Thomas D. Kinney

Effect of Diet on the Glucose Tolerance and Plasma Insulin Levels of the Sand Rat (Psammomys Obesus)

When sand rats were switched from their usual all vegetable diet to laboratory chow or to a synthetic diet, most developed glycosuria, a marked decrease in glucose tolerance, and elevated plasma insulin. Some animals (all males) had a fulminating reaction with markedly decreased glucose tolerance, low plasma insulin levels and death within three weeks. Others were more resistant and did not show glycosuria at any time although their glucose tolerance tests were abnormal and their plasma insulin levels were high. Still others had an intermediate reaction with early appearance of glycosuria, decreased glucose tolerance, and elevated plasma insulin; then a gradual decrease in these diabetic signs; and finally a reappearance of abnormal glucose tolerance tests with death from severe diabetes mellitus. Since the plasma insulin level was high in most diabetic animals despite a high blood glucose level and decreased glucose tolerance, it is probable that the basic defect in these animals is not an inability to produce insulin, but rather a decrease in peripheral effectiveness of the hormone. However, the few animals that had a fulminating response were apparently unable to synthesize and release an adequate supply of insulin. Sand rats maintained on an all vegetable diet did not show these same marked signs of diabetes mellitus. However, occasional decreases in glucose tolerance were observed which, in some cases, were apparently precipitated by severe jaw infections. The caloric intake of the sand rats fed laboratory chow or the synthetic diet was significantly higher than that of the animals fed only vegetables, although the weight gained by animals on chow or synthetic food was only slightly greater or no greater than that gained by animals on all vegetables.

Xanthine Oxidase Activity and Iron Storage in the Liver.

Summary Sodium tungstate was added to the diet to decrease liver xanthine oxidase activity. There were no concomitant changes in liver iron or iron absorption associated with the decrease in xanthine oxidase activity.

Influence of transferrin saturation on the effect of intraluminal fructose or histidine on iron absorption.

Summary The influence of transferrin saturation on the enhancement of iron absorption by intraluminal histidine or intraluminal fructose was studied in rats. A loop of lumen immediately distal to the pylorus was perfused in vivo with a solution containing Fe59. The greatest amount of Fe59 absorption was noted when the perfusate was supplemented with histidine or with fructose. When the perfusate in the intestinal lumen was not supplemented, or when it was supplemented with histidine, increase in transferrin saturation did not influence the iron absorption in each instance. However, when the perfusate contained fructose, the transferrin saturation had a lessening effect on the amount of iron absorbed. Histidine supplement to the perfusate caused a rapid transit of iron across the intestinal mucosa, since there was significantly less iron retained in the mucosa in the face of a high level of iron absorption.

Depression of Liver Affinity for Iron with Iron Overload.

Summary When liver slices were incubated in Ringers solution containing Fe59 the uptake of the radioactive iron was significantly decreased if the rats were previously overloaded with iron parenterally. Oral administration of iron did not produce the same degree of overload, and subsequently there was no significant decrease in the affinity of the liver for Fe59 in vitro. The deposition of histochemically demonstrable iron in the liver was associated with the presence of a DPAS positive material and acid phosphatase.

Automation in the Clinical Laboratory

Publisher Summary A clinical laboratory has the responsibility to provide a variety of tests that give objective data for the prevention, diagnosis, and rational management of disease. Access to a dependable clinical laboratory is indispensable to every practitioner of modern medicine. A physician sees his patients in many settings, including his office, the emergency room, clinics, and hospitals, but no matter what the circumstances, he would need to call upon the clinical laboratory at some point in the diagnosis and treatment for a test of some type on a sample of fluid or tissue taken from the patients body. The physician expects the laboratory to perform all tests under carefully controlled conditions and to provide accurate results in as short a time as possible at a reasonable cost to the patient. The extent to which a clinical laboratory can fulfill these expectations depends not only upon the competence and integrity of its multidisciplinary professional and technical staff, but also on its success in substituting mechanized equipment for manual labor.