Biomedical subjects

M Wang

Publications and source records attributed to M Wang.

At least 505 records · Page 28Linked to original sources

PubMed1998

Impairment of long-term potentiation and paired-pulse facilitation in rat hippocampal dentate gyrus following developmental lead exposure in vivo.

Neonatal rats were exposed to lead from parturition to weaning via the milk of dams drinking 0.2% lead acetate solution. The alterations of long-term potentiation (LTP) and paired-pulse facilitation (PPF) of hippocampal dentate gyrus in adult rats (90-115 days) following developmental lead exposure were studied in vivo. Input/output (I/O) function, paired-pulse facilitation (PPF), excitatory postsynaptic potential (EPSP) and population spike (PS) amplitude were measured in the dentate gyrus (DG) in response to stimulation applied to the lateral perforant path. The results showed that LTP was induced in control rats with an average PS potentiation of 321.1+/-50.0% (n=18), which was significantly greater than the increase in PS potentiation (173.5+/-30.0%, n=17, p<0.001) in lead-exposed rats after tetanizing stimulation. The mean EPSP potentiation increased to 172.4+/-27.0% (n=18) in control and 138.8+/-21.4% (n=17) in lead-exposed rats after tetanizing stimulation. The lead-induced impairment of LTP of PS potentiation was more serious than that of EPSP potentiation. Following pairs stimulation of perforant fiber at 250 microA and an interpulse interval (IPI) of 10-1000 ms, the average peak facilitation of PS was 211.3+/-25.0% (n=13) in control and 187.7+/-23.0% (n=11) in lead-exposed rats. The average facilitation period duration of PS was 243.0+/-35.8 ms (n=13) in control and 138.0+/-24.4 ms (n=11) in lead-exposed rats. These results suggested that developmental lead exposure in neonatal rats caused impairments in LTP and PPF of hippocampal dentate gyrus.

Animals↗

PubMed1998

Inhibition of lung carcinogenesis by black tea in Fischer rats treated with a tobacco-specific carcinogen: caffeine as an important constituent.

Here, we examined the effect of black tea and caffeine on lung tumorigenesis in F344 rats induced by the nicotine-derived carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) in a 2-year bioassay. NNK was administered s.c. at a dose of 1.5 mg/kg body weight three times weekly for 20 weeks. Animals were given either black tea as drinking water at concentrations of 2%, 1%, or 0.5%, or caffeine in drinking water at concentrations identical to those in 2% and 0.5% tea infusions for 22 weeks. The treatment period began 1 week before and ended 1 week after the NNK administration. The animals were sacrificed on week 101 for the examination of tumors in target organs, including lung, liver, nasal cavity, and other major organs. The NNK-treated group, given 2% black tea, showed a significant reduction of the total lung tumor (adenomas, adenocarcinomas, and adenosquamous carcinomas) incidence from 47% to 19%, whereas the group given 1% and 0.5% black tea showed no change. The 2% tea also reduced liver tumor incidence induced by NNK from 34% in the group given only deionized water to 12%. The tumor incidence in the nasal cavity, however, was not affected by either black tea or caffeine at any of the concentrations tested. The most unexpected finding was the remarkable reduction of the lung tumor incidence, from 47% to 10%, in the group treated with 680 ppm caffeine, a concentration equivalent to that found in the 2% tea. This incidence is comparable to background levels seen in the control group. This study demonstrated for the first time in a 2-year lifetime bioassay that black tea protects against lung tumorigenesis in F344 rats, and this effect appears to be attributed, to a significant extent, to caffeine as an active ingredient of tea.

Animals↗

PubMed1998

Point mutations (Thr240Arg and Gln311Stop) [correction of Thr240Arg and Ala311Stop] in the Parkin gene.

Autosomal recessive juvenile parkinsonism (AR-JP) is a distinct clinical and genetic entity characterized by selective degeneration of nigral neurons. Recently, the parkin gene responsible for AR-JP has been identified. To date, we found two different deletional mutations including single and multiple exonic deletions. In the present study, we identified two types of point mutations (Thr240Arg and Gln311Stop) involving exons 6 and 8 in the parkin gene of the AR-JP patients from two Turkish families. This is the first report on point mutations for the parkin gene. Furthermore, the Thr240Arg mutation was located on a consensus sequence for the site of phosphorylation by casein kinase II. Identification of its mutation provides an important clue as to the role of the Parkin protein in degeneration of the substantia nigra in the brain of AR-JP patients.

Adolescent↗

PubMed1998

Antigen-specific cytolysis by neutrophils and NK cells expressing chimeric immune receptors bearing zeta or gamma signaling domains.

TCR- and IgG-binding Fc receptors (Fc gamma R) mediate a variety of critical biologic activities including cytolysis via the structurally related zeta- and gamma-chains. In previous studies, we have described chimeric immune receptors (CIR) in which the ligand-binding domain of a heterologous receptor or Ab is fused directly to the cytoplasmic domain of the TCR zeta-chain. Such zeta-CIRs efficiently trigger cytotoxic function of both T and NK cells in a target-specific manner. In this report, we compared the ability of both zeta- and gamma-CIRs to activate the cytolytic function of two distinct classes of Fc gamma R-bearing effectors, NK cells and neutrophils. Mature neutrophils expressing zeta- and gamma-CIR were generated in vivo from murine hemopoietic stem cells following transplantation of syngeneic mice with retrovirally transduced bone marrow or in vitro from transduced human CD34+ progenitors following differentiation. Both zeta- and gamma-based CIRs were capable of activating target-specific cytolysis by both NK cells and neutrophils, although the zeta-CIR was consistently more efficient. The experimental approach described is a powerful one with which to study the role of nonlymphoid effector cells in the host immune system and permits the rational design of immunotherapeutic strategies that rely on harnessing multiple immune cell functions via CIR-modified hemopoietic stem cells or progenitors.

Adult↗

PubMed1998

[Interference of human processed pseudogene and corresponding counter-measures in reverse transcriptase-polymerase chain reaction].

OBJECTIVE: This study aimed to set up an effective method to find the interference of processed pseudogene and overcome it in RT-PCR. METHODS: Using RT-PCR methods, the authors amplified the cytokeratin 19 cDNA or DNA sequence in human lung squamous cell carcinoma samples. RESULTS: They could find the influence of pseudogene through performing genomic DNA and nonreversed transcribed RNA controls. By digesting the extracted RNA sample with RNase-free DNase or regulating the annealing temperature based on mismatched primers, they could effectively eliminate the interference. CONCLUSION: The presence of processed pseudogene usually interferes in the experimental protocol in RT-PCR. This problem can be resolved with the method aforementioned.

Carcinoma, Squamous Cell↗

PubMed1998

Identification of adenylyl cyclase isoenzymes in CHO and B82 cells.

The identification of adenylyl cyclase isoenzymes in mammalian host cells is important for the interpretation of data obtained from cell lines heterologously expressing G-protein coupled receptors. Reverse transcriptase polymerase chain reaction (RT-PCR) was used to amplify adenylyl cyclase cDNAs from Chinese hamster ovary (CHO) and mouse fibroblast (B82) cells. The isolated fragments were identified by restriction analyses and by sequencing. We found mRNAs for adenylyl cyclases VI and VII in CHO and adenylyl cyclases IX and VII in B82 cells.

Adenylyl Cyclases↗

PubMed1998

The CCR5 receptor acts as an alloantigen in CCR5Delta32 homozygous individuals: identification of chemokineand HIV-1-blocking human antibodies.

The chemokine receptor CCR5 is the major coreceptor for infection by macrophage-tropic R5 HIV-1. A 32-bp deletion in the gene coding for CCR5 (CCR5Delta32) occurs with a frequency of 10% in the Caucasian population and results in a receptor protein that is truncated and not expressed at the cell surface. CCR5Delta32 homozygous individuals are apparently normal but resistant to infection with R5 HIV-1. In two individuals homozygous for CCR5Delta32, who had been repeatedly exposed to CCR5-expressing blood cells through sexual activity, we have identified antibodies to CCR5 that bound specifically to the surface of CCR5-expressing cell lines. Serum from these individuals, in contrast to serum from CCR5(+/+) individuals, competed with radiolabeled RANTES for binding to the CCR5 receptor and inhibited infection of peripheral blood mononuclear cells with R5, but not X4, primary isolates of HIV-1. The identified human antibodies to CCR5 define an alloantigen that may cause allograft rejection in a mismatch situation even in individuals with no history of blood transfusions or i.v. drug abuse.

Alleles↗

PubMed1998

[Molecular cytogenetic study on four human esophageal cancer cell lines].

OBJECTIVE: To investigate the possible involvement of chromosome abnormalities in pathogenesis of human esophageal cancer. METHODS: Four cell lines of human esophageal cancer (EC) established in our laboratory were analysed using interphase fluorescence in situ hybridization (FISH), chromosome painting technique and comparative genomic hybridization (CGH). RESULTS: Chromosome gain of 1,2,3,8,16, 17, and 20 was found in the four cell lines, and loss of chromosome Y in cell line EC8712, EC8733 and EC8501 was noted. Other frequent changes were partial deletion of 1p, translocation of 2q and amplification of 5p in all 4 cell lines, and amplification of 8q and 13q in EC8733 and deletion of 17p in EC8712. CONCLUSION: The data suggest that nonrandom chromosome aberrations may play an important role in the pathogenesis of human esophageal cancer.

Adult↗

PubMed1998

Regulation of system A amino acid transport in 3T3-L1 adipocytes by insulin.

The insulin-stimulated uptake of 2-(methylamino)isobutyric acid (MeAIB), a nonmetabolizable substrate for system A, in 3T3-L1 adipocytes was investigated. As cells took on a more adipogenic phenotype, the insulin-stimulated versus the saturable basal MeAIB uptake increased by 5-fold. The induced transport activity showed properties characteristic of system A, with a Km value of 190 microM. The half-life of the induced system A activity was independent of de novo mRNA and protein synthesis and was not accelerated by ambient amino acids, therefore, it was mechanistically distinct from the previously described adaptive and hormonal regulation of system A. Inhibition of mitogen-activated protein kinase kinase by PD98059, Ras farnesylation by PD152440 and B581, p70(S6K) by rapamycin, and phosphatidylinositol 3-kinase (PI 3'-K) by wortmannin and LY294002 revealed that only wortmannin and LY294002 inhibited the insulin-induced MeAIB uptake with IC50 values close to that previously reported for inhibition of PI 3'-K. These results suggest that the Ras/mitogen-activated protein kinase and pp70(S6K) insulin signaling pathways are neither required nor sufficient for insulin stimulation of MeAIB uptake, and activation of PI 3'-K or a wortmannin/LY294002-sensitive pathway may play an important role in regulation of system A transport by insulin in 3T3-L1 cells.

3T3 Cells↗

PubMed1998

Natural killer cell depletion fails to influence initial CD4 T cell commitment in vivo in exogenous antigen-stimulated cytokine and antibody responses.

The role played by NK- and NK1.1-expressing T cells in CD4 T cell activation and induction of immune responses in vivo is controversial. These effector cells of the innate immune response are hypothesized to play a pivotal role in shaping initial T cell activation, with some groups reporting that classical NK cells are required for optimal Th1-like T cell activation, and others supporting a role for NK1.1+ alphabeta T cells in Th2 generation. Here, we examine the impact of in vivo NK cell depletion on the development of exogenous Ag-specific cytokine and Ab responses using a murine model of human immediate hypersensitivity. OVA-specific immune responses were induced in 1) C57Bl/6 bg/bg and bg/+ mice, 2) BALB/c mice pretreated with anti-asialoGM1 or control Ab, and 3) C57Bl/6 mice depleted of NK1.1-expressing cells by in vivo administration of anti-NK1.1 mAb PK136. Depletion efficacy was assessed by functional assays and flow cytometric analysis. Each of these approaches indicated that depletion of NK cells and NK1.1+ CD4+ T cells fails to alter the Th1:Th2 balance of Ag-driven cytokine synthesis, as indicated by OVA-stimulated cytokine synthesis in primary bulk culture. Similarly, the kinetics and intensity of effector responses such as OVA-specific IgG2a and IgE synthesis were neither increased nor decreased in any of the three models examined. The results argue that NK cells and peripheral NK1.1+ T cells do not play an essential role in shaping the induction of Ag-specific immune responses to soluble exogenous Ags, the most common class of inhalant allergen.

Animals↗

PubMed1998

DNA adducts in human pancreatic tissues and their potential role in carcinogenesis.

Pancreas cancer is the fourth and fifth leading cause of cancer death for men and women, respectively, in the United States. Although the etiology of this cancer is poorly understood, smoking and dietary fat have been implicated by epidemiological studies. To test the hypothesis that DNA damage derived from carcinogen exposure and diet is involved in pancreatic carcinogenesis, aromatic and lipid peroxidation-related DNA adducts in 13 normal tissues adjacent to tumor and 20 tumors from pancreatic cancer patients were analyzed by 32P-postlabeling. Normal pancreatic tissues from 5 nonpancreatic cancer patients and 19 healthy organ donors served as controls. To correlate the DNA adduct level with patients' characteristics, information on age, sex, body mass index, and smoking status of pancreatic cancer patients were collected from medical records. A significantly higher level of total DNA adducts was detected in pancreatic cancer patients as compared with controls. The mean level of adducts/10(8) nucleotides in adjacent normal pancreatic tissues from pancreatic cancer patients (A tissues) was 102 +/- 21 compared with 39 +/- 6 and 13 +/- 1 in pancreatic tumor tissues (T tissues) and normal pancreatic tissues from controls (C tissues), respectively. Among the adducts observed, one single aromatic adduct (spot 1) was present in 100, 90, and 0% of the A, T, and C tissues, respectively. Two novel clusters of adducts (spots 2 and 3) were observed in 11 of 13, 12 of 20, and 2 of 24 of A, T, and C tissues, respectively, and the presence of these adducts was positively correlated with smoking status. In addition, the previously defined smoking-related diagonal radioactive zone was detected in three A samples only, although 50% (10 of 20) of the patients with pancreatic cancers in this study were ever smokers. Putative lipid peroxidation-related adducts were detected in all samples examined and were significantly higher in A than in T and C samples. Multiple regression analyses showed that body mass index was positively correlated to the levels of spot 1 and the lipid peroxidation-related adducts in A tissues and the total aromatic adducts in tumors. Smoking was also positively correlated to the level of total adducts. These observations are consistent with previous epidemiological findings and support the hypothesis that DNA damage related to carcinogen exposure and lipid peroxidation is involved in human pancreatic carcinogenesis.

Adult↗

PubMed1998

Determination of a safe vascular clamping method for liver surgery: evaluation by measuring activation of calpain mu.

OBJECTIVE: To determine the safest method of hepatic vascular clamping associated with the least ischemia-reperfusion injury of the liver during liver surgery. SETTING: University laboratories. SUBJECTS: Sixty-five adult male Wistar rats. METHODS: The hilar area of the left lateral and median lobes of rat liver was clamped for 10 minutes (group 1), 15 minutes (group 2), or 20 minutes (group 3) followed by 5 minutes of reperfusion. The procedure was repeated for a total period of ischemia of 60 minutes in each group. Control rats underwent laparotomy without vascular clamping. In addition to histological examination, we determined calpain mu activity, a marker of liver injury, by Western blotting using specific antibodies against the intermediate (activated) and proactivated forms of calpain mu. Measurements were performed at the end of ischemia and after 2 hours of reperfusion. We also determined the degradation of talin, an intracellular substrate of calpain mu, by Western blotting. RESULTS: The level of adenosine triphosphate and energy charge at 2 hours after reperfusion did not change after ischemia-reperfusion irrespective of the duration of ischemic cycle. After 60 minutes of intermittent ischemia followed by 2 hours of reperfusion, cell membrane bleb formation, calpain mu activation, and talin degradation were detected in groups 2 and 3 but not in group 1. CONCLUSION: The safest method of hepatic vascular clamping that produces a minimum or no ischemia-reperfusion injury is 60 minutes of 6 cycles of 10-minute vascular clamping interrupted by 5 minutes of reperfusion.

Animals↗

PubMed1998

Benzene exposure, glutathione S-transferase theta homozygous deletion, and sister chromatid exchanges.

Recent studies have shown a strong positive correlation between chromosomal aberrations and future cancer risk. Sister chromatid exchange (SCE) has been widely applied in monitoring early biological effects to assess human genetic risk of cancer at the population level. We studied 45 Chinese workers (23 in the painting workshop of a glass factory with occupational exposure to benzene, and 22 fitters and planers in the punching and planing machine workshops of a nearby shipyard without such an exposure) to examine the association between occupational exposure to benzene and SCE frequency in peripheral blood lymphocytes. We also sought to investigate whether the glutathione S-transferase class theta gene (GSTT1) affects individual susceptibility to cytogenetic damage induced by in vivo exposure to benzene or in vitro exposure to diepoxybutane. The time-weighted average concentrations of benzene were 0.71 ppm in the exposed group and 0.03 ppm in the non-exposed group. Controlling for age, gender and educational level, cigarette smoking was significantly associated with increased SCE frequencies (P < 0.05), while GSTT1 genotype was significantly associated with DEB-induced SCEs (P < 0.01). There was no relationship between benzene exposure and baseline or DEB-induced SCEs. After stratification by smoking status, the GSTT1 deletion was a significant predictor of DEB-induced SCEs for both smokers (P < 0.05) and nonsmokers (P < 0.01). A significant benzene-GSTT1 interaction was found in nonsmokers (P < 0.05). Our study suggests that GSTT1 is an important determinant of heterogeneity in individual susceptibility to chromosomal damage associated with exposure to benzene.

Adult↗

PubMed1998

Changes in TGF-beta receptors of rat hepatocytes during primary culture and liver regeneration: increased expression of TGF-beta receptors associated with increased sensitivity to TGF-beta-mediated growth inhibition.

To clarify the role of transforming growth factor-beta (TGF-beta) and its receptors in hepatocyte growth, we studied the expression of TGF-beta1 and its receptors and the sensitivity to growth inhibition by TGF-beta1 protein in rat hepatocytes derived from resting and regenerating livers. In hepatocytes derived from resting livers, mRNAs for TGF-beta type II receptor (TbetaR-II), insulin-like growth factor-II/mannose 6-phosphate receptor (IGF-II/M-6-PR), and TGF-beta1 increased with time in primary culture. The cell surface TGF-beta receptor proteins (TbetaR-I, II, and III), examined by the receptor affinity-labeling assay using 125I-TGF-beta1, also increased, especially after 48 hr of culture. Hepatocytes were more sensitive to inhibition of DNA synthesis, when the TGF-beta1 protein was added at later times in culture, corresponding to the presence of increased TGF-beta receptors. In hepatocytes from regenerating livers after a partial hepatectomy (PH), an increase of TbetaR-I, TbetaR-II, TbetaR-III, IGF-II/M-6-PR, and TGF-beta1 mRNAs was found, compared with hepatocytes from resting livers. Similarly, using TGF-beta receptor affinity-labeling assay, hepatocytes from PH livers were found to have an increase in TbetaR-I, II, and III proteins, with a peak at 4 days post-PH, compared with hepatocytes from resting livers. When TGF-beta1 protein was added for a short period (6 or 24 hr) after cell attachment to hepatocyte cultures, it inhibited DNA synthesis more effectively in hepatocytes from regenerating compared with resting livers. Our results show that hepatocyte TGF-beta receptors and sensitivity to growth inhibition by TGF-beta1 protein change together and are modulated during liver regeneration, as well as during the conditions of primary culture.

Activin Receptors, Type I↗

PubMed1998

Can staff training reduce behavioural problems in residential care for the elderly mentally ill?

The effect of a brief in-service training programme on the psychosocial management of behavioural disturbance in residential care is described. Although the incidence of problematic behaviour did not change 3 months after training, staff in the experimental homes reported a significant improvement in their management of problematic behaviour, as compared to the control home. However, these effects were not maintained a year later. The importance of post-training supervision and the sociocultural context of the home in the maintenance of psychosocial intervention in residential settings is discussed.

Aged↗

PubMed1998

Molecular genetic analysis of a novel Parkin gene in Japanese families with autosomal recessive juvenile parkinsonism: evidence for variable homozygous deletions in the Parkin gene in affected individuals.

Autosomal recessive juvenile parkinsonism (AR-JP) is a distinct clinical and genetic entity characterized by selective degeneration of nigral dopaminergic neurons and young-onset parkinsonism with remarkable response to levodopa. Recently, we mapped the gene locus for AR-JP to chromosome 6q25.2-q27 by linkage analysis and we identified a novel large gene, Parkin, consisting of 12 exons from this region; mutations of this gene were found to be the cause of AR-JP in two families. Now we report results of extensive molecular analysis on 34 affected individuals from 18 unrelated families with AR-JP. We found four different homozygous intragenic deletional mutations, involving exons 3 to 4, exon 3, exon 4, and exon 5 in 10 families (17 affected individuals). In addition to the exonic deletions, we identified a novel one-base deletion involving exon 5 in two families (2 affected individuals). All mutations so far found were deletional types in which large exonic deletion accounted for 50% (17 of 34) and the one-base deletion accounted for 6% (2/34); in the remaining, no homozygous mutations were found in the coding regions. Our findings indicate that loss of function of the Parkin protein results in the clinical phenotype of AR-JP and that subregions between introns 2 and 5 of the Parkin gene are mutational hot spots.

Amino Acid Sequence↗

PubMed1998

The inhibitory effect of interleukin 1beta on rat hepatocyte DNA synthesis is mediated by nitric oxide.

Interleukin 1beta (IL-1beta) and nitric oxide (NO) have potent growth-regulatory effects on different cell types. We found that epidermal growth factor-induced DNA synthesis in primary cultures of adult rat hepatocytes was inhibited by NO when it was provided by addition to the cultures of S-nitroso-N-acetyl-penicillamine (SNAP), an NO donor, as well as by addition of IL-1beta in a dose-dependent manner. IL-1beta also induced NO production and inducible NO synthase (iNOS) gene expression. The inhibition of DNA synthesis by IL-1beta was completely abrogated when NO production was inhibited by N-monomethyl-L-arginine (NMA), a competitive inhibitor of iNOS. IL-1beta-receptor antagonist (IL-1ra), which interferes with the interaction of IL-1beta with target cells, also abolished the inhibitory effects of IL-1beta on hepatocyte DNA synthesis as well as IL-1beta-induced iNOS gene expression. We also found that hepatocyte DNA synthesis inhibition by IL-1beta was completely antagonized by providing deoxynucleosides to bypass the block in ribonucleotide reductase, a rate-limiting step in DNA synthesis, thus implicating this enzyme in the mechanism of growth inhibition by IL-1beta. These experiments extended prior observations on the growth-inhibitory actions of IL-1beta on hepatocyte DNA synthesis, involving the IL-1beta receptor, NO production, and ribonucleotide reductase.

Animals↗

PubMed1998

High-efficacy thymidine kinase gene transfer to ovarian cancer cell lines mediated by herpes simplex virus type 1 vector.

In this report, a replication-defective herpes simplex virus type 1 (HSV-1) vector has been employed to deliver the Escherichia coli LacZ and HSV thymidine kinase (HSVtk) genes to six human ovarian carcinoma cell lines and the efficacy of gene transfer compared to that of adenoviral vectors in vitro. The transduction efficiency of the LacZ-containing virus TOZ.1 was evaluated qualitatively and quantitatively following infection of the different ovarian cancer cell lines. The therapeutic ability of the HSV-T3 vector, which contains the HSVtk gene, was additionally investigated in comparison to the AdCMVHSVTK. Our results show that HSV-1-mediated gene transfer is quantitatively superior to adenoviral vector in five of the six ovarian cancer cell lines at a 100-fold lower dose in vitro. Our preliminary studies suggest that HSV-1 may be a promising alternative vector for ovarian cancer gene therapy.

Cell Division↗