Sound propagation in a monodisperse bubble cloud: from the crystal to the glass.

We present a theoretical study of the propagation of a monochromatic pressure wave in an unbounded monodisperse bubbly liquid. We begin with the case of a regular bubble array--a bubble crystal--for which we derive a dispersion relation. In order to interpret the different branches of this relation, we introduce a formalism, the radiative picture, which is the adaptation to acoustics of the standard splitting of the electric field in an electrostatic and a radiative part in Coulomb gauge. In the case of an irregular or completely random array--a bubble glass--and at wavelengths large compared to the size of the bubble array spatial inhomogeneities, the difference between order and disorder is not felt by the pressure wave: a dispersion relation still holds, coinciding with that of a bubble crystal with the same bubble size and air volume fraction at the centre of its first Brillouin zone. This relation is discussed and compared to that obtained by Foldy in the framework of his multiscattering approach.

A quality control programme for acute myocardial infarction management in out-of-hospital critical care medicine.

This study, conducted over two time periods, aimed to evaluate the effectiveness of the diffusion of data, implementation of correctives measures and updated protocols in reducing time to reperfusion in acute myocardial infarction (AMI) management in the out-of-hospital setting. Mean (SD) time to hospital admission and to arterial puncture improved (58 (13) vs 67 (18) min, p = 0.03; and 82 (16) vs 95 (29) min, p = 0.02). The study, performed according to quality control programme methodology, showed that the chronology of AMI management could be improved by appropriate interventions and monitoring of intervention times.

Value of computed tomography and lymphography in staging carcinoma of the uterine cervix.

CT scanning was performed on 68 consecutive patients with newly diagnosed, untreated carcinoma of the uterine cervix (FIGO stage IB-IVA). Lymphography was performed in 61 cases. Surgical pathological correlation was obtained in 16 patients. CT and clinical stage accorded only in 68%, mainly because of CT errors in the determination of parametrial involvement. CT detected enlarged lymph nodes in 60.5%, compared to 39.5% of cases with lymphographically demonstrated nodal metastases; this discrepancy resulted mainly from the inability of CT to discriminate benign nodal changes. Our data suggest lymphography as radiological staging procedure in early stage (IB, IIA) carcinoma and the routine use of CT in advanced stage (IIB-IV) disease.

[Results of a national survey about the use of sedation scales in emergency prehospital medicine]. / Résultats d'une enquête nationale évaluant l'utilisation des scores de sédation en médecine préhospitalière.

The primary goal of sedation in emergency prehospital care is to guarantee the security of the mechanically ventilated patients by optimising their adaptation to the respirator. If the French prehospital guidelines are well codified, their applicability in routine clinical practice seem to be rather empirical. The aim of this national survey was to evaluate the use of the clinical sedation scales by the prehospital physicians. This prospective and clinical practice survey was begun in January 2005. An anonymous questionnaire was sent to the physicians working in the 377 Mobile Intensive Care Unit of the 105 French Emergency Medical Service System. The total response rate from physicians was 28% (n=497). Only 29% of the physicians (n=145) declared to use a sedation scale for a mechanically ventilated patient. The Ramsay score was used in 97% of the cases (n=141).The principal reasons given by the physicians for not using the sedation scales were their ignorance in 57% of the cases (n=200) and the systematic choice of a deep sedation in 42% of the cases (n=147). For 18% of them (n=62), the use of sedation scores was considered too complicated. The final results show that the utilisation ratio of the sedation scores is very low in emergency prehospital medicine and suggest that an effort toward improving the use of sedation in prehospital emergency medicine is necessary.

[The tako-tsubo syndrome: therapeutic stakes]. / Le syndrome de tako-tsubo: enjeu thérapeutique.

The authors report the case of 2-old-caucasian women in the pre- and interhospital setting, who presented chest pain with ST segment elevation. Coronary angiography did not show any significant coronary lesion, ventriculography revealed typical aspect of tako-tsubo. It resolved in a short time, with normalisation of the left ventricule function. The tako-tsubo syndrome, or transient left ventricular apical ballooning syndrome, first described by Japanese physicians, is more and more frequently observed in caucasian patients. This cardiomyopathy associates an apical transient dysfunction without any significant coronary lesion. This syndrome is usually observed in elderly women, occurs frequently after acute emotional or physical stress. The clinical presentation looks like an acute coronary syndrome, with chest pain, electrocardiographic changes and moderate cardiac enzymes release. Coronary angiography shows no significant coronary disease and ventriculography a systolic dysfunction with akinesia of middle and apical segments, leading apical ballooning, and basale hyperkinesia. These abnormalities are transient, with quick favorable outcome. The aetiopathegenia is still uncertain. The differential diagnosis with an acute coronary syndrome with thrombosis is not yet possible. Clinical or biological criteria allowing early diagnosis would lead to optimize the therapeutic management.

The bubble cloud as an N-degree of freedom harmonic oscillator.

The dynamics of a two-dimensional N-bubble static cloud is investigated and shown to be well described by an N-degree of freedom harmonic oscillator model, at least at low enough frequencies. Eigenmodes and eigenfrequencies are calculated and compared with experimental results obtained with an assembly of bubbles caught up under a net in a water tank. Accordance is found to be excellent in the frequency range of validity of the model, the limits of which are discussed. An interpretation of the low-frequency branch of Foldy's dispersion relation in bubbly liquids is suggested in terms of "bubble waves" in a quasi-incompressible medium.

Acquisition of multiple antibiotic resistance by Salmonella dublin from the gramnegative hospital flora, in a kidney allograft recipient.

The case of a kidney allograft recipient, who suffered from several episodes of Salmonella dublin sepsis following massive immunosuppressive therapy to overcome a transplant rejection crisis, is presented. The focus of sepsis was the chronic inflamed gallbladder. The Salmonella dublin strain isolated from the blood during the last episode was found to exhibit multiple resistance to antimicrobiol drugs. Because the resistance phenotype was characteristic for the gramnegative flora of the university hospital, it was suggested that transfer of a resistance plasmid, frequently found in gramnegative enterobacterial isolates, to the Salmonella strain had occurred in the patient. The comparative examination of a Klebsiella pneumoniae strain, representing the hospital flora, and Salmonella dublin revealed that both strains produced the aminoglycoside 3'-phosphotransferase type 1, the 2''-nucleotidyltransferase and the 3''-adenylyltransferase, enzymes responsible for resistance to aminoglycoside antibiotics. Furthermore, in both strains a TEM type beta-lactamase was found to render the organism resistant to penicillins and cephalosporins. Transfer experiments showed that the host ranges of the R-plasmids of both strains were identical. Furthermore, both plasmids were found to be the fi+ type. These data support the view of in vivo transfer of an R-plasmid from the enterobacterial hospital flora to a potential pathogen in a patient.

Transposon-mediated multiple antibiotic resistance in Acinetobacter strains.

Acinetobacter calcoaceticus subsp. anitratus, which is unusually resistant to multiple antibiotics, was the cause of an epidemic of respiratory tract infections in patients in an intensive care unit. A representative isolate of the epidemic strain was found to contain the aminoglycoside-modifying enzymes 3-N-acetyltransferase, 3'-phosphotransferase, and 3"-adenylyltransferase, which confer resistance to gentamicin, kanamycin, and streptomycin, respectively. In addition, the strain produced a cephalosporinase and was resistant to penicillins due to the production of a TEM-2 beta-lactamase. The bacterial isolate also exhibited resistance to chloramphenicol, tetracycline, and sulfonamides. The resistant phenotype of this strain was similar to resistance patterns frequently observed in endemic hospital flora, suggesting that the transfer of an R plasmid into Acinetobacter sp. may have occurred. However, antibiotic resistance could not be transferred to any recipient by various mating procedures. After plasmid RP4 was transferred into an ampicillin- and kanamycin-susceptible derivative of the epidemic strain, mobilization of resistance to chloramphenicol, gentamicin, streptomycin, sulfonamides, and possibly tetracycline could be achieved. This mobilization was due to the transposition of a 16-megadalton DNA sequence from the Acinetobacter chromosome into plasmid RP4. Insertion of the transposable sequence occurred near the PstI and SmaI sites around position 22.5 on the physical map of plasmid RP4. We suggest that a plasmid resistant to multiple antibiotics was transferred from the hospital flora into Acinetobacter sp. but could not be maintained stably in this host. Instead, a multiply resistant DNA sequence was transposed and stably integrated into the Acinetobacter chromosome. The occurrence of such multiply resistant transposons on conjugative plasmids contributes greatly to the genetic variability of bacteria and may sometimes have serious epidemiological and therapeutic consequences.

Aminocyclitol-modifying enzymes specified by chromosomal genes in Staphylococcus aureus.

A genetic analysis of aminocyclitol resistance in two strains of Staphylococcus aureus was performed. Resistance of strain FK170, isolated in Zurich, was due to the production of a 3'-phosphotransferase [APH(3')]. Strain 5532, isolated in London, produced a 2"-phosphotransferase [APH(2")] and a 6'-N-acetyltransferase [AAC(6')]. Plasmid deoxyribonucleic acid (DNA) was isolated by isopycnic centrifugation from the two parent strains, as well as from susceptible variants and from resistant transductants of both strains. Comparative analysis of plasmid and from resistant transductants of both strains. Comparative analysis of plasmid DNA by centrifugation in sucrose gradients revealed that strain FK170 harbored a 2.7-megadalton tetracycline R-plasmid and a 36-megadalton cryptic plasmid. Strain 5532 contained an 18.5-megadalton penicillinase plasmid. No evidence for plasmid location of the markers for aminocyclitol resistance could be obtained.

Cell internalization of anionic maghemite nanoparticles: quantitative effect on magnetic resonance imaging.

Anionic iron oxide nanoparticles are efficiently internalized into macrophages where they concentrate within micrometric endosomes, conferring on them a high magnetic susceptibility. The uptake of anionic maghemite nanoparticles by macrophages was quantified by an electron spin resonance (ESR) experiment. MR spin-echo sequences were performed with various TEs and TRs. The contrast enhancement was compared between two types of agarose phantoms with the same equivalent ferrite concentrations but containing either dispersed isolated nanoparticles or magnetically labeled macrophages. It is shown that the intracellular confinement of maghemite nanoparticles within micrometric endosomes results in a significant decrease of the longitudinal relaxivity and a moderate decrease of the transverse relaxivity compared to the relaxivities of the dispersed isolated nanoparticles. As a consequence, the signature of endosomal magnetic labeling consists of a negative contrast on T(1)-weighted images in the whole ferrite concentration range, whereas the presence of extracellular isolated nanoparticles can result in a positive enhancement.