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Biomedical subjects

S L Chen

Publications and source records attributed to S L Chen.

At least 19 recordsLinked to original sources
PubMed1992

Cloning and expression in Escherichia coli of the gene encoding an extracellular deoxyribonuclease (DNase) from Aeromonas hydrophila.

The gene encoding an extracellular DNase from Aeromonas hydrophila CHC-1 has been cloned and sequenced. Following expression of the dns in Escherichia coli, it was revealed that some of the cloned enzyme was present in the cell-free extracellular supernatant fluid, and there was no cell lysis and concurrent release of cytoplasmic or periplasmic proteins. Therefore, results suggest that E. coli cells were capable of secreting the DNase extracellularly, albeit very inefficiently. The dns is transcribed from its own promoter in E. coli, and expressed as a 25-kDa product, as determined by sodium dodecyl sulfate-polyacrylamide-gel electrophoresis of the culture supernatant preparations followed by a DNA-hydrolysis assay. Nucleotide sequence analysis predicted a single open reading frame of 690 bp encoding a 230-amino acid (aa) polypeptide, with a potential 20-aa signal peptide located at the N terminus of the predicted protein. The deduced aa sequence of the entire protein is highly homologous with that of the DNase of Vibrio cholerae.

Aeromonas hydrophila↗
PubMed1992

Restoring antibody activity of a monoclonal anti-RNP antibody by dissociative HPLC. Demonstration of blocking antibody binding sites with antigen released from effete hybridoma cells.

In biomedical research, monoclonal anti-nuclear antibodies have a number of advantages over polyclonal antibodies in terms of both specificity and reproducibility. However, there are some potential problems in the preparation of monoclonal antibodies. A well characterized mouse monoclonal anti-ribonucleoprotein antibody (anti-RNP antibody, 2.73) known to function in Western blotting was found to lose this activity when produced in vitro from long term hybridoma cell culture. Whilst it could no longer detect RNP antigen by Western blotting, it could still function effectively in affinity purification of RNP antigen. Further studies suggested that this was due to blocking of antibody binding sites by RNP antigen released from effete hybridoma cells in culture. The activity of the antibody in affinity purification was retained because the antigen was stripped away by repeated elutions with 6 M urea. HPLC gel filtration in the presence of 6 M guanidine was able to restore the antibody activity of the protein A purified monoclonal antibody. This finding has important general consequences for the preparation of monoclonal antibodies against antigens present in hybridoma cell culture media.

Animals↗
PubMed1992

Coronary artery abnormalities and right ventricular histology in hypoplastic left heart syndrome.

OBJECTIVES: To determine whether right ventricular preservation is compromised in any anatomic subgroup of hypoplastic left heart syndrome, we assessed the coronary artery anatomy and myocardial histologic features of 151 postmortem specimens with hypoplastic left heart syndrome. BACKGROUND: Although previous studies have shown that coronary artery abnormalities are more prominent in the subgroup of patients who have a patent mitral valve and obstructed aortic valve, it has not been established that these abnormalities compromise right ventricular perfusion. METHODS: Eighty-nine specimens with a patent mitral valve and aortic atresia, 52 with mitral and aortic atresia and 10 with patent mitral and aortic valves were examined. Histologic sections of the right ventricle, left ventricle and coronary arteries were obtained from 64 study hearts and 5 control hearts. RESULTS: Gross coronary anomalies included coronary-cameral communications (n = 29), single left coronary artery (n = 2), single right coronary artery (n = 1) and tortuosity (n = 19). Coronary-cameral communications and tortuosity were significantly associated with the subgroup that had mitral hypoplasia and aortic atresia. Coronary artery wall thickness relative to lumen diameter was not different among the subgroups. No areas of coronary artery stenosis or interruption were discovered. Although endocardial fibroelastosis of the left ventricle was strongly associated with the mitral hypoplasia and aortic atresia group, the right ventricular histologic findings were similar in all subgroups and were not differentially affected by older age. CONCLUSIONS: Although the incidence of coronary abnormalities is greater in patients with mitral hypoplasia and aortic atresia, in this study there was no apparent difference in perfusion of the right ventricle among the anatomic subgroups of hearts with hypoplastic left heart syndrome.

Coronary Vessel Anomalies↗
PubMed1992

[Percutaneous ultrasound-guided thick catheter drainage of retroperitoneal abscess: report of 2 cases].

Retroperitoneal abscess have been a difficult diagnostic and therapeutic challenge in the past. With the advent of precise, noninvasive imaging modalities, they now are defined more easily. Percutaneous guided catheter drainage has changed our traditional therapeutic approach to this disease, in the majority of cases. In general, massive semilytic fatty tissue of retroperitoneal abscess can not pass through the ordinary percutaneous catheter. Herein we report 2 cases of retroperitoneal abscess successfully treated with percutaneous guided thick catheter drainage combined with medical control. Percutaneous guided thick catheter drainage can be performed in most uroradiological facilities. There are many advantages to percutaneous ultrasound-guided thick catheter drainage compared with surgical drainage of retroperitoneal abscess. They include: earlier diagnosis and treatment, avoidance of general anaesthesia, operations which involve risks and complications, shorter and less expensive therapy, easier nursing care, better infection control with the closed drainage system, and greater patient acceptance. Therefore, we believe that a trial of thick catheter percutaneous drainage of retroperitoneal abscess, without a complex septum, should be the initial mode of therapy, and surgical intervention should be undertaken only when percutaneous drainage fails or is contraindicated.

Abscess↗
PubMed1992

[Survey of heavy metals in traditional Chinese medicinal preparations].

Traditional Chinese medicinal preparations are still widely used by natives in Taiwan. Some traditional Chinese medicine prepared with ancient formulas have been found to contain some heavy metals. There has been an occasional pediatric case admitted with heavy metal intoxication. In the last two years, we collected 11 ancient formula drug samples from the families of the patients. We detected the heavy metals with an inductively-coupled plasma atomic emission spectrometry and a graphite furnace atomic absorption spectrometry. The final result of our report reveals the problem of heavy metals in traditional Chinese medicinal preparations as being very serious.

Drugs, Chinese Herbal↗
PubMed1992

[Lupus erythematosus in pregnancy. A prospective study].

The maternal and fetal outcome in 20 patients with lupus erythematosus in pregnancy was studied prospectively. The conditions of the patients were: remission in 4 patients, inactive (controlled by 10 mg prednisone for at least 6 months) 11, active 5 (active disease while pregnancy 3 and first onset and diagnosis during pregnancy 2). There were no maternal death, fetal loss or still birth in full pregnancy course. But the intrauterine malnutrition, low placenta weight and low body weight of newborns were significantly associated with active maternal disease (P < 0.001, P < 0.05). We conclude that (1) family planning pregnancy should be planned in a period while the active disease has been well controlled with a small dose of corticosteroids for at least 6 months. (2) carefully monitoring of the disease activity at intra- and post-partum is essential to lupus patient for a successful birth.

Adult↗
PubMed1992

Detection and analysis of human papillomavirus type 1 infection of skin warts from a dermatology clinic in Taiwan by southern hybridization.

Thirty cases of skin warts from the Dermatology Clinic at Tri-Service General Hospital were analyzed for the presence of human papillomavirus type 1 sequences by Southern blot hybridization. Thirteen of the 30 cases were HPV-1 positive. The prevalence was 43%. Episomal HPV-1 sequences were detected in 11 of 13 HPV-1 positive cases. There are two cases which probably contained integrated forms, one contained the higher molecular weight bands, and the other with 6 kb viral genome may be the result of rearrangement and deletion. Histological studies from HPV-1 positive specimens also indicated the typical features of HPV infection. Some cases with high copy number had a high frequency of inclusion bodies. Chi-square analysis showed that HPV-1 prevalence is not related to sex and different lesion locations, but the prevalence of HPV-1 in recurrent lesions is higher than that of initial lesions.

Adolescent↗
PubMed1992

Influence of age on the synthesis of macromolecules in the smooth muscle cells of the isolated myointimal mass in vitro.

The influence of growth and aging on the synthesis of DNA, RNA and protein in the myointima in vivo was explored by incubating isolated myointima of different ages in labelled precursors. As myointima grew and aged in vivo, the rates of DNA and protein synthesis declined, while the quantity of DNA increased more than two-fold in seven days. The rate of RNA synthesis remained constant and was unaffected by growth. Like that of DNA and protein synthesis, fetal bovine serum was not required by the isolated myointima to synthesize RNA in vitro. Taken together, these findings confirm and extend our previous results which showed the synthetic autonomy of the isolated myointima, and demonstrate further that during growth the synthesis of RNA is affected in a manner that differs from that which controls DNA and protein.

Animals↗
PubMed1991

Base-specific binding of copper(II) to Z-DNA. The 1.3-A single crystal structure of d(m5CGUAm5CG) in the presence of CuCl2.

The single crystal structure of d(m5CGUAm5CG) soaked with copper(II) chloride was solved to atomic (1.3 A) resolution to study the base specificity of copper binding to double-stranded DNA. In the present copper(II) chloride-soaked structure, four crystallographically unique copper(II) complexes were observed bound to five of the six purine bases in the hexamer duplex. Covalent copper(II) binding occurred at N-7 of all four guanine bases and at one of the two adenine bases in the DNA duplex. Copper binding was not observed at the position (Ade4) located in an open solvent channel, whereas the second adenine site (Ade10) shared a complex with a guanine residue (Gua12) of a neighboring symmetry-related hexamer. The coordination geometries and distribution of these copper(II) complexes at the guanine bases in the crystal were comparable to the analogous sites in the isomorphous copper(II) chloride-soaked d(CGCGCG) crystal (Kagawa, T., Geierstanger, B. H., Wang, A. H.-J., and Ho, P.S. (1991) J. Biol. Chem. 266, 20175-20184). Thus, the decreased copper(II) binding affinity for Ade4 was not an artifact of crystal packing, but is intrinsic to the chemical properties of this purine base in duplex DNA. This suggests that the adenine bases in dilute solutions of Z-DNA and more generally other duplex DNA conformations are not susceptible to copper(II) modification. Thus, preferential copper(II) binding at guanine bases over adenine bases in double-stranded DNA may explain the observed specificity of copper(II)-induced oxidative DNA damage near guanine residues (Yamamoto, K., and Kawanishi, S. (1989) J. Biol. Chem. 264, 15435-15440; Sagripanti, J.-L., and Kraemer, K. H. (1989) J. Biol. Chem. 264, 1729-1734). The sharing of a single copper(II) complex by Ade10 and Gua12 of an adjacent hexamer suggests that additional and perhaps specific DNA-DNA interactions, as may be found in the densely packed environment of the nuclear matrix in the cell, may render N-7 of adenine bases prone to copper(II) modification.

Base Sequence↗
PubMed1991

Drug-induced DNA repair: X-ray structure of a DNA-ditercalinium complex.

Ditercalinium is a synthetic anticancer drug that binds to DNA by bis-intercalation and activates DNA repair processes. In prokaryotes, noncovalent DNA-ditercalinium complexes are incorrectly recognized by the uvrABC repair system as covalent lesions on DNA. In eukaryotes, mitochondrial DNA is degraded by excess and futile DNA repair. Using x-ray crystallography, we have determined, to 1.7 A resolution, the three-dimensional structure of a complex of ditercalinium bound to the double-stranded DNA fragment [d(CGCG)]2. The DNA in the complex with ditercalinium is kinked (by 15 degrees) and severely unwound (by 36 degrees) with exceptionally wide major and minor grooves. Recognition of the DNA-ditercalinium complex by uvrABC in prokaryotes, and by mitochondrial DNA repair systems in eukaryotes, might be related to drug-induced distortion of the DNA helix.

Base Sequence↗
PubMed1991

Antibody penetration of viable human cells. I. Increased penetration of human lymphocytes by anti-RNP IgG.

Antibody penetration of viable cells and interaction with intracellular antigens may have major consequences for immunopathological processes in connective tissue diseases. We have reported previously that antibody can penetrate viable human lymphocytes. To assess further the role of antinuclear antibodies in this process, peripheral blood lymphocytes (PBMC) were incubated with FITC-conjugated IgG fractions from sera containing anti-RNP (anti-RNP IgG), Ro(SS-A), La(SS-B) and dsDNA antibodies and control sera for 24 h. Using crystal violet to quench cell surface staining, intracellular fluorescence of viable lymphocytes was quantified on the flow cytometer. It was noted that anti-RNP IgG entered 46.4 +/- 7.2% of lymphocytes which was significantly higher than anti-Ro(SS-A) (29.9 +/- 4.1%, P less than 0.05), La(SS-B) (22.0 +/- 7.5%, P less than 0.01) IgG and control IgG (28.8 +/- 2.1%, P less than 0.05) and not statistically different from anti-dsDNA IgG (32.6 +/- 14.3%). Inhibition experiments showed that the increased number of cells penetrated by anti-RNP IgG was a specific process. Time-course studies showed that anti-RNP IgG entry into cells was different from pooled control IgG. With anti-RNP IgG, positive-staining lymphocytes gradually increased in number from 12 to 24 h incubation, whilst with pooled control IgG, the peak was reached within 5 min. Dual staining experiments suggested that whereas both anti-RNP IgG and pooled control IgG entered B and NK cells, anti-RNP IgG also entered T cells. Using IgG F(ab')2 and Fc fragments from either anti-RNP IgG or pooled control IgG to compete with their FITC-conjugated counterparts indicated that the entry of anti-RNP IgG into-viable cells appeared to involve both F(ab')2 and Fc fragments, and pooled control IgG depended exclusively on the Fc portion of IgG. Further investigation by incubating anti-RNP IgG with 35S-methionine-labelled monocyte-depleted PBMC (MD-PBMC) suggested that anti-RNP IgG might react with the corresponding antigens either on the cell surface or within the cytoplasm.

Animals↗
PubMed1991

[Pelvic lipomatosis associated with cystitis glandularis--case report].

Pelvic lipomatosis is a rare benign disease of unknown etiology characterized by the proliferation of infiltrating fatty tissue within the deep bony pelvis. These fatty tissue may enclose the pelvic and retroperitoneal organs and various degrees of luminal compression and obstruction may happen. There is no typical presenting symptoms of pelvic lipomatosis. The major diagnostic methods are radiological examinations. CT scan is the definitive test to confirm the diagnosis. Open biopsy may be necessary when the diagnosis is inconclusive. Various treatment modalities have been tried, but only the diet therapy and complete ablation of fatty tissue ever reported to be successful. Cystitis glandularis, a rare proliferative inflammatory disease of the bladder, is reported to occur concurrently with pelvic lipomatosis in a patient. Herein we report a similar case. A middle-aged male patient was admitted with the chief complaint of painless gross hematuria for two weeks. After admission a series of radiological examinations and endoscopic bladder biopsy were performed. He was proved to be a rare case of pelvic lipomatosis associated with cystitis glandularis.

Adult↗
PubMed1991

[Diagnostic value of 99mTc-PMT delayed hepatobiliary imaging in small hepatocellular carcinoma--an analysis of 62 cases].

99mTc-PMT delayed hepatobiliary imaging was performed preoperatively in 62 patients with small hepatocellular carcinoma. All patients received operation and had pathological proof. All these tumors were smaller than 5 cm in size. Liver scan was done 5 min, 2 and 5 hr after administration of radiopharmaceutics. The sensitivity was 33.3% (2/6), 41.2% (7/17), 60.0% (9/15) and 54.2% (13/24) in tumors with sizes of less than or equal to 2 cm, 2-3 cm, 3-4 cm and 4-5 cm groups, respectively. The positive rates in the first two groups were lower than in the last two groups but much higher than those by conventional imaging. The total positive rate was 50.0%. The difference was not significant in comparison with the group of tumor size greater than 5 cm. The smallest mass detectable was only 1.2 cm in diameter. The uptake of radiopharmaceutic was not related to serum AFP level and hepatic cirrhosis (P greater than 0.05). These results show that 99mTc-PMT delayed hepatobiliary imaging may be useful in the diagnosis, particularly in the pathognomonic diagnosis, of small hepatocellular carcinoma.

Adult↗
PubMed1991

Prenatal diagnosis of intracardiac rhabdomyoma: a case report.

We report on a case of intracardiac rhabdomyoma diagnosed prenatally from two-dimensional echocardiograms. The tumor was diagnosed by intrauterine echocardiography at the 38th week of gestation. Autopsy proved that the intracardiac tumor was a rhabdomyoma. Tuberous sclerosis spots in the brain tissue were also found.

Adult↗
PubMed1991

[Dynamic investigation of antithrombin III in the plasma of patients with acute myocardial infarction].

Antithrombin III level in the plasma of patients with AMI was determined dynamically by using the methods of chromogenic substrate and rocket electrophoresis. Meanwhile, plasma specimens of 40 normal subjects were examined with the same method. The results showed that the AT III level in AMI patients was much lower than that in normal controls at the first and third day after infarction. The level was also significantly lower than that at the 7th, 14th and 21st day after the onset of the disease. It revealed that there was a hypercoagulative state in patients within the first three days of infarction. The AT III level in patients who died within ten days was much lower than that in the survivor group, P less than 0.01. The authors concluded that a patient may be in a severe condition when their plasma AT III levels decrease apparently and persistently.

Adult↗
PubMed1990

Chlorobutanol, a preservative of desmopressin, inhibits human platelet aggregation and release in vitro.

Therapeutic preparations of desmopressin for parenteral use contain the preservative chlorobutanol (5 mg/ml). We show here that chlorobutanol is a potent inhibitor of platelet aggregation and release. It exhibited a significant inhibitory activity toward several aggregation inducers in a concentration- and time-dependent manner. Thromboxane B2 formation, ATP release, and elevation of cytosolic free calcium caused by collagen, ADP, epinephrine, arachidonic acid and thrombin respectively were markedly inhibited by chlorobutanol. Chlorobutanol had no effect on elastase-treated platelets and its antiplatelet effect could be reversed. It is concluded that the antiplatelet effect of chlorobutanol is mainly due to its inhibition on the arachidonic acid pathway but it is unlikely to have a nonspecific toxic effect. This antiplatelet effect of chlorobutanol suggests that desmopressin, when administered for improving hemostasis, should not contain chlorobutanol as a preservative.

Adenosine Triphosphate↗