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)

Quinolinic acid (QUIN) is an neurotoxic N-methyl-D-aspartate receptor agonist and an L-tryptophan metabolite of the kynurenine pathway. Increased concentrations of QUIN occur in both cerebrospinal fluid (CSF) and blood of patients infected with human immunodeficiency virus (HIV)-1, particularly those with neurologic disturbances. In the present study of HIV-1 infected patients in Walter Reed stages 4, 5 and 6, reductions in L-tryptophan accompanied proportional increases in L-kynurenine and QUIN in both serum and CSF. Further, close inter-correlations exist between QUIN kynurenic acid and L-kynurenine with both beta 2-microglobulin and neopterin in CSF and serum. These correlations support the hypotheses that the kynurenine pathway is activated in association with inflammation and induction of indoleamine-2,3-dioxygenase. There were no relationships between CSF QUIN, L-kynurenine or kynurenic acid with the ratio of serum:CSF albumin concentrations, which indicates that the increases in CSF QUIN, L-kynurenine or kynurenic acid were not dependent on a breakdown of the blood-brain barrier. Kynurenic acid is also a kynurenine pathway metabolite that can attenuate the excitotoxic effects of QUIN when present in higher molar concentrations. While CSF kynurenic acid levels were increased in HIV-1-infected patients, the magnitude of the increases were smaller than those of QUIN and the molar concentrations of kynurenic acid were consistently lower than QUIN by at least one order of magnitude. We conclude that immune activation increases the levels of neuroactive kynurenines within the central nervous system of HIV-1-infected patients secondary to activation of indoleamine-2,3-dioxygenase.
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PMID:Inter-relationships between quinolinic acid, neuroactive kynurenines, neopterin and beta 2-microglobulin in cerebrospinal fluid and serum of HIV-1-infected patients. 138 55

We have shown that the interaction of pepstatin A with human immunodeficiency virus-1 protease (HIV-1 protease) can be characterized by a high-affinity mode (Ki = 478 +/- 27 nM), resulting in pure competitive inhibition of the hydrolytic activity of HIV-1 protease toward the fluorogenic substrate. Binding of pepstatin in this mode induces a blue shift in the endogenous fluorescence arising from the tryptophan residues in HIV-1 protease. This shift is maximal in the presence of 10 microM pepstatin. Haloperidol, in contrast, interacts with HIV-1 protease with weaker affinity (Ki = 19 +/- 1 microM) in a mode which results in pure noncompetitive inhibition of the hydrolytic activity of HIV-1 protease. Binding of haloperidol in this mode induces a red shift in the endogenous fluorescence arising from the tryptophan residues in HIV-1 protease. This shift is maximal in the presence of 200 microM haloperidol. Addition of both pepstatin and haloperidol at concentrations in the range of their Ki values results in additive inhibition of the hydrolytic activity of HIV-1 protease, as well as an additive effect on the tryptophan fluorescence of protease. However, at saturating concentrations of pepstatin and haloperidol, the effect of haloperidol was predominant, as measured by the changes in the intrinsic fluorescence of HIV-1 protease.
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PMID:Inhibitors of human immunodeficiency virus-1 protease. 149 58

Increased concentrations of the excitotoxin quinolinic acid (QUIN) have been implicated in the neurologic deficits and brain atrophy that may accompany infection with the human immunodeficiency virus type-1. Key neuropathologic features of the AIDS encephalitis are replicated in some macaques following infection with the simian immunodeficiency virus (SIV). In the present studies, cerebrospinal fluid (CSF) QUIN concentrations increased within 2 weeks following infection of 11 rhesus macaques (Macaca mulatta) with a neurotropic sooty mangabey isolate of the simian immunodeficiency virus (SIVsm) and were sustained to greater than 2 standard deviations above uninfected control macaques. Highest CSF QUIN concentrations (up to 400-fold above pre-inoculation levels) were observed in 6 SIVsm-infected macaques with motor and behavioral abnormalities during life, brain atrophy on MRI scan and inflammatory lesions within the brain and meninges. Four of the 6 neurologic macaques deteriorated rapidly within 12 weeks after inoculation and had substantially larger increases in CSF QUIN levels than 2 other neurologic macaques and 5 macaques without neurologic signs which survived for longer than 37 weeks. Increases in serum QUIN and CSF kynurenic acid also occurred but generally to a lesser degree than the increases in CSF QUIN. In some animals, increases in serum L-kynurenine concentrations and reductions in CSF and serum L-tryptophan occurred and were consistent with activation of indoleamine-2, 3-dioxygenase, the first enzyme of the kynurenine pathway in extrahepatic tissues. CSF QUIN exceeded serum QUIN in 8.8% of samples from macaques with neurologic signs, supporting increased QUIN synthesis within the central nervous system. Production of [13C6]QUIN was demonstrated in one SIVsm-infected macaque and one uninfected control macaque following an intracisternal injection of [13C6]L-tryptophan and suggests that L-tryptophan is a substrate for QUIN synthesis within the nervous system or meninges, although the cellular localization of QUIN synthesis remain to be determined. We conclude that increases in kynurenine pathway metabolism occur in SIV-infected macaques and are most prominent in macaques with neurologic signs. Macaques infected with SIV offer a model to investigate the relationship between the metabolism of neuroactive kynurenines and neurologic disturbances associated with retroviral infection.
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PMID:Relationship of neurologic status in macaques infected with the simian immunodeficiency virus to cerebrospinal fluid quinolinic acid and kynurenic acid. 153 32

The handle region (residues 84-99) in ribonuclease HI (RNase HI) from Escherichia coli, which is rich in basic amino acid residues, was altered by alanine-scanning mutagenesis. Fifteen mutant proteins were purified to homogeneity and analyzed for the enzymatic activity. A mutation of either of 2 tryptophan residues at 85 or 90 resulted in a large increase in the Km value along with a large decrease in the Vmax value. These values probably resulted from conformational changes introduced by the mutations as indicated by the CD spectra of these mutant proteins. All other mutant enzymes had Vmax values similar to that of the wild-type enzyme. In contrast, replacement of any basic amino acid residue in the handle region, except for lysine 86, yielded proteins whose Km values were 3-5-fold higher than the wild-type enzyme. Such effects were shown to be cumulative, suggesting strongly that the cluster of positive charges in the handle region is important for the effective binding of the substrate. Interestingly, the region of human immunodeficiency virus reverse transcriptase with homology to E. coli RNase HI lacks the handle region which may account for the poor RNase H activity of the domain when separated from the polymerase domain.
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PMID:Importance of the positive charge cluster in Escherichia coli ribonuclease HI for the effective binding of the substrate. 164 12

Nocturnal sleep was studied in 14 human immunodeficiency virus (HIV)-positive patients without opportunistic infections of the central nervous system. Seven patients had no bodily complaints at the time of the investigation. Patients exhibited an impaired nocturnal sleep with longer sleep onset latency, reduced total sleep time, reduced sleep efficiency, and more time spent awake and in stage 1. Stage 2 sleep was significantly decreased; in 2 cases, sleep spindle density was extremely low. REM latency was reduced and correlated negatively with depressive symptomatology, while the percentages of REM and slow wave sleep were normal. No significant differences in sleep parameters were present among patients in different stages of the illness, or between patients with and without bodily complaints. Ventricular size and sulcal width on computed tomography scans correlated with sleep variables indicating reduced sleep quality, and with REM density. Decreased tryptophan plasma levels were associated with shorter and less efficient sleep, and with reduced stage 2 sleep. The findings demonstrate that sleep EEG investigations can be valuable for detecting and monitoring central nervous system affection in HIV-positive individuals.
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PMID:Nocturnal sleep EEG in patients with HIV infection. 182

Reduced tryptophan and increased kynurenine concentrations have been reported in patients with human immunodeficiency virus type 1 (HIV-1) infection. From in vitro data it appears that activated indoleamine 2,3-dioxygenase (IDO) is involved in this metabolic change. IDO is inducible by interferon-(IFN)-gamma. We compared serum concentrations of IFN-gamma and neopterin (the biosynthesis of which is also inducible by IFN-gamma) with serum, tryptophan and kynurenine of 42 patients with HIV-1 infection. IFN-gamma, neopterin and kynurenine levels were significantly increased compared to HIV-1 seronegative controls whereas tryptophan was significantly decreased. Various significant correlations were found between tryptophan, kynurenine, IFN-gamma and neopterin concentrations. Highest degree of correlation was found between neopterin, IFN-gamma and the kynurenine per tryptophan quotient which is the ratio between the product and the substrate concentration of IDO. The data indicate that decreased tryptophan in HIV-1 seropositives may result from chronic immune activation and can be referred to increased activation of IDO.
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PMID:Increased endogenous interferon-gamma and neopterin correlate with increased degradation of tryptophan in human immunodeficiency virus type 1 infection. 190 3

We have examined genetic variation of the simian immunodeficiency virus (SIV) in four macaques inoculated with virions derived from molecular clones of proviral DNA. Our data demonstrated that the SIV genome is capable of rapid and extensive genetic variation. This variation was especially large in the env gene, where nucleotide substitution frequencies were as high as 10(-1)/site/year. In some env clones, a high G to A transition rate was observed that accounted for up to 79% of the observed nucleotide substitutions. Moreover, in env clones with a high G to A transition rate, multiple in-frame stop codons were generated exclusively at tryptophan codons. Another interesting observation was the lack of variation in the region analogous to the V3 loop in the HIV-1 Env protein. Considered together, these data have important implications for studies of pathogenesis and vaccine development in the SIV model system.
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PMID:The genetic fate of molecularly cloned simian immunodeficiency virus in experimentally infected macaques. 192 74

We compared tryptophan, neopterin, and interferon-gamma (IFN-gamma) concentrations in serum and cerebrospinal fluid (CSF) of 22 patients with human immunodeficiency virus type 1 (HIV-1) infection. Tryptophan levels were found to be decreased in CSF and serum of patients whereas neopterin levels in CSF and serum and serum IFN-gamma concentrations were increased compared to healthy HIV-1 seronegatives. Tryptophan concentrations correlated negatively to neopterin concentrations, and serum neopterin concentrations correlated positively to IFN-gamma concentrations. Thus, decrease of tryptophan levels is associated with chronic immune stimulation in patients with HIV-1 infection. From the data it appears that reduced tryptophan in patients may result from induction of indoleamine (2,3)-dioxygenase by IFN-gamma.
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PMID:Immune activation and decreased tryptophan in patients with HIV-1 infection. 212 2

Increased concentrations of excitotoxin quinolinic acid in cerebrospinal fluid (CSF) are associated with infection with the human immunodeficiency virus (HIV-1) and have been implicated in the pathogenesis of the acquired immune deficiency syndrome (AIDS) dementia complex. In the present study, inoculation of macaques with D/1/California, an immunosuppressive serotype 1 type D retrovirus, was associated with acute and chronic increases in CSF and serum quinolinic acid concentrations in macaques that had developed SAIDS, a simian disease analogous to AIDS in humans--particularly macaques with demonstrable opportunistic infections. Kynurenic acid, an antagonist of excitatory amino acid receptors as well as the excitotoxic effects of quinolinic acid, was also increased in the CSF of SAIDS macaques, but to a significantly lesser degree than was quinolinic acid (kynurenic acid, 1.8-fold; quinolinic acid, 15.6-fold). CSF quinolinic acid, but not kynurenic acid, was also increased in viremic macaques with SAIDS-related complex (2.4-fold) and asymptomatic virus positive carriers (3.4-fold). Macaques that had recovered from D/1/California infection and were antibody positive and virus negative had normal CSF quinolinic acid and kynurenic acid concentrations. Increased activity of indoleamine-2,3-dioxygenase, the first enzyme of the kynurenine pathway, was indicated in the macaques with SAIDS by reduced serum L-tryptophan and elevated serum L-kynurenine concentrations. Macaques infected with D/1/California may provide a primate model for investigation of the mechanisms involved in increases in CSF quinolinic acid in retrovirus and other infectious diseases, including HIV-1. It remains to be determined whether the increased CSF quinolinic acid concentrations and the increased ratio of quinolinic acid to kynurenic acid have neurological significance or are a useful "marker" of infection.
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PMID:Increased ratio of quinolinic acid to kynurenic acid in cerebrospinal fluid of D retrovirus-infected rhesus macaques: relationship to clinical and viral status. 216 38

Recombinant Rev protein of human immunodeficiency virus type 1 has been expressed in Escherichia coli and purified by ion-exchange and gel-filtration chromatography. Specific binding of the purified protein to the Rev-responsive element of the viral RNA is demonstrated. Physical characterization of the purified protein by circular dichroism and intrinsic fluorescence spectroscopy indicate that the protein preparation is suitable for structural analysis. Circular dichroism measurements show that the protein is approximately 40-45% alpha-helix. Tryptophan fluorescence measurements suggest that the single tryptophan residue is located near the surface of the protein. Gel-filtration chromatography of the protein indicates that it has an apparent molecular mass of 33,000 daltons. This suggests that the protein in solution forms a stable tetramer consisting of monomers having molecular mass of 13,000 daltons.
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PMID:Purification and characterization of recombinant Rev protein of human immunodeficiency virus type 1. 221 89


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