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Abstract-The effects of stearic acid (C18:0) and trans-fatty acids (trans-FAs) on measures of platelet function and prostacyclin (PGI 2 ) production are poorly understood in humans. In this controlled dietary study, platelet function and endothelial PGI 2 production were studied in healthy humans after they consumed diets rich in C18:0 or trans-FAs. For 5 weeks, 80 subjects consumed a baseline diet high in saturated FAs and were then switched to a diet containing 9.3% of energy as stearic acid or a diet containing 8.7 energy% as trans-FAs from hydrogenated vegetable oils for another 5 weeks. All diets contained 32.2 to 33.9 energy% fat, 14.6 to 15.8 energy% saturated plus trans-FAs, 12.2 to 12.5 energy% cis-monounsaturated, and 2.9 to 3.5 energy% polyunsaturated FAs. No significant differences between the C18:0 and trans-FA diets were found in the urinary excretion of 2,3-dinor-thromboxane B 2 or 2,3-dinor-6-keto-prostaglandin F 1␣ . In vitro production of thromboxane B 2 by platelets as well as urinary excretion of ␤-thromboglobulin were also similar after both diets. Collagen-induced in vitro aggregation was significantly enhanced after the C18:0 diet compared with the trans-FA diet (Pϭ.02), whereas no differences between the diets were found with ADP. 3,4 although this observation has not been consistent. 5,6 Still, data on the thrombogenic properties of these FAs are mostly based on animal studies or in vitro studies with isolated cells. In rats, trans-FAs have inhibited thromboxane production 7 and either inhibited 8 or had no effect 9 on platelet aggregation.It is apparent that stearic acid has a different cholesterolemic effect than other long-chain saturated FAs. Regarding lipoprotein metabolism, stearic acid has been considered neutral with respect to total cholesterol and LDL cholesterol, although HDL cholesterol has decreased in some studies. 10 -12 Whether stearic acid can also be considered neutral with respect to its thrombotic effects is unclear. Evidence from human epidemiological and animal studies suggests that stearic acid enhances platelet aggregation in vitro, indicating its effects on platelet activity, an important aspect of thrombosis and hemostasis. [13][14][15] In vivo indices of platelet activation have been measured in only one human study, in which thromboxane or prostacyclin synthesis did not change after a diet rich in stearic acid. 16In mixed diets, trans-FAs are mainly substituted for saturated FAs, not for liquid oils. The purpose of our study was therefore to compare the atherogenic and thrombogenic properties of stearic acid and trans-monounsaturated FAs in a strictly controlled way in healthy subjects. The results on lipids and lipoproteins 17 as well as coagulation and fibrinolysis factors 18 have been published previously. This article discusses the effects of stearic acid and trans-FAs, especially those on platelet function, as measured by several in vivo and in vitro parameters as well as those on endothelial cell PGI 2 production. Methods SubjectsAltogether 80 healthy ...

The current analytical methods for the various prostanoids require a separate and extended sample workup, derivatization, and gas chromatographic/mass spectrometric detection of each compound. Therefore, we developed and validated a rapid method for the common purification, derivatization, and GC/MS determination of 11-dehydrothromboxane B2, 2,3-dinor-6-keto-PGF1a, PGF2A, PGE2, PGD2, and isoprostanes in urine. A single reversed-phase solid-phase extraction step and modified reaction conditions yielded excellent sample purification at high recoveries and efficient derivatization for all compounds in one vial. The method allows, for the first time, the simultaneous quantification of these index metabolites of systemic thromboxane and prostacyclin synthesis, renal prostaglandin formation, and nonenzymatic in vivo lipid peroxidation in a single GC/MS run with high sensitivity and precision.

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Objectives Aggregation is one of the key critical points limiting the stability of monoclonal antibodies in solution. The present study aimed to investigate the in-use stability of a residual monoclonal antibody solution after withdrawal of most of the filling volume of PF-06439535 (bevacizumab biosimilar), addressing the physical and chemical stability with respect to aggregation and fragmentation. Methods The stability of residual PF-06439535 solution (25 mg/mL) after withdrawal of 80% (12.8 mL) filling volume with a 20G needle was monitored over a light-protected storage period of 8 days at 2-8°C and 25°C with measurement time points at D0 (start of storage), D2, D4, and D8 (2, 4, and 8 days of storage after start, respectively). Unopened vials stored under the same conditions served as control. For this purpose, the analytical results from size exclusion chromatography, dynamic light scattering, and micro-flow imaging obtained after the individual measurement time points up to 8 days were compared with those obtained at D0 and with those obtained for unopened vials stored under the same conditions. Results No aggregation or ongoing fragmentation due to partial withdrawal of filling volume could be observed in the residual PF-06439535 solution. Moreover, no changes in the particle size distribution at D8 compared with the D0 values were identified upon storage at either 2-8°C or 25°C (both opened and unopened vials). The total concentration of particles ≥10 µm of all samples was <100 particles/mL. In addition, no variations in the pH values or in the visual appearance were detected over the whole study period in all samples at all storage conditions. Conclusions Consequently, residual PF-06439535 solution (25 mg/mL) in opened vials may be regarded as stable when stored light-protected over a period of 8 days in the refrigerator (2-8°C) or at 25°C. HOW THIS STUDY MIGHT AFFECT RESEARCH, PRACTICE OR POLICY⇒ There is a strong interest in clinical practice in the stability of residual PF-06439535 concentrate in opened vials. Based on the generated extended stability data obtained in the present study, the stability of PF-06439535 should be verified in more extensive studies.