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PubMed2005

Block of delayed-rectifier potassium channels by reduced haloperidol and related compounds in mouse cortical neurons.

Haloperidol is known as an antagonist of dopamine D2 receptors. However, it also blocks a variety of ion channels at concentrations above the therapeutic range. Reduced haloperidol (R-haloperidol), one of the main metabolites of haloperidol, has been reported to accumulate in certain tissues, particularly in brain cortex, and it may produce the pharmacological effects associated with haloperidol treatment. In this study, we assessed the effect of R-haloperidol and other related compounds on native delayed-rectifier potassium channels (K(DR)) in mouse cortical neurons by using the whole-cell patch-clamp technique. Although R-haloperidol has much lower affinity to D2 receptors than haloperidol, the IC50 of R-haloperidol to block K(DR) currents was 4.4 microM, similar to its parent compound. The binding site of R-haloperidol is on the cytoplasmic side of the channel because its quaternary derivative preferentially inhibited the currents from intracellular side. 4-Chlorophenyl-4-hydroxypiperidine (4C4HP) is the active fragment of haloperidol because other compounds containing this moiety, including L-741,626 (3-[4-(4-chlorophenyl)-4-hydroxypiperidin-L-yl]-methyl-1H-indole) and loperamide, also blocked K(DR) channels. The potency of the 4C4HP fragment positively correlated with the hydrophobicity index (clogP) of the compounds tested. We conclude that R-haloperidol is a K(DR) channel blocker, although it does not interfere with the normal channel function at a clinically relevant concentration.

Animals↗
PubMed2004

Effects of MgO-CaO-P2O5-Na2O-based additives on mechanical and biological properties of hydroxyapatite.

In this research, we improved densification, hardness, and compression strength of synthetic hydroxyapatite (HAp) ceramics by introducing small quantities of MgO-CaO-P(2)O(5)-Na(2)O-based sintering additives. Biological properties of HAp were not altered by this procedure. Phase analyses were performed by using a Philips Xpert fully automated diffractometer with Co K-alpha radiation to understand the influence of additives on phase purity in the final products. All compositions were characterized at green and sintered densities to understand the influence of additives on densification. Some of the compositions showed >40% increase in Vickers microhardness compared with pure HAp processed under the same conditions. Improvement in compression strength was also detected in some compositions. In vitro biological testing used a modified human osteoblast cell line to test biocompatibility, cell attachment, and cell proliferation. All these compositions were nontoxic and biocompatible. Our results indicate that MgO-CaO-P(2)O(5)-Na(2)O-based sintering additives can be used to improve both mechanical and biological properties of HAp ceramics.

Biocompatible Materials↗
PubMed2004

A facile preparation of uronates via selective oxidation with TEMPO/KBr/Ca(OCl)(2) under aqueous conditions.

Addition of solid Ca(OCl)(2) as the terminal oxidant in the TEMPO-mediated selective oxidation has the benefit of easier operation. A variety of partially protected saccharide derivatives (1a-l) have been successfully converted into the corresponding uronate derivatives, including disaccharide building blocks for GAG fragments and precursors to saponins. The beneficial effect of Aliquat 336 was also disclosed in the oxidation of certain substrates.

Bromides↗
PubMed1999

Reduction of the nociceptive response to gastric distension by nitrate ingestion in rats.

BACKGROUND: Dietary nitrates are known to produce nitric oxide in the stomach, which may influence gastric function. AIM: To investigate whether nitrate ingestion modifies gastric sensitivity to distension through a mechanism involving nitric oxide production. METHODS: Nociception, associated with gastric distension ranging from 10 to 40 mmHg, was assessed in anaesthetized rats by the amplitude of cardiovascular depressor responses. Gastric volume corresponding to each distension was recorded. The following intragastric administrations (1 mL) were performed before distension: water (control), KNO3, NaNO3, KCl, NaCl (all at 0.1 mmol/kg), standard food (0.5 g), sodium nitroprusside, a nitric oxide donor (5 mg/kg), and haemoglobin, a nitric oxide scavenger (150 mg/kg) given either with water or KNO3. RESULTS: In controls, the fall in blood pressure increased from 7.8 +/- 2.0 to 31.6 +/- 2. 7 mmHg at distending pressures from 10 to 40 mmHg, respectively. KNO3 significantly reduced the amplitude of blood pressure response for the highest distending pressures (35 and 40 mmHg), while KCl induced a reduction in blood pressure response at all gastric pressures. NaNO3 and NaCl did not induce significant changes in distension-induced depressor responses. Administration of 0.5 g of standard food or sodium nitroprusside reproduced the effect of KNO3, which was reversed by haemoglobin. None of the compounds modified the gastric pressure-volume relationship, except KNO3, which increased gastric volume for the lowest distending pressures, and haemoglobin, which reduced the volume for the highest pressure. CONCLUSIONS: Ingestion of potassium nitrate reduces the sensitivity to gastric distension, through a mechanism involving nitric oxide.

Animals↗
PubMed2001

Inactivation of root canal medicaments by dentine, hydroxylapatite and bovine serum albumin.

AIM: This study examined and compared the inhibition of the antibacterial effect of saturated calcium hydroxide solution, chlorhexidine acetate and iodine potassium iodide by dentine, hydroxylapatite and bovine serum albumin. METHODOLOGY: Enterococcus faecalis strain A197A prepared to a suspension of 3 x 10(8) cells per ml in 0.5% peptone water was used. Fifty microL of saturated calcium hydroxide solution, 0.05% chlorhexidine acetate or 0.2/0.4% iodine potassium iodide were incubated at 37 degrees C with 28 mg dentine powder (DP), hydroxylapatite (HA) or bovine serum albumin (BSA) in 50 microL water for 1 h before adding 50 microL of the bacterial suspension. Samples for bacterial culturing were taken from the suspension 1 and 24 h after adding the bacteria. In further experiments, the amount of dentine was stepwise reduced from 28 mg 150 microL-1 to 2.8 mg 150 microL-1. RESULTS: Calcium hydroxide was totally inactivated by the presence of 28 mg of DP, HA or BSA. Chlorhexidine (0.05%) was strongly inhibited by BSA and slowed down by dentine. However, HA had little or no inhibitory effect on chlorhexidine. The antibacterial effect of 0.2/0.4% iodine potassium iodide on E. faecalis was totally inhibited by dentine (28 mg), but was practically unaffected by HA or BSA. A stepwise reduction of dentine from 28 mg 150 microL-1 to 2.8 mg 150 microL-1 was followed by a similar reduction of the inhibition of the antibacterial activity of chlorhexidine. Iodine potassium iodide was not inhibited at all with dentine amounts less than 28 mg. However, the effect of saturated calcium hydroxide solution was totally eliminated by dentine, in all four concentrations. CONCLUSION: Inhibition by dentine of the antibacterial activity of calcium hydroxide, chlorhexidine and iodine potassium iodide occurs by different mechanisms. Different components of dentine may be responsible for the inhibition of these three medicaments. Calcium hydroxide was particularly sensitive to inhibition by both inorganic and organic compounds.

Animals↗
PubMed2002

Comparison of Amsorb, sodalime, and Baralyme degradation of volatile anesthetics and formation of carbon monoxide and compound a in swine in vivo.

BACKGROUND: Consequences of volatile anesthetic degradation by carbon dioxide absorbents that contain strong base include formation of compound A from sevoflurane, formation of carbon monoxide (CO) and CO toxicity from desflurane, enflurane and isoflurane, delayed inhalation induction, and increased anesthetic costs. Amsorb (Armstrong Ltd., Coleraine, Northern Ireland) is a new absorbent that does not contain strong base and does not form CO or compound A in vitro. This investigation compared Amsorb, Baralyme (Chemetron Medical Division, Allied Healthcare Products, St. Louis, MO), and sodalime effects on CO (from desflurane and isoflurane) and compound A formation, carboxyhemoglobin (COHb) concentrations, and anesthetic degradation in a clinically relevant porcine in vivo model. METHODS: Pigs were anesthetized with desflurane, isoflurane, or sevoflurane, using fresh or partially dehydrated Amsorb, Baralyme, and new and old formulations of sodalime. Anesthetic concentrations in the fresh (preabsorber), inspired (postabsorber), and end-tidal gas were measured, as were inspired CO and compound A concentrations and blood oxyhemoglobin and COHb concentrations. RESULTS: For desflurane and isoflurane, the order of inspired CO and COHb formation was dehydrated Baralyme >> soda-lime > Amsorb. For desflurane and Baralyme, peak CO was 9,700 +/- 5,100 parts per million (ppm), and the increase in COHb was 37 +/- 14%. CO and COHb increases were undetectable with Amsorb. Oxyhemoglobin desaturation occurred with desflurane and Baralyme but not Amsorb or sodalime. The gap between inspired and end-tidal desflurane and isoflurane did not differ between the various dehydrated absorbents. Neither fresh nor dehydrated Amsorb caused compound A formation from sevoflurane. In contrast, Baralyme and sodalime caused 20-40 ppm compound A. The gap between inspired and end-tidal sevoflurane did not differ between fresh absorbents, but was Amsorb < sodalime < Baralyme with dehydrated absorbents. CONCLUSION: Amsorb caused minimal if any CO formation, minimal compound A formation regardless of absorbent hydration, and the least amount of sevoflurane degradation. An absorbent like Amsorb, which does not contain strong base or cause anesthetic degradation and formation of toxic products, may have benefit with respect to patient safety, inhalation induction, and anesthetic consumption (cost).

Absorption↗
PubMedDate not supplied

Effects of some chelating agents on the uptake and distribution of 54Mn(II) in the brown trout (Salmo trutta).

The effects of humic acids, which are natural metal-complexing compounds, and potassium ethylxanthate, sodium diethyldithiophosphate, sodium dimethyldithiocarbamate, and sodium diethyldithiocarbamate, which are sulphur-containing man-made chelating agents, on the uptake and tissue distribution of 54Mn(II) were studied in brown trout (Salmo trutta). Fish were exposed for 7 days to 0.1 microgram Mn(II).l-1 as MnCl2 (1 microCi 54MN.l-1) with or without chelating agents. Examination of the partition of Mn between octanol and a Tris-HCl buffer in the presence of these compounds was also performed. Humic acids had only small effects on Mn uptake and distribution in trout, probably because of the low stability of Mn-humate complexes. Partition of Mn in the presence of potassium ethylxanthate, sodium diethyldithiophosphate, sodium dimethyldithiocarbamate, and sodium diethyldithiocarbamate between octanol and Tris-HCl buffer showed formation of lipophilic complex with the latter two compounds, but not with the former. However, these four chelating agents all decreased Mn uptake in the trout by 40-45%. These substances also changed the distribution of Mn within the fish, with a higher proportion of the metal being present in some visceral organs and a smaller proportion being localized in some non-parenchymateous tissues, such as skins, fins and bones. The mechanisms underlying these effects are not known. However, the interaction of chelating agents with the Mn, although weak, may have partially withdrawn the metal from the uptake process in the gills. The redistribution of Mn in the fish may be due to the binding of the metal to complexing compounds which have reached the intestinal lumen.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2005

Bacterial Cr(VI) reduction concurrently improves sunflower (Helianthus Annuus L.) growth.

Four Cr(VI)-reducing bacterial strains (Ochrobactrum intermedium, CrT-2, CrT-3 and CrT-4) previously isolated from chromium-contaminated sites were inoculated on to seeds of sunflower (Helianthus annuus var SF-187), which were germinated and grown along with non-inoculated controls with chromate salts (300 microg CrCl3 or K2CrO4 ml(-1)). Severe reduction (20%) in seed germination was observed in Cr(VI) stress. Plant height decreased (36%) with Cr(VI) when compared with chromium-free control, while O. intermedium inoculation resulted a 20% increment in this parameter as compared to non-inoculated chromium-free control. CrT-3 inoculation resulted a 69% increment in auxin content as compared to non-inoculated control. O. intermedium caused 30% decrease in chromium uptake in sunflower plant roots under Cr(VI) stress as compared to chromium-free control plants.

Biodegradation, Environmental↗
PubMed1991

Assessments of lung digestion methods for recovery of fibers.

Evaluation of the pulmonary hazards associated with exposure to fibrous materials tends to be more complicated than assessments required for particulate materials. Fibers are defined by aspect ratios and it is generally considered that physical dimensions play an important role in the pathogenesis of fiber-related lung diseases. Several digestion techniques have been used to recover fibers from exposed lung tissue for clearance studies. Because many of the digestion fluids are corrosive (e.g., bleach, KOH), it is conceivable that the dimensions of recovered fibers are modified during the tissue digestion methods to assess whether the physical dimensions of bulk samples of fibers were altered following simulated digestion processing. Aliquots of crocidolite and chrysotile asbestos, Kevlar aramid, wollastonite, polyacrylonitrile (pan)-based carbon, and glass fibers were incubated with either saline, bleach, or KOH and then filtered. Scanning electron microscopy techniques were utilized to measure the physical dimensions (i.e., lengths and diameters) of at least 160 fibers per treatment group of each fiber type. Our results showed that the lengths and diameters of glass fibers and wollastonite were altered after treatment with KOH. In addition, treatment with bleach produced a small reduction in both asbestos fiber-type diameters, and greater changes in Kevlar and wollastonite diameters and carbon fiber lengths (P less than 0.05). These results indicate that lung digestion methods should be carefully assessed for each fiber type before initiating fiber clearance studies.

Asbestos↗
PubMed2001

Improved bonding of adhesive resin to sintered porcelain with the combination of acid etching and a two-liquid silane conditioner.

This study determined the bond strengths of adhesive resins joined to a feldspathic porcelain (VMK 68) for the purpose of developing the most durable surface preparation for the porcelain. Three porcelain surfaces-ground, air-abraded with alumina, and etched with hydrofluoric acid-were prepared. A two-liquid porcelain conditioner that contained both 4-methacryloyloxyethyl trimellitate anhydride (4-META) and a silane coupler (Porcelain Liner M) was used as the priming agent. Each of the two liquid components of the conditioner was also used individually in order to examine the effects of the respective chemical ingredients on adhesive bonding. Two methyl methacrylate (MMA)-based resins initiated with tri-n-butylborane (TBB) either with or without 4-META (MMA-TBB and 4-META/MMA-TBB resins) were used as the luting agents. Shear bond strengths were determined both before and after thermocycling. Shear testing results indicated that thermocycling was effective for disclosing poor bonding systems, and that both mechanical and chemical retention were indispensable for bonding the porcelain. Of the combinations assessed, etching with hydrofluoric acid followed by two-liquid priming with the Porcelain Liner M material generated the most durable bond strength (33.3 MPa) for the porcelain bonded with the 4-META/MMA-TBB resin (Super-Bond C&B).

Acid Etching, Dental↗
PubMed1992

Quantification of the degradation products of sevoflurane in two CO2 absorbants during low-flow anesthesia in surgical patients.

Sevoflurane, a new inhalational anesthetic agent has been shown to produce degradation products upon interaction with CO2 absorbants. Quantification of these sevoflurane degradation products during low-flow or closed circuit anesthesia in patients has not been well evaluated. The production of sevoflurane degradation products was evaluated using a low-flow anesthetic technique in patients receiving sevoflurane anesthesia in excess of 3 h. Sevoflurane anesthesia was administered to 16 patients using a circle absorption system with O2 flow of 500 ml/min and average N2O flow of 273 ml/min. Preoperative and postoperative hepatic and renal function studies were performed. Gas samples were obtained from the inhalation and exhalation limbs of the anesthetic circuit for degradation product analysis and analyzed by gas chromatography/mass spectrometry for four degradation products. The first eight patients received sevoflurane anesthesia using soda lime, and the following eight patients received anesthesia using baralyme as the CO2 absorbant. CO2 absorbant temperatures were measured during anesthesia. Of the degradation products analyzed, only one compound [fluoromethyl-2, 2-difluoro-1-(trifluoromethyl) vinyl ether], designated compound A, was detectable. Concentrations of compound A increased during the first 4 h of anesthesia with soda lime and baralyme and declined between 4 and 5 h when baralyme was used. Mean maximum inhalation concentration of compound A using baralyme was 20.28 +/- 8.6 ppm (mean +/- SEM) compared to 8.16 +/- 2.67 ppm obtained with soda lime, a difference that did not reach statistical significance. A single patient achieved a maximal concentration of 60.78 ppm during low-flow anesthesia with baralyme. Exhalation concentrations of compound A were less than inhalation concentrations, suggesting patient uptake.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorption↗
PubMed2004

[Mechanisms of muscovite on gastric mucosal protective effect].

OBJECTIVE: To explore the mechanisms of muscovite gastric mucosal protective effect. METHOD: Rat model of chronic gastritis were used. After gastric mucosal injury was induced, the rats were divided into 6 groups and were treated with different drugs. 2 weeks later, the tissue and blood samples were obtained and measured. RESULT: The general conditions, the observations under macroscopy, microscope and electron microscope of the middle and high dose of muscovite groups resembled those of the normal group. Their PH levels were higher than those of the model group, and the rates of intestinal metaplasia were lower, but the PGE2 level of the middle dose of muscovite group was the highest. CONCLUSION: Muscovite can be adsorbed on the surface of the gastric mucosa. It has gastric mucosal protective effect by improving excretion of mucus and synthesis of PGE2 in gastric mucosa, restraining gastric acid, reversing of intestinal metaplasia and decreasing inflammation cells.

Aluminum Compounds↗
PubMed2004

Green Or preparation in dentin hypersensitivity treatment.

The effectiveness of Green Or preparation in the treatment of cervical dental hypersensitivity was evaluated. This problem is difficult for patients and for dentists because of dual and unknown methods of treatment. The preparation was used in 30 patients between the ages of 20 and 70 years on 240 teeth with exposed and hypersensitive necks. The obtained results are acceptable, as total elimination of hypersensitivity was attained in 85% of cases, partial reduction of hypersensitivity in 15% cases.

Administration, Topical↗
PubMed1975

[Pathogenesis of disorders of cardiac rhythm and conductivity in acute organophasphate insecticide poisoning].

A dynamic examination of ECG and K and Na level in plasma and erythrocyte was conducted in 73 patients during the acute period of poisoning with phosphorus-organic insecticides -- thiophos, chlorophos, carbophos. In 18.6% of the cases severe rhythm and conductivity disorders were revealed that caused cardiac arrest and death in 29 patients. Besides, a sharp increase in the electric systole on the ECG was noted in all the patients during the acute period of poisoning. A study of the electrolytes revealed hypokalemia, hypernatremia and an increased content of K and Na in the erythrocytes. The authors believe that the disturbances in the cardiac activity during acute poisonings with phosphorus-organic insecticides are due to the effect of the excessive acetylcholine upon the ion permeability towards increasing intracellular potassium.

Acute Disease↗