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PubMed2003

Osmotic force resisting chain insertion in a colloidal suspension.

We consider the problem of inserting a stiff chain into a colloidal suspension of particles that interact with it through excluded volume forces. The free energy of insertion is associated with the work of creating a cavity devoid of colloid and sufficiently large to accommodate the chain. The corresponding work per unit length is the force that resists the entry of the chain into the colloidal suspension. In the case of a hard sphere fluid, this work can be calculated straightforwardly within the scaled particle theory; for solutions of flexible polymers, on the other hand, we employ simple scaling arguments. The forces computed in these ways are shown, for nanometer chain and colloid diameters, to be of the order of tens of pN for solution volume fractions of a few tenths. These magnitudes are argued to be important for biophysical processes such as the ejection of DNA from viral capsids into the cell cytoplasm.

Capsid↗
PubMed2006

Colloids on free-standing smectic films.

We study the structure of a free-standing smectic-A film around a micron-size polystyrene colloid adsorbed onto the film. We find that a colloid or a cluster of colloids is surrounded by an optically distinct and radially decorated meniscus ending with a sharp edge. The observed strong and finite-range attraction between the adsorbed colloids is driven by the fusion of menisci. We interpret the structure of the smectic meniscus in terms of a model dominated by the surface free energy and we argue that the characteristic appearance of the meniscus is due to layer undulations.

Adsorption↗
PubMed2006

Influence of a random field on particle fractionation and solidification in liquid-crystal colloid mixtures.

The influence of a random-anisotropy (RA) type disorder on the phase separation of nematogen-colloid mixtures is studied theoretically by combining the phenomenological Landau-de Gennes, Carnahan-Starling, and hard-sphere crystal theories. We assume that the colloids enforce the RA disorder on the surrounding thermotropic liquid-crystal (LC) molecules. We adopt the Imry-Ma argument according to which the lower-temperature phase exhibits a domain-type pattern. The colloids impose a finite degree of orientational ordering even in the isotropic (paranematic) phase. In the ordered phase they give rise to a domain-type structure, resulting in the distorted nematic (speronematic) phase. The RA field opposes the phase separation tendency. With increasing disorder the difference between the paranematic and speronematic ordering decreases. Consequently there is a critical disorder, above which both phases become identical from the orientation point of view, but have different concentrations of colloids. We have also estimated another characteristic value of disorder above which the isotropic phase can exist only in a liquid state, the crystal phase being suppressed completely.

Anisotropy↗
PubMed1995

Mechanism of colloidal particle uptake into the lymphatic system: basic study with percutaneous lymphography.

PURPOSE: To examine the extracellular (dispersed particles) and intracellular (phagocytosed particles) colloidal particle transport from subcutaneous tissue into the lymphatic system. MATERIALS AND METHODS: Perfluorocarbon emulsions LA11063 (mean particle diameter, 0.34 micron) and ZY12149 (mean particle diameter, 0.06 micron) were individually injected into the dorsal skin of the hind foot of rabbits. Lymph flow rates and particle concentrations were determined in prenodal lymph fluid after injection, with and without massage of the skin over the injection site. RESULTS: In the first 24 hours after injection, extracellular colloid flux was substantially larger than intracellular flux. Lymph flow rates and colloid concentrations increased substantially with massage. Extracellular LA11063 flux was smaller than ZY12149 flux, whereas intracellular LA11063 flux exceeded ZY12149 flux. CONCLUSION: Transport of colloids into lymphatic vessels is dependent on particle size. Both extracellular and intracellular pathways are utilized. External tissue movement contributes substantially to the rate of particle uptake via both pathways.

Animals↗
PubMed1998

Lymphoscintigraphic identification of sentinel lymph nodes: clinical evaluation of 0.22-micron filtration of Tc-99m sulfur colloid.

PURPOSE: To evaluate the use of 0.22-micron filtration of technetium-99m sulfur colloid particles in the optimization of lymphoscintigraphy. MATERIALS AND METHODS: Forty-one consecutive lymphoscintigraphic studies obtained with 0.22-micron filtration of Tc-99m sulfur colloid in 41 patients (26 men, 15 women; average age, 55.4 years) and 41 consecutive studies obtained with 5.0-micron filtration in 41 patients (20 men, 21 women; average age, 54.5 years) were retrospectively, randomly reviewed. Studies were evaluated for lymphatic channel depiction and sentinel lymph node depiction. Studies included immediate flow images (obtained at 10 seconds per frame) and multiview static images obtained up to 2 hours after intradermal Tc-99m sulfur colloid injection. RESULTS: The number of drainage beds visualized was 52 with 5.0-micron filtration and 51 with 0.22-micron filtration (P = .570). The number of lymphatic channels visualized was 45 with 5.0-micron filtration and 75 with 0.22-micron filtration (P = .006). The number of lymph nodes visualized was 102 with 5.0-micron filtration and 123 with 0.22-micron filtration (P = .123). The number of studies judged as optimal (i.e., depicted lymphatic channels leading to sentinel nodes) was 10 with 5.0-micron filtration and 19 with 0.22-micron filtration (P = .038). The number of studies with depicted lymph nodes but no depicted lymphatic channel was 15 with 5.0-micron filtration and six with 0.22-micron filtration (P = .023). CONCLUSION: The use of 0.22-micron filtration in the preparation of Tc-99m sulfur colloid substantially improves study quality and increases the diagnostic certainty in the identification of sentinel lymph nodes.

Female↗
PubMed1996

Interstitial fluid, plasma protein, colloid, and leukocyte uptake into initial lymphatics.

Lymphatics serve to remove from the interstitium a range of materials, including plasma proteins, colloid materials, and cells. Lymph flow rates can be enhanced by periodic tissue compression or venous pressure elevation, but little is known to what degree enhancement of lymph flow affects material transport. The objective was to examine the uptake of plasma proteins, a colloidal perflubron emulsion (LA-11063, mean particle diameter = 0.34 micron), and leukocytes into lymphatics. Prenodal collecting lymphatics in the lower hindlimb of rabbits were cannulated with and without foot massage and after elevation of venous pressure (40 mmHg). The average lymph flow rates were elevated approximately 22-fold by the skin massage but only about threefold by venous pressure elevation. Lymph-to-plasma protein concentration ratio remained unchanged by the massage but decreased significantly after venous pressure elevation. Lymph colloid concentration and leukocyte counts were elevated on average 47 and 8.5 times, respectively, by foot massage, but both decreased after venous pressure elevation. These results suggest that skin movement by massage and elevation of the venous pressure lead to opposite lymph transport kinetics of protein, colloids, and cells. Massage is more effective to enhance material transport out of the interstitium into the initial lymphatics.

Animals↗
PubMed1998

Stereotactic cyst wall disruption and aspiration of colloid cysts of the third ventricle.

BACKGROUND: Current strategies of surgical therapy for colloid cysts have been associated with low rates of initial success and high rates of morbidity, mortality and recurrence of cysts. Cyst recurrence following simple stereotactic aspiration has been hypothesized to be due to regrowth of the epithelium composing the cyst wall. METHODS: We propose a procedure involving stereotactic disruption of the colloid cyst wall with the removal of a portion of the cyst wall followed by aspiration of cyst contents as a surgical therapy for colloid cysts. RESULTS: This procedure was performed in 2 female and 3 male patients who were followed for an average of 49 months with all patients demonstrating immediate improvement of symptoms and resolution of the cyst verified with repeat computerized tomography (CT) scans. There was one incidence of recurrence in an asymptomatic patient at 75 months postoperatively. CONCLUSION: We propose that stereotactic partial cyst wall disruption and content aspiration may limit recurrence of colloid cysts, thus offering an advantage over simple stereotactic aspiration alone.

Adult↗
PubMed1995

Long-term high-colloid oncotic therapy for ischemic brain edema in gerbils.

BACKGROUND AND PURPOSE: We evaluated the effects of long-term administration of high-colloid oncotic pressure on ischemic brain edema in Mongolian gerbils. METHODS: Animals that exhibited stroke after 35 minutes of unilateral forebrain ischemia were used. The gerbils were divided into albumin- (1 g/kg body wt, 25% albumin; n = 30) and saline-injected (4 mL/kg; n = 30) groups. Both agents were administered intravenously every 12 hours starting immediately after the recirculation. Plasma colloid oncotic pressure, serum sodium and potassium concentrations, and brain water, sodium, and potassium content were measured 24, 48, and 72 hours after recirculation. RESULTS: Plasma colloid oncotic pressure at 24, 48, and 72 hours after recirculation was significantly higher in the albumin- (26.1 +/- 2.3 mm Hg) than in the saline-treated group (18.5 +/- 1.9 mm Hg; P < .01), and brain water content of the ischemic hemisphere was significantly lower in the albumin group (79.5%, 80.2%, and 80.5%, respectively) than in the saline group (80.9%, 81.6%, and 82.1%, respectively; P < .05) at all three time points. Brain sodium content at 24 hours was significantly lower in the albumin than in the saline group (P < .05), while brain potassium content at 24 and 48 hours was significantly higher in the albumin than in the saline group (P < .05). The changes in brain water and sodium plus potassium content, which were calculated from differences between the ischemic and nonischemic hemispheres, showed a significant correlation in both groups (P < .01), but there was no significant difference between the linear regression lines for both groups. CONCLUSIONS: Long-term high-colloid oncotic pressure was effective in treating ischemic brain edema, probably acting by diminishing the bulk flow through the disrupted blood-brain barrier and ameliorating the vasogenic edema.

Albumins↗
PubMed1995

Coadsorption of IgG and BSA onto sulfonated polystyrene latex: II. Colloidal stability and immunoreactivity.

The present work deals with the study of the colloidal stability and immunoreactivity of sulfonated polystyrene latex particles covered by different amounts of m-BSA and IgG/a-CRP. These proteins have been previously adsorbed onto a sulfonated latex by sequential and competitive coadsorption experiments and it was possible to obtain latex-protein particles with different degrees of coverage by each protein. The latex particles, fully or partially covered by each protein (termed latex-protein complexes), were resuspended under several conditions (different pH and ionic strength values) and their colloidal stability, vs the addition of the electrolyte was studied using turbidity measurements. This stability appeared at a high degree of coverage by BSA and at a pH in which the BSA was negatively charged. At a high degree of coverage by IgG, the latex particles were unstable at all pHs. As a final part of this work, the immunoreactivity of several complexes was studied following the changes in the turbidity after the addition of CRP antigen. Only the complexes which were colloidally stable gave detectable reactivity. However, the complexes with a relatively low degree of coverage by IgG/a-CRP gave good immunoreactivity. Therefore, the latex-protein complex properties depended on the percentage of BSA or IgG adsorbed and on the electric state of the proteins at the redispersion pH. Under specific incubation conditions, sulfonated latex covered by significant IgG/BSA percentages was obtained, which showed a high colloidal stability and good immunoreactivity.

Adsorption↗
PubMed2005

Synthesis of solvent-stabilized colloidal nanoparticles of platinum, rhodium, and ruthenium by microwave-polyol process.

Solvent-stabilized Pt, Rh, and Ru colloidal nanoparticles were synthesized by a microwave-polyol process. They were characterized by TEM and XPS, XRD, and UV-vis examination. These colloids have small particle sizes with narrow size distribution, and they were stable in glycol upon storage under ambient condition for months. Separation and XPS characterization of the intermediate colloids demonstrated the two-step mechanism for the formation of solvent-stabilized metal colloids via hydrolysis.

Colloids↗
PubMed1984

Colloids vs. crystalloids--a continuing controversy.

The crystalloid vs. colloid controversy is based on a disagreement as to the most effective, safest, and most economical method of maintaining an effective plasma volume in shock patients. This review discusses Starling's law of fluid movement, with a definition of each term in the normal physiological state, and presents examples of how each component of Starling's law differs in the two major types of pulmonary edema: (1) cardiogenic and (2) noncardiogenic. The colloid-crystalloid literature is reviewed briefly with an emphasis on the major studies that support each side, and the deficiencies in each study. The arguments supporting each side of the crystalloid-colloid debate are then listed, with a summary that demonstrates the areas of agreement between the two schools of thought on fluid resuscitation. Each major colloid (albumin, dextran, hetastarch) and a representative crystalloid (lactated Ringer's) are discussed in terms of their chemistry; pharmacology and indications; and precautions, adverse reactions, and side effects. A table is included that summarizes the available products' data regarding composition, volume expansion, duration of expansion, half-life, metabolism, elimination, precautions, adverse reactions, and dose.

Blood Proteins↗
PubMed2003

Acute intravascular volume expansion with rapidly administered crystalloid or colloid in the setting of moderate hypovolemia.

UNLABELLED: Although the distribution of various crystalloid and colloid solutions at equilibrium has been well established, the acute peak expansion of intravascular volume that can be achieved with the rapid administration of crystalloid or colloid is unknown. We studied eight healthy male subjects in a two-part crossover trial designed to assess the maximal increase in intravascular volume achieved with 1000 mL of lactated Ringer's solution compared with the same volume of 6% Hetastarch. Subjects were made moderately hypovolemic by the withdrawal of 900 mL of blood, and then the crystalloid or colloid solution was rapidly infused over 5-7 min. Serial dilution of hematocrit was measured every 5 min for 30 min to determine changes in blood volume. Peak expansion of intravascular volume with lactated Ringer's solution was 630 +/- 127 mL, occurring immediately the rapid infusion was complete, whereas the peak expansion of intravascular volume with 6% Hetastarch was 1123 +/- 116 mL and occurred 5 min after the completion of the fluid infusion. The results were significantly different (P < 0.001). These results would suggest that even for very short periods of time, rapid infusion of colloid significantly more effectively increases blood volume and, by inference, cardiac output than the same volume of crystalloid, even if the crystalloid is administered very rapidly. IMPLICATIONS: Under conditions of moderate hypovolemia, the maximal acute intravascular volume expansion with the rapid infusion of 1000 mL of lactated Ringer's solution is slightly more than half that achieved with the same volume of 6% Hetastarch.

Adult↗
PubMed2006

A head-to-head comparison of the in vitro coagulation effects of saline-based and balanced electrolyte crystalloid and colloid intravenous fluids.

Both fluid composition (e.g., type of hydroxyethyl starch) and formulation (e.g., saline or balanced salt carrier solution) may alter whole blood coagulation. We therefore enrolled 10 healthy volunteers to test ex vivo, thrombelastograph-based blood coagulation differences of eight crystalloid and colloid solutions at 20%, 40%, and 60% dilutions. Saline and lactated Ringer's solution produced a hypercoagulable state at 20%-40% dilutions. Saline, hetastarch in saline, pentastarch in saline, tetrastarch in saline, and human albumin solutions all produced a hypocoagulable state at 60% dilution. Hetastarch in saline also produced a hypocoagulable state at 40% dilution. The larger molecular weight starches produced more intense coagulation abnormalities than the medium molecular weight compounds formulated similarly (i.e., suspended in saline or balanced salt solution). The balanced salt solutions caused fewer coagulation abnormalities, especially pentastarch in balanced salt solution. This balanced salt pentastarch preparation produced the least derangement of coagulation of the colloid solutions at all dilutions, causing hypercoagulability at the lower dilutions and minimal coagulation derangement at 60% dilution. These data support the theory that smaller molecular weight hydroxyethyl starches and colloids suspended in balanced salt solutions preserve coagulation better than large molecular weight starches and saline-based colloids, as judged by thrombelastography.

Analysis of Variance↗
PubMed2000

Local thrombus formation in the site of intravenous injection of chlorpromazine: possible colloid-osmotic lysis of the local endothelial cells.

Since amphiphilic drugs are known to interact with biomembranes, we investigated local vessel damage and thrombosis which might be brought about by intravenous dosing using chlorpromazine (CPZ) as a representative compound. CPZ-induced hemolysis was suppressed by an increase in sucrose concentration in the medium, characterizing this hemolysis to be colloid-osmotic lysis, which includes the enhancement of membrane phospholipid fluidity and consequent small pore formation in the membranes. This was supported by the observation that hemolysis by filipin, not featuring the stage of small pore formation, was not affected by sucrose. [14C]Glucose-entrapping liposomes were degraded by CPZ, and this degradation was enhanced by an increase in the intravesicle glucose concentration. These results indicated that the compound could induce colloid-osmotic lysis in erythrocytes and artificial membrane vesicles. CPZ also injured cultured porcine aortic endothelial cells (PAEC), as evidenced by lactate dehydrogenase (LDH) leakage. This injury was also suppressed by increase in sucrose concentration in the medium, suggesting that colloid-osmotic lysis again occurred. When rats were intravenously injected with CPZ, local endothelial cell (EC) injury and associated thrombus formation were observed, suggesting that CPZ's action was also evident in vivo. To our knowledge, this is the first finding which suggests that an intravenously dosed amphiphilic drug can injure local ECs based on a colloid-osmotic lysis mechanism leading to thrombosis.

Animals↗
PubMed1997

[An importance of colloid chemical characterization of liposomes for DDS in a large scale production].

Efficacy and safety data of liposomal drugs in a laboratory environment are often not reproduced on an industrial production scale. This is largely due to the fact that the colloid-chemical properties of the liposomes manufactured on a small scale are not reproduced in large scale production. Though the size and the electric charge of liposomes are measured and are adequately specified in relation to the bio-distributions in most developments of liposomes (1), uniformity of lipid components, exposure of bio-chemically important functional groups on the outer surface of liposomes (2), fixed aqueous layer thickness (FALT), number of the lipid bilayers, etc., are dependent upon the scale of production. Nevertheless these properties are not always exactly specified. Uniformity, especially of the functional groups on the membrane surface can be assessed chemically or bio-chemically with fractionated samples, and FALT can be easily determined through electro-chemical means (3). In this review, colloid chemical characterization of liposomes is introduced, FALT as an example, and its importance in a quality control of a liposomal product in an industrial scale production is shown. Methoxy-polyethyleneglycol-diacylglycerol (PEG-DAG) with varying PEG chain length and acyl chains were synthesized, FALT of liposomes coated with PEG-DAG determined and tissue distribution in tumor bearing mice. The higher incorporation ratio of PEG-DAG into liposomal membrane was observed with PEG-DAG with short acyl chains (myristoyl) and a small PEG molecular weight (1000). The easier to incorporate, the easier to be stripped in the serum. The disposition data in the rats well reflected the colloid chemical and in vitro data of the PEG liposomes. Galactosyl-carbonyl-propionyl-polyethyleneglycol-diacylglycerol (Gal-PEG-DAG) with oxyethylene number, n = 10, 20 and 40 were synthesized. The exposure of the galactose residue beyond the fixed aqueous layer of liposomes coated with Gal-PEG-DAG was monitored by a lectin, Ricinus communis agglutinin (RCA) induced agglutination, the half life in the blood after i.v. injection into rats, organ distribution determined and intrahepatic distribution studied. Only the liposomes containing the Gal-PEG10-DAG aggregated with the lectin, indicating that only with this derivative the galactose group was adequately exposed. The Gal-PEG10-DAG liposomes were cleared from the plasma with a half life of 0.3 h. The plasma elimination could be attributed entirely to increased uptake by the liver. The increased liver uptake was almost entirely attributed to increased uptake by the non-parenchymal cell. Incorporation of PEG-DSPE in to the Gal-PEG10-DAG liposomes caused 1) a three-fold increase in blood circulation time, 2) a small but significant decrease in hepatic uptake after 20 h and 3) a significant shift in intrahepatic distribution in favor of the hepatocytes, comparable to that of the control liposomes. In conclusion, therapeutic efficacy and safety of liposomes can be controlled by their colloid chemical, more exactly, surface chemical properties. By setting up reasonable quality control specification of the properties in laboratory and examining the specifications satisfied in upscaling, the efficacy and safety are reproduced in a large scale product.

Animals↗
PubMed1981

Changes in renal cortical sialic acids and colloidal iron staining associated with exercise.

The purpose of this study was to determine if exercise was associated with alterations in renal cortical sialic acid content or glomerular capillary anionic character. These factors have been shown to be important, insofar as they contribute to an electrostatic barrier which prevents the filtration of negatively charged macromolecules. In unilaterally nephrectomized dogs (n=7), exercised kidneys tended to have increased amounts of sialic acids and a decrease in glomerular anionic character, as evaluated by the intensity of colloidal iron staining, however, nephrectomy alone also caused similar changes. Additional experiments were conducted using rat litter mates assigned to control or treadmill-exercise groups. Exercised animals were run for 60-80 min. Renal cortical sialic acids were 2.74 +/- 0.07 mumol/g for controls (n=12) and 3.03 + 0.09 mumol/g for the exercised animals (n=10) (P less than 0.05). Colloidal iron staining, rated on a 0-3 scale (0=no uptake, 3=maximum staining) was 2.5 +/- 0.1 and 1.3 +/- 0.3 for the controls and exercised animals, respectively (P less than 0.05). Colloidal iron staining remained below control levels for 24 h post-exercise. These data suggest that exercise increases glomerular sialic acid content and decreases colloidal iron staining. This latter effect may decrease the glomerular capillary electrostatic barrier and thereby may be an important factor in causing exercise proteinuria.

Animals↗
PubMed2004

C18-modified metal-colloid substrates for surface-enhanced Raman detection of trace-level polycyclic aromatic hydrocarbons in aqueous solution.

Metal colloids immobilized on a glass support substrate are modified with a self-assembled alkylsilane (C18) layer to promote adsorption of polycyclic aromatic hydrocarbons from aqueous solutions. Detection of these compounds from low concentration solutions is accomplished by using surface-enhanced Raman scattering (SERS). SERS spectra of pyrene adsorbed to C18-modified immobilized silver colloids are dominated by Raman bands that are not consistent with pyrene and indicate that pyrene undergoes a chemical reaction at the surface. The origins of this surface product are investigated, and it is determined that silver and oxygen are required to form the product, whose Raman spectrum is consistent with oxidation to a quinone. When a C18-modified gold-colloid substrate is used, Raman scattering consistent with unreacted pyrene is observed. The adsorption and detection of pyrene adsorbed from low (2 ppb) concentration aqueous solutions onto C18-modified gold-colloid substrates is reported; naphthalene and phenanthrene are detected at approximately 5 ppb. Adsorption kinetics are rapid (<5 min), and the concentration-dependent SERS response is consistent with a Langmuir isotherm.

Colloids↗
PubMed2005

Surface-enhanced Raman spectra of calf thymus DNA adsorbed on concentrated silver colloid.

Raman and surface-enhanced Raman scattering (SERS) spectra of calf thymus DNA were investigated. We have carried out improvements to the silver colloid preparation method of Lee and Meisel in two respects. In one method, the silver sol was boiled with rapid stirring for over two hours. In the second method, the silver sol was concentrated by centrifugation before adding it to the DNA solution. The resulting hydrosol could be stored for 15 months because of its high stabilization. Structural information with respect to the phosphate backbone, deoxyribose, and four bases of DNA could be obtained before and after the DNA solutions were added to the concentrated Ag colloid substrate. The intensities of almost all characteristic bands assigned to various groups of the components of DNA were enhanced to a remarkable degree. The enhancement effect of the DNA solution at neutral pH 7.0 was obviously much better than that at acidic pH 3.4 or at alkaline pH 8.5. Intensity increases of the SERS bands of the DNA solution with time were observed. The SERS signals obtained 16 hours after the interaction of the Ag colloid with the DNA solution were much better than the SERS signals obtained just after the mixed liquid was prepared. This method can be widely used to store the Ag colloid for long times and to obtain the SERS spectra of DNA molecules, and it can further be used to study the adsorption behavior of solute biomacromolecules in different solvents.

Adsorption↗