ABSTRACT
Objective To verify the feasibility of using small intestine submucosa for graft stents.Methods A Z-type Nitinol wire stent was used as the metal stent material,and porcine small intestine submucosa was used as the biofilm material to prepare the bio-coated stent.In vitro implantation,extracorporeal pulsation and extracorporeal flexion of the stents were designed based on the requirements for the small intestine submucosa graft stent implantation during the endovascular aneurysm repair and of the mechanical properties of the graft stent during human body activity.The feasibility of using small intestine submucosa for the graft stents was evaluated according to the patency of the stent lumen after the experiment,the presence or absence of cracks in the membrane,and the presence or absence of fracture of the metal stent.Results In the in vitro experiments,all the samples were able to maintain complete tunica and luminal patency except the 8th sample that showed suture rupture.Besides,all the samples showed good rebounding and adhering properties in both in vitro implantations and extracorporeal pulsation pressure experiments,and no dangerous problems were found such as film rupture,suture loss and stent fracture.Conclusion Small intestine submucosa can meet the durability requirements of graft stents,adapt to the conditions of graft stents such as implantation,bending and blood pulsation,and can be used as the covering material of graft stents.
ABSTRACT
Objective To evaluate the role of calcium channel in the mechanism of the generation and maintenance of bursting firing of substantia nigra pars compacta (SNc) dopaminergic neurons in rats.Methods Using the patch clamp technique,we observed the firing pattern switching features after adding 10 μmol/L N-methyl-D-aspartic acid (NMDA),compared the changes of whole-calcium current and L-type calcium current with or without NMDA,and analyzed the correlation between the generation of burst firing and L-type calcium channel activation.Results After NMDA treatment,the firing pattern of SNc dopaminergic neurons changed to burst firing,which was compromised by a charastistic high plateau potential and series of action potential on it.The current density of L-type calcium current increased significantly after adding NMDA,which,from (2.86 ±0.26) pA/pF (n =28),significantly increased to (3.75 ± 0.18) pA/pF (n =34 ; t =7.52,P =0.002 8).The high plateau potential was almost abolished with the application of verapamil,a specific antagonist of L-type calcium channel.Consiusion NMDA could induce the firing pattern changed to burst firing in SNc dopaminergic neurons,while L-type calcium channel contributes to the process of generation and maintenance of burst firing.
ABSTRACT
OBJECTIVE To investigate the prevalence of erythromycin resistance genes ermB and mefA and the relationship of drug resistance and genes in Streptococcus pneumoniae.METHODS Forty three strains of S. pneumoniae were collected from respiratory system infected children from Dec 2004 to Oct 2005 at Yuying Pediatric Hospital of Wenzhou Medical College.Erythromycin sensitivity test was done by using MIC method.The erythromycin resistance genes ermB and mefA were detected by PCR.RESULTS In all forty three strains,forty were erythromycin resistant(93%),three were erythromycin sensitive.The total detection rate of erythromycin resistance genes ermB and mefA was 76.7% and 23.3%,respectively.There were neither gene ermB nor gene mefA in 3 erythromycin-sensitive S.pneumoniae.In 40 strains the detection rate of gene ermB was 82.5% and that of gene mefA was 25%.The erythromycin resistance gene ermB or mefA were detected in 35 of the 43 strains.The total detection rate of erythromycin resistance gene was 81.4%.In the 35 erythromycin resistance strains there were 25 strains in which gene ermB existed lonely and 2 strains in which gene mefA existed lonely.There were both genes ermB and gene mefA in 8 of the 35 erythromycin resistance strains.CONCLUSIONS The erythromycin resistance of S.pneumoniae can be caused mainly by gene expression of ermB or mefA,but the gene mefA seems to be less important than gene ermB.Obviously the erythromycin isn′t useful in treating S.pneumoniae infection.