Benjamin N. Berg

Spontaneous Nephrosis, with Proteinuria, Hyperglobulinemia, and Hypercholesterolemia in the Rat.∗

Summary A form of spontaneous nephrosis characterized by proteinuria, hyperglobulinemia and hypercholesterolemia occurs in the Sprague-Dawley rat. Proteinuria exists at weaning, and microscopically observed changes appear at 60 days of age. Degree of proteinuria corresponds with severity of lesions, and both increase with age. In young rats, globulin is the chief protein component excreted in the urine. In older animals, the albumin fraction predominates. Serum globulin increases with age, but serum albumin shows little change. Hypercholesterolemia is observed in 640-day-old rats.

Bactericidal Function of the Liver.

During the course of our studies on the effects of intestinal stasis on blood destruction and regeneration, some experiments were undertaken to determine the rôle of the liver and bile in the elimination of bacteria in normal fasting dogs. Several investigators 1 have found organisms in the tissues of apparently normal animals. Wolbach and Tadasu 2 found an anaerobic spore-bearing bacterium in the livers of 21 out of 23 healthy dogs. These authors obtained their material from dogs which were killed by chloroform. The interval between the last feeding and the death of the animal was not stated. They were unable to grow the organisms obtained from the liver in sterile bile, or bile containing media. The material for our studies was obtained under strict aseptic conditions from 11 normal dogs which had been kept without food for 18 hours. Ether anesthesia was used. The specimens consisted of blood from the portal vein (obtained in 5 dogs), bile from the gallbladder, and a wedge-shaped piece of liver measuring approximately 3 cm. × 2 cm. In addition, the organisms which were obtained from the liver tissue were incubated in undiluted and diluted bile (1:10 to 1:1,000,000). The organisms and bile were obtained from the same animal in each instance. Cooked meat dextrose broth was used as the culture medium. Strict anaerobiosis was maintained. Aerobes as well as anaerobes of intestinal origin develop satisfactorily under these conditions. 3 The liver tissue was also cultured aerobically. In every dog the bile was sterile. The liver tissue from all the animals yielded a pure culture of an anaerobic spore-bearing bacterium which was similar to the one described by Wolbach. In 3 dogs the organism was identified as B. welchii; in the others the organism was not identified.

Duodenal Ulcers Produced on a Diet Deficient in Pantothenic Acid.

It is well known that various nutritional essentials are concerned with the maintenance of normal epithelial tissue. As part of a program concerning nutritional deficiencies and gastrointestinal epithelium, we have reported the finding of marked antral gastritis on calcium deficient diets. 1 Similar, less marked and less constant lesions were also reported on thiamine deficiency. Under various conditions of inanition the fundic mucosa will show rather typical areas of hemorrhage. 2 Previously, many papers have appeared on the involvement of nutritional deficiencies in the production of hyperplasia of the forestomach epithelium of rats. 3 In none of these cases, even when modifications were introduced to accentuate the process, have penetrating lesions been observed which could in the narrower sense of the word be designated as ulcers or which resembled typical ulcers as they occur spontaneously in man. Further observations have shown that on a diet deficient in pantothenic acid penetrating ulcers are produced in rats. The diet contained all the known nutritional factors necessary for growth except pantothenic acid, and had the following composition per 100 g of diet: vitamin “free” casein (Labeo) 18.0; cerelose 71.9; salt mixture 6.1 (Ca 1.0, P 0.55); cottonseed oil 2.0; celluflour 2.0. Incorporated in the oil were 10 mg alpha tocopherol and 1500 international units of vitamin A as carotene. The celluflour carried: thiamine HO and pyridoxine HO 1 mg each; riboflavin 2 mg; niacin 4 mg and 2-methyl-naphthoquinone 0.5 mg. Out of a larger group covering various age ranges, 45 animals have been autopsied: 23 older rats with an initial age averaging 394 (271-620) days and 22 younger rats starting at 42 to 105 days. The average experimental time for the older animals was 100 (67-140) days and for the younger one 125 (87-185) days.

Effect of thyroxine on spontaneous nephrosis in the rat.

Summary Long-term administration of thyroxine to adult rats at a level that produced a 50% increase in O2 consumption, increased the severity of spontaneous nephrosis and proteinuria. The amount of excreted protein corresponded roughly with severity of renal lesions. The electrophoretic pattern of the urinary proteins of untreated or treated rats resembled that of the serum proteins. Hyperglobulinemia was present in both untreated and treated rats, but to a lesser degree in 600-day-old thyroxine-treated animals with greatest proteinuria and elevated BUN values. In the latter rats serum albumin was reduced too. Hypercholesterolemia was greater in treated rats than in untreated ones. Kidney, heart, and adrenal weights were also higher in animals receiving thyroxine, whereas body weight was lower.

Comparative Frequency of Peptic Ulcers After Deprivation of Bile and Pancreatic Juice

Berg and Jobling 1 reported the occurrence of peptic ulcers in dogs following the deprivation of bile. These findings were corroborated by Kim and Ivy 2 and Bollman and Mann. 3 The incidence of ulcers was approximately 60%. During the past few years, in connection with other investigations, we have examined a number of animals deprived of their pancreatic secretions by means of fistulas, ligation of the pancreatic ducts, and pancreatectomy, and have been impressed by the infrequent occurrence of peptic ulcers in these animals compared to dogs in which bile was excluded. On the other hand, Elman and Hartmann 4 found ulcers in the duodenum in all of the animals of a series of 6 dogs with pancreatic fistulas existing from 13 days to 18 days. They described the lesions as ulcers, although microscopic examination revealed only defects in the continuity of the mucosa, not involving the deeper muscular layers of the intestine. These investigators attributed the lesions to the loss of the neutralizing effect of pancreatic juice upon gastric acidity, and minimized the importance of bile as a factor in the development of peptic ulcers in dogs. The following observations were made upon a series of 14 dogs deprived completely of pancreatic juice by means of fistulas made according to the technique of Rous and McMaster, as adapted by Elman and McCaughan. 5 Twelve of the animals received sodium chloride by mouth or intravenously; 2 received no special form of treatment and were killed after 25 days and 31 days respectively. Some of the animals were killed while they were still in good condition. Others developed symptoms typical of pancreatic insufficiency 6 and died spontaneously.

Calcium deficiency and gastric lesions in the rat.

Conclusions Antal gastric lesions in the rat are produced by calcium deficiency.

A Study of the Islands of Langerhans in vivo With Observations on the Circulation

Studies of the pancreas with an intact circulation were made in the living animal by Kuhne and Lea, 1 Mathews 2 and Covell. 3 The following report deals with the physiology of the islands of Langerhans in the pancreas of a living mammal with observations on the circulation. The pancreas of the white mouse was the most satisfactory for this purpose. Male mice weighing from 10 to 20 gm. were used. Anesthesia was induced by the subcutaneous injection of 1 mgm. of sodium amytal (Eli Lilly & Co.) per 5 gm. of body weight. After 10 to 20 minutes narcosis was complete. The animal was placed upon its right side in a petri dish that rested upon a warm stage. An incision measuring 1 cm. was made in the left flank, and the anterior pole of the spleen was grasped and drawn through the opening in the abdominal wall. By gentle traction and rotation the tail of the pancreas was brought into view, attached to the hilum of the spleen. After teasing the lobules apart to expose the main central vessels, the pancreas was bathed with physiological saline at 37°C. and covered with a small cover slip. Observations extended one to 2 hours under a binocular microscope using direct illumination. In suitable preparations the islands could be identified by the naked eye, as minute white dots on a yellow background. They were distributed usually along the course of the main central vessels or branches of the latter. Microscopically they appeared as brilliant yellowish white bodies on the surface of the less refractile yellow pancreas or on a vein. They were round, oval or kidney-shaped, had well defined margins and varied in size from 0.6 to 0.07 mm.

The Effect of Division and Transplantation of the Common Duct Upon Gall-Bladder Function.

Recent studies 1 , 2 tend to minimize the importance of the sphincter of Oddi in the regulation of gall-bladder activity. However, the methods which have been employed to eliminate the action of the sphincter are open to a number of criticisms. We have attempted to avoid them by completely dividing the common duct proximal to the sphincter and implanting the stump into another part of the duodenum. The effect of this procedure upon the action of the gall-bladder was determined by means of cholecystograms which were made according to the method described by Graham and his co-workers. 3 Under ether anesthesia, the common duct in 2 dogs was isolated and doubly ligated just above its entrance into the duodenum. A linear incision 2 cm. long was made in the anterior surface of the duodenum about 8 cm. from the pyloric sphincter. The duct was divided 1/2 cm. proximal to the ligature, and fixed at the lower angle of the opening in the duodenum, which was then closed by two sutures. Six weeks and 8 weeks respectively, after the operation, cholecystograms were obtained in the following manner: 0.12 gms. sodium tetraiodophthalein per kilo body weight were injected intravenously. Eighteen hours after the injection of the dye, the first X-ray film was taken. Then the dogs were fed with the yolks of 3 eggs in 200 cc. of cream 4 and films were taken at intervals of 1, 3, 6 and 24 hours after the meal. In both dogs, the shadow was normal in size and density at the 18th hour observation. Following the meal, in one dog, there was progressive shrinkage and increased density of the shadow, with complete disappearance at the 24 hour period.

The Time Factor in the Production of Gastric Lesions on Low Calcium Diets

Summary Keeping rats for longer periods of time on low calcium diets accentuates the ulcerative as well as the hyperplastic and hemorrhagic character of the antrum lesions as against the conditions produced in 4 weeks. It also brings out a generalized tendency to bleeding. No perceptible change, however, is produced with regard to penetration, the lesions remaining superficial.

Further studies on continuous secretion of the pancreas.

In a previous communication 1 observations were presented which indicate that in the dog pancreatic secretion is continuous during interdigestive periods, as it is in rabbits and ruminants. In another paper 2 we have discussed the inhibitory effect of ether anesthesia on continuous secretion, which explains the absence of continuous flow in the acute experiments of Bayliss and Starling. It has been claimed that continuous secretion in permanent fistulas is due to lack of neutralization of gastric hydrochloric acid by the pancreatic juice diverted from the intestine. 3 In order to determine whether this factor has an effect on continuous secretion the following experiment was performed. A dog was prepared with a system of altercursive intubation as described by Elman and McCaughan 3 by means of which the pancreatic juice was continuously returned to the intestine through the biliary tract. This consists of an intercommunicating system of tubes leading from the pancreas to the gall bladder in such a way that the flow of juice can be observed on the outside. By this procedure the pancreatic secretion was allowed to enter the duodenum through the ampulla of Vater and neutralization of the gastric juice could take place as in the normal animal. Elman 4 states that the gastric hypersecretion which he reports as accompanying complete drainage of pancreatic juice to the outside, does not occur under these conditions.