The morphological and biochemical changes in skeletal muscle fibers by dietary protein restriction.

The effects of dietary protein restriction on skeletal muscle fibers were studied according to morphological and biochemical approaches. Protein and DNA content of quadriceps muscles from young adult rats were decreased by the low protein and protein-free diet. Morphological examination demonstrated that there was a significant decrease in the size of muscle fibers without change in their numbers due to protein restriction. The protein/DNA ratio, accepted as an index of cell size in biochemical approaches, was compared with cell size on photomicrographs. Actual fiber size appeared much smaller than that indicated by the protein/DNA ratio.     

Prevention of postoperative paraplegia during thoracoabdominal aortic surgery

BACKGROUND: We present data showing the impact of sequential multisegmental aortic clamping accompanied by reimplantation of as many segmental arteries as possible on the prevention of postoperative paraplegia or paraparesis during thoracoabdominal aortic graft replacement. METHODS: Since 1987 we have performed graft replacements in 51 individuals undergoing thoracoabdominal aortic surgery using the technique of normothermic partial bypass with sequential multisegmental aortic clamping. The procedure was performed emergently in 10 patients and electively in 41 patients. The patients ranged in age from 22 to 82 years (mean, 57.6 +/- 13.8 years). Indications for surgery included dissecting thoracoabdominal aortic aneurysm (n = 19) and nondissecting thoracoabdominal aortic aneurysm (n = 32). The extent of aneurysm was Crawford type I in 19 patients, type II in 7 patients, type III in 12 patients, and type IV in 13 patients. Along the entire extent of aneurysm to be replaced, we reimplanted as many of the patent segmental arteries as feasible. RESULTS: Five patients died during hospitalization, for an in-hospital mortality rate of 9.8%. The number of aortic clampings per patient ranged from one to five (median, three). A total of 124 segmental arteries were reimplanted in 44 (86.3%) of 51 patients. Of the 124 arteries, 90 (72.6%) were distributed between T9 and L2. Postoperative paraplegia or paraparesis did not develop in any of the patients. CONCLUSIONS: Our results demonstrate that extensive reimplantation of segmental arteries using sequential multisegmental aortic clamping, accompanied by adequate intraoperative distal aortic perfusion, is effective in preventing spinal cord ischemia.     

Surgical treatment of aortic arch aneurysm combined with coronary artery stenosis.

OBJECTIVE: We present operative results of aortic arch aneurysm associated with coronary artery stenosis, and evaluate the operative risk of graft replacement of the aortic arch and concomitant coronary artery bypass grafting (CABG). PATIENTS AND METHODS: From January 1991 to December 2001, we treated 16 patients with aortic arch aneurysm and coronary artery stenosis. The patients, 3 women and 13 men (study group) ranged from 58 to 79 years of age, average 68.1 5.3 years. With the aid of deep hypothermic cardiopulmonary bypass, we performed graft replacement of the aortic arch aneurysm and concomitant CABG. We bypassed 31 coronary arteries. The bypass grafts included saphenous vein (n=16), left internal thoracic artery (n=4), right internal thoracic artery (n=1), right gastroepiploic artery (n=5) and inferior epigastric artery (n=2). The number of bypassed coronary arteries per patient ranged from 1 to 3, average 2.1 0.8/patient. A comparative study was performed between the study group and a control group of patients (n=39) who had undergone only graft replacement of the aortic arch. RESULTS: There was no significant difference between the two groups regarding: operation time, cardiopulmonary bypass time, cardiac arrest time, intraoperative bleeding volume, and early mortality rate. However, in the patients (n=4) of the study group who had undergone total arch graft replacement with three vessel CABG, the cardiopulmonary bypass time was significantly longer than that of the patients in the control group who underwent total arch graft replacement (n=19, P<0.05). Two of the 16 study group patients died in the early postoperative period, resulting in 12.5% early mortality rate. In the control group, four of 39 patients (10.3%) died in the early postoperative period. CONCLUSIONS: CABG combined with graft replacement of the aortic arch does not increase operative risk when the number of bypassed vessels is within two vessels, but may increase risk when three or more vessels are bypassed.     

Retrograde double-labeling study of the mammillothalamic and the mammillotegmental projections in the rat

Collateral axonal branching from the medial or lateral mammillary nuclei to the anterior thalamus, Gudden's tegmental nuclei, the nucleus reticularis tegmenti pontis, and the medial pontine nucleus was studied using the fluorescent retrograde double-labeling method. One day after injection of Fast Blue into the anterior thalamic nuclei or Gudden's tegmental nuclei, Nuclear Yellow was injected into Gudden's tegmental nuclei or the nucleus reticularis tegmenti pontis and the medial pontine nucleus. Following 1 day survival, single- and double-labeled neurons were examined in the mammillary nuclei. The lateral mammillary nucleus contains neurons whose collateral fibers project to both the dorsal tegmental nucleus of Gudden and the ipsilateral or contralateral anterodorsal thalamic nucleus, to both the medial pontine nucleus and the anterodorsal thalamic nucleus, and to both the dorsal tegmental nucleus of Gudden and the medial pontine nucleus. The pars medianus and pars medialis of the medial mammillary nucleus contain neurons whose collateral fibers project to both the anteromedial thalamic nucleus and the ventral tegmental nucleus of Gudden, to both the anteromedial thalamic nucleus and the medial part of the nucleus reticularis tegmenti pontis, and to both the ventral tegmental nucleus of Gudden and the medial part of the nucleus reticularis tegmenti pontis. The dorsal half of the pars posterior of the medial mammillary nucleus contains a few neurons whose collateral fibers project to both the anteromedial thalamic nucleus and the rostral part of the ventral tegmental nucleus of Gudden, and to both the caudal part of the anteroventral thalamic nucleus and the rostral part of the ventral tegmental nucleus of Gudden, while the pars lateralis of the medial mammillary nucleus contains no double-labeled neurons and projects only to the anteroventral thalamic nucleus.