Activation of cyclic AMP pathway prevents CD34(+) cell apoptosis

OBJECTIVE: Although cAMP is involved in a number of physiologic functions, its role in hematopoietic cell fate decision remains poorly understood. We have recently demonstrated that in CD34(+)-derived megakaryocytes, cAMP-related agents prevent apoptosis. In this study we addressed the question of whether cAMP also regulates survival of their precursors, CD34(+) cells. METHODS: Apoptosis was evaluated by fluorescence microscopy, and detection of hypodiploid or annexin V(+) cells by flow cytometry. Mitochondrial membrane potential and bcl-xL or caspase-3 expression were assessed by flow cytometry. Colony-forming units were studied by clonogenic assays in methylcellulose. RESULTS: We found that two different cAMP analogs such as Dibutiril-cAMP and sp-5,6-DCl-BIMPS (BIMPS) promoted survival of human umbilical cord-derived CD34(+) cells by suppressing apoptosis induced by either nitric oxide (NO) or serum deprivation. Involvement of PKA and PI3K pathway was demonstrated by the ability of their specific inhibitors Rp-cAMP and Wortmannin or LY294002 respectively to reverse the antiapoptotic effect of BIMPS. Treatment of CD34(+) cell with BIMPS not only restrained the bcl-xL downregulation but also suppressed the loss of mitochondrial membrane potential and caspase-3 activation induced by serum starvation. While thrombopoietin (TPO), granulocyte colony-stimulating factor (G-CSF) or stem cell factor (SCF) were not able to increase cAMP levels, the antiapoptotic activity exerted by these growth factors was blocked by inhibition of the adenylate cyclase and synergized by BIMPS. Cyclic AMP analogs suppressed the decreased colony formation in cells exposed to NO or serum deprivation. CONCLUSION: Altogether, our results strongly suggest that cAMP appears to be not only a key pathway controlling CD34(+) survival, but also a mediator of the TPO-, G-CSF- and SCF-mediated cytoprotection.     

Combined antiviral-immunosuppressive treatment in human T-lymphotrophic virus 1-Sjögren-associated myelopathy

BACKGROUND: In several studies, antiretroviral drugs (principally zidovudine) have been used with success in the treatment of myelopathy associated with human T-lymphotrophic virus 1 (HTLV-1) (tropical spastic paraparesis-HTLV-1-associated myelopathy). The retrovirus HTLV-1 has been implicated as a causative agent of Sj?gren syndrome (SS) in clinical reports and murine experiments. Moreover, a recognized complication of primary SS is a myelopathy, which has been shown in case reports to respond to immunosuppressive treatment. OBJECTIVE: To describe a patient with a rapidly progressive, extensive myelopathy with evidence of HTLV-1 infection and SS (probably secondary to HTLV-1) in whom we achieved spectacular therapeutic success using combined immunosuppressive and antiviral therapy. DESIGN: Case report. SETTING: University hospital.Patient A young Haitian woman diagnosed with HTLV-1 and SS developed extensive myelopathy leading to severe disability. MAIN OUTCOME MEASURES: Clinical and radiological improvement. RESULTS: Spectacular radiological and clinical recovery as well as stabilization were achieved with combined antiviral and immunosuppressant treatment. Follow-up at 2 years showed no signs of relapse. CONCLUSIONS: Both tropical spastic paraparesis-HTLV-1-associated myelopathy and Sj?gren myelopathy are potentially very disabling. Rapidly progressive myelopathy secondary to SS necessitates the introduction of immunosuppressant therapies. The presence of HTLV-1 may confer the necessity to add antiviral therapy.     

The age-related changes in the incidence of 'natural' anti-sperm antibodies suggest they are not auto-/isoantibodies

PROBLEM: Establishing the age-dependent patterns of sperm antibody levels among normal humans. METHODS OF STUDY: Sera samples from 498 healthy subjects aged 0-97 years - 246 males and 252 females - were tested by the gelatin agglutination test of Kibrick, tray agglutination test of Friberg, sperm immobilization test of Isojima and enzyme-linked immunosorbent assay (ELISA). RESULTS: We found a significant increase in the level of sperm agglutinins after 40 years, which decreased after 88 years. The antibodies detected by ELISA were the highest among prepubertal subjects and also declined with aging. No age-dependent changes were established for the sperm immobilizins. With few exceptions, there were no significant differences between male and female sera, as well as between sera of newborn and their mothers. CONCLUSIONS: These data are similar to those established for the age-dependent changes of antibodies towards exogenous antigens, suggesting that the 'naturally occurring' antibodies against human spermatozoa are not auto-/isoantibodies.     

Dysfunctional supplementary motor area implication during attention and time estimation tasks in schizophrenia: a PET-O15 water study

Results of this PET-O15 water activation study confirm the implication of supplementary motor areas during time estimation tasks. They also show that the cortical-subcortical network associated with temporal processing is impaired in schizophrenia. Following recent proposals of time dynamic networks, this impairment may consist in a dysfunctional imbalance of early failure of supplementary motor activation during temporal processing.     

Inositol (1,4,5)-trisphosphate dynamics and intracellular calcium oscillations in pancreatic beta-cells

Glucose-stimulated insulin secretion is associated with transients of intracellular calcium concentration ([Ca2+]i) in the pancreatic beta-cell. We tested the hypothesis that inositol (1,4,5)-trisphosphate [Ins(1,4,5)P3] [Ca2+]i release is incorporated in glucose-induced [Ca2+]i oscillations in mouse islets and MIN6 cells. We found that depletion of intracellular Ca2+ stores with thapsigargin increased the oscillation frequency by twofold and inhibited the slow recovery phase of [Ca2+]i oscillations. We employed a pleckstrin homology domain-containing fluorescent biosensor, phospholipase C partial differential pleckstrin homology domain-enhanced green fluorescent protein, to visualize Ins(1,4,5)P3 dynamics in insulin-secreting MIN6 cells and mouse islets in real time using a video-rate confocal system. In both types of cells, stimulation with carbamoylcholine (CCh) and depolarization with KCl results in an increase in Ins(1,4,5)P3 accumulation in the cytoplasm. When stimulated with glucose, the Ins(1,4,5)P3 concentration in the cytoplasm oscillates in parallel with oscillations of [Ca2+]i. Maximal accumulation of Ins(1,4,5)P3 in these oscillations coincides with the peak of [Ca2+]i and tracks changes in frequencies induced by the voltage-gated K+ channel blockade. We show that Ins(1,4,5)P3 release in insulin-secreting cells can be stimulated by depolarization-induced Ca2+ flux. We conclude that Ins(1,4,5)P3 concentration oscillates in parallel with [Ca2+]i in response to glucose stimulation, but it is not the driving force for [Ca2+]i oscillations.     

Polyamines antagonizing angiotensin II contractile effects in isolated rat aorta

Our study showed that the administration in pre-treatment of some polyamines (especially spermine and spermidine and almost null agmatine, putrescine and cadaverine) reduced the contractile effects of angiotensin II (Ang II) in isolated rat aorta. These effects might not be associated to the interference of clathrin coated vesicles (coated pits) formation or caveolae interaction (and thus to Ang II internalization through AT1 receptors). In contrast, these effects seem to be due to the interaction with voltage-gated membrane Ca2+ channels. Therefore, the alteration of transmembrane Ca2+ fluxes does not exclude the involvement of internalization process through coated pits or caveolae, since the endocytosis mediated by these phenomena essentially needs Ca2+. In addition, the inhibitory effects are dependent on the number of positive charges of the polyamine molecules.