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L Wei

Publications and source records attributed to L Wei.

At least 91 records · Page 5Linked to original sources
PubMed2000

Differences in vulnerability to permanent focal cerebral ischemia among 3 common mouse strains.

BACKGROUND AND PURPOSE: Genetically engineered mice are used to study the role of single genes in cerebral ischemia, but inherent, strain-dependent differences in neuronal vulnerability may affect experimental end points. To examine this possibility, tissue injury resulting from focal ischemia and its relationship to cerebral hemodynamics were determined in 3 common mutant mouse strains. METHODS: Permanent middle cerebral artery ligation was performed in male C57BL/6J, Balb/C, and 129X1/SvJ mice. Mean arterial blood pressure, blood gases, basal and postischemic cortical blood flow ([(14)C]iodoantipyrine autoradiography and laser-Doppler flowmetry), posterior communicating artery patency, and infarct size were determined. RESULTS: Basal cortical blood flow did not differ among strains. Ten minutes after middle cerebral artery ligation, relative red cell flow in the ischemic cortex was 6% to 7% of preischemic flow in every strain. Despite similar hemodynamics, cortical infarcts in Balb/C mice were 3-fold larger than those in 129X1/SvJ and C57BL/6J mice; infarct size in the latter 2 strains was not significantly different. The posterior communicating artery was either poorly developed or absent in >90% of the Balb/C and C57BL/6J but in <50% of the 129X1/SvJ mice. CONCLUSIONS: The extent of ischemic injury differed markedly between the 3 strains. The presence and patency of posterior communicating arteries, although variable among strains, did not affect preischemic or postischemic cortical blood flow or bear any relationship to ischemic injury. Therefore, intrinsic factors, other than hemodynamic variability, may contribute to the differences in ischemic vulnerability among strains. These findings underscore the importance of selecting genetically matched wild-type controls.

Animals↗
PubMed2000

Physiological hyperinsulinemia stimulates p70(S6k) phosphorylation in human skeletal muscle.

Using tracer methods, insulin stimulates muscle protein synthesis in vitro, an effect not seen in vivo with physiological insulin concentrations in adult animals or humans. To examine the action of physiological hyperinsulinemia on protein synthesis using a tracer-independent method in vivo and identify possible explanations for this discrepancy, we measured the phosphorylation of ribosomal protein S6 kinase (P70(S6k)) and eIF4E-binding protein (eIF4E-BP1), two key proteins that regulate messenger ribonucleic acid translation and protein synthesis. Postabsorptive healthy adults received either a 2-h insulin infusion (1 mU/min.kg; euglycemic insulin clamp; n = 6) or a 2-h saline infusion (n = 5). Vastus lateralis muscle was biopsied at baseline and at the end of the infusion period. Phosphorylation of P70(S6k) and eIF4E-BP1 was quantified on Western blots after SDS-PAGE. Physiological increments in plasma insulin (42 +/- 13 to 366 +/- 36 pmol/L; P: = 0.0002) significantly increased p70(S6k) (P: < 0.01), but did not affect eIF4E-BP1 phosphorylation in muscle. Plasma insulin declined slightly during saline infusion (P: = 0.04), and there was no change in the phosphorylation of either p70(S6k) or eIF4E-BP1. These findings indicate an important role of physiological hyperinsulinemia in the regulation of p70(S6k) in human muscle. This finding is consistent with a potential role for insulin in regulating the synthesis of that subset of proteins involved in ribosomal function. The failure to enhance the phosphorylation of eIF4E-BP1 may in part explain the lack of a stimulatory effect of physiological hyperinsulinemia on bulk protein synthesis in skeletal muscle in vivo.

Adult↗
PubMed2000

An introductory overview of the epidemiological study on the population at the high background radiation areas in Yangjiang, China.

The epidemiological study on the residents of the high background radiation areas in Yangjiang, China was started by Chinese scientists in 1972 and continued until 1986. In 1991, Japanese scientists recognized the importance of the work and a joint feasibility study was conducted with revised protocols. The feasibility study matured to a cooperative project involving both Chinese and Japanese scientists in 1992, which currently is still in progress. The project was divided into three phases; the first being from 1992 to 1995, the second from 1995-1998 and the third from 1998 to 2001. The results of the first phase were reported previously in 1996. The present paper is a historical overview of the studies before the cooperation and the first two phases. Remarks are made on the detailed data on dosimetry, cytogenetic studies and cancer epidemiology of a series of the papers in this supplemental issue. Some problems such as paradoxical observations between cytogenetic results and cancer mortality, and the importance of the high background study in risk assessment are discussed.

Background Radiation↗
PubMed2000

Measurements of Rn-222, Rn-220 and their decay products in the environmental air of the high background radiation areas in Yangjiang, China.

For the renewal of dose estimation from internal irradiation in the high background radiation areas (HBRA) of Yangjiang, the measurements of radon, thoron and their decay products in the environmental air were conducted, including: (1) integrating measurements of Rn-222 and Rn-220 concentrations; (2) eqilibrium factor F for Rn-222 and alpha-potential energy value of Rn-220; (3) external gamma radiation in places where radon measurements were undertaken; (4) cumulative exposure to indoor radon for each family in a case-control study on lung cancer. The Rn-Tn cup monitor method was used for the integrating measurement of Rn-222 and Rn-220 concentration. An alpha track detector was used for the integration measurement of Rn-222 concentration in the case-control study on lung cancer. The results of measurements show that although the investigated areas are located between the Equator and the Tropic of Cancer, and that people live in well-ventilated dwellings, the concentrations of radon, especially of Rn-220 are significantly higher in the indoor air of HBRA than those in the control area. The value of equilibrium factors for Rn-222, the alpha potential energy of decay products from Rn-222 and Rn-220 are determined.

Air↗
PubMed2000

Cancer mortality in the high background radiation areas of Yangjiang, China during the period between 1979 and 1995.

The objective of the present study was to estimate cancer risk associated with the low-level radiation exposure of an average annual effective dose of 6.4 mSv (including internal exposure) in the high background-radiation areas (HBRA) in Yangjiang, China. The mortality survey consisted of two steps, i.e., the follow-up of cohort members and the ascertainment of causes of death. The cohort members in HBRA were divided into three dose-groups on the basis of environmental dose-rates per year. The mortality experiences of those three dose groups were compared with those in the residents of control areas by means of relative risk (RR). During the period 1987-1995, we observed 926,226 person-years by following up 106,517 subjects in the cohort study, and accumulated 5,161 deaths, among which 557 were from cancers. We did not observe an increase in cancer mortality in HBRA (RR = 0.96, 96% CI, 0.80 to 1.15). The combined data for the period 1979-95 included 125,079 subjects and accumulated 1,698,316 person-years, observed 10,415 total deaths and 1,003 cancer deaths. The relative risk of all cancers for whole HBRA as compared with the control area was estimated to be 0.99 (95% CI, 0.87 to 1.14). The relative risks of cancers of the stomach, colon, liver, lung, bone, female breast and thyroid within whole HBRA were less than one, while the risks for leukemia, cancers of the nasopharynx, esophagus, rectum, pancreas, skin, cervix uteri, brain and central nervous system, and malignant lymphoma were larger than one. None of them were significantly different from RR = 1. Neither homogeneity tests nor trend tests revealed any statistically significant relationship between cancer risk and radiation dose. We did not find any increased cancer risk associated with the high levels of natural radiation in HBRA. On the contrary, the mortality of all cancers in HBRA was generally lower than that in the control area, but not statistically significant.

Adolescent↗
PubMed2000

Excess relative risk of solid cancer mortality after prolonged exposure to naturally occurring high background radiation in Yangjiang, China.

A study was made on cancer mortality in the high-background radiation areas of Yangjiang, China. Based on hamlet-specific environmental doses and sex- and age-specific occupancy factors, cumulative doses were calculated for each subject. In this article, we describe how the indirect estimation was made on individual dose and the methodology used to estimate radiation risk. Then, assuming a linear dose response relationship and using cancer mortality data for the period 1979-1995, we estimate the excess relative risk per Sievert for solid cancer to be -0.11 (95% CI, -0.67, 0.69). Also, we estimate the excess relative risks of four leading cancers in the study areas, i.e., cancers of the liver, nasopharynx, lung and stomach. In addition, we evaluate the effects of possible bias on our risk estimation.

Adolescent↗
PubMed2000

A case-control study of nasopharyngeal carcinoma in the high background radiation areas of Yangjiang, China.

The main purposes of this study were to identify the major determinants of nasopharyngeal carcinoma (NPC) in the high-background radiation areas (HBRA) in Yangjiang, China and to evaluate their potential confounding effects on the NPC risk associated with exposure to high background radiation. A matched case-control study was conducted using those who died of NPC during the period 1987-1995. Two controls were randomly selected for each case from those who died from causes other than malignancies and external causes. Cases and their controls were matched with respect to sex and the years of birth and death (+/- 5 years). Study subjects' next-of-kin were interviewed using a standardized questionnaire to collect information on socioeconomic status, dietary habits, tobacco smoking and alcohol consumption, disease history, pesticide use, medical X-ray exposure, the family history of NPC and so on. We succeeded in interviewing 97 cases and 192 controls. Univariate conditional logistic regression analysis showed that NPC risk was associated with the consumption of salted fish, homemade pickles, and fermented soy beans, education levels, the history of chronic rhinitis, and the family history of NPC. Multivariate conditional logistic regression analysis revealed that education levels (Odds ratio (OR) for middle school or higher levels vs. no school education = 3.8, 95% CI = 1.2 to 11.8), salted fish intake (OR = 3.2, 95% CI = 1.7 to 6.1), the history of chronic rhinitis (OR = 3.6, 95% CI = 1.3 to 10.1), and the family history of NPC (OR = 14.2, 95% CI = 2.7 to 73.4) were independent risk factors of NPC. Tobacco smoking (OR = 1.2, 95% CI = 0.7 to 2.1), and alcohol consumption (OR = 0.9, 95% CI = 0.5 to 1.9) were not significantly related to NPC risk. The ORs of NPC risk comparing HBRA and a nearby control area before and after adjustment for the major risk determinants identified in the present study were 0.86 (95% CI = 0.50 to 1.50) and 0.87 (95% CI = 0.45 to 1.67), respectively. Salted fish intake was a strong risk factor of NPC. Education, the history of chronic rhinitis and the family history of NPC were also related to NPC risk. The exposure to high background radiation in HBRA of Yangjiang was not related to NPC risk with or without the adjustment for those major risk determinants of NPC.

Adult↗
PubMed2000

Dose-effect relationship of dicentric and ring chromosomes in lymphocytes of individuals living in the high background radiation areas in China.

Chromosomes of 39 healthy family members (3 generations from 13 families) living both in the high-level background radiation areas (HBRA) and the control areas (CA) were studied. Cumulative dose from birth to the time of blood sampling was estimated by calculating measured exposure rate in each individual. The cumulative doses ranged 30.9-358.9 and 6.0-59.2 mGy for HBRA and CA, respectively. Peripheral lymphocyte chromosome preparations were made according to our improved method. Dicentric and ring chromosomes (Dic + Rc) were scored in average 2,527 cells per individual in HBRA and 2,694 cells in CA under a microscope equipped with an automated stage. A positive correlation between Dic + Rc and age was found in HBRA, while no such dose relationship was clear in CA. The frequency of Dic + Rc linearly increases over lifetime due to chronic low dose exposure and it is likely that the activation of repair enzymes is not triggered in the present HBRA. Threshold dose (rate) of the induction of chromosome aberrations, if any, is below the present dose (rate) level.

Adult↗
PubMed2000

Chromosome translocation in residents of the high background radiation areas in southern China.

We performed a cytogenetical study using chromosome painting analysis on 9 residents of the naturally high background radiation areas (HBRA) and 8 residents of the control areas in southern China. The estimated dose (air kerma) of each resident measured by an electric pocket dosimeter showed 2.20-4.23 mGy/year in HBRA and 0.56-0.70 mGy/year in the control areas. A total of 14,096 cells (1,566 cells/case) in the former and 17,522 cells (2,190 cells/case) in the latter were analyzed. Children, both in HBRA and in the control areas, had translocations at low frequencies. The frequency of translocations among elder individuals varied widely and it was not possible to detect dose effect although it was detected in dicentrics. The effect of radiation on the induction of chromosome aberrations, which have a statistically potential risk of causing malignant or congenital diseases, seems to be less significant than those of metabolic factors and/or mutagenic agents (excluding radiation) even in HBRA in China.

Aged↗
PubMed2000

Dose measurement, its distribution and individual external dose assessments of inhabitants in the high background radiation areas in China.

As a part of the China-Japan cooperative research on natural radiation epidemiology, we have carried out a dose-assessment study to evaluate the external exposure to natural radiation in the high background radiation areas (HBRA) of Yangjiang in Guangdong province and in the control areas (CA) of Enping prefecture since 1991. Because of the difficulties in measuring the individual doses of all inhabitants directly by personal dosimeters, an indirect method was applied in which the exposed individual doses were estimated from the environmental radiation doses measured by survey meters and the occupancy factors of each hamlet. We analyzed the dose in the hamlets and the variation in the occupancy factors to obtain the parameters of dose estimation on the inhabitants in selected hamlets; Madi and several hamlets of different dose levels in HBRA and Hampizai hamlet in CA. With these parameters, we estimated individual dose rates and compared them with those obtained from direct measurement using dosimeters carried by selected individuals. The results obtained are as follows. 1) The environmental radiation doses are influenced by the natural radioactive nuclide concentrations in building materials, the age of the building and the arrangement of the houses in a hamlet. There existed a fairly large and heterogeneous distribution of indoor and outdoor environmental radiations. The indoor radiation doses were due to exposure from the natural radioactive nuclides in the building materials and were about two times as large as the outdoor radiation doses. The difference between indoor and outdoor doses was not observed in CA. 2) The occupancy factor was influenced by the age of individuals and by the season of the year. The occupancy factor was higher for infants and aged individuals than for other age groups. This lead to higher dose rates of exposure to those age groups. 3) A good correlation was observed between the dose assessed indirectly and that measured directly and the correlation factor was 0.97.

Background Radiation↗
PubMed2000

Inhibition of volume-regulated and calcium-activated chloride channels by the antimalarial mefloquine.

We have used the whole-cell patch-clamp technique to study the effect of mefloquine (Lariam), a commonly used antimalarial drug, on the volume-regulated anion channel (VRAC) in cultured bovine pulmonary artery endothelial cells. We also examined its effects on other Cl(-) channels, i.e., the Ca(2+)-activated Cl(-) channel and the cystic fibrosis transmembrane conductance regulator, to assess the specificity of this compound for VRAC. At pH 7.4 mefloquine induced a fast and reversible block of the volume-sensitive chloride current (I(Cl,swell)), with an IC(50) value of 1.19 +/- 0.07 microM. The blocking efficiency increased with increasing extracellular pH (IC(50) value for pH 8.8 was 0.15 +/- 0.01 microM), indicating that this effect is mediated by the uncharged form of mefloquine. Ca(2+)-activated Cl(-) currents, I(Cl,Ca), activated by loading T84 cells via the patch pipette with 1 microM free Ca(2+) also were inhibited by mefloquine (IC(50) value 3.01 +/- 0.17 microM at pH 7.4). The cystic fibrosis transmembrane conductance regulator channel, transiently transfected in cultured bovine pulmonary artery endothelial cells, was not affected by 10 microM of the drug. This study describes for the first time effects of mefloquine on anion channels. Our data reveal a potent block of VRAC and Ca(2+)-activated Cl(-) channel at therapeutic concentrations. These results may contribute to a better understanding of the actions and side effects of this widely used antimalarial drug.

Animals↗
PubMed2000

KAI1 protein is down-regulated during the progression of human breast cancer.

The KAI1 gene was identified as a metastasis suppressor gene for human prostate cancer. Recently, we showed that KAI1 mRNA levels were higher in an immortal, normal-like breast epithelial cell line and nonmetastatic breast cancer cell lines but lower substantially in highly metastatic breast cancer cell lines. In this study, we examined KAI1 protein expression in breast cancer cell lines by Western blot and immunohistochemical study. KAI1 protein levels paralleled KAI1 mRNA levels and were inversely correlated with the metastatic potential of breast cancer cells. Furthermore, we examined KAI1 protein expression immunohistochemically in specimens from 81 patients with breast cancer and then correlated the findings with the clinical and histopathological parameters of the patients. High levels of KAI1 protein expression were found in normal breast tissues and noninvasive breast cancer (ductal carcinoma in situ). In contrast, KAI1 expression was reduced in most of the infiltrating breast tumors. We found that, in general, more malignant tumors demonstrated significantly lower KAI1 expression (P = 0.004). Additionally, among 29 specimens demonstrating multiple stages of malignancy within a single specimen, 23 demonstrated significant differences in KAI1 expression between benign breast tissue, ductal carcinoma in situ, and invasive carcinoma. The higher the incidence for malignancy within a given specimen, the lower the KAI1 expression (P < 0.001). These data suggest that in advanced breast cancer, KAI1 expression is down-regulated. Therefore, KAI1 may be a potentially useful indicator of human breast cancer progression.

Antigens, CD↗
PubMed2000

[Construction and expression of coexpression plasmid of carcinoembryonic antigen and Newcastle disease virus HN gene].

The eukaryotic expression plasmid (pcDNA3-CEA) containing with the gene coding for the Carcinoembryonic antigen(CEA) had been gotten with RT-PCR and gene recombination techniques. Using enzymolysis, ligation and other techniques, an eukaryotic coexpression plasmid(pcDNA3-CEA/HN) containing two expression unites of CEA and Newcastle disease virus HN gene that may have the function of immunoenhancement had been constructed. The plasmid will lay a foundation for further researching CEA nucleiotide vaccine, adjuvant and their effect of special antitumor immune.

Carcinoembryonic Antigen↗
PubMed2000

[Insulin secretion and resistance during pregnancy in women with glucose intolerance].

OBJECTIVE: To investigate whether insulin secretion and resistance are different in glucose tolerant and intolerant women with normal pre-pregnant body mass index (BMI) during late pregnancy and to find out if there is association between gestational diabetes and insulin resistance syndrome. METHODS: On the basis of a 4-hour oral glucose tolerance test (OGTT), 32 gestational diabetes mellitus (GDM) patients, 21 gestational impaired glucose tolerant (GIGT) patients, and 50 normal glucose tolerant (NGT) cases were selected from uncomplicated pregnant women. Those had normal pre-pregnant BMI who had a 1-hour 50-g glucose-screening test (> or = 7.2 mmol/L), performed between 24-28 weeks of gestation. During the OGTT, several indexes of insulin resistance, insulin secretion, lipid metabolism were measured in addition to the standard glucose measurements. RESULTS: Glucose area under curve (GAUC), insulin area under curve (IAUC), insulin sensitivity index (ISI) transformed to natural logarithm and triglycerides (TG) are all significantly higher (P < 0.05) in GDM women. The means of these indexes in GDM group are 26.3 mmol/L.h-1, 276.5 mU/L.h-1, 4.2 and 3.2 mmol/L, respeetively. On the other hand, however, the differences of these indexes (except TG) between GIGT and NGT women are not statistically significant. The ratio of IAUC/GAUC has an increasing trend from GDM group, GIGT group to NGT group (10.5, 11.4 and 11.7, respectively), but the difference is not statistically significant. Multiple correlation coefficient study demonstrated that ISI is significantly positively correlated with GAUC, IAUC and TG (P < 0.01). CONCLUSIONS: Compared with NGT women, GDM women has impaired insulin secretion, abnormally increased insulin resistance, and relatively dyslipidemia. GDM seems to be a component of the syndrome of insulin resistance that provides an excellent model for study and prevention in a relatively young aged group.

Diabetes, Gestational↗
PubMed2000

[Protein expression of human progesterone receptor isoforms A and B in uterine leiomyoma].

OBJECTIVE: To investigate the role of two isoforms of human progesterone receptor A (hPR-A) and B (hPR-B) in the development of uterine leiomyoma, their distribution and expression in leiomyoma were detected. METHODS: The tissues of leiomyoma and normal myometrium from 30 uteri, which were excised for leiomyoma, were used for the localization and quantification of protein of the two isoforms. Immunohistochemistry and Western blot were applied respectively. RESULTS: Both hPR-A and hPR-B were nuclear receptors. Concentrations of hPR-(A + B) and hPR-A in leiomyoma were higher than those in normal myometrium (295,796 +/- 90,856, 256,275 +/- 98,560; P = 0.042, P = 0.000,563). Both isoforms were presented in leiomyoma and normal myometrium, with a consistent dominance of hPR-B over hPR-A. More expression of hPR-A was found during secretive phase than proliferative phase, not only in leiomyoma but also in normal myometrium (P = 0.037, P = 0.024). CONCLUSIONS: The development of uterine leiomyoma seems to be related with the progesterone receptor isoforms, especially hPR-A.

Adult↗
PubMed2000

[Clinical observation of elderly idiopathic nephrotic syndrome treated with integrated traditional Chinese and Western medicine].

OBJECTIVE: To observe the clinical effect of integrated traditional Chinese and western medicine (TCM-WM) in treating the elderly idiopathic nephrotic syndrome (INS). METHODS: Eighty-two patients of the elderly INS were randomly divided into the TCM-WM group and the control group. Forty-one patients of the TCM-WM group were treated with prednisone, Cytoxan (CTX) and Chinese medicinal herbs according to Syndrome-type, the other 41 patients of the control group were treated with WM alone. Clinical remission rate, adverse reaction, recurrence rate and remission period were observed. RESULTS: The complete remission rate and total remission rate of the TCM-WM group were 58.5% and 85.4%, significantly higher than those of the control group (39.0%, 63.4%, P < 0.01). The adverse reaction rate of the TCM-WM group (36.6%) was significantly lower than that of the control group (80.5%, P < 0.01). A follow-up of 35.1 +/- 9.7 months showed that there was no significant difference in the recurrence rate between two groups (P > 0.05), but the average remission period (30.6 +/- 3.8 months) of the TCM-WM group was significantly longer than that of the control group (12.7 +/- 3.7 months, P < 0.01). CONCLUSION: TCM-WM treatment is obviously superior to treatment with WM alone in increasing clinical remission rate, relieving adverse reaction rate and extending remission period.

Aged↗
PubMed2000

[The relationship between vascular endothelial growth factor, microvascular density, lymph node metastasis and prognosis of breast carcinoma].

OBJECTIVE: To investigate the relationship between vascular endothelial growth factor (VEGF) microvascular density (MVD), lymph node metastasis and prognosis of breast carcinoma (BC). METHODS: VEGF protein expression and MVD in 92 cases of BC and VEGF mRNA expression in part of the cases were studied by immunohistochemistry methods and reverse-transcription polymerase chain reaction (RT-PCR) technique. RESULTS: VEGF mRNA expression in BC tumor tissues were higher than those in adjacent normal tissues. Increment of both VEGF(121) and VEGF(165) showed significant difference (P < 0.05 approximately 0.01). In addition, VEGF(145) expression was also observed in BC. There was a close positive correlation between VEGF and MVD (r = 0.702, P < 0.01). VEGF protein expression and MVD correlated significantly with lymph node metastasis and tumor relapse (P < 0.05 approximately 0.01). The time period of relapse-free-survival (RFS) in the patient group with high VEGF expression and MVD was significantly lower than RFS in the group with low VEGF expression and MVD (P < 0.01). CONCLUSION: VEGF is highly related to angiogenesis of BC. The increase of VEGF and MVD may promote lymph node metastasis and relapse of BC. VEGF and MVD may have prognostic value in RFS of BC patients.

Adult↗