[Development and validation of the Subclinical Stress Symptom Questionnaire SSQ-25]. / Entwicklung und Validierung des Subklinischen Stresssymptom-Questionnaire SSQ-25.

BACKGROUND: Stress symptoms are widespread in the general population and often occur in the early course of mental disorders. However, no validated instrument was available for the study of subclinical stress symptoms and their relevance in the study of psychopathological trajectories. In order to advance and systematize the study of the etiology and pathogenesis of diseases in subclinical populations, the Subclinical Stress Symptom Questionnaire (SSQ-25) was developed in the present study. METHODS: In the course of three online studies, a total of 1174 subjects were recruited. The first study included item selection and the development of the questionnaire based on the analysis of item parameters, reliability, and exploratory factor analysis. To validate the factor structure, confirmatory factor analysis was used. Validation analyses were applied to distinguish the SSQ-25 from three clinical measures: Beck's Anxiety and Depression Inventory (BAI and BDI), and the Posttraumatic Stress Diagnostic Scale (PDS). In the third study the subclinical property of the instrument was investigated. RESULTS: Exploratory and confirmatory factor analyses revealed and confirmed a two-factor model (psychological and physiological stress symptoms). Cronbach's alpha was 0.95. The subclinical property of the SSQ-25 was confirmed by means of item information functions, scatter plots, residuals, and Koenker-Bassett tests as opposed to established clinical measures. DISCUSSION: The SSQ-25 is a comprehensive, reliable, and valid instrument that allows a valid assessment and differentiation of subclinical stress symptoms.

An Experimental Platform Generating Simulated Blunt Impacts to the Head Due to Rearward Falls.

Impacts to the back of the head due to rearward falls, also referred to as "backfall" events, represent a common source of TBI for athletes and soldiers. A new experimental apparatus is described for replicating the linear and rotational kinematics of the head during backfall events. An anthropomorphic test device (ATD) with a head-borne sensor suite was configured to fall backwards from a standing height, inducing contact between the rear of the head and a ground surface simulant. A pivoting swing arm and release strap were used to generate consistent and realistic head kinematics. Backfall experiments were performed with the ATD fitted with an American football helmet and the resulting linear and rotational head kinematics, as well as calculated injury metrics, compared favorably with those of football players undergoing similar impacts during games or play reconstructions. This test method complements existing blunt impact helmet performance experiments, such as drop tower and pneumatic ram test methods, which may not be able to fully reproduce head-neck-torso kinematics during a backfall event.

Impact of nitric oxide on metabolism in health and age-related disease.

Nitric oxide (NO) serves as a messenger molecule in a variety of physiological systems and also converts into toxic radical species that can damage cells through a process known as nitrosative stress. While the physiological roles of NO in blood vessel dilation, the nervous system and the immune system are well established, recent studies have begun to investigate the role of NO in metabolism and energy expenditure through modulation of mitochondria. NO appears to stimulate mitochondrial biogenesis in certain situations through activation of proteins such as peroxisome proliferator-activated receptor γ (PPARγ) co-activator 1α (PGC1-α). Because of this link between NO and mitochondrial biogenesis, the role of NO in certain aspects of metabolism, including exercise response, obesity, fat cell differentiation and caloric restriction, are the subject of increasing investigation. In addition to its role in mitochondrial biogenesis, NO also stimulates mitochondrial fragmentation, which can be caused by too much mitochondrial fission or inhibition of mitochondrial fusion and can result in bioenergetic failure. While the contribution of NO-mediated mitochondrial fragmentation to neurodegenerative diseases seems clear, the mechanisms by which NO causes fragmentation are uncertain and controversial. In this review, we discuss the role of NO in manipulation of mitochondrial biogenesis and dynamics and how these events contribute to human health- and age-related disease.

Preservation of mitochondrial structure and function after Bid- or Bax-mediated cytochrome c release.

Proapoptotic members of the Bcl-2 protein family, including Bid and Bax, can activate apoptosis by directly interacting with mitochondria to cause cytochrome c translocation from the intermembrane space into the cytoplasm, thereby triggering Apaf-1-mediated caspase activation. Under some circumstances, when caspase activation is blocked, cells can recover from cytochrome c translocation; this suggests that apoptotic mitochondria may not always suffer catastrophic damage arising from the process of cytochrome c release. We now show that recombinant Bid and Bax cause complete cytochrome c loss from isolated mitochondria in vitro, but preserve the ultrastructure and protein import function of mitochondria, which depend on inner membrane polarization. We also demonstrate that, if caspases are inhibited, mitochondrial protein import function is retained in UV-irradiated or staurosporine-treated cells, despite the complete translocation of cytochrome c. Thus, Bid and Bax act only on the outer membrane, and lesions in the inner membrane occurring during apoptosis are shown to be secondary caspase-dependent events.

The pro-apoptotic proteins, Bid and Bax, cause a limited permeabilization of the mitochondrial outer membrane that is enhanced by cytosol.

During apoptosis, an important pathway leading to caspase activation involves the release of cytochrome c from the intermembrane space of mitochondria. Using a cell-free system based on Xenopus egg extracts, we examined changes in the outer mitochondrial membrane accompanying cytochrome c efflux. The pro-apoptotic proteins, Bid and Bax, as well as factors present in Xenopus egg cytosol, each induced cytochrome c release when incubated with isolated mitochondria. These factors caused a permeabilization of the outer membrane that allowed the corelease of multiple intermembrane space proteins: cytochrome c, adenylate kinase and sulfite oxidase. The efflux process is thus nonspecific. None of the cytochrome c-releasing factors caused detectable mitochondrial swelling, arguing that matrix swelling is not required for outer membrane permeability in this system. Bid and Bax caused complete release of cytochrome c but only a limited permeabilization of the outer membrane, as measured by the accessibility of inner membrane-associated respiratory complexes III and IV to exogenously added cytochrome c. However, outer membrane permeability was strikingly increased by a macromolecular cytosolic factor, termed PEF (permeability enhancing factor). We hypothesize that PEF activity could help determine whether cells can recover from mitochondrial cytochrome c release.

Changes in endoplasmic reticulum luminal environment affect cell sensitivity to apoptosis.

To test the role of ER luminal environment in apoptosis, we generated HeLa cell lines inducible with respect to calreticulin and calnexin and investigated their sensitivity to drug-dependent apoptosis. Overexpression of calreticulin, an ER luminal protein, resulted in an increased sensitivity of the cells to both thapsigargin- and staurosporine-induced apoptosis. This correlated with an increased release of cytochrome c from the mitochondria. Overexpression of calnexin, an integral ER membrane protein, had no significant effect on drug-induced apoptosis. In contrast, calreticulin-deficient cells were significantly resistant to apoptosis and this resistance correlated with a decreased release of cytochrome c from mitochondria and low levels of caspase 3 activity. This work indicates that changes in the lumen of the ER amplify the release of cytochrome c from mitochondria, and increase caspase activity, during drug-induced apoptosis. There may be communication between the ER and mitochondria, which may involve Ca(2+) and play an important role in conferring cell sensitivity to apoptosis. Apoptosis may depend on both the presence of external apoptosis-activating signals, and, as shown in this study, on an internal factor represented by the ER.

The release of cytochrome c from mitochondria: a primary site for Bcl-2 regulation of apoptosis.

In a cell-free apoptosis system, mitochondria spontaneously released cytochrome c, which activated DEVD-specific caspases, leading to fodrin cleavage and apoptotic nuclear morphology. Bcl-2 acted in situ on mitochondria to prevent the release of cytochrome c and thus caspase activation. During apoptosis in intact cells, cytochrome c translocation was similarly blocked by Bcl-2 but not by a caspase inhibitor, zVAD-fmk. In vitro, exogenous cytochrome c bypassed the inhibitory effect of Bcl-2. Cytochrome c release was unaccompanied by changes in mitochondrial membrane potential. Thus, Bcl-2 acts to inhibit cytochrome c translocation, thereby blocking caspase activation and the apoptotic process.

The Tingathe Surge: a multi-strategy approach to accelerate HIV case finding in Malawi.

SETTING: Nineteen health facilities in rural, southeastern Malawi. OBJECTIVE: To describe the implementation and results of a 6-week intervention to accelerate human immunodeficiency virus (HIV) case finding. DESIGN: Six HIV testing strategies were simultaneously implemented. Routinely collected data from Ministry of Health registers were used to determine the number of HIV tests performed and of new cases identified. The weekly averages of the total number of tests and new cases before and during the intervention were compared. Testing by age group and sex was described. The percentage yield of new cases was compared by testing strategy. RESULTS: Of 29 703 HIV tests conducted, 1106 (3.7%) were positive. Of the total number of persons tested, 69.5% were women and 75.5% were aged >15 years. The yield of positive test results was 3.5% among women, 4.3% among men, 4.4% among those aged >15 years and 1.5% among those aged ⩽15 years. The average weekly number of tests increased 106.7% from 3337 to 6896 (P = 0.002). The average weekly number of positive cases identified increased 51.9% from 158 to 240 (P = 0.017). The testing strategy with the highest yield resulted in a 6.0% yield; the lowest was 1.3%. The yield for all strategies, except one, was highest in adult men. CONCLUSION: A multi-strategy approach to HIV testing and counseling can be an effective means of accelerating HIV case finding.

Mitochondrial fission is an upstream and required event for bax foci formation in response to nitric oxide in cortical neurons.

Mitochondrial dysfunction is an underpinning event in many neurodegenerative disorders. Less clear, however, is how mitochondria become injured during neuronal demise. Nitric oxide (NO) evokes rapid mitochondrial fission in cortical neurons. Interestingly, proapoptotic Bax relocates from the cytoplasm into large foci on mitochondrial scission sites in response to nitrosative stress. Antiapoptotic Bcl-xL does not prevent mitochondrial fission despite its ability to block Bax puncta formation on mitochondria and to mitigate neuronal cell death. Mitofusin 1 (Mfn1) or dominant-negative dynamin-related protein 1(K38A) (Drp1(k38A)) inhibits mitochondrial fission and Bax accumulation on mitochondria induced by exposure to an NO donor. Although NO is known to cause a bioenergetic crisis, lowering ATP by glycolytic or mitochondrial inhibitors neither induces mitochondrial fission nor Bax foci formation on mitochondria. Taken together, these data indicate that the mitochondrial fission machinery acts upstream of the Bcl-2 family of proteins in neurons challenged with nitrosative stress.

Designing molecular structure to achieve ductile fracture behavior in a stiff and strong 2D polymer, "graphylene".

As the simplest two-dimensional (2D) polymer, graphene has immensely high intrinsic strength and elastic stiffness but has limited toughness due to brittle fracture. We use atomistic simulations to explore a new class of graphene/polyethylene hybrid 2D polymer, "graphylene", that exhibits ductile fracture mechanisms and has a higher fracture toughness and flaw tolerance than graphene. A specific configuration of this 2D polymer hybrid, denoted "GrE-2" for the two-carbon-long ethylene chains connecting benzene rings in the inherent framework, is prioritized for study. MD simulations of crack propagation show that the energy release rate to propagate a crack in GrE-2 is twice that of graphene. We also demonstrate that GrE-2 exhibits delocalized failure and other energy-dissipating fracture mechanisms such as crack branching and bridging. These results demonstrate that 2D polymers can be uniquely tailored to achieve a balance of fracture toughness with mechanical stiffness and strength.

[Importance of the Watzke-Allen test in diagnostics and staging of macular holes]. / Bedeutung des Watzke-Allen-Tests in der Diagnostik und Stadieneinteilung von Makulaforamina.

BACKGROUND: The Watzke-Allen test (WAT) is a simple diagnostic tool designed for the diagnosis of full thickness macular holes (FTMH) but due to the rapid progress of imaging diagnostics it was replaced by spectral domain optical coherence tomography (SD-OCT) of macular pathologies. The aim of this study was to examine if the WAT is able to distinguish between the different FTMH stages. METHODS: In 57 eyes of 57 patients with clinical evidance of FTMH, the WAT was first performed followed by SD-OCT examination and a distinction was made between a negative (slit beam normal) and a positive sign (slit beam modified as groove and hourglass configuration or completely broken). RESULTS: In 49 out of 57 patients the WAT was positive (hourglass 46 patients and broken 3 patients). Based on the SD-OCT results the following diagnoses were made: lamellar macular holes (LMH, 3 patients), vitreomacular traction (VMT, 4 patients), small macular hole (≤ 250 µm, 5 patients), medium sized macular hole (250-400 µm, 11 patients) and large macular hole (≥ 400 µm, 34 patients). In 91 % of the patients with medium and large FTMH, the WAT was positive, whereas the WAT was positive in only 67 % of patients with small FTMH, VMT and LMH. The sensitivity for large and medium FTMH was 93 % but the specificity was only 33 %. CONCLUSION: The WAT was positive in a high percentage of patients with large and medium sized macular holes as well as patients with small macular holes and LMH. The sensitivity of certain indications for treatment was 93 % but the specificity was only 33 %; therefore, the WAT alone is not suitable for a certain preoperative differentiation of macular alterations.

Caspase 7 can cleave tumor necrosis factor receptor-I (p60) at a non-consensus motif, in vitro.

Ligand binding to tumor necrosis factor receptor-I (TNFRI) can promote cell survival or activate the apoptotic caspase cascade. Cytoplasmic interaction of TNFRI with TRAF2 and RIP allows for the activation of JNK and NFkappaB pathways. Alternatively, a carboxy terminal death domain protein interaction motif can recruit TRADD, which then recruits FADD/MORT1, and finally procaspase 8. Aggregation of these components form a death inducing signaling complex, leading to the cleavage and activation of caspase 8. We have found that during apoptosis human TNFRI protein is lost in a caspase-dependent manner. The cytoplasmic tail of human TNFRI was found to be susceptible to caspase cleavage but not by caspase 8. Instead, the downstream executioner caspase 7 was the only caspase capable of cleaving TNFRI, in vitro. Identification and characterization of the cleavage site revealed a derivative of the classic EXD motif that incorporates a glutamate (E) in the P1 position. Using several criteria to establish that caspase activity was responsible for cleavage at this site, we confirmed that caspase 7 can cleave at a GELE motif. Mutation of the cleavage site prevented the apoptosis-associated cleavage of TNFRI. This ability of caspase 7 to cleave at a non-EXD or -DXXD motif suggests that the specificity of caspases may be broader than is currently held.

Bcl-xL does not inhibit the function of Apaf-1.

Bcl-2 and its relative, Bcl-xL, inhibit apoptotic cell death primarily by controlling the activation of caspase proteases. Previous reports have suggested at least two distinct mechanisms: Bcl-2 and Bcl-xL may inhibit either the formation of the cytochrome c/Apaf-1/caspase-9 apoptosome complex (by preventing cytochrome c release from mitochondria) or the function of this apoptosome (through a direct interaction of Bcl-2 or Bcl-xL with Apaf-1). To evaluate this latter possibility, we added recombinant Bcl-xL protein to cell-free apoptotic systems derived from Jurkat cells and Xenopus eggs. At low concentrations (50 nM), Bcl-xL was able to block the release of cytochrome c from mitochondria. However, although Bcl-xL did associate with Apaf-1, it was unable to inhibit caspase activation induced by the addition of cytochrome c, even at much higher concentrations (1-5 microM). These observations, together with previous results obtained with Bcl-2, argue that Bcl-xL and Bcl-2 cannot block the apoptosome-mediated activation of caspase-9.

Primary cilia and autophagic dysfunction in Huntington's disease.

Huntington's disease (HD) is an inherited, neurodegenerative disorder caused by a single-gene mutation: a CAG expansion in the huntingtin (HTT) gene that results in production of a mutated protein, mutant HTT, with a polyglutamine tail (polyQ-HTT). Although the molecular pathways of polyQ-HTT toxicity are not fully understood, because protein misfolding and aggregation are central features of HD, it has long been suspected that cellular housekeeping processes such as autophagy might be important to disease pathology. Indeed, multiple lines of research have identified abnormal autophagy in HD, characterized generally by increased autophagic induction and inefficient clearance of substrates. To date, the origin of autophagic dysfunction in HD remains unclear and the search for actors involved continues. To that end, recent studies have suggested a bidirectional relationship between autophagy and primary cilia, signaling organelles of most mammalian cells. Interestingly, primary cilia structure is defective in HD, suggesting a potential link between autophagic dysfunction, primary cilia and HD pathogenesis. In addition, because polyQ-HTT also accumulates in primary cilia, the possibility exists that primary cilia might play additional roles in HD: perhaps by disrupting signaling pathways or acting as a reservoir for secretion and propagation of toxic, misfolded polyQ-HTT fragments. Here, we review recent research suggesting potential links between autophagy, primary cilia and HD and speculate on possible pathogenic mechanisms and future directions for the field.

Effects of long-term treatment with 120 mg of sustained-release isosorbide dinitrate and 60 mg of sustained-release nifedipine on myocardial perfusion.

Forty patients with coronary artery disease and scintigraphically proven myocardial ischemia were randomized into 2 groups receiving 4 weeks of treatment with either 120 mg of isosorbide dinitrate (ISDN) release or 60 mg of nifedipine release. Control exercise testing and myocardial scintigraphy were continued until anginal pains occurred, and repeated at identical individual workloads at the end of the 4 weeks of drug therapy. Myocardial scintigrams were evaluated by quantitative recording of counts in 60 segments/frame. Twenty patients in the ISDN group (group I) exhibited 47 significantly ischemic areas. The remaining 20 patients (group II), treated with nifedipine, had 50 ischemic areas before therapy. In the ischemic areas in group I, there was a mean difference of 30.9% between counts at rest and during exercise in the pretreatment period, and a difference of 18.1% after therapy (39.0%). In group II, the pretreatment difference was 28.8%, decreasing to 20.6% after therapy (17.8%). Both groups of patients were subsequently subdivided into 3 subsets: (1) significantly improved perfusion, (2) significant worsening, and (3) unchanged myocardial perfusion. Group I had 59.5% of areas with significant improvement and 10.6% of areas with significant worsening. In 29.7% of the areas, the findings were unchanged. Group II had improvement in 40% of areas, of significantly worsened areas in 6%, and unchanged areas in 54%, in both groups myocardial ischemia was reduced by therapy, but ISDN improved myocardial perfusion to a considerably greater extent than did nifedipine.

Chlorate poisoning: mechanism of toxicity.

Intoxications with chlorate salts are characterized by methaemoglobin formation, haemolysis and renal insufficiency. The toxic effects on the erythrocyte can be reproduced in vitro. Incubation of human and rabbit erythrocytes with chlorates induces a concentration-dependent oxidation of haemoglobin. This methaemoglobin formation is followed by denaturation of the globin, a cross-linking of erythrocyte membrane proteins and an inactivation of membrane enzymes. The high sensitivity of glucose-6-phosphate dehydrogenase to denaturation by chlorate explains the inefficacy of methylene blue to reduce methaemoglobin formed, as the antidotal effect of methylene blue depends on NADPH formed mainly by the oxidation of glucose-6-phosphate. The observed changes occur only in the presence of methaemoglobin which forms a destabilising complex with chlorate. Methaemoglobin thus autocatalytically increases methaemoglobin formation and destruction of the erythrocyte. As the rabbit is known to have a high methaemoglobin-reduction capacity, human and rabbit erythrocytes were compared. In vitro, the rabbit erythrocyte is less sensitive to oxidative attack than the human red cell. In vivo, an oral dose of sodium chlorate (1 g/kg body wt.) resulted in high serum (16 +/- 4 mM) and urine concentrations (246 +/- 99 mM) in the rabbit. Methaemoglobin was not formed nor could a nephrotoxic effect be observed. These experiments also indicate that the nephrotoxicity of chlorate is mediated by methaemoglobin catalysis.

Erythrocyte membrane alterations as the basis of chlorate toxicity.

The effects of sodium chlorate and of sodium nitrite on human erythrocytes were studied in vitro. Nitrite rapidly oxidised haemoglobin and glutathione; reduction of methaemoglobin (Hbi) by methylene blue was complete during 3 h of incubation with nitrite. With chlorate, a concentration-dependent lag phase was seen before Hbi was formed. After prolonged incubation, Hbi could no longer be reduced with methylene blue. Several other effects were observed that explain the clinical picture of chlorate poisoning which involves haemolysis followed by disseminated intravascular coagulation and renal failure: increased permeability to cations, increased resistance to hypotonic haemolysis and prolonged filtration time through polycarbonate membranes with cylindrical pores of 5 micron diameter. This suggests an increased membrane rigidity due to membrane protein polymerisation, as demonstrated by SDS polyacrylamide gel electrophoresis. Simultaneously, erythrocyte enzymes were inactivated, primarily glucose-6-phosphate dehydrogenase which is necessary for the therapeutic effect of methylene blue. This explains the inefficacy of methylene blue in the treatment of a case of chlorate poisoning that we observed (Arch. Toxicol., 48 (1981) 281).

Apoptosis: checkpoint at the mitochondrial frontier.

Apoptosis, an evolutionarily conserved form of cell death, requires a regulated program. Central to the apoptotic program is a family of cysteine proteases, known as caspases, that cleave a subset of cellular proteins, resulting in the stereotypic morphological changes of apoptotic cell death. In living cells caspases are present as inactive zymogens and become activated in response to pro-apoptotic stimuli. Mitochondria participate in the activation of caspases by releasing cytochrome c into the cytosol where it binds to the adaptor molecule Apaf-1 (apoptotic protease activating factor 1) and causes its oligomerization. This renders Apaf-1 competent to recruit and activate the cell death initiator caspase, pro-caspase-9. Once caspase-9 is activated, it cleaves and activates downstream cell death effector caspases. Bcl-2, an apoptosis inhibitor localized to mitochondrial outer membranes, prevents cytochrome c release, caspase activation and cell death. This review discusses recent advances on the role of mitochondria and cytochrome c in the central pathway leading to apoptotic cell death.

[The radiologic picture of bronchopulmonary aspergillosis]. / Zum radiologischen Bild der bronchopulmonalen Aspergillose.

The increasing incidence of conditions associated with immune suppression, either as part of the illness or as the result of treatment, makes it necessary to investigate the possibility of fungus infections whenever there are broncho-pulmonary changes. In this respect, aspergillus is a common infection which produces more or less typical radiological changes. It often requires a variety of radiological procedures, including the use of CT and nuclear medicine. The latter can be useful in the allergic form of aspergillosis used for ventilation scintigraphy. The possibility of aspergillosis must be brought to the attention of the clinicians by the radiologist, even in cases that are not entirely typical.

["Cold lesions" in bone scintigraphy (author's transl)]. / "Cold lesions" in der Knochenszintigraphie.

Frequency and location of "cold lesions" has been analysed in 1000 consecutive bone scans. Among the 554 abnormal cases there were 18 (1,8% of the total) with localized diminished activity due to metastatic lesions and 5 (0,5%) secondary to radiation osteitis. 10 of the 18 patients with metastatic disease had pure defects while 8 showed a reactive margin. It is pointed out that the quality of the examination is crucial for the demonstration of such defects and that single scans of the different regions of the skeleton are superior to a whole body scan. The survey of the literature shows that "cold lesions" are predominant in malignant bone diseases, however no relation exists to a definite histology.