Glucoamylase and disaccharidase activities in normal subjects and in patients with mucosal injury of the small intestine

Genetic and acquired sucrase-isomaltase deficiency: A clinical review

Genetic sucrase-isomaltase deficiency (GSID) is an inherited deficiency in the ability to digest sucrose and potentially starch due to mutations in the sucrase-isomaltase (SI) gene. Congenital sucrase-isomaltase deficiency is historically considered to be a rare condition affecting infants with chronic diarrhea as exposure to dietary sucrose begins. Growing evidence suggests that individuals with SI variants may present later in life, with symptoms overlapping with those of irritable bowel syndrome. The presence of SI genetic variants may, either alone or in combination, affect enzyme activity and lead to symptoms of different severity. As such, a more appropriate term for this inherited condition is GSID, with a recognition of a spectrum of severity and onset of presentation. Currently, disaccharidase assay on duodenal mucosal tissue homogenates is the gold standard in diagnosing SI deficiency. A deficiency in the SI enzyme can be present at birth (genetic) or acquired later, often in association with damage to the enteric brush-border membrane. Other noninvasive diagnostic alternatives such as sucrose breath tests may be useful but require further validation. Management of GSID is based on sucrose and potentially starch restriction tailored to the individual patients' tolerance and symptoms. As this approach may be challenging, additional treatment with commercially available sacrosidase is available. However, some patients may require continued starch restriction. Further research is needed to clarify the true prevalence of SI deficiency, the pathobiology of single SI heterozygous mutations, and to define optimal diagnostic and treatment algorithms in the pediatric population.

Microbial glucoamylases: structural and functional properties and biotechnological uses

Glucoamylases (GAs) are one of the principal groups of enzymes involved in starch hydrolysis and belong to the glycosylhydrolase family. They are classified as exo-amylases due to their ability to hydrolyze α-1,4 glycosidic bonds from the non-reducing end of starch, maltooligosaccharides, and related substrates, releasing β-D-glucose. Structurally, GAs possess a characteristic catalytic domain (CD) with an (α/α)6 fold and exhibit five conserved regions within this domain. The CD may or may not be linked to a non-catalytic domain with variable functions depending on its origin. GAs are versatile enzymes with diverse applications in food, biofuel, bioplastic and other chemical industries. Although fungal GAs are commonly employed for these purposes, they have limitations such as their low thermostability and an acidic pH requirement. Alternatively, GAs derived from prokaryotic organisms are a good option to save costs as they exhibit greater thermostability compared to fungal GAs. Moreover, a group of cold-adapted GAs from psychrophilic organisms demonstrates intriguing properties that make them suitable for application in various industries. This review provides a comprehensive overview of the structural and sequential properties as well as biotechnological applications of GAs in different industrial processes.

Growth and Clinical Variables in Nitrogen-Restricted Piglets Fed an Adjusted Essential Amino Acid Mix: Effects of Partially Intact Protein-Based Diets

Background

Current recommendations for protein levels in infant formula are intended to ensure that growth matches or exceeds growth of breastfed infants, but may provide a surplus of amino acids (AAs). Recent infant studies with AA-based formulas support specific adjustment of the essential amino acid (EAA) composition allowing for potential lowering of total protein levels. With the use of a combination of intact protein and free EAAs, we designed a formula that meets these adjusted EAA requirements for infants.

Objective

Our objective was to test whether this adjusted formula is safe and supports growth in a protein-restricted piglet model, and whether it shows better growth than an isonitrogenous formula based on free AAs.

Methods

Term piglets (Landrace × Yorkshire × Duroc, n = 72) were fed 1 of 4 isoenergetic formulas containing 70% intact protein and 30% of an EAA mixture or a complete AA-based control for 20 d: standard formula (ST-100), ST-100 with 25% reduction in proteinaceous nitrogen (ST-75), ST-75 with an adjusted EAA composition (O-75), or a diet as O-75, given as a complete AA-based diet (O-75AA).

Results

After an initial adaptation period, ST-75 and O-75 pigs showed similar growth rates, both lower than ST-100 pigs (∼25 compared with 31 g · kg-1 · d-1, respectively). The O-75AA pigs showed further reduced growth rate (15 g · kg-1 · d-1) and fat proportion (both P < 0.05, relative to O-75).

Conclusions

Formula based partly on intact protein is superior to AA-based formula in this experimental setting. The 25% lower, but EAA-adjusted, partially intact protein-based formula resulted in similar weight gain with a concomitant increased AA catabolism, compared with the standard 25% lower standard formula in artificially reared, protein-restricted piglets. Further studies should investigate if and how the specific EAA adjustments that allow for lowering of total protein levels will affect growth and body composition development in formula-fed infants.

Starch Malabsorption in Infants

Based on the developmental physiology of pancreatic amylase production, starch digestion in young infants was anticipated to be compromised whenever compared with that in older infants and toddlers. This appears to be the case, but with great variability among infants to digest starch. Evidence points to the importance of maltase-glucoamylase in young infants and its effect on starch digestion. These observations have critical importance for recommendations regarding the feeding of starch-containing foods to young infants.

Disaccharidase activity in children undergoing esophagogastroduodenoscopy: A systematic review

AIM: To investigate the utility of intestinal disaccharide analysis during esophagogastroduodenoscopy (EGD) in children, we performed a systematic review of studies examining disaccharide activity.

METHODS: All full-length articles published in English during 1966-2014 were included if: (1) participants had small intestinal biopsy evaluation of disaccharide activity; (2) levels of lactase, sucrase, maltase or palatinase were reported; and (3) age of participants was under 18 years.

RESULTS: Thirty articles examining 34753 disaccharide assays fulfilled the specific search, inclusion, and exclusion criteria. All of the studies were observational in design and 57% (17) were prospective. Sixteen studies were conducted in the United States and 9 European studies were identified. The biggest study enrolled about 30, 314 procedures and 13 studies investigated fewer than 50 procedures. Eleven studies examined Caucasian subjects, 3 studies examined Asian subjects, and 6 examined African subjects. Only one Hispanic subject was included. In studies reporting disaccharide deficiency, the overall proportion of lactase deficiency was 39.2%, sucrase deficiency was 9.0%, maltase deficiency was 12.6% and palatinase deficiency was 9.1%. The prevalence of duodenal inflammatory changes ranged from 6% to 24% for non-specific histological lesions (e.g., duodenitis). Sixteen studies examined the association of histologic findings with disaccharide activities, and 12 studies reported an inverse association between degree of histologic inflammation and disaccharide levels.

CONCLUSION: We reviewed 30 studies including 34753 biopsy specimens with disaccharide analysis from children undergoing EGD. Our findings advocate a large study is to further illuminate the importance of EGD with disaccharide analysis in children.

Intestinal disaccharidase activity in patients with autism: effect of age, gender, and intestinal inflammation

Intestinal disaccharidase activities were measured in 199 individuals with autism to determine the frequency of enzyme deficiency. All patients had duodenal biopsies that were evaluated morphologically and assayed for lactase, sucrase, and maltase activity. Frequency of lactase deficiency was 58% in autistic children ≤ 5 years old and 65% in older patients. As would be expected, patients with autism at age 5 > years demonstrated significant decline in lactase activity (24%, p = .02) in comparison with ≤ 5 years old autistic patients. Boys ≤ 5 years old with autism had 1.7 fold lower lactase activity than girls with autism (p = .02). Only 6% of autistic patients had intestinal inflammation. Lactase deficiency not associated with intestinal inflammation or injury is common in autistic children and may contribute to abdominal discomfort, pain and observed aberrant behavior. Most autistic children with lactose intolerance are not identified by clinical history.

Glucoamylase activity in infants and children: normal values and relationship to symptoms and histological findings

BACKGROUND

Starch digestion is dependent on a combination of pancreatic and salivary amylase and the intestinal brush border enzymes glucoamylase and sucrase-isomaltase. Glucoamylase splits successive glucose molecules from the nonreducing end of starch molecules and is particularly important in infants who are relatively deficient in pancreatic amylase.

METHODS

The authors measured glucoamylase activity in endoscopic mucosal biopsies submitted for measurement of disaccharidase activity from 214 patients aged 1 month to 20 years. Glucoamylase activity was measured using glucose polymers (polycose) as the substrate. The authors also related enzyme activity to histologic appearance and clinical indication for endoscopy.

RESULTS

The most common reasons for biopsy were abdominal pain, gastroesophageal reflux, and vomiting. Disaccharidase activity by age was similar to previous reports. Glucoamylase activity did not differ with age, but was 2 to 3 times the activity reported previously. Glucoamylase activity was significantly depressed in children with the most severe histologic abnormalities. Normal glucoamylase activity (+/-2 SD) was 80.6 +/- 54.8 micromoles of glucose produced per minute per gram of protein.

CONCLUSIONS

Glucoamylase activity is 2 to 3 times higher when glucose polymers are used as substrate than when glycogen is used. Severe mucosal disease is associated with reduced glucoamylase activity. Quantitation of glucoamylase activity with glucose polymers is more appropriate in evaluating children since these polymers are commonly used as carbohydrate source in the diet.

Disaccharidase activities in dyspeptic children: biochemical and molecular investigations of maltase-glucoamylase activity

BACKGROUND

Maltase-glucoamylase enzyme plays an important role in starch digestion. Glucoamylase deficiency is reported to cause chronic diarrhea in infants, but its role in dyspeptic children is unknown.

METHODS

Glucoamylase and other disaccharidase specific activities were assayed from duodenal biopsy specimens in 44 children aged 0.5-18 years (mean, 10 +/- 5 years) undergoing endoscopy to evaluate dyspeptic symptoms. All subjects had normal duodenal histology. Intestinal organ culture was used to evaluate synthesis and processing of maltase-glucoamylase. Sequencing of the maltase-glucoamylase coding region was performed in subjects with low activity or variation of isoform in organ culture.

RESULTS

Twenty-two of the dyspeptic children had one or more disaccharidases with low specific activity. Twelve subjects (28%) had low activity of glucoamylase. Eight subjects had low activities of glucoamylase, sucrase, and lactase. Low glucoamylase activity was not correlated with the isoform phenotype of maltase-glucoamylase as described by metabolic labeling and sodium dodecyl sulfate electrophoresis. Novel nucleotide changes were not detected in one subject with low glucoamylase activity or in two subjects with variant isoforms of maltase-glucoamylase peptides.

CONCLUSION

Twelve of 44 dyspeptic children had low specific activity of duodenal maltase-glucoamylase. Eight of these children had low specific activity of all measured disaccharidases.

Ontogeny of insulin-like growth factor 1 in a rabbit model of growth retardation

Many cases of intrauterine growth retardation (IUGR) result from placental insufficiency, but the molecular signals accompanying this event are unknown. Insulin-like growth factor 1 (IGF-1) is a potent mitogen for fetal tissues and is lowered in the serum of human infants with IUGR. The rabbit provides an optimal model for the study of IUGR based on fetal position. To determine if IGF-1 expression is altered in the growth-retarded fetus, this naturally occurring rabbit model of IUGR was used. Four fetal rabbit pairs were harvested on Days 21, 23, 25, 27, 29, and 31 of their normal 31-day gestation; they were identified based on uterine position as normal or growth retarded. Fetal weight was recorded and the serum, amniotic fluid, liver, kidney, and small intestine (SI) were collected. The SI was divided into three equal segments: proximal, middle, and distal. Reverse transcription polymerase chain reaction (RT-PCR) was used to measure IGF-1/beta-actin mRNA densitometric band ratios in all tissues. Radioimmunoassay (RIA) was used to measure IGF-1 protein levels in the serum and amniotic fluid. Statistical analysis was performed using ANOVA and the paired Student's t test. Weights were decreased in fetuses with IUGR at all time points (P < 0.05), further validating this rabbit model in the study of IUGR. Liver, proximal, and distal SI IGF-1 mRNA decreased during late gestation (P < 0.01). Kidney IGF-1 mRNA increased throughout late gestation (P < 0.01). Compared with their normal counterparts, fetuses with IUGR had a trend toward decreased IGF-1 mRNA in the kidney, liver, and SI at all time points, reaching significance in the liver on Day 27 (P = 0.002). Serum IGF-1 decreased throughout gestation in all fetuses (P < 0.05). Compared with normal fetuses, fetuses with IUGR had lower serum IGF-1 at all time points, reaching significance at Day 27 (P = 0.02). Amniotic fluid IGF-1 was lower in fetuses with IUGR than in normal fetuses, though not quite reaching significance. Compared with normal fetuses, growth-retarded fetal rabbits trend toward depressed liver, kidney, and intestinal expression of IGF-1 mRNA and lower serum and amniotic fluid IGF-1 protein. Serum IGF-1 levels correlate with fetal weight change. Further studies and potential manipulation of fetal IGF-1 are warranted to investigate potential prenatal intervention in the treatment of IUGR.

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.

Disaccharidase activities in children: normal values and comparison based on symptoms and histologic changes

BACKGROUND

The relationship between symptoms, intestinal mucosal histology, and disaccharidase activities is not well defined. An analysis of disaccharidase activities was performed in children grouped by age, symptoms, and intestinal mucosal histology and normal values established.

METHODS

Disaccharidase activities and histology of 246 endoscopically obtained duodenal biopsies in 232 patients (121 girls; age range, 0.08-17 years; mean, 5.9 years) in a 3-year period were reviewed. Patients were divided into two groups based on absence (group 1; n = 142) or presence (group 2; n = 90) of diarrhea and were subdivided by age into, less than 24 months of age and 24 months of age or more. Histologic changes within groups were classified as (A) normal, (B) mild, or (C) moderate to severe based on villus height abnormalities. A questionnaire was sent to 34 patients with hypolactasia to assess the efficacy of lactose avoidance and/or lactase supplementation.

RESULTS

All group 1 patients had normal findings in analysis of mucosal specimens, and their disaccharidase activities showed normal values because they had no diarrhea. The geometric means (95% confidence interval) in children aged less than 24 months are (in micromoles of substrate hydrolyzed per minute at 37 degrees C per gram protein) (units [U]) lactase, 36.7 (13.4-100.4); maltase, 178.5 (88.9-356.3); palatinase, 12.7 (3.8-41.5); and sucrase 60.0 (24.0-148.1). In children 24 months of age or more, the values are 23.2 (3.9-108.1), 167.6 (78.8-355.9), 12.7 (4.9-32.9), and 51.0 (20.5-126.0), respectively. Only lactase activity decreased with age (p < 0.05). No differences in disaccharidase activities were noted in patients with and without diarrhea if the mucosal histology was normal (group 1A vs. 2A). In patients with diarrhea, values were commensurate with the degree of mucosal injury, especially in the older group. Twenty-two of 27 patients (81%) who responded to the questionnaire had benefited from lactase supplementation and/or lactose avoidance.

CONCLUSIONS

We have established normal values for disaccharidase activities in the pediatric population. Although the disaccharidase activities correlate more with degree of intestinal mucosal injury than with symptoms, their activities are difficult to predict accurately based on these criteria. If required, disaccharidase activities should be measured biochemically.

Impact of Yersinia enterocolitica enteritis on disaccharidase activity and small intestinal morphology in colostrum-deprived newborn piglets

The effect of enteritis on the development of the small intestine was examined in newborn, colostrum-deprived piglets infected with a human isolate of Y. enterocolitica (serotype 0:3, biotype 4) soon after birth. The piglets were killed 3 days (n = 6) or 5 days (n = 8) after infection, or antibiotic therapy was commenced on day 5 and the animals killed on day 14 (n = 5). Compared with the non-infected controls, infected animals had reduced mucosal lactase and sucrase, but not maltase activity, while after antibiotic therapy, previously infected piglets had a lower lactase and a higher maltase and sucrase activity. Lactase activity was significantly reduced in the duodenum and jejunum, and mean values were lower in the ileum, but the difference did not reach significance; maltase activity was greater at all ages from the distal jejunum to the mid-ileum; sucrase activity was reduced in all segments up to day 5 but after antibiotic therapy was increased in the jejunum and appeared early in the ileum. Enzyme profiles were more mature along the crypt-villus axis in some segments of the intestine in previously infected piglets. Sodium-potassium-ATPase activity was unchanged. There was a reduced villus height:crypt depth ratio, crypt hyperplasia and increased crypt cell proliferation. Morphological maturation, indicated by loss of vacuoles and location of the nucleus at the base of the enterocyte, proceeded distally from the duodenum to ileum from 3 to 14 days of age when only the ileum remained immature. In infected piglets, there was reduced vacuolation and earlier location of the nucleus at the base of the cell in the distal intestine. Accelerated maturity of specific disaccharidases and enterocyte morphology in infected piglets appears to be due to physical damage to the mucosa resulting in faster proliferation of crypt cells and migration of enterocytes. It is suggested that this may reduce macromolecular internalisation and impair the ability to utilise dietary carbohydrate and may have long-term effects on growth and immunological responses of the gut.

High-calorie, rice-derived, short-chain, glucose polymer-based oral rehydration solution in acute watery diarrhea

In this study, we have compared the effects of the World Health Organization oral rehydration solution (WHO ORS) and an ORS containing short polymers of glucose (Amylyte ORS) at a high caloric density (five times) and comparable osmolality, on stool output, duration of diarrhea, weight gain and fluid and electrolyte balance, in randomized, open-labeled, controlled clinical trials in five centers. A total of 198 male children (4 months to 10 years) with acute diarrhea ( <72 h after onset) were assigned by random allocation to either WHO ORS or Amylyte ORS at five centers in Asia. Children were stratified according to grade of dehydration (mild, moderate or severe) and the initial purging rates during the first 6 h (low ( < 2 ml/kg/h), moderate (2-5 ml/kg/h) and high ( > 5 ml/kg/h) purgers). The clinical characteristics of the children in the two treatment groups were comparable. Amylyte ORS reduced stool volumes significantly in children with severe dehydration (285.4 +/- 74.2 versus 75.5 +/- 20.0 ml/kg; p < 0.05) and in children with a high initial purging rate (200.3 +/- 42.8 versus 130.5 +/- 9.1 ml/kg; p < 0.05). This was accompanied by a significant (276.4 +/- 14.6 versus 227.6 +/- 11.8 ml/kg; p < 0.01) reduction in ORS requirements in the Amylyte ORS treated group, the effect being greatest in children with severe dehydration (491.5 +/- 108.5 versus 155.7 +/- 27.3 ml/kg; p < 0.01) or high initial purging rates (394.2 +/- 66.2 versus 316.8 +/- 34.8 ml/kg; p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Controversies in the composition of infant formulas

Available infant formulas contain a vast assortment of carbohydrate, protein, and fat sources in an effort to emulate the composition of human milk. Although infants receiving commercial formulas thrive, physicians should be cognizant of differences in formula composition and the research that has resulted in the differences. Such awareness permits rational and scientific recommendations both in prescription of formulas and in direction of research on the optimal formula composition for infants.

Is rice based oral rehydration therapy effective in young infants?

Rice based oral rehydration therapy (ORT) solutions have been shown to be superior to glucose oral rehydration salts (World Health Organisation (WHO) ORS) in reducing stool volume and duration of diarrhoea in children and adults. Rice based ORT has been used only sparingly in young infants, however, because of theoretical concerns about digestibility. A randomised controlled trial of rice based ORT (50 g rice and electrolytes identical to WHO ORS) and WHO ORS was carried out in 52 male infants less than 6 months old with moderately severe acute diarrhoea to evaluate efficacy and digestibility. Nineteen (70%) of 27 children who received rice based ORT and 18 (72%) of 25 children who received WHO ORS were treated successfully. The mean (SD) diarrhoeal stool output for the first 24 hours of treatment was significantly lower in the infants receiving the rice based ORT than in those receiving WHO ORS (101.0 (60.5) v 137.1 (74.6) g/kg). The stool output was also significantly less in the rice based ORT group in the second 24 hours. Infants in the rice based ORT group drank significantly less rehydration solution than infants in the WHO ORS group (mean (SD) 165.4 (77.4) v 217.9 (86.1) during the first 24 hours of treatment. There was no difference in the duration of diarrhoea between the groups. The volume of breast and formula feeding was similar in the two groups. No difference was seen in the frequency of finding reducing substances or acid pH in the stools of either group of children. The results suggest that rice based ORT is as effective as WHO ORS in infants with moderately severe diarrhoea and that rice based ORT is as well tolerated as WHO ORS in infants.

Small intestinal glucoamylase deficiency and starch malabsorption: a newly recognized alpha-glucosidase deficiency in children

To determine the prevalence of short polymers of glucose and starch malabsorption caused by small intestinal glucoamylase deficiency in children with chronic diarrhea, we studied small bowel biopsy specimens from 511 children (aged 1 month to 9 years) with chronic diarrhea evaluated at 54 medical centers. Glucoamylase and disaccharidase (lactase, sucrase, maltase, and palatinase) enzyme assays were performed. Of the 511 children, 15 had glucoamylase deficiency. Six who had significant small intestinal mucosal injury and disaccharidase deficiencies were defined as having secondary glucoamylase deficiency; the other nine patients with normal mucosal morphologic features were defined as having primary glucoamylase deficiency. Secretin tests showed normal pancreatic amylase values for age in all seven children tested. Four of them had abnormal findings on tolerance tests for starch and short polymers of glucose (rise in blood glucose concentration: < 20 mg/dl) and reducing substances in stools, and three of these four had symptoms of intolerance (abdominal distention, flatulence, and diarrhea). All seven patients responded to a starch elimination diet. After reintroduction of a starch diet, diarrhea recurred in four patients; this was alleviated 48 hours after reelimination of starch. We conclude that intestinal glucoamylase deficiency is present in some patients with chronic diarrhea.

Effect of transamniotic administration of epidermal growth factor on fetal rabbit small intestinal nutrient transport and disaccharidase development

As fetal swallowing is documented in utero, supplementation of the ingested amniotic fluid with nutrients or hormones has been postulated as a potential prenatal treatment for intrauterine growth retardation (IUGR). To study the effect of epidermal growth factor (EGF) on the developing fetal small intestine, 12 pregnant rabbits underwent operation on day 24 of a normal 31-day gestation. Bilateral ovarian end fetuses underwent catheterization of their respective amniotic cavities with attachment to a miniosmotic pump. Study fetuses received recombinant human EGF at approximately 300 micrograms/kg/d for 1 week; controls received carrier solution only at an equivalent rate. On gestational day 31, fetuses were delivered by cesarean section and somatic measurements were recorded. The small intestine was harvested and proximal, middle, and distal regions were analyzed for lactase and maltase enzyme activity. Additionally, the uptake of radiolabeled glucose and proline was measured by a standard everted mucosal sleeve technique for each segment. Results were analyzed by Student's paired t test and reported as mean +/- SEM. Nine fetal pairs survived (75%). Small intestinal (SI) length was increased in EGF fetuses (54.8 +/- 1.9 cm) versus control (50.4 +/- 2.7 cm) (P = .02). Lactase activity, reported as UE/g protein, was significantly increased in the proximal segments in the EGF-infused fetuses; maltase was significantly increased in both the proximal and middle segments (P < .05).(ABSTRACT TRUNCATED AT 250 WORDS)

Absorption of glucose polymers from rice in oral rehydration solutions by rat small intestine

BACKGROUND

This study aims to determine the effect of replacing glucose in oral rehydration solution (ORS) with starch hydrolysates from rice on absorption in the small intestine and levels of glucose in portal venous blood and on disaccharidase levels and morphometric measurements in intestines of rats.

METHODS

ORS containing standard composition of salts and 2% glucose (WHO ORS) or 2%, 5%, or 10% starch hydrolysates were infused into duodena of 60 Sprague-Dawley rats (250-350 g). Portal venous blood glucose levels were determined at 0, 30, 60, 90, and 120 minutes.

RESULTS

Significantly larger areas under the curve of glucose absorption (AUCs) were produced by ORS containing 10% unfractionated starch hydrolysates (123.2 +/- 3.8), 2%, 5%, and 10% starch hydrolysates with long-chain ( > 9 molecules) glucose polymers (109.5 +/- 10.6, 109.3 +/- 7.4, and 115.3 +/- 7.1, respectively), and 5% and 10% starch hydrolysates with short-chain (2-9 molecules) glucose polymers (124.4 +/- 6.1 and 128.1 +/- 6.8). ORS with 2% and 5% unfractionated starch hydrolysates and 2% short-chain glucose polymers produced AUCs comparable with those of WHO ORS (96.48 +/- 5.7). Disaccharidase levels and morphometric measurements were not significantly different.

CONCLUSIONS

Starch hydrolysates from rice containing glucose polymers can be used in ORS in higher concentrations than glucose to provide higher caloric density without increased osmolality.

An optimal rice-based oral rehydration solution: the effect of different concentrations of amylase on production of short chain polymers of glucose

As part of a plan to develop a rice-based oral rehydration solution containing short polymers of glucose instead of glucose, we determined the concentration of amylase that would yield the largest amount of short chain polymers. Thai rice (25 g) was boiled with 500 ml of distilled water for 30 min. Of 200 ml supernatant rice water obtained, 100 ml were digested with different amounts of amylase after cooling to 50 degrees C for 60 min, boiled for 5 min, and centrifuged (10,000 g, 25 degrees C) for 60 min. The resulting supernatant (80 ml) was freeze-dried; 1.75 g of the powder obtained were dissolved in 3.5 ml of water, passed through a Bio-Gel P2 column to separate short chain polymers (2-9 molecules of glucose) and long chain polymers (> 9 molecules of glucose), which were identified by spectrophotometry (lambda = 190 nm) or by high performance liquid chromatography. Ten mg of amylase (equivalent to 12,000 modified Wohlgemath units) per 100 ml of rice water was optimal for the production of short polymers of glucose from rice.

Short-chain glucose polymer and anthracene-9-carboxylic acid inhibit water and electrolyte secretion induced by dibutyryl cyclic AMP in the small intestine

Glucose-stimulated sodium absorption is the rationale for treatment with glucose-based oral rehydration solution in diarrhea. Concurrent treatment with pharmacological inhibitors, which specifically block chloride secretion, may be a useful adjunct to oral fluid therapy. To examine this hypothesis, the authors determined the intestinal water and ion transport rates in rat small intestine during the secretory phase induced by perfusion with N6-2'-0-dibutyryl adenosine 3',5'-cyclic monophosphate (dbcAMP), 1.0 mmol/L. A marker (polyethylene glycol 4000) dilution technique was used to evaluate the antisecretory effects of a defined short-chain glucose polymer, D-glucose, and a chloride channel blocker, anthracene-9-carboxylic acid (A-9-C). The results showed that dbcAMP induced small intestinal water and chloride ion secretion rapidly and reliably. The 2.5% concentration of rice short glucose polymer (G2, 22.7%; G3, 28.2%; G4, 14.0%; G5, 16.6%; G6, 11.6%; G7-9, 6.9%) is a better carbohydrate than the 2.5% concentration of D-glucose in reversing secretion of water, chloride, and sodium ions induced by dbcAMP. The combination of A-9-C and the glucose polymer can reverse dbcAMP-induced intestinal secretion and produces significantly (P less than 0.05) better antisecretory effect on water, sodium, and chloride ions than D-glucose with A-9-C.

Glucose polymers as an alternative to glucose in oral rehydration solutions

Several issues involving glucose-based oral rehydration therapy may limit its acceptability and sustained use. Our studies suggest that defined short-chain glucose polymers (2 to 9 glucose units) are hydrolyzed and absorbed faster than isocaloric solutions of D-glucose in the small intestine of the rat. Glucose polymers, primarily from rice-based solutions, have been shown to be as effective as glucose-based solutions. They offer additional advantages in reducing the amount and duration of diarrhea with lesser volumes of solution, thereby reducing the costs of treatment. Rice-based solutions provide high caloric density and increase the absorption of sodium without an osmotic overload. The result is increased net absorption of glucose, sodium, and water. Glucose polymers from rice or other starches in oral rehydration solutions may be effective, inexpensive, easily used, and safe treatments for acute diarrhea.

Rice-based oral electrolyte solutions for the management of infantile diarrhea

BACKGROUND

In infants the treatment of acute diarrhea with glucose-based solutions results in rehydration but does not reduce the severity of diarrhea. Oral rehydration with solutions based on rice powder may reduce stool output as well as restore fluid volume.

METHODS

We designed a prospective, randomized, double-blind study to evaluate the efficacy of two rice-based rehydration solutions and a conventional glucose-based solution. Solution A contained only rice-syrup solids, solution B contained rice-syrup solids and casein hydrolysate, and solution C, the glucose-based solution, served as control. The study subjects were 86 mildly to moderately dehydrated infant boys, 3 to 18 months old, who were admitted to a children's hospital with acute diarrhea. We measured fluid intake, fecal and urine output, and absorption and retention of fluid, sodium, and potassium at intervals for 48 hours in all 86 infants.

RESULTS

The mean (+/- SE) fecal output was significantly lower in the infants given solution A (group A infants) than in the infants given solution C (group C) (29 +/- 4 vs. 46 +/- 7 ml per kilogram of body weight, P less than 0.05) during the first six hours of therapy. The infants in group A also had greater fluid absorption (221 +/- 16 vs. 167 +/- 9 ml per kilogram, P less than 0.05) over the entire 48 hours of therapy and greater potassium absorption (1.6 +/- 0.2 vs. 0.6 +/- 0.1 mmol per kilogram, P less than 0.05) during the first six hours than the infants in group C. Solution B offered no advantages over solution A.

CONCLUSIONS

Solutions containing rice-syrup solids were effective in the rehydration of infants with acute diarrhea. They decreased stool output and promoted greater absorption and retention of fluid and electrolytes than did a glucose-based solution.

Scientifically-based strategies for nutrition of the high-risk low birth weight infant

Technological advances in the intensive care of low birth weight (LBW) infants have resulted in major increases in their survival. New challenges in meeting their nutritional needs have emerged. Very low birth (VLBW) weight infants have very little body fat or glycogen reserves at birth, making them susceptible to starvation. If fed enterally, they require at least 120 calories/kg per day for growth. Numerous immaturities in the gastrointestinal tract and liver limit protein digestion, absorption, and metabolism. Several amino acids not considered essential to the older child or adult are essential to the VLBW infant. Supplying a high protein load with an inappropriate amino acid composition may lead to metabolic imbalances. The digestion and absorption of fats differs from the older child or adult. Lingual and gastric lipases are important, and the lack of bile acids limits fat absorption. Lipoprotein lipase deficiency causes problems when too much fat or fat of incorrect composition is provided. There are controversies regarding the most appropriate carbohydrate source, but research shows that lactose remains an important carbohydrate source for most of these infants. Calcium, magnesium, and phosphorus requirements pose questions in both enterally and parenterally nourished infants. Studies of iron usage suggest that VLBW infants fed either human milk or formula should receive iron supplements. Vitamin E may be helpful in preventing oxygen toxicity. Vitamin D deficiency contributes to bone demineralization and rickets. Controversy exists regarding the correlation between vitamin A nutrition and development of chronic lung disease. Guidelines have been developed for recommended intakes, but much needs to be learned to provide a sound scientific basis upon which to provide optimal nourishment for the high risk, LBW infant.

Glucose therapy for glycogenosis type 1 in infants: comparison of intermittent uncooked cornstarch and continuous overnight glucose feedings

This study was undertaken to test the glycemic response of five infants with glycogen storage disease type 1, aged 0.7 to 1.5 years, to uncooked cornstarch under various dietary conditions, and to evaluate the long-term effects of a dietary regimen consisting of uncooked cornstarch in milk every 4 hours, in addition to three meals daily, on biochemical values and physical growth. The results were compared with previous experience in treating six infants with continuous overnight glucose infusion via gastrostomy plus multiple daily feedings containing an adequate source of glucose. A test dose of cornstarch (1.6 to 1.8 gm/kg) providing four times the calculated hourly glucose production rate, when given in water 15 to 30 minutes after a continuous overnight intragastric glucose infusion was stopped, did not maintain normoglycemia. When the same dose was given in 2% cow milk 4 hours later, mean blood glucose levels remained greater than 68 mg/dl (3.8 mmol/L) for up to 4 hours. A regimen of uncooked cornstarch in 2% cow milk at 4-hour intervals in addition to three meals daily prevented hypoglycemia, and maintained blood lactate at nearly normal levels and serum uric acid and cholesterol within the normal range; triglyceride levels were increased only modestly. Overnight blood glucose levels were comparable to those achieved with continuous intragastric glucose infusion. With this regimen the five infants have maintained linear growth rates normal for their age and genetic potential; the mean percentage of ideal body weight for length percentile did not change significantly, although two of the five patients were overweight (123% and 124% of ideal body weight respectively) after 3 years of treatment. We conclude that a trial of uncooked cornstarch in feedings of milk every 4 hours should be attempted as soon as a more frequent feeding schedule with dextrose-containing formulas proves ineffective, because the former has the potential to provide the continuous glucose required by infants with glycogen storage disease type 1 in a safer and less invasive fashion than continuous intragastric glucose infusion.

Nutritional therapy for infants with diarrhea

The appropriate choice of treatment for infants with diarrhea has long provoked debate. Growth of infants with diarrhea is adversely affected by associated diseases including anorexia, malabsorption, catabolic response to infection, and iatrogenic starvation. To prevent the negative effects of diarrhea on the nutrition of infants, continued feeding during the active and early convalescent phases has been recommended. Although this concept is not new, until recently it has been little used in the treatment of diarrhea. In this article we examine the current knowledge about, and trends in, feeding infants with diarrhea. We will discuss treatments for the well-nourished infant with acute diarrhea, the infant with prolonged diarrhea, and the malnourished infant. Information regarding the use of local staples will also be provided.

Effect of formula carbohydrate concentration on tolerance and macronutrient absorption in infants with severe, chronic diarrhea

To determine how the carbohydrate (CHO) content of "semielemental" formulas affects tolerance and macronutrient absorption, we enrolled 12 infants with severe diarrhea in two successive metabolic balance studies. The infants received, in random order, one of two isocaloric formulas that differed mainly in their CHO and fat concentrations. No significant differences were found between the two feeding periods for peak breath hydrogen levels and fecal osmolality. The low-CHO formula was tolerated better than the high-CHO formula, as indicated by a significantly lower stool output (mean +/- SD 387 +/- 230 vs 764 +/- 443 gm, respectively; p less than 0.05), and higher fecal pH (5.9 +/- 0.7 vs 4.9 +/- 0.5; p less than 0.05). Macronutrient absorption was greater during the ingestion of the low-CHO formula, as indicated by a significantly higher coefficient of fat absorption (p less than 0.005) and lower total fecal energy (mean +/- SD for high- vs low-CHO formula, 372 +/- 205 vs 207 +/- 102 kcal; p less than 0.05), which resulted from a lower CHO excretion (p less than 0.05). A correlation coefficient between the energy derived from CHO in feces and the total stool output was significant for both the high-CHO formula (r = 0.83; p less than 0.001) and the low-CHO formula (r = 0.7; p = 0.01). The CHO concentration of the special infant formula that we tested had an overriding effect on stool output and on fat and energy absorption.

Hydrolysis and absorption of glucose polymers from rice compared with corn in chronic diarrhea of infancy

Because rice remains the most available carbohydrate in developing countries, where chronic diarrhea is most prevalent, we compared the in vitro hydrolysis and clinical tolerance of rice glucose polymer with those of corn glucose polymer. Rice glucose polymer hydrolysis to D-glucose and short-chain polymers (polymers with two to four glucose units and those with five or more units) was similar to that for corn glucose polymers during incubation with saliva or duodenal aspirates. However, rice glucose polymers yielded more short-chain products than corn glucose polymers during incubation with pooled mucosal homogenates (p less than 0.01). In vivo tolerance testing of 16 infants with chronic diarrhea confirmed that rice glucose polymers were well tolerated and, compared with corn glucose polymers, achieved a higher maximal increase of serum glucose concentration (36.6 +/- 7.3 vs 27.6 +/- 10.3 mg/dl; p less than 0.02), a shorter time to peak serum glucose concentration (34.0 +/- 10.2 vs 52.5 +/- 25.7 minutes; p less than 0.02), and a greater area under the serum glucose response curve at 30 minutes (538 +/- 131 vs 1035 +/- 501 cm; p less than 0.02). We conclude that rice glucose polymers are rapidly hydrolyzed in vitro and in vivo and are more rapidly absorbed than are corn glucose polymers in children with chronic diarrhea.

Proximal small intestinal mucosal injury. Maintenance of glucose and glucose polymer absorption, attenuation of disaccharide absorption

The effect of chronic intragastric infusion of hypertonic mannitol on small intestinal mucosal structure and function was studied in adult rats. Animals were gavage-fed 20% mannitol (1300 mosm) at a dose of 5 ml/100 g body weight daily for seven days. Control animals were gavage-fed tap water on the same schedule. On day 8, the animals were anesthetized, the duodenum cannulated, and a test sugar (glucose, glucose polymer, lactose, sucrose, or maltose) was infused at a dose of 0.5 g/kg body weight in 2.5 ml distilled water over less than 1 min. Portal vein glucose was measured at 30-min intervals from 0 to 120 min. Mannitol treatment resulted in histologic and biochemical alterations (reduced lactase, sucrase, maltase) limited to the proximal small intestine compared to the control group. The absorption of glucose and glucose polymers was similar in mannitol-treated and control animals. In contrast, digestion and absorption of lactose, sucrose, and maltose was significantly diminished in mannitol-treated animals when compared to controls. No changes in permeability to polyethylene glycol 4000 or Na+-coupled glucose transport were observed in mannitol-treated animals compared to controls. These data suggest that when the intestinal mucosa is exposed to hyperosmolar loads that the digestive capacity for disaccharides is suppressed more than its glucose absorptive capacities. Furthermore, glucose oligomers may be more readily digested and absorbed than disaccharides, in this setting, due, in part, to the proximal injury and less pronounced proximal-distal gradient for glucoamylase than other brush-border carbohydrases.(ABSTRACT TRUNCATED AT 250 WORDS)

Glycogen storage disease type I and III and pyruvate carboxylase deficiency: results of long-term treatment with uncooked cornstarch

Three patients with glycogen storage disease type I (GSD-I), three with glycogen storage disease type III (GSD-III) and one with pyruvate carboxylase deficiency (PCD) could be successfully switched over from continuous nocturnal gastric drip feeding (GDF) to nocturnal feeding with uncooked cornstarch in yoghurt or "quark" (CSF) at the age of 4-20 years. The new kind of therapy is much more convenient for the patients. When followed up to 30 months, patients on CSF showed the same clinical and laboratory findings as during the last two years with GDF. CSF was not introduced to three patients with GSD-I. Two of them refused the permanent starch-yoghurt meals. In the third patient the morning blood glucose concentrations were too variable.

Disorders of carbohydrate digestion and absorption

The carbohydrate malabsorptive syndromes are frequently seen by pediatricians. The congenital deficiency states are quite rare, but adult type hypolactasia and lactose intolerance following rotavirus infection are recognized with increasing frequency by primary care physicians. Therapy for these disorders involves identification of the offending carbohydrate, removal of the carbohydrate from the diet, and exclusion of other entities that may result in carbohydrate malabsorption but not respond to its removal from the diet. Prognosis for both the primary and secondary carbohydrate malabsorption syndromes is excellent. Compliance with diets for those pediatric patients who will require lifelong therapy remains problematic.

Feeding the premature and compromised infant: gastrointestinal considerations

We have presented the current concepts of gastrointestinal ontogeny--the various factors governing the ontogeny of the gastrointestinal tract and the interaction and intricate relationship between different determinants. It is only through a better understanding of the development of the gut and the various factors affecting it that pediatric gastroenterologists are able to design nutritional support strategies for managing very young and compromised neonates.

Enzyme-substitution therapy with the yeast Saccharomyces cerevisiae in congenital sucrase-isomaltase deficiency

Sucrase-isomaltase deficiency is an inherited disaccharidase deficiency that leads to malabsorption of sucrose, with resulting diarrhea and abdominal distention and cramps. We investigated the sucrose-splitting effect of viable yeast cells in eight children with congenital sucrase-isomaltase deficiency, by means of the sucrose hydrogen breath test. This test is based on the fact that hydrogen is released from the malabsorbed sucrose by the colonic microflora. We found that 0.3 g of lyophilized Saccharomyces cerevisiae, given after loading with 2 g of sucrose per kilogram of body weight, reduced hydrogen excretion in all patients, on average by 70 percent, in parallel with a complete loss or evident reduction of clinical symptoms. In vitro, lyophilized and fresh S. cerevisiae (fresh baker's yeast) had appreciable sucrase activity, a low isomaltase and maltase activity, and virtually no lactase activity. The sucrase activity was more inhibited by undiluted than by diluted gastric juice. We conclude that patients with congenital sucrase-isomaltase deficiency who intentionally or unintentionally consume sucrose can ameliorate the malabsorption by subsequently ingesting a small amount of viable yeast cells, preferably on a full stomach.

The enzymology of intestinal disease

The role of enzyme estimations is reviewed. Serum levels of most enzymes do not alter significantly in intestinal diseases because dying mucosal cells slough off into the lumen. Similarly, biopsy material may provide misleading results because of lack of homogeneity between diseased and normal segments of bowel, whether in inflammatory or neoplastic conditions. Lactase deficiency is the most common intestinal enzyme deficiency. The once popular lactose tolerance test is lately giving way to the breath hydrogen test, which generally reflects unabsorbed carbohydrate reaching the colon. This test and its clinical usefulness are reviewed in some detail, and the use of lactulose as an indicator of intestinal transit is also discussed.

The impact of development of the gut on infant nutrition

We have described the developmental pattern of the GI tract, constituent tissues of which do not develop simultaneously, either functionally or morphologically. Dietary modifications to suit the stage of development have been described, and possible changes resulting from these modifications are also discussed. It is important to note that the newborn period is a time in which rapid development is taking place while the GI system is still not fully mature, hence the macro- and micronutrients given during this period should be adjusted both quantitatively and qualitatively to suit the needs of the infant, particularly so if he is premature or compromised.

[Physiologic nutritional evaluation of complete infant nutrition based on a soybean formula]

The purpose of this review is to evaluate the nutritional quality of soybean-based infant diets on the basis of results published in the scientific literature. Special consideration has been given to the use of soybean protein formulas for infants with reduced intestinal digestion and absorption capacity as well as in cases of cow's milk intolerance and allergic diseases.

Corn syrup sugars: in vitro and in vivo digestibility and clinical tolerance in acute diarrhea of infancy

We evaluated the in vitro and in vivo digestibility and clinical tolerance of three corn syrup sugars (DE10, 15, 24) and one infant formula containing corn syrup sugar as the sole carbohydrate source (DE24). In vitro studies were conducted using human duodenal fluid and jejunal mucosa with normal enzyme activities. In vivo studies included intragastric perfusion studies and tolerance tests using the corn syrup sugars and a clinical formula trial in 32 infants with acute diarrhea. Results of the in vitro studies showed that each of the corn syrup sugars was well hydrolyzed by duodenal fluid and by mixtures of duodenal fluids and mucosal homogenates. Similarly, in vivo studies revealed significant hydrolysis in the proximal intestine, as measured during the perfusion studies, and adequate absorption, as indicated by a rise in serum glucose concentration during tolerance tests. Only patients who had a marginal serum glucose rise after a glucose meal had a blunted rise after a corn syrup feeding. More than 85% of the infants beginning the clinical trial tolerated the formula well and gained weight at or above the expected rate for age during the study interval. These data indicate that, except with severe mucosal injury and secondary monosaccharide intolerance, glucose polymers of the dextrose equivalents tested are suitable carbohydrate sources for infants recovering from acute diarrhea.

Carbohydrate malabsorption in infants with diarrhea studied with the breath hydrogen test

Fermentation of malabsorbed carbohydrate (CHO) reaching the colon was studied by measuring peak breath hydrogen (H2) production between feedings in 28 H2-producing hospitalized infants with diarrhea. Patients who required fewer than six days of hospitalization had lower breath H2 values when tested soon after admission than those who required longer stays. Patients hospitalized for more than five days had lower H2 amounts at discharge than on admission. Peak breath H2 values decreased when glucose was substituted for glucose polymers in formulas, or when the formula was fed by continuous drip via a nasogastric tube instead of by orally administered bolus. Glucose-positive and acidic stools were encountered occasionally and were associated with decreased H2 levels. The responses of H2 levels, stool pH, and glucose excretion after changes in patient management or intestinal metabolism of CHO reflect alterations in the balance between proximal intestinal absorption and distal colonic fermentation. Malabsorbed CHO that reaches a competent colon is utilized via microbial conversion, as indicated by high H2 levels, in the absence of glucose-positive and acidic stools. The presence of glucose in the feces or acidic stools indicates an inability of the colon to completely metabolize and absorb CHO or its products of fermentation.

Impact of development of the gastrointestinal tract on infant feeding

We have described the developmental pattern of the gastrointestinal tract under optimal conditions (i.e., low risk pregnancy and normal labor and delivery at term). The tissues do not develop simultaneously, and morphologic and functional development are not concurrent. An important consideration is the effect of suboptimal or even adverse conditions on the developmental sequence and attainment of maturity. Malnutrition during both the prenatal and postnatal periods may restrict the morphologic and biochemical development of the gastrointestinal tract. Dietary modifications have been shown to alter the developmental pattern of intestinal and pancreatic enzymes in animal models. Drugs and hormonal therapy given during pregnancy and early infancy have been known to cause developmental defects, but the specific effects on the gastrointestinal tract have not been evaluated. For further understanding of digestibility of nutrients and absorption in the perinatal period, these departures from the normal development of the gastrointestinal tract and the mechanisms by which these potential effects occur remain to be described. In view of these undetermined factors, in the case of intolerance or unavailability of milk from the natural mother, feedings should be individualized, with attention to direct measurement of enzyme concentrations, balance studies, or both, especially in the case of extreme prematurity or unusual requirements.