PubMed Health⌕ Search

Biomedical subjects

Youvraj R Sohni

Publications and source records attributed to Youvraj R Sohni.

6 recordsLinked to original sources
PubMed2004

Endothelial nitric oxide synthase gene polymorphisms predict susceptibility to aneurysmal subarachnoid hemorrhage and cerebral vasospasm.

Rupture of an intracranial aneurysm (subarachnoid hemorrhage) is a potentially devastating condition frequently complicated by delayed cerebral ischemia from sustained contraction of intracranial arteries (cerebral vasospasm). There is mounting evidence linking the formation of intracranial aneurysms and the pathogenesis of post-subarachnoid hemorrhage vasospasm to aberrant bioavailability and action of the vasodilator molecule nitric oxide generated by isoforms of nitric oxide synthase. In humans, the gene encoding the endothelial isoform of nitric oxide synthase (eNOS) is known to be polymorphic, with certain polymorphisms associated with increased cardiovascular disease susceptibility. In this prospective clinical study involving 141 participants, we used gene microarray technology to demonstrate that the eNOS gene intron-4 27-base pair variable number tandem repeat polymorphism (eNOS 27 VNTR) predicts susceptibility to intracranial aneurysm rupture, while the eNOS gene promoter T-786C single nucleotide polymorphism (eNOS T-786C SNP) predicts susceptibility to post-subarachnoid hemorrhage vasospasm. We believe that genetic information such as this, which can be obtained expeditiously at the time of diagnosis, may be used as a helpful adjunct to other clinical information aimed at predicting and favorably modifying the clinical course of persons with intracranial aneurysms.

Adult↗
PubMed2003

Endothelial nitric oxide synthase T-786C single nucleotide polymorphism: a putative genetic marker differentiating small versus large ruptured intracranial aneurysms.

BACKGROUND AND PURPOSE: Anecdotal evidence exists for at least 2 subpopulations of intracranial saccular aneurysms, namely, those that may form rapidly and rupture when small versus those that enlarge slowly and may rupture particularly when > or =10 mm in diameter. We sought to determine whether the endothelial nitric oxide synthase (eNOS) T-786C single nucleotide polymorphism (SNP), implicated in cardiovascular disease susceptibility, could facilitate differentiation between small (< or =5 mm) versus large (> or =10 mm) ruptured aneurysms. METHODS: In accordance with institutional guidelines, clinical data were recorded prospectively and genomic DNA was isolated from blood samples obtained from 52 aneurysmal subarachnoid hemorrhage (SAH) patients (cases) and 90 randomly selected controls. Samples were assayed for eNOS gene promoter T-786C SNP with the use of gene microarray technology. Statistical analyses included multiple logistic regression. RESULTS: Although there was no difference in genotype distributions between cases and controls, all 13 patients with large aneurysms were (T/C) heterozygous for the polymorphism, while 9 of 22 patients (41%) with small aneurysms were (T/T or C/C) homozygous (P=0.01). The mean (+/-SD) ruptured aneurysm diameter among all heterozygotes (8.5+/-5.2 mm) was significantly greater than that for C/C (6.0+/-2.3 mm) or T/T (4.7+/-1.8 mm) homozygotes (P=0.04). With the use of multivariate analysis, heterozygosity remained significantly associated with aneurysm size > or =10 mm (P=0.03). CONCLUSIONS: The eNOS T-786C SNP distinguishes genetically between small and large ruptured aneurysms. Although not predictive of SAH in the population at large, our data suggest that among persons with known intracranial aneurysms, eNOS T-786C genotype may be a factor influencing the size at which an aneurysm ruptures, a finding that should be taken into consideration along with other anatomic features of the aneurysm.

Age Distribution↗
PubMed2003

Microfluidic chip-based method for genotyping microsatellites, VNTRs and insertion/deletion polymorphisms.

We have developed a method to genotype variable number of tandem repeats (VNTRs) and insertion/deletion polymorphisms using an integrated microfluidic chip-based system. We used this method to analyze a) a highly polymorphic pentanucleotide repeat (CCTTT)(n) locus within the 5'-putative promoter region of the human inducible nitric oxide synthase gene (iNOS5) which is associated with diabetic complications and infectious diseases; b) a bi-allelic 27 bp VNTR region within intron 4 of endothelial nitric oxide gene (eNOS27) which is associated with hypertension in type 2 diabetes patients with coronary heart disease and excess risk of advanced diabetic nephropathy in type 1 diabetes patients and c) an insertion/deletion polymorphism within the gene encoding angiotensin-converting enzyme (ACE/ID) which is associated with cardiovascular pathology and nitric oxide activity, and is in strong linkage disequilibrium with functional variants. Following amplifications, samples were mixed with gel-dye and markers and loaded into commercially available microfluidic chips designed for DNA sizing applications. In the study (N = 230), 95 (41%) of the DNA samples were homozygous and 135 (59%) were heterozygous for the iNOS5 repeats. For eNOS27, 173 (75%) of the genotyped DNA samples were homozygous for the larger 4b allele and the remaining 57 samples (25%) were heterozygous (4b/4a). No DNA samples were homozygous for the shorter 4a allele with four 27 bp repeats. In case of ACE/ID, 47 (20%) of the DNA samples were homozygous for the insertion, 65 (28%) were homozygous for the deletion and the remaining 118 (51%) were heterozygous. The results obtained were verified by analyzing random amplicons using bi-directional sequencing and GeneScan 3.0 analyses with 100% concordance being observed. Using the microfluidic chip-based method, separation and DNA sizing and genotyping are rapidly accomplished. The DNA fragments are resolved clearly and the system allows quantitation. Finally, the microfluidic chip-based method may be used for both large- and small-scale genotyping studies.

Alleles↗
PubMed2003

TAP1, TAP2, and HLA-DR2 alleles are predictors of cervical cancer risk.

OBJECTIVE: The likelihood of developing cervical cancer has been shown to be increased in persons with certain HLA alleles. We evaluated immune response genes in the HLA region of chromosome 6 to see if individual or interactive associations with cervical cancer risk could be identified. METHODS: Tissue was obtained from 127 women undergoing surgical treatment for cervical cancer. Blood samples were obtained from 175 control subjects. A combination of polymerase chain reaction (PCR), sequence-specific PCR, and DNA sequencing was used to evaluate polymorphic alleles, including HLA class I B7, TNF alpha, HLA class II DR2, TAP1, and TAP2 genes. Fisher's exact test and logistic regression modeling were used for statistical analysis. RESULTS: A significantly greater proportion of the patients with cervical cancer were found to have the HLA class II DR2 1501 allele (P = 0.023) and the TAP2 A/B heterozygous pattern of alleles (P = 0.0006) than were women without cervical cancer. A proportion of patients with cervical cancer significantly smaller than that of the control women had a polymorphism at the -238 position of the TNF promoter and the TAP1 C/C homozygous pattern of alleles. With logistic modeling, the markers that showed consistent association with the occurrence of cervical cancer were TAP2 A/B, HLA-DR2 1501, and TAP1 C/C. CONCLUSIONS: We demonstrated a significant association between immune response genes and the risk of cervical cancer. Our data create a compelling argument for a gene or a cluster of genes in the HLA region of chromosome 6 that regulates host immune responses to human papillomavirus infection in a manner that results in inherited susceptibility or resistance to the transforming properties of oncogenic papillomaviruses.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2003

Microarray and microfluidic methodology for genotyping cytokine gene polymorphisms.

Cytokine genetic polymorphisms are the subject of disease-association studies that require large-scale human genotyping. Polymerase chain reaction based custom microarrays and microfluidics systems were used to develop genotyping assays for following cytokine polymorphisms: tumor necrosis factor-alpha G-308A, interleukin-4 (IL-4) C-589T, interferon-gamma (CA)n repeats, IL-1RN 86-bp variable number of tandem repeats (VNTR), and CCR5 32-bp indel. For G-308A, 70.9% of DNA samples assayed were homozygous for wild type, 25.5% were heterozygous, and none were homozygous for variant allele. For C-589T, 35.5% of DNA samples were homozygous for wild type, 38% were heterozygous, and 22% were homozygous for variant. For IL-1RN VNTR, 71% of DNA samples were homozygous and the remainder were heterozygous. For CCR5, 96.4% of amplicons were homozygous for wild type, and 3.6% were heterozygous containing deletion. For IFN-gamma (CA)n repeats, 35.6% had 2,2 alleles, 42.2% had 2,3 alleles, and 11% had 3,3 alleles with alleles 1 through 5 corresponding to 11 through 15 repeats, respectively. There was good concordance between the results we obtained and current "gold-standard" methodologies for analyzing single nucleotide polymorphisms and size polymorphisms. Electronic DNA concentration with high stringency predisposes microarray technology to hybridization fidelity and accuracy, and microfluidics systems outperform conventional methodologies for size polymorphisms. Comprehensive genotyping can be achieved for clinical epidemiologic studies on cytokine gene polymorphisms using this approach.

Cytokines↗