Radial transport of nutrients: the plant root as a polarized epithelium.

In higher plants, roots acquire water and soil nutrients and transport them upward to their aerial parts. These functions are closely related to their anatomical structure; water and nutrients entering the root first move radially through several concentric layers of the epidermis, cortex, and endodermis before entering the central cylinder. The endodermis is the innermost cortical cell layer that features rings of hydrophobic cell wall material called the Casparian strips, which functionally resemble tight junctions in animal epithelia. Nutrient uptake from the soil can occur through three different routes that can be interconnected in various ways: the apoplastic route (through the cell wall), the symplastic route (through cellular connections), and a coupled trans-cellular route (involving polarized influx and efflux carriers). This Update presents recent advances in the radial transport of nutrients highlighting the coupled trans-cellular pathway and the roles played by the endodermis as a barrier.

Genetically resistant mice lacking interleukin-12 are susceptible to infection with Leishmania major and mount a polarized Th2 cell response.

Mice with homologous disruption of the gene coding for either the p35 subunit or the p40 subunit of interleukin-12 (IL-12) and derived from a strain genetically resistant to infection with Leishmania major have been used to study further the role of this cytokine in resistance to infection and the differentiation of functional CD4+ T cell subsets in vivo. Wild-type 129/Sv/Ev mice are resistant to infection with L. major showing only small lesions which resolve spontaneously within a few weeks and develop a type 1 CD4+ T cell response. In contrast, mice lacking bioactive IL-12 (IL-12p35-/- and IL-12p40-/-) developed large, progressing lesions. Whereas resistant mice were able to mount a delayed-type hypersensitivity (DTH) response to Leishmania antigen, susceptible BALB/c mice as well as IL-12-deficient 129/Sv/Ev mice did not show any DTH reaction. To characterize the functional phenotype of CD4+ T cells triggered in infected wild-type mice and IL-12-deficient mice, the expression of mRNA for interferon-gamma (IFN-gamma) and interleukin-4 (IL-4) in purified CD4+ lymph node cells was analyzed. Wild-type 129/Sv/Ev mice showed high levels of mRNA for IFN-gamma and low levels of mRNA for IL-4 which is indicative of a Th1 response. In contrast, IL-12- deficient mice and susceptible BALB/c mice developed a strong Th2 response with high levels of IL-4 mRNA and low levels of IFN-gamma mRNA in CD4+ T cells. Similarly, lymph node cells from infected wild-type 129 mice produced predominantly IFN-gamma in response to stimulation with Leishmania antigen in vitro whereas lymph node cells from IL-12-deficient mice and susceptible BALB/c mice produced preferentially IL-4. Taken together, these results confirm in vivo the importance of IL-12 in induction of Th1 responses and protective immunity against L. major.

Usefulness of double locus sequence typing (DLST) for regional and international epidemiological surveillance of methicilin-resistant Staphylococcus aureus.

Methicillin-resistant Staphylococcus aureus (MRSA) is a major cause of nosocomial infections worldwide. To differentiate reliably among S. aureus isolates, we recently developed double locus sequence typing (DLST) based on the analysis of partial sequences of clfB and spa genes. In the present study, we evaluated the usefulness of DLST for epidemiological investigations of MRSA by routinely typing 1242 strains isolated in Western Switzerland. Additionally, particular local and international collections were typed by pulsed field gel electrophoresis (PFGE) and DLST to check the compatibility of DLST with the results obtained by PFGE, and for international comparisons. Using DLST, we identified the major MRSA clones of Western Switzerland, and demonstrated the close relationship between local and international clones. The congruence of 88% between the major PFGE and DLST clones indicated that our results obtained by DLST were compatible with earlier results obtained by PFGE. DLST could thus easily be incorporated in a routine surveillance procedure. In addition, the unambiguous definition of DLST types makes this method more suitable than PFGE for long-term epidemiological surveillance. Finally, the comparison of the results obtained by DLST, multilocus sequence typing, PFGE, Staphylococcal cassette chromosome mec typing and the detection of Panton-Valentine leukocidin genes indicated that no typing scheme should be used on its own. It is only the combination of data from different methods that gives the best chance of describing precisely the epidemiology and phylogeny of MRSA.

Double Concentric Autofluorescence Ring in NR2E3-p.G56R-linked Autosomal Dominant Retinitis Pigmentosa.

Purpose: We report an unusual appearance of fundus autofluorescence (FAF) associated with NR2E3-p.G56R-linked autosomal dominant retinitis pigmentosa (ADRP).Methods: Patients were enrolled among three generations in a Swiss family. Molecular diagnosis identified a c.166G>A (p.G56R) mutation. Ophthalmic examination included fundus photography, FAF, near-infrared autofluorescence (NIA), optical coherence tomography (OCT) and visual fields (VF).Results: Fundus examination revealed a wide range of features from unremarkable to attenuated arterial caliber, clumped and spicular pigment deposits in the mid-periphery and optic nerve pallor. FAF showed a double concentric hyperautofluorescent ring: an inner perimacular ring which tended to be smaller in older patients, and an outer ring located along the vascular arcades, which appeared to extend over time towards the periphery and eventually became hypoautofluorescent. The inner and outer hyperautofluorescent rings were seen both on NIA and FAF at a similar localization. There was also a spatial correspondence between the loss of photoreceptor inner segment and outer segment junction on OCT and the area delimited by both double FAF and NIA rings. VF showed either midperipheral annular scotoma or constricted visual field loss in advanced cases, correlating with dystrophic non-functional retinal regions demarcated by the hyperautofluorescent annuli. A double ring of hyperautofluorescence was observed in all but one patient of two additional families, but not in patients harboring mutations in other ADRP genes, including PRPF3, RHO, RP1, PRPH2, PROM1 and CTRP5.Conclusions: The presence of a double concentric hyperautofluorescent ring of FAF may represent a highly penetrant early phenotypic marker of NR2E3-p.G56R-linked ADRP.

Repeated Double-Poling Sprint Training in Hypoxia by Competitive Cross-country Skiers.

PURPOSE: Repeated-sprint training in hypoxia (RSH) was recently shown to improve repeated-sprint ability (RSA) in cycling. This phenomenon is likely to reflect fiber type-dependent, compensatory vasodilation, and therefore, our hypothesis was that RSH is even more beneficial for activities involving upper body muscles, such as double poling during cross-country skiing. METHODS: In a double-blinded fashion, 17 competitive cross-country skiers performed six sessions of repeated sprints (each consisting of four sets of five 10-s sprints, with 20-s intervals of recovery) either in normoxia (RSN, 300 m; FiO2, 20.9%; n = 8) or normobaric hypoxia (RSH, 3000 m; FiO2, 13.8 %; n = 9). Before (pre) and after (post) training, performance was evaluated with an RSA test (10-s all-out sprints-20-s recovery, until peak power output declined by 30%) and a simulated team sprint (team sprint, 3 × 3-min all-out with 3-min rest) on a double-poling ergometer. Triceps brachii oxygenation was measured by near-infrared spectroscopy. RESULTS: From pretraining to posttraining, peak power output in the RSA was increased (P < 0.01) to the same extent (29% ± 13% vs 26% ± 18%, nonsignificant) in RSH and in RSN whereas the number of sprints performed was enhanced in RSH (10.9 ± 5.2 vs 17.1 ± 6.8, P < 0.01) but not in RSN (11.6 ± 5.3 vs 11.7 ± 4.3, nonsignificant). In addition, the amplitude in total hemoglobin variations during sprints throughout RSA rose more in RSH (P < 0.01). Similarly, the average power output during all team sprints improved by 11% ± 9% in RSH and 15% ± 7% in RSN. CONCLUSIONS: Our findings reveal greater improvement in the performance of repeated double-poling sprints, together with larger variations in the perfusion of upper body muscles in RSH compared with those in RSN.

Psychiatrie sous double contrainte, enjeux de la planification en santé mentale [Psychiatry under double bind, issue of the planification in mental health]

Given the important modifications of the "Loi sur l'Assurance maladie (LAMal)", this article gives a contribution to the hospital planification by identifying the main factors that have determined the current organisation of the psychiatric care network. We notice a gap between the orientations of these networks and the funding scheme forecast in the framework of the LAMal. In order to preserve the progressions of these last years and to avoid the negative effects of a too restrictive funding act for the assignment of the public psychiatry, the planification must result in a consensus between the state, the insurances and the multiple actors of the mental health. Otherwise, this will be done to the detriment of the activities of secondary prevention, of coordination in the network, of support to the natural helpers, and of intervention to the vulnerable populations.

Double-bundle transtibial posterior cruciate ligament reconstruction with a tendon-patellar bone-semitendinosus tendon autograft: clinical results with a minimum of 2 years' follow-up.

PURPOSE: The purpose of this study was to evaluate the clinical and subjective outcomes after arthroscopic-assisted double-bundle posterior cruciate ligament (PCL) reconstruction. METHODS: A series of 15 patients with grade III isolated chronic PCL tears underwent double-bundle PCL reconstruction. Of these patients, 8 (53%) had simultaneous fractures. The mean time from accident to surgery was 10.8 months (range, 8 to 15 months). The mean age at the time of surgery was 28.2 years (range, 17 to 43 years). All of the patients reported knee insecurity during activities of daily living or light sporting activities, with associated anterior knee pain in 5 patients. Preoperatively, posterolateral or posteromedial corner injuries were ruled out through accurate clinical examination. The knees were assessed before surgery and at a mean follow-up of 3.2 years (range, 2 to 5 years) with a physical examination, 4 different rating scales, and stress radiographs obtained with a Telos device (Telos, Marburg, Germany). RESULTS: Postoperative physical examination revealed a reduction of the posterior drawer and tibial step-off in all cases, although the posterior laxity was not completely normalized. Nevertheless, the patients were subjectively better after surgery. The subjective International Knee Documentation Committee score was significantly ameliorated. With regard to the objective International Knee Documentation Committee score, 6 knees (40%) were graded as abnormal because of posterior displacement of 6 mm or greater on follow-up stress radiographs with the Telos device. On the Lysholm knee scoring scale, the score was excellent in 13% of patients and good in 87%. The mean score on the Hospital for Special Surgery knee ligament rating scale was 85.8. The Tegner activity score showed an amelioration after surgery, but no patient resumed his or her preinjury level of activities. The postoperative stress radiographs revealed an improvement in posterior instability of 50% or more in all but 3 knees (20%). CONCLUSIONS: Our technique of double-bundle PCL reconstruction produced a significant reduction in knee symptoms and allowed the patients to return to moderate or strenuous activity, although the posterior tibial translation was not completely normalized and our results appear to be no better than the results of single-bundle PCL reconstruction. LEVEL OF EVIDENCE: Level IV, therapeutic case series.

Echo-time independent signal modulations for strongly coupled systems in triple echo localization schemes: an extension of S-PRESS editing.

The double spin-echo point resolved spectroscopy sequence (PRESS) is a widely used method and standard in clinical MR spectroscopy. Existence of important J-modulations at constant echo times, depending on the temporal delays between the rf-pulses, have been demonstrated recently for strongly coupled spin systems and were exploited for difference editing, removing singlets from the spectrum (strong-coupling PRESS, S-PRESS). A drawback of this method for in vivo applications is that large signal modulations needed for difference editing occur only at relatively long echo times. In this work we demonstrate that, by simply adding a third refocusing pulse (3S-PRESS), difference editing becomes possible at substantially shorter echo times while, as applied to citrate, more favorable lineshapes can be obtained. For the example of an AB system an analytical description of the MR signal, obtained with this triple refocusing sequence (3S-PRESS), is provided.

A double layer model of the gas bubble/water interface

Zeta potential is a physico-chemical parameter of particular importance to describe sorption of contaminants at the surface of gas bubbles. Nevertheless, the interpretation of electrophoretic mobilities of gas bubbles is complex. This is due to the specific behavior of the gas at interface and to the excess of electrical charge at interface, which is responsible for surface conductivity. We developed a surface complexation model based on the presence of negative surface sites because the balance of accepting and donating hydrogen bonds is broken at interface. By considering protons adsorbed on these sites followed by a diffuse layer, the electrical potential at the head-end of the diffuse layer is computed and considered to be equal to the zeta potential. The predicted zeta potential values are in very good agreement with the experimental data of H-2 bubbles for a broad range of pH and NaCl concentrations. This implies that the shear plane is located at the head-end of the diffuse layer, contradicting the assumption of the presence of a stagnant diffuse layer at the gas/water interface. Our model also successfully predicts the surface tension of air bubbles in a KCl solution. (c) 2012 Elsevier Inc. All rights reserved.

A novel protein family mediates Casparian strip formation in the endodermis.

Polarized epithelia are fundamental to multicellular life. In animal epithelia, conserved junctional complexes establish membrane diffusion barriers, cellular adherence and sealing of the extracellular space. Plant cellular barriers are of independent evolutionary origin. The root endodermis strongly resembles a polarized epithelium and functions in nutrient uptake and stress resistance. Its defining features are the Casparian strips, belts of specialized cell wall material that generate an extracellular diffusion barrier. The mechanisms localizing Casparian strips are unknown. Here we identify and characterize a family of transmembrane proteins of previously unknown function. These 'CASPs' (Casparian strip membrane domain proteins) specifically mark a membrane domain that predicts the formation of Casparian strips. CASP1 displays numerous features required for a constituent of a plant junctional complex: it forms complexes with other CASPs; it becomes immobile upon localization; and it sediments like a large polymer. CASP double mutants display disorganized Casparian strips, demonstrating a role for CASPs in structuring and localizing this cell wall modification. To our knowledge, CASPs are the first molecular factors that are shown to establish a plasma membrane and extracellular diffusion barrier in plants, and represent a novel way of epithelial barrier formation in eukaryotes.

The alpha(1A/C)- and alpha(1B)-adrenergic receptors are required for physiological cardiac hypertrophy in the double-knockout mouse.

Catecholamines and alpha(1)-adrenergic receptors (alpha(1)-ARs) cause cardiac hypertrophy in cultured myocytes and transgenic mice, but heart size is normal in single KOs of the main alpha(1)-AR subtypes, alpha(1A/C) and alpha(1B). Here we tested whether alpha(1)-ARs are required for developmental cardiac hypertrophy by generating alpha(1A/C) and alpha(1B) double KO (ABKO) mice, which had no cardiac alpha(1)-AR binding. In male ABKO mice, heart growth after weaning was 40% less than in WT, and the smaller heart was due to smaller myocytes. Body and other organ weights were unchanged, indicating a specific effect on the heart. Blood pressure in ABKO mice was the same as in WT, showing that the smaller heart was not due to decreased load. Contractile function was normal by echocardiography in awake mice, but the smaller heart and a slower heart rate reduced cardiac output. alpha(1)-AR stimulation did not activate extracellular signal-regulated kinase (Erk) and downstream kinases in ABKO myocytes, and basal Erk activity was lower in the intact ABKO heart. In female ABKO mice, heart size was normal, even after ovariectomy. Male ABKO mice had reduced exercise capacity and increased mortality with pressure overload. Thus, alpha(1)-ARs in male mice are required for the physiological hypertrophy of normal postnatal cardiac development and for an adaptive response to cardiac stress.