Cellular transformation and activation of the phosphoinositide-3-kinase-Akt cascade by the ETV6-NTRK3 chimeric tyrosine kinase requires c-Src

The ETV6-NTRK3 (EN) chimeric tyrosine kinase, a potent oncoprotein expressed in tumors derived from multiple cell lineages, functions as a constitutively active protein-tyrosine kinase. ETV6-NTRK expression leads to the constitutive activation of two major effector pathways of wild-type NTRK3, namely, the Ras-mitogen-activated protein kinase (MAPK) mitogenic pathway and the phosphoinositide-3-kinase (PI3K)-Akt pathway mediating cell survival, and both are required for EN transformation. However, it remains unclear how ETV6-NTRK3 activates Ras-Erk1/2 and/or PI3K-Akt cascades. Here, we define some aspects of the molecular mechanisms regulating ETV6-NTRK-dependent Ras-Erk1/2 and PI3K-Akt activation. We show that ETV6-NTRK3 associates with c-Src, and that treatment with SU6656, a c-Src inhibitor, completely blocks ETV6-NTRK-transforming activity. Treatment of NIH3T3 cells expressing ETV6-NTRK3 with SU6656 attenuated the activation of Ras-Erk1/2 and PI3K-Akt. Suppression of c-Src by RNA interference in NIH3T3-ETV6-NTRK3 cells resulted in markedly decreased expression of cyclin D1 and suppression of activation of Ras-Erk1/2 and PI3K-Akt. However, in Src-deficient cells, the ETV6-NTRK3 failed to activate the PI3K-Atk pathway, but not the Ras-Erk1/2 pathway. Therefore, these data indicate that ETV6-NTRK3 induces the PI3K-Akt cascade through the activation of c-Src.     

Predictors of poor adherence to medication among patients with first-episode schizophrenia-spectrum disorder

Aim: This study sought to identify predictors for poor adherence to medication among patients with first‐episode schizophrenia‐spectrum disorder. Methods: Medication adherence was measured 1 and 2 years after initiation of antipsychotic medication in a follow‐up study of 547 patients. Relevant variables were systematically assessed at baseline, 1‐ and 2‐year follow up. Results: Most patients have difficulties with medication adherence over time. Negative attitudes towardsmedication and lack of consistent family support are the strongest predictors for poor adherence to medication for first‐episode psychotic patients in the first 2 years. After 1 year of treatment, unawareness of the effect of medication, lack of positive attitudes towards medication, substance abuse, young age and high global functioning also predict poor adherence to medication. Conclusions: A number of variables were independently associated with poor adherence. Rating of insight and attitudes towards medication makes it possible to predict poor adherence in incident cases with schizophrenia.     

17β‐estradiol regulation of the mRNA expression of t‐type calcium channel subunits: Role of estrogen receptor α and estrogen receptor β

Low‐voltage‐activated (T‐type) calcium channels are responsible for burst firing and transmitter release in neurons and are important for exocytosis and hormone secretion in pituitary cells. T‐type channels contain an α1 subunit, of which there are three subtypes, Cav3.1, ‐3.2, and ‐3.3, and each subtype has distinct kinetic characteristics. Although 17β‐estradiol (E2) modulates T‐type calcium channel expression and function, little is known about the molecular mechanisms involved. We used real‐time PCR quantification of RNA extracted from hypothalamic nuclei and pituitary in vehicle and E2‐treated C57BL/6 mice to elucidate E2‐mediated regulation of Cav3.1, ‐3.2, and ‐3.3 subunits. The three subunits were expressed in both the hypothalamus and the pituitary. E2 treatment increased the mRNA expression of Cav3.1 and ‐3.2, but not Cav3.3, in the medial preoptic area and the arcuate nucleus. In the pituitary, Cav3.1 was increased with E2 treatment, and Cav3.2 and ‐3.3 were decreased. To examine whether the classical estrogen receptors (ERs) were involved in the regulation, we used ERα‐ and ERβ‐deficient C57BL/6 mice and explored the effects of E2 on T‐type channel subtypes. Indeed, we found that the E2‐induced increase in Cav3.1 in the hypothalamus was dependent on ERα, whereas the E2 effect on Cav3.2 was dependent on both ERα and ERβ. However, the E2‐induced effects in the pituitary were dependent on only the expression of ERα. The robust E2 regulation of T‐type calcium channels could be an important mechanism by which E2 increases the excitability of hypothalamic neurons and modulates pituitary secretion. J. Comp. Neurol. 512:347–358, 2009. © 2008 Wiley‐Liss, Inc.     

Kinetic characterization of VIM-7, a divergent member of the VIM metallo-beta-lactamase family

Purified recombinant VIM-7 possesses efficient penicillinase and carbapenemase activities comparable to those of VIM-2. Cephalosporinase activity was variable and generally lower than those of VIM-1 and VIM-2. A homology model suggests that the VIM-7 Tyr-218 Phe substitution may be responsible for the reduced catalytic efficiency against certain cephalosporins, including ceftazidime and cefepime.     

Expression of glutamine synthetase and glutamate dehydrogenase in the latent phase and chronic phase in the kainate model of temporal lobe epilepsy

It has been suggested that astrocytic glutamate release or perturbed glutamate metabolism contributes to the proneness to epileptic seizures. Here we investigated whether astrocytic contents of the major glutamate degrading enzymes glutamine synthetase (GS) and glutamate dehydrogenase (GDH) decreases on moving from the latent phase (prior to seizures) to the chronic phase (after onset of seizures) in the kainate (KA) model of temporal lobe epilepsy. Western blotting and immunogold analysis of hippocampal formation indicated similar levels of GDH in the latent and chronic phases of KA injected rats and in corresponding controls. In contrast, the level of GS was increased in the latent phase compared with controls, as assessed by Western blots of whole hippocampal formation and subregions. The increase in GS paralleled that of glial fibrillary acidic protein (GFAP). Compared with the latent phase, the chronic phase revealed a lower level of GS (approaching control levels) but an unchanged GFAP content. The decrease in GS from latent to chronic phase was significant in whole hippocampal formation, dentate gyrus and CA3. It is concluded that kainate treated rats show an initial increase in GS, pari passu with the increase in GFAP, and a secondary decrease in GS that is not accompanied by a similar loss of GFAP. In a situation where glutamate catabolism is in high demand the secondary reduction in GS level may be sufficient to contribute to the seizure proneness that develops between the latent and chronic phases.     

Does a detection team shorten duration of untreated psychosis?

Introduction: Duration of untreated psychosis (DUP) is shown to be associated with poor outcome in many domains. It has been shown that it is possible to shorten DUP when combining a detection team and an information campaign. The aim of this study was to evaluate whether DUP was shortened during the first 3 years after establishing detection teams without a concomitant information campaign. Methods: All patients included in the OPUS trial were examined with the Instrument for Retrospective Assessment of Onset of Psychosis to determine DUP. A total of 552 patients with first episode psychotic disorder (n = 470) or schizotypal disorder (n = 82) were included in the study. The 3‐year inclusion period was divided into six consecutive periods of 6 months each. Results: The median DUP was 52 weeks. DUP was not significantly reduced during the 3‐year inclusion period, but a larger proportion of patients with symptoms below the threshold for frank psychosis were included compared with the beginning of the trial. The proportion referred from primary care remained small (8–10%) and unchanged during the inclusion period. Discussion: The availability of a detection team increased the referral of patients with schizotypal disorder, but the DUP among psychotic patients remained almost unaltered throughout the period. It seems that an information campaign and possibilities for direct access and self‐referral are necessary in order to shorten DUP.     

Role of inflammation in the progression of heart failure

Chronic heart failure (HF) is a disorder characterized in part by immune activation and inflammation. Thus, patients with HF have elevated levels of a number of inflammatory cytokines, both in the circulation and in the failing heart itself. Several mechanisms for this immune activation, which are not mutually exclusive, have been suggested, including neurohormonal activation, hemodynamic overload, and activation of the innate immune system secondary to cardiac stress. Importantly, experimental studies have shown that inflammatory cytokines such as tumor necrosis factor-alpha, interleukin-1b, and monocyte chemoattractant peptide-1 may contribute to the development and progression of HF by promoting myocardial hypertrophy, activating matrix metalloproteinases, provoking contractile dysfunction, and inducing apoptosis. However, inflammatory cytokines may also have adaptive and cardioprotective effects. This important aspect of cytokine biology must be kept in mind when designing new immunomodulatory treatment modalities in HF.