Biomedical subjects

S S Yang

Publications and source records attributed to S S Yang.

At least 37 records · Page 2Linked to original sources

PubMed2001

Formation and regeneration of protoplasts for protease production in Streptomyces rimosus.

To improve the formation and regeneration frequency of protoplasts for protease production, experiments were performed using a cultivation of Streptomyces rimosus TM-55 (CCRC 940061) in a Tryptic-soy broth (TSB) containing 2% of glycine for 2 days. It was found that the protoplast formation decreased with increased incubation temperature and increased ratio of culture broth to vessel volume. The optimal incubation temperature was 28 degreesC and the ratio of culture broth to vessel volume was 2:5. The hypertonic medium containing 10 mM MgCl2, 25 mM CaCl2 and 500 mM sucrose provided high stability for protoplasts. Supplementation with MgSO4, KCl and NaNO3 improved the regeneration frequency of protoplasts. The smear method had a higher protoplast regeneration frequency than the pour plate method. Protoplasts had protease productivity which was similar to that obtained with fresh mycelia, with each milliliter of culture broth yielding 141 units of protease with 3.5 x 10(8) protoplasts and 148 units of protease with 14.25 mg fresh mycelia respectively in a shaking culture, while the values were 15 and eight units of protease in a static culture.

Agar↗

PubMed2001

[Cloning of gene related to salt tolerance from Sinorhizobium fredii RT19 and its expression in Escherichia coli].

A 4.4 kb DNA fragment related to salt tolerance containing three open reading frames was isolated from the gene library of S. fredii strain RT19. By subcloning and functional analysis, only ORF2 related to salt tolerance was obtained. The ORF2 was ligated to expression vectors pThioHisA, B and C, respectively, and recombinant expression vectors pGA, pGB and pGC containing 1.5 kb DNA fragment related to salt tolerance were constructed. These recombinant expression vectors were transformed into E. coli DH5 alpha. Inducing by IPTG and analyzing with SDS-PAGE, it was found that the fusion protein encoded by pGC was expressed, and its molecular weight was equal to the sum of thioredoxin encoded by trxA and ORF2 putative protein molecular weight. The Western blot demonstrated that the target gene was successfully expressed in E. coli.

Cloning, Molecular↗

PubMed2001

Reoperative Snodgrass procedure.

PURPOSE: We examine the results of a reoperative Snodgrass procedure for complex hypospadias. MATERIALS AND METHODS: A total of 25 patients with hypospadias in whom repair had failed underwent a reoperative Snodgrass procedure. Mean patient age and number of prior repairs were 11.4 years and 2.5, respectively. Before this treatment the meatus was at the distal shaft in 10 cases, mid shaft in 9, proximal shaft in 4 and penoscrotal junction in 2. Preoperatively the associated complications were fistulas in 13 patients, residual chordee in 12 and diverticulum in 1. In 8 cases the fistula was incorporated into the hypospadiac opening and treated as a longer defect. The urethral plates were, subjectively, surgically altered or unaltered in 7 and 18 patients, respectively. In 8 patients (group A) the previous repair(s) did not involve dissection of the urethral plate (unaltered) nor was there a fistula. The remaining 17 patients were classified as group B. The neourethra was then reconstructed as the Snodgrass technique. Followup urethral calibration was performed in 17 patients. RESULTS: Mean followup period was 13.7 months. Mean length and size of neourethra were 19.9 mm. and 14Fr, respectively. There were 7 (28%) postoperative fistulas of the neourethra. The incidences of postoperative fistula of the neourethra were 0% and 41.2% in groups A and B, respectively (p <0.01). Statistically the surgically altered urethral plate and the presence of a preoperative fistula were 2 independent factors predicting a higher postoperative fistula rate. The overall postoperative meatal stenosis rate was 13 (52%) with 3 (37.5%) in group A and 10 (58.8%) in group B, respectively (p >0.05). The meatal stenosis was treated with simple dilation in 11 cases and meatoplasty during subsequent fistula repair in 2. Stricture at the anastomostic site between the normal urethra and neourethra was noted in 2 patients. Fistula repair was successfully performed 6 months later in 4 patients. CONCLUSIONS: The Snodgrass procedure is a viable option for the treatment of previously failed hypospadias repair. It was highly effective in patients with a surgically unaltered urethral plate and no preoperative fistula.

Adolescent↗

PubMed2001

Carbon dioxide flux density in cultivated rice paddy field.

The carbon dioxide flux density in a subtropical cultivated rice paddy field were determined over four crop seasons (two consecutive years) at five stages of rice plant development, transplanting, active tillering, booting, flowering and ripening, and an idle period between crops. During 24 h sampling periods at those stages, the CO2 flux densities were measured and found to be -2,000 to 55,000 mg CO2/m2/day in the first year and 600 to 29,000 mg CO2/m2/day in the second year in acrylic chambers covering rice plants. The CO2 flux densities in glass domes without plants but with soil were -700 to 6,000 mg CO2/m2/day in the first year and 147 to 4,500 mg CO2/m2/day in the second year. The data for the CO2 flux density over an entire year are extrapolated. Although our non-controlled environment experiments have inherent drawbacks, the collected data indicate that continuous rice cultivation has a tendency to result in increased CO2 emissions.

Carbon Dioxide↗

PubMed2001

Endoscopic ultrasonography to study the causes of extragastric compression mimicking gastric submucosal tumor.

BACKGROUND AND PURPOSE: Many reports have confirmed that endoscopic ultrasonography (EUS) can differentiate gastric submucosal tumor from extragastric compression, but only a few specifically concentrated on EUS in identifying the causes of external compression. MATERIALS AND METHODS: From May 1993 to May 2001, we used EUS in 238 patients to diagnose gastric submucosal tumor or external compression. We excluded 183 patients who had submucosal tumors and analyzed the remaining 55 patients with extragastric compression. Malignant causes of external compression were proved by surgery or biopsy. Benign causes of external compression were proved by other imaging examinations (abdominal ultrasound, computerized tomography, angiography) or surgery. Patients with external compression caused by normal organs were followed up with repeated upper gastrointestinal endoscopy or EUS. RESULTS: The stomach was compressed by normal extragastric organs in 32 patients (spleen 10, splenic vessel 6, gall bladder 9, liver 3, pancreas 3, and intestine 1), by benign pathologic lesions in 12 patients (liver cyst 7, liver hemagioma 2, splenic cyst 1, pancreatic cyst 1, pancreatic cystadenoma 1) and by malignant tumors in 5 patients (hepatoma 1, liver metastasis from colon cancer 2, pancreatic cystadenocarcinoma 1 and lymphoma of spleen 1). In the remaining six patients, neither submucosal tumor nor external compression was found during EUS examination and the external compression was considered transient. CONCLUSION: When an extragastric compression mimicking submucosal tumor is detected by upper gastrointestinal endoscopy, EUS is indicated to identify the cause of extragastric compression.

Adolescent↗

PubMed2001

Oxytetracycline production by immobilized Streptomyces rimosus.

This study examined whether the production of oxytetracycline by Streptomyces rimosus TM-55 (CCRC 960061) would be improved with calcium alginate immobilization in submerged fermentation compared with free cells. Results showed that in 1-mL culture broth, free cells produced 121 to 124 microg of oxytetracycline, whereas immobilized cells produced 153 to 252 microg. Immobilization of the cells retarded the growth rate of S. rimosus but increased the length of the growth period and improved the oxytetracycline production. The specific oxytetracycline productivity was 33.3 to 34.2 mg in each gram of free dry cells and was 40.2 to 40.7 mg in immobilized dry cells. The optimum immobilization conditions were alginate 2% and bead diameter of 2.13 mm. Oxytetracycline production increased with increasing inoculum density but decreased with increasing bead diameter. Ethylenediaminetetraacetic acid or monovalent ions could react with calcium in the bead or replace it with sodium ion, thereby reducing the strength of the beads.

Alginates↗

PubMed2001

Expression of apoptosis-regulating proteins p53, Bcl-2, and Bax in primary resected esophageal squamous cell carcinoma.

Apoptosis plays a key role in the pathogenesis, aggressiveness, and therapy responsiveness of cancer. Proteins of the Bcl-2 family as well as p53 are important regulators of apoptosis. The present study retrospectively examines the expression of apoptosis-regulating proteins in primary resected esophageal squamous cell carcinoma (ESCC) and the correlation between the outcome of patients' treatment and the expression of the proteins. We used antibodies specific for the human p53, Bcl-2 and Bax proteins to examine the expression of these apoptosis-regulating proteins in 40 archival specimens of patients with primary resected esophageal squamous cell carcinoma. The overall expression of p53, Bcl-2, and Bax was 73%, 18%, and 100%, respectively. No significant correlations were found between the expression of p53, Bcl-2, and Bax. The expression of Bcl-2 had a negative influence on survival in this population of primary resected ESCC patients (p=0.03). But no differences in survival were observed in relation to the expression of p53 or Bax. In conclusion, Bcl-2 expression may provide additional and prognostic information for the clinical course of the disease and therefore to be developed as a prognostic indicator for primary resected esophageal squamous cell carcinoma.

Apoptosis↗

PubMed2000

A second photochromic bacteriophytochrome from Synechocystis sp. PCC 6803: spectral analysis and down-regulation by light.

It now appears that photosynthetic prokaryotes and lower eukaryotes possess higher plant phytochrome-like proteins. In this work, a second phytochrome-like gene was isolated, in addition to the recently identified Cph1 phytochrome, from the Synechocystis sp. PCC 6803, and its gene product was characterized photochemically. The open reading frame sll0821 (designated cph2 in this work) has structural characteristics similar to those of the plant phytochromes and the Synechocystis Cph1 with high amino acid sequence homology in the N-terminal chromophore binding domain. The predicted Cph2 protein consists of 1276 amino acids with a calculated molecular mass of 145 kDa. Interestingly, the Cph2 protein has two putative chromophore binding domains, one around Cys-129 and the other around Cys-1022. The Cph2 was overexpressed in E. coli as an Intein/CBD (chitin binding domain) fusion and in vitro reconstituted with phycocyanobilin (PCB) or phytochromobilin (PPhiB). Both the Cph2-PCB and Cph2-PPhiB adducts showed the typical photochromic reversibility with the difference spectral maxima at 643/690 and 655/701 nm, respectively. The Cys-129 was confirmed to be the chromophore binding residue by in vitro mutagenesis and Zn(2+) fluorescence. The microenvironment of the chromophore in Cph2 seems to be similar to that in plant phytochromes. The cph2 gene expression was dark-induced and down-regulated to a basal level by light, like the cph1 gene. These observations suggest that Synechocystis species have multiple photosensory proteins, probably with distinct roles, as in higher plants.

Amino Acid Sequence↗

PubMed2000

Chromophore-apoprotein interactions in Synechocystis sp. PCC6803 phytochrome Cph1.

The secondary, tertiary, and quaternary structures of the Synechocystis Cph1 phytochrome were investigated by absorption and circular dichroism spectroscopy, size exclusion chromatography, and limited proteolysis. The Cph1 protein was coexpressed with a bacterial thioredoxin in Escherichia coli, reconstituted in vitro with tetrapyrrole chromophores, and purified by chitin affinity chromatography. The resultant Cph1 holoproteins were essentially pure and had the specific absorbance ratio (SAR) of 0.8-0.9. Circular dichroism spectroscopy and limited proteolysis showed that the chromophore binding induced marked conformational changes in the Cph1 protein. The alpha-helical content increased to 42-44% in the holoproteins from 37% in the apoprotein. However, no significant difference in the secondary structure was detected between the Pr and Pfr forms. The tertiary structure of the Cph1 apoprotein appeared to be relatively flexible but became more compact and resistant to tryptic digestion upon chromophore binding. Interestingly, a small chromopeptide of about 30 kDa was still predominant even after longer tryptic digestion. The N-terminal location of this chromopeptide was confirmed by expression in E. coli and in vitro reconstitution with chromophores of the 32.5 kDa N-terminal fragment of the Cph1 protein. This chromopeptide was fully photoreversible with the spectral characteristic similar to that of the full-size Cph1 protein. The Cph1 protein forms dimers through the C-terminal region. These results suggest that the prokaryotic Cph1 phytochrome shares the structural and conformational characteristics of plant phytochromes, such as the two-domain structure consisting of the relatively compact N-terminal and the relatively flexible C-terminal regions, in addition to the chromophore-induced conformational changes.

Apoproteins↗

PubMed2000

Tubularized incised plate urethroplasty for proximal hypospadias.

OBJECTIVE: To review our experience of using the tubularized incised plate (TIP) urethroplasty (useful in the treatment of distal hypospadias) to treat proximal hypospadias. MATERIALS AND METHODS: From March 1997 to March 2000 primary repairs were carried out on 40 boys (mean age 4.5 years) with proximal hypospadias. After degloving the penile skin the meatus was at the mid-shaft in 10 boys, at the proximal penile shaft in 11, at the penoscrotal junction in 16, at the scrotum in two and at the perineum in one. The 21 patients with a mid or proximal shaft meatus were categorized as having mid-shaft and the other 19 as having posterior hypospadias. Tunica albuginea plication (TAP) was used to correct residual ventral curvature. The method of urethroplasty was adapted from that described by Snodgrass. The key step of the TIP repair is a midline incision of the urethral plate; a subcutaneous tissue flap dissected from the inner prepuce is used to cover the neourethra. An 8 or 10 F nasogastric tube is used as a urethral stent and removed 7 or 8 days after surgery. Follow-up endoscopy and urethral sounding were carried out in 17 of the patients aged < 6 years; the mean follow-up was 12.5 months. RESULTS: TAP was used to correct penile curvature in nine (23%) of the patients. Excluding stenosis, the TIP repair was successful in 20 (90%) of those with mid-shaft and in 16 of the 19 with posterior hypospadias; for all complications the respective rates were 19 of 22 and 15 of 19. The overall success rate was 88% for all 40 patients with proximal hypospadias; a urethrocutaneous fistula occurred in two of those with mid-shaft and three of those with posterior hypospadias. Urethral meatal stenosis occurred in four (12%) of the patients (two in each group); two were associated with a fistula and the other two had only mild meatal stenosis. The overall complication rate was 17.5% (three and four in the mid and the posterior hypospadias groups, respectively). The meatal stenosis was managed by simple dilatation in three and meatoplasty in one patient. Endoscopically, the mucosa of neourethra was pink and smooth in all 17 patients assessed. The calibre of all 17 neourethra was > or = 8 F and in 13 was > or = 10 F. CONCLUSION: TIP repair is a reliable method for treating both mid-shaft and posterior hypospadias.

Child, Preschool↗

PubMed2000

Endoscopic treatment of bleeding gastric varices by N-butyl-2-cyanoacrylate (Histoacryl) injection: long-term efficacy and safety.

BACKGROUND: The long-term efficacy and safety of the endoscopic injection of N-butyl-2-cyanoacrylate (Histoacryl) were evaluated to define its role as the initial treatment for bleeding gastric varices. METHODS: Ninety patients with bleeding gastric varices underwent endoscopic injections of Histoacryl for hemostasis within a 6-year period. Histoacryl was injected intravariceally as a 1:1 mixture with Lipiodol. Among the 90 patients, 5 had active bleeding and 85 had recent bleeding. Most of the varices were large (F2 or F3, 85 cases). The most common locations were the fundus and the posterior wall of the proximal body (94.4%). After Histoacryl injection, patients were followed endoscopically with retreatment as necessary. RESULTS: The rate of hemostasis at 1 week was 94.4%. Recurrent bleeding occurred in 23.3% of the patients from 3 days to 16 months after the initial injection. Recurrent bleeding was stopped with reinjections of Histoacryl in 16.7% of the patients. The rate of definitive hemostasis was 93.3% (84 of 90). The treatment failure-related mortality rate was 2.2% (2 of 90). To date, 35 patients have died, mostly as a result of malignancy or liver failure, and 55 are still alive. The determining factor for long-term survival was the underlying disease leading to portal hypertension. There were few long-term complications except for Histoacryl cast extrusion-related mucosal defects. CONCLUSIONS: Endoscopic injection of Histoacryl is highly effective for the treatment of bleeding gastric varices, with rare complications both acutely and long term. This treatment modality is appropriate as the first choice for bleeding gastric varices.

Adult↗

PubMed2000

Variations of the bilirubin uridine-diphosphoglucuronosyl transferase 1A1 gene in healthy Taiwanese.

The activity of uridine-diphosphoglucuronosyl transferase 1 (UGT1) may influence the concentration of serum bilirubin. Because UGT1 is too labile to be measured with classical biochemical methods, we analysed the whole UGT1A1 gene in 290 healthy Taiwanese adults by using the polymerase chain reaction method, and investigated the relationship between UGT1A1 genotypes and serum bilirubin levels. The results showed that slightly more than 50% of the subjects had one or more variant sites in UGT1A1 gene. The most common variant was A(TA)6TAA/A(TA)7TAA (6/7) in the promoter area, followed by heterozygous variation within the coding region, compound heterozygous and homozygous variations. Among the four variant sites within the coding region, 211 G to A was the predominate one, 1091 C to T was a novel variation, and 686 C to A was associated with 6/7. Subjects with 6/7 or heterozygous variation within the coding region or compound heterozygous (plus one homozygous) variation had significantly higher bilirubin levels than those with wild UGT1A1 gene. When the 290 subjects were stratified into six groups according to their serum bilirubin concentrations, the bilirubin levels were correlated well to the frequencies of variant UGT1A1 gene. Our results show that there is a strong association between UGT1A1 gene and bilirubin levels in healthy Taiwanese adults. The occurrence of A(TA)7TAA allele was relatively rare and the variation rate within the coding region was much higher in Taiwanese compared to that in Caucasians.

Adult↗

PubMed2000

Crystallization and preliminary X-ray crystallographic studies of response regulator for cyanobacterial phytochrome, Rcp1.

The key response-regulator gene of light regulation, rcp1, from Synechocystis sp. has been overexpressed, purified and subsequently crystallized using ammonium sulfate as a precipitant in forms suitable for X-ray crystallographic studies. A native data set was collected to a resolution of 2.5 A at cryogenic temperature. The crystals belong to the hexagonal space group P6(3), with unit-cell parameters a = b = 89.04 (5), c = 60.29 (3) A. The Matthews parameter suggests that Rcp1 crystallizes with two molecules per asymmetric unit.

Amino Acid Sequence↗

PubMed2000

Difference in the distribution pattern of Helicobacter pylori and grade of gastritis in the antrum and in the body between duodenal ulcer and benign gastric ulcer patients.

OBJECTIVES: To investigate the relationship between the Helicobacter pylori (H. pylori) colonization and the grade of gastritis in the antrum and in the body of patients with duodenal ulcer (DU) or benign gastric ulcer (BGU). METHODS: This study was performed in H. pylori-positive 220 DU patients and 180 BGU patients. H. pylori density was evaluated by modified Giemsa staining and CLO test, and gastritis grade was graded by H&E staining in the antrum and in the body. RESULTS: H. pylori grade by Giemsa staining was 1.24 in the antrum and 0.82 in the body for DU group (p < 0.01), and those of BGU group were slightly reversed, 0.83 and 0.87, respectively, but without statistical significance. Similarly H. pylori grade by CLO test was 3.1 in the antrum and 2.8 in the body for DU group (p < 0.01), and those of BGU group 2.3 and 2.6 (p < 0.05), respectively. In contrast, gastritis grade was 1.7 in the antrum and 1.2 in the body for DU group (p < 0.01), and those of BGU group 1.6 and 1.3 (p < 0.01), respectively, similar to those of DU. However, there was a correlation between H. pylori grade and gastritis grade in the antrum and in the body, not only in DU but also in BGU group (p < 0.01). CONCLUSION: In spite of different distribution patterns of H. pylori between DU group and BGU group, gastritis grade of the antrum was significantly higher than that of the body in both DU and BGU. However, gastritis is correlated with H. pylori density not only in DU but also in BGU patients. It looks like the inflammatory reaction to H. pylori is stronger in the antrum than in the body.

Adult↗

PubMed2000

Preservation of the thin distal urethra in hypospadias repair.

PURPOSE: We report our experience with preserving the thin distal urethra lacking corpus spongiosum for the treatment of hypospadias. MATERIALS AND METHODS: From January 1997 to October 1999 we treated primary hypospadias in 77 boys with a mean age of 4 years 10 months. After degloving the penile skin a segment of thin distal urethra lacking corpus spongiosum was noted in 18 patients (23.4%) with a mean age of 3 years 5 months. The thin distal urethra was preserved and incorporated as part of urethroplasty (group 1). The procedure was primarily completed by tubularized incised plate urethroplasty. We also performed tubularized incised plate urethroplasty in 31 boys (40.3%) with a mean age of 5 years 2 months who had normal coverage of the corpus spongiosum of a hypospadiac urethra (group 2). We compared the results of treatment in these 2 groups. The remaining 28 patients (36.4%) treated with other methods were excluded from study. RESULTS: In group 1 the distance from the original meatus to the urethra covered by healthy corpus spongiosum was 4 to 20 mm. (mean 8.2). If the thin distal urethra had been excised, the urethral meatus would have been relocated more proximal in these boys. Mean followup in groups 1 and 2 was 9.9 and 7.6 months, respectively. Postoperatively there were 2 (11.1%) urethrocutaneous fistulas in group 1 and 4 (12.9%) in group 2. Tubularized incised plate repair was successful in all 10 cases (100%) of distal hypospadias in group 2, and in 15 of 18 (83.3%) and 17 of 21 (81%) of proximal hypospadias cases in groups 1 and 2, respectively. There was no statistically significant difference in the success rate of hypospadias repair in the groups. CONCLUSIONS: We noted a significantly thin distal urethra in 23.4% of our cases of primary hypospadias. Mean length of the thin distal urethra was 8.2 mm. Preserving the thin distal urethra may simplify the operative procedure without compromising the surgical results of tubularized incised plate urethroplasty.

Adolescent↗

PubMed2000

Surgical management of substernal goiter.

PURPOSE: We describe the clinical results and complications associated with different surgical approaches to the treatment of substernal goiter. METHODS: We retrospectively reviewed the medical records of 56 patients treated for substernal goiter from 1983 through 1999. Eight had undergone previous thyroidectomy. Posterior mediastinal goiter was diagnosed in eight patients, hyperthyroidism in seven, acute respiratory failure in three, and superior vena cava syndrome in two. All but one of the patients underwent thyroidectomy. RESULTS: Thyroid scan revealed that 88% of patients had substernal goiter. A cervical incision alone was used in 46 of 55 patients. Nine patients underwent thyroidectomy via a thoracic approach. Both lobes were resected in 16 patients. Two deaths occurred: one patient suffered a stroke and another patient developed pneumonia after surgery. The most frequent complication was recurrent laryngeal nerve injury, followed by removal of a normal parathyroid gland and pneumonia. Multinodular goiter occurred in 52 patients. Resected goiter with occult malignancy was found in three patients, two of whom underwent lobectomy only. These three patients had survived at 5, 7, and 11 years postoperatively, respectively. All patients with tracheal lumen narrowing showed a normal sized tracheal lumen 2 to 3 months postoperatively. CONCLUSION: Our data indicate that the presence of a substernal goiter should be considered an indication for resection based on risk of acute respiratory distress, risk of malignancy, and lower surgical morbidity. Most secondary substernal goiters can be simply resected through cervical incision and curation.

Adult↗

PubMed2000

[Subcloning and sequencing of DNA fragment related to salt tolerance in Sinorhizobium fredii RT19].

A 23 kb DNA fragment related to salt tolerance was obtained from the gene library of S. fredii strain RT19. In this study, BamH I was selected to digest 23 kb DNA fragment into different length of DNA fragments. The resulting fragments were ligated with plasmid pML122, then the recombinant plasmids were transformed to competent cells of E. coli S17-1 on selective medium and three transformants TR were obtained. Two-parental mating experiments were carried out with these transformants as donor and salt sensitive S. fredii strain RC3-3 as recipient, and the transconjugant BR2 was selected on FY plates containing gentamycin and 0.4 mol/L NaCl. Thus, a 4.4 kb DNA fragment related to salt tolerance was obtained. Based on its physical map, six restriction fragments were subcloned into plasmid pUC18 for DNA sequencing. Subsequently, sequencing and analysis of 4.4 kb DNA fragment showed that fixO, fixN genes and three ORFs were obtained.

Amino Acid Sequence↗

PubMed1999

Outpatient thoracoscopic limited sympathectomy for hyperhidrosis palmaris.

Thoracoscopic sympathectomy is considered the most effective treatment for hyperhidrosis palmaris. We have treated 1,043 cases of this disease by this method. We have developed an outpatient technique of thoracoscopic sympathectomy using electrocautery. This procedure has been used in 47 patients with hyperhidrosis palmaris. The early results have been favorable. We describe this fast, safe, economic, and effective method for the treatment of hyperhidrosis palmaris.

Adolescent↗