Showing papers by "Lei Zhang published in 2009"

Microbial production of 4-hydroxybutyrate, poly-4-hydroxybutyrate, and poly(3-hydroxybutyrate-co-4-hydroxybutyrate) by recombinant microorganisms

Abstract: 4-Hydroxybutyrate (4HB) was produced by Aeromonas hydrophila 4AK4, Escherichia coli S17-1, or Pseudomonas putida KT2442 harboring 1,3-propanediol dehydrogenase gene dhaT and aldehyde dehydrogenase gene aldD from P. putida KT2442 which are capable of transforming 1,4-butanediol (1,4-BD) to 4HB. 4HB containing fermentation broth was used for production of homopolymer poly-4-hydroxybutyrate [P(4HB)] and copolymers poly(3-hydroxybutyrate-co-4-hydroxybutyrate) [P(3HB-4HB)]. Recombinant A. hydrophila 4AK4 harboring plasmid pZL-dhaT-aldD containing dhaT and aldD was the most effective 4HB producer, achieving approximately 4 g/l 4HB from 10 g/l 1,4-BD after 48 h of incubation. The strain produced over 10 g/l 4HB from 20 g/l 1,4-BD after 52 h of cultivation in a 6-L fermenter. Recombinant E. coli S17-1 grown on 4HB containing fermentation broth was found to accumulate 83 wt.% of intracellular P(4HB) in shake flask study. Recombinant Ralstonia eutropha H16 grew to over 6 g/l cell dry weight containing 49 wt.% P(3HB-13%4HB) after 72 h.

Gsα signalling suppresses PPARγ2 generation and inhibits 3T3L1 adipogenesis

Abstract: Since TSH receptor (TSHR) expression increases during adipogenesis and signals via cAMP/phospho-cAMP-response element binding protein (CREB), reported to be necessary and sufficient for adipogenesis, we hypothesised that TSHR activation would induce preadipocyte differentiation. Retroviral vectors introduced constitutively active TSHR (TSHR*) into 3T3L1 preadipocytes; despite increased cAMP (RIA) and phospho-CREB (western blot) there was no spontaneous adipogenesis (assessed morphologically, using oil red O and QPCR measurement of adipogenesis markers). We speculated that Gβγ signalling may be inhibitory but failed to induce adipogenesis using activated Gsα (gsp*). Inhibition of phosphodiesterases did not promote adipogenesis in TSHR* or gsp* populations. Furthermore, differentiation induced by adipogenic medium with pioglitazone was reduced in TSHR* and abolished in gsp* expressing 3T3L1 cells. TSHR* and gsp* did not inactivate PPARγ (PPARG as listed in the HUGO database) by phosphorylation but expression of PPARγ1 was reduced and PPARγ2 undetectable in gsp*. FOXO1 phosphorylation (required to inactivate this repressor of adipogenesis) was lowest in gsp* despite the activation of AKT by phosphorylation. PROF is a mediator that facilitates FOXO1 phosphorylation by phospho-Akt. Its transcript levels remained constantly low in the gsp* population. In most measurements, the TSHR* cells were between the gsp* and control 3T3L1 preadipocytes. The enhanced down-regulation of PREF1 (adipogenesis inhibitor) permits retention of some adipogenic potential in the TSHR* population. We conclude that Gsα signalling impedes FOXO1 phosphorylation and thus inhibits PPARγ transcription and the alternative promoter usage required to generate PPARγ2, the fat-specific transcription factor necessary for adipogenesis.

GLS/IL-12-modified Mycobacterium smegmatis as a novel anti-tuberculosis immunotherapeutic vaccine.

Abstract: OBJECTIF: Etudier les effets et les mecanismes de Mycobacterium smegmatis recombinant (rMS) porteur du pZM03 (un plasmide de co-expression encodant la granulysine [GLS] humaine et l'interleukine 12 [IL-12] murin) sur l'infection murine par M. tuberculosis. SCHEMA: Des souris specifiques BALB/c infectees par M. tuberculosis ont ete traitees respectivement au moyen de solution saline isotonique, de M. smegmatis, de pZM03 et de rMS. Les nombres de bacteries viables dans les poumons et les rates ont ete comptes pour observer les effets therapeutiques. Les niveaux de IL-12 et de l'interferon gamma (IFN-γ) dans le serum ainsi que ceux d'IFN-γ et du facteur de necrose tumorale alpha (TNF-α) liberes par les lymphocytes spleniques ont ete examines pour etudier la reponse de type T-helper 1 (Th1). Les IgA secretoires (SigA) dans le lavage broncho-alveolaire ont ete mesures pour examiner l'immunite au niveau des muqueuses. On a traite les poumons et les rates en vue d'un examen anatomopathologique. RESULTATS: Dans le groupe rMS, on a observe un nombre significativement reduit d'unites formant colonies par comparaison avec les autres groupes. L'expression de la GLS dans le tissu et un niveau accru d'IL-12, d'IFN-γ, de TNF-α et de SIgA ont ete observes dans le groupe rMS. Les modifications anatomopathologiques dans les poumons du groupe rMS sont localisees, alors qu'elles sont etendues dans le groupe controle. CONCLUSION: Le rMS a des effets immunotherapeutiques qui sont associes avec un glissement vers une reponse de type Th1 et avec l'activite antibacterienne du GLS.

Low levels of serum vitronectin associated with clinical phases in patients with hemorrhagic fever with renal syndrome

Abstract: β3 integrin has been identified as a cellular receptor for Hantaan virus which causes hemorrhagic fever with renal syndrome (HFRS). As one of the ligands of β3 integrin, vitronectin (VN) may be altered in HFRS. In this study, changes of serum VN levels were determined in 112 patients with HFRS and 30 age- and sex-matched healthy controls by quantitative sandwich enzyme immunoassay. The levels of serum VN were analyzed in patients at various phases of HFRS and with different severity of clinical types. Serum VN levels in patients with HFRS, at all clinical phases except the convalescent phase, were significantly decreased compared with those in the controls (P 0.05). These results suggest that VN level was altered during the course of HFRS and chronological changes of serum levels of VN may correlate with the evolution of the disease.

Kinetics of major histocompatibility class I antigen presentation in acute infection

Abstract: Ag presentation within the regional lymph node is crucial for the initiation of CD8+ T cell responses following viral infection. The magnitude and quality of the CD8+ T cell response are regulated by the interplay between the size of the APC population and duration of Ag presentation. To understand how these parameters are finely regulated during an immune response, we have investigated the dynamics of Ag presentation in influenza A virus and HSV-1 infection. In both infections, APC production was calculated to occur over the first few days of infection, after which there was slow exponential decay over a period of up to 2 wk. This production rate is most likely determined by the Ag availability and recruitment and/or maturation rate of dendritic cells. APC production was found to closely parallel lymph node cell recruitment in both infections. This was greatest in the first 6 h of infection for HSV and over the second and third day for influenza. In HSV infection, the peak production also coincides with peak viral levels. By contrast, in influenza infection, APC production ceased between the third and fourth day despite the presence of high levels of virus until 5 days after infection. These analyses demonstrate that two quite different self-limiting infections generate the APC necessary to drive T cell responses early in infection at different rates. Understanding how such contrasting kinetics of Ag presentation impacts on the growth and size of developing protective T cell populations has important implications for the design of vaccines and immunotherapies.

Method for producing 3-hydracrylic acid

Abstract: The invention discloses a method for producing 3-hydracrylic acid. The method is characterized by taking 1,3-propylene glycol as a raw material, and producing the 3-hydracrylic acid by microbes which express 1,3-propylene glycol dehydrogenase and aldehyde oxidase. The microbes which express the 1,3-propylene glycol dehydrogenase and the aldehyde oxidase are microbes which naturally express the 1,3-propylene glycol dehydrogenase and the aldehyde oxidase, or recombinant microbes which can express the 1,3-propylene glycol dehydrogenase and the aldehyde oxidase and are obtained by transferring coding gene of 1,3-propylene glycol dehydrogenase and coding genes of the aldehyde oxidase into a microbe host. By the method, the 1,3-propylene glycol is taken as the raw material, content of the 3-hydracrylic acid per liter of a culture medium is up to 0.24-12.1g.

Reinforcement wire wound inner concave beam frame

Abstract: The invention provides a reinforcement wire wound inner concave beam frame. Sections of an upper beam 1 and a lower beam 2 are all in inversely concave shapes; an inner margin of the beam comprises a base plane 6 and two transition arc surfaces 5; an outer margin 4 of the beam and an inner margin arc 5 are positioned on the same side of the diameter 7 of an outer margin arc of the beam. The inner concave beam of the frame has simple structure, is easy to be processed and assembled, effectively utilizes space, reduces the overall height of the frame, improves the overall stability and lightens the weight. The inner margin structure of the beam, which is determined suitable, can ensure that the beam has relatively small tensile stress under any state, thereby improving the fatigue strength of the beam, being a comparatively ideal beam structure frame with controllable low tensile stress and having wide application prospect.