Protein kinase C mRNA and protein expressions in hypobaric hypoxia-induced cardiac hypertrophy in rats.

AIM: Protein kinase C (PKC), cloned as a serine/threonine kinase, plays key roles in diverse intracellular signalling processes and in cardiovascular remodelling during pressure overload or volume overload. We looked for correlations between changes in PKC isoforms (levels and/or subcellular distributions) and cardiac remodelling during experimental hypobaric hypoxic environment (HHE)-induced pulmonary hypertension. METHODS: To study the PKC system in the heart during HHE, 148 male Wistar rats were housed for up to 21 days in a chamber at the equivalent of 5500 m altitude level (10% O(2)). RESULTS: At 14 or more days of exposure to HHE, pulmonary arterial pressure (PAP) was significantly increased. In the right ventricle (RV): (1) the expression of PKC-alpha protein in the cytosolic and membrane fractions was increased at 3-14 days and at 5-7 days of exposure respectively; (ii) the cytosolic expression of PKC-delta protein was increased at 1-5, 14 and 21 days of exposure; (3) the membrane expressions of the proteins were decreased at 14-21 (PKC-betaII), 14-21 (PKC-gamma), and 0.5-5 and 21 (PKC-epsilon) days of exposure; (4) the expression of the active form of PKC-alpha protein on the plasma membrane was increased at 3 days of exposure (based on semiquantitative analysis of the immunohistochemistry). In the left ventricle, the expressions of the PKC mRNAs, and of their cytosolic and membrane proteins, were almost unchanged. The above changes in PKC-alpha, which were strongly evident in the RV, occurred alongside the increase in PAP. CONCLUSION: PKC-alpha may help to modulate the right ventricular hypertrophy caused by pulmonary hypertension in HHE.

Non-contact determination of arterial blood pressure alterations induced by blood loss using laser irradiation on the common carotid artery.

In order to avoid the secondary exposure of medical personnel to toxic materials under biochemical hazard conditions, we have reported a method for non-contact monitoring of heart and respiratory rates, using microwave radar or laser irradiation. In large-scale disasters, it is important to be able to diagnose shock without touching patients. We evaluated a non-contact method of monitoring arterial blood pressure alterations of New Zealand rabbits induced by blood loss, using He-Ne laser reflection on the common carotid artery. PVR was significantly correlated with systolic blood pressure (r = 0.95, p < 0.01), where PV = peak voltage of reflected laser amplitude, and PVR = PV(present moment state)/PV(normal state). The following formula was derived using the least-squares linear fitting: SBP = 69.6 PVR + 8.2, in which SBP is the systolic blood pressure. Before blood withdrawal, the mean blood pressure, heart rate and haematocrit were 68 +/- 3 mmHg, 154 +/- 10 bpm and 40 +/- 2%, respectively. After intervention, the mean blood pressure, heart rate and haematocrit were 38 +/- 5 mmHg, 197 +/- 25 bpm and 30 +/- 2%, respectively. The proposed non-contact method appears promising for future clinical application in determining arterial blood pressure alterations. It is likely to be useful in reducing the risk of secondary exposure to toxic chemicals or infectious organisms in the case of large-scale disasters.

Osteopontin expression in normal and hypobaric hypoxia-exposed rats.

AIM: Experimental pulmonary hypertension induced in a hypobaric hypoxic environment (HHE) is characterized by structural remodelling of the heart and pulmonary arteries. Osteopontin (OPN) has emerged as a key factor in cardiovascular remodelling in response to pressure or volume overload. We studied the possible effects of HHE on the OPN synthesis system. METHODS: One hundred and forty-eight male Wistar rats were housed in a chamber with conditions equivalent of an altitude of 5500 m for up to 21 days. RESULTS: Plasma OPN protein level was found to be significantly decreased on day 0.5 of exposure to HHE, as was the level in the adrenal gland (which secreted highest levels of OPN protein). In the right ventricle of the heart (mRNA) and the lung (protein), OPN expression was found to be significantly increased only on day 1 and day 5, respectively, of exposure to HHE. By immunohistochemistry, the distribution and intensity of OPN protein in several organs were found to alter during exposure to HHE. However, these changes in OPN synthesis did not coincide with the moderate increase in pulmonary arterial pressure (PAP) (maximal mean PAP, 24.5 mmHg) during HHE. CONCLUSION: Pulmonary hypertension in HHE with conditions equivalent of an altitude of 5500 m may induce little or no OPN in heart and lung. Sustained induction may require a more severe PAP overload.

Biomimetic apatite formation on polyethylene photografted with vinyltrimethoxysilane and hydrolyzed.

A photografting technique to produce functional groups of silanol able to induce apatite nucleation was attempted on polyethylene substrate for biomimetic formation of bone-mineral-like apatite layer on its surface. The polyethylene surface was subjected to vapor-phase photografting of vinyltrimethoxysilane and subsequently to hydrolysis. The photografting formed methoxysilyl groups on the polyethylene substrate, which was changed into silanol groups successively by the hydrolysis in a hydrochloric solution. The polyethylene modified in this way formed a dense and homogeneous bone-mineral-like apatite layer in a solution with ion concentrations 1.5 times that of human blood plasma. This result indicates that the biomimetic process in combination with a polymeric grafting technique might provide a homogeneous bone-mineral-like apatite coating even on polymer fibers to be woven into an apatite-polymer composite with three-dimensional structure analogous to that of natural bone.