SEARCH · PubMed Health

Results for “shared variables”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,207 records · Page 67Linked to original sources

PubMed2002

Genetic diversity and evolution of the human leptin locus tetranucleotide repeat.

To better understand the evolutionary history of the gene region containing the multifunctional adipose tissue hormone leptin, we genotyped 1,957 individuals from 12 world populations for a highly variable tetranucleotide repeat polymorphism located 476 bp 3' of exon 3 of the leptin gene. Common alleles shared among populations, alleles specific to geographically defined populations, and the homologous alleles in the common and pygmy chimpanzee, the gorilla and the orangutan, were sequenced to define the allelic variation at the nucleotide level. These data reveal a common set of alleles shared among world populations, presumed to have arisen from a great ape ancestral allele prior to the divergence of the major geographical subdivisions of the human population, a subset of alleles specific to populations of African ancestry and a second set of alleles that arose by tandem duplication of the core repeat unit following the separation of African and non-African populations. These findings emphasize the complex evolutionary history of this locus and raise cautions about the pooling of alleles at this locus in association studies.

Animals↗

PubMed1989

Monoclonal antibodies for specific immunoperoxidase detection of Campylobacter pylori.

Monoclonal antibodies were raised against Campylobacter pylori to detect the organism in clinical specimens by the immunoperoxidase technique. Twenty-one hybridoma cultures obtained were screened on tissue sections of gastric mucosa to identify antibodies that did not cross-react with host cells. To select antibodies with high grade of specificity to C. pylori, hybridomas were also screened by an enzyme-linked immunosorbent assay against a wide panel of gram-negative bacteria. Fifteen antibodies showed a variable grade of cross-reactivity with gastric mucosa, indicating the presence of at least three epitopes shared by C. pylori and epithelial cells. Three of the six antibodies non-reacting with gastric mucosa (CB-1, CB-26, and CB-31) also were found to be specific for C. pylori. Using CB-26 in an indirect immunoperoxidase test, gastric brushings from 60 patients consecutively undergoing endoscopic examination were examined. By light microscopy, we observed the presence of large amounts of C. pylori in smears from all the 32 patients with positive culture. A small number of bacterial cells were also seen in 8 of 28 patients whose cultures were negative. These findings suggest that the monoclonal antibody CB-26 might be of value for rapid and specific detection of C. pylori.

Animals↗

PubMed1987

Sera from Cameroon recognize proteins of Plasmodium falciparum isolates from geographically diverse areas of the world.

Immunological reactions of clinically-defined sera collected from 176 children and adults (3 to 63 years of age) living in malaria endemic regions of Cameroon were evaluated by ELISA, growth inhibition studies and immunoprecipitation assays using different parasite isolates from geographically diverse areas. The proportions of sera positive by ELISA and with positive growth inhibitory activity tended to increase with increased age. SDS-PAGE analyses of immunoprecipitates using [35S]methionine labelled parasite polypeptides revealed that a wide range of proteins was recognized by the sera. There were many similarities in the patterns of antigens immunoprecipitated in the different isolates, particularly when immune sera were used. Variability in response was more evident in sera collected from children. These findings suggest that strains may share components which generate protective immunity.

Adolescent↗

PubMed1991

Comparison of the effects of buspirone and chlordiazepoxide on successive discrimination.

Buspirone is a novel anxiolytic which does not share the muscle relaxant, anticonvulsant and sedative properties of classical anxiolytics such as the benzodiazepines. It has variable effects in conflict tasks based on shock which normally show consistent effects with classical anxiolytics. The present experiment investigated the effects of buspirone on successive discrimination, a conflict task employing omission of reward rather than shock. Buspirone (3.3, 1.1 and 0.3 mg/kg, IP) and chlordiazepoxide (5 and 20 mg/kg, IP) were administered to separate groups of rats throughout acquisition of a visual successive discrimination. Chlordiazepoxide released nonrewarded responding in a dose-related fashion. The effects of buspirone were qualitatively similar in releasing response suppression but were both less in magnitude and less clearly related to dose. The experiment shows that the action of buspirone in successive discrimination tasks does not depend on the use of shock but, rather, appears to be a genuine failure to fully release behavioural inhibition.

Animals↗

PubMed1990

Food intake and selection pattern of rats treated with dexfenfluramine, fluoxetine and RU 24969.

The effects of two indirect (dexfenfluramine and fluoxetine) and one direct (RU 24969) serotonergic agonists on diet selection over a 12-hr period were examined. Rats were habituated to eat, during the dark period, from two isoenergetic diets that differed in carbohydrate and protein content. Drugs were injected intraperitoneally at 1845 hr, 15 min prior to food access. The drugs exerted their effects mainly during the first hour of feeding (1900-2000 hr). At this time, a selective suppression in intake of the high carbohydrate-low protein diet was the most prominent characteristic of all three serotonergic agonists. This macronutrient specific effect was particularly strong at low dosages (dexfenfluramine, fluoxetine and RU 24969: 0.5, 2.0 and 1.0 mg/kg, respectively). With time, as the effect of drugs wore off, diet selection pattern became more variable. The fact that both indirect 5-HT agonists and a direct selective 5-HT receptor agonist share a specific behavioral effect provides additional support for the role of serotonin in the control of macronutrient specific appetites.

Animals↗

PubMed2006

Is biopsy Gleason score independently associated with biochemical progression following radical prostatectomy after adjusting for pathological Gleason score?

PURPOSE: Biopsy Gleason score is known to be associated with prostate specific antigen failure following radical prostatectomy. However, it is unclear whether it remains associated with outcome after surgery when the pathological Gleason score is known. MATERIALS AND METHODS: We determined the association between biopsy Gleason score and biochemical progression after correcting for preoperative and postoperative characteristics, including pathological Gleason score, in 1,931 men treated with radical prostatectomy between 1988 and 2005 in the Shared Equal Access Regional Cancer Hospital Database Study Group database. Gleason score was examined as a categorical variable of 2 to 6, 3 + 4 and 4 + 3 or greater. RESULTS: Higher biopsy Gleason scores were positively associated with extracapsular extension (p <0.001), positive surgical margins (p <0.001), seminal vesicle invasion (p <0.001), positive lymph nodes (p <0.001) and biochemical progression (log rank p <0.001). After adjusting for only preoperative characteristics biopsy Gleason 3 + 4 and 4 + 3 or greater were associated with increased risk of biochemical progression compared to biopsy Gleason 6 or less (p = 0.001 and <0.001, respectively). After further adjusting for multiple pathological characteristics, including pathological Gleason score, the association between higher biopsy Gleason score and progression was little changed, in that men with biopsy Gleason 3 + 4 and 4 + 3 or greater were significantly more likely to experience progression (p = 0.001 and <0.001, respectively). Furthermore, when stratified by pathological Gleason score, higher biopsy Gleason scores were associated with an increased risk of biochemical progression in each pathological Gleason score category (log rank p </=0.007). CONCLUSIONS: Biopsy Gleason score remained strongly associated with progression even when the pathological Gleason score was known and controlled for. If confirmed at other centers, incorporation of biopsy Gleason score into postoperative nomograms designed to estimate the progression risk might improve model precision.

Aged↗

PubMed2004

Clinical presentation of interstitial lung disease in children.

Interstitial lung disease (ILD) in children represents a heterogeneous group of rare lung disorders characterised by an inflammatory process of the alveolar wall and the pulmonary interstitium, which share common clinical, radiological and histological findings. Clinical presentation of paediatric ILD is non-specific and variable. Respiratory signs and symptoms include tachypnoea, rapid shallow breathing, retractions, cyanosis and crackles. Failure to thrive and respiratory distress are common in infants. Dyspnoea on exertion is a symptom encountered in older children. Non-respiratory symptoms can be present when ILD is part of a systemic disorder. Although non-specific and variable, the clinical presentation at the time of diagnosis has some prognostic value.

Child↗

PubMed1998

Neuronal and non-neuronal cell populations of the avian dorsal root ganglia express muscarinic acetylcholine receptors.

The distribution of muscarinic acetylcholine receptors was investigated by immuno-light and electron microscopy in the chick dorsal root ganglion during embryonic development (E12 and E18) and after hatching. The monoclonal antibody we used recognizes the acetylcholine binding site shared by all five muscarinic acetylcholine receptor subtypes. At E12, light microscopy reveals several immunopositive neurons with variable degrees of immunolabeling, heterogeneously distributed throughout the ganglion. Later in development and after hatching, the intensity of immunolabeling seems to decrease and the immunopositive neurons, of the small-medium-sized type, are located mostly in the medio-dorsal region of the ganglion. Under the electron microscope, the immunoreaction is associated with the Nissl bodies, budding Golgi cisterns and, especially at E12, with discrete loci along the neuronal plasma membrane. Unmyelinated nerve fibers, in both central and peripheral branches, are also immunopositive, suggesting that muscarinic acetylcholine receptors are transported towards the spinal cord and the periphery, respectively. A large number of perineuronal satellite cells and both myelinating and unmyelinating Schwann cells are intensely labeled. These observations, combined with previous data on the pharmacological and functional characterization of muscarinic acetylcholine receptors in the avian dorsal root ganglion, suggest that both sensory neurons and non-neuronal cells are able to respond to acetylcholine stimuli. Since muscarinic acetylcholine receptor-immunoreactivity is restricted to the small-medium-sized neurons and their unmyelinated fibers, of the nociceptive type, we suggest that these receptors are involved in modulating the transduction of noxious stimuli from the periphery.

Animals↗

PubMed2005

A re-consideration of Pseudoperonospora cubensis and P. humuli based on molecular and morphological data.

Phylogenetic analysis of the ITS rDNA region was carried out with two economically important downy mildews, Pseudoperonospora cubensis, which infects species of Cucumis, Cucurbita, and Citrullus belonging to Cucurbitaceae, and P. humuli, which infects plants of the genus Humulus belonging to Cannabaceae. Two closely related species, P. cannabina and P. celtidis, were also included to reveal taxonomic relationships with the first two mildews. All four species formed a well-resolved clade when compared with the ITS sequences of other downy mildew genera, using Bayesian inference and maximum parsimony. The P. cubensis isolates obtained from different hosts and (or) geographical origins in Korea, exhibited no intraspecific variability in the ITS sequences. The phylogenetic analyses of P. cubensis and P. humuli showed that they share a high level of sequence homology; the morphology of the sporangiophores, sporangia, and dehiscence apparatus confirmed the similarity of the two species. We therefore reduce P. humuli to the status of a taxonomic synonym of P. cubensis.

DNA, Fungal↗

PubMed2004

The factors governing the thermal stability of frataxin orthologues: how to increase a protein's stability.

Understanding the factors governing the thermal stability of proteins and correlating them to the sequence and structure is a complex and multiple problem that can nevertheless provide important information on the molecular forces involved in protein folding. Here, we have carried out a comparative genomic study to analyze the effects that different intrinsic and environmental factors have on the thermal stability of frataxins, a family of small mitochondrial iron-binding proteins found in organisms ranging from bacteria to humans. Low expression of frataxin in humans causes Friedreich's ataxia, an autosomal recessive neurodegenerative disease. The human, yeast, and bacterial orthologues were selected as representatives of different evolutionary steps. Although sharing high sequence homology and the same three-dimensional fold, the three proteins have a large variability in their thermal stabilities. Whereas bacterial and human frataxins are thermally stable, well-behaved proteins, under the same conditions yeast frataxin exists in solution as an unstable species with apprechable tracts in a conformational exchange. By designing suitable mutants, we show and justify structurally that the length of the C-terminus is an important intrinsic factor that directly correlates with the thermal stabilities of the three proteins. Thermal stability is also gained by the addition of Fe(2+). This effect, however, is not uniform for the three orthologues nor highly specific for iron: a similar albeit weaker stabilization is observed with other mono- and divalent cations. We discuss the implications that our findings have for the role of frataxins as iron-binding proteins.

Amino Acid Sequence↗

PubMed2000

Highly reliable genetic identification of individual northern hairy-nosed wombats from single remotely collected hairs: a feasible censusing method.

The highly endangered northern hairy-nosed wombat (Lasiorhinus krefftii) is extremely difficult to study in the wild, and its numbers correspondingly difficult to estimate. Disturbance to the animals caused by trapping and radio-tracking may not only constitute an excessive risk to the population's viability, but may also yield biased data. The results of a pilot study are presented, which clearly show noninvasive genotyping to be a highly feasible and reliable alternative censusing method for L. krefftii. The protocol can identify individual wombats from single hairs collected remotely at burrow entrances, using: (i) a panel of microsatellite markers giving individual-specific genotypes; and (ii) a Y-linked sexing marker in combination with a single-copy X-linked amplification control. Using just the eight most variable microsatellites (of 20 available), only one in 200 pairs of full-sibs are predicted to share the same genotype. From 12 wombat hair samples collected on tape suspended over burrow entrances, three known female, two known male and an unknown wombat of each sex were identified. The approach will allow censusing of individuals that evade capture, and will also reveal some otherwise problematic aspects of the behaviour of this elusive animal.

Animals↗

PubMed2000

Liver transplant waiting time does not correlate with waiting list mortality: implications for liver allocation policy.

Factors associated with the risk for mortality once placed on the liver transplant waiting list and how this risk relates to center-specific waiting time and transplant activity have not been adequately evaluated. We performed this study to determine the association between center-specific waiting time and waiting list mortality among liver transplant candidates stratified by medical urgency at the time of registration. A Cox proportional hazards model was used to calculate 2-year mortality risk for a cohort of 16, 414 registrants added to the United Network for Organ Sharing liver transplant waiting list between January 1, 1997, and December 31, 1997. After controlling for confounding variables, we calculated the mortality risk for centers, organ procurement organizations (OPOs), and states. The relation between center-specific waiting list mortality risk and median waiting time or transplant activity was determined by linear regression. In multivariate analyses, higher initial medical urgency status (relative risk [RR] = 12.8; P <.001), increasing age (P <.001), black ethnicity (RR = 1.29; P <.001), history of previous transplant (RR = 1.2; P =.009), certain liver diagnoses, and smaller center size (RR = 1.39; P =.008) were associated with significantly increased waiting list mortality. Candidates with blood type A (RR = 0.87; P <.001) and those with cholestatic cirrhosis as the primary diagnosis (RR = 0.73; P < 0. 001) had a reduced risk for dying. There were significant variations in 2-year waiting list mortality risk among centers, OPOs, and states. However, when stratified by medical urgency status at waiting list entry, center-specific waiting time and transplantation rates accounted for almost none of the center-specific waiting list mortality. Although there are variations in waiting list mortality risk among centers, OPOs, and states, there is very little relation between center-specific waiting list mortality and center-specific median waiting time or center-specific transplantation rates when stratified by medical urgency. Waiting time and center transplant rates should not influence liver allocation policy.

Cohort Studies↗

PubMed1984

Gamma-crystallin family of the mouse lens: structural and evolutionary relationships.

The heterogeneity inherent among gamma-crystallins of the mouse lens was investigated by sequence analysis of three gamma-crystallin-specific cDNAs. Comparison of the nucleotide sequence of these cDNAs and one previously reported by us revealed that the four gamma-cDNAs share 80-90% homology in nucleotide sequence. The entire 3' half of the coding region shows more variability than the 5' half, whereas the greatest variability is observed in the 3' untranslated region where numerous base substitutions, deletions, and insertions seem to have occurred. Alignment of the amino acid sequences of the four mouse gamma-crystallins according to the known four structural motifs of the major calf gamma-crystallin, gamma-II, suggests that all four mouse polypeptides are structurally very similar to calf gamma-II. However, most of the mouse polypeptides differ from gamma-II by the absence of one amino acid residue, resulting in a shorter connecting peptide between the two globular domains of the protein. Primary sequence alignment also revealed that the four mouse gamma-crystallins are most divergent in the third structural motif of the polypeptide. The significance of these differences in terms of the structure and function of the gamma-crystallins in the mouse lens is discussed.

Amino Acid Sequence↗

PubMed1993

The major myosin-binding domain of skeletal muscle MyBP-C (C protein) resides in the COOH-terminal, immunoglobulin C2 motif.

A common feature shared by myosin-binding proteins from a wide variety of species is the presence of a variable number of related internal motifs homologous to either the Ig C2 or the fibronectin (Fn) type III repeats. Despite interest in the potential function of these motifs, no group has clearly demonstrated a function for these sequences in muscle, either intra- or extracellularly. We have completed the nucleotide sequence of the fast type isoform of MyBP-C (C protein) from chicken skeletal muscle. The deduced amino acid sequence reveals seven Ig C2 sets and three Fn type III motifs in MyBP-C. alpha-chymotryptic digestion of purified MyBP-C gives rise to four peptides. NH2-terminal sequencing of these peptides allowed us to map the position of each along the primary structure of the protein. The 28-kD peptide contains the NH2-terminal sequence of MyBP-C, including the first C2 repeat. It is followed by two internal peptides, one of 5 kD containing exclusively spacer sequences between the first and second C2 motifs, and a 95-kD fragment containing five C2 domains and three fibronectin type III motifs. The C-terminal sequence of MyBP-C is present in a 14-kD peptide which contains only the last C2 repeat. We examined the binding properties of these fragments to reconstituted (synthetic) myosin filaments. Only the COOH-terminal 14-kD peptide is capable of binding myosin with high affinity. The NH2-terminal 28-kD fragment has no myosin-binding, while the long internal 100-kD peptide shows very weak binding to myosin. We have expressed and purified the 14-kD peptide in Escherichia coli. The recombinant protein exhibits saturable binding to myosin with an affinity comparable to that of the 14-kD fragment obtained by proteolytic digestion (1/2 max binding at approximately 0.5 microM). These results indicate that the binding to myosin filaments is mainly restricted to the last 102 amino acids of MyBP-C. The remainder of the molecule (1,032 amino acids) could interact with titin, MyBP-H (H protein) or thin filament components. A comparison of the highly conserved Ig C2 domains present at the COOH-terminus of five MyBPs thus far sequenced (human slow and fast MyBP-C, human and chicken MyBP-H, and chicken MyBP-C) was used to identify residues unique to these myosin-binding Ig C2 repeats.

Amino Acid Sequence↗

PubMed2002

PLUNC: a novel family of candidate host defence proteins expressed in the upper airways and nasopharynx.

The upper respiratory tract, including the nasal and oral cavities, is the major route of entry of pathogens into the body, and early recognition of bacterial products in this region is critical for host defence. A well-established family of four proteins involved in this process are bactericidal/permeability-increasing protein (BPI) and lipopolysaccharide-binding protein (LBP), which are central to the host defence against bacteria, and cholesteryl ester transfer protein (CETP) and phospholipid transfer protein (PLTP), which have also been implicated in this response. In this paper, we demonstrate the existence of a related family of seven human proteins, which we designate PLUNC proteins. The PLUNC proteins are encoded by adjacent genes found within a 300 kb region of chromosome 20, suggesting that they may be under transcriptional control of shared genomic elements, and expression data shows that these proteins are found in overlapping regions of the pulmonary, nasopharyngeal and oral epithelium, sites where the previously described BPI family members are not expressed. Whereas the BPI family are predicted to share very closely similar three-dimensional structures, the PLUNC family is predicted to have much greater variability in the N-terminal domain, corresponding to the active domain of BPI, thus creating the notion of a BPI/PLUNC structural superfamily. We suggest that members of the PLUNC family may function in the innate immune response in regions of the mouth, nose and lungs, which are sites of significant bacterial exposure.

Amino Acid Sequence↗

PubMed2005

Population stress and the Swedish sex ratio.

Well-developed theory implies that the human secondary sex ratio moves inversely over time with the level of anxiety and depression in the population. Few tests of this hypothesis, however, appear in the voluminous literature concerned with the sex ratio. These tests, moreover, employ designs that allow only weak inference. We contribute to the literature by applying time-series methods to Swedish data for the 276 months beginning January 1974 to detect a relationship between the sex ratio and defined daily doses of antidepressants and anxiolytics dispensed to women. Consistent with theory, we find the drug variable inversely related to the sex ratio. We argue that the discovered association cannot be attributed to shared trends, cycles, or other forms of autocorrelation in the data, or to the problem of endogeneity that necessarily plagues studies based on samples of individual women and births. Implications include that surveillance systems might monitor dispensing of anxiolytics and antidepressants as a marker for population stress thought to be a risk factor for adverse pregnancy outcomes such as preterm delivery.

Anti-Anxiety Agents↗

PubMed1998

Cutaneous parachordoma. A light microscopic and immunohistochemical report of two cases and review of the literature.

Parachordomas are rare cutaneous tumors that show virtually identical histologic findings to chordomas. Therefore, the major differential diagnosis in a case of parchordoma is metastatic chordoma. Parachordomas are benign neoplasms and most often develop on the extremities adjacent to tendons, synovium or osseous structures, as opposed to chordomas, which are malignant tumors located along the craniospinal axis. While recurrences may occur in cases of parachordoma, metastases have not been reported. In this report, two cases of parachordomas are reported and the literature reviewed. By light microscopy, parachordomas show eosinophilic bands of fibrous tissue separating lobules of cells with variably vacuolated cytoplasm (physaliphorous cells) admixed with more epithelioid cells in a myxoid stroma. Parachordomas and chordomas share immunohistochemical and ultrastructural features. Both stain with S-100 protein and vimentin, and ultrastructurally both demonstrate cytoplasmic vacuoles, intermediate filaments, pinocytotic vesicles, celljunctions, and cytoplasmic membranes with microvillous processes. Chordomas more frequently express cytokeratin (98% vs. 66% in parachordomas) and epithelial membrane antigen (90% vs. 20% in parachordomas) and chordomas have a larger number of rough endoplasmic reticulum-mitochondrial complexes. Thus, positive staining with epithelial membrane antigen and the identification of a large number of rough endoplasmic reticulum-mitochondrial complexes are suggestive of metastatic chordoma. However, the definitive distinction remains a clinical one after appropriate radiologic studies of the skull and spinal chord.

Adolescent↗

PubMed2000

The genes encoding granule-bound starch synthases at the waxy loci of the A, B, and D progenitors of common wheat.

Three genes encoding granule-bound starch synthase (wx-TmA, wx-TsB, and wx-TtD) have been isolated from Triticum monococcum (AA), and Triticum speltoides (BB), by the polymerase chain reaction (PCR) approach, and from Triticum tauschii (DD), by screening a genomic DNA library. Multiple sequence alignment indicated that the wx-TmA, wx-TsB, and wx-TtD genes had the same extron and (or) intron structure as the previously reported waxy gene from barley. The lengths of the three wx-TmA, wx-TsB, and wx-TtD genes were 2834 bp, 2826 bp, and 2893 bp, respectively, each covering 31 bp in the untranslated leader and the entire coding region consisting of 11 exons and 10 introns. The three genes had identical lengths of exons, except exonl, and shared over 95% identity with each other within the exon regions. The majority of introns were significantly variable in length and sequence, differing mainly in length (1-57 bp) as a result of insertion and (or) deletion events. The deduced amino acid sequence from these three genes indicated that the mature WX-TMA, -TSB, and -TTD proteins contained the same number of amino acids, but differed in predicted molecular weight and isoelectric point (pI) due to amino acid substitutions (13-18). The predicted physical characteristics of the WX proteins matched the respective proteins in wheat very closely, but the match was not perfect. Furthermore the exon5 sequences of the wx-TmA, wx-TsB, and wx-TtD genes were different from a cDNA encoding a waxy gene of common wheat previously reported. The striking difference was that an insertion of 11 amino acids occurred in the cDNA sequence that could not be observed in the exons of the A, B, and D genes. It was noted, however, that the 3' end of intron4 of these genes could account for the additional 11 amino acids. The sequence information from the available waxy genes identified the intron4-exon5-intron5 region as being diagnostic for sequence variation in waxy. The sequence variation in the waxy genes provides the basis for primer design to distinguish the respective genes in common wheat, and its progenitors, using PCR.

Amino Acid Sequence↗