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Biomedical subjects

I Podreka

Publications and source records attributed to I Podreka.

At least 37 records · Page 2Linked to original sources
PubMed1995

D2 receptor blockade by flunarizine and cinnarizine explains extrapyramidal side effects. A SPECT study.

Twenty-six patients under treatment with the calcium channel blockers flunarizine (Fz) or cinnarizine (Cz) were examined-with single-photon emission computed tomography using [123I]iodobenzamide as a ligand. The striatal dopamine D2 receptor-binding potential was determined and found to be reduced by 14 to 63% (39.5 +/- 15.0%; p < 0.0001) in patients compared with age-matched control values. This reduction was larger in 12 patients with extrapyramidal symptoms and was only slowly reversible after discontinuation of treatment. Patients treated for > 6 months had significantly larger reductions than patients treated for a shorter period. Parkinsonian symptoms were only seen in patients older than 50 years. Our findings prove a neuroleptic-like action of Fz and Cz, which seems to be the major reason for their extrapyramidal side effects. Older age and long-term treatment are predisposing factors for these effects.

Adult↗
PubMed1995

Chronic relapsing polyradiculoneuropathy in IgG lambda monoclonal gammopathy of undetermined significance (MGUS)--complete remission following carmustine treatment.

A previously healthy 43 year-old female developed IgG lambda monoclonal gammopathy of undetermined significance (MGUS) and ascending sensorimotor polyradiculoneuropathy which relapsed 11 times within 2 years. Marked improvement was noted repeatedly after plasmapheresis. However, on each occasion symptoms and signs of polyradiculoneuropathy recurred almost exactly 3 weeks after plasma-pheresis. Following 6 weeks of treatment with carmustine (70 mg/week), nearly complete recovery was established, which has persisted up to now (82 months after the end of therapy). The close temporal correlation between clinical relapse and recurrence of the IgG paraprotein and its permanent absence in stable clinical remission after carmustine treatment suggest a causal relationship between the paraprotein and the polyradiculoneuropathy. However, further studies are required to confirm this observation, as well as the efficacy of carmustine therapy.

Adult↗
PubMed1995

Technetium-99m-HMPAO SPECT imaging of cerebral blood flow during REM sleep in narcoleptics.

UNLABELLED: This study was performed to demonstrate global and regional cerebral blood flow (rCBF) changes during rapid eye movement (REM) sleep in six patients with narcolepsy using SPECT and 99mTc-HMPAO. METHODS: Global and hemispheric HMPAO uptake as well as regional (RI) and asymmetry indices were estimated and compared between polysomnographically verified sleep onset (SO)REM and wakefulness. RESULTS: The estimated global HMPAO uptake did not differ between the two conditions indicating a similar overall cortical activity. During (SO)REM sleep, hemispheric HMPAO uptake as well as calculated RI, especially in the supratemporal plane, were significantly higher on the right side than contralateral. This indicates an initially right-sided cerebral activation and a special involvement of the right, nondominant hemisphere during dreaming which is responsible for visual-spatial perceptions. Furthermore, increased RI in superior parietal regions during sleep were evident and were explained by an activation of associative areas. In thalamic regions, decreased RI were found during sleep, which may reflect thalamic dysfunction. CONCLUSION: A definite assignment of these CBF alterations to (SO)REM sleep might be problematic because of unstable boundaries between sleep stages in narcolepsy. On the other hand, specificity of such CBF changes for narcolepsy requires further study.

Adolescent↗
PubMed1994

Iodine-123-IBZM-SPECT: studies in 15 patients with pituitary tumors.

Single photon emission computerized tomography (SPECT) using the Iodine 123 labeled dopamine D2 receptor antagonist S(-)Iodobenzamide [S (-)IBZM] was performed in 15 patients with pituitary tumors. Among them there were five prolactinoma patients with macroadenoma and two acromegalic patients with macroadenoma. Specific binding in the area of the adenoma was only observed in one subject, a macroprolactinoma patient, who was responsive to dopaminergic treatment. None of the other patients, among them one macroprolactinoma patient responsive to dopaminergic treatment showed specific binding in the area of the tumor. IBZM-binding in the striatum was found to be significantly lower in the group of pituitary tumor patients as compared to controls. The results show that D2 receptors in pituitary adenomas can be visualized using SPECT. However, the sensitivity of IBZM-SPECT appears to be too poor to visualize PRL- and GH- secreting macroadenomas in general.

Adenoma↗
PubMed1994

Anterior frontal cortex and the effect of proactive interference in word pair learning--results of Brain-SPECT.

Technetium-99m-HMPAO-Brain-SPECT was performed twice in each of 12 right-handed students. The control condition was a standard word pair learning task. In the experimental condition, subjects had to overcome the detrimental effect that older memories exerted on the acquisition of new information (controlling proactive inhibition): they were presented with taxonomically similar words, which could easily be mixed up, and which reappeared in each list, but in different pairings. Results revealed an increase in right anterior frontal flow indices with the experimental condition. These results parallel the observed increase in negative event-related DC potential shifts. UHL et al. [J. cognit. Neurosci. 2, 373, 1990] recorded at frontopolar (Fp3, Fp4) scalp projections, although the extent of modulation was much higher for DC potentials (100%) than it was for SPECT (3%) thus suggesting different sensitivity.

Adult↗
PubMed1994

Dopamine D2 receptor blockade and antimigraine action of flunarizine.

We studied in vivo the influence of flunarizine on dopamine D2 receptors and investigated whether dopamine D2 receptor blockade is involved in its antimigraine action. Eleven migraine patients, treated with flunarizine, 10 mg per day, underwent single photon emission computer tomography (SPECT) using [123I] labeled iodobenzamide, a ligand with high affinity and high specificity for D2 receptors. There was a reduction of the dopamine D2 receptor binding potential in all patients compared to age-matched controls. The efficacy of flunarizine in migraine prophylaxis failed to correlate with the degree of the dopamine D2 receptor blockade. The antimigraine action of flunarizine may not involve antidopaminergic mechanisms.

Adult↗
PubMed1993

SPECT imaging of dopamine and serotonin transporters with [123I]beta-CIT. Binding kinetics in the human brain.

Single photon emission computerized tomography (SPECT) studies in non-human primates have previously shown that the cocaine derivative [123I]-2-beta-carbomethoxy-3-beta-(4-iodophenyl)-tropane ([123I]beta-CIT) labels dopamine transporters in the striatum and serotonin transporters in the hypothalamus-midbrain area. Here, we report on the regional kinetic uptake of [123I]beta-CIT in the brain of 4 normal volunteers and 2 patients with Parkinson's disease. In healthy subjects striatal activity increased slowly to reach peak values at about 20 hours post injection. In the hypothalamus-midbrain area peak activities were observed at about 4 hours with a slow decrease thereafter. Low activity was observed in cortical and cerebellar areas. The striatal to cerebellar ratio was about 4 after 5 hours and 9 after 20 hours. In 2 patients with idiopathic Parkinson's disease striatal activity was markedly decreased while the activity in hypothalamus-midbrain areas was only mildly diminished. Uptake into cortical and cerebellar areas appeared to be unchanged in Parkinson's disease. Consequently, in Parkinson's disease the striatal to cerebellar ratio was decreased to values around 2.5 after 20 hours. These preliminary methodological studies suggest that [123I]beta-CIT is a useful SPECT ligand for studying dopamine and possibly also serotonin transporters in the living human brain.

Adult↗
PubMed1993

Role of PET and SPECT in the assessment of ischemic cerebrovascular disease.

Functional neuroimaging techniques such as positron and single-photon emission computed tomography (PET and SPECT) have contributed to our knowledge of pathophysiological changes in ischemic stroke. Determinations of cerebral blood flow (CBF), cerebral blood volume (CBV), and cerebral metabolic rate of oxygen (CMRO2) permit the discrimination of various compensatory mechanisms in occlusive vascular disease, where changes in the CBF/CBV ratio indicate a perfusional reserve and increases in the oxygen extraction fraction (OEF), a metabolic reserve, that prevent ischemic tissue damage during graded flow decreases. Early in the course of acute ischemia, CBF and CMRO2 below a certain threshold (approximately 12 ml/100 g/min and/or 65 mumol/100 g/min, respectively) indicate irreversible tissue damage, while preservation of CMRO2 with decreased flow resulting in increased OEF ("misery perfusion") suggests still viable tissue up to 48 h after the attack, which, however, turns into necrosis in most instances during the following period. In a few instances such tissues can survive, suggesting a potential for effective therapy. Transient ischemic attacks are caused by less severe regional flow disturbances and the consequent metabolic changes are not so significant. In these cases the impact of obstructive vascular changes on hemodynamic reserve can be evaluated by functional tests applying CO2 or acetazolamide. While the regional cerebral metabolic rate of glucose (rCMRglu) in early ischemia is often not coupled to flow or CMRO2 and might even be increased (nonoxidative glycolysis with consequent tissue lactacidosis), this variable is the best indicator of permanent impairment of tissue function. (ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Cranial MR imaging and cerebral 99mTc HM-PAO-SPECT in patients with subacute or chronic severe closed head injury and normal CT examinations.

Eighteen patients in the subacute or chronic state following severe closed head injury with normal cranial CT scans were examined by MR and 99mTc HM-PAO SPECT. Correlations were sought between these 2 imaging modalities and the clinical outcome, as defined by the Glasgow Outcome Scale (GOS) score. Both MR and SPECT revealed cerebral damage in all patients examined but structural and functional alterations did not coincide topographically in 64.9% of lesions. Nevertheless, complementary injury patterns suggesting poor recovery were found; cortical contusions and diffuse axonal injury (MR) in conjunction with cortical and thalamic hypoperfusion (SPECT) were noticed in 8 out of 12 patients with unfavorable outcome (GOS = III and IV). The synthesis of MR and SPECT information clearly enhanced the ability both to accurately assess posttraumatic brain damage and to improve patients' outcome prediction.

Adolescent↗
PubMed1993

Dopamine D2 receptor imaging and measurement with SPECT.

Only recently it has become possible to label and visualize dopamine D2 receptors in the living human brain using an [123I]labeled ligand and the SPECT technique. Iodobenzamide (S(-)IBZM) is a substance with high affinity and high specificity for D2 receptors and was used in controls and in patients with different extrapyramidal disorders. After the i.v. administration of 5mCi (185 MBq) of [123I] labeled S(-)IBZM data collection was performed with a rotating double head scintillation camera between 60 and 110 minutes. In a semiquantitative approach a ratio was calculated between mean counts/pixel in the striatum and a region in the lateral frontal cortex, which gives an index of receptor density. In a group of 21 controls this ratio is 1.73 +/- 0.09. A highly significant age-related decline is found in controls and in 57 patients with PD. PD patients without L-DOPA or dopamine agonist treatment do not differ from controls (1.72 +/- 0.09; n = 18), whereas patients under dopaminergic therapy show a significantly lower binding ratio (1.65 +/- 0.13; n = 39; p = 0.017) suggesting receptor downregulation. Comparing the striatum ipsi- and contralateral to clinical symptoms in 18 hemiparkinsonian patients shows slightly but significantly higher values on the contralateral side, indicating receptor supersensitivity (1.71 +/- 0.11 vs. 1.66 +/- 0.09; p = 0.0014). No correlation between D2 receptor binding and clinical stage, duration of disease or duration of dopaminergic therapy exists. Markedly reduced ratios are measured in 7 patients with progressive supranuclear palsy and multiple system atrophies and in 18 patients with Huntington's disease (1.40 +/- 0.09 and 1.37 +/- 0.12 respectively; p = 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Regional cerebral blood flow patterns related to verification of low- and high-imagery sentences.

Although several SPECT studies have shown left inferior occipital activation with visual imagery, the reliability of this finding remains doubtful. The present study replicated two conditions of a previous SPECT-study exploring rCBF in subjects verifying the correctness of low- and high-imagery sentences. As in the previous study, verification of high-imagery sentences was associated with higher flow rates in the left inferior occipital region and lower flow rates in the right anterior frontal region. By contrast, a bilateral increase of thalamic flow rates with imagery was not replicated, and there was a higher flow rate in the left inferior temporal region with low-imagery sentences which had not been found in the original study.

Adult↗
PubMed1992

Cerebral correlates of disturbed executive function and memory in survivors of severe closed head injury: a SPECT study.

Thirty six patients in the chronic stage after severe closed head injury were examined with tests of executive function, memory, intelligence, and functional capacities in daily living. Correlations were sought between test results and Tc-99m-HMPAO uptake of frontal, temporal, and thalamic regions assessed by SPECT. Neither the number of significant correlation coefficients between memory tests and regional uptake nor that between temporal uptake and tests exceeded chance. For the remaining tests, correlations to thalamic regions were stronger than those to the frontal regions, and those to right brain regions stronger than those to homologous left brain regions. Relationships of thalamic isotope uptake to neuropsychological performance may reflect the impact of diffuse brain damage and particularly of diffuse axonal injury on mental capacities.

Adult↗
PubMed1992

Behavioural and psychosocial sequelae of severe closed head injury and regional cerebral blood flow: a SPECT study.

Thirty six patients (31 male, 5 female) who had suffered severe closed head injury were re-examined at an average of 39.3 (SD 12.8, range 7-66) months after the injury. Behavioural symptoms were measured using the Giessen test. The relatives' reports were used for data analysis to ensure that results were valid. The neurophysical impairment subscale of the Glasgow assessment schedule was completed by two neurologists, and the number connection test was completed by each patient. The adjective mood scale was completed by each relative. All patients were investigated by single photon emission computerised tomography (SPECT). Exploratory factor analysis using the principal components method was carried out separately for SPECT results and psychological measures and correlations were sought between the resulting factors. Factor analysis of the data from the Giessen test identified social isolation, disinhibition, and aggressive behaviour as major components of post-traumatic personality changes; it indicates that these behavioural features are independent of the level of neurological and neuropsychological impairment, which loaded on a single independent factor. Relatives' psychic health seemed to be relatively resistant to physical and cognitive disability and was mainly affected by disinhibitive behaviour. The highest correlation was between frontal flow indices and disinhibitive behaviour (p less than 0.01): the severity of disinhibition increased with lower frontal flow rates. There was a significant but somewhat weaker correlation (p less than 0.05) between flow indices of the left cerebral hemisphere and social isolation. Low flow values of the right brain regions were related to aggressive behaviour (p less than 0.05). Neurological and cognitive impairment correlated negatively with the thalamus; worse neurological and cognitive performance indicate by raised scores on the neurophysical scale and on the number connection test was associated with low thalamic flow values. The results support the importance of lesion location in the production of post traumatic behavioural disorders.

Adolescent↗
PubMed1992

Basics and recommendations for brain SPECT. Task Group "Neurology" of the European Association of Nuclear Medicine.

In this article guidelines for single-photon emission computerized tomography (SPECT) of the brain are presented by the Task Group "Neurology" of the European Association of Nuclear Medicine (EANM). Under separate headings are discussed: the pathophysiologic principles of various brain diseases, pharmacokinetics and pharmacodynamics of various radiopharmaceuticals, physical principles of SPECT imaging, computerized data processing, clinical protocols and the evaluation of SPECT results.

Brain↗
PubMed1991

HM-PAO-SPECT in persistent vegetative state after head injury: prognostic indicator of the likelihood of recovery?

Management of patients presenting with traumatic persistent vegetative state (PVS) calls for extensive resources. The ability to predict whether or not a patient is likely to recover is a critical issue. In 12 patients with PVS admitted consecutively for early rehabilitation after head injury, pattern of brain activity was measured by 99mTc-hexamethyl-propylenamineoxime (99mTc-HM-PAO) brain SPECT (single photon emission computer tomography). All patients were re-investigated after a mean observation period of 3 years. A global reduction of cortical blood flow was a reliable predictor of poor long-term outcome, but the demonstration of only focal deficits did not reliably indicate a favourable outcome. Brain SPECT may help to improve outcome prediction in patients with traumatic PVS.

Adolescent↗