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Repetitive Injections (repetitive + injection)

Distribution by Scientific Domains

Medical Sciences	75%

Selected Abstracts

Role of Nitric Oxide in Pentylenetetrazol-Induced Seizures: Age-Dependent Effects in the Immature Rat

EPILEPSIA, Issue 4 2000
Anne Pereira de Vasconcelos
Summary: Purpose: Seizure susceptibility and consequences are highly age dependent. To understand the pathophysiologic mechanisms involved in seizures and their consequences during development, we investigated the role of nitric oxide (NO) in severe pentylenetetrazol (PTZ)-induced seizures in immature rats. Methods: Four cortical electrodes were implanted in 10-day-old (P10) and 21-day-old (P21) rats, and seizures were induced on the following day by repetitive injections of subconvulsive doses of PTZ. The effects of NG -nitro- l -arginine methyl ester (l -NAME; 10 mg/kg) and 7-nitroindazole (7NI; 40 mg/kg), two NO synthase (NOS) inhibitors, and l -arginine (l -arg; 300 mg/kg), the NOS substrate, were evaluated regarding the mean PTZ dose, seizure type and duration, and mortality rate. Results: At P10, the postseizure mortality rate increased from 18,29% for the rats receiving PTZ only to 100% and 89% for the rats receiving l -NAME and 7NI, respectively; whereas l -arg had no effect. Conversely, at P21, NOS inhibitors did not affect the 82,89% mortality rate induced by PTZ alone, whereas l -arg decreased the mortality rate to 29%. In addition, all NO-related drugs increased the duration of ictal activity at P10, whereas at P21, L -arg and L -NAME affected the first seizure type, producing clonic seizures with L -arg and tonic seizures with L -NAME. Conclusions: The relative natural protection of very immature rats (P10) against PTZ-induced deaths could be linked to a high availability of L -arg and, hence, endogenous NO. At P21, the modulation of seizure type by NO-related compounds may be related to the maturation of the brain circuitry, in particular the forebrain, which is involved in the expression of clonic seizures. [source]

The learning process of the hydrolocalization technique performed during ultrasound-guided regional anesthesia

ACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 4 2010
S. BLOC
Background: Because poor echogenicity of the needle remains a safety issue, we decided to analyze the learning process of the hydrolocalization technique (Hloc) performed to continuously identify needle-tip anatomical position during many ultrasound-guided regional anesthesia procedures. Methods: Ten senior anesthesiologists naïve to the Hloc agreed to participate in the study. They were requested to perform 40 out-of-plane (OOP) approach ultrasound-guided axillary blocks (AB) each using the Hloc. The Hloc, which is a needle-tip localization principle, was performed by means of repetitive injections of a small amount of a local anesthetic solution (0.5,1 ml) under an ultrasound beam. Details of the learning process and skill acquisition of the Hloc were derived from the following parameters: the duration of block placement, a measure of the perceived difficulty of needle-tip visualization, a measure of block placement difficulty, and the amount of local anesthetics solution required for the technique. Results: Four hundred ABs were performed. The success rate of an ultrasound-guided AB was 98%. The Hloc was successful in all patients. Skill acquisition over time of the Hloc was associated with a significant reduction of both the duration and the perceived difficulty of ABs placement. Apprenticeship data revealed that 20 blocks were required to successfully place AB within 5 min in most cases using the Hloc. Conclusion: The Hloc performed during the OOP approach of ultrasound-guided regional anesthesia is a simple technique with a relatively short learning process feasible for efficient placement of ABs. [source]

Endotoxin-Induced Myeloid-Derived Suppressor Cells Inhibit Alloimmune Responses via Heme Oxygenase-1

AMERICAN JOURNAL OF TRANSPLANTATION, Issue 9 2009
V. De Wilde
Inflammation and cancer are associated with impairment of T-cell responses by a heterogeneous population of myeloid-derived suppressor cells (MDSCs) coexpressing CD11b and GR-1 antigens. MDSCs have been recently implicated in costimulation blockade-induced transplantation tolerance in rats, which was under the control of inducible NO synthase (iNOS). Herein, we describe CD11b+GR-1+MDSC-compatible cells appearing after repetitive injections of lipopolysaccharide (LPS) using a unique mechanism of suppression. These cells suppressed T-cell proliferation and Th1 and Th2 cytokine production in both mixed lymphocyte reaction and polyclonal stimulation assays. Transfer of CD11b+ cells from LPS-treated mice in untreated recipients significantly prolonged skin allograft survival. They produced large amounts of IL-10 and expressed heme oxygenase-1 (HO-1), a stress-responsive enzyme endowed with immunoregulatory and cytoprotective properties not previously associated with MDSC activity. HO-1 inhibition by the specific inhibitor, SnPP, completely abolished T-cell suppression and IL-10 production. In contrast, neither iNOS nor arginase 1 inhibition did affect suppression. Importantly, HO-1 inhibition before CD11b+ cell transfer prevented the delay of allograft rejection revealing a new MDSC-associated suppressor mechanism relevant for transplantation. [source]

A Metal-Chelating Piezoelectric Sensor Chip for Direct Detection and Oriented Immobilization of PolyHis-Tagged Proteins

BIOTECHNOLOGY PROGRESS, Issue 4 2004
Hsiu-Mei Chen
A metal-chelating piezoelectric (PZ) chip for direct detection and controlled immobilization of polyHis-tagged proteins has been demonstrated. The chip was prepared by covalently binding a hydrogel matrix complex of oxidized dextran and nitrilotriacetic acid (NTA) ligand onto an activated alkanethiol-modified PZ crystal. The resulting chip effectively captured Ni2+ ions onto its NTA surface, as disclosed by the resonant frequency shift of the crystal and an X-ray photoelectron spectroscopy analysis. The real-time frequency analysis revealed that the bare NTA chip was nonfouling, regenerable, and highly reusable during continuous repetitive injections of ion solutions and binding proteins. In addition, the chip displayed good long-term reusability and storage stability. The individual binding studies of a polyHis-tagged glutathione- S -transferase and its native untagged form on various metal-charged chips revealed that Co2+, Cu2+, and Ni2+ ions each had different immobilization ability on the NTA surface, as well as their binding ability and selectivity with the tagged protein. As a result, the tagged protein immobilized on the Ni2+ -charged chip can actively be bound with its antibody and substrate. Further, the quantitative analyses of the tagged protein in crude cell lysate with a single Ni2+ -charged chip and of its substrate with a protein-coated chip were also successfully demonstrated. Therefore, this study initiates the possibilities of oriented, reversible, and universal immobilization of any polyHis-tagged protein and its functional study using a real-time PZ biosensor. [source]