Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.6.1.1 (aspartate aminotransferase)
21,665 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have selected an HXB2 variant which can replicate in the presence of a neutralizing human serum. Sequencing of the gp120 region of the env gene from the variant and parental viruses identified a single amino acid substitution in the third conserved region of gp120 at residue 375 (AGT-->AAT, Ser-->Asn; designated 375 S/N). The escape mutant was found to be resistant to neutralization by soluble CD4 (sCD4) and four monoclonal antibodies (MAbs), 39.13g, 1.5e, G13, and 448, binding to epitopes overlapping that of the CD4 binding site (CD4 b.s.). Introduction of the 375 S/N mutation into HXB2 by site-directed mutagenesis confirmed that this mutation is responsible for the neutralization-resistant phenotype. Both sCD4 and three of the CD4 b.s. MAbs (39.13g, 1.5e, and G13) demonstrated reduced binding to the native 375 S/N mutant gp120. The ability to select for an escape variant resistant to multiple independent CD4 b.s. MAbs by a human serum confirms the reports that antibodies to the discontinuous CD4 b.s. are a major component of the group-specific neutralizing activity in human sera.
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PMID:Resistance of a human serum-selected human immunodeficiency virus type 1 escape mutant to neutralization by CD4 binding site monoclonal antibodies is conferred by a single amino acid change in gp120. 768 20

Chronic hepatitis due to putative non-A, non-B, non-C hepatitis occurring in an individual who is negative for HBV and HCV markers has been identifiable only recently. Little or nothing is known about its natural history or response to interferon therapy. In the present study, 13 subjects with chronic non-A, non-B, non-C hepatitis were treated with interferon for 6 months (5 million units, three times per week). Prior to and after 6 months of therapy and again 6 weeks after discontinuing interferon therapy, each subject underwent a liver biopsy. These tissues were used to define the histopathology, the character of the cellular infiltrate within the liver, and the changes in histopathology and inflammatory infiltrate achieved in response to interferon therapy and withdrawal. No differences for age, gender, initial AST, bilirubin, histopathology, or Knodell score were evident between responders (n = 7) and non-responders (n = 6). Only the number of NK cells was altered significantly as a result of IFN treatment and distinguished responders from non-responders. These data demonstrate that: (1) chronic non-A, non-B, non-hepatitis can be treated with interferon; (2) interferon activates NK cells and enhances hepatocyte expression of Class II MHC antigens; and (3) interferon also increases the number of CD3, CD4, and CD8 cells found within the liver but these changes do not distinguish between responders and non-responders.
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PMID:Treatment of putative non-A, non-B, non-C hepatitis with alpha interferon: a preliminary trial. 793 74

We have previously observed an increased frequency of liver failure in human immunodeficiency virus (HIV)-infected hemophiliacs. The purpose of this study was to quantitate hepatitis C virus (HCV) RNA levels in serial samples from HIV-seropositive (HIV+) and HIV-seronegative (HIV-) hemophiliacs before and after HIV seroconversion, and to examine the relationship of HCV RNA levels to CD4 cell counts and to hepatic dysfunction over time. HCV RNA levels were measured on serial samples of serum stored frozen from 17 HCV+/HIV+ and 17 HCV+/HIV- subjects matched within 5 years of their birth dates. All were HCV+ before study entry. HCV RNA levels were quantitated by a branched DNA-enhanced label amplification (bDNA) assay. For samples less than the cut off, HCV RNA was measured by the nested polymerase chain reaction. Individual changes over time, clinical groups, and mean values within predetermined time windows were compared with Wilcoxon rank sum tests. Mean HCV RNA levels increased from 2.76 (standard error [SE] 1.33) x 10(5) to 2.84 (SE 1.39) x 10(6) eq/mL during the first 2 years after HIV seroconversion (P = .006). Baseline HCV RNA levels in the pre-HIV seroconversion group were not significantly different from the baseline levels in those who remained HIV (P = .79). Over the entire period of study, HCV RNA levels increased nearly threefold in those who remained HIV- (mean 9.47 [SE 4.78] x 10(5) to 2.81 [SE 1.13] x 10(6)/mL; P = .02). Among those who became HIV+, HCV RNA levels increased 58-fold (mean 2.85 [SE 1.26] x 10(5) to 1.66 [SE 0.57] x 10(7) eq/mL; P = .0001). The rate of increase in HCV RNA levels was eightfold faster for HIV+ subjects than for subjects who remained HIV- (P = .009). HCV RNA levels increased twofold higher in 5 subjects who developed liver failure compared with the 12 who did not (P = .43). HCV RNA levels correlated significantly with CD4 counts (R = -.33, P = .01) and serum aspartate aminotransferase levels (AST) (R = .36, P = .007). We conclude that HCV RNA levels are significantly higher in HIV+ than in HIV- multitransfused hemophiliacs. HCV load increases over time, is enhanced by HIV, and further increases as immune deficiency progresses. HCV RNA levels are directly associated with high AST levels. These findings suggest that HIV-induced immune deficiency may promote increased HCV replication.
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PMID:Increasing hepatitis C virus RNA levels in hemophiliacs: relationship to human immunodeficiency virus infection and liver disease. Multicenter Hemophilia Cohort Study. 804 20

A distinct clinical syndrome of cholestasis and hepatitis occurred during early infancy in seven infants with perinatally acquired human immunodeficiency virus 1 infection. In five infants hepatitis was the first manifestation of human immunodeficiency virus 1 infection. The median age of onset of hepatitis was 7 months (range, 5 to 10 months). The mean total bilirubin concentration at presentation was 7.4 mg/dl (range, 3.9 to 11 mg/dl), the mean aspartate aminotransferase was 1512 IU/liter (range, 782 to 2960 IU/liter) and the mean alanine amino-transferase 512 IU/liter (range, 92 to 1247 IU/liter). The absolute CD4 count at the time of onset of hepatitis ranged from 191 to 2298 cells/mm3 (mean, 766 cells/mm3). Six of the seven children died within 12 weeks of onset of hepatitis, three as a result of complications of Pneumocystis carinii pneumonia, and two died of complications secondary to cytomegalovirus. In only one infant was the cause of death the direct consequence of liver failure. The seventh infant died 17 months after the onset of hepatitis of dilated cardiomyopathy. No specific etiologic agent has been identified as the cause of cholestatic hepatitis in these infants. In situ hybridization studies to detect human immunodeficiency virus 1 messenger RNA was negative in the liver tissue obtained at biopsy and autopsy in five of the samples tested.
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PMID:Cholestatic hepatitis in children infected with the human immunodeficiency virus. 810 98

The mechanism(s) of rejection or tolerance induction is a competitive, complex process that presumably involves interactions between multiple subpopulations of T lymphocytes. We investigated the roles of CD8+ cytolytic and CD4+ helper T cells in rat strains that tolerate liver allografts and that differ at both the major histocompatibility complex (MHC) (RT1) and minor histocompatibility genes. Orthotopic liver transplantation (OLT) with arterial reconstruction was performed with Brown Norway (BN) (RT1n) donors and Lewis (RT1(1)) recipients, some of which were untreated, others treated with anti-CD8 antibody, and still others treated with anti-CD4 antibody. Liver graft rejection was monitored for 28 days on the basis of two criteria: (1) serum levels of AST enzyme at 3-day intervals and (2) liver biopsies at weekly intervals and at the time of sacrifice at the end of the study period. In the untreated control group, an elevation of AST was found to peak at day 6 after grafting, and it remained elevated until day 28 (AST 542 +/- 72 U/l). Histologically, signs of severe rejection were first observed on day 9; these changed to moderate rejection about day 21 and to mild rejection by day 28, when the animals were sacrificed. Recipients pre-treated with anti-CD8 demonstrated a significant elevation of AST within 6 days that, unlike in the control recipients, continued to rise sharply through the observation period (AST 1127 +/- 181 U/l, P = 0.009 vs control group). Liver biopsies showed mild rejection at day 9 and moderate rejection at days 21 through 28. Recipients pretreated with anti-CD4 showed a time course of enzyme elevation and severity of rejection that was not significantly different from that observed in the control group. However, anti-CD4 treatment resulted in only 75% depletion of CD4+ cells in peripheral blood as compared to complete elimination of CD8+ cells following anti-CD8 treatment. Functional studies of spleen and liver-infiltrating lymphocytes obtained after 28 days showed low proliferative response in mixed lymphocyte culture with both BN and PVG stimulator spleen and lymph node cells. These results suggest that in this donor/recipient combination, removal of CD8+ cells increases the severity of rejection as demonstrated by a progressive rise in AST and histology. Moreover, OLT in this combination results in a profound, nonspecific inhibition of proliferative T-cell responses to MHC alloantigens.
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PMID:Liver allograft rejection in rats depleted of CD8+ cells. 887 94

We encountered six patients with pneumonitis related to blended chinese traditional medicine (Kampo). The duration of treatment with kampo ranged from 14 to 110 days (mean: 38 days). The most common complaints were dyspnea, fever, and dry coughing. Fine crackles were heard at the bases of both lungs. Abnormal laboratory findings included high values of C-reactive protein and glutamic-oxaloacetic transaminase in all patients, lactate dehydrogenase in 5 patients, and eosinophil count in 1 patient. Chest X-ray films and CT films revealed diffuse reticulo-nodular interstitial shadows with consolidation in both lung fields in 3 patients and pleural effusion in 1 patient. Bronchoalveolar lavage was done in 4 patients; examination of the lavage fluid showed lymphocyte alveolitis, either pure or associated with neutrophilia and eosinophilia in 3 patients. Inverted CD4/CD8 lymphocyte ratios were found in 3 patients. Transbronchial lung biopsy was done in 4 patients and specimens from 3 of those 4 showed organizing pneumonitis with thickening of alveolar septa. Lymphocyte stimulation tests were positive in 4 patients. Discontinuation of the drug (2 patients) or administration of corticosteroids (4 patients) was followed by rapid improvement. Patients being treated with kampo preparations should be observed for signs and symptoms of drug-induced pneumonitis.
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PMID:[Six patients with pneumonitis related to blended Chinese traditional medicines]. 902 15

In 14 patients with polymyositis (PM), 5 patients (2 males and 3 females) were positive for anti-hepatitis C virus (HCV) antibody measured by a second generation assay. We analysed the clinical characteristics and histopathological findings of the biopsied muscles from those 5 patients. They aged from 42 to 65 years averaging 53.6 years. Two asymptomatic patients visited our hospital due to elevated muscle enzyme levels, who had slight weakness in their orbicularis oculi and neck muscles on physical examination. The other 3 patients had moderate weakness of the proximal muscles. Anti-nuclear antibody was positive in 2 of the 5 patients and anti-Jo 1 antibody was negative in all patients. The serum enzymes elevated were creatine kinase (215-2, 207 (IU/l)) and glutamate oxaloacetate transaminase (40-119 (KU)). HCV-RNA was positive in the sera of 4 patients examined. All muscle biopsy specimens revealed variation in fiber size with inflammatory cellular infiltration and observed degenerating and regenerating fibers. The scant infiltration type was observed in 2 asymptomatic patients in whom the infiltrated cells were CD4 positive. The endomysial infiltration type was observed in 3 symptomatic patients; CD8 positive cells were found focally to diffusely in 2 patients examined. The expression of class 1 molecules from the major histocompatibility complex was detected mainly in infiltrated fibers to variable degrees. All of the patients showed a good response to the initial steroid therapy. The present study suggests that autoimmune reaction related to HCV infection causes myositis, therefore anti-HCV antibody should be checked in cases of PM.
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PMID:[Clinical characteristics and muscle histopathology in polymyositis positive anti-hepatitis with C virus antibody]. 921 18

Propagermanium is an organic germanium compound with immunopotentiating activity. We examined the hepatoprotective effect of propagermanium and its mechanism in an experimental animal model of acute liver injury induced with Corynebacterium parvum (C. parvum) and lipopolysaccharide (LPS) injection. Oral pretreatment with propagermanium decreased alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activity in a dose-dependent manner. Significant attenuation of ALT and AST activity was obtained at a dose of 3 mg/kg. Administration of propagermanium also inhibited the infiltration of mononuclear cells into the liver of mice induced by C. parvum/LPS. Immunohistochemical examination revealed infiltration of the liver by CD4-, CD8-, CD11b- and Gr-1-positive cells. Propagermanium prevented CD4- and CD11b-positive cells from infiltrating the liver. In this animal model, blood cytokine levels increased rapidly after LPS injection, causing severe hepatitis. Notably, tumour necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) are important mediators of the progress of liver injury. We demonstrated that propagermanium reduced IFN-gamma production by 53% at a dose of 3 mg/kg and also significantly inhibited the production of interleukin-12 (IL-12). These results indicate that propagermanium inhibits cell infiltration in the liver and cytokine production, and improves massive liver injury in C. parvum/LPS mice.
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PMID:Hepatoprotective effect of propagermanium on Corynebacterium parvum and lipopolysaccharide-induced liver injury in mice. 971 10

Little is understood of the anatomical fate of activated T lymphocytes and the consequences they have on the tissues into which they migrate. Previous work has suggested that damaged lymphocytes migrate to the liver. This study compares class I versus class II major histocompatibility complex (MHC)-restricted ovalbumin-specific T cell antigen receptor (TCR) transgenic mice to demonstrate that after in vivo activation with antigen the emergence of CD4(-)CD8(-)B220(+) T cells occurs more frequently from a CD8(+) precursor than from CD4(+) T cells. Furthermore, this change in phenotype is conferred only by the high affinity native peptide antigen and not by lower affinity peptide variants. After activation of CD8(+) cells with only the high affinity peptide, there is also a dramatically increased number of liver lymphocytes with accompanying extensive hepatocyte damage and elevation of serum aspartate transaminase. This was not observed in mice bearing a class II MHC-restricted TCR. The findings show that CD4(-)CD8(-)B220(+) T cells preferentially derive from a CD8(+) precursor after a high intensity TCR signal. After activation, T cells can migrate to the liver and induce hepatocyte damage, and thereby serve as a model of autoimmune hepatitis.
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PMID:Liver damage preferentially results from CD8(+) T cells triggered by high affinity peptide antigens. 974 33

The indolizidine alkaloid swainsonine, a potent inhibitor of Golgi alpha-mannosidase II, has been shown to reduce tumor cell metastasis, enhance cellular immune responses, and reduce solid tumor growth in mice. In our previous Phase I study, swainsonine administered by 5-day continuous infusion inhibited L-phytohemagglutinin-reactive N-linked oligosaccharide expression on peripheral blood lymphocytes. Significant toxicities included edema and elevated serum aspartate aminotransferase (AST). One patient with head and neck cancer had objective (>50%) tumor remission. Two patients showed symptomatic improvement. The objectives of this Phase IB trial were to examine the pharmacokinetics, toxicities, and biochemical effects of bi-weekly oral swainsonine at escalating dose levels (50-600 microgram/kg) in 16 patients with advanced malignancies and 2 HIV-positive patients unsuitable for conventional therapy. Eastern Cooperative Oncology Group performance status was </=2. The maximum tolerated dose was defined as 300 microgram/kg/day due primarily to serum AST abnormalities and dyspnea. Other adverse events present in >20% of patients included increase in serum AST (all patients), fatigue (n = 9), anorexia (n = 6), dyspnea (n = 6), and abdominal pain (n = 4). Inhibition of Golgi alpha-mannosidase II occurred in a dose-dependent manner. Examination of immunological parameters revealed a transient decrease in CD25(+) peripheral blood lymphocytes and, in seven of eight patients, an increase in CD4(+):CD8(+) ratios at 2 weeks. Serum drug levels peaked 3-4 h following a single oral dose in most patients and were proportional to dose at levels >/=150 microgram/kg. We conclude that oral swainsonine is tolerated by chronic intermittent administration at doses up to 150 microgram/kg/day. Adverse events considered drug related were similar to those observed in the infusional study but with fatigue and neurological effects also noted. Investigations of alternative dosing schedules with low starting doses are suggested for further clinical testing.
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PMID:Phase IB clinical trial of the oligosaccharide processing inhibitor swainsonine in patients with advanced malignancies. 981 86


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