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We have previously found reduced absorption of vitamin B12 in rats with choledochocolic fistulae. To investigate whether the reduction is caused by epithelial dysfunction or mucosal hypoplasia, choledochocolic fistulae were made in 11 rats, whereas 10 rats were sham-operated. The epithelial function was evaluated 9 days later by measuring the uptake of 57CoB12 and glucose in perfused intestinal segments and by determining the activities of 11 mucosal enzymes. Hypoplasia was investigated by performing morphometric measurements of the villus surface area and by measuring the weight, protein, and DNA in mucosal scrapings. The results suggest that choledochocolic fistulae in rats do not impair the epithelial function or cause mucosal hypoplasia. The urinary excretion of indican was increased in the fistula-operated rats, but further studies are needed to establish the significance of this observation.

Pancreatic extract (PE) reduced the uptake of rat intrinsic factor (IF)-bound 57CoB12 by perfused rat intestinal segments (p is less than 0.02) as well as by isolated rat intestinal brush borders (p is less than 0.01). The inhibition was concentration-dependent. Preincubation of the brush borders with PE recular weight of the 57CoB12-IF complex, as well as the uptake of the complex by isolated intestinal brush borders, was unchanged after prolonged preincubation with PE. PE also inhibited the uptake of glucose by perfused intestinal segments (p is less than 0.01), but the morphology and idsaccharidase activity (p is greater than 0.5) of the intestinaleptihelium was unaltered. The results indicate that the inhibition may be due to interaction between the intestinal epithelium and PE.

Determination of vitamin-B12-binding capacity and gel filtration of human pancreatic juice (HPJ) and rat pancreatic juice (RPJ) demonstrated a vitamin B12 binder different from gastric intrinsic factor (IF). The results also indicated the presence of the pancreatic B12 binding in human duodenal juice. The binder in RPJ had no significant effect on the uptake of 57CoB12 and 57CoB12 bound to rat IF by perfused rat intestinal segments (p greater than 0.5; p greater than 0.1). The binder in HPJ had no effect on the uptake of unbound 57CoB12 or 57CoB12 bound to human IF by guinea pig intestinal brush borders (p greater than 0.05; p greater than 0.1). The results indicate that the pancreatic vitamin B12 binder does not influence the intestinal uptake of vitamin B12.

The mean absorption of vitamin B12 (Schilling test) was 13.1 +/- 1.0 (% +/- S.E.M.) in 21 patients with chronic pancreatic insufficiency and 17.6 +/- 1.4 in 13 control patients (p less than 0.01). There was no correlation between pancreatic bicarbonate production after secretion stimulation and vitamin B12 absorption in the patient group (r = 0.117). Human duodenal juice reduced the uptake of 57CoB12-rat intrinsic factor (IF) by perfused rat small intestinal segments in vivo (p less than 0.01) as well as the uptake of 57CoB12-human IF by purified guinea-pig intestinal brush borders in vitro (p less than 0.01). The results confirm reduced absorption of vitamin B12 in chronic pancreatic insufficiency, but the mechanism remains uncertain.

To determine the mechanism by which pancreatic extract (PE) corrects the malabsorption of vitamin B12 in chronic pancreatic insufficiency (CPI), the following hypotheses were investigated: Firstly, PE might stimulate the absorption of vitamin B12 by changing the intestinal pH, secondly PE might stimulate the intestinal uptake of unbound vitamin B12, thirdly PE might abolish the inhibitory effect of vitamin B12 binders on the intestinal uptake of vitamin B12 bound to intrinsic factor (IF). PE had no effect on the pH in the small intestine and did not stimulate the uptake of unbound 57CoB12 by perfused rat intestinal segments. Preincubation of 57CoB12-IF with a non-IF B12-binder from human saliva (R-binder) reduced the uptake of 57CoB12 from 18.5 pg per cm intestine +/- 3.4 S.E.M. to 7.8 +/- 1.6 (p less than 0.02). PE abolished this inhibitory effect (p less than 0.05). The results indicate that PE corrects the malabsorption of vitamin B12 in CPI by an effect on non-IF B12- binders.

A simple, rapid and versatile technique for scintillation counting of double labelled fixed tissue is described. Furthermore, DNA determination can be performed on the same tissue digest.

Heavy and light microsomal fractions were subfractioned using high performance zonal rotors, and assayed for apoprotenin sensitive kallikrein-like amidolytic activity (pH 8.2). The activity profiles for the various substrates assayed show rather complex distribution pattern demonstrating kallikrein-like amidolytic activity in plasma membranes, basolateral membranes, rough endoplasmic reticulum and membranes derived from the Golgi complex.

Pancreatic extract (PE) contained small-molecular, thermo-stable as well as macro-molecular, thermo-labile factors capable of reducing the uptake of 57CoB12 bound to rat intrinsic factor by perfused rat intestinal segments (p less than 0.01 and p less than 0.01). Neither non-radioactive vitamin B12 nor non-pacreatic protein reduced the 57CoB12-uptake (p greater than 0.5 and p greater than 0.1) Crystalline trypsin and trypsinogen, but not chymotrypsin, also inhibited the uptake (p less than 0.05, p less than 0.02 and p greater than 0.05). The tryptic inhibition was abolished by soybean trypsin inhibitor (p greater than 0.05).

Human (D54Mg, GaMg) and rat (BT5C, BT4Cn) glioma cells cultured in a chemically defined medium showed reduced growth when compared to serum-supplemented medium. The BT5C cells changed from a flat epithelioid morphology to a more glia-like structure. The serum-free medium caused an aggregation of BT5C cells which spontaneously lost anchorage dependence and continued to grow in suspension as multicellular tumor spheroids. The BT4Cn and human cell lines did not show any change in morphology. Flow cytometric DNA measurements showed no change in ploidy for cells grown in serum-free medium. Cell cycle analysis revealed that the same proportion of cells were proliferating (S and G2M phase cells) in serum-free medium as compared to serum-supplemented medium. The reduced growth is probably due to increased cell cycle time.

Induction of acute Heyman nephritis in rats gave a significant increase in the urinary excretion of protein (p less than 0.001) and N-acetyl-beta-D-glucosaminidase (NAG; p less than 0.01) 14 days after injection of antibody. The isoelectric points (IP) of NAG were studied by chromatofocusing of the urine, serum and various lysosomal populations purified from kidney cortex homogenates of normal and nephritic rats. The chromatofocusing profiles for serum NAG (IP = 5.8) were totally different from the patterns found in normal and nephritic urines. The acidic IPs of NAG in normal urine (IP = 5.0) were changed into slightly more basic values in nephritic urine (IP = 5.15). Similar changes were also demonstrated in normal urine after acidification and prolonged incubation. The chromatofocusing profile obtained for NAG in the large, dense lysosomes was almost identical to the pattern observed in nephritic urine and demonstrated IPs for NAG in a slightly more basic pH area than observed for small and medium-sized lysosomes. The difference in IP in normal and nephritic urines may therefore be due to an increased autolytic degradation of NAG or excretion of the enzyme from different populations of lysosomes.