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Biomedical subjects

S H Chang

Publications and source records attributed to S H Chang.

At least 73 records · Page 4Linked to original sources
PubMed2000

Effects of caffeic acid, chlorogenic acid and ferulic acid on growth and arylamine N-acetyltransferase activity in Shigella sonnei (group D).

Arylamine N-acetyltransferase (NAT) activities with 2-aminofluorene (2-AF) as substrates were determined in Shigella sonnei (group D) collected from patients with diarrhoeal disease. The NAT activity was determined using an acetyl CoA recycling assay and high pressure liquid chromatography. Inhibition of growth studies from S. sonnei (group D) demonstrated that caffeic acid (CA), chlorogenic acid (CGA) and ferulic acid (FA) elicited a dose-dependent bactericidal effect in S. sonnei (group D) cultures, i.e. the greater the concentration of CA, CGA and FA, the greater the inhibition of growth of S. sonnei (group D). Cytosols or suspensions of S. sonnei (group D) with and without selected concentrations of CA, CGA and FA co-treatment showed different percentages of 2-AF acetylation. The data indicated that there was reduced NAT activity associated with increased CA, CGA and FA in Shigella dysenteriae (group D) cytosols and intact cells. For the cytosol and intact bacteria examinations, the apparent values of K(m) and Vmax decreased after being co-treated with 400 microM CA, CGA and FA. This report is the first demonstration of plant phenolic inhibition (CA, CGA and FA) of arylamine NAT activity and growth in the bacterium S. sonnei (group D).

Arylamine N-Acetyltransferase↗
PubMed1999

HIV-1 Nef plays an essential role in two independent processes in CD4 down-regulation: dissociation of the CD4-p56(lck) complex and targeting of CD4 to lysosomes.

Human immunodeficiency virus type 1 (HIV-1) Nef down-regulates CD4 by triggering rapid endocytosis of cell surface CD4. To better understand how Nef induces CD4 down-regulation, we generated a series of Nef mutants with small in-frame deletions in the coding region. Three classes of mutants were obtained. The first class produces neither CD4 down-regulation nor dissociation of the CD4-p56(lck) complex. The second class induces CD4 down-regulation in cells lacking p56(lck) expression, but not in cells with p56(lck);these mutants fail to dissociate CD4 from p56lck. These results show that Nef-mediated CD4 dissociation from p56(lck) is important for CD4 down-regulation. The third class of mutants is able to dissociate the CD4-p56(lck) complex but fails to down-regulate surface CD4; internalized CD4 molecules are recycled back to the cell surface. This result suggests that Nef diverts the CD4 recycling pathway to a degradative pathway. We also demonstrate that Nef associates with phosphatidylinositol-3-kinase (PI3K) activity, which is known to be involved in several aspects of membrane trafficking. However, Nef mutants that cause internalized CD4 to be recycled do not associate with PI3K activity; thus Nef-associated PI3K activity might be involved in the latter process of targeting CD4 to a degradative pathway. We conclude that HIV-1 Nef plays a critical role in multiple processes in CD4 down-regulation: (i) disrupting the CD4-p56(lck) complex on the cell surface to allow CD4 internalization and (ii) diverting the internalized CD4 to a lysosomal pathway for its degradation, likely through a PI3K activity.

CD4 Antigens↗
PubMed1999

Pseudorabies virus early protein 0 trans-activates the TATA-associated promoter by stimulating the transcription initiation.

Pseudorabies virus (PRV) early protein 0 (EP0) is a transactivator containing a RING finger domain. To assess the transactivation mechanism of PRV EP0, we performed the in vitro transcription by combining HeLa nuclear extract, purified recombinant EP0 and simple promoter constructs, and evaluated the results by primer extension. The data showed that EP0 could significantly activate the TATA-containing synthetic promoters. Moreover, EP0 activated transcription by stabilizing the formation of transcription initiation complex instead of enhancing the elongation rate. To further understand the role of EP0 on assembling the transcription initiation complex, we performed the pull-down assay using affinity precipitation of proteins from HeLa nuclear extracts and bacterially expressed glutathione-S-transferase EP0 RING finger fusion. The data showed that at least six nuclear proteins physically interacted with the EP0 RING finger. Overall, the transactivation of PRV EP0 is accomplished by enhancing the transcription initiation and is associated with at least six nuclear proteins.

Amino Acid Sequence↗
PubMed1999

Roles of atypical protein kinase C in lysophosphatidic acid-induced type II adenylyl cyclase activation in RAW 264.7 macrophages.

1 Lysophosphatidic acid (LPA) has been widely studied as a naturally occurring and multifunctional phospholipid messenger in diverse tissue and cell types and shown to inhibit adenylyl cyclase (AC) by a G protein-mediated mechanism. 2 In type II AC-expressing mouse RAW 264.7 macrophages, we showed that LPA at 3-50 microM increased cyclic AMP formation in a concentration-dependent manner, the effect being additive with that of forskolin or cholera toxin, and synergistic with that of prostaglandin E1 (PGE1) or isoproterenol. 3 The potentiation effect of LPA was unaffected by the removal of serum or pertussis toxin treatment. 4 Both colchicine and cytochalasin B potentiated the cyclic AMP response to PGE1, the effect being additive to that of LPA. 5 On studying the regulation of type II AC by protein kinase C (PKC), phorbol 12-myristate-13 acetate (PMA) potentiated the PGE1-elicited cyclic AMP response, this effect being non-additive to that of LPA, suggesting that PKC activation was the common mechanism involved in AC potentiation by LPA and PMA. 6 PKC inhibitor Ro 31-8220, but not Go 6976, significantly inhibited the LPA-induced cyclic AMP potentiation. 7 The potentiation effect of LPA was unaffected by long-term treatment with PMA, which resulted in the down-regulation of PKCalpha, betaI, betaII and PKCdelta, but not PKCepsilon, mu, lambda and zeta. 8 By in situ kinase assay, we found a marked increase in atypical PKC activity after LPA treatment. 9 Taken together, we conclude that LPA can elicit a unique signalling cascade in RAW 264.7 macrophages and increase type II AC activity via the activation of atypical PKC.

Adenylate Cyclase Toxin↗
PubMed1999

Nasal-type T/natural killer cell angiocentric lymphoma, Epstein-Barr virus-associated, and showing clonal T-cell receptor gamma gene rearrangement.

Nasal-type T/natural killer (NK) cell lymphoma, which often shows an angiocentric growth pattern, is a distinct clinicopathological entity highly associated with the Epstein-Barr virus (EBV). This tumour has a characteristic immunophenotype, whereas the cytological spectrum is broad. It is known that a clonal T-cell receptor (TCR) gene rearrangement is not found in this tumour. However, it is still unresolved as to whether the finding of a clonal TCR gene rearrangement excludes the diagnosis of nasal-type T/NK cell lymphoma. We describe a case of nasal-type T/NK cell angiocentric lymphoma, EBV-associated, and showing clonal TCR gamma gene rearrangement. The patient died of sepsis 5 months after diagnosis in spite of aggressive chemotherapy.

Adult↗
PubMed1999

Giant congenital multiple patch-like glomus tumors.

Glomus tumors can be classified into solitary and multiple glomus tumors. Congenital multiple glomus tumors are extremely rare, and only 12 cases have been reported in the world literature. We describe the first case with giant congenital multiple patch-like glomus tumors that show partial atrophy.

Actins↗
PubMed1999

Developmental expression of violaxanthin de-epoxidase in leaves of tobacco growing under high and low light.

Violaxanthin de-epoxidase (VDE) is a lumen-localized enzyme that catalyzes the de-epoxidation of violaxanthin in the thylakoid membrane upon formation of a transthylakoid pH gradient. We investigated the developmental expression of VDE in leaves of mature tobacco (Nicotiana tabacum) plants grown under high-light conditions (in the field) and low-light conditions (in a growth chamber). The difference in light conditions was evident by the increased pool size (violaxanthin + antheraxanthin + zeaxanthin, VAZ) throughout leaf development in field-grown plants. VDE activity based on chlorophyll or leaf area was low in the youngest leaves, with the levels increasing with increasing leaf age in both high- and low-light-grown plants. However, in high-light-grown plants, the younger leaves in early leaf expansion showed a more rapid increase in VDE activity and maintained higher levels of VDE transcript in more leaves, indicating that high light may induce greater levels of VDE. VDE transcript levels decreased substantially in leaves of mid-leaf expansion, while the levels of enzyme continued to increase, suggesting that the VDE enzyme does not turn over rapidly. The level of VDE changed in an inverse, nonlinear relationship with respect to the VAZ pool, suggesting that enzyme levels could be indirectly regulated by the VAZ pool.

Chlorophyll↗
PubMed1999

Eruptive vellus hair cyst in a patient with pachyonychia congenita.

Pachyonychia congenita is characterized by symmetrical nail dystrophy, palmoplantar keratoderma, oral leukokeratosis, and follicular hyperkeratosis. In addition to these features, multiple cutaneous cysts of various kinds have been described. We report a case of pachyonychia congenita associated with eruptive vellus hair cyst.

Adult↗
PubMed1999

[The relationships between the elderly loneliness and its factors of personal attributes, perceived health status and social support].

The purpose of this study were to investigate the level of loneliness in elderly people and to explore relationships between loneliness and personal attributes, perceived health status and social support. Purposive sampling was used to recruit clients over 65 years of age from an outpatient department of the Municipal hospital and a senior citizen center in Kaohsiung city, and totaled 120 elderly people had participated in this study. Data were collected by a structured questionnaire which included the UCLA Loneliness Scale, Perceived Health Status Scale, and Social Support Scale. The results revealed the following: 1. The mean score was 38.4 (SD 9.6); level of loneliness in elderly people was moderate, and people who were male, uneducated, unsatisfied with living circumstance, unsatisfied with economic situation, and not attending social groups were more likely to have higher scores of loneliness. 2. There was a significantly negative correlation between perceived health status, mental health, health satisfaction, social support, supportive satisfaction and loneliness. 3. The results of multiple regression found that family interactions, attending social groups and supportive satisfaction were the significant predicting variables of loneliness, and "supportive satisfaction" was the most powerful predictor. Results generated from this study may act as references for mental health care for elderly people.

Aged↗
PubMed1999

Purification and characterization of an arylamine N-acetyltransferase from Lactobacillus acidophilus.

N-acetyltransferase from Lactobacillus acidophilus was purified by ultrafiltration, DEAE-Sephacel, gel filtration chromatography on Sephadex G-100, and DEAE-5pw on high performance liquid chromatography, as judged by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) on a 12% (w/v) slab gel. The purified enzyme was thermostable at 37 degrees C for 1 h with a half-life of 32 min at 37 degrees C, and displayed optimum activity at 37 degrees C and pH 7.0. The K(m) and Vmax values for 2-aminofluorene were 0.842 mM and 2.406 nmol/min/mg protein, respectively. Among a series of divalent cations and salts, Zn2+, Ca2+, Fe2+, Mg2+, and Cu2+ were demonstrated to be the most potent inhibitors. The enzyme had a molecular mass of 44.9 kD. The three chemical modification agents, iodoacetamide, phenylglyoxal, and diethylpyrocarbonate, all exhibited dose-, time-, and temperature-dependent inhibition effects. Preincubation of purified N-acetyltransferase with acetyl coenzyme A (AcCoA) provided significant protection against the inhibition of iodoacetamide and diethylpyrocarbonate, but only partial protection against the inhibition of phenylglyoxal. These results indicate that cysteine, histidine, and arginine residues are essential for this bacterial activity, and the first two are likely to reside on the AcCoA binding site, but the arginine residue may be located close to the AcCoA binding site. This report is the first demonstration of acetyl CoA:arylamine N-acetyltransferase in L. acidophilus.

Arylamine N-Acetyltransferase↗
PubMed1999

Comparison of rocuronium and vecuronium pretreatment for prevention of fasciculations, myalgia and biochemical changes following succinylcholine administration.

BACKGROUND: The purpose of this study was to assess the effect of rocuronium pretreatment on the succinylcholine-induced fasciculations, myalgia and biochemical changes, and to compare it with vecuronium pretreatment. METHODS: We have studied 60 female patients undergoing minor elective surgery, in a prospective double blinded method. Three groups of 20 patients each was pretreated with either saline (control group), rocuronium 0.05 mg/kg (rocuronium group) or vecuronium 0.007 mg/kg (vecuronium group). Three min after the pretreatment, 1.5 mg/kg succinylcholine was injected. Single twitch responses to electrical stimulation were measured. Serum potassium and creatine kinase were respectively measured 5 min after succinylcholine and 24 h after operation. Fasciculations and myalgia on postoperative day 1 and day 2 were evaluated. RESULTS: The incidence of fasciculations was lowest in the rocuronium group, followed by the vecuronium group, and was highest in the control group. The incidence of myalgia on postoperative day 1 was lower in the rocuronium and vecuronium groups than the control group. The increase of serum creatine kinase was similar among the three groups, but there was no increase in serum potassium concentration in any group. No differences of the single twitch responses to electrical stimulation were found between the rocuronium and vecuronium groups. CONCLUSIONS: Rocuronium pretreatment was more effective in reducing fasciculations than was vecuronium pretreatment, but both were equally effective in preventing myalgia on postoperative day 1. This difference may reflect the differential activities of rocuronium and vecuronium at the neuromuscular junction. The increase of creatine kinase was not attenuated by any regimen.

Adult↗
PubMed1998

Left ventricular filling profiles and angiotensin system activity in elite baseball players.

UNLABELLED: Left ventricular (LV) filling profiles in elite baseball players has not been reported in the literature. Also, angiotensin system activity in athletes has never been reported. We used echocardiography to compare 20 male elite baseball players (aged 21.9+/-1.0 years) with those of age- and sex-matched healthy sedentary subjects. Compared with the normal group, the athlete group showed a significant increase in LV mass, LV diastolic and systolic dimension, and left atrial dimension (P<0.05, <0.001, <0.001, and <0.001, respectively). No differences in relative wall thickness or fractional shortening were found between these two groups. Diastolic filling profiles, including peak early diastolic filling velocity (E), peak late diastolic filling velocity (A), E:A ratio, early time-velocity integral (Ei), atrial time-velocity integral (Ai), Ei:Ai ratio, early filling time, deceleration time of early filling, and isovolumic relaxation time, were similar in both groups. Angiotensin system activity, including plasma renin activity, plasma aldosterone, and 24-h urinary aldosterone excretion, showed no difference between these two groups. CONCLUSION: This study suggests that normal LV filling profile, which is mediated partly by normal angiotensin system activity, is not related to increase in LV dimension and mass in elite baseball players.

Adult↗
PubMed1998

Cloning and analysis of the Epstein-Barr virus glycoprotein 350 genes.

Membrane glycoprotein 350 (gp350) of the Epstein-Barr virus (EBV) is considered as a major target for vaccine development, since the gp350 has been identified as the virus' mediator for receptor interaction and as an inducer of specific in vitro virus-neutralizing antibodies. In an initial attempt to develop an effective DNA vaccine against an EBV infection, gp350 genes were isolated from SNU-20 and SNU-1103 which are the EBV-infected lymphoblastoid cell lines established in Korea. In addition, the nucleotide sequences of the gp350 genes were determined and compared with those of other EBV strains such as B95-8, P3HR-1/AG876 and M81. Sequence analysis showed that similar high degrees of homology between 2 EBV strains derived from African Burkitt's lymphoma, P3HR-1 and AG876, was shown between the gp350 genes isolated from 2 EBV-infected lymphoblastoid cell lines established in Korea. Furthermore, these 2 Korean and 2 African strains displayed nearly identical patterns of sequence variations from B95-8. In addition, the sequence of the isolated gp350 genes, which have been reported to be associated with the biology of EBV infection, is analyzed.

Amino Acid Sequence↗
PubMed1998

Up-regulation of the expression of major histocompatibility complex class I antigens by plasmid DNA transfection in non-hematopoietic cells.

The effect of DNA on the surface expression of major histocompatibility (MHC) class I antigens was examined in non-hematopoietic tumor cell lines. Transfection with plasmid DNA via liposome or electroporation significantly increased the surface expression of MHC class I molecules in a transient manner. Northern blot analysis showed that levels of MHC class I mRNA were increased by DNA transfection, probably via transcriptional activation. In contrast, the expression of the MHC class II and beta-actin genes was not affected, suggesting that the up-regulation of MHC class I expression by plasmid DNA works in a gene-specific manner.

Actins↗
PubMed1998

Protein kinase C regulates chondrogenesis of mesenchymes via mitogen-activated protein kinase signaling.

A possible regulatory mechanism of protein kinase C (PKC) in the chondrogenesis of chick limb bud mesenchymes has been investigated. Inhibition or down-regulation of PKC resulted in the activation of a mitogen-activated protein kinase subtype Erk-1 and the inhibition of chondrogenesis. On the other hand, inhibition of Erk-1 with PD98059 enhanced chondrogenesis and relieved PKC-induced blockage of chondrogenesis. Erk-1 inhibition, however, did not affect expression and subcellular distribution of PKC isoforms expressed in mesenchymes nor cell proliferation. The results suggest that PKC regulates chondrogenesis by modulating Erk-1 activity. Inhibition or depletion of PKC inhibited proliferation of chondrogenic competent cells, and Erk-1 inhibition did not affect PKC modulation of cell proliferation. However, PKC-induced modulation of expression of cell adhesion molecules involved in precartilage condensation was reversed by the inhibition of Erk-1. Expression of N-cadherin was detected at the early period of chondrogenesis. Inhibition or depletion of PKC induced sustained expression of N-cadherin, and Erk-1 inhibition blocked the effects of PKC modulation. The expression of integrin alpha5 beta1 and fibronectin was found to be increased transiently during chondrogenesis. Depletion or inhibition of PKC caused a continuous increase of the expression of these molecules throughout the culture period, and Erk-1 inhibition abolished the modulating effects of PKC. Because reduction of the examined cell adhesion molecule expression is a prerequisite for the progression of chondrogenesis after cell condensation, our results indicate that PKC regulates chondrogenesis by modulating expression of these molecules via Erk-1 signaling.

Animals↗
PubMed1998

Regulation of chondrogenic differentiation of mesenchymes by protein kinase C alpha.

Chondrogenesis of chick limb bud mesenchymes requires the expression and activation of protein kinase C (PKC). This study was performed to identify PKC isoform(s) involved in the regulation chondrogenic differentiation of mesenchymes. Multiple PKC isoforms including alpha, epsilon, zeta and lambda/iota were expressed in mesenchymes derived from chick limb buds. Among the expressed PKC isoforms, the levels of PKC alpha and epsilon were increased during chondrogenic differentiation of mesenchymes. The increase in the expression of these isoforms is more evident in the particulate membrane fraction compared with the cytosolic fraction. Chondrogenesis was blocked by either selective inhibition or down-regulation of PKC alpha. In addition, the degree of chondrogenesis was closely correlated with the expression levels of PKC alpha but not other PKC isoforms expressed in mesenchymes. Thus, the results indicate that only PKC alpha is required for the induction of chondrogenic differentiation

Animals↗
PubMed1998

Social desirability and the clinical self-report inventory: methodological reconsideration.

This study assesses how social desirability affects responses in clinical self-report inventories. Six hundred items gathered from four normal personality questionnaires were adapted to devise a pre-experimental personality questionnaire (pre-EMHQ). Results obtained from administering Ko's Mental Health Questionnaire (KMHQ) and the pre-EMHQ to separate samples were the proportion of individuals answering "true" to each item (i.e., P(t)) and the social desirability scale value (i.e., SDSV) of each item. The Experimental Mental Health Questionnaire (EMHQ) was established from the pre-EMHQ by closely matching the P(t)s and the SDSVs of the two questionnaires. Administering the KMHQ and the EMHQ concurrently to another sample provided results for factor analysis and other statistical analyses. The SDSVs and the P(t)s for each of the KMHQ items certainly displayed a linearly increasing relation. The two sets of corresponding subscales also correlated significantly. By applying the polynomial regression analysis, the tendency to score might be expressed as a quadratic function of SDSVs. Two iterative principal-factor analyses of the two sets of subscales each resulted in two factors, and Factor 1 is similar in both the KMHQ and the EMHQ. In brief, social desirability plays a critical role in affecting responses in a clinical self-report inventory. The factors involved and suggestions proposed will be of value for further research.

Adolescent↗