Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Colloids”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,693 records · Page 94Linked to original sources
PubMed2002

Visible light induced hydrogen production with Mg chlorophyll-a from spirulina and colloidal platinum.

Photoinduced hydrogen production with Mg chlorophyll-a from spirulina as a visible light photosensitizer by use of three component system consisting of nicotineamide adenine dinucleotide phosphate, reduced form (NADPH) as an electron donor, methylviologen as electron relay reagent and colloidal platinum as hydrogen evolution catalyst was investigated. By the addition of NADPH, the photostability of Mg chlorophyll-a was increased. The effective visible-light induced hydrogen production system with colloidal platinum was established using Mg chlorophyll-a.

Bacterial Proteins↗
PubMed2003

Visible and near-IR light induced biohydrogen production using the system containing Mg chlorophyll-a from Spirulina and colloidal platinum.

Photoinduced hydrogen production with Mg chlorophyll-a from Spirulina as a visible and near-IR light photosensitizer by use of three component system consisting of nicotineamide adenine dinucleotide phosphate, reduced form (NADPH) as an electron donor, methylviologen as electron relay reagent and colloidal platinum as hydrogen production catalyst was investigated. After 4 h irradiation, the amount of hydrogen production with Mg chlorophyll-a and MgTPP, which was artificial model compound for chlorophyll, were c.a. 2.7 and 1.8 micromol, respectively. When the near-IR light was irradiated, little change of hydrogen production was observed. Thus, the effective visible and near IR light induced hydrogen production system with colloidal platinum was established using Mg chlorophyll-a.

Bacterial Proteins↗
PubMed2001

Influence of colloid fluids on polymorphonuclear granulocyte function in vivo.

BACKGROUND: Granulocytes have a role in the immediate immune response. In a previous investigation we could demonstrate in vitro a moderate increase of the complement receptors CR1 (CD35) and CR3 (CD11b/CD18) on the surface of polymorphonuclear neutrophils (PMN) after incubation of whole blood with colloids. To elucidate the clinical significance, we investigated if these changes were also present in vivo. METHODS: The study was performed prior to anaesthesia for orthopaedic surgery. A total of 60 ASA-I patients was evaluated. Patients received in a randomised manner 7 mL/kg of the following solutions: human albumin 5% (HA), gelatine 4% (GEL), hydroxyethylstarch solution 6% with MW 200,000 Da, degree of substitution 0.5 (HES), or Ringer's solution. Prior to the infusion, at the end (30 min) and again 30 min later, blood samples were taken. Blood was incubated with fluorescein-conjugated monoclonal antibodies (CD11b, CD16, CD35, CD62L) and analysed with flow cytometry. RESULTS: HA, GEL, HES, and Ringer's solution failed to induce significant differences in the expression of complement receptors CR1 (CD35) and CR3 (CD11b/CD18), Fc gamma receptor IIIb (CD16), and of L-selectin (CD62L) receptor on the surface of PMN. CONCLUSIONS: Application of colloids like HA, GEL, or HES in moderate amounts shows no short-term effect on adhesion or activation molecules on granulocytes. However, in high doses, infused in situations such as multiple trauma and sepsis, the consequences on the function of PMN may be speculative and require further investigations.

Adult↗
PubMed1986

Effect of colloid volume expansion on glomerular barrier size-selectivity in humans.

Colloid volume expansion magnifies proteinuria in subjects with the nephrotic syndrome. To elucidate this phenomenon, we performed differential solute clearances prior to and following infusion of hyperoncotic albumin in 21 nephrotic subjects and seven healthy controls. Urinary excretion rate and fractional clearance of albumin (radius = 36 A) and immunoglobulin G (radius = 55 A) increased significantly in nephrotic subjects. However, urinary albumin excretion rate was unchanged in controls. The fractional clearances of dextrans of broad size distribution (radii = 28 to 58 A) were markedly altered in both groups following albumin infusion. A heteroporous model which depicts the major portion of the glomerular capillary wall as an isoporous membrane (pore radius approximately 55 A) and the minor portion as a non-discriminatory shunt, revealed the latter to be much more prominent in nephrotic subjects than in controls, and to be enlarged further following albumin infusion. By contrast no increase in pore size of the non-shunt pathway occurred in either group. We infer that enhancement of a pre-existing defect of glomerular size-selectivity in nephrotic subjects accounts, in large part, for exaggerated proteinuria in the colloid volume-expanded state. Increases in glomerular perfusion rate and pressure associated with plasma hypervolemia may mediate this alteration in glomerular membrane-pore structure.

Capillary Permeability↗
PubMed2004

Detection of molecular interactions at membrane surfaces through colloid phase transitions.

The molecular architecture of-and biochemical processes within--cell membranes play important roles in all living organisms, with many drugs and infectious disease agents targeting membranes. Experimental studies of biochemical reactions on membrane surfaces are challenging, as they require a membrane environment that is fluid (like cell membranes) but nevertheless allows for the efficient detection and characterization of molecular interactions. One approach uses lipid membranes supported on solid substrates such as silica or polymers: although the membrane is trapped near the solid interface, it retains natural fluidity and biological functionality and can be implanted with membrane proteins for functional studies. But the detection of molecular interactions involving membrane-bound species generally requires elaborate techniques, such as surface plasmon resonance or total internal reflection fluorescence microscopy. Here we demonstrate that colloidal phase transitions of membrane-coated silica beads provide a simple and label-free method for monitoring molecular interactions on lipid membrane surfaces. By adjusting the lipid membrane composition and hence the pair interaction potential between the membrane-supporting silica beads, we poise our system near a phase transition so that small perturbations on the membrane surface induce dramatic changes in the macroscopic organization of the colloid. We expect that this approach, used here to probe with high sensitivity protein binding events at membrane surfaces, can be applied to study a broad range of cell membrane processes.

Antibodies↗
PubMed2005

Visualisation of natural aquatic colloids and particles -- a comparison of conventional high vacuum and environmental scanning electron microscopy.

The applicability of environmental scanning electron microscopy (ESEM; imaging of hydrated samples) and conventional high vacuum scanning electron microscopy (SEM; imaging of dried samples at high vacuum) for the observation of natural aquatic colloids and particles was explored and compared. Specific attention was given to the advantages and limitations of these two techniques when used to assess the sizes and morphologies of complex and heterogeneous environmental systems. The observation of specimens using SEM involved drying and coating, whereas ESEM permitted their examination in hydrated form without prior sample preparation or conductive coating. The two techniques provided significantly different micrographs of the same sample. SEM provided sharper images, lower resolution limits (10 nm or lower), but more densely packed particles, suggesting aggregation, and different morphological features than ESEM, suggesting artefacts due to drying. ESEM produced less easily visualised materials, more complex interpretation, slightly higher resolution limits (30-50 nm), but these limitations were more than compensated for by the fact that ESEM samples retained, at least to some extent, their morphological integrity. The results in this paper show that SEM and ESEM should be regarded as complementary techniques for the study of aquatic colloids and particles and that ESEM should be more widely applied to aquatic environmental systems than hitherto.

Colloids↗
PubMed2005

A unifying mechanism for all high-temperature Heck reactions. The role of palladium colloids and anionic species.

The Heck reaction has been the subject of intense investigation in the past decade. Many new types of catalysts have been developed in addition to the existing palladium/phosphine complexes. Prominent among these are palladacycles, pincers, several types of heterogeneous palladium catalysts, colloids and ligand-free palladium, usually in the form of Pd(OAc)2. Most of the newer types function only at higher temperatures, typically between 120 and 160 degrees C. It has been shown that irrespective of the catalyst precursor, none of these catalysts are stable at these high temperatures. They all have a tendency to form soluble palladium(0) colloids or nanoparticles, certainly with less reactive substrates such as aryl bromides or chlorides. The Heck reaction takes place by attack of the arylating agent on the palladium atoms in the outer rim of the nanoparticles. This leads to formation of monomeric or dimeric anionic palladium complexes that undergo the usual steps of the Heck mechanism as described by Amatore and Jutand.

Acetates↗
PubMed2006

Directing the self-assembly of nanocrystals beyond colloidal crystallization.

This article gives an overview of recent progress in the self-assembly of nanocrystals. Classic self-assembly of nanocrystals, so-called colloidal crystallization driven by van der Waals interactions, is highlighted first with an emphasis on the recent realization of binary colloidal crystals. Next, new developments in the integration of nanocrystals into clusters based on electrostatic interactions, hydrogen bonding and dipole-dipole interactions are summarized, shedding light on the defined control of the interactions between the nanocrystals. Finally, the fabrication of heterogenous nanocrystals, obtained via either phase selective modification at the water/oil interface or facet-selective crystal growth on non-spherical nanocrystals is discussed. These last materials may provide significant building blocks for mimicking molecular self-assembly.

Adsorption↗
PubMed2001

Sentinel node biopsy with technetium-99m colloidal rhenium sulphide in patients with breast cancer.

BACKGROUND: Sentinel node biopsy is emerging as a technique to replace routine axillary lymph node dissection. The lymphatic mapping technique is still at a developmental stage and no standard technique exists. This study used technetium-99m colloidal rhenium sulphide with a mean particle size of 100 (range 50-200) nm for sentinel node mapping. METHODS: Eighty-seven patients with breast cancer, but no clinical evidence of axillary metastasis, were studied. One day before operation technetium-99m colloidal rhenium sulphide was injected at four points into breast tissue surrounding the tumour. Lymphoscintigraphy was performed 2 h after injection, and surgery was usually performed after 20 h. A hand-held gamma probe guided sentinel node biopsy. RESULTS: Lymphoscintigraphy revealed axillary hot spots in all patients. During operation, the sentinel node was identified in all 87 patients (100 per cent). The number of sentinel nodes per patient ranged from 1 to 5 (mean 2). Metastatic sentinel nodes were identified in 37 of 87 patients. There were no false negatives. CONCLUSION: This study suggests that technetium-99m rhenium sulphide is a suitable agent for sentinel node mapping in patients with breast cancer.

Adult↗
PubMed2003

High-resolution backscatter electron imaging of colloidal gold in LVSEM.

High-resolution backscatter electron (BSE) imaging of colloidal gold can be accomplished at low voltage using in-lens or below-the-lens FESEMs equipped with either Autrata-modified yttrium aluminium garnet (YAG) scintillators doped with cerium, or with BSE to secondary electron (SE) conversion plates. The threshold for BSE detection of colloidal gold was 1.8 keV for the YAG detector, and the BSE/SE conversion was sensitive down to 1 keV. Gold particles (6, 12 and 18 nm) have an atomic number of 79 and were clearly distinguished at 500,000x by materials contrast and easily discriminated from cell surfaces coated with platinum with an atomic number of 78. BSE imaging was relatively insensitive to charging, and build up of carbon contamination on the specimen was transparent to the higher energy BSE.

Electrons↗
PubMed2003

Colloid osmotic pressure after hemorrhage and replenishment with Oxyglobin Solution, hetastarch, or whole blood in pregnant sheep.

OBJECTIVE: To compare plasma colloid osmotic pressure (COP) of both maternal and fetal blood, before and after hemorrhage, and replenishment with Oxyglobin Solution (Biopure Corporation, Cambridge, MA, USA), hetastarch or whole blood in pregnant ewes. STUDY DESIGN: Prospective, randomized study. ANIMALS: A total of 17 adult Rambouillet ewes at 131 (128-133) [median (minimum, maximum)] days gestation, weighing 56 (46, 63) kg. METHODS: Ewes and fetuses were chronically instrumented with catheters in a maternal jugular vein, maternal carotid artery and fetal femoral artery. Twenty milliliters per kilograms of blood were removed from each ewe over 1 hour. The ewes were then given 20 mL kg(-1) of either Oxyglobin Solution (n = 5), hetastarch (n = 6), or autologous whole blood (n = 6) IV. Maternal plasma COP was measured before hemorrhage, after hemorrhage, after replenishment, and 1 and 2 hours later. Fetal plasma COP was measured after maternal hemorrhage and 2 hours after maternal volume replenishment. RESULTS: Median COP of all ewes before hemorrhage was 20 (16, 24) mm Hg and after hemorrhage (p < 0.05), decreased to 16 (11, 19) mm Hg. After volume replenishment, the COP of the Oxyglobin Solution group was 22 (21, 25) mm Hg, the autologous whole blood group was 17 (16, 22) mm Hg and the hetastarch group was 20 (17, 21) mm Hg. The COP of the Oxyglobin Solution group was significantly greater (p < 0.05) than the COP of the hetastarch group immediately and 60 minutes after volume replenishment, and greater (p < 0.05) than that of the autologous whole blood group at 60 minutes after volume replenishment. The COP of all the fetuses after maternal hemorrhage was 16 (12, 19) mm Hg and at 120 minutes after maternal volume replenishment was 15 (11, 18) mm Hg. There were no differences in COP between or within any of the fetal groups. CONCLUSIONS: When used to treat blood loss, Oxyglobin Solution increases plasma COP more than an equal volume of hetastarch in the first hour following administration. Maternal administration of Oxyglobin Solution did not alter fetal COP. CLINICAL RELEVANCE: Oxyglobin Solution is a more potent colloid than hetastarch. Oxyglobin Solution did not appear to translocate fluid from the fetal to maternal circulation.

Animal Diseases↗
PubMed1999

Colloidal bismuth pectin: an alternative to bismuth subcitrate for the treatment of Helicobacter pylori--positive duodenal ulcer.

BACKGROUND: Bismuth triple therapy provides consistently good results in Helicobacter pylori eradication worldwide, whereas quadruple therapy using a combination of omeprazole and bismuth triple regimen has produced cure rates in excess of 90%. The prevalence of metronidazole-resistant strains was 26.8% in our area. Colloidal bismuth pectin (CBP) is a new, lower-priced bismuth salt made in China. The purpose of this study was to investigate the efficacy and safety of CBP triple and quadruple regimens in the treatment of H. pylori-positive duodenal ulcer. MATERIALS AND METHODS: In this prospective trial, 205 patients with H. pylori-positive duodenal ulcer were allocated randomly to receive one of four regimens: metronidazole, 200 mg; amoxicillin, 250 mg; and colloidal bismuth subcitrate (CBS), 120 mg (group 1), or CBP, 100 mg qid (group 2) for 2 weeks, then continued CBS, 240 mg, or CBP, 200 mg bid for a further 2 weeks. A quadruple regimen using a combination of omeprazole, 20 mg bid, and CBS triple therapy (group 3) or CBP triple therapy (group 4), respectively, was given to patients for 1 week, followed by omeprazole, 20 mg once daily for a further 3 weeks. Further endoscopy was performed at least 4 weeks after cessation of the treatment. H. pylori status was determined by histology, a 14C urea breath test, and a urease test. RESULTS: The per-protocol H. pylori cure rates were 85% (22 of 26 patients), 90% (35 of 39), 96% (46 of 48), and 95% (75 of 79) for groups 1 through 4. In the intention-to-treat analysis, cure rates were 79% (22 of 28), 83% (35 of 42), 90% (46 of 51), and 89% (75 of 84), respectively. The cure rates of quadruple therapy were higher than those of triple therapy; an 8.2% difference was not statistically significant (95% confidence interval [CI], 2.3-18.7%). The ulcer-healing rates were 88%, 87%, 98%, and 97%, respectively, for groups 1 through 4. The ulcer pain was relieved more rapidly in quadruple- than in triple-therapy regimens. Two patients discontinued treatment prematurely owing to drug-related side effects. CONCLUSION: One-week quadruple therapy is highly effective and safe in H. pylori eradication in Chinese patients. CBP is as effective as CBS.

Adolescent↗
PubMedDate not supplied

The potentiation of "incomplete" mouse monoclonal anti-Lea agglutination with colloids.

Mouse monoclonal anti-Lea produced in this center was found to agglutinate only Le(a+) red cells which had been modified with proteases. In order to provide a stable medium in which the monoclonal anti-Lea would directly agglutinate unmodified red cells, the potentiating effect of a variety of colloids was assessed. Satisfactory results were obtained when 10 percent (wt/vol) dextran and 2 percent (wt/vol) bovine serum albumin were added to the culture supernatant containing anti-Lea. It is suggested that direct hemagglutination mediated by these colloids resulted from a combination of increased antibody uptake by Le(a+) red cells and change in the shape of these red cells induced by dextran.

Antibodies, Monoclonal↗
PubMed2004

Anterior transcallosal approach to the colloid cysts of the third ventricle: case series and review of the literature.

OBJECTIVES: To evaluate the results of the anterior transcallosal approach to the colloid cysts of the third ventricle. PATIENTS AND METHODS: A retrospective analysis of the patients operated on between 1986 and 2003 was carried out. There were 19 patients (10 female, 9 male) with a median age of 43. The main presenting symptom was headache. One of the patients presented with acromegaly due to a pituitary tumor. The size of the cysts ranged from 15 to 43 mm. An anterior transcallosal approach was used in all patients. RESULTS: The cysts were excised totally in all cases. Postoperatively no recent memory loss has been detected in any patient. One patient with hemorrhagic papil stasis experienced temporary visual worsening. In one patient with hydrocephalus a ventriculoperitoneal shunt was needed. One patient with postoperative superior frontal gyrus venous infarction had a seizure. The follow-up period was from 1 month to 13 years (mean 5.2 years). To date, there has been no recurrence so far. CONCLUSION: The anterior transcallosal approach is a safe method for the treatment of third ventricular colloid cysts.

Adolescent↗
PubMed1984

Internalization of colloidal gold-labelled insulin complexes into cultivated human smooth muscle cells.

The binding and internalization of colloidal gold-labelled insulin complexes into cultivated human arterial smooth muscle cells was studied. We could demonstrate that the colloidal gold-labelled insulin complex was bound to specific receptors on the cell surface of smooth muscle cells and internalized after 30 min at 20 degrees C. The gold-labelled insulin complexes entered the cell via vesicles and escaped from them in the cytoplasm. The biological activity of the complexes was determined by measuring their effect on DNA synthesis in smooth muscle cells and incorporation of (14C)-glucose into isolated fat cells. The binding characteristics of the complexes were examined by competitive inhibition of 125I-insulin binding to isolated fat cells in the presence of increasing concentrations of gold-labelled insulin complexes or unlabelled insulin. The gold-labelled insulin complex showed a growth promoting and metabolic effect and was able to compete with 125I-insulin for its binding sites.

Adipose Tissue↗
PubMed1991

Acute gestational pyelonephritis: the impact on colloid osmotic pressure, plasma fibronectin, and arterial oxygen saturation.

Acute gestational pyelonephritis infrequently leads to nonhydrostatic permeability pulmonary edema known clinically as acute respiratory distress syndrome (ARDS). In this form of ARDS, sepsis is considered the primary cause of pulmonary dysfunction. Decreases in colloid osmotic pressure, plasma fibronectin, and arterial oxygen saturation are associated with a worsening prognosis in septic conditions. We sought to investigate the changes in these parameters with acute gestational pyelonephritis to gain insight into the factors that may place the patient at risk for sepsis-related morbidity. Colloid osmotic pressure, plasma fibronectin, and arterial oxygen saturation via pulse oximetry were prospectively measured during the inpatient treatment of 17 pregnant patients with acute gestational pyelonephritis. All three parameters achieved their nadir within 24 hours of hospitalization and the initiation of therapy. Although no patient developed significant pulmonary dysfunction, we believe that patient susceptibility for pulmonary edema and general morbidity could be maximal in the first 24 hours after therapy. Future studies using a larger number of patients may identify one or more of these laboratory parameters as helpful in identifying gravid patients who are at risk of developing gestational ARDS.

Acute Disease↗
PubMedDate not supplied

[Determination and clinical significance of colloid osmotic pressure in pediatric patients].

The clinical significance of colloid osmotic pressure (COP) in transcapillary fluid exchange and water homeostasis in health and disease is described. Under pathophysiological circumstances measurement of COP should be preferred to COP value calculation. After extensive COP experiences in critically ill adults and numerous refinements in COP monitoring technology, COP studies in neonates and paediatric intensive care patients have been published recently. In these patients hypovolaemia and need of volume replacement therapy are often associated with an increase in capillary permeability. Therefore prevention of general and interstitial colloid and fluid overload is a permanent challenge in the care of the young critically ill patient; e.g. in a case report. Consequently regular COP measurements should be considered in paediatric intensive care, especially in case of oncotic volume replacement therapy.

Capillary Permeability↗