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G Rodriguez

Publications and source records attributed to G Rodriguez.

At least 19 recordsLinked to original sources
PubMed2007

99mTc-HMPAO and 99mTc-ECD brain uptake correlates of verbal memory in Alzheimer's disease.

AIM: Technetium-99m hexamethylpropylene amine oxime ((99m)Tc-HMPAO) and technetium-99m N,N-1,2-ethylene diylbis-Lcysteine diethyl ester dihydrochloride ((99m)Tc-ECD) SPECT are widely used in Dementia Clinics for early and differential diagnosis. They have been shown to perform differently in Alzheimer's disease (AD), but the impact of such differences on both research and clinical work is unknown. We investigated the differences between the 2 compounds in research work by assessing correlation between performance on a verbal memory task and cerebral perfusion in 2 matched groups of AD patients. METHODS: Nineteen pairs of patients with mild to moderate AD undergoing SPECT with either 99mTc-HMPAO or (99m)Tc-ECD were retrospectively selected in a Memory Clinic. Patients were matched for sex, age (+/-3 years) and the Mini-Mental State Examination score (+/-2 points) with a case-control procedure, thus obtaining 2 well-matched groups. The score on the Grober-Buschke selective reminding test (SRT) was correlated with SPECT in each group by means of statistical parametric mapping 99 (height threshold: P<0.01). RESULTS: (99m)Tc-HMPAO SPECT yielded 3 significant correlation clusters involving inferior and middle frontal gyri, para-hippocampal gyrus and putamen in the right hemisphere; the middle and superior temporal gyri, insula and claustrum in the left hemisphere. (99m)Tc-ECD gave a significant cluster of correlation in left postcentral gyrus and inferior parietal lobule. CONCLUSION: (99m)Tc-HMPAO SPECT correlation sites seem more consistent than (99m)Tc-ECD ones with the neurophysiological models of verbal memory, as designed both in normal individuals and in pathological conditions. The demonstration of such relevant differences introduces a source of variability among studies performed with either of the 2 compounds, which must be considered when interpreting results.

Aged↗
PubMed2006

The Von Restorff effect in ageing and Alzheimer's disease.

The purpose of the study was to evaluate the Von Restorff effect in normal ageing and in Alzheimer's disease (AD). A shortened paradigm was administered to three groups of subjects: young volunteers, elderly volunteers and patients with early-stage AD (MMSE>20). Each subject was presented with 25 lists of 10 words each, the target word appearing in double font size. A free recall phase followed the presentation of each list; after completion of the battery, a size recognition test was administered and subjects were inquired regarding the strategy employed and perception of target words. The total number of recalled words differed significantly among the three groups (young volunteers 144.4+/-38.6, elderly volunteers 86.5+/-17.6, patients 44.2+/-14.6). A significant difference in percentage of recall was found between target and non-target words in young (60.0+/-13.8% vs. 45.7%+/-15.0%, p<0.001) and in elderly (31.2+/-11.4% vs. 20.2+/-6.9%, p<0.001) volunteers, but not in patients (10.7+/-6.9% vs. 11.8+/-7.3%). The present study highlights that the Von Restorff effect can be detected in healthy elderly subjects, and that it is significantly reduced in patients in the early stage of AD. On the basis of the findings of the present study it is not possible to disentangle the contribution of visual-perceptual and encoding impairment, both of them potentially contributing to the observed reduction.

Adult↗
PubMed2005

Global cognitive impairment should be taken into account in SPECT-neuropsychology correlations: the example of verbal memory in very mild Alzheimer's disease.

PURPOSE: To examine the impact of severity of global cognitive impairment on SPECT-neuropsychology correlations, we correlated a verbal memory test with brain perfusion in patients with very mild Alzheimer's disease (AD), taking into account the Mini-Mental State Examination (MMSE) score as an index of global cognitive impairment. METHODS: Twenty-nine outpatients (mean age 78.2+/-5.5 years) affected by very mild, probable AD underwent brain SPECT with 99mTc-ethylcysteinate dimer and a word list learning test. SPM99 was used for voxel-based correlation analysis after normalisation to mean cerebellar counts (height threshold: p<0.01). In a first analysis, only age and years of education were inserted as nuisance covariates, while in a second analysis the MMSE score was inserted as well. RESULTS: In the first analysis, two clusters of significant correlation were found in both hemispheres, mainly including regions of the right hemisphere, such as the inferior parietal lobule, the middle temporal gyrus and the posterior cingulate. Significant correlation in the left hemisphere was observed in the lingual lobule, the parietal precuneus and the posterior cingulate. After taking into consideration the MMSE, the largest cluster of correlation was found in the left hemisphere, including the parietal gyrus angularis, the posterior cingulate and the middle temporal gyrus. CONCLUSION: The wide differences observed between the correlations achieved with and without taking into account the MMSE score indicate that severity of global cognitive impairment should be considered when searching for brain perfusion-neuropsychology correlations. In the present case, this strategy resulted in correlations that more closely matched neuropsychological models of verbal memory deficit.

Aged↗
PubMed2005

White matter hyperintensities on brain magnetic resonance in systemic sclerosis.

OBJECTIVE: To evaluate the brain status of patients with systemic sclerosis (SSc). METHODS: Fourteen female patients with SSc aged 24-74, with a disease duration of 1-12 years and without other relevant systemic diseases, were enrolled. All patients and an age matched female control group (CG) of 14 clinically normal subjects, underwent brain magnetic resonance examination at 1.5 T; spin echo proton density weighted images were evaluated. Mann-Whitney U and Spearman rank correlation tests were used for statistical analysis. RESULTS: 170 white matter hyperintensities >/=2 mm in diameter were counted in the patient group (range 0-75, mean 12.1, median 4.5), only 13 in the CG (0-2, 0.9, 1, respectively), with a significant difference (p = 0.011). Moreover, 208 white matter hyperintensities <2 mm were found in the patient group (0-38, 14.9, 8, respectively), only 31 in the CG (0-7, 2.0, 1, respectively), with a significant difference (p = 0.006). No statistically significant correlation between the number of hyperintensities and either patient's age or disease duration was observed. CONCLUSION: White matter hyperintensities are more common in patients with SSc than in a CG. These findings might be related to obliterative microvascular processes due to the disease. Early brain involvement in patients with SSc may occur.

Adult↗
PubMed2004

Subcortical nodular heterotopia: a functional MRI and somatosensory evoked potentials study.

Subcortical nodular heterotopia (SNH) associated with refractory epilepsy may be surgically treated, and a positive outcome can be expected following the complete excision of the malformed tissue. Recent functional neuroimaging studies have suggested the possible functional relevance of cerebral malformations, and may make it possible to improve presurgical planning, thus allowing extended resections and minimising post-operative deficits. We here report the case of a 19-year-old man with epilepsy and a giant SNH associated with diffused abnormal gyrations of the right temporal-parietal regions. Cortical functional organisation was investigated by means of functional magnetic resonance imaging (MRI) during sensory and motor tasks, and somatosensory evoked potentials. The results revealed enlarged and displaced motor and sensory cortical areas with heterotopic tissue functional activation. The relevance of these findings is discussed in the light of the possible surgical treatment of drug-refractory epilepsy associated with cerebral malformations: surgical treatment based on conventional MRI studies alone, without taking the functional nature of dysplastic tissues into account, may lead to considerable side effects.

Adult↗
PubMed2003

Psychological and social aspects in management of Alzheimer's patients: an inquiry among caregivers.

A survey in the cities of Genoa and Savona (Italy) was performed to examine stress levels in caregivers of patients with Alzheimer's disease in the context of a project of the Italian Ministry of Health named Cronos. It offered free anticholinesterase inhibitor therapy to patients who addressed dedicated Neurological Units; in this occasion caregivers could be invited to express the main difficulties encountered in managing demented people during an interview conducted by health personnel of the Neurophysiology Service. Caregivers were mainly women, daughters or spouses, with a medium educational level, retired, housekeepers, employees or teachers; they claimed a lowering of economic standard of living of the family owing to extra expenses for assistance. Satisfaction was expressed towards specialists, while support by general practitioners and other sanitary services was usually lacking and money contribution from the government or territorial services was considered inadequate. From the emotional point of view, caregivers claim loss of free time, friendships and hobbies, and feel isolated in the social context; sometimes the patient's death is thought of as a solution. A strong need for information and support is clearly emerging and any further interventions should take these requirements into consideration.

Aged↗
PubMed2002

Duplex scanning of neck vessels: need for extending the consensus on indications.

We studied the percentage and distribution of appropriate indications for duplex scanning of neck vessels in an outpatient population. A total of 650 consecutive outpatients sent by their general practitioner (GP) or a specialist for duplex scanning of epi-aortic arterial vessels were studied. The aim was to verify the percentage of appropriate (APR) an inappropriate (INAPR) indications for the examination, according to the current literature. After analysis of indications as reported by GPs or specialists and a brief anamnestic examination, 77% of patients were found to have had one or more APR and 23% of patients had none. Analysis of severity of atheromasic lesions between the two groups showed that patients with APR had significantly ( p<0.001, chi-square test) more severe lesions than patients with INAPR. In more detail, no patient with INAPR had severe (>60%) stenosis while 6.4% of patients with APR had severe stenosis. Moreover, the percentage of normal examinations or intima-media thickness only was 32.5% in patients with INAPR but fell to 17.2% in patients with APR. In the entire group, women were more represented than men even after consideration of the natural prevalence of female gender in the local population. Among inappropriate indications for the examination, isolated dizziness or vertigo, syncope and tinnitus were the most frequent. Continuous medical education is needed to reduce inappropriate indications and thus to find solutions, although partial, to shorten the waiting lists that have become an urgent problem for the public health systems of several Western countries. However, this appears to be difficult challenge, as experiments conducted on this issue by other researchers only gave transient positive results.

Aged↗
PubMed2002

Comparison of the TriTrac-R3D accelerometer and a self-report activity diary with heart-rate monitoring for the assessment of energy expenditure in children.

Determining total energy expenditure (EE) in children under free-living conditions has become of increasingly clinical interest. The aim of this study was to compare three different methods to assess EE triaxial accelerometry (TriTrac-R3D; Professional Products, Division of Reining International, Madison, WI, USA), activity diary and heart-rate (HR) monitoring combined with indirect calorimetry (IC). Twenty non-obese children and adolescents, aged 5.5 to 16.0 years, participated in this study. Results from the three methods were collected simultaneously under free-living conditions during the same 24 h schoolday period. Neither activity diary (5904 (sd 1756) kJ) nor the TriTrac-R3D (6389 (sd 979) kJ) showed statistical differences in 24 h total EE compared with HR monitoring (5965 (sd 1911) kJ). When considering different physical activity (PA) periods, compared with HR monitoring, activity diary underestimates total EE during sedentary periods (P<0.001) and overestimates total EE and PA-EE during PA periods (P<0.001) because of the high energy cost equivalence of activity levels. The TriTrac-R3D, compared with HR monitoring, shows good agreement for assessing PA-EE during PA periods (mean difference +0.25 (sd 1.9) kJ/min; 95 % CI for the bias -0.08, 0.58), but underestimates PA-EE and it does not show good precision during sedentary periods (-0.87 (sd 1.4) kJ/min, P<0.001). Correlation between the vector magnitude generated by the TriTrac-R3D accelerometer and EE of activities derived from HR monitoring is high. When compared with the HR method, the TriTrac-R3D and activity diary are not systematically accurate and must be carefully used for the assessment of children's EE depending on the purpose of each study.

Adolescent↗
PubMed2002

Brain functional involvement by perfusion SPECT in systemic sclerosis and Behçet's disease.

Involvement of the central nervous system is frequent in systemic immune-mediated diseases, such as systemic lupus erythematosus, Behçet's disease (BD), and systemic sclerosis (SSc). Structural brain examinations, such as computed tomography and magnetic resonance imaging, may be useful in diagnosing and following-up these cerebral syndromes in some cases, but they are more often inconclusive. Single photon emission computed tomography (SPECT) with perfusion tracers is a powerful method that can disclose brain involvement in many clinical situations, even in patients with subtle neurological symptoms. In fact, perfusion tracers can disclose regional hypoperfusion caused by both ischemia due to vascular narrowing and neuronal metabolic derangement due to direct neuronal damage. The latter phenomenon occurs because the blood flow to the brain is strictly regulated by metabolic demands, so that hypometabolism is reflected by hypoperfusion in most instances. SPECT findings in 42 mainly neurologically asymptomatic patients with SSc and in eight mainly neurologically symptomatic patients with BD are reported. SPECT was shown to be very sensitive and disclosed brain functional deficits in approximately half of SSc patients without neurological complaints and in all patients with BD, who had various neurological symptoms but usually inconclusive structural brain examinations.

Aged↗
PubMed2002

Carotid atherosclerosis in patients with rheumatoid arthritis: a preliminary case-control study.

A preliminary study was undertaken to investigate the severity of atherosclerotic lesions of neck arteries in patients with rheumatoid arthritis (RA) in comparison with matched controls. The working hypothesis derives from the recent view that the atherosclerotic plaque is essentially an inflammatory lesion. Thus, patients affected by a chronic inflammatory disease, such as RA, might show acceleration of atherosclerosis despite treatment with anti-inflammatory drugs. In 19 patients with RA the prevalence of atherosclerosis of internal carotid arteries, as seen on high-resolution duplex-scanning of neck arteries, was significantly (p < 0.05) higher than in 19 controls, whereas no significant difference was found for the other arteries. Factors underlying this finding are not known; increased levels of homocysteine and other thiol compounds that may enhance atherosclerosis in RA patients deserve further investigation. Moreover, more specific factors of RA are currently being investigated. In fact, immune complexes fixing C1q bind to endothelial receptors, thus triggering an upregulation of adhesion molecules, such as E-selectin and intercellular and vascular cell adhesion molecules 1, on the endothelium surface.

Aged↗
PubMed2002

Electropherotypes of rotaviral RNA from cases of infantile diarrhea in Uruguay.

Electropherotypes of human rotavirus isolates from infants with acute diarrhea belonging to two populations with different clinical features were determined. Thirteen electropherotypes were identified in total 69 isolates; 46 (66.6%) isolates had long RNA migration patterns and 23 (33.3%) isolates had short migration pattern. One of the long-pattern electropherotypes (47.82% of the total electropherotypes) was predominant. It was detected in both populations almost throughout the whole period of the study, while other electropherotypes were found only occasionally. The co-circulation of long and short electropherotypes was not frequent.

Diarrhea, Infantile↗
PubMed2001

Measurement of ultrafast ionization dynamics of gases by multipulse interferometric frequency-resolved optical gating.

Ultrafast ionization dynamics of femtosecond laser-irradiated noble and simple diatomic gases were studied using a novel two-color time-domain technique which eliminated significant complications seen in past experiments. Ultrafast depletion of the probing laser pulse was observed strictly coincident with the ionization front and attributed to a previously unobserved nonlinear frequency mixing via the transverse plasma current [F. Brunel, J. Opt. Soc. Am. B 7, 52 (1990)]. Good quantitative agreement of the measured single-atom ionization rates with Ammosov-Delone-Krainov rates was found, except for O (2) which showed a 200x smaller rate.

Journal Article↗
PubMed2001

Ultrafast dynamics of electron thermalization in gold.

Time-resolved surface second-harmonic generation (SHG) is used to probe electron relaxation processes in gold following intense laser excitation at 1.55 eV. For the first time, an electron temperature ( T(e)) dependent enhancement in the SHG signal is clearly observed at T(e) above 0.7 eV, which is shown to relate to the thermalization of nonequilibrium hot electrons. Therefore, the relaxation dynamics of the transient nonequilibrium electrons in the high T(e) regime is directly resolved by monitoring the time evolution of the SHG signal.

Journal Article↗
PubMed2001

Relationships between cortisol, dehydroepiandrosterone sulphate and insulin-like growth factor-I system in dementia.

Changes in the hypothalamus-pituitary-adrenal axis (HPAA) function, entailing elevated cortisol circulating titres, occur in aging and in some neurological conditions, such as Alzheimer's disease (AD). Excess cortisol has neurotoxic effects which affect hippocampal neurones. Dehydroepiandrosterone sulphate (DHEAS) has an antiglucocorticoid activity and neuroprotective effects, but its levels decrease with aging. Glucocorticoids influence the production of insulin-like growth factor-I (IGF-I) and modify its systemic and neurotrophic biological activity by inducing changes in IGF-binding proteins (IGFBPs). We looked for relationships between cortisol, DHEAS levels, and IGF-I - IGFBPs system in AD. Cortisol, DHEAS and GH levels at 02:00, 08:00, 14:00, 20:00 h, basal IGF-I, IGFBP-1 and IGFBP-3 levels were determined by RIAs or IRMA in 25 AD patients, aged 58-89 yr, and in 12 age-matched healthy controls. AD subjects had higher cortisol, lower DHEAS levels and increased cortisol/DHEAS ratio (C/Dr) than controls. In AD cases, total IGF-I, IGFBP-3, and IGF-I/IGFBP ratios were significantly lowered, while IGFBP-1 levels were significantly higher than in controls. We found a significant inverse correlation between IGF-I and IGFBP-3 levels vs C/Dr, and between both IGF-I/IGFBPs ratios vs mean cortisol levels. IGFBP-3 correlated directly with DHEAS. Cortisol was directly and IGF-I inversely correlated with cognitive impairment. In AD patients we found that alterations in HPAA function and elevated C/Dr are related to lowered total and free IGF-I levels. These findings and their relationship to cognitive impairment suggest that changes in hormonal set-up might influence the clinical presentation of the disease.

Adrenal Glands↗
PubMed2001

Left ventricular function impairment in pregnancy-induced hypertension.

The changes induced by transient hypertension on cardiac structure and function are unclear. Pregnancy-induced hypertension offers a natural and spontaneous model of this condition. To assess the potential of echocardiographic Doppler to unmask left ventricular function impairment, we studied 28 women aged 26.4 +/- 7.2 years with pregnancy-induced hypertension defined as blood pressure higher than 140/90 mm Hg in the third trimester of pregnancy without a history of hypertension. Twenty normal pregnant women, aged 27.5 +/- 6.4 years, were the controls. Left ventricular diastolic diameter, fractional shortening, E velocity, A velocity, E/A ratio, isovolumetric relaxation time (IRT), isovolumetric contraction time (ICT), ejection time (ET), and the combined index of myocardial performance (Tei index = IRT + ICT/ET), were calculated by echocardiography Doppler 2 to 4 days postpartum. There were statistically significant differences between groups in the following parameters: E/A ratio: 1.3 +/- 0.3 in pregnancy-induced hypertension v 1.5 +/- 0.3 in normal pregnant women (P < .05), IRT: 104 +/- 14 msec v 84 +/- 7 msec (P < .000), and the Tei index: 0.51 +/- 0.15 v 0.35 +/- 0.04 (P < .00), respectively. According to this data pregnancy-induced hypertension evaluated 2 to 4 days after delivery showed left ventricular dysfunction, mainly diastolic. The IRT and the Tei index are the most useful echocardiographic parameters to unmask left ventricular dysfunction in pregnancy-induced hypertension.

Adolescent↗
PubMed2001

Description and identification of difficulties arising from the application of a cleaning process in operating conditions for the treatment of components used on liquid metal fast reactors (LMFR). A technical designed approach to avoid these situations.

The cleaning process is one of the major maintenance operation for liquid metal fast reactors (LMFRs), both in operation and in their decommissioning stage. Russian and French cleaning processes are briefly described, including problems which have arisen during the processes. It appears that the cause of these problems is always connected to bad draining of the component, resulting in a vigorous reaction between vapour or liquid water and the bulk of sodium. From this discussion, the paper makes major recommendations for the efficient and safe cleaning of sodium wetted components, and proposes several processes which should be developed in order to deal with difficult situations, for example the removal of large amounts of undrainable sodium.

Chemical Precipitation↗
PubMed2001

Clinical correlative evaluation of an iterative method for reconstruction of brain SPECT images.

BACKGROUND: Brain SPECT and PET investigations have showed discrepancies in Alzheimer's disease (AD) when considering data deriving from deeply located structures, such as the mesial temporal lobe. These discrepancies could be due to a variety of factors, including substantial differences in gamma-cameras and underlying technology. Mesial temporal structures are deeply located within the brain and the commonly used Filtered Back-Projection (FBP) technique does not fully take into account either the physical parameters of gamma-cameras or geometry of collimators. In order to overcome these limitations, alternative reconstruction methods have been proposed, such as the iterative method of the Conjugate Gradients with modified matrix (CG). However, the clinical applications of these methods have so far been only anecdotal. The present study was planned to compare perfusional SPECT data as derived from the conventional FBP method and from the iterative CG method, which takes into account the geometrical and physical characteristics of the gamma-camera, by a correlative approach with neuropsychology. METHODS: Correlations were compared between perfusion of the hippocampal region, as achieved by both the FBP and the CG reconstruction methods, and a short-memory test (Selective Reminding Test, SRT), specifically addressing one of its function. A brain-dedicated camera (CERASPECT) was used for SPECT studies with 99mTc-hexamethylpropylene-amine-oxime in 23 consecutive patients (mean age: 74.2 +/- 6.5) with mild (Mini-Mental Status Examination score > or =15, mean 20.3 +/- 3), probable AD. Counts from a hippocampal region in each hemisphere were referred to the average thalamic counts. RESULTS: Hippocampal perfusion significantly correlated with the MMSE score with similar statistical significance (p < 0.01) between the two reconstruction methods. Correlation between hippocampal perfusion and the SRT score was better with the CG method (r = 0.50 for both hemispheres, p < 0.01) than with the FBP method (r = 0.37 and 0.43, respectively for the right and left hemisphere, p < 0.05 and p < 0.02). The bootstrap procedure showed that such correlation indexes were statistically different both in the right (p < 0.01) and in the left (p < 0.05) hemisphere. CONCLUSION: These results are interpreted as a better performance of the CG reconstruction method in correctly detecting counts from hippocampal ROI. By using the same gamma-camera or collimator, alternative methods for brain SPECT reconstruction may improve quality of data and then help SPECT diagnostic accuracy.

Aged↗