Monopolar Cautery Use in Pediatric Cochlear Implant Users.

OBJECTIVES: To determine the incidence and impact of monopolar cautery use in a cohort of pediatric cochlear implant (CI) users. STUDY DESIGN: Case series from a retrospective chart review and a systematic review of the literature. SETTING: Tertiary academic referral center. METHODS: CI patient charts from 2012 to 2021 were reviewed from a single pediatric hospital system to determine if monopolar cautery was used during a subsequent surgical procedure. In addition, a systematic review of the literature was performed to identify additional, relevant patients. Postoperative CI function was the primary outcome measure. RESULTS: In total, 190 patients underwent a surgical procedure following cochlear implantation in a single pediatric hospital system. Fifteen patients (7.9%) and 17 distinct surgical procedures were identified in which monopolar cautery was used. Seven of these 17 cases (41.2%) involved the head and neck, and 10 were performed below the clavicles. No patients experienced a device failure or a decline in CI performance following surgery. A systematic review identified an additional 4 patients who underwent a surgery that used monopolar cautery following cochlear implantation, and no change in CI function was identified. CONCLUSIONS: The present study adds additional support to the notion that monopolar cautery does not necessarily injure CI functionality. While the most risk adverse strategy when planning a surgical procedure for a CI patient is to avoid monopolar cautery use altogether, the use of cautery should not immediately be associated with implant dysfunction.

Effects of Fenoldopam in the Pediatric Population: Fluid Status, Serum Biomarkers, and Hemodynamics: A Systematic Review and Meta-Analysis.

Fluid overload is a frequent complication in children during critical illness. Fluid restriction and diuretic agents have been the mainstay therapies so far. Fenoldopam, a selective dopamine-1 receptor agonist, is a diuretic agent with promising effects in the pediatric population. The purpose of this meta-analysis is to evaluate the outcomes of pediatric patients who received fenoldopam. We hypothesized that the administration of fenoldopam will cause an increase in urine output and decrease in serum creatinine in this patient population. A comprehensive database search of PubMed, EMBASE, and Cochrane libraries from the databases' inception through December 2018 was undertaken. Independent reviewers selected appropriate studies and the reviewed data. A meta-analysis was then conducted to determine the effects of fenoldopam on hemodynamics, the amount of vasoactive support, and renal function in children under the critical care setting. The selected end points were measured prior to the administration of fenoldopam and 24 hours after the initiation of the infusion: urine output, serum creatinine, serum sodium, inotrope score, heart rate, central venous pressure, systolic blood pressure, and mean blood pressure. Forest plots were generated to demonstrate individual study data as well as pooled data for each end point. A total of five studies (three retrospective cohort studies, two randomized trials) with 121 patients were included for analysis. No significant difference was observed in urine output, inotrope score, systolic blood pressure, or mean blood pressure. There was a statistically significant increase in serum creatinine and central venous pressure. There was statistically significant decrease in serum sodium and heart rate, and central venous pressure. This meta-analysis did not identify significant renoprotective or vasodilator effects from fenoldopam in this patient population. Although mild electrolyte and hemodynamic changes were identified, larger studies are warranted to determine the clinical significance of fenoldopam in this patient population.

[Treatment of radiation-induced late effects: What's new?] / Traitement des effets tardifs après la radiothérapie : quoi de neuf ?

Mechanisms of late radio-induced lesions are the result of multiple and complex phenomena, with many entangled cellular and tissue factors. The biological continuum between acute and late radio-induced effects will be described, with firstly a break in homeostasis that leads to cellular redistributions. New insights into late toxicity will finally be addressed. Individual radiosensitivity is a primary factor for the development of late toxicity, and clinicians urgently need predictive tests to offer truly personalized radiation therapy. An update will be made on the various functional and genetic tests currently being validated. The management of radio-induced side effects remains a frequent issue for radiation oncologists, and an update will be made for certain specific clinical situations. Finally, an innovative management for patients with significant side effects after pelvic radiotherapy will be developed, involved mesenchymal stem cell transplantation, with the presentation of the "PRISME" protocol currently open to patients recruitment.

[Mesenchymal stem cells and rheumatism. State of the art]. / Mesenchymale Stammzellen und Rheuma. "State of the art".

Mesenchymal stem cells (MSC) are multipotent. They are able to regenerate tissue damage and, in parallel, inhibit inflammation and fibrosis. As they are non-immunogenic, MSCs can be safely transplanted using autologous and allogeneic procedures: an option for refractory connective tissue diseases and osteoarthritis.

Early lesions induced in rat colon epithelium by N-methyl-N'-nitro-N-nitrosoguanidine.

The development of ACF (aberrant crypt foci), adenoma and cancer following intrarectal administration of the alkylating agent N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) has been described. However, microscopic lesions not previously reported were observed as soon as two weeks following carcinogen treatment. These lesions protrude slightly over the epithelial lining of the colon, with a micropolyp-like appearance. Oriented sections show that the centre of these lesions present pseudo-"cystic" appearance, with disorganized crypts made of normal cells. The chorion of the lesion is invaded by numerous inflammatory cells and some ACF may be present nearby. The epithelium lining the cysts and the distorted crypts shows expression of gastric mucin M1/MUC5AC, an early marker of colonic carcinogenesis which is not present in normal colon. This mucin is retained within the "cysts" together with some inflammatory cells. The micropolyps observed contain in a minute form some histological elements described in ulcerative colitis or short-term radiotherapy (distortion of crypts, crypt abscesses, increase of chorion cellularity, infiltration by immune cells). In addition, the presence of bifid crypts nearby suggests mucosal regeneration. Our hypothesis is that these modifications are steps in a normal healing pathway that may in some cases degenerate into precancerous lesions and cancer.

Mesenchymal stem cells improve small intestinal integrity through regulation of endogenous epithelial cell homeostasis.

Patients who undergo pelvic or abdominal radiotherapy may develop acute and/or chronic side effects resulting from gastrointestinal tract (GIT) alterations. In this study, we address the question of the regenerative capability of mesenchymal stem cells (MSC) after radiation-induced GIT injury. We also propose cellular targets of MSC therapy. We report that the infusion of human bone marrow-derived MSC (hMSC) provides a therapeutic benefit to NOD/SCID mice undergoing radiation-induced GIT failure. We observed that hMSC treatment brings about fast recovery of the small intestine (structure and function) in mice with reversible alterations and extends the life of mice with irreversible GIT disorders. The effects of hMSC are a consequence of their ability to improve the renewal capability of small intestinal epithelium. hMSC treatment favors the re-establishment of cellular homeostasis by both increasing endogenous proliferation processes (Ki67 immunostaining) and inhibiting apoptosis (TUNEL staining) of radiation-induced small intestinal epithelial cells. Our results suggest that MSC infusion may be used as a therapeutic treatment to limit radiation-induced GIT damage.

Selected Stro-1-enriched bone marrow stromal cells display a major suppressive effect on lymphocyte proliferation.

Mesenchymal stem cells (MSCs) have an immunosuppressive effect and can inhibit the proliferation of alloreactive T cells in vitro and in vivo. Cotransplantation of MSCs and hematopoietic stem cells (HSCs) from HLA-identical siblings has been shown to reduce the incidence of acute graft-vs.-host disease. MSCs are heterogeneous and data on the inhibitory effects of different MSC subsets are lacking. The antigen Stro1 is a marker for a pure primitive MSC subset. We investigated whether Stro-1-enriched induce a more significant suppressive effect on lymphocytes in a mixed lymphocyte reaction (MLR), and whether this action is related to a specific gene expression profile in Stro-1-enriched compared to other MSCs. We demonstrated that the Stro-1-enriched population elicits a significantly more profound dose-dependent inhibition of lymphocyte proliferation in a MLR than MSCs. One thousand expanded Stro-1-enriched induced an inhibitory effect comparable to that of 10 times as many MSCs. Inhibition by Stro-1-enriched was more significant in contact-dependent cultures than in noncontact-dependant cultures at higher ratio. The Stro-1-enriched inhibitory effect in both culture types was linked to increased gene expression for soluble inhibitory factors such as interleukin-8 (IL-8), leukemia inhibitory factor (LIF), indoleamine oxidase (IDO), human leukocyte antigen-G (HLA-G), and vascular cell adhesion molecule (VCAM1). However, tumor growth factor-beta1 (TGF-beta) and IL-10 were only up-regulated in contact-dependant cultures. These results may support using a purified Stro-1-enriched population to augment the suppressive effect in allogeneic transplantation.

New approach to radiation burn treatment by dosimetry-guided surgery combined with autologous mesenchymal stem cell therapy.

The therapeutic management of severe radiation burns remains a challenging issue. Conventional surgical treatment (excision and skin autograft or rotation flap) often fails to prevent unpredictable and uncontrolled extension of the radiation necrotic process. We report here an innovative therapeutic strategy applied to the victim of a radiation accident (December 15, 2005) with an iridium gammagraphy radioactive source (192Ir, 3.3 TBq). The approach combined numerical dosimetry-guided surgery with cellular therapy using mesenchymal stem cells. A very severe buttock radiation burn (2000 Gy at the center of the skin surface lesion) of a 27-year-old Chilean victim was widely excised (10 cm in diameter) using a physical and anatomical dose reconstruction in order to better define the limit of the surgical excision in apparently healthy tissues. A secondary extension of the radiation necrosis led to a new excision of fibronecrotic tissues associated with a local cellular therapy using autologous expanded mesenchymal stem cells as a source of trophic factors to promote tissue regeneration. Bone marrow-derived mesenchymal stem cells were expanded according to a clinical-grade technique using closed culture devices and serum-free medium enriched in human platelet lysate. The clinical evolution (radiation pain and healing progression) was favorable and no recurrence of radiation inflammatory waves was observed during the 11 month patient's follow-up. This novel multidisciplinary therapeutic approach combining physical techniques, surgical procedures and cellular therapy with adult stem cells may be of clinical relevance for improving the medical management of severe localized irradiations. It may open new prospects in the field of radiotherapy complications.

Human mesenchymal stem cells home specifically to radiation-injured tissues in a non-obese diabetes/severe combined immunodeficiency mouse model.

The therapeutic potential of bone marrow-derived human mesenchymal stem cells (hMSC) has recently been brought into the spotlights of many fields of research. One possible application of the approach is the repair of tissue injuries related to side effects of radiotherapy. The first challenge in cell therapy is to assess the quality of the cell and the ability to retain their differentiation potential during the expansion process. Efficient delivery to the sites of intended action is also necessary. We addressed both challenges using hMSC cultured and then infused to non-obese diabetes/severe combined immunodeficiency (NOD/SCID) mice submitted to total body irradiation. Furthermore, we tested the impact of additional abdominal irradiation superimposed to total body irradiation (TBI), as a model of local therapeutic irradiation. Our results showed that the hMSC used for transplant have been expanded without significant loss in their differentiation capacities. After transplantation into adult unconditioned mice, hMSC not only migrate in bone marrow but also into other tissues. Total body irradiation increased hMSC implantation in bone marrow and muscle and further led to engraftment in brain, heart and liver. Local irradiation in addition to TBI, increased homing of injected cells to the injured tissues and to other tissues outside the local irradiation field. Morphological recovery of irradiated tissues after MSC transplantation and/or differentiation of MSC into specific organ cell types needs to be investigated. This study suggests that using the potential of hMSC to home to various organs in response to tissue injuries might be a strategy to repair the radiation-induced damages.

Persistence of altered 5-hydroxytryptamine turnover following hemibody X-irradiation in the rat distal colon.

PURPOSE: Acute gastrointestinal responses to ionizing radiation exposure include a role for 5-hydroxytryptamine (5-HT), but it is not known whether involvement of 5-HT persists and contributes to late effects. The aim was to investigate the acute and later effects of lower hemibody irradiation on 5-HT turnover and the biological effect in the rat distal colon. MATERIALS AND METHODS: Rats were exposed to 10 Gy lower hemibody X-radiation. 5-HT and 5-hydroxyindole acetic acid tissue levels were measured in the distal colon along with the serotonin re-uptake transporter and tryptophan hydroxylase mRNA. 5-HT-containing cells and crypt cell numbers were estimated in addition to 5-HT-stimulated short-circuit current responses in isolated mucosa. Studies were performed from 3 days to 3 months post-exposure. RESULTS: During the acute phase, at 3 days post-irradiation, reductions in cell number, tissue resistance, serotonin re-uptake transporter expression and secretory responses to 5-HT were observed. However, at later times when secretory responses were normal, 5-HT tissue levels and enterochromaffin cell numbers were increased. CONCLUSIONS: The results provide evidence that after 10 Gy hemibody irradiation, modifications persist past the acute phase. In particular, 5-HT turnover in the distal colon is altered during a longer period.

Abdominal irradiation increases inflammatory cytokine expression and activates NF-kappaB in rat ileal muscularis layer.

The small bowel is an important dose-limiting organ in abdominal radiotherapy because irradiation can cause acute enteritis that, in turn, leads to progressively reduced motility and finally, in a later phase, to fibrosis. Because these clinical symptoms may be caused by the early stage of an inflammatory process, we characterized the radiation-induced intestinal inflammation in rats. Abdominal gamma-irradiation (10-Gy) induced a cascade of inflammatory events characterized by an early (6 h after exposure) increase in IL-1beta, TNF-alpha, and IL-6 mRNA levels in the rat ileal muscularis layer. IL-8 [a cytokine-induced neutrophil chemoattractant (CINC)] mRNA appeared later (at 3 days). The expression of TGF-beta (a profibrotic cytokine) was higher in irradiated than control tissue at day 1, whereas IL-10 (an anti-inflammatory cytokine) expression vanished completely. Despite strong IL-1ra expression, the IL-1ra/IL-1beta ratio, which is an indicator of inflammatory balance, was -41% at day 1 in irradiated compared with control tissue. The nuclear transcription factors NF-kappaB and activator protein-1 (AP-1) govern transcription of these genes, directly or indirectly. Although expression of the subunits of NF-kappaB (p65, p50) and AP-1 (c-fos, c-jun) did not increase, irradiation caused a rapid and persistent translocation of p65 and p50. An imbalance between proinflammatory and anti-inflammatory mediators may contribute to perpetuating intestinal inflammation, thus making it chronic.

Towards a human repertoire of monocytic lysosomal proteins.

The lysosomal compartment of human monocytic cells has never been investigated by a proteomic approach. By a combination of one-dimensional (1-D) and two-dimensional (2-D) gel electrophoresis, protein identification by N-terminal sequencing, matrix assisted laser desorption/ionization-mass spectrometry (MALDI-MS) peptide mass fingerprinting and tandem mass spectrometry (MS/MS) peptide sequence analysis, we initiated an exhaustive study of the human lyososomal proteome, which aims at establishing a 2-D reference map of human soluble lyososomal proteins. Human monocytic U937 cells were induced to secrete lysosomal soluble hydrolases by addition of NH4Cl in the culture medium. Since lysosomal soluble proteins are characterized by the presence of mannose-6-phosphate, they were purified on an affinity support bearing mannose-6-phosphate receptor. Analysis of the purified fraction led to the preliminary identification of fifteen proteins, among which twelve are well-known lysosomal hydrolases, one is assumed to be lysosomal on the basis of sequence homology to cysteine proteinases of the papain family, and two (leukocystatin and the human cellular repressor of E1A-stimulated genes) are described here for the first time as mannose-6-phosphate-containing proteins.

Organic solvent extraction as a versatile procedure to identify hydrophobic chloroplast membrane proteins.

As a complementary approach to genome projects, proteomic analyses have been set up to identify new gene products. One of the major challenges in proteomics concerns membrane proteins, especially the minor ones. A procedure based on the differential extraction of membrane proteins in chloroform/methanol mixtures, was tested on the two different chloroplast membrane systems: envolope and thylakoid membranes. Combining the use of classical sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and mass spectrometry analyses, this procedure enabled identification of hydrophobic proteins. The propensity of hydrophobic proteins to partition in chloroform/methanol mixtures was directly correlated with the number of amino acid residues/number of putative transmembrane regions (Res/TM ratio). Regardless of the particular case of some lipid-interacting proteins, chloroform/methanol extractions allowed enrichment of hydrophobic proteins and exclusion of hydrophilic proteins from both membrane systems, thus demonstrating the versatility of the procedure.

CD135 (Flk2/Flt3) expression by human thymocytes delineates a possible role of FLT3-ligand in T-cell precursor proliferation and differentiation.

The expression of the Flk2/Flt3 molecule (CD135), the receptor for Flt3 ligand (FL), was investigated in the human thymus. Results showed that there is a high level of expression of CD135 by thymocyte populations, especially by intrathymic T-cell precursor populations. As these results suggested a role for FL in the regulation of thymic T-cell precursor differentiation and/or proliferation, we used an in vitro model of thymic stromal cell cultures in order to delineate the activity of FL on human CD7(high)CD3-CD4-CD8- triple negative intrathymic T-cell precursors. Results showed that FL, either alone or in combination with stem cell factor (SCF) induced the proliferation of CD7(high) precursors, but to a lower extent than interleukin-7 (IL-7) or IL-7 + SCF, used as positive controls. In the presence of FL + SCF, CD7(high) cells developed mainly towards a CD11b+ phenotype whereas IL-7 + SCF preferentially induce a CD3+TcRgammadelta+CD8+ phenotype. Taken together, these data suggest that FL may play a role in inducing the proliferation of CD7(high) human intrathymic T-cell precursors, but also in the induction of a myeloid differentiation pathway within the human thymus.

Transplantation of gene-modified human bone marrow stromal cells into mouse-human bone chimeras.

Transplantation of BM stromal cells engineered to secrete therapeutic factors could represent a treatment for a large array of hematologic disorders. The aim of this study was to evaluate the susceptibility of human BM stromal cell precursors to retroviral gene transfer, then the ability of those to be transplanted in vivo. We have transduced a recombinant retrovirus encoding the mouse CD2 antigen into STRO-1+ cells selected from adult and fetal BM. Gene-modified stromal cells were injected intravenously into NOD-SCID mice engrafted previously with pieces of human fetal hematopoietic bone. Using nested PCR, transgenic human cells were detected both in the marrow of human bone grafts and in the BM, liver, and spleen of host mice 7 weeks after grafting. These data indicate that BM stromal progenitor cells are targets for retrovirus-mediated gene transfer and can home to hematopoietic tissues on engraftment through the bloodstream of nonconditioned hosts.

Antibody-mediated endocytosis of G250 tumor-associated antigen allows targeted gene transfer to human renal cell carcinoma in vitro.

Specific gene transfer into targeted tumor cells remains a critical issue for the development of systemic gene therapy protocols. With this end in view, we have tested the possibility of selectively directing genes to tumor cells through the recognition of tumor-associated antigens (TAA). This was approached in vitro on four human renal cell carcinoma (RCC) lines by means of the highly specific mouse G250 monoclonal antibody (mAb) chemically conjugated to a plasmid DNA conveying a reporter activity. This mAb directed to a TAA that is present on 95% of primary RCCs and on 60% of metastatic human RCCs was extensively characterized, including during clinical trials. Epifluorescence microscopy analysis indicated that upon specific binding to G250 TAA, G250 mAb alone or conjugated to plasmid DNA was internalized by an active endocytic process and colocalized with the transferrin concentrated in the late recycling perinuclear compartment. We also observed that both unconjugated G250 mAb or G250 mAb conjugated to plasmid DNA remained in the perinuclear region of the cells for > or = 20 hours and were not rapidly translocated to lysosomes or recycled to the plasma membrane. In contrast, unconjugated plasmid DNA was not internalized. After transfection of G250 TAA-positive RCC lines with G250 mAb conjugated to a plasmid cDNA encoding mouse interleukin-2, a significant and sustained production of mouse interleukin-2 protein was detected from days 5-15 and was abrogated by inhibiting the internalization process. Altogether, our data showed that endocytosis of G250 TAA should be the basis of gene transfer to RCC, suggesting that targeting of TAA capable of internalization may be the basis of new approaches for designing alternative cancer gene therapy procedures.

Characterization of Dictyostelium discoideum cathepsin D.

Previous studies using magnetic purification of Dictyostelium discoideum endocytic vesicles led us to the identification of some major vesicle proteins. Using the same purification procedure, we have now focused our interest on a 44 kDa soluble vesicle protein. Microsequencing of internal peptides and subsequent cloning of the corresponding cDNA identified this protein as the Dictyostelium homolog of mammalian cathepsins D. The only glycosylation detected on Dictyostelium cathepsin D (CatD) is common antigen 1, a cluster of mannose 6-sulfate residues on N-linked oligosaccharide chains. CatD intracellular trafficking has been studied, showing the presence of the protein throughout the entire endocytic pathway. During the differentiation process, the catD gene presents a developmental regulation, which is also observed at the protein level. catD gene disruption does not alter significantly the cell behaviour, either in the vegetative form or the differentiation stage. However, modifications in the SDS-PAGE profiles of proteins bearing common antigen 1 were detected, when comparing parental and catD(-) cells. These modifications point to a possible role of CatD in the maturation of a few Dictyostelium lysosomal proteins.

Functional interaction of the cytoplasmic domain of triadin with the skeletal ryanodine receptor.

Triadin has been shown to co-localize with the ryanodine receptor in the sarcoplasmic reticulum membrane. We show that immunoprecipitation of solubilized sarcoplasmic reticulum membrane with antibodies directed against triadin or ryanodine receptor, leads to the co-immunoprecipitation of ryanodine receptor and triadin. We then investigated the functional importance of the cytoplasmic domain of triadin (residues 1-47) in the control of Ca2+ release from sarcoplasmic reticulum. We show that antibodies directed against a synthetic peptide encompassing residues 2-17, induce a decrease in the rate of Ca2+ release from sarcoplasmic reticulum vesicles as well as a decrease in the open probability of the ryanodine receptor Ca2+ channel incorporated in lipid bilayers. Using surface plasmon resonance spectroscopy, we defined a discrete domain (residues 18-46) of the cytoplasmic part of triadin interacting with the purified ryanodine receptor. This interaction is optimal at low Ca2+ concentration (up to pCa 5) and inhibited by increasing calcium concentration (IC50 of 300 microM). The direct molecular interaction of this triadin domain with the ryanodine receptor was confirmed by overlay assay and shown to induce the inhibition of the Ca2+ channel activity of purified RyR in bilayer. We propose that this interaction plays a critical role in the control, by triadin, of the Ca2+ channel behavior of the ryanodine receptor and therefore may represent an important step in the regulation process of excitation-contraction coupling in skeletal muscle.