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PubMedDate not supplied

A sensitive and specific method for the determination of total ribavirin in human red blood cells by liquid chromatography-tandem mass spectrometry.

A sensitive and specific method using high-performance liquid chromatography (LC)-tandem mass spectrometry (MS) for the analysis of total ribavirin in human red blood cells (RBC) is developed and validated. The method involves the addition of an internal standard and perchloric acid, the conversion of ribavirin phosphorylated metabolites to ribavirin, purification with a solid-phase exchange cartridge, and LC-MS-MS analysis. The MS-MS is selected to monitor m/z 245-113 for ribavirin and m/z 250-113 for [13C]ribavirin using positive electrospray ionization. The calibration curve is linear over a concentration of 100-10,000 ng/mL with a limit of quantitation of 100 ng/mL. Mean interassay accuracy for quality control (QC) at 100, 1000, and 10,000 ng/mL are 101.8%, 99.4%, and 98.8%, respectively. Mean interassay precision (%CV) for QC at 100, 1000, and 10,000 ng/mL are 5.0%, 5.0%, and 2.5%, respectively. Extractibility of total ribavirin from RBC is confirmed with RBC obtained from a [(14)C]ribavirin-dosed monkey. The method is used to determine the free and total ribavirin concentration in human RBC obtained from hepatitis C patients treated with ribavirin.

Antiviral Agents↗
PubMed1985

Metabolic damage to human saphenous vein during preparation for coronary artery bypass grafting.

Segments of saphenous vein from patients undergoing coronary artery by-pass graft surgery were frozen in liquid nitrogen immediately on dissection (control), after stripping of the adventitia and side branch ligation (manipulation), after distention with blood (distention), or at completion of the last proximal anastomosis (prepared vein). Vein was stored during the operation in patient's heparinised arterial blood at room temperature. Frozen vein was extracted with perchloric acid. ATP, ADP, and AMP, adenosine, inosine and hypoxanthine concentrations were measured by high pressure liquid chromatography. Prepared vein had ca 50% lower ATP concentrations and ATP/ADP ratio than control vein, higher concentrations of inosine and hypoxanthine and lower concentrations of AMP and adenosine. ATP concentration and ATP/ADP ratio did not correlate with the time elapsed between dissection and freezing of the prepared vein. The characteristic changes seen in prepared vein were not seen when control vein was simply stored in arterial blood at 23 degrees C, in normal saline at 23 degrees C or 4 degrees C, in Krebs-Ringer bicarbonate buffer at 37 degrees C or at St Thomas's Hospital cardioplegic solution at 4 degrees C. Distention with unlimited pressure did not distension at less than 300 mmHg gave rise to the same changes in ATP concentration and ATP/ADP ratio as in the prepared vein. These results show that vein suffered metabolic changes during preparation for bypass grafting and suggest that uncontrolled distention may contribute to these changes. Such biochemical measurements provide a quantitative estimate of tissue damage and allow objective comparison of different preparative techniques.

Adenine Nucleotides↗
PubMed1988

Quantitation of coronary venous adenosine in patients: limitations evaluated by radioimmunoassay.

Experimental studies have shown that adenosine is rapidly released in response to myocardial ischaemia. To evaluate whether coronary venous adenosine release is a metabolic characteristic of myocardial ischaemia in patients, adenosine concentrations were measured by a highly sensitive and specific radioimmunoassay. In three patients with normal coronary arteries and in seven with obstructive coronary artery disease coronary venous adenosine content was measured at rest and during atrial pacing. When whole blood or plasma were extracted immediately with perchloric acid the adenosine content was found to be lower than that previously reported. Recovery studies showed that the importance of time and temperature at low adenosine concentrations had been underestimated in preceding studies. In patients with coronary artery disease coronary venous adenosine concentration increased from 106.3(48.8) nmol.litre-1 to 114.9(57.0) nmol.litre-1 (NS) during pacing and was 130.4(63.3) nmol.litre-1 (NS) 2 min after pacing. Even in the presence of lactate production enhanced adenosine release was not consistently evidenced. Furthermore, venous adenosine content did not increase in five patients undergoing coronary artery occlusion during angioplasty of the left anterior descending coronary artery. The extremely short half life of coronary venous adenosine appears to preclude its use as an index of myocardial ischaemia in patients.

Adenosine↗
PubMed1992

Regulation of tissue noradrenaline in the rat myocardial infarction model of chronic heart failure.

OBJECTIVE: The aim was to evaluate mechanisms regulating tissue noradrenaline in congestive heart failure. METHODS: Tissue noradrenaline was measured in the conscious post myocardial infarction rat model of congestive heart failure and in sham operated rats (1) under control conditions, (2) 6 h after inhibition of tyrosine hydroxylase by the intraperitoneal administration of alpha-methyl-para-tyrosine (AMPT) (100 mg.kg-1 every 2 h), (3) 6 h after AMPT with desipramine pretreatment (0.3 mg.kg-1), and (4) following exhaustive exercise after AMPT. Tissue noradrenaline was extracted with perchloric acid and measured by high performance liquid chromatography with electrochemical detection. RESULTS: In control animals without drug, tissue noradrenaline concentration was lower in the following tissues in the rats with myocardial infarction compared with the sham operated group: left and right ventricles, spleen, soleus and white gastrocnemius muscles, kidney cortex, and tail artery. After AMPT, tissue noradrenaline concentration in the sham operated group was significantly lower than control; in the myocardial infarction group the fall in noradrenaline was only significant in the kidney, and group differences were no longer present. In the sham operated animals, coadministration of desipramine with AMPT attenuated the fall in tissue noradrenaline caused by AMPT in the heart and spleen. With exercise to exhaustion, cardiac noradrenaline was lower in rats with myocardial infarction than in sham operated rats, but higher in the soleus muscle. CONCLUSIONS: These data suggest that tissue noradrenaline depletion in congestive heart failure is not isolated to the heart, and it occurs despite activation of mechanisms that might be operating to conserve neuronal noradrenaline. One mechanism may be reduced organ blood flow to retard diffusion of noradrenaline into the circulation. If this increases interstitial noradrenaline concentration, it would facilitate prejunctional alpha 2 receptor restraint on noradrenaline release. Metabolic coronary vasodilatation during exercise reverses this process, and makes the heart most susceptible to noradrenaline depletion in congestive heart failure.

Animals↗
PubMedDate not supplied

Determination of ethylene glycol in postmortem blood by capillary gas chromatography.

A simple procedure for the determination of ethylene glycol in blood by capillary gas chromatography was developed. The proteins are precipitated by the addition of perchloric acid which includes the internal standard 1,2-butanediol. The extract is neutralized and the solution is directly injected. The assay is linear and the precision, expressed as coefficient of variation, is 4-11% (within run). The detection limit is about 0.05 g/L. The method also seems applicable for the determination of ethylene glycol in urine.

Chromatography, Gas↗
PubMed2002

Toxicological analysis of chlorhexidine in human serum using HPLC on a polymer-coated ODS column.

A simple and reliable high-performance liquid chromatographic (HPLC) method for analyzing chlorhexidine in human serum was developed. After the addition of an internal standard, levomepromazine, 0.2 mL serum was deproteinized with 10% perchloric acid. The acidic supernatant was neutralized with 1M potassium carbonate solution, and the insoluble salt was removed by centrifugation. An aliquot of the supernatant was applied to HPLC with UV detection (260 nm). HPLC separation was achieved on a polymer-coated ODS column equilibrated with acetonitrile/water containing 0.05% trifluoroacetic acid, 0.05% heptafluorobutyric acid, and 0.1% triethylamine (40:60, v/v). The calibration curve was linear in the concentration range from 0.05 to 50.0 microg/mL, and the lower limit of detection was 0.05 microg/mL. The accuracy and precision of the method were evaluated at concentrations of 0.5 microg/mL and 5.0 microg/mL. The coefficients of variation ranged from 4.0 to 4.5%. The concentration of chlorhexidine in the serum of a patient who died after a suspected intravenous injection of chlorhexidine gluconate was determined.

Anti-Infective Agents, Local↗
PubMed2002

Determination of cobalt in urine by FI-ICP-AES with online preconcentration.

A method for the preconcentration and determination of cobalt in human urine samples was developed. The online preconcentration and determination were attained using inductively coupled plasma atomic emission spectromety (ICP-AES) coupled to a flow injection (FI) method. Cobalt was retained on an Amberlite XAD-7 resin as cobalt-2-(5-bromo-2-pyridylazo)-5-diethylaminophenol complex at pH 9.5. Cobalt was removed from the microcolumn with perchloric acid. A sensitivity enhancement factor of 90 was obtained with respect to cobalt determination by ICP-AES without preconcentration. The value of detection limit for the preconcentration method proposed was 25 ng/L. The precision for 10 replicate determinations at the 5 mg/L (mean +/- SD, 5.1 +/- 0.14) Co level was 2.7% relative standard deviation, calculated from the peak heights obtained. The calibration graph preconcentration method for cobalt was linear with a correlation coefficient of 0.9994 from approximately 0.25 mg/L up to at least 100 mg/L. The method was successfully applied to the determination of cobalt in human urine samples.

Calibration↗
PubMed2003

Postmortem identification and quantitation of 2,5-dimethoxy-4-n-propylthiophenethylamine using GC-MSD and GC-NPD.

2,5-Dimethoxy-4-n-propylthiophenethylamine (2C-T-7) has structural and pharmacodynamic similarities to methylenedioxymethamphetamine (MDMA). This compound was initially identified from a routine screening procedure in postmortem urine from a 20-year-old male that died in a local emergency room after reportedly insufflating 35 mg. This report describes the development of a quantitative method for 2C-T-7. A number of method parameters were studied including internal standard selection, liquid-liquid extraction scheme, and drug stability in preserved refrigerated blood. The adopted method for blood and urine involves the addition of trimethoxyamphetamine (TMA) as internal standard, alkalinization with ammonium hydroxide, and liquid-liquid extraction with n-chlorobutane. To facilitate recovery from liver, a 1:4 aqueous homogenate was pretreated with dilute perchloric acid, centrifuged, and the supernatant was extracted as previously described. In each case, 0.1% hydrochloric acid in methanol was added during the final concentration step to prevent loss of drug caused by evaporation. Samples were analyzed by gas chromatography with nitrogen-phosphorus detection (GC-NPD) and electron ionization GC-mass spectrometry (MS) utilizing selected ion monitoring. For the GC-MS analysis, the characteristic ions monitored for 2C-T-7 were m/z 226, 255, and 183 and for TMA, m/z 182. The limits of detection and quantitation in blood were 6.0 and 15.6 ng/mL, respectively, by both GC-NPD and GC-MS. The results from the postmortem case were as follows: heart blood, 57 ng/mL; femoral blood, 100 ng/mL; urine, 1120 ng/mL; and liver, 854 ng/g.

Adult↗
PubMedDate not supplied

Arsine evolution-electrothermal atomic absorption method for the determination of nanogram levels of total arsenic in urine and water.

An arsine evolution-electrothermal atomic absorption method is described for the determination of ng/mL concentrations of total arsenic in urine and water. Organic-arsenic compounds are decomposed with nitric, sulfuric, and perchloric acids. Sodium borohydride, a redesigned hydride generator, and an electric-heated absorption tube are used for arsine evolution and its conversion to atomic arsenic. The method has a detection limit of 6 ng/mL, a sensitivity of 1 ng/mL, and is linear from 0 to 110 ng/mL of arsenic. Accuracy was established with two different National Bureau of Standards Standard Reference materials, and mean errors from 0 to -2 were obtained.

Arsenic↗
PubMedDate not supplied

Determination of phenol and pentachlorophenol in plasma and urine samples by gas liquid chromatography.

Gas chromatographic methods have been developed using a Supelco 1240-DA column for the determination of pentachlorophenol (PCP) in plasma and urine samples, and phenol in urine samples. These methods required no derivatization. Electron capture detection has been used for PCP determination, while flame ionization detection has been used to determine urinary phenol. The proposed phenol method avoids the use of perchloric acid, a safety hazard, as well as the formation of interfering compounds, which may be read as phenol if column resolution is inadequate.

Chlorophenols↗
PubMed1982

Influence of dietary zinc on rat brain catecholamines.

Weanling rats were fed a 20% sprayed egg white, zinc-deficient diet for 9 or 10 days. One group (zinc-deficient) was fed ad libitum and given distilled deionized water; a second group was individually pair-fed to rats in the zinc-deficient group; a third group was fed ad libitum; a fourth group was also fed ad libitum, but was fasted overnight prior to slaughter. The latter three groups were given 25 ppm zinc (as zinc acetate) in the water. The brain was excised and the catecholamines were extracted with 0.1 M perchloric acid separated by reverse phase HPLC and measured electrochemically. There did not appear to be a correlation between food intake and brain catecholamine concentrations in any of the groups examined. Brain norepinephrine concentrations in the zinc-deficient rats, however, were significantly higher than in the pair-fed or ad libitum-fed rats.

Animals↗
PubMed1988

Effect of dietary zinc deficiency and the associated drop in voluntary food intake on rat erythrocyte membrane polyamines.

The effect of dietary zinc deficiency in the rat on the free (noncovalently bound) polyamine concentrations in erythrocyte membranes, in erythrocyte cytosol and in the blood plasma were determined. Weanling male Wistar rats were fed an egg white-based diet containing less than 1.0 mg Zn/kg diet for 3 wk ad libitum. Control rats were either pair-fed or ad libitum-fed the basal diet supplemented with 100 mg Zn/kg diet. Tissue fractions were extracted with 0.2 M perchloric acid and polyamines were measured in the soluble fraction by dansylation, thin-layer chromatography and fluorescence spectrophotometry of the isolated dansylated polyamines. The depressed food intake associated with dietary zinc deficiency caused significantly (P less than 0.05) lower plasma spermidine, erythrocyte cytosol putrescine, spermidine and spermine and erythrocyte membrane spermidine concentrations. In addition, the depressed food intake caused significantly lower spermidine-spermine ratios in the erythrocyte membrane and cytosol and in blood plasma. Dietary zinc deficiency per se caused significantly (P less than 0.05) higher plasma spermidine and spermine and erythrocyte membrane spermine concentrations and significantly lower spermidine-spermine ratios in erythrocyte membrane and cytosol than in pair-fed, zinc-adequate controls.

Analysis of Variance↗
PubMed1989

Effect of zinc deficiency and food restriction in rats on erythrocyte membrane zinc, phospholipid and protein content.

Zinc deficiency in rats increases the osmotic fragility of erythrocytes, suggesting a structural defect in the plasma membrane. The purpose of this study was to determine the effect of zinc deficiency on membrane components that might be responsible for the increased fragility. Immature male rats were fed for 3 wk a zinc-deficient (0.5 mg Zn/kg) or a control (100 mg Zn/kg) diet either ad libitum or pair-fed. Red blood cell membranes were analyzed for zinc after wet ashing in nitric-perchloric acid. The fatty acid composition of membrane phosphatidylcholine and phosphatidylethanolamine was determined by gas-liquid chromatography, and the protein composition was determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The membrane zinc concentration was decreased by zinc deficiency, but returned to control levels upon repletion with a zinc-adequate diet for 3 d. The increased osmotic fragility was also restored to the control level during the same repletion period, suggesting that zinc is an important determinant of membrane stability. The phospholipid fatty acid composition was altered by zinc deficiency, but these changes were not rapidly reversed by repletion. The membrane cholesterol:phospholipid ratio was also increased by zinc deficiency. Zinc status had no influence on the membrane protein profiles of the components visualized by staining. Only the concentration of membrane zinc correlated with osmotic fragility during zinc depletion and repletion.

Analysis of Variance↗
PubMed1989

Biosynthesis of a novel form of vitamin B-6 by tumor cells.

Studies on the time-course utilization of radiolabeled pyridoxine in hepatoma-bearing rats led to the discovery of a novel vitamin B-6 product. It is present in a spectrum of tumor lines, but it is absent or occurs minimally in normal tissues. Hepatomas incorporate up to 20-30% of labeled pyridoxine into the novel species. Its structure was tentatively identified as adenosine-N6-methyl, propylthioether-N-pyridoximine-5'-phosphate. In the present study, 3B3 mouse-human hybridoma cells were incubated with radiolabeled precursor molecules, perchloric acid cell extracts were analyzed by high performance liquid chromatography (HPLC), and radioactivity in effluent fractions was measured. The results show that [G-3H]pyridoxine, [2,8-3H]adenosine, L-[35S]cysteine and L-[U-14C]serine are incorporated into the novel tumor product. These findings are interpreted to indicate that the correct structure of the novel product is adenosine-N6-diethylthioether-N'-pyridoximine-5'-phosphate. Further, these data demonstrate that tumor cells have evolved novel enzymatic steps for metabolism of vitamin B-6. The potential use of the novel metabolite as a marker for tumor genesis and establishment is especially significant, as the compound is peculiar to the neoplastic state.

Adenosine↗
PubMed1976

The zinc glycinate marker in human colon carcinoma.

In an attempt to identify new tumor markers in human colon carcinoma, we produced antisera in rabbits tolerant to normal human tissue antigens and immunized with zinc glycinate-treated extracts of liver metastases from a colon carcinoma. These antisera reacted with carcinoembryonic antigen and with an additional component present in the tumor extracts but not detected in the extracts of normal tissues. The new component, the zinc glycinate marker (ZGM), had an alpha2 mobility on immunoelectrophoresis, was soluble in 1 M perchloric acid, and had a molecular weight of approximately 2X10(6), as indicated by its elution pattern on Sepharose 6-B chromatography. It differed from alpha fetoprotein, nonspecific cross-reacting antigens (NCA, NGP, or CCA III), ferritin-like molecules, and blood group substances A, B, H, Lewis a, and Lewis b. The ZGM was similarly identified in saline or zinc glycinate extracts of 11 of 23 carcinomas of the colon. With routine hematoxylineosin staining, no histologic differences were apparent between tumors bearing the antigen and those without it.

Antigens, Neoplasm↗
PubMed1980

Detection of new cross-reacting carcinoembryonic antigen(s) on cultured tumor cells by mixed hemadsorption assay.

Antisera highly specific for carcinoembryonic antigen (CEA) from New Zealand White rabbits and a goat reacted strongly in antibody binding tests with cultured tumor cell lines, irrespective of the ability of the cell lines to produce CEA. The most reactive were colon carcinoma and melanoma cell lines, the former known to produce CEA and the latter not associated with CEA production. The reactivity was not diminished by absorption with perchloric acid extracts of normal lung or spleen, whereas absoprtion with purified CEA preparations abolished the reactivity. Quantitative absorption studies indicated that reactivity against CEA-producing cell lines could be totally removed by absorption with other CEA-producing lines but not with melanoma cell lines. Reactivity against melanoma cell lines could be completely removed by colon carcinoma cells as well as by melanoma cells. Antisera raised against purified CEA, after absorption with extracts of normal lung, still contained two populations of antibodies, one that binds a newly described antigen cross-reacting with CEA which is present on melanoma cells.

Animals↗
PubMed1981

Histone H5 in the immature blood cells of chickens with leukosis induced by avian leukosis virus strain E26.

Whole histone was isolated from the immature cells of the peripheral blood of White Leghorn chickens, line 151, with leukosis experimentally induced by avian leukosis virus, strain E26 (ALV-E26). Histone H5 was demonstrated in all samples of these cells and was characterized by electrophoresis in polyacrylamide gel, extraction with perchloric acid, amino acid analysis, and immunodiffusion in agarose gel. Histone H5 was not detected in the myeloblasts of chickens with myeloblastosis caused by the avian myeloblastosis virus. It was concluded that the immature cells (IBC-E26) obtained from the peripheral blood of chickens responding positively to ALV-E26 belonged to the erythroid blood cell series and that ALV-E26 induced in vivo erythroblastosis but not myeloblastosis in chickens. The relative amount of histone H5 in IBC-E26 was two times higher than that in the erythroblasts obtained from the peripheral blood of chickens with erythroblastosis caused by avian erythroblastosis virus, strain R of Engelbreth-Holm. Thus the erythroblasts in the circulating blood of chickens with leukosis induced by ALV-E26 seemed to be more differentiated.

Alpharetrovirus↗
PubMed1995

The ribonuclease activity of nucleolar protein B23.

Protein B23 is an abundant nucleolar protein and putative ribosome assembly factor. The protein was analyzed for ribonuclease activity using RNA-embedded gels and perchloric acid precipitation assays. Three purified bacterially expressed forms of the protein, B23.1, B23.2 and an N-terminal polyhistidine tagged B23.1 as well as the natural protein were found to have ribonuclease activity. However, the specific activity of recombinant B23.1 was approximately 5-fold greater than that of recombinant B23.2. The activity was insensitive to human placental ribonuclease inhibitor, but was inhibited by calf thymus DNA in a dose dependent manner. The enzyme exhibited activity over a broad range of pH with an apparent optimum at pH 7.5. The activity was stimulated by but not dependent on the presence of low concentrations of Ca2+, Mg2+ or NaCl. The Ca2+ effect was saturable and only stimulatory in nature. In contrast, Mg2+ and NaCl exhibited optimal concentrations for stimulation and both inhibited the ribonuclease at concentrations above these optima. These data suggest that protein B23 has intrinsic ribonuclease activity. The location of protein B23 in subcompartments of the nucleolus that contain preribosomal RNA suggests that its ribonuclease activity plays a role in the processing of preribosomal RNA.

Animals↗