Veda N. Nichols

Human lactoferrin supplementation of infant formulas increases thymidine incorporation into the DNA of rat crypt cells

Lactoferrin has been identified as the factor in human colostrum that accounts for the increased incorporation of thymidine into DNA in a rat crypt enterocyte bioassay. Commercially available infant formulas used in the refeeding of infants who have severe dietary intolerance associated with mucosal atrophy were tested in this bioassay. In contrast to human milk, no stimulation was observed with these formulas in the assay. All formulas inhibited basal thymidine incorporation. The degree of inhibition of the basal assay progressed from 14% with cows-milk formula to 30% with soy-based formulas to 45% with hydrolyzed casein formulas. When the formulas were supplemented with lactoferrin to match the level of that in human milk, the result was a 35% relative increase in thymidine incorporation into DNA. The quantitative level of response was primarily influenced by the baseline inhibitions associated with the specific formulas. The most profound effect was observed with the hydrolyzed casein formula, when lactoferrin supplementation reversed the baseline inhibition but did not result in a response greater than that seen in control basal bioassays. The supplementation of infant formulas with lactoferrin improved the thymidine incorporation in rat crypt enterocytes; a response equivalent to that of human milk, however, would require a redesign of other formula components to reduce basal inhibition.

Mosaic expression of brush-border enzymes in infants with chronic diarrhea and malnutrition

The chronic diarrhea observed in young malnourished infants that is sensitive to dietary glucose and other carbohydrates is associated with variable degrees of patchy mucosal villous atrophy. To explore intrinsic mucosal function in the pathogenesis of this alimentary intolerance, we have conducted an immunohistologic investigation of brush-border enzyme proteins of clinically obtained, mucosal biopsy samples. We used a group of monoclonal antibodies against human brush-border aminopeptidase, sucrase/isomaltase (SI), maltase, and lacase enzyme proteins. SI was strongly and uniformly exssed in crypts and villi of 11 of the 14 subjects; in 3 ects, however, SI was expressed in a mosaic pattern. Maltase and lactase were occasionally absent, but more commonly were expressed in a mosaic distribution. The mosaic expression of brush-border enzyme proteins has been reported in congenital enzyme deficiencies associated with normal intestinal histology. We report the mosaic expression of brush-border enzyme proteins as a functional alteration associated with a pathological lesion of the mucosa in infants with chronic diarrhea. Our observation challenges the existing concept of ontogenic regulation of brush-border enzyme activity.

Contribution of villous atrophy to reduced intestinal maltase in infants with malnutrition.

BACKGROUND It has been known for many years that small intestinal maltase activities are reduced in malnourished infants and in other patients with villous atrophy. The recent availability of human maltase-glucoamylase cDNA provides the opportunity to test the hypothesis that villous atrophy accounts for the reduced maltase enzyme activity in malnourished infants. METHODS Mucosal biopsy specimens obtained for clinical evaluation of malnourished infants with poor responses to refeeding were examined by quantitative methods for enzyme activity and mRNA levels. RESULTS Maltase activity and maltase-glucoamylase mRNA were reduced (approximately 45% of normal). When maltase-glucoamylase message was normalized to villin message, a structural protein expressed only in enterocytes, a preservation of maltase messages in surviving enterocytes was documented. The luminal glucose transporter-villin message was also preserved. CONCLUSIONS The loss of maltase-glucoamylase message paralleled the reduction in villin message and degree of villous atrophy. The reduced maltase-glucoamylase message also paralleled sucrase-isomaltase message, previously found to be decreased in proportion to villous atrophy of malnourished infants. The data directly demonstrate, for the first time, that the terminal steps of starch 1-4 starch digestion and sucrase-isomaltase 1-6 starch digestion are decreased in malnourished infants, secondary to villous atrophy. These data in prior and present reports suggest that mechanisms underlying the chronic villous atrophy of malnutrition should be a priority for investigations in malnourished infants with slower than expected weight gain during refeeding.

Pathogenesis of small-intestinal mucosal lesions in chronic diarrhea of infancy: II. An electron microscopic study.

Our electron microscopic study of biopsies taken from 10 infants with protracted diarrhea was conducted in an effort to determine the pathogenesis of the disorder. In this article, the ultrastructure of the jejunal mucosa of the infants is described in relation to overlying or adherent bacteria of unidentified type. In addition to the known changes on the enterocyte surface caused by adherent bacteria (cupping and effacement), other cytopathic changes, not previously reported, are documented. Included are widespread loss of enterocytes, including intraepithelial lymphocytes, into the bowel lumen; cyto-pathological changes within the enterocytes: and marked thickening of the basal laminae of the enterocytes and the endothelium of lamina propria blood vessels. In addition. we noted deposition of collagen fibrils in the lamina propria below the basal laminae, active phagolysis within macrophages, and lack of cisternal material (immunoglobulin) in the plasma-cell cytoplasm. Although these changes are nonspecific, they may be related in part to the presence of the nonadhering and adhering bacteria, and their identification may further our understanding of the “sick mucosa” that occurs in chronic diarrhea of infancy.

Acquired monosaccharide intolerance in infants

To determine the frequency with which acquired monosaccharide intolerance (AMI) occurs in infants <3 months of age, we performed a prospective descriptive study of infants admitted to the hospital for diarrhea. We searched for differences between the characteristics and causes of AMI in these infants and those of a cohort of similar-aged infants admitted with acute diarrhea (AD). Five hundred fifty-five infants <3 months of age admitted with diarrhea were enrolled. Nine percent of those infants had AMI, 40% had other forms of chronic diarrhea, and 51% had AD. The mean age at hospital admission was 32 days for the infants with AMI and 44 days for the infants with AD. The mean weight loss of AMI infants was 0.3 g/day since birth, and the mean weight gain was 14.3 g/day for AD infants. The mean dehydration by difference in weights at admission and 48 h postadmission was 5% for AMI and 3% for AD infants. Bacterial and viral causes of the diarrhea were similar. At admission to the hospital, infants in whom AMI subsequently developed were younger, more malnourished, had more prolonged diarrhea, and were more dehydrated than the AD infants. Malnutrition stands out as a significant antecedent factor that contributes to the development of AMI.

Comparison of acquired monosaccharide intolerance and acute diarrheal syndrome.

In a retrospective study, 9% of the admissions to Ben Taub General Hospital for diarrhea were found to have acquired monosaccharide intolerance (AMI). The course of AMI was compared with that of acute diarrheal syndrome (ADS). The patients with AMI were younger at the time of admission, and, although the mean birthweight and percent of prematurity were approximately the same in the two groups, the AMI patients were found to be malnourished (p less than 0.02). Data suggest that the nutritional insult had occurred between birth and admission, and that malnutrition was a contributing factor in the development of AMI.

Malnutrition in infants with acute diarrheal syndrome.

The data from the charts of 109 infants who were younger than 9 months of age and who had been hospitalized with acute diarrheal syndrome in 1978 were compared with data from the charts of 108 healthy infants of the same age range with the same sex and ethnic distributions who were attending well-child clinics serving the same geographic area during the same year. In a comparison of weight percentiles, 45.3% of the acute diarrheal syndrome patients and 11.3% of the well children were below the 10th percentile. When height percentiles were compared, 41.8% of the acute diarrheal syndrome patients and 15.3% of the well children were below the 10th percentile. The data indicate that malnutrition was a characteristic of infants with acute diarrheal syndrome who required hospitalization.

THE RELATIONSHIP OF ROTAVIRUS TO ACQUIRED MONOSACCHARIDE INTROLERANCE (AMI) IN YOUNG INFANTS

A prospective study of diarrhea associated with AMI is being conducted in Houston, TX. Infants (n=459) less than 3 mo of age have been enrolled in the study (10-1-80 to 10-1-83). A stool specimen was collected from each patient and tested for rotavirus by Rotazyme®. Forty-six percent of the infants had acute diarrheal syndrome (ADS),(diarrhea < 14 days duration), 45% had chronic diarrhea (CD), (diarrhea > 14 days duration), and 9% had AMI, a form of chronic diarrhea which occurs after feeding any dietary carbohydrate. Mean age at admission (days) was 37 for ADS, 42 for CD, and 31 for AMI. The average duration of acute diarrheal symptoms prior to admission was 3.3 days for ADS, 5.9 for CD, and 5.1 for AMI infants. The weight change (g/d) from birth was 11.9 for ADS, 7.1 for CD, and -1.7 for AMI infants. Rotavirus was detected in the stools of 15% of ADS, 10% of CD, and 30% of the AMI infants. These findings suggest that rotavirus may be associated with the development of monosaccharide intolerance. A chronic state of malnutrition, however, may play a primary role in the development of monosaccharide intolerance.

Dietary origin of retained H+ in infants with acquired monosaccharide intolerance.

Net external acid balance was studied in 12 malnourished infants with chronic diarrhea (some of whom had acquired monosaccharide intolerance). When the infants achieved an adequate energy intake from a formula that contained either glucose or glucose polymers, seven developed metabolic acidosis and Five remained free of acidosis. During the study, the acidotic infants produced a significant excess of acid (3.7 ± 2 vs. 0.5 ± 2 mEq/kg/day, p < 0.005). The amount they excreted in urine (2.9 ± 2 mEq/kg/day), however, was similar to that excreted by nonacidotic infants (2.7 ± 2 mEq/kg/day) and indicated renal inability to reduce the excess acid load. The net effect was hydrogen ion (H + ) retention ( + 0.8 ± 0.8 vs. −2.2 ± 0.8 mEq/kg/day, p < 0.001). Good correlation existed between the net acid balance and the acid-base measurement in the blood. We speculate that (a) the increased acid load was a consequence of colonic bacterial production of volatile fatty acids from carbohydrate malabsorbed from the small bowel and (b) the renal incapacity to excrete H + probably was secondary to potassium and phosphate depletion.

Epigenetic Suppression of Maltase Message and Activity in Malnourished Infants with Chronic Diarrhea ♦ 594

Epigenetic Suppression of Maltase Message and Activity in Malnourished Infants with Chronic Diarrhea ♦ 594