Deeper rectal biopsies and better yield of neuronal structures with Scheye vs Noblett forceps--preliminary results.

OBJECTIVE: The aim of the study was to compare 2 different forceps designed to perform biopsies of the rectal mucosa, those of Noblett and Scheye, the latter having a similar design and differing by the disposable cutting system. METHODS: This historical study compares biopsies obtained with the Noblett forceps in 13 girls and 20 boys (mean ± SD age, 13 ± 30 months) and biopsies obtained with the Scheye forceps in 19 girls and 21 boys (mean ± SD age, 8.5 ± 19 months). RESULTS: The thickness of the material obtained with the Scheye forceps was significantly greater for the specimens obtained with the Scheye forceps (total biopsy: 1.74 ± 0.46 mm vs 0.67 ± 0.2 mm, P < .0001; submucosa: 1.12 ± 0.4 mm vs 0.14 ± 0.17 mm, P < .001). The Scheye forceps considerably increased the yield of neuronal structures, both for submucosal plexus (P < .003) and ganglia (P < .0001). No complication occurred in either group. CONCLUSION: The Scheye disposable rectal biopsy system provides larger mucosal biopsy samples than the Noblett with increased recovery of neuronal structures.

Evolution of fat oxidation during exercise in obese pubertal boys: clinical implications.

In this study, we examined fat oxidation rates during exercise in obese pubescent boys. Three groups of pubescent boys (16 pre-pubescent, Tanner's stage I; 16 pubescent, Tanner's stage III; and 14 post-pubescent, Tanner's stage V) performed a graded test on a leg cycle ergometer. The first step of the test was fixed at 30 W and power was gradually increased by 20 W every 3.5 min. Oxygen consumption (VO(2)) and carbon dioxide production (VCO(2)) were determined as the means of measurements during the last 30 s of each step, which allowed us to calculate fat oxidation rates versus exercise intensity. Between 20 and 50% of peak oxygen consumption (VO(2peak)), fat oxidation rate in relative values (mg . min(-1) . kg FFM(-1)) decreased continuously with pubertal development. In the same way, the maximum rate of fat oxidation occurred at a lower percentage of VO(2peak) (pre-pubescent: 49.47 +/- 1.62%; pubescent: 47.43 +/- 1.26%; post-pubescent: 45.00 +/- 0.97%). Our results confirm that puberty is responsible for a decrease in fat free mass capacities to use fat during exercise. The results suggest that post-pubescent obese boys need to practise physical activity at a lower intensity than pre-pubescent boys to enhance lipolysis and diminish adipose tissue and the consequences of obesity.

Lead and aluminium levels in infants' hair, diet, and the local environment in the Moroccan city of Marrakech.

In order to assess the contamination burden of infants from the city of Marrakech (Morocco), hair lead and aluminium concentrations were studied in a sample of 573 infants, aged 0 to 12 months, and correlated with the infants descriptors such as age, gender and the parents occupations. Moreover, the two metals were measured in the local environment (soil, drinking water) and in the food commonly used during weaning. The mean values in children's hair are 6.6 and 9.5 microg/g for lead and aluminium respectively. The higher value for aluminium compared with lead can be explained by the higher levels of aluminium available in both the infant food and the environment. Age, gender, and the parents' occupations influenced significantly lead but not aluminium contents.

[Effects of puberty on glucose-lipid balance during exercise in the obese child]. / Effets de la puberté sur la balance glucido-lipidique lors de l'exercice de l'enfant obèse.

The aim of the present study was to investigate effect of puberty on substrate oxidation rates using a graded exercise test to exhaustion. Two groups of obese adolescent males (34 prepubertal: body mass index (BMI) = 25,94 +/- 2,63; Z-score = 4,43 +/- 1,83; and 26 postpubertal: BMI = 31,14 +/- 4,88; Z-score = 5,264 +/- 1,76) performed an exercise test on a cycle ergometer. The test consisted in a series of graded exercises on a cycle ergometer. Stage duration was 3 min 30 s. Fat and carbohydrate rates were calculated during the last 30 s of each stage using stoichiometric equations, and this permitted us to calculate substrate oxidation according to exercise intensity. Lipid oxidation rates are significantly higher in the postpubertal group. When the fat oxidation rates are reported relative to fat free mass, fat oxidation rates are higher in the prepubertal group. Puberty decreases significantly the capacity of fat free mass to oxidize fat for a same level of exercise.

Iron and exercise induced alterations in antioxidant status. Protection by dietary milk proteins.

Lipid peroxidation stress induced by iron supplementation can contribute to the induction of gut lesions. Intensive sports lead to ischemia reperfusion, which increases free radical production. Athletes frequently use heavy iron supplementation, whose effects are unknown. On the other hand, milk proteins have in vitro antioxidant properties, which could counteract these potential side effects. The main aims of the study were: (1) to demonstrate the effects of combined exercise training (ET) and iron overload on antioxidant status; (2) to assess the protective properties of casein in vivo; (3) to study the mechanisms involved in an in vitro model. Antioxidant status was assessed by measuring the activity of antioxidant enzymes (superoxide dismutase (SOD); glutathione peroxidase (GSH-Px)), and on the onset of aberrant crypts (AC) in colon, which can be induced by lipid peroxidation. At day 30, all ET animals showed an increase in the activity of antioxidant enzymes, in iron concentration in colon mucosa and liver and in the number of AC compared to untrained rats. It was found that Casein's milk protein supplementation significantly reduced these parameters. Additional information on protective effect of casein was provided by measuring the extent of TBARS formation during iron/ascorbate-induced oxidation of liposomes. Free casein and casein bound to iron were found to significantly reduce iron-induced lipid peroxidation. The results of the overall study suggest that Iron supplementation during intensive sport training would decrease anti-oxidant status. Dietary milk protein supplementation could at least partly prevent occurrence of deleterious effects to tissue induced by iron overload.

Colonic response to food in constipation.

OBJECTIVES: Colonic response to food is possibly abnormal in constipation. METHODS: The colonic response to food was evaluated in 323 patients and 60 healthy subjects by following the movements of radiopaque markers after ingestion of a standard 1,000-cal test meal. Constipated patients were divided into four groups: one with a normal, and three with a delayed colorectal transit time. When the delay was found mainly in the ascending colon, the group was labeled as suffering from "colonic inertia". In "hindgut dysfunction", the delay was predominantly found in the descending colon, whereas the term "outlet obstruction" was reserved for constipated patients whose major site of delay was the rectosigmoid area. Colonic response to food was quantified by evaluating the variation of markers in a given abdominal region and the evolution of the geometric center on the entire plain film of the abdomen. RESULTS: Emptying of the caecum-ascending colon and filling of the rectosigmoid area characterize the colonic response to food in healthy subjects. Constipated patients also filled the rectosigmoid, but different patterns were found in the colon. In constipated patients with transit in the normal range, there was a frequent (41%) absence of colonic response to food as compared to controls (13%) and constipated patients with delayed transit (p<0.0001). The response to food of patients with colonic inertia was similar to that of healthy subjects in terms of distal progression, but less marked. The hindgut dysfunction group emptied the entire left colon but failed to empty the caecum and ascending colon. In the outlet obstruction group, there was no distal progress of the geometric center after meal. CONCLUSIONS: Abnormal colonic response to food is frequently found in constipated patients, with different patterns according to the type of constipation.

Milk proteins and iron absorption: contrasting effects of different caseinophosphopeptides.

Clusters of phosphoserine residues in cow milk caseins bind iron (Fe) with high affinity. Casein inhibits Fe absorption in humans, but protein hydrolysis lessens this effect. Phosphopeptides from different caseins gave conflicting results on Fe absorption; release of phosphate residues by intestinal alkaline phosphatase could be a key point of that metabolism. The objectives of this study were to compare the absorption of Fe complexed to caseinophosphopeptides (CPP) of the main cow milk caseins beta-casein (beta-CPP) and alpha(s)-caseins (alpha(s1)-CPP) and to assess the role of alkaline phosphatase on this absorption. Two experimental models were used: an in vivo perfused rat intestinal loop and an in vitro Caco-2 cell culture model. In addition, we determined the effect of an intestinal phosphatase inhibitor on these various forms of Fe. Gluconate Fe was used as control. In both models, uptake and net absorption of Fe complexed to CPP from alpha(S1)-caseins were significantly lower than from Fe complexed to beta-CPP. Inhibition of the intestinal phosphatase significantly increased the uptake and the absorption of Fe complexed to beta-CPP without effect on the other forms of Fe. These results confirm the enhancing effect of beta-casein and its CPP on Fe absorption. The differences between CPP could be explained by their structural and/or conformational features: binding Fe to alpha(S1)-CPP could impair access to digestive enzymes, whereas beta-CPP-bound Fe is better absorbed than its free form. The differences in protein composition between cow and breast milk, which does not contain alpha-casein, could explain some of their differences in Fe bioavailability.

Improved absorption of caseinophosphopeptide-bound iron: role of alkaline phosphatase.

Hydrolysis of proteins could lessen their inhibiting effect on the poor absorption of cow's milk iron (Fe), which is responsible for the high incidence of Fe deficiency worldwide. When bound to Fe, caseinophosphopeptides (CPP) derived from milk proteins resist luminal digestion, enhance Fe solubility and could improve its bioavailability; brush border enzyme alkaline phosphatase activity could influence iron absorption by releasing free Fe; this study assessed its role in the absorption of CPP-bound Fe. Rat duodenal loops were perfused with Fe gluconate or Fe bound to the CPP of beta casein [beta-CN (1-25)], with or without the addition of an inhibitor of alkaline phosphatase, Na2WO4. The uptake of Fe-beta-CN (1-25) was greater than Fe gluconate. Na2WO4 enhanced the uptake of Fe-beta-CN (1-25) and not of Fe gluconate. So the release of free, insoluble Fe, by alkaline phosphatase seems to be prevented by providing Fe in the Fe-beta-CN (1-25) complex form. Its good disappearance rate makes beta-CN (1-25)-bound Fe a candidate for food fortification.

Iron absorption from concentrated hemoglobin hydrolysate by rat.

Although heme iron is highly bioavailable, the low iron content of hemoglobin prevents its use for dietary fortification; on the other hand, purified heme has low solubility and absorption rate. The present study was designed to assess the interactions between concentrated heme iron and peptides released during globin hydrolysis and cysteine and their relation with iron absorption. Hemoglobin was hydrolyzed by pepsin or subtilisin, and then, heme iron was concentrated by ultrafiltration. Iron absorption was studied in a Ussing chamber; gluconate was used as control. Iron uptake from nonconcentrated pepsin hydrolysate and gluconate was lower than from other groups. Cysteine significantly enhanced iron uptake except from the concentrated subtilisin hydrolysate. There was no significant difference between cysteine-supplemented groups. According to the different hydrolysis pathways of enzymes, it is assumed that the presence of hydrophobic peptides and the strength of heme-peptide interactions are both determining factors of heme iron absorption. These interactions occur mainly before iron uptake, as emphasized by the effect of cysteine.

Influence of various phosphopeptides of caseins on iron absorption.

The influence of the origin and kind of caseinophosphopeptide (CPP) on iron absorption was assessed by comparing a commercially available CPP mixture (CPPs) and derived chromatographic fractions with the purified, chemically phosphopeptide of beta-casein [beta-CN(1-25)] using a perfused rat duodenal loop system; gluconate iron was used as control. Only iron complexed to beta-CN(1-25) displayed a better bioavailability than gluconate iron. The results obtained with various chromatographic fractions indicated that phosphopeptides of different origins (alpha(s)- versus beta-caseins) display specific effects. These findings contribute to the explanation of the discrepancy about the role of caseinophosphopeptides on mineral bioavailability in vivo.

Bioavailability of caseinophosphopeptide-bound iron.

Iron deficiency, one of the main worldwide nutritional deficiencies, results from the low bioavailability of most dietary iron, including cow milk. Hydrolysis of the cow milk protein casein produces low molecular weight caseinophosphopeptides (CPPs). Binding of iron to CPPs keeps it soluble in the digestive tract and prevents the formation of high molecular weight ferric hydroxides, which are poorly absorbed. Previous experimental studies have shown that iron bound to the phosphopeptide containing the first 25 amino acids of beta-casein, or beta-CN (1-25), is well absorbed and corrects efficiently iron deficiency. We sought to assess in vivo iron absorption and uptake by tissues involved in iron metabolism and storage (liver, spleen, bone marrow), using radiolabeled iron. beta-CN (1-25)-Fe displayed better absorption and tissue uptake by the vascularized rat loop model compared with a control substance, ferric ascorbate. The metabolism of beta-CN (1-25)-Fe labeled with iron 59, added to cow milk, was also studied in young women. Although the absorption of beta-CN (1-25)-Fe was not significantly higher than that of ferrous sulfate, it displayed significantly higher tissue uptake. This increase was transient and had disappeared by the 14th day of the study, suggesting that iron was used for metabolic purposes.

Influence of the extent of hemoglobin hydrolysis on the digestive absorption of heme iron. An in vitro study.

This study was designed to assess the interactions of heme with peptides produced by enzyme hydrolysis of hemoglobin, and their relationship with heme iron absorption. Bovine hemoglobin was hydrolyzed by pepsin or by subtilisin, which differ in their hydrolysis processes. The hydrolysis rate ranged from 0 (native hemoglobin) to 15%. Heme solubility and heme-peptides interactions were compared to iron absorption by the Ussing chamber model, at intestinal pH (7.5). Increasing hemoglobin hydrolysis enhanced iron absorption; the highest value was reached between 8 and 11% hydrolysis, whatever the enzyme used. Comparing the products of hydrolysis of the two enzymes showed that heme iron absorption depends not only on its solubility, but relies mainly on the balance between the strength of heme-peptides and the polymerization rate of heme.