Import of apocytochrome c into the mitochondrial intermembrane space along a cytochrome c1 sorting pathway

The question of whether cytochrome c could be functionally sorted to the mitochondrial intermembrane space along a "conservative sorting" pathway was investigated using a fusion protein termed pLc1-c. pLc1-c contains 3-fold targeting information, namely, the complete bipartite presequence of the cytochrome c1 precursor joined to the amino terminus of apocytochrome c. pLc1-c could be selectively imported into the intermembrane space either directly across the outer membrane along a cytochrome c import route or along a cytochrome c1 route via the matrix. Thus, apocytochrome c could be sorted along a conservative sorting pathway; however, following reexport from the matrix, apo-Lc1-c could not be converted to its holo counterpart. Despite the apparent similarity of structure and functional location of the heme lyases and similarity of the heme binding regions in their respective apoproteins, cytochrome c heme lyase and cytochrome c1 heme lyase apparently have different and nonoverlapping substrate specificities

Translocation arrest by reversible folding of a precursor protein imported into mitochondria

Passage of precursor proteins through translocation contact sites of mitochondria was investigated by studying the import of a fusion protein consisting of the NH2-terminal 167 amino acids of yeast cytochrome b2 precursor and the complete mouse dihydrofolate reductase. Isolated mitochondria of Neurospora crassa readily imported the fusion protein. In the presence of methotrexate import was halted and a stable intermediate spanning both mitochondrial membranes at translocation contact sites accumulated. The complete dihydrofolate reductase moiety in this intermediate was external to the outer membrane, and the 136 amino acid residues of the cytochrome b2 moiety remaining after cleavage by the matrix processing peptidase spanned both outer and inner membranes. Removal of methotrexate led to import of the intermediate retained at the contact site into the matrix. Thus unfolding at the surface of the outer mitochondrial membrane is a prerequisite for passage through translocation contact sites. The membrane-spanning intermediate was used to estimate the number of translocation sites. Saturation was reached at 70 pmol intermediate per milligram of mitochondrial protein. This amount of translocation intermediates was calculated to occupy approximately 1% of the total surface of the outer membrane. The morphometrically determined area of close contact between outer and inner membranes corresponded to approximately 7% of the total outer membrane surface. Accumulation of the intermediate inhibited the import of other precursor proteins suggesting that different precursor proteins are using common translocation contact sites. We conclude that the machinery for protein translocation into mitochondria is present at contact sites in limited number

Protein folding causes an arrest of preprotein translocation into mitochondria in vivo

With vital yeast cells, a hybrid protein consisting of the amino- terminal third of the precursor to cytochrome b2 and of the entire dihydrofolate reductase was arrested on the import pathway into mitochondria. Accumulation of the protein in the mitochondrial membranes was achieved by inducing a stable tertiary structure of the dihydrofolate reductase domain. Thereby, three salient features of mitochondrial protein uptake in vivo were demonstrated: its posttranslational character; the requirement for unfolding of precursors; and import through translocation contact sites. The permanent occupation of translocation sites by the fusion protein inhibited the import of other precursors; it did, however, not lead to leakage of mitochondrial ions, implying the existence of a channel that is sealed around the membrane spanning polypeptide segment

Disease prevention and health promotion programs: benefits, implementation, quality assurance and open questions - a summary of the evidence

Aim: Disease prevention and health promotion programs are standardized behavioral interventions that may be combined with contextual interventions. With optimized methods, they offer proven efficacy, efficiency, transparency, manageability, and rapid transfer of knowledge. Subject and methods: This review summarizes their central barriers and success factors based on current research. Results: Important barriers to effective use of disease prevention and health promotion programs are low implementation fidelity, exaggerated flexibility subject to political change, inadequately trained and overworked personnel, disregard of context, change of implementation frameworks, lack of supportive contextual interventions, a plethora of programs, scarce resources and weak organizational support, resistance to social technologies, choices based on marketing criteria instead of effectiveness, and research gaps. Solutions include robust intervention plans, clear and comprehensive manuals, definition of intervention core and periphery, organizational and leadership support, qualification of users, systematic adaptation to local conditions, and quality assurance/monitoring of acceptance and effectiveness. Conclusion: Both users and decision-makers should demand proof of effectiveness of program choices and should adhere to quality assurance procedures during implementation. Program development and evaluation should ensure (1) the definition of core intervention components, (2) instructions for adaptation of programs to specific contexts, (3) basic data on resources required for implementation, and (4) evidence of program effectiveness

Comparison of tools for assessing the methodological quality of primary and secondary studies in health technology assessment reports in Germany

Health care policy background: Findings from scientific studies form the basis for evidence-based health policy decisions. Scientific background: Quality assessments to evaluate the credibility of study results are an essential part of health technology assessment reports and systematic reviews. Quality assessment tools (QAT) for assessing the study quality examine to what extent study results are systematically distorted by confounding or bias (internal validity). The tools can be divided into checklists, scales and component ratings. Research questions: What QAT are available to assess the quality of interventional studies or studies in the field of health economics, how do they differ from each other and what conclusions can be drawn from these results for quality assessments? Methods: A systematic search of relevant databases from 1988 onwards is done, supplemented by screening of the references, of the HTA reports of the German Agency for Health Technology Assessment (DAHTA) and an internet search. The selection of relevant literature, the data extraction and the quality assessment are carried out by two independent reviewers. The substantive elements of the QAT are extracted using a modified criteria list consisting of items and domains specific to randomized trials, observational studies, diagnostic studies, systematic reviews and health economic studies. Based on the number of covered items and domains, more and less comprehensive QAT are distinguished. In order to exchange experiences regarding problems in the practical application of tools, a workshop is hosted. Results: A total of eight systematic methodological reviews is identified as well as 147 QAT: 15 for systematic reviews, 80 for randomized trials, 30 for observational studies, 17 for diagnostic studies and 22 for health economic studies. The tools vary considerably with regard to the content, the performance and quality of operationalisation. Some tools do not only include the items of internal validity but also the items of quality of reporting and external validity. No tool covers all elements or domains. Design-specific generic tools are presented, which cover most of the content criteria. Discussion: The evaluation of QAT by using content criteria is difficult, because there is no scientific consensus on the necessary elements of internal validity, and not all of the generally accepted elements are based on empirical evidence. Comparing QAT with regard to contents neglects the operationalisation of the respective parameters, for which the quality and precision are important for transparency, replicability, the correct assessment and interrater reliability. QAT, which mix items on the quality of reporting and internal validity, should be avoided. Conclusions: There are different, design-specific tools available which can be preferred for quality assessment, because of its wider coverage of substantive elements of internal validity. To minimise the subjectivity of the assessment, tools with a detailed and precise operationalisation of the individual elements should be applied. For health economic studies, tools should be developed and complemented with instructions, which define the appropriateness of the criteria. Further research is needed to identify study characteristics that influence the internal validity of studies

Interventions for increasing uptake in screening programmes

Introduction: Opportunities for the early detection of disease are not sufficiently being taken advantage of. Specific interventions could increase the uptake of prevention programmes. A comprehensive analysis of effectiveness and cost-effectiveness of these interventions with reference to Germany is still needed. Objectives: This report aimed to describe and assess interventions to increase uptake in primary and secondary prevention and to explore the assessment of their cost-effectiveness. Methods: 29 scientific databases were systematically searched in a wide strategy. Additional references were located from bibliographies. All published systematic reviews and primary studies were assessed for inclusion without language restrictions. Teams of two reviewers identified the literature, extracted data and assessed the quality of the publications independently. Results: Four HTA reports and 22 systematic reviews were identified for the medical evaluation covering a variety of interventions. The economic evaluation was based on two HTA-reports, one meta-analysis and 15 studies. The evidence was consistent for the effectiveness of invitations and reminders aimed at users, and for prompts aimed at health care professionals. These interventions were the most commonly analysed. (Financial) Incentives for users and professionals were identified in a small number of studies. Limited evidence was available for cost-effectiveness showing incremental costs for follow-up reminders and invitations by telephone. Evidence for ethical, social and legal aspects pointed to needs in vulnerable populations. Discussion: The material was heterogeneous regarding interventions used, study populations and settings. The majority of references originated from the United States and focused on secondary prevention. Approaching all target groups by invitations and reminders was recommended to increase uptake in prevention programmes in general. Conclusions: Further research should aim to focus on primary prevention. Future research should also focus on specific interventions aiming to include vulnerable target groups and individuals, who have not previously made use of opportunities for prevention

Forty-five minutes of physical activity at school each day? Curricular promotion of physical activity in grades one to four

Aim: According to the US Department of Health and Human Services (2008) and the World Health Organization (2008), regular physical activity is essential to the healthy development of children and contributes to the reduction of chronic diseases throughout their life span. However, coordinated comprehensive national and international programs to promote physical activity and sports participation are lacking. According to the German Sports Federation (2006), physical education (PE) classes at German schools are increasingly being canceled or taught outside the school. "fit for pisa" is a German intervention developed in response to the demand for scientific evaluation of interventions like daily physical education. Its goal is to provide quality management-secured, structured and standardized PE instruction by qualified instructors. Subjects and methods: The "fit for pisa" intervention has been implemented at five primary schools in Göttingen, Germany, since 2003. This daily physical education intervention is based on quality standards. At the five primary schools participating in "fit for pisa," students receive a supplementary 3 class hours of PE/week in addition to the mandatory 2 class hours/week for the entire school term. In other words, the children now receive one 45-min session of PE each school day. Daily physical education is now a part of their mandatory school curriculum. The curriculum content and teaching methods have been continuously developed and optimized based on the state guidelines for Lower Saxony. Results: Teacher training is held at the participating schools once a month to promote standardized implementation and quality management of the intervention program. Additional monthly meetings are held so that the teachers can discuss any problems, deviations or other issues occurring in the classes. Checklists are provided for the teachers and external trainers to document the content and objectives of each lesson. Supervisors evaluate the checklists at regular intervals. Using these instruments, the results of the 4-year intervention program were evaluated at the five participating primary schools. Conclusions: This study provides important data for recommendations to implement additional physical education in primary schools, for the corresponding quality assurance instruments and for the optimization of physical education guidelines for primary schools

Licit and illicit substance use patterns among university students in Germany using cluster analysis

Schilling L, Zeeb H, Pischke C, et al. Licit and illicit substance use patterns among university students in Germany using cluster analysis. SUBSTANCE ABUSE TREATMENT PREVENTION AND POLICY. 2017;12(1): 44.The use of multiple licit and illicit substances plays an important role in many university students' lives. Previous research on multiple substance use patterns of university students, however, often fails to examine use of different illicit substances and/or hookah. Our objective was to complement and advance the current knowledge about common consumption patterns regarding illicit substances and hookah use in this group. Students from eight German universities completed an online survey as part of the INSIST study ('INternet-based Social norms Intervention for the prevention of substance use among STudents') regarding their consumption of alcohol, tobacco, hookah, cannabis and other illicit substances. Cluster analysis identified distinct consumption patterns of concurrent and non-concurrent substance use and multinomial logistic regressions described key sociodemographic factors associated with these clusters. Six homogeneous groups were identified: 'Alcohol Abstainers' (10.8%), 'Drinkers Only' (48.2%), 'Drinkers and Cigarette Smokers' (14.6%), 'Cannabis and Licit Substance Users' (11.2%), 'Hookah Users with Co-Use' (9.8%) and 'Illicit Substance Users with Co-Use' (5.4%). Illicit substance use clustered with the consumption of alcohol, tobacco and cannabis. Hookah use was regularly associated with alcohol consumption, less commonly associated with tobacco or cannabis use and very rarely associated with use of other illicit substances. Individuals consuming licit and illicit substances or hookah were mostly male and lived together with other students. Characteristics such as the number of years an individual had spent studying at a university, subject of study, immigrant background and religious affiliation were less commonly associated with cluster membership. Although we found substance use patterns in our sample largely similar to previous reports, we identified an important subgroup of individuals using both illicit and licit substances. These individuals may benefit especially from targeted interventions that focus on modifying addictive behavior patterns

Translocation arrest by reversible folding of a precursor protein imported into mitochondria

Passage of precursor proteins through translocation contact sites of mitochondria was investigated by studying the import of a fusion protein consisting of the NH2-terminal 167 amino acids of yeast cytochrome b2 precursor and the complete mouse dihydrofolate reductase. Isolated mitochondria of Neurospora crassa readily imported the fusion protein. In the presence of methotrexate import was halted and a stable intermediate spanning both mitochondrial membranes at translocation contact sites accumulated. The complete dihydrofolate reductase moiety in this intermediate was external to the outer membrane, and the 136 amino acid residues of the cytochrome b2 moiety remaining after cleavage by the matrix processing peptidase spanned both outer and inner membranes. Removal of methotrexate led to import of the intermediate retained at the contact site into the matrix. Thus unfolding at the surface of the outer mitochondrial membrane is a prerequisite for passage through translocation contact sites. The membrane-spanning intermediate was used to estimate the number of translocation sites. Saturation was reached at 70 pmol intermediate per milligram of mitochondrial protein. This amount of translocation intermediates was calculated to occupy approximately 1% of the total surface of the outer membrane. The morphometrically determined area of close contact between outer and inner membranes corresponded to approximately 7% of the total outer membrane surface. Accumulation of the intermediate inhibited the import of other precursor proteins suggesting that different precursor proteins are using common translocation contact sites. We conclude that the machinery for protein translocation into mitochondria is present at contact sites in limited number