Pain reduction with an immersive digital therapeutic in women suffering from endometriosis-related pelvic pain: a randomized, controlled, open-label, two-parallel-group, interventional pilot study (Preprint)

Background

Objective

Methods

Results

Conclusions

Trial Registration

Chronic Heart Failure Model Induced by Coronary Embolization in Sheep

Objective

To create a model of chronic heart failure in a large animal.

Methods

Heart failure was induced in sheep by single intracoronary injection of polymer macrobeads, which were administered into left main coronary artery (n=3) or selectively into left anterior descending (n=4) or left circumflex (n=5) coronary artery. The animals were followed by echocardigraphy for 20 weeks. Measurements comprised fractional area change (FAC), and diastolic ventricular area (EDVA) and regional wall-thickening fraction (WT%).

Results

EDVA increased from 14.2±2.1 cm2 prior to embolization to 16.9±3.1 cm2 on day 1 (p<0.05), and remained significantly increased until completion of the follow-up period. FAC dropped from 47.9±4.6% at baseline to 29.3±4.4% on day 1 (p<0.001) and remained significantly depressed until 20 weeks later. In 9 selectively embolized animals WT% of the embolized area decreased from 33.8±8.0% at baseline to 5.3±2.6% on day 1 and remained significantly decreased.

Conclusions

A simple model of chronic heart failure was developed. It shows relatively high stability over time and may prove beneficial in experimental work on ventricular assist devices.

Differential Kinetics in Alteration and Recovery of Cognitive Processes from a Chronic Sleep Restriction in Young Healthy Men

Chronic sleep restriction (CSR) induces neurobehavioral deficits in young and healthy people with a morning failure of sustained attention process. Testing both the kinetic of failure and recovery of different cognitive processes (i.e., attention, executive) under CSR and their potential links with subject's capacities (stay awake, baseline performance, age) and with some biological markers of stress and anabolism would be useful in order to understand the role of sleep debt on human behavior. Twelve healthy subjects spent 14 days in laboratory with 2 baseline days (B1 and B2, 8 h TIB) followed by 7 days of sleep restriction (SR1-SR7, 4 h TIB), 3 sleep recovery days (R1-R3, 8 h TIB) and two more ones 8 days later (R12-R13). Subjective sleepiness (KSS), maintenance of wakefulness latencies (MWT) were evaluated four times a day (10:00, 12:00 a.m. and 2:00, 4:00 p.m.) and cognitive tests were realized at morning (8:30 a.m.) and evening (6:30 p.m.) sessions during B2, SR1, SR4, SR7, R2, R3 and R13. Saliva (B2, SR7, R2, R13) and blood (B1, SR6, R1, R12) samples were collected in the morning. Cognitive processes were differently impaired and recovered with a more rapid kinetic for sustained attention process. Besides, a significant time of day effect was only evidenced for sustained attention failures that seemed to be related to subject's age and their morning capacity to stay awake. Executive processes were equally disturbed/recovered during the day and this failure/recovery process seemed to be mainly related to baseline subject's performance and to their capacity to stay awake. Morning concentrations of testosterone, cortisol and α-amylase were significantly decreased at SR6-SR7, but were either and respectively early (R1), tardily (after R2) and not at all (R13) recovered. All these results suggest a differential deleterious and restorative effect of CSR on cognition through biological changes of the stress pathway and subject's capacity (ClinicalTrials-NCT01989741).

Effect of Sleep Extension on the Subsequent Testosterone, Cortisol and Prolactin Responses to Total Sleep Deprivation and Recovery

Total sleep deprivation (TSD) in humans is associated with altered hormonal levels, which may have clinical relevance. Less is known about the effect of an extended sleep period before TSD on these hormonal changes. Fourteen subjects participated in two experimental counterbalanced conditions (randomised cross-over design): extended sleep (21.00-07.00 h time in bed, EXT) and habitual sleep (22.30-07.00 h time in bed, HAB). For each condition, subjects performed two consecutive phases: six nights of either EXT or HAB. These nights were followed by 3 days in the sleep laboratory with blood sampling at 07.00 and 17.00 h at baseline (B-07.00 and B-17.00), after 24 and 34 h of continuous awakening (24 h-CA, 34 h-CA) and after one night of recovery sleep (R-07.00 and R-17.00) to assess testosterone, cortisol, prolactin and catecholamines concentrations. At 24 h of awakening, testosterone, cortisol and prolactin concentrations were significantly lower compared to B-07.00 and recovered basal levels after recovery sleep at R-07.00 (P < 0.001 for all). However, no change was observed at 34 h of awakening compared to B-17.00. No effect of sleep extension was observed on testosterone, cortisol and catecholamines concentrations at 24 and 34 h of awakening. However, prolactin concentration was significantly lower in EXT at B-07.00 and R-07.00 compared to HAB (P < 0.05, P < 0.001, respectively). In conclusion, 24 h of awakening inhibited gonadal and adrenal responses in healthy young subjects and this was not observed at 34 h of awakening. Six nights of sleep extension is not sufficient to limit decreased concentrations of testosterone and cortisol at 24 h of awakening but may have an impact on prolactin concentration.

Effects of exercise on brain and peripheral inflammatory biomarkers induced by total sleep deprivation in rats

Background

Physical exercise induces neuroprotection through anti-inflammatory effects and total sleep deprivation is reported an inflammatory process. We examined whether 7 weeks of exercise training attenuates markers of inflammation during total sleep deprivation (24-h wakefulness) in the rat brain and periphery.

Methods

Four groups of 10 rats were investigated: Sedentary control, Sedentary sleep-deprived, Exercised control, and Exercised sleep-deprived. Sleep deprivation and exercise training were induced using slowly rotating wheels and a motorized treadmill. We examined mRNA expression of pro-inflammatory (IL-1β, TNF-α, and IL-6) cytokine-related genes using real-time PCR, and protein levels in the hippocampus and frontal cortex, as well as circulating concentrations.

Results

Compared to Sedentary control rats, hippocampal and cortical IL-1β mRNA expressions in Sedentary sleep-deprived rats were up-regulated (p < 0.05 and p < 0.01 respectively). At the protein level, hippocampal IL-1β and TNF-α and cortical IL-6 contents were higher in Sedentary sleep-deprived rats (p < 0.001, p < 0.05, p < 0.05, respectively). Peripherally, TNF-α, IL-6 and norepinephrine concentrations were higher in Sedentary sleep-deprived rats compared to Sedentary control (p < 0.01, p < 0.001, p < 0.01, respectively). Exercise training reduced the sleep deprivation-induced hippocampal IL-1β increases (mRNA expression and protein content) (p < 0.05 and p < 0.001), and TNF-α content (p < 0.001). At the periphery, exercise reduced sleep deprivation-induced increase of IL-6 concentration (p < 0.05) without effect on TNF-α and norepinephrine.

Conclusions

We demonstrate that a 7-week exercise training program before acute total sleep deprivation prevents pro-inflammatory responses in the rat hippocampus, particularly the IL-1β cytokine at the gene expression level and protein content.

Vascular response to 1 week of sleep restriction in healthy subjects. A metabolic response?

BACKGROUND

Sleep loss may induce endothelial dysfunction, a key factor in cardiovascular risk. We examined the endothelial function during one week of sleep restriction and a recovery period (from 3-to-13 days) in healthy subjects, and its link to autonomic, inflammatory and/or endocrine responses.

METHODS

12 men were followed at baseline (B1, 8-h sleep), after 2 (SR2) and 6 (SR6) days of SR (4-h sleep: 02:00-06:00) and after 1 (R1) and 12 (R12) recovery nights (8h sleep). At 10:00, we assessed changes in: arm cutaneous vascular conductance (CVC) induced by local application of methacholine (MCh), cathodal current (CIV) and heat (44°C), finger CVC and skin temperature (Tfi) during local cold exposure (5°C, 20-min) and passive recovery (22°C, 20-min). Blood samples were collected at 08:00.

RESULTS

Compared with baseline (B1), MCh and heat-induced maximal CVC values (CVC peak) were decreased at SR6 and R1. No effect of SR was observed for Tfi and CVC during immersion whereas these values were lower during passive recovery on SR6 and R1. From SR2 to R12, plasma concentrations of insulin, IGF-1 (total and free) and MCP-1 were significantly increased while those of testosterone and prolactin were decreased. Whole-blood blood mRNA concentrations of TNF-α and IL-1β were higher than B1. No changes in noradrenaline concentrations, heart rate and blood pressure were observed.

CONCLUSIONS

These results demonstrate that SR reduces endothelial-dependent vasodilatation and local tolerance to cold. This endothelial dysfunction is independent of blood pressure and sympathetic activity but associated with inflammatory and metabolic pathway responses (ClinicalTrials-NCT01989741).

Wrist actimetry circadian rhythm as a robust predictor of colorectal cancer patients survival

The disruption of the circadian timing system (CTS), which rhythmically controls cellular metabolism and proliferation, accelerated experimental cancer progression. A measure of CTS function in cancer patients could thus provide novel prediction information for outcomes, and help to identify novel specific therapies. The rest-activity circadian rhythm is a reliable and non-invasive CTS biomarker, which was monitored using a wrist watch accelerometer for 2 days in 436 patients with metastatic colorectal cancer. The relative percentage of activity in-bed versus out-of-bed (I < O) constituted the tested CTS measure, whose prognostic value for overall survival (OS) and progression-free survival (PFS) was determined in a pooled analysis of three patient cohorts with different treatment exposures. Median OS was 21.6 months [17.8-25.5] for patients with I < O above the median value of 97.5% as compared to 11.9 months [10.4-13.3] for those with a lower I < O (Log-rank p < 0.001). Multivariate analyses retained continuous I < O as a joint predictor of both OS and PFS, with respective hazard ratios (HR) of 0.954 (p < 0.001) and 0.970 (p < 0.001) for each 1% increase in I < O. HRs had similar values in all the patient subgroups tested. The circadian physiology biomarker I < O constitutes a robust and independent quantitative predictor of cancer patient outcomes, that can be easily and cost-effectively measured during daily living. Interventional studies involving 24-h schedules of clock-targeted drugs, light intensity, exercise and/or meals are needed for testing the relevance of circadian synchronization for the survival of patients with disrupted rhythms.

Circadian rest-activity rhythm as a predictor of survival in metastatic colorectal cancer

e14006

Background: Experimental disruption of the Circadian Timing System (CTS) accelerates cancer progression. The relative amount of activity in-bed versus out-of-bed (I<O) was identified as a quantitative CTS estimate that predicted survival in two cohorts of patients with metastatic colorectal cancer (CI, CII). Methods: The independent prognostic value of I<O was investigated for Overall Survival (OS) and Progression-Free Survival (PFS) 1) in a new cohort of 142 patients (CIII) receiving circadian-based salvage treatment for metastatic colorectal cancer, and 2) in a pooled population of 436 patients from cohorts I-III. All patients had two-day rest-activity rhythm monitoring and then received a new treatment. Cohort-adjusted data were analyzed with log rank and multivariate Cox analyses. Results: Patients in CIII had poor prognosis disease compared to CI and CII, as assessed by prior chemotherapy (CIII, 69%; CI, 59.5%; CII, none), prior oxaliplatin (CIII, 55%; CII, none; CI, 2%) and/or irinotecan (CIII, 39.4%; CII, none; CI, 7%). The 273 male and 163 female patients in the pooled population had generally good performance status 0 (60.7%) or 1 (33.1%) and 51% had two or more metastatic sites. Following rest-activity rhythm determination, patients received a median of 8 chemotherapy courses. Median OS was 21.6 months [95% Confidence Limits, 17.8 to 25.5] in the patients with I<O above the cutoff median value of 97.5% as compared to 11.9 months [10.4 to 13.3] in those with a lower I<O (p from Log rank < 0.001). The adjusted relative risk related to I<O above cutoff was 0.587 [0.477 to 0.722] for earlier death (p<0.001) and 0.661 [0.542 to 0.807] for earlier progression (p <0.001). Conclusions: The circadian biomarker indicator I<O is a robust and independent quantitative long-term predictor of both OS and PFS in patients with metastatic colorectal cancer. Cancer patients with low I<O could potentially benefit from specific treatments for circadian disruption in order to enhance survival.

The European InCASA telecare-telehealth electronic platform (ICT-FP7) for the daily assessment of symptoms, weight, and activity in cancer patients on chronotherapy at home

TPS9154

Background: Self-rated symptoms contribute to the Quality of Life (QoL) of cancer patients (pts) and impact on prognosis. Behavioural functions are controlled by the circadian timing system (CTS), through a network of molecular clocks that time cellular proliferation and drug metabolism (Lévi et al. ARPT 2010). Chronotherapy aims at the reduction of treatment-related symptoms through the adjustment of chemotherapy delivery to the CTS. Cancer chronotherapy is delivered at home using programmable pumps, and avoids familial and social disruption. Telemedicine tools can provide continuous information on symptoms, behavior, QoL and CTS from non hospitalized pts. Methods: The inCASA platform enables telemonitoring of multiple functions in order to help physicians to detect early warning signals in pt condition at home, and prompt adequate and timely interventions. Our pilot site investigates the clinical relevance of daily teletransmitted self assessed symptoms, body weight and rest-activity circadian rhythm in cancer pts. This system was first well understood and accepted by 14 pts (9 male, 5 female, 43-77 years) at the outpt clinic, then used by 5 pts (4 male, 1 female, 61±13 years) at home daily for 6+ weeks, while receiving chronotherapy. The pilot phase will accrue 30 pts receiving chronotherapy at home from 03/01/2012. Pts will fill in the M.D. Anderson Symptom Inventory scale on a touch-screen device, measure their body weight using a Bluetooth scale and record their circadian rest-activity rhythm using an infrared wrist-watch accelerometer over 6-weeks. The data are transmitted to the platform, then to a web portal with secured access to be daily inspected by the oncology nursing and medical team. The modelling of these continuous records will define alert thresholds for nurse-controlled graded intervention decisions. Conclusion: The assessment criteria set forth for the inCASA solution will address the issues of pt autonomy, CTS entrainment in the pt usual environment, safety of chronotherapy delivery at home and treatment costs. Its use should induce important organisational changes and perception in healthcare professionals.

Circadian robustness as an independent predictor of prolonged progression-free survival (PFS) and overall survival (OS) in 436 patients with metastatic colorectal cancer (mCRC)

464

Background: The rest-activity rhythm is a biomarker of the circadian timing system (CTS), whose disruption accelerates cancer progression in experimental models. Prior studies in cancer pts identified a reliable measure of CTS function in cancer pts based on non invasive wrist actigraphy monitoring.

Methods: The prognostic value of I<O, the ratio between activity counts in-bed vs out-of-bed, was explored for PFS and OS in mCRC. The rest-activity rhythm was recorded for >48 h in 436 mCRC pts from 3 international cohorts. Data were stratified per cohort, and analyzed with Kruskall-Wallis ANOVA, log rank tests, and multivariate Cox analyses.

Results: Median age was 59.2 y. Pts were mainly men (62.6%); had good performance status (PS = 0, 58.2%; 1, 33%); > 2 metastatic sites (51.6%); metastases in liver (79%) or lung (38.8%); were chemotherapy-naïve (54.6%). After baseline actigraphy recording, pts received a median of 8 courses of oxaliplatin- or irinotecan-based chemotherapy, including chronomodulated schedules (chrono; 81.4%). Despite a strong correlation with PS (p< 0.0001), I<O independently influenced both PFS and OS. Thus, both median PFS and OS nearly doubled in the pts with I<O above 97.5% (upper two quartiles) as compared to those with I<O below 93.2% (lowest quartile). Median PFS ranged from 4.8 to 10.6 months (log rank, p<0.001) and median OS from 10.1 to 20.6 months (p<0.001). In multivariate analyses, I<O ranked as the second best independent predictor of PFS, after metastases surgery, with a hazard ratio (HR) of 0.967 [95% C.L., 0.95-0.98] (p<0.001). I<O ranked as first independent predictor of OS, with a HR of 0.95 [0.94-0.97] (p<0.001). Forrest plots revealed consistent HR of I<O for PFS and OS in each cohort.

Conclusions: The circadian biomarker indicator I<O is a robust, consistent and independent quantitative predictor of both PFS and OS in mCRC pts. Rest-activity rhythm monitoring deserves further testing for helping accurate determination of mCRC prognosis. The biological significance of I<O implies that specific treatments of circadian disruption could enhance survival in cancer pts.

Disruption of the circadian system by environmental factors: Effects of hypoxia, magnetic fields and general anesthetics agents

The biological clock of mammals is under the control of external factors, social life and the environment, and of internal genetic factors. When the biological clock of an individual is no longer in phase with its environment, either because there is no longer any harmony (desynchronization) between the two systems (shift work, night work, and transmeridian flights...) or because the perception of signals in the environment is defective (blindness) or because of a pathology, disorders of the biological clock occur resulting in persistent fatigue, sleep disorders leading to chronic insomnia and mood disturbances that can cause depression. We review here new groups of factors that have been recently studied and that can be considered as potential disruptors of the circadian time structure. These factors are hypoxia, magnetic fields and anesthetic agents whose importance has to be considered.

[Biological rhythms for anaesthesia and intensive care]

Knowledge of biological rhythms has led to better understanding of the time-of-day dependent effects of anaesthetic drugs. These chronopharmacological effects are currently explained by the biological rhythms modulating the pharmacokinetic, toxic and pharmacodynamic parameters of these substances. Such effect has been described for general anesthetics, local anaesthetics, analgesics as well as for antibiotics. But recent data also highlight that general anaesthetics, probably part of their brain effects, also alter the regulation of biological rhythms, including the sleep-wake or the endogenous circadian temperature rhythms. This desynchronization of biological rhythms can led to disturbance of the circadian secretion of many substances, including hormones. Finally, biological rhythms have been also described with regard to physiology of pain and cardiovascular physiopathology. The concept of biological rhythm should be present in mind not only for the clinical management of patients but also for setting studies in the field of anaesthesia, pain and intensive care.

Bcl-2 protects neuronal cells against taxol-induced apoptosis by inducing multi-nucleation

Taxol-induced peripheral neuropathy is a commonly-occurring side-effect in the treatment of cancer patients with taxoteres or taxanes. Taxol is known to induce apoptosis in a number of tumor cells. This report documents that, similar to proliferating cells, taxol induces apoptosis in NGF-differentiated PC12 cells, as assessed by exogenous FITC-annexin-V binding and nuclear fragmentation. It is shown that PC12 cells that stably overexpress Bcl-2 are protected against the toxic effect of taxol, as evidenced by the XTT assay and by a decreased fraction of propididum iodide positive cells in a dye exclusion test. Also the number of annexin-V-positive cells and the number of fragmented nuclei are lower in the Bcl-2 transfected cells. The effect is similar to the protective effect of Bcl-2 against NGF deprivation in differentiated PC12 cells. Although taxol forced both wild-type and Bcl-2-overexpressing cells into a mitotic state, only in Bcl-2-overexpressing cells did this lead to the appearance of metabolically active, multi-nucleated cells. This suggests that Bcl-2 is able to induce an alternative escape pathway, downstream of the G2/M block, in taxol-treated differentiated PC12 cells.

Bcl-2 protects against apoptosis-related microtubule alterations in neuronal cells

Bcl-2 is a gene with clear anti-apoptotic properties in neurodegenerative conditions. One of the earliest hallmarks of degeneration in neuronal cell cultures is the loss of neurite morphology. Therefore the effect of Bcl-2 on neuronal morphology and microtubule stability was studied in nerve growth factor differentiated PC12 cells. Microtubule dynamics were modulated using the microtubule stabilizer taxol and the microtubule destabilizer, okadaic acid, a protein phosphatase inhibitor. It was shown that Bcl-2 protects against both taxol- and okadaic acid induced neurite retraction. Bcl-2 overexpression also significantly reduced the increased ratio of acetylated tubulin over total tubulin induced by taxol treatment. Interestingly, Bcl-2 attenuates the decrease of the same ratio after exposure to okadaic acid, suggesting that Bcl-2 is able to normalize the level of acetylated tubulin. In addition, cell death and nuclear fragmentation, induced by okadaic acid, were reduced in Bcl-2 overexpressing cells. This protection is either downstream or independent of tau phosphorylation as quantitative immunocytochemistry with AT8 showed that Bcl-2 did not modify the level of tau phosphorylation. The data suggest that the protective effect of Bcl-2 on the neuronal cytoskeleton is probably linked to changes in the post-translational modification of tubulin.

Nimodipine and flunarizine have different effects on survival and morphology of PC12 cells during nerve growth factor deprivation

The purpose of this study was to examine the effect of antagonists of different subtypes of Ca(2+) channels (nimodipine and flunarizine) and two types of Ca(2+) chelating agents (the cell permeant Ca(2+) chelator 1,2-bis(2-aminophenoxy)ethane-N,N,N', N'-tetraacetic acid acetoxymethylester (BAPTA-AM) and the cell non-permeant Ca(2+) chelator EGTA) on neurite retraction and cell death of nerve growth factor (NGF)-differentiated PC12 cells after NGF deprivation. We demonstrated that flunarizine and nimodipine, but not BAPTA-AM and EGTA, provided protection against cell death due to NGF deprivation. Using time-lapse videomicroscopy and quantitative image analysis, we found that retraction of neurites was an early and fast phenomenon after removal of NGF. None of the compounds tested (flunarizine, nimodipine, BAPTA-AM, EGTA) could prevent the retraction of neurites.

A rapid method for the evaluation of compounds with mitochondria-protective properties

Mitochondrial dysfunction has been implicated in a number of neurodegenerative diseases, such as ischemia and Parkinson's disease. We present here a method that allows the rapid quantification of interventions, aimed at inhibiting the effect of mitochondrial membrane potential uncouplers, based on the ratioing properties of the fluorescent probe 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolcarbocyanine iodide (JC-1), by using currently available 96-well fluorescent plate readers. A method is presented for evaluation of cross-talk between the two excitation/emission channels. Further characterization of the probe shows that the effect of plasma membrane potential changes on JC-1 fluorescence ratio are negligible, but that the signal is very sensitive to pH. One of the most exciting applications is the possibility to perform end-point measurements, thanks to the ratioing properties of the probe. The system is tested in different culture types with different mitochondrial uncouplers. As an example of a quantitative evaluation, we show that flunarizine is able to inhibit, dose-dependently, FCCP mediated JC-1 signal increase. The procedure is simple and allows for the fast screening of mitochondria-protective compounds.

Bcl-2 protects against FCCP-induced apoptosis and mitochondrial membrane potential depolarization in PC12 cells

This report addresses the relation between Bcl-2 and mitochondrial membrane potential (DeltaPsi(m)) in apoptotic cell death. Rat pheochromocytoma (PC12) cells are differentiated into neuron-like cells with nerve growth factor (NGF). It is known that Bcl-2 can attenuate apoptosis induced by deprivation of neurotrophic factor. The protective effect of Bcl-2 has been correlated with preservation of DeltaPsi(m). Protonophores, such as carbonyl cyanide p-trifluoromethoxyphenylhydrazone (FCCP), collapse the proton gradient across the mitochondrial inner membrane, resulting in a complete abolition of the mitochondrial membrane potential. Based on the analysis of morphology, of phosphatidylserine exposure and of nuclear fragmentation we conclude that FCCP induces apoptosis in PC12 cells, which can be prevented by overexpression of Bcl-2. To determine whether the cytoprotective effect of Bcl-2 is due to stabilization of DeltaPsi(m), we investigated the effect of Bcl-2 on changes in DeltaPsi(m), induced by FCCP in PC12 cells. We showed that treatment with FCCP induced a reduction in DeltaPsi(m), as assessed with the lipophilic cationic membrane potential-sensitive dye JC-1, and that Bcl-2 protects against FCCP-induced changes in NGF differentiated PC12 cells. Our data indicate that Bcl-2 protects against FCCP-induced cell death by stabilizing DeltaPsi(m).

Chronic heart failure model induced by coronary embolization in sheep

OBJECTIVE

To create a model of chronic heart failure in a large animal.

METHODS

Heart failure was induced in sheep by single intracoronary injection of polymer macrobeads, which were administered into left main coronary artery (n=3) or selectively into left anterior descending (n=4) or left circumflex (n=5) coronary artery. The animals were followed by echocardigraphy for 20 weeks. Measurements comprised fractional area change (FAC), and diastolic ventricular area (EDVA) and regional wall-thickening fraction (WT%).

RESULTS

EDVA increased from 14.2+/-2.1 cm2 prior to embolization to 16.9+/-3.1 cm2 on day 1 (p<0.05), and remained significantly increased until completion of the follow-up period. FAC dropped from 47.9+/-4.6% at baseline to 29.3+/-4.4% on day 1 (p<0.001) and remained significantly depressed until 20 weeks later. In 9 selectively embolized animals WT% of the embolized area decreased from 33.8+/-8.0% at baseline to 5.3+/-2.6% on day 1 and remained significantly decreased.

CONCLUSIONS

A simple model of chronic heart failure was developed. It shows relatively high stability over time and may prove beneficial in experimental work on ventricular assist devices.

Okadaic acid-induced apoptosis in neuronal cells: evidence for an abortive mitotic attempt

There is increasing evidence that apoptosis in postmitotic neurons is associated with a frustrated attempt to reenter the mitotic cycle. Okadaic acid, a specific protein phosphatase inhibitor, is currently used in models of Alzheimer's research to increase the degree of phosphorylation of various proteins, such as the microtubule-associated protein tau. Okadaic acid induces programmed cell death in the human neuroblastoma cell lines TR14 and NT2-N, as evidenced by fragmentation of DNA and attenuation of this process by protein synthesis inhibitors. In differentiated TR14 cells, okadaic acid increases the fraction of cells in the S phase, induces the appearance of cyclin B1 and cyclin D1 markers of the cell cycle, and triggers a time-dependent increase in DNA fragmentation after release of a thymidine block. Fully differentiated NT2-N cells are forced to enter the mitotic cycle as shown by DNA staining. Chromatin condensation and chromosome formation are initiated, but the cells fail to complete their mitotic cycle. These data suggest that okadaic acid forces differentiated neuronal cells into the mitotic cycle. This pattern of cyclin up-regulation and cell cycle shift is compared with apoptosis induced by neurotrophic factor deprivation in differentiated rat pheochromocytoma PC12 cells.

Altered [Ca2+] homeostasis in PC12 cells after nerve growth factor deprivation

[Ca2+]i homeostasis in individual PC12 cells after elevated [K+]o was studied by ratiometric microscopy, during nerve growth factor (NGF) deprivation. A significantly lower number of cells responded with an increased [Ca2+]i in the NGF deprived condition. Moreover, the responding cells were more deficient in regulating their [Ca2+]i back to control levels, after the transient peak. This suggests that differentiated neurons do not traverse the apoptotic program homogeneously with regard to their [Ca2+]i regulation and that NGF deprived PC12 cells have more difficulties to reduce their [Ca2+]i after influx of [Ca2+]o.

Aberrant tau phosphorylation and neurite retraction during NGF deprivation in PC12 cells

Recently apoptotic markers have been found in Alzheimer's Disease (AD) brain. To investigate the relation between tau phosphorylation and apoptosis, immunocytochemistry of AT8 (indicating the degree of phosphorylation at the tau Ser202/Thr205 site) was quantitatively determined the degree of tau phosphorylation at the Ser202 site was monitored during neuronal apoptosis in differentiated PC12 cells after nerve growth factor (NGF) deprivation. During this programmed cell death a prominent retraction of neurites took place that was associated with a clear increase in the level of AT8 signalaberrant phosphorylated tau at the Ser202 site. The broad spectrum kinase inhibitor staurosporine attenuated both this increase in tau phosphorylation, neurite retraction, and apoptosis. We suggest that at some point during programmed cell death, kinases with tau as substrate become activated and that the resulting loss of cytoskeletal integrity leads to neurite instability.