Efficacy of flupirtine on cognitive function in patients with CJD: A double-blind study.

BACKGROUND: In cell culture experiments, flupirtine maleate (FLU), a triaminopyridine compound, was able to protect neuronal cells from apoptotic cell death induced by prion protein fragments and beta-amyloid peptides. As FLU is a clinically safe drug, the authors started a double-blind placebo-controlled study in patients with Creutzfeldt-Jakob disease (CJD). METHODS: Twenty-eight patients with CJD were randomized to an oral treatment with either FLU (n = 13) or matching placebo (PLA; n = 15). For inclusion and continuing the study, the patients had to achieve at least 50% in two of the subscales of the dementia tests employed. A battery of standardized questionnaires was employed to monitor the progression of the disease. The main outcome variable was the cognitive part of the Alzheimer's Disease Assessment Scale (ADAS-Cog); the difference between baseline and the best score under treatment was defined as the primary efficacy variable for hypothesis testing. RESULTS: CJD types were homogeneously distributed among the treatment groups. Patients treated with FLU showed significantly less deterioration in the dementia tests than patients treated with PLA. The mean change in ADAS-Cog (baseline to best) was +8.4 (+/-15.3) in the FLU group and +20.6 (+/-15.1) in the PLA group (p = 0.02, one-sided t-test). CONCLUSIONS: FLU has beneficial effects on cognitive function in patients with CJD. These positive results also may suggest a treatment potential of FLU in other neurodegenerative disorders. However, further studies are necessary.

[Polyneuropathy as a sole syndrome in malignant thymoma]. / Polyneuropathie als einziges paraneoplastisches Syndrom bei malignem Thymom.

Up to 40% of patients with malignant thymoma suffer from paraneoplastic symptoms (90% myasthenia, 10% other symptoms). A 55-year-old patient developed ascending symmetrical sensorimotor tetraparesis. A malignant thymoma without metastases was diagnosed 6 months later. Despite thymectomy followed by radiation and high-dose corticosteroid therapy, the polyneuropathy progressed. Six months after onset, the patient was bound to a wheelchair. Immunosuppressive therapy with cyclophosphamide was initiated, leading to marked remission. After ten cycles, the patient was able to walk independently with walking aids. After the sixth and tenth cycle, respectively, attempts to discontinue immunosuppression led to relapse. In several diagnostic workups, however, there was no tumour relapse. After 13 cycles, cyclophosphamide was replaced by immunoglobulins (0.4 g/kg per day i.v. for 5 days/month) due to progressive renal failure. The patient died just before the second course of this treatment. In conclusion, in the differential diagnosis of rapidly progressive polyneuropathy, a malignant thymoma should be considered, even in the absence of myasthenia. Immunosuppression with cyclophosphamide resulted in amelioration of symptoms in this patient.

Unaltered apoptotic behaviour of mononuclear cells from patients with sporadic Creutzfeldt-Jakob disease.

Creutzfeldt-Jakob disease (CJD) belongs to the group of transmissible spongiform encephalopathies. It is suspected that a pathologically altered form of the prion protein (PrPSc) is the decisive trigger of the disease. Data from animal experiments suggest an involvement of the lymphatic system in the intracorporal transport of PrPSc. However, it has not so far been possible to detect PrPSc on mononuclear cells (MNCs) either in the sporadic form of CJD or in the new variant of CJD (vCJD). In order to determine a possible alteration of MNCs in CJD, we investigated the natural and induced apoptotic behaviour of these cells. MNCs from 19 patients with sporadic CJD and from 20 patients with other neurological disorders were used. The cells were analysed by fluorescence cytometry with and without apoptosis induction by xanthine oxidase and hypoxanthine. The apoptosis rate was quantified using the stain 7-amino-actinomycin D (7-AAD). In the morphological investigation of the cells before apoptosis induction, there were no significant differences between the groups with regard to cell size and granularity of the MNCs. After apoptosis induction, the typical significant decrease in cell size and increase in granularity of the cells occurred in both groups. Significant differences between the patient populations were not found. For the first time, our investigation has demonstrated that a functional impairment of MNCs with regard to their apoptotic behaviour does not occur in sporadic CJD. It remains open to question whether this mechanism plays an important role in forms of transmissible encephalopathy other than sporadic CJD, especially after oral transmission.

Decreased beta-amyloid1-42 in cerebrospinal fluid of patients with Creutzfeldt-Jakob disease.

OBJECTIVES: Decreased levels of Abeta1-42 are found in CSF of patients with AD. Because early stages of Creutzfeldt-Jakob disease (CJD) and AD share several clinical features, we investigated Abeta1-42 levels in CSF of these groups, inferring that this might give additional help in differentiating patients with CJD from AD patients. METHODS: We investigated 27 patients with CJD, 14 patients with AD, 19 patients with other dementias, and 20 nondemented controls (NDC) for Abeta1-42 in CSF. Twenty-four of the 27 CJD patients were neuropathologically verified. All the neuropathologically verified patients presented with a type 1 prion protein pattern. CJD patients were all homozygous for methionine at codon 129. Except in five CJD patients, no beta-amyloid plaques were seen. Additionally, APOE status was determined in patients with CJD. RESULTS: Levels of Abeta1-42 in CSF were decreased in patients with AD as well as in CJD. Levels of Abeta1-42 in CSF of patients with CJD and AD were significantly different from the other dementia and NDC groups. There was no substantial difference between the CJD and AD groups (p = 0.66). Decreased levels of Abeta1-42 did not correlate with the APOE epsilon4 load in patients with CJD. CONCLUSION: Low levels of Abeta1-42 in CSF do not exclude a diagnosis of CJD. Decreased levels of Abeta1-42 in CSF can occur without beta-amyloid plaque formation in the brain. However, the underlying mechanism of this phenomenon must be elucidated.

Imidazolines and the pancreatic B-cell. Actions and binding sites.

Stimulation of insulin secretion by imidazoline compounds displays variable characteristics. Phentolamine (10-100 microM) increased secretion of perifused mouse islets at nonstimulatory glucose concentrations (5 mM) and even in the absence of glucose. Idazoxan (20-100 microM) elicited a moderate increase in insulin secretion, which required the presence of a stimulatory glucose concentration (10 mM). Phentolamine is therefore a stimulator of secretion in its own right, whereas idazoxan may be termed an enhancer of secretion. Both compounds inhibited the activity of ATP-dependent K+ channels in inside-out patches from B-cells; however, idazoxan achieved only an incomplete block. Both compounds depolarized the B-cell plasma membrane to an extent that permitted the opening of voltage-dependent Ca2+ channels (-40 to -30 mV). An increase in cytoplasmic Ca2+ concentration was induced by phentolamine and much less so by idazoxan. Activation of protein kinase C, a possible mechanism to amplify Ca(2+)-induced secretion, could not be verified for phentolamine. It thus appears that stimulation of insulin secretion by phentolamine is due to its blocking effect on KATP channels, which may be the correlate of non-adrenergic imidazoline binding sites which were characterized in insulin-secreting HIT cells. Whether incomplete closure of KATP channels by idazoxan or additional effects are responsible for the requirement of high glucose to stimulate secretion remains to be clarified.

Imidazoline/guanidinium binding sites and their relation to inhibition of K(ATP) channels in pancreatic B-cells.

To elucidate the beta-cytotropic effect of imidazoline compounds their inhibitory effect on ATP-dependent K+ channels (K(ATP) channels) in pancreatic B-cells was compared with their binding to membranes from insulin-secreting HIT T15 cells. K(ATP) channels in inside-out patches from B-cells were closed with the following rank order of efficacy at 10 microM: guanabenz > phentolamine = alinidine > clonidine > idazoxan > rilmenidine = amiloride. The last four compounds achieved an incomplete inhibition only. In contrast to sulfonylureas, the inhibitory action of imidazolines was not enhanced by ADP. With intact cells the site which mediates inhibition is less easily accessible for protonated compounds, suggesting a location at the inner face of the plasma membrane. Competition binding experiments were performed by masking alpha-adrenoceptors and using [3H]clonidine as ligand. Homologous displacement of [3H]clonidine revealed two distinct binding sites in HIT cell membranes characterized by dissociation constants of 38 nM and 4,911 nM and maximal binding capacities of 118 fmol/mg protein and 18 pmol/mg protein. Generally, ligands for I2 imidazoline receptors were more potent than ligands for I1 imidazoline receptors to displace [3H]clonidine from the high affinity site, which does not fit into the current classification of imidazoline receptors. Binding to the second site had affinities in the micromolar range, similar to the concentrations necessary to inhibit K(ATP) channels in B-cells. However, alinidine and phentolamine inhibited K(ATP) channels already at concentrations at which they displaced [3H]clonidine only from the high affinity site, but not yet from the low affinity site. Since the proportion of the low and high affinity site varied in dependence of the competitor, the imidazoline binding sites in HIT cells may not be independent, but may rather represent two interacting or interconvertible sites both of which may be involved in K(ATP) channel closure.

Effects of imidazoline compounds on cytoplasmic Ca2+ concentration and ATP-sensitive K+ channels in pancreatic B-cells.

Phentolamine, an alpha-adrenoceptor-blocking agent with an imidazoline structure, induces an increase in the cytoplasmic Ca2+ concentration of pancreatic B-cells. This effect occurs at a concentration (32 microM) at which phentolamine is able to enhance glucose-induced insulin secretion. The increase in cytoplasmic Ca2+ concentration caused by phentolamine is additive to the one elicited by a maximally effective concentration of tolbutamide (100 microM). Imidazoline-binding sites in insulin-secreting HIT cells can also be occupied by the guanidinium compound guanabenz, which was found to be a potent and reversible blocker of ATP-dependent K(+)-channels in B-cells. In contrast to phentolamine, guanabenz blocks the ATP-dependent K(+)-channels only in the inside-out mode, but not in the cell-attached mode of the patch-clamp technique. In conclusion, imidazolines and structurally related compounds block ATP-dependent K(+)-channels by binding to the cytoplasmic face of the plasma membrane, and may have effects on other ion channels which contribute to the elevation of cytoplasmic Ca2+ concentration and, consequently, to insulin release.