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At least 199 records · Page 11Linked to original sources
PubMed2006

Catalytic decolorization of azo-stuff with electro-coagulation method assisted by cobalt phosphomolybdate modified kaolin.

The new catalytic decoloration of C.I. Acid Red 3R with electro-coagulation (EC) method assisted by cobalt phosphomolybdate modified kaolin has been studied. The result showed that this process could effectively remove the C.I. Acid Red 3R contained in wastewater and its color removal efficiency could reach up to 98.3% in 7 min. The kinetics of the catalytic decolorization of Acid Red 3R was also studied. The decolorization reaction order was dependent on the initial concentration [R](0) with respect to the concentration of C.I. Acid Red 3R. At lower [R](0) the order was first, which then decreases with increasing [R](0). The operating parameters such as initial pH, current density and temperature were also investigated. A possible reaction mechanism was proposed.

Catalysis↗
PubMed1998

Monoamine neurotransmitters and amino acids in the cerebrum and striatum of immature rats with kaolin-induced hydrocephalus.

Hydrocephalus is characterized by enlargement of the cerebral ventricles. The behavioral disturbances are, in some cases, rapidly reversible by surgical treatment suggesting that there may be a functional impairment of neurons. Hydrocephalus was induced in 3-week old rats by kaolin injection into the cisterna magna. Parietal cerebrum and striatum content of monoamine neurotransmitters and amino acids were assayed by high performance liquid chromatography (HPLC), 1, 2, or 4 weeks after induction of hydrocephalus. The ventricles exhibited progressive enlargement which was partially reversed by surgical treatment. Cerebral water content was increased at all stages. Increased levels of cerebral aspartate and glutamate suggest that there is the potential for excitatory neurotoxicity. The increase in cerebral taurine correlated negatively with the increase in water content. Cerebral concentrations of norepinephrine and serotonin, and its metabolite 5-HIAA, were increased at 1 and 2 weeks suggesting an increase in their turnover during the early stages of ventricular dilatation. Dopamine and its metabolite DOPAC were transiently diminished in the striatum at 1 and 2 weeks, respectively, suggesting that axonal projections from the brainstem may be impaired. We conclude that the effect of hydrocephalus on amino acids and monoamines varies regionally. Due to increased water content, there may be dilution effects in whole tissue, therefore, it is important to make determinations on the basis of protein content.

Amino Acids↗
PubMed1983

Correction of congenital hydrocephalus in utero I. The model: intracisternal kaolin produces hydrocephalus in fetal lambs and rhesus monkeys.

In the fetus with congenital hydrocephalus, obstruction to the flow of cerebrospinal fluid (CSF) results in ventricular dilation and neurologic impairment. Decompression of the obstructed ventricles before birth may ameliorate the damage and allow normal development to proceed. Although appealing, this pathophysiologic rationale has not been adequately tested because a satisfactory fetal model has not been available. We have developed a model of obstructive hydrocephalus in the fetal lamb and rhesus monkey by injecting kaolin into the cisterna magna through the posterior atlanto-occipital membrane early in the last trimester. Preliminary studies injecting silicone oil were unsuccessful. The development of fetal ventriculomegaly was followed using prenatal ultrasonography. Massive hydrocephalus developed in six sheep, three liveborn at term and three stillborn after premature vaginal delivery, and in 2 fetal rhesus monkeys. All treated animals had external signs of hydrocephalus with marked cranial enlargement. Neuropathologic examinations demonstrated fibrosis of the leptomeninges and subarachnoid spaces around the fourth ventricle. Dilation of the lateral and third ventricles resulted, with attenuation of the cerebral white matter. On histologic examination, the grey matter was relatively well preserved, while the white matter was severely attenuated. This model mimics the clinical and pathologic picture seen in human infants and should allow us to study the pathophysiology of congenital obstructive hydrocephalus and the efficacy and feasibility of its correction in utero.

Animals↗
PubMed2001

As compared to kaolin clotting time, silica clotting time is a specific and sensitive automated method for detecting lupus anticoagulant.

Lupus anticoagulants (LAs) are antiphospholipid antibodies capable of interfering with the coagulation system and modifying in vitro the phospholipid-dependent clotting tests. Colloidal silica was used as activator to perform an activated partial thromboplastin time (aPTT) in 73 plasma samples with pathologically elevated kaolin clotting time (KCT) values using a photooptical automated coagulometer. Samples were incubated for 5 min with micronized silica, and after recalcification, the clotting times were measured. Pathologically prolonged results were confirmed by a confirmation and a neutralization test adding platelet-poor normal plasma (PPNP) and natural phospholipids, respectively. Silica clotting time (SCT) was abnormally elevated in 72/73 (98.6%) (mean ratio 1.71 +/- 0.28) KCT positive samples and normalized (mean ratio 1.03 +/- 0.16) after adding natural phospholipids to test plasma. The values expressed as SCT and KCT ratios were significantly correlated (r = .92; P < .001). SCT was normal in 40 healthy subjects utilised as controls (mean ratio 0.99 +/- 12). Sensitivity, specificity and diagnostic accuracy of SCT were 98.6%, 100% and 97.6%, respectively. Our data suggest that SCT is a sensitive test for detecting LA with a prolonged KCT in automated photooptical coagulometers. This peculiarity makes it particularly useful, in combination with diluted Russel viper venom time (dRVVT), for large-scale screening tests on LA.

Adult↗
PubMed2002

Effect of humic substances on Cu(II) solubility in kaolin-sand soil.

The type and amount of organic matter present in industrially contaminated soils will influence the risk they pose. Previous studies have shown the importance of humic and fulvic acids (FAs) (important components of soil organic matter) in increasing the solubility of toxic metals but were not carried out using toxic metal levels and the pH range typical of industrially contaminated soils. This study investigated the influence of three humic substances (HSs: humates, fulvates and humins) on the solubility of copper(II) ions in kaolinitic soil spiked with Cu at levels representative of industrially contaminated soil. Humates, fulvates and humin were extracted from Irish moss peat, and controlled pH batch leaching tests were conducted on an artificial kaolin-sand soil that was spiked with each. Further leaching tests were conducted on soil spiked with each HS and copper nitrate. Dissolved organic contents were determined by titration and total and free aqueous copper concentrations in the leachate were measured using AAS and ion selective electrode (ISE) potentiometry respectively (dissolved complexed copper levels were determined by difference). It was found that humates and fulvates are partially sorbed by the soil, probably by chemisorption on positively charged gibbsite (Al-hydroxide) sites in the kaolinite. The addition of 340 mg/kg Cu(II) ions did not significantly affect the amount of humate or fulvate sorbed. Dissolved humates and fulvates form soluble complexes with copper over the pH range 3-11. However, in the presence of kaolinite, soluble copper humates and fulvates are unable to compete with the kaolinite for Cu ions at pH 6-7. Above pH 8, humate and fulvate complexes are the only forms of dissolved Cu. Humin is largely insoluble and has little effect on Cu mobility between pH 2 and 12. The implication of this study is that measurement of total soil organic content and water leaching tests should be a standard part of contaminated site investigation.

Adsorption↗
PubMed1998

Treatment with either high or low frequency TENS reduces the secondary hyperalgesia observed after injection of kaolin and carrageenan into the knee joint.

For years, physical therapists have been utilizing a variety of modalities, including transcutaneous electrical nerve stimulation (TENS), in an attempt to manage pain associated with inflammation. However, the data on clinical effectiveness is conflicting and the neurophysiological mechanism of action is not known. The purpose of this study was to investigate the effects of high and low frequency TENS on the secondary hyperalgesia that occurs after joint inflammation. Secondary hyperalgesia is thought to reflect changes in central neurons and is thus a measure of activity of central neurons. This study utilized the kaolin and carrageenan model of knee joint inflammation and measured the effects of TENS treatment on paw withdrawal latency to radiant heat (secondary hyperalgesia), spontaneous pain behaviors and joint circumference. Either high (100 Hz) or low (4 Hz) frequency TENS was applied to the knee joint for 20 min after the development of hyperalgesia. Both high and low frequency TENS resulted in a reversal of the hyperalgesia immediately following treatment. The effects of high frequency TENS lasted through at least 24 h while those of low frequency TENS lasted through 12 h. There was no effect of TENS on spontaneous pain behaviors or joint swelling when compared to controls. Thus, TENS appears to be more effective in reducing referred pain (or secondary hyperalgesia) without affecting guarding or splinting of the affected limb. Thus, clinically, the choice to use TENS may depend on patient symptoms; specifically TENS should be effective in reducing referred or radiating pain.

Animals↗
PubMed2006

Removal of phenol from contaminated kaolin using electrokinetically enhanced in situ chemical oxidation.

The application of electrokinetic treatment to phenol contaminated soil combined with the addition of a chemical oxidant (permanganate) to the catholyte has been evaluated. It was found that the counter-current flow of the phenol (by electrosmosis) and permanganate (by electromigration) leads to a rapid oxidation of the phenol in the soil. After 5 days of treatment over 90% of the phenol (initial concentration 1 g kg(-1) dry soil) in a 15 cm long container of kaolin was removed by electrokinetic treatment with a voltage gradient of 1 V cm(-1) and an initial concentration of KMnO4 of 9 g L(-1) in the catholyte. This level of treatment was achieved with an electrical energy consumption of less than 15 kWh per m3 of soil treated.

Electrochemistry↗
PubMed2006

Accelerated progression of kaolin-induced hydrocephalus in aquaporin-4-deficient mice.

Hydrocephalus is caused by an imbalance in cerebrospinal fluid (CSF) production and absorption, resulting in excess ventricular fluid accumulation and neurologic impairment. Current therapy for hydrocephalus involves surgical diversion of excess ventricular fluid. The water-transporting protein aquaporin-4 (AQP4) is expressed at the brain-CSF and blood-brain barriers. Here, we provide evidence for AQP4-facilitated CSF absorption in hydrocephalus by a transparenchymal pathway into the cerebral vasculature. A mouse model of obstructive hydrocephalus was created by injecting kaolin (2.5 mg/mouse) into the cisterna magna. Intracranial pressure (ICP) was approximately 5 mm Hg and ventricular size <0.3 mm(3) in control mice. Lateral ventricle volume increased to 3.7+/-0.5 and 5.1+/-0.5 mm(3) in AQP4 null mice at 3 and 5 days after injection, respectively, significantly greater than 2.6+/-0.3 and 3.5+/-0.5 mm(3) in wildtype mice (P<0.005). The corresponding ICP was 22+/-2 mm Hg at 3 days in AQP4 null mice, significantly greater than 14+/-1 mm Hg in wildtype mice (P<0.005). Brain parenchymal water content increased by 2% to 3% by 3 days, corresponding to approximately 50 muL of fluid, indicating backflow of CSF from the ventricle into the parenchymal extracellular space. A multi-compartment model of hydrocephalus based on experimental data from wildtype mice accurately reproduced the greater severity of hydrocephalus in AQP4 null mice, and predicted a much reduced severity if AQP4 expression/function were increased. Our results indicate a significant role for AQP4-mediated transparenchymal CSF absorption in hydrocephalus and provide a rational basis for evaluation of AQP4 induction as a nonsurgical therapy for hydrocephalus.

Animals↗
PubMed1984

Regulation of food intake by brown Leghorn cockerels in response to dietary dilution with kaolin.

The ability of adult Brown Leghorn cockerels to regulate food intake precisely was tested by measuring their responses to dietary dilutions with 100, 200, 300 and 400 g kaolin per kg diet. When changed from their original undiluted mash diet, cockerels continued gaining body weight with 100 and 200 g kaolin/kg dilutions, maintained weight with 300 g/kg and lost weight continuously with 400 g/kg. With all dilutions, the birds eventually adjusted weights of dry matter digested per day to the same levels as with the original basal diet. This took a few days with 100 g kaolin/kg, a week or more with 200 and 300 g/kg, and about three weeks with 400 g/kg. They achieved this mainly by increasing consumption of diluted food to maintain their original intake of basal diet. With 400 g kaolin/kg they were unable to compensate fully in amount eaten, but digestibility of the basal diet increased significantly. It is suggested that, given the right conditions, fowls may be able to compensate accurately when challenged with a range of dietary dilutions, the upper limit depending on the density of filler used.

Animals↗
PubMed2006

Brain amyloid accumulates in aged rats with kaolin-induced hydrocephalus.

Amyloid beta-peptide (Abeta) accumulation in aged Sprague-Dawley rats (12 months) with kaolin-induced hydrocephalus was investigated by Abeta(1-40) and Abeta(1-42) immunohistochemistry at 2, 6 and 10 weeks after induction. The low-density lipoprotein receptor-related protein-1 transporting Abeta across the blood-brain barrier was assayed. Age-matched controls showed some positive Abeta staining, mainly in the choroid plexus. At 2 weeks after induction, Abeta staining of the arachnoid and subependymal layer was observed. At 6 weeks, larger Abeta accumulations were prominent at the endothelial and perivascular sites. Intraparenchymal Abeta positively stained accumulations occurred at 10 weeks. Microvessel lipoprotein receptor-related protein-1 staining was progressively reduced from 2 to 10 weeks. The pattern of Abeta deposition and lipoprotein receptor-related protein-1 loss suggests reduced Abeta clearance in chronic hydrocephalus.

Aging↗
PubMed1997

Myelination delay in the cerebral white matter of immature rats with kaolin-induced hydrocephalus is reversible.

We hypothesized that hydrocephalus in young animals could cause a delay in myelination. Hydrocephalus was induced in 3-week-old rats by injecting kaolin into the cisterna magna. Ventricular size was assessed by magnetic resonance imaging. After 1 to 4 weeks, rats were either sacrificed, or treated by diversionary shunting of cerebrospinal fluid and then sacrificed 3 to 4 weeks later. Samples of corpus callosum/supraventricular white matter, fimbria, medulla, and spinal cord were assayed for myelin-related enzyme activities including p-nitrophenylphosphorylcholine phosphocholine phosphodiesterase (PNPCP), glycerophosphocholine phosphocholine phosphodiesterase (GPCP), and 2',3'-cyclic neucleotide 3'-phosphodiesterase (CNPase), and the oligodendrocyte enzyme UDP-galactose, ceramide galactosyltransferase (CGa1T). Myelin basic protein (MBP) and proteolipid protein (PLP) were assayed in cerebrum by immunoblots and Northern blot. The corpus callosum was processed for electron microscopy and myelin thickness to axon diameter ratios were quantified. One week after induction of hydrocephalus, CGa1T and GPCP activity were reduced in the corpus callosum there was less MBP and PLP in the cerebrum, and myelin sheaths around axons greater than 0.4 micron in diameter were abnormally thin. With persistent hydrocephalus, the corpus callosum became thinned, axons were lost, and myelin-related enzyme activities and proteins were decreased. Treatment of hydrocephalus at 1 week largely prevented the damage while shunting at 4 weeks failed to restore the injured white matter. Early reduction in CGa1T activity in the medulla and spinal cord suggest that oligodendrocyte production of myelin was reduced, even before irreversible damage occurred in the corticospinal tracts. We conclude that hydrocephalus in the immature rat brain delays myelination, but compensatory myelination is possible if treatment is instituted prior to the development of axonal injury. Possible mechanisms of oligodendrocyte impairment are discussed.

Animals↗
PubMed2002

Sodium channel-blocking agents are not of benefit to rats with kaolin-induced hydrocephalus.

OBJECTIVE: Hydrocephalus causes damage to periventricular white matter at least in part through chronic ischemia. The sodium channel-blocking agents mexiletine and riluzole have been shown to be of some protective value in various models of neurological injury. We hypothesized that these agents would ameliorate the effects of experimental childhood-onset hydrocephalus. METHODS: Hydrocephalus was induced in 4-week-old rats by injection of kaolin into the cisterna magna. Tests of cognitive and motor function were performed on a weekly basis. In a blinded and randomized manner, mexiletine (0.7, 7, or 42 mg/kg/d) or riluzole (1.4 or 13.6 mg/kg/d) was administered by osmotic minipump for 2 weeks, beginning 2 weeks after induction of hydrocephalus. The brains were then subjected to histopathological and biochemical analyses. RESULTS: Compared with untreated hydrocephalic rats, neither mexiletine nor riluzole was associated with a protective effect on behavioral, structural, or biochemical abnormalities. CONCLUSION: Protection of hydrocephalic brains through pharmacological sodium channel blockade is probably an approach not worth pursuing.

Animals↗
PubMed2002

Thermomonas haemolytica gen. nov., sp. nov., a gamma-proteobacterium from kaolin slurry.

Four aerobic, gram-negative bacterial strains isolated from kaolin slurry used in the production of paper were subjected to a polyphasic analysis and characterization to determine their taxonomic position. Analysis of the 16S rDNA sequences of the four strains revealed that they represent a new lineage within the gamma-Proteobacteria, related to the genera Xanthomonas, Pseudoxanthomonas, Stenotrophomonas, Luteimonas, Xylella and Rhodanobacter. Analysis of the quinone system, the polyamines, the fatty acids and the polar lipids revealed a combination of characteristics that is unique and not described for the phylogenetic relatives. The four strains contain a ubiquinone Q-8, spermidine as the major polyamine, diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine as the predominant polar lipids, and a fatty acid profile with predominantly iso-branched fatty acids. The G+C content of the genomic DNA was determined to be within the narrow range 67.1-68.7 mol%. Determination of DNA relatedness, as well as riboprint band patterns and amplified fragment length polymorphism profiles, clearly demonstrated that the four strains are members of a single species. Antibiotic-susceptibility patterns were identical for the four strains. Although showing a high degree of similarites in physiological and biochemical patterns, each of the four strains could be distinguished from the others on the basis of a few biochemical characteristics. On the basis of the estimates of phylogenetic relationships derived from the 16S rDNA sequence analyses, the observed chemotaxonomic characteristics and other phenotypic traits, a new genus, Thermomonas gen. nov., and species, Thermomonas haemolytica sp. nov., are proposed for the strains A50-7-3T (= DSM 13605T = LMG 19653T), B 50-7-1 (= DSM 13598 = LMG 19655), D50-7-1 (= DSM 13610 = LMG 19656) and B50-8-1 (= DSM 13599 = LMG 19654), with strain A50-7-3T as the type strain.

Base Composition↗
PubMed1976

A standardized bioassay for platelet factor 3 released by kaolin.

The test for platelet factor 3 described by Hardisty & Hutton (1975) has been modified to conform to the usual design for a parallel-line bioassay. Manchester Comparative Thromboplastin has been used as assay Standard, allowing an arbitrary unit of activity to be adopted. However, experiments suggested that the platelet activity measured was different from tissue factor activity. Platelets are tested as platelet-rich plasma diluted in a standardized mixture of plasma and fibrinogen, so that differences between the clotting factors of the test samples are eliminated, as verified by experiments on haemophiliacs and patients on anticoagulant treatment. Sonication and repeated freezing and thawing of platelet-rich plasma showed that approximately 15% of the PF3 is released by kaolin. In vivo, a single dose of 600 mg of aspirin reduced the PR3-release to half the previous value in 2 h; initial values were regained in 5-8 days.

Anticoagulants↗
PubMed2006

Effects of heparin, haemodilution and aprotinin on kaolin-based activated clotting time: in vitro comparison of two different point of care devices.

BACKGROUND: During cardiopulmonary bypass (CPB), measurement of kaolin-based activated clotting time (kACT) is a standard practice in monitoring heparin-induced anticoagulation. Despite the fact that the kACT test from the Sonoclot Analyzer (SkACT) has been commercially available for several years, no published data on the performance of SkACT are available. Thus, the aim of this in vitro study was to compare SkACT with an established kACT from Hemochron (HkACT). METHODS: Blood was withdrawn from 25 patients before elective cardiac surgery. SkACT and HkACT were measured in duplicate after in vitro administration of heparin (0, 1, 2 and 3 U/ml), calcium-free lactated Ringer's solution (25% and 50% haemodilution) and aprotinin (200 kIU/ml). RESULTS: A total of 600 duplicate kACT measurements were obtained from 25 cardiac surgery patients. Overall, mean bias +/- SD between SkACT and HkACT was 7 +/- 70 s (1.3% +/- 14.1%). Administration of heparin, haemodilution and aprotinin induced a comparable effect on both activated clotting time (ACT) tests. Mean bias ranged from -4 +/- 39 s (-1.7% +/- 12.9%) to 4 +/- 78 s (3.2% +/- 15.6%) for heparinzed blood samples after haemodilution or aprotinin application and increased after combined aprotinin administration and haemodilution. After haemodilution and administration of aprotinin, both ACT tests were less reliable for values >480 s in heparinized blood samples. CONCLUSION: Accuracy and performance of SkACT and HkACT were comparable after in vitro administration of heparin, aprotinin and haemodilution. Both ACT tests were considerably affected by aprotinin and haemodilution.

Anticoagulants↗
PubMed2003

Tacrolimus and cyclosporine A are of no benefit to young rats with kaolin-induced hydrocephalus.

Hydrocephalus causes damage to periventricular axons. Tacrolimus, cyclosporine A (CsA) and calpain inhibitors have been shown to protect axons in rat models of acute traumatic brain injury. We hypothesized that these agents would ameliorate the axon damage and behavioral effects in experimental hydrocephalus. Hydrocephalus was induced in 3-week-old rats by injection of kaolin into the cisterna magna. Tests of cognitive and motor function were performed on a weekly basis. In a blinded and randomized manner, tacrolimus (FK506; 3.6 mg/kg body weight) or CsA (10 mg/kg) was administered once daily by subcutaneous injection for 2 weeks, beginning 2 weeks after induction of hydrocephalus. In a separate experiment, calpain inhibitor I (10 mg/kg/day) was administered by continuous subcutaneous infusion. The brains were subjected to histopathological and biochemical analyses after 2 weeks of treatment. There was no statistically significant protection in regard to behavior, brain structure or brain composition in any of the experiments. However, there was biochemical and histological evidence of renal injury following chronic tacrolimus and CsA administration. Calcineurin inhibition does not offer significant protection in this rat model of hydrocephalus.

Animals↗