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Biomedical subjects

R R Watson

Publications and source records attributed to R R Watson.

At least 55 records · Page 3Linked to original sources
PubMed1996

Increased resistance to acetaminophen-induced hepatotoxicity in retrovirus-infected mice.

In this research we examined the influence of chronic retrovirus infection on the hepatic metabolism of a model substrate, acetaminophen (APAP), and its induced liver injury in mice inoculated with LP-BM5 murine leukemia viruses. Female C57BL/6 mice at 15-17 wks after LP-BM5 retrovirus inoculation and age-matched control animals were used in the studies. APAP treatment (300 mg kg-1, p.o.) resulted in moderate to severe centrilobular necrosis in control animals, with the necrotic area accounting for 40-60% of the total area. In contrast, the APAP-treated (300 mg kg-1, p.o.) infected animals exhibited mild zonal necrosis with the necrotic area accounting for 1-6% of the total area. In the same study, a statistically significant higher percentage of APAP glucuronide and a lower percentage of unchanged APAP were recovered from the urine of the LP-BM5-inoculated animals than from that of controls. No statistically significant differences between infected and uninfected animals in the urinary recovery of APAP sulfate, APAP cysteine, or APAP mercapturate were observed. The formation of APAP metabolites and APAP-associated biochemical changes were also determined from liver slice preparation to avoid in vivo complicating factors. Consistently more significant depletion of the intracellular glutathione levels and K+ content were observed in slices from the uninfected animals at high concentrations of APAP (1 and 2 mM) than in slices from the retrovirus-infected animals. The differences in APAP-associated biochemical changes were accompanied by a 1.4-1.5-fold increase in the formation of APAP glucuronide, sulfate, and glutathione metabolites in slices prepared from animals inoculated with LP-BM5. We concluded that, based on histological examination and hepatic biochemical measurements, the retrovirus-infected animals were more resistant to APAP-induced liver injury. This could be due, in part, to alterations in the detoxification and activation metabolic pathways of APAP.

Acetaminophen↗
PubMed1996

Immunomodulation by pycnogenol in retrovirus-infected or ethanol-fed mice.

Pycnogenol is a commercial mixture of bioflavonoids that exhibits antioxidative activity. The effects of dietary pycnogenol on immune dysfunction in normal mice as well as those fed ethanol or infected with the LP-BM5 murine retrovirus were determined. The ethanol consumption and retrovirus infection caused abnormalities in the function and/or structure of a broad array of cells involved in humoral and cellular immunity. Pycnogenol enhanced in vitro IL-2 production by mitogen-stimulated splenocytes if its production was suppressed in ethanol-fed or retrovirus-infected mice. Mitogenesis of splenocytes did not show a significant change in mice treated with pycnogenol. It reduced the elevated levels of interleukin-6 produced in vitro by cells from retrovirus infected mice and IL-10 secreted by spleen cells from mice consuming ethanol. Natural killer cell cytotoxicity was increased with pycnogenol treatment.

Adjuvants, Immunologic↗
PubMed1996

Antioxidant activity of dioscorea and dehydroepiandrosterone (DHEA) in older humans.

Dioscorea is a yam steroid extract used in commercial steroid synthesis and consumed by people. DHEA is a steroid which declines with age, but without known activity. This study was designed to determine whether dioscorea supplementation could increase serum dehydroepiandrosterone sulfate (DHEAS) in humans and modulate lipid levels in older people. The subjects were selected volunteers aged 65-82 years. The serum DHEAS level, lipid peroxidation and lipid profile were assessed. Three weeks of dioscorea supplementation had no affect on serum DHEAS level. However DHEA intake of 85 mg/day increased serum DHEA levels 100.3%. DHEA and dioscorea significantly reduced serum lipid peroxidation, lowered serum triglycerides, phospholipid and increased HDL levels. Both DHEA and the steroid yam extract, dioscorea, have significant activities as antioxidant to modify serum lipid levels.

Aged↗
PubMed1996

Effect of ethanol and cocaine treatment of the immune system of v-Ha-ras-transgenic mice.

The objective was to investigate if the presence of the v-Ha-ras oncogene could induce immune changes different to the ones observed in normal mice. Therefore, we decided to use Oncomice, the transgenic mice with an activated v-Ha-ras oncogene under the control of the mouse mammary tumor virus-promoter, and their normal inbred counterparts, FVB mice. Both strains of mice were fed the Lieber-DeCarli liquid diet with ethanol or the isocaloric control diet and were injected daily with cocaine or saline. The percentage and absolute number of T and B lymphocytes in the spleen and thymus were determined. The in vitro production of TNF-alpha (tumor necrosis factor-alpha), IL-2 (interleukin-2) and IFN-gamma (interferon-gamma) by spleen cells, and the levels of serum sIL-2R (soluble IL-2 receptor) were also measured. Oncomice fed the Lieber-DeCarli ethanol diet or receiving either saline or cocaine injections presented a higher tumor incidence than Oncomice receiving the control diet. A reduced total number of thymocytes as well as absolute number of cells in all the subsets was found in Oncomice. Moreover, a decreased percentage of CD8+ cells was also observed in Oncomouse spleens. These features were even more marked in ethanol-treated Oncomice. Higher serum sIL-2R levels were observed in Oncomice, especially in mice treated with ethanol or cocaine. The results suggest that the oncogene product, P21ras, plays an important role in dysregulating the immune system and hence in favoring tumorigenesis.

Animals↗
PubMed1996

Vitamins and immunomodulation in AIDS.

Acquired immune deficiency syndrome (AIDS) is a clinical disorder caused by a retrovirus infection and represents the end point in a progressive sequence of immunosuppressive changes. Vitamins can enhance disease resistance in animals and humans. As such they are important co-factors in optimal functioning of the immune systems. In this article, the immunological and nutritional modifications caused by AIDS are summarized. The effects of murine and human retrovirus infection on vitamin status are analyzed as co-factors in the development of severe immune dysfunction, AIDS. The properties of immunoenhancing antioxidative vitamins, vitamin A, B6, B12, C, E, and beta-carotene, which are frequently low in AIDS patients, are evaluated relative to the development of immunodeficiency during retrovirus infection. Vitamin A, E, and B12 deficiency accelerated the development of AIDS with low T cells, whereas their normalization retarded the development of immune dysfunction. The interactions between these vitamins and the immune system in human AIDS patients and animal models of AIDS are reviewed. Our purpose is to provide data on how retrovirus infection can cause nutritional deficiencies that accentuate immune damage and to evaluate the potential therapeutic role of vitamins in the treatment of immune dysfunctions in AIDS patients.

Acquired Immunodeficiency Syndrome↗
PubMed1996

T-cell-receptor dose and the time of treatment during murine retrovirus infection for maintenance of immune function.

C57BL/6 mice were injected with different doses of human T-cell receptor (TCR) V beta 8.1 CDR1 peptide at different times after murine retrovirus (LP-BM5) infection. Injection with TCR V beta 8.1 CDR1 peptide largely prevented the retrovirus-induced reduction in B- and T-cell proliferation, and T-helper 1 (Th1) cytokines [interleukin-2 (IL-2) and interferon-gamma (IFN-gamma)] secretion. It also suppressed T-helper 2 (Th2) cytokines (IL-6 and IL-10) production, which was stimulated by retrovirus infection. These effects were accomplished using at least 100 micrograms of peptide per mouse and the most effective dose of peptide had to be given within 4 weeks after retrovirus infection. Immunization with doses above 100 micrograms/mouse as long as 4 weeks postinfection maintained natural killer (NK) cell activity during retrovirus infection. Reducing the dose of peptide or delaying it until the disease progressed towards early murine acquired immune deficiency syndrome (AIDS) allowed development of immune dysfunction. These studies provide data suggesting that immune dysfunction, induced by murine retrovirus infection, was largely prevented by TCR V beta CDR1 peptide injection.

Adjuvants, Immunologic↗
PubMed1996

Murine AIDS, a key to understanding retrovirus-induced immunodeficiency.

A murine AIDS model, induced by LP-BM5 murine leukemia virus (MuLV), has helped to investigate pathogenesis of acquired immunodeficiency syndrome (AIDS), cofactor involvement, and new treatment tests. LP-BM5 MuLV-infected mice characteristically develop hypergammaglobulinemia, splenomegaly, lymphadenopathy, T-cell functional deficiency, B-cell dysfunction, and, in the later stages, neurological signs including paralysis as well as susceptibility to opportunistic infections. The similarities between murine AIDS and human AIDS are striking, with similar changes in immune functions, T-cell differentiation, cytokine production, disease resistance, and oxidative stress. The well-characterized murine immunological system, availability of inbred strains, economy of using mice versus primate model, and similarities in immunodeficiency caused by human immunodeficiency virus (HIV) encouraged rapid development of the LP-BM5 murine AIDS model in the past decade.

Animals↗
PubMed1996

Vitamin E deficiency and immune dysfunction in retrovirus-infected C57BL/6 mice are prevented by T-cell receptor peptide treatment.

Female C57BL/6 mice were infected with LP-BM5 retrovirus, causing murine acquired immunodeficiency syndrome (AIDS), which is functionally similar to human AIDS. Retrovirus infection inhibited release of T-helper 1 cytokines, stimulated secretion of T-helper 2 cytokines and induced hepatic and cardiac vitamin E deficiency with increased lipid peroxides. We hypothesized that the immune dysfunction caused increased oxidation and loss of vitamin E. Because T-cell receptor (TCR) peptide treatment blocked the excessive stimulation of a T-cell subset by retroviral superantigens, we tested whether maintenance of normal immune function during infection prevented excessive oxidative damage. The TCR peptide treatments with doses > 100 microgram/mouse and administered 2-4 wk postinfection significantly inhibited the retrovirus-induced immune dysfunction, concomitantly reduced tissue oxidative damage and thereby largely maintained vitamin E concentration in the liver and heart. Reducing the dose of peptide or delaying administration until early murine AIDS had developed resulted in severe immune dysfunction that caused elevated tissue lipid peroxidation and loss of vitamin E. The TCR peptide treatment partially maintained production of interleukin-2 (IL-2) and prevented retrovirus-induced elevated production of IL-6 by splenocytes in vitro. In conclusion, TCR peptide treatment during murine retrovirus infection ameliorated immune dysfunction and thus prevented increases in tissue lipid peroxidation and vitamin E loss. T-cell immune dysfunction and its prevention by TCR peptide treatment is important in the therapy of vitamin E deficiency induced by retrovirus infection.

Adjuvants, Immunologic↗
PubMed1996

Dehydroepiandrosterone and diseases of aging.

Dehydroepiandrosterone (DHEA; prasterone) is a major adrenal hormone with no well accepted function. In both animals and humans, low DHEA levels occur with the development of a number of the problems of aging: immunosenesence, increased mortality, increased incidence of several cancers, loss of sleep, decreased feelings of well-being, osteoporosis and atherosclerosis. DHEA replacement in aged mice significantly normalised immunosenescence, suggesting that this hormone plays a key role in aging and immune regulation in mice. Similarly, osteoclasts and lymphoid cells were stimulated by DHEA replacement, an effect that may delay osteoporosis. Recent studies do not support the original suggestion that low serum DHEA levels are associated with Alzheimer's disease and other forms of cognitive dysfunction in the elderly. As DHEA modulates energy metabolism, low levels should affect lipogenesis and gluconeogenesis, increasing the risk of diabetes mellitus and heart disease. Most of the effects of DHEA replacement have been extrapolated from epidemiological or animal model studies, and need to be tested in human trials. Studies that have been conducted in humans show essentially no toxicity of DHEA treatment at dosages that restore serum levels, with evidence of normalisation in some aging physiological systems. Thus, DHEA deficiency may expedite the development of some diseases that are common in the elderly.

Aged↗
PubMed1995

T cell receptor V beta complementarity-determining region 1 peptide administration moderates immune dysfunction and cytokine dysregulation induced by murine retrovirus infection.

Murine AIDS, induced by LP-BM5 murine leukemia retrovirus infection, causes a progressive and profound immunodeficiency in female C57B1/6 mice. Previously, we reported that autoantibodies were elevated during the initiation phases of this murine retrovirus infection and bound peptide determinants corresponding to CDR1 of several TCR V beta-chains. Therefore, we designed studies to determine whether administration of a major autoimmunogenic TCR V beta CDR1 peptide before or after infection with LP-BM5 retrovirus would modulate retrovirus-induced dysregulation of T cell function. Administration of the TCR V beta CDR1 peptide before murine retrovirus infection significantly prevented its suppression of splenic NK cell activity, T and B cell proliferation, and monokine (IL-6 and TNF-alpha) and Th1 cytokine (IL-2 and IFN-gamma) release by splenocytes, and inhibited retrovirus-induced elevation of Th2 cytokine (IL-5 and IL-10). Similar data were obtained with peptide immunization 2 wk after murine retrovirus infection at 6 and 16 wk postinfection. However, delaying peptide immunization until severe suppression of T and B cell mitogenesis had occurred did not restore their functions. Immunization with TCR V beta peptide prevents development of retrovirus-induced immune dysfunction, which suggests a possible pathogenic role of autoreactive T cells as regulatory elements.

Amino Acid Sequence↗
PubMed1995

Vitamin E supplementation with interferon-gamma administration retards immune dysfunction during murine retrovirus infection.

Murine retrovirus infection induces loss of vitamin E and immune dysfunction with loss of cytokine production by T-helper cells. Therefore interferon-gamma (IFN-gamma) was given during dietary vitamin E supplementation to effectively prevent murine retrovirus-induced immunosuppression, cytokine dysregulation, and development of murine AIDS. Administration of IFN-gamma during vitamin E supplementation significantly prevented development of retrovirus-induced suppression of splenic natural killer cell activity and T cell proliferation. It also significantly slowed retrovirus-induced elevation of T helper (Th) 2 cytokine [interleukin (IL)-4, IL-5, and IL-10] production and monokine (IL-6 and tumor necrosis factor-alpha) secretion by splenocytes. The treatment also prevented loss of Th1 cytokine (IL-2 and IFN-gamma) secretion by splenocytes from retrovirus-infected mice alleviating splenomegaly and hypergammaglobulinemia. The combined therapy had an additive therapeutic impact. It was more effective than IFN-gamma treatment or vitamin E supplementation alone in delaying the development of retrovirus-induced immunosuppression with its cytokine dysregulation.

Animals↗
PubMed1995

Autoantibodies against peptide-defined epitopes of T-cell receptors in retrovirally infected humans and mice.

Autoantibodies directed against peptide-defined epitopes of T-cell receptors occur in the serum of healthy humans with the levels and isotypic expression dependent upon physiological changes (aging, pregnancy) or upon the development of autoimmune disease. We carried out investigations of autoantibodies against Tcr peptide-defined epitopes in retroviral infections of humans (HIV-1) and mice (LP-BM5 strain of murine leukemia virus) to determine whether infection with these agents disrupted the regulation of the production of these antibodies. Retroviral infection in humans resulted in increased levels of autoantibody production against putative immunoregulatory regions of the Tcr beta chain (V beta CDR1 and Fr3), a result reflecting a disruption of regulation. In addition, antigenic mimicry was observed with a cross-reaction shared between the common portion of the V3 neutralizing loop of the HIV-1 gp120 molecule and the joining segment of T-cell receptors (J beta). Infection of mice with the defective retrovirus resulted in the induction of antibodies directed particularly against V beta CDR1 peptide-defined determinants. Analysis of the virally induced response to a set of 8 CDR1 peptide epitopes indicated a selectivity to the process. It was possible to partially reverse aberrant cytokine changes correlated with the onset of murine MAIDS by administration of T-cell receptor peptides in saline. These results show that retroviral infection in humans and mice has a profound dysfunctional effect on the regulation of autoantibodies to T-cell receptors. The function of these autoantibodies in the immunopathogenesis of acquired immunodeficiency remains to be determined.

Acquired Immunodeficiency Syndrome↗
PubMed1995

Modulation of immune function and cytokine production by various levels of vitamin E supplementation during murine AIDS.

Female C57BL/6 mice were infected with LP-BM5 retrovirus, causing murine AIDS which is functionally similar to human AIDS. Dietary supplementation, with a 15-, 150- and 450-fold increase of vitamin E in a liquid diet, significantly restored levels of interleukin-2 (IL) and interferon-gamma produced by splenocytes, which were suppressed by retrovirus infection. Retrovirus infection elevated levels of IL-6 and IL-10 produced by splenocytes, which were significantly normalized by all levels of vitamin E supplementation, respectively. Increased levels of IL-6 and tumor necrosis factor-alpha, produced by splenocytes during progression to murine AIDS, were also significantly normalized by all levels of vitamin E supplementation. Vitamin E supplementation restored retrovirus-suppressed splenocyte proliferation and natural killer cell cytotoxicity. Vitamin E supplementation also alleviated the AIDS symptoms: splenomegaly and hypergammaglobulinemia. These data indicate that dietary vitamin E supplementation at extremely high levels was not immunotoxic, and can modulate cytokine release and normalize immune dysfunctions during progression to murine AIDS. It should favorably affect host resistance and thereby retard the development of AIDS.

Animals↗
PubMed1995

Kinetics of cytokine production by thymocytes during murine AIDS caused by LP-BM5 retrovirus infection.

C57BL 6 mice inoculated with the murine leukemia retrovirus mixture, LP-BM5, rapidly produce murine AIDS with many functional similarities to human AIDS. Human HIV infection has recently been shown to inhibit thymocyte maturation. Therefore, the kinetics of the proliferation of thymocytes induced by Con-canavalin A (ConA) and levels of cytokines produced by in vitro ConA-stimulated thymocytes were examined during the progression of murine AIDS. The proliferation of thymocytes induced by ConA was significantly enhanced by retrovirus infection at 4 weeks post-infection compared to control, but significantly inhibited during 8-12 weeks post-infection. Release of IL-2 by ConA-stimulated thymocytes was significantly increased by retrovirus infection during 2-5 weeks post-infection and 11-18 weeks post-infection compared to control, but significantly decreased during 7-9 weeks post-infection. Secretion of IL-4 by ConA-stimulated thymocytes was significantly enhanced by retrovirus infection from 5 to 18 weeks post-infection compared to control. The level of IL-6 produced by ConA-stimulated thymocytes was significantly inhibited by retrovirus infection at the beginning of retrovirus infection (2-9 weeks), but significantly elevated after 11 weeks post-infection compared to control. Release of IFNgamma by ConA-stimulated thymocytes, however, was significantly enhanced during the whole period of retrovirus infection compared to control, while it surged at 13 weeks post-infection. We conclude that retrovirus infection affects the thymus, producing altered T-cell differentiation via the dysregulation of thymocyte cytokine secretion.

Animals↗
PubMed1995

Production of IgG autoantibodies to TCRs in mice infected with the retrovirus LP-BM5.

Autoantibodies (AAbs) directed against particular segments of the variable region of TCR beta chains occur in normal humans and in certain autoimmune diseases, but the factors regulating the appearance of such antibodies are unknown. We report that AAbs binding a peptide determinant corresponding to the CDR1 of the V beta domain are elevated in C57BL/6 mice following infection with the LP-BM5 murine leukemia retrovirus mixture, a treatment used to induce murine AIDS. The elevation of the level of these AAbs is an early event following retroviral infection which corresponds in part to the general polyclonal activation of the B cells, but a selectivity for particular V beta sequences is apparent later. This suggests that the appearance of these antibodies may play a part in the subsequent development of immunodeficiency. Since the antibodies studied are of the IgG isotype, both T cells and B cells are involved in their elaboration.

Amino Acid Sequence↗
PubMed1994

Long-term dietary vitamin E retards development of retrovirus-induced disregulation in cytokine production.

A 15-fold increase in dietary vitamin E (160 IU/liter) normalized hepatic and serum levels of vitamin E normally reduced by retrovirus infection. It also significantly retarded development of splenomegaly and hypergammaglobulinemia induced by retrovirus infection, while significantly restoring release of interleukin-2 (IL) and interferon-gamma by splenocytes which are suppressed by retrovirus infection. Retrovirus infection elevated production of IL-4 and IL-6 by splenocytes, but this elevation was inhibited by vitamin E. Increased levels of IL-6 and tumor necrosis factor-alpha produced by splenocytes during progression to murine AIDS were also inhibited by vitamin E. Vitamin E supplementation also helped restore retrovirus-suppressed splenocyte proliferation. These data indicate that vitamin E supplementation can help overcome retrovirus-induced reduction in tissue vitamin E, modulate cytokine release, and normalize immune dysfunctions during progression to murine AIDS.

Animals↗