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PubMed2004

Rotational dynamics of colloidal spheres probed with fluorescence recovery after photobleaching.

We report a polarized fluorescence recovery after photobleaching (pFRAP) method to measure the rotational dynamics of fluorescent colloids over a wide dynamic range. The method is based on the polarization anisotropy in the fluorescence intensity, generated by bleaching of fluorescently labeled particles with an intense pulse of linearly polarized laser light. The rotational mobilities of the fluorescent particles can be extracted from the relaxation kinetics of the postbleach fluorescence polarization anisotropy. Our pFRAP setup has access to correlation times over a range of time scales from tens of microseconds to tens of seconds, and is highly sensitive, so very low concentrations of labeled particles can be probed. We present a detailed description of the theoretical background of pFRAP. The performance of the equipment is demonstrated for fluorescent colloidal silica spheres, dispersed in pure solvents as well as in fd-virus suspensions.

Biomechanical Phenomena↗
PubMed2004

Small-angle neutron scattering study of structural changes in temperature sensitive microgel colloids.

The structure of temperature-sensitive poly(N-isopropylacrylamide) microgels in dilute suspension was investigated by means of small-angle neutron scattering. A direct modeling expression for the scattering intensity distribution was derived which describes very well the experimental data at all temperatures over an extensive q range. The overall particle form as well as the internal structure of the microgel network is described by the model. The influence of temperature, cross-linking density, and particle size on the structure was revealed by radial density profiles and clearly showed that the segment density in the swollen state is not homogeneous, but gradually decays at the surface. The density profile reveals a box profile only when the particles are collapsed at elevated temperatures. An increase of the cross-linking density resulted in both an increase of the polymer volume fraction in the inner region of the particle and a reduction of the smearing of the surface. The polymer volume fraction inside the colloid decreased with increasing particle size. The structural changes are in good agreement with the kinetics of the emulsion copolymerization used to prepare the microgel colloids.

Acrylic Resins↗
PubMed2002

Agitated colloid is superior to saline and equivalent to levovist in enhancing tricuspid regurgitation Doppler envelope and in the opacification of right heart chambers: a quantitative, qualitative, and cost-effectiveness study.

BACKGROUND: Doppler spectrum of tricuspid regurgitation (TR) is used to noninvasively assess right ventricular (RV) pressure. With mild TR, the native (Nat) TR envelope may not allow accurate pressure evaluation. Proprietary contrast agents, such as Levovist (Lev) can be used to augment TR Doppler and opacify right-sided heart chambers, but they are expensive, and their efficacy has not been objectively evaluated in patients with difficult baseline studies or compared with less expensive saline (Sal) or colloid solutions, such as Gelofusine (Gel). METHODS: Twenty-five consecutive patients with poor quality Nat TR envelopes on transthoracic echocardiogram were reexamined after serial intravenous injection of 3 contrast agents (Sal, Gel, and Lev). Doppler signals for each agent recorded on video and digitally on optical disk were assessed for signal quality, estimated RV pressure, interobserver and intraobserver variation, and longevity of signal. Quality of right ventricular-right atrial (RV-RA) opacification was also determined for Sal and Gel. Of the 25 patients, 9 underwent percutaneous right-sided heart catheterization. We used the pressures obtained from the catheterization to independently evaluate the pressure estimates from echocardiography. RESULTS: All 3 contrast agents significantly improved the mean quality grade (grades 0-5) of TR envelopes (Nat 1.12, Sal 1.97, Gel 2.56, Lev 2.41, P <.001), decreased the number of uninterpretable envelopes (grade 0) (Nat 49%, Sal 12%, Gel 4%, Lev 12%, P <.0001 for comparison of each agent relative to Nat), and improved the correlation between echocardiographic and catheter-derived RV-RA pressure measurements (Nat r = 0.65, Sal r = 0.75, Gel r = 0.90, Lev r = 0.88). The persistence of enhanced Doppler signals of interpretable quality (> grade 1) was greater for Lev (15.8 seconds) and Gel (15 seconds) than Sal (7.6 seconds) (P =.002). Opacification of RV and RA, measured as mean luminosity score during 2-dimensional harmonic imaging, was significantly higher for Gel than Sal (92.84 +/- 31.2 vs 56.06 +/- 25.6, respectively; P =.0003). Sal, Gel and Lev, respectively, cost $0.10, $2.50, and $75.00 per study. CONCLUSION: Agitated colloid is a novel, effective, and inexpensive alternative to proprietary agents and saline for the assessment of pulmonary systolic pressure and right-sided heart opacification.

Atrial Function, Right↗
PubMed2001

A comparison of heat-induced hyperactivation in patients' sperm after colloid or pentoxifylline wash methods.

OBJECTIVE: Our purpose was to compare kinematic parameters of human sperm after processing through two different wash methods and 40 degrees C heat treatment. STUDY DESIGN: Sperm specimens (N = 169 cases) were washed by either colloid or pentoxifylline wash methods, and the motility parameters were measured at either 37 degrees C or 40 degrees C at baseline (0 hours) and after 4 hours. Five randomly selected washed specimens with matching 37 degrees C (control) or 40 degrees C heat treatments were assessed for changes in a sentinel gene. RESULTS: The percentage of sperm hyperactive motility was >5 times higher after the 40 degrees C heat treatment, in comparison with the 37 degrees C treatment, for both the colloid- and the pentoxifylline-washed sperm. The percentages of total motility and progression were equally enhanced in heated sperm for the two wash methods. No changes were detected in the sentinel gene with the heat treatment. CONCLUSION: Sperm cells mildly heated at 40 degrees C responded with greater motility, progression, and hyperactivation. The data suggest that mild heat is a stimulus for sperm function because greater sperm hyperactivation is associated with increased sperm fertilizing capacity. The absence of change in the sentinel gene in heated sperm suggests that a temperature of 40 degrees C is too low to initiate alterations in the highly condensed sperm chromatin. More studies are needed before mild heating of ejaculated sperm becomes acceptable for use in assisted reproductive technologies.

Colloids↗
PubMed2002

Colloidal assemblies on patterned silane layers.

The site-selective assembly of colloidal polymer particles onto laterally patterned silane layers was studied as a model system for the object assembly process at mesoscale dimensions. The structured silane monolayers on silicon oxide substrates were fabricated by a combination of liquid- and gas-phase deposition of different trialkoxysilanes with a photolithographic patterning technique. By using this method various types of surface functionalizations such as regions with amino functions next to areas of the bare silica surface or positively charged regions of a quaternary ammonium silane surrounded by a hydrophobic octadecylsilane film could be obtained. Furthermore, a triethoxysilane with a photoprotected amino group was synthesized, which allowed direct photopatterning after monolayer preparation, leading to free NH(2) groups at the irradiated regions. The different silane monolayer patterns were used to study the surface assembly behavior of carboxylated methacrylate particles by optical and scanning electron microscopy. In dependence of the assembly conditions (different surface functionalizations, pH, and drying conditions), a selective preference of the particles for a specific surface type versus others was found. Site-specific colloid adsorption could be observed also on the photosensitive silane layers after local deprotection with light. From the photosensitive silane and positively charged ammonium silane, molecularly mixed monolayers were prepared, which allowed particle adsorption and photoactivation within the same monolayer as shown by fluorescence labeling.

Carboxylic Acids↗
PubMed1981

Colloidal gold--low density lipoprotein conjugates as membrane receptor probes.

We have developed a method for conjugating low density lipoproteins (LDL) with colloidal gold. Conjugation, complete after 1 min, occurs by electrostatic adsorption of the LDL to the negatively charged gold particle. Each conjugate consists of approximately eight biologically active LDL molecules clustered around a central 19-nm gold granule. Acidic (pH 4), alkaline (pH 9), or high ionic (600 milliosmolar NaCl) environments do not dissociate the conjugate. Colloidal gold is an electron-dense, nondegradable marker that is easily identified within the cell and serves as a valuable probe for studying receptor binding and endocytosis. By using a modified method of ruthenium red staining, the LDL molecules of the conjugate can be directly visualized when they are bound to the cell surface receptor. Receptor binding (4 degrees C) of the conjugate by cultured human fibroblasts reveals that the gold granule is positioned 18-21 nm from the coated pit region of the membrane. This distance, similar to the diameter of LDL, suggests concomitant internalization of the receptor during vesicular endocytosis and early lysosomal incorporation (10 min at 37 degrees C). Continued internalization (30-60 min at 37 degrees C) results in the formation of free pools of gold within the lysosome.

Cell Membrane↗
PubMed1985

Colloid osmotic pressures, plasma volume and interstitial fluid volume in patients with heart failure.

In 13 patients with heart failure colloid osmotic pressure in plasma (IIp) and in subcutaneous interstitial fluid from thorax (IIi) (wick technique), plasma volume (PV) and interstitial fluid volume (IFV) were measured and correlated to haemodynamic parameters (cardiac index (CI) and right atrial pressure (RAP]. In seven patients with anasarca measurements of IIp, IIi, PV and IFV were repeated after fluid withdrawal (mean 7786 ml) by ultrafiltration. In the patients, IIi was reduced compared with normal subjects (11.5 +/- 3.4 versus 15.8 +/- 2.7 mmHg, p less than 0.01 (mean +/- SD] and transcapillary colloid osmotic gradient (IIp - IIi) increased (14.6 +/- 2.3 versus 12.8 +/- 2.7 mmHg, p less than 0.05). The IFV in the patients was increased to 137% of values in normal subjects (p less than 0.01) and the ratio PV/IFV significantly reduced. Correlations were found between IIi and CI (r = 0.69, p less than 0.01) and IIi and RAP (r = 0.78, p less than 0.01). Ultrafiltration led to a parallel decrease in PV and IFV and increase in IIp. The results indicate that reduced IIi is an important factor limiting peripheral oedema in heart failure and the reduction is more pronounced in severe heart failure. The reduction of IIi is due to both dilution of interstitial proteins and to reduction of interstitial protein mass by lymphatic wash-out.

Adult↗
PubMed2005

Acute pulmonary toxicity caused by exposure to colloidal silica: particle size dependent pathological changes in mice.

To compare the pulmonary toxicity between ultrafine colloidal silica particles (UFCSs) and fine colloidal silica particles (FCSs), mice were intratracheally instilled with 3 mg of 14 nm UFCSs and 230 nm FCSs and pathologically examined from 30 minutes to 24 hour postexposure. Histopathologically, lungs exposed to both sizes of particles showed bronchiolar degeneration and necrosis, neutrophilic inflammation in alveoli with alveolar type II cell swelling and particle-laden alveolar macrophage accumulation. UFCSs, however, induced extensive alveolar hemorrhage compared to FCSs from 30 minutes onwards. UFCSs also caused more severe bronchiolar epithelial cell necrosis and neutrophil influx in alveoli than FCSs at 12 and 24 hours postexposure. Laminin positive immunolabellings in basement membranes of bronchioles and alveoli of UFCSs treated animals was weaker than those of FCSs-treated animals in all observation times. Electron microscopy demonstrated UFCSs and FCSs on bronchiolar and alveolar wall surface as well as in the cytoplasm of alveolar epithelial cells, alveolar macrophages and neutrophils. Type I alveolar epithelial cell erosion with basement membrane damage in UFCSs treated animals was more severe than those in FCSs-treated animals. At 12 and 24 hours postexposure, bronchiolar epithelial cells in UFCSs-treated animals showed more intense vacuolation and necrosis compared to FCSs-treated animals. These findings suggest that UFCSs have greater ability to induce lung inflammation and tissue damages than FCSs.

Animals↗
PubMed1981

Plasma proteins and colloid osmotic pressure of blood of rat fetuses prenatally exposed to Mirex.

A significant effect of prenatal exposure to the pesticide Mirex is a fetal edema, which is responsible for many of the toxic effects of this agent. Pregnant rats were given 6 mg/kg mirex on d 8 1/2-15 1/2, a moderate dose that does not cause maternal mortality. The blood of 18 1/2- and 20 1/2-d rat fetuses was tested to determine a possible cause of the edema. There were no significant differences between fetal and maternal plasma or between control and treated fetal plasma with respect to sodium and potassium concentrations or total osmolality. The protein concentration of plasma of treated fetuses was lower than that of controls. This effect was proportional to the degree of edema. The concentration in 20 1/2-d controls was 25.2 mg/ml, that in mildly swollen treated fetuses 18.1 mg/ml, and that in severely swollen ones 13.5 mg/ml. Polyacrylamide gel electrophoresis showed quantitative and qualitative changes in plasma of affected fetuses. The colloid osmotic pressure was also reduced fron 8.0 mm in controls and unaffected treated fetuses to 4.8 mm in swollen fetuses. Since lowered plasma protein and colloid osmotic pressure cause tissue edema in adults, they are the probably cause of mirex-induced fetal edema.

Animals↗
PubMed2006

Rapid analytical detection of microcystins using gold colloidal immunochromatographic strip.

Routine monitoring of microcystin in natural waters is difficult because the concentration of the toxin is low and the detection method is usually complicated. We developed a rapid analytical detection method of microcystins gold colloidal immunochromatogeraphic strip. The sensitivity of the strip is about 1 ng/mL for microcystin LR; it is able to distinguish visually among different concentrations of microcystin solutions. The developed gold colloidal strip can detect microcystins within 15 min and does not require either a complicated extraction system, or trained or qualified experts.

Antibodies, Monoclonal↗
PubMed2001

A nifedipine coground mixture with sodium deoxycholate. I. Colloidal particle formation and solid-state analysis.

Sodium deoxycholate (DCNa) is a bile salt that forms multimolecular inclusion compounds with a variety of organic substances. In this study, complex formulation of DCNa with nifedipine, a poorly water soluble drug, by grinding was investigated. The coground mixture was prepared with a vibration rod mill, and its solid state was characterized using powder X-ray diffraction, differential scanning calorimetry (DSC), and Fourier transform infrared (FTIR) spectroscopy. A laser diffraction particle size analyzer was also used to determine the particle size distribution curve in solution. When a nifedipine-DCNa (1:2 w/w) mixture coground for 30 min was dispersed into water and a pH 6.8 buffer solution, a semitransparent colloidal solution occurred immediately; 90% of the total particles formed in solution had a diameter less than 600 nm. Both powder X-ray diffraction peaks and DSC endothermic peak of nifedipine crystals were not found for the coground mixture, whereas a new exothermic peak was observed on DSC thermograms. The magnitude of this exothermic peak depended on the weight fraction of DCNa and the grinding time, indicating that nifedipine crystals changed into an amorphous state by complex formation with DCNa during the grinding process. In the FTIR spectrum of the coground mixture, the peaks of aromatic CH out-of-plane bend and dihydropyridine NH stretch of nifedipine were considerably weakened, suggesting that van der Waals interaction may be present between the drug and DCNa molecules. From these results, it is clear that the cogrinding method with DCNa is very useful for the formation of amorphous nifedipine in the solid state and the production of colloidal particles of the drug in solution.

Buffers↗
PubMed1984

A novel approach for scanning electron microscopy of colloidal gold-labeled cell surfaces.

A method is described for the use of scanning electron microscopy on the surface of gold-labeled cells. It includes the use of 45- or 20-nm colloidal gold marker conjugated with Staphylococcal protein A. The marker is best recognized on the basis of its atomic number contrast by using the backscattered electron imaging mode of the scanning electron microscope. When the backscattered electron signal is mixed with the secondary electron signal, an optimum correlation between the distribution of the labeled sites and the cell surface structures is demonstrated. The method is illustrated by its application to the identification of human circulating granulocytes. Its good resolution, high contrast, and good labeling efficiency offers a promising approach to the specific localization of cell surface antigenic sites labeled with particles of colloidal gold.

Erythrocytes↗
PubMed1964

THE ENTRY AND DISTRIBUTION OF HERPES VIRUS AND COLLOIDAL GOLD IN HELA CELLS AFTER CONTACT IN SUSPENSION.

The way in which herpes virus of a well adapted strain penetrates susceptible HeLa cells has been investigated using thin sectioning techniques for electron microscopy. Mature virus particles and cells were mixed together in suspension cultures for 15, 30, 60, or 120 minutes so that the stages in virus uptake could be followed in sequence. The ingestion of particles of colloidal gold by HeLa cells under similar conditions was studied for comparison in parallel experiments. After 15 minutes' contact, the mature virus was found adsorbed on the surface of the cells but separated from them by a narrow gap in which phosphotungstic acid staining was sometimes able to reveal an extraneous coat which appeared as an amorphous layer on the outer aspect of the plasma membrane. When mixing continued for longer the particles were present in deep invaginations or actual cytoplasmic vacuoles, with their outer layers in various stages of stripping and digestion. The stripped, naked, central portion of the virus was occasionally found in these vacuoles but was more commonly free in the cytoplasmic matrix; the mode of transition between these sites could not be determined. Where contact continued for 2 hours these phenomena were much less frequently observed. The larger particles of colloidal gold were ingested in the same way as the virus, but smaller ones were taken up in micropinocytosis vesicles. The gold passed through membrane-bounded cytoplasmic spaces to accumulate in vacuoles from which, in contrast to herpes particles, it did not escape. These findings are discussed, and considered with particular reference to their bearing on the initiation of infection, the uptake and disposal of particles by cells, and the influence on the latter of virus morphology.

Cytoplasm↗
PubMed2005

Effects of radiosynovectomy with p-32 colloid therapy in hemophilia and rheumatoid arthritis.

AIM: The aim of this study was to assess the effects of treatment with our locally produced P-32 colloidal suspension on knee synovitic inflammations of hemophilic and rheumatoid arthritis (RA) patients, as well as to compare results with chemical synovectomy or corticoid intra-articular injections and evaluate the cost-benefit ratio. MATERIALS AND METHODS: Thirty-six hemophilic male patients, 4-28 years of age and sent by the Hemophilic Foundation (Buenos Aires, Argentina), were enrolled for knee radiosynovectomy (RS) with P-32 colloid (26 patients), or the antibiotic rifampicin with the cooperation of orthopaedists (10 patients). Parents' informed consent was obtained. The following procedures were performed: routine blood tests, X-ray, ultrasound, a 3-phase bone scan, plus monthly methylene diphosphonate (MDP) controls. Patients were included in this study only if several knee episodes had occurred. Exclusion criteria included bone destruction and big Baker's cyst. Twelve RA patients were included, with similar selection criteria: 6 RA patients received P-32 therapy, and the other 6 patients intra-articular corticoids. Clinical, blind evaluation (state of joint involvement, pain, motility, requirements of antihemophilic factors, corticoids, or analgesics) was registered in follow-up charts. If required, joint aspiration was carried out. Intra-articular instillation of saline plus flushing was done before the needle was withdrawn. P- 32 Bremsstrahlung emission was used in the gamma camera for early and late imaging to confirm the absence of leakage. For intra-articular chemical injections therapy, 4 MBq of Tc-99m MAA (macroaggregates) was used. Immobilization and relative rest for 72 hours followed the procedures. RESULTS: There were neither local or systemic effects, nor leakage during P-32 treatment. Intra-articular rifampicin and corticoids procedures required frequent injections. Comparison of regions of interest (ROIs) in treated knees during soft-tissue scintigraphies in pre- and post-third MDP control showed knee improvement. The follow-up evaluation demonstrated an increase in joint motion, diminished volume, and less requirement and frequency of the use of antihemophilic factors (AHF) in 80% of the radiosynovectomies (21 of 26), thus lowering health costs. Five female RA patients (5 of 6) had decreased joint swelling and pains, resulting in increased joint motion. CONCLUSIONS: Radiosynovectomy in RA showed a 3-month pain palliative effect. One intra-articular knee radiosynoviorthesis in haemophilic patients provides a more than 3- month relief of symptoms after treatment with locally produced P-32 (11 patients). This turned out to be a safe, economic alternative procedure in emerging nations where the availability of AHF is difficult and expensive.

Adolescent↗
PubMed1997

Colloidal systems for tumor targeting.

The potential and limitations of targeted delivery of anticancer agents with colloidal particulate carriers is the subject of this contribution. Because over the years liposomes have gained the most attention as carrier system in the category of colloidal carrier systems, this paper focuses on the utility of the liposomal system for tumor targeting. It is imperative that an intended therapeutic application of liposomes should be well matched with the liposome behavior in vivo. Therefore, the in vivo fate of the first-generation liposomes and the more recently developed second-generation liposomes (surface-modified liposomes such as the immunoliposomes and long-circulating liposomes) is analyzed in terms of accessibility of target sites, time-, and site-controlled drug release and potential target sites for rational targeted delivery are discussed. A few examples of areas in cancer chemotherapy, with a strong rationale for the use of liposomes, are given. It is concluded that, although several options are available on the drawing board, issues such as tumor cell heterogeneity, access to the target site, shedding of antigens, and target site-specific release of the liposome-associated drug need to be addressed early in the development process.

Animals↗
PubMed2006

Intratissular lymphaticovenous anastomoses demonstrated by perioperative intramuscular injection of 99mTC-colloids.

BACKGROUND: The existence of intratissular lymphaticovenous anastomoses has often been suggested, but it has never been demonstrated. This study aims at demonstrating the presence of such anastomoses. METHODS AND RESULTS: The free flap model was used to investigate the drainage of radiolabeled colloid particles whose size prevents direct passage to the blood vessels. The tracer was injected into the muscle or the skin during the surgical procedure. Blood samples were sequentially drawn from the venous pedicle over the 30 minutes that followed the tracer injection. The blood samples were counted using a gamma well-counter. In all 14 patients, the venous blood radioactivity steadily increased over time. Radiochemical analyses performed on the blood samples demonstrated that the radioactivity is related to the labeled colloids and not to free pertechnetate. Planar imaging performed 24 hours after the surgical procedure showed a significant liver uptake, and no accumulation in the area of normal lymphatic relays. CONCLUSIONS: As, in the free flap model, there is no lymphatic drainage through the classical pathways whatsoever, and since the size of the radiolabeled particles prevents them from directly entering the blood stream, the results strongly suggest the presence of functional intratissular lymphovenous anastomoses.

Butanones↗
PubMed1992

Colloid (3% Dextran 70) with or without ephedrine infusion for cardiovascular stability during extradural caesarean section.

Using a non-invasive cardiac output monitor (Bo-Med NCCOM 3-R7), we have compared cardiovascular responses, degree of haemodilution and incidence of nausea during extradural Caesarean section in healthy non-labouring mothers given either ephedrine 17.5 mg and 3% Dextran 70 7.5 ml kg-1 before delivery (group A) or volume loading with Dextran 15 ml kg-1 without infusion of ephedrine (group B). Smallest systolic arterial pressures before delivery were 114 (SEM 4) mm Hg (group A) and 105 (5) (group B). There were no significant differences between the groups in mean arterial pressure, heart rate, systemic vascular resistance or central venous pressure, while cardiac output increased more with the ephedrine infusion (P less than 0.05). Haemodilution was 8% in group A and 16% in group B at the time of delivery. Ephedrine infusion was associated with a smaller incidence of nausea (P less than 0.01). Umbilical arterial pH values were not different between the two groups. We conclude that infusion of ephedrine, combined with low volume colloid administration, is a safe alternative to more extensive colloid volume expansion for control of hypotension and provides effective prophylaxis against nausea during extradural Caesarean section in healthy non-labouring mothers.

Adult↗
PubMed1975

Chromosomal damage after intra-articular injection of different colloids of yttrium 90.

Chromosomal damage to circulating lymphocytes occurs following injection of intra-articular radio-isotopes. Differences in the degree of chromosomal damage have been shown with various colloidal forms of yttrium 90, and the severity of these changes has been shown to correlate with the degree of leakage of radio-isotope to the draining lymph node rather than with whole-body irradiation. The long-term significance of these changes is not yet known, but it is clearly prudent to use the colloidal form least associated with chromosomal damage.

Adult↗