Biomedical subjects

S J Chang

Publications and source records attributed to S J Chang.

At least 37 records · Page 2Linked to original sources

PubMed2000

Effect of Korea red ginseng on the blood pressure in conscious hypertensive rats.

The change of blood pressure and heart rate after intravenous injection of Korea red ginseng (KRG) were studied in the conscious normotensive and one-kidney, one-clip Goldblatt hypertensive (1K, 1C-GBH) rats. Crude saponin (CS) of KRG (50, 100 mg/kg i.v.) induced a hypotensive effect and bradycardia in a dose-dependent manner in the anesthetized rats. On the other hand, CS of KRG (100 mg/kg) induced a hypotensive effect and reflex tachycardia in the conscious rats. Saponin-free fraction (SFF) of KRG did not affect them in the anesthetized normotensive rats (P>.05). The maximal hypotensive effect by CS of KRG in the conscious 1K, 1C-GBH hypertensive rats and L-nitroarginine methyl ester (L-NAME, 40 mg/kg)-treated conscious hypertensive rats was not different from that of conscious normotensive rats (Delta 31.6+/-6.3, Delta 27.5+/-5.8 vs. Delta 26.7+/-4.3 mmHg, P>.05). However, pretreatment of L-NAME significantly inhibited the reflex tachycardia by CS of KRG (70.8+/-7.0 vs. 30.6+/-15.0 bpm, P<.05). Hemolysate-sensitive nitric oxide (NO) current by the CS of KRG was greater than that of the SFF of KRG (651.9+/-128.2 pA for CS and 164.9+/-92.5 pA for SFF, P<.001). These findings suggest that KRG has a hypotensive effect and its effect may be due to saponin fraction of KRG in the conscious rats. The releasing effect of NO of KRG, like NO donor, may be partly contributed to the hypotensive effect of KRG.

Animals↗

PubMed2000

The conditional survival statistics for survivors with primary supratentorial astrocytic tumors.

BACKGROUND: Relative survival rates can offer a general description of tumor outcome and, traditionally, are used for surveillance and comparison purposes. However, they are not informative for individual tumor survivors. Conditional survival estimates can calculate the probability of surviving next some years given survival to a specific period of time after craniotomy for individual tumor survivors. However, clinically, they have not been used for predicting the tumor outcome. METHODS: We calculated conditional probabilities of survival within 6 years after craniotomy in 112 patients with primary supratentorial astrocytic tumors and evaluated factors affecting the survival time more than 2 years after craniotomy. RESULTS: Our data showed that the conditional probability of survival can predict yearly survival rate when patients survive for a specific period of time. The conditional survival rates within 6 years after craniotomy were always higher than those evaluated by relative survival rates. Overall, the longer the patients survived, the higher the conditional probabilities of surviving sixth year postoperatively were. CONCLUSION: Our study demonstrates the conditional probabilities of survival have good availability and are important estimates for individual tumor survivors.

Adolescent↗

PubMed2000

Pneumococcal and influenza immunization and human immunodeficiency virus load in children.

OBJECTIVE: HIV-infected children receiving influenza vaccine, pneumococcal vaccine and both vaccines concurrently were studied to examine the effect of immunization on plasma HIV viral load. METHODS: Thirteen children received immunizations: pneumococcal vaccine, 5; pneumococcal and influenza vaccines, 7; and influenza vaccine, 1. Most patients (12 of 13) were receiving combination reverse transcriptase inhibitor antiretroviral therapy without protease inhibitors at the time of immunization. Baseline plasma HIV RNA was determined 1 month prior (11 of 13), 2 weeks prior (12 of 13) and on the day of immunization (12 of 13). Plasma HIV RNA was assayed at 2 weeks (11 of 13), 4 weeks (12 of 13) and 3 months (5 of 13) after immunization. T cell activation markers (HLA-DR+, CD38+ and CD45RO+, CD28+) were examined for both CD4+ and CD8+ lymphocytes on the day of immunization and 2 weeks after immunization for 11 children. RESULTS: Only one child developed a >0.5-log increase in viral load at any time after immunization. There was no correlation between an increase in viral load and antibody response to pneumococcal vaccine. At least one activation marker increased (> 10%) for two children receiving pneumococcal vaccine and two children receiving pneumococcal and influenza vaccines. One of these children experienced an increase in viral load. CONCLUSION: Immunization with pneumococcal and influenza vaccines, alone or in combination, is rarely associated with a significant increase in HIV plasma RNA in children receiving combination antiretroviral therapy.

Anti-HIV Agents↗

PubMed2000

Immunogenicity of a Haemophilus influenzae type b-tetanus toxoid conjugate vaccine when mixed with a diphtheria-tetanus-acellular pertussis-hepatitis B combination vaccine.

BACKGROUND: Combination vaccines are urgently needed to reduce the number of injections given to young children. The aim of the study was to evaluate the safety and immunogenicity of a combination vaccine that contains diphtheria and tetanus toxoids and acellular pertussis antigens (DTaP), recombinant hepatitis B surface antigen (HepB) and Haemophilus influenzae type b (Hib) polysaccharide conjugated to tetanus toxoid (PRP-T). METHODS: Four hundred five infants were randomized equally to three groups and immunized at 2, 4 and 6 months of age with: (1) DTaP/HepB vaccine used to reconstitute lyophilized PRP-T vaccine and administered as a single injection; (2) DTaP/HepB vaccine and PRP-T vaccine administered as two separate injections; or (3) DTaP, HepB and PRP-T vaccines administered as three separate injections. Safety was closely monitored, and blood specimens were obtained to assess antibody responses to each vaccine antigen. RESULTS: All study vaccines were well-tolerated, and the rates of systemic and injection site reactions were similar between groups. After the third dose the geometric mean antibody concentrations to Hib were significantly lower in subjects in Group 1 (1.63 microg/ml) compared with subjects in Groups 2 and 3 (6.26 and 6.15 microg/ml, respectively; P < 0.0001). Subjects with antibody concentrations <1.0 microg/ml after the third dose responded well to a booster dose of Hib conjugate vaccine given at 11 to 15 months of age (41 of 44 with anti-PRP > or = 1.0 microg/ml). Differences between groups for antibody responses to the other vaccine components were not clinically significant. CONCLUSIONS: Infants given a combined DTaP/ HepB/PRP-T vaccine experienced a significantly lower antibody response to the PRP-T component than infants given PRP-T vaccine as a separate injection. However, the immune response to a booster dose of Hib conjugate vaccine indicated the presence of immunologic memory.

Antibodies, Bacterial↗

PubMed2000

A protein kinase activity associated with Epstein-Barr virus BGLF4 phosphorylates the viral early antigen EA-D in vitro.

The Epstein-Barr virus (EBV) open reading frame BGLF4 was identified as a potential Ser/Thr protein kinase gene through the recognition of amino acid sequence motifs characteristic of conserved regions within the catalytic domains of protein kinases. In order to investigate this potential kinase activity, BGLF4 was expressed in Escherichia coli and the purified protein was used to generate a specific antiserum. Recombinant vaccinia virus vTF7-3, which expresses the T7 RNA polymerase, was used to infect 293 and 293T cells after transient transfection with a plasmid containing BGLF4 under the control of the T7 promoter. Autophosphorylation of the BGLF4 protein was demonstrated using the specific antiserum in an immune complex kinase assay. In addition, EBNA-1-tagged BGLF4 and EBNA-1 monoclonal antibody 5C11 were used to demonstrate the specificity of the kinase activity and to locate BGLF4 in the cytoplasm of transfected cells. Manganese ions were found to be essential for autophosphorylation of BGLF4, and magnesium can stimulate the activity. BGLF4 can utilize GTP, in addition to ATP, as a phosphate donor in this assay. BGLF4 can phosphorylate histone and casein in vitro. Among the potential viral protein substrates we examined, the EBV early antigen (EA-D, BMRF1), a DNA polymerase accessory factor and an important transactivator during lytic infection, was found to be phosphorylated by BGLF4 in vitro. Amino acids 1 to 26 of BGLF4, but not the predicted conserved catalytic domain, were found to be essential for autophosphorylation of BGLF4.

Amino Acid Sequence↗

PubMed2000

A local training and pruning approach for neural networks.

The training of neural networks using the extended Kalman filter (EKF) algorithm is plagued by the drawback of high computational complexity and storage requirement that may become prohibitive even for networks of moderate size. In this paper, we present a local EKF training and pruning approach that can solve this problem. In particular, the by-products obtained along with the local EKF training can be utilized to measure the importance of the network weights. Comparing with the original global approach, the proposed local EKF training and pruning approach results in a much lower computational complexity and storage requirement. Hence, it is more practical in solving real world problems. The performance of the proposed algorithm is demonstrated on one medium- and one large-scale problems, namely, sunspot data prediction and handwritten digit recognition.

Algorithms↗

PubMed2000

Effect of high blood flow on the expression of endothelial constitutive nitric oxide synthase in rats with femoral arteriovenous shunts.

The effect of high blood flow on the expression of endothelial nitric oxide synthase has been investigated in the femoral arteriovenous shunt (AVS) rats created by inserting U-shaped polyurethane tubes in the left femoral arteries and veins. Three days after inserting the femoral AVS, the mean aortic blood flow rate in the abdominal aorta of the AVS rats was about 2.0 times higher than that in the control rats (110.0 +/- 8.4 ml/min vs 52.7 +/- 2.7 ml/min, p < 0.001). The competitive reverse transcriptase-polymerase chain reaction (RT-PCR) data revealed that the mRNA expression level of the endothelial constitutive nitric oxide synthase (ecNOS) was increased in the aortas of the femoral AVS rats compared to that in the control rats. Western blot analysis using a monoclonal antibody against ecNOS revealed that the ecNOS protein levels were markedly increased in the aortas of femoral AVS rats, but ecNOS protein levels in aortas without endothelium were not significantly increased. Inducible nitric oxide synthase (iNOS) protein was not expressed in the aortic tissues with and without endothelium in the control rats. This iNOS expression was not increased by the high blood flow in the femoral AVS rats. These findings suggest that high blood flow could up-regulate the expression levels of ecNOS mRNA and proteins in femoral arteriovenous shunt rats.

Animals↗

PubMed2000

Vitamin B6 antagonists alter the function and ultrastructure of mice endothelial cells.

Vitamin B6, is necessary for normal membrane function and stability. Here we studied both the function and ultrastructure of aortic and arterial endothelial cells (ECs) in vitamin B6 deficient mice induced by vitamin B6 antagonists, 4-deoxypyridoxine x HCl (dPN x HCl), and isonicotinylhydrazide (INH). Mice were fed with normal laboratory chow and divided into three groups according to their drinking water. Mice in group I had distilled water and served as a control; group II had 0.1 mg dPN x HCl/mL H2O; and group III had 0.4 mg INH/mL H2O. After 5 mo, plasma concentrations of B6 vitamers pyridoxal-5'-phosphate (PLP) and pyridoxal (PL) were analyzed by HPLC. With the arachidonic acid (AA) as a precursor, prostacyclin (PGI2) production from ECs assayed by thin-layer chromatography (TLC) was used as an indicator of endothelial function. Aorta and arteriole from foot pad were removed, stained with osmium tetraoxide, and examined under transmission electron microscopy (TEM) to study the ultrastructure of ECs. The results showed that plasma concentrations of PLP, PL, and total B6 were the lowest for mice fed with INH. followed by that with dPN x HCl, compared with that of control. PGI2 production was paralleled with the plasma vitamin B6 status, with the lowest level for INH, followed by the dPN-treated group. Abnormalities in the ultrastructure of ECs were found in both dPN x HCl and INH groups, including cells detached from underlying elastic tissue, with prominent pinocytotic vesicles and swelling and/or indistinct cristae of mitochondria. These results suggest that vitamin B6 antagonists induce a deficient status that alters the function and the ultrastructure of ECs detrimental to vascular disease.

Animals↗

PubMed2000

[High-level expression of BYDV GAV coat protein gene in Escherichia coli].

The IPTG-inducible expression vector containing the BYDV GAV coat protein gene was constructed and transferred into E. coli BL21(DE3). High-level expression of the specific protein was achieved by IPTG induction. The results of SDS-PAGE and Western blotting show that the expression product which accumulates 19.5% of the total cellular proteins estimated by scanning is 24 kD BYDV GAV coat protein plus eleven amino acids of pET-5a.

Capsid↗

PubMed2000

Effect of Korean red ginseng on blood pressure and nitric oxide production.

AIM: To investigate the effect of crude saponin and nonsaponin fraction of Korean red ginseng (KRG) on the blood pressure and nitric oxide (NO) production in the conscious rats and cultured endothelial cell line, ECV 304 cells. METHODS: Systolic blood pressure and heart rate were monitored in the conscious rats. Nitric oxide levels and the expression of nitric oxide synthase were measured by a spectrophotometric assay using Griess reagents and Western blotting, respectively. Nitric-oxide synthase activity was measured based on the conversion rate of [3H]arginine to [3H]citrulline. RESULTS: Systolic blood pressure was decreased by crude saponin (100 mg/kg, i.v.) of KRG in the conscious control and one-kidney, one-clip Goldblatt hypertensive (1K, 1C-GBH) rats. The hypotensive effect induced by crude saponin of KRG reached maximum at 2-4 min and slowly recovered after 20 min to the initial level in both groups. Crude saponin of KRG induced tachycardia in the conscious rats but induced bradycardia in the anesthetized rats. In contrast to crude saponin of KRG, hypotensive effect induced by saponin-free fraction was minimal. Nitric oxide concentrations were increased by the treatment of crude saponin in conscious rats as well as in the cultured ECV 304 cells. The protein expression level of endothelial constitutive nitric-oxide synthase (eNOS) in the aorta of rats was not increased by crude saponin (100 mg/kg, i.p. for 3 d). However, nitric-oxide synthase activity was increased by crude saponin of KRG in the aortic homogenate of rats. CONCLUSION: The hypotensive effect of red ginseng is mainly due to saponin fraction of KRG in the conscious rats, and this effect may be due to an increase in the nitric-oxide production by KRG.

Animals↗

PubMed1999

Hierarchical order of critical residues on the immunity-determining region of the Im7 protein which confer specific immunity to its cognate colicin.

The directed mutagenesis study of the Im7 protein of colicin E7 revealed that three residues, D31, D35, and E39, located in the loop 1 and helix 2 regions of the protein were critical for initiating the complex formation with its cognate colicin E7. Interestingly, the importance of these three critical residues in conferring specific immunity to its own colicin was exhibited in a hierarchical order, respectively. Moreover, we found that existence of the three critical residues was common among the DNase-type Im proteins. Most likely the three residues of the DNase-type immunity proteins are critical for initiating the unique protein-protein interactions with their cognate colicin. In addition, replacement of the helix 2 of Im7 by the corresponding region of Im8 produced a phenotype of the mutant protein very similar to that of Im8. This result suggests that the DNase-type Im proteins indeed share a "homologous-structural framework" and evolution of the Im proteins may be engendered by minor amino acid changes in this specific immunity-determining region without causing structural alteration of the proteins.

Amino Acid Sequence↗

PubMed1999

Effect of heavy metal stressors and salinity shock on the susceptibility of grouper (Epinephelus sp.) to infectious pancreatic necrosis virus.

In the present study, attempts were made to clarify the effect of heavy metal stressors and salinity shock on the disease susceptibility of grouper fry (Epinephelus sp.) to infectious pancreatic necrosis virus (IPNV) infection. Zinc, cadmium and copper (5 ppm ZnCl2, 3 ppm CdCl2 and 1 ppm CuCl2) were used to treat groupers before and after virus infection. Cumulative mortalities in the experimental groups were 96-100% within 42 days. Only 5-15% mortalities were observed in most of the groups that were exposed to either heavy metals or virus infection alone. Subsequently, virus was re-isolated from the experimentally infected groupers, and copper concentration was measured in fish that had been exposed to CuCl2. We also investigated the effect of salinity shock (i.e. an abrupt change of salinity level from 33 ppt to either 40 ppt or 20 ppt) on susceptibility of grouper to IPNV. Similar results were obtained, mortalities of groupers in the experimental groups reached 80-100%. The results of the present study suggest that an IPN virus with only low pathogenicity could cause high mortality in groupers when combined with environmental stress.

Animals↗

PubMed1999

Hepatitis C virus infection among short-term intravenous drug users in southern Taiwan.

The purpose of this study was to determine the correlation between the prevalence of hepatitis C virus (HCV) infection with duration of drug use and other risk factors among drug users. This survey covered 899 male drug users from Kaohsiung Narcotic Abstention Institute and Kaohsiung prison. The prevalence of positive anti-HCV was 67.2% among intravenous drug users (IVDU) and 14.7% among non-intravenous drug users (non-IVDU). Among intravenous (IV) drug users, age and duration of drug use were independently related to HCV seropositivity. Seroprevalence rate for HCV in the IVDU group increased with increasing duration of injection use within the first seven years of drug use. However, the steepest trajectory in seroprevalence of HCV infection occurred within the first four months. Due to the high rate of HCV infection among drug users, investigation of risk behaviors should be routine in such a group. A high frequency of HCV infection was also found among short-term injectors, which indicated that early risk reduction intervention was an important measure in moderating HCV infection.

Adolescent↗

PubMed1999

Microcapsules prepared from alginate and a photosensitive poly(L-lysine).

A photosensitive polymer, alpha-phenylcinnamylideneacetylated poly(L-lysine), was synthesized and characterized. This photosensitive poly(L-lysine) had 10% of its lysine residues reacted with alpha-phenylcinnamylidene acetyl group and displayed an absorption maximum at 329 nm. The photosensitive poly(L-lysine) was used for the preparation of microcapsules. The capsules formed from this photosensitive poly(L-lysine) and alginate were strengthened significantly by light irradiation. The photo cross-linked capsular membrane was permeable to proteins with mass transfer rate in the descending order: cytochrome C, myoglobin. and serum albumin. GH3 (a rat pituitary tumor cell line) cells were encapsulated and cultured with this microencapsulation system. The cells proliferated to a density of about 4 x 10(5) cells ml(-1) in the capsules after 6 days cultivation.

Alginates↗

PubMed1999

Amination of polycarbonate surface and its application for cell attachment.

The polycarbonate sheet was modified with ammonia gaseous plasma and characterized by the contact angle measurement and ESCA analysis. The contact angles decreased significantly from 77 degrees to about 20 degrees-40 degrees, indicate that the polycarbonate sheet become more hydrophilic after plasma treatment. The ESCA analysis results showed that the hydrophilicity was mainly derived from the amino groups on the modified surface. In this study, a flow-chamber system was also constructed to evaluate the 3T3 fibroblast cells attachment phenomena on these modified sheets. Before the experimental run, the parameters of inoculated cell number and cell passage were examined previously. The results revealed that these two parameters are independent in shear experiment. And besides, 3-hours plating time has the better adhering fraction. The experimental results showed that the 3T3 fibroblast cells adhesion strength increased significantly on the plasma modified sheet.

3T3 Cells↗

PubMed1999

Adequacy of maternal pyridoxine supplementation during pregnancy in relation to the vitamin B6 status and growth of neonates at birth.

To evaluate the adequacy of maternal pyridoxine supplementation during pregnancy for both maternal and neonatal status at birth, vitamin B6 status, assessed by plasma pyridoxal phosphate (PLP), pyridoxal (PL) and total aldehyde vitamer (PLP + PL) concentrations, and the growth of neonates, including weight, length, head and chest circumferences, were examined for 209 neonates whose mothers were supplemented with 0, 1, 2 or 3 mg pyridoxine.HCl (PN.HCl)/d during pregnancy. Maternal PN.HCl supplementations were positively correlated to both maternal (r = 0.62) and cord (r = 0.78) plasma PLP concentrations (p < 0.0001). Mothers supplemented with 2 or 3 mg/d PN.HCl had significantly higher plasma concentrations of PLP and total B6 aldehyde vitamer in maternal and cord blood compared with those receiving 0 or 1 mg PN.HCl/d. A growth benefit for neonates whose mothers had maternal and cord plasma PLP concentrations > or = 40 nM was revealed by the maternal supplementation of 2 mg PN.HCl/d during pregnancy. Thus, in healthy pregnant women, according to our study, a daily supplement of 2 mg PN.HCl provides the adequacy of maternal and neonatal vitamin B6 status and the satisfactory growth of neonates at birth.

Dietary Supplements↗

PubMed1999

Vitamin B6 down-regulates the expression of human GPIIb gene.

Glycoprotein IIb (GPIIb) is the alpha-subunit of the platelet membrane receptor GPIIb/IIIa, which plays a major role in platelet aggregation. Vitamin B6 has been reported to be an antiaggregative agent, although its mechanism is not well known. To understand the molecular mechanism of vitamin B6 on antiaggregation, we analyzed the effects of various forms of vitamin B6 on the expression of human GPIIb promoter using chloramphenicol acetyl transferase (CAT) as the reporter gene. The GPIIb promoter region was amplified by polymerase chain reaction (PCR), cloned into pBLCAT3 to drive the CAT reporter gene and transfected into human erythroleukemia (HEL) cells. Transient expression of the GPIIb promoter was determined after transfected cells were treated with 1 microM pyridoxine (PN), pyridoxal (PL), pyridoxal-5-phosphate (PLP), or 4-deoxypyridoxine (4-dex) for 48 h. Our results show that the GPIIb promoter activity was down-regulated to 54, 35 and 63% in the presence of PN, PL and PLP, respectively, as compared to an untreated control whose promoter activity was 100%. However, no adverse effect on GPIIb promoter was detected by 4-dex, which is an antagonist of vitamin B6. The down-regulation effect of vitamin B6 on GPIIb promoter activity may lead to a reduction of GPIIb protein expression and thus be detrimental to platelet aggregation.

Chloramphenicol O-Acetyltransferase↗

PubMed1999

Identification of a new single nucleotide substitution on the hypoxanthine-guanine phosphoribosyltransferase gene (HPRT(Tsou) from a Taiwanese aboriginal family with severe gout.

OBJECTIVE: A new single nucleotide change of the hypoxanthine-guanine phosphoribosyltransferase (HPRT) gene on coding region has been identified from a Taiwanese aboriginal family with gout. The mutation was used to screen 27 members of the family, 22 Tsou, 70 Atayal, and 76 Bunun children, the elders for whom had been found to have a high prevalence of gout. METHODS: An entire peptide of HPRT coding region was directly sequenced from the cDNA of a patient with severe gout, and by using polymerase chain reaction and restriction fragment length polymorphism to screen the other participants. RESULTS: A new nucleotide change located at nucleotide 152 (G to A transition) was found that predicted an arginine to glutamine substitution at amino acid 51. This variant was named HPRT(Tsou), and was found in 3 women and 3 men among the patient's 7 siblings, 2 boys and 2 girls among the 8 children of the siblings, and one female Tsou (4.5%, 1/22) and one female Atayal (1.4%, 1/70). The serum uric acid concentration among male HPRT(Tsou) carriers in the patient's family was significantly higher than among those who had at least one HPRT gene that did not have HPRT(Tsou). CONCLUSION: We found that the HPRT(Tsou) gene variant is partially responsible for the hyperuricemia in an aboriginal population in Taiwan known for a high incidence of gout.

Adolescent↗