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At least 163 records · Page 9Linked to original sources
PubMed2002

Renin-angiotensin system genetic polymorphisms and cerebral white matter lesions in essential hypertension.

It has been reported that both the DD genotype of the angiotensin converting enzyme (ACE) gene and the presence of cerebral white matter lesions (WML) may represent risk factors for the development of stroke. The present study investigates a possible association between 3 different genetic polymorphisms of the renin-angiotensin system and the presence of WML in 60 never-treated essential hypertensive patients (36 men, 24 women), aged 50 to 60 years, without clinical evidence of target organ damage. All patients underwent brain magnetic resonance imaging to establish the presence or absence of WML. The insertion/deletion (I/D) ACE gene, the M235T angiotensinogen (AGT) gene, and the A1166C angiotensin II type 1 receptor gene polymorphisms were determined by standard polymerase chain reaction. Twenty-five hypertensive patients (41.6%) were found to have WML on brain magnetic resonance imaging. No significant association between the M235T angiotensinogen or A1166C angiotensin II type 1 receptor genotypes and the presence of WML was found. However, the frequency of the DD genotype in patients with WML (64%) was significantly higher than that observed in patients without WML (28.6%; P=0.022). The DD genotype odds ratio for the presence of WML was 4.44 (95% confidence interval: 1.48 to 13.3). Likewise, the proportion of the D allele in patients with WML (74%) was significantly higher (P=0.014) than that observed in patients without WML (51.4%). We conclude that the presence of the DD genotype and/or the D allele of the ACE gene may be a predisposing factor for developing WML in essential hypertensive patients. However, because of the small sample size, these results require confirmation in a larger study.

Aged↗
PubMed2000

Oral microbial communities: biofilms, interactions, and genetic systems.

Oral microbial-plaque communities are biofilms composed of numerous genetically distinct types of bacteria that live in close juxtaposition on host surfaces. These bacteria communicate through physical interactions called coaggregation and coadhesion, as well as other physiological and metabolic interactions. Streptococci and actinomyces are the major initial colonizers of the tooth surface, and the interactions between them and their substrata help establish the early biofilm community. Fusobacteria play a central role as physical bridges that mediate coaggregation of cells and as physiological bridges that promote anaerobic microenvironments which protect coaggregating strict anaerobes in an aerobic atmosphere. New technologies for investigating bacterial populations with 16S rDNA probes have uncovered previously uncultured bacteria and have offered an approach to in situ examination of the spatial arrangement of the participant cells in oral-plaque biofilms. Flow cells with saliva-coated surfaces are particularly useful for studies of biofilm formation and observation. The predicted sequential nature of colonization of the tooth surface by members of different genera can be investigated by using these new technologies and imaging the cells in situ with confocal scanning laser microscopy. Members of at least seven genera now can be subjected to genetic studies owing to the discovery of gene-transfer systems in these genera. Identification of contact-inducible genes in streptococci offers an avenue to explore bacterial responses to their environment and leads the way toward understanding communication among inhabitants of a multispecies biofilm.

Bacteria↗
PubMed2000

Renin-angiotensin system genetic polymorphisms and salt sensitivity in essential hypertension.

We evaluated the association between salt-sensitive hypertension and 3 different genetic polymorphisms of the renin-angiotensin system. Fifty patients with essential hypertension were classified as salt sensitive or salt resistant, depending on the presence or absence of a significant increase (P<0.05) in 24-hour ambulatory mean blood pressure (BP) after high salt intake. The insertion/deletion (I/D) angiotensin-converting enzyme (ACE) gene, the M235T angiotensinogen (AGT) gene, and the A1166C angiotensin II type 1 (AT1) receptor gene polymorphisms were determined with the use of standard polymerase chain reaction methods. Twenty-four (48%) patients with significantly increased (P<0.05) 24-hour mean BP with high salt intake (from 107.3+/-9.4 to 114.8+/-10.6 mm Hg) were classified as salt sensitive. In the remaining 26 patients (52%), high salt intake did not significantly modify 24-hour mean BP (from 107.6+/-10 to 107. 8+/-9 mm Hg), and they were classified as having salt-resistant hypertension. We did not find any significant association between either M235T AGT or A1166C AT1 receptor genotypes and the BP response to high salt intake. However, patients with essential hypertension homozygous for the insertion allele of the ACE gene (II) had a significantly higher BP increase with high salt intake (9. 8+/-8.1 mm Hg for systolic BP and 5.2+/-4.2 mm Hg for diastolic BP) than that observed in patients homozygous for the deletion allele (DD) (1.2+/-5.9 mm Hg for systolic BP; P=0.0118 and -0.2+/-4.2 mm Hg for diastolic BP; P=0.0274). Heterozygous patients (ID) exhibited an intermediate response. The prevalence of salt-sensitive hypertension also was significantly higher (P=0.012) in II (67%) and DI patients (62%) compared with DD hypertensives (19%). We conclude that a significant association exists between the I/D polymorphism of the ACE gene and salt-sensitive hypertension. Patients with II and DI genotypes have significantly higher prevalence of salt sensitivity than DD hypertensives.

Adult↗
PubMed1985

Mapping genetic systems by the supratype method.

Kinship mapping and population supratypes provide information on order and relative genetic position of loci within a system too small to map by recombination. These methods are compared for the RH, beta-globin, HLA, and GM systems, where recombination between loci is estimated as 0.0002-0.0069. Supratype analysis does not appreciably improve kinship mapping. Mean recombination within systems appears to be 10(-4) morgans/kb, an order of magnitude greater than the average for the whole genome. Possible implications of this discrepancy are discussed.

Chromosome Mapping↗
PubMed1999

Cytochrome P450 enzyme system: genetic polymorphisms and impact on clinical pharmacology.

The cytochrome P450 (CYP) enzyme system is involved in the metabolism and elimination of numerous widely used drugs. The capacity of this system varies from one person to another, leading to variable drug excretion rates and intersubject differences in the final serum drug concentrations. For this reason, therapeutic response and side-effects vary widely between patients treated with the same dose of drug. The intersubject variability in metabolic rate is largely determined by genetic factors. Some CYP enzymes, including CYP2D6 and CYP2C19, are genetically polymorphic. Several mutant alleles have been described, Environmental factors such as smoking, diet and co-administration of medications might also influence the CYP enzyme activity. By the use of genotyping or phenotyping methods every individual can be classified as either a poor, an intermediate, an extensive or an ultrarapid metabolizer. If this could be performed prior to drug therapy, the knowledge could be applied to drug selection and dose adjustment in order to reach therapeutic serum drug levels.

Cytochrome P-450 Enzyme System↗
PubMed1991

Inter-alpha-trypsin inhibitor (ITI): a useful genetic system in paternity testing. Evidence for polymorphic occurrence of ITI*3 and existence of a new allele, ITI*4.

The genetic polymorphism of human inter-alpha-trypsin inhibitor (ITI) has been investigated in sialidase-treated samples by isoelectric focusing on polyacrylamide gels with a pH range 3.5-9.5 followed by passive blotting with enzyme immunoassay. In 400 blood donors from western Japan, 8 simplified band patterns were observed, 6 of which could be explained by the previously described 3 polymorphic alleles, ITI*1, ITI*2, and ITI*3. The others were products of a new and rare fourth allele designated ITI*4, whose expression is also consistent with autosomal codominant inheritance. The frequency of these alleles was 0.440, 0.526, 0.030 and 0.004, respectively. The theoretical exclusion rate for putative fathers in paternity cases was calculated to be 0.228. The ITI system is a useful genetic marker for forensic hemogenetics in Japanese and in Europeans.

Alleles↗
PubMed2003

[Structural and functional variability of genetic systems for catabolizing polycyclic aromatic hydrocarbons in Pseudomonas putida strains].

The genetic control of naphthalene, phenanthrene, and anthracene biodegradation was studied in three Pseudomonas putida strains isolated from coal tar- and oil-contaminated soils. These strains isolated from different geographical locations contained similar catabolic plasmids controlling the first steps of naphthalene conversion to salicylate (the nah1 operon), functionally inoperative salicylate hydroxylase genes, and genes of the metha-pathway of catechol degradation (the nah2 operon). Salicylate oxidation in these strains is determined by genes located in trans-position relative to the nah1 operon: in strains BS202 and BS3701, they are located on the chromosome, and in the strain BS3790, on the second plasmid.

Base Sequence↗
PubMed2004

The renin-angiotensin system genetic polymorphisms and rheumatic mitral valve disease.

BACKGROUND AND AIM OF THE STUDY: Angiotensin-converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism, angiotensinogen (AGT) gene polymorphism and angiotensin II type 1 receptor (AT1R) polymorphism in relation to rheumatic mitral valve disease were examined in a case-control study to investigate possible relationships between these gene polymorphisms and rheumatic mitral valve disease in patients undergoing mitral valve replacement (MVR). METHODS: A total of 50 patients with rheumatic mitral valve disease and undergoing MVR was compared with 50 normal, and age- and sex-matched control subjects. ACE I/D, AGT gene M235T and AT1R-adenine/cytosine 1166 (A1166C) genotype polymorphisms were identified by polymerase chain reaction (PCR) -based restriction analysis. RESULTS: ACE I/D polymorphism differed significantly between the groups. The control group mostly represented the heterozygote ID allele (74%), while the MVR group showed frequencies of 60% for the homozygote DD and II alleles. MM homozygote frequency was significantly greater in controls, but TT homozygote frequency was significantly greater in the MVR group. AT1R-A1166C genotype polymorphism also differed significantly between groups; the MVR group had 73.7% of the AC heterozygote allele, while controls had 64.4% of the AA and 66.7% of the CC homozygote alleles. CONCLUSION: These results provided evidence of an association between ACE I/D polymorphism, M235T polymorphism and AT1R-A1166C genotype polymorphism and rheumatic mitral valve disease.

Adult↗
PubMed1976

[2 genetic systems of serum amylase in the Kholmogor breed of cattle].

All the genetic types of amylase I (AmI) and amylase II (AmII) known for the species Bos taurus are encountered in the Kholmogorskaya breed of cattle. Besides the two alleles, AmIB and AmIC found in all the other European breeds of cattle the locus in the Kholmogorskaya breed also includes a rare allele AmI-A hitherto considered to be characteristic only of zebu-like cattle. The frequencies of the alleles AmI-A, AmI-B and AmI-C in the Kholmogorskaya breed proved to be 0.014, 0.392 and 0.594 respectively (n = 1098). Of the two co-dominant alleles, AmII-A and AmII-B controlling the synthesis of the isozymes of the second amylase system the first is rare, occurring with the frequency of 0.131 (n = 245). The earlier assumption of Mazumder and Spooner, that there is no linkage between the genes of the loci AmI and AmII is corroborated. The breeds assigned to the Bos taurus brachyceros type have a lower frequencies of the AmI-C allele as compared to other breeds the origin of which is associated with the subspecies B. t. primigenius.

Alleles↗
PubMed2000

Genetic systems for analyzing protein-protein interactions in bacteria.

Analysis of protein-protein interactions has been revolutionized by the yeast two-hybrid system introduced by Fields and coworkers. In recent years, similar genetic assays have been developed in bacteria. We describe here several of these systems and highlight some potential applications of these technologies.

Bacterial Proteins↗
PubMed1984

Genetic system of Schwanniomyces alluvius determined by diad analysis of fusion products.

The genetics of Schwanniomyces alluvius, a yeast that secretes alpha-amylase, were investigated. No mating types have been detected in this haploid organism. Hybrids were produced by protoplast fusion, and these were subjected to diad analysis by using two-spored asci. Results showed that the diploidy introduced by cell fusion persists through successive spore generations. It was concluded that in this organism, sporulation is preceded by the fusion of mitotic products, regardless of the ploidy of the latter. Routine procedures for constructing novel strains would, no doubt, be hampered by this failure of the sporulation process to restore haploidy. Nevertheless, chromosomal instability of hybrids, as indicated both by heterogeneity of fusion products and by a high frequency of morbidity among their segregants, may permit the use of classical genetic techniques for strain construction.

Ascomycota↗
PubMed1974

Correlations in multi-locus genetic systems: a mathematical model.

A spin model with parallels to a multi-locus genetic model is presented which makes it possible to calculate the correlation between allelic states at any two loci in a population at equilibrium. The main features are: (1) The decay of correlation with distance may be expressed essentially as a linear combination of two exponentials, one of which dominates when the two loci are sufficiently far apart. (2) The correlation between two loci a specified distance apart is increased as the number of loci in the entire system increases. The results are compared with those of other theoretical models and discussed in the light of available experimental data. Possible ways of generalizing the model are outlined. However, additional experimental data is clearly needed to indicate the genetic relevance of work of this nature.

Alleles↗
PubMed2000

A yeast-based genetic system for functional analysis of viral mRNA capping enzymes.

Virus-encoded mRNA capping enzymes are attractive targets for antiviral therapy, but functional studies have been limited by the lack of genetically tractable in vivo systems that focus exclusively on the RNA-processing activities of the viral proteins. Here we have developed such a system by engineering a viral capping enzyme-vaccinia virus D1(1-545)p, an RNA triphosphatase and RNA guanylyltransferase-to function in the budding yeast Saccharomyces cerevisiae in lieu of the endogenous fungal triphosphatase (Cet1p) and guanylyltransferase (Ceg1p). This was accomplished by fusion of D1(1-545)p to the C-terminal guanylyltransferase domain of mammalian capping enzyme, Mce1(211-597)p, which serves as a vehicle to target the viral capping enzyme to the RNA polymerase II elongation complex. An inactivating mutation (K294A) of the mammalian guanylyltransferase active site in the fusion protein had no impact on genetic complementation of cet1Deltaceg1Delta cells, thus proving that (i) the viral guanylyltransferase was active in vivo and (ii) the mammalian domain can serve purely as a chaperone to direct other proteins to the transcription complex. Alanine scanning had identified five amino acids of vaccinia virus capping enzyme-Glu37, Glu39, Arg77, Glu192, and Glu194-that are essential for gamma phosphate cleavage in vitro. Here we show that the introduction of mutation E37A, R77A, or E192A into the fusion protein abrogates RNA triphosphatase function in vivo. The essential residues are located within three motifs that define a family of viral and fungal metal-dependent phosphohydrolases with a distinctive capacity to hydrolyze nucleoside triphosphates to nucleoside diphosphates in the presence of manganese or cobalt. The acidic residues Glu37, Glu39, and Glu192 likely comprise the metal-binding site of vaccinia virus triphosphatase, insofar as their replacement by glutamine abolishes the RNA triphosphatase and ATPase activities.

Acid Anhydride Hydrolases↗
PubMed1991

Assignment of the Auberger red cell antigen polymorphism to the Lutheran blood group system: genetic justification.

Family studies have provided the final piece of evidence for the assignment of Auberger to the Lutheran blood group system. Lods derived from combined paternal and maternal meioses (zeta = 10.83 at theta = 0.00) strongly support the contention that a single gene controls the expression of both Au and LU antigens. Consequently, the International Society of Blood Transfusion Working Party on Terminology has designated Aua and Aub as LU18 and LU19, respectively.

Antigens↗