William V. Lumb

Comparison of seven suture materials in infected wounds— An experimental study

From the Surgical Laboratory, Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State Universit,y, Fort Collins, Colorado 80521. * Tutorial Fellow in the Department of Clinical Studies, Faculty of Veterinary Medicine, University of Nairobi, Kenya. t Associate Professor in the Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado 8052,l.

Inverse effect of chronically elevated blood flow on atherogenesis in miniature swine

Professor and Director of the Diagnostic Laboratory, Department of Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado 80521. 5 Professor and Director of the Surgical Laboratory, Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado 80521. From a thesis submitted by the first author in partial fulfillment of the requirements for the M.S. degree in Surgery. Research supported by Davis and Ceck Division of American Cyanamid Company and the United States Agency for International Development. Requests for reprints should be addressed to Dr. W. V. Lumb. Submitted for publication December 7, 1973. INTRODUCTION

A model to study acute pancreatitis in the dog

The effect of chronically elevated blood flow on the development of atherosclerosis in miniature swine was studied. Fistulas connecting the right external iliac artery and vein were surgically created in four swine, while three were not fistulated. Pulsed Doppler velocity detection cuffs placed around the abdominal aorta and both iliac arteries of all pigs permitted chronic measurements of blood velocity, blood velocity distributions, and blood flow. All swine were fed an atherogenic diet consisting of 20% beef tallow, 3% cholesterol, and 5% cholic acid for 6 months. This diet elevated the serum cholesterol to values exceeding 500 mg/100 ml. Creation of the arteriovenous fistula (AVF) markedly elevated blood velocity and flow in the abdominal aorta and in the shunted iliac artery. In the shunted animals the aortic blood flow was 42.1 +/- 2.0 ml/sec compared with 17.3 +/- 1.4 ml/sec in the unshunted swine. The velocity distribution pattern across the vessel was also indicative of an elevated wall shear stress. After 6 months, the animals were killed and the arterial vessels examined macroscopically and microscopically for the presence of atherosclerotic lesions. In the shunted pigs, 17 +/- 15% of the lumenal surface was occupied by sudanophilic lesions, whereas 80 +/- 8% of the surface was covered by lesions in the unshunted (control) pigs. From these studies, it is apparent that mechanical factors related to blood flow rates can influence the development of atherosclerotic lesions in swine.

Cholesterol and bile acid turnover in miniature swine.

Abstract An acute pancreatitis model was developed which was consistently lethal and which allowed assessment of the excretory function of the pancreas without catheterization of the pancreatic ducts. The minor pancreatic duct was ligated and cut, a modified Thomas cannula was inserted in the duodenum opposite the major pancreatic duct and exteriorized on the right ventrolateral abdominal wall. This allowed production of pancreatitis by retrograde injection of bile-trypsin mixture in the major duct. The minimum lethal dose of bile-trypsin mixture, as determined in 22 dogs, was 1.02 ml of bile/kg of body weight, containing 2000 units of trypsin in each 1 ml of bile used. Injection of this mixture into the major pancreatic duct resulted in severe damage to approximately 38% of the gland. A plastic sleeve was inserted into the cannula during collections of pancreatic juice, insolating the pancreatic duct from the intestine. Collection of pancreatic secretion could be accomplished without significant contamination by intestinal content and required minimum cooperation from the dog.

Detection and characterization of nitrous oxide sites in the brain of a dog under halothane-N2O anesthesia by infrared spectroscopy

Miniature swine were fitted with indwelling cannulae at two sites in the gut and catheters in the aorta and portal vein. Ring labeled cholesterol was administered via jejunum and portal vein and various parameters of disappearance measured over 17–66 days. Conversion of cholesterol to bile acids and their subsequent disappearance from gut lumen were measured. Cholesterol disappearance was found to follow a two component exponential in serum and three components in gut. The serum curves were similar to those reported for humans. It was concluded that the minipig is an advantageous model for cholesterol turnover studies and that serum and gut cholesterol dynamics are different.

Evaluation of Analgesic Drugs in Horses

Infrared spectra of N2O in a variety of solvents and in the brain of a dog under typical conditions of halothane-N2O anesthesia have been determined. The appearance or disappearance of N2O in the brain was readily followed as N2O was administered or withdrawn. The sites in brain were of two major types; one, with ν3 = 2229.8 ± 0.4 cm−1 and Δν12 = 13.0 ± 0.6 cm−1, is rather like the polar site in water and the other, with ν3 = 2216.8 ± 0.8 cm−1 and Δν12 = 9.6 ± 1.0 cm−1, is non-polar and is probably associated with membrane lipid. The significant variations in the antisymmetric stretch (ν3) of N2O as the polarity and other properties of the medium (solvent) vary make possible the characterization of in tissue sites occupied by this anesthetic.

COMBINED PHARMACOLOGIC AND SURGICAL TREATMENTS FOR ACUTE SPINAL CORD TRAUMA

Of the domesticated species of animals, horses are probably most refractory to effects of analgesic drugs. At the same time, a great need exists for effective agents that produce a sedative and analgesic effect in this species. A striking example of this occurred in 1975 when the magnificent filly, Ruffian, broke her leg in a match race at New York’s Belmont Park. She was treated by a team of four veterinarians and an orthopedic surgeon. During recovery from anesthesia she struggled desperately and destroyed the fixation device that had been applied. A decision for euthanasia was made 8 h after the race.

Portacaval shunt as treatment for hypercholesterolemia. Metabolic and morphological effects in a swine model.

Acute spinal cord trauma was induced by the Allen method at T12 in 48 dogs. Six groups of 7 dogs each were treated with combinations of pharmacologic and surgical treatments; a 7th group of 6 dogs remained as traumatized nontreated controls. Results indicate an additive therapeutic effect in those patients treated with myelotomy and dimethyl sulfoxide. Dexamethasone, reserpine, and perfusion with hypertonic dextrose solution were of no benefit.

PROSTHETIC APPLIANCE FOR REPLACING ONE OR MORE NATURAL VERTEBRAE

Since 1973 the portacaval shunt has been used as a treatment for homozygous familial hypercholesterolemia. Favorable results have been reported, but the mechanism or reduction of cholesterol is not clear. The objective of this research was to evaluate mechanisms of lipid alterations after portacaval shunting in Yucatan miniature swine. The animals were fed a high-fat diet, similar in composition to the average American diet, with or without added cholesterol. Controls were fed the atherogenic diet (+ cholesterol) for 8 months. Pigs were fed atherogenic or American diets for 8 months, then surgery (shunt or sham) was performed. They were continued on the diets for another 8 months. The vascular system was examined for the distribution and severity of atherosclerotic disease. Blood lipids and numerous biochemical indices were measured. Progression of atherosclerosis was slowed by portacaval shunting. Low density lipoprotein (LDL) concentrations were positively and high density lipoprotein (HDL) concentrations were negatively correlated with severity of atherosclerosis. Serum insulin concentrations were positively correlated with atherosclerosis. Cholesterol synthesis was increased by the shunting and decreased by cholesterol feeding. The cholesterol-fed swine is not an adequate model for familial hypercholesterolemia, but the results are consistent with inhibition of the atherosclerotic process and the involvement of lipoproteins and insulin in the mechanisms.