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Biomedical subjects

K T Khaw

Publications and source records attributed to K T Khaw.

At least 19 recordsLinked to original sources
PubMed1992

Bone density parathyroid hormone and 25-hydroxyvitamin D concentrations in middle aged women.

OBJECTIVE: To examine the relation between bone density and indices of calcium metabolism including parathyroid hormone and 25-hydroxyvitamin D concentrations in middle aged women. DESIGN: A cross sectional study. SETTING AND SUBJECTS: 138 women volunteers aged 45-65 with no known osteoporosis and unselected for disease status recruited for a dietary assessment study from the community using general practice registers. Volunteer rate was 20%. MAIN OUTCOME MEASURE: Bone mineral density measured with dual energy x ray absorptiometry. RESULTS: Bone density at the lumbar spine and neck and trochanteric regions of the femur was inversely related to serum intact parathyroid hormone concentrations and positively related to serum 25-hydroxyvitamin D concentrations. These associations were independent of possible confounding factors, including age, body mass index, cigarette smoking habit, menopausal status, and use of diuretics and postmenopausal hormone replacement therapy. These associations were apparent throughout the whole distribution of bone density and 25-hydroxyvitamin D and parathyroid hormone concentrations within the normal range, suggesting a physiological relation. CONCLUSIONS: The findings are consistent with the hypothesis that parathyroid hormone and 25-hydroxyvitamin D concentrations influence bone density in middle aged women. Findings from this study together with other work suggest that the role of vitamin D in osteoporosis should not be neglected. The associations with parathyroid hormone also indicate plausible biological mechanisms. The roughly 5-10% difference in bone density between top and bottom tertiles of serum 25-hydroxyvitamin D concentrations, though not large in magnitude, may have considerable public health implications in terms of prevention of osteoporosis and its sequelae, fractures.

25-Hydroxyvitamin D 2↗
PubMed1992

Sex hormones and postmenopausal breast cancer: a prospective study in an adult community.

Few studies have examined the role of endogenous sex hormones in breast cancer, and to the authors' knowledge, only two have done so prospectively. The authors report here the results of a prospective study based on an available bank of previously analyzed plasma collected in 1972-1974 from 442 women aged 50-79 years in Rancho Bernardo, California. These women were followed for 12-15 years, during which time 42 cases of breast cancer were identified: 15 incident cases diagnosed 1 year or more after baseline, 18 prevalent cases diagnosed earlier than 1 year after baseline, and 9 cases with unknown dates of onset. No apparent trends in plasma levels of sex hormones or sex hormone-binding globulin and incidence or prevalence of breast cancer were observed. Mean crude and age-adjusted plasma hormone levels at baseline (in pg/ml) for incident cases, total cases, and noncases, respectively, were: androstenedione: 647, 638 +/- 328 (standard deviation); 626, 620 +/- 245; and 664, 664 +/- 291; testosterone: 254, 258 +/- 120; 238, 241 +/- 153; and 262, 261 +/- 143; estrone: 37, 38 +/- 18; 35, 35 +/- 15; and 37, 37 +/- 17, and estradiol: 13, 13 +/- 7; 15, 15 +/- 8; and 15, 15 +/- 9. For sex hormone-binding globulin, mean crude and age-adjusted levels at baseline (nM) were 35 and 36 +/- 33 for incident cases; 31 and 31 +/- 25 for total cases; and 29 and 29 +/- 21 for noncases. Cox proportional hazards multiple regression showed no associations with breast cancer after simultaneous adjustment for age, body mass index, and cigarette smoking.

Aged↗
PubMed1992

Lower endogenous androgens predict central adiposity in men.

Central adiposity, sometimes described as male pattern fat distribution, is adversely related to cardiovascular risk and mortality independent of other measures of obesity. In a cohort of 511 men aged 30 to 79 years in 1972 to 1974, levels of androstenedione, testosterone, and sex hormone-binding globulin measured at baseline were inversely related to subsequent central adiposity, estimated 12 years later using the waist-hip circumference ratio. The observed differences in waist-hip ratio between top and bottom tertiles of these hormones and sex hormone-binding globulin were similar to mean waist-hip ratio differences between men with stroke or ischemic heart disease and those without in another prospective study. These findings, consistent with studies suggesting that testosterone seems to mobilize the abdominal depot on males, suggest that "male pattern" fat distribution may be a misleading description for central adiposity, at least, in men. Degree of maleness as indicated by total androgen levels is, in fact, negatively associated with central adiposity. However, the role of sex hormone-binding globulin in regulating androgenic activity warrants further investigation.

Adult↗
PubMed1992

Epidemiology of the menopause.

Profound changes in birth and mortality rates in this century are resulting in the ageing of the population of Britain and other developed countries. The enormous decline in maternal mortality, in particular, has meant that increasing proportions of women are surviving to the menopause and years of active life beyond it. Women aged 55 years and over now comprise 15% of the population of Britain. The average life expectancy for women in developed countries is around 75 years; approximately 90% of women reach the age of 65 years, and 30% reach 80 years. If the average age of menopause is 50 years, most women will spend approximately one third of their lifetime in postmenopausal life; one in every two women will experience about 30 years of postmenopausal life.

Adult↗
PubMed1992

Exogenous estrogen and endogenous sex hormones.

Estrogen replacement therapy is widely used to treat menopausal symptoms and prevent osteoporosis. The mechanism of these and other estrogen effects is currently under investigation. We studied the plasma steroid hormone and sex hormone binding globulin levels in frozen plasma obtained from 977 women aged 50 to 79 years from 1972 to 1974. Almost all of the 301 women who reported current use of noncontraceptive estrogen were taking conjugated estrogen by mouth; none reported use of a progestin. Women taking estrogen were significantly younger, thinner, and more likely to smoke cigarettes than women not taking estrogen. Sex hormone binding globulin and all endogenous hormones except testosterone were negatively correlated with age; estradiol was positively and cortisol and sex hormone binding globulin were negatively associated with obesity. After adjusting for age and obesity, dehydroepiandrosterone sulfate, androstenedione, and free testosterone were significantly lower in women currently taking estrogen than in women not using estrogen. These differences were independent of cigarette smoking. As expected, estrogens (including free estradiol), sex hormone binding globulin, and cortisol levels were higher in treated than untreated women. The possibility that some of the benefits and risks of replacement estrogen are secondary to altered adrenal steroid metabolism and androgen levels needs further evaluation.

Aged↗
PubMed1992

Body composition and bone mass in post-menopausal women.

OBJECTIVE: We aimed to assess total body composition and to study the interrelationships between fat and lean tissue mass with total and regional bone mass in healthy British post-menopausal women. DESIGN AND PATIENTS: Total body composition and regional bone mass were measured in 97 healthy post-menopausal women recruited from the general community. The mean age was 57.9 years, range 49-65. MEASUREMENTS: Total body composition (fat, lean tissue and bone mineral) and regional bone density in the lumbar spine and femur were measured by dual energy X-ray absorptiometry on a Lunar DPX. RESULTS: Significant negative correlations with age were found for total body bone mineral density (r = -0.200, P = 0.049), and lumbar spine bone mineral density (r = -0.28, P = 0.006); the calculated rate of bone loss from these two sites was 0.33 and 0.7% per annum respectively. Fat tissue mass showed a positive correlation with age (r = 0.22, P = 0.03). High correlations were observed between total body and regional bone mineral density (r = 0.755-0.829, P < 0.001). After adjustment for age and lean mass, statistically significant correlations were seen between fat tissue mass and all bone mass measurements (P < 0.01-0.001), the strongest correlations being found for total body bone mineral content and density (r = 0.477 and 0.488 respectively). Lean tissue mass showed a strong correlation with total body bone mineral content (r = 0.580, P < 0.001), after adjustment for age and fat mass; it was less strongly correlated with other bone mass measurements than fat mass, showing only weak correlations with total body, trochanteric and lumbar spine bone mineral density (r = 0.228-0.246, P < 0.05). Age-adjusted body weight showed stronger correlations with total and regional bone mass than did either body mass index or height. CONCLUSIONS: Both fat and lean tissue mass are related to total and regional bone mass in post-menopausal women, the relationship being strongest for fat mass. Body weight shows stronger correlations with bone mass than either height or body mass index. In view of the direction and magnitude of changes in fat, lean tissue and bone mineral after the menopause, adiposity and muscularity are more likely to be determinants of peak bone mass than of the rate of post-menopausal bone loss.

Absorptiometry, Photon↗
PubMed1992

Endogenous sex hormones and bone mineral density among community-based postmenopausal women.

In order to describe the relationships between endogenous sex hormones and bone mineral density in healthy postmenopausal women, we carried out a cross-sectional study of 90 community-based women, all at least one year since their last menstrual period (mean 9.6 +/- 4.9 years, range 1-22) and with a serum oestradiol level less than 100 pmol/l. None was currently using hormone replacement therapy. Serum oestradiol, testosterone, sex hormone binding globulin, dehydroepiandrosterone sulphate, and androstenedione were measured using standard techniques. Free oestradiol and testosterone indices were derived as the ratio of total hormone to sex hormone binding globulin, respectively. Total body, spine and hip bone mineral density (g/cm2) were measured by dual energy X-ray absorptiometry. Significant positive correlations were found between the free oestradiol and testosterone indices and bone mineral density at all sites. These relationships remained significant for the free oestradiol index after adjustment for age and body mass index. By stepwise multiple regression analysis, the free oestradiol index was an independent predictor of total body, spine and hip bone mineral density, accounting for 4-17% of the variance. These findings suggest an independent positive relationship between endogenous free oestradiol and total body, spine and hip bone mass even in the late postmenopause.

Aged↗
PubMed1991

Ultrasonic patterns in inflammatory bowel disease.

Ultrasound examination was performed in 90 patients with varying bowel pathology. Ultrasound reliably demonstrated thickening of the bowel. In addition, the pattern of abnormality seen in Crohn's disease and ulcerative colitis was different, and corresponded to the pathological changes seen in these disease processes. The pattern of bowel abnormality seen in other bowel diseases with an inflammatory aetiology generally corresponded to either the Crohn's or ulcerative colitic pattern. The appearances are described, together with findings in other non-neoplastic diseases of the bowel.

Colitis, Ulcerative↗
PubMed1991

Fasting plasma glucose levels and endogenous androgens in non-diabetic postmenopausal women.

1. The clinical association between glucose intolerance, hyperinsulinaemia, insulin resistance and hyperandrogenism is well recognized in premenopausal women with polycystic ovarian disease. We examined the hypothesis that fasting plasma glucose levels might be related to endogenous androgen levels in postmenopausal women in the absence of overt clinical disease. 2. In a Southern Californian cohort of 848 nondiabetic postmenopausal women aged 50-79 years, fasting plasma glucose levels positively correlated with levels of the endogenous androgens dehydroepiandrosterone sulphate and free testosterone and negatively with sex-hormone-binding globulin across the whole range of glucose and hormone levels. Mean dihydroepiandrosterone sulphate and free testosterone levels were 16% and 46% higher, respectively, and mean sex-hormone-binding globulin levels 27% lower in the top compared with the bottom quartile of fasting plasma glucose levels. This relationship was independent of age, body mass index, cigarette smoking habit and exogenous oestrogen use. 3. These findings raise questions about the possible physiological role of androgens in the regulation of glucose metabolism and insulin resistance and, possibly, in the mediation of the some of the cardiovascular consequences of diabetes in women.

Age Factors↗
PubMed1991

Neurosarcoidosis--demonstration of meningeal disease by gadolinium enhanced magnetic resonance imaging.

Arriving at a firm diagnosis of neurosarcoidosis continues to pose serious problems, particularly when evidence of granulomatous disease outside the nervous system is lacking. The commonest mode of presentation of neurosarcoidosis is with cranial nerve palsies. Two cases of presumed neurosarcoidosis with cranial nerve palsies showed clear evidence of focal meningeal disease on gadolinium-DTPA enhanced MRI brain scans. Although not specific for sarcoidosis, this technique may be very useful in aiding the diagnosis in suspected cases.

Aged↗
PubMed1990

Dehydroepiandrosterone sulfate and breast cancer risk.

It has been suggested that dehydroepiandrosterone (DHEA) and its sulfate ester, dehydroepiandrosterone sulfate (DHEAS), have a protective effect against breast cancer. In our investigation, DHEAS levels were measured in plasma obtained and frozen in 1972-1974 from 534 women aged 50-79 yr. This group, which has been followed for 15 yr, included 21 incident cases of breast cancer, 20 cases with earlier diagnosis, and ten cases with unknown date of onset who were identified from death certificates only. Two sets of analyses were done: one using all women and one which excluded women using estrogen. No significant differences in age-adjusted DHEAS levels were found between any case type and noncases. Age-adjusted rates of breast cancer by DHEAS tertile also showed no significant trends or differences among tertiles for any case type. A multivariate model in which the DHEAS level was adjusted for age, body mass index, estrogen use, and cigarette smoking status also showed no significant association between DHEAS and risk of breast cancer. These results do not support a protective role for plasma DHEAS in breast cancer risk in postmenopausal women.

Age Factors↗
PubMed1990

Multiple mutations in highly conserved residues are found in mildly affected cystic fibrosis patients.

We have identified three different point mutations in the coding region of the cystic fibrosis transmembrane conductance regulator (CFTR) gene. Each mutation segregates with the disease in two- or three-generation pedigrees and is not found on the normal chromosome of any documented cystic fibrosis carrier. One of the mutations is found in two independent families that contain at least one individual with a mild course of disease. All of these alterations replace charged amino acids with less polar residues and are found in the putative transmembrane sections of the molecule. The mutated amino acids are found to be conserved in both rodents and amphibians and lie in a region of CFTR that is believed to form a channel in the membrane. Although these alterations are rare, they provide important clues to functionally important regions of the molecule.

Adenosine Triphosphate↗
PubMed1990

The Kenyan Luo migration study: observations on the initiation of a rise in blood pressure.

OBJECTIVE: To demonstrate the magnitude, timing, and cause of changes in blood pressure that occur in migrants from a low blood pressure population on moving to an urban area. DESIGN: A controlled longitudinal observational study of migrants as soon after migration as possible and follow up at three, six, 12, 18, and 24 months after migration. A cohort of controls living in a rural area who were matched for age, sex, and locality were also observed at the same periods. SETTING: 35 Villages on the northern shores of Lake Victoria in western Kenya and Nairobi. PARTICIPANTS: 325 Members of the Luo tribe aged 15 to 34 years who had migrated to Nairobi and 267 controls living in villages. The numbers of both groups reduced during follow up such that only 63 migrants and 143 controls were followed up for two years. MAIN OUTCOME MEASURES: A medical questionnaire and three 24 hour diet histories were completed by migrants and controls. Height, weight, pulse, and blood pressure were measured. Three 12 hour overnight urine samples were collected from all participants and analysed for sodium, potassium, and creatinine concentrations. RESULTS: The mean systolic blood pressure of migrants was significantly higher than that of controls throughout the study, and the distribution of blood pressure was shifted to the right compared with controls. The mean diastolic blood pressure of the two groups diverged over time. Blood pressure differences were not due to selective migration. The migrants' mean urinary sodium:potassium ratio was higher than that of controls (p less than 0.001) throughout, and weight and pulse rate were also higher among migrants, although differences diminished with time. CONCLUSIONS: Urinary sodium:potassium ratio, pulse rate, and weight are important predictors of increased blood pressure among migrants from a low blood pressure community and may also be implicated in the initiation of essential hypertension.

Adolescent↗
PubMed1990

A prospective, population-based study of androstenedione, estrogens, and prostatic cancer.

Endogenous androgens have been suggested as determinants of risk of prostatic cancer. To examine this possibility, baseline sex hormone levels were measured in 1008 men ages 40-79 years who had been followed for 14 years. There were 31 incident cases of prostatic cancer and 26 identified from death certificates with unknown dates of diagnosis. In this study, total testosterone, estrone, estradiol, and sex hormone-binding globulin were not related to prostate cancer, but plasma androstenedione showed a positive dose-response gradient. Age-adjusted relative risks of prostatic cancer for low (0-2.2 nM), middle (2.3-3.1 nM), and high (3.2+ nM) tertiles of androstenedione were 1.00, 1.34, and 1.98, respectively (P trend less than 0.05). The linear gradient of risk persisted after adjustment for age and body mass index. If confirmed, these data suggest that androstenedione might increase the occurrence of clinically manifest prostatic cancer.

Adult↗
PubMed1990

Does lithium carbonate affect the ion transport abnormality in cystic fibrosis?

Lithium is known to affect several aspects of cellular regulation which may be related to ion channel function in epithelial cells. To determine whether the ion transport abnormality in cystic fibrosis (CF) is affected by lithium with resultant changes in clinical status, 36 CF patients, 12-37 years old, were enrolled in a 14 week, double-blind, placebo-controlled trial. Eighteen patients were randomly assigned to receive lithium carbonate for 10 weeks. At the end of therapy their average serum lithium concentration was 0.56 +/- 0.06 mmol (SEM) per liter. Their sweat chloride concentration fell from 92.1 +/- 4.8 mmol per liter to 87.4 +/- 4.0 mmol per liter after 10 weeks of therapy (P = 0.07) and rose to 94.4 +/- 3.5 mmol per liter 4 weeks after end of therapy (P less than 0.001 compared to results at end of therapy). Their forced vital capacity (FVC) fell from 72 +/- 5.3% of predicted to 66 +/- 5.1% of predicted after 4 weeks of therapy (P less than 0.01), and their forced expiratory volume in one second (FEV1) fell from 56 +/- 5.5% of predicted to 51 +/- 5.5% of predicted after 4 weeks of therapy (P less than 0.01). In a non-blind assessment, performed 19 weeks after the end of therapy, their FVC and FEV1 had risen and were not significantly different from baseline. Sweat chloride, FVC, and FEV1 remained unchanged in the placebo group throughout the period of study.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1990

Ultrasound guided fine needle aspiration of ovarian cysts: diagnosis and treatment in pregnant and non-pregnant women.

Ovarian cysts are conventionally managed by laparoscopy or laparotomy. Twenty-two patients underwent fine needle aspiration of ovarian cysts under ultrasound control. Four patients were pregnant, and in two of these, aspiration of the cyst was performed transvaginally. The aspirate was examined cytologically and correlated with histology where available. The technique and results are discussed. No complications occurred. It is concluded that fine needle aspiration under ultrasound guidance is simple, safe and useful in the management of ultrasonically benign unilocular ovarian cysts in pre-menopausal women. It is of particular use in pregnancy, and in patients unsuitable for laparoscopy or surgery. Surgery can be reserved for cysts which recur after aspiration, cysts with a haemorrhagic aspirate, cysts in post-menopausal women and those with ultrasonic criteria of malignancy.

Adult↗