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Biomedical subjects

J Logothetis

Publications and source records attributed to J Logothetis.

At least 19 recordsLinked to original sources
PubMed1993

Algorithmic and heuristic strategies in comprehension of complement clauses by patients with Parkinson's disease.

Language ability in patients with idiopathic Parkinson's disease (PD) and normal control subjects (NC) matched on age, sex, education and socioeconomic status (SES) was investigated. The two groups of subjects were tested on eight sentence types in Greek in the form of main and complement clause with eight matrix verbs. These matrix verbs were ask (ask information), promise (commissive meaning), tell1 (order, command) and tell2 (give information) in sentences with no semantic constraints, and confess, sell, trust and scold in sentences with semantic constraints (implicit causality). The results show that language ability, despite relative preservation is significantly impaired in PD patients as compared to that of NC. More specifically, syntax with semantic constraints was the most effective independent variable to classify PD patients and NC subjects into two distinct groups according to a Logistic Regression Analysis. To restrict the algorithmic process in sentence comprehension, PD patients seem to make use of the minimal distance principle (MDP) and the "experiencer constraint" heuristic strategies. Possible similarities in language behavior between PD patients and aphasics, in general, are suggested.

Aged↗
PubMed1991

Understanding of relational time terms before and after in Parkinsonian patients.

The role of the relational time terms before and after in language comprehension was investigated using patients with Parkinson's disease (PD) and normal controls (NC) in Greek. Results lead to the following four conclusions: (a) Comprehension by PD patients of before and after constructions displaying syntactic, semantic, and cognitive constraints equivalent to those of English is significantly different from that of NC matched on chronological age, sex, education, and socioeconomic status. (b) Before is better understood than after. (c) Syntactic variables, when semantic effects are partialed out, do not affect performance. The same is true of semantic effects when syntactic variables are partialed out. (d) Order of mention of events is a predominant source of errors when syntax and semantics are controlled. The data are discussed in relation both to findings with aphasics and to developmental results on the same time terms.

Aged↗
PubMed1991

Strategies in comprehension of relative clauses by parkinsonian patients.

Twenty patients with Parkinson disease (PD) and twenty normal control subjects (NC) matched on age, sex, education and socio-economic status (SES) were tested for comprehension of four types of relative clauses with complex thematic roles (syntax) and no semantic and pragmatic constraints (reversible) in a sentence-picture matching task. The results show a clear language impairment for PD patients compared to NC. Additional evidence from testing school children in grade 1 (G1) and grade 6 (G6) indicates that G1 children perform similar to PD patients and G6 children perform as high as NC. The overall picture of the findings suggests: (1) PD patients process sentences with complex thematic roles and semantic reversibility on a heuristic and not on an algorithmic basis, a type of behavior assumed to be associated with frontal lobe dysfunction; (2) PD patients display some patterns of language behavior similar to those observed in aphasics. Similarities in language behavior between PD patients and G1 children are discussed with regard to the "regression hypothesis" (Jacobson, 1968).

Aged↗
PubMed1989

Piribedil therapy in Parkinson's disease. Use of the drug in the retard form.

We conducted a 20-week nonblind study to evaluate the efficacy of piribedil in 30 patients with idiopathic Parkinson's disease (PD). Prior to the study 17 of these patients were under L-Dopa treatment alone or in combination with anticholinergics and/or amantadine, while 13 patients who had never taken L-Dopa were treated only with anticholinergics and/or amantadine, or were without any medication. Piribedil (in the retard form) was administered orally at a gradually increasing dose up to 200 mg daily, while previous antiparkinsonian medication remained unchanged. Twenty-five patients showed statistically significant improvement. Among the cardinal symptoms of parkinsonism, tremor responded the best. Depression also appeared to respond favorably. Our results indicate that piribedil may be a useful adjuvant in the treatment of PD.

Aged↗
PubMed1987

Regional spinal cord blood flow measurements (r.S.C.B.F.) in spinal cord acute compression caused by an epidural balloon.

Our study was carried out in 34 rabbits which were divided into three groups (A, B, C). In group A (10 animals), a mid-laminectomy of the first lumbar (L1) vertebra was performed and the circulation in the exposed spinal cord segment was examined using both procedures, the videomicroscopy as well as the r.S.C.B.F. measurement (by intraarterial-5th radicular injection of 2.5 mic133 Xe). In group B (10 rabbits) after the performance of L1 vertebra mid-laminectomy, a teflon catheter was introduced through T11-T12 (thoracic) intervertebral foramina and 0.5 ml of metrizamide sodium was injected through the balloon producing, thus, a 36 +/- 1% stenosis in the diameter of the corresponding spinal canal level. Using the procedures described above as well as light microscopy it was shown that, during the period of the 4 hours the experiment lasted, the circulatory disturbances of spinal cord were still reversible. On the contrary, in group C (14 rabbits) where 0.8 ml of metriz amide sodium was injected through the balloon catheter producing, thus, a 52 +/- 1% stenosis in the corresponding spinal canal level, the spinal cord disturbances proved irreversible after the 4-hour period of the experiment's duration.

Acute Disease↗
PubMed1987

Improvement of cerebral circulation by extracorporal collateral between the femoral and the external carotid artery in experimentally induced ischaemia.

The purpose of this study was to examine the effect of extracorporal collateral circulation (ECCC) between the femoral and the external artery (ECA) on the cerebral circulation, in experimentally induced ischaemia, in rabbits. The animals were divided in four groups. Seven animals (Group A) were used to determine the injection pressure (150-160 mmHg) at the ECA, necessary to achieve collateral circulation between ECA and internal carotid artery (ICA), after occlusion of ICA. Group B (8 rabbits) was the control group for establishing cerebral ischaemia (CI) by a) ligating the common carotid artery bilaterally, b) coagulating the right vertebral artery and c) exsanguinating the animal (removing 28-30 ml of blood). The induced ischaemia was studied by BP and PCO2 monitoring, CBF measurement, videomicroscopy of surface cerebral vessels, and finally macroscopic and microscopic examination of brain sections. In group C (8 animals)-moderate degree of CI-brain circulation improved in all animals after the application of the ECCC, installed at 135 min after the onset of CI. In 10 animals (group D) with severe and prolonged (225 min) CI, ECCC enhanced the brain circulation in eight animals to a variable degree.

Animals↗
PubMed1987

The pharmacological effects of buflomedil in patients with multi-cerebral infarcts dementia: an open, preliminary assessment.

The influence of buflomedil on brain circulation was investigated in an open, preliminary trial in 12 patients with dementia caused by multi-cerebral infarcts. Patients were given 150 mg buflomedil 3-times daily for a period of 6 months. Assessments carried out before treatment included regional cerebral blood flow measurements, using a 133Xenon technique, as well as psychometric tests (Weschler and Benton), psychiatric and neurological evaluations, and routine clinical and laboratory (blood and urine) examinations. The tests and investigations were repeated on Days 90 and 180 of treatment. The results showed that mean regional cerebral blood flow increased by 15% to 22% and 16% to 24% in the right and left hemispheres, respectively, by the end of the trial, and marked improvements were noted in psychiatric symptoms and scores in the psychometric tests. A controlled, double-blind study is being planned to validate these preliminary findings.

Aged↗
PubMed1986

Sleep deprivation as a method of EEG activation. Observation on the incidence of positive responses.

Sleep deprivation is known to be one of the principal mechanisms to activate epileptogenic activity in the EEG recording and indeed it is one of the most common activation techniques in EEG practice. It is generally recognized that about one third of patients with seizures presenting a normal or borderline normal routine EEG may be expected to exhibit an abnormal paroxysmal recording after sleep deprivation. In the present study it was estimated that activation, by sleep deprivation, of a normal EEG into a record with abnormal paroxysmal activity, may be expected to be even higher with selection of patient population. The incidence of such activation was found to be 23% among patients presenting a history of attacks with variable clinical paroxysmal manifestations with or without impairment of consciousness, but in whom the overall picture could not be judged typically epileptic upon historical grounds alone. However, the incidence of activation was found to increase up to 57% among patients with attacks judged by history to be typical as to their epileptic nature. This higher incidence of activation appears to parallel the higher incidence of underlying abnormality as revealed by CAT scanning.

Diagnosis, Differential↗
PubMed1985

A contribution to the pathogenesis of respiratory disturbances associated with subarachnoid haemorrhage; an experimental approach using an animal model.

The present experimental work focuses on the mechanisms involved in respiratory distress observed in the course of subarachnoid haemorrhage. For this purpose, respiratory disturbances were induced in rabbits by injecting fresh autologous blood into the subarachnoid space. For six hours after this artificially induced SAH, blood PO2 and PCO2 as well as expiratory air CO2 were regularly determined, while during the same period cerebral blood flow and cerebrospinal fluid pressure measurements were recorded. The results of this study suggest that pressure effects acting the brain structures that support respiration are principally involved in the pathogenesis of respiratory disturbances following SAH. A decrease in CBF and hypoxia with hypercapnia play a contributing secondary role adding to a vicious cycle phenomenon.

Animals↗
PubMed1985

Flunarizine in the prevention of classical migraine: a placebo-controlled evaluation.

Pharmacological data and early clinical experience have suggested that the calcium entry blocker flunarizine may be a valuable asset in the prophylaxis of migraine. This was supported by a study in twenty patients with classical migraine who were, after a drug-free running-in phase, orally treated with either placebo or flunarizine (10 mg at night) for three to four months. Flunarizine significantly reduced the frequency, duration and severity of the migraine attacks. A corrected migraine index, based on these three variables, was reduced by 82% in the drug group but increased by 66% in the control patients. Only one patient did not clearly benefit from flunarizine, and the response in another illustrated that flunarizine has to be given for at least four months before its efficacy can be judged in some cases. No side effects occurred.

Adult↗
PubMed1983

A new model of subarachnoid hemorrhage in experimental animals with the purpose to examine cerebral vasospasm.

Using 20 rabbits, we tried to establish a new model of experimental subarachnoid hemorrhage (SAH) for examining both acute and chronic cerebral vasospasm. A cranial opening was drilled, and a puncture made on the posterior branch of the middle cerebral artery. A second puncture was made in the superior sagittal sinus for additional withdrawal of subarachnoid blood. The bleeding thus induced resulted in arterial spasm which was studied by using serial electrocorticograms, cerebral blood flow measurement with 133Xe, and videomicroscopy of the small pial vessels at various intervals. After death of the animals, the brains were observed to identify the extention of the bleeding. It was indeed obvious that large amounts of subarachnoid blood clots had accumulated. This investigation showed that the rabbit can be used as a new experimental model of SAH. With a two-puncture method, it is possible to simulate the clinical phenomenon of a ruptured aneurysm, that seems to produce acute and chronic cerebral vasospasm. For the latter, the accumulation of blood clots in the basal surfaces plays an important role. The three methods of observation, videomicroscopy, cerebral blood flow measurements, and electrocorticography appeared to provide useful information in the study of biphasic vasospasm in the rabbit.

Animals↗
PubMed1981

Side effects in preventive maintenance therapy with neuroleptics with special emphasis on tardive dyskinesia.

Neuroleptics induce hypersensitivity reactions, and toxic, systemic and extrapyramidal manifestations. The latter mainly include acute dystonic reactions, other early dyskinesias, akathisia, parkinsonism and TD. These drugs have been implicated for DA antagonism exerted by an adenylate cyclase inhibition. Prolonged blockade of DA receptors is considered as the motivation for a counterbalancing mechanism inducing the DA supersensitivity from which TD results. Recent reports suggest cholinergic and GABA ergic insufficiency as secondary participants. The increasing frequency of TD calls for prevention by modifying treatment practices and searching for effective measures to combat the symptoms.

Antipsychotic Agents↗
PubMed1981

The need for continuous use of antiparkinsonian medication with chronic schizophrenic patients receiving long-term neuroleptic therapy.

In this double-blind six-week study, 98 chronic schizophrenic patients receiving long-term neuroleptic treatment and trihexyphenidyl were switched to either placebo or study trihexyphenidyl. Fifty-one (68%) of the 75 patients given placebo versus 1 of the 23 patients who continued on active trihexyphenidyl developed severe worsening of extrapyramidal signs, necessitating early termination from the study. Twenty-one (28%) of the placebo patients versus 2 (8.7%) of the trihexyphenidyl patients developed less severe worsening. Furthermore, 50 (66.6%) of the placebo patients but only 2 (8.7%) of the trihexyphenidyl patients had psychotic or other severe physical symptoms related to withdrawal of prestudy antiparkinsonian medication. The authors conclude that these data support the need for continuous use of antiparkinsonian medication in the long-term neuroleptic therapy of chronic schizophrenic patients.

Adult↗