New HPLC method for the determination of vitamins K , MK-4, and MK-7 in serum was evaluated and validated. This method is highly specific and sensitive with the low limit of quantification.
A novel application of the liquid chromatography method combined with the triple quadrupole tandem mass spectrometry method was developed for the quantification of vitamin K1 and two forms of vitamin K2 (menaquinone-4, menaquinone-7) in human serum. Total chromatography time for each run was 9 min. Time required for the sample pretreatment procedures was approximately 4 h. The coefficients of variation (CVs) of intra-assay were 10.4%, 3.2 % and 2.3% for vitamin K1 in three levels of quality control samples; were 14.3%, 3.2% and 6.7% for menaquinone-4; and were 11.1%, 6.0% and 7.0% for menaquinone-7. The inter-assay CVs were 12.8%, 11.3% and 7.4% for vitamin K1; were 15.2%, 9.2% and 8.7% for menaquinone-4; and were 13.2%,11.1% and 7.2% for menaquinone-7. No interference was found between K1, menaquinone-4 and menaquinone-7, nor any deuterated internal standards. This method was then used to determine reference values for Caucasian populations of central European origin. Samples were measured from 191 healthy volunteers (51.2 ± 16.2 years (mean ± SD)) and the values concerning K1 were 0.044–1.357 ng/mL for women and 0.030–1.214 ng/mL for men. The values for menaquinone-4 and menaquinone-7 did not exhibit any differences between women and men, and were 0.050–1.598 and 0.074–0.759 ng/mL, respectively.
Abstract:Background: The topical application of Vancomycin is increasingly being used in orthopedics because of the development of methicillin resistant bacteria. Consequently, resistance to Vancomycin has recently been on the rise. One possible explanation for this phenomenon could be the thermal degradation of Vancomycin to antibacterially inactive crystalline degradation products (CDP-1s). The aim of our in vitro experiment was to compare the creation and elution characteristics of CDP-1s and the active form of Vancomycin (factor B) released from bone grafts. Methods: CDP-1s and the factor B released from bone grafts into the buffer solution were measured using the high-performance liquid chromatography method at progressive intervals. Results: The factor B was released from bone grafts at the highest levels, typically on the fi rst day (618.8 mg/L). CDP-1 levels kept increasing until the end of measurement on day 15, when the concentration of CDP-1s (1280.7 mg/L) was much higher compared to that of factor B (217.5 mg/L).
Conclusions:We confi rmed the tendency of Vancomycin to convert to antimicrobially ineffective CDP-1s. Although Vancomycin is decomposed into crystalline degradation products, its active forms are released from bone grafts in suffi cient concentration for more than two keks (Tab. 3, Fig. 1, Ref. 15). Text in PDF www.elis.sk.
Infections of the musculoskeletal system present a serious problem with regard to the field of orthopedic and trauma medicine. The aim of the experiment described in this study was to develop a resorbable nanostructured composite layer with the controlled elution of antibiotics. The layer is composed of collagen, hydroxyapatite nanoparticles, and vancomycin hydrochloride (10 wt%). The stability of the collagen was enhanced by means of cross-linking. Four cross-linking agents were studied, namely an ethanol solution, a phosphate buffer solution of N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride/N-hydroxysuccinimide, genipin, and nordihydroguaiaretic acid. High performance liquid chromatography was used so as to characterize the in vitro release rates of the vancomycin and its crystalline degradation antibiotically inactive products over a 21-day period. The maximum concentration of the released active form of vancomycin (approximately 265 mg/L) exceeded the minimum inhibitory concentration up to an order of 17 times without triggering the burst releasing effect. At the end of the experiment, the minimum inhibitory concentration was exceeded by up to 6 times (approximately 100 mg/L). It was determined that the modification of collagen with hydroxyapatite nanoparticles does not negatively influence the sustainable release of vancomycin. The balance of vancomycin and its degradation products was observed after 14 days of incubation.
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