Biomedical subjects
Publications and source records attributed to M Becker.
Blood pictures, serumelectrolytes, acid-base- and bloodgas-values of the arterial blood were determined from two juvenile and one adulte collectives of minipigs (Gottingen strain), which were kept under SPF-conditions. The results were compared with the corresponding values of human blood and should be regarded as base- or orienting values for further investigations.
Sera from 41 children suffering with histologically proven coeliac disease and from 40 healthy control children were investigated for the presence of antireticulin antibodies and precipitating antibodies to a watery extract of wheat flour and to cow's milk. Antireticulin antibodies were demonstrated by means of indirect immunofluorescence using sections of fresh rat kidney as substrat. For the detection of precipitating antibodies a combination of electrophoresis and immunodiffusion was used. Serum antireticulin antibodies were found in 11/13 children (85%) with active coeliac disease, in 7/17 children (41%) with clinically and biochemically silent coeliac relapse and in 0/16 children with treated coeliac disease. Serum precipitating antibodies to wheat flour and cow's milk were found respectively in 3/13 children (23%) and 2/13 children (15%) with active coeliac disease and in 1/16 children (6%) with treated coeliac disease. Precipitating antibodies could not be detected in the sera of 17 patients with silent relapse of coeliac disease. In the sera of 40 controls neither antireticulin nor precipitating antibodies were detectable. The presence of antireticulin antibodies in serum did not correspond to the presence of serum precipitins to wheat flour and cow's milk. The significance of serum antireticulin antibodies for screening investigations and for follow-up studies is discussed.
Mice of 10 inbred strains were immunized with a protein conjugate of a hapten of p-azobenzenearsonate coupled to the carbon atom 5 of hydroxphenylacetic acid (ABA-HOP), and anti-ABA-HOP titers were determined by the haptenated phage inactivation. Mean titers of C57BL/6 and BALB/c mice were significantly lower than those of A/J and CBA strains. The titers were under a polygenic control and did not correlate with allotypes in backcross mice. Fine specificity of the anti-ABA-HOP was characterized by inhibiting the haptenated phage inactivation reaction with five chemically related compounds including ABA-HOP (Fig. 1). This antibody was genetically more polymorphic than any other antibody studied. Three distinct idiotypes could be demonstrated and the number is probably greater. The idiotypes of the A/J and C57BL/6 were inherited as allotype-linked dominant Mendelian traits, the former in two and the latter in three different backcrosses. Condominance of the two alleles was shown since approximately equal amounts of the two idiotypes were produced by the population of heterozygous mice. There were many individual heterozygotes, however, in which only one parental idiotype could be detected. In other individuals of the same genotype the other parental idiotype was predominant. In many mice a mixture of the two idiotypes was indicated by doubly sigmoid inhibition curves. The causes for the variation in the expression of the two alleles in genotypically identical mice is discussed.
It is shown by means of circular dichroism studies of variously condensed forms of DNA that the specific supramolecular structure of DNA determines the type of CD spectra. DNA, condensed (crystallized) slowly in the presence of cetyltrimethyl ammonium bromide yields a spectrum very similar to that of DNA in solution in the B-form. The condensates appear in the phase-contrast microscope as spherulitic crystallites. Rapidly condensed DNA in the presence of cetyltrimethyl ammonium bromide shows a spectrum of the psi-type with large negative ellipticites. The influence of condensation velocity upon the supramolecular structure of DNA gives evidence that the various condensation forms of DNA are not thermodynamical equilibrium conformations.
CD spectra of DNA monocrystals are extremely different from spectra of psi-DNA or DNA-histone H1 or DNA-polylysine complexes. They are discussed to be dependent on the supramolecular organization of DNA in the condensed form, and they are not in contradiction to the previously proposed seven folding model of DNA in chromatin. Conclusions are drawn with regard to the interpretation of chromatin CD spectra.
We investigated lactate dehydrogenase activity in serum and plasma because of the conflicting data found in the literature. We assayed serum, platelet-rich, and platelet-poor plasma by two colorimetric endpoint methods and by an ultraviolet kinetic procedure. Platelet-poor plasma and serum had essentially the same activities by all three methods, whereas the activity in platelet-rich plasma plasma averaged fourfold that in platelet-poor plasma or serum when the assay was performed under conditions that result in lysis of platelets and release of their lactate dehydrogenase. When measurements were performed in platelet-rich plasma under conditions that prevented lysis of platelets, all three types of specimens gave the same results. This occurred when the osmolality of the reaction mixture was about 240 mOsm/kg of water. At an osmolality of about 120 mOsm, the activity of platelet-rich plasma was substantially lower than that of platelet-poor plasma or serum. If plasma must be used, the sample must first be centrifuged (3000 X g, 15 min) to provide a platelet-free plasma.
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The miniature swine is steadily gaining prominence as a laboratory animal. This paper attempts to survey the existing literature concerning the Göttinger Minipig and to give some information about breeding, growth-rate and handling. Further studies dealing with the circulation (ECG, blood pressure and heart-rate) of conscious minipigs are reported. In this regard, the Göttinger Minipig is shown, to display a more favorable ratio between diastole and systole than normal swine.
Pairs of rats were placed in an apparatus where their sole food source hung over an electrified grid. The current was shut off only while one rat remained on a platform out of reach of the food, thus allowing his partner to eat. Mastery of the process of taking turns at eating required about 10 daily sessions. Injection of imipramine or chlordiazepoxide a few minutes after each feeding session prevented the development of this cooperative behavior. Drug injection 3 hrs after each session had no effect. Suppression of REM sleep during the first 3 hrs after training was considered the most likely mechanism of the drug-induced impairment.
Nanogram quantities of alpha-fetoprotein (AFP), a tumor associated fetal protein, were found in the serum of normal adult rabbits by radioimmunoassay. This AFP was isolated and shown to be immunologically identical to fetal AFP by immunodiffusion. Immunizations of rabbits with unmodified to desialylated AFP in complete Freund's adjuvant did not cause antibody formation, indicating the existence of tolerance against homologous AFP. The tolerance could be terminated by immunizing with hapten-coupled AFP, which resulted in production of rabbit antibodies reacting with unmodified rabbit AFP.
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