Joseph F. Fazekas

Cerebral metabolism in hepatic insufficiency

S TUDIES dealing with neurologic disturbances associated with hepatic insufficiency have been confined chiefly to attempts at identifying the neurotoxic substance or substances responsible for the condition. For the most part, attention has been directed to the concentration of ammonia and other nitrogenous or sulfur-containing compounds in the arteriallP3 and cerebral venous blood.4 It is believed that these substances may alter the activity of certain enzyme complexes concerned with intermediate cerebral metabolism.4 In the present study, cerebral hemodynamics and oxygen utilization of patients with varying degrees of neurologic dysfunction associated with hepatic insufficiency were investigated to determine whether or not changes in the functions mentioned could be correlated with alterations in blood ammonia and pyruvate levels or with electroencephalographic activity.

Influence of age and vascular disease on cerebral hemodynamics and metabolism

F the 250 cc. of oxygen consumed per minute by the average-sized man, approximately 50 cc. are utilized by the brain to meet its metabolic demands. Since the brain is largely an aerobic organ, it depends completely upon its circulation for a constant supply of oxygen. It has been estimated that approximately 15 per cent of the total cardiac output is diverted to the brain.’ The high metabolic activity of the cerebral cells and their extreme dependence upon the circulating oxygen makes them unusually susceptible to ischemia of even short duration, those cells with the highest metabolic requirements being most vulnerable.’ In addition to oxygen the cerebral cells are dependent upon their circulation for other substances essential for their metabolic activity. The oxygen consumed by the brain is for the most part utilized for the oxidation of glucose. Since the carbohydrate stores of the brain are inadequate to support its oxidative needs for any appreciable time,3 glucose must also be constantly extracted from the cerebral circulation. Various vitamins and minerals are recognized as essential components of various cofactors necessary for the oxidation of glucose.? These and undoubtedly many other equally essential substances are made available to the cerebral cells via their circulation. In acute situations in which the cerebral circulation is markedly impaired (locally or generally) it is the lack of oxygen that is primarily responsible for the cellular deterioration that rapidly ensues since its turnover rate is greater than that of the other substances extracted from the cerebral circulation. Any organ so dependent on its circulation for its energy supplies must have compensatory mechanisms to protect it against fluctuations in the rate of its blood flow if it is to function efficiently. If the rate of cerebral blood flow is reduced, the extraction of glucose, oxygen and other substances from the arterial blood traversing the brain may be greatly increased. Under normal conditions the cerebral arteriovenous oxygen difference is approximately 7 volumes

Effect of Metrazol Convulsions on Brain Metabolism.

The wide use of metrazol in the treatment of schizophrenia has made it advisable to study the physiological changes produced by metrazol convulsions. 1 Twelve observations were made on 7 patients with schizophrenia. As seen in Table I, 7 samples of blood were collected from the femoral artery during various stages of the convulsions, 4 pairs of samples were collected simultaneously by 2 observers from the femoral artery and internal jugular vein immediately after the seizure had ceased, as was one additional sample of arterial blood. Breathing was greatly diminished during the convulsions and this was reflected in the analyses of the arterial blood, which disclosed a retention of CO2 as well as a diminished O2 content. Even during the first part of the seizure, as seen in Wi, 9/13, the O2 content was diminished so that the Hb saturation was reduced from a theoretical normal of 95% to 84%. As the convulsions progress, the Hb saturation continues to fall so that towards the end of the seizure the saturation of Hb may be below 50% (M., 9/7). During these convulsions the patients face is at first a dark red color. When the convulsion is completed, the anoxemia is evidenced by a leaden cyanosis, Neyertheless, as soon as unimpeded breathing is reëstablished the Hb saturation, though still reduced, is found rapidly rising towards a normal value (last 5 observations of Table I). The anoxemia, as well as the severe muscular effort, combine to increase blood lactic acid and blood sugar. These convulsions, grand mal in character, cause a temporary but marked depression of cerebral functions as evidenced by amnesia, confusion, disorientation, and the elicitation of various abnormal reflexes, such as the Babinski and ankle clonus.

Apparatus for continuous blood-pressure observation.

IN the course of a series of investigations concerning human cerebral hemodynamics a relatively inexpensive, compact apparatus was improvised for continuous observation of the mean arterial blood p...

Cerebral hemodynamics and metabolism in mental deficiency

DISTURBA~-CES in the function of the central nervous system may or may not be associated with alterations in total cerebral blood flow or oxygen consumption. Even those conditions which can be attributed to disorders of cerebral circulation or metabolism may not necessarily be attended by demonstrable characteristic changes in these values. Moreover, there is a large group of so-called “functional” brain disturbances in which there is at present no evidence of either cerebral circulatory or metabolic dysfunction. The present study was instituted to determine whether there was any obvious defect in cerebral hemodynamics or oxygen utilization in subjects classified as mongoloid and in a second group of subjects with nonspecific mental deficiency.

Effects of Cyanide and Iodoacetate on Survival Period of Infant Rats.

Summary The prolonged survival period of infant rats, despite inhibition of the cytochrome-oxidase system with sodium cyanide, demonstrates the function of an anaerobic source of energy. The rapid death after the injection of iodoacetic acid and exposure to an atmosphere of nitrogen suggests the anaerobic conversion of carbohydrate to lactic acid as the source of this energy.

Prognostic Uncertainties in Cerebral Vascular Disease

Excerpt A previous communication reported the results of a correlative study undertaken to compare aortocranial and intracerebral angiographic findings with clinical impressions derived from neurol...

Cerebral Vascular Disease Current Problems of Etiology, Diagnosis, and Treatment

IN CEREBRAL vascular disease, difficulties in pathogenesis, diagnosis, and treatment are at present the rule rather than the exception. This discomforting situation is due to our rather limited knowledge concerning the etiology and pathogenesis of vascular disease in general, to the relative inaccessibility of the human brain, and to the resultant paucity of rational therapeutic modalities. It is the purpose of this discussion to review some of the more pressing problems related to cerebral vascular disease.

Effect of Hypothermia on Cerebral Metabolism

Summary Nine dogs, subjected to hypothermia, suffered a decreased cerebral metabolism as indicated by a smaller A:V difference despite a slower blood flow.

Effect of Sodium Chloride Therapy on Oestrous Cycle and Hypophysis of Bilaterally Suprarenalectomized Rats

Conclusion Sodium chloride therapy in suprarenalectoniized rats during our period of oliservation was effective not only in prolonging life hut also in restoring normal hypophyseal-ovarian activity in 55% of the cases.