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Biomedical subjects

S Hoyer

Publications and source records attributed to S Hoyer.

At least 109 records · Page 6Linked to original sources
PubMed1985

Validity of the ischemic score in degenerative and vascular dementia and depression in old age.

Thirty six male and 45 female patients (mean age 66 years) suffering from either dementia of Alzheimer type (DAT) or dementia of vascular type (DVT) with comparable severity and suffering from depression in old age were included in the investigation. The study was performed to evaluate the diagnostic value of Ischemic Score, EEG and CT scan of the brain in differentiating dementia types and depression in old age. The patients underwent physical, psychiatric, psychometric, neurological, neurophysiological and CT scan examinations. Clinical diagnosis and diagnosis related to Ischemic Score were consistent in 86% of DAT and in 65% of DVT. Patients suffering from DVT showed significantly higher incidence of distinct Ischemic Scale items than was found in DAT patients. The Ischemic Scale items were found to be of major importance in differentiating vascular dementia from both DAT and depression. However, it was insufficient to distinguish between the latter two. In EEG, general slowing predominated in DAT (68%), and focal disturbances in DVT (71%). Patients with DAT and depression could not be differentiated on the basis of their EEG findings. CT scans of the brain yielded a higher incidence of brain atrophy in patients with DAT (71%) and DVT (70%) as compared to depressive patients (37%). In DAT, ventricular enlargement seems to be rather disease- than age-related. Psychological testing showed abnormalities in attention and memory performance in DAT and DVT to a significantly greater extent as compared to depression. This study demonstrated that the combination of Ischemic Score and EEG was found to be most valid in differentiating DAT from DVT. Additional cranial computerized tomography and the psychological testing of attention and memory were able to confirm the diagnosis of dementia and to differentiate dementia from depression in old age.

Aged↗
PubMed1985

Dementias, psychological tests, and neurotransmitters.

A preliminary investigation was made of data of intelligence quotient, dementia quotients, objective profile analysis of MAWI (Hungarian standardized version of WAIS) in patients suffering from multi infarct, primary degenerative and alcoholic dementia (MID, PDD, Alc. D). Homovanillic acid (HVA) and 5-hydroxyindole acetic acid (5-HIAA) were measured in lumbar cerebrospinal fluid (CSF) from patients with presenile dementia and senile dementia of Alzheimer's type (PDAT and SDAT) and multi infarct dementia. They were compared to controls and to each other. Alcoholic dementia can be differentiated from other types of dementia mainly by the values of verbal and practical quotients (VQ/PQ), Hewson Index 5 and by the objective profile analysis. MID can hardly be differentiated from PDD, but the objective profile analysis can help, mainly subtests 1 and 3 of MAWI. No decrease was found in the concentrations of HVA and 5-HIAA in lumbar CSF of demented patients compared to controls, but there was an elevation in 5-HIAA concentration.

Aged↗
PubMed1984

The effect of naftidrofuryl on cyanide-induced hypoxic damage to glucose and energy metabolism in brain cortex of rats.

Increasing life expectancy increases diseases of old age. Dementia is a highly age-related brain disease in which the metabolic rates of oxygen and glucose are predominantly disturbed. However, related changes in metabolism at the molecular level are rather little known. Knowledge on pharmacotherapeutic modification of the metabolic variations in the brains of demented people is also scanty. Since the vascular type of primary dementia is found to be associated with metabolic variations which resemble that of a cerebral hypoxia, hypoxic brain damage was produced by means of a sublethal dosage of cyanide in two-year-old rats. The cyanide-induced damage in brain metabolism was characterized by an increase of the tricarboxylic acid cycle intermediates succinate, fumarate and malate. This indicates disturbances of NAD+- and FAD+-dependent redox reactions also including pyruvate oxidation. Lactate production was found to be increased, and creatine phosphate formation reduced. Application of 3 mg/kg naftidrofuryl after cyanide damage produced a normalizing effect on the cyanide-induced changes in glucose and energy metabolism of brain cortex of rats. The tentative conclusion may thus be drawn that naftidrofuryl may have a beneficial effect on cyanide-induced hypoxic brain damage. Whether this drug might be useful in other brain hypoxic conditions remains to be investigated.

Animals↗
PubMed1982

[Comparison of the psychopathology with cerebral blood flow and brain metabolism in cerebrovascular insufficiencies].

40 patients (13 males, 27 females) with a mean age of 68 years presented organic brain syndromes of cerebrovascular etiology. They were studied to make an attempt upon the relationship between descriptive symptomatology on one hand and brain-blood-flow and oxidative metabolism on the other. The assessment of psychopathology and additional neurological and physical symptoms and signs was documented by the AMDP-rating scale system, then further computed by cluster analytic procedures. Cerebral blood flow (CBF) was measured by the Bernsmeier and Siemons (1955) modification of the Kety and Schmidt method. The cerebral metabolic rates of oxygen (CMR O2) and carbondioxide (CMR CO2) were determined by gaschromatography, the cerebral metabolic rates of glucose (CMR gluc) and lactate (CMR lac) by standard enzymatic methods. Five symptom-sign clusters were markedly differentiated by size and shape of their profiles. The mean values of the biological data within the clusters found did show different patterns of brain metabolism derangement with increasing tendency to reduced levels and functional decompensation. The latter reflected clinical deterioration in terms of psychopathology: disorders of cognitive functioning as well as psychomotor activity, social and illness behavior, i.e. need for special care. The cerebral metabolism balance worsened resulting in a widespread, gross disturbance of oxidative metabolism with a likely shift to anaerobic glycolysis. The lactate production was extremely heightened. CMR lac may be regarded as a causal quantitative factor significantly linked with pathogenesis, manifestation, and severity of organic brain syndromes.

Adult↗
PubMed1982

The young-adult and normally aged brain. Its blood flow and oxidative metabolism. A review--part I.

Blood flow and oxidative metabolism of the mature and healthy young-adult human brain account for about 20% of the cardiac output and about 20 and 25% of the requirements of oxygen and glucose, respectively, for the whole body. Normal cerebral aging is associated with only smaller reductions in the cerebral metabolic rates of oxygen and glucose while cerebral blood flow would seem to be unchanged. The age-dependent reduction in oxidative brain metabolism may be related to a decline in glycolytic flux due to a diminution of enzyme activities also involving acetylcholine synthesis. This metabolic reduction with age may be tentatively accounted for by a physiologically occurring loss of neurons, dendrites and dendritic spines in distinct brain areas. The mechanisms of autoregulation of cerebral blood flow, of CO2 reactivity of the brain vessels, of arterial hypoxemia on cerebral blood flow and their effects on oxidative and energy metabolism are well documented in young-adult brain. There is, however, no or only minimal information on the responsiveness of the normally aged brain to changes of these important biological parameters controlling and influencing brain blood flow and metabolism.

Adult↗
PubMed1982

The abnormally aged brain. Its blood flow and oxidative metabolism. A review - part II.

The most common brain disease in middle and old age is dementia. Primary dementias comprise degenerative (dementia of Alzheimer type, DAT) and cerebrovascular (dementia of vascular type, DVT) types. These dementia types differ in morphological, clinical, and pathobiochemical terms. In DAT, large amounts of neuritic plaques and neurofibrillary tangles or paired helical filaments, are present throughout the whole brain cortex, but particularly numerous in temporal areas. Here and in hippocampus, the presynaptic cholinergic system seems to be predominantly affected. In DVT, multiple small infarcts are scattered over brain cortex and white matter obviously due to disturbances in cerebral microcirculation. Dementia is closely related to disturbances in brain blood flow and oxidative metabolism. In the beginning of DAT, cerebral blood flow and CMR-oxygen are found to be in normal ranges, but CMR-glucose is reduced. In DVT, cerebral blood flow and CMR-oxygen are also within the normal range, but CMR-glucose is found to be abnormally increased. When dementia symptoms are well developed in DAT, the same relationship between circulation and metabolism are found. Well-developed DVT symptoms seem to be associated with changes in blood flow and metabolism similar to variations after ischemic/anoxic lesions. In the beginning of both dementia types, a close correlation exists between cerebral blood flow and CMR-oxygen, but there is a dissociation from CMR-glucose. In the further course of both dementia types, cerebral blood flow and metabolism run into a final common path of a low functional level. No distinction between the dementia types is possible. In general, severity of dementia symptoms are correlated to the deviation of cerebral blood flow and metabolism from normal. There is much evidence that dementia, i.e. abnormal cerebral aging is different from normal cerebral aging. Dementia is not a form of accelerated cerebral aging.

Aged↗
PubMed1980

[The effects of thiopentone, etomidate and flunitrazepam on cerebral energy metabolism in the rat (author's transl)].

The effect of thiopentone, etomidate and flunitrazepam on cerebral energy metabolism was investigated in the male Wistar rat. Brain cortex was deep-frozen in situ under steady state conditions (normotension, normothermia, normoxia and normocapnia) of a standardized anaesthesia. Anaesthesia with thiopentone led to an decrease in glycolytic flux on the level of the hexokinase and/or phosphofructokinase reaction as well as reduced citric acid cycle intermediates. The brain cortex levels of high-energy phosphates however are unchanged thus indicating an adequate supply of energy for the brain. Similar results were obtained when anaesthesia was induced with etomidate and flunitrazepam. In spite of the fact that flunitrazepam seemed not to influence the phosphofructokinase reaction an equivalent hypnotic dose of each drug led to comparable metabolic effects in the brain cortex.

Anesthesia, Inhalation↗
PubMed1980

Brain oxidative metabolism and blood flow in alcoholic syndromes.

42 alcoholic patients were grouped together according to the symptom-sign clusters derived from original classification variables of AMDP-rating scale system: (1) mild withdrawal, (2) severe withdrawal, (3) Korsakoff's syndrome, and (4) the clinical syndrome of dementia. Groups determined by clusteranalysis were subjected to a discriminant function analysis. Total cerebral blood flow (CBF) and the cerebral metabolic rates of oxygen, carbon dioxide, glucose and lactate were investigated. Patients with mild withdrawal tended to display increased oxygen uptakes reflecting 'pseudonormal' mean values with a wide range of the single data but predominantly elevated over the normal range. In mild withdrawal lactate production showed a tendency to increasing derangement of metabolism. There was much evidence of disturbance of brain oxidative metabolism with progressively decreasing cerebral metabolic rates of glucose, lactate, oxygen, and CBF from mild to severe withdrawal, Korsakoff's syndrome and dementia. Progression of both clinical phenomenology and cerebral dysfunction and/or damage culminates in simplified (reduced, "burnt-out") neuronal functional levels in advanced cases.

Adult↗
PubMed1979

[Influence of combined moderate arterial hypoxaemia and moderate hypovolaemic hypotension on cerebral blood flow and cerebral oxidative and energy metabolism in the dog (author's transl)].

The influence on total cerebral blood flow, cerebral metabolic rates for oxygen, carbon dioxide, glucose, lactate and pyruvate and on cerebral grey matter content of glucose, lactate and pyruvate and high energy phosphate compounds of combined moderate reduction in cerebral perfusion pressure (CPP) and moderate arterial hypoxaemia was studied. Individually arterial hypoxaemia and arterial hypotension of the same degree would neither impair autoregulation of cerebral blood flow nor cerebral oxygen availability. Four groups of 10 dogs each were studied under control conditions (group I), with reduction of CPP to 70 mm Hg (group II), with reduction of paO2 to 45 mm Hg (group III) or with a combination of these degrees of hypotension and hypoxaemia (group IV) after steady states of 30 min duration. Cbf was elevated by 40% in group III (p less than or equal to 0.01), CMRO2 was reduced significantly in group IV (p less than or equal to 0.01, CMR lactate was raised significantly in all three experimental groups (p less than or equal to 0.01). All other data were not significantly different from values in control animals. Cerebral tissue lactate content was elevated significantly in groups II to IV as compared to controls (less than or equal to 0.05); changes in cerebral tissue content of glucose and energy rich phosphate compounds were not statistically significant. From the seemingly normal cerebral blood flow in hypotensive-hypoxaemic dogs it is concluded that autoregulation of cerebral blood flow has become ineffective because of vasodilatation consequent upon arterial hypoxaemia. Reduction of CMRO2 in this group points to metabolic insufficiency and to relative cerebral hypoperfusion, but since changes in cerebral content of high energy phosphate compounds were not significant, severe tissue hypoxia may be excluded. The increase in cerebral tissue lactate content is attributable to increased glycolytic activity known from hypotensive and hypoxaemic states. The present investigation suggests that in patients with hypoxaemia and hypotension, brain function may be endangered by a similarly marked change of circulatory and metabolic parameters.

Animals↗
PubMed1978

Cerebral glucose and energy metabolism, cerebral oxygen consumption, and blood flow in arterial hypoxaemia.

The influence of moderately reduced arterial oxygen tension (aPO2 of about 45 Torr) on the metabolism and the blood flow of the brain was tested in 20 anaesthetized, artificially ventilated normotensive, normocapnic beagle dogs. It is demonstrated that the decrease in systemic oxygen delivery to the brain is countered by an appropriate increase in flow (CBF being 60.3 ml/100 g min at normoxia and 84.5 mg/100 g min in hypoxaemia) which maintained the cerebral oxygen consumption unchanged (CMRO2 3.80 versus 3.32 ml/100 g min). The cortical tissue content of energy-rich phosphates such as ATP, ADP, AMP, and phosphocreatine was also found to be unaltered. Neuropathological examinations excluded any hypoxic cell damage. This reactive vasodilatory reaction of the cerebral vessels is apparently a sensitive regulatory process which protects the brain against marked oxygen lack. However, a normal carbohydrate metabolism is not restored by this cerebrovascular mechanism. For, significantly increased CMRlactate (0.32 versus 1.46 ml/100 g min) indicated raised cerebral glycolysis, and the tissue metabolites of glucose suggested an increased glycolytic flux in the brain. It is concluded that in moderate arterial hypoxaemia, which is not uncommon in clinical practice, cerebral blood flow plays an effective homeostatic role in preventing a disturbance of the energy metabolism of the brain.

Adenine Nucleotides↗