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Biomedical subjects

X Lei

Publications and source records attributed to X Lei.

At least 19 recordsLinked to original sources
PubMed2006

Gender differences in renal nuclear receptors and aryl hydrocarbon receptor in 5/6 nephrectomized rats.

This study was aimed at delineating molecular pathways essential in gender-different pathogenesis of chronic kidney diseases (CKD). Renal transcripts of nuclear receptors and metabolic enzymes in male and female kidneys from 5/6 nephrectomized (Nx) rats 7 weeks post-Nx were examined using branched DNA signal amplification assay. Nx-males had marked kidney injury coupled with anemia and malnutrition. Nx-females had moderate renal injury, and were free of albuminuria, anemia, and malnutrition. Nx-males had systemic and renal inflammation, which were largely absent in Nx-females. Blood 17beta-estradiol, testosterone, and corticosterone did not change, whereas urinary testosterone decreased in both genders. Compared to males, female kidneys had higher androgen receptor (AR) and aryl hydrocarbon receptor (AhR) but lower estrogen receptor alpha (ERalpha). Compared to Nx-males, female remnant kidneys had less decreases in ERalpha and peroxisome proliferator-activated receptor alpha (PPARalpha), had no induction of AR and decrease of acyl-CoA oxidase, whereas had induction of cytochrome P450 4a1 (Cyp4a1) but decrease of AhR. Renal protein expression of a 52-kDa isoform of Wilm's tumor 1 (WT1), transcription factor critical in nephrogenesis, decreased dramatically in Nx-males but largely preserved in Nx-females. In conclusion, gender divergences in basal expression and alteration of ERalpha, AR, AhR, WT1, and PPARalpha/Cyp4a1 during CKD may explain gender differences in CKD progression and outcome of renal transplantation.

Acyl-CoA Oxidase↗
PubMed2006

Risk factors for relapse after complete remission with high-dose therapy for multiple myeloma.

Complete remission (CR) is an important surrogate for long-term survival for patients with multiple myeloma. However, most patients achieving CR eventually relapse and die from their disease. To better define the predictors of relapse, we conducted a retrospective review of outcomes for patients who achieved CR after autografting at our institution. From January 1990 to December 2002, among >400 patients transplanted, 81 (54 males and 27 females) achieved CR. With a median follow up of 58 months for all surviving patients, the 5-year progression-free survival (PFS) was 33% [95% confidence interval (CI) = 23 - 44] and 5-year overall survival (OS) was 67% (95% CI = 54 - 77). Median PFS was 37 months and median OS has not yet been reached. On multivariate analysis, high tumor mass at diagnosis emerged as a predictor of poor outcome. We conclude that high tumor mass at diagnosis predicts a significantly shorter remission duration for myeloma patients undergoing autografting.

Adult↗
PubMed2006

Stiff skin syndrome.

Stiff skin syndrome is a rare disorder characterized by pronounced skin induration, mild hypertrichosis and limited joint mobility, predominantly on the buttocks and thighs. Many heterogeneous cases have been reported under the name of stiff skin syndrome. We present a case of stiff skin syndrome from China, the diagnosis based on the patient's typical clinical and histopathological features.

Child, Preschool↗
PubMed2005

Semiparametric estimation of proportional mean residual life model in presence of censoring.

A mean residual life function is the average remaining life of a surviving subject, as it varies with time. The proportional mean residual life model was proposed by Oakes and Dasu (1990, Biometrika77, 409-410) in regression analysis to study its association with related covariates in absence of censoring. In this article, we develop some semiparametric estimation procedures to take censoring into account. The proposed methodology is evaluated via simulation studies, and further applied to a clinical trial of chemotherapy in postoperative radiotherapy of lung cancer patients.

Antineoplastic Agents↗
PubMed2001

Heat shock and heat shock protein 70i enhance the oncolytic effect of replicative adenovirus.

Replication-competent viruses are currently being evaluated for their cancer cell-killing properties. These vectors are designed to induce tumor regression after selective viral propagation within the tumor. However, replication-competent viruses have not resulted heretofore in complete tumor eradication in the clinical setting. Recently, heat shock has been reported to partially alleviate replication restriction on an avian adenovirus (Ad) in a human lung cancer cell line. Therefore, we hypothesized that heat shock and overexpression of heat shock protein (hsp) would support the oncolytic effect of a replication-competent human Ad. To this end, we tested the oncolytic and burst kinetics of a replication-competent Ad after exposure to heat shock or to inducible hsp 70 overexpression by a replication-deficient Ad (Adhsp 70i). Heat-shock resulted in augmentation of Ad burst and oncolysis while decreasing total intracellular Ad DNA. Overexpression of hsp 70i also enhanced Ad-mediated oncolysis but did not decrease intracellular Ad DNA levels. We conclude that heat shock and Adhsp 70i enhance the Ad cell-killing potential via distinct mechanisms. A potential therapeutic implication would be the use of local hyperthermia to augment oncolysis by increasing the burst of replication-competent Ad. The role of hsp in Ad-mediated oncolysis should be additionally explored.

Adenoviruses, Human↗
PubMed2001

Settling statistics of hard sphere particles.

Direct imaging of settling, non-Brownian, hard sphere, particles allows measurement of particle occupancy statistics as a function of time and sampling volume dimension. Initially random relative particle number fluctuations, (2)>/ = 1, become suppressed, anisotropic, and dependent. Fitting to a simple Gaussian pair correlation model suggests a minute long ranged correlation leads to strong if not complete suppression of number fluctuations. Calflisch and Luke predict a divergence in velocity fluctuations with increasing sample volume size based on random (Poisson) statistics. Our results suggest this is not a valid assumption for settling particles.

Journal Article↗
PubMed2001

[Detection of hepatitis C virus from hepatocellular carcinoma and its relationship to hepatocarcinogenesis].

OBJECTIVE: To get an insight of the relationship between hepatitis C Virus (HCV) infection and hepatocellular carcinoma (HCC). METHODS: A molecular pathology research was performed. Liver specimens from 19 HCC cases with HCV infection only were detected for HCV antigen (HCAg) and HCV RNA with monoclonal antibody (McAb) against HCV NS3 antigen by means of immuno-histochemistry staining and in situ hybridization using Dig-labeled full-length HCV cDNA Probe. RESULTS: In 17 of 19 (89.5%) cases, positive expression of the antigen was observed; 11 of 19 (57.9%) cases were positive for HCV RNA. The viral antigen was expressed in cytoplasm and nucleus of para-cancerous hepatocytes and in cancer cells too, while the distribution of HCV RNA was only seen in cytoplasm of hepatocyte. CONCLUSION: These results strongly support the relationship between HCV infection and the occurrence of HCC. The nucleic distribution of HCAg suggests a possible interaction between HCAg and the host genome, which may lead to hepatocarcinogenosis.

Aged↗
PubMed2000

Role of the transition metal in metallaborane chemistry. Reactivity of (Cp*ReH2)2B4H4 with BH3.thf, CO, and Co2(CO)8.

The reaction of Cp*ReCl4, [Cp*ReCl3]2, or [Cp*ReCl2]2 (Cp* = eta 5-C5Me5) with LiBH4 leads to the formation of 7-skeletal-electron-pair (7-sep) (Cp*ReH2)2(B2H3)2 (1) together with Cp*ReH6. Compound 1 is metastable and eliminates H2 at room temperature to generate 6-sep (Cp*ReH2)2B4H4 (2). The reaction of 2 with BH3.thf produces 7-sep (Cp*Re)2B7H7, a hypoelectronic cluster characterized previously. Heating of 2 with 1 atm of CO leads to 6-sep (Cp*ReCO)(Cp*ReH2)B4H4 (3). Both 2 and 3 have the same bicapped Re2B2 tetrahedral cluster core structure. Monitoring the reaction of 2 with CO at room temperature by NMR reveals the formation of a 7-sep, metastable intermediate, (Cp*ReCO)(Cp*ReH2)(B2H3)2 (4), which converts to 3 on heating. An X-ray structure determination reveals two isomeric forms (4-cis and 4-trans) in the crystallographic asymmetric unit which differ in geometry relative to the disposition of the metal ancillary ligands with respect to the Re-Re bond. The presence of these isomers in solution is corroborated by the solution NMR data and the infrared spectrum. In both isomers, the metallaborane core consists of fused B2Re2 tetrahedra sharing the Re2 fragment. On the basis of similarities in electron count and spectroscopic data, 1 also possesses the same bitetrahedral structure. The reaction of 2 with CO2(CO)8 results in the formal replacement of the four rhenium hydrides with a 4-electron CO2(CO)5 fragment, thereby closing the open face in 2 to produce the 6-sep hypoelectronic cluster (Cp*Re)2CO2(CO)5B4H4 (5). These reaction outcomes are compared and contrasted with those previously observed for 5-sep (Cp*Cr2)2B4H8.

Journal Article↗
PubMed2000

Fine-tuning of metallaborane geometries: chemistry of iridaboranes derived from the reaction of

From reaction of [(Cp*Ir)2HxCl(4-x)] (x=1, 0) and LiBH4, arachno-[[Cp*IrH2]B3H7](1) is produced in moderate yield concurrently with [Cp*IrH4]. In contrast, reaction of [(Cp*Ir)2H2Cl2] with LiBH4 results in arachno-[[Cp*IrH]2(mu-H)B2H5] (3) in high yield at room temperature but a mixture of 1 and [[Cp*IrH]2(mu-H)BH4] (2) at 0 degrees C. BH3 x THF converts 1 to arachno-[(Cp*IrHB4H9] (4) and 2 to 3 with 1 as a minor product. Further, reaction of 3 with excess of BH3 x THF results in formation of nido-[[Cp*Ir]2-(mu-H)B4H7] (6) formed by loss of H2 from the intermediate arachno-[[Cp*IrH]2B4H8] (5). Reaction of 1 with [Co2(CO)8] permits the isolation of two metallaboranes, arachno-[[Cp*Ir(CO)]-B3H7] (7) and nido-[1-[Cp*Ir]-2,3-Co2-(CO)4(mu-CO)B3H7] (8). Treatment of 4 with [Co2(CO)8] gives only one single mixed-metal metallaborane nido-[1-[Cp*Ir]-2-Co(CO)3B4H7 (9) in high yield. Finally, pyrolysis of 8 results in loss of hydrogen and formation of pileo-[1-[Cp*Ir]-2,3-Co2(CO)5B3H5] (10) with a BH-capped square-pyramidal structure. With kinetic control rational synthesis of a variety metallaboranes has been achieved by varying the number of chlorides in the monocyclopentadienylmetal halide dimer, reaction temperature, types of monoborane, and metal fragment sources.

Journal Article↗
PubMed1999

Influence of cell deformation on leukocyte rolling adhesion in shear flow.

Blood cell interaction with vascular endothelium is important in microcirculation, where rolling adhesion of circulating leukocytes along the surface of endothelial cells is a prerequisite for leukocyte emigration under flow conditions. HL-60 cell rolling adhesion to surface-immobilized P-selectin in shear flow was investigated using a side-view flow chamber, which permitted measurements of cell deformation and cell-substrate contact length as well as cell rolling velocity. A two-dimensional model was developed based on the assumption that fluid energy input to a rolling cell was essentially distributed into two parts: cytoplasmic viscous dissipation, and energy needed to break adhesion bonds between the rolling cell and its substrate. The flow fields of extracellular fluid and intracellular cytoplasm were solved using finite element methods with a deformable cell membrane represented by an elastic ring. The adhesion energy loss was calculated based on receptor-ligand kinetics equations. It was found that, as a result of shear-flow-induced cell deformation, cell-substrate contact area under high wall shear stresses (20 dyn/cm2) could be as much as twice of that under low stresses (0.5 dyn/cm2). An increase in contact area may cause more energy dissipation to both adhesion bonds and viscous cytoplasm, whereas the fluid energy input may decrease due to the flattened cell shape. Our model predicts that leukocyte rolling velocity will reach a plateau as shear stress increases, which agrees with both in vivo and in vitro experimental observations.

Adsorption↗
PubMed1999

[GB virus-C infection in Chinese patients with hepatocellular carcinoma].

Hepatitis B and C viruses (HBV, HCV) are closely related with hepatocellular carcinoma(HCC). The association between the new discovered GB-virus C (GBV-C) and HCC has not yet been known. In this study, 124 HCC patients were detected for the prevalence of GBV-C RNA by the one-step nested reverse transcription polymerase chain reaction (RT-PCR) and followed by hybridization using GBV-C probes located at 3'-untranslated region (3'-UTR) from its reported genomes. The results showed that 33 of 124 (26.6%) HCC cases were GBV-C RNA positive, including 12 cases positive HBsAg and anti-HCV, and 3 for cases negative HBsAg and anti-HCV. The clinical background of the patients with HBsAg and/or anti-HCV who were also positive for GBV-C RNA did not differ from the background of those who were negative for GBV-C RNA except the ratio of blood transfusion history. In conclusion, GBV-C has a high prevalence in Chinese HCC patients. Even though no sufficient data supports the causality of GBV-C on hepatocarcinogenesis, further researches aimed at whether GBV-C infection aggravates the incidence of HCC are warranted.

Adult↗
PubMed1999

[Evaluation of effectiveness of hepatitis B plasma derived vaccine and a survey of hepatitis C virus infection in preschool children in Chengdu, Sichuan].

This study was undertaken to evaluate the effectiveness of hepatitis B plasma-derived vaccine and investigate the character of hepatitis C virus infection in preschool children. The anti-HBs, HBsAg and anti-HCV of 985 plasma samples were examined by ELISA. The results showed that the positive rate of HBsAg in the children (aged < 7 yr) in the communities was 0.89% and the effectiveness of the vaccine was 91.38%. The positive rate of anti-HBs decreased with the increase in age; the positive rate of HBsAg did not increase with age. The positive rate of HBsAg was as high as 4.69% in the children from hospitals, so supervision and enhanced vaccination should be administered properly in this group. The positiverate of anti-HCV was 1.18% in the communities, but 3.17% in hospitals. It is worthy to investigate how children get infected with HCV.

Child, Preschool↗
PubMed1999

[Immunohistochemical detection of hepatitis C virus antigen from hepatocellular carcinoma].

To investigate the infection of HCV and the expression of HCV antigen (HCAg) in HCC, immunohistochemical protocol was performed on tumorous liver tissues from 40 patients with HCC to detect HCAg and hepatitis B virus surface antigen (HBsAg) simultaneously. The results showed that the positive rates for HCAg and HBsAg were 17.5% (7/40) and 70% (28/40) respectively. HBsAg and HCAg were simultaneously detected in six of 40 cases and only one case had HCAg positive alone in the liver tumorous tissue. The positive signals were localized in diffuse cytoplasm of hepatocytes and the positively stained cells were mainly distributed in local pattern. The results suggested that HCV infection did exist in some cases of HCC, so HCV might be a viral risk factor in addition to HBV in the genesis of HCC in China.

Adult↗