Measurement of the W-->taunu production cross section in pp collisions at square root s=1.8 TeV

We report on a measurement of sigma(pp-->W+X)B(W-->taunu) in pp collisions at sqrt[s]=1.8 TeV at the Fermilab Tevatron. The measurement is based on an integrated luminosity (lum) of 18 pb-1 of data collected with the D0 detector during 1994-1995. We find that sigma(pp-->W+X)B(W-->taunu)=2.22+/-0.09 (stat)+/-0. 10 (syst)+/-0.10 (lum) nb. Lepton universality predicts that the ratio of the tau and electron electroweak charged current couplings to the W boson, gWtau/gWe, be unity. We find gWtau/gWe=0.980+/-0.031, in agreement with lepton universality.

A 500-kb region on chromosome 16p13.1 contains the pseudoxanthoma elasticum locus: high-resolution mapping and genomic structure

We have recently mapped the genetic defect underlying pseudoxanthoma elasticum (PXE), an inherited disorder characterized by progressive calcification of elastic fibers in skin, eye, and cardiovascular system, to chromosome 16p 13.1. Here we report further data on the fine-mapping and genomic structure of this locus. Haplotype analysis of informative PXE families narrowed the locus to an interval of less than 500 kb located between markers D16B9621 and D16S764. Three overlapping YAC clones were found to cover this region through YAC-STS content mapping. An overlapping BAC contig was then constructed to cover this interval and the surrounding region. About 80% of this chromosomal region has been fully sequenced using the BAC shotgun technique. Gene content and sequence analysis predicted four genes (MRP1, MRP6, PM5, and a novel transcript) and two pseudogenes (ARA and PKDI) within this interval. By screening a somatic cell hybrid panel we were able to precision-map the breakpoint of Cy185 and the starting point of a chromosomal duplication within 20 kb of BAC A962B4. The present data further refine the localization of PXE, provide additional physical cloning resources, and will aid in the eventual identification of the genetic defect causing PXE.

The genetic contribution of single male immigrants to small, inbred populations: a laboratory study using Drosophila melanogaster

This study examined the genetic contribution of single male immigrants to small, inbred laboratory populations of Drosophila melanogaster. Genetic contribution was assessed by measuring the relative frequency of immigrant marker alleles in the first and second generations after immigration, while controlling for any selection effects at the marker locus, and for the experience of male immigrants. When immigrants were outbred, the mean frequency of the immigrant allele was significantly higher than its initial frequency, in both the first and second generations after immigration. There was no significant change in allele frequency for populations receiving inbred immigrants. The increase in allele frequency for outbred immigrants was attributed to an initial outbred vigour fitness advantage of immigrant males over resident males experiencing inbreeding depression. Hybrid vigour of immigrant progeny and the rare-male effect did not have a statistically significant role in the fitness advantage of the immigrant allele. The results suggest that inbreeding may have a considerable impact on the contribution of immigrants to the genetic diversity of populations.

Outcome of pediatric thromboembolic disease: a report from the Canadian Childhood Thrombophilia Registry

The outcome for children with deep vein thrombosis (DVT) and pulmonary embolism (PE) is unknown. An understanding of morbidity and mortality of DVT/PE is crucial to the development of rational treatment protocols. The Canadian Childhood Thrombophilia Registry has followed 405 children aged 1 mo to 18 y with DVT/PE for a mean of 2.86 y (range, 2 wk to 6 y) to assess outcome. The all-cause mortality was 65 of 405 children (16%). Mortality directly attributable to DVT/PE occurred in nine children (2.2%), all of whom had central venous line-associated thrombosis. Morbidity was substantial, with 33 children (8.1%) having recurrent thrombosis, and 50 children (12.4%) having postphlebitic syndrome. Recurrent thrombosis and postphlebitic syndrome were more common in older children, although deaths occurred equally in all age groups. The incidence of recurrent thrombosis and postphlebitic syndrome are likely underestimated because of difficulties in diagnosis, especially in younger children. The significant mortality and morbidity found in our study supports the need for international multicenter randomized clinical trials to determine optimal prophylactic and therapeutic treatment for children with DVT/PE.

Identification of a novel E2F3 product suggests a mechanism for determining specificity of repression by Rb proteins

The tumor suppressor function of Rb is intimately related to its ability to interact with E2F and repress the transcription of E2F target genes. Here we describe a novel E2F product that specifically interacts with Rb in quiescent cells. This novel E2F, which we term E2F3b, is encoded by a unique mRNA transcribed from an intronic promoter within the E2F3 locus. The E2F3b RNA differs from the previously characterized E2F3 RNA, which we now term E2F3a, by the utilization of a unique coding exon. In contrast to the E2F3a product that is tightly regulated by cell growth, the E2F3b product is expressed equivalently in quiescent and proliferating cells. But, unlike the E2F4 and E2F5 proteins, which are also expressed in quiescent cells and form complexes with the p130 protein, the E2F3b protein associates with Rb and represents the predominant E2F-Rb complex in quiescent cells. Thus, the previously described specificity of Rb function as a transcriptional repressor in quiescent cells coincides with the association of Rb with this novel E2F product.

Prevalence and correlates of smokeless tobacco use in a sample of Connecticut students

We examined the prevalence of smokeless tobacco use, and its relationship to other risky behaviors in Connecticut school children in grades four through 12 (n=31,861). Less than one per cent of students in grades 4-8, and four per cent of those in grades 9-12, used smokeless tobacco. Eighty-two percent of all users were white males. Among high school males, the prevalences of risk-taking behaviors and feelings of stress and depression were significantly higher among users than non-users. Among high school males, the highest prevalences of risky behaviors and stress indicators were reported by joint users of cigarettes and smokeless tobacco.

The genome sequence of Drosophila melanogaster

The fly Drosophila melanogaster is one of the most intensively studied organisms in biology and serves as a model system for the investigation of many developmental and cellular processes common to higher eukaryotes, including humans. We have determined the nucleotide sequence of nearly all of the approximately 120-megabase euchromatic portion of the Drosophila genome using a whole-genome shotgun sequencing strategy supported by extensive clone-based sequence and a high-quality bacterial artificial chromosome physical map. Efforts are under way to close the remaining gaps; however, the sequence is of sufficient accuracy and contiguity to be declared substantially complete and to support an initial analysis of genome structure and preliminary gene annotation and interpretation. The genome encodes approximately 13,600 genes, somewhat fewer than the smaller Caenorhabditis elegans genome, but with comparable functional diversity.

A whole-genome assembly of Drosophila

We report on the quality of a whole-genome assembly of Drosophila melanogaster and the nature of the computer algorithms that accomplished it. Three independent external data sources essentially agree with and support the assembly's sequence and ordering of contigs across the euchromatic portion of the genome. In addition, there are isolated contigs that we believe represent nonrepetitive pockets within the heterochromatin of the centromeres. Comparison with a previously sequenced 2.9- megabase region indicates that sequencing accuracy within nonrepetitive segments is greater than 99. 99% without manual curation. As such, this initial reconstruction of the Drosophila sequence should be of substantial value to the scientific community.

A dominant-negative peroxisome proliferator-activated receptor gamma (PPARgamma) mutant is a constitutive repressor and inhibits PPARgamma-mediated adipogenesis

The nuclear receptor peroxisome proliferator-activated receptor gamma (PPARgamma) promotes adipocyte differentiation, exerts atherogenic and anti-inflammatory effects in monocyte/macrophages, and is believed to mediate the insulin-sensitizing action of antidiabetic thiazolidinedione ligands. As no complete PPARgamma antagonists have been described hitherto, we have constructed a dominant-negative mutant receptor to inhibit wild-type PPARgamma action. Highly conserved hydrophobic and charged residues (Leu(468) and Glu(471)) in helix 12 of the ligand-binding domain were mutated to alanine. This compound PPARgamma mutant retains ligand and DNA binding, but exhibits markedly reduced transactivation due to impaired coactivator (cAMP-response element-binding protein-binding protein and steroid receptor coactivator-1) recruitment. Unexpectedly, the mutant receptor silences basal gene transcription, recruits corepressors (the silencing mediator of retinoid and thyroid receptors and the nuclear corepressor) more avidly than wild-type PPARgamma, and exhibits delayed ligand-dependent corepressor release. It is a powerful dominant-negative inhibitor of cotransfected wild-type receptor action. Furthermore, when expressed in primary human preadipocytes using a recombinant adenovirus, this PPARgamma mutant blocks thiazolidinedione-induced differentiation, providing direct evidence that PPARgamma mediates adipogenesis. Our observations suggest that, as in other mutant nuclear receptor contexts (acute promyelocytic leukemia, resistance to thyroid hormone), dominant-negative inhibition by PPARgamma is linked to aberrant corepressor interaction. Adenoviral expression of this mutant receptor is a valuable means to antagonize PPARgamma signaling.

Revision of the International Classification of Impairments, Disabilities, and Handicaps: developmental issues

Variability in approaches to define and classify disability has constituted persistent problems in documenting the epidemiology of disability and providing appropriate services. The major institutions of health care, mental health, and welfare often have separate systems of classification and terminology related to defining eligibility for programs and funding for services. In 1980, the International Classification of Impairments, Disabilities and Handicaps-ICIDH was published by the World Health Organization as a companion document of the International Classification of Disease to document the consequences of illness or injury. Current problems concerning the classification of childhood disability in health, education, and related services have resulted in growing interest in the revision of the ICIDH as a classification tool. The strengths and limitations of the ICIDH are examined in general, as well as with specific reference to its ability to document the nature and epidemiology of childhood disability. This paper (1) describes the ICIDH taxonomy and representative contributions; (2) reviews issues and concerns contributing to its revision; (3) summarizes changes in the revised ICIDH2 draft document, and (4) identifies issues of particular relevance to children and public health applications.

Human BAC ends quality assessment and sequence analyses

End sequences from bacterial artificial chromosomes (BACs) provide highly specific sequence markers in large-scale sequencing projects. To date, we have generated >300,000 end sequences from >186,000 human BAC clones with an average read length of >460 bp for a total of 141 Mb covering approximately 4.7% of the genome. Over 60% of the clones have BAC end sequences (BESs) from both ends representing more than fivefold coverage of the human genome by the paired-end clones. Our quality assessments and sequence analyses indicate that BESs from human BAC libraries developed at The California Institute of Technology (CalTech) and Roswell Park Cancer Institute have similar properties. The analyses have highlighted differences in insert size for different segments of the CalTech library. Problems with the fidelity of tracking of sequence data back to physical clones have been observed in some subsets of the overall BES dataset. The annotation results of BESs for the contents of available genomic sequences, sequence tagged sites, expressed sequence tags, protein encoding regions, and repeats indicate that this resource will be valuable in many areas of genome research.

NOX 100, a nitric oxide scavenger, enhances cardiac allograft survival and promotes long-term graft acceptance

BACKGROUND

We examined the role of nitrosative stress in allograft destruction.

METHODS

Rats undergoing cardiac transplants received NOX-100, a water-soluble nitric oxide (NO) scavenger with antioxidant properties, with or without low-dose cyclosporine (CsA). Graft survival, NO production, and nuclear factor kappa B (NF-kappaB) activity were studied.

RESULT

Using NOX-100 daily until rejection prolonged graft survival (11.6+/-0.6 vs. 7.4+/-0.2 days; P<0.05). Daily low-dose CsA (2.5 mg/kg im) for 7 days or until rejection also prolonged survival (12.6+/-0.5 and 21.6+/-1.6 days, respectively; P<0.01 vs. Controls). Low-dose CsA for 7 days and NOX-100 for 30 days prolonged graft survival (45.0+/-4.7 days; P<0.01 vs. all groups.). NOX-100 had no effect on whole blood CsA levels. Combination therapy until Day 100 resulted in 1 graft loss at Day 116 and indefinite survival in 3 animals (>300 days), which accepted a second WF strain heart without further immunosuppressive therapy but promptly rejected a third party (ACI) cardiac allograft. NOX-100 and CsA reduced nitrate and nitrite, and combination therapy completely normalized NO through to Day 30. Electron paramagnetic resonance spectroscopic analysis demonstrated reduction of signals for nitrosylmyoglobin and nitrosyl-heme with NOX-100 and elimination of signals with CsA alone or combination therapy. Activity of myocardial NF-kappaB decreased with monotherapy vs. untreated allografts. Combination therapy resulted in further inhibition of NF-kappaB up to Day 30. The extent of graft survival correlated with the extent of NO scavenging and NF-kappaB inhibition. Short-term combination therapy had no effect on graft lymphocytic infiltrate on Days 15, 20, and 30.

CONCLUSION

These data support a role for both oxidative and nitrosative stress in rejection and the immunoregulatory potential of antioxidant therapy after transplantation.

Reversible integer-to-integer wavelet transforms for image compression: performance evaluation and analysis

In the context of image coding, a number of reversible integer-to-integer wavelet transforms are compared on the basis of their lossy compression performance, lossless compression performance, and computational complexity. Of the transforms considered, several were found to perform particularly well, with the best choice for a given application depending on the relative importance of the preceding criteria. Reversible integer-to-integer versions of numerous transforms are also compared to their conventional (i.e., nonreversible real-to-real) counterparts for lossy compression. At low bit rates, reversible integer-to-integer and conventional versions of transforms were found to often yield results of comparable quality. Factors affecting the compression performance of reversible integer-to-integer wavelet transforms are also presented, supported by both experimental data and theoretical arguments.

Pediatric cervical spine injuries: report of 102 cases and review of the literature

OBJECT

To evaluate and review their experience with pediatric cervical injuries and factors affecting outcome, the authors conducted a retrospective clinical study of 102 cases (65% boys, 35% girls) of pediatric cervical spine injuries treated in the last decade. This study is an extension of and comparison with their earlier experience.

METHODS

Patients were divided into two age groups-birth to 9 years (Group I) and 10 to 16 years of age (Group 2)- and managed according to status at presentation and type of injury. Thirty patients were managed surgically and 72 non-surgically (42 wore a halo brace and 30 wore hard collars or custom-molded braces). Motor vehicle accidents were the most common cause of injury, and 40% were associated with head injury. Patients in the younger-age group (Group 1) sustained more neurological injuries than the older patients in Group 2, and most injuries were in the upper cervical spine. Of the 38 children in Group 1, in 39% a subluxation was present and in 29% a fracture or fracture/subluxation was demonstrated. Of the patients in Group 2, 80% had sustained fractures or fracture/subluxations. Vertebral fractures were the most common radiological findings (32%). At late follow-up review (mean 5 years), solid fusions were demonstrated in all patients. Neurological deterioration did not occur in any patient. The mortality rate was 16%. Compared with the authors' earlier report, the incidence of cases with pediatric cervical injuries increased, as did the number managed surgically. Various fusion techniques were used, and neurological and fusion outcomes improved as compared with the previous report.

CONCLUSIONS

The prognosis of neurological recovery from pediatric cervical spine injuries is related to the severity of the initial neurological injury. Management must be tailored to the patient's age, neurological status, and type and level of injury. Compared with our earlier experience, fusion and instrumentation procedures were used more frequently. Different types of fusion and instrumentation procedures can be performed safely in children and produce good outcomes.

Molecular structure and evolution of an alpha satellite/non-alpha satellite junction at 16p11

We have determined the detailed molecular structure and evolution of an alpha satellite junction from human chromosome 16p11. The analysis reveals that the alpha satellite sequence bordering the transition lacks higher-order structure and that the non-alpha satellite portion consists of a mosaic of duplicated segments of complex evolutionary origin. The 16p11 junction was formed recently (5-10 million years ago) by the duplication and transposition of genomic segments from Xq28 and 4q24. Once this mosaic structure was formed, a larger complex was spread among multiple pericentromeric regions. This resulted in the formation of large (>62 kb) paralogous segments that share a high degree ( approximately 97%) of sequence similarity. Both phylogenetic and comparative analyses indicate that these pericentromeric-directed duplications occurred around the time of the divergence of the human, gorilla and chimpanzee lineages, resulting in the subtle restructuring of the primate genome among these species. The available data suggest that such chimeric structures are a general property of several different human chromosomes near their alpha satellite junctions.

Phylogeography of the Australian dunnart Sminthopsis crassicaudata (Marsupialia : Dasyuridae)

Analyses of mitochondrial DNA (mtDNA) and allozymes are used to investigate the population genetic structure, phylogeography and systematics of the fat-tailed dunnart, Sminthopsis crassicaudata. Phylogenetic analyses of control region sequences reveal the presence of two major mtDNA haplotype clades. A survey of the distribution of the two clades using diagnostic restriction endonucleases shows that one clade is restricted to southeast Australia whereas the second clade occupies the remaining central to western range of S. crassicaudata. Allozyme electrophoresis also shows concordant patterns of population structure, with significant differences in allele frequency at three loci between populations in the southeast and northwest. Together, the mtDNA and allozyme data provide evidence that S. crassicaudata consists of two Evolutionarily Significant Units (ESUs). The distribution of each ESU is not concordant with the distribution of the subspecies of S. crassicaudata, and we propose that the current subspecies classification neither reflects the major genetic subdivisions present within S. crassicaudata nor would be appropriate for any future conservation management. The level of divergence between mtDNA clades (3.4%) is indicative of cladogenesis in the Pleistocene and reflects a long-term barrier to maternal gene flow between these two populations. One potential historical barrier was Lake Bungunnia, which persisted in the Murray basin over much of the Pleistocene.

Sequence and analysis of chromosome 2 of the plant Arabidopsis thaliana

Arabidopsis thaliana (Arabidopsis) is unique among plant model organisms in having a small genome (130-140 Mb), excellent physical and genetic maps, and little repetitive DNA. Here we report the sequence of chromosome 2 from the Columbia ecotype in two gap-free assemblies (contigs) of 3.6 and 16 megabases (Mb). The latter represents the longest published stretch of uninterrupted DNA sequence assembled from any organism to date. Chromosome 2 represents 15% of the genome and encodes 4,037 genes, 49% of which have no predicted function. Roughly 250 tandem gene duplications were found in addition to large-scale duplications of about 0.5 and 4.5 Mb between chromosomes 2 and 1 and between chromosomes 2 and 4, respectively. Sequencing of nearly 2 Mb within the genetically defined centromere revealed a low density of recognizable genes, and a high density and diverse range of vestigial and presumably inactive mobile elements. More unexpected is what appears to be a recent insertion of a continuous stretch of 75% of the mitochondrial genome into chromosome 2.

Genome duplications and other features in 12 Mb of DNA sequence from human chromosome 16p and 16q

Several publicly funded large-scale sequencing efforts have been initiated with the goal of completing the first reference human genome sequence by the year 2005. Here we present the results of analysis of 11.8 Mb of genomic sequence from chromosome 16. The apparent gene density varies throughout the region, but the number of genes predicted (84) suggests that this is a gene-poor region. This result may also suggest that the total number of human genes is likely to be at the lower end of published estimates. One of the most interesting aspects of this region of the genome is the presence of highly homologous, recently duplicated tracts of sequence distributed throughout the p-arm. Such duplications have implications for mapping and gene analysis as well as the predisposition to recurrent chromosomal structural rearrangements associated with genetic disease.

Sequence-tagged connectors: a sequence approach to mapping and scanning the human genome

The sequence-tagged connector (STC) strategy proposes to generate sequence tags densely scattered (every 3.3 kilobases) across the human genome by arraying 450,000 bacterial artificial chromosomes (BACs) with randomly cleaved inserts, sequencing both ends of each, and preparing a restriction enzyme fingerprint of each. The STC resource, containing end sequences, fingerprints, and arrayed BACs, creates a map where the interrelationships of the individual BAC clones are resolved through their STCs as overlapping BAC clones are sequenced. Once a seed or initiation BAC clone is sequenced, the minimum overlapping 5' and 3' BAC clones can be identified computationally and sequenced. By reiterating this "sequence-then-map by computer analysis against the STC database" strategy, a minimum tiling path of clones can be sequenced at a rate that is primarily limited by the sequencing throughput of individual genome centers. As of February 1999, we had deposited, together with The Institute for Genomic Research (TIGR), into GenBank 314,000 STCs ( approximately 135 megabases), or 4.5% of human genomic DNA. This genome survey reveals numerous genes, genome-wide repeats, simple sequence repeats (potential genetic markers), and CpG islands (potential gene initiation sites). It also illustrates the power of the STC strategy for creating minimum tiling paths of BAC clones for large-scale genomic sequencing. Because the STC resource permits the easy integration of genetic, physical, gene, and sequence maps for chromosomes, it will be a powerful tool for the initial analysis of the human genome and other complex genomes.

1H-NMRD and 17O-NMR assessment of water exchange and rotational dynamics of two potential MRI agents: MP-1177 (an extracellular agent) and MP-2269 (a blood pool agent)

The parameters that govern water proton magnetic relaxation (e.g. water exchange rates, and rotational and electronic correlation times) of representatives of two classes of Gd(III) complexes have been estimated, using two different approaches and the results compared with those derived for known analogs. The complexes studied are: (i) the non-ionic GdDTPA-bis(-methoxyethyl-amide) [Gd(DTPA-BMEA)], a typical small-molecule extracellular MR agent, and (ii) the ionic Gd(III) complex of 4-pentylbicyclo[2.2.2]octane-1-carboxyl-di-L-aspartyl-lysine-deriv ed-DTPA [GdL]4-, a prototype MR blood pool agent, which binds to serum albumin in vivo through non-covalent hydrophobic interactions. An 17O-NMR study of [Gd(DTPA-BMEA)] gives a water exchange rate constant of k(ex)298 = (0.39 +/- 0.02) x 10(6) s(-1), identical to that for the bismethylamide analog [Gd(DTPA-BMA)]. Both approaches yield longer rotational correlation times for [Gd(DTPA-BMEA)], consistent with its higher molecular weight. An 17O-NMR study of [GdL]4- gives a water exchange rate constant of k(ex)298 = (4.2 +/- 0.1) x 10(6) s(-1), identical to that for [Gd(DTPA)]2-. The water exchange rate on [GdL]4- did not decrease considerably when bound to albumin, the lowest limit is k(ex,GdL-BSA) = k(ex,GdL)/2. Both approaches yield identical rotational correlation times for [GdL]4-, however, it was difficult to derive a consistent rotational constant for the albumin-bound [GdL]4- using the different approaches (values ranged between 1.0 and 23.0 ns).