The stress response to sensory contact in mice: genotype effect of the stimulus animal

Male wild house mice selectively bred for long and short attack latency (LAL and SAL, respectively) were previously shown to respond differently to chronic sensory contact stress with another SAL male. In the present study, it was investigated whether the genotype of the opponent played a role in the differential stress response of LAL and SAL mice. To this end, a LAL or SAL male was housed either under standard conditions (i.e. with a female), single, or in sensory contact with another LAL or SAL male for a period of 5 days. This period was chosen in order to study stress response adaptations. Although social isolation (singly housed) already induced changes in some physiological markers, in particular in LAL mice, the highest number of stress-induced changes was observed in LAL and SAL males living opposite a male of the other genotype. This was indicated in LAL mice by higher corticosterone levels, adrenal hypertrophy, and reduced seminal vesicle weight, and in SAL mice by higher ACTH levels and adrenal hypertrophy. Some mechanisms through which LAL and SAL mice could perceive each other as being different are proposed in the discussion, but it remains unclear why these mice show a differential stress response depending on the genotype of the opponent. In conclusion, it was demonstrated that a psychosocial stressor triggered line-specific changes in LAL and SAL mice, which were shown to be determined by the genotype of the stressor. These results open a new avenue to investigate mechanisms underlying genotypic-dependent stress responses.     

24-Hour motor activity after treatment with imipramine or fluvoxamine in major depressive disorder.

Psychomotor dysfunction in depression is related to alterations in the 24-h pattern of motor activity. After antidepressant treatment the diurnal pattern may be changed due to improvement of clinical state or pharmacological actions. The purpose of this study was to evaluate in 52 depressed in-patients the effects of imipramine (tricyclic antidepressant) and fluvoxamine (SSRI) on the 24-h motor activity. Motor activity was monitored by wrist-actigraphy during a medication-free period and after 4 weeks of treatment. Clinical improvement was not different after imipramine or fluvoxamine treatment. The Hamilton depression score decreased in patients treated with imipramine, as well as in patients treated with fluvoxamine. The clinical retardation score was also reduced in both treatment groups. However, patients treated with imipramine showed higher motor activity levels during the wake period in comparison to the medication-free period, and more fragmentation of motor activity during sleep. Treatment with fluvoxamine did not result in alterations in the 24-h pattern of motor activity. The improvement of depressive mood and retardation seems to play a minor role in the change of the pattern of motor activity after imipramine.     

Validation of the PHQ-15 for Somatoform Disorder in the Occupational Health Care Setting

Introduction Within the occupational health setting, somatoform disorders are a frequent cause of sick leave. Few validated screening questionnaires for these disorders are available. The aim of this study is to validate the PHQ-15 in this setting. Methods In a cross-sectional study of 236 sicklisted employees, we studied the performance of the PHQ-15 in comparison with the Mini International Neuropsychiatric Interview (MINI) as golden reference standard. We approached employees who were sick listed for a period longer than 6 weeks and shorter than 2 years for participation. This study was conducted on one location of a large occupation health service in the Netherlands, serving companies with more than 500 employees. All employees who returned the PHQ-15 were invited for the MINI interview. Specificity and sensitivity were calculated for optimal cut point and a receiver operating characteristic (ROC) was constructed. Results A total of 107 participants consented to participate in the MINI interview. A non-response analysis showed no significant differences between groups. According to the MINI, the prevalence of somatoform disorders was 21.5%, and the most frequent found disorder was a pain disorder. The PHQ-15 had an optimal cut point of 9 (patients scoring 9 or higher (≥9) were most likely to suffer from a somatoform disorder), with specificity and sensitivity equal to 61.9 and 56.5%, respectively. ROCs showed an area under the curve (AUC) of 0.63. Conclusion The PHQ-15 shows moderate sensitivity but limited efficiency with a cut point of 9 and can be a useful questionnaire in the occupational health setting.     

Decreased ciprofloxacin absorption with concomitant administration of ferrous fumarate

The effect of ferrous fumarate on the relative bioavailability of ciprofloxacin after a single 500 mg oral dose of ciprofloxacin was studied in eight healthy males. Blood samples were collected at regular intervals 0–24 h post-dose. Urine was collected during 24 h to determine the cumulative urine excretion of ciprofloxacin. Ciprofloxacin concentrations in serum and urine were determined by high pressure liquid chromatography. Mean area under the serum concentration—time curve decreased significantly (P<0.001) after ciprofloxacin was taken with 200 mg ferrous fumarate. The relative bioavailability was 30% when ciprofloxacin was given with ferrous fumarate. The maximum blood level decreased from 2.1±0.9 (control) to 0.6±0.2 mg/l (with ferrous fumarate). Further studies are needed to determine if chronic treatment with ferrous fumarate further decreases the relative bioavailability. For the moment administration of ciprofloxacin with ferrous fumarate should therefore be avoided.     

Advice on total-score reliability issues in psychosomatic measurement

Objective

This article addresses three reliability issues that are problematic in the construction of scales intended for use in psychosomatic research, illustrates how these problems may lead to errors, and suggests solutions.

Methods

We used psychometric results and present five computational studies. The first, third, and fourth studies are based on the generation of artificial data from psychometric models in combination with distributions for scale scores, as is common in psychometric research, whereas the second and fifth studies are analytical.

Results

The power of Student's t test depends more on sample size than on total-score reliability, but reliability must be high when one estimates correlations involving test scores. Short scales often do not allow total scores to be significantly different from a cutoff score. Coefficient alpha is uninformative about the factorial structure of questionnaires and is one of the weakest estimators of total-score reliability.

Conclusions

The relationship between questionnaire length/reliability and statistical power is complex. Both in research and individual diagnostics, we recommend the use of highly reliable scales so as to reduce the chance of faulty decisions. The conclusion calls for profound statistical research producing hands-on rules for researchers to act upon. Factor analysis should be used to assess the internal consistency of questionnaires. As a reliability estimator, alpha should be replaced by better and readily available methods.     

Effect of Newcastle disease virus infection on vitamin A metabolism in chickens

The effect of Newcastle disease virus (NDV, La Sota strain) infection on vitamin A metabolism was investigated in chickens maintained on normal or marginal vitamin A intake. NDV, a virus of the Paramyxoviridae family that primarily affects epithelial tissue, was administered at 4 wk of age. Plasma levels of retinol, retinol-binding protein and, to a lesser extent, transthyretin were found to be significantly lower during both the acute and postacute phases of infection in chickens fed a diet marginally deficient in vitamin A compared to noninfected birds fed the same diet, while vitamin A content in liver was unaffected. However, in chickens fed adequate vitamin A, NDV infection did not influence the parameters measured. Levels of retinol-binding protein in liver were significantly increased by inadequate vitamin A nutriture, but infection partly reduced this increase. The results suggest that the reduced vitamin A status in marginally vitamin A-deficient chickens infected with NDV can be attributed to a combination of a direct effect of the virus on retinol-binding protein metabolism in liver and an increased rate of utilization and catabolism of retinol and retinol-binding protein by extrahepatic tissues.     

Longitudinal measurement invariance of the Dutch Outcome Questionnaire-45 in a clinical sample

Purpose

In the absence of measurement invariance across measurement occasions, change scores based on pretest–posttest measurements may be inaccurate representations of real change on the latent variable. In this study, we examined whether measurement invariance held in the Dutch version of Outcome Questionnaire-45 (OQ-45).

Method

Using secondary data analysis of a sample of N?=?540 Dutch outpatients, we tested the stability of the factorial structure (gamma change) and the metric and scalar invariance (beta change) across pretest and posttest measurements using a combination of factor analysis and item response theory methodology.

Results

Results revealed a stable factorial structure from pretest to posttest and minor violations of metric invariance for two items in the Dutch OQ-45.

Conclusion

Even though for two items the assumption of invariance was violated, results suggest that the effects of these violations on practical change assessment using the OQ-45 were negligible.