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Biomedical subjects

H G Zimmer

Publications and source records attributed to H G Zimmer.

At least 91 records · Page 5Linked to original sources
PubMed1982

Demonstration of alpha 1-acid glycoprotein (orosomucoid) by double one-dimensional slab gel electrophoresis: evidence for intra- and interindividual variability of the microheterogeneity pattern in health and disease.

This double one-dimensional slab gel electrophoresis technique, in the sequence polyacrylamide gel electrophoresis followed by isoelectric focusing in polyacrylamide gels, permits the selective demonstration and comparison of the micro-heterogeneity pattern of alpha 1-acid glycoprotein (orosomucoid) in as many as 96 human plasma or serum samples on one gel. The electrophoretic analysis is performed on 8 microL of serum or plasma without prior purification. Several hundred samples can be analyzed by one investigator during a working day. Densitometric evaluation of the patterns revealed two new findings: 1) The microheterogeneity pattern can be described by a parameter that is independent of the concentration of orosomucoid in plasma: the center of density of the pattern, with the peak number as coordinate. 2) There is a considerable average shift of the center of density towards more basic components among the patterns obtained for samples from hospital patients. The results suggest that followup of the intra-individual variation of the orosomucoid pattern in health and disease might help in studying the still-uncertain function of this protein as well as the diseases affecting the pattern.

Adult↗
PubMed1981

[Digital image analysis as an optical tool in biochemistry].

Digital image analysis can be used to assist of complement visual perception. In quantifying light intensities it is superior to the human visual system and therefore is an appropriate and useful tool for research. Using microphotometry as an example the physical bases of digital image analysis are explained and the applications of this measuring technique to biochemical analysis are demonstrated.

Computers↗
PubMed1980

Reduction of the isoproterenol-induced alterations in cardiac adenine nucleotides and morphology by ribose.

Continuous intravenous infusion of ribose (200 milligrams per kilogram per hour) for 24 hours induced a marked stimulation of cardiac adenine nucleotide biosynthesis in unanesthetized and unrestrained rats that had been treated with isoproterenol subcutaneously (25 milligrams per kilogram). The diminution of adenine nucleotides characteristic for the action of high doses of isoproterenol was entirely prevented, and the incidence of the isoproterenol-induced myocardial cell damage was significantly reduced when ribose was administered. These results support the view that depletion of adenine nucleotides is involved in the development of cardiac necrosis.

Adenine Nucleotides↗
PubMed1980

Studies on the hexose monophosphate shunt in the myocardium during development of hypertrophy.

In rat hearts hypertrophying because of aortic constriction and isoproterenol administration, the activity of glucose-6-phosphate dehydrogenase and the available pool of 5-phosphoribosyl-l-pyrophosphate were found to be increased, indicating an enhancement of the flow through the hexose monophosphate shunt. In triiodothyronine-treated animals only the cardiac pool of 5-phosphoribosyl-l-pyrophosphate was elevated. In all three models of experimentally induced cardiac hypertrophy, the enhancement of myocardial adenine nucleotide biosynthesis was potentiated by ribose. Since ribose gives rise to a considerable elevation of the available 5-phosphoribosyl-l-pyrophosphate, it appears that this is the limiting factor for the increase of adenine nucleotide biosynthesis in hypertrophying hearts. Constant intravenous infusion of ribose for 24 hr prevented the decrease of myocardial ATP concentration is isoproterenol-treated rats.

Adenine Nucleotides↗
PubMed1980

Restitution of myocardial adenine nucleotides: acceleration by administration of ribose.

In the present study, the influence of ribose on the biosynthesis of myocardial adenine nucleotides was examined in rats in vivo utilizing two experimental models which are characterized by a reduction in the adenine nucleotide content; recovery from oxygen deficiency and application of isoproterenol. 1. The biosynthesis (= de novo synthesis) of cardiac adenine nucleotides was enhanced by 90% during the first 60 min of recovery from five intermittent periods of asphyxia of 4.5 min duration (Table I). 2. Isoproterenol induced a stimulation of myocardial adenine nucleotide synthesis in a dose-dependent manner amounting to 640% three hours after s.c. administration of 25 mg/kg (Fig. 1). 3. Ribose which bypasses the hexose monophosphate shunt in the myocardium and which leads to an elevation of the available pool of 5-phosphoribosyl-1-pyrophosphate (PRPP), stimulated the biosynthesis of adenine nucleotides in the heart, but not in liver and kidney, of rats one hour after i.v. application of a single dose of 100 mg/kg from 6 nmoles/g/h to 27 nmoles/g/h (Fig. 2). 4. When ribose was constantly infused during the first 60 min of recovery from asphyxia, the enhancement of cardiac adenine nucleotide biosynthesis was further stimulated from 12.6 nmoles/g/h to 20.5 nmoles/g/h (with 500 mg ribose/kg/h) and to 43.4 nmoles/g/h (with 1 000 mg ribose/kg/h) (Fig. 3). 5. Continuous I.V. infusion of ribose (200 mg/kg/h) for 24 hours in isoproterenol-treated rats during a 13-fold increase in myocardial adenine nucleotide biosynthesis compared with the control (Fig. 4). In this condition, the isoproterenol-induced decline in the adenine nucleotide level did not occur (Table II).

Adenine Nucleotides↗
PubMed1980

Early metabolic alterations during the development of experimentally induced cardiac hypertrophy.

The main biochemical features of protein synthesis in the myocardium are described as well as several metabolic alterations that occur during the very early stages in three models of cardiac hypertrophy resulting from pressure overload in vivo and in vitro, application of a high dose of isoprenaline and repeated daily administration of triiodothyronine. Furthermore, both mechanical and metabolic factors possibly participating in the development of cardiac hypertrophy are discussed and critically evaluated.

Adenosine Triphosphate↗
PubMed1980

Isoproterenol-induced enhancement of myocardial glucose-6-phosphate dehydrogenase.

Isoproterenol enhanced the activity of glucose-6-phosphate dehydrogenase and the availability of 5-phosphoribosyl-1-pyrophosphate in the rat myocardium, which indicates an increased flow through the hexose monophosphate shunt. The stimulatory effect of isoproterenol on cardiac glucose-6-phosphate dehydrogenase activity, could be prevented by beta-receptor blockade with atenolol, but not by the calcium-antagonistic compound D 600.

Adenine Nucleotides↗
PubMed1979

Long-term effects of ribose on adenine nucleotide metabolism in isoproterenol-stimulated hearts.

1. Among the precursor substances tested 1-14C-glycine is the most suitable for measuring rates of AN biosynthesis in rat hearts in vivo. 2. Continuous i.v. infusion of ribose for 24 hours stimulates AN biosynthesis in normal hearts and amplifies the enhancement of this process in hearts of isoproterenol-treated rats. The isoproterenol-induced decline of myocardial ATP is prevented by long-term application of ribose. 3. Elevation of the available PRPP pool mainly mediated by ribose and release of feedback inhibition of PRPP amidotransferase activity by the isoproterenol-induced ATP decline appear to be the optimal conditions required for maximal stimulation of myocardial AN biosynthesis.

Adenine Nucleotides↗
PubMed1979

Digital picture analysis in microphotometry of biological materials.

Automatic evaluation of two-dimensional thin-layer-chromatograms exemplarily demonstrates the applicability of signal processing, image analysis, and pattern recognition to microphotometry by an enlarged dynamic range of the photometer, improved reproducibility by noise reduction, discrimination between objects and background, feature extraction and automatic classification of the results. Emphasis is put on simple procedures which are tested in routine work and can be implemented on minicomputers.

Analog-Digital Conversion↗
PubMed1979

The fluorescence scanning of microgels stained for glycoproteins with fluorescein isothiocyanate-labelled concanavalin A.

A technique is presented which allows one to label and quantitate glycoproteins. Small amounts of protein from biological samples (0.5-2.5 microgram for mixtures and less for individual proteins) are separated by sodium dodecyl sulfate gel electrophoresis on 1-30% polyacrylamide gradient microgels. The gels are stained with Co-omassie Brillant Blue R250 to evaluate relative migration or fixed in 2-propanol/acetic acid and stained with fluorescein isothiocyanate-labelled concanavalin A. The microgels are then scanned using a fluorescence microscope controlled by a computer, although simpler configurations are possible. Standards of known carbohydrate composition (e.g., glucose oxidase) are used for comparative purposes. Glycoproteins in the order of 5-30 ng protein (or 1-5 ng carbohydrate) can be detected without difficulty. This technique may prove valuable in evaluating glycoproteins when the available material is limited.

Animals↗
PubMed1979

A simple, versatile, sensitive and volume-independent method for quantitative protein determination which is independent of other external influences.

A method is described which in principle is a quantitative "spot analysis". 0.5-5 microliter of a protein solution in the concentration range between 0.01-10 mg/ml is used for one determination. The sample is taken up by capillary attraction in a 0.5-, 1-, 2- or 5-microliters capillary and transferred to a cellulose acetate strip. The protein is fixed and stained simultaneously by dipping the cellulose acetate strip into a solution of Amido Black or a benzoxanthene derivative (Hoechst 2495) dissolved in in methanol/acetic acid. After elution of the excess of dye (3 x 5 min) the quantitative evaluation can be performed in different ways: 1) The sample is fixed and made transpartent by incubation in dioxane/1-butanol and evaluated densitometrically (Amido Black 10B) or 2) the evaluation is performed in situ by spot fluorometry (Hoechst 2495). 3 The sample can be dissolved together with the acetate layer completely in dioxane, dimethylsulfoxide or N,N-dimethylformamide and evaluated photometrically or 4) fluorometrically. 5) Highest sensitivity is reached if the fluorochrome (Hoechst 2495) bound to the protein is eluted with 15% NH4OH and measured fluorometrically. There is a linear correlation with a correlation coefficient of 0.999 between the fluorescence and a protein amount of 10 ng-20 micrograms. In addition to its simplicity, the method has the advantage of being independent of or well-defined against other external influences, e.g., sodium dodecyl sulfate, mercaptoethanol, Triton X-100, etc. The stainability of a protein with Amido Black is influenced stoichiometrically by sodium dodecyl sulfate (not by mercaptoethanol) whilst the staining with Hoechst 2495 is not at all affected. As there is linear correlation between the area of a spot on an acetate layer and the volume applied in the range between 0.5 and 5 microliters, (only influenced stoichiometrically by the protein concentration in that volume, which in turn is measured by staining with Amido Black), then with a simple iterative calculation on the basis of suitable calibration curves, it is easily possible to determine a protein concentration in mg/ml even in an unknown volume between 0.5 and 5 microliters.

Capillary Action↗
PubMed1979

Improved microphotometry by compensating for fluctuations in the illumination.

Behind a beam-splitter in the illuminator, the irradiation of an area conjugated to the object plane is measured by a silicon photodiode and used as a reference signal. Analog division of the photomulitplier signal by this reference acts like stabilizing the light source by a factor greater than 25. A technical realization of the optical and electronical components as well as experimental results are described.

Microscopy, Fluorescence↗
PubMed1978

Stimulation of myocardial adenine nucleotide biosynthesis by pentoses and pentitols.

In rats, pentoses and pentitols, intravenously injected in a single dose of 100 mg/kg, induced a considerable enhancement of the available pool of 5-phosphoribosyl-1-pyrophosphate and of the rate of adenine nucleotide biosynthesis in the heart, but not in liver and kidney. De novo synthesis of adenine nucleotides not detectable in skeletal muscle of normal rats became measurable after application of ribose. The stimulatory effect of isoproterenol on myocardial adenine nucleotide biosynthesis could be further potentiated by ribose and xylitol, but not by glucose. The isoproterenol-induced decrease of cardiac adenine nucleotide concentrations could be almost completely prevented by repeated administrations of ribose. Thus, pentoses and pentitols in combination with beta-receptor stimulation markedly and quite specifically enhance adenine nucleotide biosynthesis in the rat heart. The results indicate that the increase in the available pool of 5-phosphoribosyl-1-pyrophosphate is an important factor for the enhancement of cardiac adenine nucleotide biosynthesis. Moreover, the availability of 5-phosphoribosyl-1-pyrophosphate and the rate of de novo synthesis of adenine nucleotides in the heart seem to be limited by the flow through the hexose monophosphate shunt.

Adenine Nucleotides↗