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Biomedical subjects

L Gauthier

Publications and source records attributed to L Gauthier.

At least 91 records · Page 5Linked to original sources
PubMed1987

Current status of levodopa therapy in idiopathic Parkinson's disease.

Levodopa is currently used at all stages of Parkinson's disease, particularly from Stage 3 onward. Most patients start levodopa within four years of the onset of disease, earlier in the akineto-rigid patients (average delay of 2.1 years) than in those where resting tremor predominates (average delay of 3.4 years). Advanced age (greater than 80) is no deterrent to the use of levodopa if required. Wearing off is most noticeable in Stage 3 or after 10 years of therapy with levodopa. An inverse correlation was found between age and wearing off, suggesting a marked sensitivity of younger patients to levodopa. Future studies on the use of dopamine agonists should thus be stratified according to age.

Adult↗
PubMed1987

Detection of mutagenicity in drinking water using a micronucleus test in newt larvae (Pleurodeles waltl).

We have previously described a micronucleus test using erythrocytes from larvae of the urodele amphibians Pleurodeles waltl (pleurodele) and Ambystoma mexicanum (axolotl). The test is based on a comparison of the levels of micronucleated erythrocytes in blood smears from larvae reared in water containing a clastogen, with the levels from larvae reared in purified water. Using larvae from the pleurodele, we have employed this test to evaluate mutagenic activity in drinking water. Groups of larvae were reared in tap water, while control groups were reared in tap water which had been filtered over sand and active carbon to remove micropollutants. Seven separate tests carried out between October 1985 and May 1986 all gave positive results of varying degree depending on the time of year. This test is therefore able to detect clastogens in normal drinking water. It could be used for quality control of drinking water during the various stages in the treatment of raw water without any requirement for prior extraction or concentration of micropollutants.

Animals↗
PubMed1987

The phosphoenolpyruvate: sugar phosphotransferase system of Streptococcus salivarius. Identification of a IIIman protein.

A double-spontaneous mutant resistant to the growth inhibitory effect of alpha-methylglucoside and 2-deoxyglucose was isolated from Streptococcus salivarius. This mutant strain, called alpha S3L11, did not grow on mannose and grew poorly on 5 mM fructose and 5 mM glucose. Isolated membranes of strain alpha S3L11 were unable to catalyse the phosphoenolpyruvate-dependent phosphorylation of mannose in the presence of purified enzyme I and HPr. Addition of dialysed membrane-free cellular extract of the wild-type strain to the reaction medium restored the activity. The factor that restored the phosphoenolpyruvate-mannose phosphotransferase activity to membranes of strain alpha S3L11 was called IIIman. This factor was partially purified from the wild-type strain by DEAE-cellulose chromatography, DEAE-TSK chromatography, and molecular seiving on a column of Ultrogel AcA 34. This partially purified preparation also enhanced the phosphoenolpyruvate-dependent phosphorylation of glucose, fructose, and 2-deoxyglucose in strain alpha S3L11.

Bacterial Proteins↗
PubMed1987

The benefits of group occupational therapy for patients with Parkinson's disease.

The medical treatment of idiopathic Parkinson's disease has improved the quality of life and increased survival of patients with Parkinson's disease. However, as the illness progresses, impairments in daily living activities occur. A clinical trial for a group rehabilitation program was initiated to maintain the functional status of these patients. The research protocol consisted of a pretreatment evaluation, random assignment to experimental or control groups, and posttreatment evaluations after therapy, at 6 months and at 1 year. The results showed that the subjects of the treated experimental group maintained their functional status after 1 year, demonstrated a significant decrease of bradykinesia, and perceived a significant improvement in their psychological well-being. This study confirms the value of an occupational therapy group approach and its benefits to the functional independence, to the improvement of physical and motor symptoms, and to the quality of life of persons with Parkinson's disease.

Activities of Daily Living↗
PubMed1986

Pointing with left vs right hand in left visual field neglect.

The authors report the detection performances of three subjects with unilateral left visual neglect as they were submitted to a closed-loop manual pointing task in the reaching field. Results show, for all three subjects, better detection performances when manual pointing was executed with the left hand--i.e. contralateral to the lesion--than when made with the right hand. Given that, for both hands, signal detection conditions were the same, these results are discussed according to: other studies having showed changes in the expression of neglect as induced by changes in the nature or the strategy of the task; the concept of an indissociable sensorimotor central processing; and one of the models put forward to account for unilateral spatial neglect which includes a motor representation.

Aged↗
PubMed1986

Transmitter-replacement therapy in Alzheimer's disease using intracerebroventricular infusions of receptor agonists.

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.

Alzheimer Disease↗
PubMed1986

Effect of chronic exposure to an acidified environment on the urophysis of the brook trout, Salvelinus fontinalis.

The activity of the caudal neurosecretory system including its neurohemal organ, the urophysis, was assessed in six populations of brook trout (Salvelinus fontinalis)--three from acidified lakes and three from nonacidified lakes (Laurentides Parc, Québec). The acidified lakes were characterized by low pH (mean annual value around 5.5), poor buffering capacity and low conductivity. The activity of the caudal neurosecretory cells was evaluated by morphometry (cell and nuclear sizes). The urophysial content of the neuropeptide urotensin II was measured by isolated trout rectum bioassay. Fish from acidified lakes showed markedly larger cell and nuclear sizes and a lower content of urotensin II than fish from nonacidified lakes. An acidified environment appears to stimulate the synthetic activity of caudal neurosecretory neurons and promote release of urotensin II from the urophysis. This modified endocrine activity in brook trout may reflect adjustment to adverse external ionic conditions.

Animals↗
PubMed1984

Isolation of a novel protein involved in the transport of fructose by an inducible phosphoenolpyruvate fructose phosphotransferase system in Streptococcus mutans.

Fructose transport in Streptococcus mutans LG-1 is mediated by at least two distinct phosphoenolpyruvate fructose phosphotransferase systems. One system is constitutive and consists of membrane components enzyme II as well as enzyme I and heat-stable protein. The other system is inducible and requires, in addition to enzyme I and heat-stable protein, a soluble substrate-specific protein for catalytic activity. This protein factor, designated IIIfru, was purified by DEAE-cellulose chromatography, hydroxylapatite chromatography, molecular sieving on Sephadex G-75, and preparative electrophoresis. The purified preparation showed only one protein band, with a molecular weight of 12,600, on sodium dodecyl sulfate-urea-polyacrylamide gel electrophoresis, on gel electrophoresis with the discontinuous buffer Tris-glycine, and after electrofocusing in gel (pI congruent to 3.7). The molecular weight of the native protein determined by gel filtration at 4 degrees C was 51,000. Immunodiffusion experiments performed with immunoglobulins prepared against the purified IIIfru from S. mutans LG-1 suggested that other S. mutans strains possessed a IIIfru. No precipitin bands, however, were detected with extracts from S. salivarius, S. sanguis, S. lactis, S. faecalis, Staphylococcus aureus, Bacillus subtilis, Lactobacillus casei, and Escherichia coli.

Biological Transport, Active↗
PubMed1981

Contralateral hindlimb responses to cutaneous stimulation during locomotion in high decerebrate cats.

High intensity stimuli of the skin were delivered to one hindlimb in various parts of the step cycle of decerebrate cats walking on a treadmill. Whereas the stimulated limb always flexes after the stimulation there is, in the contralateral limb, a crossed flexion response during swing or a crossed extension response during stance. The frequency distribution of the responses in contralateral flexor or extensor muscles peaks at around the onset of the respective locomotor bursts although responses can be evoked before and after that onset. In certain periods of the cycle, largely corresponding to the transition from flexor or extensor activity and vice versa, the responses can occur in either muscles. The long latencies of crossed responses are similar to that of the ipsilateral responses so that both occur approximately at the same time. The amplitude and duration of crossed responses vary according to the phase of the walking cycle. The types of responses and the overall changes in the step cycles suggest that crossed extension responses mainly serve to sustain the increased weight to the contralateral side during ipsilateral flexion whereas crossed flexion responses appear well studied to rapidly rephase the contralateral limb step cycle to that of the ipsilateral limb which is markedly perturbed by the flexion response elicited during its stance phase.

Animals↗
PubMed1981

Stimulus--response relationships during locomotion.

Crossed hind limb responses to high intensity stimulation of the superficial peroneal nerve in the cat were studied under various conditions. In precollicularly decerebrate cats walking on a treadmill, the same stimulus train evokes a crossed extension response during the contralateral stance phase and a crossed flexion response during the contralateral swing phase. In acute spinal cats (Th 13) injected with clonidine, a similar stimulus train can evoke a crossed extension response when the limb is manually placed in flexion and a crossed flexion response when the limb is positioned in extension. During "fictive" locomotion, induced in spinal paralyzed cats by nialamide an L-DOPA, the same stimulus may increase the amplitude and (or) the duration of crossed flexor or crossed extensor activity (in-phase responses). In some instances in these preparations, the crossed responses may be out-of-phase with the central rhythm. It is concluded that crossed hind limb responses during locomotion are selected by both central and peripheral mechanisms.

Animals↗
PubMed1980

An analysis of mechanisms controlling the reversal of crossed spinal reflexes.

In acute spinal cats injected with clonidine, a noxious stimulation applied to a hindlimb may evoke in the other hindlimb an extension or a flexion response depending on whether it is respectively flexed or extended passively at the time of stimulation. The contribution of various afferents in the control of such reflex reversal was investigated. After denervation of joints, reflex reversal could still be found. Reflex reversal could be obtained in a pair of antagonist muscles whose distal tendons were cut to prevent length changes during manipulations of the whole limb. This suggests that the response in either the flexor of the extensor of one muscle pair can appear without stretch signals originating from the pair itself and can be determined by the state of stretch of other muscles acting at the same or other joints. When the whole limb was practically denervated except for one muscle pair responses were found only in the extensor muscle indicating that stretch signals from that pair alone were not sufficient to reverse the reflex pattern. After complete rhizotomy, strong responses were also observed only in extensor muscles. These results indicate that crossed extensor responses are not evoked because of interactions with afferent impulses related to the position of the limb. On the other hand, when afferents are intact and the limb extended, crossed extension can be blocked and replaced by crossed flexion. Evidence has been obtained suggesting that the stretch of flexor muscles might indeed change the pattern of crossed extension to a pattern of crossed flexion. These findings are discussed in the context of a purposeful role in posture and locomotion.

Afferent Pathways↗
PubMedDate not supplied

Development of a functional measure for persons with Alzheimer's disease: the disability assessment for dementia.

OBJECTIVES: This article describes the development of an assessment of functional disability for use with proxy-respondents of community-dwelling persons who have Alzheimer's disease as well as a study testing its reliability. METHOD: Panels composed of health care professionals and caregivers of persons with Alzheimer's disease were used to develop the Disability Assessment for Dementia (DAD). Fifty-nine caregivers participated in the refinement of the content and the testing of reliability. RESULTS: The DAD includes 40 items: 17 related to basic self-care and 23 to instrumental activities of daily living. It demonstrated a high degree of internal consistency (Cronbach's alpha = .96) and excellent interrater (N = 31, ICC = .95) and test-retest (N = 45, ICC = .96) reliability. In addition, it was found not to have gender bias. CONCLUSION: This instrument may help clinicians and caregivers of the population with Alzheimer's disease make decisions regarding the choice of suitable interventions.

Activities of Daily Living↗