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Biomedical subjects

A Martin

Publications and source records attributed to A Martin.

At least 703 records · Page 39Linked to original sources
PubMed1986

Modulation of alpha 2-acute phase globulin serum concentration in turpentine- and immune complex-challenged rats by dexamethasone and adrenaline: evidence for a synergistic mode of action.

The acute phase response (APR) induced by immune complexes or turpentine and modulated by dexamethasone as well as adrenaline was investigated in intact, sham-adrenalectomized and adrenalectomized rats. The serum level of alpha 2-acute phase globulin was examined by means of electroimmunodiffusion, and the complex serum protein profile was studied using the crossed-IE. Dexamethasone administration increased the alpha 2-acute phase globulin concentration weakly over a wide dose range whereas rats dosed with adrenaline responded strongly over a small dose range. Turpentine but not immune complex challenge provoked an almost complete acute phase protein profile as well as a moderate alpha 2-acute phase globulin elevation in adrenalectomized rats. After combined administration of the prophlogistic agents and dexamethasone or adrenaline a remarkably high alpha 2-acute phase globulin level was found (up to 14 mg/ml with about 0.05 mg/ml as base level). From these results a synergistic mode of action can be suggested. With crossed-IE some of the proteins could by divided in proteins responding in a glucocorticoid-dependent (e.g. alpha 2-acute phase globulin, haptoglobin) and -independent fashion (alpha 1-acute phase globulin), respectively. It can be concluded that glucocorticoids, catecholamines as well as cytokines are the main candidates for triggering the acute phase response; however, additional factors may also be of importance.

Adrenalectomy↗
PubMed1986

Glucose tolerance tests and "in vivo" response to intravenous insulin in the unanaesthesized late pregnant rat and their consequences to the fetus.

In the late pregnant rat, blood glucose levels were lower and plasma RIA-insulin levels were slightly higher than in virgin animals. Oral and intravenous glucose tolerance tests produced parallel changes in blood glucose in both groups whereas plasma RIA-insulin increased more in the pregnant animals. Blood glucose levels after either low (0.1-1 IU/kg) or high (10 IU/Kg) doses of intravenous insulin decreased more slowly and less in pregnant than in virgin rats. Fetal blood glucose levels were not affected by maternal insulin treatment. Results show that in the unanaesthesized late pregnant rat both insulin sensitivity and responsiveness decreased and it is proposed that this insulin resistance may represent a mechanism to delay disposal of ingested nutrients by maternal tissues, ensuring their availability to the fetus.

Animals↗
PubMed1986

Ultrastructure of Leydig cells in human ageing testes.

Ultrastructural study of Leydig cells in elderly men revealed the following Leydig cell types: (1) ultrastructurally normal Leydig cells (46.2%); (2) Leydig cells either with multiple cytoplasmic or intranuclear Reinke crystals or with numerous para-crystalline inclusions (6.1%); (3) multivacuolated Leydig cells with the cytoplasm almost filled by lipid droplets (16.7%; (4) dedifferentiated Leydig cells with poor development of agranular endoplasmic reticulum and mitochondria, and increased amounts of lipofuscin granules (22.3%); and (5) bi- or trinucleate Leydig cells (8.7%) showing either a normal (2.8%) or dedifferentiated (5.9%) cytoplasm. These results suggest an involution of Leydig cells with advancing age. A correlation between the proportion of altered Leydig cells and the decrease in testosterone and increase in luteinising hormone levels could be observed.

Adult↗
PubMed1986

[Sterility of tubal origin: microsurgery and fertilization in vitro].

Thanks to recent advances, in-vitro fertilization should alter the clinical indications in cases of sterility due to tubar obstruction. In this article, the authors compare two groups of patients: one group of 109 women treated by means of in-vitro fertilization and another group of 117, treated by microsurgery. In tubar sterility, IVF achieved a 16% pregnancy rate per attempt. In the case of microsurgery, the actuarial rates were calculated (Kaplan Meier method) from a prognostic score. It was found that in the group of women with a "good score", tubar surgery gave results which could be achieved only after 3 or 4 attempts at IVF. On the other hand, in the "poor prognosis" group, IVF was better than microsurgery after a single attempt. Clinical teams should, therefore, reconsider the indications for tubar surgery in the light of the indications for in-vitro fertilization.

Embryo Transfer↗
PubMed1986

Casualty and surgical services in Perthshire general practitioner hospitals 1954-84.

The results are reported of a study of casualty and surgical services in five general practitioner hospitals in Perthshire - Aberfeldy, Auchterarder, Blairgowrie, Crieff and Pitlochry. Details of the total workload, the nature of the conditions treated and the referral rate to major hospitals are given. Figures for the Royal Infirmary, Perth, the main referral hospital for the county, are also given for comparison. The surgical service at one of the rural hospitals is described.Experience has demonstrated the usefulness of these hospitals in providing casualty and surgical services to both the local population and to visitors, and their superiority in providing these services over health centres because staff and beds are available 24 hours a day.Rural general practitioner hospitals merit a continuing share of resources and bed allocation as they spare major hospitals surgical and medical work. The general practitioners serving the hospitals studied here undertook almost 40% of the total accident and emergency workload in the Perth and Kinross area of Scotland.

Adolescent↗
PubMed1985

Regulation of the translocation of phosphatidate phosphohydrolase between the cytosol and the endoplasmic reticulum of rat liver. Effects of unsaturated fatty acids, spermine, nucleotides, albumin and chlorpromazine.

The translocation of phosphatidate phosphohydrolase between the cytosol and the microsomal membranes was investigated by using a cell-free system from rat liver. Linoleate, alpha-linolenate, arachidonate and eicosapentenoate promoted the translocation to membranes with a similar potency to that of oleate. The phosphohydrolase that associated with the membranes in the presence of [14C]oleate or 1mM-spermine coincided on Percoll gradients with the peak of rotenone-insensitive NADH-cytochrome c reductase, and in the former case with a peak of 14C. Microsomal membranes were enriched with the phosphohydrolase activity by incubation with [14C]oleate or spermine and then incubated with albumin. The phosphohydrolase activity was displaced from the membranes by albumin, and this paralleled the removal of [14C]oleate from the membranes when this acid was present. Chlorpromazine also displaced phosphatidate phosphohydrolase from the membranes, but it did not displace [14C]oleate. The effects of spermine in promoting the association of the phosphohydrolase with the membranes was inhibited by ATP, GTP, CTP, AMP and phosphate. ATP at the same concentration did not antagonize the translocating effect of oleate. From these results and previous work, it was concluded that the binding of long-chain fatty acids and their CoA esters to the endoplasmic reticulum acts as a signal for more phosphatidate phosphohydrolase to associate with these membranes and thereby to enhance the synthesis of glycerolipids, especially triacylglycerol. The translocation of the phosphohydrolase probably depends on the increased negative charge on the membranes, which could also be donated by the accumulation of phosphatidate. Chlorpromazine could oppose the translocation by donating a positive charge to the membranes.

Animals↗
PubMed1985

Infrared spectroscopic study of the gel to liquid-crystal phase transition in live Acholeplasma laidlawii cells.

The temperature dependences of the infrared spectra of deuterium-labeled plasma membranes of live Acholeplasma laidlawii B cells and of the isolated plasma membranes demonstrate that the profiles of the gel to liquid-crystal phase transitions are very different. At temperatures within the range of the phase transition, the live mycoplasma is able to keep the "fluidity" of its plasma membrane at a much higher value than that of the isolated plasma membrane at the same temperature. The difference is particularly pronounced at and around the temperature of growth. Live Acholeplasma laidlawii, grown at 37 degrees C on a fatty acid depleted medium supplemented with myristic acid (C14:0), pentadecanoic acid (C15:0), or palmitic acid (C16:0), are highly "fluid"; i.e., at the temperature of growth, the fractional population of the liquid-crystalline phase is 95-100% at 37 degrees C, whereas in the case of the isolated plasma membranes the fractional population of the liquid-crystalline phase at 37 degrees C is only 58% (C14:0), 36% (C15:0), or 38% (C16:0).

Acholeplasma laidlawii↗
PubMed1985

Neutron brachytherapy is better than conventional radiotherapy in advanced cervical cancer.

Californium-252 (252Cf), a fast-neutron emitting radioisotope, was used for neutron brachytherapy (NT) of 82 patients with advanced (stage III and IV) cervical cancer. The results were compared with caesium-137 brachytherapy; both isotopes were given in combination with high-dose fractionated pelvic radiotherapy. In patients with stage IIIB disease (ie, tumour to the pelvic side-wall), 252Cf intracavitary therapy resulted in 54% 5-year survival compared with 12% in the caesium group. To be effective, Cf-NT must be given before external beam (photon) therapy.

Actuarial Analysis↗
PubMed1985

Extended Hildebrand solubility approach: sulfonamides in binary and ternary solvents.

The extended Hildebrand solubility approach is used to estimate the solubility of sulfonamides in binary and ternary solvent systems. The solubility of sulfisomidine in the binary solvent, dioxane-water, shows a bell-shaped profile with a solubility maximum well above the ideal solubility of the drug. This is attributed to solvation of the drug with the dioxane-water solvent, and indicates that the solute-solvent interaction energy (W) is larger than the geometric mean (delta 1 delta 2) of regular solution theory. The solubilities of sulfadiazine, sulfisomidine, sulfathiazole, and sulfamethoxazole were determined in mixtures of dimethylacetamide, glycerol, and water, and the solubility profiles were well reproduced by use of the extended Hildebrand solubility approach. Since the solubility parameter (delta 1 = 11) of the solvent (dimethylacetamide) was approximately equal to the solubility parameters of the sulfonamides, and because of the powerful solvating power of dimethylacetamide, the solubility profiles did not exhibit peaks as observed for sulfisomidine in dioxane-water. When sulfisomidine was dissolved in a ternary mixture, i.e., butyl acetate (delta 1 = 8.5), dimethylacetamide (delta 1 congruent to 11), and methanol (delta 1 = 14.5), a spike was produced in the solubility profile at the solubility parameter of dimethylacetamide. This sharply peaked profile suggests that the two branches be treated as separate solubility curves, which are then independently well reproduced by the extended Hildebrand solubility approach. None of the four sulfonamides yielded log-linear relationships in the ternary mixtures.

Acetamides↗
PubMed1985

Dependence of solute solubility parameters on solvent polarity.

In nonpolar solvents a solute may self-associate through polar interactions, exposing its nonpolar surface to a solvent with a low solubility parameter, delta 1. In polar solvents a solute is solvated, presumably, by the polar groups of the solvent. This "chameleonic" effect results in different solubility parameters for a solute, depending on the polarity of the solvent. This report presents data for solute solubility parameters in solvents of variable polarity and gives suggestions for dealing with the chameleonic effect associated with solute-solvent interaction.

Benzoates↗
PubMed1985

Residuals in multiple regression analysis.

An examination of residuals can be used as a technique to determine the best model for use in multiple-regression analysis. In addition to R2 and the Fisher F ratio, a complete analysis of residuals has been used by statisticians for many years to estimate bias and to choose the best equation to fit physicochemical as well as biological and psychosociological data. However, residual analysis has seldom appeared in studies in pharmaceutics, pharmacology, or medicinal chemistry. This report gives two examples to show the usefulness of residual analysis in the pharmaceutical sciences.

Aminopyridines↗