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

Patients who are infected with human immunodeficiency virus type 1 (HIV-1) frequently present with neurological and psychiatric symptoms. Kynurenic acid (KYNA), an intermediate metabolite of L-kynurenine (L-KYN), is a neuroprotectant and a broad-spectrum antagonist at excitatory amino acid (EAA) receptors. The present study examines the biosynthetic machinery of KYNA in the frontal cortex and cerebellum of 25 HIV-1 and 16 control (CO) patients. We measured the contents of L-KYN and KYNA and the activity of enzymes synthesizing KYNA, kynurenine aminotransferases I and II (KAT I and KAT II). The KYNA level was significantly increased in the frontal cortex (209 +/- 38% of CO; p < 0.05) and moderately increased in the cerebellum (164 +/- 31% of CO) of HIV-1 brains as compared with controls. The bioprecursor of KYNA, L-KYN, was increased in frontal cortex (188 +/- 45% of CO) and cerebellum (151 +/- 16% of CO; p < 0.05). The elevated KYNA in frontal cortex correlated with significant increases of KAT I (341 +/- 95% of CO; p < 0.05) and KAT II (141 +/- 8% of CO; p < 0.05). In the cerebellum, a high KYNA content was in the line with increased KAT I (262 +/- 52% of CO; p < 0.05) activity, while KAT II was in a control range (85 +/- 12% of CO). This study demonstrates that HIV-1 infection associates with elevated KYNA synthesis in the brain. In contrast to KAT II, KAT I was prominently increased in both brain regions investigated. Differences in neurochemical parameters of KYNA metabolism between frontal cortex and cerebellum suggests selective tissue damage. Drugs which influence the synthesis of the endogenous neuroprotectant KYNA may become useful in the therapy of neuropsychiatric manifestations of HIV-1 infected patients.
 ...
PMID:Kynurenic acid metabolism in the brain of HIV-1 infected patients. 1112 2

Kynurenic acid, an intermediate metabolite of L-kynurenine, is a competitive antagonist of inotropic excitatory amino acid (EAA) receptors as well as a non competitive antagonist of 7 alpha nicotine cholinergic receptors and its involvement in memory deficit and cognition impairment has been suggested. Alterations of kynurenic acid metabolism in the brain after HIV-1 (human immunodeficiency virus type-1) infection have been demonstrated. The present study evaluates the biosynthetic machinery of kynurenic acid e.g. the content of L-kynurenine and kynurenic acid, as well as the activity of enzymes synthesizing kynurenic acid, kynurenine aminotransferase I (KAT I) and kynurenine aminotransferase II (KAT II) in the frontal cortex and cerebellum of HIV-1 infected patients in relation to different types of pathology classified as follows: HIV in brain (HIV); opportunistic infection (OPP); infarction of brain (INF); malignant lymphoma of brain (LY); and glial dystrophy (GD) and of control (CO) subjects. Of all investigated pathologies the most frequent was OPP (65%), followed by HIV (26%), LY, INF, and GD (each 22%, respectively). Further, 68% of HIV-1 patients had bronchopneumonia, the highest incidence of which, at 60%, was seen in the OPP and LY group. Kynurenic acid was increased significantly in the frontal cortex of LY (392% of CO, P < 0.001), HIV (231% of CO, P < 0.01) and GD (193% of CO, P < 0.05), as well as in the cerebellum of GD (261% of CO, P < 0.01). A significant increase of L-kynurenine was observed in the frontal cortex of LY (385% of CO, P < 0.001) and INF (206% of CO, P < 0.01), and in the cerebellum of GD, LY, OPP and HIV (between 177% and 147% of CO). The KAT I activity increased significantly in the frontal cortex of all pathological subgroups, ie OPP = 420% > INF > LY > HIV > GD = 192% of CO. In the cerebellum, too, all pathological subgroups showed marked increase of KAT I activity (OPP = 320% > LY, HIV > GD > INF = 176% of CO). On contrary, the activity of KAT II was moderately, but significantly, higher in the frontal cortex of INF and OPP; in the cerebellum of HIV, OPP and LY it was comparable to the control, while mildly reduced in INF and GD. Interestingly, normal subjects with the diagnosis of bronchopneumonia were characterized by high kynurenic acid metabolism in the brain, too. Correlation analyses between kynurenine parameters revealed association between high ratio KAT I/KAT II and increased kynurenic acid level and lower L-kynurenine in the frontal cortex and cerebellum of HIV and LY subgroups. The present study revealed a different pattern of alteration of kynurenic acid metabolism in frontal cortex and cerebellum among investigated pathological subgroups of HIV-1 infected patients. Interestingly, a marked enhancement of kynurenic acid metabolism in the brain has been found with occurrence of bronchopneumonia. This finding indicates a notable association between impaired conditions of oxygen availability and enhancement of kynurenic acid formation in the human brain. These observation(s) might have an impact on the understanding of pathological processes in the brain after HIV-1 infection involving the development of neuropsychiatric and neurological symptoms, including memory and cognition impairment.
 ...
PMID:Kynurenic Acid Metabolism in Various Types of Brain Pathology in HIV-1 Infected Patients. 2330 Mar 46