Characterization of the gamma-aminobutyric acid receptor system in human brain gliomas.

The properties of [3H]-gamma-aminobutyric acid [( 3H]GABA) binding were studied in biopsied specimens from normal human brain and from 18 cases of human brain gliomas, made up of 6 astrocytomas, 6 glioblastomas, 3 oligodendrogliomas, and 3 medulloblastomas. In fresh membranes obtained from normal gray and white matter one population of Na+-dependent GABA receptors was observed, while in the frozen Triton X-100-treated membranes two distinct populations of Na+-independent binding sites were detected. Specific GABA binding sites in brain gliomas were shown only in frozen Triton X-100-treated membranes. As in normal tissue, these receptors are Na+-independent and bind [3H]GABA with two distinct affinity components. The biochemical profiles of [3H]GABA binding to membranes obtained from different tumors of glial origin are quite similar and cannot be related to the degree of malignancy of the neoplasia.

Multiple forms of protein kinase from normal human brain and glioblastoma.

The biochemical characteristics of the protein kinase (PK; adenosine triphosphate-protein phosphotransferase, EC 2.7.1.37) isozymes in subcellular preparations from normal human brain cortex and glioblastoma were investigated after chromatography on diethylaminoethyl cellulose, and the following results have been obtained. Two major isozyme forms, eluted by 50 and 200 mM phosphate buffer, are present in both cytosol and membrane-derived preparations from cerebral cortex. Furthermore, these isozyme forms have properties similar to those referred to as type I and type II cyclic adenosine 3':5'-monophosphate-dependent PK. In these chromatographic isozymes, cyclic adenosine 3';5'-monophosphate is more active in stimulating the basal PK enzyme than is cyclic guanosine 3':5'-monophosphate. In glioblastoma, the PK activity from cytosol and particulate preparations is resolved by diethylaminoethyl cellulose in four peaks. In cytosol, the major portion of the enzyme is eluted with a 300 mM buffer (about 50% of the total basal PK activity) and is cyclic nucleotide dependent. On the contrary, in glioblastoma particulate, the PK enzyme is mainly eluted at 50 and 100 mM buffer; neither of these isozymes is cyclic nucleotide dependent. As for cytosol, only the particulate isozyme eluted at 300 mM buffer is strongly activated by cyclic nucleotides. Finally, in both glioblastoma subcellular preparations, only a type II cyclic adenosine 3':5'-monophosphate-dependent PK is present.

Stimulation of lymphocytes by cholinergic receptor in myasthenia gravis.

Lymphocytes from 13 myasthenic patients were incubated in vitro with membranes enriched in nicotinic cholinergic receptor obtained from Torpedo marmorata electric organ. When autologous serum was present in the incubation medium, the lymphocytes were highly stimulated. In contrast, no stimulation occurred when lymphocytes were cultured in presence of AB serum. These results suggest that an immune response against the Ach cholinergic receptor is present in myasthenic patients and give further support to the hypothesis that an autoimmune response against muscular receptors may be involved in Myasthenia Gravis pathogenesis.

Increased cytokine release from peripheral blood cells after acute stroke.

Cytokines interleukin (IL)-6 and tumor necrosis factor (TNF)-alpha can play pathogenetic or protective roles in stroke. They are increased in the brain after experimental ischemia and in the CSF of patients with stroke. However, their presence in the periphery is still controversial. To determine the source and time-course of cytokines in blood of stroke patients, IL-6 and TNF-alpha release from blood cells and serum levels were determined in 40 patients on days 1 through 2, 4, 10, 30, and 90 after stroke. Twenty healthy age-matched volunteers were used as controls. IL-6 and TNF-alpha release from stimulated blood cells was increased in stroke patients, compared to controls. A peak response (+224%) was observed at day 4 for IL-6, while TNF-alpha release was largely and significantly increased (about three-fold compared to controls) from day 1 to 2 until day 90 after stroke. The increase in IL-6 release was significantly higher in ischemic, compared to hemorrhagic strokes, at days 1 and 4. Circulating IL-6 was increased at each time point. The ischemic processes in the CNS induces a long-lasting activation of IL-6 and TNF-alpha production in peripheral blood cells, which are a major source of serum cytokines after stroke.

Hemiparkinsonism. A human model for studying dopaminergic supersensitivity.

The observation of a patient suffering from a parkinsonian syndrome, almost entirely expressed on the right side, and "on-off" attacks with rotatory movement of the trunk, led us to consider that the rotational model of animals may be reproduced in man. The symptoms presented by our patient may reflect a predominant degeneration in the nigrostriatal pathway of the left side. We suggest that his torsion behavior is due to hypersensitivity phenomenon of the dopaminergic receptors on this side.

Characterization of beta-adrenergic receptors on human cerebral microvessels.

Cerebral microvessels were separated and prepared from human brain cortex by albumin floatation and glass bead filtration. The binding of a specific beta-adrenergic antagonist, (125I) iodohydroxybenzylpindolol, to the microvessel preparation was characterized by high affinity, saturability, and stereospecificity. The presence of specific beta-adrenergic receptor sites in human cerebral microvessels supports the hypothesis of adrenergic regulation of the function of cerebral microvessels.

Treatment of Parkinson's disease with proglumide, a CCK antagonist.

Proglumide, a cholecystokinin antagonist, did not improve Parkinson's disease in a preliminary drug treatment trial.

Therapeutic experience with transdihydrolisuride in Huntington's disease.

Transdihydrolisuride is an ergot derivative with mixed agonist and antagonist effects on central dopamine receptors. We gave the drug orally (1 mg daily) to 10 patients with Huntington's disease. In seven patients, the chorea improved with no adverse effects during the study.

Increased glutamate in CSF and plasma of patients with HIV dementia.

BACKGROUND: Experimental evidence suggests that excitotoxicity might play a major role in HIV-induced neurodegeneration. However, few studies have investigated the role of endogenous glutamate in patients with HIV dementia. OBJECTIVE: To analyze CSF and plasma glutamate levels in 30 patients with AIDS with different dementia severity compared with 10 patients with other neurologic disorders, 11 healthy control subjects, and 10 patients with Alzheimer-type dementia. METHODS: CSF and plasma glutamate levels were measured by reverse-phase high-performance liquid chromatography followed by fluorometric analysis. RESULTS: Glutamate CSF levels were increased fivefold in the patients with HIV vs normal control subjects (p = 0.001), patients with Alzheimer-type dementia (p < 0.0001), and patients with other neurologic disorders (p < 0.01). CSF glutamate levels were also related to the degree of dementia (p < 0.02) and brain atrophy (p < 0.002). Plasma levels were also higher in the patients with HIV (p < 0.0001) but did not correlate with either clinical or imaging features. CONCLUSION: Increased CSF glutamate may originate within the CNS and may play a pathogenetic role in HIV dementia, thus supporting the treatment of these patients with glutamate receptor antagonists.

Cerebrospinal fluid levels of diazepam-binding inhibitor in neurodegenerative disorders with dementia.

We investigated CSF levels of diazepam-binding inhibitor (DBI), a recently discovered neuropeptide that allosterically modulates GABAergic transmission, in various neurodegenerative disorders with dementia (28 patients with Parkinson's disease, 10 with Alzheimer's disease, 7 with Huntington's chorea). We applied a battery of neuropsychological tests to determine the degree of dementia and to exclude the presence of mood alterations. CSF DBI levels were elevated in parkinsonian subjects with dementia and in patients with Alzheimer's disease, but decreased in Huntington's chorea patients. We hypothesize that modifications of CSF DBI levels may be related to a functional or structural alteration of the GABAergic system.

Distribution of a putative endogenous modulator of the GABAergic system in human brain.

Diazepam binding inhibitor (DBI) is a novel neuropeptide purified from rat, cow, and human brain that allosterically modulates GABAergic transmission by binding to benzodiazepine (BDZ)-recognition sites. Using a specific radioimmunoassay for human DBI, we investigated the distribution of this peptide in different brain areas. We characterized with high-pressure liquid chromatography the DBI immunoreactivity in brain tissue obtained by biopsy and autopsy; we detected one molecular species of DBI in both instances. The regional distribution of DBI in the human brain is similar to that observed in rat brain: high concentrations in cortical and limbic areas, cerebellum, and brainstem, and low concentrations in the basal ganglia. These data suggest a modulatory role for DBI in human brain.

Creutzfeldt-Jakob disease with a novel four extra-repeat insertional mutation in the PrP gene.

OBJECTIVE: To investigate the role of a short insertional mutation in the prion protein (PrP) gene (PRNP) in prion disease pathogenesis. BACKGROUND: The genetic forms of Creutzfeldt-Jakob disease (CJD) are associated with point or insertional mutations in PRNP. Whereas patients with five, six, seven, eight, and nine extra octapeptide repeats show an autosomal dominant pattern of inheritance and features of CJD, Gerstmann-Sträussler-Scheinker disease, or atypical dementia, patients with one, two, or four extra repeats have typical CJD and lack a family history of neurologic disorder. METHODS: A genetic, neuropathologic, and biochemical study was carried out in a 65-year-old patient with clinical features of sporadic CJD. RESULTS: A novel four extra-repeat insertional mutation of PRNP was found in the patient and in his 59-year-old healthy sister. The patient showed spongiosis, nerve cell loss, and gliosis associated with diffuse PrP immunoreactivity in the cerebral cortex, subcortical gray structures, and cerebellum. A peculiar aspect was the presence of focal PrP deposits in the basal ganglia and hypothalamus, superimposed to diffuse PrP immunoreactivity. The biochemical analysis revealed that both mutant and wild-type PrP participated in the pathologic process, and that the protease-resistant core of the altered PrP isoforms was distinct from that observed in sporadic, acquired, and other genetic forms of CJD. CONCLUSION: These findings support the view that the four extra-repeat insertion in PRNP is a pathogenic mutation with low penetrance rather than a benign polymorphism, and suggest that this mutation results in the formation of a distinct PrP conformer.

Decreased platelet glutamate uptake in patients with amyotrophic lateral sclerosis.

Decreased glutamate uptake and a loss of the astrocytic glutamate transporter EAAT2 (GLT-1) have been shown in spinal cord and motor cortex of patients with ALS. Because platelets express the three major glutamate transporter subtypes, including GLT-1, and possess a high-affinity glutamate uptake, the authors investigated glutamate uptake in platelets from patients with ALS and controls. A 43% reduction of high-affinity glutamate uptake rate (p < 0.0001) was observed in patients with ALS compared with normal controls and chronic neurologic disorder patients, suggesting a systemic impairment of glutamate uptake in ALS.

Effect of anticonvulsant drugs on peripheral benzodiazepine receptors of human lymphocytes.

Anticonvulsant drugs, such as carbamazepine, may exert some of their effects through peripheral benzodiazepine receptors (PBR), which are present in glial cells and regulate the synthesis of neurosteroids. PBR have also been demonstrated in human lymphocytes, where they might be used as peripheral markers of anticonvulsant drug effects. In the present paper we investigated the interaction of various antiepileptic drugs with PBR of human lymphocytes and evaluated possible effects of acute and chronic treatment with these drugs. At normal therapeutic concentrations, diazepam, carbamazepine and phenobarbital occupy respectively 70, 30 and 10% of PBR sites in human lymphocytes. Although no change of receptor density or affinity was observed after acute in vitro treatment, in epileptic patients chronically treated with carbamazepine, phenobarbital and valproic acid, PBR Bmax was increased with respect to controls and untreated epileptics. Since PBR of human lymphocytes may be affected by anticonvulsant drug treatment, we suggest that they might be involved in the immunological alterations reported in these patients and might be used as peripheral markers of drug effects on the central nervous system.

Characterization of peripheral benzodiazepine receptors in human blood mononuclear cells.

In the present study, peripheral-type benzodiazepine receptors in human circulating mononuclear cells were characterized, using [3H]PK 11195 as specific ligand. The specific binding was saturable, with a Bmax of 14 pmol/mg protein and a Kd of 7 nM. The pharmacological characterization, using different displacing drugs, indicated a mitochondrial type of peripheral benzodiazepine receptor since it was not coupled to the GABA receptor and was displaced by protoporphyrin IX. These data indicate that human circulating mononuclear cells possess benzodiazepine recognition sites, similar to non-neuronal receptors. The role of these receptors and possible modifications in different diseases need to be investigated.

Cyclandelate versus flunarizine. A double-blind study in a selected group of patients with dementia.

A double-blind, double-dummy clinical trial was conducted in which the efficacy of cyclandelate 1600 mg daily was compared with that of flunarizine 10mg daily in 40 patients (25 men and 15 women) with dementia of cerebrovascular origin. Parameters were assessed before treatment, and after 45 and 90 days of therapy. At 90 days, significant improvements were observed in patients given cyclandelate in measurements of P100 latency in the left eye, neurological impairment, dementia scores, ischaemia scores, Gottfries mental deterioration scale, Hamilton depression scores, short term visual memory, long term memory, Bender-Gestalt test and Koh's blocks test. In flunarizine recipients, improvements were observed in neurological impairment, ischaemia scores, Gottfries scale and Hamilton depression scores. Patients treated with cyclandelate showed significantly greater ameliorations in symptoms as assessed by the ischaemia scale, evoked visual potential, visual memory and Koh's block test compared with those given flunarizine. However, in none of the parameters was flunarizine superior to cyclandelate.

Risk factors for the development of severe cisplatin neurotoxicity.

Cisplatin sensory neuropathy is not equally severe in all patients and may progress even after drug withdrawal. A major goal in cisplatin chemotherapy would be the identification of early predictors of an unfavorable neurological outcome in order to adjust the schedules of administration. The final neurological outcome of 63 women treated with the same schedule of cisplatin (CDDP) was compared with the general demographic and oncological parameters and with the baseline neurological results. No definite association could be drawn between any of the parameters evaluated and peripheral neuropathy. Further studies are needed to investigate the individual factors which are at the basis of the remarkable variability of this severe side effect of CDDP.

Benzodiazepine-induced chemotaxis is impaired in monocytes from patients with generalized anxiety disorder.

Peripheral benzodiazepine receptors (PBR) modulate chemotaxis and cytokine production of monocytes and lymphocytes. Since PBR are decreased in animal models of stress and in patients with anxiety disorders, in the present study we analyze the ability of monocytes obtained from patients suffering from generalized anxiety to migrate towards chemoattracting benzodiazepines. In these patients, the benzodiazepine-induced chemotaxis is completely abolished, while the response to the control chemoattractant formyl-leu-met-phe is still maintained. The chemotaxis responses are not restored after pharmacological treatment of the pathology. The decreased chemotactic response could be linked to a decreased number of PBR receptors present on monocytes of generalized anxiety disorder patients.

Benzodiazepine receptors and diazepam binding inhibitor: a possible link between stress, anxiety and the immune system.

This review summarizes the evidence available on the involvement in stress of different classes of benzodiazepine receptors and their putative endogenous ligand, diazepam binding inhibitor (DBI), with particular reference to their role in modifications of the immune response. The presented data from in vitro, experimental, and clinical studies suggest that benzodiazepine receptors and DBI play a major role in regulating steroid production in both the adrenals and central nervous system, and may be involved in the activation of the hypothalamic-pituitary-adrenal axis in stress response.

Sensory impairment and quality of life in a community elderly population.

OBJECTIVE: To determine the association between quality of life measures and sensory impairment in aged individuals living at home. DESIGN: Survey SETTING: A community survey, carried out in the historical center of a town in Northern Italy. PATIENTS: 1191 non-institutionalized elders (age 70-75 years). MEASUREMENTS: Comprehensive QOL questionnaire, free-field voice testing, and Snellen eye chart. RESULTS: Single sensory impairments (either visual or auditory) were significantly and independently associated with increased risk for depression (odds ratio: 2.3, 95% confidence interval: 1.5-3.4; OR:1.8, CI:1.1-2.7, respectively) and decreased self-sufficiency in daily living activities (OR:1.7, CI:1.1-2.6; OR:2.1, CI:1.4-3.2, respectively). Visual dysfunction, but not hearing dysfunction, was independently associated with lower social relationships (OR:2.0, CI:1.3-3.1). CONCLUSION: The quality of life of community-dwelling elderly people is significantly linked to sensory impairment, which can be detected through simple physical examination. Mood level and social relationships are particularly affected by visual impairment, whereas self-sufficiency in daily living is more strongly related to hearing impairment.