中国对拉美农产品出口的影响因素分析及前景展望

利用引力模型,应用1995-2004年的贸易数据,考察了中国对拉美主要国家农产品出口的影响因素。计算结果显示,中国农产品供给能力、进口国GDP以及距离因素是中国对拉美农产品出口的重要影响因素。进一步的分析表明。中国对拉美主要贸易伙伴的农产品出口属于“贸易活跃”状况。其中乌拉圭的农产品市场已经得到较深入的开拓。而委内瑞拉、阿根延和厄瓜多尔等3个国家的出口潜力还需要进一步挖掘。     

Synthesis and Structure–Activity Relationships of Miticidal 4,5-Dihydropyrazole-5-thiones

A series of novel 4,5-dihydropyrazole-5-thiones (DHPs) was synthesised by treating the corresponding dihydropyrazolones with ‘Lawesson’s reagent and evaluated for miticidal activity against two-spotted spider mites (Tetranychus urticae Koch). Of these, 3-(4-chlorophenyl)-4,4-dimethyl-1-phenyl-4,5-dihydropyrazole-5-thione, 3-(4-chlorophenyl)-4-ethyl-4-methyl-1-phenyl-4,5-dihydropyrazole-5-thione, 3-(4-chlorophenyl)-1-phenyl-4,5-dihydropyrazole-5-thione-4-spirocyclopentane and 4,4-dimethyl-1-phenyl-3-(4-trifluoromethyl-phenyl)-4,5-dihydropyrazole-5-thione were highly active (pEC₅₀>4·0) and were more effective than the miticide dicofol (pEC₅₀=3·879), which has traditionally been used for the control of phytophagous mites. Structure–activity relationship (SAR) studies were performed on each position of the pyrazole ring of DHPs. The results indicated that the unsubstituted phenyl, 4-substituted phenyl and thioxo groups on the 1-, 3- and 5-positions of DHPs respectively were required for activity. Quantitative SAR studies using physicochemical parameters of substituents and the capacity factor k′ as a hydrophobicity index suggested that: (a) the activities of all types of DHPs examined were mainly dominated by hydrophobicity, (b) the bulkiness of 4-substituents of the 3-phenyl ring favoured the activity and (c) the log k′ optimum for all DHPs was 1·675, equivalent to a log P_ow value of c. 5·0.     

Predominant expression of growth hormone secretagogue receptor in the caudal lobe of chicken pituitary and parallel developmental increase in expression of pituitary GH and proventriculus ghrelin mRNA

To examine the involvement of ghrelin in growth hormone (GH) synthesis in the chicken pituitary, the regional distribution of GH secretagogue receptor (GHS‐R)/ghrelin receptor was investigated. Quantitative real‐time polymerase chain reaction (Q‐PCR) analysis revealed that the expression levels of GHS‐R and GH mRNA in the caudal lobe were about fourfold and sevenfold higher in the cephalic lobe of 7 day‐old chickens, respectively. Immunohistochemical analysis showed that GHS‐R immunoreactivity was more abundant in the caudal lobe than in the cephalic lobe, as was the case for GH immunoreactivity. By Q‐PCR, parallel increases were observed in the expression levels of ghrelin mRNA in the proventriculus and GH mRNA in the pituitary from embryonic day 17 to day 7 after hatching, whereas no significant change was found in the expression levels of GHS‐R mRNA in the pituitary during this period. These results suggest that proventriculus‐derived ghrelin may participate in pituitary GH synthesis by acting on its receptor during late embryonic development and the early post‐hatching period in chickens.     

Deuterium isotope effects on the formation of mercapturic acids from lindane in rats

Metabolism experiments with rats showed that significant isotope effects ($\text{k}{}_{\mathrm{<mtext>H</mtext>}}\text{k}{}_{\mathrm{<mtext>D</mtext>}}\text{= 2.4}\text{to}\text{3.5}$) were associated with the in vivo formation of dichloro and trichlorophenylmercapturic acids from a 1:1 mixture of normal and hexadeuterated lindane. This is evidence that rate-determining dehydrogenation and dehydrochlorination, both of which proceed with significant isotope effects, are essential in the pathway of dichloro- and trichlorophenylmercapturic acid formation from lindane. No significant primary isotope effects were associated ($\text{k}{}_{\mathrm{<mtext>H</mtext>}}\text{k}{}_{\mathrm{<mtext>D</mtext>}}\text{= 1.31 ± 0.17}$) with the formation of monochlorophenylmercapturic acid. This suggests that the 1,2-dechlorination to tetrachlorocyclohexene followed by glutathione conjugation is the probable pathway that produces this metabolite from lindane.     

Transverse shape analysis of xylem ground tissues by Fourier transform image analysis I: trial for statistical expression of cell arrangements with fluctuation

Periodic cell arrangements of tracheids in Cryptomeria japonica and Agathis sp., and that of wood fibers in Magnolia obovata were examined by Fourier transform image analysis (FTIA). The angular distribution functions on power spectral patterns (PSPs) transformed from the dot maps were traced. As well as this conventional method, we developed the line convolution method and domain transformation for more correct analysis of radial and tangential arrangements. Cell arrangements became clear in Cryptomeria and Agathis. Fluctuations were expressed by the standard deviation (σ) or the relative standard deviation (σ_r) so that we could compare the characteristics of both woods. In Cryptomeria, the most provable distance between tracheids along radial files was 36.7 µm with 17% fluctuation, whereas the tangential interval was 28.3 µm with σ_r of 24%. In Agathis, the radial diameter was 35.1 µm with σ_r of 23% and the tangential interval was 41.5 µm with σ_r of 23%. In Magnolia, the maximal periodicity of wood fibers was 15.8 µm and 20.5 µm along and between radial files, respectively, although the fluctuations could not be estimated because of the remarkable interruptions by numerous vessels.     

Two lignan rhamnosides from birch leaves

The extractives of shirakamba (Betula platyphylla Sukatchev var.japonica Hara) leaves were investigated. Two lignan glycosides were isolated, and their structures were elucidated to be 1-(4-hydroxy-3-methoxyphenyl)-2-[1-(3--l-rhamnopyranosyloxypropyl)-3-hydroxyphenoxy]-1,3-propanediol (I) and a new 2,3-dihydro-2-arylbenzofuran configuration neolignan,cis-2,3-dihydro-2-(4--l-rhamnopyranosyloxy-3-methoxyphenyl)-3-hydroxymethyl-7-hydroxy-5-benzofuranpropanol (II). These neolignan rhamnosides were newly found in shirakamba.     

Identification of marker genes for intestinal immunomodulating effect of a fructooligosaccharide by DNA microarray analysis

Prebiotic fructooligosaccharides are noted for their intestinal immunodulating effects, and the identification of markers for the effects is a matter of great concern. This study aimed to identify marker genes for physiological effects of a particular fructooligosaccharide (FOS) on a host animal and also to define the target of its function in the small intestine. DNA microarray technology was used to screen candidate marker genes, and comprehensive changes in gene expressions in the ileum of mice fed with FOS were investigated. One of the major physiological effects of FOS was intestinal immunomodulation. Marker genes were then identified for major histocompatibility complex classes I and II, interferon, and phosphatidylinositol metabolites. Also, the ileum was segmented into Peyer's patch (PP) and the other ileal organ (DeltaPP), and these were analyzed by quantitative RT-PCR method, with the result that the site for recognizing the FOS function was the DeltaPP rather than the PP. This is the first paper showing the markers for the physiological effects of FOS in the small intestine at gene expression level. Applying these marker genes would make it possible to clarify the mechanisms of how the administration of dietary FOS and associated changes in the intestinal environment are recognized by host organisms as well as how its immunomodulating effects are expressed in the body.     

Cardiovascular effects of continuous propofol infusion in horses

We examined the influence of propofol infusion on cardiovascular system at the rate of 0.14, 0.20 and 0.30 mg/kg/min in six adult Thoroughbred horses. The cardiovascular parameters were heart rate (HR), mean arterial pressure (MAP), mean right atrial pressure (MRAP), stroke volume (SV), cardiac output (CO), systemic vascular resistance (SVR), pre-ejection period (PEP) and ejection time (ET). In order to keep the ventilation conditions constantly, intermittent positive pressure ventilation was performed, and the partial arterial CO(2) pressure was maintained at 45 to 55 mmHg during maintenance anesthesia. SV showed a significant dose-dependent decrease however, CO did not show significant change. SVR decreased significantly at higher dose. PEP was prolonged and PEP/ET increased significantly at the highest dose. From these results, it became clear that SV decreases dose-dependently due to decrease of cardiac contractility during anesthesia with continuous propofol infusion in horses. On the other hand, since MAP and CO did not show significant changes, total intravenous anesthesia with propofol was suggested to be suitable for long-term anesthesia in horses.     

Development and biological properties of a new live attenuated mumps vaccine

To develop a new live attenuated mumps vaccine, a wild mumps Y7 strain isolated from a patient who developed mild parotitis was treated with nitrosoguanidine and ultraviolet, followed by selection of a temperature-sensitive clone. The selected clone, Y125, showed stable temperature-sensitivity in Vero cells. Intraspinal inoculation of marmosets with the Y125 produced only minimal histopathological changes, while intracerebral inoculation of neonatal rats revealed that the Y125 did not cause hydrocephalus. Both these effects of the Y125 were similar to those of the non-neurovirulent Jeryl Lynn strain. Furthermore, subcutaneous inoculation of the Y125 induced high levels of neutralizing antibodies in all Cercopithecus monkeys examined. Although the safety and immunogenicity should be confirmed in further field trials in humans, the present results indicate that the Y125 could be a promising vaccine candidate.     

Age-related Histological Findings in the Pineal Gland of Crl:CD(SD) Rats

To provide background data as the pathologic basis, the pineal glands of 190 male and 193 female Crl:CD(SD) rats at ages of 0–7, 51–58, 70–85 and 111 weeks were examined histologically in this study. Mineralization and fibrosis were common findings in the aged rats, whereas they were rarely found in the young ones; mineralization was present in 7, 44, 67 and 79% of males and in 0, 32, 67 and 79% in females, and fibrosis was present in 0, 29, 48 and 44% of males and 0, 18, 40 and 35% of females at ages of 0–7, 51–58, 70–85 and 111 weeks, respectively. Striated muscle fiber appeared regularly in the fibrosis region from 51–58 weeks of age when fibrosis increased, while the origin of this fiber remained unclear. Vacuolation of pineal cells also increased with age in both sexes, though the total incidence was low. There was a low incidence of lymphocytic infiltration in both sexes, but this was not related to age.