Granulomatous lesions in lymph nodes of slaughter pigs bacteriologically negative for Mycobacterium avium subsp. avium and positive for Rhodococcus equi     

Komijn RE  Wisselink HJ  Rijsman VM  Stockhofe-Zurwieden N  Bakker D  van Zijderveld FG  Eger T  Wagenaar JA  Putirulan FF  Urlings BA 《Veterinary microbiology》2007,120(3-4):352-357

The prevalence of granulomatous lesions in lymph nodes of pigs was studied. From January till August 2004 in two slaughterhouses in The Netherlands 2,116,536 pigs were examined for the presence of granulomatous lesions in the sub-maxillary lymph nodes. In 15,900 (0.75%) of these pigs, lesions could be detected. Nine farms with the highest incidence of lesions were selected for a more detailed pathological and bacteriological examination. On these farms, the prevalence of lesions in sub-maxillary lymph nodes ranged from 2.3 to 5.7% with a mean of 3.0%. From 1276 pigs that were sampled, 98 (7.7%) displayed granulomatous lesions in the sub-maxillary lymph nodes and one (0.1%) pig showed lesions in its mesenteric lymph node. Mycobacterium avium subsp. avium (MAA) could not be isolated from the lymph nodes of the 99 pigs with lesions and from a selection of lymph nodes (n = 61) of pigs without lesions. Rhodococcus equi was isolated from 44 out of 98 (44.9%) of the sub-maxillary lymph nodes with granulomatous lesions and from two mesenteric lymph nodes without lesions. A comparison of former studies and the current results indicate that the prevalence of MAA infections in slaughter pigs has strongly decreased over the last decade, whereas R. equi is highly prevalent. The high incidence of granulomatous lesions associated with the bacteriological presence of R. equi could be considered as a serious cause of misdiagnosis of MAA infections in cases where meat inspection is carried out by inspection for granulomatous changes of lymph nodes only.  相似文献   

In vitro fermentability of differently substituted xylo-oligosaccharides     

Kabel MA  Kortenoeven L  Schols HA  Voragen AG 《Journal of agricultural and food chemistry》2002,50(21):6205-6210

Xylo-oligosaccharides (XOS) with various substituents were fermented in vitro by fecal inocula (FI) from four human volunteers to study the influence of substitution on the ability and rate of fermentation and on the production of short-chain fatty acids (SCFA) and lactate. By all FI used nonsubstituted XOS (nXOS) and arabino-XOS (AXOS) were fermented more quickly than the more complex structures of acetylated XOS (AcXOS) and XOS containing a 4-O-methylglucuronic acid group (GlcA(me)XOS). In the first stage (0-40 h) of the fermentations of nXOS and AXOS mainly acetate and lactate were formed. The fermentations of AcXOS and GlcA(me)XOS resulted in a lower lactate production, whereas the concentration of propionate and butyrate increased. These results put emphasis on the detailed elucidation of the structural features of nondigestible oligosaccharides in general to understand their fermentation mechanisms more precisely.  相似文献   

Low molecular weight melanoidins in coffee brew   总被引：1，自引：0，他引：1  

Bekedam EK  Roos E  Schols HA  Van Boekel MA  Smit G 《Journal of agricultural and food chemistry》2008,56(11):4060-4067

Analysis of low molecular weight (LMw) coffee brew melanoidins is challenging due to the presence of many non-melanoidin components that complicate analysis. This study focused on the isolation of LMw coffee brew melanoidins by separation of melanoidins from non-melanoidin components that are present in LMw coffee brew material. LMw coffee fractions differing in polarity were obtained by reversed-phase solid phase extraction and their melanoidin, sugar, nitrogen, caffeine, trigonelline, 5-caffeoylquinic acid, quinic acid, caffeic acid, and phenolic groups contents were determined. The sugar composition, the charge properties, and the absorbance at various wavelengths were investigated as well. The majority of the LMw melanoidins were found to have an apolar character, whereas most non-melanoidins have a polar character. The three isolated melanoidin-rich fractions represented 56% of the LMw coffee melanoidins and were free from non-melanoidin components. Spectroscopic analysis revealed that the melanoidins isolated showed similar features as high molecular weight coffee melanoidins. All three melanoidin fractions contained approximately 3% nitrogen, indicating the presence of incorporated amino acids or proteins. Surprisingly, glucose was the main sugar present in these melanoidins, and it was reasoned that sucrose is the most likely source for this glucose within the melanoidin structure. It was also found that LMw melanoidins exposed a negative charge, and this negative charge was inversely proportional to the apolar character of the melanoidins. Phenolic group levels as high as 47% were found, which could be explained by the incorporation of chlorogenic acids in these melanoidins.  相似文献   

Electron spin resonance (ESR) studies on the formation of roasting-induced antioxidative structures in coffee brews at different degrees of roast     

Bekedam EK  Schols HA  Cämmerer B  Kroh LW  van Boekel MA  Smit G 《Journal of agricultural and food chemistry》2008,56(12):4597-4604

The antioxidative properties of coffee brew fractions were studied using electron spin resonance spectroscopy using 2,2,6,6-tetramethyl-1-piperidin-1-oxyl (TEMPO) and Fremy's salt (nitrosodisulfonate) as stabilized radicals. TEMPO was scavenged by antioxidants formed during roasting and not by chlorogenic acid, whereas Fremy's salt was scavenged by all antioxidants tested including chlorogenic acid. The stabilized radical TEMPO allowed the exclusive measurement of roasting-induced antioxidants. The roasting-induced antioxidant activity of coffee brews increased with increasing degree of roast, and most of these antioxidants were formed during the initial roasting stage. The majority of these roasting-induced antioxidants were present in the high molecular weight fractions, indicating that the formation of these antioxidants preferably occurs at specific high molecular weight structures, likely being arabinogalactan and/or protein moieties which might be part of the melanoidin complex. It was found that chlorogenic acids most probably do not lose their antioxidant activity and phenolic characteristics upon incorporation in coffee melanoidins. The parameter fast reacting antioxidants (FRA) was introduced as an alternative for the antioxidative potential. FRA levels showed that coffee fractions rich in roasting-induced antioxidants exposed their antioxidant activity relatively slowly, which must be a consequence of its complex structure. Finally, the melanoidin content and the roasting-induced antioxidant activity showed a positive and linear correlation for the coffee brew fractions, showing that roasting-induced antioxidants are present within melanoidins. This is the first time that the formation of roasting-induced antioxidants could be directly correlated with the extent of Maillard reaction and melanoidin formation in a complex product such as coffee.  相似文献   

High molecular weight melanoidins from coffee brew     

Bekedam EK  Schols HA  van Boekel MA  Smit G 《Journal of agricultural and food chemistry》2006,54(20):7658-7666

The composition of high molecular weight (HMw) coffee melanoidin populations, obtained after ethanol precipitation, was studied. The specific extinction coefficient (K(mix)) at 280, 325, 405 nm, sugar composition, phenolic group content, nitrogen content, amino acid composition, and non-protein nitrogen (NPN) content were investigated. Results show that most HMw coffee melanoidins are soluble at high ethanol concentrations. The amino acid composition of the HMw fractions was similar, while 17% (w/w) of the nitrogen was NPN, probably originating from degraded amino acids/proteins and now part of melanoidins. A strong correlation between the melanoidin content, the NPN, and protein content was found. It was concluded that proteins are incorporated into the melanoidins and that the degree of chemical modification, for example, by phenolic groups, determines the solubility of melanoidins in ethanol. Although the existence of covalent interaction between melanoidins and polysaccharides were not proven in this study, the findings suggest that especially arabinogalactan is likely involved in melanoidin formation. Finally, phenolic groups were present in the HMw fraction of coffee, and a correlation was found with the melanoidin concentration.  相似文献   

Middle Paleolithic shell beads in Israel and Algeria     

Vanhaereny M  d'Errico F  Stringer C  James SL  Todd JA  Mienis HK 《Science (New York, N.Y.)》2006,312(5781):1785-1788

Perforated marine gastropod shells at the western Asian site of Skhul and the North African site of Oued Djebbana indicate the early use of beads by modern humans in these regions. The remoteness of these sites from the seashore and a comparison of the shells to natural shell assemblages indicate deliberate selection and transport by humans for symbolic use. Elemental and chemical analyses of sediment matrix adhered to one Nassarius gibbosulus from Skhul indicate that the shell bead comes from a layer containing 10 human fossils and dating to 100,000 to 135,000 years ago, about 25,000 years earlier than previous evidence for personal decoration by modern humans in South Africa.  相似文献   

非均匀土壤区域SVAT模型中土壤水动力学参数的整合研究     

袁锋明  赖世龙  Wies Vulllings  Henk Wosten 《植物营养与肥料学报》2000,6(3):323

荷兰Cabauw地区一个 10km×10km区域内的四种主要土壤的水动力学参数用一种实验室直接测定法 (Wind氏蒸发法 )和两种间接方法 (“分段土壤推导函数”、“连续土壤推导函数”)确定 ,而该区域水动力学特性参数的整合则采用两组方案 (聚合土壤参数法和有效土壤参数法 )进行。一个SVAT模型的模拟输出结果———感热通量、潜热通量与实测数据的比较分析表明 :(1)对于用“分段土壤推导函数”确定的土壤水动力学参数的区域整合 ,以“逆模拟法”(有效土壤参数法 )较为可行 ,其模拟感热、潜热的精确性接近参比方案 (“模拟 平均法”) ;(2 )对于实验室直接测定的参数 ,则以几何平均vanGenuchten Mualem经验公式参数的方案 (聚合土壤参数法 )为佳 ;(3)对于“连续土壤推导函数”推导的水动力学参数 ,几何平均土壤组分方案 (聚合土壤参数法 )和“逆模拟法”方案 (有效土壤参数法 )二者均可得到优于参比方案 (“模拟 平均法”)的模拟结果 ,其中以前者最佳 ;(4 )所有区域化参数整合方案中 ,以水平几何平均区域内实验室直接测定的参数的方案最优 ;同时 ,“连续土壤推导函数”法的土壤组分几何平均方案的模型输出精确性接近该最优方案  相似文献