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E Stewart

Publications and source records attributed to E Stewart.

At least 73 records · Page 4Linked to original sources
PubMed1980

Host immune status in uraemia. I. Cell-mediated immune mechanisms.

An experimental model of stable uraemia has been used to determine the effect of uraemia on cell-mediated immune mechanisms in the rat. Controlled resection of renal tissue allowed the establishment of a 'moderate' (blood urea 100-200 mg/100 ml) and 'severe' grade of uraemia (BU > 200 mg/100 ml). The immune responsiveness of isolated lymphocyte suspensions from uraemic animals was similar to that of sham-operated animals but lymphocyte function in both groups was suppressed compared with control non-manipulated animals. This was particularly evident in the graft vs host reaction. The host vs graft which assumes the cell-mediated immune status in the live animals, was also depressed in the uraemic animals but in contrast to the previous results sham-operated animals exhibited normal responses. The results underscore the importance of surgically induced anergy as a factor complicating the assessment of immune function in uraemia and may explain some of the inconsistencies observed in the evaluation of cell-mediated immunity by in vitro analysis of lymphocyte suspensions and tests of immune function in the intact host.

Animals↗
PubMed1980

Host immune status in uraemia. II. Serum factors and lymphocyte transformation.

A model of experimentally induced uraemia has been used to study the effect of serum from uraemic rats on the immune responsiveness of thymus-derived (T) lymphocytes. Splenic lymphocytes from normal or uraemic animals responded to mitogenic stimulation with concanavalin A to a similar degree when cultured in a tissue culture medium containing the maximum non-toxic concentration of normal or uraemic serum in the culture system (3%). Serum from uraemic animals, however, had an immunosuppressive effect if the serum was first dialysed for 24 hr before being added to the tissue culture medium. When an alternative vessel was used which allowed the concentration of serum in the medium to be increased to 10%, serum from severely uraemic animals markedly suppressed the capacity of lymphocytes from normal animals to respond to Con A. Thus while serum from uraemic animals can be shown to be immunosuppressive, the results of the experiments are influenced by the conditions in vitro. The type of culture vessel and the concentration of serum in the culture medium are particularly critical determinants. It is likely that variations in laboratory procedures have contributed to the differences of opinion on the effect of serum from uraemic individuals on lymphocyte function.

Animals↗
PubMed1979

B lymphocyte colony formation in renal infection.

The effect of renal infection on B lymphocyte colony formation has been investigated in the belief that a study of the effect of infection on subpopulations of lymphoid cells might provide direct evidence of the effect of infection on the immmune system. Renal infection was induced in mice, and the specific immune response of the B lymphocyte compartment was quantitated by determining the serum antibody and plaque-forming cell response to infection. Under the conditions of the experiment, the ability of splenic lymphocytes to form B lymphocyte colonies was significantly depressed during the first 7 days of infection, and the results suggest that a study of the responses of lymphoid cells to infection may provide information of diagnostic and prognostic value.

Animals↗
PubMed1978

Artificial capillary perfusion cell culture: metabolic studies.

Glucose, lactic-acid, and oxygen metabolism of BHK and L929 cells on artificial capillary perfusion units have been studied using several different modes of perfusion. After 7 to 10 days, cells planted in the extracapillary compartment of culture units containing 80 to 150 fibers reached populations that used 0.073 +/- 0.025 mumol per min glucose and 0.76 +/- 0.26 microliter per min oxygen and excreted 0.078 +/- 0.038 mumol per min lactic acid. From these data it is estimated that these units contain approximately 2 x 10(7) cells. The metabolic rate of cultures perfused through the capillaries or through the extracapillary compartment was not affected significantly by change in flow rate except at perfusion flow rates less than or equal to 0.05 ml per min. The cell population, as measured by metabolic activity, did not increase significantly when the serum content of the medium was less than or equal to 1%. No major differences were found in glucose utilization rates of equal numbers of cells on artificial capillaries, on short-term suspension culture, or as monolayers in plastic flasks. Artificial capillary perfusion may provide a simple system for studying metabolism of mammalian cells in culture.

Cell Count↗
PubMed1978

Modification by suppressor cells and serum factors of the cell-mediated immune response in experimental pyelonephritis.

A marked suppression of the thymusderived (T)-lymphocyte response to concanavalin A has been demonstrated in vitro during renal infection. Suppression of the T-lymphocyte response in vitro was seen as early as 2 h after the induction of renal infection, but maximum suppression was found 24-72 h later. A population of suppressor cells in the splenic lymphocyte population, generated during the host's response to infection, contributed to the depressed lymphocyte response. Removal of suppressor cells restored the mitogenic responsiveness of the remaining splenic lymphocytes. Conversely, in co-culture experiments, a suppressor cell present in the splenic lymphocyte population of pyelonephritic animals was shown to be capable of suppressing the mitogenic responsiveness of normal splenic lymphocytes. Significantly reduced host vs. graft responses by the pyelonephritic animals confirmed, in vivo, the depression of cell-mediated immune mechanisms. An additional suppressive factor was found in the serum of pyelonephritic animals which depressed in vitro the mitogenic responsiveness of splenic lymphocytes from normal animals. Support for the suppressive role of this serum factor was found when splenic lymphocytes from pyelonephritic animals were tested in vivo in the absence of homolgous serum (graft vs. host). Under these conditions, the lymphocytes showed an enhanced reaction compared with lymphocytes from normal animals. The presence of a suppressor cell population and a serum factor, both capable of depressing cell-mediated mechanisms, may be major factors contributing to the establishment of infection in the kidney.

Animals↗
PubMed1978

99m technetium sulphur colloid localization in renal infection. An experimental evaluation.

Renal uptake of 99mTechnetium sulphur colloid (99mTcSC) was investigated in 99 animals with experimentally induced unilateral pyelonephritis and in 60 animals with a thermally induced renal injury. The degree of localization of 99mTcSC in the kidney was determined by direct counting of retained isotope after bilateral nephrectomy at autopsy. Phagocytosis of 99mTcSC by inflammatory tissue has been reported and it was anticipated that renal infection would lead to an increase in 99mTcSC uptake by the kidney. In fact it was found that renal infection with pathologic changes resulted in a significant decrease in the localization of 99mTcSC in the pyelonephritic kidney. A similar decrease was found in the thermally injured kidney but renal infection without pathologic changes did not give rise to any changes in radionuclide uptake. These findings suggested that phagocytosis by the proximal convoluted tubular cells is the normal mechanism for 99mTcSC accumulation in the kidney and that renal infection reduced the phagocytic capability of these cells.

Animals↗
PubMed1976

Cosmetic caliper for use with flail leg.

A new type of long leg brace made of polypropylene with an internal shoe foot piece seems to offer distinct advantages over the older, conventional type of calipers.

Braces↗
PubMed1976

Experimental pyelonephritis: the effect of chronic active pyelonephritis on renal function.

In these experiments, renal function in chronic active pyelonephritis was investigated and the effect of antibiotic treatment and elimination of infection on the gross pathology, histopathology and renal function in animals with chronic pyelonephritis was determined. A severe loss of urine concentrating capacity was demonstrable when the maximum urinary osmolality of a group of animals with pyelonephritis was compared with control animals. Concentrating capacity decreased sharply over the first month but further loss over an eight-month period was minimal. A compensatory increase in the glomerular filtration rate (GFR) in the control, nonchallenged, group occurred after nephrectomy but no comparable compensation in the infected group was found. Antibiotic therapy had a marked effect on the urinary concentrating capacity and the defect in concentrating ability was significantly less in the treated animals during the first 30 days after challenge. Infection again prevented a compensatory increase in the GFR of pyelonephritic animals which was not reversed by antibiotic therapy. Blood urea concentrations in treated and nontreated animals were not significantly different nor did the eradication of infection affect the gross pathologic and histopathologic changes found at autopsy.

Animals↗
PubMed1975

Type C oncornavirus isolation studies in systemic lupus erythematosus. I. Attempted detection by isopycnic sedimentation of 3H-uridine-labelled virions.

Type C oncornavirus isolation was attempted from cell cultures of tissues from 7 patients with systemic lupus erythematosus. Detection was based on the characteristic sedimentation of 3H-uridine-labelled virions at a density of 1-16 g/ml. Cultures positive by this method were negative by two other criteria for type C viruses: characteristic virions by electron microscopy and the viral enzyme RNA-directed DNA polymerase. The positive results were probably due to cellular damage by prolonged radiolabelling, with release of organelles containing labelled RNA sedimenting at the same density as type C viruses.

Cells, Cultured↗
PubMed1975

Nursing in India.

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Education, Nursing↗