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Biomedical subjects

B Schmidt

Publications and source records attributed to B Schmidt.

At least 469 records · Page 26Linked to original sources
PubMed1986

Fusion of renal epithelial cells: a model for studying cellular mechanisms of ion transport.

The investigation of epithelial ion transport at the cellular level by means of electrophysiological techniques is hampered by the small size of epithelial cells. Moreover, interpretation of experiments is complex due to poorly defined and highly variable paracellular leaks (shunt pathways). In search of a new experimental approach we developed a technique to isolate renal epithelial cells (diameter approximately equal to 10 micron) from diluting segments of the frog kidney and to fuse them to "giant" cells (diameter approximately equal to 100 micron). These cells generate membrane potentials of -54.1 +/- 1.6 mV (mean +/- SEM; n = 40). They are sensitive to the diuretic drugs furosemide and amiloride and to the K+- and Cl- -permeability blockers Ba2+ and anthracene-9-carboxylic acid. The experiments demonstrate membrane potential measurements in cells isolated from renal epithelium and fused to giant cells. The cells retain their specific membrane properties and could serve as a valuable experimental model in epithelial research.

Amiloride↗
PubMed1986

Determination of plasma C3a des Arg levels after blood contact with foreign surfaces.

The products of complement activation, including C3a, C4a, C5a, and their des Arg derivatives, have been used by many investigators as indicators of blood or foreign surface bioincompatibility, e.g., during hemodialysis. One problem encountered is that after extracorporeal circulation over some dialysis membranes very high C3a levels (5,000-10,000 ng/ml) are generated. To the authors' knowledge the only presently available C3a des Arg RIA kit is provided by Upjohn Diagnostics (Kalamazoo, MI, U.S.A.), which covers an assay standard range of 20-500 ng/ml. Since Upjohn's assay procedure manual does not contain a recommended dilution technique the authors undertook a study to determine the best method. The diluents tested include physiologic saline, normal plasma, phosphate-buffered saline-gelatin, and the Upjohn precipitating agent provided in their kit. The results show that only dilution by normal plasma gave reliable results. The use of the other three diluents resulted in an overestimation of C3a levels. Therefore it is important to know the dilution technique used when comparing the results of membrane C3a generating ability presented by different authors. Furthermore, comparison of different membranes where plasma samples in some cases do not require dilution (e.g., polyacrylonitrile membranes) with those requiring dilution (e.g., regenerated cellulose membranes) will lead to distorted results if an accurate technique is not used.

Biocompatible Materials↗
PubMed1986

Protoplast transformation in coryneform bacteria and introduction of an alpha-amylase gene from Bacillus amyloliquefaciens into Brevibacterium lactofermentum.

The goal of this study was to investigate the likelihood of developing useful transformation systems for coryneform bacteria. Two species of coryneform bacteria, Brevibacterium lactofermentum and Corynebacterium lilium, were transformed with chimeras constructed from pUB110 and a cryptic coryneform plasmid (pGX1901). C. lilium protoplasts were also efficiently transfected with phage CS1 DNA. High transformation and transfection frequencies were obtained after only 2 min of lysozyme treatment of lysozyme-sensitive mutants. A series of experiments was also conducted to determine whether DNA from other species of important industrial microbes from the genus Bacillus could be expressed in coryneform bacteria. Evidence of restriction of Bacillus subtilis DNA by B. lactofermentum was observed but could be overcome. A Bacillus amyloliquefaciens alpha-amylase gene (amyEBamP) was subcloned onto a plasmid able to replicate in B. lactofermentum. B. lactofermentum transformants for this plasmid expressed amylase activity and produced material cross-reactive to amylase antibody.

Bacillus↗
PubMed1986

[Computed tomographic localization of the uterus for optimization of primary combined radiotherapy of inoperable cervix cancer].

The authors present the technique of CT reconstruction of the shape of the uterus in topograms of the pelvic region. The treatment scheme of combined endocavitary and percutaneous radiotherapy of uterine cervix carcinomas can be improved by means of the described method. The reliability of this method is compared to that of radiotherapy planning based on measuring radiography. Modifications of the position of the uterus obtained by endocavitary inserts proved to be relevant if the endocavitary regions exposed to high doses are left out from percutaneous therapy.

Brachytherapy↗
PubMed1986

[Subjective quality of life of surgically treated glioma patients undergoing polychemotherapy].

25 patients with glioma were questioned as to how they apprehended and appreciated their state of health and their psychosocial situation 1 1/2 years (s = 4 months) after the start of their postoperative polychemotherapy. In their opinion, their health was relatively good, that is, they claimed to suffer little pain, few complaints, little feeling of inadequacy, few fears for the future. They regarded the mode of treatment as being somewhat more inconvenient. Such an unexpectedly positive response, in view of the poor prospect, raises the question as to its provenance. A significant cause is seen in the organic psycho-syndrome, and its significance is made the subject of the concluding discussion, with reference to adaptation mechanisms and specifics of the illness.

Adult↗
PubMed1986

Biocompatibility and clinical performance of a new modified cellulose membrane.

A new modified cellulose dialysis membrane (MC, 1.2 m2) in which less than 5% of cellulosic OH-groups are substituted by tertiary amino groups was tested in a 6-week clinical trial for biocompatibility and clinical performance and compared to both regenerated cellulose (RC, 1.2 m2) and cellulose acetate (CA, 1.0 m2). Ten patients on maintenance hemodialysis took part in the study; all hollow fiber modules were equally well tolerated and no adverse reactions were observed. Using MC/RC/CA, mean clearances after 15 min of hemodialysis (HD) amounted to 162/169/150 ml/min for urea, to 143/143/124 ml/min for creatinine, and to 104/107/84 ml/min for phosphate (QB = 200 ml/min, QD = 500 ml/min, UFR = 0). Mean drop of systolic blood pressure was 6/10/8 mmHg and mean decrease of heart rate averaged 3/3/3 beats per minute, respectively, during the first hour of HD as compared to starting conditions. Residual blood volume in the modules after HD was low and heparin consumption identical for all 3 membranes (34 IU/kg X h). Mean peak C3a generation for MC/RC/CA amounted to 1312/3486/3099 ng/ml, respectively; leucocyte and platelet counts dropped to a minimum of 67/24/47% and 81/86/91%, respectively during the first hour of HD as compared to initial values. Elastase release from PMNL and platelet factor 4 from platelets showed no significant differences between the membranes. In conclusion, the new MC membrane showed a significantly better biocompatibility and equally good clinical performance as compared to RC and CA.

Biocompatible Materials↗
PubMed1985

Secretion of phospholipase A1 by bone marrow-derived macrophages.

Bone marrow-derived macrophages contain phospholipase activity of the A1 and A2 types, active at acid or neutral pH and with different specificities for the fatty acid to be liberated. In contrast to this variety, only one single phospholipase could be detected in extracellular fluids of these cells. Surprisingly, this phospholipase was of the A1 type and active at about pH 8. It exhibited a restricted substrate specificity in that, of the various substrates tested, only phosphatidylcholine containing palmitic acid in position 2 was degraded. This total restriction was not detected with phosphatidylethanolamine substrates. In addition to phospholipase A1, extracellular fluids exhibited lipase activity. A modulation of enzyme secretion could not be achieved by lymphokines or phorbol esters. However, release could be blocked by treating cells with cycloheximide (5 micrograms/ml) or tunicamycin (0.5 micrograms/ml). Phospholipase A1 was also released by thioglycollate-induced peritoneal macrophages.

Animals↗
PubMed1985

Recording neuromagnetic fields in retinitis pigmentosa.

After stimulation of the left and right half-fields, it is possible to record contralateral visually evoked neuromagnetic fields (VEF) without any reference to the size of the half-field stimulus display. The test reacts extremely sensitively upon each shifting of the half field into the periphery to the left or right. By application of half-field pattern stimuli of an extremely high or low spatial frequency, characteristic deviation angles are obtained for both the spatial frequencies after evaluation of the VEF amplitudes. By this method the foveal acuity in RP can be investigated with an objective procedure to a very high degree of accuracy.

Fovea Centralis↗
PubMed1985

[Specific gastrointestinal manifestations of a generalized cytomegalovirus infection in a patient with acquired immune deficiency syndrome].

In a patient with AIDS, severe cytomegalovirus (CMV) infection dominated with gastro-intestinal and retinal involvement. The gastro-intestinal signs--diarrhoea and recurrent vomiting--correlated with the destruction of the tunica muscularis of the digestive tract seen at post-mortem. The CMV retinitis caused an almost complete loss of sight, the consequence of extensive destruction of the retina. In addition to the generalized CMV infection and disseminated Kaposi's sarcoma, which also involved the gastro-intestinal tract and caused discrete histopathological changes, post-mortem examination revealed a malignant lymphoma of the brain.

Acquired Immunodeficiency Syndrome↗