bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of the Osiris Expert System for Identification of β-Lactam Phenotypes in Isolates of
Pseudomonas aeruginosa
Authors: Bert Frédéric , Ould-Hocine Zahia , Juvin Manette , Dubois Véronique , Loncle-Provot Véronique , Lefranc Valérie , Quentin Claudine , Lambert Nicole , Arlet Guillaume
Published: August 2003

Osiris is a video zone size reader for disk diffusion tests featuring a built-in extended expert system (EES). The efficacy of the EES for the identification of the β-lactam susceptibility phenotypes of
Pseudomonas aeruginosa
isolates was evaluated. Thirteen β-lactams were tested in four laboratories by the disk diffusion test with 53 strains with well-characterized resistance mechanisms, including the production of 12 extended-spectrum β-lactamases (ESBLs). The plates were read with the Osiris system and the results were interpreted with the ESS, and then the phenotype identified by the EES was compared to the resistance mechanism. The strains were also screened for the presence of ESBL production by a double-disk synergy test by placing the strains between an extended-spectrum cephalosporin-containing disk and a clavulanic acid-containing disk at distances of 30, 20, 15, and 10 mm from each other. Overall, the EES accurately identified the phenotypes of 88.2% of the strains and indicated an association with several mechanisms for 3.8% of the strains. No phenotype was identified in four strains with low levels of penicillinase production. Misidentifications were observed for two penicillinase-producing strains: one strain with partially derepressed cephalosporinase production and one strain overexpressing the MexA-MexB-OprM efflux system. The production of only four ESBLs was detected by the standard synergy test with a 30-mm distance between the disks. The production of five further ESBLs was identified by reducing the distance to 20 mm, and the production of the last three ESBLs was detected only at a distance of 15 or 10 mm. Our results indicate that the Osiris EES is an effective tool for the identification of
P. aeruginosa
β-lactam phenotypes. A specific double-disk synergy test with reduced disk distances is necessary for the detection of ESBL production by this organism.
Reproducibility of Positive Test Results in the BDProbeTec ET System for Detection of
Chlamydia trachomatis
and
Neisseria gonorrhoeae
Authors: Culler Elizabeth E. , Caliendo Angela M. , Nolte Frederick S.
Published: August 2003

Nucleic acid amplification tests such as the BDProbeTec ET (BDPT) system are more prone to reproducibility problems than are antigen detection tests and culture. A repeat testing algorithm for all samples with method other than acceleration (MOTA) scores greater than or equal to the cutoff value (2,000) was developed for the BDPT system and applied in a clinical laboratory setting. All positive samples were retested, and if the result of the second test was below the cutoff value, a third test was performed to resolve the discrepancy. Overall, 11 (5.3%) of 207 samples initially positive for
Chlamydia trachomatis
and 11 (10.7%) of 103 samples initially positive for
Neisseria gonorrhoeae
were not confirmed by repeat testing of the original sample. Poor reproducibility was associated with low-positive MOTA scores (2,000 to 9,999) for both analytes. Only 21 (80.8%) of 26 low-positive samples in the
C. trachomatis
test and 4 (33.3%) of 12 low-positive samples in the
N. gonorrhoeae
test retested as positive. The reproducibility of both tests with samples with initial MOTA scores of ≥10,000 increased to 96.7%. The data suggest that retesting of low-positive samples is warranted and could reduce the number of potentially false-positive test results.
Dengue Disease Spectrum among Infants in the 2001 Dengue Epidemic in Chennai, Tamil Nadu, India
Authors: Kabilan L. , Balasubramanian S. , Keshava S. M. , Thenmozhi V. , Sekar G. , Tewari S. C. , Arunachalam N. , Rajendran R. , Satyanarayana K.
Published: August 2003

An investigation in a referral pediatric hospital has indicated that during a recent dengue outbreak in Chennai, Tamil Nadu, India, dengue in infancy constituted 20% of total dengue virus infections with low mortality rates in this hospital. In developing countries, strengthening of dengue management capabilities at hospitals can prevent dengue-related deaths in infants.
Molecular Typing of
Campylobacter jejuni
Isolates Involved in a Neonatal Outbreak Indicates Nosocomial Transmission
Authors: Llovo José , Mateo Estíbaliz , Muñoz Angeles , Urquijo María , On Stephen L. W. , Fernández-Astorga Aurora
Published: August 2003

Genotypic typing by restriction fragment length polymorphism and pulsed-field gel electrophoresis showed that two neonates in a neonatal ward were infected with the same
Campylobacter jejuni
strain. Isolates from the mother and brother of the index patient were identical to each other but distinct from the neonatal type. Genotyping results therefore suggested that the neonatal
C
.
jejuni
infection was nosocomial in origin.
Clinical Impact of a PCR Assay for Identification of
Staphylococcus aureus
and Determination of Methicillin Resistance Directly from Blood Cultures
Authors: Hallin M. , Maes N. , Byl B. , Jacobs F. , De Gheldre Y. , Struelens M. J.
Published: August 2003

We evaluated the clinical usefulness of a PCR assay that discriminates
Staphylococcus aureus
from coagulase-negative staphylococci and detects methicillin resistance on blood cultures by measuring the adaptation of antimicrobial therapy based on the PCR results. Only 7 of 28 patients (25%) benefited from a modification of antibiotic therapy based on the PCR results, since empirical therapy was appropriate in a majority of cases.
Hymenolepis diminuta
Infection in a Child Living in the Urban Area of Rome, Italy
Authors: Marangi Massimo , Zechini Barbara , Fileti Angelica , Quaranta Giorgio , Aceti Antonio
Published: August 2003

We report a case of
Hymenolepis diminuta
infection in an Italian child affected by tuberous sclerosis. Praziquantel is the drug of choice for the treatment of
H. diminuta
infection. However, considering the patient's neurological disease, we decided to use not praziquantel but niclosamide, which proved equally effective.
A new karyological variant of Oecomys (Rodentia: Sigmodontinae) and its phylogenetic relationship based on molecular data
Authors: Belchior de Andrade Ana Flávia , Bonvicino Cibele Rodrigues
Published: August 2003

A new karyological variant of the Sigmodontinae genus Oecomys was detected in specimens from Brazilian Pantanal. Karyologic analyses showed 2n = 72 and FN = 90, which differs from all known chromosomal complements of the genus. This new karyomorph showed distinctive morphological attributes and could not be attributed to any described Oecomys species. Molecular analysis using cytochrome-b sequence data suggested the monophyly of Oecomys. Maximum-likelihood analyses placed the Oecomys sp. haplotype clade as the sister branch to Oecomys bicolor, whereas maximum-parsimony analyses did not resolve its relationship with the other Oecomys species. Kimura's two parameters distance estimates between this and other Oecomys species are high, and active gene flow has been found not to coexist with these divergence estimates.Key words: Oecomys sp., rodent, Sigmodontinae, karyotype, molecular phylogeny.
The organization of genes tightly linked to the Ha locus in Aegilops tauschii, the D-genome donor to wheat
Authors: Turnbull K -M , Turner M , Mukai Y , Yamamoto M , Morell M K , Appels R , Rahman S
Published: August 2003

The grain hardness locus, Ha, is located at the distal end of the short arm of chromosome 5D in wheat. Three polypeptides, puroindoline-a, puroindoline-b, and grain softness protein (GSP-1), have been identified as components of friabilin, a biochemical marker for grain softness, and the genes for these polypeptides are known to be tightly linked to the Ha locus. However, this region of the chromosome 5D has not been well characterized and the physical distance between the markers is not known. Separate lambda clones containing the puroindoline-a gene and the puroindoline-b gene have been isolated from an Aegilops tauschii (the donor of the D genome to wheat) genomic lambda library and investigated. Considerable variation appears to exist in the organization of the region upstream of the gene for puroindoline-b among species closely related to wheat. Using in situ hybridization the genes for puroindoline-a, -b, and GSP-1 were demonstrated to be physically located at the tip of the short arm of chromosome 5 of A. tauschii. Four overlapping clones were isolated from a large-insert BAC library constructed from A. tauschii and of these one contained genes for all of puroindoline-a, puroindoline-b, and GSP-1. The gene for puroindoline-a is located between the other two genes at a distance no greater than approximately 30 kb from either gene. The BAC clone containing all three known genes was used to screen a cDNA library constructed from hexaploid wheat and cDNAs that could encode novel polypeptides were isolated.Key words: puroindolines, GSP-1, chromosome 5D, BAC library, tauschii.
Comparison of peach and Arabidopsis genomic sequences: fragmentary conservation of gene neighborhoods
Authors: Georgi Laura L , Wang Ying , Reighard Gregory L , Mao Long , Wing Rod A , Abbott Albert G
Published: August 2003

We examined the degree of conservation of gene order in two plant species, Prunus persica (peach) and Arabidopsis thaliana (thale cress), whose lineages diverged more than 90 million years ago. In the three peach genomic regions studied, segments with a gene order congruent with A. thaliana were short (two to three genes in length); and for any peach region, corresponding segments were found in diverse locations in the A. thaliana genome. At the gene level and lower, the A. thaliana sequence was enormously useful for identifying likely coding regions in peach sequences and in determining their intronexon structure. The peach BAC sequence data reported here contained a BLAST-detectable putative coding sequence an average of every 7 kb, and the peach introns identified in this study were, on average, almost twice the length of the corresponding introns in A. thaliana.Key words: conserved microsynteny, genome evolution.
Segmental allotetraploidy and allelic interactions in buffelgrass (Pennisetum ciliare(L.) Link syn.Cenchrus ciliarisL.) as revealed by genome mapping
Authors: Jessup R W , Burson B L , Burow G , Wang Y -W , Chang C , Li Z , Paterson A H , Hussey M A
Published: August 2003

Linkage analyses increasingly complement cytological and traditional plant breeding techniques by providing valuable information regarding genome organization and transmission genetics of complex polyploid species. This study reports a genome map of buffelgrass (Pennisetum ciliare (L.) Link syn. Cenchrus ciliaris L.). Maternal and paternal maps were constructed with restriction fragment length polymorphisms (RFLPs) segregating in 87 F1progeny from an intraspecific cross between two heterozygous genotypes. A survey of 862 heterologous cDNAs and gDNAs from across the Poaceae, as well as 443 buffelgrass cDNAs, yielded 100 and 360 polymorphic probes, respectively. The maternal map included 322 RFLPs, 47 linkage groups, and 3464 cM, whereas the paternal map contained 245 RFLPs, 42 linkage groups, and 2757 cM. Approximately 70 to 80% of the buffelgrass genome was covered, and the average marker spacing was 10.8 and 11.3 cM on the respective maps. Preferential pairing was indicated between many linkage groups, which supports cytological reports that buffelgrass is a segmental allotetraploid. More preferential pairing (disomy) was found in the maternal than paternal parent across linkage groups (55 vs. 38%) and loci (48 vs. 15%). Comparison of interval lengths in 15 allelic bridges indicated significantly less meiotic recombination in paternal gametes. Allelic interactions were detected in four regions of the maternal map and were absent in the paternal map.Key words: linkage map, segmental allopolyploidy, restriction fragment length polymorphism, Poaceae, chromosome pairing.
Chromosomal mapping of 18S28S and 5S rRNA genes by two-colour fluorescent in situ hybridization in six sturgeon species
Authors: Fontana Francesco , Lanfredi Massimo , Congiu Leonardo , Leis Marilena , Chicca Milvia , Rossi Remigio
Published: August 2003

The number and distribution of the 18S28S and 5S rRNA (rDNA) gene sequences were examined on mitotic chromosomes of six sturgeon species by two-colour in situ hybridization. Four of the six species, Huso huso, Acipenser stellatus, Acipenser sturio, and Acipenser ruthenus, with about 120 chromosomes, showed from six to eight 18S28S rDNA signals, while 5S rDNA signals were on only one chromosome pair. The two species with 250270 chromosomes, Acipenser baerii and Acipenser transmontanus, showed from 10 to 12 18S28S sites and two chromosome pairs bearing 5S rDNA signals. In all examined species, the rather intense 5S rDNA signals apparently overlapped those of 18S28S rDNA. These data support the diploidtetraploid relationships between the two chromosome groups of sturgeons. The close association between the two rDNA families in species belonging to an ancestral fish order, such as Acipenseriformes, supports the hypothesis that the association represents a primitive condition.Key words: Acipenseriformes, FISH, fish cytogenetics, ribosomal genes.
Construction of a garlic BAC library and chromosomal assignment of BAC clones using the FISH technique
Authors: Lee Hye-Ran , Eom Eun-Mi , Lim Yong-Pyo , Bang Jae-Wook , Lee Dong-Hee
Published: August 2003

For molecular and cytogenetic studies, two partial bacterial artificial chromosome (BAC) libraries of the garlic cultivar Allium sativum L. 'Danyang' were constructed using high molecular weight (HMW) garlic DNA, the pBAC1SACB1 vector, and the pIndigoBAC536 vector. The average insert size of the BAC library was about 90 kb. The sequence compositions of the BAC clones were characterized by Southern hybridization with garlic genomic DNA and a repetitive sequence clone of garlic. Two BAC clones with weak signals (thus implying mostly unique sequences), GBC2-5e and GBC2-4d, were selected for FISH analysis. FISH analysis localized the GBC2-5e (~100 kb) BAC clone on the long arm of garlic chromosome 7. The other BAC clone, GBC2-4d (~110 kb), gave rise to discrete FISH signals on a mid-size early metaphase chromosome. The FISH screening with BAC clones proved to be a useful resource for molecular cytogenetic studies of garlic, and will be useful for further mapping and sequencing studies of important genes of this plant.Key words: garlic, chromosomal assignment, Allium sativum L., FISH technique, BAC library.
Molecular mapping of novel genes controllingFusariumhead blight resistance and deoxynivalenol accumulation in spring wheat
Authors: Somers Daryl J , Fedak George , Savard Marc
Published: August 2003

Fusarium head blight of wheat is an extremely damaging disease, causing severe losses in seed yield and quality. The objective of the current study was to examine and characterize alternate sources of resistance to Fusarium head blight (FHB). Ninety-one F1-derived doubled haploid lines from the cross Triticum aestivum 'Wuhan-1' × Triticum aestivum 'Maringa' were examined for disease reaction to Fusarium graminearum by single-floret injection in replicated greenhouse trials and by spray inoculation in replicated field trials. Field and greenhouse experiments were also used to collect agronomic and spike morphology characteristics. Seed samples from field plots were used for deoxynivalenol (DON) determination. A total of 328 polymorphic microsatellite loci were used to construct a genetic linkage map in this population and together these data were used to identify QTL controlling FHB resistance, accumulation of DON, and agronomic and spike morphology traits. The analysis identified QTL for different types of FHB resistance in four intervals on chromosomes 2DL, 3BS, and 4B. The QTLs on 4B and 3BS proximal to the centromere are novel and not reported elsewhere. QTL controlling accumulation of DON independent of FHB resistance were located on chromosomes 2DS and 5AS. Lines carrying FHB resistance alleles on 2DL and 3BS showed a 32% decrease in disease spread after single-floret injection. Lines carrying FHB resistance alleles on 3BS and 4B showed a 27% decrease from the mean in field infection. Finally, lines carrying favourable alleles on 3BS and 5AS, showed a 17% reduction in DON accumulation. The results support a polygenic and quantitative mode of inheritance and report novel FHB resistance loci. The data also suggest that resistance to FHB infection and DON accumulation may be controlled, in part, by independent loci and (or) genes.Key words: marker-assisted selection, Fusarium, wheat, microsatellite.
A single point mutation inDrosophiladihydrofolate reductaseconfers methotrexate resistance to a transgenic CHO cell line
Authors: Neumann K , Al-Batayneh K M , Kuiper M J , Parsons-Sheldrake J , Tyshenko M G , Flintoff W F , Cole S P.C , Walker V K
Published: August 2003

Sequence analysis of a cDNA encoding dihydrofolate reductase (DHFR) from a selected methotrexate-resistant Drosophila melanogaster cell line (S3MTX) revealed a substitution of Gln for Leu at position 30. Although the S3MTXcells were ~1000 fold more resistant to methotrexate (MTX), the karyotype was similar to the parental line and did not show elongated chromosomes. Furthermore, kinetic analysis of the recombinant enzyme showed a decreased affinity for MTX by the mutant DHFR. To determine if the resistance phenotype could be attributed to the mutant allele, Drosophila Dhfr cDNAs isolated from wild type and S3MTXcells were expressed in Chinese hamster ovary (CHO) cells lacking endogenous DHFR. The heterologous insect DHFRs were functional in transgenic clonal cell lines, showing ~400-fold greater MTX resistance in the cell line transfected with the mutant Dhfr than the wild type Dhfr. Resistance to other antifolates in the CHO cells was consistent with the drug sensitivities seen in the respective Drosophila cell lines. ELevated Levels of Dhfr transcript and DHFR in transgenic CHO cells bearing the mutant cDNA were not seen. Taken together, these results demonstrate that a single substitution in Drosophila DHFR alone can confer Levels of MTX resistance comparable with that observed after considerable gene amplification in mammalian cells.Key words: dihydrofolate reductase, methotrexate, drug resistance, point mutation.
Soybean seed lustre phenotype and surface protein cosegregate and map to linkage group E
Authors: Gijzen Mark , Weng Changren , Kuflu Kuflom , Woodrow Lorna , Yu Kangfu , Poysa Vaino
Published: August 2003

Soybean (Glycine max (L.) Merr.) seeds vary in their surface properties. The lustre, or glossiness, of seeds has been classified into several different phenotypes. Soybean seeds that have a dull lustre or moderate bloom (B) may also have abundant seed surface protein, namely, an abundance of the hydrophobic protein from soybean (HPS). The seed surface protein HPS is an allergen (Gly m 1) that causes asthma in persons allergic to soybean dust. In this study, seed lustre and surface protein content are compared among 71 different soybean cultivars and lines. Dull-seeded phenotypes usually possessed abundant surface protein in comparison to shiny-seeded types, although exceptions were observed. An F2population of 82 individuals from a cross of OX281 (dull lustre, abundant HPS) and Mukden (shiny lustre, trace amounts of HPS) provided a basis for inheritance studies and genetic mapping analysis. Results indicate that dull seed lustre (B) and surface protein (Hps) loci are dominant Mendelian traits that cosegregate and map to soybean linkage group E. Molecular markers were used to construct a genetic map of 28 cM encompassing B and Hps. Two different molecular markers cosegregated with each of the loci. This study provides additional evidence that Hps may play a role in the adhesion of endocarp tissues to the seed, and offers new methods of selection for seed lustre and surface protein composition in soybean.Key words: adhesion, allergen, hydrophobic protein, pericarp, seed coat.
Motor Cortex Stimulation in the Treatment of Deafferentation Pain. I. Localization of the Motor Cortex1
Authors: Velasco Marcos , Velasco Francisco , Brito Francisco , Velasco Ana Luisa , Nguyen Jean Paul , Marquez Irma , Boleaga Bernardo , Keravel Yves
Published: August 2003

MRI and electrophysiological techniques to localize the primary motor cortex (MC) were performed on patients considered for MC stimulation for the treatment of deafferentation pain. The representation and trajectory of the rolandic fissure (RF) were accurately localized by external cranial landmarks and radiopaque fiducials superimposed on oblique MRI sections. In addition, the scalp distribution of the corticocortical responses elicited by acute epidural stimulation [motor cortex (MC) in frontal and sensory cortex (SC) in parietal scalp regions], and analgesic responses at the topographical representation of the painful periphery elicited by subacute epidural stimulation were found to be simple and reliable procedures to localize MC, SC and RF.
Technical Difficulties and Perioperative Complications of Retrogasserian Glycerol Rhizotomy for Trigeminal Neuralgia
Authors: Blomstedt Patric C. , Bergenheim A. Tommy
Published: August 2003

In 139 patients, 260 consecutive retrogasserian glycerol rhizotomies for trigeminal neuralgia were retrospectively analyzed regarding technical surgical difficulties and immediate and early complications. Technical obstacles occurred in 47.3%. In 21 cases (8.1%), the surgical procedure had to be interrupted due to circumstances such as vasovagal reactions, cardiac arrest, or difficulties to find the trigeminal cistern. Complications or side effects, being either transient or persistent, occurred in 67.3%. In the vast majority, those unwanted effects were related to mild sensory deficits. However, in 28.1% the complications were other than mild affection of facial sensibility. These slightly graver complications included labial herpes (3.8%), anesthesia dolorosa (0.8%), moderate or severe affection of sensibility (18.8%), dysesthesia (22.7%), chemical meningitis (1.5%) and infectious meningitis (1.5%). In 5 patients (1.9%) hearing was affected. In one of them, this condition was also brought about by tinnitus, and in another patient a preexisting tinnitus deteriorated. Although the frequency of surgical difficulties was high, the success of the glycerol injection was hampered only in a minor number of procedures. The frequency of complications and side effects was high, but they were mostly mild due to their nature and non-disabling for the patient. However, long-lasting disabling side effects occurred, and this should not be neglected when informing patients preoperatively. The surgical training needed to perform the procedure is stressed, and the use of prophylactic antibiotics when accidentally penetrating the oral bucca is recommended. We consider retrogasserian glycerol rhizotomy to be a good surgical option for patients with trigeminal neuralgia not suitable for microvascular decompression and when pharmacological therapy is not sufficient or is not tolerated.
Interventional MRI-Guided Frameless Stereotaxy in Pediatric Patients
Authors: Vitaz Todd W. , Hushek Stephen G. , Shields Christopher B. , Moriarty Thomas M.
Published: August 2003

Introduction: We prospectively reviewed our experience with intraoperative MRI (iMRI)-guided stereotactic procedures in pediatric patients. Methods: All procedures were performed within the magnet bore of the General Electric Signa SP MRI system, which allows for either continuous real-time or periodic imaging. The internal optical tracking system was used to plan and monitor target localization and instrument trajectory. Results: Fifteen patients underwent 16 frameless stereotactic procedures, consisting of 4 tumor biopsies and 12 cyst aspirations and stereotactic catheter placements (average age 6 years, range 6 weeks to 18 years). There were no hemorrhagic, neurologic or infectious complications. Conclusion: iMRI is an important component in expanding the horizon of minimally invasive neurosurgery for pediatric patients. Thus far, we have found this technology to be safe, reliable and extremely useful for frameless stereotactic procedures.
Computed Tomographic Parameters Predicting Fatal Outcome in Large Middle Cerebral Artery Infarction
Authors: Barber Philip A. , Demchuk Andrew M. , Zhang Jinjin , Kasner Scott E. , Hill Michael D. , Berrouschot Jorg , Schmutzhard Erich , Harms Lutz , Verro Piero , Krieger Derk
Published: August 2003

Background: Large middle cerebral artery (MCA) ischaemic stroke when associated with extensive mass effect can result in brain herniation and neurological death. As yet there are few guidelines to aid the selection of patients for aggressive interventional therapies, such as decompression hemicraniectomy and/or hypothermia. Methods: We studied a cohort of patients from seven centres with large MCA infarction requiring neurocritical care. The purpose of this analysis was to assess the use of early radiological signs on follow-up computed tomographic (CT) signs performed within 48 h of stroke onset for predicting mortality at 30 days. The CT parameters assessed included horizontal displacement of the septum pellucidum, pineal shift, complete or partial infarction of the temporal lobe, involvement of additional vascular territories, and the presence of hydrocephalus. The primary outcome measure was in-hospital death within 30 days. Results: One hundred and thirty-five patients who had follow-up CT scans within 48 h were identified from a total of 201 patients with large MCA infarction that received conventional medical therapy alone. The median age was 68 (range 29–99), 56% were female, and the median NIHSS category was 26–30 at 48 h. Among CT variables in univariable analysis, anteroseptal shift ≧5 mm, pineal shift ≧2 mm, complete temporal lobe infarction, involvement beyond the MCA territory, and moderate or severe hydrocephalus were equally predictive of death. Multivariable analysis adjusting for time to CT scan revealed the following predictors of fatal outcome: anteroseptal shift ≧5 mm (OR 10.9; 95% CI 3.2–37.6), NIHSS within 48 h >20 (OR 6.6; 95% CI 2.3–19.3), and infarction beyond the MCA territory (OR 4.9; 95% CI 1.6–15.0). Conclusions: We identified the role of early CT signs in predicting death following massive MCA infarction. The CT parameters anteroseptal shift (>5 versus ≤5 mm), pineal shift ≧2 mm, hydrocephalus, temporal lobe infarction, and other vascular territory infarction if present were predictive of fatal outcome. These CT parameters require prospective validation before they should be considered reliable markers for decision-making.
A Canadian Cohort Study of Cognitive Impairment and Related Dementias (ACCORD): Study Methods and Baseline Results
Authors: Feldman H. , Levy A.R. , Hsiung G.-Y. , Peters K.R. , Donald A. , Black S.E. , Bouchard R.W. , Gauthier S.G. , Guzman D.A. , Hogan D.B. , Kertesz A. , Rockwood K.
Published: August 2003

The overall objective of the Canadian Collaborative Cohort of Related Dementias (ACCORD) study is to describe the diagnostic distribution, natural history and treatment outcomes of individuals referred from the community to dementia clinics in Canada. Between 1997 and 1999, an inception cohort of 1,136 subjects entered into this longitudinal study. At the baseline assessment, 10.9% of the subjects were classified as ‘not cognitively impaired’ (NCI), 30.1% as ‘cognitively impaired not demented’ (CIND), and 59% as demented. A subclassification of CIND included amnestic 25.1%, vascular cognitive impairment 18.1%, psychiatric 17.2%, neurologic 7.3%, medical/toxic metabolic 3.5%, mixed 7.6% and not specified 19.0%. The percentage of the cohort referred with dementia increased progressively each decade, while the proportions of CIND and NCI decreased. Within the dementia group, Alzheimer’s disease accounted for 47.2% of the subjects, mixed dementias 33.7%, vascular dementia 8.7%, frontotemporal degenerations 5.4%, dementia with Lewy bodies 2.5%, and unclassifiable 1.8%. The ACCORD cohort will allow a detailed study of the longitudinal course of CIND, and the longer-term outcomes of both treated and untreated dementia subjects.
X chromosome inactivation: how human are mice?
Authors: Vasques L.R. , Klöckner M.N. , Pereira L.V.
Published: August 2003

Mammals perform dosage compensation of X-linked gene products between XY males and XX females by transcriptionally silencing all but one X chromosome per diploid cell, a process called X chromosome inactivation (XCI). XCI involves counting X chromosomes in a cell, random or imprinted choice of one X to remain active, initiation and spread of the inactivation signal in cis throughout the other X chromosomes, and maintenance of the inactive state of those X chromosomes during cell divisions thereafter. Most of what is known of the molecular mechanisms involved in the different steps of XCI has been studied in the mouse. In this review we compare XCI in mouse and human, and discuss how much of the murine data can be extrapolated to humans.
Nonrandom X chromosome inactivation in mouse embryos carrying Searle’s T(X;16)16H translocation visualized using X-linked lacZ and GFP transgenes
Authors: Takagi N. , Sugimoto M. , Yamaguchi S. , Ito M. , Tan S.-S. , Okabe M.
Published: August 2003

Only the morphologically normal X chromosome is inactivated in female mice heterozygous for Searle’s X-autosome translocation, T(X;16)16H. Here we performed a visual study of the primary and secondary events that culminate in the completely nonrandom inactivation of the X in female embryos having this translocation. The data we have obtained so far indicate that the initial choice of the future inactive X chromosome is biased, with the degree of skewing somewhere between 70:30% and 90:10% in favor of the morphologically normal X chromosome. The majority of genetically unbalanced cells that inactivate a translocated X chromosome are quickly eliminated from the embryo proper by E8.5, although the survival of such cells is sporadically observed thereafter. The initial nonrandom choice demonstrated in this study supports the contention that the T(X;16)16H translocation disrupts one of the loci involved in the randomness of the choice of the future inactive X chromosome. Although the HMG-lacZ transgene in H253 stock mice is an excellent marker of X chromosome inactivation, the present study suggests that it is infrequently de-repressed on the inactive X chromosome.
Antisense regulation in X inactivation and autosomal imprinting
Authors: Ogawa Y. , Lee J.T.
Published: August 2003

The regulation of epigenetic phenomena by elements encoding antisense RNA’s is one of the most rapidly emerging themes in mammalian gene expression. Such regulation is epitomized by X chromosome inactivation (XCI) and autosomal imprinting. In XCI, Tsix serves as an antisense regulator of Xist, the silencer element for XCI which itself makes a non-coding transcript. Numerous antisense transcripts have also been discovered in autosomally imprinted loci, including the Igf2r/Air locus, the Prader-Willi/Angelman Syndrome (PWS/AS) locus, and the Beckwith-Wiedemann Syndrome (BWS) locus. How these antisense elements regulate XCI and imprinting remains unsolved. However, various structural and functional similarities among them imply the possibility of shared mechanism. Among the most interesting are the antagonistic relationship between sense and antisense loci and the initiation of antisense transcripts within imprinting centers. This article reviews the latest developments in antisense regulation in XCI and autosomal imprinting and speculates on molecular means by which antisense genes can regulate silencing in mammals.
Differential patterns of histone methylation and acetylation distinguish active and repressed alleles at X-linked genes
Authors: Goto Y. , Gomez M. , Brockdorff N. , Feil R.
Published: August 2003

In female mammals, one of the two X chromosomes is inactivated to compensate for the difference in dosage of X-linked genes between males and females. X inactivation involves sequential alterations to the chromatin that ultimately lead to the transcriptional repression of genes on the X chromosome. Here, histone methylation and acetylation along X-linked genes are investigated by chromatin immunoprecipitation (ChIP) of adult fibroblast cell lines. At Pgk1 and Hprt, chromatin on the active X chromosome reveals H3 lysine 4 methylation and acetylation of histones H3 and H4. These modifications are absent on the repressed allele, which is marked by H3 lysine 9 methylation. On the expressed allele of Xist (on the inactive X chromosome), we found that H3 acetylation is confined to the promoter, whereas H3 lysine 4 methylation and H4 acetylation are present along the entire gene. On the repressed Xist allele, in contrast, the promoter and gene exhibit H3 lysine 9 methylation. At only 1.5 kb upstream of the Xist gene, chromatin on the inactive X chromosome has strongly reduced levels of H4 acetylation and is marked by both H3 lysine 9 and H3 lysine 4 methylation. These data demonstrate that patterns of histone methylation and acetylation are distinct along and upstream of Xist and suggest that the inactive X chromatin configuration occurs at a region close to the 5′ end of the gene.
The Azoospermia region AZFa: An evolutionar y view
Authors: Wimmer R. , Kirsch S. , Weber A. , Rappold G.A. , Schempp W.
Published: August 2003

Compared to other regions on the human Y chromosome, the genomic segment encompassing the functionally defined AZFa locus has undergone higher X–Y sequence divergence, which is detectable by fluorescence in-situ hybridisation. This allows an evolutionary definition of an interval enclosing AZFa with a size of about 1.1 Mb. The region includes the genes USP9Y, DBY and UTY and is limited by evolutionary breakpoints within the PAC clones 41L06 and 46M11. These breakpoints restrict an area of possible male specific evolution that may have resulted in the acquisition of male specific functions, including a role in spermatogenesis.
Reorganization of the X chromosome in voles of the genus Microtus
Authors: Rubtsov N.B. , Rubtsova N.V. , Anopriyenko O.V. , Karamysheva T.V. , Shevchenko A.I. , Mazurok N.A. , Nesterova T.B. , Zakian S.M.
Published: August 2003

Comparative chromosomal analysis is a powerful tool in the investigation of the mechanisms of chromosomal evolution. The accuracy of the analysis depends on the availability of region-specific markers to follow the fate of the particular chromosomal region through the evolution of species. We have assigned 12 unique sequences to the euchromatic part of the vole X chromosome, which serve as reliable markers of chromosomal segments. Together with region-specific libraries and GTG banding, these markers allow us to delineate the homologous regions of the X chromosomes in five species of the genus Microtus. We found that X chromosomes of these species differ by numerous rearrangements and all rearrangements are clustered at specific breakpoints. Moreover, these breakpoints were found to colocalise with repetitive and/or duplicated DNA sequences. We suggest that clusters of repeated and/or duplicated DNA sequences have played a crucial role in the formation of rearrangement hot spots during evolution of the X chromosome in the subgenus Microtus.
Mapping Quantitative Trait Loci Using Multiple Phenotypes in General Pedigrees
Authors: Wang Kai
Published: August 2003

The use of correlated phenotypes may dramatically increase the power to detect the underlying quantitative trait loci (QTLs). Current approaches for multiple phenotypes include regression-based methods, the multivariate variance of components method, factor analysis and structural equations. Issues with these methods include: 1) They are computation intensive and are subject to problems of optimization algorithms; 2) Existing claims on the asymptotic distribution of the likelihood ratio statistic for the multivariate variance of components method are contradictory and erroneous; 3) The dimension reduction of the parameter space under the null hypothesis, a phenomenon that is unique to multivariate analyses, makes the asymptotic distribution of the likelihood ratio statistic more complicated than expected. In this article, three cases of varying complexity are considered. For each case, the efficient score statistic, which is asymptotically equivalent to the likelihood ratio statistic, is derived, so is its asymptotic distribution. These methods are straightforward to calculate. Finite-sample properties of these score statistics are studied through extensive simulations. These score statistics are for use with general pedigrees.
Number of SNPS Loci Needed to Detect Population Structure
Authors: Turakulov Rust , Easteal Simon
Published: August 2003

The study of the association of polymorphic genetic markers with common diseases is one of the most powerful tools in modern genetics. Interest in single nucleotide polymorphisms (SNPs) has steadily grown over the last decade. SNPs are currently the most developed markers in the human genome because they have a number of advantages over other marker types. One of the critical problems responsible for ‘spurious’ association findings in case-control studies is population stratification. There are many statistical approaches developed for detecting population heterogeneity. However the power to detect population structure by known methods is highly dependent on the number of loci utilised. We performed an analysis of SNPs data available in the public domain from The Single Nucleotide Consortia Ltd. (TSCL). Three populations, Afro-American, Asian and Caucasian, were compared. Estimation of the minimum number of SNPs loci necessary for detection of the population structure was performed. Two clustering approaches, distance-based and model-based, were compared. The model-based approach was superior when compared with the distance-based method. We found more than 65 random SNPs loci are required for identifying distinct geographically separated populations. Increasing the number of markers to over 100 raises the probability of correct assignment of a particular individual to an origin group to over 90%, even with conventional clustering methods.
Estimation and Tests of Haplotype-Environment Interaction when Linkage Phase Is Ambiguous
Authors: Lake S.L. , Lyon H. , Tantisira K. , Silverman E.K. , Weiss S.T. , Laird N.M. , Schaid D.J.
Published: August 2003

In the study of complex traits, the utility of linkage analysis and single marker association tests can be limited for researchers attempting to elucidate the complex interplay between a gene and environmental covariates. For these purposes, tests of gene-environment interactions are needed. In addition, recent studies have indicated that haplotypes, which are specific combinations of nucleotides on the same chromosome, may be more suitable as the unit of analysis for statistical tests than single genetic markers. The difficulty with this approach is that, in standard laboratory genotyping, haplotypes are often not directly observable. Instead, unphased marker phenotypes are collected. In this article, we present a method for estimating and testing haplotype-environment interactions when linkage phase is potentially ambiguous. The method builds on the work of Schaid et al. [2002] and is applicable to any trait that can be placed in the generalized linear model framework. Simulations were run to illustrate the salient features of the method. In addition, the method was used to test for haplotype-smoking exposure interaction with data from the Childhood Asthma Management Program.
Vessel- and Vasoconstrictor-Dependent Role of Rho/Rho-Kinase in Renal Microvascular Tone
Authors: Nakamura Akira , Hayashi Koichi , Ozawa Yuri , Fujiwara Keiji , Okubo Ken , Kanda Takeshi , Wakino Shu , Saruta Takao
Published: August 2003

We examined the role of Rho/Rho-kinase in renal afferent and efferent arteriolar tone induced by angiotensin (Ang) II, KCl and elevated renal arterial pressure (from 80 to 180 mm Hg), using isolated perfused rat hydronephrotic kidney. In the condition with no vasoconstrictor stimuli, Y-27632, a Rho-kinase inhibitor, dilated only afferent (from 11.6 ± 0.4 to 14.1 ± 0.5 µm) but not efferent arterioles (from 11.6 ± 0.2 to 12.6 ± 0.7 µm) at 10–5 mol/l. During renal vasoconstriction by Ang II, Y-27632 restored the afferent arteriolar constriction (141 ± 10% reversal at 10–5 mol/l), whereas the ability of Y-27632 to inhibit the Ang II-induced efferent arteriolar constriction was diminished (73 ± 7% reversal). A similar action was observed with fasudil, another Rho-kinase inhibitor. Furthermore, Y-27632 impaired myogenic afferent arteriolar constriction, with 117 ± 17% inhibition at 10–5 mol/l. The inhibition by Y-27632 of the myogenic vasoconstriction was almost the same as that of the Ang II-induced tone of this vessel type. However, Y-27632 had a modest effect on KCl-induced vasoconstriction of afferent arterioles. In conclusion, the present study demonstrates a predominant role of Rho/Rho-kinase in mediating the basal and Ang II-induced tone of afferent, but not efferent, arterioles. Furthermore, the role of Rho/Rho-kinase in afferent arteriolar constriction differs, with a substantial contribution to Ang II-induced and myogenic constriction but a minimal role in depolarization-induced constriction. Since Ang II-induced, KCl-induced and myogenic constriction of afferent arterioles require calcium entry through voltage-dependent calcium channels, the interaction between Rho/Rho-kinase and the calcium entry pathway may determine the afferent arteriolar tone induced by these stimuli.
Effects of an Angiotensin II Receptor Antagonist and Angiotensin-Converting Enzyme Inhibitors on Burst Forming Units-Erythroid in Chronic Hemodialysis Patients
Authors: Naito Masayo , Kawashima Akira , Akiba Takashi , Takanashi Minoko , Nihei Hiroshi
Published: August 2003

Background: Angiotensin-converting enzyme (ACE) inhibitors have been reported to reduce the response to erythropoietin (EPO) administration in chronic hemodialysis patients, but the mechanism for this effect has not yet been clarified. To clarify the mechanism of ACE inhibitors- and angiotensin II type 1 (AT1) receptor antagonist-induced anemia in hemodialysis patients, we examined the effect of ACE inhibitors and AT1 receptor antagonist on burst-forming units-erythroid (BFU-E) in the peripheral blood of hemodialysis patients and healthy controls in vitro. Methods: Peripheral blood mononuclear cells (PBMNCs) were isolated by gradient centrifugation from 10 patients on regular hemodialysis and 7 healthy control volunteers. A colony assay of hematopoietic progenitors was performed using the methylcellulose culture system. PBMNCs of 1 or 2 × 105 were plated in a medium containing EPO with various concentrations of ACE inhibitors or AT1 receptor antagonist and incubated for 14 days. Colonies of BFU-E were counted under an inverted microscope. Results: The PBMNCs from the chronic hemodialysis patients formed fewer BFU-Es than those from healthy volunteers. AT1 receptor antagonist in both healthy volunteers and hemodialysis patients suppressed the number of BFU-Es. The ACE inhibitors produced a smaller effect than the AT1 receptor antagonist. Conclusion: AT1 receptor blockade can directly inhibit erythropoiesis in vitro.
Does Money Make a Difference for Hispanic Students in Urban Schools?
Authors: Reyes Augustina H.
Published: August 2003

Six teacher preparation categories—long-term substitutes, temporary teaching permit, certified in a field different from the assigned teaching subject, alternative certification, full certification in the assigned teaching subject, and certification unknown—are studied as a significant component within the flow of resources for their effect on student achievement at a single high-poverty campus. There were no statistically significant differences in national curve equivalence (NCE) scores among students taught by teachers with full certification, alternative certification, or math temporary teaching permits on end-of the-semester math grades. At-risk students taught reading by teachers with alternative certification scored significantly higher than at-risk students taught reading by teachers with full certification.
Simulation Modelling and Analysis of a Port Investment
Authors: Demirci Emrullah
Published: August 2003

Due to their complex functions and dynamics, ports have a complex structure. Complex structures are investigated through simulation techniques instead of analytical methods. Simulation of port systems can be carried out for different goals such as port design, planning, capacity increase, and productivity. In this study, bottleneck points were investigated under overloading conditions. Based on the results generated through simulation experiments, it was determined that the most critical bottleneck points are created by loading/unloading vehicles. An investment strategy was applied to the model at this point for load balancing of the port. As a result, simulation was used to study improvements by adding resources within economic limitations.
Monitoring Antitobacco Sentiment among Community Leaders
Authors: Bechtel Gordon G. , Lyons-Lepke Elaine M.
Published: August 2003

Two public health objectives, one methodological and the other substantive, are realized in the present study. First, average survey ratings are replaced by negated mean cumulative logits (MCLs), which have the advantage of interitem commensuration. Second, these negated MCLs improve the analysis of two Florida tobacco control surveys of community leaders. Because of their common logit metric, negated MCLs for different item types are compared on their expressed antitobacco sentiment. They are also averaged to construct a precise indicator of overall sentiment. These results show that in 1998 and 1999, community leaders were most averse to selling to minors, kids buying cigarettes, and restaurant and workplace smoking. The latter aversion anticipated voters' overwhelming support of the 2002 Florida constitutional amendment prohibiting smoking in restaurants and workplaces. The authors hope that this analysis for antitobacco programs will improve other substance-abuse monitoring with surveys whose items are yet unwritten.
Representations and Uses of the Intranet: A Comparative Case Study
Authors: Pellegrino Giuseppina
Published: August 2003

The article focuses on Intranet technology as the result of overlapping negotiations among social actors inside organizations. Such negotiations are aimed at establishing and embedding specific relations and representations of work, communication, and learning into the technological artifact. Two case studies are presented to analyze practices and processes of implementation and use of the Intranet. The fieldwork, carried out in two companies in Italy and the United Kingdom, shows how specific contexts and organizational histories can affect such processes. Despite the “optimistic” imagery associated with Intranet technology and the high expectations about its communicative and economic efficiency, the article points out many constraints in the process of implementation and use. Company history and culture, skills and work groups, and use of other technologies and media are relevant factors to account for the current use of the two systems and their low degree of integration into everyday working and communicative practices.