Application of ventricular tachyarrhythmia definitions of the updated Lambeth Conventions provides incompatibility with earlier results, masks antifibrillatory activity and reduces inter-observer agreement

The Lambeth Conventions (LC I), a landmark guidance document for arrhythmia research was updated and arrhythmia definitions were changed in the new Lambeth Conventions II (LC II). This study examined whether the arrhythmia definitions of LC I and LC II yield the same qualitative results and whether LC II improves inter-observer agreement. Two independent investigators performed blinded arrhythmia analysis of the electrocardiograms of isolated, Langendorff rat hearts subjected to regional ischemia and perfused with Class I antiarrhythmics with 3 or 5 mM K⁺ in the perfusate. Data obtained with arrhythmia definitions of LC I and LC II were compared within and between observers. Applying ventricular fibrillation (VF) definition of LC II significantly increased VF incidence and reduced VF onset time irrespective of treatment by detecting 'de novo' VF episodes not found by LC I. LC II reduced the number of ventricular tachycardia (VT) episodes and simultaneously increased the number of VF episodes as compared with the respective values obtained according to LC I. Using VF definition of LC II masked the significant antifibrillatory effects of flecainide and the high K⁺ concentration identified with the VF definition of LC I. When VF incidence was tested, a very strong inter-observer agreement was found according to LC I, whereas using VF definition of LC II reduced inter-observer agreement. It is concluded that LC II shifts some tachyarrhythmias from VT to VF class, and thus results obtained by arrhythmia definitions of LC I and LC II are not compatible; VF definition of LC II may change the conclusion of pharmacological, physiological and pathophysiological arrhythmia investigations and may reduce inter-observer agreement. Thus, VT and VF definitions of LC II should be amended in order to increase compatibility and inter-observer agreement.

Hyperventilation assists proarrhythmia development during delayed repolarization in clofilium-treated, anaesthetized, mechanically ventilated rabbits

Hyperventilation reduces partial pressure of CO₂ (PCO₂) in the blood, which results in hypokalaemia. Hypokalaemia helps the development of the life-threatening torsades de pointes type ventricular arrhythmia (TdP) evoked by repolarization delaying drugs. This implies that hyperventilation may assist the development of proarrhythmic events. Therefore, this study experimentally investigated the effect of hyperventilation on proarrhythmia development during delayed repolarization. Phenylephrine (an α₁-adrenoceptor agonist) and clofilium (as a representative repolarization delaying agent inhibiting the rapid component of the delayed rectifier potassium current, I_Kr) were administered intravenously to pentobarbital-anaesthetized, mechanically ventilated, open chest rabbits. ECG was recorded, and the onset times and incidences of the arrhythmias were determined. Serum K⁺, pH and PCO₂ were measured in arterial blood samples. Clofilium prolonged the rate corrected QT interval. TdP occurred in 15 animals (TdP+ group), and did not occur in 14 animals (TdP- group). We found a strong, positive, linear correlation between serum K⁺ and PCO₂. There was no relationship between the occurrence of TdP and the baseline K⁺ and PCO₂ values. However, a positive, linear correlation was found between the onset time of the first arrhythmias and the K⁺ and PCO₂ values. The regression lines describing the relationship between PCO₂ and onset time of first arrhythmias were parallel in the TdP+ and TdP- groups, but the same PCO₂ resulted in earlier arrhythmia onset in the TdP+ group than in the TdP- group. We conclude that hyperventilation and hypocapnia with the resultant hypokalaemia assist the multifactorial process of proarrhythmia development during delayed repolarization. This implies that PCO₂ and serum K⁺ should be controlled tightly during mechanical ventilation in experimental investigations and clinical settings when repolarization-delaying drugs are applied.

Heats of Adsorption and Reaction of CO on Iron/Manganese Oxide Catalysts

The heats of adsorption and reaction of CO have been measured on reduced Fe/Mn oxide catalysts of different compositions at temperatures between 263 and 543 K. The heats of adsorption depend only to a small extent on the manganese content of the catalyst and are independent of the temperature of reduction. The former fact points to a more structural than electronic effect of the manganese oxide addition. The heats of adsorption are, however, strongly dependent on measurement temperature, increasing from about 60 kJ mol-1 at 263 K to about 200 kJ mol-1 at 493 K and then decreasing again to about 180 kJ mol-1 at 543 K. This temperature dependence can be explained by consecutive reactions following CO adsorption, i.e. the Boudouard reaction, dissociation of CO and diffusion of carbon into the bulk of iron. The amount of CO adsorbed is correlated to the metallic iron content in the surfaces of the catalysts.

Classification and characterization of a laboratory chicken rotavirus strain carrying G7P[35] neutralization antigens on the genotype 4 backbone gene configuration

The laboratory rotavirus strain, BRS/115, has been used for more than two decades to monitor rotaviruses in specific pathogen free flocks of laying hens. However, the virus strain has not been characterized in detail. Therefore we aimed at the description of molecular features of BRS115 by using random primed reverse transcription-PCR of the genomic RNA followed by massive parallel sequencing using the semiconductor sequencing technology. Over 64,000 trimmed reads mapped to reference sequences obtained from GenBank. The strain classified into the species Rotavirus A and genotyped G7-P[35]-I4-R4-C4-M4-A16-N4-T4-E11-H4 according to guidelines of the Rotavirus Classification Working Group. Phylogenetic analysis identified shared features with chicken, turkey and pigeon origin rotaviruses. This study demonstrates the robustness of next generation sequencing in the characterization of reference virus materials used in specialized laboratories.

Rotavirus strains in neglected animal species including lambs, goats and camelids

Surveillance of rotavirus infections and circulating strains in small ruminants (i.e. lambs, goats and camelids) has been a neglected research area in the past. However, recent years that have seen an intensification of surveillance in humans and livestock animals, where vaccines to reduce disease burden caused by Rotavirus A (RVA) are available, led to the efforts to better understand the epidemiology, ecology and evolution of RVA strains in other hosts, including lambs, goats and camelids. The aim of this review is to provide an update of the epidemiology and strain diversity of RV strains in these species through searching for relevant information in public data bases.

One year survey of human rotavirus strains suggests the emergence of genotype G12 in Cameroon

In this study the emergence of rotavirus A genotype G12 in children <5 years of age is reported from Cameroon during 2010/2011. A total of 135 human stool samples were P and G genotyped by reverse transcriptase PCR. Six different rotavirus VP7 genotypes were detected, including G1, G2, G3, G8, G9, and G12 in combinations with P[4], P[6] and P[8] VP4 genotypes. Genotype G12 predominated in combination with P[8] (54.1%) and P[6] (10.4%) genotypes followed by G1P[6] (8.2%), G3P[6] (6.7%), G2P[4] (5.9%), G8P[6] (3.7%), G2P[6] (0.7%), G3P[8] (0.7%), and G9P[8] (0.7%). Genotype P[6] strains in combination with various G-types represented a substantial proportion (N=44, 32.6%) of the genotyped strains. Partially typed strains included G12P[NT] (2.2%); G3P[NT] (0.7%); G(NT)P[6] (1.5%); and G(NT)P[8] (0.7%). Mixed infections were found in five specimens (3.7%) in several combinations including G1+ G12P[6], G2+ G3P[6] + P[8], G3+ G8P[6], G3 + G12P[6] + P[8], and G12P[6] +P[8]. The approximately 10% relative frequency of G12P[6] strains detected in this study suggests that this strain is emerging in Cameroon and should be monitored carefully as rotavirus vaccine is implemented in this country, as it shares neither G- nor P-type specificity with strains in the RotaTeq® and Rotarix® vaccines. These findings are consistent with other recent reports of the global spread and increasing epidemiologic importance of G12 and P[6] strains.

Global distribution of group A rotavirus strains in horses: a systematic review

Group A rotavirus (RVA) is a major cause of diarrhea and diarrhea-related mortality in foals in parts of the world. In addition to careful horse farm management, vaccination is the only known alternative to reduce the RVA associated disease burden on horse farms. The precise evaluation of vaccine effectiveness against circulating strains needs enhanced surveillance of equine RVAs in areas where vaccine is already available or vaccine introduction is anticipated. Therefore, we undertook the overview of relevant information on epidemiology of equine RVA strains through systematic search of public literature databases. Our findings indicated that over 99% of equine RVA strains characterized during the past three decades belonged to two common genotypes, G3P[12] and G14P[12], whereas most of the minority equine RVA strains were probably introduced from a heterologous host by interspecies transmission. These baseline data on RVA strains in horses shall contribute to a better understanding of the spatiotemporal dynamics of strain prevalence in vaccinated and non-vaccinated herds.

Zoonotic transmission of reassortant porcine G4P[6] rotaviruses in Hungarian pediatric patients identified sporadically over a 15 year period

Genotype G4P[6] Rotavirus A (RVA) strains collected from children admitted to hospital with gastroenteritis over a 15 year period in the pre rotavirus vaccine era in Hungary were characterized in this study. Whole genome sequencing and phylogenetic analysis was performed on eight G4P[6] RVA strains. All these RVA strains shared a fairly conservative genomic configuration (G4-P[6]-I1/I5-R1-C1-M1-A1/A8-N1-T1/T7-E1-H1) and showed striking similarities to porcine and porcine-derived human RVA strains collected worldwide, although genetic relatedness to some common human RVA strains was also seen. The resolution of phylogenetic relationship between porcine and human RVA genes was occasionally low, making the evaluation of host species origin of individual genes sometimes difficult. Yet the whole genome constellations and overall phylogenetic analyses indicated that these eight Hungarian G4P[6] RVA strains may have originated by independent zoonotic transmission, probably from pigs. Future surveillance studies of human and animal RVA should go parallel to enable the distinction between direct interspecies transmission events and those that are coupled with reassortment of cognate genes.

Review of group A rotavirus strains reported in swine and cattle

Group A rotavirus (RVA) infections cause severe economic losses in intensively reared livestock animals, particularly in herds of swine and cattle. RVA strains are antigenically heterogeneous, and are classified in multiple G and P types defined by the two outer capsid proteins, VP7 and VP4, respectively. This study summarizes published literature on the genetic and antigenic diversity of porcine and bovine RVA strains published over the last 3 decades. The single most prevalent genotype combination among porcine RVA strains was G5P[7], whereas the predominant genotype combination among bovine RVA strains was G6P[5], although spatiotemporal differences in RVA strain distribution were observed. These data provide important baseline data on epidemiologically important RVA strains in swine and cattle and may guide the development of more effective vaccines for veterinary use.

Shared G12 VP7 gene among human and bovine rotaviruses detected in Cameroonian villages

Group A rotaviruses (RVA) are an important enteric pathogen in humans and livestock animals. Transmission of animal RVA strains to humans has been documented on several occasions. A reverse route of transmission of RVA under natural circumstances is anticipated, although evidence is scarce. However, experimental studies indicated that animals can be infected with human RVAs. By screening the stool samples collected from 157 cattle during 2011 in two Cameroonian villages, four samples (2.5%) were found positive for RVA. Upon sequence analysis of a 410 bp fragment of the VP7 gene, the RVA strains shared up to 100% nt identity to each other and to G12 RVAs identified in human patients living in the same geographic regions. This finding provides evidence for a human-to-animal transmission of an epidemic human rotavirus strain.

Novel NSP4 genotype in a camel G10P[15] rotavirus strain

In this study a Kuwaiti camel rotavirus strain, RVA/Camel-wt/KUW/s21/2010/G10P[15], is characterized by sequencing and phylogenetic analysis. The strain had multiple genes with high nucleotide sequence similarities to ovine and bovine strains (VP2, ≤ 96%; NSP2 and NSP5, ≤ 97%, NSP3, ≤ 94%), or, to porcine strains (VP1, ≤ 89%). Other genes had moderate sequence similarities (VP4, ≤ 87%; VP6, ≤ 81%; VP7, ≤ 82%) with reference strains from ruminants. The NSP4 gene shared limited sequence identity (≤ 71%) with other mammalian and avian rotavirus NSP4 types, and was designated a novel genotype, E15. This study demonstrates genetic diversity in the outer capsid and some backbone genes of an old-world camelid rotavirus strain and uncovers its common evolutionary roots with strains from other ruminants.

Detection of rare reassortant G5P[6] rotavirus, Bulgaria

During the ongoing rotavirus strain surveillance program conducted in Bulgaria, an unusual human rotavirus A (RVA) strain, RVA/Human/BG/BG620/2008/G5P[6], was identified among 2200 genotyped Bulgarian RVAs. This strain showed the following genomic configuration: G5-P[6]-I1-R1-C1-M1-A8-N1-T1-E1-H1. Phylogenetic analysis of the genes encoding the neutralization proteins and backbone genes identified a probable mixture of RVA genes of human and porcine origin. The VP1, VP6 and NSP2 genes were more closely related to typical human rotavirus strains. The remaining eight genes were either closely related to typical porcine and unusual human-porcine reassortant rotavirus strains or were equally distant from reference human and porcine strains. This study is the first to report an unusual rotavirus isolate with G5P[6] genotype in Europe which has most likely emerged from zoonotic transmission. The absence of porcine rotavirus sequence data from this area did not permit to assess if the suspected ancestral zoonotic porcine strain already had human rotavirus genes in its genome when transmitted from pig to human, or, the transmission was coupled or followed by gene reassortment event(s). Because our strain shared no neutralization antigens with rotavirus vaccines used for routine immunization in children, attention is needed to monitor if this G-P combination will be able to emerge in human populations. A better understanding of the ecology of rotavirus zoonoses requires simultaneous monitoring of rotavirus strains in humans and animals.

Surveillance of human rotaviruses in 2007-2011, Hungary: exploring the genetic relatedness between vaccine and field strains

BACKGROUND

The availability of rotavirus vaccines has resulted in an intensification of post vaccine strain surveillance efforts worldwide to gain information on the impact of vaccines on prevalence of circulating rotavirus strains.

OBJECTIVES

In this study, the distribution of human rotavirus G and P types in Hungary is reported. In addition, the VP4 and VP7 genes of G1P[8] strains were sequenced to monitor if vaccine-derived strains were introduced and/or some strains/lineages were selected against.

STUDY DESIGN

The study was conducted in 8 geographic areas of Hungary between 2007 and 2011. Rotavirus positive stool samples were collected from diarrheic patients mostly <5 years of age. Viral RNA was amplified by multiplex genotyping RT-PCR assay, targeting the medically most important G and P types. When needed, sequencing of the VP7 and VP4 genes was performed.

RESULTS

In total, 2380 strains were genotyped. During the 5-year surveillance we observed the dominating prevalence of genotype G1P[8] (44.87%) strains, followed by G4P[8] (23.4%), G2P[4] (14.75%) and G9P[8] (6.81%) genotypes. Uncommon strains were identified in a low percentage of samples (4.12%). Phylogenetic analysis of 318 G1P[8] strains identified 55 strains similar to the Rotarix strain (nt sequence identities; VP7, up to 97.9%; VP4, up to 98.5%) although their vaccine origin was unlikely.

CONCLUSIONS

Current vaccines would have protected against the majority of identified rotavirus genotypes. A better understanding of the potential long-term effect of vaccine use on epidemiology and evolutionary dynamics of co-circulating wild type strains requires continuous strain surveillance.

Complete molecular genome analyses of equine rotavirus A strains from different continents reveal several novel genotypes and a largely conserved genotype constellation

In this study, the complete genome sequences of seven equine group A rotavirus (RVA) strains (RVA/Horse-tc/GBR/L338/1991/G13P[18], RVA/Horse-wt/IRL/03V04954/2003/G3P[12] and RVA/Horse-wt/IRL/04V2024/2004/G14P[12] from Europe; RVA/Horse-wt/ARG/E30/1993/G3P[12], RVA/Horse-wt/ARG/E403/2006/G14P[12] and RVA/Horse-wt/ARG/E4040/2008/G14P[12] from Argentina; and RVA/Horse-wt/ZAF/EqRV-SA1/2006/G14P[12] from South Africa) were determined. Multiple novel genotypes were identified and genotype numbers were assigned by the Rotavirus Classification Working Group: R9 (VP1), C9 (VP2), N9 (NSP2), T12 (NSP3), E14 (NSP4), and H7 and H11 (NSP5). The genotype constellation of L338 was unique: G13-P[18]-I6-R9-C9-M6-A6-N9-T12-E14-H11. The six remaining equine RVA strains showed a largely conserved genotype constellation: G3/G14-P[12]-I2/I6-R2-C2-M3-A10-N2-T3-E2/E12-H7, which is highly divergent from other known non-equine RVA genotype constellations. Phylogenetic analyses revealed that the sequences of these equine RVA strains are related distantly to non-equine RVA strains, and that at least three lineages exist within equine RVA strains. A small number of reassortment events were observed. Interestingly, the three RVA strains from Argentina possessed the E12 genotype, whereas the three RVA strains from Ireland and South Africa possessed the E2 genotype. The unusual E12 genotype has until now only been described in Argentina among RVA strains collected from guanaco, cattle and horses, suggesting geographical isolation of this NSP4 genotype. This conserved genetic configuration of equine RVA strains could be useful for future vaccine development or improvement of currently used equine RVA vaccines.

Oxidation of Acetaldehyde and Propionaldehyde on a V2O5-TiO2 Catalyst

The partial oxidation of acetaldehyde and propionaldehyde on a TiO2 supported VO x catalyst in presence of water vapour was investigated in the temperature range from 120 to 280 °C. The selective oxidation to the appropriate carboxylic acids depended on the kind of aldehyde and the reaction temperature. An oxidative cleavage to lower carboxylic acids and CO x was also found. Furthermore, the kinetic model for the process of oxidation of acetaldehyde and propionaldehyde over the V2O5-TiO2 catalyst was developed.

Activation and isomerization of n-butane on sulfated zirconia model systems—an integrated study across the materials and pressure gaps

Butane activation has been studied using three types of sulfated zirconia materials, single crystalline epitaxial films, nanocrystalline films, and powders. A surface phase diagram of zirconia in interaction with SO(3) and water was established by DFT calculations, which was verified by LEED investigations on single-crystalline films and by IR spectroscopy on powders. At high sulfate surface densities a pyrosulfate species is the prevailing structure in the dehydrated state; if such species are absent, the materials are inactive. Theory and experiment show that the pyrosulfate can react with butane to give butene, H(2)O and SO(2), hence butane can be activated via oxidative dehydrogenation. This reaction occurred on all investigated materials; however, isomerization could only be proven for powders. Transient and equilibrium adsorption measurements in a wide pressure and temperature range (isobars measured via UPS on nanocrystalline films, microcalorimetry and temporal analysis of products measurements on powders) show weak and reversible interaction of butane with a majority of sites but reactive interaction with <5 micromol g(-1) sites. Consistently, the catalysts could be poisoned by adding sodium to the surface in a ratio S/Na = 35. Future research will have to clarify what distinguishes these few sites.

Abnormal Cell-Specific Expressions of Certain Protein Kinase C Isoenzymes in Peripheral Mononuclear Cells of Patients with Systemic Lupus Erythematosus: Effect of Corticosteroid Application

We have studied the expressions of various protein kinase C (PKC) isoenzymes in T cells and monocytes from patients with systemic lupus erythematosus (SLE), in comparison to those of healthy controls and patients with other immunological disorders. As measured by Western blotting, the levels of PKCbeta, delta, eta, epsilon, theta and zeta (but not of PKCalpha) significantly decreased in T cells of SLE patients. In monocytes, however, we observed marked suppressions only in the expressions of PKCdelta, epsilon and zeta but not in the expressions of other PKC isoforms. In vivo corticosteroid application, as well as in vitro steroid treatment of monocytes, elevated the expressions of most isoforms close to normal values; however, the decreased levels of PKCtheta and zeta were not affected by steroid application. These alterations were characteristic to SLE because we could not detect any changes in the PKC levels in mononuclear cells of primary Sjögren's syndrome and mixed connective tissue disease patients. These results suggest that impaired PKC isoenzyme pattern may exist in the T cells and monocytes of SLE patients. Furthermore, the clinically efficient glucocorticoid application in SLE can increase the expression of some members of PKC system.

Opposite roles of protein kinase C isoforms in proliferation, differentiation, apoptosis, and tumorigenicity of human HaCaT keratinocytes

We have previously shown that the protein kinase C (PKC) system plays a pivotal role in regulation of proliferation and differentiation of the human keratinocyte line HaCaT which is often used to assess processes of immortalization, transformation, and tumorigenesis in human skin. In this paper, using pharmacological and molecular biology approaches, we investigated the isoform-specific roles of certain PKC isoenzymes (conventional cPKCalpha and beta; novel nPKCdelta and epsilon) in the regulation of various keratinocyte functions. cPKCalpha and nPKCdelta stimulated cellular differentiation and increased susceptibility of cells to actions of inducers of apoptosis, and they markedly inhibited cellular proliferation and tumor growth in immunodeficient mice. In marked contrast, cPKCbeta and nPKCepsilon increased both in vitro and in vivo growth of cells and inhibited differentiation and apoptosis. Our data present clear evidence for the specific, antagonistic roles of certain cPKC and nPKC isoforms in regulating the above processes in human HaCaT keratinocytes.

Presenilin-1 and the amyloid precursor protein are transported bidirectionally in the sciatic nerve of adult rat

The amyloid precursor protein (APP) and presenilin-1 (PS-1) are not only of importance for the normal functioning of the various neurons, but also play central roles in the pathogenesis of Alzheimer's disease (AD). Through the use of immunohistochemical and Western blot techniques, the bidirectional axonal transport of these proteins has been demonstrated in the sciatic nerve of adult rat. Double-ligation of the sciatic nerve for 6, 12 or 24h was observed to cause a progressive accumulation of the 45kDa presenilin-1 holoprotein and APPs with molecular masses of 116 and 94kDa on both sites of the ligature. It is concluded that the functions of presenilin-1 and APPs are not restricted to the neuronal perikarya: they may carry information in both directions, from the cell body to the axon terminals and vice versa.

Presenilin-1 and its N-terminal and C-terminal fragments are transported in the sciatic nerve of rat

The axonal transport of presenilin-1 was investigated in a spinal cord-sciatic nerve-neuromuscular junction model system in the rat. The technique of unilateral sciatic nerve ligation, using double ligatures, was combined with immunohistochemical staining and Western blotting to examine the axonal transport of the protein. Immunohistochemical studies involving the use of polyclonal antibodies for either the N-terminal or the C-terminal domain of presenilin-1 furnished evidence that both fragments may be present not only in the neuronal cell bodies, but also in the motoric and sensory axons and the motoric axon terminals at the neuromuscular junctions. After double ligation of the sciatic nerve for 6, 12 or 24 h, progressive immunostaining of presenilin-1 occurred above the upper ligature and to a lesser extent below the lower ligature. Double staining of the sciatic nerve for presenilin-1 and for amyloid precursor protein revealed overlapping immunoreactivity. Western blotting confirmed the accumulation of the approximately 20-kDa C-terminal and approximately 25-kDa N-terminal fragments and the full-length 45-kDa holoprotein of presenilin-1 both above and below the ligature. It is concluded that besides the larger amounts of C-terminal and N-terminal fragments, a smaller quantity of intact presenilin-1 may be present and conveyed bidirectionally in the sciatic nerve of the rat. These results lend further support to the suggestion that presenilin-1 may leave the trans-Golgi network and be found in the axons and axon terminals of the various neurons.

Phorbol ester treatment inhibits proliferation and differentiation of cultured human skeletal muscle satellite cells by differentially acting on protein kinase C isoforms

We have previously shown that cultured human skeletal muscle cells express five protein kinase C (PKC) isoforms (PKCalpha, -gamma, -eta, -theta, and -zeta) and that expression levels of various PKC isozymes differentially change during differentiation. In this study we investigated the effects of the PKC activator phorbol 12-myristate 13-acetate (PMA) on differentiation and on PKC isozymes of human skeletal muscle satellite cells. PMA inhibited the growth and fusion of cultured human myoblasts in a dose-dependent manner. In addition, prolonged treatment of cells with PMA suppressed the expression of the myogenic differentiation marker desmin showing similar dose-response characteristics. Furthermore, PMA also induced the intracellular translocation of PKCgamma, -eta, and -theta, whereas cellular localization of PKCalpha and -zeta were not altered. These changes in subcellular localization patterns were of great importance since only those PKC isoforms were translocated that possessed alterations in their expression levels during differentiation. Our findings, therefore, suggest that the PMA-induced inhibition of differentiation of human skeletal muscle cells is mediated by certain PKC isoforms. Moreover, these data strongly argue for differential and isozyme-specific roles of various PKC isoforms in these processes.

Effects of chronic metrifonate treatment on cholinergic enzymes and the blood-brain barrier

After an acute (4 h) treatment with an irreversible cholinesterase inhibitor organophosphate, metrifonate (100 mg/kg i.p.), the activities of both acetyl- and butyrylcholinesterase were inhibited (66.0-70.7% of the control level) in the rat brain cortex and hippocampus. There were no significant changes in the acetyl- and butyrylcholinesterase activities in the olfactory bulb, or in the choline acetyltransferase activity in all three brain areas. After chronic (2 or 5 week) metrifonate treatment (100 mg/kg daily i.p.), the activities of both cholinesterases were substantially inhibited in the rat brain cortex and hippocampus (15.8-31.8% of the control levels), but there was no inhibition of the choline acetyltransferase activity. Moreover, chronic metrifonate treatment did not have any effect on the distribution of the acetylcholinesterase molecular forms. In vitro, metrifonate proved to be a more potent inhibitor of butyryl- than of acetylcholinesterase in both the cortex and the hippocampus. In the hippocampus, the butyrylcholinesterase activity was twice as sensitive to metrifonate inhibition as that in the cortex (IC50 values 0.22 and 0.46 microM, respectively). The effects of chronic (5 week) metrifonate treatment on the blood-brain barrier of the adult rat were examined. The damage to the blood-brain barrier was judged by the extravasation of Evans' blue dye in three brain regions: the cerebral cortex, the hippocampus, and the striatum. No extravasation of Evans' blue dye was found in the brain by fluorometric quantitation. These data indicate that chronic metrifonate treatment may increase the extracellular acetylcholine level via cholinesterase inhibition, but it does not have any effects on the blood-brain barrier. Therefore, it appears reasonable to hypothesize that cholinesterase activities do not play a role in the blood-brain barrier permeability.

Donepezil dose-dependently inhibits acetylcholinesterase activity in various areas and in the presynaptic cholinergic and the postsynaptic cholinoceptive enzyme-positive structures in the human and rat brain

In the symptomatic treatment of mild to moderately severe dementia associated with Alzheimer's disease, donepezil (E2020) has been introduced for the inhibition of acetylcholinesterase activity in the human brain. However, there is no morphological evidence as to how this chemical agent affects the acetylcholinesterase-positive structures in the various areas of the human and the rat CNS. This study demonstrates by histochemical means that donepezil exerts a dose-dependent inhibitory effect in vitro on acetylcholinesterase activity. The most sensitive areas were the cortex and the hippocampal formation. Within the different layers of the cortex, the cholinoceptive acetylcholinesterase-positive postsynaptic pyramidal cell bodies were more sensitive than the presynaptic cholinergic axonal processes. In the cortex, the cell body staining was already abolished by even 2 x 10(-8)M donepezil, whereas the axonal staining could be eliminated only by at least 5 x 10(-8)M donepezil. In the hippocampus, the axonal acetylcholinesterase reaction end-product was eliminated by 5 x 10(-7)M donepezil. The most resistant region was the putamen, where the staining intensity was moderately reduced by 1 x 10(-6)M donepezil. In the rat brain, the postsynaptic cholinoceptive and presynaptic cholinergic structures were inhibited by nearly the same dose of donepezil as in the human brain. These histochemical results provide the first morphological evidence that, under in vitro circumstances, donepezil is not a general acetylcholinesterase inhibitor in the CNS, but rather selectively affects the different brain areas and, within these, the cholinoceptive and cholinergic structures. The acetylcholinesterase staining in the nerve fibers (innervating the intracerebral blood vessels of the human brain and the extracerebral blood vessels of the rat brain) and at the neuromuscular junction in the diaphragm and gastrocnemius muscle of rat, was also inhibited dose dependently by donepezil. It is concluded that donepezil may be a valuable tool with which to influence both the pre- and the postsynaptic acetylcholinesterase-positive structures in the human and rat central and peripheral nervous systems.

Montmorillonites Modified with Carbonaceous Deposits

The mechanism of formation of carbonaceous deposits on montmorillonites was studied for systems prepared by sorption of polymers on pillared montmorillonites and subsequent carbonization. Temperature-programmed desorption of ammonia and X-ray photoelectron spectroscopy showed that polymer was attached to Al-OH acidic sites of smectite layers. Pillars were not influenced to a greater extent. Islands of carbonaceous material were formed, but the amount of deposited carbon depended strongly upon carbonization conditions. The hydrophylic and acidic properties of carbon-covered silica aluminas differed strongly from those of the starting material. Copyright 2000 Academic Press.

In vitro effects of metrifonate on neuronal amyloid precursor protein processing and protein kinase C level

Alteration in the processing of the amyloid precursor protein (APP) is a central event in the formation of amyloid deposits in the brains of individuals with Alzheimer's disease (AD). It has been suggested that acetylcholinesterase (AChE) inhibitors, which promote the cholinergic function and consequently improve the cognitive deficits, may also exert a neuroprotective effect by activating normal APP processing. We now report that an irreversible AChE inhibitor (metrifonate) increase the cell-associated APP level in a basal forebrain neuronal culture and also elevate the amount of APP secreted into the medium. The alterations in APP processing were accompanied by increased protein kinase C (PKC) levels. The results suggest that AChE inhibitors modulate the metabolism of APP, possibly via their stimulatory effects on PKC. Since changes in the activity and level of PKC may be involved in the pathogenesis of AD, it is concluded that the beneficial effect of metrifonate in AD therapy may be due not only to the stimulatory cholinergic function, but also to its activating effect on PKC.

Human amyloid-beta1-42 applied in vivo inhibits the fast axonal transport of proteins in the sciatic nerve of rat

Human amyloid-beta1-42 has been suggested to be a pathogenetic factor in Alzheimer's disease. The precise mechanism by which this peptide causes the degeneration of neurons in the affected brain is not yet fully understood. By using immunohistochemistry we explored the inhibitory effects of human amyloid-beta1-42 applied in vivo on the fast axonal transport of acetylcholinesterase, the amyloid precursor protein, the vesicular acetylcholine transporter and synaptophysin in the sciatic nerve of rat. Our findings provide evidence for the in vivo neurotoxic effect of human amyloid-beta peptide.