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M J Hardonk

Publications and source records attributed to M J Hardonk.

At least 91 records · Page 5Linked to original sources
PubMed1981

Plasma membrane specialization and intracellular polarity of freshly isolated rat hepatocytes.

It was investigated whether rat hepatocytes maintain their plasma membrane specialization (sinusoidal, lateral and bile canalicular sites) and their intracellular polarity (peribiliary region, rich in lysosomes and poor in mitochondria) after isolation. The morphology of the hepatocytes and the cytochemical localization of marker enzymes for the bile canalicular membrane (alkaline phosphatase, adenosine triphosphatase and 5' nucleotidase), for the lysosomes (acid phosphatase) and for the mitochondria (beta-hydroxybutyrate dehydrogenase and succinate dehydrogenase) were studied in situ and directly after isolation using both light and electron microscopy. The morphology of the cells and the cytochemical activity of acid phosphatase, succinate dehydrogenase and beta-hydroxybutyrate dehydrogenase showed that in isolated cells, as in situ, the lysosomes were concentrated in bands, devoid of mitochondria. Unlike in situ the reaction product of alkaline phosphatase, adenosine triphosphatase and 5'nucleotidase was evenly distributed along the entire plasma membrane of the isolated cells. Morphologically, no tight or gap junctions or desmosomes could be detected in the isolated cells, while the plasma membrane appeared to be homogeneously covered with uniform microvilli. In conclusion it can be stated that during isolation the hepatocytes loose their distinct plasma membrane specialization, but maintain their peribiliary region rich in lysosomes and poor in mitochondria.

Animals↗
PubMed1980

A histochemical study about the zonal distribution of the galactose-binding protein in rat liver.

1. Dog intestinal alkaline phosphatase (IAP), an asialoglycoprotein, appeared to be a good marker for the histochemical detection of the galactose specific binding protein in cryostat sections of rat liver. 2. Binding of IAP to the receptor is optimal at neutral and slightly alkaline pH values. The binding could be inhibited by galactose and galactose containing sugars, whereas glucose and mannose did not show any effect. In contrast to fetuin itself desialylated fetuin completely inhibited IAP binding. Pretreatment of sections with phospholipase C or with trypsin inhibited IAP binding; collagenase did not show any influence. 3. The presence of the galactose-binding protein showed a distinct zonal distribution. In the area around the central vein (zone 3) the highest IAP binding capacity was found.

Alkaline Phosphatase↗
PubMed1979

A histochemical study about changes in rat liver plasma membrane enzyme activities after galactosamine administration.

In rats changes in plasma membrane enzyme activities due to Gal-N intoxication were studied by enzymehistochemical methods. The bile canalicular 5'-nucleotidase and nucleoside polyphosphatase activities decreased; the sinusoidal 5'-nucleotidase remained unchanged. The bile canalicular leucyl-beta-naphthyl-amidase showed an increase in activity; the alkaline phosphatase activity remained unchanged. In contrast to the spotty necrosis, changes in plasma membrane enzyme activities were seen in all liver cells, suggesting that changes of these activities, occurring after Gal-N treatment, do not correlate with cell death. The conclusion was drawn that the deviations of the enzyme activities might be due to changes in the lipid environment of the enzyme proteins in the membrane. With the exception of alkaline phosphatase, partial hepatectomy caused the same changes in enzyme activities as did Gal-N intoxication. Nevertheless Gal-N administration to partial hepatectomized rats did not lead to hepatic necrosis. Galactose given simultaneously or within two hours after Gal-N prevented both changes in plasma membrane enzyme activities and hepatocellular damage. This suggests an important role of galactolipids and galactoproteins in the plasma membrane alterations.

Adenosine Triphosphatases↗
PubMed1978

A histochemical study about the influence of lytic enzymes on plasma membrane enzyme activities in rat liver and kidney.

1. The effect of lipolytic, glycolytic and proteolytic enzymes on the activities of plasma membrane enzyme activities in rat liver and kidney has been investigated by a pretreatment of tissue sections with the lytic enzymes. 2. The action of the proteolytic enzymes causes a very strong decrease of leucyl-beta-naphthylamidase activity, whereas the activities of ATP-ase, 5'-nucleotidase and alkaline phosphatase show a lesser decrease. This indicates a different membrane anchorage of leucyl-beta-naphthylamidase as compared to that of the phosphatases. 3. Treatment with glycolytic enzymes results in a decrease of 5'-nucleotidase and ATP-ase activity, whereas liver alkaline phosphatase and leucyl-beta-naphthylamidase show an increase in activity. 4. Treatment with phospholipase C gives about the same results. The very strong decrease of 5'-nucleotidase activity indicates a great dependence on phospholipids.

Alkaline Phosphatase↗
PubMed1977

Influence of fixation and buffer treatment on the release of enzymes from the plasma membrane.

1. Pretreatment of frozon cryostat sections with formaldehyde or calcium ions inhibits diffusion of the plasma membrane enzymes 5' nucleotidase, ATP-ase and alkaline phosphatase during incubation. 2. Treatment of fixed sections with different kinds of buffer at 37 degrees C induces diffusion of enzyme activity from the plasma membrane to other sites of the section and into the incubation medium. This buffer influence depends on temperature: at 4 degrees C only a slight diffusion occurs. Addition of phospholipase C, digitonin or taurocholate to the buffer opposes the buffer effect. 3. Pretreatment of frozen cryostat sections with a mixture of equal parts of chloroform and acetone give a good fixation of the plasma membrane enzymes 5'-nucleotidase, ATP-ase, alkaline phosphate and leucyl-beta-naphthylamidase. During this treatment the different kinds of lipids present in the membrane are ex-racted equally. After this fixation buffer treatment does not cause a visible diffusion of enzyme activity in the section. Only a slight diffusion (1 till 7 percent) into the buffer solution takes place. 4. The mentioned treatments open up possibilities to get insight into the membrane anchorage of plasma membrane enzymes.

Adenosine Triphosphatases↗
PubMed1977

Application of enzymehistochemical methods to isolated subcellular fractions and to sucrose-ficoll density gradients. A contribution to the comparison of histochemical and biochemical data.

To compare histochemical and biochemical determinations of enzyme activities, enzymehistochemical procedures are applied to sections of pellets of subcelluar fractions. These investigations are of value to determine the subcellular localization of histochemically demonstrable enzyme activities and to test the homogeneity of an isolated fraction. In homogenating duckling liver a great part of the endothelial cells is not destructed and consequently is found in the nuclear fraction. Kupffer cell lysosomes land in the heavy mitochondrial fraction, whereas hepatocyte lysosomes are chiefly found in the light mitochondrial fraction. beta-Glucuronidase activity shows a preferentially microsomal localization. Application of enzymehistochemical staining reactions to discontinuous gradients and comparison with biochemical data provides additional information about the validity of an enzymehistochemical reaction. In rat liver the tetrazolium reductases show a distinctly dual localization: activity in the mitochondrial band and in microsomal bands. As to their localization in different bands of the gradients non-specific esterases demonstrate a clear pH-dependency.

Acetylglucosaminidase↗
PubMed1976

Enzyme histochemistry as a link between biochemistry and morphology.

The presented paper describes the role of enzyme histochemistry in cell biological investigations. In the first chapter a general discussion has been given about enzyme histochemistry as a connecting link between biochemistry and morphology. The methods available for determination of enzymes in a particular cell or cell compartment have been reviewed. In this respect the characteristics of enzyme histochemistry have been discussed. Furthermore, attention has been paid to the possibilities and limitations of enzyme histochemistry. In chapter two a comparison has been made between histochemically judged and biochemically determined enzyme activities. Some fundamental differences between the biochemical and the histochemical approach in cell biological investigations are dealt with. To correlate histochemically and biochemically determined enzyme activities, a description has been given of the application of histochemical methods on isolated fractions and sucrose-ficoll gradients of these fractions. Several experimental results are described concerning the question whether a relation exists between histochemically and biochemically determined activities of respectively alkaline phosphatase, glucose-6-phosphatase, 5'-nucleotidase and 3ss-hydroxysteroid dehydrogenase. From these results the conclusion could be drawn that in general a good correlation exists between histochemically judged activity per volume (area X thickness) and biochemically determined activity per gram tissue. In chapter three the role of enzymes as markers of cellular particles and as parameters of metabolic pathways is described. Histochemical methods are available for most marker enzymes. Only activities of key enzymes can be regarded as parameters of metabolic pathways. The distribution in sucrose-ficoll gradients of enzymes, regarded as markers of mitochondria, lysosomes, endoplasmic reticulum and plasma membranes has been given. The changes occur ing under different experimental conditions for a number of marker enzymes in rat liver are described. Attention has been given to the contibution of enzyme histochemistry in the study of the heterogeneity of mitochondria, the dual localization of some (lysosomal) enzymes, the complexity of the microsomal fraction, the function of the Golgi apparatus and the heterogeneity and function of plasma membranes. Based on these results and on literature findings the possible role of some marker enzymes in cell metabolism has been discussed. In chapter four problems coherent with species and sex differences in enzyme activities are described. The interpretation of histochemical and biochemical results in view of these differences is discussed. Enzymes characteristic for a given cell type -3ss-hydroxysteroid dehydrogenase in steroid producing cells, ATP-ase in liver plasma membrane surrounding the bile canaliculi - do show less variations between species and sexes than enzymes not directly involved in specialized functions...

Adenosine Triphosphatases↗
PubMed1975

Initial events in radiation-induced atheromatosis I. Activation of lysosomal enzymes.

Local irradiation of the carotid artery of the hypercholesterolemic rabbit with 2000 rd of X-rays gives rise to infiltration of lipid droplets in the intima and media, becoming visible 3 days after the irradiation. At the same time, acid phosphatase and beta-glucuronidase become activated. These enhanced activities are localized in different cells of the arterial wall. Acid phosphatase activity is localized in the intima, while the beta-glucuronidase activation is found preferentially in the media. A functional heterogeneity of the lysosomal content of the different cells is suggested. A model for the development of the radiation-induced atheromatosis is presented.

Acid Phosphatase↗
PubMed1975

Cellular membranes and membrane-bound enzymes in vitamin E deficiency. A histochemical, cytochemical, biochemical, and morphologic study of the liver of the Pekin duckling.

The objective of this investigation was to find out whether vitamin E deficiency, apart from influencing the lipid component of cellular membranes, also influences the protein component. For that purpose a number of membrane-bound enzymes in the liver of the Pekin duckling were histochemically, cytochemically, and biochemically examined. Furthermore, cells, cellular membranes, and protein particles in membranes were morphometrically investigated. Histochemically five membrane-bound enzymes appeared to be stimulated in vitamin E deficiency: 5'-nucleotidase, glucose-6-phosphatase, isocitrate dehydrogenase (NADP), tetrazolium reductase (NADH), and tetrazolium reductase (NADPH). 5'-Nucleotidase and glucose-6-phosphatase were also investigated cytochemically and biochemically. The cytochemical localization of these enzymes was identical in control and vitamin E-deficient ducklings. Biochemically, a stimulation of these two enzymes also could be demonstrated. The increase per milligram of DNA appeared to be largest whereas the increase per milligram of protein, per milligram of phospholipid, and per milligram of RNA was only half of the increase per milligram of DNA. This can be explained by the 30 per cent increase of the cell volume in vitamin E deficiency leading to an increase of protein, phospholipid, and RNA per cell. The thickness of membranes and the diameter of protein particles in membranes were measured in liver parenchymal cells. In vitamin E deficiency the thickness of the outer mitochondrial membrane and the diameter of protein particles in this membrane were smaller whereas the thickness of the endoplasmic reticular membrane was larger. The increase of the activities of mitochondrial and microsomal enzymes and the decrease of the thickness of the outer mitochondrial membrane and of its protein particles are interpreted to be the result of the influence of free radicals on membranes with electron transport functions. The increase of 5'-nucleotidase activity in the plasma membrane is likely to have a different cause; it may be related to the transport of nucleotides across this membrane.

Animals↗
PubMed1975

Correlation between serum alkaline phosphatase and localization of alkaline phosphatase in the liver.

1. A good correlation exists between histochemically judged and biochemically determined activity of alkaline phosphatase in the liver. 2. Normal localization of alkaline phosphatase in the human differs from that in the rat. 3. In Wistar rats normal localization is: low or no activity in bile canaliculi preferently in the peripheral part of the lobule. 4. Normal localization in the human is: moderate to strong activity in the sinusoidal wall, in the central and peripheral part of the lobule. 5. A relation exists between histochemical localization and serum value of alkaline phosphatase in rat and in human. 6. Raised activities at localizations where "normally" no activity is present, e. g. bile canaliculi in human, sinusoidal wall in rat, do correlate the best with raised serum activities.

Alkaline Phosphatase↗