Comparative sensitivity of eight- and 24-hour bile acid breath tests and Schilling test in ileopathies.

The conventional eight-hour bile acid breath test ("acute measurements"), was compared with a modified, extended, 24-hour breath test ("ratio measurements") and the Schilling test to assess relative sensitivity in detecting ileal dysfunction. Sixty-four patients with ileopathies were studied. The presence or absence of bile acid malabsorption was documented by fecal excretion studies of bile acid labels. The sensitivity of the "acute measurements" in the breath test was not significantly different from that of the "ratio measurements" in the ileopathies, regardless of whether or not bile acid malabsorption was present. The "acute measurements" were positive in 49 (77%), the "ratio measurements" in 54 (84%) and the Schilling test in 49 (77%) of the patients. In about 30%, bile acid breath test and Schilling test were not positive in the same patient. A combination of "acute measurements" (breath test) and Schilling test increased the percentage of cases with at least one positive test to 91%. The results of the study show: 1. The sensitivity of the bile acid breath test does not increase if 14CO2 measurements are carried out beyond eight hours. 2. Although the breath test and Schilling test are of similar sensitivity in ileopathies, they are frequently not positive in the same patient. Therefore, it would be clinically useful to combine both tests in order to increase the likelihood of diagnosing ileal dysfunction.

Evidence for two different modes of tripeptide disappearance in human intestine. Uptake by peptide carrier systems and hydrolysis by peptide hydrolases.

The intestinal fate of two tripeptides (triglycine and trileucine), which differ markedly in solubility and molecular weight, have been investigated by jejunal perfusion in healthy human volunteers. Rates of glycine or leucine uptake from test solutions containing triglycine or trileucine were greater than from test solutions containing corresponding amounts of free glycine or free leucine, respectively. The rate of glycine uptake from a 100 mM triglycine solution was greater than that from a 150 mM diglycine solution. At each infused load of triglycine (e.g., 1,000 mumol/min) the rates (micromoles/minutes per 30 cm) of either triglycine disappearance (810 +/- 40) or glycine absorption (2,208 +/- 122) were markedly greater than the luminal accumulation rates of either diglycine (56 +/- 10) or free glycine (110 +/- 18). The luminal accumulation rate of free leucine during infusion of a 5 mM trileucine solution was over threefold greater than that of free glycine during the infusion of a 5 mM triglycine solution. Luminal fluid exhibited no hydrolytic activity against triglycine, but contained some activity against trileucine. Saturation of free amino acid carrier system with a large load of leucine did not affect glycine absorption rate from a triglycine test solution, but isoleucine markedly inhibited the uptake from a trileucine solution. When the carrier system for dipeptides was saturated with a large amount of glycylleucine, the disappearance rate of triglycine was considerably reduced while that of trileucine remained unaffected. After addition of glycylleucine to tripeptide solutions, there was a minimal increase in the luminal accumulation of diglycine, while dileucine accumulation was incresed by 62-fold.

Role of insulin and glucose in the induction of hypoaminoacidemia in man: studies in normal, juvenile diabetic, and insuloma patients.

It is generally assumed, but not established, that the lowering of plasma free amino acid levels following glucose intake is entirely mediated by stimulated insulin secretion. This problem was investigated in groups of healthy volunteer subjects, juvenile diabetics, and insuloma patients. The plasma concentrations of 15 individual free amino acids, glucose, and insulin or C-peptide were determined before and at intervals after either oral glucose (75 Gm.) or intravenous glucose (0.25 Gm. per kilogram of body weight) or tolbutamide (1 Gm.). Glucose lowered plasma amino acid levels in both situations of stimulated (healthy volunteer subjects) and absent (diabetic) insulin secretion. The lack of insulin response in juvenile diabetics was evident by the lack of any significant increase in C-peptide levels following glucose ingestion. Nevertheless, despite markedly greater plasma glucose levels, hypoaminoacidemia was less severe in diabetics than in normal volunteer subjects. In comparison to healthy volunteer subjects who showed significant decreases in concentrations of 14 of 15 examined amino acids by glucose, the diabetic individuals exhibited significant decreases in concentration of 8 amino acids (leucine, isoleucine, valine, tyrosine, phenylalanine, methionine, citrulline, and arginine). In face of a massively greater insulin response in an insuloma patient (greater than 1,000 muU per milliliter), the decreases in the levels of individual free amino acids following glucose were within the range of values obtained in the normal volunteer subjects. The stimulation of insulin secretion with tolbutamide also lowered the concentrations of free amino acids in plasma. However, one importnat difference distinguished the effect of tolbutamide from that of glucose. Within a few minutes after the injection of tolbutamide, there was a marked and persistent fall in alanine levels, while during the entire course of the glucose tolerance test there were no significant changes in the level of this amino acid, suggesting a difference in the mechanism of hypoaminoacidemia induced by endogenous insulin in the presence or absence of exogenous glucose. Despite a markedly greater insulin response to tolbutamide in the insuloma patient (greater than 1,500 muU per milliliter), the decreases in plasma glucose and free amino acid levels fell within the range of values obtained in normal volunteer subjects. In conclusion, the exogenous glucose per se lowers the levels of free amino acids in plasma. This effect is enhanced by insulin.

Occurrence of zoogloea colonies and protozoans at different stages of sewage purification.

The presence of fingered branch-bearing Zoogloea has been noted on a number of occasions in the Baroda Sewage Disposal Works. Samples of raw sewage, the effluent from the continuous flow settling basin, the raw sludge, the floating scum in the settling basin, the final secondary digested sludge, and the supernatant liquid from the secondary digester were kept without any disturbance in 1-liter Pyrex glass beakers, which were loosely covered with petri dishes. Scum was formed on the surface within 48 hr in all the samples, and fingered Zoogloea colonies resembling the pure culture of Zoogloea ramigera reported by Crabtree et al. (5) were found in all except the final secondary digested sludge and the supernatant liquid from the secondary digester. It is not known whether the Zoogloea colonies discovered in the above cases are the same as or different from the typical Zoogloea ramigera of activated sludge, and whether they are slime-forming or flocculent types of bacteria. In any case, they seem to be different in their ecological status and in the nature of the accompanying protozoans from the typical Zoogloea ramigera. The reasons for the absence of zoogloeas in two of the samples are unknown.