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Biomedical subjects

E Lindner

Publications and source records attributed to E Lindner.

At least 37 records · Page 2Linked to original sources
PubMed1988

Extraction of proteins within ultrathin-layer polyacrylamide electrophoresis (SDS-PAGE) and isoelectric focusing (PAGIF) of cryostat sections and tissue culture specimens.

Separations on a micro- and ultramicroscale by electrophoresis and isoelectric focusing of protein quantities between 10(-6) and 10(-12) g have notable interest, particularly in cytology and histology. We performed the methods of ultrathin-layer polyacrylamide horizontal electrophoresis, isoelectric focusing and protein mapping with some modifications in order to study protein extraction and applied them for cryostat sectioned muscle tissues and singular dorsal root ganglia of the chicken in tissue culture. Further we established an extraction chamber for histological specimens. The basis for ultrathin-layer electrophoresis is the ultrathin (0.12 mm-0.36 mm) polyacrylamide gel on glass plates or microscopic slides. This method allows a considerable reduction of the amount of proteins at the range of 10(-9) g and is thus appropriate for direct extraction of proteins within electrophoresis (10 min, 5 mA 200 V) or isoelectric focusing (10 min, 10 mA, 500 V) of cryostat-sections (7-20 micron thickness) or tissue culture specimens. The advantages of these techniques for extraction of soluble proteins in immunohistochemistry as well as for handling to obtain optimal resolution (compared with electrophoresis of conventional extracted proteins) will be demonstrated.

Animals↗
PubMed1987

Light-microscopic studies on spatial and temporal binding of the lectins concanavalin A, wheat-germ agglutinin and peanut agglutinin in early rat odontogenesis.

The spatial distribution and temporal expression of alpha-D-mannosyl(glucosyl)-, N-acetyl-D-glucosaminyl- and beta-D-galactosyl residues as detected by peroxidase-conjugated lectins correlated with early odontogenic events in six principal developmental stages (fetal days 13.5, 14, 15, 17, 18.5 and 19.5). The odontogenic epithelium of 13.5- and 14-day-old fetuses was characterized by strong concanavalin A (Con A) binding and between days 17 and 19.5, the stellate reticulum displayed strong peanut agglutinin (PNA) binding. Between 15 and 19.5, differentiation of dental ectomesenchyme was characterized by a rhythmic expression of terminal galactosyl residues shown by PNA-binding. At the developing dental basement membrane, there were various carbohydrate-specific regions. At days 13.5 and 14, the odontogenic basement membrane was specific for N-acetyl-D-glucosamines detected by wheat-germ agglutinin (WGA). The results suggest that the carbohydrates present at the inner dental basement membrane at days 17 to 19.5 may be involved in cell-matrix interactions during cytodifferentiation.

Animals↗
PubMed1987

Subpassaging cells on microcarriers: the importance for scaling up to production.

Optimization of microcarrier processes is dependent upon efficient, serial subcultivation routines. Established methods have been modified for a high degree of cell detachment from microcarriers, and transfer of a maximum number of viable cells from one culture to the next during the scale up process. Cultures of MRC-5 and Vero cells were studied, and cell inocula were obtained from different growth phases (i.e. exponential versus stationary) to investigate growth in subsequent cultures. Microcarrier cultures containing confluent cells were washed with EDTA-PBS and then exposed to trypsin (185 U/ml) in PBS (pH 8.0, 37 degrees C). 95-100% of the cells detached from the microcarriers with a viability greater than 95% following a 10 minute exposure to the trypsin. The presence of residual trypsin in the inoculum was investigated with respect to subsequent growth, and no significant effect was found. The methods developed at the laboratory scale (0.25 to 1.5 l cultures) were successfully applied to pilot scale (1 to 100 l cultures), and resulted in split ratios of up to 1:10 for MRC-5 cells and 1:100 for Vero cells. These results show that the modified subpassaging method and an optimal cell inoculum are vital in establishing efficient, industrial scale microcarrier processes.

Animals↗
PubMed1987

Alternatives for harvesting cells grown on microcarriers: effects on subsequent attachment and growth.

In order to facilitate the subpassaging of cells in microcarrier cultures for scaling up culture volumes, alternative procedures for harvesting cells from microcarriers were investigated. A variety of enzymes including trypsin and dextranase were tested separately and in combination to evaluate cell viability after detachment, recovery, and subsequent attachment and growth of cells following inoculation of the cells in the next microcarrier culture. Treatment of confluent microcarriers with dextranase detached cells efficiently and with high viability and in addition totally digested the dextran-based matrix of Cytodex, thus avoiding the possible need to separate the harvested cells from the microcarriers. Dextranase alone resulted in cells harvested as sheets, but if used in combination with trypsin, a single cell suspension of harvested cells was obtained.

Animals↗
PubMed1985

Microspectrophotometric and scanning microphotometric studies of carp (Cyprinus carpio L.) erythrocytes.

Carp (Cyprinus carpio) hemoglobin readily autoxidizes in blood smears. Quantification of Soret-band absorbance in individual erythrocytes by means of scanning cytophotometry therefore requires more elaborate methods of preparation of blood samples. Of the fixatives that have been tested, suspension of whole blood in isotonic salt solutions containing glutaraldehyde was most suitable. Glutaraldehyde-fixed red blood cells are totally resistant to hemolysis. In the course of fixation, hemoglobin is transformed to methemoglobin. Spectrophotometry indicated extensive similarities between glutaraldehyde-fixed carp methemoglobin and human methemoglobin. In aqueous solutions, the intensity of the Soret-peak was pH-dependent. The allosteric modifier organic polyphosphate caused an R----T transition, resulting in increased molar extinctions. Dried preparations showed Soret-spectra that were not influenced from either pH or organic polyphosphate concentration of the aqueous suspensions in which the erythrocytes had been stored. The same was true for slide preparations of cyanomethemoglobin, easily derived from methemoglobin on addition of potassium cyanide. In the absence of oxygen fresh blood cells from carp slowly transform their hemoglobin into deoxyhemoglobin. Spectra of the intermediate stages of deoxygenation, Hb4(O2)3, Hb4(O2)2 and Hb4(O2), as well as mixtures of these intermediates, could be monitored.

Animals↗
PubMed1984

[Effect of forskolin eyedrops on intraocular pressure in healthy males].

Suspensions of Forskolin in concentrations of 0.3; 0.6; and 1.0% decreased effectively the intraocular pressure of healthy subjects when instillated in the conjunctival sac. The suspensions were compared with placebo in double blind studies. The maximum effect was reached 3 hours after application of the 0.3% (22.8%) and 0.6% (27.8%) suspensions and 4 hours after the 1.0% (26.5%) suspension. The higher concentrations decreased the intraocular pressure to the same extent as the lowest concentration but the effect lasted longer: 4 hours after instillation of the 0.3% suspension, 5 hours after instillation of the 0.6% suspension and 7 hours after the 1.0% suspension. The suspensions were well tolerated. Subjective sensations like burning, itching and augmentated lacrimation were observed only in a minor amount and for a short period of time.

Adult↗
PubMed1984

Perfluorochemical perfusion of the isolated guinea pig heart.

We studied the influence of a perfluorochemical (PFC) emulsion on the ultrastructure and function of the isolated perfused guinea pig heart compared to a Krebs-Henseleit solution. The PFC perfusion enhanced the force of contraction and reduced the coronary flow rate, but had no influence on the frequency and the oxygen consumption. The positive inotropic action of K-strophanthin and isoproterenol was slightly strengthened, whereas the beta-adrenergic antagonism by propranolol and the vasodilatation by glycerol trinitrate remained unchanged. The positive chronotropic action of isoproterenol was reduced during PFC perfusion. No histological differences depending on the perfusion medium were observed. It is concluded that PFC perfusion improves the functional state of the Langendorff preparation.

Animals↗
PubMed1984

Hoe 263, a new substance with calcium channel antagonistic activity.

Hoe 263 inhibited the contraction of the potassium-depolarized pulmonary artery of the guinea pig. In this experiment it was slightly more active than verapamil. The calcium uptake of the potassium-depolarized pulmonary artery was inhibited by Hoe 263 more effectively than by prenylamine. The upstroke velocity of the potassium-depolarized papillary muscle of the guinea pig was depressed with similar concentrations of Hoe 263 and verapamil. In the (3H)-nitrendipine binding test, Hoe 263 was effective at similar concentrations as prenylamine and verapamil. The positive inotropic effect of K-strophanthin was depressed by Hoe 263 at concentrations which were comparable with those necessary for verapamil.

Animals↗
PubMed1984

L-3,4-(3-3,4-dimethoxyphenethylamino-2-hydroxypropoxy)-phenyl- crotonic acid nitrile.HCl (Hoe 224), a beta-blocking agent with high beta 1-selectivity.

L-3,4-(3-3,4-Dimethoxyphene-ethylamino-2-hydroxypropoxy)-phenyl-++ +crotonic acid nitrile X HCl (Hoe 224) has beta 1-blocking action. In the isolated left atrium of the guinea pig, the ED50 necessary to counteract the positive inotropic action of 2 ng/ml isoprenaline (isoproterenol) was determined as 10.3 ng/ml in comparison to the ED50 of propranolol 2.7 ng/ml. On the isolated right atrium of the same animal, the ED50 for inhibition of increased heart rate brought about by 2 ng/ml isoprenaline was 29.5 ng/ml in comparison to the ED50 of propranolol 13.5 ng/ml. On the isolated tracheal chain of the guinea pig 40 micrograms Hoe 224/ml also inhibited relaxation induced by 50 ng isoprenaline/ml only by 31%. The ED50 for propranolol in this experiment was 1.2 ng/ml. Therefore, Hoe 224 is a very specific beta 1-blocker. In the dog anaesthetized with pentobarbital the ED50 of Hoe 224 for depression of dp/dt increase by 0.1 mg isoprenaline/kg i.v. was determined as 85 micrograms/kg i.v. Under the same conditions, the ED50 for propranolol was 10 micrograms/kg i.v., for atenolol 17 micrograms/kg i.v., for practolol 56 micrograms/kg i.v. In the conscious dog, 1.6 mg Hoe 224/kg orally depressed the increase of dp/dt brought about by 0.1 microgram isoprenaline/kg i.v. by 50%. The beta 2-blocking effect of Hoe 224 intraarterially against vasodilating effect of 0.01 microgram isoprenaline/kg given intraarterially in the A. femoralis of anaesthetized dogs was very weak. 100 micrograms Hoe 224/kg reduced the effect of isoprenaline only by 23%, but 2 micrograms propranolol/kg intraarterially reduced this effect by 61%.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic beta-Antagonists↗
PubMed1983

The action of forskolin on muscle cells is modified by hormones, calcium ions and calcium antagonists.

Forskolin, a drug isolated from the Indian plant Coleus forskohlii, exerts its actions on cells by directly activating the catalytic subunit of adenylatecyclases. The primary effect on heart muscles is the positive inotropic one, at higher forskolin concentrations, an acceleration of the pacemaker activity can be observed. External Ca2+ is required for this augmentation of contraction, verapamil, prenylamine and tetrodotoxin depress these effects. The action of forskolin and digitalis glycosides are to a certain degree additive. Incubation of rat heart slices with forskolin depresses the membrane bound Na+K+-ATPase activity. In smooth muscle cells, forskolin lowers the contractions, evoked by K+, norepinephrine and by angiotensin II. The results are discussed in respect to a forskolin induced enlargement of the Ca2+-uptake of heart muscle cells and a lowering of the Ca2+-sensitivity of the contractile system of smooth muscle cells.

Adenylyl Cyclases↗
PubMed1982

Effects of calcium antagonists on coronary spasm and pulmonary artery contraction in comparison to their antagonistic action against K-strophanthin in isolated guinea pig atria.

The contraction of the potassium depolarized pulmonary artery of the guinea pig was diminished by the calcium antagonists nifedipine, gallopamil, diltiazem, verapamil and prenylamine. The drugs are listed here in order of activity. The uptake of 45Ca of the depolarized pulmonary artery was reduced by nifedipine, verapamil and prenylamine in this order of activity. The depression of the coronary flow of the isolated guinea pig heart, which was brought about by barium chloride, antigenic rabbit serum or vasopressin plus oxytocin was reduced by infusion of prenylamine. The positive inotropic effect of K-strophanthin on the isolated, electrically stimulated left atrium of the guinea pig heart was reduced by gallopamil, verapamil, prenylamine, diltiazem and nifedipine in this order of activity.

Animals↗
PubMed1981

Ni2+, a new inhibitor of mitochondrial calcium transport.

1. The effect of Ni2+ on respiration, volume changes and Ca2+ movements was investigated in rat liver mitochondria. 2. Ni2+ inhibited Ca2+ uptake into respiring mitochondria, Ca2+-stimulated respiration and swelling in Ca2+ salts, whereas it did not inhibit either state 4 and DNP-stimulated respiration, or swelling in K+ salt in the presence of valinomycin. 3. The inhibitory concentration of Ni2+ dependent strongly on the applied Ca2+ concentration. As revealed by direct methods, 50% inhibition of Ca2+ influx was achieved by approx. 2-fold excess of Ni2+. 4. If added to Ca2+-loaded mitochondria, Ni2+ gave rise to slow Ca2+ release and inhibited uncoupler-induced efflux slightly. 5. It is concluded that Ni2+ is a potent inhibitor of mitochondrial Ca2+ transport. Ca2+ influx is far more sensitive to inhibition than Ca2+ efflux.

Animals↗
PubMed1981

The positive inotropic-acting forskolin, a potent adenylate cyclase activator.

Forskolin is a positive inotropic-acting and blood pressure lowering agent which was isolated from the Indian plant Coleus forskohlii. In isolated heart tissue, forskolin activates a membrane bound adenylatecyclase and a cytoplasmic cAMP-dependent protein kinase to a much higher degree than does isoprenaline. This activation does not require the hormone receptor. In isolated and electrically stimulated left guinea pig atria, the adenylate-cyclase activation by forskolin is the prerequisite for the positive inotropic effect. We therefore postulate the adenylatecyclase activation to be correlated with the positive inotropic effect via an enhanced calcium uptake by the heart muscle cell.

Adenylyl Cyclases↗
PubMed1980

[On the pharmacology of the beta-receptor blocker penbutolol (author's transl)].

1-tert.-Butylamino-3-(2-cyclopentylphenoxy)-propan-2-ol (penbutolol, Hoe 893d) is a beta-adrenergic blocking agent about 4 times more active than propranolol in vivo and in vitro. In comparison to propranolol it is characterized by a longer lasting activity. The antihypertensive effect of penbutolol in spontaneously hypertonic rats is more than 5 times stronger than that of propranolol. Penbutolol reduces basal plasma renin activity in the same dose range as does propranolol but is about 3 times stronger with respect to isoproterenol-induced increase of PRA. Penbutolol is 5 times more potent than propranolol inhibiting isoproterenol-stimulated phosphorylase activity in the isolated heart. In reserpine pretreated rats, penbutolol has a moderate intrinsic sympathomimetic activity (ISA). Penbutolol shows less unspecific actions -- such as negative inotropy or calcium antagonism -- than propranolol. Characteristic parameters of lung function (compliance and resistance) are less affected by penbutolol than propranolol in spite of the fact that penbutolol has a stronger beta-adrenergic blocking effect.

Animals↗