Biomedical subjects

S Wei

Publications and source records attributed to S Wei.

At least 91 records · Page 5Linked to original sources

PubMed1999

Cell culture of sporadic hepatitis E virus in China.

The isolation and identification of the 87A strain of epidemic hepatitis E virus (HEV) by means of cell culturing have been described previously. This paper reports the successful isolation of a sporadic HEV strain (G93-2) in human lung carcinoma cell (A549) cultures. The etiology, molecular and biological properties, and serological relationship of this new strain to other, epidemic HEV strains are described. The propagation of both sporadic and epidemic HEV strains in a cell culture system will facilitate vaccine research.

Acids↗

PubMed1999

Probiotics inhibit enteropathogenic E. coli adherence in vitro by inducing intestinal mucin gene expression.

Probiotic agents, live microorganisms with beneficial effects for the host, may offer an alternative to conventional antimicrobials in the treatment and prevention of enteric infections. The probiotic agents Lactobacillus plantarum 299v and Lactobacillus rhamnosus GG quantitatively inhibited the adherence of an attaching and effacing pathogenic Escherichia coli to HT-29 intestinal epithelial cells but did not inhibit adherence to nonintestinal HEp-2 cells. HT-29 cells were grown under conditions that induced high levels of either MUC2 or MUC3 mRNA, but HEp-2 cells expressed only minimal levels of MUC2 and no MUC3 mRNA. Media enriched for MUC2 and MUC3 mucin were added exogenously to binding assays and were shown to be capable of inhibiting enteropathogen adherence to HEp-2 cells. Incubation of L. plantarum 299v with HT-29 cells increased MUC2 and MUC3 mRNA expression levels. From these in vitro studies, we propose the hypothesis that the ability of probiotic agents to inhibit adherence of attaching and effacing organisms to intestinal epithelial cells is mediated through their ability to increase expression of MUC2 and MUC3 intestinal mucins.

Bacterial Adhesion↗

PubMed1999

Identification of a locus for susceptibility to renal cell carcinoma in the Long-Evans Cinnamon rat.

The Long-Evans Cinnamon (LEC) mutant rat shows higher incidence of renal cell carcinomas induced by a treatment with the chemical carcinogen N-diethylnitrosamine, as compared to the normal control rat. We performed the first genome-wide scan for genes responsible for susceptibility to chemically induced renal cell carcinoma in an F2 intercross obtained by mating the LEC and Fischer-344 (F344) rats. The genotype of 71 (F344 x LEC) F2 progenies was determined with the use of 338 simple sequence length polymorphisms (SSLPs) spread over the genome. The F2 rats which carried renal cell carcinoma were shown to possess the incidence of homozygosity of the LEC allele which is higher than that of the other genotypes at SSLP markers on chromosome 5 (chi2 = 17.5 for D5Rat21). Our linkage analysis has led to the revelation of a novel gene that influences susceptibility to renal cell carcinoma on rat chromosome 5.

Alkylating Agents↗

PubMed1999

An efficient multiplex PCR suitable for large scale typing in linkage mapping.

The dissection of polygenic traits is made possible with the development of microsatellite markers. Linkage study of this kind involves many markers with tens of hundreds of samples. Although typing essentially contains only two steps: PCR amplification and gel electrophoresis. Such work is still heavy when a large number of samples had to be genotyped. Multiplex PCR may reduce the work, but one has to optimize the conditions from marker to marker. Here we describe a dye-compatible multiplex PCR that works under standardized condition without the need to pre-determine the combinational primer concentration and the time-consuming step to mix many samples with gel loading dye before electrophoresis. This successful protocol should greatly reduce the cost and labor for genetic study of polygenic traits.

Animals↗

PubMed1999

Retinoblastoma protein expression leads to reduced Oct-1 DNA binding activity and enhances interleukin-8 expression.

Tumor cell lines with a defective retinoblastoma gene are unable to transcribe the HLA class II genes in response to IFN-gamma treatment, and reconstitution of functional Rb rescues IFN-gamma-induced class II gene expression. However, the molecular mechanism of Rb rescue of the class II genes is unknown. We have examined the effect of Rb expression on the activation of the promoter for HLA-DRA, the prototype class II gene. Oct-1, a POU domain transcription factor, was identified as a repressor of HLA-DRA promoter activity in the Rb-defective cells. Rb expression led to phosphorylation of Oct-1, thus relieving its repressive effect. Oct-1 has also been shown to repress interleukin 8 promoter activity. Consistent with reduced levels of Oct-1 DNA binding activity in the Rb-transformed cell lines, interleukin 8 expression is higher in these cell lines.

Blotting, Western↗

PubMed1999

Early intervention promotes intellectual development of premature infants: a preliminary report. Early Intervention of Premature Infants Cooperative Research Group.

OBJECTIVE: To evaluate the effect of early intervention on the intellectual development of the premature infants. METHODS: Premature infants at gestational age of 28-36.9 weeks were randomly divided into two groups: intervention and conventional care groups. Normal newborn infants during the same period were included in the control group (routine care). Up to March 1996, 156 cases were over the age 1.5-2 years (corrected age), 52 in the intervention group, 51 in the conventional care group and 53 in the normal control group. Parents were taught to carry out the 0-2 year intervention program, which included motor, cognitive, speech development and social behavior. Every three months, height, weight and head circumference were measured. At the age of one and a half and two years, all infants in the three groups received infant development tests of Child Development Center of China (CDCC) scale. The examiner did not know which infant had received intervention. RESULTS: There was no significant difference in biological factors among the two premature groups and in cultural and social factors among the three groups. Intelligence tests at the age of one and a half and two years showed that the average mental development index (MDI) in the intervention group was 13.8 and 14.6 higher than those in the conventional care group and the differences were significant. The psychomotor development index (PDI) was 5.2 and 4.7 higher but the differences were not significant. The MDI and PDI in the intervention group and normal control were quite close, but at two years, the MDI and PDI in the intervention group were 5.7 and 7.3 higher than those in the normal control and the differences were significant (P < 0.05). Compared with the normal control, the MDI in conventional care group at one and a half and two years of age were 11.5 and 8.9 lower. The difference was very significant. There were four cases of mental retardation, whose mental development index (MDI) was less then 70 in the conventional care group, but none in the intervention group. CONCLUSIONS: Early intervention can promote intellectual development of the premature infants and may be beneficial to the prevention of mental retardation. Early and intensive intervention can produce better results. Bringing parent's initiative into full play through deepening their understanding of the importance of early intervention is the key to success.

Child Development↗

PubMed1999

[Determination of cortisol in plasma and 24-hour urine of patients with central serous chorioretinopathy].

OBJECTIVE: To study the cortisol levels in patients with central serous chorioretinopathy (CSCR). METHODS: Endogenous cortisol levels in plasma and urine were determined in 44 patients with CSCR by radioimmunoassay and chromatography, and their results were compared with that of 41 controls. RESULTS: In acute CSCR, the mean values of the plasma cortisol (296.53 +/- 77.03) ng/ml and 24-hour urine 17-hydroxysteroids (the major metabolite of cortisol metabolism) (12.08 +/- 4.82) mg/24 h revealed significantly higher values in the patient group (P < 0.05). CONCLUSIONS: Increased levels of endogenous cortisol play a role in the development of CSCR.

17-Hydroxycorticosteroids↗

PubMed1999

[Wavelength selection in management of central serous chorioretinopathy].

OBJECTIVE: To compare the effects of three kinds of laser wavelength in management of central serous chorioretinopathy (CSCR). METHOD: 89 patients with CSCR were randomly divided into three groups according to different wavelengths used. Visual acuity, fundus, fundus fluorescein angiography (FFA), light sensitivity, central visual field were performed before and after laser therapy. RESULT: Compared with red and green wavelength groups, in yellow group the visual acuity, light sensitivity were improved more significantly (P < 0.05), and the disease course was shortened, the effects in recurrence rate were similar in the three wavelength groups. CONCLUSION: In the three kinds of waves, yellow and red have similar and positive effects in the treatment of CSCR.

Adult↗

PubMed1999

[A pair-matched comparison and follow-up study of patients with euthytroid Graves ophthalmopathy and patients with hyperthyroid graves ophthalmopathy].

This study was intended to acquire a knowledge about the similarity and difference between euthyriod Graves ophthalmopathy (EGO) and hyperthyroid Graves ophthalmopathy (HGO), and about the outcome of the EGO cases. Twenty-seven EGO patients were pair-matched with 27 HGO patients, and 18 of the EGO patients were followed up for 1-6 years. The results showed that the EGO group had markedly more patients with diplopia, failure to close lids, limitation of eyeball movements, cornea involvement, and more patients with a difference of two eyes' exophthalmos degrees > or = 2 mm, but the HGO group had more patients with optic nerve involvement. No significant difference was found between the two groups' ophthalmopathic indexes by using the t-test. Drug therapy of the EGO group was more efficacious than that of the HGO group. The results of follow-up study showed that 61% of the EGO cases had hyperthyroidism and goiter within 5 months to 3 years, but 39% of the cases had no hyperthyroidism up to 6 years. These data suggest that EGO is associated with thyroid diseases and it can stand "alone" as an auto-immune disease.

Adolescent↗

PubMed1999

[Internal fixation for zygomatic arch fracture with super-high molecular weight poly D, L-lactic acid mini-plates and screws: a study in dogs].

OBJECTIVE: To investigate the internal fixation effects of super high molecular weight (Mv = 6.0 x 10(5) kD) poly D, L-lactic acid(PDLLA) mini-plates and screws. METHODS: 10 dogs were utilized in this experiment with the self-contrast study method, comparing with the titanium mini-plates and screws. RESULTS: The mechanical properties of the PDLLA mini-plates and screws appeared to be sufficient to enable undisturbed healing of depressed zygomatic arch fracture. CONCLUSION: The good fixation effect of PDLLA mini-plates and screws was as same as that of the titanium mini-plates and screws without the need of secondary operation.

Animals↗

PubMed1999

[Tissue reaction and degradation of super-high molecular weight poly D, L-lactic acid mini-plates and screws: an animal experiment].

OBJECTIVE: To investigate the tissue reaction and degradation processes of the super-high molecular weight(Mv = 6.0 x 10(5) kD) poly D, L-lactic acid(PDLLA) mini-plates and screws through the internal fixation for zygomatic arch fracture. METHODS: It was carried out by the self-contrast study method and comparing with the titanium mini-plates and screws. RESULTS: There was no side-effects on bone healing. The reaction of soft and hard tissues to PDLLA mini-plates and screws was similar to that of the titanium mini-plates and screws. No complication had been seen with the use of PDLLA mini-plates and screws, including infection, foreign body reaction and underlying osteolysis. The PDLLA devices had no changes in shape after 3 months, and then became the grains in different sizes after 6 months, and were completely resorbed within 12 months in vivo. CONCLUSION: The super-high molecular weight PDLLA mini-plates and screws has good biocompatibility and proper degradation time. It is safe and effective to use the mini-plates and screws made of the super-high molecular weight PDLLA for internal fixation of bone.

Animals↗

PubMed1998

Early onset photoreceptor abnormalities induced by targeted disruption of the interphotoreceptor retinoid-binding protein gene.

Vision in all vertebrates is dependent on an exchange of retinoids between the retinal pigment epithelium and the visual photoreceptors. It has been proposed that the interphotoreceptor retinoid-binding protein (IRBP) is essential for this intercellular exchange, and that it serves to prevent the potentially cytotoxic effects of retinoids. Although its precise function in vivo has yet to be defined, the early expression of IRBP suggests that it may also be required for normal photoreceptor development. To further assess the biological role of IRBP, we generated transgenic mice with targeted disruption of the IRBP gene (IRBP-/- mice). Specifically, homologous recombination was used to replace the first exon and promoter region of the IRBP gene with a phosphoglycerate kinase-promoted neomycin-resistant gene. Immunocytochemical and Western blot analyses demonstrated the absence of IRBP expression in the IRBP-/- mice. As early as postnatal day 11, histological examination of the retinas of IRBP-/- mice revealed a loss of photoreceptor nuclei and changes in the structural integrity of the receptor outer segments. At 30 d of age, the photoreceptor abnormalities in IRBP-/- mice were more severe, and electroretinographic recordings revealed a marked loss in photic sensitivity. In contrast, no morphological or electrophysiological changes were detected in age-matched heterozygotes. These observations indicate that normal photoreceptor development and function are highly dependent on the early expression of IRBP, and that in the absence of IRBP there is a slowly progressive degeneration of retinal photoreceptors.

Aging↗

PubMed1998

Control of lytic function by mitogen-activated protein kinase/extracellular regulatory kinase 2 (ERK2) in a human natural killer cell line: identification of perforin and granzyme B mobilization by functional ERK2.

The signal pathways that control effector function in human natural killer (NK) cells are little known. In this study, we have identified the critical role of the mitogen-activated protein kinase (MAPK) pathway in NK lysis of tumor cells, and this pathway may involve the mobilization of granule components in NK cells upon interaction with sensitive tumor target cells. Evidence was provided by biological, biochemical, and gene transfection methods. NK cell binding to tumor cells for 5 min was sufficient to maximally activate MAPK/extracellular signal-regulatory kinase 2 (ERK2), demonstrated by its tyrosine phosphorylation and by its ability to function as an efficient kinase for myelin basic protein. MAPK activation was achieved in NK cells only after contact with NK-sensitive but not NK-resistant target cells. In immunocytochemical studies, cytoplasmic perforin and granzyme B were both maximally redirected towards the tumor contact zone within 5 min of NK cell contact with tumor cells. A specific MAPK pathway inhibitor, PD098059, could block not only MAPK activation but also redistribution of perforin/granzyme B in NK cells, which occur upon target ligation. PD098059 also interfered with NK lysis of tumor cells in a 5-h 51Cr-release assay, but had no ability to block NK cell proliferation. Transient transfection studies with wild-type and dominant-negative MAPK/ERK2 genes confirmed the importance of MAPK in NK cell lysis. These results document a pivotal role of MAPK in NK effector function, possibly by its control of movement of lytic granules, and clearly define MAPK involvement in a functional pathway unlinked to cell growth or differentiation.

Calcium-Calmodulin-Dependent Protein Kinases↗

PubMed1998

A fragment of the yeast DNA repair protein Rad4 confers toxicity to E. coli and is required for its interaction with Rad7 protein.

The RAD4 gene of Saccharomyces cerevisiae is required for the incision of damaged DNA during nucleotide excision repair. Plasmids carrying the wild-type RAD4 gene cannot be propagated in Escherichia coli. In this study, a rad4 mutant that can be grown in E. coli was isolated. This rad4 allele is deleted of a large positively charged segment of the RAD4 coding region which is toxic to E. coli when expressed alone. The deletion mutant retains its ability to interact with Rad23 protein but not with Rad7 protein and is defective in nucleotide excision repair. The smallest Rad4 fragment that is toxic to E. coli consists of 336 amino acids with a calculated pI=9.99.

Alleles↗

PubMed1998

A keratinocyte-specific epoxygenase, CYP2B12, metabolizes arachidonic acid with unusual selectivity, producing a single major epoxyeicosatrienoic acid.

The CYP monooxygenase, CYP2B12, is the first identified skin-specific cytochrome P450 enzyme. It is characterized by high, constitutive expression in an extrahepatic tissue, the sebaceous glands of cutaneous tissues. It is expressed exclusively in a subset of differentiated keratinocytes called sebocytes, as demonstrated by Northern blot analysis, in situ hybridization, and polymerase chain reaction. The onset of its expression coincides with the morphological appearance of sebaceous glands in the neonatal rat. Recombinant CYP2B12 produced in Escherichia coli epoxidizes arachidonic acid to 11,12- and 8,9-epoxyeicosatrienoic acids (80 and 20% of total metabolites, respectively). The identification of arachidonic acid as a substrate for this skin-specific CYP monooxygenase suggests an endogenous function in keratinocytes in the generation of bioactive lipids and intracellular signaling.

8,11,14-Eicosatrienoic Acid↗

PubMed1998

Loss of cardiac magnesium in experimental heart failure prolongs and destabilizes repolarization in dogs.

OBJECTIVES: We sought to determine whether heart failure results in loss of cardiac magnesium sufficient to alter cellular electrophysiology. BACKGROUND: Free magnesium has numerous intracellular roles affecting metabolism, excitability and RNA synthesis. Total cardiac magnesium content is reduced in heart failure, but it is unclear whether magnesium loss is primary or iatrogenic. Furthermore, it is unknown whether free magnesium levels are affected or whether a change in free magnesium would alter cellular electrophysiology. METHODS: Eight mongrel dogs underwent demand ventricular pacing (VVI) at 250 beats/min for 3 weeks to induce heart failure. Sublingual epithelial magnesium was measured before pacing and at death. Left ventricular myocytes were isolated and loaded with Mag-Indo-1 to measure free magnesium ([Mg2+]i); myocytes from eight normal dogs served as controls. To test whether changes in [Mg2+]i in this range could alter cellular repolarization, current-clamped myocytes were dialyzed with 0.5 or 1.0 mmol/liter MgCl2. RESULTS: Mean sublingual epithelial magnesium fell significantly in the paced animals, from 36.9 +/- 0.5 to 33.9 +/- 0.7 mEq/liter (p < 0.01). Mean cardiac [Mg2+]i was significantly lower in the dogs with heart failure--0.49 +/- 0.06 versus 1.06 +/- 0.15 mmol/liter (p < 0.003). Time to 90% repolarization was significantly shorter in cells dialyzed with 1.0 mmol/liter compared with 0.5 mmol/liter MgCl2 in myocytes from normal dogs or dogs with heart failure (596 +/- 34 vs. 760 +/- 58 ms in normal dogs and 586 +/- 29 vs. 838 +/- 98 ms in dogs with heart failure; p < 0.05 for each). CONCLUSIONS: Experimental heart failure results in both tissue and cardiac magnesium loss in the absence of drug therapy. Free cardiac magnesium is significantly reduced, possibly contributing to abnormal repolarization in heart failure.

Action Potentials↗

PubMed1998

Single- and multiple-dose pharmacokinetic comparison of a sustained-release tablet and conventional tablets of naproxen in healthy volunteers.

The pharmacokinetics of a new sustained-release tablet of naproxen (500 mg once daily) were compared with a conventional tablet (250 mg twice daily) after single- or multiple-dose oral administration in healthy volunteers using an open, randomized two-way crossover experimental design. Naproxen was well absorbed from the sustained-release tablet (approximately 97%) compared with the conventional tablet. Pharmacokinetic data showed that the sustained-release formulation reached significantly delayed mean peak plasma levels (Cmax) in both single- and multiple-dose studies and lower Cmax in a single-dose study than the conventional formulation. However, there were no statistically significant differences in other pharmacokinetic parameters, including area under the concentration-time curve (AUC), elimination half-life (t1/2), and elimination rate constant (Ke), in either single- or multiple-dose studies between the two treatments. In addition, there were no significant differences between formulations in Cmax, minimum plasma concentration (Cmin), and fluctuation index in the multiple-dose study.

Adult↗

PubMed1998

A major quantitative trait locus co-localizing with cholecystokinin type A receptor gene influences poor pancreatic proliferation in a spontaneously diabetogenic rat.

The Otsuka Long-Evans Tokushima Fatty (OLETF) rat is an animal model for obese-type, non-insulin-dependent diabetes mellitus (NIDDM) in humans. The OLETF rat has poor capacity for pancreatic proliferation, which may be the critical pathogenetic event in NIDDM development. Our investigation was designed to identify quantitative trait loci (QTLs) responsible for poor pancreatic proliferation by examining compensatory proliferation of the pancreatic remnant after partial pancreatectomy and performing a genome-wide scan in an F2 intercross obtained by mating the OLETF and the Fischer-344 (F344) rats. We identified a highly significant QTL on rat Chromosome 14 with a maximum lod score of 16.7, which accounts for 55% of the total variance. The QTL co-localizes with the gene encoding cholecystokinin type A receptor (CCKAR) which is likely to mediate the trophic effect of cholecystokinin on pancreas and is defective in the OLETF rat.

Animals↗