Clinical evaluation of switching from immediate-release to prolonged-release lithium in bipolar patients, poorly tolerant to lithium immediate-release treatment: A randomized clinical trial

AIM

The effect of switching from lithium immediate release (Li-IR) to lithium prolonged release (Li-PR) on lithium-induced tremor after 1 and 12 weeks of treatment was evaluated in a randomized, multicenter, open trial, in bipolar patients from the participating sites with a tremor severity ≥2 (Udvalg for Kliniske Undersøgelser [UKU] rating scale) despite optimal lithium titration.

METHODS

The primary endpoint was the evaluation of tremor by means of the UKU scale after 1 week of treatment. Secondary endpoints included manic Young Mania Rating Scale (YMRS) and depressive symptoms (Montgomery-Asberg Depression Rating Scale), a global assessment of the patient's status (Clinical Global Impression), polyuria/polydipsia (UKU item 3.8) and patient-reported outcomes.

RESULTS

Owing to difficulties in including suitable patients the enrollment phase was closed when 73 patients were randomized. Notwithstanding the lower number of patients, in the modified intention-to-treat population (n = 70) the primary endpoint was statistically significant: tremor improved after 1 week in 62.9% in Li-PR group against 20.0% of patients in Li-IR group (p = .0006; two-tailed Fisher's exact test). The difference remained statistically significant after 4 (p = .0031) and 12 weeks (p = .0128). The same analysis performed in the PP population confirmed these results. Among the secondary endpoints, only the factor convenience of the treatment satisfaction questionnaire showed a statistically significant difference between groups. There were no apparent differences in the safety profile of the two formulations.

CONCLUSIONS

This study is the first comparative documentation of a potential benefit of the prolonged-release formulation in reducing the symptom tremor, a well-known adverse effect of lithium therapy. Indeed, the study results should be interpreted taking into account the sample size lower than planned.

NGF-withdrawal induces apoptosis in pancreatic beta cells in vitro

AIMS/HYPOTHESIS

Using primary cultures of human pancreatic islets, purified human pancreatic beta cells and the mouse beta TC6-F7 cell line, we analysed the expression of nerve growth factor, (NGF/NGF) receptors in beta cells. To investigate whether NGF could sub-serve an autocrine antiapoptotic role in beta cells, we studied the effects of NGF withdrawal using a neutralizing monoclonal anti-NGF antibody.

METHODS

The expression of NGF and NGF receptors (gp140(Trk-A) and p75(NTR)) were analysed by RT-PCR and immunofluorescence. Pulse-chase experiments and beta cell/PC12 co-cultures were used to investigate NGF production and secretion from beta cells. Possible apoptosis induced by NGF withdrawal was monitored by phosphatidylserine translocation, nucleosomal formation, DNA laddering and FACS analysis. Involvement of transcription/translation mechanisms were investigated as well as the gp140(Trk-A) required. Finally, signal transduction pathways typically involved in apoptotic mechanisms were analysed by western blot analysis.

RESULTS

We show that NGF and both NGF receptors, gp140(Trk-A) and p75(NTR) are expressed in beta cells where NGF is produced and secreted in a biologically active form. NGF-withdrawal induces beta-cell transcription/translation independent apoptosis but mediated by gp140(Trk-A). Analysis of signal transduction pathways revealed that NGF withdrawal inhibits the PI3-K, protein kinase B (AKT), Bad survival pathway and activates c-Jun kinase (JNK) whereas ERKs and p38 mitogen-activated protein kinase (MAPK) are not affected. Moreover, Bcl-XL, but not Bcl-2 protein expression are reduced.

CONCLUSION/INTERPRETATION

We suggest that the integrity of the NGF/NGF receptor system and NGF bioavailability participate in controlling beta-cell survival in culture which represents a key issue for improving possibilities for transplantations in the treatment of diabetes.

Neurotrophins and neurotrophin receptors mRNAs expression in pancreatic islets and insulinoma cell lines

CONTEXT

It is worth noting that islets and betaTC6-F7 cells share a common pattern of expression of neurotrophins and neurotrophin receptors. Recently, several studies have hypothesized a role for nerve growth factor in pancreatic development and maturation, suggesting that nerve growth factor may be a survival factor for pancreatic beta-cells.

OBJECTIVE

The aim of the present study was to investigate the pattern of expression of neurotrophins and their relative receptors both in rat pancreatic islets and in a wide panel of insulinoma cell lines.

MAIN OUTCOME MEASURES

A semi-quantitative reverse-transcription polymerase chain reaction analysis was performed on ribonucleic acids extracted from these cells.

RESULTS

Reverse transcription-polymerase chain reaction analysis demonstrates that brain-derived neurotrophic factor, as well as neurotrophins 3 and 4, are expressed both in islets and in all insulinoma cells, while nerve growth factor is expressed only in islets, betaTC6-F7 cells and, at a low level, in RIN 1046-38 cells. Receptors protein tyrosine kinase A and C are ubiquitously expressed both in islets and insulinoma cells. Tyrosine kinase B is absent in HIT-T15 cells.

CONCLUSIONS

These data indicate that betaTC6-F7 cells are a suitable model for studying the role of neurotrophins in the survival of beta-cells.

Intracellular localization and isoform expression of the voltage-dependent anion channel (VDAC) in normal and dystrophic skeletal muscle

Voltage-dependent anion channels (VDACs) are a family of pore-forming proteins encoded by different genes, with at least three protein products expressed in mammalian tissues. The major recognized functional role of VDACs is to permit the almost free permeability of the outer mitochondrial membrane (OMM). Although VDAC1 is the best known among VDAC isoforms, its exclusively mitochondrial location is still debated. Therefore, we have measured its co-localization with markers of cellular organelles or compartments in skeletal muscle fibers by single or double immunofluorescence and traditional as well as confocal microscopy. Our results show that VDAC1 immunoreactivity corresponds to mitochondria and sarcoplasmic reticulum, while sarcolemmal reactivity, previously reported, was not observed. Since VDAC1 has been suggested to be involved in the control of oxidative phosphorylation, we sought for possible gene regulation of VDAC1, VDAC2 and VDAC3 in skeletal muscle of the dystrophin-deficient mdx mouse, which suffers of an impaired control of energy metabolism. Our results show that, while VDAC1 mRNA and protein and VDAC2 mRNA are normally expressed. VDAC3 mRNA is markedly down-regulated in mdx mouse muscle at different ages (before, during and after the outburst of myofiber necrosis). This finding suggests a possible involvement of VDAC3 expression in the early pathogenic events of the mdx muscular dystrophy.

Molecular and functional characterization of pituitary adenylate cyclase-activating polypeptide (PACAP-38)/vasoactive intestinal polypeptide receptors in pancreatic beta-cells and effects of PACAP-38 on components of the insulin secretory system

It has been previously demonstrated that pituitary adenylate cyclase-activating polypeptide (PACAP) regulates insulin secretion. PACAP exerts its biological action by binding to at least three different receptor subtypes coupled to different signal transduction mechanisms. The signaling pathways underlying the insulinotropic effect of PACAP involve mainly the activation of adenylate cyclase to form cAMP, which directly and indirectly, through increased intracellular Ca2+, stimulates insulin exocytosis. In the present study we have characterized the functional and molecular expression of PACAP/vasoactive intestinal polypeptide receptors isoforms and subtypes and its isoforms in a beta-cell line and in isolated rat pancreatic islets. Although insulinoma cells express the messenger RNA encoding PAC1 (-R and -hop variants), VPAC1 and VPAC2, binding experiments indicate the preponderance of PAC1 over VPAC 1-2 receptors. We have also shown that the main signaling pathway of PACAP in beta-cells is mediated by adenylate cyclase, whereas the inositol 1,4,5-trisphosphate pathway is almost inactive. Furthermore, we have demonstrated that PACAP exerts long-term effects on beta-cells, such as transcriptional regulation of the insulin gene and genes of the glucose-sensing system (GLUT1 and hexokinase 1).