Effect of malvidin-3-monoglucoside on the browning of monomeric and dimeric flavanols

 The behaviour of (+)-catechin (cat), (–)-epicatechin (epi) and the procyanidin dimers B2 [epi-(4→8)-epi] and B3 [cat-(4→8)-cat], alone and in the presence of malvidin-3-monoglucoside, was studied in hydro-alcoholic solutions at pH 3.2 maintained at 32  °C for 120 days. Browning was observed both in the presence and absence of the anthocyanin, except in the solution containing only cat. The formation of pigments showing maximum absorption in the visible region of 440–460 nm was detected. The majority of these new pigments did not require the anthocyanin for their formation, but rather were derived directly from the flavanol. Nevertheless, some specific pigments showing similar spectra appeared in each of the solutions containing both a flavanol and the anthocyanin, and their production was attributed to a condensation process between the two latter compounds. The cat units showed a greater tendency to condense with the anthocyanin, while the epi units were more sensitive to chemical oxidation. The formation of pigments which showed maximum absorbance in the visible region around 530–545 nm, resulting from the condensation between the flavanol and the anthocyanin mediated by acetaldehyde, was also detected. As no acetaldehyde was added to the solutions, its presence was attributed to the oxidation of ethanol coupled to autoxidation of the catechol rings of the flavanols. Received: 29 December 1997 / Revised version: 23 March 1998     

Robot-aided neurorehabilitation: a robot for wrist rehabilitation.

In 1991, a novel robot, MIT-MANUS, was introduced to study the potential that robots might assist in and quantify the neuro-rehabilitation of motor function. MIT-MANUS proved an excellent tool for shoulder and elbow rehabilitation in stroke patients, showing in clinical trials a reduction of impairment in movements confined to the exercised joints. This successful proof of principle as to additional targeted and intensive movement treatment prompted a test of robot training examining other limb segments. This paper focuses on a robot for wrist rehabilitation designed to provide three rotational degrees-of-freedom. The first clinical trial of the device will enroll 200 stroke survivors. Ultimately 160 stroke survivors will train with both the proximal shoulder and elbow MIT-MANUS robot, as well as with the novel distal wrist robot, in addition to 40 stroke survivor controls. So far 52 stroke patients have completed the robot training (ongoing protocol). Here, we report on the initial results on 36 of these volunteers. These results demonstrate that further improvement should be expected by adding additional training to other limb segments.     

Proanthocyanidins in skins from different grape varieties

The proanthocyanidin composition of grape skins was studied and compared with that of grape seeds. Qualitative and quantitative differences in proanthocyanidin contents were observed between skins and seeds from the same variety. Grape seeds were found to have higher amounts of flavan-3-ol than skins; only procyanidins were found in the former, while in the skins prodelphinidins were also present, a predominance of (+)-catechin being found in their elemental flavan-3-ols.

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Proanthocyanidine in den Fruchtschalen verschiedener Traubensorten

Zusammenfassung Die Proanthocyanidine der Schale von Weinbeeren wurden analysiert und mit denen der Kerne verglichen. Innerhalb derselben Sorte wurden qualitative und quantitative Unterschiede zwischen den Gewebearten gefunden. Die Gehalte der Samen lagen generell am höchsten. In den Samen konnten nur Procyanidine nachgewiesen werden, während die Fruchtschalen auch Prodelphinidine enthielten. Insgesamt dominieren jedoch Catechin-Grundeinheiten.

     

Cymbopogon citratus leaves: Characterization of flavonoids by HPLC–PDA–ESI/MS/MS and an approach to their potential as a source of bioactive polyphenols

Leaves from cultivated Cymbopogon citratus were extracted with methanol, 80% aqueous ethanol and water (infusion and decoction) and the extracts were assessed for their antiradical capacity by 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay; the infusion extract exhibited the strongest activity. Tannins, phenolic acids (caffeic and p-coumaric acid derivatives) and flavone glycosides (apigenin and luteolin derivatives) were identified in three different fractions obtained from an essential oil-free infusion, and a correlation with their scavenger capacity for reactive oxygen species was studied. The tannin and flavonoid fractions were the most active against species involved in oxidative damage processes. In the flavonoid fraction, representing 6.1% of the extract, thirteen compounds (O- and C-glycosylflavones) were tentatively identified by high performance liquid chromatography, coupled to photodiode-array and electrospray ionization mass spectrometry detectors (HPLC–PDA–ESI/MS), nine of which were identified for the first time in this plant, all of them being C-glycosylflavones (mono-C-, di-C- and O,C-diglycosylflavones). The potential beneficial and protective value of the identified polyphenols for human health is discussed.     

Bidirectional connectivity via fish ladders in a large Neotropical river: Response to a comment

In a recent article, we described fitting electronic tags to the fish Prochilodus lineatus to document how a fishway connected aquatic habitats downstream and upstream of a major dam. Moreover, given that tagged fish remained upstream or downstream for periods extending months and years before returning to the fishway, and that observed patterns of passage were consistent with seasonal migratory cycles, and building on existing literature, we speculated that the fishway allows fish access to spawning habitats upstream and feeding habitats downstream. Our interpretation of the movement data resulted in several comments from Pelicice, Pompeu, and Agostinho (2020) and they outline various reasons by which, in their opinion, some of our conclusions may be mistaken. Their critique is threefold. First, they argue that the percentage of fish attracted into the fishway is too low to consider the fishway an effective link between the reservoir and the river downstream. We contend that without estimates of population size it is impossible to judge if 28% passage is “limited”; conceivably, the absolute number of fish passed may still be enough to maintain a viable population. Second, they assert that because receivers were located only in the fishway it is unknown if fish that used the fishway remained near the dam, or if they continued their migration. We counter with a brief literature review that documents P. lineatus migrating through reservoirs and spawning in tributaries. Third, they advocate for a broader conservation perspective and for additional research. We agree and, in the article, had already expressed this view that fishways are only a temporary fix and that we support their use only as an element of a broader environmental management package. We also agree with the need for more research but argue that procrastinating on conservation action may not be wise because we do not know if the research will be done, how long it will take, or what the cost may be of waiting.     

Anisotropic wetting of microstructured surfaces as a function of surface chemistry

In order to study the influence of surface chemistry on the wetting of structured surfaces, microstructures consisting of grooves or squares were produced via hot embossing of poly(ethylene-alt-tetrafluoroethylene) ETFE substrates. The structured substrates were modified with polymer brushes, thereby changing their surface functionality and wettability. Water droplets were most strongly pinned to the structure when the surface was moderately hydrophilic, as in the case of poly(4-vinylpyridine) (P4VP) or poly(vinyl(N-methyl-2-pyridone) (PVMP) brush-modified substrates. As a result, the droplet shape was determined by the features of the microstructure. The water contact angles (CA) were considerably higher than on flat surfaces and differed, in the most extreme case, by 37° when measured on grooved substrates, parallel and perpendicular to the grooves. On hydrophobic substrates (pristine ETFE), the same effects were observed but were much less pronounced. On very hydrophilic sampes (those modified with poly(N-methyl-vinylpyridinium) (QP4VP)), the microstructure had no influence on the drop shape. These findings are explained by significant differences in apparent and real contact angles at the relatively smooth edges of the embossed structures. Finally, the highly anisotropic grooved microstructure was combined with a gradient in polymer brush composition and wettability. In the case of a parallel alignment of the gradient direction to the grooves, the directed spreading of water droplets could be observed.     

Hepatitis C virus infection of salivary gland epithelial cells. Lack of evidence

BACKGROUND: Hepatitis C virus genome (HCV-RNA) has been detected in whole salivary gland tissue of chronically infected patients. However, contamination of the tissue by plasma or blood cells was not excluded by the previous reports. AIMS: To assess whether HCV infects the salivary gland epithelial cells in patients with chronic HCV liver disease. METHODS: Twenty unselected patients with chronic active hepatitis (11 cases) or active cirrhosis (nine cases) were examined. Serum and saliva samples were obtained from all patients, 12 of whom (seven, chronic active hepatitis; five, active cirrhosis) underwent salivary gland biopsy. PCR for HCV-RNA was performed on RNA extracted from serum, saliva and salivary gland epithelial cells collected by isokinetic gradient separation after trypsin digestion of whole salivary gland tissue. Saliva samples were also examined for the presence of secretory IgA anti-HCV by gel chromatography and ELISA testing. RESULTS: HCV-RNA was detected in all sera with titers ranging from 5.42 x 10(5) genome equivalents/ml to 123.2 x 10(5) genome equivalents/ml. Thirteen patients were infected with genotype 1b, four patients had genotype 1a, two patients had genotype 2a and one patient was unclassifiable. Low titer HCV-RNA (<2 x 10(5) genome equivalents/ml) was detected in 3/20 saliva samples (15%) from highly viremic patients infected with 1b genotype. RNA extracted from salivary gland epithelial cells consistently tested negative for HCV-RNA. In addition, all saliva specimens tested negative for secretory-IgA (S-IgA) anti-HCV, even after a 10-fold concentration of the samples. CONCLUSIONS: There was no evidence that HCV infects the salivary gland epithelial cells in our viremic patients with HCV chronic liver disease. Low level HCV-RNA in saliva is most probably due to virus spillover from blood.     

Optimizing Elliptic Filter Selectivity

The problem of determining the band-edge selectivity of elliptic filters and its optimization in filter design is considered. The band-edge selectivity is derived with respect to the -th order elliptic function. The selectivity formula embodies potential trade-offs in filter requirements for improving filter mangitude or delay response. Design examples are submitted in support of the theory. A simple proof describes the Chebyshev filter as an elliptic filter in the limit of infinite stopband corner frequency.