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Biomedical subjects

R Katz

Publications and source records attributed to R Katz.

At least 379 records · Page 21Linked to original sources

Presynaptic inhibition in humans: a comparison between normal and spastic patients.

During the last 40 years, several studies in man have been devoted to the pathophysiological mechanisms underlying spasticity. Spasticity is characterised by a velocity dependent increase in muscle tone. Many spinal pathways control stretch reflex excitability and a malfunction in any one of them could theoretically produce the exaggeration of the stretch reflex. Delwaide showed that the vibration-induced inhibition of Ia fibres is reduced in spastic patients. However, the relation between a decrease in presynaptic Ia inhibition and the pathophysiology of spasticity has been recently questioned since it was argued that homosynaptic depression (or post-activation depression) also contributes to the vibratory-induced depression of monosynaptic reflexes. This paper is thus devoted to a review of the methods recently developed to study selectively presynaptic Ia inhibition in man and to a reevaluation of the relations between modifications in presynaptic Ia inhibition and spasticity in hemiplegic and spinal spastic patients.

Extremities↗

McArdle's syndrome: the reaction to a fat-rich diet.

The effect of a diet enriched with fats on the muscle performance of a patient with McArdle's syndrome was studied. The tolerance to physical activity was studied during exercise (ergometric examination) and by sustained abduction to 90 degrees of the deltoid muscle, both after a three-day period on a normal diet and after a three-day period on a fat-rich diet. After the first period a woody spasm of the deltoid muscle was found which lasted several days. After a period on fat-rich diet the patient's physical fitness was increased and the recovery period after the acute load was shorter. Moreover, no induration of the deltoid muscle was observed after the sustained abduction to 90 degrees. It is argued that maximal strength is not improved by a fat-rich diet but tolerance to submaximal loads is increased by such treatment and recovery from non-lactate-produced muscle discomfort is hastened.

Adult↗

Relationship between pretreatment electroencephalographic coherence measures and subsequent response to electroconvulsive therapy: a preliminary study.

Quantitative analyses of EEG recordings taken prior to a course of ECT in elderly depressed patients showed that normal anterior interhemispheric coherence in the delta frequency band was associated with more favorable clinical response to ECT, whereas lower coherence values were associated with incomplete therapeutic response. Clinical implications of these findings are discussed.

Aged↗

Optical stylet: an aid to intubation and teaching.

An optical stylet was developed which can be inserted into an endotracheal tube, and the passage through the vocal cords and position of the cuff in the trachea could be controlled visually. It is of great help in difficult intubations in adults and children. It became an invaluable tool in teaching endotracheal intubation by coupling a teaching attachment (beam splitter) to theoptical system. The operator and the second observer (student) can see the actual manipulations simultaneously.

Education, Medical↗

Brain uptake and utilization of fatty acids: recommendations for future research.

A primary goal of the international workshop "Brain Uptake and Utilization of Fatty Acids" was to identify research areas that would benefit from further investigation. The major themes for future research are presented below: (1) Elucidating the role of the developing and mature cerebrovascular endothelium (CVE) in the uptake of fatty acids (FA) into the brain. (2) Clarifying the role of diffusion and receptor-mediated uptake of FAs by various brain cell membranes and protein-mediated shuttling of FAs between the CVE and various brain cells and tissues. (3) Illuminating the mechanisms of intermediate metabolism and the roles of polyunsaturated fatty acids (PUFA) in astrocytes, neurons and oligodendrocytes. Of special interest are the long-chain omega-3 PUFA and their derivatives, such as lipoproteins, phospholipids and plasmalogens, that have been associated with various disease states (such as those listed in [5], below). (4) Elucidating the role of gene expression on long-chain omega-3 PUFA incorporation in membranes and the regulatory role these and other PUFA have on gene expression in the brain. (5) Elucidating the recently identified roles of long-chain omega-3 PUFA in mood disorders, schizophrenia, stroke, peroxisomal biogenesis disorders, Huntington's disease, other neurodegenerative disorders and disorders of oxidative stress. (6) Undertaking placebo-controlled clinical trials to assess the therapeutic potential of omega-3 PUFA in the above disorders. (7) Developing new, and utilizing existing animal models in the above studies. (8) Developing noninvasive imaging and tagging methods for quantifying the migration and distribution of PUFA and their derivatives in the brain. (9) Applying multi-disciplinary collaborations among biophysicists, physiologists and molecular biologists to the resolution of the above.

Animals↗

Brain uptake and utilization of fatty acids: applications to peroxisomal biogenesis diseases.

The brain is rich in diverse fatty acids saturated, monounsaturated and polyunsaturated fatty acids with chain lengths ranging from less than 16 to more than 24 carbons that make up the complex lipids present in this organ. While some fatty acids are derived from endogenous synthesis, others must come from exogenous sources. The mechanism(s) by which fatty acids enter cells has been the subject of much debate. While some investigators argue for a protein-mediated process, others suggest that simple diffusion is sufficient. In the brain, uptake is further complicated by the presence of the blood-brain barrier. Brain fatty acid homeostasis is disturbed in many human disorders, as typified by the peroxisomal biogenesis diseases. A workshop designed to bring together researchers from varied backgrounds to discuss these issues in an open forum was held in March, 2000. In addition to assessing the current state of knowledge, areas requiring additional investigation were identified and recommendations for future research were made. A brief overview of the invited talks is presented here.

Animals↗