MRI and articular cartilage

There are considerable laboratory data and information from animal and continuous culture in vitro models to support continuous infusion therapy for penicillins and cephalosporins, but, as yet, the only existing clinical data relate to cephalosporins. Penicillins do not exert concentration-dependent killing in the therapeutic range but have a post-antibiotic effect (PAE) against Gram-positive cocci but not Gram-negative rods. Animal models indicate the time (T) during which the serum concentrations exceed the minimum inhibitory concentration (MIC) of the pathogen [T > MIC] determines outcomes. Pharmacokinetic studies in humans indicate that continuous infusion with penicillins is possible but there are no clinical data on efficacy. Cephalosporins have similar pharmacodynamic properties to penicillins; T > MIC determines outcome. Data related to ceftazidime indicate that the drug concentration at steady-state (Css) should exceed the pathogen MIC by > 1-fold and perhaps by 4- to 5-fold or more. Human pharmacokinetics of ceftazidime administered by continuous infusion to a wide variety of patient groups indicates that Css of > 20 mg/L can easily be achieved using conventional daily doses. Clinical data indicate increased effectiveness of a continuous regimen in neutropenic patients with Gram-negative infection. Furthermore cefuroxime administration by continuous infusion has resulted in lower doses and shorter course durations. Little is known of the pharmacodynamics of monobactams and there are few clinical data on continuous infusion therapy. Carbapenems have different pharmacodynamics to other beta-lactams as they have concentration-dependent killing and a PAE with both Gram-positive and Gram-negative bacteria. While T > MIC has a role in determining outcomes, the proportion of the dosing interval for which serum drug concentrations should exceed the pathogen MIC is less than for other beta-lactams. In vitro models have shown that continuous infusion is effective, as is less frequent dosing. There are few data on continuous infusion of carbapenems but some patients have been treated with once-daily dosing. Clinically, continuous infusion therapy with penicillins and cephalosporins should be considered in patients infected with susceptible Gram-negative rods not responding to conventional therapy. As an approximation, the same total daily dose should be given but a bolus intravenous injection should be give at the start of continuous infusion to ensure Css is reached rapidly. The Css may be difficult to predict and determination of serum drug concentrations may be indicated. Ideally, the Css should be calculated based on the MIC of the potential pathogen and may be higher or lower than the Css achieved by a conventional daily dose.     

边走边吃 墨西哥城玉米饼烘焙坊

<正>设计师说,玉米饼烘焙坊(El Expendio de Maíz)的故事缘于三五好友的一次公路旅行。那次,他们决定离开墨西哥城几天,离开在首都的时髦都市生活,去那些乡村僻野,那些没什么旅游者的地方,那些简朴的村庄里,享受简单的食物,体验真实而简单的墨西哥生活,就那么看着人们的日常生活。在墨西哥驱车旅行时,连续行驶七八个小时是很常见的事情。就是说,在某个     

Computed tomographic angiography for the evaluation of carotid artery stenosis

BACKGROUND AND PURPOSE: No previous study has compared the reliability of carotid artery measurement provided by axial images, shaded surface display (SSD), and maximum intensity projection (MIP). METHODS: Helical CT and conventional angiography were performed prospectively in 20 patients with atherosclerotic stenosis of the internal carotid artery. Stenosis measurement was performed in a blinded fashion on angiography and CT by two independent examiners. Calcifications were segmented when they were located far enough from the vascular lumen. SSD and MIP were systematically performed for each carotid bifurcation. We measured stenosis using conventional angiography as standard and the different CT reconstructions (axial images, SSD, and MIP) by comparing the stenosis diameter at its narrowest point to the normal internal carotid artery. The degree of stenosis was classified into six groups: no stenosis, mild stenosis (< 30%), moderate stenosis (30% to 70%), severe stenosis (> 70%), near occlusion, and occlusion (100%). No measurement was made in cases of normal artery, near occlusion, and occlusion. RESULTS: Correlations between angiography and the three types of reconstruction were very good. Axial sections correctly classified the carotid arteries in 95% of cases. In 10 carotid arteries, stenosis was not assessable by SSD and MIP because of calcifications. In the remaining carotid arteries, MIP correctly classified the degree of stenosis in 96% of cases, whereas SSD misclassified 21% of cases. CONCLUSIONS: Our study showed that axial images provide a reliable evaluation of carotid artery stenosis. Calcifications are limiting factors in SSD or MIP. When atherosclerotic plaques are not calcified, MIP reconstructions provide a more reliable measurement of the vascular lumen than SSD.     

Comparison of electrical and atomic profiles of Mg24 and Zn64 implanted gaas samples and GaAs-GaAIAs heterostructures for bipolar transistor applications

The aim of this work is to study the electrical properties of Mg²⁴ and Zn⁶⁴ implanted and annealed samples (semi-insulating GaAs substrates,n ⁺ doped GaAs epilayers, GaAs-GaAlAs heterostructures) with the final objective of realizing the contact region for the p-type base layer of heterojunction bipolar transistor (HBT). We show that, for HBT applications, Mg⁺ is a more suitable candidate because its characteristics (depth, concentration) are easier to control: they are not very sensitive to doping level and composition of different layers. Low specific contact resistivity (<10^-5Ωcm²) have been obtained with Au-Mn alloy on Mg⁺ implanted GaAs.     

1.55-μm polarization-insensitive optical amplifier withstrain-balanced superlattice active layer

A polarization insensitive (sensitivity <1 dB) GaInAs-GaInAsP semiconductor optical amplifier has been realized at 1.55 μm. The active layer consists of a strain-balanced superlattice structure. Gain polarization insensitivity on a large bandwidth (60 nm) together with a 22.5-dB signal gain and a 11-dBm polarization-insensitive saturation output power are obtained     

Macroparticles monitoring for biocontamination prevention

This study investigated a potential correlation between deposited macroparticles?>5µm and bioaerosols. Bioaerosols were detected using both passive (culture plates) and dynamic sampling (biocollectors). Bioaerosols were then revealed visually on culture plates after incubation and counted in colony forming unit (CFU)/cm². Macroparticles were counted on line by CLEAPART-100 (patent CEA – Aix Marseille University – Winlight System). It enables continuous monitoring of the deposit of macroparticles on surfaces. We have shown that those macroparticles could be strongly correlated to viable particle measurements (bacteria and mould) after dynamic sampling by biocollectors. As viable particle measurements require an incubation period of at least 48 hours, it is easy to understand the advantage in continuous macroparticle done by CLEAPART-100. CLEAPART-100 is therefore an instrument which enables the alert to be raised in relation to any contamination or biocontamination events.     

Enantioselective epoxidations catalyzed by zeolite MCM-22 encapsulated Jacobsen's catalyst

A novel method for the encapsulation of homogeneous catalysts within the supercages (7.1×18.2 Å) of zeolite MCM-22 has been developed. By way of example, the well known asymmetric oxidation catalyst (R,R)-N,N-bis(3,5-di-tert-butylsalicylidedene)-1,2-cyclohexanediaminemanganese(III) chloride, a.k.a Jacobsen's catalyst, was occluded in MCM-22 during the zeolite synthesis. This ship-in-a-bottle complex exhibited both higher activity and enantioselectivity for the epoxidation of -methylstyrene compared with the homogeneous catalyst.     

Cerebral fat embolism after closed leg injury

A 21-year-old man sustained a closed fracture of the leg from an industrial accident, without associated head trauma. The orthopaedic treatment consisted of immediate immobilization by setting leg in plaster. Two hours after admission, the Glasgow coma scale score was 10. Four hours after admission he developed a coma (Glasgow coma scale score = 7) with repetitive seizures. No lesion was visible on cerebral CT scan. Chest X-ray was unremarkable. Petechiae on the anterior chest wall and abdomen with bilateral mydriasis occurred. Thrombocytopenia with prothrombine time increase were observed. Magnetic resonance imaging, 27 hours after admission, showed high-intensity areas on T2 weighted views due to fat embolism. Retinal haemorrhages were observed. The bronchoalveolar lavage showing fat staining of tracheal aspirates confirmed the diagnosis of fat embolism. This case report emphasizes the possibility of predominant neurologic manifestations of a fat embolism and the diagnostic help of cerebral magnetic resonance imaging.