Increased platelet reactivity and platelet–leukocyte aggregation after elective coronary bypass surgery

Inflammatory mechanisms are activated, and thrombotic complications occur during the initial months after coronary artery bypass grafting (CABG). Therefore, changes over time of platelet activation and platelet–leukocyte interactions after CABG are of interest. Whole-blood flow cytometry was performed before, and 4–6 days, one month, and three months after elective CABG in 54 men with stable coronary artery disease treated with acetylsalicylic acid (ASA). Single platelets and platelet–leukocyte aggregates (PLAs) among monocytes (P-Mon), neutrophils (P-Neu), and lymphocytes (P-Lym) were studied without and with stimulation by submaximal concentrations of ADP, thrombin, and the thromboxane analog U46619. White blood cell counts were increased during the initial postoperative course, and platelet counts were increased after one month. Platelet P-selectin expression was significantly enhanced at one month when stimulated by thrombin and U46619 and at three months with ADP and thrombin. All PLAs subtypes were increased at one month without stimulation in vitro. P-Mon and P-Neu stimulated by ADP, thrombin, or U46619 were significantly increased one month after the operation but decreased compared to baseline at three months. Agonist stimulated P-Lyms were increased at one month and remained increased at three months after ADP stimulation. There was significant platelet activation and formation of PLAs unstimulated and after agonist stimulation by ADP, thrombin, and a thromboxane analog after CABG in patients with stable coronary artery disease irrespective of ASA treatment. Changes observed up to three months after CABG support further studies of the clinical implications of protracted increases in platelet activation and platelet–leukocyte interactions.     

Human platelet gel supernatant inactivates opportunistic wound pathogens on skin

Activation of human platelets produces a gel-like substance referred to as platelet rich plasma or platelet gel. Platelet gel is used clinically to promote wound healing; it also exhibits antimicrobial properties that may aid in the healing of infected wounds. The purpose of this study was to quantify the efficacy of human platelet gel against the opportunistic bacterial wound pathogens Acinetobacter baumannii, Pseudomonas aeruginosa, and Staphylococcus aureus on skin. These opportunistic pathogens may exhibit extensive antibiotic resistance, necessitating the development of alternative treatment options. The antimicrobial efficacy of platelet gel supernatants was quantified using an in vitro broth dilution assay, an ex vivo inoculated skin assay, and in an in vivo skin decontamination assay. Human platelet gel supernatants were highly bactericidal against A. baumannii and moderately but significantly bactericidal against S. aureus in vitro and in the ex vivo skin model. P. aeruginosa was not inactivated in vitro; a low but significant inactivation level was observed ex vivo. These supernatants were quite effective at inactivating a model organism on skin in vivo. These results suggest application of platelet gel has potential clinical applicability, not only in the acceleration of wound healing, but also against relevant bacteria causing wound infections.     

Antibacterial synergy between quercetin and polyphenolic acids against bacterial pathogens of fish

ObjectiveTo evaluate combinations of quercetin with gallic acid, p-anisic acid and cinnamic acid in vitro for synergistic activity against common Gram-negative bacterial pathogens of fish viz., Aeromonas hydrophila, Aeromonas salmonicida and Edwardsiella tarda.MethodsAntibacterial activity of quercetin, gallic acid, p-anisic acid and cinnamic acid was determined against selected bacterial pathogens individually, followed by combination of quercetin with polyphenolic acids using serial microplate dilution method measuring minimum inhibitory concentrations. Fractional inhibitory concentration indices were calculated.ResultsQuercetin and other polyphenolic compounds exhibited antibacterial action against the selected fish pathogens with mean minimum inhibitory concentrations ranging from 0.83 to 2.5 mg/mL. It was observed that fractional inhibitory concentration indices for combination of quercetin with gallic acid, p-anisic acid or cinnamic acid against Aeromonas salmonicida were less than 0.5, indicating synergistic interaction. However, the above combinations produced additive antimicrobial activity against Aeromonas hydrophila and Edwardsiella tarda.ConclusionsPositive antibacterial interaction was evident between quercetin and selected polyphenolic acids in vitro.     

Antibacterial activity and kill kinetics of amoxicillin-clavulanic acid combinations against Escherichia coli and Klebsiella aerogenes

Combinations of amoxicillin and clavulanic acid were tested against 11 Escherichia coli strains and five Klebsiella aerogenes strains. Apart from one E. coli, the strains were highly resistant to amoxicillin due to beta-lactamase production. Synergy was demonstrated in all strains by agar dilution. Synergy was detected against the beta-lactamase-producing strains under simulated in vivo conditions with constantly decreasing concentrations simulating in vivo pharmacokinetics. The correlation between antibacterial activity determined by minimum inhibitory concentrations and bacterial kill kinetics in the in vivo simulation model was acceptable. A higher bacterial kill rate was observed when the antibiotic dosage was increased beyond the minimum concentration where an antibacterial effect was seen; this was not demonstrable by traditional agar dilution tests. In combination, a greater relative amount of amoxicillin compared to clavulanic acid allows a reduction in the total amount of antimicrobial agents with the same degree of antibacterial activity.     

Effects of FEIBA on platelet and leucocyte activation in severe haemophilia patients with inhibitors

Factor eight inhibitory bypassing agent (FEIBA) is used as a therapeutic option in haemophilia patients who have developed inhibitors. The measurement of thrombin generation has been applied to monitor the efficacy of FEIBA. However, a major concern about the clinical use of FEIBA is whether or not an increase in thrombin activity causes subsequent platelet activation and risk of thrombosis. Our aim is to evaluate whether FEIBA causes platelet and leucocyte activation in haemophilia patients with inhibitors. We evaluated the effects of FEIBA on platelet and leucocyte activity in correlation with thrombin generation. Initially, an in vitro study was conducted to evaluate the effects of FEIBA on platelet and leucocyte activity (using flow cytometry) using peripheral blood from normal volunteers. We then performed an ex vivo study looking at the effect of FEIBA on the above parameters in two haemophiliacs with high-titre inhibitors. A parallel study was also carried out ex vivo to evaluate thrombin generation using a thrombinoscope. FEIBA did not cause platelet or leucocyte activation in either the in vitro or ex vivo studies but showed a predictable increase in thrombin generation. Our study is the first one to address the effect of FEIBA on platelet and leucocyte function. We found no evidence of ‘systemic’ platelet activation. The findings suggest that whilst FEIBA improves global haemostasis, platelet activation is likely to be contained to the site of injury and systemic platelet activation, a previously feared consequence of FEIBA infusion that that may have contributed to thrombotic risk is absent.     

Evaluation of extracts and essential oil from Callistemon viminalis leaves: Antibacterial and antioxidant activities,total phenolic and flavonoid contents

ObjectiveTo investigate antioxidant and antibacterial activities of Callistemon viminalis (C. viminalis) leaves.MethodsThe essential oil of C. viminalis leaves obtained by hydro-distillation was analyzed by GC/MS. Different extracts were tested for total phenolic and flavonoid contents and in vitro antioxidant (DPPH assay) and antibacterial (agar disc diffusion and 96-well micro-plates methods) actives.ResultsFourteen components were identified in the essential oil, representing 98.94% of the total oil. The major components were 1,8-cineole (64.53%) and α-pinene (9.69%). Leaf essential oil exhibited the highest antioxidant activity of (88.60±1.51)% comparable to gallic acid, a standard compound [(80.00±2.12)%]. Additionally, the biggest zone of inhibitions against the studied bacterial strains was observed by the essential oil when compared to the standard antibiotic (tetracycline). The crude methanol extract and ethyl acetate fraction had a significant antibacterial activity against the tested bacterial strains.ConclusionsIt can be suggested that C. viminalis is a great potential source of antibacterial and antioxidant compounds useful for new antimicrobial drugs from the natural basis. The present study revealed that the essential oil as well as the methanol extracts and ethyl acetate fraction of C. viminalis leaves exhibited highly significant antibacterial activity against the tested bacterial strains.     

Evaluation of wound healing and antimicrobial potentials of Ixora coccinea root extract

ObjectiveTo evaluate the wound healing and antimicrobial activity of root extracts of Ixora coccinea (I. coccinea).MethodsTo investigate the wound healing efficacy of root extract of I. coccinea Linn, five groups of animals were divided each containing six animals. Two wound models including incision and excision wound models were used in this study. The parameters studied were tensile strength on incision wound model and in terms of wound contraction for excision wound model were compared with standard Nitrofurazone (NFZ) ointment (0.2% w/w). Six extracts (ethanol, aqueous, petroleum ether, benzene, chloroform and ethyl acetate) of I. coccinea were screened for in vitro growth inhibiting activity against different bacterial strains viz, Staphylococcus aureus, Bacillus pumilius, Enterococcus faecalis, Escherichia coli, Salmonella typhi and Pseudomonas aeruginosa and fungi Candida albicans and Aspergillus niger were compared with the standard drugs ciprofloxacin and chloramphenicol for antibacterial and griseofulvin for antifungal screening. The serial dilution and cup (or) well plate methods were used for the antimicrobial study and MIC was determined.ResultsThe ethanolic extract showed significant (P<0.001) wound healing activity when compared to standard drug NFZ with respect to normal control group. Amongst all, ethanolic extract showed highly significant antibacterial activity against all bacterial strains used in this study when compared to standard. The aqueous extract showed moderate significant inhibition against all bacterial strains when compared to standard. All the extracts were shown negligible activity against the fungal strains used in this study.ConclusionsThe ethanolic root extract of I. coccinea showed pronounced wound healing and antibacterial activity. The probable reason to heal the wound was that the external application of the extract prevented the microbes to invade through the wound thus the protection of wound occurs against the infection of the various organisms.     

Studies on Platelet Factor 3 Activity

A material consisting of 13 normal controls and 32 patients suffering from various types of secondary thrombocytopathy and some special cases has been tested by a modified thrombin generation test and Stypven clotting time in order to evaluate platelet factor 3 activity. Intact platelet suspensions, platelets damaged by freezing and thawing or ultrasonic vibrations and phospholipid extracts have been added to platelet-free, non-activated citrated plasma prepared from the same normal person in all experiments. The effect on velocity and amount of thrombinformation and on Stypven clotting time have been estimated in the total group. The results have been evaluated statistically. The modified thrombin generation test did not show any significant differences in activity in any cases tested. The Stypven-test was technically much more satisfactory and significantly less activity was found using platelets from patients with hepatic cirrhosis. The concentration of phosphatidylserine was normal in these platelets. In vitro experiments with surface-active agents support the hypothesis, that surface charge of phosphatide micelles are of decisive importance for their coagulation accelerating effect.     

Platelets significantly modify procoagulant activities in haemophilia A

Summary. Haemophilia A replacement therapy is dosed according to patient’s weight and plasma FVIII activity (FVIII:C). The FVIII interacts with platelet membrane but limited data on the impact of platelet procoagulant activity (PCA) are available in haemophilia A. Our aim was to characterize individual PCA in vitro in 20 adult haemophilia A patients at various FVIII:C levels. We detected thrombin generation in platelet‐poor (PPP) and platelet‐rich plasma (PRP) using: (i) calibrated automated thrombography (CAT) triggered with tissue factor, (ii) adhesion‐induced PCA upon collagen and (iii) annexin V binding, expression of P‐selectin and active glycoprotein (GP) IIbIIIa on platelets after stimulation of GPVI with collagen‐related peptide. The FVIII:C levels varied between <1% and 37%. Thrombin generation was individual and strongly enforced by platelets and associated within the three methods. Range of thrombin generation was maximal (up to 30‐fold) at FVIII:C levels 1–5%, underlining the impact of platelets in the presence of traces of replacement therapy. At FVIII:C > 5% platelet contribution in the variance faded. Platelet PCA and P‐selectin exposure lead to a fivefold variation. Intriguingly, at FVIII:C < 1% thrombin generation in PPP associated negatively with platelet GPVI activation, suggestive of a regulatory interplay between plasma and platelets. In haemophilia A, the variability in thrombin generation is partially related to plasma FVIII:C, but mainly dependent on platelet procoagulant capacity. Annexin V binding and PCA in response to activation by collagen receptors contribute to this variability. In all, platelet PCA at least following collagen interaction significantly impacts thrombin generation in haemophilia A.     

Antimicrobial properties of platelet-rich preparations. A systematic review of the current pre-clinical evidence

In recent years autologous platelet concentrates (APCs) have become popular in several medicine fields, representing a valuable adjunct to regenerative surgical procedures. Beneficial effects in the control of postsurgical discomfort and infection have also been frequently reported, suggesting that APC may possess anti-inflammatory and antimicrobial properties. The aim of the present review was to summarize the current evidence regarding the antimicrobial effects of platelet concentrates, investigated by in vitro and animal studies. This review was conducted following a systematic approach. An electronic search was performed on MEDLINE, EMBASE and Scopus databases using appropriate search terms, without language or time restrictions. Preclinical studies assessing the antimicrobial activity of APC were included and divided according to the experimental design. Twenty in vitro studies and four animal studies, investigating APC effects on a broad range of microorganisms, were included. In in vitro studies APC reduced the growth of microorganisms during the first hours of incubation, while they could not completely break down the microbial load. In fact, over time a recovery of bacterial growth was always observed, suggesting that APCs display a bacteriostatic rather than a microbicidal activity. All animal studies showed that APC administered by local injections were able to reduce the infection caused by different microorganisms, although to a lesser extent compared to antibiotics. In conclusion, although the exact action mechanisms of interaction with microbial pathogens need further investigation, platelet concentrates proved to have antimicrobial properties, and therefore could represent a useful natural substance for controlling postoperative infections at surgical sites.     

Platelet-rich plasma stimulated by pulse electric fields: Platelet activation,procoagulant markers,growth factor release and cell proliferation

Therapeutic use of activated platelet-rich plasma (PRP) has been explored for wound healing, hemostasis and antimicrobial wound applications. Pulse electric field (PEF) stimulation may provide more consistent platelet activation and avoid complications associated with the addition of bovine thrombin, the current state of the art ex vivo activator of therapeutic PRP. The aim of this study was to compare the ability of PEF, bovine thrombin and thrombin receptor activating peptide (TRAP) to activate human PRP, release growth factors and induce cell proliferation in vitro. Human PRP was prepared in the Harvest SmartPreP2 System and treated with vehicle, PEF, bovine thrombin, TRAP or Triton X-100. Platelet activation and procoagulant markers and microparticle generation were measured by flow cytometry. Released growth factors were measured by ELISA. The releasates were tested for their ability to stimulate proliferation of human epithelial cells in culture. PEF produced more platelet-derived microparticles, P-selectin-positive particles and procoagulant annexin V-positive particles than bovine thrombin or TRAP. These differences were associated with higher levels of released epidermal growth factor after PEF than after bovine thrombin or TRAP but similar levels of platelet-derived, vascular-endothelial, and basic fibroblast growth factors, and platelet factor 4. Supernatant from PEF-treated platelets significantly increased cell proliferation compared to plasma. In conclusion, PEF treatment of fresh PRP results in generation of microparticles, exposure of prothrombotic platelet surfaces, differential release of growth factors compared to bovine thrombin and TRAP and significant cell proliferation. These results, together with PEF's inherent advantages, suggest that PEF may be a superior alternative to bovine thrombin activation of PRP for therapeutic applications.     

Surveillance of multidrug resistance of 10 enteropathogens in a teaching hospital and in vitro efficacy of 25 ethnomedicinal plants used by an Indian aborigine

ObjectiveTo have an antibiogram of hospital acquired (HA) and community acquired (CA) enteropathogens against 16 antibiotics to assess the infection dynamics for plausible help to the antimicrobial stewardship. To check extracts of 25 lesser-known plants used by an Indian aborigine, for antimicrobial efficacy in vitro and as complementary and alternate medicines against resistant pathogens.MethodsTen strains of enteric bacteria (Enterobacter aerogenes, Escherichia coli, Klebsiella sp., Salmonella paratyphi, S. typhi, Shigella boydii, S. dysenteriae, S. flexneri, S. sonnei and Vibrio cholerae) were isolated from clinical samples in 6 months and their antibiotic sensitivity was assessed by the disc-diffusion method. Concentrated aqueous and ethanolic extracts of leaves and barks of plants were used for monitoring their antibacterial potencies, by the agar-well diffusion method.ResultsIsolated bacterial strains were invariably multidrug resistant (MDR). E. coli was the most frequently isolated organism from HA and CA samples, followed next by Klebsiella sp. From the surveillance, it was evident that the distribution of MDR strains of each was more in HA than CA isolates. Aqueous and ethanolic extracts of Aegle marmelos, Azadirachta indica, Cassia fistula, Holarrhena antidysenterica, Salvadora persica and Terminalia arjuna were highly effective against the all isolated enteropathogenic strains. From the preliminary phytochemical analysis, it was confirmed that both extracts of A. indica, T. arjuna and T. alata contained all the detected phytochemicals (alkaloids, glycosides, terpenoids, reducing sugars, saponins, tannins, flavonoids and steroids), which plausibly attributed to their significant antibacterial activity.ConclusionsPhytoextracts were highly effective against the all enteropathogenic bacterial isolates, in vitro. These 25 plants could be used further for the isolation of pure compounds for use as complementary medicines.     

Platelets display potent antimicrobial activity and release human beta-defensin 2

Platelet-rich plasma (PRP) is a potent agent that improves soft tissue and bone healing. By the release of growth factors and cytokines, PRP is believed to locally boost physiologic healing processes. Recently, antimicrobial activity of PRP has been demonstrated against S. aureus strains. Major scientific effort is being put into the understanding and prevention of infections i.e. by delivery of antimicrobial substances. In previous studies we showed the ideal antibacterial activity-profile of the human beta-defensin 2 (hBD-2) for orthopaedic infections and therefore hypothesized that hBD-2 may be the effector of antimicrobial platelet action. Platelet concentrates were produced from human platelet phresis obtained from a hospital blood bank. They were screened by immunohistochemistry, Western Blot and ELISA for the human beta defensin-2. In?vitro susceptibility to PRP was investigated by a standard disc diffusion test with or without pre-incubation of PRP with anti-hBD-2 antibody. SPSS statistical software was used for statistical analysis. PRP contains hBD-2 470?pg/10(9) platelets or 1786?pg/ml, respectively, (ELISA), which was confirmed by immunohistochemistry and Western Blot. In antimicrobial testing, PRP demonstrates effective inhibition of E. coli, B. megaterium, P. aeruginosa, E. faecalis and P. mirabilis. With this study we confirm the previously reported antimicrobial action of platelet concentrates i.e. PRP. In opposition to previously reported effects against gram positive bacteria our study focuses on gram negative and less common gram positive bacteria that do frequently cause clinical complications. We provide a possible molecular mechanism at least for E. coli and P. mirabilis for this effect by the detection of an antimicrobial peptide (hBD-2). This study may advocate the clinical use of PRP by highlighting a new aspect of platelet action.     

Studies on tumor-cell-induced platelet aggregation in human lung cancer cell lines

We investigated the ability of human lung cancer cells of different histological subtypes to cause platelet aggregation. Tumor-cell-induced platelet aggregation (TCIPA) was studied in vitro in 13 human lung cancer cell lines [small-cell lung cancer (SCLC), squamous-cell lung cancer, large-cell lung cancer, adenocarcinoma and alveolar-cell lung cancer]. Three tumor cell lines failed to aggregate platelets in plateletrich plasma, whereas platelet aggregation was induced by 12 cell lines when added to washed platelets and minimal amounts of platelet-poor plasma (0.5% v/v). The thrombin antagonist hirudin inhibited TCIPA in non-small-cell lung cancer cell lines (NSCLC). In SCLC, TCIPA was fully abolished only when the ADP scavenger apyrase was added to hirudin. Thus ADP and thrombin generation by these tumor cell lines are responsible for platelet aggregation. The ability to activate platelets independently of coagulation factors VII and X was demonstrated for 8 cell lines. Electronmiicroscopically, direct tumor-cell/platelet contact was found to be the initiating mechanism of TCIPA in SCLC, whereas tumor-cell/platelet contacts in NSCLC could only be observed at the peak of the aggregation curve. Lung cancer cells activate platelets in vitro by generation of thrombin and/or ADP.Abbreviations TCIPA tumor-cell-induced platelet aggregation - SCLC small-cell lung cancer - NSCLC non-small-cell lung cancer     

Val34Leu polymorphism of plasma factor XIII: biochemistry and epidemiology in familial thrombophilia

Val34Leu polymorphism of the A subunit of coagulation factor XIII (FXIII-A) is located in the activation peptide (AP) just 3 amino acids away from the thrombin cleavage site. This mutation has been associated with a protective effect against occlusive arterial diseases and venous thrombosis; however, its biochemical consequences have not been explored. In the current study it was demonstrated that the intracellular stability and the plasma concentration of FXIII of different Val34Leu genotypes are identical, which suggests that there is no difference in the rate of synthesis and externalization of wild-type and mutant FXIII-A. In contrast, the release of AP by thrombin from the Leu34 allele proceeded significantly faster than from its wild-type Val34 counterpart. By molecular modeling larger interaction energy was calculated between the Leu34 variant and the respective domains of thrombin than between the Val34 variant and thrombin. In agreement with these findings, the activation of mutant plasma FXIII by thrombin was faster and required less thrombin than that of the wild-type variant. Full thrombin activation of purified plasma FXIII of different genotypes, however, resulted in identical specific transglutaminase activities. Similarly, the mean specific FXIII activity in the plasma was the same in the groups with wild-type, heterozygous, and homozygous variants. Faster activation of the Leu34 allele hardly could be associated with its presumed protective effect against venous thrombosis. No such protective effect was observed in a large group of patients with familial thrombophilia.     

Reduced mucosal antimicrobial activity in Crohn's disease of the colon

OBJECTIVES: In order to maintain the mucosal barrier against luminal microorganisms the intestinal epithelial cells synthesise various broad-spectrum antimicrobial peptides including defensins and cathelicidins. Recent studies indicate that both may be deficient in Crohn's disease. To elucidate the possible functional consequences of this deficiency antimicrobial activity in colonic mucosa from patients with inflammatory bowel disease and healthy controls was investigated. METHODS: A flow cytometric assay was established to quantitate bacterial killing and test the antibacterial activity of cationic peptide extracts from colonic biopsies taken from patients with active or inactive ileocolonic or colonic Crohn's disease (n = 22), ulcerative colitis (n = 29) and controls (n = 13) against clinical isolates of Bacteroides vulgatus and Enterococcus faecalis or the reference strains Escherichia coli American Type Culture Collection (ATCC) 25922 and Staphylococcus aureus ATCC 25923. RESULTS: Compared with controls and ulcerative colitis there was a reduced antimicrobial effect in Crohn's disease extracts that was most evident against B. vulgatus. The antimicrobial effect against E. coli and E. faecalis was significantly lower in Crohn's disease compared with ulcerative colitis. Activity against S. aureus disclosed a similar pattern, but was less pronounced. The differences were independent of the inflammation status or concurrent steroid treatment. Bacteria incubated with biopsy extracts from ulcerative colitis patients frequently showed a characteristic change in cell size and granularity, compatible with more extensive membrane disintegration, compared with bacteria incubated with extracts from controls or Crohn's disease. CONCLUSION: Crohn's disease of the colon is characterized by a diminished functional antimicrobial activity that is consistent with the reported low antibacterial peptide expression.     

Sulfadiazine—Chitosan Conjugates and Their Polyelectrolyte Complexes with Hyaluronate Destined to the Management of Burn Wounds

In the present study polyelectrolyte complexes (PECs) based on new sulfadiazine-chitosan conjugates with sodium hyaluronate have been developed with potential use in treatment of burn wounds. The PECs were chemically characterized using Fourier Transform—Infrared Spectroscopy, Scanning Electon Microscopy and Near Infrared Chemical Imaging Technique. The swelling behavior and in vitro sulfadiazine release were also investigated. The antimicrobial activity was evaluated towards three bacterial strains: Escherichia coli, Listeria monocytogenes and Salmonella thyphymurium. The developed PECs demonstrated their antimicrobial efficiency against tested bacterial strains, the PECs containing sulfadiazine-modified chitosan being more active than PECs containing unmodified chitosan.     

Bacterial endotoxin as inhibitor of the enzymatic activity of human thrombin

Endotoxemia caused by bacterial lipopolysaccharides (LPS) deleteriously affects many aspects of hemostasis. Much of this effect is well characterized as being secondary to the LPS-mediated inflammatory response, but direct effects of LPS on coagulation factors may also contribute to disregulation of the hemostatic process. Spectrophotometric assays were used to investigate the effects of LPS from different bacteria on thrombin and plasmin activities. We found that enzymatic activity of purified thrombin, but not plasmin, decreases in the presence of endotoxin. LPS-mediated inhibition of thrombin activity can be reversed by plasma gelsolin and recombinant endotoxin-neutralizing protein. Preincubation of thrombin with LPS before platelet activation results in inhibition of aggregation and secretion. Additionally, a decrease of elastic shear moduli of fibrin gels was observed when their formation was induced with thrombin preincubated with LPS or when LPS was present in fibrinogen solutions during fibrin gel formation. When added to platelet-rich plasma, after activation with collagen, LPS-inhibited thrombin activity. LPS-mediated inhibition of thrombin activity may contribute to the hemostasis dysfunctions observed during endotoxemia.     

Extracts from Trifolium pallidum and Trifolium scabrum aerial parts as modulators of blood platelet adhesion and aggregation

A growing number of reports indicate that some species of clover (Trifolium) may have remarkable medical importance; however, the effects of these plants on blood platelets and hemostasis are inadequately recognized. This work was designed to study the effects of Trifolium pallidum and Trifolium scabrum extracts on the functions of human blood platelets in vitro. Platelet suspensions were preincubated with extracts from aerial parts of T. pallidum (phenolic fraction and clovamide fraction) and T. scabrum (phenolic fraction) at the final concentrations of 12.5, 25, and 50?µg/ml. Then, for platelet activation thrombin (0.1?U/ml), thrombin receptor activating peptide (TRAP; 20?µM), or adenosine diphosphate (ADP; 1?µM) were used. The effects of Trifolium extracts on adhesion of blood platelets to fibrinogen and collagen were determined by enzyme-linked immunosorbent assay (ELISA) method. Platelet aggregation was monitored on a dual-channel Chronolog aggregometer. In these studies, we also compared the action of tested plant extracts with the effects of another antiplatelet plant-derived compound – resveratrol (3,4′,5-trihydroxystilbene). The performed assays demonstrated that the tested extracts might influence the platelet functions in vitro. The inhibitory, concentration-dependent effects of all tested extracts on adhesion of thrombin-stimulated platelets to collagen was found. Both extracts from T. pallidum and from T. scabrum reduced the thrombin-induced platelet adhesion to fibrinogen. Furthermore, in the presence of all three extracts, the platelet aggregation induced by thrombin was slightly inhibited. Our results also indicate that the tested plant extracts (at the highest concentrations used of 50?µg/ml), similar to purified resveratrol, inhibit selected steps of platelet activation stimulated by both proteolytic (thrombin) and nonproteolytic agonists (TRAP or ADP). In the comparative studies, T. pallidum and T. scabrum extracts was not found to be more effective antiaggregatory factor, than resveratrol. Extracts from T. pallidum and T. scabrum aerial parts reveal antiplatelet properties: the antiadhesive effect was similar to that of the reference compound resveratrol, whereas the antiaggregant effect was less marked. The results obtained suggest that these plants may be a promising source of natural compounds, valuable in the prevention of the enhanced activity of blood platelets in numerous cardiovascular diseases, observed in menopausal or postmenopausal women.     

Effect of henna and roselle extracts on pathogenic bacteria

ObjectiveTo investigate the antibacterial effects of water and ethanolic extracts of henna leaves and roselle calyxes against pathogenic bacteria isolated from domestic wastewater.MethodsThe antimicrobial activity was determined in the extracts using agar disc diffusion method. The antibacterial activities of extracts (2.5%, 5.0% and 10.0% w/v) of both henna and roselle were tested against one Gram-positive Bacillius subtilis; two Gram-negative Escherichia coli, Pseudomonas aeruginosa human pathogenic bacteria.ResultsEthanolic extracts had more antimicrobial activity than water extracts. Ethanolic extract of roselle had the highest antibacterial activity against all tested organisms, followed with ethanolic extract of henna. Pseudomonas aeruginosa was the most sensitive bacteria to plant extracts.ConclusionThe results of this study suggested that roselle contains more phyto-chemicals with antimicrobial activity than henna on the bacteria strains under study, and these phyto-chemicals were more effective when extracted by ethanol rather than water.