Manipulating thyroid status alters endoplasmic reticulum calcium homeostasis in rat cerebellum.

Thyroid-related hormones regulate the efficiency and expression of sarco-endoplasmic reticulum calcium ATPases in cardiac and skeletal muscle. However, little is known about the relationship between thyroid hormones and calcium (Ca2+) homeostasis in the brain. It is hypothesized that manipulating rat thyroid hormone levels would induce significant brain Ca2+ adaptations consistent with clinical findings. Adult male Sprague-Dawley rats were assigned to one of three treatment groups for 28 days: control, hypothyroid (6-n-propyl-2-thiouracil (PTU), an inhibitor of thyroxine (T4) synthesis), and hyperthyroid (T4). Throughout, rats were given weekly behavioral tests. Ca2+ accumulation decreased in the cerebellum in both hyper- and hypothyroid animals. This was specific to different ER pools of calcium with regional heterogeneity in the response to thyroid hormone manipulation. Behavioral tasks demonstrated sensitivity to thyroid manipulation, and corresponded to alterations in calcium homeostasis. Ca2+ accumulation heterogeneity in chronic hyper- and hypothyroid animals potentially explains clinical manifestations of altered thyroid status.

Annexin 7 mobilizes calcium from endoplasmic reticulum stores in brain.

Mobilization of intracellular calcium from inositol-1,4,5-triphosphate (IP3)-sensitive endoplasmic reticulum (ER) stores plays a prominent role in brain function. Mice heterozygous for the annexin A7 (Anx7) gene have a profound reduction in IP3 receptor function in pancreatic islets along with defective insulin secretion. We examined IP3-sensitive calcium pools in the brains of Anx7 (+/-) mice by utilizing ATP/Mg(2+)-dependent (45)Ca(2+) uptake into brain membrane preparations and tissue sections. Although the Anx7 (+/-) mouse brain displayed similar levels of IP3 binding sites and thapsigargin-sensitive (45)Ca(2+) uptake as that seen in wild-type mouse brain, the Anx7 (+/-) mouse brain Ca(2+) pools showed markedly reduced sensitivity to IP3. A potent and saturable Ca(2+)-releasing effect of recombinant ANX7 protein was demonstrated in mouse and rat brain membrane preparations, which was additive with that of IP3. We propose that ANX7 mobilizes Ca(2+) from an endoplasmic reticulum-like pool, which can be recruited to enhance IP3-mediated Ca(2+) release.

Modification of port-access coronary artery bypass in high-risk patients.

BACKGROUND: Minimally invasive port-access coronary artery bypass surgery has many potential advantages over routine median sternotomy coronary revascularization in patients with serious co-morbid conditions. The common femoral artery and vein have been the standard peripheral cannulation and balloon deployment sites. However, these sites present some risk, especially from proximal arteriosclerotic or aneurysmal disease. METHODS: We utilized Heartport endovenous and endoaortic cannulas (Heartport Inc, Redwood City, CA) for axilloaxillary or femoral-descending aortic cardiopulmonary bypass in 9 patients in an attempt to avoid potential cerebral and systemic embolization. All patients were successfully cannulated and the endoaortic clamp was deployed to perform a total of eleven grafts (five right coronary arteries and six circumflex coronary arteries). The patients ranged from 66 to 80 years of age. Five patients had abdominal aortic aneurysmal disease and 4 had severe peripheral vascular disease. RESULTS: All patients achieved full cardiopulmonary bypass with flows in excess of 3 L/min. without difficulty. There were no complications referable to the arm and its neurovascular structures. All axillary arteriotomies were closed primarily, without the need for thrombectomy or reconstruction. There were no neurological complications and 30-day survival was 100%. Three patients underwent successful abdominal aortic aneurysm resection prior to discharge. CONCLUSIONS: Axilloaxillary and femoral-descending aortic cannulation utilizing standard Heartport cannulas (Heartport, Inc) offer alternative sites for cardiopulmonary bypass in patients with severe peripheral vascular disease.

Single hospital experience with emergency cardiopulmonary bypass using the portable CPS (Bard) system.

One hundred four patients were placed emergently on the Bard CPS portable femoro-femoral bypass system over a 4 year period. Thirty-two patients (31%) were discharged from the hospital. Seventy-six of these patients (73%) required emergency bypass following cardiac arrest, and twenty-eight patients (26%) were in cardiogenic shock or respiratory failure. In the arrest group, no one survived an unwitnessed arrest and those with cardiopulmonary resuscitation times less than 30 minutes had a better survival rate. The highest survival rate was in those patients who did not arrest prior to bypass. Fifty-two percent of these patients were released. The 74 patients receiving interventional therapy on bypass had a higher survival rate than those unable to be treated. Of the thirty patients receiving no intervention, only three (10%) were eventually discharged. For the 19 patients receiving treatment only in the cardiovascular laboratory, the discharge rate was 26%. Of the 55 patients taken to the operating room for surgical correction, 24 (44%) were discharged from the hospital. No patients placed on bypass at an outlying hospital or treated using CPS within 72 hours of a previous open heart procedure survived.

Splenic arteriovenous fistula causing massive ascites: a case report.

A case of splenic arteriovenous fistula leading to portal hypertension and ascites is presented. The recognition of this vascular lesion is important. When portal hypertension is secondary to a splenic arteriovenous fistula, the complications of portal hypertension can be avoided by the resection of the lesion. The diagnosis can be suspected by clinical findings and confirmed by angiographic delineation of the fistula. Surgical resection of splenic arteriovenous fistulae must include the fistula and all dilated venous tributaries to prevent thrombosis and recurrent portal hypertension.

Coronary artery bypass graft surgery: relative efficacy of initial proximal versus distal anastomoses.

Controversy exists concerning the most appropriate sequence of anastomoses in coronary artery bypass grafting (CABG) procedures. While the more commonly employed method of distal coronary anastomoses first has withstood a long clinical experience, a recent study and several cardiac surgical groups have suggested that construction of the proximal anastomoses first offers certain advantages. In 30 patients undergoing CABG, we performed a prospective, randomized trial comparing both techniques. Relative efficacy was assessed by hemodynamic, radionuclide, electrocardiographic, enzymatic, thermographic, and clinical evaluation. The length of cardiopulmonary bypass was longer in the group having the distal anastomoses done first. Myocardial temperature mapping was similar between groups. Hemodynamic changes, including cardiac output, ejection fraction, and regional wall motion, were nearly identical between the groups. The incidence of myocardial damage reflected by levels of myocardial-specific isoenzymes (serum CK-MB) and electrocardiographic changes was also similar. In conclusion, the sequence of anastomoses is not critical in routine CABG operations. However, we speculate that each technique may have certain advantages under different clinical circumstances found on occasion. Ideally, each method should be part of the coronary surgeon's armamentarium.

Preliminary experience with intraoperative transluminal balloon-catheter dilation and coronary artery bypass grafting for the treatment of symptomatic diffuse coronary artery disease.

Transluminal balloon-catheter dilation of coronary artery lesions has become increasingly common in the cardiac catheterization laboratory. We describe a method of intraoperative dilation that may improve surgical results when used in combination with coronary artery bypass graft (CABG) operations in patients with diffusely diseased coronary arteries. In 16 patients, long-segment intraoperative dilations were performed to enlarge luminal narrowings in 21 different regions. All of these patients had postoperative coronary angiography and left ventriculography so that we could objectively evaluate the coronary dilatations. There were no operative deaths or perioperative myocardial infarctions, and angina was relieved in all patients. Of the 21 dilated segments, 12 (57%) were unchanged, 2 (10%) became worse, and 7 (33%) were improved postoperatively. In addition, two new areas of intimal damage were detected in patients with unchanged postoperative liminal diameters. We conclude that further experience and longer follow-up are necessary before the efficacy of intraoperative coronary artery balloon-catheter dilation can be accurately determined.