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S C Chang

Publications and source records attributed to S C Chang.

At least 19 recordsLinked to original sources
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↗
PubMed1992

Primary malignant melanoma of the vagina and cervix uteri: case report and literature review.

Malignant melanoma of vagina is rare. Malignant melanoma of the cervix is even rare. To date, only 96 cases of the former and 26 cases of the latter have been reported. We report here a very rare case of primary malignant melanoma involving both vagina and cervix in a 70-year-old woman. The clinical, cytologic, light microscopic and ultrastructural findings are presented, and the pertinent literature is reviewed and discussed.

Aged↗
PubMed1992

In vitro antibacterial activities of ticarcillin alone and ticarcillin plus clavulanic acid against beta-lactamase producing and non-producing microorganisms.

A total of 818 clinical bacterial isolates were tested for the production of beta-lactamase by rapid chromogenic cephalosporin method and for the susceptibility to ticarcillin alone and in combination with clavulanic acid (2 micrograms/mL) by agar dilution method. These included 83 strains of methicillin-sensitive Staphylococcus aureus (MSSA), 31 of methicillin-resistant S. aureus (MRSA), 49 of Neisseria gonorrhoeae, 58 of Haemophilus influenzae, 112 of Escherichia coli, 118 of Klebsiella pneumoniae, 58 of Proteus mirabilis, 30 of Proteus vulgaris, 60 of Serratia marcescens, 113 of Enterobacter cloacae, 60 of Pseudomonas aeruginosa and 46 of Bacteroides fragilis. The results revealed that 46.6% of P. mirabilis, 53.4% of H. influenzae, 57.1% of N. gonorrhoeae, 80% of P. vulgaris, 83.9% of MRSA, 85.6% of MSSA, 87.5% of E. coli, 91.7% of S. marcescens, 95.7% of B. fragilis, 98.2% of E. cloacae, and 100% of K. pneumoniae and P. aeruginosa strains produced beta-lactamase. In general, beta-lactamase nonproducers were more susceptible to ticarcillin than beta-lactamase producers. The ranges of minimum inhibitory concentrations (MICs) of ticarcillin for beta-lactamase nonproducers of MSSA, MRSA, H. influenzae, E. coli, P. vulgaris, S. marcescens, E. cloacae, B. fragilis and beta-lactamase producers of MSSA, H. influenzae strains were all within the in vitro susceptible range. The presence of clavulanic acid resulted in a significant enhancement of the antibacterial activity of ticarcillin against beta-lactamase producers of MRSA, N. gonorrhoeae, E. coli, K. pneumoniae, P. mirabilis, P. vulgaris and B. fragilis strains. Clavulanic acid had no synergistic activity for ticarcillin against S. marcescens, P. aeruginosa and E. cloacae.

Bacteria↗
PubMed1992

Urodynamic findings in interstitial cystitis.

Fifty patients with irritative voiding symptoms and a painful bladder when full were engaged in this study to clarify the role of urodynamics in the diagnosis of interstitial cystitis (IC). Patients underwent urodynamic study, cystoscopic hydrodilatation of the bladder under general anesthesia and bladder biopsy. Twenty-eight women and two men who presented with signs of glomerulations or petechial hemorrhage of the bladder mucosa were classified as having IC, while 20 women without this characteristic were classified as having non-IC. A hypersensitive urge sensation, a small bladder capacity, a lower maximal flow rate and an abnormal flow pattern were observed in both groups of patients, but no significant difference was noted. More IC patients had a lower bladder compliance than non-IC patients (p < 0.025), and the maximal bladder capacity under anesthesia was smaller in IC patients (p < 0.05). However, there does not seem to be any definite correlation to the pathologic findings, except in patients with marked bladder inflammation, in whom a small capacity and severe clinical symptomatology were found.

Adult↗
PubMed1992

Epidemiologic investigation of nosocomial outbreak of methicillin-resistant Staphylococcus aureus by plasmid pattern analysis.

Nosocomial infections caused by methicillin-resistant Staphylococcus aureus (MRSA) have become an important problem with increasing frequency. In order to learn if plasmid pattern analysis can be used in epidemiologic investigations of MRSA infections, the authors did plasmid extractions of 70 MRSA stock isolates using a rapid lysostaphin lysis method. All isolates carried at least one plasmid. Most of the isolates had one large plasmid of 24-28 megadaltons (Md). Many also carried one or two small plasmids. Accordingly, 12 different patterns were identified. From these background results, we applied this method to the investigation of two small nosocomial outbreaks of MRSA infection. It was found that the analysis of plasmid pattern and restriction endonuclease analysis are more discriminative than antibiograms. Strains with the same antibiograms can be different by plasmid analysis. It is concluded that the plasmid pattern with a restriction endonuclease analysis study is a reliable method for epidemiologic study of MRSA infections.

Cross Infection↗
PubMed1992

Staging of cervical cancer: comparison between magnetic resonance imaging, computed tomography and pelvic examination under anesthesia.

A prospective study was undertaken to compare magnetic resonance imaging (MRI) with computed tomography (CT) and examination under anesthesia (EUA) in staging cervical carcinoma, with special emphasis on parametrial status. Twenty patients with carcinoma of the cervix, in whom the extent of the disease was surgically confirmed, were analyzed by MRI, CT and EUA. The tumor size estimated by MRI correlated well (r = 0.79, p < 0.001) with those obtained by histopathologic measurement of the surgical specimen. Neither clinical examination nor CT could precisely estimate tumor size. The overall accuracy rate of MRI in staging carcinoma of the cervix was 75%, compared with 32% for CT staging and 55% for clinical staging. The accuracy rate of these modalities for parametrial status was 90% for MRI, 55% for CT and 82.5% for EUA. MRI accurately excluded all 20 patients with pelvic side wall, bladder and rectal involvement. In conclusion, MRI is superior to CT and EUA in assessment of the parametrium (90% vs 55% vs 82.5%, p < 0.005). From MRI, tumor size can be estimated precisely. Although a larger scale study comparing MRI and CT is needed to determine their roles, both should help in the diagnosis and selection of proper treatment for cervical carcinoma. Our preliminary report agrees with previous reports that MRI is promising and indispensable. MRI should be routinely used in conjunction with clinical staging to determine appropriate therapy in patients with cervical carcinoma.

Adult↗
PubMed1992

Successful treatment of cytomegalovirus pneumonitis with ganciclovir and high-dose intravenous immunoglobulin in a bone marrow transplant recipient.

A 35-year-old man with acute lymphoblastic leukemia in second remission received an allogeneic bone marrow transplant from an HLA-compatible sibling donor. Unfortunately, cytomegalovirus (CMV) pneumonitis was histologically documented on Day +72. Combination therapy with ganciclovir (9-[2-hydroxy-1-(hydroxy-methyl) ethoxymethyl] guanine) and high-dose intravenous immunoglobulin (IVIG) was started immediately. The treatment comprised a three-week induction course (ganciclovir, 2.5 mg/kg q8h and IVIG, 500 mg/kg qod) and a seven-week fixed-dose maintenance course (ganciclovir 5 mg/kg thrice a week for 20 doses and IVIG 500 mg/kg twice a week for eight doses). The pneumonia resolved gradually, and he was free from symptoms within two weeks. The only significant side effect was moderately severe myelosuppression which was reversible after discontinuation of ganciclovir. The patient had a relapse of leukemia on Day +186, but there was no recurrence of CMV pneumonitis. This result confirms that such combination therapy is effective in the treatment of CMV pneumonitis in a patient with a bone marrow transplant.

Adult↗
PubMed1992

[Identification and typing of Pseudomonas pickettii during an episode of nosocomial outbreak].

From January to April 1989, Pseudomonas pickettii was isolated from clinical specimens of 24 hospitalized patients at the National Taiwan University Hospital in Taipei. The source of the organism was the 0.9% NaCl solution prepared by the hospital pharmacy. A total of 39 isolates of P. pickettii were collected, including 28 from clinical specimens and 11 from 0.9% saline and distilled water during the outbreak. These microorganisms were studied by using four methods, namely, conventional biochemical method, Vitek Auto-Microbic System (Vitek AMS), gas-liquid chromatographic analysis of cellular fatty acids composition and determination of the minimum inhibitory concentrations of 10 different antimicrobial agents. By conventional biochemical method, 16 isolates were typed as biovar 1 and 23 strains were biovar 3. Strains of both biovars were recovered from clinical specimens and 0.9% saline. Vitek AMS was able to identify P. pickettii correctly, but the result of biotyping was not satisfactory. Analysis of cellular fatty acids could rapidly identify P. pickettii to the species level, but could not distinguish the different biovars. By determination of the MICs, the antibiogram could be classified into 9 patterns. Of 16 isolates of P. pickettii biovar 1, 7 (44%) belonged to pattern I, and 9 (56%) pattern II. Strains of both patterns were found in cultures of clinical specimens and 0.9% saline. Of 23 isolates of P. pickettii biovar 3, 11 (48%) belonged to pattern III, 4 (17%) pattern IV and 8 (35%) pattern V to IX. Pattern III and pattern IV were seen in isolates from clinical specimens and 0.9% saline, while pattern V to IX were only seen in isolates from clinical specimens.(ABSTRACT TRUNCATED AT 250 WORDS)

Cross Infection↗
PubMed1992

Primary lung cancer complicated with pneumothorax.

Eighteen lung cancer patients with a pneumothorax complication were studied. Pneumothorax appears rarely in lung cancer patients, having been found in 18 out of 5567 (0.32%) at our hospital over a period of ten years. Of the 18 patients, eight had adenocarcinoma, seven epidermoid carcinoma and three alveolar cell carcinoma. Unlike those of previous reports, our results showed pneumothorax not to be found exclusively on the same side as the lung cancer. It was contralateral in five cases. Pneumothorax was the initial manifestation of lung cancer in three cases and occurred as a complication in another 15. Of these 15 patients, 11 were described as developing pneumothorax between one and twelve months after completion of radiation therapy for lung cancer. Another two patients developed pneumothorax following cytotoxic chemotherapy. Pneumothorax occurred prior to any treatment for lung cancer in the remaining two patients. The factors contributing to pneumothorax in the lung cancer patients were the rupture of the necrotic neoplastic tissue into the pleural cavity, the rupture of a subpleural bleb or the formation of interstitial air due to partial bronchial obstruction by the tumor, complications arising from radiation therapy and cytotoxic chemotherapy, or any combination of such factors. Pneumothorax was an ominous sign for the lung cancer patients. Most (12/14) died within six months of the onset of pneumothorax.

Aged↗
PubMed1991

Modification of morphine-induced analgesia and toxicity by pertussis toxin.

The present study evaluates the effect of pertussis toxin (PTX) on morphine-induced analgesia and lethality. Mice were injected with 0.2 microgram PTX intracerebroventricularly (i.c.v.) and 0.2 micrograms PTX intrathecally (i.t.) or saline. Mice were tested for morphine-induced analgesia (tail flick) and lethality 16 days later; mice were also examined for pentobarbital-induced mortality. Morphine analgesic potency was decreased by approximately 4-fold in PTX-treated mice compared to controls. Conversely, the lethal potency of morphine was increased by 10-fold in PTX-treated mice compared to controls. PTX treatment did not alter the lethal potency of pentobarbital. Morphine-induced analgesia and lethality were dose-dependently antagonized by naloxone in both PTX and saline-treated groups. The results of this study suggest that morphine analgesia is mediated through PTX-sensitive G proteins. On the other hand, morphine-induced lethality appears to be limited by PTX-sensitive factor(s) since PTX treatment enhanced morphine's lethal potency. The increase in lethal potency of morphine may be due to unmasking of an excitatory opioid receptor mediated effect by PTX.

Analgesia↗
PubMed1991

Dissociation of opioid receptor upregulation and functional supersensitivity.

Alterations in brain opioid binding and opioid pharmacodynamics following chronic (8-day) naltrexone (NTX) treatment were determined in pertussis toxin (PTX)-treated mice. Intrathecal (IT) and intracerebroventricular (ICV) PTX produced a time-dependent, long-lasting inhibition of morphine (SC) analgesia without modifying basal nociception. Inhibition was maximal 16 days following PTX treatment, and was still observed at 40 days. Relative to placebo controls, NTX treatment produced supersensitivity to morphine analgesia in all control mice and in mice pretreated with PTX 1 day before NTX. Supersensitivity was not observed in 7-day PTX-pretreated mice. [3H][D-Ala2-D-Leu5]enkephalin ([3H]DADLE) and [3H][D-Ala2-MePhe4-Gly(ol)5]enkephalin ([3H]DAMGO) binding sites were increased by NTX treatment in saline- and PTX-pretreated groups. KDs were unchanged. These results indicate that PTX does not alter opioid antagonist-induced receptor upregulation. However, PTX treatment can diminish morphine potency in upregulated and control mice. Therefore, opioid analgesia in control and upregulated mice appears to be mediated by receptors linked to a common PTX-sensitive G-protein. Furthermore, in 7-day PTX-pretreated mice, NTX increased binding sites without altering morphine potency, which suggests that new binding sites can appear without being functionally coupled.

Analgesia↗