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Biomedical subjects

H C Lin

Publications and source records attributed to H C Lin.

At least 145 records · Page 8Linked to original sources
PubMed1999

Systemic administration of lipopolysaccharide induces release of nitric oxide and glutamate and c-fos expression in the nucleus tractus solitarii of rats.

There is increasing recognition that communication pathways exist between the immune system and brain, which allows bidirectional regulation of immune and brain responses to infection. The endotoxin lipopolysaccharide (LPS) has been reported to elicit release of cytokines and expression of inducible nitric oxide synthase (iNOS) in peripheral organs. Whereas LPS given systemically causes endotoxic shock, little is known about its central nervous system action, particularly the induction of iNOS. Nitric oxide (NO) and glutamate in the nucleus tractus solitarii (NTS) are important mediators of central cardiovascular regulation. We have previously demonstrated that intravenous injections of LPS increased the NO precursor L-arginine-induced depressor effect in the NTS. The present study investigated further the effects of LPS on the release of NO and glutamate in the NTS and the expression of c-fos, an immediate early response gene product, in neural substrates for central cardiovascular control. In vivo microdialysis coupled with chemiluminescence and electrochemical detection techniques were used to measure extracellular levels of NO and glutamate in the rat NTS. Immunohistochemistry was used for the examination of c-fos protein expression. We found that intravenous infusion of LPS (10 mg/kg) produced a biphasic depressor effect, with an early, sharp hypotension that partially recovered in 15 minutes and a secondary, more prolonged hypotension. In the NTS, a progressive increase of extracellular glutamate and NO levels occurred 3 and 4 hours after LPS was given, respectively. The effects of LPS on the induction of delayed hypotension and NO formation in the NTS were abolished by pretreatment with the iNOS inhibitor aminoguanidine. Finally, c-fos protein expression in the NTS and related structures for cardiovascular regulation was observed after LPS challenge. Taken together, these data suggest that an endotoxin given systemically can elicit delayed increases of glutamate release and iNOS-dependent NO production in the NTS and activate the central neural pathway for modulating cardiovascular function.

Animals↗
PubMed1999

Early dexamethasone therapy and blood cell count in preterm infants.

OBJECTIVE: To assess the effects of early postnatal dexamethasone therapy on hematologic values in preterm infants. MATERIALS AND METHODS: We reviewed the hematologic data of 179 preterm infants who participated in a double-blind clinical trial of early postnatal dexamethasone therapy (<12 hours after birth) for the prevention of chronic lung disease. One group (86 infants) received saline and the other group (93 infants) received dexamethasone. Dexamethasone was given intravenously every 12 hours in tapering doses: 0.25 mg/kg on days 1 to 7, 0.12 mg/kg on days 8 to 14, 0.05 mg/kg on days 15 to 21, and 0.02 mg/kg on days 21 to 28. Blood samples were obtained on days 0, 3, 7, 10, 14, 21, and 28. None of the infants received prenatal steroid therapy. RESULTS: Multiple regression analysis revealed significant differences in the values versus time curves of the white blood cell, neutrophil, lymphocyte, basophil, and eosinophil counts between the two groups. The white blood cell count was significantly higher in the dexamethasone group on days 7 through 14, and this was associated with significantly higher numbers of segmented neutrophils and band forms and significantly lower numbers of lymphocytes and eosinophils. The hematocrit and platelet counts were similar in the two groups throughout most of the trial. Except for platelet count, steroid therapy did not alter the hematologic values for infants with bacteremia. CONCLUSION: Dexamethasone affects white blood cell, segmented neutrophil, lymphocyte, basophil, and eosinophil counts in neonates. This should be taken into consideration when evaluating preterm infants who are receiving dexamethasone.early dexamethasone therapy; neonatal blood count; preterm infant; respiratory distress syndrome.

Bacteremia↗
PubMed1999

Muscle phosphofructokinase deficiency (Tarui's disease): report of a case.

A 14-year-old girl had an acute episode of rhabdomyolysis after vigorous exercise and seizures. Laboratory studies revealed elevated creatine phosphokinase (CPK) activity and myoglobinuria without acute renal failure, as well as mild indirect hyperbilirubinemia, and hyperuricemia. The elevated CPK activity, mild indirect hyperbilirubinemia, and hyperuricemia persisted during a 10-month follow-up period, during which chronic hemolysis without overt anemia was also noted. A muscle biopsy specimen from the left biceps muscle revealed occasional muscle fiber necrosis and mild excess of glycogen accumulation on periodic acid-Schiff staining. Histochemical reactions were negative with phosphofructokinase (PFK) stain when fructose-6-phosphate was used as the substrate, but positive when fructose 1,6-bisphosphate was used as the substrate. These findings confirmed the diagnosis of muscle PFK deficiency (Tarui's disease), which is a defect of glycolysis in muscles and erythrocytes. Less than 40 such patients have been reported to date. When a specific metabolic myopathy is suspected in children with rhabdomyolysis, symptoms of hemolysis should also be sought to identify Tarui's disease. To the best of our knowledge, this is the first case of Tarui's disease identified in Taiwan.

Adolescent↗
PubMed1999

Plasma concentrations of interferon-alpha in patients with liver cirrhosis: relationship to systemic and portal hemodynamics.

BACKGROUND: Nitric oxide (NO) plays an important role in the pathogenesis of the hyperdynamic circulation observed in portal hypertensive states. Interferon (IFN)-alpha can stimulate NO formation directly or indirectly via cytokines. However, IFN-alpha concentrations seem to increase or decrease in cirrhotic patients. This study investigated the plasma concentration of IFN-alpha in patients with cirrhosis and its relationship to systemic and portal hemodynamics. METHODS: Thirty-six patients with cirrhosis and 47 healthy controls had blood samples taken for the determination of plasma concentrations of IFN-alpha by enzyme-linked immunosorbent assay. Systemic and portal hemodynamics were measured in patients with cirrhosis on the same day of blood sampling using Swan-Ganz catheterization and the thermodilution technique. RESULTS: As compared with healthy subjects, patients with cirrhosis demonstrated a significantly higher IFN-alpha detectable rate (> 3 pg/ml, 14.9% vs 36.1%, p < 0.05). In cirrhotic patients, the IFN-alpha detectable rates were similar between those with and without decompensation, a hepatic venous pressure gradient greater than 12 mmHg, or the presence of large esophageal varices (p > 0.05). There was no significant difference in the systemic vascular resistance or hepatic venous pressure gradient between cirrhotic patients with and without a detectable plasma IFN-alpha concentration. CONCLUSIONS: Plasma IFN-alpha concentrations tended to increase in patients with cirrhosis. However, IFN-alpha concentrations do not play a role in the hyperdynamic circulation observed in patients with cirrhosis.

Adult↗
PubMed1999

Hemostatic changes in patients with liver cirrhosis.

BACKGROUND: Hemostatic changes in liver disease are complicated. An overall evaluation of the main hemostatic parameters in patients with different degrees of cirrhosis of the liver has not been reported in Taiwan. METHODS: A series of hemostatic tests and parameters including activated partial thromboplastin time, prothrombin time, thrombin time, bleeding time, factor VIII assay, antithrombin activity, fibrinogen, plasminogen, protamine sulfate test, fibrin(ogen) degradation products, D-dimer, thrombin-antithrombin complex (measured by modified antithrombin), tissue plasminogen activator (tPA), plasminogen activator inhibitor-1, euglobulin lysis test and venous occlusion test were performed in 51 patients with cirrhosis of the liver and 33 healthy controls. Among the cirrhotics, 18 were classified as Child-Pugh group A, 16 were B and 17 were C. RESULTS: Plasminogen, antithrombin and platelet count decreased progressively, starting with group A, then B and then C, relative to the controls. Factor VIII, activated partial thromboplastin time, prothrombin time, bleeding time, D-dimer and fibrin(ogen) degradation products increased progressively starting with group A, to B and then C, relative to controls. Severity of cirrhosis correlated with hemostatic changes. No significant change in the fibrinolytic response after challenge with the venous occlusion test was found in either Child-Pugh groups A, B, C or the controls, though progressive increases in tPA were found starting with group A, to B and then C, relative to controls. CONCLUSIONS: Our study proved a close relationship between the severity of cirrhosis and hemostatic changes. Activated partial thromboplastin time was better than bleeding time or thrombin time to demonstrate the severity of liver damage and hemostatic change in cirrhosis. Because the deterioration of coagulation function and increased fibrinolytic activity paralleled the severity of liver cirrhosis, adequate treatment for cirrhotic bleeding should not only correct the coagulation defects, but should also lower the increasing fibrinolytic activity.

Adult↗
PubMed1999

Prevalence of antimicrobial resistance among clinical isolates of Haemophilus influenzae in Taiwan.

The purpose of this study was to determine the prevalence of resistance to various antimicrobial drugs among Haemophilus influenzae isolates in Taiwan. Two hundred and ninety-six clinical isolates of H. influenzae were prospectively obtained from nine teaching hospitals throughout Taiwan, from June 1994 to April 1995. All isolates were examined for the presence of type b encapsulation and beta-lactamase production. Antibiotic susceptibility was determined by means of standard broth microdilution procedures. Twenty-three isolates (7.8%) were type b, and the overall rate of beta-lactamase production was 58.1% (172/296). The rates of resistance to antibiotics were 58.1% for ampicillin, 33.8% for trimethoprim-sulfamethoxazole, 20.6% for chloramphenicol, 27% for tetracycline, 6.7% for azithromycin, 3.4% for cefaclor, and 0.3% for cefuroxime. Cefixime, ceftriaxone, and ciprofloxacin were active against all H. influenzae isolates. Thirty (10.1%) of the 296 isolates were resistant to three drugs (ampicillin, chloramphenicol, and tetracycline), 16 of which (5.4%) were resistant to four drugs (ampicillin, chloramphenicol, tetracycline, and trimethoprim-sulfamethoxazole). There was a marked increase in the rates of ampicillin resistance and beta-lactamase production among H. influenzae isolates compared with a previous survey in Taiwan conducted 9 years ago. In addition, isolates with multiple drug resistance were also identified. Continued efforts are needed to monitor antibiotic resistance patterns of H. influenzae in the region.

Drug Resistance, Microbial↗
PubMed1999

Beneficial effects of combined terlipressin and tetramethylpyrazine administration on portal hypertensive rats.

The purpose of this study was to investigate the therapeutic effects of terlipressin (TP) alone or in combination with tetramethylpyrazine (TMP) on anesthetized portal hypertensive rats. Portal hypertension was induced by either partial portal vein ligation (PVL, without cirrhosis) or bile duct ligation (BDL, with cirrhosis) in Sprague-Dawley rats. Each PVL or BDL rat received only one of the two regimens: vehicle for 3 min followed by TP (0.017 mg x kg(-1) x min(-1) for 3 min) or TMP (10 mg x kg(-1) x min(-1) for 3 min) followed by TP. In PVL rats, infusion of vehicle followed by TP induced significant reduction of portal venous pressure (PVP, -15.0+/-1.0%) and prominent elevation of mean arterial pressure (MAP, 57.3+/-8.1%) as well as total peripheral resistance (TPR, 113+/-11%) from baseline, and there was a cardiodepressant response (cardiac index, CI, -26.3+/-1.1%). Infusion of TMP followed by TP induced significant reduction of PVP (-20.3+/-0.4%) and CI (-9.9+/-1.2%) and significant elevation of MAP (31.3+/-2.5%) and TPR (46.0+/-4.1%) from baseline. In BDL rats, infusion of vehicle followed by TP also induced significant reduction of PVP (-13.8+/-1.7%) but an increase in MAP (57.1+/-2.2%) and TPR (101+/-6%) from baseline, and there also was a cardiodepressant response (CI, -21.4+/-2.3%). Infusion of TMP followed by TP induced significant reduction of PVP (-18.9+/-1.4%) and CI (-11.9+/-2.1%), but an increase in MAP (36.2+/-2.5%) and TPR (55.0+/-5.2%). Compared with vehicle followed by TP, TMP not only significantly enhanced portal hypotensive (PVP reduction) effects of TP but also attenuated the systemic pressor (MAP and TPR elevation) and cardiodepressant (CI reduction) effects of TP in both PVL and BDL rats. Our results suggest that TP, alone or in combination with TMP, induced portal hypotensive effects in two models of portal hypertensive rats. Combination of TP and TMP was beneficial in enhancing portal hypotensive effects of TP and ameliorating the systemic pressor and cardiodepressant effects of TP.

Animals↗
PubMed1999

Neutrophil adherence to lung epithelial cells induce interleukin-8 release.

BACKGROUND: Neutrophil recruitment to the lungs and transmigration through the pulmonary epithelium to reach the respiratory tract are characteristics of airway inflammation. Interleukin-8 (IL-8) plays a critical role in the recruitment of neutrophils to epithelial cells. We investigated the effect of neutrophil adherence to epithelial cells on cytokine secretion. METHODS: The production of IL-8 from cultured A549 epithelial cells was assayed and neutrophil adherence assay in the presence or absence of interferon-gamma (IFN-gamma) plus tumor necrosis factor-alpha (TNF-alpha) plus interleukin-1 beta (IL-1 beta) stimulation was studied on cultured A549 epithelial cells. The role of an adhesion molecule in the modulation of neutrophil adherence was examined by pretreatment with intercellular adhesion molecule-1 (ICAM-1) blocking antibody. RESULTS: There was an increase in IL-8 release from epithelial cells that was time-dependent and in the magnitude of neutrophil adherence to the epithelial cells. Stimulation of epithelial cells with IFN-gamma +TNF-alpha +IL-1 beta significantly increased IL-8 release and neutrophil adherence. The spontaneous or IFN-gamma +TNF-alpha +IL-1 beta-induced IL-8 release was significantly augmented after the addition of neutrophils. The inhibition of neutrophil adherence to epithelial cells by ICAM-1 blocking antibody downregulated the augmented release of IL-8 with or without IFN-gamma +TNF-alpha +IL-1 beta stimulation. Placing a membrane filter on cultured epithelial cells to prevent neutrophil adherence significantly decreased IL-8 release from epithelial cells with IFN-gamma +TNF-alpha +IL-1 beta stimulation. CONCLUSION: Our results indicate that lung epithelial cells not only provide a harboring site for neutrophils to be activated, but also amplify the neutrophil sequestration in the lung by releasing IL-8. Moreover, the release of IL-8 is dependent on the adherence between neutrophils and lung epithelial cells.

Cell Adhesion↗
PubMed1999

Immunogenicity of oral poliovirus vaccine in Taiwan.

Previous studies have shown that the immune response to trivalent oral poliovirus vaccine (OPV) varies widely from country to country. However, there has been no report on the immunogenicity of this vaccine in Taiwanese children. In this study, 98 children were followed up for 17 months to study the antibody responses following four doses of trivalent OPV. The results showed that, after two doses of vaccine, all children were protected against poliovirus type 1 and 2. All except two children also developed protective antibodies against poliovirus type 3. After three doses, the antibody levels in all subjects were above protective concentrations. The fourth dose, given at 18 months of age, further boosted the antibody titers. These findings show that the OPV currently used in Taiwan is highly immunogenic in Taiwanese children.

Antibodies, Viral↗
PubMed1999

Penicillin-nonsusceptible Streptococcus pneumoniae infections in children.

The emergence of penicillin-nonsusceptible Streptococcus pneumoniae (PNSSP) has brought a new clinical challenge. In Taiwan, reports of the prevalence and clinical features of PNSSP infections in children are limited. This study reviewed the resistance patterns of all clinical isolates of S. pneumoniae obtained from patients under 17 years of age from January 1993 through July 1998 in a medical center. Their clinical features and treatment responses were analyzed, with special attention paid to those patients with invasive PNSSP infections. Totally, 170 clinical isolates of S. pneumoniae were obtained from 168 patients aged under 17 years. Among those infections, there were 56 sinusitis (including 4 sinusitis with bacteremia), 44 pneumonia (including 23 pneumonia with bacteremia or empyema), 23 otitis media (including 5 otitis media with bacteremia), 9 simple bacteremia, 9 conjunctivitis, 8 meningitis, 4 peritonitis, 3 skin infections and the other 14 isolates were colonization. One hundred eleven isolates (65.3%) showed reduced penicillin susceptibility by the disk diffusion method. A trend of increasing percentiles of PRSP was noted: 27.3% (3/11) in 1993, 37.5% (9/24) in 1994, 55.5% (10/18) in 1995, 77.5% (31/40) in 1996, 66.0% (31/47) in 1997, and 87.1% (27/31) in 1998. Minimum inhibitory concentration (MIC) determinations by the E-test showed some of the isolates were intermediately resistant. Prior antibiotic usage was associated with a higher incidence of PNSSP infections. However, most children responded well to antimicrobial treatment.

Adolescent↗
PubMed1999

Isolation of Japanese encephalitis virus from mosquitoes collected in Northern Taiwan between 1995 and 1996.

Mosquito collections were carried out from May to October in 1995 and 1996 at Yingko and Sanhsia of Taipei County and Chunan of Miaoli County. A grand total of 13,576 mosquitoes consisting of 13 species in 407 pools were processed and inoculated into Aedes albopictus clone C6/36 cell cultures. One hundred thirty seven pools of these showed the presence of viral antigens in the infected C6/36 cell lysates which were identified by the indirect fluorescent antibody test using a monoclonal antibody against Japanese encephalitis (JE) virus. The postive pools, were divided into 97, 20, 1, 8, 1, 1, 7, and 2 pools from Culex tritaeniorhynchus Giles, Aedes albopictus Skuse, Aedes vexans nocturnus (Theobald), Armigeres subalbatus (Coquillett), Culex annulus Theobald, Culex fuscanus Wiedemann, Culex quinquefasciatus Say, and Culex sitiens Wiedemann respectively. The dominant species collected at night was Culex tritaeniorhynchus, while Aedes albopictus was the dominant species collected in daytime. Besides the pigpens, avian habitats are also a dominate source of JE virus in this study.

Animals↗
PubMed1998

Modulatory impact of cardiac rehabilitation on hyperhomocysteinemia in patients with coronary artery disease and "normal" lipid levels.

In coronary patients with "relatively normal" lipid values and hyperhomocystinemia (levels > or =15 micromol/L), significant 12% reductions in homocysteine levels occurred after cardiac rehabilitation and exercise training. This benefit from cardiac rehabilitation and exercise training may lead to 20% to 30% reductions in overall coronary artery disease risk.

Aged↗
PubMed1998

Involvement of PKC-alpha in regulatory volume decrease responses and activation of volume-sensitive chloride channels in human cervical cancer HT-3 cells.

1. The present study was carried out to identify the specific protein kinase C (PKC) isoform involved in regulatory volume decrease (RVD) responses, and to investigate the signal transduction pathways underlying the activation of volume-sensitive chloride channels in human cervical cancer HT-3 cells. The role of Ca2+ in RVD and in the activation of chloride currents was also studied. 2. The time course of RVDs was prolonged by microinjection of PKC-alpha antibody but not by PKC-beta or PKC-gamma antibody, and also by exposure to Ca2+-free medium, in particular when combined with microinjection of EDTA. Immunofluorescence staining showed that hypotonic superfusion evoked the translocation of PKC-alpha to the cell membrane, whereas PKC-beta or PKC-gamma remained unaffected. The translocation of PKC-alpha was observed a few minutes after hypotonic stress, reaching peak intensity at 30 min, and returned to the cytoplasm 60 min after hypotonic exposure. Western blot analyses showed an increased PKC-alpha level in terms of intensity and phosphorylation in the cell membrane, while neither PKC-beta nor PKC-gamma was activated upon hyposmotic challenge. 3. Whole-cell patch-clamp studies demonstrated that neomycin and PKC blockers such as staurosporine and H7 inhibited volume-sensitive chloride currents. The inhibitory effect of neomycin on chloride currents can be reversed by the PKC activator phorbol 12-myristate, 13-acetate (PMA). Moreover, the PKC inhibitor and PKC-alpha antibody, but not PKC-beta or PKC-gamma antibody, significantly attenuated the chloride currents. The activation of volume-sensitive chloride currents were insensitive to the changes of intracellular Ca2+ but required the presence of extracellular Ca2+. 4. Our results suggest the involvement of PKC-alpha and extracellular Ca2+ in RVD responses and the activation of volume-sensitive chloride channels in HT-3 cells.

Blotting, Western↗
PubMed1998

Sequestration of the G protein beta gamma subunit complex inhibits receptor-mediated endocytosis.

Cell surface receptors that mediate endocytosis cluster into clathrin-coated pits, which pinch off to form vesicles that transport the receptors and their ligands. This multi-step process requires the coordinated action of many factors, including GTP-hydrolyzing proteins such as dynamin and regulators of actin cytoskeleton assembly. We note herein that sequestration of heterotrimeric G protein beta gamma subunits in intact cells strongly inhibits clathrin-coated pit-mediated endocytosis and causes rearrangement of the actin cytoskeleton. Our results suggest that cells contain a pool of free beta gamma and that it functions constitutively to permit endocytosis.

Actin Cytoskeleton↗
PubMed1998

Stereochemistry and biological activities of constituents from Cynanchum taiwanianum.

The stereochemistry of new acetophenones, cynandione B-D (2-4), isolated from Cynanchum taiwanianum, elucidated by computer modelling calculation and NOESY spectrum. It establishes the absolute configurations of cynandiones B-D (2-4) as 7R; 7"S, 7S; 7"S and 7R; 7"R, respectively. Cynandione B (2) strongly inhibited the release of beta-glucuronidase and lysozyme in formyl-methionyl-leucyl-phenylalanine (fMLP)-stimulated rat neutrophils in a concentration-dependent manner with IC50 values of 1.5 +/- 0.2 and 1.6 +/- 0.2 microM, respectively. 2,5-Dihydroxyacetophenone (6) strongly inhibited the aggregation of washed rabbit platelets induced by arachidonic acid in a concentration-dependent manner with an IC50 value of about 4.8 microM. In human citrated platelet-rich plasma, 2,5-dihydroxyacetophenone (6) inhibited the secondary phase, but not the primary phase, of aggregation induced by adrenaline and ADP. These results suggest that the antiplatelet effect of 2,5-dihydroxyacetophenone (6) is due to inhibition of the formation of thromboxane A2.

Acetophenones↗