Showing papers by "Jian Wang published in 1997"

Ataxia telangiectasia mutant protein activates c-Abl tyrosine kinase in response to ionizing radiation

Abstract: Ataxia telangiectasia (AT) is a rare human autosomal recessive disorder with pleiotropic phenotypes, including neuronal degeneration, immune dysfunction, premature ageing and increased cancer risk. The gene mutated in AT, ATM, encodes a putative lipid or protein kinase. Most of the human AT patient phenotypes are recapitulated in Atm-deficient mice. Cells derived from Atm-/- mice, like those from AT patients, exhibit abnormal response to ionizing radiation. One of the known responses to ionizing radiation is the activation of a nuclear tyrosine kinase encoded by the c-abl proto-oncogene. Ionizing radiation does not activate c-Abl in cells from AT patients or in thymocytes or fibroblasts from the Atm-deficient mice. Ectopic expression of a functional ATM kinase domain corrects this defect, as it phosphorylates the c-Abl tyrosine kinase in vitro at Ser 465, leading to the activation of c-Abl. A mutant c-Abl with Ser 465 changed to Ala 465 is not activated by ionizing radiation or ATM kinase in vivo. These findings identify the c-Abl tyrosine kinase as a downstream target of phosphorylation and activation by the ATM kinase in the cellular response to ionizing radiation.

No association between Novelty Seeking and dopamine D4 receptor (D4DR) exon III seven repeat alleles in Baltimore Longitudinal Study of Aging participants

Abstract: Recent studies by Ebstein et al and Benjamin et al found associations between long repeat polymorphisms in the D4 dopamine receptor gene (D4DR) and individual variation in a human personality trait, identified as 'Novelty Seeking' (NS). Ebstein et al used the Tridimensional Personality Questionnaire (TPQ) to measure NS scores; Benjamin et al used the Revised NEO Personality Inventory (NEO-PI-R) to estimate NS scores. However, Malhotra et al failed to replicate the association between the direct measure of NS using the TPQ and the long alleles of the D4DR genotypes in two Finnish samples. In an attempt to confirm the association found by Benjamin et al using NEO-PI-R estimated NS, the present study used an alternative design extreme groups strategy to select high and low novelty seeking research volunteers from the Baltimore Longitudinal Study of Aging (BLSA). There were no significant associations between long alleles (7-repeat allele) and high novelty seeking groups. The findings of Ebstein and colleagues and those of Benjamin and colleagues do not generalize to this American middle-aged, mixed-gender sample, a conclusion also consistent with the findings of a recent Swedish study. Demographic factors such as the age and gender composition of the samples are important sources of variation in allelic association studies and future research must carefully address whether the D4DR genetic polymorphisms vary substantially across demographic groups.

[Cytotoxicity and genotoxicity of methyl tert-butyl ether and its metabolite to human leukemia cells].

Abstract: DNA damage of human leukemia (HL-60) cells caused by methyl tert-butyl ether (MTBE), a new gasoline additive, and its metabolites tert-butyl alcohol (TBA), a-hydroxyisobutyric acid (HIBA) and formaldehyde was determined by single cell gel electrophoresis (SCGE), with release of lactate dehydrogenase as an indicator for evaluating its cytotoxicity. Results showed that MTBE, TBA and HUBA at levels of 1 to 30 mmol/L could cause DNA damage in a dose-dependent pattern. Formaldehyde at level of 5 mumol/L could cause DNA damage, but at a higher level could decrease DNA migration. It suggested that MTBE and its metabolites could have genotoxicity, however, with doses causing genotoxic effects, no cytotoxic effect by MTBE, TBA and HIBA was observed, but formaldehyde presented obvious cytotoxic effect.

Clinical studies on pulpitis and periapical periodontitis caused by traumatic occlusion

Abstract: 89 cases including 100 teeth with pulpitis and apical periodontitis caused by traumatic occlusion were clinically observed. All teeth are caries-free, no any dental disease, and no pocket formation. But there is a distinct evidence of marked occlusal trauma, such as premature contact and occlusal interference. The single-root teeth are usually involved. When subjected to vitality testing the teeth associated with the periapical lesions sometimes yield positive response (about 30%). The result of investigation endodontic treatment demonstrated that the presence of predisposing factors of trauma from occlusion led to decrease of endodontic success.

The effect of artificial traumatic occlusion on the pulp and periodontium in rat molars

Abstract: In order to study relationship between the period of occlusal trauma and pulpal and periodontal tissues, 44 rats were used in experimental occlusal trauma. The pulpal and periodontal tissues of rat molars were observed by histological examination and micrographic examination. The results showed that the damage of pulp became more serious as time went on, but periodontium appeared adaptive changes. The same changing area in periodontal tissues were observed between histological section and micrographic film. The results provide experimental evidences for the pathology and pathogeny of pulpitis and perioapical periodontitis caused by occlusal trauma.

[A three-year clinical evaluation of five light-cured composite resins in fillings of posterior teeth].

Abstract: In order to study the clinical performance and the evaluation method of light-cured composite resin in filling for posterior teeth, two evaluation methods were used to evaluate 5 light-cured posterior composite resin fillings in 169 adult posterior class I cavity. Results showed that each evaluation method has its own advantages. The curative effect was declined with time in this study. Failures and defects were mainly occurred after 3 years. Secondary caries, loss of fillings and marginal stainings were the main reasons of failures. Compared with the effect of 1 year, the success rate after 3 years declined significantly, and further long-term clinical observation is needed.

Preliminary study on oncogene MDM2 in acute leukemias

Abstract: OBJECTIVE To explore the causes of MDM2 gene overexpression. METHODS The amplification and overexpression of MDM2 gene in 41 acute leukemia patients and two leukemic cell lines (K051 and HL60) were studied by using Southern blot, dot hybridyzation and RT-PCR techniques. RESULTS Overexpression of MDM2 gene was found in 51.2% (21/41) of the patients and HL60 cell line, but no amplification of the gene was found in all the patients and the two cell lines. CONCLUSION The level of MDM2 gene expression was related to the prognoses of the patients but not to FAB subtypes of acute leukemias.

Epidemiological characteristics and risk factors of hepatitis E in Taiyuan

Abstract: We investigated epidemiologically the risk factors of hepatitis E in Taiyuan. Of 385 patients with acute viral hepatitis collected, 191 (49.61%) were serologically identified to have hepatitis A, 104(27.01%) HB, 34 (8.80%) HE, 20 (5.19%) HC and 22 (5.72%) unidentified types. The male to female ratio of HE as 6.5 : 1. The median age of occurrence in the patients with HE was 38.5 years. One of three pregnant women with HE developed premature labor with fetal wastage. Case-control study was conducted in 70 patients with HE and 70 controls. The controls were selected from other subjects with no histories of hepatitis and matched by age and sex. The data were dealed with single factor analysis and conditional logistic regression analysis. The results showed that eating meals in resturants (OR 2.01, 95% CL 1.28-3.15), contacting with hepatitis case (OR 6.04, 95% CL 1.24-29.29), ingesting dirty drink (OR 2.16, 95% CL 2.05-2.26) are the major risk factors for HE.