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Query: UMLS:C0019693 (HIV)
 170,526 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Tumor necrosis factor is a cytokine that participates in the mediation of numerous diseases associated with inflammation, cachexia, shock, and tissue injury. Early studies of the biology of TNF delineated its hormonal actions as well as its systemic toxicity. More recent investigations have drawn attention to its paracrine actions that predominate when it is produced locally in the brain or vital organs. For instance, when compartmentalized production of TNF occurs in the central nervous system it directly mediates fever, anorexia, and altered whole-body metabolism. Since these changes are mediated within the neural network they occur independently of simultaneously sampled serum TNF levels. These paracrine actions of TNF have implications for diseases associated with production of TNF in tissues (e.g. HIV cerebritis, multiple sclerosis, cerebral malaria and cancer), because they may differ markedly from the hormone like-actions associated with systemic release. Since TNF may be beneficial in some diseases yet injurious in others, both the hormonal and paracrine actions must be precisely defined in order to formulate novel treatment strategies based on either enhancing its useful effects, or suppressing toxicity.
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PMID:Tumor necrosis factor in metabolism of disease: hormonal actions versus local tissue effects. 134 May 27

A clinical AIDS case definition is needed for surveillance in countries where the CDC case definition is not practical. To derive such a definition, we compared 110 HIV-seropositive and 135 randomly selected HIV-seronegative adult medical-ward inpatients in Brazil. Multivariate analysis of clinical signs and symptoms and simple diagnoses resulted in a discriminant function with sensitivity of 89% and specificity of 96% in predicting for AIDS. These data were the empirical basis for a clinical definition of AIDS in adults drafted in a Caracas, Venezuela, workshop sponsored by the Pan American Health Organization. The revised "Caracas" definition presented here requires a positive HIV serology, the absence of cancer or other cause of immunosuppression, plus > or = 10 cumulative points, as follows: Kaposi's sarcoma (10 points); extrapulmonary/noncavitary pulmonary tuberculosis (10); oral candidiasis or hairy leukoplakia (5); cavitary pulmonary/unspecified tuberculosis (5); herpes zoster < 60 years of age (5); CNS dysfunction (5); diarrhea > or = 1 month (2); fever > or = 1 month (2); cachexia or > 10% weight loss (2); asthenia > or = 1 month (2); persistent dermatitis (2); anemia, lymphopenia, or thrombocytopenia (2); persistent cough or any pneumonia except TB (2); and lymphadenopathy > or = 1 cm at > or = 2 noninguinal sites for > or = 1 month (2). This definition has a sensitivity of 95% and a specificity of 100% (91% without HIV serology) when applied to the Brazilian patients in this study. The Caracas definition has been adopted by Brazil, Honduras, and Surinam, and is in validation elsewhere. The use of a reasonably sensitive and specific case definition commensurate with available diagnostic resources should facilitate AIDS surveillance in developing countries.
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PMID:A simplified surveillance case definition of AIDS derived from empirical clinical data. The Clinical AIDS Study Group, and the Working Group on AIDS case definition. 145 32

High levels of an unusual acid-labile interferon (IFN) alpha in sera of patients with human immunodeficiency virus (HIV) infection are associated with disease progression to acquired immunodeficiency syndrome (AIDS). Since IFNs have been shown to enhance the cytotoxic actions of tumor necrosis factor (TNF), a potent mediator of inflammation and cachexia, a study was undertaken to investigate whether the acid-labile IFN alpha produced in AIDS can regulate TNF receptor expression. The expression of TNF receptors was determined by studying the interaction of [125I]TNF with cellular receptors. The results show the acid-labile IFN alpha present in AIDS sera is capable of inducing the expression of cellular receptors for TNF. The extent of induction of TNF receptors depends on the concentration of the acid-labile IFN alpha in the AIDS sera. There is no significant induction of TNF receptors when the AIDS sera are preneutralized with polyclonal anti-IFN alpha antibodies. It is also shown that the synthesis of TNF by peripheral blood monocytes (PBM) from patients with HIV infection is enhanced during the progression of HIV infection in vivo. Thus, the TNF system is activated in patients with HIV infection. This activation may be a contributing factor to some of the physiological disturbances including the wasting syndrome observed in AIDS.
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PMID:Regulation of tumor necrosis factor receptor expression by acid-labile interferon-alpha from AIDS sera. 165 73

We measured the serum concentrations of tumor necrosis factor (TNF-alpha), interleukin 1-beta (IL-1-beta), p24 antigen, CD4+/CD8+ cells and immunoglobulins in 35 children at various stages of human immunodeficiency virus infection. Serum TNF-alpha concentrations were significantly higher in children with lymphocytic interstitial pneumonitis and in children with mildly symptomatic illness than in asymptomatic children or children with acquired immunodeficiency syndrome. In addition serum IL-1 concentrations were significantly higher in patients with lymphocytic interstitial pneumonitis than in asymptomatic, mildly symptomatic, or acquired immunodeficiency syndrome patients. Children with lymphocytic interstitial pneumonitis had the highest serum TNF-alpha and IL-1 concentrations. Among symptomatic children serum TNF-alpha concentrations correlated positively with those of IL-1, and both were inversely related to the amount of p24 antigen. TNF-alpha values in excess of 50 pg/ml were observed more frequently among patients with CD4+ cell count greater than 400/mm3 than in those with CD4+ cell count less than 400/mm3. We did not find any association between elevated TNF-alpha concentrations and cachexia, opportunistic infections or progressive encephalopathy.
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PMID:Serum tumor necrosis factor alpha, interleukin 1-beta, p24 antigen concentrations and CD4+ cells at various stages of human immunodeficiency virus 1 infection in children. 167 77

Pentoxifylline (Trental), used routinely for the treatment of intermittent claudication, has been shown previously to decrease the levels of tumor necrosis factors-alpha (TNF-alpha) RNA in cancer patients and to lead to a general improvement of well being. Increased TNF-alpha levels have been observed not only in cancer patients but also in cachectic patients with the acquired immunodeficiency syndrome (AIDS), and TNF-alpha is known to increase the expression of the human immunodeficiency virus type 1 (HIV-1) via activating its long terminal repeat (LTR). Moreover, TNF-alpha decreases the therapeutic efficacy of zidovudine (AZT). Here we show a significant decrease in HIV-1 replication by pentoxifylline in infected human peripheral blood mononuclear cells. The reduction was proportional to the downregulation of expression of a reporter gene, the bacterial gene for chloramphenicol acetyl transferase, linked to the HIV-1 LTR in human monocytoid cells. We conclude that patients with AIDS may benefit from pentoxifylline treatment because of its blockage of TNF-alpha-mediated HIV-1 upregulation, from increased efficacy of AZT, and also from improvement in TNF-alpha-induced cachexia.
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PMID:Pentoxifylline (Trental) decreases the replication of the human immunodeficiency virus type 1 in human peripheral blood mononuclear cells and in cultured T cells. 130 72

Tryptophan (Trp) is an indispensable amino acid required for biosynthesis of proteins, serotonin and niacin. Indoleamine 2,3-dioxygenase (IDO) is induced by infections, viruses, lipopolysaccharides, or interferons (IFNs) and this results in significant catabolism of Trp along the kynurenine (Kyn) pathway. Intracellular growth of Toxoplasma gondii and Chlamydia psittaci in human fibroblasts in vitro is inhibited by IFN-gamma and this inhibition is negated by extra Trp in the medium. Similarly, growth of a number of human cell lines in vitro is inhibited by IFN-gamma and addition of extra Trp restores growth. Thus, in some in vitro systems, antiproliferative effects of IFN-gamma are mediated by induced depletion of Trp. We find that cancer patients given Type I or Type II IFNs can induce IDO which results in decreased serum Trp levels (20-50% of pretreatment) and increased urinary metabolites of the Kyn pathway (5 to 500 fold of pretreatment). We speculate that in vivo antineoplastic effects of IFNs and clinical side effects are mediated, at least in part, by a general or localized depletion of Trp. In view of reported increases of IFNs in autoimmune diseases and our earlier findings of elevated urinary Trp metabolites in autoimmune diseases, it seems likely that systemic or local depletion of Trp occurs in autoimmune diseases and may relate to degeneration, wasting and other symptoms in such diseases. We find high levels of IDO in cells isolated from synovia of arthritic joints. IFNs are also elevated in human immunodeficiency virus (HIV) patients and increasing IFN levels are associated with a worsening prognosis. We propose that IDO is induced chronically by HIV infection, is further increased by opportunistic infections, and that this chronic loss of Trp initiates mechanisms responsible for the cachexia, dementia, diarrhea and possibly immunosuppression of AIDS patients. In these symptoms, AIDS resembles classical pellagra due to dietary deficiency of Trp and niacin. In preliminary studies, others report low levels of Trp and serotonin, and elevated levels of Kyn and quinolinic acid in AIDS patients. The implications of these data in cancer, autoimmune diseases and AIDS are discussed.
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PMID:Implications of interferon-induced tryptophan catabolism in cancer, auto-immune diseases and AIDS. 172 46

Growth hormone (somatotropin) is a potent anabolic protein currently being evaluated clinically in cachexia associated with malignancy and human immunodeficiency virus (HIV) disease. Growth hormone can also lead to enhancement of lectin-mediated cellular proliferation, macrophage activation, and cytokine induction, events linked to induction of latent HIV in vitro. We thus explored the ability of recombinant human growth hormone (rhGH) to affect viral replication in acute and chronic HIV infection, and to alter transcription at the HIV-1 long terminal repeat (LTR). A clone of promonocytic cells, chronically infected with HIV-1 and susceptible to viral induction by a variety of cytokines and protein kinase C activators, was unperturbed by rhGH used over broad concentrations (10 to 500 ng/mL) and time intervals. This unresponsiveness paralleled the lack of effect of rhGH on HIV-associated trans-activation in both monocytic and CD4+ T-cell lines. In contrast, rhGH enhanced viral replication in acutely infected peripheral blood mononuclear cells (PBMC) by twofold to 20-fold, albeit having no adverse effect on the antiviral efficacy of zidovudine (AZT). Augmentation of HIV growth correlated with stimulation of cellular DNA synthetic responses and an increase in tumor necrosis factor-alpha (TNF-alpha) secretion. These data are discussed in the context of ongoing clinical trials of rhGH in HIV-seropositive individuals with wasting syndromes.
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PMID:Effect of recombinant human growth hormone on acute and chronic human immunodeficiency virus infection in vitro. 173 91

We have observed typical cytomegalovirus cytopathology associated with multifocal inflammatory and necrotic lesions of peripheral nerve in biopsy specimens from 4 patients who developed a rapidly progressive, multifocal neuropathy late in the course of human immunodeficiency virus infection. The inflammatory infiltrates, which contained numerous polymorphonuclear cells, were associated with mixed, axonal, and demyelinative lesions of nerve fibers. One of these patients improved on treatment with DHPG (9-[2-hydroxy-l(hydroxymethyl) ethoxymethyl] guanine) and remains stable after 18 months. The other 3 died soon after the onset of the neuropathy. In another patient with acquired immunodeficiency syndrome, who developed a severe, predominantly motor neuropathy of the lower limbs, the nerve biopsy did not reveal cytomegalovirus inclusions, but the neurological deficit improved on treatment with DHPG. The patient died from cachexia 2 months later; numerous cytomegalovirus lesions were found in the spinal cord at the time of postmortem examination. The multifocal necrotic endoneurial nerve lesions with polymorphonuclear cell infiltration we describe may help identify cytomegalovirus neuropathy when characteristic inclusions are not present in the biopsy specimen.
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PMID:Cytomegalovirus neuropathy in acquired immunodeficiency syndrome: a clinical and pathological study. 184 86

Endocrine function was prospectively evaluated in 98 patients (73 men and 25 women) infected by HIV in various stages of illness: Centers for Disease Control groups II (19), III (20), IVA and IVC2 (27), IVC1 and IVD (32). Testing included baseline and post-stimulation evaluation of gonadal, thyroidal, and adrenal axes. Although adrenal function was within normal values in most cases, with no differences between patient groups, nine out of 98 patients had either a low baseline or post-stimulation serum cortisol, cytomegalovirus adrenalitis being suspected in two cases. Mineralocorticoid response was normal in all individuals. The main abnormalities were sick euthyroid syndrome with low tri-idothyronine and/or thyroxine in 16% of patients and hypotestosteronemia in 29% of men with AIDS. These abnormalities, related to a functional deficiency of the hypothalamic-pituitary axis, were highly correlated with the degree of illness, i.e. weight loss and low CD4+ cell count. It was concluded that endocrine dysfunction in HIV-infected patients is rarely of clinical significance, that it is related more to cachexia and advanced disease than to HIV or opportunistic infections, and that it could serve as a prognostic marker.
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PMID:Endocrine function in 98 HIV-infected patients: a prospective study. 188 45

In addition to the induction of tumor regression, tumor necrosis factor (TNF) has been implicated as the causative agent in a number of pathologies, including cachexia, septic shock, rheumatoid arthritis, autoimmunity, and induction of HIV expression. We propose that this complex physiology might be manifest by different forms of TNF: the 17 kd secretory component, the 26 kd transmembrane form, or both. To determine whether the 26 kd form of TNF was biologically active and whether its biology differed from that of the secretory component, we generated uncleavable and solely secretable mutants of TNF and studied their biological activities. We found that an uncleavable mutant of the 26 kd cell surface transmembrane form of TNF kills tumor cells and virus-infected cells by cell-to-cell contact, and that TNF need not be internalized by its target to kill. Thus, the 26 kd integral transmembrane form of TNF may function in vivo to kill tumor cells and other targets locally in contrast to the systemic bioactivity of the secretory component.
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PMID:A nonsecretable cell surface mutant of tumor necrosis factor (TNF) kills by cell-to-cell contact. 220 85


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