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Biomedical subjects

Wei Shen

Publications and source records attributed to Wei Shen.

At least 37 records · Page 2Linked to original sources
PubMed2006

Tuning the erosion rate of artificial protein hydrogels through control of network topology.

Erosion behaviour governs the use of physical hydrogels in biomedical applications ranging from controlled release to cell encapsulation. Genetically engineered protein hydrogels offer unique means of controlling the erosion rate by engineering their amino acid sequences and network topology. Here, we show that the erosion rate of such materials can be tuned by harnessing selective molecular recognition, discrete aggregation number and orientational discrimination of coiled-coil protein domains. Hydrogels formed from a triblock artificial protein bearing dissimilar helical coiled-coil end domains (P and A) erode more than one hundredfold slower than hydrogels formed from those bearing the same end domains (either P or A). The reduced erosion rate is a consequence of the fact that looped chains are suppressed because P and A tend not to associate with each other. Thus, the erosion rate can be tuned over several orders of magnitude in artificial protein hydrogels, opening the door to diverse biomedical applications.

Amino Acid Sequence↗
PubMed2006

Efficient and simple production of transgenic mice and rabbits using the new DMSO-sperm mediated exogenous DNA transfer method.

A high efficient and simple transgenic technology on mice and rabbits to transfect spermatozoa with exogenous DNA/DMSO complex to obtain transgenic offspring, which is namely called DMSO-sperm mediated gene transfer (SMGT). Mouse sperm could be either directly transfected via injection into testis or cultured in vitro with the plasmed DNA containing the enhanced green fluorescent protein (EGFP) that could be expressed in the embryos and offspring. Then, 36 living transgenic rabbits were produced using the same technology, and the transgenic ratio of 56.3% was detected using PCR and Southern blot. As the controls, the transgenic ratios of 39.6% and 47.8% have also been tested using the liposomes mediated technology of Tfx-50 Reagent or Lipefectamin-2000, respectively. The results show that the female transgenic rabbits, as the mammary gland bioreactor models, could express the human tissue plasminogen activator mutant (htPAm) in their mammary cells when they are adult.

Animals↗
PubMed2006

Mouse oocytes derived from fetal germ cells are competent to support the development of embryos by in vitro fertilization.

Mouse oocyte development in vitro has been studied in the past several years, but no evidence showed that the fertilizable oocytes could be obtained from the fetal mouse germ cells before the formation of the primordial follicles. In this study, an efficient and simple method has been established to obtain the mature oocytes from the fetal mouse germ cells at 16.5 days post-coitum (dpc). For the initial of follicular formation, fetal mouse 16.5 dpc ovaries were transplanted to the recipient under the kidney capsule, and the ovaries were recovered after 14 days. Subsequently, the growing preantral follicles in the ovarian grafts were isolated and cultured in vitro for 12 days. Practically, the mature oocytes ovulated from the antral follicles were able to be fertilized in vitro and support the embryonic development. The results demonstrate that the fetal mouse 16.5 dpc germ cells are able to form primordial follicles with the ovarian pregranulosa cells during the period of transplantation in the ectopic site, and the oocytes within the growing follicles are able to mature in vitro, then are able to support the embryonic development.

Animals↗
PubMed2006

Waist circumference correlates with metabolic syndrome indicators better than percentage fat.

OBJECTIVE: Percent fat is often considered the reference for establishing the magnitude of adipose tissue accumulation and the risk of excess adiposity. However, the increasing recognition of a strong link between central adiposity and metabolic disturbances led us to test whether waist circumference (WC) is more highly correlated with metabolic syndrome components than percent fat and other related anthropometric measures such as BMI. RESEARCH METHODS AND PROCEDURES: BMI, WC, and percent fat, measured by DXA, were evaluated in 1010 healthy white and African-American men and women [age, 48.3 +/- 17.2 (standard deviation) years; BMI, 27.0 +/- 5.3 kg/m(2)]. The associations of BMI, WC, and percent fat with age and laboratory-adjusted health risk indicators (i.e., serum glucose, insulin, triglycerides, high-density lipoprotein cholesterol, blood pressure) in each sex and ethnicity group were examined. RESULTS: For 18 of 24 comparisons, the age- and laboratory-adjusted correlations were lowest for percent fat and in 16 of 24 comparisons were highest for WC. Fifteen of the between-method differences reached statistical significance. With health risk indicator as the dependent variable and anthropometric measures as the independent variable, the contribution of percent fat to the WC regression model was not statistically significant; in contrast, adding WC to the percent fat regression model did make a significant independent contribution for most health risk indicators. DISCUSSION: WC had the strongest associations with health risk indicators, followed by BMI. Although percent fat is a useful measure of overall adiposity, health risks are best represented by the simply measured WC.

Adiposity↗
PubMed2006

Human lactoferrin transgenic rabbits produced efficiently using dimethylsulfoxide-sperm-mediated gene transfer.

Transgenic animal mammary gland bioreactors are used to produce recombinant proteins. However, it is difficult to validate whether these transgenic domestic animals are able to express the recombinant protein efficiently in their mammary glands before the birth of transgenic offspring. In the present study, a simple and efficient method was established to evaluate the functionality of animal mammary gland tissue-expressed cassettes. The gene transfer vector pGBC2LF was constructed, and the expression of human lactoferrin (LF) gene was controlled by the goat beta-casein gene 5' flanking sequence. To obtain the most efficient transfection, the influence of DNA concentration, dimethylsulfoxide (DMSO) concentration, and the ratio of linear-to-circular DNA required for associating DNA with spermatozoa were evaluated. Transfection of exogenous DNA into rabbit spermatozoa was found to be efficient using 30 microg mL(-1) DNA, DMSO at a final concentration of 3%, and a 3 : 1 ratio of linear-to-circular DNA, with 29 of 85 (34.1%) in vitro-fertilised embryos being transgenic. Using DMSO-sperm-mediated gene transfer (DMSO-SMGT), 89 rabbit offspring were produced, with 46 of these (57.1%) being transgenic. As mammary gland bioreactor models, 17 of 21 (81%) transgenic female rabbits could express human LF protein in their glands. During lactation of the transgenic rabbits, the highest level of human LF protein expressed was 153 +/- 31 microg mL(-1), and the mean expression level in all of the transgenic rabbits was 103 +/- 20 microg mL(-1) in the third week, declining gradually after this time. Our results demonstrate that transgenic rabbits produced by DMSO-SMGT were able to express human LF protein in the correct tissue.

Animals↗
PubMed2006

Total-body skeletal muscle mass: estimation by dual-energy X-ray absorptiometry in children and adolescents.

BACKGROUND: Skeletal muscle (SM) is an important compartment but is difficult to quantify in children and adolescents. OBJECTIVE: We investigated the potential of dual-energy X-ray absorptiometry (DXA) for measuring total-body SM in pediatric subjects. DESIGN: A previously published adult DXA SM prediction formula was evaluated in children and adolescents aged 5-17 y (n = 99) who varied in pubertal maturation stage. SM estimated by whole-body magnetic resonance imaging (MRI) was used as the reference. The adult SM model was not accurate for subjects below Tanner stage 5 (n = 65; aged 5-14 y). New pediatric SM prediction models were therefore developed and validated in a separate group (n = 18). RESULTS: The adult DXA SM prediction model was valid in subjects at Tanner stage 5 but significantly (P < 0.001) overestimated SM in subjects below Tanner stage 5. New SM prediction formulas were developed with appendicular lean soft tissue (ALST) estimates by DXA as the main predictor variable (eg, model 1, ALST alone: R(2) = 0.982, SEE = 0.565 kg, P < 0.001). The new models were validated by the leave-one-out method and were cross-validated in a separate validation group. CONCLUSIONS: A previously reported adult DXA SM prediction model is applicable in children and adolescents late in pubertal development (Tanner stage 5). A new DXA SM prediction model was developed for prepubertal and pubertal subjects (Tanner stage </=4) aged >/=5 y. DXA thus provides an important opportunity for quantifying total-body SM mass across most of the human life span.

Absorptiometry, Photon↗
PubMed2006

Influence of angiogenin on the growth of A375 human melanoma cells and the expression of basic fibroblast growth factor.

Angiogenin was isolated as a tumor angiogenic factor solely on the basis of its angiogenic activity. Its expression is essential for melanoma progression and metastasis. Many studies have mainly focused on how it induces angiogenesis, which allows further melanoma growth and metastasis. Here, we investigated the effects of angiogenin on melanoma cell growth and studied its influence on the expression and function of the basic fibroblast growth factor. We transfected the angiogenin gene in the sense and antisense orientation into A375 cells, and obtained stable angiogenin under-expressing and over-expressing transfectants. We found that in the angiogenin antisense transfectants, the cell proliferation was decreased and the basic fibroblast growth factor-induced cell proliferation was inhibited, but the expression of basic fibroblast growth factor was increased. In contrast, in the angiogenin sense transfectants, the cell proliferation was increased, and the basic fibroblast growth factor-induced cell proliferation was also increased. The expression of basic fibroblast growth factor, however, was decreased. In conclusion, we demonstrated that, besides its angiogenic activity, angiogenin also directly contributes to A375 cell proliferation and is required for the basic fibroblast growth factor to induce cell proliferation. We also demonstrated that the endogenous angiogenin expression levels affect the expression of basic fibroblast growth factor in A375 cells. By targeting angiogenin, therefore, one may find a potential therapeutic approach to human malignant melanoma.

Angiogenesis Inducing Agents↗
PubMed2006

Gene order in human alpha-globin locus is required for their temporal specific expressions.

The human alpha-globin cluster represents a unique model of transcriptional regulation and provides challenges to the current understanding of interactions between distal and proximal regulatory elements. Although the gene proximal regions are believed to possess almost all the necessary elements for temporal and spatial specificity of gene transcription, it is still not clear whether the relative distance of embryonic zeta- and fetal/adult alpha-genes to their distal regulatory element alpha-URE plays any role in transcriptional switching. To investigate the role of gene order in regulating temporal expression, we inverted the entire structure gene region of human alpha-globin locus in a BAC clone bringing alpha-genes closest to alpha-URE and zeta-gene the farthest away. Expression analysis of the reverted locus in transgenic mice showed that alpha-globin genes, now relocated closer to alpha-URE, maintained their expression levels through all developmental stages. However, the zeta-globin gene suffered a total loss at both embryonic and fetal/adult stages. It indicates that proximal location of zeta-globin gene to alpha-URE is necessary for its normal embryonic expression and necessary to prevent embryonic expression of the alpha-globin gene. We proved that, in the human alpha-globin gene cluster, the normal order of structural genes relative to alpha-URE plays a crucial role in the regulation of developmental switching.

Animals↗
PubMed2006

Efficacy and safety of on-demand tadalafil for the treatment of erectile dysfunction in South-East Asian men.

AIM: Tadalafil is an inhibitor of phosphodiesterase type 5 used for the treatment of erectile dysfunction (ED). The efficacy and safety of tadalafil have been evaluated extensively in Western populations. Our aim was to assess the efficacy and safety of on-demand tadalafil for the treatment of ED in South-East Asian men. METHODS: This was a randomized, double-blind, placebo-controlled study of men with mild to severe ED of various etiologies randomized to receive placebo (n = 122), tadalafil 10 mg (n = 120), or tadalafil 20 mg (n = 125), taken as needed (maximum once daily) for 12 weeks. Efficacy assessments included the International Index of Erectile Function (IIEF), the Sexual Encounter Profile (SEP) diary, and a Global Assessment Question (GAQ). RESULTS: Men from China, Singapore, and the Philippines participated in this trial (n = 367). Compared with placebo, tadalafil significantly improved erectile dysfunction on all efficacy outcomes (P < 0.001). Patients receiving tadalafil 10 mg and 20 mg experienced a significant mean improvement of 8.1 and 8.7, respectively, in the IIEF Erectile Function (IIEF-EF) domain score from baseline (vs placebo 2.4, P < 0.001). In patients receiving tadalafil 10 mg and 20 mg, the mean per-patient success rate for intercourse attempts (SEP3) was 62% and 70%, respectively, compared with 32% for the placebo group (P < 0.001). Of patients who received tadalafil 10 mg and 20 mg, 81% and 86% reported improved erections at endpoint (GAQ) compared with 44% in the placebo group (P < 0.001). The most common adverse events reported by patients were headache, back pain, dyspepsia, and dizziness. CONCLUSIONS: Tadalafil was an effective and well-tolerated treatment for South-East Asian men with ED.

Adult↗
PubMed2006

Biochemical properties of a thermostable phytase from Neurospora crassa.

A gene (Ncphy) encoding a putative phytase in Neurospora crassa was cloned and expressed in Pichia pastoris, and the biochemical properties of the recombinant protein were examined in relation to the phytic acid hydrolysis in animal feed. The recombinant phytase (rNcPhy) hydrolyzed phytic acid with a specific activity of 125 U mg-1, Km of 228 micromol L-1, Vmax of 0.31 nmol (phosphate) s-1 mg-1, a temperature optimum of 60 degrees C and a pH optimum of 5.5 and a second pH optimum of 3.5. The enzyme displayed pH stability around pH 3.5-9.5 and showed satisfactory thermostability at 80 degrees C. The phytase from N. crassa has potential for improving animal feed processing at higher temperatures.

6-Phytase↗
PubMed2006

[Accelerated somatic cell senescence and changes in p16INK4a expression after exogenous DNA transfection].

During the transfection of mouse embryonic fibroblasts (MEF), we found these cells became senescent, appearing enlarged with hollow cytoplasm and multinucleated. The telomere lengths of these senescent MEFs were significantly shorter than primary untransfected MEFs. In senescent MEF cells, DNA methylation of p16INK4a 5'-regulatory region showed gradual reduction as cells aged. RT-PCR and Northern blot demonstrated that the expression of p16INK4a in transfected senescent cells was 12-16 times more than primary cells. The senescent transfected MEF cells as donors of nuclei could support the early development of cloned embryos after nuclear transfer.

Animals↗
PubMed2006

[Nuclear transfer of goat somatic cells transgenic for human lactoferrin].

Transgenic animal mammary gland bioreactors are being used to produce recombinant proteins with appropriate post-translational modifications, and nuclear transfer of transgenic somatic cells is a more powerful method to produce mammary gland bioreactor. Here we describe efficient gene transfer and nuclear transfer in goat somatic cells. Gene targeting vector pGBC2LF was constructed by cloning human lactoferrin (LF) gene cDNA into exon 2 of the milk goat beta-casein gene, and the endogenous start condon was replaced by that of human LF gene. Goat fetal fibroblasts were transfected with linearized pGBC2LF and 14 cell lines were positive according to PCR and Southern blot. The transgenic cells were used as donor cells of nuclear transfer, and some of reconstructed embryos could develop to blastocyst in vitro.

Animals↗
PubMed2006

Fuzzy neural network for flow estimation in sewer systems during wet weather.

Estimation of the water flow from rainfall intensity during storm events is important in hydrology, sewer system control, and environmental protection. The runoff-producing behavior of a sewer system changes from one storm event to another because rainfall loss depends not only on rainfall intensities, but also on the state of the soil and vegetation, the general condition of the climate, and so on. As such, it would be difficult to obtain a precise flowrate estimation without sufficient a priori knowledge of these factors. To establish a model for flow estimation, one can also use statistical methods, such as the neural network STORMNET, software developed at Lyonnaise des Eaux, France, analyzing the relation between rainfall intensity and flowrate data of the known storm events registered in the past for a given sewer system. In this study, the authors propose a fuzzy neural network to estimate the flowrate from rainfall intensity. The fuzzy neural network combines four STORMNETs and fuzzy deduction to better estimate the flowrates. This study's system for flow estimation can be calibrated automatically by using known storm events; no data regarding the physical characteristics of the drainage basins are required. Compared with the neural network STORMNET, this method reduces the mean square error of the flow estimates by approximately 20%. Experimental results are reported herein.

Calibration↗
PubMed2006

[A clinical analysis of liver disease patients with abnormal glucose metabolism].

OBJECTIVE: To study the clinical features of liver disease patients with abnormal glucose metabolism. METHODS: Liver functions and levels of FPG, PPG, FINS, PINS, FCP, and PCP in 91 chronic hepatitis B patients with abnormal glucose metabolism (62 had liver cirrhosis) were analyzed. RESULTS: (1) The incidence of hepatogenic impaired glucose tolerance (IGT) and of diabetes mellitus (DM) in hepatitis B patients with liver cirrhosis (20.53%; 24.11%) were higher than those without cirrhosis (3.82%; 1.64%; P<0.05, P<0.01). (2) There were no diabetic symptoms among any of the hepatogenic IGT and DM patients. 12 of 19 chronic hepatitis B patients with primary DM and 6 of 12 hepatitis B associated liver cirrhosis patients with primary DM had diabetic symptoms. (3) The levels of FPG and PPG in chronic hepatitis B patients with hepatogenic IGT and DM were lower than those in the patients with primary DM (P<0.05), but the levels of PINS and PCP in chronic hepatitis B patients with hepatogenic IGT and DM were higher than those in the patients with primary DM (P<0.05). (4) There were no differences in the levels of FPG and PPG between the hepatitis B associated liver cirrhosis patients with hepatogenic DM and those with primary DM (P<0.05). The levels of FINS, PINS, FCP, and PCP were higher in the hepatitis B associated liver cirrhosis patients with hepatogenic DM than those in the hepatitis B associated liver cirrhosis patients with primary DM (P<0.05). The levels of FPG and PPG in the hepatogenic DM patients were higher than those in the hepatogenic IGT patients (P<0.05), but their levels of FINS, PINS, FCP and PCP were lower than those in the hepatogenic IGT patients (P<0.05, P<0.01). CONCLUSION: Hepatogenic IGT and DM are always secondary in severe liver cirrhosis patients, who always showed no diabetic symptoms. The chronic hepatitis B patients with hepatogenic DM had increased insulin secretion, while the hepatitis B associated liver cirrhosis patients with hepatogenic DM had decreased insulin secretion.

Blood Glucose↗
PubMed2006

[Vocal sound study in supracricoid partial laryngectomy].

OBJECTIVE: Vocal sound was studied in 21 patients underwent supracricoid partial laryngectomy using Dr. Speech. METHOD: Vocal sound tests and frequency spectrum analysis were used in 4 different approaches (CHEP, CHP, TCHEP, TCHP) both before and after the operation. RESULT: Vibration pattern of new glottidis formed after the four different operation approaches was approximately the same demonstrating an augmentation of mucous membrane fluctuation. This vibration pattern were increasing and stabilizing gradually with time. CONCLUSION: Retaining on both sides and one side in supracricoid partial laryngectomy facilitates restoration of vocal function.

Aged↗
PubMed2006

[Construction of an engineering strain producing alkaline pectate lyase with pHSh].

The structure gene PL from Bacillus subtilis WSHB04-02 encoding pectate lyase was amplified by PCR. The pET22b(+) vector, with leader sequence PelB, harboring PL gene was constructed. From pET22b(+) PL, the fragment of PL and leader sequence PelB was amplified by PCR together, which was transformed into E. coli JMI109. The expression of PL in E. coli JM109 was not evidently different from E. coli BL21DE3 (pET22b(+) PL) which promoter is T7. SDS-PAGE analysis showed that the molecular weight of expressed recombinant PL was about 43 kDa which was the same as calculated value. The results indicated the expression of pHsh PL in E. coli JM109, Hsh as a promoter, was satisfied and low-cost. It is significant for large-scale fermentation of pectate lyase.

Bacillus subtilis↗