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PubMed2005

[Effect of Ginkgo biloba extract on neuronal apoptosis in rabbit with kaolin-induced syringomyelia].

OBJECTIVE: To evaluate the effect of Ginkgo biloba extract (GBE) on neuronal apoptosis in rabbits with kaolin-induced syringomyelia. METHODS: Twenty-four of 30 Chinese white rabbits were subjected to injection of 25% kaolin mixed with equal volume (0.6 ml) of cerebrospinal fluid drawn from the cisterna magna under ketamine anesthesia. Twelve of these 24 rabbits then received intravenous injection of 5 ml of GBE (5 ml/days for 14 days, GBE treatment group) while the other 12 were treated with the same amount of saline administered in similar manner (saline group). The 6 rabbits without kaolin treatment received a sham operation to serve as the control group. At different time points after the operation, the rabbits were killed and the spinal cord samples examined by immunohistochemistry. RESULTS: Histologically, ischemia and edema in the cervical cord of rabbits in GBE treatment group were less severe than those in saline group. TUNEL-positive and bax-positive neurons were less numerous in GBE treatment group than in saline group, and the former group showed more Bcl-2-positive neurons. The number of apoptotic neurons reached the peak level on day 7 after kaolin injection. CONCLUSION: GBE can ameliorate kaolin-induced hydrocephalus in the upper cervical cord and inhibit kaolin-induced neuron apoptosis.

Animals↗
PubMed1987

[Epithelioid cell-node induced by intracisternal injection of kaolin in rats].

We studied the origin of the epithelioid cells (macrophages) observed in the rat brain in response to the intracisternal injection of kaolin. The rats, two days of age, were used. The animals were killed after thirteen weeks following cisternal injection of kaolin. Massive epithelioid cell-nodes with multifocal necrosis were seen in the subarachnoid space of the cerebellum, in the cerebellar parenchyma and in the fourth ventricle. They were also present in the choroid plexus. The papillary epithelioid cell-nodes were observed onto the aqueduct of Sylvius, the third and lateral ventricles. These were associated with the proliferation of the adventitia of the blood vessel in the subependymal white matter. This suggested that the vascular adventitia played a role for a formation of the epithelioid cell-node in this case. The epithelioid cell was negative in silver-stained preparation. This indicated that microglia was not a source of the epithelioid cell. Reticulin fibers were moderately increased in the lesions. The epithelioid cells phagocytized kaolin granules and gave a strong PAS-positive reaction. However, it seemed that the PAS-positive materials were not identical to the kaolin granules. A rich accumulation of apparently extra- and intracellular kaolin deposits stained metachromatically violet with toluidine blue was seen in the necrotic areas. A large number of the degenerated cells containing kaolin deposits was found especially in the marginal zone of the necrotic areas. Granulation tissue with the amount of spindle-form cells and collagen fibers was also observed in the subarachnoid space. The granulation tissue was formed by hyperplasia of fibroblasts following the proliferation of the epithelioid cells and their necrotic processes.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Kaolin-induced writhing in mice, a new model of possible bradykinin-induced pain for assessment of analgesic agents.

Kaolin induced a clear and reproducible writhing reaction when intraperitoneally injected into mice. A simultaneous injection (i.p.) of soybean trypsin inhibitor (SBTI) significantly suppressed the kaolin-induced writhing reaction. This writhing reaction was markedly potentiated by a simultaneous injection (i.p.) of captopril. In an in vitro experiment kaolin caused kinin-release in mouse plasma, possibly through the activation of prekallikrein. This activation of plasma prekallikrein and kinin-release were inhibited in the presence of SBTI. Some non-steroidal anti-inflammatory agents inhibited the kaolin-induced writhing reaction dose-dependently. These results suggest that kaolin-induced writhing reaction may be caused by the released bradykinin through activation of the plasma kallikrein-kinin system. This model is a novel and simple tool for assessment of analgesic agents.

Acetylcholine↗
PubMed2005

American ginseng berry extract and ginsenoside Re attenuate cisplatin-induced kaolin intake in rats.

PURPOSE: Cisplatin, a chemotherapeutic agent, causes significant nausea and vomiting. It is postulated that cisplatin-induced oxidant stress may be responsible for these symptoms. We tested whether pretreatment with American ginseng berry extract (AGBE), an herb with potent antioxidant capacity, and one of its active antioxidant constituents, ginsenoside Re, could counter cisplatin-induced emesis using a rat pica model. METHODS: In rats, exposure to emetic stimuli such as cisplatin causes significant kaolin intake, a phenomenon called pica. We therefore measured cisplatin-induced kaolin intake as an indicator of the emetic response. Rats were pretreated with vehicle, AGBE (dose range 50-150 mg/kg, IP) or ginsenoside Re (2 and 5 mg/kg, IP). Rats were treated with cisplatin (3 mg/kg, IP) 30 min later. Kaolin intake, food intake, and body weight were measured every 24 h for 120 h. Additionally, the free radical scavenging activity of AGBE was measured in vitro using ESR spectroscopy. RESULTS: A significant dose-response relationship was observed between increasing doses of pretreatment with AGBE and reduction in cisplatin-induced pica. Kaolin intake was maximally attenuated by AGBE at a dose of 100 mg/kg. Food intake also improved significantly at this dose (P<0.05). Pretreatment with ginsenoside Re (5 mg/kg) also decreased kaolin intake (P<0.05). In vitro studies demonstrated a concentration-response relationship between AGBE and its ability to scavenge superoxide and hydroxyl radicals. CONCLUSION: Pretreatment with AGBE and its major constituent, Re, attenuated cisplatin-induced pica, and demonstrated potential for the treatment of chemotherapy-induced nausea and vomiting. Significant recovery of food intake further strengthens the conclusion that AGBE may exert an antinausea/antiemetic effect.

Animals↗
PubMed2006

Multifunctional microsized modified kaolin and its application in wastewater treatment.

The multifunctional microsized ZnO-PO(4)(3-)-modified kaolin of average diameter about 500nm with the composition Na(2)O:ZnO:Na(3)PO(4):SiO(2):Al(2)O(3)=2.5-8.5:0.04-0.65:0.8-4.5:1.5-2.5:1 (molar ratio) were firstly synthesized from ZnO, Na(3)PO(4), NaOH and kaolin and characterized by standard techniques, its application in oilfield produced wastewater purification was also studied. It was found that the physical properties of ZnO-PO(4)(3-)-modified kaolin such as specific surface area, porous volume and pore diameter increased independently compared to the starting kaolin. It was also found that the prepared kaolin has multifunctional properties to decrease COD and BOD value, remove scaling ion (Fe(n+), Ca(2+) and Mg(2+)), improve MF, decrease bacteria and inhibit corrosion and can be used effectively in oilfield wastewater purification.

Kaolin↗
PubMed2006

Removal of heavy metals from kaolin using an upward electrokinetic soil remedial (UESR) technology.

An upward electrokinetic soil remedial (UESR) technology was proposed to remove heavy metals from contaminated kaolin. Unlike conventional electrokinetic treatment that uses boreholes or trenches for horizontal migration of heavy metals, the UESR technology, applying vertical non-uniform electric fields, caused upward transportation of heavy metals to the top surface of the treated soil. The effects of current density, treatment duration, cell diameter, and different cathode chamber influent (distilled water or 0.01 M nitric acid) were studied. The removal efficiencies of heavy metals positively correlated to current density and treatment duration. Higher heavy metals removal efficiency was observed for the reactor cell with smaller diameter. A substantial amount of heavy metals was accumulated in the nearest to cathode 2 cm layer of kaolin when distilled water was continuously supplied to the cathode chamber. Heavy metals accumulated in this layer of kaolin can be easily excavated and disposed off. The main part of the removed heavy metals was dissolved in cathode chamber influent and moved away with cathode chamber effluent when 0.01 M nitric acid was used, instead of distilled water. Energy saving treatment by UESR technology with highest metal removal efficiencies was provided by two regimes: (1) by application of 0.01 M nitric acid as cathode chamber influent, cell diameter of 100 mm, duration of 18 days, and constant voltage of 3.5 V (19.7 k Wh/m(3) of kaolin) and (2) by application of 0.01 M nitric acid as cathode chamber influent, cell diameter of 100 cm, duration of 6 days, and constant current density of 0.191 mA/cm(2) (19.1 k Wh/m(3) of kaolin).

Algorithms↗
PubMedDate not supplied

Pharmacological characterization of cyclosporine A-induced kaolin intake in rats.

Kaolin intake behavior of rats is known to be one of the useful animal models to evaluate the emetic and antiemetic actions of drugs. The present study was aimed at elucidating the pharmacological characterization of cyclosporine A (CsA)-induced kaolin intake in rats. Subchronic treatment (once a day for 3 days) with CsA produced a dose- and time-dependent increase in kaolin intake. Scopolamine (muscarinic antagonist), mepyramine (selective histamine H(1) antagonist) and diphenhydramine (H(1) and muscarinic antagonist) but neither domperidone (dopamine D(2) antagonist) nor ondansetron (serotonin 5-HT(3) antagonist) significantly inhibited CsA-induced kaolin intake. These findings suggest that an activation of central muscarinic and H(1) receptor is closely associated with CsA-induced kaolin intake in rats. Use of scopolamine and/or diphenhydramine may be possible regimens to alleviate and avoid nausea and vomiting in patients with CsA therapy.

Animals↗
PubMed2006

Geochemical reconnaissance of heavy metals in kaolin after electrokinetic remediation.

The development or implementation of electrokinetic soil remediation technique requires a good knowledge of how the contaminants are retained within the soil-water system. This paper investigates the speciation and extent of migration of the heavy metals, Cr(VI), Cr(III), Ni(II), and Cd(II), during electrokinetic soil remediation. A geochemical assessment of how the contaminants are held within the kaolin soil under induced electric potential is made by using the equilibrium model MINEQL+. The study is performed for three different contaminant cases: the Cr(VI) existing alone in the soil, the Cr(VI) combined with Ni(II) and Cd(II) in the soil, and the Cr(VI) combined with Ni(II) and Cd(II) in the soil in the presence of a reducing agent (sulfide). The adsorption of the studied metals by kaolin was implemented as an electrostatic behavior. FITEQL 4.0 model was used to determine the equilibrium constants of the electrostatic adsorption model of kaolin for the studied metals by optimizing the experimental titration and adsorption data of kaolin. This study showed that the initial speciation of the contaminants in the soil prior to the electrokinetic treatment depends on the type and amounts of contaminants present as well as on the presence of the co-contaminants or any reducing agent. Moreover, the extent of migration of the contaminants is strongly dependent on their initial speciation prior electrokinetic treatment. This study also showed that adsorption and precipitation are the significant hindering mechanisms for the removal of heavy metals from kaolin soil during electrokinetic treatment. The adsorption and precipitation forms of Cr(III), Ni(II), and Cd(II) increased near the cathode and decreased near the anode, whereas the adsorption form of Cr(VI) increased near the anode as well as in the middle region. However, the precipitation form of Cr(III), Ni(II), and Cd(II) as Cr2O3 or Cr(OH)3, Ni(OH)2, and Cd(OH)2, respectively, dominates over their adsorption form as they get closer to the cathode. Overall this study demonstrates that the electrolysis reactions control contaminant speciation and distribution in the soil during electrokinetic remediation because of the generated variations in pH and redox potential in the soil as a result of these reactions.

Chemical Precipitation↗
PubMed1989

Involvement of prostaglandins in kaolin-induced writhing reaction in mice.

The relationship between the kaolin-induced writhing reaction and production of arachidonate metabolites (PGs) in mice was studied. PGs were released into the peritoneal cavity after intraperitoneal injection (i.p.) of kaolin (2.5 mg/mouse) with a peak at 5 min. About 80% of the total amount was 6-keto-PGF1 alpha. There was a significant correlation (r = 0.8237, p less than 0.001) between the number of writhes and the amount of 6-keto-PGF1 alpha. The writhing reaction induced by kaolin was significantly inhibited by simultaneous injection of soybean trypsin inhibitor (SBTI; 2.5 mg/mouse) and increased by simultaneous injection of captopril (50 micrograms/mouse). The writing reaction induced by kaolin which was inhibited by oral administration of indomethacin (1 mg/kg) was restored by exogenous i.p. injection of PGI2-Na (2-10 ng/mouse). Indomethacin, ibuprofen and alminoprofen inhibited the writhing reaction and reduced the level of peritoneal 6-keto-PGF1 alpha in parallel manner. Tiaramide, pentazocine and morphine inhibited the writhing reaction without reducing the revels of 6-keto-PGF1 alpha. These results differentiate the site of action of these analgesics. They suggest that the mechanism of the kaolin-induced writhing reaction in mice involves a synergic pain caused by simultaneously released bradykinin and PGI2. This model is a useful tool which allows differentiation of mode of action of analgesics by simultaneous determination of the writhing response and peritoneal 6-keto-PGF1 alpha.

6-Ketoprostaglandin F1 alpha↗
PubMedDate not supplied

Distribution behavior of pyrene to adsorbed humic acids on kaolin.

The distribution behavior of pyrene on humic acid (HA)-kaolin complexes, prepared by adsorbing HA on kaolin, was investigated by batch experiments. The distribution coefficient (Kd) of pyrene on the HA-kaolin complex increased with the fraction (f(oc)) of organic carbon adsorbed to the surface of the kaolin. This can be attributed to hydrophobic interactions between pyrene and the adsorbed HAs. The effects of adsorbed HAs were quantitatively evaluated by calculating the distribution coefficient (K(oc)) and affinity constant (K(oc)ads) for pyrene to the adsorbed HAs. A fluorescence quenching method was employed to determine the affinity constant (K(oc)aq) of pyrene to HAs dissolved in an aqueous solution. When the K(oc) values were compared with the K(oc)aq values, the K(oc) values were found to be 4 to 11 times larger than the K(oc)aq values. On the other hand, the K(oc)ads values were 4 to 9 times larger than the K(oc)aq values. These indicate that the affinity for pyrene is enhanced by the adsorption of HAs to kaolin. In addition, the K(oc) values increased with increasing average molecular weights of the HAs. These results demonstrate that HAs, when they are adsorbed to clay minerals, play an important role in the deposition of polycyclic aromatic hydrocarbons (PAHs) in a soil environment.

Adsorption↗
PubMedDate not supplied

The role of kaolin particles in the performance of a carbamate-based biocide for water bacterial control.

The influence of kaolin particles on the activity of Pseudomonas fluorescens and on the efficacy of a carbamate-based biocide was investigated. The results indicated that kaolin particles stimulated the activity of the bacteria for all buffered pH values studied (5, 7, and 9); this effect being more evident for the tests carried out at pH 5 and 9. The presence of the clay in P. fluorescens suspensions decreased the efficiency of disinfection of the carbamate. The results also showed that kaolin was very effective in removing carbamate from the culture media. Therefore, the biocide concentration in the solution decreased, and consequently its availability to the bacteria was reduced. The results could be explained by the interaction between kaolin particles and carbamate and by the changes in the configuration of kaolin aggregates, depending on the pH value.

Adsorption↗
PubMed1976

Evidence that Fitzgerald factor counteracts inhibition by kaolin or ellagic acid of the amidolytic properties of a plasma kallikrein.

Fitzgerald trait, an asymptomatic disorder, is associated with abnormalities of surface-mediated plasma reactions, including coagulation via the intrinsic pathway, augmentation of the clot-promoting properties of factor VII, kaolin-mediated fibrinolysis, kinin generation, and enhancement of vascular permeability by diluted plasma (PF/Dil). These abnormalities can be corrected by Fitzgerald factor, an agent probably identical with high molecular weight kininogen found in normal, but not Fitzgerald-trait plasma. Our preparations of Fitzgerald factor possessed a second property. Amidolysis of alpha-N-benzoyl-L-proline-L-phenylalanine-L-arginine-pnitroanilide by a plasma kallikrein (activated Fletcher factor) was inhibited by kaolin or solutions of ellagic acid. Addition of preparations of Fitzgerald factor to kaolin or to solutions of ellagic acid counteracted their inhibitory properties. The action of these preparations was duplicated by solutions of cytochrome C or IgG, suggesting that these agents may inhibit the negative charges of kaolin or ellagic acid. Fitzgerald factor enhanced amidolysis of both normal and Fitzgerald-trait plasmas exposed to kaolin, effects not duplicated by cytochrome C or IgG. Whether or not the two properties of our preparations of Fitzgerald factor are related to the same agent is not yet certain. The relationship between these observations and the biologic role of Fitzgerald factor remains to be investigated.

Benzopyrans↗
PubMed1992

[Alteration of atrial natriuretic peptide and cyclic GMP in cerebrospinal fluid in canine kaolin-induced hydrocephalus].

CSF and Plasma concentrations of atrial natriuretic peptide (ANP) and cyclic GMP (cGMP), which is regarded as a second messenger of ANP, were measured intermittently during the progress of canine kaolin-induced hydrocephalus. Data were analyzed being divided into three groups, normal, acute (within 2 weeks after intracisternal injection of kaolin suspension) and chronic (from 3 to 4 weeks after injection of kaolin suspension) stages of hydrocephalus. The presence of ventricular dilatation was evaluated by MRI or postmortal dissection. ANP, cGMP in CSF and CSF pressure significantly increased in the acute stage of hydrocephalus. In the chronic stage, ANP in CSF and CSF pressure had no statistical difference with data of the normal stage. Cyclic GMP in CSF kept significantly high value in the chronic stage of hydrocephalus. CSF concentrations of Na, CSF osmolarity, plasma ANP, plasma cGMP, plasma ADH, serum Na and serum osmolarity did not change significantly in the course of hydrocephalus. There was a significant positive correlation between ANP in CSF and CSF pressure. ANP in CSF did not correlate with degree of ventricular dilatation. Cyclic GMP in CSF did not correlate with ANP in CSF, nor with CSF pressure. These data suggest that concentration of ANP in CSF may alter directly or indirectly depending on CSF pressure in kaolin-induced hydrocephalus. And cGMP in CSF was suggested to depend not on ANP in CSF, but on other unknown factors in kaolin-induced hydrocephalus.

Animals↗
PubMed1986

[Characteristics of brain tissue damage in kaolin-induced infantile rat hydrocephalus].

Experimental hydrocephalus was induced by an intracisternal injection of 4% or 40% kaolin suspension in 2 days old Wistar rats. They were examined histologically and microangiographically 2 weeks after the injection of kaolin. Hydrocephalic rats were classified into 2 groups, severe hydrocephalic group A and mild hydrocephalic group B. In group A, a marked enlargement of the entire ventricular system with a thinning of the cerebral mantle was observed. On the other hand, the dilatation of the fourth ventricle was more pronounced compared with the other ventricles in group B. In group A, a spongy appearance of brain tissue was observed in the periventricular white matter accompanied with an intracerebral cavity. In these edematous areas, the lack of carbon black perfusion was apparent indicating an occurrence of microcirculatory disturbances. These microcirculatory disturbances and mechanical compression to the cerebral parenchyma may produce defective brain tissue (intracerebral cavity formation). The ependymal cell walls and subependymal glial cell layers were well preserved in spite of the damaged periventricular white matter. In group A, kaolin was present in the fourth ventricle and Sylvian aqueduct. Subependymal gliosis containing macrophages and newly produced blood vessels were observed in the region between the periventricular brain tissue and kaolin granules. These findings indicate that kaolin may produce changes in the ependymal cell and cerebral parenchyma as well as fibrosis and meningitis in the subarachnoid space.

Animals↗
PubMed1982

Pulmonary kaolin granulomas.

We report a patient with multiple pulmonary kaolin granulomas. The granulomas developed secondary to the use of a liquid kaolin suspension for pleural poudrage to treat recurrent spontaneous pneumothoraces. Presumably the kaolin entered the lung through pleuro-alveolar or pleuro-bronchial openings. Kaolin pneumoconiosis is generally regarded as an inhalational pneumoconiosis. However, on rare occasions kaolin may incite lung damage by the mechanism described above.

Adult↗
PubMed2002

Effects of water deficit stress, shade, weed competition, and kaolin particle film on selected foliar free amino acid accumulations in cotton, Gossypium hirsutum (L.).

Leaves of cotton plants, Gossypium hirsutum L., stressed by water deficit, reduced daylight, and weed competition, or treated with a kaolin wettable powder formulation were analyzed for levels of 17 free amino acids (FAAs) using reversed-phase high-performance liquid chromatography. Water deficit stress resulted in heightened free proline levels (49.9-fold, P < 0.001) that were correlated with diffusive resistance (seconds per centimeter). Five other FAAs increased, and the amounts of total free essential (for insect growth and development) amino acids and total FAAs also increased (P < or = 0.05). Cotton grown in 50% shade accumulated significantly more free arginine than control plants. In a small-plot weed competition assay, four FAAs increased and three FAAs decreased in association with weed competition, but because free proline levels were not altered and free arginine levels increased, other stresses aside from water deficit, possibly including shading by tall weeds, appear to have caused the changes. In a small-plot kaolin particle film assay, five FAAs were lower in cotton foliage sprayed weekly with kaolin. Because free proline was unaffected and free arginine was lower, it is possible that kaolin's reflectivity heightened light reception. The responses of free proline and arginine to the treatments used in these assays demonstrate that types and degrees of some stresses to cotton can be characterized by accumulations of certain FAAs. The study also demonstrates how some FAA levels can indicate degrees of cotton stress resulting from weed competition and from kaolin particle film application. Porometry and leaf water potential measurements assisted in corroborating some findings of the study.

Adaptation, Physiological↗
PubMed2002

Copper speciation and accumulation in the gill microenvironment of carp ( Cyprinus carpio) in the presence of kaolin particles.

Carp were exposed to copper adsorbed on kaolin particles at various concentrations (0-2.4 mg/L), and net accumulation due to elevated adsorbed copper in the surrounding water was observed. Copper speciation in the water and fish gill microenvironment was modeled in the presence and absence of kaolin using a chemical speciation program (MINTEQA2). The adsorption affinity constants of kaolin for copper at various pH values used in the speciation calculations were experimentally determined, and the quantitative relationship between the affinity constant and pH was modeled. Copper accumulations in fish gills exposed to kaolin-adsorbed copper was then observed. The results indicate that desorption occurred in the fish gill microenvironment due to both mucus competition of copper and slight increase in water pH. Furthermore, the available copper species increased as a result of desorption, causing a net accumulation of Cu by the gills.

Adsorption↗
PubMed1999

Kaolin-induced hydrocephalus in the hamster: temporal sequence of changes in intracranial pressure, ventriculomegaly and whole-brain specific gravity.

The development of kaolin-induced hydrocephalus in adult hamsters was monitored by measuring changes in intracranial pressure (ICP), ventriculomegaly (VG) and whole-brain specific gravity (SG). Controls were intact or sham operated animals. Relative to controls, ICP of experimental animals increased at 24 h post intracisternal kaolin injection (by approximately 7-fold), reached a maximum on day 6 (by approximately 12-fold) and remained markedly elevated through day 15 (by approximately 5-fold). Ventricles differed in time of onset of distension (third: day 1, lateral: day 2, fourth: day 4) and in time of maximum ventriculomegaly (fourth: day 6; third: day 7; and lateral: day 9). Ventricular distension resulted in alterations in the ependyma; cilia were lost and apical cell surfaces were distorted. The ependyma was ruptured and the subjacent neuropil was exposed to the cerebrospinal fluid in some regions. Whole-brain SG remained constant in controls but declined in hydrocephalic hamsters after day 3 post-kaolin injection and reached its nadir on day 9 when whole-brain water content was 18% greater than in controls. Consistent with the fact that causal relationships exist between increased ICP, ventricular distension and brain edema, the alterations in each parameter occurred sequentially rather than simultaneously, and the time-course of each manifestation of hydrocephalus differed. The data suggest that the pathophysiology of kaolin-induced hydrocephalus in the hamster is tri-phasic: an initial period of rapid change, a brief interval of maximum alteration, and a subsequent period of compensation.

Age Factors↗