The morphological correlates of X- and Y-like retinal ganglion cells in the retina of monkeys

Summary The morphology of the ganglion cells of the monkey's retina was revealed by filling the cells with horseradish peroxidase from their cut axons in the optic nerve. This procedure gave much more consistent results than the Golgi method, was much quicker and filled dendrites just as extensively. Quantitative measures of the dendritic tree of two types of ganglion cell, P and P, suggest that they correspond to the physiologically defined Y- and X-cells, respectively.Supported by MRC grant G971/397/B     

The action of CNS drugs on an isolated sympathetic nerve preparation of rabbit.

The effect of some centrally active drugs on the transmission of nerve impulses through the isolated cervical sympathetic nerve and superior cervical ganglion of the rabbit has been studied by recording both preganglionic and ganglionic responses to single square wave stimuli. Chlorpromazine, trifluoperazine and haloperidol have a greater axonal depressant action than the known local anaesthetics procaine and xylocaine. Chlordiazepoxide and diazepam are similar in local anaesthetic potency to procaine while meprobamate and sodium pentobarbitone possess only slight axonal depressant properties. Meprobamate, sodium pentobarbitone and possibly diazepam have ganglion blocking properties while procaine, chlorpromazine, trifluoperazine, haloperidol and chlordiazepoxide reduce the ganglion potential by virtue of their preganglionic action.     

Effect of depolarizing agents on the adenosine-3′,5′-monophosphate content of the bovine superior cervical ganglion

Summary The cAMP content of the bovine superior cervical ganglion increases rapidly when the tissue is incubated in media containing high concentrations of potassium and theophylline. This effect of high K⁺ is mimicked by Rb⁺, Cs⁺ and NH₄ ⁺. The depolarizing substances veratridine and ouabain also cause an increase in the concentration of ganglionic cAMP; the effect of ouabain develops more slowly than that of veratridine. Tetracaine, in high concentrations, reduces the response to potassium, whereas it reduces the response to veratridine at much lower concentrations. Tetrodotoxin, at a concentration that barely affects the response to potassium, prevents the response to veratridine.Some of the results of this study were presented at the 1975 Spring Meeting of the Swiss Pharmacological Society.     

Studies of the mechanisms involved in the production of stress and stress-atropine ulcers in rats

The mechanism of the production of gastric ulcers induced in atropinized rats under stress was investigated and compared with that of stress-induced ulcers (S-ulcer). The etiology of the stress-atropine ulcer (A-ulcer) was found to be mainly due to the participation of adrenergic nerves since the ulceration was inhibited by ganglion blockers, adrenergic blockers, and reserpine, though vagotomy also inhibited the formation of A-ulcer. On the other hand, S-ulcer was inhibited by certain nervous system depressants, ganglion blockres, vagotomy and atropine; therefore, a certrally mediated cholinergic factor was suggested to be the main factor in the ulceration.     

Ganglion blocking properties of some bispyridinium soman antagonists.

Various doses of several bispyridinium compounds (HS-6, HI-6, HGG-12, HGG-42, and SAD-128) known to protect animals against the irreversible cholinesterase inhibitor soman were examined to determine their effects on the cardiovascular and respiratory system of cats. Although the potency varied considerably all of the compounds tested lowered the blood pressure, which appeared to be the result of ganglion blocking properties as determined by their reduction of the pressor response to dimethylphenylpiperazinium and the blockage of the contraction of the preganglionically stimulated cat nictitating membrane. Some of the compounds caused cessation of respiration at much lower doses than others but did so at doses greater than those causing ganglion blockage.     

Subthreshold membrane potential oscillations of type A neurons in injured DRG

An abundance of subthreshold membrane potential oscillations (SMPOs) at resting potential was observed in the neurons of chronically compressed dorsal root ganglia (DRG) using intracellular recording in vivo. Out of 386 neurons, 63 type A neurons displayed SMPOs. Three types of SMPOs were distinguished based on their characterizations of oscillation: (1) A regular pattern of SMPO emerged consistently with a mean frequency of 86 Hz and mean amplitudes of 3.3 mV. (2) A spindle-like pattern of SMPO was denominated by a spindle alteration of its amplitude. (3) An irregular pattern of SMPO had no rule on its change of amplitude and frequency. Compared with normal DRG neurons and injured DRG neurons but without SMPO, the injured DRG neurons with SMPO had the lowest spike rheobase, in accordance with the detection of spike accommodation. No significant differences among the three groups can be found in either membrane potential or input resistance. Further observation showed that the spontaneous discharge of hyperexcitable neurons usually occurred on the depolarizing phase of oscillations. In addition, the regular pattern of SMPO was based on the period and integer multiple patterns of spontaneous discharges. The spindle-like pattern of SMPO contributed to spontaneous bursting discharge. The irregular pattern of SMPO had a striking relation with irregular spontaneous discharge. The results show that neurons with SMPO in injured DRG have a higher excitability than those without SMPO, and that the SMPO underlie the patterns of spontaneous discharges, suggesting that SMPO is the basic electrophysiological change of hyperexcitable neurons.     

The length of Henle fibers in the human retina and a model of ganglion receptive field density in the visual field

An experimental study of lateral displacement of ganglion cells (GCs) from foveal cones in six human retinas is reported. At 406-675 microm in length, as measured in radially oriented cross-sections, Henle fibers are substantially longer than previously reported. However, a new theoretical model indicates that the discrepancies in these reports are mainly due to meridional differences. The model takes into account the effects of optical degradation and peripheral ON/OFF asymmetry and predicts a central GC:cone ratio of 2.24:1. It provides estimates of cumulative counts and GC receptive field density at 0 degrees -30 degrees along the principal meridians of the visual field.     

Comparative Study of Recurrence and Complications Using Various Sclerosants by Single Dart Technique in Treatment of Ganglion Cysts

Ganglion cysts are tense,smooth,fluctuant,cystic and transilluminant swellings. They are commonly found on the dorsum of the wrist, at the scapholunate articulation and may involve volar wrist, tendon sheaths and even inter phalangeal joints. This study aims to compare the efficacy and the recurrence rates with triamcinolone, hyaluronidase and sodium tetradecyl sulphate,using the single dart technique. This prospective observational study was conducted on patients who presented to the general surgery outpatient department of our institute with ganglion cysts of wrist between January 2010 and August 2011 (20 months). A total of 180 patients were included in this study. The difference in the recurrence rates after sclerotherapy for ganglion cysts is statistically not significant between triamcinolone and hyaluronidase regimens as Z (P1–P2) = 1.70, p > 0.05 but the difference in the recurrence rates after sclerotherapy for ganglion cysts is statistically significant between triamcinolone and sodium tetradecyl sulphate regimens as Z (P1–P2) = 3.34, p < 0.05 . Chi-square value −10.33 (2 ° of freedom), p = 0.00571987 (significant at 5 % level). Intralesional injection of triamcinolone by single dart technique, therefore, may be considered as a simple, safe, cost effective, convenient, less invasive alternative to surgical excision of wrist ganglion cysts.     

Compression neuropathy of the common peroneal nerve caused by an intraosseous ganglion cyst of fibula

We present a case of a compression neuropathy of the common peroneal nerve caused by an intraosseous Ganglion cyst of fibula.