Anti-thrombotic action of sulfated polysaccharides on thrombosis caused by thromboplastin

The antithrombotic effect of modified sulfated polysaccharides on a model of thromboplastin-induced thrombosis was investigated, which made it possible to evaluate the effectiveness of sulfated polysaccharides as a direct anticoagulant that increases the tolerance of animals to effects causing intravascular thrombosis.

Replacement of traditional prothrombin time monitoring with the new Fiix prothrombin time increases the efficacy of warfarin without increasing bleeding. A review article

The antithrombotic effect of vitamin K antagonists (VKA) depends on controlled lowering of the activity of factors (F) II and X whereas reductions in FVII and FIX play little role. PT-INR based monitoring, however, is highly influenced by FVII, which has the shortest half-life of vitamin K-dependent coagulation factors. Hence, variability in the anticoagulant effect of VKA may be partly secondary to an inherent flaw of the traditional monitoring test itself. The Fiix prothrombin time (Fiix-PT) is a novel test that is only sensitive to reductions in FII and FX and is intended to stabilize the VKA effect. Two clinical studies have now demonstrated that when warfarin is monitored with the Fiix-PT based normalized ratio (Fiix-NR) instead of PT-INR, anticoagulation is stabilized and less testing and fewer dose adjustments are needed. Furthermore, the relative risk of thromboembolism was reduced by 50–56% in these studies without an increase in major bleeding.

Silibinin augments the effect of clopidogrel on atherosclerosis in diabetic ApoE deficiency mice

BACKGROUND: Diabetes mellitus (DM) abolishes the antithrombotic effect of Clopidogrel. Here, we investigated the synergistic effect of Silibinin on Clopidogrel-mediated atherosclerosis treatment in diabetic mice. METHODS: ApoE–/– mice were fed with high-fat diet (HFD) to establish the atherosclerotic model with diabetes. Animals were treated with Clopidogrel, Silibinin, or the combined to evaluate the protective effects on atherosclerosis and diabetes through Oil-red-O staining, qRT-PCR, Western blot, and metabolic measurements. Platelet activation and aggregation ex vivo assays were performed to detect the anti-thrombotic effect of different administrations. RESULTS: Silibinin significantly enhanced the inhibitory effect of Clopidogrel on atherosclerosis in DM mice. Co-administration of Silibinin with Clopidogrel remarkedly reduced the aortic lesion, inflammation, and endothelial dysfunction in aorta roots, and diabetic symptoms were significantly improved by the Silibinin-Clopidogrel treatment in HFD-fed ApoE–/– mice. Interestingly, the anti-thrombotic effect of Clopidogrel was further augmented by the Silibinin treatment in atherosclerotic mice. CONCLUSION: In atherosclerotic mouse model, Silibinin significantly improves the effect of Clopidogrel on atherosclerosis.

Synthesis and Bioactivities of Marine Pyran-Isoindolone Derivatives as Potential Antithrombotic Agents

2,5-Bis-[8-(4,8-dimethyl-nona-3,7-dienyl)-5,7-dihydroxy-8-methyl-3-keto-1,2,7,8-teraahydro-6H-pyran[a]isoindol-2-yl]-pentanoic acid (FGFC1) is a marine pyran-isoindolone derivative isolated from a rare marine microorganism Stachybotrys longispora FG216, which showed moderate antithrombotic(fibrinolytic) activity. To further enhance its antithrombotic effect, a series of new FGFC1 derivatives (F1–F7) were synthesized via chemical modification at C-2 and C-2′ phenol groups moieties and C-1″ carboxyl group. Their fibrinolytic activities in vitro were evaluated. Among the derivatives, F1–F4 and F6 showed significant fibrinolytic activities with EC50 of 59.7, 87.1, 66.6, 82.8, and 42.3 μM, respectively, via enhancement of urokinase activity. Notably, derivative F6 presented the most remarkable fibrinolytic activity (2.72-fold than that of FGFC1). Furthermore, the cytotoxicity of derivative F6 was tested as well as expression of Fas/Apo-1 and IL-1 on HeLa cells. The results showed that, compared to FGFC1, derivative F6 possessed moderate cytotoxicity and apoptotic effect on HeLa cells (statistical significance p > 0.1), making F6 a potential antithrombotic agent towards clinical application.

Are all wines made from various grape varieties beneficial in the prevention of myocardial infarction and stroke?

Aim: Epidemiologic studies support the assumption (French paradox hypothesis) that drinking red wine is beneficial in the prevention of cardiovascular diseases. Our recent works however cast doubt on such claim. Earlier we have shown that the antithrombotic activity of various fruits and vegetables mainly depends on their varieties. For this reason, several varieties of red and white grapes were tested for antithrombotic effect in animal experiments. Results: Antithrombotic effect of 45 red and white grape varieties were assessed in the present study. Out of the 45, one red grape variety showed antithrombotic effect, while the majority of red and white grape varieties enhanced thrombosis. Conclusion: Most red and white grape varieties enhanced thrombotic activity of blood.

Conservative treatment for intermittent claudication

This paper discusses the issues emerging during the treatment of lower-limb arterial diseases and intermittent claudication. According to the international and Russian guidelines, the common management strategy for intermittent claudication is as follows: conservative treatment is recommended in patients without limiting intermittent claudication who can walk 30 m or more without pain. Drugs that are prescribed is these patients are addressed. No large well-designed studies on most of these drugs were conducted, therefore, it is challenging to assess their efficacy in patients with intermittent claudication. The authors focus on cilostazol that has the largest evidence base. This drug is included in the Russian and international clinical guidelines. Several students demonstrate that cilostazol provides antithrombotic effect, stabilizes atherosclerotic plaques, prevents hyperplasia of neointima and restenosis after vascular procedures, improves lipid metabolism, and significantly increases pain-free walking distance (intermittent claudication distance). Recent studies show that cilostazol can be used in the complex treatment for COVID-19 due to pleiotropic mechanism of action. KEYWORDS: lower-limb arterial diseases, intermittent claudication, conservative treatment, cilostazol, COVID-19, restenosis, antiplatelet therapy. FOR CITATION: Kuznetsov M.R., Reshetov I.V., Sapelkin S.V., Yasnopol’skaya N.V. Conservative treatment for intermittent claudication. Russian Medical Inquiry. 2021;5(4):212–217 (in Russ.). DOI: 10.32364/2587-6821-2021-5-4-212-217.

Low molecular weight heparins dosing and anti-factor Xa activity in patients with novel coronavirus infection COVID-19.

Низкомолекулярные гепарины (НМГ) рекомендованы всем госпитализированным пациентам с COVID-19. Однако эффективная доза НМГ неизвестна, и эскалация дозы НМГ представляется уместной для лечения COVID-19-ассоциированной коагулопатии. Цель исследования: анализ дозирования НМГ для лечения COVID-19-ассоциированной коагулопатии, а также индикаторов, указывающих на необходимость коррекции доз этих препаратов. Материалы и методы. В период апрель-июнь 2020 г. обследовано 49 человек с диагнозом COVID-19. НМГ получили 43 пациента: 25 человек — эноксапарин натрия, 18 — далтепарин натрия. При лабораторном обследовании определяли С-реактивный белок, количество тромбоцитов, активированное частичное тромбопластиновое время, тромбиновое время, концентрацию фибриногена, активность антитромбина III, протромбиновое время, концентрацию Д-димера и анти-фактор Ха активность (анти- Ха активность). Данные были представлены как медиана (Me), нижний (LQ) и верхний (UQ) квартили. Статистический анализ включал в себя проверку на нормальность распределения по критерию Шапиро–Уилка, сравнение независимых групп по критерию Манна–Уитни при уровне значимости < 0,05, корреляционный анализ с применением критерия Спирмена, регрессионный анализ с использованием F-критерия. Многомерный поэтапный анализ результатов исследования проводили методами кластерного, дискриминантного и ROC-анализа. Результаты. Установлено, что воспалительный ответ у мужчин и у женщин протекает с различающимися акцентами в рамках системы гемостаза. Если анти- Ха активность была ниже 0,4 МЕ / мл, то выбранная доза НМГ никак не влияла ни на процессы тромбообразования и воспаления, ни на течение заболевания в целом. При анти- Ха активности в диапазоне 0,4–0,6 МЕ / мл воспалительный ответ также преодолевал эффект НМГ. Только при анти- Ха активности > 0,6 МЕ / мл была выявлена достоверная корреляция между анти- Ха активностью и суточной дозой НМГ (r = 0,493; p = 0,031). Выявление в этой группе такой связи означает, что часть поступившего в организм НМГ уже была «потрачена» на противовоспалительные цели, а оставшаяся проявила эффект, направленный на другую цель назначения НМГ, т. е. собственно антитромботический. При этом ROC-анализ не подтвердил значимость концентрации фибриногена в прогнозе достижения антитромботической эффективности НМГ. Кластерный анализ достоверно разделил исходную выборку в точке анти- Ха активность = 0,6 ЕД / мл. Из 43 пациентов, получивших НМГ, только у 15 (34,9%) выбранная доза НМГ анти- Ха активность > 0,6 ЕД / мл, тогда как у оставшихся анти- Ха активность оказалась ниже данного значения, несмотря на большую вариацию полученного НМГ: AUC = 0,482 (95% ДИ = 0,298–0,665) со статистической значимостью p = 0,848. Дискриминантный анализ показал, а ROC-анализ подтвердил, что для до- стижения антитромботического эффекта требуется коррекция дозы с учетом веса тела пациента, а целевым значением анти- Ха активности является 0,65 ME / мл. Заключение. Антитромботический эффект как искомый результат применения НМГ достижим только при дозировании с учетом массы тела пациента, независимо от того, снижена она, нормальная или повышена. Развитие антитромботического эффекта должно выявляться, а его стабильность подтверждаться на основе определения анти- Ха активности, которая должна быть не менее 0,65 МЕ/мл. Анти- Ха активность ниже данного значения может служить указанием на необходимость коррекции дозы НМГ у пациентов с COVID-19-ассоциированной коагулопатией. Background. Low molecular weight heparins (LMWH) are guided for all in-hospital patients with COVID-19. However LMWH effective dose is still unknown. Escalating the LMWH dose seems appropriate for the treatment of COVID-19-associated coagulopathy. Objectives: to explore the LMWHs doses effects in the treatment of COVID-19-associated coagulopathy, and to fi nd indicators signaling the need to adjust the LMWH dose. Patients / Methods. From April to June 2020, 49 patients with COVID-19 were examined. LMWH were given to 43 patients: 25 of them received enoxaparin sodium, 18 — dalteparin sodium. Lab testing included C-reactive protein, platelet count, activated partial thromboplastin time, thrombin time, fibrinogen, antithrombin III, prothrombin time, D-dimer, and anti-factor Xa activity (anti- Xa activity). The data were presented as median (Me), lower (LQ) and upper (UQ) quartiles. Statistical analysis included the check of the distribution normality by Shapiro–Wilk test, comparing independent groups with Mann- Whitney test for p < 0.05, correlation analysis with Spearman test, and regression analysis with the F-test. Multivariate step-by-step analysis of data was performed using cluster analysis, discriminant analysis and ROC-analysis. Results. It was found that the inflammatory response reflects differently for hemostatic system in men and women. When anti-Xa activity was < 0.4 IU / ml, the LMWH selected dose did not affect either the processes of thrombosis and inflammation, or the course of the disease as a whole. When anti- Xa activity was within 0.4–0.6 IU / ml, the inflammation overcame the LMWH effect as well. A significant correlation between anti- Xa activity and the LMWH daily dose (r = 0.493; p = 0.031) was found only for anti-Xa activity > 0.6 IU / ml. That does mean that part of the administered LMWH was already “spent” for anti-inflammatory purposes, and the remaining part was enough to develop an antithrombotic effect. Other result was that ROC-analysis did not confirm the fibrinogen value for the forecast of LMWH antithrombotic effectiveness. Cluster analysis divided significantly the initial sample at the point with anti- Xa activity = 0.6 IU / ml. Of the 43 patients received LMWH, the selected LMWH dose provided anti- Xa activity > 0.6 IU / ml in 15 (34.9%) only, while in other patients the anti- Xa activity was lower despite a wide variation in the LMWH doses: AUC = 0.482 (95% CI = 0.298–0.665; p = 0.848). Discriminant analysis showed, and then ROC-analysis confirmed, that to an antithrombotic effect, LMWH dose adjustment is required taking into account the patient’s body weight, and the target value of anti- Xa activity is 0.65 IU / ml. Conclusions. The antithrombotic effect as the desired result of the LMWH use is achievable only under dosing with the patient’s body weight regardless of whether it is reduced, normal or increased. The LMWH antithrombotic effect should be detected and then its stability confirmed by testing the anti- Xa activity which should be at least 0.65 IU / ml. Lower anti- Xa activity may indicate the need for LMWH dose adjustment in patients with COVID-19-associated coagulopathy.

Selatogrel, the reversible and specific P2Y12 receptor antagonist, does not interfere with haemostasis

Background Combination of a P2Y12 receptor (P2Y12R) antagonist (clopidogrel, prasugrel, ticagrelor) with aspirin is the recommended standard of care for patients with acute coronary syndrome. Selatogrel is a reversible and potent antagonist of P2Y12R. Interestingly, in an experimental thrombosis model in rat, at equivalent antithrombotic effect, blood loss was lower in the presence of selatogrel, compared with clopidogrel or ticagrelor. Purpose To characterise the lower risk of bleeding previously observed with selatogrel Methods Mechanistic studies were performed to profile laser-induced thrombosis in wild-type and P2Y12 deficient mice with real-time intravital microscopy. Ticagrelor and clopidogrel were used as selatogrel comparators. Results Selatogrel, ticagrelor and clopidogrel dose-dependently inhibited laser-induced platelet thrombus formation. At maximal antithrombotic effect, only small mural platelets aggregates, corresponding to the haemostatic seals, were present. The phenotype of these haemostatic seals depended on the P2Y12R antagonist used. In the presence of clopidogrel or ticagrelor, the stability of haemostatic seals was reduced. In contrast, in the presence of selatogrel, the apparent stability was not disturbed. Moreover, equivalent antithrombotic dosing regimens of ticagrelor and clopidogrel interfered with laser-induced calcium mobilisation in the endothelium, restricted subsequent neutrophil adhesion and thus reduced fibrin-mediated stabilisation of the haemostatic seals in wild type mice. The effects of ticagrelor were also observed in P2Y12R-deficient mice, indicating that the effects are P2Y12R independent and off-target. In contrast, an equivalent antithrombotic dosing regimen of selatogrel did not interfere with the process of haemostasis in wild-type or P2Y12R-deficient mice. The degree of interference with the stability of the haemostatic seals correlated with the blood loss profile. The dosing regimens of clopidogrel and ticagrelor, corresponding to the equivalent antithrombotic effects, induced a more pronounced increase in blood loss than that observed with selatogrel. Conclusion Our data offer a novel mechanistic explanation for the differences in bleeding risk of clopidogrel, ticagrelor and selatogrel. Clopidogrel and ticagrelor were found to interfere with haemostasis due to off-target activities. In contrast, selatogrel did not interfere with haemostasis in wild-type and P2Y12-deficient mice, inferring that the process of haemostasis, as defined by formation of haemostatic seals, is independent of P2Y12R. In addition, our data emphasize that the absence of interference with haemostasis is paramount to preserve the advantage of P2Y12R antagonism. Funding Acknowledgement Type of funding source: Private company. Main funding source(s): Idorsia Pharmaceuticals Ltd. Allschwil, Switzerland