Mitogenic effect contributes to increased virulence of Streptococcus suis sequence type 7 to cause streptococcal toxic shock-like syndrome

Streptococcus suis serotype 2 sequence type 7 strains emerged in 1996 and caused a streptococcal toxic shock-like syndrome in 1998 and 2005 in China. Evidence indicated that the virulence of S. suis sequence type 7 had increased, but the mechanism was unknown. The sequence type 7 strain SC84, isolated from a patient with streptococcal toxic shock-like syndrome during the Sichuan outbreak, and the sequence type 1 strain 31533, a typical highly pathogenic strain isolated from a diseased pig, were used in comparative studies. In this study we show the mechanisms underlying cytokine production differed between the two types of strains. The S. suis sequence type 7 strain SC84 possesses a stronger capacity to stimulate T cells, naive T cells and peripheral blood mononuclear cell proliferation than does S. suis sequence type 1 strain 31533. The T cell response to both strains was dependent upon the presence of antigen-presenting cells. Histo-incompatible antigen-presenting cells were sufficient to provide the accessory signals to naive T cell stimulated by the two strains, indicating that both sequence type 7 and 1 strains possess mitogens; however, the mitogenic effect was different. Therefore, we propose that the difference in the mitogenic effect of sequence type 7 strain SC84 compared with the sequence type 1 strain 31533 of S. suis may be associated with the clinical, epidemiological and microbiological difference, where the ST 7 strains have a larger mitogenic effect.

An intelligent mobile vehicle navigator based on fuzzy logic and reinforcement learning

In this paper, an alternative training approach to the EEM-based training method is presented and a fuzzy reactive navigation architecture is described. The new training method is 270 times faster in learning speed; and is only 4% of the learning cost of the EEM method. It also has very reliable convergence of learning; very high number of learned rules (98.8%); and high adaptability. Using the rule base learned from the new method, the proposed fuzzy reactive navigator fuses the obstacle avoidance behaviour and goal seeking behaviour to determine its control actions, where adaptability is achieved with the aid of an environment evaluator. A comparison of this navigator using the rule bases obtained from the new training method and the EEM method, shows that the new navigator guarantees a solution and its solution is more acceptable.

Quantitation of SU11248, an oral multi-target tyrosine kinase inhibitor, and its metabolite in monkey tissues by liquid chromatograph with tandem mass spectrometry following semi-automated liquid–liquid extraction

SU11248 is a potent inhibitor of PDGFR, VEGFR, KIT, and Flt3, and is currently under Phase I clinical evaluation as an anticancer drug. A sensitive and specific analytical method for the quantitation of SU11248 and its metabolite in several monkey tissues (liver, kidney, brain and white fat) using LC-MS-MS following semi-automated liquid-liquid extraction (LLE) was developed and validated. Amounts of 50 mg of tissue were homogenized using an ultrasonic processor. After addition of the stable labelled internal standard (IS) and ammonium hydroxide (0.3%), samples were extracted with 2.5 ml of tert-butyl methyl ether. Following centrifugation, aliquots of 1.8 ml of the organic phase were transferred into a 96-well plate. The Packard Multiprobe II robotic liquid handler was used to perform all steps mentioned above. The organic phase was dried and the residue was reconstituted with 800 microl of 15 mM ammonium formate buffer solution (pH 3.25) using a Tomtec Quadra 96 workstation. Aliquots of 10 microl of the resulting solution were injected into the LC-MS-MS system. A Symmetry Shield C8 column (50 mm x 2.1 mm, 3.5 microm) was used to perform the chromatographic analysis. The mobile phase was 15 mM ammonium formate buffer solution (pH 3.25)-acetonitrile (74:26 (v/v)) with a flow-rate of 0.35 ml/min. Retention times of the metabolite and SU11248 were about 2.5 and 3.5 min, respectively. Total cycle time was 5 min. MS detection used the Applied Biosystems-MDS Sciex API 3000 with TurbolonSpray interface and multiple reaction monitoring (MRM) operated in positive ion mode. The method was validated for both compounds over the calibration range of about 2 and 2000 ng/g. The suitability and robustness of the method for in vivo samples were confirmed by analysis of monkey tissues from animals dosed with SU11248.

[Preparation and analysis of pure type II collagen from porcine articular cartilage]

This investigation was aimed at the preparation of pure type II collagen from porcine articular cartilage and the feasible method for producing type II collagen in bulk. After dispersal of the porcine articular cartilage, the proteoglycans were extracted by guanidinium hydrochloride and dissolved by pepsin in acid solvent. The contaminants including denatured and degraded protein and other collagen was removed via the repeated procedure of purification. For obtaining the purer type II collagen, the chromatography with sepharose H. P. Column was also used. The purity of the sample was compared with the type II collagen produced by Sigma Company. Both type II collagens were characterized by SDS-PAGE electrophoresis, amino acid analysis and maximal violet chromatography, and all of the results accorded with the standard photograph in the references. The purity of the sample was higher than that of the product of Sigma Company. This prepared collagen of type II is a product of high purity. The raw materials are the common porcine articular cartilage, which is rich in resource and low in cost. Therefore, it is suitable to produce type II collagen in batches.

Room-temperature ionic liquids: a novel versatile lubricant

Alkylimidazolium tetrafluoroborates are promising versatile lubricants for the contact of steel/steel, steel/aluminium, steel/copper, steel/SiO2, Si3N4/SiO2, steel/Si(100), steel/sialon ceramics and Si3N4/sialon ceramics; they show excellent friction reduction, antiwear performance and high load-carrying capacity.

[The transferability of acetochlor and butachlor in soil]

The transferability of acetochlor and butachlor in soil was studied by soil thin layer chromatography. Acetochlor and butachlor were dropped on the glass plate and spreaded soil on the glass plate was collected per 2 cm, then acetochlor and butachlor were analyzed quantitatively by HPlC. When river water was as the spread solution, Rf(relative flow) of acetochlor and butachlor in the Haidian loam were 0.116 and 0.031 respectively, Rf of acetochlor and butachlor in the Baiyangdian sandy loam were 0.147 and 0.032 respectively. When 30 mg.L-1 dodecylbenzene sulfonic acid sodium salt solution was as the spread solution, Rf of acetochlor and butachlor in the Haidian loam were 0.159 and 0.034 respectively. Acetochlor's transferability was weak and the gradation of its transferability was II grade, while butachlor's was more weak and the gradation was I grade. Anionic surfactant solution can promote pesticides to transfer. Cationic surfactant solution can impede pesticides to transfer.

Prevalence of iron transport gene on pathogenicity-associated island of uropathogenic Escherichia coli in E. coli O157:H7 containing Shiga toxin gene

Uropathogenc Escherichia coli (UPEC) CFT073 has a pathogenicity-associated island (PAI(CFT073)), which causes pyelonephritis and cystitis. Using PCR method, we found the prrA gene of PAI(CFT073) in E. coli O157:H7 EDL933. Further detailed PCR screening of 38 open reading frames, the right and left junction sequences of PAI(CFT073), revealed that it is the prrA-modD-yc73-fepC gene cluster but not the PAI(CFT073) present in E. coli O157:H7 EDL933. A rapid preliminary analysis suggested that the prrA-modD-yc73-fepC gene cluster of the PAI(CFT073), is present in 43 strains of E. coli O157:H7 containing Shiga toxin (Stx) gene but absent in 19 strains of E. coli O157:H7 without Stx gene. A strict co-occurrence of the prrA-modD-yc73-fepC gene cluster and Stx genes was observed, regardless of their origin. The prrA-modD-yc73-fepC gene cluster encode proteins probably involved in iron uptake system, which strongly suggests the importance of iron metabolism in the Stx-mediated virulence. In addition, the prrA-modD-yc73-fepC gene cluster may be used as a diagnostic marker to distinguish E. coli O157:H7 strains containing Stx gene from that without Stx gene, and possibly to quickly detect other pathogenic gram-negative bacteria containing the Stx gene.

Dynamics and mechanism of ultraviolet photolysis of atrazine on soil surface

The photolysis of atrazine in the soil surface under UV light and the factors affecting this has been studied. A rate constant of 0.09-0.17 min-1, photolytic depth of 0.1-0.3 mm and half-life of 4-8 min were determined. The results show that soil granularity, pH, humidity, organic content, humic acid and surface-active agents could affect the photolysis of atrazine in soil. GC-MS showed three photolytic products: 1-sec-butyl-4,4-diethyl-1-tetrazene, N2,N4-diethyl-6-methyl-1,3,5-triazine-2,4-diamine and 6-chloro-N2-propyl-1,3,5-triazine-2,4-diamine. The mechanism of the photolytic process is discussed.

Oral HCFU for prevention of hepatic metastasis in an experimental colorectal carcinoma

BACKGROUND

An animal experimental study was performed to clarify the preventive effect of oral HCFU (1-hexylcarbamoyl-5-fluorouracil) on hepatic metastasis.

MATERIALS AND METHODS

A total of 180 BALB/C mice received intraportal injection of Colon26 cancer cells followed by oral daily administration of HCFU to 5 groups divided according to the dose of HCFU, ranging from 0 (controls) to 7.5 mg/Kg for 21 days. These groups were independently assigned to 3 sets to investigate survival rates and degree of hepatic metastasis.

RESULTS

Mean survivals in the treated groups were statistically longer than the controls except the 7.5 mg/Kg group. HCFU 7.5 and 5 mg/Kg groups showed the minimum liver weight on the 12th and 16th day, respectively these were significantly smaller than those of controls (p < 0.0001 in both).

CONCLUSION

It is considered that oral HCFU could effectively suppress hepatic metastasis of the colon26 cancer cells and prolong the life of animals. This finding suggests the promising clinical application of oral HCFU for colorectal cancer after curative resection.