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Biomedical subjects

J M Rees

Publications and source records attributed to J M Rees.

At least 37 records · Page 2Linked to original sources
PubMed1988

An evaluation of the role of relaxin in the penetration of cervical mucus by spermatozoa.

Relaxin-like immunoreactivity was measured in seminal plasma from men who were separated into two groups, on the basis of a previous positive or negative result in a postcoital cervical mucus penetration test. There was no difference in the relaxin concentration between the groups. The effect of exogenous porcine relaxin (0, 10 or 100 ng/ml) on human cervical mucus penetration in vitro by washed human spermatozoa was studied using a capillary tube preparation. In the positive postcoital test group the highest relaxin concentration (100 ng/ml) tended to inhibit cervical mucus penetration, although this effect was only significant for one of the parameters measured (number of spermatozoa penetrating to the 10-mm mark). The same trend was apparent for the negative postcoital test group, but no differences were significant. The results are in direct contrast to previous reports that relaxin can stimulate human spermatozoa motility and cervical mucus penetration.

Cervix Mucus↗
PubMed1988

Identification of relaxin in the placenta of the ewe.

Sheep placentomes were collected at the abattoir and the stage of gestation was estimated from the crown-rump length and appearance of the fetus. Samples were extracted and either freeze dried (crude extracts) or fractionated on Sephadex G-50 and CM-cellulose. Relaxin immunoreactivity (RXN-IR) was detected in all samples by a pig relaxin RIA and diluted in parallel with the standard curve. Two patterns of RXN-IR were seen after Sephadex G50 purification: (a) a single main peak of RXN-IR eluting at a position similar to pig relaxin; or (b) a 3-peak pattern with additional higher (void volume) and lower (approximately 1000) molecular weight peaks. These peaks were all found with 4 different and specific antisera. The 6000 molecular weight peak eluted at a similar position to pig relaxin on CM cellulose and inhibited electrically stimulated rat uterine contractions in vitro. The amount of relaxin measured in crude extracts of placentomes from different ewes was very variable. Most samples were within the range 0.05-11.2 ng/g wet weight of tissue (3.0 +/- 0.45 (s.e.m.), n = 44) but a few contained much higher concentrations (25.5-61.4 ng/g, n = 3). There was no obvious variation in concentration with stage of pregnancy (20 days to term). Samples of intercotyledonary endometrium, allantochorion and whole ovaries from pregnant ewes were also extracted. All contained low concentrations of RXN-IR (0.6 +/- 0.13 ng/g, n = 4; 0.6 +/- 0.29 ng/g, n = 3; 1.0 +/- 0.66 ng/g, n = 7, respectively). We conclude that relaxin-like peptides are present in the pregnant ewe and that, as the placentomes are the largest component by weight, they represent the major source.

Animals↗
PubMed1987

The role of mean corpuscular haemoglobin concentration in limiting the storage life of human blood.

Human erythrocytes stored for more than 21 days in citrate phosphate dextrose with adenine (CPDA-1) at +4 degrees C had a decreased cell volume, an increased cell density, an elevated mean corpuscular haemoglobin concentration (MCHC) and hence an elevated internal viscosity. These changes are normally masked by the reversible cell swelling which accompanies storage in CPDA-1. Incubation of stored cells for 24 h at 37 degrees C in fresh autologous plasma mimics the effects of reinfusion and causes the artificially swollen cells to shrink to their true volume. Thus, incubated cells which had been stored in CPDA-1 for more than 21 days exhibited a decreased filterability through Nuclepore membranes in vitro, which is apparently correlated with a decreased survival time in vivo.

Adenine↗
PubMed1987

The use of nystatin to restore the flow properties of time-expired stored erythrocytes.

Human erythrocytes stored for more than 21 days in citrate phosphate dextrose with adenine (CPDA-1) exhibited a marked reduction in volume following incubation for 24 h at 37 degrees C in fresh autologous plasma. This incubation apparently mimics the effects of reinfusion of the stored cells in vivo. These shrunken stored cells have a decreased filterability as measured by their increased transit times through a 5-microns diameter Nuclepore filter. The polyene antifungal agent nystatin was used to reinflate these shrunken cells with different concentrations of potassium ions. A concentration of 90 mM potassium chloride was found to reinflate the shrunken stored cells so that their mean cell volume, mean corpuscular haemoglobin concentration and average densities were the same as those of fresh cells. This reinflation also restored the filterability of the shrunken stored cells so as to be similar to that of fresh cells.

Adenine↗
PubMed1987

The effects of reinflation on the survival of time-expired stored rabbit erythrocytes in vivo.

Rabbit blood cells stored for prolonged periods in citrate phosphate dextrose with adenine (CPDA-1) at +4 degrees C show the same decreased volume, increased cell density and decreased filterability as human cells stored under similar conditions. As with human erythrocytes, the stored rabbit cells had to be incubated with autologous fresh plasma for 24 h at 37 degrees C before these changes could be observed (this incubation process apparently mimics the effects of reinfusion). These shrunken stored rabbit cells could also be reinflated using nystatin, so that their mean cell volume, mean corpuscular haemoglobin concentration, average cell densities and filterabilities were restored to normal values. This in vitro reinflation of the stored cells significantly prolonged their in vivo survival rate as determined by radiochromium labelling studies. This reinflation technique may therefore have an application in the prolongation of the useful storage life of human blood.

Adenine↗
PubMed1987

Health, developmental, and nutritional status of adolescent alcohol and marijuana abusers.

The impact of alcohol and marijuana abuse on the physical health and nutritional status of adolescents has not been well documented. The health consequences of alcoholism and chemical abuse in adults may not relate to the pediatric population. Forty-nine adolescent boys (mean age 15.8 years) with varying degrees of alcohol and marijuana use by self-report were evaluated as to their general health, pubertal development and nutritional status using health and dietary history, physical examination, anthropometrics, and biochemical assays of liver function and tissue nutrients. Thirteen (27%) were alcohol and marijuana abusers, 20 (41%) marijuana abusers, and 16 (32%) nonusers. There were significant differences between alcohol and marijuana abusers and marijuana abusers compared to nonusers with respect to endorsing symptoms of nutritional deficiency (muscle weakness, bleeding gums, tiredness, etc) (P less than .001). There were no significant differences between subgroups in other nutritional measures except plasma zinc concentration which was low in marijuana abusers (mean 85 micrograms/dL). All adolescents reported consuming adequate nutrients, although alcohol and marijuana abusers reported eating more snack foods and less fruit, vegetables, and milk than other groups. There were no significant differences in hematologic status (complete blood cell count, transferrin, folate), liver function (gamma-glutamyltranspeptidase), or anthropometric and sexual maturational indices of growth. There were no chronic signs of chemical abuse by physical examinations. It appears that health and nutritional disability from chemical abuse in adolescents relates more to poor dietary habits and symptomatic deterioration in general health than to specific effects on growth or nutritional status. Studies with larger numbers of subjects need to document these findings.

Adolescent↗
PubMed1986

Identification of relaxin immunoreactivity in human follicular fluid.

Relaxin immunoreactivity has been found in samples of human follicular fluid collected from artificially stimulated pre-ovulatory follicles. The crude extract caused a reduction in the height of the contractions in a rat uterine strip bioassay. The reactive material eluted from Sephadex G50 in two major peaks. The first contained approximately 60% of the immunoreactivity and had an elution position corresponding to that of porcine relaxin, indicating a mol. wt of approximately 6000 daltons. The second peak was of a lower mol. wt, but its exact size and significance are unknown. A possible role for relaxin in the process of follicular rupture is suggested.

Biological Assay↗
PubMed1985

The effects of 50 Hz magnetic fields on opioid peptide mediated inhibition of guinea pig ileum.

Strips of guinea pig ileum were mounted in a tissue bath within the poles of a magnet capable of generating a 50 Hz field of intensity up to 1 mT. In the absence of magnetic field the preparations were stimulated transmurally at tetanic frequency (10 Hz). The post-tetanic inhibition was antagonised by naloxone. When this inhibitory phase was repeated in the presence of a magnetic field of 0.5 mT there was a small but significant increase in the inhibition when compared with paired controls.

Animals↗
PubMed1985

Changes in plasma opioid concentrations after physiotherapeutic exercises for arthritic patients.

Plasma concentrations of [met]enkephalin (ME) and beta-endorphin (beta E) were measured in samples obtained immediately before and after physiotherapeutic exercises for patients with ankylosing spondylitis (AS), osteoarthritis (OA), or knee injuries. Correlations were sought between opioid peptide concentrations or changes therein, and nature, severity and duration of disease, age, severity of pain reported and pain threshold. No correlation was found with any of the pain parameters. However, there was a possible relationship between age or duration of disease and changes in ME concentrations.

Adult↗
PubMed1985

Iron fortification of infant foods. A decade of change.

A survey of iron-fortified commercial foods commonly marketed for consumption by infants was conducted in 1972 and again in 1982. Positive changes had occurred in infant formulas and cereals during that decade, in availability of fortifying iron, level of fortification, and label information. Miscellaneous iron-containing products, cookies, and crackers were unreliable sources of dietary iron in both 1972 and 1982. Availability of fortifying iron in regular cereals had improved by 1982, though 10 percent lacked the label information. Fortified infant formulas and cereals contribute iron of high bioavailability to the typical infant diet in amounts equal to the USRDA. Food manufacturers need to continue to apply knowledge gained through research to sustain the lessened but still highly prevalent incidence of anemia in 1-2-year old children.

Biological Availability↗
PubMed1984

Prenatal weight gain and postpartum weight loss patterns in adolescents.

The standard weight gain curve for pregnant females is used for all ages but its suitability for pregnant adolescents has not been satisfactorily examined. The purpose of this project was to compare prenatal weight gain patterns of 80 adolescents (13-17 yr old) with those of the standard curve. Girls who were chronologically and physiologically younger tended to gain less weight prenatally then older girls. Girls who were underweight prior to pregnancy gained more weight prenatally than other girls. Term weight gain averaged 37 lb. Increase in height was not recorded during the course of the investigation. The development of standard curves for adolescents must be based on a larger study population, but the curves presented here are an important initial step toward achieving this goal.

Adolescent↗
PubMed1984

The effects of phenylpropanolamine and other sympathomimetics on food consumption and motor activity in mice.

The effects of phenylpropanolamine on motor activity and on food intake were compared with those of S-amphetamine, ephedrine, 2-aminoindane and fenfluramine in groups of mice. Motor activity was additionally measured in mice pretreated with levodopa and benserazide, and food intake in mice pretreated with alpha-methyl-p-tyrosine. Amphetamine (2.5 mg kg-1) increased motor activity, phenylpropanolamine (10-40 mg kg-1) and 2-aminoindane (2.5-10 mg kg-1) decreased activity whilst ephedrine (2.5-40 mg kg-1) had a biphasic effect. Fenfluramine (10-40 mg kg-1) had negligible effect on activity. In mice pretreated with levodopa and benserazide both phenylpropanolamine and 2-aminoindane caused a massive increase in motor activity whilst fenfluramine's action was not affected in the same way. Whilst the anorectic action of fenfluramine was considerably potentiated in mice pretreated with alpha-methyl-p-tyrosine, that of amphetamine, ephedrine, 2-aminoindane and phenylpropanolamine was either unaffected or initially antagonized. It is concluded that the mechanisms of motor and anorectic actions of phenylpropanolamine are similar to those of amphetamine.

Animals↗
PubMed1980

Sympathomimetic effects of exo- and endo-isomers of 2-aminobenzonorbornene in vitro and in vivo.

A stereospecific synthesis of endo-2-aminobenzornorbornene is described. Its sympathomimetic activities and those of its N-methyl derivative were compared with the equivalent exo-isomers using the isolated rat anococcygeus muscle and the anaesthetized rat blood pressure preparations. On the anococcygeus muscle preparation the endo- and exo-isomers of the primary amines had similar indirectly acting sympathomimetic activities. In contrast the exo-N-methyl derivative was a far more potent sympathometic in vitro than the endo-N-methyl isomer. In the anaesthetized rat the exo- and endo-isomers of 2-aminobenzonorbornene and their N-methyl derivatives all had similar pressor activities, though the successive injections of the two exo-derivatives suggested an additional alpha-adrenoceptor blocking activity. The actions of these rigid sympathomimetics are compared with those of the flexible amphetamine structure.

Amphetamine↗
PubMed1980

In vitro actions of NN-dimethyl-2-aminoindane and related compounds.

The actions of 2-aminoindane, 2-amino-1,2,3,4-tetrahydronaphthalene and amphetamine and their N-methyl and NN-dimethyl derivatives on the guinea-pig ileum were compared. All, except the tertiary 2-aminoindane, inhibited the responses to electrical stimulation and it is suggested that this is not fully explained by their sympathomimetic properties. NN-Diemthyl-2-aminoindane increased these responses and caused contractions of the unstimulated ileum due to a nicotine-like action. The indane series was more effective in producing contractions of the ileum than the other compounds. The three tertiary derivatives antagonized competitively the actions of histamine on the ileum and those of 5-hydroxy-tryptamine on the rat uterus.

Acetylcholinesterase↗