Age-dependent reduction of the response of rat cardiac muscle to the phosphodiesterase inhibitor milrinone

This study aimed to investigate whether milrinone effect on cardiac muscle contractility undergoes to age-related changes. Experiments were carried out on papillary muscles isolated from right ventricle of Brown Norway rats belonging to two different age groups: 2 month old and 18 month old. The effect of milrinone (10-100 microM) on rat cardiac muscle in vitro preparations was characterized by a reduction of peak developed tension and of contraction duration. Furthermore, the recovery of contractility after a contractile cycle, i.e. the mechanical restitution was faster in the presence of milrinone than in control conditions. All these effects were reduced in preparations from 18 month old rats compared to preparations from 2 month old rats. The decrease of milrinone effect on the mechanical restitution was particularly pronounced. The reduction of the milrinone effects is likely connected with the reduction of the maximal effect of adrenergic stimulation, although the molecular basis of this link is not yet clearly understood

The Effects of thyroid Hormone Modulation on Rat Liver Injury Associated with Ischemia-Reperfusion and Cold Storage.

We investigated the effects of thyroid hormone modulation on liver injury associated with ischemia-reperfusion (I-R) and cold storage in rats. First, euthyroid and thyroxine (T-4)-pretreated rats were exposed in vivo to 20-min global liver ischemia, then 30-min reperfusion. Liver injury was assessed by measuring serum alanine aminotransferase (ALT) levels. Liver concentrations of adenine nucleotides, reduced glutathione (GSH), and oxidized glutathione were evaluated. Second, rats were given the antithyroid drug propylthiouracil (PTU). Livers stored at 0-1 degrees C in Euro-Collins' solution for 20 h were reperfused at 37 degrees C for 15 min. Lactate dehydrogenase (LDH) in the effluent perfusate and bile flow were evaluated during reperfusion. Serum ALT levels increased after ischemia and I-R. ALT increased significantly more in T-4-pretreated than in euthyroid rats after ischemia and I-R. Preischemic levels of adenosine triphosphate (ATP) were significantly lower in livers from T-4-pretreated than in euthyroid rats (6.22 +/- 0.7 and 11 +/- 0.9 nmol/mg protein, respectively; P < 0.05). After ischemia, Liver Am was similarly reduced in T-4-pretreated and euthyroid rats. After reperfusion, Am partially recovered in euthyroid rats but remained low in T-4-pretreated rats (6.7 +/- 1.0 and 1.91 +/- 0.7 nmol/mg protein, respectively; P < 0.05). Preischemic levels of liver GSH decreased to 44% in T-4-pretreated rats. After ischemia, GSH decreased similarly in euthyroid and T-4-pretreated rats. GSH recovered promptly after reperfusion in euthyroid rats but remained low in T-4-pretreated rats (13.9 +/- 3.3 and 3.9 +/- 0.9 nmol/mg protein, respectively; P < 0.02). During reperfusion after cold storage, LDH in effluent perfusate was significantly lower and bile flow higher in Livers from PTU-pretreated rats than from euthyroid rats. The histoyathological changes observed after I-R and cold storage confirmed the biochemical findings. Our results suggest that T-4 administration exacerbates pretransplant liver damage by increasing liver susceptibility to I-R, whereas PTU administration reduces the liver injury associated with cold storage. Implications: We studied the effects of thyroid hormone modulation on liver injury associated with ischemia-reperfusion and cold storage in rats. Thyroxine administration increased susceptibility to ischemia-reperfusion injury, whereas the antithyroid agent propylthiouracil reduced the deleterious effects associated with cold storage

TOWARDS AN INTEGRATED SYSTEM FOR THE MOBILITY OF SCI PEOPLE

A multi-disciplinary research project on Biomechanics is presented. This paper deals with the preliminary research on the design and realization of innovative cycling road devices which aim to improve both comfort and performance of spinal cord injured (SCI) athletes. The first step along the research path is devoted to the design of an instrumented handbike (HB) allowing to acquire or to estimate mechanical and physiological measurements in both indoor and outdoor performances. Recent studies describe the HB as a promising device which seems to be less straining and more efficient, with respect to wheelchair, not only as a training method but also as an early rehabilitation technique after an acute SCI. Nonetheless, few efforts have been put in addressing some safety and ergonomics issues that affect these vehicles. The final goal of the project is the design of a new concept human powered system for the mobility of disabled people (SCI persons in particular)