Effects of dexamethasone on central and peripheral ACTH systems in the rat

To investigate the simultaneous effects of dexamethasone on peripheral and central adrenocorticotropic hormone (ACTH) systems, rats were treated with dexamethasone or saline for 4 days. Pituitary, plasma, hypothalamus and cerebrospinal fluid (CSF) were then collected and analyzed for ACTH immunoreactivity. Additionally, hypothalamic tissue extracts were analyzed for corticotropin-releasing hormone (CRH) immunoreactivity. Dexamethasone significantly lowered peripheral levels of ACTH as measured in pituitary and plasma. Hypothalamic ACTH content significantly increased while CSF ACTH significantly decreased with dexamethasone treatment. Hypothalamic CRH concentrations showed a small but statistically insignificant decrease. These results suggest that prolonged exposure to dexamethasone affects central as well as peripheral ACTH activity, corroborate our previous findings in rhesus monkeys of decreased CSF ACTH in response to prolonged dexamethasone treatment, suggest that dexamethasone may inhibit the release of ACTH from hypothalamic neurons into the CSF, and provide evidence that the effect of dexamethasone on pituitary ACTH content is of greater magnitude than its effect on hypothalamic CRH.     

What can be expected from the sub-trigonal injection of phenol in the treatment of idiopathic instability of the bladder?

Sub-trigonal phenol injection ensures a satisfactory response in about 50% of patients with detrusor instability. When oral anticholinergic treatment is poorly tolerated or ineffective, this minimally invasive technique has been found, in our series of 11 patients, to be a useful adjunct, at least temporarily.     

Laminar organization of the main olfactory bulb of Podarcis hispanica: an electron microscopic and Golgi study

In this study, the lamination pattern of the main olfactory bulb (MOB) of P. hispanica has been described using EM and Golgi-impregnation techniques. Six layers could be distinguished from the external surface to the ventricles: olfactory nerve layer (ONL), glomerular layer (GL), external plexiform layer (EPL), mitral layer (ML), internal plexiform layer (IPL), and granular cell layer (GCL). In ONL unmyelinated axonic bundles from the olfactory mucosa are seen. The GL is defined by the presence of terminal ramifications of the mitral primary dendrites and by axonic terminals of the olfactory nerve. The EPL is a dendritic articulation layer between the mitral and granule cells, where a great density of dendrodendritic synaptic contacts has been found. The ML is defined by the large mitral cell somata, and the IPL by myelinated axonic bundles that run rostro-caudally. Finally, the GCL is characterized by the presence of granule cells. Using the Golgi-impregnation method, five different neuronal types have been described. In the glomerular layer, a small cell population is located; these neurons seem the periglomerular cells described in mammals. The second type corresponds to the mitral cell population and the morphological features of these cells resemble to those of mammals. The three remaining types constitute the granule cell population; this population is characterized by a great morphological heterogeneousness. However, these types have been differentiated according to their dendritic tree morphology and location of the cell body. A morphological gradient depending on the distance of cell body for each type to the ependymal layer, has been observed. In EM, four different types of neuronal cell bodies according to their location and ultrastructure have been defined. The laminar organization of the MOB of Podarcis is similar to that in all vertebrates. The results for the fine structure and dendritic tree morphology have revealed a high similarity between these reptiles and mammals.     

Electrophysiologic effects of halothane and quinidine on canine Purkinje fibers: evidence for a synergistic interaction

The authors studied possible interactions between halothane and quinidine on the action potentials of canine Purkinje fibers superfused with Tyrode's solution. Using standard microelectrode techniques and a physiologic pacing rate (2 Hz), halothane in concentrations from 0.5% to 2% decreased the action potential duration to 50% repolarization (ADP50). Total ADP (APD100), in contrast, increased after 1% and 2% halothane. Resting membrane potential (RMP) and action potential amplitude (APamp) increased after 0.5% halothane, but returned to control with higher halothane levels. Conduction time (CT) increased at each halothane level. Pacing at faster (3 Hz) or slower (1 Hz) rates did not markedly alter the effects of halothane. Quinidine 1 X 10(-5)M decreased the phase O upstroke (Vmax) and prolonged APD100 and CT. When halothane was added, RMP and APamp decreased, Vmax decreased further, and APD100 and CT were markedly prolonged. This resulted in conduction block or inexcitability, especially at faster pacing rates (3 Hz). Synergistic interactions between halothane and quinidine were found on RMP, APamp, APD100, and CT. Effects on Vmax, APD50, and action potential duration to 90% repolarization (APD90) were additive. It is concluded that quinidine and halothane act synergistically to decrease action potential amplitude, lower RMP, and prolong conduction. Severe depression of conduction often progressed to conduction block or inexcitability when halothane, 2%, was administered during superfusion with therapeutic concentrations of quinidine.     

The use of the monoclonal antibody Ki-67 in the identification of proliferating cells: application to surgical neuropathology

In order to test its potential application to surgical neuropathology, the monoclonal antibody Ki-67 was used to demonstrate immunohistochemically the proliferating cells in 40 neoplasms of the nervous system. The antibody, which reacts with a nuclear protein expressed in the G1, G2, S, and M phases of the cell cycle, was demonstrated in frozen sections of all lesions. The highest incidence of stained nuclei was found in a metastatic carcinoma (57%). The percentage of stained cells in gliomas was in general agreement with the histologic grade and known biologic behavior of the lesions, ranging from 0.6% in a pilocytic astrocytoma to 12.4% in a glioblastoma multiforme. In the fibrillary astrocytic neoplasms of low cellularity, there were good correlations between the percentages of stained cells and the degrees of nuclear pleomorphism and chromatin density. In meningiomas, schwannomas, and a cerebellar hemangioblastoma, the fractions of labeled nuclei were less than 1%. The percentage of stained cells in pituitary adenomas showed considerable variation among the four cases (0.2-1.5%), the biologic significance of which is unknown. In four of the above cases, Ki-67 staining was performed on air-dried squash preparations with excellent visualization of immunoreactive nuclei. In one case, a hemangioblastoma, no stained nuclei were seen. The results confirm that Ki-67 staining is technically suitable as a diagnostic method, with good correlations between frozen sections and smear preparations. Determination of the replicating cell fraction could become an important additional criterion to predict the biologic behavior of nervous system neoplasms.