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排序方式: 共有962条查询结果,搜索用时 15 毫秒
81.
JE Manning DN Batson TW Gansman CA Murphy SG Perretta EA Norfleet 《Canadian Metallurgical Quarterly》1997,4(9):883-890
With the aim of developing foetal gene therapy for cystic fibrosis, we have investigated the possibility of gene targeting to the mouse foetus with two different viral vector systems and at different times of gestation. We report here that recombinant retrovirus producing cells administered into the intra-amniotic cavity of mid- to late-gestation mouse MF1 foetuses survive in the amniotic fluid and are able to engraft to a certain extent in foetal tissues. By production of infectious virus they mediate transduction and beta-galactosidase transgene expression in neighbouring foetal tissues 24 to 72 h following injection. Retrovirus producer cells could, therefore, become a means to overcome the limitations of low retroviral titre, for in vivo foetal gene transfer. To investigate the developmental stage at which transduction of the airways and enteral systems can be obtained we also administered a highly infective first generation adenoviral vector (AdRSV beta gal) into the amniotic cavity of foetal mice between 13 to 16 days post coitus, beta-galactosidase activity was detected between 24 to 120 h after injection. The highest levels of transgene expression were generally observed between 48 to 72 h following injection of the adenoviral vector. We demonstrate that infection of the pulmonary airways is dependent on the developmental stage of the foetus and can be achieved on the 15th day of gestation. 相似文献
82.
Immunization by peptides based on the repeat sequences of Plasmodium falciparum or P. vivax antigen(s) have shown inconsistent results during clinical trials in humans. This could be attributed to the lack of T-cell help or antigenic polymorphism. Thus, attention has been focused towards the more conserved non-repeat regions. The present study was undertaken to map the antigenic determinant in the vicinity of region II (outside the repeat) of CS protein of P. vivax. The immunogenicity of the peptide was studied alone and after linking with polytuftsin (PT), using alum and Freund's adjuvant, in inbred strains of mice with different genetic backgrounds. The humoral response and antigen induced T-cell proliferation assays clearly demonstrated the immunomodulatory activity of PT. Comparable results were observed with antigen(s) administered either in alum or Freund's adjuvant. The induction of IgG2a and IgG2b antibody isotypes by both, peptide as well as the conjugate, may indicate that the T-helper response involved is of Th1 type. Further the immunofluorescence studies have shown that antibodies recognized the air dried sporozoites of P. cynomolgi. The results thus show that the above sequence has overlapping B and T-cell determinants and that alum can be substituted for Freund's adjuvant in generating an effective immune response. 相似文献
83.
Computational coupling of moisture diffusion and mechanical deformation in polymer matrix composites
M. Bailakanavar J. Fish V. Aitharaju W. Rodgers 《International journal for numerical methods in engineering》2014,98(12):859-880
A computationally efficient multiscale–multiphysics model aimed at predicting mechanical response of thermoplastic composites subjected to different levels of moisture was developed. The mathematical model of the coupled moisture‐diffusion–mechanical‐deformation phenomenon was stated at the microscale, based on the observed experimental data, and then upscaled using a mathematical homogenization approach. A two‐way coupling between moisture diffusion and mechanical deformation was introduced by which diffusivity was enhanced by hydrostatic strain, whereas strength and stiffness were assumed to degrade because of moisture ingression, which also gives rise to swelling. The computational complexity of analyzing the two coupled physical processes at multiple scales was reduced via a model reduction scheme for multiple physical processes. The model was validated for 30% by weight filled glass fiber and carbon fiber reinforced thermoplastic composites. The moisture conditioning and uniaxial tension experiments were utilized to identify diffusion and mechanical properties at a fine scale. The identified properties were then used to validate the formulation in the three‐point bending test. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
84.
W. Fish J. D. Key E. Mwambene 《Applicable Algebra in Engineering, Communication and Computing》2014,25(5):363-382
We examine the ternary codes \(C_3(A_i+I)\) from matrices \(A_i+I\) where \(A_i\) is an adjacency matrix of a uniform subset graph \(\Gamma (n,3,i)\) of \(3\) -subsets of a set of size \(n\) with adjacency defined by subsets meeting in \(i\) elements of \(\Omega \) , where \(0 \le i \le 2\) . Most of the main parameters are obtained; the hulls, the duals, and other subcodes of the \(C_3(A_i+I)\) are also examined. 相似文献
85.
DI Rodenhiser JD Andrews DN Mancini JH Jung SM Singh 《Canadian Metallurgical Quarterly》1997,373(2):185-195
Glutamatergic synaptic potentials induced by micromolar concentrations of the potassium conductance blocker 4-aminopyridine (4-AP) were recorded intracellularly from rat neostriatal neurons in the presence of 10 microM bicuculline (BIC). These synaptic potentials originate from neostriatal cortical and thalamic afferents and were completely blocked by 10 microM 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) plus 100 microM D-2-amino-5-phosphonovaleric acid (2-APV). Their inter-event time intervals could be fitted to exponential distributions, suggesting that they are induced randomly. Their amplitude distributions had most counts around 1 mV and fewer counts with values up to 5 mV. Since input resistance of the recorded neurons is about 40 M omega, the amplitudes agree to quantal size measurements in mammalian central neurons. The action of a D2 agonist, quinpirole, was studied on the frequency of these events. Mean amplitude of synaptic potentials was preserved in the presence of 2-10 microM quinpirole, but the frequency of 4-AP-induced glutamatergic synaptic potentials was reduced in 35% of cases. The effect was blocked by the D2 antagonist sulpiride (10 microM). Input resistance, membrane potential, or firing threshold did not change during quinpirole effect, suggesting a presynaptic site of action for quinpirole in some but not all glutamatergic afferents that make contact on a single cell. The present experiments show that dopaminergic presynaptic modulation of glutamatergic transmission in the neostriatum does not affect all stimulated afferents, suggesting that it is selective towards some of them. This may control the quality and quantity of afferent flow upon neostriatal neurons. 相似文献
86.
DN Angelov M Walther M Streppel O Guntinas-Lichius AM van Dam E Stennert WF Neiss 《Canadian Metallurgical Quarterly》1998,54(6):820-827
An adeno-associated virus (AAV) vector, expressing genes for human tyrosine hydroxylase (TH) and aromatic amino acid decarboxylase (AADC), demonstrated significantly increased production of dopamine in 293 (human embryonic kidney) cells. This bicistronic vector was used to transduce striatal cells of six asymptomatic but dopamine-depleted monkeys which had been treated with the neurotoxin MPTP. Striatal cells were immunoreactive for the vector-encoded TH after stereotactic injection for periods up to 134 days, with biochemical effects consistent with dopamine biosynthetic enzyme expression. A subsequent experiment was carried out in six more severely depleted and parkinsonian monkeys. Several TH/aadc-treated monkeys showed elevated levels of dopamine near injection tracts after 2.5 months. Two monkeys that received a beta-galactosidase expressing vector showed no change in striatal dopamine. Behavioral changes could not be statistically related to the vector treatment groups. Toxicity was limited to transient fever in several animals and severe hyperactivity in one animal in the first days after injection with no associated histological evidence of inflammation. This study shows the successful transfection of primate neurons over a period up to 2.5 months with suggestive evidence of biochemical phenotypic effects and without significant toxicity. While supporting the idea of an in vivo gene therapy for Parkinson's disease, more consistent and longer lasting biochemical and behavioral effects will be necessary to establish the feasibility of this appraoch in a primate model of parkinsonism. 相似文献
87.
E Roine DM Raineri M Romantschuk M Wilson DN Nunn 《Canadian Metallurgical Quarterly》1998,11(11):1048-1056
Many strains of Pseudomonas syringae produce retractile pili that act as receptors for lytic bacteriophage phi 6. As these are also characteristics of type IV pili, it was postulated that P. syringae may possess genes for type IV pilus biogenesis. A cosmid clone bank of P. syringae pv. tomato DC3000 genomic DNA was used to complement a mutant of Pseudomonas aeruginosa defective in the PilD (XcpA) prepilin peptidase gene by selection for restoration of extracellular protein secretion, a function also known to require PilD. A cosmid able to complement this mutant was also able to complement mutations in the pilB and pilC genes, suggesting that, if the organization of these genes is similar to that of P. aeruginosa, the cosmid may contain the P. syringae pilA. This was confirmed by sequencing a region from this plasmid that was shown to hybridize at low stringency to the P. aeruginosa pilA gene. The deduced P. syringae PilA polypeptide possesses the characteristic properties of the type IV pilins. Heterologous expression of the P. syringae pilA in P. aeruginosa was also shown, conferring not only phi 6 phage sensitivity to P. aeruginosa pilA mutants but also sensitivity to PO4, a lytic bacteriophage specific for the pilus of P. aeruginosa. This suggests that additional components might be present in the mature pilus of P. aeruginosa that are the true receptors for this phage. Chromosomal mutations in P. syringae pv. tomato DC3000 pilA and pilD genes were shown to abolish its sensitivity to bacteriophage phi 6. To determine the importance of P. syringae pilus in plant leaf interactions, these mutations were tested under laboratory and field conditions. Although little effect was seen on pathogenicity, culturable leaf-associated population sizes of the pilA mutant were significantly different from those of the wild-type parent. In addition, the expression of the DC3000 pilA gene appears to contribute to the UV tolerance of P. syringae and may play a role in survival on the plant leaf surface. 相似文献
88.
JW Ramsdell L Fish D Graft N Higgins M Kavuru W Pleskow D Banerji 《Canadian Metallurgical Quarterly》1998,80(5):385-390
The objectives of this work was to (1) study the bone mineral density (BMD) of the lumbar spine, total skeleton, and body composition in patients with primary biliary cirrhosis (PBC) and (2) evaluate the risk factors (premature menopause, stages of the disease, hyperbilirubinemia) and bone and liver biochemical parameters for the development of osteoporosis. We studied 23 women with a compatible diagnosis of PBC. The BMD and body composition were evaluated by X-ray absorptiometry (Lunar DPX-L). The average age of the population was 56.7 +/- 10.2 years. The BMD of the lumbar spine and of the total skeleton was 1.3 SDs below the normal population matched for sex and age. In the total skeleton, the legs were the most severely affected area (Z score -1.5). The body composition showed no significant difference compared with the normal population. The BMD of 56% of the patients was less than -2.5 SDs from the average normal young values. Patients with a history of vertebral fractures had diminished mineral density of the lumbar spine, as did those who had had no fractures. Of the risk factors studied, patients with premature menopause had a lower bone mass compared with patients with normal menopausal age (Z score of the total skeleton was -2.1 +/- 1.8 versus -1.1 +/- 1.0) but the difference did not reach statistical significance. The bone mass was not affected in patients with regular menstrual cycles. There were no statistically significant differences in high levels of bilirubin, advanced stages of the disease, or the biochemical variables studied. It is concluded that patients with primary biliary cirrhosis present diminished cortical and trabecular bone mass, whereas body composition was unaffected. Premature hormone deficit, possibly triggered by the chronic hepatic pathology, is a contributing factor to the osteoporosis in this population. 相似文献
89.
RP Mlcak MH Desai E Robinson RL McCauley J Richardson DN Herndon 《Canadian Metallurgical Quarterly》1995,21(5):337-339
During a transjugular intrahepatic portosystemic shunt (TIPS) procedure, a Strecker stent was accidently pushed into the superior mesenteric vein. After successful shunt placement, the stent was withdrawn into the hepatic vein. A multipurpose basket catheter was attached to the distal end of the stent and a loop snare to the proximal end. In this way it was possible to stretch the stent and retrieve it percutaneously through the jugular sheath. 相似文献
90.
SM Palmer NG Henshaw DN Howell SE Miller RD Davis VF Tapson 《Canadian Metallurgical Quarterly》1998,113(4):944-950
STUDY OBJECTIVE: To define the epidemiology, clinical manifestations, and long-term complications of respiratory viral infections in adult lung transplant recipients. DESIGN: Retrospective review of the records of 122 adult lung transplant recipients over a 5-year period at one institution. RESULTS: Ten episodes of infection with respiratory syncytial virus, parainfluenza, influenza, or adenovirus were identified. All patients presented with symptoms of respiratory tract infection. Two patients died acutely and four patients subsequently had development of obliterative bronchiolitis (OB). CONCLUSIONS: These data suggest community respiratory viral infections cause significant morbidity and mortality in lung transplant recipients. Further prospective studies are warranted to clarify the relationship between respiratory viral infection and OB and to define the optimal therapy for these viral infections. 相似文献