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At least 703 records · Page 39Linked to original sources

PubMed2006

Pretreatment with probucol attenuates cardiomyocyte apoptosis in a rabbit model of ischemia/reperfusion.

OBJECTIVE: Apoptosis plays an important role in ischemic reperfusion injury. Probucol is a hypolipidemic agent and has antioxidant activity, which may inhibit the oxidative modification of low-density lipoprotein cholesterol. Studies have demonstrated that probucol improves left ventricular function, prevents left ventricular dilatation, and reduces cardiac fibrosis. However, the exact mechanism of probucol on the cardioprotective effect is not known. The objective of the present study was to examine the effect of probucol on ischemia/reperfusion-induced cardiomyocyte apoptosis. MATERIAL AND METHODS: Thirty male New Zealand White rabbits were randomly divided into sham, control, and treated groups, each group comprising 10 rabbits. Before establishment of the ischemia/reperfusion model, animals in the treated group were additionally fed daily with probucol (1000 mg per day) for 4 weeks. In the sham group, the heart was exposed after the chest had been opened, but the coronary artery was not ligated. The animals were killed 150 min after the procedure. In the other two groups, the rabbits were subjected to 30-min of coronary occlusion followed by a 2-h reperfusion. A blood sample was drawn from the right atrium before the animal was killed. The apoptotic myocytes were detected by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling. Expression of caspase-3 and mitochondrial cytochrome c release was detected by immunohistochemical analysis and Western blot analysis. The level of serum superoxide dismutase (SOD) was tested using the xanthine oxidase method, and the content of serum malondialdehyde (MDA) was measured by colorimetry. RESULTS: As compared with the sham group, the control group had a significantly higher apoptotic index ((32.48 +/- 4.56) % versus (0.56 +/- 0.18) %, p < 0.01) and serum MDA concentration (2.70 +/- 0.64 versus 1.06 +/- 0.46 micromol/L, p < 0.01), and a significantly lower serum SOD level (144.27 +/- 21.69 versus 204.64 +/- 16.67 microU/L, p < 0.01). Probucol pretreatment apparently caused a decrease in the apoptotic index ((21.64 +/- 3.08) %, p < 0.01 versus the sham or control group) and serum MDA concentration (1.95 +/- 0.51 micromol/L, p < 0.01 versus the sham or control group), and increased the levels of serum SOD (162.61 +/- 16.13 microU/L, p < 0.01 versus the sham group; p < 0.05 versus the control group). The caspase-3 activation and mitochondrial cytochrome c release in the control group were also higher than those in the treated group (p < 0.01). CONCLUSIONS: The present study shows that probucol attenuates ischemia/reperfusion-induced cardiomyocyte apoptosis. The protective effect of probucol on the myocardium may be partly due to its antioxidant activity.

Animals↗

PubMed1980

Sol particle immunoassay (SPIA).

We describe the use of inorganic (metal) colloidal particles as a label for immunoassays. Dose-response curves for human placental lactogen (HPL) and human chorionic gonadotrophin (HCG) were obtained with sandwich immunoassays, using conjugates consisting of antibody-coated colloidal gold or silver particles. Several techniques were used to measure the amount of bound conjugate, viz. colorimetry and carbon rod atomic absorption spectrophotometry (CRAAS). At higher antigen concentrations the results of the assay could be read by the naked eye. Using gold particles as label and CRAAS as detection method, we found a detection limit for a sandwich HPL sol particle immunoassay (SPIA) of 1,4 pmol/l, which was equal to that of an optimalized competitive radioimmunoassay. When using a colorimeter the detection limit for HPL of this SPIA was 5,4 pmol/l, which was superior to that of a corresponding sandwich enzyme-immunoassay (EIA). HPL and HCG were also simultaneously determined, using microtitration plates, coated with a mixture of anti-HPL and anti-HCG, and a mixture of silver particle anti-HPL conjugate and gold particle anti-HCG conjugate. CRAAS was used to measure the bound amount of silver and gold conjugate. This simultaneous assay requires more work in order to obtain better sensitivities.

Absorption↗

PubMed2000

Modification of the ion exchange HPLC procedure for the detection of nitrate and nitrite in dairy products.

Existing ion exchange HPLC methodology for nitrate and nitrite analysis in cured meat products suffers from high analyte variability at low concentrations and also chromatographic interference by artifacts in some other foods, such as dairy products. An investigation into the sources of variability has shown that both the cyclohexyl solid phase extraction cartridge and the glass fibre filter used in the original method can introduce artifacts which interfere with the determination of the nitrate in foodstuffs. We have also found that the use of a graphitized solid phase extraction cartridge used in tandem with the cyclohexyl solid phase extraction cartridge removed the artifacts from the chromatograph of dairy products that co-eluted with nitrite and nitrate. Values for the nitrite and nitrate content of dairy products were obtained by the HPLC procedure using these two solid phase extraction cartridges and the values obtained were in close agreement with those obtained by cadmium column reduction and colorimetry.

Chromatography, High Pressure Liquid↗

PubMedDate not supplied

Lysozyme: just an additive or a technological aid as well?

The effects of lysozyme on coagulation of milk and cheese making were studied by means of the gelograph, tristimulus colorimetry, ANS-fluorescence (hydrophobicity) and SDS-PAGE. Lysozyme binding to caseins caused structural differences during coagulation and it is proposed that, if the products have similar qualitative properties, lysozyme might be used as a technological aid giving shorter clotting times and higher yields.

Animals↗

PubMed2005

Formulation and in vitro evaluation of ethyl cellulose microspheres containing zidovudine.

The aim of this study was to formulate and evaluate microencapsulated controlled release preparations of zidovudine using ethyl cellulose as the retardant material with high entrapment efficiency and extended release. Microspheres were prepared by water-in-oil-in-oil (w/o/o) double emulsion solvent diffusion method. A mixed solvent system (MSS) consisting of acetonitrile and dichloromethane in a 1:1 ratio and light liquid paraffin were chosen as primary and secondary oil phases, respectively. Span 80 was used as the surfactant for stabilizing the secondary oil phase. The prepared microspheres were white, free flowing and spherical in shape and characterized by drug loading, infrared spectroscopy (IR), differential scanning colorimetry (DSC) and scanning electron microscopy (SEM). The in vitro release studies were performed using PH 7.4 phosphate buffer. The drug loaded microspheres showed 41-55% of entrapment and release was extended up to 18-20 h. The infrared spectra and DSC and DTA thermograms showed stable character of zidovudine in the drug loaded microspheres and revealed the absence of drug-polymer interactions. SEM studies showed that the microspheres are spherical and porous in nature. Data obtained from in vitro release were fitted to various kinetic models and high correlation was obtained in the Higuchi model. The drug release was found to be diffusion controlled.

Anti-HIV Agents↗

PubMed1981

Variability in the content and composition of alkaloids found in Canadian ergot. II. Wheat.

The total alkaloid content and individual alkaloid composition were determined by colorimetry and high performance liquid chromatography, respectively, for Canadian wheat ergot sclerotia. The total alkaloid content was highly variable between individual sclerotia from the same or different sources and ranged from 0.013 to 0.307%; the overall average for bulked samples from 75 sites was 0.163%. Ergocristine and its isomer ergocristinine were the major constituents (approximately 46%). Other alkaloid pairs observed were ergotamine (approximately 17%), ergocryptine (approximately 12%), ergocornine (approximately 11%), ergometrine (approximately 7%), and ergosine (approximately 5%), plus about 2% unidentified alkaloids.

Canada↗

PubMed1982

Variability in the content and composition of alkaloid found in Canadian ergot. III. Triticale and barley.

The total alkaloid content and individual alkaloid composition were determined by colorimetry and high performance liquid chromatography, respectively, for Canadian triticale and barley ergot (Claviceps purpurea). The total alkaloid content was highly variable between individual sclerotia from the same or different sources and ranged from 0.042 to 0.752% for triticale and from 0.082 to 1.04% for barley; average values were 0.239% for Ottawa triticale, 0.289% for Prairie triticale, and 0.264% for barley. Ergocristine and its isomer ergocristinine were the major constituents in both grains. On average, Canadian ergot pooled from rye, wheat, triticale, and barley consists of ergocristine (31%), ergocristinine (13%), ergocristinine (13%), ergotamine (17%), ergotaminine (8%), ergocryptine (5%), ergocryptinine (3%), ergometrine (5%), ergometrinine (2%), ergosine (4%), ergostinine (2%), ergocornine (4%), ergocorninine (2%), and unidentified alkaloids (3%), and an average total alkaloid content of 0.236%. With the exception of rye and barley ergot from the maritime regions, Canadian rye, wheat, triticale, and barley ergot is fairly uniform in individual alkaloid composition.

Canada↗

PubMed2004

Role of plasma homocysteine and lipoprotein (a) in coronary artery disease.

This study looks at the possible role of some non-traditional risk factors for premature coronary artery disease (CAD) and assesses the presence of relationship between these factors and the traditional cardiovascular risk factors. The study subjects (n=45) are divided into three groups comprising 15 premature CAD patients without traditional cardiovascular risk factors (group I); 15 premature CAD patients with one or more traditional cardiovascular risk factors (group II); and 15 healthy normal control subjects matched for age and sex (group III). Estimation of plasma homocysteine (Hcy) and plasminogen activator inhibitor-1 (PAI-1) is performed by enzyme-linked immunosorbent assay (ELISA); plasma folic acid by radioimmunoassay; plasma lipoprotein a (Lpa) by turbidimetry; and plasma lipids by colorimetry. Results showed a significant association between elevated Hcy and low folate levels and premature CAD in both patient groups. Also, a significant association was seen between elevated PAI-1 and CAD in the two patient groups, and between CAD and high levels of Hcy and triglycerides, as well as a low level of high-density lipoprotein cholesterol. Lpa showed significant association with premature CAD only in group II. Thus, Hcy, folic acid and PAI-1 might serve as independent risk factors for premature CAD in patients both with and without traditional coronary risk factors. However, Lpa might confer an additional coronary risk factor only in the presence of traditional risk factors.

Adult↗

PubMed2005

Methods of quantitative analysis of the nitric oxide metabolites nitrite and nitrate in human biological fluids.

In human organism, the gaseous radical molecule nitric oxide (NO) is produced in various cells from L-arginine by the catalytic action of NO synthases (NOS). The metabolic fate of NO includes oxidation to nitrate by oxyhaemoglobin in red blood cells and autoxidation in haemoglobin-free media to nitrite. Nitrate and nitrite circulate in blood and are excreted in urine. The concentration of these NO metabolites in the circulation and in the urine can be used to measure NO synthesis in vivo under standardized low-nitrate diet. Circulating nitrite reflects constitutive endothelial NOS activity, whereas excretory nitrate indicates systemic NO production. Today, nitrite and nitrate can be measured in plasma, serum and urine of humans by various analytical methods based on different analytical principles, such as colorimetry, spectrophotometry, fluorescence, chemiluminescence, gas and liquid chromatography, electrophoresis and mass spectrometry. The aim of the present article is to give an overview of the most significant currently used quantitative methods of analysis of nitrite and nitrate in human biological fluids, namely plasma and urine. With minor exception, measurement of nitrite and nitrate by these methods requires method-dependent chemical conversion of these anions. Therefore, the underlying mechanisms and principles of these methods are also discussed. Despite the chemical simplicity of nitrite and nitrate, accurate and interference-free quantification of nitrite and nitrate in biological fluids as indicators of NO synthesis may be difficult. Thus, problems associated with dietary and laboratory ubiquity of these anions and other preanalytical and analytical factors are addressed. Eventually, the important issue of quality control, the use of commercially available assay kits, and the value of the mass spectrometry methodology in this area are outlined.

Humans↗

PubMed2006

Maternal-fetal transport and disposition of copper, iron, molybdenum, selenium and zinc in experimentally induced diabetic rats.

OBJECTIVE: To assess maternal-fetal status of essential trace elements such as copper, iron, molybdenum, selenium and zinc, in experimentally induced diabetic and control pregnant rats, and to correlate the findings with those observed in human diabetic pregnancies. Fetal-maternal ratios of the elements and Cu:Zn and Cu:Fe ratios were also computed in control and study groups. METHODS: Diabetes was experimentally induced in pregnant Sprague Dawley rats by injection of streptozotocin. A cocktail of essential trace elements along with antipyrine as internal reference marker were then injected intra-peritoneally to diabetic and matched control pregnant rats on the 20th day of pregnancy. Maternal and fetal blood and tissue samples were collected after sacrificing the animals at 30- and 60-minutes following cocktail injection. Concentrations of trace elements and antipyrine in various blood and tissue samples were then determined by atomic absorption spectrophotometry and colorimetry, respectively. RESULTS: Concentrations of Cu, Fe, Mo, Se, Zn, and antipyrine averaged 2907.0 +/- 212.0 microg/L, 3950.0 +/- 766.0 microg/L, 15.8 +/- 1.7 microg/L, 74.8 +/- 6.5 microg/L, 726.4 +/- 67.4 microg/L, and 170.5 +/- 8.2 mg/L, respectively, in maternal blood in control pregnant rats (n = 5) at day 20 in the 30-minute study phase, while in the diabetic group (n = 5) the values of the various trace element concentrations and antipyrine averaged 2875.0 +/- 225.0 microg/L, 5875.0 +/- 688.0 microg/L, 21.2 +/- 2.1 microg/L, 116.0 +/- 3.6 microg/L, 753.0 +/- 71.3 microg/L, and 171.7 +/- 4.2 mg/L, respectively. Unpaired student's t-test showed that Fe and Se levels were significantly higher (p < 0.05) in the diabetic pregnant rats compared to controls. Cu, Mo and Zn values, however, were not significantly different (p > 0.05) between the two groups. Cu:Zn and Cu:Fe ratios showed varying differences between maternal and fetal samples in the control and study groups. CONCLUSIONS: Considering the disparity of results in pregnant diabetic rats and pregnant diabetic women, we urge exercising caution when comparing data from animal studies to human situations.

Animals↗

PubMed1989

A diffusive sampler for personal monitoring of toluene diisocyanate (TDI) exposure; Part I: Design of the dosimeter.

A passive dosimeter for monitoring occupational exposure to toluene diisocyanate (TDI) was developed. The device is constructed from a 37-mm aerosol cassette. The collection medium used in the dosimeter is 0.5% sulfuric acid (H2SO4). Membranes of both the permeation and diffusion types were evaluated for use in the dosimeter. Microporous Teflon diffusion membranes exhibited superior performance in terms of surface effects and residual TDI and were chosen for use. Collected TDI is determined as toluenediamine by either colorimetry using a modification of the Marcali technique or fluorometry using fluorescamine reagent. A significant dependence on wind speed was minimized by use of a second microporous membrane as a wind screen. The mass transfer rate of TDI was found to be approximately 0.0152 micrograms/ppb.hr and was equivalent for the 2,4 and 2,6 isomers of TDI.

Air Pollutants, Occupational↗

PubMed1978

ELISA: enzyme-linked immunosorbent assay.

Similar in design to radioimmunoassay, comparable in sensitivity and specificity but easier, safer, and less expensive, this new diagnostic technique uses enzyme-labeled rather than isotope-labeled reagents. The end point is a color change that can be assessed by colorimetry or with the naked eye. Various techniques of ELISA are described, along with examples of current and potential clinical applications.

Animals↗

PubMed2004

Nigerooligosaccharides augments mitogen-induced proliferation and suppresses activation-induced apoptosis of human peripheral blood mononuclear cells.

Nigerooligosaccharides (NOS), a mixture of nigerose and nigerosylmaltooligosaccharides, consists of immunopotentiating oligosaccharides found in foodstuffs. We have previously reported that activation of peripheral blood mononuclear cells (PBMC) in response to concanavalin A (Con A) or a streptococcal preparation of OK-432 is augmented in healthy young adults and elderly subjects after the intake of NOS-supplemented syrup. A reappraisal of the data suggests that NOS augments proliferation but partly suppresses activation-induced apoptosis of PBMC in response to these mitogens. To confirm this hypothesis, PBMC from healthy male subjects were stimulated with Con A or OK-432 in the presence of nigerose at the concentrations at which it was detected in the blood of subjects who had ingested NOS-supplemented syrup. Cellular activation, specifically metabolic demand, viability and proliferation, was assessed from glucose consumption, by WST-1 colorimetry and by 5-bromo-2'-deoxy-uridine incorporation assay, respectively. The Con A-induced activation of PBMC in each measurement was significantly augmented by nigerose. OK-432-induced decreases in the viability of PBMC were significantly inhibited by nigerose. Stimulation of PBMC with Con A or OK-432 induced apoptosis, but nigerose suppressed such activation-induced cell death. These results indicated that nigerose activated PBMC in vitro in a manner similar to the process observed in vivo, providing further evidence for the effectiveness of consumption of NOS-supplemented syrup.

Adult↗

PubMed2002

The validity of the Medisafe self-monitoring blood glucose system.

Self-monitoring blood glucose (SMBG) meters are widely used in the management of diabetes. The new SMBG meter Medisafe, which is based on the optoelectric colorimetry method, has been introduced. The objective of this study was to validate the Medisafe SMBG meters in comparison with the reference autoanalyzer (Hitachi 717) and to assess the repeatability of the instrument as well as variations of tip replacement. Samples of capillary and venous blood from 299 patients were tested. The correlation coefficients between the Medisafe-measured capillary and venous blood glucose levels and the reference autoanalyzer venous plasma glucose levels were 0.976 and 0.975, respectively. The range of differences from the reference value was examined; only 4% was in excess of +/- 20% of the reference laboratory value, and more than 40% of the values were within 5% of the reference laboratory value. Moreover, repeatability of the Medisafe capillary blood samples measured in three patients with three different blood glucose levels was determined. The coefficients of variation of blood glucose values are within 5%. In addition, the results of mean and SEM from each replication in three patients and glucose measurement from different lots of tips showed no significant difference (p > 0.05). It is concluded that the Medisafe SMBG meter has shown good results in terms of validity and repeatability. Furthermore, it provides safety from blood contamination, which is recommended in countries with a high prevalence of human immunodeficiency virus.

Adolescent↗

PubMed2003

Measurement of As, P, and S in the waste gases and water emitted from semiconductor processes by high-temperature hydrogen reduction gas chromatography.

A quick, sensitive, and accurate method, high-temperature hydrogen reduction gas chromatography (GC) (1,2), for measuring arsenic (As), phosphorus (P), and sulfur (S) in the waste gases and water emitted from semiconductor processes is proposed in this paper. A high-temperature hydrogen reduction system that changes As, P, S, and their compounds into hydrides by atomic hydrogen has been designed. It is convenient to detect these elements in solid, liquid, and gaseous samples by high-temperature hydrogen reduction GC without pretreating samples. The lower detection limits of As, P, and S by this method are 0.01, 0.003, 0.02 mg/L, respectively, and the values of relative standard deviation are 6.2%, 8.6%, and 0.3%, respectively. Results determined by high-temperature hydrogen reduction GC are primarily accordant to those by conventional methods such as colorimetry and ion chromatography. The error statistics of this analysis method also show that high-temperature hydrogen reduction GC can be successfully used to determine trace As, P, and S in waste gases and wastewater emitted from semiconductor processes.

Journal Article↗

PubMed2000

Loxapine intoxication: case report and literature review.

Loxapine is a dibenzoxazepine tricyclic compound used to treat schizophrenia in the United States since 1976. Metabolism includes demethylation to its primary metabolite, amoxapine. There are few documented reports of the disposition of loxapine in deaths due to overdose. This report discusses the overdose suicide of a 69-year-old white female found dead in her home by her husband. A prescription for loxapine (50-mg capsules) was found near the body. An autopsy was performed and heart blood, bile, vitreous humor, and gastric contents were submitted for toxicological analysis. The blood specimen was subjected to comprehensive testing that included volatile analysis by headspace gas chromatography (GC); acidic/neutral and basic drug screening by GC; benzodiazepine screening by high-performance liquid chromatography; opiate screening by modified immunoassay; and acetaminophen, salicylate, and ethchlorvynol screening by colorimetry. Loxapine and amoxapine were detected in the basic drug screen. No other drugs were detected in the case specimens. The respective concentrations of loxapine and amoxapine in each specimen were as follows: heart blood, 9.5 and 0.6 mg/L; bile, 28.8 and 4.7 mg/L; gastric, 278 mg/L and negative; and vitreous, 1.5 mg/L and negative. A review of the literature showed that the heart blood concentration of loxapine measured in this case was the highest reported to date. Based on the autopsy findings, patient history, and toxicology results, the cause of death was determined to be acute intoxication of loxapine and the manner, suicide.

Aged↗

PubMed2001

Rapid detection of benzoylecgonine in vitreous humor by enzyme immunoassay.

The usual specimens submitted by a medical examiner for toxicological analysis include blood, urine, bile, vitreous humor, stomach contents, and solid-organ tissue. The detection of drugs in these specimens typically involves a combination of techniques including colorimetry, immunoassay, and gas chromatography. Although many laboratories rely principally on urine for the detection of drugs of abuse by immunoassay, these assays may be applied to other specimen types. An evaluation of Microgenics Corporation's cloned enzyme donor immunoassay (CEDIA) was conducted in order to evaluate its use in the detection of cocaine/cocaine metabolites in vitreous humor specimens. During a 14-month period, 392 vitreous humor specimens were analyzed by the CEDIA DAU Cocaine assay. Instrument parameters were set according to published manufacturer's guidelines. All presumptive positive immunoassay results prompted confirmatory testing and quantitation by gas chromatography-mass spectrometry (GC-MS) of other specimens including blood. Vitreous humor specimens were not tested by GC-MS. Using a approximately 100-ng/mL cutoff, the CEDIA assay produced 23 presumptive positive results, 22 of which were confirmed by GC-MS. The only specimen which could not be confirmed, elicited an immunoassay screen value near the cutoff limit. Routine analysis of blood, urine, bile, and/or bladder wash specimens by gas chromatography-nitrogen phosphorus detection revealed the presence of cocaine/cocaine metabolites in only 7 (31.8%) of the 22 confirmed cases. The concentration ranges of cocaine and benzoylecgonine in the blood specimens were none detected to 337 ng/mL and 17 to 8598 ng/mL, respectively. Cocaethylene was not detected in these cases. Analysis of vitreous humor specimens by CEDIA improved the detection rate of cocaine/cocaine metabolites by 0.7% in the cases submitted to our laboratory during the 14-month period.

Autopsy↗

PubMedDate not supplied

Analysis of arsenic in forensic cases utilizing a rapid, non-ashing technique and furnace atomic absorption.

A procedure is described for analysis of arsenic in urine, hair, liver, and other biological specimens after dissolution of milligram quantities in nitric acid followed by treatment with nickel nitrate and graphite furnace atomic absorption (AA). Some data is given comparing silver diethyldithiocarbamate (AgDDC) colorimetry results to AA results. The method is fast, sensitive, and accurate. Case reports are cited.

Adult↗