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At least 1,135 records · Page 63Linked to original sources
PubMed1981

Localization, length and reproduction in single- and multiple-worm infections of Echinostoma revolutum (Trematoda) in the chick.

Mono-metacercarial infections of Echinostoma revolutum in the domestic chick yielded 14- or 15-day-old worms that produced viable eggs, indicating that this species can self-fertilize under conditions which preclude cross-fertilization. In multiple infection studies, chicks were fed either 5 or 10 cysts and each infected chick contained 2-7 worms at necropsy 14 or 15 days later. Worms from multiple infections were mainly paired or clustered and they tended to locate more posteriorly in the intestine than single worms. Length measurements of single and multiple worms were similar. Both the number of eggs and the percentage of hatched eggs were considerably greater in multiple than in single infections.

Animals↗
PubMed1999

Molecular epidemiology of vancomycin-resistant enterococci: a 2-year perspective.

OBJECTIVE: To determine the molecular epidemiology of vancomycin-resistant enterococci (VRE) at our medical center in order to identify the extent of strain clonality and possible transmission patterns of this pathogen. DESIGN: An important facet of our infection control program includes molecular typing of all clinical and surveillance isolates of VRE to determine transmission patterns in the hospital. Molecular strain typing is performed by restriction endonuclease analysis (REA) of genomic DNA. REA patterns are visually compared to categorize VRE strains into type and subtype designations. SETTING: A 588-bed, university-affiliated, tertiary-care hospital and a neighboring 155-bed rehabilitation facility. RESULTS: From January 1995 through December 1996, 379 VRE isolates were collected from 197 patients. Thirty-three genotypes were determined by REA typing; 15 genotypes were implicated in 29 instances of potential nosocomial transmission. Three major clusters of VRE involving patients on multiple nursing units and two adjacent hospitals were identified. The remaining instances of nosocomial transmission occurred in small patient clusters. CONCLUSIONS: In conclusion, the VRE epidemic at this medical center is polyclonal. VRE transmission patterns are complex, and, while large clusters do occur, the usual pattern of nosocomial acquisition of this pathogen occurs in the setting of "mini-clusters".

Bacterial Typing Techniques↗
PubMed1999

[Multiple risk factor syndrome].

Insulin resistance predisposes to the development of a cluster of abnormalities including glucose intolerance, hyperlipidemia, and hypertension, which may relate to the excess intra-abdominal fat deposits. The cluster of abnormalities increases a risk of atherosclerosis and comprises multiple risk factor syndrome (MRFS). Though many suspectable candidate genes of MRFS was analyzed, there is no compelling candidate gene by itself for MRFS. Simultaneous existence of polygenic and environmental factors may induce MRFS resulting in atherosclerosis.

Glucose Intolerance↗
PubMed1998

Associations among multiple geohelminth species infections in schoolchildren from Pemba Island.

In order to estimate the potential benefits of interventions against multiple geohelminth species in endemic areas, an improved understanding of the population biology of multiple infections is required. This paper presents a detailed analysis of the associations among Ascaris lumbricoides, Trichuris trichiura and hookworm infections in 1539 schoolchildren on Pemba Island, Tanzania, where 58% of the sampled children carried infections of all 3 parasites at the time of the study. Infection intensities of different species were positively correlated, and individuals with single-species infections had generally lower species-specific egg counts than individuals with multiple-species infections. There was no age- or sex-related clustering of infections. A weak clustering of intense infections among individuals with multiple-species infections was observed, which became more pronounced as the threshold defining an intense infection increased for each species. The results suggest that individuals with multiple species infections are likely to be at highest risk of geohelminth-related morbidity, not only because of the number of infections they harbour, but also because they generally carry heavier infections of each species.

Animals↗
PubMed2005

Infrared photodissociation spectroscopy of Mg(+)(H2O)Ar(n) complexes: isomers in progressive microsolvation.

Ion-molecule complexes of the form Mg(H2O)Ar(n)+ (n = 1-8) are produced by laser vaporization in a pulsed-nozzle cluster source. These complexes are mass-selected and studied with infrared photodissociation spectroscopy in the O-H stretch region. The spectra are interpreted with the aid of ab initio calculations on the n = 1-5 complexes, including examination of various isomeric structures. The combined spectroscopic and theoretical studies reveal the presence of multiple isomeric structures at each cluster size, as the argon atoms assemble around the Mg(+)(H2O) unit. Distinct infrared resonances are measured for argon-on-metal, argon-on-OH and argon-on-two-OH isomers.

Journal Article↗
PubMed1998

What is beyond the big five?

Previous investigators have proposed that various kinds of person-descriptive content--such as differences in attitudes or values, in sheer evaluation, in attractiveness, or in height and girth--are not adequately captured by the Big Five Model. We report on a rather exhaustive search for reliable sources of Big Five-independent variation in data from person-descriptive adjectives. Fifty-three candidate clusters were developed in a college sample using diverse approaches and sources. In a nonstudent adult sample, clusters were evaluated with respect to a minimax criterion: minimum multiple correlation with factors from Big Five markers and maximum reliability. The most clearly Big Five-independent clusters referred to Height, Girth, Religiousness, Employment Status, Youthfulness and Negative Valence (or low-base-rate attributes). Clusters referring to Fashionableness, Sensuality/Seductiveness, Beauty, Masculinity, Frugality, Humor, Wealth, Prejudice, Folksiness, Cunning, and Luck appeared to be potentially beyond the Big Five, although each of these clusters demonstrated Big Five multiple correlations of .30 to .45, and at least one correlation of .20 and over with a Big Five factor. Of all these content areas, Religiousness, Negative Valence, and the various aspects of Attractiveness were found to be represented by a substantial number of distinct, common adjectives. Results suggest directions for supplementing the Big Five when one wishes to extend variable selection outside the domain of personality traits as conventionally defined.

Female↗
PubMed2006

Binding hot spots in the TEM1-BLIP interface in light of its modular architecture.

Proteins bind one another in aqua's solution to form tight and specific complexes. Previously we have shown that this is achieved through the modular architecture of the interaction network formed by the interface residues, where tight cooperative interactions are found within modules but not between them. Here we extend this study to cover the entire interface of TEM1 beta-lactamase and its protein inhibitor BLIP using an improved method for deriving interaction maps based on REDUCE to add hydrogen atoms and then by evaluating the interactions using modifications of the programs PROBE, NCI and PARE. An extensive mutagenesis study of the interface residues indeed showed that each module is energetically independent on other modules, and that cooperativity is found only within a module. By solving the X-ray structure of two interface mutations affecting two different modules, we demonstrated that protein-protein binding occur via the structural reorganization of the binding modules, either by a "lock and key" or an induced fit mechanism. To explain the cooperativity within a module, we performed multiple-mutant cycle analysis of cluster 2 resulting in a high-resolution energy map of this module. Mutant studies are usually done in reference to alanine, which can be regarded as a deletion of a side-chain. However, from a biological perspective, there is a major interest to understand non-Ala substitutions, as they are most common. Using X-ray crystallography and multiple-mutant cycle analysis we demonstrated the added complexity in understanding non-Ala mutations. Here, a double mutation replacing the wild-type Glu,Tyr to Tyr,Asn on TEM1 (res id 104,105) caused a major backbone structural rearrangement of BLIP, changing the composition of two modules but not of other modules within the interface. This shows the robustness of the modular approach, yet demonstrates the complexity of in silico protein design.

Alanine↗
PubMed1996

Subtypes of incarcerated delinquents constructed via cluster analysis.

The MMPI and Jesness Inventory were used to construct groupings of juvenile delinquents homogeneous with respect to personality characteristics. Subjects were 191 incarcerated juvenile delinquents, aged 12 to 19. All participants had been adjudicated on one or more serious offenses. Five subtypes of delinquents were identified. They included an alienated, unsocialized group, an insecure-anxious group, a group reporting limited difficulties with peers but alienated from adults, a group with no apparent emotional disturbance, and a group with multiple elevations. Significant differences between clusters with regard to self-reported explosiveness, suicidality, gang activities, substance abuse, history of sexual abuse, and delusions and hallucinations were identified. Discriminant function analysis was then used to support the generalizability of the classification system to an independent sample. Eighty per cent of the second sample were accurately classified. The subtypes identified are compared to delinquent classification systems developed previously.

Adult↗
PubMed2004

Chemometric procedure for the study of fractionated wastewater ingredients using RP-HPLC/diode array spectrophotometer.

A fast screening method of domestic wastewater is reported based on fractionation with RP-HPLC and diode array absorption detection implemented by chemometric treatment of the spectra using cluster analysis, deconvolution, simulation, and multiple regression statistical techniques. The proposed method is limited to constituents that absorb in the UV-Vis region which include most of the toxic organic pollutants.

Adsorption↗
PubMed2003

Identification of a novel proline-arginine motif involved in CIN85-dependent clustering of Cbl and down-regulation of epidermal growth factor receptors.

CIN85 is a multidomain adaptor protein implicated in Cbl-mediated down-regulation of receptor tyrosine kinases. CIN85 binding to Cbl is increased after growth factor stimulation and is critical for targeting receptor tyrosine kinases to clathrin-mediated endocytosis. Here we report the identification of a novel polyproline-arginine motif (PXXXPR), specifically recognized by the SH3 domains of CIN85 and its homologue CMS/CD2AP. This motif was indispensable for CIN85 binding to Cbl/Cbl-b, to other CIN85 SH3 domains' effectors, and for mediating an intramolecular interaction between the SH3-A domain and the proline-rich region of CIN85. Individual SH3 domains of CIN85 bound to PXXXPR peptides of Cbl/Cbl-b with micromolar affinities, whereas an extended structure of two or three SH3 domains bound with higher stoichiometry and increased affinity to the same peptides. This enabled full size CIN85 to simultaneously interact with multiple Cbl molecules, promoting their clustering in mammalian cells. The ability of CIN85 to cluster Cbl was important for ligand-induced stabilization of CIN85.Cbl.epidermal growth factor receptor complexes, as well as for epidermal growth factor receptor degradation in the lysosome. Thus, specific interactions of CIN85 SH3 domains with the PXXXPR motif in Cbl play multiple roles in down-regulation of receptor tyrosine kinases.

Adaptor Proteins, Signal Transducing↗
PubMed2003

Single, double, and multiple double strand breaks induced in DNA by 3-100 eV electrons.

Nonthermal secondary electrons with initial kinetic energies below 100 eV are an abundant transient species created in irradiated cells and thermalize within picoseconds through successive multiple energy loss events. Here we show that below 15 eV such low-energy electrons induce single (SSB) and double (DSB) strand breaks in plasmid DNA exclusively via formation and decay of molecular resonances involving DNA components (base, sugar, hydration water, etc.). Furthermore, the strand break quantum yields (per incident electron) due to resonances occur with intensities similar to those that appear between 25 and 100 eV electron energy, where nonresonant mechanisms related to excitation/ionizations/dissociations are shown to dominate the yields, although with some contribution from multiple scattering electron energy loss events. We also present the first measurements of the electron energy dependence of multiple double strand breaks (MDSB) induced in DNA by electrons with energies below 100 eV. Unlike the SSB and DSB yields, which remain relatively constant above 25 eV, the MDSB yields show a strong monotonic increase above 30 eV, however with intensities at least 1 order of magnitude smaller than the combined SSB and DSB yields. The observation of MDSB above 30 eV is attributed to strand break clusters (nano-tracks) involving multiple successive interactions of one single electron at sites that are distant in primary sequence along the DNA double strand, but are in close contact; such regions exist in supercoiled DNA (as well as cellular DNA) where the double helix crosses itself or is in close proximity to another part of the same DNA molecule.

DNA↗
PubMed1998

Heat shock protein 70 family: multiple sequence comparisons, function, and evolution.

The heat shock protein 70 kDa sequences (HSP70) are of great importance as molecular chaperones in protein folding and transport. They are abundant under conditions of cellular stress. They are highly conserved in all domains of life: Archaea, eubacteria, eukaryotes, and organelles (mitochondria, chloroplasts). A multiple alignment of a large collection of these sequences was obtained employing our symmetric-iterative ITERALIGN program (Brocchieri and Karlin 1998). Assessments of conservation are interpreted in evolutionary terms and with respect to functional implications. Many archaeal sequences (methanogens and halophiles) tend to align best with the Gram-positive sequences. These two groups also miss a signature segment [about 25 amino acids (aa) long] present in all other HSP70 species (Gupta and Golding 1993). We observed a second signature sequence of about 4 aa absent from all eukaryotic homologues, significantly aligned in all prokaryotic sequences. Consensus sequences were developed for eight groups [Archaea, Gram-positive, proteobacterial Gram-negative, singular bacteria, mitochondria, plastids, eukaryotic endoplasmic reticulum (ER) isoforms, eukaryotic cytoplasmic isoforms]. All group consensus comparisons tend to summarize better the alignments than do the individual sequence comparisons. The global individual consensus "matches" 87% with the consensus of consensuses sequence. A functional analysis of the global consensus identifies a (new) highly significant mixed charge cluster proximal to the carboxyl terminus of the sequence highlighting the hypercharge run EEDKKRRER (one-letter aa code used). The individual Archaea and Gram-positive sequences contain a corresponding significant mixed charge cluster in the location of the charge cluster of the consensus sequence. In contrast, the four Gram-negative proteobacterial sequences of the alignment do not have a charge cluster (even at the 5% significance level). All eukaryotic HSP70 sequences have the analogous charge cluster. Strikingly, several of the eukaryotic isoforms show multiple mixed charged clusters. These clusters were interpreted with supporting data related to HSP70 activity in facilitating chaperone, transport, and secretion function. We observed that the consensus contains only a single tryptophan residue and a single conserved cysteine. This is interpreted with respect to the target rule for disaggregating misfolded proteins. The mitochondrial HSP70 connections to bacterial HSP70 are analyzed, suggesting a polyphyletic split of Trypanosoma and Leishmania protist mitochondrial (Mt) homologues separated from Mt-animal/fungal/plant homologues. Moreover, the HSP70 sequences from the amitochondrial Entamoeba histolytica and Trichomonas vaginalis species were analyzed. The E. histolytica HSP70 is most similar to the higher eukaryotic cytoplasmic sequences, with significantly weaker alignments to ER sequences and much diminished matching to all eubacterial, mitochondrial, and chloroplast sequences. This appears to be at variance with the hypothesis that E. histolytica rather recently lost its mitochondrial organelle. T. vaginalis contains two HSP70 sequences, one Mt-like and the second similar to eukaryotic cytoplasmic sequences suggesting two diverse origins.

Amino Acid Sequence↗
PubMed2003

Complementary techniques of clustering and composite pattern analysis to Saccharomyces cerevisiae gene expression.

We present the combined application of clustering and composite pattern analysis to Saccharomyces cerevisiae gene expression and sequence data. The aim is to devise a system for the efficient investigation of the upstream regions associated with regulating the coordinated transcriptional response of genes via the location of cis-acting elements. The clustering algorithm presented allows clusters to overlap in light of the fact that many genes are regulated by multiple factors and/or are associated with multiple functions in the organism. The sequence clusters are analysed for shared monad and dyad patterns. These motifs are commonly regarded as putative cis-acting regulatory elements. Computationally, dyad patterns may be difficult and expensive to discover and verify if the sequences are very large. This has highlighted the need to obtain maximally--with regards to the pattern in question--'enriched' sets of sequences to uncover these motifs. We present overlapping clusters as an ideal basis for the discovery of conserved motifs.

Algorithms↗
PubMed1999

Splicing-independent processing of plant box C/D and box H/ACA small nucleolar RNAs.

Small nucleolar RNAs (snoRNAs) are involved in various aspects of ribosome biogenesis and rRNA maturation. Plants have a unique organisation of snoRNA genes where multiple, different genes are tightly clustered at a number of different loci. The maize gene clusters studied here include genes from both of the two major classes of snoRNAs (box C/D and box H/ACA) and are transcribed as a polycistronic pre-snoRNA transcript from an upstream promoter. In contrast to vertebrate and yeast intron-encoded snoRNAs, which are processed from debranched introns by exonuclease activity, the particular organisation of plant snoRNA genes suggests a different mode of expression and processing. Here we show that single and multiple plant snoRNAs can be processed from both non-intronic and intronic transcripts such that processing is splicing-independent and requires endonucleolytic activity. Processing of these different snoRNAs from the same polycistronic transcript suggests that the processing machineries needed by each class are not spatially separated in the nucleolus/nucleus.

Base Sequence↗
PubMed1994

Functional mapping of horizontal connections in developing ferret visual cortex: experiments and modeling.

In cat striate cortex, patchy horizontal axonal projections link columns of similar orientation specificity. To assess the physiological correlates of such clustered projections, a new multisite stimulation technique was used to functionally map the pattern of horizontal synaptic inputs onto single layer 2/3 cells within tangential slices of developing ferret visual cortex. Twenty-four separate sets of horizontal fibers were stimulated within a 1200 microns strip of cortex, while evoked synaptic responses were recorded using whole-cell patch methods. For most cells, input maps demonstrated the presence of clustered horizontal connections in which multiple strong and weak synaptic responses were alternately evoked across the stimulated cortical region. Recordings from up to nine cells in a single slice revealed that patterns of synaptic input were closely correlated for cells in close proximity, and that this correlation decreased with distance, with no correlation at distances greater than 500 microns. To determine whether these physiological results were consistent with the known anatomical linkage of iso-orientation columns by clustered horizontal connections, mathematical analysis and computer simulations were performed upon orientation tuning maps obtained from optical imaging of activity-dependent intrinsic signals in mature ferret visual cortex. Optical imaging revealed an organization of iso-orientation domains consisting of broad regions of cortex across which orientation preference smoothly varied, together with "orientation centers" around which orientation preference was arranged in a pinwheel manner. The distribution of synaptic connections between different cortical sites was simulated by a model of functionally linked iso- orientation columns. Simulated synaptic input maps, generated by the same stimulation and recording arrangements used in our experimental protocol, accurately reproduced the observed patterns of clustered inputs onto experimentally recorded cells. These results indicate that even at the time of eye opening, prior to extensive visual experience, most cells receive patterns of synaptic inputs consistent with a clustered organization of horizontal connections that functionally link iso-orientation columns.

Animals↗
PubMedDate not supplied

Characterization of BOLD activation in multi-echo fMRI data using fuzzy cluster analysis and a comparison with quantitative modeling.

A combination of multiple gradient-echo imaging and exploratory data analysis (EDA), i.e. fuzzy cluster analysis (FCA), is proposed for separation and characterization of BOLD activation in single-shot spiral functional magnetic resonance imaging (fMRI) experiments at 3 T. Differentiation of functional activation using FCA is performed by clustering pixel signal changes (DeltaS) as a function of echo time (TE). Further vascular classification is supported by the localization of activation and the comparison with a single-exponential decay model. In some subjects, an additional indication for large vessels within a voxel was found as oscillation of the fMRI signal difference vs echo time (TE). Such large vessels may be separated from small vessel activation and, therefore, our proposed procedure might prove useful if a more specific functional localization is desired in fMRI. In addition to the signal change DeltaS, DeltaT(2)*/T(2)* is significantly different between activated regions. Averaged over all eight subjects DeltaT(2)* is 1.7 +/- 0.2 ms in ROIs with the highest signal change characterized as containing large vessels, whereas in ROIs corresponding to microvascular environment average DeltaT(2)* values are 0.8 +/- 0.1 ms.

Brain↗
PubMed2003

[Differentiation of closely related and distant human populations by multilocus DNA fingerprinting].

Using multilocus DNA fingerprinting with phage M13 DNA as a probe, we have investigated a heterogeneous group of four human populations from Eastern Europe and Northeastern Asia. These populations belong to two language families: Indo-European (Eastern Slavonic branch: Russians, Belarussians) and Altaian (Turkic branch: Yakuts). The experimental results were treated by different statistical techniques: cluster analysis, multidimensional scaling, and multiple correspondence analysis. Coefficients of genetic differentiation were estimated using similarity indices and heterozygosities. The results of our study demonstrated similarity of Belarussian populations and significant differences between the group of Slavonic populations and Yakuts.

Asian People↗