Effect of Ionic Liquid Electrolytes in DSSCs with Titanium Dioxide (TiO2) Inverse Opal Structures

Dye-sensitized solar cells (DSSC) are low-cost alternatives to conventional solar cells that can work well in low-light conditions. Despite considerable study on improving the efficiency of DSSCs, the current liquid electrolyte cell has plateaued at a conversion efficiency of ~ 12%. A major problem with these cells regarding their applicability is the low viscosity and high volatility of the toxic electrolyte, i.e., acetonitrile, which cause leakage and volatilization. We propose that using ionic liquids (ILs), which are more viscous, less volatile, and conductive, may be more suitable electrolytes. However, one unwanted side effect of the higher viscosity of the ILs may be an incomplete infiltration of the DSSC’s nanoporous TiO2 electrode. Here, we present a study of DSSCs with TiO2 inverse opal electrodes of controlled pore sizes (0.1-1 m) and ionic liquid derivatives of 1-alkyl-3-methylimidazolium tetrafluoroborate (alkyl: ethyl, butyl, and decyl) with viscosities ranging from 25.2 to 721 cP. The stability and functionality of the DSSCs is tested using electrochemical techniques that yield current-voltage and power curves

Epigenetics – an introductory overview

Epigenetics or imprinting refers to the process of ‘chemically’ marking the central A, C, G, T double-stranded DNA code. In the past several decades a deeper understanding has been gained of a wide range of mechanisms that have been invoked in biology for the purpose of regulating gene expression and dosage of protein products that are effectively translated and functional in the cells. We mostly carry two copies of a gene (one per non-sex chromosome inherited from each of our parents) in each of our somatic cells; however, some genes are required to have two functional copies in each cell, while others require no less than one copy, but are tolerant of more than one copy. There are very specific genes, often dealing with growth and development, which are, however, only ever needed in a single copy; any more or any less is problematic and even lethal. Epigenetics is the process of reversibly ‘marking’ genes, either driven by endogenous processes or through exposure to environmental factors, such that they may be effectively silenced. Human development requires an orderly and systematic means of switching on and off of genes; understandably, if there is a mutation affecting this process, it leads to disease, while exposure to chemicals or other experiential stimuli may have a similar effect. This review provides a broad outline of epigenetics and genetic imprinting on human and mammalian development and disease

Psychosis and relapse in bipolar disorder are related to GRM3 DAOA and GRIN2B genotype

Objective: Dysfunction in glutamate signalling is thought to play a role in the pathophysiology of bipolar disorder (BD). There is evidence of associations between single nucleotide polymorphisms (SNPs) in GRM3, GRIN2B, and DAOA genes and the diagnosis of BD. In this pilot study, we investigated the frequency of SNP variants in these 3 genes within South African population groups, and assessed interactions between genes and phenotypes of BD disease severity. Method: Multiplex SNaPshotTM PCR was used to genotype 191 case and 188 control samples. Cases comprised of 191 individuals in a South African cohort of mixed ancestry and Caucasians, with BD Type 1. Phenotypes of BD disease severity were: age of onset, number of illness episodes, number of hospitalisations for depression or mania and history of psychotic symptoms. Results: There were no significant difference in SNP allele frequencies between cases and controls. In the case-only analysis, the GRM3 rs6465084 heterozygote was associated with a 4-fold increased risk of lifetime history of psychotic symptoms, and the specific variants within the gene pair, DAOA and GRIN2B, had a significant interaction with the number of hospitalisations for mania, with lowest admission rates associated with both pairs of ancestral alleles.Conclusion: In BD, variations in glutamatergic genes may influence phenotypes related to the severity of illness. Speculatively, newly derived genes associated with various evolutionary advantages, may also increase the risk for more severe BD. These preliminary findings deserve validation in a larger cohort

Genetic variation within GRIN2B in adolescents with alcohol use disorder may be associated with larger left posterior cingulate cortex volume.

OBJECTIVE: Brain structure differences and adolescent alcohol dependence both show substantial heritability. However, exactly which genes are responsible for brain volume variation in adolescents with substance abuse disorders are currently unknown. The aim of this investigation was to determine whether genetic variants previously implicated in psychiatric disorders are associated with variation in brain volume in adolescents with alcohol use disorder (AUD). METHODS: The cohort consisted of 58 adolescents with DSM-IV AUD and 58 age and gender-matched controls of mixed ancestry ethnicity. An Illumina Infinium iSelect custom 6000 bead chip was used to genotype 5348 single nucleotide polymorphisms (SNPs) in 378 candidate genes. Magnetic resonance images were acquired and volumes of global and regional structures were estimated using voxel-based morphometry. To determine whether any of the genetic variants were associated with brain volume, association analysis was conducted using linear regression in Plink. RESULTS: From the exploratory analysis, the GRIN2B SNP rs219927 was associated with brain volume in the left posterior cingulate cortex (p<0.05), whereby having a G-allele was associated with a bigger volume. CONCLUSION: The GRIN2B gene is involved in glutamatergic signalling and may be associated with developmental differences in AUD in brain regions such as the posterior cingulate cortex. Such differences may play a role in risk for AUD, and deserve more detailed investigation

Psychosis and relapse in bipolar disorder are related to GRM3, DAOA, and GRIN2B genotype

Objective:  Key Words: Manic-Depressive Psychosis; Glutamate; GRIN2B receptor; mGluR3; G72 protein; HumanDysfunction in glutamate signalling is thought to play a role in the pathophysiology of bipolar disorder (BD). There is evidence of associations between single nucleotide polymorphisms (SNPs) in GRM3, GRIN2B, and DAOA genes and the diagnosis of BD. In this pilot study, we investigated the frequency of SNP variants in these 3 genes within South African population groups, and assessed interactions between genes and phenotypes of BD disease severity. Method: Multiplex SNaPshotTM PCR was used to genotype 191 case and 188 control samples. Cases comprised of 191 individuals in a South African cohort of mixed ancestry and Caucasians, with BD Type 1. Phenotypes of BD disease severity were: age of onset, number of illness episodes, number of hospitalisations for depression or mania and history of psychotic symptoms. Results: There were no significant difference in SNP allele frequencies between cases and controls. In the case-only analysis, the GRM3 rs6465084 heterozygote was associated with a 4-fold increased risk of lifetime history of psychotic symptoms, and the specific variants within the gene pair, DAOA and GRIN2B, had a significant interaction with the number of hospitalisations for mania, with lowest admission rates associated with both pairs of ancestral alleles. Conclusion: In BD, variations in glutamatergic genes may influence phenotypes related to the severity of illness. Speculatively, newly derived genes associated with various evolutionary advantages, may also increase the risk for more severe BD. These preliminary findings deserve validation in a larger cohort

New-onset diabetes after transplant: Incidence, risk factors and outcome

Background. The outcome of renal transplantation depends on achieving effective immunosuppression while minimising the consequences of such treatment. The occurrence of new-onset diabetes in the post-transplant period has been associated with several risk factors including some immunosuppressive medication. Better understanding of the clinical and genetic risk factors associated with new-onset diabetes after transplant (NODAT) could enable risk stratification of patients in the pre-transplant period, with the goal of applying measures that will reduce the incidence.Objectives. To ascertain the incidence of and clinical and genetic risk factors that predispose to NODAT, and to examine its effect on the outcome of renal transplantation.Methods. We performed a retrospective cohort review of all renal transplants at Groote Schuur Hospital, Cape Town, South Africa, between 2004 and 2008. Patients who were lost to follow-up or had pre-transplant diabetes or primary non-function were excluded. A subset of the cohort who gave informed consent was enlisted for genetic tests.Results. We identified 111 patients who met the inclusion criteria. The incidence of NODAT was 18.0% (n=20 patients). Risk factors for NODAT included age at transplant (p=0.03), body weight (p=0.04), treatment for acute cellular rejection (p=0.02) and polycystic kidney disease as the cause of renal failure (p=0.005). None of the genes investigated (TCF7L2 rs11196205, rs12255372 and rs7903146 and HNF1β rs1800575, rs121918671 and rs121918672) was found to be significantly associated with the risk of NODAT. The genotype frequencies for the single-nucleotide polymorphisms studied were closer (although not identical) to those reported for Caucasians than to those reported for the Yoruba (black) population in West Africa. Overall patient survival was 78% at five years, while graft survival was 72%. There was no significant difference in patient or graft survival between the group with NODAT and the group without.Conclusions. NODAT was common in renal transplant recipients. Some risk factors predate transplant and could be used to risk-stratify patients to determine appropriate risk-reduction strategies. The genetic determinants for NODAT in this population may differ from those reported elsewhere. NODAT had no impact on patient or graft survival in this cohort

Association of variants at BCL11A and HBS1L-MYB with hemoglobin F and hospitalization rates among sickle cell patients in Cameroon

BACKGROUND: Genetic variation at loci influencing adult levels of HbF have been shown to modify the clinical course of sickle cell disease (SCD). Data on this important aspect of SCD have not yet been reported from West Africa. We investigated the relationship between HbF levels and the relevant genetic loci in 610 patients with SCD (98% HbSS homozygotes) from Cameroon, and compared the results to a well-characterized African-American cohort. Methods and FINDINGS: Socio-demographic and clinical features were collected and medical records reviewed. Only patients >5 years old, who had not received a blood transfusion or treatment with hydroxyurea were included. Hemoglobin electrophoresis and a full blood count were conducted upon arrival at the hospital. RFLP-PCR was used to describe the HBB gene haplotypes. SNaPshot PCR, Capillary electrophoresis and cycle sequencing were used for the genotyping of 10 selected SNPs. Genetic analysis was performed with PLINK software and statistical models in the statistical package R. Allele frequencies of relevant variants at BCL11A were similar to those detected in African Americans; although the relationships with Hb F were significant (p <.001), they explained substantially less of the variance in HbF than was observed among African Americans (∼ 2% vs 10%). SNPs in HBS1L-MYB region ( HMIP ) likewise had a significant impact on HbF, however, we did not find an association between HbF and the variations in HBB cluster and OR51B5/6 locus on chromosome 11p, due in part to the virtual absence of the Senegal and Indian Arab haplotypes. We also found evidence that selected SNPs in HBS1L-MYB region ( HMIP ) and BCL11A affect both other hematological indices and rates of hospitalization. CONCLUSIONS: This study has confirmed the associations of SNPs in BCL11A and HBS1L-MYB and fetal haemoglobin in Cameroonian SCA patients; hematological indices and hospitalization rates were also associated with specific allelic variants