Retracted: Evaluation of the incidence of microcracks caused by Mtwo and ProTaper NEXT rotary file systems versus the Self Adjusting File: a scanning electron microscopic study.

The following article from International Endodontic Journal, 'Evaluation of the incidence of microcracks caused by Mtwo and ProTaper NEXT rotary file systems versus the Self Adjusting File: a scanning electron microscopic study' by S. G. Saha, N. Vijaywargiya, S. Dubey, D. Saxena & S. Kala, published online on 24 November 2015 in Wiley Online Library (wileyonlinelibrary.com), has been retracted by agreement between the authors, the journal Editor in Chief, Prof. Paul Dummer, and John Wiley & Sons Ltd. The retraction has been agreed due to the consideration that the SEM methodology used by the authors has the potential to cause cracks and is thus is not suitable for the evaluation of micro-cracks in roots.

Involvement of corticosteroid-like neurosteroids in pentobarbital-induced sleep.

Recent reports have confirmed the involvement of neurosteroids in a number of neurophysiological processes, including sleep, and that these compounds interact with the gamma-aminobutyric acid receptor A complex. As many of the behavioural effects of pentobarbital are as a result of the activity at this complex, we investigated the role of corticosteroid-like neurosteroids in regulation of sleep, using metyrapone as a tool. Metyrapone, a blocker of the enzyme 11 beta-hydroxylase, which is essential for the biosynthesis of corticosteroids, when administered intracerebroventricularly (i.c.v.) at low doses (50-5000 ng) caused a dose-dependent reduction in sleep time induced by pentobarbital. This effect was, however, antagonized by concomitant administration of anti-corticotropin-releasing factor antisera. The present study reveals for the first time that corticosteroid-like neurosteroids might be involved in the regulation of CNS excitability.

Subcommissural organ-Reissner's fiber complex of the teleost Clarias batrachus responds to GABA treatment.

Subcommissural organ (SCO) is a highly specialized ependymal gland located in the roof of the third ventricle. The secretory products of the SCO, which condense to form Reissner's fiber (RF), were recently found to cross-react with the anti-calcitonin antibody. To understand the mechanisms regulating the formation of the RF and the possible function of these discrete structures, we studied the response of the SCO-RF complex to intracranially administered GABA, using immunocytochemical labeling with anti-calcitonin antibody. Although the SCO-RF complex of control fish was intensely immunostained, 1 h after GABA treatment, the ependymal cells revealed partial loss of immunoreactivity; the RF showed occasional loss of immunoreactivity with its diameter increased by about 56% of the control value. Following 2 h of GABA treatment, the SCO revealed dramatic loss of calcitonin-like immunoreactivity from the ependymal cells. The RF showed a dual response in this group, while in some segments the RF appeared conspicuously thick, elsewhere it appeared thin. The mean diameter was, however, not significantly different from the normal. Following 4 h of GABA treatment, while calcitonin-like immunoreactive material made its reappearance in the SCO, the RF diameter was uniformly reduced to about 35% of the control value. The responses by the RF as well as the SCO to intracranially administered GABA were blocked by pretreatment with bicuculline, a GABA(A) receptor antagonist. The results suggest that GABA, acting via GABA(A) receptors, may trigger the release of secretory material from the SCO and induce histomorphological changes in the RF indicative of discharge of stored material.

Beta-endorphin-like immunoreactivity in the forebrain and pituitary of the teleost Clarias batrachus (Linn.).

The organization of beta-endorphin-like immunoreactivity in the olfactory system, forebrain, and pituitary of the teleost Clarias batrachus was investigated. Immunoreactivity was prominently seen in the sensory neurons and basal cells in the olfactory epithelium and in some cells in the periphery and center (granule cells) of the olfactory bulb. Immunoreactive fibers in the olfactory nerve enter the olfactory nerve layer of the olfactory bulb and branch profusely to form tufts organized as spherical neuropils in the glomerular layer. While fascicles of immunoreactive fibers were seen in the medial olfactory tracts, the lateral olfactory tracts showed individual immunoreactive fibers. Immunoreactive fibers in the medial olfactory tract extend into the telencephalon and form terminal fields in discrete telencephalic and preoptic areas; some immunoreactive fibers decussate in the anterior commissure, while others pass into the thalamus. While neurons of the nucleus lateralis tuberis revealed weak immunoreactivity, densely staining somata were seen at discrete sites along the wall of the third ventricle. Although a large population of immunoreactive cells was seen in the pars intermedia of the pituitary gland, few were seen in the rostral pars distalis and proximal pars distalis; immunoreactive fibers were seen throughout the pituitary gland.

FMRFamide-like immunoreactivity in the olfactory system responds to morphine treatment in the teleost Clarias batrachus: involvement of opiate receptors.

In view of the close relationship between the FMRF-related peptides and the central opiate-sensitive system, we investigated the effects of morphine, alone and in combination with naloxone, on the FMRFamide-like immunoreactivity in the olfactory system of the teleost, Clarias batrachus. In the olfactory system of normal and untreated fish, FMRFamide-like immunoreactivity was confined to the ganglion cells and fibers of the terminal nerve; the cells in the olfactory epithelium per se or the olfactory nerve were not immunoreactive. Intensely immunoreactive cells appeared in the olfactory epithelium following 2 h of intracranial morphine administration. FMRFamide-like immunoreactivity also appeared in the olfactory nerve fibers as they ran caudally and arborized in the glomerular layer of the bulb. However, immunoreactivity in the ganglion cells of the terminal nerve and the ensuing fibers was abolished, suggesting the transport/release of the immunoreactive material. Pretreatment with naloxone, a potent opiate receptor antagonist, reversed the effects of morphine, suggesting the involvement of opiate receptors in the regulation of the ganglion cells of the terminal nerve. The results provide initial immunocytochemical evidence in favor of a relationship between the opiates and FMRFamide-containing systems within the framework of the olfactory system.