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K Engelmann

Publications and source records attributed to K Engelmann.

81 records · Page 5Linked to original sources
PubMed1988

Isolation and long-term cultivation of human corneal endothelial cells.

Human corneal endothelial cells (HCEC) were isolated by means of enzymatic treatment of excised corneas. The corneas were incubated for 1.5 hr together with a high concentration of collagenase (0.5%), followed by a long-term incubation (up to 16 hr) using a low concentration of the enzyme (0.04%). Endothelial cells were enriched against contaminating fibroblasts by using a selective L-valine-free medium which inhibited fibroblast growth during the first passages. Subcultures of HCEC were passaged for more than 20 generations without showing signs of senescence. Laminin and chondroitin sulfate functioned as a substrate for HCEC, promoting proliferation and allowing the cells to grow in monolayer formation. The inclusion of fibroblast growth factor (FGF) as well as chondroitin sulfate in the medium led to an additional increase in the rate of proliferation.

Cells, Cultured↗
PubMed1987

Properties of poliovirus associated protein kinase.

Highly purified virulent poliovirus preparations harbour an endogenous protein kinase. Enzyme activity increases significantly upon purification of infectious virus particles from infected HeLa cells. Enzyme activity is stimulated by divalent cations. The substrate specificity and the degree of stimulation of the kinase are dependent on the nature of the divalent cations included in the assay. The preferred substrates for this kinase are the viral capsid proteins. Exogenously added proteins such as alpha-casein, phosvitin and protamine are also phosphorylated by the kinase. Moreover, these proteins enhance the phosphorylation of viral proteins. In the presence of Mg++ VP 2 and VP 0 are highly phosphorylated, while in the presence of Zn++ only VP 2 and VP 4, but not VP 0 or exogenous proteins are phosphorylated. Poliovirus associated protein kinase exhibits optimal activity at pH 7.9 in the presence of 10 mM Mg++. The Km for ATP is shown to be 40 microM. By testing different nucleotides as phosphate donors a specificity of the phosphorylation reaction for ATP is demonstrated. Phosphoamino acid analysis of hydrolysates of the substrates phosphorylated in the presence of Mg++ by thin layer electrochromatography and HPLC yielded phosphoserine and phosphothreonine from viral capsid proteins while hydrolysates of protamine yield only phosphoserine. Destabilization of the viral capsid, e.g. by preincubation at 42 degrees C for 20 minutes results in a stimulation of kinase activity. Moreover, phosphorylation of the poliovirus capsid proteins itself results in destabilization of the viral capsid. These findings suggest that phosphorylation of the viral coat proteins triggers or enhances the uncoating of poliovirus leading to the release of viral RNA.

Amino Acids↗
PubMedDate not supplied

Percutaneous MR imaging-guided laser-induced thermotherapy of hepatic metastases.

BACKGROUND: Many primary tumors may cause liver metastases, which are generally treated with surgical resection and/or chemotherapy. After resection of liver metastases in patients with colorectal carcinoma, 5-year survival rates are achieved in 25-38%, and two-thirds of patients will experience recurrent metastases. We examined percutaneous, minimally invasive, laser-induced thermotherapy (LITT) as an alternative outpatient procedure. Local tumor control rate and survival data were analyzed prospectively. METHODS: Between June 1993 and August 2000, 7148 laser applications were performed in 1981 lesions in 705 consecutive patients and 1653 treatment sessions. The complications of the procedure were evaluated by clinical examination and magnetic resonance imaging (MRI) and computed tomography. Local tumor control was evaluated by plain and contrast-enhanced follow-up MRI using T1- and T2-weighted spin-echo and gradient-echo sequences every 3 months after treatment. Cumulative survival times were calculated using the Kaplan-Meier method. RESULTS: The overall rate of complications and side effects was 7.5%. The rate of clinically relevant complications was 1.3%. Local tumor control rate after 3 months was 99.3%; 6 months after laser treatment, plain and contrast-enhanced MRI documented a local tumor control rate of 97.9%. In patients treated with MR-guided LITT for unresectable colorectal liver metastases, the mean survival was 41.8 months (95% confidence interval = 37.3-46.4 months). The 1-year survival rate was 93%, the 2-year survival rate was 74%, the 3-year survival rate was 50%, and the 5-year survival was 30%. In patients treated with LITT for liver metastases from breast cancer, the mean survival was 4.3 years (95% confidence interval = 3.6-5.0 years). CONCLUSION: In patients with liver metastases, local tumor destruction using minimally invasive, percutaneous LITT under local anesthesia results in improved clinical outcomes and survival rates and can be a potential alternative to surgical resection.

Adult↗