Effect of low fibrinogen concentrations on the rheology of human blood in vitro

1979 ◽  
Vol 236 (3) ◽  
pp. H447-H450
Author(s):  
W. Blattler ◽  
P. W. Straub ◽  
C. Jeanneret ◽  
G. S. Horak
Keyword(s):  
Human Blood ◽  
Cell Aggregation ◽  
Fibrinogen Concentration ◽  
Shear Rates ◽  
Red Blood Cell Aggregation ◽  
Low Concentrations ◽  
Normal Human ◽  
High Concentrations

The influence of low concentrations of fibrinogen on the rheology of normal human blood was investigated with an instrument that permitted simultaneous determination of viscosity and the state of red blood cell aggregation and deformation. Fibrinogen, in concentrations of 9-82 mg/100 ml, decreased blood viscosity at all shear rates below the value obtained with red blood cells suspended in serum. At concentrations above 116 mg/100 ml viscosity was increased. Aggregate formation increased progressively as the fibrinogen concentration increased, necessitating higher dispersing shear rates. The deformation and alignment of the red cells, occurring at a shear rate of 230 s-1, was facilitated by low concentrations. The effect of fibrinogen on low-shear viscosity is explained by the formation of different kinds of aggregates. At low concentrations, the aggregates consist of only few cells forming spherelike particles displaying hemodynamic properties better than those of the single discoid cells. At normal or high concentrations big rodlike aggregates occur and increase resistance to flow.

In Vitro Effects of Ethanol on Rabbit Platelet Aggregation, Secretion of Granule Contents, and Cyclic AMP Levels in the Presence of Prostacyclin

1989 ◽  
Vol 61 (02) ◽  
pp. 254-258 ◽  
Author(s):  
Margaret L Rand ◽  
Peter L Gross ◽  
Donna M Jakowec ◽  
Marian A Packham ◽  
J Fraser Mustard
Keyword(s):  
Cyclic Amp ◽  
Inhibitory Effect ◽  
Rabbit Platelet ◽  
Inhibitory Effects ◽  
Low Concentrations ◽  
Rabbit Platelets ◽  
High Concentrations ◽  
In Vitro Effects ◽  
Aggregation Of Platelets

SummaryEthanol, at physiologically tolerable concentrations, inhibits platelet responses to low concentrations of collagen or thrombin, but does not inhibit responses of washed rabbit platelets stimulated with high concentrations of ADP, collagen, or thrombin. However, when platelet responses to high concentrations of collagen or thrombin had been partially inhibited by prostacyclin (PGI2), ethanol had additional inhibitory effects on aggregation and secretion. These effects were also observed with aspirin- treated platelets stimulated with thrombin. Ethanol had no further inhibitory effect on aggregation of platelets stimulated with ADP, or the combination of ADP and epinephrine. Thus, the inhibitory effects of ethanol on platelet responses in the presence of PGI2 were very similar to its inhibitory effects in the absence of PGI2, when platelets were stimulated with lower concentrations of collagen or thrombin. Ethanol did not appear to exert its inhibitory effects by increasing cyclic AMP above basal levels and the additional inhibitory effects of ethanol in the presence of PGI2 did not appear to be brought about by further increases in platelet cyclic AMP levels.

Aggregation of Cat Platelets in Vitro

1970 ◽  
Vol 23 (03) ◽  
pp. 601-620 ◽  
Author(s):  
Th. B Tschopp
Keyword(s):  
Adenosine Monophosphate ◽  
Blood Collection ◽  
Base Line ◽  
Reversible Aggregation ◽  
Low Concentrations ◽  
Irreversible Aggregation ◽  
High Concentrations ◽  
Two Phases ◽  
Improved Technique

SummaryAggregation of cat platelets in the citrated plasma is examined by means of Born’s absorptiometer. A marked tendency of the platelets of this species to spontaneous aggregation necessitated first of all the development of an improved technique of blood collection.A hypothesis according to which 5-HT is released from the platelets, explains the absence of oscillations on the base line of the absorptiometer, the absence of platelet swelling, when ADP is added, and the effect of stirring on the aggregation curves in cat PRP. The average volume of cat platelets amounts to 10.46 μ3 when directly fixed in the blood, when fixed from PRP to 12.17 μ3, when fixed from stirred PRP to 13.51 μ3.In low concentrations (0.3-2 μM) ADP produce reversible aggregation; in narrowly restricted, individually dissimilar mean concentrations irreversible aggregation in two phases and in high concentrations, irreversible aggregation in one phase. Like ADP serotonin produces 2 phase irreversible aggregation in concentrations of 3-10 μM, but unlike ADP, the aggregation velocity decreases again with high 5-HT concentrations (>100 μM). Adrenaline does not produce aggregation and it is likely that adenosine and adenosine monophosphate inhibit the aggregation by serotonin but not by ADP. Species differences in the aggregation of human, rabbit and cat platelets are discussed.

scholarly journals The Double Face of Ketamine—The Possibility of Its Identification in Blood and Beverages

Molecules ◽  
2021 ◽  
Vol 26 (4) ◽  
pp. 813
Author(s):  
Magdalena Świądro ◽  
Paweł Stelmaszczyk ◽  
Irena Lenart ◽  
Renata Wietecha-Posłuszny
Keyword(s):  
Date Rape ◽  
Signal To Noise Ratio ◽  
High Sensitivity ◽  
Heroin Addiction ◽  
Assisted Extraction ◽  
Low Concentrations ◽  
High Concentrations ◽  
Rosé Wine ◽  
Tof Ms

The purpose of this study was to develop and validate a high-sensitivity methodology for identifying one of the most used drugs—ketamine. Ketamine is used medicinally to treat depression, alcoholism, and heroin addiction. Moreover, ketamine is the main ingredient used in so-called “date-rape” pills (DRP). This study presents a novel methodology for the simultaneous determination of ketamine based on the Dried Blood Spot (DBS) method, in combination with capillary electrophoresis coupled with a mass spectrometer (CE-TOF-MS). Then, 6-mm circles were punched out from DBS collected on Whatman DMPK-C paper and extracted using microwave-assisted extraction (MAE). The assay was linear in the range of 25–300 ng/mL. Values of limits of detection (LOD = 6.0 ng/mL) and quantification (LOQ = 19.8 ng/mL) were determined based on the signal to noise ratio. Intra-day precision at each determined concentration level was in the range of 6.1–11.1%, and inter-day between 7.9–13.1%. The obtained precision was under 15.0% (for medium and high concentrations) and lower than 20.0% (for low concentrations), which are in accordance with acceptance criteria. Therefore, the DBS/MAE/CE-TOF-MS method was successfully checked for analysis of ketamine in matrices other than blood, i.e., rose wine and orange juice. Moreover, it is possible to identify ketamine in the presence of flunitrazepam, which is the other most popular ingredient used in DRP. Based on this information, the selectivity of the proposed methodology for identifying ketamine in the presence of other components of rape pills was checked.

An evaluation of potential seed treatments to control Fusarium solani f.sp. phaseoli, the cause of foot and root rot of Phaseolus vulgaris

1977 ◽  
Vol 89 (1) ◽  
pp. 235-238 ◽  
Author(s):  
P. E. Russell ◽  
A. E. A. Mussa
Keyword(s):  
Phaseolus Vulgaris ◽  
Fusarium Solani ◽  
Root Rot ◽  
Similar Pattern ◽  
Fungal Growth ◽  
Systemic Fungicide ◽  
Product Concentration ◽  
Low Concentrations ◽  
High Concentrations

SummaryTwo systemic fungicides, benomyl and thiabendazole, were more active than the non-systemic fungicide Drazoxolon in inhibiting fungal growth in vitro. A similar pattern was obtained in glasshouse trials with benomyl and thiabendazole giving adequate protection at low concentrations while Drazoxolon was ineffective unless applied at 50% the commercial product concentration. A field trial using thiabendazole, Drazoxolon and a mixture of benomyl and thiram confirmed the glasshouse results.Some phytotoxicity was noticed with high concentrations of both benomyl and thiabendazole, but satisfactory disease control was achieved using fungicide concentrations which did not induce phytotoxicity.

scholarly journals Colchicine-binding protein of the liver. Its characterization and relation to microtubules.

1975 ◽  
Vol 66 (3) ◽  
pp. 609-620 ◽  
Author(s):  
C Patzelt ◽  
A Singh ◽  
Y L Marchand ◽  
L Orci ◽  
B Jeanrenaud
Keyword(s):  
High Speed ◽  
Specific Binding ◽  
Electrophoretic Analysis ◽  
Binding Activity ◽  
Low Concentrations ◽  
Electrophoretic Behavior ◽  
High Affinity Binding Site ◽  
High Concentrations

Colchicine-binding activity of mouse liver high-speed supernate has been investigated. It has been found to be time and temperature dependent. Two binding activities with different affinities for colchicine seem to be present in this high-speed supernate, of which only the high-affinity binding site (half maximal binding at 5 x 10(-6) M colchicine) can be attributed to microtubular protein by comparison with purified tubulin. Vinblastine interacted with this binding activity by precipitating it when used at high concentrations (2 x 10(-3) M), and by stabilizing it at low concentrations (10(-5) M). Lumicolchicine was found not to compete with colchicine. The colchicine-binding activity was purified from liver and compared with that of microtubular protein from brain. The specific binding activity of the resulting preparation, its electrophoretic behavior, and the electron microscope appearance of the paracrystals obtained upon its precipitation with vinblastine permitted its identification as microtubular protein (tubulin). Electrophoretic analysis of the proteins from liver supernate that were precipitated by vinblastine indicated that this drug was not specific for liver tubulin. Preincubation of liver supernate with 5 mM EGTA resulted in a time-dependent decrease of colchicine-binding activity, which was partly reversed by the addition of Ca++. However, an in vitro formation of microtubules upon lowering the Ca++ concentration could not be detected. Finally, a method was developed enabling that portion of microtubular protein which was present as free tubulin to be measured and to be compared with the total amount of this protein in the tissue. This procedure permitted demonstration of the fact that, under normal conditions, only about 40% of the tubulin of the liver was assemled as microtubules. It is suggested that, in the liver, rapid polymerization and depolymerization of microtubules occur and may be an important facet of the functional role of the microtubular system.

Effects of endogenous calcium transport inhibitor from heart muscle on the active calcium uptake and passive calcium release properties of sarcoplasmic reticulum

1989 ◽  
Vol 67 (9) ◽  
pp. 999-1006 ◽  
Author(s):  
Njanoor Narayanan ◽  
Philip Bedard ◽  
Trilochan S. Waraich
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Heart Muscle ◽  
Calcium Release ◽  
Membrane Vesicles ◽  
Transport Inhibitor ◽  
Low Concentrations ◽  
Active Calcium ◽  
High Concentrations ◽  
Stimulation Of

In the present study, the effects of the cytosolic Ca2+ transport inhibitor on ATP-dependent Ca2+ uptake by, and unidirectional passive Ca2+ release from, sarcoplassmic reticulum enriched membrane vesicles were examined in parallel experiments to determine whether inhibitor-mediated enhancement in Ca2+ efflux contributes to inhibition of net Ca2+ uptake. When assays were performed at pH 6.8 in the presence of oxalate, low concentrations (<100 μg/mL) of the inhibitor caused substantial inhibition of Ca2+ uptake by SR (28–50%). At this pH, low concentrations of the inhibitor did not cause enhancement of passive Ca2+ release from actively Ca2+-loaded sarcoplasmic reticulum. Under these conditions, high concentrations (>100 μg/mL) of the inhibitor caused stimulation of passive Ca2+ release but to a much lesser extent when compared with the extent of inhibition of active Ca2+ uptake (i.e., twofold greater inhibition of Ca2+ uptake than stimulation of Ca2+ release). When Ca2+ uptake and release assays were carried out at pH 7.4, the Ca2+ release promoting action of the inhibitor became more pronounced, such that the magnitude of enhancement in Ca2+ release at varying concentrations of the inhibitor (20–200 μg/mL) was not markedly different from the magnitude of inhibition of Ca2+ uptake. In the absence of oxalate in the assay medium, inhibition of Ca2+ uptake was observed at alkaline but not acidic pH. These findings imply that the inhibition of Ca2+ uptake observed at pH 6.8 is mainly due to decrease in the rate of active Ca2+ transport into the membrane vesicles rather than stimulation of passive Ca2+ efflux; at alkaline pH (pH 7.4), enhanced Ca2+ efflux contributes substantially, if not exclusively, to the decrease in Ca2+ uptake observed in the presence of the inhibitor. It is suggested that if the cytosolic inhibitor has actions similar to those observed in vitro in intact cardiac muscle, acid–base status of the intracellular fluid would be a major factor influencing the nature of its effects (inhibition of Ca2+ uptake or stimulation of Ca2+ release) on transmembrane Ca2+ fluxes across the sarcoplasmic reticulum.Key words: sarcoplasmic reticulum, Ca2+ uptake, Ca2+ release, endogenous inhibitor, heart muscle.

scholarly journals Hypogonadism associated withCyp19a1 (Aromatase) post-transcriptional upregulation inCelf1-KO mice

2015 ◽  
pp. MCB.00074-15 ◽  
Author(s):  
Gaella Boulanger ◽  
Marie Cibois ◽  
Justine Viet ◽  
Alexis Fostier ◽  
Stéphane Deschamps ◽  
...  
Keyword(s):  
Rna Binding ◽  
Hypogonadotropic Hypogonadism ◽  
Type I ◽  
Male Gametes ◽  
Low Concentrations ◽  
Reporter Assays ◽  
High Concentrations ◽  
In Vitro Interaction

CELF1 is a multifunctional RNA-binding protein that controls several aspects of RNA fate. The targeted disruption of theCelf1gene in mice causes male infertility due to impaired spermiogenesis, the post-meiotic differentiation of male gametes. Here, we investigated the molecular reasons that underlie this testicular phenotype. By measuring sex hormone levels, we detected low concentrations of testosterone inCelf1-null mice. We investigated the effect ofCelf1disruption on the expression levels of steroidogenic enzyme genes, and we observed thatCyp19a1was upregulated.Cyp19a1encodes aromatase, which transforms testosterone into estradiol. Administration of testosterone or the aromatase inhibitor Letrozole partly rescued the spermiogenesis defects, indicating that a lack of testosterone associated with excessive aromatase contributes to the testicular phenotype. In vivo and in vitro interaction assays demonstrated that CELF1 binds toCyp19a1mRNA, and reporter assays supported the conclusion that CELF1 directly repressesCyp19a1translation. We conclude that CELF1 downregulatesCyp19a1/Aromatasepost-transcriptionally to achieve high concentrations of testosterone compatible with spermiogenesis completion. We discuss the implications of these findings with respect to reproductive defects in men, including patients suffering from isolated hypogonadotropic hypogonadism and myotonic dystrophy type I.

Effects of polymethoxylated flavone metabolites on apoB100 secretion and MTP activity in Huh7.5 cells

2021 ◽  
Vol 18 ◽  
Author(s):  
Danielle R. Gonçalves ◽  
Thais B. Cesar ◽  
John A. Manthey ◽  
Paulo I. Costa
Keyword(s):  
Lipid Synthesis ◽  
Dependent Manner ◽  
Transfer Protein ◽  
Low Concentrations ◽  
Wide Range ◽  
Cell Assays ◽  
Polymethoxylated Flavones ◽  
High Concentrations

Background: Citrus polymethoxylated flavones (PMFs) reduce the synthesis of liver lipoproteins in animal and in vitro cell assays, but few studies have evaluated the direct effects of their metabolites on this highly regulated process. Objective: To investigate the effects of representative metabolites of PMF on the secretion of liver lipoproteins using the mammalian cell Huh7.5. Method: In this study, the influences of three PMFs and five previously isolated PMF metabolites on hepatic apoB-100 secretion and microsomal transfer protein (MTP) activity were evaluated. Tangeretin (TAN), nobiletin (NOB) and 3,5,6,7,8,3′,4′-heptamethoxyflavone (HMF), and their glucuronides (TAN-Gluc, NOB-Gluc and HMF-Gluc) and oxidatively demethylated metabolites (TAN-OH, NOB-OH, HMF-OH) were incubated with Huh7.5 cells to measure their inhibitory effects on lipid synthesis. Results: The results showed that TAN, HMF and TAN-OH reduced the secretion of apoB-100 in a dose-dependent manner, while NOB and the other tested metabolites showed no inhibition. MTP activity in the Huh7.5 cells was significantly reduced in the presence of low concentrations of TAN, and in high concentrations of NOB-OH. This study also showed that PMFs and PMF metabolites produced a wide range of effects on apoB-100 secretion and MTP activity. Conclusion: The results suggest that while PMFs and their metabolites control dyslipidemia in vivo, the inhibition of MTP activity cannot be the only pathway influenced by these compounds.

Manometric and Electrode-Probe Determination of CO2 in Fish Flesh

1982 ◽  
Vol 45 (10) ◽  
pp. 932-934 ◽  
Author(s):  
JIM W. CONRAD ◽  
GLENN C. ROBERTS ◽  
HAROLD J. BARNETT
Keyword(s):  
Mean Difference ◽  
Fish Products ◽  
Probe Technique ◽  
Fish Flesh ◽  
Ion Probe ◽  
Low Concentrations ◽  
Manometric Method ◽  
High Concentrations ◽  
Manometric Technique

A rapid electrometric method for determining endogenous and added CO2 in fish products was studied using an Orion CO2 probe and Orion ionalyzer model #801. Analytical results were compared to those using the standard Warburg manometric technique. Comparisons showed a ± 20.8% mean difference for low concentrations of CO2 (&lt;350 ppm) and a ± 10.7% mean difference for high concentrations of CO2 (&gt;800 ppm). The probe technique was found to be easier to use and required less time for operating and cleanup procedures than the manometric method. Based on recovery studies, the specific ion probe was more accurate at all levels of CO2 evaluated than the manometric device.

Ticlopidine Selectively Inhibits Human Platelet Responses to Adenosine Diphosphate

1991 ◽  
Vol 66 (06) ◽  
pp. 694-699 ◽  
Author(s):  
Marco Cattaneo ◽  
Benjaporn Akkawat ◽  
Anna Lecchi ◽  
Claudio Cimminiello ◽  
Anna M Capitanio ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Adenosine Diphosphate ◽  
Inhibitory Effect ◽  
Clot Retraction ◽  
Fibrinogen Binding ◽  
Low Concentrations ◽  
Binding Inhibition ◽  
High Concentrations ◽  
Formalin Fixed

SummaryPlatelet aggregation and fibrinogen binding were studied in 15 individuals before and 7 days after the oral administration of ticlopidine (250 mg b.i.d.). Ticlopidine significantly inhibited platelet aggregation induced by adenosine diphosphate (ADP), the endoperoxide analogue U46619, collagen or low concentrations of thrombin, but did not inhibit platelet aggregation induced by epinephrine or high concentrations of thrombin. Ticlopidine inhibited 125I-fibrinogen binding induced by ADP, U46619 or thrombin (1 U/ml). The ADP scavengers apyrase or CP/CPK, added in vitro to platelet suspensions obtained before ticlopidine, caused the same pattern of aggregation and 125I-fibrihogen binding inhibition as did ticlopidine. Ticlopidine did not inhibit further platelet aggregation and 125I-fibrinogen binding induced in the presence of ADP scavengers. After ticlopidine administration, thrombin or U46619, but not ADP, increased the binding rate of the anti-GPIIb/IIIa monoclonal antibody 7E3 to platelets. Ticlopidine inhibited clot retraction induced by reptilase plus ADP, but not that induced by thrombin or by reptilase plus epinephrine, and prevented the inhibitory effect of ADP, but not that of epinephrine, on the PGE1-induced increase in platelet cyclic AMP. The number of high- and low-affinity binding sites for 3H-ADP on formalin-fixed platelets and their K d were not modified by ticlopidine. These findings indicate that ticlopidine selectively inhibits platelet responses to ADP.

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