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H Kunze

Publications and source records attributed to H Kunze.

At least 55 records · Page 3Linked to original sources
PubMed1989

Refinement of the Coomassie brilliant blue G assay for quantitative protein determination.

Minor modifications of the Bradford method [1976) Anal. Biochem. 72, 248-254) increase the sensitivity of the Coomassie brilliant blue G microassay for protein quantitation. This is reached by selecting the proper dye source, by alterations in the dye, ethanol, and phosphoric acid concentrations, and by including Triton X-100 in the reaction mixture. The modified assay conditions allow proteins to be detected above 0.2 micrograms and from a solution above 0.4 micrograms/ml. The extinction coefficient of the dye-protein complex was 0.144 +/- 0.010 for 1 microgram bovine serum albumin in the final reaction mixture of 1 ml. In general, the modified procedure exhibits the same specificity, advantages, and drawbacks as described for the original Bradford assay.

Octoxynol↗
PubMed1989

Acid phospholipase A1 in liver--a brief survey.

Acid phospholipase A1 activity in liver (rat, human) is predominantly localized in lysosomes. A minor proportion (less than 3% of the total activity) is also present in the Golgi apparatus and the endoplasmic reticulum, presumably due to enzymatically active precursors of the corresponding lysosomal enzyme. Lysosomal phospholipase A1 is the most important enzyme initiating the intralysosomal catabolism of diacylphosphoglycerides. It has been purified 50,600-fold, with a yield of about 26%. The enzyme prefers phosphatidyl-ethanolamine as a substrate, which at 200 microM and pH 4.5, is hydrolysed at a rate of approximately 8.2 U/mg. Lysosomal phospholipase A1 is a glycoprotein of about 29 kDa with an isoelectric point of pH 5.3. Unspecific extralysosomal endogenous inhibitors of this enzyme are pH range, inorganic cations, and various proteins. Divalent cations are more potent inhibitors than monovalent ones. Most endogenous intra- and extracellular proteins inhibit the enzyme, the cationic species exhibiting high inhibitory potencies, glycoproteins only little. Inhibitory proteins act through their binding to the substrate. Lysosomal phospholipase A1 seems to be an important target in drug-induced lipidosis. This lipid storage disease is caused by various cationic amphiphilic drugs that are trapped intralysosomally by protonation. In lysosomes such compounds raise the pH, interact with the polar lipids to be degraded and the lysosomal lipolytic enzymes, such as phospholipase A1. These mechanisms result in impaired intralysosomal phospholipid degradation and hence in intralysosomal phospholipid accumulation.

Humans↗
PubMed1989

Cerebral dysfunction with evidence of cerebral HIV infection amongst asymptomatic HIV seropositive subjects.

Twelve asymptomatic HIV seropositive subjects ages 21 to 40 years were examined for serologic evidence of cerebral HIV infection, for cerebral structural abnormalities, and for neuropsychologic evidence of cerebral dysfunction using standard methods. Eleven of the 12 had antibody to HIV in the cerebrospinal fluid (CSF). Nine subjects had oligoclonal immunoglobulins in the CSF, of whom five had some for which there were no corresponding serum oligoclonal immunoglobulins ('unique' oligoclonal immunoglobulins). Intracerebral synthesis of HIV specific antibodies was demonstrated for four subjects. Significant deficits of memory and frontal lobe function were found in five of the 12 subjects. Subjects who had oligoclonal immunoglobulins unique to the CSF all had significant neuropsychological abnormalities. No structural cerebral abnormalities were demonstrated using CT scanning for any subject tested. These results support other evidence that HIV is neurotropic and capable of directly inducing brain damage even in immunologically normal subjects. Tests of memory and frontal lobe function are frequently abnormal in patients with early HIV infection, and identify as abnormal a similar group of patients to immunological or biochemical tests which might indicate cerebral HIV infection.

Acquired Immunodeficiency Syndrome↗
PubMed1989

An improved purification procedure for rat liver lysosomal phospholipase A1.

A purification procedure is presented for the isolation of lysosomal acid phospholipase A1 (PLA1) from livers of non-pretreated rats, in a high yield and purity. The purification starts from a crude mitochondrial-lysosomal fraction. PLA1 is solubilised and subsequently purified by chromatography on concanavalin A-Sepharose, by chromatofocusing, and by gel filtration. After chromatofocusing, the enzyme is already purified 50200-fold with a yield of 50%, and after gel filtration 56600-fold with a yield of 7%. Purified PLA1 exhibits a specific activity of approx. 8.2 mumol phosphatidylethanolamine (preferred substrate) hydrolysed per min per mg protein, and upon chromatofocusing an apparent isoelectric point of 5.3 Gel filtration of purified PLA1 suggests a molecular mass of about 29 kDa, whereas in SDS-PAGE two proteins of 27 kDa and 55 kDa (mass ratio about 1/2) were visualised.

Animals↗
PubMed1988

Inhibitors of liver lysosomal acid phospholipase A1.

Lysosomal acid phospholipase A1, as well as other lysosomal enzymes, may be released under pathophysiological conditions into extralysosomal compartments. As shown here, several unspecific mechanisms exist which inhibit the hydrolysis of membrane diacylphospholipids by lysosomal acid phospholipase A1 and hence prevent an uncontrolled membrane destruction. These findings were obtained by employing partially purified rat liver lysosomal acid phospholipase A1 and sonicated radioactively labeled phosphatidylethanolamine or phosphatidylcholine as substrate. The inhibitory principles found include (1) pH, (2) inorganic cations, and (3) various proteins. Inorganic cations and proteins, however, inhibited lysosomal acid phospholipase A1 activity only below pH 6.0, and inhibition never exceeded 96%. Of the inorganic cations studied, the divalent species, as compared to the monovalent one, impaired lysosomal acid phospholipase A1 activity at significantly lower concentrations. Virtually all of the intracellular and extracellular proteins studied inhibited the enzyme activity, but the inhibitory potencies of the different proteins varied considerably. In general, basic and hydrophobic proteins were the most potent inhibitors, whereas glycoproteins appeared to be less inhibitory. The degree of inhibition of the enzyme activity in both proteins and inorganic cations depended on the substrate concentration and not on that of the enzyme. Binding studies provided evidence for inhibitor-substrate and against inhibitor-enzyme interactions.

Animals↗
PubMed1988

Acid phospholipase A activities in rat hepatocytes.

Cultured rat hepatocytes exhibit acid phospholipase A activity. On the basis of product formation from stereospecifically radiolabeled phosphatidylethanolamine substrates, phospholipases A1 and A2 have been identified with optimal activities at pH 4.5. According to subcellular fractionation studies, the acid phospholipases in hepatocytes appear to be located in the lysosomal compartment. Application of specific inhibitors of the biosynthesis, glycosylation, and translocation of lysosomal enzymes in hepatocyte cultures suggests a half-life of approx. 1 day for the acid lysosomal phospholipase A1. About the same value for the half-life was obtained for the lysosomal marker enzymes, acid phosphatase and beta-N-acetyl-D-hexosaminidase.

Animals↗
PubMed1988

Inhibition of liver lysosomal acid phospholipase A1 by blood serum proteins.

Pathophysiological conditions may lead to a release of lysosomal acid phospholipase A1 like that of other lysosomal enzymes into the blood stream. As shown here, various serum protein fractions, obtained by dye-ligand affinity chromatography, inhibit phosphoglyceride hydrolysis by lysosomal acid phospholipase A1 in vitro. Their inhibitory potencies vary considerably, and the degree of inhibition depends on the substrate concentration. A delayed phospholipid flotation rate in sucrose gradients in the presence of one of the more potent inhibitory serum proteins, serum albumin, suggests that the inhibition is due to inhibitor-substrate interactions. Although lysosomal phospholipase A1 activity at blood pH is extremely low, serum proteins may contribute to protect biomembranes which are exposed to the vascular lumen against uncontrolled destruction by this enzyme.

Animals↗
PubMed1987

Fractionation, biochemical characterization and lysosomal phospholipases of human liver.

Human liver was homogenised and fractionated by differential centrifugation, and the subcellular fractions were characterised biochemically. Absolute values and distribution patterns of protein and marker enzyme activities obtained from human liver have also been compared with those from rat liver. In addition, acid phospholipase activities have been studied in human liver. On the basis of product formation from stereo-specifically radiolabeled phosphatidylethanolamine substrates, lysosomal phospholipases A1 and A2 with optimal activities at pH 4.7 have been identified in human liver. Acid phospholipase C and lysophospholipase activities, however, were not found in human liver. Cationic amphiphilic drugs inhibited the activities of the acid phospholipases A in human and rat liver lysosomes to about the same extent.

Animals↗
PubMed1987

Disintegration of isolated cells.

A simple device has been developed for the disintegration of isolated cells in isotonic or hypertonic media. It is based on the extrusion of a cell suspension through a small orifice under controlled pressure. The diameter of this interchangeable orifice has to be adapted to the cell type to be disrupted. The conditions fulfill the requirements for an efficient disruption of the plasma membranes and for good preservation of the particularly fragile subcellular components, lysosomes and peroxisomes, of rat hepatocytes and rat Leydig cells.

Animals↗
PubMed1987

[Developmental status and goals in occupational therapy. The "Guidelines for Occupational Therapy in Psychiatric Hospitals"].

Work therapy, or ergotherapy, is a recognised and permanent part of psychiatric treatment and medical rehabilitation. It is also an essential part of psychiatric diagnosis and therapy; furthermore, it enables the patient to develop and stabilise a realistic image of himself and contributes to the prevention and reduction of damage caused by hospitalism. The present status of work therapy was checked in 74 psychiatric hospitals throughout the Federal Republic of Germany, resulting in the need for further development of present practical procedures. A working group was created by the Federal Ministry of Labour and National Welfare within the framework of the model programme for psychiatry, at the suggestion of a Federal Working Group of the organisations running public mental hospitals in the FRG. The aim of this working group was to develop a specialised concept of work therapy. The group consisted of experts from clinical practice as well as from the Federal German Labour Office Institution, psychiatric consultants of the Federal Government and the Land Governments, as well as from the Land Government sponsors of state social welfare services. The "Guidelines for Work Therapy in Psychiatric Hospitals and Departments of Psychiatry" are officially considered to be a suitable basis for further development work in the field of ergotherapy.

Germany, West↗
PubMed1987

[The action of benzydamine on phospholipase activation].

The effects of the antiinflammatory drug benzydamine (Tantum) on phospholipase activities were determined in vitro, employing various enzyme preparations (rat liver plasma membranes, endoplasmic reticulum, lysosomes; human seminal plasma) and stereospecifically radiolabeled phosphatidylethanolamines as substrates. Fatty acid release from the sn-2 position was inhibited at drug concentrations above 10(-5) mol/l. Concerning the mode of inhibition, a mixed type was found for the soluble phospholipase A2. Impaired fatty acid release from the sn-2 position might contribute to the mechanism of antiinflammatory action of benzydamine by rendering less free precursor acid available for the synthesis of eicosanoids. Fatty acid release from the sn-1 position was inhibited at benzydamine concentrations from 10(-6)-10(-2) mol/l only in lysosomes, whereas in plasma membranes and endoplasmic reticulum it was stimulated, maximally (at 10(-3) mol/l) about 25% and 50%, respectively.

Animals↗