PubMed Health⌕ Search

Biomedical subjects

J C Prior

Publications and source records attributed to J C Prior.

At least 37 records · Page 2Linked to original sources
PubMed1997

Premenopausal ovariectomy-related bone loss: a randomized, double-blind, one-year trial of conjugated estrogen or medroxyprogesterone acetate.

The purpose of this study was to contrast the effects of conventional estrogen treatment with medroxyprogesterone on cancellous and cortical bone change in the first year following premenopausal ovariectomy. This 1-year double-blind randomized therapy trial was stratified by osteoporosis family history and performed in an academic medical center and community hospitals. Premenopausal women 45 +/- 5 years old, postovariectomy for benign diseases were provided 600 mg/day of calcium and randomized to daily therapy with conjugated equine estrogen (CEE, 0.6 mg) or medroxyprogesterone (MPA, 10 mg). The primary outcome variable was spinal quantitative computed tomography (QCT) bone density change over 1 year with additional outcomes of dual-energy X-ray absorptiometry (DXA) of proximal femur (FN), whole body (WB), and spine segment (WBS) and N-telopeptide, bone-specific alkaline phosphatase, and other bone marker, hormonal, and weight changes. Results in the 33 women completing the study, whose initial bone densities were normal (QCT 133 mg/cm3, femoral neck 0.94 g/cm2, whole body DXA 1.13 g/cm2), showed annual QCT loss during CEE therapy of -11.5 mg/cm3 (p < 0.0007) and MPA bone loss of -19.7 mg/cm3 (p < 0.0001). Losses were marginally greater on MPA than CEE (p = 0.04). Extremely high postovariectomy (5 days) and pretreatment resorption markers (> 3 SD above premenopausal normal levels) were significantly related to bone loss. Across the year, resorption decreased during CEE but increased on MPA treatment. Significant DXA bone losses were prevented by CEE treatment (-1.4% FN, -.4% WB, and -1.5% WBS, all NS). However, DXA bone loss was not prevented by MPA treatment (-5% FN, -2.8% WB, and -6.1% WBS, all p < 0.03). Average weight gain was significant (+ 3.2 +/- 4.0 kg) and greater on CEE than MPA (+ 4.7 vs. + 2.0 kg, p = 0.049). In conclusion, CEE therapy did not prevent significant 8% cancellous spinal bone loss in the first year following premenopausal ovariectomy, despite supplementation with 600 mg/day of calcium, good control of vasomotor symptoms, and nearly 5 kg of gain in weight. Significant DXA bone loss, however, was prevented by CEE, but not by MPA therapy. These unexpected results were statistically related to high bone resorption following ovariectomy, which CEE suppressed but MPA did not. Bone formation markers increased during MPA therapy but were unchanged during CEE therapy.

Absorptiometry, Photon↗
PubMed1996

Prevention and management of osteoporosis: consensus statements from the Scientific Advisory Board of the Osteoporosis Society of Canada. 5. Physical activity as therapy for osteoporosis.

OBJECTIVE: To examine exercise as a therapy for people with osteoporosis. OPTIONS: Immobilization, standing low-load and high-load physical activities. OUTCOMES: Risk of injury, quality of life, risk of falls and fractures, strength and posture and pain management. EVIDENCE: Relevant epidemiologic studies, clinical trials and reviews were examined, including the large-scale FICSIT trial in the United States, a prospective 4-year study of women enrolled in an exercise program in Toronto and the large-scale Study of Osteoporotic Fractures. VALUES: Minimizing risk of injury and increasing quality of life were given a high value. BENEFITS, HARMS, AND COSTS: Moderate physical activity in people with osteoporosis can reduce the risk of falls and fractures, decrease pain and improve fitness and overall quality of life. It may also stimulate bone gain and decrease bone loss. Its positive effects are an adjunct to other interventions, such as hormonal therapy. It may give patients the confidence to resume regular activity and can provide social interaction and support. During exercise programs, proper nutrition is necessary to prevent excessive weight loss and impaired immune function resulting from inadequate protein, vitamin and mineral intake. RECOMMENDATIONS: Immobilization should be avoided if possible in anyone with osteoporosis or at increased risk for osteoporosis. Regular, moderate physical activity is recommended for those with osteoporosis. Elderly people should be assessed for risk of falling to identify those in greatest need of an exercise program. Community group exercise programs are beneficial. Younger people with osteoporosis also need exercise that will preserve or improve bone mass, muscular strength, endurance and cardiovascular fitness. Weight loss as a result of physical activity should be avoided and adequate intake of protein, vitamins and minerals assured. Because the benefits of physical activity are independent of the effect of other therapies, physical activity is an essential adjunct to appropriate nutrition and other therapies. VALIDATION: These recommendations were developed by the Scientific Advisory Board of the Osteoporosis Society of Canada at its 1995 Consensus Conference. They are in agreement with the position taken on osteoporosis and exercise by the United States Center for Disease Control and Prevention and the American College of Sports Medicine. SPONSORS: Sponsors of the 1995 conference included the Dairy Farmers of Canada, Eli Lilly Canada, Inc., Hoffmann-La Roche Canada Ltd., Merck Frosst Canada Inc. and Procter & Gamble Pharmaceuticals Canada Inc.

Accidental Falls↗
PubMed1996

Ovulatory premenopausal women lose cancellous spinal bone: a five year prospective study.

Healthy premenopausal women with regular cycles are believed to be increasing or maintaining bone density. However, few studies have prospectively documented spinal cancellous bone, the bone that changes rapidly in response to reproductive hormones, in this population. Furthermore, our previous one-year study documented that 24% of the one-year bone change by quantitative computed tomography (QCT) was related to subclinical ovulatory disturbances (short luteal phase and non-ovulation) in the presence of regular menstrual cycles. The purpose of this study was to document the cancellous bone change over five years in this initially ovulatory, premenopausal cohort of 66 healthy women. Thirty-seven women, who continued to be premenopausal and have regular cycles, completed this five-year study. Those enrolled differed only by being older and weighing less than those who could not be contacted (n = 19) or who declined to participate (n = 10). Documentation of current ovulatory characteristics was obtained for at least three cycles in 27 women. At the five-year assessment, the volunteers were 40.6 (range 26-47) years old, weighed 58.5 (41-77) kg, and were 160.9 (149-174) cm in height. All were premenopausal, healthy, nonsmokers with regular menstrual cycles (mean 27.7, range 24-33 days). Six women with intervening events (such as pregnancy or use of oral contraceptives) had interval (12 to 60 months) QCT changes similar to the remaining 31 (-7.98 vs. -4.92 mg/cm, p = 0.1, respectively). Mean five-year QCT was 143.0 +/- 20.2 mg/cm, whereas the initial mean value was 151.9 +/- 20.1 mg/cm. Significant QCT loss over five years (-8.9 +/- 6.2 mg/cm) (95% Cl -6.9 to -11.0) correlated with QCT change in the first year (r = 0.629, p < 0.001). First-year change was not related to the subsequent four-year interval change (r = -0.056, p = 0.74), however. Five-year QCT change was not related to age, weight, osteoporosis family history, estimated calcium intake, or exercise, but did correlate with year one luteal index (luteal/cycle length) (r = 0.339, p = 0.043). Significant cancellous spinal bone loss occurs in healthy, ovulatory premenopausal women, and is influenced by subclinical disturbances of ovulation.

Adult↗
PubMed1995

Energy intakes are higher during the luteal phase of ovulatory menstrual cycles.

We compared energy and macronutrient intakes across the menstrual cycle in participants (n = 42) in a study that assessed the frequency of ovulatory disturbances in regularly cycling vegetarians and nonvegetarians. Women kept daily basal body temperature records for six consecutive menstrual cycles and provided 3-d diet records near the beginning, middle, and end of different cycles. On completion of the study, temperature records were quantitatively analyzed to determine whether cycles were ovulatory, and if so, the date the luteal phase began. Diet records kept near the beginning and end of cycles were matched with temperature analysis results, and women were grouped according to whether the end-of-cycle record was kept during the luteal phase of an ovulatory cycle (group 1, n = 29), or during an anovulatory cycle or before luteal phase onset of a short luteal phase cycle (group 2, n = 13). Group 1 had higher energy intakes during the luteal than during the follicular phase (9.27 +/- 2.69 vs 8.01 +/- 2.36 MJ/d, P < 0.0001), whereas intakes of group 2 did not differ across the cycle (7.91 +/- 2.18 vs 8.20 +/- 1.48 MJ/d, NS). Both groups' macronutrient intakes were similar in records kept near the beginning and end of cycles. Documentation of ovulation is necessary in studies assessing premenopausal women's energy intakes.

Adult↗
PubMed1995

Medroxyprogesterone increases basal temperature: a placebo-controlled crossover trial in postmenopausal women.

OBJECTIVE: To assess whether temperature is increased by medroxyprogesterone (MPA) and thus whether basal temperature records could be used to determine ovulation during cyclic MPA therapy. DESIGN: A 2-month double-blind placebo-controlled crossover trial in which oral basal temperature was measured daily. SETTING: Normal human volunteers in an academic medical environment. SUBJECTS: Eleven postmenopausal women not taking gonadal hormones. INTERVENTION: Medroxyprogesterone acetate (10 mg/d) or placebo, calendar days 16 to 25, with crossover. MAIN OUTCOME MEASURES: Comparison of mean temperature days 17 to 26 during MPA versus placebo; comparison of differences between temperatures days 7 to 16 and 17 to 26 in MPA versus placebo months; and analysis for a significant monthly thermal shift. RESULTS: The mean temperatures during MPA treatment averaged 0.27 degrees C higher than during the placebo phase and showed a significant change from pretreatment to "treatment" phases during MPA but not during placebo cycles. Eight of the MPA and one of the placebo cycles showed a shift from lower to higher temperatures days 16 to 25. CONCLUSIONS: Medroxyprogesterone acetate has a physiological progesterone-like thermal effect. Therefore basal temperature data cannot reliably indicate ovulation during cyclic MPA administration.

Adult↗
PubMed1995

Effects of menstrual cycle phase on athletic performance.

The purpose of this study was to examine the effects of menstrual cycle phase on four selected indices of athletic performance: aerobic capacity, anaerobic capacity, isokinetic strength, and high intensity endurance. Sixteen eumenorrheic women (VO2max > or = 50 ml.kg-1.min-1) were tested during the early follicular (F) and midluteal (L) phases of the menstrual cycle. Cycle phases were confirmed by serum estradiol and progesterone assays. No significant differences were observed between F and L tests in weight, percent body fat, sum of skinfolds, hemoglobin concentration, hematocrit, maximum heart rate, maximum minute ventilation, maximum respiratory exchange ratio, anaerobic performance, endurance time to fatigue (at 90% of VO2max), or isokinetic strength of knee flexion and extension. Both absolute and relative VO2max, however, were slightly lower in L than in F (F = 3.19 +/- 0.09.min-1, L = 3.13 +/- 0.08.min-1, P = 0.04; and F = 53.7 +/- 0.9 ml.kg-1.min-1, L = 52.8 +/- 0.8 ml.kg-1.min-1, P = 0.06). These results suggest that the cyclic increases in endogenous female steroid hormones of an ovulatory menstrual cycle may have a slight, deleterious influence on aerobic capacity, with potential implications for individual athletes. Nevertheless, the cycle phase did not impact significantly on the majority of the other performance tests and cardiorespiratory variables measured in this study.

Adipose Tissue↗
PubMed1994

Cyclic medroxyprogesterone treatment increases bone density: a controlled trial in active women with menstrual cycle disturbances.

OBJECTIVE: Bone loss occurs in young women who experience amenorrhea or ovulatory disturbances. The purpose of this study was to determine whether bone loss could be prevented by simulating a more normal hormonal pattern, using treatment with cyclic medroxyprogesterone, with or without calcium supplementation, in physically active women with disturbed menstruation. DESIGN: This study was a 1-year randomized, double-blind, placebo-controlled trial. Women who were stratified by menstrual cycle disturbance were randomized into four groups. The outcome variable was the change in spinal bone density measured by dual energy techniques. SETTING: A large metropolitan area. PARTICIPANTS: Sixty-one healthy, normal-weight physically active premenopausal women aged 21 to 45 years who experienced amenorrhea, oligomenorrhea, anovulation, or short luteal phase cycles completed the study. INTERVENTION: Therapies were cyclic medroxyprogesterone (10 mg/day for 10 days per month) and calcium carbonate (1,000 mg/day of calcium) in four groups: (A) (n = 16) cyclic medroxyprogesterone plus calcium carbonate; (B) (n = 16) cyclic medroxyprogesterone with calcium placebo; (C) (n = 15) placebo medroxyprogesterone with active calcium; or (D) (n = 14) both medroxyprogesterone and calcium placebos. RESULTS: The initial bone density (mean = 1.12 g/cm2) did not differ by group (P = 0.85). The 1-year bone density change was strongly related to treatment with medroxyprogesterone (P = 0.0001) and weakly to calcium (P = 0.072) treatment. Bone density increased significantly (+1.7% +/- 0.5%, +/- SEM, P = 0.004) in the medroxyprogesterone-treated groups (A and B), did not change in the calcium-treated group (C) (-0.7% +/- 0.6%, P = 0.28), and decreased on both placebos (D) (-2.0% +/- 0.6%, P = 0.005). CONCLUSIONS: Cyclic medroxyprogesterone increased spinal bone density in physically active women experiencing amenorrhea or ovulatory disturbances. POTENTIAL CLINICAL SIGNIFICANCE: Amenorrhea, oligomenorrhea, anovulation, and short luteal phase cycles are common in premenopausal women and associated with spinal bone loss occurring at a stage of life when bone density would normally be stable or increasing. This controlled trial shows a significant gain in bone in women in the cyclic medroxyprogesterone intervention group, whereas those subjects in the placebo group lost bone. Calcium supplementation appeared to be helpful but did not reach statistical significance. The implications of these findings for the prevention of osteoporosis warrant further investigation.

Adult↗
PubMed1994

Restrained eating and ovulatory disturbances: possible implications for bone health.

We assessed the relationship between dietary restraint and menstrual cycle characteristics in 27 ovulatory women, previous participants in a longitudinal study of spinal cancellous bone mineral density (BMD). Subjects completed the restraint scale of the Three Factor Eating Questionnaire, recorded basal temperature and exercise for at least three menstrual cycles, and completed a 3-d food record. Cycle lengths of women in the upper and lower tertiles of scores for restraint were similar [27.8 +/- 1.0 (mean +/- SE) vs 27.6 +/- 0.8 d], but luteal phase length was shorter in the former group (8.6 +/- 0.9 vs 10.8 +/- 0.5 d, P < 0.05). Age, body mass index, percent body fat, waist-hip ratio, reported energy intake, and activity were similar between groups. Because the previous longitudinal study found associations between ovulatory disturbances and bone loss, we assessed spinal BMD using dual-energy x-ray absorptiometry (DXA) and quantitative computed tomography (QCT). BMD of women in upper and lower restraint tertiles, respectively, did not differ: DXA, 1.15 +/- 0.05 vs 1.20 +/- 0.06 g/cm2; and QCT, 140 +/- 7 vs 133 +/- 7 mg/cm3. Additional prospective studies, however, appear warranted. In conclusion, this study's results provide evidence that high dietary restraint is associated with a shortened luteal phase length.

Adult↗
PubMed1994

Vegetarian vs nonvegetarian diets, dietary restraint, and subclinical ovulatory disturbances: prospective 6-mo study.

Ovulatory function was prospectively assessed over 6 mo in 23 vegetarians and 22 nonvegetarians with clinically normal menstrual cycles. Subjects were 20-40 y of age, of stable weight (body mass index, in kg/m2, of 18-25), on current diets for > or = 2 y, and not using oral contraceptives. Quantitative analysis of basal body temperature records classified cycles as normally ovulatory, short luteal phase (< 10 d), or anovulatory. Subjects completed the Three-Factor Eating Questionnaire (subjects completed the Three-Factor Eating Questionnaire (subscales for restraint, hunger, and disinhibition) and kept three 3-d food records. Vegetarians had lower BMIs (21.1 +/- 2.3 vs 22.7 +/- 1.9, P < 0.05), percentage body fat (24.0 +/- 5.5% vs 27.4 +/- 5.1%, P < 0.05), and restraint scores (6.4 +/- 4.4 vs 9.5 +/- 3.7, P < 0.05). Mean cycle lengths were similar, but vegetarians had longer luteal phase lengths (11.2 +/- 2.6 vs 9.1 +/- 3.8 d, P < 0.05). Cycle types also differed (chi 2 = 9.64, P < 0.01): vegetarians had fewer anovulatory cycles (4.6% vs 15.1% of cycles). Compared with those with restraint scores below the median, highly restrained women had fewer ovulatory cycles (3.6 +/- 2.3 vs 5.0 +/- 1.4, P < 0.05) and shorter mean luteal phase lengths (7.4 +/- 4.1 vs 10.7 +/- 3.1 d, P < 0.05). We conclude that ovulatory disturbances and restrained eating are less common among vegetarians, and that restraint influences ovulatory function.

Adult↗
PubMed1994

Serum lactogens possessed normal bioactivity in patients with lactation insufficiency.

OBJECTIVE: Insufficient breast milk is the most common reason for premature termination of breast-feeding. The causes of lactation insufficiency are usually multifactorial; in a small percentage of cases it is due to primary lactation failure of unknown origin. The aim of this study was to investigate whether lactation insufficiency of unknown origin could be caused by serum lactogens that had reduced biological activity. DESIGN: Women with lactation insufficiency of unknown origin and normal lactating controls were subjected to a standardized breast-feeding test for assessment of milk production. Thirty minutes later, serum samples were obtained for determination of total lactogen bioactivity, using an in-vitro bioassay, and levels of prolactin (PRL) and growth hormone (GH) using radioimmunoassay (RIA). PATIENTS: Twelve lactating mothers with a clinical diagnosis of lactation insufficiency of unknown origin were compared with 12 matched mothers with normal lactation. MEASUREMENTS: The Nb2 lymphoma cell bioassay was used to measure total lactogen bioactivity in sera. Conventional RIA kits were used to estimate serum PRL and GH concentrations. RESULTS: Mean milk yield on standardized test feed was 21.6 ml for patients and 146.5 ml for controls. In both patient and control groups the total serum lactogen bioactivity ranged from about 150 to 5000 mIU/l, while the serum RIA (PRL+GH) levels ranged from about 350 to over 7000 mIU/l. There was no evidence of lactogens with reduced bioactivity in the patients' sera. CONCLUSION: Lactation insufficiency in the women studied cannot be explained by serum lactogens that possess unusually low bioactivity.

Biological Assay↗
PubMed1994

No adverse effects of medroxyprogesterone treatment without estrogen in postmenopausal women: double-blind, placebo-controlled, crossover trial.

OBJECTIVE: To determine whether cyclic medroxyprogesterone treatment given without estrogen causes adverse symptoms in postmenopausal women. METHODS: This was a placebo-controlled, double-blind, crossover trial of 10 days/month of medroxyprogesterone and placebo treatments given during 2 consecutive months in random order. Participants recorded their physiologic and emotional experiences on a 0-4 scale using a daily diary form. Eleven postmenopausal women aged 43-63 completed the study. The subjects were not taking hormones. Height, weight, and serum estradiol concentration were measured once. In each woman, the sum of scores for the 10 days of medroxyprogesterone was compared to the sum of scores for the 10 days of placebo using nonparametric tests. RESULTS: No significant differences in scores were found between the 10 days on medroxyprogesterone and the 10 days on placebo. The median and range for the composite scores for premenstrual-like symptoms were 26 (20-67) during medroxyprogesterone and 25 (19-40) during placebo (P = .39). CONCLUSIONS: Medroxyprogesterone given alone does not cause adverse symptoms in postmenopausal women. Therefore, medroxyprogesterone therapy, by itself, cannot explain the side effects reported by postmenopausal women taking combined hormones.

Adult↗