Daily rhythm in tyrosine concentration in human plasma: persistence on low-protein diets

The concentration of tyrosine in the plasma of normal males varies diurnally. It is lowest (9.5 +/- 0.35 micrograms per milliliter) between 0130 and 0230 hours and rises to a peak of 16.2 +/- 0.82 micrograms per milliliter by 1030 hours. This rhythm persists when subjects are maintained for 2 weeks on a diet that is very low in protein.     

The genomic sequence of the accidental pathogen Legionella pneumophila

We present the genomic sequence of Legionella pneumophila, the bacterial agent of Legionnaires' disease, a potentially fatal pneumonia acquired from aerosolized contaminated fresh water. The genome includes a 45-kilobase pair element that can exist in chromosomal and episomal forms, selective expansions of important gene families, genes for unexpected metabolic pathways, and previously unknown candidate virulence determinants. We highlight the genes that may account for Legionella's ability to survive in protozoa, mammalian macrophages, and inhospitable environmental niches and that may define new therapeutic targets.     

Antioxidative and hepatoprotective effects of Antrodia camphorata extract

Antrodia camphorata (A. camphorata) is well-known in Taiwan as a traditional Chinese medicine. The purpose of this study was to evaluate the ability of A. camphorata extracts to protect against oxidative stress in vitro and against carbon tetrachloride (CCl(4))-induced hepatic injury in vivo. An extract of A. camphorata inhibited nonenzymatic iron-induced lipid peroxidation in rat brain homogenates with an IC(50) value about 3.1 mg/mL. It also scavenged the stable free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH). The dose of the A. camphorata extract resulting in a decrease of 0.20 in the absorbance of DPPH was about 31 +/- 0.7 microg/mL. Furthermore, an A. camphorata extract dose-dependently (250-1250 mg/kg) ameliorated the increase in plasma aspartate aminotransferase (GOT) and alanine aminotransferase (GPT) levels caused by chronic repeated CCl(4) intoxication in mice. Moreover, A. camphorata extract significantly improved the CCl(4)-induced increase in hepatic glutathione peroxidase, reductase, and CCl(4)-induced decrease in superoxide dismutase activities. It also restored the decrement in the glutathione content and catalase activity of hepatic tissues in CCl(4)-intoxicated mice. Furthermore, it also dose-dependently inhibited the formation of lipid peroxidative products during CCl(4) treatment. Histopathological changes of hepatic lesions induced by CCl(4) were significantly ameliorated by treatment with an A. camphorata extract in a dose-dependent manner. These results suggest that A. camphorata extract exerts effective protection against chronic chemical-induced hepatic injury in vivo, by mediating antioxidative and free radical scavenging activities.     

Hibiscus protocatechuic acid or esculetin can inhibit oxidative LDL induced by either copper ion or nitric oxide donor

Oxidation of low-density lipoprotein (LDL) could increase the incidence of atherosclerosis. Previous studies have shown that copper and sodium nitroprusside (SNP) possess the ability to oxidize LDL in a dose-dependent condition. They increase the existing negative charge in LDL and increase the electrophoretic mobility. In this study, we used protocatechuic acid (PCA) and/or esculetin (ECT) to define the antioxidative activity in oxidative LDL by relative electrophoretic mobility (REM) and thiobarbituric acid-relative substances (TBARS). The data showed that ECT and PCA possessed stronger antioxidative activity than vitamin E in oxidative LDL. A previous study showed that the level of oxidative LDL can be determined by the cholesterol degradation and fragmentation of Apo B. Our results showed that Cu(2+)-mediated oxidative LDL can induce 31% cholesterol degradation and significant fragmentation of Apo B. Both PCA and ECT exhibited remarkable ability to rescue the cholesterol degradation and Apo B fragmentation. Taken together, both PCA and ECT showed strong potency to inhibit oxidative LDL induced by copper or an NO donor. Additionally, their nontoxic characteristics elevated the possibility for their use in the daily diet; and should further prevent atherosclerosis effectively.     

适宜原料压实度改善玉米秸秆厌氧干发酵特性

干发酵原料中固形物含量高,结构疏松,原料的压实度直接关系到发酵罐的利用率和生产成本。为了探讨原料压实度对厌氧干发酵过程的影响,该文以玉米秸秆粉为试验材料,研究了不同固形物含量(TS)条件下原料压实度对厌氧干发酵产气特性及物料特性变化的影响,结果表明:相同TS下,随着压实度的增加,日产气量(基于可挥发性固形物,VS)峰值降低且出峰时间略有滞后;原料压实度对累积产气量、日产气量变化趋势以及甲烷体积分数的影响不明显。基于发酵罐容积计算产气量时,原料压实度与日产气量峰值、累积产气总量以及累积甲烷产量均呈显著正相关。不同TS条件下的原料压实度对厌氧干发酵过程的影响程度不同,TS含量越高原料压实度对产气量的影响越明显。TS为20%和25%时,逐层压实发酵罐的单位容积累积产气量比自然填料罐分别提高了37.1%和60.2%。当发酵料初始TS为20%时,原料压实度的增加可促使物料中形成连续的液相,改善物料层间的传质,从而使发酵料上下层间的差异减小。当发酵料初始TS提高到25%时,原料压实度增加对传质特性无明显影响。综上所述,在该试验研究范围内,提高原料压实度可以保证玉米秸秆厌氧干发酵产气过程的正常进行,且可以显著提高发酵罐的容积利用率。该研究对厌氧干发酵原料压实度与发酵特性之间的关系进行了初步探讨,以期为有效提高厌氧干发酵罐的产能能力提供参考。     

半干旱黄土丘陵区典型抗旱造林整地技术集流效果研究

以宁南山区生态建设中推广应用的典型抗旱造林整地工程为研究对象,针对工程措施的集流效果进行研究,结果表明:实施"88542"集流造林整地工程,能够有效地改善土壤的水分状况,尤其在0-60 cm土层表现较为明显;工程措施的集流效果随地形的变化有所不同:随坡位自上而下改变,"88542"集流水平沟比集流坡面水分的增加率总体上呈增大趋势;随着坡长增大,工程措施对水分增加率也呈增大趋势;随坡度的增大,水平沟相对集流面的水分增加率也随之增加;随坡向不同,工程措施的集流效果则无明显差异;相对于工程措施的集流效果,坡长和坡度之间呈正相关关系,故在工程设计中,坡度越大,相应集流坡面长度就要缩短,反之坡度越缓,集流坡面长度就要增加.     

Evaluation of an enzyme-linked immunosorbent assay for detection of Eperythrozoon suis antibodies in swine.

An ELISA was developed and tested to detect antibodies to Eperythrozoon suis in swine. Results were compared with those of the indirect hemagglutination (IHA) test. Antigen isolated from swine heavily infected with E suis was used for both tests. Comparison of the ELISA with the IHA test revealed a significant (P less than 0.001) correlation between results. Of 114 samples obtained from 9 swine infected with E suis, 87.7% were seropositive (titer greater than or equal to 200) via the ELISA, and 80.7% were seropositive (titer greater than or equal to 20) via the IHA test. The sensitivity of the ELISA was greater than that of the IHA test. All blood samples obtained from specific-pathogen-free swine tested negative for E suis antibody. Cross-reactions were not observed between E suis antigen and antisera against various swine and cattle disease agents using ELISA. We concluded that the ELISA may be used for rapid and effective diagnosis of infection with E suis in swine.     

United States demand for hardwood plywood imports: A distributed lag model

A theoretical model of the United States demand for hardwood plywood imports was developed. Demand derives from activity in the construction industry where costs are minimised subject to a generalised Cobb-Douglas technology. This static model was then modified to reflect dynamic adjustments of imports to prices and housing starts. The resulting model was estimated with monthly data for the period January, 1974 to December, 1979. The choice of either c.i.f., f.a.s. or customs data did not significantly affect the statistical results. No significant substitution was apparent between imported hardwood plywood and domestic hardwood or softwood plywood. Import data appeared to be explained by expectations on housing starts and relative prices. Importers' expectations were represented by Cagan's adaptive expectations model and by Almon's polynomial lag equation. The latter model, relating imports to (i) housing starts and (ii) import prices, gave significantly better results. The maximum lag was of 9 months, with a mean lag of 4·5 months. The long-term elasticity of imports with respect to housing starts was estimated at 1·10 (±0·12). The long-term elasticity with respect to real price was ?1·98 (±0·24), using the price of all commodities as the deflator.     

Medial canthoplasty for epiphora in dogs: a retrospective study of 23 cases

The medical records of 23 dogs that underwent medial canthoplasty for treatment of epiphora were reviewed. The most prevalent breed encountered was the shih tzu. Other affected breeds included the Pekingese, Maltese, toy poodle, and pug. All dogs had epiphora associated with medial canthal trichiasis and/or entropion. Other ocular abnormalities included conjunctivitis, keratitis, pigmentary keratitis, corneal ulceration, globe prolapse, and nasal fold trichiasis. After medial canthoplasty, the epiphora resolved in all dogs.