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Biomedical subjects

C McCombs

Publications and source records attributed to C McCombs.

11 recordsLinked to original sources

The effects of microwaves on airborne microorganisms.

This paper reports preliminary results of simple experiments carried out to study the effects of microwave irradiation at 2.45 GHz on fungi, yeast and bacteria of the type encountered in food processing plants or in enclosures containing individuals infected with tuberculosis mycobacterium (TB). The results are sufficiently encouraging to justify further multivariable experiments particularly with air circulation schemes in which the air can be sterilized in a circular cylindrical microwave cavity operating at a higher order mode.

Air Pollution↗

Potential of the monoglyceride and triglyceride of DL-3-hydroxybutyrate for parenteral nutrition: synthesis and preliminary biological testing in the rat.

Esters of short-chain organic acids have shown some promise as potential nutrients for parenteral feeding. Most glycerols are water insoluble but those of the ketone bodies have some water solubility. Of interest is that the triacylglycerol of 3-hydroxybutyrate has water solubility while the triacylglycerol of acetoacetate does not. The mono- and triacylglycerol of DL-3-hydroxybutrate were synthesized and tested for toxicity and nutritional value as parenteral nutrients. Both compounds have an estimated energy density of 19.7 kJ/g (4.7 kcal/g) and are water soluble. The compounds were infused into rats for 7 d at a rate to provide 113 kJ/d and were accompanied by a low-energy oral diet. Control, pair-fed rats were infused with isocaloric glucose or 0.9% saline. Nitrogen intake, output, and balance, body weight changes, and liver size were compared. The two glycerols of 3-hydroxybutyrate supported similar nitrogen retention, body weight changes, and liver size as found in the pair-fed control animals infused with glucose. Rats infused with saline retained less nitrogen, had decreased body weight, and had smaller livers. The data demonstrated that the glycerols of DL-3-hydroxybutyrate are not toxic, provide metabolic energy when infused intravenously, and could be used as nutrients for parenteral feeding.

3-Hydroxybutyric Acid↗

Mechanism of a lymphocyte abnormality associated with HLA-B8/DR3: role of interleukin-1.

Lymphocytes from normal individuals with the histocompatibility antigens HLA-B8 and DR3 have impaired proliferative responses when stimulated with suboptimal concentrations of mitogens. We have previously shown that an important factor in the impaired response is a failure to produce normal quantities of interleukin-2 (IL-2). To examine the mechanism of decreased responsiveness further, we measured interleukin-1 (IL-1) production of low responder subjects compared with controls. The peripheral blood mononuclear cells of five low responder individuals with HLA-B8/DR3 stimulated with 0.05 micrograms/ml of phytohaemagglutinin (PHA) accumulated only 0.036 U/ml of IL-1 compared with 0.32 U/ml for normal responders. There was a highly significant correlation between the PHA-stimulated IL-1 concentration at 12 h and the subsequent IL-2 concentration at 48 h(r = 0.89, P less than 0.0001) suggesting a role of decreased IL-1 production in the impaired response. A study of unfractionated or column-fractionated culture supernatants revealed no evidence that the decreased IL-1 activity in the supernatants of low responder subjects was related to increased IL-1 inhibitor concentrations. These results suggest that impaired IL-2 production and lymphocyte proliferation in healthy subjects with HLA-B8/DR3 may be mediated at least in part by decreased IL-1 production, and implicates a defect of a very early event in lymphocyte activation.

Adult↗

Reversible melphalan-induced lung damage.

Pulmonary toxicity occurs after the administration of several different chemotherapeutic agents. Pulmonary toxicity due to melphalan alone has not been documented. In the patient we describe respiratory symptoms and pulmonary infiltrates developed twice within two weeks of the second course of a monthly melphalan and prednisone regimen. Open lung biopsy revealed interstitial pneumonitis. The infiltrates cleared on both occasions when melphalan was withheld. Special studies performed seven weeks after the last dose of melphalan had been given revealed that the patient's alveolar macrophages suppressed phytohemagglutinin induced blastogenesis of his peripheral lymphocytes. Melphalan itself did not stimulate the blastogenesis of the peripheral lymphocytes. Melphalan should be added to the list of therapeutic agents that induce pulmonary disease. However, the pathogenesis of the disease remains to be elucidated.

Aged↗

Levamisole maintains cyclophsophamide-induced remission in murine lupus erythematosus.

Antibodies to DNA in 14 month old male NZB/W F1 mice were markedly decreased after 4 weeks of cyclophosphamide therapy. A group of these mice and untreated controls subsequently received levamisole for 12 weeks. Antibodies to DNA returned to pretreatment levels within 8 weeks in animals receiving only cyclophosphamide, whereas levamisole treatment after cyclophosphamide delayed the reappearance of these antibodies. Glomerular immunoglobulin deposition and the degree of lymphocytic tissue infiltrate were decreased in animals receiving cyclophosphamide followed by levamisole as compared with non-treated control animals or those receiving cyclophosphamide or levamisole alone. In vitro T-cell mitogen reactivity was inversely correlated with the final DNA antibody titres of individual mice, suggesting a relationship between decreased autoantibody production and augmented cellular immunity. We discuss possible mechanisms by which levamisole may delay the reappearance of autoantibodies and decrease the histological evidence of lupus nephritis when given to New Zealand mice first treated with cyclophosphamide.

Animals↗

Decreased lymphocyte reactivity to a suboptimal concentration of phytohemagglutinin in Sjögren's syndrome.

Significantly decreased lymphocyte reactivity to a suboptimal concentration of phytohemagglutinin (PHA) was found in patients with Sjögren's syndrome (SS), whereas the response to an optimal concentration was generally normal. Kinetic studies were performed on control lymphocytes. Only suboptimal PHA concentrations stimulated tritiated thymidine (3H-TdR) incorporation in proportion to the number of potentially reactive lymphocytes. Kinetic studies of SS patients suggested that their low reactivity was attributable to fewer functionally reactive lymphocytes rather than to a decreased rate of proliferation.

Adolescent↗

Functional deficiency of splenic adherent cells in New Zealand black mice.

New Zealand Black (NZB) mice hyporespond after in vitro immunization to sheep erythrocytes but not after in vivo immunization. The difference between in vitro and in vivo immunization was found to involve a non-antigen-specific change in the spleen which occurs in vivo soon after priming. Adherent spleen cells from young NZB or control strain mice were compared in their ability to cooperate with nonadherent cells in the induction of a primary immune response to sheep erythrocytes in vitro. The results support the hypothesis that there is a functional deficiency of adherent cells in the spleens of unprimed NZB mice.

Animals↗