Biomedical subjects

S C Chang

Publications and source records attributed to S C Chang.

At least 235 records · Page 13Linked to original sources

PubMed1993

The sixth Nationwide Tuberculosis Prevalence Survey in Korea, 1990.

SETTING: Nationwide random sample survey for tuberculosis in 1990. OBJECTIVE: To investigate the prevalence of tuberculosis infection, morbidity and drug resistance and BCG coverage, and to compare the findings with those of the previous 5 surveys. DESIGN: The following investigations were performed: tuberculin test, BCG scar screening, chest miniature radiography (70 mm x 70 mm) for those aged over 5 years, sputum direct smear, culture and drug susceptibility test, and a questionnaire to obtain history of chemotherapy and symptoms. RESULTS: The coverage of the investigation has been of more than 95% in each survey. The main findings are as follows: BCG coverage of those aged under 30 and of infants (aged under 1 year) has increased from 24% to 86% and from 1% to 79% respectively. The observed tuberculin positivity (> or = 10 mm in diameter) of subjects aged under 30 has decreased from 45% to 27%. The reduction of positivity was significant in children aged 5-9 years, from 34% to 8%. The annual risk of infection has dropped by over 6% annually. The prevalence of pulmonary tuberculosis per 100,000 has decreased: direct smear-positive from 690-143, smear and/or culture positive from 940-241 and active cases from 5065-1842 respectively. The drug resistance rate had increased to the peak of 47% in 1980, but had decreased to 27% in the last survey. CONCLUSION: The tuberculosis situation has improved significantly in every aspect in the last 25 years.

Adolescent↗

PubMed1993

Ureteroscopic treatment of lower ureteral calculi in the era of extracorporeal shock wave lithotripsy: from a developing country point of view.

In a series of 229 lower ureteral calculi manipulated with either extracorporeal shock wave lithotripsy (ESWL) or ureteroscopy the stone clearance rate 7 days after treatment was 40.6% and 90%, respectively. Only 17 of 32 patients (53.1%) treated with ESWL were rendered stone-free at 4-week followup. In addition to concern about stone clearance, other medical and social factors, and the availability of health insurance coverage must be considered. Since the differences of living standards between highly developed and developing countries are great, the selection of ESWL or ureteroscopy as primary treatment of lower ureteral calculi must be based on the socioeconomical status of a specific country. Because ESWL devices are not readily available in most developing countries and ureteroscopy is cost-effective, highly efficacious (greater than 92%) and involves minimal morbidity (less than 10%) for calculi removal in experienced hands, we recommend ureteroscopy as the treatment of choice for lower ureteral stones, with ESWL as the alternative, in developing countries.

Adult↗

PubMed1993

Secondary metabolites resulting from degradation of PR toxin by Penicillium roqueforti.

PR toxin is a secondary metabolite of the fungus Penicillium roqueforti. It is lethal to rats, mice, and cats. Usually, the amount of PR toxin in the culture medium decreases from its maximum on day 15 to zero within 3 to 4 days. We found that two were secondary metabolites produced in the culture medium of this fungus while the production of PR toxin was decreasing. We isolated and purified the two compounds in pure and colorless crystalline form. On the basis of elemental analysis and mass, 1H and 13C nuclear magnetic resonance, infrared, and UV spectroscopies, the two compounds were identified as PR-imine (C17H21O5N) and PR-amide (C17H21O6N). The structures of both compounds and of PR toxin (C17H20O6) were closely related, and the peak production of PR toxin appeared earlier than those of PR-imine and PR-amide. Moreover, PR toxin was transformed to PR-imine when PR toxin was incubated with the culture medium on a given culture day. Thus, we propose that PR toxin is degraded into PR-imine and PR-amide in the culture medium of P. roqueforti.

Amides↗

PubMed1993

Functional motifs of delta antigen essential for RNA binding and replication of hepatitis delta virus.

The functions of delta antigens (HDAgs) in the replication of hepatitis delta virus (HDV) have been identified previously. The small HDAg acts as a transactivator, whereas the large HDAg has a negative effect on replication. To understand the molecular mechanisms involved in the control of HDV replication, we have established a replication system in Huh-7 cells by cotransfecting a monomeric cDNA genome of HDV and a plasmid encoding the small HDAg. We demonstrate that a leucine repeat in the middle domain of the small HDAg is involved in binding to the HDV genome and transactivation of HDV replication. When the leucine repeat was disrupted by a substitution of valine for leucine at position 115, both RNA-binding and transactivation activity of the small HDAg were abolished. In contrast, the binding and transactivation activities were not affected when Leu-37 and Leu-44 of the small HDAg were replaced by valines. In addition, small and large HDAgs can interact with each other to form protein complexes in vitro. The complex formation that may lead to the trans-dominant negative regulation of large HDAg in HDV replication is mediated by a cryptic signal located between amino acid residues 35 and 65 other than the putative N-terminal leucine zipper motif. Furthermore, an extra 21-amino-acid extension near the N terminus converts the small HDAg into a pseudo-large HDAg with negative regulation activity of HDV replication even though the extreme C-terminal residue is unchanged.

Amino Acid Sequence↗

PubMed1993

Predictive factors for successful surgical outcome of benign prostatic hypertrophy.

Four hundred patients with benign prostatic hypertrophy (BPH) undergoing prostatic surgery were enrolled in this study in order to search for factors predictive of a successful outcome. 139 patients had acute urinary retention and the others had irritative and obstructive voiding symptoms. Preoperative examinations included intravenous urography (IVU), transrectal sonography of the prostate (TRSP), cystometry, uroflowmetry, and urethral pressure profilometry (UPP). Retropubic prostatectomy was undertaken in 16 cases, transurethral resection of the prostate in 335, and transurethral incision of the prostate in 49. In the follow-up period of 3 months to 3 years, a strictly successful result was achieved in 324 patients (81%). 26 patients (6.5%) had a fair result, 30 (7.5%) were stationary, in 18 (4.5%) the symptoms became worse, and 2 (0.5%) died postoperatively. On analysis of the success rate, 9 favorable factors and 9 unfavorable factors were noted. A symptomatic large prostatic adenoma proven by IVU, TRSP, or UPP will imply a higher success rate. Urodynamically obstructive BPH proven by a high voiding pressure and constrictive flow pattern can also predict a satisfactory outcome. The unfavorable factors always come from a small adenoma, uncertain irritative symptoms and detrusor underactivity. Patients with more than 2 unfavorable factors should be investigated carefully before surgery. The presence of 2 favorable factors without an unfavorable factor will usually predict the best surgical outcome.

Aged↗

PubMed1993

Effect of body position on gas exchange in patients with unilateral central airway lesions. Down with the good lung?

In this study, we evaluated the effect of body position (erect, supine, and two decubitus positions) on gas exchange (alveolar-arterial PO2 difference [AaPO2]) in 35 patients who had various degrees of lung collapse roentgenographically caused by unilateral central airway lesions, with special reference to the difference in AaPO2 between two lateral decubitus positions. The patients were divided into two groups. Group 1 was composed of 23 patients with FEV1/FVC > 70 percent. In group 2, there were 12 patients with FEV1/FVC < 70 percent. Our results showed that the mean AaPO2 of group 1 patients was least in the lateral decubitus position with normal lung down (AaPO2N), followed by those in the supine position (AaPO2S), in the lateral decubitus position with lesioned lung down (AaPO2L), and in the erect position (AaPO2E). There was no significant difference in AaPO2 obtained in four positions. However, a significantly negative correlation was found between AaPO2NL (AaPO2N minus AaPO2L) and patient's FEV1 (p < 0.05). In group 2 patients, the mean AaPO2E was least, followed by AaPO2L, AaPO2N, and AaPO2S. The changes of body position did not significantly affect gas exchange in group 2 patients. Unlike previous reports, the present study showed that AaPO2N was not exclusively less than AaPO2L in our patients. AaPO2N was higher than AaPO2L in 11 of 23 in group 1 and in 5 of 12 in group 2 patients. In summary, our results indicated that positional changes did not significantly affect gas exchange in the patients with lung collapse roentgenographically caused by unilateral central airway lesions and the dogma "Down with the good lung" could not be applied to these patients flawlessly.

Aged↗

PubMed1993

Extralobar pulmonary sequestration presenting as an anterior mediastinal tumor in an adult.

Extralobar pulmonary sequestration (EPS) is a rather uncommon congenital anomaly. Most patients are diagnosed in their early life or during the first decade because of the early appearance of symptoms, including feeding difficulty, cyanosis, and dyspnea, or because of symptoms arising from the associated congenital abnormalities. Extralobar pulmonary sequestration is more often found between the lower lobe and the diaphragm and is usually associated with other congenital abnormalities, but the case reported herein differs in these respects. In this report, an incidental finding of EPS is described in a 30-year-old Chinese man, where EPS presents as an anterior mediastinal mass roentgenographically. The mass was attached to the right suprahilar region by a fibrovascular pedicle which contained a small elastic artery, veins, and nerve bundles.

Adult↗

PubMed1993

In vitro antimicrobial activity of fluoroquinolones against clinical isolates obtained in 1989 and 1990.

The in vitro activity of nine fluoroquinolones, enoxacin, norfloxacin, ofloxacin, ciprofloxacin, lomefloxacin, tosufloxacin, sparfloxacin, fleroxacin and levofloxacin, and two earlier quinolones, nalidixic acid and pipemidic acid, against 1,346 bacterial strains isolated clinically between 1989 and 1990, was evaluated by agar dilution method. The bacteria studied were Staphylococcus aureus (including methicillin-susceptible and -resistant strains), Staphylococcus epidermidis, Enterococcus species (including high-level gentamicin-resistant strains), Escherichia coli, Salmonella species, Proteus mirabilis, Proteus vulgaris, Morganella morganii, Klebsiella pneumoniae, Enterobacter cloacae, Serratia marcescens, Citrobacter spp., Pseudomonas aeruginosa, Pseudomonas cepacia, Acinetobacter baumannii, and Bacteroides fragilis. In contrast to the moderate to poor activity of two earlier quinolones, the fluoroquinolones acted well against most Enterobacteriaceae and A. baumannii. The minimum inhibitory concentrations for 90% of the drug strains (MIC90s) were < 1 microgram/mL against most tested species. Ciprofloxacin, tosufloxacin, sparfloxacin, and levofloxacin were more effective against multi-drug-resistant nosocomial pathogens. All fluoroquinolones assayed were very active against methicillin-susceptible S. aureus, with MIC90s < or = 1 microgram/mL. For methicillin-resistant strains, on the other hand, the MIC90s were > or = 4 micrograms/mL. There was no significant difference in fluoroquinolone susceptibility between methicillin-susceptible and -resistant S. epidermidis. Sparfloxacin, tosufloxacin, ciprofloxacin and levofloxacin were more active against enterococci. Most fluoroquinolones were relatively inactive against B. fragilis, with the exception of tosufloxacin, sparfloxacin and levofloxacin. The MIC90s of most quinolones assayed against K. pneumoniae, Citrobacter spp., E. cloacae, S. aureus and S. epidermidis were at least four-fold higher in our study. Therefore, it is important for physicians to use fluoroquinolones carefully so as to prevent or delay the emergence of resistant strains.

Anti-Infective Agents↗

PubMed1993

Antimicrobial susceptibility of enterococci in vitro.

Treating patients with enterococcal infections has become difficult because of the emergence of several resistant traits in the past decade, including high-level resistance to gentamicin, beta-lactamase production, non-beta-lactamase-associated penicillin resistance and vancomycin resistance. To determine the antimicrobial susceptibility and to survey the antibiotic resistance of enterococci, we tested 111 clinical isolates of enterococci from the National Taiwan University Hospital from 1990 to 1991. There were 102 isolates of Enterococcus faecalis, five of Enterococcus faecium, and four of other enterococcal species. All these isolates were tested in vitro by the agar dilution method for determination of the minimal inhibitory concentration (MIC), by the broth microdilution test for screening of high-level resistance to gentamicin and by the rapid chromogenic cephalosporin method for detection of beta-lactamase production. The effect of the combination of two antimicrobial agents against 20 of the 111 isolates, including strains with high-level and low-level resistance to gentamicin, were further checked by the checkerboard titration method. Among 17 antimicrobial agents, the most active agent was ampicillin, followed by vancomycin, ciprofloxacin, ofloxacin and penicillin. Although none included in these were beta-lactamase producers or vancomycin-resistant strains, there was a high proportion (62%) with high-level resistance to gentamicin among our isolates. There were 11 isolates, seven Enterococcus faecalis and four Enterococcus faecium, which had MICs beyond the clinically achievable level of penicillin (MIC > or = 64 micrograms/mL). Because these resistant isolates of enterococci have important therapeutic implications, periodic surveillance and MIC testing are suggested.

Anti-Bacterial Agents↗

PubMed1993

[Lysosomal enzyme activity of cultured fetal cells in Chinese and its clinical application].

Lysosomal storage diseases (LSD) are caused by deficient activity of specific lysosomal enzymes. Early diagnosis and selective termination is still the trend of therapy. The purpose of this study was to establish an assay system and investigate the reference range of lysosomal enzyme activity of cultured fetal cells in the Chinese population. Seventy amniotic fluid and 9 chorionic villi samples were collected and cultured in this study. Enzyme activity assay was done by synthesized 4-Mu-binded substrates. The activity was expressed as nmol/mg protein/hour. In cultured amniotic cells, the results showed 14-138 of alpha-glucosidase, 8-133 of alpha-galactosidase, 32-470 of alpha-mannosidase, 101-1121 of alpha-fucosidase, 106-1321 of beta-galactosidase, 15-268 of beta-glucosidase, 11-279 of beta-glucuronidase, 101-1193 of Hexosaminidase A, and 886-6204 of N-acetyl-alpha-glucosaminidase. In cultured chorionic villi samples, it showed 22-335 of alpha-glucosidase, 31-230 of alpha-galactosidase, 47-250 of alpha-mannosidase, 35-218 of alpha-fucosidase, 49-934 of beta-galactosidase, 34-329, of beta-glucosidase, 57-379 of beta-glucuronidase, and 328-3412 of Hexosaminidase A. The enzyme activity was not correlated with the gestation age when sample was obtained. Furthermore, there was no statistical significance among the range of amniotic cells, chorionic villi samples, skin fibroblasts and peripheral leukocytes for each enzyme studied. It is suggested that the synthesis of lysosomal enzymes has been mature since the early fetal state, and the samples obtained as early as 8 weeks of gestation age can be used for early diagnosis of lysosomal storage diseases.

Cells, Cultured↗

PubMed1993

Extracorporeal shock wave lithotripsy for obstructed proximal ureteral stones. A prospective randomized study comparing in situ, stent bypass and below stone catheter with irrigation strategies.

In an attempt to assess the usefulness of a ureteral stent in facilitating disintegration of obstructed proximal ureteral stone with extracorporeal shock wave lithotripsy (ESWL), a prospective randomized study on 120 patients with ultrasonic evidence of hydronephrosis whose stone sizes were greater than 1.0 x 0.6 cm on KUB film and located above the level of L5 were allocated into three distinct treatment strategies: group 1: in situ without stone manipulation; group 2: bypass stones with stent, and group 3: placement of a catheter below stone with continuous saline irrigation. Of 77 patients, 26, 27 and 24 in each group, followed up for a period of 6 months with sufficient data for analysis, the stone-free rates were 76.9, 59.3 and 62.5%, respectively. The average number of shock waves delivered to accomplish a stone-free state were 3,245, 3,250 and 3,880 for individual groups and the comparisons among them were statistically insignificant (p's > 0.1). ESWL retreatment was common, being 33.3, 29.4 and 43.8%, respectively. Hydronephrosis has a major impact on the outcome of ESWL treatment, as more stone-free cases were found in the mildly hydronephrotic category than in the severer counterparts. About 90% of cases who finally were stone-free, passed all their stone fragments within 28 days. Ancillary procedures were needed in 13 (16.9%), 7 received ureterolithotomy, whilst 6 were removed of their stones by ureteroscopy.

Adult↗

PubMed1993

Cryptococcal infection of the vagina.

BACKGROUND: Cryptococcal infection is opportunistic and occurs most commonly in immunocompromised patients. Meningitis is the most frequent manifestation and causes marked morbidity and mortality. Other sites are less common. We report a case of vaginal cryptococcal infection. CASE: A 72-year-old patient who had undergone resection of the colon for cancer 9 years earlier was noted to have a suspicious lesion on the right vaginal wall after an abnormal Papanicolaou test. Biopsy of the lesion showed findings compatible with cryptococcal infection. Serial examinations revealed no evidence of systemic infection or immunocompromised condition. Empirical treatment was tried with fluconazole. Follow-up colposcopy showed almost complete disappearance of the vaginal lesion, and histologic section and culture of the tissue failed to reveal cryptococcus. CONCLUSION: Cryptococcal infection is rare, especially in a patient with no evidence of an immunocompromised condition. The preliminary result of fluconazole treatment was satisfactory. However, further follow-up and evaluation are needed to confirm the effectiveness of fluconazole in our patient.

Aged↗

PubMed1992

Chromosome analysis in spontaneous pregnancy loss: use of placental villus mesodermal core cell cultures.

Culture of placental villus mesodermal core cells, a method developed for chorionic villus sampling, was used for cytogenetic analysis in 168 spontaneous pregnancy losses. Successful karyotype results were obtained in 72% of cases and 87.5% of cases in which placental tissue was available. Culture of placental villus mesodermal core cells is useful in the evaluation of spontaneous pregnancy loss, particularly when tissues of direct fetal origin are unavailable or unsuitable for culture. Details of culture and specimen handling techniques are provided.

Abortion, Spontaneous↗

PubMed1992

Empirical procedure that uses molecular structure to predict enantioselectivity of chiral stationary phases.

A total of 121 racemic compounds were separated in the normal-phase mode on a (S)-(1-naphthylethyl)carbamoylated beta-cyclodextrin (S-NEC-beta-CD) bonded phase and 74 on the R equivalent (R-NEC) chiral stationary phase (CSP). All compounds are of the type that have four substituents on a stereogenic center, rather than an "axis of chirality". It is shown that the binary solvent pair used as the mobile phase has a significant influence on chiral recognition. However, the proportions of the components of a specific pair have little effect. From the results, the individual contributions to chiral recognition by these CSPs were estimated for 81 different substituents of the stereogenic center. Varying the arrangement of these 81 substituents could produce over 1.6 million compounds. Hydrogen was chosen as the reference substituent and was assigned a 0 cal/mol free energy. The chiral recognition increased when sp2-hybridized carbons were connected to the stereogenic center. Conversely, sp3-hybridized carbons decreased the enantioselectivity. Amido groups increased the chiral recognition, especially when associated with pi-acid (3,5-dinitrobenzoyl) or pi-basic (naphthyl) groups. This approach does not allow one to know which enantiomer elutes first. However, the "substituent energy" list for chiral compounds can be used to obtain an estimated value for the enantioselectivity of a compound by adding the energy contributions of the four substituents connected to the stereogenic center. In this way one can predict a priori whether or not a compound will separate on a CSP and estimate its separation factor (alpha). Theoretically, this approach can be used for most CSPs, provided a sufficient data base is generated on them.

Carbamates↗

PubMed1992

The 16S rRNA gene of Streptomyces lividans TK64 contains internal promoters.

A 632-bp Sau3AI fragment of Streptomyces lividans TK64 genome was found to confer promoter activity in Streptomyces and Escherichia coli. This fragment showed almost identical sequence (97.8%) to the S. coelicolor 16S rRNA segment encompassing from nucleotide 706 to 1337 region. The transcription start points of this fragment were identified by the primer extension method. Analysis of the nucleotide sequence upstream the transcription start points revealed two putative E. coli-like promoters resided within this fragment. The occurrence of internal promoters active in Streptomyces and E. coli was also confirmed in the 16S rRNA gene of rrnE operon from TK64.

Base Sequence↗

PubMed1992

Nuclear localization signals, but not putative leucine zipper motifs, are essential for nuclear transport of hepatitis delta antigen.

Hepatitis delta antigen (HDAg) is the only known protein of hepatitis delta virus and was previously shown to localize in the nucleoplasm of infected liver cells. In this study, nuclear localization signals of HDAg were defined by expressing various domains of the antigen in both hepatic and nonhepatic cells as beta-galactosidase fusion proteins. A cytochemical staining assay demonstrated that a domain from amino acid residues 35 to 88 of HDAg was able to facilitate transport to the nucleus of the originally cytoplasm-localized protein beta-galactosidase. Two nuclear localization signals, NLS1 and NLS2, which are similar to those of simian virus 40 T antigen and polyomavirus T antigen, respectively, were identified. Either NLS1 or NLS2 alone was sufficient for the nuclear transport of HDAg. However, a fusion protein (N65Z) containing beta-galactosidase and the N-terminal 65 amino acids of HDAg, containing NLS1, was localized exclusively in the cytoplasm and perinuclear region. A possible hydrophobic subdomain between amino acid residues 50 and 65 may block the function of NLS1. Nevertheless, N65Z could enter the nuclei of transfected cells when it was coexpressed with full-length HDAg. Entry into the nucleus may be mediated by the coiled-coil structure rather than the putative leucine zipper motif located between amino acid residues 35 and 65. The existence of two independent nuclear localization signals may ensure the proper functioning of HDAg in the multiplication of delta virus in the nucleus. In addition, two putative casein kinase II sites (SRSE-5 and SREE-126) that may be important in controlling the rate of nuclear transport were found in HDAg.

Amino Acid Sequence↗

PubMed1992

Effects of body position and age on membrane diffusing capacity and pulmonary capillary blood volume.

The effects of body position and age on the membrane diffusing capacity (Dm), pulmonary capillary blood volume (Vc), and the single breath carbon monoxide diffusing capacity (Dco) were evaluated in the erect (sitting) and supine positions in 16 normal young men (under 40 years old, younger group) and in 13 older men (over 40 years old, older group). Dm and Vc were estimated by several measurements of the Dco at increasing alveolar oxygen tension (PAO2). The results showed that Dco, Dm, Vc, and Kco (Dco corrected by alveolar volume) decreased with age in both positions. The differences in Dco, VC, and Kco between the two positions (supine minus the erect position) also decreased with age. The mechanisms of the increases in Dco in the supine position remain to be explained but may be due to a change in pulmonary capillary shape from an elliptical (erect position) to a circular configuration (supine position) since Vc increased more than Dm on assuming the supine position. The findings may be of clinical importance since many physicians have attempted to utilize a reduction in the positional change in Dco as a potential marker of disease.

Adult↗

PubMed1992

[Neurogenic pulmonary edema following a grand mal seizure: a case report].

A case of neurogenic pulmonary edema following a grand mal epileptic seizure is presented. This condition is rather rare and the exact pathophysiology remains unknown, but it is believed that the event may be related to transitional increase of intracranial pressure during seizure attack. Pulmonary edema may be a serious complication of epileptic seizure. Rapid recognition and management is very important since the prognosis depends on the severity of pulmonary edema and appropriate treatment.

Adolescent↗