THE ADVANTAGES of using the rat for stroke study include the similarity of its intracranial circulation to that of man, 1 the abundant neurochemical data derived from rat brain, 2 and the relatively low animal cost which is important for large scale studies for statistical analysis. The several models of cerebral ischemia developed in the rat*" 13 can be classed by topography as global or focal and by chronology into reversible and irreversible. These methods entail intravascular embolization or exfravascular ligation. "16 For studies of the molecular events in cerebral ischemia, an animal model of focal and irreversible ischemia allowing only partial reperfusion to create a reproducible infarction of predictable size and location would be of considerable value. Intravascular embolization can cause focal irreversible ischemia without need for craniectomy but precise control of the ultimate site of the emboli is impossible and the infarction produced is usually multifocal and variable in size and location. 14 " 16 The extensive intracranial collateral circulation in the rat provided by the Circle of Willis, leptomeningeal anastomoses and dorsal collateral junctions 17 constrains the use of either unilateral or bilateral common carotid artery (CCA) ligation to produce consistent ischemic lesions unless a systemic insult such as hypoxia hypotension 6 is added. The additional systemic variable may cause generalized metabolic derangement and/or compromise cardiopulmonary function.The procedure of Tamura et al 9 of ligation of the proximal middle cerebral artery (MCA) through a subtemporal approach has been reported to result in consistent ischemic changes, but the procedure is technically difficult and sufficiently invasive that the survival of hours limits it to acute experiments.10 Coyle used a less invasive surgical approach with MCA ligation above the rhinal fissure but did not produce cerebral infarction in young Wistar rats. 11 We have undertaken to develop a reliable infarction model reasoning that the collateral circulation to the MCA territory is decisive in infarct occurrence after MCA ligation and that graded interruption of this collateral circulation would determine the lesion size in the bed of the occluded MCA. A systematic approach employing a relatively non-invasive surgical procedure has resulted in the development of a predictable large cortical infarct. Materials and Methods Laser Doppler FlowmetryTo determine that the blood flow in the right MCA territory after right MCA ligation was further reduced by occlusion of CCAs, we first measured the cerebral blood flow in the cortex supplied by the right MCA with a laser Doppler flowmeter

Our results show a high prevalence of chronic venous disorders of the lower limbs in the general population of France, with no significant geographic variations. They also provide interesting insights regarding the association of varicose veins, skin trophic changes, and venous symptoms.

The prevalence of scleroderma-type capillary abnormalities, as observed by in vivo microscopy, was determined in 173 patients from three rheumatic disease centers. The patients had a variety of connective tissue diseases: scleroderma (systemic sclerosis) 50; systemic lupus erythematosus 60, mixed connective tissue disease 26; Raynaud's disease 11; other rheumatic disorders 26. Enlarged and deformed capillary loops surrounded by relatively avascular areas, most prominently in the nailfolds, were found in 82% of patients with scleroderma and in 54% with mixed connective tissue disease. The rarity of these abnormalities in systemic lupus erythematosus (2%) despite the presence of Raynaud's phenomenon suggests that they are not an expression of the Raynaud's phenomenon frequently associated with scleroderma and mixed connective tissue disease. The single patient with Raynaud's disease and sclerodermatype capillary changes subsequently developed scleroderma.

The fingers of 75 patients with connective tissue disorders were examined by "wide-field" capillary microscopy. Four diagnostic groups were included in this study: rheumatoid arthritis-28, scleroderma-22, dermatomyositis-8, and systemic lupus erythematosus-17. On the basis of different patterns of elementary microvascular abnormalities and their distribution, 3 distinct groups were recognized among these patients: 1) increased visibility of nailfold subpapillary plexus in rheumatoid arthritis, 2) massive capillary dilatation in scleroderma-dermatomyositis, and 3) focal loss of capillaries and prominence of subpapillary vessels with "punched-out" lesions in systemic lupus erythematosus.