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Biomedical subjects

M Ryle

Publications and source records attributed to M Ryle.

At least 19 recordsLinked to original sources
PubMed1989

Enzyme activation of human prolactin: a potential basis for a bioassay.

Small cultures of human amniotic cells were preincubated for 24 h. Human prolactin was then added to the medium. After a further short period of incubation the tubes were chilled, the medium removed and the cells rinsed with saline. The tubes then received cold Tris-sucrose and were frozen, to disrupt the cells. After thawing, adenosine triphosphatase (ATPase) and p-nitrophenyl phosphatase (PNPase) were measured. Buffer was added containing either ATP or PNP and the tubes were incubated for 30 min. Inorganic phosphate released from ATP and p-nitrophenol was measured spectrophotometrically. Prolactin stimulated both enzyme activities. The ATPase log dose-response curve was linear between approximately 12.5 and 200 mIU/l. It was inhibited by ouabain. Isobutyl-1-methylxanthine inhibited the ATPase but not the alkaline phosphatase activity. One of these human amniotic cell enzymes may provide the basis for a sensitive bioassay for human prolactin.

1-Methyl-3-isobutylxanthine↗
PubMed1982

Plasma prolactin concentrations during conception and the first ten weeks of human pregnancy.

Plasma prolactin concentrations were measured daily throughout 20 cycles in which conception occurred and for several weeks during early pregnancy. Thirteen of the pregnancies were 'spontaneous' (i.e. without exogenous pharmacological stimulation) and 7 occurred during either clomiphene or bromocriptine treatment. Prolactin concentrations were fairly stable throughout the conception cycles until shortly after the time of the first missed menses. From this time concentrations rose gradually to reach a mean concentration of 1250 mU/l 60 days after ovulation. However, there were marked fluctuations from day to day within individuals and considerable variation in the magnitude of the prolactin rise between subjects. Three subjects were mildly hyperprolactinaemic and although prolactin levels remained slightly elevated throughout the study period, this did not affect the outcome of pregnancies.

Bromocriptine↗
PubMed1981

A new approach for assaying LH by using a target cell response.

Replicate cultures of 50000 mouse Leydig cells were used to obtain linear log dose-response curves to LH. This hormone augmented the activity of an endogenous alkaline phosphatase, which was subsequently allowed to act on p-nitrophenyl phosphate, the coloured end-point being measured with a spectrophotometer. The linear portion of the curve extended from 0.2 to 3.2 mi.u. LH/ml.

4-Nitrophenylphosphatase↗
PubMed1980

Producing mice for bioassays.

Groups of breeding females were caged together for 3 weeks before putting them (1 or 2 per small box) with males, for 4-5 days. They were then pooled again until shortly before parturition. The majority of pups were born 22 or 23 days after pairing and were reared in foster litters, usually consisting of 27 pups with 3 foster mothers. Non-pregnant females and those not required as foster mothers were pooled once more. All pups were weaned on the same day, 19 or 20 days after birth, when all females were again mated. The average production rate was approximately 4 usable pup per female in the batch every 6 weeks. By maintaining 3 asynchronous batches of females a regular fortnightly supply of experimental animals was maintained with minimum wastage of food and labour.

Animals↗
PubMed1978

Parallel competitive binding and metabolic endpoint assays for hCG based on rabbit granulosa cells.

A competitive binding assay for hCG is described, in which live rabbit granulosa cells adhering to small tubes provide solid-phase binding sites. Parallel assays, in which the synthesis of progestagens and the incorporation of [3H]acetate into lipid serve as endpoints, are also described. The assays are sensitive, reproducible and precise and should be both economical and convenient for studies on the relationship between the molecular structure and the biological activity of hCG and LH.

Acetates↗
PubMed1977

Economics of alternative energy sources.

An important part of the oil and natural gas at present consumed in the UK is used for the heating of buildings, a demand which shows large diurnal, day-to-day and annual fluctuations. The replacement of this energy by nuclear-generated electricity, as at present envisaged, would require the construction of some 250 GW of additional capacity by the end of the century, a progamme which does not seem feasible. By incorporating relatively cheap, short term storage in the form of low-grade heat, the generating capacity required to fulfil peak demand could be reduced by more than 50%. As soon as such storage is provided, however, other sources of energy become viable and attractive alternatives, and the UK is well situated to make use of wind, wave, and tidal power. It seems likely that the value of North Sea oil/gas reserves as feedstock to the chemical industry will rise sufficiently to make an early reduction in their consumption as fuel of great economic importance.

Journal Article↗
PubMed1975

Serum gonadotrophins in young children.

LH and FSH were assayed in serum samples from children ranging from newborn to 13 years. In boys, LH was found in most samples up to 4 months of age, in many up to 10 months, but in only 38 percent between 1 and 8 years. In girls, it was found in only 29 percent of the samples under 1 year and the frequency and concentration changed little thereafter until 8-10 years. FSH was detected in all samples from boys up to 4 months and in most of those from girls up to 2 years. After these ages the frequency declined in each sex and there was little further change until 8-10 years. Between 1 and 8 years the proportion of samples containing either FSH or LH was similar for the two sexes, but whereas in boys high LH tended to be associated with high FSH, and vice versa, there was no such correlation in girls. The results are discussed in relation to gonadal development and steroid synthesis.

Adolescent↗
PubMed1975

Histochemical studies on three gonadotrophin-responsive enzymes in the infantile mouse ovary.

The activities of alkaline phosphatase, NAD diaphorase and NADP diaphorase increased in infantile mouse ovaries in response to injected gonadotrophins. The distribution and activity of these enzymes were studied in detail in the ovaries of normal mice from 1 to 41 days after birth and in mice injected at various ages with FSH, LH and HCG. Granulosa cells contained NAD and NADP diaphorases. Thecal cells contained NADP diaphorase and alkaline phosphatase with NAD diaphorase first appearing in the thecae of larger follicles 11 days after birth. All three enzymes occurred in interstitial tissue, in the interfollicular stroma and in groups of gonadotrophin-responsive cells in the medulla. These medullary cells and the interstitial tissue were stimulated by exogenous LH and HCG but not by FSH. Granulosa, theca and interfollicular tissue were stimulated at some stage by each of the three injected hormones. The normal pattern of development is discussed in relation to the changing serum levels of endogenous gonadotrophin found in similar mice. It is concluded that the enzyme changes were closely and reciprocally related to endogenous hormone concentrations.

Age Factors↗
PubMed1975

Gonadotrophic stimulation of oestrogen synthesis by cultured immature mouse ovaries.

The amount of oestrogen produced by immature mouse ovaries cultured with purified gonadotrophins was measured by means of a radioimmunoassay. Small quantities were released in response to FSH or LH alone, but when both were provided production was greatly enhanced after an initial lag phase of 2-3 days. The lowest concentrations required to produce this synergistic effect were between 0-02 and 0-13 i.u. FSH/ml and between 0-01 and 0-1 i.u. LH/ml. After prolonged exposure to 0-4 i.u. FSH/ml plus 1-0 i.u. LH/ml, oestrogen output continued to rise until, on the ninth day of culture, it reached 2-6-7-3 ng/ovary/day. Pre-treatment with 0-4 i.u. FSH/ml for 3 days enhanced the subsequent response to combined gonadotrophins but the simultaneous presence of FSH and LH was essential for inducing the delayed synergistic effect. Although both gonadotropins also stimulated follicle growth there was no evidence suggesting any simple correlation between that response and oestrogen synthesis. Maximal oestrogen production coincided with very low follicular mitotic activity.

Animals↗