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Medical Sciences	40%
Life Sciences	40%

Selected Abstracts

Developmental changes in the BDNF-induced modulation of inhibitory synaptic transmission in the Kölliker,Fuse nucleus of rat

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 12 2007
Miriam Kron
Abstract The Kölliker,Fuse nucleus (KF), part of the pontine respiratory group, is involved in the control of respiratory phase duration, and receives both excitatory and inhibitory afferent input from various other brain regions. There is evidence for developmental changes in the modulation of excitatory inputs to the KF by the neurotrophin brain-derived neurotrophic factor (BDNF). In the present study we investigated if BDNF exerts developmental effects on inhibitory synaptic transmission in the KF. Recordings of inhibitory postsynaptic currents (IPSCs) in KF neurons in a pontine slice preparation revealed general developmental changes. Recording of spontaneous and evoked IPSCs (sIPSCs, eIPSCS) revealed that neonatally the ,-aminobutyric acid (GABA)ergic fraction of IPSCs was predominant, while in later developmental stages glycinergic neurotransmission significantly increased. Bath-application of BDNF significantly reduced sIPSC frequency in all developmental stages, while BDNF-mediated modulation on eIPSCs showed developmental differences. The eIPSCs mean amplitude was uniformly and significantly reduced following BDNF application only in neurons from rats younger than postnatal day 10. At later postnatal stages the response pattern became heterogeneous, and both augmentations and reductions of eIPSC amplitudes occurred. All BDNF effects on eIPSCs and sIPSCs were reversed with the tyrosine kinase receptor-B inhibitor K252a. We conclude that developmental changes in inhibitory neurotransmission, including the BDNF-mediated modulation of eIPSCs, relate to the postnatal maturation of the KF. The changes in BDNF-mediated modulation of IPSCs in the KF may have strong implications for developmental changes in synaptic plasticity and the adaptation of the breathing pattern to afferent inputs. [source]

Effect of Er:YAG laser and EDTAC on the adhesiveness to dentine of different sealers containing calcium hydroxide

INTERNATIONAL ENDODONTIC JOURNAL, Issue 7 2003
F. Picoli
Abstract Aim, To evaluate the effect of 15% EDTAC solution and Er:YAG laser irradiation on the adhesiveness to dentine of root canal sealers containing calcium hydroxide. Methodology, The crowns of 60 maxillary human molars were ground until dentine was exposed. The teeth were divided into three groups of 20 teeth: group I, the dentine surface received no treatment; group II, 15% EDTAC solution was applied to the dentine; group III, the dentine received Er:YAG laser application (11 mm focal distance with perpendicular incidence to dentine surface; 4 Hz frequency; 200 mJ energy; 2.25 W potency; 62 J total energy; 1 min application time). Aluminium cylinders filled with the sealers, Sealer 26, Apexit, Sealapex and CRCS, were then applied to the treated surfaces. Adhesiveness was measured with a universal testing machine, with traction results given in MegaPascals (MPa). These results were submitted to anova tests. Results, Statistical analysis showed significant differences (P < 0.01) amongst adhesiveness values of the sealers and treatments tested. Thus, sealers could be ranked in decreasing adhesiveness values: Sealer 26, CRCS, Apexit, Sealapex. Er:YAG laser irradiation and EDTAC solution application increased adhesiveness values only for Sealer 26 and Apexit. Laser irradiation was superior to EDTAC application only for Sealer 26 adhesiveness values. Conclusions, Er:YAG laser is as efficient as EDTAC solution in increasing adhesiveness of root canal sealers containing calcium hydroxide to human dentine. [source]

Effects of supplementary pollination on cropping success and fruit quality in pistachio

PLANT BREEDING, Issue 5 2002
Y. Vaknin
Abstract The effects of pollen supplementation in pistachio orchards using an electrostatic pollination device were investigated in a 3-year study (1996-98) in San Joaquin Valley, California, USA. Both yield and fruit quality (per cent split fruit) were tested in several experiments. Applying smaller amounts of pollen (1.5 g per tree in early application only in 1996 or 0.5 g in two applications in 1997) resulted in higher yields than with open pollination or supplementary pollination using larger amounts of pollen (1.5 g per tree in four applications in 1996 or 1.0 g in two applications in 1997). Applying 1.0 g pollen in two applications in 1998 resulted in decreased yields compared with open pollination or non-electrostatic pollination. Pollen germinability on the stigma was greatest for open pollination suggesting that overloading the stigmas with pollen in supplementary pollination may not only reduce yield but also increase competition between pollen grains. The per cent split fruit significantly increased only once in 1996. When pollination is a limiting factor, electrostatic pollination of pistachio can increase yield and may even increase fruit quality. However, when pollination is not a limiting factor, electrostatic pollination may even reduce yield. [source]

Monitoring individual compliance in glaucoma patients used to topical therapy

ACTA OPHTHALMOLOGICA, Issue 2007
AM BRON
Purpose: Individual compliance with Brimonidine eye drops was studied in glaucoma patients and ocular hypertensives. Methods: Conventional Brimonidine vials were equipped with a microprocessor-controlled monitoring device capable to record date and time of each eye drop application including ambient temperature. After written informed consent, glaucoma and ocular hypertensive patients used to eye drop therapy were randomly assigned to Brimonidine therapy b.i.d or t.i.d daily for 4 weeks. Results: Twenty six males and fourteen females aged 69 ± 11 years [42-89] were enrolled in this study. According to the monitoring devices all patients were non-compliant with regard to total dose and coverage. Electronic records revealed a mean of 1.5 (range: 1.1-2.0) applications per day for patients assigned to Brimonidine 2x daily with a mean treatment interval of 16.8 hours (range: 12.1-22.2 h). Patients on Brimonidine 3x daily showed a mean rate of 1.9 (range: 1.8-2.7) applications per day and a mean treatment interval of 11.9 h (range: 9.1-13.9 h). One patient discontinued therapy after day 7 (12 applications) and one after day 1 (1 application only). No difference was observed between IOP at baseline and after one month (p=0.16). Conclusions: The monitoring devices permit to detect individual non-compliance with regard to missed doses, non-treatment intervals. Our data confirm the need for larger studies on individual compliance with topical ocular therapy in glaucoma. [source]

Use of a new natural clay to produce poly(methyl methacrylate)-based nanocomposites

POLYMER INTERNATIONAL, Issue 1 2010
Djahida Lerari
Abstract Nanocomposites of poly(methyl methacrylate) (PMMA) filled with 3 wt% of modified natural Algerian clay (AC; montmorillonite type) were prepared by either in situ polymerization of methyl methacrylate initiated by 2,2,-azobisisobutyronitrile or a melt-mixing process with preformed PMMA via twin-screw extrusion. The organo-modification of the AC montmorillonite was achieved by ion exchange of Na+ with octadecyldimethylhydroxyethylammonium bromide. Up to now, this AC montmorillonite has found applications only in the petroleum industry as a rheological additive for drilling muds and in water purification processes; its use as reinforcement in polymer matrices has not been reported yet. The modified clay was characterized using X-ray diffraction (XRD), which showed an important shift of the interlayer spacing after organo-modification. The degree of dispersion of the clay in the polymer matrix and the resulting morphology of nanocomposites were evaluated using XRD and transmission electron microscopy. The resulting intercalated PMMA nanocomposites were analysed using thermogravimetric analysis and differential scanning calorimetry. The glass transition temperature of the nanocomposites was not significantly influenced by the presence of the modified clay while the thermal stability was considerably improved compared to unfilled PMMA. This Algerian natural montmorillonite can serve as reinforcing nanofiller for polymer matrices and is of real interest for the fabrication of nanocomposite materials with improved properties. Copyright © 2009 Society of Chemical Industry [source]