Sarr, M. G.

Carbon monoxide (CO) is a low molecular weight oxide produced endogenously from fatty acids and heme protein. A physiological role for CO has been suggested for vascular smooth muscle, hemostasis, and olfactory neurons, but direct evidence is lacking. Heme oxygenase, which catalyzes the formation of CO from heme proteins, is present in small intestinal smooth muscle. The effect of 1% CO on whole cell currents in normal human jejunal circular muscle cells was studied with the use of a perforated patch-clamp technique. A 1% CO-containing Krebs solution caused an initial and transient increase in whole cell current in 20 of 22 cells tested (175 +/- 40%, mean +/- SE) and a transient hyperpolarization (15.6 +/- 3.6 mV, mean +/- SE) of the membrane potential. During prolonged recordings, 1% CO evoked ongoing cyclic increases and decreases in the whole cell current. Each current increase was accompanied by a sharp membrane hyperpolarization. These data suggest that CO may modulate whole cell potassium current and membrane potential.

Abstract Occasionally pancreatoduodenectomy is performed for clinically suspected pancreatic malignancy only for the surgeon to find that a benign aetiology accounts for the pancreatic mass. The aim of this study was twofold: to determine the incidence of pancreatoduodenectomy performed for a misdiagnosis of pancreatoduodenal malignancy and to identify potentially avoidable errors in preoperative and intraoperative judgement. Between 1956 and 1990, radical pancreatoduodenectomy was performed in 603 patients at the Mayo Clinic; 29 (5 per cent) underwent pancreatoduodenectomy for a diagnosis made before and during surgery of primary pancreatic or periampullary malignancy that was later proven histopathologically to be either unsuspected subacute or chronic pancreatitis (22 patients), benign fibrous common bile duct stricture (two), and penetrating duodenal ulcer, metastatic melanoma, ampullary adenoma, intrahepatic drug-induced cholestasis and pseudocyst (one each). No patient had a preoperative diagnosis of chronic pancreatitis. Weight loss, pain and/or jaundice were present in 27 of the 29 patients. Objective imaging tests, such as computed tomography, ultrasonography and/or endoscopic retrograde cholangio-pancreatography, were performed in 25 patients. Potential errors in judgement may be avoided by a more aggressive attempt at biopsy in selected patients; in others, resection for presumed malignancy may be unavoidable.