Showing papers by "Michael J. Baum published in 1985"

Coital stimuli controlling luteinizing hormone secretion and ovulation in the female ferret.

Abstract: A series of experiments focused on the masculine coital behaviors controlling pituitary luteinizing hormone (LH) secretion and reflex ovulation in the estrous female ferret. An initial experiment investigated which coital stimuli from the male are required to induce ovulation. It was found that corpus luteum formation, which served as an index of ovulation, occurred in estrous female ferrets only if the male achieved a penile intromission. Neck gripping, mounting, and pelvic thrusting behavior without intromission by the male failed to induce ovulation. A second experiment investigated the timing and magnitude of the coitus-induced LH surge associated with ovulation. Blood was obtained via jugular catheters from estrous females in various mating situations. Plasma LH concentrations were measured by a heterologous radioimmunoassay that was validated for use in the ferret. A significant surge in plasma LH occurred only when an intromission was achieved by the stud male. Plasma LH was significantly elevated 2.0 h after the introduction of the male, peak values were reached 6.0 h later, and this elevation lasted on average 5.7 hours (5/5 females). No LH rise occurred in 2/2 female ferrets in which only neck gripping, mounting, and pelvic thrusting, but no intromission, were allowed to occur. The ferret mating pattern and the resultant LH response differ from those seen in three other induced ovulators (cat, vole, and rabbit) in which the male's intromission latency and duration are much shorter than in the ferret, and in which a distinctive peak in plasma LH often occurs within 1 h after mating.

Androgen Aromatization and 5α-Reduction in Ferret Brain during Perinatal Development: Effects of Sex and Testosterone Manipulation*

Abstract: Ferrets of both sexes were killed 8 or 5 days before expected parturition as well as 7, 15, 30, or 51 days after birth, and the activities of aromatase (using 19-[3H]hydroxyandrostenedione as substrate) and of 5α-reductase (using [3H] testosterone as substrate) were assayed in whole homogenates of preoptic area plus anterior hypothalamus (POA), mediobasal hypothalamus (MBH), temporal lobe (TL), and cerebral cortex. Aromatase and testosterone 5a-reductase activities were also measured in these regions in adult gonadectomized male and female ferrets. Compared with adults of both sexes in which aromatase activity was low in all brain regions studied, fetal ferrets had high levels of aromatase activity in POA plus MBH and in TL. At these prenatal ages, aromatase activity in POA plus MBH was significantly higher in males than in females. Aromatase activity in POA, MBH, and TL remained high in both sexes on postnatal days 7, 15, and 30, before declining by postnatal day 51. Cortical aromatase activity was unifo...

Androgen and estrogen receptors in perinatal ferret brain

Abstract: Using DNA-cellulose affinity chromatography and either 3H-labeled dihydrotestosterone, testosterone, or estradiol, we qualitatively and quantitatively analyzed the androgen- and estrogen-binding activities present in four regions of male and female ferret brain at prenatal, early and late neonatal, and adult ages. The cytosolic androgen- and estrogen-binding activities in ferret brain at all ages studied were qualitatively similar in both sexes and in all brain regions and exhibited characteristics which resemble those of androgen and estrogen receptors from other species, including rodents and nonhuman primates. A developmental analysis indicated that high levels of both androgen and estrogen receptors were present in the hypothalamus-preoptic area as early as 5 days before birth. A significant, transient decline in concentrations of estrogen receptors (approximately 5-fold) occurred in anterior hypothalamus-preoptic area and mediobasal hypothalamus at 12 days of age in both males and females; this phenomenon has not been observed in any other species studied to date. The observed ontogeny of androgen receptors correlates with the known ability of testosterone, acting over postnatal days 5 to 20, to cause coital masculinization in ferrets, whereas the observed postnatal dip in estradiol receptor concentrations correlates with the inability of estradiol to cause coital masculinization or defeminization of receptive behavior in this species.

Evidence of proceptive without receptive defeminization in male ferrets.

Abstract: The latencies of groups of gonadectomized male and female ferrets to approach and interact with a sexually active stimulus male were measured after administration of estradiol benzoate (EB; 0, 5, 10, or 15 micrograms/kg) in adulthood. Receptive responsiveness to stud males was also assessed in these same ferrets during additional tests. Control female ferrets gonadectomized on Postnatal Day 35 displayed a dose-dependent reduction in approach latencies to the stud male which did not occur in control males castrated on Day 35. The approach latencies of males castrated on Postnatal Day 20 or Day 5 were intermediate between these two extremes. Equivalent dose-dependent reductions in approach latencies were observed in groups of ferrets ovariectomized on Day 5 and implanted sc with Silastic capsules containing either no hormone or different doses of testosterone over Postnatal Days 5-20 or 20-35. Equivalent dose-dependent increments in acceptance quotients were obtained in all groups of male and female ferrets following EB treatment. These results suggest that the capacity to display the proceptive, or appetitive, components of feminine sexual behavior is normally reduced in male ferrets as a consequence of the perinatal action of testicular hormones whereas receptive behavioral capacity is retained in males of this species.

Inhibition of mating by naloxone or morphine in recently castrated, but not intact male rats.

Abstract: Administration of naloxone (SC 5 mg/kg) significantly reduced ejaculation and mounting in male rats in the weeks following castration. A similar effect was obtained by injecting morphine (SC 1 or 5 mg/kg). In contrast, the same dosages of naloxone or morphine did not affect the sexual performance of gonadally intact males. Opioid peptides may contribute to the temporary persistence of sexual behavior in testosterone-deficient male mammals, in which incentive qualities of the female partner are an important determinant of sexual arousal.

Six-year results of a controlled trial of tamoxifen as single adjuvant agent in management of early breast cancer

Abstract: A randomized controlled trial of tamoxifen as a single adjuvant agent after mastectomy for early breast cancer, reported on at an average follow-up of almost 2 years in 1983, has now been followed up to a maximum of 6 years. One thousand two hundred eighty five patients aged 75 or less were entered into the trial. Premenopausal women with positive axillary nodes and postmenopausal women with both positive and negative axillary nodes were randomized to receive either tamoxifen 10 mg twice daily for 2 years or to the untreated control group with systemic therapy reserved until the time of relapse. Forty-six percent of the trial population had primary tumor specimens assayed for estrogen receptor (ER) content. There has been a highly significant reduction in death rate, with 45 (34%) fewer deaths observed in the treated group than in the control group. This benefit appeared to be independent of menopausal, nodal, or ER status.

Endocrine Control of Behavioural Sexual Differentiation in the Male Ferret

Abstract: Over the past 25 years much evidence has accumulated (reviewed in Baum 1979) to show that sexual dimorphisms in mammalian social behaviour ultimately derive from dimorphic patterns of sex steroid hormone secretion and brain action during critical perinatal periods of development. It is well established that a primary source (in the view of many investigators, the only source) of this perinatal sex difference in steroidal environment results from the presence of testes in the male. Over the past 13 years we have explored the contribution of testicular secretions to the process of brain and behavioural sexual differentiation in the male ferret (Mustek furo), a carnivorous mammal in which gestation lasts approx. 42 days. The results of an initial experiment (Baum 1976) showed that prenatal administration of testosterone propionate (TP) to female ferrets caused extensive masculinization of the external genital organs, whereas this treatment had no effect on the females’ ability to display either feminine or masculine coital behaviour in adulthood, following gonadectomy and concurrent treatment with either oestradiol benzoate (OB) or TP. By contrast, females which received TP over the first 10 postnatal days of life later displayed high levels of masculine coital behaviour, when tested with concurrent OB or TP stimulation. These findings focussed our attention on the late gestational and early postnatal ages of development as potentially important periods for the process of brain sexual differentiation in ferrets.

The Stress of Breast Cancer

Abstract: A diagnosis of breast cancer is critical in its physical implications, and it is also a crisis for the patient at an emotional level. Ervin (1973) has remarked that “there are few physical conditions which threaten a woman on so many fronts simultaneously” (1973, p. 42). Anxiety, depression, and anger may be triggered by the images that the term cancer evokes while, at the same time, the removal of the breast and any other treatment will create additional strains. The multifaceted threat is one that unfolds over time, from the first discovery of the breast lump, and the woman’s experience at any one stage is colored by what has gone before and her reactions to this. The diagnosis of cancer has a different impact on the woman who strongly anticipated this eventuality than on one for whom it seemed a remote possibility; and the final adaptation to the illness and to the mastectomy in later years depends on the woman’s earlier reactions and the ways of adapting she chose at that time. In this chapter we consider first the patients’ adjustment following mastectomy, with a subsequent discussion of the specific threats and conflicts associated with a diagnosis of cancer and with the loss of the breast. Evidence relating to the psychological impact of lumpectomy is scant, and is referred to in that section. Finally, we address the effects of radiotherapy and systemic therapy.

Two cheers for the computer

Abstract: I Peters W. New answers through chemotherapy? Expenrentia 1984;40: 1351-7. 2 Petrs W. Antimalarial drug resistance: an increasing problem. Br MedBull 1982;38:187-92. 3 British Medical Association and Pharmaceutical Societs of Great Britain. Brtish nationalformularm. Number 9. London: British Medical Association and Pharmaceutical Society of Great Britain, 1985. 4 Association of British Pharmaceutical Industry. Data sheet Compendium 1985-1986. London: Datapharm Publications, 1985 :622.