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Query: UMLS:C0432222 (SEM)
 47,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Colloidal gold may be conjugated to a wide variety of macromolecules, provides a versatile system for immunocytochemical studies by various types of microscopy (light and fluorescent microscopy, scanning (SEM) and transmission (TEM) electron microscopy), and is significantly contributing to the development of SEM immunocytochemistry as a routine analytical procedure. A comprehensive overview has been compiled of the literature on SEM bioapplications of colloidal gold. This is illustrated through a selected series of studies focussing on a) cell surface receptor-ligand interactions; b) expression of cell surface lectin-binding sites; c) surface distribution of extracellular matrix components; and d) visualization of gold-labelled cytoskeletal elements with emphasis on the use of backscattered electron imaging as a powerful analytical adjunct in the development of SEM immunocytochemistry.
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PMID:Colloidal gold--a powerful tool in scanning electron microscope immunocytochemistry: an overview of bioapplications. 329 62

The half-lives for coagulation factors in the healthy newborn infant are not known and may be different than for the adult. We measured the half-life for fetal sheep fibrinogen and compared it to the half-life of adult sheep fibrinogen. Fibrinogen was purified from adult and fetal sheep plasma and radiolabeled with either 125I or 131I. The half-lives for these fibrinogens were determined in the adult sheep and newborn lamb. In addition, the fetal and adult sheep fibrinogens were compared by reptilase time, thrombin clotting time, sialic acid content, and the behavior of the N-glycans derived from these fibrinogens on the immobilized lectin, Sepharose-concanavalin A. Finally, the in vivo response of coinjected radiolabeled fibrinogens to increasing doses of infused thrombin was determined. The fetal sheep fibrinogen differed from the adult as indicated by a prolonged reptilase time and an increased sialic acid content (fetal: 10-11 residues/340 Kd versus adult: 8-9 residues/340 Kd). The latter was also reflected in differing chromatographic profiles for the N-glycans on Sepharose-concanavalin A. The half-lives for both the adult and fetal fibrinogen were significantly more rapid in the newborn lamb (fetal: 47 +/- 2.0 h; adult: 46 +/- 2.4 h, mean +/- SEM) than in the adult (fetal: 116 +/- 6.5 h; adult: 121 +/- 6.9 h). Finally, the adult and fetal sheep fibrinogen responded to thrombin in an identical fashion in the intact animal. In summary, both adult and fetal fibrinogen have faster half-lives in the lamb compared tot he adult, despite a higher sialic acid content for the fetal fibrinogen.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Fibrinogen has a rapid turnover in the healthy newborn lamb. 335 68

Somatomedin and bromocriptine levels were measured before and after 3 months of bromocriptine treatment (5 mg/day) in the sera of 16 tall adolescents with excessive adult height prediction. Somatomedins were measured by RIA for somatomedin C and IgFII and by measuring thymidine incorporation into human lectin-activated lymphocytes. Mean +/- SEM levels of bromocriptine after three months of treatment were 0.61 +/- 0.08 ng/ml. No changes in radioimmunoassayable somatomedin C were observed after bromocriptine intake respectively 1.34 +/- 0.17 U/ml before and 1.4 +/- 0.01 U/ml during treatment. On the opposite a significant decrease of thymidine activity (p less than 0.002) from 1.45 +/- 0.17 U/ml to 1.12 +/- 0.19 U/ml was observed. No changes of IgFII levels were observed in the sera of the 8 patients where they were measured. In order to test a possible direct effect of bromocriptine on peripheral tissues bromocriptine mesylate was added in somatomedin bioassays. Inhibitory effect of bromocriptine in vitro is seen at higher levels (1 microM) compared to the circulating one (1 nM). This study demonstrates that the major effect of bromocriptine which is the acceleration of bone maturation is not related to changes in somatomedin C.
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PMID:Effect of bromocriptine treatment on circulating somatomedins in tall adolescents. 395 65

Endothelia lining the 2 surfaces (arterial and ventricular) of the posterior cusp of aortic valves from normocholesterolemic, New Zealand white rabbits were found to display pleomorphic surface features characterized by differences in cellular shape and orientation to the direction of blood flow, microappendage populations (microvilli and blebs), nuclear contours and the surface reactions of cationic dyes (RR, AB) and peroxidase-conjugated lectins (Con A, Limulin, WGA). With the aid of SEM and TEM, the cells lining the arterial surfaces appeared relatively smooth and flattened with a moderate to heavy reaction of the carbohydrate cell coat at the blood interface. By contrast, the contours of the endothelia lining the ventricular surfaces were noticeably raised with numerous plasmalemmal microappendages and only a moderate dye/lectin reaction. Observations of similar endothelial populations from diet-induced, hypercholesterolemic rabbits (500 mg/dl) revealed a variety of dramatic changes in the cells lining the arterial surfaces of the valvular cusps. No severe changes were observed in the endothelia of the ventricular surfaces. Such findings are suggestive further of the importance of the interaction between the environment and the endothelial cell coat as influencing factors in the onset of intramural lipid infiltration.
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PMID:Surface responses of aortic valve endothelia from diet-induced, hypercholesterolemic rabbits. 399 84

Differential localization of glycoconjugates was detected on microvilli and microridges of the intact cell surface of frog pronephric tumor cells in tissue culture. Alcian blue and Alcian blue/PAS staining showed a heavy concentration of dye limited to the unique short microvilli and extensive microridges of the tumor cells as previously seen with SEM (Tweedell and Williams 1976). Staining was absent or greatly reduced on microvilli of the normal pronephric cell surface. Previous exposure of each kind of cells to neuraminidase or extraction by mild hydrolysis removed the active staining sites but Alcian blue uptake was unaffected by prior digestion with testicular hyaluronidase. Fluorescein isothiocyanate (FITC) bound wheat germ agglutinin (WGA) produced a similar pattern of fluorescence on the microvilli of the tumor cells and a limited distribution on the normal cells. Digestion with neuraminidase preferentially removed but did not completely eliminate the surface binding of WGA on both the normal and tumor cells. Exposure of tumor cell monolayers to FITC bound limulin, a lectin specific for sialic acid, also produced an intense surface fluorescence on the microvilli and ridges of tumor cells. Prior treatment with neuraminidase prevented the surface fluorescence but not internal binding. Normal pronephric cells gave sparse surface fluorescence but extensive internal binding. Each procedure indicates a preferential localization of complex carbohydrates, including sialic acid, on the unique microvilli of the tumor cells. Concurrent assays for sialic acid recovered from the tumor cells indicated that lectin bound surface sialic acid was removable with neuraminidase.
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PMID:Localization of glycoconjugates on the surfaces of pronephric tumor cells in vitro. 618 38

The effects of treatment with varying doses of abrin, a D-galactose binding lectin, on DNA an protein synthesis of normal and Epstein Barr Virus transformed lymphocytes has been investigated. Activation, stimulation, and relative toxicity factor indices are studied, as well as possible relationships between DNA and protein synthesis rates, as measured by simultaneous tritiated thymidine (3H-TdR) and 14C-leucine uptake. Studies of the two new indices, the metabolic self and cross coupling indices lead to the prediction that there are three morphologically distinct subpopulations of EBV-transformed lymphocytes with different abrin receptor site concentrations. This prediction is supported by SEM morphological differences. Using data on EBV-transformed lymphocyte cell density as a function of time and dose of abrin, one can demonstrate that the mean number of receptors bound-EBV-lymphocyte needed to exert a biological influence lies in the interval 59,264 receptors/cell to 370.040 receptors/cell. Using a simple packing model, one can demonstrate that a theoretical estimate places the number of binding sites between 57,600 receptors/cell and 360,000 receptors/cell.
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PMID:On the dynamics of abrin binding to receptor sites in normal and Epstein Barr Virus transformed lymphocyte cell cultures. 627 62

The effects of treatment with varying doses of abrin, a D-galactose binding lectin, on DNA and protein synthesis of normal and Epstein Barr virus-transformed lymphocytes have been investigated. Studies of activation and stimulation indices, as well as two new indices; the metabolic self and cross-coupling indices, lead to the prediction that there are three morphologically distinct subpopulations of EBV-transformed lymphocytes with different abrin binding site numbers. This conclusion is supported by SEM morphological differences.
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PMID:Studies on toxicity and binding kinetics of abrin in normal and Epstein Barr virus-transformed lymphocyte culture-I: experimental results - 2. 627 17

The in vitro stimulation of [3H]thymidine uptake into lectin-activated lymphocytes in the presence of various sera was studied. The mean precision of the assay is 5%, and the study of the confidence intervals shows variations from 4% to 12%. Compared to a normal reference serum (fixed as 1 U/ml), the serum thymidine uptake stimulating activity (mean +/- SEM) was 1.04 +/- 0.07 U/ml in normal adult males, 2.63 +/- 0.48 U/ml in acromegalic patients, 1.51 +/- 0.13 U/ml in constitutional dwarfism and 0.37 +/- 0.04 U/ml in untreated hypopituitary dwarfism with a significant difference between the groups (P less than 0.001). In patients with hypopituitarism a single im hGH dose (6 mg/m2 increased the thymidine uptake stimulating activity of serum within 24 to 48 h following injection. The effects of directly adding hGH, insulin and T3 to the assay, have been studied: pharmacological concentrations are required to produce only a slight effect. Physiological concentration of a purified preparation of somatomedin A stimulated thymidine uptake and its effect is increased in the presence of serum. These data demonstrate that [3H]thymidine uptake into lectin-activated lymphocytes is stimulated by a GH-dependent serum factor. The data suggest that this method should be proposed for an accurate and sensitive biological evaluation of serum thymidine uptake stimulating activity.
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PMID:A hormonally controlled serum factor stimulating the thymidine uptake into lectin-activated lymphocytes. 702 10

The lectins concanavalin A (Con A), wheat germ agglutinin (WGA), Ricinus communis agglutinin (RCA) I+II and the polycation protamine sulfate were applied directly to renal glomerular podocytes by micropuncture techniques in vivo; others received a control solution. To make visible the distribution of lectins, some rats were given fluorescein isothiocyanate-conjugated Con A. The glomeruli undergoing the micropuncture experiments were labeled and then prepared for SEM and TEM observation, in some cases also for histochemical analysis. Comparatively, the effect of application of the Con A and protamine sulfate solution by intraarterial infusion was studied. The glomeruli of a total of 100 Munich-Wistar rats were studied. Con A and WGA cause varying degrees of 'retraction' of the foot processes of the podocytes when applied using the techniques of micropuncture. Intraarterial infusion of a Con A solution, on the other hand, causes no changes in the podocytes. RCA II, applied for 10 min using micropuncture techniques, causes thickening and swelling of the foot processes as well as the formation of intercellular junctions ('agglutination'). RCA I, on the other hand, causes no changes in the podocytes of the rat glomerulus. Glomeruli treated with the micropuncture application of the polycation protamine sulfate demonstrate largely 'agglutination' and only sometimes localized minimal retraction of the foot processes of the podocytes. The intraarterial infusion of protamine sulfate causes almost exclusively 'agglutination' of the podocyte foot processes. Retraction of the podocyte foot processes is probably a result of the active movement of the podocytes, which in turn induced by attachment of lectines to the lectin receptors in glycocalyx of the podocyte cell membrane. Simple reduction of the polyanions in the podocyte cell membrane by protamine sulfate appears to cause only simple electrostatic interaction which then results in 'agglutination' of the podocyte foot processes.
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PMID:Influence of the lectins and polycation on the configuration of renal podocytes: a scanning electron microscopic study of renal podocytes after micropuncture of the glomerulus in vivo. 732 26

In order to provide a device releasing drugs in a controlled manner and having targetability to specific organs or cells, chitosan-gel microspheres, CMS, crosslinked with glutaraldehyde, immobilizing 1-[N-(5-aminopentyl) carbamoyl]-5-fluorouracil, 1, coated with anionic polysaccharides, such as 6-O-carboxymethyl-N-acetyl-alpha-1,4-polygalactosamine (CM-NAPGA), 6-O-carboxymethyl-chitin, alginic acid and heparin, by polyelectrolyte complex membrane formation were prepared. When chitosan was crosslinked with glutaraldehyde, 1 was simultaneously immobilized into CMS by Schiff's base formation. Average diameter of CMS obtained was estimated to be about 0.5-1.0 micron by SEM observation. In physiological saline media, only free 5-FU was released from the CMS but 1 and any 5-FU derivative was not. Release rate of 5-FU from the CMS was reduced by coating with polyelectrolyte complex membrane of cationic chitosan and anionic polysaccharides. CMS coated with CM-NAPGA showed a lectin-mediated specific aggregation phenomenon by addition of Abrus precatorius agglutinin. Moreover, the CMS immobilizing 1 coated with CM-NAPGA showed higher growth-inhibitory effect against SK-Hep-1 (human hepatoma) cells in vitro than the CMS coated with other polysaccharides.
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PMID:Release behaviour of 5-fluorouracil from chitosan-gel microspheres immobilizing 5-fluorouracil derivative coated with polysaccharides and their cell specific recognition. 838 99


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