Improved high-performance liquid chromatographic method to estimate aminosugars and its application to glycosaminoglycan determination in plasma and serum

An improved isocratic high-performance liquid chromatography (HPLC) method for the analysis of -(−)-fucose, -(+)-galactosamine, -(+)-glucosamine, -(+)-galactose, obtained by hydrolysis of glycosaminoglycans (GAGs) and -(+)-glucose and -(+)-mannose is described. The presence in circulation of GAGs, acid polysaccharide sequences of alternate monosaccharide units, aminosugar and uronic acid (galactose in keratan sulfate), has been measured in terms of their sugar components. To evaluate concentration of these circulating sugars we considered blood samples obtained from healthy humans. Plasma or serum was filtered through weak anion-exchange Ecteola-cellulose either untreated or after mild alkaline treatment. GAGs adhering to resin were recovered by salt elution, and desalted on Bio-Gel P-2 resin. GAG fractionation by charge was carried out on a strong anion exchanger. GAG composition was evaluated in terms of galactose and aminosugars, measured in HPLC by the proposed procedure using anion-exchange resin and pulsed amperometric detection. The mobile phase consisted of 0.02 M NaOH and elution was carried out at flow-rate of 1.0 ml/min. The amperometric detector was set as follows: t₁ (0.5 s), E₁ (+0.1 V); t₂ (0.09 s), E₂ (+0.6 V); t₃ (0.05 s), E₃ (−0.6 V). The analysis required 14 min. Calibration standard curves for the six analytes were linear from 0.25 to 40 μM. RSD values for intra- and inter-day variabilities were ≤5.3% at concentrations between 0.25 and 40 μM. Accuracy, expressed as percentage error, ranged from −16 to 14%. The method was specific and sensitive with quantitation limits of 1 pmol for -(−)-fucose, -galactosamine and -glucosamine, 3 pmol for -(+)-galactose and -(+)-glucose and 5 pmol for -(+)-mannose. The results of the assay showed higher GAG concentrations in serum than in plasma.     

An Oplegnathid beak (Osteichthyes: Perciformes) from the Early Miocene of Patagonia. Extirpation of several vertebrates from the southern Atlantic Ocean

The first record of the knifejaw family Oplegnathidae in the Atlantic Ocean and in South America is reported. It comes from the lowermost beds of the Early Miocene Gaiman Formation at the lower Río Chubut valley, central-eastern Patagonia. The family Oplegnathidae does not occur in the Atlantic today, but it was widespread in comparison to other knifejaw fishes, such as scarids and odacids. Several aquatic vertebrates were extirpated from the southern Atlantic Ocean in the Late Neogene. This record establishes a minimal age (Early Miocene) for the extirpation of the family Oplegnathidae in the Atlantic Ocean.     

Inhibition of human MDA-MB-231 breast cancer cell invasion by matrix metalloproteinase 3 involves degradation of plasminogen.

Matrix metalloproteinase (MMP)-3 inhibited human MDA-MB-231 breast cancer cell invasion through reconstituted basement membrane in vitro. Inhibition of invasion was dependent upon plasminogen and MMP-3 activation, was impaired by the peptide MMP-3 inhibitor Ac-Arg-Cys-Gly-Val-Pro-Asp-NH2 and was associated with: rapid MMP-3-mediated plasminogen degradation to microplasminogen and angiostatin-like fragments; the removal of single-chain urokinase plasminogen activator from MDA-MB-231 cell membranes; impaired membrane plasminogen association; reduced rate of tissue plasminogen activator (t-PA) and membrane-mediated plasminogen activation; and reduced laminin-degrading capacity. Purified human plasminogen lysine binding site-1 (kringles 1-3) exhibited a similar capacity to inhibit MDA-MB-231 invasion, impair t-PA and cell membrane-mediated plasminogen activation and impair laminin degradation by plasmin. Our data provide evidence that MMP-3 can inhibit breast tumour cell invasion in vitro by a mechanism involving plasminogen degradation to fragments that limit plasminogen activation and the degradation of laminin. This supports the hypothesis that MMP-3, under certain conditions, may protect against tumour invasion, which would help to explain why MMP-3 expression, associated with benign and early stage breast tumours, is frequently lost in advanced stage, aggressive, breast disease.     

Structure and reactivity of [Ru(2,3-Medpp)2Cl2]

The structure and reactivity of the complex [Ru(2,3-Medpp)₂Cl₂](PF₆)₂ (2,3-Medpp⁺=2-[2-(1-methylpyridiniumyl)]-3-(2-pyridyl)pyrazine) was investigated by X-ray diffraction (XRD), ¹H NMR, redox, and UV-Vis absorption measurements. X-ray analysis shows that crystals obtained from an acetonitrile-toluene solution contain the trans-Cl₂, trans-pyrazine isomeric form, while ¹H NMR and redox measurements on the main product of the synthetic workup indicate the presence of the trans-Cl₂, cis-pyrazine isomer. In the dark at 70 °C, the complex [Ru(2,3-Medpp)₂Cl₂]²⁺ reacts slowly in acetonitrile isomerizing to the cis-[Ru(2,3-Medpp)₂(CH₃CN)Cl]³⁺ species. Under ambient light in the presence of excess AgNO₃ the cis-[Ru(2,3-Medpp)₂(CH₃CN)₂]⁴⁺ species is obtained.     

Risk of mortality in a cohort of patients newly diagnosed with chronic atrial fibrillation

Objective  

To estimate the mortality rate of patients newly diagnosed with chronic atrial fibrillation (AF) and compare it with the one in the general population. To evaluate the role of co-morbidity and other factors on the risk of dying among AF patients.