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Biomedical subjects

J L Hopper

Publications and source records attributed to J L Hopper.

At least 163 records · Page 9Linked to original sources
PubMed1989

Reduced bone mass in daughters of women with osteoporosis.

To determine whether premenopausal daughters of women with postmenopausal osteoporosis have lower bone mass than other women of the same age, we measured the bone mineral content of the lumbar spine and femoral neck and midshaft, using dual-photon absorptiometry, in 25 postmenopausal women with osteoporotic compression fractures and in 32 of their premenopausal daughters; we then compared the results with those in normal controls. As compared with normal postmenopausal women, women with osteoporosis had lower bone mineral content in the lumbar spine, femoral neck, and femoral midshaft by 33, 24, and 15 percent, respectively (P less than 0.001 for each comparison by the one-tailed t-test). As compared with normal premenopausal women, the daughters of women with osteoporosis had lower bone mineral content at these sites by 7, 5, and 3 percent, respectively (P = 0.03, 0.07, and 0.15, respectively, by the one-tailed t-test). In terms of a standardized score, we calculated that the mean (+/- SEM) relative deficits in bone mineral content in the daughters of women with osteoporosis were 58 +/- 18 percent (lumbar spine) and 34 +/- 16 percent (femoral neck) of the relative deficits in their mothers. We conclude that daughters of women with osteoporosis have reduced bone mass in the lumbar spine and perhaps in the femoral neck; this reduction in bone mass may put them at increased risk for fractures. We also conclude that postmenopausal osteoporosis may result partly from a relatively low peak bone mass rather than from excessive loss of bone.

Bone and Bones↗
PubMed1989

Determinants of restenosis and lack of effect of dietary supplementation with eicosapentaenoic acid on the incidence of coronary artery restenosis after angioplasty.

The effect of an eicosapentaenoic acid-rich encapsulated preparation of fish oil on the incidence of early restenosis after coronary angioplasty was assessed by a randomized double-blind placebo-controlled study. A total of 108 patients received either 10 capsules of fish oil (1.8 g eicosapentaenoic acid, 1.2 g docosahexaenoic acid) or 10 control capsules (50% olive oil, 50% corn oil), commencing the day before angioplasty and continuing for 4 months after angioplasty, in addition to treatment with aspirin and verapamil. In 101 (94%) of the 108 patients, follow-up angiographic or postmortem result was evaluated at a mean (+/- SD) of 100 (+/- 22) days. Angiographic restenosis was observed in 34% of patients (29% of lesions) in the fish oil-treated group and 33% of patients (31% of lesions) in the control group (no significant difference). The overall incidence of angiographic restenosis was significantly higher in patients with 1) recurrent angina pectoris, 2) a positive exercise test at follow-up after angioplasty, 3) residual stenosis greater than 30% immediately after angioplasty, and 4) dilation of the left anterior descending or right coronary artery. Biochemical investigations showed a greater decrease in the serum triglyceride levels in the fish oil-treated group versus the control group (p less than 0.05) but no differences between the two groups in cholesterol levels or platelet counts over the 4 month period. In conclusion, in this study, the administration of fish oil at a dose of 10 capsules/day did not reduce the incidence of early restenosis after coronary angioplasty.

Adult↗
PubMed1989

Modelling sibship environment in the regressive logistic model for familial disease.

Recently analytical models for pedigree disease data have been developed that combine genetic and epidemiological modelling techniques. The regressive logistic model [Bonney, Biometrics 42: 611-625; 1986] relies on decomposing the likelihood of a pedigree into the product of conditional probabilities, one for each individual, by imposing a (natural) order on pedigree members. In addition to modelling measured epidemiological variables, vertical transmission, transmission of unmeasured ousiotypes (a special case being genotypes), and some modelling of sibship dependencies have been proposed. In this paper the model is extended to include an unmeasured sibship environment factor using a log-linear model for binary pedigree traits [Hopper et al., Genet Epidemiol 1: 183-188; 1984], which breaks the pedigree into conditionally independent groups. Statistical issues, such as designs for which these factors will be discernible and tests of fit, are discussed.

Environment↗
PubMed1989

Difference in effect of cultured fetal pancreas transplants on retinal and renal capillary basement membrane thickness in diabetic mice.

The goal of endocrine pancreas transplants should be the prevention of diabetic complications. The differential effect of grafts of organ-cultured fetal mouse pancreas on diabetic complications in the retina and kidney was tested by comparing capillary basement membrane thickness (BMT) in mice made diabetic with streptozotocin and transplanted either early or late, or treated with insulin. BALB/c female mice were grafted with a single organ-cultured syngeneic fetal pancreas at either 3 weeks or 7 months after induction of diabetes. Controls were sex- and age-matched nondiabetic; diabetic untreated; and diabetic insulin-treated mice. All mice were killed at 20 months of age and their eyes and kidneys fixed for electron microscopy. BMT was measured on coded micrographs. In all mice glomerular capillary BM were thicker than retinal capillary BM. Mice grafted early after the induction of diabetes had normal BMT in both sites, while those transplanted after 6 months of disease had normal retinal, but thickened glomerular, capillary BM. In each case the late-transplanted animals had BM thickness significantly less than the insulin-treated or untreated diabetics.

Animals↗
PubMed1989

The biology of panic-genetic evidence.

Family aggregations for panic disorder as defined by the American Psychiatric Association's DSM-III classification were examined at the Austin Hospital in Victoria, Australia, covering 636 individuals. The results were consistent with the common genetic relatedness of parents to offspring and of sibling pairs, but also consistent with other factors common to the family. The family data alone were not sufficient to draw conclusions about the cause of aggregation.

Adolescent↗
PubMed1988

Review of FISHER.

Explore the source record for details and available documents.

Genetic Techniques↗
PubMed1988

A random walk model for evaluating clinical trials involving serial observations.

For clinical trials where the variable of interest is ordered and categorical (for example, disease severity, symptom scale), and where measurements are taken at intervals, it might be possible to achieve a greater discrimination between the efficacy of treatments by modelling each patient's progress as a stochastic process. The random walk is a simple, easily interpreted model that can be fitted by maximum likelihood using a maximization routine with inference based on standard likelihood theory. In general the model can allow for randomly censored data, incorporates measured prognostic factors, and inference is conditional on the (possibly non-random) allocation of patients. Tests of fit and of model assumptions are proposed, and application to two therapeutic trials of gastroenterological disorders are presented. The model gave measures of the rate of, and variability in, improvement for patients under different treatments. A small simulation study suggested that the model is more powerful than considering the difference between initial and final scores, even when applied to data generated by a mechanism other than the random walk model assumed in the analysis. It thus provides a useful additional statistical method for evaluating clinical trials.

Algorithms↗
PubMed1988

Immunoglobulin allotypes Gm and Km in hematologic malignancies.

Immunoglobulin allotypes of the Gm and Km systems have been compared in patients with various forms of hematologic malignancies and healthy controls of the same ethnographic background. These comparisons found an increased frequency of the haplotype Gm and a decreased frequency of Gm in patients with Hodgkin's disease; a decreased frequency of Gm in diffuse, large-cell lymphoma patients; a decreased frequency of Gm and an increased frequency of Gm in acute myeloid leukemia patients; a decreased frequency of Gm in chronic myeloid leukemia patients, and an increased frequency of the phenotype Km(1+) in chronic lymphocytic leukemia patients. These results support previous suggestions of the involvement of immunoglobulin allotypes in the susceptibility to some forms of human hematologic malignancy.

Gene Frequency↗
PubMed1988

Effect of early menopause on bone mass in normal women and patients with osteoporosis.

PURPOSE: Early menopause is widely regarded as a risk factor for osteoporosis. The aim of this study was to determine whether this risk is conferred by a lower bone mass. PATIENTS AND METHODS: Two hundred thirteen normal postmenopausal women and 55 women with postmenopausal osteoporosis (vertebral fractures) underwent bone mass measurements at the lumbar spine, femoral neck, and midshaft using dual-photon absorptiometry. To examine the effect of early menopause, postmenopausal normal women were stratified according to whether menopause occurred before or after the age of 50 years. Patients with osteoporosis were stratified in the same way. RESULTS: Patients with osteoporosis had menopause at an earlier age than control subjects, but the difference in bone mass between the patients with osteoporosis and the control subjects could not be attributed to this earlier age at menopause. Furthermore, within the osteoporotic patient group, those with early menopause did not have lower bone mass than those with normal age at menopause. Similarly, within the normal subject group, those with early menopause did not have lower bone mass than those with normal age at menopause. CONCLUSION: Patients with osteoporosis have lower bone mass, which is independent of the age at menopause. Although a small effect (less than or equal to 5 percent) of early menopause on bone mass cannot be entirely excluded, these data suggest that the amount of bone lost following menopause is the same irrespective of the age at which menopause occurs. If early menopause is a risk factor for osteoporosis, the risk is not conferred by a bone mass substantially lower than predicted had menopause occurred later, but may be related to the duration of exposure to minimal trauma at low bone mass.

Age Factors↗
PubMed1988

An autoradiographic study of the developing parietal cell population in neonatal pigs.

Autoradiographic labelling using tritiated thymidine ([3H]TdR) was used to examine the pattern of development of gastric parietal cells in newborn pigs. Specific objectives were to establish sites in the gland where cells with a characteristic parietal cell morphology first appear, the extent of their migration or displacement, and the kinetics of any development and migration that occurs. Five newly-born littermate piglets were given a virtually continuous label of [3H]TdR over 24 hr, sacrificed at 1, 3, 5, 7 and 10 days thereafter, and samples of the gastric mucosa taken. The percentage of labelled parietal cells as a function of position in the oxyntic gland was measured for each pig. A generalized log linear model was fitted to the data using the statistical package GLIM, confirming a significant trend for labelled cells to occupy higher sites in the oxyntic gland as the time since labelling of cells increased. Goodness of fit tests showed that the trend effect was highly unlikely to be due to the variability of cell distribution from animal to animal. The dynamics of the parietal cell population and the strengths of GLIM for analysing cell labelling data are discussed.

Age Factors↗
PubMed1988

Impaired glucose tolerance, hyperinsulinemia, and hypertriglyceridemia in Australian aborigines from the desert.

A cross section of adult full-blooded Aborigines from three small isolated communities in the desert region of northwest Australia was surveyed for diabetes, impaired glucose tolerance (IGT), insulin levels, and lipoprotein lipids. Sixty-three men and 86 women from a total adult population of 330 were tested. Of the people tested, 67.6% had normal glucose tolerance, 25% had IGT, and 7.4% had diabetes. Both diabetes and IGT were strongly age related. Fasting insulin levels and insulin responses to oral glucose (elevation above basal) were elevated. Although fasting insulin rose with age, insulin response did not rise after adjustment for body mass index (BMI). Plasma triglyceride levels were high, particularly in men greater than 35 yr old (3.13 +/- 0.32 mM), but cholesterol levels were not elevated. Multiple regression analysis of fasting glucose, 2-h glucose, plasma triglyceride, fasting insulin, and insulin response for the nondiabetic subjects revealed 1) BMI was an independent risk factor for elevated 2-h glucose levels in women but not in men and was strongly related to fasting insulin concentrations in both genders; 2) fasting insulin concentration was an independent risk factor for increases in fasting glucose, insulin response, and triglyceride levels; 3) insulin response was related to the 2-h glucose level; 4) fasting and 2-h glucose levels and fasting insulin and triglyceride concentrations all rose with age in both genders, with the rate of increase generally greater in men. The most striking difference between these desert Aborigines and previously studied coastal Aborigines from the same geographical region was the significantly higher insulin response.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1987

A family study of panic disorder.

Panic disorder, as defined by the DSM III diagnostic criteria, was diagnosed in 117 probands for whom age of onset ranged from 10 to 59 years, with a mean of 26.6 years. Diagnosis of parents and siblings was based on interviews with the probands, and only those with "definite" panic disorder by the FISC criteria were considered to be affected. The pattern of concordances for panic across different groups of relatives was estimated concurrently by a log-linear model for binary pedigree data, assuming different values for the cumulative risk. When an adjustment for age was made, based on the age of onset of probands, there was no significant difference between parent-offspring concordance and sibling concordance. There was a negative, but not significant, concordance between spouse pairs. Assuming the lifetime cumulative risk was 1.9% for males and 4.7% for females, values considered appropriate for this population, our model predicted that the presence of an affected parent or sibling incurs an approximately five times increase in the risk of developing panic disorder. Our model assumes in effect that this risk is multiplied for each further affected relative. Although the common concordance across relationship groups is consistent with a genetic hypothesis, it can also be explained by common family environmental factors. There is a need for further pedigree studies, using twins and relatives, for example, and reliable information on the cumulative risk.

Adolescent↗
PubMed1987

The relationship of acute insulin sensitivity to the progression of vascular disease in long-term type 1 (insulin-dependent) diabetes mellitus.

In 51 individuals with Type 1 (insulin-dependent) diabetes mellitus initially of more than 15 years' duration, the acute hypoglycaemic effect of intravenous insulin (0.11 IU/kg) was related to outcome over 18 years. This acute insulin sensitivity, or glucose assimilation index, was reproducible over the period of study. At 18-year follow-up, initial low glucose assimilation index (less than 0.082 mmol X l-1 X min-1 was significantly (p less than 0.01) associated with death from vascular disease. Low glucose assimilation index was similarly significantly (p less than 0.01) associated with progression of atherosclerotic disease, but not with microangiopathy alone. Hypertension (systolic blood pressure greater than 150 mmHg and/or diastolic blood pressure greater than 95 mmHg) was the only other parameter significantly (p less than 0.01) related to outcome, but this relationship was no longer significant once glucose assimilation index had been taken into account. A linear logistic analysis confirmed that acute insulin sensitivity was independently associated with outcome. Neither initial clinical control of diabetes nor glycosylated haemoglobin level in the 26 survivors was related to vascular prognosis.

Blood Glucose↗
PubMed1987

Dynamic CT brain scanning in the haemodynamic evaluation of cerebral arterial occlusive disease.

Dynamic cerebral CT scanning (DCT) was used to quantitatively analyse the haemodynamic effects of extracranial and intracranial arterial occlusive lesions in 17 patients with TIA's or minor cerebral infarcts. Using DCT and gamma variate curve fitting, mean transit times were determined for the terminal internal carotid arteries, middle cerebral arteries and middle cerebral-supplied Sylvian cortex at the level of the Circle of Willis. Six patients were studied sequentially, four before and after transcranial bypass surgery. No arterial or tissue delays were found in patients without haemodynamic arterial lesions or cortical infarcts. Seven of nine patients with haemodynamic, extracranial carotid lesions showed ipsilateral delays in arterial or tissue transit times. Tissue delays usually correlated with CT or clinical evidence of infarction. Improved haemodynamics in patients re-studied correlated with the effects of surgery or clinical recovery. DCT has several important limitations but has the potential to provide additional haemodynamic information about the cerebral circulation in selected patients with cerebral arterial occlusive disease.

Adult↗
PubMed1987

Innovations in the statistical analysis of twin studies.

Advances in computer technology have made possible a greater sophistication in the statistical analysis of pedigree data, however this is not necessarily manifest by fitting more comprehensive causative models. Planned twin and family studies measure numerous explanatory variables, including perhaps genetic and DNA marker information status on all pedigree members, and the cohabitation of all pairs of individuals. A statistical analysis should examine the contribution of these measured factors on individual means, and in explaining the variation and covariation between individuals, concurrently with the postulated effect of unmeasured factors such as polygenes. We present two models that meet this requirement: the Multivariate Normal Model for Pedigree Analysis for quantitative traits, and a Log-Linear Model for Binary Pedigree Data. For both models, important issues are examination of fit, detection of outlier pedigrees and outlier individuals, and critical examination of the model assumptions. Procedures for fulfilling these needs and examples of modelling are discussed.

Humans↗
PubMed1987

Analysis of dynamic computed tomography scan brain images.

Dynamic computed tomography (DCT) of the brain can be used to study the transit time of first passage of a bolus injection of intravenous contrast medium. Comparison of cerebral perfusion with corresponding sites in the left and right cerebral hemispheres is of diagnostic interest because a real difference may be indicative of differential damage. A method for estimating the mean transit time and approximating its standard error, by assuming a gamma function for the response curve and an appropriate error structure, is presented. Expressed as log-linear regression, estimation is achieved by maximum likelihood using a statistical package such as GLIM or SPSSX. Statistical comparison of the mean transit time to or between corresponding sites can be made; issues of model fit and biologic interpretation need to be considered as an integral part of statistical inference. These methods enable users of CT equipment (without specific software for estimation of mean transit time) to use any log-linear routine for diagnostic purposes. An example of the fit procedure and interpretation in the light of clinical evidence is given.

Brain↗
PubMed1987

Genetic determinants of bone mass in adults. A twin study.

The relative importance of genetic factors in determining bone mass in different parts of the skeleton is poorly understood. Lumbar spine and proximal femur bone mineral density and forearm bone mineral content were measured by photon absorptiometry in 38 monozygotic and 27 dizygotic twin pairs. Bone mineral density was significantly more highly correlated in monozygotic than in dizygotic twins for the spine and proximal femur and in the forearm of premenopausal twin pairs, which is consistent with significant genetic contributions to bone mass at all these sites. The lesser genetic contribution to proximal femur and distal forearm bone mass compared with the spine suggests that environmental factors are of greater importance in the aetiology of osteopenia of the hip and wrist. This is the first demonstration of a genetic contribution to bone mass of the spine and proximal femur in adults and confirms similar findings of the forearm. Furthermore, bivariate analysis suggested that a single gene or set of genes determines bone mass at all sites.

Adult↗