Structural investigations on betacyanin pigments by LC NMR and 2D NMR spectroscopy

Four betacyanin pigments were analysed by LC NMR and subjected to extensive NMR characterisation after isolation. Previously, low pH values were applied for NMR investigations of betalains resulting in rapid degradation of the purified substances thus preventing extensive NMR studies. Consequently, up to now only one single (13)C NMR spectrum of a betalain pigment, namely that of neobetanin (=14,15-dehydrobetanin), was available. Because of its sufficient stability under highly acidic conditions otherwise detrimental for betacyanins, this pigment remained an exemption. Since betalains are most stable in the pH range of 5-7, a new solvent system has been developed allowing improved data acquisition through improved pigment stability at near neutral pH. Thus, not only (1)H, but for the first time also partial (13)C data of betanin, isobetanin, phyllocactin and hylocerenin isolated from red-purple pitaya [Hylocereus polyrhizus (Weber) Britton & Rose, Cactaceae] could be indirectly obtained by gHSQC- and gHMQC-NMR experiments.     

The IGF1 small dog haplotype is derived from Middle Eastern grey wolves: a closer look at statistics,sampling, and the alleged Middle Eastern origin of small dogs

This paper is a response to Gray MM, Sutter NB, Ostrander EA, Wayne RK: The IGF1 small dog haplotype is derived from Middle Eastern grey wolves. BMC Biology 2010, 8:16.     

An overview of malaria transmission from the perspective of Amazon Anopheles vectors

In the Americas, areas with a high risk of malaria transmission are mainly located in the Amazon Forest, which extends across nine countries. One keystone step to understanding the Plasmodium life cycle in Anopheles species from the Amazon Region is to obtain experimentally infected mosquito vectors. Several attempts to colonise Ano- pheles species have been conducted, but with only short-lived success or no success at all. In this review, we review the literature on malaria transmission from the perspective of its Amazon vectors. Currently, it is possible to develop experimental Plasmodium vivax infection of the colonised and field-captured vectors in laboratories located close to Amazonian endemic areas. We are also reviewing studies related to the immune response to P. vivax infection of Anopheles aquasalis, a coastal mosquito species. Finally, we discuss the importance of the modulation of Plasmodium infection by the vector microbiota and also consider the anopheline genomes. The establishment of experimental mosquito infections with Plasmodium falciparum, Plasmodium yoelii and Plasmodium berghei parasites that could provide interesting models for studying malaria in the Amazonian scenario is important. Understanding the molecular mechanisms involved in the development of the parasites in New World vectors is crucial in order to better determine the interaction process and vectorial competence.     

An IGF-I promoter polymorphism modifies the relationships between birth weight and risk factors for cardiovascular disease and diabetes at age 36

BACKGROUND: Biochemical testing for pheochromocytoma by measurement of fractionated plasma metanephrines is limited by false positive rates of up to 18% in people without known genetic predisposition to the disease. The plasma normetanephrine fraction is responsible for most false positives and plasma normetanephrine increases with age. The objective of this study was to determine if we could improve the specificity of fractionated plasma measurements, by statistically adjusting for age. METHODS: An age-adjusted metanephrine score was derived using logistic regression from 343 subjects (including 33 people with pheochromocytoma) who underwent fractionated plasma metanephrine measurements as part of investigations for suspected pheochromocytoma at Mayo Clinic Rochester (derivation set). The performance of the age-adjusted score was validated in a dataset of 158 subjects (including patients 23 with pheochromocytoma) that underwent measurements of fractionated plasma metanephrines at Mayo Clinic the following year (validation dataset). None of the participants in the validation dataset had known genetic predisposition to pheochromocytoma. RESULTS: The sensitivity of the age-adjusted metanephrine score was the same as that of traditional interpretation of fractionated plasma metanephrine measurements, yielding a sensitivity of 100% (23/23, 95% confidence interval [CI] 85.7%, 100%). However, the false positive rate with traditional interpretation of fractionated plasma metanephrine measurements was 16.3% (22/135, 95% CI, 11.0%, 23.4%) and that of the age-adjusted score was significantly lower at 3.0% (4/135, 95% CI, 1.2%, 7.4%) (p < 0.001 using McNemar's test). CONCLUSION: An adjustment for age in the interpretation of results of fractionated plasma metanephrines may significantly decrease false positives when using this test to exclude sporadic pheochromocytoma. Such improvements in false positive rate may result in savings of expenditures related to confirmatory imaging.     

Elevated levels of fibrinogen-derived endogenous citrullinated peptides in synovial fluid of rheumatoid arthritis patients

Introduction

Rheumatoid arthritis (RA) is an autoimmune disease characterized by inflammation of the joints and the presence of autoantibodies directed against proteins containing the non-standard arginine-derived amino acid citrulline. The protein fibrinogen, which has an essential role in blood clotting, is one of the most prominent citrullinated autoantigens in RA, particularly because it can be found in the inflamed tissue of affected joints. Here, we set out to analyze the presence of citrullinated endogenous peptides in the synovial fluid of RA and arthritic control patients.

Methods

Endogenous peptides were isolated from the synovial fluid of RA patients and controls by filtration and solid phase extraction. The peptides were identified and quantified using high-resolution liquid chromatography-mass spectrometry.

Results

Our data reveal that the synovial fluid of RA patients contains soluble endogenous peptides, derived from fibrinogen, containing significant amounts of citrulline residues and, in some cases, also phosphorylated serine. Several citrullinated peptides are found to be more abundantly present in the synovial fluid of RA patients compared to patients suffering from other inflammatory diseases affecting the joints.

Conclusions

The increased presence of citrullinated peptides in RA patients points toward a possible specific role of these peptides in the immune response at the basis of the recognition of citrullinated peptides and proteins by RA patient autoantibodies.     

An approach to the chemotaxonomic differentiation of two European dog's mercury species: Mercurialis annua L. and M. perennis L

Mercurialis annua and M. perennis are medicinal plants used in complementary medicine. In the present work, analytical methods to allow a chemotaxonomic differentiation of M. annua and M. perennis by means of chemical marker compounds were established. In addition to previously published compounds, the exclusive presence of pyridine-3-carbonitrile and nicotinamide in CH(2) Cl(2) extracts obtained from the herbal parts of M. annua was demonstrated by GC/MS. Notably, pyridine-3-carbonitrile was identified for the first time as a natural product. Further chromatographic separation of the CH(2) Cl(2) extracts via polyamide yielded a MeOH fraction exhibiting a broad spectrum of side-chain saturated n-alkylresorcinols. While the n-alkylresorcinol pattern was similar for both plant species, some specific differences were observed for particular n-alkylresorcinol homologs. Finally, the investigation of H(2) O extracts by LC/MS/MS revealed the presence of depside constituents. Whereas, in M. perennis, a mixture of mercurialis acid (=(2R)-[(E)-caffeoyl]-2-oxoglutarate) and phaselic acid (=(E)-caffeoyl-2-malate) could be detected, in M. annua solely phaselic acid was found. By comparison with synthesized enantiomerically pure (2R)- and (2S)-phaselic acids, the configuration of the depside could be determined as (2S) in M. annua and as (2R) in M. perennis.     

Lipid and Phenolic Constituents from Seeds of Hypericum perforatum L. and Hypericum tetrapterum Fr. and their Antioxidant Activity

Seeds of Hypericum perforatum and H. tetrapterum were extracted with dichloromethane and methanol and investigated by chromatographic and mass spectrometric methods. Both species yielded a fatty oil fraction amounting to 30.5% and 18.0% of the seed weight, respectively. Linoleic acid (C18:2n‐6) was shown to be the predominant fatty acid constituent. Moreover, xanthone derivatives, i.e. tetrahydroxyxanthones (THX), xanthone‐glycosides and xanthone‐sulfonates, were assigned in methanolic extracts. For structure elucidation, one representative xanthone, namely 1,3,6,7‐THX, was synthesized and analyzed via HPLC‐DAD/MSⁿ and GC/MS. Total THX contents were quantitated applying a validated HPLC‐DAD method, resulting in 1.25 g/kg (H. perforatum) and 0.27 g/kg (H. tetrapterum), respectively. Moreover, the free radical scavenging capacity of the methanol extracts was tested using the DPPH antioxidant assay. Both, H. perforatum (IC₅₀ = 8.7 mg/l) and 1,3,6,7‐THX (IC₅₀ = 3.0 mg/l), exhibited good DPPH free radical scavenging activity compared to Trolox (IC₅₀ = 6.6 mg/l).