The concept of violent suicide,its underlying trait and neurobiology: A critical perspective

Suicide is one of the leading causes of death and represents a significant public health problem world-wide. Individuals who attempt or die by suicide represent a highly heterogeneous population. Recently, efforts have been made to identify sub-populations and variables to categorize them. A popular dichotomy in suicide research of the past years is violent versus non-violent suicide - based on the method. This dichotomy is important given that there is an association between method of attempted suicide and risk of subsequent death by suicide. The differentiation concerning suicide methods is also critical regarding preventive efforts. In this review, we have tried to approach the concept of violent suicide from different perspectives, including a discussion about its definition and overlapping categories. In addition, we have critically discussed aggression as underlying trait, the question of intent to die, and sociodemographic, environmental, neuropsychological, and neurobiological factors potentially associated with violent suicide.     

Psychosocial work environment of hospital workers: validation of a comprehensive assessment scale

BACKGROUND: Studies have shown that adverse workplace factors can increase the risk of ill-health in hospital workers, but more comprehensive measures of the psychosocial work environment are needed. OBJECTIVES: To test a comprehensive and theory-based psychosocial work environment questionnaire and analyze associations with mental health in a sample of Danish hospital workers. DESIGN AND PARTICIPANTS: Questionnaire-based cross-sectional study with 343 female employees from a large Danish hospital, including patient care workers (nurses, nurse assistants, midwives) and laboratory technicians. METHODS: The psychosocial work environment was measured with 14 scales from the Copenhagen psychosocial questionnaire, version I, covering three main areas: demands at work, work organization and interpersonal relations at work. We further measured self-rated mental health and sociodemographic and employment characteristics of the participants. Cronbach's alphas, analyses of covariance, one-sample t-tests, partial correlations and linear regression models were used to analyze data. RESULTS: Of the 14 work psychosocial workplace scales 12 showed a satisfactory internal consistency (alpha>0.70). Patient care workers had more quantitative, emotional and cognitive demands (all p-values <0.001), higher work pace (p<0.001) and more role conflicts (p=0.01) than laboratory technicians, but also better work organization, including more influence at work, better possibilities for development and a higher meaning of work (all p-values <0.001). Both patient care workers and laboratory technicians had substantially higher scores on the demand scales and lower scores on the influence at work scale than the general Danish working population. Further analyses showed that high levels of demands at work and low levels of work organization and problematic interpersonal relations at work were associated with lower self-rated mental health. CONCLUSION: The Copenhagen psychosocial questionnaire is a suitable instrument to measure the psychosocial work environment of hospital workers. The comprehensive assessment of the psychosocial work environment helps tailoring interventions to the specific needs of different occupational groups.     

Patterns of concurrent alcohol,tobacco, and cannabis use in Germany: Prevalence and correlates

Aims: This study investigated past month patterns and risk factors of alcohol, tobacco and cannabis use by level of intensity in the German general population.

Methods: Data from the 2006 German Epidemiological Survey of Substance Abuse (ESA) were used. The cross-sectional random sample consisted of N?=?7912 adults aged 18–64 years. The response rate was 45%. Intensive use of each substance was measured applying substance-specific cut-off points: alcohol: >20/30?g pure ethanol daily for women/men; tobacco: ≥20 cigarettes daily; cannabis: on ≥6 occasions monthly.

Findings: The majority of substance users reported no intensive use of any of the three substances (77.5%) and 19.4% had used one of the three substances intensively. A total of 3.1% engaged in intensive use of multiple substances with alcohol and tobacco (2.3%) as the most prevalent pattern. A higher risk for intensive use of multiple substances was found among males, older individuals and those with a substance use disorder.

Conclusions: Results of this study call for an integrated view on substance use and related disorders in prevention and treatment, taking diverse use patterns and specific needs of substance abusers into account.     

The proteome of Saccharomyces cerevisiae mitochondria

We performed a comprehensive approach to determine the proteome of Saccharomyces cerevisiae mitochondria. The proteins of highly pure yeast mitochondria were separated by several independent methods and analyzed by tandem MS. From >20 million MS spectra, 750 different proteins were identified, indicating an involvement of mitochondria in numerous cellular processes. All known components of the oxidative phosphorylation machinery, the tricarboxylic acid cycle, and the stable mitochondria-encoded proteins were found. Based on the mitochondrial proteins described in the literature so far, we calculate that the identified proteins represent approximately 90% of all mitochondrial proteins. The function of a quarter of the identified proteins is unknown. The mitochondrial proteome will provide an important database for the analysis of new mitochondrial and mitochondria-associated functions and the characterization of mitochondrial diseases.     

Antiviral immune responses in gene-targeted mice expressing the immunoglobulin heavy chain of virus-neutralizing antibodies

Two gene-targeted immunoglobulin heavy chain transgenic mouse strains, TgH(KL25) and TgH(VI10), expressing neutralizing specificities for lymphocytic choriomeningitis virus and vesicular stomatitis virus, respectively, have been generated. Three days after lymphocytic choriomeningitis virus infection, TgH(KL25) mice showed a thymus-independent neutralizing IgM response followed by thymus-dependent (TD) IgG. In contrast, WT mice mounted only a TD IgG response around day 80. These observations indicated that not only structural properties of the virus but also immunological parameters such as the frequency of B cells were indicative for the induction of thymus-independent versus TD Ig responses. Na?ve vesicular stomatitis virusspecific Ig heavy chain transgenic mice displayed greatly elevated natural antibody titers. However, despite these high na?ve titers, de novo activation of na?ve CD4+ T and B cells was not blocked. Therefore, B cells giving rise to natural antibodies do not participate in virus-induced antibody responses.     

Novel features in the genetic code and codon reading patterns in Neurospora crassa mitochondria based on sequences of six mitochondrial tRNAs

We report the sequences of Neurospora crassa mitochondrial alanine, leucine₁, leucine₂, threonine, tryptophan, and valine tRNAs. On the basis of the anticodon sequences of these tRNAs and of a glutamine tRNA, whose sequence analysis is nearly complete, we infer the following: (i) The N. crassa mitochondrial tRNA species for alanine, leucine₂, threonine, and valine, amino acids that belong to four-codon families (GCN, CUN, ACN, and GUN, respectively; N = U, C, A, or G) all contain an unmodified U in the first position of the anticodon. In contrast, tRNA species for glutamine, leucine₁, and tryptophan, amino acids that use codons ending in purines (CA_G^A, UU_G^A, and UG_G^A, respectively) contain a modified U derivative in the same position. These findings and the fact that we have not detected any other isoacceptor tRNAs for these amino acids suggest that N. crassa mitochondrial tRNAs containing U in the first position of the anticodon are capable of reading all four codons of a four-codon family whereas those containing a modified U are restricted to reading codons ending in A or G. Such an expanded codon-reading ability of certain mitochondrial tRNAs will explain how the mitochondrial protein-synthesizing system operates with a much lower number of tRNA species than do systems present in prokaryotes or in eukaryotic cytoplasm. (ii) The anticodon sequence of the N. crassa mitochondrial tryptophan tRNA is U^*CA and not CCA or CmCA as is the case with tryptophan tRNAs from prokaryotes or from eukaryotic cytoplasm. Because a tRNA with U^*CA in the anti-codon would be expected to read the codon UGA, as well as the normal tryptophan codon UGG, this suggests that in N. crassa mitochondria, as in yeast and in human mitochondria, UGA is a codon for tryptophan and not a signal for chain termination. (iii) The anticodon sequences of the two leucine tRNAs indicate that N. crassa mitochondria use both families of leucine codons (UU_A^G and CUN; N = U, C, A, or G) for leucine, in contrast to yeast mitochondria [Li, M. & Tzagoloff, A. (1979) Cell 18, 47-53] in which the CUA leucine codon and possibly the entire CUN family of leucine codons may be translated as threonine.