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Biomedical subjects

Wei Shen

Publications and source records attributed to Wei Shen.

At least 73 records · Page 4Linked to original sources
PubMed2005

[Evaluation of the effects of dense endoscopic ligation for bleeding esophageal varices].

OBJECTIVE: To evaluate the short-term and long-term effects of dense endoscopic variceal ligation (DEVL) for bleeding esophageal varices. METHODS: Patients with acute or with a history of esophageal variceal bleeding underwent regular DEVLs with a 2-3 week interval between 2 sessions until their varices disappeared at the lower 5-6 cm part of the esophagus. Follow-up study and gastroscopy were performed at 3, 6 and 12 months after the final DEVL in all patients. The results at 3 months were classified as short-term effects and those after 6 months as long-term ones. RESULTS: 126 patients underwent DEVLs with 403 sessions and 3641 ligations; each patient was ligated with a mean of 3.2 sessions and at 28.9 points. The cure rate of acute variceal bleeding was 100.0%; short-term rate of variceal eradication was 94.4% and variceal rebleeding occurred in 3.9% patients. After a mean of 22.3 months follow-up period, the recurrence of esophageal varices was observed in 11.9% patients, but the variceal rebleeding rate was only 3.2% and no patients died from it. CONCLUSION: DEVL was very useful and effective in both short-term and long-term variceal eradication and prevention of variceal rebleeding.

Adult↗
PubMed2005

[Preparation of lung targeting azithromycin liposomes and its tissue distribution in mice].

AIM: To prepare lung targeting azithromycin cationic liposomes and to observe its tissue distribution in mice. METHODS: The azithromycin cationic liposomes were prepared by thin film method with freeze-thawing steps. HPLC method was established and validated for the determination of azithromycin in tissues of mice. RESULTS: The particle size of the liposomes was 6.582 microm with zeta potential of +19.5 mV. The entrapment efficiency was more than 75%. The liposomes was stable in 6 months stored at 4 degrees C. The release in vitro was characterized by Higuchi equation. Azithromycin liposomes and free azithromycin solution were injected intravenously at a dose of 80 mg x kg(-1) to mice. Compared with solution, liposomes were characterized by slower clearance, increased half-life and the AUC increased by 7.4 fold in lung. CONCLUSION: Thin film method with freeze-thawing steps could increase the entrapment efficiency and increase the particle size of azithromycin liposomes. After modification of lipid membrane with stearylamine, the cationic liposomes were prepared. The azithromycin concentration and AUC increased in lung after iv administration to mice of the cationic liposomes. This offered a good information for preparing liposomes targeting on the lung.

Animals↗
PubMed2005

[Glyoxylate cycle is required for the overproduction of glutamate but is not essential for Corynebacterium glutamicum growth on glucose].

The glyoxylate cycle was hypothesed to be indispensable for glutamate overproduction in coryneform bacteria, for it was thought to fulfill anaplerotic functions and to supply energy during the growth phase. During glutamate overproduction phase, however, it has been noted that the high level of the cycle is detrimental to the glutamate production. In order to clarify the relationship between the glutamate production and the glyoxylate cycle, a chromosomal aceA-disrupted mutant of wild-type C. glutamicum ATCC 13032 was constructed. The isocitrate lyase (ICL) activity of the parental strain was 0.011 u/mg of protein and reached 1.980 u/mg of protein after acetate induction; the mutant strain WTdeltaA, however, had no detectable ICL activity and was no longer able to grow on minimal medium with acetate as the sole carbon source. Compared with the wild-type C. glutamicum WT, the mutant strain WTdeltaA, exhibited the same growth rate with glucose as the sole carbon source, indicating glyoxylate cycle is not required for its growth on glucose. On the contrary, the glutamate production in WTdeltaA was severely impaired and more residual glucose was found in the fermentation broth at the end of fermentation with the mutant strain than with the wild-type strain. Further investigations into the relationship between the glutamate production and the glyoxylate cycle are under the way, which may help to elucidate the mechanism of glutamate overproduction.

Corynebacterium glutamicum↗
PubMed2005

[The changes of ROS and mitochondria membrane potential in HepG2 cells on the pressure of cisplatin].

OBJECTIVE: To explore the changes and significance of the level of reactive oxygen species (ROS) and mitochondria membrane potential (Delta Psi) in HepG2 cells under the stress of cisplatin (CDDP). METHODS: HepG2 cells were incubated with CDDP. The changes in the level of ROS were determined by a probe (2,7-dichloro fluorescein-ciactate, DCFH-DA) and the changes of Delta Psi were reflected as changes of intensities of fluorescence seen under a laser scan microscope using a probe (rhodamine-123). All these changes in cells at 0 h, 24 h, 48 h, 72 h, 120 h, 168 h were dynamically observed. RESULTS: The level of ROS was much higher after the CDDP treatment than the non-treated, and the increase lasted for 24 h and 48 h. Then it started to decrease at 72 h, gradually returning to normal level at 120 h. Under the selective pressure of CDDP, the fluorescence intensity of rhodamine-123 in HepG2 cells was decreasing at 24 h and 48 h, then gradually started to increase at 72 h. There were no such changes in the cells of the controls. CONCLUSION: The changes of ROS and Delta Psi in HepG2 cells under the pressure of CDDP suggest that the cells change themselves adapting to such pressures.

Carcinoma, Hepatocellular↗
PubMed2005

Pathogenesis and treatment to postoperative bile leakage: report of 38 cases.

BACKGROUND: Bile leakage remains a serious complication after biliary surgery. The aim of this study was to assess the etiology, diagnosis and treatment of postoperative biliary leakage. METHODS: Thirty-eight patients with biliary leakage we treated in recent 8 years were analyzed retrospectively. Among them, 8 patients had bilioenterostomy leakage, 7 accessory bile duct leakage, 7 cholecyst bed leakage, 6 leakage after removal of T-tube, 5 leakage after laparoscopic cholecystectomy, 3 leakage around T-tube, and 2 leakage caused by choledochal damage. Drainage was performed in 17 patients, reoperation in 13, drainage plus percutaneous transhepatic cholangio drainage (PTCD), endoscopic retrograde cholangiography (ERCP), endoscopic nasobiliary drainage (ENBD) and endostenting in 5, and drainage plus growth hormone in 3. RESULTS: In this series, 37 patients were cured, and 1 died of multiple organ dysfunction syndrome (MODS). These patients were hospitalized for 2 weeks to 8 weeks. The drainage group was hospitalized shorter than the undrainage group. CONCLUSIONS: A piece of white gauze can be used to touch surgical area in detecting biliary leakage intraoperatively. Mucous to mucous suture of the bile duct and appropriate time for removal of T-tube are recommended to prevent biliary leakage. Reoperation is essential to acute peritonitis. Drainage can be used if leakage don't diffuse or it occurs after pulling out T-tube. Drainage plus ERCP, ENBD, PTCD and drainage are effective.

Adult↗
PubMed2005

Pediatric obesity phenotyping by magnetic resonance methods.

PURPOSE OF REVIEW: Accurate measurement of adiposity in obese children is required for characterizing the condition's phenotype, severity, and treatment effects in vivo. Non-invasive and safe, magnetic resonance imaging and spectroscopy provide an important new approach for characterizing key aspects of pediatric obesity. This review focuses on recent advances in non-invasive magnetic resonance imaging and spectroscopy for quantifying total body and regional adiposity, mapping adipose tissue distribution, and evaluating selected metabolic disturbances in children. The aim is to provide an investigator-focused overview of magnetic resonance methods for use in the study of pediatric body composition and metabolism. RECENT FINDINGS: Whole body axial images can be rapidly acquired on most clinical magnetic resonance imaging scanners. The images can then be semi-automatically segmented into subcutaneous, visceral, and intramuscular adipose tissue. Specific pediatric studies of errors related to slice gap and number are available. The acquisition of scans in healthy and premature infants is now feasible with recent technological advances. Spectroscopic, Dixon, and other approaches can be used to quantify the lipid content of liver, skeletal muscle, and other organs. Protocol selection is based on factors such as subject age and cost. Particular attention should be directed towards identification of landmarks in growth studies. Recent advances promise to reduce the requirement of subjects to remain motionless for relatively long periods. SUMMARY: Magnetic resonance imaging and spectroscopy are safe, practical, and widely available methods for phenotyping adiposity in children that open new opportunities for metabolism and nutritional research.

Adipose Tissue↗
PubMed2005

[Construction of novel recombinant Escherichia coli capable of producing 1,3-propanediol].

The 1,3-propanediol oxidoreductase isoenzyme encoding gene (yqhD) from E. coli was amplified by PCR. yqhD was inserted in pEtac to yield the recombinant expression vector pEtac-yqhD. Over-expression of yqhD in E. coli JM109 was achieved with pEtac-yqhD. SDS-PAGE analysis showed an over-expressed recombinant product at about 43 kD, consistent with the molecular weight predicted from gene sequence. Compared with E. coli JM109 (pEtac), the 1,3-propanediol oxidoreductase isoenzyme activity of the recombinant E. coli (pEtac-yqhD) reached 120 u/mg protein under the induction of 1.0 mmol/L IPTG at 37 degrees C for 4 hours; at similar conditions, enzyme activity of E. coli JM109 (pEtac) was only 0.5 u/mg protein. The recombinant E. coli JM109 (pUCtac-dhaB, pEtac-yqhD) was constructed. After induction with 1.0 mmol/L IPTG, the recombinant strain could transform 50 g/L glycerol to 38 g/L 1,3-propanediol under aerobic conditions. This work demonstrated firstly that the 1,3-propanediol oxidoreductase isoenzyme could show high activity under aerobic conditions.

Aerobiosis↗
PubMed2005

Relationship of homocysteine and gene polymorphisms of its related metabolic enzymes with Alzheimer's disease.

OBJECTIVE: To investigate the relationship of plasma homocysteine (Hcy) levels and the gene polymorphisms of N5, N10-methylenetetrahydrofolate reductase (MTHFR), cystathionine beta-synthase (CBS) with Alzheimer's disease (AD). METHODS: Plasma Hcy levels were measured by means of high voltage capillary electrophoresis with ultra-violet detection, the polymorphisms of C677T in exon 4 of MTHFR gene and 844ins68 in exon 8 of CBS gene were analyzed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) in 105 AD patients and 102 non-AD controls. All controls were excluded from cardiocerebrovascular disorders and other diseases. RESULTS: The plasma Hcy level in AD patients (16.04 +/- 3.84 micromol/L) was significantly higher than that in the controls (11.94 +/- 3.87 micromol/L, P < 0.001). There were no significant differences of the genotype and allele frequencies of MTHFR C677T mutation and CBS 844ins68 mutation between the patients and controls. However, the T allele of MTHFR gene was found to relate with the plasma Hcy level increase in all subjects. CONCLUSION: The elevated plasma Hcy level in AD patients is probably involved in the pathogenesis of AD, which may be due to the environmental factor rather than genetic factors of the mutations of MTHFR and CBS.

Aged↗
PubMed2004

Impact of incident vertebral fractures on health related quality of life (HRQOL) in postmenopausal women with prevalent vertebral fractures.

Vertebral fractures are a common complication of osteoporosis and may cause a decrease of health-related quality of life (HRQOL). This study was designed to determine the impact of incident vertebral fractures on HRQOL. The Multiple Outcomes of Raloxifene Evaluation (MORE), a multicenter, randomized, double blind trial, in which women were taking raloxifene or placebo. This study was done in European centers only in a subset of 361 women from seven European countries, all with prevalent vertebral fractures. A specific questionnaire for osteoporosis developed by the International Osteoporosis Foundation was used for assessment at baseline, 1, 2 and 3 years. This questionnaire, Qualeffo, contains 41 questions in the domains pain, physical function, social function, general health perception and mental function. Domain and total scores are expressed on a 100-point scale with 0 corresponding to the best HRQOL. Standardized lateral spinal radiographs were made at baseline, 2 and 3 years and evaluated in a central facility. Sixty-seven patients sustained a fracture in a vertebra that was not fractured at baseline (incident vertebral fractures). Twenty of these were accompanied by signs and symptoms necessitating immediate doctor's attention (clinical vertebral fractures) and 47 vertebral fractures were only diagnosed on radiographs (subclinical vertebral fractures). Incident vertebral fractures (clinical and subclinical) were associated with an increase of back pain (mean score change 6.4; 95% CI 2.1-10.7), deterioration of physical function (mean score change 2.4; 95% CI 0.1-4.8), and worse general health perception (mean score change 3.8; 95% CI 0.1-7.5). Score changes for patients with subclinical vertebral fractures were intermediate between those for patients with clinical vertebral fractures and patients without incident vertebral fracture. Clinical and subclinical incident vertebral fractures both have an adverse impact on HRQOL.

Aged↗
PubMed2004

[Pediatric renal transplantation: clinical analysis of 23 cases].

OBJECTIVE: To study the clinical characters and the therapeutic experience of pediatric kidney transplantation. METHODS: Clinical data of 23 pediatric renal transplant recipients (less than 18 years, 14 boys, 9 girls) were analyzed. Recipients were 11 - 17 (mean 15.4 +/- 1.0 years) years old at transplantation. The kidneys were transplanted en bloc extraperitoneally into the recipient's iliac fossa, with the donor renal vein anastomosed to the recipient's external iliac vein. Among 23 transplant procedures, the donor renal artery was anastomosed to the external iliac artery in 14 cases, to the internal iliac artery in 4 cases and to the common iliac artery in 3. The other two allografts were unusual. All the patients were treated with cyclosporine or tacrolimus based immunosuppression, including steroid and azathioprine or mycophenolate mofetil. The initial dose of cyclosporine was 6 - 7 mg per kilogram of body weight per day and that of tacrolimus was 0.15 - 0.20 mg per kilogram of body weight per day. The data of the recovery of renal function, rejection episodes, incidences of side effect and related complication were analyzed respectively. RESULTS: The transplantation operations were performed uneventful in all the 23 recipients. There were no graft losses for technical reasons. The single graft failure was the result from bad compliance. The renal function was improved 5.5 days in average after transplantation in 22 cases. Main complications were arterial hypertension (57%), pulmonary infection (13%), drug-induced hepatic injury (13%) and bone marrow suppression (13%). Acute rejection occurred in 4 persons 1 year post-operatively (17%). The body weight of the recipients increased 2.3 kg in average and height increased 1.0 cm after the first post-operative year. The mean duration for follow-up was 42 month. One-year patient/graft survival rate was 100%/96% and three-year patient/graft survival rate was 90%/80%. CONCLUSION: Kidney transplantation is the preferred treatment for end stage renal failure in children patient. The well procedure, reasonable immunosuppressive regime, prevention and prompt therapy of complication are the keys to get satisfactory survival rate of human/kidney.

Adolescent↗
PubMed2004

Total body skeletal muscle and adipose tissue volumes: estimation from a single abdominal cross-sectional image.

A single abdominal cross-sectional computerized axial tomography and magnetic resonance image is often obtained in studies examining adipose tissue (AT) distribution. An abdominal image might also provide additional useful information on total body skeletal muscle (SM) and AT volumes with related physiological insights. We therefore investigated the relationships between abdominal SM and AT areas from single images and total body component volumes in a large and diverse sample of healthy adult subjects. Total body SM and AT volumes were derived by whole body multislice magnetic resonance imaging in 123 men [age (mean +/- SD) of 41.6 +/- 15.8 yr; body mass index of 25.9 +/- 3.4 kg/m(2)] and 205 women (age of 47.8 +/- 18.7 yr; body mass index of 26.7 +/- 5.6 kg/m(2)). Single abdominal SM and AT slice areas were highly correlated with total body SM (r = 0.71-0.92; r = 0.90 at L(4)-L(5) intervertebral space) and AT (r = 0.84-0.96; r = 0.94 at L(4)-L(5) intervertebral space) volumes, respectively. R(2) increased by only 5.7-6.1% for SM and 2.7-4.4% for AT with the inclusion of subject sex, age, ethnicity, scanning position, body mass index, and waist circumference in the model. The developed SM and AT models were validated in an additional 49 subjects. To achieve equivalent power to a study measuring total body SM or AT volumes, a study using a single abdominal image would require 17-24% more subjects for SM and 6-12% more subjects for AT. Measurement of a single abdominal image can thus provide estimates of total body SM and AT for group studies of healthy adults.

Abdomen↗
PubMed2004

Three-compartment model: critical evaluation based on neutron activation analysis.

There is renewed interest in Siri's classic three-compartment (3C) body composition model, requiring body volume (BV) and total body water (TBW) estimates, because dual-energy X-ray absorptiometry (DEXA) and in vivo neutron activation (IVNA) systems cannot accommodate subjects with severe obesity. However, the 3C model assumption of a constant ratio (alpha) of mineral (M) to total body protein (TBPro) and related residual mass density (D(RES)) based on cadaver analyses might not be valid across groups differing in sex, race, age, and weight. The aim of this study was to derive new 3C model coefficients in vivo and to compare these estimates to those derived by Siri. Healthy adults (n = 323) were evaluated with IVNA and DEXA and the measured components used to derive alpha and D(RES). For all subjects combined, values of alpha and D(RES) (means +/- SD, 0.351 +/- 0.043; 1.565 +/- 0.023 kg/l) were similar to Siri's proposed values of 0.35 and 1.565 kg/l, respectively. However, alpha and D(RES) varied significantly as a function of sex, race, weight, and age. Expected errors in percent body fat arising by application of Siri's model were illustrated in a second group of 264 adults, including some whose size exceeded DEXA limits but whose BV and TBW had been measured by hydrodensitometry and (2)H(2)O dilution, respectively. Extrapolation of predictions by newly developed models to very high weights allows percent fat error estimation when Siri's model is applied in morbidly obese subjects. The present study results provide a critical evaluation of potential errors in the classic 3C model and present new formulas for use in selected populations.

Absorptiometry, Photon↗
PubMed2004

Intermuscular adipose tissue-free skeletal muscle mass: estimation by dual-energy X-ray absorptiometry in adults.

Skeletal muscle (SM) is a large and physiologically important compartment. Adipose tissue is found interspersed between and within SM groups and is referred to as intermuscular adipose tissue (IMAT). The study objective was to develop prediction models linking appendicular lean soft tissue (ALST) estimates by dual-energy X-ray absorptiometry (DXA) with whole body IMAT-free SM quantified by magnetic resonance imaging. ALST and total-body IMAT-free SM were evaluated in 270 healthy adults [body mass index (BMI) of <35 kg/m(2)]. The SM prediction models were then validated by the leave-one-out method and by application in a new group of subjects who varied in SM mass [anorexia nervosa (AN), n = 23; recreational athletes, n = 16; patients with acromegaly, n = 7]. ALST alone was highly correlated with whole body IMAT-free SM [model 1: R(2) = 0.96, standard error (SE) = 1.46 kg, P < 0.001]; age (model 2: R(2) = 0.97, SE = 1.38 kg, P < 0.001) and sex and race (model 3: R(2) = 0.97, SE = 1.06 kg, both P < 0.001) added significantly to the prediction models. All three models validated in the athletes and patients with acromegaly but significantly (P < 0.01-0.001) over-predicted SM in the AN group as a whole. However, model 1 was validated in AN patients with BMIs in the model-development group range (n = 11; BMI of >16 kg/m(2)) but not in those with a BMI of <16 kg/m(2) (n = 12). The DXA-based models are accurate for predicting IMAT-free SM in selected populations and thus provide a new opportunity for quantifying SM in physiological and epidemiological investigations.

Absorptiometry, Photon↗
PubMed2004

No existence of translocus balancer to coordinate the expression and regulation of human hemoglobin genes in transgenic mice study.

All mammals use hemoglobin (Hb) to transport oxygen. Each Hb molecule is a tetramer of two pairs of unlike globin polypeptide chains. Equal amount of subunit globin chains derived from the corresponding alpha- and beta-like genes can always result during development though the two separate gene clusters are located on two different chromosomes and spatially transcribed within different nuclear domains. Disturbance of this balance will result in degradation or precipitation of the excessive globin chains, which is the character of various thalassemic syndromes. In previous studies, we had established two kinds of bacterial artificial chromosome (BAC) mediated transgenic mouse models, which contain respectively the entire human alpha- and beta-globin cluster. Here, we investigated the regulatory relationship between the two clusters by interbreeding these two kinds of transgenic mice. The levels of human alpha- and beta-mRNA in the various hybrid lines reflect the levels in the original transgenic lines that contain either the alpha- or beta-globin cluster alone. The results suggested that there is no apparent cross talk or regulatory interaction between the two human globin clusters in transgenic mice.

Animals↗
PubMed2004

Fibroblast responses to cyclic mechanical stretching depend on cell orientation to the stretching direction.

Fibroblasts in intact tendons align with stretching direction, but they tend to orient randomly in healing tendons. Therefore, a question arises: Do fibroblast responses to mechanical stretching depend on their orientation? To address this question, human patellar tendon fibroblasts were grown in custom-made silicone dishes that possess microgrooved culture surfaces. The direction of the microgrooves was either parallel or normal to the direction of cyclic uniaxial stretching. Fibroblasts grown in these microgrooves had a polar morphology and oriented along the direction of the microgrooves regardless of the stretching conditions. Tendon fibroblasts expressed higher levels of alpha-smooth muscle actin when they were oriented parallel to the stretching direction than when they were oriented normal to the stretching direction. Also, cyclic stretching of the fibroblasts perpendicular to their orientation induced a higher activity level of secretory phospholipase A(2) compared with stretching of the cells parallel to their orientation. Thus, these results show that fibroblast responses to mechanical stretching depend on cell orientation to the stretching direction.

Actins↗
PubMed2004

Integrated analysis examining first-dose success, success by dose, and maintenance of success among men taking tadalafil for erectile dysfunction.

OBJECTIVES: To examine, in a post-hoc, integrated analysis, the first-dose success, cumulative success by dose, and maintenance of success among men taking tadalafil. Early treatment success is important to men with erectile dysfunction. METHODS: In five double-blind, placebo-controlled, 12-week studies, men were randomized to placebo (n = 308), tadalafil 10 mg (n = 321), or tadalafil 20 mg (n = 258) as a fixed dose. The Sexual Encounter Profile (SEP) diary questions assessed success from three perspectives: (a) first-dose success; (b) cumulative proportion of men with first success by dose; and (c) maintenance of success among men with first-dose success. RESULTS: With the first dose, significantly greater proportions of men taking tadalafil 10 and 20 mg versus placebo achieved successful erection (SEP-Q1: 85% and 90% versus 66%, respectively), successful penetration (SEP-Q2: 74% and 79% versus 47%, respectively), successful intercourse (SEP-Q3: 56% and 67% versus 31%, respectively), and were satisfied overall with their sexual experience (SEP-Q5: 36% and 47% versus 15%, respectively; all P <0.001). The proportion of men achieving first success increased with continued dosing, reaching a plateau between doses 4 and 8 at approximately 95% (SEP-Q2), 90% (SEP-Q3), and 81% (SEP-Q5). For men with first-dose success, the subsequent success rate during the 12-week period was significantly greater for men taking tadalafil 10 and 20 mg versus placebo (all P <0.001; SEP-Q2: 85% and 91% versus 75%; and SEP-Q3: 81% and 88% versus 64%, respectively). CONCLUSIONS: Most men taking tadalafil achieved successful erection, penetration, and intercourse after one dose and maintained the success over time. Because success increased with continued use, men who do not respond initially should continue treatment to increase the likelihood of treatment success.

Adult↗
PubMed2004

Cloning and over-expression of an alkaline protease from Bacillus licheniformis.

The alkaline protease gene, apr, from Bacillus licheniformis 2709 was cloned into a Bacillus shuttle expression vector, pHL, to yield the recombinant plasmid pHL-apr. The pHL-apr was expressed in Bacillus subtilis WB600, yielding a high expression strain BW-016. The amount of alkaline protease produced in the recombinant increased by 65% relative to the original strain. SDS-PAGE analysis indicated a Mr of 30.5 kDa. The amino acid sequence deduced from the DNA sequence analysis revealed a 98% identity to that of Bacillus licheniformis 6816.

Amino Acid Sequence↗