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G F Busatto

Publications and source records attributed to G F Busatto.

24 records · Page 2Linked to original sources
PubMed1995

In vivo imaging of GABAA receptors using sequential whole-volume iodine-123 iomazenil single-photon emission tomography.

Using a brain-dedicated triple-headed single-photon emission tomography (SPET) system, a sequential whole-volume imaging protocol has been devised to evaluate the regional distribution of iodine-123 iomazenil binding to GABAA receptors in the entire brain. The protocol was piloted in eight normal volunteers (seven males and one female; mean age, 24.8 +/- 3.9 years). The patterns obtained were largely compatible with the known distribution of GABAA receptors in the brain as reported in autoradiographic studies, with cerebral cortical regions, particularly the occipital and frontal cortices, displaying the highest 123I-iomazenil uptake. Measures of time to peak uptake and tracer washout rates presented with the same pattern of regional variation, with later times to peak and slower washout rates in cortical regions compared to other brain areas. Semiquantitative analysis of the data using white matter/ventricle regions as reference demonstrated a plateau of specific 123I-iomazenil binding in neocortical and cerebellar regions from 60-75 min onwards. These data demonstrate the feasibility of sequential, dynamic whole-volume 123I-iomazenil SPET imaging. The protocol may be particularly useful in the investigation of neuropsychiatric conditions which are likely to involve more than one focus of GABA abnormalities, such as anxiety disorders and schizophrenia.

Adult↗
PubMed1995

Dopamine D2 receptor blockade in vivo with the novel antipsychotics risperidone and remoxipride--an 123I-IBZM single photon emission tomography (SPET) study.

Risperidone and remoxipride are recently introduced atypical antipsychotics, with clinical efficacy comparable to that of classical antipsychotics but lower propensity to induce extrapyramidal side effects (EPS). It is unclear whether these properties relate to weak dopamine D2 receptor blockade in vivo, as has been suggested for the archetypal atypical antipsychotic clozapine. We have used 123I-IBZM single photon emission tomography (SPET) to characterize the patterns of striatal D2 receptor binding in vivo in DSMIII-R-diagnosed schizophrenic and schizo-affective patients treated with either risperidone (n = 6) or remoxipride (n = 4) but predominantly EPS free. These groups were compared to age- and BPRS- matched subjects from a previously reported D2 receptor binding database of patients treated with clozapine (n = 10) and classical antipsychotics (n = 10). Patients on risperidone and remoxipride had high levels of D2 receptor blockade, comparable to those of patients on classical antipsychotics, and significantly greater than those obtained with clozapine-treated patients (risperidone versus clozapine, P < 0.005; remoxipride versus clozapine, P < 0.025). These results suggest high levels of striatal D2 receptor occupancy in association with remoxipride and risperidone treatment and argue against modest D2 antagonism as the explanation for the low incidence of EPS associated with these drugs.

Adult↗
PubMed1995

Regional cerebral blood flow in obsessive-compulsive disordered patients at rest. Differential correlates with obsessive-compulsive and anxious-avoidant dimensions.

BACKGROUND: We tested whether cortical and subcortical regional cerebral blood flow (rCBF) differs between patients with obsessive-compulsive disorder (OCD) and healthy controls. We then explored the relationship between rCBF and OCD mental state. METHOD: Thirty out-patients from the Maudsley Hospital with OCD as defined in DSM-III-R were scanned at rest using brain-dedicated, high-resolution, single photon emission tomography. RCBF was measured as uptake of 99mTc-HMPAO in 15 regions of interest and compared with rCBF data in 30 healthy people matched for age, sex and handedness. Symptom ratings were obtained using standard measures on the scanning day. Principal components factor analysis identified two distinct clinical dimensions: obsessive-compulsive (OC) and anxious-avoidant (AA). These were correlated with patients' rCBF measurements, using Spearman's rank correlation coefficient, and multiple regression coefficients calculated. RESULTS: We found significant reductions in rCBF measurements of OCD patients compared with resting, healthy controls (F = 1.92, P = 0.04) in seven brain regions: the right and left superior frontal cortex, right inferior frontal cortex, left temporal cortex, left parietal cortex, right caudate nucleus and right thalamus. Regional differences were not secondary to generalised reduction in patients' brain perfusion. Reduced blood flow to the right inferior frontal cortex correlated significantly with illness severity (r = 0.37, P = 0.02). There was no relationship with age, age-of-onset, sex, handedness, depression or medication status. OC clinical dimension, concerning obsessions, compulsions and low mood, was significantly negatively correlated with left inferior frontal, medial frontal and right parietal rCBF. AA dimension, concerning anxiety and avoidance, was significantly positively associated with left and right superior frontal, right inferior frontal, medial frontal cortical, and right and left caudate and thalamic rCBF. CONCLUSIONS: rCBF differs significantly between resting OCD patients and healthy controls, and separate clinical dimensions are associated with functionally distinct rCBF patterns.

Adult↗
PubMed1994

Regional cerebral blood flow (rCBF) in schizophrenia during verbal memory activation: a 99mTc-HMPAO single photon emission tomography (SPET) study.

Regional cerebral blood flow (rCBF) was investigated in a group of medicated DSM-III-R schizophrenic patients and age, sex and handedness matched normal volunteers using a split-dose 99mTc-HMPAO Single Photon Emission Tomography (SPET) protocol. Measures were taken during the performance of a verbal memory task aimed at activating the left medial temporal lobe, a region repeatedly suggested to be structurally abnormal in schizophrenia. In normal subjects, the performance of the task was associated with significant rCBF increases in the left medial temporal, left inferior frontal and anterior cingulate cortices, and right cerebellum. Despite their significantly poorer performance on the memory task, the degree of medial temporal activation measured in the schizophrenic patients was not significantly different from that found in the control group. This finding suggests that memory deficits in schizophrenia do not necessarily imply failure to activate the left medial temporal lobe as assessed by 99mTc-HMPAO SPET.

Adult↗
PubMedDate not supplied

Neuroreceptor mapping with in-vivo imaging techniques: principles and applications.

Functional imaging techniques can now be used to map neuroreceptor distribution in the living human brain. This permits direct investigation of neurochemical abnormalities in neuropsychiatric disorders and opens possibilities for the development of more specific pharmacological treatments for these conditions. This article reviews the basic principles of neuroreceptor imaging and recent research findings in the area.

Alzheimer Disease↗