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Biomedical subjects

R G Edwards

Publications and source records attributed to R G Edwards.

At least 217 records · Page 12Linked to original sources
PubMed1977

Steroidogenesis in human follicles approaching ovulation as judged from assays of follicular fluid.

Human chorionic gonadotrophin (HCG) was given to patients at mid-cycle before the endogenous LH surge. Graafian follicles were aspirated 32-33 h later, before ovulation was expected, and the levels of several steroids in follicular fluid and in matching serum samples were measured by radioimmunoassay. Two types of Graafian follicle were identified at laparoscopy , based on the nature of the oocyte, granulosa cells and follicular fluid withdrawn from the follicles. Some were large, preovulatory and presumably becoming luteinized while others were generally smaller, non-ovulatory and still growing. The concentrations of dehydroepiandrosterone (DHEA) and 17alpha-hydroxypregnenolone (delta5 intermediates), androstenedione and testosterone were higher in non-ovulatory follicles, whereas large follicles usually contained high levels of progesterone, 17alpha-hydroxyprogesterone, pregnenolone and oestradiol-17beta. A cluster analysis of these data grouped follicles into two distinct clusters, which accorded with their identification as ovulatory or non-ovulatory at laparoscopy. Levels of progesterone, 17alpha-hydroxyprogesterone and oestradiol-17beta in follicular fluid were high in preovulatory follicles in comparison with plasma. Results in two patients indicated that plasma levels of these steroids were determined by the preovulatory follicle. Levels of plasma delta5 steroids were closer to follicular fluid concentrations, whereas DHEA was higher in plasma. The role of the theca and granulosa is discussed in relation to the synthesis of progesterone and oestradiol-17beta in follicles as ovulation approaches.

Chorionic Gonadotropin↗
PubMed1976

The metabolism of the phosphonium analogue of choline in vitro and in vivo, and its detection in phospholipids by 31P-NMR.

1. The phosphonium analogues of choline, phosphorylcholine, CDPcholine and phosphatidylcholine were synthesized chemically and characterized by 1H-NMR and 31P-NMR; in 1,2-distearoyl-DL-glycero-3-phosphorylphosphocholine, the 31P-NMR chemical shift of phosphonium relative to phosphate was--28.2 ppm. 2. A comparison was made of the rates of reaction of choline kinase, cholinephosphate cytidyltransferase, cholinephosphotransferase and phospholipase C on natural and phosphonium substrates. Enzyme reaction rates were similar for all but the cytidyltransferase, which exhibited a 3-fold preference for the normal substrate. 3. Weanling rats were maintained for 6 weeks on a diet in which choline was fully replaced by phospho[1,2-14C2]choline mixed with a trace of [Me-3H] choline. Incorporation of phosphocholine into liver lipids was detectable by 31P-NMR even in crude tissue homogenates. Choline-based phospholipids of liver, kidney, lung and brain were extracted, and phosphocholine incorporation calculated from 31P-NMR peak area ratios. The phosphatidylcholine analogues were separated by preparative thin-layer chromatography. Incorporation of phosphocholine ranged from 33% in lung phosphatidylcholine to 6% in kidney sphingomyelin. Variations in 14C/3H ratio between feed and phospholipid extracts indicated preferences for exogenous choline over phosphocholine varying from 1.3: 1 in brain to 3.2: 1 in liver. The results indicated that phosphocholine is a potentially useful 31P-NMR probe for the study of membrane lipids.

Animals↗
PubMed1976

An evaluation of multiphasic screening on admission to hospital. Precis of a report to the National Health and Medical Research Council.

A controlled study of admission multiphasic screening (AMS) at a large general hospital showed that AMS had no significant effect on a variety of indices of inpatient progress. Owing to a 64% increase in estimated cost of investigations with AMS, the total hospital admission cost was increased by approximately 5%. Under the conditions of this study, AMS added to the cost of hospitalization without associated evidence of benefit to the patient.

Australia↗
PubMed1976

Reimplantation of a human embryo with subsequent tubal pregnancy.

A human embryo in transition between a morula and blastocyst after culture in vitro was reintroduced into the mother's uterus via the cervix. The resulting pregnancy was closely monitored and was found to be located in the oviduct. The ectopic embryo was removed at 13 weeks gestation.

Adult↗
PubMed1976

An analytical model for ovarian follicle dynamics.

Differential counts of follicles of different sizes in the ovaries of intact and hypophysectomized strain A mice of various ages have been analysed statistically. The influence of age on the number of follicles in each size group is described. The number of small follicles in the ovarian pool declined exponentially, whereas numbers of follicles in other groups displayed two peaks, one during immaturity and the other in adult life. These appeared sequentially in follicles in successive groups. The proportion of follicles growing and dying was estimated and age dependent fluctuations in the time spent by follicles in each group were demonstrated. Further calculations then determined the mean inflow and outflow of follicles to and from the various groups throughout the lifespan. Hypophysectomy during post-puberty decreased only slightly the utilization of small follicles from the pool and did not prevent their subsequent development to the two-layered stage. Many follicles then died at this stage of development, indicating that the initial main site of gonadotrophic action may be on medium sized follicles with two layers of granulosa cells.

Animals↗
PubMed1976

Oxalate excretion during carbohydrate infusions.

Oxalate metabolism was assessed in normal rats and rats deficient in vitamins B-1 and B-6 during intravenous infusions of solutions containing glucose, fructose, sorbitol or xylitol. Urinary excretions of oxalate, glyoxylate and glycine were considerably increased in vitamin B-6 deficient rats infused with xylitol. Significant amounts of 14C-oxalate were excreted only in vitamin B-6 deficient rats infused with U 14C-xylitol. Correction of vitamin B-6 deficiency resulted in a return to normal of urinary oxalate excretion and percentage of U 14C-xylitol excreted as 14C-oxalate. The results suggest that xylitol metabolism produces an increased activity in pathways leading to oxalate formation in vitamin B-6 deficient rats.

Animals↗
PubMed1976

Evaluation of benefits of screening tests done immediately on admission to hospital.

Evidence was sought of improved inpatient progress and reduced hospital costs when a battery of investigations were done at the time a patient was admitted to hospital. The outcome in 500 admission-tested patients was compared with that in two other groups of 500 control patients. No significant differences were found among the three groups in a variety of indices of inpatient progress. Because of an estimated 64% increase in the cost of investigating inpatients with admission testing, the total cost of hospital care was increased by about 5%. Under the conditions of this study, admission testing added to the cost of hospitalization, without associated evidence of benefit to the patient.

Australia↗
PubMed1975

The purification and properties of a beta-N-acetylhexosaminidase from Trichomonas foetus.

A beta-N-acetylhexosaminidase was purified 800-fold from extracts of Trichomonas foetus by affinity chromatography on a column of N-(epsilon-aminohexanoyl)-2-acetamido-2-deoxy-beta-D-glucopyranosylamine bound to CNBr-activated Sepharose. The enzyme has a dual specificity for the p-nitrophenyl beta-D-glycosides of N-acetylglucosamine and N-acetyl-galactosamine. The parent sugars are both competitive inhibitors. The enzyme has a mol. wt. approx. 150000 and a pH optimum of 6.2. It is suggested that the same active site catalyses both activities and that no part is played by the 4-hydroxyl group in substrate binding, but it is involved in determining the catalytic rate.

Acetylgalactosamine↗
PubMed1975

Ultrastructural relationships between decidua, trophoblast and lymphocytes at the beginning of human pregnancy.

Between the 20th and 40th day of pregnancy, human decidual cells in the endometrial connective tissue come into direct contact with the trophoblastic cells eroding the stromal tissue. Fibrillar deposits of maternal origin were randomly distributed between the maternal and fetal sites and did not form a continuous barrier. Structural features were prominent in the maternal and embryonic cells. Large decidual cells were intermingled with trophoblastic cells, and there was little intercellular material. Small developing decidual cells arose around the maternal precapillary arterioles and capillaries and were closely accompanied by lymphocytes. Fully developed decidual cells exhibited a fine structure characteristic of a state of active secretion, and trophoblastic cells gave structural indications of producing protein. The aggregates of decidual and trophoblastic cells in the human endometrium during early pregnancy ('deciduotrophoblastic complex') may function as a local humoral regulator releasing chemical factors and partaking in the establishment of immunological privilege at implantation.

Animals↗
PubMed1975

Induction of follicular growth, ovulation and luteinization in the human ovary.

Studies on human ovulation are described, in which follicular growth and ovulation were controlled by HMG, clomiphene and HCG. Three regimes of treatment were employed: several injections of HMG, followed by an injection of HCG, a course of clomiphene followed by an injection of HCG and an injection of HCG alone timed to just pre-date the surge of LH during the natural cycle. Aspects of follicular growth and the timing of ovulation have been studied following the use of these treatments. Follicles rupture some 37 hr after the injection of HCG in cycles where HMG or clomiphene were used to stimulate follicular growth. The timing of ovulation was established with less precision when HCG was used to induce ovulation in the natural cycle, since the LH surge sometimes occurred before HCG was injected and other problems arose during luteinization. The numbers of follicles growing in response to stimulation with clomiphene or HMG showed only a slight relationship to the levels of oestrogen excreted in urine. The morphology of the preovulatory follicle was noted and some biochemical and physiological parameters were measured, including the levels of various steroids and prostaglandins in follicular fluid. The morphology of the oocyte and granulosa cells was recorded. These observations are discussed in relation to several physiological and clinical aspects of ovarian activity: the regulation of follicular growth, the timing of ovulation following the LH surge, factors affecting ovulation, and the relation of studies on follicular growth and ovulation to the rhythm method of contraception and other medical situations.

Chorionic Gonadotropin↗