Changes in the linear attenuation coefficient of canine appendicular bone following intravenous infusion of strontium lactate, measured using gamma-ray computed tomography.

Changes in the average linear attenuation coefficient (LAC) within a fixed measurement volume in the proximal end of the dog tibia, which contains trabecular bone and associated soft tissues (the trabecular bone "space"), were monitored continuously using gamma-ray computed tomography (gamma-CT) prior to, during, and following intravenous infusion of strontium (Sr) lactate. An infusion of 1.3-4.7 g of Sr over a period of 110-160 minutes into 20-kg dogs resulted, within 6-8 hours, in an increase of 0.019-0.045 cm-1 (P less than 0.002) in the LAC. Calibration of the gamma-CT system showed that 0.44 mg/cm3 of Sr produced a change of 0.01 cm-1 in the LAC. Using this conversion factor, the Sr concentration in the trabecular bone space resulting from infusion, as measured by flame atomic absorption spectroscopy, agreed with that predicted by the change observed in the LAC. Sr present in the serum and urine was consistent with the changes observed in the LAC over the study period. Control dogs infused with mineral-free solutions showed no change in LAC. Calcium equivalents required to give the changes observed in the LAC using Sr indicate that variations in skeletal turnover in man can be monitored in the peripheral skeleton using gamma-CT.

Low-temperature cryopreservation of BB rat embryos of spontaneously diabetic rats.

Cryopreservation of BB rat embryos would ensure perpetuation, at greatly reduced cost, of this model of nonobese, insulin-dependent, juvenile-onset diabetes in man. Immature prediabetic female BB rats were ovulated hormonally. The embryos were removed at the 8- to 16 cell and blastocyst stages and cryopreserved, and after thawing were assayed for viability in vitro or transplanted into pseudopregnant foster mothers of a nondiabetic strain. The highest rate of viability in vitro (100%) and development into normal fetuses (31%) was obtained with blastocysts transplanted into day-4 foster mothers. The results indicate the feasibility of low-temperature banking of this clinically important strain of rats.

The in situ measurement of strontium content in bone using x-ray fluorescence analysis.

A technique is described which uses x-ray fluorescence to determine in situ the strontium content of bone. Measurements were made of the skulls of seven rabbits both before and after a single bolus injection of strontium was administered intravenously. The retention of strontium was followed for up to eight months and could be represented either by a three-exponential model or, for data obtained between 12 and 252 d following injection, the power function At-b, where t is the time in days following injection. The three-exponential terms had linear coefficients of similar magnitude and half lives of 3-4 h, 10-40 d and 200-300 d. The exponent of the power function was 0.25-0.57. Measurements were also made of the skull and medial surface of the tibial crest of an adult dog for four months following subcutaneous administration of strontium. The results obtained using x-ray fluorescence are found to be similar to those reported by others for radiostrontium studies. The precision and errors associated with the fluorescence technique are discussed. Estimates of radiation dose are given. It is concluded that the technique may serve to determine in situ the strontium content of bone near the surface of the body.

Prevalence of rabies virus in foxes trapped in the Canadian Arctic.

Brains and salivary glands of 521 trapped arctic foxes (Alopex lagopus) submitted from four different settlement areas in the Northwest Territories were examined for rabies by the standard fluorescent antibody and mouse inoculation tests. Rabies antigen was present in 44 of 201 (21.9%) brains from foxes trapped in the Sachs Harbour area, but submissions from Cambridge Bay (127), Spence Bay (93) and Gjoa Haven (100) were negative. Virus was also present in salivary glands from 43 (97.7%) of these 44 positive foxes. The arctic fox continues to be the main wildlife reservoir of rabies in the Canadian Arctic and foxes in the prodromal stage of the disease pose a particular threat to the trapper. Preexposure vaccination should always be a consideration in this occupational group.

Urine production in the halothane anesthetized rabbit.

Urine and blood parameters were studied in rabbits subjected to anesthesia and abdominal surgery. Conscious control animals both fasted and fed to which water was freely available were used for comparison. During anesthesia and operation one group of animals were given no intravenous fluid, other groups were infused with normal saline at a rate of 0.5 ml, 1 ml, or 2 ml per minute. The results demonstrated that an intravenous saline infusion of 0.5 ml per minute, maintains an essentially normal state of hydration and is beneficial to rabbits during anesthesia and surgery. However, with such an infusion, the rabbits do not produce urine under the experimental conditions. Higher rates of infusion are associated with a declining heart rate and blood pressure, abnormal urine, and metabolic acidosis. We conclude that the rabbit is an inappropraite species for renal studies involving anesthesia and surgery.

Some intestinal parasites of Arctic fox, Banks Island, N. W. T.

Small intestinal parasitology of 50 trapped Arctic fox taken on Banks Island, The Northwest Territories, showed a prevalence of Taenia crassiceps (78%), Toxascaris leonina (60%), Echinococcus multilocularis (2%) and Coccidia (2%). Attention is drawn to the absence of Toxocara sp. and of Uncinaria sp.

Composition of gastric mucinous secretion from Heidenhain pouches of dogs treated with aspirin.

Principal glycoproteins and amino acids of secretions from Heidenhain pouches were studied in control and aspirin-treated dogs in the resting state of fasting and during stimulation with pentagastrin. All samples showed the presence of galactose, galactosamine, glucosamine, glucose, fucose, mannose, uronic acid and sulfate. Galactose and glucosamine were found in equimolar amounts, and the galactose/galactosamine ratio was 2/1. Pentagastrin induced the reduction in concentration of major carbohydrate components and amino acids of gastric mucus. The concentrations of major carbohydrate components and of amino acids of gastric secretions were lower in aspirin-treated animals than in controls.

The effect of L-amino acids given intravenously on gastric secretion stimulated by pentagastrin in dogs.

L-Amino acid solution given intravenously in Heidenhain pouch dogs resulted in marked changes of both basal and pentagastrin-stimulated gastric secretions. During a 1-hour amino acid infusion, a significant augmentation of pentagastrin-induced secretion was observed. A significant increase of secretion during amino acid infusion was also found in dogs not infused with pentagastrin. Absolute values of HCl output were much higher in dogs in which secretion was stimulated by a combination of pentagastrin and amino acids than by amino acids alone. This increase was followed by a fall of gastric secretion in response to pentagastrin.

Gastric mucinous secretion under various conditions of stimulation in hypothyroid dogs.

Principal glycoproteins and amino acids of the secretions from Heidenhain pouches, were studied in normothyroid and hypothyroid Labrador dogs in the resting state, following injection of pentagastrin, histamine and after feeding. Hypothyroidism was produced by total thyroidectomy and chronic treatment with thiouracil. All samples showed the presence of galactose, glucosamine, galactosamine, fucose, mannose, uronic acid and sulfate. Galactose and glucosamine were found in equimolar amounts and the galactose to galactosamine ratio was 2:1. Concentrations of most carbohydrate components studied were higher in normothyroid than in hypothyroid dogs. Concentrations of most amino acids analyzed were also higher in normothyroid than in hypothyroid dogs, following stimulation with secretagogues.

Effects of adrenergic stimulation on the choledochoduodenal sphincter mechanism.

The object of this study was to access the effects of systemic bolus injections of epinephrine and of norepinephrine upon the sphincter at the choledochoduodenal junction in the cat and the dog. The bile duct was transected and the downstream segment was cannulated. Two methods were used to assess sphincteric activity. In method I the bile duct was perfused with Ringer's solution at a constant pressure and the flow rate of the solution was recorded. In method II the bile duct was perfused at a constant rate of flow and the terminal intraductal pressure was recorded. Intraduodenal pressure and respiratory movements were also recorded. There was a significant decrease in sphincteric activity following both epinephrine and norepinephrine administration in both cats and dogs, using both constant pressure and constant flow methods.

Histamine-stimulated gastric secretion in rats with chronic renal insufficiency.

Chronic uremia was induced by long-term maintenance of rats which had undergone sub-total nephrectomy, with sham-operated rats serving as controls. Chronic gastric cannulas and chronic vascular catheters (vena cava) were installed and the rats were stimulated with intravenous infusion of histamine. In uremic rats, the volume of gastric juice, output of HC1 and H+ concentration were significantly higher than in the controls during the 6-hour secretion experiments.

Mucinous secretion from canine Heidenhain pouch after stimulation with food, pentagastrin and histamine.

Principal glycoproteins and amino acids were determined in gastric juice obtained from Heidenhain pouches of Labrador pure-bred dogs. Secretions were stimulated by food, pentagastrin or histamine. Non-stimulated fasting secretions served as controls. All samples showed the presence of galactose, glucosamine, galactosamine, fucose, glucose, mannose and sulfate. Galactose and glucosamine were found in equimolar amount and the galactose to galactosamine ratio was 2:1. Concentrations of most carbohydrate components studied were higher in fasting than in stimulated secretions. Outputs of some of these components were lower in fasting than in stimulated secretions. Modes of stimulation used did not significantly affect the outputs of principal glycoproteins studied. Compared with human gastric secretions studied by others, using similar methods, certain differences were found particularly in the relationship between some carbohydrate components and between amino acids.

Plasma free amino acids in the chronically uremic rat.

Plasma free amino acids in the sub-totally nephrectomized chronic uremic rat have been quantitated. The concentrations of these substances in uremic rats have been compared to levels present in sham-operated controls, and to levels found in normal rats on a restricted diet. Phosphoserine, alpha-aminoadipic acid, 1-methylhistidine and 3-methylhistidine concentrations were found to be significantly higher in the uremic group. Sub-normal amounts of serine, valine, tryptophan, asparagine and anserine were present in the serum of the uremic animals. No changes were detected in serum amino acids which are ketogenic. Serum glutamic oxaloacetic transaminase activity was reduced in both uremic and restricted diet rats.

Carbohydrate metabolism in the chronically uremic rat.

The sub-totally nephrectomized chronically uremic rat has been found to have significantly increased hepatic glucose-6-phosphate dehydrogenase activity and increased lipogenesis and glycoportein synthesis. Increased conversion of 14-C-D-glucose to 14-CO2, and increased plasma free fatty acid levels were also observed. The metabolic significance of these findings has been discussed, particularly with respect to the importance of the pentose shunt in this model. The influence of reduced diet intake, resulting from uremic anorexia, has been considered in light of changes observed. It is concluded that decreased food intake alone is unlikely to be responsible for the altered glucose utilization evident in this model.

Carbohydrate metabolism in the chronically uremic rat.

The glycogen cycle enzymes amylo1,6-glucosidase, glycogen synthetase (I and D forms) and alpha-glucan phosphorylase (a and b forms) have been assayed for activity in skeletal muscle and hepatic tissues of chronically uremic rats. Significant decreases in muscle amylo-1,6-glucosidase (41%), hepatic phosphorylase (30%) and hepatic synthetase D (30%) activities were observed in uremics, as compared to both sham operted and destricted diet intake controls. Changes in phosphorylase "a" to "b" activity ratios and synthetase I to D activity ratios were found in the uremics. The biochemical significance of these alterations are discussed.

The effects of swimming and running regimens on skeletal muscle glycogen in the rat.

Endurance capacity and the effects of different post-exercise states on skeletal muscle glycogen have been studied in rats trained by swimming or running and in sedentary controls. Regular endurance exercise resulted in increased skeletal muscle glycogen stores. A greater depletion was observed in trained animals than in non-trained animals after a training bout or exhaustive exercise. While muscle glycogen levels did not reflect a differential training stimulus (running vs swimming), swimming as a measure of exhaustive exercise was deemed invalid because of the ability of trained swimmers to avoid stenuous exercise by an alteration of swimming pattern.

The influence of chronic uremia on hepatic glycogen in the rat.

Long term maintenance of male Wistar rats following sub-total nephrectomy has been shown to alter carbohydrate metabolism. These rats frequently became hypoglycemic and concurrently demonstrated increased hepatic glycogen stores. Chemical analysis of glycogen revealed a significant increase in branching, with a concomitant decrease in glucose residues per segment. The influence of food intake and glycosuria are discussed. Decreased glycogen autolysis is attributed to increased glycogen branching in the uremic liver.

Mucinous secretion of totally isolated porcine stomach perfused with homologous blood.

Principal glycoproteins and amino acids were determined in porcine gastric juice obtained from totally isolated stomachs perfused extracorporeally with homologous blood. Acid juices collected during prolonged stimulation of stomachs with histamine or pentagastrin, infused into gastric arteries, were used. All samples showed the presence of glactose, glucosamine, galactosamine, fucose, mannose and sulphate. Galactose and glucosamine were found in equimolar amounts and the galactose to galactosamine ratio was, in most samples, 2:1. Compared with human non-stimulated gastric juice studied by others, marked differences were found in the relationship between carbohydrate components and between amino acids. Porcine gastric juice contained much more protein than human gastric juice. Some characteristics of porcine mucinous secretion may be due to conditions of juice collection from the isolated gastric preparation.