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J Kopp

Publications and source records attributed to J Kopp.

At least 91 records · Page 5Linked to original sources
PubMed1988

Direct comparison of electric field-mediated and PEG-mediated cell fusion for the generation of antibody producing hybridomas.

As an alternative to polyethylene glycol (PEG), electric field pulses offer, in theory, fusion conditions whose parameters are better controllable. In 1985 (1) we reported on the successful generation of hybridoma clones by means of electrofusion performed in a batch-type manner similar to that usually employed with PEG, and applicable to any type of antigens. Here we summarize the results of a series of fusions performed since then in which both electric field and PEG induced fusion were directly compared. Different types of antigens were used. Electrofusion resulted in a 3.8 to 33.0 times higher yield of hybridomas per unit number of spleen cells. Moreover, hybridomas grew more vigorously after fusion and, therefore, were earlier visible. Other parameters examined revealed no differences between hybridomas generated by either method.

Animals↗
PubMed1986

Simple preparative two-step purification of interleukin-2 from culture medium of lectin stimulated normal human lymphocytes.

A procedure has been developed for the rapid purification of human IL-2 using reversed-phase liquid chromatography on LiChroprep RP-8 and Separon SGX C-18. The resulting IL-2 has a specific activity of 1 X 10(7) U/mg protein and reveals in SDS-PAGE 2 molecular weight forms (approximately 14 kDa and approximately 16 kDa) under reducing and non-reducing conditions. Both forms are biologically active. In 2-dimensional electrophoresis purified IL-2 shows a complex pattern of protein spots located in the IL-2 region which may be due to differences in glycosylation.

Chromatography, Liquid↗
PubMed1986

Correlation between the phenotype and the functional capacity of activated T cells in patients with active systemic lupus erythematosus.

Activated T cells in the peripheral blood of patients with systemic lupus erythematosus (SLE) were determined using monoclonal antibodies against activation antigens. Elevated percentages of HLA-DR+ T cells were found in association with active disease. In contrast, we observed an increase in IL-2 receptor-bearing T cells in only six out of 16 patients with active disease. In vitro assays, like spontaneous proliferation, response to IL-2, production of IL-2, and immunoglobulin synthesis have shown that the different patterns of activation antigens are related to different functional stages of T-cell activation. The possible therapeutic consequences are discussed.

Antigens, Surface↗
PubMed1986

Amphibian optokinetic after nystagmus: properties and comparative analysis in various species.

Optokinetic nystagmus and after nystagmus were studied in six amphibian species, three urodeles and three anurans. It was demonstrated that two of the urodeles, Hydromantes italicus and Salamandra salamandra, display a relatively well-developed optokinetic after nystagmus, which is less pronounced in Bombina variegata and nearly absent in Bufo bufo, Rana temporaria, and Tylototriton verrucosus. These results indicate a certain degree of velocity storage in the optokinetic reflex of some amphibians.

Amphibians↗
PubMed1985

Influence of magnesium deficiency on liver collagen after carbon tetrachloride or ethanol administration to rats.

The effects of magnesium deficiency on liver collagen after the administration of a hepatotoxic substance were investigated. Rats, fed a control or magnesium-deficient diet (0.040 g/kg), received six CCl4 or mineral oil injections administered at 2-d intervals starting from the first day of diet treatment. They were killed 3 or 12 d after the last injection. Between postinjection d 3 and 12, no change of magnesium concentration in liver was observed in the deficient rats. Three days after the end of treatment liver calcium in the magnesium-deficient CCl4-treated rats was higher than in any other group. Liver collagen of untreated control rats and untreated magnesium-deficient rats was not significantly different. In control and magnesium-deficient animals receiving CCl4 treatment, the liver collagen levels were significantly higher than in untreated rats. The magnesium-deficient rats receiving CCl4 have higher liver collagen than the controls receiving CCl4. In a second experiment the effect of suboptimum intake of magnesium (0.120 g/kg) combined with the ingestion of ethanol was studied in rats given a solution of ethanol in water for 55 d as their only source of fluid. Mortality occurred in the magnesium-deficient rats receiving ethanol, and body weights of these rats were lower than those of animals in the other three groups. The collagen concentration in liver was higher in magnesium-deficient rats consuming ethanol than in any other group. The synergistic action between magnesium deficiency and ethanol therefore appears to be analogous to that observed with CCl4.

Animals↗
PubMed1984

Quantitative analysis of salamander horizontal head nystagmus.

The horizontal optokinetic head nystagmus of salamanders (Salamandra salamandra) was investigated at various constant and sinusoidally modulated velocities. With constant velocities the best compensation (head velocity/stimulus velocity) measured was 0.6 at a stimulus velocity of 3 deg/s. With slow stimuli up to 5 deg/s, small oscillations in the slow phase of the nystagmus occurred. The nystagmus started with a delay of 1.1 s after onset of stimulus with an acceleration period of up to 6 s. After the stimulus terminated, the head was decelerated within (on average) 5 s, indicating a weak velocity storage element. The nystagmus frequency, the acceleration time, and the deceleration time were in correlation with the head velocity during the slow phase. With sinusoidal stimuli, nonlinearities were displayed: the gain was amplitude-dependent, and distortions of the sinusoidal head movements occurred with higher frequencies.

Animals↗
PubMed1983

Prospective study of alcoholism treatment. Eight-year follow-up.

One hundred patients admitted for alcohol withdrawal were followed for eight years. At the eight year mark, 25 percent had achieved stable abstinence of three years' duration or more, and 29 percent had died. Only 26 percent experienced continued serious problems with alcohol. Premorbid social stability and sustained abstinence made independent contributions to good psychosocial outcome at eight years. Premorbid social stability and Alcoholics Anonymous attendance made independent contributions to sustained abstinence. Review of these data and other major longitudinal studies suggests that factors other than professionally organized treatment per se exert substantial effect upon long-term outcome.

Alcoholism↗
PubMed1982

Monoclonal antibodies against different antigenic determinants of a protein molecule (human serum albumin) as detected after labeling the antigen with two different markers.

By using FITC- and 125I-labeled human serum albumin (HSA) the reactivity of anti-HSA hybridoma antibodies was compared in solid-phase immunofluorescence assay (SIFA) and radioimmunoassay (SRIA). A considerable number of hybridoma antibodies had been detected which are positive in SIFA but not in SRIA. Since this cannot be explained by a difference in the sensitivity of the assays it seems likely that these monoclonal antibodies detect antigenic determinants which contain tyrosine as an essential part.

Animals↗
PubMed1982

Winding anomalies in nuclear DNA from malignant cells. I. Experimental evidence.

The superhelical properties of nuclear DNA from malignant cells of human origin (leukemic cell lines Reh and D-562, mesothelioma cell line, and peripheral blood monocytes from acute monocytic leukemia) were investigated in neutral sucrose gradients with ethidium bromide. As compared with the universal superhelical density of nuclear DNA from normal cells, the DNA released from malignant cells showed a substantially higher negative superhelix content, equivalent to an increased deficiency in right-handed DNA duplex turns. In regard to analogous results obtained from other malignant cell systems, the extremely underwound structural state of nuclear DNA appears to be a feature common to malignant cells.

Cell Line↗
PubMed1982

[Germination of Clostridium oncolyticum in spheroid cell cultures as an in vitro tumor model].

An aggregation technique is used for construction of multicellular spheroids from trypsinized cell cultures of several normal and cancerous cell lines. This technique is applicable also in the presence of 1 X 10(9)/ml spores of Clostridium oncolyticum, and spores and vegetative bacterial cells can be counted by a soft agar colonization technique after trypsinization of spheroids. 24 hours after aerobic cultivation of spore-containing spheroids, germination and multiplication of Clostridium is detected by microscopy, electron-microscopy, and by bacterial cultivation technique. In this response there was no considerable difference between spheroids from tumour or from fresh cell lines. By electron microscopy many spores and vegetatively multiplying Clostridia became visible in the central necrotic part of spheroids. In the peripheral aerobic rim of spheroids, however, also few vegetative Clostridia were detectable.

Cell Aggregation↗
PubMed1979

Effects of magnesium deficiency on parturition and uterine involution in the rat.

The effects of moderate magnesium deficiency on the outcome of pregnancy, the process of parturition and uterine involution, were studied in successive experiments using Sherman rats. Females were fed purified diets containing 0.110 or 1.500 g Mg/kg throughout pregnancy and lactation. This magnesium deficient diet decreased the plasma magnesium but did not affect the number of pregnant rats or the weight of females at parturition. There was no change in the weight and size of litter. The number of still births was not significantly increased. The parturition process was observed; abdominal contractions were less obvious in deficient animals than in controls, and they were often not noticeable. Parturition was slightly lengthened in deficient rats. The major effects of magnesium deficiency occurred during lactation when the dam lost weight and the growth of her young was reduced. The uterine weight and its collagen content was higher and the collagen solubility was lower in the deficient rats than in controls between 2 and 10 days post partum. The delay in uterine involution could be prevented by provision of a magnesium supplement after parturition.

Animals↗