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Biomedical subjects

B Meller

Publications and source records attributed to B Meller.

7 recordsLinked to original sources
PubMed2001

Chronic inborn erythrocytosis leads to cardiac dysfunction and premature death in mice overexpressing erythropoietin.

The most common cause of an increase of the hematocrit is secondary to elevated erythropoietin levels. Erythrocytosis is assumed to cause higher blood viscosity that could put the cardiovascular system at hemodynamic and rheological risks. Secondary erythrocytosis results from tissue hypoxia, and one can hardly define what cardiovascular consequences are caused by chronic erythrocytosis or hypoxia. Herein, a novel transgenic (tg) mouse line is characterized that is erythrocytotic because of chronic overexpression of the human erythropoietin gene. These mice grow up well, reaching a hematocrit of about 0.80 in adulthood. Blood volume of adult tg mice was markedly increased by 75%. Unexpectedly, blood pressure was not elevated and cardiac output was not decreased. Still, the adult tg mice showed features of cardiac dysfunction with increased heart weight. In vivo, high-frequency echocardiography revealed marked ventricular dilatation that was confirmed by histologic examination. Furthermore, by transmission electron microscopy, a prominent intracellular edema of the cardiomyocytes was seen. Exercise performance of the tg mice was dramatically reduced, unmasking the severity of their compromised cardiovascular function. In addition, life expectancy of the tg mice was significantly reduced to 7.4 months. Our findings suggest that severe erythrocytosis per se results in cardiac dysfunction and markedly reduced life span.

Age Factors↗
PubMed2001

Comparing Early to Middle Miocene floras and probable vegetation types of Oberdorf N Voitsberg (Austria), Bohemia (Czech Republic), and Wackersdorf (Germany).

The Early Miocene vegetation of western Styria, Austria, is reconstructed on the basis of detailed investigations of leaves and diaspores from the mining area Oberdorf N Voitsberg. In this paper, the flora and probable vegetation are compared with other assemblages of similar age from the Czech Republic and Germany to elucidate the diversity of wetland and mesophytic plant communities. The floristic composition and the vegetational units represented in Oberdorf are compared to the middle part of the Most Formation (M Most Fm), Cypris Shale, Mydlovary Formation (Mydlovary Fm) of Bohemia, and the Wackersdorf mining area of Bavaria. Among these sites, Oberdorf is extremely poor in hydrophytes and reed-like monocotyledons, indicating rare pond-like habitats as well as possibly more closed swamp forest conditions than, e.g. in the M Most Fm. In Oberdorf, relatively high pH-values in the lignite-forming swamps and the possible scarcity of acidic, nutrient-poor (sandy) soils have probably influenced the floristic composition of the azonal communities. The peat-forming associations in all regions share the abundance of Glyptostrobus europaeus. However, distinct differences in the accompanying elements, such as Taxodium dubium (present and abundant only in the M Most Fm) indicate even stronger floristic variability of Early(/Middle) Miocene peat-forming and riparian plant communities than previously expected. The virtual absence of Pinus, Engelhardia, Comptonia, and probably also of Quercus kubinyii/Quercus drymeja in the megafossil record of Oberdorf can possibly be explained by the edaphic conditions. The abundance of Sequoia abietina (absent in all the other compared sites), which we assign to riparian (and mesophytic) forests in Oberdorf, may have been favoured by rich alluvial soils.In the mesophytic associations, thermophilous elements of the Lauraceae, Mastixiaceae, Symplocaceae, and Rutaceae are diverse. Usually they include Trigonobalanopsis rhamnoides/Trigonobalanopsis exacantha, an evergreen Fagaceae. This assemblage type corresponds with the Younger Mastixioid Flora sensu Mai. The Younger Mastixioid Flora is best developed in Wackersdorf, less distinct in Oberdorf, and likely in the Cypris Shale and Mydlovary Fm. It is not traceable in the M Most Fm.

Journal Article↗
PubMed2000

Radioiodine therapy in Graves' hyperthyroidism: determination of individual optimum target dose.

UNLABELLED: The aim of this study was to investigate the results of different volume-dependent target doses on clinical outcome 6 months after radioiodine therapy (RITh) and its correlation with post therapeutic thyroid volumes (Vpost) in patients with Graves' disease. This analysis was designed to determine factors improving the results of radioiodine therapy without increasing target doses generally, as has been recommended recently. We studied consecutive data from 102 patients with Graves' disease, who had initial radioiodine therapy between 1991 and 1995. The 131I activities were calculated according to the formula of Marinelli. In addition to the normal calculation individual target doses were adjusted to the thyroid volumes of each patient before therapy. For statistical evaluation, the patients were divided into three subgroups of comparable sample sizes: Group I included those with a thyroid volume <15 ml before therapy. Group II included those ranging from a 15-25 ml volume before therapy and group III included those with thyroid volumes >25 ml. Laboratory thyroid parameters and thyroid volumes were measured in those groups before and 6 months after therapy. RESULTS: Analysis of all patients revealed a significantly higher rate of hypothyroidism (54%) and fewer cases of hyperthyroidism (15%) six months after therapy in cases with Vpost smaller than 8 ml. The median Vpost needed to achieve an optimum therapeutic success rate (rate of eu- or hypothyroidism) was smaller than 5 ml in group I and smaller than 10 ml in group II. Therapeutic success was associated with different target doses in each group, 150,220 and 260 Gy for groups I, II, and III respectively. CONCLUSIONS: Post therapeutic thyroid volumes correlated significantly with clinical outcome six months after therapy. An adjustment of the target doses based on thyroid volumes before therapy will lead to an appropriate reduction of thyroid volumes. Thus, in the individual case clinical outcome could be improved without applying higher target doses in all patients. This would ensure a better utilization of limited resources in medical care e.g. through a shorter hospital stay.

Adult↗
PubMed1998

Influence of radioiodine therapy on urinary iodine excretion.

AIM: In 214 patients with benign thyroid diseases the time-course of urinary iodine excretion (UIE) was investigated in order to identify changes after radioiodine therapy (RITh). METHOD: UIE was measured photometrically (cerium-arsenite method) and related to urinary creatinine on the first and last day of the radioiodine test and then three days, seven days, four weeks, and six months after 131I administration. RESULTS: As compared with the level found immediately before radioiodine therapy, median UIE had almost doubled four weeks after therapy and was still significantly elevated six months after therapy. This increase correlated significantly with the target volume as measured by scintigraphy and sonography. CONCLUSIONS: The persistent elevation of UIE for months after RITh is a measure of treatment-induced damage to thyrocytes. Therefore, in view of the unfavourable kinetics of iodine that follow it, RITh should if possible be given via a single-dose regime.

Antithyroid Agents↗
PubMed1986

Patellar surface strain.

We measured longitudinal surface strains on the anterior patella at controlled simulated quadriceps loads, quadriceps angles, and knee flexion angles. We studied both the natural patella and patellas resurfaced with domed, bifaceted, and metal backed polyethylene components. Twelve matched pairs of fresh human cadaver knee specimens were tested. Midanterior longitudinal patellar strains were greatest at knee flexion angles at 45 to 60 degrees of knee flexion. Alterations in quadriceps angle medially and laterally did not decrease recorded strain values significantly. Polyethylene patellar prostheses increased patellar strains but a bifaceted component or "total contact" design minimized this effect. Metal support for the prosthetic patella decreased the recorded surface strains. This study of patellar surface strain at the three midline locations provides experimental results that may prove useful for design and validation of analytic models of the patella. The study also suggests that patellar surface strain measures may provide a method for evaluating the effects of patellar prosthesis design and resurfacing procedures.

Aged↗