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Biomedical subjects

L Underwood

Publications and source records attributed to L Underwood.

14 recordsLinked to original sources
PubMed1980

Comparative luteolytic effects of prostaglandin F2 alpha and its 13-dehydro analogs in vivo.

Several 13-dehydro analogs were shown to be luteolytic in both the cyclic sheep and cyclic primate models studied. The fact that these luteolytic analogs have diminished uterine smooth muscle activity suggests that the receptors governing the smooth muscle effect on the one hand, and the luteolytic effect on the other, may possess different structural specificities. In both species studied, the analogs showed marked resistance to the PG-15-OH-dehydrogenase in vivo as shown by their activity when infused intravenously. In the early pregnant monkey, the reduced luteolytic activity of the 13-dehydro analogs suggests that mCG may have a protective effect on the corpus luteum to PGs in general. Thus, the early pregnant monkey, or possibly the hCG-treated cyclic monkey, would appear to be "essential" models in the study of luteolytic agents in the primate. Finally, previous reports of termination of early pregnancy in monkeys with luteolytic PG analogs may have depended, at least in part, on their intrinsic smooth muscle activity on the uterus.

Animals↗
PubMed1979

Dacryocystorhinostomy: a modification of the Dupuy-Dutemps operation.

In a series of 112 cases, dacryocystorhinostomy with direct anterior and posterior flap anastomosis has produced a success rate of 94%. Modifications from the original procedure described by Dupuy-Dutemps include preparation of the lacrimal sac flaps and preplacement of the sutures prior to the osteotomy which facilitates accurate identification and approximation with the nasal flaps. Adaptic gauze impregnated with polysporin ointment is packed into the rhinostomy site and out to the anterior nares to maintain patency and minimize clot and membrane formation. Common canalicular stenosis must be recognized and treated with silicone intubation to prevent failure in an otherwise correctable situation.

Adult↗
PubMed1976

Temporal relationship between basal body temperature nadir and luteinizing hormone surge in normal women.

Basal body temperature (BBT) as a predictor of ovulation was assessed by examining the temporal relationship between the BBT shift and the luteinizing hormone (LH) surge in individual cycles of 27 normal women. For 22 of the subjects, the LH surge occurred on the same day or within one day of the BBT nadir. For the remaining five subjects, the surge fell within 2 days after or 3 days before the nadir. Despite the BBT nadir's close temporal association with the LH surge, daily examination of BBT for the purpose of predicting the day of ovulation during a given cycle is unsatisfactory. By 48 hours following the nadir, when one could usually be certain that temperature elevation had occurred, all subjects had already exhibited the LH surge.

Adult↗
PubMed1973

Regulation of adrenal ornithine decarboxylase by adrenocorticotropic hormone and cyclic AMP.

Adrenal ornithine decarboxylase activity was stimulated in a dose-related manner after administration of ACTH or dibutyryl ((6)N-2'-O-dibutyryl) cyclic AMP to hypophysectomized rats. Little effect was observed for 2 h, but striking increases in enzyme activity were observed 4 h after administration of these substances. Effects of ACTH and dibutyryl cyclic AMP were not secondary to stimulation of steroidogenesis, since hydrocortisone had no effect on adrenal ornithine decarboxylase although it did stimulate activity of the enzyme in the liver and kidney.ACTH, given subcutaneously to hypophysectomized rats, induced striking increases in adrenal cyclic AMP levels within 15-30 min with a fall towards the base line in 1 h. Increases in ornithine decarboxylase activity lag several hours after this endogenous cyclic AMP peak, in contrast to the stimulatin of steroidogenesis by the nucleotide that requires only 2-3 min. After graded doses of ACTH, increases in adrenal cyclic AMP levels at 30 min were paralleled by proportional increases in adrenal ornithine decarboxylase activity 4 h after hormone treatment. Whereas maximal levels of adrenal steroidogenesis have been observed at tissue cyclic AMP levels of 6 nmol/g. ACTH is capable of inducing increases in nucleotide levels up to 200 nmol/g or more. These high tissue levels of cyclic AMP, although unneccessary for maximal steroidogenesis, appear to stimulate adrenal ornithine decarboxylase activity. Several results in addition to the time lag in the stimulation of ornithine decarboxylase activity suggest a mechanism involving accumulation of the enzyme or some factor needed for its activity rather than direct activation of the enzyme by cyclic AMP. Thus, the addition of cyclic AMP directly to the ornithine decarboxylase assay mixture in vitro was without stimulatory effect. In addition, actinomycin D or cycloheximide in doses sufficient to block adrenal RNA and protein synthesis, respectively inhibited the stimulation of ornithine decarboxylase activity by ACTH in vivo. An adrenocortical cancer was found to maintain ornithine decarboxylase activity at very high levels, but did so at much lower cyclic AMP levels than those of ACTH-stimulated adrenals. It is concluded that ACTH stimulates adrenal ornithine decarboxylase activity and that this effect may be mediated by cyclic AMP. However, cyclic AMP be mediated by appear to be a determinant of the high level of enzyme activity found in adrenocortical cancer.

Adrenal Gland Neoplasms↗