Method for analysis of tannic acid and its metabolites in biological samples: application to tannic acid metabolism in the rat

A new analytical method for measuring tannic acid (TA) using tannase was developed and applied to the investigation of TA metabolism in the rat following oral administration at a dose of 1.0 g/kg. The proposed method for TA determination was based on the enzymatic hydrolysis of TA to gallic acid (GA) and subsequent determination by HPLC. TA metabolites were determined by HPLC. 4-O-Methylgallic acid (4-OMGA), pyrogallol (PY), and resorcinol (RE) were detected in serum. TA was excreted into urine as GA (0.01%), 4-OMGA (0.10%), PY (0.24%), and RE (2.06%) and into feces as TA (62.74%), GA (0.19%), PY (0.02%), and RE (0.76%) within 54 h after oral administration. It was suggested that >60% of TA remained unchanged but that some was hydrolyzed to GA by tannase in the intestine and further metabolized to 4-OMGA, PY, and RE.     

Cross-sectional cutting of bamboo with a pair of shearing blades for bamboo cube production

As a new use of bamboo, bamboo cubes may be useful as a shot-blast material for surface treatments. However, a suitable processing technique for bamboo cubes has not been established. In this study, to obtain basic knowledge regarding the processing technology for bamboo cubes, we installed shearing blades (upper and lower blades) in a universal testing machine to test cross-sectional shearing of bamboo. The shearing force generated in this shearing was composed of a vertical component (F _v), a forward component (F _f), and a side component (F _s). This shearing force (F _v, F _f, and F _s) and the machining accuracy were investigated under various processing conditions. The shearing force became larger as the thickness of bamboo increased. In particular, F _v showed a tendency to increase rapidly. Changes in the shear angle of the upper blade had a remarkable influence on F _v. This result suggests that the shearing force could be greatly decreased by adjusting the shear angle. The shearing force within bamboo of 3mm in thickness was almost unaffected by the blade angle, and the change of shearing force with increasing clearance was almost indiscernible. It was clearly demonstrated that a large number of bamboo cubes could be made when the shear angle was large and cross-sectional shearing was performed from the bark side. However, a consequence of a large shear angle is that burr area increases. Part of this article was presented at the 53rd Annual Meeting of the Japan Wood Research Society, Fukuoka, March 2003     

人类活动对中国南部荒山松林养分循环的影响

在中国南部开展对荒山马尾松(Pinus massoniana)林养分循环受人类活动影响的调查.位于江西省兴国县研究地点的一些农民从森林生态系统中收取有机物作为燃料,这引起养分循环的断裂和植被恢复的延误以及土壤侵蚀的发生.收取的量估算为相当于5.92t/hm2有机物和21.4kg/hm2氮.如果收取停止,10年之后,有机物在森林地表枯枝落叶层的积累将可恢复.     

中国南部天然常绿阔叶林的地上生物量、净初级生产力、养分分布和养分利用效率

在中国南部的江西九连山自然保护区,观测研究了天然常绿阔叶林的地上生物量、地上NPP(净初级生产力)、养分的积累和分布,以及不同生活型树种的养分利用效率.在两个样地,用相对生长回归法和收获法测定了地上生物量,数值各约为340和270t/hm2,其中叶生物量约为9.6t/hm2.地上NPP约为年9.9t/hm2,其中叶生产力占44％.各种一般养分(N,P,K,Ca,Mg,Na)在森林生态系统中积累的特点是,Na和N在矿质土壤中有高的相对分布,K和Mg属中间地位,Ca和P则高分布于地上生物量中.氮的养分利用效率(NUE)、平均停留时间(MRT)和年生产力(A)表明,针叶树是氮的最高效的利用者,常绿阔叶树次之,落叶树在氮的利用上是最低效的.     

Corrosive-wear characteristics of diamond-coated cemented carbide tools

Continuous milling tests with diamond-coated and uncoated cemented carbide tools and polycrystalline diamond tools were carried out on air-dried and wet melapi (Shorea sp.) and western redcedar (Thuja plicata D. Don). These tools were examined for corrosive-wear characteristics of the tool-edge appearance, cutting-edge profile, edge recession, and cutting-power consumption. The tool surfaces were observed with a scanning electron microscope and were analyzed by energy-dispersive X-ray spectroscopy. Based on these examinations, the occurrence of corrosive wear while cutting wet woods was confirmed for the uncoated and polycrystalline diamond tools. In contrast, the coated tools did not exhibit corrosive wear, nor did delamitation or wear of the diamond film occur with any of the work materials. The diamond-coated tools showed high resistance not only to mechanical wear but also to corrosive wear.The results of this work were presented at the 48th annual meeting of the Japan Wood Research Society, Shizuoka, April 1998     

Degradation of malathion and phenthoate by glutathione reductase in wheat germ

Residual malathion in wheat was estimated at a lower value when analysis was performed by extraction with acetone after addition of water to swell the wheat, according to the Japanese Bulletin Method. The supernatant of the wheat homogenate showed degradation not only of malathion but also of phenthoate. Malathion and phenthoate were not degraded by the boiled supernatant of the wheat homogenate. It was presumed for this reason that glutathione reductase (GR; EC 1.6. 4.2) in the wheat degraded malathion. The following results were obtained: (1) GR originating in wheat could degrade malathion and phenthoate. (2) The degradation of malathion by the GR was inhibited by excessive GSSG. (3) There was a high correlation between GR activity and malathion degradation activity of the supernatant of wheat homogenates. It is likely that GR acted on the specific structure of malathion and phenthoate, the S=P-S bond, and the blanch structure bonding with the sulfur atom. Following the above, extraction with acetone after addition of water (the Japanese Bulletin Method) should be replaced by extraction with pure organic solvent and without addition of water for swelling.     

中国南部九连山常绿阔叶林的区系组成和林分结构

在中国南部的九连山研究了天然的和择伐过的常绿阔叶林的树种组成和林分结构.主要构成树种是常绿阔叶的栲树(Castanopsis fargesii)、罗浮栲(C.fabri)、甜槠栲(C.eyrei)、米槠栲(C.carlesii)、南岭栲(C.fordii)、鹿角栲(C.lamontii)和木荷(Schima superba).常绿针叶树种的马尾松(Pinus massoniana)和杉木(Cunninghamia lanceolata)也是主要成分.马尾松在坡脊和坡的上部占优势.许多落叶阔叶树种,如光皮桦(Betula luminifera)和拟赤杨(Alniphyllum fortunei)以较低的优势与常绿阔叶树种共同出现.它们补丁状分布在择伐过的林分中.种内的分布格局和种间的空间分布关系表明,主要构成种之间的空间集中分布地的分离是在一个小的尺度上.     

Tolerance to low temperatures of Toxocara cati larvae in chicken muscle tissue

Infectivity of Toxocara cati larvae in muscle tissue of chickens after storage at 4°C and -25°C was assessed in a mouse bioassay to provide information on the risk of meat-borne toxocarosis. Muscle tissue samples of 30-day old T. cati infections were stored at 4°C for 14 and 28 days and at -25°C for 12, 24 and 48h, whereafter, larvae were released by digestion. For each experimental group, the released larvae were inoculated in six mice. After 15 days, mice were euthanized and larval burden was assessed by digestion. In the control group (no storage of the infected chicken meat), 47.9% of the inoculated larvae established in mice, whereas storage of meat at 4°C for 14 days or 28 days reduced the recovery to 24.1% or 3.3%, respectively. Muscle larvae exposed to -25°C for 12, 24 or 48h did not establish in the mice. The observation that larvae retain infective after refrigeration at exposure in 4°C for 28 days, emphasize the zoonotic potential of poultry meat as a causative agent of human toxocarosis.     

Influence of jam processing on the radical scavenging activity and phenolic content in berries

Six selected phenolic aglycons (caffeic and ellagic acids, kaempferol, quercetin, myricetin, and morin) in nine types of berries, and their changes as influenced by jam processing, have been evaluated using optimized HPLC with diode-array detection. The berry samples, fresh and after jam processing, were analyzed, and the total amounts of selected phenolics as aglycons were identified and determined by acid hydrolysis. Their contents in fresh and jam samples did not indicate appreciable changes; therefore, the influence of jam processing on these selected phenolics in berries was suggested to be small, and was mostly present in berries as several conjugated forms that were glycosylated, esterified, etc., in the samples. The total phenolic content of each sample was also determined by the Folin-Ciocalteu method. The three samples of each berry, namely fresh, jam, and acid hydrolysate of the berry, had similar total phenolic contents. On the other hand, the scavenging effect on the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical was measured, and acid hydrolysates showed stronger activity than that of the fresh and jam-processed samples for all of the berry types.     

Metabolism of grape seed polyphenol in the rat

The metabolism of grape seed polyphenol (GSP) has been investigated in rats by high-performance liquid chromatography analysis of the serum and urinary concentrations of the GSP metabolites (+)-catechin (CT), (-)-epicatechin (EC), 3'-O-methyl-(+)-catechin, and 3'-O-methyl-(-)-epicatechin. The serum concentration of these four metabolites reached a maximum 3 h after the oral administration of GSP. The urinary excretion of these GSP metabolites accounted for 0.254% (w/w) of the administered dose of GSP (1.0 g/kg), and the majority of these metabolites were excreted within 25 h of oral administration. The serum concentration and urinary excretion of these metabolites were also compared after the oral administration of different GSP monomers (gallic acid, CT, and EC), normal GSP, and the high molecular weight components of GSP (GSPH). No metabolites were detected in the serum of rats given GSPH. The urinary percentage excretion of the GSP metabolites derived from the respective monomers (CT or EC) did not vary with the administration of different substances (CT or EC, GSP, or GSPH). Taken together, these results suggest that only the monomers of GSP are absorbed and metabolized.