Job crafting interventions: what works, for whom, why, and in which contexts? Research protocol for a systematic review with coincidence analysis

BACKGROUND

Recent challenges in the working world that resulted from the pandemic and technological advances have underlined the importance of flexibility in how jobs are designed. Job crafting (JC) refers to self-initiated changes that employees introduce to their jobs to optimize their job design and increase the fit between the job and their needs and preferences. These behaviors can be stimulated by job crafting training interventions, which aim to change how individual employees design, organize, or manage their work. However, since the interventions are implemented in various ways, we do not know which context and intervention factors are necessary or sufficient to achieve desired outcomes. Without this knowledge, benefitting from the potential of job crafting interventions is limited. The overall aim of this project will be to investigate what combinations of context, intervention, and mechanism factors are linked with effective JC interventions. Specifically, we will detect what factors are minimally sufficient and/or necessary to produce a successful JC intervention, how they combine, as well as what are the multiple alternative paths to their success.

METHODS

We will perform a systematic review of the JC interventions literature combined with coincidence analysis (CNA). We will search electronic databases of journals and utilize Rayyan software to make decisions regarding inclusion. Data regarding context (e.g., fit), intervention (e.g., types of activities), mechanisms (e.g., intention implementation), and outcomes (e.g., employee well-being, job performance) will be extracted using a pre-piloted form and coded into a crisp-set (factor present vs. absent). Analyses will be carried out using the CNA package in R.

DISCUSSION

This review will address gaps in knowledge about the context, intervention, and mechanism-related factors that may impact the effects of JC interventions. Consequently, this review will help develop a program theory for JC interventions that explains what works, how and under which circumstances. Applying CNA to synthesize these complex solutions across multiple studies provides an innovative method that may be used in future review attempts evaluating the implementation of interventions. Finally, our synthesis will provide knowledge relevant to organizational practitioners and scholars who want to implement JC interventions.

TRIAL REGISTRATION

https://osf.io/2g6yx.

A Data-Driven Clustering Method for Discovering Profiles in the Dynamics of Major Depressive Disorder Using a Smartphone-Based Ecological Momentary Assessment of Mood

BACKGROUND

Although major depressive disorder (MDD) is characterized by a pervasive negative mood, research indicates that the mood of depressed patients is rarely entirely stagnant. It is often dynamic, distinguished by highs and lows, and it is highly responsive to external and internal regulatory processes. Mood dynamics can be defined as a combination of mood variability (the magnitude of the mood changes) and emotional inertia (the speed of mood shifts). The purpose of this study is to explore various distinctive profiles in real-time monitored mood dynamics among MDD patients in routine mental healthcare.

METHODS

Ecological momentary assessment (EMA) data were collected as part of the cross-European E-COMPARED trial, in which approximately half of the patients were randomly assigned to receive the blended Cognitive Behavioral Therapy (bCBT). In this study a subsample of the bCBT group was included (n = 287). As part of bCBT, patients were prompted to rate their current mood (on a 1-10 scale) using a smartphone-based EMA application. During the first week of treatment, the patients were prompted to rate their mood on three separate occasions during the day. Latent profile analyses were subsequently applied to identify distinct profiles based on average mood, mood variability, and emotional inertia across the monitoring period.

RESULTS

Overall, four profiles were identified, which we labeled as: (1) "very negative and least variable mood" (n = 14) (2) "negative and moderate variable mood" (n = 204), (3) "positive and moderate variable mood" (n = 41), and (4) "negative and highest variable mood" (n = 28). The degree of emotional inertia was virtually identical across the profiles.

CONCLUSIONS

The real-time monitoring conducted in the present study provides some preliminary indications of different patterns of both average mood and mood variability among MDD patients in treatment in mental health settings. Such varying patterns were not found for emotional inertia.

Internet-based self-help intervention aimed at increasing social self-efficacy among internal migrants in Poland: Study protocol for a randomized controlled trial

BACKGROUND

Migration is a challenging life transition that may be a source of various problems related to well-being and mental health. However, the psychological adaptation of migrants may be potentially facilitated by social self-efficacy-the beliefs in one's ability to initiate and maintain interpersonal relationships. Previous research suggests that social self-efficacy is positively related to adjustment and negatively related to loneliness, depression, and psychological distress. Research also confirms that self-efficacy beliefs can be effectively enhanced using Internet-based interventions. These results served as a background for creating the New in Town, a self-help Internet-based intervention for internal migrants in Poland that aims at increasing social self-efficacy. Exercises in the intervention are based on the principles of Cognitive Behavioral Therapy and relate to sources of self-efficacy beliefs: mastery experiences, vicarious experiences, verbal persuasions, and emotional and physiological states. Users complete increasingly challenging tasks that encourage them to interact with their environment. The aim of this trial was to investigate the efficacy of the New in Town intervention.

METHODS

The efficacy of the New in Town intervention will be tested in a two-arm randomized controlled trial with a waitlist control group. Social self-efficacy will be the primary outcome. Secondary outcomes will include loneliness, perceived social support, and satisfaction with life. Additionally, we will measure user experience among participants allocated to the experimental group. We aim to recruit a total of N = 280 participants aged at least 18 years who have changed their place of residence in the last 6 months and have an Internet connection. Participants will be assessed at baseline, 3-week post-test, and 8-week follow-up.

DISCUSSION

The trial will provide insights into the efficacy of Internet-based self-help interventions in increasing social self-efficacy. Given that the intervention works, New in Town could provide an easily accessible support option for internal migrants in Poland.

TRIAL REGISTRATION

The trial was registered with ClinicalTrials.gov (identifier: NCT04088487) on 11th September 2019.

1228 New predictors of sudden cardiac death in hypertrophic cardiomyopathy

BACKGROUND

Hypertrophic cardiomyopathy (HCM) is a heart disease characterized by hypertrophy of the left ventricular myocardium. HCM is the most common cause of sudden cardiac death (SCD) in young people and competitive athletes due to fatal ventricular arrhythmias. However, in most patients, HCM has a benign course. That is why it is of utmost importance to properly evaluate patients and identify those who would benefit from a cardioverter-defibrillator (ICD) implantation. The HCM SCD-Risk Calculator is a useful tool for estimating the risk of SCD. The parameters included in the model at evaluation are: age, maximum left ventricular (LV) wall thickness, left atrial (LA) dimension, maximum gradient in left ventricular outflow tract, family history of SCD, non-sustained ventricular tachycardia (nsVT) and unexplained syncope. Nevertheless, there is potential to improve and optimize the effectiveness of this tool in clinical practice. Therefore, the following new risk factors are proposed: LV global longitudinal strain (GLS), LV average strain (ASI) and LA volume index (LAVI). GLS and ASI are sensitive and noninvasive methods of assessing LV function. LAVI more accurately characterizes the size of the left atrium in comparison to the LA dimension.

METHODS

252 HCM patients (aged 20-88 years, of which 49,6% were men) treated in our Department from 2005 to 2018, were examined. The follow-up period was 0-13 years (average: 3.8 years). SCD was defined as sudden cardiac arrest (SCA) or an appropriate ICD intervention. All patients underwent an echocardiographic examination. The medical and family histories were collected and ICD examinations were performed.

RESULTS

76 patients underwent an ICD implantation during the follow-up period. 20 patients have reached an SCD end-point. 1 patient died due to SCA and 19 had an appropriate ICD intervention.

There were statistically significant differences of GLS and ASI values between SCD and non-SCD groups; p = 0.026389 and p = 0.006208, respectively. The average GLS in the SCD group was -12.4% ± 3.4%, and -15.1% ± 3.5% in the non-SCD group. The average ASI values were -9.9% ± 3.8% and -12.4% ± 3.5%, respectively. There was a statistically significant difference between LAVI values in SCD and non-SCD groups; p = 0.005343. The median LAVI value in the SCD group was 45.7 ml/m2 and 37.6 ml/m2 in the non-SCD group. The ROC curves showed the following cut-off points for GLS, ASI and LAVI: -13.8%, -13.7% and 41 ml/m2, respectively.

Cox’s proportional hazards model for the parameters used in the Calculator was at the borderline of significance; p = 0.04385. The model with new variables (GLS and LAVI instead of LA dimension) was significant; p = 0.00094. The important factors were LAVI; p = 0.000075 and nsVT; p = 0.012267.

CONCLUSIONS

The proposed new SCD risk factors were statistically significant in the study population and should be taken into account when considering ICD implantation.

P1291 Are we ready for machine learning in HCM risk stratification?

BACKGROUND

Hypertrophic cardiomyopathy (HCM) is a heart disease characterized by hypertrophy of the left ventricular myocardium. The disease is the most common cause of sudden cardiac death (SCD) in young people and competitive athletes due to fatal ventricular arrhythmias, but in most patients, however, HCM has a benign course. Therefore, it is of the utmost importance to properly evaluate patients and identify those who would benefit from a cardioverter-defibrillator (ICD) implantation. The HCM SCD-Risk Calculator is a useful tool for estimating the 5-year risk of SCD. Parameters included in the model at evaluation are: age, maximum left ventricular wall thickness, left atrial dimension, maximum gradient in left ventricular outflow tract, family history of SCD, non-sustained ventricular tachycardia and unexplained syncope. Patients’ risk of SCD is classified as low (<4%), intermediate (4-<6%) or high (≥6%). Those in the high-risk group should have an ICD implantation. It can also be considered in the intermediate-risk group. However, the calculator still needs improvement and machine learning (ML) has the potential to fulfill this task. ML algorithm creates a model for solving a specific problem without explicit programming - instead it relies only on available data - by discovering patterns and relations.

METHODS

252 HCM patients (aged 20-88 years, 49,6% were men) treated in our Department from 2005 to 2018, have been enrolled. The follow-up lasted 0-13 years (average: 3.8 years). SCD was defined as sudden cardiac arrest (SCA) or an appropriate ICD intervention. All parameters from HCM SCD-Risk Calculator have been obtained and the risk of SCD has been calculated for all patients during the first echocardiographic evaluation. ML model with variables from HCM SCD-Risk Calculator has been created. Both methods have been compared.

RESULTS

20 patients reached an SCD end-point. 1 patient died due to SCA and 19 had an appropriate ICD intervention. Among them, there were respectively 6, 7 and 7 patients in the low, intermediate and high-risk group of SCD. 1 patient, who died, had a low risk. The ML model correctly assessed the SCD event only in 1 patient. According to ML, the risk of SCD ≤2.07% was a negative predictor.

CONCLUSIONS

The study did not show an advantage of ML over HCM SCD-Risk Calculator. Because of the characteristic of the dataset (approximately the same number of features and observations), the selection of machine learning algorithms was limited. Best results (evaluated using LOOCV) were achieved with a decision tree. We expect that bigger dataset would allow improving model performance because of strong regularization need in the current setup.

P1395 New predictors of burned-out phase in hypertrophic cardiomyopathy

BACKGROUND

Hypertrophic cardiomyopathy (HCM) is a heart disease characterized by hypertrophy of the left ventricular myocardium. The structural and functional abnormalities cannot be explained by flow-limiting coronary artery disease or loading conditions. HCM has a benign course, however approximately 5% of these patients suffer from the end-stage of the disease. The so-called burned-out phase, characterized by systolic dysfunction with a left ventricular ejection fraction ≤50%, is often associated with wall thinning and chamber dilation. These patients should have more frequent clinic visits and have a more intensive treatment plan. They are also candidates for heart transplantation. Currently there are no risk factors of progression to burned-out phase before the onset of heart failure symptoms. Therefore, the potential risk factors: left ventricular global longitudinal strain (GLS), left ventricular average strain (ASI), right ventricular average strain (RV-ASI) and left atrial volume index (LAVI), have been examined. GLS, derived from speckle tracking echocardiography, and ASI, derived from tissue doppler imaging, are the sensitive and noninvasive methods of assessing the ventricular function. LAVI more accurately characterizes the size of the left atrium, which usually increases in the course of the disease.

METHODS

A total of 252 patients with HCM (aged 20-88 years, 49,6% were men), treated in our Department have been enrolled in the study. GLS, ASI, RV-ASI and LAVI assessment has been made in addition to standard echocardiographic examination. Burned-out was characterized as systolic dysfunction with a left ventricular ejection fraction ≤50%.

RESULTS

5.6% patients in the study population were diagnosed with burned-out phase in hypertrophic cardiomyopathy.

The t-Student test and t-Student test with Cochran-Cox adjustment showed statistically significant differences of GLS and ASI values between burned-out and non-burned-out groups; p = 0.000001 and p < 0.000001, respectively. Average and median values of GLS in burned-out group were -7.4% ± 2.9%, -7.1% and -15.3% ± 4.3%, -15.4% in non-burned-out group. For ASI those values were respectively -7.6% ± 2.2%, -7.1% and -12.9% ± 4.5%, -13.0%.

The Mann-Whitney test showed statistically significant differences of RV-ASI and LAVI values between burned-out and non-burned-out groups; p = 0.000208 and p = 0.005302, respectively. Median value of RV-ASI in burned-out group was -15.8% and -27.1% in non- burned-out group. Median value of LAVI in burned-out group was 52.6 ml/m2 and 37.8 ml/m2 in non-burned-out group.

CONCLUSIONS

Each of the proposed new risk factors of burned-out development was statistically significant in the study population. Therefore, all HCM patients should have regular echocardiographic examinations and those with deteriorating values of new parameters should become the subjects of intensified medical care.

Positive Emotions at Work and Job Crafting: Results From Two Prospective Studies

To date, research confirmed the effects of job crafting on the functioning of employees and organizations. In contrast, the evidence for the predictors of job crafting is limited. Based on broaden-and-build (B&B) theory, it may be assumed that high positive emotions at work would predict high job crafting behaviors at follow-ups. In line with social cognitive theory (SCT), it may be hypothesized that self-efficacy would mediate the relationship between positive emotions at work and following job crafting behaviors. The hypotheses were tested in a three-wave prospective study (Study 1, N = 124), with individual beliefs measured as the predictors. In a three-wave prospective Study 2 (N = 99), individual perceptions of collective flow at work and collective efficacy were assessed. Results of Studies 1 and 2 indicated that positive emotions at work predicted increasing structural resources, a job crafting dimension. Moreover, findings of Study 2 showed that collective flow at work predicted another job crafting dimension, i.e., increasing social resources. These results may inform good practices and help in designing individual- and team-level interventions enhancing job crafting behaviors.

[A job crafting measure: psychometric properties of the Polish version of the Job Crafting Scale]

BACKGROUND

The interest among researchers and practitioners in job crafting has been growing for the last dozen of years. Job crafting refers to behaviors that employees engage in to align aspects of their jobs with their own skills and needs. The aim of this paper was to analyze psychometric properties of the Polish version of a job crafting measure - the <i>Job Crafting Scale</i> (JCS).

MATERIAL AND METHODS

The original JCS consists of 21 items and has 4 subscales: <i>Increasing Structural Job Resources</i>, <i>Increasing Social Job Resources</i>,<i> Increasing Challenging Job Demands</i>, and <i>Decreasing Hindering Job Demands</i>. Confirmatory factor analysis, internal consistency analysis, theoretical validity analysis and test-retest stability analysis were carried out among 249 white collar workers who use information and communication technology (ICT) in their daily work. Multigroup confirmatory factor analysis and invariance test were carried out among 228 white collar workers using ICT and additionally working in a team for most of the week.

RESULTS

The Polish version of the JCS displays satisfactory internal consistency, theoretical validity, and test-retest stability. The results of the confirmatory factor analysis showed a 4-dimensional structure of the JCS. Four items were excluded from the Polish version of the JCS because of low factor loadings. The results of invariance test showed that factor loadings were invariant across groups.

CONCLUSIONS

The Polish version of the JCS consists of 17 items and - like the original scale - has 4 subscales. Additional studies are recommended to confirm the internal structure of the JCS and measurement invariance across different occupational groups. Med Pr. 2019;70(4):445-57.

European COMPARative Effectiveness research on blended Depression treatment versus treatment-as-usual (E-COMPARED): study protocol for a randomized controlled, non-inferiority trial in eight European countries

Background

Effective, accessible, and affordable depression treatment is of high importance considering the large personal and economic burden of depression. Internet-based treatment is considered a promising clinical and cost-effective alternative to current routine depression treatment strategies such as face-to-face psychotherapy. However, it is not clear whether research findings translate to routine clinical practice such as primary or specialized mental health care. The E-COMPARED project aims to gain knowledge on the clinical and cost-effectiveness of blended depression treatment compared to treatment-as-usual in routine care.

Methods/design

E-COMPARED will employ a pragmatic, multinational, randomized controlled, non-inferiority trial in eight European countries. Adults diagnosed with major depressive disorder (MDD) will be recruited in primary care (Germany, Poland, Spain, Sweden, and the United Kingdom) or specialized mental health care (France, The Netherlands, and Switzerland). Regular care for depression is compared to “blended” service delivery combining mobile and Internet technologies with face-to-face treatment in one treatment protocol. Participants will be followed up at 3, 6, and 12 months after baseline to determine clinical improvements in symptoms of depression (primary outcome: Patient Health Questionnaire-9), remission of depression, and cost-effectiveness. Main analyses will be conducted on the pooled data from the eight countries (n = 1200 in total, 150 participants in each country).

Discussion

The E-COMPARED project will provide mental health care stakeholders with evidence-based information and recommendations on the clinical and cost-effectiveness of blended depression treatment.

Trial registration

France: ClinicalTrials.gov NCT02542891. Registered on 4 September 2015; Germany: German Clinical Trials Register DRKS00006866. Registered on 2 December 2014; The Netherlands: Netherlands Trials Register NTR4962. Registered on 5 January 2015; Poland: ClinicalTrials.Gov NCT02389660. Registered on 18 February 2015; Spain: ClinicalTrials.gov NCT02361684. Registered on 8 January 2015; Sweden: ClinicalTrials.gov NCT02449447. Registered on 30 March 2015; Switzerland: ClinicalTrials.gov NCT02410616. Registered on 2 April 2015; United Kingdom: ISRCTN registry, ISRCTN12388725. Registered on 20 March 2015.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-016-1511-1) contains supplementary material, which is available to authorized users.

Effects of Internet-Based Self-Efficacy Intervention on Secondary Traumatic Stress and Secondary Posttraumatic Growth among Health and Human Services Professionals Exposed to Indirect Trauma

Background: Although the evidence for the associations among self-efficacy, secondary traumatic stress (STS) and secondary posttraumatic growth (SPTG) is mounting, there is a lack of the experimental evidence for the influence of self-efficacy on positive and negative mental health outcomes among professionals indirectly exposed to trauma.

Purpose: This study investigated the effects of an internet-based self-efficacy intervention (the experimental condition), compared to an education (the active control condition) on STS and SPTG among workers exposed to traumatic events indirectly, through their clients. We hypothesized that the group assignment (experimental vs. control) would affect STS and SPTG indirectly, with a mediating role of self-efficacy beliefs.

Methods: Participants were 168 health and human services professionals (78% women), exposed indirectly to a traumatic event at work. They were randomly assigned to either a 4-session internet-based self-efficacy intervention (n = 87) or an education control group (n = 81) which received information about coping resources and consequences of stressors at work or at home. STS, SPTG, and self-efficacy were measured at the baseline (Time 1), 1-month follow-up (Time 2) and 2-month follow-up (Time 3).

Results: Analysis of covariance showed that the group assignment had a significant effect on STS (Time 2) and self-efficacy (Time 2), with lower STS and higher self-efficacy reported by the self-efficacy intervention participants. Compared to the experimental group, the active control (education) group participants reported higher SPTG at Time 2. Mediation analyses indicated that the group assignment had indirect effects on STS and SPTG at Time 3. Workers who experienced increases in self-efficacy (Time 2) through the intervention were more likely to report lower STS and higher SPTG at Time 3.

Conclusion: Elucidating the mediating processes that explain why an intervention for secondary trauma works is essential in order to develop more effective support systems that promote improved mental health outcomes among health and human services professionals. Prevention programs for workers exposed indirectly to traumatic events may target self-efficacy enhancement and education.

From Exhaustion to Disengagement via Self-Efficacy Change: Findings from Two Longitudinal Studies among Human Services Workers

This longitudinal research examined the relationship direction between burnout components (exhaustion and disengagement) within the context of personal resources measured by self-efficacy and social support. In line with the conservation of resources theory we hypothesized that exhaustion may trigger a spiral loss of personal resources where self-efficacy declines and subsequently, social support also declines and in turn predict disengagement. Participants in Study 1 were mental healthcare providers (N = 135) working with U.S. military personnel suffering from trauma. Participants in Study 2 were healthcare providers, social workers, and other human services professionals (N = 193) providing various types of services for civilian trauma survivors in Poland. Baseline and 6-month follow-up measurements included burnout components, burnout self-efficacy and perceived social support. The path analysis showed consistent results for both longitudinal studies; exhaustion measured at Time 1 led to disengagement at Time 2, after controlling for baseline disengagement levels. Across Study 1 and Study 2 these associations were mediated by self-efficacy change: Higher exhaustion led to greater decline in self-efficacy which in turn explained higher disengagement at the follow-up. Social support, however, did not mediate between self-efficacy and disengagement. These mediating effects were invariant across Studies 1 and 2, although the mean levels of burnout and personal resources differed significantly. The results contribute to a discussion on the internal structure of job burnout and a broader understanding of the associations between exhaustion and disengagement that may be explained by the underlying mechanism of change in self-efficacy.

Associations between job burnout and self-efficacy: a meta-analysis

BACKGROUND AND OBJECTIVES

This study aimed at systematically reviewing and meta-analyzing the strength of associations between self-efficacy and job burnout (the global index and its components). We investigated whether these associations would be moderated by: (a) the type of measurement of burnout and self-efficacy, (b) the type of occupation, (c) the number of years of work experience and age, and (d) culture.

DESIGN AND METHODS

We systematically reviewed and analyzed 57 original studies (N = 22,773) conducted among teachers (k = 29), health-care providers (k = 17), and other professionals (k = 11).

RESULTS

The average effect size estimate for the association between self-efficacy and burnout was of medium size (-.33). Regarding the three burnout components, the largest estimate of the average effect (-.49) was found for the lack of accomplishment. The estimates of the average effect were similar, regardless of the type of measures of burnout and self-efficacy measurement (general vs. context-specific). Significantly larger estimates of the average effects were found among teachers (compared to health-care providers), older workers, and those with longer work experience.

CONCLUSIONS

Significant self-efficacy-burnout relationships were observed across countries, although the strength of associations varied across burnout components, participants' profession, and their age.

Association of single-nucleotide polymorphisms of the tau gene with late-onset Parkinson disease

CONTEXT

The human tau gene, which promotes assembly of neuronal microtubules, has been associated with several rare neurologic diseases that clinically include parkinsonian features. We recently observed linkage in idiopathic Parkinson disease (PD) to a region on chromosome 17q21 that contains the tau gene. These factors make tau a good candidate for investigation as a susceptibility gene for idiopathic PD, the most common form of the disease.

OBJECTIVE

To investigate whether the tau gene is involved in idiopathic PD.

DESIGN, SETTING, AND PARTICIPANTS

Among a sample of 1056 individuals from 235 families selected from 13 clinical centers in the United States and Australia and from a family ascertainment core center, we tested 5 single-nucleotide polymorphisms (SNPs) within the tau gene for association with PD, using family-based tests of association. Both affected (n = 426) and unaffected (n = 579) family members were included; 51 individuals had unclear PD status. Analyses were conducted to test individual SNPs and SNP haplotypes within the tau gene.

MAIN OUTCOME MEASURE

Family-based tests of association, calculated using asymptotic distributions.

RESULTS

Analysis of association between the SNPs and PD yielded significant evidence of association for 3 of the 5 SNPs tested: SNP 3, P =.03; SNP 9i, P =.04; and SNP 11, P =.04. The 2 other SNPs did not show evidence of significant association (SNP 9ii, P =.11, and SNP 9iii, P =.87). Strong evidence of association was found with haplotype analysis, with a positive association with one haplotype (P =.009) and a negative association with another haplotype (P =.007). Substantial linkage disequilibrium (P<.001) was detected between 4 of the 5 SNPs (SNPs 3, 9i, 9ii, and 11).

CONCLUSIONS

This integrated approach of genetic linkage and positional association analyses implicates tau as a susceptibility gene for idiopathic PD.

Identification of a new autosomal dominant limb-girdle muscular dystrophy locus on chromosome 7

We report the identification of a new locus for autosomal dominant limb-girdle muscular dystrophy (LGMD1) on 7q. Two of five families (1047 and 1701) demonstrate evidence in favor of linkage to this region. The maximum two-point LOD score for family 1047 was 3.76 for D7S427, and that for family 1701 was 2.63 for D7S3058. Flanking markers place the LGMD1 locus between D7S2423 and D7S427, with multipoint analysis slightly favoring the 9-cM interval spanned by D7S2546 and D7S2423. Three of five families appear to be unlinked to this new locus on chromosome 7, thus establishing further heterogeneity within the LGMD1 diagnostic classification.

The content of free amino acids in plasma of hens of different strains

Free amino acids were estimated in the plasma of Leghorn, Cornish and White Rock hens, bred under identical conditions. It was found that the plasma of Leghorn hens had a lower content of amino acids. The differences were especially pronounced for proline, glutamic acid and glycine. It was established that a lower percentage of valine, leucine and isoleucine was typical of Leghorn hens in comparison with Cornish hens. The obtained results indicate that the level of free amino acids in blood plasma is genetically controlled.

Effect of starvation on the content of free amino acids in plasma of different breeds of hen

'Leghorn', 'Cornish' and 'White Rock' hens were subjected to starvation. Free amino acids were determined in blood samples taken after 48, 72 and 96 h of starvation. A progressive decrease in concentration of the majority of amino acids was found. Changes in amino acid concentrations during starvation were dependent on the breed of hen.

The level of free amino acids in erythrocytes of different breeds of hen

The content of free amino acids was determined in erythrocytes of adult 'Leghorn' (Lg, 'White Rock' (WR) and 'Cornish' (Cr) hens, bred under identical conditions. The concentration of total amino acids was twice as high in the erythrocytes as in plasma, amounting to 396 μm/100 ml, 424 μm/100 ml and 475μm/100 ml in 'White Rock', 'Cornish' and 'Leghorn' hens, respectively.Significant differences were found in the ratio of basic amino acids to acidic amino acids. These values were 0.76, 1.75 and 3.19 in 'White Rick', 'Leghorn' and 'Cornish' hens, respectively; in the plasma of all 3 breeds the ratio was 1. Statistically significant interbreed differences were expressed more distinctly in erythrocyte than in plasma amino acid concentrations. For absolute concentrations the differences were significant in the case of 9 amino acids.