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Biomedical subjects

Gregory J Tsongalis

Publications and source records attributed to Gregory J Tsongalis.

At least 19 recordsLinked to original sources
PubMed2007

Dietary calcium intake and renin angiotensin system polymorphisms alter the blood pressure response to aerobic exercise: a randomized control design.

BACKGROUND: Dietary calcium intake and the renin angiotensin system (RAS) regulate blood pressure (BP) by modulating calcium homeostasis. Despite similar BP regulatory effects, the influence of dietary calcium intake alone and combined with RAS polymorphisms on the BP response following acute aerobic exercise (i.e., postexercise hypotension) has not been studied. Thus, we examined the effect of dietary calcium intake and selected RAS polymorphisms on postexercise hypotension. METHODS: Subjects were men (n = 50, 43.8 +/- 1.3 yr) with high BP (145.3 +/- 1.5/85.9 +/- 1.1 mm Hg). They completed three experiments: non-exercise control and two cycle bouts at 40% and 60% of maximal oxygen consumption (VO2max). Subjects provided 3 d food records on five protocol-specific occasions. Dietary calcium intake was averaged and categorized as low (<880 mg/d = LowCa) or high (> or = 880 mg/d = HighCa). RAS polymorphisms (angiotensin converting enzyme insertion/deletion, ACE I/D; angiotensin II type 1 receptor, AT1R A/C) were analyzed with molecular methods. Genotypes were reduced from three to two: ACE II/ID and ACE DD; or AT1R AA and AT1R CC/AC. Repeated measure ANCOVA tested if BP differed among experiments, dietary calcium intake level and RAS polymorphisms. RESULTS: Systolic BP (SBP) decreased 6 mm Hg after 40% and 60% VO2max compared to non-exercise control for 10 h with LowCa (p < 0.01), but not with HighCa (p > or = 0.05). Under these conditions, diastolic BP (DBP) did not differ between dietary calcium intake levels (p > or = 0.05). With LowCa, SBP decreased after 60% VO2max versus non-exercise control for 10 h among ACE II/ID (6 mm Hg) and AT1R AA (8 mm Hg); and by 8 mm Hg after 40% VO2max among ACE DD and AT1R CC/CA (p < 0.01). With HighCa, SBP (8 mm Hg) and DBP (4 mm Hg) decreased after 60% VO2max compared to non-exercise control for 10 h (p < 0.05), but not after 40% VO2max (p > or = 0.05). CONCLUSION: SBP decreased after exercise compared to non-exercise control among men with low but not high dietary calcium intake. Dietary calcium intake interacted with the ACE I/D and AT1R A/C polymorphisms to further modulate postexercise hypotension. Interactions among dietary calcium intake, exercise intensity and RAS polymorphisms account for some of the variability in the BP response to exercise.

Journal Article↗
PubMed2006

The effect of apolipoprotein E genotype on serum lipoprotein particle response to exercise.

Exercise affects lipoprotein metabolism and apolipoprotein E (Apo E) genotype may alter changes in lipoprotein subclasses that occur with exercise. The present study examined the effects of Apo E genotype (APOE) on the response of lipoprotein subclass concentrations to long-term exercise. A prospective longitudinal study, conducted at seven centers, genetically screened 566 individuals to create three cohorts of healthy adults, equal for gender and the most common APOE variants: E2/3 (n = 35), E3/3 (n = 40), and E3/4 (n = 31). Subjects with body mass index (BMI) > or = 31 or evidence of dyslipidemia or metabolic disease were excluded. All subjects exercised aerobically at 75% of maximal heart rate for 40 min, four times weekly for 6 months. Fasting lipoprotein subpopulations were measured before and after exercise training using proton nuclear magnetic resonance spectroscopy. Serum lipids for the entire cohort did not change with exercise training, but the LDL subpopulation response varied by APOE. Small-sized LDL particles decreased only in the APOE3 homozygotes whereas medium-sized LDL particles increased only in this group. These changes were directionally different from the responses in the E2/3 and E3/4 subjects (p < 0.05). Neither exercise nor APOE variant affected overall LDL or HDL size or cholesterol concentration, but exercise decreased VLDL diameter by 3.5 nm (p < 0.001) attributable to decreases in large VLDL in each APOE group. In conclusion, APOE variants influence the serum LDL subpopulation response to exercise training in normolipidemic subjects. Subjects homozygous for APOE3 experienced the most beneficial lipid effects from exercise training.

Adolescent↗
PubMed2006

Molecular diagnostics: a historical perspective.

The rapid growth in molecular diagnostic testing, which has averaged between 10% and 20% per year for the past 5 years, is largely attributable to both breakthroughs in our basic understanding (i.e., the Human Genome Project) and in applied technology. In the past decade, molecular applications have moved from labor-intensive and manual to rapid and automated due to improvements in sample extraction, target amplification, and sensitive and specific detection schema. This review describes some of the more significant technological milestones of the past 10 years and, when tied to basic and applied research, how these have led to important clinical applications. The next decade promises even more exciting technologies and applications for the field of molecular laboratory medicine.

Clinical Laboratory Techniques↗
PubMed2006

RAAS polymorphisms alter the acute blood pressure response to aerobic exercise among men with hypertension.

Limited evidence suggests renin-angiotensin-aldosterone system (RAAS) polymorphisms alter the blood pressure (BP) response to aerobic exercise training. We examined if RAAS polymorphisms influenced postexercise hypotension in men with high normal to Stage 1 hypertension. Forty-seven men (44.2+/-1.4 years, 145.1+/-1.6/85.5+/-1.1 mmHg) randomly completed three experiments: seated rest (control) and two cycle exercise bouts at 40% (LITE) and 60% (MOD) of maximal oxygen consumption. Ambulating BP was measured for 14 h after each experiment. RAAS polymorphisms associated with hypertension (i.e. angiotensin converting I enzyme, ACE I/D; angiotensin II type 1 receptor, AT1R A/C; and intron 2 of aldosterone synthase, Int2 W/C) were analyzed using polymerase chain reaction and restriction enzyme digestion. Repeated measure ANOVA tested if BP differed between experimental conditions by RAAS genotypes. Compared to men with 0-2 variant alleles, men with > or =3 combined RAAS variant alleles had lower average systolic BP (SBP) (P=0.030) and lower average diastolic BP (DBP) (P=0.009) for 14 h only after LITE. In contrast, average BP was not different for MOD and control between RAAS variant allele groups over this time period (P> or =0.05). LITE reduced BP in men with > or =3 variant RAAS alleles for 14 h, whereas MOD had no influence on BP in these men. In order to optimally prescribe exercise for its BP lowering benefits in those with hypertension, additional knowledge of how genetic variation affects the BP response to exercise is needed.

Adult↗
PubMed2006

Negative urine opioid screening caused by rifampin-mediated induction of oxycodone hepatic metabolism.

INTRODUCTION: Oxycodone has become widely used in the clinic for the treatment of chronic pain. This reflects its favorable pharmacokinetics and side effect profiles. CASE REPORT: We report a 60-y-old man who had a clinically significant drug interaction between rifampin and oxycodone, resulting in 3 consecutive negative urine oxycodone screens in a 2-month period, suggesting non-adherence. A combination of urine opioid metabolite quantification by GC/MS and CYP genotyping confirmed that he was compliant with his oxycodone therapy. Determination of the complete oxycodone metabolite profile and the CYP3A4/5 and 2D6 genotype allowed the physician to be confident that the patient was compliant with the medication (and not diverting it) and to increase his oxycodone dose to optimize his pain control. CONCLUSION: This case demonstrates how the combination of analytical toxicology and pharmacogenetic analyses enhances a physician's ability to personalize drug therapy in patients with chronic pain syndromes.

Cytochrome P-450 CYP2D6↗
PubMed2006

Molecular mechanisms of human carcinogenesis.

Intensive research efforts during the last several decades have increased our understanding of carcinogenesis, and have identified a genetic basis for the multi-step process of cancer development. Tumors grow through a process of clonal expansion driven by mutation. Several forms of molecular alteration have been described in human cancers, and these can be generally classified as chromosomal abnormalities and nucleotide sequence abnormalities. Most cancer cells display a phenotype characterized by genomic hypermutability, suggesting that genomic instability may precede the acquisition of transforming mutations in critical target genes. Reduced to its essence, cancer is a disease of abnormal gene expression, and these genetic abnormalities contribute to cancer pathogenesis through inactivation of negative mediators of cell proliferation (including tumor suppressor genes) and activation of positive mediators of cell proliferation (including proto-oncogenes). In several human tumor systems, specific genetic alterations have been shown to correlate with well-defined histopathological stages of tumor development and progression. Although the significance of mutations to the etiological mechanisms of tumor development has been debated, a causal role for such genetic lesions is now commonly accepted for most human cancers. Thus, genetic lesions represent an integral part of the processes of neoplastic transformation, tumorigenesis, and tumor progression, and as such represent potentially valuable markers for cancer detection and staging.

Cell Transformation, Neoplastic↗
PubMed2006

Angiotensin-converting enzyme genotype and adherence to aerobic exercise training.

Angiotensin-converting enzyme (ACE) has two common genetic variants: the insertion (I) and deletion (D) forms. ACE levels are greater in subjects with the D allele, and several studies suggest superior endurance performance in subjects with the I allele. The authors recently reported the results of a 6-month exercise training protocol examining the effect of apolipoprotein E on the lipid response. The present report examines the relationship of ACE genotype and exercise adherence. DNA samples were available for 110 subjects: 14 I/I, 52 I/D, and 44 D/D. Baseline and change in maximal oxygen uptake, body mass index, skinfold thickness, and serum lipids did not differ by ACE genotype, but adherence to exercise training was higher in I carriers than in D homozygotes. These preliminary results suggest that ACE genotype affects exercise adherence and raises the possibility that superior endurance capacity in subjects with the I allele is related to a genetic propensity to adhere to an exercise regimen.

Adolescent↗
PubMed2006

Branched DNA technology in molecular diagnostics.

Viral quantification or viral load testing has become part of the routine management of patients infected with HIV-1 or hepatitis C virus (HCV). There are currently several molecular technologies that are available for use in the clinical laboratory setting. Of these, only the branched DNA (bDNA) assays are FDA-approved for HIV-1 and HCV viral load testing. This signal amplification technology is built on a series of hybridization reactions that are highly amenable to full automation and thus lessen the amount of labor required to perform this type of analysis. This article provides a historical perspective of bDNA and its clinical applications.

Acquired Immunodeficiency Syndrome↗
PubMed2006

BRCA1 and BRCA2 mutation screening using SmartCycler II high-resolution melt curve analysis.

CONTEXT: Real-time polymerase chain reaction technologies have replaced many of the more labor-intense methods in the molecular diagnostics laboratory. Similarly, melt curve analysis can provide a rapid means of mutation screening. OBJECTIVE: To determine if real-time polymerase chain reaction and melt curve analysis using the SmartCycler II could be used as a screening tool for 3 common mutations in BRCA1 and BRCA2. DESIGN: Real-time polymerase chain reaction amplification with SYBR Green I detection was performed on DNA from cell lines known to carry the 185delAG or 5382insC mutation in BRCA1 or the 6174delT mutation in BRCA2. The melting temperatures and the melt curves were analyzed for differences between wild-type DNA and cell lines that were heterozygous for each mutation. RESULTS: Significant differences were present in the melt curves for each of the mutations compared with those of the wild-type sequences. The melt curve for the 185delAG mutation showed a separate peak at a lower temperature, which represented the melting temperature of the heteroduplex. For the 6174delT mutation, the melt curve had a shoulder at a lower temperature, while the melt curve for the 5382insC mutation was shifted to the left and was broader than that for the wild-type sequences. CONCLUSIONS: High-resolution melt curve analysis is a quick, reliable method for identifying mutations due to small deletions or insertions. As a proof of principle, we used this assay to identify the 3 most common BRCA1 and BRCA2 mutations in the Ashkenazi Jewish population.

Cell Line, Tumor↗
PubMed2005

Clinical genotyping: the need for interrogation of single nucleotide polymorphisms and mutations in the clinical laboratory.

BACKGROUND: Detection of single nucleotide polymorphisms (SNPs) and gene mutations is becoming more routine to the clinical laboratory. METHODS: Completion of the Human Genome Project has led to new scientific knowledge of human disease processes that has revealed the most fundamental of abnormalities in nucleic acids while at the same time bringing some of the most sophisticated diagnostic tools to the clinical laboratory. In addition, public awareness (both lay persons and healthcare providers) and sensitivity to human genetics has increased tremendously. Together, this rapidly evolving science and increased public education has led to an increasing demand for genotypic testing. CONCLUSIONS: There are several clinical applications of human genotyping that are available using these newer technologies.

Base Sequence↗
PubMed2005

Apolipoprotein A1 genotype affects the change in high density lipoprotein cholesterol subfractions with exercise training.

High density lipoprotein cholesterol (HDL-C) is a primary risk factor for cardiovascular disease. Apolipoprotein A-1 (apoA1) is the major HDL-associated apolipoprotein. The -75G/A single nucleotide polymorphism (SNP) in the apolipoprotein A1 gene (APOA1) promoter has been reported to be associated with HDL-C concentrations as well as HDL-C response to dietary changes in polyunsaturated fat intake. We examined the effect of this APOA1 SNP on exercise-induced changes in HDL subfraction distribution. From a cohort of healthy normolipidemic adults who volunteered for 6 months of supervised aerobic exercise, 75 subjects were genotyped for the -75G/A SNP. Of these, 53 subjects were G homozygotes (G/G) and 22 were A carriers (A/G and A/A). HDL subfractions were measured by nuclear magnetic resonance (NMR) spectroscopy by adding categories HDL-C 1+2 for the small subfraction, and HDL-C 3+4+5 for the large. The change in total HDL-C after exercise was 0.8+/-7.2 mg/dL (+1.7%), and was not statistically significant. HDL subfraction amounts also did not significantly change with exercise training in the total cohort or in G homozygotes or A carriers. The amount of the large HDL subfraction increased in the G homozygotes and decreased in the A carriers (mean+/-S.E.M., 1.8+/-6.6 mg/dL versus -6.1+/-2.3 mg/dL, p<0.0005). In contrast, the amount of the small HDL subfraction decreased in G homozygotes and increased in A carriers (-1.3+/-6.6 mg/dL versus 4.7+/-1.2 mg/dL, p<0.005). These results show that genetic variation at the APOA1 gene promoter is associated with HDL subfraction redistribution resulting from exercise training.

Adolescent↗
PubMed2005

Parameters involved in the conversion of real-time PCR assays from the ABI prism 7700 to the Cepheid SmartCycler II.

OBJECTIVE: We examined several critical parameters that must be optimized when converting between the ABI Prism 7700 real-time PCR platform and the Cepheid SmartCycler II while using the same primer and probe sequences. DESIGN AND METHODS: A lyophilized master mix, MgCl(2) concentration, PCR cycling conditions, and ramp times were evaluated. RESULTS: Optimization of each parameter, including use of the OmniMix HS-lyophilized beads, 6 mM MgCl(2) concentration, changes in PCR cycling parameters, and increased ramp time were necessary to convert this real time PCR assay to a new platform. CONCLUSION: We conclude that careful consideration of several analytical parameters can result in a smooth transition of assays between real time PCR platforms.

Indicators and Reagents↗
PubMed2005

Prevalence of the Factor V G1691A and the Factor II/prothrombin G20210A gene polymorphisms among Tamilians.

We have investigated the prevalence of the Factor II G20210A and Factor V G1691A single nucleotide polymorphisms (SNPs) in a South Indian-Tamil Nadu population. The SNP genotyping was performed using a polymerase chain reaction (PCR)/restriction fragment length polymorphism analysis and by a recently FDA-approved LightCycler real-time PCR assay. Of 72 samples that were genotyped, 4 (5.5%) patients were heterozygous for the Factor V SNP and no homozygous mutant patients were identified. None of the patients were shown to be either heterozygous or homozygous mutant for the Factor II SNP. All samples showed 100% concordance between the PCR/RFLP assay and the LightCycler assay. While this study identified the prevalence of the Factor V SNP to be similar to that of other reported populations, the absence of the Factor II allele is consistent with reports in more isolated populations. In addition, the results of this study do not support a role for these SNPs in acute myocardial infarction in the Tamilian population.

DNA Mutational Analysis↗
PubMed2005

Real-time polymerase chain reaction and laser capture microdissection for the diagnosis of BK virus infection in renal allografts.

We used real-time polymerase chain reaction (PCR) technology to detect BK virus (BKV) in H and E-stained kidney biopsy sections, using laser capture microdissection. Renal allograft biopsy specimens from 4 patients with the histopathologic diagnosis of BKV-associated nephropathy (BKVAN; group 1) and 3 patients suspected to have BKVAN but without diagnostic histologic features (group 2) were retrieved. Diagnostic inclusion-bearing cells were microdissected by laser capture microscopy from group 1. Renal tubular epithelial cells were microdissected randomly in group 2. DNA was extracted and real-time amplification performed using primers targeting the large "T" and small "t" regions of the BKV and JC virus genomes. Tubular epithelial cells from a case without evidence of BKV infection were used as negative controls in a similar reaction. BKV presence was demonstrated only in epithelial cells containing typical viral inclusions. Group 2 and negative control samples were confirmed as negative for BKVAN. Real-time PCR technology can be used to detect BKV in H and E-stained, paraffin-embedded tissue sections. This technique detected BKV in tubular epithelial cells of renal allografts. To our knowledge, this is the first report of detecting BKV in laser capture microdissected renal biopsy specimens using real-time PCR.

BK Virus↗
PubMed2005

Primary carcinoid tumor of the common hepatic duct: A rare case with immunohistochemical and molecular findings.

We report immunohistochemical (IHC) and molecular findings in a rare case of a carcinoid tumor of the extrahepatic bile ducts in a 33-year-old woman, who presented with a 3.9x2.8x2.6 cm mass within the right and common hepatic ducts. She underwent surgery and a carcinoid tumor was identified. This lesion is of interest because in addition to the morphological and cytological features of a typical carcinoid, it demonstrated a distinct pleomorphic area immunoreactive for gastrin. By molecular analysis, loss of heterozygosity (LOH) with opposite allelic patterns between the gastrin-positive and gastrin-negative areas of the tumor was identified. The molecular studies for LOH along with the morphology and IHC profiling suggest that this second population of gastrin-positive carcinoid cells may represent a new clone within the carcinoid tumor with differentiation toward gastrin production or may represent the next step in the carcinogenic process with a gradual emergence of a more aggressive clone.

Adult↗