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Biomedical subjects

M Wang

Publications and source records attributed to M Wang.

At least 937 records · Page 52Linked to original sources
PubMed1992

Detection of point mutations of the phenylalanine hydroxylase gene and prenatal diagnosis of phenylketonuria.

The known mutant alleles of the human phenylalanine hydroxylase (PAN) gene were analyzed in 25 phenylketonuria (PKU) families from North China by using polymerase chain reaction and allele-specific oligonucleotide dot blot hybridization techniques. The results showed that the six mutations analyzed accounted for 62% of all PKU genes. The three most frequent mutations were R243Q, R413P and Y204C. Seven prenatal gene diagnoses were carried out in 6 PKU families and were confirmed after birth or by examination of aborted materials.

Base Sequence↗
PubMed1992

[Modification and expression of insecticidal protein structural gene of Bacillus thuringiensis var. aizawai 7-29].

The regulative region (181bp) and the fifth toxic active domain (217bp) were removed from the insecticidal protein gene of Bacillus thuringiensis var. aizawai 7-29. After the synthesis of the adaptor (15bp) that contains initiation codon (ATG) and the PCR synthesis of the fifth toxic active domain (229bp) that contains stop codon (TAA), were inserted into on 5' truncated and 3' truncated of the coding fod N-terminal peptid's DNA fragment, that to become a modified structural gene. The modified structural gene can be play initiatic translation-function and stop translation-function during translation of insecticidal protein. The insecticidal protein was determined by western blotting, showed the expression of modified structural gene in Escherichia coli JM 103. The bioassay of insecticidal proteins showed the 3' truncated and 5' truncated of insecticidal gene was higher toxic active than the 3' truncated of insecticidal gene in Escherichia coli JM 103.

Bacillus thuringiensis↗
PubMed1992

[erb-B oncogene in human oral squamous cell carcinomas].

erb-B gene is an oncogene from avian leukosis virus. The carcinogenic capability of erb-B is due to the close similarity of expressional proteins to the epidermal growth factor receptor (EGFr). In this study the amplification and the over-expression of erb-B were found in human oral squamous (cell carcinomas by DNA and RNA dot blot hybridization). Results showed that erb-B was correlated with the oral epidermoid tumors but not with group of non-epidermoid tumors in the head and neck region. Southern blotting analysis showed that there were rearrangement of erb-B gene in the tumor genosomes, which is perhaps one of the ways to activate the proto-oncogene of erb-B.

Avian Leukosis Virus↗
PubMed1992

[Frequencies of 6 known mutations in phenylalanine hydroxylase gene and their application in prenatal gene diagnosis].

The known mutant alleles of human phenylalanine hydroxylase gene were analyzed in 25 phenylketonuria (PKU) families from North China by polymerase chain reaction combined with allele-specific oligonucleotide dot hybridization techniques. The results showed that the six mutation accounted for 62% of all PKU genes. The three most frequent mutations were Arg243-->Gln in exon 7, Arg413-->Pro in exon 12 and Tyr204-->Cys in exon 6. They accounted for 24%, 18% and 16% respectively of all PKU alleles. The frequencies of Arg111-->Ter mutation in exon 3, Tyr356-->Ter mutation in exon 11 and Trp326-->Ter mutation in exon 10 were somewhat lower in North China. They accounted for 4% of all PKU alleles. Among these 25 PKU families, prenatal gene diagnosis was possible in 10 families. In 11 families, 50% exclusive diagnosis was possible. Prenatal gene diagnosis was performed and confirmed in 2 families.

Alleles↗
PubMed1992

[Factors in recurrence after curative resection of rectal cancer].

Data on 409 Patients who had a curative resection for rectal cancer at the National Taiwan University Hospital between 1977 and 1989 were analysed to determine the independent effect on recurrence. In our series, the total operative mortality rate was 1.7% and the resectability rate was 88.1%. For these cases who received curative resection, the overall 5-year survival rate was 62.6%. The 5-year survival rate varied according to the Dukes' stage: stage A, 96.4%; stage B, 73.3% and stage C, 39.6%. The total recurrence rate after curative resection was 35.9%, including local recurrence 18.3%, systemic recurrence 12.0%, and combined recurrence 5.6%. According to Dukes' staging system, the recurrence rate for stage A, B and C were 0%, 22.4% and 63.8%, respectively. We used Cox's regression model to analyse the patients characteristics and pathological variables on recurrence and to assess the independent influence of each when all other factors were held constant. The pathological stage of the cancer had the strongest association. Other variables found to have an independent yet significant importance, were CEA level and tumor size. The identification of the patient group, at a high risk of recurrence, might promote a more judicious selection for surgical procedure and trials of adjuvant therapy.

Adult↗
PubMed1992

[Studies on plasma beta-thromboglobulin, thromboxane A2, prostaglandin I2 concentration and platelet count in liver diseases].

We measured blood platelet count and plasma beta-thromboglobulin concentration in 67 patients with acute or chronic liver diseases. Plasma TXB2 and 6-keto-PGF1a concentration were also measured in these patients. The results showed that blood platelet count of less than 100 x 10(9)/L was found in 14% of the patients with acute hepatitis, 23% with chronic hepatitis, 67% with hepatic cirrhosis but without splenectomy and 40% with primary liver carcinoma. Platelet count is lowest in patients with hepatic cirrhosis without splenectomy but normal in patients with hepatic cirrhosis after splenectomy. Plasma beta-TG concentration increased in patients with acute or chronic liver diseases. A negative correlation was found between beta-TG concentration and platelet count in chronic liver diseases. It is suggested that platelet is in activated state in vivo and this may be one of the important reasons for both decrease of platelet count and impairment of platelet function. Plasma TXB2 concentration increased in chronic liver diseases, while plasma 6-keto-PGF1a concentration decreased. The balance between TXA2 and PGI2 is upset; this may be an important mechanism for activation of platelets in vivo.

6-Ketoprostaglandin F1 alpha↗
PubMed1992

[Effects of ginseng volatile oil on cytochemical components of SGC-823 gastric carcinoma in cell culture].

After 24, 48 and 72 hours' treatment of cells of SGC-823 gastric carcinoma in cell cultures with ginseng volatile oil, glycogen, succinate dehydrogenase and DNA in single cells were measured quantitatively with MPV2 microscope photometer. The results show that the inhibition of cancer cell growth by ginseng volatile oil may be due to the action of metabolism of DNA, carbohydrates and energy.

DNA, Neoplasm↗
PubMed1992

[Thixotropic properties of whole blood in children with congenital heart disease].

The thixotropic parameters of whole blood in two groups of children with congenital heart disease (CHD) were measured. Group 1. cyanotic heart disease (CCHD), 20 cases; Group 2. acyanotic heart disease (ACHD), 30 cases. Fifty healthy children were controls matched with the patients in sex and age. Their thixotropic parameters were compared; the paired t-test was used. In the children with CCHD, the hematocrit (HCT), the yield stress (tau 0) the Newtonian contribution of viscosity (mu), the equilibrium value of the structural parameter (A), the apparent viscosity at 2.37 sec-1 (eta s) and the Non-Newtonian contribution of viscosity (eta s-mu) were significantly higher than those in corresponding control groups. In the children with ACHD, only the values of tau 0, eta s-mu, and eta s were higher than those in control groups. All of the thixotropic parameters in CCHD group were significantly higher than those in ACHD group. Thus we described quantitatively CHD in terms of thixotropy of blood. The thixotropic parameters of blood could be used as indexes of severity for pathologic changes of CHD.

Adolescent↗
PubMed1992

[Expression and distribution of catechol 2,3-dioxygenase in Escherichia coli].

A series of new plasmids containing xylE gene was constructed based on the shuttle plasmid pTG 402 between E. coli and B. subtilis. The expressed xylE gene product catechol 2,3-dioxygenase (CatO2ase) was measured for its output and distribution, and analysed for its structural hydrophobicity and hydrophilicity. It was demonstrated that the output of CatO2ase was relative to plasmids, host cells, culture time and with or without induction. The enzyme didn't have features of excretional proteins and was mostly distributed inside the cells though a little could be detected in culture medium. It can be used as a selective marker, indicator and monitor in the study of genetic engineering. This research also provides a scientific basis for eliminating pollution of aromatic hydrocabonic compounds with genetic engineering bacteria.

Base Sequence↗
PubMed1991

Regulation of kinesin expression and type IV collagenase secretion in invasive human prostate PC-3 tumor sublines.

PC-3 human prostatic tumor sublines have been previously isolated which exhibit striking differences in their invasive and metastatic phenotypes. This work has been extended here to measure and compare the levels of kinesin, a microtubule-dependent translocator molecule, in the PC-3 sublines. Western blots, slot blots, radiolabeling, and immunoprecipitation analysis showed that kinesin was expressed in the highly invasive and metastatic sublines at levels which were elevated above the base-line levels observed in the parent PC-3 cells. In comparison, kinesin was not expressed in detectable amounts in the noninvasive cell lines. The conditioned medium of the metastatic PC-3 sublines contained a heat- and trypsin-sensitive protein which exhibited a dosage-dependent capacity to stimulate increased kinesin expression, type IV collagenase secretion, and invasion of Matrigel by the metastatic sublines. The noninvasive sublines failed to secrete a similar stimulatory factor(s) or respond to the conditioned medium of metastatic sublines. Various growth factors and cytokines tested (platelet-derived growth factor, epidermal growth factor, insulin-like growth factor, formylmethionineleucinephenylalanine) had no significant effect on either kinesin expression or protease secretion and invasion. Pertussis toxin blocked the stimulatory effects of the conditioned medium, but other agents known to interfere with adenylate cyclase pathways (i.e., cholera toxin, forskolin, 8-bromoadenosine) failed to block stimulation. The data show for the first time that kinesin, protease secretion, and the resulting invasion process may be regulated in a coordinated manner by an autocrine factor(s) which activates G-protein-dependent processes.

3T3 Cells↗
PubMed1991

Induction of tissue-type plasminogen activator by ionizing radiation in human malignant melanoma cells.

Two differently timed extracellular and intracellular enzymatic and mRNA peaks of tissue-type plasminogen activator (t-PA) were induced following ionizing radiation. The first peak appeared within 10 min following X-irradiation but rapidly declined. The appearance of early t-PA mRNA transcripts and enzymatic activity were not prevented by actinomycin D treatment. In contrast, cycloheximide prevented the early, minor enzymatic induction peak of t-PA. Stabilization of t-PA mRNA transcripts appears to be an early initial response of human cells to ionizing radiation, since the synthesis of new mRNA transcripts within the first 30 min was not observed via nuclear run-on analyses. Nearly 12 h following X-irradiation, a second major enzymatic peak of t-PA was observed. Cycloheximide or actinomycin D treatments blocked the later t-PA response. t-PA mRNA levels were induced greater than 100-fold in 4 h by ionizing radiation as assayed via Northern or nuclear run-on analyses. During the major induction period, t-PA mRNA transcripts reached their maximum levels at 4-8 h, and intracellular enzyme levels accumulated 6-8 h after X-irradiation. Unirradiated U1-Mel cells demonstrated only low basal levels of t-PA mRNA and enzymatic activity. Similar induction responses were found following UV-irradiation or 12-O-tetradecanoyl-phorbol-13-acetate (PMA) treatments. Normal human fibroblast (i.e., GM 2936B, GM2907A, and IMR-90) cells also demonstrated the induction of t-PA, although only one later enzymatic peak was detected. The induction of t-PA mRNA levels and intracellular and extracellular enzymatic activities for these cells were 50-fold lower than with U1-Mel cells given equitoxic doses of X-rays. Differential expression of t-PA in some tumor as compared to normal tissues may be utilized in future chemotherapeutic regimens.

DNA↗
PubMed1991

Abscisic acid induces a cytosolic calcium decrease in barley aleurone protoplasts.

Cytosolic calcium concentrations (Cai) of barley aleurone protoplasts after stimulation with the plant hormone abscisic acid (ABA) were measured by using the calcium-sensitive fluorescent dye Indo-1. The measured basal Cai is about 200 nM. Stimulation with ABA induces a strong dose-dependent decrease in Cai to a minimal value of about 50 nM. This decrease occurs within 5 s. The Ca2+ antagonists La3+ and Cd2+ inhibit the ABA-induced Cai decrease in a dose-dependent manner, while the Ca2+ channel blockers verapamil and nifedipine give no inhibition. The induction of Cai decrease by ABA is consistent with activation of the plasma membrane Ca2(+)-ATPase by ABA. The possible role of this ABA-induced Cai decrease in ABA signal transduction and in counteracting the effects of gibberellic acid are discussed.

Abscisic Acid↗
PubMed1991

Selective inhibition of natural killer but not natural cytotoxic activity in a cloned cell line by delta-9-tetrahydrocannabinol.

Natural killer (NK) and natural cytotoxic (NC) activities are spontaneously generated against certain tumors in vitro and their contribution to tumor immunity is being extensively investigated. We report here that the interleukin-2 (IL-2)-dependent murine cell line, NKB61A2, which we recently found to express both NK and NC functions, can be modulated selectively by 9 delta-tetrahydrocannabinol (THC). THC, a major psychoactive metabolite of marijuana, could significantly inhibit NK activity without altering NC activity in NKB61A2 cells. Inhibition of NK function occurred at a post-binding stage because effector/target conjugation was unaffected by THC. With regard to NC function, neither the cytotoxic activity of the cells nor release of tumor necrosis factor was interrupted by THC. Therefore, THC may provide a useful tool for dissociating the mechanism of NK and NC activities within a single population of cells.

Animals↗
PubMed1991

Evaluation of a psychophysiological model of classical fear conditioning in anxious patients.

Skin conductance variables have been compared in 30 anxious patients and 30 controls to investigate the extent to which anxiety is associated with increased autonomic arousal, reduced habituation or enhanced aversive conditioning. Skin conductance level, variability (spontaneous fluctuations) and response amplitudes to tones were significantly greater in patients than controls. Habituation of skin conductance responses to a series of ten innocuous tones (80 dB, 1 s) did not differ between the groups. Aversively conditioned skin conductance responses were measured to a further series of ten tones after a conditioning trial in which a loud white noise (100 dB) followed tone 11. All subjects showed enhanced (conditioned) responses to the tones after the conditioning trial, but patients did not show greater conditioning than controls. The results indicate that anxious neurotic out-patients have greater sweat gland activity and reactivity than controls but fail to demonstrate differences in central mechanisms of habituation or conditioning.

Acoustic Stimulation↗