Precision and accuracy of the new XPrecia Stride mobile coagulometer.

INTRODUCTION: Oral anticoagulation therapy (OAT) with coumarins (vitamin K antagonist) is the most used against thromboembolism. Prothrombin time (PT) International Normalized Ratio (INR) monitoring is fundamental to establish coumarins dosage and prevent bleeding complications or thrombotic events. In this contest, the method and apparatus used for providing the INR measurements are crucial. Several studies have been published regarding the precision and accuracy of mobile coagulometers with different conclusions. No studies have been published regarding the new XPrecia Stride Mobile Coagulometer (Siemens). The aim of this work is to analyze precision and accuracy of the new XPrecia Stride mobile coagulometer to provide recommendations for clinical use and quality control. MATERIALS AND METHODS: A total of 163 patients (mean age=77.4years old) under Warfarin OAT for whom the INR was assessed by both the traditional cs 2100i Sysmex and the new Xprecia Stride Mobile Coagulometer were included in this pilot study. RESULTS AND CONCLUSIONS: The precision of the new mobile coagulometer resulted very good (CV<3%). The analytical accuracy was also within the acceptable ranges of reliability (Lin's concordance=0.962). Finally, the clinical accuracy was also acceptable (deviation>15% from the true value in 20% of cases). Considering the overall results obtained by the new Xprecia Stride in comparison to that ones obtained from the other commercial devices, we can conclude that the new coagulometer is enough reliable for clinical settings. However, a larger trial to confirm these data is needed.

Platelet as a physiological model to investigate apoptotic mechanisms in Alzheimer beta-amyloid peptide production.

Although neuronal apoptosis in Alzheimer's disease is generally interpreted as the consequence of the toxicity of extracellular beta-amyloid (Abeta) peptide aggregates, some experimental results provide evidence that the Abeta overproduction can be the result of a primary neuronal degeneration. As platelets are considered a good model where to study proteolytic processing of the amyloid precursor protein (APP), we exposed platelets to the proapoptotic agent ionomycin and analyzed Abeta40 and Abeta42 levels in the intracellular and extracellular compartments. The activation of apoptotic pathways in platelets has been verified by mitochondrial membrane depolarization, exposure of phosphatidylserine, protease activation and morphological changes. A significative increase in intraplatelet Abeta40, but not Abeta42, was observed after 10 min treatment with ionomycin. Thus, the activation of apoptotic pathways in platelets determines an altered processing of APP leading to elevated levels of intracellular Abeta40. The specific intracellular production of Abeta40 represents a potential threat to the cells since very high local Abeta40 concentration increases the risk of its aggregation and toxicity. As a result, Abeta40 might be dangerous even before it becomes secreted rendering neurons highly vulnerable.

Interrelationship among neutrophil efficiency, inflammation, antioxidant activity and zinc pool in very old age.

Neutrophils are the first barrier against infections. Aged neutrophils display impaired oxidative burst and phagocytosis with subsequent less capability to destroy bacteria. In successful ageing (nonagenarians), neutrophil efficiency (phagocytosis) increases. After ingested microbes, aged neutrophils are less prone to undergo apoptosis favouring chronic inflammation. Moreover, the superoxide dismutase (SOD) activity, which is necessary in avoiding ROS produced by oxidative burst, is limited in ageing. The mechanisms of age-related changes in neutrophil function are not fully understood, taking also into account that nonagenarians escape infections in comparison with elderly. Zinc pool may be involved because it is pivotal for neutrophil efficiency and SOD activity. Since zinc also controls the inflammation, via IL-6 and soluble factor of gp130 (sgp130), we have assessed the possible interrelationship among oxidative burst, apoptosis, inflammation, SOD, adhesion molecule Mac-1 and zinc pool in elderly and in nonagenarians. The oxidative burst and the capacity to increase Mac-1 after PMA stimulation decrease both in elderly and nonagenarians, but the latter display a slight increased neutrophil induced apoptosis, decreased sgp130, increased SOD, and more neutrophil zinc content, as it occurs in young-adults. Significant correlation exists between sgp130 and zinc pool in very old age. These findings suggest lower chronic inflammation in nonagenarians, via more zinc available, with subsequent long-life survival. Therefore, a more correct interrelationship among neutrophil efficiency, inflammation, antioxidant activity and zinc pool exists in successful ageing with subsequent more effectiveness to control the inflammatory response to pathogens.

Melatonin provokes cell death in human B-lymphoma cells by mitochondrial-dependent apoptotic pathway activation.

Apoptosis is an important cell suicide programme involved in physiological and pathological processes. Apoptosis can be induced in different ways depending on cell type and acquired signal. Melatonin, the major secretory product of the pineal gland, participates in many important physiological functions and displays a remarkable functional versatility exhibiting antioxidant, oncostatic, anti-aging, and immunomodulatory properties. Recently, it has been shown that, in addition to pineal gland, human lymphoid cells are an important physiological source of melatonin and that may be involved in the regulation of the immune system. In this work, we examine the effect of melatonin on RAMOS-1 human leukaemic cells. Cell growth and viability, DNA fragmentation and JC-1, and annexin V expression have been determined. To elucidate the mechanism of action of melatonin, Western blot analyses for Bcl-2 and caspase-3 expression, and cytochrome c release were carried out. The results suggest that the apoptotic effect of melatonin is associated with cell-cycle arrest, downregulation of Bcl-2, mitochondrial membrane depolarization, cytochrome c release and activation of caspase-3. The intrinsic (mitochondrial dependent) pathway of caspase activation is the 'point of no return' commitment to cell death. Taken together, our study indicates that melatonin may play a role as potential therapeutic drug in specific lymphoproliferative diseases.

Pineal graft in old rats improves erythrocyte resistance to peroxyl radical-induced hemolysis.

Pineal graft from young to old rats was performed and red blood cell hemolysis, induced by the water-soluble radical initiator 2,2'-azobis (2-amidino-propane) dihydrochloride (AAPH), was evaluated 6 months after graft. Pineal graft modified the hemolysis curve kinetic profile in grafted rats versus age-matched controls, the 50% hemolysis time as well as the lag time were longer, whereas the maximal amount of hemolysis was lower, and it occurred over a longer period of time. Thiobarbituric acid reactive substances production was lower in pineal-grafted rats than in controls and the age-related decrease of erythrocyte membrane fluidity was prevented by pineal graft. The present findings support an important physiological role of pineal gland in preventing age-related alterations of erythrocyte membranes and suggest a possible antioxidant action of melatonin.

Effect of dietary restriction on DNA synthesis in vitamin E-deficient rats.

To assess the effect of dietary restriction on increased oxidative stress conditions, we measured the proliferative response of spleen lymphocytes from the following groups of adult rats: (1) control fed ad libitum (14 months of age); (2) vitamin E-deficient (12 months of age); and (3) vitamin E-deficient maintained on dietary restricted paradigm, that is, every other day schedule (12 months of age) animals. No significant change was observed among the three groups investigated at 24 h. At 48 h, [(3)H]thymidine incorporation was significantly lower in vitamin E-deficient rats vs. the other groups at Con A concentrations of 1 and 5 mug/mL, while at Con A concentration of 10 mug/mL the incorporation of the labeled compound in lymphocytes was significantly lower than only the vitamin E-deficient rats vs. controls. At 72 h: nonstimulated lymphocytes from ad libitum fed control rats showed significant higher values of [(3)H]thymidine incorporation vs. the other groups; no significant difference was found among the three groups investigated at 1 and 10 mug/mL Con A concentrations, while at 5 mug/mL Con A concentration, the lymphocytes from vitamin E-deficient rats showed a significant lower value of [(3)H]thymidine incorporation vs. the other groups. These data support that vitamin E-deficiency impairs the proliferative response of spleen lymphocytes from adult rats, while dietary restriction appears to be able to reverse this alteration. Although the mechanism(s) of action of dietary restriction in prolonging the life span and ameliorating health conditions are not know, it is currently supported that a reduced food intake results in a better control of free radical attacks to biological molecules as well as to several cellular and system functions. With specific reference to the present findings, dietary restriction may help the mitotic process dynamics to be accomplished in a condition of low rate of free radical damage, thus representing a physiological intervention capable of modulating positively the proliferative capacity of spleen lymphocytes and, in turn, the immune system, even in adverse conditions such as increased oxidative stress.

Apoptosis in human aortic endothelial cells induced by hyperglycemic condition involves mitochondrial depolarization and is prevented by N-acetyl-L-cysteine.

We investigated whether the dissipation of mitochondrial transmembrane potential (Delta(Psi)(m)) was involved in apoptosis of cultured human aortic endothelial cells (HAECs) exposed to hyperglycemic conditions (30 mmol/L glucose). In parallel experiments, N-acetyl-L-cysteine (NAC) was added to the culture medium to verify whether this antioxidant may prevent apoptosis in these cells. The binding of annexin V and DNA fragmentation were measured, in addition to the production of reactive oxygen species (ROS), the number of cells with depolarized mitochondria, and the intracellular glutathione (GSH) content. As compared to the control (5 mmol/L glucose), high-glucose treatment increases both ROS generation and the number of cells binding annexin V. Moreover, a simultaneous decrease of intracellular GSH content was observed, which was accompanied by an increased number of cells showing both depolarized mitochondria and fragmented DNA. Incubation of HAECs with high glucose in the presence of 10 mmol/L NAC prevented the drop of intracellular GSH content, and decreased both ROS generation and the number of cells committed to apoptosis. These results suggest that high glucose triggers the same cascade of molecular events as do other apoptosis inducers in other cells. Among these events, the disruption of mitochondrial membrane barrier function might be decisive because it causes the release of soluble proteins from intermembrane space, which then induce nuclear apoptotic changes.