Biomedical subjects

R Winkler

Publications and source records attributed to R Winkler.

At least 37 records · Page 2Linked to original sources

PubMed2001

Radon concentration in soil gas: a comparison of methods.

Various methods to determine 222Rn concentration in soil gas were tested at two sites with different soil types in a depth of about 1 m. They included instantaneous (spot), continuous (real-time) and time-averaging procedures. The first test site had a porous soil with high gravel content. At this site, radon concentrations obtained with the different methods agreed within the error limits of the procedures. The other site exhibited a largely impermeable clay soil and at this site, the measured radon concentrations differed up to a factor of two depending on the method. The applicability of the various procedures in the field is discussed.

Dose-Response Relationship, Radiation↗

PubMed2001

Nuclide-dependent local and collector surface effects in sampling of radioactive deposition to ground.

After the end of atmospheric nuclear weapons tests and after the Chernobyl accident, the deposition characteristics of 137Cs changed from a predominant wet deposition to the present resuspension mechanism characterised by predominant dry deposition. To study the consequences of this change for deposition sampling, monthly deposition data from two collectors located at a distance of 600 m were compared from 1991 to 2000. On the average, the deposition rates differed by roughly a factor of two for 137Cs, whereas for the cosmogenic 7Be a difference was not detectable with statistical significance. Further, a "funnel" collector with a mostly dry surface collected on the long-term average 36% less of 137Cs, but 8% less of 7Be, than a "pot" collector with a continuously water-covered surface. Since for 137Cs deposition and the bulk deposition a similar behaviour was found, a stronger sensitivity of other resuspension-derived radionuclides against local and collector surface variations can generally be expected.

Journal Article↗

PubMed2001

Three cases of C-ANCA-positive vasculitis treated with immunoadsorption: possible benefit in early treatment.

Wegener's granulomatosis is a vasculitic disease predominantly affecting the upper respiratory tract, lungs, and kidneys. Three patients with Wegener's granulomatosis and rapidly progressive glomerulonephritis were treated with an intensified regimen of immunoadsorption (IA) (Excorim or Therasorb) in addition to cyclophosphamide (CYC) and methylprednisolone (PRE). Patient A had been in remission under oral CYC/PRE. The first exacerbation was treated successfully with 4 IA treatments without changing medication. Patient B experienced 3 flares within 1 year, which were treated with 28 IA (3-7 IAs/course), intravenous CYC after each course, and PRE. A fall of creatinine levels from 120 to 190 micromol/L to 100 micromol/L was noted after IA and before administration of CYC. Patient C presented in uremia. Autoantibodies were eliminated by 11 IA treatments parallel to CYC/PRE therapy. They remained within a normal range for >1 year's follow-up; however, kidney function did not return. In conclusion, the observations in Patients A and B suggest a beneficial therapeutic effect of early IA in WG.

Adult↗

PubMed2001

[Anorectal ulcers--etiology, diagnosis, therapy (simple rectal ulcer, radiogenic ulcer, CED].

Ulcers of the anorectal region are very variable in etiology and morphology. Often differential diagnosis is even possible by (excisional-)biopsy. As they are symptoms of any kind of disease, therapy has to be derived from this disease. Therefore surgery often only plays an additional part besides clearing the diagnosis, although the surgeon is mostly the first consultant, so being responsible for ongoing therapy. Some special diseases, their problems and therapeutical options, are described in detail.

Anal Canal↗

PubMed2000

Seasonal and long-term variation of 210Pb concentration in air, atmospheric deposition rate and total deposition velocity in south Germany.

The activity concentration in air and atmospheric deposition rate of the long-lived radon progeny 210Pb has been investigated at Munich-Neuherberg, south Germany, from 1972 (activity concentration) and from 1981 (atmospheric flux) to 1999. For these periods, the continuous measurements yielded an average 210Pb activity concentration at ground level of 0.57 mBq m(-3) and an average total 210Pb deposition rate to ground of 180 Bq m(-2) year(-1). The average total deposition velocity, which relates the total 210Pb deposition rate to the 210Pb activity concentration was calculated to be 1.0 cm s(-1). The variation of the data with time was studied by time-series analysis and distinct seasonal patterns were identified. Maximum 210Pb activity concentrations in air are observed in the autumn and winter months (October through February) of each year. By contrast, the maximum 210Pb deposition rate is observed during summer (June-August), i.e. in the months with the highest amount of rainfall at this site. Like the 210Pb deposition rate, the total deposition velocity exhibits a seasonal pattern with maximum values in summer. Due to the long observation period of 18 years, it was possible to observe for the first time a strong positive relationship between 210Pb deposition and precipitation, especially for the months May and June and to a smaller extent for several other months. In the long-term, variations of approximately a factor of 2 were observed in the annual average 210Pb activity concentrations, the annual deposition sums and the annual average deposition velocities. Since around 1981 210Pb concentrations in air steadily decreased while 210Pb depositions increased. As a consequence of these significant trends, the time series of the total deposition velocity exhibits a trend of the data from approximately 0.7 cm s(-1) in 1981 to 1.7 cm s(-1) in 1999.

Air Pollution↗

PubMed2000

Highly anisotropic g-factor of two-dimensional hole systems

Coupling the spin degree of freedom to the anisotropic orbital motion of two-dimensional (2D) hole systems gives rise to a highly anisotropic Zeeman splitting with respect to different orientations of an in-plane magnetic field B relative to the crystal axes. This mechanism has no analog in the bulk band structure. We obtain good, qualitative agreement between theory and experimental data, taken in GaAs 2D hole systems grown on (113) substrates, showing the anisotropic depopulation of the upper spin subband as a function of in-plane B.

Journal Article↗

PubMed2000

Anisotropic magnetoresistance of two-dimensional holes in GaAs

Experiments on high-quality GaAs (311)A two-dimensional holes at low temperatures reveal a remarkable dependence of the magnetoresistance, measured with an in-plane magnetic field ( B), on the direction of B relative to both the crystal axes and the current direction. The magnetoresistance features, and in particular the value of B above which the resistivity exhibits an insulating behavior, depend on the orientation of B. To explain the data, the anisotropic band structure of the holes and a repopulation of the spin subbands in the presence of B, as well as the coupling of the orbital motion to B, need to be taken into account.

Journal Article↗

PubMed2000

Endogenously produced glycosaminoglycans affecting the release of lipoprotein lipase from macrophages and the interaction with lipoproteins.

Macrophages are intimately involved in the pathogenesis of atherosclerotic diseases. A key feature of this process is their uptake of various lipoproteins and subsequent transformation to foam cells. Since lipoprotein lipase (LPL) is believed to play a role in foam cell formation, we investigated if endogenously produced proteoglycans (PGs) affect the release of this enzyme from macrophages. The human leukaemic cell line THP-1 which differentiates into macrophages by treatment with phorbol ester (phorbol 12-myristate 13-acetate) served as a model. The differentiation of THP-1 macrophages promoted the release of PGs into the cell medium which caused the detachment of LPL activity from the cell surface, and prevented LPL re-uptake and inactivation. These PGs were mainly composed of chondroitin sulfate type and exerted a heparin-like effect on LPL release. LPL is known to increase the cell association of lipoproteins by the well known bridging function. Exogenous bovine LPL at a concentration of 1 microg/ml enhanced low density lipoprotein (LDL)-binding 10-fold. Endogenously produced PGs reduced LPL-mediated binding of LDL. It is proposed that the differentiation-dependent increase in the release of PGs interferes with binding of LPL and reduces lipoprotein-binding to macrophages.

Arteriosclerosis↗

PubMed2000

Anomalous magneto-oscillations in two-dimensional systems

The frequencies of Shubnikov-de Haas oscillations have long been used to measure the unequal population of spin-split two-dimensional subbands in inversion asymmetric systems. We report self-consistent numerical calculations and experimental results which indicate that these oscillations are not simply related to the zero-magnetic-field spin-subband densities.

Journal Article↗

PubMed2000

Effect of iodide on total antioxidant status of human serum.

Free radicals and subsequent lipid peroxidation have been implicated in the pathogenesis of several degenerative and chronic diseases which are also treated frequently in spas. There are some data arising from previous studies which support an antioxidant or scavenging effect of iodide, being the essential ingredient of a therapeutically used local brine. The aim of the study was to test the antioxidant capacity of iodide in human serum. For this reason we measured the so-called Total Antioxidant Status determined by a colorimetric method, which reflects the protection against the attack of reactive oxygen species, including enzymic and non-enzymic antioxidants. Exogenous iodide applied as NaI, shows a significantly increased antioxidant capacity in comparison with NaCl at a concentration of 15 microM, which is quite comparable to the upper range of serum iodide levels achieved through balneo-therapeutical intervention. This result is in accordance with previous results from in vitro depolymerization experiments with hyaluronic acid. The antioxidant effect of 15 microM NaI has been found to be approaching the physiologically relevant concentration of ascorbic acid (50 microM).

Adult↗

PubMed2000

Removal of immunoglobulins by a protein A versus an antihuman immunoglobulin G-based system: evaluation of 602 sessions of extracorporeal immunoadsorption.

Elimination of IgG can be achieved by extracorporeal immunoadsorption (IA) based on specific binding to either staphylococcal protein A (Excorim) or sheep polyclonal antibodies directed against human IgG (Therasorb). In 602 analyzed sessions of IA, elimination of IgG was 60% through 80% depending on the treated plasma volume, with no significant difference between the mentioned systems. However, the decrease of IgM and IgA was approximately 50% in the anti-IgG compared to 20-40% in the protein A system. Plasma albumin concentration decreased by 20% in the anti-IgG system compared to 15% in the protein A system, and hemoglobin values increased by 2% in the anti-IgG system and decreased by 6% in the protein A system. In conclusion, a clinical relevance for these findings cannot be ruled out, and the individual choice might depend on the clinical situation and laboratory findings.

Antibodies, Anti-Idiotypic↗

PubMed2000

Involvement of insulin-like growth factors in early T cell development: a study using fetal thymic organ cultures.

The expression of insulin-like growth factor (IGF) and IGF receptor genes was investigated by RT-PCR during ontogeny of the murine thymus. IGF-1, IGF-1R, M6P/IGF-2R genes are expressed in the thymus both in fetal and postnatal life, whereas IGF-2 messenger RNAs (mRNAs) decline after birth but are still detectable on the seventh week. By in situ hybridization, IGF-2 transcripts were located in the outer cortex and medulla of the postnatal thymus, and on the whole surface ofthe epithelial-like network in the fetal thymus. The effects of anti-IGFs and IGF-receptors neutralizing Abs on the generation of pre-T cell subpopulations were then investigated using fetal thymic organ cultures (FTOC). FTOC treatment with an anti-IGF-2 mAb, an anti-IGF-1R mAb, or an anti-M6P/IGF-2R polyclonal Ab induced a blockade of T cell differentiation at the CD4-CD8- stage, as shown by a significant increase in the percentage of CD4-CD8- cells and a decrease in the percentage of CD4+CD8+ cells. Moreover, anti-IGF-2 Ab treatment induced an increase in CD8+ cells suggesting that thymic IGF-2 might have a role in determining differentiation into the CD4 or CD8 lineage. Anti-IGF-1 Ab treatment decreased the proportion in CD4-CD8- cells and increased the frequency in CD4+CD8+. FTOC treatment with anti-(pro)insulin did not exert any significant effect on T cell development. These data indicate that the intrathymic IGF-mediated signaling plays an active role in the early steps of T cell differentiation during fetal development.

Animals↗

PubMed2000

[The IGF system: summary and recent data].

We are entitled to state that our knowledge about the IGF system has literally exploded in the last years. Having been considered for some time merely as trophic and mitogenic factors, the IGFs now appear as molecules essential for the differentiation of many cell types, and even more so, as powerful protective agents for the nervous and the cardiovascular systems. However, these properties so beneficial in normal physiological conditions, are subverted by the cancerous cells who use them to extend their life span and resist therapy. The IGFs did not live up to expectations in the treatment of diabetes; however, today their capacity to improve the condition of patients suffering from severe neurological, renal or muscle diseases is tested. The IGF system might also be targetted by the anticancer treatments. In the following paper we have briefly summarized our knowledge on the IGF system, and presented in more detail the recent data.

Apoptosis↗

PubMed1999

Cloning of breakpoints in and downstream the IGF2 gene that are associated with overexpression of IGF2 transcripts in colorectal tumours.

The human IGF2 gene belongs to a group of imprinted genes clustered on the short arm of chromosome 11, band p15.5. It contains 9 exons and spans over 30 kb. IGF2 mRNA overexpression has been reported in human tumours and in some inherited growth disorders. It was recently demonstrated that IGF2 mRNA overexpression contributes to tumour progression and that loss of parental imprinting as well as altered transcription factors are contributing to this overexpression. We have reported structural alterations in the 3' region of the IGF2 gene in two colorectal tumours that overexpressed the IGF2 transcript by 200- and 800-fold. We cloned by the vectorette-PCR strategy, genomic DNA fragments containing the breakpoints from these tumours. The sequencing of these fragments positioned the breakpoint 2 kb downstream the IGF2 gene in one tumour, and in exon 9 in the second. Both breakpoints occurred in regions containing repetitive elements: a TGGA repeat we have identified downstream the gene, and the (CA)n repetition in exon 9. We hypothesize that a negative regulatory element, located downstream the IGF2 gene, has been deleted following these structural alterations and leads to IGF2 gene overexpression.

Chromosome Aberrations↗

PubMed1999

Radar and optical observations of asteroid 1998 KY26

Observations of near-Earth asteroid 1998 KY26 shortly after its discovery reveal a slightly elongated spheroid with a diameter of about 30 meters, a composition analogous to carbonaceous chondritic meteorites, and a rotation period of 10.7 minutes, which is an order of magnitude shorter than that measured for any other solar system object. The rotation is too rapid for 1998 KY26 to consist of multiple components bound together just by their mutual gravitational attraction. This monolithic object probably is a fragment derived from cratering or collisional destruction of a much larger asteroid.

Journal Article↗

PubMed1999

The effect of spin splitting on the metallic behavior of a two-dimensional system

Experiments on a constant-density two-dimensional hole system in a gallium arsenide quantum well revealed that the metallic behavior observed in the zero-magnetic-field temperature dependence of the resistivity depends on the symmetry of the confinement potential and the resulting spin splitting of the valence band.

Journal Article↗

PubMed1999

[1998 prognosis of left ventricular dysfunction in a maximum care non-university hospital. Analysis of the Ludwigshafen LVD Registry].

BACKGROUND: Prognostic data on heart failure rely on epidemiological studies or large clinical trials. These data are not to transfer easily on everyday practice. OBJECTIVE: To assess the prognosis of left ventricular dysfunction under the therapeutic conditions of the 1990s. SETTING: Nonuniversity tertiary care hospital. PATIENTS AND METHODS: Since January 1995 consecutive and complete registry of all inpatients presenting with a left ventricular dysfunction (EF < 45%). No exclusion criteria. RESULTS: n = 512, mean age 64 years, 77% male, mean NYHA class 2.5, left ventricular EF 31%. ETIOLOGY: 58% coronary heart disease, 28% dilated cardiomyopathy. Medical treatment consisting of 91% ACE inhibitors, ACE inhibitor dosage 52% of the recommended dose, 42% beta-blockers, 70% diuretics, and 63% digitalis. Follow-up completeness 95.5%. One-year mortality 64/489 patients (13.9%). Determinants of mortality: NYHA III/IV, EF < 30%, malignant disease, age > 75 years. CONCLUSION: In spite of the aforementioned medical treatment and a proportion of 14.8% implanted defibrillators in 1998, the one-year mortality of ventricular dysfunction is as high as 13.9%. In everyday practice the prognostic effect of ACE inhibition and beta-blockade is not completely utilized.

Adrenergic beta-Antagonists↗

PubMed1999

Characterization of the insulin-like growth factor axis in the human thymus.

The components of the insulin-like growth factor (IGF) axis have been investigated in the normal human thymus. Using ribonuclease protection assays (RPA), IGF-II transcripts were detected in the normal human thymus. By reverse transcriptase polymerase chain reaction (RT-PCR) analyses, promoters P3 and P4 were found to be active in the transcription of IGF2 gene within human thymic epithelial cells (TEC). No IGF-II mRNA could be detected in human lymphoid Jurkat T cells with 30 cycles of RT-PCR. By Northern blot analyses, IGFBP-2 to -6 (but not IGFBP-1) were found to be expressed in TEC with a predominance of IGFBP-4. Interestingly, Jurkat T cells only express IGFBP-2 but at high levels. The type 1 IGF receptor was detected in Jurkat T cells but not in human TEC. The identification of the components of the IGF axis within separate compartments of the human thymus adds further evidence for a role of this axis in the control of T-cell development. The precise influence of thymic IGF axis upon T-cell differentiation and immunological self-tolerance however needs to be further investigated.

Blotting, Southern↗