口腔癌患者唾液中一种标记物的高效液相色谱荧光检测法及诊断价值研究

本文利用高效液相色谱荧光检测技术研究了口腔癌患者唾液中的肿瘤标记物,在所使用的色谱条件下,首次在患者唾液样品中检出一种荧光性标记物,其激发波长为442nm,发射波长为512nm。通过对24例非口腔癌患者和37例口腔癌患者唾液的HPLC-FL分析,其含量在非癌症患者中较高,而在癌症患者中却很低甚至未检出。通过采用非参数检验（Mann-Whitney U检验）,该物质含量在非癌症患者中与癌症患者中存在显著性差异（P<0.01）。数据分析表明,其特异性为94.6%,敏感度为95.8%,ROC曲线下面积为0.980,该模型具有很高的诊断价值,能够用于口腔癌的辅助诊断。     

An EPR study of free radical generation during maceration of uncooked vegetables

Electron paramagnetic resonance (EPR) spectroscopy has been used to study free radicals formed in a range of plant tissues as a result of physical damage, with the objective of gaining some insight into the free radical chemistry that is initiated when uncooked vegetable products (eg salads) are eaten. Chemical spin traps were used to aid the detection of unstable free radicals; more stable radicals were detected directly. Commonly observed ‘stable’ species were the monodehydroascorbate radical, which has a characteristic doublet spectrum, and a single‐peak resonance, which is presumed to come from free radical centres stabilised in macromolecules. In mushrooms (Agaricus spp), spin‐trapping experiments using either α‐(4‐pyridyl‐1‐oxide)‐N‐t‐butyl‐nitrone (4‐POBN) or phenyl‐t‐butyl‐nitrone (PBN) showed the formation of large quantities of adducts of the radical from 4‐hydroxymethylbenzene diazonium salts. Pleurotus species, in contrast, gave signals consistent with the formation of unidentified C‐centred radicals. With other foodstuffs, reaction with 4‐POBN was complex and signals from 4 ? POBN· and adducts were observed along with the t‐butylhydronitroxide radical (an adduct breakdown product). Investigation of carrot hypocotyl rootstock in the presence of 5‐(diethoxyphosphoryl),5‐methyl‐1‐pyrroline‐N‐oxide (DEPMPO) revealed adducts of ·OH and unidentified C‐centred radicals. Free radical interactions between food components were demonstrated by the suppression of the signal from the 4‐POBN adducts of lettuce by onion, garlic, satsuma or vinaigrette, but not by olive oil. In addition, an appreciable decrease in spectral intensity of the 4‐POBN adduct from lettuce was observed in the presence of saliva, which suggests that saliva contains free radical scavengers which are able to compete successfully with the spin trap. © 2002 Society of Chemical Industry     

The effect of flavour modulators on chewing gum flavour duration

This study investigated the impact of flavour modulators on dynamic flavour perception, salivation and chewing behaviour of chewing gum. Thirty-nine participants chewed gum for 15 min while assessing flavour intensity, chewing patterns and saliva flow rate. Four flavour modulators (Cooling, Tingling, Salivating and Warming) were added to a citrus-flavoured gum and compared with a control gum, citrus flavour only. Flavour modulators increased flavour duration as measured by flavour intensity half-time; the time needed to reduce the flavour intensity by half. The ‘Salivation’ modulator had the smallest effect and ‘Warming’ had the largest effect on flavour duration. Salivary flow rate was significantly increased by the flavour modulators and was highly correlated with the flavour duration. Chewing behaviour was not affected by the modulators. We conclude that the interaction between the citrus flavour, saliva and flavour modulators (Intensates® flavours) increased the perceived flavour duration during chewing by up to 86% compared with Control.     

Dynamic changes in salivation,salivary composition,and rumen fermentation associated with duration of high-grain feeding in cows

Salivary secretions are essential for the regulation of digestive processes, as well as rumen and cow health. This research evaluated the effects of the duration of high-grain feeding, and of the time relative to a meal, on salivation, saliva properties, feed bolus characteristics, chewing activity, ruminal and reticular volatile fatty acids, as well as salivary and ruminal pH. Nine nonlactating cannulated Holstein cows were sampled at 1 and 23 d after transition to a 65% grain diet (short term and long term, respectively). Both before and after a controlled meal (2.5 kg of dry matter, offered over 4 h), unstimulated saliva was taken orally for composition analysis. Stimulated salivation and feed boli characteristics were evaluated by collection of ingesta from cardia during 30 min. Chewing and ruminal pH were measured during the controlled meal and for a total of 6 h thereafter. Results from unstimulated saliva showed no effect of the duration of high-grain feeding on bicarbonate, phosphate, total proteins, mucins, lysozyme, and buffer capacity, but increased osmolality at the long term. Lysozyme activity did not differ with high-grain feeding duration, but tended to be lower after the meal. In contrast to short-term-fed cows, the long-term-fed cows increased both meal consumption and feed bolus size, but decreased chewing and feed ensalivation (5.2 vs. 4.6 ± 0.50 g of saliva/g of dry matter), and had lower pH of the stimulated saliva (7.00 vs. 6.67 ± 0.076). These cows also had decreased chewing index (66.5 vs. 45.4 min/kg of neutral detergent fiber), and despite the increase in stimulated saliva buffer capacity (0.027 vs. 0.039 ± 0.006), mean ruminal pH decreased (6.31 vs. 6.11 ± 0.065) during ad libitum feeding. Both in the rumen and reticulum, the concentration of total volatile fatty acids was lower and propionate proportion was higher at the long term. Linear regression analyses revealed a positive influence of the flow rates of salivary bicarbonate and phosphate on ruminal pH during the short term. For every 1-mol increment in the flow of bicarbonate or phosphate, ruminal pH increased by 0.062 or 0.439 units, respectively. Overall, salivary buffers are key determinants of ruminal pH regulation, especially during short-term grain feeding. However, in the long term, ruminal pH drop during ad libitum feeding was stronger, and this effect seems to be exacerbated by increased feed bolus size, accompanied by reductions in feed ensalivation, stimulated saliva pH, and chewing index.     

Oral enzymatic detoxification system: Insights obtained from proteome analysis to understand its potential impact on aroma metabolization

The oral cavity is an entry path into the body, enabling the intake of nutrients but also leading to the ingestion of harmful substances. Thus, saliva and oral tissues contain enzyme systems that enable the early neutralization of xenobiotics as soon as they enter the body. Based on recently published oral proteomic data from several research groups, this review identifies and compiles the primary detoxification enzymes (also known as xenobiotic-metabolizing enzymes) present in saliva and the oral epithelium. The functions and the metabolic activity of these enzymes are presented. Then, the activity of these enzymes in saliva, which is an extracellular fluid, is discussed with regard to the salivary parameters. The next part of the review presents research evidencing oral metabolization of aroma compounds and the putative involved enzymes. The last part discusses the potential role of these enzymatic reactions on the perception of aroma compounds in light of recent pieces of evidence of in vivo oral metabolization of aroma compounds affecting their release in mouth and their perception. Thus, this review highlights different enzymes appearing as relevant to explain aroma metabolism in the oral cavity. It also points out that further works are needed to unravel the effect of the oral enzymatic detoxification system on the perception of food flavor in the context of the consumption of complex food matrices, while considering the impact of food oral processing. Thus, it constitutes a basis to explore these biochemical mechanisms and their impact on flavor perception.     

Colloidal stability and interactions of milk-protein-stabilized emulsions in an artificial saliva

Oil-in-water emulsions (20 wt% soy oil) with lactoferrin or β-lactoglobulin (β-lg) as the interfacial layer were prepared using a two-stage valve homogenizer. At pH 6.8, lactoferrin produces a stable cationic emulsion whereas β-lg forms an anionic emulsion. These emulsions were mixed with an artificial saliva that contained a range of mucin concentrations and salts. Negatively charged mucin was shown to interact readily with the positively charged lactoferrin-stabilized emulsion droplets to provide a mucin coverage of approximately 1 mg/m². As expected, the negatively charged β-lg-stabilized emulsion droplets had lower mucin coverage (0.6 mg/m² surface load) under the same conditions. The β-lg-stabilized emulsions were stable but showed depletion flocculation at higher mucin levels (≥1.0 wt%). In contrast, lactoferrin-stabilized emulsion droplets showed considerable aggregation in the presence of salts but in the absence of mucin. This salt-induced aggregation was reduced in the presence of mucin, possibly because of its binding to the positively charged lactoferrin-stabilized emulsion droplets and thus a reduction in the positive charge at the lactoferrin-coated droplet surface. However, at higher mucin concentration (≥2.0 wt%), lactoferrin-stabilized emulsions also showed droplet aggregation.     

In vitro oral processing of raw tomato: Novel insights into the role of endogenous fruit enzymes

During consumption of fruits, the breakdown of the fruit tissue due to oral processing (chewing, mixing with saliva) may activate or increase the rate of endogenous enzyme activities via the disruption of the cell wall, cellular decompartmentalization, and particle size reduction allowing the enzymes to reach their substrates. The aim of this study was to investigate the activity of one such endogenous fruit enzyme (pectin methylesterase [PME] [E.C. 3.1.1.11]) during in vitro oral processing of raw tomatoes and associated changes in viscosity and microstructure. Oral processing of tomatoes purees was examined in the presence of artificial saliva (AS) at 37°C. in vitro oral processing was followed using immunofluorescence microscopy, apparent viscosity measurements, spectrophotometric, and titrimetric techniques. The results demonstrated that PME had slight but significant activity in the tomato fruit during in vitro oral processing generating methanol as a function of oral processing time, which was further evidenced using immunolabeling techniques to detect methylated pectin epitopes. A significant shear‐thinning behavior of the tomato puree was observed due to dilution and/or endogenous fruit enzyme activity. These results suggest that activity of other fruit enzymes, such as polygalacturonase, which catalyzed the depolymerization of unmethylated pectin chains, might have resulted in a decrease in viscosity, which compensated for the increased potential for gel formation (if any) caused by PME. These interesting insights into the role of endogenous fruit enzymes might pave the way to the understanding of fruit viscosity modification occurring in the mouth and help in rational design of new fruit‐based products.