Biomedical subjects

G Vallar

Publications and source records attributed to G Vallar.

At least 55 records · Page 3Linked to original sources

PubMed1993

Hemianopia, hemianaesthesia, and hemiplegia after right and left hemisphere damage. A hemispheric difference.

The incidence of somatosensory, visual half-field and motor deficits contralateral to a hemispheric lesion in a continuous series of 154 left brain damaged and 144 right brain damaged stroke patients were investigated. These contralateral disorders were more frequent after lesions of the right hemisphere. This difference cannot be attributed to a bias in patients' selection. It is suggested that left spatial neglect is the factor underlying this hemispheric difference.

Aged↗

PubMed1993

Increased serum IgA levels in subjects with previous myocardial infarction or other major ischemic events.

To ascertain whether the increase in serum IgA, which has been found to be associated with the presence of severe atherosclerotic disease, precedes or follows the occurrence of major ischemic events (MIE), we studied the serum levels of IgA as well as IgG and IgM in 145 subjects with acute or previous ischemic events and 34 controls. The subjects with previous myocardial infarction had higher IgA levels with respect to the controls, the patients with angina pectoris and those with acute myocardial infarction, while no significant differences concerning IgG and IgM were found. In the subjects with previous extracoronary events, immunoglobulin levels tended to be even higher. Overall, 30% of the subjects with previous MIE and only 3% of the controls had IgA levels over 4.5 g/l (p = 0.0018). This study indicates that total serum IgA is a marker of previous major ischemic events (protracted immune response to denatured proteins?), rather than a factor predisposing to atherosclerosis development.

Aged↗

PubMed1992

Auditory and visual verbal short-term memory in aphasia.

Phonological short-term memory was investigated in 24 aphasic left brain-damaged patients and in 12 matched controls. Aphasic patients have a reduced auditory and visual immediate memory span and show the standard detrimental effect of phonological similarity on immediate retention only when the stimuli are auditorily presented, while in the control group the effect is present with both auditory and visual input. Most patients have phonological processing deficits, but two patients have an impaired immediate verbal memory in the absence of analysis disorders. These results, in line with most individual case studies of patients with selective deficits of verbal short-term memory, are interpreted with reference to a model distinguishing a phonological short-term store component of memory, to which auditory input has direct and automatic access, and a rehearsal component, that, after phonological recoding, conveys visually presented stimuli to the phonological store. This latter system, that appears to become fully operational later in development, is less resistive to brain damage.

Adult↗

PubMed1992

Metabolic impairment in human amnesia: a PET study of memory networks.

Human amnesia is a clinical syndrome exhibiting the failure to recall past events and to learn new information. Its "pure" form, characterized by a selective impairment of long-term memory without any disorder of general intelligence or other cognitive functions, has been associated with lesions localized within Papez's circuit and some connected areas. Thus, amnesia could be due to a functional disconnection between components of this or other neural structures involved in long-term learning and retention. To test this hypothesis, we measured regional cerebral metabolism with 2-[18F]fluoro-2-deoxy-D-glucose ([18F]FDG) and positron emission tomography (PET) in 11 patients with "pure" amnesia. A significant bilateral reduction in metabolism in a number of interconnected cerebral regions (hippocampal formation, thalamus, cingulate gyrus, and frontal basal cortex) was found in the amnesic patients in comparison with normal controls. The metabolic impairment did not correspond to alterations in structural anatomy as assessed by magnetic resonance imaging (MRI). These results are the first in vivo evidence for the role of a functional network as a basis of human memory.

Adult↗

PubMed1992

Oxiracetam in dementia: a double-blind, placebo-controlled study.

A multicentre, double-blind, between-patient study was carried out to evaluate the efficacy and tolerability of oxiracetam (800 mg tablet), in comparison with placebo, each given twice daily for 12 weeks to patients suffering from primary degenerative, multi-infarct or mixed dementia. Efficacy was assessed by a neuropsychological battery (simple reaction time, controlled associations, short story, Raven's Progressive Matrices, token test, digit span, word list learning), administered at the beginning and at the end of the study, and by a quality of life scale, administered at entry and after 6 and 12 weeks treatment. Sixty-five patients (28 men, 37 women, mean age 71 yrs) were enrolled; 58 completed the study: 2 on oxiracetam were withdrawn because of poor tolerability, 2 (one in each group) were withdrawn for poor compliance, one (on oxiracetam) for the occurrence of a transient ischaemic attack (defined as not related to the treatment) and 2 for administrative reasons. A significantly (p < 0.01) different effect in favour of oxiracetam was observed on the quality of life scale, and confirmed by significant (defined according to the Bonferroni technique) differences in some neuropsychological tests (e.g. controlled associations, short story). Four patients in the oxiracetam group complained of a total of 5 unwanted effects, and 1 on placebo complained of 3 unwanted effects, but none of them was withdrawn from the study.

Aged↗

PubMed1992

Directional hypokinesia in spatial hemineglect: a case study.

A patient with an ischaemic lesion involving the right frontal lobe and basal ganglia showed left spatial hemineglect in visuomotor exploratory tasks, requiring the use of the right unaffected hand. Her performance was, however, entirely preserved, with no evidence of neglect, when she was required to identify targets among distractors in both the left and right halves of space, and in the Wundt-Jastrow illusion test. The latter tasks do not require any arm movement in extrapersonal space. In this patient spatial hemineglect may be explained in terms of defective organisation of movements towards the left half-space (directional hypokinesia). The frontal lesion of the patient may be the neural correlate of this selective disorder. This pattern of impairment may be contrasted with the typical deficit found in patients with right brain damage with perceptual neglect. One case had a defective performance both in visuomotor and in purely perceptual tasks.

Aged↗

PubMed1992

[Association of serum C3 and essential hypertension].

This study was performed to assess the possible involvement of humoral immunity in essential hypertension, independently of the presence of atherosclerotic disease, which in turn may be associated with immunologic changes. Sixty-five patients without demonstrated atherosclerotic disease were selected according to clinical and arteriographic criteria, including 23 hypertensive subjects (all pharmacologically treated) and 42 controls. Mean ages (58.7 +/- 8.3(1 S.D.) years in the controls and 57.7 +/- 7.9 years in the hypertensive subjects) and sex distribution were similar in the 2 groups. Of the main risk factors, atherosclerosis, smoking, diabetes, total cholesterol and HDL-cholesterol were equivalent, while triglycerides were higher in the hypertensive subjects than in the controls (142.6 +/- 52.7 vs. 112.6 +/- 67.7 mg/dl; p = 0.0065). In these subjects' sera the immunoglobulins IgG, IgA and IgM, and the third and fourth complement components (C3 and C4) were measured. Of these variables, only C3 was higher in the hypertensive subjects than in the controls (124.3 +/- 29.3 vs. 107.8 +/- 18.4 mg/dl; p = 0.0183). Furthermore, C3 was significantly correlated with triglycerides (tau = 0.3613; p < 0.0001), but the association with hypertension was confirmed only for C3, and not for triglycerides, by multiple logistic regression (p = 0.0142). The increase in serum C3 suggests the possible implication of humoral immunity in the pathogenesis or progression of essential hypertension.

Blood Pressure↗

PubMed1992

[Variations in neuropeptide Y plasma levels in acute myocardial infarction].

The aim of the study was to measure plasma neuropeptide Y (NPY) in patients with acute myocardial infarction (AMI). Eighteen patients (13 females and 5 males; range 55 to 75 years) admitted both early (n 12; mean preadmission time 3 +/- 2 hours) and late (n 6; mean preadmission time 25 +/- 16 hours) to Coronary Care Unit were studied. Plasma NPY values significantly above normal range (15-25 pg/ml) and early admitted patients (26 +/- 10 pg/ml) have been found in late admitted patients (72 +/- 28 pg/ml; p < 0.05) both on the admission and during the stay in the Coronary Care Unit (96 hours). In early admitted patients no significant correlation was found between both AMI localization and the thrombolytic treatment. A significant increase in plasma NPY levels has been observed in all patients with complicated myocardial infarction (both in subclinic and clinic heart failure or extension of infarct size). According with the literature data our results have shown a significant correlation between increase of plasma NPY levels and failure of myocardial pump. Moreover, the plasma NPY increase which has been observed in preclinic heart failure when plasma catecholamine levels is usually not significantly different from normal values, may be a useful and reliable prognostic marker.

Aged↗

PubMed1992

[Neuropeptide Y and heart failure].

A time course (48 hours) of plasma neuropeptide Y (NPY) levels has been carried out in a male, 66 years old, admitted to Coronary Care Unit with inferior acute myocardial infarction within 1 hour from the onset of chest pain. On admission an increase of plasma NPY levels (38 pg/ml) has been observed. The plasma NPY value decreased to normal range (15-25 pg/ml) within 12 hours and increased again (53 pg/ml) within 12 and 24 hours. A decrease in plasma NPY values to normal range has been observed within the second day in the Coronary Care Unit. A clearcut diuresis decrease, without pulmonary signs of heart failure, was present from 12 to 24 hours followed by marked polyuria within the second day. These data point out a relative importance of NPY in the diuresis adjustments. Thus, plasma NPY measurement might be a more reliable prognostic indicator of heart failure than plasma catecholamine levels. However, further investigations have to be performed.

Aged↗

PubMed1992

[Increased serum levels of IgA and C4 in atherosclerosis: the absence of a correlation with the arteriographic picture].

We have previously shown that an increase in serum IgA and C4 is often detectable in presence of diffuse atherosclerotic disease. The present study was performed to verify such results in a different and larger sample of subjects, and to ascertain whether the above immunologic variables are correlated with the severity of atherosclerotic disease. Seventy-three atherosclerotic subjects with at least 1 significant (> 75%) stenosis in a major arterial branch were selected according to the reports of arterial panangiographies performed previously. Among them, 36 subjects (24 men and 12 women, mean age 63 +/- 7 years) were singled out, who matched by age and sex 36 control subjects (mean age 63 +/- 7 years). In all of these subjects the following serum immunologic and lipid variables were measured: IgG, IgA, IgM, IgE, C3, C4, total cholesterol, HDL-cholesterol and triglycerides. With respect to the controls, the 36 matched atherosclerotic subjects had higher levels of IgA (263.0 +/- 119.8 vs 334.3 +/- 130.5 mg/dl; p = 0.0126), C4 (25.7 +/- 5.8 vs 30.4 +/- 9.1 mg/dl; p = 0.0297) and triglycerides (153.1 +/- 77.3 vs 209.7 +/- 141.3; p = 0.0500). No correlation was found between the number of arterial stenoses (range 1-8, mean 2.9 +/- 1.5) and any of the immunologic or lipid parameters in all the 73 atherosclerotic subjects. Only the daily cigarette consumption was correlated with the disease extension (tau = 0.1984; p = 0.0392).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1991

Remission of somatoparaphrenic delusion through vestibular stimulation.

The effects of vestibular stimulation on somatoparaphrenic delusion were investigated in a patient suffering from a fronto-temporo-parietal infarction located in the right hemisphere. Transitory remission of the patient's delusional belief was consistently observed during unilateral vestibular activation obtained by means of cold-water irrigation of the left (contralesional) ear.

Aged↗

PubMed1991

Long-term recency effects and phonological short-term memory. A neuropsychological case study.

Long-term recency effects were investigated in a left brain-damaged patient, PV, who had a pathologically low auditory-verbal span and a lack of the normal recency effects in immediate free recall of auditorily presented lists of words, attributed to the abnormally reduced capacity of the phonological short-term store component of memory (Vallar and Papagno, 1986). In a task requiring the delayed free recall of a list of anagram solutions the patient showed both a recall performance level and a long-term recency effect comparable to the control group. These findings dissociate long and short-term recency phenomena, which would reflect the operation of different memory components. A collateral finding was PV's difficulty in anagram solving, which may be traced back to the defective function of her phonological short-term store.

Adult↗

PubMed1991

Hemianopia, hemianesthesia, and spatial neglect: a study with evoked potentials.

We recorded somatosensory or visual evoked potentials (SEPs, VEPs) to stimuli contralateral and ipsilateral to the lesion in three right-brain-damaged patients with left spatial hemineglect and in three left-brain-damaged patients without evidence of neglect, as assessed by visual exploratory tasks. All patients had contralateral homonymous hemianopia or hemianesthesia. The three neglect patients showed normal SEPs or VEPs to stimuli delivered to the left half-field or to the left hand, without conscious perception and verbal report of the stimulation. By contrast, the three left-brain-damaged patients without neglect showed no recognizable cortical evoked response to contralateral visual or somatosensory stimuli. In all patients, the cortical evoked responses to ipsilateral stimulation were normal. In patients with spatial hemineglect, hemianopia and hemianesthesia may be manifestations of the neglect syndrome (visual and somatosensory hemi-inattention), rather than representing primary sensory deficit. Visual and somatosensory hemi-inattention may be due to defective access to the neural processes subserving conscious perception by information that has undergone early sensory processing.

Aged↗

PubMed1991

Hemianesthesia, sensory neglect, and defective access to conscious experience.

We report a patient with an ischemic stroke in the vascular territory of the right middle cerebral artery who had left spatial neglect and left hemianesthesia. The patient showed a dissociation between defective verbal reporting of somatosensory stimuli delivered to the left hand and physiologic evidence from an autonomic index. This indicates that there was processing of undetected stimuli without the patient's awareness, and suggests that the hemianesthesia was due, at least in part, to somesthetic hemi-inattention.

Cerebral Angiography↗

PubMed1991

Visual and nonvisual neglect after unilateral brain lesions: modulation by visual input.

A spatial exploratory task was given to 110 patients with unilateral brain lesions [66 right brain-damaged (RBD) patients and 44 left brain-damaged (LBD) patients] in two conditions, with and without the aid of vision. Exploratory deficits mainly involved the contralesional half-space and were most frequently associated with right brain damage. A double dissociation was found between the visual and the nonvisual conditions of the task; selective impairments in the visual and in the nonvisual condition were associated with the presence and the absence of visual field deficits, respectively. The suggestion is made that discrete "visual" and "tactile-kinesthetic" spatial representational systems are involved in exploration of extrapersonal space. A further distinction is made between input and output spatial system. The association between visual field deficits and visual neglect is explained in terms of the impairment of an input visuospatial component, which feeds an output component involved in spatial exploration. Finally, the ambiguous nature of the visual field deficits in neglect patients is discussed and the suggestion is made that an attentional modality-specific nonsensory component may be present.

Brain Damage, Chronic↗

PubMed1990

Language and verbal memory after right hemispheric stroke: a clinical-CT scan study.

The performances on language and verbal memory tests of 26 right-hemisphere damaged subjects (RHD) have been compared with normal controls and 11 non-aphasic left-hemisphere damaged subjects. While phonological and syntactic performance was unimpaired, a small subgroup of RHD patients, with CT scan evidence of subcortical lesion, was mildly impaired in naming tasks. The performance of RHD patients on free recall was characterized by a reduced recency effect. The implications of these findings for theories about the participation of the right hemisphere in linguistic functions are discussed.

Adult↗

PubMed1990

Temporary remission of left hemianesthesia after vestibular stimulation. A sensory neglect phenomenon.

In three right-brain damaged patients with contralesional neglect vestibular stimulation induced a temporary remission of left hemianesthesia, in addition to the well-known transient recovery of extrapersonal and personal neglect. These findings indicate that in neglect patients attentional factors may play an important role in producing apparently "primary" sensory deficits, which may be interpreted in terms of defective access to conscious processing.

Aged↗

PubMed1989

Visual neglect for far and near extra-personal space in humans.

The possible dissociation of unilateral neglect in far and near extra-personal space was systematically investigated using a modified version of the Wundt-Jastrow area illusion test. This task, which requires no motor response, has been shown to be sensitive to unilateral neglect. Stimuli were presented at two different distances (near and far) to a group of 70 patients with right hemispheric lesion (18 in acute and 52 in chronic stage). Twenty-eight patients evidenced unilateral neglect; that is, they displayed unexpected (i.e., contrary to the known illusory effect) responses when the stimuli were perceived as oriented toward the left side. However, performances in the two conditions were highly correlated and there were no individual instances of dissociation. These results suggest that the presence of a motor response may be necessary to show behavioral dissociations between different parts of extra-personal space.

Adult↗