The use of a neck brace does not influence visual vertical perception

Subjective visual vertical (SVV) evaluates the individual's capacity to determine the vertical orientation. Using a neck brace (NB) allow volunteers' heads fixation to reduce cephalic tilt during the exam, preventing compensatory ocular torsion and erroneous influence on SVV result. OBJECTIVE: To analyze the influence of somatosensory inputs caused by a NB on the SVV. METHOD: Thirty healthy volunteers performed static and dynamic SVV: six measures with and six without the NB. RESULTS: The mean values for static SVV were -0.075º±1.15º without NB and -0.372º±1.21º with NB. For dynamic SVV in clockwise direction were 1.73º±2.31º without NB and 1.53º±1.80º with NB. For dynamic SVV in counterclockwise direction was -1.50º±2.44º without NB and -1.11º±2.46º with NB. Differences between measurements with and without the NB were not statistically significant. CONCLUSION: Although the neck has many sensory receptors, the use of a NB does not provide sufficient afferent input to change healthy subjects' perception of visual verticality.

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Subjective Visual Vertical during Caloric Stimulation in Healthy Subjects: Implications to Research and Neurorehabilitation

Rehabilitation Research and Practice ◽

10.1155/2015/367695 ◽

2015 ◽

Vol 2015 ◽

pp. 1-4 ◽

Cited By ~ 2

Author(s):

Martha Funabashi ◽

Aline I. Flores ◽

Amanda Vicentino ◽

Camila G. C. Barros ◽

Octavio M. Pontes-Neto ◽

...

Keyword(s):

Healthy Subjects ◽

Cognitive Strategies ◽

Semicircular Canals ◽

Subjective Visual Vertical ◽

Caloric Stimulation ◽

Neurologic Disorders ◽

Significant Difference ◽

Sensitive Tool ◽

Visual Vertical ◽

The Mean

Background. The subjective visual vertical (SVV) is a perception often impaired in patients with neurologic disorders and is considered a sensitive tool to detect otolithic dysfunctions. However, it remains unclear whether the semicircular canals (SCCs) are also involved in the visual vertical perception.Objective. The aim of this study was to analyze the influence of horizontal SCCs on SVV by caloric stimulation in healthy subjects.Methods. SVV was performed before and during the ice-cold caloric stimulation (4°C, right ear) in 30 healthy subjects.Results. The mean SVV tilts before and during the caloric stimulation were 0.31° ± 0.39 and −0.28° ± 0.40, respectively. There was no significant difference between the mean SVV tilts before and during stimulationp=0.113.Conclusion. These results suggest that horizontal SCCs do not influence SVV. Therefore, investigations and rehabilitation approaches for SVV misperceptions should be focused on otolithic and cognitive strategies.

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Quantitative studies of the reactions to horizontal angular accelerations in axolotls. I. The head-turning reflexes of normal animals

Journal of Experimental Biology ◽

10.1242/jeb.66.1.1 ◽

1977 ◽

Vol 66 (1) ◽

pp. 1-14

Author(s):

K. Brandle

Keyword(s):

Stimulus Intensity ◽

Time Course ◽

Maximum Velocity ◽

Afferent Input ◽

Head Turning ◽

Mean Values ◽

Quantitative Studies ◽

The Mean ◽

Negative Exponential ◽

Total Angle

1. Artifically metamorphosed axolotls were exposed to both brief (impulse) and long-lasting horizontal angular accelerations on a turn-table. The animals responded with a head-turning reaction. 2. The general course of the reaction to impulse acceleration was independent of stimulus intensity. The velocity of the head movement first increased to a maximum exponentially and then decreased in a negative exponential manner. Stimulus intensity had a linear relationship to the mean maximum velocity and mean total angle covered by head-turning. The average velocity-time curves at various stimulus intensities differed only by a velocity factor. 3. During long-lasting constant accelerations the velocity of the head-turning increased to a maximum velocity in a sigmoid time-course and then decreased, first to a constant velocity, and then further. Mean values of the maximum velocity were correlated linearly with the stimulus intensity. 4. It was concluded that the head-turning reflexes in axolotls do not agree with the accepted movements of the vertebrate cupula and therefore are not a simple ‘copy’ of the afferent input. It is also suggested that the reaction threshold differes from that for the labyrinthine input.

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Effects of food and sucralfate on a single oral dose of 500 milligrams of levofloxacin in healthy subjects.

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.41.10.2196 ◽

1997 ◽

Vol 41 (10) ◽

pp. 2196-2200 ◽

Cited By ~ 45

Author(s):

L J Lee ◽

B Hafkin ◽

I D Lee ◽

J Hoh ◽

R Dix

Keyword(s):

Oral Dose ◽

Healthy Subjects ◽

High Fat ◽

Time Curve ◽

Mean Values ◽

Treatment Groups ◽

The Mean ◽

The Individual ◽

Individual Profiles ◽

Fat Meal

The effects of food and sucralfate on the pharmacokinetics of levofloxacin following the administration of a single 500-mg oral dose were investigated in a randomized, three-way crossover study with young healthy subjects (12 males and 12 females). Levofloxacin was administered under three conditions: fasting, fed (immediately after a standardized high-fat breakfast), and fasting with sucralfate given 2 h following the administration of levofloxacin. The concentrations of levofloxacin in plasma and urine were determined by high-pressure liquid chromatography. By noncompartmental methods, the maximum concentration of drug in serum (Cmax), the time to Cmax (Tmax), the area under the concentration-time curve (AUC), half-life (t1/2), clearance (CL/F), renal clearance (CLR), and cumulative amount of levofloxacin in urine (Ae) were estimated. The individual profiles of the drug concentration in plasma showed little difference among the three treatments. The only consistent effect of the coadministration of levofloxacin with a high-fat meal for most subjects was that levofloxacin absorption was delayed and Cmax was slightly reduced (Tmax, 1.0 and 2.0 h for fasting and fed conditions, respectively [P = 0.002]; Cmax, 5.9 +/- 1.3 and 5.1 +/- 0.9 microg/ml [90% confidence interval = 0.79 to 0.94] for fasting and fed conditions, respectively). Sucralfate, which was administered 2 h after the administration of levofloxacin, appeared to have no effect on levofloxacin's disposition compared with that under the fasting condition. Mean values of Cmax and AUC from time zero to infinity were 6.7 +/- 3.2 microg/ml and 47.9 +/- 8.4 microg x h/ml, respectively, following the administration of sucralfate compared to values of 5.9 +/- 1.3 microg/ml and 50.5 +/- 8.1 microg x h/ml, respectively, under fasting conditions. The mean t1/2, CL/F, CLR, and Ae values were similar among all three treatment groups. In conclusion, the absorption of levofloxacin was slightly delayed by food, although the overall bioavailability of levofloxacin following a high-fat meal was not altered. Finally, sucralfate did not alter the disposition of levofloxacin when sucralfate was given 2 h after the administration of the antibacterial agent, thus preventing a potential drug-drug interaction.

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Within-subject and between-subject biological variation estimates of 21 hematological parameters in 30 healthy subjects

Clinical Chemistry and Laboratory Medicine (CCLM) ◽

10.1515/cclm-2017-1155 ◽

2018 ◽

Vol 56 (8) ◽

pp. 1309-1318 ◽

Cited By ~ 26

Author(s):

Abdurrahman Coşkun ◽

Anna Carobene ◽

Meltem Kilercik ◽

Mustafa Serteser ◽

Sverre Sandberg ◽

...

Keyword(s):

Healthy Subjects ◽

Complete Blood Count ◽

Hematological Parameters ◽

Hemoglobin Concentration ◽

Biological Variation ◽

Mean Corpuscular Hemoglobin ◽

Mean Values ◽

Performance Specifications ◽

The Mean ◽

Variance Homogeneity

Abstract Background: The complete blood count (CBC) is used to evaluate health status in the contexts of various clinical situations such as anemia, infection, inflammation, trauma, malignancies, etc. To ensure safe clinical application of the CBC, reliable biological variation (BV) data are required. The study aim was to define the BVs of CBC parameters employing a strict protocol. Methods: Blood samples, drawn from 30 healthy subjects (17 females, 13 males) once weekly for 10 weeks, were analyzed using a Sysmex XN 3000 instrument. The data were assessed for normality, trends, outliers and variance homogeneity prior to coefficient of variation (CV)-analysis of variance (ANOVA). Sex-stratified within-subject (CVI) and between-subjects (CVG) BV estimates were determined for 21 CBC parameters. Results: For leukocyte parameters, with the exception of lymphocytes and basophils, significant differences were found between female/male CVI estimates. The mean values of all erythrocyte-, reticulocyte- and platelet parameters differed significantly between the sexes, except for mean corpuscular hemoglobin concentration, mean corpuscular volume and platelet numbers. Most CVI and CVG estimates appear to be lower than those previously published. Conclusions: Our study, based on a rigorous protocol, provides updated and more stringent BV estimates for CBC parameters. Sex stratification of data is necessary when exploring the significance of changes in consecutive results and when setting analytical performance specifications.

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The Circadian Rhythm of Copeptin, the C-Terminal Portion of Arginine Vasopressin

Journal of Biomarkers ◽

10.1155/2017/4737082 ◽

2017 ◽

Vol 2017 ◽

pp. 1-5 ◽

Cited By ~ 7

Author(s):

Svetlana Beglinger ◽

Jürgen Drewe ◽

Mirjam Christ-Crain

Keyword(s):

Circadian Rhythm ◽

Healthy Subjects ◽

Prospective Observational Study ◽

Diagnostic Marker ◽

Early Morning ◽

Fasting Period ◽

Mean Values ◽

The Mean ◽

Salt Homeostasis ◽

Minor Extent

Background. Several studies have investigated copeptin as a prognostic marker of different acute diseases and as a diagnostic marker in disorders of water and salt homeostasis. However, no data of the normal circadian rhythm of copeptin in healthy subjects are available. Aim. To investigate the circadian rhythm of copeptin in healthy subjects under standardized conditions. Methods. 19 healthy volunteers aged 18 to 53 years, male and female, were studied in a prospective observational study. In all 19 participants, blood samples for copeptin were taken in regular intervals of 30 minutes for 24 hours after a fasting period of minimum 8 hours. Results. The mean values of copeptin showed a circadian rhythm, similar to that described for AVP release, with a trend towards higher levels (5.9±1 pmol/L) at night and early morning between 4 am and 6 am and lowest levels (2.3±0.2 pmol/L) in the late afternoon between 5 pm and 7 pm. This finding was only observed in individuals with initial higher copeptin levels, whereas in individuals with lower basal copeptin levels no circadian rhythm was observed. Conclusion. There is evidence for a circadian rhythm in copeptin release during 24 hours, however, of minor extent. These findings suggest that copeptin levels can be determined irrespectively of the time of the day.

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Variability of resting respiratory drive and timing in healthy subjects

Journal of Applied Physiology ◽

10.1152/jappl.1988.65.1.309 ◽

1988 ◽

Vol 65 (1) ◽

pp. 309-317 ◽

Cited By ~ 144

Author(s):

M. J. Tobin ◽

M. J. Mador ◽

S. M. Guenther ◽

R. F. Lodato ◽

M. A. Sackner

Keyword(s):

Standard Deviation ◽

Healthy Subjects ◽

Breathing Pattern ◽

Respiratory Drive ◽

Inspiratory Time ◽

Mean Values ◽

Coefficients Of Variation ◽

The Mean ◽

Older Subjects ◽

Young Subjects

Studies of breathing pattern have focused primarily on changes in the mean values of the breathing pattern components, whereas there has been minimal investigation of breath-to-breath variability, which should provide information on the constancy with which respiration is controlled. In this study we examined the variability of breathing pattern both on a breath-to-breath and day-to-day basis by calculating the coefficient of variation (i.e., the standard deviation expressed as a percentage of the mean). By examining breath-to-breath data, we found that the coefficients of variation of tidal volume (VT) and fractional inspiratory time (TI/TT, an index of timing) obtained with an inductive plethysmograph and spirometer were within 1% of each other. Examination of breath-to-breath variability in breathing pattern over a 15-min period in 65 subjects revealed large coefficients of variation, indicating the need to base calculations on a relatively large number of breaths. Less breath-to-breath variability was observed in respiratory frequency [f, 20.8 +/- 11.5% (SD)] and TI/TT (17.9 +/- 6.5%) than in VT (33 +/- 14.9%) and mean inspiratory flow (VT/TI, an index of drive; 31.6 +/- 12.6%; P less than 0.0001). Older subjects (60-81 yr) displayed greater breath-to-breath variability than young subjects (21-50 yr). Use of a mouthpiece did not affect the degree of variability.(ABSTRACT TRUNCATED AT 250 WORDS)

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Influence of Fasting followed by Acute Water Ingestion on Subfoveal Choroidal Thickness in Eyes of Healthy Subjects

Ophthalmology Point of Care ◽

10.5301/oapoc.0000013 ◽

2017 ◽

Vol 1 (1) ◽

pp. oapoc.0000013

Author(s):

Rocio Blanco-Garavito ◽

Polina Astroz ◽

Salomon Yves Cohen ◽

Eric H. Souied

Keyword(s):

Healthy Volunteers ◽

Healthy Subjects ◽

Choroidal Thickness ◽

Enhanced Depth Imaging ◽

Hydration Status ◽

Subfoveal Choroidal Thickness ◽

Water Ingestion ◽

Case Series Study ◽

Significant Difference ◽

The Mean

Purpose To investigate the influence of at least 12 hours of fasting followed by acute water ingestion on macular choroidal thickness in eyes of healthy subjects. Methods Prospective case series study including healthy volunteers from April 1, 2015 to May 31, 2015. Macular choroidal thickness was measured on enhanced depth imaging optical coherence tomography (EDI-OCT) and on swept-source (SS)-OCT after 12 hours of fasting, and 60 minutes after acute water ingestion (750 mL in 5 minutes). Results A total of 52 eyes of 26 healthy volunteers were included in this study. The mean age for participants was 32 years old. After 12 hours of fasting, the mean (±SD) subfoveal choroidal thickness was 335.43 (±104.82) μm on EDI-OCT and 286.16 (±80.32) μm on SS-OCT. The mean (±SD) subfoveal choroidal thickness after acute water intake was 352.32 (±120.36) μm and 290.5 (±85.86) μm, respectively. There was no significant difference between the mean subfoveal thickness at baseline and 60 minutes after acute water ingestion for any of the choroidal imaging techniques (p = 0.1386 for EDI-OCT and p = 0.0659 for SS-OCT). Conclusions These results suggest that choroidal circulation can physiologically quickly adapt to systemic vascular changes in healthy eyes. Choroidal thickness did not depend upon the hydration status for the subjects participating in this study.

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Discriminant Analysis of the Coordinated Work Indicators of the Heart and Blood Vessels in Health and Disease

Biomeditsina ◽

10.33647/2074-5982-17-2-8-21 ◽

2021 ◽

Vol 17 (2) ◽

pp. 8-21

Author(s):

N. N. Karkischenko ◽

D. B. Chaivanov ◽

Y. A. Chudina ◽

A. A. Nikolaev ◽

A. A. Vartanov

Keyword(s):

Healthy Volunteers ◽

Pulse Wave ◽

Mean Values ◽

Trend Model ◽

Wave Duration ◽

Straight Line ◽

Coeffi Cients ◽

Health And Disease ◽

The Mean ◽

Apparently Healthy

A discriminant method was proposed for modeling and quantifying the consistency of regulatory mechanisms in the cardiovascular system (CVS) of apparently healthy volunteers and those suffering from circulatory disorders associated with cervical spine osteochondrosis (OCS) and somatoform autonomic dysfunction (SAD). The congruence of the parameters of ECG intervalometry (DCI) and pulse wave duration (PWD) according to the volunteers’ photoplethysmograms (PPG) was established by calculating the disparity measure and deviations from the mean values using the coeffi cients of displacement, slope of the approximating straight line, as well as by comparing the reliability and correlation of the trend model with the initial data. We discovered gross violations of congruence in the work of efferent and afferent regulatory CVS mechanisms, mismatch and decrease in comparison with the norm of DCI and PWD, a signifi cant decrease in their approximation in the SAD volunteers. In volunteers with OCS, deviations in DCI and PWD from their mean values are much lower than in those with SAD, being inferior compared to healthy volunteers. Similar to SAD, these patients are inferior to healthy volunteers in terms of the disparity measure.

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Ultrasound Assessment of Diaphragm Thickness and Thickening: Reference Values and Limits of Normality When in a Seated Position

Frontiers in Medicine ◽

10.3389/fmed.2021.742703 ◽

2021 ◽

Vol 8 ◽

Author(s):

Alain Boussuges ◽

Sarah Rives ◽

Julie Finance ◽

Guillaume Chaumet ◽

Nicolas Vallée ◽

...

Keyword(s):

Healthy Volunteers ◽

Normal Values ◽

Deep Breathing ◽

Diaphragm Thickness ◽

Quiet Breathing ◽

Men And Women ◽

Mean Values ◽

Diaphragmatic Function ◽

The Mean ◽

The Right

Background: Diagnosing diaphragm dysfunction in the absence of complete paralysis remains difficult. The aim of the present study was to assess the normal values of the thickness and the inspiratory thickening of both hemidiaphragms as measured by ultrasonography in healthy volunteers while in a seated position.Methods: Healthy volunteers with a normal pulmonary function test were recruited. The diaphragmatic thickness was measured on both sides at the zone of apposition of the diaphragm to the rib cage during quiet breathing at end-expiration, end-inspiration, and after maximal inspiration. The thickening ratio, the thickening fraction, and the thickness at end-inspiration divided by the thickness at deep breathing were determined. The mean values and the lower and upper limits of normal were determined for men and women.Results: 200 healthy volunteers (100 men and 100 women) were included in the study. The statistical analysis revealed that women had a thinner hemidiaphragm than men on both sides and at the various breathing times studied. The lower limit of normality of the diaphragm thickness measured at end-expiration was estimated to be 1.3 mm in men and 1.1 mm in women, on both sides. The thickening fraction did not differ significantly between men and women. In men, it ranged from 60 to 260% on the left side and from 57 to 200% on the right side. In women, it ranged from 58 to 264% on the left side and from 60 to 229% on the right side. The lower limits of normality of the thickening fraction were determined to be 40 and 39% in men and 39 and 48% in women for the right and left hemidiaphragms, respectively. The upper limit for normal of the mean of both sides of the ratio thickness at end-inspiration divided by the thickness at deep breathing was determined to be 0.78 in women and 0.79 in men.Conclusion: The normal values of thickness and the indexes of diaphragmatic function should help clinicians with detecting diaphragm atrophy and dysfunction.

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Impaired Subjective Visual Vertical and Increased Visual Dependence in Older Adults With Falls

Frontiers in Aging Neuroscience ◽

10.3389/fnagi.2021.667608 ◽

2021 ◽

Vol 13 ◽

Author(s):

Milda Totilienė ◽

Virgilijus Uloza ◽

Vita Lesauskaitė ◽

Gytė Damulevičienė ◽

Rima Kregždytė ◽

...

Keyword(s):

Older Adults ◽

Odds Ratio ◽

Assessment Tools ◽

Subjective Visual Vertical ◽

Risk Of Falling ◽

Falls Risk ◽

Visual Vertical ◽

The Mean ◽

Visual Dependence ◽

Tinetti Test

Aging affects the vestibular system and may disturb the perception of verticality and lead to increased visual dependence (VD). Studies have identified that abnormal upright perception influences the risk of falling. The aim of our study was to evaluate subjective visual vertical (SVV) and VD using a mobile virtual reality-based system for SVV assessment (VIRVEST) in older adults with falls and evaluate its relationship with clinical balance assessment tools, dizziness, mental state, and depression level. This study included 37 adults >65 years who experienced falls and 40 non-faller age-matched controls. Three tests were performed using the VIRVEST system: a static SVV, dynamic SVV with clockwise and counter-clockwise background stimulus motion. VD was calculated as the mean of absolute values of the rod tilt from each trial of dynamic SVV minus the mean static SVV rod tilt. Older adults who experienced falls manifested significantly larger biases in static SVV (p = 0.012), dynamic SVV (p < 0.001), and VD (p = 0.014) than controls. The increase in static SVV (odds ratio = 1.365, p = 0.023), dynamic SVV (odds ratio = 1.623, p < 0.001) and VD (odds ratio = 1.460, p = 0.010) tilt by one degree significantly related to falls risk in the faller group. Fallers who had a high risk of falling according to the Tinetti test exhibited significantly higher tilts of dynamic SVV than those who had a low or medium risk (p = 0.037). In the faller group, the increase of the dynamic SVV tilt by one degree was significantly related to falls risk according to the Tinetti test (odds ratio = 1.356, p = 0.049). SVV errors, particularly with the dynamic SVV test (i.e., greater VD) were associated with an increased risk of falling in the faller group. The VIRVEST system may be applicable in clinical settings for SVV testing and predicting falls in older adults.

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