The effect of glycosylation on the interfacial properties of bovine caseinomacropeptide

The two major fractions of bovine caseinomacropeptide (CMP), the glycosylated gCMP and non-glycosylated aCMP, were studied for their emulsifying properties. The main finding was that aCMP showed significantly better emulsifying properties than gCMP. While aCMP showed an emulsifying activity index (EAI) of 150.7 g/m², gCMP achieved a value of 98.5 g/m². Stability of emulsions was 1.4 times higher for aCMP as compared to gCMP. Droplet size measurements and creaming studies showed a strong influence of pH on both fractions with minimal emulsion stabilities at pH 4.1 (gCMP) and 4.9 (aCMP). Investigation of the flocculation behaviour and variations of the ionic strength indicate that the glycan side chains induce a combination of electric, steric and hydrophilic effects, preventing an ordered adsorption of gCMP molecules at the oil/water interface, while aCMP builds a stable network at the surface. For further elucidation, zeta potential measurements for both fractions were performed, resulting in isoelectric points of 3.15 for gCMP and 4.15 for aCMP in bulk solution. Finally, a hypothesis of surface adsorption of CMP is presented as a function of glycosylation and pH based on experimental data supported by an approach using protein modelling techniques.     

The short-chain fatty acids as potential protective agents against Callosobruchus maculatus infestation

The cowpea weevil, Callosobruchus maculatus, is one of the most common pests of stored legumes. Its occurrence adversely affects the quality of stored beans, making them unfit for consumption, resulting in substantial financial losses. The aim of this study was to investigate the potential insecticidal properties of the volatile fatty acids (VFAs) (C1 – C5) and their influence on the insect’s physiology and behavior. All VFAs in concentrations equal to 4  μl and 8  μl showed fumigant toxicity significantly higher from the control. The strongest effect was observed in the case of propionic and valeric acid in volume of 4  μl and 8  μl, where mortality was close to 100%. Except for butyric acid, all acids showed a significant repellent effect. Additionally, all VFAs significantly decreased the number of infested beans and influenced the locomotor activity. Of all tested acids only the formic acid did not affect the oxygen consumption of the insects. As the studied VFAs have noteworthy properties against C. maculatus, they could be considered as promising agents in new strategies for stored products pest management.     

Tyrosol exerts a protective effect against dopaminergic neuronal cell death in in vitro model of Parkinson’s disease

Experimental evidence suggests that tyrosol [2-(4-hydroxyphenyl)ethanol] exhibits potent protective activities against several pathogeneses. In this study, we evaluated the protective effect of tyrosol against 1-methyl-4-phenylpyridinium (MPP⁺)-induced CATH.a neuron cell death. Tyrosol dose-dependently protected CATH.a cells from MPP⁺-induced cell death and the protection was more apparent after prolong incubation (48 h). The data showed that tyrosol treatment suppressed the reduction of phospho-tyrosine hydroxylase level in CATH.a cells. Further, the compound repressed MPP⁺-induced depletion of mitochondrial membrane potential (Δψ_m) and thereby maintained intracellular ATP production in the cell. The cellular signalling pathway studies revealed that tyrosol protected CATH.a cells from MPP⁺-induced apoptotic signalling, most likely via activation of PI3K/Akt signalling pathway along with up-regulation of anti-oxidative enzymes (SOD-1 and SOD-2) and DJ-1 protein in the cell. Collectively, present study demonstrates that tyrosol significantly protects dopaminergic neurons from MPP⁺-induced degradation, and reveals potential neuroprotective mechanism of tyrosol.     

The protective effect of 23 paint systems on wood against attack by decay fungi

A laboratory method was used to evaluate the protective effect of 23 different paint systems on Norway spruce wood against decay fungi. Weather-o-meter treated and non-treated paint films on wood were tested. Results were compared to those obtained on unprotected spruce wood. Finishes included in the study were primer oils, solvent-borne alkyd paints, water-borne acrylic paints, water-borne mixed alkyd/acrylic paints, alkyd emulsions and stains in different paint system combinations with one to four coats. The growth of the decay fungi of the paint films was estimated by visual inspection. After 5 months of incubation, microbial activity in the wood below the paint films was evaluated. Growth of the fungi in the wood below the paint film was measured by an indirect chemical method for estimation of microbial activity. Paint systems including a solvent-borne alkyd coat usually had a good performance when tested without prior weathering but degenerated most during the weathering process as judged from the altered water absorption and fungal growth rate. Paint systems including a treatment with a primer oil exhibited low moisture uptake also after weathering. A clear effect of fungicide additions was also seen. A water-borne penetrating oil with an acrylic top coat exhibited no visual surface attack before weathering, and low microbial activity in wood for all decay fungi before and after weathering.     

天然虾青素对辐射损伤小鼠辅助保护作用

目的:探讨天然虾青素对小鼠辐射损伤的保护作用。方法:将144只小鼠随机分为3个实验组,剂量分别为100、200、600mg/kg·bw,另设一个辐射对照组,每天灌胃1次,连续20d后,各组均以60Co射线进行一次全身照射,并继续给样品。辐照前、辐照后第3d和14d进行外周血细胞计数;辐照后第3d进行骨髓有核细胞计数和骨髓细胞微核实验;辐照后第14d测定血清溶血素。结果:与辐照模型对照组比较,600mg/kg·bw剂量组能增加外周血白细胞计数,增加小鼠血清溶血素含量,200mg/kg·bw和600mg/kg·bw剂量组能增加小鼠骨髓有核细胞数,降低骨髓细胞微核率。结论:天然虾青素对辐射损伤具有一定的保护作用。     

Monitoring the effect of three humic acids on a model membrane system using 31P NMR

The sorption of three humic acids to 1,2-dipalmitoyl-sn-glycero-3-phosphocholine multilamellar vesicle model membrane systems was studied by phosphorus nuclear magnetic resonance (31P NMR). The effects of temperature and pH were investigated. The gel --> bilayer transition did not appear to be affected by any of the humic acids at pH 7; however, all three humic acids induced a perturbation to this transition and to the bilayer structure at pH 4. On the basis of the findings from this and other work, a conceptual adsorption/absorption model for the sorption of humic acid (HA) to biomembranes has been put forward. The model requires an initial adsorption step initiated at an acidic pH by hydrogen bridging and electrostatic interactions between the functional groups of the HAs and the head groups of the phospholipids. Once the HA material is adsorbed, its hydrophobic domains can further seek a more thermodynamically favorable environment within the bilayer using hydrophobic interactions. These interactions lead to the HA being absorbed into the membrane, which subsequently induces the observed perturbation by disturbing the ordered packing of the phospholipid tail groups. This model is also related to other humic substances/biomembrane observations in the literature.     

Antioxidant activity of sugar molasses, including protective effect against DNA oxidative damage

ABSTRACT:  Extracts were obtained from molasses, a byproduct of the sugar industry, via a number of chromatographic steps. Their antioxidant capacity was studied, including the inhibitory effect upon DNA oxidative damage; the phenolic compound profile thereof was ascertained as well. Two extracts exhibited significant antioxidant features, expressed by their capacity to decolorize ABTS radical cation and to scavenge hydroxyl free radicals (via deoxyribose assay). Those 2 extracts also brought about protection against induced DNA oxidative damage (via decreasing DNA scission, as assessed by electrophoresis). The phenolic compounds syringic acid, p -hydroxybenzoic acid, vanillic acid, p -hydroxybenzaldehyde, and ferulic acid were positively identified and quantified.     

糖类物质对固定化脂肪酶的保护作用

探讨脂肪酶在固定化过程中,几种糖类物质对酶活的保护作用.采用壳聚糖涂层法固定化脂肪酶,加入不同种类的糖液,干燥后用橄榄油法检测脂肪酶的酶活力.在没有糖类物质作为保护剂的情况下,戊二醛浓度在7.5%、交联温度在25℃、pH值为8.0时获得的固定化酶活最高,加入0.5M浓度的糖溶液,可以有效提高固定化酶活力的回收率.糖类保护剂都可以在酶的固定化过程中有效保护酶活.     

Protective effect of resveratrol against pseudorabies virus-induced reproductive failure in a mouse model

Resveratrol (RES), a natural polyphenol that is abundant in grapes, exerts anti-inflammatory, anti-oxidative, and antiviral bioactive effects. Protective effects of RES against pseudorabies virus (PrV)- induced reproductive failure were investigated in a mice model. Injection of PrV partially induced stillbirth and abortion, and caused poor growth of progeny. Treatment with RES attenuated the reproductive failure induced by the virus with recovery of the serum progesterone level. RES improved the growth performance of newborn mice. RES can attenuate the reproductive failure induced by PrV in mice.     

The effect of sugars and pectin on flavour release from a soft drink-related model system

Three types of sugar and high-methoxyl pectin at different concentrations were added to a soft drink-related model system consisting of water and six flavour compounds. The addition of these ingredients contributes to changes in viscosity and water activity, which in turn affects the release of the flavour compounds to the gas phase above the soft drink. In the study, a higher concentration of sucrose and invert sugar increased the release of five flavour compounds, probably owing to a so-called “salting-out” effect. Starch syrup at a concentration of 60% increased the amount of three of the flavour compounds released and would probably increase the release of more compounds at a higher concentration. When pectin was added to the system, it was seen that viscosity does not influence release of the flavour molecules, but that the kind of stabiliser used is more important.     

The effect of ascorbate reductants on N-nitrosamine formation in a model system resembling bacon fat

The nitrosation of dipropylamine and pyrrolidine have been examined in two-phase systems comprising aqueous buffer and non-polar solvent. Contrary to previous observations in purely aqueous systems, sodium ascorbate increased amine nitrosation in this two-phase simulated fat system by between 5 and 25 times compared with ascorbate-free controls. Lipophilic ascorbyl palmitate, however, generally reduced nitrosation.     

The protective effect of green and black teas (Camellia sinensis) and their identified compounds against murine sepsis

Several compound classes could be identified in the infusion of green tea (GTI) and black tea (BTI) from Camellia sinensis, mainly catechins and their gallate derivatives in GTI and their oxidation products, theaflavins and theasinensins, in BTI. We also managed to identify other components, such as proanthocyanidins, flavonoid glycosides, alkaloids, hydroxybenzoic and hydroxycinnamic acids and saponins. The infusions were fractionated and the ethyl acetate fractions [green tea ethyl acetate fraction (GEAF) and black tea ethyl acetate fraction (BEAF)] have concentrated the catechins, theaflavins and caffeine. So, the infusions, fractions and major compounds identified from both teas were assayed against murine sepsis, in order to assess whether they are effectively protecting from this pathology. The infusions at 70 mg/kg resulted in a decrease of sepsis mortality in 43% (GTI) and 40% (BTI), respectively. The ethyl acetate fractions were also efficient, allowing a survival rate of 50% (GEAF) and 66.6% (BEAF) at concentrations of 30 and 70 mg/kg, respectively. The main components from GEAF and BEAF were also assayed; epigallocatechin gallate (10 mg/kg), theaflavins (9 mg/kg) and caffeine (18 mg/kg) showed a survival rate of 50%, 40% and 20%, respectively. This protective effect can be explained, at least in part, by some of these compounds' ability to modulate some important inflammatory parameters, such as neutrophil influx, avoiding its accumulation in lungs, depletion of the pro-inflammatory cytokines (TNF-α and IL-6), increase the anti-inflammatory cytokine (IL-10) and, also, a significant decrease in tissue expression of iNOS and COX-2.     

The effect of pH on the formation of maillard-derived aroma volatiles using a cooked meat system

The effect of pH on the formation of volatile compounds was investigated using minced beef in which the pH was adjusted within the range 4.0–5.6, by the addition of hydrochloric acid before cooking. The strong buffering capacity of the meat ensured that the pH did not vary during heating. Volatiles were analysed using headspace concentration and gas chromatography-mass spectrometry. The total quantity of volatile compounds increased as the pH decreased. A number of furanthiols and their oxidation products were preferentially formed at acid pH; some of these compounds had strong meaty aromas. The formation of other heterocyclic compounds such as thiazoles and pyrazines were favoured by higher pH.     

The minipig as a model in gnotobiology

Due to its close physiological and morphological resemblance to man, the pig occupies an important position in biomedical research. The minipig lends itself particularly well to germfree research. It is easy to deliver, maintain, and utilize in isolators. The colostrum-free, newborn germfree piglet lacking passively obtained antibodies is of an exclusive use if distinguishing the factors of natural and adaptive immunity is needed. It fits also well in studies investigating the earliest mechanisms of antibody synthesis. Under germfree conditions, the pig has been proved an excellent model for testing the action of ionizing radiation as well as of selected bacterial strains when monoassociated. Recently, conventional pigs have been used also for studies in total or selective decontamination of the intestinal tract by antibiotics and strict isolation.     

High-ratio yellow cake. The starch cake as a model system for response to chlorine

Starch was extracted from wheat by wet milling, purified by differential centrifugation in water and substituted for flour in a high-ratio yellow cake recipe. Carboxymethyl cellulose (1 % of the starch weight) was included to compensate for the poor water absorbing capacity of the starch. The cakes, in contrast to those prepared with flour (unchlorinated), did not suffer structural collapse on cooling. Further purification of the starch, accomplished by repeated shaking with toluene and water and removal of the emulsions so formed, led to cakes which did collapse. The collapse was prevented by chlorination of the toluenetreated starch and this system thus provides a potentially useful model for simulating the response of wheat flour to chlorine.