Thyroid hormone and cardioprotection: Study of p38 MAPK and JNKs during ischaemia and at reperfusion in isolated rat heart

It has been recently shown that long-term thyroxine administration increases the tolerance of the heart to ischaemia. The present study investigated whether thyroxine induced cardioprotection involves alterations in the pattern of p38 mitogen activated protein kinase (p38MAPK) and c-Jun NH₂-terminal kinases (JNKs) activation during ischaemia-reperfusion. L-thyroxine (T4) was administered in Wistar rats (25 g/100 g/day, subcutaneously) for 2 weeks (THYR), while normal animals served as controls (NORM). NORM and THYR isolated rat hearts were perfused in Langendorff mode and subjected to 10 or 20 min of zero-flow global ischaemia only and also to 20 min of ischaemia followed by 10, 20 or 45 min of reperfusion. Postischaemic recovery of left ventricular developed pressure at 45 min of reperfusion was expressed as % of the initial value. Activation of p38 MAPK and JNKs was assessed at the different times of the experimental setting by standard Western blotting techniques using a dual phospho p38MAPK and phospho JNKs (p46/p54) antibodies. Activation of p38 MAPK was significantly attenuated during ischaemia and reperfusion in thyroxine treated hearts compared to normal hearts. JNKs were found to be activated only during the reperfusion period. The levels of phospho JNKs were found to be lower in thyroxine treated hearts as compared to untreated hearts, though not at a statistically significant level. Postischaemic functional recovery was higher in THYR as compared to NORM, p < 0.05. In summary, in hearts pretreated with thyroxine, p38 MAPK was attenuated during ischaemia and at reperfusion and this was associated with improved postischaemic recovery of function.     

Protocol of a prospective study on the diagnostic value of transcranial duplex scanning of the substantia nigra in patients with parkinsonian symptoms

Background  

Parkinson's disease (PD) is the second most common neurodegenerative disorder. As there is no definitive diagnostic test, its diagnosis is based on clinical criteria. Recently transcranial duplex scanning (TCD) of the substantia nigra in the brainstem has been proposed as an instrument to diagnose PD. We and others have found that TCD scanning of substantia nigra duplex is a relatively accurate diagnostic instrument in patients with parkinsonian symptoms. However, all studies on TCD so far have involved well-defined, later-stage PD patients, which will obviously lead to an overestimate of the diagnostic accuracy of TCD.     

The conduction of protons in different stereoisomers of dioxolane-linked gramicidin A channels

Two different stereoisomers of the dioxolane-linked gramicidin A (gA) channels were individually synthesized (the SS and RR dimers;. Science. 244:813-817). The structural differences between these dimers arise from different chiralities within the dioxolane linker. The SS dimer mimics the helicity and the inter- and intramolecular hydrogen bonding of the monomer-monomer association of gA's. In contrast, there is a significant disruption of the helicity and hydrogen bonding pattern of the ion channel in the RR dimer. Single ion channels formed by the SS and RR dimers in planar lipid bilayers have different proton transport properties. The lipid environment in which the different dimers are reconstituted also has significant effects on single-channel proton conductance (g(H)). g(H) in the SS dimer is about 2-4 times as large as in the RR. In phospholipid bilayers with 1 M [H(+)](bulk), the current-voltage (I-V) relationship of the SS dimer is sublinear. Under identical experimental conditions, the I-V plot of the RR dimer is supralinear (S-shaped). In glycerylmonooleate bilayers with 1 M [H(+)](bulk), both the SS and RR dimers have a supralinear I-V plot. Consistent with results previously published (. Biophys. J. 73:2489-2502), the SS dimer is stable in lipid bilayers and has fast closures. In contrast, the open state of the RR channel has closed states that can last a few seconds, and the channel eventually inactivates into a closed state in either phospholipid or glycerylmonooleate bilayers. It is concluded that the water dynamics inside the pore as related to proton wire transfer is significantly different in the RR and SS dimers. Different physical mechanisms that could account for this hypothesis are discussed. The gating of the synthetic gA dimers seems to depend on the conformation of the dioxolane link between gA's. The experimental results provide an important framework for a detailed investigation at the atomic level of proton conduction in different and relatively simple ion channel structures.     

Partial edentulism and removable partial denture design in a dental school population: a survey in Greece

Gerodontology 2011; doi: 10.1111/j.1741‐2358.2010.00382.x Partial edentulism and removable partial denture design in a dental school population: a survey in Greece Objectives: To investigate the pattern of partial edentulism and the most frequent designs of cobalt‐chromium removable partial dentures (RPDs), constructed at the Dental School of Athens, Greece. Methods and materials: Five hundred and fifty‐three patients, between 42 and 81 years old, mostly males, treated by undergraduate dental students, were included. The survey was based on visual evaluation of master casts and work authorisation to dental technicians. Aspects examined were: Kennedy Classification, modification areas, major connectors, clasping, placement of rest seats and indirect retention. Results: Kennedy Class I was the most common encountered in the maxilla (50.5%) and in the mandible (70%). The most frequent major connectors were the lingual bar (92.6%) and the U‐shaped palatal strap (54%). The most common clasp was the Roach (69.2%) in Class I and Class II. In Class III and IV, the most common was the occlusally approaching clasp (55% and 70%). The most frequent location of the rest was mesial of abutment teeth. On the average, 39.5% of Class I RPDs and 58.6% of Class II RPDs had indirect retainers. Conclusion: A combination of the two major philosophies of RPD design (biomechanical and hygienic) was evident in the RPDs examined in our study.