Second messengers in the nucleus

Sposobnost stanice da odgovori na vanjski podražaj uključuje prijenos poruke kroz staničnu membranu i njeno prevođenje u unutrašnji signal, druge glasnike, koji kontroliraju mnoge stanične procese, kao što su rast stanice, diferencijaciju i proliferaciju. Važnu ulogu u prijenosu poruke imaju fosfoinozitidi, mali membranski lipidi, čijom razgradnjom uz pomoć fosfolipaze C, nastaju drugi glasnici: inozitol- (1,4,5)-trifosfat, inositol-(l,3,4,5)-tetrafosfat i sn-1,2-diacilglicerol. Inozitol-( 1,4,5)-trifosfat oslobađa se u citoplazmu u kojoj zajedno sa svojim fosforiliranim oblikom, inositol-(l,3,4,5)-tetrafosfatom, mobilizira kalcij iz unutarstaničnih rezervoara, dok sn-1,2-diacilglicerol aktivira protein kinazu C. Nedavne studije su sugerirale postojanje zasebnog signalnog sustava u jezgrama, budući da su u njima nađene gotovo sve komponente dobro proučenog signalnog sustava stanične membrane, kontroliranoga preko površinskih receptora. Zasad još ostaje da se razjasni da li je jezgrin signalni sustav dio općeg signalnog sustava započetog na staničnoj membrani, ili je on zaseban i neovisan o njemu?The ability of cells to respond to external stimuli involves the transduction of messages across the plasma membrane and their translation into internal signal, second messengers, which control many cell processes such as cell growth, differentiation and proliferation. A prominent role in message transduction is played by phosphoinositides, minor membrane lipids, whose breakdown through phospholipase C produces the second messengers: inositol-(l,4,5)- trisphosphate, inositol-( 1,3,4,5)-tetraphosphate and sn-l,2-diacylglycerol. Inositol (l,4,5)-trisphosphate and Ins(l,3,4,5)P-tetrakisphosphate, released into the cytoplasm, mobilize calcium from internal stores, whereas sn-l,2 diacylglycerol activates protein kinase C. Recent studies suggested the existence of a discrete signal system in the nuclei. It includes all components of well-known plasma membrane-located system, which is under regulatory control by cell surface-located receptors. It remains to be clarified whether the nuclei signal system is a part of the general signal system originating at plasma membrane, or whether it is independent of it

Prognostic Value of Venoarterial Carbon Dioxide Gradient in Patients with Severe Sepsis and Septic Shock

Aim To investigate the changes in the venoarterial carbondioxide gradient (V-a Pco2) and its prognostic value for survival of patients with severe sepsis and septic shock. Methods The study was conducted in General Hospital Holy Spirit from January 2004 to December 2007 and included 71 conveniently sampled adult patients (25 women and 46 men), who fulfilled the severe sepsis and septic shock criteria and were followed for a median of 8 days (interquartile range, 12 days). The patients were divided in two groups depending on whether or not they had been mechanically ventilated. Both groups of patients underwent interventions with an aim to achieve hemodynamic stability. Mechanical ventilation was applied in respiratory failure. Venoarterial carbon dioxide gradient was calculated from the difference between the partial pressure of arterial CO2 and the partial pressure of mixed venous CO2, which was measured with a pulmonary arterial Swan-Ganz catheter. The data were analyzed using Kaplan-Meier survival analysis, along with a calculation of the hazard ratios. Results There was a significant difference between nonventilated and ventilated patients, with almost 4-fold greater hazard ratio for lethal outcome in ventilated patients (3.85; 95% confidence interval, 1.64-9.03). Furthermore, the pattern of changes of many other variables was also different in these two groups (carbon dioxide-related variables, variables related to acid-base status, mean arterial pressure, systemic vascular resistance, lactate, body mass index, Acute Physiology and Chronic Health Evaluation II, Simplified Acute Physiology II Score, and Sepsis-related Organ Failure Assessment score). Pco2 values (with a cut-off of 0.8 kPa) were a significant predictor of lethal outcome in non-ventilated patients (P = 0.015) but not in ventilated ones (P = 0.270). Conclusion V-a Pco2 was a significant predictor of fatal outcome only in the non-ventilated group of patients. Ventilated patients are more likely to be admitted with a less favorable clinical status, and other variables seem to have a more important role in their outcome

Incidence of Dentinal Micro Cracks during Root Canal Preparation with Self Adjusting File, Reciproc Blue, and ProTaper Next

Introduction: Forces formed during root canal instrumentation could cause the crack formation in dentinal walls. Their propagation may result in vertical root fracture and eventually tooth loss. The aim of the study was to explore microcrack formation after root canal preparation with Self-adjusting File (SAF), Reciproc Blue (RB), and ProTaper Next (PTN) instruments on young premolars by means of micro-computed tomography. Methods and Materials: Forty-five upper premolars with two canals, were extracted due to orthodontic reasons from patients aged 16 to 20 years and stored for up to two months. The teeth were scanned with a micro-CT (Nikon XT H 225, Tring, UK) at structural resolution of 20.2 µm and randomly divided into three groups: SAF, RB, and PTN. Specimens were instrumented and irrigation was performed with 12 mL of 2.5% sodium hypochlorite (NaOCl) and 4 mL of 17% ethylenediaminetetraacetic acid (EDTA) per root canal. Subsequently, the specimens were scanned under the same conditions as before, in wet condition and 24 h after drying. The presence of microcracks in dentinal walls was evaluated using the image-processing software Volume Graphics VGStudio Max 3. Results: No dentinal defect was found in any evaluated specimen, neither in pre-nor post-operative scans in wet and dry condition. Conclusion: Under the circumstances of this in vitro study instruments with improved design and metallurgy do not cause dentinal microcracks in young premolar teeth.Keywords: Dentin; Micro-computed Tomography; Nickel-titanium; Root Canal Preparatio

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