[Creation of a control group by matched pairs with GKV routine data for the evaluation of enrollment models]. / Bildung einer Kontrollgruppe mithilfe von Matched-Pairs auf Basis von GKV-Routinedaten zur prospektiven Evaluation von Einschreibemodellen.

BACKGROUND: Various study approaches can be considered for the investigation of the efficiency of enrollment models, like GP-centred health-care contract or disease management programmes. As an active and independent enrollment into care models is effected by the insured (self-selection), a randomisation cannot be applied. The matched pairs design - in which for every insured a control insured with comparable morbidity is selected - presents an alternative investigation method. A precondition is a model that describes appropriately the morbidity on the basis of available routine data. TARGET: The aim of this study was to develop a procedure that selects comparable insured persons on the basis of routine data of the statutory health-care funds. METHODS: Apart from age, gender, care status, insured status, days of disability, region, health insurance and belonging to an enrollment model, also ambulant as well as stationary performance data for the year 2005 following the PCG/DCG procedure for morbidity-oriented matching design developed by Lamers and Vliet (2003) were applied. Thereby the consumption of certain medications prescribed is determining for the allocation of patients to pharmaceutical cost groups (PCG). Additionally a classification into diagnosis cost groups (DCG) according to stationary diagnoses was conducted. RESULTS: Within the scope of the enrollment models the formation of matched pairs following the PCG/DCG procedure represents an appropriate study design for the creation of a control group. In the first year of enrollment the insured of the interventional and those of the control group show a comparable morbidity. When applying 9 matching criteria a control insured person can be found for 87% of the enrolled individuals. DISCUSSION/CONCLUSIONS: There are various and complex possibilities to define morbidity. Variable parameters within the presented matched pairs design are the number of used matching criteria as well as minimum drug consumption limit relevant for the classification in PCGs. Alternative models are possible for morbidity definition considering, apart from the stationary diagnosis, also the ambulant diagnosis. When taking into account a higher number of morbidity criteria, the matched pairs design is confronted with dimensionality issues. The propensity score matching is discussed as approach to solve this problem.

Decrease of Nitrate Reductase Activity in Spinach Leaves during a Light-Dark Transition.

In leaves of spinach plants (Spinacia oleracea L.) performing CO(2) and NO(3) (-) assimilation, at the time of sudden darkening, which eliminates photosystem I-dependent nitrite reduction, only a minor temporary increase of the leaf nitrite content is observed. Because nitrate reduction does not depend on redox equivalents generated by photosystem I activity, a continuation of nitrate reduction after darkening would result in a large accumulation of nitrite in the leaves within a very short time, which is not observed. Measurements of the extractable nitrate reductase activity from spinach leaves assayed under standard conditions showed that in these leaves the nitrate reductase activity decreased during darkening to 15% of the control value with a half-time of only 2 minutes. Apparently, in these leaves nitrate reductase is very rapidly inactivated at sudden darkness avoiding an accumulation of the toxic nitrite in the cells.

Amino Acid and sucrose content determined in the cytosolic, chloroplastic, and vacuolar compartments and in the Phloem sap of spinach leaves.

Amino acid and sucrose contents were analyzed in the chloroplastic, cytosolic, and vacuolar compartments and in the phloem sap of illuminated spinach leaves (Spinacia oleracea L.). The determination of subcellular metabolite distribution was carried out by nonaqueous fractionation of frozen and lyophilized leaf material using a novel three-compartment calculation method. The phloem sap was collected by aphid stylets which had been severed by a laser beam. Subcellular analysis revealed that the amino acids found in leaves are located mainly in the chloroplast stroma and in the cytosol, the sum of their concentrations amounting to 151 and 121 millimolar, respectively, whereas the amino acid concentrations in the vacuole are one order of magnitude lower. The amino acid concentrations in the phloem sap are found to be not very different from the cytosolic concentrations, whereas the sieve tube concentration of sucrose is found to be one order of magnitude higher than in the cytosol. It is concluded that the phloem loading results in a preferential extraction of sucrose from the source cells.

Redox Transfer across the Inner Chloroplast Envelope Membrane.

In leaves of spinach plants (Spinacia oleracea L.) grown in ambient CO(2) the subcellular contents of adenylates, pyridine nucleotides, 3-phosphoglycerate, dihydroxyacetone phosphate, malate, glutamate, 2-oxoglutarate, and aspartate were assayed in the light and in the dark by nonaqueous fractionation technique. From the concentrations of NADP and NADPH determined in the chloroplast fraction of illuminated leaves the stromal NADPH to NADP ratio is calculated to be 0.5. For the cytosol a NADH to NAD ratio of 10(-3) is calculated from the assay of the concentrations of NAD, malate, glutamate, aspartate, and 2-oxoglutarate on the assumption that the reactions catalyzed by the cytosolic glutamate oxaloacetate transaminase and malate dehydrogenase are not far away from equilibrium. For the transfer of redox equivalents from the chloroplastic NADPH to the cytosolic NAD two metabolite shuttles are operating across the inner envelope membrane: the triosephosphate-3-phosphoglycerate shuttle and the malate-oxaloacetate shuttle. Although both shuttles would have the capacity to level the redox state of the stromal and cytosolic compartment, this apparently does not occur. To gain an insight into the regulatory processes we calculated the free energy of the enzymic reactions and of the translocation steps involved. From the results it is concluded that the triosephosphate-3-phosphoglycerate shuttle is mainly controlled by the chloroplastic reaction of 3-phosphoglycerate reduction and of the cytosolic reaction of triosephosphate oxidation. The malate-oxaloacetate shuttle is found to be regulated by the chloroplastic NADP-malate dehydrogenase and also by the translocating step across the envelope membrane.