Protein-losing enteropathy and hypoalbuminemia in AIDS.

OBJECTIVE: To assess the contribution of protein-losing enteropathy to AIDS-associated hypoalbuminemia. DESIGN: Prospective assessment of patients with AIDS. SETTING: An urban county hospital (Los Angeles & University of Southern California Medical Center. USA). PATIENTS: Four groups of patients with AIDS were studied: (1) patients with normal serum albumin (> or = 3.9 g/dl) and normal bowel habits; (2) patients with normal serum albumin and diarrhea (> or = four loose or watery stools per day for > or = 2 weeks); (3) patients with hypoalbuminemia (< or = 3.0 g/dl) and normal bowel habits; and (4) patients with hypoalbuminemia and diarrhea. MAIN OUTCOME MEASURE: Fecal alpha 1-antitrypsin concentration was used as a measure of protein loss in the gut. RESULTS: Patients with hypoalbuminemia had a significantly higher mean fecal alpha 1-antitrypsin concentration than those with normal albumin (10.8 +/- 3.0 mg/g dry stool versus 2.4 +/- 0.4 mg/g dry stool; P < or = 0.001). Although mean fecal alpha 1-antitrypsin concentrations were similar in patients with and without diarrhea in the normal albumin group, patients with hypoalbuminemia and diarrhea had significantly higher levels of fecal alpha 1-antitrypsin than those with hypoalbuminemia and normal bowel habits (17.3 +/- 5.8 mg/g dry stool versus 4.6 +/- 1.0 mg/g dry stool; P = 0.009). Twelve out of 36 (33%) patients with normal albumin had elevation of fecal alpha 1-antitrypsin compared with 33 (70%) of 47 patients with hypoalbuminemia (P < or = 0.001). Linear regression analysis showed a significant negative correlation between serum albumin and fecal alpha 1-antitrypsin concentration (r = -0.38; P < or = 0.001). Fecal alpha 1-antitrypsin was significantly higher in patients with mucosal disease visualized at upper endoscopy or flexible sigmoidoscopy than in those without gross abnormalities (13.5 +/- 5.8 mg/g dry stool versus 2.4 +/- 0.7 mg/g dry stool; P = 0.005). CONCLUSION: Protein-losing enteropathy is common in patients with AIDS and may contribute to the development of hypoalbuminemia in these patients.

Fecal alpha 1-antitrypsin and hemoglobin excretion in healthy human milk-, formula-, or cow's milk-fed infants.

There is concern that whole cow's milk feedings may be associated with intestinal abnormalities in infants. We studied this issue by measuring random fecal samples for alpha 1-antitrypsin (FA1AT) and hemoglobin (FH) concentrations in 820 healthy infants up to 12 months of age. Subjects were fed either human milk, formula, or fresh whole cow's milk. Solid foods were given ad libitum. Fecal samples were also tested for occult blood with Hematest reagent tablets. None of the infants younger than 6 months of age were receiving fresh whole cow's milk. We found small but statistically significant differences in mean FA1AT between the three feeding groups (P less than .0001): human milk (n = 354) greater than formula (n = 320) greater than cow's milk (n = 146). The younger subjects fed either formula or human milk tended to have higher FA1AT concentrations than did the age-matched subjects who were not consuming solid foods (P less than or equal to .005). Daily FA1AT excretion, FA1AT concentration, and daily stool output were subsequently determined on a separate group of 40 infants 8 to 12 months of age to ascertain whether differences in total daily FA1AT excretion occur in children fed different types of milk. Total daily FA1AT excretion was similar in the three milk feeding groups. An inverse correlation between FA1AT concentration and daily stool output was also found (P less than .001). The overall rate of detectable FH in 792 stool smears was 2.1% and unrelated to type of milk feeding. Of 705 stool smears, 3.5% had positive Hematest reactions.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of assays for detecting alpha-1-protease inhibitor during purification from rat serum.

We purified the R1 alpha-1-protease inhibitor from rat serum and developed a convenient assay for its detection during purification procedures. Purification was accomplished by desalting, DEAE-Sephacel, zinc chelate, and reactive green-agarose columns. The resultant antiprotease had a molecular weight of 54,000 and inhibited elastase, chymotrypsin, and trypsin. By isoelectric focusing, five bands were produced with pI values from 4.3 to 4.7. Functional assays utilizing protease substrates imbedded in agarose plates were evaluated for the ability to distinguish the R1 alpha-1-protease inhibitor from the other serum antiproteases eluted in column chromatography fractions. This technique of screening for anti-protease activity was compared to conventional spectrophotometric methods and was found to correlate well when quantifying inhibition of elastase and chymotrypsin, but not trypsin. The presence of alpha-1-protease inhibitor was most reliably detected by testing for anti-elastase activity. Technician time and expense were saved by employing protease substrate plates to test chromatogrpahy fractions. This technique may facilitate purification of other protease inhibitors.

Alpha-1-antitrypsin concentration in human milk.

Alpha-1-antitrypsin concentration was analyzed by immunoelectrophoresis in samples of human colostrum (n = 3) and of mature milk from mothers between 2 to 52 wk postpartum (n = 39), one of whom was known to be PiMZ with a PiZZ infant. All milk samples tested contained alpha-1-antitrypsin. The three colostrum samples contained 140, 520, and 250 mg/liter. The mature milk of women who had been lactating less than 6 months had a higher concentration (7.2 +/- 3.6 mg/liter) (mean +/- SD) than in the women who had been lactating 6-12 months (4.8 +/- 1.8 mg/liter) (p less than 0.03). The milk of the woman of Pi type MZ had an alpha-1-antitrypsin concentration of 7.0 mg/liter at 7 wk postpartum and 4.1 mg/liter at 52 wk. It has been previously demonstrated that enhanced absorption of intact proteins occurs in early infancy. The presence of antiproteases in human milk provided during early infancy may serve to inhibit the absorption of intact proteases, limiting their entry into the portal circulation.

Determination of fecal alpha 1-antitrypsin concentration by radial immunodiffusion: two systems compared.

We compared Helena "QUIPlates" and Calbiochem "LC-Partigen" radial immunodiffusion systems for their ability to measure fecal concentrations of alpha 1-antitrypsin (FA1AT). Reference ranges for FA1AT concentrations in infants receiving various diets, in children, and in adults are given for each system. FA1AT values obtained with Calbiochem LC-Partigen plates averaged 30% greater than those obtained with Helena QUIPlates, but both systems distinguished between normal and high values. Studies involving variations of usual sample-handling procedures showed that storage at room temperature, repeated freezing and thawing, and long-term storage of frozen samples had no significant effect on measured FA1AT concentration. However, values obtained for lyophilized and nonlyophilized samples did not correlate well.

Infantile colic and type of milk feeding.

The prevalence of colic with respect to the type of milk feeding in the first 17 weeks of life was assessed by questioning the parents of 964 healthy infants aged 2 to 52 weeks. There was a similar prevalence of colic in infants fed human milk (20%), formula (19%), and formula-supplemented human milk (21%). Intestinal damage, determined by measuring random fecal alpha 1-antitrypsin concentrations in 206 infants aged 2 to 17 weeks and fecal hemoglobin concentrations in 200 of these, was not more likely in infants with colic at the time of study. The occurrence of adverse reactions at the time of introduction of fresh whole cow's milk into the diet of previously colicky infants was uncommon. Our results suggest that dietary protein hypersensitivity is probably not the cause of colic in most healthy young infants.