The thermooxidative degradtion of ethylene oxide and tetra-hydrofuran (EO-THF) co-polyether has been studied by electron spin resonance(ESR),Fourier transform infrared (FT-IR) and nuclear magnetic resonance (NMR) spectroscopy. The initial degradation site was found to be at the α-carbon of the ether bond. Two free radicals which derived from dehydrogenation and oxygen addition were successfully detected by spin-trapping technique which used α-phenyl-N-tert-butyl nitrone (PBN) as spin trap. Both FT-IR and NMR have been used tofollow structural changes of the copolyether during degradation. Nearly 20 product frngnents including formate,carbonate,methyl,alcohol,methylene-dioxy,hydroperoxide and semiformal have been characterized by 1 D and 2 D NMR.The thermooxidtion of co-polyether preferred to occur on the THF units especially at the alternating linkage of EO and THF.Antioxidant (BHT) not only retarded the thermooxidation but also modified the degradation products with less ester and methylene-dioxy groups but more hydroxyl and methyl groups.

Objective For decreasing the infected rate,the prevention and cure methods of intracranial infections following posterior fossa craniotomy were study. Methods Twenty-eight patients with the intracranial infections following posterior fossa craniotomy were examined by lumbar puncture,and analyzed cerebrospinal fluid with routine examination and reference to the bacteriological data and drug sensitive tests. All the patients were treated with high dosage sensitive antibiotics, and draining continually the infected cerebrospinal fluid by lumbar puncture catheterization and injected small dosages of antibiotics into intraspinal for most cases. Results Twenty-eight patients had intracranial hypertension by lumbar puncture examination, outcome of cerebrospinal fluid culture indicated that 17 cases had bacteria growth and 11 cases had no bacteria. The intracranial infection was controlled effectively,and 96.4%(27 cases) were cured, 1 case dead of systemic failure. Conclusions Strict aseptic techniques,reduce operative time,decrease intracranial place of foreign matters, such as gelfoam, hemostatic gauze and artificial implants, could reduce the possibilities of intracranial infections. Appropriate antibiotics selection,lumbar puncture catheterization and intraspinal administration of antibiotics can cure intracranial infections effectively.

A PP plastic film for food packaging (0. 1 mm) was prepared by adding two antioxidants of 2,6-di-tert-butyl-4-methyl-phenol(BHT) and pentaerythritol tetrakis ( 3-( 3, 5-di-tert-butyl-4-hydroxyphenyl ) propionate)(Irganox 1010) with different concentrations into polypropylene (PP) resin, then mixing extrusion granulate by the double screw plastic extruder and hot pressing the film at 190℃. The migration amount of the two antioxidants in food simulants (95% ethanol) was determined by high performance liquid chromatography (HPLC) with diode array detector (PDA) (detection wavelength is 282 nm). The migration of BHT was detected and Irganox 1010 was not detected. Based on the large amount of experimental data, the migration model was fitted by a software, then the migration model of antioxidant BHT was established, the applicability of the two migration model was compared with the actual data. The results showed that the fitting degree ( R2 ) of Weibull model to the actual migration result was greater than 0. 99 and better than Piringer model. It was found that there was a mathematical relationship as τ≈12. 2 ( L2/D) between parameters of Weibull model and Piringer model.

BACKGROUND: Vascular restenosis alter carotid endarteractomy (CEA) is an important factor affecting curative affect ofoperation.OBJECTIVE: To explore the role of matrix metalloproteinase-9 (MMP-9) mRNA dynamic expression in the development of early vascular restenosis after carotid endarterectomy.DESIGN, TIME AND SETTING: A random grouping contrast observation was completed in the General Hospital of Beijing Military Area Command of Chinese PLA from February 2006 to December 2007. MATERIALS: Forty-one healthy male New Zealand rabbit, weighing about 3.0 kg, with 36 ones used for preparing carotid atherosclerotic stenosis (CASS) models. experimental group, each 6 of the CASS rabbit models (n =36) were selected at the time points of hour 4, day 1, 3, 7, 30, and 90 following CEA respectively. Then they were fixed with 40 g/L polyoxymethylene perfusion and stained with hematoxylin-eosin to observe their morphologic changes.MAIN OUTCOME MEASURES: The expression changes of MMP-9 mRNA were observed dudng the development of early vascular restenosis by the quantitative real-time polymerase chain reaction technique preoperatively as well as at day 1, 3 and 7 following CEA.RESULTS: Several stages could be seen in the reparative process of neointima after CEA, including the thrombosis, the inflammatory reaction, the repair of endothelium, the proliferation of vascular smooth muscle call, the formation and accumulation of extracellular matrix. MMP-9 mRNA was expressed since day 1, reached a peak at day 3 and then decreased significantly at day 7 postoperatively.CONCLUSION: MMP-9 plays an important role in the proliferation, migration and reconstruction of vascular smooth muscle calls, the mediated reconstruction of local blood vessels, as well as the development of vascular restenosis.

Through introducing mutations into ribosomes by obtaining spontaneous drug resistance of microorganisms, ribosome engineering technology is an effective approach to develop mutant strains that overproduce secondary metabolites. In this study, ribosome engineering was used to improve the yield of butenyl-spinosyns produced by Saccharopolyspora pogona by screening streptomycin resistant mutants. The yields of butenyl-spinosyns were then analyzed and compared with the parent strain. Among the mutants, S13 displayed the greatest increase in the yield of butenyl-spinosyns, which was 1.79 fold higher than that in the parent strain. Further analysis of the metabolite profile of S13 by mass spectrometry lead to the discovery of Spinosyn α1, which was absent from the parent strain. DNA sequencing showed that there existed two point mutations in the conserved regions of rpsL gene which encodes ribosomal protein S12 in S13. The mutations occurred a C to A and a C to T transversion mutations occurred at nucleotide pair 314 and 320 respectively, which resulted in the mutations of Proline (105) to Gultamine and Alanine (107) to Valine. It also demonstrated that S13 exhibited genetic stability even after five passages.
Genetic Engineering ; Macrolides ; metabolism ; Point Mutation ; Ribosomal Proteins ; genetics ; Ribosomes ; metabolism ; Saccharopolyspora ; metabolism

Objective:To introduce a reliable and easy method of philtrum crest and philtrum repairing in secondary repair of cleft lip.Methods:Lift the upper lip flap after removing the scar on upper lip. Then the superficial orbicularis oris muscle was carefully separated, which formed the abnormal muscular eminence in the affected side after the first cleft lip repair. The pedicle of the orbicularis oris muscle the reconstructing philtrum crest. The lingual orbicularis oris muscle flap was lifted and curled from outside. The superficialorbicularis oris muscle was cut in philtrum longitudinally and turned outward. The two evertedorbicularisoris muscle flaps were sutured on both sides and fixed them on the reconstructing philtrum crest. The exposed deep orbicularis oris muscle in philtrum was sutured with the upper dermis, which formed the prominentphiltrum crest and deeper philtrum.Results:We reviewed the hospital records of patients from July 2008 to November 2021. In total, 201 patients were included in this study. All of these patients underwent the reconstruction of philtrum crest and philtrum with orbicularis oris muscle intertangling and philtrum plasty in secondary cleft lip repairing. During the treatment, the patients had no complications such as infection, hematoma and flap necrosis.198 patients were observed from 1 months to 36 months (7.8 months on average). All of them improved in different degrees in early postoperative period. Most reconstructed philtrum crest was raised and basically symmetrical with the contralateral side in shape. The philtrum was clear and the scar was not obvious. The reconstructed philtrum crest would decrease with time. 91.7% (90/98) patients were satisfied with the postoperative effects after three months.Conclusions:The method of reconstruction of philtrum crest and philtrum with orbicularis oris muscle intertangling and philtrum plasty in secondary cleft lip repairing is safe and effective. The long term postoperative effect is stable with high satisfaction as well. As a result, this method can be used as the philtrum crest and philtrum correction scheme for secondary cleft lip repairing.