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Biomedical subjects

K Kopp

Publications and source records attributed to K Kopp.

At least 19 recordsLinked to original sources
PubMed1998

Appropriate mammalian expression systems for biopharmaceuticals.

Process development for biopharmaceuticals is dictated by product quality, drug safety and economy of the manufacturing process. Not surprisingly, these factors also play a key role in the evaluation of mammalian cell expression systems to be used in the production of pharmacologically active glycoproteins. To date, the most prominent candidates for efficient expression of glycoproteins are mammalian cell lines such as mouse fibroblast cells (C 127-BPV), Chinese hamster ovary cells (CHO-DHFR, CHO-NEOSPLA, CHO-GS), mouse myeloma cells (NSO-GS) as well as transgenic animals carrying c-DNA or genomic DNA which codes for the protein of interest. The expression titer in the case of glycoproteins is mainly determined by the promoter construct, the site of integration into the chromosome, the copy number and the type of protein in question. Based on expression titer, CHO-NEOSPLA and NSO-GS expression systems are most effective in the production of monoclonal antibodies and, to a lesser extent, of recombinant DNA derived proteins. However, based on overall product yield, expression of recombinant DNA derived proteins in transgenic animals is by far the most promising system. Therefore, for proteins required in large quantities, transgenic expression systems offer an attractive choice. However, cost of goods for products for which the dosage or the overall annual quantities are low, is dominated by downstream processing, filling, lyophilization and packaging and not by the fermentation process. Such proteins are preferentially produced by classical mammalian cell culture systems. Concerns which have to be addressed with respect to drug safety in the transgenic animal approach are the size of the herd, genetic stability from animal to animal, variation in productivity and in impurity profiles during lactation periods, microbial, viral, mycoplasma and prion contaminants, the dependence on health status and the life span of the animal. In a number of cases glycosylation of the protein is relevant for the prevention of immunogenicity of the protein, the pharmacological activity, the pharmacokinetic profile, solubility and stability against proteolysis. The glycosylation pattern, depending on protein structure, is influenced by the enzymatic system of the host cell as well as by fermentation conditions. Therefore, selection of host cells and culture conditions must take into account the requirement for a specific and stable glycosylation pattern. For the assessment of glycovariants, a number of protein analytical methods such as peptide mapping, isoelectric focusing, oligosaccharide mapping, MALDI-TOF (matrix assisted laser desorption mass spectrometry-time of flight), capillary electrophoresis and specific potency assays are available. In our experiments, glycosylation of proteins expressed in CHO cells was demonstrated to be very stable. Only extreme process times, cultivation methods and ammonium ion concentrations had an influence on the glycosylation profile. Among the three products investigated--tissue plasminogen activator (t-PA), interferon omega and soluble intercellular adhesion molecule (s-ICAM)--t-PA expressed the most stable glycosylation pattern. Only at extreme ammonium concentrations an increase of mannose-5 structures was observed, whereas biantennary complex structures were reduced. On the other hand, interferon omega and s-ICAM showed greater susceptibility to increased ammonium concentrations and to adherent cultivation. Such conditions induced quantitative changes to the glycosylation pattern favoring the appearance of higher branched structures. Short cultivation times resulted in more heterogenous oligosaccharide structures. Since the glycosylation of the three proteins is different in the same host cell, the amino acid sequence of the protein apparently influences the glycosylation pattern and its sensitivity to culture conditions. In NSO-mouse myeloma cells, production of s-ICAM is two times as high as in CHO cells

Animals↗
PubMed1996

Monitoring the glycosylation pattern of recombinant interferon-omega with high-pH anion-exchange chromatography and capillary electrophoresis.

The enzymatic glycosylation of certain asparagine residues in the protein structure has a profound influence on their physico-chemical properties. Many recombinant DNA derived glycoprotein pharmaceuticals for therapeutic use are glycosylated. Their oligosaccharides are important with regard to stability, solubility, in vivo activity and antigenicity. Sophisticated analytical methods that allow a high resolution of synthesized carbohydrate structures are therefore necessary to ensure a constant product quality. To elucidate the robustness of interferon-omega glycosylation regarding process modifications. Chinese Hamster Ovary (CHO)-cells expressing human interferon-omega were cultivated under different fermentation conditions. The most significant glycosylation alterations resulted from the varied parameters such as initial ammonia concentration in the production medium, cultivation mode (adherent versus suspended) or process time. These are detectable with HPAEC (high-pH anion-exchange chromatography) oligosaccharide mapping as well as with capillary electrophoresis.

Animals↗
PubMed1995

Hyalomma truncatum (Acari; Ixodidae): evidence for the inability of adult ticks to discriminate between colours.

Behavioural investigations into the perception and differentiation of coloured objects by unfed adult Hyalomma truncatum ticks revealed that silhouettes of blue, green, red and yellow colour, under illumination by a sun-simulating waveband spectrum, are perceived by the ticks and responded to equally by a directed response. Two green or dark grey rectangles each with a luminance contrast ratio of 5:1 against the white wall of the test arena in combination with an overlapping, equally sized dark grey or green target were consistently reached by ticks in a ratio of 2:1. Since the outer targets were occupied by the double number of ticks compared with the central silhouette this shows that the response is independent of the colour of the object. Investigations into target perception under monochromatic radiation of different wavelength ranges which were evenly adjusted in their irradiances revealed that ticks responded equally to a black target irradiated by blue, green, yellow and red light of wavelengths 428-472, 517-563, 549-591 and 606-654 nm, respectively. These results indicate the lack of true colour vision in H. truncatum.

Animals↗
PubMed1995

Hyalomma truncatum (Acari; Ixodidae): investigations into the scototaxis of unfed adult ticks.

Under controlled test conditions, unfed male and female Hyalomma truncatum ticks exhibited a positive scototaxis to stationary, two-dimensional targets. Upright-positioned rectangles were the most attractive targets. The attractiveness of these targets increased with their size. Significantly more ticks responded scototactically positively to the targets under a luminance contrast ratio of 5:1, as compared with other luminance contrast ratios. Targets with an elevation angle of 13 degrees were occupied more frequently than objects with higher elevation angles. Scototaxis was the same towards a stationary and a sinusoid oscillating target. When an upright-positioned rectangle was combined with a CO2 gradient, the number of ticks that migrated into the CO2 gradient and contacted the target did not increase significantly. The interval between exposure and first locomotion of the ticks, however, was significantly shorter under the influence of a CO2 gradient than in all other experiments without a CO2 gradient. A temperature gradient simulating a natural host (cattle) did not alter the scototaxis. The results of these investigations suggest that the positive scototaxis exhibited by adult H. truncatum ticks is not likely to be part of their appetence behaviour but rather searching behaviour to find adequate protection from harsh climatic conditions.

Animals↗
PubMed1994

Biochemical and immunohistochemical multiparametric analysis of steroid receptors and growth factor receptors in human normal endometrium in spontaneous cycles and after the induction of ovulation.

This study was carried out with three aims: to assess the variations of receptors for beta-oestradiol and progesterone, and for epidermal growth factor (EGF), alpha-fibroblast growth factor (FGF) and beta-FGF, during a spontaneous cycle in normo-ovulatory patients, 2 days before, and 2 and 7 days after the day of ovulation; to compare the control group of patients with those given ovulation induction using a multiparametric approach; and to study the role of luteal supplementation with progesterone in two groups of patients treated by a luteinizing hormone-releasing hormone agonist plus human menopausal gonadotrophin. The results were assessed by biochemical analyses and by immunohistochemistry. In spontaneous cycles, a decrease in steroid receptors occurred during the luteal phase. There was an increase in EGF and EGF receptors which was induced by oestradiol secretion, and an increase during the luteal phase of alpha-FGF and beta-FGF, which are considered to be angiogenic factors. Comparisons between spontaneous and induced cycles showed a few variations in the endometrium but no differences were related to the type of ovulation induction.

Adult↗
PubMed1991

[Patients coping with cancer. A review].

The expression coping is defined. Theoretically, coping is described as either unconscious ego defences or as an expression of concious process. The literature which employs the expression coping in connection with cancer is described. Several methodological problems exist. The initial criteria, the nature of the disease and the time of diagnosis and various types of treatment are some of the factors which inhibit the quality of the investigation. In addition, no discussion is available about the extent to which scientific methods can be employed in assessing the process of coping. Only few investigations are concerned with intervention but the results suggest that it is possible to improve cancer patients' ability to cope with the problems which develop on account of the diagnosis and subsequent treatment. Further investigation of the expression, the methods of investigation and intervention are necessary to elucidate the employability in clinical practice.

Adaptation, Psychological↗
PubMed1989

Parathyroid hormone inhibits collagen synthesis at both ribonucleic acid and protein levels in rat osteogenic sarcoma cells.

Cells of the clonal rat osteogenic sarcoma cell line, UMR 106-01, were used to investigate the regulation of collagen synthesis by PTH in osteoblastic cells. Monolayer cultures of cells were labeled with [3H] proline in order to determine both collagen type and rates of production. Analysis of labeled extracellular polypeptides on sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that UMR 106-01 cells synthesized predominantly type I collagen, accounting for 45.48 +/- 2.09% of the radioactivity incorporated into total protein. After 24-h treatment with bovine PTH (1-34, 10(-8) M), collagen synthesis (i.e. collagenase-digestible protein) was decreased to 29.45 +/- 1.39% of total protein production. This decrease was first observed 12 h after addition of hormone and greatest inhibition was achieved at 24 h. The effect of PTH was dose dependent, with half-maximal inhibition of collagen synthesis occurring at 5 x 10(-10) M after 24-h treatment. In contrast, when steady state levels of mRNA for type I collagen chains were examined by Northern blot analysis, the concentration of PTH that reduced collagen synthesis by 35-45% (10(-8) M), caused a net decrease of approximately 80-96% in the number of procollagen transcripts; a small reduction in beta-actin mRNA levels was also observed. The effect of the hormone on procollagen message level was dose dependent, with significant inhibition observed at 10(-10) M PTH and, as with collagen synthesis, maximal after 24 h.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

[Late results of Küntscher medullary nailing of femoral and tibial fractures in the still growing skeleton].

This is a report about the clinical and roentgenological results of 11 patients who had single lower-leg fractures (average age at times of operation 15.6 years) average 4.8 years after medullary nailing, and about 11 patients with single femoral fractures (average age at times of operation 13.3 years) average 6.4 years after the operation. The Küntscher-nail had already been removed. Beside inquiring subjective statements we checked the possible influence of medullary nailing on the still growing skeleton. We did not find any severe faults in axis or rotation. Acceleration or retardation of bone growth were mainly found in younger patients (10-12 years of age at first operation), in distal localised fractures or in case of longer pre- or intraoperative bone reduction. We did not find essential differences in length of the legs in cases where the fractures had been nailed during the final period of bone growth (15-17 years).

Adolescent↗
PubMed1982

[Results of treatment of fresh traumatic dislocation of the shoulder].

This is a report about the treatment and the results of 100 patients with primary traumatic dislocations of the shoulder. Dependent on the age of the patient the shoulder was kept in place after the reduction either by a shoulder-arm-plaster-cast for 3 weeks or by Desault's bandage for 4-7 days. 68 patients were controlled clinically and roentgenologically 1-6 years after the dislocation. The sight was kept on the function of the joint, on the development of calcifications of the capsule and on the occurrence of recurrent dislocations.

Adolescent↗
PubMed1981

[Arthroscopy of the knee joint (author's transl)].

The clinical application of the arthroscopy is described. The results of 300 cases are evaluated and discussed. There is a striking discrepancy between the clinical diagnosis before and after arthroscopy. The clinical diagnosis of a damage to the meniscus seems less reliable; the value of arthrography is limited, too. As conclusion it can be stated that the results presented favour a generous use of arthroscopy. More often arthroscopies will be performed after fresh injuries of the knee joint.

Arthroscopy↗