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Biomedical subjects

S M Wang

Publications and source records attributed to S M Wang.

At least 73 records · Page 4Linked to original sources
PubMed1999

Hypermethylation of the p16 gene in sporadic T3N0M0 stage colorectal cancers: association with DNA replication error and shorter survival.

Hypermethylation in the promoter region of the p16 gene was suspected to be involved in the tumorigenesis of colorectal cancers, although its clinical and biological significance remains obscure. In this study, we collected 84 T3N0M0 stage primary colorectal cancers that were curatively resected. The clinicopathologic data were reviewed. p16 hypermethylation was determined by a methylation-specific polymerase chain reaction (PCR). p53 overexpression was detected by immunocytochemistry (ICC). The point mutations in the 12 and 13 codons of the K-ras gene were screened by restriction enzyme analysis. Loss of heterozygosity (LOH) of the DCC (Deleted in Colorectal cancer) gene was examined by PCR using primers of the DCC (18q21) microsatellite marker. The DNA replication error (RER) was examined using 7 microsatellite markers at distinct chromosomal loci. p16 hypermethylation, regarded as an indication of p16 inactivation, was evident in 24 (28.6%) of the tumors. No correlation was found between p16 hypermethylation and various clinicopathologic factors, includinig age, sex, tumor location, tumor size, growth pattern, tumor differentiation, mucin production, vascular and/or lymphatic invasion, lymphocyte infiltration of the tumor, and serum level of carcinoembryonic antigen. There was no association between p16 hypermethylation of K-ras gene mutation, p53 overexpression and LOH of the DCC gene. However, p16 hypermethylation was significantly associated with DNA RER (p = 0.01). Survival analysis revealed a significant survival disadvantage of p16-hypermethylated versus non-p16-hypermethylated tumors (p = 0.0001). These findings indicate that p16 hypermethylation plays a role in the carcinogenesis of a subset of colorectal cancers; and the presence of p16 hypermethylation predicts shorter survival in T3N0M0 stage colorectal cancers.

Aged↗
PubMed1999

A method for the quantitative analysis of human heat shock gene expression using a multiplex RT-PCR assay.

A quantitative multiplex RT-PCR assay is described to measure the levels of messenger RNAs for eight human genes encoding the heat shock proteins (HSP) and molecular chaperones hsp90alpha, hsp90beta, hsp70, hsc70, mtHsp75, Grp78 (BiP), hsp60 and hsp27. The basis of this assay is reverse transcription of total RNA isolated from human cells followed by amplification with PCR. By the careful selection of pairs of oligonucleotide primers corresponding to unique regions of each heat shock gene, selectivity can be attained such that messenger RNAs of multiple heat shock genes can be analyzed simultaneously in a single reaction. This method provides both the absolute and relative levels of each heat shock message by including in the reaction, reference control RNAs corresponding to in vitro transcripts of heat shock gene plasmids carrying small internal deletions.

Cell Line↗
PubMed1999

CFEOM3: a new extraocular congenital fibrosis syndrome that maps to 16q24.2-q24.3.

PURPOSE: To define the clinical characteristics and determine the gene localization for a previously undescribed form of congenital fibrosis of the extraocular muscles (CFEOM), referred to as CFEOM type 3 (CFEOM3). METHODS: A large family with CFEOM was identified, and participating individuals underwent ophthalmologic examination and donated blood for genetic analysis. The family's disorder was tested for linkage to the known CFEOM loci, followed by a genome-wide search and linkage refinement using polymorphic DNA markers. RESULTS: Thirty-eight members of this Canadian family participated in the study. Affected individuals are born with a nonprogressive eye movement disorder characterized by variable expression of ptosis and restrictive external ophthalmoplegia. Severely affected individuals have ptosis, primary gaze fixed in a hypo- and exotropic position, and marked restriction of eye movement bilaterally. Mildly affected individuals have normally positioned globes with a limitation of vertical gaze. Moderately affected individuals have asymmetrical involvement with one eye severely and one eye mildly affected. The disorder is autosomal dominant with variable expression and probable incomplete penetrance. Genetic analysis reveals linkage to markers on 16q24.2q24.3. A maximum lod score of 5.8 occurs at markers D16S3063 and D16S689, and the CFEOM3 disease gene is located within a 5.6-cM region flanked by D16S486 and D16S671. CONCLUSIONS: These data establish that CFEOM3 is a phenotypically variant and genotypically distinct form of CFEOM with linkage to chromosome 16qter. The authors have previously demonstrated that CFEOM1 results from a developmental absence of the superior division of the oculomotor nerve. The authors hypothesize that CFEOM3 results from a defect analogous to, but distinct from CFEOM1.

Blepharoptosis↗
PubMed1999

Staphylococcus capitis bacteremia of very low birth weight premature infants at neonatal intensive care units: clinical significance and antimicrobial susceptibility.

Coagulase-negative staphylococci (CNS) are frequently isolated from blood cultures in critically ill neonates. However, Staphylococcus capitis is rarely reported as a pathogen in human beings. From January, 1995 to December, 1997 at a tertiary care neonatal intensive care unit (NICU), a total of 147 (62%) CNS isolates were detected from 236 positive blood cultures, including 27 isolates of S. capitis. Among the S. capitis bacteremia, 17 isolates were judged to be infections as opposed to 10 of the noninfection cultures. The occurrence of S. capitis infection was correlated with long hospital stay (52 +/- 17.6 days vs. 28 +/- 18.5 days, p=0.003) and total parenteral nutrition administration (46 +/- 17.4 days vs. 22 +/- 19.1 days, p=0.006). Apnea, bradycardia, temperature instability and poor activity were the predominant clinical features. Among the 17 episodes of bacteremia, one patient had complicated septic meningitis. There is no statistical significance between S. capitis infection and the duration of a central venous catheter placement (37 +/- 17.5 days vs. 26 +/- 19.5 days, p=0.165). No catheter related infection was proven. Removal of a percutaneous central venous catheter routinely in patients with S. capitis bacteremia is not recommended. All the patients survived after antibiotic treatment. The prevalence rate of multiple resistant S. capitis was 94%. All isolates were resistant to oxacillin, erythromycin and clindamycin but susceptible to ampicillin/sulbactam, vancomycin and teicoplanin. Empiric therapy for S. capitis infection in NICU with ampicillin/sulbactam is therefore recommended. It is important to detect S. capitis which has a high degree of antibiotic resistance in order to treat the patient correctly. S. capitis should be included as etiology and the possibility of nosocomial outbreak in very low birth weight (VLBW) premature infants at NICU.

Bacteremia↗
PubMed1998

Role of M-line proteins in sarcomeric titin assembly during cardiac myofibrillogenesis.

A rat polyclonal anti-M-line protein antiserum and three mouse monoclonal anti-titin antibodies (E2, F3, and A12) were used to study the spatiotemporal relationship between M-line proteins and titin during myofibril assembly in cultured chicken cardiomyocytes by immunofluorescence microscopy. In day 2 cultures, M-line proteins and titin were detected as punctate staining in most cardiomyocytes, which possessed many nonstriated fibrils. At a late stage (day 3 cultures), M-line proteins were incorporated into dot-like structures along nonstriated fibrils, while titin staining was continuous on these structures. As development progressed, M-line proteins were registered in periodic pattern in the mid-A band. In cardiomyocytes from day 5 cultures, the titin bands were separated by an unstained region, and achieved their adult doublet pattern. Thus, the organization of titin in the sarcomere appears to occur later than that of M-line proteins in the M-line. Our morphological data indicate that the early registration of M-line proteins in primitive myofibrils may guide titin filament alignment via interaction between M-line proteins and titin. In order to investigate the role of M-line proteins in the assembly of titin filaments, anti-M-line protein or anti-titin antibodies were introduced into cultured cardiomyocytes by electroporation to functionally bind the respective proteins, and the profile of myofibril assembly was examined. Cardiomyocytes from day 2-3 cultures with incorporated anti-M-line protein antibodies became shrunk, and exhibited defective myofibrillar assembly, as shown by the failure of titin to assemble into a typical sarcomeric pattern. Incorporation of anti-titin antibody E2, which recognizes the M-line end domain of titin, resulted in the failure of M-line proteins organized into the M-line structure, as shown by random, sporadic staining with anti-M-line protein antibody. These studies confirm the essential role of M-line proteins in the organization of titin filaments in the sarcomere and that the interaction between titin and M-line proteins is crucial to the formation of the M-line structure.

Animals↗
PubMed1998

Coexistence of glutamate and acetylcholine in the developing motoneurons.

Glutamate receptors mediate excitatory neurotransmission in the central nervous systems and are important in neuronal development, acquisition of memory, and are related to some neurodegenerative disorders. In the current study, co-cultures of spinal neurons and myotomal muscle cells were prepared from 1-day-old Xenopus embryo. Spontaneous synaptic currents were recorded from innervated myocytes using whole-cell recording. Local perfusion of glutamate receptor agonists, N-methyl-D-aspartate (NMDA) and non-NMDA, at synaptic regions with another micropipette all increased the frequency of spontaneous synaptic currents. Whole-cell recording was also made in the nerve growth cone of cultured spinal neurons. Local application of glutamate, NMDA or kainate all induced an inward current, indicating the coexistence of NMDA and non-NMDA receptors in the nerve terminals of developing motoneurons. Some innervated myocytes contracted spontaneously in the cultures, which were processed for glutamate immunocytochemistry after the recording of spontaneous synaptic currents. Glutamate immunoreactivity appeared in neuronal varicosities and neuromuscular junctions, indicating that glutamate is co-stored with acetylcholine in motoneurons. Double staining for glutamate and choline acetyltransferase further provides the evidence of the colocalization of glutamate and acetylcholine in developing motoneurons. These results suggest that both NMDA and non-NMDA receptors exist in the nerve terminals of developing motoneurons. Furthermore, glutamate and acetylcholine coexist in the motoneurons. The presynaptic glutamate receptors may thus have a physiological role in neuromuscular synaptogenesis in early embryonic stages.

Acetylcholine↗
PubMed1998

A strategy for genome-wide gene analysis: integrated procedure for gene identification.

We have developed a technique called the Integrated Procedure for Gene Identification that modifies and integrates parts from several existing techniques to increase the efficiency for genome-wide gene identification. The procedure has the following features: (i) Only the 3' portion of the expressed templates is used to ensure a match to 3' expressed sequence tag (EST) sequences; (ii) the 3' portion of the cDNA is poly dA/poly dT minus, which maintains complete representation of the expressed copies, particularly the rare copies, which otherwise would be lost heavily because of random poly dA/poly dT hybridization in the subtraction reaction; (iii) redundancy is decreased substantially by the subtraction reaction to reduce the effort for sequencing analysis; (iv) the nonsubtracted templates that largely contain the rare copies are amplified selectively with suppression PCR and are sequenced directly or through serial analysis of gene expression (SAGE); and (v) the identified sequences are matched to databases to determine whether they are cloned genes, ESTs, or novel sequences. Using this procedure in a model system, we showed that the redundant copies were largely removed, and the rates of EST matches and the novel sequence identification were significantly increased. Most of the plasmids containing the matched EST are readily available from the IMAGE consortium. This technique can be used to index genome-wide expressed genes and to identify differentially expressed genes in different cells. Compared with the existing techniques, this procedure is relatively efficient, simple, less expensive, and labor intensive. It is especially useful for standard molecular laboratories to perform genome-wide studies.

Base Sequence↗
PubMed1998

Distribution of the cadherin-catenin complex in normal human thyroid epithelium and a thyroid carcinoma cell line.

E-cadherin is the major cell-cell adhesion molecule expressed by epithelial cells. Cadherins form a complex with three cytoplasmic proteins, alpha-, beta-, and gamma-catenin, and the interaction between them is crucial for anchoring the actin cytoskeleton to the intercellular adherens junctions. The invasive behavior of cancer cells has been attributed to a dysfunction of these molecules. In this study, we examined the distribution of the cadherin-catenin complex in a Chinese human thyroid cancer cell line, CGTH W-2, compared with that in normal human thyroid epithelial cells. In the normal cells, using immunofluorescence staining, E-cadherin and alpha-, beta-, and gammm-catenin were found to be localized at the intercellular junction and appeared as 135, 102, 90, and 80 kD proteins on Western blots. In CGTH W-2 cells, no E-cadherin and gamma-catenin immunoreactivity was detected by immunofluorescence or Western blotting; alpha- and beta-catenin were detected as 102 and 90 kD proteins on blots but gave a diffuse cytoplasmic immunofluorescence staining pattern in most cells, while beta-catenin was also distributed throughout the cytoplasm in most cells but was found at the cell junction in some, where it colocalized with alpha-actinin. The present data indicate that the loss of cell adhesiveness in these cancer cells may be due to incomplete assembly of the cadherin-catenin complex at the cell junction. However, this defect did not affect the linkage of actin bundles to vinculin-enriched intercellular junctions.

Actinin↗
PubMed1998

Downregulation and subcellular redistribution of the gamma-aminobutyric acidA receptor induced by tunicamycin in cultured brain neurons.

The significance of N-linked glycosylation and oligosaccharide processing was examined for the expression of gamma-aminobutyric acidA receptor (GABA(A)R) in cultured neurons derived from chick embryo brains. Incubation of cultures with 5 microg/ml of tunicamycin for 24 h blocked the binding of 3H-flunitrazepam and 3H-muscimol, probes for the benzodiazepine and GABA sites on the receptor, by about 20% and 28%, respectively. The loss of ligand binding was due to a reduction in the number of binding sites with no significant changes in receptor affinity. Light microscopic immunocytochemistry also revealed that the treatment reduced approximately 13% of the intensity of GABA(A)R immunoreactivity in the neuronal somata. Furthermore, the fraction of intracellular receptors was decreased to 24% from 34% of control in the presence of the agent, as revealed by trypsinization of cells in situ followed by 3H-flunitrazepam binding. The molecular weight of the receptor subunit protein was lowered around 0.5 kDa after tunicamycin treatment, in accordance with that following N-glycosidase F digestion, indicating the blockade of N-linked glycosylation of GABA(A)R by tunicamycin. Moreover, intense inhibitions of 91% and 44%, respectively, were detected to the general galactosylation and mannosylation in the tunicamycin-treated cells, whereas the protein synthesis was hindered by 13%, through assaying the incorporation of 3H-sugars and 3H-leucine. Nevertheless, treatment with castanospermine or swainsonine (10 microg/ml, 24 h), inhibitors to maturation of oligosaccharides, failed to produce significant changes in the ligand binding. In addition, in situ hybridization analysis showed that these three inhibitors did not perturb the mRNA of GABA(A)Ralpha1-subunit. The data suggest that tunicamycin causes the downregulation and subcellular redistribution of GABA(A)R by producing irregularly glycosylated receptors and modifying their localization. Both galactosylation and mannosylation during the process of N-linked glycosylation may be important for the functional expression and intracellular transport of GABA(A)R.

Animals↗
PubMed1998

Effects of a water-soluble extract of Cordyceps sinensis on steroidogenesis and capsular morphology of lipid droplets in cultured rat adrenocortical cells.

Cordyceps sinensis contains a factor that stimulates corticosteroid production in the animal model. However, it is not known whether this drug acts directly on the adrenal glands or indirectly via the hypothalamus-pituitary axis. In the present study, we used primary rat adrenal cell cultures to investigate the pharmacological function of a water-soluble extract of Cordyceps sinensis (CS) and the signaling pathway involved. Radioimmunoassay of corticosterone indicated that the amount of corticosterone produced by adrenal cells is increased in a positively dose-dependent manner by CS, reaching a maximum at 25 microg/ml. This stimulating effect was seen 1 h after CS treatment and was maintained for up to 24 h. Concomitantly, the lipid droplets in these cells became small and fewer in number. Immunostaining with a monoclonal antibody, A2, a specific marker for the lipid droplet capsule, demonstrated that detachment of the capsule from the lipid droplet occurs in response to CS application and that the period required for decapsulation is inversely related to the concentration of CS applied. The mechanism of CS-induced steroidogenesis is apparently different from that for ACTH, since intracellular cAMP levels were not increased in CS-treated cells. However, combined application with calphostin C, a PKC inhibitor, completely blocked the effect of CS on steroidogenesis, suggesting that activation of PKC may be responsible for the CS-induced steroidogenesis.

Adrenal Cortex↗
PubMed1998

Release of acetylcholine from embryonic myocytes in Xenopus cell cultures.

1. Acetylcholine (ACh) is important as the transmitter responsible for neuromuscular transmission. Here we report the non-quantal release of ACh from embryonic myocytes. 2. Co-cultures of spinal neurons and myotomal muscle cells were prepared from 1-day-old Xenopus embryos. Single channel currents were recorded in the non-innervated myocytes. When the patch pipette was filled with Ringer solution alone, spontaneous single channel currents occurred, which were inhibited by d-tubocurarine (d-Tc). 3. The channel conductance appearing in Ringer solution (37.3 pS) was similar to that of an embryonic-type ACh channel (36.9 pS), indicating that ACh is probably released from myocytes in normal Ringer solution. 4. When the patch pipette was filled with anticholinesterase alone to prevent hydrolysis of ACh released from myocytes, both physostigmine and neostigmine in a concentration-dependent manner increased channel open probability; it was reduced by d-Tc or alpha-bungarotoxin. 5. Vesamicol and quinacrine, vesicular transporter inhibitors, reduced the channel open probability caused by ACh released from myocytes in the presence of neostigmine or physostigmine. 6. Intracellular alkalinization with NH4Cl inhibited the ACh release from myocytes, whereas, extracellular alkalinization, brought about by replacing normal Ringer solution, with pH 8.6 Ringer solution enhanced ACh release. 7. The immunocytochemistry of choline acetyltransferase (ChAT) showed that ChAT exists in both myocytes and neuronal cells but not in fibroblasts. 8. These results suggest that embryonic myocytes are capable of synthesizing and releasing ACh in a non-quantal manner. Extracellular alkalinization enhanced and intracellular alkalinization inhibited ACh release from myocytes.

Acetylcholine↗
PubMed1998

Preoperative sonographic diagnosis of sealed-off perforated gastric ulcer.

Perforated peptic ulcer (PPU) is a common surgical emergency. Early diagnosis and intervention are necessary to reduce the morbidity and mortality. Radiographic or sonographic detection of free air is neither sensitive nor specific for PPU. We report a case of sealed-off PPU with direct sonographic demonstration of the perforation tract within the anterior wall of the gastric antrum. The diagnosis was confirmed at laparotomy.

Helicobacter Infections↗
PubMed1998

Abdominal sonography screening of clinically diagnosed or suspected appendicitis before surgery.

We conducted a prospective study to evaluate the value of abdominal sonography in the diagnosis of acute appendicitis and determine the need for abdominal sonography before operation. Altogether 191 patients with clinically diagnosed or suspected appendicitis underwent an abdominal sonography examination performed by a staff surgeon before operation. The sonographic findings are classified into three categories: appendicitis, other diseases, or normal screening. A total of 158 patients (82.7%) with positive findings of appendicitis proceeded to surgery; 18 patients (9.4%) were found to have other diseases, and they were treated for their conditions; and 15 patients (7.9%) with normal screening were discharged from the hospital and were reevaluated 2 weeks later. Only one patient had a false-negative finding. Of the 158 patients undergoing operation, 143 (90.5%) were proved to have appendicitis by the pathologic reports. A total of 32 negative appendectomies (16.8%) were prevented after sonographic examination. Abdominal sonography for detecting acute appendicitis had a sensitivity of 99.3%, a specificity of 68.1%, an accuracy of 91.6%, a positive predictive value of 90.5%, and a negative predictive value of 97.0%. The value of meticulous history-taking, physical examination, and laboratory tests cannot be overemphasized. Our experience suggests that patients with clinically diagnosed or suspected acute appendicitis should routinely undergo abdominal sonography examination, performed by an experienced surgeon, to further decrease the negative appendectomy rates.

Acute Disease↗
PubMed1998

High rates of antimicrobial resistance among clinical isolates of nontyphoidal Salmonella in Taiwan.

To assess trends in antimicrobial-resistant Salmonella infections from 1989 to 1996 in southern Taiwan, the minimum inhibitory concentrations (MICs) of 14 antibiotics or antibiotic combinations were determined by the agar dilution method for 297 clinical isolates of nontyphoidal Salmonella. The rates of resistance to ampicillin, chloramphenicol, and tetracycline were 65, 67, and 78%, respectively. Resistance to trimethoprim-sulfamethoxazole (TMP-SMX) increased from 25% in 1989-1992 to 35% in 1993-1996 (P=0.057). For new quinolones and extended-spectrum cephalosporins, no resistant strains were encountered. Multiple resistance to more than five antimicrobial drugs doubled from 10.6% in 1989-1992 to 19.7% in 1993-1996. Multiply resistant salmonellae were isolated more commonly from blood samples than from feces (30% vs. 14%, P<0.05). In Taiwan, ampicillin, chloramphenicol, and even TMP-SMX are no longer the drugs of choice for treatment of serious nontyphoidal Salmonella infections. Extended-spectrum cephalosporins are now the preferred drugs in Taiwan for treatment of invasive Salmonella infections in children.

Anti-Bacterial Agents↗
PubMed1998

The Gln-Arg 191 polymorphism of the human paraoxonase gene is not associated with the risk of coronary artery disease among Chinese in Taiwan.

Paraoxonase (PON1) is a high density lipoprotein-associated enzyme capable of hydrolyzing lipid peroxides, and thus, might protect lipoproteins from oxidation. A common polymorphism due to an amino acid substitution (Gln-Arg) at codon 191 is considered to be a major determinant of variation in serum PON1 activity. Recent studies have suggested that the PON1-191 polymorphism is an independent risk factor for coronary atherosclerosis in patients with or without diabetes mellitus. The association of PON1-191 polymorphism genotypes and coronary artery disease (CAD) among Chinese subjects in Taiwan was examined. The genotype of 218 angiographically documented CAD patients and the same number of age- and sex-matched control subjects was determined. Genotypes AA, AB and BB were present in 25 (11%), 102 (47%) and 91 (42%) of control subjects, respectively, and in 30 (14%), 96 (44%) and 92 (42%) of CAD patients, respectively (chi2 = 0.57, P = 0.75 between groups). The frequency of the A allele was 0.36 for the control group and 0.35 for CAD patients (P = 0.94). No significant differences in the PON1-191 genotype frequencies could be found between groups when multivariate logistic regression analysis was performed, or different subgroups of age, sex or risk factors were analyzed. Among control subjects, there was also no significant difference between genotypes of the PON1-191 polymorphism and various clinical and lipid variables. In conclusion, our data suggest that there is no association between the Gln-Arg 191 polymorphism of the human PON1 gene and CAD among Chinese subjects in Taiwan.

Alleles↗
PubMed1998

Fatal coxsackievirus B infection in early infancy characterized by fulminant hepatitis.

OBJECTIVES: to clarify the major features of fatal coxsackievirus B infection characterized by fulminant hepatitis in early infancy. METHODS: clinical manifestations and laboratory investigations concerning five consecutive young infants with overwhelming coxsackievirus B fulminant hepatitis between 1994 and 1997 were retrospectively reviewed. Aetiological diagnosis was made by viral cultures and confirmed by a neutralization test with a type-specific antiserum. RESULTS: all five had a deteriorating clinical course of severe hepatitis complicated by disseminated intravascular coagulopathy (DIC). Coxsackievirus B1 infection was established in four patients and coxsackievirus B3 in one. The pathological findings of the two cases illustrated extensive hepatocellular necrosis. Fulminant hepatitis can occur as a leading presentation of disseminated coxsackievirus B infections and dominant the clinical features in neonates and young infants. CONCLUSIONS: the liver was the target organ of fatal coxsackievirus B infection in our patients. Hepatic involvement progressed rapidly to jaundice and coagulopathy, and was considered to be indicative of poor prognosis. Coxsackievirus B hepatitis may be serious in early infancy.

Coxsackievirus Infections↗
PubMed1998

The impact of National Health Insurance on the volume and severity of emergency department use.

National Health Insurance (NHI) was introduced in Taiwan on March 1, 1995. To evaluate the Influence of NHI on the volume and severity of emergency department (ED) visits, a retrospective analysis was conducted. The results showed that NHI did not result in a substantial increase in ED volume (P > .05), but the severity as measured by triage nurses did increase (P < .01). There was no change in the number of admissions to the intensive care units of patients transferred from smaller hospitals, but its percentage significantly decreased (P < .05), which may be a result of the significant increase in the total number of interhospital transfers. It was hypothesized that the universal coverage and a copayment contributed to these changes.

Emergency Service, Hospital↗