Biomedical subjects
Publications and source records attributed to G Breton.
No chromosomal anomaly was found in 15 cases of typical Friedreich's ataxia and three cases of atypical recessive ataxia studied with Q and G banding techniques. No difference between frequency of chromosomes gaps or breakages was noted amongst patients with Friedreich's ataxia and controls.
All clinical laboratory tests carried out in 4 groups of patients with the diagnosis of typical or atypical Friedreich's ataxia have been found to be within the normal range. In this prospective study of 50 patients, a number of findings previously reported to be abnormal in the literature, have not been confirmed.
Our prospective survey of 50 ataxic patients confirms the previous finding of frequent clinical or chemical diabetes in Friedreich's ataxia. Eighteen percent of our typical cases have clinical diabetes and 40% at least an abnormal glucose tolerance curve. However, this finding does not appear to be specific to that form of ataxia. Furthermore, we have shown that most patients with ataxia have normal or low fasting insulin levels, but a hyperinsulinic response to a glucose load.
In our studies, high total bilirubin values in the plasma were noted in cases of Friedreich's ataxia. A bimodal distribution of the values indicated the possible presence of two subgroups of patients. In these kindred, we demonstrated an elevation in unconjugated bilirubin with features similar to those reported in Gilbert's syndrome: normal liver function tests, elevation after fasting and day to day variability. We also report preliminary experiments indicating that bilirubin levels may be taurine dependent. We postulate that the defect could be a secondary component of the ataxic disease, possibly indicating a defect in membrane transport.
A study of amino acids determined by sequential Multi-sample Amino Acid Automatic Analyzer in plasma, urine and cerebrospinal fluid (CSF) in patients with Friedreich's ataxia and control subjects has revealed a number of mathematically significant variations from normal. Of practical physiological importance are the following: a high urinary excretion of alanine with slightly elevated plasma levels; a low plasma and CSF concentration of aspartic acid in the presence of normal urinary values and finally a low CSF concentration of taurine accompanied by normal plasma levels, but elevated urinary output and renal clearance rates. We postulate that the modifications in alanine and aspartic acid are less specific and probably secondary, but there could be a genetic defect in the membrane transport of taurine and the other beta-amino acids in Friedreich's ataxia.
Friedreich's ataxia patients show evidence of an abnormally elevated and prolonged response of pyruvate and lactate to a glucose load, with normal fasting levels. However, ther is a bimodal distribution of this response with high and low pyruvate responders. This trait appears to be determined genetically, However, although in vivo tests suggest low oxidation of pyruvate, we were unable to confirm any in vitro impairment of each of the components of the pyruvate dehydrogenase (PDH) complex. We conclude that the defect is in the metabolic regulation of PDH, probably at the E3 (lipoamide dehydrogenase) step.
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Research in panic disorder (PD) has highlighted a low biological threshold (lactate infusion). Also, several studies have shown neurophysiological changes with PD patients: increased brain perfusion (Stewart), parahypocampal hyper-perfusion (Reiman) and we reported an increased incidence of epileptiform abnormalities. In order to assess neuroanatomical changes we carried out a study with magnetic resonance imaging (MRI) of P.D. as compared to controls. A prospective study with MRI was done with 13 P.D. patients and 10 controls. The inclusion criteria were outpatients with P.D. according to DSM-III criteria. All subjects (patients and controls) were right handed and between 18 and 40 years of age. Usual exclusion criteria were used. A Signa MR machine of 1.5 telsa (General Electric) was used and images in T1, T2 mode were generated. We found a higher percentage of brain atrophy in patients with PD (64%) than with controls (20%) and the differences reached significance (p-.04-Fisher ex. test). Right temporal lobe horn atrophy was the most common finding in P.D. patients. There were no difference between patients and controls for age, sex and weight. We have found anatomical changes in young P.D. patients. Whether this atrophy found with MRI and physiological changes previously reported are related should assessed further. However, our findings support biological factors in the etiology of PD and stimulates the development of better pharmacological treatments.
In 40 patients with ascites, hyperechogenicity of the kidneys was directly proportional to the amount of fluid interposed between the clinically normal kidney and the transducer. The beam-enhancing phenomenon of ascites on renal parenchymal echogenicity should be distinguished from renal disease causing the increase in parenchymal echoes.