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

Freedom from infection is the result of many tiers of immune defenses that harmoniously interact to rid the body of microorganisms and their products, which are perceived as foreign. The ability to distinguish self from nonself is embodied in lymphocytes, which serve both effector and regulatory functions. Through the elaboration of cytokines and immunoglobulins, lymphocytes recruit nonspecific immune effectors, focus their activity, and modulate the intensity of the immune response. The phylogenetically more primitive complement system serves a similar function. Although congenital defects in immune function occur, by far the most common causes of immunodeficiency are acquired and occur in patients treated for cancer with myelosuppressive, cytolytic drugs and in transplant recipients treated with immunosuppressants. HIV infection and malnutrition are responsible for even larger numbers of immunocompromised patients worldwide. The nature and severity of infections that occur as a result of immunodeficiency vary as a function of the immune effector targeted and the degree to which it is dysfunctional. Granulocytopenia is well tolerated unless the absolute number of circulating cells falls below 500/mm3. Profound granulocytopenia and deficits of neutrophil function are often manifest as bacterial or fungal infections. Complement deficiency predisposes to infection with encapsulated bacteria such as pneumococci, meningococci, and Haemophilus influenzae. T cells play such a central role in the immune response that their derangement is associated with susceptibility to almost any potential pathogen. These patients often succumb to mortal opportunistic infections. Recent advances in hybridoma and recombinant DNA technology have provided us with immunologic reagents that enable us to manipulate the immune response. Anti-CD3 monoclonal antibody has permitted salvage of solid organ transplants in well-defined clinical settings. Monoclonal antibodies against TNF-alpha and lipopolysaccharide may alter the consequences of gram-negative sepsis. Alternatively, recombinant cytokines have been associated with clinically significant tumor regression in selected patients, presumably by enhancing the nascent antitumor immune response. The development of immunologic reagents such as these in concert with our growing understanding of the immune system may translate to improved care for immunocompromised patients.
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PMID:Immune function and dysfunction. A primer for the radiologist. 157 Mar 93

The design, synthesis, and biological evaluation of several unsaturated acyclonucleosides related to augustmycin A are described. The (propargyloxy)methyl acyclonucleoside analogues of 6-chloropurine, adenine, 6-methoxypurine, hypoxanthine, 6-mercaptopurine, and azathioprine have been prepared. The 9-[(propargyloxy)methyl]adenine (5) and 9-[(propargyloxy)methyl]hypoxanthine (12) analogues were converted to the corresponding 5'-tributylstannyl intermediates (9 and 13), respectively, which gave 9-[[[(Z)-5-iodo-5-propenyl]oxy]methyl]adenine (10) and 9-[[[(Z)-5-iodo-5-propenyl]oxy]methyl]hypoxanthine (14), respectively, after iododestannylation. The [125I]-radiolabeled congeners of 10 and 14 were prepared as potential metabolic markers. Among the unsaturated acyclonucleosides tested, 9-[(propargyloxy)methyl]-6-chloropurine (3), 9-[(propargyloxy)methyl]-6-mercaptopurine (15), 9-[(propargyloxy)methyl]azathioprine (17), and angustmycin A analogue 10 showed inhibition of cancer cell growth, but only at a minimal level, and 17 also showed 14% cancer cell death in vitro. Compound 10 provided approximately 50% protection against HIV at 10(-4) M concentrations. Biodistribution results of [125I]-10 in mice indicate that compound 10 is readily metabolized via deiodination in vivo, possibly by serving as a substrate for the enzyme S-adenosyl-L-homocysteine hydrolase.
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PMID:Synthesis and biological studies of unsaturated acyclonucleoside analogues of S-adenosyl-L-homocysteine hydrolase inhibitors. 157 37

The Acquired Immunodeficiency Syndrome (AIDS) has involved the pediatric age group and is especially prevalent in babies born of mothers who are intravenous drug abusers or prostitutes. Approximately 30% of children born to mothers who are seropositive for the human immunodeficiency virus (HIV) will develop HIV infection. There are several important differences in children and adults with AIDS. The incubation period of the disease is shorter, and initial clinical manifestations occur earlier in children. In addition, certain infections are more common in children, and the different types of malignancy, especially Kaposi's sarcoma, are unusual in the pediatric age group. The altered immune system involves both T cells and humoral immunity and increases susceptibility to a variety of infections, particularly opportunistic organisms. In this publication the complications of pediatric AIDS involving the lungs, cardiovascular system, gastrointestinal tract, genitourinary system, and neurological system are described. The most common pulmonary complications in our experience are Pneumocystis carinii pneumonia and pulmonary lymphoid hyperplasia. The spectrum of cardiovascular involvement in pediatric AIDS includes myocarditis, pericarditis, and infectious endocarditis. Gastrointestinal tract involvement is usually due to opportunistic organisms that produce esophagitis, gastritis, and colitis. Abdominal lymphadenopathy is a common finding either due to disseminating Mycobacterium avium-intracellulare infection or nonspecific lymphadenopathy. Although cholangitis is more commonly seen in adults, it may occur in children with AIDS and, in most cases, is due to related opportunistic infections. Genitourinary infections may be the first evidence of HIV disease. Cystitis, pyelonephritis, renal abscesses, and nephropathy with renal insufficiency are complications of pediatric AIDS. A variety of neurological abnormalities may occur in pediatric AIDS. The most common cause of neurological dysfunction in children with AIDS is HIV neuropathy. We present the many complications of AIDS in children demonstrated by a variety of imaging modalities, emphasizing the importance of diagnostic imaging in children with this disease.
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PMID:Radiology of AIDS in the pediatric patient. 157 31

Infection with the human immunodeficiency virus type 1 (HIV-1) results in a variety of pathological changes culminating in the acquired immune deficiency syndrome (AIDS). While most of these changes can readily be accounted for either by direct effects of HIV-1 on the immune system or by indirect effects of secondary infectious agents as a result of faulty immune surveillance, the direct cause for a number of disease states, including some neuropathies, myopathies, nephropathy, thrombocytopenia, wasting syndromes and increased incidence of cancers (primarily lymphoma) has remained an enigma. We have recently shown that the HIV-1 protease, a viral encoded enzyme necessary for virus maturation and infectivity, can cleave a variety of host cell cytoskeletal proteins in vitro. Potential substrates for the HIV-1 protease are found in all of the cell types affected in these unexplained diseases. Recent proposals suggest that elements of the cytoskeleton may play an important role in the regulation of large scale genetic regulation. We propose that some of the degenerative changes associated with infection by HIV-1 are a direct consequence of cleavage of host cell cytoskeletal proteins, which in turn may be responsible for the increased incidence of cancer in HIV-1 infected individuals as a result of the perturbation of the regulation of gene expression by cytoskeletal components.
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PMID:Potential role of the viral protease in human immunodeficiency virus type 1 associated pathogenesis. 158 3

Recombinant human colony-stimulating factors (CSFs) have potential for wide use in the areas of oncology and infectious disease. Granulocyte CSF and granulocyte-macrophage CSF currently are approved for use in the treatment of neutropenia associated with standard-dose cancer chemotherapy and bone marrow transplantation, respectively. Other settings in which these agents have shown promise are dose-intensive chemotherapy, enhancement of progenitor cell support, primary and acquired neutropenias, myelodysplasia, aplastic anemia, and cytopenias associated with human immunodeficiency virus infection or myelosuppressive therapies for such infection or related conditions. Clinical findings in these areas are encouraging, and potential exists for additional applications of the CSFs.
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PMID:Colony-stimulating factors: clinical applications. 159 11

Chronically immunosuppressed individuals are susceptible to lymphoreticular tumors. Up to 15% of patients with congenital deficiencies such as ataxia=telangiectasia may develop malignancies, mainly high-grade B cell non=Hodgkin's lymphomas (NHLs). AIDS lymphomas are comprised of NHLs including Burkitt's lymphoma (BL) and primary cerebral lymphomas (PCLs). Almost 3% of all AIDS patients (2824 of 97,258 cases) developed NHL. Epstein-Barr virus (EBV) as a co-factor in AIDS lymphomagenesis has been studied: in 12 cases of 24 AIDS lymphomas EBV by DNA in situ hybridization was found. In an analysis of 6 primary cerebral lymphomas, .5 were positive for EBV DNA by Southern blotting. In Burkitt's lymphoma the characteristic genetic alteration affects the c-myc oncogene. In 1/3 of BL p53 mutations were found but none in the 43 NHLs suggesting that p53 mutations and c-myc activation act synergistically in the pathogenesis of these tumors. Cytotoxic agents dideoxyinosine, dideoxycytosine, and zidovudine may cause secondary neoplasia. 8 of 55 AIDS patients under zidovudine treatment developed high-grade lymphoma 23.8 months subsequently; recently doses were reduced. PCL was found in 21 of 90 patients. A 5.2 months survival was associated with combined treatment with cyclophosphamide, Oncovin (vincristine), methotrexate, etoposide, and cytosine arabinoside compared with 11.3 months with chemotherapy. Colony-stimulating factors (CSFs) alleviate drug-induced myelotoxicity and zidovudine-induced neutropenia, however, l8 of 11 patients receiving granulocyte-macrophage CSF developed hematological toxicity. Interleukine-2 produced by T-helper cells enhancing tumor cells cytotoxicity has been used in AIDS-associated cryptosporidial diarrhea and in 4 patients with AIDS lymphoma with modest response, but its stimulation of the HIV-infected substrate may increase viral proliferation.
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PMID:AIDS lymphomas. 161 63

The human immunodeficiency virus type I (HIV-1) regulatory gene, tat III, is a powerful trans-activator of gene expression from the viral long terminal repeat and is essential for HIV replication. In addition, tat III protein has been shown to be immunosuppressive as indicated by the inhibition of antigen mediated T-cell proliferation. To further test whether tat III might play a direct role in the immunosuppressive effects of HIV-1 in addition to its role in virus replication, we examined the regulation of interleukin 4 (IL-4) receptors on a human B-lymphoblastoid cell line (Raji) transfected with HIV-1 tat gene (Raji-tat III). We used radioligand receptor binding analysis for cell surface expression and Northern blot analysis for the expression of human IL-4 receptor gene in Raji-tat III cells. Control Raji cells expressed 1383 +/- 361 (SE; n = 3) IL-4 binding sites/cell with a dissociation constant (Kd) of 144 +/- 27 pM (n = 3). However, Raji-tat III cells expressed about three times higher IL-4 receptors (4000 +/- 633 IL-4 binding sites/cell; P less than 0.03 compared to Raji cells) with a similar Kd of 273 +/- 90 pM (n = 3; P greater than 0.05 compared to Raji cells). Whereas both Raji and Raji-tat III cells exhibited a single mRNA species (approximately 4 kilobases) of IL-4 receptors by Northern blot analysis, the mRNA level was about 3-fold higher in Raji-tat III cells compared to Raji cells. Cycloheximide inhibited the expression of IL-4 receptors by 50% in about 2 h in both cell types indicating both the half-life of IL-4 receptors and the requirement for protein synthesis for the tat III up-regulation of IL-4 receptors. Since IL-4 under certain circumstances has been shown to be immunosuppressant, our observation that the HIV-1 tat gene up-regulates IL-4 receptors suggests the possibility that the immunosuppressive effects of HIV-1 are mediated at least in part through IL-4 receptors.
Cancer Res 1992 Jul 01
PMID:Human immunodeficiency virus type 1 tat gene up-regulates interleukin 4 receptors on a human B-lymphoblastoid cell line. 161 47

The lectin-like protein analogous to bovine conglutinin was purified from human serum. The carbohydrate-binding ability of conglutinin-like protein was inhibited by D-mannose, N-acetylglucosamine and L-fucose as well as by mannan-containing oligosaccharides. By applying a lectin-based ELISA system it was demonstrated that conglutinin-like protein binds to human immunodeficiency virus-1 (HIV-1) glycoprotein 120 (gp120) via its carbohydrate binding site. In vitro experiments with T-lymphoblastoid CEM cells revealed that conglutinin-like protein abolishes infection by HIV-1; a 50% cytoprotective concentration of 23.9 micrograms/ml was measured. These findings demonstrate that human conglutinin-like protein binds to HIV-gp120 and inhibits, under the described in vitro conditions, CEM cell infection.
Jpn J Cancer Res 1992 May
PMID:Inhibition of human immunodeficiency virus-1 infection by human conglutinin-like protein: in vitro studies. 161 96

Serological markers of hepatitis A, B, and Delta and human immunodeficiency viruses were studied in 25 children receiving cancer chemotherapy. Eighty-eight percent had pre-existing HAV immunity which was unaltered by chemotherapy. HDV infection was observed in 8% while HIV was conspicuous by its absence. Active HBV infection, observed in 76% of the children, was asymptomatic in the majority and was accompanied by a high incidence of HBe antigenaemia (57.9%) and its persistence. Pre-existing anti-HBs failed to prevent HBV infection recurrence, which was, however, transient and self-limiting. Multiple blood transfusions and repeated parenteral exposures appeared to be the possible sources of HBV acquisition. Transmission to close contacts was also observed. The study suggests that although HBV vaccine might not be protective against HBV infection in patients receiving cancer chemotherapy, it may prevent its persistence and thereby help in reducing chronic liver disease-related morbidity and a highly infectious reservoir. Strict HBV screening of blood donors, exclusive use of disposable equipment, and vaccination of close contacts of cancer patients is recommended, particularly in HBV endemic third-world countries.
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PMID:Infection with hepatitis A, B, delta, and human immunodeficiency viruses in children receiving cycled cancer chemotherapy. 162 14

This review describes the potential role of oxidative stress as a cofactor of disease progression from asymptomatic human immunodeficiency virus (HIV) infection to the acquired immunodeficiency syndrome (AIDS). Oxidative stress is a known activator of HIV replication in vitro through the activation of a factor that binds to a DNA-binding protein, NF-kappa B, which in turn stimulates HIV gene expression by acting on the promoter region of the viral long terminal repeat. Tumor necrosis factor alpha (TNF-alpha), an essential cytokine produced by activated macrophages, is also involved in the activation of HIV infection through similar mechanisms. TNF-mediated cytotoxicity of cells exposed to this substance is related to the generation of intracellular hydroxyl radicals. An indirect argument in favor of the role of oxidative stress in HIV-associated disease progression is the consumption of glutathione (GSH), a major intracellular antioxidant, during HIV infection and progression. GSH is known to play a major role in regulation of T cell immune functions. Oxidative stress may also play an important role in the genesis of cellular DNA damage and, in this context, may be related to HIV-associated malignancies and disease progression. Finally, the role of antioxidants as components of therapeutic strategies to combat HIV disease progression is discussed.
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PMID:The role of oxidative stress in disease progression in individuals infected by the human immunodeficiency virus. 164 Jan 66


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