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Biomedical subjects

T J Collins

Publications and source records attributed to T J Collins.

115 records · Page 7Linked to original sources
PubMed1980

Plasma and pituitary concentrations of LH, FSH and prolactin in aged female C57BL/6 mice.

Plasma and pituitary concentrations of LH, FSH and prolactin were determined by radioimmunoassay in 2-month-old (young) and 16-20-month-old (old) C56BL/6 mice. There were no statistical differences in hormonal levels between aged females in oestrus (those exhibiting a copulatory plug) and those in constant dioestrus. In the old females plasma levels of LH (P < 0.002) and FSH (P < 0.001) were significantly elevated, while levels of prolactin (P < 0.001) were significantly depressed when compared with those from young animals. Pituitary homogenates from old females also contained more gonadotrophins (P < 0.001) and less prolactin (P < 0.001) than those of the young females. A radioreceptor assay utilizing a plasma membrane of luteinized rat or mouse ovaries indicated that LH from 2-month-old animals bound better to ovarian receptors (P < 0.05) than did LH from old mice, although radioimmunoassay of the same samples gave higher (P < 0.01) plasma LH levels for the old mice. Since the radioreceptor assay is considered to be a more sensitive test for biologically active LH, the results from these two types of assays suggest that there may be an alteration in the mouse LH molecule with age.

Aging↗
PubMedDate not supplied

Characterization of a potent biotin-conjugated CRF analog and the response of anterior pituitary corticotropes.

A biotin-conjugated synthetic corticotropin releasing factor (B-CRF) was prepared and characterized. Its biological activity and binding affinity were compared with that of unlabeled synthetic CRF. Both forms of the releasing factor were equipotent in in vitro studies measuring the release of corticotropin (ACTH) (ED50 = 1 nM). The IC50 in the binding assays was 1.5 nM for CRF and 4 nM for B-CRF. Dual avidin-biotin peroxidase complex stains were then used in pituitary monolayer cultures to visualize receptivity to the releasing factor and to confirm opiocortin storage in the target cells. All corticotropes showed stain for B-CRF. The percentage of cells that were double-labeled for ACTH and CRF increased with the dose of B-CRF during a four hour incubation period. The CRF stain was abolished, however, when an excess of unlabeled CRF was added to compete with B-CRF. The distribution of the B-CRF and ACTH stains varied in the cells with the time of exposure to the analog. These studies show that biotin-conjugate CRF is a potent analog that can be demonstrated cytochemically on cells identified immunocytochemically as corticotropes. It can be used to follow important events associated with CRF stimulation including the rapid internalization of CRF coupled with the mobilization of corticotropin stores and the formation of cellular processes.

Adrenocorticotropic Hormone↗
PubMedDate not supplied

Directional coronary atherectomy in heart transplant recipients.

Cardiac allograft vasculopathy is one of the most common obstacles to the long-term survival of heart transplant recipients. Percutaneous transluminal angioplasty has been used as a palliative treatment for discrete lesions caused by this disease, but it is often complicated by restenosis. This report describes two cases in which directional coronary atherectomy was used to treat the discrete lesions and explores the possible advantages of this intervention in lieu of the traditional approach. Our results suggest that directional coronary atherectomy is a feasible alternative to conventional balloon angioplasty.

Atherectomy, Coronary↗