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Biomedical subjects

D S Nelson

Publications and source records attributed to D S Nelson.

At least 73 records · Page 4Linked to original sources
PubMed1982

Effects of tumour cell culture supernatants on some biochemical activities of macrophages.

The following enzyme activities were measured in cell lysates and supernatants from mouse peritoneal macrophages incubated with products of cultured tumour and other cells: acid phosphatase, beta-D-glucuronidase, N-acetyl-D-glucosaminidase, muramidase (lysozyme), lactic dehydrogenase (supernatant only) and plasminogen activator (supernatant only). There were no noteworthy changes in enzyme activities. Hydrogen peroxide production by appropriately stimulated mouse and/or guinea-pig peritoneal exudate macrophages was variably inhibited by supernatants from some tumour cells and some normal cells. Changes in these biochemical activities of macrophages do not appear to be closely related to the anti-inflammatory activity of tumour cell products.

Animals↗
PubMed1982

Development of extender and techniques for frozen turkey semen. 1. Development.

An extender for turkey semen with a frozen-thawed recovery of greater than or equal to 50% motile spermatozoa and a vigorous swirl was developed. The effect of glucose, a comparison of 10 different sugars in the extender, the use of sodium acetate and potassium acetate, the ratio of dimethylsulfoxide to ethylene glycol, the percent total cryoprotectant, equilibration time, and osmotic pressure were all tested. Replacement of approximately half of the extender with an iso-osmolar glucose solution yielded higher percentages of motile spermatozoa with both fresh and frozen-thawed semen samples. Replacement of glucose with other carbohydrates did not enhance recovery of frozen-thawed semen. The proportion of sodium and potassium acetates to TESNaK2 in the extender had no effect on motility. Approximately equal proportions of ethylene glycol to dimethylsulfoxide, with a final concentration of 11.2% after dilution, produced at or near optimal recovery of spermatozoal motility after freezing. Twenty to 90 min equilibration times before freezing yielded significantly higher recovery of motile sperm postthaw than shorter periods. A wide range of extender osmotic pressures were compatible with recovery of spermatozoal motility postthaw. The final extender consisted of 4.70 g sodium acetate, 3.39 g potassium acetate 9.23 g TES, .353 g sodium hydroxide, .492 g potassium hydroxide, 32.00 g glucose, H2O q.s. 1000 ml, 370 mOsm/kg, pH 7.2. Ethylene glycol and dimethylsulfoxide were added (1:1 ratio) for a final concentration of 11.2% cryoprotectant after dilution. Semen was held undiluted for 6 min, extended 1:4 at 22 C, and equilibrated for 30 min at 0 C before pellet freezing.

Animals↗
PubMed1982

Development of extender and techniques for frozen turkey semen. 2. Fertility trials.

The effects of cryoprotectant concentrations, redilution, centrifugation, and dialysis techniques on fertility of fresh and frozen-thawed turkey semen were tested. Fresh extended semen with final concentrations of 4.8, 5.6, 9.6, and 11.2% cryoprotectant (dimethylsulfoxide and ethylene glycol, 1:1 ratio) showed a significant (P less than .05) decrease in fertility when compared to semen without cryoprotectant. Fertility of fresh semen extended with 4.8% cryoprotectant when centrifuged or rediluted and centrifuged, was unaffected when compared to cryoprotectant treated semen. Fertility of frozen-thawed semen after redilution and centrifugation was low, but samples rediluted one part semen for two parts extender yielded significantly (P less than .05) higher fertility than semen rediluted 1:1. Fresh semen extended with 11.2% cryoprotectant showed a highly significant (P less than .01) decrease in fertility despite dialysis, while semen with 9.6% cryoprotectant showed no difference when compared to dialyzed semen without cryoprotectant. Fertility of frozen-thawed semen dialyzed against blood plasma (approximately pH 7.9) and blood plasma adjusted with TES2 to pH 7.4 or pH 7.2 was not significantly different. Fertility of frozen-thawed semen dialyzed for 30 min was significantly higher (P less than .01) than semen dialyzed for 15 min or 0 min. Frozen-thawed semen dialyzed with a semen to dialysate ratio of 1:15 and 1:24 supported significantly higher (P less than .01) fertility than at 1:50 ratio. The AGPT3 dialysate yielded significantly higher (P less than .01) fertility than blood plasma adjusted to pH 7.2 with TES.

Animals↗
PubMed1982

Inhibition of cytokine production by a tumor cell product.

Supernatants from cultured mouse and human tumour cells, but not mouse or guinea-pig fibroblasts, inhibited the production of a lymphokine, macrophage chemotactic factor, by PHA-stimulated mouse spleen cells. The supernatants affected spleen cells from old, but not young, mice. They were most active if added at the start of the spleen cell culture and did not act by binding phytohaemagglutinin (PHA). The active material had an approximate molecular weight, on membrane filtration, of 1000-10,000 and could be bound to and eluted from Con A-Sepharose. Tumour supernatant factor(s) of similar molecular weight inhibited the production of interleukin 1 (lymphocyte activating factor) in response to lipopolysaccharide by stimulated thioglycollate-induced peritoneal exudate macrophages, but not by Corynebacterium parvum-activated macrophages. Similar tumour-produced material has been found to inhibit the early phase of delayed-type hypersensitivity reactions in older mice. It is suggested that this effect is due, at least in part, to inhibition of interleukin 1 production leading to inhibition of lymphokine production.

Age Factors↗
PubMed1982

IgE-dependent cellular adhesion and cytotoxicity to Litomosoides carinii microfilariae--nature of effector cells.

Albino rats immunized with sonicated microfilarial antigen incorporated in Freund's complete adjuvant, produce antibodies that promote cell-mediated adhesion and killing of Litomosoides carinii microfilariae in vitro. Using highly purified cell populations, it has been shown that macrophages and neutrophils are most active in this phenomenon. Eosinophils, while adhering readily to parasites in the presence of the antibody, did not affect the viability of the parasites when observed after 24 hr incubation.

Animals↗
PubMed1982

Macrophages and resistance of tumors 6. The effects of supernatants from cultures of normal and tumor cells on phagocytosis.

Mouse resident peritoneal macrophages were cultured with supernatants from cultures of tumor cells and normal cells, then tested for their capacity to phagocytose opsonized sheep erythrocytes (SRBC). Most tumor cells produced inhibitory material but some did not (HeLa, EL-4). Conversely, nonmalignant cells generally did not produce active material though some (Chang B cells) did. Inhibition was not noticeable until after 13 hr contact with tumor supernatant and then became progressively more pronounced at 24 and 48 hr. Phagocytic capacity recovered only partially on reincubation with fresh medium. Inhibition was caused by material of approximate M.W. less than 1,000 (by membrane filtration), which also inhibited macrophage migration in vitro but had no effect on delayed-type hypersensitivity reactions or tumor growth in vivo. There was no species specificity and normal macrophages from various sources were susceptible, although activated or stimulated macrophages were wholly or partly resistant. Tumor carriage was associated with an initial decrease in phagocytic capacity of resident peritoneal macrophages, followed by an increase then a second decrease, although the cells remained susceptible to the inhibitory effect of tumor supernatant in vitro. Depression of phagocytosis was more marked in the presence of normal mouse serum and less marked in the presence of human serum than in the presence of fetal calf serum. Phagocytosis of zymosan and pinocytosis of colloidal gold by mouse macrophages were also depressed by tumor cell products.

Animals↗
PubMed1981

Mechanism for nonspecific immunity of Listeria monocytogenes in rats mediated by platelets and the clotting system.

A proposed mechanism for nonspecific immunity to Listeria monocytogenes in rats based on the existence of an activatable lysin is described. Using a deoxyribonucleic acid release assay, we found lysin activity in serum made from whole blood but not in serum made from platelet-free plasma. Washed platelets and platelet lysates exhibited only partial activity as compared with that in serum. This activity was amplified by the addition of platelet-free plasma serum. The activity of the lysin was unaffected by heparin, dialysis, a serine esterase inhibitor, or heating to 56 degrees C for 30 min. Effective inhibitors were ethylenediaminetetraacetic acid and stronger heating (to 65 degrees C). Listeria organisms were found to reduce the recalcified clotting time to platelet-rich plasma in a dose-dependent fashion, indicating that the organisms can exhibit procoagulant activity. The susceptibility of rats to Listeria infection was enhanced by anticoagulant treatment. Rats were infected with Listeria organisms with and without administration of heparin. Heparin-treated rats developed bacteremia, and some died. None of the control rats developed bacteremia or died. These results suggest that natural immunity to Listeria infection is partly due to a platelet-dependent lysin which is activated during clotting and is, in turn, promoted by the Listeria organisms themselves.

Animals↗
PubMed1981

I. Tumor growth in mice with depressed capacity to mount inflammatory responses: possible role of macrophages.

Studies were made of the effects of various treatments on the growth in mouse feet of isografts of two methylcholanthrene-induced fibrosarcomas: C-4, of CBA/J mice, and A-2, of A/J mice. The isografts were prepared by pronase digestion of subcutaneous tumors and were injected as unseparated cell suspensions or as tumor-cell-enriched suspensions after depletion of infiltrating host inflammatory cells. The recipient mice were untreated or treated with reserpine, sublethal whole body irradiation, cyclophosphamide, or corticosteroids. Depletion of host cells from the inoculum resulted in increased growth from the same number of tumor cells. Reserpine treatment decreased the growth of both tumors, whether unseparated or tumor-cell-enriched, and whether injected into the foot or the flank. Irradiation, cyclophosphamide pretreatment, and corticosteroid pretreatment decreased the growth of normal inocula or enriched inocula or both. The effects of cyclophosphamide and corticosteroids were apparently not due to cytotoxicity to tumor cells. Normal resident peritoneal cells increased tritiated thymidine uptake by tumor cells in vitro. Sedimentation velocity separation showed the largest cells to be the most potent. It is suggested that some hot inflammatory reaction is necessary for optimal tumor growth and that murine hosts produce not only cells with antitumor effects but also cells, possibly a subpopulation of macrophages, that potentiate tumor growth.

Animals↗
PubMed1981

Antibody-dependent cell-mediated effects in bancroftian filariasis.

The nature of immunoglobulin and effector cells involved in the antibody-dependent cell-mediated adhesion and cytotoxicity to Wuchereria bancrofti larvae has been investigated. Human neutrophils and eosinophils purified from peripheral blood by metrizamide gradients readily adhered to the parasites in presence of IgG fraction of sera from majority of elephantiasis cases with amicrofilaraemia and many of the endemic normals. The cells from normal, microfilariae and elephantiasis cases were equally effective inthe adhesion reaction. While the adhered neutrophils killed the larvae, eosinophils were ineffective in this respect. DEC treatment of elephantiasis cases results in a significant reduction in the ability of their sera to promote cellular adhesion.

Antibody-Dependent Cell Cytotoxicity↗
PubMed1981

II. Tumor growth at sites of inflammation induced by mitogens in mice.

Experiments were carried out to determine whether the growth of tumors could be influenced by local inflammatory reactions induced by mitogens; Gram-negative bacterial lipopolysaccharide (LPS), concanavalin A (Con A) and phytohemagglutinin (PHA). Mice received injections, beneath the footpad or subcutaneously in the flank, of cells of syngeneic chemically induced fibrosarcomas with or without varying doses of mitogen. In the footpad (a) LPS caused a dose-dependent increase in the size; (b) Con A caused a decrease in the size of one of the three tumors, the decrease being inversely related to the dose of Con A; (c) PHA caused a dose-dependent decrease in the size of all three tumors: (d) PHA caused much smaller macroscopic inflammatory reactions than LPS or Con A. Subcutaneously injected tumor growth was inhibited by all three agents. Subcutaneous tumors contained a higher proportion of host inflammatory cells when mitogens had been mixed with the tumor inoculum. It is concluded that mitogens that can induce inflammatory reactions in mice can also bring about some suppression of tumor growth but that the depression is site-dependent and not clearly related to the apparent intensity of inflammation.

Animals↗
PubMed1981

Enhanced adhesion of rat neutrophils to Litomosoides carinii microfilariae in the presence of culture supernatants from mitogen-stimulated lymph node cells.

Microfilariae of the rat filarial parasite Litomosoides carinii are killed by normal rat neutrophils which adhere to them in the presence of antibody and complement. Adherence and killing were increased in the presence of the fluid from 48-hr cultures of Con A- or PHA-stimulated normal rat lymph node cells. Both normal and augmented binding were inhibited by cytochalasin B. The factor(s) responsible for increased binding was non-dialysable, susceptible to heat (56 degrees C, 30 min) and freezing and thawing. Its production was inhibited by cycloheximide. Pretreatment of neutrophils with stimulated culture supernatant for 3 hr, followed by washing, also augmented adherence. Similar pretreatment also enhanced phagocytosis of opsonized sheep erythrocytes and latex particles but did not increase candidacidal activity. These experiments suggest that cell-mediated immune reactions leading to lymphokine production may potentiate anti-filarial antibody-dependent cellular cytotoxicity and general phagocytosis by neutrophils.

Animals↗