Biomedical subjects

Fang-Ming Chen

Publications and source records attributed to Fang-Ming Chen.

12 recordsLinked to original sources

PubMed2004

Molecular detection of APC, K- ras, and p53 mutations in the serum of colorectal cancer patients as circulating biomarkers.

Early detection of tumor DNA in serum/plasma prior to the development of recurrence or metastases could help improve the outcome of patients with colorectal cancer (CRC) after tumor resection. Recent advances in the detection of tumor DNA in the serum/plasma has opened up numerous new areas for investigation and new possibilities for molecular diagnosis. APC and K- ras mutations are considered to be early-stage developments of CRCs, whereas p53 mutations are thought to be relatively late events in the tumorigenesis of CRCs. The aim of this study was to search for the presence of genetic mutations in the DNA extracted from the serum of CRC patients and healthy subjects. We simultaneously evaluate the significance of APC, K- ras, and p53 gene mutations in cancer tissues and their paired serum samples of 104 CRC patients by polymerase chain reaction-single strand conformation polymorphism analysis (PCR-SSCP) followed by direct sequencing. Additionally, analysis was carried out to detect the serum carcinoembryonic antigen (CEA) levels in CRC patients. Overall, we found at least one of the gene mutations in tumor tissues from 75% (78/104) of the CRC patients. Comparison of the three molecular markers showed that the detection rates in the serum were 30.4%, 34.0%, and 34.2% for APC, K- ras, and p53 genes, respectively. Of these patients, 46.2% (36/78) were identified as having positive serum results, whereas all healthy controls remained negative. The overall positive tumor DNA detection rates in the serum were 0% (0/7) for Dukes' A classification, 22.4% (11/49) for Dukes' B, 48.7% (19/39) for Dukes' C, and 66.7% (6/9) for Dukes' D. The detection rate increased as the tumor stage progressed ( p = 0.012). Concurrently, a significant difference was observed between lymph node metastases and positive serum tumor DNA detection ( p < 0.001). A significantly higher postoperative metastasis/recurrence rate in patients harboring gene mutations with serum tumor DNA than those without serum tumor DNA was also demonstrated ( p < 0.001). However, no significant correlation between the postoperative metastasis/recurrence and serum CEA levels was observed ( p = 0.247). These data suggest that the identification of circulating tumor DNA using the molecular detection of APC, K- ras, and p53 gene mutations is a potential tool for early detection of postoperative recurrence/metastases. Moreover, these genes may be potential molecular markers of poor clinical outcome in CRC patients.

Aged↗

PubMed2004

High frequency of G/C transversion on p53 gene alterations in breast cancers from Taiwan.

p53 gene mutation is a very frequent event in many human cancers and is associated with a poor clinical outcome in breast cancer patients. Analysis of p53 gene mutations can also provide clues to the etiology of tumor formation. The present study was conducted to investigate the p53 mutations in patients with breast cancer from Taiwan. Tumor samples from 119 patients undergoing mastectomy for breast cancer were evaluated. The mutational status of the p53 gene (exons 5-8) was screened by polymerase chain reaction-single strand conformation polymorphism analysis followed by direct sequencing. Of all 119 cases of breast carcinoma, 26 mutations of the p53 gene were found in 22 cases (18.5%). Among these mutations, 78% (20/26) were point mutations with the majority of those being missense mutations (75%, 15 of 20 mutations) and the other 22% (6/26) were frameshift mutations. No significant correlation between p53 mutations and clinicopathological features was found, including HER2 status. Moreover, our results disclosed distinct mutation spectra in excess transversions to transitions (15/21, 71.4% vs. 6/21, 28.6%) with GC to CG dominant (6/15, 40%). Mutation hot spots we identified at codons 167, 185, 186, 210, 265 and 295 have rarely been documented in the literature. These findings showed that p53 gene mutation might contribute to the pathogenesis of breast carcinoma. Furthermore, the different mutation spectrum with high transversions in G:C to C:G may imply that the exogenous mutagens outweigh the endogenous processes in breast cancer in patients in Taiwan.

Breast Neoplasms↗

PubMed2004

Alterations of APC, c-met, and p53 genes in tumor tissue and serum of patients with gastric cancers.

BACKGROUND: Gastric cancer is one of the most significant causes of cancer-related death worldwide. A genetic model consisting of sequential accumulations of alterations in specific genes for gastric cancer has been proposed. MATERIALS AND METHODS: The significance of adenomatous polyposis coli (APC) and p53 gene mutations in cancer tissues and their paired serum of 34 gastric cancer patients was investigated using polymerase chain reaction single-strand conformation polymorphism analysis (PCR-SSCP), followed by direct sequencing. c-met mRNA expression was evaluated by reverse-transcription PCR (RT-PCR). Additionally, analyses were carried out to detect the serum carcinoembryonic antigen (CEA) levels, and their correlation to these three molecular markers. Finally, serum molecular markers and their correlation to the presence of postoperative recurrence/metastasis were analyzed. RESULTS: Of all, 32.4% of patients presented mutations in APC and p53, respectively, and 58.8% presented the overexpression in c-met, overall, at least one of these genetic alterations in 79.4% of tumor tissues. Comparison of three molecular markers showed that the individual detection rate in the serum of patients with tumors harboring the same abnormalities was 18.2, 70.0, and 36.4% for APC, c-met, and p53 genes, respectively. In general, 59.3% of serum from cancerous tissues with gene alterations was demonstrated as positive, whereas all healthy volunteers' sera remained negative. Regarding gene alterations in tumor tissues, c-met overexpression was significantly related to the tumor size (P = 0.017), depth of tumor invasion (P = 0.007), lymph-node metastasis (P < 0.001), and TNM stage (P = 0.001). In the serum, c-met overexpression was closely associated with lymph-node metastasis (P = 0.008) and TNM stage (P = 0.016). The overall positive tumor gene detection rate in the serum was prominently correlated to the serum CEA levels (P = 0.038). In addition, a significantly higher postoperative metastasis/recurrence rate in patients harboring gene mutations with serum molecular markers than those without serum molecular markers was also demonstrated (P = 0.014). CONCLUSIONS: Our findings suggest that serum molecular markers can be detected in a substantial proportion of gastric cancer patients, and these may offer an auxiliary approach in the noninvasive detection and prognosis of gastric cancer.

Carcinoembryonic Antigen↗

PubMed2003

Effect of spontaneous portosystemic shunts on hemorrhage from esophagogastric varices.

The role of a massive spontaneous portosystemic shunt (MSPSS) in cirrhotic patients with portal hypertension remains unclear. The aim of this study was to investigate clinical outcomes and portal hemodynamic changes following ligation of the MSPSS during devascularization surgery. Portography and gastroendoscopy were performed before and after surgery for hemodynamic and follow-up studies. Three types of MSPSS were demonstrated portographically: 22 portoumbilical shunts, 18 splenorenal shunts, and 2 inferior mesenteric-caval shunts. A total of 40 MSPSS patients with esophagogastric variceal (EGV) bleeding underwent surgery: 26 had ligation of the MSPSS, and the remaining 14 served as the nonligation group. Neither the preoperative mean portal pressure (MPP) nor the postoperative MPP were significantly different between the ligation and nonligation groups (p>0.1), and there was no significant difference regarding surgical mortality, recurrent varices, or cumulative survival rate for the two groups in the follow-up study. However, postoperative portography demonstrated persistent drainage of portal flow and decreased intrahepatic portal perfusion in the nonligation patients. Clinical signs of hepatic encephalopathy subsided after ligation of the MSPSS in three patients. Therefore ligation of the MSPSS, which may be responsible for the development of encephalopathy, is recommended during devascularization surgery for EGV in cirrhotic patients.

Adult↗

PubMed2003

High frequency of activated K-ras codon 15 mutant in colorectal carcinomas from Taiwanese patients.

Colorectal carcinogenesis is regarded as a multistep process resulting from accumulation of genetic alterations, including activation of protooncogenes and inactivation of tumor suppressor genes via signal transduction trigger the stage-wise progression to malignancy. The reported incidence of K-ras mutation detected in general tissue samples ranges from 21-60% in primary colorectal cancers (CRC). To assess the prevalence and spectrum of K-ras mutations in Taiwanese patients with CRC, we analyzed 65 CRC patients by polymerase chain reaction-single strand conformation polymorphism analysis, followed by direct sequencing. K-ras mutations were detected in 43.1% (28 of 65) of the tumors. The mutational hot spots were located at codons 12, 13, 15 and 20, especially with the highest frequency at codon 15. To understand whether the codon 15 mutations in CRC were associated with activation of K-ras oncogene and the alterations of its biocharacteristics, mutant K-ras genes were cloned from tumor tissues and then inserted into expression vector pBKCMV to construct the prokaryotic expression plasmid pK15MCMV. Mutant K-ras genes were expressed at high levels in E. coli and the mutant K-ras proteins were shown to be functional with respect to their well-known specific, high-affinity, GDP/GTP binding. The purified K-ras protein from E. coli was then measured for its intrinsic GTPase activity and the extrinsic GTPase activity in the presence of GTPase-activating protein for ras. We found that the extrinsic GTPase activity of the codon 15 mutant K-ras proteins (p21(K-ras15M)) in the presence of GAP is much lower than that of the wild-type K-ras protein (p21 BN), whereas the intrinsic GTPase activity is nearly the same as that of the wild-type K-ras protein. The results indicated that mutation at the codon 15 of K-ras gene indeed decreased GTPase activity in CRC, however, its association with tumorigenesis of CRC needs be clarified by further studies.

Adult↗

PubMed2003

Mutation analysis of the putative tumor suppressor gene PTEN/MMAC1 in advanced gastric carcinomas.

A novel tumor suppressor gene, PTEN/MMAC1, located on chromosome band 10q23.3, encodes a 403-amino acid, dual-specificity protein phosphatase. The defects in this gene are responsible for the development of some advanced cancers. Inactivating alterations, including mutations and deletions, in the PTEN/MMAC1 gene have been identified in several types of human cancers and cancer cell lines. To clarify the participation of the PTEN/MMAC1 gene in advanced gastric carcinogenesis, we screened their frequency of mutations in primary advanced gastric adenocarcinoma tissues. Cancer specimens and their corresponding normal tissues were obtained surgically from 60 patients with pathologically proven advanced gastric carcinoma at the Department of Surgery of Kaohsiung Medical University Hospital. All nine exons of the PTEN/MMAC1 gene were amplified using polymerase chain reaction and screened for mutations by single-strand conformation polymorphism analysis and followed by direct sequencing. After neutral polyacrylamide gel electrophoresis, 17 patients (28.3%) showed an apparent electrophoretic mobility shift between the cancer and its paired normal tissue. These results from direct sequencing indicated that mutations consisted of eight cases (47.1%) of missense mutation, five silent mutations (29.4%), two nonsense mutations (11.8%), a 12-bp deletion (5.9%), and a mutation within the splice donor site of intron 6 (5.9%). The mutation hot spots at codons 45, 66, 82 and 204 in advanced gastric cancer have not been observed previously. Based on the present analysis, our study implicated that the mutations of the PTEN/MMAC1 gene do not occur at a significant rate in human advanced gastric carcinoma, but the rare clustered mutation site (exons 2-6) perhaps suggested that PTEN/MMAC1 might contribute to the gastric carcinogenesis and its progression.

Adenocarcinoma↗

PubMed2003

Overexpression of inducible nitric oxide synthase in gastric mucosa of rats with portal hypertension: correlation with gastric mucosal damage.

BACKGROUND: An increased biosynthesis of nitric oxide (NO) has been implicated in the hyperdynamic circulation and development of collaterals of portal hypertension (PHT) because of its potent vasodilatory effects. NO is synthesized from L-arginine by three different isozymes of nitric oxide synthase (nNOS, iNOS and eNOS). Thus, the expression of inducible NOS (iNOS) might account for NO overproduction in PHT. However, in previous investigations, the role of iNOS in the pathogenesis of PHT gastropathy remained controversial. Our current study was in both molecular and protein levels to determine whether the expression of iNOS is responsible for PHT gastropathy. MATERIALS AND METHODS: PHT was induced experimentally by partial ligation of the portal vein. Fourteen days after partial ligation of the portal vein, the rats were randomly assigned to receive either vehicle or L-NAME (NOS inhibitor) at doses of 5 mg/kg/day, 10 mg/kg/day, or 25 mg/kg/day by gastric lavage twice a day for 1 week. Sham operated rats served as controls. Northern hybridization and in situ hybridization are used to compare the expression of gastric mucosa iNOS mRNA in the PHT rats and the controls. NO was measured by the Griess method after reduction of nitrate to nitrite with nitrate reductase. Immunohistochemical staining was carried out to detect the iNOS protein. In addition, the severity of gross gastric mucosal lesions was evaluated macroscopically by a gross ulcer index. RESULTS: The iNOS expression at both mRNA and protein was prominently increased in PHT rats, accompanied with the enhanced NO production. The gastric mucosa iNOS mRNA and serum NO levels were significantly decreased after L-NAME administration (P < 0.05). However, the markedly reduced gastric mucosal damage in PHT rats was observed only at high does of L-NAME (25 mg/kg/day) administration. CONCLUSION: PHT triggers overexpression of iNOS mRNA and proteins in rat gastric mucosa, but that this alone does not account for PHT gastropathy.

Animals↗

PubMed2002

Rectal perforation secondary to surgical drains after low anterior resection: a report of two cases and review of the literature.

Routine pelvic drainage after resection of the rectum followed by immediate anastomosis is not only advisable but also essential for decreasing fluid accumulation and subsequent abscess formation. In spite of infrequency, complications secondary to placement of these surgical drains occur. Herein we report two cases of rectal perforation caused by prophylactic drainage of pelvic cavity after low anterior resection for rectal carcinoma. Postoperatively, both patients were found with discharge of faecal material from the surgical drains. Anastomotic dehiscence was tentatively impressed until a definite diagnosis was obtained. The drain tube penetrated into the rectal lumen without anastomotic leakage and that was ultimately confirmed by colonoscopy. The possibility of rectal perforation should be kept in mind when draining the pelvic cavity after low anterior resection for the rectal carcinoma. Furthermore, significance of colonoscopy in the early postoperative period should be emphasized.

Aged↗

PubMed2002

Emergency one-stage surgery for obstructing left-sided colorectal carcinomas.

A one-stage operation for obstructing left-sided colorectal carcinoma remains controversial. This study was performed to compare our surgical management of patients with left-sided colorectal cancer (at or distal to splenic flexure) obstruction presenting to the Kaohsiung Medical University Hospital from January 1995 to December 2000. Ninety-six patients underwent immediate operation within 24 hours of admission. Of these, 73 patients (76%) who underwent immediate tumor resection and anastomosis in one stage after appropriate resuscitation were enrolled into our study. In one-stage operation subtotal coloectomy with ileocolic or ileorectal anastomosis (group 1) was performed in 46 patients (63%), and intraoperative bowel preparation followed by immediate resection (group 2) was undertaken in 27 patients (37%). In comparing the two groups, there was no significant difference in the postoperative mortality (8.7% in group 1 vs. 7.4% in group 2) or cumulative 5-year survival rate (36.7% in group 1 vs. 35.7% in group 2) (all p > 0.05). However, mean operation time (178 +/- 12 min in group 1 vs. 238 +/- 12 min in group 2) and postoperative wound infection rate were significantly lower (10.9% in group 1 vs. 29.6% in group 2). The incidence of postoperative diarrhea was more prominent in the group 1 than group 2 (32.6% in group 1 vs. 11.1% in group 2) (all p < 0.05). The results of our current study showed that primary resection and anastomosis by subtotal colectomy is an acceptable means for the treatment of patients with obstructing left-sided colorectal carcinomas when the patient's condition is feasible.

Adult↗

PubMedDate not supplied

Directional shape complementarity at the protein-DNA interface.

Nature utilizes various styles of architecture for DNA-binding proteins to recognize diverse DNA sequences, a process facilitated by a complementary surface between protein and DNA. However, the extent and ways this 'shape complementarity' occurs at the protein-DNA interface have yet to be characterized. Here, by analyzing a set of diverse protein-DNA complexes of known three-dimensional structures, we investigated whether the normal vectors of a protein surface at the interface exhibited any relationship with DNA conformation. Generally, the normal vectors of a DNA-contacting protein surface distinctly preferred certain angles, enabling them to align with certain axes characterizing the conformation of DNA. Thus, a new geometric property of DNA-binding protein is demonstrated, i.e. the "shape complementarity" of protein-DNA recognition clearly bears the property of "directionality".

DNA↗

PubMedDate not supplied

The effect of portal hypertension on the glycoprotein biosynthesis of rat gastric mucosa.

The aim of this study was to assess the influence of epidermal growth factor (EGF) on glycoprotein biosynthesis in portal hypertensive (PHT) gastric mucosa. Portal-vein ligation (PVL) for a period of 4 weeks was applied to 40 male Wistar rats to produce experimental portal hypertension. The rats were subdivided into four groups. Human EGF was administrated to these four groups of animals at a does of 0, 10, 25, and 50 microg/kg/day for 7 days. An additional group of 10 rats without PVL and EGF pretreatment was employed as a control. The severity of gross gastric mucosal lesions was evaluated macroscopically by a gross ulcer index. Glycoprotein biosynthesis of the gastric mucosa was determined by the incorporation rate of [(3)H]glucosamine. Quantitative changes of gastric mucosal hexosamines were also used for mucosal glycoproteins analyses. The gross mucosal damage was considerably greater in the PVL group without EGF pretreatment than in the EGF-pretreated groups (p <.05). The incorporation rate of [(3)H]glucosamine was significantly higher in the control group and the EGF-pretreated groups than in the PVL group without EGF pretreatment (p <.05). Moreover, the incorporation rate of [(3)H]glucosamine and the gastric mucosal hexosamine content were closely relevant to administration does of human EGF (p <.001). In addition, the reduction of glycoprotein biosynthesis was closely related to the increase in portal pressure (p =.001) and the severity of portal hypertensive gastropathy (p <.001). Our current study shows that the rate of incorporation of glucosamine is decreased in the PHT gastric mucosa and that EGF significantly stimulated glycoprotein synthesis in the PHT gastric mucosa. Accordingly, these findings may be helpful to explain the protective effect of EGF on the PHT gastric mucosa via increased glycoprotein biosynthesis in the stomach.

Animals↗

PubMedDate not supplied

A comparative study of pancreatectomy and pancreas-preserving gastrectomy in advanced gastric carcinomas.

BACKGROUND/AIMS: In patients with advanced gastric carcinoma (tumor infiltrating beyond submucosal layer), distal pancreatectomy has been frequently performed simultaneously with gastrectomy for complete removal of the lymph nodes along the splenic artery. However, the possibility of a negative impact has also been reported. To evaluate the effects of distal pancreatectomy with gastrectomy for patients with advanced gastric cancer, we retrospectively analyzed 84 patients who had proximal- or middle-third advanced gastric cancer resected in an institution in Taiwan. METHODOLOGY: From 1988 to 1998, 46 patients who underwent gastrectomy with distal pancreatectomy (DP group) and 38 patients who had pancreas-preserving gastrectomy (PS group) for advanced gastric cancer were reviewed. The clinicopathological details and survival rates were compared between the two groups. RESULTS: In terms of clinicopathological factors and operative mortality, there were no significantly statistical differences between the patients who did and did not undergo distal pancreatectomy. The cumulative 5-year survival rate for the DP group was 35.6%, whereas the 5-year survival rate for the PS group was 42.4% (P=0.6224). In contrast, the operative morbidity was significantly higher in patients who had distal pancreatectomy (P=0.008). CONCLUSIONS: Since distal pancreatectomy does not benefit patients with advanced gastric cancer, this procedure should not be regarded as routine in a radical resection.

Carcinoma↗