Use of hydrogen gas (H2) analysis to assess intestinal absorption. Studies in normal rats and in rats infected with the nematode, Nippostrongylus brasiliensis.

The in vitro and in vivo production of hydrogen gas (H2) from various carbohydrates or proteins has been examined in normal rats and in rats infected with the nematode Nippostrongylus brasiliensis. Normal rat fecal homogenates were capable of producing H2 in vitro from glucose, sucrose, xylose, lactulose, bovine serum albumin, or casein hydrolysate. Direct injection of glucose, sucrose, xylose, lactulose, bovine serum albumin, or casein hydrolysate into the cecum of normal rats resulted in approximately twice as much H2 production in vivo than when these same carbohydrates or proteins were administered to the normal rats by gavage. Partial small intestinal villous atrophy was produced by infecting rats with the nematode N. brasiliensis. Impaired small intestinal cell function and evidence of malabsorption in the nematode-infected rats included: (a) decreased activity of intestinal cell lactase (-43%), sucrase (-33%), and alkaline phosphatase (-46%); (b) decreased gut sac uptake of 3-O-(methyl-3H]-D-glucose (-21%) or 1-[carboxyl-14C]-aminocyclopentane-1-carboxylic acid (-28%); and (c) increased (+ 64%-561%) 14CO2 production after D-[U-14C]xylose administration. These rats produced approximately twice as much H2 after gavage administration of glucose, sucrose, xylose, bovine serum albumin, or casein hydrolysate compared with normal rats. The present study suggests that H2 analysis may be useful in the evaluation of small intestinal malabsorption states in rats.

Intestinal uptake of macromolecules. VI. Uptake of protein antigen in vivo in normal rats and in rats infected with Nippostrongylus brasiliensis or subjected to mild systemic anaphylaxis.

Adult Sprague-Dawley rats weighing approximately g were fed bovine serum albumin and sodium bicarbonate by gavage. Serum was obtained at intervals after feeding and tested for immunoreactive bovine serum albumin by radioimmunoassay. Nanogram amounts of immunoreactive bovine serum albumin were detected in serum; peak values were obtained after 4 and 6 hr. The influence of intestinal inflammation on protein uptake was examined in two model systems. Infection of rats with Nippostrongylus brasiliensis was accompanied by partial villous atrophy in the intestinal segments harboring adult worms and mild systemic anaphylaxis in the rat was accompanied by increased intestinal vascular and mucosal permeability. Enhanced uptake of BSA was observed before and shortly after self-cure of infection and during mild systemic anaphylaxis. The molecular size of immunoreactive bovine serum albumin approximated that of the administered bovine serum albumin; no small fragments of bovine serum albumin bearing antigenic determinants were detected.

Antigenicity of infant formulas: role of immature intestine on protein permeability.

Preliminary studies of 25 infants fed casein hydrolysate, soy-based or milk-based formulas were undertaken to determine the importance of age with respect to the relative antigenicity of formula proteins. Infants fed casein hydrolysate for the first three months had lower antibody titers (hemagglutinins) to subsequent milk-based or soy-based proteins than those given these formulas since birth. The clinical implications with regard to atopy and gastrointestinal protein intolerance are discussed. Soy protein is at least as antigenic as milk protein and should be used with caution in prophylaxis against possible dietary antigen/antibody-related disease.

Alpha1-fetoprotein in neonatal hepatobiliary disease.

It has been suggested that the quantitative estimation of serum alpha-1-fetoprotein may help in distinguishing the neonatal hepatitis syndrome from biliary atresia. We measured the serum AFP concentration in 52 neonates and infants with various hepatobiliary disorders, including neonatal hepatitis syndrome (group I), biliary atresia (group II), and other hepatopathies such as choledochal cyst (group III). The mean serum AFP concentration in patients with neonatal hepatitis was significantly greater than the mean concentration in the other two groups. There was no significant difference between the mean serum AFP concentrations in patients with biliary atresia and in group III patients. Patient age was noted to be an important factor: Serum AFP levels greater than 35 microgram/ml in infants one to four months of age suggpst the diagnosis of neonatal hepatitis syndrome. Serum AFP levels below 10 microgram/ml in infants less than four months of age suggest the diagnosis of biliary atresia or hepatopathies other than neonatal hepatitis. However, the variable and significant overlapping of serum AFP values between 10 and 35 microgram/ml limit the diagnostic value of this test.