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Biomedical subjects

M Heller

Publications and source records attributed to M Heller.

At least 19 recordsLinked to original sources
PubMed1979

Partial and incomplete oxidation of palmitate by cultured beating cardiac cells from neonatal rats.

The discrepancy in the rate of [14C]O2 formation from either [1-14C]- or [16-14C]palmitate is demonstrated and could be explained by the preferential formation of L-(+)-3-hydroxybutyrate from the four carbon atoms at the omega terminus. The identity of this product as L(+)-3-hydroxybutyrate was established and shown to be the major component of the radioactive products in the extracellular medium from palmitate based on (a) ion-exchange chromatographical properties, (b) gas-liquid chromatography, (c) mass spectrometric analysis, (d) stereoisomeric separation, and (e) its very low rate of utilization by the cells. We therefore propose a shunt to the oxidation of palmitate in these cells occurring at the stage of L(+)-hydroxybutyryl-CoA which undergoes deacylation causing the product to be transported outside the cell.

Animals↗
PubMed1979

Intracellular lipase activities in heart and skeletal muscle homogenates. The absence of trierucin cleavage by the heart: a possible biochemical basis for erucic acid lipidosis.

Rat heart and skeletal muscle homogenates were compared for their intracellular lipolytic activity towards a series of saturated and unsaturated triglycerides from trilaurin (C12:0) to trierucin (C22:1). It is shown that for all triglycerides esterified with fatty acids from C12 to C18, lipolytic activity in heart homogenates was higher than in skeletal muscle homogenates. For these triglycerides there was no relationship between the fatty acid chain length and the lipolytic activity. In both homogenates cleavage of unsaturated triglycerides was higher than cleavage of the homologous saturated triglyceride. Lipolysis of tri-delta-11-eicosenoin (C20:1) was similar in both homogenates but much lower than lypolysis of other triglycerides. Although cleavage of trierucin (C22:1) was very low in skeletal muscle homogenates, it was undetectable in heart homogenates, even when enzyme concentration was increased. A mixture of triglycerides did not show preferential hydrolysis of any simple triglyceride. Trierucin was the only triglyceride that did not complete for lipolytic activity and only with heart homogenates, which shows that that lipase(s) do not cleave trierucin. The absence of lipolytic activity towards trierucin in heart homogenates could explain the selective accumulation of erucic acid-rich triglycerides in hearts of animals fed a diet with a high erucic acid content.

Animals↗
PubMed1979

[Paget's disease--manifestations in the vertebral colum. Computer tomographic investigations (author's transl)].

Computer tomography has been found to be of value in the study of deformities and narrowing of the spinal canal in 52 patients with Paget's disease of vertebral bodies. To a limited extent it can also be used for evaluating the intervertebral foramina. Deformities of the spinal canal were classified into three degrees of severity. The most severe changes were found in the lower thoracic region. The presence of neurological complications is an indication for CT studies.

Aged↗
PubMed1979

[Computer tomography of the sacroiliac joints (author's transl)].

Computer tomography, like conventional radiography, can demonstrate inflammatory, degenerative or reparative, traumatic and neoplastic lesions of the sacroiliac joints. In some cases computer tomography adds important information, for instance as regards soft tissue changes near the S.I. joints in the presence of neoplastic or posttraumatic lesions (tumour extension, hematoma). Computer tomography is also able to demonstrate minor disalignment of the sacro-iliac joints (so-called sacro-listhesis).

Bone Diseases↗
PubMed1979

[Computed tomography of soft tissue sarcomas (author's transl)].

CT findings in 50 patients with histologically verified soft tissue sarcomas are presented. In nearly all the cases the cross-sectional view and the higher resolution of density make it possible to determine exactly location of the tumors, their size and relationship to adjacent structures. Thus CT opens a new dimension, which is of great value for staging and therapy treatment planning. The high rank of CT in the follow-up after therapy and the detection of recurrent tumor is demonstrated. The contribution of CT, however, to the anatomic characteristics and its prospective value with the regard to soft tissue tumor is less important. Further limits of the method are discussed.

Humans↗
PubMed1979

[X-ray morphology of osteodystrophia deformans Paget (author's transl)].

Osteodystrophia deformans Paget is a frequent and localised disease of the skeleton in elderly persons. The x-ray morphology of the disease is not uniform. It depends on the site at the skeleton, on the design of the affected bone, and on the stage and course of the disease. Basing on 71 own observations, the various types of manifestation are discussed and both their characteristic and non-typical pattern explained. Attention is drawn to the complications which can result from involvement of the individual parts of the skeleton.

Aged↗
PubMed1979

[Preliminary pharmacokinetics of metoclopramide in humans. Plasma levels following a single oral and intravenous dose (author's transl)].

A quantitative thin-layer chromatographic method is discribed for the determination of metoclopramide in human plasma for the 40--320 ng/ml range. Similar plasma levels were observed after single oral dosing with capsules (5 X 11.62 mg metoclopramide X 2 HC'L X H2O) and i.v. injection (2 X 11.62 mg metoclopramide X 2 HCl X H2O). The shape of the plasma level curve after i.v. administration indicates the presence of an open two-compartment model for metoclopramide in humans. Following a very short distributive phase an elimination phase is observed with a half-life of 3--6 h over the period studied. The present data suggest that under the conditions employed in this study metoclopramide is bioavailable by only about 50%; a "first-pass" metabolism is indicated.

Administration, Oral↗
PubMed1978

Phospholipase D.

Explore the source record for details and available documents.

Amino Acids↗
PubMed1977

Plasma membranes from cardiac cells in culture. Enzymatic radio-iodination, evaluation of preparation and properties of the sarcolema.

Plasma membranes from heart (sarcolemma) were prepared by the method of Kidwai, A.M. (1975) Methods in Enzymology (Fleischer, S. and Packer, L., eds.), Vol XXXIA, pp. 134--144, Academic Press, New York). On many occasions the sarcolemmal fraction identified by the enzyme markers such as (Na+ + K+)-ATPase banded at heavier densities (d greater than 1.25 g/ml) than expected for plasma membrane (d less than 1.15 g/ml). Radio-iodination of the membrane was added as an independent marker and conditions for the reproducible preparation of the sarcolemma were studied. Cultured heart cells were enzymatically iodinated under conditions which did not affect viability and labeled primarily the sarcolemma. The distribution of radioactivity in homogenates of cultured cells on the density gradient corresponded to that of the enzymes' activity. The best sarcolemma preparation was obtained with 0.3 M KCl extraction of heart homogenates in the presence of 0.05 M pyrophosphate, especially if the salt was also present during the fractionation by density gradient centrifugation. Alterations in the density were also observed with erythrocytes and cultured liver cells' plasma membrane. The data suggests a meta-stable state of the plasma membranes due to handling or storage which could cause alterations of some of their physical properties (e.g. density).

Adenosine Triphosphatases↗
PubMed1976

Enzymatic hydrolysis of 1-monoacyl-SN-glycerol-3-phosphoryl-choline (1-lysolecithin) by phospholipases from peanut seeds.

Hydrolysis of 1-lysolecithin (1-acyl glycerophosphorylcholine [1-acyl GPC]) by preparations of phospholipase D from peanut seeds was investigated. 1-Lysolecithin was hydrolyzed at a much slower rate than phosphatidylcholine (lecithin). Although Ca+2 ions are required for the cleavage of lecithin by the enzyme, their effect on the hydrolysis of lysolecithin depended upon the concentration of the substrate: at 0.2 mM 1-lysolecithin, Ca+2 ions increased the reaction rates, whereas at concentrations of the substrate lower than 0.1 mM, Ca+2 ions were inhibitory. A broad pH activity curve between 5 and 8 was obtained with higher rates in the alkaline range, both in the absence and presence of Ca+2 ions. The increased hydrolysis of lysolecithin due to Ca+2 was noticed over the entire pH range. Upon storage of the enzyme solutions at 4 C, decreased rates of hydrolysis of lecithin were observed, with t 1/2 values of ca. 50 and 100 days depending on the purity of the preparation. During the same period, no reduction occurred in the activity of these preparations on lysolecithin as substrate. The effects of Ca+2 ions and the analysis of the products of 1-acyl GPC cleavage by the enzyme preparations revealed the presence of more than one enzyme and the formation of the following compounds: lysophosphatidic acids (1 acyl glycerophosphoric acids), free fatty acids, glycerophosphorylcholine, and choline. The possible pathways leading to the degradation of lysolecithin and the formation of these products include reactions catalyzed by lysophospholipase A1 (lysophosphatidylcholine 1-acyl hydrolase, E.C. 3.1.1.5) and a phosphodiesterase (L-3-glycerylphosphorylcholine glycerophosphohydrolase, E.C.3.1.4.2), in addition to phospholipase D (phosphatidyl-choline phosphatidohydrolase, E.C. 3.1.4.4).

Arachis↗
PubMed1976

Interactions of phospholipase D with 1,2 diacyl-sn-glycerol-3-phosphorylcholine, dodecylsulfate, and Ca2+.

Some properties of the pure, soluble phospholipase D (phosphatidycholine phosphatido hydrolase, EC 3.1.4.4) interactions with phosphatidyl choline (1,2 diacyl-sn-glycerol-3-phosphoryl choline) in a system also containing dodecylsulfate and Ca2+ ions were studied. Concentrations of Ca2+ greater than 50 mM were necessary both for activity and adsorption of the enzyme to the "supersubstrate." Ethylenediamine tetraacetic acid caused inhibition of activity, greater than one would expect from its chelating capacity. A nonlinear increase in activity with the increase of enzyme protein was observed, suggesting a subunit aggregation into a higher mol wt protein, catalytically more active. Upon centrifugation of the supersubstrate-enzyme complex at 4.5 X 10(5) g-min at 30 C, most of the substrate molecules sedimented regardless of the pH. The reverse was true when centrifugation was done at 1 C. Phospholipase D hydrolyzed phosphatidylcholine molecules present in the supersubstrate at temperatures around 0 C at a rate 1/5 that of a maximal value measured at 30 C. The Arrhenius plot was linear in the range from 0 to 30 C, and at that temperature the curve broke with a smaller slope. Activation energy of 9.1 Kcal/mol, below 30 C, was calculated. Adsorption of the enzyme to the sedimentable supersubstrate occurred at pH 8.0, regardless of temperature. At pH 5.6, a considerable portion of phosphatidylcholine was degraded at 30 C, thus minimizing the capacity of the supersubstrate to adsorb the enzyme. Although Mg2+ could replace Ca2+ in the formation of sedimentable supersubstrate, it neither assists in adsorption of the enzyme nor in activation of the phosphatidylcholine hydrolysis.

Binding Sites↗
PubMed1976

A specific receptor for retinol binding protein as detected by the binding of human and bovine retinol binding protein to pigment epithelial cells.

By means of autoradiographic techniques the specific plasma carrier of retinol, namely retinol binding protein (RBP) in a radioactive form (retinol-125I.RBP), bound specifically in vivo to the choroidal surface of intact, isolated bovine pigment epithelial cells. The retinol-125I.RBP did not bind to the retinal surface of the pigment epithelial cells nor did not bind to photoreceptors. Retinol is normally provided to the retina from the blood via a specific complex formation with a receptor on the chordial surface of the pigment epithelial cells. Retinol metabolism might be deranged in some diseases through a defect in the pigment epithelial receptor for RBP.

Animals↗
PubMed1975

Membrane-bound enzymes. III. Protease activity in leucocytes in relation to erythrocyte membranes.

Protease activity was detected in membranes of human bovine erythrocytes prepared by the conventional procedures which include washing and removal of the "buffy layer". The enzyme was extracted by 0.75 M KCNS or (NH4)2SO4 and was activated by 0.4 to 0.5 M of the same salts. Colored, particulate hide powder-azure, membrane fractions and soluble proteins such as hemoglobin, casein or albumin were susceptible to hydrolysis by the membraneous protease. Partial purification of the enzyme was accomplished through disc-gel electrophoresis on polyacrylamide in the presence of 0.25% positively charged detergents like cetyltrimethylammonium bromide. An alkaline protease (pH 7.4) with properties similar to those of the erythrocyte enzyme was found in leucocytes. The similarity between the properties of the leucocytic and erythrocytic proteases and the correlation of the activity in erythrocyte membranes with content of white cells in these preparations, suggest that enzymatic activities in the contaminating leucocytes are responsible for the activity of membraneous proteases in erythrocytes.

Animals↗