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Biomedical subjects

R Page

Publications and source records attributed to R Page.

At least 91 records · Page 5Linked to original sources
PubMed1983

Simultaneous bilateral venous sampling for adrenocorticotropin in pituitary-dependent cushing's disease: evidence for lateralization of pituitary venous drainage.

At present it is not established whether lateralization of pituitary venous drainage occurs in humans. To explore this possibility, we performed bilateral simultaneous inferior petrosal sinus sampling for ACTH in three patients with surgically proven ACTH-secreting pituitary microadenomas laterally located in the pituitary gland. In each patient, a gradient for ACTH correctly identified the location of the tumor. This finding suggests that pituitary venous drainage in humans is lateralized. These data also demonstrate that inferior petrosal sinus sampling needs to be bilateral before the pituitary origin of ACTH hypersecretion can be safely excluded in patients with Cushing's syndrome. In at least one and possibly two patients, the pituitary origin of ACTH excess would have been missed had we only sampled one inferior petrosal sinus. Finally, the demonstration of a left to right central gradient for PRL in addition to ACTH in one patient suggests that this technique may be useful in lateralizing functioning pituitary tumors other than ACTH-secreting tumors.

Adenoma↗
PubMed1981

Pituitary hollow fiber units in vivo and in vitro.

A new technique is described for the study of mammalian pituitary cells in vivo and in vitro. The method involves encapsulation of freshly trypsinized rat, sheep or human pituitary cells in XM-50 Amicon hollow fibers followed by their intracranial implantation into hypophysectomized rats. These pituitary fiber units promoted recipient growth for 3 weeks before weight gains plateaued. Body composition analyses showed that significant quantities of protein, fat and ash accounted for the weight gain. Morphological study of the capsule contents 7-39 days postimplantation revealed the presence of intact somatotrophs and corticotrophs. The hollow fibers may provide an immunologically privileged site by virtue of the fact that the 50,000 dalton pores making up the lumen surface permit pituitary hormones to diffuse from the capsule, but theoretically do not permit immunoglobulin molecules to penetrate the capsule. Growth of hypox rats receiving capsules containing allogeneic rat pituitary cells, sheep cells or pieces of human postmortem pituitary support this concept. Furthermore, rats implanted with human PRL adenoma cells had detectable quantities of circulating hPRL 100 days postimplantation. It is suggested that the pituitary hollow fiber units function when they come in contact with a ventricular surface of a hypox animal. With these units, it will be possible to study function of the same group of pituitary cells in vitro and in vivo.

Acrylic Resins↗
PubMed1981

Pituitary cell transplants to the cerebral ventricle suppress the pituitary of the recipient host.

Implantation of 1 x 10(6) acutely dispersed rat pituitary cells into the lateral ventricles of sexually immature and mature female rats of both the Sprague-Dawley and Fisher strains significantly suppressed the weight and protein content of the in situ pituitary 12 days postimplantation. Body weight gains in the young animals were also significantly lower. Changes in the in situ pituitary of the cell implanted groups were demonstrated by repeatable reductions (approximately 50%) in total pituitary GH and PRL content. Total pituitary TSH, FSH and LH were usually unaffected. Although the mechanism of cell-mediated suppression of the host pituitary is unknown, the approach should be of use in future studies of feedback regulation on pituitary gland function.

Animals↗
PubMed1980

Age and you.

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Accounting↗
PubMed1977

Hypothalamic hamartoma: a source of luteinizing-hormone-releasing factor in precocious puberty.

The presence of a hypothalamic hamartoma and precocious puberty in a 19-month-old boy provided an opportunity to study their relation. Excised tissue had the ultrastructural characteristics of an independent neuroendocrine unit -- i.e., neurons containing neurosecretory granules and blood vessels with fenestrated endothelium and double basement membranes. Immunofluorescence studies using specific antibody to luteinizing-hormone-releasing factor showed antigenicity to the factor in the hamartoma. The testicular-hypothalamic-pituitary axis was tested. Clomiphene unresponsiveness suggested a lack of maturation of central-nervous-system events characteristic of normal puberty. The negative feedback system between gonad and brain was intact but partially resistant to steroid suppression. These studies suggest that hypothalamic hamartomas may cause precocious puberty by autonomous production and release of luteinizing-hormone-releasing factor into vessels that communicate with the pituitary portal blood system.

Brain Neoplasms↗
PubMed1977

Mitogenic activity of Actinomyces viscosus. I. Effects on murine B and T lymphocytes, and partial characterization.

Actinomyces viscosus homogenate (AVIS) contins substance(s) which cause spleen cells from conventional and germfree mice to undergo increased DNA synthesis. This mitogenic effect is primarily on B cells since spleen cells from nude mice or T-depleted spleen cells from conventional mice respond as strongly as conventional (T + B) spleen cells. Mouse thymocytes do not respond mitogenically to AVIS. It is unlikely that the mitogenic acitivity is due to the presence of LPS, since A. viscosus is Gram-positive and is not known to have an LPS cell wall component. Also, AVIS is not inactivated by polymyxin B, as are some preparations of LPS, and C3H/HeJ mouse splenocytes respond strongly to AVIS but not to LPS. The activity is heat stable, is not lost upon dialysis, and is not affected by lysozyme. Mitogenic activity is partially lost when AVIS is digested with nonspecific bacterial protease or treated with metaperiodate. Sodium hydroxide treatment completely abolishes mitogenic activity. Actinomycotic lesions are characterized by a long-tern inflammatory response involving a dense plasma cell infiltrate. We suggest that B cell mitogens form Actinomyces may play a role in the elicitation of the plasma cell component of these lesions.

Actinomyces↗
PubMed1975

Sexual activity and contraception use in young adults.

241 (57 male and 184 female), well-educated, largely urban, young persons, voluntarily attended a lecture on sex; after the lecture they completed an anonymous questionnaire on their background, and attitudes to sex. A majority believed that premarital sexual activity was acceptable if there was some affectional tie between the couple. Most of the men were sexually active, while only a third of the women were so. However, a quarter of the sexually inexperienced men and women were engaging in forms of sexual stimulation which would seem to carry a high possibility of ending in intercourse. Knowledge of contraception, while high, tended to over-estimate the efficacy of the safe period and vaginal methods. Half the sexually active group had used contraception at sexual initiation but only a third had used reliable methods. Subsequent contraceptive practice however, was high (90 percent), with the pill being the most frequently used method. Twenty percent of the sexually active women had already been pregnant: of these only a quarter had carried their pregnancies to term. The limitations of the study are discussed and some suggestions for preventing pregnancy in the unmarried drawn.

Adolescent↗