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In patients with phenylketonuria (PKU), extra tyrosine supplementation is advocated in addition to tyrosine enriched amino acid mixtures. PKU patients have low fasting plasma tyrosine concentrations, but little is known about tyrosine fluctuations during the day. Plasma tyrosine concentrations were studied in 12 PKU patients in response to a test without breakfast and to three tests with different tyrosine contents in breakfast and lunch: 0%/30%, 25%/30%, 50%/10%, and 75%/10% tests, reflecting the protein consumption at breakfast and lunch, respectively. Prolonged fasting resulted in a small decrease in the already low overnight fasting plasma tyrosine concentrations. Breakfast and lunch with 25% and 30% of the daily tyrosine intake resulted in both lower than normal and higher than normal tyrosine concentrations. The 50%/10% and 75%/10% tests resulted in excessively high plasma tyrosine concentrations in most patients. Therefore, both lower than normal and higher than normal postprandial plasma tyrosine concentrations were found in treated PKU patients, even if the daily tyrosine intake was distributed evenly. When there was a large fractional tyrosine intake from one meal, very high plasma tyrosine concentrations were found. Therefore, strict control of plasma tyrosine is necessary if tyrosine supplementation is considered in addition to the tyrosine-enriched amino acid mixtures. (c) 1996 American Society for Clinical Nutrition [ABSTRACT FROM AUTHOR]

Encopresis is often the result of chronic constipation in the majority of paediatric patients. In clinical practice, however, encopresis is also seen without constipation and it is unknown whether these two clinical variants are based on similar or different pathophysiological mechanisms, requiring different therapeutic approaches. We analysed clinical symptoms, colonic transit time (CTT), orocaecal transit time (OCTT), anorectal manometric profiles, and behavioural scores. Patients were divided into two groups, one consisted of 111 children with paediatric constipation, and another group of 50 children with encopresis and/or soiling without constipation. Significant clinical differences in children with encopresis/soiling existed compared with children with paediatric constipation regarding: bowel movements per week, the number of daytime soiling episodes, the presence of night time soiling, the presence and number of encopresis episodes, normal stools, pain during defecation, abdominal pain, and good appetite. Total and segmental CTT were significantly prolonged in paediatric constipation compared with encopresis/soiling, 62.4 (3.6-384) and 40.2 (10.8-104.4) hours, respectively. No significant differences were found in OCTT. Among the two groups, all manometric parameters were comparable, except for a significantly higher threshold of sensation in children with paediatric constipation. The defecation dynamics were abnormal in 59% and 46% in paediatric constipation and encopresis/soiling, respectively, and were significantly different from controls. Using the child behaviour checklist no significant differences were found when comparing children with paediatric constipation and encopresis/soiling, while both patient groups differed significantly from controls. In conclusion, our findings support the concept of the existence of encopresis as a distinct entity in children with defecation disorders. Identification of such children is based on clinical symptoms, that is, normal defecation frequency, absence of abdominal or rectal palpable mass, in combination with normal marker studies and normal anal manometric threshold of sensation, Thus, encopresis is not always the result of constipation and can be the only clinical presentation of a defecation disorder. [ABSTRACT FROM AUTHOR]

Objective: To determine the relation between intestinal permeability and birth weight, gestational age, postnatal age, and perinatal risk factors in neonates.Study Design: Intestinal permeability was measured by the sugar absorption test within two days of birth and three to six days later in preterm and healthy term infants. In the sugar absorption test, the urinary lactulose/mannitol ratio is measured after oral ingestion of a solution (375 mosm) of lactulose and mannitol.Results: A first sugar absorption test was performed in 116 preterm (26-36 weeks gestation) and 16 term infants. A second test was performed in 102 preterm and nine term infants. In the preterm infants, the lactulose/mannitol ratio was not related to gestational age (r = -0.09, p = 0.32) or birth weight (r = 0.07, p = 0.43). The median lactulose/mannitol ratio was higher if measured less than two days after birth than when measured three to six days later (0.427 and 0.182 respectively, p<0.001). The lactulose/mannitol ratio was higher in preterm infants than term infants if measured within the first 2 days of life (0.404 and 0.170 respectively, p < 0.001), but not different three to six days later (0.182 and 0.123 respectively, p = 0.08). In multiple regression analysis of perinatal risk factors, only umbilical arterial pH correlated with the lactulose/mannitol ratio in preterm infants less than 2 days of age (T = -1.98, p = 0.05).Conclusions: In preterm infants (26-36 weeks gestation), intestinal permeability is not related to gestational age or birth weight but is higher during the first 2 days of life than three to six days later. It is higher in preterm infants than in healthy term infants only if measured within two days of birth. This suggests rapid postnatal adaptation of the small intestine in preterm infants. [ABSTRACT FROM AUTHOR]