Stool and urine trefoil factor 3 levels: associations with symptoms, intestinal permeability, and microbial diversity in irritable bowel syndrome

Previously we showed that urine trefoil factor 3 (TFF3) levels were higher in females with irritable bowel syndrome (IBS) compared to non-IBS females. To assess if TFF3 is associated with symptoms and/or reflect alterations in gastrointestinal permeability and gut microbiota in an IBS population, we correlated stool and urine TFF3 levels with IBS symptoms, intestinal permeability, stool microbial diversity and relative abundance of predominant bacterial families and genera. We also tested the relationship of stool TFF3 to urine TFF3, and compared results based on hormone contraception use. Samples were obtained from 93 females meeting Rome III IBS criteria and completing 4-week symptom diaries. TFF3 levels were measured by ELISA. Permeability was assessed with the urine lactulose/mannitol (L/M) ratio. Stool microbiota was assessed using 16S rRNA. Stool TFF3, but not urine TFF3, was associated positively with diarrhoea and loose stool consistency. Higher stool TFF3 was also associated with lower L/M ratio and microbial diversity. Of the 20 most abundant bacterial families Mogibacteriaceae and Christensenellaceae were inversely related to stool TFF3, with only Christensenellaceae remaining significant after multiple comparison adjustment. There were no significant relationships between stool or urine TFF3 levels and other symptoms, nor between stool and urine levels. In premenopausal females, urine TFF3 levels were higher in those reporting hormone contraception. Collectively these results suggest that higher stool TFF3 levels are associated with IBS symptoms (loose/diarrhoeal stools), lower gut permeability, and altered stool bacteria composition (decreased diversity and decreased Christensenellaceae), which further suggests that TFF3 may be an important marker of host-bacteria interaction.

Randomised clinical trial: gut microbiome biomarkers are associated with clinical response to a low FODMAP diet in children with the irritable bowel syndrome

BACKGROUND

A low fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAP) diet can ameliorate symptoms in adult irritable bowel syndrome (IBS) within 48 h.

AIM

To determine the efficacy of a low FODMAP diet in childhood IBS and whether gut microbial composition and/or metabolic capacity are associated with its efficacy.

METHODS

In a double-blind, crossover trial, children with Rome III IBS completed a 1-week baseline period. They then were randomised to a low FODMAP diet or typical American childhood diet (TACD), followed by a 5-day washout period before crossing over to the other diet. GI symptoms were assessed with abdominal pain frequency being the primary outcome. Baseline gut microbial composition (16S rRNA sequencing) and metabolic capacity (PICRUSt) were determined. Metagenomic biomarker discovery (LEfSe) compared Responders (≥50% decrease in abdominal pain frequency on low FODMAP diet only) vs. Nonresponders (no improvement during either intervention).

RESULTS

Thirty-three children completed the study. Less abdominal pain occurred during the low FODMAP diet vs. TACD [1.1 ± 0.2 (SEM) episodes/day vs. 1.7 ± 0.4, P < 0.05]. Compared to baseline (1.4 ± 0.2), children had fewer daily abdominal pain episodes during the low FODMAP diet (P < 0.01) but more episodes during the TACD (P < 0.01). Responders were enriched at baseline in taxa with known greater saccharolytic metabolic capacity (e.g. Bacteroides, Ruminococcaceae, Faecalibacterium prausnitzii) and three Kyoto Encyclopedia of Genes and Genomes orthologues, of which two relate to carbohydrate metabolism.

CONCLUSIONS

In childhood IBS, a low FODMAP diet decreases abdominal pain frequency. Gut microbiome biomarkers may be associated with low FODMAP diet efficacy. ClinicalTrials.gov identifier: NCT01339117.

Neuroimmune interactions at different intestinal sites are related to abdominal pain symptoms in children with IBS

BACKGROUND

Neuroimmune interactions and inflammation have been proposed as factors involved in sensory-motor dysfunction and symptom generation in adult irritable bowel syndrome (IBS) patients. In children with IBS and healthy controls, we measured ileocolonic mast cell infiltration and fecal calprotectin and evaluated the relationships between these parameters and abdominal pain symptoms and stooling pattern.

METHODS

Irritable bowel syndrome patients diagnosed according to Pediatric Rome III criteria and healthy controls kept a 2-week pain/stooling diary. Ileocolonic mucosal mast cells (MC) and MC in close proximity to nerve fibers (MC-NF) were identified immunohistochemically and quantified. Fecal calprotectin concentration was measured.

KEY RESULTS

21 IBS patients and 10 controls were enrolled. The MC-NF count was significantly higher in the ileum (p = 0.01), right colon (p = 0.04), and left colon (p < 0.001) of IBS patients compared with controls. No differences in fecal calprotectin concentration were noted. Abdominal pain intensity score correlated with ileal MC count (r(s) = 0.47, p = 0.030) and right colon MC-NF count (r(s) = 0.52, p = 0.015). In addition, children with IBS with >3 abdominal pain episodes/week had greater ileal (p = 0.002) and right colonic (p = 0.01) MC counts and greater ileal (p = 0.05) and right colonic (p = 0.016) MC-NF counts than children with less frequent pain. No relationship was found between MC and MC-NF and fecal calprotectin or stooling pattern.

CONCLUSIONS & INFERENCES

Mast cells-nerve fibers counts are increased in the ileocolonic mucosa of children with IBS. Mast cells and MC-NF counts are related to the intensity and frequency of abdominal pain.

The interpretation of Rome III criteria and method of assessment affect the irritable bowel syndrome classification of children

BACKGROUND

Paediatric classification of irritable bowel syndrome (IBS) is complicated by the potential discrepancy between parent and child report and by the interpretation of pain-stool relations in the Rome III classification system.

AIM

To compare IBS classification by diary and by child and parent respondents.

METHODS

Children (ages 7-10 years, n = 90) with recurrent abdominal pain and their parents completed IBS symptom questionnaires and 2-week pain and stool diaries. Diaries were coded with two algorithms, one defining stool changes individually and one defining changes normatively. Proportions of dichotomous classifications (IBS vs. not IBS) between pairs of classification methods/respondents were evaluated using Chi-squared tests (χ²) to determine whether coding methods were significantly related, the degree of inclusiveness, and whether differences in classification were randomly distributed.

RESULTS

Individual and normative diary classifications were congruent in 62% of cases, but the individual method classified more children with IBS, 53% vs. 18%. Parent and child questionnaire reports were not correlated. The normative diary classifications and parent questionnaire were the most congruent pair of methods (76% of cases).

CONCLUSIONS

Poor congruence among methods suggests that Rome III IBS criteria need better specification, and efforts to improve parent-child agreement are necessary.

Diagnostic yield of oesophagogastroduodenoscopy in children with abdominal pain

BACKGROUND

Abdominal pain is the most common indication for oesophagogastroduodenoscopy (OGD) in children. However, existing studies examining the diagnostic outcomes of OGD in children with abdominal pain are limited.

AIM

To examine the diagnostic yield of OGD with biopsy in the evaluation of abdominal pain and to describe the endoscopic and histological findings in patients undergoing OGD for abdominal pain of unclear aetiology.

METHODS

We performed a retrospective cross-sectional cohort study in children under 18 years of age who had OGD for the primary indication of abdominal pain, at Texas Children's Hospital and Children's Hospital of The King's Daughters from 1 January 2002 to 30 June 2005.

RESULTS

Overall, OGD was diagnostic in 454 (38.1%) of the 1191 procedures, including reflux oesophagitis (23%, n = 271), Helicobacter pylori infections (5%, n = 55), peptic ulcers (3%, n = 32), eosinophilic oesophagitis (2%, n = 25), celiac disease (1%, n = 9) and Crohn's disease (0.5%, n = 7). Male gender, older age, elevated C-reactive protein and vomiting were associated with increased diagnostic yield.

CONCLUSIONS

Our findings suggest that OGD is valuable for the evaluation of chronic abdominal pain in children, with a diagnostic yield of 38%. The majority of alarm symptoms and routine laboratory tests are not significantly associated with diagnostic yield.

Feeding colostrum rapidly alters enzymatic activity and the relative isoform abundance of jejunal lactase in neonatal pigs

Our objective was to determine the short-term effects of feeding colostrum and mature milk on the enzyme activity and relative isoform abundance of lactase in neonatal pigs. We studied newborn pigs that were fed colostrum, mature milk and water for 6 h (Study 1). We also studied unfed pigs shortly after birth, and newborn pigs fed either colostrum or mature milk for 24 h (Study 2). The specific activity (micromol x min(-1) x g protein(-1)) of lactase in ajejunal mucosal homogenate and a purified membrane fraction was lower in pigs fed colostrum than in unfed newborns or those fed either milk or water. However, after 24 h, total jejunal lactase activity (micromol x mol(-1)), jejunal mass and protein content were higher in the colostrum- and milk-fed pigs than in the unfed newborns. In colostrum-fed pigs, the reduction in lactase specific activity after 6 h was associated with 1) a marked increase in the relative abundance of a 180-kDa protein, which was shown to be one of three pro-lactase isoforms, and 2) a lower relative abundance of the 160-kDa isoform, considered to be the mature form of the enzyme. Our evidence suggests that feeding either colostrum or mature milk increases total jejunal lactase activity. The reduction in both the specific activity and abundance of the mature isoform in conjunction with an increased relative abundance of the 180-kDa pro-lactase isoform suggests that feeding colostrum alters the post-translational processing of intestinal lactase in neonatal pigs.

Effect of enteral administration of insulin on intestinal development and feeding tolerance in preterm infants: a pilot study

OBJECTIVE

To determine in a pilot study whether enteral administration of insulin to preterm infants (26-29 weeks of gestational age) would enhance gastrointestinal development and reduce feed intolerance without adverse effects.

DESIGN

Eight preterm infants were given 4 U/kg/day insulin enterally from 4 to 28 days of age. Lactase activity was measured at 28 days of age, while measures of feed intolerance were made throughout the hospital stay. The results were compared with those of a matched historical cohort of 80 preterm infants.

SETTING

Tertiary care, university affiliated hospital.

MAIN OUTCOME MEASURES

Lactase activity and feed intolerance.

RESULTS

No adverse effects, such as hypoglycaemia, were observed after administration of insulin. The infants who received insulin had higher lactase activity and less feed intolerance than the controls (30% shorter time to full enteral feeds; fewer gastric residuals per infant).

CONCLUSION

These preliminary data suggest that enteral insulin administration may be of benefit in reducing feed intolerance in preterm infants. A randomised, blinded trial is warranted.

Effects of age, feeding regimen, and glucocorticoids on catecholamine and cortisol excretion in preterm infants

BACKGROUND

The sympathoadrenal system is important in maintaining normal physiologic functioning in infants and increased output also can reflect stress. We sought to determine the effects of age, feeding regimen, and glucocorticoids on catecholamine and cortisol excretion in preterm infants and to assess whether a particular strategy of feeding enhanced sympathoadrenal development or was stressful.

METHODS

Preterm infants (26-30 wk gestation; n = 171) were assigned randomly to begin trophic feedings from day 4 through 14 (trophic group) or to start feedings at day 15 (standard group) with feedings administered either by bolus every 3 hours (bolus) or continuously over 24 hours (continuous). At 10, 28, 40, 50, and 60 days of age, urine was collected continuously for 6 hours for measurement of catecholamines (norepinephrine, epinephrine, dopamine), cortisol, and creatinine. Data were available for 98 infants.

RESULTS

Norepinephrine excretion increased with postnatal age. The increase with age was significantly greater in the trophic group compared with that in the standard group. Epinephrine excretion did not change with age, and there were no differences between trophic and standard groups. Dopamine excretion increased with age but was similar between trophic and standard groups (borderline significantly greater in the trophic group). Cortisol excretion increased with age and also was similar between trophic and standard groups. There was no effect on catecholamine or cortisol excretion of bolus vs continuous feedings, antenatal or postnatal corticosteroids, gestational age at birth, age at which full feedings were attained, or use of human milk compared with preterm formula.

CONCLUSIONS

The greatest determinant of catecholamine and cortisol excretion is postnatal age. Feeding method, type of feeding, and glucocorticoid administration in the amounts customarily used have little significant effect on catecholamine or cortisol excretion. The apparent link between early feeding and norepinephrine (and possibly dopamine) excretion warrants further investigation.

Characterization of the developmental stages of sucking in preterm infants during bottle feeding

It is acknowledged that the difficulty many preterm infants have in feeding orally results from their immature sucking skills. However, little is known regarding the development of sucking in these infants. The aim of this study was to demonstrate that the bottle-feeding performance of preterm infants is positively correlated with the developmental stage of their sucking. Infants' oral-motor skills were followed longitudinally using a special nipple/bottle system which monitored the suction and expression/compression component of sucking. The maturational process was rated into five primary stages based on the presence/absence of suction and the rhythmicity of the two components of sucking, suction and expression/compression. This five-point scale was used to characterize the developmental stage of sucking of each infant. Outcomes of feeding performance consisted of overall transfer (percent total volume transferred/volume to be taken) and rate of transfer (ml/min). Assessments were conducted when infants were taking 1-2, 3-5 and 6-8 oral feedings per day. Significant positive correlations were observed between the five stages of sucking and postmenstrual age, the defined feeding outcomes, and the number of daily oral feedings. Overall transfer and rate of transfer were enhanced when infants reached the more mature stages of sucking. We have demonstrated that oral feeding performance improves as infants' sucking skills mature. In addition, we propose that the present five-point sucking scale may be used to assess the developmental stages of sucking of preterm infants. Such knowledge would facilitate the management of oral feeding in these infants.

New developments in total parenteral nutrition for children

The field of parenteral nutrition continues to evolve along two major paths: prevention of complications and refining of nutritional needs. Parenteral nutrition-associated liver disease remains a vexing problem. No single factor is to blame; rather, it requires a number of "hits." In the infant, the liver disease primarily appears to be related to prematurity of bile flow and production, infection, lack of enteral feedings, and most recently appreciated, perhaps free radicals. We are able to meet the nutritional needs of our patients, but our knowledge of actual nutritional requirements remains incomplete. Future studies need to define better appropriate intakes and to rigorously test the utility of proposed nutrients such as glutamine.

Feeding tolerance in premature infants fed fortified human milk

BACKGROUND

To evaluate feeding tolerance in premature infants immediately after the addition of human milk fortifier (HMF) to their expressed human milk diet.

METHODS

Data on milk intake, feeding tolerance, and related assessments and growth milestones from a prospective study of feeding strategies in premature infants were analyzed. The database was searched for the first day HMF was added to the feeding of infants receiving human milk exclusively. The following assessments were tabulated for the 5 days before and the 5 days after the addition of HMF: milk intake, the number of episodes of abdominal distension, gastric residual volume (GRV) more than 2 ml/kg and more than 50% of the volume fed in the prior 3 hours. bile-stained gastric residual, emesis or regurgitation, blood in the stool, the number of abdominal radiographs, the number of episodes of apnea and bradycardia, changes in findings in the clinical examination, and the number of hours feeding was withheld. The time to achieve full tube feeding, complete oral feeding, and hospital discharge were recorded.

RESULTS

Seventy-six exclusively human milk-fed premature infants (birth weight, 1065+/-18 g; gestational age, 27+/-0.1 weeks; mean +/- SEM) who received HMF beginning 22+/-0.8 days of age were evaluated. There were significant increases in milk intake and in the number of episodes of GRV more than 2 ml/kg and emesis after the addition of HMF. There were no differences in the number of hours feeding was withheld or any other assessment after the addition of HMF. Infants with increases in GRV more than 2 ml/kg and/or emesis after the addition of HMF were not more likely to be delayed in the time to achieve full tube feeding, complete oral feeding, or hospital discharge than infants who did not experience these events.

CONCLUSION

These data suggest that, when all feeding and related assessments and the time to achieve important growth milestones are considered, the addition of HMF does not adversely affect the outcome of the premature infant.

In vivo measurements of glucose absorption in preterm infants

Few data are available regarding the kinetics of glucose absorption in the preterm infant. In order to ascertain the kinetics of glucose absorption in the premature infant and how rate of infusion and concentration affect absorption, jejunal glucose absorption kinetics were measured in 16 preterm infants by infusing 1, 10, and 100 mM glucose solutions in random order. Seventeen infants were perfused with glucose (100 micromol/min) by infusing 67 mM glucose at 1.5 ml/min and 133 mM glucose at 0.75 ml/min to determine the effect of changes in rate of infusion vs. concentration on glucose absorption. Km and Vmax were related to postnatal age. Km was correlated inversely with the percentage of feedings received as human milk. Antenatal administration of glucocorticoids appeared to increase Vmax. The higher infusion rate resulted in greater glucose absorption than the higher concentration glucose solution.

CONCLUSIONS

The characteristics of glucose absorption in the preterm infant change with age and are affected by diet, glucocorticoids, and the method of infusion. These data have implications for the feeding of preterm infants.

Feeding strategies for premature infants: beneficial outcomes of feeding fortified human milk versus preterm formula

BACKGROUND

In a large-scale study of feeding strategies in premature infants (early vs later initiation of enteral feeding, continuous vs bolus tube-feeding, and human milk vs formula), the feeding of human milk had more effect on the outcomes measured than any other strategy studied. Therefore, this report describes the growth, nutritional status, feeding tolerance, and health of participating premature infants who were fed fortified human milk (FHM) in comparison with those who were fed exclusively preterm formula (PF).

METHODS

Premature infants were assigned randomly in a balanced two-way design to early (gastrointestinal priming for 10 days) versus late initiation of feeding (total parenteral nutrition only) and continuous infusion versus intermittent bolus tube-feeding groups. The type of milk was determined by parental choice and infants to receive their mother's milk were randomized separately from those to receive formula. The duration of the study spanned the entire hospitalization of the infant. To evaluate human milk versus formula feeding, we compared outcomes of infants fed >50 mL. kg-1. day-1 of any human milk (averaged throughout the hospitalization) with those of infants fed exclusively PF. Growth, feeding tolerance, and health status were measured daily. Serum indices of nutritional status were measured serially, and 72-hour nutrient balance studies were conducted at 6 and 9 weeks postnatally.

RESULTS

A total of 108 infants were fed either >50 mL. kg-1. day-1 human milk (FHM, n = 62) or exclusively PF (n = 46). Gestational age (28 +/- 1 weeks each), birth weight (1.07 +/- 0.17 vs 1.04 +/- 0.19 kg), birth length and head circumference, and distribution among feeding strategies were similar between groups. Infants fed FHM were discharged earlier (73 +/- 19 vs 88 +/- 47 days) despite significantly slower rates of weight gain (22 +/- 7 vs 26 +/- 6 g. kg-1. day-1), length increment (0.8 +/- 0.3 vs 1.0 +/- 0.3 cm. week-1), and increment in the sum of five skinfold measurements (0.86 +/- 0.40 vs 1.23 +/- 0.42 mm. week-1) than infants fed PF. The incidence of necrotizing enterocolitis and late-onset sepsis was less in the FHM group. Overall, there were no differences in any measure of feeding tolerance between groups. Milk intakes of infants fed FHM were significantly greater than those fed PF (180 +/- 13 vs 157 +/- 10 mL. kg-1. day-1). The intakes of nitrogen and copper were higher and magnesium and zinc were lower in group FHM versus PF. Fat and energy absorption were lower and phosphorus, zinc, and copper absorption were higher in group FHM versus PF. The postnatal retention (balance) surpassed the intrauterine accretion rate of nitrogen, phosphorus, magnesium, zinc, and copper in the FHM group, and of nitrogen, magnesium, and copper in the PF group.

CONCLUSIONS

Although the study does not allow a comparison of FHM with unfortified human milk, the data suggest that the unique properties of human milk promote an improved host defense and gastrointestinal function compared with the feeding of formula. The benefits of improved health (less sepsis and necrotizing enterocolitis) associated with the feeding of FHM outweighed the slower rate of growth observed, suggesting that the feeding of FHM should be promoted actively in premature infants.

Feeding strategies for premature infants: randomized trial of gastrointestinal priming and tube-feeding method

BACKGROUND

Data on enteral feeding management of premature infants are limited and often not the subject of randomized clinical trials. Several small studies suggest benefits from the early initiation of feeding, but do not assess the combined effects of time of initiation of feeding, tube-feeding method, and type of milk used. Either singly or in combination, these treatments may affect growth, bone mineralization, biochemical measures of nutritional status, and feeding tolerance, and, ultimately, the duration of hospitalization.

METHODS

A total of 171 premature infants, stratified by gestational age (26 to 30 weeks) and diet (human milk or preterm formula) were assigned randomly among four treatment combinations in a balanced two-way design comparing the presence or absence of gastrointestinal (GI) priming for 10 days and continuous infusion versus intermittent bolus tube-feeding.

RESULTS

The major outcome, time required for infants to attain full oral feeding, was similar among treatments. GI priming was not associated with any measured adverse effect and was associated with better calcium and phosphorus retention, higher serum calcium and alkaline phosphatase activity, and shorter intestinal transit times. The bolus tube-feeding method was associated with significantly less feeding intolerance and greater rate of weight gain than the continuous method. In addition, the greater the quantity of human milk fed, the lower the morbidity.

CONCLUSIONS

Early GI priming with human milk, using the bolus tube-feeding method, may provide the best advantage for the premature infant.

Early feeding, feeding tolerance, and lactase activity in preterm infants

OBJECTIVE

We sought to ascertain whether the timing of feeding initiation affected the development of intestinal lactase activity and whether there are clinical ramifications of lower lactase activity.

STUDY DESIGN

Preterm infants (26 to 30 weeks' gestation; n = 135) were randomly assigned to begin enteral feedings at either 4 (early group) or 15 days of age (standard group). At 10, 28, and 50 days of age lactase activity was determined by measuring the urinary ratio of lactulose/lactose after the 2 sugars were administered.

RESULTS

Lactase activity increased significantly over time. Infants in the early group had greater lactase activity at 10 days of age (by 100%) and 28 days of age (by 60%) than the standard group. At 10 days of age lactase activity was greater in milk- versus formula-fed infants. The time required to achieve full enteral feedings, the number of abnormal abdominal x-ray examinations, and the total number of abdominal x-ray examinations were inversely related to lactase activity.

CONCLUSIONS

Early feeding increases intestinal lactase activity in preterm infants. Lactase activity is a marker of intestinal maturity and may influence clinical outcomes. Whether the effects of milk on lactase activity were due to the greater concentration of lactose in human milk compared with that in formula must be determined.

Early feeding, antenatal glucocorticoids, and human milk decrease intestinal permeability in preterm infants

To determine the effects of age, feeding regimen, and antenatal glucocorticoids on intestinal permeability, preterm infants (n = 132) were stratified by gestational age and by diet (mothers' own milk versus preterm formula), and assigned randomly to one of four feeding regimens: early-continuous, early-bolus, standard-continuous, and standard-bolus. At 10, 28, and 50 d of age permeability was determined by measuring the ratio of lactulose/ mannitol in the urine after the two sugars were administered enterally for 30 h. The mean (+/-SE) birth weight and gestational age of the infants were 1044 +/- 13 g and 27 +/- 0.1 wk, respectively. Permeability changed as a function of age (p = 0.003). Early feeding was associated with a reduction in permeability at 10 d of age (p = 0.01). Antenatal steroid administration was associated with decreased permeability at 28 d of age (p = 0.017). The feeding of human milk (versus formula) was associated with decreased permeability at 28 d of age (p = 0.02). Continuous versus bolus feeding did not affect permeability.

Central venous catheters versus peripheral veins for sampling blood levels of commonly used drugs

BACKGROUND

Our objective was to compare the accuracy of drug levels in blood samples obtained from central venous catheters with those from peripheral blood samples taken to monitor various drug levels.

METHODS

Pediatric patients with central venous catheters receiving aminoglycosides, vancomycin, or cyclosporine had central and peripheral blood samples obtained within 5 minutes of each other and analyzed simultaneously. We ascertained how well blood levels from central venous catheters compared with those from peripheral blood (the criterion standard).

RESULTS

There were no clinically significant differences between central and peripheral values for amikacin, gentamicin, tobramycin, and vancomycin (both peaks and troughs). Preliminary data indicated that oral cyclosporine can be monitored via central venous catheter. In contrast, there was poor agreement between peripheral and central values when cyclosporine was administered by IV.

CONCLUSIONS

Amikacin, gentamicin, tobramycin, vancomycin, and probably oral cyclosporine can be monitored accurately via central venous catheter. In contrast, IV cyclosporine should be monitored via peripheral blood.

Oral feeding in low birth weight infants

To gain a better understanding of the development of sucking behavior in low birth weight infants, the aims of this study were as follows: (1) to assess these infants' oral feeding performance when milk delivery was unrestricted, as routinely administered in nurseries, versus restricted when milk flow occurred only when the infant was sucking; (2) to determine whether the term sucking pattern of suction/ expression was necessary for feeding success; and (3) to identify clinical indicators of successful oral feeding. Infants (26 to 29 weeks of gestation) were evaluated at their first oral feeding and on achieving independent oral feeding. Bottle nipples were adapted to monitor suction and expression. To assess performance during a feeding, proficiency (percent volume transferred during the first 5 minutes of a feeding/total volume ordered), efficiency (volume transferred per unit time), and overall transfer (percent volume transferred) were calculated. Restricted milk flow enhanced all three parameters. Successful oral feeding did not require the term sucking pattern. Infants who demonstrated both a proficiency > or = 30% and efficiency > or = 1.5 ml/min at their first oral feeding were successful with that feeding and attained independent oral feeding at a significantly earlier postmenstrual age than their counterparts with lower proficiency, efficiency, or both. Thus a restricted milk flow facilitates oral feeding in infants younger than 30 weeks of gestation, the term sucking pattern is not necessary for successful oral feeding, and proficiency and efficiency together may be used as reliable indicators of early attainment of independent oral feeding in low birth weight infants.

Determinants of lactose digestion in the miniature pig

Although lactose is an important nutrient in the diet of the infant and child, the factors contributing to its digestion have not been clarified adequately. We sought to determine the degree to which lactase activity and small intestinal transit explain lactose digestion, the average error (SEE) in estimating lactose digestion using these parameters, and the effect of age. We compared lactose digestion from both a 7% lactose-containing formula and a solution by determining lactose in ileostomy output in pig littermates at 10 days, 4 weeks, and 10 weeks of age. The entire small intestinal mucosa was assayed for lactase specific activity (micromol x min-1 x g protein-1), total activity (micromol x min-1), and whole-villus lactase activity. Transit time (min), and transit rate (cm/min) were measured. Meal type did not affect lactose digestion. Lactose digestion was explained best by lactase specific activity (formula, R2 = 0.73, SEE = 1.1; solution, R2 = 0.69, SEE = 1.0; P < 0.001). The next best parameter was total transit rate (formula, R2 = 0.69, SEE = 2.0; solution, R2 = 0.46, SEE = 1.3). The relationship with lactase specific activity was age related and there appeared to be a critical value of lactase specific activity above which essentially all the lactose was digested.

Effect of carbohydrates on calcium absorption in premature infants

Premature infants are susceptible to disease related to deficient dietary calcium intake. Studies in adults suggest carbohydrates can enhance calcium absorption. However, little is known about how carbohydrates affect calcium absorption in premature infants due to a lack of direct in vivo studies. We adapted the triple lumen perfusion method for use in premature infants to compare calcium absorption 36 mmol/L (1.44 g/L) in the absence and presence of either 70 g/L lactose or glucose polymers. 44Ca was added to determine endogenous calcium losses. Fourteen infants were studied (gestational age: 31 +/- 0.4 wk; study weight: 1590 +/- 105 g; mean +/- SEM). Calcium absorption from the glucose polymer solution was greater than that from the control and lactose solutions (0.17 +/- 0.05 mumol.min-1.cm-1 versus 0.04 +/- 0.04 and 0.008 +/- 0.045 mumol.min-1.cm-1, respectively). Calcium absorption correlated positively with water and carbohydrate absorption. The rate of carbohydrate absorption was greater from the glucose polymers than from the lactose solution (0.40 +/- 0.10 mg.min-1.cm-1 versus 0.22 +/- 0.06, respectively). Based upon 44Ca absorption, endogenous calcium loss appeared to account for less than 1% of total calcium flux. We conclude that glucose polymers, but not lactose, enhance calcium absorption in the premature infant, a fact that may be useful in formula design.

Cereal feeding and its impact on the nitrogen economy of the infant

To quantify the effect of rice cereal on nitrogen balance and fecal nitrogen excretion, and the contribution of endogenous nitrogen sources to fecal nitrogen output, nine infants aged 3-5 mo received [15N]glycine in all feedings. Samples of urine and feces were obtained daily and analyzed for nitrogen and 15N. On days 1-7 the infants received only formula, and a complete urine and fecal collection was made on days 6-7. From days 8 to 12 the formula was supplemented with rice cereal (133.3 g/L, or 4 g/30 mL formula) and a second complete urine and fecal collection was made on days 11-12. Cereal did not alter fecal nitrogen output or the calculated contribution (45%) of endogenous nitrogen to fecal nitrogen. Cereal did increase nitrogen retention and lower the urinary excretion of the 15N dose (24% of dose). The calculated true digestibility of the rice cereal protein was > 95%. Our results indicate that infants aged 4 mo, in contrast with younger infants, are able to digest and absorb cereal. The addition of cereal to the diet does not lead to increased fecal protein losses.

Absorption of lactose, glucose polymers, or combination in premature infants

STUDY OBJECTIVE

To determine the digestion and absorption of lactose, a combination of lactose and glucose polymers, and glucose polymers alone in infants born at 28 to 42 weeks of gestation.

DESIGN

Each infant received the three carbohydrate solutions (85 gm/L concentration) in random order.

SETTING

Tertiary care urban children's hospital.

INTERVENTIONS

A double-lumen perfusion catheter was placed in the duodenum-jejunum. Absorption was defined as the disappearance of the carbohydrate and all its components (e.g., for lactose: galactose, glucose).

MEASUREMENTS AND MAIN RESULTS

Absorption of lactose was less than that of the lactose-glucose polymer combination and the glucose polymers alone. There was no relationship between lactose absorption and postnatal age, whereas absorption of the lactose-glucose polymer combination and the glucose polymers alone correlated with age. Lactose absorption was not related to the number of days that the infants received full-strength feedings or the total number of days of feeding before the study, whereas absorption of both the lactose-glucose polymer combination and the glucose polymers alone was related to both. Absorption of the three solutions was not related to gestational age or to the number of days before the initial feeding. Lactose absorption was greater in infants who received formula alone than in infants fed formula together with human milk.

CONCLUSIONS

Premature infants do not digest and absorb lactose as well as glucose polymers. However, lactose does not impair the absorption of glucose polymers. Lactose assimilation is not affected by maturation, but the type of diet may affect lactose digestion and absorption. In contrast, digestion and absorption of glucose polymers are related to both postnatal age and diet.

Does the use of hydrochloric acid damage silicone rubber central venous catheters?

BACKGROUND

Hydrochloric acid (HCl) is commonly used to clear obstructions in central venous catheters (CVC).

METHODS

To determine if HCl adversely affects the integrity of a CVC we infused 0.1 N HCl daily into CVC in vitro. At weekly intervals sections of the CVC were removed and examined using scanning electron microscopy.

RESULTS

Over 8 weeks, no damage to the CVC was visible.

CONCLUSIONS

HCl administration poses no threat to the structural integrity of a CVC.

Parenteral nutrient needs of very low birth weight infants

OBJECTIVE

To determine nitrogen and mineral needs in parenterally nourished very low birth weight infants.

DESIGN

Prospective observational study.

SETTING

Neonatal intensive care unit.

PATIENTS

Twenty-four very low birth weight infants (< 1.2 kg) expected to receive parenteral nutrition (PN) exclusively for 3 weeks beginning 3 days after birth.

INTERVENTIONS

Infants received PN solutions according to nursery protocol. Serial 24-hour balance studies were conducted twice weekly. Clinical therapies were tabulated.

MAIN OUTCOME MEASURES

Intake, urinary excretion, and apparent retention of nitrogen, sodium, potassium, zinc, copper, calcium, phosphorus, and magnesium after initiation of PN.

RESULTS

Although urinary K, Zn, Ca, P, and Mg excretion (but not N, Na, and Cu excretion) increased after PN therapy was begun, net nutrient retention increased significantly above baseline for all nutrients. Average weekly nutrient retention was significantly below intrauterine estimates of nutrient accretion for N, Na, Ca, P, and Cu; closely approximated estimates for Zn; and significantly exceeded those for K and Mg. Regression analysis was used to predict parenteral nutrient intakes that would support postnatal nutrient retentions equivalent to the intrauterine estimates. Postnatal therapy with dexamethasone affected N, P, and K excretion and retention.

CONCLUSIONS

Soon after PN administration is begun, positive nutrient balance may be achieved early in the neonatal period. The magnitude of this effect remains uniform during PN administration. Adjustments in parenteral nutrient intake are needed to provide nutrient intakes sufficient to support postnatal retention at rates similar to those of intrauterine accretion. These data should be considered in the design of future studies to determine optimal PN needs of very low birth weight infants.

Jejunal brush border hydrolase activity is higher in tallow-fed pigs than in corn oil-fed pigs

We tested the effect of dietary fat on the lipid composition and hydrolase activity of jejunal brush border membranes in piglets. Eighteen 5-wk-old piglets were divided into three groups and for 4 wk fed either an unsaturated low fat diet (3.2% corn oil), an unsaturated high fat diet (17.2% corn oil) or a saturated high fat diet (2.2% corn oil + 15% tallow). Brush border membranes were prepared from the jejunal mucosa and analyzed for cholesterol, phospholipid and fatty acids. The activities of sucrase-isomaltase, lactase-phlorizin hydrolase, maltase-glucoamylase, aminopeptidase and alkaline phosphatase were measured. Lactase-phlorizin hydrolase isoforms were immunopurified and separated by SDS-PAGE, and their relative proportions were measured by densitometry. The activities of the disaccharidases and alkaline phosphatase, but not aminopeptidase, were greater in animals fed the saturated high fat diet than in animals fed the unsaturated high fat diet. The fatty acid composition of the membranes generally reflected the composition of the diet. Correlation analysis demonstrated that the phospholipid, fatty acid and cholesterol compositions of the membranes were associated with the differences in brush border hydrolase activity.

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.

Supplemental alanylglutamine, organ growth, and nitrogen metabolism in neonatal pigs fed by total parenteral nutrition

The objective of this study was to determine whether supplemental glutamine (alanylglutamine dipeptide) is effective in preventing small intestinal mucosal atrophy associated with total parenteral nutrition and whether it affects the growth of other organs in neonatal pigs. We compared organ growth, intestinal enzyme activity, and plasma nitrogen metabolites in 4-day-old pigs randomly selected to receive total parenteral nutrition supplemented with 0 g, 2.0 g, or 4.5 g of glutamine per deciliter for a total amino acid intake of either 11 or 25 g.kg-1.d-1 for 7 days. Glutamine supplementation increased (60% to 100%) plasma concentrations of glutamine, urea nitrogen, ammonia, and both jejunal villus height and surface area, but it did not significantly affect jejunal mucosal protein and DNA masses or the relative growth of liver, kidneys, and brain. No histologic evidence of tissue toxicity was found. Supplementing large amounts of glutamine (alanylglutamine dipeptide) did not completely prevent total parenteral nutrition-associated intestinal mucosal atrophy but did improve villus morphology without affecting vital organ growth or histology.

Molecular epidemiology of coagulase-negative Staphylococcus blood isolates from neonates with persistent bacteremia and children with central venous catheter infections

Multilocus enzyme electrophoresis was used to genetically characterize sequential isolates of coagulase-negative staphylococci (CONS) from 3 neonates with persistent bacteremia and organisms cultured from several sites in 23 children with presumed catheter-related sepsis (CRS). For 2 of 3 neonates and 21 (91%) of 23 of the patients with presumed CRS, the same CONS clone was isolated from multiple consecutive blood cultures (mean, 7.3 isolates; range, 3-19). For the 23 children with presumed CRS, 7 (30%) had catheter hub (CH) and 7 (30%) had catheter exist site (CES) cultures positive for CONS; cultures from 3 of these patients (from both CH and CES) grew CONS. Genetic analysis of isolates recovered from the CH and peripheral and central venous catheter blood cultures of all 7 patients revealed clonal identity of the strain grown from all sites. In contrast, only 4 (57%) of 7 of the CONS isolates from the CES were the same clone as that isolated from the blood. These data suggest that repetitive isolation of CONS during the course of CRS is due to ongoing bacteremia, not culture contamination with distinct CONS isolates. The results also are consistent with the hypothesis that the CH is a more likely site of initial colonization by CONS than the exist site in patients with CRS.

Bolus versus continuous feedings stimulate small-intestinal growth and development in the newborn pig

Although bolus and continuous tube feedings are common, little is known about their effect on the developing small intestine. To compare their effect on small-intestinal growth and differentiation, six pairs of 3-day-old piglet littermates were randomized to receive similar volumes of sow milk replacer, either by bolus (four times daily, group B) or continuous feedings (over 24 h, group C) for 7 days. The piglets were then killed and small-intestinal length, weight, protein mass, and disaccharidase activities were determined. Small-intestinal mucosal weight and ileal protein mass were greater in group B than in group C (p = 0.0024 and 0.019, respectively). No differences were noted between groups in jejunal mucosal protein mass. Ileal maltase activity also was greater in group B than group C (p = 0.02). Although ileal lactase activity in group B was twice that in group C, the differences did not quite reach statistical significance (p = 0.11). No differences between groups were noted in ileal or jejunal sucrase activity. Our study demonstrated that bolus feedings increased mucosal mass, protein mass, and maltase activity to a greater degree than continuous feedings. These results may have clinical significance for infants receiving long-term tube feedings.

Effect of parenteral calcium and phosphorus therapy on mineral retention and bone mineral content in very low birth weight infants

HYPOTHESIS

If calcium and phosphorus are administered to very low birth weight infants in amounts larger than those currently used in standard parenteral nutrition solutions, apparent retention of calcium and phosphorus (intake minus urinary excretion) will increase and bone mineralization will improve.

DESIGN

Randomized, controlled, double-blind trial.

SETTING

Neonatal intensive care unit.

PATIENTS

Twenty-four very low birth weight infants (< 1.2 kg) expected to receive parenteral nutrition exclusively for approximately 3 weeks beginning 3 days after birth.

INTERVENTIONS

Infants received parenteral nutrition solutions, either the standard mixture containing 1.25 mmol calcium and 1.5 mmol phosphorus per deciliter (group STAND: n = 12, birth weight 921 +/- 171 gm, gestational age 27 +/- 2 weeks (mean +/- SD)) or 1.7 mmol calcium and 2.0 mmol phosphorus per deciliter (group HIGH: n = 12, 857 +/- 180 gm, 27 +/- 2 weeks).

MAIN OUTCOME MEASURES

Intake, urinary excretion, and apparent retention of calcium, phosphorus, and magnesium every 3 days during parenteral nutrition therapy. Serum indexes of mineral status twice during therapy. Bone mineral content of the distal segment of the left radius at 1, 4, 8, and 26 weeks.

RESULTS

Apparent calcium retention (1.2 +/- 0.2 vs 1.6 +/- 0.2 mmol.kg-1.d-1) and phosphorus retention (1.4 +/- 0.2 vs 1.8 +/- 0.4 mmol.kg-1.d-1) differed significantly (p < 0.01) between groups STAND and HIGH, respectively; neither changed with the duration of parenteral nutrition therapy. Serum calcium, magnesium, parathyroid hormone, 25-hydroxyvitamin D, and osteocalcin concentrations were similar in both groups. Serum phosphorus concentration was significantly higher in group HIGH than in group STAND (p = 0.025). The absolute bone mineral content and the rate of increase in bone mineral content between 1 and 4, 1 and 8, and 1 and 26 weeks were significantly greater in group HIGH than in group STAND.

CONCLUSIONS

Increased parenteral intakes of calcium and phosphorus resulted in greater retention of these minerals during parenteral nutrition therapy and in greater bone mineral content after therapy.

Volume of blood required to obtain central venous catheter blood cultures in infants and children

To determine how much blood must be discarded before one can obtain a reliable central venous catheter blood culture, we prospectively cultured the blood (from 96 patients) that is ordinarily discarded before obtaining blood for such a culture. We then compared the prospective culture results with those of the actual blood culture. Three sequentially drawn aliquots of blood were aspirated from the central venous catheter and cultured. The culture results of the second aliquot were comparable to those of the third (the portion usually cultured) in overall sensitivity (94.4%), specificity (94.9%), and positive predictive value (80.9%). Thus, the amount of blood that must be discarded (infants: 0.3 mL; children: 1.0 mL) before one can obtain an accurate central venous catheter culture is less than was previously thought.

The piglet can be used to study the effects of parenteral and enteral nutrition on body composition

Measurement of body composition provides insight into the regulation of normal development as well as the interactions among nutritional, physiological, and biochemical functions. Studies of body composition require an animal model in which body composition at birth and postnatal changes are comparable to those in human infants. Essential to studies of body composition is an animal model that can be fed under various conditions (parenteral and enteral) and can undergo various measurements (whole body and cellular level). The piglet meets these requirements. The postnatal changes in the body composition of infants and piglets are reviewed, and various studies are discussed to show the effect of parenteral and enteral nutrition on piglet body composition. Confirmation of physiological and biochemical similarities in the regulation of body composition in human infants and piglets awaits further study.

Developmental changes in lactase-phlorizin hydrolase precursor isoforms in the rat

The purpose of this study was to determine whether the developmental decline in lactase specific activity (mumol/min/g protein) in the rat was associated with (a) changes in the relative quantities of immunoisolated precursor and mature forms of the enzyme purified by SDS-PAGE and/or (b) immunohistologic changes in the jejunal mucosa. We studied 10- and 16-day-old suckling rat pups, 22-day-old weaned rat pups, and adult female rats (nongravid, pregnant, and lactating). Lactase activity was three- to fourfold higher in 10-day-old pups than in adult rats. Lactase activity was 27% greater in lactating compared with nongravid or pregnant rats. Three molecular forms of the enzyme that migrated identically in all animals were observed on SDS-polyacrylamide gels stained with Coomassie blue: 140-kDa (mature brush border form), 200-kDa, and 220-kDa (apparent precursor forms). There was a striking difference in the proportions of the three polypeptides at different ages that was unrelated to animal status, i.e., pregnant or lactating. As the animals aged, the relative amount of the 140-kDa band declined from 86 +/- 1.1% of the total immunoprecipitated lactase in 10-day old suckling pups to 68 +/- 0.7% in adults. Simultaneously, the relative concentration of the 200-kDa band rose from 1.7 +/- 0.4% in the 10-day-old to 19 +/- 0.6% in adults. The relative concentration of the 220-kDa polypeptide did not change as a function of age.(ABSTRACT TRUNCATED AT 250 WORDS)

Porcine colostrum and milk stimulate visceral organ and skeletal muscle protein synthesis in neonatal piglets

Our objective was to determine the relative contributions of protein synthesis and protein absorption in the rapid accretion of gastrointestinal protein in suckling piglets during the early neonatal period. We measured the rates of tissue protein synthesis using a flooding dose of L-[4-3H]phenylalanine in various visceral and peripheral tissues of neonatal piglets fed water, mature milk or colostrum for 6 h. The jejunal and ileal protein synthesis rates in piglets fed either colostrum or milk were three- to fourfold higher than in piglets fed water. The increased jejunal and ileal protein synthesis could not, however, account for the differences in protein mass between the colostrum-fed and water-fed groups. The relative abundance of IgG, a major porcine colostral protein, in jejunal tissue was markedly higher in piglets fed colostrum than in piglets fed either milk or water. The fractional protein synthesis rates in liver, kidney, spleen and skeletal muscle and the absolute protein synthesis rates in liver and spleen were also greater in piglets fed colostrum than in those fed milk or water. Increased endogenous protein synthesis made only a minor contribution to the increased intestinal protein accretion in neonatal piglets fed colostrum. A much larger proportion of this increase seemed to be a result of absorption and retention of ingested immunoglobulins.

Effect of oral insulin on lactase activity, mRNA, and posttranscriptional processing in the newborn pig

Insulin, found in human and pig colostrum and mature milk, appears to influence small intestinal growth and development. Ileal lactase activity is increased when porcine insulin is added to feedings administered to newborn piglets. We studied 2-day-old miniature piglets to determine whether the increase in lactase activity is accompanied by changes in enterocyte expression of lactase activity, steady-state levels of lactase mRNA, and/or posttranscriptional changes in lactase processing. We randomized the piglets to receive bottle feedings of a swine-weaning milk formula with (group F + I) or without (group F) the addition of 85 mU/ml of regular porcine insulin. The piglets were fed for 6 days (to 8 days of age), after which they were killed and the small intestine removed for analysis. Despite large differences between groups in enterocyte expression of lactase activity in the ileum, no differences were noted in the level of ileal lactase mRNA. The relative proportions of the 207, 210, and 230 kDa precursors of the 160 kDa mature lactase protein were similar between groups. These data indicate that the insulin-induced increased expression of ileal lactase activity is not regulated at the level of its mRNA or at the level of processing of the polypeptide.

Cysteine usage increases the need for acetate in neonates who receive total parenteral nutrition

The addition of cysteine (as cysteine HCl) to a total parenteral nutrition (TPN) solution enhances calcium and phosphate solubility because cysteine lowers the pH of the solution. To determine whether adding cysteine to TPN solutions affected the acid-base homeostasis of infants and increased their need for acetate to obviate acidosis, we studied two groups of neonates--those receiving TPN before (group C) and after (group NC) the addition of cysteine. Measurements were made before and during the first 2 wk of TPN administration. We measured the pH of our standard TPN solution with and without the addition of cysteine. Serum carbon dioxide was significantly lower in group C despite a significantly greater intake of acetate in group NC. In the in vitro study the addition of cysteine to the TPN solution lowered the pH from 5.5 to 5.1. Newborns who received TPN solutions to which cysteine was added had lower serum carbon dioxide values and a greater need to receive acetate than did newborns who received TPN solutions without cysteine.

Total parenteral nutrition energy composition affects small intestinal disaccharidase activity in the newborn miniature pig

Total parenteral nutrition (TPN) decreases disaccharidase activity in the small intestine of humans and miniature piglets. The possibility, however, that specific components of TPN (eg, the energy mix) will increase disaccharidase activity has largely been unexplored. The identification of such components would be particularly useful in the treatment of premature infants with immature gastrointestinal tracts and patients with small intestinal mucosal disease associated with decreased disaccharidase activity. To determine whether the TPN energy composition affects small intestinal disaccharidase activity, 7-day-old miniature piglet littermates were randomized to receive TPN containing either glucose (group G) or glucose and fat (group G/F) as the nonnitrogen energy source(s). The TPN regimens were isonitrogenous and isoenergetic. The piglets were not allowed oral intake during the 7 days they were maintained on TPN. At 14 days of age the piglets were killed and the small intestines analyzed for weight, protein, DNA, and disaccharidase activity. Body weight was similar between groups at both the beginning and end of the study. The TPN regimen did not affect small intestinal weight of protein and DNA content. However, jejunal and ileal sucrase and ileal maltase activities (mumol/min.kg body wt +/- SD) were greater in group G than those in group G/F (28 +/- 9 vs 19 +/- 11, p = 0.04; 13 +/- 7 vs 7 +/- 4, p = 0.037; and 31 +/- 8 vs 19 +/- 10, p = 0.0088, respectively). No differences in lactase activity were noted between groups.(ABSTRACT TRUNCATED AT 250 WORDS)