Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Gold Colloid”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 73 records · Page 4Linked to original sources

Delayed cerebrovascular complications of intrathecal colloidal gold.

OBJECTIVE: Therapy with intrathecal colloidal gold has been used in the past as an adjunct in the treatment of childhood neoplasms, including medulloblastoma and leukemia. We describe the long-term follow-up period of a series of patients treated with intrathecal colloidal gold and emphasize the high incidence of delayed cerebrovascular complications and their management. METHODS: Between 1967 and 1970, 14 children with posterior fossa medulloblastoma underwent treatment at the University of Minnesota. Treatment consisted of surgical resection, external beam radiotherapy, and intrathecal colloidal gold. All patients underwent long-term follow-up periods. RESULTS: Of the 14 original patients, 6 died within 2 years of treatment; all experienced persistent or recurrent disease. The eight surviving patients developed significant neurovascular complications 5 to 20 years after treatment. Three patients died as a result of aneurysmal subarachnoid hemorrhage, and five developed ischemic symptoms from severe vasculopathy that resembled moyamoya disease. CONCLUSION: Although therapy with colloidal gold resulted in long-term survival in a number of cases of childhood medulloblastoma, our experience suggests that the severe cerebrovascular side effects fail to justify its use. The unique complications associated with colloidal gold therapy, as well as the management of these complications, are presented. We recommend routine screening of any long-term survivors to exclude the presence of an intracranial aneurysm and to document the possibility of moyamoya syndrome.

Adolescent↗

Demonstration of anionic sites in human eccrine and apocrine sweat glands in post-embedded ultra-thin sections with cationic colloidal gold: effect of enzyme digestion on these anionic sites.

We localized anionic sites ultrastructurally in human eccrine and apocrine sweat glands with a poly-L-lysine-gold complex (cationic colloidal gold). Anionic sites were labeled by incubating Lowicryl K4M-embedded sections on droplets of cationic colloidal gold. In eccrine sweat glands, colloidal gold particles were restricted to the basolateral membrane of the secretory cells at low pH, whereas the luminal membrane did not react with the gold particles. Chondroitinase ABC digested these anionic sites. This indicates that chondroitin sulfate and/or dermatan sulfate constitutes anionic sites in the basal labyrinth of eccrine sweat glands. In apocrine sweat glands, the luminal membrane of the secretory cells showed strong reaction at low pH, whereas the contraluminal membrane did not show any reaction. Neuraminidase completely digested these anionic sites, which indicated that the anionic charge of the apocrine lumen was due to sialic acid. Differences in distribution and susceptibility to enzymes of anionic sites in cell membranes between eccrine and apocrine sweat glands may reflect functional differences between these glands. Dark cell granules in eccrine secretory cells were negative for the anionic sites when sections were labeled without any pre-treatment. However, pre-incubation of the grids on EGTA or deionized water unmasked the anionic sites on the dark cell granules. The positive staining after EGTA treatment was greatly decreased by reincubation with CaCl2. These results suggested that Ca blocked anionic sites in dark cell granules. Exposed anionic sites were digested with chondroitinase ABC. This indicated that chondroitinase ABC and/or dermatan sulfate composed the anionic sites in dark cell granules.

Anions↗

[Immunogenic properties of the colloidal gold].

We studied the capacity of colloidal gold for enhancing specific and nonspecific immune response in laboratory animals (rabbits, rats, and mice) immunized with antigens of various nature. The antibody titers obtained with colloidal gold as a carrier were higher as compared to the standard immunization techniques (free antigen or Freund's adjuvant). Application of colloidal gold increased nonspecific immune responses as well: lysozyme concentration in the blood, activity of the complement system proteins, as well as phagocytic and bactericidal activities. The obtained antibodies were tested by immunodot assay using gold markers. Immunization of the animals with colloidal gold conjugates with haptens as well as complete antigens was shown to induce formation of highly active antibodies without using other antigens such as complete Freund's adjuvant. In addition, antigen quantities for animal immunization with colloidal gold was by one order of magnitude lower as compared to the complete Freund's adjuvant immunization. This fact can point to direct adjuvant activity of colloidal gold.

Actins↗

Correlative Instrumental Neutron Activation Analysis, Light Microscopy, Transmission Electron Microscopy, and X-ray Microanalysis for Qualitative and Quantitative Detection of Colloidal Gold Spheres in Biological Specimens.

: Colloidal gold, conjugated to ligands or antibodies, is routinely used as a label for the detection of cell structures by light (LM) and electron microscopy (EM). To date, several methods to count the number of colloidal gold labels have been employed with limited success. Instrumental neutron activation analysis (INAA), a physical method for the analysis of the elemental composition of materials, can be used to provide a quantitative index of gold accumulation in bulk specimens. Given that gold is not naturally found in biological specimens in any substantial amount and that colloidal gold and ligand conjugates can be prepared to yield uniform bead sizes, the amount of label can be calculated in bulk biological samples by INAA. Here we describe the use of INAA, LM, transmission EM, and X-ray microanalysis (EDX) in a model to determine both distribution (localization) and amount of colloidal gold at the organ, tissue, cellular, and ultrastructural levels in whole animal systems following administration. In addition, the sensitivity for gold in biological specimens by INAA is compared with that of inductively coupled plasma-mass spectrometry (ICP-MS). The correlative use of INAA, LM, TEM, and EDX can be useful, for example, in the quantitative and qualitative tracking of various labeled molecular species following administration in vivo.

Journal Article↗

A review of the potential and versatility of colloidal gold cytochemical labeling for molecular morphology.

In the present article we review several postembedding cytochemical techniques using the colloidal gold marker. Owing to the high atomic number of gold, the colloidal gold particles are electron dense. They are spherical in shape and can be prepared in sizes from 1 to 25 nm, which renders this marker among the best for electron microscopy. In addition, because it can be bound to several molecules, this marker has the advantage of being extremely versatile. Combined to immunoglobulins or immunoglobulin-binding proteins (protein A), it has been applied successfully in immunocytochemistry. Colloidal gold particles 5-15 nm in size are excellent for postembedding cytochemistry. Particles of smaller size, such as 1 nm, must be silver enhanced to be visualized by transmission electron microscopy. We have elected to review the superiority of indirect immunocytochemical approaches using IgG-gold or protein A-gold (protein G-gold and protein AG-gold). Lectins or enzymes can be tagged with colloidal gold particles, and the corresponding lectin-gold and enzyme-gold techniques have specific advantages and great potential. Using an indirect digoxigenin-tagged nucleotide and an antidigoxigenin probe, colloidal gold technology can also be used for in situ hybridization at the electron microscope level. Affinity characteristics lie behind all cytochemical techniques and several molecules displaying high affinity properties can also be beneficial for colloidal gold electron microscopy cytochemistry. All of these techniques can be combined in various ways to produce multiple labelings of several binding sites on the same tissue section. Colloidal gold is particulate and can easily be counted; thus the cytochemical signal can be evaluated quantitatively, introducing further advantages to the use of the colloidal gold marker. Finally, several combinations and multiple step procedures have been designed to amplify the final signal which renders the techniques more sensitive. The approaches reviewed here have been applied successfully in different fields of cell and molecular biology, cell pathology, plant biology and pathology, microbiology and virology. The potential of the approaches is emphasized in addition to different ways to assess specificity, sensitivity and accuracy of results.

Animals↗

Thermodynamic and kinetic analysis of the interaction between hepatitis B surface antibody and antigen on a gold electrode modified with cysteamine and colloidal gold via electrochemistry.

Hepatitis B surface antibody (HBsAb) was immobilized to the surface of a gold electrode modified with cysteamine and colloidal gold as matrices to detect hepatitis B surface antigen (HBsAg). Differential pulse voltammetry (DPV) method was used for the investigation of the specific interaction between the immobilized HBsAb and HBsAg in solution, which was followed as a change of peak current in DPV with time. With the modified gold electrode, the differences in affinity of HBsAb with HBsAg at the temperatures of 37 and 40 degrees C were easily distinguished and the kinetic rate constants (k(ass) and k(diss)) and kinetic affinity constant K were determined from the curves of current versus time. In addition, the thermodynamic constants, DeltaG, DeltaH and DeltaS, of the interaction at 37 degrees C were calculated, which were -56.65, -64.54 and -25.45 kJ mol(-1), respectively.

Antigen-Antibody Reactions↗

Visual detection of IS6110 of Mycobacterium tuberculosis in sputum samples using a test based on colloidal gold and latex beads.

The IS6110 sequence was detected visually in sputum samples of tuberculosis patients using a bi-probe system. One of the probes was an oligonucleotide conjugated to colloidal gold particles, complementary to one end of the target strand. The other probe was an oligonucleotide conjugated to latex beads complementary to the other end of the target strand. In a reaction mix, these two probes bind to the target strand, and the latex beads are then separated by filtration. Bound latex beads have gold colloid particles at the other end of the target strand. These gold colloid particles were made visible to the naked eye by silver autometallography on the 'invisible' colloidal gold particles. The lower detection limit was 50 ng of genomic DNA of Mycobacterium tuberculosis. This new test, together with conventional PCR, was performed on DNA extracted from sputum samples of suspected tuberculosis patients. The new test was simple to perform, the results were visible to the naked eye, and the test was highly specific, as even single point mutations in the target strand sequence could be differentiated. The test could be useful in field-level laboratories because it requires no sophisticated equipment.

Bacteriological Techniques↗

High precision immunoscanning electron microscopy using Fab fragments coupled to ultra-small colloidal gold.

Ultra-small colloidal gold (less than 1 nm), bound to Fab fragments provides the shortest practical specific marker system to date and can be used in concert with field emission scanning electron microscopes to precisely locate antigenic sites. An "in-lens" FE-SEM equipped with a highly sensitive single crystal YAG-detector for backscattered electrons, as well as the use of advanced specimen preparation techniques based on cryofixation, are among the indispensible prerequisites. A T-even type Escherichia coli bacteriophage, Tu II*-46, was chosen to study properties of the immunogold labeling system. Distinct regions on the tail fibers of this phage were labeled with Fab fragments derived from antibodies against the related phage Tu II*-6. The tail fibers are composed of pairs of homologous proteins, thus offering two identical antigenic sites at the same locus on the tail fibers. Fab fragments can be visualized in the SEM at high accelerating voltage (30 kV) without any additional marker. This permits comparison of the labeling characteristics of unmarked and colloidal gold-marked Fab fragments. Unmarked Fab fragments often bind by pairs (two singlet Fab fragments bound opposed to each other along the axis of the tail fiber). The labeling efficiency of unmarked Fab fragments was greater than that of ultra-small gold-labeled Fab fragments. Binding by pairs was not seen after labeling with ultra-small gold-Fab fragments. The conjugates used in this study exhibited one colloidal gold per Fab fragment.

Animals↗

Preparation of Aqueous Gold Colloid by Vapor Deposition Method

Gold vapor and water vapor were co-condensed on a cooled surface and then the ice was melted to obtain highly pure aqueous gold colloid. After removing gold aggregate, we obtained a supernatant solution of gold which is transparent and purple in color. A surface plasmon resonance absorption peak appeared at about 550 nm. The gold colloid was stable for more than a year without any additives.

Journal Article↗

Separation and recovery of intact gold-virus complex by agarose electrophoresis and electroelution: application to the purification of cowpea mosaic virus and colloidal gold complex.

Colloidal gold has been coupled to a mutant cowpea mosaic virus (CPMV), which contains 60 cysteine residues on the surface. A purification process was developed to separate the gold-containing viral nanoblocks (VNBs) from the free gold. Agarose electrophoresis was utilized to separate the mixture followed by electroelution of the desired sample to recover the intact virus. Mobility of Au-VNB and free colloidal gold was facilitated by the addition of thioctic acid (TA). 30% of the gold-containing virus was recovered after electroelution as determined by absorbance measurements. Histogram analysis of transmission electron microscopy (TEM) images demonstrated the efficient separation of gold-containing virus from free gold. TEM and scanning electron microscopy (SEM) images indicated that the virus was recovered intact. Monodisperse spherical particles of nominal size of 45 nm were observed under SEM.

Comovirus↗

Detection of differences in oligonucleotide-influenced aggregation of colloidal gold nanoparticles using absorption spectroscopy.

A rapid, simple, and reproducible assay is described that can be used to detect differences in the ability of oligonucleotides to influence the aggregation of colloidal gold nanoparticles. The aggregation reaction of the gold colloid was monitored through UV-visible absorption spectroscopy. Single isolated colloidal gold particles have a surface plasmon resonance manifested as a single absorbance peak at approximately 520 nm, and aggregated gold complexes develop new red-shifted peaks/shoulders depending on the nature and extent of the aggregated complex. A simple ratiometric study of the area under the single and aggregated plasmon resonance peaks thus gives information about the extent of the aggregation. It is postulated that differences in dynamic flexibility of the oligonucleotides affect their influence on the aggregation state of the gold nanoparticles. The results of this study provide new clues toward unraveling the causes behind the preferential affinity of the Hermes transposable element for certain insertion sites compared to other sequences that also contain recognizable target sites. The technique is robust and thus can potentially be used to study similar questions for numerous transposable elements and target sequences.

DNA Mutational Analysis↗

Studies on the interaction of colloidal gold and serum albumins by spectral methods.

The interactions of colloidal gold and serum albumins, including bovine serum albumin (BSA) and human serum albumin (HSA), were studied by fluorescence and absorption spectrometry. Fluorescence quenching spectrometry was applied to study the interactions between colloidal gold and serum albumins. At pH 7.4 phosphate-buffered saline (PBS), the intensity of fluorescence emission spectrum of serum albumins decreased in the presence of colloidal gold, which indicated that colloidal gold quenched the fluorescence of serum albumins. Experimental results indicated that the combination reactions of colloidal gold and serum albumins were static quenching processes. Based on the effect of colloidal gold on fluorescence intensity, the binding constants, the numbers of binding sites and the acting forces between colloidal gold and serum albumins were found.

Animals↗

Investigation on the interaction between colloidal gold and human complement factor 4 at different pH by spectral methods.

The interaction between colloidal gold and human complement factor 4 (human C4) at different pH was investigated by spectral methods, including absorption and resonance light-scattering spectrometry. According to the changes of color and absorption spectra of colloidal gold solution in presence of human C4, the interaction between colloidal gold and human C4 was quantitatively investigated using a semi-empirical "flocculation parameter". At the same time, the changes of resonance light-scattering spectra and transmission electron microscopy (TEM) images indicate that the aggregation of colloidal gold happens by electrostatic interaction in presence of human C4 in the pH range 5-6. However, the colloidal gold solution remains stable at pH >6 and pH <5 due to the repulsive electrostatic interaction between colloidal gold and human C4. The flocculation parameter is directly proportional to the concentration of human C4 in the range from 9.7 to 233.0 microgl(-1). In addition, the interactions between the colloidal gold and bovine serum albumin (BSA) as well as human serum albumin (HSA) were also investigated using the same methods. It was found that there was no aggregation of colloidal gold in presence of BSA and HSA in the pH range 5-6. However, when the pH of solution is 4, the aggregation of colloidal gold happens. Because BSA and HSA have different structure, the intensity of aggregation of colloidal gold in presence of BSA is greater than that in presence of HSA at pH 4.

Animals↗

Triple immunological staining with colloidal gold, fluorescein and rhodamine as labels.

Colloidal gold particles are detectable by light microscopy with polarized light in the same epi-illumination system as for fluorescence microscopy. Colloidal gold particles can thus be used in combination with a fluorochrome for the combined immunological detection of surface membrane and cytoplasmic markers. We analyzed human bone marrow cells by a triple immunological staining for 3 different markers, using colloidal gold, fluorescein and rhodamine as labels. Our results demonstrate that such a triple immunological staining provides a powerful tool for study of the heterogeneity of small cell populations.

Adult↗

Sulphated glycosaminoglycans in guinea pig eosinophils studied by means of cationic colloidal gold.

Using bone marrow embedded in hydrophilic resin Lowicryl K4M and cationic colloidal gold pH 1.0 labelling, we studied sites of sulphation and sulphated glycosaminoglycans ultrastructurally in various maturational stages of both eosinophil granulocytes and eosinophil granules of guinea pig. Eosinophil granules reacted positively to cationic gold, the pattern of labelling varying according to the degree of cell maturation. The formation of eosinophil granules takes place throughout the myelocyte stage. Early eosinophil myelocytes contain a large Golgi apparatus with active granulogenesis, while late ones contain a small and less active Golgi apparatus. All the immature granules were labelled positively. However, mature granules with a central crystal bar lost their affinity towards colloidal gold. Interestingly, strong colloidal gold labelling was also observed in the trans to transmost Golgi apparatus, especially in immature eosinophil granulocytes. This indicates that sulphation of glycosaminoglycans occurs in the trans to transmost Golgi apparatus of eosinophil granulocytes. Prior absorption with poly-L-lysine prevented colloidal gold labelling of tissue sections. Methylation of sections at 37 degrees C did not alter the gold labelling, whereas the labelling disappeared after methylation at 60 degrees C. Prior treatment with chondroitinase ABC or heparinase I abolished the majority of colloidal gold labelling in immature eosinophil granules. Taking these results together, we conclude that immature eosinophil granules contain sulphated glycosaminoglycans including chondroitin sulphate or heparan sulphate or both.

Animals↗

[Use of colloidal gold in ultrastructural cytochemistry].

Colloid gold stabilized by macromolecules with various binding characteristics proved to be usable in transmission electron microscopy: Nucleic acids localization was studied in tissue cultures after embedding by techniques autoimmune serum-protein A--gold and RNase--gold. Technique with serum autoantibodies against double-stranded DNA resulted in marking condensed chromatin. Further experiments with ultrastructural localization of other autoimmune components seemed to be perspective and of diagnostic importance. Technique with RNase--gold complex marked especially ribosomes, nucleolus and interchromatin nuclear spaces. Herpes virus, rotavirus and enterovirus were identified in negative contrast by the technique antivirus serum--protein A--gold. A higher warrant of evidence achieved by the method may be used in virologic diagnosis. A small amount of tubulin was found in isolated permeabilized nuclei of Xenopus laevis by a direct immunocytochemical method with complex monoclonal IgG against tubulin-gold. Binding of complex of triiodothyronine-bovine serum albumin--gold on the cytoplasmic membrane of LEP cells in a short term tissue culture showed a possibility of tracing non-peptidic hormones binding on specific receptors.

Animals↗

Double labelling of cell surface antigens with colloidal gold markers.

Particles of colloidal gold of different diameters (15 nm and 40) have been used to distinctively label different surface antigens expressed on the surface of human peripheral blood B and T lymphocytes. Silver enhancement has been used to facilitate the observation of the gold particles. Observations were carried out in the backscattered electron imaging mode of the scanning electron microscope. Two different methods have been compared: in Method I the two antigens have been identified by monoclonal antibodies of different classes (IgG and IgM); in Method II monoclonal antibodies of the same subclass were used but the ligands were different (goat anti-murine Ig versus biotin/streptavidin). Some cross-reactivity was observed with Method I, but not with Method II.

Animals↗