Effects of nornicotine enantiomers on intravenous S(-)-nicotine self-administration and cardiovascular function in rats.

RATIONALE: Previous neurochemical evidence indicates that R(+)-nornicotine is more potent than S(-)-nornicotine in evoking dopamine release in rat nucleus accumbens slices. OBJECTIVE: The current study tested the hypothesis that R(+)-nornicotine is also more potent than S(-)-nornicotine in selectively decreasing intravenous S(-)-nicotine self-administration in rats. RESULTS: After acute pretreatment (1-10 mg/kg for each enantiomer), R(+)-nornicotine was more potent than S(-)-nornicotine in decreasing S(-)-nicotine self-administration; in contrast, within the same dose range, the nornicotine enantiomers were equipotent in decreasing sucrose-maintained responding. This enantioselectivity does not likely reflect a difference in bioavailability, since similar levels of nornicotine were recovered from the brain 60 min after injection (5.6 mg/kg for each enantiomer). With repeated pretreatment, tolerance did not develop to the rate-decreasing effect of either nornicotine enantiomer (3 or 5.6 mg/kg) with respect to the decrease in S(-)-nicotine self-administration, although the enantioselectivity dissipated across repeated pretreatments. While both enantiomers acutely produced a similar increase in blood pressure and heart rate, tolerance developed to the blood pressure effects of R(+)-nornicotine, but not to the effects of S(-)-nornicotine, across repeated treatments. CONCLUSION: Both R(+)- and S(-)-nornicotine may have potential utility as a novel tobacco use cessation agent.

The role of vein patch in distal anastomotic intimal hyperplasia: an histologic characterization.

Comparison of the cumulative patency of four types of Polytetrafluoroethylene (PTFE) grafts with and without a vein patch at the distal anastomosis in one hundred and twenty ilio-femoral by-passes of sixty dogs revealed: (i) Vein patch improved patency in standard PTFE graft 10/16 (62.5%) versus without a vein patch 6/16 (27.5%) (p < 0.1). (ii) The less rigid thin wall PTFE graft did not benefit from vein patching 22/45 (48.8%) versus those without a vein patch 28/45 (62.2%) (p < 0.2). (iii) DAIH was present in all grafts with and without a vein patch and occurred exclusively at the heel and the toe of the graft plus the floor of the host artery three months after implantation. (iv) An organized fibrocellular multilamination characterized the cytoarchitecture of the DAIH. (v) A process of gradual cell transformation and orientation occurred in DAIH that spanned between the graft and the lumen. Vein patch at the distal anastomosis improved the patency of the more rigid standard PTFE grafts, and adversely affected the less rigid thin walled PTFE graft in dogs. The formation and distribution of DAIH was not altered by a vein patch at the distal anastomosis of PTFE grafts.

Mitral valve replacement in idiopathic hypereosinophilic syndrome.

Idiopathic hypereosinophilic syndrome is an eosinophil-mediated tissue injury causing multiple organ failure. Cardiac manifestations include subendocardial fibrosis, thrombus leading to peripheral emboli, restrictive cardiomyopathy, and valvar dysfunction. This article describes a patient with the syndrome and reviews surgical experience with valve replacement and long-term prognosis.

Pressure-controlled inverse-ratio synchronised independent lung ventilation for a blast wound to the chest.

Massive unilateral pulmonary injury poses a severe ventilatory problem. We used pressure-controlled, inverse-ratio, independent lung ventilation for a shotgun injury. Two synchronised Siemens Servo 900C ventilators were connected to a double lumen endotracheal tube. Arterial pO2 tripled in 15 minutes, and the patient remained on SILV for 36 hours.

Vein to caval bypass and insertion of suprarenal cava filter for caval occlusion.

Inferior vena cava occlusion following caval interruption (clip, plication, umbrella) for recurrent pulmonary embolism is not uncommon. Patients who are severely disabled by lower extremity venous hypertension following caval occlusion should be considered for caval bypass procedure with concomitant Greenfield filter placement. This report details such a case and outlines the management, including coagulopathy workup.

Surgical management of the acutely obstructed colon. A review of 127 cases.

The surgical results in 127 cases of acute obstruction of the colon are presented. Carcinoma continues to account for the overwhelming number of cases, and there has been no appreciable change in the site of obstruction or age groups affected. In the current study, the overall mortality rate in patients with acute obstruction from all causes was 27 percent, which does not appear to be significantly different than it was 30 years ago. The overall mortality rate in patients with obstruction secondary to carcinoma was 23 percent. Under the specific circumstances of the cases reported herein, and on the basis of a limited experience, total colectomy and left colectomy as initial procedures in acute obstruction secondary to cancer had the same mortality rate as staged resection of the left colon. The only benefit found from either approach was an increase in the disease-free 5 year survival rate with staged resection. The overall survival rate was not enhanced by either approach.

Sequential coronary artery bypass utilizing the internal mammary artery.

Fifty consecutive patients underwent sequential bypass grafting of diseased coronary arteries using the left internal mammary artery (IMA) as a sequential bypass graft. There were no perioperative myocardial infarctions, and follow-up from 3 to 5 years revealed that all 50 patients are living and are free of angina. Technical aspects for use of the internal mammary artery as a sequential graft to two or more coronary arteries is technically a feasible procedure when certain guidelines are followed. We advise its use primarily for left anterior descending/diagonal connections and avoid its use when there is a wide angle between the latter vessels to avoid kinking. The distal end-to-side IMA anastomosis is always performed first to the most important coronary artery. With this approach if there is a problem with length or lie of the IMA graft, the sequential anastomosis to the lesser important coronary artery may be aborted. The side-to-side technique is used most often. Postoperative angiograms in 11 patients have revealed no evidence of stenosis, occlusion, or late ill effects.