Biliary Excretion of Co60 Labeled Vitamin B12 in Dogs.

Abstract

Co") VIT. BI2 EXCRETION 81 0 " Q 0 2 4 6 8 10 12 14 16 18 20 Days o f Incubatibn FIG. 3. Effect of age of culture on rate of lactate oxidation by washed cell suspensions of M . tuberculosis strain H37Ra. Curve 1 = YO optical transmission of culture. Curve 2 = optical transmission of culture concentrated 5 times. Curve 3 = Qo,.0.066 M phosphate buffer, p H 6.4; 0.022 M lactate; 6-9 mg dry wt bacterial cells/cup; Sauton's medium.age of the bacterial cells. It is manifest from the data given that rate of lactate oxidation by washed cell suspensions increases with age of the cells, reaching a maximum between the 10th and the 12th day of incubation which coincides with the middle of the logarithmic phase of growth. Upon continued incubation, rate of lactate oxidation falls rapidly reaching a minimum during the stationary phase of the bacterial growth cycle. Thus, it is evident that the tubercle bacillus responds in this respect in a similar manner to other micro-organisms( 6) and suggests that young cells de-rived from dispersed cultures might properly be more widely used in studies of the physiology of this organism. Although admittedly these data were obtained using only one strain of the tubercle bacillus and inspecting only one enzyme system, the results suggest further study along these lines. Furthermore, since it has been established that the lipid content of tubercle bacilli increases with age ( 7), which may well influence the permeability of the older intact cells, it would appear desirable to utilize the younger cells for investigative purposes. Summary. A study of lactate oxidation by washed cells of M. tuberculosis strain H37Ra revealed a marked influence of the age of the cells. Cells obtained during the logarithmic phase of growth were the most active metabolically. Previous reports indicate that radioactivity *Supported by U. S. Atomic Energy Corn. and is present in bile and feces after injection of performed at Medical D e~t . , B~M -~a v e n Nat. labeled BIZ, but observation periods were short t Research Collaborator at Brookhaven from Colfollowing study was instituted to evaluate the rate of coy excretion in bile and its role as a source of fecal radioactivity after intravenous Laboratory.and data not ( ?2 j3 ) ' The lege of Veterinary Medicine, University of Minnesota.

Subnormal Concentrations of Serum Cobalamin (Vitamin B12) in Cats with Gastrointestinal Disease

“…38 The rapidity of cobalamin turnover in cats is consistent with absence of the haptocorrin in cat and dog plasma 16 and suggests that after absorption of the cobalamin-intrinsic factor complex in the ileum, cobalamin in cats, as in dogs, is bound to transcobalamin 2 and partially excreted in bile. 17 The presence of substantial amounts of intrinsic factor in the pancreas, but not the stomach, of the cat (and dog) would be advantageous in this situation and would facilitate optimal transfer of cobalamin to intrinsic factor.…”

“…Cobalamin of hepatobiliary origin, in common with dietary-derived cobalamin, undergoes transfer to IF and receptor-mediated absorption, thus establishing enterohepatic recirculation of the vitamin. 17 Low serum cobalamin concentrations in dogs have been associated with exocrine pancreatic insufficiency (EPI), severe intestinal disease, and putatively small intestinal bacterial overgrowth. [1][2][3][4]18 When low serum cobalamin is detected and EPI and small intestinal bacterial overgrowth have been excluded, localization of the problem to the ileum can be inferred.…”

Review of cobalamin status and disorders of cobalamin metabolism in dogs

“…A) . Approximately 15 μg/day of recirculating cobalamin is extracted by hepatocytes and secreted in bile bound to haptocorrin for enterohepatic recirculation . Within all eukaryotic cells, cobalamin acts as an essential cofactor for the intracellular enzymes methionine synthase and methylmalonyl‐CoA mutase (Fig.…”

Cobalamin, folate and inorganic phosphate abnormalities in ill cats

“…This results in uptake and then release of cobalamin into the circulation, where it is transported to the cells bound to transport proteins such as transcobalamins (Suchodolski and Steiner 2003). Although enterohepatic recirculation of cobalamin has been shown to occur in dogs (Willigan et al 1958) and humans (Herbert and Colman 1988), it has not been documented in cats. Cats lack transcobalamin 1 (Linnell et al 1979) and can, therefore, become depleted of cobalamin within a month in the presence of severe malabsorption (Hall and Simpson 2000).…”