Monitoring of fluoride in water samples using a smartphone.

In several parts of India, groundwater is the only reliable, year round source for drinking water. Prevention of fluorosis, a chronic disease resulting from excess intake of fluoride, requires the screening of all groundwater sources for fluoride in endemic areas. In this paper, the authors present a field deployable colorimetric analyzer based on an inexpensive smartphone embedded with digital camera for taking photograph of the colored solution as well as an easy-fit, and compact sample chamber (Akvo Caddisfly). Phones marketed by different smartphone makers were used. Commercially available zirconium xylenol orange reagent was used for determining fluoride concentration. A software program was developed to use with the phone for recording and analyzing the RGB color of the picture. Linear range for fluoride estimation was 0-2mgl(-1). Around 200 samples, which consisted of laboratory prepared as well as field samples collected from different locations in Karnataka, India, were tested with Akvo Caddisfly. The results showed a significant positive correlation between Ion Selective Electrode (ISE) method and Akvo Caddisfly (Phones A, B and C), with correlation coefficient ranging between 0.9952 and 1.000. In addition, there was no significant difference in the mean fluoride content values between ISE and Phone B and C except for Phone A. Thus the smartphone method is economical and suited for groundwater fluoride analysis in the field.

Enterotoxigenicity screening of viable environmental Vibrio cholerae strains from rainwater pools in a university campus in Chennai, South India.

BACKGROUND: Vibrio spp., being primarily inhabitants of the aquatic environment, pose a severe health threat to humans. This problem is escalated in developing countries where water-logging after rainfall is very common. Therefore, screening of environmental water samples for the presence of clinically important species of Vibrio becomes essential. METHODS: This study was conducted for a period of 1 y. Water samples were collected every month from 4 locations where water pools formed after rains, on the campus of a university in Chennai, South India. The water samples were monitored for Vibrio species, and characterized isolates were screened for enterotoxigenicity. RESULTS: Thirty isolates of Vibrio cholerae belonging to a variety of serogroups and 11 strains of Vibrio species other than cholerae were isolated from the rainwater pools. On polymerase chain reaction (PCR) screening, while all the strains were positive for the ompW gene, none tested positive for the ctxA gene. CONCLUSIONS: Though all the environmental isolates of V. cholerae were non-epidemic, 4 isolates demonstrated enterotoxigenicity by rabbit ileal loop method and antibiotic resistance to drugs. This is of concern and underscores the importance of screening environmental specimens and improving civic infrastructure to prevent prolonged water-logging in developing countries.

Diabetic retinopathy: Validation study of ALR2, RAGE, iNOS and TNFB gene variants in a south Indian cohort.

PURPOSE: We previously reported the association of the Z-2 allele of the promoter dinucleotide repeat in the Aldose reductase (ALR2) gene, the (CCTTT)15 allele in the promoter of inductible nitric oxide synthase (iNOS) gene, and the (GT)13 promoter polymorphism in the tumor necrosis factor ß (TNFB) gene with an increased risk for diabetic retinopathy (DR), and the Gly82Ser polymorphism in the receptor for advanced glycation end products (RAGE) gene and the (GT)9 allele of the TNFB gene with low-risk for DR in a hospital-based self-reported type 2 diabetes mellitus (T2DM) patients. We have repeated the study in a population-based south Indian cohort to validate the same variations in these genes. MATERIALS AND METHODS: Type 2 diabetic patients with and without retinopathy (DR+ and DR- respectively) were recruited. (CA)(n) repeat, Gly82Ser, (CCTTT)(n) repeat and (GT)(n) repeat in ALR2, RAGE, iNOS and TNFB genes respectively were genotyped and their frequencies were analyzed using the relevant statistical tests. RESULTS: Different allelic associations were observed in the present study as compared to our previous reports. Z+2 allele of ALR2, 13-repeat genotype of iNOS, 15-repeat genotype of TNF-ß, genes were associated with susceptibility to DR. Gly82Ser polymorphisms of the RAGE gene were not associated with DR in the present study. CONCLUSION: The present data show a difference in the association of variations in ALR2, iNOS and TNFB genes with DR, when compared to our previous reports; this could be attributed to differences between the study populations of the past and present report.

Protein kinase C beta (PRKCB1) and pigment epithelium derived factor (PEDF) gene polymorphisms and diabetic retinopathy in a south Indian cohort.

PURPOSE: Polymorphisms in protein kinase C beta (PRKCB1) and pigment epithelium derived factor (PEDF) genes have been associated with diabetic nephropathy and retinopathy respectively. Association of promoter polymorphisms-1504C/T and-1440G/T in PRKCB1 gene and sequence variations in exon 4 of PEDF gene are studied with diabetic retinopathy (DR) in a south Indian population based cohort. METHODS: Type 2 diabetic patients with and without retinopathy (DR+ and DR- respectively) were recruited. The promoter region of PRKCB1 gene and exon 4 of PEDF genes were sequenced by polymerase chain reaction based direct sequencing and their frequencies were analyzed using relevant statistical tests. RESULTS: The genotype and alleles of the two promoter polymorphisms of PRKCB1 gene were uniformly distributed among DR+ and DR- and hence were not associated with the disease. The haplotypes were also not significantly associated with DR. A T130T polymorphism observed in the PEDF gene showed modest association with absence of diabetic retinopathy. CONCLUSION: Our results suggest lack of association of PRKCB1 gene promoter polymorphisms and moderate protective association of PEDF gene polymorphism with DR in the south Indian population.

Association of VEGF gene polymorphisms with diabetic retinopathy in a south Indian cohort.

BACKGROUND: Polymorphisms in vascular endothelial growth factor (VEGF) gene have been associated with diabetic retinopathy (DR) in various populations. A promoter polymorphism and a 3'UTR variation are studied for association with DR. MATERIALS AND METHODS: Type 2 diabetic patients with and without retinopathy were recruited. The -634C/G and 936C/T polymorphisms were genotyped by direct sequencing and their frequencies were analyzed using relevant statistical tests. RESULTS: No significant association was observed between genotypes, alleles and haplotypes of -634C/G and 936C/T polymorphisms and DR or its severity. However, C(-634)G genotype was found to increase the risk for DR in patients with microalbuminuria (OR: 8.9, 95% CI: 1.4, 58.3). CONCLUSION: Our study broadly suggests lack of association of VEGF gene polymorphisms with DR.

Diabetic retinopathy and IGF-1 gene polymorphic cytosine-adenine repeats in a Southern Indian cohort.

BACKGROUND/AIMS: Growth factors have been implicated in the pathogenesis of diabetic retinopathy (DR). IGF-1 is known to trigger a critical cascade of molecular events that initiate retinal angiogenesis. Increased vitreous IGF-1 levels have been correlated with the severity of ischemia-associated diabetic retinal neovascularization. In the present study, a cytosine-adenine (CA)(n) repeat in the promoter of the IGF-1 gene is studied for association with DR. METHODS: A total of 127 patients with retinopathy (cases: DR+) and 81 patients without retinopathy (controls: DR-) who had type 2 diabetes were recruited for the study. Patients underwent detailed clinical examination and DR was graded based on stereoscopic digital fundus photographs. Frequencies of alleles and genotypes between the two groups were analyzed for significance using relevant statistical tests. (CA)(17) and (CA)(18) repeats were the more frequent alleles. RESULTS: The frequency of the 18-repeat genotype was significantly higher in DR+ patients when compared to DR- patients and found to confer a 2.4 times (95% CI: 1.2-5.0) and 2.8 times (95% CI: 1.1-7.5) higher risk for developing DR and proliferative DR, respectively, when compared to <18-repeat genotypes. CONCLUSIONS: Our study suggests that the 18-repeat genotype is a susceptibility genotype for DR and its clinical severity in a Southern Indian cohort.