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PubMed1975

Studies on the modification of the cellular response to injury. II. Electron microscopic studies on the protective effect of acidosis on anoxic injury of Ehrlich ascites tumor cells.

Extracellular acidosis (ph 5.9 to 6.5) was found to be significantly retard the subcellular response of Ehrlich ascites tumor cells (EATC) to anoxic injury. The cells initially showed a reversible stage of cell injury with diffuse mitrochondrial condensation and swelling of endoplasmic reticulum (ER) at pH 7.9 by 1 h, while by 3 h at this pH all cells showed high amplitude and intramatrical flocculent densities of mitochondria, and fragmentation of membrane systems. At pH 7.4 cells were normal at 15 min., the mitochondria were condensed as above by 1 h, some cells still showed condensed mitochondria and dilated ER while others showed high amplitude swelling of mitochondria by 3 h and all cells showed irreversible changes by 4 h. At pH 5.9 to pH 6.5 mitochondria remained condensed until 3 h and only by 6 h did some cells show high amplitude swelling, whereas most cells showed persistent mitrochondrial condensation. Not until 8 h did all cells show high amplitude swelling of mitochondria. Furthermore, ultrastructural differences in the pattern of necrosis were seen at the lower pH values consisting of greater density of the cell sap, irregularly dispersed flocculent densities in apposition to fragmented cytoplasmic membranes and in mitochondria, and more prominent persistent clumping of nuclear chromatin.

Acidosis↗

PubMed2005

Assessing the detoxication efficiencies of wastewater treatment processes using a battery of bioassays/biomarkers.

A battery of in vitro bioassays, including a Neutral Red (NR) assay using MCF-7 cells for predicting cytotoxic chemicals, an ethoxy resorufin-O-deethylase (EROD) activity assay using H4IIE cells to check for dioxin-like chemicals, and a recombinant gene yeast assay for screening estrogenic chemicals, was conducted to assess the removal efficiencies of trace toxic chemicals by different treatment processes in the waste water treatment plant (WWTP). The effluents were extracted by solid phase extraction (SPE) and were fractionated into three fractions based on polarities. The battery of bioassays was performed for each fraction. In the battery, the toxicities of the effluents were described according to their modes of actions (MOA) or biomarkers and the properties of the toxic chemicals were categorized by their polarities and MOAs. The proposed procedure could be used as a tool to diagnose the toxic characteristics of the complicate mixture. The results showed that cytotoxic, dioxin-like and estrogenic chemicals could be detected in all samples. In the influent, cytotoxic and dioxin-like chemicals were mainly in polar fraction and estrogenic chemicals were in non-polar and moderate-polar fractions. The secondary treatment (active sludge) could remove a small amount of these toxicants. Among different types of advanced treatments, flocculation was good enough to remove most of the cytotoxic chemicals and a combination of flocculation, ozone oxidation, and post-biological treatment could eliminate most of the dioxin-like and estrogenic chemicals.

Animals↗

PubMed1997

Bioremediation of pentachlorophenol-contaminated soil by bioaugmentation using activated soil.

The use of an indigenous microbial consortium, pollutant-acclimated and attached to soil particles (activated soil), was studied as a bioaugmentation method for the aerobic biodegradation of pentachlorophenol (PCP) in a contaminated soil. A 125-l completely mixed soil slurry (10% soil) bioreactor was used to produce the activated soil biomass. Results showed that the bioreactor was very effective in producing a PCP-acclimated biomass. Within 30 days, PCP-degrading bacteria increased from 10(5) cfu/g to 10(8) cfu/g soil. Mineralization of the PCP added to the reactor was demonstrated by chloride accumulation in solution. The soil-attached consortium produced in the reactor was inhibited by PCP concentrations exceeding 250 mg/l. This high level of tolerance was attributed to the beneficial effect of the soil particles. Once produced, the activated soil biomass remained active for 5 weeks at 20 degrees C and for up to 3 months when kept at 4 degrees C. The activated attached soil biomass produced in the completely mixed soil slurry bioreactor, as well as a PCP-acclimated flocculent biomass obtained from an air-lift immobilized-soil bioreactor, were used to stimulate the bioremediation of a PCP-impacted sandy soil, which had no indigenous PCP-degrading microorganisms. Bioaugmentation of this soil by the acclimated biomass resulted in a 99% reduction (from 400 mg/kg to 5 mg/kg in 130 days) in PCP concentration. The PCP degradation rates obtained with the activated soil biomass, produced either as a biomass attached to soil particles or as a flocculent biomass, were similar.

Biodegradation, Environmental↗

PubMed1999

Analysis of the genes activated by the FLO8 gene in Saccharomyces cerevisiae.

It is thought that the FLO8 gene encodes a transcriptional activator of the dominant flocculation gene FLO1 in Saccharomyces cerevisiae. To determine other genes which are regulated by FLO8, a detailed comparison of the transcripts from the FLO8 and Deltaflo8 strains was carried out. In addition to the FLO1 gene, it was found that transcription of the FLO11 and STA1 genes is positively regulated by FLO8. In flo8 strains, not only transcripts of the FLO11, STA1, and FLO1 genes but also invasive growth, extracellular glucoamylase production, and flocculation were undetected. From these results, it is suggested that FLO8 regulates these characteristics via the transcriptional regulation of the FLO11, STA1, and FLO1 genes.

Base Sequence↗

PubMed2002

Enteroclysis in adult celiac disease: diagnostic value of specific radiographic features.

The purpose of this study was to compare the diagnostic accuracy of various radiographic findings at enteroclysis in adult patients with untreated celiac disease. Twenty-seven adult patients underwent enteroclysis because of unspecific intestinal symptoms before definitive biopsy proof of celiac disease. Enteroclysis of 123 subjects with similar clinical presentation, including abdominal pain, diarrhea, occult intestinal bleeding, and weight loss, who had a definitive diagnosis other than celiac disease, served as controls. The radiographic features previously described in the literature as indicative of adult celiac disease (i.e., fold thickening, decrease of jejunal folds, increase of ileal folds, small bowel dilatation, flocculation) were evaluated in blinded fashion in all studies and the subjective likelihood of diagnosis of celiac disease was assessed. Assessing every finding separately, each feature proved to have a high specificity (78-100%) but low sensitivity (19-59%) for celiac disease. Reversal of jejunoileal fold pattern was the single best feature (specificity 100%, 95% CI 97-100%; sensitivity 59%, 95% CI 40-78%); however, combination of criteria enables establishment of the diagnosis of celiac disease quite accurately (specificity 100%, 95% CI 98-100%; sensitivity 78%, 95% CI 58-91%). Reversal of jejunoileal fold pattern as a single finding as well as combination at least three of the following features, i.e., fold thickening, decrease of jejunal folds ("colonization"), increase of ileal folds ("jejunization"), dilatation, and flocculation, make enteroclysis an accurate tool for diagnosis of celiac disease in adult patients with suspected intestinal disease.

Adult↗

PubMed1979

Divalent cations cooperatively stabilize close membrane contacts in myelin.

Intact nerve myelin compacts to a dehydrated structure of closely apposed membranes when exposed to isotonic solutions at least 10 mM in calcium or tetracaine. The repeat period of the membrane pair in the compacted structure measured by X-ray diffraction is about 126 A in both central and peripheral mammalian nerve myelins whereas the normal periods are about 158 and 178 A, respectively. The electron density profile of compacted myelin shows an asymmetric membrane unit with thickness similar to that of the symmetric bilayer of flocculated myelin lipids. The centrosymmetrically averaged myelin membrane profile is similar to that of the lipid bilayer except at the surface where residual protein is concentrated. Dispersions of extracted total myelin lipids flocculate under similar conditions to those causing myelin compaction, indicating that similar forces act in both processes. Compaction is always accompanied by lateral segregation of intramembrane particles out of the close-packed domains. Lateral displacement of intramembrane proteins form compacted domains can be driven by the attraction of the lipid surfaces for each other. Rates of compaction vary with compacting reagent, concentration, tissue, and temperature, and probably reflect the permeability of the tissue. Extensive compaction by calcium or tetracaine leads to disruption and vesiculation of the spirally wrapped myelin membranes.

Animals↗

PubMed1993

Studies on host specificity in Paragonimus westermani: ultrastructural study of inflammatory reactions to the parasite in rat muscles.

Inflammatory reactions to the lung fluke, Paragonimus westermani, in an abnormal host, the rat, were studied by electron microscopy. Inflammatory cells accumulated around the worms in rat muscles, but the reaction varied significantly in intensity as well as distribution of inflammatory cells from worm to worm in the same and different hosts. In an accumulation of inflammatory infiltrates around the worm, eosinophils were more commonly seen, and neutrophils and macrophages were fewer in number. Mast cells appeared rarely. Where inflammatory cells touched to the worms, the tegument of the worms was covered with moderately electron-dense flocculent material which included dense granules. This material, which probably consisted of immune complexes of host antibody and antigen secreted from tegumental granules, seemed to block the inflammatory cells from adhering to the worm surfaces. Inflammatory cells made direct contact with worm surfaces where flocculent material was absent. Dense secretory material was discharged from some eosinophils as a result of degranulation.

Animals↗

PubMed1993

Novel affinity separations based on perfluorocarbon emulsions. Development of a perfluorocarbon emulsion reactor for continuous affinity separations and its application in the purification of human serum albumin from blood plasma.

Perfluorocarbon affinity emulsions are generated by the homogenisation of a perfluorocarbon oil with a polymeric fluorosurfactant previously derivatised with an affinity ligand and subsequently cross-linked in situ. This procedure gives rise to a novel liquid affinity adsorbent that can be used for continuous protein purification. Discrete emulsion droplets were found to be unstable when pumped for prolonged periods; however, when flocculated, the emulsion floccules with diameters of around 125 microns, were very stable and sedimented faster. A four-stage reactor unit (perfluorocarbon emulsion reactor for continuous affinity separations, PERCAS) was designed and constructed to carry out continuous separations, and exploited the unusual properties of the absorbent, i.e. liquid nature and high density. Each of the four stages of PERCAS consisted of a mixing tank, for contacting between emulsion phase and aqueous phase, adjacent to a settling tank for the subsequent separation of emulsion from the aqueous phase. Using PERCAS adsorption, washing, elution and re-equilibration of the emulsion could be carried out continuously with emulsion recycle. Using single-component adsorption of human serum albumin to a perfluorocarbon affinity emulsion derivatised with the triazine dye C.I. Reactive Blue 2, PERCAS was optimised with respect to flow-rates and input concentrations. The work was then extended to the continuous purification of essentially homogeneous human serum albumin from blood plasma.

Adsorption↗

PubMed1977

Studies on the in vivo cellular reactions of insects: an ultrastructural analysis of nodule formation in Galleria mellonella.

Cellular aggregates or nodules which formed in Galleria mellonella larvae in response to injections of killed Bacillus cereus were examined during their first 24 hr of development. The initial aggregation stage was very rapid, occurring within 1 min, and was brought about by the release of an adhesive flocculent material by granular haemocytes in contact with the bacteria. This material, which subsequently became increasingly electron dense owing to melanin deposition, consolidated and by 5 min ramified all the intercellular spaces. The granular cells degenerated, releasing portions of cytoplasm form their peripheries, and eventurally appeared in the matrix as voids containing loosely flocculent material. No bacterial breakdown was seen, however. From 2-4 hr, plasmatocytes began to encapsulate the necrotic mass, and by 24 hr a complete sheath, composed of three discrete regions of cells, was formed. These findings are discussed in relation to the various proposed mechanisms of nodule and capsule formation.

Animals↗

PubMed1987

Physico-chemical treatments for the complete removal of non-ionic surfactants from effluents.

Adsorption isotherms for a selection of non-ionic surfactants on activated carbons indicated the effectiveness of the latter in the removal of these pollutants from secondary effluents. The removal efficiencies were found to be improved when the secondary effluent was first flocculated with ferric chloride. This effectively removed some 80% of the non-ionic surfactant in the effluent. Batch adsorption experiments with powdered activated carbon removed 97% of the surfactant at low carbon dosage. A granular carbon with the best adsorption capacity was selected for continuous-flow operation in which non-ionic surfactants, COD and anionic surfactant alkyl benzene sulphonate were monitored. The breakthrough capacity for the non-ionic surfactants was in excess of 6000 bed volumes throughput of flocculated, sand-filtered effluent in a laboratory scale carbon column. Such a procedure is suggested for the complete removal of such pollutants from effluents.

Journal Article↗

PubMed1989

Domains of the SFL1 protein of yeasts are homologous to Myc oncoproteins or yeast heat-shock transcription factor.

We identified a yeast suppressor gene for flocculation (SFL1), which complemented a newly isolated sfl1 mutant. This mutation causes asexual cell aggregation. SFL1 encodes a 767-amino acid protein which has two domains significantly homologous to Myc oncoproteins and the yeast heat shock transcription factor (HSTF). The Myc homologous region in SFL1 overlaps with the conserved region in a series of interesting proteins: MyoD1, Drosophila achaete-scute, twist, daughterless gene products and immunoglobulin enhancer-binding proteins. In addition, the N-terminal region of the SFL1 gene product shows extensive homology to the DNA-binding domain of HSTF. Mutational analysis of SFL1 demonstrates that it is required for normal cell-surface assembly in vegetative growth. We propose that the SFL1 gene product may be a transcription factor which is involved in regulation of the gene(s) related to yeast flocculation.

Amino Acid Sequence↗

PubMed2006

A new pulping process for wheat straw to reduce problems with the discharge of black liquor.

Aqueous ammonia mixed with caustic potash as wheat straw pulping liquor was investigated. The caustic potash did not only reduce the NH3 usage and cooking time, but also provided a potassium source as a fertilizer in the black liquor. Excess NH3 in the black liquor was recovered and reused by batch distillation with a 98% recovery rate of free NH3. The black liquor was further treated for reuse by coagulation under alkaline conditions. The effects of different flocculation conditions, such as the dosage of 10% aluminium polychloride, the dosage of 0.1% polyacrylamide, the reaction temperature and the pH of the black liquor on the flocculating process were studied. The supernatant was recycled as cooking liquor by adding extra NH4OH and KOH. The amount of delignification and the pulp yield for the process remained steady at 82-85% and 48-50%, respectively, when reusing the supernatant four times. The coagulated residues could be further processed as solid fertilizers. This study provided a new pulping process for wheat straw to reduce problems of discharge black liquor.

Chemical Precipitation↗

PubMed2004

Treatment and detoxification of a sanitary landfill leachate.

The leachate from an old sanitary landfill (Gramacho Metropolitan Landfill, Rio de Janeiro) was characterized and submitted to coagulation and flocculation treatment followed by ozonation and ammonia stripping. The performance of the treatment was assessed by monitoring the removal of organic matter (COD and TOC), ammonium nitrogen and metals. Detoxification was assessed by determining acute toxicity, using the following organisms: Vibrio fisheri, Daphnia similis, Artemia salina and Brachydanio rerio. Membrane fractionation was employed to infer the range of molecular masses of the pollutants found in the effluent, as well as the toxicity associated to these fractions. Of the techniques under investigation, coagulation and flocculation followed by ammonia stripping were the most effective for toxicity and ammonium nitrogen removal. Membrane fractionation was effective for COD removal; however, acute toxicity was almost the same in all the fractionated samples. Ozonation was moderately effective for COD removal, but significant toxicity removal was only attained when high ozone doses were used.

Animals↗

PubMed2006

The effect of coagulation on the toxicity and mutagenicity of reclaimed municipal effluents.

The objectives of this work were the assessment of the effectiveness of coagulation on the reclamation of secondary effluents and the evaluation of the quality of reclaimed waters by the examination of their ecotoxic and mutagenic properties. Aluminum coagulants resulted in higher removal of organic content, than iron coagulant, reaching up to 40%; the removal of heavy metals, such as zinc and copper was enhanced by the addition of a low strength anionic flocculant. The toxicity of pre-concentrated samples to the bacteria Vibrio fischerii was related to the heavy metal content, especially zinc and copper, indicating the significance of the metals bioavailability and their potential interactive effects. The secondary effluents exhibited mutagenic effects on strain TA 98; these effects were increased during coagulation with ferric chloride (both in absence and presence of flocculant). However, the addition of aluminum coagulants resulted in a decrease of mutagenic potential of secondary effluents, due to the extended removal of organic matter.

Aliivibrio fischeri↗

PubMed2006

Investigation on the interaction between colloidal gold and human complement factor 4 at different pH by spectral methods.

The interaction between colloidal gold and human complement factor 4 (human C4) at different pH was investigated by spectral methods, including absorption and resonance light-scattering spectrometry. According to the changes of color and absorption spectra of colloidal gold solution in presence of human C4, the interaction between colloidal gold and human C4 was quantitatively investigated using a semi-empirical "flocculation parameter". At the same time, the changes of resonance light-scattering spectra and transmission electron microscopy (TEM) images indicate that the aggregation of colloidal gold happens by electrostatic interaction in presence of human C4 in the pH range 5-6. However, the colloidal gold solution remains stable at pH >6 and pH <5 due to the repulsive electrostatic interaction between colloidal gold and human C4. The flocculation parameter is directly proportional to the concentration of human C4 in the range from 9.7 to 233.0 microgl(-1). In addition, the interactions between the colloidal gold and bovine serum albumin (BSA) as well as human serum albumin (HSA) were also investigated using the same methods. It was found that there was no aggregation of colloidal gold in presence of BSA and HSA in the pH range 5-6. However, when the pH of solution is 4, the aggregation of colloidal gold happens. Because BSA and HSA have different structure, the intensity of aggregation of colloidal gold in presence of BSA is greater than that in presence of HSA at pH 4.

Animals↗

PubMed2005

Polyelectrolyte complex formation and stability when mixing polyanions and polycations in salted media: a model study related to the case of body fluids.

Controlled drug delivery and gene transfection involve contact of artificial polyelectrolytic systems that can interact dramatically with biopolymers and cells when they are introduced in blood. Given the complexity of body aqueous media in terms of physical chemistry, a model approach was selected in attempt to understand the behavior of artificial polyelectrolytes introduced in body fluids. Selection in terms of molecular weight was highlighted in a previous paper. In the present study the formation and the stability of fractions obtained when a polycation is added to a polyanion according to a titrating process mimicking injection into blood was considered for different polycation/polyanion couples. Poly(amino serinate) and poly(L-lysine) were used as polybases, and poly(acrylic acid), poly(L-lysine citramide) and poly(L-lysine citramide imide) as polyacids. Four fractions corresponding to different positive/negative charge ratios were formed for each couple. At low polyion concentration (13 mg/L) and given salt concentration, the stability of the complex fractions depended on molecular weight and charge density of the polyions. The NaCl concentration required to destabilize the different interpolyelectrolyte complexes was found to decrease from the first fraction to the fourth one. Upon decreasing the salt concentration, macroscopic flocculation occurred in the case of PLL/PAA complex fractions only. For the other couples, dynamic light scattering showed that several hundreds nanometer sized particles were formed that were stable in a broad range of NaCl concentration, including the physiological 0.15 ionic strength. At higher polyion concentrations, stable solid precipitate was formed regardless of the system. The absence of flocculation in the case of highly diluted poly(L-lysine citramide) and poly(L-lysine citramide imide) polyanions in salted media is assigned to the presence of non-ionic hydroxyl and amide polar groups along the complexed chains. Data show that introducing non-ionic functions along the polyelectrolyte chains is a good means to keep interpolyelectrolyte complexes dispersed in salted media, a conclusion of interest in the field of condensation of genes by polycations.

Body Fluids↗

PubMed2004

Characterization of fractionated asphaltenes by UV-vis and NMR self-diffusion spectroscopy.

Asphaltenes have been fractionated by liquid/liquid extraction, yielding four subfractions. The characteristics of fractionated asphaltenes were studied with respect to solubility, aromaticity, heteroatom content, and diffusion behavior. It was observed that asphaltenes from the four subfractions showed variations in their tendency to flocculate and also distinct differences in aromaticity. Furthermore, NMR self-diffusion studies showed that the average diffusion coefficients varied for asphaltenes from the different subfractions. The results suggest a variation in average size and stability between asphaltenes, depending on what subfraction they belong to. The subfraction that consisted of asphaltenes with the largest average size and the highest aromaticity was also found to contain the asphaltenes that had the strongest tendency to flocculate.

Journal Article↗

PubMed2004

Effect of floc structure on the rate of shear coagulation.

We derived a mathematical expression for the temporal evolution of the number of particles due to shear coagulation, covering the later stage by expanding the initial stage approximation to take into account the formation of floc structure. In the derivation, it is assumed that flocculation proceeds through binary collisions between identical fractal flocs. The capture efficiency between flocs is calculated on the basis of trajectory analysis, which is determined by viscous hydrodynamic interaction between flocs and van der Waals attractive forces between two primary particles located at colliding points of flocs. The validity of the derived equation was tested by a coagulation experiment using polystyrene sulfate latex particles under conditions of rapid coagulation. The experiment was carried out in a laminar Couette flow generated in the gap between two concentric cylinders. Careful and direct observation of flocculation under microscopy provided the data on the fractal dimension as well as the temporal evolution of number concentration of flocs. The measured rate of coagulation gradually increases in accordance with the formation of the fractal structure of flocs. This behavior agreed very well with the prediction based on the derived equation.

Journal Article↗