Three different karyotypes have been found SO far among Saimiri originating from five different South American localities. All animals examined have the same diploid number (44) of chromosomes but the number of acrocentric and submetacentric chromosomes varies, presumably as a result of pericentric inversions. Saimiri originating from Iquitos, Peru, consistently have ten acrocentric chromosomes; animals originating from Leticia, Colombia, have 12 acrocentric chromosomes. Hybrids produced in our laboratory have the expected 11 acrocentrics and one unpaired submetacentric chromosome. Animals originating from Guyana have fourteen acrocentric chromosomes and the expected two fewer submetacentric chromosomes. Squirrel monkeys from Costa Rica, Panama, and Pucallpa, Peru, studied to this date conform to the Iquitos type with ten acrocentric chromosomes. These findings point to genetic differences which may result in variable responses to laboratory situations. The evolutionary factors involved in this rearrangement of chromosomes and possible influences on phenotypes are subjects of interest for future study. The importance of identifying the source of squirrel monkeys used in biomedical research is apparent if results from different laboratories are to be repeated or compared.

We have examined the direct effects of progestins, oestrogens, peptide hormones and growth factors on oestradiol-17 beta dehydrogenase (OE2DH) activity of cultures of the human breast cancer cell line MCF-7. Cells were cultured in the presence of steroid or peptide for 6 days, after which the number of cells was determined and cellular OE2DH activity assessed. Progesterone, 6 alpha-methyl-17 alpha-hydroxyprogesterone acetate, norethisterone and D(-)-norgestrel all profoundly inhibited cell mitosis and stimulated reductive (oestrone----oestradiol-17 beta) and oxidative (oestradiol-17 beta----oestrone) OE2DH activity. Both oestrone and oestradiol-17 beta directly stimulated reductive OE2DH activity, but had no effect on the oxidative direction. Oestradiol-17 beta stimulated cell growth only in phenol-red free culture medium. Ovine prolactin, LH, epidermal growth factor and transforming growth factor did not alter OE2DH activity but small stimulatory effects on the growth of MCF-7 cells were exerted by prolactin and a combination of transforming growth factor with epidermal growth factor. It is concluded that these results may explain, at least in part, the alterations in mitotic activity and tissue oestradiol-17 beta levels observed in breast tissue during varying physiological and pathological conditions, such as during the menstrual cycle and in breast cancers.

BACKGROUND: The number of organs available for transplantation in the United States is insufficient, and the donor rate in New Jersey is particularly low. OBJECTIVES: To explore reasons nurses do or do not refer organ donors and to identify factors that contribute to differences in referral rates in New Jersey and Pennsylvania. METHODS: Registered nurses (N = 976) in 57 nongovernmental acute care hospitals, primarily in emergency departments and intensive care units, completed a questionnaire that focused on their knowledge and participation in the organ procurement process. RESULTS: Two-thirds of the subjects said they had participated in organ procurement. Pennsylvania nurses had a significantly higher involvement rate than New Jersey nurses. Pennsylvania nurses were also slightly more knowledgeable about the process. A higher proportion of nurses in both states who attended continuing education programs participated. CONCLUSIONS: Nurses need more inservice education regarding policies and procedures for organ donation.

1 The mechanism of the antihypertensive effect of ot-methyldopa was compared with clonidine by administering equipotent single doses of clonidine (0.2 mg) and amethyldopa (750 mg) to nine hypertensive patients. Plasma noradrenaline was followed for 8 h thereafter as an index of peripheral sympathetic activity. 2 a-Methyldopa and clonidine produced the same hypotensive response at 6 and 8 h after dosing with a similar fall in plasma noradrenaline levels at these times. 3 Linear regression analysis between the systolic blood pressure fall and the corresponding plasma noradrenaline fall, showed that the slopes of the two regression lines were similar for a-methyldopa as for clonidine. 4 Equipotent doses of ao-methyldopa and clonidine produce the same fall in plasma noradrenaline. This supports the current hypothesis that an a-methyldopa metabolite acts centrally, like clonidine, to reduce peripheral sympathetic activity.

SynopsisUptake of oestrogens into breast tissue and their subsequent metabolism can be studied by infusing radio-labelled steroids into volunteer patients. Such studies show that oestradiol is preferentially accumulated in breast tumours, oestradiol concentrations exceeding those of oestrone. This contrasts with plasma, in which oestrone concentrations in postmenopausal women are greater than those of the oestradiol. This observation suggests that tissue factors can modulate local oestrogen metabolism, and thus local steroid concentrations.We have studied the local production of oestrogens from androgen, and also the interconversion of the major oestrogens, oestrone and oestradiol. Using isotopic techniques, it is possible to calculate the proportion of endogenous oestrogen produced from androgen, as opposed to uptake from the circulation. These studies suggest that a very variable proportion of tissue oestrogen derives from endogenous synthesis. After administration of aromatase inhibitors, aromatase activity is substantially inhibited, both in vivo and in vitro.Relative oestrogen concentrations are determined in part by the activity of oestradiol dehydrogenase. In breast tissue, dehydrogenase activity is present and this is modified by various factors, including androgens. In addition, we have demonstrated that normal, benign and malignant breast tissues produce factors which can modulate both growth and dehydrogenase activity of cancer cells in vitro.We conclude that breast tissue is a site of synthesis of oestrogens, and that a number of factors can affect their local concentration. Tumour cells produce growth factors which can influence steroid metabolism, and may thus be able to enhance favourably their own endocrine environment.