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Biomedical subjects

D A Bailey

Publications and source records attributed to D A Bailey.

At least 37 records · Page 2Linked to original sources
PubMed1995

Comparison of areal and estimated volumetric bone mineral density values between older men and women.

We compared areal bone mineral density (BMD) of the total body (TBMD), antero-posterior lumbar spine at L3 (APS), lateral spine at L3 (LS) and femoral neck (FN). In order to understand better the effect of gender-related size differences on BMD, we also compared the estimated volumetric BMD at L3 (VLS) and the femoral neck (VFN). Subjects were asymptomatic women (n = 22) and men (n = 44) with an age range of 58-79 years. BMD at each site was measured by dual-energy X-ray absorptiometry using a Hologic 2000 in array mode. Results of the statistical analyses (ANOVA) showed the men to have significantly greater BMD at all areal sites [APS, LS (p < 0.05); FN (p < 0.01); TBMD (p < 0.001)]. The two estimated volumetric comparisons, however, showed no gender differences. Results demonstrate how measures from areal BMD measures can be misleading when comparing groups of different size. In older men and women planar measures may overestimate gender differences in BMD.

Aged↗
PubMed1995

Waivers for disqualifying medical conditions in U.S. Naval aviation personnel.

In the United States Navy, many diagnoses are considered disqualifying for aviation duty, but aircrew may be "waived" to return to flight duties after resolution of the disease or appropriate treatment of the condition. Personnel with waivers are usually subject to more frequent physical examinations and/or special diagnostic procedures. Although the Naval Aerospace and Operational Medical Institute promulgates written aeromedical guidelines as to which diseases may be waived and which may not, waivers are granted on a case-by-case basis considering not only the diagnosis, but the age, experience, and type of aviation duty of the individual in question. This study was undertaken to determine which conditions were most and least likely to be waived. We reviewed all records of aviators entered into the Naval Aviation Medical Data Retrieval System who had been diagnosed with a condition considered disqualifying for aviation duty, totaling over 39,000 records. Cases were stratified by diagnosis and aviation duty, and the percentage waived was calculated for major diagnostic groups. Among designated aviation personnel, approximately 68% of all aviators with a disqualifying diagnosis were recommended for a waiver. Otolaryngologic, musculoskeletal, and cardiovascular disorders accounted for nearly 50% of diagnoses in personnel recommended for a waiver. Fear of flying, personality disorders, and adjustment disorders were the three diagnoses least likely to be granted a waiver. The most frequently occurring disqualifying diagnoses were allergic rhinitis, obesity, disorders of refraction and accommodation, urolithiasis, and alcohol dependence.

Adolescent↗
PubMed1994

Familial comparison of bone mineral density at the proximal femur and lumbar spine.

Familial resemblance of bone mineral density (BMD) was studied in the lumbar spine and three regions of the proximal femur in 41 biological mother-daughter (M-D), 42 mother-son (M-S), 24 mother-grandmother (M-G) pairs and 18 mother-grandmother-daughter (M-G-D) triads. Children were placed into three maturity categories based on an assessment of secondary sex characteristics and growth velocities. Two sets of standardized BMD Z-scores were derived for the children based on either their chronological age or their maturational status. These scores were compared with maternal Z-scores derived from age-specific norms. Similar comparisons were made between the Z-scores of the mothers and grandmothers. For all three regions of the proximal femur and for the total AP lumbar spine the correlations between Z-score values were similar and significant (P < 0.05) between the M-G and M-D pairs ranging from 0.41 to 0.57. In general, the familial correlations improved when maturity-status based Z-scores were used for comparison. The absolute BMD values measured in the grandmothers and the three maturity groups of the children--expressed as a percentage of the BMD of the mothers--showed that at the neck and the trochanteric regions of the proximal femur the late-pubescent girls and boys had a significantly (P < 0.05) greater bone density than their mothers (115-123%), whereas at the AP spine these groups averaged only 88% of their mothers BMD. This site differential was not apparent when comparing the post-menopausal grandmothers with the pre-menopausal mothers (80% at both sites). Three generation comparisons demonstrated a strong familial resemblance in bone mineral density. The value of incorporating maturity-based versus chronological-based parameters for comparison with adult measures in studies that involve growing children at different stages of development was also demonstrated.

Adolescent↗
PubMed1994

Combat stress, combat fatigue, and psychiatric disability in aircrew.

A survey of the literature reveals little data regarding modern aviation and combat-related stress, fatigue, or psychiatric disabilities. What little is known about combat fatigue in aircrew is largely inferred from literature written about ground personnel. Understanding the unique aviation environment is necessary in order to develop effective combat fatigue prevention programs. This paper reviews and summarizes the literature regarding aeromedical aspects of combat stress reactions. Combat stress, fatigue, and psychiatric disabilities are common battlefield conditions, but are largely preventable. If not prevented or treated appropriately, combat stress reactions will frequently lead to more serious psychiatric disabilities, causing the evacuation of the combatant away from his or her unit with no expectation of return to duty. Appropriate intervention using the basic principles of proximity, immediacy, and expectancy are crucial in reducing these casualties and returning aviation personnel to combat duty.

Aerospace Medicine↗
PubMed1993

Regional and total body bone mineral content, bone mineral density, and total body tissue composition in children 8-16 years of age.

Normative values for total body bone mineral content (TBBM) and total body bone mineral density (TBMD) were derived from measurements on 234 children 8-16 years of age. In addition, bone mineral content (BMC) and bone mineral density (BMD) values for selected regions of interest and soft tissue (bone free lean and fat) for the total body are presented. Bone mineral and soft tissue values were determined by dual energy X-ray absorptiometry (DXA) using a Hologic QDR-2000 in the array mode. Results of a stepwise multiple regression analysis revealed a significant correlation between bone-free lean tissue (BFLT) and BMD (r2 = 0.80) in girls. Adding age to the equation accounted for an additional 2% of the variance (P < 0.05) and height accounted for another 1% of the variance (P < 0.05). Body weight and fat tissue (FT) did not account for any additional variance. In boys BFLT correlated significantly with BMD (r2 = 0.75; P < 0.05); none of the other predictor variables accounted for additional variance. No significant differences were found in TBBM or TBMD between boys and girls at any age. There was a significant overall gender effect for only three regions of interest. Boys had greater BMC in the head region and had greater BMD in the upper limbs, but post hoc analysis revealed no significant differences for any specific age groups. Girls had greater overall BMD in the pelvis, but this difference was only significant at the 15-16-year age group. The changes in BFLT and FT over the age ranges were consistent with the growth literature.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorptiometry, Photon↗
PubMed1993

Immunohistochemical sex steroid receptor distribution in endometrium from long-term subdermal levonorgestrel users and during the normal menstrual cycle.

The bleeding problems experienced by users of subdermal levonorgestrel implants (Norplant) remain unexplained. The aim of the present study was to investigate the oestrogen (ER) and progesterone receptor (PR) distribution in levonorgestrel-treated endometrial biopsies from 31 subjects recruited in Jakarta, Indonesia, and to compare the sex steroid receptor immunostaining with that of endometrium from 58 normally cycling women from Melbourne, Australia. Sex steroid receptor immunoreactivity was additionally compared with days of exposure to subdermal levonorgestrel, serum oestradiol and progesterone levels and days of bleeding during a 90-day reference period. An immunohistochemical technique with an alkaline phosphatase anti-alkaline phosphatase (APAAP) detection system for use in formalin-fixed paraffin wax embedded endometrial tissue was employed. Significantly greater mean immunostaining scores of stromal PR were observed in Norplant compared with control endometrium at all stages across the cycle. No significant correlations were demonstrated between sex steroid receptor immunostaining and days of exposure to subdermal levonorgestrel, serum oestradiol or progesterone concentrations or days of bleeding during a 90-day reference period. Whether the elevated stromal PR immunostaining in Norplant-treated endometrium is a consequence of increased synthesis or reduced turnover of receptor remains unclear. As yet it is undetermined whether increased PR immunoreactivity corresponds to an increase in number of functional PR.

Adult↗
PubMed1990

Effects of physical activity, dietary calcium intake and selected lifestyle factors on bone density in young women.

To assess the possible effects of physical activity, calcium intake and lifestyle factors on bone density, we measured the calcaneal bone density of 101 healthy female volunteers aged 20 to 35 years. Information was obtained through questionnaires and 1-week and 2-week recall tests. There appeared to be no relation between height, weight or age and bone density in the study sample. Childhood milk consumption, current dietary calcium intake, level of avocational physical activity and lifestyle variables such as cigarette smoking and coffee consumption, considered separately, did not reach statistically significant levels as determinants of bone density. Childhood physical activity level appeared to have a significant positive effect on bone density.

Absorptiometry, Photon↗
PubMed1990

Bone tissue and physical activity.

Bones provide more than just a structural framework for the body. In reality, bone is a multifunctional tissue dependent on, and sensitive to, a wide variety of biological, biochemical and biomechanical stimuli. This complex system is highly responsive to the mechanical stresses imposed by gravity and muscular contractions. Animal studies as well as human cross-sectional and longitudinal studies all point to the importance of weight-bearing physical activity and mechanical loading as the prime modalities in the preservation of skeletal integrity. Lack of weight-bearing activity is extremely harmful to the skeleton. Loss of skeletal density in individuals subjected to various types of immobilization or under conditions of weightlessness is well documented. The role of physical activity in the maintenance of skeletal integrity is a topic of considerable current interest when the increasing incidence of skeletal fragility in the elderly is taken into account.

Animals↗
PubMed1989

Epidemiology of fractures of the distal end of the radius in children as associated with growth.

We determined the annual incidence of fracture of the distal end of the radius for patients of all ages and both sexes in the province of Saskatchewan, using two data sets: data on hospital admissions for 1970 through 1984, and data on physician billing for 1978 through 1985. The rate of occurrence of this fracture in children, by age and sex, was compared with longitudinal data on the velocity of growth that was collected during the same time for children from the same population. We compared the incidences of the fracture with the results of studies on the levels of activity in children and adolescents during growth. We also compared the age-specific incidence of the fracture in children with the incidence in adults. For both data sets, the age at the peak incidence of fracture of the distal end of the radius almost perfectly matched the age at which peak velocity of growth in height occurs for boys and girls. For girls, the peak incidence occurred between the ages of 11.5 and 12.5 years and for boys, between 13.5 and 14.5 years; these ages corresponded to the mean peak velocity of growth at 11.9 years for girls and 14.3 years for boys. The age-adjusted incidence of the fracture in male subjects was highest at fourteen years and was not exceeded by that in female subjects until fifty-three to fifty-four years.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1988

Relationship of the body mass index with skinfolds, girths, and bone breadths in Canadian men and women aged 20-70 years.

The relationship of Quetelet index (w/h2), or body mass index (BMI), with the sum of skinfolds at five sites, two skinfold-corrected limb girths, and two bone breadths were studied in a cross-sectional sample of 12,282 men and 6,593 women aged 20-70 years. The correlations of the BMI with skinfolds (0.50), bone breadths (0.51), and girths (0.58) were too low for individual prediction. Contingency tables of the BMI and sum of skinfold categories further indict its use for the purpose of assessing adiposity status or monitoring change in individuals.

Adult↗
PubMed1987

Isolation and characterization of second chromosome mutagen-sensitive mutations in Drosophila melanogaster.

We have undertaken the study of a collection of 32 Drosophila melanogaster mus strains selected on the basis of developmental sensitivity to the DNA-damaging agents, methyl methanesulfonate (MMS), N-acetyl-2-aminofluorene (AAF), nitrogen mustard (HN2), and gamma-radiation. In total, 18 of these strains are sensitive to MMS. In turn, 14 of these exhibit unconditional MMS sensitivity (one of the latter mutants is lethal at 29 degrees C), whereas the other 4 are sensitive to MMS only at higher temperatures. Detailed analysis of the 7 strongest MMS-sensitive strains reveals that they identify 4 new second chromosome mus loci. Two mus loci are each represented by two alleles. One mutant (mus205B1) is allelic to a previously characterized mus locus. Different MMS-sensitive mutants display patterns of mutagen cross-sensitivity (to AAF, HN2, benzo[a]pyrene (BP), and gamma-rays) that parallel the range of responses seen in previously recovered X-linked and autosomal mus loci. In general, mutations that are strongly sensitive to MMS are also sensitive to one or both of the procarcinogens, AAF and BP, as opposed to HN2 and gamma-radiation. In contrast, the moderately MMS-sensitive mutations are sensitive to HN2 and gamma-rays, but not to AAF or BP. Of the 14 mus strains that are not sensitive to MMS, 5 are sensitive to AAF, another 5 are sensitive to HN2, and the remaining 4 are sensitive to gamma-rays.

Animals↗
PubMed1977

Aneurysms of the femoral artery.

Eight aneurysms of the femoral artery out of a total of 27 in 16 patients developed symptoms requiring surgery. The operation of choice was Dacron prosthetic replacement of the aneurysm with preservation of profunda femoris perfusion. The incidence of complications of aneurysms was 30 per cent. The asymptomatic aneurysms were untreated and did not cause the patients any inconvenience as observed at their follow-up. Hence, surgery is advocated only for patients who develop symptoms provided that adequate follow-up and community medicine facilities exist.

Adult↗
PubMed1976

Development of the Canadian Home Fitness Test.

The Canadian Home Fitness Test is a self-administered procedure in which the participant steps at an age- and sex-specific rhythm controlled by recorded music, then palpates the pulse immediately following activity. Validation of the test has shown a correlation of 0.72 with the results of a standard submaximum bicycle ergometer test, while the directly measured maximum oxygen intake is correlated even more closely (r = 0.88) with the attained stepping rate, body weight and recovery heart rate. Given modest training, subjects could measure their immediate postexercise heart rate (correlation with electro-cardiographic data, r = 0.94), although 10-second counts underestimated the true rate by an average of 7 beats/min. The safety of the test will be established ultimately by experience in its use in a large population; nevertheless, both theoretical considerations and results of trials in over 14 000 adults suggest the procedure can be self-administered without serious consequences. It is also well accepted by the general public and arouses considerable interest in most homes. The test can thus be recommended as providing an approximate measure of an individual's physical fitness in order to stimulate an increase in personal physical activity. It also has potential as a simple screening procedure that would allow paramedical personnel to record fitness levels and standardized exercise electrocardiograms in large segments of the population.

Adolescent↗
PubMed1974

A current view of Canadian cardiorespiratory fitness.

A standard Astrand bicycle ergometer test was used to predict the maximum oxygen intake of 672 female and 558 male volunteers ranging in age from 15 to 69 years. In terms of this index of cardiorespiratory performance Canadians were unfit relative to Swedish norms. Also, some 47% of women and 40% of men achieved only low or fair fitness categories when evaluated relative to American Heart Association recommendations. These results are poorer than those reported for Torontonians in 1966. Men perceive their cardiorespiratory fitness accurately but women do not. In both sexes adequate recreational activity apparently leads to maintenance of cardiorespiratory fitness.

Adolescent↗