Single nucleotide polymorphism analysis of corticotropin-releasing factor-binding protein gene in recurrent major depressive disorder.

Corticotropin-releasing factor-binding protein (CRF-BP) regulates the availability of free CRF and is a functional candidate gene for affective disorders. Previous research showed an association between polymorphisms in the CRF-BP gene and recurrent major depression (MDD) in a Swedish sample. The purpose of the current study was to re-evaluate the previous findings in an extended Swedish sample and in an independent Belgian sample of patients with recurrent MDD and in control samples. In total, 317 patients and 696 control individuals were included. Five single nucleotide polymorphisms (SNPs) and a deletion polymorphism in the CRF-BP gene were genotyped and the haplotype block structure of the gene was assessed. In the extended Swedish population, there was a trend towards an association between two SNPs and MDD. The subsequent gender analysis showed significant associations of three SNPs (CRF-BPs2 T; CRF-BPs11 T and CRF-BPs12 C) and haplotype G_T_C_T_C with MDD in Swedish males. However, these findings did not withstand correction for multiple testing and there were no significant SNP or haplotype associations in the Belgian MDD sample. In conclusion, this study does not provide confirmatory evidence for a role of the CRF-BP gene in the vulnerability for MDD in general. The association between genetic CRF-BP variants and MDD may be sexually dimorphic, but this issue requires further investigation in a larger sample.

A biopsychosocial model as a guide for psychoeducation and treatment of depression.

Effective treatment of severe or chronic unipolar depression requires the combination of pharmacological and psychotherapeutic interventions, and demands a theoretical paradigm integrating biological and psychosocial aspects of depression. Supported by recent research, we propose in our article a biopsychosocial diathesis-stress model of depression. Its basic aim is psychoeducational: to provide therapists, patients, and their environment a constructive conceptual framework to understand depressive complaints, vulnerability, and stress. The core of the model consists of the concept of psychobiological vulnerability, which is determined by risk factors-of a biogenetic, psychological, somatic, and societal nature-and by protective factors. Life events with an idiosyncratic, stress-inducing value interact with this vulnerability, triggering severe or chronic distress that affects the individual's resilience and leads to symptoms of depression. The pathogenesis of depression is symbolized by a negative downward loop, in which interactions among symptoms, vulnerability, and stressors drive the patient toward a depressive condition. Moreover, experiencing recurrent depression influences psychobiological vulnerability, the occurrence of stressors, and tremendously increases the risk of further relapse. The model stresses the self-evident integration of biological and psychological therapeutic interventions that need to focus on symptom reduction and on relapse prevention. Moreover, it offers the patient and therapist a psychoeducational context in which the individual's vulnerability and depressive symptoms can be treated. Finally, applications of the depression model as a therapeutic approach to severe depression in the phases of remoralization, symptom reduction, and relapse prevention are presented.

Combined dexamethasone/CRF test in remitted outpatients with recurrent major depressive disorder.

BACKGROUND: Hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis is a prominent neurobiological finding during a major depressive episode, reflecting a state dependent factor. An issue under investigation is whether the dysfunction of the HPA axis has also a role to play as a state-independent or trait factor for major depressive disorder (MDD). In relation to this, it is important to examine HPA axis function in patients who are clinically remitted from depression. METHODS: Twenty-three remitted outpatients with recurrent MDD and 23 age- and gender-matched control individuals without a history of MDD participated in the sensitive combined dexamethasone/corticotropin-releasing factor (DEX/CRF) test. RESULTS: Free salivary cortisol responses were not significantly different between the two groups, although three patients (13%) displayed extremely elevated cortisol responses after CRF. LIMITATIONS: Limited sample size. All but one patient were under treatment with an antidepressant. CONCLUSIONS: This study shows no evidence for a disturbed DEX/CRF test as a state-independent factor in recurrent MDD on a group level. However, MDD is a complex and heterogenic disorder. Probably, there is a subgroup of patients who show a disturbed DEX/CRF test due to an inherited and/or acquired predisposition or as a biological scar after previous depressive episodes.

The use of atypical antipsychotics in the treatment of catatonia.

PURPOSE: Evidence indicates that classical antipsychotics may aggravate non-malignant and malignant catatonia (MC). Atypical antipsychotics are less likely to cause movement disorders than classical antipsychotics and they are being frequently prescribed in disorders that can be associated with catatonia. Therefore, the important question that arises is whether atypical antipsychotics have a role to play in the treatment of catatonia. MATERIALS AND METHODS: A Medline search was performed to locate papers on the use of atypical antipsychotics in catatonia published between 1970 and 31st December 2004. RESULTS: The literature on the use of atypical antipsychotics in catatonia consists of case reports and retrospective studies. In most cases of non-MC a reduction of the catatonic symptoms is reported upon treatment with atypical antipsychotics. Cases of MC relate mainly to the neuroleptic malignant syndrome (NMS), which is considered as an iatrogenic stuporous variant of MC caused by antipsychotics. CONCLUSION: There are indications that atypical antipsychotics may be useful in non-MC. As a consequence, one should not only focus on the possible extrapyramidal and autonomic side effects of these drugs, but also on the possible beneficial effects on certain brain functions and on the catatonic symptomatology. However, randomized controlled trials are needed to evaluate the effect of these drugs, and caution is advisable, since cases of NMS have been linked to treatment with atypical antipsychotics. There is no evidence to prescribe atypical antipsychotics in MC.

Neutral reagents in solutions with low content of supporting electrolyte: how to determine the steady-state conditions.

Cyclic voltammograms obtained at ultramicroelectrodes in the electrochemical systems where an uncharged reactant is significantly more concentrated than the supporting electrolyte show an unusual feature. The forward and the backward waves cross over, forming a hysteresis loop. The width of the hysteresis increases with the relative concentration of the reactant, with the electrode size, and with the scan rate. We show that the reason for this hysteresis is the slow transport of supporting electrolyte ions that are necessary to compensate the charge of the reaction product. As a result, the steady-state concentration profile of counterions is reached significantly slower than the steady-state concentration gradient of the reactant, and the counterion transport determines how rapidly the steady state for the whole system is approached. The scan rate yielding near-steady-state voltammograms can differ by more than 1 order of magnitude for systems with high and low concentrations of supporting electrolyte. Experimental evidence for this, supported by digital simulation results, is presented. The appropriate criterion for assessing the steady state in such systems is thus the identity of the forward and backward scans, without hysteresis. If this condition is not fulfilled, the formal potentials and the related parameters determined from the obtained voltammograms may be erroneous.

Numerical investigation of transient current density distributions for multi-ion electrolytes at a rotating disk electrode.

A versatile model for the simulation of transient multiion transport and reaction processes is applied to investigate current density distributions over a rotating disk electrode for linear voltammetric sweep experiments. The model accounts for ion transport by convection, diffusion, and migration, in combination with Butler-Volmer type electrode reactions. For several process conditions (reversible and irreversible reactions, excess or lack of supporting electrolyte), the current density distribution over the disk surface is examined and the transient current response is compared to results from the more commonly used one-dimensional axial approach. The impact of migrational effects on the nonuniform local process conditions over the disk surface is illustrated, and the resulting effect on the current peak height, width, and position is investigated. A mathematical correlation for the current peak height as a function of the reacting ion transference number is established.

Numerical solution of a multi-ion one-potential model for electroosmotic flow in two-dimensional rectangular microchannels.

A new more general numerical model for the simulation of electrokinetic flow in rectangular microchannels is presented. The model is based on the dilute solution model and the Navier-Stokes equations and has been implemented in a finite-element-based C++ code. The model includes the ion distribution in the Helmholtz double layer and considers only one single electrical' potential field variable throughout the domain. On a charged surface(s) the surface charge density, which is proportional to the local electrical field, is imposed. The zeta potential results, then, from this boundary condition and depends on concentrations, temperature, ion valence, molecular diffusion coefficients, and geometric conditions. Validation cases show that the model predicts accurately known analytical results, also for geometries having dimensions comparable to the Debye length. As a final study, the electro-osmotic flow in a controlled cross channel is investigated.