Biomedical subjects

Yu Chen

Publications and source records attributed to Yu Chen.

At least 145 records · Page 8Linked to original sources

PubMed2005

Stem cell therapy in the aging hearts of Fisher 344 rats: synergistic effects on myogenesis and angiogenesis.

OBJECTIVE: Advanced age is a major risk factor for ventricular dysfunction and reduction of cardiac reserve. Finding novel approaches to prevent and attenuate heart dysfunction associated with advanced age is a major therapeutic challenge. The present study was designed to test whether engrafted embryonic stem cells could improve myocardial function in aging hearts. METHODS: Cultured mouse embryonic stem cells used for cell therapy were transfected with green fluorescent protein. Aging rats in the cell-treated group received intramyocardial injection of embryonic stem cells. Hemodynamic measurement, myocyte counting, and evaluation of blood flow were performed 6 weeks after cell transplantation. RESULTS: Embryonic stem cell therapy partially improved cardiac reserve, as reflected by the in vivo response to isoproterenol (INN: isoprenaline) stimulation in aging hearts 6 weeks after cell implantation. The functional benefits from engrafted embryonic stem cells were associated with increased myocyte numbers and enhanced left ventricular blood perfusion in the aging heart. The characteristic phenotype of engrafted embryonic stem cells was identified in the transplanted heart on the basis of green fluorescent protein-positive spots that were further demonstrated to differentiate into cardiac tissue with positive staining for cardiac alpha-myosin heavy chain. CONCLUSIONS: Regenerating cardiomyocytes and increasing regional blood perfusion in the aging heart after embryonic stem cell transplantation synergistically resulted in improvement of cardiac function. Embryonic stem cell transplantation might hold significant clinical potential in attenuating the progressive decrease of cardiac function associated with advanced aging.

Aging↗

PubMed2005

Therapeutic options for proximal ureter stone: extracorporeal shock wave lithotripsy versus semirigid ureterorenoscope with holmium:yttrium-aluminum-garnet laser lithotripsy.

OBJECTIVES: To compare the safety and cost-effectiveness of ureterorenoscopic holmium:yttrium-aluminum-garnet (YAG) laser lithotripsy (URSL) with extracorporeal shock wave lithotripsy (ESWL) for proximal ureteral stones. METHODS: This investigation assessed 220 patients with upper ureteral stones. Those in the ESWL group were treated on an outpatient basis using the Medispec Econolith 2000 (Medispec, Germantown, MD) under intravenous sedation. URSL was performed with a 6/7.5F semirigid tapered ureterorenoscope and holmium:YAG laser under spinal anesthesia on an inpatient basis. A successful outcome was defined as the patient being stone free on radiography 1 month after treatment. The stone size, success rate, postoperative complications, and cost were evaluated in each group. RESULTS: A total of 220 patients were enrolled in this study. Hematuria and flank pain were the most common complaints in each group. The mean stone burden +/- SD was 58.7 +/- 3.1 mm2 in the ESWL group and 108.4 +/- 10.0 mm2 in the URSL group (P = 0.000). The accessibility of the semirigid ureterorenoscope for upper ureteral stones was 98.1% (101 of 103), and the stone-free rate achieved after one treatment was 83.2% (84 of 101). The initial stone-free rate of in situ ESWL was 63.9% (76 of 119). Significantly, the initial stone-free rate of the URSL group was superior to that of the ESWL group (P = 0.001). The average cost in the URSL group appeared to be lower than that in the ESWL group (P = 0.000). CONCLUSIONS: The results of this study have demonstrated that URSL achieved excellent results for upper ureter calculi. In terms of cost and effectiveness, this procedure should be the first-line therapy for proximal ureter stones.

Costs and Cost Analysis↗

PubMed2005

Effective gene-virotherapy for complete eradication of tumor mediated by the combination of hTRAIL (TNFSF10) and plasminogen k5.

Virotherapy with oncolytic viruses is a highly promising approach for cancer therapy. To improve further the therapeutic effect of oncolytic viruses, therapeutic genes have been incorporated into these types of vectors. In this study, we have inserted hTRAIL (approved gene symbol TNFSF10) into the ZD55 vector, which was based on deletion of the adenoviral E1B 55-kDa gene and could replicate in and lyse p53-deficient tumors. Our data shows that infection of colorectal carcinoma cells with ZD55-hTRAIL resulted in tumor cell death that was much greater than that induced by ZD55 vector or replication-defective adenovirus expressing hTRAIL. In contrast to these, ZD55-hTRAIL did not induce any cytopathic effect in normal cells. Treatment of established tumor with ZD55-hTRAIL resulted in dramatic inhibition of tumor growth in an animal model of colorectal carcinoma. However, when the established tumors were treated by coadministration of ZD55-hTRAIL and Ad-k5, we observed complete eradication of the established tumors in all animals treated with the combined therapy. This strong anti-tumor activity was due to the fact that two genes may act with compensative (or synergic) effect through different mechanisms to kill tumors. Therefore, targeting dual gene-virotherapy may be one of the best strategies for cancer therapy if two suitable genes are chosen.

Adenoviridae↗

PubMed2005

Axially modified gallium phthalocyanines and naphthalocyanines for optical limiting.

Phthalocyanines (Pcs) offer a high architectural flexibility in structure, which facilitates the tailoring of their physical, optoelectronic and chemical parameters over a very broad range. This tutorial review describes the recent advances in the synthesis of soluble axially substituted or bridged gallium phthalo- and naphthalocyanine compounds, and their photophysical and nonlinear optical properties. The exploitation of the chemical reactivity of the Ga-Cl bond can allow the preparation of a series of highly soluble axially substituted and bridged Pc complexes. Axial substituents in Pcs influence favourably nonlinear optical absorption for the presence of a dipole moment perpendicular to the macrocycle in the axially substituted phthalocyanines. All Z-scans performed exhibit a decrease of transmittance about the focus typical of an induced positive nonlinear absorption of incident light. Substitution and dimerization of the phthalocyanine monomer resulted in significant reductions in the saturation energy density of the material displaying clear evidence of the usefulness of structurally modifying the gallium phthalocyanine unit. Similar to indium phthalocyanines, gallium phthalocyanines are also among the most promising materials that have been investigated as limiters of intense light and the current series presents a selection of structural modifications useful for varying their nonlinear optical properties.

Journal Article↗

PubMed2005

Short communication: HIV type 1 phenotype, tropism, and sequence patterns: association and preference.

In this study, the relationship between biological phenotypes, coreceptor usages, and sequence patterns of V1V2 or V3 regions on HIV-1 envelope gp 120 was carefully analyzed based on the existing isolates in the Los Alamos National Laboratory sequence database. Obviously, SI/NSI phenotypes were closely linked to the capability of HIV-1 to use coreceptor CXCR4, but not CCR5. Moreover, compared to NSI or R5 isolates, SI or X4 HIV-1 isolates significantly prefer higher net charges and the loss of the N-linked glycosylation site in the V3 loop, but they show no preference in either net charge or N-linked glycosylation of the V1V2 region. In addition, no significant relationship between V1V2 length and virus tropism or phenotypes was observed.

Glycosylation↗

PubMed2005

A randomized, double-blind placebo-controlled trial evaluating the effects of vitamin E and selenium on arsenic-induced skin lesions in Bangladesh.

OBJECTIVE: We sought to determine whether supplementation of vitamin E (alpha-tocopherol), selenium (L-selenomethionine), or their combination improves arsenical skin lesions. METHODS: A 2 x 2 randomized, placebo-controlled, double-blind trial among 121 men and women chronically exposed to arsenic in drinking water was conducted in rural Bangladesh. Participants were randomized to one of four treatment arms: vitamin E, selenium, vitamin E and selenium (combination), or placebo and were treated for 6 months. RESULTS: At baseline, the average skin lesion scores were 2.23, 2.26, and 2.63 and at follow-up, the average skin lesion scores went down to 2.00, 2.06, and 2.47 in those receiving vitamin E, selenium, and the combination, respectively. CONCLUSIONS: Supplementation with vitamin E and selenium, either alone or in combination, slightly improved skin lesion status, although the improvement was not statistically significant.

Administration, Oral↗

PubMed2005

Inflammatory bowel disease in patients with celiac disease.

BACKGROUND: Several case reports and series report an association between celiac disease and inflammatory bowel disease (IBD); however, there is no current data assessing this association. We therefore studied the occurrence of these conditions in a cohort of patients with celiac disease seen at a referral center. METHODS: A database of patients with celiac disease seen between 1981 and 2002 was analyzed. Only biopsy-proven adults were included. Patients who had endoscopic and pathologic evidence of IBD were identified, and their pathology was reviewed. Age- and sex-adjusted prevalence rate ratios were determined by comparing results with population-based prevalence data. RESULTS: Among 455 patients with celiac disease, IBD was identified in 10 (5 had ulcerative colitis and 5 had Crohn's disease). This represented an age- and sex-adjusted prevalence rate ratio for ulcerative colitis of 3.56 (95% confidence interval, 1.48-8.56) and for Crohn's disease of 8.49 (95% confidence interval, 3.53-20.42). CONCLUSION: Within our cohort of patients with celiac disease, IBD was significantly more common than in the general population.

Adult↗

PubMed2005

Diffuse panbronchiolitis in China.

OBJECTIVE: Diffuse panbronchiolitis (DPB) is a progressive inflammatory disease, well recognized in Japan, that is characterized by chronic sinusitis and obstructive small airway disease. A total of 40 patients with DPB in mainland China were reviewed in order to describe the epidemiology of DPB in China and to compare their clinical characteristics with those of cases reported in Japan. METHODOLOGY: A systematic search was conducted of the Chinese language literature published in mainland China from 1996 to 2003. The 40 subjects who fulfilled the diagnostic criteria for DPB were retrospectively analysed for clinical, physiological, radiological, and pathological features and their geographic distribution. RESULTS: The 40 patients included in this study (31 male and nine female) were distributed in 12 provinces and three other cities in China. All presented with chronic cough, sputum production, and 32 had exertional dyspnoea. All but three had a history of sinusitis. Lung function assessment showed a mixed obstructive-restrictive pattern in 30 cases. CXR revealed diffuse fine nodular shadows in all patients. Human leukocyte antigen-B54 was positive in five patients (n = 12). A total of 30 (75%) patients had been misdiagnosed prior to their diagnosis of DPB being made. CONCLUSIONS: DPB is not rare in China but its incidence is relatively low. Poor recognition and/or genetic factors may be the reason. The clinical, radiographic and histological features of Chinese patients resemble those described in Japanese patients.

Adult↗

PubMed2005

Loupe-assisted vs microsurgical technique for modified one-layer vasovasostomy: is the microsurgery really better?

OBJECTIVES: To compare the outcome of loupe-assisted, modified one-layer vasovasostomy (MOLV) and conventional microsurgical MOLV for vasectomy reversal. PATIENTS AND METHODS: We retrospectively analysed data for 74 patients who had a MOLV between 1993 and 2003; 42 had the standard microsurgical (x10-16) MOLV (group 1, mean age 40.5 years, SD 6.3, range 30-58) and 32 a loupe-assisted (x 3) MOLV (group 2, mean age 41.3 years, SD 6, range 28-64). With general anaesthesia, each operation was performed as an outpatient procedure or with hospitalization for one night after surgery. The patients' characteristics, patency rate, paternity rate, and operative duration were compared. RESULTS: The mean (SD, range) duration of obstruction was 8.1 (5.0, 0.33-25) years in group 1 and 9.2 (4.8, 0.33-27) years in group 2. The postoperative patency and pregnancy rates were 91% and 43% for group 1 and 89% and 39% for group 2. There were no complications during or after surgery in either group, but the surgery was significantly faster for group 2. CONCLUSIONS: There was no significant difference in the patency and paternity rates between loupe-assisted and microsurgical MOLV. The surgery was significantly faster with the loupe-assisted method. Because of the shorter operation duration and less expensive instruments required that should reduce the cost, the loupe-assisted MOLV should be considered as the best choice for simple vasectomy reversal.

Adult↗

PubMed2005

Protein families and RNA recognition.

This minireview series examines the structural principles underlying the biological function of RNA-binding proteins. The structural work of the last decade has elucidated the structures of essentially all the major RNA-binding protein families; it has also demonstrated how RNA recognition takes place. The ribosome structures have further integrated this knowledge into principles for the assembly of complex ribonucleoproteins. Structural and biochemical work has revealed unexpectedly that several RNA-binding proteins bind to other proteins in addition to RNA or instead of RNA. This tremendous increase in the structural knowledge has expanded not only our understanding of the RNA recognition principle, but has also provided new insight into the biological function of these proteins and has helped to design better experiments to understand their biological roles.

Animals↗

PubMed2005

Comparison of plasma exchange with different membrane pore sizes in the treatment of severe viral hepatitis.

Plasma exchange has become an effective mode of blood purification in patients suffering from liver failure. To assist in patient recovery, we compared two plasma separators to identify a plasma separator with suitable pore sizes to remove toxic substances effectively, and retain important plasma components. The study focused on severe viral hepatitis patients. Of 206 rounds of plasma exchange, 137 were completed with the PS-06 plasma separator (membrane pore size=0.2 microm) and 69 with the EC-4A plasma separator (membrane pore size=0.03 microm). The efficacy of different plasma separators was compared using survival rate, changes in liver biochemistry, immunoglobulin, and complement parameters. The survival rate of patients treated with PS-06 was 43.3% (13 of 30 patients). For patients treated with EC-4A, two patients were bridged to liver transplantation successfully, and 57.9% (11 of 19 patients) survived. In both groups, the levels of total bilirubin, prothrombin time, and bile acid declined significantly. Compared to PS-06, EC-4A could retain significantly larger amounts of immunoglobulin and complements. Our study revealed that plasma exchange implementation with membrane pore size 0.03 microm could remove adequate bilirubin and bile acid, a class of toxins bound to plasma protein in severe viral hepatitis patients, and reduce the loss of essential plasma macromolecules.

Adult↗

PubMed2005

Magnetic confinement of electron and photon radiotherapy dose: a Monte Carlo simulation with a nonuniform longitudinal magnetic field.

It recently has been shown experimentally that the focusing provided by a longitudinal nonuniform high magnetic field can significantly improve electron beam dose profiles. This could permit precise targeting of tumors near critical areas and minimize the radiation dose to surrounding healthy tissue. The experimental results together with Monte Carlo simulations suggest that the magnetic confinement of electron radiotherapy beams may provide an alternative to proton or heavy ion radiation therapy in some cases. In the present work, the external magnetic field capability of the Monte Carlo code PENELOPE was utilized by providing a subroutine that modeled the actual field produced by the solenoid magnet used in the experimental studies. The magnetic field in our simulation covered the region from the vacuum exit window to the phantom including surrounding air. In a longitudinal nonuniform magnetic field, it is observed that the electron dose can be focused in both the transverse and longitudinal directions. The measured dose profiles of the electron beam are generally reproduced in the Monte Carlo simulations to within a few percent in the region of interest provided that the geometry and the energy of the incident electron beam are accurately known. Comparisons for the photon beam dose profiles with and without the magnetic field are also made. The experimental results are qualitatively reproduced in the simulation. Our simulation shows that the excessive dose at the beam entrance is due to the magnetic field trapping and focusing scattered secondary electrons that were produced in the air by the incident photon beam. The simulations also show that the electron dose profile can be manipulated by the appropriate control of the beam energy together with the strength and displacement of the longitudinal magnetic field.

Algorithms↗

PubMed2005

Identification of novel subgenomic RNAs and noncanonical transcription initiation signals of severe acute respiratory syndrome coronavirus.

The expression of the genomic information of severe acute respiratory syndrome coronavirus (SARS CoV) involves synthesis of a nested set of subgenomic RNAs (sgRNAs) by discontinuous transcription. In SARS CoV-infected cells, 10 sgRNAs, including 2 novel ones, were identified, which were predicted to be functional in the expression of 12 open reading frames located in the 3' one-third of the genome. Surprisingly, one new sgRNA could lead to production of a truncated spike protein. Sequence analysis of the leader-body fusion sites of each sgRNA showed that the junction sequences and the corresponding transcription-regulatory sequence (TRS) are unique for each species of sgRNA and are consistent after virus passages. For the two novel sgRNAs, each used a variant of the TRS that has one nucleotide mismatch in the conserved hexanucleotide core (ACGAAC) in the TRS. Coexistence of both plus and minus strands of SARS CoV sgRNAs and evidence for derivation of the sgRNA core sequence from the body core sequence favor the model of discontinuous transcription during minus-strand synthesis. Moreover, one rare species of sgRNA has the junction sequence AAA, indicating that its transcription could result from a noncanonical transcription signal. Taken together, these results provide more insight into the molecular mechanisms of genome expression and subgenomic transcription of SARS CoV.

Animals↗

PubMed2005

Upgrading of anaerobic digestion by incorporating two different hydrolysis processes.

The purpose of this study was to increase the efficiency of anaerobic digestion of waste activated sludge (WAS). Either thermochemical or biological hydrolysis was used as a pretreatment and the effects of both were investigated and compared. Two different three-stage digestion systems showed improved performance, although thermochemical hydrolysis showed better results than biological hydrolysis in a bench-scale operation. After anaerobic digestion with thermochemical pretreatment, the total chemical oxygen demand (tCOD) reduction, volatile solid (VS) reduction, methane yield and methane biogas content were 88.9%, 77.5%, 0.52 m3/kg VS and 79.5%, respectively. These results should help in determining the best hydrolysis pretreatment process for anaerobic digestion and in improving the design and operation of the large-scale treatment of WAS by anaerobic digestion with hydrolysis systems.

Anaerobiosis↗

PubMed2005

[A discussion of standardization for prothrombin time in patients with advanced liver diseases].

OBJECTIVE: To determine which expression mode of prothrombin time (PT) might achieve PT standardization in patients with advanced liver diseases. METHODS: PT was measured with six thromboplastins with different ISI values in 16 severe chronic hepatitis patients, 50 decompensated liver cirrhosis patients and 30 patients on oral anticoagulation therapy. The results were expressed in PT (second), PTA (%), PTR and INR. RESULTS: In chronic hepatitis patients, the means of the six group's PTAs ranged from 24% to 34%, while their upper limits ranged from 47% to 61%. The means of the INRs ranged from 2.55 to 5.13, while their upper limits ranged from 4.65 to 12.77. Through one-way ANOVA of repeated measures, PPTA (0.489) was > PINR (0.120). In patients with liver cirrhosis, the means of the PTA in six groups ranged from 50% to 59%, while their upper limits ranged from 82% to 90%. The means of the INR ranged from 1.40 to 1.80, while their upper limits ranged from 1.97 to 3.69. Through one-way ANOVA of repeated measures, PPTA (0.102) was > PINR (0.01). In patients on oral coagulation therapy, the means of PTA ranged from 26% to 37%, while their upper limits ranged from 39% to 49%. The means of INR ranged from 2.35 to 2.66, while their upper limits ranged from 3.16 to 4.26. Through one-way ANOVA of repeated measures, PPTA (0.01) was less than PINR (0.102). The correlation between the results detected by Neoplastine and by other reagents were analyzed. They correlated well with each other when PTA was used as the expression mode of PT in patients with advanced liver disease. But in patients on oral anticoagulation therapy, when only the INR was used as the expression mode of PT, the correlation was well with each other. CONCLUSION: The use of INR provides inadequate standardization. Only when the PT is expressed in PTA, then it may provide a standardization mode in patients with advanced liver diseases.

Female↗

PubMed2005

[Effect of angiogenin on angiogenesis in gastric carcinoma].

BACKGROUND & OBJECTIVE: Angiogenin (ANG), an efficient angiogenesis factor, is up-regulated in human colorectal carcinoma, pancreatic carcinoma, and other tumors. But the function of ANG in tumor angiogenesis is still unknown. This study was to explore the effect of ANG on angiogenesis of gastric carcinoma. METHODS: The expressions of ANG, CD34, and Ki-67 in 68 specimens of gastric carcinoma were detected by immunohistochemistry. Microvessel density (MVD) was figured out according to the expression of CD34. The proliferation index of carcinoma cells in gastric carcinoma tissue was figured out according to the expression of Ki-67. RESULTS: Of the 68 specimens of gastric carcinoma, 19 showed strongly positive expression of ANG (group A), 3 showed negative expression of ANG (group B). MVD of group A was significantly higher than that of group B (308.4+/-25.6 vs. 196.0+/-31.3, P<0.01). Proliferation index of group A was significantly higher than that of group B (579.6+/-31.4 vs. 341.3+/-84.0, P<0.01). CONCLUSION: Protein level of ANG positively correlates with MVD of gastric carcinoma tissue, and proliferation index of carcinoma cells.

Adenocarcinoma↗

PubMed2005

Genome-scale protein function prediction in yeast Saccharomyces cerevisiae through integrating multiple sources of high-throughput data.

As we are moving into the post genome-sequencing era, various high-throughput experimental techniques have been developed to characterize biological systems at the genome scale. Discovering new biological knowledge from high-throughput biological data is a major challenge for bioinformatics today. To address this challenge, we developed a Bayesian statistical method together with Boltzmann machine and simulated annealing for protein function prediction in the yeast Saccharomyces cerevisiae through integrating various high-throughput biological data, including protein binary interactions, protein complexes and microarray gene expression profiles. In our approach, we quantified the relationship between functional similarity and high-throughput data. Based on our method, 1802 out of 2280 unannotated proteins in the yeast were assigned functions systematically. The related computer package is available upon request.

Bayes Theorem↗

PubMed2005

[The expression of matrix metalloproteinases and their tissue inhibitors in pleomorphic adenoma].

OBJECTIVE: To examine the expression of MMPs and TIMPs in pleomorphic adenoma of salivary gland and to investigate the relationship between the expression and the biological behaviour of the tumor. METHODS: Twenty-three cases of pleomorphic adenoma were divided into active type and common type according to their biological behavior. Immunohistochemistry for MMP-2, MMP-9, TIMP-1, TIMP-2 and gelatin zymography analysis were performed in these 23 cases and in 6 malignant and 6 benign salivary gland tumors. RESULTS: The immunoreactivity of MMP-2 protein and MMP-2/TIMP-1, 2 ratio were significantly higher in active pleomorphic adenoma than in common pleomorphic adenoma (P = 0.028, P = 0.009, P = 0.045). The expression of active MMP-2, proMMP-9 and active MMP-9 were significantly higher in active pleomorphic adenoma than in common pleomorphic adenoma (P = 0.034, P = 0.021, P = 0.001). There was no significant difference in expression of MMP-2, MMP-9, TIMP-1 and TIMP-2 between the salivary malignant tumor and active pleomorphic adenoma, also between the salivary benign tumor and common pleomorphic adenoma. CONCLUSIONS: The expression of MMPs and TIMPs in active pleomorphic adenoma is similar to that in salivary carcinomas, and the expression in common pleomorphic adenoma also resembled to that in salivary adenoma. The expression of MMP-2, 9 and TIMP-1, 2 is related to the biological behavior of pleomorphic adenoma of salivary gland.

Adenoma, Pleomorphic↗