Different physicochemical interactions between varietal wines and human saliva: Correspondence with astringency

Astringency corresponds to the sensation of dryness and roughness that is experienced in the oral cavity in association with the interaction between salivary proteins and food polyphenols. In this study, the phenolic composition of seven varietal wines, the intensity of astringency they evoke and the physicochemical reactivity of these wines with whole human saliva were evaluated. Phenolic composition of wines was characterized by spectrophotometry and HPLC chromatography. Intensity of astringency was evaluated by trained sensory panels. Saliva from a single volunteer subject was used to assess wine-saliva interactions. To this end, binary mixtures were produced at different v/v wine/saliva ratios and each of them assayed for the ability of the salivary protein to diffuse on a cellulose membrane (diffusion test) and to remain in solution (precipitation test). Physicochemical reactivities between wine components and the protein fraction of saliva were contrasted against the astringency and the phenolic profile of each varietal wine. The study supports the view that astringency depends on physicochemical interactions between two complex matrices -wine and saliva- and not between some of their particular components.

Wines in contact with oak wood: the impact of the variety (Carménère and Cabernet Sauvignon), format (barrels, chips and staves), and aging time on the phenolic composition

BACKGROUND

This study characterized the flavonoid and nonflavonoid phenolic composition of Carménère and Cabernet Sauvignon wines that were in contact with barrels, chips, and staves during a 12 month aging period. The wines were evaluated by spectrophotometric (for total phenols, anthocyanins and tannins, colorant intensity, hue, CIELab parameters, and fractionation into mono-, oligo-, and polymers of proanthocyanidins) and high-performance liquid chromatography diode array detection analyses (for ellagitannins, gallotannins, anthocyanins, and low molecular weight phenols).

RESULTS

Wines in contact with oak wood presented a strong enrichment with nonflavonoid compounds, such as caffeic, gallic, and ellagic acids and ellagitannins. Wines in contact with staves stood out for the increased presence of total phenols, vanillic acid, and higher color intensity, whereas wines aged in contact with chips showed large contents of proanthocyanidin gallates. Wines aged in barrels exhibited high contents of ellagitannins and ethyl gallates. The effect of wood on the phenolic composition was mostly associated with the original and intrinsic characteristics of each grape variety.

CONCLUSION

Extraction of phenolic compounds from oak wood during wine aging is closely related to the wood format, grape variety (Carménère or Cabernet Sauvignon), and aging time. The final effect of wood on wine would be related not just to the transference of polyphenols from wood, but also to structural modifications of grape polyphenols. © 2018 Society of Chemical Industry.

Ahmed glaucoma drainage implant surgery in the management of refractory uveitic glaucoma: Long-term follow up

OBJECTIVE

To examine the long-term efficacy, safety and complications of Ahmed glaucoma drainage implant surgery in patients with refractory uveitic glaucoma.

METHODS

Retrospective review of consecutive cases of patients with refractory uveitic glaucoma who underwent Ahmed glaucoma drainage implant surgery between 2004-2014. Demographic characteristics of the study population, visual acuity, intraocular pressure (IOP), number of antiglaucoma medications and operative and postoperative complications were recorded. Complete success was defined as IOP≥5 and ≤18mmHg without any medication, as qualified success if IOP≤18mmHg with one or more medications. Patients with less than 12 months of follow-up were excluded.

RESULTS

21 patients (26 eyes) were included. The mean postoperative follow-up was 53.5±31 months. Eight eyes (30%) had at least one previously failed glaucoma surgery. IOP was reduced from a mean of 30.0mmHg to 14.0mmHg at the last follow-up visit (P<.001). The number of IOP-lowering medications was reduced from a median of 2.9 preoperatively to 1.1 at the last follow-up (P<.001). Overall, 7 eyes (27%) were classified as complete success, 13 eyes (50%) were considered as qualified success, and 6 eyes (23%) met the criteria for failure. The most common postoperative complication was hypertensive phase in 12 eyes (46%). Kaplan-Meier life-table analysis showed a cumulative probability of success after Ahmed glaucoma valve implantation of 65% at 84 months.

CONCLUSIONS

Ahmed glaucoma drainage implant surgery may be considered a long-term effective and safety surgical option for patients with refractory uveitic glaucoma.

Algorithm approach for revision surgery following late-onset bleb complications after trabeculectomy: long-term follow-up

Purpose:

The aim of this study was to introduce a reproducible algorithm for the surgical management of late-onset (>2 months) bleb complications after trabeculectomy with mitomycin C.

Methods:

We performed a retrospective review of eyes treated using a reproducible algorithm approach by a single surgeon for the surgical management of late-onset bleb complications from July 2006 to April 2014. Exclusion criteria were bleb revision with less than 3 months of follow-up or bleb revision combined with other glaucoma procedures at the time of surgery. Success was evaluated using the Kaplan-Meier survival method and defined as achieving all of the following criteria: primary surgery indication resolved, no additional surgery required for decreasing the intraocular pressure (IOP), and IOP of ≥6 mmHg and ≤18 mmHg.

Results:

Twenty-three eyes from 20 patients were evaluated. Indications for bleb revision were hypotonic maculopathy (47.8%), bleb leak (30.4%), and dysesthetic bleb (21.7%). The overall primary outcome success rate calculated using the Kaplan-Meier survival method was 65.2% at 48 months. When the IOP target was changed to ≤15 mmHg, the bleb survival rate was 47.8% at 48 months. At the most recent postoperative visit, 95.7% of eyes had an IOP of ≤15 mmHg and 56.5% were being treated with an average of one medication per eye. One eye (4.3%) required a second bleb revision for persistent hypotony and two eyes required glaucoma surgery to reduce IOP during follow-up.

Conclusions:

An algorithm approach for the surgical management of late-onset bleb complications with a success rate similar to those reported in specialized literature is proposed. Randomized trials are needed to confirm the best surgical approach.

Wine pH Prevails over Buffering Capacity of Human Saliva

Wine is an acidic beverage; its pH (2.9-3.8) is critically important to its organoleptic properties. During degustation, wine interacts with <1 mL of mouth saliva, the pH of which is near 7.0. This is buffered predominantly by the carbonate/bicarbonate pair (pK_a = 6.1). Few data are available on whether the buffering capacity of saliva may alter the pH of wine and thus its sensorial properties. In this study both in vitro and in vivo approaches were conducted to measure pH in mixtures of representative red and white wines with human saliva. Continuous additions of microvolumes of either wine to a definite volume (3 mL) of saliva in vitro resulted in a progressive and steep decline in the pH of the wine/saliva mixture. Thus, a few microliters of either wine (<0.27 mL) was sufficient to reduce the pH of saliva by 1 pH unit. Further additions of wine to saliva lowered the pH to that of the corresponding wine. In the in vivo assay, definite volumes (1.5-18 mL) of either wine were mixed for 15 s with the mouth saliva of individual healthy subjects before pH determination in the expectorated wine/saliva mixtures. Compared to saliva, pronounced decreases in pH were observed, thus approaching the pH of wine even with the smallest volume of wine in the assay. Altogether, these results demonstrate that the buffering capacity of wine prevails over that of saliva and that during degustation the pH of the wine/saliva mixture in the mouth is, at least temporarily, that of the corresponding wine.

Proteomic Analysis of Exosomes and Exosome-Free Conditioned Media From Human Osteosarcoma Cell Lines Reveals Secretion of Proteins Related to Tumor Progression

Osteosarcomas are the most prevalent bone tumors in pediatric patients, but can also occur later in life. Bone tumors have the potential to metastasize to lung and occasionally other vital organs. To understand how osteosarcoma cells interact with their micro-environment to support bone tumor progression and metastasis, we analyzed secreted proteins and exosomes from three human osteosarcoma cell lines. Exosome isolation was validated by transmission electron microscopy (TEM) and immuno-blotting for characteristic biomarkers (CD63, CD9, and CD81). Exosomal and soluble proteins (less than 100 kDa) were identified by mass spectrometry analysis using nanoLC-MS/MS and classified by functional gene ontology clustering. We identified a secretome set of >3,000 proteins for both fractions, and detected proteins that are either common or unique among the three osteosarcoma cell lines. Protein ontology comparison of proteomes from exosomes and exosome-free fractions revealed differences in the enrichment of functional categories associated with different biological processes, including those related to tumor progression (i.e., angiogenesis, cell adhesion, and cell migration). The secretome characteristics of osteosarcoma cells are consistent with the pathological properties of tumor cells with metastatic potential. J. Cell. Biochem. 118: 351-360, 2017. © 2016 Wiley Periodicals, Inc.

Phenolic composition and antioxidant capacity of pomaces from four grape varieties (Vitis vinifera L.)

BACKGROUND

Phenolic compounds are widely distributed secondary metabolites in plants usually conferring them with unique taste, flavour and health-promoting properties. In fruits of Vitis vinifera L., phenolic composition is highly dependent on grape variety. Differential extraction of these compounds from grapes during winemaking is critically associated with wine quality. By-products of winemaking, such as grape pomace, can contain significant amounts of polyphenols. However, information concerning the varietal effect on wine grape pomace is scarce. In this study, pomaces from Sauvignon Blanc (SB), Chardonnay (CH), Cabernet Sauvignon (CS) and Carménère (CA) grape varieties were characterized spectroscopically and by HPLC-DAD analysis.

RESULTS

White grape pomaces (SB and CH) presented higher antioxidant capacities and higher contents of total phenols and total proanthocyanidins compared with red grape pomaces (CS and CA), whereas the latter showed much higher anthocyanin levels and colour intensities. Concentrations of monomeric proanthocyanidins and low-molecular-weight phenols in the four grape pomace varieties were significantly different.

CONCLUSION

Grape pomaces from four varieties showed high but diverse contents of polyphenols and antioxidant capacities. Thus grape pomaces represent an important potential source of polyphenols, which could be useful for nutritional and/or pharmacological purposes.

Chemical and sensory effects of storing sauvignon Blanc wine in colored bottles under artificial light

The chemical and sensory effects of storing Sauvignon Blanc in colored bottles and exposing them to artificial light were examined. The colors of the bottles chosen were Dead Leaf Green, Antique Green, Amber, and Flint. The light was provided by fluorescent tubes with a regime of 16 h of exposure during 8 months of storage. The results indicated that the wine's chemical composition was affected by the type of bottle used. The Flint bottle presented the lowest concentration of total phenols. Yellow coloration was not dependent on the bottle color, as the wine in darker bottles (Amber, Antique Green, and Dead Leaf Green) had considerably more yellow color development than the wine in clear bottles. With regard to the sensory analyses performed, a trend showing an increase in color intensity and a decrease in overall aromas depending on the bottle color was observed. The wine's aromatic description changed significantly during its storage under artificial light conditions, demonstrating a decrease in vegetal aromas and an increase in citrus and tropical flavors that was dependent on the bottle color.

Dynamics of tear fluid desiccation on a glass surface: a contribution to tear quality assessment

BACKGROUND

Fern-like crystalloids form when a microvolume of tear is allowed to dry out at ambient conditions on a glass surface. Presence of crystalloids in tear "microdesiccates" is used to evaluate patients with Dry-Eye disease. This study aims to examine morphologically the desiccation process of normal tear fluid and to identify changes associated with accelerated tear evaporation. Tear microdesiccates from healthy (Non-Dry Eye) and Dry Eye subjects were produced at ambient conditions. Microdesiccate formation was monitored continuously by dark-field video microscopy. Additionally, accelerated desiccation of tear samples from healthy subjects was conducted under controlled experimental conditions. Particular morphological domains of tear microdesiccates and their progressive appearance during desiccation were compared.

RESULTS

In normal tear microdesiccates, four distinctive morphological domains (zones I, II, III and transition band) were recognized. Stepwise formation of those domains is now described. Experimentally accelerated desiccation resulted in marked changes in some of those zones, particularly involving either disappearance or size reduction of fern-like crystalloids of zones II and III. Tear microdesiccates from Dry Eye subjects may also display those differences and be the expression of a more synchronous formation of microdesiccate domains.

CONCLUSION

Morphological characteristics of tear microdesiccates can provide insights into the relative rate of tear evaporation.

Phenolic composition and mouthfeel characteristics resulting from blending Chilean red wines

BACKGROUND

The blending of wine is a common practice in winemaking to improve certain characteristics that are appreciated by consumers. The use of some cultivars may contribute phenolic compounds that modify certain characteristics in blended wines, particularly those related to mouthfeel. The aim of this work was to study the effect of Carménère, Merlot and Cabernet Franc on the phenolic composition, proanthocyanidin profile and mouthfeel characteristics of Cabernet Sauvignon blends.

RESULTS

Significant differences in chemical composition were observed among the monovarietal wines. Separation using Sep-Pak C₁₈ cartridges revealed differences in the concentration but not in the proportion of various proanthocyanidins. Blending reduced polyphenol concentration differences among the various monovarietal wines. Although no major overall differences were observed after blending the monovarietal wines, this oenological practice produced clear differences in mouthfeel characteristics in such a way that the quality of the perceived astringency was different.

CONCLUSION

This study showed that the use of a particular wine variety (Cabernet Sauvignon) in a higher proportion in wine blending produced blends that were less differentiable from the monovarietal wine, owing to a suppression effect, producing an apparent standardization of the wines regarding chemical composition.

Effect of inert gas and prefermentative treatment with polyvinylpolypyrrolidone on the phenolic composition of Chilean Sauvignon blanc wines

BACKGROUND

Sauvignon blanc wines are produced under a wide variety of winemaking conditions, some of which include different fruit-ripening levels, cold soaks and the use of fining agents and inert gases. Anecdotal evidence suggests that sensory variations among these wines may have to do with their phenolic composition and concentration. Therefore the aim of this work was to study the effects of different winemaking conditions typically used in Chile on the phenolic composition and concentration of Sauvignon blanc wines.

RESULTS

The use of an inert gas (CO2) in winemaking produced differences in the proportion of proanthocyanidin fractions. A higher concentration of flavan-3-ol monomers resulted from winemaking in the presence of inert gas. This condition also produced a higher content of total phenols and low-molecular-weight phenolic compounds. Low doses of polyvinylpolypyrrolidone (PVPP) in the prefermentative treatments produced wines with a higher content of phenolic compounds. Under these conditions a higher content of polymeric proanthocyanidins was observed.

CONCLUSION

Different winemaking conditions modified the concentration and proportion of proanthocyanidin fractions and the global phenolic composition of the resulting white wines. This should be taken into account by the wineries producing these wines.

Phenolic compositions of grapes and wines from cultivar cAbernet Sauvignon produced in Chile and their relationship to commercial value

The phenolic composition of wine depends on, among other factors, the grapes used to make it. In this sense, knowledge of the chemical composition of grapes and its association with the resulting wines is an important tool to determine if there is a relationship between the phenolic composition of grapes and the price that these wines obtain in the market. For this purpose, grape skins and seeds from the cultivar Cabernet Sauvignon from the central region of Chile, in 2009 and 2010 vintages from two ripening points, were subjected to chemical and phenolic analyses, as were the wines made from these grapes. Grapes and the corresponding wines from three retail price wine categories, U.S. $6-8, U.S. $28-30, and U.S. $150-160, were evaluated. No differences were found across the price categories in the chemical analysis of grapes. Berry skins and wines from the higher price categories presented a higher concentration only of total tannins, and the differences in their concentrations were only among the different fractions of proanthocyanidins in the skins, seeds, and wines; there were no differences in their proportions. A seasonal effect influenced the concentrations of certain compounds in grapes and led to a decrease in the concentration of total phenols, total tannins, and total anthocyanins between sampling dates as harvesting moved toward the common commercial grape harvest in Chilean viticulture.

Arginine 66 residue of Fur is required for the regulatory function of this protein in the acid adaptation mechanism of Helicobacter pylori

BACKGROUND

Helicobacter pylori colonizes the gastric mucosa and must survive the acid pH of that environment. Like other enteric bacterial pathogens, including Salmonella enterica, H. pylori develops an acid tolerance response that is dependent on the function of the transcriptional regulator protein Fur.

OBJECTIVE

To explore by site-directed mutagenesis whether two particular amino acid residues in the amino acid sequence of the H. pylori Fur protein, arginine 66 and histidine 99, are involved in the acid response mechanism in this bacterium.

MATERIALS AND METHODS

Complementation assays in Escherichia coli H1780 (fur null mutant) both with plasmids carrying the H. pylori fur gene bearing substitution mutations R66A or H99A or R66A/H99A and with the H. pylori Fur-R66A mutant were conducted. Wild-type and mutated Fur proteins from H. pylori were assayed by using the fiu::lacZ reporter gene in the E. coli H1780 heterologous system at various pH and iron concentrations.

RESULTS

Both bacterial growth and repression of the reporter gene were impaired under acid conditions in E. coli H1780 complemented with pUC19-fur-R66A. Also, in the H. pylori Fur-R66 strain bacterial growth and speA gene expression were impaired under acid conditions.

CONCLUSIONS

Arginine 66 but not histidine 99 in H. pylori Fur is required for the regulatory function of the Fur protein in the acid adaptation mechanism of the bacterium.

tlpA gene expression is required for arginine and bicarbonate chemotaxis in Helicobacter pylori

About half of the human population is infected with Helicobacter pylori, a bacterium causing gastritis, peptic ulcer and progression to gastric cancer. Chemotaxis and flagellar motility are required for colonization and persistence of H. pylori in the gastric mucus layer. It is not completely clear which chemical gradients are used by H. pylori to maintain its position. TlpA, a chemotaxis receptor for arginine/ bicarbonate, has been identified. This study aimed to find out whether tlpA gene expression is required for the chemotactic response to arginine/bicarbonate. Wild-type motile H. pylori ATCC 700392 and H. pylori ATCC 43504, a strain having an interrupted tlpA gene, were used. Also, a tlpA-knockout mutant of H. pylori 700392 (H. pylori 700-tlpA::cat) was produced by homologous recombination. Expression of tlpA was assessed by a Reverse Transcriptase-Polymerase Chain Reaction (RT-PCR) assay. Chemotaxis was measured as a Relative Chemotaxis Response (RCR) by a modified capillary assay. H. pylori 700392 presented chemotaxis to arginine and sodium bicarbonate. H. pylori 700-tlpA::cat showed neither tlpA gene expression nor chemotaxis towards arginine and bicarbonate. Besides confirming that TlpA is a chemotactic receptor for arginine/bicarbonate in H. pylori, this study showed that tlpA gene expression is required for arginine/bicarbonate chemotaxis.

Quantitative determination of interactions between tannic acid and a model protein using diffusion and precipitation assays on cellulose membranes

Astringency perception has been associated with interactions between tannins present in some foods and salivary proteins. A variety of laboratory methods to measure tannin-protein interactions have been designed. Most of them, however, do not differentiate clearly between tannins and the protein fraction. The aim of this work was to characterize a method to measure tannin-protein interactions by following the behavior of the protein fraction. Experiments were performed with a representative hydrophilic globular protein, bovine serum albumin (BSA), and a gallotannin-rich commercial product, tannic acid (TA). Using cellulose membranes, concentration dependency of the inhibitory effect of TA upon the diffusion of BSA on the membrane and the ability of TA to precipitate BSA were assayed. Selective staining of the protein fraction was obtained using Coomassie Blue. TA inhibited BSA diffusion in a concentration-dependent manner in the range from a 0.1-0.2 up to a 1 microg of TA/microg of BSA ratio. Likewise, maximal precipitation of BSA (equivalence point) occurred at a 0.55 microg of TA/microg of BSA ratio, that is, when about 36 representative molecules of TA (average molecular weight = 1000) interact with every molecule of BSA (molecular weight = 66, 000). The procedure may be readily adapted to measure interactions between different types of tannins and proteins that may be of relevance for taking decisions during food manufacturing.

Comparative study of the phenolic composition of seeds and skins from Carménère and Cabernet Sauvignon grape varieties (Vitis vinifera L.) during ripening

The phenolic composition of skins and seeds from Vitis vinifera L. cv. Carménère and Cabernet Sauvignon grapes during ripening was evaluated by high-performance liquid chromatography-diode array detection and spectrophotometric analysis. As compared to Cabernet Sauvignon grape skins, Carménère grape skins presented higher contents of total anthocyanins, monomeric flavan-3-ols, and total flavonoids, a higher mean degree of polymerization, a higher percentage of galloylation, a higher average molecular weight of the flavanol fraction, and a higher color intensity. As compared to Cabernet Sauvignon grape seeds, Carménère grape seeds presented a lower content of monomeric flavan-3-ols, a higher mean degree of polymerization, a higher percentage of galloylation, a higher average molecular weight of the flavanol fraction, a lower content of (+)-catechin, and higher contents of (-)-epicatechin, epicatechin-3-O-gallate, gallic acid, and dimeric procyanidins esterified with gallic acid. Altogether, we conclude that Carménère grapes present a differential composition and evolution of phenolic compounds when compared to Cabernet Sauvignon grapes.

Enhancement of both salivary protein-enological tannin interactions and astringency perception by ethanol

Red wine astringency has been associated with interactions of tannins with salivary proteins. Tannins are active protein precipitants. Not much evidence exists demonstrating contribution of other wine components to astringency. We aimed to investigate an eventual role of ethanol both in astringency and salivary protein-enological tannin interactions. A trained sensory panel scored perceived astringency. Salivary protein-tannin interactions were assessed by observing both tannin-dependent changes in salivary protein diffusion on cellulose membranes and tannin-induced salivary protein precipitation. Proanthocyanidins and gallotannins in aqueous and hydroalcoholic solutions were assayed. A biphasic mode of diffusion on cellulose membranes displayed by salivary proteins was unaffected after dilution with water or enological concentrations of ethanol. At those concentrations ethanol was not astringent. In aqueous solution, tannins provoked both restriction of salivary protein diffusion, protein precipitation, and astringency. Those effects were exacerbated by 13% ethanol. In summary, enological concentrations of ethanol exacerbate astringency and salivary protein-tannin interactions.

Chromosomal size conservation through the cell cycle supports karyotype stability inTrypanosoma cruzi

The Trypanosoma cruzi karyotype shows an extensive chromosomal size polymorphism. Absence of condensed mitotic chromosomes and chromatin fragility are characteristic features of T. cruzi which would allow DNA breaks and chromosomal rearrangements during cell proliferation. We have investigated by pulsed field gel electrophoresis (PFGE) eventual changes in chromosomal size during exponential and stationary phases of T. cruzi epimastigotes in culture, in G0 trypomastigotes and throughout the cell cycle in synchronized epimastigotes. T. cruzi molecular karyotype was stable throughout the cell cycle and during differentiation. Thus, the chromosomal size polymorphism previously reported in T. cruzi contrasts with the stability of the molecular karyotype observed here and suggests that chromosomal rearrangements leading to changes in chromosomal size are scarce events during the clonal propagation of this parasite.

Patterns and variability in electrophoretic polypeptide profiles of human saliva in a healthy population

Electrophoretic polypeptide profiles of normal human saliva differ markedly between different reports. Since both methodological variations and polymorphism may explain these differences, in this study we aimed to establish whether or not the salivary electrophoretic polypeptide profiles of subjects from a healthy population share discrete molecular features. To this end, parotid, submandibular/sublingual and whole salivas were collected separately from each of 40 young and 34 elderly clinically healthy adults and processed for SDS-polyacrylamide gel electrophoresis and Coomassie blue staining. Each type of glandular saliva displayed a different group of invariant (i.e. present in every subject) electrophoretic polypeptide bands while whole saliva showed a profile that reflected mostly the combined contribution of the major salivary glands. Some minor variant (i.e. absent in some subjects) bands were identified in each type of saliva. Regarding those interindividual variations, no age- or sex-dependence was appreciated. Altogether, these results demonstrate the occurrence of distinctive electrophoretic polypeptide patterns, in addition to some minor variations, for each type of normal saliva, thus providing a background for further populational studies on salivary polypeptide profiles.