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G Lotz

Publications and source records attributed to G Lotz.

8 recordsLinked to original sources
PubMed1995

[Pilot project for evaluation of lung function reference values].

Lung function tests were performed in this study on 139 adults (mean age 36 years), as well as on 91 female persons between 16 and 18 years of age (the latter just starting on their professional careers), the lungs being healthy in each case in both groups. The findings were compared with the currently accepted reference value formulae after Quanjer et al., and Zapletal as well as further developed reference value formulae after Brändli et al., Most of the measurement data obtained by spirometry for the BGFA group of probands are between the two recommended reference values for adults with better coincidence with Brändli's predictions (exceptions being MMEF25-75 MEF 50 and MEF 25). In our studies we obtained higher values than the reference median values after Quanjer and Zapletal for IVC, FVC, FEV1 and PEF by 6-8% and 5-15%, respectively, whereas the values for adults differ from the predictions made by Brändli et al. by -4% to +5%. The flow data MMEF 75-25, MEF 50 and especially MEF 25 are set at too low levels (by 5-23%) by Zapletal's and Brändli's values. Comparatively, the values predicted by Quanjer et al. for the above mentioned flow-volume parameters (with the exception of MEF 75) are too high by 4% to 12%. There are also considerable differences in respect of the reference values for IGV to the tune of +15% in the BGFA group compared to Quanjer et al.; in the BAFAM group the values differ from those of Zapletal et al. by +17%. RV yields results in the BGFA group which are higher by 11% than according to Quanjer's formulae, whereas in the BAFAM group they are higher by 15% compared to Zapletal's predictions. In respect of Rt there are differences to the predictions by Rühle and Matthys by +16% (BGFA group) and +13% (BAFAM group), respectively. The BAFAM group differs from Zapletal's predictions by +11%. Looking at the reference limit values the overall impression is confirmed that the predictions after Quanjer et al. and mostly also those by Zapletal are too low in respect of the abovementioned lung function parameters (in the majority of cases not 5% of the examined probands, as expected, are below those levels, but only about 2%). Females, who had been underrepresented in the previous healthy proband groups, show larger deviations than males in respect of most of the parameters.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1990

[Determination of total lung capacity from the thoracic roentgen image].

Formulas for calculation of total lung capacity from chest X-rays were compiled from literature. Using the total lung capacity measured by bodyplethysmography as reference, these formulas and several modifications were tested for usefulness. The product of lung area in the posterior-anterior X-rays and the largest diameter from sternum to the dorsal rib bow in the frontal X-rays was the most simple and exact roentgenological indicator of total lung capacity. 95%-confidence intervals for predictive values gained by this method revealed to be of similar range as for total lung capacity estimated by the gas dilution methods in comparison to bodyplethysmography.

Adult↗
PubMed1987

Iron uptake by rat duodenal microvillous membrane vesicles: evidence for a carrier mediated transport system.

The mechanism of iron translocation from intestinal lumen to portal plasma is poorly understood. To examine these processes, uptake of Fe2+ and Fe3+ by rat duodenal microvillous membrane vesicles prepared by a Ca2+ precipitation procedure was studied. Membrane aliquots were incubated with increasing concentrations of 59FeCl3 in the presence of a one-thousand-fold molar excess of citrate or 59FeSO4 with a twenty-fold molar excess of L-ascorbic acid. After various time intervals the incubation reaction was stopped by addition of 0.1 mM FeCl3 (4 degrees C), and uptake of 59Fe was determined by a vacuum filtration assay. Initial uptake velocity of 59FeCl3 and 59FeSO4 was determined from the slope of the cumulative uptake curves, which was linear for the first 60 s. Initial uptake rates of both, 59Fe3+ and 59Fe2+ revealed an identical saturable uptake component with a Km of 19-22 nM and Vmax of 8 pmol min-1 mg protein-1. In addition, transport of Fe2+ revealed a linear unspecific uptake phase, which was predominant at high substrate concentrations. Saturable uptake of Fe2+ and Fe3+ was temperature dependent, and significantly reduced by trypsin pretreatment of the microvillous membrane vesicles, indicating the involvement of a protein in the uptake process. This suggestion was pursued by isolation of an iron binding protein from duodenal brushborder membranes. After solubilization of microvillous plasma membranes with 1% Triton X 100, affinity chromatography of the membrane protein mixture over an iron chelate gel derived from epoxy activated Sepharose and elution with 50 mM EDTA yielded a single 52,000 dalton protein. The protein co-chromatographed over an Ultro-Pac TSK G 3000SW HPLC column together with 59FeCl3 and 59FeSO4. It showed no immunologic activity to rabbit antibodies against whole rat serum or rat transferrin. Furthermore, by photoaffinity labelling technique a single iron binding protein with a molecular weight of about 52,000 dalton was identified in microvillous membranes of the rat duodenum. These data are compatible with the hypothesis that intestinal iron absorption is mediated by a specific carrier-dependent transport system.

Animals↗
PubMed1985

Identification, isolation, and partial characterization of a fatty acid binding protein from rat jejunal microvillous membranes.

The mechanisms by which FFA are absorbed by the gut are unclear. To examine these processes, binding of [14C]oleate to isolated rat jejunal microvillous membranes (MVM) was studied in vitro. When [14C]oleate alone or compounded with bovine serum albumin at various molar ratios was incubated with MVM aliquots, binding was time- and temperature-dependent, inhibitable by addition of excess cold oleate, and decreased by heat denaturation or trypsin digestion of the membranes. When [14C]oleate binding to heat denatured MVM, which increased continuously as a function of the free oleate concentration and was taken as a measure of nonspecific binding, was subtracted from total binding to native MVM, a curve suggestive of saturable specific binding was observed. In contrast to fatty acids, there was no specific binding of [14C]taurocholate or [35S]sulfobromophthalein to jejunal MVM. After MVM solubilization with 1% Triton X-100, affinity chromatography over oleate-agarose and elution with 7 M urea yielded a single 40,000-mol-wt protein. This Sudan Black/periodic acid-Schiff-stain-negative protein co-chromatographed on Sephadex G-100 with [14C]oleate, [14C]palmitate, [14C]arachidonate, and [14C]linoleate, but not with the [14C]oleate ester of cholesterol, [14C]phosphatidylcholine, [14C]taurocholate, or [35S]sulfobromophthalein. A rabbit antibody to the previously reported hepatic membrane fatty acid binding protein (FABP) gave a single line of immunologic identity between the FABPs of rat jejunum and rat liver membrane. It inhibited the binding of [14C]oleate to native MVM but not heat denatured MVM, and, in immunohistochemical studies, demonstrated the presence of the FABP in the apical and lateral portions of the brush border cells of the jejunum, but not on the luminal surface of esophagus or colon. These data are compatible with the hypothesis that a specific FABP plays a role in fatty acid absorption from the gut.

Animals↗