Impaired Reflex Research Articles

α-METHYL-p-TYROSINE IN THE MANAGEMENT OF PHÆOCHROMOCYTOMA

α-methyl- p-tyrosine (α-M.T.) was given to two patients with dopamine-producing malignant phæochromocytoma for 10 and 5 months. The excretion of catecholamine metabolites was greatly reduced with good control of symptoms. One patient developed a florid tremor of the trunk which is provisionally ascribed to α-M.T. Both patients had impairment of circulatory reflexes with postural hypotension. This was incapacitating in case 1 but was corrected by α-M.T. Hypovolæmia was excluded as the cause of postural hypotension. A third patient with benign phæochromocytoma was prepared for operation with α-M.T. which reduced the excretion of catecholamine metabolites almost to normal but did not prevent serious hypertension during operation.

Abnormal response to Valsalva maneuver in diabetics: relation to autonomic neuropathy.

Changes in heart rate on performing the Valsalva maneuver can easily be monitored with an EKG and a modified sphygmomanometer. Observations have been made on twenty-four diabetics and their matched controls. Impairment of cardiovascular reflexes demonstrated by this technic correlates well with the presence of other complications of diabetes, especially neuropathy. Impairment of response increases exponentially with duration of the disease but not with age. Assessment of the degree of autonomic nervous involvement in diabetic patients is of assistance in their management. The procedure employed has proved satisfactory in gaining necessary information rapidly with easily available apparatus.

Impairment of muscle stretch reflexes in tick paralysis.

Experiments with tick-paralyzed dogs and woodchucks have shown impairment of stretch reflexes in addition to partial paralysis at the neuromuscular junction. Stretch reflexes disappear very early during paralysis, whereas nociceptive reflexes do not appear to be directly affected. The early incoordination and the ascending nature of the paralysis may be related to impairment of stretch reflex pathways.

The Viability of Chrysemys picta Submerged at Various Temperatures

The Viability of Chrysemys picta Submerged at Various Temperatures

Vascular lesions affecting the visual pathways.

There is no better means of acquiring an understanding of the subject of neuro-ophthalmology than by firsthand examination of pathologic specimens. For the ophthalmologist it is a most enlightening experience to see the great frequency with which sections of the brain contain lesions that affect, in a variety of interesting ways, the visual pathways. The autopsy material on which this discussion is based was selected by me from a large number of brain sections inspected at the neuropathology conferences conducted by Dr. J. M. Nielsen, of Los Angeles. The present discussion will deal primarily with involvement of the visual pathways through lesions in the temporal isthmus and in the occipital lobes. When the ophthalmologist is confronted with a cerebral defect producing a homonymous hemianopia without optic atrophy or impairment of the pupillary light reflex, he knows that the lesion is situated somewhere posterior to the lateral geniculate bodies. But for

Reflex venomotor activity in normal persons and in patients with postural hypotension.

Reflex venomotor activity has been observed and measured in normal subjects by means of the pressures developed within isolated segments of superficial veins. Strong contractions are caused by the Valsalva maneuver, tilting, cold, exercise, and hyperventilation. After the Valsalva and after tilting there is a brief elevation of central venous pressure. Pulmonary vascular pressures are also increased after the Valsalva. This is taken to indicate a widespread venoconstriction with central shifting of blood. Persons with postural hypotension show little or no segment or central venous pressure response to these stimuli, indicating impaired reflex venomotor activity.

Pupillary Abnormalities in Schizophrenia and during Muscular Effort

The pupils of a normal subject are generally described as equal, reacting by constriction or dilatation to various stimuli. Inequality of the pupils as an isolated finding is said to be relatively common, but impairment of the light reflex, especially in conjunction with pupillary inequality, is held to be strongly indicative, if not pathognomonic, of organic disease of the nervous system. An exception is the “tonic pupil,” for whose abnormally protracted reactions to light and accommodation an organic lesion has not yet been demonstrated. However, impairment of the light reflex is known to occur in subjects in whom there is no evidence of organic nervous disorder. These abnormalities of the light reflex have attracted little attention in this country, and are ignored almost entirely in text-books of neurology and psychiatry. Redlich (1908) made the important observation that muscular exertion might lead to dilatation of the pupil with impairment of the light reflex. Levine and Schilder (1942), in an extensive investigation of this phenomenon, concluded that muscular effort would produce dilatation and impairment of the light reflex in any pupil which initially retained its response to light, and would accentuate a pre-existing abnormality or bring out a latent tendency to impairment of the light reflex. Westphal (1907) first described the pupillary abnormality in catatonic schizophrenia to which the term “catatonic pupil” has been applied. This abnormality consists of pupillary dilatation with impairment of the light reflex, and is usually bilateral. The reactivity to light may vary from moment to moment, or from day to day; or pupillary rigidity may persist for a considerable time, with transient periods of brisk reactivity. Estimates of the frequency of the “catatonic pupil” vary remarkably—from 54 per cent. (Schilder and Parker, 1931) to 3.4 per cent. (Reichmann, 1913). Apparently a higher incidence has been found where repeated examinations have been carried out on the same subjects, but proper comparison is impossible, as the technique of examination has not been detailed by any of the authors.

ALCOHOL AND THE PEDESTRIAN IN TRAFFIC ACCIDENTS

From time to time, publications have appeared on the effect of alcohol on the driving efficiency of operators of motor vehicles. Attempts have been made to correlate the amount of alcohol in the blood, urine or expired air of drivers in traffic accidents and to determine the lowest quantity of the intoxicant in blood, urine and expired air above which it would be reasonably safe to infer that an impairment of reactions and reflexes would occur. Among the observers who have studied this problem are Schwarz,1Heise,2Carlson,3Naville and Rosselet,4Turner5and Selesnick.6The Committee on Tests for Intoxication of the National Safety Council7has recommended that all persons having a level of alcohol in the blood above 0.15 per cent by weight are sufficiently impaired to be unsafe drivers. With the exception of work by Gerber,8who found a blood

The action of the venom of sepedon hæmachates of South Africa

The venom used was an extract from the dried venom glands of the Sepedon hæmachates . Its minimum lethal dose by subcutaneous injection per kilogramme was found to be: for the frog, 0·0012 gramme; for the rabbit, 0·001 gramme; for the rat, 0·0016 gramme; for the car, 0·015 gramme; for the pigeon, 0·0033 gramme; and, by intravenous injection, for the rabbit, 0·00055 gramme. In the case of all these animals, the venom primarily and with greatest intensity affects the respiration. Respiratory paralysis is the cause of death in mammals and in birds; in frogs, the respiratory movements are early paralysed, but death occurs after several days from gradual failure of the circulation. Other conspicuous effects produced by lethal doses in mammals are drowsiness, ataxia, impairment of reflexes, and fall of temperature. In frogs, the venom produces diminution of reflex excitability, motor paralysis, and progressive increase in weight due to œdema.