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PubMed2004

Colloidal chitin stained with Remazol Brilliant Blue R, a useful substrate to select chitinolytic microorganisms and to evaluate chitinases.

A simple and sensitive method based on the use of colloidal chitin stained with Remazol Brilliant Blue R (RBB) is proposed to evaluate chitinase activity. If this colloidal-stained substrate is included as a carbon source in a liquid medium, this technique allows the selection or the comparison of chitinolytic microorganisms. The colloidal substrate is proportionally solubilized and the dye released is spectrophotometrically quantified at 595 nm. The procedures used for the staining and fixing of RBB in the colloidal chitin, and a comparison with the commercial substrate chitin-azure, are presented. The influence of several physicochemical and enzymatic parameters on the release of dyes is also shown. Both stained substrates were used for studying the effect of pH, substrate concentration, temperature and time on the chitinase reaction of Bacillus thuringiensis Bt-107.

Anthraquinones↗

PubMed1979

Intracavitary uses of colloids.

Pleural and peritoneal effusion secondary to primary malignancy is a significant problem in the management of the cancer patient. Respiratory embarrassment and discomfort associated with the formation and collection of fluid in the chest and abdomen are among the most distressing symptoms encountered as a result of malignant disease. The guidelines for treatment should be based on respiratory symptoms, and with the understanding that the procedure is palliative. Both surgical and medical forms of treatment have been used. These include thoracostomy-tube drainage alone or with the instillation of antimicrobial agents. Pleurectomy is effective but should be reserved for situations in which conservative approaches have failed. Antitumor agents, such as nitrogen mustard, are effective but toxic. The mode of action of antineoplastic agents is related to their ability to cause pleural sclerosis and obliterate the pleural space. Systemic chemotherapy and external beam radiation are rarely effective. The intracavitary application of radioactive colloids has been used since 1945. Colloidal radioactive gold Au 198 has been replaced by the pure beta emitter, colloidal chromic phosphate P 32. Instillation of a colloidal suspension of radioactive phosphorus represents a significant and effective palliative therapeutic modality for malignant effusion.

Adult↗

PubMed2000

Coupling of hydrodynamic and electric interactions in adsorption of colloidal particles.

The role of the coupling between hydrodynamic and electric interactions in adsorption of colloid particles is reviewed. First the general formulation of the problem of fluid motion connected with the macroscopic suspension flow as well as microscopic particle motion is presented together with the general description of the colloid particle adsorption. Then two limiting cases are considered: motion of uncharged particles and electric interactions of stationary particles. The theoretical consideration are supported by illustrative experimental results. Next the electrokinetic effects in particle adsorption process are considered and the theoretical background for the description of these effects is given. The effect of the electroviscous drag on the particle aggregation and adsorption kinetics is discussed. Also the electrokinetic lift force, which is an example of the non-linear electrokinetic effect, is considered and the possible implications on particle adsorption are examined. In the following part of the review the influence of electro-hydrodynamic coupling on the particle transport to the interface is considered. First the 'inverse salt effect' for the initial adsorption flux when the interface is not covered by adsorbed particles is examined. Then, the electro-hydrodynamic scattering effect which occurs when the interface is partially covered by particles is considered and its experimental evidence concerning the adsorption kinetics and the local structure of adsorbate is considered. Also a novel application of the scattering effect to measure interparticle forces the 'colloid particle collider' is presented and some experimental results obtained using this technique are shown. All results reported in this review suggest strong coupling of the hydrodynamic and electric forces and their pronounced influence on colloid particle adsorption.

Adsorption↗

PubMed2001

Is the use of albumin in colloid prime solution of cardiopulmonary bypass circuit justified?

BACKGROUND: Albumin in the priming solution precoats the surface of the cardiopulmonary bypass circuit, supposedly causing delayed adsorption of fibrinogen and reduced activation and adhesion of platelets. This action may result in lower transoxygenator resistance. Because our institution uses a colloidal prime solution (Gelofusine), questions were raised about the value of albumin in the prime solution. We decided to focus on the clinical effects of transoxygenator resistance. METHODS: Sixty adults undergoing elective cardiac operations were randomly divided into three groups: a group with 20-g albumin (n = 20), a group with 2-g albumin (n = 20), and a group with no albumin (n = 20) in the 1,600-mL colloidal prime. Patients older than 75 years and patients with a preoperative serum albumin level of 30 g/L or less were excluded. The transoxygenator resistance was measured throughout cardiopulmonary bypass. Beta-thromboglobulin levels were used to study contact activation of platelets. Measures of prothrombin F1,2 fragments were used as a marker of thrombin generation. Body surface area, age, preoperative albumin, hematocrit, hemoglobin, fibrinogen, platelet count, and colloid osmotic pressure levels were compared between groups. RESULTS: Base line characteristics and chosen control measurements were similar for all three populations. When comparing the observed transoxygenator resistance among the three different groups, no significant differences were noted. Prothrombin F1.2 fragments remained low for all the groups without significant differences. In the no-albumin group the level of beta-thromboglobulin appeared to be higher, but the difference was not statistically significant. CONCLUSIONS: Addition of albumin to prime solution in a cardiopulmonary bypass circuit that already contains colloids does not affect the transoxygenator resistance of the COBE Duo flat sheet oxygenator and does not affect prothrombin F1.2 and beta-thromboglobulin levels. Therefore additional costs for the albumin are not justified. Measurement of transoxygenator resistance is a reliable, simple method to determine the effects of a prime solution on the oxygenator surface in vivo.

Aged↗

PubMed2003

Surface-modified silica colloid for diagnostic imaging.

A method of preparing nanometer-sized oxide colloids suitable as substance carriers for size-sensitive diagnostic imaging and other biomedical applications is described. The nanometer-sized silica particles prepared by the Stober process were reacted with silane to obtain amine-terminated colloidal surfaces under aqueous conditions. The surface-modified colloids can be further treated to combine or conjugate with imaging agents and other diagnostic or therapeutic substances. The water-stable colloidal carriers are spherical and have a narrow size distribution that can be controlled to range from 10 to 200 nm.

Colloids↗

PubMed2003

Colloid-like cyst located in the prepontine region.

BACKGROUND: The term "colloid cysts" refers to nonneoplastic lesions located in the anterior part of the third ventricle. However, cysts morphologically identical to colloid cysts are found, albeit extremely rarely, through the neuraxis. CASE DESCRIPTION: We report a case of a 44-year-old man with a short history of headache and 5 years of bilateral hearing loss. Computed tomography (CT) and magnetic resonance imaging (MRI) scans showed an oval lesion located at the anterior surface of the pons. The tumor was excised through a right pterional transsylvian approach. Postoperatively, the hearing deficit remained unchanged. Otherwise, the patient made an excellent recovery. Histopathological examination showed a colloid-like cyst. CONCLUSIONS: Colloid-like cysts growing in the prepontine region are extremely rare. To date, only two similar cases have been reported in the literature. Patients present with headaches, hearing loss, or blurred vision.

Adult↗

PubMed1996

Microsurgical resection of colloid cysts using a stereotactic transventricular approach.

BACKGROUND: Several surgical approaches have proven effective in the management of colloid cysts. Cited disadvantages of the transventricular route are its difficulty in patients with small ventricles, and the risk of postoperative seizures; advantages include the avoidance of interhemispheric retraction and venous injury, and callosal section in the transcallosal route. METHODS: We retrospectively evaluated patient outcomes after minimally invasive transventricular microsurgical resection. Twenty patients underwent computed tomography-guided stereotactic resection of a colloid cyst based on trajectory planning through the middle frontal gyrus. The mean patient age was 38 years (range, 14-65 years). The colloid cyst was discovered incidentally in one patient; two patients presented in coma. Fourteen patients (70%) had preoperative hydrocephalus. RESULTS: Total or near-total (only a small remnant of cyst wall left attached to the fornix or thalamostriate vein) cyst removal was achieved in all patients. Mean follow-up after surgery was 4.3 years (range, 0.5-11 years). All patients had an excellent outcome (100%) with return to full function or employment status. Postoperative morbidity occurred in one patient (5%) who sustained a small caudate nucleus hemorrhagic contusion associated with temporary hemiparesis. A single postoperative seizure occurred in one patient 5 months after surgery; no patient developed a persistent seizure disorder. CONCLUSIONS: This technique relies on the use of a precisely placed limited craniotomy, a small cortical opening (10-20 mm), a precise trajectory to the foramen of Monro, and standard microsurgical instruments. Stereotactic transventricular microsurgical resection provided safe and effective management of patients with colloid cysts, even in the absence of hydrocephalus.

Adolescent↗

PubMed2001

Polysaccharide colloidal particles as delivery systems for macromolecules.

Mucosal delivery of complex molecules such as peptides, proteins, oligonucleotides, and plasmids is one of the most intensively studied subjects. The use of colloidal carriers made of hydrophilic polysaccharides, i.e. chitosan, has arisen as a promising alternative for improving the transport of such macromolecules across biological surfaces. This article reviews the approaches which have aimed to associate macromolecules to chitosan in the form of colloidal structures and analyzes the evidence of their efficacy in improving the transport of the associated molecule through mucosae and epithelia. Chitosan has been shown to form colloidal particles and entrap macromolecules through a number of mechanisms, including ionic crosslinking, desolvation, or ionic complexation, though some of these systems have been realized only in conjunction with DNA molecules. An alternative involving the chemical modification of chitosan has also been useful for the association of macromolecules to self-assemblies and vesicles. To date, the in vivo efficacy of these chitosan-based colloidal carriers has been reported for two different applications: while DNA-chitosan hybrid nanospheres were found to be acceptable transfection carriers, ionically crosslinked chitosan nanoparticles appeared to be efficient vehicles for the transport of peptides across the nasal mucosa. The potential applications and future prospects of these new systems for mucosal delivery of macromolecules are highlighted at the end of the chapter.

Administration, Intranasal↗

PubMed2001

Numerical modeling of humic colloid borne americium (III) migration in column experiments using the transport/speciation code K1D and the KICAM model.

The humic colloid borne Am(III) transport was investigated in column experiments for Gorleben groundwater/sand systems. It was found that the interaction of Am with humic colloids is kinetically controlled, which strongly influences the migration behavior of Am(III). These kinetic effects have to be taken into account for transport/speciation modeling. The kinetically controlled availability model (KICAM) was developed to describe actinide sorption and transport in laboratory batch and column experiments. Application of the KICAM requires a chemical transport/speciation code, which simultaneously models both kinetically controlled processes and equilibrium reactions. Therefore, the code K1D was developed as a flexible research code that allows the inclusion of kinetic data in addition to transport features and chemical equilibrium. This paper presents the verification of K1D and its application to model column experiments investigating unimpeded humic colloid borne Am migration. Parmeters for reactive transport simulations were determined for a Gorleben groundwater system of high humic colloid concentration (GoHy 2227). A single set of parameters was used to model a series of column experiments. Model results correspond well to experimental data for the unretarded humic borne Am breakthrough.

Americium↗

PubMed2002

Contaminant transport in dual-porosity media with dissolved organic matter and bacteria present as mobile colloids.

In riverbank filtration, contaminant transport is affected by colloidal particles such as dissolved organic matter (DOM) and bacterial particles. In addition, the subsurface heterogeneity influences the behavior of contaminant transport in riverbank filtration. A mathematical model is developed to describe the contaminant transport in dual-porosity media in the presence of DOM and bacteria as mobile colloids. In the model development, a porous medium is divided into the mobile and immobile regions to consider the presence of ineffective micropores in physically heterogeneous riverbanks. We assume that the contaminant transport in the mobile region is controlled by the advection and dispersion while the contaminant transport in the immobile region occurs due to the molecular diffusion. The contaminant transfer between the mobile and immobile regions takes place by diffusive mass transfer. The mobile region is conceptualized as a four-phase system: two mobile colloidal phases, an aqueous phase, and a solid matrix. The complete set of governing equations is solved numerically with a fully implicit finite difference method. The model results show that in riverbank filtration, the contaminant can migrate further than expected due to the presence of DOM and bacteria. In addition, the contaminant mobility increases further in the presence of the immobile region in aquifers. A sensitivity analysis shows that in dual-porosity media, earlier breakthrough of the contaminant takes place as the volumetric fraction of the mobile region decreases. It is also demonstrated that as the contaminant mass transfer rate coefficient between the mobile and immobile regions increases, the contaminant concentration gradient between the two regions reverses at earlier pore volumes. The contaminant mass transfer coefficient between the mobile and immobile regions mainly controls the tailing effect of the contaminant breakthrough. The contaminant breakthrough curves are sensitive to changes in contaminant adsorption and desorption rate coefficients on DOM and bacteria. In situations where the contaminant is released in the presence of DOM and bacteria in dual-porosity media, the early breakthrough and tailing occur due to the colloidal facilitation and presence of immobile regions.

Adsorption↗

PubMed2001

Sorption behaviour of Am on marl groundwater colloids.

The sorption of americium on marl colloids is studied in a comprehensive way. In Na-HCO3 groundwater conditions, americium in the concentration range 3 x 10(-11)-3 x 10(10) M sorbs onto groundwater colloids. In these tests, the colloid concentration is rather high, i.e. Ccoll 1.7+/-1.3 mg l(-1) for sizes 505000 nm or Ncoll (1.7+/-0.1) x 10(11) l(-1) for sizes larger than 100 nm. These colloids are mainly chlorite and smectite/illite with an average size smaller than 500 nm. For the groundwater (pH 8.6, [Na+]-[HCO3]-2 x 10(-2) M), Kd values in the range 1-3 x 10(6)mlg(-1) are measured. These values are compared with experimental and modelled values reported earlier in the literature.

Absorption↗

PubMed2004

Importance of colloids in the transport within the dissolved phase (<450 nm) of artificial radionuclides from the Rhône river towards the Gulf of Lions (Mediterranean Sea).

The significance of colloidal fractions regarding the transport of artificial radionuclides in natural water systems is underlined by using sequential ultrafiltration both in the Rhône freshwater and the marine area under and outside the influence of the river outflow. Indeed, the Rhodanian aquatic system represents an interesting test site as various artificial radionuclides are released into the Rhône river by several nuclear installations. We focused our study on (137)Cs, (106)Ru, (60)Co, (238)Pu and (239+240)Pu. Our results show that Fe, Al and Organic carbon (OC) are the main components of colloidal matter. Colloids represent about 15% of dissolved (<450 nm) OC and 25% of dissolved Fe and Al exported towards the sea. Within the dissolved (< 450 nm) phase, these colloidal compounds are shown to account for the transport of 40% for both Co and Ru, 60% for (238)Pu and (239+240)Pu and have no significance on (137)Cs flux.

Colloids↗

PubMed1985

Myocardial perfusion imaging in humans by contrast echocardiography using polygelin colloid solution.

This study evaluated the myocardial contrast effect and safety of polygelin colloid solution selectively injected into the coronary arteries in 25 patients during two-dimensional echocardiography. Six patients (group I) had selective intracoronary injections of nonagitated and 19 (group II) of hand-agitated polygelin colloid solution. Myocardial contrast was seen on two-dimensional echocardiographic cross sections in three patients of group I and in all patients of group II; in 16 patients it was also seen on M-mode echocardiograms. The contrast effect lasted for 15 to 60 seconds. The intensity of myocardial opacification was not significantly influenced by the amount of polygelin colloid solution injected, heart rate or cardiac size. The total number of contrast-enhanced segments after right and left coronary artery injections delineated the entire cross-sectional area in any given view. None of the patients developed symptoms during or immediately after the injections. One patient had transient second degree atrioventricular block after a right coronary wedge injection, one patient showed a QRS axis shift and two others had transient T wave changes. There were no aortic blood pressure changes and no significant serum enzyme (creatine kinase [CK], CK-MB fraction, glutamic oxaloacetic transaminase) elevation or alterations of left ventricular function assessed echocardiographically. It is concluded that hand-agitated polygelin colloid solution is a useful and safe intracoronary contrast agent for delineating myocardial perfusion areas on two-dimensional echocardiography in humans.

Adolescent↗

PubMed1999

An in-vitro assessment of a NanoCrystal beclomethasone dipropionate colloidal dispersion via ultrasonic nebulization.

Short duration ultrasonic nebulization of a concentrated NanoCrystal colloidal dispersion of beclomethasone dipropionate demonstrated an increased respirable fraction and decreased throat deposition when evaluated in an Andersen 8-stage cascade impactor in comparison to the commercially available propellant-based product Vanceril. An aqueous-based 1.25% w/w colloidal dispersion of beclomethasone dipropionate when aerosolized via an Omron NE-U03 ultrasonic nebulizer generated a respirable drug dose from 22.6 to 39.4 micrograms per 2 s actuation period, compared to 12.8 micrograms for a single actuation of Vanceril. When viewed as a percentage of the emitted dose (through the actuator or mouthpiece), the respirable fraction ranged from 56 to 72% for the nanocrystalline formulation versus 36% for the propellant system. In addition, the throat deposition as seen in the induction port was 9-10% of the emitted dose for the novel suspension, as compared to 53% for the commercial product. Thus, when used with the device outlined herein, a nanocrystalline colloidal suspension of beclomethasone dipropionate affords greater potential drug delivery to the conductive airways of the lung in both quantity and as a percent of emitted dose. Additionally, lower potential throat deposition values were observed which may retard the development of undesirable side effects, such as candidiasis, when compared to a propellant based delivery system. Lastly, the ability to atomize aqueous-based nanocrystalline colloidal dispersions represents an environmentally sound alternative to the current chlorofluorocarbon (CFC)-based products and may avoid the technical difficulties of reformulating with chlorine-free propellants.

Aerosols↗

PubMed1998

Increasing the colloid osmotic pressure of cardiopulmonary bypass prime and normothermic blood cardioplegia minimizes myocardial oedema and prevents cardiac dysfunction.

UNLABELLED: Our recent work demonstrated that normothermic continuous antegrade blood cardioplegia results in cardiac dysfunction related to myocardial oedema. This oedema was partially due to increased myocardial microvascular fluid filtration induced by crystalloid hemodilution. We hypothesized that increasing the colloid osmotic pressure of blood cardioplegia would stop fluid filtration into the cardiac interstitium, thus preventing myocardial oedema and cardiac dysfunction. METHODS: We determined myocardial water content in six dogs by microgravimetry and myocardial lymph flow from the major prenodal cardiac lymphatic. Preload recruitable stroke work was derived from sonomicrometry and micromanometry. The dogs were subjected to normothermic cardiopulmonary bypass primed with 6% hetastarch and 1 h of normothermic continuous antegrade blood cardioplegia (4:1 blood:6% hetastarch colloid osmotic pressure 21 +/- 2 mmHg) delivered at 50 mmHg perfusion pressure. RESULTS: We found that despite increased colloid osmotic pressure, a small but significant increase in myocardial water content still occurred during blood cardioplegia. As myocardial lymph flow virtually ceased during cardioplegia, myocardial microvascular filtration must have been present. However, increased myocardial lymph flow following cardioplegia resulted in complete oedema resolution associated with normal left ventricular performance post-cardiopulmonary bypass. CONCLUSIONS: Our data show that the plegic myocardium is prone to oedema formation because of both relatively enhanced fluid filtration and lymph flow cessation. We conclude that increasing the colloid osmotic pressure of normothermic blood cardioplegia minimizes myocardial oedema, thus preventing post-cardiopulmonary bypass cardiac dysfunction.

Animals↗

PubMed2000

Preparation and evaluation of samarium (III) phosphate [(153)Sm] colloid (SMPC) for possible therapeutic use.

A simple method of preparation of a new therapeutic colloid, samarium(III) phosphate-(153)Sm (SMPC), is reported involving the reaction of carrier-added (153)SmCl(3) with phosphoric acid. Recovery of the colloid was accomplished by dialysis leading to purification and a radiochemical (RC) yield of more than 90%. The RC purity of purified colloid formulated in isotonic phosphate buffer was more than 99% as assessed by paper chromatography. The product retained its RC purity throughout the period of stability study of 7 days. Complete retention of radioactivity instilled in the rabbit knee joint was observed over the study period of 6 days, with radioactivity in the blood being indistinguishable from the natural background activity. Ninety-six percent of colloidal particles were in the size range of 0.3-2 microm. The promising results demonstrated warrant further studies on SMPC for assessing the suitability for therapy.

Animals↗

PubMed2006

Lectin-recognizable colloidal dispersions stabilized by n-dodecyl beta-D-maltoside: particle-particle and particle-surface interactions.

Recently, we reported that it is possible to utilize sugars as stabilizing agents for colloidal particles. This study shows that when n-dodecyl beta-D-maltoside (DDM) is utilized as a dispersing and stabilizing agent in the synthesis and stabilization of poly[methyl methacrylate-co-(n-butyl acrylate)] (p-MMA/nBA) colloidal particles, stable colloidal dispersions can be formed. Since understanding of sugar-protein interactions have numerous practical and scientific implications, these studies examine DDM-stabilized p-MMA/nBA colloidal particles and their specific binding properties with concanavalin A (Con A). By use of spectroscopic analysis, unique binding characteristics that are a function of DDM concentration, time, and the concentration of Con A are detected. When DDM-stabilized p-MMA/nBA particles are allowed to coalesce, DDM is released from the particle surfaces and, under suitable conditions, selectively stratifies in the areas of the excess of interfacial energy near the film-air (F-A) interface, thus providing sites for attracting Con A via alpha-glucose-OH hydrogen bonding. Consequently, adsorption of Con A at the F-A interfaces occur and the degree of adsorption is controlled by the amount of DDM at the F-A interface.

Adsorption↗

PubMed2002

Characterization of Gorleben groundwater colloids by atomic force microscopy.

Groundwater colloids from the Gorleben site (Lower Saxony, Germany) are characterized in the presence of Eu(III) by tapping-mode atomic force microscopy (AFM) with phase contrast imaging. Using a liquid cell the method allows investigations of samples being in contact with aqueous solution. This ensures that complex structures are kept in their native hydrated state. Different types of colloids and aggregates are found by AFM, e.g., spherical particles, fibrous structures, and structures which appear to be hollow. A partial coating of the edges of clay particles with humic colloids can be assumed from phase contrast images. Therefore, aquatic colloids and their aggregates found in Gorleben groundwater can be characterized as a complex mixture of components, which may influence the migration of groundwater contaminants in different processes.

Colloids↗