Autonomous model protocell division driven by molecular replication.

The coupling of compartmentalisation with molecular replication is thought to be crucial for the emergence of the first evolvable chemical systems. Minimal artificial replicators have been designed based on molecular recognition, inspired by the template copying of DNA, but none yet have been coupled to compartmentalisation. Here, we present an oil-in-water droplet system comprising an amphiphilic imine dissolved in chloroform that catalyses its own formation by bringing together a hydrophilic and a hydrophobic precursor, which leads to repeated droplet division. We demonstrate that the presence of the amphiphilic replicator, by lowering the interfacial tension between droplets of the reaction mixture and the aqueous phase, causes them to divide. Periodic sampling by a droplet-robot demonstrates that the extent of fission is increased as the reaction progresses, producing more compartments with increased self-replication. This bridges a divide, showing how replication at the molecular level can be used to drive macroscale droplet fission.Coupling compartmentalisation and molecular replication is essential for the development of evolving chemical systems. Here the authors show an oil-in-water droplet containing a self-replicating amphiphilic imine that can undergo repeated droplet division.

Metabolic plasticity in CLL: adaptation to the hypoxic niche.

Metabolic transformation in cancer is increasingly well understood. However, little is known about the metabolic responses of cancer cells that permit their survival in different microenvironments. We have used a nuclear magnetic resonance based approach to monitor metabolism in living primary chronic lymphoid leukemia (CLL) cells and to interrogate their real-time metabolic responses to hypoxia. Our studies demonstrate considerable metabolic plasticity in CLL cells. Despite being in oxygenated blood, circulating CLL cells are primed for hypoxia as measured by constitutively low level hypoxia-inducible factor (HIF-1α) activity and modest lactate production from glycolysis. Upon entry to hypoxia we observed rapid upregulation of metabolic rates. CLL cells that had adapted to hypoxia returned to the 'primed' state when re-oxygenated and again showed the same adaptive response upon secondary exposure to hypoxia. We also observed HIF-1α independent differential utilization of pyruvate in oxygenated and hypoxic conditions. When oxygenated, CLL cells released pyruvate, but in hypoxia imported pyruvate to protect against hypoxia-associated oxidative stress. Finally, we identified a marked association of slower resting glucose and glutamine consumption, and lower alanine and lactate production with Binet A0 stage samples indicating that CLL may be divided into tumors with higher and lower metabolic states that reflect disease stage.

Problems of HRQL assessment: how much is too much?

Few investigations have explored the extent to which a number of less serious problems contribute to health-related quality of life (HRQL) impairment beyond a smaller number of more serious problems. Our study examined the relative impact of the number and severity of patient problems on HRQL. This study analyzed results from 100 patients with irritable bowel syndrome (IBS) and 100 women with polycystic ovary syndrome (PCOS). We compared an aggregation method that generated scores using all items that could affect HRQL as the denominator (all items) to a second method that considered only items that patients experienced as problems (problem items). For each IBS and PCOS questionnaire domain, we used regression analysis to examine the relative contribution of scores from the all-items and problem-items approaches to prediction of scores on the other instruments. Of 57 correlations between IBS domains and scores on the other questionnaires, the all-items method explained a statistically significant additional proportion of the variance beyond the problem items in 29 cases and the problem items a significant additional proportion of the variance between the all items in 7 (p < 0.001). Of the 28 correlations between the PCOS and the other questionnaires, the all-items approach explained a significant additional proportion of the variance in 21 cases and the problem items approach in 5 (p < 0.001). With IBS and PCOS, including all potential items in calculating a domain score provided a more accurate portrayal of HRQL than a selected approach focusing on problem items

Stroke in relation to cardiac procedures in patients with non-ST-elevation acute coronary syndrome: a study involving >18 000 patients.

BACKGROUND: There are few published data on risk factors for stroke in patients with non-ST-elevation acute coronary syndrome (ACS). We investigated prognostic factors for stroke in 2 large cohorts of patients from the Organization to Assess Strategies for Ischemic Syndromes (OASIS) registry (8010) and the OASIS-2 trial (10 141). METHODS AND RESULTS: A total of 18 151 patients with non-ST-elevation ACS were enrolled in the OASIS program. Data from these 2 studies were pooled (a test for heterogeneity was nonsignificant, P=0.34). Overall, 238 patients (1.3%) had a stroke over a 6-month follow-up. Those who experienced stroke had a 4-fold increase in 6-month mortality (27.0% versus 6.3%, P<0.001). A Cox multivariate regression analysis identified CABG surgery as the most important predictor of stroke (hazard ratio [HR], 4.6), followed by history of stroke (HR, 2.3), diabetes mellitus (HR, 1.7), older age (HR, 1.6 per 10-year increase), higher heart rate (HR, 1.1 per 10-bpm increase), and on-site catheterization facility (HR, 1.4). There was no significant excess in stroke in patients undergoing percutaneous coronary intervention (P=0.21). Patients who underwent early CABG surgery were at a substantially increased risk compared with those who had later CABG (3.3% versus 1.6%; HR, 2.1; P=0.003) or who had no surgery (3.3% versus 1.1%; HR, 3.95; P=0.0001). CONCLUSIONS: In this large cohort of patients with ACS, stroke was an uncommon but serious event associated with high mortality. The performance of early CABG surgery was a powerful independent predictor of stroke.

Syntheses and structures of M(L)(X)BPh4 complexes (M = Co(II), Zn(II); L = cis-1,3,5-tris[3-(2-furyl)prop-2-enylideneamino]cyclohexane, X = OAc, NO3) n: structural models of the active site of carbonic anhydrase.

The metal coordination geometries in the structures of the zinc(II) and cobalt(II) complexes of the ligand cis-1,3,5-tris[3-(2-furyl)prop-2-enylideneamino]cyclohexane (fr-protach) and with the anions nitrate and acetate are structural models for the active site of carbonic anhydrase. The acetate structures show a striking structural correlation with the metal coordination environments in the known bicarbonate forms of the enzyme. Such structures provide a basis for understanding the marked effect of different metal substitution on the catalytic rate of the enzyme.

Previous exposure to Chlamydia pneumoniae, Helicobacter pylori and other infections in Canadian patients with ischemic heart disease.

OBJECTIVE: Previous exposures to Chlamydia pneumoniae (CP), Helicobacter pylori (HP) or cytomegalovirus (CMV) have been associated with atherosclerotic heart disease. These associations were studied in Canadian patients, and the exposure to five infections measured. DESIGN: Case-control study. SETTING: In the coronary care units (Hamilton General site, Henderson General site, McMaster University Medical Centre site of the Hamilton Health Sciences Corporation and St Joseph's Hospital) and from the regional angiography suite (Hamilton General site), Hamilton, Ontario. PATIENTS AND METHODS: One hundred seven consecutive patients presenting with myocardial infarction or unstable angina (coronary care unit patients), or with previous angina or myocardial infarction (angiography suite patients), were compared with 107 family practice or outpatient clinic control subjects. INTERVENTIONS: Cardiovascular risk factors were measured, as was serology for CP, HP, CMV, adenovirus and hepatitis A virus. Statistical analysis was by logistic regression, adjusted for age and sex. RESULTS: Exposure to CP was more frequent in patients than in control subjects (85.4% versus 70.3%, adjusted odds ratio [OR] 2.3, 95% CI 1.1 to 5.1, P=0.03). Dividing CP immunoglobulin G absorbance into quarters, with the lowest quarter as the reference group, the adjusted ORs were 2.8, 3.0 and 4.3, respectively, for the second, third and fourth quarters (P=0.001 for trend). The seroprevalences of HP (61.7%), CMV (64.0%), adenovirus (75.6%) and hepatitis A virus (59.2%) were high, with no association with disease. CONCLUSIONS: An association was found between heart disease and previous exposure to CP, with a stepwise increase in ORs at higher antibody levels, whereas no association was found with HP, CMV or other infections. A prospective validation of this association is needed.

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 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.

Development of a health-related quality-of-life questionnaire (PCOSQ) for women with polycystic ovary syndrome (PCOS).

OBJECTIVE: To develop a self-administered questionnaire for measuring health-related quality of life (HRQL) in women with polycystic ovary syndrome (PCOS). METHODS: We identified a pool of 182 items potentially relevant to women with PCOS through semistructured interviews with PCOS patients, a survey of health professionals who worked closely with PCOS women, and a literature review. One hundred women with PCOS completed a questionnaire in which they told us whether the 182 items were relevant to them and, if so, how important the issue was in their daily lives. We included items endorsed by at least 50% of women in the analysis plus additional items considered crucial by clinicians and an important subgroup of patients in a factor analysis. We chose items for the final questionnaire taking into account both item impact (the frequency and importance of the items) and the results of the factor analysis. RESULTS: Over 50% of the women with PCOS labelled 47 items as important to them. Clinicians chose 5 additional items from the infertility domain, 4 of which were identified as important by women who were younger, less educated, married, and African-American. The Cattell's Scree plot from a factor analysis of these 51 items suggested 5 factors that made intuitive sense: emotions, body hair, weight, infertility, and menstrual problems. We chose the highest impact items from these 5 domains to construct a final questionnaire, the Polycystic Ovary Syndrome Questionnaire (PCOSQ), which includes a total of 26 items and takes 10-15 minutes to complete. CONCLUSIONS: We have used established principles to construct a questionnaire that promises to be useful in measuring health-related quality of life. The questionnaire should be tested prior to, or concurrent with, its use in randomized trials of new treatment approaches.

Frequency and methodologic rigor of quality-of-life assessments in the critical care literature.

OBJECTIVES: To present a framework for describing/measuring quality of life (QOL) and health-related quality of life (HRQL), and to assess the frequency and methodologic rigor of QOL studies in the adult critical care literature. DATA SOURCES: Computerized bibliographic search of published research, manual search of key intensive care unit (ICU) journals, and citation review of relevant articles. STUDY SELECTION: We manually searched Critical Care Medicine, American Journal of Respiratory and Critical Care Medicine, and Intensive Care Medicine for the period January 1992 to July 1995 to assess the frequency of published QOL studies. Combined with a computerized bibliographic search, we found 64 studies that met our criteria that reported on patient-related outcomes (other than mortality) after hospital discharge. DATA EXTRACTION: We abstracted data on the nature of each study, the instruments used to measure QOL, and the methodologic rigor of the QOL assessments. We evaluated each study using criteria we developed to assess the validity of HRQL measurements. MEASUREMENTS AND MAIN RESULTS: In our manual search, we found 1,073 articles relevant to the practice of adult critical care. Of these, 19 (1.7%)/1073 included QOL measurements. Combined with our comprehensive search strategy, we found 64 papers that evaluated QOL in ICU patients. These papers dealt primarily with issues of: prognosis (32 [50%]), resource allocation (23 [36%]), and clinical prediction (9 [14%]). We found no randomized trials that included post-ICU QOL as an outcome. With respect to the validity of the HRQL assessments, 63/64 (98%) studies evaluated aspects of patients' lives that we considered important. Thirty-three (52%) studies were limited in scope to specific aspects of HRQL, and 31 (48%) studies covered broad areas of HRQL. In these 64 studies, there were 108 different instruments used. The reliability and validity of the instruments used were reported in 7 (6%) and 15 (14%) cases, respectively. For 81 (75%) instruments, the investigators either explained the results or used informative, qualitative descriptors whose interpretation was self-evident. Overall, three (5%) of the included studies met all four methodologic criteria to assess the validity of HRQL assessments. CONCLUSIONS: QOL assessments occur infrequently in the ICU literature and are of limited methodologic quality. More studies using valid and reliable instruments are necessary to document the long-term QOL of critically ill patients, especially those at risk of a "poor" outcome.

Corticosteroid treatment for sepsis: a critical appraisal and meta-analysis of the literature.

OBJECTIVE: To determine the effect of corticosteroid therapy on morbidity and mortality in patients with sepsis. DATA SOURCES: We searched for published and unpublished research using MEDLINE, EMBASE, and the Science Citation Index, manual searching of Index Medicus, citation review of relevant primary and review articles, personal files, and contact with primary investigators. STUDY SELECTION: From a pool of 124 potentially relevant articles, duplicate independent review identified nine relevant, randomized, controlled trials of corticosteroid therapy in sepsis and septic shock among critically ill adults. DATA EXTRACTION: In duplicate, independently, we abstracted key data on population, intervention, outcome, and methodologic quality of the randomized controlled trials. DATA SYNTHESIS: Corticosteroids appear to increase mortality in patients with overwhelming infection (relative risk 1.13, 95% confidence interval 0.99 to 1.29), and have no beneficial effect in the subgroup of patients with septic shock (relative risk 1.07, 95% confidence interval 0.91 to 1.26). Studies with the highest methodologic quality scores also suggest a trend toward increased mortality overall (relative risk 1.10, 95% confidence interval 0.94 to 1.29). A similar trend was observed for patients with septic shock (relative risk 1.12, 95% confidence interval 0.95 to 1.32). No difference in secondary infection rates was demonstrated in corticosteroid-treated patients with sepsis or septic shock. However, there was a trend toward increased mortality from secondary infections in patients receiving corticosteroids (relative risk 1.70, 95% confidence interval 0.70 to 4.12). The occurrence rate of gastrointestinal bleeding was increased slightly in the treatment group (relative risk 1.17, 95% confidence interval 0.79 to 1.73). CONCLUSIONS: Current evidence provides no support for the use of corticosteroids in patients with sepsis or septic shock, and suggests that their use may be harmful. These trials underscore the need for future methodologically rigorous trials evaluating new immune-modulating therapies in well-defined critically ill patients with overwhelming infection.