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Biomedical subjects

C Wall

Publications and source records attributed to C Wall.

At least 19 recordsLinked to original sources
PubMed2005

Development of a psychometrically valid and reliable sports nutrition knowledge questionnaire.

The present range of sports nutrition knowledge questionnaires have inadequate psychometric validation, and few are up to date in a rapidly changing discipline. The purpose of this study was to design a sports nutrition questionnaire that satisfied acceptable psychometric criteria of validity (content and construct) and reliability (test-retest). The questionnaire was designed by an expert panel of six sports dietitians and distributed to five groups, selected for their expected variation in sports nutrition knowledge. Dietitians, university business staff and nutrition students received questionnaires via e-mail. The response rates obtained were 21.3% (n = 49), 34.4% (n = 33), and 72.0% (n = 18), respectively. University business and fitness students completed questionnaires during class time. Response rates were 52.3% (n = 23) and 75.4% (n = 49), respectively. The questionnaire was administered a second time to the business staff and the dietitians to assess test-retest reliability. Two methods were used: 1, Pearson's product-moment correlation; and 2, a percentage calculation of questions answered in an identical manner on both test occasions. Reliability was acceptable with Method 1 yielding acceptable values (r = 0.74-0.93), aside from the fluid sub-category (r = 0.52). Method 2 showed good test-retest concordance with 81.2% duplication of responses of all questions. Construct validity was high, as indicated by significant mean knowledge score differences between the groups (p = 0.0001). Dietitians and nutrition students achieved significantly greater mean scores than the remaining groups. The findings of this study indicate that the questionnaire is suitably valid and reliable to be used in research and practice to determine sports nutrition knowledge.

Dietetics↗
PubMed2005

Randomized, double-blind comparison of growth in infants receiving goat milk formula versus cow milk infant formula.

OBJECTIVE: To compare growth of infants fed goat milk infant formula (GMF) or cow milk infant formula (CMF) and to compare tolerability and safety of the two formulas. METHODS: The study was conducted in Auckland, New Zealand. This was a double-blind randomized controlled trial. Newborn term infants were randomized within 72 h of birth to GMF or CMF. Milk formula powder in single serve sachets were reconstituted and fed to infants from trial commencement until age 168 days. No other formula given from randomization until age 168 days. Infant weight, length and head circumference were measured at birth and age 14, 28, 56, 84, 112, 140 and 168 days. Bowel motion frequency and consistency, sleeping and crying patterns and adverse events were also measured. RESULTS: Seventy-two infants were randomized, 36 each to GMF or CMF, with 62 infants completing the intervention. At enrollment the average weight of infants in the GMF group (mean +/- SD) was 3.33 +/- 0.43 kg and in the CMF group 3.43 +/- 0.47 kg; and at study completion 8.07 +/- 0.90 kg (GMF) and 7.87 +/- 0.99 kg (CMF). The difference in average weight gain over the study period for the GMF group versus the CMF group was not significant (+309 g; 95% CI = -49 to +668, P = 0.09). Median daily bowel motion frequency was greater in the GMF group than the CMF group (2.4 vs 1.7, P = 0.01). There were no group differences in bowel motion consistency, duration of crying, ease of settling, or frequency of adverse events. CONCLUSION: Growth of infants fed GMF is not different to that of infants-fed CMF.

Animals↗
PubMed2005

Control of sway using vibrotactile feedback of body tilt in patients with moderate and severe postural control deficits.

We evaluated the effect of the vibrotactile display of body tilt upon the postural stability of vestibulopathic subjects during standing. Two groups were studied: those with moderate and with severe deficits as defined by postural stability test scores. They were studied under conditions of distorted sensory input, and during anterior-posterior perturbations. Seventeen subjects, with uni- or bilateral vestibular deficits, as determined by electronystagmography and vertical axis rotation, were tested using Equitest computerized dynamic posturography (CDP). Based on their performance on the CDP they were divided into two groups having either moderate (nine subjects) or severe (eight subjects) postural control deficits. Their anterior-posterior (A/P) body motion at the waist was measured with a micromechanical rate gyroscope and a linear accelerometer. The resulting tilt estimate was displayed by a vibrotactile array attached to the torso. The vibration served as a tilt feedback to the subject. The subject's performance was evaluated using the root-mean-square (RMS) of both the A/P body motion and center-of-pressure (CoP) estimates. Sensory distortions were introduced using the Equitest Sensory Organization Tests (SOT). These tests are designed to distort A/P sensory inputs while standing. The SOT 5 distorts proprioceptive information about ankle joint movement, while the subject stands eyes-closed on a moving support platform that measures foot pressure. The SOT 6 adds distorted visual information about body movement instead of testing with eyes closed. Perturbations were introduced using the Equitest Motor Control Tests (MCT). These move the support platform forward or backward with small, medium and large displacements in the horizontal plane while measuring subjects' foot pressure responses. We used the medium and large backward tests. Vibrotactile display of body tilt reduced the subjects' A/P sway and improved their balance. The finding was more evident for those subjects with severe deficits than those moderate ones. This trend was found for both SOT 5 and 6, as well as the medium and large MCT. Additionally, during the MCT, the peak deflection and mean recovery time also decreased significantly.

Adaptation, Physiological↗
PubMed2001

Diagnosis of Duchenne dystrophy by enhanced detection of small mutations.

OBJECTIVE: To determine whether detection of small mutations of the dystrophin gene can be increased using an enhanced method of single-strand conformation polymorphism analysis. BACKGROUND: Usual methods of DNA analysis for Duchenne dystrophy cannot identify mutations in one-third of cases. Muscle biopsy, with its inherent risks and added liability for patients with Duchenne dystrophy, becomes the sole method of diagnosis. Even with a tissue diagnosis of dystrophin deficiency, many families are excluded from carrier detection and prenatal diagnosis. METHODS: Genomic DNA from a cohort of 93 patients with Duchenne dystrophy without identifiable gene mutations was screened for mutations. In each case, 22 kilobases of genomic DNA were scanned, including all 79 exons of the dystrophin gene, adjacent intronic regions, and six alternative exons 1. RESULTS: Sixty-eight (73%) had small mutations, including 34 nonsense mutations, 27 microdeletions and insertions, and 7 splice site mutations. No missense mutations were found. One nonsense mutation in exon 59 was detected in four patients. Most mutations were new; 54 of 62 different small mutations have not been reported. Mutations were found throughout the gene: 24% in the first quartile, 31% in the second, 16% in the third, and 29% in the fourth. CONCLUSIONS: A highly sensitive single-strand conformation polymorphism method substantially increased detection of small dystrophin gene mutations and made it possible to diagnose approximately 90% of patients with Duchenne dystrophy by DNA analysis. These findings, combined with cost savings and safety issues, provide compelling reasons to consider DNA analysis as the initial diagnostic test for the suspected dystrophin-deficient patient.

Adolescent↗
PubMed2001

Balance prosthesis based on micromechanical sensors using vibrotactile feedback of tilt.

A prototype balance prosthesis has been made using miniature, high-performance inertial sensors to measure lateral head tilt and vibrotactile elements mounted on the body to display head tilt to the user. The device has been used to study the feasibility of providing artificial feedback of head tilt to reduce postural sway during quiet standing using six healthy subjects. Two vibrotactile display schemes were used: one in which the individual vibrating elements, called tactors, were placed on the shoulders (shoulder tactors); another in which columns of tactors were placed on the right and left sides of the trunk (side tactors). Root-mean-square head-tilt angle (Tilt) and center of pressure displacement (Sway) were measured for normal subjects standing in a semi-tandem Romberg position with eyes closed, under four conditions: no balance aids; shoulder tactors; side tactors; and light touch. Compared with no balance aids, the side tactors significantly reduced Tilt (35%) and Sway (33%). Shoulder tactors also significantly reduced Tilt (44%) and Sway (17%). Compared with tactors, light touch resulted in less Sway, but more Tilt. The results suggest that healthy normal subjects can reduce their lateral postural sway using head tilt information as provided by a vibrotactile display. Thus, further testing with balance-impaired subjects is now warranted.

Adult↗
PubMed2001

Application of multivariate statistics to vestibular testing: discriminating between Menière's disease and migraine associated dizziness.

Menière's disease (MD) and migraine associated dizziness (MAD) are two disorders that can have similar symptomatologies, but differ vastly in treatment. Vestibular testing is sometimes used to help differentiate between these disorders, but the inefficiency of a human interpreter analyzing a multitude of variables independently decreases its utility. Our hypothesis was that we could objectively discriminate between patients with MD and those with MAD using select variables from the vestibular test battery. Sinusoidal harmonic acceleration test variables were reduced to three vestibulo-ocular reflex physiologic parameters: gain, time constant, and asymmetry. A combination of these parameters plus a measurement of reduced vestibular response from caloric testing allowed us to achieve a joint classification rate of 91%, independent quadratic classification algorithm. Data from posturography were not useful for this type of differentiation. Overall, our classification function can be used as an unbiased assistant to discriminate between MD and MAD and gave us insight into the pathophysiologic differences between the two disorders.

Adolescent↗
PubMed2001

The human oculomotor response to simultaneous visual and physical movements at two different frequencies.

In order to investigate interactions in the visual and vestibular systems' oculomotor response to linear movement, we developed a two-frequency stimulation technique. Thirteen subjects lay on their backs and were oscillated sinusoidally along their z-axes at between 0.31 and 0.81 Hz. During the oscillation subjects viewed a large, high-contrast, visual pattern oscillating in the same direction as the physical motion but at a different, non-harmonically related frequency. The evoked eye movements were measured by video-oculography and spectrally analysed. We found significant signal level at the sum and difference frequencies as well as at other frequencies not present in either stimulus. The emergence of new frequencies indicates non-linear processing consistent with an agreement-detector system that have previously proposed.

Eye Movements↗
PubMed2000

Canadian National Breast Screening Study-2: 13-year results of a randomized trial in women aged 50-59 years.

BACKGROUND: Screening for breast cancer with mammography in women aged 50 years or more has been shown to reduce mortality from breast cancer. However, the extent to which mammography contributes to the reduction of mortality in women who also undergo physical examination of the breasts is not known. This study was designed to compare breast cancer mortality following annual screening consisting of two-view mammography and physical examination of the breasts with mortality following annual screening by physical examination only. Breast self-examination was taught to all participants. METHODS: This trial randomly and individually assigned 39 405 women aged 50-59 years, recruited from January 1980 through March 1985, to one of the study arms. The women were followed by record linkage with the Canadian National Cancer Registry and National Mortality Database to December 31, 1993, and by active follow-up of breast cancer patients to June 30, 1996. RESULTS: Randomization achieved virtually equal distribution of demographic and breast cancer risk variables. At the first annual screen, 21% of the cancers found by mammography alone (in the mammography plus physical examination group) were 20 mm or more in size compared with 46% of those found by physical examination in the mammography plus physical examination group and 56% in the physical examination-only group. The corresponding percentages for screens 2-5 were 10%, 42%, and 50%, respectively. Screening detected 267 invasive breast cancers in the mammography plus physical examination group compared with 148 in the physical examination-only group. By December 31, 1993, 622 invasive and 71 in situ breast carcinomas were ascertained in the mammography plus physical examination group, and 610 and 16 were ascertained in the physical examination-only group. At 13-year follow-up, with 107 and 105 deaths from breast cancer in the respective groups, the cumulative rate ratio was 1.02 (95% confidence interval = 0.78-1.33). CONCLUSION: In women aged 50-59 years, the addition of annual mammography screening to physical examination has no impact on breast cancer mortality.

Breast Neoplasms↗
PubMed2000

Interlaboratory variability of rotational chair test results II: analysis of simulated data.

Standardization of rotational chair testing across laboratories has not been achieved because of differences in test protocol and analysis algorithms. The Interlaboratory Rotational Chair Study Group was formed to investigate these differences. Its first study demonstrated significant variability in calculated results using actual patient data files. No estimation of accuracy could be made, however, because the "true" values of response parameters were unknown. In this study we used simulated "patient" data files to further explore the differences among analysis algorithms. We found a high degree of agreement and accuracy across laboratories using automated analysis of high signal-to-noise/low-artifact data for gain, phase, and asymmetry. Variability increased significantly for the lower signal-to-noise ratio/higher artifact files. Operator intervention generally improved accuracy and decreased variability, but there were cases in which operator intervention reduced accuracy.

Computer Simulation↗
PubMed2000

Temporal bone studies of the human peripheral vestibular system. Normative vestibular hair cell data.

Quantitative studies of the vestibular system with serially sectioned human temporal bones have been limited because of difficulty in distinguishing hair cells from supporting cells and type I from type II hair cells. In addition, there is only a limited amount of normative data available regarding vestibular hair cell counts in humans. In this study, archival temporal bone sections were examined by Nomarski (differential interference contrast) microscopy, which permitted visualization of the cuticular plate and stereociliary bundle so as to allow unambiguous identification of hair cells. The density of type I, type II, and total numbers of vestibular hair cells in each of the 5 sense organs was determined in a set of 67 normal temporal bones that ranged from birth through 100 years of age. The mean total densities at birth were 76 to 79 cells per 0.01 mm2 in the cristae, 68 cells per 0.01 mm2 in the utricle, and 61 cells per 0.01 mm2 in the saccule. The ratio of type I to type II hair cells at birth was 2.4:1 in the cristae and 1.3:1 in the maculae. There was a highly significant age-related decline in all sense organs for total, type I, and type II hair cell densities that was best fit by a linear regression model. The cristae lost type I cells with advancing age at a significantly greater rate than the maculae, whereas age-related losses for type II cells occurred at the same rate for all 5 sense organs. Hair cell densities in the cristae were significantly higher at the periphery than at the center. There were no significant sex or interaural differences for any of the counts. Mathematical models were developed to calculate the mean and 95% prediction intervals for the total, type I, and type II hair cell densities in each sense organ on the basis of age. There was overall good agreement between the hair cell densities determined in this study and those reported by others using surface preparation techniques. Our data and related models will serve as a normative database that will be useful for comparison to counts made from subjects with known vestibular disorders.

Adolescent↗
PubMed2000

Temporal bone studies of the human peripheral vestibular system. Normative Scarpa's ganglion cell data.

Scarpa's ganglion cell counts were performed in 106 serially sectioned, normal human temporal bones from 75 individuals. Of these 106 bones, 15 were from neonates less than 30 days old, 14 were from infants between the ages of 1 and 12 months, and the remainder were distributed throughout each decade of life, with sample sizes ranging from 4 to 10 per decade. All temporal bones had to meet 2 criteria: no symptoms or signs of inner ear disease except for presbycusis in the medical case history and no abnormality in the inner ear on light microscopy. The total ganglion cell counts declined significantly with age at an average rate of 57 cells per year. The age-related decline was significantly greater in the superior division than in the inferior division. There was also a significant sex effect, independent of age: for any age, the count in men averaged 1,526 cells higher than in women. There was no significant interaural difference. Mathematical models were developed to compute the mean and 95% prediction intervals for Scarpa's ganglion cell counts in terms of age and sex parameters. The counts and models will serve as a normative database against which to compare counts made in temporal bones from subjects with known vestibular disorders.

Adolescent↗
PubMed2000

Temporal bone studies of the human peripheral vestibular system. Aminoglycoside ototoxicity.

Quantitative assessments of vestibular hair cells and Scarpa's ganglion cells were performed on 17 temporal bones from 10 individuals who had well-documented clinical evidence of aminoglycoside ototoxicity (streptomycin, kanamycin, and neomycin). Assessment of vestibular hair cells was performed by Nomarski (differential interference contrast) microscopy. Hair cell counts were expressed as densities (number of cells per 0.01 mm2 surface area of the sensory epithelium). The results were compared with age-matched normal data. Streptomycin caused a significant loss of both type I and type II hair cells in all 5 vestibular sense organs. In comparing the ototoxic effect on type I versus type II hair cells, there was greater type I hair cell loss for all 3 cristae, but not for the maculae. The vestibular ototoxic effects of kanamycin appeared to be similar to those of streptomycin, but the small sample size precluded definitive conclusions from being made. Neomycin did not cause loss of vestibular hair cells. Within the limits of this study (maximum postototoxicity survival time of 12 months), there was no significant loss of Scarpa's ganglion cells for any of the 3 drugs. The findings have implications in several clinical areas, including the correlation of vestibular test results to pathological findings, the rehabilitation of patients with vestibular ototoxicity, the use of aminoglycosides to treat Meniere's disease, and the development of a vestibular prosthesis.

Adult↗
PubMed2000

Temporal bone studies of the human peripheral vestibular system. Meniere's disease.

Quantitative assessments of vestibular hair cells and Scarpa's ganglion cells were performed on temporal bones from 24 patients with well-documented Meniere's disease. Of these, 18 had unilateral disease and 6 had bilateral disease. Vestibular hair cell counts were made in each of the 5 sense organs by Nomarski (differential interference contrast) microscopy. Hair cell counts were expressed as densities: number of cells per 0.01 mm2 surface area of the sensory epithelium. The results were compared with age- and sex-matched normal data. The type I hair cell densities for all vestibular sense organs were within the range for normative data. On the other hand, there was a significant loss (p < .01) of type II hair cells for all 3 cristae and both maculae. There was also a significant loss of Scarpa's ganglion cells (p < .001) when compared with normative data. The findings indicate a selective loss of type II hair cells and Scarpa's ganglion cells in Meniere's disease. These new observations have implications regarding the pathophysiological mechanism and clinical manifestations of Meniere's disease.

Adult↗
PubMed1999

Mechanisms of alcohol-induced hepatotoxicity: studies in rats.

Alcohol treatment results in increases in the release of endotoxin from gut bacteria and membrane permeability of the gut to endotoxin, or both. Females are more sensitive to these changes. Elevated levels of endotoxin activate Kupffer cells to release substances such as eicosanoids, TNF-alpha and free radicals. Prostaglandins increase oxygen uptake and most likely are responsible for the hypermetabolic state in the liver. The increase in oxygen demand leads to hypoxia in the liver, and on reperfusion, alpha-hydroxyethyl free radicals are formed which lead to tissue damage in oxygen-poor pericentral regions of the liver lobule.

Animals↗
PubMed1999

Feeding problems in infants with gastro-oesophageal reflux disease: a controlled study.

OBJECTIVE: Gastro-oesophageal reflux disease (GORD) in infants is commonly associated with feeding problems but has not been subject to systematic controlled study. We evaluated feeding, dietary, behavioural data obtained from systematic objective studies of six-month old infants with and without GORD. METHODS: Infants with GORD (defined by 24-h pH monitoring, n = 20), and age, gender, gestation, and socio-economic matched healthy infants (n = 20) had standardised assessments of dietary intake, oromotor function by videoanalysis (Feeding Assessment Schedule, FAS), and infant feeding behaviour by Testers and Maternal Ratings (TRIB and MRIB). Videofluoroscopic analyses of swallowing was undertaken in 11/20 GORD infants and analysed by standardised paediatric check list. RESULTS: Compared with control data: GORD infants had significantly lower energy intakes; the FAS showed GORD infants to have significantly fewer adaptive skills and readiness behaviour for solids, significantly more food refusal and food loss; the TRIB showed GORD infants to be significantly more demanding and difficult with feeds; and the MRIB revealed that mothers of GORD infants had significantly more negative feelings, significantly less enjoyment of feeds, and reported significantly more crying behaviour. On videofluoroscopy, oral-preparatory and oral phase problems predominated, particularly with solids, silent aspiration occurred during the pharyngeal phase in 2/11, and delayed oesophageal transit occurred in 4/11. CONCLUSIONS: Feeding problems affecting behaviour, swallowing, food intake, and mother-child interaction occur in infants with GORD, who displayed a lack of development of age-appropriate feeding skills. The contribution of feeding problems to morbidity in GORD in infants has been underestimated in the past.

Bottle Feeding↗
PubMed1999

Effects of static orientation upon human optokinetic afternystagmus.

"Normal" human subjects were placed in a series of 5 static orientations with respect to gravity and were asked to view an optokinetic display moving at a constant angular velocity. The axis of rotation coincided with the subject's rostro-caudal axis and produced horizontal optokinetic nystagmus and afternystagmus. Wall (1) previously reported that these optokinetic afternystagmus responses were not well characterized by parametric fits to slow component velocity. The response for nose-up, however, was larger than for nose-down. This suggested that the horizontal eye movements measured during optokinetic stimulation might include an induced linear VOR component as presented in the body of this paper. To investigate this hypothesis, another analysis of these data has been made using cumulative slow component eye position. Some subjects' responses had reversals in afternystagmus direction. These reversals were "filled in" by a zero slow component velocity. This method of analysis gives a much more consistent result across subjects and shows that, on average, responses from the nose-down horizontal (prone) orientation are greatly reduced (p < 0.05) compared to other horizontal and vertical orientations. Average responses are compared to responses predicted by a model previously used to predict successfully the responses to post-rotatory nystagmus after earth horizontal axis rotation. Ten of 11 subjects had larger responses in their supine than their prone orientation. Application of horizontal axis optokinetic afternystagmus for clinical otolith function testing, and implications for altered gravity experiments are discussed.

Gravitation↗