The association of C3435T single-nucleotide polymorphism, Pgp-glycoprotein gene expression levels and carbamazepine maintenance dose in patients with epilepsy

The ABCB1 gene encodes the P-glycoprotein (Pgp) protein, which is thought to transport various antiepileptic drugs. The single nucleotide polymorphism (SNP) (C3435T) in exon 26 of this gene correlates with the altered expression levels of P-glycoprotein, range of drug response and clinical conditions. In order to investigate the influence of this polymorphism on the susceptibility to and efficacy of carbamazepine therapy, we evaluated the allelic frequency and genotype distribution of this variant in 162 epilepsy patients from the Republic of Macedonia. Statistically significant differences were detected neither in the allelic frequency and genotype distribution between carbamazepine-resistant and carbamazepine-responsive epilepsy patients nor between the subgroups of carbamazepine (CBZ)-responsive patients treated with different CBZ doses. However, the T-allele was enriched in CBZ-responsive patients who required higher maintenance CBZ doses, This observation was substantiated by the findings that the median total plasma levels were the lowest in patients with CC (20 μmol/L) followed by CT (23 μmol/L) and TT (29 μmol/L) genotypes. Patients with a CC genotype also had a higher likelihood of response compared to patients with CT or TT genotypes over a wide range (400–1000 mg/day) of initial doses of CBZ. The T allele showed a reduced expression of ~5% compared to the C allele in peripheral blood mononuclear cells in heterozygotes for the variant. This difference might be translated into ~10% difference in homozygotes for the variant, which would explain the trend towards a dose-dependent efficacy of the CBZ treatment in patients with different genotypes. A larger prospective study is warranted to clarify the clinical utility of a genotypespecific individualized CBZ therapy

The role of molecular mimicry in the etiology of Guillain Barré Syndrome

Molecular mimicry between host tissue structures and microbial components has been proposed as the pathogenic mechanism for triggeringof autoimmune diseases by preceding infection. Recent studies stated that molecular mimicry as the causative mechanism remains unproven for most of the human diseases. Still, in the case of the peripheral neuropathy Guillain-Barré syndrome (GBS) this hypothesis is supported by abundant experimental evidence. GBS is the most frequent cause of acute neuromuscular paralysis and in some cases occurs after infection with Campylobacter jejuni (C. jejuni). Epidemiological studies, showed that more than one third of GBS patients had antecedent C. jejuni infection and that only specific C. jejuni serotypes are associated with development of GBS. The molecular mimicry between the human gangliosides and the core oligosaccharides of bacterial lipopolysaccharides (LPSs) presumably results in production of antiganglioside cross-reactive antibodies which are likely to be a contributory factor in the induction and pathogenesis of GBS. Antiganglioside antibodies were found in the sera from patients with GBS and by sensitization of rabbits with gangliosides and C. jejuni LPSs animal disease models of GBS were established. GBS as prototype of post-infection immune-mediated disease probably will provide the first verification that an autoimmune disease can be triggered by molecular mimicry

Association between CYP2C19*2 variant and clinical outcome in Clopidogrel treated patients from Republic of Macedonia

Clopidogrel is the thienopyridine of choice for prevention of ischemic events and stent thrombosis in patients with atherotrombotic disease. Recent studies suggest that certain genetic variants involving CYP450 system are responsible for wide interindividual variability in treatment response profiles among clopidogrel treated individuals. The aim of this study was to define the prevalence of most common CYP2C19*2: 681G>A (rs4244285) allelic variant in Macedonian population and determine the risk association with major cardiovascular adverse events in clopidogrel treated patients with atherotrombotic cardiovascular disease. CYP2C19 *2 genotype was assessed in 198 subjects from R.Macedonia. The association between the reduced function CYP2C19 *2 A allele and clinical outcome was evaluated in 67 clopidogrel treated patients within a follow up period of at least 6 months (from 6 to 60 months) after initializing clopidogrel therapy. The population frequency of polymorphic A allele responsible for impaired clopidogrel metabolism in Macedonian population was 0.18. CYP2C19*2 variant was significantly associated with increased rate of adverse cardiovascular events in the allelic (OR= 3.188; 95% CI= 1.437-7.058), dominant (OR=3.477; 95% CI= 1.256-9.630) and co-dominant model ( OR=6.750, 95% CI: 1.186-38.410) of statistical analysis (adjusted OR= 2.619; Ptrend=0.0088). The influence of CYP2C19*2 was most strongly correlated with worse event free survival in patients carrying AA genotype (log rank P = 0.0024) and patients carrying at least one CYP2C19*2 reduced function allele (log rank P=0.0058). CYP2C19*2 genetic variant in the population from Republic of Macedonia has similar distribution as determined in other European populations. Carriage of reduced function CYP2C19 *2 allele is associated with worse event free survival in clopidogrel treated patients with atherotrombotic disorders

Design, synthesis and determination of physical and chemical characteristics of glycoconjugates as model for oligosaccharide vaccines against vibrio cholerae

Cholera is toxin-mediated enteroinfection, with epidemic character and there are approximately 120000 death cases per year worldwide. Protection against cholera has not been accomplished due to deficiencies in the licensed vaccines. Serum vibriocidal activity mediated by LPS antibodies is the only immune segment correlated with the resistance of cholera. On the basis of literature data (Robbins JB, 1990; Ogawa Y, 1996) we synthesized glucoconjugates, composed of detoxified LPS from Vibrio cholerae and protein carriers. Conjugate vaccines were prepared by binding acetic acid and hydrazine-treated lipopolysaccharide (LPS) from Vibrio cholerae O1, serotype Inaba, to cholera toxin B-subunit (CT-B) and bovine serum albumin (cBSA). Adipic acid dihydrazide was used for derivatization of oligosaccharides and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) as conjugating agent. SDS-PAGE, glycoprotein detection and TLC dot-blot were used for physical and chemical analysis of the prepared four types of conjugates. Safe level of endotoxins, measured by LAL assay was detected in all conjugates. The synthesized conjugates can be used for monitoring immunization schemes on experimental animals. It is to be expected that conjugated vaccines are safe and efficient and that will have high immunogenic and T-dependant characteristics with long immune protection against cholera

Ionotropic Glutamate Receptors (iGluRs): Overview of iGluR2 ligand binding domain in complex with agonists and antagonists

Ionotropic glutamate receptors (iGluRs) constitute a family of ligand gated ion channels subdivided in three classes, NMDA, AMPA (iGluA1-4) and KA (1-5) according to the agonists that selectively activate them. iGluRs are tetrameric assemblies of highly homologous receptor subunits. They are critically important for normal brain function and are considered to be involved on neurological disorders and degenerative diseases such as schizophrenia, Alzheimer’s disease, brain damage following stroke and epilepsy. Since the first publication of the structure of recombinant soluble protein of ligand binding domain of GluA2 extensive studies on this group of receptors were performed and many crystal structures as complexes of GluA2-LBD with agonists, partial agonists and antagonists were obtained. The structural information in combination with functional data makes good platform for consecutive investigation and design of new selective drugs which will be used in treatment of neurodegerative diseases

Glycoconjugates as target antigens in peripheral neuropathies

Identification and characterization of antigens present at the human peripheral nerve is a great challenge in the field of neuroimmunology. The latest investigations are focused on the understanding of the biology of glycoconjugates present at the peripheral nerve, and their immunological reactivity. Increased titers of antibodies that recognize carbohydrate determinants of glycoconjugates (glycolipids and glycoproteins) are associated with distinct neuropathic syndromes. There is considerable cross-reactivity among anti-ganglioside antibodies, resulting from shared oligosaccharide epitopes, possibly explaining the overlap in syndromes observed in many affected patients. Sera from patients with neuropathies (GBS, chronic inflammatory demielynating polyneuropathy - CIDP, multifocal motor neuropathy - MMN), cross-react with glycoproteins isolated from human peripheral nerve and from Campylobacter jejuni O:19. The frequency of occurrence of antibodies against these glycoproteins is different, depending of the type of neuropathy. Identification of the cross-reactive glycoproteins and possible additional auto antigens could be useful in laboratory evaluation of peripheral neuropathies and help to develop a more effective therapeutic approach

Immunoreactivity of glycoproteins isolated from human peripheral nerve and Campylobacter jejuni (O:19)

Objective: Antibodies to ganglioside GM1 are associated with Guillain-Barré Syndrome (GBS) in patients with serologic evidence of a preceding infection with Campylobacter jejuni. Molecular mimicry between C. jejuni Lipopolysaccharide (LPS) and ganglioside GM1 has been proven to be the immunopathogenic mechanism of the disease in the axonal variant of GBS. GM1-positive sera cross-react with several Gal-GalNAc-bearing glycoproteins from the human peripheral nerve and C. jejuni (O:19). This study aimed to examine the immunoreactivity of the digested cross-reactive glycoproteins isolated from the human peripheral nerve and C. jejuni (O:19) with Peanut Agglutinin (PNA) as a marker for the Gal-GalNAc determinant, and with sera from patients with GBS. Materials and Methods: For this purpose, the cross-reactive glycoproteins from peripheral nerve and C. jejuni (O:19) were enzymatically digested with trypsin and the obtained peptides were incubated with PNA and GBS sera. Results: Western blot analysis of the separated peptides revealed several bands showing positive reactivity to PNA and to sera from patients with GBS, present in both digests from peripheral nerve and C. jejuni (O:19). Conclusions: These data indicate the possible molecular mimicry between the cross-reactive glycoproteins present in C. jejuni and human peripheral nerve and its potential role in the development of GBS following infection with C. jejuni (O:19)