Platelet function and simultaneous thrombelastograms from whole blood and plasma

The prognosis of cholesterol embolism is often poor, and no treatment is presently available. We report the use of a stable prostacyclin analogue in treating cholesterol embolism in a diabetic patient with arteriopathy. As a sole therapy, it improved cutaneous manifestations and pain, in parallel with an increased transcutaneous oxymetry. We think that prostacyclin analogues are novel candidates for the treatment of cholesterol embolism.     

Effect of supplementation with selenium on whole blood glutathione peroxidase activities and on plasma and tissue selenium concentrations in lambs

In recent years the selenium (Se) intake of the human population of the UK has shown a marked decline from 60 micrograms/d in 1978 to around 30 micrograms/d in 1990 owing largely to a significant reduction in the importation of North American wheat for bread-making flour. Other countries (Finland, for example) in similar situations have instituted fertilization programs in order to raise cereal Se concentrations and thus boost dietary intakes. An alternative approach would be to increase the Se concentration of carcass meat by supplementation of meat animals for a limited period prior to slaughter. A trial was set up with store lambs to evaluate this approach. Sixteen Scottish Blackface lambs were stratified according to live weight and then randomly allocated to one of four treatments: unsupplemented, or 3.5, 7, or 10.5 mg Se/head/wk. After 14 wk, the lambs were sacrificed and samples of shoulder and thigh muscle, liver, and kidney were obtained for analysis. All three treatments effected an increase in whole blood glutathione peroxidase (GSH-Px) and plasma Se concentrations over controls. Shoulder, thigh, and liver Se exhibited a dose-response relationship to treatment, but kidney Se concentrations were unaffected by treatment. Muscle and some organ meat Se concentrations can therefore be increased by supplementation and could contribute to increased human dietary intakes of the element.     

Comparison of 5-fluorouracil pharmacokinetics in whole blood, plasma, and red blood cells in patients with colorectal cancer

STUDY OBJECTIVE: To compare 5-fluorouracil (5-FU) pharmacokinetics in whole blood, plasma, and red blood cells in patients with colorectal cancer. DESIGN: Prospective, unblinded observational study in consecutive patients. SETTING: Large regional teaching hospital. PATIENTS: Five patients with colorectal cancer. INTERVENTIONS: Patients received folinic acid 200 mg/m2 intravenously over 2 hours, followed by 5-FU 600 mg/m2 intravenous bolus over 30 minutes, then 5-FU 600 mg/m2 intravenous infusion over 22 hours, administered on days 1 and 2. This 48-hour cycle was repeated every 14 days. MEASUREMENTS AND MAIN RESULTS: Concentrations of 5-FU in whole blood, plasma, and red blood cells were determined by high-performance liquid chromatography. ADAPT II was used for pharmacokinetic computations. The optimum model was determined for each matrix by calculating Akaike's information criteria values. Concentrations of 5-FU in whole blood were 106-115% of simultaneous plasma concentrations (median 112%), and packed red blood cell levels were 5-17% of plasma concentrations (median 11%). The drug's concentration-time profile was similar in the three matrices. The drug is reported to be unstable in whole blood, and red blood cell 5-FU concentrations were near the limit of detection (10 ng/ml), supporting plasma as the preferred matrix for therapeutic drug monitoring studies. Six pharmacokinetic models were fitted to the 5-FU individual data sets to determine the best curve fit. The optimal model for whole blood and plasma data sets was one compartment with both linear and nonlinear elimination models; a one-compartment model with nonlinear elimination provided the best curve fit for 5-FU in red blood cells. A two-compartment model with nonlinear elimination gave a similar degree of curve fit for plasma 5-FU as the one-compartment model with both linear and nonlinear elimination. CONCLUSIONS: These pharmacokinetic results provide the basis for further investigation into the ability to correlate 5-FU systemic exposure with clinical drug activity.     

1H NMR of albumin in human blood plasma: drug binding and redox reactions at Cys34

1H NMR methods are described which allow direct studies of the Cys34 binding site of albumin in intact human blood plasma in vitro. Antiarthritic gold drugs and the alcohol-aversive drug disulfiram induce a structural transition detectable via H epsilon 1 and H delta 2 resonances of His3 of albumin, and reactions of cystine, glutathione and captopril in plasma have also been investigated. Contrary to most assumptions, little of the albumin in normal plasma appears to be blocked at Cys34 as a cystine disulfide.     

Mutagenic and genotoxic activities of four pesticides: captan, foltaf, phosphamidon and furadan

The mutagenic and genotoxic potential of four pesticides viz. captan, foltaf, phosphamidon and furadan was evaluated by the Ames mutagenicity assay and their DNA damaging ability on radiation repair defective E. coli K-12 strains respectively. The mutagenic spectrum revealed captan to be most mutagenic in the absence of metabolic activation, while the presence of S9 mix led to an attenuated mutagenic response. Foltaf, phosphamidon and furadan were detected as relatively weaker mutagens. A significant decrease in the survival of SOS defective mutants, recA, lexA and pol- of E. coli was observed as compared to their wild-type counterparts in the presence of the pesticides. The role of SOS repair genes gains further support from the Salmonella strains triggering the error-prone SOS response.     

Amyloid beta-peptide is transported on lipoproteins and albumin in human plasma

The amyloid beta-peptide (Abeta) is the major constituent of neuritic plaques in Alzheimer's disease and occurs as a soluble 40-42-residue peptide in cerebrospinal fluid and blood of both normal and AD subjects. It is unclear whether Abeta, once it is secreted by cells, remains free in biological fluids or is associated with other proteins and thus transported and metabolized with them. Such knowledge of the normal fate of Abeta is a prerequisite for understanding the changes that may lead to the pathological aggregation of soluble Abeta in vivo, the possible influence of certain extracellular proteins, particularly apolipoprotein E, on plaque formation, and the pharmacology of putative Abeta-lowering drugs. To address the question of Abeta distribution in human biological fluids, we incubated fresh human plasma from 38 subjects with physiological concentrations (0.5-0.7 nM) of radioiodinated Abeta1-40 and seven plasma samples with Abeta1-42. Lipoproteins and lipid-free proteins were separated and analyzed for bound iodinated Abeta1-40. We found that up to 5% of Abeta added to plasma is bound to selected lipoproteins: very low density, low density, and high density, but not lipoprotein(a). The large majority ( approximately 89%), however, is bound to albumin, and very little Abeta is free. Abeta distribution in plasma was not significantly influenced by apolipoprotein E genotype. We conclude that Abeta is normally bound to and transported by albumin and specific lipoproteins in human plasma under physiological conditions.     

Determination of propofol in rat whole blood and plasma by high-performance liquid chromatography

A simple, accurate and sensitive high-performance liquid chromatographic method was developed for the determination of propofol, an intravenous anaesthetic agent, in rat whole blood or plasma samples. The method is based on precipitation of the protein in the biological fluid sample and direct injection of the supernatant into an HPLC system involving a C18 reversed-phase column using a methanol-water (70:30) mobile phase delivered at 1 ml/min. Propofol and the internal standard (4-tert.-octylphenol) were quantified using a fluorescence detector set at 276 nm (excitation) and 310 nm (emission). The analyte and internal standard had retention times of 6.3 and 10.5 min, respectively. The limit of quantification for propofol was 50 ng/ml using 100 microl of whole blood or plasma sample. Calibration curves were linear (r2=0.99) over a 1-10 microg/ml concentration range and intra- and inter-day precision were between 4-11%. The assay was applied to the determination of propofol whole blood pharmacokinetics and propofol whole blood to plasma distribution ratios in rats.     

Processing of adenosine receptor agonists in rat and human whole blood

A stability study of adenosine receptor agonists in rat and human whole blood was performed. The compounds were incubated at 37 degrees in fresh blood, and aliquots of the incubation mixture were hemolyzed at regular time intervals and analyzed with HPLC. N6-cyclopentyladenosine (CPA) and N6-cyclobutyladenosine (CBA) were degraded, whereas N6-cyclohexyladenosine, N6-cycloheptyladenosine and N6-sulfophenyladenosine were not. 2-Chloroadenosine had a half-life very similar to that of CPA. However, the 2'-, 3'-, and 5'-deoxyribose derivatives of CPA remained intact. The nucleoside transport inhibitor nitrobenzylthioinosine attenuated CBA and CPA metabolism in rat blood as did the inhibitor of adenosine deaminase erythro-9-(2-hydroxy-3-nonyl)adenine, albeit at relatively high concentrations. Complete blockade of CBA and CPA degradation was achieved by a preincubation of rat and human blood with the adenosine kinase (AK) inhibitor 5'-amino-5'-deoxyadenosine. We conclude that the two adenosine analogues are metabolized by AK both in rat and in human whole blood.     

Biodistribution of, antimutagenic efficacies in Salmonella typhimurium of, and inhibition of P450 activities by ellagic acid and one analogue

Ellagic acid (EA) is generated by hydrolysis of ellagitannins present in fruit berries and edible nuts and grapes. Large doses of EA prevent lung tumorigenesis induced by the tobacco carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) in A/J mice. In this study, we document the efficacies of the EA structural analogue (3,4,7,8-tetrahydroxy-6H-benzo[b,d]pyran-6-one) (analogue 1) to inhibit specific P450 activities, pulmonary metabolism of NNK in A/J mice, and NNK-induced mutations in Salmonella typhimurium. Mouse lung microsomes metabolized benzyloxyresorufin, a marker of cytochrome P450 2B1 activity, more extensively than methoxyresorufin or ethoxyresorufin. The EA analogue was more effective than EA in inhibiting dealkylation of the three alkoxyresorufins, suggesting that it is a nonspecific inhibitor of P450s. Mouse lung microsomes hydroxylate testosterone in the 7alpha and 6beta positions, suggesting contributions of P450 2A1 and P450 3A2 isozymes, respectively. Inhibition of both pathways was more effective with the EA analogue than with EA. Mouse lung explants metabolized NNK by alpha-carbon hydroxylation (activation) and pyridine N-oxidation (deactivation). Both pathways were inhibited when 100 microM EA was added to the culture medium. The EA analogue was a better inhibitor of the activation of NNK to electrophilic species than EA. Mouse lung microsomes activate NNK to intermediates mutagenic to S. typhimurium. Inhibition of NNK mutagenicity by EA or the EA analogue was 20 or 65%, respectively. The distribution of the EA analogue in lung and liver was determined following gavage with 1.7 mmol of the EA analogue. In the lung, a maximal level of EA analogue corresponding to 105 nmol was observed 30 min after administration of the analogue. The level in liver tissues was 4-fold lower than in the lung. Results of this study demonstrate that the EA analogue is more effective than EA in inhibiting the pulmonary activation of NNK and suggest that the EA analogue could be effective in preventing lung tumorigenesis.     

Fatty acid composition of the lipids in human blood plasma and erythrocyte membranes during simulation of extravehicular activities of cosmonauts

Dynamics of the lipoacidic content of total plasma lipids and erythtocyte membranes was studied in 32 experiments with ten apparently healthy male subjects aged 27 to 41 years who were exposed to repeated decompression from the normal ground down to 40-35 kPa. For two hours of exposure to lowered pressure the subjects were breathing pure oxygen in mask and performing incremental physical work mimicking loading of the upper extremities of cosmonauts doing extravehicular activities (EVA) at the energy cost of 3 kcal/min. Decompression sessions were repeated with intervals from 3 to 5 days. In seven experiments, the subjects developed symptoms of the decompression sickness (DCS). Penetration of gas bubbles (GB) into the pulmonary artery was registered in 27 cases (84.4%). In 24 cases maximal intensity of the US signals from GB reached 3 to 4 Spencer's points. No changes in the lipidoacidic content of blood plasma or erythrocyte membranes were determined following the first exposure to decompression. BY the onset of repeated decompression, total number of lipids in erythrocyte membranes decreased from 54.6 to 40.4 mg% in the group of subjects who had not displayed DCS symptoms (n = 5) and from 51.2 to 35.2 mg% (p < 0.05) in the group of subjects with DCS symptoms (n = 5). In the subjects with DCS, polyunsaturated linoleic acid (18:2) tended to decrease against the upward trend of saturated fatty acids (16:0, 18:0). In these subjects, arachidonic acid in erythrocyte membranes (20:4) decreased following each decompression exposure and significantly increased (p < 0.05) in-between. In both groups, blood plasma showed slight fluctuations in the lipoacidic contents. These data suggest that exposure to the variety of the EVA-simulating factors may entail quite distinct but reversible modifications in the lipid metabolism in blood and the structural/functional state of erythrocyte membranes. The most marked alterations were observed in the subjects with the DCS symptoms during high intensity of US signals from GB in the venous blood flow.     

Simultaneous automated determination of glucose 6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase activities in whole blood

We have shown previously that the non-steroidal anti-inflammatory drug flufenamate (FFA) causes a maintained increase in [Ca2+]i and transient increases in a Ca(2+)-activated nonselective cation current (ICAN) and a Ca(2+)-activated slow, outward Cl- current (lo-slow) in molluscan neurons [Shaw T., Lee R.J., Partridge L.D. Action of diphenylamine carboxylate derivatives, a family of non-steroidal anti-inflammatory drugs, on [Ca2+]i and Ca(2+)-activated channels in neurons. Neurosci Lett 1995; 190:121-124]. Here we demonstrate that pretreatment of neurons with 10 microM thapsigargin eliminates the FFA-induced increase in [Ca2+]i and substantially reduces both ICAN and Io-slow supporting the hypothesis that the FFA-induced increase in [Ca2+]i results primarily from Ca2+ release from a thapsigargin-sensitive intracellular store. The [Ca2+]i response appears to be sustained, not by influx of extracellular Ca2+, but by inhibitory effects of FFA on Ca2+ removal from the cytosol. Inhibition of Ca2+ efflux may be an important component of the FFA-induced activation of both ICAN and Io-slow, as Ca2+ release by thapsigargin alone is not sufficient to activate either current. Our data also demonstrate that the effects of FFA on [Ca2+]i, ICAN and Io-slow are reversible and suggest that protein phosphorylation as well as an increase in [Ca2+]i are involved in the FFA-induced activation of Io-slow. Effects on neuronal Ca2+ handling as well as activation of ICAN or Io-slow may partially explain the analgesic effects of FFA.     

Peroxynitrite augments fMLP-stimulated chemiluminescence by neutrophils in human whole blood

The neutrophil respiratory burst was examined by the technique of luminol-dependent chemiluminescence (LDCL) triggered by submaximal concentrations of N-formyl-methionyl-leucyl-phenylalanine (fMLP) in diluted whole blood. We sought to identify the chemical species responsible for LDCL in whole blood, to examine the role of leukotriene B4 (LTB4) and other arachidonic acid metabolites as mediators of the fMLP signaling pathway, and to investigate the effect of peroxynitrite on this response. Both sodium azide and taurine significantly inhibited LDCL (93% inhibition with 100 microM azide, 52% inhibition with 10 mM taurine). More modest inhibition was seen with superoxide dismutase (SOD), catalase, the nitric oxide synthase inhibitor monomethyl-L-arginine (L-NMMA), and with inhibitors of the cyclooxygenase (indomethacin), lipoxygenase (AA-861; no effect), and cytochrome P-450 (SKF 525-A) pathways of arachidonic acid metabolism. The nitric oxide donor SIN-1 (1-100 microM) and peroxynitrite (10-300 microM) also augmented fMLP-induced LDCL. The augmentation seen with peroxynitrite and SIN-1 was attenuated by SOD. Despite the increase in LDCL, peroxynitrite caused a dose-related inhibition of fMLP-stimulated LTB4 release. In summary, our results indicate that (1) LDCL elicited by fMLP in diluted whole blood appears primarily mediated by hypochlorous acid derived from myeloperoxidase; (2) pretreatment with the nitric oxide donor SIN-1 or with peroxynitrite augments LDCL; and (3) LTB4 release does not contribute to fMLP-stimulated LDCL or in the modulation of LDCL by SIN-1 or peroxynitrite.     

Effect of whole blood storage on factor VIII recovery in fresh frozen plasma and cryoprecipitate

BACKGROUND: Evaluate two recent tests for HIV infection diagnosis using the Enzyme-Linked Fluorescent Assay (ELFA) technique for rapid diagnosis in microbiology or virology laboratories. METHODS: A panel of 429 sera with different Ab prevalencies and different sources was prepared: 50 blood bank samples from habitual donors; 8 with positive results from other blood banks; 50 from individuals infected with HIV at various stages; 164 from subjects having practices of risk, with a prevalence of 24.4%; and 157 hospital samples selected at random, with a prevalence of 12.2%. All the samples were analyzed using IMX HIV-1/HIV-2 (ELFA A) and VIDAS HIV-1+2 (ELFA B) tests. Samples yielding positive results from either of the two tests were confirmed by WB. In the cases of indeterminate WB, p24 antigenemia was detected, the positive cases being confirmed by neutralization. RESULTS: From the panel of sera studied, 112 samples were reactive by ELFA A and 109 by ELFA B. The concordance between both assays was 97.3% for reactive samples and 99.1% for non-reactive. WB confirmation showed a global sensitivity of 100% in both tests, with a specificity of 98.4% for ELFA A and 99.3% for ELFA B. Three samples positive for both tests but indeterminate for WB corresponded to sera in the seroconversion window period, one with positive p24 antigenemia. CONCLUSIONS: The new ELFA technology is shown to be an adequate rapid, automatized diagnosis method which decreases risks from laboratory manipulation, with good sensitivity and specificity characteristics for the diagnosis of Ab HIV in health care settings.     

Degradation of transferrin and albumin by radical reactions in human plasma evaluated by immunoblot

Immunoblot analysis showed that transferrin and human serum albumin were degraded in a similar rate on the basis of the protein weight by radical reactions using a solution containing each protein initiated by Cu2+ and hydrogen peroxide. When plasma was treated with Cu2+ and hydrogen peroxide, the rate profile of the degradation of transferrin was similar to that of albumin based on immunoblot analysis in spite that the content of these proteins in plasma was considerably different. These results suggest that highly reactive hydroxyl radicals attack these proteins indiscriminately. Present observations demonstrate that immunoblot analysis is an effective method to analyze radical reactions of each protein in the presence of many other proteins like plasma.     

Luminol-enhanced, whole blood chemiluminescence of human neutrophils evaluated by means of an automated, computer-assisted, and high-sensitivity luminescence analyzer

To evaluate the usefulness of two standardized commercially available amplification assays for the detection of Mycobacterium tuberculosis: Amplicor test (Roche) and MTD-Amplified direct test (Gen-Probe) a total of 281 respiratory specimens from 198 patients with symptoms of pulmonary diseases were examined and compared with conventional methods. Fifty-seven specimens were positive and 218 negative by both amplification assays. Three specimens were reactive by Amplicor only, and three by MTD only. In comparison with culture, the sensitivity, specificity, positive predictive value and negative predictive value were 96.0, 94.8, 80.0, and 99.1%, respectively, for the Amplicor test; the corresponding values were 94.0, 94.4, 78.3, and 98.6%, respectively, for the MTD. However, when 28 specimens from 14 patients on antituberculous therapy were excluded the improvement in PPV and specificity of both assays was obtained. In conclusion, both commercially available amplification tests are almost equally sensitive and specific and are suitable for the implementation in daily routine work in the specialized clinical laboratories.