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Biomedical subjects

M LeMay

Publications and source records attributed to M LeMay.

At least 19 recordsLinked to original sources
PubMed2002

Visual deficits in a patient with 'kaleidoscopic disintegration of the visual world'.

We describe psychophysical, neuropsychological and neuro-ophthalmological studies of visual abilities in a patient who, following a right hemisphere stroke, had difficulty in combining parts of objects into a whole and in reading. Strikingly, her perceptual problems were accentuated when the objects moved or when she moved. Formal testing showed that her main deficits were in depth perception, various tasks of motion and object recognition of degraded stimuli. But low-level detection and discrimination of form and color were normal. Despite her deficits in visual motion and degraded static-object recognition, her visual recognition of 'biological motion' stimuli was normal. Structural magnetic resonance imaging revealed an infarct in the ventro-medial occipito-temporal region, extending ventro-laterally and leading to a 'kaleidoscopic disintegration of visible objects'.

Adrenalectomy↗
PubMed2001

Regional cerebral correlates of global motion perception: evidence from unilateral cerebral brain damage.

We used a psychophysical task to measure sensitivity to motion direction in 50 stroke patients with unilateral brain lesions and 85 control subjects. Subjects were asked to discriminate the overall direction of motion in dynamic stochastic random dot displays in which only a variable proportion of the spots moved in a single direction while the remainder moved randomly. Behavioural and neurophysiological evidence shows that the middle temporal (MT/V5) and middle superior temporal (MST) areas in the macaque monkey are indispensably involved in the perception of this type of motion. In human subjects too, lesions in the same region disrupt performance on this task. Here we assessed more extensively the correlation between direction sensitivity for global motion and the anatomical locus of the lesion. Thresholds for perceiving the direction of global motion were impaired in the visual field contralateral to the lesion in patients with lesions in the occipitoparietal and parietotemporal areas involving the human analogue of areas MT/V5 and MST, but not by lesions in the occipito-temporal or anterior frontal areas. Patients with lesions involving the anterior temporal or parietal lobes displayed poor performance for stimuli presented in either visual field, which is consistent with the large and bilateral receptive fields in these areas in monkeys. The perception of global motion was also more impaired in the centripetal than the centrifugal direction in the hemifield contralateral to the MT/V5 lesion. Surprisingly, thresholds were normal in all patients when the displays contained static but not dynamic visual noise, suggesting that their deficit reflects an inability to filter out dynamic noise. Although frequent repeated testing of some patients whose lesion involved the human homologue of MT was accompanied by an improvement in performance, this was no greater than in other patients who received training on different motion tasks.

Adult↗
PubMed1993

Design features of a controlled clinical trial to assess the effect of an HMG CoA reductase inhibitor on the progression of coronary artery disease. Canadian Coronary Atherosclerosis Intervention Trial Investigators Montreal, Ottawa, and Toronto, Canada.

This report describes the design and methodological features of a double-masked, randomized, placebo-controlled trial to determine whether administration of the HMG CoA reductase inhibitor lovastatin retards the progression or facilitates the regression of coronary atherosclerosis. The study population consists of coronary patients with a recent arteriogram that characterizes them as being at high risk for coronary progression and a baseline fasting total serum cholesterol > or = 5.7 mmol/L and < or = 7.8 mmol/L. Lovastatin, or matching placebo, are up-titrated from 20 mg to 40 mg to 80 mg/day during the first 16 weeks of the study in an attempt to attain a fasting serum LDL cholesterol level of 3.4 mmol/L; patients and study personnel remain masked as to cholesterol levels throughout the trial. Coronary arteriography is repeated at 2 years, or earlier if necessitated by worsening symptoms, and all segments are measured quantitatively using a computer-based system. The primary outcome of the trial is a comparison between the lovastatin and placebo groups for coronary change score, defined as the mean of the minimum lumen diameter changes for all lesions (follow-up minus baseline arteriogram) per patient. The advantages and limitations of coronary arteriographic trials and some of the issues related to outcome measurements are discussed. The question posed by this study is of clinical relevance because the consequences of progression of coronary disease, angina, myocardial infarction, and sudden cardiac death are leading causes of morbidity and mortality.

Adult↗
PubMed1993

The value of the chest X-ray in making the diagnosis of bronchial asthma.

Although bronchial asthma is one of the most common chronic illnesses of children and young adults, it remains underdiagnosed. To assess the value of the chest X-ray in helping to make the diagnosis of asthma at the primary care level, we studied the medical records of 58 patients aged 18-40 with the diagnosis of mild to moderate asthma and for whom both simple spirometry-forced one-second expiratory volume (FEV1) and/or peak expiratory flow rate (PEFR)--and a chest X-ray had been performed. Only 21 of 58 (36%) had spirometry indicative of asthma (SPI+) while 34 of 58 (59%) had abnormal chest X-rays (CXR+)--"increased markings" and/or "low diaphragm." Although CXR+ discriminated between asthmatic patients and a normal control group, no difference was found between asthmatic patients and a group of patients with acute bronchitis. Nonetheless, the number of asthmatic patients with CXR+ and SPI - (n = 23) was significantly larger than the number with CXR- and SPI+ (n = 10), which indicates that for mild asthma the chest X-ray may be more sensitive than spirometry even though not as specific. These results were surprising at the time of the investigation. Subsequently, however, the importance of the inflammatory response in asthma came to light, which rendered the results more interesting than surprising. We conclude that the chest X-ray has value in making the diagnosis of mild bronchial asthma.

Acute Disease↗
PubMed1992

Abnormalities of the left temporal lobe and thought disorder in schizophrenia. A quantitative magnetic resonance imaging study.

BACKGROUND: Data from postmortem, CT, and magnetic resonance imaging (MRI) studies indicate that patients with schizophrenia may have anatomical abnormalities of the left temporal lobe, but it is unclear whether these abnormalities are related to the thought disorder characteristic of schizophrenia. METHODS: We used new MRI neuroimaging techniques to derive (without knowledge of the diagnosis) volume measurements and three-dimensional reconstructions of temporal-lobe structures in vivo in 15 right-handed men with chronic schizophrenia and 15 matched controls. RESULTS: As compared with the controls, the patients had significant reductions in the volume of gray matter in the left anterior hippocampus-amygdala (by 19 percent [95 percent confidence interval, 3 to 36 percent]), the left parahippocampal gyrus (by 13 percent [95 percent confidence interval, 3 to 23 percent], vs. 8 percent on the right), and the left superior temporal gyrus (by 15 percent [95 percent confidence interval, 5 to 25 percent]). The volume of the left posterior superior temporal gyrus correlated with the score on the thought-disorder index in the 13 patients evaluated (r = -0.81, P = 0.001). None of these regional volume decreases was accompanied by a decrease in the volume of the overall brain or temporal lobe. The volume of gray matter in a control region (the superior frontal gyrus) was essentially the same in the patients and controls. CONCLUSIONS: Schizophrenia involves localized reductions in the gray matter of the left temporal lobe. The degree of thought disorder is related to the size of the reduction in volume of the left posterior superior temporal gyrus.

Adult↗
PubMed1992

Reversed cerebral asymmetry in women with breast cancer.

Altered intrauterine hormonal environment might predispose to both atypical cerebral asymmetry and breast cancer. We therefore investigated computed tomographic scans of 79 right-handed, white patients with breast cancer and 97 controls to assess the pattern of cerebral asymmetry. Women with breast cancer had a reversed pattern of cerebral asymmetry significantly more often than did controls (p less than 0.0001 for both frontal and occipital width. Our findings suggest that an intrauterine or early life factor, probably hormonal, could predispose to breast cancer in adulthood.

Brain↗
PubMed1992

Empirically derived personality subtypes of public psychiatric patients: effect on self-reported symptoms, coping inclinations, and evaluation of expressed emotion in caregivers.

Personality scales on the Millon Clinical Multiaxial Inventory-II (MCMI-II) for 195 psychiatric inpatients (93 men and 102 women) in a public facility were cluster analyzed to develop an empirical subtyping according to personality traits. Subjects also completed the Brief Symptom Inventory (BSI), Methods of Coping Scale (MOC), and the Level of Expressed Emotion Scale (LEE). The five personality subtypes that emerged were consistent across two clustering methods (K-means and complete linkage). Subtypes members differed on subscales of the BSI, MOC, and LEE. Results support the relevance of personality traits and disorders in assessing psychopathology in psychiatric patients. Results also support the relevance of subtyping these patients according to MCMI-II results.

Adaptation, Psychological↗
PubMed1990

The relationship between enlargement of the temporal horns of the lateral ventricles and dementia in aging patients with Down syndrome.

Head CT studies of patients with Alzheimer's disease (AD) show global atrophic changes. Tissue loss is especially prominent in the temporal lobes, with widening of the temporal horns of the lateral ventricles and, usually, widening of the temporal sulci. Some recent studies have found a familial form of AD to be mapped to chromosome 21. Down syndrome (DS) results from the inheritance of three chromosomes 21, and it has been shown that after the age of 35 the brains of patients with DS commonly show neuropathological changes similar to those in patients with AD. CT studies of 25 patients with DS (ages 29-64 years) were examined for tissue loss in the temporal regions, and this was compared to the findings commonly seen in patients with AD. The widths of CSF spaces varied considerably in patients with DS, but after the age of 50 most of them showed significant widening of the temporal horns. In some patients the horns were large enough to suggest obstructive hydrocephalus. Because of a new trend toward deinstitutionalization of patients with DS, radiologists will be seeing more studies on these patients and should familiarize themselves with the unique ways in which they manifest the aging process.

Activities of Daily Living↗
PubMed1989

CT abnormalities in schizophrenia. A preliminary study of their correlations with P300/P200 electrophysiological features and positive/negative symptoms.

Computed tomographic scans were scored blindly for the size of cerebrospinal fluid spaces in a group of nine medicated schizophrenics and a group of nine age-matched normal volunteers without psychiatric or medical problems. Overall, ten of the 18 computed tomography (CT) features measured were significantly enlarged in the schizophrenic group. These abnormal CT features were then correlated with electrophysiological and clinical measurements performed on the schizophrenic patients. Left sylvian fissure enlargement, thought to reflect temporal lobe tissue loss, was highly correlated with a left temporal scalp region feature of the auditory P300 measure (T3 electrode) that differentiated schizophrenics and normals, and both the left sylvian fissure enlargement and the P300 measure were highly correlated with positive symptoms (total score on the Scale for the Assessment of Positive Symptoms). Frontal superficial (cortical) sulcal enlargement was prominent in the schizophrenic group and was highly correlated with another electrophysiological measure, auditory P200, at left central scalp locations. There was no significant correlation between left sylvian fissure and frontal sulcal enlargement within the schizophrenic group, and intercorrelations between CT variables in the schizophrenic group were, in general, less significant than in the control group. Although we should be cautious about generalizability because of the small number of patients, these data are compatible with the hypothesis that different subgroups of schizophrenic pathological features are characterized by different CT, electrophysiological, and clinical presentations.

Adult↗
PubMed1988

Comparison of ioxaglate with diatrizoate in angiography of the internal mammary artery.

To compare ioxaglate with the traditional agent diatrizoate, 44 patients scheduled to undergo coronary angiography that included internal mammary artery (IMA) visualization were entered into a randomized double blind-parallel design protocol. Complete data were collected on 32 out of 44. Four patients were withdrawn because of angiographically normal coronary arteries; seven, because of unsuccessful IMA cannulation; and one, because of an anaphylaxis-like reaction to ioxaglate. No other serious adverse effects were seen with either agent. The major endpoints were patient and physician assessments of discomfort, rated independently on a 4-point scale. Ioxaglate caused significantly less discomfort (n = 17, median rating of "mild discomfort") than did diatrizoate (n = 15, median rating of "severe discomfort"; P less than 0.01); this effect was independent of patient sex, the number of injections, and the volume of dye injected. Radiographic quality was good with both agents. We conclude that ioxaglate is much better tolerated than diatrizoate during angiography of the IMA.

Diatrizoate↗
PubMed1988

Acquired immunodeficiency syndrome: a new population of children at risk.

Cases of AIDS in children have been described since 1982. Diagnosis is more complex in children than in adults owing to the more varied clinical presentations and the difficulty in interpretation of laboratory tests. Our current understanding of HIV infection in children is reviewed, as well as the controversies regarding medical, psychosocial, and public health issues.

Acquired Immunodeficiency Syndrome↗
PubMed1986

CT changes in dementing diseases: a review.

The present review describes the primary CT features of a variety of dementing disorders. An understanding of the differential neuropathologic and CT changes occurring in dementing illnesses can greatly increase the diagnostic utility of CT. CT is valuable not only in diagnosing space-occupying lesions but also in recognizing numerous degenerative brain diseases.

Brain Diseases↗
PubMed1984

Radiologic changes of the aging brain and skull.

Computed tomographic (CT) studies during life reveal the involutionary changes in the brain found in postmortem studies. Beginning about the fourth decade, gradual widening of the third ventricle, sylvian and interhemispheric fissures, superficial sulci, and basal cisterns occurs. Enlargement of the lateral ventricles is most striking after the sixth decade of life. Regression of the brain with aging is a normal process. There is marked individual variation in the degree of involutional changes; not all lives are identical, and the longer the life span the less predictable one would expect the involutionary changes to be.

Adolescent↗
PubMed1982

Normal ventricles in young schizophrenics.

The CT scans of 11 schizophrenics and 26 controls were evaluated for both linear (Evan's and cella media ratios) and volume (planimetry and grid ratios) measurements of ventricular size. There were no differences between the two groups on any of the measures obtained. These results are discussed in relation to previous reports showing ventricular enlargement in schizophrenics. The relatively younger age and briefer period of hospitalization in this present sample are suggested as variables possibly associated with these findings.

Adult↗