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Biomedical subjects

M Wang

Publications and source records attributed to M Wang.

At least 685 records · Page 38Linked to original sources
PubMed1996

Apoptotic inhibition of head and neck squamous cell carcinoma cells by tumor necrosis factor alpha.

OBJECTIVES: To evaluate the effect and mechanism of action of tumor necrosis factor alpha (TNF-alpha) on head and neck squamous cell carcinoma (HNSCC) cell lines. Specifically, to find out whether TNF-alpha induces apoptotic (programmed) cell death. DESIGN: Cytotoxicity and kinetics were evaluated through the use of a methylene blue colorimetric assay. The mechanism of cell death was evaluated through gel electrophoresis of extracted DNA, double-stranded DNA fragmentation, and Hoechst 33342-propidium iodide double staining. TARGET CELLS: Four HNSCC cell lines were investigated: UMSCC-1, UMSCC-8, UMSCC-19, and CAL-27. RESULTS: Tumor necrosis factor alpha at a concentration of 10000 U/mL induced cytotoxic effects in all four cell lines with varying sensitivities. Significant cytotoxic effects required 3 to 4 days of exposure to TNF-alpha. Further experiments demonstrated that TNF-alpha induced double-stranded DNA fragmentation of targets, which preceded the detection of actual cytotoxic effects. Treated HNSCC cell lines had their DNA fragmented into a ladder pattern of endonucleolytic cleavage of multiples of 180 to 200 base pairs, consistent with apoptosis. Propidium iodide-Hoechst 33342 double staining confirmed that TNF-alpha-induced nuclear alterations precede permeabilization of the plasma membrane, supporting cell death in these tumor cells by apoptosis. CONCLUSION: Tumor necrosis factor alpha exposure results in variable cytotoxic reactions in HNSCC cell lines, with DNA fragmentation preceding significant cell death. The mechanism of cell death is apoptosis, with typical morphological features. Further studies are needed to better elucidate the role of TNF-alpha in the treatment of in vivo HNSCC.

Apoptosis↗
PubMed1996

Genotypes of human polyomaviruses in urine samples of pregnant women in Taiwan.

The viral DNA of human polyomaviruses JC virus (JCV) and BK virus (BKV) was detected by the polymerase chain reaction (PCR) in urine samples from 31 pregnant women in Taiwan. A pair of appropriate primers amplified both JCV and BKV DNA of the regulatory region simultaneously in PCR. An oligonucleotide probe homologous to both JCV and BKV regulatory region was used subsequently to detect the viral DNA by Southern blotting after PCR amplification. Approximately 36% of the examined urine samples were human polyomavirus positive. The genotypes of JCV and BKV were determined by DNA sequencing of their regulatory regions. Besides CY archetype, a new strain (Taiwan-1) of JCV with a pentanucleotide (GGGAA) deletion and a new strain (Taichung-1) of BKV with two nucleotide alterations within the regulatory region were found in the urine samples. Eight of the examined samples were JCV infected, one was BKV infected, and two were JCV and BKV mix-infected. The JCV positive individuals were infected by CY archetype and Taiwan-1 strain equally. However, Taichung-1 strain was the only BKV strain found in the BKV positive individuals.

BK Virus↗
PubMed1996

Different genotypes of human polyomaviruses found in patients with autoimmune diseases in Taiwan.

We have assayed for the presence of human polyomaviruses in urine of autoimmune disease patients, such as systemic lupus erythematosus (SLE), Sjogren's syndrome (SS), rheumatoid arthritis (RA), or dermatomyositis/polymositis (DM/PM), by PCR. The results indicate that approximately 40% of patients were JCV positive and 15% of the JCV positive patients were also infected by BKV at the same time according to Southern blot and DNA sequencing of the PCR products. Interestingly, the JCV present in autoimmune diseases patients were Taiwan-1, Taiwan-2, and Taiwan-3 strains with pentanucleotide-A (GGGAA) and/or -B (AAAGC) deletions within the regulatory region. In addition, BKV found in the examined samples were Taichung-1 and Taichung-2 strains. Taichung-1 had two nucleotide alterations and Taichung-2 had six nucleotide differences within the regulatory region when compared to WW BKV archetype. Although the examined autoimmune diseases patients included RA, SLE, PM, DM, and SS patients, there appears to be no correlation between disease and virus strains. However, Taiwan-2 strain JCV with two copies of pentanucleotide-A deletion was present in the patient with the longest period of immunosuppressive medication.

Autoimmune Diseases↗
PubMed1996

Long-term outcome after surgery for asymptomatic small hepatocellular carcinoma.

The subjects of this study were 48 asymptomatic patients who had surgery for small hepatocellar carcinoma (HCC). There were 42 men and six women with mean (s.d.) tumour size of 3.31 (1.46) cm and age 55.0 (7.4) years. Follow-up was for a minimum of 10 years. The main concern of this study was a univariate analysis of factors that might affect long-term survival after surgery, which was 50 per cent at 5 years and 31 per cent at 10 years. A high incidence of recurrent HCC (37 of 48 patients) was observed but reoperation further prolonged life in some cases. The significant prognostic factors detected by multivariate analysis were: histological classification, functional liver reserve and histology of the resection margin. Tumour size, gross appearance of tumour, presence of liver cirrhosis, serum alpha-fetoprotein level, age or sex did not affect the prognosis.

Carcinoma, Hepatocellular↗
PubMed1996

In vivo direction of CD4 T cells to Th1 and Th2-like patterns of cytokine synthesis.

Factors that influence the initial development, and continued maintenance, of Th1 or Th2-like responses in vivo play a pivotal role in determining immune effector mechanisms and clinical outcome. Here, we review recent developments in this area with particular emphasis on (i) the ability of chemically modified exogenous antigens to preferentially activate Th1-dominated responses in vivo and (ii) the role played by NK cells in initial commitment of naive exogenous antigen-specific T cells to Th1 or Th2-like cytokine synthesis. We find that NK cell depletion of naive mice prior to immunization with OVA (which induces balanced Th0 like responses), or a high Mr polymer (that preferentially elicits OVA-specific Th1-dominated responses), fails to influence the development of cytokine or specific antibody responses. The results argue that NK cells do not play an essential role in shaping induction of immune responses to exogenous antigens, the most common class of inhalant allergen.

Animals↗
PubMed1996

Apoptosis in barley aleurone during germination and its inhibition by abscisic acid.

During germination of barley grains, DNA fragmentation was observed in the aleurone. The appearance of DNA fragmentation in the aleurone layer, observed by TUNEL staining in aleurone sections, started near the embryo and extended to the aleurone cells far from the embryo in a time dependent manner. The same spatial temporal activities of hydrolytic enzymes such as alpha-amylase were observed in aleurone. DNA fragmentation could also be seen in vitro under osmotic stress, in isolated aleurone. During aleurone protoplast isolation, a very enhanced and strong DNA fragmentation occurred which was not seen in protoplast preparations of tobacco leaves. ABA was found to inhibit DNA fragmentation occurring in barley aleurone under osmotic stress condition and during protoplast isolation, while the plant growth regulator gibberellic acid counteracted the effect of ABA. Addition of auxin or cytokinin had no significant effect on DNA fragmentation in these cells. To study the role of phosphorylation in ABA signal transduction leading to control of DNA fragmentation (apoptosis), the effects of the phosphatase inhibitor okadaic acid and of phenylarisine oxide on apoptosis were studied. We hypothesize that the regulation of DNA fragmentation in aleurone plays a very important role in spatial and temporal control of aleurone activities during germination. The possible signal transduction pathway of ABA leading to the regulation of DNA fragmentation is discussed.

Abscisic Acid↗
PubMed1996

Adenoviral-mediated delivery of herpes simplex virus thymidine kinase results in tumor reduction and prolonged survival in a SCID mouse model of human ovarian carcinoma.

The herpes simplex virus thymidine kinase gene is the most widely utilized toxin for selective killing of carcinoma cells. Expression of the viral thymidine kinase gene renders cells sensitive to the toxic effects of nucleoside analogs such as ganciclovir. An advantage of this system is the "bystander effect" whereby thymidine kinase transduced tumor cells elicit a toxic effect on surrounding nontransduced tumor cells. Ovarian carcinoma appears to be an ideal candidate for gene therapy as the majority of women present with advanced stage disease, have poor prognosis for long-term survival and have the disease confined within the peritoneal cavity. Therefore the utility of an adenoviral vector to elicit an in vitro bystander effect in ovarian carcinoma cells and the therapeutic efficacy of such a system in vivo was undertaken. Immunocompetent animals were utilized to determine the maximum dose of adenovirus that could be administered without any undesirable side effects and that preimmunization had no effects on subsequent challenge. SCID mice were orthotopically transplanted with human ovarian carcinoma cells and, after establishment of tumor, given a recombinant adenovirus expressing either the herpes simplex virus thymidine kinase or the Escherichia coli beta-galactosidase gene. Half the animals from each viral group were treated with either a ganciclovir regiment (50 mg/kg daily for 14 days) or an equal volume of serum-free media. A subset of mice were killed following drug treatment and analyzed for tumor reduction. The remaining animals were followed daily for survival. The animals treated with the recombinant adenovirus expressing the herpes simplex virus thymidine kinase gene and ganciclovir had significant reduction in overall tumor burden and demonstrated statistically significant prolongation in overall survival.

Adenoviridae↗
PubMed1996

Effects of tetrandrine on cardiac noradrenaline release evoked by electrical stimulation.

The effects of tetrandrine (TD) on endogenous cardiac noradrenaline (NA) release evoked by electrical stimulation were investigated in perfused guinea pig hearts. The overflow of cardiac NA and its intraneuronal metabolite 3,4-dihydroxyphenylethyleneglycol (DOPEG) were determined by high pressure liquid chromatography (HPLC). In the presence of TD, the release of NA evoked by either nerve ganglion-stimulation or cardiac field-stimulation was significantly reduced (P < 0.01). The overflow of DOPEG was markedly enhanced (P < 0.01). TD inhibited cardiac endogenous NA release resulting from activation of the sympathetic nerve terminals within the myocardium, and increased the release of DOPEG, indicating that TD could result in a loss of NA from storage vesicles or activate monoamine oxidase in axoplasma, which could be detected by markedly increased DOPEG release. These effects of TD may be associated with its property of calcium antagonist.

Alkaloids↗
PubMed1996

Study on the relationship between cytogenetics and phenotypic effect in Turner's syndrome.

The cytogenetics and clinical stigmata in 5 cases of Turner's syndrome were studied. Three of them were non-mosaic 1(Xq) and two with partial monosome of a X chromosome short are (Xp21), whose DNA replication patterns of inactive X chromosome were analyzed by RBG technique. Results showed that differences between the replication patterns in cases of X chromosome deletion (Xp21) and normal females existed; that the behavior of abnormal X expressed nonrandom inactivation. It was suggested that the phenotype may be closely related with both X chromosome replication pattern and its inactivation behavior, which might be useful in genetic counselling.

Adolescent↗
PubMed1996

Zinc acetate and lyophilized aloe barbadensis as vaginal contraceptive.

Twenty samples of fresh ejaculate, donated by healthy volunteers ranging in age from 20-30 years, were obtained from the Center for Fertility & Cryobiology, University of Missouri, Columbia, Missouri. Average semen volume was 2.49 ml; average sperm motility was 71.32%; and average sperm density was 113.71 x 10(6) /ml. Testing for spermicidal effectiveness of a 1% concentration of zinc acetate, zinc sulfate, zinc chloride, and zinc gluconate proved that only zinc acetate was spermicidal. It appears this is due to the acetate in zinc acetate which may decrease oxygen utilization by sperm. Zinc acetate in vitro was antiviral while lyophilized aloe barbadensis was not. Lyophilized aloe barbadensis at concentrations of 7.5% and 10% proved to be spermicidal due to the multiple micro elements (boron, barium, calcium, chromium, copper, iron, potassium, magnesium, manganese, phosphorus, and zinc) which were toxic to the tail causing instant immobilization. The two compounds did not irritate or cause ulceration of rabbit vaginal epithelium. These results suggest the possibility of using zinc acetate and lyophilized aloe barbadensis as a new, effective and safe vaginal contraceptive.

Acetates↗
PubMed1996

Production of the antigen and the antibody of the JC virus major capsid protein VP1.

The DNA of the major capsid protein VP1 of the human polyomavirus JC virus (JCV), Taiwan-3 strain, was generated from the urine of an autoimmune disease patient by polymerase chain reaction (PRC). The VP1 DNA was cloned into a prokaryotic expression vector, pGEX-4T-1, for expression in E. coli. The nucleotide sequences and the deduced amino acid sequences were determined and compared with the JC virus prototype, Mad-1. Thirty nucleotides were different between these two strains. Six of the altered nucleotides affected amino acid coding and ten of them caused changes in endonuclease recognition sites. The recombinant VPI protein was purified and used to raise monospecific antiserum in rabbit. Recombinant JCV VP1 protein and its monospecific antiserum are important clinical reagents and could possibly be developed as a subunit vaccine and as a serological diagnostic antigen in the future. In addition, the region between amino acid residues 40 and 80 of JCV VP1 is predicted to be an antigenic epitope on the basis of its hydropathy plot and comparison with the VP1 sequences of SV40 and BK virus.

Amino Acid Sequence↗
PubMed1996

Low blood protein heterozygosity in zoo-bred hamadryas baboons.

An electrophoretic study of erythrocyte allozymes and serum proteins representing 32 genetic loci in 32 hamadryas baboons (Papio H.hamadryas) from Cologne and Frankfurt zoos revealed biallelic polymorphism in phosphoglucomutase (PGM), mannose phosphate isomerase (MPI) and transferrin (Tf). Polymorphism amounted to P = 0.097 over 31 loci and observed heterozygosity to H(o) = 0.011, indicating significant reduction from the respective gene diversity parameters encountered in free-living hamadryas baboons. Polygynous mating reduced numbers of heterozygotes at the Tf and the PGM-II loci significantly below Hardy-Weinberg expectations. This results support the importance of active genetic management in programmes for captive breeding and species conservation.

Alleles↗
PubMed1996

Transport of reactive metabolites of procarcinogens between different liver cell types, as demonstrated by the single cell microgel electrophoresis assay.

Procarcinogens have to be activated by specific cytochromes before showing adverse effects. Freshly isolated hepatocytes (parenchymal liver cells, PC) are characterized by a high content of such xenobiotic enzymes and are widely used to investigate chemically induced DNA damage. But in many cases liver tumors caused by indirect acting carcinogens can also originate from non-parenchymal liver cells (NPC). We used freshly isolated rat PC and NPC to demonstrate that only PC have activation capacity when treated in vitro with different genotoxic procarcinogens (N-nitrosodimethylamine, NDMA; vinyl chloride, VC). The alkaline single cell microgel electrophoresis assay was applied to measure the genotoxic activity of the activated compounds. In order to test the hypothesis that reactive metabolites can be transported from PC to NPC, we performed additional in vivo studies as well as studies in which PC were incubated together with NPC, only separated by a dialysis tube (in vitro coincubation). The results indicate that reactive metabolites of both NDMA and VC are stable enough to be transported intercellularly from PC to NPC.

Administration, Inhalation↗
PubMed1996

A new in vitro measurement technique for small three-dimensional joint motion and its application to the sacroiliac joint.

A new experimental technique for the measurement of three-dimensional (3-D), six degrees of freedom motion of a human joint is described. The apparatus consists of a solid cube and an orthogonal frame. Six spring-loaded linear variable differential transformers (LVDTs) are held by the frame in contact with three adjacent orthogonal surfaces of the cube. Three of the six LVDTs are positioned non-colinearly in contact with the first surface of the cube, two with the second surface, and one with the third surface. With the cube mounted on one of the moving bodies of a joint and the frame on the other one relative 3-D motion of the joint can be obtained from the six LVDT measurements based on the rigid body kinematics. An algorithm was developed to compute three Euler rotation angles and the 3-D translational components of a reference point on the body segment. The system was calibrated and applied to an in vitro study of sacroiliac joint motion. It has a rotational accuracy of 0.04 degree (with a S.D. of 0.07 degree) and a translational accuracy of 0.01 mm (with a S.D. of 0.01 mm). The possibility of adding a redundant seventh LVDT has also been explored and improvements in accuracy are reported. The main advantages of this technique are its compact size, accuracy, and low overall cost.

Biomechanical Phenomena↗
PubMed1996

Treatment of 100 patients with primary amyloidosis: a randomized trial of melphalan, prednisone, and colchicine versus colchicine only.

PURPOSE: A clinical trial designed to test whether treatment with melphalan, prednisone, and colchicine (MPC) is superior to colchicine (C) alone was performed in patients with primary amyloidosis (AL), a nonmalignant plasma cell dyscrasia. PATIENTS AND METHODS: Patients were randomized to MPC or C with stratification according to sex, time from diagnosis to study entry (ie, less than 3 months or 3 to 12 months), and dominant organ system involvement (ie, cardiac, renal, neurologic, or others). Data were gathered monthly from patients, quarterly from physicians, and annually in the Clinical Research Center. One hundred consecutive patients with AL amyloidosis admitted between 1987 and 1992 who met eligibility requirements were treated and followed for a minimum of 18 months. Fifty patients (group A) received daily oral colchicine and 50 patients (group B) received cycles of oral melphalan and prednisone every 6 weeks for 1 year as well as colchicine. RESULTS: The principal outcome measure was median survival, which was compared in the two treatment groups and in the subgroups. The overall survival of all patients from study entry was 8.4 months. Comparing group A (C) to group B (MPC), the survival was 6.7 months versus 12.2 months (P = 0.087). Both treatment groups had poor survival for patients in the cardiac subgroup, longest survival in the renal group, and significant differences favoring MPC treatment only in patients whose major system manifestations were neurologic (P = 0.037) or other (P = 0.007). Multivariate analysis showed a strongly significant treatment effect (P = 0.003) and improved survival associated with not having cardiac or gastrointestinal involvement. CONCLUSIONS: MPC was advantageous for patients whose major manifestations of amyloid disease were other than cardiac or renal. Better survival regardless of treatment was noted in patients for whom a satisfactory supportive treatment such as transplant or dialysis exists for their organ failure.

Amyloidosis↗
PubMed1996

Single neuron local rational arithmetic revealed in phase space of input conductances.

We present a phase space analysis to explore the potential of single neuron local arithmetic operations on its input conductances. This analysis was conducted first by deriving a rational function model of local spatial summation by using the equivalent circuits for steady-state membrane potentials. It is shown that developed functional phases exist in the space of input conductances, where a single neuron's local operation on input conductances can be described in terms of a set of well-defined arithmetic functions. It is further suggested that this single neuron local rational arithmetic is programmable, in the sense that the selection of these functional phases can be effectively instructed by presynaptic activities. This programmability adds the degree of freedom in a single neuron's ability to process the input information.

Cell Compartmentation↗