Metabolites in Blood for Prediction of Bacteremic Sepsis in the Emergency Room

A metabolomics approach for prediction of bacteremic sepsis in patients in the emergency room (ER) was investigated. In a prospective study, whole blood samples from 65 patients with bacteremic sepsis and 49 ER controls were compared. The blood samples were analyzed using gas chromatography coupled to time-of-flight mass spectrometry. Multivariate and logistic regression modeling using metabolites identified by chromatography or using conventional laboratory parameters and clinical scores of infection were employed. A predictive model of bacteremic sepsis with 107 metabolites was developed and validated. The number of metabolites was reduced stepwise until identifying a set of 6 predictive metabolites. A 6-metabolite predictive logistic regression model showed a sensitivity of 0.91(95% CI 0.69–0.99) and a specificity 0.84 (95% CI 0.58–0.94) with an AUC of 0.93 (95% CI 0.89–1.01). Myristic acid was the single most predictive metabolite, with a sensitivity of 1.00 (95% CI 0.85–1.00) and specificity of 0.95 (95% CI 0.74–0.99), and performed better than various combinations of conventional laboratory and clinical parameters. We found that a metabolomics approach for analysis of acute blood samples was useful for identification of patients with bacteremic sepsis. Metabolomics should be further evaluated as a new tool for infection diagnostics.     

Characterization of lignin peroxidase-encoding genes from lignin-degrading basidiomycetes

Two closely linked lignin peroxidase (LPO)-encoding genes (lpo) from Phanerochaete chrysosporium were isolated. Nucleotide sequence studies indicated that the two genes are separated by 1.3 kb of flanking DNA and transcribed in opposite directions. Cloned P. chrysosporium lpo gene probes have been shown to hybridize to multiple sequences present in the DNAs of the white-rot fungi, Bjerkandera adusta, Coriolus versicolor and Fomes lignosus, but no hybridization was detected with DNA from Pleurotus ostreatus. Thus, lpo gene families appear to be common in a number of lignin-degrading basidiomycetes, some of which have not yet been shown to produce LPO proteins.     

Structure of phosphate-free ribonuclease A refined at 1.26 A

The structure of phosphate-free bovine ribonuclease A has been refined at 1.26-A resolution by a restrained least-squares procedure to a final R factor of 0.15. X-ray diffraction data were collected with an electronic position-sensitive detector. The final model consists of all atoms in the polypeptide chain including hydrogens, 188 water sites with full or partial occupancy, and a single molecule of 2-methyl-2-propanol. Thirteen side chains were modeled with two alternate conformations. Major changes to the active site include the addition of two waters in the phosphate-binding pocket, disordering of Gln-11, and tilting of the imidazole ring of His-119. The structure of the protein and of the associated solvent was extensively compared with three other high-resolution, refined structures of this enzyme.     

Virulence plasmid-associated autoagglutination in Yersinia spp.

The autoagglutination of Yersinia enterocolitica was dependent on the presence of the virulence plasmid and on the active growth of bacteria in tissue culture media at 37 degrees C. Cultures with a high initial concentration of bacteria failed to autoagglutinate , indicating that synthesis of new virulence plasmid-associated surface factors was essential for autoagglutination. The synthesis of a plasmid-encoded polypeptide (molecular weight, 240,000), designated P1, that could be dissociated under strongly reducing conditions into subunits of 52,500 daltons was found to be correlated with autoagglutination. Further, a strain of Yersinia pseudotuberculosis [ YPIII ( PIB102 )], which has Tn5 inserted within the structural gene of P1 that prevents the synthesis of P1, failed to autoagglutinate , in contrast to the wild-type strain, strongly indicating that P1 is involved in this phenomenon. It was also found by immunoblotting that in addition to the common response to temperature, the P1 proteins of Y. enterocolitica and Y. pseudotuberculosis were immunologically related.     

Multiple conformations of amino acid residues in ribonuclease A

The highly refined 1.26 A structure (R = 0.15) of phosphate-free bovine pancreatic ribonuclease A was modeled with 13 residues having discrete multiple conformations of side chains. These residues are widely distributed over the protein surface, but only one of them, Lys 61, is involved in crystal packing interactions. The discrete conformers have no unusual torsion angles, and their interactions with the solvent and with other atoms of the protein are similar to those residues modeled with a single conformation. For three of the residues--Val 43, Asp 83, and Arg 85--two correlated conformations are found. The observed multiple conformations on the protein surfaces will be of significance in analyzing structure-function relationships and in performing protein engineering.     

Energy metabolism of medium-chain triglycerides versus carbohydrates during exercise

Medium-chain triglycerides (MCT) are known to be rapidly digested and oxidized. Their potential value as a source of dietary energy during exercise was compared with that of maltodextrins (MD). Twelve subjects exercised for 1 h on a bicycle ergometer (60% VO2 max), 1 h after the test meal (1MJ). The metabolism of MCT was followed using 1-13C-octanoate (Oc) as tracer and U-13C-glucose (G) was added to the 13C-naturally enriched MD. After MCT ingestion no insulin peak was observed with some accumulation of ketone bodies (KB), blood levels not exceeding 1 mM. Total losses of KB during exercise in urine, sweat and as breath acetone were small (less than 0.2 mmol X h-1). Hence, the influence of KB loss and storage on gas exchange data was negligible. The partition of fat and carbohydrate utilization during exercise as obtained by indirect calorimetry was practically the same after the MCT and the CHO meals. Oxidation over the 2-h period was 30% of dose for Oc and 45% for G. Glycogen decrements in the Vastus lateralis muscle were equal. It appears that with normal carbohydrate stores, a single meal of MCT or CHO did not alter the contribution of carbohydrates during 1 h of high submaximal exercise. The moderate ketonemia after MCT, despite substantial oxidation of this fat, led to no difference in muscle glycogen sparing between the diets.     

Insect immunity: two proteinase inhibitors from hemolymph of Locusta migratoria.

Two protease inhibitors were isolated from the plasma of Locusta migratoria and sequenced. They were 35 and 36 amino acids long and revealed very little similitude for the protease inhibitors isolated from other arthropods. They inhibit the proPhenoloxidase Phenoloxidase proteolytic activation cascade in hemocyte extracts of the same insect. This inhibiting activity resulted in a lower production of PO, a key enzyme for the defence mechanism in arthropods. Both peptides however showed a strong in vitro inhibiting activity toward alpha-chymotrypsin and elastase, LMCI I inhibits the human leukocyte enzyme while LMCI II mostly the pancreatic one, a difference explainable on the basis of the active site sequence changes.     

以异源四倍体体细胞杂种为父本杂交培育三倍体柑桔植株的研究

以 3个柑桔原生质体融合而来的四倍体体细胞杂种为父本 ,与二倍体单胚性种柚子 (Citrusgrandis)以及单多胚混合型品种“华农本地早”桔 (C.reticulata)有性杂交 ,授粉后 90 d,发现种子干瘪 ,大部分种子的胚败育。将干瘪种子在 MT附加 1mg/L GA3 或 50 0 mg/L麦芽浸出物的培养基中 ,经培养抢救 ,有 2 5.6%的种子萌发成苗或继续进行胚的生长 ,后者进一步诱导能形成丛芽 ,经试管嫁接或诱导生根形成完整植株。共获得 6个组合 73棵完整植株 ,染色体数检查表明 ,2 0株为三倍体 (2 n=3x=2 7) ,32株为二倍体 (2 n=2 x=18) ,8株为非整倍体 ,其它 13株还有待于进一步检查。     

鹤顶兰胚囊发育过程中微管变化的共焦显微镜观察

光镜的观察确定了鹤顶兰（Ｐｈａｉｕｓ ｔａｎｋｅｒｖｉｌｌｉａｅ （Ａｉｔｏｎ） Ｂｌ．）胚囊发育属单孢子蓼型。应用免疫荧光标记技术及共焦镜观察了胚囊发育过程中微管分布的变化。当孢原细胞初形成时,细胞内的微管呈网状分布。之后,孢原细胞体积增大发育为大孢子母细胞。大孢子母细胞延长,进入减数分裂Ⅰ。微管由分裂前的网状分布变为辐射状排列。二分体的两个细胞内的微管分布一样,呈辐射状。四分体的近珠孔端的３ 个大孢子解体,细胞内的微管消失。靠合点端的功能大孢子内有许多微管呈网状分布。当功能大孢子进入第一次有丝分裂时,细胞内的微管由网状变为辐射状,从核膜伸展至周质。再经两次有丝分裂形成八核胚囊。在核分裂之前微管一般是呈网状分布并紧包围着核。在分裂期间二核和四核胚囊都呈极性现象,微管系统也呈极性分布。微管在八核胚囊内的分布变化情形特别复杂。首先,八核分别作不同程度的移动,其中两个核移向胚囊中央,珠孔端和合点端的３ 个核分别互相靠拢,形成３ 个区,即中央区、反足区和卵器区。胚囊未形成区时,８ 个核都被网状分布的微管包围着。当胚囊明显分成区时,反足区内的微管仍作网状分布。中央区的微管分布则趋疏松,形成篮形结构,包围着液泡和两个极核。在