Changes of Cytosolic Ca2+ under Metabolic Inhibition in Isolated Rat Ventricular Myocytes

To characterize cytosolic Ca2+ fluctuations under metabolic inhibition, rat ventricular myocytes were exposed to 200microM 2, 4-dinitrophenol (DNP), and mitochondrial Ca2+, mitochondrial membrane potential (delta psi m), and cytosolic Ca2+ were measured, using Rhod-2 AM, TMRE, and Fluo-4 AM fluorescent dyes, respectively, by Laser Scanning Confocal Microscopy (LSCM). Furthermore, the role of sarcolemmal Na+/Ca2+ exchange (NCX) in cytosolic Ca2+ efflux was studied in KB-R7943 and Na+-free normal Tyrode's solution (143 mM LiCl ). When DNP was applied to cells loaded with Fluo-4 AM, Fluo-4 AM fluorescence intensity initially increased by 70+/-10% within 70+/-10 s, and later by 400+/-200% at 850+/-46 s. Fluorescence intensity of both Rhod-2 AM and TMRE were initially decreased by DNP, coincident with the initial increase of Fluo-4 AM fluorescence intensity. When sarcoplasmic reticulum (SR) Ca2+ was depleted by 1microM thapsigargin plus 10microM ryanodine, the initial increase of Fluo-4 AM fluorescence intensity was unaffected, however, the subsequent progressive increase was abolished. KB-R7943 delayed both the first and the second phases of cytosolic Ca2+ overload, while Na+-free solution accelerated the second. The above results suggest that: 1) the initial rise in cytosolic Ca2+ under DNP results from mitochondrial depolarization; 2) the secondary increase is caused by progressive Ca2+ release from SR; 3) NCX plays an important role in transient cytosolic Ca2+ shifts under metabolic inhibition with DNP.

Differential Activation of Ras/Raf/MAPK Pathway between Heart and Cerebral Artery in Isoproterenol-induced Cardiac Hypertrophy

Cardiac hypertrophy contributes an increased risk to major cerebrovascular events. However, the molecular mechanisms underlying cerebrovascular dysfunction during cardiac hypertrophy have not yet been characterized. In the present study, we examined the molecular mechanism of isoproterenol (ISO) -evoked activation of Ras/Raf/MAPK pathways as well as PKA activity in cerebral artery of rabbits, and we also studied whether the activations of these signaling pathways were altered in cerebral artery, during ISO-induced cardiac hypertrophy compared to heart itself. The results show that the mRNA level of c-fos (not c-jun and c-myc) in heart and these genes in cerebral artery were considerably increased during cardiac hypertrophy. These results that the PKA activity and activations of Ras/Raf/ERK cascade as well as c-fos expression in rabbit heart during cardiac hypertrophy were consistent with previous reports. Interestingly, however, we also showed a novel finding that the decreased PKA activity might have differential effects on Ras and Raf expression in cerebral artery during cardiac hypertrophy. In conclusion, there are differences in molecular mechanisms between heart and cerebral artery during cardiac hypertrophy when stimulated with beta2 adrenoreceptor (AR), suggesting a possible mechanism underlying cerebrovascular dysfunction during cardiac hypertrophy.

Immunopathological study of apoptotic related factors in oral squamous cell carcinoma

Oral squamous cell carcinoma [OSCC] is considered the sixth most common malignancy , and a major cause of cancer morbidity and mortality world wide. One of the capabilities required for carcinogensis is evasion of apoptosis .This involves normal alteration in the Fas [Apo-1/ CD95] receptor ligand apoptotic pathway . Apoptosis is a physiological cell death , it plays a significant role in the pathogenesis of various diseases and tumors and also plays the main role in killing of cancer cells by chemo and radiotherapy. Twenty two cases of OSCC were studied in this research for the expression of both antigens Fas and Fas-L ligand .The correlation of their expression with the histopathological grading and with the immune escape behavior of the OSCC was the aim of this work. The correlation between the pattern of expression of Fas and the three histopathological grades of OSCC was highly significant [p< 0.004]. The apoptotic Fas receptor showed downregulation as we move to the high grade of OSCC. This results point out that it is one the of hallmark of immune escape behavior of OSCC. The altered expression of Fas antigen can be used as a marker for dys-plastic and premalignant changes. It is a prognostic factor for tumor aggressive behavior and as a predictor factor for response to chemo or radiotherapy. Primary tumors negative for the Fas-L is one of the immune escape policies of OSCC since its presence only attacks neutrophils Fas -L tumor cell expression is a late step in tumor progression and is mostly demonstrated in metastatic cases