Smart single-chip gas sensor microsystem.

Research activity in chemical gas sensing is currently directed towards the search for highly selective (bio)chemical layer materials, and to the design of arrays consisting of different partially selective sensors that permit subsequent pattern recognition and multi-component analysis. Simultaneous use of various transduction platforms has been demonstrated, and the rapid development of integrated-circuit technology has facilitated the fabrication of planar chemical sensors and sensors based on three-dimensional microelectromechanical systems. Complementary metal-oxide silicon processes have previously been used to develop gas sensors based on metal oxides and acoustic-wave-based sensor devices. Here we combine several of these developments to fabricate a smart single-chip chemical microsensor system that incorporates three different transducers (mass-sensitive, capacitive and calorimetric), all of which rely on sensitive polymeric layers to detect airborne volatile organic compounds. Full integration of the microelectronic and micromechanical components on one chip permits control and monitoring of the sensor functions, and enables on-chip signal amplification and conditioning that notably improves the overall sensor performance. The circuitry also includes analog-to-digital converters, and an on-chip interface to transmit the data to off-chip recording units. We expect that our approach will provide a basis for the further development and optimization of gas microsystems.

Influence of glutamine and glycyl-glutamine on in vitro lymphocyte proliferation in children with solid tumors.

It is reported that the proliferative response of lymphocytes is lowered in patients with solid tumors. Glutamine is a major nutrient for rapidly proliferating cells. Unlike glutamine itself, the dipeptide glycyl-glutamine as a source for glutamine is stable in aqueous solutions ex vivo. In order to evaluate the possible therapeutic role of glutamine in lymphocyte proliferation, we investigated its influence on lymphocytes of children with solid tumors before and after chemotherapy. Lymphocytes were collected from 21 children and adolescents suffering from solid tumors (before and after chemotherapy) and from healthy controls. Glutamine and glycyl-glutamine, respectively, were added to cell cultures at concentrations between zero and 1.0 mmol/l. ConA or SAC served as T- or B-cell mitogens, respectively. The lymphocyte proliferation in the healthy control group was similar in degree to lymphocyte proliferation seen in the patients with solid tumors, regardless of the mitogen used. No difference in the degree of lymphocyte proliferation before or after chemotherapy was seen with either source of glutamine. Specific subgroups of malignancies showed trends that differed from the overall findings, but these differences were not found to be statistically significant. Routine supplementation with glutamine in children with solid tumors to enhance lymphocyte function is not supported by the data gained from in vitro proliferation tests.

Glutamine peptide-supplemented long-term total parenteral nutrition: effects on intracellular and extracellular amino acid patterns, nitrogen economy, and tissue morphology in growing rats.

Glutamine (GLN) is a nonessential amino acid that is not included in current regimens for parenteral nutrition because of its chemical instability. This study tested the hypothesis that GLN supplementation during long-term total parenteral nutrition (TPN) (3 weeks) would enhance GLN availability, thereby improving nitrogen economy and growth in a growing rat model: Standard TPN delivering 300 kcal/kg per day (lipid:carbohydrate = 1.1) including 2.1 g of nitrogen per kilogram per day in an all-in-one solution was compared with an isonitrogenous, isocaloric, and isovolemic TPN regimen with 0.29 g of nitrogen per kilogram per day substituted by GLN derived from the dipeptides glycyl-GLN and alanyl-GLN (TPN GLN). Enterally fed controls were included. Analysis was confined to nonbacteremic animals with negative blood culture, in which extracellular and intracellular amino acid concentrations including GLN, nitrogen balance, serum protein concentrations, growth, and histologic sections of liver and small-bowel mucosa (light and scanning electron microscopy) were evaluated. Hepatic intracellular GLN concentrations were significantly lower, in animals receiving GLN-free TPN (11.7 +/- 1.6 nmol/mg fat-free dry and solid tissue mass, n = 9) compared with both GLN-supplemented TPN (16.0 +/- 3.0, n = 7) and enteral feeding (18.2 +/- 1.8, n = 6) (p < .001). Corresponding results were found for intracellular GLN concentrations in skeletal muscle (TPN standard 12.5 +/- 3.1, TPN GLN 14.7 +/- 3.1, enteral control 17.3 +/- 2.3, p < .05), intestinal mucosa, and spleen as well as for plasma concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)

Long-term treatment of latent portosystemic encephalopathy with branched-chain amino acids. A double-blind placebo-controlled crossover study.

This trial was undertaken to assess the safety and efficacy of long-term oral supplementation with branched-chain amino acids as an adjunct to conventional therapy in patients with stable cirrhosis and latent encephalopathy. Latent encephalopathy was diagnosed by psychometric testing, used to assess automobile driving capacity. Seventeen patients with impaired driving capacity received either branched-chain amino acids or placebo for 8 weeks before being crossed over to the other regimen for an equal period. Branched-chain amino acids but not placebo significantly improved psychomotor disturbances (p < 0.01) and driving capacity (p < 0.002). No adverse reactions were observed. We conclude that long-term branched-chain amino acid supplementation is well tolerated and effective in the treatment of impaired automobile driving capacity associated with latent portosystemic encephalopathy.

[Metabolically adapted nutrition following the concept of clinical nutrition therapy--success and prospects]. / Stoffwechseladaptierte Ernährung im Konzept der klinischen Ernährungstherapie--Erfolge und Ausblick.

Modern dietetics abandon the traditional, mainly hypothetically based special types of nutrition. A better knowledge of the physiological and pathological metabolic reactions and the technical possibilities to produce defined, tailor-made dietetics products require a new way of thinking. It is attempted to establish a simple scheme according to the composition and use of balanced and defined diets and to outline future tendencies. In summary, it is concluded that the consequent use of modern nutritional physiology and the application of the actual technologies allow to supply patients with a metabolicly adapted nutrition even under difficult conditions.