Biomedical subjects

Jian-ping Wang

Publications and source records attributed to Jian-ping Wang.

36 records · Page 2Linked to original sources

PubMed2005

[Parameter optimization of water quality model: implementation of genetic algorithm and its control parameters analysis].

Parameter identification plays an important role in environmental model application. As a commonly used global optimization method, genetic algorithm (GA) has very simple structure, the key related to whether a practical issue can be solved using GA or not is algorithm design and selection of the control parameters. Based on the feature of parameter optimization of water quality model, orthogonal test method was proposed for reviewing effects of different control parameters of GA on the performance of water quality parameter optimization. The results indicate that orthogonal method could identify key factors, and also provide possible optimized experiment plan. It is concluded that GA can be applied to the research on parameter identification of complicated water quality model.

Algorithms↗

PubMed2005

[Clinical analysis of multiple primary carcinomas in colorectal cancer patients].

OBJECTIVE: To explore the prevalence, clinical features and prognosis of multiple primary neoplasms in patients with colorectal carcinoma (CRC). METHODS: Data of colorectal cancer patients admitted to our hospital from June 1994 to June 2002 were analyzed retrospectively. Patients were divided into multiple-cancer group (MCG) and single- cancer group (SCG). Clinical features and prognosis were compared between two groups. RESULTS: The incidence of multiple cancers was 7.4 % (83/ 1125). Forty- seven patients had multiple colorectal cancers metachronous CRC(S) in 12 and synchronous CRC(S) in 35. Thirty- six patients 5 patients with synchronous cancers had malignant tumors outside colorectal tract,12 of whom were gastric carcinomas. No significant differences were found between MCG and SCG regarding gender, onset age, Dukes stage and differentiation of index CRC. Cancer family history (P=0.002) and colorectal adenoma (P=0.036) were significantly more common in MCG than those in SCG. The local recurrence or distant metastasis in MCG was significantly higher than that in SCG (P=0.047), though there was no significant difference in survival between the two groups. Forty- one percent of index tumors were located in right colon in MCG, significantly higher than that in SCG (P=0.048). The secondary tumors were mainly adenoma cancerization in MCG. CONCLUSION: Cancer family history and colorectal adenoma seems to be at high risk for developing multiple cancers in CRC patients. Gastric cancer and colorectal adenoma cancerization were common secondary tumors of multiple primary neoplasms in patients with colorectal carcinoma.

Adenomatous Polyps↗

PubMed2005

[Comparison of the efficacy and safety of compound carraghenates cream and compound carraghenates suppository in the treatment of mixed hemorrhoids].

OBJECTIVE: To evaluate and compare the efficacy and safety of titanoreine cream with compound carraghenates suppository in the treatment of mixed hemorrhoids. METHODS: Two hundred and fifty-two patients with mixed hemorrhoids were enrolled in this randomized,open, multicentral trial. Patients applied titanoreine cream (study group, n=133) or compound carraghenates suppository (control group, n=119). The symptomatic relief including pain,bleeding and edema was evaluated by scoring system at 30 minutes, 3 hours, 6 hours, 1 day, 2 days, 3 days, 4 days, 6 days after administration. RESULTS: Symptoms were significantly improved in both groups (87.3%, 94.8%, respectively) excepting symptom of pain relief, but there was no significant difference between two groups (P > 0.05). The pain scores were lower at every observing point in the study group than those in the control group (P< 0.05). The proportions of the patients with pain relief and all symptoms relief were both higher in the study group than that in the control group at 30 min, 3 h after drug used (both P< 0.01). No side effect was found during the triad. CONCLUSION: Titanoreine cream has predominance of relieving pain and response time compared with compound carraghenates suppository, but other effects on mixed hemorrhoid are similar between the two groups.

Adult↗

PubMed2005

[Indications and prognostic analysis of sphincter preservation operation for rectal cancer].

OBJECTIVE: To explore the indications of sphincter preservation operation (SPO) for rectal cancer, and factors influencing selective indications of SPO. METHODS: From April 1994 to April 2004, clinical data of 708 cases with rectal cancer were analyzed retrospectively. The patients received either SPO (SPO group, n=481) or abdominoperineal resection (APR group, n=227). Clinical pathologic parameters and survival rate were compared between the two groups. RESULTS: There were 66 patients with tumor located in sigmoid-rectum borderline, 138 in upper rectum, 195 in middle rectum, 309 in lower rectum. Dixon operation was performed in 449 patients, Bacon operation in 12, and "J" Poch anastomosis in 20 and Hartman operation in 13. There was no differences in sex, ages, liver metastasis, size, depth of invasion and Dukes stages between APR and SPO groups, but there was significant difference in lower bowel obstruction, tumor location, differentiation degree, infiltrated circumference of intestine, lymph node metastasis and radical approaches between the two groups. Radical excision was performed in 660 rectal cancer cases with radical excision rate of 91.5% . SPO was performed in 481 cases with preservation rate of 66.7%, including 135 lower rectal cancer with preservation rate of 43.7%. The operative mortality was 0.4% (3/708), regional recurrence rate was 5.51% (39/708) after operation. The median survival time was (65.0+/- 6.9) months in SPO group and (42.2+/- 5.6) months in APR group (P< 0.01), the 5-year survival rate was 59.3% and 42.3% in SPO and APR group (P< 0.001). CONCLUSIONS: SPO should be considered as primary choice for rectal cancer patients, but it must be ensured that complete radical resection be performed. Indications for SPO in lower rectal cancer depend on tumor location,differentiation degree,and infiltrated circumference of intestine,lymph node metastasis.

Anal Canal↗

PubMed2005

[Haplotype and linkage analysis in Chinese hereditary mixed polyposis syndrome].

OBJECTIVE: To investigate if hereditary mixed polyposis syndrome (HMPS) locus of two Singapore Chinese HMPS families is identical with the Ashkenazi families. METHODS: Genomic DNA was extracted, multiplex polymerase chain reaction (PCR) was used to amplify 4 microsatellite markers D15S1010, D15S1007, ACTC and D15S118 in 31 individuals from two families. The HMPS locus cosecretion of the markers on 15q13 over a region of 2.8 cM was confirmed by Haplotype and linkage analysis. RESULTS: The disease of haplotype identified in one pedigree was not co-segregated with an affected individual while no definitive disease haplotype could be assigned for the second pedigree. The maximum two-point and multi-point LOD scores at ACTC for the two Chinese families are 0.20 (theta = 0.3) and -5.0 respectively. CONCLUSIONS: Haplotype and linkage analysis indicate that the Ashkenazi haplotypes is not associated with HMPS in Singapore Chinese families, which suggests genetic heterogeneity.

Adenomatous Polyposis Coli↗

PubMed2005

[Radical resection of gastric or colorectal carcinoma combined with liver transplantation for gastric or colorectal carcinoma with multiple hepatic metastases].

OBJECTIVE: To summarize the short-term outcomes of radical resection of gastric or colorectal carcinoma combined with liver transplantation for gastric or colorectal carcinoma with multiple hepatic metastases. METHODS: Radical resection of gastric or colorectal carcinoma combined with liver transplantation were performed on one gastric carcinoma case and two rectal carcinoma cases with severe liver metastasis, and partial resection of left lung was performed in one of the two rectal cancer cases for pulmonary tuberculosis. RESULTS: There was no perioperative death. The gastric cancer patient died of recurrence 5 months after operation. The rectal cancer patient with pulmonary tuberculosis died of hepatic function failure 7 months after operation without recurrence. Another rectal cancer patient recovered well with normal liver functions, blood cells, without recurrence signs, and was back to work. CONCLUSION: Radical operation combined with liver transplantation may provide survival opportunity for some patients with gastric or colorectal carcinoma synchronous with severe liver metastasis, but the long-term outcome needs to be observed.

Colorectal Neoplasms↗

PubMed2005

[Migration characteristics of heavy metals during sintering of fly ash from municipal solid waste incinerator].

The sintering process is used to stabilize the heavy metal in fly ash from municipal solid waste incinerator (MSWI). Migration characteristics of 6 targeted heavy metals (Cd, Pb, Cu, Ni, Cr and Zn) in the sintering process of MSWI fly ash were investigated by experiments. Effect of several factors including sintering temperature, residence time, molding pressure and particle diameter on the migration of heavy metals were discussed in details. The results show that cadmium and lead are volatile metals, while nickel, copper, chromium and zinc belong to involatilizable metals. The effects of sintering temperature, residence time, molding pressure and particle diameter on the stabilizing efficiency differ from each other. The study shows that most of heavy metals are stabilized during the sintering process. The stabilizing efficiency of heavy metals was different for different elements.

Air Pollutants↗

PubMed2005

[Study on the postive frequency and distribution of glutamic acid decarboxylase antibody in phenotypic type 2 diabetec patients].

OBJECTIVE: To investigate the positive frequency and distribution of glutamic acid decarboxylase antibody(GAD-Ab) in phenotypic type 2 diabetic(T2DM) patients. METHODS: Sera of 2035 phenotypic T2DM patients were screened for GAD-Ab with radioligand assay. The positive frequency of GAD-Ab and its relation with clinical features were analyzed. RESULTS: (1) The positivity of GAD-Ab in clinic-based, phenotypic T2DM patients was 7.1% (145/2035), comparable to that of data from Caucasians as shown by UKPDS(8.7% vs. 9.8%, P = 0.391) and ADOPT (8.0% vs. 4.2%, P = 0.000) but higher than that of Japanese in Ehime study(7.1% vs. 3.8%, P = 0.000). (2) The positive frequency and distribution of GAD-Ab titer were related to clinical features, including age at onset, body mass index (BMI) and fasting C peptide levels. Patients with younger age at onset (0.33 vs. 0.11, P < 0.05), less BMI (0.34 vs. 0.10, P < 0.05) and lower C peptide levels (0.38 vs. 0.11, P < 0.05) would have higher GAD-Ab titers. CONCLUSION: (1)The positivity of GAD-Ab in adult-onset phenotypic T2DM in Chinese was similar to that of Caucasians but higher than that of the Japanese. (2) The distribution of GAD-Ab titers was associated with clinical features, with high GAD-Ab titers for those having younger age at onset, less BMI and lower C peptide levels.

Adolescent↗

PubMed2004

[Etiological dissection in common anti-islet autoantibody-negative patients with type 1 diabetes].

OBJECTIVE: To explore the immunological and genetic factors of common anti-islet autoantibody-negative patients with type 1 diabetes. METHODS: Specimens of peripheral blood were collected from 33 common autoantibody (GAD-Ab, IA2-Ab, IAA, TGA and TPO-Ab) negative diabetic patients with new-onset of unprovoked ketosis (or ketoacidosis), and genome DNA was extracted. The antibodies to carboxypeptide-H (CPH) and SOX13 (ICA12) were detected by radioligand assay. The gene mutations of MODY3 (HNF-1alpha) and MODY6 (NeuroD1/Beta2) were detected by PCR-SSCP sequencing. Mitochondrial gene mutations were analyzed with PCR-RFLP. RESULTS: Two (6%) of the patients were SOX13-Ab positive, while none of them was positive for CPH-Ab. Gene mutation detection found one case of a new mutation, R321H (CGC-->CAC) in the exon 5 of HNF-1alpha gene and one case with ND1 mt3316 G-->A mutation in mitochondrial DNA. In addition to the diabetes-associated mutations described above, seven polymorphisms of HNF-1alpha gene, including L17L, I27L, L459L, S487N, IVS5 + 9 C > G, IVS6-42 G > T, and IVS7 + 7 G > A, and one NeuroD1/Beta2 gene polymorphic variant Ala45Thr, were found. CONCLUSION: Autoimmunity and gene mutations (such as MODY3 and mitochondrial genes mutations) may be etiological in a few cases initially diagnosed as autoantibody-negative type 1 diabetes. Autoimmunity and MODY and mitochondrial diabetes should be excluded if idiopathic type 1 (type 1B) diabetes is diagnosed.

Adolescent↗

PubMed2004

[Subclassification of seronegative type 1 diabetic subjects with HLA-DQ genotypes].

OBJECTIVE: To reveal the relationship between disease phenotype and HLA-DQ genotype in autoantibody-negative type 1 diabetics and to explore whether HLA-DQ genotypes can reclassify seronegative type 1 diabetic patients. METHODS: Sixty-one diabetics with unprovoked ketosis or ketoacidosis at presentation were tested for glutamic acid decarboxylase antibody (GAD-Ab), tyrosine phosphatase antibody (IA2-Ab), thyroglobulin antibody (TGA), thyroid peroxidase antibody (TPO-Ab) and HLA-DQ genotype. GAD-Ab and IA2-Ab were measured with radioligand assay. TGA and TPO-Ab were evaluated using RIA. Sequence-based genotyping (SBT) was used to determine the alleles of HLA-DQA1 and DQB1. Autoantibody negative patients were subdivided into group A (with type 1 diabetes susceptible alleles) and group B (without type 1 diabetes susceptible alleles). Clinical characteristics, including age, sex, mode of presentation, body mass index (BMI), islet beta-cell function and current treatment were compared between the autoantibody-positive and autoantibody-negative patients and between group A and B. RESULTS: Among the 61 patients, 29 (47.5%) were negative for all the antibodies tested, while 31 (50.8%) were positive for one or more antibodies tested. 5 (8.2%) were positive for all those 4 antibodies. As for genetic analysis, 18 of the 29 seronegative patients carried 1-4 HLA-DQ risk alleles, while the other 11 did not carry any type 1 diabetes susceptible alleles tested. As compared with the autoantibody-negative patients, younger age at onset, less obesity, severer degree of diabetic ketoacidosis (DKA) and lower C peptide were found in the autoantibody-positive ones. As compared with group B, less obesity [BMI: (22.4 +/- 4.4) kg/m(2) vs (25.8 +/- 3.7) kg/m(2), P = 0.03], severer degree of DKA [CO(2)CP: (16.3 +/- 7.1) mmol/L vs (19.2 +/- 2.0) mmol/L, P = 0.01; pH: 7.26 +/- 0.20 vs 7.34 +/- 0.06, P = 0.03], and lower C peptide [fasting C peptide: (254.6 +/- 189.4) pmol/L vs (458.7 +/- 274.1) pmol/L, P = 0.06] were observed in group A. During follow-up, 73% (8/11) patients in group B discontinued insulin therapy and maintained acceptable glycemic control by either diet or oral hypoglycemic agents (OHA), while only 28% (5/18) of the patients in group A discontinued and maintained control with OHA (28% vs 73%, P < 0.01). Among those who kept on using insulin, group A patients required higher insulin dosage than those of group B [(0.43 +/- 0.16) U x kg(-1) x d(-1) vs (0.24 +/- 0.18) U x kg(-1) x d(-1), P = 0.07]. CONCLUSIONS: Autoantibody-negative diabetics, if with susceptible HLA-DQ genotypes, presented more type 1A-like features, implying possible existence of as yet unidentified immunologic abnormalities in these patients. HLA-DQ risk genotypes may reclassify seronegative type 1 diabetics. Those who are autoantibody negative but carry susceptible HLA-DQ genotypes, should not be diagnosed as type 1B diabetes.

Adolescent↗

PubMed2004

[Adult-onset latent autoimmune diabetes and autoimmune thyroid disease].

OBJECTIVE: To investigate the relationship between latent autoimmune diabetes in adults (LADA) and thyroid autoimmunity. METHODS: The frequency of thyroid peroxidase antibody (TPO-Ab) and thyroglobulin antibody (TG-Ab) was determined with radioimmunoassay in 394 subjects, including 90 LADA, 104 classic type 1 diabetics (T1DM), 100 type 2 diabetics (T2DM) and 100 controls. Glutamic acid decarboxylase antibody (GAD-Ab) was measured with radioligand immunoassay. RESULTS: (1) TPO-Ab existed more frequently in LADA (16.7%, 15/90) than in T2DM patients (7.0%, 7/100; P < 0.05). The frequency of thyroid antibody (TPO-Ab or TG-Ab positivity) in LADA and T1DM was 18.9% (17/90) and 25.0% (26/104) respectively, being higher than that in the control group (8/100, 8.0%; P < 0.05). (2) Thyroid antibodies occurred more frequently in LADA patients with higher titer of GAD-Ab (GAD-Ab > or = 0.5) than those with lower ones (50.0% vs 12.5%, P < 0.05). (3) 47.1% (8/17) of LADA patients with thyroid autoimmunity had thyroid dysfunction as compared with 17.6% (6/34) in the group without thyroid antibodies (P < 0.05). CONCLUSIONS: (1) LADA patients, especially those with high titer of GAD-Ab, have high risk for thyroid autoimmunity. (2) The presence of thyroid antibody may predict high risk for thyroid dysfunction in LADA patients. (3) LADA may be one of the components in autoimmune polyendocrine syndrome.

Adolescent↗

PubMed2004

Lipoprotein glomerulopathy: clinical features and pathological characteristics in Chinese.

BACKGROUND: Lipoprotein glomerulopathy (LPG), once recognized as a rare glomerular disease, has been reported around the world in recent years. In this study, we reported 8 patients of LPG and aimed to explore the clinical features and pathological characteristics of LPG under light microscope, immunofluorescence staining, and electron microscope. METHODS: Clinical manifestations were recorded on the day of renal biopsy. Biochemical patterns of lipids and lipoproteins were detected by routine examination. Plasma concentrations of apo B and apo E were determined by radial immunodiffusion assays. Biopsy specimens were then processed for light microscopy, immunohistochemical staining for immunoglobulins and complement components, and electron microscopy. Glomerular deposition of apo A, B, and E were detected using monoclonal antibodies on cryostatic sections. RESULTS: All of the eight patients presented with edema, microscopic hematuria, severe proteinuria, anemia, and enlarged kidney size. Biochemical profiles revealed high levels of triglycerides, apo B, and apo E. We noted increments of glomerular size and lipoprotein thrombi occupying capillary lumina in the glomeruli of all patients. Immunofluorescence staining showed that the thrombi were strongly positive for apo A, B, and E. Granules and various sizes of vacuoles were observed in the thrombi under electron microscope. CONCLUSION: Compared with previous reports on LPG in other countries, unique clinical and pathological features were found in this group of Chinese LPG patients.

Adolescent↗

PubMed2004

[Construction and identification of anti-chymopapain scFv phage display library].

AIM: To construct phage display library of anti-chymopapain scFv. METHODS: V(H) and V(L) gene repertoires were amplified from splenocyte mRNA by RT-PCR and joined by a (Gly(4)ser)3 linker to obtain scFv genes. The scFv genes were then cloned into phagemid pFAB5C to construct phage display library. Affinity selection and ELISA were used to identify specific phage antibody to chymopapain. RESULTS: After 4 rounds of panning, high affinity scFv was obtained. CONCLUSION: Phage display library of anti-chymopapain scFv was successfully constructed, and scFv with binding ability to chymopapain was obtained.

Animals↗

PubMed2004

[Relationship between heparanase mRNA expression in human gastric cancer and its clinicopathological features].

OBJECTIVE: To explore the relationship between heparanase mRNA expression and clinicopathological parameters in human gastric cancer. METHODS: RT-PCR was used to detect the expression of heparanase mRNA in 43 human gastric carcinomas and 10 adjacent normal gastric tissues. RESULTS: Heparanase mRNA was expressed in 29 of the 43 cases of gastric cancer with a positive rate of 67.4%, which was significantly higher than that in adjacent normal gastric tissues (P = 0.013). The expression level was higher in late-stage tumors (stage III and IV) than in early-stage tumors (stage I and II) (P = 0.001), in tumors with invasion to serosa than those without serosal invasion (P = 0.009), in tumors with lymph node metastasis than those without lymph node metastasis (P = 0.018), and in large-sized tumors than in small-sized ones (P = 0.009). The expression was not correlated with patients' age, sex, tumor location, histologic types, differentiation, peritoneal dissemination and liver metastasis (P > 0.05). CONCLUSION: Heparanase might play an important role in the development of invasion and metastasis of gastric cancer.

Adenocarcinoma↗

PubMed2003

[Multi-variate regression analysis of clinicopathological characteristics and prognosis of colorectal cancer].

OBJECTIVE: To evaluate the relationship between clinicopathologic features and prognosis of colorectal cancer after surgical treatment. METHODS: The clinical characteristics, pathologic features and survival rate of 761 patients with colorectal cancer after surgical treatment were univariately and multivariately analyzed. RESULTS: The overall 3- and 5-year survival rates of patients with colorectal cancer after surgical treatment were 62.9% and 60.7% with a median survival of 1,825 days. The factors of gross findings, degree of differentiation, infiltration, nodal and distant metastasis and neoplastic intestinal obstruction influenced the survival rate by univariate analysis. The factors of Dukes stage, gross tumor configuration, intramural spread and differentiation degree were available independent prognostic factors through multivariate analysis. CONCLUSION: Dukes stage, as the most important available independent prognostic factor (P < 0.0005), is able to assess the postoperative survival.

Adult↗

PubMed2003

[Clinical values of palliative gastrectomy for late-staged gastric cancer].

OBJECTIVE: To investigate the clinical importance of palliative gastrectomy for late-staged gastric cancer. METHODS: From June 1994 to October 2001, 95 patients with late-staged gastric cancer underwent palliative operation. Clinicopathological and prognostic parameters between 64 patients with palliative gastrectomy (PG group) and 31 patients with unresectable operation (UO group) was compared retrospectively. RESULTS: The age and gender ratios were not different between the two groups. The incidence of large volume (diameter > or = 8 cm), serosal invasion (T(4)) and late TNM stage (IV stage) were significantly higher in the UO group than that in the PG group. There was no difference in peritoneal dissemination, distant lymph node and hepatic metastasis, and tumor location between the two groups. The one- and two-year survival of the patients in the PG group was 48.1% and 23.1%, and significantly better than 13.5% and 0 in the UO group. CONCLUSIONS: Palliative gastrectomy, compared with unresectable operation, can improve the prognosis of the patients with late-staged gastric cancer even with peritoneal dissemination, distant lymph node and hepatic metastasis, and surrounding organ invasion.

Adult↗

PubMed2003

[Synergistic protective effect of testicular cells expressing Fas ligand and cyclosporine A on the survival of islet allografts].

OBJECTIVE: To explore the synergistic protective effect of co-transplanted testicular cells expressing FasL and CsA on survival of islet allografts. METHODS: The allogeneic islets and testicular cells were co-transplanted into the renal subcapsular space of the diabetic recipients with or without CsA after operation. Allografts survival period and the testicular cells or islets function were analyzed. RESULTS: The mean survival period of control group was 4.6 +/- 1.1 days. When CsA was administered after transplantation, the mean survival period of islet allografts, (21.8 +/- 4.7) days, was significantly longer than that of control group (P < 0.01). When islets were co-transplanted together with 1 x 10(7) testicular cells (group A), a significant prolongation of graft survival was found (more than 57.5 +/- 4.0 days; P < 0.01 vs. control). But if 1 x 10(7) testicular cells expressing FasL were cultured with FasL-mAb for 30 minutes before co-transplantation (group B), the mean survival period of islet allografts (5.8 +/- 2.6 days), was similar to that in control group, but significantly shorter than that in group A (P < 0.01). When islets and 1 x 10(5) testicular cells were co-transplanted separately into the bilateral renal subcapsular space with CsA (group C), the survival of islet allografts was significantly prolonged in comparison with control group (more than 55.0 +/- 6.5 days; P < 0.01 vs. control), and similar to islets co-transplanted together with 1 x 10(7) testicular cells (group A). When islets were co-transplanted separately with 1 x 10(6) testicular cells without CsA (group D), the mean survival period (11.5 +/- 3.1 days) was shorter than that in group C, but prolonged in comparison to control group (P < 0.05). CONCLUSION: The co-transplanted testicular cells expressing FasL with administering CsA post-transplantation can jointly inhibit immune rejection of islet allografts by different mechanism and play a systemic and synergistic protective role to islet allografts.

Animals↗

PubMed2002

[The roles of DNA methylation in human neoplasms].

Recent data suggested that cancer appears to be a process that is fuelled both by genetic alterations and by epigenetic mechanisms. Epigenetics refer to the study of changes in gene expression that can be mitotically inherited, but is not associated with the changes in the coding sequence of the affected genes. DNA methylation, the best understood mechanism in epigenetics, is an enzyme-mediated chemical modification that adds methyl (CH3) groups at selected sites on DNA. In humans and most mammals, DNA methylation only affects the cytosine base (C), when it is followed by a guanosine (G). DNA methylation in the promoter regions is a powerful mechanism for the suppression of gene activity. It was thought formerly that two pathways by which tumor suppressor genes became disabled were intragenic mutations and loss of chromosomal material [(loss of heterozygosity (LOH) or homozygous deletion)]. More recent studies have firmly established methylation as one potential hit and represent a third mechanism by which tumor suppressor genes are inactivated, and that, in some cases, methylation is the sole mechanism responsible for the inactivation of a tumor suppressor gene. There is clearly a tumor-specific methylation pattern in many types of tumor. An individual tumor within a single patient may have characteristic set of gene with an increased propensity to become methylated as compared with a tumor of the same type in a different patient. Methylation changes appear to precede apparent malignancy in many cases. Therefore, methylation can distinguish tumor types and subtypes, and should be useful in improving early detection of potentially cancerous cells. Methylation markers may also be used to predict response to chemotherapy or duration of patient survival. The efficacy of hypomethylating agents (e.g. 5-aza-2'-deoxycytidine) as antineoplastic agents has been attributed to two distinct mechanism: cytotoxicity and induction of hypomethylation. Some clinical trials with them have been performed in solid tumors and malignant hematologic disease. In general, the response rates were not satisfactory. A variety of methods are used to evaluate the methylation status of genes. MSP (methylation-specific PCR) is very sensitive and has been widely used. It takes advantage of the DNA sequence difference existing between methylated and unmethylated DNA after bisulfite treatment.

CpG Islands↗