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Biomedical subjects

R Cohen

Publications and source records attributed to R Cohen.

At least 37 records · Page 2Linked to original sources
PubMed2005

Laparoscopic revisional bariatric surgery: myths and facts.

BACKGROUND: Bariatric surgery is growing worldwide. An increasing number of patients will require revisional procedures because of inadequate weight control, complications, or loss of quality of life. METHODS: From August 1999 to September 2003, 62 patients were submitted to laparoscopic revisional surgery. RESULTS: The primary operations consisted of laparoscopic adjustable gastric banding in 39 cases, banded and nonbanded Roux-en-Y gastric bypass (RYGB) in 17 cases, vertical banded gastroplasty in 4 cases, and biliopancreatic diversion in 2 cases. Although technically demanding, laparoscopic conversion to RYGB was possible in all cases. Mean operative time was 100 min. Mean hospital stay was 77 h. There were no intraoperative or postoperative complications. A good body mass index reduction after the revisional procedure was observed with a 24 month follow-up period. CONCLUSIONS: Laparoscopic revisional bariatric surgery is safe and effective. However, it should be performed only by experienced bariatric and laparoscopic surgeons.

Adult↗
PubMed2005

Optimization of network robustness to waves of targeted and random attacks.

We study the robustness of complex networks to multiple waves of simultaneous (i) targeted attacks in which the highest degree nodes are removed and (ii) random attacks (or failures) in which fractions p(t) and p(r) , respectively, of the nodes are removed until the network collapses. We find that the network design which optimizes network robustness has a bimodal degree distribution, with a fraction r of the nodes having degree k2 = ((k)-1+r)/r and the remainder of the nodes having degree k1=1, where k is the average degree of all the nodes. We find that the optimal value of r is of the order of p(t)/p(r) for p(t)/p(r) << 1.

Journal Article↗
PubMed2005

[Recurrent respiratory tract infections: how should we investigate and treat?].

Recurrent respiratory tract infections are a common reason for visits to primary care practitioners or hospital physicians. They are placed at the junction of several medical specialities: paediatrics, ENT, pneumology, allergology, immunology, infectiology. The great diversity of the laboratory tests requested and on the other hand the proposed treatments, are the consequences of the diversity of the patients encountered and the paucity of the evidence based-medicine studies in this setting. The dilemma is how to identify the child for which recurrent respiratory tract infections are the witness of underlying condition, without performing repeated medical examinations, laboratory tests and treatments for normal children for which immunologic development occurs normally. The essential tools are the history analysis, physical examination and few laboratory tests. The other questions are how to include, for these patients, influenza and pneumococcal vaccines in the immunization program and how to assess the benefit/risk ratio and the cost of surgical treatments. This paper presents the thought of an expert group trying to define the situations where biological tests or treatments are useful.

Child↗
PubMed2005

[Pneumococcal meningitis in France: age and medical risk factors in children].

Streptococcus pneumoniae (Sp) is an important cause of morbidity and mortality among paediatric infectious diseases. The aim of this study is to analyse specific data on Sp meningitis out of the Bacterial Meningitis (BM) French Surveillance Network about mean age of BM cases and clinical features. Overall 367 Sp BM were reported between January 2001 to January 2004 (sex ratio M/F: 1.3), 69.7% were < 2 years old, median age 0.8 year (minmax 0-16.8 years). Before two years old children, 94.1% had no medical risk factor and no underlying conditions: on the other hand, after two years old, these factors were reported in 27% cases (P < 0.001). Mortality rate was 10.9%. On account of a Sp BM's pic at five months, data of the BM French Surveillance Network confirm the necessity of an early vaccination. The vaccine administration at two, three, four months with a booster during the second year, recommended in the vaccinal french calendar, seems particularly adapted to the Sp BM in France.

Adolescent↗
PubMed2005

Interface geometry and molecular junction conductance: geometric fluctuation and stochastic switching.

Metal/molecule/metal transport junctions can transport charge in the elastic scattering (Landauer) regime if the injection gap is large and the molecule is relatively short. Stochastic switching and broad conduction peak distributions have been observed in such junctions. We examine the effect of altering interface geometry on transport, using density functional calculations. For most structures, variations in conductance of order 0-300% are found, but when an atomic wire of Au binds to the molecule, symmetry changes can modify currents by a factor of 10(3).

Journal Article↗
PubMed2004

Hand-assisted laparoscopic splenectomy in the setting of splenomegaly.

BACKGROUND: Hand-assisted laparoscopic surgery (HALS) devices may be well suited to splenectomy in cases of splenomegaly. METHODS: All cases of HALS for splenectomy between 1997 and 2001 were reviewed. Patient characteristics, operative details, and morbidity and mortality were analyzed. RESULTS: HALS for splenectomy was performed in 54 patients. A total of 39 patients with massive splenomegaly (MS) (>600 g) were identified. The average weight of the MS group was 1285 +/- 505 g. There was one (3%) conversion. Operative time was 159 +/- 65 min, estimated blood loss was 257 +/- 240 ml, and length of hospital stay was 5.4 +/- 2.9 days. Morbidity was limited to 13 patients (24%), and there were two postoperative mortalities (5.1%). CONCLUSIONS: HALS for splenectomy in the setting of splenomegaly is feasible and safe. For the surgeon considering a laparoscopic approach in the setting of splenomegaly, a hand-assisted technique is ideally suited for removal of the enlarged spleen.

Adult↗
PubMed2004

[Clinical effectiveness of seven-valent pneumococcal conjugate vaccine (Prevenar) against invasive pneumococcal diseases: prospects for children in France].

A seven-valent pneumococcal polysaccharide-CRM197 carrier protein conjugate vaccine (PNC7V; Prevenar, Wyeth, Paris) targets the serotypes (belonging to serogroups 14, 6, 19, 18, 23, 9, and 4) most often responsible for invasive pneumococcal disease (IPD) among children. A randomized, controlled, double-masked study among 37,868 children in northern California (Northern California Kaiser Permanente, USA) provided a per protocol vaccine efficacy value of 97.7% against invasive pediatric IPD due to the vaccine serotypes. The PNC7V vaccine was registered by the European Agency for the Evaluation of Medicinal Products (EMEA) in October 2000; a favorable "Community Marketing Decision" under the Centralized Procedure was granted in February 2001. PNC7V was recommended for most infants by the Conseil Supérieur d'Hygiène Publique de France in March 2002, on the advice of the Comité Technique des Vaccinations, as S. pneumoniae in children less than 2 years of age is the primary cause of bacterial meningitis and of mortality associated with community-acquired bacterial infections. The theoretical coverage of the vaccine towards pneumococcal invasive disease in France is about 80%, which represents one of the best serotype coverage estimates in Europe, and vaccines serotypes account for 90% of penicillin-nonsusceptible strains. Distinctive characteristics in France in terms of epidemiology, life style, and therapeutic attitudes justify a precise follow up of the consequences of the vaccination on a national level during the coming years. Hence, surveillance programs have been established: (i) to ascertain the future impact of large-scale PNC7V vaccination on invasive pneumococcal disease incidence, (ii) to follow the evolution of carriage and ecology of the pneumococcus, and (iii) to establish an active "vaccinovigilance".

Female↗
PubMed2004

R-type voltage-gated Ca(2+) channel interacts with synaptic proteins and recruits synaptotagmin to the plasma membrane of Xenopus oocytes.

It is well established that syntaxin 1A, synaptosomal-associated protein of 25 kDa (SNAP-25) and synaptotagmin either alone or in combination, modulate the kinetic properties of voltage-gated Ca(2+) channels Ca(v)1.2 (Lc-channel) Ca(v)2.2 (N-type) and Ca(v)2.1 (P/Q-type). The interaction interface was found to reside at the cytosolic II-III domain of the alpha1 subunit of the channels. In this study, we demonstrated a functional coupling of human neuronal Ca(v)2.3 (R-type channel) with syntaxin 1A, SNAP-25 and synaptotagmin in BAPTA injected Xenopus oocytes. The kinetic properties of Ca(v)2.3 assembled with syntaxin 1A, SNAP-25 or synaptotagmin individually differed from Ca(v)2.3 associated with binary complexes syntaxin 1A/SNAP-25, syntaxin 1A/synaptotagmin or SNAP-25/synaptotagmin. Co-expression of Ca(v)2.3 with syntaxin 1A, SNAP-25 and synaptotagmin together, produced a channel with distinctive kinetic properties analogous to excitosome multiprotein complex generated by Ca(v)1.2 and Ca(v)2.2. Exchanging the current-carrying ions altered the kinetics of channel/synaptic proteins interaction, indicating a tight crosstalk formed between the permeation pathway of Ca(v)2.3 and the fusion apparatus during membrane depolarization. This putative coupling could predict how the release site might be organized to allow a rapid communication between the channel and the release machinery. In vivo confocal imaging of oocytes revealed GFP-synaptotagmin at the plasma membrane when the channel was present, as opposed to random distribution in its absence, consistent with Ca(2+)-independent molecular link of synaptotagmin and the channel. Synaptotagmin was detected at the membrane also in oocytes co-expressing the soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs). Both imaging studies and protein-protein interactions in Xenopus oocytes show that channel linkage to synaptotagmin precedes Ca(2+) influx. Altogether, the R-type channel appears to associate with synaptic proteins to generate a multiprotein excitosome complex prior to Ca(2+)-entry. We propose that the distinct kinetics of the Ca(2+)-channel acquired by the close association with the vesicle and the t-SNAREs within the excitosome complex may be essential for depolarization evoked transmitter release.

Animals↗
PubMed2004

Interactive learning in medicine: socrates in electronic clothes.

Traditional lectures have limited ability to maintain attention and to promote changes in behaviour. Active learning, which stimulates the audience to think and participate, may be more effective. We describe our experience with an interactive polling system in lectures to physicians and students. Audience's answers to questions are displayed, providing instant feedback to both lecturer and audience, and promoting the use of case discussions and problem-solving exercises. In our experience, this modality improves the quality of clinical learning and deserves further evaluation.

Bayes Theorem↗
PubMed2003

Multicentre study of the molecular epidemiology, serotypes and antimicrobial susceptibility patterns of invasive Streptococcus pneumoniae invasive isolated from children in the Ille de France area.

Between January 1997 and April 2002, 73 consecutive invasive strains of Streptococcus pneumoniae were isolated from children under 16 years of age in four hospitals in suburban Paris. Their genetic diversity was investigated by serotyping and analysis of pulsed-field gel electrophoresis restriction patterns. Antibiotic susceptibility patterns were analysed by disk susceptibility testing and determination of minimal inhibitory concentrations. The genetic basis of macrolide resistance was investigated by polymerase chain reaction. Studies of penicillin and vancomycin tolerance were performed for each strain. Despite the high prevalence (45.2%) of penicillin-nonsusceptible Streptococcus pneumoniae, resistance to amoxicillin (1.4%) was rare, and no strain was resistant to cefotaxime. Overall, 4.1% of pneumococcal strains were resistant to penicillin. Penicillin or vancomycin tolerance was not detected in any of the 73 strains studied. Of the erythromycin-resistant strains (48%), all but one carried the ermB gene. No strains showing a decreased susceptibility to ciprofloxacin (MIC, >4 mg/l) or overexpressing an efflux pump inhibited by reserpine were isolated. The serotypes found, in order of frequency, were as follows: 18C, 14, 6B, 19F, 19A, 9V, 23F, 1, 7F, 9A, 38. Strains of penicillin-nonsusceptible Streptococcus pneumoniae belonged predominantly to serotypes 14, 6B, 9V, 9A, 23F, 19F and 19A. The seven-valent conjugated vaccine covered 85.5% of the serogroups isolated in children under 2 years of age and 65.6% of the serogroups identified in children over 2 years of age. The genetic analysis showed a high identity for some serotypes, such as 14/9V, 6B and 23F. The use of the seven-valent conjugated vaccine is a critical measure to prevent invasive pneumococci infections in children in the Ille de France area.

Adolescent↗
PubMed2003

Bladder spasm in children after surgery for ureteric reimplantation.

The primary aim of this study was to prospectively investigate whether there was an association between the duration of post-operative catheterisation and the incidence of bladder spasm in children following ureteric reimplantation surgery. A secondary aim was to investigate whether other surgical and post-operative factors had an effect on the incidence of bladder spasm.

Adolescent↗
PubMed2003

[Antipneumococcal vaccines in sickle-cell anemia and asplenia].

TWO MEANS OF PREVENTION: Asplenic and sickle-cell anemia patients are susceptible to infections caused by polysaccharide-encapsulated bacteria, particularly pneumococci, Haemophilus influenzae b, and meningococci. Prevention of these frequent and serious infections depends on antibiotic prophylaxis and vaccination. ANTI-POLYSACCHARIDE PNEUMOCOCCI: Vaccination Pneumo 23 is a 23-valent vaccine corresponding to more than 90% of the pneumococci strains implicated in systemic infections. The efficacy of conjugated polysaccharide vaccines for the prevention of systemic infections, particularly when caused by antibiotic-resistant strains, can optimize the efficacy potential of antibiotic prophylaxis, the immense majority of strains not covered by the conjugated vaccine being susceptible to penicillin. CONJUGATED PNEUMOCOCCAL VACCINE: Prevenar is a seven-valence vaccine which induces a thymodependent antibody response. The efficacy of the conjugated vaccine against systemic infections, particularly antibiotic resistant strains, can have a potentializing effect on antibiotic prophylaxis, the vast majority of the strains not present in the conjugated vaccine being sensitive to penicillin. OTHER VACCINES: Finally, it should be recalled that conjugated antigroup C meningococcal vaccines are recommended for asplenic and sickle-cell anemia patients. In France, the anti-Haemophilus b vaccine is included in the vaccination calendar for all infants.

Adult↗