Genetic Heterogeneity of Variable Number Tandem Repeats in Thymidylate Synthase Gene in Colorectal Cancer Patients

2004 ◽  
Vol 19 (4) ◽  
pp. 332-336 ◽  
Author(s):  
M. Agostini ◽  
S. Pucciarelli ◽  
P. Calandra ◽  
F. Villani ◽  
M. Lise ◽  
...  
Keyword(s):  
Thymidylate Synthase ◽  
Tandem Repeats ◽  
Colorectal Adenocarcinoma ◽  
Variable Number ◽  
Mismatch Repair Genes ◽  
Pcr Product ◽  
Group A ◽  
Microsatellite Stability ◽  
Group B ◽  
Repair Genes

Purpose To analyze the genetic variability in a variable number of tandem repeats (VNTR) in the thymidylate synthase (TS) enhancer promoter region and assess the influence of functional alterations in mismatch repair genes by analyzing constitutional and tumoral DNA from patients with colorectal adenocarcinoma with a high microsatellite instability (MSI-H) or microsatellite stability (MSS) status. Patients and methods Patients who underwent surgery for colorectal adenocarcinoma were selected from the colorectal database of our institute and, on the basis of MSI status, assigned to a study group and a control group: group A, MSI-H; group B, MSS. Microsatellite status was investigated using the Bethesda recommended panel (BAT-26, BAT-25, D2S123, D5S346, D17S250). In MSI-H patients an additional analysis was made of the microsatellite loci D18S61 and D18S58, both mapping in the region containing the TS gene (18p11.2–11.32). Based on the number of altered microsatellites (≥2, 1, or 0), tumors were considered as having high (MSI-H) or low (MSI-L) instability or microsatellite stability (MSS), respectively. Genotyping for thymidylate synthase promoter polymorphism was carried out on constitutional and tumor DNA of each patient by PCR amplification of the polymorphic region. Results MSI-H was found in 55 patients (group A) and MSS in 50 patients (group B). In none of the MSI-H patients was microsatellite instability found in the additional D18S61 and D18S58 loci. In five group A and ten group B cases the analysis was not performed because constitutional DNA and/or tumoral DNA were not amplifiable. Homozygotes for the triple repeat variant (3R/3R) displayed only the large PCR product, homozygotes for the double repeat variant (2R/2R) displayed only the smaller PCR product, while heterozygotes (2R/3R) displayed both the larger and smaller PCR products. In 3/50 (6%) group A patients and 5/40 (12%) group B patients repeat variations were found in tumoral DNA. Conclusion Our findings demonstrate that there is genetic homogeneity between constitutional and tumoral DNA but do not support the hypothesis that mismatch repair genes are involved in VNTR recombinant events in TS gene variability.

scholarly journals Phenotypic and Genotypic Characterization ofMycobacterium africanum Isolates from West Africa

1999 ◽  
Vol 37 (6) ◽  
pp. 1921-1926 ◽  
Author(s):  
Richard Frothingham ◽  
Percy L. Strickland ◽  
Gisela Bretzel ◽  
Srinivas Ramaswamy ◽  
James M. Musser ◽  
...  
Keyword(s):  
Sierra Leone ◽  
Tandem Repeats ◽  
Drug Resistant ◽  
Polymorphic Genes ◽  
Intergenic Regions ◽  
Group A ◽  
Definition Of ◽  
Group B ◽  
Vntr Analysis ◽  
Simple Definition

The Mycobacterium tuberculosis complex includesM. tuberculosis, M. bovis, M. africanum, and M. microti. Most clinical isolates areM. tuberculosis or M. bovis. These species can be distinguished by phenotypes and genotypes. However, there is no simple definition of M. africanum, and some authors question the validity of this species. We analyzed 17 human isolates from Sierra Leone, identified as M. africanum by biochemical and growth characteristics. We sequenced polymorphic genes and intergenic regions. We amplified DNA from six loci with variable numbers of tandem repeats (VNTRs) and determined the exact number of repeats at each locus in each strain. All M. africanumisolates had the ancestral CTG Leu at katG codon 463. Drug-resistant M. africanum isolates had katGand rpoB mutations similar to those found in drug-resistantM. bovis and M. tuberculosis. Fourteen Sierra Leone M. africanum isolates (designated group A) hadkatG codon 203 ACC Thr, also found in M. africanum T (the T indicates type strain) from Senegal. Group A isolates clustered with M. africanum T by VNTR analysis. Three M. africanum isolates (group B) had katG codon 203 ACT Thr, found in M. tuberculosis T, and clustered with M. tuberculosis T by VNTR analysis. Phenotypic identification of M. africanumyielded a heterogeneous collection of strains. Genotypic analyses identified a cluster (M. africanum group A) which includedM. africanum T and was distinct from the rest of the M. tuberculosis complex. Future studies ofM. africanum should include both phenotypic and genotypic analyses.

scholarly journals Norwegian Sheep Are an Important Reservoir for Human-Pathogenic Escherichia coli O26:H11

2012 ◽  
Vol 78 (12) ◽  
pp. 4083-4091 ◽  
Author(s):  
Lin T. Brandal ◽  
Camilla Sekse ◽  
Bjørn-Arne Lindstedt ◽  
Marianne Sunde ◽  
Inger Løbersli ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Virulence Gene ◽  
Variable Number ◽  
Pathogenic Potential ◽  
Content Type ◽  
E Coli ◽  
Pathogenic Escherichia Coli ◽  
Allele Type ◽  
Group A ◽  
Group B

ABSTRACTA previous national survey ofEscherichia coliin Norwegian sheep detectedeae-positive (eae+)E. coliO26:H11 isolates in 16.3% (80/491) of the flocks. The purpose of the present study was to evaluate the human-pathogenic potential of these ovine isolates by comparing them withE. coliO26 isolates from humans infected in Norway. All humanE. coliO26 isolates studied carried theeaegene and shared flagellar type H11. Two-thirds of the sheep flocks and 95.1% of the patients harbored isolates containingarcAallele type 2 andespKand were classified as enterohemorrhagicE. coli(EHEC) (stxpositive) or EHEC-like (stxnegative). These isolates were further divided into group A (EspK2 positive), associated withstx2-EDL933andstcEO103, and group B (EspK1 positive), associated withstx1a. Although thestxgenes were more frequently present in isolates from patients (46.3%) than in those from sheep flocks (5%), more than half of the ovine isolates in the EHEC/EHEC-like group had multiple-locus variable number of tandem repeat analysis (MLVA) profiles that were identical to those seen instx-positive human O26:H11 isolates. This indicates that EHEC-like ovine isolates may be able to acquirestx-carrying bacteriophages and thereby have the possibility to cause serious illness in humans. The remaining one-third of the sheep flocks and two of the patients had isolates fulfilling the criteria for atypical enteropathogenicE. coli(aEPEC):arcAallele type 1 andespKnegative (group C). The majority of these ovine isolates showed MLVA profiles not previously seen inE. coliO26:H11 isolates from humans. However, according to their virulence gene profile, the aEPEC ovine isolates should be considered potentially pathogenic for humans. In conclusion, sheep are an important reservoir of human-pathogenicE. coliO26:H11 isolates in Norway.

scholarly journals Muir-Torre Syndrome Presenting as Sebaceous Adenocarcinoma and Invasive MSH6-Positive Colorectal Adenocarcinoma

2016 ◽  
Vol 9 (1) ◽  
pp. 95-99 ◽  
Author(s):  
Sunil Tulpule ◽  
Hiyam Ibrahim ◽  
Mohamed Osman ◽  
Shoaib Zafar ◽  
Romana Kanta ◽  
...  
Keyword(s):  
Colorectal Adenocarcinoma ◽  
Surgical Intervention ◽  
Mismatch Repair Genes ◽  
Colorectal Carcinomas ◽  
Ascending Colon ◽  
Chemotherapy Treatment ◽  
Abdominal Ct ◽  
Internal Malignancy ◽  
Outpatient Chemotherapy ◽  
Repair Genes

Muir-Torre syndrome (MTS) is a rare genodermatosis, diagnosed by the presence of sebaceous neoplasms along with an internal malignancy, most commonly colorectal carcinomas. MTS is most commonly caused by microsatellite instabilities of the hMLH1 and hMSH2 mismatch repair genes, and is rarely caused by mutations of the hMSH6 gene. We describe the case of a 56-year-old male who presented with an enlarging mass on his back as well as hematochezia. The back mass was excised, and pathology confirmed microsatellite instability in MSH2 and MSH6. Abdominal CT and colonoscopy confirmed the presence of synchronous masses in the cecum, ascending colon, and the transverse colon. He refused any further workup or treatment, only to return 8 months later complaining of hematochezia and discomfort due to an enlarging mass protruding from the rectum. After consenting to surgical intervention, he agreed to outpatient chemotherapy treatment. The presence of sebaceous neoplasms should raise suspicion for the possibility of an associated internal malignancy.

Thymidylate synthase genotype specific dosing of capecitabine: Proof of concept phase I study.

2012 ◽  
Vol 30 (15_suppl) ◽  
pp. 2551-2551
Author(s):  
Ross A. Soo ◽  
Soo-Chin Lee ◽  
Wen-Lee Tan ◽  
Ling-Zhi Wang ◽  
Xn-Yii Lim ◽  
...  
Keyword(s):  
Phase I ◽  
Thymidylate Synthase ◽  
Turnaround Time ◽  
Dose Finding ◽  
Advanced Stage ◽  
Hand Foot Syndrome ◽  
Group A ◽  
Recommended Phase Ii Dose ◽  
Group B ◽  
Patient Enrolment

2551 Background: Thymidylate synthase (TYMS) is the target of fluoropyrimidines (FP). TYMS 3R3R is the predominant genotype in East Asian (EA) patients and is associated with increased TYMS expression, reduced FP related toxicity and relative FP resistance. Dose finding studies for FP were developed in Caucasians, a population that typically harbors TYMS 2R2R and 2R3R genotypes. We hypothesize the recommended phase II dose (RP2D) of capecitabine is higher in 3R3R and similar for 2R allele carriers compared to the FDA approved dose. Objectives 1) To determine the maximal tolerated dose (MTD) and RP2D of capecitabine in EA patients with advanced stage malignancy 2) To determine the safety and toxicity of this regimen and 3) To perform plasma pharmacokinetics (PK) of capecitabine and its metabolites. Methods: EA patients with advanced stage cancer were prospectively allocated into two cohorts: Group A (3R3R) and Group B (2R3R, 2R2R). In each cohort, dose escalation followed a standard phase I 3+3 design. Additional patients were treated at the R2P2 dose level (DL). Initial dose was 1250/m2 bd for 14 days q3w (DL 1) with 125 mg/m2 bd increments subsequently. Pharmacokinetics (PK) of capecitabine and its metabolites were performed using a LC-MS/MS method. Results: 23 patients (Group A=18; group B=5) received 94 cycles (median 2.5, range 1-8). Median age was 58 (range 34-74) years. Median turnaround time for TYMS genotyping was 1 day. In group A, grade 3-4 DLTs were seen in 3 patients: diarhoea, neutropenic fever, hand-foot syndrome, and mucositis. MTD was at DL 4 (1625mg/m2 bd) and the RP2D was 1500mg/m2 bd (DL 3). DL 3 was expanded to n=9. At DL 3, day 1 mean (± SD) capecitabine and 5FU Cmax was 12.3 ± 9.9 and 0.91 ± 0.73 µg/mL, respectively and AUC0 – t was 9.84 ± 5.53 and 1.21 ± 0.54 h*µg/mL, respectively. Compared with DL1, Cmax for capecitabine and 5FU was 2 and 2.02 fold higher and AUC 0-t was 1.49 and 1.59 fold higher at DL3. Accrual in group B was ceased at DL2 due to lack of patient enrolment; no DLT was seen. By ROC analysis, day 1 5FU AUC0 – t of 1.74 h*µg/mL predicted for DLT (p=0.022, sensitivity 100%, specificity 90%). Conclusions: In EA patients with TSER 3R3R, the RP2D was 1500 mg/m2 bd. The D1 5FU AUC0 – t at RP2D was 59% more than the FDA approved dose (DL1).

scholarly journals A Novel Nomenclature for Repeat Motifs in the Thymidylate Synthase Enhancer Region and Its Relevance for Pharmacogenetic Studies

2020 ◽  
Vol 10 (4) ◽  
pp. 181
Author(s):  
Dominic Schaerer ◽  
Tanja K. Froehlich ◽  
Seid Hamzic ◽  
Steven M. Offer ◽  
Robert B. Diasio ◽  
...  
Keyword(s):  
Adverse Events ◽  
Thymidylate Synthase ◽  
Binding Sites ◽  
Tandem Repeats ◽  
Variable Number ◽  
Gastrointestinal Toxicity ◽  
Genetic Associations ◽  
Upstream Stimulatory Factor ◽  
Enhancer Region ◽  
Stimulatory Factor

Inhibition of thymidylate synthase (TS) is the primary mode of action for 5-fluorouracil (5FU) chemotherapy. TS expression is modulated by a variable number of tandem repeats in the TS enhancer region (TSER) located upstream of the TS gene (TYMS). Variability in the TSER has been suggested to contribute to 5FU-induced adverse events. However, the precise genetic associations remain largely undefined due to high polymorphism and ambiguity in defining genotypes. To assess toxicity associations, we sequenced the TSER in 629 cancer patients treated with 5FU. Of the 13 alleles identified, few could be unambiguously named using current TSER-nomenclature. We devised a concise and unambiguous systematic naming approach for TSER-alleles that encompasses all known variants. After applying this comprehensive naming system to our data, we demonstrated that the number of upstream stimulatory factor (USF1-)binding sites in the TSER was significantly associated with gastrointestinal toxicity in 5FU treatment.

An ultrastructural study of sertoli cells in two geographically isolated populations of Aphanius dispar

1992 ◽  
Vol 50 (1) ◽  
pp. 548-549
Author(s):  
Taber A. Ba-Omar ◽  
Philip F. Prentis
Keyword(s):  
Ultrastructural Level ◽  
Uranyl Acetate ◽  
Freshwater Teleost ◽  
Isolated Populations ◽  
En Bloc ◽  
The North ◽  
Group A ◽  
Ultrathin Sections ◽  
Group B ◽  
Geographically Isolated

We have recently carried out a study of spermiogenic differentiation in two geographically isolated populations of Aphanius dispar (freshwater teleost), with a view to ascertaining variation at the ultrastructural level. The sampling areas were the Jebel Al Akhdar in the north (Group A) and the Dhofar region (Group B) in the south. Specimens from each group were collected, the testes removed, fixed in Karnovsky solution, post fixed in OsO, en bloc stained with uranyl acetate and then routinely processed to Agar 100 resin, semi and ultrathin sections were prepared for study.

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