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Biomedical subjects

J Meissner

Publications and source records attributed to J Meissner.

At least 55 records · Page 3Linked to original sources
PubMed1976

[Release of 14c-chloramphenicol in the rabbit femur implanted with polymethylmetacrylate (author's transl)].

In vitro studies and animal experiments were started for the purpose of following the migration of chloramphenicol marked with 14C from polymerised polymethylmetacrylate cylinders. Test-cylinders were submerged in a physiological saline solution and the 14C concentration followed over a period of 34 days. Two series were started with the cylinders being submerged at intervals of 5 and 40 min after the start of polymerisation. These in vitro studies showed that initially the migration of active substances marked with 14C from the plastic cylinders was extremely high but remained then constant over the whole test period. Over a period of at least 20 days a higher 14C migration was evident in those cylinders submerged in the elution 5 min after the start of polymerisation. In our in vivo studies we implanted test-cylinders into the femur of rabbits. The migration of active substances marked with 14C resulted in 14C-concentrations being present in the surrounding tissues. During the phase of exudation, depending on the operative process, the concentration increased and reached values that remained constant during the phase of recanalisation of the surrounding tissues over a period of up to 6 weeks. Thereafter the concentration of active substances fell. The max. concentration rates of active substances within the boundary layer were between 15 and 20 mug/g humidity weight. After 8 weeks we found concentration rates of approx. 1 mug/g humidity weight. On examining the 14C distribution within the implanted plastic cylinders we observed that in the course of time the boundary layer increased in thickness and a concentration gradient towards the centre had developed. The spread of diffusion gradually seized the deeper layers so that a long-lasting presence of active substances may be expected.

Acrylic Resins↗
PubMed1976

Distribution and diaplacental passage of infused 3H-fenoterol hydrobromide (partusisten) in the gravid rabbit.

Tritium-labelled fenoterol hydrobromide was infused into an ear-vein of pregnant rabbits over a period of 4 hours. Two doses were used. The tritum concentrations in the blood of the dams and the amniotic fluid were determined from samples obtained during infusion and up to 11 hours after completion of infusion. The tritium concentrations were also determined in selected organ samples from dams and fetuses, taken immediately and 5 and 11 hours after infusion. Within 1.5 hours after commencement of infusion, the tritium activity in the whole blood of the dams reached a plateau on a level corresponding to the dose administered. Immediately after completion of infusion, the level of radioactivity fell rapidly. The tritium concentration in the amniotic fluid began to rise far more slowly after a time lag, so that approximately 2 hours after completion of infusion, the concentrations in maternal whole blood and amniotic fluid were equal. As the amniotic fluid level fell at a slower rate than the maternal whole blood level, the former somewhat exceeded the latter at this advanced stage of the study. The tritium distribution patterns of the dams indicate rapid elimination via kidneys and intestine. The tritium concentration in all the tissue fell rapidly after completion of infusion. The lung and uterus have a slightly greater affinity. The tritium concentrations in the fetal organs remained below those in the organs of the dams for the whole duration of the study. The highest radioactive concentration in the fetuses was found in the urine. Further observation of the rapid conversion of fenoterol hydrobromide into conjugates leads us to expect only minimal amounts of active substance to be found in the fetuses after infusion.

Amniotic Fluid↗
PubMed1976

[Various physical and chemical properties of the 73s unit of the foot-and-mouth disease virus].

At all 3 studied FMD-viruses typs O2, A5 and C we could show the 73S unit in the analytical ultracentrifuge and in the electron microscope. 73S unit is found in the normal cycle of purification of virus and by density gradient centrifugation separated and purified. In CsCl pH 7.6 its density is 1.308 +/- 0,005 g/ml. Its sedimentation coefficient has a value of 72.7 +/- 1,5S. In electron microscope it show itself as a empty virus capsid. Its diameter is in partial purified preparations with 25 +/- 1 nm the same as of the virion. Its wall diameter is 2 to 3 nm. Further purification induced defiguration of particles and increase of its diameter. 73S unit dissociates in 19S and 12S units and shows a typical protein-UV-absorption spectrum with a maximum at 276 to 278 nm and a minimum at 250 nm. Emax/Emin is 2.3. Extinction coefficient E276nm is 1,4 mg/cm2. By sucrose density gradient centrifugation and titration of fractions in the complement fixation test it was detected, that croude virus solution contained already the 73S unit.

Antigens, Viral↗
PubMed1975

[Distribution of 14C-Diazepam (Valium) in pregnant and lactating rabbits].

14C-labelled Diazepam is applied i.v. in a single dose to pregnant rabbits and in three repeated doses to lactating rabbits. The distribution patterns of the radioactivity in the mother animal and in the fetus resp. in the sucklings are investigated at different intervals post inj. within a range of 10 to 120 minutes for the pregnant and at 8 hours after last injection for the lactating animals. With regard to its metabolic properties it is still admissible to identify the recorded radioactivity with the intact pharmaceutical to large extent for the intervals used in the experiments. The compound is distributed rapidly within the maternal organism and is excreted preferentially by the liver. Compared to blood level a considerable 14C-enrichment is obvious in the brain during the total time of investigation, which seem to be of special interest for the clinical use of the diazepam. An organotropism to the ovary is indicated by the patterns of radioactivity. A rapid diaplacental passage can also be shown, but the 14C-concentrations in blood and organ tissues of the fetus are generally found to be lower than those of the maternal organ tissues. Thus, the 14C-concentration in the fetal brain is equal to 1/3 of that of the maternal brain. Due to the mammoglandular passage the 14C-concentrations in the sucklings are reaching a maximum of one half of the values in the maternal organs.

Animals↗