Guillain-Barré syndrome as a cause of acute flaccid paralysis in Iraqi children: a result of 15 years of nation-wide study

Background

Guillain-Barré syndrome (GBS) is the most common cause of acute flaccid paralysis (AFP) in the post-poliomyelitis eradication era. This is the first study done to identify the epidemiology, clinical features, and outcome of GBS in Iraqi children over 15 years.

Methods

The surveillance database about AFP cases?<?15 years reported during January 1997-December 2011 was used.

Results

GBS represented 52.5% of AFP cases, with an incidence of 1.33 case/100,000 population?<?15 years/year. There was a higher incidence in the Southern provinces, age group 1–4 years, males, and outside the capital city of province, with no significant seasonal variations (p?=?.22). Survival probability after the 1 year of onset for those with respiratory muscle involvement was .76 (95% CI: .60-.86), versus .97 (95% Cl: .96-.98) for those who did not develop it (p?<?.001); and .97 (95% CI: .96-.98) for those living inside the capital city, versus .94 (.93-.95) for those living outside (p?=?.001). Cumulative incidence of residual paralysis for patients living inside the capital city was .21 (95% CI: .18-.24), versus .27 (95% CI: .25-.29) for those living outside (p?<?.001).

Conclusions

The incidence, age and gender distribution, and seasonality of GBS among Iraqi children is similar to those reported from other previous studies. It is the most important cause of AFP, especially in those between the age of 1 to 4 years living in rural areas.

     

Differentiation of Fanconi anemia and aplastic anemia using mitomycin C test in Tunisia

Fanconi anemia (FA) is a recessive chromosomal instability syndrome that is clinically characterized by multiple symptoms. Chromosome breakage hypersensitivity to alkylating agents is the gold standard test for FA diagnosis. In this study, we provide a detailed laboratory protocol for accurate assessment of FA diagnosis based on mitomycin C (MMC) test. Induced chromosomal breakage study was successful in 171 out of 205 aplastic anemia (AA) patients. According to the sensitivity of MMC at 50 ng/ml, 38 patients (22.22%) were diagnosed as affected and 132 patients (77.17%) as unaffected. Somatic mosaicism was suspected in an 11-year-old patient with a FA phenotype. Twenty-six siblings of FA patients were also evaluated and five of them (19.23%) were diagnosed as FA. From this study, a standard protocol for diagnosis of FA was developed. It is routinely used as a diagnostic test of FA in Tunisia.     

The octadecaneuropeptide ODN prevents 6‐hydroxydopamine‐induced apoptosis of cerebellar granule neurons through a PKC‐MAPK‐dependent pathway

Oxidative stress, induced by various neurodegenerative diseases, initiates a cascade of events leading to apoptosis, and thus plays a critical role in neuronal injury. In this study, we have investigated the potential neuroprotective effect of the octadecaneuropeptide (ODN) on 6‐hydroxydopamine (6‐OHDA)‐induced oxidative stress and apoptosis in cerebellar granule neurons (CGN). ODN, which is produced by astrocytes, is an endogenous ligand for both central‐type benzodiazepine receptors (CBR) and a metabotropic receptor. Incubation of neurons with subnanomolar concentrations of ODN (10^?18 to 10^?12 M) inhibited 6‐OHDA‐evoked cell death in a concentration‐dependent manner. The effect of ODN on neuronal survival was abrogated by the metabotropic receptor antagonist, cyclo_1–8[DLeu⁵]OP, but not by a CBR antagonist. ODN stimulated polyphosphoinositide turnover and ERK phosphorylation in CGN. The protective effect of ODN against 6‐OHDA toxicity involved the phospholipase C/ERK MAPK transduction cascade. 6‐OHDA treatment induced an accumulation of reactive oxygen species, an increase of the expression of the pro‐apoptotic gene Bax, a drop of the mitochondrial membrane potential and a stimulation of caspase‐3 activity. Exposure of 6‐OHDA‐treated cells to ODN blocked all the deleterious effects of the toxin. Taken together, these data demonstrate for the first time that ODN is a neuroprotective agent that prevents 6‐OHDA‐induced oxidative stress and apoptotic cell death.     

Molecular bases for sensitivity to tubulin-binding herbicides in green foxtail

We investigated the molecular bases for resistance to several classes of herbicides that bind tubulins in green foxtail (Setaria viridis L. Beauv.). We identified two alpha- and two beta-tubulin genes in green foxtail. Sequence comparison between resistant and sensitive plants revealed two mutations, a leucine-to-phenylalanine change at position 136 and a threonine-to-isoleucine change at position 239, in the gene encoding alpha2-tubulin. Association of mutation at position 239 with herbicide resistance was demonstrated using near-isogenic lines derived from interspecific pairings between green foxtail and foxtail millet (Setaria italica L. Beauv.), and herbicide sensitivity bioassays combined with allele-specific PCR-mediated genotyping. Association of mutation at position 136 with herbicide resistance was demonstrated using herbicide sensitivity bioassays combined with allele-specific PCR-mediated genotyping. Both mutations were associated with recessive cross resistance to dinitroanilines and benzoic acids, no change in sensitivity to benzamides, and hypersensitivity to carbamates. Using three-dimensional modeling, we found that the two mutations are adjacent and located into a region involved in tubulin dimer-dimer contact. Comparison of three-dimensional alpha-tubulin models for organisms with contrasted sensitivity to tubulin-binding herbicides enabled us to propose that residue 253 and the vicinity of the side chain of residue 251 are critical determinants for the differences in herbicide sensitivity observed between organisms, and that positions 16, 24, 136, 239, 252, and 268 are involved in modulating sensitivity to these herbicides.     

IL-10R1 S138G loss-of-function polymorphism is associated with extrapulmonary tuberculosis risk development in Tunisia

There is considerable evidence that host genetic factors are important in determining susceptibility to mycobacterial infections. More recently, functional genetic mutations affecting IL-10 receptor 1 (IL-10R1) were described. In this study, we investigated the relationship of IL-10R1 S138G loss-of-function polymorphism (A536G: rs3135932) with susceptibility to active tuberculosis (TB) in Tunisian patients. A total of 168 patients with pulmonary TB, 55 with extrapulmonary TB, and 150 control subjects were studied. Genomic DNA samples were extracted from leukocytes and used to investigate S138G polymorphism in IL-10R1 gene by multiplex allele-specific polymerase chain reaction. Associations between G allele [odds ratio OR = 5.01; 95% confidence intervals CI = 2.58–9.77; P = 10⁻⁷], GG genotypes [OR=9.06; 95% CI (1.58–67.33); correcting P-values using the Bonferroni method for multiple tests Pc=0.015] and AG genotype [OR=3.75; 95% CI (1.62–8.7); Pc=0.0012] with the risk development of active extrapulmonary TB were found. In contrast, the AA genotype was found to be associated with resistance to extrapulmonary TB [OR=0.19; 95% CI (0.09–0.42); Pc=6.10⁻⁶]. No association was found between S138G SNP and pulmonary TB. In conclusion, our study suggested the possible role of IL-10R1 S138G loss-of-function polymorphism in extrapulmonary TB susceptibility-resistance in Tunisia.     

Endogenous Expression of ODN-Related Peptides in Astrocytes Contributes to Cell Protection Against Oxidative Stress: Astrocyte-Neuron Crosstalk Relevance for Neuronal Survival

Astroglial cells are important actors in the defense of brain against oxidative stress injuries. Glial cells synthesize and release the octadecaneuropeptide ODN, a diazepam-binding inhibitor (DBI)-related peptide, which acts through its metabotropic receptor to protect neurons and astrocytes from oxidative stress-induced apoptosis. The purpose of the present study is to examine the contribution of the endogenous ODN in the protection of astrocytes and neurons from moderate oxidative stress. The administration of H₂O₂ (50 μM, 6 h) induced a moderate oxidative stress in cultured astrocytes, i.e., an increase in reactive oxygen species, malondialdehyde, and carbonyl group levels, but it had no effect on astrocyte death. Mass spectrometry and QPCR analysis revealed that 50 μM H₂O₂ increased ODN release and DBI mRNA levels. The inhibition of ODN release or pharmacological blockage of the effects of ODN revealed that in these conditions, 50 μM H₂O₂ induced the death of astrocytes. The transfection of astrocytes with DBI siRNA increased the vulnerability of cells to moderate stress. Finally, the addition of 1 nM ODN to culture media reversed cell death observed in DBI-deficient astrocytes. The treatment of neurons with media from 50 μM H₂O₂-stressed astrocytes significantly reduced the neuronal death induced by H₂O₂; this effect is greatly attenuated by the administration of an ODN metabotropic receptor antagonist. Overall, these results indicate that astrocytes produce authentic ODN, notably in a moderate oxidative stress situation, and this glio- and neuro-protective agent may form part of the brain defense mechanisms against oxidative stress injury.     

Does the dysregulation of matrix metalloproteinases contribute to recurrent implantation failure?

Introduction: The progress in in vitro fertilization (IVF) techniques for infertility management has led to the investigation of embryo implantation site proteins such as Matrix metalloproteinases (MMPs), which may have a key role in embryo-endometrium crosstalk and in the molecular mechanisms of the embryo implantation.

Areas covered: Numerous studies have generated much information concerning the relation between the different proteins at the site of implantation such as cytokines, growth factors, adhesion molecules and MMPs. However, the exact role of the MMPs in embryo implantation and the impact of their dysregulation in recurrent implantation failure have yet to be characterized.

Expert commentary: The proteomic investigation of the MMPs and their molecular pathways may enable scientists and clinicians to correct this dysregulation (via appropriate means of prevention and treatment), better manage embryo transfer during IVF cycles, and thus increase the ongoing pregnancy rate.     

E. coli Nissle microencapsulation in alginate-chitosan nanoparticles and its effect on Campylobacter jejuni in vitro

Microencapsulation enhances the oral delivery of probiotic bacteria. In this study, the probiotic Escherichia coli Nissle 1917 (EcN) was microencapsulated using alginate and chitosan nanoparticles. The result showed 90% encapsulation yield of EcN, and the encapsulated EcN displayed significantly (P < 0.05) increased survival in low pH (1.5), high bile salt concentration (4%), and high temperature (70 °C). The most effective cryopreservatives of EcN during freezing and thawing was skim milk and sucrose. Exposure to microencapsulated EcN significantly (P < 0.05) reduced the Campylobacter jejuni growth by 2 log CFU. The rate of EcN release from microcapsule was 9.2 × 10⁵ cell min⁻¹, and the appropriate model to describe its release kinetics was zero order. Importantly, the entrapment of EcN inside the microcapsule did not eliminate the exterior diffusion of EcN produced antioxidant compounds. In addition, the EcN microcapsule efficiently adhered to intestinal HT-29 cells and the pre-treatment of HT-29 cells with EcN-microcapsule for 4 h significantly (P < 0.05) reduced the invasion (1.9 log) of C. jejuni; whereas, completely abolished the intracellular survival. Furthermore, HT-29 cells pre-treated with encapsulated EcN in PCR array showed decreased expression (> 1.5-fold) of genes encoding chemokines, toll-like receptors, interleukins, and tumor necrosis factors. In conclusion, the alginate-chitosan microcapsule can provide effectual platform to deliver probiotic EcN and thereby can reduce the Campylobacter infection in chickens and humans.

     

Mutation spectrum of primary hyperoxaluria type 1 in Tunisia: Implication for diagnosis in North Africa

Background

Primary hyperoxaluria type 1 (PH1) is an autosomal recessive inherited metabolic disease, characterized by progressive kidney failure due to renal deposition of calcium oxalate. Mutations in the AGXT gene, encoding the liver-specific enzyme alanine glyoxylate aminotransferase, are responsible for the disease. We aimed to determine the mutational spectrum causing PH1 and to provide an accurate tool for diagnosis as well as for prenatal diagnosis in the affected families.

Methods

Direct sequencing was used to detect mutations in the AGXT gene in DNA samples from 13 patients belonging to 12 Tunisian families.

Results

Molecular analysis revealed five mutations causing PH1 in Tunisia. The mutations were identified along exons 1, 2, 4, 5 and 7. The most predominant mutations were the Maghrebian “p.I244T” and the Arabic “p.G190R”. Furthermore, three other mutations characteristic of different ethnic groups were found in our study population. These results confirm the mutational heterogeneity related to PH1 in Tunisian population. All the mutations are in a homozygous state, reflecting the high impact of endogamy in our population.

Conclusion

Mutation analysis through DNA sequencing can provide a useful first line investigation for PH1. This identification could provide an accurate tool for prenatal diagnosis, genetic counseling and screen for potential presymptomatic individuals.