Biomedical subjects
Publications and source records attributed to R Bouchard.
The relative failure of symptomatic therapeutic trials for Alzheimer's disease using non-selective cholinergic agonists brings about the need for longitudinal studies with parallel designs aimed at disease stabilization, using trophic substances or amyloid suppressors.
We studied the efficacy and safety of oral tetrahydroaminoacridine (THA) combined with lecithin in 52 patients with Alzheimer's disease. The maximal tolerated dose of THA (up to 100 mg per day) was determined during an eight-week titration period, after which the tolerated dose of THA or placebo was given during two sequential randomized periods of treatment lasting eight weeks each. Highly purified lecithin (4.7 g per day) was administered during all phases of the study. Efficacy was expressed in terms of scores on the Mini-Mental State (MMS) test, the modified MMS test, the Hierarchic Dementia Scale, the Rapid Disability Rating Scale-II, and the behavioral scale of Reisberg et al. Safety was assessed by careful clinical monitoring as well as serial measurements of liver aminotransferases. Forty-six patients completed the titration period, and 39 completed the double-blind period, during which only the MMS score showed a small but significant increase (P less than 0.05) after four weeks of treatment with THA. Autonomic side effects of THA were common but mild. Reversible elevations of serum aspartate and alanine aminotransferase levels to three or more times the upper limit of normal occurred in 17 percent of patients; most of the patients affected were women. A liver biopsy performed in one patient showed resolving focal liver-cell necrosis. These studies fail to demonstrate a significant clinical benefit of THA given orally in a maximal dose of 100 mg per day over a period of eight weeks in combination with lecithin.
Genetic linkage analysis requires the identification and documentation of large families with many affected members present, preferably in more than one generation. The IMAGE Project has been establishing a population-based Alzheimer disease (AD) registry in the Saguenay - Lac-Saint-Jean region of the Province of Quebec. The population of this region has a well-documented ancestry, with reliable genealogical records (since 1842) computerized by SOREP. We have recently begun to investigate the pedigrees of selected probands (definite, probable and possible) from the IMAGE registry in order to identify informative pedigrees for genetic linkage analysis. Interviews were carried out with close relatives of the probands (at least one informant per sibship) to identify secondary AD cases. The questionnaires used pertain to the accuracy of genealogical records, to family medical history and to a retrospective diagnosis of AD for people with cognitive deficits. By these means, we have documented a large extended pedigree in which a total of 15 individuals with cognitive deficits were ascertained over three generations. Of these cases, 7 are still living and there is autopsy confirmation in another one. Computer simulations using the program SIMLINK revealed that this is a potentially informative family for linkage analysis. Horizontal extension of the pedigree to second cousins of the proband is now being carried out. This will render the family IMAGE/1 even more informative in genetic linkage analysis studies.
Since the discovery of a significant depletion of acetylcholine in discrete areas of the brain of patients affected by Alzheimer's disease, attempts at symptomatic therapy have concentrated on acetylcholine supplementation, an approach that is based upon the efficacy of dopaminergic supplementation therapy for Parkinson's disease. Choline, then lecithin, used orally, failed to improve symptoms but the hypothesis that long-term choline supplementation might stabilize the course of Alzheimer's disease remains to be tested. Nerve growth factor may also offer that possibility. Bethanechol administered intracerebroventricularly did not help when a fixed dose was used but individual titration of more selective muscarinic agonists may prove more effective. In this article we report that tetrahydroaminoacridine (THA), given together with highly concentrated lecithin, appears to bring improvement in cognition and in functional autonomy using the Mini Mental State and the Rapid Disability Rating Scale-2 respectively, without change in behavior as reflected by the Behave-AD. Double-blind cross-over studies are in progress to establish its efficacy. Improvement in study design and means of assessment of cognition, functional autonomy and behavior have been made possible by these drug trials.
Rest potentiation, believed to be due to increased utilization of sarcoplasmic reticular calcium, was converted to rest depression by BAY K 8644 (1 microM). Plateau height and duration of the postrest beat were enhanced by BAY K 8644, suggesting an enhancement of extracellular calcium entry. Caffeine (3 mM) also produced depression at all rest intervals, although to a lesser extent than BAY K 8644. Compared with BAY K 8644, treatment with caffeine resulted in an elevation of plateau amplitude and a shortening of action potential duration. Action potential configuration changes induced by rest were unaltered by caffeine despite reduction in rest potentiation. Caffeine-induced rest depression was associated with an increase in the time to peak tension. This was not observed with BAY K 8644. Treatment with both caffeine (3 mM) and BAY K 8644 (1 microM) greatly prolonged time to peak tension. Action potential duration and plateau height were either maintained or increased. Less rest depression was observed with the combination than with either agent alone. These results suggest that 1) BAY K 8644 and caffeine inhibit rest potentiation by different mechanisms, and 2) caffeine-induced inhibition of calcium uptake by the sarcoplasmic reticulum may enhance the effect of BAY K 8644-induced increase in calcium influx on the contractile apparatus.
The deleterious effect of frost on corn harvested for silage was investigated with 30 lactating Holstein cows fed silages from corn harvested at the milk or dough stage, or after one, two, or five frosts. The fibrous components of the corn plant increased as maturity and dry matter content increased, whereas the mineral content tended to decrease. Dry matter intake and 4% fat-corrected milk increased as maturity of the silage increased up to the silage harvested after two frosts and then declined for the silage harvested after five frosts. Gross energy apparent digestibility decreased from 64.9% for milk stage silage to 60.6% for silage from corn harvested after five frosts. Partitioning of gross energy, nitrogen, calcium, phosphorus, potassium, and magnesium provided similar increasing trends in feed intake, utilization, and milk production from milk stage silage to that harvested after two frosts, then a decline of all measurements occurred with silage harvested after five frosts. Net energy for lactation was calculated for each silage from the observed digestible energy, from a regression equation used by the provincial feed evaluation laboratories, and from a recently published summative equation; the latter method appeared best.
Neurotransmitter replacement therapy in Alzheimer's Disease is currently being attempted using bethanechol chloride (Urecholine) infused intracerebroventricularly with an Infusaid continuous infusion pump. The rationale of this therapy is based on the severe cortical pre-synaptic cholinergic deficit in the presence of relatively normal post-synaptic muscarinic receptor density. Patients are selected on the basis of strict clinical criteria at a functional stage 4 or 5 of Reisberg. A cortical biopsy at the time of pump and catheter implantation confirms the diagnosis by histological and biochemical examination. Pre-operative, post-operative and serial mental status assessments combined with functional ADL assessments monitor changes in behavior. A 6 months double-blind treatment period is done in every patient, who is then free to continue if he has improved on active treatment. This specific study is part of a multi-centre trial. Other therapeutic trials using somatostatin analogs, such as Sandostatin, could then be done. The biological effects of the latter compound are being studied currently in adult Green Vervet monkeys, prior to its use in Alzheimer patients. Furthermore autoradiography of bethanechol and peptides labeled with 14C administered in these animals by intracerebroventricular infusion will allow a better knowledge of their pharmacological site of action.
Seventeen patients with Friedreich's ataxia or spastic ataxia were subjected to an urodynamic evaluation. Fifty-three per cent (53%) of the patients presented with urinary symptoms consisting of urgent micturition and urgency incontinence. Cystometric evaluation showed a lack of inhibition of the detrusor in 7 patients (41%). Abnormal electric hyperactivity of the external sphincter was documented in 6 cases (37.5%) by electromyography. Some hypotheses are presented to explain the etiology of these abnormal findings.
We have observed a markedly decreased formation of hippuric acid after benzoic acid load in patients with typical Friedreich's Ataxia compared to normal control subjects. Since there is evidence for normal or even enhanced tauro-conjugation in the bile of patients with this disease, with a decreased G/T ratio, it is unlikely that co-factor or enzyme concentrations are the cause of this defect. We postulate decreased availability of the enzyme for glycine conjugation either to bile acids in the usual situation or to benzoic acid in the artefactual test condition. This could be due to the enzyme's preference for an increased amount of taurine substrate in the liver. The relationship of this observation to the other biochemical changes observed in Friedreich's Ataxia must still be established.
The plasma distribution of alpha-keto acids was measured in 26 subjects including 8 patients with Friedreich's ataxia, 8 with the recessive spastic ataxia of Charlevoix-Sageunay and 10 healthy volunteers. The groups were matched with regards to age, sex, weight and the study was conducted under standardized dietary intake. The result indicate significant differences in the alpha-keto acids distribution between the groups.
To test the physiological significance in vivo of our previous in vitro finding of reduced valine dehydrogenase (VDH) activity in patients with Friedreich's Ataxia, we subjected ataxic patients and controls to an oral valine load test (1.0g) and measured the levels of branched chain alpha-keto acids in the plasma for 24 hours. We demonstrated a significantly higher peak for a alpha-keto isovaleric acid in Friedreich's Ataxia and a general trend towards higher than control values in all other alpha-keto acids measured, and at all times in the experiment. These changes are compatible with the postulated defect in regulation of the activity of VDH in this illness, but because of their small amplitude, they also indicate that a VDH deficiency is not the genetic defect in Friedreich's Ataxia.
We have studied a large family of which seven members suffer from a progressive disease with onset in the first decade. The first symptoms were gait ataxia and clumsiness in all cases, followed by progressive development of severe distal amyotrophy reminiscent of Charcot-Marie-Tooth disease. In four patients a postural tremor which was relieved by pharmacological agents was also evident in the limbs or head. Cerebellar atrophy was confirmed on CT scan. Motor nerve conduction velocities were in the low normal range, while sensory nerve conduction was markedly decreased. All patients had impaired proprioception and vibration sense. The laboratory investigation revealed a normal CSF protein level and elevated serum bilirubin. The patients reported in this study apparently suffer from an original recessive form of spinal and olivocerebellar degeneration associated with a neuronal form of Charcot-Marie-Tooth disease.
Dynamic muscle function was evaluated in nine patients with Friedreich's ataxia (FA) and eight with autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS). The measurement of torque throughout maximum voluntary isokinetic knee movements was used to quantitatively describe muscle weakness in the ataxic patients. Both FA and ARSACS patients were shown to have decreased dynamic strength in comparison to normal values during knee extension and flexion movements at 30 degrees/s. In the FA patients a lower torque-producing capacity was seen in the older patients. The electromyographic (EMG) activity was recorded in lower extremity muscles during the movements. In the vastus lateralis (VL), deviations from the normal EMG activation pattern were described in both groups of patients. A reduced amplitude in the EMG activity in the medial hamstrings (MH) was seen in the majority of the patients. An index of coactivation was defined by comparing the EMG activity when a muscle lengthened (antagonistic) to the EMG activity when the same muscle shortened (agonistic) during the isokinetic contractions. In comparison to normal values increased coactivation indexes were present in the VL and MH in patients of both groups. The characteristics of dynamic muscle strength and the activation of agonistic and antagonistic muscles described in the present study will provide the basis of evaluation for the effects of therapy in these patients.
Electronystagmographic recordings were made of oculomotor and vestibular function in 11 patients with autosomal recessive spastic ataxia of Charlevoix-Saguenay. All had horizontal gaze nystagmus, marked impairment of smooth ocular pursuit and optokinetic nystagmus, and defective fixation suppression of caloric nystagmus. Many had saccadic dysmetria, but saccade velocity was probably unaffected. Abnormalities pointing to brainstem disturbance were sparse. The findings are thought to indicate mainly diffuse cerebellar disease, with particular involvement of vermis and vestibulo-cerebellum.
Twenty four ataxic patients were investigated with electromyography and nerve conduction studies. They were divided in two groups according to the area they came from, the evolution of the disease, and the clinical signs. Group I patients from the Rimouski area displayed all the clinical and electrophysiological signs of Friedreich's ataxia. Group II comprised patients who presented with a new syndrome known as the autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS). Although the clinical evolution was better in the latter, there were more electromyographic signs of denervation and the motor conduction velocities were slower. Both groups showed identical and important abnormalities in sensory nerve conduction. The results of electrophysiological studies in spastic ataxia have not been reported to our knowledge. They underline the place of spastic ataxia as distinct from Friedreich's ataxia, spastic paraplegia, and the known familial neuropathies.
Electroencephalographic studies have been done in two groups of hereditary ataxia: a group bearing the classical features of Friedreich's ataxia and a group clinically different described as autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS). The qualitative anomalies observed in the two groups were similar and were comparable with the data reported in the literature. However, the main difference between the two groups is the greater incidence of EEG abnormalities in the ARSACS group, which suggests more involvement of the cortical and subcortical structures. This is reinforced by the lower I.Q. performance in the latter patients. Some comments are made about focal EEG findings, behavior and I.Q. In general, EEG was not considered a valuable instrument for diagnosis since no qualitative electric pattern could be identified. With regard to prognosis, EEG cannot be used as a criterion, since there is no relation between the degree of anomalies and the severity of the disease and since EEG does not worsen with the progression of the disease.
Nine cases of Friedreich's ataxia and seven cases of autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS) were submitted to neuroradiological procedures to determine the extent of atrophic processes in the central nervous system. All cases had a computerized cerebral tomography and five were studied with pneumoencephalography. The results show a correlation between the two tests and the comparison between Friedreich's ataxia and ARSACS. In Friedreich's ataxia, the radiological signs are variable and discrete in most of the cases. In ARSACS there are constant signs of cerebellar atrophy almost limited to the superior parts of the vermis and anterior lobes.
We described a cluster of 8 independent sibships of Friedreich's ataxia in the St-Fabien parish of Rimouski and have shown that they are all related within 6 generations. The study of this geographic and genetic isolate permitted the investigation of certain unusual features of the disease such as constant myopia, delayed reaction times to pain, flexor spasms, and a rapid evolution.