Two distinct steps of Bak regulation during apoptotic stress signaling: different roles of MEKK1 and JNK1

Stress-activated protein (SAP) kinases and the mitochondrial pro-apoptotic Bcl-2 protein Bak are important regulators of apoptosis. Reduced expression of Bak increases cellular resistance to the anticancer agent cisplatin, and we report here that mouse embryo fibroblasts deficient in the SAP kinase jnk1 are highly resistant to apoptosis induced by cisplatin. When human melanoma cells were treated with cisplatin, Bak function was found to be regulated in two distinct steps by two SAP kinases, MEKK1 and JNK1. The first of these steps involves MEKK1-controlled conformational activation of Bak. The second step leads to formation of 80-170 kDa Bak complexes correlating with apoptosis, and is controlled by JNK1. Inhibition of MEKK1 blocked the initial Bak conformational activation but did not block JNK1 activation, and deficiency in, or inhibition of, JNK1 did not prevent conformational activation of Bak. Furthermore, inducible expression of a constitutively active form of MEKK1 led to Bak conformational activation, but not to 80-170 kDa complexes. Consequently, apoptosis was delayed unless JNK was exogenously stimulated, indicating that Bak conformational activation is not necessarily an apoptotic marker. The two-step regulation of Bak revealed here may be important for tight control of mitochondrial factor release and apoptosis.     

Effect of the power Balance® band on static balance, hamstring flexibility, and arm strength in adults

The purpose of this study was to determine the effect of Power Balance? bands on strength, flexibility, and balance. Strength and flexibility were measured using the MicroFit system. Strength was measured via a bicep curl and flexibility via the sit-and-reach method. Balance was measured by the BIODEX System SD. There were 4 different conditions for the balance test: eyes open on a firm surface (EOFS), eyes closed on a firm surface (ECFS), eyes open on a foam surface (EOFoS), and eyes closed on a foam surface (ECFoS). There were 24 subjects in the study (10 men and 14 women). A counterbalance, double-blind, placebo, controlled within-subject design was used. Each of the subjects participated in 3 treatment sessions, consisting of Power Balance?, placebo band, and no band. An alpha level of p ≤ 0.05 was set a priori. There were no significant differences in strength, flexibility, or balance with regard to the treatments used. There was a significant difference between the conditions in the balance test (p = 0.000): EOFS (0.51), ECFS (0.68), EOFoS (0.99), and ECFoS (2.18); however, these were independent of the treatment conditions. The results indicate that the Power Balance? bands did not have an effect on strength, flexibility, or balance.     

Proenkephalin expression and enkephalin release are widely observed in non-neuronal tissues

Enkephalins are opioid peptides that are found at high levels in the brain and endocrine tissues. Studies have shown that enkephalins play an important role in behavior, pain, cardiac function, cellular growth, immunity, and ischemic tolerance. Our global hypothesis is that enkephalins are released from non-neuronal tissues in response to brief ischemia or exercise, and that this release contributes to cardioprotection. To identify tissues that could serve as potential sources of enkephalins, we used real-time PCR, Western blot analysis, ELISA, immunofluorescence microscopy, and ex vivo models of enkephalin release. We found widespread expression of preproenkephalin (pPENK) mRNA and production of the enkephalin precursor protein proenkephalin (PENK) in rat and mouse tissues, as well as in tissues and cells from humans and pigs. Immunofluorescence microscopy with anti-enkephalin antisera demonstrated immunoreactivity in rat tissues, including heart and skeletal muscle myocytes, intestinal and kidney epithelium, and intestinal smooth muscle cells. Finally, isolated tissue studies showed that heart, skeletal muscle, and intestine released enkephalins ex vivo. Together our studies indicate that multiple non-neuronal tissues produce PENK and release enkephalins. These data support the hypothesis that non-neuronal tissues could play a role in both local and systemic enkephalin-mediated effects.     

Effect of anaesthetics on the release of beta-endorphin-immunoreactivity in rat plasma

Analgesia and anaesthesia produced by fentanyl, urethane and ether, but not pentobarbital, occurred concomitantly with an increase in the concentration of plasma beta-endorphin like immunoreactivity (BEIR), probably of pituitary origin. This increase was not associated with significant changes in pituitary or brainstem beta-endorphin content. Pretreatment with naloxone caused a reduction in plasma BEIR increase following Hypnorm, ether and urethane; and in the analgesia following Hypnorm and urethane. Pentobarbital, alone or in combination with naloxone, did not increase the concentration of plasma beta-endorphin. These results may indicate participation of endogenous opioids in the mechanism of action of urethane.     

Psychometric Properties of the Multidimensional Health Locus of Control Scale Form C in a Non-Western Culture

Form C of the Multidimensional Health Locus of Control Scales (MHLC-C) was designed to investigate health-related control beliefs of persons with an existing medical condition. The aim of the present study was to examine the psychometric properties of this instrument in a culture characterized by external control beliefs and learned helplessness—contrary to the societal context of original test development. Altogether, 374 Hungarian patients with cancer, irritable bowel syndrome, diabetes, and cardiovascular and musculoskeletal disorders were enrolled in the study. Besides the MHLC-C, instruments measuring general control beliefs, anxiety, depression, self-efficacy, and health behaviors were also administered to evaluate the validity of the scale. Both exploratory and confirmatory factor analytic techniques were used to investigate the factor structure of the scale. Our results showed that the Hungarian adaptation of the instrument had a slightly different structure than the one originally hypothesized: in the present sample, a three-factor structure emerged where the items of the Doctors and the Others subscales loaded onto a single common component. Internal reliability of all three subscales was adequate (alphas between .71 and .79). Data concerning the instrument''s validity were comparable with previous results from Western countries. These findings may suggest that health locus of control can be construed very similarly to Western countries even in a post-communist society—regardless of the potential differences in general control beliefs.     

Longevity pathways converge on autophagy genes to regulate life span in Caenorhabditis elegans

Aging is a multifactorial process with many mechanisms contributing to the decline. Mutations decreasing insulin/IGF-1 (insulin-like growth factor-1) or TOR (target of rapamycin) kinase-mediated signaling, mitochondrial activity and food intake each extend life span in divergent animal phyla. Understanding how these genetically distinct mechanisms interact to control longevity is a fundamental and fascinating problem in biology. Here we show that mutational inactivation of autophagy genes, which are involved in the degradation of aberrant, damaged cytoplasmic constituents accumulating in all aging cells, accelerates the rate at which the tissues age in the nematode Caenorhabditis elegans. According to our results Drosophila flies deficient in autophagy are also short-lived. We further demonstrate that reduced activity of autophagy genes suppresses life span extension in mutant nematodes with inherent dietary restriction, aberrant insulin/IGF-1 or TOR signaling, and lowered mitochondrial respiration. These findings suggest that the autophagy gene cascade functions downstream of and is inhibited by different longevity pathways in C. elegans, therefore, their effects converge on autophagy genes to slow down aging and lengthen life span. Thus, autophagy may act as a central regulatory mechanism of animal aging.     

Chemical aspects of hydrogen sulfide measurements in physiological samples

Background

Owing to recent discoveries of many hydrogen sulfide-mediated physiological processes, sulfide biology is in the focus of scientific research. However, the promiscuous chemical properties of sulfide pose complications for biological studies, which led to accumulation of controversial observations in the literature.

Scope of review

We intend to provide an overview of fundamental thermodynamic and kinetic features of sulfide redox- and coordination-chemical reactions and protonation equilibria in relation to its biological functions. In light of these chemical properties we review the strengths and limitations of the most commonly used sulfide detection methods and recently developed fluorescent probes. We also give a personal perspective on blood and tissue sulfide measurements based on proposed biomolecule–sulfide interactions and point out important chemical aspects of handling sulfide reagent solutions.

Major conclusions

The diverse chemistries of sulfide detection methods resulted in orders of magnitude differences in measured physiological sulfide levels. Investigations that were aimed to dissect the underlying molecular reasons responsible for these controversies made the important recognition that there are large sulfide reserves in biological systems. These sulfide pools are tightly regulated in a dynamic manner and they are likely to play a major role in regulation of endogenous-sulfide-mediated biological functions and avoiding toxic side effects.

General significance

Working with sulfide is challenging, because it requires considerable amounts of chemical knowledge to adequately handle reagent sulfide solutions and interpret biological observations. Therefore, we propose that a rigorous chemical approach could aid the reconciliation of the increasing number of controversies in sulfide biology. This article is part of a Special Issue entitled Current methods to study reactive oxygen species - pros and cons and biophysics of membrane proteins. Guest Editor: Christine Winterbourn.     

Description of two new Ecuadorian Zilchistrophia Weyrauch, 1960, with the clarification of the systematic position of the genus based on anatomical data (Gastropoda,Stylommatophora, Scolodontidae)

Two new species of the genus Zilchistrophia Weyrauch, 1960 are described from Eastern Ecuadorian rain forest: Zilchistrophia hilaryae sp. n. and Zilchistrophia shiwiarorum sp. n. These two new species extend the distribution of the genus considerably northwards, because congeners have been reported from Peru only. For the first time we present anatomical data (radula, buccal mass, morphology of the foot and the genital structure) of Zilchistrophia species. According to these, the genus belongs to the family Scolodontidae, subfamily Scolodontinae (=“Systrophiini”). The previously assumed systematic relationship of Zilchistrophia with the Asian Corillidae and Plectopylidae based on the similarly looking palatal plicae is not supported.