Characterization of Cwc2, U6 snRNA, and Prp8 interactions destabilized by Prp16 ATPase at the transition between the first and second steps of splicing.

The spliceosome performs two consecutive transesterification reactions using one catalytic center, thus requiring its rearrangement between the two catalytic steps of splicing. The Prp16 ATPase facilitates exit from the first-step conformation of the catalytic center by destabilizing some interactions important for catalysis. To better understand rearrangements within the S. cerevisiae catalytic center, we characterize factors that modulate function of Prp16: Cwc2, N-terminal domain of Prp8, and U6-41AACAAU46 region. Alleles of these factors were identified through genetic screens for mutants that correct cs defects of prp16-302 allele. Several of the identified U6, cwc2, and prp8 alleles are located in close proximity of each other in cryo-EM structures of the spliceosomal catalytic conformations. Cwc2 and U6 interact with the intron sequences in the first step, but they do not seem to contribute to the stability of the second step catalytic center. On the other hand, the N-terminal segment of Prp8 not only affects intron positioning for the first step, but it also makes important contacts in the proximity of the active site for both the first and the second steps of splicing. By identifying interactions important for the stability of catalytic conformations, our genetic analyses indirectly inform us about features of the transition-state conformation of the spliceosome.

The influence of air humidity on human heat stress in a hot environment.

This article aims to present the physical adaptation capabilities of a human, seen as a response to extreme hot and dry or hot and humid conditions. Adaptation capabilities are expressed as safe exposure time in two variants: at rest and during physical activity. The study shows the results of calculations of the variability over time of the core temperature and skin temperature as well as heat balance. Calculations were made according to Standard No. EN ISO 7933:2005 on the basis of assumed and actual meteorological data. The results of the calculations show that in these conditions a hot but dry environment enables a human (although to a limited extent) to stay and perform low physical activity, provided access to drinking water is ensured. In contrast, a hot but humid environment causes more serious problems, due to the inability to reduce skin temperature by evaporation of sweat from the skin surface.

Effect of previous lowering of skin temperature on the time of safe exposure to a hot environment: a case study.

Objective. The purpose of the study was to determine the influence of initial conditions of a microclimate on volunteers' permissible exposure limits to a hot and humid environment. Materials and methods. Eighteen experimental studies with the participation of three volunteers were performed under controlled microclimate conditions (two climate chambers). The skin temperature and body core temperature were measured after they had stabilized in the following microclimate conditions: temperature of 17, 21 and 23 °C, relative humidity of 50% and hot microclimate conditions, i.e., temperature of 35 and 42 °C, humidity of 80% and physical work load at 30 W. The time needed to reach a body core temperature of 38 °C was determined under hot conditions. Heat accumulation was calculated. Results. Lowering volunteers' skin temperature under conditions of stabilized physiological parameters prolongs the time necessary for the body core temperature to reach 38 °C during physical work in a hot and humid environment. Conclusions. Appropriate acclimatization before exposure may prolong the time of safe work in a hot environment, e.g., during activities of rescue services.

Rearrangements within the U6 snRNA Core during the Transition between the Two Catalytic Steps of Splicing.

The RNA catalytic core of spliceosomes as visualized by cryoelectron microscopy (cryo-EM) remains unchanged at different stages of splicing. However, we demonstrate that mutations within the core of yeast U6 snRNA modulate conformational changes between the two catalytic steps. We propose that the intramolecular stem-loop (ISL) of U6 exists in two competing states, changing between a default, non-catalytic conformation and a transient, catalytic conformation. Whereas stable interactions in the catalytic triplex promote catalysis and their disruptions favor exit from the catalytic conformation, destabilization of the lower ISL stem promotes catalysis and its stabilization supports exit from the catalytic conformation. Thus, in addition to the catalytic triplex, U6-ISL acts as an important dynamic component of the catalytic center. The relative flexibility of the lower U6-ISL stem is conserved across eukaryotes. Similar features are found in U6atac and domain V of group II introns, arguing for the generality of the proposed mechanism.

Heart rate variability (HRV) and muscular system activity (EMG) in cases of crash threat during simulated driving of a passenger car.

OBJECTIVES: The aim of the study was to verify whether simultaneous responses from the muscular and circulatory system occur in the driver's body under simulated conditions of a crash threat. MATERIALS AND METHODS: The study was carried out in a passenger car driving simulator. The crash was included in the driving test scenario developed in an urban setting. In the group of 22 young male subjects, two physiological signals - ECG and EMG were continuously recorded. The length of the RR interval in the ECG signal was assessed. A HRV analysis was performed in the time and frequency domains for 1-minute record segments at rest (seated position), during undisturbed driving as well as during and several minutes after the crash. For the left and right side muscles: m. trapezius (TR) and m. flexor digitorum superficialis (FDS), the EMG signal amplitude was determined. The percentage of maximal voluntary contraction (MVC) was compared during driving and during the crash. RESULTS: As for the ECG signal, it was found that in most of the drivers changes occurred in the parameter values reflecting HRV in the time domain. Significant changes were noted in the mean length of RR intervals (mRR). As for the EMG signal, the changes in the amplitude concerned the signal recorded from the FDS muscle. The changes in ECG and EMG were simultaneous in half of the cases. CONCLUSION: Such parameters as mRR (ECG signal) and FDS-L amplitude (EMG signal) were the responses to accident risk. Under simulated conditions, responses from the circulatory and musculoskeletal systems are not always simultaneous. The results indicate that a more complete driver's response to a crash in road traffic is obtained based on parallel recording of two physiological signals (ECG and EMG).

Working life of women with disabilities--a review.

The aim of this study was to present the situation of women with disabilities on the labour market. Women with disabilities suffer from social and professional discrimination. They are discriminated because of their gender and disability. The Q1 Labour Force Participation Study (2013) showed that, in Poland, labour force participation for men and women with disabilities was 29.4% and 14.7%, respectively, while the unemployment rate was 16.1% for men and 17.2% for women. Quarterly information on employment, unemployment and economic inactivity was gathered from a Labour Force Survey in the first quarter of 2013; data from the Ministry of Labour and Social Policy were also included. The participants of the survey were 15 years old or older; they were members of a sample household. The methodology was based on definitions recommended by the International Labour Office and Eurostat. It is important that women with disabilities are substantially less professionally active, while the unemployment rate for them is only slightly higher.

[Determinants of quality of life people with physical disability]. / Uwarunkowania jakosci zycia osób niepelnosprawnych ruchowo.

BACKGROUND: 'Ihe aim of the study was to identify determinants of quality of life in people with physical disability. MATERIALS AND METHODS: A survey was conducted in a group of 426 people with physical disabilities (mean age, 44.4 years; SD = 12.6). The study group was divided into various sub-groups by the cause of dysfunction, degree of disability, time of disability diagnosis and issuing of disability certification, as well as age, gender and place of residence. Quality of life questionnaires SF36v2 served as a research tool. Assessing quality of life two major spheres of life associated with its quality, physical health and mental health, were taken into account. RESULTS: The results of logistic regression analysis showed that a lower quality of life is mainly influenced by demographic factors, such as low levels of education and living in small places of residence. CONCLUSION: The level of education and place of living can be considered as main factors predicting quality of life of people with physical disability.

Self-perceived quality of life of people with physical disabilities and labour force participation.

The aim of this study was to assess self-perceived quality of life of people with physical disabilities from the perspective of work. The following tools were used in the study: a personal questionnaire, an SF-36v2 questionnaire, an I-E Scale at Work and a Polish adaptation of the Ferrans and Powers Quality of Life Index. The study involved 426 disabled persons aged 18-65. It demonstrated that quality of life depends, to a large extent, on factors such as age and labour force participation. Duration of looking for work had a significant influence on the satisfaction from the psychological perspective and on the perception of general health. For the respondents who were unemployed and not looking for work, quality of life decreased with increased duration of professional inactivity.

Methods of estimating the effect of integral motorcycle helmets on physiological and psychological performance.

This article proposes a method for a comprehensive assessment of the effect of integral motorcycle helmets on physiological and cognitive responses of motorcyclists. To verify the reliability of commonly used tests, we conducted experiments with 5 motorcyclists. We recorded changes in physiological parameters (heart rate, local skin temperature, core temperature, air temperature, relative humidity in the space between the helmet and the surface of the head, and the concentration of O(2) and CO(2) under the helmet) and in psychological parameters (motorcyclists' reflexes, fatigue, perceptiveness and mood). We also studied changes in the motorcyclists' subjective sensation of thermal comfort. The results made it possible to identify reliable parameters for assessing the effect of integral helmets on performance, i.e., physiological factors (head skin temperature, internal temperature and concentration of O(2) and CO(2) under the helmet) and on psychomotor factors (reaction time, attention and vigilance, work performance, concentration and a subjective feeling of mood and fatigue).

CEF1/CDC5 alleles modulate transitions between catalytic conformations of the spliceosome.

Conformational change within the spliceosome is required between the first and second catalytic steps of pre-mRNA splicing. A prior genetic screen for suppressors of an intron mutant that stalls between the two steps yielded both prp8 and non-prp8 alleles that suppressed second-step splicing defects. We have now identified the strongest non-prp8 suppressors as alleles of the NTC (Prp19 complex) component, CEF1. These cef1 alleles generally suppress second-step defects caused by a variety of intron mutations, mutations in U6 snRNA, or deletion of the second-step protein factor Prp17, and they can activate alternative 3' splice sites. Genetic and functional interactions between cef1 and prp8 alleles suggest that they modulate the same event(s) in the first-to-second-step transition, most likely by stabilization of the second-step spliceosome; in contrast, alleles of U6 snRNA that also alter this transition modulate a distinct event, most likely by stabilization of the first-step spliceosome. These results implicate a myb-like domain of Cef1/CDC5 in interactions that modulate conformational states of the spliceosome and suggest that alteration of these events affects splice site use, resulting in alternative splicing-like patterns in yeast.

Heart rate variability and motion sickness during forklift simulator driving.

The goal of the study was to determine the effect of a 1-h hour long forklift truck virtual simulator driving on the mechanism of autonomic heart rate (HR) regulation in operators. The participants were divided into 2 subgroups: subjects with no definite inclination to motion sickness (group A) and subjects with a definite inclination to motion sickness (group B). Holter monitoring of electrocardiogram (ECG) signal was carried out in all subjects during the virtual simulator driving. For 12 consecutive epochs of ECG signal, HR variability analysis was conducted in time and frequency domains. In subjects with a definite inclination to motion sickness after ~30 min of the driving, changes in parameter values were found indicating an increase in sympathetic and parasympathetic activity with parasympathetic dominance.

Physical capacity of occupationally active population and capability to perform physical work.

The aim of this study was to determine what proportion of occupationally active Poles have working capacity that enables them to tolerate hard and very hard physical work. For this purpose physical capacity of 1188 occupationally active subjects (524 women and 664 men), aged 18-64 years was examined. Their maximal oxygen consumption (VO2max) was determined indirectly on the basis of their heart rate during an incremental exercise test on a bicycle ergometer. It was found that hard occupational physical work was an excessive load for almost 40% of men and women. This paper discusses how this load should be decreased with planned, appropriately long rest breaks. The percentage of persons for whom their hard physical work becomes an excessive load increases with age to such a degree that a new assessment of individual capability for such work is recommended for persons over 40 years old.

Job strain, overtime, life style, and cardiovascular risk in managers and physical workers.

The purpose of the study was to determine the relation between overtime, job strain and life style, and cardiovascular risk (CVR) in 97 managers and 98 physical workers. CVR was measured with the Framingham method. Information about job strain, overtime, life style and extra-occupational activities was obtained with a self-administered questionnaire. The results showed that both groups had a similar, medium-level job stress. Being a manager and having extra-occupational activities (self-education) were significantly related with CVR (p = .000, p = .035, respectively), whereas other factors that were analysed (i.e., physical work and overtime) were not. The managers were older than the physical workers; that may be why the factor of being a manager was significantly related to CVR. The extra-occupational activities connected with improving workers' skills may play an important role in the development of workers' overload and an increase in CVR.

Discontinuation of interferon beta therapy in multiple sclerosis patients with high pre-treatment disease activity leads to prompt return to previous disease activity.

BACKGROUND: A recommendation for the duration of interferon beta (IFNß) treatment in multiple sclerosis (MS) patients with a good response to this therapy has not been defined. Very limited data exist with regard to the effect of IFNß discontinuation on the subsequent course of MS. OBJECTIVE: To assess clinical activity in MS relapsing-remitting (MS RR) patients with high pre-treatment activity who discontinued IFNß treatment after approximately 2 years of treatment. METHODS: We determined the relapse rate and disability progression in 43 patients who discontinued IFNß after ~25 months of treatment. RESULTS: Within ~34 months post-treatment 28 patients (65%) experienced at least one severe relapse, and 8 MS patients experienced a relapse within 30 days post IFNß discontinuation. Disability progression measured by EDSS in the post-treatment period was 1.45±0.8 points per patient. CONCLUSION: These results indicate that IFNß did not induce a prolonged remission in MS patients and that disease activity returned to the previous rate within a short time after treatment cessation. Discontinuation of IFNß treatment in high activity pre-treatment MS patients with good response to this therapy is not recommended.

Injured professional drivers in Poland - an analysis of the causes and effects in relation to the time of the road accident.

INTRODUCTION: The objective of the paper was to present the results of an analysis of road accidents in professional drivers in Poland, from the point of view of their age, tenure, accident causes and effects in relation to the time of the accidents they were involved in. METHOD: Data were obtained from a database of the Central Statistical Office. Accidents recorded in statistical accident cards from 6 consecutive years were analysed. RESULTS: The overall number of injured professional drivers generally decreased over the 6 years, except for the last year of the period when the tendency to fatal and severe accidents between 23:00 and 6:59 increased. The highest percentage of fatal and severe accidents was found between 23:00 and 6:59 and was caused by medical emergencies and unsafe behaviour. The tenure of 70.89% of the injured drivers was under 10 years. Drivers who had worked for over 20 years had fewest injuries between 23:00 and 6:59. CONCLUSION: The results of the analysis may be used in changing work schedules to reduce the accident risk of the occupational groups at greatest risk.

Insights into branch nucleophile positioning and activation from an orthogonal pre-mRNA splicing system in yeast.

The duplex formed between the branch site (BS) of a spliceosomal intron and its cognate sequence in U2 snRNA is important for spliceosome assembly and the first catalytic step of splicing. We describe the development of an orthogonal BS-U2 system in S. cerevisiae in which spliceosomes containing a grossly substituted second-copy U2 snRNA mediate the in vivo splicing of a single reporter transcript carrying a cognate substitution. Systematic use of this approach to investigate requirements for branching catalysis reveals considerable flexibility in the sequence of the BS-U2 duplex and its positioning relative to the catalytic center. Branching efficiency depends on the identity of the branch nucleotide, its position within the BS-U2 duplex, and its distance from U2/U6 helix Ia. These results provide insights into substrate selection during spliceosomal branching catalysis; additionally, this system provides a foundation and tool for future mechanistic splicing research.

Coronary heart disease risk factors and cardiovascular risk in physical workers and managers.

This study aimed to assess the incidence of coronary heart disease (CHD) risk factors and cardiovascular risk in physical workers and managers in Poland. There were 232 male subjects: 123 managers (48.9 +/- 11.2 years old) and 109 physical workers (37.5 +/- 11.1 years old). The family history of CHD was recorded and anthropometric and biochemical indices, i.e., body mass index, visceral obesity index, blood pressure, glucose, total cholesterol, fibrinogen, HDL (high density lipoprotein), LDL (low density lipoprotein) and triglycerides were measured. Cardiovascular risk was assessed with the Systematic Coronary Risk Evaluation (SCORE) table system. The factors that turned out to be the most common in the managers were obesity, hypertension, and elevated levels of blood glucose and LDL, whereas cigarette smoking, premature CHD in the family and a high level of fibrinogen were more common in physical workers. Very high cardiovascular risk was found in 35% of managers and in 16% of physical workers.

Identification and characterization of a short 2'-3' bond-forming ribozyme.

A large number of natural and artificial ribozymes have been isolated since the demonstration of the catalytic potential of RNA, with the majority of these catalyzing phosphate hydrolysis or transesterification reactions. Here, we describe and characterize an extremely short ribozyme that catalyzes the positionally specific transesterification that produces a 2'-3' phosphodiester bond between itself and a branch substrate provided in trans, cleaving itself internally in the process. Although this ribozyme was originally derived from constructs based on snRNAs, its minimal catalytic motif contains essentially no snRNA sequence and the reaction it catalyzes is not directly related to either step of pre-mRNA splicing. Our data have implications for the intrinsic reactivity of the large amount of RNA sequence space known to be transcribed in nature and for the validity and utility of the use of protein-free systems to study pre-mRNA splicing.

A critical assessment of the utility of protein-free splicing systems.

U2 and U6 snRNAs form part of the catalytic spliceosome and represent strong candidates for components of its active site. Over the past decade it has become clear that these snRNAs are capable of catalyzing several different chemical reactions, leading to the widespread conclusion that the spliceosome is a ribozyme. Here, we discuss the advances in both protein-free and fully spliceosomal systems that would be required to conclude that the reactions observed to be catalyzed by protein-free snRNAs are related to splicing and question the reliability of snRNA-only systems as tools for mechanistic splicing research.