Inhibition of platelet aggregation by acetylsalicylic acid and other inhibitors

Effects on platelet aggregation were examined of acetylsalicylic acid (ASA), indomethacin and a number of other agents including dipyridamole, phenylbutazone and sulfinpyrazone under standardized conditions. The Born turbidometric method of measuring platelet aggregation was used with collagen as the stimulus for aggregation. ASA and indomethacin were shown to be among the most potent inhibitors of aggregation, being active at minimal effective concentrations of 1-3 mug/ml using a 10 min time of pre-incubation with the platelet-rich plasma (degree of aggregation inhibition was time dependent). Most of the other agents tested were also active in vitro and both prostaglandin E1 and adenosine were more potent than ASA or indomethacin. However, these agents were shown not to exert significant inhibitory effects when administered orally to rats (dose 10 and 30 mg/kg). ASA proved to be effective in doses as low as 3 mg/kg, and indomethacin in doses as low as 1 mg/kg orally. The inhibitory effects of ASA on aggregation remained for several days after a single oral dose, whereas the effects of indomethacin disappeared within 24 h.     

A fifty percent reduction of platelet surface glycoprotein Ib does not affect platelet adhesion under flow conditions

Glycoprotein (GP) Ib is an adhesion receptor on the platelet surface that binds to von Willebrand Factor (vWF). vWF becomes attached to collagens and other adhesive proteins that become exposed when the vessel wall is damaged. Several investigators have shown that during cardiopulmonary bypass (CPB) surgery and also during platelet activation in vitro by thrombin or thrombin receptor activating peptide (TRAP) GPIb disappears from the platelet surface. Such a disappearance is presumed to lead to a decreased adhesive capacity. In the present study, we show that a 65% decrease in platelet surface expression of GPIb, due to stimulation of platelets in Orgaran anticoagulated whole blood with 15 micromol/L TRAP, had no effect on platelet adhesion to both collagen type III and the extracellular matrix (ECM) of human umbilical vein endothelial cells under flow conditions in a single-pass perfusion system. In contrast to adhesion, ristocetin-induced platelet agglutination was highly dependent on the presence of GPIb. Immunoelectron microscopic studies showed that GPIb almost immediately returned to the platelet surface once platelets had attached to collagen. In a subsequent series of experiments, we showed that when less than 50% of GPIb was blocked by an inhibitory monoclonal antibody against GPIb (6D1), platelet adhesion under flow conditions remained unaffected.     

Effects of three trans isomers of eicosapentaenoic acid on rat platelet aggregation and arachidonic acid metabolism

PURPOSE: To compare in a randomized, prospective manner infectious complication rates associated with presacral drainage versus no drainage in the presence of penetrating rectal injury. METHODS: During a 45-month period, 48 patients with penetrating rectal injuries were entered into a randomized, prospective study at an urban Level I trauma center. The patients were randomized to a presacral drainage group or a nondrainage group. Randomization was performed after detection of the rectal injury. Forty-four injuries were identified by proctoscopy (92%), with the rest detected intraoperatively or by physical examination. All patients with rectal injuries were included regardless of age, associated injuries, time from injury to operation, blood loss, severity of rectal injury, other abdominal organs injured, or hemodynamic stability. Rectal injuries were defined as those injuries to the large bowel distal to the peritoneal reflection. All rectal injuries underwent fecal diversion, and all drainage was accomplished using closed Jackson-Pratt drainage. RESULTS: Forty-eight patients were studied, of whom 25 were randomized to no drainage and 23 were randomized to presacral drainage. The average age for the nondrainage group was 21.9 years, and the average age for the presacral drainage group 26.0 years. The average Penetrating Abdominal Trauma Index score was 34.3 for the nondrainage group and 32.4 for the presacral drainage group. There were two (8%) septic complications (one perirectal and one perivesical abscess) associated with the rectal injuries in the presacral drainage group. The abscesses in the drainage group resolved after computed tomography-guided drainage. There was one (4%) septic complication (rectocutaneous fistula) in the nondrainage group, which was associated with a retained missile fragment. The fistula resolved after bedside percutaneous removal of the missile fragment. CONCLUSION: We conclude that presacral drainage for penetrating rectal injuries has no effect on infectious complications associated with the rectal injuries.     

Leptin does not affect adipocyte glucose metabolism: studies in fresh and cultured adipocytes

Leptin, the 16-kd hormone produced by white fat cells, regulates energy homeostasis, satiety, and multiple sites in the neuroendocrine system. Leptin receptors have been identified in the central nervous system (CNS) and are widespread in peripheral tissues, including fat. Given the association between insulin resistance and obesity, it is important to establish whether leptin has additional effects on peripheral insulin action and glucose metabolism. This study examined whether leptin has a direct autocrine/paracrine action on glucose metabolism in both freshly isolated and 24-hour cultured rat fat cells. Freshly isolated rat adipocytes were incubated for 30 minutes with 200 ng/mL recombinant murine leptin. Thereafter, basal and insulin-stimulated (10(-8) mol/L) glucose transport, glycolysis-Krebs oxidation and lipogenesis ([6-14C]glucose conversion to [14C]O2 and to [14C]triglyceride), and lipolysis were measured. Upon leptin exposure, no statistical differences were detected in glucose transport or metabolism. Increasing the leptin concentration to 1 to 2 microg/mL or prolonging the duration of preincubation with the fat cells to 60 minutes before the metabolic assays did not alter the results. Finally, using two disparate fat cell culture methods with differing substrate additions (pyruvate and high or low glucose concentrations), there was no effect of 24-hour exposure to leptin (200 ng/mL) on basal and insulin-stimulated glucose transport or lipogenesis. We conclude that leptin does not modulate basal or insulin-stimulated glucose metabolism in isolated and cultured fat cells in vitro. However, in vivo, higher pericellular leptin concentrations, as well as other cellular or soluble serum factors, may exist that might lead to a physiologically relevant autocrine action of leptin.     

Response-to-stimulus interval does not affect implicit motor sequence learning, but does affect performance

There is accumulating evidence that lateral assemblies (rafts) of sphingolipids and cholesterol form platforms that serve to support numerous cellular events in membrane traffic and signal transduction. Raft membrane microdomains are thought to function by preferentially associating with specific proteins while excluding others. The basic forces driving raft formation are lipid interactions which are, per se, weak and transient. Sphingolipid rafts should therefore be considered to be dynamic structures in which cholesterol plays an important role as a linker. Caveolins influence these dynamics by forming stabilized raft domains in intracellular membranes as well as at the plasma membrane. Recent data suggest that clustering of raft components could regulate raft dynamics and therefore represents an important feature in the function of these membrane microdomains.     

Relationships between serum lipids, platelet membrane fatty acid composition and platelet aggregation in type 2 diabetes mellitus

In order to gain further insight into the mechanism of platelet dysfunction frequently reported in diabetes we investigated circulating fatty acids, lipid composition of platelet membrane and platelet function in Type 2 diabetic patients. In these subjects, percentages of C16 : 1n-7 and C18 : 1n-9 in serum phospholipid fraction and of C16 : 1n-7 in serum cholesterol ester fraction were decreased. Moreover, the content of C20 : 4n-6 in serum cholesterol esters was altered in Type 2 diabetic subjects: C18 : 0 and C20 : 3n-6 were increased but C20 : 4n-6 content was similar to controls. Aggregation in vitro did not differ from controls but aggregation in vivo was increased in Type 2 diabetic subjects. No correlation was observed between metabolic parameters -i.e., HbA1, blood glucose, serum triglycerides and total cholesterol, circulating fatty acids and fatty acid content of platelet membrane. A negative linear correlation was found between aggregation in vivo and C20 : 4n-6 content of platelet membrane. Moreover, a U shaped relationship was observed between platelet aggregation in vitro and C20 : 4n-6 content of platelet membrane suggesting that C20 : 4n-6 level should be tightly controlled otherwise platelet hyperreactivity may occur. These results indicate that despite a normal mean C20 : 4n-6 content in the platelet membrane, regulation of C20 : 4n-6 metabolism is less strictly controlled in Type 2 diabetes mellitus and confirm the importance of arachidonic acid platelet content in the regulation of platelet aggregability.     

Inhibition of platelet aggregation by alpha1-acid glycoprotein

In view of known abnormalities of plasma proteins in diseases showing changes in platelet aggregation, the effect of one of the major serum proteins, alpha1-acid glycoprotein, on platelet aggregation was evaluated. This protein, when added to platelet-rich plasma, markedly inhibited platelet aggregation induced by both adenosine diphosphate (ADP) and epinephrine. Transferrin, similarly studied, had no effect. These results are consistent with the hypothesis that the relative concentration of alpha1-acid glycoprotein may influence platelet aggregation in diseases associated with abnormal concentrations of this protein.     

Lactic acidosis in long-chain fatty acid beta-oxidation disorders

Novel polyamides were developed that can be used as cross-linking agents for proteins such as hemoglobin. Water-soluble, nonimmunogenic polyamides containing oxygen and sulfur atoms in the backbone were prepared by the polycondensation of the diacids bis(carboxymethyloxyacetyl)-1,4-diaminobutane (1a) or 3, 3'-thiodipropionic acid (1b) with diethylene glycol bis(3-aminopropyl) ether (2). The resulting alpha,omega-diacids were converted to the corresponding activated esters using any of a variety of carboxylic acid activating reagents including the novel reagent diphenyl(1-methylimidazol-2-thiyl)phosphonate (9). The resulting polyamides could be activated with a broad spectrum of groups that allow for the cross-linking and surface modification of proteins.     

Eprosartan does not affect the pharmacodynamics of warfarin

The purpose of this study was to conduct a retrospective analysis of the clinical spectrum, treatment and morbidity of the patients who have suffered high tension electrical injuries with current passage through their body (59 patients). Voltage, localization and surgical treatment seem to be the main factors influencing the lesion and the morbidity. The following points were considered: (1) Is there any relation between known factors such as voltage and the localization of the points of contact with the incidence and the type of complications and sequelae? (2) Do the observations show that wound management and the excision of dead tissues is the most adequate? From factors studied in our patients (voltage, point of entry and pathway of current, associated multiple trauma or flame burns, surgical treatment) we have found that the voltage does not have any influence on the severity of the wound nor on the percentage of sequelae (cataracts, limb amputation, neurologic complications). The current pathway, as well as its points of entry, does not show any relation with the presence of renal failure, cardiac arrhythmia and cataracts. A clear relationship between the point of entry of the current and the appearance of neurologic injury with presence of paralysis and permanent regional anaesthesia at the same level was observed. The presence of associated burns was not related to any other complications or sequelae. For those patients whose length of contact has been shorter we find a lower rate of amputations despite having associated limb fractures. Fasciotomy incisions appear to confer benefit as this series shows that this procedure decreases the rate of limb amputations.     

Effects of insulin on calcium metabolism and platelet aggregation

Poppy seeds from seven different origins (Dutch, Australian, Hungarian, Spanish, Czech, and two Turkish) were analyzed for the amount of opiates present. Four grams of each kind of seeds, equivalent to the amount of seeds on two bagels, were ingested by volunteers. One volunteer also ingested four times the same amount of poppy seeds from the same origin (Spanish). During 24 hours urine samples were obtained and screened for the presence of morphine and codeine using the FPIA technique (cut-off = 200 ng/mL) and a GC/MS confirmation with a limit of detection (LOD) of 25 ng/mL for codeine and morphine. Poppy seeds from different origins contain a wide variation of morphine (2-251 micro g/g) and codeine (0.4-57.1 micro g/g) content. No other opiate could be detected. After ingestion a large interindividual variation of excretion of opiates exists. The testing results from the same kind of seeds ingested four times with a one week interval by the same volunteer also show a poor reproduceability. Several kinds of poppy seeds can give positive testing results (Australian, Hungarian, Spanish and one kind of Turkish seeds). Within 24 hours all testing results became negative.     

Gender does not affect fetal heart rate variation

There is a widespread but erroneous view among the lay public that there is a difference in the baseline fetal heart rate between male and female fetuses. It has been suggested that this perception might reflect an actual difference in fetal heart rate variability. Therefore, we studied the fetal heart rate variation in 79 white European women using the Sonicaid System 8002 computer. Fourty-four of the fetuses were male and 35 were female. There was no significant gender difference in any measured aspect of fetal heart rate variation.     

Aging does not affect gray matter asymmetry.

Previous research has shown that asymmetry of brain activity is decreased in older adults. This study investigates whether cortical gray matter asymmetry also shows age-related differences, and whether gray matter asymmetry differs between cognitively stable persons and persons who have shown profound age-related declines in cognitive functioning. In addition, we have examined whether prodromal dementia affects the study outcome. The gray matter volumes of seven prefrontal and temporal regions of interest were delineated on T1-weighted MRI scans in 70 adults aged between 52 and 84 years. Statistical analyses were conducted with and without participants who developed dementia within 6 years after the MRI scan session. It was found that asymmetry did not differ over the age range of 52–84 years of age. This result did not change when data from participants who were diagnosed with dementia within 6 years after MRI assessment were excluded from the analysis. In addition, no gray matter asymmetry differences were found between cognitively stable participants and participants who showed cognitive decline. We conclude that alterations in gray matter asymmetry may not be part of the healthy aging process. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Inhibition of perioperative platelet aggregation using toradol (ketorolac)

Traditionally, aspirin is used as an inexpensive and usually well-tolerated agent to accomplish inhibition of platelet aggregation after microvascular surgery. Occasionally, however, aspirin is contraindicated. We have successfully used Toradol (ketorolac) after microvascular tissue transfer to inhibit platelet aggregation postoperatively, and documented this in our laboratory. We present two individuals on our surgical service requiring microvascular free tissue transfer with documented allergic reactions to aspirin. Platelet function was successfully suppressed while on the Toradol regimen, and this function returned to normal within 24 hours after stopping this therapy. We believe this agent may have some use for the microvascular surgeon for the population of patients in which aspirin is contraindicated or difficult to administer.     

High dose intravenous immunoglobulin does not affect complement-bacteria interactions

Pooled IgG preparations for i.v. use (IVIg) have been shown to possess anticomplementary activity in autoimmune and systemic inflammatory diseases. Both in vitro and in vivo, IVIg is a preferential acceptor of activated C4 and C3, thus diverting complement activation from the target surface. We explored the effect of IVIg on complement-bacteria interactions in an attempt both to determine the safety of IVIg preparations in relation to natural immunity to bacteria and to extend our knowledge of the physiologic mechanism of action of IVIg. Using both complement-sensitive and complement-resistant bacterial strains, we investigated the effect of IVIg on C3 binding to bacterial surfaces. In all cases, whether complement could be directly activated by bacteria through the classical or the alternative pathway, IVIg had no effect on the amount of C3 bound to bacteria. In addition, IVIg did not inhibit complement-dependent bacterial lysis. Interestingly, increasing concentrations of IVIg induced an increase in C1q binding, suggesting the presence of low affinity complement-fixing antibacterial Abs in certain preparations. Using serum samples from patients treated with IVIg, complement binding to and lysis of complement-sensitive bacterial strains were not modified as compared with normal controls and pretreatment samples, although a decrease in C3 binding to sensitized human erythrocytes was observed. Our data suggest that IVIg does not affect direct complement-bacteria interactions, although it is a potent agent to use for diversion of complement activation on sensitized target surfaces.     

Loss of the signature six carboxyl amino acid tail from ovine interferon-tau does not affect biological activity

Interferon-tau (IFN-tau) is a type I IFN that is secreted from conceptuses of Bovidae (sheep, cattle, and related ruminant ungulates) for a few days during early pregnancy. It acts to prolong the life span of the corpus luteum. All secreted forms of IFN-tau, like the related IFN-omega, are 172 amino acids in length and differ from IFN-alpha and -beta by the presence of six additional amino acids at their carboxyl termini. The aim of this study was to determine whether this carboxyl tail was important for biological activity of IFN-tau, particularly for its antiluteolytic function in ewes. Full-length ovine IFN-tau (p3) and a mutated form truncated by six amino acids at its carboxyl terminal (p3Trn6, 166 amino acids) were produced in Escherichia coli. Both proteins had similar antiviral activities (2.12 +/- 0.92 x 10(8) IU/mg for p3; 1.96 +/- 0.58 x 10(8) IU/mg for p3Trn6) when tested on Madin-Darby bovine kidney (MDBK) cells. Antiproliferative activity, as measured on human Daudi cells by determining the protein concentration required to inhibit growth by 50%, was slightly higher (p < 0.05) for p3Trn6 (7.36 +/- 0.46 pM) than for p3 (13.99 +/- 0.85 pM). Most importantly, p3 and p3Trn6 were equally capable of prolonging the life span of the corpus luteum of nonpregnant ewes when the proteins were administered at doses of either 60 or 300 microg/day into the uterine lumen through indwelling uterine cannulae from Day 10 to Day 18 postestrus. Therefore, the carboxyl-terminal amino acid extension for IFN-tau does not appear to serve a functional role in the action of these proteins.     

Bolus aggregation in the oropharynx does not depend on gravity

The authors report the use of high-performance liquid chromatography-electrospray-tandem mass spectrometry (HPLC-ESI-MS/MS) for the quantification of indomethacin (IND) in plasma with microscale sample preparation. Plasma samples (100 microL) and mefanamic acid (internal standard [IS]), buffered to pH 3.5, were prepared using solid phase extraction and chromatographed using a C8 column. The mobile phase composition was 80% methanol to 20% ammonium acetate buffer (40 mM, pH 5.1). A flow rate of 300 microL per minute was used with a 1-to-12 postcolumn split into the mass spectrometer. Selected reaction monitoring with mass transitions m/z 357.9-->139.0 and m/z 242-->209.0 were used for IND and IS, respectively. The chromatographic analysis time was 4 minutes. The assay was linear from 5 microg/L to 2000 microg/L with interday imprecision (n=5) over the analytic range (5%). At four concentrations (10 microg/L, 25 microg/L, 250 microg/L, 1500 microg/L), assay imprecision was 9% (total coefficient of variation [CV]) and accuracy ranged between 96.5% and 102.8% (n=16). The absolute recovery of IND and IS was 74% (n=8) and 95% (n=24), respectively. This method was developed and validated in less than 10 working days, had a lower limit of quantification than reported HPLC-ultraviolet (UV) methods, and uses small sample volumes. These factors illustrate the power of HPLC-ESI-MS/MS for drug analysis. Furthermore, the ability of this method to measure IND over a wide concentration range makes it suitable for therapeutic drug monitoring and pharmacokinetic studies.     

L-NAME does not affect exercise-induced pulmonary hypertension in thoroughbred horses

The present study was carried out to examine the effects of nitric oxide synthase inhibition with Nomega-nitro-L-arginine methyl ester (L-NAME) on the right atrial as well as on the pulmonary arterial, capillary, and venous blood pressures of horses during rest and exercise performed at maximal heart rate (HRmax). Experiments were carried out on seven healthy, sound, exercise-trained Thoroughbred horses. Using catheter-tip manometers, with signals referenced at the point of the shoulder, we determined phasic and mean right atrial and pulmonary vascular pressures in two sets of experiments [control (no medications) and L-NAME (20 mg/kg iv given 10 min before exercise studies)]. The studies were carried out in random order 7 days apart. Measurements were made at rest and during treadmill exercise performed on a 5% uphill grade at 6, 8, and 14.2 m/s. Exercise on a 5% uphill grade at 14.2 m/s elicited HRmax and could not be sustained for >90 s. In quietly standing horses, L-NAME administration caused a significant rise in right atrial, as well as pulmonary arterial, capillary, and venous pressures. This indicates that nitric oxide synthase inhibition modifies the basal pulmonary vasomotor tone. In both treatments, exercise caused progressive significant increments in right atrial and pulmonary vascular pressures, but the values recorded in the L-NAME study were not different from those in the control study. The extent of exercise-induced tachycardia was significantly decreased in the L-NAME study at 6 and 8 m/s but not at 14.2 m/s. Thus, L-NAME administration may not modify the equine pulmonary vascular tone during exercise at HRmax. However, as indicated by a significant reduction in heart rate, L-NAME seems to modify the sympathoneurohumoral response to submaximal exercise.     

Maternal malnutrition does not affect fetal hepatic glycogen synthase ontogeny

Maternal malnutrition late in pregnancy results in the reduced storage of fetal hepatic glycogen in the final days of gestation and an accentuation of normal birth-related hypoglycemia. It was of interest to determine whether or not low glycogen levels resulted when maternal malnutrition disrupted the normal ontogeny of fetal hepatic glycogen synthase, an important glycogenic enzyme. A defect in this enzyme would be expected to seriously affect prenatal and postnatal glycogen synthesis. For this study, livers were removed from fetuses from malnourished (50% of normal dietary intake) mice, as well as from ad libitum-fed mice, and used for the determination of hepatic glycogen, glycogen synthase activity, and glycogen synthase protein levels. In this paper we report that maternal dietary restriction late in pregnancy produces growth-retarded fetuses with severely reduced hepatic glycogen levels, but the normal ontogenic changes in the quantity and activity of hepatic glycogen synthase were not affected. It is especially significant that the accumulation of glycogen synthase occurred despite the minimal level of natural substrate available for the enzyme. These results suggest that the accumulation and activity of hepatic glycogen synthase during late gestation is related to developmental events rather than levels of substrate or glycogen.     

High D-glucose does not affect binding of alpha-tocopherol to human erythrocytes

The role of alpha-tocopherol uptake system in human erythrocyte in the uptake of plasma alpha-tocopherol has been suggested. However no information is available on alpha-tocopherol uptake activity of human erythrocytes in the presence of high levels of D-glucose which is known to lead to pathological alterations in different cells including human erythrocytes. Therefore, in order to examine the effect of D-glucose on the binding of alpha-tocopherol to human erythrocytes, the binding characteristics of alpha-tocopherol to these cells were established first. Binding of [3H]alpha-tocopherol to human erythrocytes was both saturable and specific. Scatchard analysis of alpha-tocopherol binding to these cells showed the presence of two independent classes of binding sites with widely different affinities. The high affinity binding sites had a dissociation constant (Kd1) of 90 nM with a binding capacity (n1) of 900 sites per cell, whereas the low affinity binding sites had a dissociation constant (Kd2) of 5.2 microM and a binding capacity (n2) of 105,400 sites per cell. Trypsin treatment abolished all the alpha-tocopherol binding activity. Competition for the binding of alpha-tocopherol to human erythrocytes was effective with other homologues of alpha-tocopherol (beta-tocopherol, gamma-tocopherol and delta-tocopherol) and their potency was almost equal to alpha-tocopherol itself. The order of preference was alpha-tocopherol > beta-tocopherol > or = gamma-tocopherol > or = delta-tocopherol. Incubation of human erythrocytes with various concentrations of D-glucose did not affect alpha-tocopherol uptake activity. Our data demonstrate the presence of an alpha-tocopherol uptake system in human erythrocytes and that the alpha-tocopherol uptake activity is not modulated by the presence of D-glucose.     

Zinc status does not affect aluminum deposition in tissues of rats

To examine whether zinc deficiency would increase the toxicity of dietary aluminum, weanling, male Sprague-Dawley rats were fed purified diets containing either 2 or 30 mg Zn/kg diet, with or without 500 mg Al/kg diet for 28 d. Individually pair-fed rats were fed the 30 mg Zn/kg diet with or without added aluminum to control for inanition secondary to zinc deficiency. Rats fed the 2 micrograms Zn/kg diet showed evidence of zinc deficiency, including anorexia, growth retardation, and depressed concentrations of zinc in tibias and livers. Zinc deficiency did not significantly increase the concentrations of aluminum in the tibias, livers, kidneys, or regions of the brain examined (cerebrum, cerebellum, midbrain, and hippocampus). Inclusion of aluminum in the diet did not alter aluminum concentrations in the various tissues. Under the conditions of this study, zinc deficiency did not result in greater sensitivity to dietary aluminum exposure.