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Biomedical subjects

M Crutchfield

Publications and source records attributed to M Crutchfield.

18 recordsLinked to original sources
PubMed1998

Role of calciotrophic hormones in calcium mobilization of lactation.

The postpartum period can be a time when profound changes in calcium metabolism and bone mineral density (BMD) occur, particularly in association with lactation. We investigated the hypothesis that calciotrophic hormones [1,25-dihydroxyvitamin D, 25-hydroxyvitamin D, and parathyroid hormone (PTH)] are different by lactation practice or hormone status [PTH-related peptide (PTHrP), estradiol, and prolactin] and have a potential role in the bone loss and recovery associated with lactation. 1,25-Dihydroxyvitamin D, 25-hydroxyvitamin D, PTH, femoral BMD, PTHrP, prolactin, estradiol, and bone turnover markers were measured at 2 wk and at 2, 4, 6, 12, and 18 mo postparturition in 115 postpartum women aged 20-40 y (parity: 0-1). Lumbar spine BMD was measured at 2 wk and at 6, 12, and 18 mo during the postpartum period. PTH, 1,25-dihydroxyvitamin D, and 25-hydroxyvitamin D concentrations were nonlinear across the 18-mo postpartum period. Between baseline and 18 mo postparturition, PTH and 1,25-dihydroxyvitamin D concentrations did not decline, while there was a substantial decline in 25-hydroxyvitamin D concentrations. PTH, 1,25-dihydroxyvitamin D, and 25-hydroxyvitamin D concentrations did not differ by lactation practice or by PTHrP, estradiol, or prolactin status. These classic calciotrophic hormones were not associated with concentrations of bone turnover markers or changes in BMD in lactating women. In summary, patterns of change in calciotrophic hormones (PTH, 1,25-dihydroxyvitamin D, and 25-hydroxyvitamin D) in the 18-mo postpartum period appeared to be independent of PTHrP, estradiol, prolactin, or lactation status and were not associated with bone turnover markers. These data do not support the hypothesis that these three calciotrophic hormones are a central part of the calcium mobilization associated with the bone loss of lactation.

Adult↗
PubMed1998

Bone mineral density and its change in white women: estrogen and vitamin D receptor genotypes and their interaction.

Low bone mineral density (BMD) is a major risk factor for development of osteoporosis; increasing evidence suggests that attainment and maintenance of peak bone mass as well as bone turnover and bone loss have strong genetic determinants. We examined the association of BMD levels and their change over a 3-year period, and polymorphisms of the estrogen receptor (ER), vitamin D receptor (VDR), type I collagen, osteonectin, osteopontin, and osteocalcin genes in pre- and perimenopausal women who were part of the Michigan Bone Health Study, a population-based longitudinal study of BMD. Body composition measurements, reproductive hormone profiles, bone-related serum protein measurements, and life-style characteristics were also available on each woman. Based on evaluation of women, ER genotypes (identified by PvuII [n = 253] and XbaI [n = 248]) were significantly predictive of both lumbar spine (p < 0.05) and total body BMD level, but not their change over the 3-year period examined. The VDR BsmI restriction fragment length polymorphism was not associated with baseline BMD, change in BMD over time, or any of the bone-related serum and body composition measurements in the 372 women in whom it was evaluated. Likewise, none of the other polymorphic markers was associated with BMD measurements. However, we identified a significant gene x gene interaction effect (p < 0.05) for the VDR locus and PvuII (p < 0.005) and XbaI (p < 0.05) polymorphisms, which impacted BMD levels. Women who had the (-/-) PvuII ER and bb VDR genotype combination had a very high average BMD, while individuals with the (-/-) PvuII ER and BB VDR genotype had significantly lower BMD levels. This contrast was not explained by differences in serum levels of osteocalcin, parathyroid hormone, 1,25-dihydroxyvitamin D, or 25-dihydroxyvitamin D. These data suggest that genetic variation at the ER locus, singly and in relation to the vitamin D receptor gene, influences attainment and maintenance of peak bone mass in younger women, which in turn may render some individuals more susceptible to osteoporosis than others.

Absorptiometry, Photon↗
PubMed1998

Bone mineral density and its change in pre-and perimenopausal white women: the Michigan Bone Health Study.

There is a need to better understand potential bone mineral density (BMD) loss during the menopausal transition since this period may include the initiation of interventions. The study purpose was to determine if there was BMD loss at the femoral neck, lumbar spine, or total body bone sites in a population-based study of women approaching or transitioning the midlife. The 583 enrollees were 25-45 years of age at the first of four annual measurements from 1992 through 1996. Bone mineral content and bone width were measured using dual-energy X-ray absorptiometry. Considering all enrollees collectively, there was a significant 3-year decline (1%) in BMD at the femoral neck over the 3-year period (p = 0.076). There was no significant annual change in the lumbar spine (p = 0.11), and a significant annual increase in the total body BMD (p = 0.0003). Within subgroups and cross-sectionally, BMD values of the femoral neck were 5% lower in women classified as perimenopausal compared with premenopausal enrollees; BMD was 3% and 1% lower at the lumbar spine and total body site, respectively. Longitudinally, among perimenopausal women, a double oophorectomy was associated with BMD loss in the spine (p = 0.0003), even though 75-85% of these women had a hormone replacement prescription at some time during the study period. In summary, the site with evidence of loss was the femoral neck, specifically among perimenopausal women. There was little evidence of substantial total body or lumbar spine BMD loss in premenopausal women with ovaries who maintained follicle-stimulating hormone levels < 20 mIU/l in the early follicular period. Double oophorectomy, even with hormone replacement, was associated with bone loss.

Absorptiometry, Photon↗
PubMed1998

Urinary ovarian and gonadotropin hormone levels in premenopausal women with low bone mass.

We hypothesized that lower ovarian and gonadotropin hormone concentrations would be associated with lower levels of peak bone mineral density (BMD) in apparently normally menstruating women who did not exercise intensively and did not report anorexia or bulimia. This hypothesis was evaluated using a case-with-control study design (n = 65) which was nested within a population-based longitudinal study of peak bone mass (Michigan Bone Health Study) with annual assessment in women aged 25-45 years (n = 582). Cases were 31 premenopausal women with BMD of the lumbar spine, femoral neck, and total body less than the 10th percentile of the distribution, where controls were 34 premenopausal women with BMD between the 50th and 75th percentile. BMD was measured by dual-energy X-ray absorptiometry. In addition to their annual measurement, these 65 participants collected first-voided morning urine specimens daily through two consecutive menstrual cycles. The urine from alternating days of this collection was analyzed for estrone-3-glucuronide (E1G), pregnanediol glucuronide (PdG), testosterone, and follicle-stimulating hormone by radioimmunoassay and these values adjusted for daily creatinine excretion levels. Additionally, analyses of daily urine specimens for luteinizing hormone (uLH) was undertaken to better characterize the possible uLH surge. Cases had significantly lower amounts of E1G (p = 0.009) and PdG (p = 0.002) than did controls, whether amounts were characterized by a mean value, the highest value, or the area under the curve, and after statistically controlling for body size. Further, when B-splines were used to fit lines to the E1G and PdG data across the menstrual cycle, the 95% confidence intervals (CIs) about the line for the controls consistently excluded and excluded and exceeded the 95% confidence bands for the cases in the time frame associated with the luteal phase in ovulatory cycles. Likewise, 95% CIs for the LH surge in controls exceeded the fitted line for cases around the time associates with the LH surge. The cases and controls were not different according to dietary intake (energy, protein, calcium), family history of osteoporosis, reproductive characteristics (parity, age at menarche, age of first pregnancy), follicular phase serum hormone levels, calciotropic hormone levels, or by evidence of perimenopause. We conclude that these healthy, menstruating women with BMD at the lowest 10th percentile from a population-based study had significantly lower urinary sex steroid hormone levels during the luteal phase of menstrual cycles as compared with hormone levels in premenopausal women with BMD between the 50th and 75th percentile of the same population-based study, even after considering the role of body size. These data suggest that subclinical decreases in circulating gonadal steroids may impair the attainment and/or maintenance of bone mass in otherwise reproductively normal women.

Absorptiometry, Photon↗
PubMed1996

Elevated parathyroid hormone-related peptide associated with lactation and bone density loss.

OBJECTIVE: To investigate the hypothesis that parathyroid hormone-related peptide (PRHrP) may be involved with bone loss and recovery as a means of providing adequate calcium and phosphate to infants. DESIGN: An 18-month prospective cohort study. SETTING: General community setting with recruitment occurring at birthing education classes. PARTICIPANTS: Volunteer sample of 115 postpartum healthy women aged 20 to 40 years, and 0 or 1 parity prior to parturition with no intent to breast-feed or intent to breast-feed at least 6 months. MAIN OUTCOME MEASURES: Parathyroid hormone-related peptide, prolactin, estradiol, 1,25-dihydroxyvitamin D, 24-hydroxyvitamin D, femoral bone mineral density, and bone turnover markers were measured in 115 postpartum women at 2 weeks, 2 months, 4 months, 6 months, 12 months, and 18 months postpartum. Lumbar bone mineral density was measured at 2 weeks, 6 months, 12 months, and 18 months postpartum. RESULTS: Elevated PTHrP values were significantly associated (P<.001) with breast-feeding status, elevated prolactin levels, and lower serum estradiol levels, conditions occurring during lactation. Furthermore, elevated PTHrP levels were negatively and significantly associated (P<.01) over time with bone mineral density change at both the spine and the femoral neck, even after accounting for prolactin levels, breast-feeding status, return of menstruation, estradiol levels, PTH levels, 1,25-dihydroxyvitamin D levels, dietary calcium intake, physical activity, and body size. CONCLUSION: These data clearly support the hypothesis that PTHrP is an alternative mechanism associated with bone loss and recovery during and subsequent to lactation.

Absorptiometry, Photon↗
PubMed1996

Association of bone mineral density and sex hormone levels with osteoarthritis of the hand and knee in premenopausal women.

Mechanical stress on the cartilage and metabolic and/or hormonal influences have been suggested as possible etiologic factors for osteoarthritis. This paper reports findings from data collected in 1992 that were used to examine associations between osteoarthritis and risk factors in 573 Caucasian women aged 24-45 years from the Michigan Bone Health Study. Radiographs of the dominant hand and both knees were evaluated using the Kellgren and Lawrence grading scale. The prevalence of osteoarthritis (grade 2 or higher) in this population was 2.8% for hands and 3.6% for knees. Using polytomous multiple logistic regression, the authors found older age, increasing bone mineral density, and decreasing testosterone levels to be significantly associated with increasing hand scores. Older age and hand injury were significantly associated with grades of 2 or higher. Increasing osteoarthritis knee scores were associated with older age, increasing bone density, increasing body mass index, and current use of hormone replacement therapy. A knee grade of 2 or higher was associated with increasing estradiol levels, knee injury, and higher blood pressure. This study indicates that age, bone density, and injury are risk factors common to the development of hand and knee osteoarthritis in this non-elderly female population.

Adult↗
PubMed1995

Biochemical markers of bone turnover in lactating and nonlactating postpartum women.

We measured two bone-formation markers, osteocalcin and bone-specific alkaline phosphatase, and one bone-resorption marker, N-telopeptide, in a longitudinal study in order to describe levels of these markers in lactating and nonlactating women after parturition. This 18-month postpartum period included an initial 6 months in which a 5% short-term bone loss occurred at both spine and femoral neck among breast-feeding women. The second part of the 18-month period was characterized by bone recovery among women who had lost bone. These bone-change characteristics provided an opportunity to evaluate the performance of biochemical markers during both bone loss and recovery and to identify environmental exposures during lactation associated with bone turnover. The eligible population comprised 115 women whose bone-turnover markers were measured at 2 weeks (baseline) and at 2, 4, 6, 12, and 18 months after parturition. Participants reported reproductive characteristics, diet, physical activity, use of medications, and infant-feeding practices at each contact. Women were grouped according to lactation duration: 0-1 months, 2-5 months, and 6 months or more. Women who breast-fed for at least 6 months had significantly different levels of all three bone-turnover markers compared with the levels in bottle-feeding controls, which were indicative of substantially increased bone turnover. Factors that predicted the difference in biochemical markers from baseline to 6-month values by regression analysis were lactation of 2-6 months duration and lactation for 6 months or more. Dietary calcium intake, physical activity level, and body size did not explain the differences in the change from the baseline level to the 6-month level, a period of time that corresponded with bone loss in the lactating women. Factors that predicted the differences in bone-turnover markers between 6 and 18 months (the time of bone-mass recovery) were lactation status and number of months to resumption of menses. By the 18-month observation, there was no difference in the mean values for the measured bone-turnover markers among the three lactation groups. This suggests that menstrual activity, rather than diet or physical activity, is the primary factor in bone-mass recovery after the bone loss of lactation.

Adult↗
PubMed1992

Familiality and partitioning the variability of femoral bone mineral density in women of child-bearing age.

The contributions of polygenic loci and environmental factors to femoral bone mineral density (BMD) in g/cm2) variability were estimated in modified family sets consisting of women of child-bearing age. Femoral BMDs were measured in 535 women who were members of 137 family sets consisting minimally of an index, her sister, and unrelated female control. The family set could also include multiple sisters and first cousins. Women included in these family sets were all between 20 and 40 years of age to minimize the cohort effects of maturation and menopause on measures of BMD. BMDs were measured at three femoral sites using dual photon densitometry. Values were regressed on age and Quetelet Index which explained 13-15% of the variability in BMD (dependent on site). Subsequent variance components analysis on the residuals indicated that unmeasured polygenic loci accounted for substantial additional variability: 67% for femoral neck, 58% for Wards triangle, and 45% for trochanter. These results suggest that polygenic loci account for approximately half of the variability in maximal femoral BMD.

Adult↗
PubMed1991

Body composition, age and femoral bone mass of young adult women.

Maximum bone mineral density of the femur was measured by dual-photon densitometry in 282 healthy white women, aged 20 to 40 years. Femoral sites included the neck, Wards triangle, and the trochanter. Quetelet Index was used as a measure of weight adjusted for height, and body composition was measured using four-point bioelectrical impedance and anthropometry. Maximum bone mass is believed to be an important measure if the level established which remain characteristic or predict bone mineral density during the aging process. Body weight was correlated with each measure of femoral bone density, including the femoral neck (r = .42), Wards triangle (r = .34), and the trochanter (r = .44). Weight was more highly correlated with bone mass than with other measures of body composition, including fat-free mass, percent body fat, humeral muscle area, and humeral fat area. We observed that age was negatively associated with bone mass at all three femoral sites, even in subjects within the age range of 20 to 40 years, and the relationship was significant after controlling for Quetelet Index. There was no evidence of a nonlinear relationship that would indicate when maximal femoral bone mass reaches its peak within this age range.

Adult↗
PubMed1991

A prospective evaluation of bone mineral change in pregnancy.

During pregnancy, mineralization of the fetal skeleton creates a demand for approximately 30 g of calcium from maternal sources. We examined whether this fetal demand results in maternal femoral bone mineral loss. Femoral bone mineral density was measured twice by dual photon densitometry, once before conception and again within 15 days of parturition, in 32 white women aged 20-40 years. Femoral bone mineral density was also measured twice in 32 non-pregnant controls matched to the cases for weight, height, age, and parity. There was no significant mean bone mineral density loss in cases compared with controls (P greater than .63). Pregnant women with smaller body size, expressed as Quetelet index, were more likely to have femoral neck bone mass increase than their matched controls (P less than .03). This study provides evidence that fetal demand for calcium has a minimal effect on bone mineral density at parturition. Smaller women may experience a slight increase in femoral bone mineral density compared with controls.

Adult↗
PubMed1990

Sleepwalking, night terrors, and consciousness.

OBJECTIVE: To determine some personality and psychoneurotic characteristics of adults who have the sleepwalking-night terrors syndrome. DESIGN: Prospective assessment of two groups of consecutive patients with a firm diagnosis of either of two specific sleep disorders as established clinically and by polysomnography. SETTING: Outpatient sleep disorders clinic and sleep laboratory in a tertiary referral centre. PATIENTS: 12 Patients referred consecutively to the clinic in whom a diagnosis of sleepwalking (six) or night terrors (six) was confirmed. MAIN OUTCOME MEASURES: Psychological characteristics as measured at the time of clinical assessment by means of the Eysenck personality questionnaire, the hostility and direction of hostility questionnaire, and the Crown-Crisp experiential index. RESULTS: Both groups scored exceptionally highly on the hysteria scale of the Crown-Crisp experiential index and the night terrors group also scored highly on the anxiety scale. The patients with sleepwalking also scored highly on a measure of externally directed hostility. CONCLUSIONS: The physiological and psychological features identified in these patients, possibly reflecting different expressions of a constitutional cerebral characteristic, may be explored in terms of hysterical dissociation. The findings contribute to the debate concerning the nature of sleepwalking, in particular with and without the forensic aspects.

Adult↗
PubMed1987

Clomipramine and 'drive' in people with anorexia nervosa: an in-patient study.

Drugs can sometimes be helpful within the overall treatment and management of anorexia nervosa. In this study we have examined the impact of clomipramine on food and activity in anorectics engaged in a treatment programme enabling them to regain normal body weight. Consumption of the drug was associated with increased appetite, hunger and calorie consumption during the early stages of treatment. There was no impact on ultimate outcome. In this study it was evident that the drug was unnecessary for weight gain, but it may be helpful in other programmes, both short and long term, where the patient has sufficient trust (to tolerate the enhanced hunger experience) but is not involved in the same behavioural constraints. However, its possible value in such programmes has not been proven here. Meanwhile, we take our findings as further evidence that clomipramine increases drive behaviour and appetite in humans and may be beneficial in the treatment of affective disorders because of this effect.

Adolescent↗
PubMed1984

Vision symptoms with asteroid bodies in the vitreous.

Asteroid bodies in the vitreous present the doctor of optometry with a spectacular ophthalmoscopic view of numerous, minute yellow-white spheres in an otherwise normal vitreous. They have little or no association with systemic disease, and they are not often thought of as a cause for vision symptoms. We report four cases of vision symptoms that we believe were caused by asteroid bodies in the vitreous. The symptoms varied from minor impairments in visual acuity to floaters.

Aged↗
PubMedDate not supplied

Longitudinal changes in body composition in women approaching the midlife.

This population-based longitudinal study describes the 4.5-year changes in body composition and body mass distribution in women aged 20-45 years, and characterizes predictors of these changes. Body weight, waist-to-hip ratio, Quetelet index, fat and lean body mass were measured in 404 white menstruating women aged 20-40 at baseline and 4.5 years later (follow-up). Variables considered for predicting body composition differences were hormonal status, menstrual status, parity, diet and physical activity. Average body weight increased 4.3 kg in 4.5 years (6.4 kg increase in fat and 2.1 kg decrease in lean)--a net increase of 7.1% total body fat. Measured predictors were not significantly associated with weight or Quetelet index; however, they were associated with measured amounts of lean and fat. Longitudinally, women who preserved the most lean body mass tended to be nulliparous, to be still menstruating, to have higher testosterone levels, and to smoke. Physical activity was associated with preserving lean body mass. Increasing age and higher follicle-stimulating hormone levels were associated with increasing waist-to-hip ratio. Average body weight showed a steady increase--characterized by an expanding fat compartment and a shrinking lean compartment--with the older women increasing more in waist girth relative to hip girth than younger women. Predictor variables of these changes included hormonal environment, physical activity, smoking behaviour, parity, and oophorectomy.

Adipose Tissue↗
PubMedDate not supplied

The gap in your knowledge: gender on wheels.

Among a group of young car drivers the size of the gap perceived as necessary to allow them to drive their cars through was related to their degree of measured fatness. This relationship extended to measured height and shoulder breadth in women and self-perception of shoulder breadth in men. No relationship could be found with the premenstrual phase in women. These findings may have important social implications.

Adolescent↗
PubMedDate not supplied

Changes in bone density with lactation.

OBJECTIVE: To test the a priori hypotheses that significant bone loss occurs in lactation of greater than 5 months' duration and that bone mass returns to baseline levels when breast-feeding ceases. DESIGN: Prospective cohort study design of 12 months' duration. SETTING: General community setting with recruitment occurring at birthing education classes. PARTICIPANTS: Volunteer sample of 98 healthy women of white (n = 95) and Asian (n = 3) origin, aged 20 to 40 years, and 0 to 1 parity prior to parturition, grouped according to lactation duration: 0 through 1, 2 through 5, and 6 or more months. MAIN OUTCOME MEASURES: Bone mineral density (BMD) of the proximal femur was measured by dual-energy x-ray densitometry at 2 weeks (baseline), 2 months, 4 months, 6 months, and 12 months following parturition, and BMD of the lumbar spine was measured at baseline, 6 months, and 12 months after parturition. RESULTS: Women with lactation duration of 6 months or longer had mean BMD losses of 5.1% and 4.8% at the lumbar spine and femoral neck, respectively, comparing baseline values with those at 6 months post partum. Women who breast-fed 0 through 1 month lost no BMD at either bone site. Bone loss in women who breast-fed 6 months or longer was not explained by differences in age, diet, body size, or physical activity. Among women who breast-fed 6 months or longer, there was evidence of return to baseline levels of the lumbar spine at 12 months after parturition. The BMD of the lumbar spine of those women who continued to breast-feed more than 9 months had increased but was still significantly lower than baseline. CONCLUSION: Extended lactation (> or = 70% of energy intake is provided for > or = 6 months) is associated with bone loss; however, there is evidence of return to baseline BMD measurement at 12 months after parturition.

Absorptiometry, Photon↗