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Biomedical subjects

R Ramasamy

Publications and source records attributed to R Ramasamy.

At least 127 records · Page 7Linked to original sources
PubMed1985

Double-beam flying spot scanner for two-dimensional polyacrylamide gel electrophoresis.

The construction of a double-beam photometer in which the light source is a cathode ray oscilloscope is described. The light spot from the oscilloscope was focused and reduced in size at the gel plane to give a diameter of less than 0.15 mm and make it possible to scan over a 50 X 59-mm rectangle; using reduced spatial resolution (spot less than 0.2 mm) the area scanned becomes 70 X 90 mm. The light from the CRT was divided into two beams; one was directed through the transparent object to a photomultiplier and the other to a reference photomultiplier. The signals from these two detectors were converted to the logarithm of the ratio by a logging amplifier to give a direct measure of absorbance. Positioning of the spot, control of light intensity, and measurement of absorbance were carried out through an interface to a 16-bit computer. The relationship between measured and actual absorbance was linear over the range of absorbance 0 to 2, which could be raised to 1 to 3 by placing a neutral filter in the reference beam. The system generated an image containing 256 X 256 pixels in about 5 min, the scanning speed was determined by the persistence time of the P4 phosphor on the cathode ray tube, and faster scans can be made using A6 phosphor.

Calibration↗
PubMed1985

Attempts to manipulate specific responses to induce resistance to Schistosoma mansoni in Kenyan baboons (Papio anubis).

Attempts were made to manipulate specific responses of baboons to protect them from infection with Schistosoma mansoni. In Experiment 1, eosinophilia was induced in naive baboons with Trichinella spiralis larvae given intravenously before intraperitoneal injection of globulin fractions from S. mansoni-infected baboon sera and subsequent percutaneous exposure to S. mansoni cercariae. In Experiment 2, baboons with 8- or 32-week-old primary S. mansoni infections received T. spiralis i.v. before an S. mansoni challenge. In experiments 3 to 5 respectively, naive baboons received intramuscularly before challenge: formalin-fixed S. mansoni schistosomula, with Bordetella pertussis as an adjuvant; a preparation of S. mansoni adult worm teguments; and a preparation of IgE-immune complexes obtained from S. mansoni-infected rat sera, with Freunds Complete Adjuvant. Minor, but statistically insignificant, protection was obtained in Experiments 2 (32-week infections) and 3, but was far less than that given by intact, irradiated living vaccines. There are signs on the horizon of non-living vaccines protecting rodents against S. mansoni infection and it would be prudent, as with drugs, to test these in primates before proceeding to man. The results of our experiments, though essentially negative, should help the design of any future vaccine trials in primates.

Animals↗
PubMed1985

A role for carbohydrate moieties in the immune response to malaria.

Treatment of antigen prepared from asexual blood stages of the human malarial parasite Plasmodium falciparum with a mixture of glycosidases resulted in a reduction in the ability of the antigen to bind antibodies from immune human and monkey sera in an ELISA assay. Some of the epitopes in the parasite material were heat stable, protease resistant, and sensitive to glycosidases. Proteins of Mr 110,000 and 65,000 from parasitized RBC were shown to have reduced antigenicity in Western blots after glycosidase treatment. The carbohydrate side chains of parasite glycoproteins therefore make a contribution to the total antigenicity of the parasite.

Adult↗
PubMed1983

Complement activation and fibrinolysis during infection with Theileria parva (East Coast fever) in cattle.

The role played by complement and fibrinolysis in the pathogenesis of pulmonary oedema and the disseminated, subendothelial, petechial haemorrhages in cattle infected with Theileria parva was investigated. There was a marked reduction in total haemolytic complement in animals that died of this disease whereas the survivors showed only transient changes. The reduction in C3 levels in animals with severe disease, however, was equivalent to that in the survivors. Neither circulating soluble immune complexes nor free antibody against macroschizonts were detected in sera from cattle with severe infection. In addition to the complement changes, high levels of fibrinogen degradation products (FDPs) were detected in sera from the infected animals. The rate of production of FDPs and reduction in total haemolytic complement paralleled the clinical course of the disease. It is, therefore, suggested that the pulmonary oedema and disseminated petechial haemorrhages seen in East Coast fever may be the direct result of the combined effects of complement activation and consumption of fibrinogen and fibrin.

Animals↗
PubMed1983

Unrecognised nocturnal hypoglycaemia masquerading as senile dementia.

A 70-year-old woman with insulin dependent diabetes mellitus presented with symptoms suggestive of senile dementia. Outpatient assessment failed to reveal poor diabetic control with frequent nocturnal hypoglycaemia. Eventual appreciation of the poor control resulted in several failed attempts at improving therapy with various subcutaneous insulin regimes. Intramuscular and intravenous routes produced acceptable blood glucose levels with striking reversal of the patient's symptoms. The possible causes of nocturnal hypoglycaemia in this patient are discussed.

Dementia↗