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PubMed1994

Changes in rabbit corneal epithelial membrane permeability caused by locally applied Pseudomonas aeruginosa cytotoxin: a microfluorometric examination in vivo.

The effects of a pore-forming protein from Pseudomonas aeruginosa on the rabbit cornea were tested in vivo by measuring intraepithelial carboxyfluorescein accumulation. Carboxyfluorescein diacetate and subsequently the P. aeruginosa cytotoxin were applied by means of contact lenses with a spherical cavity on the concave surface. This allowed the application of defined concentrations of carboxyfluorescein diacetate and cytotoxin on a defined area of the corneal epithelium. Starting at 0.5 microM, cytotoxin increased the epithelial cell membrane permeability for the intracellular carboxyfluorescein within 1 min. At higher concentrations cells were shed from the epithelium. Corresponding morphological changes of the cellular structure of the corneal epithelium were observed and documented by fluorescence photomicrography. The healing process of toxified corneal epithelium appeared to be complete within 3 days. The data presented here indicate the possible role of cytotoxin-induced changes in epithelial permeability in P. aeruginosa infections. In this context, the role of soft contact lenses as a possible cytotoxin reservoir is discussed.

ADP Ribose Transferases↗
PubMed1996

Preliminary study of electrocautery smoke particles produced in vitro and during laparoscopic procedures.

BACKGROUND: The objective of this preliminary study was to describe the particles contained in cautery smoke produced during five laparoscopic procedures and verify the collection method during three laboratory experiments on ex vivo animal tissue. METHODS: A cascade impactor collected the smoke according to particle size, and particle weights were calculated on an electronic microbalance. Electron microscopic analysis and energy dispersive X-ray evaluation were used to determine particle morphology and elemental composition. RESULTS: The particles, distributed according to size on the seven rotating trays of the impactor, had diameters ranging from 0.05 to >25 micro m, with most being 0.1-1 micro m. In vitro experiments yielded more particles, especially larger (>5 micro m) ones, than the surgical procedures, because the cauterized specimens could be placed much closer to the cascade impactor in the laboratory environment, eliminating most obstacles to particle recovery. In the laparoscopic surgery patients, larger particles, because of their physical properties, were more likely to remain trapped in the abdomen or to drop off in the collection apparatus. Uniformly, two populations of particles were demonstrated--either large, irregular fragments (2-25 micro m) rich in carbon and oxygen, suggesting structural cellular components, or small homogeneous spheres (0.1-0.5 micro m) composed of sodium, magnesium, calcium, and potassium salts. CONCLUSIONS: This study demonstrates the presence of breathable aerosols and cell-size fragments in the cautery smoke produced during laparoscopic procedures. Their exact chemical composition and potential adverse effects for patients and personnel are not known.

Cautery↗
PubMed1994

Cytoskeletal involvement in neuronal learning: a review.

This paper introduces the ideas of neural networks in the context of currently recognized cellular structures within neurons. Neural network models and paradigms require adaptation of synapses for learning to occur in the network. Some models of learning paradigms require information to move from axon to dendrite. This motivated us to examine the possibility of intracellular signaling to mediate such signals. The cytoskeleton forms a substrate for intracellular signaling via material transport and other putative mechanisms. Furthermore, many experimental results suggest a link between the cytoskeleton and cognitive processing. In this paper we review research on intracellular signaling in the context of neural network learning.

Animals↗
PubMed1984

Effects of progestins and antiprogestins on mitochondria in uterine glandular cells in the rat. A quantitative investigation.

The administration of progesterone to ovariectomized rats induces an increase in the volume density (Vv) of the mitochondria and the appearance of giant mitochondria in the uterine glandular cells. This experimental model, including a stereological analysis, allowed us to investigate and quantify a direct effect of progesterone on a well-defined cellular structure without the intervention of estrogen in a priming phase. Synthetic compounds, promegestone, gestrinone and RU 38486, were tested in this model either in place of progesterone or simultaneously with progesterone. The potent progestomimetic activity of promegestone was confirmed by the proliferation of giant mitochondria and a high Vv value for the mitochondria, the two other compounds being inactive even at higher doses. At lower doses, gestrinone and RU 38486 partially inhibit the action of progesterone and at higher doses they both show a complete antagonist effect by preventing the development of the mitochondria.

Animals↗
PubMed1987

Glycolysis--new concepts in an old pathway.

A survey of the existing data on the interactions of glycolytic enzymes with the cellular structure in mammalian tissues has substantiated the occurrence of an extensive degree of such associations in all tissues and during all stages of development. Furthermore, a considerable specificity was evident between the individual multiple forms of the enzymes in relation to these associations. In reviewing these data, a model has been developed which proposes that the glycolytic sequence is best described as consisting of a number of segments in vivo, each segment formed by a cluster of isozymes, many of which can interact with the actin containing filaments of the cytomatrix. The novel features of this segmentation and compartmentation have been described, and evidence has been provided that these phenomena collectively play a key role in meeting the different types of energy requirement in the cytoplasm of divergent cell types, with the wide selection of isozymes in this system offering the potential for increased flexibility and control in this important area of metabolism.

Animals↗
PubMed1996

The effects of thromboxane A2 synthetase inhibitor (OKY-046) on complete hepatic ischemia in rats with obstructive jaundice.

The effects of OKY-046, a thromboxane A2 synthetase inhibitor, on hepatic dysfunction produced by liver cell ischemia were studied in an experimental model of rats with obstructive jaundice. The experiments were performed 7 days after the rats underwent bile duct ligation. Warm total ischemia of the liver was induced by Pringle's method over a 20-min period and the animals were divided into two groups according to whether or not OKY-046 was administered. The reperfusion time was 30 min in each group. OKY-046 was administered via the femoral vein at a rate of 100 micrograms/kg per min from 15 min before the blockade to the end of the experiment. The level of ATP in the liver tissue of the OKY-046 group was elevated slightly, but not significantly, compared to that of the control group. The ratio TXB2/6-keto PGF1 alpha in the liver tissue was lower in the OKY-046 group than in the control group, and significant differences were found between the two groups in the water content of the liver and the mitochondrial score as examined by transmission electron microscopy. Thus, it was observed that an improvement in the balance of TXA2 and PGI2 associated with OKY-046 administration proctected the cellular structure of the mitochondria in the rat liver.

6-Ketoprostaglandin F1 alpha↗
PubMed1976

Gap junctions between astrocytes during growth and differentiation in organ culture systems.

Fetal rat neocortex maintained in organ culture systems with the use of sponge foam matrices and millipore filter platforms undergoes growth and cytodifferentiation along classical neuronal and glial lines up to 36 days in vitro (DIV). Astrocytic differentiation is characterized by accumulation of 80-90 A glial filaments in the cell bodies and processes of astrocytes. Gap or nexus junctions closely resembling those formed in mammalian brain in situ are identified by 15 DIV. By 36 DIV, interastrocytic gap junctions are numerous and frequently join extensive lengths of adjacent glial plasma membranes. The results suggest that these organ culture systems may provide a favorable environment for the study of cellular structure and function of coupled neuroglia.

Animals↗
PubMed1976

Prevalence and pathology of Hepatojarakus bandicoti Sood et Parshad, 1973 (Trichostrongylidae:Nematoda) in natural infections of rodents.

The prevalence and pathological changes in the liver and biliary system of field rodents due to Hepatojarakus bandicoti Sood et Parshad, 1973 have been worked out. Higher infection rates occurred in Tatera indica and Bandicota bengalensis than in other field rats and mice. In heavy infections, the liver became grossly enlarged, hard and pale, and showed the presence of white scars on its surface and in the parenchyma. White nodules are commonly seen on the bile ducts due to heavy infections. Histologically the liver showed a changed lobular structure, cellular infiltrations, pycnotic nuclei of the hepatic cells with deposition of haemosidirin granules. Hypermorphosis of the biliary epithelium with its denudation, resulting from the creeping action of the worm seemed to be a common tissue response.

Animals↗
PubMed1983

The correlation between tissue differentiation and production of mammary tumor virus (MTV) in transplanted murine mammary tumors. Electron microscopic observations.

The spontaneous mammary tumors of the NMRI mouse are well developed microcystic adenocarcinomas. Serial isologous transplantation of the tumors results in nearly complete dedifferentiation to a solid tumor, in which only electron-microscopically rudimentary acinus-like microlumina can be observed. The adenocarcinomas produce A and B particles in abundance, with the A particles appearing intracellularly in the adluminal cytoplasmic regions of the epithelial cells in association with typical cellular structures and the B particles being restricted to closed extracellular compartments such as vacuoles or acini alone. The loss of alveolar organization in the solid tumors is followed by an almost complete reduction in mature B particles, while A particles are still regularly observed and appear to be less reduced in number. This suggests that the production of extracellular B particles is dependent upon the secretory activity of the tumor cells and that in nonsecreting cells it is predominantly a late step in virus release that is inhibited, not the synthesis of intracellular precursors.

Adenocarcinoma↗
PubMed1977

The action of sensitized lymphocytes on the corneal endothelium of rabbits.

A host versus graft reaction is induced by the injection of sensitized lymphocytes into the anterior chamber of rabbit eyes. The reaction of these lymphocytes against the corneal endothelium is studied with S.E.M. and T.E.M. On the first and second days the transformation of lymphocytes into active cells with uropods is observed. These immunologic cells destroy the endothelium, but the endothelial cells regenerate quickly. On the sixth day there appear macrophages coming from the host, indicating that the lesions are being cleaned. These experiments present a good model for the study of the interaction between immunologic cells and an organized cellular structure.

Animals↗
PubMed1994

Taurine, amino acid transmitters, and related molecules in the retina of the Australian lungfish Neoceratodus forsteri: a light-microscopic immunocytochemical and electron-microscopic study.

The morphology of the retina of the Australian lungfish Neoceratodus forsteri was investigated by means of light- and electron microscopy, whilst immunocytochemical studies were performed to determine the cellular distributions of the major amino acid neurotransmitters and other amino acids. The distributions of glycine and GABA were similar to those previously described for teleost, amphibian and mammalian retinae. Labelling was abundant in amacrine cells, whilst GABA was also present in one layer of horizontal cells and some bipolar cells. Taurine was present in both rods and cones, but, unlike the mammalian or avian retina, was absent from other cellular structures, including glial elements. Unexpectedly, the photoreceptor terminals lacked an apparent content of the excitatory amino acid transmitter glutamate. The glutamate that was present in the rods and cones occupied a crescentic arc corresponding to the location of glycogen-rich paraboloids. Asparagine was also present in rods, albeit in the modified mitochondria that formed the elipsoids of the rod inner segments. Arginine, the precursor for formation of nitric oxide, was present in glial cells, and in the paraboloids of both rods and cones.

Animals↗
PubMed1977

Protease activities during preparation and handling of nuclear particles containing hnRNA.

Conditions were devised to avoid protease activity during the preparation and the subsequent handling of nuclear particles containing hnRNA. During all the steps of preparation of rat liver particles, the presence of phenylmethyl sulfonyl fluoride (PMSF) was required for the reproducibility of the results. It probably inhibited the cellular serine proteases before the separation of the particles from the other cellular structures. Protease activity was detected in the rat liver particles. The enzyme(s) preferentially hydrolyzed a few particle polypeptides. It was not inhibited by PMSF, nor by two trypsin and chymotrypsin-like protease inhibitors, nor by iodoacetamide, but was inhibited by sodium bisulfite and para-hydroxymercury benzoate (PHMB). PHMB was preferred above bisulfite because it could be used at lower concentration. It proved useful when particles were to be incubated at 37 degrees C. A protease hydrolysing the same polypeptides as the liver enzyme was also detected in rat brain particles. However, its activity was much lower in this tissue and the presence of protease inhibitors was not absolutely required under the standard conditions of preparation and handling of brain particles.

Animals↗
PubMed1986

Histochemistry of glycosaminoglycans in cartilage ground substance. Alcian-blue staining and lectin-binding affinities in semithin Epon sections.

The critical-electrolyte-concentration staining method using Alcian blue (AB) was applied to etched semithin Epon-embedded sections. The distribution of various glycosaminoglycans (GAGs) was studied in hyaline, elastic, cellular and fibrous cartilage obtained from humans and rodents. The staining patterns in semithin sections were found to correspond to those obtained using paraffin-embedded material. Lectin histochemistry was performed on consecutive sections. The following peroxidase-labelled lectins were used: Ricinus communis A I, Arachis hypogaea, Ulex europaeus A I, Triticum vulgaris, Helix pomatia, Limax flavus, and concanavalin A. The lectin-binding capacity of cartilaginous ground substance was found to be low, as was expected on account of the few free sugar residues of GAGs. Chondroitin sulphate, the most widely distributed GAG, did not exhibit lectin staining. The lectin-binding sites (positive staining for all lectins tested except H. pomatia) observed corresponded to areas positive for keratan sulphate, as shown by AB staining in preceding or following sections. The pronounced lectin binding seen in cellular structures and the inner territorial matrix regions is considered to be due to higher concentrations of oligosaccharides involved in the metabolism of GAGs.

Alcian Blue↗
PubMed1978

Cobalt thiocyanate as a stain for basic proteins and other organic bases on thin sections.

Thin sections in mouse mast cells and thymic cells are stained with cobalt thiocyanate a compound known to form insoluble complexes with organic bases. Chromatin, nucleolus, ribosomes and mast cell granules are contrasted. Different blockade reactions and enzymatic digestions indicate the staining corresponds to the basic protein amino-groups. The silver methenamine reaction stains the same cellular structures. However, the specificity control reactions show the staining mainly corresponds to protein sulphydryle groups and in a lesser extent to aldehyde and polyanions.

Animals↗
PubMed1976

Histochemical findings in the rat gastric mucosa during starvation.

The influence of starving on the activity of enzymes of the rat gastric mucosa was investigated by selected histochemical methods. Beside the conventional methods of enzymatic histochemistry the technique of semipermeable membranes was used in the proof of lysosomal enzymes. Dehydrogenases were proved in aqueous and also in gel media with PMS. During the starvation in the parietal cells a marked increase took place in the activity of acid phosphatase, E-600 resistant esterase, less in beta-glucuronidase. High activity of the lysosomal enzymes in macrophages did not change during starvation. Nor did any changes took place in the activity of alkaline phosphatase in the endothelium of the capillaries. The chief cells in the control and starving animals, in contrast to the human gastric mucosa, did not contain any non-specific esterase. Concerning dehydrogenases, parietal cells with a different activity of these enzymes were observed both in starved and control animals. In the rat gastric mucosa starving induced changes in the activity of the enzymes which mark important organelles of the cells. Thus it is possible to consider the observed histochemical changes as a functional manifestation of morphological damage of cellular structures which are affected during starvation.

Acetylglucosaminidase↗
PubMed1988

Quantitative enzyme histochemistry in the brain.

Two main groups of quantitative methods are used in the brain to relate enzymatic processes to cellular structures, i.e. the methods of microchemistry and microscopic histochemistry. Microchemistry tries to quantify enzyme activities in very small brain regions by miniaturizing biochemical methods, whereas microscopic histochemistry applies staining procedures to tissue sections, preserving the structural relationship that is present in situ and giving topological information on the distribution of enzymes which is indispensable in structural heterogeneous tissue as is the brain. The present review deals preferentially with microscopic methods and, in particular, with scanning microphotometry (image plane scanning). Using this technique two measuring procedures can be applied for the quantification of enzyme activities, i.e. end-point and kinetic (continuous monitoring) measurements which are described in detail. Methods for the microphotometric demonstration of certain important dehydrogenases (isocitrate dehydrogenases, succinate dehydrogenase, NAD-linked malate dehydrogenase, glutamate dehydrogenase and glycerol 3-phosphate dehydrogenase), of cytochrome c oxidase, hexokinase and acetylcholinesterase are presented. These methods were adapted for giving optimal demonstration of enzyme activities in the rat hippocampus. The examples are given to illustrate the aptitude and possibilities of this technique in the quantification of enzymes in the complex matrix of the brain.

Brain↗
PubMed1979

A quantitative histochemical technique for the characterisation of alpha-glucosidases in the brush-border membrane of rat jejunum.

A quantitative histochemical method to determine the Km and Vmax of alpha-glucosidases in the intestinal epithelium without disruption of the cellular structure is described. 2-Naphthyl-alpha-D-glucoside was used as substrate and hexazonium-p-rosaniline as coupling agent. Using a Leitz MPV2 microdensitometer and a field measuring 4 X 4 micrometers, and reading the test samples against a blank focused on the lamina propria, we observed that the intensity of the colour was a linear function of both the incubation time up to 20 min, and the thickness of the slice up to 20 micrometers. The ratio between the extinction at the absorption maximum and at a second wave-length was constant, whatever the intensity of the colour. By determining the relationship between the extinction and the substrate concentration under standard conditions (slice thickness of of 10 micrometers and incubation time of 10 min), we obtained a saturation curve described by a Km of 0.68 +/- 0.038 mM and a Vmax of 1.41 +/- 0.039 A lambda 480 . 10(-2) . micrometers-1 . min-1. When the hydrolysis of the same substrate by a homogenate of jejunal mucosa was examined biochemically under comparable conditions, a Km of 0.64 +/- 0.012 mM and a Vmax of 57.3 +/- 0.70 mU/mg protein were obtained. When the natural substrate, sucrose, was used in the biochemical study, a Km of 15 +/- 3.5 mM and a Vmax of 149 +/- 24.7 mU/mg protein were obtained. These experiments demonstrate that the kinetic constants of enzyme reactions can be assessed with equal accuracy on histochemical sections as in tissue homogenates.

Animals↗
PubMed1979

Resolution of a gold latensification-elon ascorbic acid developer for Ilford L4 emulsion.

The electron-microscopical autoradiographical resolution of a gold latensification-elon ascorbic acid (GEA) developer for Ilford L4 emulsion was determined experimentally, using radioactive line sources of tritiated albumin (Heijnen and Geuze, 1977). For sections with a thickness of 62 nm (SD +/- 11), which were covered with a carbon layer about 5 nm thick and a slightly overlapping monolayer of L4 silver bromide crystals, the measured half-distance (HD) of resolution was 115 nm. This improvement in resolution, the high efficiency of the GEA developer for L4 emulsion (Wisse and Tates, 1968), and the excellent visibility of the cellular structures under the small silver grains, mean that the L4-GEA combination deserves preverence as a method for quantitative electron-microscopical autoradiography.

Ascorbic Acid↗