The central nervous system effects, pharmacokinetics and safety of the NAALADase-inhibitor GPI 5693.

AIM: The aim was to assess the central nervous system (CNS) effects, pharmacokinetics and safety of GPI 5693, an inhibitor of a novel CNS-drug target, NAALADase which is being evaluated for the treatment of neuropathic pain. METHODS: This was a double-blind, placebo-controlled, exploratory study in healthy subjects receiving oral GPI 5693 single ascending doses of 100, 300, 750, 1125 mg with a placebo treatment randomly interspersed. An open-label, parallel extension examined the effects of food and sex on the pharmacokinetics of 750, 1125 and 1500 mg doses. Blood samples were collected for pharmacokinetic and biochemical/haematological safety analysis, vital signs, ECG and adverse event checks were performed regularly up to 48 h postdose. Postdose CNS effects were assessed using eye movements, adaptive tracking, electroencephalography (EEG), body sway and Visual Analogue Scales (VAS). RESULTS: CNS effects were mainly observed after the 1125 mg dose, showing a significant decrease of adaptive tracking performance, VAS alertness and VAS mood, and an increase of EEG occipital alpha and theta power. Gastro-intestinal (GI) adverse effects were frequent at higher doses. No clinically significant changes in vital signs or ECG were noted during any of the treatments. The therapeutically relevant concentration range (950-11 100 ng ml(-1)) as determined from animal experiments was already reached after the 300 mg dose. C(max) after the 300 mg and 750 mg dose was 2868 and 9266 ng ml(-1) with a t(1/2) of 2.54 and 4.78 h, respectively. Concomitant food intake (with the 750 mg and 1125 mg doses) reduced C(max) by approximately 66% and AUC by approximately 40%. With concomitant food intake, the dose-normalized C(max) also decreased significantly by -5.6 (CI: -2.6 to -8.7) ng ml(-1) mg(-1). The pharmacokinetic variability was largest after the 300 mg and 750 mg dose, resulting in a SD of approximately 50% of the C(max). CONCLUSION: NAALADase inhibition with GPI 5693 was safe and tolerable in healthy subjects. Plasma concentrations that were effective in the reversal of hyperalgesia in the chronic constrictive injury animal model of neuropathic pain were obtained at doses of 300, 750 and 1125 mg in the fasted state. Comcomitant food intake reduced C(max) and AUC. CNS effects and GI AEs increased in incidence over placebo only at the 1125 mg dose.

Topographical distribution of [125I]-glial cell line-derived neurotrophic factor in unlesioned and MPTP-lesioned rhesus monkey brain following a bolus intraventricular injection.

The present study determined the topographical distribution profile for [125I]-glial cell line-derived neurotrophic factor in unlesioned and MPTP-lesioned (unilateral intracarotid injection) rhesus monkeys following an intraventricular injection. Autoradiographic analysis showed that following a bolus intraventricular injection, there was widespread distribution of [125I]-glial cell line-derived neurotrophic factor throughout the ventricular system (walls of lateral, third, and fourth ventricles and aqueduct), with some accumulation at the lateral ventricle injection site, possibly associated with the ependymal cell layer. In both unlesioned and MPTP-lesioned monkeys, there was labelling of the cerebral cortex, substantia nigra/ventral tegmental area and sequestration of [125I]-glial cell line-derived neurotrophic factor adjacent to the hippocampal formation, globus pallidus, ventral to and in the substantia nigra. However, [125I]-glial cell line-derived neurotrophic factor did not appear to diffuse readily or accumulate in the caudate-putamen even though there was some penetration away from the ventricular walls. Throughout the brain, there was also substantial non-parenchymal labelling of [125I]-glial cell line-derived neurotrophic factor, possibly associated with extracellular matrix components, meninges and vasculature due to the heparin binding properties of glial cell line-derived neurotrophic factor. In addition to the extensive loss of tyrosine hydroxylase immunoreactivity within the substantia nigra, there was also decreased accumulation of [125I]-glial cell line-derived neurotrophic factor and reduced glial cell line-derived neurotrophic factor immunoreactivity ipsilateral to the lesion. Microscopic analysis showed that glial cell line-derived neurotrophic factor immunoreactivity was associated with upper cortical layers including a high density of immunoreactivity at the surface of the cortex (meningeal, pial layer, vasculature) and around the ventricular walls (with some cellular labelling and labelling of vasculature). Moderate staining was observed in nigral cells contralateral to the MPTP-lesion, whereas only minimal levels of that glial cell line-derived neurotrophic factor immunoreactivity were detected ipsilateral to the lesion. This study shows that intraventricularly injected glial cell line-derived neurotrophic factor accumulates not only around the ventricular walls, but also in specific brain regions in which sub-populations of cells are more readily accessible than others. The presence of cells labelled with [125I] and immunopositive for glial cell line-derived neurotrophic factor in the substantia nigra indicates that these cells are a target for the trophic factor following intraventricular administration. Thus, the behavioral improvement observed in MPTP-lesioned monkeys following an intraventricular injection of glial cell line-derived neurotrophic factor is likely the result of activation of nigral cells.

Basic fibroblast growth factor-2 and interleukin-1 beta regulate S100 beta expression in cultured astrocytes.

Basic fibroblast growth factor and interleukin-1 beta are known to regulate the expression of other trophic factors and to stimulate reactive gliosis in vivo. S100 beta is a glial-specific putative neurotrophic factor and has been considered a marker of the reactive status of astrocytes. Therefore, we tested the hypothesis that basic fibroblast growth factor-2 and interleukin-1 beta achieve their effects by altering S100 beta gene expression in cultured rat astrocytes using an RNase protection assay. Short-term treatment with basic fibroblast growth factor-2 produced a transient decrease in S100 beta messenger RNA which was followed by an increase after longer term treatment. In contrast, both short- and long-term treatment with interleukin-1 beta suppressed S100 beta messenger RNA. We measured levels of S100 beta nuclear primary transcript to assess whether alterations in transcriptional rate explain the changes in messenger RNA. Our results indicate that changes in transcription account for changes in steady state levels of messenger RNA since basic fibroblast growth factor-2-induced changes in S100 beta primary transcript temporally preceded changes in messenger RNA. We further measured intracellular S100 beta protein levels by enzyme-linked immunosorbent assay to determine whether changes in gene expression were translated into parallel changes in protein. Our results clearly demonstrate that basic fibroblast growth factor-2 and interleukin-1 beta influence the expression of the S100 beta gene, that this regulation appears to occur at the level of transcription, and that alterations in messenger RNA are sometimes, but not always, reflected in changes at the level of protein. These observations suggest that basic fibroblast growth factor-2 may amplify its trophic effects, in part, by influencing the expression of another trophic factor.

Glial cell line-derived neurotrophic factor attenuates the locomotor hypofunction and striatonigral neurochemical deficits induced by chronic systemic administration of the mitochondrial toxin 3-nitropropionic acid.

The present study investigated whether glial cell line-derived neurotrophic factor prevents the progressive striatal degeneration induced by chronic systemic administration of the mitochondrial toxin, 3-nitropropionic acid. In addition, the effects of delayed treatment with glial cell line-derived neurotrophic factor on toxin-induced behavioural and neurochemical deficits were determined. Locomotor activity in rats infused with 3-nitropropionic acid (15 mg/kg/day, for four weeks) via subcutaneous osmotic minipumps was considerably reduced compared to control rats. However, in rats given a single intracerebroventricular injection of 100 micrograms of glial cell line-derived neurotrophic factor, locomotor activity was significantly higher than in rats injected with the vehicle, an effect that was most pronounced at the onset of toxin infusion. Consistent with a protective or restorative effect in this model of striatal neurodegeneration, toxin-induced deficits in markers of neurotransmitter function were attenuated by glial cell line-derived neurotrophic factor. Thus, [3H]GABA uptake and [3H]tiagabine/GABA uptake sites in striatal target tissues (globus pallidus and substantia nigra), as well as [3H]choline uptake, choline acetyltransferase activity and dopamine receptor binding in the striatum were decreased by the toxin and restored to varying degrees by glial cell line-derived neurotrophic factor administration. As with locomotor abnormalities, effects on neurochemical deficits were most prominent when glial cell line-derived neurotrophic factor was given at the start of toxin infusion, but remained significantly higher than in the vehicle-injected rats when given up to two weeks after. Substance P, dynorphin A and [Met]enkephalin levels in the striatal target tissues also were reduced by 3-nitropropionic acid. The results show that glial cell line-derived neurotrophic factor protects striatal neurons from slow excitotoxic cell death resulting from energy deprivation, secondary to mitochondrial dysfunction. Moreover, they suggest that glial cell line-derived neurotrophic factor may be a viable therapeutic agent for slowly progressive central nervous system disorders, like Huntington's disease, that may be caused by secondary excitotoxicity resulting from abnormal energy utilization.

Glial cell line-derived neurotrophic factor attenuates the excitotoxin-induced behavioral and neurochemical deficits in a rodent model of Huntington's disease.

The present study determined the effects of intraventricularly administered glial cell line-derived neurotrophic factor on the behavioral and neurochemical sequelae of unilateral excitotoxic lesions of the striatum. Distinct asymmetrical rotational behavior in response to peripheral administration of amphetamine (5 mg/kg) was noted one and two weeks following injections of quinolinic acid (200 nmol) into two sites in the left striatum. In rats given a single intraventricular injection of glial cell line-derived neurotrophic factor (10-1000 micrograms) 30 min before the toxin, amphetamine-induced rotational behavior was significantly attenuated. Analysis of Nissl-stained coronal sections showed marked neuronal loss in the striatum ipsilateral to the quinolinic acid injections, which was at least partially prevented by glial cell line-derived neurotrophic factor D1 and D2 dopamine binding sites in the striatum, the majority of which are localized to subpopulations of GABAergic neurons, were decreased to a similar extent by quinolinic acid. Moreover, the reduction was attenuated by glial cell line-derived neurotrophic factor treatment to a similar degree, suggesting that the two subpopulations of GABAergic striatal output neurons are equally vulnerable to excitotoxic damage. Concomitant changes in neurotransmitter function as a result of the lesion were also observed: [3H]GABA uptake into striatal target tissues (globus pallidus and substantia nigra) was considerably reduced in the lesioned compared to the contralateral unlesioned tissues, as were [3H]choline and [3H]dopamine uptake into striatal synaptosomes. Similarly, striatal choline acetyltransferase activity was decreased by the lesion. Decrements in neuropeptide levels of similar magnitude were evident ipsilateral to the lesion; substance P, met-enkephalin and dynorphin A contents in the globus pallidus and substantia nigra were significantly reduced. Striatal somatostatin and neuropeptide Y levels were not altered. All of the neurochemical deficits induced by striatal quinolinic acid lesions were attenuated by intraventricular delivery of glial cell line-derived neurotrophic factor. Continuous intraventricular infusion of this trophic factor (10 micrograms/day) over a two-week period did not afford notable improvement compared to the single injection of 10 micrograms. In contrast, continuous infusion of brain-derived neurotrophic factor (10 micrograms/day) directly into the striatum did not affect any of the neurochemical parameters studied. However, neurotrophin-3 (10 micrograms/day) delivery into the striatum significantly increased [3H]GABA uptake, but only modestly affected [3H]choline uptake. The results indicate that glial cell line-derived neurotrophic factor counteracts neuronal damage induced by a striatal excitotoxic insult and support its potential use as a treatment for central nervous system disorders that may be a consequence of excitotoxic processes, such as Huntington's disease.

ret receptor tyrosine kinase immunoreactivity is altered in glial cell line-derived neurotrophic factor-responsive neurons following lesions of the nigrostriatal and septohippocampal pathways.

Glial cell line-derived neurotrophic factor was initially identified as a survival factor for developing midbrain dopamine neurons (for reviews, see Refs 17 and 19). Subsequent studies have demonstrated a more wide-spread role for glial cell line-derived neurotrophic factor in the developing and adult CNS. In the adult rat brain, for instance, prior administration of glial cell line-derived neurotrophic factor protects nigrostriatal dopamine neurons from 6-hydroxydopamine-induced damage. When given several weeks after 6-hydroxydopamine injection, glial cell line-derived neurotrophic factor also restores the function of these neurons. Glial cell line-derived neurotrophic factor attenuates excitotoxin-induced cell death in the striatum and hippocampal formation and protective effects of glial cell line-derived neurotrophic factor following axotomy have been reported for spinal motor neurons and basal forebrain cholinergic neurons. These findings suggest that glial cell line-derived neurotrophic factor may be a protective/restorative agent for a diverse population of neurons and imply that it may be a useful therapeutic tool for a variety of neurodegenerative diseases including Parkinson's, Huntington's and Alzheimer's diseases. The potential receptor mediating the pleiotropic effects of glial cell line-derived neurotrophic factor has been characterized only recently as a novel glycosyl-phosphatidylinositol-linked protein, GDNFR-alpha. Because GDNFR-alpha is a cell surface receptor, an additional protein(s) was thought to be involved in the glial cell line-derived neurotrophic factor signalling cascade. The identity of the likely candidate, ret, was inferred initially from indirect evidence. Not only were there remarkable similarities in the distribution of glial cell line-derived neurotrophic factor and the proto-oncogene ret in the developing rat and mouse brain, but also in the phenotype of glial cell line-derived neurotrophic factor knockout mice and mice with ret mutations. Mice with either mutation exhibited pronounced renal and enteric abnormalities, implicating the receptor tyrosine kinase protein product of the ret proto-oncogene as the glial cell line-derived neurotrophic factor signalling protein. More conclusive evidence showing that activation of GDNFR-alpha by glial cell line-derived neurotrophic factor induces phosphorylation of ret has confirmed ret as a signalling protein for glial cell line-derived neurotrophic factor. Preliminary results showing that 6-hydroxydopamine lesions of the substantia nigra markedly reduced ret messenger RNA expression, established its localization to presumably glial cell line-derived neurotrophic factor-responsive dopamine neurons in the nigrostriatal pathway. In contrast, it is not clear whether other glial cell line-derived neurotrophic factor-responsive neurons in the CNS, such as the basal forebrain cholinergic neurons and striatal neurons, also express ret, nor is it evident whether levels of the protein are regulated by disruption of the respective pathways. The present study shows that dense networks of ret immunoreactivity are distributed throughout the nigrostriatal pathway, with lower densities of staining in other brain regions, including the septohippocampal pathway. Following extensive unilateral 6-hydroxydopamine lesions of the medial forebrain bundle, ret immunoreactivity in the substantia nigra and striatum was reduced significantly, to a similar extent as tyrosine hydroxylase immunoreactivity. In contrast, excitotoxic lesions of the striatum, achieved by intrastriatal quinolinic acid injections, resulted in increased ret staining in this brain region. In addition, marked decrements in septal ret immunoreactivity were consequent to complete transections of the fimbria-fornix.

Transactivation of proenkephalin gene by HTLV-1 tax1 protein in glial cells: involvement of Fos/Jun complex at an AP-1 element in the proenkephalin gene promoter.

The human T-cell lymphotropic virus type 1 (HTLV-1), an etiologic agent for adult T-cell leukemia, is strongly associated with tropical spastic paraparesis, a chronic neurological disease. The HTLV-1 genome encodes a protein, tax1, an autoregulator of enhanced viral RNA transcription, that also transactivates/represses certain cellular gene promoters. Enkephalins are opioid peptides that function as neurotransmitters and neuroimmunomodulators. We earlier reported that the proenkephalin gene is transactivated by tax1 protein in glial cells. The nucleotide sequence upstream of -190 base pairs in the proenkephalin gene promoter is necessary for maximal transactivation by tax1 while the sequence downstream of -190 bp confers modest activation by tax1. We investigated the cellular transcription factors in tax1 expressing glial cells that associate with the proenkephalin promoter and herein demonstrate the enhanced interaction and involvement of c-Fos/c-Jun proteins in the complexes formed at the AP-1 site. The HTLV-1 tax1 expressing stable glial cell lines produced functional tax1 protein that increased the expression of endogenous proenkephalin gene. The comparative electrophoretic mobility shift and 'supershift' analysis using specific antibodies indicated the enhanced presence of c-Fos and c-Jun proteins in the DNA: protein complex formed at the AP-1 site. The c-Fos protein expression significantly increased in the tax1 expressing glial cells. The tax1 induced c-Fos protein levels and the concurrently increased association of c-Fos/c-Jun transcription factors at the AP-1 site imply a strong functional significance in the activation of proenkephalin gene expression in tax1 expressing glial cells.

Adenoviral vector-mediated GDNF gene therapy in a rodent lesion model of late stage Parkinson's disease.

A recombinant adenoviral vector encoding the human glial cell line-derived neurotrophic factor (GDNF) gene (Ad-GDNF) was used to express the neurotrophic factor GDNF in the unilaterally 6-hydroxydopamine (6-OHDA) denervated substantia nigra (SN) of adult rats ten weeks following the 6-OHDA injection. 6-OHDA lesions significantly increased apomorphine-induced (contralateral) rotations and reduced striatal and nigral dopamine (DA) levels by 99% and 70%, respectively. Ad-GDNF significantly (P < 0.01) decreased (by 30-40%) apomorphine-induced rotations in lesioned rats for up to two weeks following a single injection. Locomotor activity, assessed 7 days following the Ad-GDNF injection, was also significantly (P < 0.05) increased (by 300-400%). Two weeks after the Ad-GDNF injection, locomotor activity was still significantly increased compared to the Ad-beta-gal-injected 6-OHDA lesioned (control) group. Additionally, in Ad-GDNF-injected rats, there was a significant decrease (10-13%) in weight gain which persisted for approximately two weeks following the injection. Consistent with the behavioral changes, levels of DA and the metabolite dihydroxyphenylacetic acid (DOPAC) were elevated (by 98% and 65%, respectively) in the SN, but not the striatum of Ad-GDNF-injected rats. Overall, a single Ad-GDNF injection had significant effects for 2-3 weeks following administration. These results suggest that virally delivered GDNF promotes the recovery of nigral dopaminergic tone (i.e.: increased DA and DOPAC levels) and improves behavioral performance (i.e.: decreased rotations, increased locomotion) in rodents with extensive nigrostriatal dopaminergic denervation. Moreover, our results suggest that viral delivery of trophic factors may be used eventually to treat neurodegenerative diseases such as Parkinson's disease.

1H, 13C and 15N NMR assignments and solution secondary structure of rat Apo-S100 beta.

The 1H, 13C and 15N NMR assignments of the backbone and side-chain resonances of rat S100 beta were made at pH 6.5 and 37 degrees C using heteronuclear multidimensional NMR spectroscopy. Analysis of the NOE correlations, together with amide exchange rate and 1H alpha, 13C alpha and 13C beta chemical shift data, provided extensive secondary structural information. Thus, the secondary structure of S100 beta was determined to comprise four helices (Leu3-Ser18, helix I; Lys29-Leu40, helix II; Gln50-Glu62, helix III; and Phe70-Ala83, helix IV), four loops (Gly19-His25, loop I; Ser41-Glu49, loop II; Asp63-Gly66, loop III; and Cys84-Glu91, loop IV) and two beta-strands (Lys26-Lys28, beta-strand I and Glu67-Asp69, beta-strand II). The beta-strands were found to align in an antiparallel manner to form a very small beta-sheet. This secondary structure is consistent with predictions that S100 beta contains two 'helix-loop-helix' Ca(2+)-binding motifs known as EF-hands. The alignment of the beta-sheet, which brings the two EF-hand domains of S100 beta into close proximity, is similar to that of several other Ca(2+)-ion-binding proteins.

Molecular cloning of TOPAP: a topographically graded protein in the developing chick visual system.

Topographically graded molecules representing position-specific differences among otherwise similar cells are thought to play a role in the patterning of the developing nervous system. In the embryonic chick visual system, a 40 kDa protein, TOPAP, is expressed in a posterior > anterior gradient in the retina and in an inverted anterior > posterior gradient in the optic tectum, the major retinal projection area. Here we report the isolation and nucleotide sequencing of a complementary DNA clone encoding the chick TOPAP protein and demonstrate that the mRNA encoding this coiled-coil integral membrane protein is topographically graded within the retina and is present in a variety of chick tissues.

Astrocytosis and axonal proliferation in the hippocampus of S100b transgenic mice.

S100 beta is a calcium-binding protein that is expressed at high levels in brain primarily by astrocytes. Addition of the disulfide-bonded dimeric form of S100 beta to primary neuronal and glial cultures and established cell lines induces axonal extension and alterations in astrocyte proliferation and phenotype, but evidence that S100 beta exerts the same effects in vivo has not been presented. An 8.9-kb murine S100b genomic clone was used to produce two lines of transgenic mice in which S100 beta RNA is increased in a dose-related manner to 2-fold and 7-fold above normal. These lines show concomitant increased S100 beta protein throughout the brain. Expression in both lines is cell type- and tissue-appropriate, and expression levels are correlated with the transgene copy number, demonstrating that sequences necessary for normal regulation of the gene are included within the cloned segment. In the hippocampus of adult transgenic mice, Western blotting detects elevated levels of glial fibrillary acidic protein and several markers of axonal sprouting, including neurofilament L, phosphorylated epitopes of neurofilament H and M, and beta-tubulin. Immunocytochemistry demonstrates alterations in astrocyte morphology and axonal sprouting, especially in the dentate gyrus. Thus, both astrocytosis and neurite proliferation occur in transgenic mice expressing elevated levels of S100 beta. These transgenic mice provide a useful model for studies of the role of S100 beta in glial-neuronal interactions in normal development and function of the brain and for analyzing the significance of elevated levels of S100 beta in Down syndrome and Alzheimer disease.

Organization, sequence, and expression of the murine S100 beta gene. Transcriptional regulation by cell type-specific cis-acting regulatory elements.

The organization, sequence, and transcriptional regulation of expression of the murine S100 beta gene are reported. The gene is approximately 9 kilobase pairs in length and is composed of three exons and two introns. The deduced murine S100 beta protein sequence differs from the human S100 beta protein by only 1 amino acid. The murine S100 beta gene contains a TATA box (AATAA) and a reverse CCAAT box (ATTGG) located at 30 nucleotides and 92 nucleotides upstream of the cap site, respectively. A 149-base pair DNA fragment (-157/-9) spanning the TATA box and the reverse CCAAT box functions as a promoter. The murine S100 beta promoter drives a 4-fold higher level of transcription in glial (C6) than in non-glial (3T3) cells, suggesting the existence of a potential cell type-specific regulatory element within the promoter region. The 5'-flanking region suppresses transcription from the homologous S100 beta as well as the heterologous SV40 promoters in an orientation-independent fashion. However, the 5'-flanking region exhibits cell type specificity when suppressing the S100 beta promoter-dependent transcription, indicating its involvement in the cell type-specific expression of S100 beta gene. In order to map cell type-specific regulatory elements, transcription analyses of various deletions of the 5'-region were carried out in C6 and 3T3 cells. Two cell type-specific negative regulatory elements, one active in non-glial cells and another active in glial cells, were mapped to the regions -1552/-1234 and -1234/-551, respectively. A strong negative regulatory element and a relatively weak negative element were located in the regions -551/-157 and -1669/-1552, respectively. The murine S100 beta gene is under complex transcriptional regulation involving tonic negative control exerted by combination of multiple cis-acting regulatory elements including cell type-specific elements.

Anticholinergic delirium caused by topical homatropine ophthalmologic solution: confirmation by anticholinergic radioreceptor assay in two cases.

The authors report two patients with prolonged metabolic delirium presumably initiated by systemic absorption of homatropine from a topical ophthalmologic solution. Anticholinergic toxicity was confirmed by muscarinic radioreceptor assay in both cases and by quantitative EEG in one case.

Molecular cloning and regional distribution of rat brain cyclophilin.

Cyclosporine A (CsA) is a potent immunosuppressive drug that has widespread clinical uses in organ transplantation and the treatment of autoimmune disorders. However, the drug's clinical applications are on an empiric basis with a poor understanding of the basic mechanism(s) of action. CsA may exert some of its effects by binding to a cellular receptor protein--the cyclosporine receptor (also called cyclophilin). Cyclophilin (CyP) is an ubiquitous, soluble, cytoplasmic 17 kDa protein which has recently been shown to be a peptide-prolyl isomerase. CsA specifically binds to this protein and inhibits its isomerase activity. A rat cyclophilin cDNA clone was isolated from a rat brain lambda gt11 cDNA library. Northern blot analysis shows a single 1 kb messenger RNA in rat brain. In order to determine the regional distribution of the Cyp mRNA in situ hybridization was performed. The Cyp mRNA appeared to be expressed throughout the brain but there were particularly high levels in the cerebral cortex and hippocampus compared to the relatively low levels in white matter areas and tracts. At the cellular level, the Cyp mRNA is expressed at much higher levels in neurons than in glia. The high levels of Cyp in cortical (neuronal) areas may, in part, explain the global encephalopathic symptoms clinically observed in CsA neurotoxicity.

Transcriptional regulation of glutamine synthetase gene expression by dexamethasone in L6 muscle cells.

Dexamethasone increases glutamine synthetase activity and mRNA abundance in L6 muscle cells in culture, apparently by a glucocorticoid receptor-mediated process. The data in this report reveal that increased glutamine synthetase mRNA abundance is attributable at least in part to an enhanced rate of transcription of the glutamine synthetase gene. "Nuclear runoff" assays of glutamine synthetase gene expression were performed with purified myonuclei from dexamethasone-treated or untreated L6 skeletal muscle cells. These assays showed glutamine synthetase transcription to be increased approximately 2-fold as early as 1 h after incubation of cells with dexamethasone (10(-7) M); there was no increase in the rate of transcription of the beta-tubulin gene, which served as a control. The increase in glutamine synthetase gene transcription correlates with increased glutamine synthetase enzymatic activity after dexamethasone treatment. Studies with actinomycin D indicated that the half-life of glutamine synthetase mRNA (7-8 h) is not altered by dexamethasone. Therefore, the degradation of glutamine synthetase mRNA is not affected by dexamethasone, and the increased glutamine synthetase mRNA level is attributable to increased transcription. The dexamethasone-mediated increase in glutamine synthetase mRNA abundance is glucocorticoid receptor-mediated; RU38486 (a glucocorticoid receptor blocker) completely blocked the effect of dexamethasone. The dexamethasone-mediated increase in glutamine synthetase gene transcription and steady-state mRNA level was not blocked by cycloheximide, indicating a direct effect.

Herpes zoster ophthalmicus and delayed contralateral hemiparesis caused by cerebral angiitis: diagnosis and management approaches.

Four patients with herpes zoster ophthalmicus and delayed contralateral hemiparesis are described, and their findings are compared with those in patients previously reported in the English language literature. The current patients evidenced multifocal ipsilateral cerebral angiitis by angiography and multifocal infarcts in the distribution of the ipsilateral middle cerebral artery by computed tomographic scanning. Cerebrospinal fluid showed mononuclear pleocytosis, positive oligoclonal bands, and an elevated immunoglobulin G index. Two patients were treated with corticosteroids and acyclovir, and 1 with corticosteroids alone, all without apparent response. Necrotizing angiitis ipsilateral to the herpes zoster ophthalmicus was demonstrated postmortem in 1 patient with multifocal cerebral infarction and progressive leukoencephalopathy. Neither herpes varicella zoster immunocytochemical reactivity nor viral inclusions were seen. The leukoencephalopathy associated with herpes varicella zoster either may be caused by cerebral angiitis or, as previously reported, may be a temporally remote manifestation of persistent herpes varicella zoster infection. The cerebral angiitis associated with herpes varicella zoster is histologically similar to granulomatous angiitis, and both may be related to herpes varicella zoster infection of the cerebral vasculature.

Pick's disease (lobar sclerosis): depletion of neurons in the nucleus basalis of Meynert.

The nucleus basalis of Meynert (nbM) has been implicated in the pathogenesis of the presynaptic cholinergic deficiency in the cerebrum of patients with Alzheimer's disease. To further define the role of this cholinergic basal forebrain nucleus in dementia, we examined the nbM in two patients with lobar sclerosis, or Pick's disease (PD). The brains of both of these patients showed substantial reductions in the number of nerve cells in many neuronal populations, including the nbM. Our observations of the changes in the nbM are correlated with previous investigations of cholinergic markers in PD.