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PubMed1993

Understanding aspects of pictures: the development of scene schemata in young children.

The focus of this research was on preschool children's understanding of information depicted in pictures. Children were presented tasks assessing their understanding of object likelihoods, object positions, object sizes, and depth in scenes. The results indicated that knowledge about object likelihoods and positions show parallel patterns of development and share significant common variation, suggesting that they are early-developing aspects of scene schemata. Knowledge about size and depth seem to develop more slowly and were related to knowledge about object likelihoods only for older preschool children. Size and depth do not appear to form part of the scene schemata of young children.

Attention↗
PubMed2004

The future of association studies: gene-based analysis and replication.

Historically, association tests were limited to single variants, so that the allele was considered the basic unit for association testing. As marker density increases and indirect approaches are used to assess association through linkage disequilibrium, association is now frequently considered at the haplotypic level. We suggest that there are difficulties in replicating association findings at the single-nucleotide-polymorphism (SNP) or the haplotype level, and we propose a shift toward a gene-based approach in which all common variation within a candidate gene is considered jointly. Inconsistencies arising from population differences are more readily resolved by use of a gene-based approach rather than either a SNP-based or a haplotype-based approach. A gene-based approach captures all of the potential risk-conferring variations; thus, negative findings are subject only to the issue of power. In addition, chance findings due to multiple testing can be readily accounted for by use of a genewide-significance level. Meta-analysis procedures can be formalized for gene-based methods through the combination of P values. It is only a matter of time before all variation within genes is mapped, at which point the gene-based approach will become the natural end point for association analysis and will inform our search for functional variants relevant to disease etiology.

Alleles↗
PubMed2005

Automatic detection of cardiac waves on fetal magnetocardiographic signals.

Fetal magnetocardiography (fMCG) provides fetal cardiac traces useful for the prenatal monitoring of fetal heart function. In this paper, we describe an analytical model (ACWD) for the automatic detection of cardiac waves boundaries that works on fetal signals reconstructed from fMCG by means of independent component analysis. ACWD was validated for 45 healthy and 4 arrhythmic fetuses ranging from 22 to 37 weeks; ACWD outcomes were compared with the estimates of three independent investigators. Descriptive statistics were used to assess correspondence between the outcomes of the automatic and manual approaches. The parametric two-tailed Pearson correlation test (alpha=0.01) was employed to quantify, by means of the coefficients of determination, the amount of common variation between the sequences of intervals quantified automatically and manually. ACWD performances on short and long rhythm strips were investigated. ACWD demonstrated to be a robust tool providing dependable estimates of cardiac intervals and their variability during the third gestational trimester also in case of fetal arrhythmias. SNR and stability of fetal traces were the factors limiting ACWD performances. ACWD computation time, which was approximately 1:600 with respect to the manual procedure, was comparable with the time required for fCTI estimation on averaged beats.

Algorithms↗
PubMed1990

Defining target sequences of DNA-binding proteins by random selection and PCR: determination of the GCN4 binding sequence repertoire.

We developed a simple and accurate method to define the sequence recognition properties of DNA-binding proteins. The method employs polymerase chain reaction (PCR) amplification of sequences selected from a mixture of random oligonucleotides by the gel mobility-shift assay. We used this method to define the sequence requirement of the binding domain of the yeast transcriptional activator GCN4. Using a total of 200 ng of purified protein and four cycles of binding and subsequent amplification, we identified the TGA-(C/G)TCA sequence as the binding consensus of GCN4, which is consistent with the previously reported recognition sequence. In addition, our data indicate that GCN4 can bind with lower affinity to sequences that differ from the optimal sequence in one or even two positions. The most common variation was the C to A at position +2. The majority of the substitutions that still allowed binding were 3' to the central C residue indicating that the two sides of the palindromic recognition sequence are not equivalent.

Base Sequence↗
PubMed2005

Preferences and practices related to vaginal lubrication: implications for microbicide acceptability and clinical testing.

BACKGROUND: Research on vaginal microbicides for HIV prevention is progressing rapidly; the first large-scale effectiveness trials were launched in 2004. The majority of candidate microbicides are formulated as gels, which will act as lubricants when used during sex. Preferences and practices regarding lubrication during sex, therefore, likely influence microbicide acceptability and use. Researchers seek to maximize consistent and correct use of candidate microbicides during clinical trials to enable valid estimates of product effectiveness, and if proven effective, microbicides will be widely used only if acceptable. METHODS: We conducted a comprehensive literature review and interviewed 13 key informants from nine countries in Africa, Asia, Latin America, and North America. RESULTS: We found that norms and practices regarding lubrication during sex exist in many different countries. Despite significant variation, common themes emerged. In the majority of countries, women's genital hygiene is highly valued, and women are expected to achieve a moderate amount of vaginal lubrication during sex that is neither excessive nor inadequate. Women may try to achieve this by engaging in a wide variety of vaginal practices. CONCLUSIONS: Even though some informants expressed concerns about the acceptability of lubricating microbicides in some settings, they thought that microbicides should be developed, that women and men may be willing to accept a certain level of increased lubrication in exchange for protection from HIV, and that lubricating microbicides may be considered more acceptable when perceived as genital hygiene products. Recommendations are made on how to take vaginal practices into account during clinical testing of microbicides.

Administration, Intravaginal↗
PubMed2005

TP53 mutation, allelism and survival in non-small cell lung cancer.

TP53 is well-recognized as a mutational target in cancers and common variation in the TP53 gene has been investigated as potentially contributing to cancer susceptibility. The codon 72 polymorphism has been proposed to alter the phenotype of TP53 mutations, and TP53 mutations have been reported to occur preferentially on the arginine allele. Using a consecutive case series of non-small cell lung cancer we have investigated whether TP53 mutations occur preferentially on the arginine or proline allele, and whether the combination of mutation and allelism confers differences in the clinical phenotype. The overall prevalence of TP53 mutation was 26% (76/293). The majority of mutations occurred on the arginine allele (51/60, 85%), and there was corresponding strong selection for loss of the proline allele [87% of loss of heterozygosity (LOH) events were loss of proline]. However, there was no statistically significant difference in the prevalence of mutation by constitutional genotype and among heterozygotes with LOH, TP53 mutation prevalence did not differ by the codon 72 polymorphism (48% on arginine versus 40% on proline). Importantly, patient survival did significantly differ: those patients having a TP53 mutation on the proline allele had the worst survival outcomes (hazards ratio = 2.6, P < 0.03). Further, this phenotype was limited to those patients with advanced disease, where mutation on the proline allele was associated with a significantly worse outcome compared with those without mutation or with mutation on the arginine allele (P < 0.001). Our data suggest that there are selective pressures for loss of the TP53 proline allele in non-small cell lung cancer. Further, the combination of mutation with the codon 72 proline variant predicts poorer patient survival, particularly in a disease that has progressed outside the lung, a finding that warrants further investigation.

Adenocarcinoma↗
PubMed2003

Mitochondrial DNA diversity in South America and the genetic history of Andean highlanders.

We analyzed mtDNA sequence variation in 590 individuals from 18 south Amerindian populations. The spatial pattern of mtDNA diversity in these populations fits well the model proposed on the basis of Y-chromosome data. We found evidence of a differential action of genetic drift and gene flow in western and eastern populations, which has led to genetic divergence in the latter but not in the former. Although it is not possible to identify a pattern of genetic variation common to all South America, when western and eastern populations are analyzed separately, the mtDNA diversity in both regions fits the isolation-by-distance model, suggesting independent evolutionary dynamics. Maximum-likelihood estimates of divergence times between central and south Amerindian populations fall between 13,000 and 19,000 years, which is consistent with a Pleistocenic peopling of South America. Moreover, comparison of among-population variability of mtDNA and Y-chromosome DNA seems to indicate that South America is the only continent where the levels of differentiation are similar for maternal and paternal lineages.

Chromosomes, Human, Y↗
PubMed2005

Characterization of a cyclooxygenase-2-765G-->C promoter polymorphism in human neural cells.

Direct sequencing of the human cyclooxygenase-2 gene promoter revealed a common single nucleotide substitution, cyclooxygenase-2-765G-->C, in 24.5% of the populations analyzed. This change introduced a 20 base pair polypyrimidine/polypurine element and a partial recognition feature for RXRalpha, the 9-cis retinoic acid receptor, into the polymorphic promoter. Cyclooxygenase-2-765G-->C constructs, when transfected into human neural cells, exhibited a 1.4-fold higher level of basal expression, while the proinflammatory factors interleukin-1beta and 9-cis retinoic acid synergistically induced polymorphic promoter activity 2.4-fold over wild type. These results suggest that under specific conditions of cellular stress, a common variation in cyclooxygenase-2 promoter structure may enhance cyclooxygenase-2 transcription, and this may contribute to the proliferation of an inflammatory response in brain cells.

Base Sequence↗
PubMed1992

Distribution of the posterior ciliary arteries revealed after vascular occlusions. A case report.

Recognized posterior ciliary artery occlusion combined with central retinal artery occlusion is relatively uncommon. Clinical and experimental evidence of combined occlusions appear to support a nasal and temporal distribution for the posterior ciliary arteries in most cases. A case involving a patient in whom the posterior ciliary arteries divided superiorly and inferiorly to supply the region of the macula is reported. Some of the more common variations in the distribution of the posterior ciliary arteries are discussed. Clinicians should be aware that the territorial divisions of the choroidal perfusion in the macula may be horizontally based.

Arterial Occlusive Diseases↗
PubMed1989

Clinical assessment of a published model to predict aminoglycoside-induced nephrotoxicity.

During the past decade, several patient risk factors have been identified as contributing to the development of aminoglycoside nephrotoxicity. Sawyers et al. recently published a method for estimating the probability of aminoglycoside nephrotoxicity on an individual patient basis. The present work represents a refinement of previous publications and has not been tested with the common variations used in aminoglycoside dosing. The purpose of this study was to determine both the qualitative and quantitative value of this method in predicting aminoglycoside induced nephrotoxicity. Eighty-three patients (47 male, 36 female) meeting the inclusion criteria of Sawyers et al. were entered into the study. Patient risk factors (age, sex, initial 1-h postinfusion aminoglycoside serum level, initial calculated creatinine clearance, duration of therapy, and presence of liver disease) were entered into a logistic regression analysis to determine the individual patient's risk of developing nephrotoxicity. These calculated probability scores were then compared with the observed nephrotoxicity in specific groups within our patient sample to see how effectively the model quantitatively performed. Twelve patients (14.5%) developed nephrotoxicity. The model predicted only 5 of the 12 patients developing nephrotoxicity (sensitivity or true positive = 42%). In the nonnephrotoxic group, the model accurately predicted only 38 of 71 patients (specificity or true negative = 54%). These data suggest that the model may accurately quantitate the number of patients likely to develop nephrotoxicity from a specific group but is unable to discriminate specific patients at risk of developing aminoglycoside-induced nephrotoxicity.

Adolescent↗
PubMed1995

The rotator cuff.

The functional anatomy of the rotator cuff and its relationship to the mechanism of shoulder joint movements and control is now becoming more clearly understood. Common variations in the anatomy of the acromion and the subacromial region, particularly the coraco-acromial ligament, and its relationship to the tendon of the supraspinatus are now seen to be major determinants of degenerative changes in the rotator cuff. Changes in the matrix of the musculotendinous region, which may be related to mechanical interference with the vascular supply to the tendon are now a possible determinant of early degenerative changes (both primary, and those secondary to trauma) in the rotator cuff. The relationship of these findings to the management of lesions of the rotator cuff is discussed.

Humans↗
PubMed1996

Regulatory mutations in human lipoprotein disorders and atherosclerosis.

Most known mutations underlying human lipoprotein abnormalities affect the protein coding sequence of the gene involved. Mutations in the regulatory regions-promoters, enhancers, binding sites for transcription factors and other elements-may markedly alter the transcription efficiency of lipid-regulatory genes, and may thus cause an inherited defect of lipoprotein metabolism. Reported examples include mutations of the promoters of the human LDL and lipoprotein lipase genes. Common variation of the DNA sequence in the promoter region, such as that occurring in the human apolipoprotein A-I and plasminogen activator inhibitor(-1) genes, may account for subtle differences in serum lipid levels and risk of atherosclerotic vascular disease in the general population.

Apolipoprotein C-III↗
PubMed2004

Anatomy of the external nasal nerve.

After rhinoplasty, many patients report numbness of the nasal tip. This is primarily because of injury to the external nasal nerve. It is imperative that surgeons performing rhinoplasty be familiar with the anatomy and the common variations of this nerve. Therefore, the purpose of this study was to present an anatomical study of the external nasal nerve. Twenty external nasal nerves were examined by dissecting 10 fresh cadaver noses within 48 hours of death. On dissection, the exit of the nerve between the nasal bone and upper lateral cartilage was identified. The distance from the point of exit to the midline of the nose and the size of the nerve were measured. The course and the running plane of the nerve were investigated. The nerve branchings were also classified into three types: type I, only one nerve without any branch; type II, one nerve proximally and then splitting into two main branches at the intercartilaginous junction; and type III, two main branches from the point of exit. The point of exit of the external nasal nerve from the distal nasal bone was located 6.5 to 8.5 mm (7.3 +/- 0.6 mm) lateral to the nasal midline. The average diameter of the nerve at the point of exit was 0.35 +/- 0.036 mm. Most of the nerves (95 percent) passed through the deep fatty layer directly under the nasal superficial musculoaponeurotic layer, all the way down to the alar cartilages. In terms of the branching type, type I was observed in 10 of 20 nerves (50 percent), type II was observed in six of 20 (30 percent), and type III was seen in four of 20 (20 percent). On the basis of the results of this study, the following precautions are suggested during a rhinoplasty to minimize the chance of injury to this nerve. First, it is best to avoid deep intercartilaginous or intracartilaginous incisions so that the deep fatty layer is not invaded and the dissection is maintained directly on the surface of the cartilage (deep to the nasal superficial musculoaponeurotic layer). Second, dissection at the junction of the nasal bone and upper lateral cartilage area of one side should be limited to within 6.5 mm from the midline. Lastly, when the nasal dorsum is augmented by an onlay graft, implants or grafts less than 13 mm wide at the rhinion level should be used.

Aged↗
PubMed2005

Superficial dorsal artery of the forearm: case report and review of the literature.

Although abnormalities of vascular anatomy in the forearm are common, variations of the radial and ulnar arteries are rare. Nevertheless, arterial variants in the forearm may present clinically with neurovascular signs or symptoms. Even when anomalous arteries are not apparent, they may complicate surgery of the forearm and hand, as well as reconstructive surgery that involves the harvest of radial or ulnar artery-based forearm free flaps. For example, the superficial ulnar artery has an incidence of 2.7% and has been well described as a "hidden trap" in the harvest of radial forearm flaps. We present a case report of a variant of the radial artery-the superficial dorsal artery of the forearm. This artery has an estimated incidence of 0.75% and is associated with either an absent or small-caliber radial artery. We believe this is the first report of such an artery presenting to clinical attention, as well as the first imaging of this structure with magnetic resonance angiography. The embryology of this structure and its clinical implications to the hand surgeon, peripheral vascular surgeon, and reconstructive microsurgeon, are also discussed.

Adult↗
PubMed2003

Persistent left superior vena cava: an intensivist's experience and review of the literature.

Persistent left superior vena cava is a relatively rare vascular anomaly. It is, however, the most common variation in the thoracic venous system. The anomaly is typically detected on chest x-ray after the placement of a pulmonary artery catheter or pacemaker leads. This report describes a case of persistent left superior vena cava detected after successful placement of a pulmonary artery catheter.

Catheterization, Swan-Ganz↗
PubMed2000

Analysis of human papillomavirus type 16 E6 variants in relation to p53 codon 72 polymorphism genotypes in cervical carcinogenesis.

This study aimed to assess the role of specific human papillomavirus type 16 (HPV-16) variants, in combination with p53 codon 72 polymorphism genotypes, in cervical carcinogenesis. An initial sequence analysis of HPV-16 long control, E6 and E7 regions of 53 well-defined cervical samples containing HPV-16 revealed that a T to G transition at nucleotide position 350 within the E6 open reading frame was the most common variation, the frequency of which seemed to decrease with increasing severity of the lesion. Therefore, a total of 246 cervical samples of residents of The Netherlands was specifically analysed for HPV-16 350G/T variants and/or p53 codon 72 genotypes. These comprised HPV-negative normal cervical scrapes (n=40), normal cervical scrapes containing HPV-16 (n=46), scrapes containing HPV-16 from women with abnormal cervical cytology participating in a non-intervention follow-up study without (n=38) and with (n=51) a histologically proven cervical intraepithelial neoplasia (CIN) III lesion at the end of the study, and cervical squamous cell carcinomas (n=71). Neither specific HPV-16 350G/T variants nor specific p53 genotypes were associated with a higher risk of developing CIN III or cervical cancer. However, HPV-16 350T variants were significantly over-represented in p53 Arg homozygous women with cervical cancer. This suggests that, in p53 Arg/Arg women, infection with HPV-16 350T variants confers a higher risk of cervical cancer.

Base Sequence↗
PubMed2004

Enhanced motility of a Proteus mirabilis strain expressing hybrid FlaAB flagella.

Proteus mirabilis has two tandemly arranged flagellin-encoding genes, flaA and flaB. flaA is transcribed from a sigma(28) promoter, while flaB is silent. flaA and flaB can undergo reversible rearrangement to produce a set of hybrid genes referred to as flaAB. Flagellins composed of FlaAB protein have a different amino acid sequence and are antigenically distinct from flagellin composed of FlaA, implicating flagellin gene conversion as a putative virulence mechanism for P. mirabilis. The change in amino acid sequence is also hypothesized to alter the filament helix and, hence, affect the motility of FlaAB-expressing strains. To test this hypothesis, the motility of wild-type P. mirabilis was compared with that of a strain, DF1003, locked into the FlaAB(+) hybrid phase, under conditions of altered ionic strength, pH and viscosity. Cell motion tracking analysis showed that DF1003 has wild-type swimming velocity at physiological conditions, but moves significantly faster and travels further compared to the wild-type at NaCl concentrations greater than 170 mM. DF1003 is also significantly faster than the wild-type at pH 5.2, 5.8 and 8.2, and at 5 and 10 % polyvinylpyrrolidone. Measurements of amplitude and wavelength for isolated flagella subjected to pH 5.8 or 425 mM NaCl showed a loss of helical structure in FlaA flagella compared to FlaAB filaments, a feature that could significantly affect motility under these conditions. These results support a hypothesis that FlaAB flagellin imparts a motile advantage to P. mirabilis in conditions that otherwise may impede bacterial movement. In a broader context, flagellar antigenic variation, commonly thought to serve as means to avoid host defences, may also enhance motility in other bacterial species, thus aiding in the adaptation and survival of the cells.

Amino Acid Sequence↗
PubMed1983

Characterization of the proteins of human hair and nail by electrophoresis.

Low-sulfur and high-sulfur proteins from human hair and nail were characterized by two-dimensional polyacrylamide gel electrophoresis. Apparent molecular weights (estimated by SDS electrophoresis) of low-sulfur and high-sulfur proteins were in the ranges 55,500-76,000 and 26,500-43,000, respectively, but these are probably higher than the real values (12-30% for low-sulfur, 75-150% for high-sulfur) because corresponding wool proteins behave anomalously in SDS electrophoresis. Isoelectric points of the low-sulfur proteins ranged from 4.9-5.4. Six low-sulfur and 7 high-sulfur major proteins were common to hair and nail from the same individual, but each keratin contained 1 additional major low-sulfur component which was not common. Variation, presumably of genetic origin, was observed in the low-sulfur and high-sulfur proteins of hair and nail.

Chemical Phenomena↗