Ventral burn in rats: an experimental model for intravital microscopic study of microcirculation.

A novel technique of application of controlled ventral scald burn to rodent, whose back is inaccessible because of preburn preparation, is described. Boiling water is applied across a polyethylene membrane that partially envelops the subject. The technique is simple, economical, reproducible and allows intravital microscopic study of microcirculation in a remote muscular bed before and after burn injury.

Protein kinase C activation contributes to microvascular barrier dysfunction in the heart at early stages of diabetes.

The functional disturbance of microvasculature is recognized as an initiating mechanism that underlies the development of various diabetic complications. Although a causal relationship between microvascular leakage and tissue damage has been well documented in diabetic kidneys and eyes, there is a lack of information regarding the barrier function of coronary exchange vessels in the disease state. The aim of the present study was to evaluate the permeability property of coronary microvessels during the early development of experimental diabetes with a focus on the protein kinase C (PKC)-dependent signaling mechanism. The apparent permeability coefficient of albumin (Pa) was measured in isolated and perfused porcine coronary venules. The administration of high concentrations of D-glucose induced a dose-dependent increase in the Pa value, which was prevented by blockage of PKC with its selective inhibitors bisindolylmaleimide and Goe 6976. More importantly, an elevated basal permeability to albumin was observed in coronary venules at the early onset of streptozotocin-induced diabetes. The hyperpermeability was corrected with bisindolylmaleimide and the selective PKCbeta inhibitor hispidin. Concomitantly, protein kinase assay showed a high PKC activity in isolated diabetic venules. Immunoblot analysis of the diabetic heart revealed a significant subcellular translocation of PKCbetaII and PKCepsilon from the cytosol to the membrane, indicating that the specific activity of these isoforms was preferentially elevated. The results suggest that endothelial barrier dysfunction attributed to the activation of PKC occurs at the coronary exchange vessels in early diabetes.

Ammonium chloride potentiation of streptozotocin-induced diabetes in juvenile pigs.

In preparation for direct vital microscopic evaluation of microcirculatory dynamics in the diabetic pig myocardium, we were initially unsuccessful in inducing sustained hyperglycemia in juvenile pigs using streptozotocin according to previously reported methods. Therefore, we modified the technique in a way previously unreported in an effort to improve the success rate of diabetes induction. In the first set of 9 pigs, we followed described methods of intravenous injection with 150 mg/kg streptozotocin. In the second group of 9, the technique was modified. The change was based on human studies with ammonium chloride and animal experiments with alloxan, and consisted of the addition of a period of pretreatment with ammonium chloride. Of the nine pigs not treated with ammonium chloride, only two developed sustained hyperglycemia in excess of 17 mmol/L (300 mg/dl), and only after reinjection with a full dose of streptozotocin within 7 days of the first injection. Conversely, of the ammonium chloride pretreated pigs, eight of nine developed diabetes. We conclude that the addition of ammonium chloride to produce systemic acidosis prior to streptozotocin injection improves the efficacy of the drug.

Acetylcholine-induced and nitric oxide-mediated vasodilation in burns.

Microvascular endothelial cells actively participate in local regulation of blood flow and blood-tissue exchange by producing various vasoactive substances including nitric oxide (NO). This study examined microcirculatory changes in the early stage of thermal injury and the NO-related mechanisms. Resistance arterioles of rat cremaster muscle were observed using intravital microscopy. Arteriolar diameter and flow velocity were measured and flow rate was calculated after administration of various vasoactive agonists in burns. In fluid-resuscitated rats with stable systemic blood pressure, microvascular caliber and blood flow were not significantly altered in the first hour following a 25% total body surface area full-thickness scald burn. Topical application of acetylcholine (ACh), an endothelium-dependent vasodilator, increased arteriolar diameter and flow rate in a dose-dependent fashion. The dose-responsive effects of ACh were significantly greater in burned rats than in sham-burned rats, and the augmentation was blocked by inhibition of NO production with NG-monomethyl-l-arginine (L-NMMA). Topical application of adenosine, an endothelium-independent vasodilator, and sodium nitroprusside, an exogenous NO donor, markedly increased arteriolar diameter and flow rate. The effects were not significantly different in burned and sham-burned animals, and the adenosine-induced vasodilation was not blocked by L-NMMA. These data suggest that endothelium-dependent and NO-mediated arteriolar dilation is enhanced in the early stage of thermal injury. This effect may play an important role in the pathophysiological events of microcirculation and blood-tissue exchange in burns.

Three years behind the former iron curtain.

A Hungarian-born US heart surgeon spent more than 3 years in Hungary as a professor of surgery at a medical school. His mission was to begin invasive heart disease diagnosis and therapy. The experience was both historical--living in the past--and visionary--a look at the potential future of our economics- and politics-infested medical care.

Access to the thorax by incision.

BACKGROUND: For years the standard access to the thorax has been by posterolateral or other muscle cutting thoracotomy incisions. These are accompanied by significant discomfort and often limitation of shoulder girdle movement. To obviate these distressing features, the less traumatic median sternotomy was recommended. In the last ten years, several types of mini or axillary thoracotomies have been described. We believe that the vertical axillary thoracotomy is the best of these incisions as no major muscles are divided, it can be created rapidly, and exposure is excellent. STUDY DESIGN: We compared the operative approaches from the point of view of the duration of postoperative hospitalization, the length of the operating time, the incidence of postoperative atelectasis, and persistence of incisional pain. RESULTS: The vertical axillary thoracotomy showed a definite advantage in all these categories. CONCLUSIONS: These findings suggest that the vertical axillary thoracotomy is the incision of choice for most thoracic procedures as the incision is small and quickly made. Because there is limited division of muscles, the convalescence is smooth and uncomplicated.

Long-term follow-up of the Vineberg internal mammary artery implant procedure.

This report describes the 20-year follow-up of a patient who had undergone a double internal mammary implantation for coronary occlusive disease. A lack of similar reports in the literature suggests that such survival is rare, but this case indeed documents the fact that the internal mammary arteries can revascularize the myocardium, and this patient's continued survival appears to depend entirely on this collateral blood flow.

Migration of temporary epicardial pacer wire fragment retained after a cardiac operation.

Reported complications of retained temporary epicardial pacer wires after cardiac operations have been confined to infections. We report the migration of the retained fragment into the free peritoneal cavity after 6 years of stability in the precordium.

Carcinoma of the esophagus.

Carcinoma of the esophagus remains difficult to detect while it is localized to the mucosa. The ideal treatment is removal of all tissue that contains tumor. Usually reconstruction using the stomach is preferred over the use of gastric tubes, colon, and jejunum, although these will serve satisfactorily. Maximal palliation with relief of dysphagia is best achieved by removal of the obstructing lesion when possible, even if some tumor remains. When resection is not practical, bypass anastomoses proximal to the tumor occasionally may be used to relieve the obstruction and the associated dysphagia. Irradiation and chemotherapy may improve the results of therapy. To permit earlier detection, better screening tests are needed.

Coronary artery bypass surgery in elderly patients.

Seventy-five patients 65 years of age and older had coronary artery bypass surgery during 2 years at Scott and White Memorial Hospital with a 4 per cent mortality rate. An average of 3.1 grafts were placed and 5.1 units of blood were used during 13 days of postoperative hospitalization. Sixty-one patients were in New York Heart Association Class IV, 12 were in Class III, and 2 had other indications for coronary artery bypass. One year following surgery there were 60 patients in Class I, 6 in Class II, 3 in Class III, and 1 in Class IV; 1 patient was dead, and 4 were lost to follow-up. Our conclusion is that coronary artery bypass grafting can be performed with an acceptable mortality rate in the elderly and that age alone should not be considered a contraindication to the operation.

Duodenal ulcer: its treatment by parietal cell vagotomy at the time of cardiovascular operation.

The existence of duodenal ulcer disease constitutes a potential threat during the recovery that follows any major operative procedure. At the time of cardiovascular operations, it would be desirable to treat the coexisting duodenal ulcer disease with a definitive ulcer operation if it could be done without entering the gastrointestinal (GI) tract, thereby eliminating the risk of graft contamination. Parietal cell vagotomy with pyloroplasty meets these conditions. During an 18-month period, 309 patients underwent cardiovascular procedures; ten underwent parietal cell vagotomy at the same time for treatment of duodenal ulcer. None of the patients experienced GI complications or the development of any other operative complications referable to the gastric procedure. Parietal cell vagotomy for active duodenal ulcer disease seems to be eminently suited as a companion for cardiovascular procedures that must be expedited.