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J H Hoekstra

Publications and source records attributed to J H Hoekstra.

At least 37 records · Page 2Linked to original sources
PubMed1996

Molecular analysis of the fructose transporter gene (GLUT5) in isolated fructose malabsorption.

Fructose, a naturally occurring monosaccharide, is increasingly used as an added sweetener in processed foods in the form of high fructose corn syrup. Increased fructose intake combined with the identification of children with clinical evidence of isolated fructose malabsorption (IFM) has stimulated interest in possible disorders of fructose absorption. The intestinal absorption of fructose is carried out by the facilitative hexose transporter, which has been designated as GLUT5. Functional properties and tissue distribution of GLUT5 suggest that IFM might be due to mutations in the GLUT5 gene. To test this hypothesis, we screened the GLUT5 gene for mutations in a group of eight patients with IFM and in one subject with global malabsorption, as compared with 15 healthy parents of subjects and up to 6 unrelated controls. No mutations were found in the protein coding region of this gene in any of the subjects. A single G to A substitution in the 5' untranslated region of exon 1 was identified in the subject with global malabsorption. This subject and her healthy mother were heterozygous for the variant sequence, suggesting that it was unlikely to be clinically significant. In addition, sequence analysis of each of the 12 GLUT5 exons was performed in the index case and confirmed the negative single-strand conformation polymorphism findings. These studies demonstrate that IFM does not result from the expression of mutant GLUT5 protein.

Alleles↗
PubMed1996

[Infant diarrhea].

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Child, Preschool↗
PubMed1996

Evaluation of 13CO2 breath tests for the detection of fructose malabsorption.

Breath hydrogen (H2) studies have made clear that small intestinal absorption of fructose is limited, especially in toddlers. Malabsorption of fructose may be a cause of recurrent abdominal pain and chronic nonspecific diarrhea (toddler's diarrhea). Fructose absorption is facilitated by equimolar doses of glucose and, as we have found, amino acids (especially L-alanine); the mechanism underlying this effect remains unclear. To study fructose absorption in a more direct way, we combined breath H2 studies with breath 13CO2 studies. Gastric emptying was studied by using L-glycine-1-13C in 4 children from 12.1 to 16.0 years of age. After 25 gm of fructose and 27.5 gm of glucose, when given together, gastric emptying was significantly (p<0.05) slower than with either sugar alone. In a second series of experiments, 5 children from 12.0 to 15.9 years of age were tested with 25 gm of fructose, alone and with equimolar doses of glucose and L-alanine, and 4 younger children from 3.1 to 6.1 years of age were tested with 2 gm/kg (max 37.5 gm) fructose, alone or with an equimolar dose of L-alanine. All fructose solutions were enriched with 15 mg of D-fructose-13C-6. In all 9 children, fructose was malabsorbed as judged by breath H2 increases > or = 20 ppm, and the addition of glucose or L-alanine resulted in significantly lower breath H2 increases (p < or = 0.005 for glucose, p < or = 0.001 for alanine). In contrast, the addition of alanine or glucose did not change the pattern of breath 13CO2 excretion in the 5 older children, whereas in the 4 younger children (with relatively higher doses), L-alanine addition resulted in significantly lower increases in breath 13CO2. In the latter group, for each time point, breath H2 and 13CO2 concentrations after fructose were compared with those after fructose plus L-alanine; in 20 out of 24 points, both H2 and 13CO2 were higher after fructose. These results suggest that 13CO2 not only originated from the oxidation of absorbed substrate but also, at least in part, from colonic bacterial metabolism. For the detection of [correction of or] fructose malabsorption--as opposed to, for instance, lactose--the 13CO2 breath test seems to be of limited value.

Adolescent↗
PubMed1996

Chronic nonspecific diarrhea of childhood: pathophysiology and management.

Chronic nonspecific diarrhea, or toddler's diarrhea, is a frequently encountered disorder of defecation in otherwise healthy children. Although the precise pathophysiology remains to be elucidated, evidence suggests that toddler's diarrhea primarily is a gut motility disorder, modulated by dietary factors. Although the role of low-fat diets has since long been established, the liberal consumption of fruit juices and soft drinks is considered an equally important factor. Normalization of the child's diet, especially with regard to fat, fiber, fluids, and fruit juices, usually suffices to attain resolution of the diarrhea.

Child Nutritional Physiological Phenomena↗
PubMed1996

Facilitating effect of amino acids on fructose and sorbitol absorption in children.

The facilitating effect of glucose on free fructose absorption has been suggested to be due to a sucrase-related transport mechanism. In contrast, the conditions influencing the absorption of sorbitol have hardly been investigated. As amino acids promote transcellular water flow, we investigated their effects on the absorption of fructose and sorbitol. We studied 15 healthy children using breath hydrogen tests following the ingestion of fructose and sorbitol, alone and in combination with glucose or amino acids. Similarly, the effect of acarbose pretreatment on sucrose and fructose-glucose absorption was investigated. The inhibition of sucrase isomaltase by acarbose impedes the absorption of sucrose but not of the fructose-glucose mixture. Fructose absorption is enhanced by glucose and by the amino acids L-alanine, L-glutamine, L-phenylalanine, and L-proline. Similarly, the absorption of sorbitol is facilitated by glucose and L-alanine. These results are not in concordance with a sucrase-related fructose-transport system and suggest another mechanism for glucose-induced enhancement of fructose (and sorbitol) absorption. We hypothesize that the absorption of fructose and sorbitol may be stimulated by the increased water flux induced by active absorption of glucose as well as amino acids.

Adolescent↗
PubMed1995

Fructose breath hydrogen tests in infants with chronic non-specific diarrhoea.

UNLABELLED: Clear fluids high in fructose (e.g., apple juice) have been incriminated for symptoms of chronic non-specific diarrhoea (CNSD), in particular in children 1-4 years of age. H2 breath tests were performed, after ingestion of fructose (1 g/kg), in 15 patients referred with CNSD and 35 controls. All 15 CNSD children (100%) had breath peak H2 of > or = 20 ppm versus 49% of the 35 controls (P = 0.0005). Median peak H2 in CNSD (90 ppm, range 31-136) was significantly higher than in controls (20 ppm, range 1-139) (P < 0.001). Orocoecal transit time in children with positive tests was similar in both groups. Similarly, median H2 increases during the test period had the same distribution. We demonstrated fructose malabsorption in CNSD, but found a great overlap with the control group. Our results strongly discourage the use of fructose breath H2 tests in children suspected of CNSD. A positive test has no diagnostic value and a negative test has no clinical implications. CONCLUSION: For clinical practice, we suggest a dietary history and a trial of appropriate measures in infants with chronic nonspecific diarrhoea, instead of performing the fructose H2 breath test.

Beverages↗
PubMed1995

Fruit juice malabsorption: not only fructose.

Malabsorption of free fructose, when ingested in excess over glucose, is considered a significant factor in apple juice induced diarrhoea. Absorption of the carbohydrates in fruit juices was investigated by means of the hydrogen breath test in 15 healthy children aged 2.2-6.4 years, consuming 15 ml kg-1 of each juice with a maximum of 375 ml. Incomplete absorption was found following the ingestion of apple juice (5/5), grape juice (10/10) and bilberry juice (8/10), although the last two contain equivalent concentrations of fructose and glucose. When the same tests were repeated after yeast treatment of the juices, which leads to major reductions in fructose and glucose contents, malabsorption was found to persist. No symptoms were observed following any of the tests. Our results suggest a significant role for other carbohydrates than fructose, possibly those originating from the fruit skin, with respect to fruit juice-induced breath hydrogen excretion.

Breath Tests↗
PubMed1995

Fluid intake and industrial processing in apple juice induced chronic non-specific diarrhoea.

Dietary factors have been shown to contribute to the occurrence or persistence of chronic non-specific diarrhoea (CNSD). Among these are low dietary fat, high fluid consumption, and the consumption of apple juice. Prompted by the clinical impression that freshly pressed and unprocessed ('cloudy') apple juice was less likely to induce diarrhoea than normal, enzymatically processed ('clear') apple juice, both juices were compared in terms of carbohydrate malabsorption, gastric emptying, and effects on defecation patterns. Clear and cloudy apple juice differ in their fibre and non-absorbable monosaccharide and oligosaccharide contents. Ten healthy children aged 3.6 to 5.9 years ingested 10 ml/kg of clear and cloudy apple juice; in five of them it was enriched with 40 mg of [1-13C]-glycine. Clear apple juice resulted in increased (> or = 20 ppm) breath hydrogen excretion in 8/10, compared with 5/10 after cloudy apple juice; peak breath hydrogen was higher in the clear apple juice group (35 (4) and 18 (3) ppm, respectively). Gastric emptying as determined by means of labelled breath carbon dioxide (13CO2) excretion was similar with both juices. In a four week crossover clinical trial 12 children, formerly diagnosed as having CNSD, were given extra clear fluids (excluding fruit juices; > or = 50% over basal consumption), clear apple juice, or cloudy apple juice, for five day periods. Extra fluids and cloudy apple juice did not influence stool frequency and consistency compared with the basal period. In contrast, clear apple juice significantly promoted diarrhoea. It is suggested that, in addition to fructose, the increased availability of non-absorbable monosaccharides and oligosaccharides as a result of the enzymatic processing of apple pulp is an important aetiological factor in apple juice induced CNSD.

Breath Tests↗
PubMed1993

Apple juice malabsorption: fructose or sorbitol?

Carbohydrate malabsorption after apple juice ingestion may produce abdominal symptoms and diarrhea, especially in children. The carbohydrates suggested to play roles in this process are fructose, as it is present in excess of glucose, and sorbitol. Absorption of the carbohydrates in apple juice was investigated in 17 children and 12 adults by means of the hydrogen breath test. Apple juice was given at a dose of 15 ml/kg body weight, with a maximum of 375 ml. Fructose (0.6 g/kg) and sorbitol (0.06 g/kg), alone and in combination, were administered in amounts similar to their contents in apple juice (fructose as excess over glucose content). Apple juice malabsorption, as judged by a peak breath H2 excretion of > or = 20 ppm, was found in 11 children (65%) and 4 adults (33%). Of those malabsorbing apple juice, 7 of 11 children malabsorbed fructose, 1 of 11 sorbitol, and 4 of 11 the combination; the four adults absorbed all test solutions completely. We could not find an additive effect of sorbitol on breath H2 excretion after fructose ingestion. Peak breath H2 concentrations after apple juice ingestion (mean +/- SEM: 43 +/- 7 ppm) were higher than those with fructose (23 +/- 5 ppm; p < 0.05) or the fructose-sorbitol combination (20 +/- 5 ppm; p < 0.05). Fructose, and not sorbitol, is the sugar responsible for the increase in breath H2 after apple juice consumption and therefore for the diarrhea accompanying excessive apple juice consumption in toddlers.

Adult↗
PubMed1993

Fructose breath hydrogen tests.

Fructose absorption was studied by the breath hydrogen test in 114 healthy children aged 0.1-6 years, given either 2 g/kg or 1 g/kg of fructose. All 57 children given 2 g/kg had peak breath hydrogen excretions > or = 20 ppm. At 1 g/kg only 25/57 (44%) showed incomplete absorption and the percentage incompletely absorbing fructose and the peak breath hydrogen value were significantly higher in children aged 1-3 years. Interestingly, this age distribution correlates with that of toddler diarrhoea.

Breath Tests↗
PubMed1992

[A newborn infant with a tail].

A case of a male baby with a tail is described. The tail was surgically removed. Histopathological investigation showed that it was covered with hairless skin. It contained adipose and fibrous tissue, arteries, veins and nerves, but no cartilage, bone or muscle. In most cases of these caudal appendages surgical excision is sufficient, although an underlying anomaly should be excluded radiographically.

Congenital Abnormalities↗
PubMed1992

[Intraosseous infusions in children].

Tibial intraosseous infusions can be invaluable in the management of the pediatric patient who is in cardiac arrest or severe shock when vascular access by the intravenous route is unattainable. Recently there has been renewed interest in this procedure. There is a small risk of complications.

Child, Preschool↗