![]() ![]() The method is termed macrodilution when using a total volume in milliliters, or microdilution, if performed in microtiter plates using ≤500 µL per well. Broth dilution uses liquid culture medium containing increasing concentrations (typically a twofold dilution series) of the antimicrobial substance and inoculation with a defined number of bacterial cells. Agar and broth dilution are the most commonly used methods for determination of MIC of antimicrobial agents. Whereas the diffusion methods are mostly based on measurement of an inhibition zone on agar plate, dilution methods are based on determination of MIC via growth/no growth end-point. The most common methods used for research of antimicrobial activity of EOs include diffusion methods (agar disk-diffusion method, antimicrobial gradient method (Etest), agar well diffusion method) and dilution techniques (agar dilution and broth macro and microdilution method). ![]() The antimicrobial effect of essential oils (EOs) in vitro has been thoroughly studied in the past decades. Some components of EOs may bind to starch in MHB since the phenomenon seems to be selective and EO dependent, the use of MHB for comparison of antimicrobial properties of various EOs thus cannot be recommended. In the presence of oregano EO lag phase was also much less prolonged in MHB (by 6–17%) than in the other media (by 92–189%). This statistically significant difference was noted for all the pathogens studied ( Salmonella Enteritidis, Escherichia coli O157, Listeria monocytogenes, Staphylococcus aureus). The MIC values for oregano EO were significantly ( p < 0.001) lower in MHB than in highly nutritious media the median MICs were 616 µg/mL for MHB and 474 µg/mL for TSB and BHI. The median MICs for cinnamon essential oil (EO) obtained by broth dilution were 517, 465 and 517 µg/mL for Mueller–Hinton Broth (MHB), Tryptone Soya Broth (TSB) and Brain Heart Infusion (BHI), respectively. The aim of this study was to elucidate how much the MIC values obtained from various studies using different culture media are comparable. Peak bone mass (bone mineral content) in the trabecular substance of the lumbar vertebral column is higher in males than in females, and peak bone density is higher in young female adults than in young male adults.So far there is no internationally accepted, standardized method for MIC determination of natural substances such as essential oils (EOs). The normal trabecular bone mineral density is 150 mg/ml with a standard deviation of 20 mg/ml independent of age or gender until the beginning of puberty. For post-pubertal males, the mean Ca-HA content was 3.5 g, med 3.5, SD 0.5 g, and for post-pubertal females, the mean content was 2.8, med 2.7, SD 0.4 g. The Ca-HA content in the trabecular bone of the first lumbar vertebra was 1.1 (med 1.1, SD 0.5) g for prepubertal boys and 1.1 (0.9, 0.4) g for prepubertal girls. After puberty there was a significant difference (p < 0.001) between males and females: Mean density (male) 158.0, med 162.5, SD 24.0 mg/ml, mean density (female) 191.2, med 191.3, SD 17.7 mg/ml. We did not observe a difference between prepubertal boys and girls. Prepubertal boys had a mean bone density of 148.5 (median 150.1, standard deviation 15.4) mg/Ca-HA per ml bone, and prepubertal girls had a mean density of 149.5 (med 150.8, SD 23.5) mg/ml. ![]() We measured the trabecular bone density and the area and height of the vertebra and calculated the volume and content of calcium hydroxyapatite (Ca-HA) in the trabecular substance of the first lumbar vertebra. Scan parameters: Slice thickness 1 cm, 80 kV, 81 or 114 mAs. We used a Somatom Balance Scanner (Siemens, Erlangen) and the Siemens Osteo software. We also measured 17 healthy young adults (9 men, 8 women, mean ages 20 and 21 years). We performed quantitative computed tomography (QCT) on the first lumbar vertebra in 28 children and adolescents without diseases that may influence bone metabolism (15 boys, 13 girls, mean ages 11 and 8 years, respectively). The aim of this study was to assess bone density values in the trabecular substance of the lumbar vertebral column in children and young adults in Germany from infancy to the age of peak bone mass. ![]()
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