Biomedical subjects
Publications and source records attributed to R Mitchell.
This is the first British patient to be reported with the rhesus null phenotype. Anti-Rh 29 was detected in a primigravida at 35 weeks' gestation and rose substantially before delivery. She had all the features of the rhesus null syndrome and her newborn was affected by haemolytic disease (HDN).
Passive haemagglutination inhibition (PHI) was adapted to quantitate red cell associated IgG. Twenty one patients with autoimmune haemolytic anaemia (AIHA) had a raised red cell associated IgG, mean (SD) = 5.783 (6.183) ng/10(6) red blood cell compared with that of 69 subjects with a red cell associated IgG of 0.433 (0.349) ng/10(6) red blood cell. Thirteen of 14 blood donors with a positive direct antiglobulin test (DAGT) had a normal red cell associated IgG. The only blood donor with positive DAGT and raised red cell associated IgG had AIHA. Studies of red cell associated IgG in other groups of patients were also undertaken. The technique is simple, does not require the use of sophisticated equipment, and is suitable as a routine test in hospital laboratories. The results of red cell associated IgG by PHI are reproducible and clinically relevant.
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Two cases of pubic osteomyelitis presenting as a painful hip are reported. In both cases the diagnosis was delayed by the unusual presentation and by the limited radiological investigation. Pubic osteomyelitis is rare in childhood but should be considered in the differential diagnosis of the 'irritable hip'.
A total of 45 patients with the painful heel syndrome without evidence of an associated inflammatory arthritis, seven of whom had pain in both heels, were studied using technetium-99 isotope bone scans and lateral and 45 degrees medial oblique radiographs of both feet. Of the 52 painful heels 31 (59.6%) showed increased uptake of tracer at the calcaneum. Patients with scans showing increased uptake tended to have more severe heel pain and responded more frequently to a local hydrocortisone injection. On plain x-ray, 39 of 52 painful heels (75%) and 24 of the 38 opposite nonpainful heels (63%) showed plantar spurs, compared with five of 63 (7.9%) heels in 59 age- and sex-matched controls. No evidence of stress fractures was seen.
Cultured bovine granulosa cells express the gene encoding basic fibroblast growth factor (bFGF). The bFGF gene is transcribed into 7.0- and 3.7-kilobase mRNA transcripts which are apparently translated into 16,000 mol wt bFGF-like growth factor. The granulosa cell-derived bFGF is bioactive, i.e. it can stimulate the proliferation of capillary endothelial or granulosa cells. This mitogenic effect is prevented by specific neutralizing anti-bFGF antibodies. Our results indicate that bFGF derived from granulosa cells can act as both autocrine and paracrine growth factor, and they further suggest that the factor may be involved in the development of the rich vasculature of the theca interna of the follicle.
The calculation of femoral anteversion using a static ultrasound scanner has been compared with results obtained by computer tomographic (CT) scanning. Assuming the CT results to be accurate, the ultrasound method was frequently found to be unreliable.
The effect of etomidate (an anaesthetic), epostane (WIN 32729; an inhibitor of ovarian and adrenal steroidogenesis) and cyproterone acetate (an antiandrogen) on testosterone secretion from mouse Leydig cells stimulated with LH (5 i.u./l) was tested. The concentration of drug which inhibited testosterone secretion by 50% was 11.5 +/- 1.1 (S.E.M.) mumol/l for cyproterone acetate, 1.2 +/- 0.2 mumol/l for etomidate and 0.23 +/- 0.03 mumol/l for epostane. The effect of all three drugs on testicular steroidogenesis was completely reversible. Thus testicular cells which had been washed after exposure to a greater than 95% inhibitory dose of drug responded in a similar manner to hormone stimulation as cells similarly washed and which had not been exposed to the drug. The sites of the antisteroidogenic effect of epostane, etomidate and cyproterone acetate were established using a method based on the sequential stimulation by the exogenous precursor steroids of the various steps leading to the biosynthesis of testosterone. It was concluded that etomidate acts at the sequence between LH binding and pregnenolone production, epostane acts at 3 beta-hydroxysteroid dehydrogenase and cyproterone acetate inhibits 3 beta-hydroxysteroid dehydrogenase and C17,20-lyase.
The LHRH receptor has been solubilized from male rat anterior pituitary glands, using the zwitterionic detergent 3-((3-cholamidopropyl)-dimethylammonio)-1-propanesulphonate in the presence of a high concentration of sodium chloride. This method gave high yields (up to greater than 70%) of the LHRH-binding site from the membrane preparation. Ligand binding studies using LHRH analogues were carried out to determine dissociation constants for LHRH receptors both in situ in the membrane preparation and for solubilized LHRH receptors. For all the analogues the binding characteristics were similar in both preparations, suggesting that the solubilization procedure left the LHRH receptor undenatured. Gel filtration revealed an apparent molecular weight for the LHRH receptor of 100,000-160,000, with the mean value being approximately twice that found by others using sodium dodecyl sulphate-polyacrylamide gel electrophoretic techniques. The results indicate that the LHRH receptor probably exists in gonadotroph membranes as a large complex of more than one subunit.
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The densities of trabecular and cortical bone in the radius were measured by computed tomography in 40 women with generalized osteoarthrosis (osteoarthritis, GOA), and the results were compared to normal values obtained from prediction equations. When age, weight and height were considered, no significant differences were observed between patients with GOA and normal controls. But when age only was considered, trabecular bone density in the distal radius was found to be 7% higher than predicted (p less than 0.05). Increased trabecular bone density is unlikely to be an etiopathogenetic factor in GOA although this cannot be completely excluded from our study.
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The effect of the anti-fungal agent, ketoconazole, on cortisol secretion from adrenal cells stimulated with ACTH (1-24, 50 ng/l) and on testosterone secretion from Leydig cells stimulated with LH (5 i.u./l), has been tested. The concentration of drug which inhibited cortisol and testosterone secretion by 50% (ED50) was 3.6 +/- 0.7 mumol/l and 0.61 +/- 0.03 mumol/l, respectively. The effect of ketoconazole on adrenal and testicular steroidogenesis was completely reversible. Thus, adrenal and testicular cells which had been washed after exposure to greater than 95% inhibitory dose of ketoconazole responded in a similar manner to hormone stimulation as cells similarly washed and which had not been exposed to drug. The sites of the anti-steroidogenic effect of ketoconazole have been established using a method based upon the sequential stimulation by the exogenous precursor steroids of the various steps leading to the biosynthesis of cortisol by adrenal cells and testosterone by Leydig cells. We conclude that ketoconazole reversibly inhibits the sequence between ACTH/LH binding and pregnenolone production and also inhibits testicular C-17-C-20, lyase activity.
The observation in this laboratory that respiration and Sr2+ import were stimulated by the addition of 3-hydroxybutyrate to suspensions of N-ethylmaleimide-treated mitochondria respiring in state 6, after the addition of Sr2+, in a sucrose medium containing choline as substrate, led to the proposal by Moyle and Mitchell [(1977) FEBS Lett. 84, 135-140] that there is a Ca2+(Sr2+)-3-hydroxybutyrate symporter in rat liver mitochondria. However, experiments described in the present paper support a different interpretation. Under the conditions of the experiments by Moyle and Mitchell, the rate of respiration and the poise of Sr2+ accumulation are mainly limited, not by delta mu H+, but by lack of respiratory substrate. Even though N-ethylmaleimide is a potent inhibitor of 3-hydroxybutyrate dehydrogenase, we have found that, somewhat surprisingly, under the special conditions of these experiments, sufficient 3-hydroxybutyrate dehydrogenase activity remains available to account for the 3-hydroxybutyrate-dependent respiratory stimulation and Sr2+ import.
When O2 was injected into an anaerobic suspension of valinomycin-treated rat liver mitochondria inhibited with rotenone, antimycin, and myxothiazol, a small amount of O2 (0.23-0.33 ng-atom of O/mg of protein) was reduced extremely rapidly (within the 2 s time-resolution of the oxygen electrode). The subsequent steady-state rate of flow of electrons to oxygen was very low [less than 3 nequiv. X s-1 X (g of mitochondrial protein)-1]. In the presence of valinomycin there was a rapid ejection of protons synchronous with the rapid phase of O2 consumption corresponding to 0.38-0.61 nequiv. of H+ X (mg of mitochondrial protein)-1. When valinomycin was replaced by carbonyl cyanide p-trifluoromethoxyphenylhydrazone (FCCP) there was a rapid alkalification of the medium corresponding to 0.20-0.42 nequiv. of H+ X (mg of mitochondrial protein)-1. When 2 mM-Fe(CN)6(4-) was present to re-reduce endogenous cytochrome c, O2 consumption was still biphasic but the second phase of O2 consumption was very much more rapid [600 nequiv. X s-1 X (g of protein)-1], and resulted in the virtually complete consumption of the O2 in the pulse within 4 s. With 60 microM-Ru(NH3)6(2+) as reductant, O2 consumption was even faster [1200 nequiv. X s-1 X (g of protein)-1]. In a medium containing 150 mM-choline chloride with Ru(NH3)6(2+) as reductant, the proton per reducing equivalent stoichiometry (delta H+O/e-) was +0.95 in the presence of valinomycin and -0.94 in the presence of FCCP. In choline chloride medium containing Ru(NH3)6(2+) and valinomycin, there was an uptake of K+ ions corresponding to 1.86 K+/e-. It is concluded that nearly 1 proton is translocated outwards through cytochrome oxidase per oxidizing equivalent injected in this medium. In low ionic strength sucrose-based medium, with Ru(NH3)6(2+) as reductant, delta H+O/e- was 1.05 in the presence of valinomycin, and -0.71 in the presence of FCCP. It is concluded that the translocation of protons is accompanied by net acid production in this medium.
The effects of GABA receptor agonists on prolactin secretion in vitro was examined using a rapid superfusion system. GABA and muscimol caused a biphasic effect on prolactin secretion, both components of which were antagonised by bicuculline methiodide, while baclofen had no effect on basal or stimulated secretion, demonstrating the GABAA receptor specificity of both components. Homocarnosine caused only inhibition of secretion, and a range of partly rigid GABA analogues were relatively poor at causing stimulation of secretion. Both effects of muscimol were antagonised by low-chloride medium and the anion channel blocker DIDS, but strychnine and picrotoxinin were both potent and selective antagonists of the stimulatory effect. These results demonstrate a novel biphasic effect of GABAA agonists or prolactin secretion, the two components of which appear to be independent and mediated by different types or states of GABAA receptor/chloride channel complex.
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The apparent proton-motive stoichiometry as measured by the oxygen-pulse technique in KCl medium is depressed by the rapid uptake of inorganic phosphate, unless endogenous phosphate is depleted or uptake is inhibited. In sucrose or choline chloride media, where the internal pH is more acid than in KCl media, uptake may be greatly diminished. In the absence of significant phosphate uptake, the observed stoichiometry of around 8, obtained with no added substrate or respiratory inhibitors, appears to be characteristic of NADH oxidation without significant participation of the proton-translocating NAD(P) transhydrogenase. A mechanistic stoichiometry of at least 8 is indicated.