Biomedical subjects

J L Hopper

Publications and source records attributed to J L Hopper.

At least 91 records · Page 5Linked to original sources

PubMed1998

Using longitudinal data to define the perimenopause by menstrual cycle characteristics.

OBJECTIVES: To determine which aspects of menstrual change best predict time to postmenopause. METHODS: A total of 250 Australian-born women aged 45-55 years were divided into five menstrual status categories: Group I reported no change in menstrual flow or frequency; Group II reported change in flow; Group III reported change in frequency; Group IV reported change in both frequency and flow; and Group V reported between 3 and 11 months of amenorrhea. Menstrual status groups were compared on baseline data for age, hormone levels, hot flushes and self-rated menopausal status. The proportion of women moving to postmenopause in subsequent years was compared using 4 years of follow-up data. RESULTS: Women in Group V were older, had lower estradiol and inhibin levels, higher follicle stimulating hormone levels, and were more likely to report hot flushes, and to self-rate themselves as having started the menopausal transition, compared with the women who had menstruated in the last 3 months (Groups I-IV). Groups I and II were similar in age and hormonal status, as were Groups III and IV. The proportion of women who had moved to postmenopausal status in the 4 years after baseline were 12%, 14%, 58%, 53% and 94% for Groups I-V, respectively. CONCLUSIONS: Amenorrhea is the best predictor of future menopause followed by changes in menstrual frequency. Change in flow only was not predictive of future menopause. A two-stage classification scheme is suggested for defining the perimenopause. 'Early perimenopause' is defined as the self-reporting of changes in menstrual frequency over the last year, and 'late perimenopause' is defined as the self-report of 3-11 months of amenorrhea.

Amenorrhea↗

PubMed1997

Regressive logistic modeling of familial aggregation for asthma in 7,394 population-based nuclear families.

The aim of this population-based study was to determine whether asthma aggregates in families, and if so, whether aggregation was consistent with environmental and/or genetic etiologies. Data were from 7,394 nuclear families (41,506 individuals) from the 1968 Tasmanian Asthma Survey, in which all Tasmanian schoolchildren born in 1961 were surveyed by respiratory questionnaire completed by their parents. Similar data were obtained for parents and siblings of probands. For a child, having ever had asthma was predicted by a parent or sibling having ever had asthma; odds ratio (OR) = 3.13 (95% confidence interval [CI] 2.82-3.48) for mother, 2.99 (2.69-3.32) for father, and 3.47 (3.23-3.72) for a sibling. Regressive logistic modeling showed that, in addition to parent-offspring effects, the data were consistent with the existence of an unmeasured factor shared by siblings, evident in 15% (SE 2%) of families and associated with a conditional OR of 9.68 (8.27-11.32). Familial aggregation was best described by a general oligogenic model with non-Mendelian transmission probabilities. Of the Mendelian models, a codominant model with an allele frequency of 16% (SE 0.3%) was preferred. Under a dominant model there was evidence for additional parent-offspring and sibling effects of similar magnitude. It is unlikely that there is one major loci influencing asthma susceptibility; the overall effects of asthma genes in the population are more likely to be inherited codominantly, at least for the majority of loci of major etiological importance. The role of environmental factors in explaining part of familial aggregation for asthma cannot be ruled out, as major triggers of asthma attacks are familial.

Asthma↗

PubMed1997

A co-twin study of the effect of calcium supplementation on bone density during adolescence.

The effect of calcium supplementation on bone mineral density (BMD) was evaluated in female twin pairs aged 10-17 years with a mean age of 14 years. Forty-two twin pairs (22 monozygotic, 20 dizygotic; (including one monozygotic pair from a set of triplets) completed at least 6 months of the intervention: 37 pairs to 12 months and 28 pairs to 18 months. BMD was measured by dual-energy X-ray absorptiometry (DXA). In a double-blind manner, one twin in each pair was randomly assigned to receive daily a 1000 mg effervescent calcium tablet (Sandocal 1000), and the other a placebo tablet similar in taste and appearance to the calcium supplement but containing no calcium. Compliance (at least 80% tablets consumed), as measured by tablet count, was 85% in the placebo group and 83% in the calcium group over the 18 months of the study, on average increasing dietary calcium to over 1600 mg/day. There was no within-pair difference in the change in height or weight. When the effect of calcium supplementation on BMD was compared with placebo at approximately 6, 12 and 18 months, it was found that there was a 0.015 +/- 0.007 g/ cm2 greater increase in BMD (1.62 +/- 0.84%) at the spine in those on calcium after 18 months. At the end of the first 6 months there was a significant within-pair difference of 1.53 +/- 0.56% at the spine and 1.27 +/- 0.50% at the hip. However, there were no significant differences in the changes in BMD after the initial effect over the first 6 months. Therefore, we found an increase in BMD at the spine with calcium supplementation in females with a mean age of 14 years. The greatest effect was seen in the first 6 months; thereafter the difference was maintained, but there was no accelerated increase in BMD associated with calcium supplementation. The continuance of the intervention until the attainment of peak bone mass and follow-up after cessation of calcium supplementation will be important in clarifying the optimal timing for increased dietary calcium and the sustained, long-term effects of this intervention.

Adolescent↗

PubMed1997

Nandrolone decanoate and intranasal calcitonin as therapy in established osteoporosis.

This study used a randomized, 2 x 2 factorial design to evaluate over 2 years the effect of intranasal salmon calcitonin and intramuscular nandrolone decanoate on bone mass in elderly women with established osteoporosis. The study was double masked in relation to calcitonin and open in relation to nandrolone decanoate. One hundred and twenty-three women aged 60-88 years who had sustained a previous osteoporotic fracture, or had osteopenia, were recruited through an outpatient clinic. Women were assigned to one of four groups: (1) daily placebo nasal spray, (2) 400 IU intranasal calcitonin daily, (3) 20 intramuscular injections of 50 mg nandrolone decanoate (given as two courses of 10 injections) plus placebo nasal spray, or (4) 20 injections of 50 mg nandrolone decanoate plus 400 IU intranasal calcitonin daily. All subjects received 1000 mg calcium supplementation daily. Outcomes measured included changes in bone mineral density (BMD) at the lumbar spine, as measured by dual-energy quantitative computed tomography (DEQCT), in BMD of the proximal femur, and BMD and bone mineral content (BMC) of the lumbar spine and forearm, as measured by dual-energy X-ray absorptiometry (DXA). Significant positive changes from baseline in DXA BMC at the lumbar spine were observed over 2 years in the calcitonin group (5.0 +/- 1.9%, mean +/- SE) and in the nandrolone deconate group (4.7 +/- 1.9%) but not in the placebo group (1.1 +/- 2.2%) or the combined therapy group (0.7 +/- 1.8%). Modelling based on the 2 x 2 factorial design revealed that nandrolone decanoate was associated with a 3.8 +/- 1.8% (p < 0.05) gain in DXA BMD at the proximal femur. Modelling also revealed that calcitonin treatment was associated with a loss of 11.5 +/- 4.7% in DEQCT BMD at the lumbar spine and a loss of 3.7 +/- 1.8% in DXA BMD at the proximal femur (p < 0.05). There was in vivo antagonism between the two medications of 7.9 +/- 3.9% for DXA BMC at the lumbar spine. Both agents caused positive changes from baseline in lumbar spine BMC. Nandrolone decanoate had beneficial effects on BMD at the proximal femur. This dose of intranasal calcitonin was associated with deleterious effects on trabecular BMD at the lumbar spine and total BMD at the proximal femur. There may be significant clinical antagonism between these two medications.

Administration, Intranasal↗

PubMed1997

Genetic and environmental components of the population variance in bone density.

Understanding of the genetic and environmental factors contributing to the differences in fracture rates between young and old, between women and men, and between races is limited. The reasons for this may partly relate to the lack of a detailed understanding of the structural basis of bone fragility. This information, although difficult to obtain because of the invasiveness of bone biopsy, will be required if advances are to occur. aBMD cannot be relied upon as an endpoint in the study of the pathophysiology of osteoporosis. Advances will require the description of the age-, gender and race-specific means and variances in trabecular number, thickness, spacing and orientation, cortical thickness, and bone size and shape in women and men of different racial groups. Subsequent comparison of the structures in young versus old, female versus male, and in racial groups may reveal the structural differences from which inferences may be made concerning the differences in fracture rates between these groups. By defining the structural basis for bone fragility, the genetic and modifiable environmental determinants of these structures may then be identified, providing hypotheses to be tested in randomized trials aimed at reducing the incidence of fractures in these groups.

Adolescent↗

PubMed1997

Sexuality, hormones and the menopausal transition.

OBJECTIVES: To assess the validity and reliability of a sexuality questionnaire, and to assess the relationship of sexual functioning to age, menopausal status and hormone levels. METHODS: Cross-sectional analysis of a population-based cohort of 201 women aged 48-58 years in the fourth year of a longitudinal study. Sexual functioning was measured by self-completed questionnaire. E2, FSH. Inhibin, total T and SHBG were sampled on cycle days 4-8 or after 3 months of amenorrhoea. RESULTS: Internal consistency, as measured by Cronbach's alpha, was 0.71. Six factors were found on principal components factor analysis: (1) Feelings for Partner, (2) Sexual Responsivity, (3) Sexual Frequency, (4) Libido, (5) Partner Problems and (6) Vaginal Dryness/Dyspareunia. Sexual Responsivity decreased with age (beta = -0.060, P = 0.05), and Vaginal Dryness/Dyspareunia decreased with log E2 (beta = -0.181. P < 0.001). Testosterone was not associated with the aspects of female sexual functioning measured in this study. CONCLUSIONS: This longitudinal study found that most aspects of female sexual functioning were not affected by age, menopausal functioning or hormone levels.

Age Factors↗

PubMed1997

Genetic factors associated with altered sodium transport in human hypertension: a twin study.

1. Na+/H+ antiporter/exchange activity (NHE) in human cheek epithelial cells was assessed in 288 female twins and siblings. The genetic contribution of factors to NHE activity was assessed in 128 matched twin pairs (76 monozygotic (MZ); 52 dizygotic (DZ)). 2. There was a small reduction in NHE with age and body mass index. The significant correlations (+/-their standard error (SE)) within MZ and DZ pairs of twins were 0.54 +/- 0.08 and 0.26 +/- 0.13, respectively, implying that genetic factors accounted for 54% of the variance in age-adjusted NHE. There was no cross-sectional relationship between NHE and measures of blood pressure. Based on within-pair differences, however, there was a weak negative association (r = 0.22; P < 0.05) between mean arterial pressure and NHE. 3. It remains to be determined whether NHE in cheek cells is associated with blood pressure tracking over time in young females.

Adolescent↗

PubMed1997

Changes in physical activity and health outcomes in a population-based cohort of mid-life Australian-born women.

Cross-sectional studies and intervention programs have suggested that physical activity is a potential contributor to the health and wellbeing of mid-life and older women. This prospective longitudinal study investigates whether natural changes in physical activity are associated with changes in health outcomes in a population-based cohort of Australian-born women aged 45-55 years living in Melbourne. Of the 352 women from the Melbourne Women's Midlife Health Project who filled in a base-line physical activity questionnaire, 292 (83 per cent) were evaluated around three years later with regard to physical activity, psychological wellbeing, self-rated health, symptoms experienced, body mass index (BMI), blood pressure and serum lipids. Mean (SD) physical activity measured at base-line was 5.9 (5.7) hours/week, or 1496 (1449) kcal/week; mean (SD) change in physical activity per week was 0.05 (5.24) hours, or 44 (1347) kcal, indicating that although mean change was small there was substantial variation in change. There were significant increases in BMI (P < 0.001), wellbeing (P < 0.05), the number of reported menopause-related symptoms, and high-density lipoprotein cholesterol (HDL-C) levels (P < 0.001), and a decrease in low-density lipoprotein cholesterol (LDL-C) levels (P < 0.05). Change in level of physical activity was positively associated with change in HDL-C (P < 0.01) and change in wellbeing (P = 0.08) and negatively associated with change in coronary heart disease risk score. By increasing physical activity in mid-life, women may reduce at least one risk factor (HDL-C) associated with coronary heart disease.

Australia↗

PubMed1997

Volumetric analysis of cerebral hypoperfusion on SPECT: validation and reliability.

UNLABELLED: A method of volumetric analysis of hypoperfusion on 99mTc-labeled hexamethylpropylene amine oxime SPECT has been developed. This analysis integrates both the size and severity of perfusion reduction, yielding an equivalent volume of cortical tissue having zero blood flow, or the effective hypoperfusion volume. This study aimed to validate the methodology in vitro using the Hoffman brain phantom and two different camera systems, to examine the relationship between spatial resolution and accuracy of volume measurement and to assess the interobserver variability in SPECT studies of stroke patients. METHODS: Simulated cortical lesions of three different sizes were sequentially incorporated into the Hoffman brain phantom and imaged using both single- and triple-head camera systems. For each system and for each lesion size, successive acquisitions were performed using three progressively larger radii of camera rotation. The hypoperfusion volume for each study was measured three times by a blinded observer, and the percentage difference from the true lesion volume was then calculated. SPECT studies of 32 stroke patients were independently analyzed by two blinded observers. RESULTS: At the smallest radii of rotation, mean (s.d.) percentage difference between observed and true volumes was 0.90% (4.80%) for the triple-head and 4.50% (11.58%) for the single-head system. The degree of overestimation was similar for both systems. Percentage overestimation was strongly associated with radius of rotation (B = 0.71 +/- 0.32, p = 0.04 for the triple-head system; B = 1.26 +/- 0.55, p = 0.03 for the single-head system) but not with lesion size. The mean difference between hypoperfusion volumes of stroke patients obtained by two observers was 0.045 (3.240) cm3, which was not significant. CONCLUSION: This study has shown that this technique of volumetric analysis of regional hypoperfusion on SPECT is both highly accurate and reproducible between two different camera systems. The degree of overestimation chiefly relates to diminishing spatial resolution. Despite some element of subjectivity, the interobserver variability is negligible.

Animals↗

PubMed1996

Familial temporal lobe epilepsy: a common disorder identified in twins.

We describe a new syndrome of familial temporal lobe epilepsy in 38 individuals from 13 unrelated white families. The disorder was first identified in 5 concordant monozygotic twin pairs as part of a large-scale twin study of epilepsy. When idiopathic partial epilepsy syndromes were excluded, the 5 pairs accounted for 23% of monozygotic pairs with partial epilepsies, and 38% of monozygotic pairs with partial epilepsy and no known etiology. Seizure onset for twin and nontwin subjects usually occurred during adolescence or early adult life. Seizure types were simple partial seizures with psychic or autonomic symptoms, infrequent complex partial seizures, and rare secondarily generalized seizures. Electroencephalograms revealed sparse focal temporal interictal epileptiform discharges in 22% of subjects. Magnetic resonance images appeared normal. Nine affected family members (24%) had not been diagnosed prior to the study. Pedigree analysis suggested autosomal dominant inheritance with age-dependent penetrance. The estimated segregation ratio was 0.3, indicating an overall penetrance of 60% assuming autosomal dominant inheritance. The mild and often subtle nature of the symptoms in some family members may account for lack of prior recognition of this common familial partial epilepsy. This disorder has similarities to the El mouse, a genetic model of temporal lobe epilepsy with a major gene on mouse chromosome 9, which is homologous with a region on human chromosome 3.

Adolescent↗

PubMed1996

Retired elite female ballet dancers and nonathletic controls have similar bone mineral density at weightbearing sites.

Elite female ballet dancers exhibit several risk factors for osteoporosis during their performing years. To study the long-term effect of this lifestyle, we compared the bone mineral density (BMD) of 101 retired elite female ballet dancers (mean age 51 years, SD = 14 years) and 101 normal controls, derived from a twin study, matched hierarchically for age, height, weight, and menopausal status. The dancers, who had been retired for a mean of 25.6 years (range 1-53 years) reported a greater prevalence of previous menstrual disturbance, greater lifetime alcohol intake and smoking, and a lower dietary milk intake in adolescence than controls (all p < 0.05). However, current exercise in the dancers was twice that of the controls (p < 0.01). The BMD of retired dancers did not differ from that of the controls at weightbearing sites. The mean +/- SE difference in BMD (dancers minus controls) was 0.009 +/- 0.013 at the total body, -0.009 +/- 0.018 at the total hip, 0.005 +/- 0.017 at the femoral neck, 0.014 +/- 0.018 at the femoral trochanter, 0.036 +/- 0.022 at the femoral intertrochanter and -0.017 +/- 0.021 at the lumbar spine. Retired dancers had lower mean (+/- SE) BMD at the nonweightbearing sites: ultradistal radius (-0.029 +/- 0.008) (p < 0.01) and at the midthird radius (-0.019 +/- 0.011) (p < 0.05). There was no difference in the proportion in each of the World Health Organization (WHO) categories of osteopenia (t score -1.0 to -2.5) and osteoporosis (t score < -2.5) at any of the measured sites. Regression analysis revealed that menstrual disturbance was negatively associated with BMD at the lumbar spine and the ultradistal radial sites, but not at the weightbearing femoral sites. This sample of retired elite ballet dancers who had multiple historical risk factors does not appear to have an increased risk for future hip or vertebral fracture based on WHO standards.

Absorptiometry, Photon↗

PubMed1996

Hot flushes, menstrual status, and hormone levels in a population-based sample of midlife women.

OBJECTIVE: To determine the frequency of hot flushes in a population sample of 453 pre-, peri-, and postmenopausal women (aged 48-59 years), and to investigate the relationship of hot-flush reporting with menstrual status, serum levels of estradiol (E2), inhibin, and FSH, history of premenstrual complaints, and physical and life-style factors. METHODS: We used a population-based sample. Interviews were conducted in the women's homes. RESULTS: Frequency of hot-flush reporting was associated with menstrual status (P < .001). Twenty-nine percent of women who had more than 3 and less than 12 months of amenorrhea, and 37% of postmenopausal women experienced hot flushes several times a day. In total, 13% of premenopausal women, 37% of perimenopausal women, 62% of postmenopausal women, and 15% of women on hormone therapy reported having had at least one hot flush in the previous 2 weeks. Follicle-stimulating hormone levels were higher in women who experienced hot flushes at least once a day or more (P < .001); E2 levels were higher in women experiencing one or no hot flushes per week (P < .001). The women in the perimenopausal group who experienced hot flushes had higher FSH levels (P = .008) and were more likely to have reported premenstrual complaints at the first interview 3 years earlier (P = .03). In the postmenopausal group, there was no significant difference with any of the variables studied between the women who were experiencing hot flushes and those who were not. CONCLUSION: Reporting of hot flushes is greatest 3 months or more after the final menstrual period. The frequency of hot flushes is associated with increasing FSH, decreasing E2, and a history of premenstrual complaints.

Body Mass Index↗

PubMed1996

Determinants of hip axis length in women aged 10-89 years: a twin study.

Hip axis length (HAL), a measure of femoral geometry, has been shown to predict hip fracture in white women over the age of 67 years, independently of bone mineral density at the femoral neck. A cross-sectional study of 304 pairs of female twins [176 monozygous (MZ) and 128 dizygous (DZ)], aged between 10 and 89 years, was performed to examine the influence of age, constitutional, lifestyle, and genetic factors on HAL. HAL was calculated from dual energy X-ray absorptiometry scans of the proximal femur using an automated technique with an Hologic QDR-1000W. Lean mass, fat mass, height, and weight were also measured. Maximum mean HAL was achieved by the age of 15 years. After this age there was no discernible dependency of mean HAL on age. Using within-pair differences, after adjusting for height there were no other independent constitutional or lifestyle predictors. Cross-sectionally, after adjustment for height, MZ and DZ correlations were 0.79 (95% CI: 0.73-0.84) and 0.54 (95% CI: 0.39-0.68), respectively, and independent of age. The MZ correlation exceeded the DZ correlation (p < 0.001). The best-fitting model apportioned 79% (SE 7%) of variation in height-adjusted HAL to additive genetic factors. There was marginal evidence that an environmental influence shared by twins explained 31% (SE 16%) of height-adjusted variance (p = 0.07), in which case the genetic variance was reduced to 51% (SE 15%). Adjustment for height had reduced the magnitude of total variance by 26%, and 95% of this reduction was in the additive genetic component. Applying a previously described theoretical model, approximately 10% of the increased risk of hip fracture associated with a maternal history of hip fracture could be attributed to the genetic factors determining HAL. We conclude that, in women, adult HAL is achieved by midadolescence. After adjustment for height, which is itself largely under genetic influence, other genetic factors appear to play the predominant role in explaining variation in HAL.

Adolescent↗

PubMed1996

Validation of questionnaire and bronchial hyperresponsiveness against respiratory physician assessment in the diagnosis of asthma.

BACKGROUND: The Tasmanian Asthma survey (TAS) and the International Study of Asthma and Allergies in Childhood (ISAAC) have used questionnaires to measure the prevalence of asthma in adults and children. We have investigated the validity of these questionnaires by comparing response to questionnaire with a physician assessment of asthma status in the past 12 months. METHODS: Ninety-three adults were given the TAS questionnaire to complete and 361 children were given the ISAAC questionnaire. Ninety-one adults and 168 children completed bronchial challenge with hypertonic saline. A consultation with a respiratory physician blinded to the results of the questionnaire and bronchial challenge was given to all subjects. RESULTS: In both adults and children, questionnaires showed high agreement with respiratory physician diagnosis with respect to asthma symptoms in the past 12 months. For the TAS questionnaire the positive and negative predictive values (95% confidence limits) for physician diagnosis for adults were 0.89 (0.68-0.98) and 0.94 (0. 86-0.98) respectively. The instrument was also sensitive 0.80 (0. 58-0.93) and highly specific 0.97 (0.90-0.99). For the ISAAC questionnaire the positive and negative predictive vales for physician diagnosis of asthma in children were 0.61 (0.50-0.71) and 0.94 (0.88-0.98) respectively. Sensitivity and specificity were 0.85 (0.73-0.93) and 0.81 (0.76-0.86) respectively. Compared to the physician diagnosis, the sensitivity of bronchial hyperresponsiveness (BHR) for asthma was low for adults 0.39 (0.21-0. 61) and children 0.54 (0.48-0.67) as were the positive predictive values: 0.55 (0.31-0.79) for adults and 0.64 (0.449-0.77) for children. A definition of asthma requiring both a positive questionnaire response and BHR was highly specific but not sensitive for adults 0.37 (0.20-0.59) or children 0.47 (0.35-0.60). CONCLUSIONS: Both the TAS and ISAAC questionnaires are valid instruments for the determination of asthma symptoms in the past 12 months.

Adolescent↗

PubMed1996

Some public health issues in the current state of genetic testing for breast cancer in Australia.

Two genes associated with a high breast cancer risk (BRCA1 and BRCA2) have been discovered recently from study of large breast-cancer-dense kindreds. It is problematic to make inferences from these atypical families to the general population. Nevertheless, it appears that about 1 to 2 per cent of all breast cancer may be due to rare deleterious mutations in BRCA1 or BRCA2. The majority of breast cancer families with fewer than four cases are likely to have cancers not attributable to these genes. There may be more common mutations in other genes (such as ATM, HRAS1) that confer a moderate risk of breast cancer, and may account for 5 to 15 per cent of cases. At this early stage of cancer genetics, the risks associated with particular mutations are not known, there are no proven and acceptable strategies for women with an inherited susceptibility to ameliorate risk or improve prognosis, and risk estimates appropriate for Australian women with a family history of breast cancer are not established, although data from the United States may overestimate risk. Information is needed from population-based studies, such as the Australian Breast Cancer Family Study (Hopper et al. Breast 1994; 3: 79-86), but 100 per cent mutation detection in large cancer genes is difficult and expensive. Development of a systematic, research-oriented, evidence-based approach to genetic testing in Australia is recommended. Australia could lead the world in having common protocols used in breast cancer clinics across the country, linked to a national research consortium and database.

Australia↗

PubMed1996

Do genetic factors explain associations between muscle strength, lean mass, and bone density? A twin study.

Are the associations between muscle strength, lean mass, and bone mineral density (BMD) genetically determined? Based on within-pair differences in 56 monozygotic (MZ) and 56 dizygotic (DZ) female twin pairs, mean age 45 yr (range 24-67), BMD was associated with lean mass, independent of fat mass and height (P < 0.05). A 10% increment in femoral neck (FN) BMD was associated with a 15% increment in lean mass (approximately 6 kg). BMD was associated with muscle strength (measured in 35 pairs) before, but not after, adjusting for lean mass. Based on age-adjusted cross-sectional analyses, same-trait correlations (+/- SE) in MZ pairs were double those in DZ pairs: FN BMD (0.62 +/- 0.08, 0.33 +/- 0.12) and lean mass (0.87 +/- 0.03, 0.30 +/- 0.11; all P < 0.001), consistent with a genetic hypothesis. The cross-trait correlation (r) between lean mass and FN BMD in the same individual was 0.43 +/- 0.06. The cross-trait cross-twin correlation between lean mass in one twin and FN BMD in the other was 0.31 +/- 0.07 in MZ pairs, approximately 75% of the cross-trait correlation (r) and 0.19 +/- 0.09 in DZ paris (P < 0.001). After adjusting for height and fat mass, the MZ and DZ cross-trait cross-twin correlations were no different (0.16 +/- 0.08 and 0.13 +/- 0.09, respectively). Therefore, genetic factors account for 60-80% of the individual variances of both FN BMD and lean mass, and > 50% of their covariance. The association between greater muscle mass and greater BMD is likely to be determined by genes regulating size.

Adult↗

PubMed1996

Streptokinase increases luxury perfusion after stroke.

BACKGROUND AND PURPOSE: Recent acute stroke trials have reported that intravenous streptokinase is associated with an increased risk of adverse outcomes. We aimed to study the effect of streptokinase on the nature of reperfusion and the relation between reperfusion and clinical outcome. METHODS: We studied 24 patients in the Australian Streptokinase Trial with acute middle cerebral cortical infarction using 99mTc-hexamethylpropyleneamine oxime single-photon emission CT. Eleven of the 24 patients were scanned before therapy and again 24 hours later. The remaining 13 were scanned once either before therapy (1 patient) or after therapy (12 patients). All patients had outcome scans after 3 months. Infarct hypoperfusion was measured with a validated volumetric technique. Neurological impairment and functional outcome were assessed with the Canadian Neurological Scale and the Barthel Index, respectively. RESULTS: Fifteen patients received streptokinase and 9 received placebo. There was no difference in early reperfusion between streptokinase and placebo. However, streptokinase was associated with a greater amount of nonnutritional reperfusion than was placebo (P = .04). This luxury perfusion was associated with poor functional outcome (P = .02). CONCLUSIONS: This study suggests that streptokinase augments luxury perfusion after stroke. Luxury perfusion is associated with a worse outcome, which might be due in part to reperfusion injury.

Adult↗

PubMed1996

Bone turnover markers and bone density across the menopausal transition.

We measured lunbar spine and femoral neck bone mineral density (BMD); urine markers of bone resorption; serum markers of bone formation; and serum gonadotrophin, estradiol and inhibin concentrations in a population-based cohort of 281 women aged 45-57 yr. Women were classified into pre-, peri-, and postmenopausal groups, depending on menstrual bleeding patterns. Compared with premenopausal women, BMD was lower only in postmenopausal women but not in women currently using hormone replacement therapy (HRT). BMD decreased with age in the perimenopausal group. Compared with premenopausal women, perimenopausal women had 20% greater urine N-telopeptide excretion (P < 0.05) and a doubling of gonadotrophin levels (P < 0.01), whereas serum estradiol and bone formation marker concentrations were no different. Postmenopausal Women had greater levels of bone turnover markers (P < 0.0001), except free deoxypyridinoline and type I procollagen propeptide. Among postmenopausal women, bone resorption markers were lower in those using HRT. Levels of nearly all bone turnover markers were positively related to serum FSH concentrations (P < 0.0001). Overall, the major independent predictors of BMD were age, urine N-telopeptide, serum bone alkaline phosphatase, and serum, FSH, whereas urine free deoxypyridinoline was positively related to BMD in pre- and perimenopausal women. In conclusion, the perimenopause is associated with elevated bone resorption rates and declining BMD, and factors in addition to estrogen deficiency may also contribute to the pathogenesis of postmenopausal osteoporosis.

Aging↗