Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0021051 (immunodeficiency)
 71,517 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We investigated monocyte-derived macrophage function in 25 HIV-positive patients, 19 in the CDC class III and 6 class IV; 17 were intravenous drug abusers (IVDA) and 8 were homosexual men. Macrophages from HIV-positive patients behaved normally in assays of superoxide anion (O2-) production and candidacidal activity. After 3 days' treatment with 200 U/ml recombinant interferon-gamma (rIFN-gamma) or 250 U/ml recombinant granulocyte/macrophage-colony stimulating factor (rGM-CSF), both control and HIV-positive patients' phagocytes expressed the activated state, as indicated by the increased O2- production in response to phagocytable or soluble stimuli; however, these cytokines did not enhance candidacidal activity. Compared to appropriate HIV-negative controls (18 healthy heterosexuals, 4 homosexuals and 4 IVDA), macrophages from 19 of the 25 HIV-positive patients presented a significant defect in their Fc receptor (FcR)-dependent phagocytosis, independently from the CDC stage, AZT therapy, or life style. Treatment of macrophages with rIFN-gamma impaired their capacity to ingest IgG-coated erythrocytes, both in controls and HIV-positive subjects. Treatment of phagocytes with rGM-CSF significantly increased their FcR-dependent phagocytosis in controls, whereas in HIV-positive patients and in HIV-negative homosexuals and IVDA only an upward tendency was observed. Although the mechanism of the impaired FcR-dependent phagocytosis in HIV-positive patients remain to be clarified, our results suggest that this functional defect may be secondary to phagocyte priming by circulating IFN-gamma in vivo. This macrophage alteration may be implicated in the immunodeficiency of HIV-positive patients. However, considering the potential role of FcRs in HIV infection enhancement, the defective FcR function might even be a protective mechanism against FcR-mediated HIV dissemination. In the light of these findings, the immunotherapeutic potential of IFN-gamma and GM-CSF in HIV infection merits further investigation.
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PMID:Monocyte-derived macrophage function in HIV-infected subjects: in vitro modulation by rIFN-gamma and rGM-CSF. 173 Jan 55

4'-Azidothymidine (ADRT) is a novel nucleoside analog, that selectively inhibits human immunodeficiency virus replication in human lymphocytes. Unlike the dideoxyribonucleoside analogs and 3'-azido-2',3'-dideoxythymidine (AZT), ADRT retains the 3'-hydroxy group. The pathways of ADRT metabolism were elucidated by determining: (i) the kinetics of the interactions of ADRT and its metabolites with enzymes of thymidine metabolic pathways, (ii) the pool sizes of phosphorylated metabolites, and (iii) the nature of ADRT incorporation into human DNA. ADRT is not a substrate for thymidine phosphorylase, but is metabolized by kinases. Thymidine kinase phosphorylates ADRT to ADRT monophosphate (ADRT-MP). For this enzyme, ADRT has a Ki value of 5.2 microM, in comparison to a Km value of 0.7 microM for thymidine. The Km value of ADRT toward thymidine kinase is 8.3 microM and the rate of ADRT phosphorylation is 1.4% that of thymidine phosphorylation. ADRT-MP has a low affinity toward thymidylate kinase (a Ki value of 28.9 microM versus a Km value of 0.56 microM for thymidylate), and toward thymidylate synthase (a Ki value of 180 microM versus a Km value of 8 microM for deoxyuridylate). The results suggest that ADRT can be activated effectively by cellular kinases without significant interference of normal thymidine metabolism. In cultured human lymphocytes (A3.01, H9, and U937 cells), ADRT was phosphorylated efficiently to ADRT 5'-triphosphate (ADRT-TP), which is the major metabolite of ADRT. The intracellular concentrations of ADRT-TP ranged from 1 to 3.3 microM after 24 h of incubation with 2 microM of ADRT and the half-life of ADRT-TP varied from 3 to 6 h. Although ADRT-TP is a poor competitive inhibitor against dTTP toward DNA polymerases alpha and beta with Ki values of 62.5 and 150 microM, respectively. ADRT-MP was found to be internally incorporated into cellular DNA. The extent of ADRT-MP substitution for dTMP in DNA was 1 in 6979 for A3.01 cells incubated with 2.9 microM ADRT for 24 h. Internal incorporation of ADRT-MP contrasts with the mechanism of other 2',3'-dideoxynucleoside analogs (i.e. AZT, ddC, ddI, d4T...), which are DNA chain terminators. This finding indicates that a 3'-deoxy structure in a nucleoside analog is not a prerequisite for anti-human immunodeficiency virus activity.
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PMID:Metabolism of 4'-azidothymidine. A compound with potent and selective activity against the human immunodeficiency virus. 173 May 94

The federal government supports a nationwide network of medical centers to evaluate promising therapies against the human immunodeficiency virus (HIV) and the opportunistic infections and cancers that characterize AIDS. Forty-five obstetricians from the 49 medical centers receiving federal research support for the conduct of AIDS-related clinical trials, in preparation for a meeting, provided summary information about the number and clinical status of the known HIV-infected pregnant women under their care and the prenatal screening policies for HIV infection at their institutions. In the 12-month period before December 1989, an estimated 1000-1801 HIV-infected women delivered at these centers. The majority (82%) were asymptomatic, 12% were symptomatic, and 6% had AIDS. Routine T-cell testing of infected women was done as part of prenatal care in only 30 of 45 centers. Pneumocystis carinii pneumonia was reported in 35 women. Zidovudine was administered during pregnancy in 29 women. Formal prenatal screening policies have been implemented at the majority (43 of 45) of the medical centers. Most of the infected women identified at these centers chose to continue the pregnancy. With the increasing incidence of HIV infection in women, information concerning the clinical and immunologic state of pregnant infected women and the present use of antiretroviral and other related therapeutics during pregnancy can guide the approach to women's health care and is crucial to the design and implementation of AIDS clinical trials.
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PMID:Human immunodeficiency virus infection in pregnant women under care at AIDS clinical trials centers in the United States. 173 15

Azidothymidine (AZT) inhibits the replication of human immunodeficiency virus and it is the only drug so far licensed for treatment of acquired immunodeficiency syndrome (AIDS). A prerequisite for its antiviral activity is phosphorylation by cellular nucleoside kinases to the mono-, di-, and triphosphate levels. This study determined the capacity of isolated peripheral blood mononuclear cells (PBMC), resting or mitogen stimulated, from 36 different people of whom 5 were HIV+, to phosphorylate and accumulate intracellular AZT nucleotides. We found a large variation in the amount of products formed between PBMC treated at different times from the same individual as well as between the PBMC from different individuals. Resting PBMC showed the largest interindividual variation and their levels of AZT nucleotides were about 60-150-fold lower than in activated PBMC. The intracellular half lives of azidothymidine mono-, di-, and triphosphates, constituting, on the average, 96-99.2, 0.7-1.8, and 0.4-2.7% of total nucleotides at 0.08-1.6 microM AZT, respectively, were also determined. In mitogen-stimulated PBMC it was approximately 2.5 +/- 0.6 h for all the azidothymidine metabolites. The half-life for intracellular azidothymidine monophosphate in resting PBMC from two individuals was determined to 1.5 +/- 0.2 h. There appeared to be no significant difference in the AZT metabolism in PBMC from HIV-positive or-negative persons. A relative decrease in the intracellular formation of AZTDP and AZTTP from AZTMP was observed at concentrations of AZTMP above 1 microM. This fact may explain why lowering the doses of AZT still gives therapeutically efficient levels of the active metabolite AZTTP.
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PMID:Intracellular metabolism of 3'-azidothymidine in isolated human peripheral blood mononuclear cells. 174 82

To evaluate the effect of recombinant granulocyte-macrophage colony-stimulating factor (GM-CSF) on patients with acquired immunodeficiency syndrome (AIDS) or AIDS-related complex (ARC) who were intolerant to zidovudine because of neutropenia, we performed a randomized, open-label study in which patients were assigned to one of two groups. Zidovudine was discontinued in group A patients before instituting GM-CSF treatment and was restarted in a graduated fashion over 4 weeks. Group B patients continued on full-dose (1,200 mg/d) zidovudine therapy while beginning GM-CSF therapy. A total of 17 patients were entered, eight in group A and nine in group B. Five of eight patients in group A and seven of nine in group B had a history of Pneumocystis carinii pneumonia (PCP). All were homosexual males, except one female in group A who was the sex partner of a bisexual male with AIDS. All patients had neutropenia (absolute neutrophil count [ANC] less than 1,000/microL) while taking full-dose zidovudine. The mean CD4 (+/- SD) lymphocyte level was 37 (+/- 29)/microL and 39 (+/- 44)/microL in groups A and B, respectively. After randomization, patients were begun on subcutaneous GM-CSF at a dose of 1.0 microgram/kg/d. Patients in group A received 2 weeks of daily GM-CSF, at which time zidovudine was restarted if the ANC was greater than 1,000/microL; if the ANC was less than 1,000/microL, the dose of GM-CSF was increased to 3.0 micrograms/kg, and at 2-week intervals either zidovudine was restarted or the dose of GM-CSF was increased to 5 micrograms/kg and then 10 micrograms/kg, to maintain the ANC greater than 1,000/microL. Group B patients received full-dose zidovudine concurrently with GM-CSF administration. The dose of GM-CSF was increased every 2 weeks if necessary to keep the ANC greater than 1,000/microL while maintaining full-dose zidovudine therapy. Patients in each group showed an increase in total white blood cell (WBC) count. Neutrophils and eosinophils were responsible for the majority of this increase. Patients in group A had a more rapid increase in WBC than those in group B; however, by week 8, the WBC in each group was essentially equal. Viral replication as measured by human immunodeficiency virus (HIV) p24 antigen (Ag) was decreased in four patients in each group, increased in one patient in each group, and remained unchanged in the remainder. The ability to culture virus from peripheral blood mononuclear cells was not changed by the regimen. The major toxicities of the regimen were fever and malaise.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Recombinant human granulocyte-macrophage colony-stimulating factor ameliorates zidovudine-induced neutropenia in patients with acquired immunodeficiency syndrome (AIDS)/AIDS-related complex. 174 82

Electron microscopic features of muscle biopsies from 13 human immunodeficiency (HIV)-positive patients who had myopathy while receiving zidovudine (AZT) were compared with biopsies from five patients with HIV-induced myopathy who were not treated with AZT. All specimens showed disorganization of the myofibrillar structures, along with a varying degree of nemaline (rod) bodies, vacuolization, inflammation, and endothelial tubuloreticular profiles. One untreated and all AZT-treated patients had cytoplasmic bodies, which in the latter were abundant, large, and irregular. Two untreated patients had a peculiar osmiophilic destruction of the muscle fibers, with numerous tubuloreticular profiles in the endothelial cells and brisk inflammation that included lymphoplasmatoid cells. The AZT-treated group had ubiquitous abnormal mitochondria that complemented the presence of ragged red fibers seen by light microscopy. There was subsarcolemmal proliferation of mitochondria, with marked variation in size and shape and proliferation or disorganization of their cristae. Paracrystalline inclusions were seen in one patient. Blind re-examination of the electron micrographs showed abnormal mitochondria that readily distinguished patients with AZT-associated myopathy from those with untreated HIV-induced myopathy. Immunocytochemistry using antibodies to single- and double-stranded DNA revealed severe reduction of mitochondrial DNA compared with the normal nuclear DNA. Although the myopathies associated with HIV and AZT share common myopathologic features, the mitochondrial abnormalities are unique to the AZT-treated patients. Since mitochondrial DNA is specifically reduced, the structural changes noted on electron microscopy are probably associated with mitochondrial dysfunction. Zidovudine, a DNA chain terminator that inhibits the mitochondrial gamma-DNA polymerase, is toxic to muscle mitochondria.
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PMID:Ultrastructural characteristics and DNA immunocytochemistry in human immunodeficiency virus and zidovudine-associated myopathies. 174 34

To examine the mechanism of mitochondrial myocytotoxicity caused by long-term administration of zidovudine (AZT) in human immunodeficiency virus-positive patients, we examined the effect of AZT in vitro on human muscle in tissue culture and in vivo in rats treated with daily intraperitoneal injections of AZT at doses equivalent to the total daily dose used in acquired immunodeficiency syndrome patients. After 19 days, the AZT-treated myotubes in tissue culture exhibited abnormal mitochondria characterized by proliferation (mean +/- SD, 27.5 +/- 8 mitochondria/16 microns2 surface area, compared with 12.8 +/- 4 in the control cultures (p less than 0.001], enlarged size, abnormal cristae and electron-dense deposits in their matrix. The changes were partially reversible after AZT withdrawal. Rats treated with AZT developed weight loss, 100-fold elevation of creatine kinase, and increased serum lactate and glucose. In tissues, AZT had its highest concentration in the skeletal muscle and the heart. Skeletal and heart muscles from the treated animals, but not the controls, showed enlarged mitochondria with disorganized or absent cristae and electron-dense deposits in their matrix. Study of the mitochondrial functions assessed by evaluating stimulated oxygen consumption rate, enzymatic activities of electron transport chain and coupling state of oxidative phosphorylation (respiratory control ratio) revealed a decrease in rotenone-sensitive NADH cytochrome C reductase (complex I + III) and an uncoupling effect demonstrated by decreased respiratory control ratio. We conclude that AZT, a DNA chain terminator, is a muscle mitochondrial toxin that affects the oxidation-phosphorylation coupling and the activity of complex I and III of the mitochondrial respiratory chain.
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PMID:Abnormal skeletal and cardiac muscle mitochondria induced by zidovudine (AZT) in human muscle in vitro and in an animal model. 175 16

The combination of S-dC28 (a phosphorothioate oligodeoxcytidine 28 mer) with AZT, recombinant interferon alpha-A (IFN-alpha A) or dextran sulfate (DS) against replication of human immunodeficiency virus type 1 (HIV-1) were studied in MT4 cells, using both p24 core antigen and reverse transcriptase (RT) assays. Under the standardized conditions, the anti-HIV-1 dose-effect relationships of all test drugs showed sigmoidal curves with the following EC50 values: for the p24 core antigen assay, S-dC28, 0.03 microM; AZT, 0.004 microM; IFN-alpha A, 9.2 U/ml; DS, 0.26 micrograms/ml; for the RT assay, S-dC28, 0.04 microM; AZT, 0.01 microM; IFN-alpha A, 11.6 U/ml; and DS, 0.31 micrograms/ml. A computer software based on the median-effect principle and isobologram techniques were used to quantitatively analyze drug interactions by calculating the combination index (CI) where CI less than 1, = 1, and greater than 1 indicates synergism, additive effect and antagonism, respectively. For p24-ELISA, the interaction of S-dC28 and AZT in combination produced a slight antagonism on HIV-1 replicative inhibition with CI values of 1.29-1.10; for RT assays, at EC50-EC95 levels, the CI values are 1.96-1.11. For p24 core antigen assay, the combination of S-dC28 with IFN-alpha A exhibited a dose-dependent anti-HIV synergism with CI values of 1.15-0.87 at EC75-EC95 levels. The RT assays for the same combination showed a broad synergistic effect with CI values of 0.62-0.60, at EC50-EC95 levels. S-dC28 plus DS showed a nearly additive effect based on both assay methods.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Differential alteration of the anti-HIV-1 effect of phosphorothioate oligonucleotide S-dC28 by AZT, interferon-alpha, and dextran sulfate. 176 Feb 31

Zidovudine (ZDV) elicits its antiviral effect through intracellular metabolism to the 5'-triphosphate, which interferes with viral replication. Monitoring of the active metabolites of ZDV in cells could lead to an intracellular therapeutic range. This study was performed to determine whether a radioimmunoassay, previously used for in vitro quantitation of total phosphorylated ZDV inside peripheral blood leukocytes, could be used for similar determinations in patient samples. The relationship between ZDV dose, plasma concentrations, and intracellular metabolite concentrations was also examined. Ten-milliliter blood samples were drawn from each of 13 human immunodeficiency virus-infected patients and were assayed. Intracellular concentrations of phosphorylated ZDV ranged from 0.33 to 3.54 pmol/10(6) cells, similar to those observed in vitro. Phosphorylated ZDV was independent of dose, and did not correlate with plasma concentrations. Intracellular concentration in the patient population as a whole did not change during the 4-h dosing interval, while plasma concentration decayed normally. Later determinations in the same patients gave intracellular values within 31% of earlier values. Intraassay variability was less than 10%. Thus, the method is valid for measurement of phosphorylated ZDV in patient cells. Although individual concentrations showed no clear change during the 3-month study period, intracellular concentrations decreased with increasing length of therapy (up to 3 years) in the population as a whole. This suggests a decreased cellular ability to phosphorylate ZDV after prolonged exposure to drug. The lack of intracellular decay implies a half-life longer than the 1-h half-life of plasma ZDV. These data suggest that smaller doses or longer dosing intervals might maintain intracellular concentrations once steady state is achieved.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Concentrations of phosphorylated zidovudine (ZDV) in patient leukocytes do not correlate with ZDV dose or plasma concentrations. 178 Sep 65

Pharmacokinetics of zidovudine (azidothymidine, AZT) were investigated after oral administration (300 mg every 8 hours) in a human immunodeficiency virus seropositive patient who was also treated with plasma exchange (60 ml/kg). Plasma AZT concentrations were measured using high performance liquid chromatography assay. Plasma exchange clearances reached 1-3.8% of the total clearance. The fraction of AZT removed from separated plasma accounted for only 1% of the administered dose. The contribution of plasma exchange to the elimination of AZT appears to be negligible. Solely on the basis of AZT pharmacokinetic data, no particular dose adjustment appears to be necessary in patients treated with multiple plasma exchanges.
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PMID:Zidovudine removal during plasma exchange. 178 32


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