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PubMed2004

Phase diagram of aggregation of oppositely charged colloids in salty water.

Aggregation of two oppositely charged colloids in salty water is studied. We focus on the role of Coulomb interaction in strongly asymmetric systems in which the charge and size of one colloid is much larger than the other one. In the solution, each large colloid (macroion) attracts a certain number of oppositely charged small colloids (Z-ion) to form a complex. If the concentration ratio of the two colloids is such that complexes are not strongly charged, they condense in a macroscopic aggregate. As a result, the phase diagram in a plane of concentrations of two colloids consists of an aggregation domain sandwiched between two domains of stable solutions of complexes. The aggregation domain has a central part of total aggregation and two wings corresponding to partial aggregation. A quantitative theory of the phase diagram in the presence of monovalent salt is developed. It is shown that as the Debye-Hückel screening radius r(s) decreases, the aggregation domain grows, but the relative size of the partial aggregation domains becomes much smaller. As an important application of the theory, we consider solutions of long double-helix DNA with strongly charged positive spheres (artificial chromatin). We also consider implications of our theory for in vitro experiments with the natural chromatin. Finally, the effect of different shapes of macroions on the phase diagram is discussed.

Binding Sites↗
PubMed1989

Juvenile colloid milium. Immunohistochemical and ultrastructural studies.

A 7-year-old Italian girl with juvenile colloid milium was studied with histological, immunohistochemical, and electron microscopic methods. This patient had a well-documented history of severe sunburn and developed the lesions on the face shortly afterward. Numerous apoptotic keratinocytes were observed in the lower epidermis. These cells began their degeneration with filamentous whorl formation (or filamentous degeneration) of tonofilaments. In the papillary dermis the colloid substance was resolved by the electron microscopy into either wavy, thin filaments derived from the epidermal keratinocytes or typical amyloid filaments. Many desmosomes and gap junctions were found in the colloid substance. Polyclonal antikeratin antibody (DAKO) was positive in the colloid substance, particularly in the parts close to the epidermis. These findings suggested that juvenile colloid milium is different from adult colloid milium despite clinical similarities and that the former belongs to the group of actinic amyloid K, i.e. amyloidoses due to actinic degeneration of keratinocyte and its keratin.

Child↗
PubMed2006

Diffusing colloidal probes of protein and synthetic macromolecule interactions.

A new approach is described for measuring kT and nanometer scale protein-protein and protein-synthetic macromolecule interactions. The utility of this method is demonstrated by measuring interactions of bovine serum albumin (BSA) and copolymers with exposed polyethyleneoxide (PEO) moieties adsorbed to hydrophobically modified colloids and surfaces. Total internal reflection and video microscopy are used to track three-dimensional trajectories of many single diffusing colloids that are analyzed to yield interaction potentials, mean-square displacements, and colloid-surface association lifetimes. A criterion is developed to identify colloids as being levitated, associated, or deposited based on energetic, spatial, statistical, and temporal information. Whereas levitation and deposition occur for strongly repulsive or attractive potentials, association is exponentially sensitive to weak interactions influenced by adsorbed layer architectures and surface heterogeneity. Systematic experiments reveal how BSA orientation and PEO molecular weight produce adsorbed layers that either conceal or expose substrate heterogeneities to generate a continuum of colloid-surface association lifetimes. These measurements provide simultaneous access to a broad range of information that consistently indicates purely repulsive BSA and PEO interactions and a role for surface heterogeneity in colloid-surface association. The demonstrated capability to measure nonspecific protein interactions provides a basis for future measurements of specific protein interactions.

Colloids↗
PubMed1995

Strongly anionic sites in peripheral axons of the rat sciatic nerve: light and electron microscopic detection using cationic colloidal iron.

Anionic sites in the rat sciatic nerve were studied by light and electron microscopy using a fine-granular cationic colloidal iron staining method (Murakami et al., 1986). The axon, as well as the endoneurium, the epineurium and the basement membrane of Schwann cells, were all confirmed to react strongly to the cationic colloidal iron even at a pH value of 1.0-2.0. Prior hyaluronidase digestion decreased the colloidal strain of the epineurium; chondroitinase ABC weakened that of the endoneurium and the basement membrane of Schwann cells. However, as axons retained stainability with cationic colloidal iron even after combined digestion with hyaluronidase, chondroitinase ABC, heparitinase and keratanase, the authors consider sulfated glycoconjugates and not those substances which are digestible with such common enzymes. The acid groups ionized at pH 1.0 are most likely sulfate groups. Methylation deprived the axon of the reactivity to cationic colloidal iron staining, and even subsequent saponification could not recover this reactivity to its full extent. In the axon, electron microscopy revealed a deposition of colloidal iron on the external surfaces of microtubules and neurofilaments in the axoplasm and of very fine filaments connecting them. This highly negatively charged intra-axonal network could also serve toward a supportive function in maintaining the spatial distribution of microtubules either mechanically or through electrostatic repulsion or, possibly, serve as an intra-axona cation exchange reservoir.

Animals↗
PubMed2003

Colloids versus crystalloids as priming solutions for cardiopulmonary bypass: a meta-analysis of prospective, randomised clinical trials.

Using Cochrane methodology a review was performed of prospective randomized clinical trials comparing colloidal pump priming solutions for cardiopulmonary bypass. Dextrans were not considered. Database searches from 1966 through December 2002 delivered 265 articles. Seventeen studies finally met the eligibility criteria involving 997 patients. Summary odds ratio estimates from the 5 studies reporting mortality were 1.46 (n = 326; 95%-Confidence-Interval: .55 to 3.85; p = .49) for crystalloids against colloids and .74 (n = 150; 95%-Confidence-Interval: .17 to 3.36; p = .49) for albumin versus synthetic colloids. Most commonly used outcome measures further included postoperative blood loss, platelet-count, fluid-balance and, colloid osmotic pressures from which Standardized Mean Differences (SMD) and their 95%-Confidence-Interval (95%CI) were extracted. Colloids produced significantly higher oncotic pressures and less positive fluid-balances. Although across 9 studies postoperative bleeding between colloids and crystalloids did not differ (n = 663; SMD: -.03, 95%CI: -.18 to .12; p = .69), platelet counts significantly favoured crystalloids (n = 465; SMD: -.42; 95%CI: -.68 to -.16; p = .00). However, compared to albumin platelet counts were significantly disfavoured only by starches (n = 321; SMD: -.55; 95%CI: -.77 to -.32; p = .00). To conclude, using mere crystalloids produced more pronounced positive fluid balances and their avoidance as a single pump-prime component can be suggested. Since albumin is not necessarily associated with better outcomes and is more expensive, it is hard to continue its use. However, there is still insufficient evidence available to allow definitive conclusions.

Cardiopulmonary Bypass↗
PubMedDate not supplied

[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↗
PubMed2005

[Effects of oxalate on acid phosphatase adsorption and its activity on soil colloids and minerals].

By a batch method, this paper studied the effects of different concentration and pH of oxalate, an important root exudate, on the adsorption of acid phosphatase and its activity on < 2 microm colloids of yellow brown soil and latosol, and on minerals goethite and kaolinite. The results showed that the acid phosphatase adsorption by goethite was less affected by the concentration of oxalate; while the adsorbed amount of this enzyme by the other test colloids and kaolinite was sharply decreased with the increasing oxalate concentration (0-5 mmol x L(-1)) first, and then gradually increased to the level equal to or less than the blank, which may be related to the coordination type of oxalate on soil colloids and minerals, and their surface charge change and dissolution. In the systems oxalate existed, the adsorbed amount of acid phosphatase by soil colloids and minerals decreased in order of goethite >> yellow brown soil > kaolinite > latosol. The pH value for the maximum adsorption of acid phosphatase was between the IEP of the enzyme and the PZC of test colloids and minerals. After the enzyme was immobilized on colloids and minerals, the pH of its maximum specific activity had no change, or shifted to a higher value.

Acid Phosphatase↗
PubMed1989

[Colloids versus crystalloids in the treatment of hypovolemic or septic shock].

The literature is reviewed with the aim of comparing the effect of resuscitation with colloid solutions with that of crystalloid solutions in the following patient categories: patients undergoing major elective abdominal surgery, patients in hypovolemic shock due to acute trauma and patients in septic shock. None of the clinical trials have documented that resuscitation with colloids is superior to that of crystalloids alone as regards mortality or frequency of complications. On the contrary, colloid resuscitation appears to be detrimental in patients with traumainduced hypovolemic shock with a higher incidence of pulmonary and cardiac complications as compared to resuscitation with crystalloids alone. This is contrary to what is expected from the Starling equation and the discrepancy between the theoretical and clinical findings is discussed. Furthermore, resuscitation with colloids is about 50 times more expensive than resuscitation with crystalloids. On the basis of the clinical data and the higher cost of colloids, the authors recommend cessation of the use of colloids in the abovementioned conditions.

Colloids↗
PubMed1986

Diffusion of thyroglobulin in the follicular colloid. (Minireview).

Methods used for estimating in vivo diffusion velocity of thyroglobulin (Tgb), the factors affecting hydrodynamic properties of thyroidal colloid and the effects of changing diffusion properties on follicular function are briefly reviewed. The principal methods, besides pure in vitro techniques, are autoradiography of thyroid sections after in vivo labelling of Tgb and freezing autoradiography for examining colloidal diffusion of ions or other small molecules. The main factors known to affect diffusion of Tgb in the colloid space are concentration and actual physico-chemical properties of the Tgb molecule itself, the latter parameter depending on several factors such as sugar content, iodination degree, etc. Additional factors are thyrotropin which speeds up and drugs such as pentobarbital or verapamil which slow down the velocity of Tgb diffusion. High iodine supply has a retarding effect on Tgb diffusion in the colloid of mice thyroids. Any change of Tgb diffusion in the colloid may have a striking effect on follicular function. The hydrodynamic properties of the colloid components are increasingly recognized as a potentially important factor in regulating kinetics of hormone synthesis.

Animals↗
PubMed1987

The "critical colloid dose" in studies of reticuloendothelial function.

The [99mTc]sulfur colloid distribution in rat organs was investigated after the administration of different amounts of colloid particles. Saturation of the liver and spleen was not observed. Blood clearance was significantly reduced 15 min after injection above approximately 3 X 10(9) particles per kg body weight. With an increasing number of injected particles, lung uptake increased and bone marrow uptake decreased. Microfiltration studies showed that the colloid is unaffected by dilution with saline but may be affected after incubation in normal rat plasma. We conclude that the distribution of [99Tc]sulfur colloid in organs varies with the number of injected particles and therefore, is not dependent upon the blood flow to the reticuloendothelial organs alone. The "critical colloid dose" may differ among the reticuloendothelial organs and cannot, therefore, be evaluated by blood clearance measurements alone. The considerable influence of the number of injected colloid particles on bone marrow uptake should also be recognized when carrying out dosimetric calculations.

Animals↗
PubMed1986

Crystalloids versus colloids: implications in fluid therapy of dogs with intestinal obstruction.

Responses of jejunal transcapillary and transmucosal fluid fluxes to IV infusion of crystalloid or colloid solutions were evaluated in 12 dogs. One isolated intestinal segment in each dog was used as the control segment, and 2 segments were distended to a intraluminal hydrostatic pressure of 10 cm of H2O. The artery supplying 1 of the 2 distended (autoperfused) segments was cannulated and perfused with blood from the femoral artery. One of the 2 distended segments was autoperfused from the femoral artery. Intraluminal pressure was increased in the autoperfused segment and in 1 other segment for three, 20-minute periods after administration of the crystalloid or colloid solution. Net transmucosal fluid flux was estimated, using a volume recovery method. In each autoperfused segment, blood flow, capillary pressure, lymph flow, and plasma protein and lymph protein concentrations were measured during each 20-minute distention period. Systemic arterial pressure was monitored throughout the procedure. Plasma and tissue oncotic pressures were calculated from the plasma protein and lymph protein concentrations. Total vascular resistance and precapillary and postcapillary resistances were determined. Capillary pressure increased after infusion with colloids and crystalloids, with the effects being more prolonged in the colloid group. Plasma oncotic pressure transiently increased after infusion with colloids and decreased after infusion with crystalloids. Lymph flow increased only in crystalloid-treated dogs. Due to alterations in transcapillary fluid filtration, crystalloids induced a net loss of fluid into the intestinal lumen, whereas the fluid absorptive capacity of the jejunum was unaltered by colloid treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

Colloid and crystalloid fluid resuscitation.

The choice of colloid or crystalloid solutions for fluid resuscitation of critically ill patients remains controversial. Marked reduction of extracellular water is considered an important defect in shock by proponents of crystalloid fluid therapy. Large volumes of crystalloid replenish this extracellular deficit. Hypovolemia is regarded as the primary defect in shock by those favoring colloid fluid therapy. Colloidal fluids promptly restore plasma volume and reestablish hemodynamic stability with substantially lesser volumes of fluid. However, only 8% of infused water and less than 25% of infused saline are retained in the intravascular fluid compartment after 1 h. On the other hand, almost the entire volume of iso-oncotic colloid is retained with the intravascular space after 1 h. Hypertonic saline decreases intracellular fluid volume. Hyperoncotic colloid decreases both interstitial and intracellular fluid volumes as it disproportionately expands intravascular volume. The choice of fluid is not only contingent on the restoration of intravascular volume, the rapidity with which it is accomplished and the duration of its effect, but also on the adverse effects that follow fluid resuscitation. This is of greatest moment in the fluid resuscitation of patients in whom circulatory shock follows volume depletion. Crystalloid fluid repletion which requires between 2- and 4-fold as much volume as colloidal fluid is of little risk in the young, traumatically injured patient. However, in older patients, the risk of pulmonary edema is increased.

Albumins↗
PubMed1982

[Gastrointestinal transit in the chicken using 198Au-colloid as a marker (author's transl)].

Gastrointestinal transit in the chicken was investigated by using 198Au-colloid as a marker. Gastrointestinal transit was determined following administration of a 198Au-colloid solution (370 kBq (10 microCi), 0.5 ml) into the proventriculus by measuring the distribution of radioactivity in the gastrointestine. Most of 198Au-colloid administered into the proventriculus was transferred instantly to the gizzard and subsequently, some part of it quickly to the duodenum and the upper segment of the jejunoileum. A considerable quantity of 198Au-colloid in the duodenum, the upper and middle segment of the jejunoileum regurgitated to the gizzard. 198Au-colloid transferred to the caecum was retained for a long time (more than 48 hours) in these segments. A part of 198Au-colloid was found in the feces 90 to 120 minutes after administration into the proventriculus and the greater part of it was excreted into the feces 24 to 48 hours. Subcutaneous administration of acetylcholine (2 mg/kg) increased the gastrointestinal transit but atropine (2 mg/kg) decreased.

Acetylcholine↗
PubMed1984

Increased pulmonary edema with crystalloid compared to colloid resuscitation of shock associated with increased vascular permeability.

Physiologic effects of colloidal (5% albumin, 6% hydroxyethylstarch, 6% dextran-70) and crystalloidal (Ringer's lactate) fluids were examined in rats (six in each fluid group) after infusion of an LD99 of rattlesnake venom, previously shown to produce shock secondary to increased vascular permeability. Venom infusion (iv, 2.0 mg/kg, 30 min) was followed by fluid infusion (iv, 30 min) in quantities sufficient to reverse venom-induced hemoconcentration. Venom infusion decreased mean arterial pressure, increased blood lactate, and increased hematocrit in all animals (p less than .01). Fluid infusion reversed these changes, although six times the volume of crystalloid was required to produce hemodilution comparable to the colloidal fluids (120 ml/kg Ringer's lactate, 20 ml/kg colloids). Although no significant changes in the respiratory parameters were noted after administration of the three colloids, Ringer's lactate produced decreases in PaC2 (107 +/- 6 torr, mean +/- SEM to 72 +/- 7, p less than .05), increases in PaCO2 (30 +/- 4 torr to 55 +/- 5, P less than .001), decreases in plasma colloid osmotic pressure (14.2 +/- 0.8 torr to 6.6 +/- 0.9, p less than .001) at the end of fluid infusion. These changes were associated with significantly increased wet-dry lung ratios (p less than .001) in identically prepared animals, sacrificed after fluid infusion. In spite of the development of pulmonary edema in the crystalloid-treated animals, survival was similar for each group (6/6 for albumin and dextran, 5/6 for hydroxyethylstarch and Ringer's lactate). We thus conclude that both colloidal and crystalloidal fluid resuscitation leads to survival in permeability shock. Resuscitation with crystalloidal fluid, however, requires significantly greater volumes and is associated with the development of pulmonary edema.

Animals↗
PubMed1982

Measurements of serum colloid osmotic pressure are of limited usefulness.

We examined the usefulness of serum colloid osmotic pressure measurement in patients with chronic rather than acutely occurring low serum protein concentrations. We used two oncometers, the IL 186 Weil Oncometer and the Wescor Model 4100; results from the two instruments were interchangeable. Values for the colloid osmotic pressure were compared with those for serum total protein (r = 0.783) and albumin concentrations (r = 0.882), which were similar to previously published values. Our day-to-day CV was 2.8%. In studying over 100 patients we found that the previously reported occurrence of pulmonary edema in almost all patients whose colloid osmotic pressure was less than 12.5 mmHg was not seen in the chronic hypoproteinemic patients. We noted only one fatality in our patients whose colloid osmotic pressure was less than 10.5 mmHg, a value found to be associated with fatality in one previous study of acutely ill patients. Factors such as ambulation, fasting, dehydration, and the nature of the blood sample can markedly affect the value for colloid osmotic pressure value, and this, coupled with the good correlation with the serum albumin in several studies, leads us to question the usefulness of measuring colloid osmotic pressure in a non-specialist hospital environment, either as an adjunct to the measurement of serum protein or albumin, or as an independent test.

Adult↗
PubMed1994

Storage of pancreatic digest before islet purification. The influence of colloids and the sodium to potassium ratio in University of Wisconsin-based preservation solutions.

The density-dependent purification of islets from several species of mammalian pancreata is improved by prior storage of the dispersed, collagenase-digested pancreas in suitable storage solutions, such as University of Wisconsin (UW) solution. The optimal composition of such solutions, however, is not fully established, although previous investigations have suggested separately that cellular impermeants and colloids are important components. To investigate this issue further, dispersed tissues from 7 porcine and 7 human pancreata were stored in UW or in solutions containing the impermeants lactobionate and raffinose, with either no added colloid or in the presence of the colloids hydroxyethyl starch, dextran 40, dextran 250, or Ficoll 400; hydroxyethyl starch-containing solutions in which the principal cation was sodium, rather than potassium, were also studied. Subsequent purification of islets on continuous linear density gradients of BSA was then assessed by insulin/amylase assay of gradient fractions. Islet purity was slightly reduced using solutions containing impermeants but lacking a colloid, compared with using UW. In the combined presence of impermeants and a colloid, however, islet purity was similar to that obtained with UW, and for porcine pancreata, solutions containing Ficoll 400 or dextran 40 were slightly superior to UW. Purity was not, however, influenced by the sodium to potassium ratio of storage media. In conclusion, impermeants and colloids are both essential components of solutions used to preserve pancreatic tissue before islet purification, findings which may be relevant when designing media for use during other phases of islet isolation, e.g., during collagenase digestion/density gradient purification.

Adenosine↗
PubMed1995

[Effect of colloidal plasma substitutes on liberation of tumor necrosis factor-alpha (TNF-alpha) in human whole blood in vitro].

OBJECTIVE: To investigate the influence of colloidal plasma substitutes on human cytokine network, especially of tumor necrosis factor alpha (TNF-alpha), in vitro. DESIGN: Heparinized whole blood samples from 8 healthy volunteers were divided and set on various concentrations of artificial colloidal plasma substitutes (native = 0 mg/ml; 5 mg/ml; 15 mg/ml). As colloids were used hydroxyethyl starch 200/0.5 (HES), dextran 60 (DX), urea-linked gelatin (GEL) and human albumin solution (HA). After incubation (24 h; 5% CO2; 37 degrees C; with and without concomitant stimulation of blood cells with phytohemagglutinin [PHA]) measurement of TNF-alpha release was performed via ELISA by the method described by Gallati. For the statistical evaluation a repeated measures analysis of variance was used. RESULTS: Basic level of TNF-alpha was found between 226 and 273 pg/ml (0 mg of each colloid/ml), stimulation with PHA without any colloid increased the TNF-alpha level about fourfold (1,066-1,260 pg/ml; 0 mg of each colloid/ml). At 5 mg/ml and 15 mg/ml without PHA all 3 artificial colloids rose the level of TNF-alpha (up to 50%). Under concomitant stimulation each colloid induced additional TNF-alpha release in comparison to PHA alone. The changes elicited by DX and GEL were statistically significant (p < 0.001 and p = 0.005, respectively) in contrast to those induced by human albumin solution or HES. CONCLUSION: In relation to TNF-alpha plasma substitutes are not inert substances as perhaps suspected. The questions whether the observed effects exist in vivo how far other cytokines are influenced and the question about the clinical importance are subject of ongoing studies.

Colloids↗
PubMed1998

Improved sentinel lymph node localization in patients with primary melanoma with the use of radiolabeled colloid.

BACKGROUND: The purpose of this study was to determine whether the sentinel lymph node (SLN) localization technique, which uses blue dye and 99mTc-labeled sulfur colloid, provides advantages over blue dye alone in the management of patients with stages I and II cutaneous melanoma. METHODS: The records of 626 consecutive patients with melanoma who underwent lymphatic mapping and SLN biopsy between 1991 and 1997 at the M.D. Anderson Cancer Center were reviewed. Lymphatic mapping was performed with isosulfan blue dye alone (n = 252) or in combination with 99mTc-labeled sulfur colloid accompanied by a hand-held gamma probe (n = 374). SLNs were defined as those that stained blue or demonstrated increased focal radiotracer uptake. RESULTS: SLN identification rates improved from 87% (dye alone) to 99% (dye and colloid) (P < .0001) with the combined technique in all anatomic sites examined. The mean number of SLNs harvested from each basin was significantly greater in the patients mapped with dye and colloid (1.74 vs 1.31; P < .0001). Occult metastatic disease was identified in 17.5% of all patients and did not significantly differ between groups. In 92% of patients who had at least one positive SLN and were mapped with both agents, lymphatic metastases were identified in the SLN that contained the greatest radiotracer uptake. CONCLUSIONS: SLN identification is enhanced by the addition of radiolabeled sulfur colloid and intraoperative use of the hand-held gamma probe and may identify SLNs missed by the blue dye alone. These data support the combined use of radiolabeled sulfur colloid and blue dye in lymphatic mapping procedures to improve the nodal staging of stages I and II melanoma.

Adolescent↗