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

Reactive oxygen species like hydrogen peroxide (H2O2) have been shown to serve as messengers in the induction of NF-kappa B and, hence, in the activation and replication of human immunodeficiency virus type 1 (HIV-1) in human cells. Several antioxidant compounds and iron chelators have been shown to interfere with both NF-kappa B and HIV-1 activation under oxidative stress. Because 2,3-dihydroxybenzoic acid (DHB) and its ethyl ester derivative (DHB-EE) are potent oral iron chelators, we started to investigate their effects on monocytes treated with increasing H2O2 concentrations. These two compounds exert important protective effects against the cytotoxic effect of H2O2 as 300 microM DHB or DHB-EE increased cell survival from 30 to 85%. The treatment of monocytes with increasing amounts of H2O2 (from 0 to 3 mM) leads to the nuclear induction of NF-kappa B which is dose dependently inhibited by both DHB and DHB-EE. Addition of ferric ions to DHB only partially restores the NF-kappa B induction by H2O2, while this effect is almost completely restored by ferric ion addition to DHB-EE. Using spin trapping coupled to electron spin resonance, we have demonstrated that DHB and, to a lesser extent, DHB-EE trapped hydroxyl radicals produced by H2O2 photolysis. These data demonstrate that small aromatic molecules harboring both iron-chelating and antioxidant properties like DHB and DHB-EE can effectively interfere with the deleterious effects of H2O2 in monocytes where iron overload can be observed in HIV-1-infected patients.
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PMID:NF-kappa B transcription factor activation by hydrogen peroxide can be decreased by 2,3-dihydroxybenzoic acid and its ethyl ester derivative. 763 30

alpha-Lipoic acid, which plays an essential role in mitochondrial dehydrogenase reactions, has recently gained considerable attention as an antioxidant. Lipoate, or its reduced form, dihydrolipoate, reacts with reactive oxygen species such as superoxide radicals, hydroxyl radicals, hypochlorous acid, peroxyl radicals, and singlet oxygen. It also protects membranes by interacting with vitamin C and glutathione, which may in turn recycle vitamin E. In addition to its antioxidant activities, dihydrolipoate may exert prooxidant actions through reduction of iron. alpha-Lipoic acid administration has been shown to be beneficial in a number of oxidative stress models such as ischemia-reperfusion injury, diabetes (both alpha-lipoic acid and dihydrolipoic acid exhibit hydrophobic binding to proteins such as albumin, which can prevent glycation reactions), cataract formation, HIV activation, neurodegeneration, and radiation injury. Furthermore, lipoate can function as a redox regulator of proteins such as myoglobin, prolactin, thioredoxin and NF-kappa B transcription factor. We review the properties of lipoate in terms of (1) reactions with reactive oxygen species; (2) interactions with other antioxidants; (3) beneficial effects in oxidative stress models or clinical conditions.
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PMID:alpha-Lipoic acid as a biological antioxidant. 764 94

A randomized, unblinded study compared aerosolized pentamidine, 300 mg every month, and dapsone, 50 mg/day, for secondary prophylaxis of pneumocystosis in 196 AIDS patients. The study was prematurely discontinued due to excess mortality in the dapsone group. After a mean follow-up of 13 +/- 6.4 months, 22 (21%) of 103 patients in the pentamidine group were dead compared with 39 (42%) of 93 receiving dapsone; the estimated mortality rates at 18 months were 24.6% and 53.1%, respectively (P < .003, log-rank test). A negative interaction was observed between zidovudine and dapsone (P < .049, interaction test of Cox model), and the mean CD4 cell count during the study was lower in the dapsone (49 +/- 61/mm3) than in the pentamidine group (83 +/- 88/mm3; P < .002, t test). The lower survival might also be related to the oxidative effect of dapsone or to the addition of iron protoxalate to dapsone in this study. These results suggest caution in using dapsone as long-term therapy in advanced human immunodeficiency virus infection, especially in those receiving zidovudine.
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PMID:Lower survival in AIDS patients receiving dapsone compared with aerosolized pentamidine for secondary prophylaxis of Pneumocystis carinii pneumonia. Study Group. 865 6

The ability of iron(II).bleomycin to mediate RNA degradation was further characterized. At micromolar concentrations, FeII.BLM was shown to effect cleavage of Escherichia coli tRNA(1His) and a Schizosaccharomyces pombe amber suppressor tRNA construct in an efficient fashion. In contrast, E. coli tRNA(Cys) and yeast mitochondrial tRNA(Asp) and tRNA(fMet) precursors were not substrates for FeII.BLM. Also shown to be a good substrate for cleavage by FeII.BLM was yeast 5S ribosomal RNA. Since HIV-1 reverse transcriptase mRNA has previously been shown to be degraded by Fe.BLM (Carter et al., 1990a), members of the three major classes of RNA have now been shown to undergo Fe.BLM-mediated strand scission. For each of the substrate RNAs, cleavage occurred at sites unique to that substrate. Although RNA cleavage occurred at numerous sequences, 5'-G-pyr-3' sites were prominent. Likewise, while cleavage was noted in regions anticipated to be double-stranded, as well as in single-stranded regions, a disproportionate number of cleavages were noted at the junction between single- and double-stranded regions. As found in earlier studies, RNA cleavage was much more selective than DNA cleavage. Further, when RNA cleavage was carried out in the presence of reagents such as Mg2+, spermidine, and NaCl, the selectivity of cleavage was further enhanced. The highly selective and efficient cleavage of a number of RNA molecules reinforces our earlier suggestion that RNA may constitute a therapeutically relevant target for bleomycin.
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PMID:Characterization of iron (II).bleomycin-mediated RNA strand scission. 768 45

The superimposition of human immunodeficiency virus (HIV) infection, associated opportunistic infections, and anti-retroviral therapy further worsens the severity of anemia in patients also suffering from end-stage renal disease. A major cause of anemia in renal failure is a deficiency of erythropoietin. The causes of anemia in HIV disease include direct and indirect stem cell inhibition by the virus, increased peripheral destruction of red blood cells, and bone marrow suppression by various opportunistic infections and therapeutic drugs, particularly zidovudine. We compared the efficacy of recombinant human erythropoietin (rHuEPO) therapy in improving the anemia in HIV-infected end-stage renal disease patients (group I) with that in nondiabetic (group II) and diabetic (group III) hemodialysis patients without HIV infection. All three groups of patients were comparable in dialysis prescription and serum iron studies. Iron supplementation was prescribed to all patients, and none received blood transfusions. After 8 weeks of rHuEPO therapy (administered intravenously in a dose of 100 U/kg body weight thrice weekly), the mean increase in hematocrit was similar in all responders (5.8% increase in hematocrit in 23 of 30 HIV patients and 6.7% increase in 24 of 30 non-HIV patients). Response in hematocrit was noted in HIV patients despite the presence of opportunistic infections in 15 and zidovudine administration in 11. Seven HIV-positive patients and six non-HIV patients failed to respond to rHuEPO. Irrespective of the HIV status, the baseline serum EPO levels in patients responding to rHuEPO were significantly lower than those in nonresponders.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The efficacy of erythropoietin in human immunodeficiency virus-infected end-stage renal disease patients treated by maintenance hemodialysis. 777 87

Anemia is an important cause of morbidity and probably mortality in patients with acute Plasmodium falciparum infection. The authors investigated the association between P. falciparum malaria and anemia in children living in holoendemic malaria areas in their population-based study of 338 children aged 6-40 months living in the Bagamoyo area of Tanzania. The study was conducted from late May to October 1992 when malaria transmission is high in coastal Tanzania. The children were selected at random from seven villages in the study area and not on the basis of a history of illness, suspected malaria, or any other health reason. All children were examined by a physician and detailed medical histories were taken. At enrollment, 2.5% of the children were severely anemic and 74.1% were anemic. With treatment and active surveillance, the incidence of severe anemia dropped to 1.4% and anemia to 69.5%. Stepwise regression analysis found fever and parasitemia to effectively predict anemia and that the anemic condition was age dependent. The majority of children infected with P. falciparum were iron deficient, followed by normochromic macrocytic anemias, with strong evidence that the anemia was associated with malaria and not geohelminth infection. The authors consider the importance of malaria and anemia as a cause of childhood morbidity in Africa and comment on the realization that blood transfusions commonly used to treat severe anemia are a major vehicle for HIV transmission.
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PMID:Anaemia and Plasmodium falciparum infections among young children in an holoendemic area, Bagamoyo, Tanzania. 778 26

Noncoding sequences regulate the function of mRNA and DNA. In animal mRNAs, iron responsive elements (IREs) regulate the synthesis of proteins for iron storage, uptake and red cell heme formation. Folding of the IRE was indicated previously by reactivity with chemical and enzymatic probes. 1H- and 31P-NMR spectra now confirm the IRE folding; an atypical 31P-spectrum, differential accessibility of imino protons to solvents, multiple long-range NOEs and heat stable subdomains were observed. Biphasic hyperchromic transitions occurred (52 and 73 degrees C). A G-C base pair occurs in the hairpin loop (HL) (based on dimethylsulfate, RNAse T1 previously used, and changes in NMR imino proton resonances typical of G-C base pairs after G/A substitution). Mutation of the hairpin loop also decreased temperature stability and changed the 31P-NMR spectrum; regulation and protein (IRP) binding were previously shown to change. Alteration of IRE structure shown by NMR spectroscopy, occurred at temperatures used in studies of IRE function, explaining loss of IRP binding. The effect of the HL mutation on the IRE emphasizes the importance of HL structure in other mRNAs, viral RNAs (e.g. HIV-TAR), and ribozymes.
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PMID:The importance of a single G in the hairpin loop of the iron responsive element (IRE) in ferritin mRNA for structure: an NMR spectroscopy study. 787 May 79

The prevelance of IDA in industrialized countries has declined in recent decades, but there has been little change in the worldwide prevalence. IDA is currently estimated to affect more than 500 million people. Recent studies have indicated that anemia per se, the most common manifestation of iron deficiency, is less important from a public health standpoint than liabilities associated with tissue iron deficiency. The most important of the latter are an impairment in psychomotor development and cognitive function in infants and preschoolers, a deficit in work performance in adults, and an increase in the frequency of low birth weight, prematurity, and perinatal mortality in pregnancy. There have been several recent advances in combatting nutritional iron deficiency. One of the major problems has been in distinguishing iron deficiency from other causes of anemia seen epidemiologically such as malaria, HIV infection, chronic inflammation, hemoglobinopathies, and protein energy malnutrition. When combined with serum ferritin and hemoglobin determinations, the serum transferrin receptor assay is a valuable addition in epidemiologic surveys because it provides a quantitative measure of functional iron deficiency and it distinguishes true IDA from the anemia of chronic disease. The most difficult challenge is to develop effective methods of supplying iron to large segments of a population. Supplementation with iron tablets is suitable for only brief periods of need such as during pregnancy. The poor compliance with existing supplementation programs is believed to be due mainly to the gastrointestinal side effects of oral iron which can be eliminated by the use of a gastric delivery system. The most effective long-term strategy is to increase the intake of bioavailable iron in the diet. The customary approach has been to fortify a food staple such as wheat, rice, sugar, or salt, and thereby increase the iron intake of the entire population. However, because of concerns about the risk of cancer and heart disease in individuals with high iron stores, there is an increasing reluctance to supply iron to individuals who do not require it. A more effective strategy is to fortify food vehicles that are targeted to segments of the population at greatest risk of iron deficiency such as infants and school children. Because of the strong inhibitory properties of diets in regions of the world where iron deficiency is most prevalent, the use of NaFeEDTA has important advantages for food fortification.
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PMID:Iron deficiency: the global perspective. 788 26

Skeletal muscle involvement may occur at all stages of human immunodeficiency virus (HIV)-infection, and represents the first manifestation of the disease in some patients. There have been many controversies about the classification of myopathies related to HIV infection. We usually classify muscle involvement in HIV-infected patients in one of the following categories: (1) HIV-associated myopathy, a myopathy that meets the criteria for polymyositis in a majority of patients, and those for acquired nemaline myopathy in some; (2) zidovudine myopathy, a reversible mitochondrial myopathy; (3) the HIV-wasting syndrome and other AIDS-associated cachexias; (4) opportunistic infections and tumoral infiltrations of skeletal muscle; (5) vasculitic processes and iron pigment deposits. Immunohistology for major histocompatibility complex class I antigen and the histochemical reaction for cytochrome C oxidase are helpful in correctly classifying a myopathy as HIV polymyositis or zidovudine myopathy respectively. Studies of circulating levels and tissue expression of cytokines in HIV-infected patients have yielded new insights into the pathogenesis of the various AIDS-associated muscle disorders.
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PMID:Skeletal muscle involvement in HIV-infected patients. 793 72

Expression of the structural proteins of the human immunodeficiency virus type 1 (HIV-1), the human T-cell leukemia virus type I (HTLV-I), and of the transferrin receptor (TfR) mRNA depends on posttranscriptional regulatory mechanisms involving both positive and negative elements. In these systems the presence of elements decreasing mRNA expression have been demonstrated. The regulatory proteins (Rev, Rex or iron response element binding protein IRE-BP) antagonize the effects of the downregulatory elements by interacting directly with specific mRNA sites (Rev responsive element, RRE, Rex responsive element, RXRE, or iron responsive elements, IREs) resulting in stabilization and efficient expression of the corresponding mRNAs. To investigate whether this strategy involves common pathways of mRNA utilization, we have studied expression from hybrid mRNAs that contained these previously identified HIV-1 or TfR instability determinants and the binding sites of the regulatory proteins Rev, Rex and/or IRE-BP. Our results demonstrate that only low levels of these hybrid mRNAs accumulate in the absence of the positive regulatory factors Rev, Rex or IRE-BP. The presence of these factors counteracts the effect of heterologous downregulatory elements resulting in increased accumulation of the hybrid mRNAs. However, while Rev or Rex regulation also resulted in efficient protein expression, the IRE-BP only affected mRNA levels without significantly affecting protein expression, suggesting that the pathways of mRNA stabilization/expression are different in these systems.
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PMID:Rev of human immunodeficiency virus and Rex of the human T-cell leukemia virus type I can counteract an mRNA downregulatory element of the transferrin receptor mRNA. 798 24


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