Contribution à l'étude du rhizome et des rejets du bananier

Une étude a été entreprise à la Martinique sur le rhizome du bananier et l'émission des rejets. Les observations ont permis de constater que les racines actives sont groupées au niveau du collet, la forme de la souche et sa position par rapport à la surface du sol sont fonction du type de sol, de la profondeur de plantation et des facteurs climatiques. L'émission des rejets paraît se faire le plus souvent, tout au moins pour les 7 premiers en des points donnés de la souche et selon un ordre donné. Des trois types de rejets: axial, latéral, et terminal, on a particulièrement étudié le rejet axial. C'est celui qui est émis par la souche en cours de développement à l'opposé de la souche mère, celle-ci se trouvant donc avec la souche du porteur et le rejet sur une même ligne appelée axe. C'est le rejet généralement le premier formé, le plus profond et le plus vigoureux, le rejet successeur par excellence, qui permettrait de plus, si toutes les souches ont été plantées dans le même sens au départ, de maintenir les alignements quand la bananeraie vieilli

A case of severe osteomalacia secondary to phosphate diabetes in a renal transplant recipient

Transient hypophosphatemia is frequently observed during the first months after renal transplantation and is usually asymptomatic. Phosphate diabetes is defined as inadequate tubular phosphorus reabsorption leading to persistent renal phosphorus wasting, which is an important but overlooked cause of osteodystrophy in the post-renal transplantation population. We report the case of a 58-year-old male who presented with severe multiple osteoarticular pains within 3 months after successful first kidney transplantation. Bone disease was attributed initially to mild hyperparathyroidism secondary to vitamin D deficiency. Despite the correction of the hyperparathyroidism, the withdrawal of corticosteroids, and the reduction of immunosuppressive treatment to tacrolimus-based monotherapy, the osteoarticular pains persisted. Skeletal investigations at month 9 post-transplantation demonstrated a significant bone mineral density loss associated with osteomalacia and osteoporosis on the bone biopsy. Laboratory data showed persistent hypophosphatemia, and phosphate diabetes was then diagnosed explaining the post-transplant bone disease. A tacrolimus-induced renal tubular disorder was suspected to contribute to the excessive renal phosphorus wasting. The replacement of tacrolimus by sirolimus, in addition to oral phosphorus and vitamin D supplementations, led to the disappearance of pains, the normalization of urinary and plasma phosphate level, and a significant improvement of bone mineralization

Kinetics of sickle cell biorheology and implications for painful vasoocclusive crisis

We developed a microfluidics-based model to quantify cell-level processes modulating the pathophysiology of sickle cell disease (SCD). This in vitro model enabled quantitative investigations of the kinetics of cell sickling, unsickling, and cell rheology. We created short-term and long-term hypoxic conditions to simulate normal and retarded transit scenarios in microvasculature. Using blood samples from 25 SCD patients with sickle hemoglobin (HbS) levels varying from 64 to 90.1%, we investigated how cell biophysical alterations during blood flow correlated with hematological parameters, HbS level, and hydroxyurea (HU) therapy. From these measurements, we identified two severe cases of SCD that were also independently validated as severe from a genotype-based disease severity classification. These results point to the potential of this method as a diagnostic indicator of disease severity. In addition, we investigated the role of cell density in the kinetics of cell sickling. We observed an effect of HU therapy mainly in relatively dense cell populations, and that the sickled fraction increased with cell density. These results lend support to the possibility that the microfluidic platform developed here offers a unique and quantitative approach to assess the kinetic, rheological, and hematological factors involved in vasoocclusive events associated with SCD and to develop alternative diagnostic tools for disease severity to supplement other methods. Such insights may also lead to a better understanding of the pathogenic basis and mechanism of drug response in SCD.National Institutes of Health (U.S.) (R01HL094270)National Institutes of Health (U.S.) (U01HL114476

Severe episodes of extra cellular dehydration : an atypical adult presentation of cystic fibrosis

Cystic fibrosis (CF) is usually diagnosed during childhood by respiratory or gastro-intestinal symptoms. Hyponatremic hypochloremic dehydration with metabolic alkalosis is a rare but typical presentation of CF in infants. In contrast, only 3 cases have been described in adults. We report a case of CF in a 33-year-old Caucasian female presenting with a severe sodium and chloride depletion caused by inappropriate sweating. She experienced three episodes of severe dehydration before the diagnosis was suspected. Sweat chloride test was pathological and mild pulmonary involvement was found on CT scan. AF508 mutation and a rare mutation (3849+40 A/G) on the intron 19 of CFTR gene were found. Interestingly, our patient has a heterozygote twin sister, carrier of the same mutations of CFTR gene who also developed CF but with a different phenotype. We suspect modifier genes to be implicated in the differences observed between the two phenotypes. We discuss the physiopathology of electrolyte disturbance and review the other similar adults cases

Solid-Phase Synthesis of Arylpiperazine Derivatives and Implementation of the Distributed Drug Discovery (D3) Project in the Search for CNS Agents

We have successfully implemented the concept of Distributed Drug Discovery (D3) in the search for CNS agents. Herein, we demonstrate, for the first time, student engagement from different sites around the globe in the development of new biologically active compounds. As an outcome we have synthesized a 24-membered library of arylpiperazine derivatives targeted to 5-HT1A and 5-HT2A receptors. The synthesis was simultaneously performed on BAL-MBHA-PS resin in Poland and the United States, and on BAL-PS-SynPhase Lanterns in France. The D3 project strategy opens the possibility of obtaining potent 5-HT1A/5-HT2A agents in a distributed fashion. While the biological testing is still centralized, this combination of distributed synthesis with screening will enable a D3 network of students world-wide to participate, as part of their education, in the synthesis and testing of this class of biologically active compounds

Acoustic separation of circulating tumor cells

Circulating tumor cells (CTCs) are important targets for cancer biology studies. To further elucidate the role of CTCs in cancer metastasis and prognosis, effective methods for isolating extremely rare tumor cells from peripheral blood must be developed. Acoustic-based methods, which are known to preserve the integrity, functionality, and viability of biological cells using label-free and contact-free sorting, have thus far not been successfully developed to isolate rare CTCs using clinical samples from cancer patients owing to technical constraints, insufficient throughput, and lack of long-term device stability. In this work, we demonstrate the development of an acoustic-based microfluidic device that is capable of high-throughput separation of CTCs from peripheral blood samples obtained from cancer patients. Our method uses tilted-angle standing surface acoustic waves. Parametric numerical simulations were performed to design optimum device geometry, tilt angle, and cell throughput that is more than 20 times higher than previously possible for such devices. We first validated the capability of this device by successfully separating low concentrations (~100 cells/mL) of a variety of cancer cells from cell culture lines from WBCs with a recovery rate better than 83%. We then demonstrated the isolation of CTCs in blood samples obtained from patients with breast cancer. Our acoustic-based separation method thus offers the potential to serve as an invaluable supplemental tool in cancer research, diagnostics, drug efficacy assessment, and therapeutics owing to its excellent biocompatibility, simple design, and label-free automated operation while offering the capability to isolate rare CTCs in a viable state.National Institutes of Health (U.S.) (Grant 1 R01 GM112048-01A1)National Institutes of Health (U.S.) (Grant 1R33EB019785-01)National Science Foundation (U.S.)Penn State Center for Nanoscale Science (Materials Research Science and Engineering Center Grant DMR-0820404)National Institutes of Health (U.S.) (Grant U01HL114476

Cellular normoxic biophysical markers of hydroxyurea treatment in sickle cell disease

Hydroxyurea (HU) has been used clinically to reduce the frequency of painful crisis and the need for blood transfusion in sickle cell disease (SCD) patients. However, the mechanisms underlying such beneficial effects of HU treatment are still not fully understood. Studies have indicated a weak correlation between clinical outcome and molecular markers, and the scientific quest to develop companion biophysical markers have mostly targeted studies of blood properties under hypoxia. Using a common-path interferometric technique, we measure biomechanical and morphological properties of individual red blood cells in SCD patients as a function of cell density, and investigate the correlation of these biophysical properties with drug intake as well as other clinically measured parameters. Our results show that patient-specific HU effects on the cellular biophysical properties are detectable at normoxia, and that these properties are strongly correlated with the clinically measured mean cellular volume rather than fetal hemoglobin level.National Institutes of Health (U.S.) (Grant 1R01HL121386-01A1)National Institutes of Health (U.S.) (Grant 9P41EB015871-26A1)National Institutes of Health (U.S.) (Grant 5R01NS051320)National Institutes of Health (U.S.) (Grant 5U01HL114476)National Institutes of Health (U.S.) (Grant 4R44EB012415)National Science Foundation (U.S.) (Grant CBET-0939511