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Biomedical subjects

H Morris

Publications and source records attributed to H Morris.

At least 109 records · Page 6Linked to original sources
PubMed1981

An assessment of radioimmunoassay procedures for determination of anti-acetylcholine receptor antibodies in the sera of patients with myasthenia gravis.

A reproducible radioimmunoassay procedure for the determination of anti-acetylcholine receptor antibodies in the sera of patients with myasthenia gravis is described and examined in detail. The assay combines features of a number of methods previously outlined and allows repeat determinations of antibody titre in a given myasthenic serum sample with coefficient of variation 6%. The mean +/- standard deviation for normal human serum anti-acetylcholine receptor antibodies was found by this procedure to be 0.024 +/- 0.033 nmol/l alpha-bungarotoxin binding sites whereas the range for myasthenic patients was 0-139.14 nmol/l with a mean value of 7.55 nmol/l alpha-bungarotoxin binding sites.

Acetylcholine↗
PubMed1979

Sicklers surviving childhood in Tanzania.

Sixty two cases of sickling haemoglobinopathy have been admitted and specially studied between 1973 and 1977 in the Bugando Hospital, Mwanza, Tanzania. Presenting symptoms are described. The problems of recognition in the medical diaspora and of management are considered. It is expected that with improving regional health facilities more cases will survive childhood but also will cause special difficulties in adequate care. It is pleaded that because of the ubiquity of the HbS gene in Tanzania sufficient priority is given to the affected in planning health services in Tanzania.

Adolescent↗
PubMed1978

Human leucocyte antigens and mixed lymphocyte reaction in severe pre-eclampsia.

Human leucocyte antigens (HLA) and mixed lymphocyte reactions (MLR) were studied in 38 women with severe pre-eclampsia and their husbands. Thirty-nine women with normal pregnancies and their husbands served as controls. Thirty-three of the control women were matched for age and parity with members of the study group. Infants were studied when possible. HLA compatibility was increased in the pre-eclamptic group compared with matched controls and with theoretical estimates for possible matings. The one-way MLR at delivery showed diminished response of maternal to paternal and cord cells in pre-eclamptic women. This reduced maternal reactivity in women with pre-eclampsia may have a role in the illness, and paternal/maternal histocompatibility may be a feature of the severe form.

Female↗
PubMed1976

Stress distribution within circumferential clasp arms.

An analysis of stress distributions within circumferential clasp arms with various tapers, was undertaken in an effort to (1) determine the area of maximum stress concentration in both tapered and non-tapered clasps, and (2) to compare this point of maximum stress concentration with the area of frequent clasp breakage. The non-tapered clasp showed better distribution of stresses than the tapered clasps. The less favourable stress concentrations could result in eventual failure of the clasp when coupled with other factors such as porosities. The maximum shear stresses in the non-tapered clasp also were lower than those in the tapered clasps. As the taper of the clasp became more accentuated, the magnitude of the stresses increased and shifted towards the tip of the clasp. The maximum tensile stress calculated in a replica of a chromium-cobalt-nickel clasp was in the order of 34 MN/m2 which is well below the ultimate tensile strength of the alloy. This observation leads to the proposal that failure of clasps is a function not only of design but also of other variables, such as porosities, surface irregularities, and fatigue.

Dental Stress Analysis↗
PubMed1976

Enhancement of tumor growth following immunization with Bacillus Calmette-Guérin cell walls.

The effect of preimmunization with Bacillus Calmette-Guerin cell walls (BCGcw) on tumor growth was studied with the use of transplantable Morris Hepatoma 3924a in inbred ACl rats. There was an increase in tumor incidence, an increase in the i.m. tumor growth rate, and an increase in the average i.m. tumor mass in animals that were preimmunized with BCGcw. The BCGcw-induced enhancement in tumor growth was dependent upon the amount of tumor present at the time of BCGcw immunization. No enhancement occurred in animals immunized with BCGcw 12 days after the inoculation of tumor cells.

Animals↗
PubMed1974

Pleiotropic effects of mutations involved in the regulation of Escherichia coli K-12 alkaline phosphatase.

Induction of alkaline phosphatase in wild-type Escherichia coli K-12 leads to the appearance of three new proteins in addition to alkaline phosphatase in the periplasmic space of the bacteria. These proteins are detected in autoradiograms of sodium dodecyl sulfate-acrylamide gel electropherograms of extracts from cells labeled with [(35)S]methionine. Studies with constitutive mutants defective in the three genes phoS, phoT, and phoR that have been shown to regulate alkaline phosphatase synthesis indicate that the three periplasmic proteins are coregulated with alkaline phosphatase. A mutant that has a deletion in the alkaline phosphatase structural gene phoA produces the three proteins, but a newly discovered mutant phoB that has a defect in the expression of alkaline phosphatase fails to produce the three proteins. phoB mutants are shown here to be unable to make detectable amounts of alkaline phosphatase polypeptides, as measured by immunoprecipitins or acrylamide gel electropherograms. On the basis of these results we suggest a new model for the regulation of alkaline phosphatase biosynthesis. In this model, a ternary complex composed of phoB(+) and phoR(+) gene products and an internal metabolite functions as a positive control element to regulate the transcription of several cistrons coding for periplasmic proteins.

Alkaline Phosphatase↗
PubMed1972

Effects of proline analogues on the formation of alkaline phosphatase in Escherichia coli.

Two of the four proline analogues tested for their effect on the formation and activity of Escherichia coli alkaline phosphatase were able to substitute for proline in protein synthesis in a proline auxotroph. One of these, 3,4-dehydroproline, effectively replaced proline and led to formation of an active enzyme under conditions where no proline was present in the polypeptides. Substitution of azetidine-2-carboxylate for proline prevented active enzyme formation, producing instead altered monomeric forms of the alkaline phosphatase. These were detected with antibodies specific to denatured forms of the enzyme, and they were also characterized, together with cellular proteins, by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Alkaline phosphatase, as well as several other proteins, is localized exterior to the bacterial cell cytoplasm in the periplasmic space. In the presence of azetidine-2-carboxylate, a substantial number of these periplasmic proteins retain their specific site of localization, and the denatured subunits of alkaline phosphatase were only detected in the periplasmic fraction of the cell. Thus, secretion of these proteins does not appear to require a high degree of specificity in the native structure of the polypeptide chain. The analogues 4-allohydroxyproline and 4-thiazolidine carboxylate were unable to substitute for proline in protein synthesis but they inhibited growth of E. coli.

Alkaline Phosphatase↗