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1.
Catheter Cardiovasc Interv ; 91(2): 322-329, 2018 02 01.
Article in English | MEDLINE | ID: mdl-28303634

ABSTRACT

OBJECTIVES: This report demonstrates the application and feasibility of novel 3D-MDCT real-time fusion technology with fluoroscopy, for left atrial appendage (LAA) occlusion procedures. BACKGROUND: A successful LAA occlusion procedure relies on multiple imaging modalities, including TEE or 3D-MDCT, and fluoroscopy. Effectively integrating these imaging modalities may improve implantation safety and success. To our knowledge this technique has not been previously described for LAA occlusions. METHODS: This observational study compared clinical and procedural parameters for procedures performed with or without fusion integration. All patients had a pre-procedural 3D-MDCT for LAA measurements, along with 3D analyses of LAA morphology and surrounding structures. Using the image fusion software (Valve ASSIST 2, GE Healthcare, UK), landmarks were identified on fluoroscopy, and MDCT LAA anatomy outlines were then projected onto the real-time fluoroscopy image during the procedure, to guide all steps of the intervention. RESULTS: A total of 57 patients underwent LAA occlusion, with 16 performed using fusion software. In comparison to the pre-fusion group, reductions in contrast volume (21.0 ± 11.7 vs. 95.9 ± 80.5 ml, P < 0.001), procedure time (63.0 ± 22.0 vs. 87.3 ± 43.0 min, P = 0.01), and fluoroscopy time (6.2 vs. 8.3 min, P = 0.03) were observed. Incomplete sealing (0 vs. 14.6%, P = 0.16) and device deployment success (100 vs. 92.7%, P = 0.17) were not significantly different. CONCLUSIONS: The addition of this novel fusion technology is safe and feasible. To optimize LAA procedural success, fusion integration may offer a promising addition, or alternative, to current imaging modalities. © 2017 Wiley Periodicals, Inc.


Subject(s)
Atrial Appendage/diagnostic imaging , Atrial Fibrillation/diagnostic imaging , Atrial Fibrillation/therapy , Cardiac Catheterization , Imaging, Three-Dimensional/methods , Multidetector Computed Tomography/methods , Radiographic Image Interpretation, Computer-Assisted/methods , Radiography, Interventional/methods , Aged , Aged, 80 and over , Anatomic Landmarks , Atrial Appendage/physiopathology , Atrial Fibrillation/physiopathology , Cardiac Catheterization/instrumentation , Feasibility Studies , Female , Fluoroscopy , Humans , Male , Multimodal Imaging , Predictive Value of Tests , Retrospective Studies , Treatment Outcome
2.
Allergy ; 65(5): 636-44, 2010 May.
Article in English | MEDLINE | ID: mdl-19845572

ABSTRACT

BACKGROUND: Exhaled NO can be partitioned in its bronchial and alveolar sources, and the latter may increase in the presence of recent asthmatic symptoms and in refractory asthma. The aim of this multicentre prospective study was to assess whether alveolar NO fraction and FE(NO) could be associated with the level of asthma control and severity both at the time of measurement and in the subsequent 3 months. METHODS: Asthma patients older than 10 years, nonsmokers, without recent exacerbation and under regular treatment, underwent exhaled NO measurement at multiple constant flows allowing its partition in alveolar (with correction for back-diffusion) and bronchial origins based on a two-compartment model of NO exchange; exhaled NO fraction at 50 ml/s (FE(NO,0.05)) was also recorded. On inclusion, severity was assessed using the four Global initiative for asthma (GINA) classes and control using Asthma Control Questionnaire (ACQ). Participants were followed-up for 12 weeks, control being assessed by short-ACQ on 1st, 4th, 8th and 12th week. RESULTS: Two-hundred patients [107 children and 93 adults, median age (25th; 75th percentile) 16 years (12; 38)], 165 receiving inhaled corticosteroid, were included in five centres. The two-compartment model was valid in 175/200 patients (87.5%). Alveolar NO and FE(NO,0.05) did not correlate to control on inclusion or follow-up (either with ACQ /short-ACQ values or their changes), nor was influenced by severity classes. Alveolar NO negatively correlated to MEF(25-75%) (rho = -0.22, P < 0.01). CONCLUSION: Alveolar and exhaled NO fractions are not indexes of control or severity in asthmatic children and adults under treatment.


Subject(s)
Asthma/diagnosis , Nitric Oxide/analysis , Adolescent , Adrenal Cortex Hormones/therapeutic use , Adult , Anti-Asthmatic Agents/therapeutic use , Asthma/drug therapy , Breath Tests/methods , Child , Exhalation , Female , Humans , Male , Middle Aged , Pulmonary Alveoli/metabolism , Young Adult
3.
Minerva Cardioangiol ; 58(5): 599-610, 2010 Oct.
Article in English | MEDLINE | ID: mdl-20948506

ABSTRACT

Drug eluting stents (DES) have changed the landscape of interventional cardiology with their high efficacy in preventing restenosis. Several DES are available for clinical use with different drugs, polymers and platforms. The Nobori™ is a novel generation drug eluting stent. The drug, Biolimus A9™, a sirolimus analogue, is immersed in a biodegradable polymer which is applied solely to the abluminal surface of a flexible stainless steel stent platform. The drug-polymer matrix is designed to release the drug simultaneously with the polymer degradation in a process lasting between 6-9 months. The coating design along with the lipophilicity of the drug is expected to optimize drug distribution and to reduce its release into the peripheral circulation. The drug free luminal surface might reduce negative impact on endothelization observed with DES with circumferential coating and durable polymers. Nobori™ stent is extensively studied in the comprehensive NOBORI clinical program. This stent showed superiority versus Taxus Liberte stent for in-stent late loss at 9 months in NOBORI 1 study, similarity to Cypher stent in NOBORI CORE study and superior performance versus both Taxus and Cypher stent in the study indirectly assessing endothelial function at 6-9 months after stent implantation. The landmark of NOBORI trials is very low rate of late and very late stent thrombosis along with exceptionally low target lesion revascularization rate.


Subject(s)
Coronary Restenosis/prevention & control , Drug-Eluting Stents , Clinical Trials as Topic , Equipment Design , Follow-Up Studies , Humans , Lactic Acid , Polyesters , Polymers , Randomized Controlled Trials as Topic
4.
J Phys Condens Matter ; 21(30): 305601, 2009 Jul 29.
Article in English | MEDLINE | ID: mdl-21828554

ABSTRACT

The magnetic properties of the antiferromagnet CeNiSnH and of the ferromagnet CeNiSnH(1.8) on hydrostatic pressure (0≤P≤10.8 bar) have been determined using a miniature piston-cylinder CuBe pressure cell. With increasing P, the Néel temperature of CeNiSnH increases weakly from 4.77 to 5.01 K whereas the Curie temperature of CeNiSnH(1.8) decreases rapidly from 7.16 to 5.30 K. Similar pressure dependence is also observed in the critical field of the metamagnetic transition of CeNiSnH and in the coercive field of CeNiSnH(1.8). Electronic structure calculations for these hydrides within the density functional theory show agreement with the experimental findings. Detailed examination of the chemical bonding features point to the conclusion that the antibonding Ce-Ni states below the Fermi level for CeNiSnH(1.8) could be responsible for the decrease of its Curie temperature under applied pressure.

5.
Ann Biol Clin (Paris) ; 67(2): 219-23, 2009.
Article in French | MEDLINE | ID: mdl-19297295

ABSTRACT

UNLABELLED: Asymptomatic urinary tract infections are common in diabetic patients. The aim of this 10 months prospective study is to evaluate urinary dipstick tests versus cytobacteriological examination to conclude the absence of urinary tract infection in diabetic subjects. Each diabetic patient hospitalised for less than 8 hours and for whom it was decided a cytobacteriological examination was included in the study (141 samples). At the same time (and at patient's bedside) a dipstick urinalisys (glucose, leucocytes, nitrite, blood, protein, and ketone) was carried out. Sensitivity, specificity, negative predictive value, post test probability and negative likehood ratio were calculated. RESULTS: the combination of leucocyte zone with nitrite zone (both negative) has a 85,2% sensitivity, avoids 65% of cytobacteriology, but has an odd ratio at 0,20. Those results are improved when the glucose zone (negative test or less than 4 crosses) is taken into account, with a 96,3% sensitivity, 63,4% cytobacteriology avoided and a negative likehood ratio at 0,06. CONCLUSION: The addition of the glucose test to the usual leucocytes and nitrite tests seems to allow one to conclude the absence of urinary tract infection in diabetic patients; this is worth studying with a more extensive sample.


Subject(s)
Diabetic Nephropathies/urine , Reagent Strips , Urinary Tract Infections/diagnosis , Algorithms , Bacterial Infections/diagnosis , Bacterial Infections/urine , Diabetic Nephropathies/diagnosis , Glycosuria/diagnosis , Humans , Likelihood Functions , Probability , Proteinuria/diagnosis , Sensitivity and Specificity
6.
Med Trop (Mars) ; 69(5): 506-8, 2009 Oct.
Article in French | MEDLINE | ID: mdl-20025186

ABSTRACT

Nocardiosis is a rare disease that is difficult to diagnose. Pulmonary forms are most common in association with a variety of nonspecific symptoms. Up to now isolation of the offending species, i.e., Nocardia aroensis, has been reported only once during the first description in Japan. The purpose of this article is to report the second world case of isolation of the Nocardia aroensis in a 50-year-old immunocompetent African woman.


Subject(s)
Lung/microbiology , Nocardia Infections/diagnosis , Anti-Bacterial Agents/therapeutic use , Female , Humans , Immunocompetence , Middle Aged , Nocardia/genetics , Nocardia/isolation & purification , Nocardia Infections/drug therapy , Polymerase Chain Reaction , Senegal
7.
Rev Pneumol Clin ; 65(1): 13-5, 2009 Feb.
Article in French | MEDLINE | ID: mdl-19306778

ABSTRACT

Tuberculous spondylitis is the most common form of musculoskeletal tuberculosis. However, extraspinal manifestations have been described with tuberculosis of the wrist, femur, foot or shoulder, as in the patient presented. Because of an often-indolent clinical presentation, the diagnosis is delayed and antituberculous treatment is not able to prevent serious bone destruction.


Subject(s)
Shoulder Pain/etiology , Tuberculosis, Osteoarticular/diagnosis , Adult , Antitubercular Agents/therapeutic use , Female , Humans , Senegal , Tuberculosis, Osteoarticular/drug therapy
8.
Ann Cardiol Angeiol (Paris) ; 68(6): 429-433, 2019 Dec.
Article in French | MEDLINE | ID: mdl-31668338

ABSTRACT

The population of elderly patients comprises a high percentage of women. This population is more vulnerable due to the presence of numerous comorbidities and is, therefore, particularly exposed to the risk of aortic valve degeneration, resulting in aortic valve stenosis whose symptoms are predictors of poor short-term outcomes. In the presence of symptomatic aortic stenosis, the recommended therapeutic option in this vulnerable population is the implementation of transcatheter aortic valve implantation, preferably via the femoral route. The outcomes of this procedure are better in women than in men despite a more frequent occurrence of vascular, bleeding and cerebral complications. Several hypotheses have been reported in the literature regarding the reasons for such differences. Among other reasons, it is likely that in female patients, the myocardium adjusts better to the occurrence of aortic stenosis and that recovery after valve treatment is also more optimal. Another explanation is the higher frequency of coronary artery disease in this older population. This has a considerable impact on the outcome even when coronary lesions are treated prior to valve implantation. There is still room for improvement and progress can be achieved by further reducing the size of the equipment used in order to decrease the diameter of the vascular access, and by continuing to simplify TAVI procedures. Less invasive techniques should result in decreased complication rates. In addition, dedicated studies should allow us to further improve our practice in this growing population of vulnerable patients.


Subject(s)
Aortic Valve Stenosis/surgery , Transcatheter Aortic Valve Replacement , Adaptation, Physiological , Aged , Aortic Valve Stenosis/etiology , Coronary Artery Disease/epidemiology , Coronary Artery Disease/therapy , Equipment Design , Female , Femoral Artery , Humans , Pregnancy , Prognosis , Sex Factors , Transcatheter Aortic Valve Replacement/adverse effects , Treatment Outcome
9.
Med Trop (Mars) ; 68(6): 593-6, 2008 Dec.
Article in French | MEDLINE | ID: mdl-19639825

ABSTRACT

Nosocomial Infection (NI) is also observed in healthcare facilities in non-Western countries. The purpose of this report is to describe the findings of a survey undertaken to evaluate hygiene procedures implemented at the "Hopital Principal" in Dakar, Senegal and to assess perception and awareness of nosocomial risk among the hospital staff. A total of 264 healthcare workers were interviewed. Mean age was 39 years (range, 18-60) and the sex ratio was 1.3 (150 men/114 women). Sixty (22.7%) had university degrees, 106 (40.2%) had secondary school diplomas, 50 (18.9%) had attended middle school, and 13 (4.9%) had no schooling. Analysis of interview data showed that 56.1% (157/264) defined NI as infection acquired at the hospital but that only 9.8% (n=26) knew that a minimum 48-hour delay was necessary to distinguish nosocomial from community acquired infection. While understanding about NI was correlated with education level, data showed that 1 out of 3 physicians (13/39) failed to give the exact definition. Hand contact was cited as the second route of transmission. Isolation precautions were understood by 22.7% of personnel (60/264). Systematic handwashing was reported by 363% (96/264) but observation demonstrated that it was not performed properly regardless of the category of personnel. Care protocols were understood by 54.6% of persons interviewed (144/264). A hygiene-training course had been attended by 52.2% (n=138). Two thirds of the staff (69.7%: 54/264) was able to identify the hygiene nurse. Ninety-eight health care providers (37.1%) were familiar with the CLIN (Comités de Lutte contre les Infections Nosocomiales).


Subject(s)
Clinical Competence , Cross Infection/prevention & control , Health Knowledge, Attitudes, Practice , Infection Control , Adolescent , Adult , Female , Humans , Male , Middle Aged , Personnel, Hospital , Risk , Senegal
10.
Ann Cardiol Angeiol (Paris) ; 67(6): 455-465, 2018 Dec.
Article in English | MEDLINE | ID: mdl-30376969

ABSTRACT

Aortic stenosis is a frequent disease in the elderly. Its prevalence is 0.4% with a sharp increase after the age of 65, and its outcome is very poor when the patient becomes symptomatic. The interventional procedure known as TAVI (trans-catheter aortic valve implantation), which was developed in France and carried out for the first time in Rouen by Prof. Alain Cribier and his team in 2002, has proven to be a valid alternative to surgical aortic valve replacement. At first, this technique was shown to be efficient in patients with contra-indications to surgical treatment or deemed to be at high surgical risk. Given the very promising outcomes achieved as a result of close heart team collaboration, appropriate patient selection, simplified procedures and reduced complication rates, transfemoral (TF) TAVI is now preferred in symptomatic intermediate risk patients>75 years old according to the latest ESC guidelines. In 2017, in France, TAVI is currently performed in 50 centers with on-site cardiac surgery. The 2016 TAVI outcomes recorded in the French national TAVI registry (France TAVI) are very encouraging and show that for 7133 patients treated (age 83.4±7 years, logistic Euroscore 14%), 87% of whom via the TF approach, cross-over to surgery was very low (0.5%) with a 3.0% in-hospital mortality rate. The substantial increase in TAVI indications and the improvement of its outcomes may in the near future call for a reconsideration of the number of high volume centers authorized to carry out this technique.


Subject(s)
Aortic Valve Stenosis/surgery , Transcatheter Aortic Valve Replacement , Anticoagulants/therapeutic use , Aortic Valve Stenosis/diagnostic imaging , Aortic Valve Stenosis/epidemiology , Atrial Fibrillation/drug therapy , Atrial Fibrillation/epidemiology , Diagnostic Imaging , France/epidemiology , Heart Valve Prosthesis , Hospital Mortality , Humans , Patient Selection , Transcatheter Aortic Valve Replacement/adverse effects
11.
Rev Pneumol Clin ; 63(4): 247-50, 2007 Sep.
Article in French | MEDLINE | ID: mdl-17978735

ABSTRACT

AIM: Pleural biopsy and adenosine deaminase activity are not available at our center and the treatment begins without substantiation diagnosis in patients with tuberculous pleural effusion (PE). METHODS: In order to evaluate the validity of an empiric antituberculous therapy in exsudative PE with high prevalence of lymphocytes, we conducted a retrospective study during 1 year. Patient was enrolled if no signs of tuberculous infection, pneumonia or cancer were present. RESULTS: During 1 year, 38 patients were enrolled (23 males, mean age=36 years). PE was major (> 2/3 of the lung) in 14 cases, moderate (between 1/3 and 2/3) In 18 cases and minor (<1/3) in 6 cases. Tuberculous contagion was observed in 10 patients. Tuberculinic test was positive in all patients (12-24 mm). Clinical and radiological cure was obtained in 37 cases, except 1 patient who died from acute heart failure. No recurrence of PE was observed after 1 year follow-up. CONCLUSION: In our endemic areas, empiric antituberculous treatment seems to be an effective strategy in patients with exsudative PE.


Subject(s)
Antitubercular Agents/therapeutic use , Pleural Effusion/drug therapy , Tuberculosis, Pleural/drug therapy , Adult , Cause of Death , Female , Follow-Up Studies , Heart Failure/physiopathology , Humans , Lymphocytosis/pathology , Male , Pleural Effusion/pathology , Retrospective Studies , Senegal , Treatment Outcome , Tuberculin Test , Tuberculosis, Pleural/diagnosis
12.
J Phys Condens Matter ; 18(26): 6045-56, 2006 Jul 05.
Article in English | MEDLINE | ID: mdl-21690817

ABSTRACT

The hydrides CeCoSiH(1.0) and CeCoGeH(1.0) which crystallize like the parent antiferromagnetic compounds CeCoSi and CeCoGe in the tetragonal CeFeSi-type structure, have been investigated by specific heat and thermoelectric power measurements and (1)H nuclear magnetic resonance (NMR). CeCoSiH(1.0) is an intermediate valence compound whereas CeCoGeH(1.0) can be considered as a nearly trivalent cerium compound. This behaviour is corroborated by the occurrence of a slight broadening of the (1)H NMR signal in the sequence [Formula: see text]. The band structure calculations performed on these hydrides reveal the existence of strong bonding Ce-H interaction, found to be larger in CeCoSiH(1.0) than in CeCoGeH(1.0).

13.
Nucleic Acids Res ; 29(18): 3757-74, 2001 Sep 15.
Article in English | MEDLINE | ID: mdl-11557808

ABSTRACT

Homing endonucleases confer mobility to their host intervening sequence, either an intron or intein, by catalyzing a highly specific double-strand break in a cognate allele lacking the intervening sequence. These proteins are characterized by their ability to bind long DNA target sites (14-40 bp) and their tolerance of minor sequence changes in these sites. A wealth of biochemical and structural data has been generated for these enzymes over the past few years. Herein we review our current understanding of homing endonucleases, including their diversity and evolution, DNA-binding and catalytic mechanisms, and attempts to engineer them to bind novel DNA substrates.


Subject(s)
Endodeoxyribonucleases/metabolism , Alternative Splicing/genetics , Amino Acid Sequence , Base Sequence , Binding Sites/genetics , Catalysis , DNA/chemistry , DNA/genetics , DNA/metabolism , Endodeoxyribonucleases/chemistry , Endodeoxyribonucleases/genetics , Evolution, Molecular , Introns/genetics , Molecular Sequence Data , Nucleic Acid Conformation , Protein Conformation , Protein Splicing/genetics , Sequence Homology, Amino Acid
14.
Arch Mal Coeur Vaiss ; 99 Spec No 1(1): 57-60, 2006 Jan.
Article in French | MEDLINE | ID: mdl-16479965

ABSTRACT

During 2005, the evolution of interventional cardiology has largely been dominated by the trial of active endoprostheses, whose advantage has been consistently shown by various studies, mete-analyses and surveys. Extending their use to new indications and evaluating new drugs have also been studied. In parallel, clinical trials have been performed in the promising field of percutaneous treatment of valvular heart disease, particularly mitral insufficiency and calcified aortic stenosis in the adult.


Subject(s)
Blood Vessel Prosthesis , Heart Diseases/therapy , Stents , Humans , Publishing/trends
15.
Med Mal Infect ; 36(6): 343-5, 2006 Jun.
Article in French | MEDLINE | ID: mdl-16806779

ABSTRACT

We report a highly probable case of moderately severe blackwater fever. A French woman, living in Guinea Bissau, was used to taking self-medication halofantrine for malaria. On this occasion, she felt unusual chills and pyrexia after a non documented bout of malaria, followed by nausea, then jaundice with dark-red urines despite another treatment with halofantrine. A sepsis was eliminated by two negatives thick peripheral blood drop examinations. Hemolysis was noted with 8.1 g/dl of hemoglobin, Coombs positive, and LDH at 1,452 IU/l, associated to renal failure with 34 ml per minute of clearance. The outcome was favourable with rehydration. Blackwater fever has been described with the three aminoalcohols, but mainly in severe presentations. Clinicians are not familiar with this disease, even though it has major therapeutic implications: quinine, halofantrine, and mefloquine become strictly contra-indicated. Moderate forms may be unknown, and this observation should be taken into account to prevent mistreatment in future patients.


Subject(s)
Antimalarials/therapeutic use , Blackwater Fever/diagnosis , Acute Kidney Injury , Blackwater Fever/blood , Blackwater Fever/drug therapy , Female , Guinea , Hemolysis , Humans , Middle Aged , Treatment Outcome
16.
Rev Pneumol Clin ; 62(6 Pt 1): 407-10, 2006 Dec.
Article in French | MEDLINE | ID: mdl-17242649

ABSTRACT

A 36-year old immunocompetent male from Senegal with an uneventful history was admitted for exploration of a bullous collection in the posterior mediastinum. Multifocal tuberculosis was diagnosed. Computed tomography-guided drainage removed 600 cc of caseum. The diagnosis as rupture of intrathoracic Pott's abscess complicated by a probably esophageal fistula. The clinical course was rapidly favorable with later development of mediastinal fibrosis. This uncommon case illustrates the contribution of interventional radiology recently developed in the Principal Hospital in Dakar, Senegal.


Subject(s)
Abscess/diagnostic imaging , Mediastinal Diseases/diagnostic imaging , Thoracic Vertebrae/diagnostic imaging , Tomography, X-Ray Computed , Tuberculosis, Spinal/diagnostic imaging , Abscess/microbiology , Abscess/surgery , Adult , Drainage , Humans , Male , Mediastinal Diseases/microbiology , Mediastinal Diseases/surgery , Radiology, Interventional , Senegal , Treatment Outcome , Tuberculosis, Spinal/complications , Tuberculosis, Spinal/surgery
17.
Ann Cardiol Angeiol (Paris) ; 65(6): 425-432, 2016 Dec.
Article in French | MEDLINE | ID: mdl-27816175

ABSTRACT

Demographic data point to a substantial proportion of women in the population of elderly patients with an increasing prevalence of aortic stenosis. Implantation of an aortic bioprosthesis via an endovascular approach known as Transcatheter aortic valve implantation (TAVI) in patients presenting with a symptomatic tight aortic stenosis (severe aortic stenosis) (AS) is an alternative therapeutic option to surgical aortic valve replacement in patients at high surgical risk or ineligible for surgery. The literature has shown that this technique seems to be particularly beneficial in female patients. In the Partner A trial, the 1-year mortality rate was significantly lower in women compared to their male counterparts. Other data revealed that although women have a higher risk of experiencing periprocedural complications (vascular events, bleeding and stroke), their outcome is good and often better than that of men. These results are continuously improving thanks to the enhancement of techniques and devices. In view of the published reports reflecting the increasing experience of the teams, it clearly appears that the simplification of TAVI procedures has resulted in improved outcomes. We report here the case of a patient treated by means of a "minimalist" approach to TAVI allowing a reduction of the risks inherent in the procedure. This simplified strategy relies on an optimal use of CT scan findings prior to TAVI. The procedure is carried out under local anesthesia and the main access site is sutured percutaneously (Proglides). The radial artery is used as a secondary access site. Contrast medium is diluted and stimulation is administered via the intraventricular guidewire. Direct stenting is performed when deemed feasible on the basis of CT scan results. Simplified procedures such as these contribute to the improvement of TAVI outcomes. However, further studies focusing on female patients are warranted in order to corroborate these findings.


Subject(s)
Aortic Valve Stenosis/epidemiology , Aortic Valve Stenosis/surgery , Transcatheter Aortic Valve Replacement , Female , Humans , Male , Postoperative Complications/epidemiology , Postoperative Complications/etiology , Prognosis , Risk Factors , Sex Factors , Transcatheter Aortic Valve Replacement/adverse effects , Treatment Outcome
18.
J Mol Biol ; 300(4): 877-87, 2000 Jul 21.
Article in English | MEDLINE | ID: mdl-10891275

ABSTRACT

The homing endonuclease I-PpoI severely bends its DNA target, resulting in significant deformations of the minor and major groove near the scissile phosphate groups. To study the role of conformational changes within the protein catalyst and the DNA substrate, we have determined the structure of the enzyme in the absence of bound DNA, performed gel retardation analyses of DNA binding and bending, and have mutagenized a leucine residue that contacts an adenine nucleotide at the site of cleavage. The structure of the L116A/DNA complex has been determined and the effects of the mutation on affinity and catalysis have been measured. The wild-type protein displays a rigid-body rotation of its individual subunits upon DNA binding. Homing site DNA is not detectably bent in the absence of protein, but is sharply bent in both the wild-type and L116A complexes. These results indicate that binding involves a large distortion of the DNA and a smaller change in protein conformation. Leucine 116 is critical for binding and catalysis: it appears to be important for forming a well-ordered protein-DNA complex at the cleavage site, for maximal deformation of the DNA, and for desolvation of the nucleotide bases that are partially unstacked in the enzyme complex.


Subject(s)
Endodeoxyribonucleases/chemistry , Endodeoxyribonucleases/metabolism , Leucine/metabolism , Amino Acid Substitution/genetics , Base Sequence , Binding Sites , Catalysis , Crystallography, X-Ray , Dimerization , Endodeoxyribonucleases/genetics , Leucine/genetics , Models, Molecular , Molecular Sequence Data , Mutation/genetics , Nucleic Acid Conformation , Protein Binding , Protein Conformation , Rotation , Sequence Alignment , Thermodynamics
19.
Genetics ; 159(2): 609-22, 2001 Oct.
Article in English | MEDLINE | ID: mdl-11606538

ABSTRACT

Little is known about the genes that interact with Ras signaling pathways to regulate morphogenesis. The synthesis of dorsal eggshell structures in Drosophila melanogaster requires multiple rounds of Ras signaling followed by dramatic epithelial sheet movements. We took advantage of this process to identify genes that link patterning and morphogenesis; we screened lethal mutations on the second chromosome for those that could enhance a weak Ras1 eggshell phenotype. Of 1618 lethal P-element mutations tested, 13 showed significant enhancement, resulting in forked and fused dorsal appendages. Our genetic and molecular analyses together with information from the Berkeley Drosophila Genome Project reveal that 11 of these lines carry mutations in previously characterized genes. Three mutations disrupt the known Ras1 cell signaling components Star, Egfr, and Blistered, while one mutation disrupts Sec61beta, implicated in ligand secretion. Seven lines represent cell signaling and cytoskeletal components that are new to the Ras1 pathway; these are Chickadee (Profilin), Tec29, Dreadlocks, POSH, Peanut, Smt3, and MESK2, a suppressor of dominant-negative Ksr. A twelfth insertion disrupts two genes, Nrk, a "neurospecific" receptor tyrosine kinase, and Tpp, which encodes a neuropeptidase. These results suggest that Ras1 signaling during oogenesis involves novel components that may be intimately associated with additional signaling processes and with the reorganization of the cytoskeleton. To determine whether these Ras1 Enhancers function upstream or downstream of the Egf receptor, four mutations were tested for their ability to suppress an activated Egfr construct (lambdatop) expressed in oogenesis exclusively in the follicle cells. Mutations in Star and l(2)43Bb had no significant effect upon the lambdatop eggshell defect whereas smt3 and dock alleles significantly suppressed the lambdatop phenotype.


Subject(s)
Body Patterning , Drosophila melanogaster/metabolism , Morphogenesis , Signal Transduction , Animals , Base Sequence , DNA Primers , DNA Transposable Elements , Drosophila melanogaster/genetics , Drosophila melanogaster/growth & development , Enhancer Elements, Genetic , ErbB Receptors/genetics , Mutation , ras Proteins/genetics , ras Proteins/metabolism
20.
J Mol Med (Berl) ; 75(11-12): 860-6, 1997.
Article in English | MEDLINE | ID: mdl-9428618

ABSTRACT

Heart rate is a function of at least three factors located in the sinus node, including the pacemaker and the activity of the sympathetic and vagal pathways. Heart rate varies during breathing and exercising. The is far from being a purely academic question because, after myocardial infarction or in cardiac insufficiency, reduced heart rate variability (HRV) represents the most valuable prognostic factor. HRV is usually considered index of the sympathovagal balance and is explored using time domain analysis, such as spectral analysis. Nevertheless, methods such as the Fast Fourier Transformation are not applicable to small rodents which have an unstable heart rate with asymmetric oscillations. Nonlinear methods show chaotic behavior under some conditions. A time and frequency domain method of analysis, the Wigner-Villé Transform, has been proposed for the study of HRV in both humans and small rodents, as a compromise between linear and nonlinear methods. We developed a method to quantify both arrhythmias and HRV in unanesthetized rodents. Such a method allows study of the relationship between the physiological parameters and the myocardial phenotype. Ventricular premature beats are more frequent in 16-month-old spontaneously hypertensive rats than in age-matched controls. In addition, HRV is attenuated in spontaneously hypertensive rats, as in compensatory cardiac hypertrophy in humans, and such attenuation is considered a prognostic index. Converting enzyme inhibition reduces in parallel arterial hypertension, cardiac hypertrophy, and ventricular fibrosis; it prevents ventricular premature beats and normalizes heart rate variability. It can be demonstrated that the incidence of ventricular premature beats is linked to the myocardial phenotype in terms of both cardiac hypertrophy and fibrosis. The two factors act as independent variables. HRV is correlated with the incidence of arrhythmias, suggesting that the beneficial effects of converting enzyme inhibition are related to prevention of arrhythmias.


Subject(s)
Heart Rate/physiology , Models, Cardiovascular , Animals , Cardiomegaly/physiopathology , Disease Models, Animal , Humans
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