary eye position, the majority of the cells preferred either horizontal or vertical target motion. During pursuit of targets that moved horizontally at different vertical eccentricities or vertically at different horizontal eccentricities, eye angular velocity has been shown to include a torsional component the amplitude of which is proportional to half the gaze angle “half-angle rule” of Listing’s law.
Multiple linear regression analysis revealed a significant contribution of torsional eye movement sensitivity to the responsiveness of the cells.
These findings suggest that many VN neurons encode three-dimensional angular velocity , rather than the two-dimensional derivative of eye position, during smooth-pursuit eye movements. Although no clear clustering of pursuit preferred-direction vectors along the semicircular canal axes was observed, the sensitivity of VN neurons to torsional eye movements might reflect a preservation of similar premotor coding of visual and vestibular-driven slow eye movements for both lateral-eyed and foveate species.
Purpose: To study the oxygen saturation SO2 and breath-holding time variation applied active breathing control ABC in radiotherapy of tumor. And the patient monitor was used to observe the oxygen saturation SO2 variation. The variation of SO2, and length of breath-holding time and the time for recovering to the initial value of SO2 were recorded and analyzed.
And the breath-holding time shortened obviously for patients whose SO2 did not recover to normal. It is necessary to check the SO2 variation in breath training, and enough time should be given to recover SO2. We describe a clinical case study surrounding the behavioral assessment and operant treatment of, an adult with severe mental retardation who engaged in chronic breath-holding.
In this clinical case, previous neurological and medical testing had ruled out biological bases for the individual’s breath-holding. A functional behavioral assessment…. Agreement and repeatability of vascular reactivity estimates based on a breath-hold task and a resting state scan. By complementing a task-related BOLD acquisition with a vascular reactivity measure obtained through breath-holding or hypercapnia, this unwanted variance can be statistically reduced in the BOLD responses of interest.
Recently, it has been suggested that vascular reactivity can also be estimated using a resting state scan. This study aimed to compare three breath-hold based analysis approaches block design, sine—cosine regressor and CO2 regressor and a resting state approach CO2 regressor to measure vascular reactivity.
We tested BOLD variance explained by the model and repeatability of the measures. Fifteen healthy participants underwent a breath-hold task and a resting state scan with end-tidal CO2 being recorded during both. Maps and regional vascular reactivity estimates showed high repeatability when the breath-hold task was used. Repeatability and variance explained by the CO2 trace regressor were lower for the resting state data based approach, which resulted in highly variable measures of vascular reactivity.
We conclude that breath-hold based vascular reactivity estimations are more repeatable than resting-based estimates, and that there are limitations with replacing breath-hold scans by resting state scans for vascular reactivity assessment.
Both CO 2 inhalation followed by hyperventilation and breath-holding have been utilized to measure cerebral vasomotor reactivity VMR but their correlation has been poorly studied and understood. A retrospective study was conducted in subjects The mean BHI was 0. Move dish and sample into the cell culture This study aimed to compare three breath-hold based analysis approaches block design, sine-cosine regressor and CO2 regressor and a resting state approach CO2 regressor to measure vascular reactivity.
Published by Elsevier Inc. Boson sampling is a problem strongly believed to be intractable for classical computers, but can be naturally solved on a specialized photonic quantum simulator. The protocol requires only one single-photon source, two detectors, and a loop-based interferometer for an arbitrary number of photons. The single-photon pulse train is time-bin encoded and deterministically injected into an electrically programmable multimode network.
The observed three- and four-photon boson sampling rates are Volumetric velocity measurements in restricted geometries using spiral sampling : a phantom study. The aim of this study was to evaluate the accuracy of maximum velocity measurements using volumetric phase-contrast imaging with spiral readouts in a stenotic flow phantom. In a phantom model, maximum velocity , flow, pressure gradient, and streamline visualizations were evaluated using volumetric phase-contrast magnetic resonance imaging MRI with velocity encoding in one extending on current clinical practice and three directions for characterization of the flow field using spiral readouts.
Results of maximum velocity and pressure drop were compared to computational fluid dynamics CFD simulations, as well as corresponding low-echo-time TE Cartesian data. Flow was compared to 2D through-plane phase contrast PC upstream from the restriction. Results obtained with 3D through-plane PC as well as 4D PC at shortest TE using a spiral readout showed excellent agreements with the maximum velocity values obtained with CFD velocity location, as well as the accurate velocity quantification can be obtained in stenotic regions using short-TE spiral volumetric PC imaging.
Marijuana smoking: effects of varying puff volume and breathhold duration. Two studies were conducted to quantify biological and behavioral effects resulting from exposure to controlled doses of marijuana smoke. Each study also varied levels of delta 9-tetrahydro-cannabinol marijuana cigarette content 1. Subjects smoked 10 puffs in each of six sessions; a seventh, nonsmoking session all measures recorded at the same times as in active smoking sessions served as a control.
Variations in puff volume produced significant dose-related changes in postsmoking plasma delta 9-tetrahydro-cannabinol levels, carbon monoxide boost and subjective effects e. In contrast, breathholding for 10 or 20 sec versus 0 sec increased plasma delta 9-tetrahydro-cannabinol levels but not CO boost or subjective effects. Task performance measures were not reliably influenced by marijuana smoke exposure within the dosing ranges examined.
These findings confirm the utility of the controlled smoking technology, support the notion that cumulative puff volume systematically influences biological exposure and subjective effects, but cast doubt on the common belief that prolonged breathholding of marijuana smoke enhances classical subjective effects associated with its reinforcing value in humans. Zhang, Ziheng; Dione, Donald P. A novel MR imaging technique, spatial modulation of magnetization with polarity alternating velocity encoding SPAMM-PAV , is presented to simultaneously examine the left ventricular early diastolic temporal relationships between myocardial deformation and intra-cavity hemodynamics with a high temporal resolution of 14 ms.
This approach is initially evaluated in a dynamic flow and tissue mimicking phantom. A comparison of regional longitudinal strains and intra-cavity pressure differences integration of computed in-plane pressure gradients within a selected region in relation to mitral valve inflow velocities is performed in eight normal volunteers. Our results demonstrate that apical regions have higher strain rates 0.
This pattern is reversed during the deceleration period, when the strain-rates in the basal regions are the highest 0. A positive base-to-apex gradient in peak pressure difference is observed during acceleration, followed by a negative base-to apex gradient during deceleration. These studies shed insight into the regional volumetric and pressure difference changes in the left ventricle during early diastolic filling.
Breast tumor hemodynamic response during a breath-hold as a biomarker to predict chemotherapeutic efficacy: preclinical study. Therefore, it requires a perturbation of physiological signals, such as blood flow and oxygenation. In that sense, a few groups reported that monitoring a relative hemodynamic change during a breast tissue compression or a breath-hold to a patient can provide good contrast between tumor and nontumor. However, no longitudinal study reports the utilization of a breath-hold to predict tumor response during chemotherapy.
A continuous wave near-infrared spectroscopy was employed to monitor hemodynamics in rat breast tumor during a hyperoxic to normoxic inhalational gas intervention to mimic a breath-hold during tumor growth and chemotherapy.
The reduced oxyhemoglobin concentration during inhalational gas intervention correlated well with tumor growth, and it responded one day earlier than the change of tumor volume after chemotherapy. In conclusion, monitoring tumor hemodynamics during a breath-hold may serve as a biomarker to predict chemotherapeutic efficacy of tumor. Left ventricle changes early after breath-holding in deep water in elite apnea divers. To study by ultrasounds cardiac morphology and function early after breath-hold diving in deep water in elite athletes.
Each subject performed a series of three consecutive breath-hold dives and 40 m depth. End-diastolic left ventricular LV diameter EDD and end-diastolic LV volume EDV increased significantly p breath-hold diving due to favorable changes in loading conditions relative to pre-diving, namely the recruitment of left ventricular preload reserve and the reduction in afterload.
Dark chocolate reduces endothelial dysfunction after successive breath-hold dives in cool water. The aim of this study is to observe the effects of dark chocolate on endothelial function after a series of successive apnea dives in non-thermoneutral water.
Twenty breath-hold divers were divided into two groups: a control group 8 males and 2 females and a chocolate group 9 males and 1 female. The chocolate group performed the dives 1 h after ingestion of 30 g of dark chocolate. A significant decrease in FMD was observed in the control group after the dives No differences in digital photoplethysmography and peroxynitrites were observed between before and after the dives.
Antioxidants contained in dark chocolate scavenge free radicals produced during breath-hold diving. Ingestion of 30 g of dark chocolate 1 h before the dive can thus prevent endothelial dysfunction which can be observed after a series of breath-hold dives. Validation of high temporal resolution spiral phase velocity mapping of temporal patterns of left and right coronary artery blood flow against Doppler guidewire.
Temporal patterns of coronary blood flow velocity can provide important information on disease state and are currently assessed invasively using a Doppler guidewire.
A non-invasive alternative would be beneficial as it would allow study of a wider patient population and serial scanning. A retrospectively-gated breath-hold spiral phase velocity mapping sequence TR 19 ms was developed at 3 Tesla. Velocity maps were acquired in 8 proximal right and 15 proximal left coronary arteries of 18 subjects who had previously had a Doppler guidewire study at the time of coronary angiography.
Cardiovascular magnetic resonance CMR velocity -time curves were processed semi-automatically and compared with corresponding invasive Doppler data. High temporal resolution breath-hold spiral phase velocity mapping underestimates absolute values of coronary flow velocity but allows accurate assessment of the temporal patterns of blood flow. MR imaging of the human heart without explicit cardiac synchronization promises to extend the applicability of cardiac MR to a larger patient population and potentially expand its diagnostic capabilities.
However, conventional non-gated imaging techniques typically suffer from low image quality or inadequate spatio-temporal resolution and fidelity. Patient-Adaptive Reconstruction and Acquisition in Dynamic Imaging with Sensitivity Encoding PARADISE is a highly-accelerated non-gated dynamic imaging method that enables artifact-free imaging with high spatio-temporal resolutions by utilizing novel computational techniques to optimize the imaging process.
In addition to using parallel imaging, the method gains acceleration from a physiologically-driven spatio-temporal support model; hence, it is doubly accelerated. The support model is patient-adaptive, i. The proposed method is also doubly adaptive as it adapts both the acquisition and reconstruction schemes. Based on the theory of time-sequential sampling , the proposed framework explicitly accounts for speed limitations of gradient encoding and provides performance guarantees on achievable image quality.
Determination of ethane, pentane and isoprene in exhaled air–effects of breath-holding , flow rate and purified air. Exhaled ethane, pentane and isoprene have been proposed as biomarkers of oxidative stress.
The objectives were to explore whether ethane, pentane and isoprene are produced within the airways and to explore the effect of different sampling parameters on analyte concentrations. The flow dependency of the analyte concentrations, the concentrations in dead-space and alveolar air after breath-holding and the influence of inhaling purified air on analyte concentrations were investigated.
The analytical method involved thermal desorption from sorbent tubes and gas chromatography. The studied group comprised 13 subjects with clinically stable asthma and 14 healthy controls. After breath-holding , no significant changes in ethane levels were observed. Pentane and isoprene levels increased significantly after 20 s of breath-holding. Inhalation of purified air before exhalation resulted in a substantial decrease in ethane levels, a moderate decrease in pentane levels and an increase in isoprene levels.
The major fractions of exhaled ethane, pentane and isoprene seem to be of systemic origin. There was, however, a tendency for ethane to be flow rate dependent in asthmatic subjects, although to a very limited extent, suggesting that small amounts of ethane may be formed in the airways. Double-blind, placebo-controlled trial on the effect of piracetam on breath-holding spells.
Breath-holding spells BHS are apparently frightening events occurring in otherwise healthy children. The aim of this study was to evaluate the efficacy of piracetam in the treatment of breath-holding spells.
Forty patients with BHS who were classified into two groups were involved in a double-blinded placebo-controlled prospective study. Piracetam was given to group A while group B received placebo. Patients were followed monthly for a total period of 4 months. There was a significant decline of number of attacks after piracetam treatment compared to placebo p value breath-holding spells in children. Evaluation of correlation between physical properties and ultrasonic pulse velocity of fired clay samples.
The aim of this study is to establish a correlation between physical properties and ultrasonic pulse velocity of clay samples fired at elevated temperatures. Brick-making clay and pottery clay were studied for this purpose. A commercial ultrasonic testing instrument Proceq Pundit Lab was used to evaluate the ultrasonic pulse velocity measurements for each fired clay sample as a function of temperature.
It was observed that there became a relationship between physical properties and ultrasonic pulse velocities of the samples. The results showed that in consequence of increasing densification of the samples , the differences between the ultrasonic pulse velocities were higher with increasing temperature. These findings may facilitate the use of ultrasonic pulse velocity for the estimation of physical properties of fired clay samples.
In a series of breath-hold acquisitions, three-dimensional data were acquired initially for prospective image registration of subsequent BOLD measurements. Prospective image registration and BOLD imaging of each kidney was achieved within a total measurement time of about 17 s, enabling its execution within a single breath-hold. Magn Reson Med , Sensory neurons integrate information about the world, adapting their sampling to its changes.
However, little is understood mechanistically how this primary encoding process, which ultimately limits perception, depends upon stimulus statistics. Here, we analyze this open question systematically by using intracellular recordings from fly Drosophila melanogaster and Coenosia attenuata photoreceptors and corresponding stochastic simulations from biophysically realistic photoreceptor models.
Simulations reveal how a photoreceptor’s information capture depends critically upon the stochastic refractoriness of its 30, sampling units microvilli. In daylight, refractoriness sacrifices sensitivity to enhance intensity changes in neural image representations, with more and faster microvilli improving encoding. But for GWN and other stimuli, which lack longer dark contrasts of real-world intensity changes that reduce microvilli refractoriness, these performance gains are submaximal and energetically costly.
Decompression sickness in breath-hold divers: a review. Although it has been generally assumed that the risk of decompression sickness is virtually zero during a single breath-hold dive in humans, repeated dives may result in a cumulative increase in the tissue and blood nitrogen tension. Many species of marine mammals perform extensive foraging bouts with deep and long dives interspersed by a short surface interval, and some human divers regularly perform repeated dives to m or a single dive to more than m, all of which may result in nitrogen concentrations that elicit symptoms of decompression sickness.
Neurological problems have been reported in humans after single or repeated dives and recent necropsy reports in stranded marine mammals were suggestive of decompression sickness-like symptoms. Modelling attempts have suggested that marine mammals may live permanently with elevated nitrogen concentrations and may be at risk when altering their dive behaviour. In humans, non-pathogenic bubbles have been recorded and symptoms of decompression sickness have been reported after repeated dives to modest depths.
The mechanisms implicated in these accidents indicate that repeated breath-hold dives with short surface intervals are factors that predispose to decompression sickness. Optimising diffusion-weighted MR imaging for demonstrating pancreatic cancer: a comparison of respiratory-triggered, free-breathing and breath-hold techniques.
Two radiologists, independently and blindly, assigned total image quality scores [sum of rating diffusion images lesion detection, anatomy, presence of artefacts and ADC maps lesion characterisation, overall image quality ] per technique and ranked them.
Total image quality scores for respiratory-triggered, free-breathing and breath-hold techniques were The respiratory-triggered technique had a significantly higher ranking. Lesion SI on all b-values and signal-to-noise ratio on b and b were significantly higher for the respiratory-triggered technique. For respiratory-triggered, free-breathing and breath-hold techniques the mean ADCs were 1. Anonymized images were randomized for blinded review by two independent readers for image quality, artifact severity in 8 defined vessel segments and aortic dimensions in 6 standard sites.
Comparison and reproducibility of ADC measurements in breathhold , respiratory triggered, and free-breathing diffusion-weighted MR imaging of the liver. To compare and determine the reproducibility of apparent diffusion coefficient ADC measurements of the normal liver parenchyma in breathhold , respiratory triggered, and free-breathing diffusion-weighted magnetic resonance imaging DWI.
Eleven healthy volunteers underwent three series of DWI. ADCs of the liver parenchyma were compared by using nonparametric tests. Reproducibility was assessed by the Bland-Altman method.
ADC measurements of the normal liver parenchyma in respiratory triggered DWI are significantly higher and less reproducible than in breathhold and free-breathing DWI. Copyright c Wiley-Liss, Inc. Qualitative assessment of contrast-enhanced magnetic resonance angiography using breath-hold and non-breath-hold techniques in the portal venous system.
The purpose of this study is to evaluate the image quality in delineation of the portal venous systems with two different methods, breath-hold and non-breath-hold by using the 3D FLASH sequence. We used a 1. Our study showed contrast-enhanced 3D FLASH MR angiography, together with the breath-hold technique, may provide reliable and accurate information on the portal venous system.
Time-instant sampling based encoding of time-varying acoustic spectrum. The inner ear has been shown to characterize an acoustic stimuli by transducing fluid motion in the inner ear to mechanical bending of stereocilia on the inner hair cells IHCs. Subsequently, the afferent auditory nerve fiber ANF bundle samples the encoded waveform in the IHCs by synapsing with them. In this work we focus on sampling of information by afferent ANFs from the IHCs, and show computationally that sampling at specific time instants is sufficient for decoding of time-varying acoustic spectrum embedded in the acoustic stimuli.
The approach is based on sampling the signal at its zero-crossings and higher-order derivative zero-crossings. We show results of the approach on time-varying acoustic spectrum estimation from cricket call signal recording. The framework gives a time-domain and non-spatial processing perspective to auditory signal processing.
The approach works on the full band signal, and is devoid of modeling any bandpass filtering mimicking the BM action. Instead, we motivate the approach from the perspective of event-triggered sampling by afferent ANFs on the stimuli encoded in the IHCs. Though the approach gives acoustic spectrum estimation but it is shallow on its complete understanding for plausible bio-mechanical replication with current mammalian auditory mechanics insights.
Reflex anoxic seizures ‘white breath-holding ‘ : nonepileptic vagal attacks. From clinical history 58 children were diagnosed as having reflex anoxic seizures secondary to provoked cardioinhibition also known as white breath-holding attacks. Before referral, these seizures were commonly misdiagnosed as epileptic either because the provocation was ignored, not recognised, or was a febrile illness, or because there was no crying, no obvious breath-holding , little cyanosis, and often no pallor to suggest syncope and cerebral ischaemia.
Download Free PDF. When will taxonomic saturation be achieved? A case study in Nunduva and Kyrtuthrix Rivulariaceae, Cyanobacteria. Nunduva and Kyrtuthrix especially useful to systematists, both for evaluating remain morphologically and phylogenetically separate classical genera and species, as well as for character- even with the addition of new species. However, how izing genera and species new to science.
We are in a long will this remain the case? Many new genera and period of rapid and radical taxonomic discovery species of cyanobacteria have recently been described. Will we start to see multiple populations for new species. This period of discovery of algal taxa is the same cryptic species, or will future taxonomists not unique to the cyanobacteria Guiry but collapse multiple species into fewer species, or certainly the rate of discovery in this phylum rivals multiple genera into single genera.
The description of taxonomic discovery in other algal phyla even even more Nunduva and Kyrtuthrix species causes us to though cyanobacterial taxonomists are relatively few pause and evaluate the future of cyanobacterial in number. These same questions are faced by algal In most instances, when new genera have been taxonomists studying other phyla, and the resolution described, they contain only a single new species may ultimately be similar.
Casamatta et al. Accepted 8 June Alvarenga et al. Multiple species have In this study, we have collected additional strains sometimes been described with the description of a of Rivulariaceae Nostocales from the marine inter- new genus Engene et al. These strains are similar morphologically et al.
We doubled the number of species in a rela- multiple species in a new genus consisting of multi- tively new genus Nunduva and a recently ple new combinations as a result of revision of poly- molecularly characterized classical genus Kyr- phyletic genera e. In a number of instances, limited number of new taxa, and will address the after the initial description of a new genus, more question: Will our current taxonomic criteria with- species have been discovered in the genus once it stand the continual addition of new observations as has molecular definition.
Examples of such discov- the field of cyanobacterial systematics progresses? Source of material and morphological characterization. Samples , Aguiar et al. Each sample was divided into three parts: Cellamare et al.
Morphological characteri- and Myxacorys, now with three species each Alvar- zation was performed on formalin-preserved samples of different populations.
Semipermanent slides were prepared, enga et al. Epifluo- et al. We also know of instances where addi- rescence images were obtained with an Olympus Provis AX70 tional species have been found but not described in microscope. Will there come a saturation point where Material isolation and strains.
Dry samples were rehydrated with sterile seawater on a microscope slide, and filaments the discontinuities separating species disappear as were isolated through serial dilutions in drops of seawater. Will we eventually reach a point then afterward rinsing four or five times with liquid SN med- where authors begin to combine multiple species in ium Waterbury et al.
The seawater was filtered with 0. Bootstrapping with 1, replicates cyanobacterial culture include C and C Sequences was conducted for both analyses. The instead of a K number e. The final average standard deviation of and VRF1 sensu Boyer et al.
The potential scale reduction fac- et al. The PCR amplification was performed with an tor PSRF value for all the estimated parameters in the Baye- Eppendorf Mastercycler following the conditions described by sian analysis was 1. One or two Analyses based on an unrooted alignment of the 16SS clones with verified long PCR products were then chosen for ITS region for all Nunduva and Kyrtuthrix species for which each strain for sequencing at the Biotechnology Institute, sequence exists was also conducted.
The neighbor-joining NJ analysis was conducted software version 7. Bootstrap values from these two analyses were ples with multiple sequences of Nunduva and Kyrtuthrix are mapped on to the nodes in the Bayesian inference BI anal- reported in the phylogenetic analyses in this article. In the BI analysis, indels in the ITS region were coded 0 Additionally and complementary to the morphological and absent and 1 present. The secondary structures 0. The sequences were assembled and cor- our strains, with additional related taxa from the 16S rRNA rected using BioEdit software version 7.
In addition to Nunduva and Kyrtuthrix species, we and Sequencher 4. Nunduva Chroococcidiopsis thermalis AB All sequences were was a well-supported clade 1.
Nunduva, Kyrtuthrix, Rivularia, Phylogenetic relationships were inferred with maximum and Phyllonema are members of Rivulariaceae 1. The expanded phylogeny upon which this collapsed tree is based can be found in supplemen- tal materials Fig. The Box-B helices showed much greater difference b. Calotrichaceae is well-removed from Rivu- in structure among species than the D1—D10 helices lariaceae, being a clade within the mixed Nostocales Fig. There were two exceptional pairs that in our analysis see Fig.
S1 in the Supporting Infor- shared the secondary structure exactly. The 16S analyses structure but differed in three nucleotides in the ter- also supported past and present species of both minal loop Fig. Nunduva sanangustinensis Nunduva and Kyrtuthrix in that all species for which and N. Two sequence Fig. Sequence data from all tuthrix were sufficiently similar that an alignment strains in this study supported an extension of the could be made with both taxa Table S1 in the Sup- basal clamp of the Box-B helices due to complemen- porting Information.
Nunduva and Kyrtuthrix were strains examined Fig. The Nunduva species well-separated, and species were monophyletic where were identical in possession of the same four base multiple strains of the same species were sequenced. The other Rivulariaceae representa- Information provided strong evidence for the tives were different in both the sequence and the recognition of eight species within Nunduva, of structure of the basal clamps, as well as the upper which four were previously described N.
With the exception of N. In environmental material, thallus is species CKM23, the first two being caespitose up to 0.
Filaments are iso- and heteropo- Fig. This pattern was universal in lar, slightly curved, with double and single false Kyrtuthrix species and the most common in Nunduva branching, 20—30 lm wide. Trichomes are not to species. The second structure had a small terminal slightly constricted, 9—15 lm wide. Cells are shorter loop of five nucleotides that was separated from a lar- than wide, 3—6 lm long. Heterocytes are shorter ger subterminal bilateral bulge by two base pairs than wide.
Reproduction is by hormogonia 40— Fig. Nunduva species CK 60 lm long, mainly isopolar, formed by trichome M22 possessed a unique terminal structure Fig. The D1—D10 helix was identical in sequence and generally developing into heteropolar young fila- structure for K. Akinetes are not observed. CKM23 Fig. The representa- In culture, filaments are heteropolar with lamel- tives of Rivularia and Phyllonema differed notably in lated, hyaline sheaths Fig.
Trichomes con- structure and sequence of the D1—D10 helix Fig. TABLE 1. Percent dissimilarity for strains of Nunduva and Kyrtuthrix for which ITS sequence data are available. PCC CKM22 CEc-M59 When 3. For a more extensive Table of percent dissimilarity, see Table S2. Cells are granulated, shorter than wide Fig. Necridia is uncommon, light blue- material prepared from isolate CK Secondary structures for the D1—D10 helices of Nunduva and Kyrtuthrix taxa treated in this study, with Rivularia and Phyllonema serving as related outgroups in the Rivulariaceae for comparison.
Nucleotides in circles represent variation seen either within species or within different operons in the same strain. In no instance did these substitutions result in a change in structure.
Etymology: komarkovae L. Filaments are iso- and heteropolar, Ecology and distribution: Epilithic on intertidal slightly curved, with double and single false fringes C58 K82, CK Trichomes are not slightly constricted, 8— Observations: In environmental material, frequently 16 lm wide.
When mature, isopolar filaments this species presents a small apical bead-like protu- sometimes erect at both attenuated ends and fre- berance only reported for N. This species quently forming hair Fig. Cells are shorter does not form apical hair.
In culture, it develops than wide, 4—9 lm long. Apical cells are slightly abundant one-celled to few-celled hormogonia in attenuated, sometimes forming a short, non- chains.
See Table S3 in the Supporting Informa- hyaline hair. Heterocytes are scarce, generally tion for further details. In environmental material, thallus is mainly by biconcave lens-shaped necridia or tri- caespitose up to 1—2 mm high, formed by blue- chome fragmentation, generally developing into green to dark green apically attenuated filaments, heteropolar young filaments Fig.
Akinetes densely entangled at the base with basal and are not observed. Secondary structures for the Box-B helices of Nunduva and Kyrtuthrix taxa treated in this study, with Rivularia and Phyllonema serving as related outgroups in the Rivulariaceae for comparison. Nucleotides in circles represent variation seen within Nunduva komarko- vae. This substitution results in a mismatch that opens the terminal loop by two nucleotides. In culture, filaments are heteropolar with lamel- a widened sheath Fig.
Basal hormogonia lated, hyaline, apically open sheaths Fig. Trichomes constricted at cross-walls, thickened every cell has the ability to develop into small iso- or at the base, gradually attenuated, and ending in a heteropolar hormogonia that are released Fig. Cells are granulated, shorter E, H—J. Heterocytes are October L. Sequences were obtained cal to oval-cylindrical, complanate, solitary, and for cultured isolate CK Secondary structures for the V3 helices of Nunduva and Kyrtuthrix taxa treated in this study, with Rivularia and Phyllonema serv- ing as related outgroups in Rivulariaceae for comparison.
Nucleotides in circles represent variation seen within ribosomal operons in Nun- duva biania. These substitutions did not result in a change in structure. Table S3 for further details. Ecology and distribution: Epilithic on supratidal fringes Kyrtuthrix munecosensis J.
TABLE 2. Comparison of nucleotide lengths of conserved domains in the 16SS ITS region for Nunduva and Kyrtuthrix strains treated in this study. Filaments are platform C, up to 0—1 m ASL ; epilithic in par- apically attenuated, isopolar, folded at the base, com- tially sunny and exposed granitic rock.
Single, individual filaments 9—17 20 lm tuthrix huatulcensis and K. Trichomes are slightly to very con- sheath as compared with hormogonia from those stricted at cross-walls, 4. Cells are variably species See Table S4 in the Supporting Informa- shaped, from subquadrate to trapezoidal or barrel- tion for further details. In environmental material, thalli are long 4. Repro- crustaceous flat, up to 1 cm in diameter, formed by duction is by terminal iso- or heteropolar, generally colonies of blue-green to dark green parallelly dis- thin hormogonia, 4—7 lm wide Sequences were the upper apices.
Filaments are isopolar folded at the obtained from environmental sample CE. April base, forming generally simple loops and occasionally 23, Morphological traits of Nunduva komarkovae.
A—K Culture material. A Thallus showing parallel and entangled arrangement of filaments. B—D Heteropolar filaments. J—I Lamellate hyaline sheaths. F—J Hormogonia formation, iso- and heteropolar. B, K Fila- ments showing apical cells without hair. L—O Nunduva komarkovae environmental samples. K Basal heterocyte. L Caespitose thallus with yellowish to ochre sheath.
M Apical cell slightly attenuated with no hair. N Trichome fragmentation. O Intercalary heterocyte. Single, indi- commonly very constricted but with long series of simi- vidual filaments 8—10 lm wide and double folded lar width cells 5—8 lm wide Fig. Cells are 13—24 lm wide. Morphological traits of Nunduva sanagustinensis. A—D Environmental sample. A—B Thallus caespitose showing attenuated fila- ments and non-hyaline hair.
B—C Basal part with densely entangled filaments. D Heteropolar hormogonia. E—K Nunduva sanagusti- nensis morphological traits of culture material. E Simple false branched filaments. F, K Granulated cytoplasm constricted cells. G—J Development of basal hormogonia into thick-sheathed flexuous or fragmented hormogonia. Heterocytes are solitary, Fragmentation is by terminal iso- or heteropolar, gen- intercalar or terminal in some hormogonia, variable erally thin, hormogonia, 3—5 lm wide, 25—51 lm long from subspherical, short cylinders to quadrate 4 5—6 Fig.
Morphological traits of Kyrtuthrix munecosensis. A—K Environmental samples. A—C Thallus showing filaments with parallel arrangement with diffluent sheath. D—F, J Stages of loop development. I, K Heteropolar and isopolar arrow hormogonia develop- ment. H Intercalary heterocyte asterisk. Etymology: totonaca L. Cells are blue-green, variably shaped, platform C, up to 0—1 m ASL ; epilithic in par- 4—7. Heterocytes are intercalary, uncom- tially sunny and exposed granitic rock.
Hormogonia Observations: Thalli in environmental material without sheath, with 2—3 semicircular cells, 10— have firm, common sheaths as compared with Kyr- 12 lm long. Trichomes are wider 5—8 lm Type locality: Mexico. Sequences Key to currently described Kyrtuthrix and Nunduva were obtained for environmental sample CEc.
Thallus in nature is a firm mat of isopolar, tapered, erect filaments closely folded at the substrate U-shaped with individual and common sheaths, arranged in a strictly parallel fashion, with no false branches.
Thallus is endolithic in limestone. Thallus is epilithic. Sheaths are hyaline, not lamellated. Sheaths are hyaline to yellow-brown, lamellated. Trichomes are loosely arranged in crust, straight or flexuous, with soft diffluent sheath.
Trichomes are arranged in parallel and tightly appressed with firm sheaths. Cells are 1. Cells are 5—8 lm wide, with hairs 2.
Trichomes are in culture untapered or widened at the apices. Trichomes are never widened at the apices, tapering to a hair in culture. Sheaths are widened at the apices, resembling a flame. Sheaths are open or closed, but not resembling a flame at the apices. Apical cells are abruptly tapering, often with a small bead-like protuberance.
Apical cells are not bead-like, often forming a hair. Thallus is a caespitose mat 2—3 cm high, formed by entangled filaments in fascicles.
Thallus is a caespitose mat maximally 0. Sheath is colorless, and trichomes are constricted at cross walls. Sheath is hyaline to yellow, and trichomes are unconstricted at cross walls. Nunduva is solely epilithic, presence and kind of false branching, and the mor- whereas Kyrtuthrix has both endolithic and epi- phology of basal regions of the trichomes.
The key lithic species. However, both form visible mats on we provide will likely help future researchers recog- rocks in the intertidal and supratidal zones of nize these interesting species, but confusion with coastal marine waters, and both form tapering tri- other tapering marine taxa, such as Calothrix, Brachy- chomes in culture.
Nunduva has three species that trichia, and Scytonematopsis, will likely occur if the do not taper or only slightly taper at the apices material is scarce or if those who identify the species N. The primary morphological difference is available will be very difficult due to the conver- between the two genera is the formation of com- gence of morphology in culture and the absence of pact thalli in Kyrtuthrix with parallelly arranged U- knowledge about thallus characteristics in nature.
An additional separating characteristic is high among all taxa. Secondary structures of con- is that Nunduva possesses single and geminate served domains of the ITS regions are also distinct false branching, whereas Kyrtuthrix does not. This and provide a good means to distinguish species. Most Umezaki , Our species are primarily from coastal Morphological traits of Kyrtuthrix totonaca.
A—J Environmental samples. A—B Thallus showing parallel arrangement of fila- ments in epifluorescence and BF microscopy. C Filament with lateral folding.
D—E Heteropolar hormogonia. F Intercalary hetero- cyte. F—H Lamellated sheath. H—J Filaments showing the formation of loops, and different shaped cells. Brito et al. Some ture Collection have updated the strain on their species-level diversity remains to be resolved taxo- Web site to Nunduva sp. Unfortunately, rect designation proposed by Walter et al. The We made new threshold trasiak et al. It is very clear that 16S used it to recognize cryptic speciation in uncultur- rRNA genetic identities are often uninformative at able populations of Synechococcus spongiarum.
When multiple strains of the same spe- make taxonomic hypotheses? Some researchers have cies are compared, the average PD among strains is postulated that taxonomists will have a more sure typically around 1. When PD is between 3. Certainly, additional been used to recognize different species Mai et al.
Phylogenies based on large numbers of pro- Table 1, Table S2. CEc-M59, and the difference in those two et al. We raised the question in our among genera in the Nostocales will become much Introduction: Will there come a saturation point clearer as more genomes become available, particu- where the discontinuities separating species disap- larly of many of the genera described in the last pear as many more strains are sequenced?
At pre- 20 years. However, we question the use of similarity sent, based on the present study and others, the thresholds based on protein coding genes. An alterna- genetic identities based on 16S rRNA genes among tive proposal was to use a combination of alignment these species.
As an example heterotrophic bacteria Yarza et al. What was of application of thresholds to cyanobacterial taxon- even more remarkable was the high genetic identi- omy, recommendations have been made to collapse ties among the genera of Rivulariaceae. Average all Microcystis species into one species, M.
Only Phyllonema was prokaryotic species with a criterion that is genomic below this threshold Table S5 in the Supporting but much easier to determine and that does not Information. The high genetic similarities among require continual retesting when new species are genera in the Nostocales have been noted previously found, we fundamentally disagree with the concept Flechtner et al. It is still possible to recognize the higher level taxa that have been recently recognized species in these genera based upon their thallus based on the polyphasic approach also satisfy the and filament morphology.
To reduce them all down microbiological criteria for taxonomic recognition to just a few taxa in one or two genera would make at the species, genus, family, and order levels. The them more taxonomically confusing, not less, and morphologically and ecologically complex Nosto- would cause us to lose the ecological information cales show little genetic divergence, and conse- these species will likely communicate when records quently, if genetic thresholds were followed strictly, of their distribution become more available.
We wel- it would require collapsing many heterocytous taxa. If these microbiological, approach that includes morphology, ecology, physi- genome-based thresholds are followed, we answer ology, and single-gene phylogeny.
We welcome the our third question raised in the Introduction, we increased ease with which cyanobacterial cultures will eventually reach a point where authors begin to that are microbial consortia i. We reject discarding the polyphasic or total evi- We consider the best species concept for cyanobac- dence approach in favor of a single threshold teria to be a phylogenetic species concept Mishler approach that discards years of taxonomic pro- and Theriot , Johansen and Casamatta , gress in the study of this morphologically and eco- which is less pragmatic than the prokaryotic species logically interesting phylum.
Phylogenetic species concepts from now? This is impossible to answer at this point. It is developed for eukaryotic species and have been necessary for the evaluation of biodiversity. It is nec- adopted in most recent taxonomic treatments of essary for understanding environmental impacts on cyanobacteria. They are also more in line with histori- our ecosystems.
It is an endeavor that helps us cal taxonomic treatments of cyanobacteria, which gave understand evolutionary processes in diverse lin- weight to the use of morphology in defining genus eages.
Despite our uncertainty concerning of long- and species boundaries. We consider phylogenetic spe- term viability of current taxonomic standards, the cies concepts to also be ideal for many algal groups, criteria for recognition of taxa in cyanobacteria have which are frequently asexual or rarely sexual in their been expanded and tested in the last 20 years, and reproductive strategies.
The biological species concept we feel confident they will continue to serve us, at does not fit these taxa well. Furthermore, the existence least in the near future. The authors wish to thank Karnkowska-Ishikawa et al.
Even preparation of this manuscript Guiry and Guiry The taxa of the reproductively complex seaweeds have authors would like to thank anonymous referees for their been found to harbor cryptic species Lindstrom comments leading to improvement the manuscript. Johansen: Formal analysis lead ; supervi- concepts are theoretically sound in addition to being sion supporting ; writing-original draft lead ; pragmatic in practice. Segal-Kischinevzky: Investigation equal. Desertifilum salka- lead ; writing-original draft supporting ; writing- linema sp.
Phytotaxa — Cai, F. Fottea Com- Aguiar, R. Nostocales, A. A novel epiphytic Cyanobacteria from a wet rocky wall in China. Phycologia cyanobacterial species from the genus Brasilonema causing — Phylogenetically Ahn, A. Genomic diversity unostoc gen. Fottea within the haloalkaliphilic genus Thioalkalivibrio.
Violetonostoc minutum gen et sp. Alvarenga, D. A metage- nov. Nostocales, Cyanobacteria from a rocky substrate in nomics approach to cyanobacterial genomics. Algae Int. Algal Res. Pro- Alvarenga, D. Nostocales, Cyanobacteria , a Phyllonema aviceniicola gen. Fottea — Desmonostoc danxiaense Microbiol. Nostocales, Cyanobacteria from Danxia mountain de Alvarenga, L. Phytotaxa — Esteves-Ferreira, A. Lizieri, C. Rexia erecta Nesi, A.
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