Search PubMed⌕ Search

Biomedical subjects

S Chou

Publications and source records attributed to S Chou.

At least 73 records · Page 4Linked to original sources
PubMed1992

Molecular epidemiology of envelope glycoprotein H of human cytomegalovirus.

The complete envelope glycoprotein H (gH) coding sequences of 10 clinical strains of cytomegalovirus (CMV) were determined and compared with those of laboratory strains AD169 and Towne. Their translated peptide sequences segregated into two groups, exemplified by AD169 and Towne. Peptide variation was mostly group-specific and was clustered in the first 37 amino acids, including the signal sequence; in the rest of the molecule, there were scattered amino acid substitutions, usually in single residues. Compared with CMV envelope glycoprotein B, gH is more highly conserved among strains and may be expected to have limited immunologic diversity.

Amino Acid Sequence↗
PubMed1992

Effect of interstrain variation on diagnostic DNA amplification of the cytomegalovirus major immediate-early gene region.

The immediate-early region exon 4 sequences of six clinical cytomegalovirus strains were determined and compared with those of laboratory strains AD169 and Towne. Of 407 codons in exon 4, 33 (8.1%) showed interstrain variation at the peptide level and 74 (18%) showed interstrain variation at the nucleotide level. Variation occurred sporadically throughout the exon, and no grouping of strains was apparent. Published oligonucleotide primers proposed for diagnostic detection of cytomegalovirus by polymerase chain reaction have often been based on exon 4 sequences. Some of these primers show sequence mismatches with strains sequenced here. Amplification sensitivity for mismatched strains was reduced up to 100-fold. More-uniform detection sensitivity was achieved with primers of conserved sequence.

Base Sequence↗
PubMed1992

Right-angle light scattering to assay basal and regulated plasma membrane Cl- conductances.

We describe a simple and rapid technique for assaying both constitutive and regulated plasma membrane Cl- conductances. The method uses right-angle light scattering to measure the rate of swelling of cells in suspension, in which the anion conductance is rate limiting for swelling, due to introduction of high plasma membrane cation conductance using gramicidin. The technique was verified using Chinese hamster ovary cells and mouse L cells, both stably transfected with the cystic fibrosis transmembrane conductance regulator (CFTR), to confer a specific cAMP-activated Cl- conductance not normally present in these cell types. In agreement with results obtained using other methods for assaying Cl- permeability in these cells, forskolin stimulated a significant increase in plasma membrane Cl- conductance in CFTR-expressing cells, as indicated by an increase in light scattering. That the enhanced light scattering by the cells was the result of cell swelling due to NaCl influx was shown by ion substitution experiments, in which no forskolin-induced increase in light scatter occurred in N-methyl-D-glucamine Cl- or Na+ gluconate medium. Enhanced light scattering was also observed in both CFTR-expressing and control cells stimulated with the Ca2+ ionophore, ionomycin. Extracellular anion substitution, to exploit the inwardly directed halide gradient utilized in this protocol, enabled determination of the anion selectivities of both the cAMP- and Ca(2+)-activated Cl- channels. Thus this technique provides a simple optical method for rapidly assaying not only constitutive and regulated Cl- conductance pathways but also their anion selectivities.

Animals↗
PubMed1991

Topoisomerase inhibitors have potent differentiation-inducing activity for human and mouse myeloid leukemia cells.

DNA topoisomerase inhibitors, camptothecin and 4'-demethylepipodophyllotoxin ethylidene-beta-D-glucoside (VP16) had strong differentiation-inducing activity for all five kinds of leukemia cells examined (human HL60, U937, ML1, and K562 cells and mouse M1 cells) as judged from measurements of various differentiation markers. The characteristics that appeared as a result of differentiation induced by these inhibitors were essentially similar in every cell line. Exposure to VP16 for 2 h induced both differentiation and DNA-strand breaks in K562 cells, whereas podophyllotoxin, which lacks topoisomerase II inhibitory activity, induced neither differentiation nor DNA-strand breaks in these cells. These results suggest a parallelism between the induction of differentiation and that of DNA-strand breaks. The combination of VP16 and recombinant tumor necrosis factor alpha (rTNF alpha) synergistically induced differentiation of human U937, ML1, and M1 cells and had an additive effect on HL60 cells. Simultaneous treatment with rTNF alpha plus camptothecin or VP16, or pretreatment with camptothecin or VP16, followed by rTNF alpha induced marked differentiation of M1 cells. These results indicate that inhibition of topoisomerase (either topoisomerase I or II) followed by the action of rTNF alpha was effective in inducing differentiation of leukemia cells.

Animals↗
PubMed1991

Cellular fatty acid composition of Plesiomonas shigelloides.

The cellular fatty acid compositions of 29 strains of Plesiomonas shigelloides and 5 strains of Aeromonas hydrophila were studied. The cellular fatty acid compositions of all the Plesiomonas strains were identical and characterized by the presence of hexadecanoate (16:0) (33%), hexadecenoate (16:1) (28%), octadecenoate (18:1) (9%), and octadecanoate (18:0) (6%). The cellular fatty acid composition of A. hydrophila was similar to that of the Plesiomonas strains, except that the former contained an average of 25% 16:0, 29% 16:1, 12% 18:1, and 2% 18:0 acids compared with 33, 28, 9, and 6%, respectively, for the latter. The percentage ratios of 16:1 to 16:0 and 18:1 to 18:0 could be used to differentiate P. shigelloides from A. hydrophila. These ratios were 0.8 and 1.5 for the former and 1.2 and 6.0 for the latter.

Aeromonas↗
PubMed1991

Gastric volvulus--a late complication of gastrostomy.

Two cases of gastric volvulus are reviewed. Both patients were nonverbal, mentally handicapped children, who were fed through a gastrostomy. They had intermittent intolerance to bolus feeds through the gastrostomy, accompanied by abdominal distension and vomiting of gastric contents. One had a previous partial fundoplication and gastrostomy, and the other had had two pyloroplasties and gastrostomy. The axis of torsion ran from the esophagogastric junction to the gastrostomy site. Both children were treated by detorsion and gastropexy. It is postulated that the gastrostomy served as a fixed point for the volvulus. This was facilitated by the chronically dilated stomachs induced by bolus feeds. These two cases are reported to alert the clinician to this possibility when a neurologically impaired child with a gastrostomy presents with feeding difficulties and persistent vomiting.

Adolescent↗
PubMed1990

Induction of differentiation of human and mouse myeloid leukemia cells by camptothecin.

Low concentrations of camptothecin induced differentiation of human and mouse myeloid leukemia cells including human HL60, U937, ML1, and K562 cells and mouse M1 cells as measured by various differentiation-associated properties. When K562 cells were pretreated with 20 nM camptothecin for 2 h, 53% of the cells were induced to differentiate as measured by NBT staining. Significant single strand breaks in DNA of K562 cells were caused by this treatment. Most single strand breaks were accompanied by protein-DNA cross linking. The combination of camptothecin and rTNF synergistically induced differentiation of human ML1, U937, and M1 cells. These results suggest that topo I may be important in some differentiation of myeloid leukemia cells.

Animals↗
PubMed1990

Induction of differentiation of human leukemia cells by various combinations of cytokines and low-molecular-weight inducers.

To explore agents for differentiation therapy of leukemias, various combinations of cytokines and low-molecular-weight inducers were examined for differentiation-inducing activity toward three kinds of human leukemia-derived cell lines. The strongest differentiation inducing activity on promyelocytic HL60 cells and histiocytic U937 cells was obtained by combining recombinant tumor necrosis factor (rTNF), interferon-gamma (IFN-gamma), retinoic acid (RA), and 1 alpha,25-dihydroxyvitamin D3 (1 alpha,25(OH)2D3). For myeloblastic ML1 cells, the combination of rTNF, IFN-gamma, and RA had the strongest differentiation-inducing activity.

Biological Factors↗
PubMed1990

[Effects of intra-arterial infusion of degradable starch microspheres on liver tissue blood flow].

The effects of intra-arterial infusion of degradable starch microspheres (DSM) on liver tissue blood flow were estimated in rat with liver carcinoma induced by 3'-methyl-4-dimethylaminoazobenzene (3'-Me-DAB) administration. Tissue blood flow of tumor and normal liver was measured simultaneously by Laser blood flowmeter. Tissue blood flow of tumor and normal liver was 13.3 +/- 6.9, 13.2 +/- 4.3 (ml/min/100 g), respectively. After intra-arterial infusion of DSM, tissue blood flow of both tumor and normal liver decreased to the same degree as that at hepatic artery occlusion and then gradually recovered. This gradual recovery of tissue blood flow was supposed to express the process of resolution of DSM by alpha-amylase. The recovery time of tissue blood flow following intra-arterial infusion of DSM was 27.3 +/- 4.0 min (DSM 20 mg/kg) and 70.0 +/- 23.6 min (DSM 30 mg/kg) in tumor and 20.0 +/- 3.3 min and 36.5 +/- 18.0 min, respectively, in normal liver. Thus, the blocking effect of blood flow by DSM was different between tumor and normal liver and proved to be more persistent in the former.

Animals↗
PubMed1989

Fatty acid profiles of Chlamydia using capillary gas chromatography.

Fatty acid profiles of purified elementary bodies of Chlamydia trachomatis (CT) serotypes D, G and L3 were investigated by gas liquid chromatography (GLC) utilizing three fused silica capillary columns of different polarities. CT serotype C and C. psittaci (CP) strain DD34 were investigated using one column only due to the lack of adequate quantities of purified material. Significantly similar fatty acid profiles were observed in the serotypes examined. However, based on the percentage ratio of 13-methyl tetradecanoate (i-15:0) to 12-methyl tetradecanoate (a-15:0), serotypes D and L3, with ratios of 0.18 and 0.19, respectively, could be differentiated from serotypes C and G with ratios of 1.3 and 1.5, respectively. CP demonstrated a ratio of 0.4, thus differentiating it from the CT serotypes examined. Fatty acids i-15:0 and a-15:0 were absent in uninfected McCoy cells. Results were significantly comparable in all three capillary columns. This study suggests that GLC could be used for identification and differentiation of Chlamydia serotypes.

Chlamydia trachomatis↗
PubMed1989

Hereditary sacrococcygeal teratomas.

Hereditary presacral teratoma and its associated anomalies have been described in six kindreds. We report on a similar family where the father presents with a presumed meningocele and his two children with sacrococcygeal teratomas, associated with anterior meningocele in one.

Adult↗
PubMed1989

Definitive treatment of focal nodular hyperplasia of the liver by ethanol embolization.

Focal nodular hyperplasia (FNH) is a benign, usually asymptomatic liver tumor with no predisposition to spontaneous hemorrhage. Treatment is not mandatory unless large size, compression symptoms, or fear of traumatic hemorrhage indicate otherwise. Ethanol embolotherapy offers a safe and effective alternative to surgery. FNH lends itself particularly well to embolotherapy because it is usually fed by a single end-artery with no intratumoral arteriovenous shunting or parasitic blood supply. An illustrative case is presented. Diagnosis was established by ultrasound, computed tomography (CT) scan, radionuclide scan, and arteriography and was confirmed by biopsy. Ethanol embolization resulted in shrinkage of a 10 x 14 cm tumor to a 1.5-cm calcified nodule over an 18-month period.

Adolescent↗
PubMed1989

Atrial natriuretic peptide in patients with obstructive uropathy.

Renal response to release of bilateral ureteral obstruction resembles that to intravenous administration of atrial natriuretic peptide. In a prospective study we measured plasma atrial natriuretic peptide levels before and serially after relief of obstruction in 9 patients (mean age 65 +/- 2 years old) with bilateral ureteral obstruction and azotemia. Obstruction was documented by renal ultrasonography. Before relief of obstruction blood urea nitrogen and serum creatinine levels were 85 +/- 18 (mean +/- standard error) and 8.2 +/- 1.3 mg. per dl., respectively, accompanied by metabolic acidosis but not hyperkalemia. Mean plasma atrial natriuretic peptide (measured by radioimmunoassay) was 129 +/- 28, which was markedly elevated compared to 46 +/- 7 pg. per ml. in 7 age-matched control subjects (p less than 0.01). After relief of obstruction, prominent post-obstructive diuresis and natriuresis ensued; the plasma atrial natriuretic peptide level progressively decreased to that noted in the control group, accompanied by improvement in renal function, and diminishing diuresis and natriuresis. These findings were associated with a significant weight loss and an increase in plasma renin activity (from a mean of 1.57 +/- 0.68 to 5.27 +/- 1.82 ng. per ml. per hour, p less than 0.01). These results suggest that atrial natriuretic peptide release is augmented in patients with bilateral ureteral obstruction and azotemia, probably due to hypervolemia, and may contribute to post-obstructive diuresis and natriuresis.

Atrial Natriuretic Factor↗
PubMed1988

Primary lateral sclerosis. A clinical diagnosis reemerges.

Adults with slowly progressive noninherited gait disorders may show no abnormalities on examination other than signs implicating the corticospinal tracts. That is the syndrome of "primary lateral sclerosis" (PLS), a clinical diagnosis that has been avoided because it is a diagnosis of exclusion, proven only at autopsy. Now, modern technology can exclude other disorders that can cause the syndrome with an accuracy of about 95%. That serves to eliminate the following: compressive lesions at the foramen magnum or cervical spinal cord, multiple sclerosis, amyotrophic lateral sclerosis, Chiari malformation, syringomyelia, biochemical abnormality, and persistent infection with human immunodeficiency virus or human T-lymphotrophic virus type I. We studied three autopsy-proved cases of PLS; six living patients in whom PLS was diagnosed clinically after comprehensive evaluations that excluded the alternative diagnoses; and two patients with this syndrome of PLS and antibodies to human immunodeficiency virus seropositivity that clinically resembled PLS. Primary lateral sclerosis is now a respectable and permissible diagnosis.

Adult↗