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1.
Zhonghua Bing Li Xue Za Zhi ; 53(6): 598-604, 2024 Jun 08.
Article in Chinese | MEDLINE | ID: mdl-38825906

ABSTRACT

Objective: To investigate the clinicopathological, immunophenotypic and molecular genetic characteristics, and differential diagnosis of NTRK-rearranged spindle cell neoplasms (NTRK-RSCNs) in the gastrointestinal tract. Methods: Two NTRK-RSCNs diagnosed at the Department of Pathology of the First Affiliated Hospital of Zhengzhou University, Zhengzhou, China and one case diagnosed at Zhengzhou Central Hospital, Zhengzhou, China from 2019 to 2022 were collected. The clinical data, histopathology, immunophenotypes and prognosis were analyzed. Fluorescence in situ hybridization (FISH) and next-generation sequencing (NGS) were used to detect NTRK gene rearrangements, while relevant literature was also reviewed and discussed. Results: Two patients were male and one was female, with the age of 17, 47 and 62 years, respectively. The tumors were located in the duodenum, ascending colon and descending colon, respectively. The tumors were protuberant masses with gray and rubbery sections. Their maximum diameter was 2.5, 5.0 and 10.0 cm, respectively. Histologically, the tumors invaded mucosa, intrinsic muscle and serosal adipose tissue. Tumor cells consisted of spindle or oval shaped cells with monotonous morphology and arranged in bundles or stripes pattern. Spindle cells were mildly to moderately atypical, with slightly eosinophilic cytoplasm and inconspicuous nucleoli. Necrosis and mitotic figures were observed in one high-grade tumor. All tumors expressed CD34, S-100 and pan-TRK in varying degrees. FISH analysis showed that NTRK1 gene was break-apart in 1 case and NTRK2 gene break-apart in 2 cases. NGS technologies showed LMNA::NTRK1 fusion in one case, STRN::NTRK2 fusion in another case. All patients recovered well after the surgery without recurrence at the end of the follow-up. Conclusions: NTRK-RSCN is rarely diagnosed in the gastrointestinal tract and has significant variations in morphology. It overlaps with various other mesenchymal tumors which should be considered as differential diagnoses. Be familiar with the features of histological morphology in combination with immunophenotype and molecular genetic characteristics can not only help diagnose NTRK-RSCNs, but provide therapeutic targets for clinical treatment.


Subject(s)
Gastrointestinal Neoplasms , In Situ Hybridization, Fluorescence , Receptor, trkA , Humans , Male , Female , Middle Aged , Receptor, trkA/genetics , Receptor, trkA/metabolism , Gastrointestinal Neoplasms/genetics , Gastrointestinal Neoplasms/pathology , Adolescent , Gene Rearrangement , Diagnosis, Differential , High-Throughput Nucleotide Sequencing , Receptor, trkB/genetics , Receptor, trkB/metabolism
2.
Zhonghua Wai Ke Za Zhi ; 60(11): 987-991, 2022 Nov 01.
Article in Chinese | MEDLINE | ID: mdl-36323580

ABSTRACT

In recent years, great progress has been made in the treatment of Stanford type B aortic dissection, especially endovascular repair technology has become the main treatment. However, it is only used to repair the primary tear, the residual tears and false lumen are often left at the distal end, which causes adverse events such as distal aortic dilatation or even rupture. At present, there are many studies on the influencing factors of aortic remodeling, which provide some references for the prognosis of patients.The aorta carries the transportation of blood flow, and various factors affecting hemodynamics also affect the remodeling of aorta. Some researchers reported several factors related to negative remodeling and added auxiliary techniques, and achieved gratifying results. However, because of the different conditions of each patient, the specific treatment method is still unclear, the factors affecting the aortic remodeling effect also have not been thoroughly studied. Clarifying the influencing factors of negative remodeling is helpful to screen high-risk patients, optimize the treatment plan and improve the prognosis.


Subject(s)
Aortic Aneurysm, Thoracic , Blood Vessel Prosthesis Implantation , Endovascular Procedures , Humans , Aortic Aneurysm, Thoracic/surgery , Blood Vessel Prosthesis Implantation/adverse effects , Endovascular Procedures/methods , Treatment Outcome , Aorta , Risk Factors , Retrospective Studies
3.
Eur Rev Med Pharmacol Sci ; 23(12): 5422-5431, 2019 Jun.
Article in English | MEDLINE | ID: mdl-31298395

ABSTRACT

OBJECTIVE: Atrial fibrillation (AF) is independently associated with a higher risk of acute myocardial infarction (AMI). The occurrence of AMI in AF patients may lead to dismal prognosis. Risk assessment is a fundamental component of prevention for AMI. PATIENTS AND METHODS: 2419 consecutive patients with nonvalvular AF were enrolled in this retrospective study. A logistic regression analysis was performed on clinical variables to create a simple clinical prediction rule. The following nine variables and assigned scores (in brackets) were included in the prediction rule: age ≥65 years (1.0), heart failure (1.0), hypertension (1.0), diabetes mellitus (1.0), hyperlipidemia (0.5), history of stroke/TIA (0.5), vascular disease (1.0), current smoking (0.5), and resting heart rate >90 beats/min (1.0). Patients were considered to have a low probability if the score was ≤2.5, moderate if the score was 3.0 to 4.0, and high if the score was ≥4.5. The AMI unlikely was assigned to patients with scores <3.5 and AMI likely if the score was ≥3.5. To evaluate the score, we included an external validation cohort of 1810 nonvalvular AF patients from the Cardiology Center, Shandong Provincial Hospital affiliated to Shandong University, Jinan, China. RESULTS: The score showed a good ability in discriminating AF patients experiencing AMI both in the internal derivation cohort, with a c-index of 0.80 [95% Confidence Interval (CI) 0.77-0.83, p<0.001] and in the external validation cohort (c-index 0.73, 95% CI 0.69-0.77, p<0.001). Our scoring system offered significantly better predictive performance than the CHA2DS2-VASc score (c-index 0.80 vs 0.71, p<0.001). CONCLUSIONS: Our scoring system is a simple and accurate way of predicting the risk of AMI in AF patients. Therefore, more accurate targeting of preventive therapy will be allowed.


Subject(s)
Atrial Fibrillation/complications , Models, Statistical , Myocardial Infarction/epidemiology , Age Factors , Aged , Aged, 80 and over , China/epidemiology , Comorbidity , Diabetes Mellitus/epidemiology , Female , Heart Failure/epidemiology , Humans , Hyperlipidemias/epidemiology , Hypertension/epidemiology , Male , Middle Aged , Myocardial Infarction/etiology , Probability , Retrospective Studies , Risk Assessment/methods , Risk Factors , Smoking/epidemiology , Stroke/epidemiology
5.
Zhonghua Bing Li Xue Za Zhi ; 47(12): 941-944, 2018 Dec 08.
Article in Chinese | MEDLINE | ID: mdl-30522176

ABSTRACT

Objective: To investigate the clinicopathological features of gangliocytic paraganglioma(GP). Methods: Clinical data and pathological diagnosis of the 4 cases of GP were obtained through the medical record inquiry from January 2011 to December 2017 at the First Affiliated Hospital of Zhengzhou University. Routine HE staining and immunohistochemistry of CKpan, Syn, CgA, CD56, NSE and NF were performed. Clinical follow-up of the patients was obtained through telephone communication. Results: All 4 patients, including 2 male and 2 female patients, presented with intermittent abdominal pain and distention. The median age was 56 years. Preoperative CT showed local thickening of the duodenum wall with slight enhancement in all four cases. Endoscopic ultrasonography showed low level echo in the mucous layer and submucosa involved by the tumor in 3 of 4 cases. The maximal diameter of the tumor ranged from 0.6 to 1.8 cm with an average of 1.2 cm. Microscopically, the tumors consisted of epithelioid, spindle and ganglion-like cells, and the proportion of the three cell types was different among cases. Epithelioid cells expressed CKpan, Syn, CgA and CD56. Spindle cells expressed S-100 protein and SOX-10 and ganglion-like cells expressed NF, Syn, CgA and CD56.All tumour cells expressed NSE. All 4 patients had no recurrence a post-surgery follow-up period of 3 to 30 months. Conclusions: GP of the duodenum is a benign tumor with excellent prognosis after endoscopic excision. Although its incidence is very low, its diagnosis should be considered for any mass lesion of the duodenum, especially involving mucosa and submucosa of the second dudenal segment.


Subject(s)
Duodenal Neoplasms/chemistry , Duodenal Neoplasms/pathology , Paraganglioma/chemistry , Paraganglioma/pathology , CD56 Antigen/analysis , Carrier Proteins/analysis , Creatine Kinase/analysis , Duodenal Neoplasms/diagnostic imaging , Female , Glycoprotein Hormones, alpha Subunit/analysis , Humans , Immunohistochemistry , Male , Middle Aged , Oligodeoxyribonucleotides , Paraganglioma/diagnostic imaging , Prognosis , S100 Proteins , Synapsins/analysis
8.
9.
Zhonghua Gan Zang Bing Za Zhi ; 24(9): 676-680, 2016 Sep 20.
Article in Chinese | MEDLINE | ID: mdl-27788724

ABSTRACT

Objective: To investigate the value of spectral CT-based quantitative analysis in the differential diagnosis of liver cancer and liver abscess. Methods: A total of 70 patients with space-occupying lesions in the liver(45 with liver cancer and 25 with liver abscess)underwent spectral CT scans to obtain spectral images in the arterial phase and portal venous phase. The solid constituents of lesions and the iodine and water concentrations in necrotic or cystic parts of lesions, normal hepatic tissue, and abdominal aorta in the arterial phase and portal venous phase were measured, and the normalized iodine concentration(NIC)and lesion-to-normal hepatic tissue ratio(LNR)of iodine concentration were calculated. The two samples t-test and the receiver operating characteristic(ROC)curve analysis were performed for the quantitative indices above. Results: The patients with liver cancer had higher NIC and LNR in solid constituents in the arterial phase than those with liver abscess(NIC: 0.15±0.06 mg/ml vs 0.14±0.02 mg/ml, P > 0.05; LNR: 2.78±0.65 vs 1.45±0.88, P < 0.001). The patients with liver abscess had significantly higher NIC and LNR in solid constituents in the portal venous phase than those with liver cancer(NIC: 0.65±0.08 mg/ml vs 0.52±0.08 mg/ml, P≤0.001; LNR: 1.22±0.23 vs 0.95±0.15, P≤0.001). There were no significant differences in NIC in the arterial phase or NIC and LNR in the portal venous phase in necrotic or cystic parts of lesions between the patients with liver cancer and liver abscess(P > 0.05). The optimal quantitative value for the differential diagnosis of liver cancer and liver abscess was LNR in arterial phase, and the cut-off value of 1.53 had a sensitivity of 100% and a specificity of 92%. Conclusion: Quantitative iodine concentration analysis in spectral CT imaging has a certain value in the differential diagnosis of liver cancer and liver abscess and can improve the accuracy of diagnosis.


Subject(s)
Carcinoma, Hepatocellular/diagnostic imaging , Liver Abscess/diagnostic imaging , Liver Neoplasms/diagnostic imaging , Tomography, X-Ray Computed/methods , Adult , Arteries , Carcinoma, Hepatocellular/pathology , Contrast Media , Diagnosis, Differential , Female , Humans , Iodine , Liver Neoplasms/pathology , Male , Middle Aged , Necrosis/diagnostic imaging , Portal Vein/diagnostic imaging , ROC Curve , Radiographic Image Enhancement/methods , Reproducibility of Results , Sensitivity and Specificity , Tomography, Spiral Computed/methods
10.
Genet Mol Res ; 14(4): 16491-6, 2015 Dec 09.
Article in English | MEDLINE | ID: mdl-26662448

ABSTRACT

The aim of this study was to characterize variations in Raf kinase inhibitor protein (RKIP) expression and related signaling molecules in gastric cardia adenocarcinoma. Cancerous and precancerous tissues were collected from patients with gastric cardia adenocarcinoma and normal tissue was collected from healthy controls. RKIP expression was detected in these tissues and the serum levels of NF-κB p65 and T-lymphocyte subsets were measured. Positive RKIP expression was higher in gastric cardia adenocarcinoma tissues than in precancerous tissues. The serum level of total NF-κB p65 was higher in patients with gastric cardia adenocarcinoma than in healthy controls. Levels of NF-κB p65 did not correlate with positive and negative expression of RKIP, but were higher in patients with lymph node metastasis than in those without it. The cellular immune function of the gastric cardia adenocarcinoma group was lower than in normal controls, particularly in cases with negative RKIP expression. RKIP is downregulated in gastric cardia adenocarcinoma tissues, which is related to the occurrence, progression, invasion, and metastasis of tumors. The possible mechanism for this may be the inhibition of NF-κB activity and cellular immune function, which allows for the escape of tumor cells from immune surveillance.


Subject(s)
Adenocarcinoma/immunology , Adenocarcinoma/metabolism , Phosphatidylethanolamine Binding Protein/metabolism , Stomach Neoplasms/immunology , Stomach Neoplasms/metabolism , T-Lymphocyte Subsets/immunology , Transcription Factor RelA/metabolism , Adenocarcinoma/blood , Adenocarcinoma/pathology , Adult , Aged , Aged, 80 and over , Biomarkers , Disease Progression , Female , Gene Expression , Humans , Immunohistochemistry , Immunophenotyping , Lymphatic Metastasis , Lymphocyte Count , Male , Middle Aged , Neoplasm Staging , Phenotype , Phosphatidylethanolamine Binding Protein/genetics , Stomach Neoplasms/blood , Stomach Neoplasms/pathology , T-Lymphocyte Subsets/metabolism , Transcription Factor RelA/blood
11.
Genet Mol Res ; 14(3): 8366-74, 2015 Jul 28.
Article in English | MEDLINE | ID: mdl-26345763

ABSTRACT

Physical localization of molecular markers and assignment of the 15th linkage group to chromosome 11 of the karyotype in cassava (Manihot esculenta Crantz) were achieved using primed in situ labeling. Amplified signals for both the EST507-1 and SSRY13-5 markers were consistently observed in different stages of cell division. A comparison of the length, arm ratio, and other morphological characteristics of somatic metaphase chromosomes in karyotype analysis indicated that the EST507-1 and SSRY13-5 markers were localized on the short and long arm of cassava chromosome 11 with the relative map positions of 41.67 and 23.07, respectively. The physical localization of the 2 markers on chromosome 11 of the karyotype corresponds to their positions on the 15th linkage group in cassava.


Subject(s)
Genetic Linkage , Genetic Markers , Manihot/genetics , Cell Division/genetics , Chromosome Mapping , Genotype , Karyotyping , Manihot/cytology
12.
Eur Rev Med Pharmacol Sci ; 16(3): 299-304, 2012 Mar.
Article in English | MEDLINE | ID: mdl-22530344

ABSTRACT

OBJECTIVES: In this study, we investigated the effect of grape seed proanthocyanidins extracts (GSPE), which have been proved to have anti-oxidative and anti-aging functions, on the expression of apoA-L at mRNA level of HepG2 cells in vitro under the experimental conditions of high-sugar and sugar. MATERIALS AND METHODS: Cell viability was measured by sulforhodamine B (SRB). The apoA-I mRNA expression was assayed by real-time fluorescence quantitative polymerase chain reaction. Firstly, HepG2 cells were incubated in 10% inactivated newborn calf serum in Dulbecco's Modified Eagle Medium (DMEM). Next, cells were incubated with high-sugar and sugar serum-free medium, and added different concentration of GSPE (2.5, 5 and 10 microg/ml) for more than 24 hours, and thereafter, investigated whether GSPE can promote more apoA-I expression in HepG2 cells under the experimental conditions of high-sugar and sugar. RESULTS: In this experiment, HepG2 cells were incubated with high-sugar and sugar serum-free medium, and HepG2 cells incubated with high-sugar medium produced less apoA-I at mRNA level. The difference was significant (p < 0.05). When HepG2 cells were incubated with GSPE at concentration of 20 microg/ml or above for about 4 hours, cell viability measured by SRB was lower than 50%. However, cell viability of HepG2 cells incubated with GSPE at concentration of 10 microg/ml or below was higher than 70%. Therefore, we chose the HepG2 cells incubated with GSPE concentration of 2.5, 5, 10 microg/ml to observe the effect of GSPE on the mRNA expression of apoA-I. After incubated with GSPE, the apoA-I expression of HepG2 cells were significantly elevated at mRNA level compared to that of high sugar control (p < 0.05). Moreover, this action of GSPE showed dose dependent, and the dose of 2.5 microg/ml was optimal. CONCLUSIONS: GSPE (concentration of higher than 20 microg/ml) could inhibit HepG2 cell survival, and in HepG2 cells, endogenous apoA-I was significantly suppressed following 24h of exposure to high concentrations of glucose. Meanwhile GSPE could promote expression of apoA-L dose dependently at mRNA level when its concentration was lower than 10 microg/ml.


Subject(s)
Apolipoprotein A-I/biosynthesis , Carbohydrates/pharmacology , Proanthocyanidins/pharmacology , Vitis/chemistry , Actins/biosynthesis , Actins/genetics , Apolipoprotein A-I/genetics , Cell Line, Tumor , Cell Survival/drug effects , Electrophoresis, Agar Gel , Gene Expression/drug effects , Hep G2 Cells , Humans , Plant Extracts/pharmacology , Proanthocyanidins/chemistry , RNA, Messenger/biosynthesis , RNA, Messenger/genetics , Real-Time Polymerase Chain Reaction , Seeds/chemistry
13.
Genet Mol Res ; 9(3): 1896-907, 2010 Sep 21.
Article in English | MEDLINE | ID: mdl-20882485

ABSTRACT

We examined the effect of polymorphisms in the endothelial nitric oxide synthase gene on the risk for essential hypertension in a Han Chinese population through a meta-analysis of data from 15 studies. Associations between increased risk for essential hypertension and 4b/a were obtained in a dominant model and allele contrast (aa + ab vs bb: odds ratio (OR)(FE) = 1.26, 95% confidence interval (CI) = 1.10-1.44; a vs b allele: OR(FE) = 1.23, 95%CI: 1.09-1.40). Four studies with sample sizes over 500 produced similar results. No evidence of publication bias was found. Also, no significant heterogeneity was observed among these studies. When we examined the G894T polymorphism, we found a marginally significant association for allele contrast and the recessive model when all the eligible studies were pooled together. However, there was no evidence for a significant association after the exclusion of two studies deviating from Hardy-Weinberg equilibrium in the control group. Heterogeneity among studies was observed. Results of cumulative and recursive cumulative meta-analysis indicated that more studies are needed to objectively determine the effects of these two polymorphisms.


Subject(s)
Hypertension/genetics , Nitric Oxide Synthase Type III/genetics , Polymorphism, Genetic/genetics , Adult , Aged , Asian People/genetics , Female , Genetic Predisposition to Disease , Humans , Male , Middle Aged
14.
J Int Med Res ; 37(5): 1443-9, 2009.
Article in English | MEDLINE | ID: mdl-19930849

ABSTRACT

This study investigated the value of arterial elasticity measurement in the early diagnosis of angiographic coronary artery atherosclerosis in 105 consecutive elderly patients. They were divided into two groups according to the results of selective coronary angiography: 55 with coronary atherosclerosis and 50 with a normal coronary angiogram. The Gensini score of the coronary artery was acquired and capacitive arterial compliance (C1) and oscillatory arterial compliance (C2) were measured. An independent-sample t-test was used to evaluate the difference in C1 and C2 between the two groups. Bivariate analyses were performed to study the association between the Gensini score and C1 and C2. A significant difference between the two groups in C2 was found and the Gensini score of the coronary artery was significantly correlated with C2. Identification of early coronary atherosclerosis in geriatrics may be aided by the prognostic value of C2.


Subject(s)
Coronary Angiography , Coronary Artery Disease/diagnostic imaging , Coronary Vessels/pathology , Vascular Resistance/physiology , Aged , Coronary Artery Disease/blood , Elasticity , Female , Humans , Male , Retrospective Studies , Risk Factors
15.
J Virol ; 75(23): 11874-80, 2001 Dec.
Article in English | MEDLINE | ID: mdl-11689669

ABSTRACT

The synthesis of retroviral DNA is initiated near the 5' end of the RNA. DNA synthesis is transferred from the 5' end to the 3' end of viral RNA in an RNase H-dependent step. In the case of human immunodeficiency virus type 1 (HIV-1) (and certain other retroviruses that have complex secondary structures at the ends of the viral RNA), there is the possibility that DNA synthesis can lead to a self-priming event that would block viral replication. The extent of RNase H cleavage must be sufficient to allow the strand transfer reaction to occur, but not so extensive that self-priming occurs. We have used a series of model RNA substrates, with and without a 5' cap, to investigate the rules governing RNase H cleavage at the 5' end of the HIV-1 genome. These in vitro RNase H cleavage reactions produce an RNA fragment of the size needed to block self-priming but still allow strand transfer. The cleavages seen in vitro can be understood in light of the structure of HIV-1 reverse transcriptase in a complex with an RNA/DNA substrate.


Subject(s)
Genome, Viral , HIV-1/genetics , Ribonuclease H/metabolism , Base Sequence , DNA, Viral/genetics , Hydrolysis , Promoter Regions, Genetic , RNA, Viral/genetics
16.
J Atheroscler Thromb ; 8(1): 30-2, 2001.
Article in English | MEDLINE | ID: mdl-11686313

ABSTRACT

Increasing evidence has indicated the important roles of inflammation and immune response in the development of atherosclerosis and ischemic heart disease (IHD). We measured the serum interleukin (IL)-8 and IL-12 levels of patients with unstable angina pectoris (UAP) and patients with acute myocardial infarction (AMI), and compared findings with those of normal subjects. The results showed that the serum level of IL-8 was significantly higher in patients with UAP and patients with AMI than in healthy control subjects. To our knowledge, this is the first report that serum IL-12 level was elevated in patients with AMI but not in patients with UAP. These findings suggest that IL-8 and IL-12 are involved in the process of IHD, and serum IL-12 may be a marker for differentiating AMI from UAP.


Subject(s)
Interleukin-12/blood , Interleukin-8/blood , Myocardial Ischemia/blood , Aged , Angina Pectoris/blood , China , Female , Humans , Male , Middle Aged , Reference Values
17.
J Virol ; 75(14): 6321-8, 2001 Jul.
Article in English | MEDLINE | ID: mdl-11413298

ABSTRACT

When human immunodeficiency virus type 1 (HIV-1) is selected for resistance to 3TC, the methionine normally present at position 184 is replaced by valine or isoleucine. Position 184 is the X of the conserved YXDD motif; positions 185 and 186 form part of the triad of aspartic acids at the polymerase active site. Structural and biochemical analysis of 3TC-resistant HIV-1 reverse transcriptase (RT) led to a model in which a beta-branched amino acid at position 184 would act as a steric gate. Normal deoxynucleoside triphosphates (dNTPs) could still be incorporated; the oxathiolane ring of 3TCTP would clash with the beta branch of the amino acid at position 184. This model can also explain 3TC resistance in feline immunodeficiency virus and human hepatitis B virus. However, it has been reported (14) that murine leukemia viruses (MLVs) with valine (the amino acid present in the wild type), isoleucine, alanine, serine, or methionine at the X position of the YXDD motif are all resistant to 3TC. We prepared purified wild-type MLV RT and mutant MLV RTs with methionine, isoleucine, and alanine at the X position. The behavior of these RTs was compared to those of wild-type HIV-1 RT and of HIV-1 RT with alanine at the X position. If alanine is present at the X position, both MLV RT and HIV-1 RT are relatively resistant to 3TCTP in vitro. However, the mutant enzymes were impaired relative to their wild-type counterparts; there appears to be steric hindrance for both 3TCTP and normal dNTPs.


Subject(s)
Anti-HIV Agents/pharmacology , Cytidine Triphosphate/pharmacology , HIV-1/drug effects , Lamivudine/pharmacology , Moloney murine leukemia virus/drug effects , RNA-Directed DNA Polymerase/genetics , Alanine , Animals , Cytidine Triphosphate/analogs & derivatives , Dideoxynucleotides , Drug Resistance, Microbial , HIV Reverse Transcriptase/chemistry , HIV Reverse Transcriptase/genetics , HIV-1/enzymology , HIV-1/genetics , Humans , Isoleucine , Lamivudine/analogs & derivatives , Methionine , Molecular Conformation , Moloney murine leukemia virus/enzymology , Moloney murine leukemia virus/genetics , Point Mutation , RNA-Directed DNA Polymerase/chemistry , Virus Replication/drug effects
18.
Virology ; 282(1): 206-13, 2001 Mar 30.
Article in English | MEDLINE | ID: mdl-11259203

ABSTRACT

Escherichia coli RNase H has a basic extension that is involved in binding nucleic acid substrates. This basic extension is present in the RNase H of Moloney murine leukemia virus reverse transcriptase (MLV RT), but has been deleted from the RNase H of HIV-1 RT. Previous work showed that removing the basic loop from MLV RT (the mutant is called DeltaC) blocked viral replication; however, DeltaC MLV RT retained RNase H activity in an in situ gel assay. We prepared recombinant DeltaC MLV RT and compared its activity to wild-type MLV RT. The DeltaC mutant is impaired in both polymerase and RNase H activity; the pattern of defects suggests that the basic loop is involved in the binding of MLV RT to a heteropolymeric template-primer.


Subject(s)
Catalytic Domain , DNA-Directed DNA Polymerase/genetics , Moloney murine leukemia virus/enzymology , RNA-Directed DNA Polymerase/genetics , Ribonuclease H/genetics , Animals , DNA-Directed DNA Polymerase/metabolism , Mice , Mutation , RNA-Directed DNA Polymerase/metabolism , Recombinant Proteins/metabolism , Ribonuclease H/metabolism
19.
J Mol Biol ; 300(2): 403-18, 2000 Jul 07.
Article in English | MEDLINE | ID: mdl-10873473

ABSTRACT

Treating HIV infections with drugs that block viral replication selects for drug-resistant strains of the virus. Particular inhibitors select characteristic resistance mutations. In the case of the nucleoside analogs 3TC and FTC, resistant viruses are selected with mutations at amino acid residue 184 of reverse transcriptase (RT). The initial change is usually to M184I; this virus is rapidly replaced by a variant carrying the mutation M184V. 3TC and FTC are taken up by cells and converted into 3TCTP and FTCTP. The triphosphate forms of these nucleoside analogs are incorporated into DNA by HIV-1 RT and act as chain terminators. Both of the mutations, M184I and M184V, provide very high levels of resistance in vivo; purified HIV-1 RT carrying M184V and M184I also shows resistance to 3TCTP and FTCTP in in vitro polymerase assays. Amino acid M184 is part of the dNTP binding site of HIV-1 RT. Structural studies suggest that the mechanism of resistance of HIV-1 RTs carrying the M184V or M184I mutation involves steric hindrance, which could either completely block the binding of 3TCTP and FTCTP or allow binding of these nucleoside triphosphate molecules but only in a configuration that would prevent incorporation. The available kinetic data are ambiguous: one group has reported that the primary effect of the mutations is at the level of 3TCTP binding; another, at the level of incorporation. We have approached this problem using assays that monitor the ability of HIV-1 RT to undergo a conformational change upon binding a dNTP. These studies show that both wild-type RT and the drug-resistant variants can bind 3TCTP at the polymerase active site; however, the binding to M184V and M184I is somewhat weaker and is sensitive to salt. We propose that the drug-resistant variants bind 3TCTP in a strained configuration that is salt-sensitive and is not catalytically competent.


Subject(s)
HIV Reverse Transcriptase/antagonists & inhibitors , HIV Reverse Transcriptase/chemistry , HIV-1/enzymology , Lamivudine/metabolism , Lamivudine/pharmacology , Amino Acid Substitution/genetics , Anti-HIV Agents/metabolism , Anti-HIV Agents/pharmacology , Binding Sites , Catalysis , Deoxycytosine Nucleotides/metabolism , Deoxycytosine Nucleotides/pharmacology , Deoxyribonucleotides/metabolism , Drug Resistance, Microbial/genetics , HIV Reverse Transcriptase/genetics , HIV Reverse Transcriptase/metabolism , Models, Molecular , Mutation/genetics , Nuclease Protection Assays , Oligodeoxyribonucleotides/genetics , Oligodeoxyribonucleotides/metabolism , Protein Binding/drug effects , Protein Conformation , RNA/biosynthesis , RNA/chemistry , RNA/genetics , RNA/metabolism , RNA-Binding Proteins/antagonists & inhibitors , RNA-Binding Proteins/chemistry , RNA-Binding Proteins/genetics , RNA-Binding Proteins/metabolism , Reverse Transcriptase Inhibitors/metabolism , Reverse Transcriptase Inhibitors/pharmacology , Ribonuclease H/metabolism , Salts/pharmacology , Static Electricity , Templates, Genetic , Transcription, Genetic
20.
J Mol Biol ; 294(5): 1097-113, 1999 Dec 17.
Article in English | MEDLINE | ID: mdl-10600369

ABSTRACT

Retroviral revXerse transcriptases (RTs) have an associated RNase H activity that can cleave RNA-DNA duplexes with considerable precision. We believe that the structure of the RNA-DNA duplexes in the context of RT determines the specificity of RNase H cleavage. To test this idea, we treated three related groups of synthetic RNA-DNA hybrids with either Moloney murine leukemia virus (MLV) RT or human immunodeficiency virus type 1 (HIV-1) RT. All of the hybrids were prepared using the same 81-base RNA template. The first series of RNase H substrates was prepared with complementary DNA oligonucleotides of different lengths, ranging from 6 to 20 nucleotides, all of which shared a common 5' end and were successively shorter at their 3' ends. The second series of oligonucleotides had a common 3' end but shorter 5' ends. The DNA oligonucleotides in the third series were all 20 bases long but had non-complementary stretches at either the 5' end, 3' end, or both ends. Several themes have emerged from the experiments with these RNA-DNA duplexes. (1) Both HIV-1 RT and MLV RT cleave fairly efficiently if the duplex region is at least eight bases long, but not if it is shorter. (2) Although, under the conditions we have used, both enzymes require the substrate to have a region of RNA-DNA duplex, both MLV RT and HIV-1 RT can cleave RNA outside the region that is part of the RNA-DNA duplex. (3) The polymerase domain of HIV-1 RT uses certain mismatched segments of RNA-DNA to position the enzyme for RNase H cleavage, whereas the polymerase domain of MLV RT does not use the same mismatched segments to define the position for RNase H cleavage. (4) For HIV-1 RT, a mismatched region near the RNase H domain can interfere with RNase H cleavage; cleavage is usually (but not always) more efficient if the mismatched segment is deleted. These results are discussed in regard to the structure of HIV-1 RT and the differences between HIV-1 RT and MLV RT.


Subject(s)
HIV Reverse Transcriptase/metabolism , Moloney murine leukemia virus/enzymology , RNA-Directed DNA Polymerase/metabolism , Ribonuclease H/metabolism , Amino Acid Sequence , Base Pair Mismatch/genetics , Base Sequence , Models, Molecular , Molecular Sequence Data , Molecular Weight , Nucleic Acid Conformation , Nucleic Acid Heteroduplexes/chemistry , Nucleic Acid Heteroduplexes/genetics , Nucleic Acid Heteroduplexes/metabolism , Oligodeoxyribonucleotides/chemistry , Oligodeoxyribonucleotides/genetics , Oligodeoxyribonucleotides/metabolism , RNA/chemistry , RNA/genetics , RNA/metabolism , Sequence Alignment , Structure-Activity Relationship , Substrate Specificity , Temperature , Templates, Genetic
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