The Scottish model of vancomycin dosing and therapeutic drug monitoring improves both efficacy and safety of vancomycin therapy.

OBJECTIVE: Vancomycin therapeutic drug monitoring (TDM) is recommended for better treatment efficacy and safety. The Scottish Antimicrobial Prescribing Group model recommends weight-based loading dose, next 3-4 doses based on creatinine clearance and maintenance doses according to trough concentrations. METHODS: Retrospective cohort study of all adult patients treated with vancomycin before and after introducing the guideline in a large Czech hospital in 2015 compares the success rate in achieving recommended trough concentrations (10-20 mg/l) during first measurement and efficiency of maintaining these concentrations subsequently. Assessment of vancomycin related nephrotoxicity is included. RESULTS: In 2014, 74/163 (45.4 %) patients achieved recommended concentrations in the first measurement, compared to 101/160 (63.1 %) patients in 2016 (χ2; p = 0.001). Recommended trough concentrations in more than half of subsequent measurements were detected in 51/105 patients (48.6 %) in 2014 and in 80/117 patients (68.4 %) in 2016. Not a single level in subsequent measurements within the range was detected in 28 (26.7 %) cases in 2014 and in 10 (8.5 %) cases in 2016 (Mann-Whitney; p = 0.026). There was no difference in nephropathy occurrence (χ2; p = 0.286). CONCLUSION: The adopted Scottish model of vancomycin TDM resulted in very significantly higher achievement of recommended trough concentrations during first measurements and significantly more effective maintenance of subsequent concentrations, without increased nephrotoxicity. Key words: guideline - therapeutic drug monitoring - vancomycin.

Arbutin Content and Tyrosinase Activity of Bergenia Extracts.

The total arbutin content in the leaves of all the studied Bergenia plants (B. crassifolia, B. ciliata and B. x ornata) was determined. The highest values of the arbutin content have been established for B. crassifolia (58.9 ± 0.7 mg.g-¹ DW) and B. x ornata (51.0 ± 1.21 mg.g-¹ DW), and the lowest for B. ciliata (5.9 ± 0.6 mg.g-¹ DW). Arbutin concentration in the Bergenia leaves was the lowest in spring, in the autumn, on the contrary it increased. All the tested aqueous extracts caused a dose-dependent increase in diphenolase activity of fungal tyrosinase in a similar way as arbutin. On the other hand, all the ethanol extracts inhibited the diphenolase activity of tyrosinase.

Production of Podophyllotoxin by Plant Tissue Cultures of Juniperus virginiana.

Plant tissue cultures are a potential source of secondary metabolites. However, their production, when compared with intact plants, is usually lower. Phenylalanine, a biogenetic precursor of podophyllotoxin, was used to stimulate podophyllotoxin production in callus and suspension cultures of Juniperus virginiana L. The best phenylalanine effect on podophyllotoxin production was manifested in three-years-old callus cultures after a 21-days application of a 10 mmol/L concentration. A podophyllotoxin content of 0.15 mg/g DW was determined, which was about 400% higher in comparison with the control. The maximum content (0.48 mg/g DW) in newly derived suspension cultures (the 4' passage) was induced by 14-days application of a I mmol/L concentration; this was about 243% higher than the control. In one-year-old suspension cultures the highest podophyllotoxin content (0.56 mg/g DW) was recorded also after 14-days application of a I mmol/L concentration; this was about 211% higher than in the control cultures.

Plant Tissue Cultures of Juniperus virginiana.

Callus cultures of Juniperus virginiana L. (varieties 'Hetzii', 'Glauca', 'Grey Owl') were derived from fresh leaves of garden-grown trees on Schenk and Hildebrandt medium supplemented with 3.0 mg/L of α-naphthaleneacetic acid, 0.2 mg/L of kinetin and 15 mg/L of ascorbic acid. The growth characteristics of one-year-old and two-years-old cultures were determined. The maximum biomass in all varieties was achieved on the 35th day of the cultivation period. The increase in fresh weights of two-years-old callus cultures, when compared with one-year-old callus cultures, was as follows: variety 'Hetzii' by 25%, variety 'Glauca' by 29% and variety 'Grey Owl' by 49%. J. virginiana suspension cultures (varieties 'Hetzii', 'Glauca', 'Grey Owl') were derived from two-years-old callus cultures on Schenk and Hildebrandt medium supplemented with 3.0 mg/L of α-naphthaleneacetic acid, 0.2 mg/L of kinetin and 15 mg/L of ascorbic acid. The maximum biomass of all varieties was found on the 21st day of the cultivation period. These results indicate that a sub-cultivation interval of 35 days for callus cultures and of 21st days for suspension cultures can be recommended. The callus and suspension cultures of J. virginiana of the variety 'Glauca' have the best survivability and thus provide the most biomass.

Production of flavonoids and isoflavonoids in jasmonic acid-induced red clover suspension cultures.

Effect of exogenously applied jasmonic acid (JA) in combination with calcium and verapamil (a calcium channels blocker) on the production of flavonoids and isoflavonoids in suspension cultures of Trifolium pratense L. was investigated. The culture was cultivated in Gamborg medium with an addition of 2 mg.l(-1) of 2,4-dichlorophenoxyacetic acid and 2 mg.l(-1) of 6-benzylaminopurine, at the temperature of 25 °C, 16-hr light/8-hr dark period. The best effect of jasmonic acid on the production of flavonoids and isoflavonoids was manifested after a 24-hour application of the 50 µmol.l(-1) concentration. The maximum production of JA-induced suspension culture was observed when cells were treated with a high level of calcium (10 mmol.l(-1)). The addition of all concentrations of verapamil to JA-induced suspension culture decreased production of flavonoids and isoflavonoids.

New synthetic pyridine derivate as potential elicitor in production of isoflavonoids and flavonoids in Trifolium pratense L. suspension culture.

The production of secondary metabolites in Trifolium pratense L. suspension culture of the family of legume plants (Fabaceae) is low, and therefore there was an attempt to increase it by elicitation. New synthetic substance, 2-(2-fluoro-6-nitrobenzylsulfanyl)pyridine-4-carbothioamide, was tested as elicitor--a substance that showed the best elicitation effect after 48-hour application of 1 µmol L⁻¹ concentration. Maximum contents of genistin (11.60 mg g⁻¹ DW), daidzein (8.31 mg g⁻¹ DW), and genistein (1.50 mg g⁻¹ DW) were recorded, and the production of these isoflavonoids thus significantly increased, when compared with the control, by 152%, 151%, and 400%. The maximum content of flavonoids (5.78 mg g⁻¹ DW) and the increase in the production by 142%, when compared with the control, were induced by 6-hour application of 100 µmol L⁻¹ concentration. The tested substance showed to be an effective elicitor of phenylpropane metabolism.

Effects of zinc and cadmium ions on cell growth and production of coumarins in cell suspension cultures of Angelica archangelica L.

The plant cell may respond to the excess of heavy metals in its environment by various mechanisms, including enhanced biosynthesis of secondary metabolites. In this study, zinc (0 to 1500 µM) and cadmium ions (0 to 100 µM) were tested as potential elicitors of the production of coumarins in angelica cell suspension cultures. In addition, the toxicity of both metals was assessed by evaluating their effect on cell growth (characterized by fresh and dry biomass at the end of a two-week subculture). It has been found that fresh biomass was not influenced up to zinc concentrations of 150 and 300 µM in the dark-grown and light-grown cultures, resp. Then it declined with an increasing zinc level. Zinc at 1500 µM diminished it by 54% and 24% in the dark-grown and light-grown cultures, resp. Dry biomass was influenced in a similar way. Zinc at 1500 µM reduced dry cell weight by 30% and 20% in cultures in the dark and in the light, resp. Cadmium ions did not affect fresh and dry weights of cells up to concentrations of 10 µM and 50 µM in cultures in the dark and in the light, resp. Toxic concentrations of cadmium are by an order of magnitude lower than those of zinc. Cadmium at 50 µM reduced fresh and dry cell weights by 66% and 59%, resp., in the dark-grown cultures. Cadmium at 100 µM caused a decrease in fresh and dry biomass by 40% and 44%, resp., in the light-grown cultures. Neither zinc nor cadmium improved production of coumarins.

Seasonal variation in total phenolic and flavonoid contents and DPPH scavenging activity of Bellis perennis L. flowers.

Variations in total phenolic and flavonoid contents as well as antioxidant activity of Bellis perennis (common daisy) flowers were investigated. The flowers were collected monthly (from March to October, i.e., during the usual flowering season of the plant) at three localities in three different years. Total flavonoids were determined spectrophotometrically by two methods: by formation of a complex with aluminium chloride after acidic hydrolysis of flower extracts (method 1) and by reaction with boric and oxalic acids in extracts without their modification (method 2). Total phenolics were determined spectrophotometrically using the Folin-Ciocalteu reagent. The antioxidant activity was determined spectrophotometrically by a 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay. The contents of flavonoids varied from 0.31 to 0.44 mg quercetin equivalent/100 mg dry weight (method 1) and from 1.37 to 2.20 mg pigenin-7-glucoside equivalent/100 mg dry weight (method 2). Total phenolics ranged from 2.81 to 3.57 mg gallic acid equivalent/100 mg dry weight. The antioxidant activity expressed as IC(50) values varied from 66.03 to 89.27 µg/mL; it is about 50, 30, 20, and 10 times lower as compared with quercetin, ascorbic acid, Trolox®, and butylhydroxytoluene, respectively, and about five times higher in comparison with apigenin-7-glucoside. There is a significant correlation between antioxidant activity and total phenolics. No correlation between total flavonoid contents and antioxidant activity was observed. Contents of phenolics and flavonoids as well as antioxidant activity of daisy flowers vary to a relatively small extent during the year and are not dependant on the time of collection. Thus, the flowers possess comparable quality as to these characteristics over the whole flowering season of Bellis perennis. Effects of environmental factors on the amounts of secondary metabolites in plants are also discussed.