Action of d-tubocurarine chloride on the central nervous system of the cat

A systematic review on guanitoxin: General characteristics and ecological risks

Guanitoxin (GNT) is a potent cyanotoxin, with a relatively low number of publications (n = 51) compared to other cyanotoxins. Among the published studies, 35 % were on the effect of the toxin in animals, mainly in rodents and in vitro testing, followed by studies that identified species of cyanobacteria that produce GNT in aquatic systems and consequently accidental poisoning in wild and domestic animals (27 %). Studies that developed or tested methods for identifying the molecule, based on colorimetric and analytical techniques, represented 14 %, while 8 % were on GNT biosynthesis. Review articles and chemical isolation (6 %) and on the stability of the molecule (4 %) were the topics with the lowest number of publications. The results show the occurrence of GNT was identified mainly in eutrophic environments with a higher incidence in the American continent. Chemical characteristics of the molecule, such as short half-life in the environment, instability in solutions with alkaline pH values, temperature >23 °C, added to the lack of an analytical standard, are factors that make it difficult to identify and quantify it. However, GNT monitoring can be performed using LC-MS-MRM methods or genes specific to the newly discovered molecule.

Parkinson's Disease Master Regulators on Substantia Nigra and Frontal Cortex and Their Use for Drug Repositioning

Parkinson's disease (PD) is among the most prevalent neurodegenerative diseases. Available evidences support the view of PD as a complex disease, being the outcome of interactions between genetic and environmental factors. In face of diagnosis and therapy challenges, and the elusive PD etiology, the use of alternative methodological approaches for the elucidation of the disease pathophysiological mechanisms and proposal of novel potential therapeutic interventions has become increasingly necessary. In the present study, we first reconstructed the transcriptional regulatory networks (TN), centered on transcription factors (TF), of two brain regions affected in PD, the substantia nigra pars compacta (SNc) and the frontal cortex (FCtx). Then, we used case-control studies data from these regions to identify TFs working as master regulators (MR) of the disease, based on region-specific TNs. Twenty-nine regulatory units enriched with differentially expressed genes were identified for the SNc, and twenty for the FCtx, all of which were considered MR candidates for PD. Three consensus MR candidates were found for SNc and FCtx, namely ATF2, SLC30A9, and ZFP69B. In order to search for novel potential therapeutic interventions, we used these consensus MR candidate signatures as input to the Connectivity Map (CMap), a computational drug repositioning webtool. This analysis resulted in the identification of four drugs that reverse the expression pattern of all three MR consensus simultaneously, benperidol, harmaline, tubocurarine chloride, and vorinostat, thus suggested as novel potential PD therapeutic interventions.

Electrophysiological correlates of the behavioral effects of tubocurarine in conscious cats

The effects of tubocurarine on behavior, electrical activity, and auditory evoked potentials were studied in restrained conscious cats. Tubocurarine hydrochloride (doses of 0.05--1 micrograms intraventricularly) produced various central stimulatory effects characterized by EEG desynchronization, decrease in both low (7--9 Hz) and high (10--14 Hz) alpha waves, and decrease in the amplitude and area of the surface positive (P1) wave of auditory evoked potentials. Concomitant with the alterations in brain electrical activity tubocurarine hydrochloride produced generalized behavioral arousal phenomena and the cats became restless and exhibited miaowing and increased movement of the head and ears. Almost all parameters except behavior showed a distinct dose-response relationship. A correlation between the behavioral effects and the EEG analog was thus demonstrated.

Sleep induced by small doses of tubocurarine injected into cerebral ventricles of dog

In unanaesthetized dogs, sleep with the typical sleep pattern in the E.E.G. was produced with (+)-tubocurarine when injected in a small dose (500 ng) into, or perfused in low concentration (100 ng/ml) through the cerebral ventricles.

The effect of (+)-tubocurarine chloride and of acute hypotension on electrocortical activity of the cat

1. The effects of I.V. injection of tubocurarine (3 mg/kg) and of acute hypotension upon electrocortical activity of cats under sodium pentobarbitone were analysed. Technical artifacts associated with changes in brain volume were minimized.2. Initially, the superficial cortical response was reduced by tubocurarine either insignificantly or by 34% or less. Cats bled before injection of tubocurarine showed initially a similar reduction but, occasionally, a severe delayed reduction was found. Any fall in the superficial cortical response started during the secondary rise in B.P., many seconds after the B.P. had reached its lowest initial level. By contrast, spontaneous electrocortical activity was reduced approximately when the peak initial fall of B.P. occurred and it started to recover during the secondary rise in B.P. Reduction of the superficial cortical response could still be elicited after spindling had been suppressed by deep barbiturate anaesthesia. The initial thalamocortical afferent component in somatosensory area I, which was evoked by dorsal column stimulation, was less reduced by injection of tubocurarine than were the post-synaptic positive-negative components.3. The depressant effects of injected tubocurarine upon the superficial cortical response and spindle activity were approximated by rapid arterial bleeding.4. The superficial cortical response was reduced following virtual arrest of the cerebral circulation by acute exsanguination or by acute oil embolization. Such reduction most likely does not depend on systemic transport of inhibitory substances to the brain.5. After injection of tubocurarine the rate of outflow from the superior sagittal sinus was variably reduced during the initial fall in B.P., and often showed a variable, secondary increase. A net deficit in cerebral blood flow was usually present during the period of 80 sec after injection.6. The variability in the effects of injected tubocurarine upon electrocortical activity is attributed to the variability of the net deficit in cerebral blood flow.

Discussion on operative removal and plastic repair in cases of carcinoma of the hypopharynx and upper oesophagus

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