Neuroprotective strategies against calpain-mediated neurodegeneration.

Calpains are calcium-dependent proteolytic enzymes that have deleterious effects on neurons upon their pathological over-activation. According to the results of numerous studies to date, there is no doubt that abnormal calpain activation triggers activation and progression of apoptotic processes in neurodegeneration, leading to neuronal death. Thus, it is very crucial to unravel all the aspects of calpain-mediated neurodegeneration in order to protect neurons through eliminating or at least minimizing its lethal effects. Protecting neurons against calpain-activated apoptosis basically requires developing effective, reliable, and most importantly, therapeutically applicable approaches to succeed. From this aspect, the most significant studies focusing on preventing calpain-mediated neurodegeneration include blocking the N-methyl-d-aspartate (NMDA)-type glutamate receptor activities, which are closely related to calpain activation; directly inhibiting calpain itself via intrinsic or synthetic calpain inhibitors, or inhibiting its downstream processes; and utilizing the neuroprotectant steroid hormone estrogen and its receptors. In this review, the most remarkable neuroprotective strategies for calpain-mediated neurodegeneration are categorized and summarized with respect to their advantages and disadvantages over one another, in terms of their efficiency and applicability as a therapeutic regimen in the treatment of neurodegenerative diseases.

Irradiation doses on thyroid gland during the postoperative irradiation for breast cancer.

PURPOSE: Thyroid gland is one of the radiosensitive endocrine organs in the body. It has been shown that direct irradiation of thyroid with total doses of 26 to 30 Gy can lead to functional abnormalities. In this study, irradiation doses on thyroid gland of the patients who received postoperative chest-wall/breast and regional nodal irradiation were assessed. MATERIALS AND METHODS: Retrospective analyses of treatment plans from 122 breast cancer patients who were treated with 3D conformal radiotherapy (3D CRT) planning was performed. All patients received irradiation to supraclavicular/level III lymph nodes in addition to chest-wall/breast. A total dose of 46 Gy was delivered in 25 days to supraclavicular/level III lymph node region while a total dose of 50 Gy was delivered to whole breast/chest-wall. Thyroid gland was contoured on 2-5 mm thickness of computed tomography scans. Absolute thyroid volume, mean thyroid doses were calculated. RESULTS: The mean thyroid volume of all patients was 16.7 cc (min: 1.9 cc, max: 41.6 cc). The mean irradiation dose on was 22.5 Gy (0.32 Gy-46.5 Gy). The level of dose was higher than 26 Gy in 44% of the patients. CONCLUSIONS: In majority of the node-positive breast cancer patients treated with 3D CRT, the thyroid gland was exposed to considerable doses. On the other hand, for 44% of the patients are at risk for developing thyroid function abnormalities which should be considered during the routine follow-up.

Protein kinase C activation causes neurite retraction via cyclinD1 and p60-katanin increase in rat hippocampal neurons.

Neurons are differentiated postmitotic cells residing in G0 phase of the cell cycle and are unable to proceed through G1 phase, in which cyclinD1 needs to be up-regulated for initiation. Yet, a growing body of evidence has shown that cell cycle re-activation via cyclinD1 up-regulation drives neurons into apoptosis. By contrast, there is also evidence demonstrating cell cycle proteins playing roles in neuronal differentiation. cyclinD1 has been shown to be differently regulated by protein kinase C alpha (PKC-α) in various mitotic cells. Based on these different effects, we investigated the role of PKC-α on cyclinD1 regulation in hippocampal neurons. Neurons were treated with PKC activator, PMA, and analysed for subcellular distributions of PKC-α and cyclinD1. Remarkably, PMA treatment increased nuclear PKC-α and cyclinD1, but not PKC-ε in hippocampal neurons. Increases in nuclear PKC-α and cyclinD1 were accompanied by microtubule re-organisation via increases in tau and retinoblastoma protein phosphorylation levels. Increased p60-katanin and p53 changed the neuronal morphology into neurons with shorter, but increased number of side branches. Since up-regulation of cell cycle is associated with apoptosis in neurons, we also analysed changes in Bax, Bcl-2 early and PARP (poly(ADP-ribose)polymerase), caspase3 late apoptotic markers. However, we did not observe any indication of apoptosis. These data suggest that in addition to their previously known roles in mitotic cells on cell cycle regulation, PKC-α and cyclinD1 seem to be important for differentiation, and nuclear PKC-α and cyclinD1 interfere with differentiation by promoting microtubule re-organisation through PKC signaling without triggering apoptosis.

SpeedyRINGO inhibits calpain-directed apoptosis in neurons.

The calcium-activated proteolytic enzyme calpain is one of the key proteins that can directly or indirectly drive neurons into apoptosis. The indirect way is through cyclin dependent kinase 5 (CDK5), a non-mitotic kinase, which is upregulated through calpain overactivation and followed by a subsequent increase in p53 and active caspase-3 levels under neurodegenerative conditions. The direct way is the upregulation of p53 by calpain itself, since p53 is a substrate for it. SpeedyRINGO is an atypical cell cycle regulator that has been shown to have protective effects in mitotic cells against apoptosis by inhibiting caspase-3 activation when p53 is present. Our aim was to reveal possible protective effects of SpeedyRINGO against calpain-induced caspase-3 activation in neurons which is crucial in terms of providing novel insights in preventing the caspase-3 activation cascade in neurodegeneration. For this reason, mRNA and protein levels were analyzed by qRT-PCR, western blotting, and immunofluorescence. We show that calpain overactivation leads to the upregulation of p53 and a subsequent increase in active caspase-3 level, indicating activation of apoptotic machinery in neurons. This calpain-directed caspase-3 activation upon upregulation of p53 is inhibited by the expression of SpeedyRINGO in rat hippocampal neurons. Therefore, SpeedyRINGO acts as a savior for neurons that are under apoptosis due to caspase-3 activation.

Cell cycle markers have different expression and localization patterns in neuron-like PC12 cells and primary hippocampal neurons.

Neuron-like PC12 cells are extensively used in place of neurons in published studies. Aim of this paper has been to compare mRNA and protein expressions of cell cycle markers; cyclinA, B, D, E; Cdk1, 2 and 4; and p27 in post-mitotic primary hippocampal neurons, mitotically active PC12 cells and NGF-differentiated post-mitotic PC12 cells. Contrary to PC12 cells, in neurons, the presence of all these markers was detected only at mRNA level; except for cyclinA, cyclinE and Cdk4, which were detectable also at protein levels. In both NGF-treated PC12 cells and neurons, cyclinE was localized only in the nucleus. In NGF-treated PC12 cells cyclinD and Cdk4 were localized in the nucleus while, in neurons cyclinD expression was not detectable; Cdk4 was localized in the cytoplasm. In neurons, cyclinA was nuclear, whereas in NGF-treated PC12 cells, it was localized in the cell body and along the processes. These results suggest that PC12 cells and primary neurons are different in terms of cell cycle protein expressions and localizations. Thus, it may not be very appropriate to use these cells as neuronal model system in order to understand neuronal physiological activities, upstream of where may lie cell cycle activation triggered events.

Sonographic measurement of cervical length and risk of preterm delivery.

AIM: To study the relationship between cervical lengths measured by ultrasound and risk of preterm delivery. MATERIAL & METHODS: We examined 209 women with singleton pregnancies. The inclusion criteria were women who presented with regular and painful contractions (≥2 contractions at intervals of 10 min for at least 1 h). Transvaginal scan was performed to measure the cervical length. The clinical management of the women, including hospitalization and administration of tocolytics, was determined by the attending obstetricians, who were blinded about cervical length. The primary outcome was delivery within 7 days of presentation. RESULTS: Delivery within 7 days of presentation occurred in 19/209 (9%) of pregnancies who were presenting with regular and painful uterine contraction at 31 weeks of gestation, and this was inversely related to cervical length. Logistic regression analysis demonstrated that cervical length and history of abortion remain as significant contributors to predicting delivery within 7 days. Of the patients who presented with threatened preterm labor, 117 (56%) received tocolytics, and 92 (44%) did not. In the group with a cervical length of <15 mm, delivery within 7 days occurred in 15/21 (71.4%) who were treated with tocolytics and 2/5 (40%) that were managed expectantly. CONCLUSION: Women with threatened preterm labor and a cervical length of <15 mm at presentation are at high risk of delivering preterm within 7 days. Sonographic measurement of cervical length helps to avoid over-diagnosis of preterm labor.