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PubMed1974

Dextrans.

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Antigen-Antibody Reactions↗
PubMed2002

Simultaneous quartz crystal microbalance impedance and electrochemical impedance measurements. Investigation into the degradation of thin polymer films.

The reproducible degradation of thin polymer films in the presence of an analyte or a reaction product of an analyte has potential applications in the development of highly sensitive, disposable biosensors. In this study, a novel combination of quartz crystal microbalance (QCM) and electrochemical impedance spectroscopy (EIS) has been developed to monitor the degradation of thin polymer films. Unlike a conventional QCM, the instrument described here allows rapid in situ measurement of quartz crystal impedance spectra. Simultaneously, classical electrochemical impedance spectra are measured in situ, affording the polymer film capacitance and bulk resistance. The combination of QCM impedance and classical EIS provides a wealth of information about the process of degradation of thin polymer films such as mass variation, swelling, delamination, viscoelasticity, and pore formation. Three different systems have been analyzed with this experimental setup; in two of the systems, polymer degradation was promoted by hydrolytic enzymes, and in the third one by a pH change. The results obtained show that the degradation of these three systems follows very different mechanisms. It is also underlined how the complementary information obtained by the two techniques allows a detailed description of the dissolution process.

Biosensing Techniques↗
PubMed1999

Mushrooms, tumors, and immunity.

Medicinal properties have been attributed to mushrooms for thousands of years. Mushroom extracts are widely sold as nutritional supplements and touted as beneficial for health. Yet, there has not been a critical review attempting to integrate their nutraceutical potential with basic science. Relatively few studies are available on the biologic effects of mushroom consumption, and those have been performed exclusively in murine models. In this paper, we review existing data on the mechanism of whole mushrooms and isolated mushroom compounds, in particular (1-->3)-beta-D-glucans, and the means by which they modulate the immune system and potentially exert tumor-inhibitory effects. We believe that the antitumor mechanisms of several species of whole mushrooms as well as of polysaccharides isolated from Lentinus edodes, Schizophyllum commune, Grifola frondosa, and Sclerotinia sclerotiorum are mediated largely by T cells and macrophages. Despite the structural and functional similarities of these glucans, they differ in their effectiveness against specific tumors and in their ability to elicit various cellular responses, particularly cytokine expression and production. Unfortunately, our data base on the involvement of these important mediators is still rather limited, as are studies concerning the molecular mechanisms of the interactions of glucans with their target cells. As long as it remains unclear what receptors are involved in, and what downstream events are triggered by, the binding of these glucans to their target cells, it will be difficult to make further progress in understanding not only their antitumor mechanisms but also their other biological activities.

Adjuvants, Immunologic↗
PubMed2004

Ethylene-induced gene expression, enzyme activities, and water soaking in immature and ripe watermelon (Citrullus lanatus) fruit.

Watermelon fruit exhibit acute softening and placental-tissue water soaking following short exposure to exogenous ethylene. Experiments were performed to address transcript abundance and activities of cell wall and membrane hydrolases in placental tissue in response to treatment of watermelon fruit with ethylene. Watermelon fruit were harvested at immature and full-ripe stages and exposed to 50 microL L(-1) ethylene for 6 days at 20 degrees C. Ethylene affected the abundance of transcripts for PME (EC 3.2.1.11), and alpha-(EC 3.2.1.22) and beta-GAL (EC 3.2.1.23) but these effects were dependent on fruit maturity and appeared not to be associated with the water-soaking syndrome. PG (EC 3.2.1.15) and EXP mRNAs accumulated significantly in response to ethylene exposure. Additionally, the levels of mRNA and activities of LOX (EC 1.13.11.12), PLC (EC 3.1.4.3) and PLD (EC 3.1.4.4) were elevated in fruit of both maturity classes exposed to ethylene and were temporally associated with the visible symptoms of water soaking. The activity trends and transcript abundance in ethylene- compared with air-treated fruit indicate that PG, EXP, LOX, PLC and PLD levels increase with the onset and development of the water-soaking disorder and support the view that catabolic reactions targeting the membranes and cell-walls contribute to the disorder.

Cell Wall↗
PubMed2003

Effect of enzyme preparation containing xylanase and beta-glucanase on performance of laying hens fed wheat/barley- or maize/soybean meal-based diets.

1. A commercial enzyme preparation (Quatrazyme HP) containing xylanase and beta-glucanase was examined in two laying hen experiments with wheat/barley- or maize-based diets. The activities of other enzymes were measured also. Starch, cell wall contents and effects of Quatrazyme HP on in vitro viscosity of wheat, barley, maize and soybean meal were determined. 2. In the first experiment, 90 ISA Brown laying hens at 28 weeks of age were given a wheat/barley basal diet with or without 20mg of Quatrazyme HP, which provided 560 and 2,800 IU of xylanase and beta-glucanase/kg diet. In the second experiment, 66 ISA Brown laying hens at 45 weeks of age were given a maize/soybean meal basal diet with or without 20 mg of Quatrazyme HP/kg diet for 9 weeks. Egg production, egg weight, egg mass, feed conversion ratio and change in body weight were recorded as response criteria. 3. There was a significant improvement in feed conversion ratio with enzyme supplementation. Birds given an enzyme-supplemented diet gained 86 g while those fed on the unsupplemented diet lost 103 g of their body weight by the end of the experiment. 4. The enzyme preparation did not affect either egg production, egg weight or egg mass of birds fed on the maize/soybean meal diet. However, a significant improvement in feed conversion ratio was detected. Birds on either the supplemented or unsupplemented diet exhibited an increase in their body weight at the end of the experiment. 5. Addition of xylanase and beta-glucanase decreased in vitro viscosity of wheat, barley, maize and soybean meal. This effect was greater for wheat and barley than for maize and soybean meal. 6. It was concluded that the beneficial effect of using an enzyme preparation containing xylanase and beta-glucanase is not limited to wheat/barley-based diets but also occurs with maize/soybean meal-based diets.

Animal Feed↗
PubMed2003

The effect of chaya (Cnidoscolus aconitifolius) leaf meal and of exogenous enzymes on amino acid digestibility in broilers.

1. The apparent ileal nitrogen (N) and amino acid digestibilities in chaya leaf meal (CLM) (Cnidoscolus aconitifolius) with added enzymes, and the same variables in diets containing different amounts of CLM were studied in chickens. 2. In the first experiment pectinase, beta-glucanase, and pectinase + beta-glucanase were added to CLM. In the second experiment, there were three diets based on maize and soybean: 0, 150 and 250 g/kg CLM. 3. Pectinase significantly increased both lysine and overall amino acid digestibilities in CLM. 4. In experiment 2, the amino acid digestibility in birds fed on CLM250 was lower than that from birds fed on either control or CLM150. Only the digestibilities of alanine, arginine and proline were lower in birds fed on CLM150 than in those fed on the control diet. Nitrogen digestibility was lower in birds fed on the CLM250 diet than on either control or CLM150 diets. These findings were attributed to the increasing concentration of fibre with increasing dietary CLM.

Amino Acids↗
PubMed2005

Characterization of two Candida albicans surface mannoprotein adhesins that bind immobilized saliva components.

Salivary components, including the basic proline-rich proteins (bPRP), act as receptors for the adherence of Candida albicans, and this interaction may be important for oral colonization and the development of mucosal Candida infections. Treatment of C. albicans cells with agents affecting either proteinacious or carbohydrate surface macromolecules reduced their adherence in in vitro assays of C. albicans adherence to saliva-coated hydroxyapatite beads and to membrane-immobilized salivary bPRP. In order to identify C. albicans adhesins that bind saliva receptors, yeast cell surface material was extracted by mild glucanase treatment, and was shown to competitively inhibit ( > 50%) the adherence of C. albicans yeast cells in both assays. Concanavalin A sepharose affinity chromatography was used to partially purify glycosylated components of the extract, and two polypeptides (97.4 and 35 kDa) were further purified by preparative SDS PAGE separation and electro-elution. The 97.4 and 35 kDa polypetides each possessed greater adherence-inhibitory specific activity (> 100-fold and > 30-fold respectively) than the original glucanase extract from C. albicans yeast cells. The 35 kDa putative surface protein was identified by N-terminal sequencing and immunoblotting, as the 1,3-beta glucosyltransferase, Bgl2p.

Amino Acid Sequence↗
PubMed1992

Multiplex random priming of internal restriction fragments for DNA sequencing.

An approach for DNA sequencing is described that circumvents the need for synthetic oligonucleotide primers, which seriously restrict the progress of DNA sequencing in the commonly used protocol. The method is based on the use of short restriction fragments as primers randomly distributed along single-stranded templates. Premapping of target DNA is eliminated and subcloning manipulation is minimized. This method has been used successfully for sequencing genes in the range of 2 kb, for which about 10 restriction fragment primers per kilobase were sufficient to generate a continuous overlapping sequence in alignment. The approach has also been readily applied for an automated sequencing system with the fluorescent chain-terminating dideoxynucleotides, thus implying its potential for sequencing large genomic DNAs.

Automation↗