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Biomedical subjects

J F Jarrell

Publications and source records attributed to J F Jarrell.

26 records · Page 2Linked to original sources
PubMed1985

Does dihydrotestosterone induce atresia in the hypophysectomized immature female rat treated with pregnant mare's serum gonadotropin?

This study was originally designed to test the hypothesis that the binding of luteinizing hormone in granulosa cells decreases with atresia. The hypophysectomized immature female rat that was primed with pregnant mare's serum gonadotropin and treated with dihydrotestosterone was used as a model for atresia. Histochemical analysis of acid phosphatase was used as a marker for atresia and topical autoradiography with iodine 125-labeled human chorionic gonadotropin for binding of luteinizing hormone. Histologically, there was no significant difference in atresia, acid phosphatase, or 125I-labeled human chorionic gonadotropin binding in antral follicles between control animals given pregnant mare's serum gonadotropin and animals treated with pregnant mare's serum gonadotropin and dihydrotestosterone. Assessment of the total follicular population, however, showed that dihydrotestosterone at dosages of 1 and 5 mg/kg resulted in decreases in atresia of 48% and 58%, respectively. Although these data disprove our hypothesis, they strongly suggest that dihydrotestosterone decreases follicular atresia by increasing the number of small preantral follicles.

Acid Phosphatase↗
PubMed1984

Delayed hemorrhage following conservative surgery for tubal ectopic pregnancy: prevention and early detection.

There is growing acceptance of conservative surgery for ectopic (tubal) pregnancy. An uncommon, yet potentially fatal, complication is delayed hemorrhage due to persistence of gestational tissue. An illustrative case is presented. Routine postoperative determination of serum human chorionic gonadotropin levels and the use of frozen sections when a partial salpingectomy is carried out are recommended to identify and prevent this condition.

Adult↗
PubMed1983

Release of 3H2O from 1 beta,2 beta[3H]androstenedione by equine granulosa cells.

Granulosa cells were harvested from mares at various stages of the oestrous cycle and incubated in Krebs-Ringer bicarbonate buffer with 1 beta,2 beta[3H]androstenedione as substrate. The release of 3H2O expressed as CPM/h/mg protein varied from 44000 to 768000 in follicles from 7 mares. The release of 3H2O was not significantly altered by luteinizing hormone, follicle stimulating hormone or pregnant mare's serum gonadotrophin. There was a significant negative correlation between the release of 3H2O and the concentration of progesterone in the follicular fluid. Based on the assumption that the release of 3H2O represent total aromatization, these data suggest that the equine granulosa cells have a very active aromatizing enzyme system.

Androstenedione↗
PubMedDate not supplied

Alterations in circulating ovarian steroids in hexachlorobenzene-exposed monkeys.

Hexachlorobenzene (HCB) is a global pollutant that has been identified in human serum and ovarian follicular fluid, and its effect on ovarian function has not been adequately defined. Thus, the effects of HCB on ovarian steroidogenesis and menstrual cycle characteristics were investigated in cynomolgus monkeys (n = 16) orally dosed by gelatin capsule (0.0, 0.1, 1.0, and 10.0 mg HCB/kg b.wt./d) for 90 d (approximately three menstrual cycles). Analysis of change in menstrual cycle length for each animal revealed a dose-dependent increase (P = 0.02) in cycle length. Ovulatory levels of estradiol (E2) were significantly reduced (P = 0.02) in the highest treatment group. During ovulation induction, the area under the E2 concentration curve (AUC) was significantly (P = 0.03) suppressed in the highest treatment group. Our data demonstrate that HCB treatment, under the conditions of the present study, alters both ovarian function and menstrual cycle characteristics with a no observable adverse effect level of 1.0 mg/kg.

Animals↗
PubMedDate not supplied

Hexachlorobenzene exposure and the proportion of male births in Turkey 1935-1990.

Hexachlorobenzene (C(6)Cl(6), HCB) is a chemical that has been associated with significant immediate and long term adverse health effects in humans. It has been associated with both porphyria cutanea tarda and spontaneous abortions among survivors of widespread exposure in the 1950s in southeastern Turkey. HCB binds to the Ah receptor, albeit with lower affinity than dioxin. Dioxin exposure has been reported to lower human secondary sex ratio, putatively through a male mediated effect. We therefore wished to evaluate the impact of the HCB environmental event on the sex ratio of the progeny of the survivors. We undertook an assessment of 1) the effects of HCB exposure on the proportion of male births of individual subjects who had survived, 2) variables that significantly predicted the proportion of males among these individuals, and 3) the trend of the population sex ratio born in Turkey from 1935 to 1990. Women known to have been exposed to HCB in the 1950s did not have offspring with a significantly different sex ratio when compared to control populations. However, subjects reporting exposure at the peak of the episode (1955-57) had a significantly lower lifetime proportion of males than those exposed at a later date. The lifetime reported spontaneous abortion rate of these women also significantly predicted the percent males per subject. The available national data demonstrated a significant reduction in the calculated proportion of males from 1935 to 1970 that stabilized from 1970 to 1990. These data indicate that HCB exposure that was sufficient to induce clinical porphyria cutanea tarda may also have reduced the proportion of males in subjects over their reproductive life-span. The HCB episode does not explain the pattern of the national trend from a population perspective.

Abortion, Spontaneous↗
PubMedDate not supplied

The effect of photomirex on the in vitro perfused ovary of the rat.

Photomirex, a photodegradation product of the insecticide mirex, is an environmental contaminant that has been identified in Great Lakes fish, soil, and human adipose tissue. Because of the potential for human exposure, the present study was designed to investigate the short-term effects of photomirex on the in vitro perfused ovary of the rat. Adult Sprague-Dawley rat ovaries were isolated and perfused for a total of 6 h with Medium 199. Following a 2-h baseline period, 10(-4) M of photomirex was administered to the medium. Control ovaries received medium or DMSO (vehicle control). Significant effects of perfusion and chemical intervention were identified using lactate dehydrogenase enzyme, glucose utilization, lactate, pyruvate, and flow:pressure ratio as markers of toxicity (P < 0.05). Lactate:pyruvate ratio, glutathione, and oxygen consumption did not demonstrate significant effects. Post hoc tests showed that there were significant differences between the DMSO + photomirex group and the control group (M199) using lactate dehydrogenase as a marker of toxicity. Pyruvate concentration was also reduced significantly after perfusion with DMSO + photomirex compared to M199 only and DMSO only (P < 0.05). Histopathologic changes were not discernible by light microscopy. These results suggest that metabolic and respiratory processes of the ovary are acutely sensitive to perturbation with photomirex in the in vitro perfused rat ovary model.

Animals↗
PubMedDate not supplied

Developmental changes in the gonadotropin releasing hormone neuron of the female rabbit: effects of tamoxifen citrate and pregnant mare serum gonadotropin.

Developmental changes in immunostained gonadotropin releasing hormone neurons were demonstrated in female rabbits assigned to the following treatment groups: (i) tamoxifen citrate, 10 mg.kg-1 x day-1, in sesame seed oil (vehicle) (n = 24) or (ii) vehicle alone (control, n = 24) for 108 days; and (iii) 50 IU of pregnant mare serum gonadotropin on postnatal days 22 and 25 (n = 24) or vehicle on nontreatment days. Treatments had no effect on the total number of immunostained cells, but there was a significant (p = 0.0160) developmental shift from cells with smooth processes to rough. Group comparisons revealed that there was a significant (p < 0.001) age-related increase in the number of rough cells in pregnant mare serum treated rabbits between days 25 and 75, indicating an advancement in the shift from smooth to rough cells. Plasma gonadotropin levels, ovarian follicular development, and the developmental shift from smooth to rough cells were markedly suppressed by tamoxifen treatment compared with rabbits of the control group, while no difference in estradiol levels were found. Our results suggest that a developmental shift in gonadotropin releasing hormone cell morphology from smooth to rough precedes sexual maturity in the female rabbit.

Animals↗