Crucial role of astrocytes in temporal lobe epilepsy.

Astrocytes sense and respond to synaptic activity through activation of different neurotransmitter receptors and transporters. Astrocytes are also coupled by gap junctions, which allow these cells to redistribute through the glial network the K(+) ions excessively accumulated at sites of intense neuronal activity. Work over the past two decades has revealed important roles for astrocytes in brain physiology, and it is therefore not surprising that recent studies unveiled their involvement in the etiology of neurological disorders such as epilepsy. Investigation of specimens from patients with pharmacoresistant temporal lobe epilepsy and epilepsy models revealed alterations in expression, localization and function of astrocytic connexins, K(+) and water channels. In addition, disturbed gliotransmission as well as malfunction of glutamate transporters and of the astrocytic glutamate- and adenosine-converting enzymes - glutamine synthetase and adenosine kinase, respectively - have been observed in epileptic tissues. Accordingly, increasing evidence indicates that dysfunctional astrocytes are crucially involved in processes leading to epilepsy. These new insights might foster the search for new targets for the development of new, more efficient anti-epileptogenic therapies.

Serum tumor markers in bile duct cancer--a review.

CONTEXT: Bile duct cancer (BDC) is a disease with a very grave prognosis, often diagnosed too late. OBJECTIVE: The aim of this review is to evaluate available literature on tumor markers in serum from patients with BDC. METHODS: Using the search words "serum markers", "bile duct cancer", "cholangiocarcinoma", "biomarker" and "tumor marker", a search was carried out. RESULTS: Seventy-five studies were included in the review. CONCLUSION: CA19-9 is by far the most studied and most promising diagnostic and/or prognostic marker in BDC. But also the different mucins are interesting as new markers of BDC in serum.

Prognostic significance of circulating intact and cleaved forms of urokinase plasminogen activator receptor in inoperable chemotherapy treated cholangiocarcinoma patients.

BACKGROUND: High levels of intact and cleaved forms of the urokinase-type plasminogen activator receptor (uPAR) in both tissue and blood are associated with poor survival in several cancer diseases. The prognostic significance of uPAR in cholangiocarcinoma is unknown. The aims of this study were to determine if pre-treatment serum levels of uPAR forms and a decrease in levels during chemotherapy are predictive of survival in patients with inoperable cholangiocarcinoma. DESIGN AND METHODS: Patients with inoperable cholangiocarcinoma were consecutively included in the training set (n=108). A test set included patients from a different hospital using similar treatment guidelines (n=60). Serum levels of the different uPAR forms were determined using time-resolved fluorescence immunoassays (TR-FIA). The Cox proportional hazards model was used for the uni- and multivariate survival analyses. RESULTS: Baseline level of uPAR(I-III)+uPAR(II-III) was an independent predictor of survival (HR=2.08, 95% CI:1.46-2.97, p<0.0001). Applying the linear predictor from the training set to the test set, it was validated that uPAR(I-III)+uPAR(II-III) predicted overall survival (p=0.049). A high level of uPAR(I-III)+uPAR(II-III) after 2cycles of chemotherapy was associated with poor survival (HR=1.79, 95% CI:1.08-2.97, p=0.023, n=57). This predictor, however, was not significant in the test set (p=0.21, 26 events in 27 patients). CONCLUSION: The baseline level of uPAR(I-III)+uPAR(II-III) is a predictor of survival in inoperable cholangiocarcinoma patients.

Augmentation of cognitive function by NS9283, a stoichiometry-dependent positive allosteric modulator of α2- and α4-containing nicotinic acetylcholine receptors.

BACKGROUND AND PURPOSE: Positive allosteric modulation of α4ß2 nicotinic acetylcholine (nACh) receptors could add a new dimension to the pharmacology and therapeutic approach to these receptors. The novel modulator NS9283 was therefore tested extensively. EXPERIMENTAL APPROACH: Effects of NS9283 were evaluated in vitro using fluorescence-based Ca(2+) imaging and electrophysiological voltage clamp experiments in Xenopus oocytes, mammalian cells and thalamocortical neurons. In vivo the compound was tested in models covering a range of cognitive domains in mice and rats. KEY RESULTS: NS9283 was shown to increase agonist-evoked response amplitude of (α4)(3) (ß2)(2) nACh receptors in electrophysiology paradigms. (α2)(3) (ß2)(2) , (α2)(3) (ß4)(2) and (α4)(3) (ß4)(2) were modulated to comparable extents, but no effects were detected at α3-containing or any 2α : 3ß stoichiometry nACh receptors. Native nACh receptors in thalamocortical neurons similarly displayed DHßE-sensitive currents that were receptive to modulation. NS9283 had favourable effects on sensory information processing, as shown by reversal of PCP-disrupted pre-pulse inhibition. NS9283 further improved performance in a rat model of episodic memory (social recognition), a rat model of sustained attention (five-choice serial reaction time task) and a rat model of reference memory (Morris water maze). Importantly, the effects in the Morris water maze could be fully reversed with mecamylamine, a blocker of nACh receptors. CONCLUSIONS AND IMPLICATIONS: These results provide compelling evidence that positive allosteric modulators acting at the (α4)(3) (ß2)(2) nACh receptors can augment activity across a broad range of cognitive domains, and that α4ß2 nACh receptor allosteric modulation therefore constitutes a promising therapeutic approach to symptomatic treatment of cognitive impairment.

Carcinoembryonic antigen (CEA) as tumor marker in lung cancer.

The use of CEA as a prognostic and predictive marker in patients with lung cancer is widely debated. The aim of this review was to evaluate the results from studies made on this subject. Using the search words "CEA", "tumor markers in lung cancer", "prognostic significance", "diagnostic significance" and "predictive significance", a search was carried out on PubMed. Exclusion criteria was articles never published in English, articles before 1981 and articles evaluating tumor markers in lung cancer not involving CEA. Initially 217 articles were found, and 34 were left after selecting those relevant for the present study. Four of these included both Non-Small Cell Lung Cancer (NSCLC) and Small Cell Lung Cancer (SCLC) patients, and 31 dealt solely with NSCLC patients. Regarding SCLC no studies showed that serum level of CEA was a prognostic marker for overall survival (OS). The use of CEA serum level as a prognostic marker in NSCLC was investigated in 23 studies and the use of CEA plasma level in two. In 18 (17 serum, 1 plasma) of these studies CEA was found to be a useful prognostic marker for either OS, recurrence after surgery or/and progression free survival (PFS) in NSCLC patients. Interestingly, an overweight of low stage (stage I-II) disease and adenocarcinoma (AC) patients were observed in this group. The remaining 7 studies (6 serum, 1 plasma) contained an overweight of patients with squamous carcinoma (SQ). One study found evidence for that a tumor marker index (TMI), based on preoperative CEA and CYFRA21-1 serum levels, is useful as a prognostic marker for OS in NSCLC. Six studies evaluated the use of CEA as a predictive marker for risk of recurrence and risk of death in NSCLC patients. Four of these studies found, that CEA was useful as a predictive marker for risk of recurrence and risk of death measured over time. No studies found CEA levels useful as a diagnostic marker for lung cancer. With regard to NSCLC the level of CEA measured in tumor tissue in NSCLC patients, were not of prognostic, diagnostic or predictive significance for OS or recurrence after treatment. In one study CEA level was measured in Pleural Lavage Fluid (PLF) it was here found to be useful as prognostic markers for overall survival (OS) after surgery. In conclusion serum level of CEA carries prognostic and predictive information of risk of recurrence and of death in NSCLC independent of treatment or study design. The observation that TMI index could be a potential prognostic marker for OS in NSCLC is interesting. Future studies may benefit from evaluating more than one marker at a time, which may possibly create a more precise index for prognosis and recurrence in lung cancer, than is possible by the use of single biomarkers.

Enhanced repolarization capacity: new potential antiarrhythmic strategy based on HERG channel activation.

The delayed rectifier potassium current (I(K)) is the major outward current responsible for ventricular repolarization in cardiac tissues. Based on kinetic properties and drug sensitivity it is composed of a slow (I(Ks)) and a rapid (I(Kr)) component, the latter is mediated by hERG channels. Suppression of IKr is the common mechanism of action of all class III antiarrhythmics, causing prolongation of the refractory period. However, lengthening of repolarization - either by a pathological factor or due to a pharmacological intervention - threatens with an increased risk of EAD generation and the concomitant sudden cardiac death. Therefore, a new potential anti-arrhythmic strategy, based on augmentation of the repolarization reserve, has been emerged. Recently a new class of compounds has been introduced as activators of the hERG channel. In this article we systematically review the chemical structures found to enhance IKr. Since the majority of previous experiments were performed in expression systems or in rodent cardiac preparations (neither is relevant to the human heart), in the second part of this article we present some results obtained with NS1643, the best examined hERG activator, in canine ventricular cardiomyocytes. This preparation is believed to have electrophysiological parameters most resembling those of human. NS1643 shortened the duration of canine ventricular action potential and was shown to interact with several transmembrane ion currents, including I(Ca), I(Kr), I(Ks), and I(to). However, the action potential shortening effect of NS1643 is likely related to inhibition of ICa, in addition to the enhancement of IKr. Although the multiple ion channel activity of NS1643 may carry proarrhythmic risk, the rationale of antiarrhythmic strategy based on I(Kr) activation is not questioned.

Differential effects of Kv11.1 activators on Kv11.1a, Kv11.1b and Kv11.1a/Kv11.1b channels.

BACKGROUND AND PURPOSE: K(v)11.1 channels are involved in regulating cellular excitability in various tissues including brain, heart and smooth muscle. In these tissues, at least two isoforms, K(v)11.1a and K(v)11.1b, with different kinetics, are expressed. K(v)11.1 activators are potential therapeutic agents, but their effects have only been tested on the K(v)11.1a isoform. In this study, the effects of two different K(v)11.1 activators, NS1643 and RPR260243, were characterized on K(v)11.1a and K(v)11.1b channels. EXPERIMENTAL APPROACH: K(v)11.1a and K(v)11.1b channels were expressed in Xenopus laevis oocytes, and currents were measured using two-electrode voltage clamp. I/V curves and channel kinetics were measured before and after application of 30 µM NS1643 or 10 µM RPR260243. KEY RESULTS: NS1643 increased steady-state currents through Kv11.1b several fold more than through K(v)11.1a channels, without affecting EC(50) values. NS1643 increased activation rates and decreased rates of inactivation, recovery from inactivation and deactivation for both channels. Except for activation, where effect of NS1643 was comparable, relative changes were greater for Kv11.1b than for K(v)11.1a. RPR260243 increased steady-state currents only through Kv11.1a channels, but slowed the process of deactivation for both channels primarily by decreasing time constant of slow deactivation. This effect was greater on K(v)11.1b than on K(v)11.1a. Effects of both compounds on heteromeric K(v)11.1a/K(v)11.1b channels were similar to those on K(v)11.1a. CONCLUSIONS AND IMPLICATIONS: Both NS1643 and RPR260243 displayed differential effects on K(v)11.1a and K(v)11.1b channels, the effects being relatively more pronounced on K(v)11.1b channels. This affirms the importance of testing the effect of K(v)11.1 activators on different channel isoforms.

Repolarization of the cardiac action potential. Does an increase in repolarization capacity constitute a new anti-arrhythmic principle?

The cardiac action potential can be divided into five distinct phases designated phases 0-4. The exact shape of the action potential comes about primarily as an orchestrated function of ion channels. The present review will give an overview of ion channels involved in generating the cardiac action potential with special emphasis on potassium channels involved in phase 3 repolarization. In humans, these channels are primarily K(v)11.1 (hERG1), K(v)7.1 (KCNQ1) and K(ir)2.1 (KCNJ2) being the responsible alpha-subunits for conducting I(Kr), I(Ks) and I(K1). An account will be given about molecular components, biophysical properties, regulation, interaction with other proteins and involvement in diseases. Both loss and gain of function of these currents are associated with different arrhythmogenic diseases. The second part of this review will therefore elucidate arrhythmias and subsequently focus on newly developed chemical entities having the ability to increase the activity of I(Kr), I(Ks) and I(K1). An evaluation will be given addressing the possibility that this novel class of compounds have the ability to constitute a new anti-arrhythmic principle. Experimental evidence from in vitro, ex vivo and in vivo settings will be included. Furthermore, conceptual differences between the short QT syndrome and I(Kr) activation will be accounted for.

Dual-function vector for protein expression in both mammalian cells and Xenopus laevis oocytes.

Both Xenopus laevis oocytes and mammalian cells are widely used for heterologous expression of several classes of proteins, and membrane proteins especially, such as ion channels or receptors, have been extensively investigated in both cell types. A full characterization of a specific protein will often engage both oocytes and mammalian cells. Efficient expression of a protein in both systems have thus far only been possible by subcloning the cDNA into two different vectors because several different molecular requirements should be fulfilled to obtain a high protein level in both mammalian cells and oocytes. To address this problem, we have constructed a plasmid vector, pXOOM, that can function as a template for expression in both oocytes and mammalian cells. By including all the necessary RNA stability elements for oocyte expression in a standard mammalian expression vector, we have obtained a dual-function vector capable of supporting protein production in both Xenopus oocytes and CHO-K1 cells at an expression level equivalent to the levels obtained with vectors optimized for either oocyte or mammalian expression. Our functional studies have been performed with hERGI, KCNQ4, and Kv1.3 potassium channels.

Adult-onset MLD: a gene mutation with isolated polyneuropathy.

A 22-year-old man presented with recurrent ulnar mononeuropathies and diffusely slow nerve conduction velocities. Arylsulfatase A (ASA) activity from leukocytes and fibroblasts was reduced, and urinary sulfatides were increased. Sural nerve biopsy revealed a reduction in myelinated fibers and Schwann cell inclusions. Results of studies of CNS integrity, including cranial MRI, evoked potentials, and neuropsychologic tests, were normal. Molecular genetic analyses revealed a novel homozygous missense mutation (Thr286Pro) in the ASA gene.

Correlation of tumor p53 and PCNA with response and survival of glioblastoma in patients treated with an ECOG protocol of pre-irradiation chemotherapy.

BACKGROUND: The ability to predict treatment responsiveness and survival of patients with glioblastoma multiforme, the most malignant and most common primary brain tumor, would be a valuable asset. Tumor and proliferation markers such as p53 and PCNA have been immunohistochemically defined and have been useful in other tumors in determining prognosis. Therefore, the authors studied the correlation of responsiveness to treatment, time to progression and survival with p53 and PCNA labeling indices in a pre-irradiation chemotherapy study of the glioblastoma multiforme. METHODS: Immunohistopathology for labeling indices for p53 and PCNA using formalin-fixed, paraffin-embedded tissue from the glioblastomas of 23 patients entered into a phase II ECOG trial of pre-irradiation chemotherapy were defined using the streptavidin-peroxidase technique with AEC chromogen. The labeling indices were correlated with response to treatment time to progression and overall survival. Most patients received three cycles of BCNU for three days over three months and cisplatin monthly for three days over three months prior to external beam irradiation. RESULTS: There were no significant differences in treatment response, time to progression or overall survival in glioblastoma, patients with positive p53 labeling index (> 5%) versus a negative p53 labeling index (< or = 5%) or positive PCNA labeling (> 10%) versus a negative labeling index (< or = 10%) or any combination of P53 and PCNA labeling indices. CONCLUSIONS: Using this protocol of pre-irradiation chemotherapy, p53 and PCNA labeling indices in the glioblastoma multiforme did not predict treatment benefit.

A phase II study of preradiation chemotherapy followed by external beam radiotherapy for the treatment of patients with newly diagnosed glioblastoma multiforme: an Eastern Cooperative Oncology Group study (E2393).

Recent publications support the use of preradiation chemotherapy in the treatment of selected primary brain tumors. In the pediatric population, this treatment strategy often delays radiotherapy and may improve the outcome in patients. This manuscript describes the use of a preradiation chemotherapy approach for adult patients with newly diagnosed glioblastoma multiforme. The main objective of this trial was to determine the feasibility of delivering up to 3 monthly cycles of a 72 h continuous simultaneous intravenous infusion of BCNU (40 mg/m2/day) and cisplatin (40 mg/m2/day). Patients were evaluated for tumor response or progression after each cycle. Following the completion of the chemotherapy treatments or evidence of tumor progression, patients underwent external beam radiotherapy. A dose of 45 Gy was delivered to the pretreatment tumor volume plus surrounding edema and a margin of 3.0 cm. An additional 14.4 Gy was delivered to the preoperative volume plus a 2 cm margin. Fifty patients were enrolled, 47 were eligible and analyzable. Overall, 79% of patients were able to complete at least 2 cycles of treatment, exceeding the predefined measure of feasibility. One patient achieved a complete response, 10 patients a partial response and 18 patients had stable disease at completion of the chemotherapy treatments. Twenty-four patients experienced grade 4 toxicity, mostly hematologic. All patients were able to undergo radiotherapy following chemotherapy. These results indicate that a preradiation strategy is feasible. Although responses to the chemotherapy were seen, a phase III trial is needed to determine whether this approach provides an advantage over standard treatment; such a phase III trial has been undertaken by ECOG.

Angiogenesis and neuroblastomas: interleukin-8 and interleukin-8 receptor expression in human neuroblastoma.

PURPOSE: Studies have demonstrated that the pro-angiogenic cytokine interleukin-8 (IL-8) and the IL-8 receptors likely have a role in the growth and metastasis of various solid tumors. We hypothesized that in vivo neuroblastoma expresses IL-8 and the IL-8 receptors A and B, and that factors known to regulate IL-8 expression are present and active in the neuroblastoma microenvironment. MATERIALS AND METHODS: To confirm the presence of IL-8/IL-8 receptors in neuroblastoma, immunohistochemical analysis for IL-8 and its receptors was performed on 10 archival specimens, including benign adrenal and well to poorly differentiated neuroblastoma samples. Immunohistochemical analysis was also performed for interleukin-1beta (IL-1beta) and tumor necrosis factor-alpha. Cultured neuroblastoma cells SK-N-MC and SK-N-SH were stimulated with 10 ng./ml. IL-1beta or tumor necrosis factor-alpha and control media (15 each). Cell culture supernatants were analyzed with enzyme-linked immunosorbant assay for IL-8 levels at 24 and 48 hours. RESULTS: Minimal expression of IL-8 was noted in benign adrenal tissue but expression for IL-8 was present in all neuroblastoma specimens. Microvessel staining was present in 30% of the specimens. All tumor specimens expressed IL-8 receptor B, and both receptors were expressed in the tumor microvasculature. Immunohistochemical analysis confirmed the presence of IL-1beta and tumor necrosis factor in the neuroblastoma microenvironment. In vitro studies demonstrated that SK-N-MC and SK-N-SH cells express low levels of IL-8 under normal conditions and that IL-1beta and tumor necrosis factor-alpha significantly increased expression of IL-8 at 24 and 48 hours. CONCLUSIONS: Our results indicate that IL-8 and its receptors are expressed in neuroblastoma tumor specimens. In addition, the fact that IL-1beta and tumor necrosis factor-alpha are expressed in the neuroblastoma microenvironment combined with our in vitro results suggests that these cytokines may be involved in in vivo regulation of IL-8 in human neuroblastoma. Understanding the angiogenic factors and regulatory cascade promoting angiogensis in neuroblastoma may lead to the development of effective anti-angiogenic strategies.

Quantification and distribution of Ca(2+)-activated maxi K(+) channels in rabbit distal colon.

The Ca(2+)-activated maxi K(+) channel is an abundant channel type in the distal colon epithelium, but nothing is known regarding the actual number and precise localization of these channels. The aim of this study has therefore been to quantify the maxi K(+) channels in colon epithelium by binding of iberiotoxin (IbTX), a selective peptidyl ligand for maxi K(+) channels. In isotope flux measurements 75% of the total K(+) channel activity in plasma membranes from distal colon epithelium is inhibited by IbTX (K(0.5) = 4.5 pM), indicating that the maxi K(+) channel is the predominant channel type in this epithelium. Consistent with the functional studies, the radiolabeled double mutant (125)I-IbTX-D19Y/Y36F binds to the colon epithelium membranes with an equilibrium dissociation constant of approximately 10 pM. The maximum receptor concentration values (in fmol/mg protein) for (125)I-IbTX-D19Y/Y36F binding to colon epithelium are 78 for surface membranes and 8 for crypt membranes, suggesting that the maxi K(+) channels are predominantly expressed in the Na(+)-absorbing surface cells, as compared with the Cl(-)-secreting crypt cells. However, aldosterone stimulation of this tissue induced by a low-Na(+) diet does not change the total number of maxi K(+) channels.

Broad immunocytochemical localization of the formylpeptide receptor in human organs, tissues, and cells.

The formylpeptide receptor (FPR), previously found only on polymorphonuclear leukocytes and monocytes/macrophages, responds to both synthetic N-formyl oligopeptides and those produced by bacteria. The cDNA for human FPR has been cloned and a rabbit polyclonal antiserum directed against a synthetic 11-amino-acid peptide corresponding to the deduced carboxy-terminus has been produced. We have now extensively characterized and used the antibody to detect FPR on normal human tissues and cell types. The receptor antigen is present on some epithelial cells, especially those with a secretory function, and on some endocrine cells, e.g., follicular cells of the thyroid and cortical cells of the adrenal. Liver hepatocytes and Kupffer cells are positive. Smooth muscle and endothelial cells are also generally positive. In the brain and spinal cord, the neurons of the motor, sensory, and cerebellar systems, and those of the parasympathetic and sympathetic systems stain positively. These data suggest that the putative endogenous agonist for FPR or an antigenically similar receptor reacts with cellular targets in the neuromuscular, vascular, endocrine, and immune systems.

A therapeutic trial of radiation therapy with Vincristine, etoposide, and Procarbazine (VVP) in high grade intracranial gliomas--an Eastern Cooperative Oncology Group Study (E2392).

This study is a combined modality Phase II therapeutic trial to determine the efficacy of the novel combination of VP-16, Vincristine and Procarbazine in addition to postoperative radiation therapy in patients with high grade intracranial gliomas. Thirty three patients (median age 51 years) were entered (27 with glioblastoma multiforme, 6 with anaplastic astrocytoma). Toxicity was manageable with no lethal toxicities. Five of seven life threatening toxicities were hematologic. Median overall survival was 14.2 months. These data suggest this regimen is effective treatment for patients with high grade gliomas.

The generation of encephalitogenic T cell lines from experimental allergic encephalomyelitis-resistant strains of mice.

While only a few strains of mice are susceptible to the primary induction or passive transfer of experimental allergic encephalomyelitis (EAE), the basis of EAE resistance remains unclear. In the present studies, we have defined two approaches that allow for the generation of encephalitogenic, myelin basic protein-reactive, T cell lines from EAE-resistant strains of mice. The first approach, based on the putative relevance of apoptosis to autoimmune disease, involves repeat antigenic stimulation of recently initiated T cell lines. The second approach involves the initiation of lymph node cultures in the absence of exogenous splenocytes as antigenic-presenting cells and the use of a higher antigen concentration. Both approaches lead to the generation of encephalitogenic T cell lines from EAE-resistant mouse strains and will be useful for identifying factors relevant to the pathogenesis of EAE.

Autosomal dominant centronuclear myopathy: report of a new family with clinical features simulating facioscapulohumeral syndrome.

The centronuclear myopathies are a clinically and genetically heterogeneous group of disorders which share similar histological features on muscle biopsy. The familial cases have been classified genetically as X-linked or autosomal in inheritance. The autosomal forms usually have a later onset and milder course as compared to the X-linked form. Thirteen families with autosomal dominant centronuclear myopathy have been previously described. We describe an additional family with unique clinical features which initially suggested a facioscapulohumeral syndrome.

Selective atrophy of type 1 muscle fibers in McArdle's disease.

McArdle's disease is a metabolic myopathy of glycogen utilization caused by an absence or deficiency of myophosphorylase. The muscle biopsy features include increased deposition of subsarcolemmal glycogen and absent phosphorylase histochemical staining of myofibers. We report the clinical and unique pathologic findings in three cases of McArdle's disease with prominent type 1 fiber atrophy.