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Biomedical subjects

I R Tizard

Publications and source records attributed to I R Tizard.

At least 73 records · Page 4Linked to original sources
PubMed1976

The response to Trypanosoma congolense infection in calves. Determination of immunoglobulins igG1, igG2, igM and C3 levels and the complement fixing antibody titres during the course of infection.

Serum immunoglobulins, IgG1, IgG2, IgM and C3 levels and the complement fixing antibody titres were determined over a period of 15 to 18 weeks in 13 calves infected with Trypanosoma congolense. The mean IgM concentration increased from 2.88 mg/ml prior to infection to 23.75 mg/ml at the 3rd week after infection. This level dropped by the 5th week but elevated values of 13-19 mg/ml were maintained until the end of the experiment. The mean IgG1 level increased from 10.55 mg/ml to a peak of 26.90 mg/ml by 7 weeks. After the 10th week, levels remained in the range of 12-15 mg/ml. There was only slight increase in mean IgG2 after 7 weeks infection with the highest mean value of 17.09 mg/ml as compared to 10.70 mg/ml of control animals occurring at the 13th week. The mean C3 concentration decreased from 3.75 mg/ml to 0.95g/ml by 2 weeks and fluctuating low levels were maintained for the duration of the infection. The appearance of CF antibody, the decrease in C3 at about 1 to 2 weeks post infection and the subsequent drops in the CF titres and C3 at 5-6, 8 and 11 weeks were each coincident with the drops in packed cell volume.

Animals↗
PubMed1975

The dendritic cells of the guinea pig popliteal lymph node: identification and classification of cells observed by scanning electron microscopy.

Scanning electrom microscopy of guinea pig popliteal lymph nodes revealed that 3 types of cells adhered to glass and possessed extensive cytoplasmic processes. Two of these types were considered to represent extremes of a macrophage population on the basis of possession of surface receptors for cytophilic Abs, complement and immunoglobulin, as well as their distribution, quantity and morphology. The third cell type was characterized by possession of large numbers of filamentous dendritic processes. On the basis of morphology, quantity, distribution and the absence of receptors, this cell was considered to represent a cell type clearly distinct from the other cells observed in the normal lymph node.

Animals↗
PubMed1975

The effect of bacterial adjuvants on Trypanosoma lewisi infections in rats.

The effect of Escherichia coli endotoxin, B.C.G. vaccine and Bordetella pertussis vaccine on the parasitemia of Trypanosoma lewisi was studied in rats. It was found that in general, B. pertussis administration resulted in higher and more prolonged parasitemias than normal. In contrast E. coli endotoxin tended to reduce both the intensity and duration of parasitemia. Possible reasons for this phenomenon are discussed.

Adjuvants, Immunologic↗
PubMed1974

Cell-mediated hypersensitivity to Pasteurella hemolytica in normal and cold-stressed mice.

Mice infected with Pasteurella hemolytica developed cell-mediated hypersensitivity manifested by inhibition of macrophage migration but not by delayed skin reactions, to two antigen preparations from this organism. Relative to migration by the cells of uninfected animals, migration by cells from infected animals was inhibited to the same degree whether or not the animals were chilled. However, the cells from infected chilled animals were not able to migrate as far as the cells from normal mice even in the absence of antigen.

Animals↗
PubMed1971

Macrophage cytophilic antibody in mice: effect of bacterial lipopolysaccharide on the uptake of immunoglobulins by mouse peritoneal cells.

Injection of lipopolysaccharide from Escherichia coli intravenously into mice affected the ability of their peritoneal macrophages to adsorb antisheep erythrocyte cytophilic antibodies in vitro. After a single intravenous injection of lipopolysaccharide, the alteration in antibody uptake took the form of a triphasic response. An early evanescent increase in adsorptive capacity took place, which reached a maximum 5 min after injection and was followed immediately by a phase of depressed uptake of antibody. Enhancement of antibody uptake then increased to reach a maximum about 24 hr after injection, before declining slowly. The second enhancement phase was inhibited by prior immunization with E. coli or after multiple injections of lipopolysaccharide. Exposure of macrophages to lipopolysaccharide in vitro did not alter their capacity to take up cytophilic antibody. Changes in the capacity of macrophages and polymorphonuclear neutrophil leukocytes to adsorb opsonized erythrocytes were induced by injection of lipopolysaccharide and were similar to those induced with respect to the uptake of cytophilic antibodies by macrophages.

Journal Article↗