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Biomedical subjects

R Viebahn

Publications and source records attributed to R Viebahn.

48 records · Page 3Linked to original sources

[Pregnancy and labor following liver transplantation].

We report on pregnancy and delivery in a patient following hepatic transplantation. After an uneventful gestation at term, a child of normal body weight was born. To the best of our knowledge only 7 successful pregnancies following hepatic transplantation have been reported, one of them in the Federal Republic of Germany. Amongst the publications mentioned there are only two further reports on an immunosuppressive drug regimen utilising cyclosporine plus prednisolone. We stress the importance of the following items: peripartual immunosuppression, analgesia as well as the necessary control of the coagulation system.

Adult↗

[Surgical therapy of liver and bile duct tumors].

The most effective surgical therapy of primary liver cancer (HCC) or proximal bile duct cancer (BDC) is radical resection, but only 20% of the patients will undergo this procedure, because the remaining patients in the advanced tumour-stage or cirrhosis can be given palliative treatment only (chemo-embolisation for HCC, endoscopic or percutaneous draining with or without iridium-after-loading for BDC) or a liver transplantation (LTX), though under immunosuppression an early recurrence of the tumour is frequent. One-year survival after resection because of HCC without cirrhosis is represented by a figure of 80%, whereas with cirrhosis it is 18%; 3 years after LTX, 26% of patients are alive. Three-year survival in untreated BDC is 24%, after resection of the hilum 42%, after LTX 40%.

Bile Duct Neoplasms↗

Thymus carcinoid.

A carcinoid of the thymus was studied by light- and electron-microscopy, immunohistology and flow-cytometry. The tumor showed a ribbon- and festoon-like growth-pattern with foci of necrosis, invasion of vessels and infiltration of mediastinal lymph nodes. The cytoplasma of the tumor-cells contained neuroendocrine granula and immunohistochemistry of ACTH was positive. The tumor-cells were connected by desmosomes, correlating to a pre-keratin positive immunohistology. In flow-cytometry the tumor-cells showed a near haploid DNA aneuploidy which is an extremely rare finding in solid tumors and in the few cases described indicative for treatment resistance.

Carcinoid Tumor↗

Toxicity, uptake kinetics and efficacy of new transfection reagents: increase of oligonucleotide uptake.

Human arterial smooth muscle cell (haSMC) proliferation is stimulated by platelet-derived growth factor (PDGF) release of human arterial endothelial cells (haEC) whereas transforming growth factor-beta(1) (TGF-beta(1)) secretion by haSMC promotes extracellular matrix formation. Inhibitory concepts with antisense oligonucleotides (ASO) against those growth factors might be promising, requiring, however, sufficient transfection efficacy. Thus, toxicity and efficacy of new transfection reagents were examined. MTT tests showed that high doses >1.6 microg/ml of the liposome Cytofectin GSV((R)) (CF) and the dendrimer SuperFect (SF) reduced mitochondrial activity of haEC after > or =4 h transfection whereas viability of haSMC was not influenced. DAC-30((R)) showed significant toxic effects on haEC and haSMC at each dose after > or =4 h and Lipofectin((R)) (LF) caused complete detachment of haEC and haSMC in medium containing 10% serum. Uptake studies demonstrated that 'naked' ASO were not incorporated intracellularly whereas transfection within CF or SF resulted in a strong cytoplasmic and nuclear labeling after 2-5 h. With DAC-30, only a slight cytoplasmic fluorescence was found. SF caused an unexpected stimulation of endothelial PDGF-AB synthesis. Thus, CF was favored for inhibition studies. ELISA, Western and Northern blotting showed a significant inhibition of endothelial PDGF-B and smooth muscle TGF-beta(1) mRNA expression and synthesis after transfection for 3-5 h using 0.1-1.0 microM ASO versus control oligonucleotides. We conclude that Cytofectin GSV is superior to the other transfection reagents, predominantly at haEC, showing an improved efficacy and less toxicity than the classical liposome Lipofectin. Cytofectin GSV might offer a promising tool for antisense strategies in the treatment of vascular disorders.

Blood Vessels↗