Ratio of jet cross sections at square root of s = 630 GeV and 1800 GeV

The D0 Collaboration has measured the inclusive jet cross section in barpp collisions at square root of s = 630 GeV. The results for pseudorapidities (eta)<0.5 are combined with our previous results at square root of s = 1800 GeV to form a ratio of cross sections with smaller uncertainties than either individual measurement. Next-to-leading-order QCD predictions show excellent agreement with the measurement at 630 GeV; agreement is also satisfactory for the ratio. Specifically, despite a 10% to 15% difference in the absolute magnitude, the dependence of the ratio on jet transverse momentum is very similar for data and theory.

Ratios of multijet Cross Sections in p p collisions at radical(s) = 1.8 TeV

We report on a study of the ratio of inclusive three-jet to inclusive two-jet production cross sections as a function of total transverse energy in p&pmacr; collisions at a center-of-mass energy sqrt[s] = 1.8 TeV, using data collected with the D0 detector during the 1992-1993 run of the Fermilab Tevatron Collider. The measurements are used to deduce preferred renormalization scales in perturbative O(alpha(3)(s)) QCD calculations in modeling soft-jet emission.

Mutation screening of the TNFRSF11A gene encoding receptor activator of NF kappa B (RANK) in familial and sporadic Paget's disease of bone and osteosarcoma

Paget's disease of bone (PDB) is a common disorder characterized by focal areas of increased and disorganized osteoclastic bone resorption, leading to bone pain, deformity, pathological fracture, and an increased risk of osteosarcoma. Genetic factors play an important role in the pathogenesis of Paget's disease. In some families, the disease has been found to be linked to a susceptibility locus on chromosome 18q21-22, which also contains the gene responsible for familial expansile osteolysis (FEO)--a rare bone dysplasia with many similarities to Paget's disease. Insertion mutations of the TNFRSF11A gene encoding Receptor Activator of NF kappa B (RANK) have recently been found to be responsible for FEO and rare cases of early onset familial Paget's disease. Loss of heterozygosity (LOH) affecting the PDB/FEO critical region has also been described in osteosarcomas suggesting that TNFRSF11A might also be involved in the development of osteosarcoma. In order to investigate the possible role of TNFRSF11A in the pathogenesis of Paget's disease and osteosarcoma, we conducted mutation screening of the TNFRSF11A gene in patients with familial and sporadic Paget's disease as well as DNA extracted from Pagetic bone lesions, an osteosarcoma arising in Pagetic bone and six osteosarcoma cell lines. No specific abnormalities of the TNFRSF11A gene were identified in a Pagetic osteosarcoma, the osteosarcoma cell lines, DNA extracted from Pagetic bone lesions, or DNA extracted from peripheral blood in patients with familial or sporadic Paget's disease including several individuals with early onset Paget's disease. These data indicate that TNFRSF11A mutations contribute neither to the vast majority of cases of sporadic or familial PDB, nor to the development of osteosarcoma.

Sun protection practices in preadolescents and adolescents: a school-based survey of almost 25,000 Connecticut schoolchildren

Sun protection practices in children and adolescents fall well below national recommendations. We present the results of a survey of sun protection use and other health-related behaviors in a sample of Connecticut Caucasian students aged 9 through 18 years (N = 24,645). Our objectives were to estimate the prevalence of sun protection use and to evaluate the relationship between sun protection use and health-risk behaviors and attitudes about appearance. We present data from 1988 through 1995 from the Connecticut Health Check, a health risk appraisal survey sponsored by the Connecticut Department of Public Health. Students enrolled in public and private elementary junior as well as senior high schools took the self-administered anonymous survey, which included multiple-choice questions about use of sun protection, cigarettes, and alcohol and about body image and self-esteem. We report prevalence proportions for use of sun protection by demographic features. We compared the proportion of students in 3 categories of outcome (always, sometimes, and never use sun protection) who reported various health-risk behaviors. Twenty percent of the sample reported always using sun protection; this is well below national goals set forth in the Healthy People 2000 recommendations. Sun protection use was inversely related to age and was higher among girls than boys at all ages. At all ages, students who did not use sun protection were more likely than those who did to report other health risk behaviors, such as use of cigarettes and alcohol. The data suggested that use of sun protection is associated with positive attitudes about appearance and self-image. Use of sun protection may be one component of an overall mode of health awareness and behavior. Programs promoting safe sun practices should target boys and be integrated into an overall campaign aimed at other risk-taking behaviors.

Geographic variation in antisnake tactics: the evolution of scent-mediated behavior in a lizard

We used modern comparative methods to examine the evolution of scent-mediated antisnake behavior in the rock-dwelling velvet gecko (Oedura lesueurii). The selective agent is a snake species (broad-headed snake, Hoplocephalius bungaroides) that feeds primarily on velvet geckos by remaining sedentary in rock crevices for days or weeks, waiting to ambush lizards. The past and present distribution of this predator is well documented because of its threatened conservation status. We used this information to sample lizards from three populations distributed with snakes (sympatric) and three populations that appear never to have been distributed with snakes (allopatric) in each of two widespread but geographically distinct genetic groups of velvet gecko (as determined using allozyme electrophoresis). Wild-caught immature geckos from sympatric populations showed higher tongue-flick rates and stronger shifts in locomotion (increased duration of crawling and remaining stationary while pressed against the rock) toward snake-scented rocks than did lizards from allopatric populations. However, predation environment did not significantly affect a lizard's tendency to display other typical antisnake tactics such as tail waving or fleeing. These results were highly repeatable across the two sampled genetic groups of velvet gecko, despite demonstrable genetic divergence between groups. Experiments with hatchling lizards that had no experience with predators indicate that qualitative components of antisnake behaviors are probably inherited. The method of phylogenetically independent contrasts strongly suggests that the presence or absence of snakes has driven the evolution of behavior in velvet geckos. Collectively, these results provide support for an often suggested but speculative expectation that prey can adapt to predation pressure on a local scale.

Inclusive jet production in pp(macro) collisions

We report a new measurement of the pseudorapidity (eta) and transverse-energy ( E(T)) dependence of the inclusive jet production cross section in pp(macro) collisions at square root of s = 1.8 TeV using 95 pb(-1) of data collected with the D0 detector at the Fermilab Tevatron. The differential cross section d(2)sigma/(dE(T)d eta) is presented up to eta = 3, significantly extending previous measurements. The results are in good overall agreement with next-to-leading order predictions from QCD and indicate a preference for certain parton distribution functions.

The sequence of the human genome

A 2.91-billion base pair (bp) consensus sequence of the euchromatic portion of the human genome was generated by the whole-genome shotgun sequencing method. The 14.8-billion bp DNA sequence was generated over 9 months from 27,271,853 high-quality sequence reads (5.11-fold coverage of the genome) from both ends of plasmid clones made from the DNA of five individuals. Two assembly strategies-a whole-genome assembly and a regional chromosome assembly-were used, each combining sequence data from Celera and the publicly funded genome effort. The public data were shredded into 550-bp segments to create a 2.9-fold coverage of those genome regions that had been sequenced, without including biases inherent in the cloning and assembly procedure used by the publicly funded group. This brought the effective coverage in the assemblies to eightfold, reducing the number and size of gaps in the final assembly over what would be obtained with 5.11-fold coverage. The two assembly strategies yielded very similar results that largely agree with independent mapping data. The assemblies effectively cover the euchromatic regions of the human chromosomes. More than 90% of the genome is in scaffold assemblies of 100,000 bp or more, and 25% of the genome is in scaffolds of 10 million bp or larger. Analysis of the genome sequence revealed 26,588 protein-encoding transcripts for which there was strong corroborating evidence and an additional approximately 12,000 computationally derived genes with mouse matches or other weak supporting evidence. Although gene-dense clusters are obvious, almost half the genes are dispersed in low G+C sequence separated by large tracts of apparently noncoding sequence. Only 1.1% of the genome is spanned by exons, whereas 24% is in introns, with 75% of the genome being intergenic DNA. Duplications of segmental blocks, ranging in size up to chromosomal lengths, are abundant throughout the genome and reveal a complex evolutionary history. Comparative genomic analysis indicates vertebrate expansions of genes associated with neuronal function, with tissue-specific developmental regulation, and with the hemostasis and immune systems. DNA sequence comparisons between the consensus sequence and publicly funded genome data provided locations of 2.1 million single-nucleotide polymorphisms (SNPs). A random pair of human haploid genomes differed at a rate of 1 bp per 1250 on average, but there was marked heterogeneity in the level of polymorphism across the genome. Less than 1% of all SNPs resulted in variation in proteins, but the task of determining which SNPs have functional consequences remains an open challenge.

Acquired activated protein C resistance is associated with lupus anticoagulants and thrombotic events in pediatric patients with systemic lupus erythematosus

Acquired activated protein C resistance (APCR) has been hypothesized as a possible mechanism by which antiphospholipid antibodies (APLAs) cause thrombotic events (TEs). However, available evidence for an association of acquired APCR with APLAs is limited. More importantly, an association of acquired APCR with TEs has not been demonstrated. The objective of the study was to determine, in pediatric patients with systemic lupus erythematosus (SLE), whether (1) acquired APCR is associated with the presence of APLAs, (2) APCR is associated with TEs, and (3) there is an interaction between APCR and APLAs in association with TEs. A cross-sectional cohort study of 59 consecutive, nonselected children with SLE was conducted. Primary clinical outcomes were symptomatic TEs, confirmed by objective radiographic tests. Laboratory testing included lupus anticoagulants (LAs), anticardiolipin antibodies (ACLAs), APC ratio, protein S, protein C, and factor V Leiden. The results revealed that TEs occurred in 10 (17%) of 59 patients. Acquired APCR was present in 18 (31%) of 58 patients. Acquired APCR was significantly associated with the presence of LAs but not ACLAs. Acquired APCR was also significantly associated with TEs. There was significant interaction between APCR and LAs in the association with TEs. Presence of both APCR and LAs was associated with the highest risk of a TE. Protein S and protein C concentrations were not associated with the presence of APLAs, APCR, or TEs. Presence of acquired APCR is a marker identifying LA-positive patients at high risk of TEs. Acquired APCR may reflect interference of LAs with the protein C pathway that may represent a mechanism of LA-associated TEs. (Blood. 2001;97:844-849)

Search for large extra dimensions in dielectron and diphoton production

We report a search for effects of large extra spatial dimensions in pp collisions at a center-of-mass energy of 1.8 TeV with the D0 detector, using events containing a pair of electrons or photons. The data are in good agreement with the expected background and do not exhibit evidence for large extra dimensions. We set the most restrictive lower limits to date, at the 95% C.L. on the effective Planck scale between 1.0 and 1.4 TeV for several formalisms and numbers of extra dimensions.

MRI contrast enhancement of necrosis by MP-2269 and gadophrin-2 in a rat model of liver infarction

RATIONALE AND OBJECTIVES

The mechanisms of action leading to specific localization of necrosis-avid contrast agents (NACAs) such as gadophrin-2 are not well defined. It has been suggested recently that agents with a high degree of serum albumin binding may also serve as NACAs by virtue of nonspecific hydrophobic interactions. The present MRI-histomorphology correlation study was conducted to verify the likelihood of the proposed albumin-binding mechanism by comparing an albumin-binding blood pool agent, MP-2269, with gadophrin-2 in a rat model of reperfused liver infarction.

METHODS

Reperfused infarction in the right liver lobe was surgically induced in six rats. Serial T1-weighted MRI was performed before and after intravenous injection of MP-2269 at 0.05 mmol/kg and repeated in the same rats 24 hours later after intravenous injection of gadophrin-2 at the same dosage (0.05 mmol/kg). The MR images were matched with corresponding histomorphological findings. The signal intensity and contrast ratio of infarcted and normal hepatic lobes were quantified and compared between the two agents during the postcontrast course.

RESULTS

Before contrast, the infarcted lobe was indiscernible from normal liver on T1-weighted MRI. Shortly after injection of both MP-2269 and gadophrin-2, a negative contrast occurred between infarcted and normal liver because of a strong liver signal intensity enhancement and an inferior uptake in the necrotic liver. On delayed phase (>60 minutes), a necrosis-specific contrast enhancement (contrast ratio 1.6) developed with gadophrin-2 but not with MP-2269. The MR images matched well with corresponding histomorphological findings.

CONCLUSIONS

Although both MP-2269 and gadophrin-2 feature an albumin-binding capacity, only gadophrin-2 displayed a persistent necrosis-specific contrast enhancement in the rat model of reperfused liver infarction. Therefore, the role of albumin binding in the mechanisms of NACAs should be reevaluated.

A SNP resource for human chromosome 22: extracting dense clusters of SNPs from the genomic sequence

The recent publication of the complete sequence of human chromosome 22 provides a platform from which to investigate genomic sequence variation. We report the identification and characterization of 12,267 potential variants (SNPs and other small insertions/deletions) of human chromosome 22, discovered in the overlaps of 460 clones used for the chromosome sequencing. We found, on average, 1 potential variant every 1.07 kb and approximately 18% of the potential variants involve insertions/deletions. The SNPs have been positioned both relative to each other, and to genes, predicted genes, repeat sequences, other genetic markers, and the 2730 SNPs previously identified on the chromosome. A subset of the SNPs were verified experimentally using either PCR-RFLP or genomic Invader assays. These experiments confirmed 92% of the potential variants in a panel of 92 individuals. [Details of the SNPs and RFLP assays can be found at http://www.sanger.ac.uk and in dbSNP.]

Analysis of antigen presenting cell derived exosomes, based on immuno-magnetic isolation and flow cytometry

We present a simple yet powerful method for the isolation and analysis of exosomes released by antigen-presenting cells (APC). Exosomes are small vesicles (40-90 nm) released by APC, and may have an immuno-regulatory function in vivo. Such exosomes originate from MHC class II peptide loading compartments and, as such, express high levels of MHC Class II. We have utilised magnetic beads, coated with monoclonal antibodies specific for HLA DP, DQ, DR for the specific isolation of exosomes from cell-free supernatants. Beads coated with exosomes are subsequently stained with conjugated antibodies, and analysed by flow cytometry. Characterisation of exosomes by this method demonstrated that exosomes derived from B-lymphocytes express abundant MHC Class I and II molecules. Other immunologically important molecules detected included the co-stimulatory molecules B7.1 (CD80) and B7.2 (CD86). The adhesion molecule ICAM-1 (CD54) was also detected. These exosomes also expressed the B cell marker CD20, and the complement inhibitory protein CD59. The expression of CD63, a lysosomal marker, was variable, and there was no detectable expression of transferrin receptor (CD71). Monocyte derived dendritic cells (cultured for 7 days in GM-CSF/IL-4), demonstrated an immature phenotype, and secreted exosomes with a similar phenotype, with abundant MHC molecules. The expression of CD63 was consistently strong, and the MHC Class I-like molecule CD1a was also present, suggesting a possible function in the presentation of lipid antigens. Again CD59 was expressed suggesting a possible role for APC exosomes in complement regulation. There was no detectable CD71, CD40, CD14, CD20 or CD83. Modification of the extraction protocol allowed a comparative analysis of exosome secretion under various conditions. Treatment of cells with calcium ionophore, or phorbol ester resulted in apparent increases in exosome release, while the phosphatidyl inositol 3-kinase inhibitor, wortmannin, reduced exosome secretion. The immuno-magnetic isolation and analysis of exosomes is a versatile and rapid tool for the analysis of APC exosomes, and may prove a valuable tool for the study of exosome biology.

Substantial allozyme diversity in the freshwater crayfish Parastacoides tasmanicus supports extensive cryptic speciation

Allozyme electrophoretic studies on the freshwater crayfish genus Parastacoides Clark suggest the presence of several cryptic species within this morphologically conservative taxon. Two independent allozyme studies were undertaken to assess the validity of the current taxonomy of this monotypic genus. An initial study examined 42 individuals from 10 sample sets for allozyme variation at 22 putative loci, and a subsequent study surveyed an additional 72 specimens from 20 sample sets at 16 putative loci. Both studies revealed the same general outcomes, namely: (1) several instances of sympatric species diagnosable at multiple allozyme loci; (2) numerous examples of putative allopatric species with significant levels of genetic divergence (25–81% fixed difference, 0.30–1.67 Nei distance) well beyond those found between conspecific populations of any parastacid; (3) broad genetic affinities among putative species are inconsistent with currently recognised morphotypes; and (4) low levels of within-population genetic variability, typical of parastacids. Although it is not possible to determine how many species are represented on the basis of these two preliminary studies, the allozyme data nevertheless indicate that an absolute minimum of 11 species and perhaps as many as 19 species are likely to be present in the genus. They indicate the need for a thorough taxonomic revision of the genus using both molecular and morphological data.

Consensus statement on the live organ donor

OBJECTIVE

To recommend practice guidelines for transplant physicians, primary care providers, health care planners, and all those who are concerned about the well-being of the live organ donor.

PARTICIPANTS

An executive group representing the National Kidney Foundation, and the American Societies of Transplantation, Transplant Surgeons, and Nephrology formed a steering committee of 12 members to evaluate current practices of living donor transplantation of the kidney, pancreas, liver, intestine, and lung. The steering committee subsequently assembled more than 100 representatives of the transplant community (physicians, nurses, ethicists, psychologists, lawyers, scientists, social workers, transplant recipients, and living donors) at a national conference held June 1-2, 2000, in Kansas City, Mo.

CONSENSUS PROCESS

Attendees participated in 7 assigned work groups. Three were organ specific (lung, liver, and kidney) and 4 were focused on social and ethical concerns (informed consent, donor source, psychosocial issues, and live organ donor registry). Work groups' deliberations were structured by a series of questions developed by the steering committee. Each work group presented its deliberations to an open plenary session of all attendees. This information was stored and shaped into a statement circulated electronically to all attendees for their comments, and finally approved by the steering committee for publication. The term consensus is not meant to convey universal agreement of the participants. The statement identifies issues of controversy; however, the wording of the entire statement is a consensus by approval of all attendees.

CONCLUSION

The person who gives consent to be a live organ donor should be competent, willing to donate, free from coercion, medically and psychosocially suitable, fully informed of the risks and benefits as a donor, and fully informed of the risks, benefits, and alternative treatment available to the recipient. The benefits to both donor and recipient must outweigh the risks associated with the donation and transplantation of the living donor organ.

Ethical issues surrounding adult-to-adult living donor liver transplantation

1. The ethical principle of utility is enhanced by living donor liver transplantation (LDLT). LDLT carries the potential to optimize efficient use of organs, minimize pretransplant morbidity and mortality, and increase availability of cadaveric organs. 2. The most serious ethical concerns in LDLT focus on the risks to the donor and relate to the principle of nonmaleficence-"do no harm". Although exact risk remains uncertain, there is potential for significant donor morbidity and even mortality. 3. Careful consideration must be given to development of the best approach to obtaining truly informed consent. 4. Specific criteria for LDLT should be developed for transplant centers, donors, and recipients. Informed consent should be standardized. 5. A national registry for donors and recipients of LDLT is needed.

Human enamel as a substrate for in vitro acid dissolution studies: influence of tooth surface and morphology

The variation in susceptibility of enamel to acid dissolution has been quantitatively assessed in vitro by examination of different surfaces of both maxillary and mandibular teeth of different morphology obtained from a pool of sound human teeth. The lingual/palatal surfaces of all teeth showed greater susceptibility to acid dissolution than the corresponding labial/buccal surfaces. The palatal surface of the maxillary teeth appeared more susceptible to acid than the lingual surface of the corresponding teeth in the mandible. The palatal surfaces of the maxillary teeth showed least variation in acid susceptibility, whilst the lingual surfaces of mandibular teeth and buccal/labial surfaces of teeth from both jaws showed much more variation between teeth of different morphology. These differences in susceptibility to acid dissolution probably reflect both developmental differences and post-eruptive changes in enamel and may contribute to the clinical presentation of dental disease. Importantly, the data indicates that careful selection of teeth for in vitro study of enamel dissolution processes is essential to minimise inter-sample variation. For such purposes, the palatal surface of the maxillary teeth appears to be most suitable.

Unraveling the realities of vascular access: the Network 11 experience

Arteriovenous (AV) fistulae are well recognized as the preferred vascular access for hemodialysis, yet national data show that only 23% of patients used an AV fistula in 1997. To identify barriers to the placement of native AV fistulae, the Renal Network of the Upper Midwest, Inc. (End-Stage Renal Disease [ESRD] Network 11) initiated a vascular access project to look at the process of referral for patients beginning hemodialysis in the first 6 months of 1999. Of these patients, 63% began hemodialysis with a catheter as the only access, 22% had an AV fistula placed (but only 14% used an AV fistula for their first dialysis treatment), and 15% began with a graft. About 40% of patients were referred to a nephrologist less than 1 month before dialysis, allowing little chance for permanent access placement. Yet 27% of patients used a catheter on the first hemodialysis treatment and were seen by a nephrologist more than 1 month before starting dialysis, indicating the presence of an opportunity to improve. At 6 months after initiation of dialysis, 25% of patients who began dialysis using a catheter were using an AV fistula and 35% were using a graft. Network 11 plans to use this information to promote early referral of patients to a nephrologist and subsequent prompt referral of such patients to a vascular surgeon. Other activities to improve vascular access management are also indicated.