Determination of linezolid in human serum by reversed-phase high performance liquid chromatography with ultrafiolet and diode array detection

A high-performance liquid chromatographic (HPLC) method with UV and DAD detection for the quantitative determination of linezolid in human serum was developed in present work. Chromatography was carried out by reversed-phase technique on a RP-18 column with a mobile phase composed of 50 mM phosphate buffer and acetonitrile (76 : 26, v/v), adjusted to pH 3.5 with orthophosphoric acid. Serum samples were deproteinized with methanol centrifuged and then, the supernatant was analyzed using HPLC procedure. No interference was observed at the retention times of linezolid from blank serum or ten commonly used antibiotics. A concentration range from 0.50 to 30.0 g/mL was utilized to construct calibration curves. The lower limit of detection was determined to be 0.1 μg/mL of serum for both detectors. The lower limit of quantification of 0.25 μg/mL (CV = 2.6%) was established for determination using HPLC-UV and 0.5 μg/mL (CV = 5.42%) for HPLC-DAD. The recovery of linezolid was approximately 100%. Intra-day accuracy ranged from 0.97 to 12.63% and 0.74 to 10.85% for HPLC-UV and HPLC-DAD method, respectively. Intra-day precision was less than 4.69% for HPLC-UV and less than 5.42% for HPLC-DAD method. Tests confirmed the stability of linezolid in serum during three freeze-thaw cycles and during long-term storage of frozen serum for up to 6 weeks; in extracts it was stable in the HPLC autosampler over 24 h. Statistical analysis by Student's t-test showed no significant difference between the results obtained by these two methods. In summary, these methods will be used and adapted for infected patients in intensive care unit, to determine linezolid serum concentrations in order to know the pharmacokinetic profiles of linezolid

Determination of linezolid in human serum by reversed-phase high-performance liquid chromatography with ultraviolet and diode array detection

A high-performance liquid chromatographic (HPLC) method with UV and DAD detection for the quantitative determination of linezolid in human serum was developed in present work. Chromatography was carried out by reversed-phase technique on a RP-18 column with a mobile phase composed of 50 mM phosphate buffer and acetonitrile (76 : 26, v/v), adjusted to pH 3.5 with orthophosphoric acid. Serum samples were deproteinized with methanol centrifuged and then, the supernatant was analyzed using HPLC procedure. No interference was observed at the retention times of linezolid from blank serum or ten commonly used antibiotics. A concentration range from 0.50 to 30.0 g/mL was utilized to construct calibration curves. The lower limit of detection was determined to be 0.1 μg/mL of serum for both detectors. The lower limit of quantification of 0.25 μg/mL (CV = 2.6%) was established for determination using HPLC-UV and 0.5 μg/mL (CV = 5.42%) for HPLC-DAD. The recovery of linezolid was approximately 100%. Intra-day accuracy ranged from 0.97 to 12.63% and 0.74 to 10.85% for HPLC-UV and HPLC-DAD method, respectively. Intra-day precision was less than 4.69% for HPLC-UV and less than 5.42% for HPLC-DAD method. Tests confirmed the stability of linezolid in serum during three freeze-thaw cycles and during long-term storage of frozen serum for up to 6 weeks; in extracts it was stable in the HPLC autosampler over 24 h. Statistical analysis by Student's t-test showed no significant difference between the results obtained by these two methods. In summary, these methods will be used and adapted for infected patients in intensive care unit, to determine linezolid serum concentrations in order to know the pharmacokinetic profiles of linezolid

Proposed physiotherapeutic procedure in the treatment of breast cancer

Breast cancer is a global problem, causes many deaths worldwide, and the emergence of disability resulting from treatment. Physiotherapy is a 24/7 process. It is very often limited to just a few minutes of exercise a day, which is not enough. The aim of the work is to propose physiotherapeutic treatment in women after radical mastectomy and to present diagnostic problems caused by SARS-CoV-2 pandemics, which negatively affect cancer prevention

Validation of LC/MS/MS method for assessment of the "in vitro" activity of the selected rat cytochrome P450 isoenzymes : application to early drug metabolism screening

A sensitive and specific liquid chromatography/tandem mass spectrometry (LC/MS/MS) method for simultaneous determination of seven metabolites of CYP450 model substrates (acetaminophen, 4-hydroxytolbutamide, 4í-hydroxymephenytoin, 1-hydroxybufuralol, 6-hydroxychlorzoxazone, 1í- and 4í-hydroxymidazolam) in rat liver microsomes was developed. The assay used Kinetex analytical column and a gradient mobile phase consistent of acetonitrile and water with addition of 0.1% formic acid. The analysis was performed in selected reaction monitoring (SRM) mode both in positive and negative (for 6-hydroxychlorzoxazone) mode. The method was validated over the concentration ranges of 10-2000 ng/mL for 4í-hydroxymephenytoin and 4-hydroxytolbutamide, 50-2000 ng/mL for 1-hydroxybufuralol and 25-2000 ng/mL for the rest of the analytes. The intra- and inter-day precision (2-12%) and accuracy (93-119%) were within the limits set by the FDA and EMA guidelines. The developed method was successfully applied to assess the activity of selected CYP450 isoenzymes in rat liver microsomes after addition of ketoconazole

Validation of LC/MS/MS method for assessment of the "in vitro" activity of selected rat cytochrome P450 isoenzymes : application to early drug metabolism screening

A sensitive and specific liquid chromatography/tandem mass spectrometry (LC/MS/MS) method for simultaneous determination of seven metabolites of CYP450 model substrates (acetaminophen, 4-hydroxytolbutamide, 4'-hydroxymephenytoin, 1-hydroxybufuralol, 6-hydroxychlorzoxazone. 1'-and 4-hydroxymidazolam) in rat liver microsomes was developed. The assay used Kinetex analytical column and a gradient mobile phase consistent of acetonitrile and water with addition of 0.1\% formic acid. The analysis was performed in selected reaction monitoring (SRM) mode both in positive and negative (for 6-hydroxychlorzoxazone) mode. The method was validated over the concentration ranges of 10-2000 ng/mL for 4-hydroxymephenytoin and 4-hydroxytolbutamide, 50-2000 ng/mL for 1-hydroxybufuralol and 25-2000 ng/mL for the rest of the analytes. The intra- and inter-day precision (2-12%) and accuracy (93-119%) were within the limits set by the FDA and EMA guidelines. The developed method was successfully applied to assess the activity of selected CYP450 isoenzymes in rat liver microsomes after addition of ketoconazole

The process of physiotherapy in patients treated for colorectal cancer

Breast cancer is a global problem, causes many deaths worldwide, and the emergence of disability resulting from treatment. Physiotherapy is a 24/7 process. It is very often limited to just a few minutes of exercise a day, which is not enough. The aim of the work is to propose physiotherapeutic treatment in women after radical mastectomy and to present diagnostic problems caused by SARS-CoV-2 pandemics, which negatively affect cancer prevention

Truncating Variants in RFC1 in Cerebellar Ataxia, Neuropathy, and Vestibular Areflexia Syndrome

INTRODUCTION: Cerebellar Ataxia, Neuropathy and Vestibular Areflexia Syndrome (CANVAS) is an autosomal recessive neurodegenerative disease characterized by adult onset and slowly progressive sensory neuropathy, cerebellar dysfunction, and vestibular impairment. In most cases, the disease is caused by biallelic (AAGGG)n repeat expansions in the second intron of the Replication Factor Complex subunit 1 (RFC1). However, a small number of cases with typical CANVAS do not carry the common biallelic repeat expansion. The objective of this study was to expands the genotypic spectrum of CANVAS by identifying point mutations in RFC1 coding region associated with this condition. METHODS: Fifteen individuals diagnosed with CANVAS and carrying only one heterozygous (AAGGG)n expansion in RFC1 underwent WGS or WES to test for the presence of a second variant in RFC1 or other unrelated gene. To assess the impact of truncating variants on RFC1 expression we tested the level of RFC1 transcript and protein on patients' derived cell lines. RESULTS: We identified seven patients from five unrelated families with clinically defined CANVAS carrying a heterozygous (AAGGG)n expansion together with a second truncating variant in trans in RFC1, which included: c.1267C>T (p.Arg423Ter), c.1739_1740del (p.Lys580SerfsTer9), c.2191del (p.Gly731GlufsTer6) and c.2876del (p.Pro959GlnfsTer24). Patient fibroblasts containing the c.1267C>T (p.Arg423Ter) or c.2876del (p.Pro959GlnfsTer24) variants demonstrated nonsense-mediated mRNA decay and reduced RFC1 transcript and protein. DISCUSSION: Our report expands the genotype spectrum of RFC1 disease. Full RFC1 sequencing is recommended in cases affected by typical CANVAS and carrying monoallelic (AAGGG)n expansions. Also, it sheds further light on the pathogenesis of RFC1 CANVAS as it supports the existence of a loss of function mechanism underlying this complex neurodegenerative condition

Invasive plant species – threat to grasslands in river valleys

ABSTRACT. River valleys are areas of transition between aquatic and terrestrial communities, with com-plex biological structure. As ecotones they have high biodiversity as a result of the occurrence of species with different requirements according to soil moisture. They create ecological corridors, allowing migration of the organisms in human disturbed landscape. With these migration routes, species of foreign origin which spread to a new area also benefit. Numerous alien species are considered as invasive, and described as a threat to biodiversity due to strong competitive abilities. To describe the relationships between a num-ber of invasive species, biodiversity and size of a river, the vegetation of 750 m fragments of the Odra and Dobra river valleys on the area of the Wrocław city were analysed. The comparison of plant communities in the valley of a large, managed river (Odra) and its small tributary (Dobra) was carried out. The plant assemblages, occurring in study areas, determined the habitat conditions on the basis of Ellenberg’s indi-cator values (EIV’s), as well as Shannon-Wiener biodiversity index was defined. The designed sites differed according to Shannon-Wiener biodiversity index, as well as soil properties: moisture, reaction, and fertility. In the study side of the Odra river ruderal and scrub species were dominated, whereas in case of study site of the Dobra river – meadows and ruderal species. The invasive plant species occurring in the Odra valle

Wpływ metody renowacji, zastosowanej mieszanki i nawożenia na plon łąki na glebie piaszczystej

Background. Grasslands are considered as valuable for biodiversity maintaining and provides a range of ecosystem services. Optimal growth of renovated grasslands is influenced both by properly selected methods of renovation and subsequent balanced utilisation. The aim of the presented study was to assess the effect of renovation method, forage mixture and mineral fertilization on initial development, species composition and yield of forage grasslands established on sandy soil. Material and methods. The experiment was conducted at the Agricultural Experimental Station Swojec, which belongs to the Wroclaw University of Environmental and Life Science. Two renovation methods (overdrilling and full cultivation), three types of forage mixtures: pure grass (mixture I), grass with Trifolium repens (mixture II) and grass with T. pratense (mixture III), and four fertilization levels (0, 140 PK (40 P + 100 K), 220 NPK (80 N + 40 P +100 K), 300 NPK (160 N + 40 P + 100 K) were used as experimental factors. Results. The largest participation in species composition of the first harvest in the period between 2010–2012 was from Lolium perenne and Phleum pratense under both renovation methods. Tall grass species reached an average of 47%, short grasses 24%, and legumes 29% of DM. The overdrilling method significantly increased the plant yield when compared to the full cultivation method. The application of phosphorus and potassium (140 PK) gave the highest yield. The highest yield was obtained in plots where overdrilling of mixtures of forage grasses with T. pratense (mixture III) that were fertilized with only phosphorus and potassium. Conclusion. The results indicate, that the yield of the grassland is the higher, when overdrilling, as a method of sward renovation, addition of legumes to a grass mixture and the application of phosphorus-potassium fertilization was applied.Optymalne plonowanie odtwarzanej łąki jest zależne od odpowiednio dobranej metody renowacji oraz dalszego zrównoważonego użytkowania. Celem prezentowanych badań była ocena wpływu metody renowacji, zastosowanej mieszanki i nawożenia mineralnego na rozwój początkowy, skład gatunkowy i plon łąk na glebie piaszczystej. Doświadczenie było prowadzone w Zakładzie Doświadczalnym Swojec, należącym do Uniwersytetu Przyrodniczego we Wrocławiu. Jako czynniki doświadczenia zastosowano dwie metody renowacji runi (siew szczelinowy i pełną uprawę), trzy typy mieszanek pastewnych: złożoną tylko z traw (mieszanka I), trawy z dodatkiem Trifolium repens (mieszanka II) i trawy z T. pratense (mieszanka III) oraz trzy typy nawożenia mineralnego (0, 140 PK (40 P + 100 K), 220 NPK (80 N + 40 P + 100 K), 300 NPK (160 N + 40 P + 100 K). Największy udział w składzie gatunkowym w latach 2010–2012 miały Lolium perenne i Phleum pratense przy obydwu metodach renowacji. Trawy wysokie osiągały średnio 47%, trawy niskie 24% i rośliny motylkowe 29% suchej masy. Siew bezpośredni istotnie podnosił plon w porównaniu z zastosowaniem pełnej uprawy, także zastosowanie nawożenia fosforem i potasem (140 PK) przy braku nawożenia azotem wpływa na uzyskanie najwyższego plonu. Jeżeli analizowany jest kompleksowy wpływ zastosowanych czynników, najwyższy plon uzyskano na poletkach, gdzie zastosowano siew szczelinowy mieszanki traw z T. pratense (mieszanka III) oraz nawożenie fosforowo-potasowe przy braku nawożenia azotem