Search PubMed⌕ Search

Biomedical subjects

C H Su

Publications and source records attributed to C H Su.

85 records · Page 5Linked to original sources
PubMed1975

Rapid cessation of phospholipid synthesis in fructose-1,6-diphosphate aldolase mutants of Escherichia coli.

Escherichia coli GH352, which was originally described as a temperature-sensitive strain containing a thermolabile acyl coenzyme A:monoacylglycerol 3-phosphate acyltransferase, does not now contain a thermolabile form of this enzyme. It has a defect in fructose-1,6-diphosphate aldolase and at least one additional temperature-sensitive lesion. Both strains GH352 and NP315, a temperature-sensitive aldolase mutant, show rapid cessation of 32-P1 incorporation into nucleic acids and phospholipids at 42 C. These characteristics of strain GH352 are therefore no longer attributed to thermolabile phospholipid synthesis, but can be attributed to the fructose-1,6-diphophate aldolase lesion.

Acyltransferases↗
PubMed1975

Genetic characterization of the metK locus in Escherichia coli K-12.

Three independently isolated metK mutants have been shown to have leisions lying between speB and glc near 57 min on the Escherichia coli chromosome. Two deletions result in a lack of the metC gene product but neither extends into the metK glc region. The three metK mutations are recessive to the wild-type allele carried on the KLF16 episome.

Arginine↗
PubMed1971

Regulation of methionine biosynthesis in Escherichia coli: mapping of the metJ locus and properties of a metJ plus-metJ minus diploid.

MetJ(-) mutants of Escherichia coli have elevated nonrepressible levels of the enzymes of methionine biosynthesis and S-adenosylmethionine synthetase (ATP:L-methionine S-adenosyltransferase, EC 2.5.1.6). In E. coli, as in Salmonella typhimurium, the metJ locus is close to metB (95% cotransduction of metB and metJ markers), but in E. coli the order is reversed, with metJ mapping clockwise to metB. A stable merodiploid, heterozygous for metJ, is subject to repression by methionine. Thus, metJ functions via a diffusible product. MetJ could either be a regulatory locus or could code for an enzyme required for the synthesis of a methionine metabolite that functions in the control system.

Journal Article↗
PubMed1970

Regulation of S-adenosylmethionine synthetase in Escherichia coli.

Addition of methionine to the growth medium of Escherichia coli K-12 leads to a reduction in the specific activity of S-adenosylmethionine (SAM) synthetase. Thus the enzyme appears to be repressible rather than inducible. Mutant strains (probably metJ(-)) are constitutive for SAM synthetase as well as for the methionine biosynthetic enzymes, suggesting that the regulatory systems for these enzymes have at least some elements in common. Cells grown to stationary phase in complete medium, which have low specific activities of the enzymes, were routinely used for derepression experiments. The lag in growth and derepression when these cells are incubated in minimal medium is shortened by threonine. Ethionine, norleucine, and alpha-methylmethionine are poor substrates or nonsubstrates for SAM synthetase and are ineffective repressors. Selenomethionine, a better substrate for SAM synthetase than methionine, is also slightly more effective at repression than methionine. Although SAM is considered to be a likely candidate for the corepressor in the control of the methionine biosynthetic enzymes, addition of SAM to the growth medium does not cause repression. Measurement of SAM uptake shows that too little is taken into the cells to have a significant effect, even if it were active in the control system.

Adenosine Triphosphate↗
PubMedDate not supplied

Factors affecting morbidity and mortality in biliary tract surgery.

Thirty-six clinical and laboratory parameters in 770 consecutive patients undergoing biliary tract surgery over a 3 year period were analyzed in an effort to define the patients at greatest risk. Twelve parameters had a significant correlation with hospital mortality, while multivariate analysis revealed that septic shock, malignant obstruction, serum albumin less than 3.0 gm%, history of hypertension, and plasma urea nitrogen greater than 20 mg% had an independent significance in predicting postoperative mortality. The presence of more than 2 of these risk factors identified a group of patients with an 18% mortality rate. It is for this group of patients that adequate pre-operative preparation such as fluid resuscitation, prophylactic antibiotics, and nutritional support are essential. The controversial preoperative biliary drainage might be only indicated in this group of patients.

Adolescent↗
PubMedDate not supplied

Management of pancreatic lesions in von Hippel-Lindau disease.

Twelve patients with von Hippel-Lindau disease were collected in our institute from 1981 to 1995. All had a family history of the disease. Eleven patients underwent abdominal computed tomography, sonography, or angiographic studies. Ten had pancreatic involvement that included cystic lesions in nine and a solid lesion in one. Seven patients were asymptomatic. Another three presented with obstructive jaundice or upper gastrointestinal (UGI) bleeding. Except for case 8, who died of a central nervous system complication soon after diagnosis of the pancreatic lesion, the other patients had been found to have pancreatic involvement for a variable period of time, ranging from 1 to 13 years (median 5 years). Serous cystadenoma was proved pathologically in two with cystic lesions, and pancreatic endocrine tumor was diagnosed in one with a solid mass. One patient (case 1) underwent biliary bypass due to obstructive jaundice and died of cholangitis and pneumonia 6 years later. One patient (case 3) had total pancreatectomy and lived well with good diabetic control for more than 5 years. The patient with a solid lesion was explored because of repeated UGI bleeding. Surgical resection was impossible owing to advanced tumor with vascular involvement, and a pancreatic endocrine tumor was diagnosed pathologically. He was followed for 1 year. The other seven patients remained asymptomatic during the successive follow-up period. From a literature review and our own experience, we suggest that conservative measures are adequate for the cystic lesions; however, aggressive resection is mandatory for a solid pancreatic lesion in von Hippel-Lindau disease.

Adult↗
PubMedDate not supplied

Factors affecting morbidity, mortality and survival after pancreaticoduodenectomy for carcinoma of the ampulla of Vater.

BACKGROUND/AIMS: The aim of this paper is to reevaluate the factors responsible for hospital morbidity, mortality and post-operative survival following pancreaticoduodenectomy for ampullary cancer. METHODOLOGY: Peri-operative data on 132 patients undergoing pancreaticoduodenectomy for ampullary cancer were correlated with post-operative morbidity, mortality and long-term survival. RESULTS: Three factors were found to correlate well with post-operative morbidity; however, only intraabdominal or wound sepsis was an independently significant variable. Four parameters correlated well with hospital mortality, while multivariate analysis revealed age > 75 y/o, positive blood culture and albumin < or = 3.0 g% to be independently significant in predicting post-operative mortality. Univariate analysis identified seven significant factors: 1) age < or = 75 y/o, 2) hematocrit > 30%, 3) blood urea nitrogen < 20 mg%, 4) earlier TNM staging, 5) smaller tumor size, 6) negative nodal status and 7) well-differentiated tumors, which were associated with longer survival. However, multivariate analysis disclosed nodal status and hematocrit to be the two most significant independent variables. CONCLUSIONS: Although radical resection for ampullary cancer can be performed with a low mortality in recent years, the justification for performing this major operation in a patient over 75 years of age should be reevaluated for prohibitively high mortality (10x) and shorter survival (median 6.0 months). Pre-operative nutritional support and careful surgical technique to prevent post-operative sepsis are mandatory to reduce operative morbidity and mortality. Correction of anemia and adequate lymph node dissection will clarify the patient's survival benefit following this operation.

Adult↗
PubMedDate not supplied

The role of MIB-1 index in the prognosis of resectable pancreatic head cancer.

BACKGROUND/AIMS: Cell kinetics are important indicators of the biological behavior of various human tumors. In this study, we evaluated the prognostic values of the proliferative factors including MIB-1 index, DNA ploidy and S-phase fraction, and further determined the independent prognostic factors in pancreatic head cancer after pancreatoduodenectomy. METHODOLOGY: Patients with pancreatic head cancer undergoing pancreatoduodenectomy were included. Cell proliferative parameters including MIB-1 index, DNA ploidy and S-phase fraction measured by flow cytometry were evaluated and compared with the conventional clinicopathologic factors. RESULTS: There were 21 resectable pancreatic head cancers. By univariate analysis MIB-1 index, cell differentiation and lymphovascular invasion were significant prognostic factors. The 5-year survival rate was 22.2% for overall patients and 29.2% for patients with MIB-1 < or = 11%, while it was 0% for MIB-1 index > 11%, p=0.011. Tumors without lymphovascular invasion had significantly better prognosis than those with lymphovascular invasion (median survival: 38 vs. 10 months, p=0.009). The median survival was significantly longer for well-differentiated cancers than for moderately and poorly differentiated cancers (44 vs. 11 and 9 months, p=0.038). There was no correlation between the MIB-1 index and the other 2 conventional prognostic factors. After multivariate analysis, only the MIB-1 index emerged as the independent prognostic factor. CONCLUSIONS: MIB-1 index played a significant role in the prognosis of the resectable pancreatic head cancer and could potentially complement the conventional factors in predicting the prognosis and determining the optimal treatment strategy. MIB-1 index was also an important independent prognostic factor.

Adult↗
PubMedDate not supplied

Diverticular disease of the small bowel.

BACKGROUND/AIMS: The clinical picture of small bowel diverticula has not been well-clarified because of its infrequent incidence and limited case number in most published reports. We evaluated a large series of small bowel diverticula and further compared the clinical picture of the diverticula at different parts of small bowel. METHODOLOGY: The medical records of 88 patients with diverticular disease of the small bowel were reviewed from 1979-1997. This study included all diverticula from duodenum to ileum. RESULTS: The most common small bowel diverticulum was duodenal diverticulum (45%), followed by Meckel's diverticulum (23%). The most common clinical presentation was abdominal pain (48.9%), followed by gastrointestinal bleeding (29.5%). However, among the Meckel's diverticula, gastrointestinal bleeding (60%) was the most common presentation. The accurate diagnostic rate for diverticula, overall, was 25.0%. Thirty-nine (44.3%) of the diverticula were found incidentally. Twenty-three cases (26.1%) were diagnosed by gastrointestinal barium study. Thirty-eight (42.1%) diverticula were left alone without any sequela, and the remaining 55 (56.8%) diverticula needed either bowel resection (30.7%) or diverticulectomy (26.1%). All of the Meckel's diverticula were treated by surgery. Postoperative complication occurred in 9 (10.3%) patients. Hospital mortality rate was 3.4%. CONCLUSIONS: Duodenal diverticulum was the most common small bowel diverticulum. Abdominal pain and gastrointestinal bleeding were the most common clinical presentations. The small bowel diverticula, except for Meckel's diverticulum, did not need to be treated if there were no significant symptoms.

Abdominal Pain↗
PubMedDate not supplied

Non-functioning islet cell tumors of the pancreas--a multicentric clinical study in Taiwan.

BACKGROUND/AIMS: Islet cell tumors of the pancreas are rare. Functioning tumors are characterized by the symptoms induced by the hormones they secrete. The clinical behaviors of non-functioning tumors are quite different. In this retrospective study, we scrutinized 16 patients with non-functioning islet cell tumor in three tertiary university hospitals in Taiwan during a 20-year period. METHODOLOGY: There were 12 women and 4 men with a mean age of 47 years. Body-weight loss, abdominal pain and palpable mass were the most frequent symptoms. RESULTS: The mean size of these tumors was 8.9 cm in diameter. Ten tumors were located at the tail of pancreas, the other 6 located at the head. Except for hyperbilirubinemia in 2 patients, none of the patients with non-functioning islet cell tumor showed abnormalities of laboratory data including serum tumor markers. Preoperative detection of these tumors by imaging modalities was not difficult due to the large size of the tumors. However, differentiation with functioning tumor or ductal cell carcinoma required clinical and imaging correlation. Fourteen tumors were malignant including 8 with regional lymph nodes involvement, 3 with locally microscopic invasion, 2 with hepatic metastasis and 2 with nearby organ invasion. CONCLUSIONS: Even with its malignant behavior, non-functioning islet cell tumor still possessed a good prognosis after adequate surgical removal in comparison with a higher mortality rate of ductal carcinoma of the pancreas.

Adenoma, Islet Cell↗
PubMedDate not supplied

Retroperitoneal cystic lymphangioma in adults.

Retroperitoneal lymphangioma is an unusual disease, more customarily reported in infants, only occasionally in adults. This paper reports four cases of histologically-confirmed retroperitoneal cystic lymphangiomas detected in adulthood. All four patients presented with palpable abdominal mass. The diagnostic imaging methods used included abdominal ultrasonogram and CT scan. Correct preoperative diagnosis was made in only one case, but four tumors were totally excised. Biochemical analysis of the lymphangioma content from three of the patients proved protein and fat rich. The CT attenuation numbers of both serous and chylous lymphangioma were similar and near that of water and so were not helpful in differential diagnosis with other cystic lesions with watery density content.

Adult↗