The case of a 55-year-old female with oxalate-induced lethal encephalitis following infusions of sugar surrogates is reported. Renal failure and subsequent central coma developed following the use of xylitol, fructose and sorbitol above the recommended dosages. The patient died due to raised intracranial pressure. Cerebral damage was caused by encephalitis due to calcium oxalate crystals. Oxalosis induced by sugar surrogates may be explained either by dose-dependent toxic effects or genetically fixed intolerance.

To date, only few preclinical protocols on liposomal suicide gene transfer in tumors have been published, none of which directly compared viral to liposomal vectors in terms of immunoreactivity and efficacy. We thus studied the neuropathological alterations in 80 rats being treated for glioblastoma using liposomal and, for comparison, adenoviral and retroviral suicide gene transfer approaches to identify vector-associated efficacy and toxicity for further clinical studies. 62 rats served as controls. F98 tumors were established in Fisher rats and transfected in vivo with the thymidine kinase gene of herpes simplex virus (HSVtk) by a single intratumoral application and an implanted intratumoral continuous delivery system. Three days later ganciclovir was given intraperitoneally for 14 days. The animals were sacrificed 17 days post completed gene transfer. Brains were examined histologically and immunohistochemically using markers for immunocompetent cells. Ten animals showed complete tumor regression; they all belonged to the liposomal and adenoviral groups. In 6 of 10 experimental groups considerable numbers of lymphocytes along the margins of the regression cavities could be observed. Control animals of the liposomal and adenoviral groups showed only little lymphocytic infiltration, underlining the minimal immunogenicity of these carriers. In contrast, the retroviral control group featured a high lymphocyte infiltration. In summary, this study indicates that, in terms of both efficacy and immunoreaction, liposomes are as appropriate as adenoviruses in the treatment of rat glial tumors using suicide gene transfer strategies.

Experimental studies in extreme hypoxic conditions affecting the brain have been performed mainly in acute but not chronic models. Twenty rats were housed and exposed to decreasing concentrations of oxygen (from 21% to 7% over 130 days) and ten normal rats were used as control. Paraffin slices from representative sections containing cerebral cortex, cerebellum, striatum, hippocampus, thalamus and hypothalamus were incubated with antisera against nitric oxide synthase. Cortex and striatum showed small randomly distributed positive neurons with bipolar features, in greater numbers in the hypoxic group (p < 0.02). The granular layer of the cerebellum showed a strongly positive rim around some cell nuclei. Purkinje cells were immunopositive in hypoxic rats. Hipoccampal, thalamic and hypothalamic nuclei showed no quantitative differences in the number of positive neurons. The increased number of blood vessels and their dilation observed in some brain regions in hypoxic rats, mainly in ventral striatum, lead us to hypothesise that NOS may be over-expressed and act at these sites as vasomodulator and/or mediator of secondary cell injury affecting selective neuronal populations. We conclude that prolonged periods of adaptation to deep hypoxia reduces the effect of hypoxia on the upregulation of NOS in the brain tissue.

The whole-cell patch clamp technique was used to characterize voltage- and neurotransmitter-activated currents in the medulloblastoma cell line MHH-MED-3 and cells from tissue slices and primary cultures of two medulloblastoma biopsies. These preparations revealed similar electrophysiological properties. All tested cells displayed 4-aminopyridine-sensitive delayed rectifying K+ currents, γ-aminobutyric acidA receptor-mediated Cl− currents and most of them inward rectifier K+ currents. Transient inward currents were mainly carried by low-voltage activated T-type Ca2+ channels in MHH-MED-3 cells, and tetrodotoxin-sensitive Na+ channels in cells from the primary culture. From these characteristics we conclude that medulloblastoma cells share physiological features with developing cerebellar granule cells at an immature stage.

Dotarizine, a novel antimigraine prophylactic drug, is chemically related to Diphenylbutylpiperazines, which are known to have Ca(2+)-antagonistic, alpha-adrenolytic and antihistaminic properties. Additionally, Dotarizine exhibits strong 5-HT2 receptor-specific antiserotoninergic properties. The vasostabilizing effect of Dotarizine on cerebrovascular reactivity during different ventilation conditions was demonstrated in various in vitro and in vivo studies. In the presented study, the effect of chronic oral administration of the drug on vascular reactions of different areas of cerebral vessels following hyperventilation was investigated. The experiments were carried out on two groups of experimental animals (rabbits). In the first group (6) 25 mg/kg of Dotarizine dissolved in 0.25% agar was administered orally for 5 days twice daily. The control group of animals (6) was fed with agar of the same concentration according to the same time schedule. During the experiment, 15 min hyperventilation was performed and blood flow velocity (BFV) in the middle cerebral artery (MCA) and the basilar artery (BA) was recorded using Transcranial Doppler apparatus (TCD) before and after hyperventilation state. The obtained results revealed a strong antivasoconstrictive effect of Dotarizine on cerebral vessels reactivity during hyperventilation. In the control experimental group, the 15 min hyperventilation caused a decrease in the mean BFV in MCA and BA by 36 and 14%, respectively, and in the drug-treated group under the same ventilation conditions the decrease of the mean BFV in BA was only 6% and even a slight increase (8% as compared with control values) of BFV in MCA was observed. Comparison of the pulsatility index (PI) values demonstrated a significant decrease of vascular resistance in MCA in the Dotarizine-treated group of animals (P<0.1). From the obtained results it can be concluded that chronic oral administration of a novel compound (Dotarizine) diminishes the vasoconstrictive effect of hyperventilation on cerebral vessels in rabbits. The influence of this drug demonstrates regional differences in the cerebrovascular reactivity and it appears to change the vascular resistance in the small arteries of the cerebrovascular system. Thus, it can be recommended as a good prophylactic antimigraine compound due its vasostabilizing properties.

In the study presented the effect of Dotarizine on blood flow velocity in cerebral arteries – in middle cerebral artery (MCA), and basilar artery (BA)- was investigated and compared utilising transcranial Doppler sonography during normoventilation, 15 min hyperventilation with subsequent 3 min anoxia in anaesthetized rabbits. In the Dotarizine treated group (12 rabbits) 25 mg/kg of Dotarizine dissolved in 0,25% agar was admistered orally for five days twice daily. In the control group (9 rabbits) animals were fed with agar of the same concentration. The results revealed that decrease of flow velocity caused by hyperventilation and increase during anoxia were less pronounced in the Dotarizine treated group than in control group of animals. A difference between changes of flow velocity in MCA and BA during anoxia was found and the different reactivity of both vessels was established.

The vascular endothelial growth factor (VEGF) has been shown to be upregulated in acute hypoxia. Although an increase in blood vessel number has been described in severe chronic brain hypoxia, it is unclear whether VEGF is upregulated in this condition. We therefore investigated male inbred Wistar rats, which were exposed for 9 to 13 weeks to decreasing amounts of oxygen, down to 7% O2 (15%: 15 days; 12%, 10%, respectively; 8%: 1 day, 3 weeks, respectively; 7%: 4 weeks). The expression of VEGF was studied by Northern analysis and in situ hybridization in frozen sections of cerebral cortex, hippocampus and cerebellum in six chronic hypoxic and two control rats. We found a marked upregulation of VEGF mRNA in all brain regions investigated, being strongest in cerebral cortex and cerebellum. Our results suggest a potential role of VEGF for vascular growth and vascular permeability observed in chronic cerebral hypoxia.

Dotarizine--the novel piperazine derivative--belongs to wide spectrum Ca2+ channel antagonists. It was reported to have strong vasodilatatory and antiserotoninergic activities. Comparing with other Ca2+ channel blockers Dotarizine was found to have lower oral toxicity. In the present study the influence of the oral administration of the novel compound on the blood flow velocity changes in different cerebral arteries--in basilar artery (BA) and middle cerebral artery (MCA)--was investigated under hypoxic conditions. The ultrastructural morphological changes of intracerebral vessels endothelium in treated and untreated anoxic animal groups were also demonstrated. The experiments were carried out on rabbits. In the experimental group 25 mg/kg of Dotarizine dissolved in 0.25% agar was administered orally three times at the 10 hours' intervals. The sham group of animals was fed with agar of the same concentration. During anoxic conditions strong vasodilatory effects were observed in both investigated vessels of drug-treated animals. In the experimental group marked ultrastructural differences in parenchymal vessel endotheliumin comparison to sham group were revealed. Thus, the oral administration of Dotarizine might have effect on the various parts of the cerebrovascular system and can play significant role in improvement of various cerebrovascular disorders.

We studied the electrophysiological properties of cells from human glioblastomas obtained after surgery. The membrane currents were compared in cells of acute tissue slices and primary cultures using the whole cell mode of the patch-clamp technique. Very strikingly, in about a third of the tumor cells in situ and in vitro, depolarizing voltage steps elicited large, tetrodotoxin-sensitive inward currents with a threshold of about -30 mV, indicating the presence of voltage-gated sodium channels. In addition, three types of potassium currents, a delayed rectifying, an A-type, and an inward rectifying, were observed. Such a set of voltage-gated channels is characteristic for neurons. Indeed, in these glioblastoma cells, depolarizing current pulses in the current clamp mode were able to generate action potentials with properties similar to those observed in neurons. We interpret this finding as the ability of glioblastoma cells to acquire neuronlike properties but retain some glial features, since they still express markers typical for astrocytes and their precursors. The role of sodium channels in glioblastoma cells is unclear at this moment and needs further investigation. Our findings, however, imply that the tumor tissue can be intrinsically excitable and that neoplastic glial cells themselves may be an etiologic factor for epileptic seizures.

The involvement of three potent neurochemical mediators of the edema formation such as serotonin, prostaglandins and opioids in the pathophysiology of hyperthermic brain injury was examined in a rat model using a pharmacological approach. Hyperthermic brain injury was induced in conscious young rats by exposing them to heat stress at 38°C for 4 h. In these rats the blood-brain barrier (BBB) permeability, brain edema, cerebral blood flow (CBF), heat shock protein 72 kD (HSP) response and cell changes were examined. Pretreatment with ketanserin (a serotonin-2 receptor antagonist), indomethacin (prostaglandin synthesis inhibitor) and naloxone (opioid receptor antagonist) in separate groups of rats reduced hyperthermia and HSP response following heat stress and significantly attenuated changes in the BBB permeability, brain edema, CBF and cell reaction. These results suggest that the pathophysiology of hyperthermic brain injury is a complex mechanisms and several neurochemicals are involved in the brain pathology caused by heat stress.

Alterations of the p53 protein, which is a 53 kD phosphoprotein and gene product of the p53 gene, has been found to play a major role in the genesis of a variety of human malignancies including tumors of the central nervous system. We investigated 50 tumor specimens from primary central nervous system neoplasms. Tissue samples were screened for mutations by the single-strand conformation polymorphism method and detected mutations were sequenced. All tissue specimens were stained immunohistochemically for p53 protein, which when altered accumulates in the nucleus due to prolonged half-life. Mutations were found in six cases, including one pilocytic astrocytoma World Health Organization (WHO) grade I, two astrocytomas WHO grade II, two anaplastic astrocytomas WHO grade III, and one primitive neuroectodermal tumor (PNET). In terms of relative frequency mutations were found mostly in the group of anaplastic astrocytomas WHO grade III. Interestingly, no mutations were found in the group of investigated glioblastomas. P53 immunopositivity did not correlated with the mutations found, whereas the staining index was significantly higher in the cases with detected mutations than in those without. When p53 alterations is seen as an indicator for different pathogenic pathways in glioma formation, this study gives evidence for a difference between anaplastic astrocytoma and glioblastoma. However, since there was a great overlap in p53 immunopositivity and p53 mutation in tumors of different WHO grades and entities, it seems that p53 will not act as a marker molecule neither for tumor entities nor for tumor malignancy.

Dotarizine and Flunarizine are piperazine derivatives considered to be effective compounds for the treatment of various cerebrovascular disorders. In the present study the influence of these two drugs on changes in cerebral vessel diameter and blood flow velocity were measured and compared utilising transcranial Doppler sonography during hyperventilation in anaesthetized cats. Drugs were administered in 15 min intravenous infusions at a dose of 0.05 mg/kg/min. This investigation revealed that the 15 min intravenous administration of both compounds abolished the cerebral vasoconstrictor effects of hyperventilation and due to vasodilator effects they increased blood flow velocity to initial values. No statistically significant differences were found between the vasodilator effects of Dotarizine and Flunarizine. Results obtained suggest that Dotarizine, a novel piperazine derivative, has similar vasodilator and Ca2+ channel blocking effects on cerebrovascular reactivity compared to the widely clinically applied Flunarizine.

Recent molecular biological studies have shown evidence for a distinct pathogenesis of pilocytic astrocytomas based on alterations other than mutations of the tumor suppressor gene p53. To prove these data, the authors screened a series of 42 astrocytic human brain tumors with a relatively high proportion (16.6%) of the pilocytic variant for the presence of p53 mutations, using the polymerase chain reaction (PCR) and single-strand conformation polymorphism (SSCP) analysis, followed by DNA sequencing. Mutations were found in one of seven (14.3%) pilocytic astrocytomas, in one of 18 (5.6%) low grade astrocytomas, and in one of four (25%) anaplastic astrocytomas, but in none of 13 glioblastomas. Sites of missense mutations were in exon 8 (codons 281 and 282), and exon 5 (codon 151). Silent mutation was found in exon 9 (codon 324), which was related to pilocytic astrocytoma. This is, to the authors' knowledge, the first report that shows a p53 mutation in pilocytic astrocytomas. However, the p53 mutation was only found in one of seven tumors of this entity and was a silent mutation, which does not lead to change of amino acids. Thus, the significance of this alteration for the development of this special tumor type seems to be low. Nevertheless, it may be a sign of genetic instability and is thus suggested to be of certain pathogenetic relevance. The p53 findings concerning the other tumors are in accordance with the view of p53 gene mutations to be early events in astrocytoma formation.

One of the most common symptoms of patients with oligodendrogliomas is the high frequency of epileptic seizures. We thus studied the physiological properties of cells in six human oligodendrogliomas and two oligoastrocytomas obtained from surgical material. The majority of tumor cells in living brain slices can generate action potentials as recorded with the patch-clamp technique indicating that this tissue is dominated by electrically excitable cells. In cultures from the same material, the action potential generating cells prevail within the first days and are subsequently replaced by electrically inexcitable cells.From histopathological and immunohistochemical data, the histogenesis of human oligodendroglial tumor is still uncertain. Our physiological study has not settled the debate on the origin of these tumors but revealed important findings with regard to this question. Since action potential generating glial cells have not been described in situ so far their occurrence in oligodendroglial tumors implies that oligodendroglial tumor cells may belong to the neuronal cell lineage.

BACKGROUND AND PURPOSE We investigated the distribution and frequency of microthromboemboli (MTE) in acute infarcts in humans and determined whether MTE in the contralateral circulation resulted in histological changes. METHODS Forty patients dying within the first month after unilateral infarct were investigated. Infarct etiology was determined mainly on the pathological findings. Whole brain sections from the region of maximal necrosis were stained for fibrin. Fibrin-containing MTE were transferred to a schematic drawing and counted. Sections from 20 patients without infarcts served as controls. RESULTS Infarct sections had significantly more MTE than controls. Infarcts of thrombotic (n=6) and thromboembolic (n=21) origin had more MTE than infarcts of embolic origin (n=13). Thromboembolic infarcts had the highest number of MTE within the region assumed to be the ischemic penumbra, other arterial territories, and the contralateral hemisphere. Patients with large infarcts and those with short clinical courses had a higher number of MTE. Sixteen patients had recent micronecroses in the contralateral hemisphere. CONCLUSIONS There seems to be a pattern of MTE in acute infarcts that is dependent on cause, size, and clinical duration. Our findings of contralateral micronecroses emphasize that acute infarcts may result in more widespread cerebral injury than clinically expected. Given the many variables influencing stroke and death in humans, the results have to be interpreted with caution.