Previous studies have demonstrated that multiple agents that promote survival of PC12 cells and sympathetic neurons deprived of trophic support also block cell cycle progression. Presently, we ...address whether inhibition of cell cycle-related cyclin-dependent kinases (CDKs) prevents neuronal cell death. We show that two distinct CDK inhibitors, flavopiridol and olomoucine, suppress the death of neuronal PC12 cells and sympathetic neurons. In addition, we demonstrate that inhibitor concentrations required to promote survival correlate with their ability to inhibit proliferation. Promotion of survival, however, does not correlate with inhibition of extracellular signal-regulated kinase or c-Jun kinase activities or with interference with the activation of c-Jun kinase that accompanies serum/nerve growth factor deprivation. In contrast to their actions on nerve growth factor-differentiated PC12 cells, the CDK inhibitors do not prevent the death of proliferation-competent PC12 cells and, in fact, promote their cell death. These findings support the hypothesis that post-mitotic neuronal cells die after removal of trophic support due to an attempt to re-enter the cell cycle in an uncoordinated and inappropriate manner. We speculate that cycling PC12 cells are not saved by these agents due to a signaling conflict between an inherent oncogenic signal and the inhibition of CDK activity.
To evaluate the clinical and economical impact of a fast-track anaesthesia protocol in the management of primary varicose vein (VV) surgery.
Over a 10-month period (from 1 December 2009 to 30 ...September 2011), all patients eligible for open VV surgery (N = 176) were enrolled in a fast-track clinical pathway including titrated analgo-sedation combined with local anaesthesia. This fast-track cohort was compared with a historical cohort undergoing similar procedures and receiving general anaesthesia (GA) or spinal anaesthesia (SA) (between 1 December 2009 to 30 September 2011, N = 200). The length of stay in the operating facilities and postoperative recovery areas were reported and hospital costs were estimated. In addition, the occurrence of adverse events and unplanned hospital admission were compared between the two consecutive periods.
Patients characteristics and surgical procedure were not different in the two cohorts. After implementation of the fast-track pathway, the incidence of postoperative adverse events decreased from 41% to 2.3%, with no need for overnight hospital stay (0% versus 7%). The reduction in anaesthesia-controlled time (-47%) and in postoperative recovery time (-61%) were associated with an increased operating capacity (1 extra case per day) and with substantial cost-savings (mean reduction of €312 per case, P < 0.001).
Implementation of a fast-track pathway for outpatient VV surgery was successful, safe and efficient. Analgo-sedation combined with infiltrative anaesthesia (instead of GA or SA) contributed to increase the operating capacity and to reduce the workload of nursing personnel.
We have used cultured PC12 cells and rat sympathetic neurons as model systems to examine the regulation of neuronal cell death and survival. Because nitric oxide (NO) may be involved in nerve growth ...factor (NGF) signaling in PC12 cells, we tested NO-generating compounds for their ability to protect PC12 cells and sympathetic neurons from death after withdrawal of trophic support. Three such agents, S-nitroso-N-acetylpenicillamine (SNAP), diethylenetriamine NO adduct (DETA-NO), and sodium nitroprusside provide (SNP), were found to promote complete short-term survival after removal of serum from naive PC12 cells and of NGF from neuronally differentiated PC12 cells and sympathetic neurons. One major target of NO action is guanylate cyclase, which is activated by nitrosylation of its heme prosthetic group. We observed that inhibition of guanylate cyclase blocks the protective effects of the NO generators on trophic factor-deprived PC12 cells and sympathetic neurons without preventing NGF-induced survival. We also found that permeant cGMP analogs and an inhibitor of cGMP-specific phosphodiesterase enhance cell survival, suggesting that the protective effects of NO are mediated by activation of guanylate cyclase and increased intracellular cGMP. N-Nitro-L-arginine methyl ester, a NO synthase inhibitor, did not block NGF-promoted PC12 cell or sympathetic neuron survival. These findings indicate that like NGF, NO has survival-promoting actions on neurons but that the two agents work by initially independent mechanisms.
In the present study, we tested whether apoptotic neuronal death caused by withdrawal of trophic support might be prevented by agents that block cell cycle progression. We used three complementary ...model systems that exhibit apoptotic death: dividing PC12 cells deprived of nerve growth factor (NGF); and primary cultures of postmitotic sympathetic neurons deprived of NGF. We show that cell death in each case can be suppressed by treatment with the G1/S blockers mimosine, ciclopirox, and deferoxamine at concentrations that correlate with their abilities to block PC12 cell proliferation. In contrast, agents that block cell cycle progression in the S-, G2-, or M-phase do not prevent cell death. These observations support the hypothesis that removal of trophic support from dividing or postmitotic neuronal cells provokes their apoptotic death by causing them either to proceed through or to attempt to re-enter an uncoordinated and consequently fatal cell cycle. Moreover, the data suggest that simply blocking the cycle at any point is not protective but, rather, that it is necessary to block at specific "safe" points. This study defines a safe point in the cell cycle before the G1/S transition that is demarcated by the action of these three agents.
We report that dipyridamole is neuroprotective for a variety of rat embryonic CNS neurons cultured in serum-free basal medium lacking trophic factors or other additives. We also describe the ...mechanism underlying this action. Neurons died rapidly in basal medium but were rescued in large measure by 10 microM dipyridamole. The protective action of dipyridamole seems to be attributable to its antioxidant property. Vitamin E and N-acetylcysteine provided comparable neuroprotection in basal medium, whereas an array of compounds that mimic other actions of dipyridamole (inhibition of phosphodiesterases, blockade of nucleoside and chloride transport, interference with the multidrug resistance protein, and enhancement of prostacyclin synthesis) failed to promote survival. Thus, a major cause of neuronal death in this system seems to be oxidative stress that is relieved by dipyridamole. Iron plays a significant role in generation of such stress, as indicated by the observations that addition of apotransferrin or iron chelators to basal medium or use of iron-free medium also afforded protection. Although oxidative stress was a major determinant of neuronal death, it was not the only factor. Dipyridamole or other antioxidant measures did not provide sustained neuroprotection. However, provision of insulin, which was not protective alone in basal medium, along with dipyridamole significantly enhanced long-term neuronal survival. Hence, optimal protection requires both trophic support and relief from oxidative stress. These findings lend credence to the potential use of dipyridamole or its derivatives in prevention and/or treatment of CNS injuries and degenerative disorders in which oxidative stress is a significant component.
Background
: Allopregnanolone, a neuroactive steroid mainly secreted by adrenals and gonads, is a hormone that seems to play a role in precocious puberty, as demonstrated by its high baseline levels ...found in girls with central precocious puberty (CPP). Allopregnanolone concentrations significantly increase after GnRH and ACTH stimulation test suggesting both its ovarian and adrenal production.
Aim
: Aim of this study was to evaluate allopregnanolone concentrations after GnRH and GnRH agonist analog stimulation test in girls with CPP to better establish its secretion source.
Subjects and methods
: Gonadotropins and steroid hormones were evaluated in different days after GnRH and triptorelin stimulation test in 15 CPP girls.
Results
: After GnRH stimulation, LH, FSH, and allopregnanolone concentrations significantly increased (
p
<0.05). After triptorelin administration LH, FSH, estradiol and DHEAS levels significantly increased (
p
<0.05), while allopregnanolone concentrations significantly decreased (1.08±0.24
vs
0.87±0.28 nmol/l;
p
=0.003).
Conclusions
: The different response of allopregnanolone to GnRH and GnRH agonist analog might reflect the agonist and antagonist action exerted by these secretagogues. Our data suggest the prevalent gonadal allopregnanolone production in CPP subjects and the usefulness of its measurement in the diagnosis of CPP.
Previous studies indicate that activation of c-Jun kinase (JNK) is necessary for apoptosis of trophic factor-deprived PC12 cells and that death in this system is suppressed by multiple agents, ...including BCL2, inhibitors of the interleukin-1-converting enzyme (ICE) family of proteases, blockers of transcription, and a variety of small molecules with differing modes of action. Here, we determine the order in which these agents block apoptosis relative to JNK activation. Overexpression of BCL2 promotes PC12 cell survival and blocks JNK activation caused by trophic factor withdrawal. Similarly, the survival-promoting agents aurintricarboxylic acid, N-acetylcysteine, the nitric oxide generator diethylenetriamine nitric oxide, 8-bromo-cGMP, and 8-(4-chlorophenylthio)-cAMP act upstream to inhibit JNK activation. In contrast, zVAD-fluoromethylketone (a permeant ICE family inhibitor), actinomycin D, and the G1/S cell cycle inhibitor deferoxamine, all promote survival after trophic factor withdrawal, but do not affect JNK activation. These findings are consistent with the presence of an ordered cell death pathway triggered by trophic factor deprivation in which 1) BCL2 and a number of survival-promoting agents act upstream of JNK, 2) ICE family protease actions, regulated genes required for cell death, and certain cell cycle blockers lie either downstream of JNK or on independent pathways required for apoptotic death.
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