The use of stable isotope techniques for nutritional and metabolic research in paediatrics

Stable isotope methods are increasingly used in paediatrics for clinical diagnosis and research due to marked improvements in analytical technologies and better availability of suitable tracers. The safety of stable isotopes is of major importance for use in children. Large amounts of deuterium well above the doses applied under clinical conditions may induce adverse effects. In contrast, heavier stable isotopes such as 13C, 15N or 18O do not induce adverse effects even at the highest enrichments obtained, and they are safe. Breath tests with measurements of 13CO2 enrichment after oral application of a tracer can reliably evaluate helicobacter pylori infection and gastric emptying kinetics. Combined with an estimation of total CO2 production, 13CO2 breath tests allow estimation of the absorption and oxidation of 13C-labelled substrates, such as medium- and long-chain triglycerides, and demonstrates the beneficial effect of carnitine supplements on fat oxidation in primary carnitine deficiency. The study of metabolic processes may require the sampling of blood for isotopic analyses of metabolites of the applied tracer. Gas chromatography-isotope ratio mass spectrometry can detect tracer in individual components from small plasma samples. The high precision enabled us to utilize the small differences in natural 13C-enrichment between dietary fats to study fatty acid turnover in term infants, in whom the dietary fat source was switched to corn oil with a slightly higher 13C-content. With this approach we demonstrated active conversion of linoleic into arachidonic acid. We also applied biotechnologically produced, U-13C labelled linoleic and alpha-linolenic acids to infants and detected the conversion of these essential fatty acids to their longer chain polyunsaturated derivatives, with an apparent change of conversion activity with age. Moreover, it has become possible to measure tissue protein synthesis from small biopsy samples obtained in situ without surgery, such as forceps biopsies of rectal tumors. These few examples of recent developments demonstrate the great clinical and scientific potential of stable isotope methods in future paediatric applications.

[Protein-losing giant fold gastritis in childhood--a case report and differentiation from Ménétrier disease of adulthood]

We report on a 2.5-year-old boy, who presented with vomiting since one week and periorbital and pitting edema. Laboratory studies revealed hypoproteinemia and hypoalbuminemia without signs of renal or liver disease. The cause of protein loss was giant fold gastritis disclosed by upper endoscopy. Biopsies revealed foveolar hyperplasia with cystic dilatation of the glands, identical to Ménétrier's disease in adulthood. About 55 cases of hypertrophic gastropathy in children have been published. In contrast to the chronic course of Ménétrier's disease in adults, the pediatric cases are generally benign, self-limited with complete resolution typically within a few weeks. While the etiology of Ménétrier's disease is still unknown, the benign pediatric hypertrophic gastropathies have been associated with infections, primarily CMV and occasionally helicobacter pylori, herpes simplex and mycoplasma. Supportive treatment with a high-protein-diet and intravenous albumin transfusions is recommended. H2-receptor antagonists might improve symptoms.

[Comparison of perforated metal ceiling systems (supported airflow ceilings) with laminar airflow ceilings in type A (DIN 1946 T.4) operating rooms under surgical conditions]

In eleven centrally ventilated operating theatres the concentration of particles and airborne germs in wound vicinity was measured on three workdays. Five theatres were equipped with air supply ceilings with supporting flow outlets (supporting flow ceilings), five with laminar air flow ceilings and one with an air supply ceiling, a body exhaust system and a partition wall between the anesthetic and operating areas. Under routine conditions the air supply of the laminar air flow ceiling with its lower turbulence shielded the operating field from the largely staff-related air contamination in the rest of the theatre better than in the case of the supporting flow ceilings. Particles and airborne germs were removed from the endangered wound area faster. A spatial separation between the anesthetic and the operating areas as well as a body exhaust system lead to a considerable reduction of the contamination. Two theatres were conspicuous by reason of their considerably raised values due to defective control engineering and the wrongly positioning of the operating table. From the point of view of ventilation technique the laminar air flow ceilings with lower turbulence are superior to air supply ceilings with supporting flow outlets in the working day of an operating theatre. In order to minimize the influence of the staff, which up till now has been neglected in testing specifications, constructional possibilities such as the size of ceiling, the partitioning off of operating and anaesthetic areas and the positioning of the operating table in relation to the incoming air should be coordinated rationally. Taking measurements regularly during operations can provide the impulse for considerable improvements in both operational and planning phases.