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At least 217 records · Page 12Linked to original sources
PubMed1986

DNA binding and adduct formation of 7,12-dimethylbenz[a]-anthracene by rat mammary epithelial cell aggregates in vitro.

Freshly isolated mammary epithelial cell aggregates from female Sprague-Dawley rats metabolized 7,12-dimethylbenz-[a]anthracene (DMBA) to bay-region anti- and syn-dihydrodiolepoxides that bound to deoxyguanosine and deoxyadenosine residues in cellular DNA. After 24 h of incubation 68% of the DMBA (0.4 micrograms/ml) was metabolized and 58% of the extracellular metabolites were water-soluble. DMBA-DNA binding increased rapidly during the initial 24 h of incubation. Formation of the bay-region syn-dihydrodiolepoxide:deoxyadenosine adduct increased linearly throughout the 24 h, whereas formation of deoxyadenosine and deoxyguanosine adducts with the bay-region anti-dihydrodiolepoxide increased rapidly following a delay of 12 h.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed2003

Intraparenchymal nevus cell aggregates in lymph nodes: a possible diagnostic pitfall with malignant melanoma and carcinoma.

It is well documented that nevus cells can be found within the fibrous capsule and trabeculae of lymph nodes; however, it is less well known that nevus cells can also be found in the lymph node parenchyma. We report the findings in 13 cases of nevus cell aggregates located within the cortical and/or medullary parenchyma of lymph nodes. Seven of the 13 patients had a primary diagnosis of melanoma, three had no known malignancy, one had breast carcinoma, one had adnexal carcinoma of the skin, and one had squamous cell carcinoma of the tonsil. Of the seven patients with melanoma, four had axillary lymph node dissections and three had inguinal lymph node dissections. The patient with adnexal carcinoma had metastatic carcinoma in 14 of 20 lymph nodes that had been dissected; one of them also had intraparenchymal nevus cells. The patient with squamous cell carcinoma of the tonsil had an intraparenchymal nevus cell aggregate in one of the 21 dissected lymph nodes; all 21 were negative for carcinoma. Nests of intraparenchymal nevus cells ranged from clusters of only a few cells up to 2.1-mm aggregates. No mitotic figures, prominent nucleoli, or lymphatic-vascular invasion were detected in any of the melanocytic aggregates. The melanocytic cells of the nevus cell aggregates expressed S-100 protein and/or MART-1 but not gp100 protein (HMB-45). Less than 1% of the nevus cells expressed Ki-67. The purpose of this study was to draw attention to the finding of nevus cells in the parenchyma of lymph nodes and to alert pathologists to this as a potential diagnostic pitfall, especially in patients with concurrent melanoma or carcinoma. Awareness that nevus cells can be present in nodal parenchyma, analysis of their morphologic features (including comparison with any previous or existing melanoma or carcinoma), and immunophenotyping will help pathologists to establish the correct diagnosis in most instances.

Adult↗
PubMed2002

Postexercise red cell aggregation is negatively correlated with blood lactate rate of disappearance.

In three separate studies, we have observed that the rise in blood lactate during exercise is correlated to blood viscosity and red cell aggregation. Whether these results were related to an effect of blood rheology on lactate production by muscles or on lactate disappearance remains unknown. The modelling of postexercise lactate kinetics allows a fair evaluation of lactate production by muscles (gamma1) and lactate disappearance (gamma2), the latter being easily measurable with simplified protocols. We thus investigated the relationships between pre- and postexercise blood rheology and gamma2. Ten subjects (2 female and 8 males; age 16-45 yr, weight 62-106.5 kg) exhibiting a wide range of gamma2 (from 2 to 7.7x10(-2) min(-1)) underwent a maximal exercise-test with postexercise calculation of gamma2 with the simplified formula gamma2=0.0724+0.755(Lac8-Lac20)/(Lac8.Deltat)-0.00684Lac20 where Lac8 and Lac20 are lactate concentrations 8 and 10 min after exercise stop at the level of VO2max, as previously reported. During exercise whole blood viscosity eta(b) increased (+15%, p<0.01) due to a rise in hematocrit (p<0.05) and plasma viscosity (+0.08+/-0.03 mPa.s, p<0.05), while red cell rigidity was unchanged. Red cell aggregation (Myrenne M1) increased by 11% (p<0.05). Postexercise M1 (measured at VO2max) was the only hemorheologic parameter correlated to gamma2 (r=-0.697, p=0.037). We find once again a statistical relationship between lactate at exercise and red cell aggregation. Microcirculatory adaptations influenced by red cell aggregation may influence lactate disposal (as reflected by gamma2), adding its effect to that of the balance between carbohydrates and fat oxidation which is the major determinant of blood lactate concentrations at exercise in physiological conditions.

Adult↗
PubMed1999

Cadmium content of the marine sponge Microciona prolifera, other sponges, water and sediment from the eastern Florida panhandle: possible effects on Microciona cell aggregation and potential roles of low pH and low salinity.

Marine sponges from shallow bays and estuaries along the Florida panhandle contained cadmium (Cd), 1.78-27.9 microg g(-1) (dry weight). Levels > 7 microg g(-1) were never found in a variety of other benthic invertebrates. Water levels of Cd were of the order 0.22-0.43 microg ml(-1) and did not differ significantly between the two study areas (Panacea and St. Joseph Bay). Cd in organic sediment however, was significantly (P = 0.033) higher around Panacea (0.343 +/- 0.063 S.E.M.) than in St. Joseph Bay (0.18 +/-0.223 S.E.M.). Salinity of 10 and pH 6.5 were recorded following heavy rains, and can constitute a hostile environment for these organisms. Temporal variations of Cd and Cu but not Zn were observed in Microciona prolifera over a period of 2 years in St. Joseph Bay, and a negative correlation was observed between Cd content and the Ca(2+)-induced aggregation of Microciona cells suspended in Ca2+/Mg(2+)-free artificial seawater. Cells unresponsive to Ca2+ aggregated in response to releasers of Ca2+ from internal stores (thapsigargin, A23187 and tetredecylamine), suggesting that they were viable but dormant. In vitro studies showed that Cd2+ is about equipotent with Ca2+ in inducing aggregation of Microciona cells, whereas lower concentrations (1-2 x 10(-3) M), added 10 min before inducing aggregation with CaCl2, inhibited aggregation, possibly by blocking Ca2+ uptake. Microciona contained a metallothionein (MT)-like protein. Taken together these results suggest that naturally-acquired Cd may interfere with cell regulatory processes in Microciona. Possible effects of low pH and salinity on Cd uptake and detrimental effects on cell function are discussed.

Animals↗
PubMed1996

Red blood cell aggregability is increased by aspirin and flow stress, whereas dipyridamole induces cell shape alterations: measurements by digital image analysis.

We evaluated the influence of pretreatment with aspirin in vitro, alone or combined with dipyridamole, on red cell aggregability. Samples were tested before and after being exposed to well-defined flow conditions. An aggregation rate was estimated through digital analysis of light microscopy images. Red cells of untreated blood that had been exposed to flow showed a higher aggregation rate (38.54 +/- 1.63 vs. 27.52 +/- 1.36; P < 0.05). This effect was not observed in the absence of platelets. Treatment with aspirin induced a high aggregation rate, with or without exposure to flow conditions. Dipyridamole alone or combined with aspirin provoked echinocytosis, disturbing the rouleaux arrangement (rates ranging from 11.25 +/- 1.91 - 13.62 +/- 1.62). Washing red cells after treatment restored about 90% of echinocytes to their biconcave shape, but aggregation rate did not recover in parallel. These results highlight the influence of red cell-platelet interactions in the regulation of haemostasis and show how therapeutic agents can interfere with rheological phenomena.

Aspirin↗
PubMed1994

Cell-binding peptides conjugated to poly(ethylene glycol) promote neural cell aggregation.

We have developed a method for promoting cell aggregation with bifunctional macromolecules synthesized by coupling cell-binding peptides to an inert, water-soluble polymer. The peptides Arg-Gly-Asp (RGD) and Tyr-Ile-Gly-Ser-Arg (YIGSR) were conjugated through their amino termini to both ends of linear poly(ethylene glycol) (PEG), producing bifunctional hybrid polymers: RGD-PEG-RGD and YIGSR-PEG-YIGSR. RGD-PEG-RGD promoted aggregation of mechanically-dissociated fetal brain cells, pheochromocytoma cells (PC12), and neuroblastoma cells maintained in rotation culture at 37 degrees C. Enhanced aggregation was noticeable within 10 minutes and became more pronounced over the next several hours: after 7-9 hours, the mean aggregate volume was up to 10 times larger than the mean volume produced in suspensions containing unmodified PEG. Similar results were obtained with YIGSR-PEG-YIGSR and PC12 cells. Enhancement in aggregation correlated with the ability of soluble RGD or YIGSR to inhibit cell adhesion to surfaces coated with laminin or fibronectin. This method for promoting aggregation may be useful for large scale culture of anchorage dependent cells, eliminating the need for microcarriers. In addition, aggregates formed by this method may be suitable for use in artificial organs or as cell transplants for tissue regeneration.

Adrenal Gland Neoplasms↗
PubMed1979

Tumor cell aggregation and mode of cancer spread in linitis plastica type of gastric carcinoma.

Spread of tumor cells in linitis plastica type of gastric carcinoma was studied in relation to features of tumor cell aggregation which were classified into two types: free-cell type and small nest type. Free-cell type was accompanied by a larger amount of fibrous stroma in submucosal layers than in small nest type. In the gastric wall lymphatics and regional lymph nodes, small nest types was more prominent than the free-cell type. Lymphatic permeation was noted predominantly in the submucosa. In the mucosa, both free-cell and small nest types were frequently present. In carcinoma with free-cell type predominance, diffuse infiltration with infrequent lymphogenous spread was noted, while in carcinoma with small nest type predominance, spread via the lymphogenous route was observed more frequently. The mode of cancer spread in this type of carcinoma appeared to be affected by the type of tumor cell aggregation dominant in the mucosa.

Adenocarcinoma, Scirrhous↗
PubMed1997

[Reversible red cell aggregation in children with insulin-dependent diabetes mellitus].

Red cell aggregation has been studied by photometry in 47 children with insulin-dependent diabetes mellitus. The disease was associated with boosting of reversible red cell aggregation, which was most of all expressed during metabolic decompensation with ketoacidosis. When metabolic subcompensation was attained, this parameter did not completely normalize and still had to be corrected.

Adolescent↗
PubMed1993

Cigarette smoking increases white blood cell aggregation in whole blood.

We studied the effect of chronic cigarette smoking on white blood cell aggregation, increased aggregation predisposes to microvascular occlusion and damage. Current smokers had significantly increased white blood cell aggregation when compared with non smokers. The presence of chronically activated white blood cells in current smokers may be relevant in the pathogenesis of ischaemic vascular disease.

Adolescent↗
PubMed2005

The use of multi-parameter flow cytometry to study the impact of limiting substrate, agitation intensity, and dilution rate on cell aggregation during Bacillus licheniformis CCMI 1034 aerobic continuous culture fermentations.

The main objective of this work was to establish those factors either physical (power input) or chemical (limiting substrate or dilution rate) that enhance cell aggregation (biofilm or floc formation) and cell physiological state during aerobic continuous cultures of Bacillus licheniformis. Glucose-limited steady-state continuous cultures growing at a dilution rate between 0.64 and 0.87/h and 1,000 rpm (mean specific energy dissipation rate (epsilonT) = 6.5 W/kg), led to the formation of a thin biofilm on the vessel wall characterized by the presence of a high proportion of healthy cells in the broth (after aggregate disruption by sonication) defined as having intact polarized cytoplasmic membranes. An increased epsilonT (from 6.5 W/kg to 38 W/kg) was found to hinder cell aggregation under carbon limitation. The carbon recovery calculated from glucose indicated that additional extracellular polymer was being produced at dilution rates >0.87/h. B. licheniformis growth under nitrogen limitation led to floc formation which increased in size with dilution rate. Counter-intuitively the flocs became more substantial with an increase in epsilonT from 6.5 W/kg to 38 W/kg under nitrogen limitation. Indeed the best culture conditions for enhanced metabolically active cell aggregate formation was under nitrogen limitation at epsilonT = 6.5 W/kg (leading to floc formation), and under carbon limitation at a dilution rate of between 0.64 and 0.87/h, at epsilonT = 6.5 W/kg (leading to vessel wall biofilm formation). This information could be used to optimize culture conditions for improved cell aggregation and hence biomass separation, during thermophilic aerobic bioremediation processes.

Aerobiosis↗
PubMed1989

Histological evidence of natural killer cell aggregation against malignant melanoma induced by adoptive immunotherapy with lymphokine-activated killer cells.

Adoptive immunotherapy with lymphokine-activated killer (LAK) cells and systemic administration of recombinant Interleukin-2 (RIL-2) was carried out in a case of malignant melanoma with lung metastases. Histological specimens from the lung showed a metastatic melanoma heavily invaded by atypical lymphoid cells with convoluted nuclei of varying size. Immunohistochemistry revealed that these cells had the characteristic exclusively of natural killer cell (Leu-7+). Nodules of these cells mimicked the appearance of non-Hodgkin's lymphoma of pleomorphic type. Molecular cytogenetic analysis, however, showed the absence of rearranged bands for the T-cell receptor beta-chain gene, indicating the absence of T-cell clones. At autopsy, 1 month after the LAK therapy, the heavy invasion of convoluted cells had disappeared. These findings clearly indicate that the LAK cell plus RIL-2 therapy induced Leu-7+ lymphoid cells, phenotypically suggestive of natural killer cell aggregation in the tumours.

Cell Aggregation↗
PubMed1996

[The effect of cytoskeleton modification on the process of trypsin-induced cell aggregation].

Studies were performed on the influence of cytoskeleton modification (by colchicine, vinblastine, and cytochalasin B, and by neoplastic transformation) on cell aggregation induced by small trypsin concentrations (the final concentrations equal to 1-100 mg/ml) added to a suspension of chick embryo fibroblasts dispersed from a monolayer with EDTA. It was shown that alteration of microfilaments resulted in the loss of the ability of plasma membranes to structural rearrangements. It is suggested that aggregation of these cells is realized due to a gradual exposure of adhesive sites along with proteolytic splitting of protein components of plasma membranes.

Animals↗
PubMed1984

Cholesterol-induced growth stimulation, cell aggregation, and membrane properties of ascites tumor cells in culture.

Ascites tumor cells can be cultivated at a reduced serum concentration if cholesterol (2.50 mg per 100 ml of medium) is added to the culture medium. At serum concentrations of 3%, optimal growth properties are obtained; below 3%, cell cultures usually perish after a few days. Cells grown in the presence of added cholesterol have an elevated content of this molecule per cell as well as in the plasma membrane, and they also show a cholesterol concentration-dependent rate of proliferation. Precursors of the cholesterol-biosynthetic pathway like mevalonic acid, added in mM amounts, or squalene and lanosterol cannot be substituted for cholesterol itself. This is due to the observation that the biosynthetic pathway is blocked at the stage of lanosterol conversion to cholesterol. Cholesterol de novo synthesis from acetate is regulated by the cholesterol content of the cells, which also affects the production of ubiquinone and dolichol. Growth factors such as insulin, prostaglandin F2 alpha, and transferrin added to the medium do not mimic the cholesterol-induced effect. Distribution of DNA during cell cycle and the cell density-dependent reduction in macromolecule synthesis is very similar to the control cells. In contrast, cells without added cholesterol show reduced growth properties accompanied by the accumulation of cells in the mitotic and G2 phase. The cholesterol/phospholipid ratio of the plasma membranes of cholesterol-rich cells is about 15% lower than of the control cells and 40% higher compared to the cholesterol-poor cells, which, however, does not significantly alter the membrane fluidity between the cholesterol-rich and -poor cells as revealed by fluorescence polarization measurements. The most dramatic behavior of the cholesterol-rich cells is their tendency to form aggregates, which is demonstrated either by concanavalin A-induced agglutination or by cell density-dependent aggregation shown by interference microscopy in vivo.

Agglutination↗
PubMed1991

Selective sensitivity to methylmercury of specific cell aggregates and validity of the "nurse" cell concept.

Meristematic cells of carrot (Daucus carota--Ca68-10) were grown in a heterogeneous suspension culture in the absence of (2,4-dichlorophenoxy)acetic acid in 71-V medium in the dark. Freshly inoculated cell cultures were treated daily with methyl mercury for the first 4 days and harvested on Day 7. The cultures were separated (by selective filtration) into groups of aggregates varying in size from 44 to 900 microns. Methyl mercury severely decreased the cell mass of the dominant (300-microns) fraction. When separate aggregates were cultured (44 to 900 microns) and treated as before, the inhibition of the 300 microns fraction was more evident. Separately cultured cell groups of 200- or 300-microns size developed into larger heterogeneous populations and contained the dominant 300-microns size group which was the most sensitive to methyl mercury. Other cell groups (900-, 500-, and 44-microns) failed to produce a large heterogeneous cell population when cultured separately. Without the 300-microns-sized aggregate, neither the whole culture nor the separate aggregates culture (900, 500, or 44 microns) could survive, suggesting the "nurse" cell role of the 300-microns cell group.

2,4-Dichlorophenoxyacetic Acid↗
PubMed1986

Effect of modification of membrane phospholipid composition on phospholipid methylation in aggregating cell culture.

The effect of the presence of nitrogenous bases in the growth medium of fetal rat brain aggregating cell cultures was investigated. The presence of either N-methylethanolamine (MME) or N,N-dimethylethanolamine (DME) in the growth medium resulted in significant increase of the corresponding phospholipid, phosphatidyl-N-monomethylethanolamine (PMME) or phosphatidyl-N,N-dimethylethanolamine (PDME). They represented 28% and 32% of the total phospholipids, respectively. The presence of the new phospholipids was accompanied by a significant decrease of phosphatidylethanolamine (PE) and phosphatidylcholine (PC). Cells grown in the presence of ethanolamine or choline had only barely detectable amounts of PMME and PDME. Intact cells previously grown with the bases were incubated with [methyl-3H]methionine. Incubation of cells previously grown in presence of the bases MME and DME resulted in a marked increase of radioactivity in the corresponding phospholipids possessing one additional methyl group, PDME and PC respectively. The incorporation of S-adenosyl[methyl-3H]methionine (AdoMet) was examined in cell homogenates incubated in presence or absence of either PMME or PDME acceptors. The addition of these exogenous phospholipids caused a three-or fourfold stimulation of radioactivity incorporated into the total phospholipids of cells grown in the absence of nitrogen bases. The cells grown in presence of either MME or DME in the culture medium did not show an increased incorporation of methyl groups from AdoMet into the total phospholipids after addition of exogenous acceptors. This work suggests that MME and DME incorporated into the corresponding phospholipids function as effective substrates for phospholipid-N-methylation.

Animals↗
PubMed2006

Purification of granulosa cells from human ovarian follicular fluid using granulosa cell aggregates.

Human follicular fluid can provide a source of human granulosa cells for scientific study. However, removing potentially contaminating cells, such as white and red blood cells, is important for molecular and in vitro studies. We have developed a purification technique for human granulosa cells based on the selection of cellular aggregates. Human granulosa cells from 21 IVF patients were collected. A 50% Percoll gradient was used to remove red blood cells, and granulosa cell aggregates were collected, washed and processed for histology, electron microscopy, flow cytometry analysis, cell culture and RNA extraction. Granulosa cell aggregates were found to be homogeneous and free of white blood cells after histological and electron microscopic analysis. White blood cell contamination, measured by flow cytometry, was found to be between 2 and 4%. Polymerase chain reaction analysis revealed expression of known human granulosa cell genes and a white blood cell marker. Human granulosa cells grown in vitro showed flattened fibroblast-like morphology with lipid droplets consistent with previous reports. Cultured cells expressed the FSH receptor. Selection of human granulosa cell aggregates following centrifugation through a Percoll gradient provides an efficient method of selecting granulosa cells, suitable for both molecular and in vitro studies.

Adult↗