Preliminary Evaluation of a Weibull Function for Fitting Slow-Component Eye Velocity over the Time Course of Caloric-Induced Nystagmus

1989 ◽  
Vol 32 (3) ◽  
pp. 681-687 ◽  
Author(s):  
C. Formby ◽  
B. Albritton ◽  
I. M. Rivera
Keyword(s):  
Time Course ◽  
Slow Component ◽  
Weibull Function ◽  
Preliminary Evaluation ◽  
Mathematical Function ◽  
Before And After ◽  
Best Fitting ◽  
Eye Velocity ◽  
Fitting Parameters ◽  
Weibull Equation

We describe preliminary attempts to fit a mathematical function to the slow-component eye velocity (SCV) over the time course of caloric-induced nystagmus. Initially, we consider a Weibull equation with three parameters. These parameters are estimated by a least-squares procedure to fit digitized SCV data. We present examples of SCV data and fitted curves to show how adjustments in the parameters of the model affect the fitted curve. The best fitting parameters are presented for curves fit to 120 warm caloric responses. The fitting parameters and the efficacy of the fitted curves are compared before and after the SCV data were smoothed to reduce response variability. We also consider a more flexible four-parameter Weibull equation that, for 98% of the smoothed caloric responses, yields fits that describe the data more precisely than a line through the mean. Finally, we consider advantages and problems in fitting the Weibull function to caloric data.

The effects of priming exercise on the V̇O2 slow component and the time-course of muscle fatigue during very-heavy-intensity exercise in humans

2018 ◽  
Vol 43 (9) ◽  
pp. 909-919 ◽  
Author(s):  
Paulo Cesar do Nascimento Salvador ◽  
Kristopher Mendes de Souza ◽  
Ricardo Dantas De Lucas ◽  
Luiz Guilherme Antonacci Guglielmo ◽  
Benedito Sérgio Denadai
Keyword(s):  
Muscle Fatigue ◽  
Time Course ◽  
Slow Component ◽  
Peak Torque ◽  
Fixed Amount ◽  
Prior Exercise ◽  
Before And After ◽  
Priming Exercise ◽  
Male Subjects ◽  
Exercise In Humans

We hypothesized that prior exercise would attenuate the muscle fatigue accompanied by oxygen uptake slow-component (V̇O2SC) behavior during a subsequent very-heavy (VH)-intensity cycling exercise. Thirteen healthy male subjects performed tests to determine the critical power (CP) and the fixed amount of work above CP ([Formula: see text]) and performed 6 square-wave bouts until 3 or 8 min, each at a work rate set to deplete 70% [Formula: see text] in 8 min, with a maximal isokinetic effort before and after the conditions without (VHCON) and with prior exercise (VHEXP), to measure the cycling peak torque decrement. The V̇O2SC magnitude at 3 min (VHCON = 0.280 ± 0.234, VHEXP = 0.116 ± 0.109 L·min−1; p = 0.04) and the V̇O2SC trajectory were significantly lower for VHEXP (VHCON = 0.108 ± 0.042, VHEXP = 0.063 ± 0.031 L·min−2; p < 0.01), leading to a V̇O2SC magnitude at the eighth minute that was significantly lower than VHCON (VHCON = 0.626 ± 0.296 L·min−1, VHEXP = 0.337 ± 0.179; p < 0.01). Conversely, peak torque progressively decreased from pre-exercise to 3 min (Δtorque = 21.5 ± 7.7 vs. 19.6 ± 9.2 Nm) and to 8 min (Δtorque = 29.4 ± 15.8 vs. 27.5 ± 12.0 Nm) at VHCON and VHEXP, respectively, without significant differences between conditions. Regardless of the condition, there was a significant relationship between Δtorque and the V̇O2SC (R2: VHCON = 0.23, VHEXP = 0.25; p = 0.01). Considering that “priming” effects on the V̇O2SC were not accompanied by the muscle force behavior, these findings do not support the hypothesis of a “causal” relationship between the time-course of muscle fatigue and V̇O2SC.

Properties of superior vestibular nucleus flocculus target neurons in the squirrel monkey. II. Signal components revealed by reversible flocculus inactivation

1995 ◽  
Vol 73 (6) ◽  
pp. 2279-2292 ◽  
Author(s):  
Y. Zhang ◽  
A. M. Partsalis ◽  
S. M. Highstein
Keyword(s):  
Firing Rate ◽  
Squirrel Monkey ◽  
Slow Component ◽  
Vestibular Nucleus ◽  
Spontaneous Nystagmus ◽  
Velocity Signal ◽  
Before And After ◽  
The Mean ◽  
Superior Vestibular Nucleus ◽  
Eye Velocity

1. Seven upward eye velocity flocculus target neurons (FTNs) and two flocculus projecting neurons (FPNs) were studied before and after ipsilateral flocculus inactivation by injection of muscimol in the alert squirrel monkey. An additional seven FTNs and seven FPNs recorded from the corresponding FTN and FPN areas were recorded after injection. Response properties of FTNs and FPNs were characterized by visual-vestibular interaction paradigms and were compared before and after flocculus inactivation. 2. In FTNs the mean firing rate increased within 2-5 min after muscimol injection in the flocculus and reached a plateau level in approximately 10-20 min. The average mean firing rate for seven FTNs increased from 117 to 174 spikes/s, a net increase of 57 spikes/s (49%). Accompanying the large increase of the mean firing rate, a spontaneous nystagmus in the darkness developed with the slow phase directed upward and contralateral. 3. The firing rate modulation during visual following of a sinusoidal optokinetic drum (0.5 Hz) decreased within 2-5 min after muscimol injection in the flocculus and reached a level of 0 in approximately 10-20 min for all FTNs. After that, some cells remained unmodulated for the period of recording; other cells gradually reversed their phase and developed a modulation out of phase with drum velocity. The depletion of the visual following eye velocity signal on superior vestibular nucleus (SVN) FTNs accompanied a small but consistent decrease of visual following eye velocity amplitude. The average maximum decrease of eye velocity was 26 +/- 9% (mean +/- SD). 4. After flocculus inactivation, even though the modulation response at 0.5 Hz during visual following was abolished, a slow-component eye velocity signal with the same on direction was revealed by a constant-velocity optokinetic stimulus. It is concluded that there are at least two kinds of eye velocity signals during the optokinetic response. These signals are combined at the FTNs and are subsequently relayed to the oculomotor neurons. The source of the fast component is the flocculus, and the source of the slow component is another, as yet unidentified brain structure. 5. The effect of flocculus inactivation on the modulation amplitude during the vestibuloocular reflex (VOR) in darkness was variable: two cells did not change, two cells decreased, and three cells increased their amplitude. The response phase tended to move toward a phase lead, but the change was small. The effect on VOR suppression was more prominent.(ABSTRACT TRUNCATED AT 400 WORDS)

Sources of activator calcium in rabbit basilar artery

1981 ◽  
Vol 241 (2) ◽  
pp. H129-H133 ◽  
Author(s):  
T. A. McCalden ◽  
J. A. Bevan
Keyword(s):  
Basilar Artery ◽  
Time Course ◽  
Slow Component ◽  
Krebs Solution ◽  
Phasic Contraction ◽  
Intracellular Pool ◽  
Ear Artery ◽  
High K ◽  
Before And After ◽  
K Response

The responses of segments of rabbit basilar and ear arteries to high K+ (K+, 45 mM), norepinephrine (NE, 10(-5) and 10(-7) M), and 5-hydroxytryptamine (5-HT, 10(-7) M) were tested before and after their incubation in calcium (Ca2+)-free Krebs solution for times varying from 2.5 to 60 min. The time course of evolution of the responses to K+ with Ca2+-free conditions in both vessels could be represented by a monoexponential curve. The rates of decline of the responses of amines in the ear artery were similar to K+ at first but then fell off at a slower rate. The decline in K+ contraction and the fast initial decline of the NE contraction may relate to the speed of removal of extracellular calcium, whereas the final slower NE decline reflects depletion of an intracellular pool. In the basilar artery, the NE and K+ response declined in a similar manner, whereas the 5-HT contraction showed a fast and a slow component of decline. These results for the maintained agonist response were confirmed using the Ca2+ influx antagonist, 3-methoxyverapamil (D 600). In addition, a D 600-insensitive phasic contraction was observed in both arteries. These results suggest that the steady-state NE contraction in the basilar artery is almost entirely dependent on loosely bound extracellular Ca2+. This is in contrast to the ear artery, where an additional tightly bound or intracellular Ca2+ pool is used. This source is present in the basilar artery but contributes only to a D 600-insensitive phasic component.

scholarly journals Measuring phenotypic flexibility by transcriptome time‐course analyses during challenge tests before and after energy restriction

2019 ◽  
Vol 33 (9) ◽  
pp. 10280-10290 ◽  
Author(s):  
Inge P. G. Bussel ◽  
Parastoo Fazelzadeh ◽  
Gary S. Frost ◽  
Milena Rundle ◽  
Lydia A. Afman
Keyword(s):  
Time Course ◽  
Energy Restriction ◽  
Phenotypic Flexibility ◽  
Before And After ◽  
Challenge Tests

Preoperative and postoperative cognitive functioning in patients with frontal meningiomas

2003 ◽  
Vol 98 (1) ◽  
pp. 21-31 ◽  
Author(s):  
Oliver Tucha ◽  
Christian Smely ◽  
Michael Preier ◽  
Georg Becker ◽  
Geraldine M. Paul ◽  
...  
Keyword(s):  
Executive Functions ◽  
Cognitive Functioning ◽  
Time Course ◽  
Lesion Size ◽  
Test Battery ◽  
Surgical Removal ◽  
Specific Information ◽  
Content Type ◽  
Before And After ◽  
Fine Print

Object. There is presently no specific information available concerning the nature and course of cognitive deficits caused by intracranial meningiomas. In this prospective study the authors examined the cognitive functioning of patients with frontal meningiomas. Methods. Fifty-four patients with frontal meningiomas were examined neuropsychologically before and after neurosurgery. The test battery consisted of standardized instruments including those assessing memory, attention, visuoconstructive abilities, and executive functions. The time period between pre-and postoperative assessment ranged from 4 to 9 months. The patients' performance was compared with the results in 54 healthy adults who were also assessed twice by using the same test battery in a period ranging from 4 to 9 months. In addition, the effect on cognition of meningioma lateralization, localization, lesion size, edema, brain compression, time course, and the occurrence of preoperative seizures was analyzed. Conclusions. Except in the case of working memory, comparisons of pre- and postoperative assessments of cognition revealed no differences in memory, visuoconstructive abilities, or executive functions, although a postoperative improvement in attentional functions was observed. The results of this study indicate that the surgical removal of frontal meningiomas does not impair patients' cognitive functioning. Furthermore, improvements in attentional functions may occur in these patients.

scholarly journals Preliminary Evaluation of a Cycling Cleat Designed for Diabetic Foot Ulcers

2017 ◽  
Vol 107 (6) ◽  
pp. 475-482 ◽  
Author(s):  
Ryan T. Crews ◽  
Steven R. Smith ◽  
Ramin Ghazizadeh ◽  
Sai V. Yalla ◽  
Stephanie C. Wu
Keyword(s):  
Blood Flow ◽  
Diabetic Foot ◽  
Plantar Pressure ◽  
Tissue Perfusion ◽  
Foot Ulcers ◽  
Preliminary Evaluation ◽  
Diabetic Foot Ulcers ◽  
Time Integral ◽  
Traditional Health ◽  
Before And After

Background: Offloading devices for diabetic foot ulcers (DFU) generally restrict exercise. In addition to traditional health benefits, exercise could benefit DFU by increasing blood flow and acting as thermotherapy. This study functionally evaluated a cycling cleat designed for forefoot DFU. Methods: Fifteen individuals at risk of developing a DFU used a recumbent stationary bicycle to complete one 5-minute cycling bout with the DFU cleat on their study foot and one 5-minute bout without it. Foot stress was evaluated by plantar pressure insoles during cycling. Laser Doppler perfusion monitored blood flow to the hallux. Infrared photographs measured foot temperature before and after each cycling bout. Results: The specialized cleat significantly reduced forefoot plantar pressure (9.9 kPa versus 62.6 kPa, P &lt; .05) and pressure time integral (15.4 versus 76.4 kPa*sec, P &lt; .05). Irrespective of footwear condition, perfusion to the hallux increased (3.97 ± 1.2 versus 6.9 ± 1.4 tissue perfusion units, P &lt; .05) after exercise. Infrared images revealed no changes in foot temperature. Conclusions: The specialized cleat allowed participants to exercise with minimal forefoot stress. The observed increase in perfusion suggests that healing might improve if patients with active DFU were to use the cleat. Potential thermotherapy for DFU was not supported by this study. Evaluation of the device among individuals with active DFU is now warranted.

scholarly journals Preliminary In Vitro Wear Assessment of Ceramic Cemented Femoral Components Coupled with Polyethylene Menisci

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2112
Author(s):  
Saverio Affatato ◽  
Paolo Erani ◽  
Maurizio Fersini ◽  
Vincenzo Contaldi ◽  
Anna Rita Terrizzi ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Wear Resistance ◽  
Monoclinic Phase ◽  
Calf Serum ◽  
Wear Test ◽  
Clinical Test ◽  
Preliminary Evaluation ◽  
Before And After ◽  
Roughness Measurements

Success of total knee replacement (TKR) depends on the prosthetic design and materials. The use of metal components is well established with the disadvantage of allergic reactions. Ceramics have been recently proposed because of high wear resistance, excellent biocompatibility, wettability, and suitable mechanical properties. This study was aimed at investigating in vitro wear resistance of Zirconia Toughened Alumina (ZTA)/Ultra-high-molecular-weight polyethylene (UHMWPE) of TKR femoral components. An in vitro protocol was designed with the application of relevant load profile, 6-degrees-of-freedom knee simulator, and 8 × 105 cycles on the ZTA/UHMWPE configuration under bovine calf serum. Before and after wear test, the femoral components were investigated by using the Scanning Electron Microscope (SEM) and the X-Ray Diffraction (XRD) analyses, and stylus surface roughness measurements. The proposed pre-clinical test yielded repeatable results. In particular, gravimetric results showed that, after 8 × 105 cycles, the mean weight loss of the polyethylene mobile components is 5.3 ± 1.1 mg. The surface roughness measurements (Ramax) performed after the wear test showed no significant variation on the UHMWPE menisci. A slight increase of roughness has been found on the ZTA (0.02 µm before wear test, 0.28 µm after the test). SEM observations did not show significant modification of the surface morphology. Tetragonal to monoclinic phase ratio was measured by XRD before and after wear test to evaluate stability of tetragonal ZrO2 phase. Minimal conversion of tetragonal to monoclinic phase was found from 5.4 to 8%. Although this study is a preliminary evaluation limited to in vitro tests, it provides novel pre-clinical indications about the potential of ceramic TKR femoral components.

scholarly journals Surgeons' Experience of Learning Psychological Skills: A Preliminary Evaluation of a Psychological Skills Training Course

2009 ◽  
Vol 91 (4) ◽  
pp. 321-325 ◽  
Author(s):  
Victoria Mason ◽  
Selina Balloo ◽  
Dominic Upton ◽  
Kamal Heer ◽  
Phil Higton ◽  
...  
Keyword(s):  
Human Factors ◽  
Focus Groups ◽  
Skills Training ◽  
Preliminary Evaluation ◽  
Psychological Skills ◽  
Surgical Performance ◽  
Psychological Skills Training ◽  
Before And After ◽  
Theory Practice Gap ◽  
The Impact

INTRODUCTION A range of human factors have been shown to impact on surgical performance although little is known about the impact of training on the views of surgeons towards these factors or how receptive surgeons are to such training. SUBJECTS AND METHODS This was an observational pilot study using a short questionnaire designed to elicit views of surgeons towards a range of human factors prior to, and immediately following, a course designed to address human factors in surgical performance. Focus groups were also conducted before and immediately after the course to elicit views. RESULTS Of all the human factors assessed, decision-making was rated on a visual analogue scale as having the biggest impact on performance both before and after the course. In general, views of human factors changed following the course, most notably an increase in the extent to which work stress, interpersonal difficulties and personality were believed to affect performance. Three themes emerged from the focus groups: (i) personal professional development; (ii) the relationship between trainer and trainee; and (iii) the changing perspective. CONCLUSIONS Surgeons from a range of specialties are receptive to training on the impact of human factors on performance and this study has shown that views may change following a course designed to address this. Further training to address the theory–practice gap is warranted in addition to an evaluation of its effectiveness.

GABAA-Mediated IPSCs in Piriform Cortex Have Fast and Slow Components With Different Properties and Locations on Pyramidal Cells

1997 ◽  
Vol 78 (5) ◽  
pp. 2531-2545 ◽  
Author(s):  
A. Kapur ◽  
R. A. Pearce ◽  
W. W. Lytton ◽  
L. B. Haberly
Keyword(s):  
Time Course ◽  
Feedback Inhibition ◽  
Slow Component ◽  
Piriform Cortex ◽  
Pyramidal Cells ◽  
Long Term Potentiation ◽  
Companion Paper ◽  
Protective Role ◽  
Functional Roles ◽  
Term Potentiation

Kapur, A., R. A. Pearce, W. W. Lytton, and L. B. Haberly.GABAA-mediated IPSCs in piriform cortex have fast and slow components with different properties and locations on pyramidal cells. J. Neurophysiol. 78: 2531–2545, 1997. A recent study in piriform (olfactory) cortex provided evidence that, as in hippocampus and neocortex, γ-aminobutyric acid-A (GABAA)-mediated inhibition is generated in dendrites of pyramidal cells, not just in the somatic region as previously believed. This study examines selected properties of GABAA inhibitory postsynaptic currents (IPSCs) in dendritic and somatic regions that could provide insight into their functional roles. Pharmacologically isolated GABAA-mediated IPSCs were studied by whole cell patch recording in slices. To compare properties of IPSCs in distal dendritic and somatic regions, local stimulation was carried out with tungsten microelectrodes, and spatially restricted blockade of GABAA-mediated inhibition was achieved by pressure-ejection of bicuculline from micropipettes. The results revealed that largely independent circuits generate GABAA inhibition in distal apical dendritic and somatic regions. With such independence, a selective decrease in dendritic-region inhibition could enhance integrative or plastic processes in dendrites while allowing feedback inhibition in the somatic region to restrain system excitability. This could allow modulatory fiber systems from the basal forebrain or brain stem, for example, to change the functional state of the cortex by altering the excitability of interneurons that mediate dendritic inhibition without increasing the propensity for regenerative bursting in this highly epileptogenic system. As in hippocampus, GABAA-mediated IPSCs were found to have fast and slow components with time constants of decay on the order of 10 and 40 ms, respectively, at 29°C. Modeling analysis supported physiological evidence that the slow time constant represents a true IPSC component rather than an artifactual slowing of the fast component from voltage clamp of a dendritic current. The results indicated that, whereas both dendritic and somatic-region IPSCs have both fast and slow GABAA components, there is a greater proportion of the slow component in dendrites. In a companion paper, the hypothesis is explored that the resulting slower time course of the dendritic IPSC increases its capacity to regulate the N-methyl-d-aspartate component of EPSPs. Finally, evidence is presented that the slow GABAA-mediated IPSC component is regulated by presynaptic GABAB inhibition whereas the fast is not. Based on the requirement for presynaptic GABAB-mediated block of inhibition for expression of long-term potentiation, this finding is consistent with participation of the slow GABAA component in regulation of synaptic plasticity. The lack of susceptibility of the fast GABAA component to the long-lasting, activity-induced suppression mediated by presynaptic GABAB receptors is consistent with a protective role for this process in preventing seizure activity.

Metabolic responses to head-down suspension in hypophysectomized rats

1993 ◽  
Vol 75 (6) ◽  
pp. 2718-2726 ◽  
Author(s):  
C. R. Woodman ◽  
C. M. Tipton ◽  
J. Evans ◽  
J. K. Linderman ◽  
K. Gosselink ◽  
...  
Keyword(s):  
Muscle Mass ◽  
Time Course ◽  
Citrate Synthase ◽  
O2 Consumption ◽  
Hindlimb Muscles ◽  
Impaired Ability ◽  
Norepinephrine Concentration ◽  
Hindlimb Muscle ◽  
Before And After ◽  
Hypophysectomized Rats

Rats exposed to head-down suspension (HDS) exhibit reductions in maximal O2 consumption (VO2max) and atrophy of select hindlimb muscles. This study tested the hypothesis that an endocrine-deficient rat exposed to HDS would not exhibit reductions in VO2max or hindlimb muscle mass. Hypophysectomized (HYPX) and sham-operated (SHAM) rats were tested for VO2max before and after 28 days of HDS or cage control (CC) conditions. No significant reductions in VO2max were observed in HYPX rats. In contrast, SHAM-HDS rats exhibited a significant reduction in absolute (-16%) and relative (-29%) measures of aerobic capacity. Time course experiments revealed a reduction in VO2max in SHAM-HDS rats within 7 days, suggesting that cardiovascular adjustments to HDS occurred in the 1st wk. HDS was associated with atrophy of the soleus (-42%) in SHAM rats, whereas HYPX rats exhibited atrophy of the soleus (-36%) and plantaris (-13%). SHAM-HDS rats had significantly lower (-38%) soleus citrate synthase activities per gram muscle mass than SHAM-CC, but no significant differences existed between HYPX-HDS and -CC rats. HDS rats had an impaired ability to thermoregulate, as indicated by significantly greater temperature increases per unit run time, compared with their CC counterparts. Pretreatment plasma epinephrine levels were significantly lower in HYPX than in SHAM rats. Norepinephrine concentration was similar for all groups except HYPX-HDS, in which it was significantly higher. HDS had no significant effect on thyroxine or triiodothyronine. SHAM-HDS rats had significantly lower concentrations of testosterone and growth hormone.(ABSTRACT TRUNCATED AT 250 WORDS)

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