Search PubMed⌕ Search

Biomedical subjects

G H Chen

Publications and source records attributed to G H Chen.

At least 55 records · Page 3Linked to original sources
PubMed1999

Anti-TNF antibody modulates cytokine and MHC expression in cardiac allografts.

Tumor necrosis factor-alpha (TNF) is a multifunctional cytokine evoked in response to alloantigen stimulation and may be involved in lymphocyte activation, adhesion molecule expression, and regulation of MHC class II antigens. Anti-TNF treatment prolongs cardiac allograft survival. We investigated the role of anti-TNF in the regulation of MHC class II antigens and cytokine mRNA expression of TNF, interferon-gamma (IFN), IL-2, IL-4, and IL-10 in cardiac allografts to elucidate its immunological mechanism. These in vivo studies were conducted using a rat MHC mismatch Brown-Norway to Lewis (BN to LEW) heterotopic cardiac transplant model. In control untreated rats, allografts were rejected at 6.8 +/- 0.6 days. Allograft survival was significantly prolonged to 12.7 +/- 1.4 days with anti-TNF treatment. MHC class II expression, analyzed by indirect immunofluorescence cytometry, demonstrated that MHC class II-positive cells increased by 25% in spleens of untreated allografted rats compared to naive rats, while anti-TNF-treated allografted rats had a similar percentage of MHC II cells as naives. Further, naive, untransplanted rats and both anti-TNF and untreated, transplanted rats had heart and spleens harvested on Day 5 post-transplant. Cytokine mRNA expression was determined by semiquantitative RT-PCR. In heart and spleen cells from naives, TNF mRNA expression was undetectable or very weak. However, in rejecting allografts and spleen cells from untreated recipients, TNF expression was remarkably increased, while anti-TNF attenuated this TNF expression in both heart graft and spleen cells. Furthermore, IL-2, IL-10, and IFN expression were absent in naive hearts. However, in untreated allografts IL-2, IL-10, and IFN were strongly expressed, which was markedly decreased after anti-TNF treatment. Finally, IL-4 expression was found equally in naive hearts, untreated allografts, and anti-TNF-treated allografts. These results suggest that anti-TNF antibody treatment may not only neutralize TNF activity but also play a role in altering cytokine mRNA expression and MHC class II expression.

Animals↗
PubMed1999

A kinetic model incorporating energy spilling for substrate removal in substrate-sufficient batch culture of activated sludge.

Batch assays are currently used to study the kinetic behavior of microbial growth. However, it has been shown that the outcome of batch experiments is greatly influenced by the initial ratio of substrate concentration (S(o)) to biomass concentration (Xo). Substrate-sufficient batch culture is known to have mechanisms of spilling energy that lead to significant nongrowth-associated substrate consumption, and the Monod equation is no longer appropriate. By incorporating substrate consumption associated with energy spilling into the balance of the substrate oxidation reaction, a kinetic model for the observed specific substrate consumption rate was developed for substrate-sufficient batch culture of activated sludge, and was further verified by experimental data. It was demonstrated that the specific substrate consumption rate increased with the increase of the S(o)/Xo ratio, and the majority of substrate was consumed through energy spilling at high S(o)/Xo ratios. It appears that the S(o)/Xo ratio is a key parameter in regulating metabolic pathways of microorganisms.

Bacteria, Aerobic↗
PubMed1999

Urokinase is required for T lymphocyte proliferation and activation in vitro.

We have previously demonstrated that urokinase-deficient (uPA-/-) mice do not increase lung T lymphocyte number and fail to mount protective immune responses during pulmonary Cryptococcus neoformans infection. These observations suggest a previously unconsidered role for urokinase-type plasminogen activator (uPA) in T lymphocyte-mediated immune responses. Accordingly, we sought to determine whether uPA is required for T cell receptor-mediated (TCR-mediated) lymphocyte proliferation and activation. Splenocytes from uPA-/- and uPA+/+ mice were stimulated with concanavalin A (Con A). The uPA-/- mice had diminished T cell proliferation as compared with uPA+/+ mice. Coculturing uPA-/- T cells with uPA+/+ accessory cells led to the restoration of proliferation. Similarly, T cell proliferation induced by CD3 cross-linking was diminished in uPA-/- mice as compared with uPA+/+ mice. T lymphocyte activation, defined as the induced expression of antigens and the elaboration of cytokines, was determined. The expression of CD69 and that of CD49d were diminished in response to Con A stimulation in uPA-/- mice as compared with uPA+/+ mice. The elaboration of cytokines in response to Con A was also altered in the uPA-/- mice. The production of the Th1 cytokines interferon-gamma and interleukin-12 was diminished in uPA-/- mice as compared with uPA+/+ mice. The uPA-/- mice produced increased amounts of interleukin-10, a Th2 cytokine. We conclude that the lack of uPA results in impaired T cell activation and proliferation in response to TCR-mediated signaling and the expression of a less Th1-polarized profile of cytokines. These findings suggest that the inability of uPA-/- mice to combat Cryptococcus neoformans infection may be caused by the impairment of T lymphocyte immune responses in the absence of uPA.

Animals↗
PubMed1999

Interaction between Helicobacter pylori and non-steroidal anti-inflammatory drugs in peptic ulcer bleeding.

BACKGROUND: Helicobacter pylori and non-steroidal anti-inflammatory drugs (NSAIDs) are the two primary causes of peptic ulcer disease. How H. pylori and NSAIDs interact and influence the development of ulcer bleeding is still not clear. METHODS: A hospital-based, age- and sex-matched case-control study was conducted. Multivariate and stratified analyses were performed for further evaluation of the interaction between H. pylori and NSAIDs. RESULTS: Ninety-seven patients (52 gastric ulcers, 45 duodenal ulcers) and 97 non-ulcer controls were enrolled in the study. H. pylori and NSAIDs were both found to be independent risk factors for ulcer bleeding (H. pylori odds ratio, 2.22; 95% confidence interval (CI), 1.23-4.01; NSAIDs odds ratio, 4.57; 95% CI, 2.50-8.35). There was no synergistic effect. In contrast, a negative interaction was observed in the logistic regression and stratified analysis, although the difference was not significant (H. pylori adjusted odds ratio, 3.47; 95% CI, 1.73-6.95; NSAID adjusted odds ratio, 6.16; 95% CI, 3.14-12.09). CONCLUSION: H. pylori increases the risk of peptic ulcer bleeding but may play a protective role in NSAID users.

Aged↗
PubMed1999

Gastric emptying rate assessment based on the proportion of intra-abdominal radioactivity in the stomach.

UNLABELLED: Using scintigraphic techniques, the rate of gastric emptying is calculated by quantifying the absolute radioactivity within a gastric region of interest (intragastric method) with the time of meal completion considered 100% retention. However, this technique has significant limitations arising from subject movement and radionuclide gamma-ray attenuation, which may render curve fitting difficult, particularly in patients with gastroparesis. In an attempt to minimize these limitations, we have expressed the intragastric content as a percentage of the total abdominal radioactivity (abdominal method) and compared these two methods. METHODS: Forty-five subjects in a sitting position consumed a meal consisting of two fried eggs labeled with 99mTc, two slices of toast and 300 mL 5% glucose water (412 kcal). Data were acquired at a rate of one frame every 5 min from the left anterior oblique view. Using the two methods, the intragastric retention ratios at 30, 60, 90, 120 and 240 min and the 50% emptying time (T50) were obtained from both observation and calculation by power exponential fit. R2, representing goodness of fit of the nonlinear curve fitting, was calculated. RESULTS: There were no differences in the calculated values of T50 between the two methods. Quantitative estimates of T50 by extrapolation of a power exponential fit were feasible in 42 of the 45 subjects when the abdominal method was used, compared with only 29 of the 45 subjects when the intragastric method was used. In the 23 subjects with delayed emptying, quantitative estimates of T50 were feasible in 20 subjects when the abdominal method was used, compared with 7 subjects when the intragastric method was used. Using the abdominal method as opposed to the intragastric method also significantly improved R2. The difference between observed values and estimated values of T50 and intragastric retention ratios at 30, 90 and 120 min was smaller using the abdominal method. CONCLUSION: Scintigraphic measurement of gastric emptying calculated using the proportion of the abdominal radioactivity in the stomach offers substantial advantages over conventional methods, particularly in patients with gastroparesis.

Adult↗
PubMed1999

[Studies of the correlations between DNA fingerprints and meat production traits in chickens].

This study revealed correlations between DNA fingerprints (DFPs) and slaughter traits of SR92A male x Xiaoshan female hybrids with EAV (endogenous avian retroviral element) as the probe. In the DFP patterns, the band J with molecular weight of about 4 kilobasepairs correlated significantly with alive weight, dressing weight, semi-eviscerated weight, talon weight, breast muscle weight, head weight and thigh weight. The mean alive weight, dressing weight, semi-eviscerated weight and breast muscle weight are 280 g (28.57%), 225 g (28.87%), 216 g (28.76%) and 16.71 g (54.00%) higher respectively in individuals without band J than in those with band J. With the following formula: delta W = (XJ(-) - XJ+) x N x FJ+, it was estimated that an addition of 165.2 kilograms of alive weight can be achieved in a hybrid population with size of 1,000 chickens established by selecting parents without band J.

Animals↗
PubMed1998

Conformationally restricted carbamate inhibitors of horse serum butyrylcholinesterase.

Conformationally restricted carbamate inhibitors, exo-2-norbornyl-N-butylcarbamate (1), endo-2-norbornyl-N-butylcarbamate (2), l-adamantyl-N-butylcarbamate (3), and 2-adamantyl-N-butylcarbamate (4) as active site-directed irreversible inhibitors of horse serum butyrylcholinesterase are investigated for values of the dissociation constant (KI), the carbamylation constant (k2), and the bimolecular rate constant (ki). Compound 1 is the most potent inhibitor of the enzyme and the values of KI and ki are 20 nM and 1.1 x 10(5) M-1sec-1, respectively.

Animals↗
PubMed1998

A clinicopathologic study of mucinous gastric carcinoma including multivariate analysis.

BACKGROUND: Mucinous gastric carcinoma (MGC) is a rare subtype of gastric adenocarcinoma, and its clinical and pathologic features are still controversial. To clarify the significance of this subtype of carcinoma, the authors conducted a case-control study to investigate the clinicopathologic characteristics of MGC and determine whether this mucin-producing histologic type is associated with a worse prognosis than other gastric carcinomas. METHODS: Twenty-two cases of MGC and 46 patients with nonmucinous gastric carcinoma (NGC) were included. Patients were evaluated on the basis of age, gender, tumor size, location, depth of tumor invasion, histologic differentiation, lymph node involvement, organ metastasis, stage at presentation, surgical curability, adjuvant chemotherapy and radiation therapy. To determine whether the MGC itself was an independent prognostic factor, a multivariate analysis was performed with the Cox proportional hazards model. RESULTS: The MGC patients were found to have larger tumors (P < 0.001), tumors more often located in the upper stomach (P < 0.05), more serosal invasion (P < 0.05), more lymph node involvement (P < 0.05), greater frequency of advanced stage disease (P < 0.01), and lower 5-year survival rates (P < 0.05) than NGC patients. There was no significant correlation between the subtypes of differentiation of MGC and other data, including the prognosis. Multivariate analysis showed that clinically important predictive factors were serosal invasion and disease stage at diagnosis. The mucinous histologic type itself was not an independent factor for poor prognosis. CONCLUSIONS: The overall survival rate for patients with MGC was worse than that for patients with NGC. The poor prognosis was correlated with more advanced stage at diagnosis and more frequent serosal invasion, not with the mucinous histologic type.

Adenocarcinoma, Mucinous↗
PubMed1998

Small intestine dysmotility and bacterial overgrowth in cirrhotic patients with spontaneous bacterial peritonitis.

Patients with bacterial overgrowth of the small intestine developed spontaneous bacterial peritonitis (SBP) more frequently than patients without bacterial overgrowth of the small intestine. The objective of this study was to determine whether the incidences of small intestine dysmotility and bacterial overgrowth are higher in cirrhotic patients with a history of SBP than in cirrhotic patients without SBP. Forty cirrhotic patients were enrolled in this study. There were 20 patients with a history of SBP and 20 patients without a history of SBP. Small intestine bacterial overgrowth was diagnosed by breath hydrogen test. Small intestine motility was recorded, by a 3-channel solid-state manometric catheter, for 24 hours. There were no statistical differences in age or sex between the two groups. The Child-Pugh scores in the SBP group were higher than in the non-SBP group (10.5 +/- 2.1 vs. 8.1 +/- 1.9, P < .01). The incidence of bacterial overgrowth of the small intestine was higher in the SBP group than in the non-SBP group (70% vs. 20%, P < .01). The amplitude and duration of migrating motor complex (MMC) activity fronts, as well as the number of clusters per hour, were similar in both groups. However, the frequency of MMC activity fronts was higher in the non-SBP group than in the SBP group (4.8 +/- 2.3/24 hours vs. 3.5 +/- 1.2/24 hours, P < .05). In addition, the MMC velocity was significantly higher in the non-SBP group (8.3 +/- 2.6 vs. 5.3 +/- 2.1 cm/min, P < .01). The incidence of bacterial overgrowth of the small intestine was higher in cirrhotic patients with history of SBP than in those without SBP. Small intestine motility dysfunction was more severe in cirrhotic patients with history of SBP. Impaired motility of the small intestine, causing bacterial overgrowth of the small intestine, may be one of the explanations for recurrent SBP in cirrhotic patients.

Adult↗
PubMed1998

Transient impact of hemodialysis on gastric myoelectrical activity of uremic patients.

Upper gastrointestinal discomforts are common in uremic patients. Investigators have stressed the structural, histopathological, and physiological changes in the gastrointestinal tract in the past decades. Few data are available about the electrophysiological changes in the stomach of uremic patients. It is not known whether hemodialysis alters gastric myoelectrical activity. More interestingly, what is the long-term effect? To address these questions, we measured gastric myoelectrical activity before and after hemodialysis in patients with end-stage renal disease on maintenance dialysis treatment. Twenty-one uremic patients with dyspeptic complaints were enrolled in this study. Gastric myoelectrical activity was measured noninvasively using abdominal surface electrodes (electrogastrography). The paired variables obtained before and after hemodialysis were compared statistically. We also compared the difference between two subgroups defined as new hemodialysis patients and chronic hemodialysis patients. We found that there was a significantly lower percentage of normal slow-wave frequency obtained after hemodialysis in comparison with before hemodialysis (fasting state: 49.1 +/- 4.8% vs 68.1 +/- 5.4%, P < 0.01; fed state: 53.8 +/- 6.9% vs 73.4 +/- 4.1%, P < 0.01). In comparing the subgroups, there were no differences between each EGG variable. We concluded that the hemodialysis itself compromised gastric myoelectrical activity in its immediate effect. However, there were no permanent effects regarding gastric myoelectrical activity itself.

Electrocardiography↗
PubMed1998

Small-intestinal bacterial overgrowth in patients with liver cirrhosis, diagnosed with glucose H2 or CH4 breath tests.

BACKGROUND: Small-intestinal bacterial overgrowth (SIBO) has been considered a predisposing factor of spontaneous bacterial peritonitis in cirrhotic patients by bacterial translocation or hematogenous spread during spontaneous bacteremia. We investigated 45 cirrhotic patients and 28 healthy subjects to assess the prevalence of SIBO and its relationship with the severity of liver dysfunction and the presence of ascites. METHODS: Bacterial overgrowth was measured by the glucose hydrogen and methane breath test. RESULTS: SIBO was documented in 16 (35.6%) of the 45 cirrhotic patients and in 1 (3.6%) of the 28 healthy controls. The prevalence of SIBO was significantly higher in patients with Child-Pugh class B or C (50%) than in those with class A (19%) and had no relationship with the presence or absence of ascites. CONCLUSIONS: We conclude that the prevalence of SIBO in cirrhotic patients is approximately 35.6% and that it is related to the severity of liver disease. There was no difference among various causes of cirrhosis, such as viral, alcoholic, or idiopathic.

Adult↗
PubMed1998

Effect of cisapride on gastric dysrhythmia and emptying of indigestible solids in type-II diabetic patients.

BACKGROUND: Abnormal gastric slow-wave frequencies have been observed in diabetic gastroparesis. To evaluate the effect of cisapride on gastric dysrhythmia and emptying of indigestible solids, 20 type-II diabetic patients with symptoms suggestive of gastroparesis were enrolled in this study. METHODS: Cutaneous electrogastrography, gastric emptying of radiopaque markers, and evaluation of upper gastrointestinal symptoms were performed before and after administration of an 8-week course of cisapride. RESULTS: The fasting-state percentages of dominant frequency in normal and tachygastric ranges improved significantly after an 8-week course of cisapride treatment (P < 0.01 and P < 0.05, respectively). The post-meal percentages of dominant frequency in the tachygastric range also improved significantly after cisapride treatment (P < 0.05). The upper gastrointestinal symptoms score decreased significantly, and gastric emptying of radiopaque markers also increased significantly after 8 weeks of cisapride treatment (P < 0.01). CONCLUSIONS: In conclusion, this study showed that cisapride can improve gastric dysrhythmia during both fasting and post-meal phases in patients with diabetic gastroparesis. In addition, upper GI symptoms and gastric emptying of indigestible solids may also show significant improvement after 8 weeks of cisapride treatment.

Blood Glucose↗
PubMed1998

Electrogastrographic study of the effect of transcatheter arterial chemoembolization on gastric myoelectric activity.

BACKGROUND: Transcatheter arterial chemoembolization (TACE) of the hepatic artery is frequently used in the treatment of inoperable hepatocellular carcinoma (HCC). TACE causes not only effective tumor tissue necrosis in patients with hepatoma but also adverse effects on extrahepatic abdominal organs. There are no published reports on the effect of TACE on the gastric myoelectric activity. In this study, using cutaneous electrogastrography (EGG), we evaluated the effect of TACE on gastric myoelectric activity in patients with HCC. METHODS: A total of 27 patients (24 men and 3 women, aged 22 to 78 years) with hepatoma, admitted for TACE, were included in this study. Furthermore, 28 patients (24 men and 4 women, aged 26 to 75 years), admitted for diagnostic angiography of the liver, served as the control group. Cutaneous EGG was performed before and after TACE or angiography. RESULTS: In the TACE group there were significant changes in dominant frequency (DF) and percentages of DF in the defined normal range, bradygastric range, and tachygastric range on post-meal EGG. On fasting EGG, only the dominant frequency and percentages of DF in the bradygastric range changed significantly. However, there was no correlation between the occurrence of nausea/vomiting and the degree of change in the EGG variables, during both fasting and postprandial states. In the control group there were no significant differences in EGG variables before and after angiography. CONCLUSIONS: TACE can affect gastric myoelectric activity in HCC patients. Nevertheless, the relationship between changes in myoelectric activity and the occurrence of gastrointestinal symptoms needs further investigation.

Antibiotics, Antineoplastic↗