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1.
Mutations in 16S rRNA that affect UGA (stop codon)-directed translation termination. 总被引:7,自引:2,他引:5 下载免费PDF全文
H U Gringer K A Hijazi E J Murgola A E Dahlberg 《Proceedings of the National Academy of Sciences of the United States of America》1991,88(15):6603-6607
Site-directed mutagenesis was performed on a sequence motif within the 3' major domain of Escherichia coli 16S rRNA shown previously to be important for peptide chain termination. Analysis of stop codon suppression by the various mutants showed an exclusive response to UGA stop signals, which was correlated directly with the continuity of one or the other of two tandem complementary UCA sequences (bases 1199-1204). Since no other structural features of the mutated ribosomes were hampered and the translation initiation and elongation events functioned properly, we propose that a direct interaction occurs between the UGA stop codon on the mRNA and the 16S rRNA UCA motif as one of the initial events of UGA-dependent peptide chain termination. These results provide evidence that base pairing between rRNA and mRNA plays a direct role in termination, as it has already been shown to do for initiation and elongation. 相似文献
2.
Device closure of ventricular septal defects. 总被引:6,自引:0,他引:6
Ziyad M Hijazi 《Catheterization and cardiovascular interventions》2003,60(1):107-114
3.
R. Lupu M. Cardillo C. Cho L. Harris M. Hijazi C. Perez K. Rosenberg D. Yang C. Tang 《Breast cancer research and treatment》1996,38(1):57-66
Summary TheerbB-2 receptor plays an important role in the prognosis of breast cancer and is expressed at high levels in nearly 30% of tumors in breast cancer patients. While evidence accumulates to support the relationship betweenerbB-2 overexpression and poor overall survival in human breast cancer, understanding of the biological consequence(s) oferbB-2 overexpression remains elusive. The discovery ofheregulin has allowed us to identify a number of related but distinct biological endpoints which appear responsive to signal transduction through theerbB-2/4 receptor. These endpoints of growth, invasiveness, and differentiation have clear implications for the emergence, maintenance, and/or control of malignancy, and represent established endpoints in the assessment of malignant progression in human breast cancer. Preliminary studiesin vitro have shown thatheregulin induces a biphasic growth effect on cells witherbB-2 overexpression. Interestingly, we observed that expression ofheregulin correlates with a more aggressive/invasive, vimentin-positive phenotype in breast cancer cells lines. Therefore, we have postulated thatheregulin is involved in breast cancer tumor progression. We have shown thatheregulin inducesin vitro chemoinvasion and chemotaxis of breast cancer cells as well as growth in an anchorage dependent and independent manner. Interestingly, aheregulin neutralizing antibody inhibits chemotaxis and results in cell growth inhibition and blockade of the invasive phenotype. Strikingly, genetically engineered cells which constitutively expressheregulin demonstrate critical phenotypic changes that are associated with a more aggressive phenotype. Specifically, these cells are no longer dependent on estrogen for growth and are resistant to tamoxifenin vitro andin vivo, and moreover these cells metastasize to lymph nodes in athymic nude mice. These tumors appear to have lostbcl-2 expression as compared with the control tumors. In addition, presumably by activation/regulation of topoisomerase II, theheregulin-transfected cells become exquisitely sensitive to doxorubicin and VP-16. Clearly, mechanistic aspects of theerbB-2/4 andheregulin interaction need to be understood from a therapeutic standpoint which could provide additional insights into synergistic treatments for certain patients, or improve treatment regimens for a large number of women. The study ofheregulin and its co-expression witherbB-2/4 receptor and the assessment of its involvement in the progression from the in situ stage of breast tumors to the invasive one will additionally increase the relevance ofheregulin as a prognostic/diagnostic factor. We believe that our studies provide new insights into breast cancer diagnosis, prognosis, and treatment.Presented at the symposium "New Approaches in the Therapy of Breast Cancer", Georgetown University Medical Center, Washington DC, October 1994, generously supported by an education grant from Bristol-Myers Squibb. 相似文献
4.
Objective: We performed this study in order to evaluate the usefulness of a new balloon expandable stent for maintaining ductal patency in a neonatal piglet model and to evaluate the ability to re-expand the stent weeks following initial implantation. Background: Maintaining patency of the ductus arteriosus without administration of Prostaglandin E has been reported previously using balloon dilation and stent implantation techniques. However, the experience is limited and the currently available stents are not modified for neonates. Methods: 14 newborn piglets all at age 12 days and median weight 3.6 Kg (range 2.7-4.3 Kg), underwent initial balloon dilation of the ductus arteriosus. Angiography after dilation demonstrated no significant left to right shunt. All piglets underwent successful stent (3.5 mm x 17 mm) placement in the ductus arteriosus. Results: Percutaneous ductal stent implantation via the arterial route was successful in all piglets with angiographic demonstration of a significant left to right shunt. Follow-up studies at weekly intervals with color flow Doppler were used to confirm patency of the stents. In 3 piglets the stent was not patent at initial follow-up and autopsy revealed sub-optimal stent placement. In two animals the stent was later re-expanded to 4 mm at 22 days, in one to 4 mm at 30 days and in one to 6 mm at 15 days, maintaining flow for an additional period of 15 to 34 days.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
5.
6.
We reviewed the long-term results of 25 patients who had localized soft tissue resections for refractory anterior retinacular knee pain. Patients completed visual analog scales to determine their activity and pain level changes, subjective assessment of their results, and whether they would have the surgery again under the same circumstances. Five of the 25 patients (20%) had had no knee surgery before the soft tissue excision, with the rest having had an average of two prior operations (range, 1 to 6). Subjectively, 22 patients (88%) noted moderate-to-substantial improvement after surgery; 3 patients (12%) declared no long-term benefit. All 25 patients stated that they would repeat the surgery under the same circumstances. Five patients (20%) noted a decrease in their results over time, but only two patients (8%) decreased their job level after surgery because of their knee pain. The average activity level dropped 60% after knee symptoms developed and increased 40% after surgery. Pain levels decreased 50% after surgery. The patients with the best overall results had lesions that were in the medial, inferomedial, or inferolateral retinaculum. The histologic results of the specimens included fibrosis, vascular proliferation, and small nerves with decreased myelin (neuromata). Our results show that specific soft tissue excision of painful tissue can often lead to successful clinical outcomes. 相似文献
7.
8.
Noa Holoshitz Damien Kenny Ziyad M Hijazi 《Methodist DeBakey Cardiovascular Journal》2014,10(2):93-98
The evolution of congenital cardiac surgery has seen significant innovative advances in collaborative efforts between congenital cardiac surgeons and interventionalists to provide the least invasive intervention with the greatest hemodynamic benefit for patients with congenital heart disease. This review looks at how this collaborative approach has evolved and is being applied to treat a number of congenital conditions across the age ranges. 相似文献
9.
Immediate and six-month results of the profile of the Amplatzer septal occluder as assessed by transesophageal echocardiography 总被引:10,自引:0,他引:10
Cao QL Du ZD Joseph A Koenig P Heitschmidt M Rhodes J Hijazi ZM 《The American journal of cardiology》2001,88(7):754-759
Catheter closure of secundum atrial septal defect (ASD) using the Amplatzer septal occluder (ASO) is a potential alternative for open surgical repair. However, the large profile of the device obtained immediately after closure continues to raise some concerns regarding its long-term safety. To evaluate the changes in the profile of the device after being deployed, transesophageal echocardiography was performed in 70 patients (17 men and 53 women) who underwent catheter closure of ASDs immediately after and at 6-month follow-up. The median age at closure was 16 years (range 1.9 to 75) and the median size of the ASD as assessed by transesophageal echocardiography was 14 mm (range 3 to 25). The thickness (profile) of the device was assessed in the 4-chamber, short- and long-axis views of the interatrial septum, and measured at its middle and at the junction of the waist with the disc at its 2 ends. Seventy-three devices were deployed in the 70 patients. The median size of the device was 19 mm (range 8 to 34). Complete closure was achieved in 81.4% and 91.4% immediately after and at 6-months follow-up, respectively. The thickness of the device at its middle decreased from 12.2 +/- 4.3, 12.2 +/- 3.7, and 12.5 +/- 4.3 mm in the 4-chamber, short- and long-axis views to 6.5 +/- 2.0, 6.3 +/- 1.9, and 6.5 +/- 2.2 mm, respectively. The thickness of the device at its superior, inferior, anterior, and posterior edges also decreased by 41.8% +/- 14.0% to 43.7% +/- 9.8%. The changes in the thickness were related to device size. Larger devices were thicker after being deployed. We conclude that the thickness of the ASO decreases by 42% to 48% within 6 months after deployment, resulting in a lower profile. 相似文献
10.
Zahid Amin MD FSCAI Ziyad M. Hijazi MD FSCAI John L. Bass MD John P. Cheatham MD FSCAI William Hellenbrand MD FSCAI Charles S. Kleinman MD FSCAI 《Catheterization and cardiovascular interventions》2008,72(1):74-79
Objectives: To evaluate all complications that occurred during or after cardiac catheterizations for Amplatzer PFO device closure of patent foramen ovale (PFO), determine the cause of the complications and recommend techniques to minimize complications in the future. Background: Rare complications were reported to the manufacturer of the Amplatzer PFO occluder since the introduction of the device. Methods: A panel of independent physicians reviewed all complications reported to the manufacturer to determine whether the complication was related to the device or related to the cardiac catheterization procedure. Demographic data, echocardiograms, operative reports, and time to occurrence of complications were reviewed. Results: A total of 11 events were reported. Only two patients had device related complications (erosion), an incidence of 0.018%. Two patients were found to have additional atrial septal defect after PFO closure. Two patients were thought to have an inflammatory reaction without any serious sequelae. Five complications were related to the cardiac catheterization procedure (atrial appendage perforation). Conclusions: Device related complications after Amplatzer PFO occluder placement are extremely rare. Cardiac catheterization related complications appear to be the most common cause of the hemodynamic compromise. Careful manipulation of catheters and wires, recognition of the location of the catheter by fluoroscopy and echocardiography will decrease the risk of such complications. © 2008 Wiley‐Liss, Inc. 相似文献