Statistical analysis in epidemiologic studies is often hindered by missing data, and multiple imputation is increasingly being used to handle this problem. In a simulation study, the authors compared 2 methods for imputation that are widely available in standard software: fully conditional specification (FCS) or "chained equations" and multivariate normal imputation (MVNI). The authors created data sets of 1,000 observations to simulate a cohort study, and missing data were induced under 3 missing-data mechanisms. Imputations were performed using FCS (Royston's "ice") and MVNI (Schafer's NORM) in Stata (Stata Corporation, College Station, Texas), with transformations or prediction matching being used to manage nonnormality in the continuous variables. Inferences for a set of regression parameters were compared between these approaches and a complete-case analysis. As expected, both FCS and MVNI were generally less biased than complete-case analysis, and both produced similar results despite the presence of binary and ordinal variables that clearly did not follow a normal distribution. Ignoring skewness in a continuous covariate led to large biases and poor coverage for the corresponding regression parameter under both approaches, although inferences for other parameters were largely unaffected. These results provide reassurance that similar results can be expected from FCS and MVNI in a standard regression analysis involving variously scaled variables.

In November 2001, the 1st International Symposium on Concussion in Sport was held in Vienna, Austria to provide recommendations for the improvement of safety and health of athletes who suffer concussive injuries in ice hockey, football (soccer), and other sports. The 2nd International Symposium on Concussion in Sport was organised by the same group and held in Prague, Czech Republic in November 2004. It resulted in a revision and update of the Vienna consensus recommendations, which are presented here.

Proteolysis mediated by the interleukin 1 beta-converting enzyme (ICE) homologues is an important mechanism of the apoptotic process. The ICE homologue apopain/CPP-32/Yama (subsequently referred to as apopain) cleaves poly(ADP-ribose)polymerase (PARP) early during apoptosis. Additional apoptosis-specific protein cleavages have been observed in which the direct involvement of ICE-like proteases has been postulated. These substrates include the 70-kD protein component of the U1-ribonucleoprotein (U1-70kD), and the catalytic subunit of the DNA-dependent protein kinase (DNA-PKcs). The present studies demonstrate that U1-70kD and DNA-PKcs are excellent substrates for apopain, with cleavage occurring at sites that are highly similar to the cleavage site within PARP. The fragments generated from isolated protein substrates by apopain are identical to those observed in intact apoptotic cells, in apoptotic cell extracts, and in normal cell extracts to which apopain has been added. Like PARP, cleavage of these substrates in apoptotic cell extracts is abolished by nanomolar concentrations of Ac-DEVD-CHO and micromolar amounts of Ac-YVAD-CHO, confirming the involvement of apopain or an apopain-like activity. We propose that a central function of apopain or similar homologues in apoptosis is the cleavage of nuclear repair proteins, thereby abolishing their critical homeostatic functions.

Shigella, the etiological agent of dysentery, kills macrophages by inducing apoptosis. Deletion mutants in the invasion invasion plasmid antigen B (ipaB) of Shigella flexneri are not cytotoxic. Here, we localized IpaB to the cytoplasm of macrophages infected with S. flexneri. Purified IpaB induced apoptosis when microinjected into macrophages, indicating that IpaB is sufficient to induce apoptosis. Using a GST-IpaB fusion protein as a ligand in affinity purification, we isolated four IpaB binding proteins from macrophages which were identified as the precursor and the mature polypeptides of interleukin-1beta converting enzyme (ICE) or a highly homologous protease. We found that IpaB binds directly to ICE and this enzyme is activated during S. flexneri infection. Furthermore, specific inhibitors of ICE prevented Shigella-induced apoptosis.

The conformational properties of proteins can be probed with hydrogen/deuterium exchange mass spectrometry (HXMS). In order to maintain the deuterium label during LC/MS analyses, chromatographic separation must be done rapidly (usually in under 8-10 min) and at 0 degrees C. Traditional RP-HPLC with approximately 3-mum particles has shown generally poor chromatographic performance under these conditions and thereby has been prohibitive for HXMS analyses of larger proteins and many protein complexes. Ultraperformance liquid chromatography (UPLC) employs particles smaller than 2 mum in diameter to achieve superior resolution, speed, and sensitivity as compared to HPLC. UPLC has previously been shown to be compatible with the fast separation and low temperature requirements of HXMS. Here we present construction and validation of a custom UPLC system for HXMS. The system is based on the Waters nanoACQUITY platform and contains a Peltier-cooled module that houses the injection and switching valves, online pepsin digestion column, and C-18 analytical separation column. Single proteins in excess of 95 kDa and a four-protein mixture in excess of 250 kDa have been used to validate the performance of this new system. Near-baseline resolution was achieved in 6-min separations at 0 degrees C and displayed a median chromatographic peak width of approximately 2.7 s at half-height. Deuterium recovery was similar to that obtained using a conventional HPLC and ice bath. This new system represents a significant advancement in HXMS technology that is expected to make the technique more accessible and mainstream in the near future.

Due to worldwide distribution, high abundance and availability of physiologically diverse isolates the Roseobacter clade is one of the most intensively studied groups of marine bacteria. Organisms of this clade have been detected in a large variety of habitats, from coastal regions to deep-sea sediments and from polar ice to tropical latitudes, and constitute up to 25% of the total bacterial community. Use of a multitude of organic compounds, sulfur oxidation, aerobic anoxygenic photosynthesis, oxidation of carbon monoxide, DMSP demethylation, and production of secondary metabolites are some of the important traits found in this clade. Physiological characteristics and the different isolation sources indicate that organisms of the Roseobacter clade occupy various ecological niches. Since the first description of Roseobacter spp. in 1991, 38 affiliated and validated genera have been described. More than half of these descriptions have been published within the last 3 years. Genome sequencing of currently 40 different strains demonstrates enormous interest in the genetic and metabolic diversity of these bacteria. Plasmids with an enormous size range are also widespread in the Roseobacter clade indicating an adaptive genomic structure. Comparisons with other highly relevant groups, like the SAR11 clade, have shown drastic differences in genome organization.

Athletes, particularly those who are involved in sporting activities requiring repetitive overhead use of the arm (for example, tennis players, swimmers, baseball pitchers, and quarterbacks), may develop a painful shoulder. This is often due to impingement in the vulnerable avascular region of the supraspinatus and biceps tendons. With the passage of time, degeneration and tears of the rotator cuff may result. Pathologically the syndrome has been classified into Stage I (edema and hemorrhage), Stage II (fibrosis and tendonitis), and Stage III (tendon degeneration, bony changes, and tendon ruptures). The impingement syndrome may be a problem for the young, active, and competitive athlete as well as the casual weekend athlete. The "impingement sign" which reproduces pain and resulting facial expression when the arm is forceably forward flexed (jamming the greater tuberosity against the anteroinferior surface of the acromion) is the most reliable physical sign in establishing the diagnosis. Flexibility exercises, strengthening programs, and special training techniques are a preventive and treatment requirement. Rest and local modalities such as ice, ultrasound, and antiinflammatory agents are usually effective to lessen the inflammatory reaction. Surgical decompression by resecting the coracoacromial ligament or a more definitive anterior acromioplasty may rarely be indicated.

OBJECTIVE

The purpose of the study was to investigate the incidence, predictors, morbidity, and mortality associated with postoperative atrial fibrillation (AF) and its impact on intensive care unit (ICU) and postoperative hospital stay in patients undergoing cardiac surgery in the Department of Veterans Affairs (VA).

BACKGROUND

Postoperative AF after open cardiac surgery is rather common. The etiology of this arrhythmia and factors responsible for its genesis are unclear, and its impact on postoperative surgical outcomes remains controversial. The purpose of this special substudy was to elucidate the incidence of postoperative AF and the factors associated with its development, as well as the impact of AF on surgical outcome.

METHODS

The study population consisted of 3855 patients who underwent open cardiac surgery between September 1993 and December 1996 at 14 VA Medical Centers. Three hundred twenty-nine additional patients were excluded because of lack of complete data or presence of AF before surgery, and 3794 (98.4%) were male with a mean age of 63.7+/-9.6 years. Operations included coronary artery bypass grafting (CABG) (3126, 81%), CABG + AVR (aortic valve replacement) (228, 5.9%), CABG + MVR (mitral valve replacement) (35, 0.9%), AVR (231, 6%), MVR (41, 1.06%), CABG + others (95, 2.46%), and others (99, 2.5%). The incidence of postoperative AF was 29.6%. Multivariate logistic regression analysis of factors found significant on univariate analysis showed the following predictors of postoperative AF: preoperative patient risk predictors: advancing age (odds ratio [OR] 1.61, 95% confidence interval [CI] 1.48-1.75, p < 0.001), chronic obstructive pulmonary disease (OR 1.37, 95% CI 1.12-1.66, p < 0.001), use of digoxin within 2 weeks before surgery (OR 1.37, 95% CI 1.10-1.70, p < 0.003), low resting pulse rate <80 (OR 1.26, 95% CI 1.06-1.51, p < 0.009), high resting systolic blood pressure >120 (OR 1.19, 95% CI 1.02-1.40, p < 0.026), intraoperative process of care predictors: cardiac venting via right superior pulmonary vein (OR 1.42, 95% CI 1.21-1.67, p < 0.0001), mitral valve repair (OR 2.86, 95% CI 1.72-4.73, p < 0.0001) and replacement (OR 2.33, 95% CI 1.55-3.55, p < 0.0001), no use of topical ice slush (OR 1.29, 95% CI 1.10-1.49, p < 0.0009), and use of inotropic agents for greater than 30 minutes after termination of cardiopulmonary bypass (OR 1.36, 95% CI 1.16-1.59, p < 0.0001). Postoperative median ICU stay (3.6 days AF vs. 2 days no AF, p < 0.001) and hospital stay (10 days AF vs. 7 days no AF, p < 0.001) were higher in AF. Morbid events, hospital mortality, and 6-month mortality were significantly higher in AF (p < 0.001): ICU readmission 13% AF vs. 3.9% no AF, perioperative myocardial infarction 7.41 % AF vs. 3.36% no AF, persistent congestive heart failure 4.57% AF vs. 1.4% no AF, reintubation 10.59% AF vs. 2.47% no AF, stroke 5.26% AF vs. 2.44% no AF, hospital mortality 5.95% AF vs. 2.95% no AF, 6-month mortality 9.36% AF vs. 4.17% no AF.

CONCLUSIONS

Atrial fibrillation after cardiac surgery occurs in approximately one third of patients and is associated with an increase in adverse events in all measurable outcomes of care and increases the use of hospital resources and, therefore, the cost of care. Strategies to reduce the incidence of AF after cardiac surgery should favorably affect surgical outcomes and reduce utilization of resources and thus lower cost of care.

Oxygen is an essential element for normal life. However, reactive oxygen species (ROS) can also participate in deleterious reactions that can affect lipid, protein, and nucleic acid. Normal physiological function thus depends on a balance between these ROS and the scavenging systems that aerobic organisms have developed over millennia. Tilting of that balance towards a pro-oxidant state might result from both endogenous and exogenous causes. In the present paper, we elaborate on the thesis that the neurodegenerative effects of two drugs, namely methamphetamine (METH, ICE) and methylenedioxymethamphetamine (MDMA, Ecstasy) are due to ROS overproduction in monoaminergic systems in the brain. We also discuss the role of oxygen-based species in 6-hydroxydopamine (6-OHDA)-induced nigrostriatal dopaminergic degeneration and in Parkinson's disease. Studies are underway to identify specific cellular and molecular mechanisms that are regulated by oxygen species. These studies promise to further clarify the role of oxidative stress in neurodegeneration and in plastic changes that occur during the administration of addictive agents that affect the brain.

The timing and nature of the arrival and the subsequent expansion of modern humans into eastern Asia remains controversial. Using Y-chromosome biallelic markers, we investigated the ancient human-migration patterns in eastern Asia. Our data indicate that southern populations in eastern Asia are much more polymorphic than northern populations, which have only a subset of the southern haplotypes. This pattern indicates that the first settlement of modern humans in eastern Asia occurred in mainland Southeast Asia during the last Ice Age, coinciding with the absence of human fossils in eastern Asia, 50,000-100,000 years ago. After the initial peopling, a great northward migration extended into northern China and Siberia.

OBJECTIVE

Many patients with irritable bowel syndrome (IBS) show intestinal hypersensitivity to distension and sensitisation after repeated intestinal distensions. Abnormalities in endogenous pain inhibitory mechanisms, such as diffuse noxious inhibitory controls (DNIC), may be implicated and were investigated during brain functional magnetic resonance imaging (fMRI).

METHODS

fMRI was performed in 10 female patients with IBS (five constipated (IBS-C) and five with diarrhoea (IBS-D)) and 10 female healthy controls during rectal balloon distension alone or during activation of DNIC by painful heterotopic stimulation of the foot with ice water. Rectal pain was scored with and without heterotopic stimulation (0 = none, 10 = maximal).

RESULTS

Heterotopic stimulation decreased median rectal pain scores significantly in healthy controls (-1.5 (interquartile range -2 to -1); p = 0.001) but not in IBS-C (-0.7 (-1 to 0.5)), IBS-D (-0.5 (-1.5 to 0.5)), or in all IBS patients (0 (-1.5 to 1.3)). Brain activation changes during heterotopic stimulation differed highly significantly between IBS-C, IBS-D, and controls. The main centres affected were the amygdala, anterior cingulate cortex, hippocampus, insula, periaqueductal gray, and prefrontal cortex, which form part of the matrix controlling emotional, autonomic, and descending modulatory responses to pain.

CONCLUSIONS

IBS-C and IBS-D appear to have differing abnormal endogenous pain inhibitory mechanisms, involving DNIC and other supraspinal modulatory pathways.

The purpose of this study was to determine the effects of the cold pressor test on sympathetic outflow with direct measurements of nerve traffic in conscious humans and to test the strength of correlation between sympathetic nerve discharge and the changes in arterial pressure, heart rate, and plasma norepinephrine. In 25 healthy subjects, arterial pressure, heart rate, and muscle sympathetic nerve activity were measured with microelectrodes inserted percutaneously into a peroneal muscle nerve fascicle in the leg during immersion of the hand in ice water for 2 minutes. Arterial pressure rose steadily during the first and second minutes of the cold pressor test. Muscle sympathetic activity (burst frequency X amplitude) did not increase in the first 30 seconds of the test but increased from 230 +/- 27 to 386 +/- 52 units (mean +/- SE, p less than 0.05) by the end of the first minute of the test and to 574 +/- 73 (p less than 0.01) during the second minute. In contrast, heart rate increased maximally during the first 30 seconds of the cold pressor test and returned to control during the second minute. The increases in heart rate were abolished by beta-adrenergic blockade. The increases in muscle sympathetic activity during the cold pressor test were correlated with the increases in both mean arterial pressure (r = 0.86, p less than 0.01) and peripheral venous norepinephrine (r = 0.72, p less than 0.05); however, large changes in nerve traffic were associated with small changes in plasma norepinephrine.(ABSTRACT TRUNCATED AT 250 WORDS)

There is increasing evidence for a central role in mammalian apoptosis of the interleukin-1 beta-converting enzyme (ICE) family of cysteine proteases, homologues of the product of the nematode "death" gene, ced-3. Ced-3 is thought to act as an executor rather than a regulator of programmed cell death in the nematode. However, it is not known whether mammalian ICE-related proteases (IRPs) are involved in the execution or the regulation of mammalian apoptosis. Moreover, an absolute requirement for one or more IRPs for mammalian apoptosis has yet to be established. We have used two cell-permeable inhibitors of IRPs, Z-Val-Ala-Asp.fluoromethylketone (ZVAD.fmk) and t-butoxy carbonyl-Asp.fluoromethylketone (BD.fmk), to demonstrate a critical role for IRPs in mammalian apoptosis induced by several disparate mechanisms (deregulated oncogene expression, ectopic expression of the Bcl-2 relative Bak, and DNA damage-induced cell death). In all instances, ZVAD.fmk and BD.fmk treatment inhibits characteristic biochemical and morphological events associated with apoptosis, including cleavage of nuclear lamins and poly-(ADP-ribose) polymerase, chromatin condensation and nucleosome laddering, and external display of phosphatidylserine. However, neither ZVAD.fmk nor BD.fmk inhibits the onset of apoptosis, as characterized by the onset of surface blebbing; rather, both act to delay completion of the program once initiated. In complete contrast, IGF-I and Bcl-2 delay the onset of apoptosis but have no effect on the kinetics of the program once initiated. Our data indicate that IRPs constitute part of the execution machinery of mammalian apoptosis induced by deregulated oncogenes, DNA damage, or Bak but that they act after the point at which cells become committed to apoptosis or can be rescued by survival factors. Moreover, all such blocked cells have lost proliferative potential and all eventually die by a process involving cytoplasmic blebbing.

In a number of experimental systems, the early stage of the apoptotic process, i.e., the stage that precedes nuclear disintegration, is characterized by the breakdown of the inner mitochondrial transmembrane potential (delta psi m). This delta psi m disruption is mediated by the opening of permeability transition (PT) pores and appears to be critical for the apoptotic cascade, since it is directly regulated by Bcl-2 and since mitochondria induced to undergo PT in vitro become capable of inducing nuclear chromatinolysis in a cell-free system of apoptosis. Here, we addressed the question of which apoptotic events are secondary to mitochondrial PT. We tested the effect of a specific inhibitor of PT, bongkrekic acid (BA), a ligand of the mitochondrial adenine nucleotide translocator, on a prototypic model of apoptosis glucocorticoid-induced thymocyte death. In addition to abolishing the apoptotic delta psi m disruption, BA prevents a number of phenomena linked to apoptosis: depletion of nonoxidized glutathione, generation of reactive oxygen species, translocation of NF kappa B, exposure of phosphatidylserine residues on the outer plasma membrane, cytoplasmic vacuolization, chromatin condensation, and oligonucleosomal DNA fragmentation. BA is also an efficient inhibitor of p53-dependent thymocyte apoptosis induced by DNA damage. These data suggest that a number of apoptotic phenomena are secondary to PT. In addition, we present data indicating that apoptotic delta psi m disruption is secondary to transcriptional events. These data connect the PT control point to the p53- and ICE/ Ced 3-regulated control points of apoptosis and place PT upstream of nuclear and plasma membrane features of PCD.

Horizontal gene transfer contributes to the evolution of bacterial species. Mobile genetic elements play an important role in horizontal gene transfer, and characterization of the regulation of these elements should provide insight into conditions that influence bacterial evolution. We characterized a mobile genetic element, ICEBs1, in the Gram-positive bacterium Bacillus subtilis and found that it is a functional integrative and conjugative element (ICE) capable of transferring to Bacillus and Listeria species. We identified two conditions that promote ICEBs1 transfer: conditions that induce the global DNA damage response and crowding by potential recipients that lack ICEBs1. Transfer of ICEBs1 into cells that already contain the element is inhibited by an intercellular signaling peptide encoded by ICEBs1. The dual regulation of ICEBs1 allows for passive propagation in the host cell until either the potential mating partners lacking ICEBs1 are present or the host cell is in distress.

A ubiquitous characteristic of elderly and patients with gait disabilities is that they walk slower than healthy controls. Many clinicians assume these patients walk slower to improve their stability, just as healthy people slow down when walking across ice. However, walking slower also leads to greater variability, which is often assumed to imply deteriorated stability. If this were true, then slowing down would be completely antithetical to the goal of maintaining stability. This study sought to resolve this paradox by directly quantifying the sensitivity of the locomotor system to local perturbations that are manifested as natural kinematic variability. Eleven young healthy subjects walked on a motorized treadmill at five different speeds. Three-dimensional movements of a single marker placed over the first thoracic vertebra were recorded during continuous walking. Mean stride-to-stride standard deviations and maximum finite-time Lyapunov exponents were computed for each time series to quantify the variability and local dynamic stability, respectively, of these movements. Quadratic regression analyses of the dependent measures vs. walking speed revealed highly significant U shaped trends for all three mean standard deviations, but highly significant linear trends, with significant or nearly significant quadratic terms, for five of the six finite-time Lyapunov exponents. Subjects exhibited consistently better local dynamic stability at slower speeds for these five measures. These results support the clinically based intuition that people who are at increased risk of falling walk slower to improve their stability, even at the cost of increased variability.

Laser-capture microdissection (LCM) allows for the one-step procurement of large homogeneous populations of cells from tissue sections. In mammals, LCM has been used to conduct cDNA microarray and proteomics studies on specific cell types. However, LCM has not been applied to plant cells, most likely because plant cell walls make it difficult to separate target cells from surrounding cells and because ice crystals can form in the air spaces between cells when preparing frozen sections. By fixing tissues, using a cryoprotectant before freezing, and using an adhesive-coated slide system, it was possible to capture large numbers (>10,000) of epidermal cells and vascular tissues (vascular bundles and bundle sheath cells) from ethanol:acetic acid-fixed coleoptiles of maize. RNA extracted from these cells was amplified with T7 RNA polymerase and used to hybridize a microarray containing approximately 8800 maize cDNAs. Approximately 250 of these were expressed preferentially in epidermal cells or vascular tissues. These results demonstrate that the combination of LCM and microarrays makes it feasible to conduct high-resolution global gene expression analyses of plants. This approach has the potential to enhance our understanding of diverse plant cell type-specific biological processes.

BACKGROUND

There is little evidence supporting current safety recommendations for adolescent pitchers.

OBJECTIVE

Pitching practices of adolescent pitchers without history of arm injury will be significantly different from those of adolescent pitchers who required shoulder or elbow surgery.

METHODS

Case control study; Level of evidence, 3.

METHODS

Ninety-five adolescent pitchers who had shoulder or elbow surgery and 45 adolescent pitchers who never had a significant pitching-related injury completed a survey. Responses were compared between the 2 groups using t tests and chi(2) analyses. Multivariable logistic regression models were developed to identify the risk factors.

RESULTS

The injured group pitched significantly more months per year, games per year, innings per game, pitches per game, pitches per year, and warm-up pitches before a game. These pitchers were more frequently starting pitchers, pitched in more showcases, pitched with higher velocity, and pitched more often with arm pain and fatigue. They also used anti-inflammatory drugs and ice more frequently to prevent an injury. Although the groups were age matched, the injured group was taller and heavier. There were no significant differences regarding private pitching instruction, coach's chief concern, pitcher's self-rating, exercise programs, stretching practices, relieving frequency, pitch type frequency, or age at which pitch types were first thrown.

CONCLUSIONS

Pitching practices were significantly different between the groups. The factors with the strongest associations with injury were overuse and fatigue. High pitch velocity and participation in showcases were also associated with increased risk for injury.

CONCLUSIONS

New recommendations were made based on these results. Adherence to the recommendations may reduce the incidence of significant injury to adolescent pitchers.

The survival of various cells subjected to low temperature exposure is higher when they are cooled slowly. This increase is consistent with the view that slow cooling decreases the probability of intracellular freezing by permitting water to leave the cell rapidly enough to keep the protoplasm at its freezing point. The present study derives a quantitative relation between the amount of water in a cell and temperature. The relation is a differential equation involving cooling rate, surface-volume ratio, membrane permeability to water, and the temperature coefficient of the permeability constant. Numerical solutions to this equation give calculated water contents which permit predictions as to the likelihood of intracellular ice formation. Both the calculated water contents and the predictions on internal freezing are consistent with the experimental observations of several investigators.

Although proteases related to the interleukin 1 beta-converting enzyme (ICE) are known to be essential for apoptotic execution, the number of enzymes involved, their substrate specificities, and their specific roles in the characteristic biochemical and morphological changes of apoptosis are currently unknown. These questions were addressed using cloned recombinant ICE-related proteases (IRPs) and a cell-free model system for apoptosis (S/M extracts). First, we compared the substrate specificities of two recombinant human IRPs, CPP32 and Mch2 alpha. Both enzymes cleaved poly-(ADP-ribose) polymerase, albeit with different efficiencies. Mch2 alpha also cleaved recombinant and nuclear lamin A at a conserved VEID decreases NG sequence located in the middle of the coiled-coil rod domain, producing a fragment that was indistinguishable from the lamin A fragment observed in S/M extracts and in apoptotic cells. In contrast, CPP32 did not cleave lamin A. The cleavage of lamin A by Mch2 alpha and by S/M extracts was inhibited by millimolar concentrations of Zn2+, which had a minimal effect on cleavage of poly (ADP-ribose) polymerase by CPP32 and by S/M extracts. We also found that N-(acetyltyrosinylvalinyl-N epsilon-biotinyllysyl)aspartic acid [(2,6-dimethylbenzoyl)oxy]methyl ketone, which derivatizes the larger subunit of active ICE, can affinity label up to five active IRPs in S/M extracts. Together, these observations indicate that the processing of nuclear proteins in apoptosis involves multiple IRPs having distinct preferences for their apoptosis-associated substrates.

Chromosome 8p22-p11 has been identified as a locus for schizophrenia in several genome-wide scans and confirmed by meta-analysis of published linkage data. Systematic fine mapping using extended Icelandic pedigrees identified an associated haplotype in the gene neuregulin 1 (NRG1), also known as heuregulin, glial growth factor, NDF43 and ARIA. A 290 kb core at risk haplotype at the 5' end of the gene (HAP(ICE)), defined by five SNPs and two microsatellite polymorphisms was found to be associated with schizophrenia in the Icelandic and Scottish populations. A number of subsequent independent studies have attempted to replicate the association, and while some have been successful, the associated haplotype is not always HAP(ICE). Furthermore, no obviously functional or pathogenic variants have been identified, and the relationship between the gene and schizophrenia has remained inconclusive. To reconcile these conflicting findings and to give a comprehensive picture of the genetic architecture of this important gene, we performed a meta-analysis of 13 published population-based and family-based association studies up to November 2005. We analysed data from the SNP markers SNP8NRG241930, SNP8NRG243177, SNP8NRG221132 and SNP8NRG221533, and the microsatellite markers 478B14-848, 420M9-1395. Across these studies, strong positive association was found for all six polymorphisms. The haplotype analysis also showed significant association in the pooled international populations (OR=1.22, 95% CI 1.15-1.3, P=8 x 10(-10)). In Asian populations, the risk haplotype was focused around the two microsatellite markers, 478B14-848, 420M9-1395 (haplotype block B), and in Caucasian populations with the remaining four SNP markers (haplotype block A). This meta-analysis supports the involvement of NRG1 in the pathogenesis of schizophrenia, but with association between two different but adjacent haplotypes blocks in the Caucasian and Asian populations.

A procedure is described for isolating cell membranes from rat liver homogenates. 20 gm. of rat liver was homogenized in a Dounce homogenizer in ice cold water buffered to pH 7.5 with NaHCO(3), rupturing all of the cells and most nuclei. The diluted homogenate was filtered through cheesecloth to remove precipitated nucleoprotein and centrifuged at 1500 g, 10 minutes, to sediment a crude membrane fraction. The membrane containing sediment was recentrifuged 3 times in conical tubes (1220 g, 10 minutes), the top layer of the 2-layered sediment being retained. Flotation in a sucrose solution d = 1.22 freed the preparation from contaminating cell fragments and nuclear membranes not previously disintegrated. The floating material approximately 0.4 ml. was quite homogeneous and consisted of thin amorphous membranes. Electron micrographs revealed numerous double profiles similar in shape and dimensions to apposed liver cell membranes in intact tissue.

The severity of damaging human-induced climate change depends not only on the magnitude of the change but also on the potential for irreversibility. This paper shows that the climate change that takes place due to increases in carbon dioxide concentration is largely irreversible for 1,000 years after emissions stop. Following cessation of emissions, removal of atmospheric carbon dioxide decreases radiative forcing, but is largely compensated by slower loss of heat to the ocean, so that atmospheric temperatures do not drop significantly for at least 1,000 years. Among illustrative irreversible impacts that should be expected if atmospheric carbon dioxide concentrations increase from current levels near 385 parts per million by volume (ppmv) to a peak of 450-600 ppmv over the coming century are irreversible dry-season rainfall reductions in several regions comparable to those of the "dust bowl" era and inexorable sea level rise. Thermal expansion of the warming ocean provides a conservative lower limit to irreversible global average sea level rise of at least 0.4-1.0 m if 21st century CO(2) concentrations exceed 600 ppmv and 0.6-1.9 m for peak CO(2) concentrations exceeding approximately 1,000 ppmv. Additional contributions from glaciers and ice sheet contributions to future sea level rise are uncertain but may equal or exceed several meters over the next millennium or longer.

The distinction between model and nonmodel organisms is becoming increasingly blurred. High-throughput, second-generation sequencing approaches are being applied to organisms based on their interesting ecological, physiological, developmental, or evolutionary properties and not on the depth of genetic information available for them. Here, we illustrate this point using a low-cost, efficient technique to determine the fine-scale phylogenetic relationships among recently diverged populations in a species. This application of restriction site-associated DNA tags (RAD tags) reveals previously unresolved genetic structure and direction of evolution in the pitcher plant mosquito, Wyeomyia smithii, from a southern Appalachian Mountain refugium following recession of the Laurentide Ice Sheet at 22,000-19,000 B.P. The RAD tag method can be used to identify detailed patterns of phylogeography in any organism regardless of existing genomic data, and, more broadly, to identify incipient speciation and genome-wide variation in natural populations in general.