The usefulness of stable isotopes in nutrition and human health: the application of mass spectrometry and 13C-breath tests to detect helicobacter pylori infection.

The interest in Helicobacter pylori has escalated in recent years. H. pylori may produce a chronic gastric infection which is usually life-long and many epidemiological studies have shown that this is the most common bacterial infection throughout the world involving 50% of the world population. Thus, it is clear that the diagnosis of H. pylori infection represents at least a key step in the management of many of the patients referred to the gastroenterologist. Additionally, due to the wide range and relevance of pathologies possibly related to this infection, from micronutrient malnutrition and co-infections to malignancies, there is the potential for H. pylori to be a major health problem. Improved methods for the diagnosis and follow up treatment of the infection have been developed. Use of stable isotopes as non-invasive and safe diagnostic methods, namely (13C) breath tests, has been the key to a new era of research in H. pylori epidemiology and diagnosis as well as the establishment of eradication therapies. This non-invasive nuclear technique, that is considered the gold standard for the diagnosis of this bacterial infection, has successfully been standardized and implemented along Latin America. Taking into account the high prevalence of this bacterial infection, the impact of this technique in the whole region is very high. In this article we discuss several aspects of this methodology in order to harmonize the application of this method in developing regions.

Nuclear and isotopic techniques applied to supporting nutritional studies in East Asia and Pacific Countries: IAEA's contributions over 20 years.

The world's scientific community has recognized that isotopic techniques play a vital role in monitoring the effectiveness of nutrition intervention by providing precise data on absorption, bioavailablity and interaction of various micronutrients in a cost effective manner. The International Atomic Energy Agency (IAEA) has been supporting many such health related studies in Member States from developing countries using nuclear and isotopic methods for over 20 years. This report documents the Agency's support for a variety of projects in East Asia and Pacific countries to assess body composition, total energy expenditure, nutrient intake, osteoporosis, infection, vitamin and mineral bioavailability as well as food composition. The IAEA spent a total of 10,302,356 US dollars through Coordinated Research Projects (CRP) and Technical Cooperation Projects (TCP) over the past 20 years. Out of this only 2,732,802, US dollars or 26.5% was used by the East Asia and Pacific countries. While the participation of East Asia and Pacific countries was strong in CRPs and moderate in regional TCPs, they did not participate in national TCPs at all. The non-participation under national TCPs is a serious deficiency when compared with Latin American and African regions and therefore, more participation from the East Asia and Pacific countries in national TCPs is strongly encouraged in the future.

Diet does not ensure normal development in galactosemia.

This review deals with the treatment of inherited classical galactosemia by a lactose-free diet. Although, with dietary treatment, there is a remarkable improvement in the acute phase of the disease, the long-term outcome has been disappointing for most patients, especially regarding the central nervous system and ovarian dysfunction in females. There is a need for new approaches to treatment, in combination with diet therapy, that could improve the outcome of patients with galactosemia.

Iron status and iron supplementation in children with classical phenylketonuria.

Iron (Fe) status and Fe supplementation were assessed in 20 children with phenylketonuria (PKU) through dietary intake and through measurements of ferritin, hematocrit, hemoglobin, mean cellular hemoglobin, mean cellular volume, serum Fe, total iron binding capacity, unbounded iron binding capacity, transferrin saturation and transferrin. Findings were compared to reference values and to data from age-matched controls. The prescribed phenylalanine-restricted diet supplied all the recommended nutrients. Dietary Fe was present in the diets, but its bioavailability is questionable as several laboratory results were not within accepted reference values. A ferrous sulphate supplement (5 mg elemental Fe/kg daily) was given for 120 days to a group of PKU children with lower Fe parameters, thus changing some of the parameters studied. Serum ferritin (p < 0.1), transferrin saturation and serum Fe (p < 0.05) increased after the treatment. The need for improved diagnosis of Fe status and determination of whether PKU children can benefit from therapeutic Fe is discussed.

Enhancing activity of rat tissue extracts for induction of lambda prophage by L-azaserine.

We studied the effect of rat tissue extracts on induction of lambda prophage in Escherichia coli (lambda) by L-azaserine. Hepatic and pancreatic extracts, primarily the cytosolic fraction, markedly increased the rate of induction. Hepatic extracts from lipotrope-deficient rats were somewhat more active than extracts from normal rats. The enhancing activity in normal rat hepatic cytosol was partially characterized. It reduced by about one-half the dose of azaserine required for a given purpose. The enhancement was increased by preincubating the bacterial cells with cytosol; cells retained the effect after cytosol was removed. Enhancing activity was inhibited strongly by the amino acids phenylalanine, tryptophan, and tyrosine; to lesser extents by leucine, methionine, and serine; and not at all by proline or glutamine. It was eliminated by dialysis of the cytosol and reduced by omission of nicotinamide adenine dinucleotide phosphate (NADP) from the reaction mixture. Heating the cytosol to 60 degrees C or 80 degrees C or varying the pH of the reaction mixture from 6 to 8 had no significant effect. Treating the cytosol with trypsin appeared to release an inhibitor of the activity. Glutathione, cysteine, and beta-mercaptoethanol also enhanced lambda induction by azaserine, but the cytosolic activity was not affected by the thiol-inactivating compound diethylmaleate (DEM). The results suggest that factors in cytosol interact with bacterial cells to facilitate transport of azaserine into the cells, primarily through the aromatic amino acid transport system. A small molecule, not a free thiol compound, appears to be involved. It may serve to establish reducing conditions protective for azaserine, the probable mechanism of action of sulfhydryl compounds.

Nuclear and isotopic techniques application used in supporting nutritional studies in Latin America countries

La comunidad global de la nutrición reconoce la utilidad de técnicas nucleares e isotópicas y especialmente de isótopos estables para las medidas exactas en las áreas dominantes de la nutrición humana y de la salud. Aunque se ha progresado en muchos países de América Latina en la reducción el número absoluto de desnutridos, la política alimentaria y las comunidades de la salud pública, tienen que hacer frente a la carga doble en la salud. Por un lado se tiene que tratar la prevención de la obesidad y, por otro lado, se está intentando reducir la malnutrición y la pobreza. Para ésto, el conocimiento científico relevante y el arte de la práctica son necesarios para ser acertados en el desarrollo de los programas sostenibles de la nutrición. Los objetivos de esta revisión son destacar el papel de técnicas isotópicas en estudios nutricionales y revisar el papel del Organismo Internacional de Energía Atómica (OIEA) en la intervención y soporte del estado de la nutrición en los países de América Latina