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Biomedical subjects

W Merk

Publications and source records attributed to W Merk.

12 recordsLinked to original sources
PubMed1988

Fermentation with immobilized cell cultures.

For the production of monoclonal antibodies and complex recombinant human proteins or glycoproteins a number of immobilized cell culture systems have been developed. The advantages of such cell culture systems are that cells can be kept in small volumes of cell culture fluid and media can be changed continuously if necessary for induction of product synthesis or removal and harvest of metabolic products. Whereas the hollow fiber and the opticell culture systems can be limited in scaling up the microcarrier system, the fluidized bed bioreactor and the solid bed bioreactor are suitable for scaling up. In contrast to the other systems, the solid bed bioreactor requires no special manipulation for anchoring the cells to the wire springs. In situ cleaning is possible and the beads are reusable. With this cell culture fermentation system, production processes for interferon beta, monoclonal antibodies for interferon alfa and recombinant human tissue plasminogen activator were developed.

Antibodies, Monoclonal↗
PubMed1987

Serum levels of free non-protein bound clofibrinic acid after single dosing to patients with impaired renal function of various degrees--a multicenter study.

As a basis for establishing dosing guidelines in order to avoid side effects due to overdosage, the concentrations of total and free non-protein bound clofibrinic acid (CA) were determined before and after the administration of a single clofibrate dose (0, 2, 6, 12, 24, 48, 72, 96h) in patients with various degrees of impaired renal function and in a control group (n = 56). The clofibrate doses administered to the five groups were: group 0 = control group without renal impairment: 1,000 mg; group 1 = serum creatinine up to 354 mumol/l: 1,000 mg; group 2a = creatinine levels greater than 354 mumol/l up to levels requiring dialysis: 1,000 mg; group 2b = creatinine levels like 2a, but only 500 mg; group 3 = patients requiring dialysis: 500 mg. In addition, serum albumin, CK, GOT and GPT were controlled. Total CA was determined by gas chromatography, the unbound fraction by equilibrium dialysis. Increasing serum creatinine levels were correlated with a decrease of total CA but with a statistically significant increase in free CA concentrations. The levels of non-protein bound CA of groups 1 and 2a were significantly different from control group 0 (same dosing). In addition, a significantly negative correlation between free CA and serum albumin levels was demonstrated. Determination of free CA as a control parameter of clofibrate therapy in patients with impaired renal function allows clofibrate dosing to be closer related to the individual subject than the determination of total CA only.

Adult↗
PubMed1986

Increased in vitro platelet aggregation in hypertriglyceridemias.

Platelet aggregation induced by ADP and collagen was monitored in 25 patients with increased serum levels of triglycerides (7 HLPs type IIb, 14 type IV, 4 type V patients) and compared with a group of 10 normolipidaemic control persons. Platelet aggregation was studied simultaneously in platelet rich plasma (PRP) by both turbidometric and impedance technique and also in whole blood (WB) by the impedance method. Whereas platelet aggregation testing by turbidometry was limited by the optical density of the plasma samples in hypertriglyceridemia, the aggregation process could easily be registered in PRP and WB using the impedance method. Threshold aggregatory concentrations with both agonists were significantly lower for all three groups of HLP.

Adenosine Diphosphate↗
PubMed1986

Fenofibrate and colestipol: effects on serum and lipoprotein lipids and apolipoproteins in familial hypercholesterolaemia.

Effects on serum lipoproteins were studied in ten patients with familial hypercholesterolaemia (FH) during consecutive eight-week treatment periods with fenofibrate 0.3 g/day, fenofibrate plus colestipol, 15 g/day, and fenofibrate 0.25 g/day plus colestipol. VLDL, LDL, HDL, HDL2, and HDL3 were isolated by ultracentrifugation and precipitation. Lipids and apolipoproteins A-I and B were determined by enzymatic and immunonephelometric techniques, respectively. Administration of fenofibrate alone resulted in decreases in VLDL and LDL cholesterol (-48% and -18%) and in serum apolipoprotein B (-10%), but in increases in HDL, HDL2, and HDL3 (+25%, +26%, and +24%), and in serum apolipoprotein A-I (+6%). Addition of colestipol produced a further reduction in LDL cholesterol (-31%) and in serum apolipoprotein B (-19%). The effects were maintained with less fenofibrate. In FH, an acceptable therapy combines the favourable effects of sufficient lowering of LDL and of a rise in HDL.

Adult↗
PubMed1985

Recombinant HuIFN-gamma prevents herpes simplex keratitis in African green monkeys: demonstration of synergism with recombinant HuIFN-alpha 2.

Human interferon gamma (HuIFN-gamma) was found to prevent herpes-simplex virus (HSV 1) induced keratitis in monkey eyes, when administered topically at concentrations of greater than or equal to 3 X 10(5) reference units/ml. Protective efficacy demonstrated with lower concentrations of HuIFN-gamma in combination with low titers of HuIFN-alpha provided evidence of synergistic interferon activity in vivo. Tolerance problems observed in eyes affected by virus inoculation seem to be attributable to the experimental conditions including species heterology.

Animals↗
PubMed1985

Immunoassay for the quantitation of human leukocyte interferon.

A sensitive nonradioactive immunoassay based on monoclonal antibodies was developed. A number of monoclonal hybridomas secreting antibodies against human leukocyte interferon (IFN alpha) were generated using mice immunized with purified lymphoblastoid IFN. Although the binding of antibody to IFN alpha was used as one criterium of selection, all antibodies found can neutralize its antiviral activity. A pair of antibodies binding to different regions of IFN alpha was identified. These were incorporated into sensitive sandwich assays of IFN alpha. A microtiter plate assay - using horse radish peroxidase as marker enzyme - is able to detect IFN alpha at a concentration of 30 IU/ml within 5 h. An overnight tube assay can detect approximately 30 pg IFN alpha 2 or 3 IU per ml solution. The 5-h ELISA (enzyme-linked immunosorbent assay) is well suited for the monitoring of the recovery of rIFN alpha from recombinant organism, during purification and refinement of the protein to a therapeutic drug.

Antibodies, Monoclonal↗
PubMed1984

Effect of fenofibrate on serum lipoproteins in subjects with familial hypercholesterolemia and combined hyperlipidemia.

The effects on serum lipoproteins were studied in 8 patients with familial heterozygous hypercholesterolemia and 9 patients with familial combined hyperlipidemia during an 8-week treatment with fenofibrate. VLDL, IDL, LDL and HDL were isolated by ultracentrifugation and precipitation. Lipids and apolipoproteins A-I and B were determined by enzymatic and immunonephelometric techniques, respectively. In hypercholesterolemia, administration of fenofibrate resulted in decreases of VLDL, IDL, and LDL (cholesterol -58.3%, -28.6%, and -24.4%), while, in combined hyperlipidemia, treatment with the drug lowered VLDL and IDL (-33.3% and -42.9%). HDL cholesterol and apolipoprotein A-I increased only in hypercholesterolemia (+22.9% and +6.9%).

Adult↗
PubMedDate not supplied

Prediction of multicomponent adsorption behavior in activated carbon adsorbers: kinetic aspects.

Although the concentrations of solutes are very low in water treatment, it cannot be expected that the film-diffusion model predicts breakthrough behavior satisfactorily, for the following reasons: most of the solutes have less favorable isotherms than p-nitrophenol or p-chlorophenol; many solutes are much larger molecules and hence have a much higher internal diffusion resistance than p-nitrophenol or p-chlorophenol; and displacement effects cause a much higher internal resistance than expected from single-solute data. Therefore, internal diffusion resistance has to be incorporated into the film-homogeneous diffusion model. All parameters needed in this model can be obtained from batch reactor tests. Multi-solute systems may be regarded as a single-solute system or a bi-solute system, respectively, if all solutes except one or two are present in very different concentrations; and/or have a comparatively small affinity to activated carbon; and/or have a comparatively small internal diffusion coefficient.

Adsorption↗