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Biomedical subjects

M Hartmann

Publications and source records attributed to M Hartmann.

At least 361 records · Page 20Linked to original sources
PubMed1986

The influence of hemorrhagic hypotension on spinal cord tissue oxygen tension.

In order to investigate the spinal cord surface PO2 (sPO2) reaction to hypovolemic hypotension, nine female pigs (25 kg bw) were premedicated, anesthetized, intubated and artificially ventilated with N2O:O2 = 3:1. Following laminectomy from L3 to L5, sPO2 was measured on the dorsal side of the exposed spinal cord using six gold cathodes (luminal diameter 15 microns) while MAP (mean +/- SD) was lowered in steps of about 10 Torr by bleeding into a reservoir from 69.3 +/- 10.1 Torr to extreme low values of 13.3 +/- 3.1 Torr. Only a slight decrease of lumbar sPO2 (mean +/- SD) from 33.5 +/- 7.2 Torr to 27.6 +/- 4.8 Torr was evaluated from the data in response to MAP reduction to 50.2 +/- 3.5 Torr. Below that value, a marked proportional decrease of sPO2 and MAP was observed (0.65 Torr/Torr) corresponding to pressure passive flow behavior of the Hagen Poisseuille Law ("loss of autoregulation"). Four to five minutes after start of reinfusion both sPO2 and MAP showed an overshoot with maximum values of 54.0 +/- 11.1 Torr resp. 102.6 +/- 18 Torr. Initial values were approximated about 15 min. later. Histograms plotted from the individual sPO2 values of all pigs and of all the different experimental stages showed signs of severe hypoxia only if MAP was reduced below about 30 Torr. In general, this situation was reversible within reinfusion, only one of the nine pigs did not tolerate hemorrhagic hypoxia induced by MAP reduction to less than 30 Torr for at least 5-10 min. Nevertheless, the experiments showed a considerable circulatory stability in the investigated pigs.

Animals↗
PubMed1986

Colicinogeny in chronic inflammatory bowel disease.

There are several indirect arguments for a possible role of colicins in chronic inflammatory bowel disease (IBD). Colicinogeny was therefore investigated in 54 patients with ulcerative colitis, 39 patients with Crohn's disease, and 160 clinically healthy controls. No significant difference was found among the examined groups. The leukocyte migration inhibition test (with colicins as antigens) was performed to estimate cellular hypersensitivity to colicins. Migration indices not exceeding the normal range in controls contrasted with abnormal values found in 36% of ulcerative colitis and 80% of Crohn's disease patients. The results are believed to be proof of cellular hypersensitivity of IBD patients to colicins of their own Escherichia coli strains. The importance of this finding must be further clarified.

Adult↗
PubMed1986

[Realtime sonography of intrascrotal space-occupying lesions].

In 848 examinations of the testes in 317 patients, including 253 follow-up and/or multiple follow-up examinations and 36 unilateral testicle examinations (e.g., orchidectomy, aplasia or nondescent) it was shown that sonography is a diagnostic method which is on the one hand capable of clearly differentiating cystic from solid space-occupying processes, and on the other hand also offers certain possibilities for evaluating the status of solid findings. Histologic identification of malignant tumors was only achieved with teratomas. The differential diagnostic problem was in differentiating scrotal tumors from focal orchitis, chronic epididymitis, testicular torsion and contusion, and in differentiation between paratesticular neoplasms and epididymitides. The testicular findings included testicular neoplasms, cicatrization and cysts of the tunic, sequelae of trauma, orchitis, cryptorchism, hypoplasia, aplasia, and testicular cysts. Paratesticular findings included hydroceles, spermatoceles, varicoceles, paratesticular neoplasms, epididymitides, paratesticular scars, and thickening of the testicular coat.

Diagnosis, Differential↗
PubMed1986

[Structure-release relationship of physical polymer/drug combinations. 2. Diffusion of 3-methylpyrazole through a synthetic polymer matrix].

The diffusion of 3-methylpyrazole through a synthetic polymer matrix and the effect of the solubility of the bioactive agent in polymers on the release behaviour of polymer combinations were studied. With increasing hydrophilicity of the polymer both the diffusion and the diffusion coefficient of 3-methylpyrazole increased and the solubility of the agent in the polymer decreased. The hydrophilicity of various polymers is discussed on the basis of a parameter determined by turbidimetric titrations.

Chemical Phenomena↗
PubMed1985

Lumbar and thoracic spinal cord oxygen tension during aortic cross-clamping.

In order to investigate the changes in tissue oxygen and the efficiency of the collateral circulation in the different regions of the spinal cord (SC) during aortic occlusion, surface PO2 (sPO2) was measured on the exposed SC in the pig in the lumbar (L3-5) as well as in the thoracic (Th6-8) parts before, during and after a 45 minute occlusion. The pigs were divided into two groups: group IA: cross-clamping of the aorta immediately below the left subclavian artery; group II: occlusion of the aorta immediately above the arteria radicularis magna anterior (ARMA). In response to occlusion, the sPO2 distal to the occlusion always decreased significantly (group IA: mean lumbar sPO2 from 42.3 mm Hg to 3.2 mm Hg, mean thoracic sPO2 from 34.9 mm Hg to 3.9 mm Hg; group II: mean lumbar sPO2 from 28.0 mm Hg to 7.9 mm Hg). Mean thoracic sPO2 in group II remained constant. No statistically significant differences between the distal regions could be established. The collateral circulation in the thoracic as well as in the lumbar region was insufficient at least during occlusion.

Animals↗
PubMed1985

Interaction of histone H1 from sea urchin sperm with superhelical and relaxed DNA.

Complexes of histone H1 from sea urchin sperm (H1S) and calf thymus (H1T) with superhelical DNA I and relaxed circular DNA II have been analyzed by analytical sedimentation. Similar to H1T, the highly basic and relatively arginine-rich histone H1S preferentially interacts with DNA I compared to DNA II under competition conditions. However, H1S induces a stronger aggregation of both forms of DNA than H1T. Below 0.05 M NaCl, the soluble complexes formed by both histones have similar properties, but aggregation proceeds in a different manner: H1S induces a stronger aggregation of DNA II as compared to DNA I, whereas H1T fails to aggregate DNA I. The results are explained on the basis of differences in amino acid sequence and structure of the two histones and related to the special chromatin condensing ability of histone H1S.

Animals↗
PubMed1985

Direct measurements of oxygen tension on the spinal cord surface of pigs after occlusion of the descending aorta.

Spinal cord injury is the most dreaded complication of operative procedures on the descending aorta. Our previous experimental study on pigs indicated that an increase in the cerebrospinal fluid pressure after aortic cross-clamping did not influence the occurrence of spinal cord injury. We therefore concluded that the cause of spinal cord injury after aortic cross-clamping is due to primary oxygen deficiency in the spinal cord distal to the occlusion site, especially in the area supplied by the artery of Adamkiewicz. The aim of the present study is to examine the primary ischemic cause of spinal cord injury after aortic cross-clamping by directly measuring the oxygen tension on the spinal cord surface in pigs. During the occlusion phase, oxygen tension decreased significantly distal to the clamping site and especially in the areas supplied by the artery of Adamkiewicz both after occlusion of the high thoracic (Group I) and the lumbar aorta (Group II). The marked decrease in oxygen tension proves that hypoxia is the primary reason for spinal cord injury. The presence of a "steal phenomenon" should be discussed.

Animals↗
PubMed1985

[Structure-release relationships of active polymeric drug combinations. 1. The influence of polymer structure on the diffusion of 3-methylpyrazole from monolithic systems].

The release of 3-methylpyrazole from monolithic polymer films into aqueous media has been studied. The diffusion of the active agent decreased with increasing of the content of acetate groups in reacetylated poly(vinyl alcohols) and with increasing of the ester lengths in copolymers of maleic esters, respectively. The release rate of active ingredient is dependent on the hydrophilicity of the polymer films. Contrary to the glass transition temperature the hydrophilicity of polymers expressed the interaction between polymer chains and water in a direct way. The hydrophilicity of copolymers of maleic esters correlated with the turbidimetric point, which can be determined by acidimetric titrations. The influences of interactions between polymers and the active agents on their diffusion in the polymers were also discussed.

Chemical Phenomena↗