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At least 451 records · Page 25Linked to original sources
PubMed1987

Nanovid tracking: a new automatic method for the study of mobility in living cells based on colloidal gold and video microscopy.

We describe a new automatic technique for the study of intracellular mobility. It is based on the visualization of colloidal gold particles by video-enhanced contrast light microscopy (nanometer video microscopy) combined with modern tracking algorithms and image processing hardware. The approach can be used for determining the complete statistics of saltatory motility of a large number of individual moving markers. Complete distributions of jump time, jump velocity, stop time, and orientation can be generated. We also show that this method allows one to study the characteristics of random motion in the cytoplasm of living cells or on cell membranes. The concept is illustrated by two studies. First we present the motility of colloidal gold in an in vitro system of microtubules and a protein extract containing a kinesin-like factor. The algorithm is thoroughly tested by manual tracking of the videotapes. The second study involves the motion of gold particles microinjected in the cytoplasm of PTK-2 cells. Here the results are compared to a study using the spreading of colloidal gold particles after microinjection.

Animals↗
PubMed1990

[Results of tri-component treatment of lung cancer (pre- or postoperative radioisotope teletherapy and radioactive colloid gold Au-198)].

Radical surgery adjuvant to pre- or postoperative teleradiotherapy and intravenous injection of radioactive colloid gold did not aggravate the course of the postoperative period in pulmonary carcinoma patients, nor did it increase the total number of postoperative complications and the postoperative mortality. Side effects of treatment presenting as radiation responses were transitory and cured conservatively. Three-component treatment for pulmonary carcinoma, including preoperative irradiation in doses 20, 30 Gy, radical surgery, and intravenous 198Au after surgery is indicated to patients with Stage III pulmonary adenocarcinoma and epidermoid cancer, whose 5-year survival rate elevated by 36 and 30 percent, respectively, as against surgical treatment, and to those with stages II and III metastatic adenocarcinoma and epidermoid cancer of the lungs, whose 5-year survival rate increased by 39 and 32 percent, respectively, as against those treated surgically.

Aged↗
PubMed1999

[Use of protein-polysaccharide Brucella antigen labeled with colloidal gold for detection of specific antibodies by the dot-immunoassay method].

Antibrucella antibodies were detected by dot-immunoassay with colloid gold label of antigen. The specific antigen was protein-polysaccharide complex (PPC) isolated from vaccine strain Brucella abortus 19 BA by acetic acid hydrolysis of bacterial cells. Dot immunoassay with PPC labeled with colloid gold was effective in testing cattle, rabbit, and human sera for antibrucella antibodies. The proposed test system is simple, economic, highly sensitive and specific, and requires no expensive equipment and reagents, which are its advantages over routine serological tests.

Animals↗
PubMedDate not supplied

Blood clearance of radiolabeled gold colloid by the turkey mononuclear phagocytic system.

Radiolabeled gold colloid (198Au), which has been used to assess particle clearance in mammalian species, was used to assess blood-borne particle clearance in turkeys. When turkeys 16 weeks of age were injected intravenously with these particles, there was greater than a 98% decrease in blood gamma emission from 1 minute to 6 minutes postinjection. Uptake of particles was predominantly hepatic with minor uptake by the spleen and bone marrow. Negligible uptake was observed in lung, kidney, and skeletal muscle. Autoradiography demonstrated particles within Kupffer cells of the liver, periarteriolar macrophages of the spleen, and bone-marrow macrophages. Particles could not be demonstrated within the lung or kidney. The mononuclear phagocyte system responsible for blood particle clearance in turkeys is therefore located predominantly within the liver, spleen, and bone marrow and is similar to that of rats, mice, rabbits, and dogs. Pulmonary intravascular macrophages, which have recently been described in ruminants and pigs, are not apparent in this species.

Animals↗
PubMed1995

Colloidal gold conjugated monoclonal antibodies, studied in the BIAcore biosensor and in the Nycocard immunoassay format.

Interactions between immobilized capture monoclonal antibodies (mAbs), analyte molecules and colloidal gold conjugated second monoclonal antibodies have been investigated in the BIAcore biosensor and in the Nycocard immunoassay format. This report focuses on six monoclonal antibodies against human heart myoglobin, although, results with other antigens are also discussed. The BIAcore was used to screen monoclonal antibodies as antigen capture reagents, and for their function as colloidal gold conjugated second antibodies in the Nycocard. Some antibodies with low affinity caused by a rapid antigen dissociation rate, showed high affinity kinetics when used unlabelled or as gold conjugated detector reagents. One gold conjugated mAb with excellent properties in the Nycocard, showed double binding to one epitope, when tested in the BIAcore. The real time visualization of association and dissociation rates was a unique tool in the elucidation of antigen-antibody interactions. Our study confirmed that good antibody candidates selected with the BIAcore must always be tested in their actual conjugation situation before final optimization.

Antibodies, Monoclonal↗
PubMed1993

Silver-enhanced colloidal-gold labelling of rabbit kidney collecting-duct cell surfaces imaged by scanning electron microscopy.

The luminal cell surfaces of rabbit kidney cortical collecting-duct cells were labelled with peanut lectin (PNA) and investigated by scanning electron microscopy. Labelling was performed either on 20-microns-thick cryostat sections from prefixed and cryoprotected rabbit kidney tissue or on cultured collecting-duct epithelium using biotinylated PNA and a 6-nm colloidal-gold-coupled antibody against biotin. Colloidal-gold labels were detected at low magnification (2000-4000x) using silver enhancement. Coating with chromium allowed simultaneous imaging of both cell-surface morphology and labelling topography in the backscattered electron imaging mode. Our results show that PNA binding is specific for a subtype of intercalated cells equipped with microvilli on the luminal surface. The presented method promises to be useful for the identification of specific cell types in heterogeneous tissues.

Aging↗
PubMedDate not supplied

Spectroimmunochemistry using colloidal gold bioconjugates.

Using surface-enhanced infrared absorption (SEIRA) spectroscopy of dry films of colloidal gold (CG) bioconjugates with protein A, it is shown that certain characteristic bands of the protein (e.g., amide I, amide II and some other vibration modes) are essentially affected by the metal surface. Thus, the method may be used for controlling the quality of such bioconjugates. Moreover, it is demonstrated that the biospecific reaction of protein A attached to CG particles with human immunoglobulin G (IgG) results in further essential changes in SEIRA spectra, providing a means for an easy and rapid IR spectroscopic detection of biospecific immunochemical interactions (i.e., spectroimmunochemistry). The results obtained can form a basis for developing test systems for detecting various biospecific interactions.

Binding Sites↗
PubMed1987

Colloidal gold--a powerful tool in scanning electron microscope immunocytochemistry: an overview of bioapplications.

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.

Animals↗
PubMed1983

Colloidal gold, a useful marker for antigen localization on follicular dendritic cells.

Bovine serum albumin (BSA) bound to colloid gold particles (BSA-gold; 20 nm diameter) and injected into preimmunized mice was found at ultrastructural level in different locations of the lymph nodes. It was detected particularly in the secondary lysosomes of macrophages and between the cytoplasmic processes of the follicular dendritic cells. Between these processes the gold particles were isolated or grouped in clusters; they were in close contact with cell membranes or embedded in dense material. Colloidal gold injected alone was not retained on these cells. The presence of anti-BSA antibodies in the serum was necessary for trapping of BSA-gold particles on follicular dendritic cells. Injections of BSA alone after BSA-gold had been administered to preimmunized mice eliminated most of the BSA-gold from the dendritic processes. BSA-gold is thus trapped in the form of immune complexes which behave characteristically. BSA-gold is thus a suitable marker for antigen localization. Being small and electron dense it permits more precise location than radioactive markers.

Animals↗
PubMed1984

Receptor-mediated endocytosis of immunoglobulin-coated colloidal gold particles in cultured mouse peritoneal macrophages.

Endocytosis of immunoglobulin G (IgG)-coated colloidal gold particles in cultured mouse peritoneal macrophages was studied by scanning and transmission electron microscopy. At 4 degrees C, the tracers adhered to the plasma membrane and accumulated in coated pits located in the bottom of furrows or deep invaginations on the cell surface. In the presence of an excess of unlabeled mouse IgG, cellular binding of the tracer was reduced by 80 to 90%. After warming to 37 degrees C, surface-bound tracer particles were rapidly ingested and transported to small and large vesicles lacking membrane coat. From here, they were then passed over to multivesicular bodies and lysosomes characterized by their content of myelin-like figures and other inclusions. Double-labeling experiments with IgG-coated colloidal gold particles of two different sizes (20 and 5 nm diameter) indicated that the plasma membrane was depleted of binding sites after uptake of a polyvalent ligand. The restoration of the binding capacity was a slow process requiring ongoing protein synthesis. On the basis of these observations, a model for endocytosis of immune complexes in macrophages is presented. It includes the following four steps: IgG-containing macromolecular aggregates bind to specific receptors in the plasma membrane. These appear to be preclustered in coated pits or able to move laterally within the membrane even at 4 degrees C. The receptor-ligand complexes are internalized and transferred sequentially to larger uncoated vesicles or endosomes, multivesicular bodies, and lysosomes with inclusions of varying appearance. Receptors and ligands are degraded within the lysosomes.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1981

Colloidal gold markers and probes for routine application in microscopy.

Colloidal gold can be used as an electron-dense cytochemical probe for direct or indirect labelling techniques. Gold markers can be prepared in a size range of 5-150 nm, and show size-dependent shape characteristics and absorption spectra. Size and shape distribution increases with mean particle diameter, with appreciable overlapping between populations of different mean size. Using radio isotope-binding assays, spectrophotometric analysis and an innovative rapid microtitration technique, the effect of pH, ionic strength and protein concentration on gold-protein interaction has been studied. Efficient adsorption of protein to gold occurs at, or near, the pI of the protein. The amount of protein needed to effect stabilization is both a function of pH and of ionic strength, but does not reflect the amount of protein binding for all proteins. There is evidence for multilamellar adsorption of proteins to gold, which is discussed in context of the bioactivity, and stability of the probe. A working protocol for the routine reproducible manufacture of protein-gold probes is given, making use of the microtitration assay.

Colloids↗
PubMed1991

Colloidal gold as a permanent marker of cells.

We have demonstrated that colloidal gold-labelled serum proteins are taken up by a number of cells in cultures established from the postnatal rodent neopallium. The colloidal gold enters and remains within secondary lysosomes over extended periods of time and, as well, persists after the subculture of these cells. The cell types that readily take up the label in our culture system are type-1 astrocytes, glial precursor cells and macrophages, whereas, only a small number of oligodendrocytes take up the label. The use of serum proteins to introduce colloidal gold into cells therefore seems to be a convenient and easy way to permanently mark cells.

Animals↗
PubMed1986

Controlled growth of colloidal gold particles and implications for labelling efficiency.

A new method is reported for the preparation of colloidal gold particles with diameters ranging between 5 and 12 nm. The initial gold particle population, with an average diameter of 5.6 +/- 0.9 nm, is prepared by reduction of chloroauric acid with white phosphorous. An increase in particle diameter by growth is obtained by reduction of chloroauric acid with white phosphorous in the presence of colloidal gold particles. The labelling efficiency of these gold particles, conjugated with protein A, in indirect immunolabelling experiments is investigated by labelling of beta-galactosidase on ultrathin cryosections of Escherichia coli cells. We demonstrate that the labelling efficiency is at least dependent on particle diameter, probe concentration and preparation method. In addition it is shown, that with this new method, gold particle populations can be prepared with minor overlap in diameter spreading. Therefore these gold probes are suitable for qualitative double labelling experiments. The quantitative aspect of immunolabelling is discussed.

Colloids↗
PubMed1984

Unlabeled antibody methods in electron microscopy: a comparison of single and multistep procedures using colloidal gold.

A comparative study of five unlabeled antibody methods was conducted on the electron microscopic level using bridging techniques and colloidal gold. The study was based on the principles of the single-step colloidal gold (GLAD) method (Larsson L: Nature 282:743, 1979) and the multistep single- and double-bridge techniques used in postembedding immunoperoxidase procedures (PAP) (Sternberger LA: Immunocytochemistry, 2nd ed. Wiley, New York, 1979). Using medullary thyroid carcinoma and the same lot of primary antiserum (goat anti-calcitonin) for each procedure, it was shown that adequate localization of calcitonin with the single-step GLAD method was attainable only at dilutions of 1:100 or lower. The single-bridge technique using goat anti-calcitonin, sheep anti-goat immunoglobulin (Ig)G, and goat anti-calcitonin and antigen-coated gold, respectively, worked well at dilutions of up to 1:5000 but not at dilutions of 1:10,000, while single- and double-bridging techniques utilizing goat anti-calcitonin, sheep (Sh) anti-goat IgG, and sheep anti-goat IgG-coated gold produced good localization at a 1:10,000 dilution of primary antiserum. A two-step method using goat anti-calcitonin and sheep anti-goat IgG-coated gold, respectively, appeared to be the most sensitive technique, with adequate antigen localization occurring at a dilution of 1:25,000. While in our hands the two-step method appeared superior in sensitivity to the single-bridge IgG-coated gold technique, each method has its own advantages depending on the individual needs of the researcher.

Animals↗
PubMed2005

Magnetic bead-based chemiluminescent metal immunoassay with a colloidal gold label.

A novel, sensitive chemiluminescent (CL) immunoassay has been developed by taking advantage of a magnetic separation/mixing process and the amplification feature of colloidal gold label. First, the sandwich-type complex is formed in this protocol by the primary antibody immobilized on the surface of magnetic beads, the antigen in the sample, and the second antibody labeled with colloidal gold. Second, a large number of Au3+ ions from each gold particle anchored on the surface of magnetic beads are released after oxidative gold metal dissolution and then quantitatively determined by a simple and sensitive Au3+-catalyzed luminol CL reaction. Third, this protocol is evaluated for a noncompetitive immunoassay of a human immunoglobulin G, and a concentration as low as 3.1 x 10(-12) M is determined, which is competitive with colloidal gold-based anodic stripping voltammetry (ASV), colorimetric ELISA, or immunoassays based on fluorescent europium chelate labels. The high performance of this protocol is related to the sensitive CL determination of Au3+ ion (detection limit of 2 x 10(-10) M), which is 25 times higher than that by ASV at a single-use carbon-based screen-printed electrode. From the analytical chemistry point of view, this protocol will be quite promising for numerous applications in immunoassay and DNA hybridization.

Biosensing Techniques↗
PubMed1986

Detection of mucus glycoconjugates in human conjunctiva by using the lectin-colloidal gold technique in TEM. II. A quantitative study in dry-eye patients.

The mucus glycoconjugates produced by conjunctival goblet cells in dry-eye patients were studied by a specific cytochemical reaction in Transmission Electron Microscopy (TEM). Four lectins, proteins of vegetal origin which specifically bind glycosidic residues, (WGA, PNA, SBA and ConA) were used conjugated with colloidal gold as ultrastructural marker. We performed a quantitative analysis by counting the colloidal gold particles present on mucus granules. The results were compared with normal conditions. We found a decrease in sialic acid, N-acetyl-glucosamine, N-acetyl-galactosamine and galactose-N-acetyl-galactosamine and an increase in mannose. The different content of glycoconjugates in goblet cells may reflect in the change of physical and functional properties of mucus. We think these data may be useful in the search for a therapeutic mucomimetic drug.

Carbohydrate Metabolism↗