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Biomedical subjects

M Borgers

Publications and source records attributed to M Borgers.

At least 217 records · Page 12Linked to original sources
PubMed1976

Early myocardial ischaemia: evaluation of the histochemical haematoxylin-basic fuchsin-picric acid (HBFP) staining technique.

A series of experiments, carried out to evaluate the histochemical method for the morphological diagnosis of early stages of myocardial ischaemis (HBFP) is reported. The experiments were performed on dog hearts in which ischaemia was induced by coronary artery ligation for different periods of time. The original procedure or modifications of the HBFP-technique, including different staining, rinsing, and differentiation times, the use of different commercial brands of chemicals and preparatory changes of routine histological procedures such as fixation, embedding, cutting, and mounting, did not give satisfactory results. False positive and negative staining was frequent. Very equivocal results were obtained on serial sections of ischaemic tissue samples. Therefore this method was regarded as unreliable and non-reproducible.

Animals↗
PubMed1976

Effects of levamisole on the ultrastructure of mitochondria in the liver of Beagle dogs.

Purebred Beagle dogs were treated daily for 6 days with levamisole in oral doses of 10 mg/kg body weight. Liver biopsies taken before and after treatment showed no ultrastructural differences. Intramitochondrial paracrystalline inclusions before, as well as after, the drug administration were rare. Other minor abnormalities, in a few mitochondria, were as frequent before as after the drug treatment.

Animals↗
PubMed1976

The effects of methyl (5-(2-thienylcarbonyl)-1H-benzimidazol-2-yl) carbamate, (R 17934; NSC 238159), a new synthetic antitumoral drug interfering with microtubules, on mammalian cells cultured in vitro.

Ultrastructural investigations on mammalian cells cultured in vitro show that R 17934, a new synthetic anticancer drug, interferes with the structure and function of microtubules, both in interphase and mitotic cells. The activity of this compound in a wide range of experimental tumor systems can thus be explained partly as a direct antimitotic effect and partly as the disintegration of the normal subcellular organization of the nondividing cells. Preliminary investigations in experimental animals show that malignant cells are more susceptible to the antimicrotubular effect of R 17934 than are the nonmalignant cells of the host.

Antineoplastic Agents↗
PubMed1975

The inhibition of alkaline phosphatase by L-p-bromotetramisole.

A levamisole analogue, the L-p-bromotetramisole is introduced as a potent inhibitor of non-specific alkaline phosphatase. Complete inhibition is achieved cytochemically at a concentration of 0.1 mM in various rat tissues except the intestine, which is not affected. The D-p-bromotetramisole does not influence the alkaline phosphatase activities. Since no effect of the inhibitor is seen on the activities of specific phosphatases, this drug is recommended also as an additive for specific phosphatase media in order to yield the specific activity only.

Adenosine Triphosphatases↗
PubMed1975

The development of alkaline phosphatase in trichinous muscle.

The development of alkaline phosphatase during invasion and encystment of Trichinella spiralis in rat skeletal muscle fibres was studied at the ultrastructural level. On day 14 after infection, the enzymatic activity is found in proliferating parts of the T-tubular system and in parts of the plasmalemma. In cells, in which a strong hyperplasia of this system is noted. AlPase is present in the abundant network of stratified and concentric membranes from which a large number of pinocytic vesicles arise. From day 50 till 1 year after infection the enzyme activity was invariably present in the matrix surrounding the larvae and was confined to the enormous amounts of cytoplasmic membranes. The possible functional significance of this enzyme in the matrix, in view of its peculiar localization in the immediate vicinity of the parasite, is discussed. In the presence of 0.1 mM of the levamisole analogue, compound R 30402, which is a stereospecific inhibitor of AlPase, the activity is completely lost.

Alkaline Phosphatase↗
PubMed1975

The separation and characterization of liver plasma membrane fragments circulating in the blood of patients with cholestasis.

Investigations on the high molecular weight isozyme of alkaline phosphatase (R type of AP), which is typically found in the serum of patients with cholestasis, have revealed that AP of the R type corresponds to the conventional liver AP which is attached to vesicular material. The isolation of these vesicles by Sepharose gel filtration is described. Several features were found to be characteristic for these vesicles: 1. The presence of the following enzymes known to be membrane bound: alkaline phosphatase (AP), 5FEET-NUCLEOTIDASE, L-leucyl-beta-naphthylamidase (LAP), and gamma-glutamyl transpeptidase (gamma-GT). 2. The absence of the following enzymes known not to be present on cell membranes: glutamic pyruvic transaminase (SGPT), glutamic oxalacetic transaminase (SGOT), lactate dehydrogenase (LDH), and acid phosphatase. 3. The typical ultrastructural appearance and the cytochemical visualization of alkaline phosphatase and 5feet-nucleotidase. It is concluded that the vesicles correspond to fragments of the liver cell membranes that appear and continue to circulate in the blood of patients with cholestasis.

Alkaline Phosphatase↗
PubMed1975

Dissociation of clot retraction from platelet granule fusion and degranulation: an ultrastructural study of Reptilase-human platelet-rich plasma clots.

Human platelet-rich plasma clots, formed with Reptilase, do not retract. Electron microscopy of such a clot reveals platelets of normal shape and ultrastructural features surrounded by fibrin. When ADP is added before Reptilase, the clot strongly retracts. A sequential ultrastructural study of this process shows that, before visible fibrin formation, the platelets form small clusters and show shape change, granule centralization and pseudopod formation. Upon immobilization of the platelets by fibrin, the pseudopods develop into large cytoplasmatic protrusions, which allow cell contact. During the retraction process, the platelet granules remain intact; some granule fusion only becomes apparent in fully retracted clots. When Thrombofax is added to platelet-rich plasma before Reptilase, the clots formed also retract. With this aggregation inducer, granule fusion occurs earlier and in more platelets. Platelet pseudopod enlargement and fibrin concentration around the platelet mass are similar to that in ADP-treated samples. Inhibitors of granule fusion and secretion (suprofen, indomethacin) do not modify ADP-Reptilase nor Thrombofax-Reptilase clot retraction but reduce the incidence of granule fusion in Thrombofax-Reptilase clots. Retraction of Thrombofax-Reptilase clots is unaffected by concentrations of apyrase which completely block ADP-Reptilase clot retraction. Prostaglandin E1, papaverine and amitryptiline inhibit both ADP-and Thrombofax-Reptilase clot retraction, platelet pseudopod formation and cell-to-cell adhesion. These findings suggest that interaction of fibrin with the mass of fused granules (granulomere) or platelet secretion are not responsible for clot retraction. Rather, contraction around adhesion sites formed by cytoplasmic protrusions from adjacent platelets would seem to be involved.

Adenosine Diphosphate↗
PubMed1975

Scanning electron microscopy of Candida albicans after in vitro treatment with miconazole.

A study was made on the in vitro action of the antimycotic miconazole on Candida albicans yeast cells with scanning electron microscopy, and the effects were compared with those seen on the yeast cells by means of transmission electron microscopy. It was found that cells exposed to fungistatic and minimal fungicidal doses of miconazole (10(-7) M and 10(-6) M) presented rough surfaces and had multiple, desoriented buds and bud scars. Whereas in control cultures the cells were well separated, the treated ones formed small clusters of interconnected cells. After exposure to a fungicidal concentration (10(-4) M) of the drug, most of the remaining cells showed smooth surfaces and were covered with numerous vesicular structures probably representing cytoplasmic remnants derived from broken cells. This has been substantiated by the presence of abundant fragments of cell walls and confirmed by examination of similarly treated cultures in the transmission electron microscope. Moreover, the cells with an apparently intact surface when examined with scanning electron microscopy were shown with transmission electron microscopical examination to be completely necrotic inside.

Candida albicans↗
PubMed1975

Enzyme cytochemistry of Candida albicans.

The application of a new preparation method for demonstrating the activities of hydrolytic and oxidative enzymes in Candida albicans is reported. The problem of inadequate penetration of fixatives into yeast cells has been solved by sectioning solidified pellets of the cells in the presence of glutaraldehyde, a procedure that yields a fairly well preserved ultrastructure and sufficient enzyme activities. The subcellular distribution of most specific and nonspecific phosphatases and of peroxidases is at variance with that found in mammalian cells. The activities toward beta-glycerophosphate, p-nitrophenylphosphate, adenosine triphosphate, adenosine monophosphate, thiamine pyrophosphate and glucose 6-phosphate are almost exclusively confined to the central vacuolar apparatus. Oxidative and peroxidative activities are demonstrated only in mitochondria. Specific marker enzymes for endoplasmic reticulum, plasmalemma, Golgi apparatus and peroxisomes in C. albicans are not found. The possible function of the various subcellular organelles in relation to their enzymatic content is discussed.

Acid Phosphatase↗
PubMed1975

The formation of annulated lamellae induced by the disintegration of microtubules.

Investigations with different 'antitubulins' have shown that different cell types in culture response to prolonged treatment with the formation of annulated lamellae. These annulated lamellae are possibly derived from previously accumulated smooth endoplasmic profiles. A hypothetical explanation would be that annulated lamellae (and the nuclear membrane) are sites of tubulin synthesis or microtubular polymerization. Their appearance after induced microtubule disintegration could then be viewed upon as a reactive hyperproduction of such sites.

Cell Line↗
PubMed1975

A simple polychrome stain for conventionally fixed Epon-embedded tissues.

The described technique, based upon a one-step Mallory-Heidenhain stain, can be applied as a routine stain for glutaraldehyde or OsO4 fixed, Epon embedded tissues of various organs. The technique consists of a short treatment of the sections with H2O2, a nuclear staining with celestine blue B and a final staining in a modified Cason's solution. The different tissue and cell components are displayed as follows: dark brown nuclei, yellow cytoplasm, red collagen fibers and blue elastic fibers. Intracytoplasmic components as glycogen and mucus are stained respectively blue and violet, whereas other inclusions such as leucocyte granules are colored orange to red.

Animals↗
PubMed1975

Ultrastructural changes in Ascaris suum intestine after mebendazole treatment in vivo.

The effect of in vivo treatment with mebendazole on the ultrastructural morphology of Ascaris suum intestine was investigated. Pigs, infected with A. suum, were fed ad libitum a medicated food containing mebendazole at a concentration of 30 ppm. Control and treated animals were killed 6, 9, 15, and 24 hr after the onset of feeding. The parasites were quickly collected from the pig intestinal tract and prepared for ultrastructural and cytochemical examination. Absence of secretory granules in the terminal web, accumulation of secretory granules in the Golgi region, formation of autophagic vacuoles in the apical cell part, and loss of glycogen were the characteristic changes observed after 6 and 9 hr of treatment. Degenerative changes were very pronounced after 15 and 24 hr and involved almost the entire cytoplasm. Microvilli were decreased in number and appeared swollen in the majority of absorptive cells. Some more severely altered cells were completely devoid of microvilli. Cytochemistry revealed that the accumulated secretory granules in the Golgi area contained glycoproteins or polysaccharides. Microvilli, lysosomes, and Golgi apparatus were reactive for acid phosphatase in the control intestinal cells. After treatment, the enzyme activity was localized in numerous autophagic vacuoles, whereas the secretory granules remained unstained. The acid phosphatase activity in the microvilli decreased or was completely absent. The possible significance of these modifications in view of mebendazole's anthelmintic activity is discussed.

Acid Phosphatase↗
PubMed1975

Influence of the anthelmintic mebendazole on microtubules and intracellular organelle movement in nematode intestinal cells.

The ultrastructural changes in the intestines of Ascaris suum and Syngamus trachea, induced by in vivo treatment of the hosts with the anthelmintic mebendazole, are reported. The primary site of drug action seemed to be the organelles involved in the secretory mechanism of the intestinal cells. The block in the transport of secretory granules and in the movement of other subcellular organelles coincided clearly with the disappearance of cytoplasmic microtubules. On the other hand, the microtubular system of the host cells was unaffected by the treatment. Degenerative changes in the intestinal cells of the parasites observed afterwards were correlated with the primary deteriorative effect of the drug on cytoplasmic microtubules.

Acid Phosphatase↗