Treatment of relapsing multiple sclerosis in Hungary - consensus recommendation from the Hungarian neuroimmunology society

Multiple sclerosis (MS) may impact quality of life, careers and family plans of the affected individuals. The current treatments with disease modifying therapies aim to prevent people with MS (pwMS) from disability accumulation and progression. Different countries have different reimbursement policies resulting in inequalities in patient care among geographical regions. Access to anti-CD20 therapies for relapsing MS is restricted in Hungary because therapy of individual cases only is reimbursed. In the light of the latest research and national guidelines, 17 Hungarian MS experts agreed on 8 recommendations regarding relapsing pwMS using the Delphi round method. Strong agreement (> 80%) was achieved in all except one recommendation after three rounds, which generated a fourth Delphi round. The experts agreed on treatment initiation, switch, follow-up and discontinuation, as well as on special issues such as pregnancy, lactation, elderly population, and vaccination. Well-defined national consensus protocols may facilitate dialogue between policymakers and healthcare professionals and thus contribute to better patient care in the long run.

Investigation of oxidative stress in patients with multifocal motor neuropathy

Multifocal motor neuropathy (MMN) is a rare, immune-mediated illness attacking ex­clusively motor nerves. It is known that oxidative stress is present in peripheral neuropathies, but it has not been investigated MMN. We measured in our prospective study the L-arginine, symmetric and asymmetric dimethylarginine (SDMA, ADMA) serum concentrations of 10 patients and 10 controls before and after intravenous immunoglobulin treatment (IVIG), as markers of the L-arginine/NO pathway involved in chronic inflammation and oxidative stress. The functions of motor nerves were tested in all patients and the serum antiganglioside antibody levels were de­tec­ted, as well. MMN patients showed significantly higher ADMA (p = 0.0048; 0.98 and 0.63, respectively) and SDMA le­vels (p = 0.001; 0.88 and 0.51, respectively) than healthy controls, while L-arginine was not different. Controlling for the covariant age, ADMA (B = -0.474; p = 0.041) or SDMA (B = -0.896; p < 0.0005) serum levels proved to be the significant predictors of the presence of MMN. IVIG therapy decreased significantly ADMA concentrations (p = 0.025; 0.98 and 0.84, respectively) and showed a trend to reduce SDMA levels (p = 0.1; 0.88 and 0.74, respectively). The dimethylamine levels did not correlate with the number of affected nerves, disease duration, or the presence of ganglioside antibodies. The conduction block-related peripheral motor dysfunction improved right after the IVIG treatment. Dimethylamine levels are elevated in the serum and are responsive to IVIG therapy in MMN. These findings support the presence of oxidative stress in MMN.

[Paradigm shift in management of patients with vertigo and imbalance]

Dizziness is one of the most common causes of medical visits. Management of the dizzy patient may be challenging both for the general practitioner, in emergency departments, and special clinics, as behind a seemingly homogeneous clinical presentation several very different etiologies may occur. Research of the last two century enriched our knowledge about physiology and pathophysiology of the vestibular system. Much knowledge is now available about the labyrinth being able to sense head motions and gravity, processing of afferent vestibular stimuli, reflectory oculomotor and postural control, or recovery of the vestibular system. Based on scientific results new beside tests have been introduced including provocation maneuvers for detecting ectopic otoliths in different semicircular canals, head impulse test to examine function of the vestibulo-ocular reflex, and the HINTS+ battery for differentiation of peripheral or central origin of an acute vestibular syndrome. Technical innovations like videooculography and vestibular evoked myogenic potentials enable us to selectively and side-specifically examine the function of all six semicircular canals and two otolith organs. Pathomechanism of disorders with vertigo and dizziness became more clear resulting in the development or amendment of diagnostic criteria of several vestibular disorders including vestibular migraine, Menière's disease, benign paroxysmal positional vertigo, persistent postural-perceptual dizziness, bilateral vestibulopathy. Broader knowledge about the pathomechanism promoted the development of new therapeutic methods like different repositioning maneuvers in benign paroxysmal positional vertigo, pharmaceutical therapies, vestibular rehabilitation, and psychotherapy. We aimed to summarize the novelties in the field of oto-neurology.

[Emergency diagnosis of the acute vestibular syndrome]

INTRODUCTION AND AIM

To diagnose acute vestibular syndrome (AVS) in a prospective study by a new bedside test (providing 1A evidence) based on oculomotor analysis and assessment of hearing loss. To assess the frequency of central and peripheral causes of acute vestibular syndrome in the emergency room. To establish the diagnostic accuracy of acute cranial computed tomography as compared to oculomotor analysis done by video oculography goggles and audiometry.

METHOD

Between 1st March 2016 and 1st March 2017 we documented 125 patients (62 women, 63 men, average age 53 years) in the emergency room of the Petz Aladár County Teaching Hospital using the above bedside and instrumental testing. Diagnosis was verified by cranial magnetic resonance imaging.

RESULTS

According to the results of the instrumental examination in AVS in 67% we found a peripheral cause and in 33% a central pathology. In 62% isolated posterior circulation stroke manifested itself by isolated vertigo without additional focal signs and the acute cranial computed tomography showed negative results in 96%. The instrumental examination increased diagnostic accuracy by making the diagnosis of isolated inferior semicircular canal vestibular neuritis possible.

CONCLUSIONS

The new bedside oculomotor test is suitable for the diagnosis of posterior circulation stroke manifesting with isolated vertigo in early cases, when the routine neuroradiologic methods have a lower sensitivity or are not available. Orv Hetil. 2017; 158(51): 2029-2040.

Changes to the septo-fornical area might play a role in the pathogenesis of anxiety in multiple sclerosis

BACKGROUND

Reports on the relationships between white matter lesion load (WMLL) and fatigue and anxiety in multiple sclerosis (MS) are inconsistent.

OBJECTIVE

To investigate the association of total and tract-specific WMLL with fatigue and anxiety.

METHODS

Total and regional T2 WMLL was assessed for 19 tracts in 48 MS patients (30 females). ICBM-DTI-81 Atlas-based parcellation was combined with WMLL segmentation of T2-weighted magnetic resonance imaging (MRI). Fatigue, anxiety, and depression were assessed using Fatigue Impact Scale, State Trait Anxiety Inventory, and Beck Depression Inventory, respectively.

RESULTS

Fatigue, anxiety, and depression showed significant inter-correlation. We found no association between fatigue and total or regional WMLLs, whereas anxiety was associated with total and regional WMLLs in nine tracts. After adjusting for total WMLL, age, and depression, only the column and body of the fornix (CBF) remained significantly associated with anxiety. Post hoc analyses showed no CBF lesions on T1-weighted MRI and suggested, but could not confirm, that the septum pellucidum might play a role in the pathogenesis of anxiety.

CONCLUSION

Our results suggest that anxiety in MS patients may have a neuropathological substrate in the septo-fornical area, which requires further validation using larger sample size and ultra-high-field MRI in targeted prospective studies.

[Magnetic resonance imaging in the course of alemtuzumab and teriflunomide therapy]

Our work aimed to review the published results of magnetic resonance imaging (MRI) obtained in the course of alemtuzumab and teriflunomide therapy in multiplex sclerosis. In multiplex sclerosis MRI sensitively detects subclinical pathological processes, which do not manifest clinically in the early course of the disease, however have substantial significance from the viewpoint of the long-term disease prognosis. MRI has an increasingly important role in the early monitoring of the therapeutic efficacy. In the last 15 years several clinical trials have been conducted with alemtuzumab and teriflunomide in multiple sclerosis providing evidence about the favourable clinical effect of these drugs. MRI images were acquired in these trials as well, and the results published recently in the scientific literature. These MRI results denote the suppression of the disease activity and the neurodegenerative processes, which may imply a favourable effect on the long-term prognosis of the disease.

[MENTALIZING DEFICIT IN NEUROLOGICAL DISORDERS: A REVIEW ARTICLE]

INTRODUCTION

Mentalization is the ability to attribute mental states (intentions, desires, thoughts, emotions) to others, and hence to predict their behaviour. This ability fundamentally determines our participation in social relationships and adaptation to society. A significant proportion of the disorders of the central nervous system (CNS) affects those brain structures and neurotransmitter systems that play a role in the mentalizing processes. Accordingly, a number of CNS disorders may be associated with mentalizing deficits, which may affect the outcome of these diseases. Here, we review recent research on mentalizing abilities in neurological diseases.

METHODS

An internet database search was performed to identify publications on the subject.

RESULTS

Sixty-two publications in English corresponded to the search criteria. These publications reported impaired mentalization in several neurological disorders (e.g. epilepsy, Parkinson's disease, multiple sclerosis, dementias, traumatic brain injury).

DISCUSSION

The results indicate that a number of neurological disorders associate with mentalizing deficit. This deficit is often present in the early stages of the diseases and has a prognostic value, which in turn emphasizes the importance of the early detection and adequate rehabilitation.

Disconnection mechanism and regional cortical atrophy contribute to impaired processing of facial expressions and theory of mind in multiple sclerosis: a structural MRI study

Successful socialization requires the ability of understanding of others' mental states. This ability called as mentalization (Theory of Mind) may become deficient and contribute to everyday life difficulties in multiple sclerosis. We aimed to explore the impact of brain pathology on mentalization performance in multiple sclerosis. Mentalization performance of 49 patients with multiple sclerosis was compared to 24 age- and gender matched healthy controls. T1- and T2-weighted three-dimensional brain MRI images were acquired at 3Tesla from patients with multiple sclerosis and 18 gender- and age matched healthy controls. We assessed overall brain cortical thickness in patients with multiple sclerosis and the scanned healthy controls, and measured the total and regional T1 and T2 white matter lesion volumes in patients with multiple sclerosis. Performances in tests of recognition of mental states and emotions from facial expressions and eye gazes correlated with both total T1-lesion load and regional T1-lesion load of association fiber tracts interconnecting cortical regions related to visual and emotion processing (genu and splenium of corpus callosum, right inferior longitudinal fasciculus, right inferior fronto-occipital fasciculus, uncinate fasciculus). Both of these tests showed correlations with specific cortical areas involved in emotion recognition from facial expressions (right and left fusiform face area, frontal eye filed), processing of emotions (right entorhinal cortex) and socially relevant information (left temporal pole). Thus, both disconnection mechanism due to white matter lesions and cortical thinning of specific brain areas may result in cognitive deficit in multiple sclerosis affecting emotion and mental state processing from facial expressions and contributing to everyday and social life difficulties of these patients.

Identification and clinical impact of multiple sclerosis cortical lesions as assessed by routine 3T MR imaging

BACKGROUND AND PURPOSE

Histopathologic studies have reported widespread cortical lesions in MS; however, in vivo detection by using routinely available pulse sequences is challenging. We investigated the relative frequency and subtypes of cortical lesions and their relationships to white matter lesions and cognitive and physical disability.

MATERIALS AND METHODS

Cortical lesions were identified and classified on the basis of concurrent review of 3D FLAIR and 3D T1-weighted IR-SPGR 3T MR images in 26 patients with MS. Twenty-five patients completed the MACFIMS battery. White matter lesion volume, cortical lesion number, and cortical lesion volume were assessed.

RESULTS

Overall, 249 cortical lesions were detected. Cortical lesions were present in 24/26 patients (92.3%) (range per patient, 0-30; mean, 9.6 ± 8.8). Most (94.4%, n = 235) cortical lesions were classified as mixed cortical-subcortical (type I); the remaining 5.6% (n = 14) were classified as purely intracortical (type II). Subpial cortical lesions (type III) were not detected. White matter lesion volume correlated with cortical lesion number and cortical lesion volume (r(S) = 0.652, r(S) = 0.705, respectively; both P < .001). After controlling for age, depression, and premorbid intelligence, we found that all MR imaging variables (cortical lesion number, cortical lesion volume, white matter lesion volume) correlated with the SDMT score (R(2) = 0.513, R(2) = 0.449, R(2) = 0.418, respectively; P < .014); cortical lesion number also correlated with the CVLT-II scores (R(2) = 0.542-0.461, P < .043). The EDSS scores correlated with cortical lesion number and cortical lesion volume (r(S) = 0.472, r(S) = 0.404, respectively; P < .05), but not with white matter lesion volume.

CONCLUSIONS

Our routinely available imaging method detected many cortical lesions in patients with MS and was useful in their precise topographic characterization in the context of the gray matter-white matter junction. Routinely detectable cortical lesions were related to physical disability and cognitive impairment.

Binding of sodium channel inhibitors to hyperpolarized and depolarized conformations of the channel

Sodium channels are inhibited by a chemically diverse group of compounds. In the last decade entirely new structural classes with superior properties have been discovered, and novel therapeutic uses of sodium channel inhibitors (SCIs) have been suggested. Many promising novel drug candidates have been described and characterized. Published structure-activity relationship studies, pharmacophore models, and mutagenesis studies seem to lag behind, dealing with only a limited group of inhibitor compounds. The abundance of novel compounds requires an organized comparison of drug potencies. The affinity of sodium channel inhibitors can vary typically ten- to thousand-fold depending on the voltage protocol; therefore comparison of electrophysiology data is difficult. In this study we describe a method for standardization of these data with the help of a simple model of state-dependence. We derived hyperpolarized (resting) and depolarized (generally termed "inactivated") state affinities for the studied drugs, which made the measurements comparable. We show a rank order of SCIs based on resting and inactivated affinity values. In an attempt to define basic chemical requirements for sodium channel inhibitor activity we investigated the dependence of both resting and inactivated state affinities on individual chemical descriptors. Lipophilicity (most often expressed by the logP value) is the single most important determinant of SCI potency. We investigated the independent impact of several other calculated chemical properties by standardizing drug potencies for logP values. By combining these two approaches: standardization of affinity values, and standardization of potencies, we concluded that while resting affinity is mostly determined by lipophilicity, inactivated state affinity is determined by a more complex interaction of chemical properties, including hydrogen bond acceptors, aromatic rings, and molecular weight.

Non-synaptic receptors and transporters involved in brain functions and targets of drug treatment

Beyond direct synaptic communication, neurons are able to talk to each other without making synapses. They are able to send chemical messages by means of diffusion to target cells via the extracellular space, provided that the target neurons are equipped with high-affinity receptors. While synaptic transmission is responsible for the 'what' of brain function, the 'how' of brain function (mood, attention, level of arousal, general excitability, etc.) is mainly controlled non-synaptically using the extracellular space as communication channel. It is principally the 'how' that can be modulated by medicine. In this paper, we discuss different forms of non-synaptic transmission, localized spillover of synaptic transmitters, local presynaptic modulation and tonic influence of ambient transmitter levels on the activity of vast neuronal populations. We consider different aspects of non-synaptic transmission, such as synaptic-extrasynaptic receptor trafficking, neuron-glia communication and retrograde signalling. We review structural and functional aspects of non-synaptic transmission, including (i) anatomical arrangement of non-synaptic release sites, receptors and transporters, (ii) intravesicular, intra- and extracellular concentrations of neurotransmitters, as well as the spatiotemporal pattern of transmitter diffusion. We propose that an effective general strategy for efficient pharmacological intervention could include the identification of specific non-synaptic targets and the subsequent development of selective pharmacological tools to influence them.

A component of polysaccharide peptidoglycan complex on Lactobacillus induced an improvement of murine model of inflammatory bowel disease and colitis-associated cancer

Interleukin-6 (IL-6)/signal transducer and activator of transcription 3 (STAT3) signals play key roles in the pathogenesis of inflammatory bowel disease (IBD). We previously described that both intact cells and a cell wall-derived polysaccharide-peptidoglycan complex (PSPG) in a strain of lactobacillus [Lactobacillus casei Shirota (LcS)] inhibited IL-6 production in lipopolysaccharide (LPS)-stimulated lamina propria mononuclear cells (LPMCs) isolated from murine IBD. Diets with LcS improve murine IBD by suppression of IL-6 synthesis in LPMCs. Moreover, LcS supplementation with fermented milk ameliorates disease activity in patients with active ulcerative colitis. Here, we focused on the specific roles of PSPG in LcS concerning their anti-inflammatory actions. PSPG derived from LcS, and no other strain of lactobacilli, inhibited IL-6 production in LPS-stimulated murine IBD LPMCs. Purified PSPG-I from LcS inhibited IL-6 synthesis in LPS-stimulated murine IBD LPMCs through the inhibition of nuclear factor-kappaB. The anti-IL-6 action of LcS PSPG was abrogated by masking with monoclonal anti-PSPG-I. Furthermore, PSPG-I-negative L. casei strains (PSPG-I-negative mutant LcS: LC(DeltaPSPG-I), L. casei ATCC 334) did not inhibit IL-6 production. Finally, we confirmed the effects of PSPG-I on LcS in the models of both IBD and colitis-associated cancer (CAC). In the IBD model, ingestion of LcS improved ileitis and inhibited activation of IL-6/STAT3 signaling, while ingestion of the LC(DeltaPSPG-I) strain did not. In the CAC model, treatment with LcS, but not the LC(DeltaPSPG-I) strain, showed tumour-suppressive effects with an inhibition of IL-6 production in the colonic mucosa. These results suggested that a specific polysaccharide component in an L. casei strain plays a crucial role in its anti-inflammatory actions in chronic intestinal inflammatory disorders.

Morphometric changes of gray matter in Parkinson's disease with depression: a voxel-based morphometry study

The origin of the high rate of depression in idiopathic Parkinson's disease (PD) is unknown. We applied voxel-based morphometry (VBM), as a sensitive tool in detection of gray matter MR density alterations, to find differences in depressed and nondepressed PD patients. Patients with idiopathic PD were classified into depressed (DPD) and nondepressed (NDPD) groups based on the Montgomery-Asberg Depression Rating Scale (MADRS). Subsequently, a group comparisons were performed between depressed PD (n = 23), nondepressed PD (n = 27) and normal healthy controls (NC, n = 16). There was no difference in gray matter density comparing healthy controls to any PD groups. However, when NDPD and DPD cohorts were compared, density alteration of the bilateral orbitofrontal, bilateral rectal gyrus, and also the right superior temporal pole was detected in the depressed subgroup. Exploratory analyses revealed an inverse correlation of MADRS scores and severity of VBM alteration in these regions beside the right medial temporal gyrus, anterior and medial cingular gyrus, and parahippocampal gyrus. These results suggest that depression in PD is related to gray matter decrease in the bilateral orbitofrontal and right temporal regions as well as the limbic system.

Follow-up of vestibular function in bilateral vestibulopathy

OBJECTIVE

Bilateral vestibulopathy (BV) leads to a bilateral deficit of the vestibulo-ocular reflex and has various aetiologies. The main goal of this study was to determine the frequency and degree of recovery or worsening of vestibular function over time.

METHODS

82 patients (59 males, 23 females; mean age at the time of diagnosis 56.3 (SD 17.6) years) were re-examined 51 (36) months after the first examination. All patients underwent a standardised neuro-ophthalmological and neuro-otological examination. Electronystagmography with bithermal caloric irrigation was analysed by measurement of the mean peak slow phase velocity (SPV) of the induced nystagmus. Patients evaluated the course of their disease in terms of balance, gait unsteadiness and health related quality of life.

RESULTS

Statistical analysis of the mean peak SPV of caloric induced nystagmus revealed a non-significant worsening over time (initial mean peak SPV 3.0 (3.5) degrees/s vs 2.1 (2.8) degrees/s). With respect to subgroups of aetiology, only patients with BV due to meningitis exhibited an increasing, but non-significant SPV (1.0 (1.4) degrees/s vs 1.9 (1.6) degrees/s). Vestibular outcome was independent of age, gender, time course of manifestation and severity of BV. Single analysis of all patients showed that a substantial improvement > or = 5 degrees/s occurred in two patients on both sides (idiopathic n = 1, Sjögren's syndrome n = 1) and in eight patients on one side (idiopathic n = 6, meningitis n = 1, Menière's disease n = 1). In 84% of patients there was impairment of their health related quality of life (42% slight, 24% moderate, 18% severe). Forty-three per cent of patients rated the course of their disease as stable, 28% as worsened and 29% as improved.

CONCLUSIONS

Our data support the view that more than 80% of patients with BV do not improve. Thus the prognosis of BV is less favourable than assumed.

Susac’s syndrome: clinical characteristics of a Hungarian case

A Susac-szindróma ritka, többszörös szervi érintettséggel járó kórkép, melyet encephalopathiából, a retinát ellátó artéria ágainak okklúziójából és halláscsökkenésből álló triász jellemez. Ritka előfordulása, fluktuáló lefolyása és a hosszabb-rövidebb ideig inkomplett klinikai kép miatt sokszor nem ismerik fel, pedig az időben megkezdett kezelés a prognózist kedvezően befolyásolja. Módszer: Közleményünkben egy beteg esetét ismertetjük, és összefoglaljuk a kórkép legfontosabb ismérveit, diagnosztikai és terápiás lehetőségeit. Eredmények: A 30 éves nőbeteg ismeretlen eredetű encephalopathia, napok alatt kialakuló személyiségváltozás, meglassult gondolkodás, indítékhiány miatt került a pszichiátriai, majd a neurológiai klinikánkra. A koponya MR-vizsgálata multiplex fehérállományi laesiókat, liquorvizsgálata emelkedett összfehérjét mutatott. Az anamnézisben szereplő ismétlődő kétoldali látászavar, halláscsökkenés és migrénes fejfájás az encephalopathiával együtt a fiatal nőbeteg esetében Susac-szindróma lehetőségét vetette fel. Az immunszerológiai vizsgálatok szisztémás kötőszöveti betegséget nem jeleztek, a thrombophilia irányában végzett vizsgálatok negatívak voltak. A fundoszkópia és a fluoreszcens angiográfia a retinaerek többszörös okklúzióját, az audiogram kétoldali típusos halláscsökkenést mutatott. A liquor vizsgálata a szindrómára jellemző összfehérje-emelkedést jelezte. A krónikus szteroidterápia a tünetek regresszióját eredményezte. Következtetések: Egy magyar eset ismertetésével célunk ráirányítani a figyelmet egy olyan ritka kórképre, melynél az interdiszciplináris gondolkodás a klinikai diagnózis alapvető része.

The Mechanism of Activity-Dependent Sodium Channel Inhibition by the Antidepressants Fluoxetine and Desipramine

The effect of monoamine uptake inhibitor-type antidepressants on sodium channels of hippocampal neurons was investigated. Members of the tricyclic group of antidepressants are known to modify multiple targets, including sodium channels, whereas selective serotonin-reuptake inhibitors (SSRIs) are regarded as highly selective compounds, and their effect on sodium channels was not investigated in detail. In this study, a representative member of each group was chosen: the tricyclic antidepressant desipramine and the SSRI fluoxetine. The drugs were roughly equipotent use-dependent inhibitors of sodium channels, with IC(50) values approximately 100 microM at -150 mV holding potential, and approximately 1 microM at -60 mV. We suggest that therapeutic concentrations of antidepressants affect neuronal information processing partly by direct, activity-dependent inhibition of sodium channels. As for the mechanism of inhibition, use-dependent inhibition by antidepressants was believed to be due to a preferential affinity to the fast-inactivated state. Using a voltage and perfusion protocol by which relative affinities to fast-versus slow-inactivated states could be assessed, we challenged this view and found that the affinity of both drugs to slowinactivated state(s) was higher. We propose a different mechanism of action for these antidepressants, in which slow rather than fast inactivation plays the dominant role. This mechanism is similar but not equivalent with the novel mechanism of usedependent sodium channel inhibition previously described by our group (Neuroscience 125:1019-1028, 2004; Neuroreport 14:1945-1949, 2003). Our results suggest that different drugs can produce use-dependent sodium channel inhibition by different mechanisms.

A novel modulatory mechanism of sodium currents: frequency-dependence without state-dependent binding

We have previously found that the dopamine uptake inhibitor 1-(2-[bis(4-fluorophenyl)methoxy]ethyl)-4-(3-phenylpropyl)piperazine dihydrochloride (GBR 12909) inhibits neuronal sodium channels. The inhibition was profoundly dependent on the voltage protocol, suggesting that the effect is determined by the activity pattern of individual neurons. Our present study was aimed to understand more thoroughly the mechanism of this inhibition. The effect of GBR 12909 on sodium currents was investigated using whole-cell patch clamp recordings on cultured hippocampal neurons. Repetitive trains of depolarizations revealed two distinct components of inhibition: a frequency-dependent, transient and a frequency-independent, sustained component. Frequency-dependent inhibition can reflect dynamic equilibrium of binding or gating. In order to decide which is the dominant mechanism in the case of GBR 12909, we studied the rates of association and dissociation. We found an unexpectedly fast rate of association (tau=819.2 ms) to resting ion channels kept at hyperpolarized membrane potential (-150 mV), while the rate of dissociation was too slow to explain recovery between trains of stimulation (tau=248 s). These data suggest that frequency-dependent inhibition cannot be explained by binding and unbinding, but rather it is due to conformational transitions of the liganded channel, which can only be explained if ligand binding is assumed to enhance slow inactivation. We studied, therefore, the rate of slow inactivation in the presence of different concentrations of GBR 12909. We have found that GBR 12909 accelerates slow inactivation substantially (time constants more than hundredfold lower at concentrations above 10 microM), causing the time range of slow inactivation to overlap with the time range of fast inactivation. Slow inactivation can even be the dominant process, especially during subthreshold depolarizations in the presence of >10 microM of GBR 12909. This mechanism of inhibition could provide a selective inhibition of neurons not only with high frequency bursting activity but also with moderately depolarized membrane potential.

Differential effect of nicotinic agonists on the [3H]norepinephrine release from rat hippocampal slices

The aim of this study was to investigate the mechanisms involved in the effect of nicotinic agonists on the [3H]norepinephrine ([3H]NE) release from rat hippocampal slices. The stimulatory effect of nicotine, cytisine, epibatidine and anatoxin-A was completely blocked by the nicotinic antagonist mecamylamine (10 microM). In contrast, the effect of dimethylphenylpiperazinium (DMPP) was only partially inhibited by mecamylamine but was completely blocked by the NE uptake inhibitor desipramine (DMI, 10 microM). Finally, the effect of lobeline was not affected by mecamylamine and was only partially blocked by DMI. Our data indicate that the majority of nicotinic agonists increase the release of [3H]NE exclusively via stimulation of nicotinic acetylcholine receptors (nAChRs). DMPP, in addition to the stimulation of nAChRs, also evokes a carrier-mediated release. Lobeline has no stimulatory effect on nAChRs, induces a carrier-mediated release and has a further action of unidentified mechanism. Our results suggest that special caution is required for the interpretation of data, when DMPP or lobeline are used as nicotinic agonists.

Choline and acetylcholine have similar kinetic properties of activation and desensitization on the alpha7 nicotinic receptors in rat hippocampal neurons

The alpha7-type nicotinic acetylcholine receptor (nAChR) was recently found to be both fully activated and desensitized by choline, in addition to ACh. In order to understand the combined effects of the two agonists on alpha7 nAChR-mediated neuronal signaling, the kinetics of the receptor-channel's interaction with ACh and choline was examined. To this end, whole-cell and single-channel currents evoked by fast-switching pulses of the agonists were recorded in rat hippocampal neurons in culture. Currents evoked by equieffective concentrations of choline and ACh were very similar, except that choline-evoked currents decayed more quickly to the baseline after removal of the agonist, and that recovery from desensitization was faster with choline. The conductance of channels activated by choline and ACh was 91.5+/-8.5 and 82.9+/-11.6 pS, respectively. The mean apparent channel open times were close to 100 micros, with both agonists. After a 4-s exposure to concentrations up to 80 microM ACh or 600 microM choline, the extent of desensitization and the cumulative charge flow carried by the channels increased in the same proportion, until reaching a maximum. At higher concentrations of either agonist, the cumulative charge started decreasing with concentration, reflecting further desensitization. Kinetic modeling suggested that alpha7 nAChRs have at least two non-equivalent paths to desensitized states, and that choline dissociates faster than ACh from the receptor. Our results established that the main difference between choline and ACh is of affinity, and support the concept that the switching of endogenous agonist may change the desensitization-resensitization dynamics of alpha7 nAChRs.

Ca(2+)-sensitive inhibition by Pb(2+) of alpha7-containing nicotinic acetylcholine receptors in hippocampal neurons

In the present study the patch-clamp technique was applied to cultured hippocampal neurons to determine the kinetics as well as the agonist concentration- and Ca(2+)-dependence of Pb(2+)-induced inhibition of alpha7 nicotinic receptors (nAChRs). Evidence is provided that more than two-thirds of the inhibition by Pb(2+) (3-30 microM) of alpha7 nAChR-mediated whole-cell currents (referred to as type IA currents) develops rapidly and is fully reversible upon washing. The estimated values for tau(onset) and tau(recovery) were 165 and 240 ms, respectively. The magnitude of the effect of Pb(2+) was the same regardless of whether acetylcholine or choline was the agonist. Pre-exposure of the neurons for 800 ms to Pb(2+) (30 microM) decreased the amplitude and accelerated the decay phase of currents evoked by moderate to high agonist concentrations. In contrast, only the amplitude of currents evoked by low agonist concentrations was reduced when the neurons were exposed simultaneously to Pb(2+) and the agonists. Taken together with the findings that Pb(2+) reduces the frequency of opening and the mean open time of alpha7 nAChR channels, these data suggest that Pb(2+) accelerates the rate of receptor desensitization. An additional reduction of type IA current amplitudes occurred after 2-min exposure of the neurons to Pb(2+). This effect was not reversible upon washing of the neurons and was most likely due to an intracellular action of Pb(2+). Pb(2+)-induced inhibition of alpha7 nAChRs, which was hindered by the enhancement of extracellular Ca(2+) concentrations, may contribute to the neurotoxicity of the heavy metal.

Neuronal nicotinic receptors in synaptic functions in humans and rats: physiological and clinical relevance

The present report describes the participation of nicotinic receptors (nAChRs) in controlling the excitability of local neuronal circuitries in the rat hippocampus and in the human cerebral cortex. The patch-clamp technique was used to record responses triggered by the non-selective agonist ACh and the alpha7-nAChR-selective agonist choline in interneurons of human cerebral cortical and rat hippocampal slices. Evidence is provided that functional alpha7- and alpha4beta2-like nAChRs are present on somatodendritic and/or preterminal/terminal regions of interneurons in the CA1 field of the rat hippocampus and in the human cerebral cortex and that activation of the different nAChR subtypes present in the preterminal/terminal areas of the interneurons triggers the tetrodotoxin-sensitive release of GABA. Modulation by nAChRs of GABAergic transmission, which can result either in inhibition or disinhibition of pyramidal neurons, depends both on the receptor subtype present in the interneurons and on the agonist acting upon these receptors. Not only do alpha7 nAChRs desensitize faster than alpha4beta2 nAChRs, but also alpha7 nAChR desensitization induced by ACh lasts longer than that induced by choline. These mechanisms, which appear to be retained across species, might explain the involvement of nAChRs in cognitive functions and in such neurological disorders as Alzheimer's disease and schizophrenia.

Prevention of B220+ T cell expansion and prolongation of lifespan induced by Lactobacillus casei in MRL/lpr mice

We examined the therapeutic effect of heat-killed Lactobacillus casei (LC) on MRL/lpr mice. Ingestion of a diet containing 0.05% (w/w) LC from the weaning period prolonged the lifespan and tended to reduce the proportion of B220+ T cells in the spleen and mesenteric lymph nodes (MLN) of MRL/lpr mice. When LC was intraperitoneally injected once a week after the age of 8 weeks, I-A- macrophages accumulated in the spleen as well as the peritoneum and macrophage progenitors increased in the bone marrow. Moreover, the amount of IL-6 mRNA in peritoneal macrophages was reduced by LC injection. Splenocytes from LC-injected MRL/lpr mice exhibited lower proliferative responses to mitogens than those from control MRL/lpr mice and the increase in number of B220+ T cells in the spleen and MLN was prevented by LC injection. However, LC injection affected neither expression of interferon-gamma (IFN-gamma) and IL-4 mRNAs nor proliferative capacities of splenic T cells. Our findings demonstrate that LC injection accelerates macrophage recruitment and prevents the expansion of B220+ T cells without affecting the functions of T cells in MRL/lpr mice. These immunological modulations induced by LC may lead to prolongation of the lifespan of MRL/lpr mice.

[Model of abutment screw fixation for single tooth implantation]

An experimental model was constructed to test the abutment screw fixation for two Hungarian implant systems. First, abutments were tightened to 22.4 Ncm and after 4.25 hour loosening torques varied between 13.8-20.9 Ncm. Secondly, premolar-form crowns were casted and cemented on abutment-implant assemblies and cyclic load between 20-60 N was applied. 3.8-18.3 Ncm of loosening torques were measured. Four abutments of nine test assemblies were completely loosened and the cement fixation of one crown was destroyed. It was concluded that the test procedure and the model of crown-abutment-implant assemblies had given a reproducible technique to record changes in torques during a dynamic load.

Survival of a probiotic, Lactobacillus casei strain Shirota, in the gastrointestinal tract: selective isolation from faeces and identification using monoclonal antibodies

Lactobacillus casei strain Shirota (LCS) is a probiotic bacterium used in the production of fermented milk products and lactic acid bacteria preparations. To investigate the survival of LCS in the gastrointestinal tract, we have developed a selective medium and specific monoclonal antibodies to isolate and identify this strain. Selective LLV agar medium was prepared by modifying LBS medium, a selective medium for lactobacilli, through the replacement of glucose with lactitol as a carbon source and vancomycin as a selective antibiotic. Culture in LLV agar medium followed by ELISA using monoclonal antibodies specific for LCS was able to detect the organism in faeces. Using this method, we studied the faecal recovery of LCS in individuals who drank 125 ml of fermented milk which contained 10(10) live LCS for 3 days. The mean recovery was about 10(7) live bacteria per gram of faeces, indicating that LCS survived transit through the gastrointestinal tract after ingestion of the fermented milk.

Non-NMDA receptor-mediated modulation of voltage-activated outward currents in chick neurones

The effect of kainate on the voltage-activated current of cultured embryonic chick telencephalic neurones was studied by whole-cell voltage clamp recording. In addition to opening non-NMDA receptor coupled ion channels, kainate produced additional effects, with a slower time course: it modulated voltage-activated currents. These effects were blocked by the non-NMDA receptor antagonists CNQX (6-cyano-7-nitroquinoxaline-2,3-dione) and GYKI 53784 ((-)-1-(4-aminophenyl)-3- methylcarbamoyl-4-methyl-7,8-methylenedioxy-3,4- dihydro-5H-2,3-benzodiazepine), indicating that non NMDA receptors are involved. It has been shown that the reversible inhibition of outward potassium currents was partly due to a decrease of current amplitude and partly to a marked shift of the inactivation curve towards more negative potentials.

Kainate-induced inhibition of voltage-activated potassium currents in cultured chick telencephalic neurons

Kainate indirectly produces an inhibition of voltage-activated outward potassium currents on cultured chick telencephalic neurons, besides directly evoking activation of AMPA/kainate receptors (current with linear I-V curve, reversal potential near 0 mV). The former effect is also mediated by AMPA/kainate receptors. The role of [Ca2+]i in the inhibition was investigated by whole cell- and nystatin-perforated patch-clamp technique. Elevation of [Ca2+]i evoked by the Ca2+ ionophores ionomycin and A23187 caused an inhibition of outward currents as well. When the elevation of [Ca2+]i is prevented, the inhibition is decreased. These results suggest that [Ca2+]i elevation may be involved in the process.

Intracellular Ca2+ imaging of cultured chicken telencephalic cells: characterization of ionotropic glutamate receptor activation

In the present study we investigated the intracellular [Ca2+] increasing effect of the excitatory amino acid agonists kainate, AMPA and NMDA on fura-2/AM loaded chicken telencephalic cells in various conditions. Kainate (110 microM) increased [Ca2+]i to 256 +/- 23% of the basal level (n = 7). In Ca(2+)-free medium the effect of kainate on intracellular Ca2+ was completely abolished indicating that the primary source of the Ca2+ signal was the extracellular pool. Voltage dependent Ca2+ channel antagonism by Cd2+ decreased the intracellular Ca2+ elevation caused by 100 microM kainate indicating the involvement of voltage dependent Ca2+ channels (VDCC).

Subtype-specificity of the presynaptic alpha 2-adrenoceptors modulating hippocampal norepinephrine release in rat

In vivo brain microdialysis and high-performance liquid chromatography with electrochemical detection were used to study the effect of different selective alpha 2-antagonists on hippocampal norepinephrine (NE) release in freely moving awake rat. Systemic administration (0.5 mg/kg i.p.) of either the alpha 2AD-antagonist BRL 44408 or the alpha 2BC-antagonist ARC 239 did not significantly change the basal release of NE. At a higher dose (5 mg/kg i.p.) ARC 239 was still ineffective, whereas BRL 4408 caused a significant increase of the extracellular level of NF. Similar results were obtained from in vitro perfusion experiments. Rat hippocampal slices were loaded with [3H]NE and the electrical stimulation-evoked release of [3H]NE was determined. The alpha 2-antagonists were applied in a concentration range of 10(-8) to 10(-6) M, ARC 239 was ineffective, whereas BRL 44408 significantly increased the electrically induced release of [3H]NE. In agreement with the data of microdialysis and perfusion experiments, BRL 44408 displaced [3H]yohimbine from hippocampal and cortical membranes of rat brain with high affinity whereas ARC 239 was less effective. The pKi values of eight different alpha 2-adrenergic compounds showed a very good correlation (r = 0.98, slope = 1.11 P < 0.0001) in hippocampus and frontal cortex have the alpha 2-adrenoceptors have been characterized as alpha 2d-subtype. Our data indicate that hippocampal NE release in rat is regulated by alpha 2D-adrenoceptors, a species variation of the human alpha 2A-subtype.

Measurement of staphylokinase by enzyme-linked immunosorbent assay using monoclonal antibodies

Hybridoma clones producing monoclonal antibodies specific for staphylokinase were isolated. A competitive assay revealed that the monoclonal antibodies studied could be divided into at least two groups. Representatives of these groups, AS22 and B3E6, recognized quite different epitopes on staphylokinase. This finding led us to develop an assay system for the quantitative analysis of staphylokinase by enzyme-linked immunosorbent assay using AS22 as the capturing antibody and biotinylated B3E6 as the "detector". The lower limit of sensitivity of the assay was 20 pg of staphylokinase per ml. The assay exhibited good reproducibility, with values of 5.8 and 3.8% for the intra- and inter-assay coefficients of variation, respectively. Staphylokinase could be assayed in the presence of human plasma when the plasma was diluted more than 320-fold, and the measurement was unaffected by the presence of physiological concentrations of human plasminogen. Hence, this assay was considered useful for the detection and quantification of staphylokinase in clinical samples.

Differential changes in presynaptic modulation of transmitter release during aging

The purpose of this study was to assess the functional role of presynaptic alpha 2-autoreceptors in noradrenergic transmission in the hippocampus and dopamine-2 heteroreceptors in cholinergic transmission in the striatum in young, adult, and senescent rats. Male and female Wistar rats (4, 12, and 24 months old) were used and the release of radioactivity from striatal and hippocampal slices that had been loaded either with [3H]choline or with [3H]norepinephrine was measured at rest and in response to field stimulation (2 Hz, 360 shocks). The release was challenged by sulpiride, a selective dopamine-2 receptor antagonist, and CH-38083, a selective alpha 2-adrenoceptor antagonist. The dissociation constant and the number of alpha 2-adrenoceptors was also determined by binding studies using [3H]yohimbine as ligand in crude membrane preparations of frontal cortex. There were an age-related changes in alpha 2-adrenoceptor-mediated negative feedback modulation of norepinephrine release and in the density and dissociation constant of alpha 2-adrenoceptors. They were reduced in senescent rats. In contrast the presynaptic modulation of striatal cholinergic transmission by dopamine-2 receptors was not altered during aging, but the storage capacity of and the release of acetylcholine from cholinergic interneurons was significantly lower.

Evidence that GYKI 52466, a novel non-NMDA antagonist enhances the decay of kainate-induced current in cultured chicken cortical neurons

The effect of a novel non-competitive non-NMDA glutamate receptor antagonist, GYKI 52466 was studied on the glutamate agonist-induced currents in one month old cultured embryonal chicken brain neurons by a whole cell patch-clamp technique. AMPA, applied in different concentrations (30-1000 microM) did not evoke any current. Kainate evoked an increase of steady-state current (KA-current). NMDA induced a current with 5-10 times higher peak amplitude than KA, but GYKI 52466 failed to affect this current. It reduced the amplitude of KA-current in a concentration-dependent (1-100 microM) manner, and produced a slow decay of it. The IC50 value of GYKI 52466 against 100 microM KA was 20.4 +/- 6.4 microM with a Hill coefficient of 1.12. The inhibition of KA-currents was voltage-dependent with greater inhibition between -110 to -40 mV than between -30 and +60 mV. In order to compare the effect of GYKI 52466 with a well-known competitive non-NMDA antagonist, we also studied the effect of the quinoxalinedione CNQX. When GYKI 52466 and CNQX were applied together there was only a small additive effect. Our results with GYKI 52466 on glutamate agonist-induced currents in embryonic chicken cortical neurons are similar to those observed in rat hippocampal neurons.

Release of acetylcholine and noradrenaline from the cholinergic and adrenergic afferents in rat hippocampal CA1, CA3 and dentate gyrus regions

An attempt was made to study the release of acetylcholine (ACh) and noradrenaline and their presynaptic modulation in isolated slice preparations dissected from different subfields of the hippocampus: CA1, CA3 and the dentate gyrus. The slices were perfused and loaded with [3H]choline or with [3H]noradrenaline. The release in response to field stimulation was determined radiochemically and the content of transmitters was assayed by a chemiluminescent method or by HPLC combined with electrochemical detection. After 30 min of loading with [3H]choline there were marked subregional differences in the specific activity of [3H]ACh content. The highest concentration was measured in the dentate gyrus and the lowest in CA3. Evidence was obtained that in all three subfields the cholinergic axon terminals are equipped with inhibitory muscarinic autoreceptors and the noradrenergic terminals with alpha 2-autoreceptors, as indicated by an increase in transmitter release when the tissue was exposed to selective muscarinic or alpha 2-adrenoceptor antagonists. In contrast, the cholinergic boutons are not equipped with alpha 2-adrenoceptors, and noradrenergic terminals do not possess inhibitory muscarinic receptors. It is therefore concluded that while the release of both ACh and noradrenaline is controlled by negative feedback modulation, there is no possibility of establishing a presynaptic inhibitory interaction between the two.