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Biomedical subjects

C Koch

Publications and source records attributed to C Koch.

At least 397 records · Page 22Linked to original sources
PubMed1986

Human complement component C2: production and characterization of polyclonal and monoclonal antibodies against C2.

Rabbit antibodies to human complement component C2 were produced by immunization of rabbits with precipitates from line immunoelectrophoresis, and the antibodies were used to monitor a classical chromatographic purification of C2 and for affinity purification of C2. Twelve monoclonal antibodies with specificity for human complement component C2 were produced by fusion of myeloma cells with spleen cells from mice immunized with the affinity purified C2. The specificity of the monoclonal antibodies was confirmed by their reaction with antigen-antibody precipitates where C2 was the antigen, and by their specific reaction with C2 after separation in SDS-PAGE followed by immunoblotting. The affinity of the monoclonal antibodies varied as demonstrated by the titration curves in ELISA. The antibodies will be of importance for immunospecific purification of human C2 and C2 fragments, for specific depletion of C2 from human serum, and for quantification of C2 for clinical purposes.

Animals↗
PubMed1986

Biological effects of heavy ions in Arabidopsis seeds.

Irradiation of dry seeds of Arabidopsis with heavy ions (HZE-particles) produced by UNILAC-accelerator (GSI, Darmstadt) yielded aberrations in varied developmental endpoints such as survival rate and embryo vitality. The damage increased with particle density and charge. Cross sections in the range of 0.2-1.0 micrometer2 for Ne and Ar and 2.0-10.0 micrometers2 for Xe were estimated. Soaked seeds were more sensitive than dry seeds (cross-section 2.0-10.0 micrometers2 for Ar). The induced total damage in the irradiated seeds was estimated adding the different damages weighted by certain factors. These results will be used as base data for the interpretation and evaluation of spaceflight experiments on the biological effects of cosmic radiation.

Arabidopsis↗
PubMed1986

Analog "neuronal" networks in early vision.

Many problems in early vision can be formulated in terms of minimizing a cost function. Examples are shape from shading, edge detection, motion analysis, structure from motion, and surface interpolation. As shown by Poggio and Koch [Poggio, T. & Koch, C. (1985) Proc. R. Soc. London, Ser. B 226, 303-323], quadratic variational problems, an important subset of early vision tasks, can be "solved" by linear, analog electrical, or chemical networks. However, in the presence of discontinuities, the cost function is nonquadratic, raising the question of designing efficient algorithms for computing the optimal solution. Recently, Hopfield and Tank [Hopfield, J. J. & Tank, D. W. (1985) Biol. Cybern. 52, 141-152] have shown that networks of nonlinear analog "neurons" can be effective in computing the solution of optimization problems. We show how these networks can be generalized to solve the nonconvex energy functionals of early vision. We illustrate this approach by implementing a specific analog network, solving the problem of reconstructing a smooth surface from sparse data while preserving its discontinuities. These results suggest a novel computational strategy for solving early vision problems in both biological and real-time artificial vision systems.

Humans↗
PubMed1986

An epidemic spread of multiresistant Pseudomonas aeruginosa in a cystic fibrosis centre.

Early in 1983 an epidemic of a Pseudomonas aeruginosa resistant to aminoglycosides, carbenicillin, ureidopenicillins, ceftazidime, cefsulodin and imipenem occurred in a cystic fibrosis centre. Most of the epidemic could be attributed to a specific nosocomial strain by means of O-grouping and phage-typing. This strain was present in the centre at a low frequency in 1973 and developed resistance during courses of chemotherapy. The epidemic was stopped by isolating patients with the resistant strains. Restrictive and selective use of antibiotics have not been sufficient to eradicate the resistant strains, which persist in 42% of the patients. The extensive use of the third generation cephalosporins in the clinic is probably responsible for inducing and selecting for the resistant strains. Clustering of patients in the centre has facilitated the spread. First-line use of older beta-lactam antibiotics, close bacteriological monitoring and prompt isolation of patients with resistant strains are recommended.

Adolescent↗
PubMed1986

Sultamicillin--a new antibiotic in the treatment of persistent lower respiratory tract infections caused by Haemophilus influenzae.

Haemophilus influenzae is a frequent cause of recurrent or chronic lower respiratory tract infections in patients suffering from cystic fibrosis (CF) and other chronic obstructive pulmonary disease (COPD). Ampicillin and its derivatives are routinely used in treatment, but resistant strains producing beta-lactamase frequently necessitate the use of other antibiotics. Sultamicillin is a compound agent for oral use in which ampicillin and the beta-lactamase inhibitor sulbactam are linked as a double ester. This combination is active in vitro against many beta-lactamase producing bacteria including ampicillin-resistant H. influenzae. Eight CF children and ten children with other COPD suffering from chronic or recurrent H. influenzae infection of the lower respiratory tract were treated with sultamicillin orally, 25 mg/kg, 12-hourly, for two weeks. Nine infections were caused by ampicillin-resistant strains. At the end of the treatment 65% of the patients were free of H. influenzae. The only adverse reaction was diarrhoea which occurred in 14 patients, and necessitated withdrawal of one patient from the study.

Adolescent↗
PubMed1986

Specific diagnosis of exogenous bronchial asthma in children.

Twenty-six children with exogenous asthma were studied by case history (CH), skin tests (ST), allergen-specific serum IgE (RAST), basophil histamine release (HR), and bronchial provocation tests (BPT). Nine standardized allergens were used from the following groups: house dust mite, animal dander, pollen, and mould fungi. For each allergen, the same batch was used throughout for all in vivo and in vitro studies, and the tests were carried out in a controlled, double-blinded manner, independent of each other. Different allergen concentrations were used and the results graded on a semi-quantitative scale. Approximately 120 comparable investigations, using in vivo and in vitro tests were carried out, followed by calculations of the sensitivity and specificity for each test alone, as well as for various combinations of tests, at various allergen-concentrations, and compared with the result of BPT, i.e. the true diagnosis. In this way the results could be used to directly compare the diagnostic value of each test, and combinations of tests. In general, a careful CH combined with ST gave the most reliable results. RAST was the most unreliable single analysis. When pollen or mite allergy was suspected, a combination of ST with either RAST or HR gave a further diagnostic reliability. HR as a single analysis did not seem to offer advantages over existing methods. None of the tests, or combinations of tests offered 100% sensitivity and specificity. By altering the concentration of allergen, the sensitivity, or specificity could be increased, but only at the expense of a decrease in the other. BPT is still necessary in many instances when a specific diagnosis is required.

Adolescent↗
PubMed1986

Influence of bacterial endotoxins on basophil histamine release. Potentiation of antigen- and bacteria-induced histamine release.

The histamine-releasing capability of lipopolysaccharides (LPS) was examined in human leukocyte suspensions. LPS alone did not release histamine, but was found to enhance the histamine release caused by anti-IgE. Also the IgE-mediated histamine release caused by specific antigens (allergens or bacteria) in sensitized individuals was enhanced by LPS. The potentiating effect of LPS was observed in grass pollen and dog dander allergic patients as well as in patients sensitized to E. coli or Staph. aureus bacteria. No potentiation was obtained by exposure to unspecific allergens or bacteria to which the persons were not sensitized. Bacteria can release histamine by immunological or nonimmunological mechanisms, and only the immunological histamine release was found to be potentiated by LPS. It is speculated that endotoxins reinforce release of histamine caused by allergens in allergic patients or by bacteria in persons sensitized to these microorganisms.

Allergens↗
PubMed1986

Slow synaptic transmission in frog sympathetic ganglia.

Bullfrog ganglia contain two classes of neurone, B and C cells, which receive different inputs and exhibit different slow synaptic potentials. B cells, to which most effort has been directed, possess slow and late slow EPSPs. The sEPSP reflects a muscarinic action of acetylcholine released from boutons on B cells, whereas the late sEPSP is caused by a peptide (similar to teleost LHRH) released from boutons on C cells. During either sEPSP there is a selective reduction in two slow potassium conductances, designated 'M' and 'AHP'. The M conductance is voltage dependent and the AHP conductance is calcium dependent. Normally they act synergistically to prevent repetitive firing of action potentials during maintained stimuli. Computer stimulation of the interactions of these conductances with the other five voltage-dependent conductances present in the membrane allows a complete reconstruction of the effects of slow synaptic transmission on electrical behaviour.

Animals↗
PubMed1986

Immediate and prolonged clinical efficacy of ceftazidime versus ceftazidime plus tobramycin in chronic Pseudomonas aeruginosa infection in cystic fibrosis.

20 patients with cystic fibrosis and chronic bronchopulmonary infection due to Pseudomonas aeruginosa entered a randomized cross-over study comparing ceftazidime (150 mg/kg body weight/24 h) plus tobramycin (10 mg/kg body weight/24 h) to ceftazidime alone (150 mg/kg body weight/24 h), both given intravenously for 2 weeks. 17 patients completed the study; both treatment regimens improved lung function and decreased the WBC count. No difference in clinical efficacy was found between the treatments. Pulmonary function returned to pre-treatment levels 3 months later with no difference between the treatments. No changes were seen in minimal inhibitory concentrations during treatment. None of the patients developed hypersensitivity or experienced serious adverse reactions to the drugs.

Adult↗
PubMed1986

A comparative study of amoxycillin and pivampicillin in persistent Haemophilus influenzae infection of the lower respiratory tract in children with chronic lung disease.

A double-blind cross-over study was undertaken to compare the efficacy of amoxycillin and pivampicillin on Haemophilus influenzae infection of the lower respiratory tract in children. 20 patients with cystic fibrosis (CF) or chronic obstructive pulmonary disease (COPD) due to other causes were included in the study. All patients had a history of regularly harbouring H. influenzae in sputum and repeated treatment failures with pivampicillin. 18 completed two 14-day courses in random order with equimolar doses of pivampicillin (80 mg/kg/day) and amoxycillin (62 mg/kg/day). Both drugs were well tolerated with no serious side effects, but pivampicillin was associated with more pronounced nausea. In steady state the mean serum concentrations of antibiotics 2 and 4 h after medication were 9.7 and 3.7 micrograms/ml for pivampicillin and 19.1 and 7.9 micrograms/ml for amoxycillin (p less than 0.01). Eradication of H. influenzae and clinical improvement was seen in one-third of the courses with both drugs. Betalactamase producing ampicillin-resistant strains emerged during 58% of the amoxycillin courses, but only in 16% of the pivampicillin courses (p less than 0.001). The high number of treatment failures and the development of resistant strains indicate that betalactamase inhibitors may possibly improve the efficacy of these drugs, especially of amoxycillin, in these patients.

Adolescent↗
PubMed1986

Bacteria and their products release histamine and potentiate mediator release: new aspects in airway diseases.

The possibility that bacteria and their products play a role in airway diseases, due to their capacity to release histamine, was investigated in blood leucocytes from patients suffering from respiratory diseases and from healthy individuals. The results clearly show that bacteria release histamine by immunological and non-immunological mechanisms and that endotoxins enhance mediator release caused by allergens in allergic patients or by bacteria in persons sensitized to these organisms. Furthermore, a great increase is obtained in mediator release by the combination of immunological and non-immunological mechanisms.

Adult↗
PubMed1986

Late-onset rubella syndrome: coexistence of immune complex disease and defective cytotoxic effector cell function.

We studied a classical case of late-onset rubella syndrome characterized by multi-organ disease and persistence of live rubella virus in spite of high titres of specific antirubella antibodies and presence of large amounts of circulating immune complexes. When first studied at the age of 5 months there was a low proportion of T8+ lymphocytes. Functional studies revealed decreased activity of K and NK cells as well as alloreactive direct cytotoxic cells (CTL). Removal of cell-bound immunoglobulin and immune complexes tended to improve K and NK cell function in vitro. Plasma exchange transfusions carried out at 9 months of age resulted in clinical improvement. Normalization of cytotoxic effector cell functions and cessation of viremia accompanied recovery from active disease. The results indicate that defective cytotoxic effector cell function is the primary cause for the defective virus elimination in this syndrome.

Antibodies, Viral↗
PubMed1986

The alternative complement pathway in chickens. Purification of factor B and production of a monospecific antibody against it.

Restoring the haemolytic activity of heat-treated chicken serum was used to monitor an initial purification of chicken complement component factor B of the alternative complement pathway. The partially purified factor B was used to prepare a monospecific rabbit antiserum against factor B, and this antiserum was now used to monitor and establish a purification scheme for chicken factor B which could be used for large-scale purifications. The final purification involved precipitation with polyethyleneglycol, ion exchange chromatography on CM 52-cellulose, gel-filtration on Sephadex G 200, elution from a Con A-Sepharose column, and finally ion exchange chromatography on a DE 52-cellulose column. 2.8 mg of factor B was purified from 100 ml of chicken plasma with a yield of 28%. Purity was high as judged from crossed immunoelectrophoresis, SDS-PAGE, and from immunizations of rabbits with the factor B preparation. The purification gave preliminary indications that chicken factor B is a glycoprotein with beta-mobility and with a molecular weight around 95 Kd.

Animals↗
PubMed1985

A simple immunoblotting method after separation of proteins in agarose gel.

A simple and sensitive method for immunoblotting of proteins after separation in agarose gels is described. It involves transfer of proteins onto nitrocellulose paper simply by diffusion through pressure, a transfer which only takes about 10 min. By this method we have demonstrated the existence of multiple molecular forms of the complement factors C3 and factor B in serum from 2 species, man and chicken, after electrophoretic separation in agarose. We have also demonstrated the usefulness of the method for determining the isoelectric point of proteins after isoelectric focusing in agarose.

Animals↗
PubMed1985

The biophysical properties of spines as a basis for their electrical function: a comment on Kawato & Tsukahara (1983).

In a theoretical study of the passive cable properties of dendritic spines Kawato & Tsukahara (1983) claim to have proved that "the dendritic spine has no significant electrical function" (from their discussion). However, Kawato & Tsukahara restrict their analysis to current inputs to spines. Since the dimensions of spines are very small, their input resistance is expected to be very large and the synaptic input to spines has to be modeled as conductance change. Under this assumption, spines show interesting (non-linear) electrical properties: i) the somatic potential induced by an excitatory synapse on a spine may depend strongly on the shape of the spine and ii) the effect of inhibition might be confined to the spine.

Dendrites↗