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At least 1,783 records · Page 99Linked to original sources
PubMed2001

Calcite precipitation induced by polyurethane-immobilized Bacillus pasteurii.

Polyurethane (PU) foam was used to immobilize the whole cell of Bacillus pasteurii. The immobilized cells exhibited the rates of calcite precipitation and ammonia production as high as those of the free cells. Scanning electron micrographs identified the cells embedded in calcite crystals throughout PU matrices. Calcite in PU showed little effect on the elastic modulus and tensile strength of the polymer, but increased the compressive strengths of concrete cubes, whose cracks were remediated with PU-immobilized cells. These observations led us to believe that the calcite might remain as a form of precipitation, not as a bonding material within the matrices.

Journal Article↗
PubMed2001

Fabrication of hydroxyapatite bodies by uniaxial pressing from a precipitated powder.

Hydroxyapatite (OHAp) has been obtained by using a precipitation method. Thermal stability of the precipitated powder has been checked to define an appropriate working range to process ceramic bodies without the appearance of odd phases. Pellets of hydroxyapatite have been manufactured by means of uniaxial pressing and convenient thermal treatments have been investigated to achieve high density OHAp bodies. Finally, factors that could affect the ultimate mechanical properties of the sintered bodies prepared by uniaxial pressing have been discussed.

Hydroxyapatites↗
PubMed2001

Human immunodeficiency virus-positive patients with posterior intracorneal precipitates.

PURPOSE: To describe an unusual and possibly new keratopathy in human immunodeficiency virus (HIV)-positive patients. DESIGN: Retrospective observational case series. PARTICIPANTS: : Six HIV-positive patients at four centers. METHODS: A complete medical history was obtained and a thorough ophthalmic examination was performed on each of the patients. RESULTS: Each patient had bilaterally symmetrical keratopathy consisting of variably pigmented round and reticular posterior intracorneal precipitates at the level of Descemet's membrane. The precipitates were diffuse, but larger and more prominent near the limbus and finer toward the central cornea. None of the eyes were inflamed, and all had normal vision. No patient had uveitis on presentation or any history of cytomegalovirus retinitis. CONCLUSION: These patients have a unique posterior keratopathy, which requires further investigation.

Adult↗
PubMed2001

L-NAME precipitates catatonia during ethanol withdrawal in rats.

The effect of N(G)-nitro-L-arginine methyl ester (L-NAME), a non-specific inhibitor of nitric oxide (NO) synthase, on catatonia in ethanol dependent rats was investigated. Ethanol was given to rats by a modified liquid diet. An isocaloric liquid diet without ethanol was also given to control rats. L-NAME (50, 100 and 200 mg/kg) and saline were injected intraperitoneally to ethanol-dependent rats 30 min before ethanol withdrawal. Then, catatonia was evaluated by vertical wire test at the 30th min, 2nd, 4th and 6th h of ethanol withdrawal. The injections were repeated 30 min before the observation of 6 h. Locomotor activity was also recorded for 5 min in the same observation intervals. L-NAME (200 mg/kg) or saline were also injected to ethanol non-dependent control rats. L-NAME (50 and 100 mg/kg) inhibited both incidence and intensity of the audiogenic seizures which appeared at 6 h of ethanol withdrawal. L-NAME (200 mg/kg) produced a significant augmentation in both incidence and intensity of the catatonia in ethanol dependent rats. This dose of L-NAME also reduced the locomotor activity of both ethanol dependent and non-dependent rats. The locomotor inhibitory effect was more prominent in ethanol-dependent group. The catatonia precipitating effect of L-NAME was not prevented by L-arginine (1 g/kg, i.p.), a NO precursor, pretreatment. In the naive rats, L-NAME also did not produce catatonia. These results indicate that L-NAME has a catatonia precipitating effect during ethanol withdrawal in rats and this effect seems to be independent from NO mediated mechanisms.

Acoustic Stimulation↗
PubMed2003

Microarray analysis of genes expressed in the frontal cortex of rats chronically treated with morphine and after naloxone precipitated withdrawal.

Opioid dependence may be associated with adaptive changes in gene expression in the brain. In the present study we used DNA microarrays (U34A; Affymetrix) to analyze the expression of about 8000 genes in the frontal cortex of rats chronically treated with morphine and in rats after naloxone precipitated withdrawal. Chronic treatment for 10 days with ascending doses of morphine (10-50 mg/kg twice daily) resulted in a more than twofold induction of 14 genes after the last injection of morphine. The majority of these genes code for heat shock proteins (hsp70, hsp 27, hsp 40, hsp105, GRP78, etc.). The expression of the heat shock genes in the morphine-treated animals was reversed by naloxone (10 mg/kg). The opioid antagonist, in turn, precipitated withdrawal and increased the expression of a set of genes which are predominantly transcription factors (krox20, CREM, NGFI-B, IkappaB, etc). Only a few genes remained increased after naloxone application. Such persistently changed genes code for arc, a cytoskeleton-associated protein which is induced by synaptic activity, ania-3, a splice variant of the Homer 1 protein which is critically involved in activity-dependent alterations of synaptic function and rPer2, a protein regulating circadian rhythms. For selected genes the changes in gene expression were confirmed by real time PCR and by in situ hybridization. These findings indicate that the persistent changes in long-lasting plasticity during opiate dependence do not primarily depend on the increased expression levels of genes encoding for neurotransmitter, receptor and/or ion channel proteins, but rather on altered pattern of synaptic connectivity.

Animals↗
PubMed2001

The seasonal changes in the concentration of polycyclic aromatic hydrocarbons in precipitation and aerosol near Lake Balaton, Hungary.

The concentration of polycyclic aromatic hydrocarbons (PAHs) in atmospheric precipitation and aerosol samples was monitored in a rural site by Lake Balaton, Hungary to examine the seasonal variation. The seasonal mean concentration of individual 3-6-ring PAHs in precipitation varied from 1 to 54 ng l-1 and from 3 to 350 ng l-1 in summer and winter, respectively. In the atmospheric aerosol samples the seasonal mean concentration of PAHs varied from 4 to 880 pg m-3, from 4 to 300 pg m-3, from 11 to 1050 pg m-3 and from 36 to 5000 pg m-3 in spring, summer, autumn and winter, respectively. Wet (412 micrograms m-2 year-1) and aerosol (190-300 micrograms m2 year-1) deposition rates were also estimated indicating that the two processes are of comparable importance in the removal of 3-6-ring PAHs from the atmosphere.

Aerosols↗
PubMed2002

Time series study of concentrations of SO4(2-) and H+ in precipitation and soil waters in Norway.

Along with a steady reduction of acid inputs during 14 years of intensive forest monitoring in Norway, the influence of acid deposition upon soil water acidity is gradually reduced in favour of other and internal sources of H+ and sulphate, in particular from processes in the upper soil layer. We used statistical analyses in two steps for precipitation, throughfall and soil water at 5, 15 and 40 cm depths. Firstly, we employed time series analyses to model the temporal variation as a long-term linear trend and a monthly variation, and by this filtered out residual, weekly variation. Secondly, we used the parameter estimates and the residuals from this to show that the long term, the monthly and the weekly variation in one layer were correlated to similar temporal variation in the above, adjacent layer. This was strongly evident for throughfall correlated to precipitation, but much weaker for soil water. Continued acidification in soil water on many plots suggests that the combined effects of anthropogenic and natural acid inputs exceed in places the buffering capacity of the soil.

Acid Rain↗
PubMed1999

Interactions between precipitation and Scots pine canopies along a heavy-metal pollution gradient.

Bulk precipitation and stand throughfall were collected during 1992-96 at distances of 0.5, 4 and 8 km from the Harjavalta Cu-Ni smelter, southwestern Finland. The amounts of heavy metals (Cu, Ni, Zn, Fe) and mineral nutrients in bulk precipitation and throughfall were highest at 0.5 km. Although the canopy coverage was low at 0.5 km, the amounts of heavy metals intercepted by the canopy were extremely high. The proportion of foliar leaching relative to the wash-off of dry deposition from the needle surfaces decreased on moving towards the smelter for all elements, except for K. The high rate of K leaching from the needle tissues close to the smelter demonstrated that the K throughfall flux has been greatly altered by the heavy pollution load.

Journal Article↗
PubMed1999

Calciphylaxis precipitated by ultraviolet light in a patient with end-stage renal disease secondary to systemic lupus erythematosus.

Calciphylaxis is a rare and severe calcification syndrome described mainly in patients with end-stage renal disease (ESRD) undergoing dialysis or with a renal transplant. This life-threatening condition is characterized by the abrupt onset of painful ischemic skin ulcers and necrosis. Secondary local and systemic infection may supervene and, without timely and appropriate interventions, calciphylaxis may be fatal. A precipitant or challenging agent is believed to be necessary to initiate the process. We describe a case of a woman with ESRD receiving continuous ambulatory peritoneal dialysis who developed calciphylaxis in the setting of severe hyperparathyroidism after receiving UV photoradiation therapy. We suggest that the UV light served as the challenging agent in the precipitation of this devastating condition.

Adult↗
PubMed2002

Naloxone-precipitated withdrawal jumping in 11 inbred mouse strains: evidence for common genetic mechanisms in acute and chronic morphine physical dependence.

Physical dependence is a widely known consequence of morphine intake. Although commonly associated with prolonged or repeated morphine administration, withdrawal symptoms can be elicited even after a single prior morphine exposure. What remains contentious is the extent to which physical dependence following acute and chronic morphine treatment is mediated by common physiological substrates and, accordingly, represent distinct syndromes. The genetic relationship between acute and chronic morphine dependence was thus presently studied by comparing mice of 11 inbred strains (129P3, A, AKR, BALB/c, C3H/He, C57BL/6, CBA, DBA/2, LP, SJL, and SWR) for naloxone-precipitated withdrawal jumping responses using three subcutaneous morphine administration paradigms: acute (single injection) or chronic (three daily morphine injections for 4 days) injection, or chronic infusion (7 days via implanted osmotic minipumps). Although there were differences in the magnitude of withdrawal jumping between the three different morphine administration paradigms, large and significant strain differences were observed for each. In addition, the same strains were unusually sensitive or, conversely, altogether refractory to withdrawal jumping across all morphine treatment conditions. Overall, strain jumping means between acute and chronic dependence paradigms displayed a high degree of genetic correlation (r=0.87-0.95). The significant correlation between chronic morphine injection and continuous morphine infusion discounts the possible confounding effect of contextual learning and spontaneous withdrawal between chronic injections on the assessment of naloxone-precipitated withdrawal. Substantial heritability was also observed for acute and both paradigms of chronic dependence, with estimates ranging from h(2)=0.53 to 0.70. The present demonstration of a strong genetic correlation between physical dependence to morphine following acute and chronic treatment implies that genes associated with variable sensitivity in the two traits are the same, and is suggestive of shared physiological substrates. The data also demonstrate that the differential genetic liability to morphine physical dependence begins with, and is predicted by, the first morphine exposure.

Acute Disease↗
PubMed2004

Nicotine withdrawal induces subsensitivity of hypothalamic-pituitary-adrenal axis to stress in rats: implications for precipitation of depression during smoking cessation.

Epidemiologic studies show that smokers with a past history of depression are more likely to relapse into depression after smoking cessation than those without a history of depression. These studies suggest the existence of a direct biological link between nicotine withdrawal and depression. To investigate the neuronal and hormonal mechanisms of the precipitation of depression during smoking cessation, we used an animal model of nicotine withdrawal and studied the function of the hypothalamic-pituitary-adrenal (HPA) axis, the abnormality of which is implicated in the pathogenesis of depression. Rats were implanted with a minipump delivering nicotine at 6.0 mg/kg/day for 12 days. The minipumps were removed in order to abruptly terminate nicotine infusion. The activity of the HPA axis was determined on day 2 of withdrawal using the stress-induced corticosterone response and the dexamethasone suppression test (DST). At the same time the expressions of glucocorticoid receptor (GR) mRNA in the hippocampus and paraventricular nucleus of hypothalamus (PVN) and corticotropin-releasing hormone (CRH) mRNA in PVN were determined by non-radioactive in situ hybridization. Nicotine withdrawal resulted in lower corticosterone levels during restraint stress, suggesting subsensitivity of the HPA axis to stress. The result of DST, however, did not show a significant difference between nicotine-withdrawal and control rats. These effects of nicotine withdrawal were not accompanied by any changes in the expressions of GR and CRH mRNA in either hippocampus or PVN. These results suggest that subsensitivity of the HPA axis to stress during nicotine withdrawal may be implicated in the precipitation of depression during smoking cessation, although GR and CRH in the HPA axis do not appear to play a significant role.

Adaptation, Physiological↗
PubMed1985

Chromatographic profiles at E-280 nm for urinary precipitates in morbus Rett.

Previously we have observed different characteristic chromatographic ultraviolet absorbancy profiles at 280 nm for urinary protein precipitates from patients with behavioral disorders. The purpose with this study was to look for similar changes in urinary protein excretion from the grossly disabled patients with the Rett syndrome. Benzoic acid precipitates from the urine from 20 patients were chromatographed on a Sephadex G-25 gel column. There appeared 3 different profiles: 6 as observed in normal controls, 5 like that in compulsive behavior, and 9 were similar to those observed for autistiform-schizophreniform patients. The profiles did not mirror the behavioral observations for the patients, although the first group of 6 patients were the least disabled, whereas the last 9 patients were the most seriously ill. In conclusion the chromatographic profiles suggest a heterogeneous group of patients, but we need more observations for several patients over time, as there may be a change with the exacerbation of the disease.

Adolescent↗
PubMed1997

Dopamine D2 receptor availability in opiate-dependent subjects before and after naloxone-precipitated withdrawal.

Dopamine may play a role in opiate withdrawal and dependence. We measured dopamine D2 receptor availability in 11 opiate-dependent subjects using PFT and [11C]raclopride at baseline and during naloxone-precipitated withdrawal. Because [11C]raclopride is sensitive to endogenous dopamine, this strategy enabled us to test whether we could document in humans the DA reductions reported in animal models of opiate withdrawal. Results were compared with values from 11 controls, two of which also received naloxone. The ratio of the distribution volume in striatum to that in cerebellum (Bmax/Kd + 1) was used as model parameter for D2 receptor availability. Baseline measures for Bmax/Kd were lower in opiate-dependent subjects (2.44 +/- 0.4) than in controls (2.97 +/- 0.45 P < or = .009). Naloxone precipitated an intense withdrawal in the abusers but did not change the Bmax/Kd ratio. This study documents decreases in D2 receptors in opiate-dependent subjects but does not document significant changes in striatal DA concentration during acute withdrawal.

Adult↗
PubMed1999

Cholecystokinin receptor agonists block the jumping behaviour precipitated in morphine-dependent mice by naloxone.

The aim of present study was to reveal the role of cholecystokinin (CCK) in the jumping behaviour induced by the opioid antagonist naloxone (30 mg/kg) after the acute administration of morphine (200 mg/kg) in mice. Treatment with caerulein (0.01-1 microg/kg), a nonselective agonist of CCK receptors, induced a large reduction of jumping frequency without parallel suppression of locomotor activity. The CCK(B) receptor agonist CCK tetrapeptide (CCK-4. 0.125-32 mg/kg) caused the same effect, but it happened at much higher doses (above 0.5 mg/kg). Devazepide (1 microg/kg), a preferential CCK(A) receptor antagonist, completely reversed the action of caerulein (0.1 gmg/kg) and CCK-4 (2 mg/kg). A preferential CCK(B) receptor antagonists LY 288,513 at a high dose (4 mg/kg) blocked the action of CCK-4, but not that of caerulein. Acetorphan (16-128 mg/kg), an inhibitor of enkephalin metabolism, did not block naloxone-precipitated jumping behaviour. However, the combination of subthreshold doses of caerulein (0.001 microg/kg) and CCK-4 (0.25 mg/kg) with acetorphan (64 mg/kg) potently antagonized the behaviour induced by naloxone. In conclusion, the antagonism of CCK agonists against naloxone-precipitated jumping behaviour is apparently mediated via the CCK(A) receptor subtype. The stimulation of CCK(A) receptors seems to increase the release of endogenous enkephalins.

Animals↗
PubMed1999

A retarded boy with seizures precipitated by stepping into the bath water.

This report describes the unusual case of a boy with partial deletion in the proximal region of a long arm of chromosome 2 and reflex epilepsy. Seizures with identical onset were precipitated predictably by two independent triggers, micturition and immersion of the feet in tepid or hot water. A seizure precipitated by immersion could be reproduced under video and EEG monitoring. The EEG seizure onset was in the central midline region.

Child↗
PubMed1999

Removal of salt and organic acids from solution used to season salted Japanese apricots (ume) by electrodialysis, precipitation and adsorption.

With the aim of repeatedly reusing the solution used to season salted ume (Japanese apricot), we investigated its desalting and deacidification by electrodialysis, precipitation, and adsorption. Although NaCl and acids could be easily removed from used seasoning solution by electrodialysis, useful substances such as amino acids were removed at the same time. Precipitation using Ca(OH)2 could remove only organic acids, but the treated solution became bitter. Two weakly basic commercial resins, DIAION WA30 and Chitopearl CCS, adsorbed organic acids selectively. Chitopearl CCS in particular selectively adsorbed citric acid in the used seasoning solution without also adsorbing useful substances. The equilibrium data of a citric acid, which was a main organic acid, were correlated by the Langmuir equation. The saturation capacity decreased with increasing concentrations of NaCl in the solution but the equilibrium constant did not change. By combining electrodialysis and adsorption, NaCl and organic acids could be removed while amino acids largely remained. The resultant solution was considered to be suitable for repeated reuse.

Journal Article↗
PubMed2006

Symptomatic hyperlactataemia precipitated by the addition of tetracycline to combination antiretroviral therapy.

Hyperlactataemia in the setting of combination antiretroviral therapy for HIV infection occurs on a spectrum ranging from common, asymptomatic laboratory abnormalities to rare, potentially life-threatening lactic acidosis. Some other medications, including the biguanides, tetracycline, and even linezolid, have rarely been reported to cause lactic acidosis. Recently, cases of lactic acidosis or hyperlactataemia have been reported in patients receiving combination antiretroviral therapy that have been precipitated by the addition of other medications-eg, metformin or ribavirin. We report a case of symptomatic hyperlactataemia in a patient on combination antiretroviral therapy that was likely precipitated by the addition of tetracycline and discuss the broader implications of other medications with the potential to cause hyperlactataemia in the setting of combination antiretroviral therapy.

Acidosis, Lactic↗
PubMed2003

Protein purification by affinity precipitation.

Developing the most efficient strategy for the purification of a (recombinant) protein especially at large scale remains a challenge. A typical problem of the downstream process of mammalian cell products is, for instance, the early capture of the highly diluted product from the complex process stream. Affinity precipitation has been suggested in this context. The technique is known for over 20 years, but has recently received more attention due to the development of new materials for its implementation, but also because it seems ideally suited to specific product capture at large scale. The present review gives a comprehensive overview over this technique. Besides an introduction to the basic principle and a brief summary of the historical development, the main focus is on the current state-of-art of the technique, the available materials, important recent applications, as well as process design strategies and operating procedures. Special consideration is given to affinity precipitation for product recovery at large scale.

Chromatography, Affinity↗