Biomedical subjects
R F Williams
Publications and source records attributed to R F Williams.
Hyperprolactinemia in monkeys: induction by an estrogen-progesterone synergy.
To evaluate the synergistic effect of estrogens and progesterone on prolactin secretion, rhesus and cynomolgus monkeys in the early follicular phase received estradiol benzoate (100 microgram/kg/day, sc) alone for 14 days, then in combination with progesterone (subcutaneous silastic capsule) for an additional 14 days. Blood was drawn daily by femoral venipuncture under ketamine hydrochloride anesthesia (15 mg/kg). Similarly, this protocol for exogenous steroid treatment was employed in a monkey having a chronically indwelling (femoral insertion into the vena cava) cannula maintained by a vest and mobile tether apparatus; however, no anesthesia was used to obtain serum specimens. In addition, this assembly was applied to six monkeys to determine the acute effects of ketamine hydrochloride on prolactin secretion. Concentrations of prolactin, estradiol-17 beta, and progesterone in serum were determined by conventional radioimmunoassays. Under estrogen therapy alone, mean circulating prolactin levels declined from approximately 15 to less than 5 ng/ml; in contrast, the addition of progesterone caused an abrupt serum prolactin elevation, approximately 8-12 fold. This estradiol-progesterone course led to sustained hyperprolactinemia in the chronically catheterized monkey, whereas ketamine administration raised serum prolactin only briefly, the elevation lasting less than three hours after injection. These findings establish that an estrogen-progesterone synergy, separate from the transient effects of ketamine, induced hyperprolactinemia in cycling monkeys having prevailing levels of estrogen and progesterone near those characteristic of late gestation, when sustained prolactin elevations are observed normally.
Pulsatile pituitary gonadotropin secretion during maturation of the dominant follicle in monkeys: estrogen positive feedback enhances the biological activity of LH.
In the follicular phase of the menstrual cycle, pulsatile patterns of LH and FSH secretion in monkeys change during maturation of the dominant follicle. At the preovulatory surge, the most striking event is the prodigious elevations of bioassayable LH, rising up to 50-fold within 24 h. Principally, establishment of the surge is due to marked enhancement of the amplitude of LH secretory pulses. In contrast, LH and FSH measured by RIA enter, in parallel, the surge modes of secretion approximately 5 h later than bioassayable LH and rise more slowly; the B:I ratio may reach 10:1. This same disparity between bioassayable versus immunoassayable LH was induced in castrate monkeys under estrogen positive feedback stimulation. We conclude that the preovulatory estrogen surge promotes the secretion of an LH molecule(s) having enhanced biological activity.
Infection of the respiratory tract and lungs in cystic fibrosis.
Explore the source record for details and available documents.
Rapid recovery of estrogen-induced pituitary gonadotropin surges after luteectomy in rhesus monkeys.
In the presence of a functional corpus luteum, positive estrogen feedback on the surge modes of gonadotropin secretion is blocked in rhesus monkeys. We investigated the effects of luteectomy (Lx) on the time required for recovery of pituitary responsiveness (LH/FSH surges) to positive estrogen feedback. Estradiol-17 beta-3- benzoate (EB, 50 microgram/kg sc) was given: 1) 24th prior to, 2) the day of, or 3) 24 h after luteal ablation. Daily measurements of serum follicle stimulating hormone (FSH), luteinizing hormone (LH), estradiol-17 beta (e2) and progesterone (P) were made on each monkey for 5 days. Serum P fell to undetectable levels within 24 h after Lx, whereas E2 levels in circulation peaked within 24h after injection of EB. Among early follicular phase monkeys, this EB treatment results in typical midcycle type LH/FSH surges within 48h. Lx alone was not soon followed by significant changes in pituitary gonadotropin secretion. When circulating P levels were undetectable the pituitary responded fully to EB; that is, typical midcycle type FSH/LH surges occurred. When serum P was in the midst of declining after Lx, gonadotropin surges were present, but attenuated. However, when P levels remained elevated for more than 24 h after EB injection, the surge modes of FSH/LH secretion remained fully blocked. These results demonstrate that the suppressive influence of luteal secretions (principally progesterone) on positive estrogen feedback regulation of the surge modes of pituitary gonadotropin secretion is quite transient in these primates.
Disparate effects of human chorionic gonadotropin during the late follicular phase in monkeys: normal ovulation, follicular atresia, ovarian acyclicity, and hypersecretion of follicle-stimulating hormone.
Explore the source record for details and available documents.
Reinitiation of the diurnal rhythm of prolactin secretion in postpartum rhesus monkeys.
Explore the source record for details and available documents.
Physicochemical and serological characterization of two rhabdoviruses isolated from eels.
Explore the source record for details and available documents.
The problems, diagnosis and treatment of infection by Staphylococcus aureus.
Present-day problems of infection by Staphylococcus aureus are described against a brief historical account of the evolution of the multiple antibiotic resistant 'hospital staph'. which caused such immense problems of hospital cross-infection in the 1950's and 1960's. These problems have lessened considerably since that time, but staphylococcal infection still remains as a cause of morbidity and mortality. Diagnosis and treatment are not always straight-forward. Apart from applying general supportive measures, and appropriate surgical intervention when necessary, the attending doctor is faced with making a choice from a multiplicity of antibiotic agents. A brief account of the main antibiotic agents currently available is given with comments on some of the disadvantages and complications attendant on their use. The potential dangers of staphylococcal sepsis and the need for rapid diagnosis and prompt vigorous treatment are stressed.
Resumption of estrogen-induced gonadotropin surges in postpartum monkeys.
Explore the source record for details and available documents.
Anovulation after pregnancy termination: ovarian versus hypothalamic-pituitary factors.
Explore the source record for details and available documents.
Necrotizing sialometaplasia after bronchoscopy.
Since the introduction of necrotizing sialometaplasia into the literature as a distinct pathologic entity in 1975, there have been several reports containing microscopic findings consistent with the disease primarily of the hard palate, but also of the soft palate, major salivary glands, retromolar pad of the mandible, and mucous glands of the nasal cavity. Localized ischemia appears to be a common link. All reported lesions heal with or without surgical intervention. Generous incisional biopsy specimens should be taken and aggressive surgery should be avoided.
Epidemioliogy of contact and non-contact meningococcal carrier rate in hospital patients.
Explore the source record for details and available documents.
Ovarian estradiol secretion during early pregnancy in monkeys: luteal versus extra-luteal secretion and effect of chorionic gonadotropin.
To determine the locus of ovarian estradiol secretion during early pregnancy, six monkeys were luteectomized (CLx) on days 22 to 24 of pregnancy. Daily peripheral serum concentrations of progesterone were maintained or slightly elevated despite removal of the corpus luteum (CL), while serum estradiol concentrations fell precipitiously (P less than 0.05). It is concluded that the CL of early pregnancy in these monkeys is the primary source of serum estradiol, but that ovarian tissues other than the primary luteal body secrete estradiol at low levels. Further, preliminary results suggest that mCG may be an important stimulus of ovarian estrogen secretion, by both luteal and extra-luteal compartments, in these primates. MCG may stimulate the CL to sustain estradiol secretion even after luteal cells are no longer responsive to this endogenous gonadotropin as regards progesterone secretion.
Reduction of granulosa cell progesterone secretion in vitro by intraovarian implants of antiandrogen.
Intra-ovarian Silastic implants containing the antiandrogen, Flutamide, or its active metabolite, reduced the level of progesterone secretion in porcine granulosa cell cultures by approximately 50%. These results complement recent observations in vitro suggesting a role for androgen in granulosa cell steroidogenesis during follicular development.
Changes in the chemistry of an isoalloxazine brought about by substitution at the 7 and 8 positions by a strongly electronegative substituent.
Explore the source record for details and available documents.
Kinetics and mechanisms of the 1,5-dihydroflavin reduction of carbonyl compounds and the flavin oxidation of alcohols. 4. Interconversion of formaldehyde and methanol.
Explore the source record for details and available documents.
Serum insulin response to slow-rise glucose infusion in "genetic prediabetics" (offspring of two diabetic parents).
The insulin response to a programed slow-rise glucose infusion designed to mimic the postprandial rise in glucose was studied in five offspring of two diabetic parents (ODP) and seven normal subjects. The ODP had higher mean blood glucose levels towards the end of the infusion and during the postinfusion period. The rates of glucose disappearance calculate during the postinfusion period were comparable in the two groups. Despite the apparent similarity of serum insulin levels of ODP and normal subjects, the amount of insulin secreted per unit of glycemic stimulus was lower in the ODP group. When the glucose infusion test was preceded by an acute load of glucose, similar findings in the insulin secretory dynamics were found in the ODP group. These data suggest that an impairment in insulin secretion exists in ODP when they are challenged by the slow rise of blood glucose achieved by this type of an intravenous glucose infusion.