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At least 919 records · Page 51Linked to original sources
PubMed1977

Correlations of incidence rates for selected cancers in the nine areas of the Third National Cancer Survey.

Incidence date from the Third National Cancer Survey were used to study geographic variation in the occurrence of nine common cancers of nonsexual sites and five sexual sites. It was hypothesized that cancers which varied together across the nine survey communities might have common etiologic factors. The variation was measured by a series of rank and product-moment correlation coefficients in order to summarize the association between pairs of cancers in white males and in white females. The most notable findings were the high correlations between the incidence rates for the three gastrointestinal sites (stomach, colon, and rectum) and bladder cancer in both men and women and the high correlation between three female sexual sites (breast, corpus, and ovary). These two clusters are also correlated with one another. A number of other substantial correlations between pairs of cancers were observed and discussed. These associations suggest possible common etiologic agents, despite the fact that the individual secular trends for some of these cancers differ.

Breast Neoplasms↗
PubMed1994

Noninvasive imaging of the biliary tree before or after laparoscopic cholecystectomy: use of three-dimensional spiral CT cholangiography.

OBJECTIVE: The purpose of this study was to determine the feasibility of using three-dimensional spiral CT after IV administration of a cholangiographic agent for noninvasive detection of anatomic variations of the bile ducts and common bile duct stones before or after laparoscopic cholecystectomy. SUBJECTS AND METHODS: Three-dimensional spiral CT cholangiography was performed before laparoscopic cholecystectomy in 24 patients and after surgery in two patients who had recurrent symptoms. After slow infusion of 250 ml of iodipamide, spiral CT was performed. Three-dimensional images of the bile ducts and a secondary reformation through the long axis of the common bile duct were obtained. Visualization of the biliary tract was evaluated by two observers. Detection of anatomic variations and common bile duct stones was assessed in 19 patients for whom a gold standard (operative or retrograde cholangiogram) was available. RESULTS: In all 26 patients, the common bile duct and the confluence of the hepatic ducts were seen on three-dimensional spiral CT cholangiograms, and in 21 patients second- or higher-order branches were also seen. Seven patients had anatomic variations and two had common bile duct stones. These anomalies were proved by operative cholangiography in each case, except for a low junction of the cystic duct and a common bile duct stone, which were shown by retrograde cholangiography. Six of the seven anatomic variations were adequately detected with spiral CT cholangiography, as were the two cases of common bile duct stones. CONCLUSION: Three-dimensional spiral CT cholangiography is a feasible method for noninvasive detection of biliary anatomic variations and common bile duct stones before or after laparoscopic cholecystectomy.

Bile Ducts↗
PubMed2001

Go!Poly: A gene-oriented polymorphism database.

Human genome polymorphisms play a key role in defining the molecular basis of phenotypic differences between individuals in aspects such as disease susceptibility and drug responses. The database requirements for supporting the study of human genetic variation have been well recognized. In order to meet these needs, several generalized databases have been built. However, it is still hard for users to find gene-related variation data from these huge and sophisticated databases. In its role as a gene-oriented directory of polymorphism data, Go!Poly (Gene Oriented Polymorphism Database; http://61.139.84.5/gopoly/) utilizes two new highly curated and non-redundant resources, LocusLink (http://www.ncbi.nlm.nih.gov/LocusLink/) and RefSeq (http://www.ncbi.nlm.nih.gov/LocusLink/refseq.html), as the standard for identifying and positioning nucleotide variations. As a generalized polymorphism database, Go!Poly extracts human gene-linked sequence variations of all common types (SNP, insertion-deletion, simple tandem repeat, and complex nucleotides variations) from various public resources including scientific journals and internet resources, such as HGBASE (http://hgbase.cgr.ki.se) and dbSNP (http://www.ncbi.nlm.nih.gov/SNP/). The polymorphism data are then categorized into different gene loci, and the reference sequences given by LocusLink are used as positioning references. Through close integration with LocusLink, Go!Poly also provides facilitated connections among sequence data, gene name, and related biological information. This feature also makes Go!Poly easy to search and navigate. Future automated annotations and internal consistency checking may also benefit from this. Extensive efforts are being taken to make the polymorphism information generated by the Chinese scientific community available from this resource.

China↗
PubMed1981

Numerical analysis of the human fetal heart rate: modulation by breathing and movement.

Signal averaging has been used to identify the modulation of fetal heart periods (pulse intervals) by body movements and breathing, identified by a real-time ultrasound scan in normal pregnancies of 37 to 39 weeks. Accelerations were associated with fetal movements and were accompanied by arrest of fetal breathing and a decrease in beat-to-beat variation. They were commonly succeeded by decelerations, with an increase in beat-to-beat variation, within 15 to 20 seconds. In the absence of gross accelerations or decelerations, fetal breathing was associated with a high-frequency modulation of heart periods, measureable as a small increase in beat-to-beat variation. There was clustering of this characteristic pattern around and within fetal breathing episodes, which suggests that it may be a more sensitive index of breathing than visual identification with ultrasound. The conclusions are: (1) the grosser episodic changes in fetal heart rate are associated with the regular repetition of a pattern of accelerations and movements repeated at intervals less than 2 minutes; (2) fetal breathing episodes are independent of these gross changes; (3) beat-to-beat variation alters in a complex fashion and in different directions in association with physiologic changes.

Electrocardiography↗
PubMed2002

The importance of plasma apolipoprotein E concentration in addition to its common polymorphism on inter-individual variation in lipid levels: results from Apo Europe.

Interindividual variation in the concentration of plasma lipids which are associated with coronary artery disease (CAD) risk is determined by a combination of genetic and environmental factors. This study investigates the effects of apoE genotype and plasma concentration on cholesterol and triglycerides (TG) levels in subjects from five countries: Finland, France, Northern Ireland, Portugal, and Spain. Age and sex significantly influenced serum cholesterol, TG and apoE concentrations. The age effect differs in males and females. The allele frequencies of the apoE gene, one of the most widely studied CAD susceptibility genes, were determined: the epsilon2 allele frequency and the apoE concentration showed a north-south increasing gradient while the epsilon4 allele frequency showed the reverse. ApoE plays an important role in lipid metabolism. Total cholesterol and TG concentrations were significantly dependent on apoE genotype in both sexes. These differences in lipids between genotypes were more pronounced when plasma apoE concentrations were taken into account.

Adult↗
PubMed2002

Anatomic variations related to decompression of the common peroneal nerve at the fibular head.

Peroneal nerve decompression at the fibular head may be anticipated to be performed more often because lower extremity peripheral nerve surgery is used to restore sensation to the feet of diabetic patients. Although the basic concept of releasing the fascia of the peroneus longus is well-known, anatomic variants related to the peroneus muscle have been identified that must be included in the technique for decompression of this nerve. A comparison of these anatomic variants was done between a random selection of 29 cadavers (bilateral) and 65 patients who underwent unilateral peroneal decompression to treat symptoms of that compression. A fibrous band on the undersurface of the superficial head of the peroneus longus was found in 30% of the cadavers and it was found in 78.5% of the patients. The mean width of the band in cadavers was 9.1 mm and in patients it was 10.1 mm. A fibrous band on the superficial surface of the deep head of the peroneus longus was found in 43% of cadavers, and it was found in 20% of the patients. The soleus muscle origin was joined to the peroneus muscle origin in 9% of cadavers and it was noted in 6% of the patients. It is suggested that during surgical decompression of the common peroneal nerve at the fibular head, the surgeon be aware of these anatomic variants so that they may be released appropriately.

Decompression, Surgical↗
PubMed2005

Risk for HIV-1 infection associated with a common CXCL12 (SDF1) polymorphism and CXCR4 variation in an African population.

CXC chemokine ligand 12 (CXCL12), or stromal cell-derived factor 1 (SDF1), is the only known natural ligand for the HIV-1 coreceptor, CXC chemokine receptor 4 (CXCR4). A single nucleotide polymorphism (SNP) in the CXCL12 gene (SDF1-3'A) has been associated with disease progression to AIDS in some studies, but not others. Mutations in the CXCR4 gene are generally rare and have not been implicated in HIV-1/AIDS pathogenesis. This study analyzed the SDF1-3'A SNP and performed mutation screening for polymorphic markers in the CXCR4 gene to determine the presence or absence of significant associations with susceptibility to HIV-1 infection. The study consisted of 257 HIV-1-seropositive patients and 113 HIV-1-seronegative controls representing a sub-Saharan African population belonging to the Xhosa ethnic group of South Africa. The SDF1-3'A SNP was associated with an increased risk for HIV-1 infection (P = 0.0319) whereas no significant association was observed between the occurrence of the SDF1-3'A SNP and increased or decreased plasma levels of CXCL12. Comprehensive mutation analysis of the CXCR4 gene confirmed a high degree of genetic conservation within the coding region of this ancient population.

Black People↗
PubMed1987

Common mechanism controlling phase and antigenic variation in pathogenic neisseriae.

The expression of the Neisseria gonorrhoeae opacity protein (Op, protein II), a major antigenic determinant of the outer membrane, is subject to frequent phase transitions. At least nine expression loci (opaE) are involved in the production of a large number of serologically distinct Op types. Using opa-specific oligonucleotides as probes in genomic blots, we detect Op-related gene sequences (opr) in N. meningitidis as well as in N. lactamica. DNA sequence analysis of such opr genes derived from N. meningitidis reveals distinct regions of homology with gonococcal opa E genes. As shown in the immunoblot, the proteins encoded by opa and opr are serologically related. Like the opaE genes, the 5'-coding sequences of the opr genes include a repetitive sequence composed of pentameric CTCTT units. The number of these coding repeat (CR) units is variable. This finding, together with the observation that all opr genes are constitutively transcribed, regardless of the status of protein production, suggests a translational control mechanism identical to that of the opa genes in gonococci. The related structures and control mechanisms of opa and opr genes imply a general significance of their gene products for the pathogenic character of the investigated Neisseria species.

Amino Acid Sequence↗
PubMed2004

Global genetic analysis.

The introduction of molecular markers in genetic analysis has revolutionized medicine. These molecular markers are genetic variations associated with a predisposition to common diseases and individual variations in drug responses. Identification and genotyping a vast number of genetic polymorphisms in large populations are increasingly important for disease gene identification, pharmacogenetics and population-based studies. Among variations being analyzed, single nucleotide polymorphisms seem to be most useful in large-scale genetic analysis. This review discusses approaches for genetic analysis, use of different markers, and emerging technologies for large-scale genetic analysis where millions of genotyping need to be performed.

Animals↗
PubMed2003

Cis-acting variation in the expression of a high proportion of genes in human brain.

Much of the genetic component of human phenotypic diversity, including susceptibility to disease, is proposed to be the result of cis-acting influences on gene expression. If this hypothesis is correct, it implies that cis-acting regulatory variation is a common phenomenon. However, direct evidence in support of this view is scarce. We have applied highly quantitative measures of allele-specific expression in order to screen an average of 19 informative subjects (range 8-26) for the presence of common cis-acting influences on the expression of 15 genes by using RNA derived from human brain. We found that, in seven of the 15 assayed genes, at least one individual exhibited relative differences in allelic expression of 20% or more and, in one gene (DTNBP1), allelic expression differences exceeded 50%. These results suggest that cis-acting variation in gene expression commonly occurs in native tissue and hence provide empirical support for the hypothesis that this is potentially an important mechanism underlying human phenotypic diversity.

Alleles↗
PubMed2000

Seasonal variations and maturity stages in relation to differences in serum levels of gonadal steroids, vitellogenin, and thyroid hormones in the common dentex (Dentex dentex).

Seasonal variations in serum concentrations of 17beta-estradiol (E(2)), vitellogenin (Vg), testosterone (T), 11 ketotestosterone (11-KT), and thyroid hormones (T(4), l-thyroxine; and T(3), 3,5, 3'-triiodo-l-thyronine) were investigated during the first, second, and third reproductive cycles in intensively reared populations of common dentex, Dentex dentex, and correlated with gonadal development and spawning. In females, there were baseline E(2) values (<0.10 ng/ml) and negligible Vg concentrations during the postspawning and pregametogenesis period (June to December), and these increased thereafter to peak during the spawning period. Maximum T(3) and T(4) serum concentrations were found around spawning. There was a positive correlation during vitellogenesis and final maturation between Vg and T(3) (r(2) = 0.366). In addition, Vg and T(3) concentrations were statistically higher in the stages of vitellogenesis and final maturation than at the other stages (P<0.001). Minimum T(3) and T(4) concentrations (October) coincided with the decrease in water temperature and the associated decrease in the daily feeding rate and the specific growth rate. In males, as in females, seasonal changes in serum levels of T and 11-KT were well correlated with gonadal development. The presence of males in the stage of completed spermiogenesis in December coincided with the surge in both androgens and this increase lasted until the end of the spawning period. There were no significant differences in serum T(3) and T(4) levels among the maturity stages. The observed seasonal changes in serum gonadal steroids and Vg reflected the pattern of oocyte development and the spawning behavior of common dentex and were typical of the patterns described in most multiple spawners studied to date. Thyroid hormones may enhance early ovarian development and stimulate vitellogenesis in female dentex.

Aging↗
PubMed2003

Haplotype motifs: an algorithmic approach to locating evolutionarily conserved patterns in haploid sequences.

The promise of plentiful data on common human genetic variations has given hope that we will be able to uncover genetic factors behind common diseases that have proven difficult to locate by prior methods. Much recent interest in this problem has focused on using haplotypes (contiguous regions of correlated genetic variations), instead of the isolated variations, in order to reduce the size of the statistical analysis problem. In order to most effectively use such variation data, we will need a better understanding of haplotype structure, including both the general principles underlying haplotype structure in the human population and the specific structures found in particular genetic regions or sub-populations. This paper presents a probabilistic model for analyzing haplotype structure in a population using conserved motifs found in statistically significant sub-populations. It describes the model and computational methods for deriving the predicted motif set and haplotype structure for a population. It further presents results on simulated data, in order to validate the method, and on two real datasets from the literature, in order to illustrate its practical application.

Algorithms↗
PubMed1992

Heritable variation for sex ratio under environmental sex determination in the common snapping turtle (Chelydra serpentina).

The magnitude of quantitative genetic variation for primary sex ratio was measured in families extracted from a natural population of the common snapping turtle (Chelydra serpentina), which possesses temperature-dependent sex determination (TSD). Eggs were incubated at three temperatures that produced mixed sex ratios. This experimental design provided estimates of the heritability of sex ratio in multiple environments and a test of the hypothesis that genotype x environment (G x E) interactions may be maintaining genetic variation for sex ratio in this population of C. serpentina. Substantial quantitative genetic variation for primary sex ratio was detected in all experimental treatments. These results in conjunction with the occurrence of TSD in this species provide support for three critical assumptions of Fisher's theory for the microevolution of sex ratio. There were statistically significant effects of family and incubation temperature on sex ratio, but no significant interaction was observed. Estimates of the genetic correlations of sex ratio across environments were highly positive and essentially indistinguishable from + 1. These latter two findings suggest that G x E interaction is not the mechanism maintaining genetic variation for sex ratio in this system. Finally, although substantial heritable variation exists for primary sex ratio of C. serpentina under constant temperatures, estimates of the effective heritability of primary sex ratio in nature are approximately an order of magnitude smaller. Small effective heritability and a long generation time in C. serpentina imply that evolution of sex ratios would be slow even in response to strong selection by, among other potential agents, any rapid and/or substantial shifts in local temperatures, including those produced by changes in the global climate.

Animals↗