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Biomedical subjects

M E Nelson

Publications and source records attributed to M E Nelson.

87 records · Page 5Linked to original sources
PubMed1988

Hormone and bone mineral status in endurance-trained and sedentary postmenopausal women.

Serum hormone levels and bone mineral status were studied in 18 sedentary and 15 endurance-trained postmenopausal women (mean age, 62 yr). The endurance-trained women had lower body weight, lower body fat, and higher aerobic capacity than the sedentary women (P less than 0.05). There were no differences in current calcium intake between the 2 groups, as assessed by a 7-day food record, but carbohydrate intake (grams per kg BW) was higher in the endurance-trained women (P less than 0.001). Bone mineral density (BMD) of the spine (L1-L3), proximal femur, and radius did not differ between the 2 groups; however, when normalized for body weight, the BMDs of the spine and radius were higher in the endurance-trained than in the sedentary women. Serum estrone and PTH levels were lower, and 1,25-dihydroxyvitamin D and somatomedin-C levels were higher in the endurance-trained than in the sedentary women. Serum GH tended to be higher in the endurance-trained than in the sedentary women (P = 0.08), and there was a postexercise increase in serum GH in the endurance-trained, but not in the sedentary, women (P less than 0.01). The major effect of habitual exercise was on body weight and hormone status. Although leanness and low serum estrone levels are risk factors for osteoporosis, these were not associated with lower BMD in endurance-trained women. Endurance-trained women may have improved calcium absorption as a result of higher carbohydrate intake and higher serum 1,25-dihydroxyvitamin D levels.

Adult↗
PubMed1987

Counteracting the effects of mydriatics. Does it benefit the patient?

The effect of 2% pilocarpine nitrate in countering mydriasis, cycloplegia, and change in visual acuity due to 0.5% tropicamide was studied in 23 healthy volunteers. There was no significant difference in the decrease in pupil size or the rate of return of accommodation between the eye that received pilocarpine and the control eye. The effect of tropicamide on visual acuity was slight. In four (17%) of 23 eyes that received pilocarpine, visual acuity was reduced to 6/36 or worse. It is suggested that the use of 2% pilocarpine in the attempted reversal of 0.5% tropicamide to improve a patient's vision is not helpful and may possibly be harmful.

Accommodation, Ocular↗
PubMed1986

Diet and bone status in amenorrheic runners.

Our purpose was to determine the relationship of diet, exercise, and amenorrhea with bone mineral status in trained young women. Bone mineral density of the lumbar spine was significantly lower in amenorrheic compared to normally menstruating runners. Circulating estradiol was also significantly lower. No significant differences between the two groups were found in body composition, maximum aerobic power, or amount of training per week. A 3-day dietary record showed that the amenorrheic women reported a significantly lower daily energy intake, but no difference in the calcium intake. Protein intake was less than the US Recommended Dietary Allowance in 82% of amenorrheic women and 35% of eumenorrheic women. Abnormal eating behaviors may be associated with the development of amenorrhea. Our results show that when weight-bearing exercise and a low energy intake are associated with amenorrhea, the accretion of a large bone mass in young trained women is not favored.

Adult↗
PubMed1986

Bone mineral content and levels of gonadotropins and estrogens in amenorrheic running women.

Serum gonadotropin and estrogen levels and their relationship to bone mineral content in exercise-related amenorrhea were studied in 11 amenorrheic women and 24 eumenorrheic women, all of whom were runners. Serum estradiol, LH, FSH, estrone, and testosterone were measured in serial blood samples obtained at 15-min intervals for 4 h. The amenorrheic women had lower estradiol, LH, FSH; and estrone levels as well as a higher estrone-estradiol ratio than did the eumenorrheic women. There was no difference in testosterone levels. The amenorrheic women had lower LH pulse amplitudes, whereas no differences were found in FSH pulse amplitudes. LH and FSH pulse frequencies did not differ between the two groups. Bone mineral content of the lumbar spine was lower in amenorrheic women and was positively correlated with estradiol levels in all women. There was no difference in bone mineral content of the radius. These data suggest that, in exercise-related amenorrhea, low serum LH, FSH, and estrogen levels reflect an alteration in the hypothalamic control of gonadotropin release. Reduced circulating estrogen levels in amenorrheic running women may be a cause of low mineral content of the spine.

Adult↗
PubMedDate not supplied

Spatial heterogeneity of mitochondrial DNA and allozymes among populations of white-tailed deer and mule deer.

A white-tailed deer (Odocoileus virginianus) population in northeastern Minnesota and a mule deer (O. hemionus) population in the Bridger Mountains Montana, have previously been shown to be spatially subdivided into contiguous subpopulations. We assessed the degree of genetic differentiation among subpopulations and tested the hypothesis that differentiation will be greater for mitochondrial DNA (mtDNA) than for nuclear-encoded allozymes. Differentiation of the white-tailed deer subpopulations was significant for two allozyme loci but not for mtDNA, and the overall degree of differentiation was low. Gene flow, recent founding of the subpopulations, and polygamous breeding structure may all have contributed to this pattern. Greater differentiation was evident among disjunct populations than between the contiguous subpopulations of white-tailed deer. The contiguous mule deer subpopulations were significantly differentiated for mtDNA and one allozyme locus. Differentiation was greater for mtDNA than for allozymes. These results are consistent with demographic data that indicate mule deer males disperse more than do females. Disjunct mule deer populations may be similar or dramatically different in mtDNA haplotype frequencies that do not necessarily vary with geographic distance. Current and historical gene flow and breeding structure will influence population genetic patterns.

Animals↗
PubMedDate not supplied

Prevalence of Chlamydia trachomatis infection among women in a multiphysician primary care practice.

I screened 312 women, 18-45 years of age, presenting for routine gynecologic examination or prenatal care in a multiphysician primary care practice for Chlamydia trachomatis and Neisseria gonorrhoeae. I evaluated age, pregnancy, payment status, and presence of clinical cervicitis or gonorrhea as possible predictors of risk for chlamydial infection. Compared to culture, the direct immunofluorescent antibody (DFA) test used to screen for C trachomatis had a sensitivity of 70% and a specificity of 97%. By culture, the overall prevalence of chlamydial infection was 3.2% (confidence limits [CL] = 1.1-5.9) with a prevalence of 2.2% in nonpregnant women and 9.3% in pregnant women. Overall prevalence by the DFA test was 5.45%. Pregnancy status and youth were the significant predictors of risk for infection as determined by culture but not by Microtrak. Payment status, clinical cervicitis, and gonorrhea cultures were not useful predictors of increased risk. I discuss the implications of using culture, an imperfect "gold standard," for determining sensitivity, specificity, and prevalence.

Adolescent↗
PubMedDate not supplied

Tuberculosis screening and prevention for foreign-born students: eight years experience at Ohio University.

In the mid-1980s, international students enrolled at Ohio University were identified as a high-risk group for tuberculosis (TB), contributing an estimated 30%-50% of all active TB cases in the sparsely populated county where the university is located. While the student health center routinely screened all newly enrolled international students with PPD Mantoux tests, no provision for Isoniazid (INH) chemoprophylaxis was available until the Preventive Medicine/Public Health Section of Ohio University College of Osteopathic Medicine initiated a program in September 1985. In 1993, cases of active TB among international students had declined significantly from a pre-1986 rate of 97.5/100,000 student-years to 19.4/100,000 after 1986 (P < .01), while case rates among other groups in the county increased. Positive PPD reaction rates have remained high (53.6%), but less than 15% of international students who should have taken INH chemoprophylaxis by Centers for Disease Control (CDC) criteria did so. This finding suggests that other factors may have contributed to the observed decline in active cases. We examined the influence of five variables (age, gender, geographic origin, BCG vaccination status, and year of enrollment) on PPD status. In this international student population, geographic origin and BCG vaccination status were the most important contributors to positive PPD testing. We suggest that PPD status alone may no longer be sufficient to distinguish those at higher risk of developing active TB in similar populations. A changing mix in international students' geographic origin and BCG vaccination status may help explain the decrease in active case rates in the face of continued high positive PPD rates.

Adult↗