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Biomedical subjects

B Gebauer

Publications and source records attributed to B Gebauer.

At least 37 records · Page 2Linked to original sources
PubMed2001

[Multi-slice spiral CT: 3D CT angiography for evaluating therapeutically relevant stenosis in peripheral arterial occlusive disease].

PURPOSE: Evaluation of 3D multislice CT angiography for the assessment of relevant stenoses of pelvic arteries and arteries of the lower extremity in patients with peripheral artery occlusive disease compared to digital subtraction angiography. METHOD/MATERIALS: For this study we examined 31 patients with peripheral artery occlusive disease. All patients received a multislice helical CT angiography and arterial digital subtraction angiography. Multislice CT angiography was performed with a Somatom Plus 4 Volume Zoom (Siemens, Erlangen, Germany). After test bolus injection of 20 ml Ultravist 370 (Schering AG, Berlin) additional 150 ml were applied with a flow rate of 3 ml/sec and a scan delay between 20-35 sec depending on individual blood circulation time. Collimation was 4 x 2.5 mm with a pitch of 6. Reconstructed slice thickness was 3 mm. 3D reconstructions of arteries of pelvic and lower extremity arteries were performed in volume rendering technique on a 3D Virtuoso workstation (Siemens, Erlangen). RESULTS: For the assessment of therapeutically relevant stenoses (over 50% reduction of luminal diameter) multislice CT achieved the following results compared to conventional angiography for the diagnosis of stenosis: sensitivity of 86%, specificity of 86% and an accuracy of 72%. CONCLUSIONS: Multislice helical CT angiography of pelvic arteries and arteries of the thigh represents a reliable means for the detection of relevant stenoses in patients with peripheral occlusive artery disease.

Adult↗
PubMed1999

Removal of detergent and solvent from solvent-detergent-treated immunoglobulins.

The solvent-detergent (S/D) method was applied for inactivation of lipid-enveloped viruses during the production of immunoglobulins. Amberlite XAD-7 resin was used for removal of solvent (tri-n-butyl phosphate, TnBP) and detergent (Triton X-100) after the performed S/D inactivation procedure. The S/D reagents from the immunoglobulin preparation were adsorbed on Amberlite XAD-7, while immunoglobulins passed through the column and retained their biological activity. Using the method developed here, the final immunoglobulin preparation contains less than 1 ppm of Triton X-100 and less than 2 ppm TnBP.

Acrylic Resins↗
PubMed1999

Ion-exchange chromatography separation of the detergent and the solvent from immunoglobulins after solvent-detergent treatment.

For inactivation of lipid-enveloped viruses during the immunoglobulin production, the solvent-detergent (S/D) method was applied. Tri-n-butyl phosphate (solvent) and Triton X-100 (detergent) were removed from S/D treated immunoglobulins by ion-exchange chromatography on Q-Sepharose Fast Flow (FF). During the chromatographic procedure immunoglobulins remained bound on a Q-Sepharose FF, whereas solvent and detergent were eluted by washing with starting buffer. Elution of immunoglobulins was achieved by increasing the ionic strength of the starting buffer. The final immunoglobulin preparation contained less than 10 microg/ml of Triton X-100 and less than 2 microg/ml tri-n-butyl phosphate. It was confirmed that the S/D procedure did not cause a significant change in polymers and specific antibodies content. Immunoglobulin classes were also not affected by the same procedure.

Chromatography, Ion Exchange↗
PubMed1998

Characterization of F VIII concentrates produced by two methods incorporating double virus inactivation.

The trend toward the production of high purity factor VIII concentrates for clinical use is still in progress. Although all plasma derivatives must undergo viral inactivation procedures, the possibility of transmission of viral diseases is not completely eliminated. In order to reduce such risk, we have included double virus inactivation in the procedure of factor VIII concentrate production. In a scale-up procedure for isolation of factor VIII cryoprecipitate, two methods were used. The first is based on the chromatographic purification of factor VIII after pasteurization of cryoprecipitate solution and solvent/detergent (S/D) inactivation of viruses. The second is based on multistep precipitation of factor VIII by sodium chloride and glycine. Viral inactivation was performed by combination of S/D treatment and heating of final freeze-dried product 30 min at 100 degrees C. The typical yield of factor VIII activity in the freeze-dried product was about 20% for the first method, and 25-30% for the second. Electrophoretic analyses of both factor VIII preparations by SDS-PAGE and IEF show very low content of contaminant proteins, in accordance with observed 400-650-fold increase of their specific activity over plasma. Both factor VIII products were stable in the liquid state for more than 24 h at room temperature. The final products, after double viral inactivation, are considered to be suitable for clinical evaluations.

Antiviral Agents↗
PubMed1998

Changes at the extracellular matrix during acute and chronic rejection in human liver transplantation.

We have previously observed changes at the extracellular matrix (ECM) which significantly correlated with the extent of preservation and reperfusion injury. In the present study, we attempted to investigate whether the ECM may be also involved in the pathophysiological sequelae of acute and chronic rejection. Of 81 patients monitored for the ECM parameters laminin, hyaluronic acid, fibronectin receptor, and transforming growth factor (TGF)-beta, 28 patients developed acute rejection (< 1 month), in 14 patients (17.4%) acute rejection was steroid resistant, 4 patients (4.5%) developed early chronic rejection following acute steroid-resistant rejection. Acute and chronic rejection were confirmed by established clinical and histological criteria. Laminin levels were significantly increased in patients experiencing acute steroid-resistant rejection (4204 +/- 133 ng/ml; P < or = 0.01) compared with patients with steroid-sensitive rejection (1059 +/- 27.3 ng/ ml) and with an uneventful postoperative course (1214 +/- 17.4 ng/ml). No increase in laminin was observed in those four patients who developed early chronic rejection (1099 +/- 58.7 ng/ml). Hyaluronic acid, fibronectin receptor, and TGF-beta levels also increased in patients with acute steroid-resistant rejection; hyaluronic acid: 290 +/- 10.8 micrograms/l vs 154 +/- 13.6 micrograms/l and 131 +/- 11.7 micrograms/l in patients with steroid-sensitive and no rejection, respectively; fibronectin receptor: 1003 +/- 23.5 ng/ml vs 573 +/- 24.8 ng/ml and 428 +/- 13.6 ng/ ml in patients with steroid-sensitive and no rejection, respectively; and TGF-beta: 393 +/- 14.9 pg/ml versus 315 +/- 10.7 pg/ml and 233 +/- 8.9 pg/ml in patients with steroid-sensitive and no rejection, respectively. A further increase in hyaluronic acid levels was observed in patients who developed early chronic rejection, while fibronectin receptor and TGF-beta levels remained low, similarly to laminin levels. The increase in laminin, hyaluronic acid, fibronectin receptor, and TGF-beta during acute steroid-resistant rejection may be stimulated by the rejection-related release of cytokines and adhesion molecules which paralleled the increase in ECM parameters. The lack of increase in laminin and fibronectin receptor levels in those patients who developed early chronic rejection may reflect an inability to recover from acute rejection.

Acute Disease↗
PubMed1998

[Nephrolithiasis in "disk-variant" cross-over renal dystopia. Report of a case].

Renal dystopia is a frequent urogenital anomality. Renal dystopia encloses pelvic kidney or malascending kidney, but also rare anomalities like renal duplication or crossed renal dystopia. These allotopias are often diagnosed on routine examination of the urogenital system. We report a case with fused crossed renal dystopia on the left with atypical symptoms of nephrolithiasis and give a summery of the embryological origin.

Diagnosis, Differential↗
PubMed1992

Characterization of acetylcholine- and endothelin-induced calcium entry in cultured human ciliary muscle cells.

We characterized the effects of acetylcholine and endothelin on cultured human ciliary muscle cells, using the calcium-sensitive dye fura-2 to measure intracellular calcium and intracellular microelectrodes to measure the membrane potential. Both agonists, endothelin and acetylcholine, had a typical biphasic effect on the intracellular calcium concentration. Calcium peaked initially, because of its release from intracellular stores, and then reached a plateau, owing to entry of extracellular calcium. Endothelin-induced calcium entry was almost completely blocked by addition of extracellular La3+ (50 mumol/l) and Ni2+ (1 mmol/l). Acetylcholine-induced calcium entry was likewise almost completely abolished by La3+ and Ni2+. Both endothelin and acetylcholine led to an initial transient hyperpolarization with a subsequent depolarization. The hyperpolarization of the membrane potential had a time course similar to the initial calcium peak, while the depolarization occurred parallel to the calcium plateau. The depolarization induced by both agonists was reduced in the presence of La3+ and Ni2+. Verapamil (10 mumol/l) had no effect on either the calcium entry or the depolarization. Acetylcholine did not induce a [Ca2+]i peak when it was applied during the endothelin-induced [Ca2+]i plateau and vice versa. The [Ca2+]i plateau was not higher with concomitant than with single application of acetylcholine or endothelin. Thus, calcium entry and membrane depolarization induced by acetylcholine and endothelin seem to be mediated by a common La(3+)- and Ni(2+)-sensitive but verapamil-insensitive mechanism.

Acetylcholine↗