Nuclear release of eIF1 globally increases stringency of start-codon selection to preserve mitotic arrest physiology.

Regulated start-codon selection has the potential to reshape the proteome through the differential production of uORFs, canonical proteins, and alternative translational isoforms. However, conditions under which start-codon selection is altered remain poorly defined. Here, using transcriptome-wide translation initiation site profiling, we reveal a global increase in the stringency of start-codon selection during mammalian mitosis. Low-efficiency initiation sites are preferentially repressed in mitosis, resulting in pervasive changes in the translation of thousands of start sites and their corresponding protein products. This increased stringency of start-codon selection during mitosis results from increased interactions between the key regulator of start-codon selection, eIF1, and the 40S ribosome. We find that increased eIF1-40S ribosome interactions during mitosis are mediated by the release of a nuclear pool of eIF1 upon nuclear envelope breakdown. Selectively depleting the nuclear pool of eIF1 eliminates the changes to translational stringency during mitosis, resulting in altered mitotic proteome composition. In addition, preventing mitotic translational rewiring results in substantially increased cell death and decreased mitotic slippage following treatment with anti-mitotic chemotherapeutics. Thus, cells globally control translation initiation stringency with critical roles during the mammalian cell cycle to preserve mitotic cell physiology.

Molecular density-accelerated binding-site maturation underlies CENP-T-dependent kinetochore assembly.

Formation of macromolecular cellular structures relies on recruitment of multiple proteins, requiring the precisely controlled pairwise binding interactions. At human kinetochores, our recent work found that the high molecular density environment enables strong bonding between the Ndc80 complex and its two binding sites at the CENP-T receptor. However, the mechanistic basis for this unusual density-dependent facilitation remains unknown. Here, using quantitative single-molecule approaches, we reveal two distinct mechanisms that drive preferential recruitment of the Ndc80 complex to higher-order structures of CENP-T, as opposed to CENP-T monomers. First, the Ndc80 binding sites within the disordered tail of the CENP-T mature over time, leading to a stronger grip on the Spc24/25 heads of the Ndc80 complexes. Second, the maturation of Ndc80 binding sites is accelerated when CENP-T molecules are clustered in close proximity. The rates of the clustering-induced maturation are remarkably different for two binding sites within CENP-T, correlating with different interfaces formed by the corresponding CENP-T sequences as they wrap around the Spc24/25 heads. The differential clustering-dependent regulation of these sites is preserved in dividing human cells, suggesting a distinct regulatory entry point to control kinetochore-microtubule interactions. The tunable acceleration of slowly maturing binding sites by a high molecular-density environment may represent a fundamental physicochemical mechanism to assist the assembly of mitotic kinetochores and other macromolecular structures.

Higher-order protein assembly controls kinetochore formation.

To faithfully segregate chromosomes during vertebrate mitosis, kinetochore-microtubule interactions must be restricted to a single site on each chromosome. Prior work on pair-wise kinetochore protein interactions has been unable to identify the mechanisms that prevent outer kinetochore formation in regions with a low density of CENP-A nucleosomes. To investigate the impact of higher-order assembly on kinetochore formation, we generated oligomers of the inner kinetochore protein CENP-T using two distinct, genetically engineered systems in human cells. Although individual CENP-T molecules interact poorly with outer kinetochore proteins, oligomers that mimic centromeric CENP-T density trigger the robust formation of functional, cytoplasmic kinetochore-like particles. Both in cells and in vitro, each molecule of oligomerized CENP-T recruits substantially higher levels of outer kinetochore components than monomeric CENP-T molecules. Our work suggests that the density dependence of CENP-T restricts outer kinetochore recruitment to centromeres, where densely packed CENP-A recruits a high local concentration of inner kinetochore proteins.

A bidirectional relationship between sleep and oxidative stress in Drosophila.

Although sleep appears to be broadly conserved in animals, the physiological functions of sleep remain unclear. In this study, we sought to identify a physiological defect common to a diverse group of short-sleeping Drosophila mutants, which might provide insight into the function and regulation of sleep. We found that these short-sleeping mutants share a common phenotype of sensitivity to acute oxidative stress, exhibiting shorter survival times than controls. We further showed that increasing sleep in wild-type flies using genetic or pharmacological approaches increases survival after oxidative challenge. Moreover, reducing oxidative stress in the neurons of wild-type flies by overexpression of antioxidant genes reduces the amount of sleep. Together, these results support the hypothesis that a key function of sleep is to defend against oxidative stress and also point to a reciprocal role for reactive oxygen species (ROS) in neurons in the regulation of sleep.

Non-steroidal anti-inflammatory drug-induced cardiovascular adverse events: a meta-analysis.

WHAT IS KNOWN AND OBJECTIVE: Although non-steroidal anti-inflammatory drugs (NSAIDs) have been studied in randomized, controlled trials and meta-analyses in an effort to determine their cardiovascular (CV) risks, no consensus has been reached. These studies continue to raise questions, including whether cyclooxygenase-2 (COX-2) selectivity plays a role in conferring CV risk. We performed a meta-analysis of current literature to determine whether COX-2 selectivity leads to an increased CV risk. METHODS: We utilized randomized, controlled trials and prospective cohort studies. We selected eight NSAIDs based on popularity and COX selectivity and conducted a search of the MEDLINE, EMBASE, and Cochrane databases. Primary endpoints included any myocardial infarction (MI), any stroke, CV death, and a combination of all three (composite CV outcomes). Twenty-six studies were found that met inclusion and exclusion criteria. Comparisons were made between all included drugs, against placebo, and against non-selective NSAIDs (nsNSAIDs). Drugs were also compared against COX-2 selective inhibitors (COXIBs) with and without inclusion of rofecoxib. RESULTS AND DISCUSSION: Incidence of MI was increased by rofecoxib in all comparison categories [all NSAIDs (OR: 1·811, 95% CI: 1·379-2·378), placebo (OR: 1·655: 95% CI: 1·029-2·661), nsNSAIDs (OR: 2·155, 95% CI: 1·146-4·053), and COXIBs (OR: 1·800, 95% CI: 1·217-2·662)], but was decreased by celecoxib and naproxen in the COXIB comparison [(OR: 0·583, 95% CI: 0·396-0·857) and (OR: 0·609, 95% CI: 0·375-0·989, respectively]. Incidence of stroke was increased by rofecoxib in comparisons with all NSAIDs and other COXIBs [(OR: 1·488, 95% CI: 1·027-2·155) and (OR: 1·933, 95% CI: 1·052-3·549), respectively]. Incidence of stroke was decreased by celecoxib when compared with all NSAIDs, nsNSAIDs, and COXIBs [(OR: 0·603, 95% CI: 0·410-0·887), (OR: 0·517, 95% CI: 0·287-0·929), and (OR: 0·509, 95% CI: 0·280-0·925), respectively]. No NSAID reached statistical significance in regard to CV death. Incidence of the composite endpoint was increased by rofecoxib when compared against all NSAIDs, placebo, and other COXIBs [(OR: 1·612, 95% CI: 1·313-1·981), (OR: 1·572, 95% CI: 1·123-2·201) and (OR: 1·838, 95% CI: 1·323-2·554), respectively]. Incidence of composite endpoint was decreased by celecoxib in the all NSAIDs and COXIBs comparisons [(OR: 0·805, 95% CI: 0·658-0·986) and (OR: 0·557, 95% CI: 0.404-0.767), respectively]. When rofecoxib was removed from the COXIBs group, no difference was found with any comparison, suggesting rofecoxib skewed the data. WHAT IS NEW AND CONCLUSION: This instead of the meta-analysis suggests that COX-2 selectivity may not play a role in the CV risk of NSAIDs. Rofecoxib was the only drug to demonstrate harm and skewed the data of the COX-2 selective group.

A retrospective study on the incidence and risk factors of severe hypoglycemia in primary care.

AIMS: To investigate the incidence and risk factors of severe hypoglycemia (SH) in primary care. SH was defined as hypoglycemia with coma, or the need of glucose or glucagon injection. METHODS: We performed a cross-sectional retrospective study in patients with diabetes treated in primary care in Germany. We analyzed an unselected sample of participants with type 1 (n = 373) and type 2 diabetes (n = 4481) who participated in an insurance plan from the health care insurer Deutsche BKK. Data of participants with type 1 diabetes are as follows: women, n = 155 (42%); age, 49±16 years; diabetes duration, 20+13 years; BMI, 28±6 kg/m2; GHb, 7.1+1.5%; GHb≤7%, n = 263 (71%); GHb≥8.5%, n = 48 (13%). Data of participants with type 2 diabetes: women, n = 1979 (44%); age, 66±10 years; diabetes duration, 8±7 years; BMI, 30±5 kg/m2; GHb, 6.6±1.3%; GHb≤7%, n = 3747 (84%); GHb≥8.5%, n = 360 (8%); insulin therapy, n = 1175 (26%). RESULTS: The incidence of SH in type 1 diabetes: 1.3% (CI: 0.4%, 3.1%) per year; type 2 diabetes with insulin therapy: 0.9% (CI: 0.5%, 1.7%); without insulin therapy: 0.3% (CI: 0.1%, 0.6%). The event rate was 0.02 SH per patient/year in type 1 diabetes and 0.01 in type 2 diabetes, respectively. Low BMI, GHb, insulin therapy and female gender were associated with an increased risk of SH. CONCLUSIONS: In primary care, patients with diabetes can achieve good glycemic control with very rare events of SH. Due to low incidence, SH would have been an inappropriate parameter to evaluate the outcome quality of diabetes therapy in primary care.

Obesity in the news: directions for future research.

Obesity attracts large volumes of news coverage. This in turn has spawned academic studies investigating how news framing may affect views about causes of and solutions to obesity. We use key studies to demonstrate that although existing research has made valuable discoveries about how obesity is defined in various media outlets, some methodological and theoretical questions remain unaddressed. We argue that extant research has focused on one dimension of analysis--the problematization of obesity in news stories--precluding insights into the entire process of obesity communication. Drawing on framing and media studies research, we propose a multidimensional approach to shed more light on factors affecting the production of obesity news stories by journalists and how they may be received by audience members. Ways of moving research into this multidimensional direction are proposed, including analysis of journalistic news values, political leaning and style of media outlets, emotion-eliciting language, readers' comments and obesity-related news visuals. Knowledge resulting from the exploration of these dimensions of the issue of obesity can be used to improve strategies to inform and engage audience members.

Structure of a Leu3-DNA complex: recognition of everted CGG half-sites by a Zn2Cys6 binuclear cluster protein.

Gal4 is the prototypical Zn2Cys6 binuclear cluster transcriptional regulator that binds as a homodimer to DNA containing inverted CGG half-sites. Leu3, a member of this protein family, binds to everted (opposite polarity to inverted) CGG half-sites, and an H50C mutation within the Leu3 Zn2Cys6 binuclear motif abolishes its transcriptional repression function without impairing DNA binding. We report the X-ray crystal structures of DNA complexes with Leu3 and Leu3(H50C) and solution DNA binding studies of selected Leu3 mutant proteins. These studies reveal the molecular details of everted CGG half-site recognition, and suggest a role for the H50C mutation in transcriptional repression. Comparison with the Gal4-DNA complex shows an unexpected conservation in the DNA recognition mode of inverted and everted CGG half-sites, and points to a critical function of a linker region between the Zn2Cys6 binuclear cluster and dimerization regions in DNA binding specificity. Broader implications of these findings are discussed.

Leucine biosynthesis in fungi: entering metabolism through the back door.

After exploring evolutionary aspects of branched-chain amino acid biosynthesis, the review focuses on the extended leucine biosynthetic pathway as it operates in Saccharomyces cerevisiae. First, the genes and enzymes specific for the leucine pathway are considered: LEU4 and LEU9 (encoding the alpha-isopropylmalate synthase isoenzymes), LEU1 (isopropylmalate isomerase), and LEU2 (beta-isopropylmalate dehydrogenase). Emphasis is given to the unusual distribution of the branched-chain amino acid pathway enzymes between mitochondrial matrix and cytosol, on the newly defined role of Leu5p, and on regulatory mechanisms governing gene expression and enzyme activity, including new evidence for the metabolic importance of the regulation of alpha-isopropylmalate synthase by coenzyme A. Next, structure-function relationships of the transcriptional regulator Leu3p are addressed, defining its dual role as activator and repressor and discussing evidence in support of the self-masking model. Recent data pointing at a more extended Leu3p regulon are discussed. An overview of the layered controls of the extended leucine pathway is provided that includes a description of the newly recognized roles of Ilv5p and Bat1p in maintaining mitochondrial integrity. Finally, branched-chain amino acid biosynthesis and its regulation in other fungi are summarized, the question of leucine as metabolic signal is addressed, and possible directions of future research in this area are outlined.

Racial differences in the incidence of gliomas: a retrospective study from Memphis, Tennessee.

This study records the incidence of glioblastoma multiforme, astrocytoma and oligodendroglioma in the white and Black patients in the Memphis Statistical Metropolitan Area (MSMA) during a 10.5-year period from 1 January 1984 through 30 June 1994. During this time, only six hospitals performed craniotomy and computer tomography (CT) scanning was routine in each of the hospitals. A total of 824 histologically confirmed first diagnoses were made at these six area hospitals. Based on the zip code listed as the home address, we determined patient's locale and identified 373 patients (232 glioblastoma multiforme, 106 astrocytomas and 35 oligodendroglioma) who resided in the area during the study interval. There were 50 black and 323 white patients. The background population for the area was obtained from the US Census Bureau's statistics for the year 1990. These statistics indicated that 40.5% of the population identified themselves as black and 57.9% as white. Age adjusted incidence rates were 1.550 (p < 0.001) for other astrocytomas, and 0.106 and 0.461 (p = 0.003) in the black and white populations, respectively. There was no significant difference in survival between the two populations. This study confirms a significant disparity in incidence rates for the three most common gliomas between the black and white populations and this disparity is higher than predicted by previous reports.

Prostaglandin production after experimental discectomy.

STUDY DESIGN: This study ascertained the effects of discectomy on prostaglandin synthesis. OBJECTIVES: The purpose of these novel experiments was to measure the levels of two prostaglandins in lumbar epidural fluid obtained from an area subjected to discectomy. For comparison, lumbar epidural fluid from a site not disturbed by discectomy and fluid from a subcutaneous site were analyzed for the prostaglandins. SUMMARY OF BACKGROUND DATA: Previous studies have shown that nuclear material obtained from degenerative discs manifests an extraordinarily high level of phospholipase A2 activity. Others have hypothesized that the known inflammatory effects of phospholipase A2 are due to the release of arachidonic acid, which is converted to various eicosanoids, including several algesic prostaglandins (PGI2 and PGE2). No previous study has continuously measured prostaglandin levels in epidural fluid or assessed the effect of discectomy on prostaglandin production. METHODS: An ultrafiltrate of lumbar epidural fluid of dogs was obtained from indwelling catheters located adjacent to spinal areas that were and were not subjected to discectomy as well as from subcutaneous tissue. The fluid was collected daily for 14 days and analyzed for PGE2 and 6-keto PGF1(alpha) (the stable metabolite of PGI2) by radioimmunoassay. RESULTS: The concentration of 6-keto PGF1(alpha) and PGE2 in fluid collected during the first 24 hours was significantly higher in the area of discectomy than in the epidural region that was not subjected to discectomy and significantly higher than in fluid obtained from the subcutaneous site. The high level of these prostaglandins at the discectomy site fell rapidly, so that by the end of 48 hours the differences in values between spinal fluid from the discectomy and nondiscectomy regions were not statistically significant. The concentration of the prostaglandins in epidural fluid decreased with time and became minimal within the second week. CONCLUSION: The removal of normal discs is accompanied for 24 hours by a marked rise in the synthesis of two prostaglandins known to produce pain. Because the concentration of prostaglandins in epidural fluid decreased rapidly thereafter, the initial surge obtained appears to be associated more with chemical factors such as phospholipase A2 than with wound healing.

Mammography in men.

PURPOSE: To evaluate mammographic findings in men with abnormality of the breast. MATERIALS AND METHODS: The most common indications for mammography, performed in 263 men (mean age, 62 years; range, 19-93 years), were breast tenderness in 88 men (33%) and palpable mass in 79 men (30%). All chief symptoms and all mammographic findings were categorized. Biopsy results were correlated with mammographic findings in 24 patients. Follow-up ranged from 6 months to 8 years 4 months (mean, 3 years 4 months). RESULTS: The most common mammographic finding was gynecomastia in 213 men (81%). Gynecomastia was unilateral or asymmetric in 168 men (72%). Biopsy results in 14 patients with gynecomastia were negative for cancer; the 199 other patients did not have cancer at follow-up. Six patients had breast cancer: Four had primary breast cancer, and two had metastases to the breast from extramammary malignancies. No cancer had the mammographic appearance of gynecomastia. None of the 43 patients younger than age 50 years had cancer. CONCLUSION: A man with breast enlargement or a palpable mass who has the mammographic diagnosis of gynecomastia need not undergo biopsy unless there are other strong clinical indications [corrected]. A man younger than age 50 years with diffuse breast enlargement or a palpable, nonindurated, central, subareolar mass need not undergo mammography unless there are other strong clinical indications.

Effects of a TV drama series upon public impressions about psychiatrists.

A survey was conducted among a nationally representative sample of over 2,800 UK television viewers to examine audience reactions towards a drama series about psychiatry. Whilst the majority of respondents agreed that the drama Shrinks was good entertainment and gave a realistic view of the field of psychiatry, those who reportedly had a close association with a mentally ill person were less likely to find the characterisations of the patients and psychiatrists credible. Despite the misgivings of practising psychiatrists and clinical psychologists, however, no evidence was found to support the idea that watching the drama resulted in misconceptions about the real world of psychiatric medicine.

The validity and significance of substages of advanced ovarian cancer.

No studies to date have evaluated the validity of the new FIGO substaging of advanced epithelial ovarian cancer nor assessed the importance of substage in relation to other elements such as age at diagnosis, debulking surgery, and second-look laparotomy. The purpose of this study was to determine the significance of these factors. One hundred sixty-seven patients with Stage III ovarian cancer were restaged according to the 1988 FIGO criteria (6% Stage IIIa, 15.6% Stage IIIb, and 78.4% Stage IIIc). The mean age at diagnosis was 40.5 for Stage IIIa, 51 for Stage IIIb, and 62 for Stage IIIc (P = 0.0001). Median survival was 2.5 years for patients age < 60 and 1.4 years for those age > or = 60 (P = 0.0001). Median survival for patients undergoing TAH/BSO was 2.06 years, bowel resection 1.39 years, and biopsy only 1.38 years (P = 0.0003). Only 61 of 131 Stage IIIc patients underwent second-look laparotomy. Seven of nine Stage IIIa, 6 of 17 Stage IIIb, and 14 of 61 Stage IIIc patients had negative second-look laparotomies (P = 0.004). Only 4 of the 14 patients with Stage IIIc and 8 of 13 Stage IIIa/b patients are alive after negative second look (P = 0.37). Median survival for Stage IIIa patients has not been reached and for Stages IIIb and IIIc was 2.29 years and 1.33 years, respectively (P = 0.0001). These data confirm the prognostic validity of FIGO substages for Stage III. The age differential by substages suggests that the natural history of Stage III disease is progressive over several decades. The appropriateness of aggressive cytoreductive surgery and second-look laparotomy must be reevaluated using the new FIGO staging system.

Media professionals' views of the government's 1987 AIDS campaign.

One hundred and twenty six journalists and programme-makers were interviewed to ascertain their views about the effectiveness of the Government's campaign in early 1987 to inform the public about the risks from Aids. The majority view was that it was a good all-round campaign focused on the public at large and on several at-risk groups. It was also thought to have been acceptable to the public. But a sizeable minority of media professionals felt that more selective targeting would have been desirable, and that the information was not specific enough. Another criticism concerned the lack of an adequate follow-up. There was general agreement that before the campaign the public knew little about Aids, and that afterwards they were better informed, in particular about the prevalence of Aids and the existence of high-risk groups. Overall, however, respondents underestimated the campaign's achievements in increasing knowledge, while overestimating changes in attitudes and behaviour. Recommendations were made about the format and content of TV programmes for future public information campaigns concerning AIDS.

Characterization of particleboard aerosol--size distribution and formaldehyde content.

Health hazards unique to particleboard include the generation of urea-formaldehyde resin bound in wood aerosol and release of formaldehyde gas that can be inhaled by the worker. A particleboard aerosol was generated by a sanding process and collected under laboratory conditions that determined the particle size distribution and formaldehyde content. Three side-by-side Marple 296 personal cascade impactors with midget impingers attached downstream collected particleboard aerosol and gaseous formaldehyde for ten sample runs. Gravimetric analysis quantified the collected aerosol mass, and chromotropic acid/spectrophotometric analytical methods were employed for formaldehyde content in particleboard aerosol and gaseous formaldehyde liberated from sanded particleboard. Significant variations (p less than .005) were observed for the particleboard mass and gaseous formaldehyde collected between sample runs. No significant differences (alpha = .05) were observed for the aerosol size distribution determined and formaldehyde content in particleboard aerosol per unit mass for sampling trials. The overall MMAD of particleboard aerosol was 8.26 microns AED with a sigma g of 2.01. A predictive model was derived for determining the expected formaldehyde content (microgram) by particleboard aerosol mass (mg) collected and particulate size (micron AED).

Health effects among refrigeration repair workers exposed to fluorocarbons.

Refrigeration repair workers may be intermittently exposed to fluorocarbons and their thermal decomposition products. A case of peripheral neuropathy (distal axonopathy) in a commercial refrigeration repairman prompted an epidemiological investigation of the health of refrigeration repair workers. No additional cases of peripheral neuropathy were identified among the 27 refrigeration repair workers studied. A reference group of 14 non-refrigeration repair workers was also studied. No differences were noted between groups for the ulnar (motor and sensory), median (motor and sensory), peroneal, sural, or tibial nerve conduction velocities. Refrigeration repair workers reported palpitations and lightheadedness significantly more often than workers in the reference group. No clinical neurological or electroneurophysiological abnormalities were detected in eight refrigeration repair workers followed up for three years during continuous employment.