Heat shock proteins. I : Classification and roles in pathological processes

in Annales de Médecine Vétérinaire (2002), 146(4), 201-216

All living systems have evolved mechanisms to maintain homeostasis in the face of rapid environmental changes. When exposed to elevated temperatures, most of the cells activate the synthesis of a specific ... [more ▼]

All living systems have evolved mechanisms to maintain homeostasis in the face of rapid environmental changes. When exposed to elevated temperatures, most of the cells activate the synthesis of a specific group of proteins called Heat Shock Proteins (Hsps). This heat shock response, under control of specific transcription factors, the Heat Shock factors (HSF), is an evolutionarily conserved mechanism, from bacteria to humans. Heat Shock Proteins are classified into families according to their molecular weight (Hsp 25, 40, 70, 90, 105). They play the role of molecular chaperones by binding and protecting other molecules (proteins, RNAs). The function of Hsp is to prevent accumulation of non-native proteins either by assisting proper folding of polypeptides or by driving them to proteosome pathway for degradation. Hsps are involved in various pathological processes that are accompanied by protein alterations such as chronic or degenerative diseases. This review describes structural and functional characteristics of the six main Hsps classes. It also focuses on their respective role in highly studied pathologies. The diversity of Hsps implications in these diseases explains that they became recently a strategic target in development of new therapeutic strategies. [less ▲]

Morphometric Study of the Equine Navicular Bone: Comparisons between Fore and Rear Limbs

in Zentralblatt für Veterinarmedizin. Reihe A (1997), 44(9-10), 579-94

Navicular bones collected from the four limbs of 95 sound horses were studied. The anatomic bases have been laid down about morphometry of the navicular bones and their variations according to limbs ... [more ▼]

Navicular bones collected from the four limbs of 95 sound horses were studied. The anatomic bases have been laid down about morphometry of the navicular bones and their variations according to limbs, after corrections have been made for morphologic type, gender, weight, size and age. All the dimensions of the navicular bone (except for the thickness) were larger in the fore limb. This phenomenon probably reflects an attempt to compensate for the greater forces exerted upon the fore limbs during exercise and at rest. Navicular bones collected from the four limbs of 61 sound horses were studied and the anatomic bases were described for histomorphometry of the fore and rear navicular bones. Fore navicular bones possess less cortical bone at the level of the articular surface, as well as at the level of the flexor surface and proximal border, but larger amounts of cancellous bone. Articular and flexor surface cortical bone show a larger porosity in the fore navicular bones and a larger amount of mineralized cartilage. The mineralized portion for distal impar- and collateral sesamoidean ligaments are also larger for the fore navicular bones. Two distinct zones are observed for the flexor surface cortex that have never been reported in the literature before: an external zone, which is mainly composed of poorly remodelled lamellar bone, arranged in a disto-proximal oblique direction, and an internal zone, which is mainly composed of secondary bone, with a latero-medial direction of Haversian canals. Bone architecture is discussed with regard to the mechanic load, encountered by the bone during locomotion. [less ▲]

Modulatory Effect of Neuropeptide Y on Acetylcholine-Induced Oedema and Vasoconstriction in Isolated Perfused Lungs of Rabbit

in British Journal of Pharmacology (1994), 113(3), 973-81

1. The modulatory role of neuropeptide Y (NPY) on pulmonary oedema induced by acetylcholine and capsaicin was investigated. The effects of NPY on the haemodynamic response to acetylcholine, phenylephrine ... [more ▼]

1. The modulatory role of neuropeptide Y (NPY) on pulmonary oedema induced by acetylcholine and capsaicin was investigated. The effects of NPY on the haemodynamic response to acetylcholine, phenylephrine and substance P were also investigated. 2. Isolated, ventilated, exsanguinated lungs of the rabbit were perfused with a constant flow of recirculating blood-free perfusate. The double/arterial/venous occlusion method was used to partition the total pressure gradient (delta Pt) into four components: the arterial gradient (delta Pa), the pre- and post-capillary gradients (respectively delta Pa' and delta Pv') and the venous pressure gradient (delta Pv). Endothelial permeability was evaluated by measuring the capillary filtration coefficient (Kf,c). 3. Acetylcholine (10(-8) M to 10(-4) M) and substance P (SP, 10(-10) M to 10(-6) M) induced a concentration-dependent increase in the Kf,c. Capsaicin (10(-4) M) and 5-hydroxytryptamine (5-HT) (10(-4) M) also increased this parameter. NPY (10(-8) M) completely inhibited the effects of acetylcholine and capsaicin on the Kf,c, without preventing the effects of substance P and 5-HT. 4. Acetylcholine induced concentration-dependent vasoconstriction in the precapillary segment. The effect was inhibited by NPY and aspirin, an inhibitor of cyclo-oxygenase, while ketanserin, a 5-HT2 receptor antagonist, and SR140333, a new NK1 antagonist, had no protective effect. Phenylephrine increased delta Pa at high concentration, an effect also inhibited by NPY and aspirin. Substance P had no significant haemodynamic effect. When injected together with NPY, substance P (10(-6) M) induced a significant increase in the total pressure gradient.(ABSTRACT TRUNCATED AT 250 WORDS) [less ▲]