Cerebrospinal fluid lactate dehydrogenase in infants with perinatal asphyxia

Cerebrospinal fluid (CSF) lactate dehydrogenase was determined in 19 control infants without asphyxia (Group I), 24 infants with perinatal asphyxia (Group II), and 26 asphyxiated infants with seizures (Group III). Mean birthweights, gestational ages, CSF glucose, protein and red blood cells, and the ages at which the lumbar punctures were performed were not significantly different among the three groups. Mean CSF lactate dehydrogenase was significantly higher in Group III than in Groups I and II. Isoenzyme patterns indicated that the origin of the CSF lactate dehydrogenase was neuronal tissue, or a plasma transudate from increased permeability of the blood-brain barrier. There were 10 deaths due to anoxic encephalopathy in Group III, but none in Groups I or II. Follow-up of survivors at 10 to 30 months of age revealed neurological sequelae in three infants in Group I, two in Group II and five in Group III. Mean CSF lactate dehydrogenase in those with sequelae had not been significantly different from that of normal survivors; however, the mean was significantly higher in infants who died with anoxic encephalopathy compared with normal infants. These data indicate that CSF lactate dehydrogenase is significantly elevated in infants with fatal anoxic brain damage, and suggest that determinations may be of prognostic value in non-fatal cerebral hypoxia.

Glucose-6-phosphate dehydrogenase and its relationship to mental retardation

This study involved 100 patients who were classified as mentally retarded and who were hospitalized under state care. These patients, during the course of their annual physical, were screened for glucose-6-phosphate dehydrogenase (G-6-PD) deficiency. The incidence of G-6-PD deficiency for both black and white subjects (S's) was compared to the incidence of G-6-PD deficiency to be expected in a normal population of each ethnic group. The screening and subsequent statistical analysis of the data indicates that the incidence of G-6-PD is drastically higher among Caucasian males in the atypical population than is to be expected and it is somewhat higher among the atypical Negroes. A chi-square analysis of the observed incidence as compared to the expected incidence produces a difference that is statistically significant to the .001 level for the Caucasians. It is felt that the results of the study, albeit, based on only 100 S's, indicates strongly that there may be a relationship between G-6-PD deficiency and limited mental capacity.

Regional changes in monoamine synthesis in the developing rat brain during hypoxia

4, 14 and 28 days old rats were exposed to hypoxic environment of 6% O2-94% N2 for 30 min. Tyrosine hydroxylase and tryptophan hydroxylase activity was studied in different brain regions (hemispheres, striatum, midbrain and brainstem in vivo by measuring the accumulation of dihydroxyphenylalanine (Dopa) and 5-hydroxytryptophan (5-HTP) respectively, after inhibition of aromatic L-amino acid decarobyxlase with NSD 1015. Tyrosine and tryptophan levels in the different brain regions were measured simultaneously. The tyrosine and tryptophan levels in the various brain parts were generally not influenced during exposure to hypoxia. Tyrosine hydroxylase activity decreased in most areas in the 4 and 14 days old rats, and all brain areas studied in the 28 days old rats. Tryptophan hydroxylase activity decreased markedly in all brain areas at all ages studied. It is concluded that the enzymes tyrosine hydroxylase as well as tryptophan hydroxylase seem to be equally affected during hypoxia in the different brain regions studied.

Experimental stroke in gerbils: effect on translation and transcription

The effect of cerebral ischemia on polypeptide synthesis with isolated microsomes and DNA-dependent RNA polymerase activity with isolated nuclei was investigated by occlusion of right common carotid artery of gerbils. There was a prompt decline of microsomal polypeptide synthesis already at 30 min after occlusion of the artery, and at 4--5 h the specific radioactivity (dpm per microgram protein) was 50% of the control value. At 24 h, when the animals were only slightly responsive to external stimuli, the specific radioactivity of ischemic brain was only 20% of the control value. DNA-dependent RNA polymerase activity was unaffected for 1 h, and clear suppression did not appear until 3 h after occlusion. However, the extent of suppression was similar between polypeptide synthesis and RNA polymerase activity beyond 3 h after occlusion. Although more selective vulnerability of polypeptide synthesis thus exists in cerebral ischemia, the difference between two biochemical processes was not as striking as seen in cerebral anoxia. Focal progression of cerebral ischemia to diffuse infarction in gerbils was suggested as a possible explanation for the disparity in comparison to the diffuse effect in cerebral anoxia along with the difference in the magnitude of acidosis and depletion of energy reserve.

[Subcellular reaction to cerebral hypoxia]

Compensatory-adaptive reaction of the brain to hypoxia depends on destructive and reparative processes developing in neuronal and glial elements. A drastic tension and reconstruction of the energy apparatus--mitochondria occurs, as well as reversible disturbances in informative connections between the nucleus and cytoplasm and between nerve fibers and synapses. As a result, structural-functional activity of organells decreases along with changes in metabolic processes. Destructive processes in oligodendroglia, at all stages of the experiment, are more pronounced than in neurons. Preliminary injection of hydroxybutyric acid to the animals preserves the cellular energy potential under hypoxia, that is evident from the lack of severe alterations in mitochondria and other organells. Mechanisms of the adaptive-compensatory reaction in cortical neurons under hypoxia are connected with tension and reconstruction of all organells of the brain cellular elements and with biochemical shifts of lactate dehydrogenase enzymes.

[Cerebral lactate dehydrogenase isoenzymes in different hypoxic conditions]

Spectrum of LDH isozymes and their activity were compared in animal brain tissue under circulatory and hypoxic forms of hypoxia. Dynamics and manifestation of alterations observed correlated primarily with the type of oxygen deficiency as well as with its severity and length of action. Development of oxygen deficiency in brain tissue was accompanied by increase in total LDH activity and by elevation in content of M-subunits, typical for "anaerobic" spectrum of LDH isozymes, with simultaneous decrease in amount of H-subunits.

[Activity of enzymes of tricarboxylic and pentose-phosphate cycles in dog brain with myocardial infarction]

Under conditions of experimental myocardium infarction caused in dogs by ligation of the anterior descending branch of the left coronary artery, the activity of alpha-ketoglutarate dehydrogenase and succinate dehydrogenase in mitochondria of the cortex, cerebellum and medulla ablongata lowers most intensively on the first and fifth day after the appearance of acute myocardium infarction. Activation of the most important enzymes of the pentose-phosphate cycle (glucose-6-phosphate dehydrogenase and transketolase) which is clearly pronounced on the fifth day is observed in the mentioned sections. In the authors' opinions the above changes in the activity of the enzymes are due to the brain hypoxia which may be the main reason of disturbance in the function of the central nervous system under this disease.

Neurotransmitter-related enzymes and indices of hypoxia in senile dementia and other abiotrophies

Fifty-six brains from middle-aged and elderly normal as well as demented subjects and patients with provisional clinical diagnosis of other neurological and psychiatric diseases were assessed histologically. On this basis the specimens were classified into 14 diagnostic groups. A survey of potential indices of specific neurons has been carried out on these brains in which neurotransmitter-related enzymes, gamma-GTP (a potential index of capillaries) and specific proteins have been determined in up to 20 brain regions. In addition, the agonal state has been tentatively assessed by examining the post-mortem states of the circulatory and respiratory systems. CAT and gamma-GTP activities and the concentration of a soluble neuronal-type protein (neuronin S-5) were found to be relatively unaffected by the agonal state. When cases of senile dementia were compared to controls (matched with respect to the cause of death) the activity of CAT (the potential index of cholinergic neurons) appears to be reduced in the cerebral cortex. This is a preliminary finding, although a correlation was indicated between CAT activity and 'senile' morphological changes, the activity was markedly reduced in only 3 brains. However, despite inconsistencies in the literature (Karczmar, 1975) at least one pharmacological study on humans appears to show that the cholinergic system may be involved in age-related memory degeneration (Drachman and Leavitt, 1974). Cholinergic neurons may be abnormal in the other abiotrophies examined (Huntington's chorea, motor neuron disease and mixed vascular and senile dementia). gamma-GTP and neuronin S-5 (identical in most respects to the soluble acidic neuronal protein 14-3-2 of antigen alpha) were not reduced in senile dementia. The activities of brain decarboxylase (GAD and AAD) and the concentration of another soluble acidic brain protein (neuronin S-6) appear to be affected by the agonal state. This is remarkable because GAD and, in particular, neuronin S6, are relatively unaffected by post-mortem autolysis. As judged by the state of the extraneural systems which regulated the blood and oxygen supply to the brain it appears that terminal 'cerebral hypoxia' is responsible for the depletion of these brain constituents. This effect appears to be particularly marked in deep grey matter. In non-demented patients that die of bronchopneumonia, the areas of the cortex which are depleted in neuronin S-6 are consistent with the pattern of the 'selective vulnerability' of the cortex to hypoxia, suggesting that the terminal state can also affect the neocortex. If so, then this is particularly relevant to studies on senile dementia, for the effect of the terminal bronchopneumonia that so often occurs in these patients (and in patients with other abiotrophies) may be exacerbated by a terminal reduction in cerebral blood flow...