Inequality of the direct and consensual light reflexes in normal subjects

Anisocoria in darkness and during reflex responses to unilateral light stimulation was studied in 150 normal subjects with television pupillometry. It was commonly found that the direct light reaction of the stimulation eye exceeded the consensual reaction of the other eye. This light-induced anisocoria, termed 'contraction anisocoria', had a mean value of 0.075 mm or 6.1 % of light reflex amplitude. The measurement showed a high degree of repeatability in 20 subjects who were tested on two occasions a year apart. It occurred in the presence and absence of prior dark adaptation and increased proportionally with reflex amplitude as the intensity of the stimulating light was raised. IT IS CONCLUDED THAT, CONTRARY TO PREVIOUS OPINION, A SMALL DEGREE OF CONTRACTION ANISOCORIA IS NORMAL.

Comparison of the pupillary, refractive, and hypotensive effects of Ocusert-40 and pilocarpine eyedrops in the treatment of chronic simple glaucoma

Twelve patients with chronic simple glaucoma were treated for 1 week with Ocusert-40, and the effects on the pupil, intraocular pressure, and refraction were measured. A comparison was made with the effects of pilocarpine eyedrop therapy in 8 of these patients. Both forms of pilocarpine treatment gave satisfactory control of intraocular pressure and both constricted the pupil to a similar degree shortly after initiation of treatment. During the week on Ocusert-40 the pupils redilated, so that 54% of the initial miosis remained after 7 days' wear. There was, however, considerable variability in the pupillary sensitivity to Ocusert-40 within and between eyes, and it is suggested that this may have been partly due to variable release rates of pilocarpine. Only minor decreases in visual acuity and refraction resulted from pilocarpine in either form. Seven of the 12 patients rejected Ocusert-40 because of discomfort or inability to retain the device.

Changes in the human light reflex as a measure of the anticholinergic effects of drugs. A comparison with other measures

Single oral doses of atropine, nortriptyline, procyclidine and lactose dummy were administered double-blind to eight healthy young subjects in a balanced, crossover study. Television pupillometry was used to measure the anticholinergic effects of these drugs on the pupil diameter in darkness and the reflex response to light flashes. The sensitivity of this method was compared with conventional autonomic function tests, viz. salivary secretion, radial pulse, forearm sweat gland activity and distance to visual near point. Visual analogue scales were used to obtain subjective measures of sedative drug effects. The expected inhibition of parasympathetic activity was found in most instances with two exceptions: firstly, that nortriptyline failed to affect the pupil despite causing a tachycardia and secondly, that procyclidine gave a bradycardia. The results are discussed with reference to the possible advantages of television pupillometry over conventional pupil measurement in the detection of anticholinergic drug effects.

Dynamics of the light reflex and the influence of age on the human pupil measured by television pupillometry [proceedings]

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Ocular and cardiovascular effects of local and systemic pindolol

Ocular and cardiovascular effects of topical and intravenous pindolol have been studied in a balanced cross-0ver double-blind trial in 6 healthy volunteers. When applied to 1 eye pindolol lowered intraocular pressure in both the treated and untreated eyes with only minimal reduction in resting pupil diameter and light reflex response. The concentration in plasma was much lower and inhibiton of exercise tachycardia about half that when the same dose was administered intravenously. The findings suggest that beta-adrenoceptor blocking drugs should not be used in the treatment of glaucoma in patients who also suffer from heart failure.

Differential effects of tryptophan on glucose synthesis in rats and guinea pigs

1. Tryptophan inhibition of gluconeogenesis in isolated rat liver cells is characterized by a 20 min lag period before linear rates of glucose output are attained. 2. Half-maximal inhibition of gluconeogenesis in isolated rat hepatocytes is produced by approx. 0.1 mM-tryptophan. 3. Tryptophan inhibits gluconeogenesis from all substrates giving rise to oxaloacetate, but stimulates glycerol-fuelled glucose production. 4. Gluconeogenesis in guinea-pig hepatocytes is insensitive to tryptophan. 5. Changes in metabolite concentrations in rat liver cells are consistent with a locus of inhibition at the step catalysed by phosphoenolpyruvate carboxykinase. 6. Inhibition of gluconeogenesis persists in cells from rats pretreated with tryptophan in vivo. 7. Tryptophan has no effect on urea production from alanine, but decreases [1-14C]palmitate oxidation to 14CO2 and is associated with an increased [hydroxybutyrate]/[acetoacetate] ratio. 8. These results are discussed with reference to the control of gluconeogenesis in various species.

Observations on the joints of the hand

Thirty-two hands (sixty-eighty years) were dissected to study configuration and spatial setting of the articular surfaces of the joints of the thumb in order to note the features which are associated with deviation, torsion and rotatory movements. Four varieties of the trapezial surface were encountered in the carpometacarpal joint: saddle-shaped, triangular, ovoid and semicylindrical. The last exhibited marked osteoarthrosis with formation of osteophytes.

Pupillary signs in diabetic autonomic neuropathy

Pupillary function was investigated in 36 insulin-dependent diabetics and 36 controls matched for age and sex. About half of the diabetics had evidence of peripheral somatic or autonomic neuropathy, or both. The diabetic patients had abnormally small pupil diameters in the dark and less fluctuation in pupil size (hippus) during continuous illumination than the controls. They also had reduced reflex responses to light flashes of an intensity adjusted for individual retinal sensitivities. The pupillary findings were compared with results of five tests of cardiovascular function and five tests of peripheral sensory and motor nerve function. Almost all the patients with autonomic neuropathy had pupillary signs, which we therefore conclude are a common manifestation of diabetic autonomic neuropathy.

Factors determining the potency of cholinomimetic miotic drugs and their effect upon the light reflex in man

1. Television pupillometry was used to measure the effect of six topically applied cholinomimetic drugs on the resting diameter and light reflex amplitude of the human pupil. Drug potency was obtained from dose response curves. 2. The tertiary amines arecoline, aceclidine and pilocarpine were considerably more effective miotics than the choline esters carbachol, methacholine and acetylcholine. 3. All the drugs which caused miosis also reduced light reflex amplitude proportionally. 4. The in vitro potency of these drugs was also measured on preparations of rabbit iris sphincter and guinea pig ileum. 5. Dose response relationships for pilocarpine in man and in vitro showed evidence of partial agonist activity on the rabbit iris only. 6. A comparison of the in vivo and in vitro results showed that three factors influenced the potency of topically applied miotics: accessibility to the iris; sensitivity to cholinesterase; and cholinoceptor agonist potency.

An increased effect of pilocarpine on the pupil by application of the drug in oil

In healthy volunteers pilocarpine in an oily solution had a greater degree and duration of effect on the pupil than the same amount of drug given in aqueous solution. Blue- and brown-eyed subjects had similar degrees of miosis, but the time taken to reach peak effects was longer with the latter. It can be concluded that eye drops made with an oily solvent may provide an improvement in the treatment of glaucoma with pilocarpine.

Tryptophan and the control of plasma glucose concentrations in the rat

1. Injection of L-tryptophan (750 mg/kg body wt.) led to pronounced hypoglycaemia in fed and 48 h-starved rats. 2. The hypoglycaemic effect is blocked by pretreament with p-chlorophenylalanine, compound MK-486 [Carbidopa: L-alpha-(3,4-dihydroxybenzyl)-alpha-hydrazinopropionic acid monohydrate] or methysergide, and potentiated by pargyline. 3. 5-Hydroxy-L-tryptophan is more potent and induces a more rapid hypoglycaemia than does tryptophan. Other tryptophan metabolites were not associated with hypoglycaemia. 4. Adrenalectomy increases, and acute experimental diabetes strongly decreases, the sensitivity of rats to tryptophan induction of hypoglycaemia. Diabetic animals were also insensitive to 5-hydroxytryptophan. 5. Metabolite concentration changes in the livers from tryptophan-treated 48h-starved and diabetic animals were consistent with a rapid inhibition of gluconeogenesis. This did not correlate with the hypoglycaemic response. 6. Tryptophan treatment was associated with a significant increase in the plasma [beta-hydroxybutyrate]/[acetoacetate] ratio; there were no changes in the plasma concentrations of urea, triacyglycerol, non-esterified fatty acids and glycerol. 7. These observations suggest that the hypoglycaemic action of tryptophan is mediated through formation of intracellular 5-hydroxytryptamine, and is unrelated to the inhibition of gluconeogenesis. It is unlikely that this increased synthesis of 5-hydroxytryptamine involves directly either the adrenal glands or the central nervous system.

Permeability of the liver cell membrane to quinolinate

Quinolinate was taken up by both rat and guinea-pig liver cells. Equilibrium was reached after approx. 20 min with rat cells, but guinea-pig cells had not achieved a steady state after 60 min. There was no evidence to suggest that quinolinate is rapidly metabolized by either species. The concentrations of quinolinate attained in rat and guinea-pig cells after short periods of incubation with 0.5 mM-quinolinate did not inhibit gluconeogenesis. These results raise further doubts as to the mechanism of quinolinate action in liver.