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PubMed1982

The significance of colloid osmotic pressure measurement after crystalloid and colloid infusions.

Colloid osmotic pressure (COP) was followed postoperatively in 55 randomized patients. After minor operations and short-term infusion therapy only small changes of the COP could be observed and it was concluded that after such operations COP measurement is unnecessary. After major surgical interventions, however, COP measurement gave valuable hints. It was shown that even in the case of moderate blood loss replaced by crystalloids an abnormally low COP did not occur. The same applied also to preoperative hemodilution. It was unnecessary to substitute the withdrawn blood with a colloid solution. In addition, COP measurement helped to avoid expensive albumin administrations, and indicated colloid overload in cases of pulmonary edema.

Adult↗
PubMed1996

Isolation and measurement of colloids in human plasma by membrane-selective flow field-flow fractionation: lipoproteins and pharmaceutical colloids.

Using a modified flow field-flow fractionation (flow FFF) technique termed membrane-selective flow FFF, a capability is developed to isolate various colloidal constituents that are naturally present in or may be introduced into blood plasma. Once isolated, the colloids may be subject to quantitative measurement to provide relative amounts of the different constituents and the size distribution curve of each. The potential of the technique has been demonstrated by isolating and measuring (a) the lipoprotein fractions found in human blood plasma, (b) liposyn II pharmaceutical emulsion added at 2 mg/mL of plasma, and (c) amphotericin B colloidal dispersion (a drug delivery agent) added to plasma at 0.5 mg/mL.

Chemical Fractionation↗
PubMed1977

Clinical comparison of 99mTc-labeled preformed phytate colloid and sulfur colloid: concise communication.

An in vitro preformed colloid preparation of 99mTc-Sn-phytate was compared both qualitatively and quantitatively with a commercial 99mTc-sulfur colloid kit in 30 patients. The degree of liver and spleen deposition of radiocolloid was, for practical purposes, the same. A slightly higher background was visually noted in 33% of the patients receiving preformed colloidal 99mTc-Sn-phytate, but it did not interfere with the diagnostic quality of the liver and spleen images. The only advantage of the phytate compound was a preparation time of less than 5 min.

Colloids↗
PubMed1999

Colloid Vibration Potential in a Concentrated Suspension of Spherical Colloidal Particles.

A relation between the dynamic electrophoretic mobility of spherical colloidal particles in a concentrated suspension and the colloid vibration potential (CVP) generated in the suspension by a sound wave is obtained from the analogy with the corresponding Onsager relation between electrophoretic mobility and sedimentation potential in concentrated suspensions previously derived on the basis of Kuwabara's cell model. The obtained expression for CVP is applicable to the case where the particle zeta potential is low, the particle relative permittivity is very small, and the overlapping of the electrical double layers of adjacent particles is negligible. It is found that CVP shows much stronger dependence on the particle volume fraction φ than predicted from the φ dependence of the dynamic electrophoretic mobility. It is also suggested that the same relation holds between the electrokinetic sonic amplitude of a concentrated suspension of spherical colloidal particles and the dynamic electrophoretic mobility. Copyright 1999 Academic Press.

Journal Article↗
PubMed1996

Colloid cyst of the third ventricle. Evaluation of 28 cases of colloid cyst of the third ventricle operated on by transcortical transventricular (25 cases) and transcallosal/transventricular (3 cases) approaches.

The clinical and x-ray features of 28 cases of colloid cyst of the third ventricle are described. Colloid cyst is one of the most favourable space-occupying lesions of the brain for successful surgical removal, because an exact pre-operative diagnosis is possible. The surgical approach for colloid cyst of the third ventricle is discussed and the frequency of postoperative seizure is reviewed in 28 cases and compared with the literature.

Adolescent↗
PubMed2000

Volume-term theories of phase separation in colloidal systems and long-range attractive tail in the pair potential between colloidal particles.

To explain the experimental observation that colloidal dispersion exhibits a "two-state" structure under certain conditions, Sogami and Ise (SI) proposed a model for an "effective" pair potential between colloidal particles which had an "attractive tail" more than a decade ago. The SI paper spawned several papers that dwelled on the shortcoming of the SI paper or strived to provide other explanations for the observed inhomogeneity of the suspension. We show herein that a long range attraction in the pair potential between colloidal particles is also obtained in "volume-term" theories in which the repulsive DLVO potential is retained.

Journal Article↗
PubMed1997

High pressure effects on the colloidal calcium phosphate and the structural integrity of micellar casein milk. Part 1. High pressure dissolution of colloidal calcium phosphate in heated milk systems.

Results of this study confirm that high temperature (118 degrees C/15 min) and high pressure (400 MPa/5 min) processing of skim milk, skim milk ultrafiltration and ultracentrifugation fractions, and model milk salt solutions cause dramatic shifts in their colloidal and soluble Ca phosphate equilibrium that affect their pH, dissolved Ca content, turbidity, and casein micelle microstructure. The relations between high temperature and high pressure processing-induced changes in the colloidal and soluble Ca phosphate equilibrium were evaluated in raw, pasteurized, and high temperature treated skim milk, ultrafiltration retentate and permeate of pasteurized skim milk, clear ultracentrifugation infranatant of pasteurized skim milk, and synthetic milk ultrafiltrates with and without lactose or Ca. The magnitude of the pH and dissolved Ca shifts caused by high temperature and high pressure processing was a function of casein micelle concentration. Ultrafiltration permeate exhibited the most drastic shits in pH and dissolved Ca contents due to high temperature and high pressure processing. Although high temperature processing reduced the pH of ultrafiltration permeate from 6.59 to 6.03 and the dissolved Ca from 100% to 58%, high pressure processing reversed both of these changes. These changes in high temperature and high pressure processed milk, milk fractions, and model milk salt solutions were related to microstructural changes in the casein micelles as revealed by electron microscopy.

Animals↗
PubMed1989

In vitro colloid osmotic pressure of commonly used plasma expanders and substitutes: a study of the diffusibility of colloid molecules.

The rational choice of a plasma substitute for states of hypovolaemia depends partly on its colloid osmotic pressure (COP). We have measured the COP of 108 samples of plasma substitute across selectively permeable membranes which retain molecules greater than 10,000 dalton (COP10) and 50,000 dalton (COP50) the ratio COP50/COP10 providing a potential index of diffusibility of the smaller molecules across capillary membranes. 6% Hespan solution showed a particularly favourable COP50/COP10 ratio at 0.58 indicating a potential for good retention in the circulation whilst 3.5% Haemaccel showed a COP50/COP10 ratio of 0.18 indicating a potential for marked transcapillary diffusion, especially in states of capillary leak. In patients with normal capillary permeability both Gelofusine and Dextran 110 are likely to show adequate retention in the circulation with a COP50/COP10 ratio of 0.37 and 0.39 respectively. These are comparable to the retention of 4.5% human albumin (0.36) but all of the plasma substitutes tested, with the exception of Haemaccel, provided a higher COP across both membranes than 4.5% human albumin solution. An in vivo comparison of these plasma substitutes is required to confirm the advantages of macromolecular colloids in states of capillary leak.

Colloids↗
PubMed1993

The effect of the type of colloid on the efficacy of hypertonic saline colloid mixtures in hemorrhagic shock: dextran versus hydroxyethyl starch.

Colloids increase and prolong the efficacy of hypertonic saline solutions in hemorrhagic shock. We compared the efficacy of dextran 60 and hydroxyethyl starch (HES) 200,000/0.5 at iso-oncotic concentrations of 6.5 or 6% in a 7.5% NaCI solution. Thirty-two rabbits were bled to maintain a mean arterial pressure at 35 mmHg. Twenty-five percent of the shed blood volume was replaced after 40 min by bolus infusion either with hypertonic dextran (HS-DEX) (n = 16) or with hypertonic hydroxyethyl starch (HS-HES) (n = 16). The animals were then observed for a 120-min period. In both groups immediate and complete restoration of cardiovascular function was achieved in up to 30 min and adequate restoration maintained for 60 min after infusion. During the subsequent 60 min signs of insufficient oxygen supply indicated the recurrence of near shock levels. Greater stability of hemodynamic efficacy was observed when dextran was added to hypertonic saline. The decrease in mean arterial pressure was lower in the dextran group (P < 0.05). The subsequent increase in avDO2 (v. cava sup.) was approximately 50% lower with dextran (1 ml/dl compared to 1.8 ml/dl); (P < 0.05). These differences occurred primarily within the initial 15 min although the differences in mean arterial pressure were recorded only after 30-60 min. A 50% reduction in lactate levels (1.1 compared to 2.0 mmol; P < 0.05) in immediate response to reinfusion indicates an increased lactate absorption and thus improved perfusion of poorly perfused tissue in the dextran group. A further, important difference may be due to the different effects on the microcirculation. As evidenced by a decline in the end-expiratory arterial CO2 gradient, dextran effected a significant (P < 0.01) improvement in decreased pulmonary CO2 emission during shock. This indicates a greater rise of blood flow in poorly perfused, ventilated pulmonary areas. In summary, in our model dextran appeared to be the superior colloid compared to HES, particularly during the first hour after initiation of treatment, although direct proof of an improved long term outcome has not been demonstrated.

Acidosis↗
PubMed1987

Comparison of technetium-99m sulfur colloid and technetium-99m albumin colloid labeled solid meals for gastric emptying studies.

A Tc-99m albumin colloid (Tc-AC) kit has been introduced as an alternative to Tc-99m sulfur colloid (Tc-SC) for liver-spleen imaging. Since there is no need for boiling, the use of Tc-AC reduces preparation time and manipulation. Tc-SC is one of the most commonly used radiopharmaceuticals for the labeling of solid-phase markers in gastric emptying studies. In vitro studies were performed to evaluate the labeling efficiency and stability in hydrochloric acid and in human gastric juice of intracellularly labeled chicken liver and scrambled eggs labeled with Tc-SC and Tc-AC. Gastric emptying studies also were performed on 20 healthy volunteers with both Tc-SC and Tc-AC labeled scrambled egg sandwiches. There was no significant difference between Tc-SC and Tc-AC in the labeling efficiency of chicken liver (98% +/- 1% for Tc-SC, 96% +/- 2% for Tc-AC) and scrambled eggs (92% +/- 2% for Tc-SC, 91% +/- 3% for Tc-AC). However, both Tc-SC and Tc-AC labeled scrambled eggs showed a lower stability than chicken liver, particularly in human gastric juice. Gastric emptying curves from both meals in 20 normal subjects were also similar, with a mean half-emptying time of 85 +/- 13 minutes and 87 +/- 16 minutes for the meals containing Tc-SC and Tc-AC respectively. Tc-AC is a reliable alternative to Tc-SC as a radiotracer for solid-phase gastric emptying studies.

Adult↗
PubMed1975

Renal transplantation in the rat. III. The effect of colloidal and non-colloidal perfusates on the clearing of blood from the in vitro perfused rat kidney.

Rat kidneys were perfused in vitro with Perfadex (Gelin's solution) and a modified Collins' C3-solution with or without colloids. When the same flow rate was used the presence of 5% dextran 40, 5% albumin, or 10% albumin did not alter the clearing of 51Cr-tagged red blood cells. The main difference between the experimental groups was a significant increase in perfusion pressure when colloids were excluded from the perfusate. Results concerning the regional distribution of 51Cr-activity within the kidney are discussed.

Albumins↗
PubMed1998

Interactions in Colloidal Mixtures: Partial Structure Factors in Mixtures of Colloidal Silica and an Anionic Oil-in-Water Microemulsion.

We have investigated the colloidal stability and interactions in a mixture of colloidal silica (LudoxTM) and an oil-in-water microemulsion (AOT/decane/brine). Stable silica-microemulsion mixtures containing large fractions of dispersed phase (phioil + phiLudox > 0.36) can be prepared. For fixed silica and AOT concentrations, the addition of decane increases the size of the microemulsion droplets. Since the surfactant concentration remains constant, this droplet growth is balanced by a decrease in the number density of droplets. Partial structure factors for the mixture are extracted from sets of small-angle neutron scattering (SANS) data using a solvent contrast variation technique. The extracted partial structure factors are compared qualitatively to model calculations for a multicomponent sticky hard sphere (SHS) fluid. A shallow contact potential (approximately 2.6 kT) between the Ludox particles is necessary to obtain agreement between model and experiment in the low-q region of the partial structure factors. The magnitude of this contact potential does not change with decane concentration, in agreement with the macroscopic observation that there is no observable change in the stability of these silica-microemulsion mixtures. Copyright 1998 Academic Press.

Journal Article↗
PubMed2004

Electroacoustic theory for concentrated colloids with overlapped DLs at arbitrary kappa alpha. I. Application to nanocolloids and nonaqueous colloids.

Existing theories of electroacoustic phenomena in concentrated colloids neglect the possibility of double layer overlap and are valid mostly for the "thin double layer," when the double layer thickness is much less than the particle size. In this paper we present a new electroacoustic theory which removes this restriction. This would make this new theory applicable to characterizing a variety of aqueous nanocolloids and of nonaqueous dispersions. There are two versions of the theory leading to the analytical solutions. The first version corresponds to strongly overlapped diffuse layers (so-called quasi-homogeneous model). It yields a simple analytical formula for colloid vibration current (CVI), which is valid for arbitrary ultrasound frequency, but for restricted kappa alpha range. This version of the theory, as well the Smoluchowski theory for microelectrophoresis, is independent of particle shape and polydispersity. This makes it very attractive for practical use, with the hope that it might be as useful as classical Smoluchowski theory. In order to determine the kappa alpha range of the quasi-homogeneous model validity we develop the second version that limits ultrasound frequency, but applies no restriction on kappa alpha. The ultrasound frequency should substantially exceed the Maxwell-Wagner relaxation frequency. This limitation makes active conductivity related current negligible compared to the passive dielectric displacement current. It is possible to derive an expression for CVI in the concentrated dispersion as formulae inhering definite integrals with integrands depending on equilibrium potential distribution. This second version allowed us to estimate the ranges of the applicability of the first, quasi-homogeneous version. It turns out that the quasi-homogeneous model works for kappa alpha values up to almost 1. For instance, at volume fraction 30%, the highest kappa alpha limit of the quasi-homogeneous model is 0.65. Therefore, this version of the electroacoustic theory is valid for almost all nonaqueous dispersions and a wide variety of nanocolloids, especially with sizes under 100 nm.

Journal Article↗
PubMed2004

Oppositely charged colloidal binary mixtures: a colloidal analog of the restricted primitive model.

The equilibrium phase diagram of a colloidal system composed of 1:1 mixture of positive and negative particles with equal charge is studied by means of Monte Carlo simulations. The system is the colloidal analog of the restricted primitive model (RPM) for ionic fluids. A liquid-gas transition is found in the low-temperature-low-density region, similar to the liquid-gas transition in the RPM. The fluid-crystal transition is also studied, and the liquid phase is shown to be stable in a narrow range of temperatures. In the liquid, the pair distribution function shows alternating layers of particles with opposite sign of charge surrounding every particle. In the vapor phase, clusters of particles are observed, again in agreement with the RPM. However, a decreasing distribution of clusters is obtained, instead of the discrimination between charged and neutral clusters found in the RPM.

Journal Article↗
PubMed2003

Pathogenesis of colloid (pure mucinous) carcinoma of exocrine organs: Coupling of gel-forming mucin (MUC2) production with altered cell polarity and abnormal cell-stroma interaction may be the key factor in the morphogenesis and indolent behavior of colloid carcinoma in the breast and pancreas.

In the exocrine organs, breast and pancreas, colloid carcinoma (CC, pure mucinous carcinoma), characterized by well-circumscribed lakes of mucin that contain scanty, detached malignant cells, has a significantly better prognosis than conventional ductal carcinomas (DCs). It has been speculated by us and others that an inverse polarization of cells may be responsible for the accumulation of extracellular mucin. Another possibility is that this mucin is biochemically and biologically distinct from the mucin secreted by the conventional carcinomas of these organs. This study was undertaken to investigate these two hypotheses: 1) To test whether there is indeed an alteration in cell polarity in CC. Immunohistochemical stains for luminal surface glycoproteins (carcinoembryonic antigen in pancreas and MUC1 in breast) were performed in 18 pancreatic and 30 mammary CCs and compared with the expression pattern in DCs (37 pancreatic and 47 mammary) and normal ducts. The results disclosed that these glycoproteins were expressed predominantly in the stroma-facing surfaces of CC cells, in contrast to the DCs, in which the expression was either on the luminal surface (in well-differentiated areas) or dispersed throughout the cell, intracytoplasmic in the poorly differentiated areas. Ultrastructural examination performed on 10 breast and two pancreatic CCs showed the condensation of mucigen granules (generally underlying an apical-type cell membrane) in the stroma-facing surface in all cases. In contrast, in the DCs (five pancreatic and five mammary), no clustering of mucigen granules was identified in the cytoplasm facing the stroma in any of the cases. Furthermore, no external lamina or basement membrane was detected in any of the CCs, whereas in the DCs, a distinct (in 3 of 10) or discontinuous (4 of 10) external lamina separated the tumor cells from the stroma. 2) To determine the expression frequency of MUC2 in CCs and to compare it with that in DCs and normal tissue, immunohistochemical stains with MUC2 (clone ccp58) were performed. MUC2 expression was detected in 18 of 18 pancreatic and 30 of 30 breast CCs and was exceedingly rare in DCs (1 of 136 pancreatic DC and 3 of 47 mammary, p <0.0001 in both organs). No labeling was detected in normal ducts. In conclusion, it appears that coupling of two factors is important for the distinctive morphologic characteristics and slow growth of CCs: The first one is the alteration in cell orientation as evidenced by the direction of surface glycoproteins and secretory organelles to the stroma-facing surface of the cells and the disruption of cell-stroma interaction as manifested by lack of basal lamina formation. Apparently, this altered polarity allows the CC cells to secrete the mucin toward the stroma. The mucin produced, MUC2 (also called gel-forming mucin), is highly specific for CC and is known to form strong bonds with the stroma, and also was found recently to have tumor suppressor activity. This distinctive mucin, accumulated in the stroma surrounding the CC cells, may act as a containing factor, slackening the spread of the cells.

Adenocarcinoma, Mucinous↗
PubMed1981

[Changes in the colloid-osmotic pressure by a foreign colloid (dextran 70)].

In 55 patients undergoing elective surgery (general or urological) the colloid osmotic pressure (COP) of serum was followed up until the sixth postoperative day. The patients were divided into two groups, one receiving intra- and postoperative administration of dextran 70 and the other as a control group with no dextran. COP was measured at an artificial membrane (M = 10000) by a transducer; at the same time the concentrations of total protein, albumin and globulin were determined in order to calculate the COP by the formula of Keys. The dextran group and control group showed no difference in the measured COP. This variable reached the lowest value (which was not below 20 mm Hg) on the first postoperative day. The control patients showed close agreement of measured and calculated COP, while the calculated COP of dextran patients was significantly lower than the measured COP until the sixth postoperative day; the artificial membrane thus registered the action of dextran for this length of time. After each dextran infusion the serum proteins fell to a lower level than in the control group. Three possible explanations are discussed: an increase in intravascular volume, accelerated passage of macromolecules through the capillary wall, and a decrease in albumin synthesis.

Aged↗
PubMed1999

Colloidal Stability of Polymer Colloids with Variable Surface Charge.

Colloidal stability of two latexes with variable charge surface groups has been studied at a range of pH. Experimental log W vs log[electrolyte] plots were fitted using the DLVO theory, and values for the diffuse potential, psi(d), and the Hamaker constant, A, were obtained. Reasonable tendency was found for the diffuse potential of both latexes, decreasing when the surface charge decreased. However, the Hamaker constant, which was expected to be constant over the range of pH covered, also showed a decreasing behavior with decreasing charge. Several theories for the electric repulsive potential have been used to try to explain this paradoxing trend, although none of them was successful. Finally, two explanations are proposed, one based on coion adsorption and the other on the hairy layer model, although the first one seems to be the most probable on the basis of thermodynamics considerations. Copyright 1999 Academic Press.

Journal Article↗
PubMed1987

The direct measurement of plasma colloid osmotic pressure is superior to colloid osmotic pressure derived from albumin or total protein.

Plasma colloid osmotic pressure (COP) has been calculated from both serum albumin concentration and plasma total protein concentration. These values have been compared to those measured directly using a membrane-transducer oncometer in a group of normal subjects, in a group of critically-ill patients with a variety of primary diagnoses and in a group of hypovolaemic patients before and after plasma volume replacement with 6% hydroxyethyl starch solution. In the normal samples, COP calculated from albumin (COPalb) underestimated the measured COP (COPm) by mean of 2.0 mmHg (p less than 0.002), with correlation coefficient r = 0.39(n/s). Similarly, the COPalb underestimated COPm by a mean of 5.7 mmHg (p less than 0.001) in the critically ill patient group; r = 0.38 (p less than 0.02). Furthermore, in the patients receiving plasma volume replacement serum albumin concentration fell by 13.1% (p less than 0.001) whilst COPm increased by 11.5% (p less than 0.002). In the normal subjects COP calculated from total protein concentration (COPtp) underestimated the COPm by 1.5 mmHg (p less than 0.02) with r = 0.65 (p less than 0.01). Conversely, in the patient samples, mean COPtp overestimated COPm by 3.5 mmHg (p less than 0.001) with r = 0.73 (p less than 0.002). We conclude that COPalb is an inadequate estimate of COPm particularly in patients where its use may have important clinical consequences. COPtp provides a reasonable estimate of COPm in normal subjects but in patients samples, where albumin: globulin ratio is low COPtp overestimates substantially in many cases. We advocate the direct measurement of COP in critically-ill patients.

Adult↗