1,721,182 research outputs found
Development and Validation of a Liquid Chromatographic Method Useful for the Determination of Amino Acids in New and Commercial Alimentary Supplements
No full textIn this study, a new liquid chromatographic method with pre-column derivatization was developed and validated for the simultaneous quantification of acetylcarnitine taurinate, asparagine, potassium aspartate, asparagine and carnosine in new and commercial alimentary supplements. The effect of complex matrices was evaluated by the study of the amino acid derivatization reaction with 2,5-dimethyl-1H-pyrrole-3,4-dicarbaldehyde in placebo solutions (DPD). Experimental parameters affecting the derivatization and chromatographic separation were investigated. The reaction was carried out at room temperature for 10 min. The adducts were separated on a Synergi Hydro-RP 80 column using a mobile phase consisting of 11 mM aqueous tetrapropylammonium bromide (pH 3.5)/methanol by gradient elution conditions at a flow rate of 0.8 mL/min. UV absorbance detection was set at lambda = 320 nm. The validation parameters such as linearity, sensitivity, accuracy, precision, specificity and ruggedness were highly satisfactory. Linear responses were obtained by placebo solutions (determination coefficient a parts per thousand currency sign 0.9994). Intra-day precision (RSD) was a parts per thousand currency sign1.06 % for corrected peak area and a parts per thousand currency sign1.14 % for retention times (t (R)) without significant differences between intra- and inter-day data. Recovery studies showed good results for all the examined compounds (from 97.72 to 101.5 %) with RSD <= 1.30 %
The migration of lymphocytes and polymorphonuclear leukocytes across the endothelial wall of the absorbing peripheral lymphatic vessel
No full textMacrophage migration through the endothelium in the absorbing peripheral lymphatic vessel of the small intestine
No full text1,4-Anthraquinone: A new useful pre-column reagent for the determination of N-acetylcysteine and captopril in pharmaceuticals by high performance liquid chromatography
No full text1,4-Anthraquinone (ANQ) is proposed as a novel pre-column reagent for high performance liquid chromatography (HPLC) determination of N-acetylcysteine (NAC) and captopril (CAP) in pharmaceutical formulations. The derivatization reactions were carried out at room temperature: NAC at pH 8 for 1 min, while CAP at pH 7.5 for 20 min. Both reactions reached completeness at a reagent to thiol molar ratio of about 2.5. The synthesised derivatives were characterized by1H NMR and IR. The chromatographic separations were performed on a C18 Phenomenex Synergi Fusion 4 um (250 mm x mm I.D.) stainless steel column with detection at λ = 300 nm. The mobile phase consisted of methanol/triethylammonium (TEA) phosphate buffer (pH 3; 0.05 mol/L) 75:25 (v/v) at a flow-rate of 0.4 mL/min for NAC and 88:12 (v/v), at a flow-rate of 0.6 mL/min for CAP. The validation parameters (linearity, sensitivity, accuracy, precision, specificity and stability) were highly satisfactory. Linear response was observed (determination coefficient ≥0.9996). Detection limits were about 8 and 18 ng/mL for NAC and CAP, respectively. Intra-day precision (relative standard deviation, R.S.D.) was ≤1.58%, for thiol to internal standard (IS) peak area ratio and ≤0.33%, for thiol and IS retention times (tR), without significant differences between intra- and inter-day data. Thiol recovery studies were satisfactory (99.50%) with R.S.D. ≤0.56%. The results highlight the high sensitivity of the method and the remarkable reactivity and selectivity of the reagent towards the thiol function. The developed method is suitable for the quality control of both thiols in commercial products. The method can be applied in any analytical laboratory not requiring a sophisticated instrumentation
Polydeoxyribonucleotide (PDRN) promotes cyclobutane pyrimidine dimersrepair in UVB exposed dermal fibroblasts
No full textBackground: DNA is the main cellular chromophore for ultraviolet B (UVB). Its absorption leads to the generation of
typical photoproducts. The most frequent types (about 80%) are cyclobutane pyrimidine dimers (CPDs). Several studies
have suggested that treatment with deoxyribonucleosides can protect some cell types from DNA damage. The aim of this
work was to evaluate the ability of the polydeoxyribonucleotide (PDRN) to protect human dermal fibroblasts from UVBinduced
DNA damage.
Methods: Human dermal fibroblasts were irradiated with 600 mJ/cm(2) of UVB radiation. Cells were analyzed at
increasing time points from irradiation to study the recovery from UVB-induced DNA photodamage. Damage repair was
subsequently assessed by immunocytochemical analysis of CPDs levels and by measurement of p53 protein expression.
Results: The extracellular addition of 100 mu g/ml PDRN immediately after irradiation caused a strong activation of p53
protein in the first 24 h. This signal was accompanied by an increase in CPDs repair rates at early time points of
recovery.
Conclusions: The addition of PDRN to the culture medium supports CPDs repair probably providing a faster supply of
precursors for the deoxyribonucleotide triphosphates pool necessary to UVB-damaged cells. This condition could
promote the action of the salvage pathway, thereby accelerating DNA repair, but other inducible responses linked to
increased p53 expression could be involved
Effetto della luce laser 915 nm sulla proliferazione e differenzazione di osteoblasti e fibroblasti in vitro.
No full textA Novel Ultra-High Performance Liquid Chromatography Method for the Determination of Erdosteine, Related Impurities and Degradation Products in New Effervescent Tablets
No full textA novel and automated, stability-indicating, reversed phase ultra performance liquid chromatography (UPLC) method was developed and validated for the quantitative determination of erdosteine, its known impurities and two novel degradation products in a new pharmaceutical dosage form (effervescent tablets). The chromatographic separations were performed on a Waters Acquity UPLC HSS T3, 1.8 μm (2.1 mm × 150 mm, I.D.) stainless steel column. The mobile phase consisted of 0.1% TFA in water and methanol under gradient elution conditions, at a flow rate of 0.29 mL/min, for the assay and impurities analysis. UV detection was set at a wavelength of 238 nm. Erdosteine raw material, placebo and effervescent tablets were subjected to forced degradation. The new degradation products (labeled OX1 and OX2) were found after oxidative treatment and characterized by ultra performance liquid chromatography mass spectrometry. The validation parameters such as linearity, limit of detection (LOD) and quantification (LOQ), accuracy, precision, specificity and robustness were highly satisfactory for all analyzed compounds. LOD (0.020 and 0.011–0.385 μg/mL for erdosteine and impurities, respectively) and LOQ values show the high sensibility of the method. Specificity of the method was confirmed by testing the matrix components. The validated method demonstrated to be suitable for routine quality control purposes and for routine stability studies of erdosteine in effervescent formulations
Combinatorial co-expression of pheromone receptors, V2Rs
No full textBasal neurons of the vomeronasal organ of the mouse express a superfamily of about 120 pheromone receptors, named V2Rs, that are grouped in four families, A, B, C, and D, according to sequence homology. Family-A, -B, and -D V2Rs are expressed as one receptor gene per cell, but we previously reported their co-expression with family-C V2Rs. Here, we show that basal neurons can be further grouped according to the combinatorial expression of different V2Rs. Altogether, these findings suggest that in each basal neuron a transcriptional program is active for expressing a combination of two compatible receptors and for excluding, at the same time, the expression of all other V2Rs. Further analyses revealed non-random combinations of co-expression between family-C V2Rs and genes of the class Ib major histocompatibility complex. Thus, each basal neuron of the vomeronasal organ represents a highly qualified sensory unit for detecting very specific combinations of pheromonal cues
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