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Biomedical subjects

T Wen

Publications and source records attributed to T Wen.

At least 19 recordsLinked to original sources
PubMed2006

Factors related to post-liver transplantation acute renal failure.

Acute renal failure (ARF) after liver transplantation (OLT) is a common complication with severe impact on early and late prognosis of recipients. Factors predicting its incidence have not been fully identified due to the lack of a universal standard as well as the variance of data between transplant centers. To identify factors related to post-OLT ARF, we retrospectively collected materials on 89 patients, who underwent OLT from 1999 to 2001 in our center. Factors associated with post-OLT ARF were identified using univariate logistic regression. Significant factors were then entered into a multivariate logistic regression to identify factors independently associated with post-OLT ARF. Upon univariate analysis, intraoperative volume of blood transfusion (P = .041) and duration of operation (P = .005) were significant. ARF was associated with a poor prognosis (P < .001). Only duration of operation (P = .026) was an independent factor predicting the development of ARF. In conclusion, intraoperative volume of blood transfusion and duration of operation were factors contributing to post-OLT ARF in which the duration of the operation was an independent risk factor. The incidence of post-OLT ARF greatly increased recipient mortality in the early postoperative period.

Acute Kidney Injury↗
PubMed2006

Systematic parameter screening for capillary electrophoresis monitoring of surfactants on silicon wafer surfaces by designed experiments.

The surface purity of silicon wafers is an important parameter to monitor for yield improvement of semiconductor devices in a production line. Surfactants are used to reduce the surface potential in order to facilitate the removal or cleaning of particles and metals. Traces of surfactant residues from the cleaning bath may still be present on the wafer surface after the final cleaning step. In this report, two capillary electrophoresis (CE) methods for the analysis of dodecylbenzene sulfonate (DBS) are developed for monitoring the surfactant residues in the wafer manufacturing process. One method is developed for the sensitive determination of all DBS homologues and isomers in one single peak. Another method is developed for the fingerprint analysis of the homologues and isomers of DBS. The Taguchi methodology was used as a systematic optimization tool for the DBS analysis by CE. The experiments were evaluated by calculating the signal-to-noise ratio values with four responses. The lowest detection limit for DBS was 15 microg/L at 95% confidence level. The percent recovery of surfactant was between 90% and 110%.

Journal Article↗
PubMed2003

Cloning of the KcURA3 gene and development of a transformation system for Kluyveromyces cicerisporus.

KcURA3 was cloned from Kluyveromyces cicerisporus CBS4857 by complementation of the ura3 mutation in Saccharomyces cerevisiae. KcURA3 encodes a 267-amino-acid protein with 80% sequence identity to that of S. cerevisiae. An ura3 mutant strain from K. cicerisporus CBS4857, named Y179U, was obtained by selection on 5-fluoroorotic acid plates. Sequence analysis of this mutated gene revealed that it contained a point mutation at nucleotide position +277. Two vectors, pUK1 and pUKD, bearing KcURA3 were constructed. Either the lithium acetate method or electroporation could be used to transform pUK1 and pUKD intoY179U. The transformation efficiency using electroporation was higher than that using the lithium acetate method.

Acetates↗
PubMed2001

Type of inversion problem in physics: an inverse emissivity problem.

Inversion problems have recently drawn vast amounts of attention from the physics community due to their potential widespread applications. In this Rapid Communication, a different type of inversion problem in physics is proposed: an inverse emissivity problem, which aims to determine the emissivity g(nu) by measuring only the total radiated power J(T). Like other inverse problems, this one has potential for important practical applications. An exact solution is obtained for the proposed inverse problem. A unique existence theorem and techniques for eliminating divergences are also presented. A universal function set (UFS) suggested for numerical calculations is shown to be very useful in a numerical example. The UFS makes this inversion method practical and convenient for realistic calculations.

Journal Article↗
PubMed2000

Exact solution of the specific-heat-phonon spectrum inversion from the Mobius inverse formula

The application of the Mobius inversion formula to the specific-heat-phonon spectrum inversion problem (SPI) initially appeared promising [N.X. Chen, Phys. Rev. Lett. 64, 1193 (1990); J. Maddox, Nature (London) 344, 377 (1990)]. However, no one has previously been able to obtain the exact Debye spectrum with the correct cut-off factor and frequency dependence from the Mobius formula. The main difficulty arises from the fact that the Mobius function &mgr;(n) is not completely known for large n in practice. In this paper, some exact solutions of SPI are obtained by using the Mobius inversion formula, most importantly the Debye spectrum as a special case, and the problem of the unknown Mobius function &mgr;(n) for large n is avoided. It is shown that the Mobius inversion formula can be useful for exact solutions to spectral inversion problems.

Journal Article↗
PubMed2000

[Surgery for patients with primary liver cancer: report of 1,038 patients].

OBJECTIVE: To investigate methods for enhancing safety of and improving the survival in patients with primary liver cancer (PLC). METHODS: One thousand and thirty eight patients with PLC were treated in our hospital from January 1990 to December 1998. The early period group (from January 1990 to December 1996) consisted of 731 patients [312 patients (42.7%) receiving liver resection]; the late period group (from January 1997 to December 1998) included 307 patients [217 patients (70.7%) receiving liver resection]. RESULTS: The mortality within one month after hepatectomy was 2.24% in the early group and 0.74% in the late group. The 1-, 3- and 5-year survival rates were 73.1%, 54.2%, and 34.0% respectively in patients undergoing hepatectomy in the early group and 91.1%, 63.8% and 40.2% in the late group. CONCLUSIONS: Regular follow-up of high risk patients is helpful to discover small PLC. High proportion of small PLC, progress of perioperative management, and improvement of operative techniques including hepatopetal blood occlusion of half liver or in vitro-bypass through bio-pump during hepatectomy might be important approaches to enhance the safety of surgical treatment and improve the prognosis of patients with PLC.

Adolescent↗
PubMed1999

Analysis of 4-1BB ligand (4-1BBL)-deficient mice and of mice lacking both 4-1BBL and CD28 reveals a role for 4-1BBL in skin allograft rejection and in the cytotoxic T cell response to influenza virus.

4-1BB ligand (4-1BBL) is a member of the TNF family expressed on activated APC. 4-1BBL binds to 4-1BB (CD137) on activated CD4 and CD8 T cells and in conjunction with strong signals through the TCR provides a CD28-independent costimulatory signal leading to high level IL-2 production by primary resting T cells. Here we report the immunological characterization of mice lacking 4-1BBL and of mice lacking both 4-1BBL and CD28. 4-1BBL-/- mice mount neutralizing IgM and IgG responses to vesicular stomatitis virus that are indistinguishable from those of wild-type mice. 4-1BBL-/- mice show unimpaired CTL responses to lymphocytic choriomeningitis virus (LCMV) and exhibit normal skin allograft rejection but have a weaker CTL response to influenza virus than wild-type mice. 4-1BBL-/-CD28-/- mice retain the CTL response to LCMV, respond poorly to influenza virus, and exhibit a delay in skin allograft rejection. In agreement with these in vivo results, allogeneic CTL responses of CD28-/- but not CD28+/+ T cells to 4-1BBL-expressing APC are substantially inhibited by soluble 4-1BB receptor as is the in vitro secondary response of CD28+ T cells to influenza virus peptides. TCR-transgenic CD28-/- LCMV glycoprotein-specific T cells are insensitive to the presence of 4-1BBL when a wild-type peptide is used, but the response to a weak agonist peptide is greatly augmented by the presence of 4-1BBL. These results further substantiate the idea that different immune responses vary in their dependence on costimulation and suggest a role for 4-1BBL in augmenting suboptimal CTL responses in vivo.

4-1BB Ligand↗
PubMed1999

[A clinical study on systemic inflammatory response syndrome and multiple organ dysfunction syndrome in patients with abdominal surgical emergency].

In order to analyze the development from systemic inflammatory response syndrome(SIRS) to multiple organ dysfunction syndrome (MODS) and probe the therapeutic strategies, the authors studied retrospectively the clinical data of SIRS and MODS in 1374 patients with abdominal surgical emergency. The results showed that on admission the morbidity of SIRS was 32.5%, afterwards the morbidity of MODS was 6.4%, and the mortality of the patients with SIRS was 4.8%. After 48 hours' therapy, MODS developed in 33.0% of the SIRS cases. Of all the 1374 patients, 40 developed MODS(2.9%) and 27 died (67.5%). The authors point out that the outcome of the patients with abdominal surgical emergency can be improved on condition that SIRS is early diagnosed, the cause of SIRS after 48 hours of therapy is well defined, and the body inflammatory response is properly regulated.

Abdomen, Acute↗
PubMed1999

[Construction of thermotolerant ethanol-producing yeast by protoplast fusion].

Protoplast fusion between Saccharomyces cerevisiae A001 and Kluyveromyces Y034 has been studied. A001 is a high alcohol yield yeast and can ferment maltose into ethanol, but can not grow at 45 degrees C. However, Y034 can grow above 45 degrees C but has a lower alcohol yield and can not ferment maltose. We obtained the fusants which were tested in several aspects such as cell morphology, physiological and biochemical feature, isozyme patterns analysis, alcohol fermentation at high temperature(45 degrees C) and so on. The fusant AY023 with the final ethanol concentration of 7.4% has been selected, which is thermotolerant yeast with the highest alcohol yield at 45 degrees C until now.

Cell Fusion↗
PubMed1999

[Safety analysis of dust mite allergen for diagnosis and immunotherapy of asthma and rhinitis].

AIM: To make a retrieval investigation of safety in using Dermatophagoides farinae extract in diagnosis and immunotherapy with patients of asthma and rhinitis. METHODS: A questionnaire evaluation of the safety use of D. farinae extract (SMU-Df) during diagnosis and immunotherapy of patients from 1974 to 1995 was carried out. RESULTS: A total of 8,46,342 injections were statistically analysed, among whom 142 systemic adverse reactions occurred involving urticaria 0.82@10000, severe attack of asthma 0.77@10000, anaphylactic shock 0.07@10000 (CL = 1.4-12.0/million), and angioedma 0.02@10000. The time of onset of systemic reactions of immediate type was < 30 min in 32 cases-times, and 1 h and 2 h in 6 cases-times; the time to onset of late response type was 3 h-48 h in 23 cases-times with highest incidence of severe asthmatic attacks. The systemic reactions occurred in 18 subjects during skin test, in 96 cases-times during increasing dose phase, and in 14 cases-times during. Among them 6 cases were of anaphylactic shock, and none of it after emergency treatment. The major cause of manifestation of systemic reactions for 41 cases after immunotherapy with SMU-Df extract was due to over dosage errors. CONCLUSION: The application of SMU-Df extract in skin test and immunotherapy of asthma and rhinitis sensitive to mite for the past 22 years in this country indicated that the efficacy and safety have been high.

Allergens↗
PubMed1998

Interferon gamma impairs the ability of monocyte-derived dendritic cells to present tumour-specific and allo-specific antigens and reduces their expression of CD1A, CD80 AND CD4.

Dendritic cells (DC), the most potent antigen-presenting cells found to date, can be generated from the adherent fraction of peripheral blood mononuclear cells (PBMC) by culture with granulocyte-macrophage colony-stimulating factor (GM-CSF) and IL-4. When interferon gamma (IFN-gamma) was added to the culture medium, the expression of CD1a, CD4 and CD80 markers were significantly reduced, while that of HLA-A, B, C, MHC II (MHC-DR), CD11a and CD54 were increased. T cell proliferation analysis showed that the DC derived from monocytes cultured with GM-CSF, IL-4 and IFN-gamma only induced weak responses in both activated and naive allogenic CD4(+) and CD8(+) T cells when compared to the reaction elicited by DC cultured without IFN-gamma. Furthermore, the DC derived from cultures with IFN-gamma, loaded with an immunogenic peptide derived from the HER2/neu protein [HER2 (9466)], only induced low levels of TNF release and weak proliferative responses in a specific cytotoxic CD8(+) T lymphocyte clone. Therefore, our results indicate that IFN-gamma negatively influences the differentiation and function of monocyte-derived DC by affecting the expression of surface molecules involved in their antigen-presenting function. This supports the general hypothesis that there exists a feedback immune regulatory mechanism between T cells and monocytes/DC.

Antigens, CD↗
PubMed1998

Requirement of the CD8+ or CD4+ T lymphocyte subsets for the rejection of lymphoma and fibrosarcoma grafts studied in gene knockout hosts.

Rejections of the retrovirus induced lymphomas (ALC and RBL-5) and the methylcholanthrene (MCA) induced fibrosarcoma (MC57X) grafts were tested in syngeneic CD8 and CD4 single and double knockout C57BL/6 mice. The results with the lymphomas showed that the CD8+ T cell deficiency prevented the development of rejection response induced by immunization. Deficiency of the CD4+ T subset abrogated also the rejection of ALC. Immunity against the fibrosarcoma cells developed in both type of single knockout mice, but not in the ones which lacked both CD4+ and CD8+ T cells. Thus CD8+ T cells were required for rejection of the lymphoma cells, while the CD4+ T cells only mediated a weak response. In absence of CD8+ T cells, CD4+ T cells were sufficient to reject the fibrosarcoma cells.

Animals↗
PubMed1998

[Cellular apoptosis, proliferation and bcl-2 Bax expression in colorectal carcinoma and their association with tumor prognosis].

OBJECTIVE: To investigate the relationship between cellular apoptosis, proliferation and bcl-2/bax expression in the tissue of colorectal carcinoma and biological behavior of the tumor. METHOD: The apoptotic cells index (AI) in situ were identified by the terminal deoxynucleotidyl transfer-mediated dUTP-biotin nick end labeling (TUNEL) and immunohistologic staining for Ki-67 proliferation index (KI), bcl-2/bax protein expression was performed on archival material from 77 adenocarcinomas. RESULT: The mean AI and KI were 5.3/45.4 in early stage cancer, 5.6/48.7 in non-metastatic cancer, 6.6/55.3 in advanced cancer and 8.9/60.1 in cancer with distant metastasis respectively. There was a positive relationship between the AI and KI in each specimen. bcl-2 and bax was expressed as 54.5%, 74% in carcinoma and highly differentiated carcinoma. In the univariate analysis, significantly longer survival time was observed in the subgroup of bcl-2 positive carcinoma with low AI. In the multivariate analysis, tumor stage, tumor type, KI, and bcl-2 expression were independent risk factors for prognosis. CONCLUSION: The data indicate that abnormally exchanged AI/KI, bcl-2/bax expression appears to be an event associated with tumor progression and apoptosis might also reflect the proliferative activity of human colorectal carcinoma.

Apoptosis↗
PubMed1997

CD28 is not required for rejection of unmanipulated syngeneic and autologous tumors.

To gain a better understanding of the requirement of CD28 co-stimulation in different types of T cell-dependent tumor rejection responses, we performed a series of syngeneic and autologous tumor rejection experiments on CD28 knockout mice. In a preimmunization-challenge model, virally-induced ALC lymphoma and methylcholanthrene-induced MC57X fibrosarcoma transplants were rejected similarly by syngeneic CD28 knockout and immunocompetent controls. ALC-specific cytotoxic T lymphocytes (CTL) and MC57X-specific tumor necrosis factor (TNF) release were induced in CD28 knockouts, although at a reduced level in the latter case. Secondly, the spontaneous regression of Moloney murine sarcoma virus (MMSV)-induced primary tumors in the autologous hosts occurred equally in CD28 knockouts and in immunocompetent control mice. A comparable virus-specific CTL response was generated in both, as revealed in cytolytic assays against RBL-5 targets. Thirdly, the spontaneous rejection of the B7-transfected EL-4 lymphoma by immunocompetent hosts was abrogated in CD28 knockout mice, since more than 82% CD28 knockouts developed tumors after inoculation with B7-transfected EL-4 cells. Our results therefore show that CD28 co-stimulatory molecules are not required for the rejection of unmanipulated syngeneic tumors in hyperimmunized hosts and the regression of MMSV-induced sarcoma in autochthonous hosts.

Animals↗
PubMed1997

Two-dimensional echocardiography and Doppler ultrasound in managing obstetric patients.

OBJECTIVE: To test the usefulness of ultrasound-derived measurements of intracardiac filling pressures and cardiac performance in the noninvasive management of obstetric patients with an indication for hemodynamic monitoring. METHODS: We included patients with oliguria unresponsive to crystalloid boluses, with hypertension unresponsive to hydralazine, and at high risk for pulmonary edema who were determined to be candidates for invasive monitoring. They were first studied with two-dimensional echocardiography and Doppler ultrasound using a technique previously validated at our institution. Cardiac dimensions, filling pressures, and function were assessed at the bedside. Subsequently, management decisions were made based on these findings. RESULTS: Fourteen patients were studied. Two received a pulmonary artery catheter after noninvasive evaluation indicated a need for continuous monitoring. The 12 patients managed without the need for a pulmonary artery catheter included women with intractable hypertension (one patient), pulmonary edema (two patients), complex cardiac lesions (two patients), oliguria (five patients), intractable hypertension and oliguria (one patient), and unexplained dyspnea with peripheral arterial oxygen desaturation (one patient). Although some patients received as much as 8 L of crystalloid, none developed pulmonary edema or left ventricular failure. In all 12 cases, the ultrasound monitoring allowed successful noninvasive management of the patient. CONCLUSION: This pilot study suggests that two-dimensional echocardiography and Doppler examination may be an effective alternative to invasive monitoring in the management of selected pregnant patients.

Adult↗
PubMed1997

[Evaluation of oral glucose tolerance test in the assessment of reserved function of liver for patients with hepatocellular carcinoma].

The aim of this study was to evaluate oral glucose tolerance test(OGTT)in the assessment of reserved function of liver for predicting the tolerability of patients to hepatectomy and hence provided a criteria for selecting the candidates for undergoing hepatectomy, since the majority of hepatocellular carcinoma (HCC) patients were associated with posthepatitis cirrhosis. The preoperative and postoperative OGTT and liver biopsy for pathological investigation were carried out in 62 cases of hepatecomized patients and 49 cases of unresected patients for comparison. The results revealed that the patients whose preoperative OGTT curve was of P type recovered uneventfully after hepatectomy, but those whose curve was of L type of tolerated poorly to hepatectomy and were liable to postoperative hepatic failure and complications. The severity of cirrbosis in those poor risk patients fell to C III or C IV histological degree. 29 patients with intermediate feature of OGTT curve between P type and L type, i.e. I type underwent regional vascular occlusion at hepatic hilus as hepatectomy, and infusion of Danshen extract solution before vascular occlusion to prevent hepatocytes from reperfusion injury. Of them, 20 recovered uneventfully, 8 suffered from complications such as ascites and/or juandice, and 1 died within 1 month after operation. The followup study showed that the survival time of patients with P type OGTT curve was longer than that of I type, and the latter was longer than that of L type. The pattern of OGTT curve could change from preoperative P type to postoperative L type, depending on the severity of vascular interruption of liver and the ischemic injury to hepatocytic mass in operation.

Adolescent↗
PubMed1996

Polyoma tumor development in neonatally polyoma-virus-infected CD4-/- and CD8-/- single knockout and CD4-/-8-/- double knockout mice.

CD4-/- or CD8-/- single knockout as well as CD4-/-8-/- double knockout mice were infected with polyoma virus as newborns or 1 week after birth. The animals were followed for tumor development and virus persistence. Double knockout mice developed tumors at a higher incidence (29%) than either the CD8-/- or CD4-/- single knockout mice (11% and 2%, respectively). Persistence of polyoma virus was examined by PCR in one third of all animals included in the study. Seven of the 17 CD4-/-8-/- double knockout mice gave positive evidence of virus persistence up to 6 months p.i. where virus DNA was present in most organs. Corresponding tests in single knockout mice gave positive results of persistent viral DNA in 2 of the 19 CD8-/-and 2 of the 7 CD4-/-mice. In the single knockout mice polyoma DNA could only be detected in a more limited variety of organs compared to the double knockouts.

Animals↗