Search PubMed⌕ Search

Biomedical subjects

X Chen

Publications and source records attributed to X Chen.

At least 955 records · Page 53Linked to original sources
PubMed1998

Association of CYP2D microsatellite polymorphism with Lewy body variant of Alzheimer's disease.

OBJECTIVE: To examine the genetic association of CYP2D6 locus with Lewy body variant (LBV) and Parkinson's disease (PD). METHODS: Allelic association was studied in patients with pure AD, LBV, and PD by using the CYP2D microsatellite, the (dG-dT)n dinucleotide repeat (n=16 to 27) located between CYP2D8P and CYP2D7 genes, and the CYP2D6 B and D mutations. RESULTS: We found overrepresentation of the alleles longer than 21 repeat (the long-type alleles) in LBV (allele frequency, 0.313) (odds ratio=1.99, p=0.019 by chi2 test) and in PD (0.298) (odds ratio=1.86, p=0.037), but not in pure AD (0.196), compared with the age-matched control (0.186). Strong association was noted of the long-type alleles with the CYP2D6 B mutation (odds ratio=88.50, p < 0.001 by Fisher's exact test), but not with the D mutation or the deletion of CYP2D6 gene. CONCLUSIONS: The CYP2D locus is closely associated with LBV and PD. The CYP2D6 B mutation may be involved in pathogenesis of LBV and PD in a dominant-negative manner, or in the linkage disequilibrium of the CYP2D microsatellite to another pathogenic gene locus.

Aged↗
PubMed1998

Acute lowering of plasma fatty acids lowers basal insulin secretion in diabetic and nondiabetic subjects.

The objective of this study was to determine whether basal plasma free fatty acid (FFA) concentrations affect basal insulin secretion rates (ISRs). Effects of FFA levels on basal ISRs were evaluated by lowering basal plasma FFA levels with nicotinic acid (NA) (100-150 mg p.o., q 30 min x 4 h) in type 2 diabetic patients and in normal volunteers. Lowering of FFAs (from approximately 600 to approximately 100 micromol/l) lowered ISRs in type 2 diabetic patients during isoglycemic clamping (from 139 to 101 pmol/min; -23%; P < 0.02) and euglycemic clamping (from 99 to 63 pmol/min; -36%; P < 0.03) and in normal subjects during euglycemic clamping (from 127 to 96 pmol/min; -25%; P < 0.03). In addition, peripheral insulin concentrations decreased by approximately 30% in diabetic and nondiabetic subjects. NA had no direct effect on ISRs; that is, NA did not change ISRs when plasma FFAs were prevented from decreasing with a lipid/heparin infusion. We concluded that 1) basal plasma FFAs exerted physiologically important, long-lasting effects supporting 25-33% of basal insulin secretion in nondiabetic and diabetic subjects; 2) basal plasma FFAs were responsible for some of the hyperinsulinemia in normoglycemic obese subjects; and 3) NA had no direct effect on insulin secretion.

3-Hydroxybutyric Acid↗
PubMed1998

A novel approach to glioma gene therapy: down-regulation of the vascular endothelial growth factor in glioma cells using ribozymes.

Glioblastoma multiforme is one of the most highly vascularized solid neoplasms, therefore treatments that target neovascularization process would be of great clinical importance. Studies of glioblastoma angiogenesis have revealed that expression of the vascular endothelial growth factor (VEGF) is up-regulated in these tumors. Previous reports have shown that down-regulation of VEGF correlates with modification in the glioma growth. To examine this phenomenon further, in this study we constructed two hammerhead ribozymes (RZI and RZII) to target the 5' common region of VEGF mRNA. Both ribozymes exhibited site-specific cleavage to a 318-nucleotide VEGF transcript and showed a high digestion efficiency in vitro (65-95%). After the transfection of glioma cells with two expression vectors carrying the ribozyme sequence, Northern blot analyses detected high levels of ribozyme expression. Treatment of the glioma cells with the ribozymes resulted in a reduction in VEGF mRNA in six of eight clones. Furthermore, the anti-VEGF effect was confirmed at protein level. Thus, enzyme-linked immunoabsorbent analyses (ELISA) showed a >70% reduction in the VEGF165 expression level. These results indicate that hammerhead ribozymes may be useful in down-regulating VEGF expression and suggest that anti-VEGF strategies may be used to potentiate other gene therapies targeting tumor suppressor genes.

Blotting, Northern↗
PubMed1998

[Application of the time-series method to analyse the seasonal distribution of epidemic encephalitis B incidence in Guangdong province in the years of 1984-1993].

This paper analysed the data of epidemic encephalitis B incidence that was constituted to time- series and the two-ordered contingency table in Guangdong province from 1984 to 1993. Two different kinds of statistical methods of run- test and ordered-log-ratio test were applied to study the characteristics of seasonal distribution. Consistent conclusion was obtained to show that there appeared an obvious seasonal cyclic characteristic of a peak every year (June or July) for the incidence of epidemic encephalitis B. It is helpful for the epidemiologists to understand the principle and method of these statistical tests.

China↗
PubMed1998

[Study of HDV infection in Shandong province].

To understand the situation of HDV infection in Shandong province and to explore the relationship between HDV and HBV infections, 2681 samples infected with HBV were tested for serum anti-HDV with enzyme linked immunosorbent assay, in Shandong. Among them, 207 (7.72%) were found to be anti-HDV positive. Anti-HDV positive rates in HBsAg carriers and in hepatitis B patients were 3.16% and 13.15%, respectively. A significant difference (P < 0.001) was noticed between the two groups. In the second group, anti-HDV positive rates in patients with chronic active hepatitis and severe hepatitis were both higher than those in patients with acute hepatitis and chronic persistent hepatitis and the difference was significant (P < 0.001). The longer the history and the more severe the condition the higher of the anti-HDV positive rate was seen. The results indicated that the combined and over-lapping HDV infections were both responsible for the chronic status of hepatitis B and its deterioration.

Adolescent↗
PubMed1998

Trinucleotide repeat expansion of spinocerebellar ataxia (SCA1) found in a Chinese family.

OBJECTIVE: To investigate the gene mutation and the ratio of the spinocerebellar ataxia type 1 (SCA1) in Chinese patients with autosomal dominant spinocerebellar ataxia (ADSCA). METHOD: The family material and DNA samples were collected from thirteen families with ADSCA. To determine the characteristics of the CAG trinucleotide repeats in SCA1 gene, the PCR products of the Rep1 and Rep2 primers were analyzed, and the bands with CAG repeat expansion were cloned by PCR2. 1 vector and sequenced. RESULTS: One family was found to have an expanded CAG repeat in the 13 families with ADSCA. The clinically affected individual was heterozygous with one disease allele being 55 CAG repeats, whereas the mean size of the CAG repeats on 104 chromosomes generated from unrelated control Chinese individuals is 29.3 (ranging from 18 to 34). CONCLUSIONS: The frequency of the SCA1 mutation is about 7% in the 13 Chinese families with ADSCA, suggesting that this type of genetic defect is not the main cause involved in the pathogenesis of ADSCA in China. Since the mutation has also been found in Caucasian, Japanese, Malaysian, and Bangladeshi kindreds, it is suggested that this genetic defect may well have multiple origins in different ethnic groups.

Adult↗
PubMed1998

[Applied anatomy of the pedicled patella transposition for repair of the superior articular surface of the medial tibial condyle].

To investigate the feasibility of using the pedicled patella for repaire of the superior articular surface of the medial tibial condyle, 37 lower limbs were studied by perfusion. In this series, there were 34 obsolete specimens and 3 fresh specimens of lower legs. Firstly, the vessels which supply to patella were observed by the methods of anatomy, section and casting mould. Then, the form and area of the patellar and tibial medial conylar articular surface were measured in 30 cases. The results showed: (1) the arteries supplied to patella formed a prepatellar arterial ring around patella, and the ring gave branches to patella; (2) medial inferior genicular artery and inferior patellar branches of the descending genicular arterial articular branch merge and acceed++ to prepatellar ring at inferior medial part of patella; (3) the articular surface of patella is similar to the superior articular surface of the tibial medial condyle on shape and area. It was concluded that the pedicled patella can be transposed to medial tibial condyle for repaire of the defect of the superior articular surface. The function of the knee can be reserved by this method.

Adult↗
PubMed1998

A study on visual evoked potential to show the relationship between the eyes and the twelve regular channels.

The visual electrophysiologic method was used to investigate the relationship between the eyes and the 12 regular channels. The values of the latent period and the amplitude of P100 wave were calculated and compared statistically. The results show that: 1) The eyes and the 12 regular channels are closely related, no matter whether the channels are classically associated with the eyes or not, while the control (non-channel)/ point has no such relationship; 2) the degrees of relationship between the eyes and the 12 regular channels vary significantly; and 3) acupuncture at the 12 regular channels induces different effects on the visual evoked potential that the Urinary Bladder Channel presents a facilitation effect whereas all the other channels chiefly show an inhibitory effect.

Adolescent↗
PubMed1998

[Correction of square face].

OBJECTIVE: This work was to provide an advanced operation method for square face correction. METHODS: The method is characterized by resecting hyperostosis of the mandibular angle, the bulky masseter and the buccal fat pad through intraoral or combined extra-intraoral approach. RESULTS: Good results were obtained in 10 cases after follow-up of 4 to 28 months. CONCLUSION: This operative method proved to be quite ideal and applicable to treat square face.

Adult↗
PubMed1998

[An analysis of bacterial resistance to antimicrobial agents in a burn centre].

OBJECTIVE: To investigate bacterial resistance to antimicrobial agents in the background of extensive employment of third-generation cephalosporins in the treatment of burn infection. METHODS: Bacterial susceptibility testing was carried out using Kirby-Bauer method. RESULTS: Out of 259 Gram negative bacilli isolates, 31% of these strains were all resistant to cefotaxime, ceftriaxone, cefoperazone and ceftazidime. In vitro test, susceptibility of 52% third-generation cephlosporins resistant strains were restored by cefoperazone/sulbactum. 23.8% of P. aeruginosa were resistant to imipenem, 51.2% to ciprofloxacin. 28.6% of A. anitratum were resistant to imipenem, 21.4% to ciprofloxacin. 9.9% of enterobacteriaceae were resistant to imipenem, 20.4% to ciprofloxacin. 26.9% of MRSA were resistant to imipenem, 73% to ciprofloxacin. No norvancomycin resistance was detected. 2.7% of E. faecalis were resistant to norvancomycin. CONCLUSION: It is likely that the observed resistance to third-generation cephalosporins may be partially due to chromosome-mediated type-1 beta- lactamase.

Burns↗
PubMed1998

[Study on dopamine metabolite in cerebrospinal fluid of schizophrenics and epilepsics].

The concentration of dopamine (DA) metabolite-homovanillic acid (HVA) in cerebrospinal fluid (CSF) of 40 patients with schizophrenia 27 with epilepsy and 15 controls without disorders of CNS was reported. The results showed that there were no significant differences in mean levels of HVA among the three groups. It is suggested that both schizophrenia and epilepsy are not abnormal in total level of DA metabolism.

Adult↗
PubMed1998

[The expression of glutathione S-transferase pi in human ovarian cancer as an indicator of resistance to chemotherapy].

OBJECTIVE: To study the relationship between the expression of glutathione S-transferase pi (GST-pi) in cancer tissue and the chemoresistance in patients with ovarian carcinoma. METHODS: The expression of GST-pi in 53 cases of ovarian cancer, 20 ovarian benign tumors and 17 normal controls was determined by using immunohistochemical SP method and the results were studied in correlation with some clinical and pathological data. RESULTS: (1) Positive expression with GST-pi was demonstrated in 60.4% of malignant and 10.0% of benign ovarian tumors while the expression was negative in normal controls. (2) No significant difference for the expressions was shown in relation to the histopathology, the clinical staging and the size of residual tumors after cytoreductive surgery. (3) The positive rate of the expression was 47.2% (17/36) for the initially treated patients while those with tumor recurrence had a positive rate of 88.2% (15/17). (4) GST-pi positive cases showed less response rate of 37.5% (12/32) to chemotherapy as compared with that of 76.2%(16/21) for GST-pi negative cases. (5) The survival period of the patients with GST-pi positive expression was shorter than that of those with GST-pi negative expression. CONCLUSION: The expression of GST-pi in patients with ovarian carcinoma in closely related to the chemosensitivities clinically. Determinations of the GST-pi are useful for predicting the chemosensitivities and the prognosis of the disease.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1998

[Alterations of amino acids in rat cerebral cortex of infectious brain injuries].

Concentrations of amino acids such as glutamate(Glu), glutamine(Gln), gamma-aminobutyric (GABA), glycerin(Gly) in rat cerebral cortex were measured by o-phthaldialdehyde method to clarify alterations of these amino acids in infectious brain injuries(IBI). The results were that Gln and GABA in groups treated by bordetella pertussis suspension(BP) 4h were increased compared to those in the group treated by the normal saline(NS) or the operative control(OC) and a positive correlation with water content or Evans blue content, respectively. In the 24h BP group, Gln was still increased; GABA and Gly were decreased compared to those in the NS or OC group. The findings suggest that GLu, Gln, and Gly play an important role and GABA may be a marker of injury in pathogenetic mechanism of IBI induced by BP.

Animals↗
PubMed1998

[Association of apoB levels and nutrition of coronary heart disease patients].

Blood lipids and apo B levels were measured on 101 Coronary Heart Disease patients and 100 controls. The results showed that the apo B levels of patients were higher than that of controls. The average values were (877 +/- 129) mg/L and (800 +/- 95) mg/L respectively. It was found that there was close association among body mass index(BMI), ratio of waist circumference to hip circumference(WHR) and apo B levels. Besides, the results showed that dietary habit of "eating fat meat" might result in the increase of apo B concentration while the VC intake was negatively associated with serum apo B levels.

Adult↗
PubMed1998

[Study on telomeric association in nasopharyngeal carcinoma].

The chromosomal telomeric association in peripheral blood lymphocytes from 25 untreated patients with nasopharyngeal carcinoma (NPC) and in NPC cell lines (CNE) was investigated by using chromosome G banding technique. The cell telomeric association rate of patients (35.07%) was found to be higher than that of controls(20.27%) (P < 0.01), while in the two groups the distributions of chromosomes involved were approximately the same (P > 0.05). The telomeric association rates of patients were significantly higher than those of control in chromosomes 1, 2, 3, 4, 7, 11, 15, and 17(P < 0.05). In NPC lines (CNE), 94% of the cell division phases showed telomeric association. Chromosomes 2, 3, 5, 11 and 16 had higher frequencies of association than other chromosomes. The most frequent telomeric association was single chromatid association.

Adult↗
PubMed1998

[Study on the joint action of selenium and cadmium on DNA damage of rat liver cells].

The effect of joint action of selenium and cadmium on DNA damage in rat liver cells was investigated with single cell gel electrophoresis. The results show that both selenium and cadmium can induce DNA damage at the concentration of 8.75 mumol/L, 17.5 mumol/L and 35 mumol/L. The degree of DNA damage induced by cadmium is more serious than by selenium. When selenium and cadmium act jointly, they can antagonize each other on DNA damage at the concentration of 8.75 mumol/L and 17.5 mumol/L, but not at the concentration of 35 mumol/L. There is an antagonism between selenium and cadmium on DNA damage in rat liver cells at certain concentrations.

Animals↗
PubMed1998

[Effect of crystalling temperatures on microstructure of dental glass-ceramic].

To know well the effect of crystalling temperature on the microstructure of dental glass-ceramic, the parameters of microstructure such as the type of crystal, crystal percentage, crystal size and crystal form were investigated by altering crystalling temperatures and using scanning electronic microscope, energy dispersive X-ray analysis and X-ray diffraction techniques. The results showed that the crystalline phase was identified to be tetrasilicic fluromica, and the promotion of crystalling temperature contributed to the increased crystal percentage, crystal size and the transformation of crystal form from 830 degrees C to 950 degrees C.

Crystallization↗