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Biomedical subjects

C Koch

Publications and source records attributed to C Koch.

At least 433 records · Page 24Linked to original sources
PubMed1983

Intrinsic asthma and bacterial histamine release via lectin effect.

Bacteria-induced histamine release from basophil leukocytes was observed in vitro in both children with intrinsic asthma (IA) as well as in normal individuals. In vivo the release is suggested to take place only in the lung of IA patients, where a defective pulmonary barrier would permit the bacteria to enter, but not in healthy individuals. The study indicates that two different mechanisms of bacterial histamine release might exist, an IgE-mediated reaction and a non-immunological mechanism consisting of a direct interaction with the basophil cell surface. The non-allergic mechanism might depend on a lectin effect where bacterial surface lectins interact with the basophil cell surface leading to release of histamine. Inhibition studies with carbohydrates suggest a multi-lectin reaction in the bacterial histamine release involving several types of lectins on the bacterial membrane reacting with different carbohydrate moieties on the cell surface of basophil leukocytes.

Asthma↗
PubMed1983

Non-respiratory haemolymph proteins in the vineyard snail Helix pomatia. Changes after phagocytosis in vivo.

Haemolymph proteins from the vineyard snail Helix pomatia were studied by chromatographic and immune-electrophoretic techniques with the dual purpose of characterizing the normal composition of haemolymph and to look for possible opsonins. The oxygen-carrying proteins, alpha- and beta-haemocyanin, were by far the most abundant proteins, but at least three non-respiratory proteins could be demonstrated. We found consistent changes in the appearance of the immunoprecipitation pattern of these non-respiratory proteins after the injection of particulate foreign matter into the snail's circulation, and we suggest that they may be opsonins. We also found a haemagglutinin in haemolymph. It was present in very low concentration and was similar to, but not identical with the haemagglutinin which is present in the albumin gland.

Animals↗
PubMed1983

Nonlinear interactions in a dendritic tree: localization, timing, and role in information processing.

In a passive dendritic tree, inhibitory synaptic inputs activating ionic conductances with an equilibrium potential near the resting potential can effectively veto excitatory inputs. Analog interactions of this type can be very powerful if the inputs are appropriately timed and occur at certain locations. We examine with computer simulations the precise conditions required for strong and specific interactions in the case of a delta-like ganglion cell of the cat retina. We find some critical conditions to be that (i) the peak inhibitory conductance changes must be sufficiently large (i.e., approximately equal to 50 nS or more), (ii) inhibition must be on the direct path from the location of excitation to the soma, and (iii) the time course of excitation and inhibition must substantially overlap. Analog AND-NOT operations realized by satisfying these conditions may underlie direction selectivity in ganglion cells.

Action Potentials↗
PubMed1983

Ceftazidime treatment of chronic Pseudomonas aeruginosa respiratory tract infection in cystic fibrosis.

Two open randomized cross-over studies were undertaken comparing ceftazidime to tobramycin and ceftazidime to tobramycin plus carbenicillin in 13 and 15 cystic fibrosis (CF) patients, respectively, with chronic bronchopulmonary Pseudomonas aeruginosa infection. The difference in lung function improvement was statistically better in terms of FEV1 and FVC for the ceftazidime group in the study versus tobramycin plus carbenicillin. Patients receiving ceftazidime showed a tendency for a greater long-term benefit in lung function as measured at 1 and 2 months after treatment than patients receiving the other antibiotics. Development of resistance against both ceftazidime and carbenicillin was seen regularly and was not prevented by combination therapy with tobramycin. No resistance developed when tobramycin was used as monotherapy. Serum concentration curves for ceftazidime fitted a two compartment first order open model in CF patients and showed a distribution volume of 40% of the body weight and a final serum half-life of 1.8 h. One case of Type III hypersensitivity reaction was seen during ceftazidime treatment. Ceftazidime seems to be an effective and safe antibiotic in the treatment of Ps. aeruginosa bronchopulmonary infection in CF patients, although these bacteria could not be eradicated.

Adolescent↗
PubMed1983

Origin of peripheral blood macrophages in bursa-cell-reconstituted chickens. Further evidence of MHC-restricted interactions between T and B lymphocytes.

MHC class-I antigens on peripheral blood macrophages and bursa cells were analysed after adoptive bursa cell transfer to cyclophosphamide-treated immunodeficient chickens. We studied the expression of B-F locus-encoded antigens (B-F is homologous to mouse H-2K, D) on macrophages and B cells and found that macrophage B-F antigens are of host origin, whereas bursa cells express only donor-type B-F antigens. Both syngeneic and allogeneic bursa cells restored IgM antibody production to a T-cell-independent antigen, Brucella, but only syngeneic bursa cells could restore the IgG antibody response to a thymus-dependent antigen, sheep erythrocytes. The results indicate that B-cell maturation and macrophage-B-cell interaction are not MHC-restricted but that a restriction exists in T-cell-B-cell collaboration.

Animals↗
PubMed1983

New recombinants within the MHC (B-complex) of the chicken.

In a search for genetic recombinations within the major histocompatibility complex (MHC) of the chicken, the B-complex, the offspring from matings between heterozygous B15/B21 and B4/B6 animals were analysed by red cell agglutination. Among the progeny, 8,912 informative typings were performed. Four recombinants were found, all separating the B-complex loci B-F and B-G (B-F codes for Class I antigens, B-G codes for an antigen of which there is no known homologue in mammals). B-L (Class II antigen) always followed B-F. Stimulation in graft versus host reactions and in mixed lymphocyte cultures followed B-F/B-L. The mapping distance between the two loci B-F and B-G is in the range of 0.04 centimorgan. The lack of recombinants separating individual B-F loci in this study and in the studies of others might indicate that chicken MHC is less complex than those of mammalian species, but alternative explanations are also possible. So far no serologically defined recombinant separating Class I (B-F) and Class II (B-L) loci has been found.

Absorption↗
PubMed1983

Treatment of chronic pseudomonas aeruginosa infection in cystic fibrosis patients with ceftazidime and tobramycin.

50% inhibitory concentration (IC50) and minimum inhibitory concentration (MIC) of ceftazidime, cefsulodin, cefotaxime, moxalactam, azlocillin, carbenicillin, netilmicin and tobramycin against 90 strains of Pseudomonas aeruginosa isolated from cystic fibrosis (CF) patients were determined by means of the agar plate dilution method. Ceftazidime was most active of the antibiotics in vitro; the geometric mean of IC50 was 0.2 and of MIC 0.4 micrograms/ml. 11 CF patients suffering from P. aeruginosa infection were treated with 14 day courses of ceftazidime (100 mg/kg/24 h) and tobramycin (10 mg/kg/24 h). P. aeruginosa was only temporarily eradicated in one of the patients, but a significant improvement of respiratory function and a significant fall in white blood cell count was recorded in the patients during chemotherapy. There was no development of resistant strains against ceftazidime during treatment and no side-effects were observed. Ceftazidime is a promising new antimicrobial agent with high in vitro activity which deserves further in vivo evaluation in CF patients.

Adolescent↗
PubMed1983

Characterization of two strains of selectively bred guinea-pigs. 2. Differences in immune response to synthetic polypeptides.

Two strains of guinea-pigs selectively bred for either high (IMM/S) or low (IMM/R) responsiveness to ovalbumin-induced respiratory anaphylaxis were examined for their immune response to a copolymer of L-glutamic acid and L-alanine (GA), a copolymer of L-glutamic acid and L-tyrosine (GT), and to a dinitro-phenyl derivative of a homopolymer of L-lysine (DNP-PLL). Considerable differences between the strains in development of cellular hypersensitivity and in the production of antibodies were observed. Guinea-pigs from IMM/S were all responders to GA and DNP-PLL and non-responders to GT, while guinea-pigs from two of three lines from IMM/R were responders to GT and non-responders to GA and DNP-PLL. The third IMM/R line showed an immune response pattern similar to guinea-pigs of strain IMM/S. Preliminary breeding studies confirmed that the immune response to these three antigens is under the control of dominant autosomal genes, since (IMM/S x IMM/R) F1 animals responded to all three antigens. It is concluded that these three antigens may serve as immune response markers in genetic studies of the differences between guinea-pigs from IMM/S and IMM/R in their ability to develop respiratory anaphylaxis.

Alanine↗
PubMed1982

The MHC haplotypes of the chicken.

The major histocompatibility complex (MHC) of Gallus gallus is the B complex of which three classes of cell-membrane antigens have been clearly defined by serological, histogenetic, and biochemical methods. Two of these classes are homologous to classes I and II of mammals (B-F and B-L, respectively), while the third (B-G) is a differentiation antigen of the erythroid cell-line; the mammalian homologue of this class is still undefined. The B haplotypes comprise at least one gene of each class that displays linkage disequilibrium of a remarkable strength. The present work is the first systematic comparison by serological and histogenetic methods of the allelic products (allomorphs) of 15 haplotypes, including all of the 11 that were accepted as "standard" B haplotypes at the recent international Workshop on the chicken MHC in Innsbruck, Austria. The analysis has revealed many similarities, but only four pairs of probable identities: G2 and G12, F4 and F13, L4 and L13, L12 and L19. It appears therefore that the B-G locus is comparable in its degree of polymorphism to the class I (B-F) locus. The "standard" haplotypes are almost all of White Leghorn derivation, and preliminary typings of other breeds of chickens, and of wild chickens, indicate the existence of a much wider spectrum of allomorphs.

Alleles↗
PubMed1982

Complement mediated lysis in chickens.

Rat erythrocytes, when either injected i.v. into chickens, or incubated in vitro with chicken serum, will be lysed within minutes. This lysis is complement dependent but does not involve specific antibodies since Ig-free bursectomized chickens behave in exactly the same way as normal chickens with high levels of haemagglutinating antibodies. The lysis is mediated by activation of complement component C3 via the alternative complement pathway and various observations lead us to doubt the functional existence in this lytic reaction of the classical complement pathway.

Animals↗