Prospective, observational, single-centre cohort study with an independent control group matched for age and sex aimed at investigating the significance of cholinergic activity in patients with schizophrenia: study protocol of the CLASH-study

INTRODUCTION

Alterations in the cholinergic metabolism may cause various clinical symptoms of schizophrenia. In addition to the 'monoamine hypothesis,' neuroinflammation is also discussed as a cause of schizophrenia. To date, there has been no evidence of alterations in the central cholinergic transmitter balance in patients with schizophrenia under clinical conditions. By contrast, studies in critically ill patients have established the measurement of acetylcholinesterase activity as a suitable surrogate parameter of central cholinergic transmitter balance/possible pathophysiological changes. Butyrylcholinesterase activity has been established as a parameter indicating possible (neuro)inflammatory processes. Both parameters can now be measured using a point-of-care approach. Therefore, the primary objective of this study is to investigate whether acetylcholinesterase and butyrylcholinesterase activity differs in patients with various forms of schizophrenia. Secondary objectives address the possible association between acetylcholinesterase and butyrylcholinesterase activity and (1) schizophrenic symptoms using the Positive and Negative Syndrome Scale, (2) the quantity of antipsychotics taken and (3) the duration of illness.

METHODS AND ANALYSIS

The study is designed as a prospective, observational cohort study with one independent control group. It is being carried out at the Department of Psychiatry and Psychotherapy III, Ulm University Hospital, Germany. Patient enrolment started in October 2020, and the anticipated end of the study is in January 2022. The enrolment period was set from October 2020 to December 2021 (extension required due to SARS-CoV-2 pandemic). The sample size is calculated at 50 patients in each group. Esterase activity is measured on hospital admission (acute symptomatology) and after referral to a postacute ward over a period of three consecutive days. The matched control group will be created after reaching 50 patients with schizophrenia. This will be followed by a comprehensive statistical analysis of the data set.

ETHICS AND DISSEMINATION

The study was registered prospectively in the German Clinical Trials Register (DRKS-ID: DRKS00023143,URL: https://www.drks.de/drks_web/navigate.do?navigationId=trial.HTML&TRIAL_ID=DRKS00023143) after approval by the ethics committee of the University of Ulm, Germany Trial Code No. 280/20.

TRIAL REGISTRATION NUMBER

DRKS00023143; Pre-results.

Slow skeletal muscles of the mouse have greater initial efficiency than fast muscles but the same net efficiency

The aim of this study was to determine whether the net efficiency of mammalian muscles depends on muscle fibre type. Experiments were performed in vitro (35 degrees C) using bundles of muscle fibres from the slow-twitch soleus and fast-twitch extensor digitorum longus (EDL) muscles of the mouse. The contraction protocol consisted of 10 brief contractions, with a cyclic length change in each contraction cycle. Work output and heat production were measured and enthalpy output (work + heat) was used as the index of energy expenditure. Initial efficiency was defined as the ratio of work output to enthalpy output during the first 1 s of activity. Net efficiency was defined as the ratio of the total work produced in all the contractions to the total, suprabasal enthalpy produced in response to the contraction series, i.e. net efficiency incorporates both initial and recovery metabolism. Initial efficiency was greater in soleus (30 +/- 1%; n=6) than EDL (23 +/- 1%; n=6) but there was no difference in net efficiency between the two muscles (12.6 +/- 0.7% for soleus and 11.7 +/- 0.5% for EDL). Therefore, more recovery heat was produced per unit of initial energy expenditure in soleus than EDL. The calculated efficiency of oxidative phosphorylation was lower in soleus than EDL. The difference in recovery metabolism between soleus and EDL is unlikely to be due to effects of changes in intracellular pH on the enthalpy change associated with PCr hydrolysis. It is suggested that the functionally important specialization of slow-twitch muscle is its low rate of energy use rather than high efficiency.

A longitudinal study of the development of low back pain in an industrial population

STUDY DESIGN

This is a longitudinal study in which industrial workers without chronic low back pain (LBP) were initially assessed with a comprehensive test battery and surveyed every 6 months thereafter for 2 years.

OBJECTIVE

To determine factors that may predispose industrial workers who lift over 5000 kg per shift to LBP.

SUMMARY OF BACKGROUND DATA

Prospective studies are small in number and often limited in breadth or depth of the test battery, methodologic issues, or investigator expertise. There are no prospective studies that focus on a homogeneous work sample of industrial employees.

METHODS

Production workers (n = 149) who volunteered for the 2-year study were assessed using physical measures (e.g., muscular strength, endurance, and flexibility), lifting kinematics (a sagittal plane box lift), and health, lifestyle, and work environment data (paper questionnaires). Follow-up questionnaires were distributed every 6 months for 2 years.

RESULTS

Using self-report of LBP as the main outcome measure, eight variables predicted LBP in this sample with a 75% correct prediction rate. Predictor variables included age, thoracic acceleration during the trunk velocity test, median frequency intercept of electromyography of the right L3 erector spinae, quadriceps strength, quadriceps endurance, self-assessment of fitness, having a confidante, and number of medications currently taken.

CONCLUSION

Results confirmed the multifactorial nature of low back pain and suggest that personal fitness is an important defense against low back pain, even in manual handling lifting tasks.

Reliability of MAOD measured at 110% and 120% of peak oxygen uptake for cycling

PURPOSE

The purpose of this study was to examine the test-retest reliability of maximal accumulated oxygen deficit (MAOD) measured at 110% and 120% of peak oxygen uptake (VO2) for cycling in seven untrained male and seven untrained female subjects.

METHODS

After one familiarization trial, all subjects performed two MAOD tests at a power output corresponding to 110% and two tests at 120% of VO2peak in random order. MAOD was calculated for each subject as the difference between O2 demand during exercise and the measured VO2.

RESULTS

The mean (+/-SEM) time to exhaustion for the group was not significantly different between trial 1 (226 +/- 13 s) and trial 2 (223 +/- 14 s) of the 110% test. Likewise, the difference in the time to exhaustion between trial 1 (158 +/- 11 s) and trial 2 (159 +/- 10 s) was not significant for the 120% test. The intraclass correlation coefficients for the time to exhaustion were 0.95 for the 110% test and 0.98 for the 120% test. The mean MAOD value obtained in trial 1 (2.62 +/- 0.17 L) was not significantly different from the mean value obtained in trial 2 (2.54 +/- 0.19 L) for the 110% test. Additionally, the mean values for the two trials did not differ significantly for MAOD (2.64 +/- 0.21 L for trial 1 and 2.63 +/- 0.19 L for trial 2) in the 120% test. The intraclass correlation coefficients for MAOD were 0.95 for the 110% test and 0.97 for the 120% test. All intraclass correlation coefficients were significant at P < 0.001.

CONCLUSIONS

When conducted under standardized conditions, the determination of MAOD for cycling was highly repeatable at both 110% and 120% of VO2peak in untrained male and female subjects.

Maximal accumulated oxygen deficit expressed relative to the active muscle mass for cycling in untrained male and female subjects

The purpose of the present study was to determine if gender differences exist in the maximal accumulated oxygen deficit (MAOD) or in the blood lactate (Lac-) and catecholamine responses to the MAOD test (120% peak oxygen uptake to exhaustion). The MAOD for cycling was measured in ten untrained male and ten untrained female subjects using the method described by Medbø et al. (Anaerobic capacity determined by maximal accumulated oxygen deficit. J Appl Physiol 64: 50-60, 1988). Blood Lac- and catecholamine concentrations were measured at rest, exhaustion and for 30 min following the MAOD test. Dual-energy X-ray absorptiometry was used to measure lean body mass (LBM) and to estimate the active muscle mass (AMM) for cycling. Males achieved a significantly higher MAOD than females following correction for AMM [126.3 (5.6) versus 108.3 (6.1) ml x kg AMM(-1), P = 0.04]. The peak blood lactate concentration ([Lac-]) in males [13.6 (0.9) mmol x l(-1)] was significantly higher than in females [10.0 (1.0) mmol x l(-1)]. Males obtained a 68% higher peak epinephrine concentration ([Epi]) than females, but the difference was not significant [1268 (188) pg x ml(-1) versus 755 (179) pg x ml(-1), P = 0.066]. However, plasma [Epi] was significantly higher for males than females at 1 min [824 (116) versus 489 (116) pg x ml(-1), P = 0.036] and 3 min [330 (52) versus 179 (42) pg x ml(-1), P = 0.039] into the recovery period. No gender-dependent differences in the norepinephrine concentration were observed at any time. Peak [Lac-] was significantly correlated with MAOD (ml x kg AMM(-1)) in females (r = 0.75), but not in males (r = 0.09). The peak plasma [Epi] was not significantly correlated with MAOD (ml x kg AMM(-1)) or peak [Lac-] in either group. These findings suggest that there are gender-dependent differences in MAOD even when expressed relative to the AMM for cycling. The higher blood [Lac-] in males compared to females obtained after supramaximal exercise was not caused by enhanced secretion of Epi. The greater MAOD in untrained males was not caused by a greater ability to produce Lac- or by enhanced secretion of Epi.

Effects of compensation strategy on job pay decisions

Previous research has revealed but not explained the occurrence of wide variations in pay for the same job, even within a single local labor market. We investigated how compensation managers from a wide variety of organizations combined information about current job pay rates, market rates, and job evaluation points to arrive at new pay rates. In addition, we examined the role of organizational pay leadership position and external or internal orientation in decisions about job pay, controlling for differences in organizational demographic characteristics. Results suggest that pay strategies affect assigned pay levels, with managers from market-leading and internally oriented firms assigning higher pay. In addition, pay strategies appear to influence the relative weights attached to market survey versus job evaluation information. Organizational demographics also affected assigned pay levels, but to a lesser extent than pay strategies.