Karuppiah Balakrishnan

A major susceptibility locus for leprosy in India maps to chromosome 10p13

Leprosy, a chronic infectious disease caused by Mycobacterium leprae, is prevalent in India, where about half of the worlds estimated 800,000 cases occur. A role for the genetics of the host in variable susceptibility to leprosy has been indicated by familial clustering, twin studies, complex segregation analyses and human leukocyte antigen (HLA) association studies. We report here a genetic linkage scan of the genomes of 224 families from South India, containing 245 independent affected sibpairs with leprosy, mainly of the paucibacillary type. In a two-stage genome screen using 396 microsatellite markers, we found significant linkage (maximum lod score (MLS)=4.09, P<2×10−5) on chromosome 10p13 for a series of neighboring microsatellite markers, providing evidence for a major locus for this prevalent infectious disease. Thus, despite the polygenic nature of infectious disease susceptibility, some major, non-HLA–linked loci exist that may be mapped through obtainable numbers of affected sibling pairs.

A Region of Chromosome 20 Is Linked to Leprosy Susceptibility in a South Indian Population

A major susceptibility locus for leprosy has recently been mapped on chromosome 10 (10p13) by genome-wide linkage analysis. Microsatellite markers from this genome screen that showed suggestive evidence of linkage to leprosy were evaluated in an additional 140 families with affected sib pairs. A second region of linkage has thus been identified on chromosome 20 (20p12). The peak of linkage lies at marker D20S115, which has a significant single-point maximum logarithm of odds score of 3.48 (P=.00003). Transmission disequilibrium testing of the microsatellite markers in 20p12 showed that the marker D20S835 is associated with protection against leprosy (P=.021), which suggests that a locus controlling susceptibility lies close to this marker.

Susceptible and protective associations of HLA DRB1*/DQB1* alleles and haplotypes with ischaemic stroke.

Stroke has emerged as the second commonest cause of mortality worldwide and is a major public health problem. For the first time, we present here the association of human leucocyte antigen (HLA)‐DRB1*/DQB1* alleles and haplotypes with ischaemic stroke in South Indian patients. Ischaemic stroke (IS) cases and controls were genotyped for HLA‐DRB1*/DQB1* alleles by polymerase chain reaction sequence‐specific primers (PCR‐SSP) method. The frequencies of HLA class II alleles such as DRB1*04, DRB1*07, DRB1*11, DRB1*12, DRB1*13, DQB1*02 and DQB1*07 were high in IS patients than in the age‐ and gender‐matched controls, suggesting that the individuals with these alleles are susceptible to ischaemic stroke in South India. The frequencies of alleles such as DRB1*03, DRB1*10, DRB1*14, DQB1*04 and DQB1*05 were less in IS cases than in the controls, suggesting a protective association. Haplotypes DRB1*04‐DQB1*0301, DRB1*07‐DQB1*02, DRB1*07‐DQB1*0301, DRB1*11‐DQB1*0301 and DRB1*13‐DQB1*06 were found to be high in IS patients conferring susceptibility. The frequency of haplotype DRB1*10‐DQB1*05 was high in controls conferring protection. IS‐LVD and gender‐stratified analysis too confirmed these susceptible and protective associations. Thus, HLA‐DRB1*/DQB1* alleles and haplotypes strongly predispose South Indian population to ischaemic stroke. Further studies in different populations with large sample size or the meta‐analysis are needed to explain the exact mechanism of associations of HLA gene(s) with IS.

Synthesis of Polythiophene and its Carbonaceous Nanofibers as Electrode Materials for Asymmetric Supercapacitors

A highly porous polythiophene (PTh) nanofibers were synthesized by surfactant assisted dilute polymerization method using FeCl3 as oxidant. They were confirmed by XRD and FTIR analysis. The surface morphology of PTh was done by scanning electron microscopy (SEM). The prepared polythiophene nanofibers were subjected to calcination under inert gas atmosphere at 1400oC for 2 hrs to get carbonaceous PTh nanofibers. The asymmetric supercapacitor was assembled using PTh nanofibers as the cathode and carbonaceous PTh nanofibers as the anode in 6M KOH electrolyte. The electrochemical supercapacitor performances were carried out to find out the specific capacitance, energy density and power density of the cell. The above results confirmed that the prepared PTh nanofibers and carbonaceous PTh nanofibers could be used as electrode materials for asymmetric supercapacitor applications. Keywords: Polythiophene, Dilute polymerization method, Carbonaceous material, Asymmetric supercapacitor, Specific capacitances

Critical amino acid variations in HLA-DQB1* molecules confers susceptibility to Autoimmune Thyroid Disease in south India

The HLA-DQB1* region exhibits complex associations with autoimmune thyroid disease (AITD). AITD patients (Hashimoto’s thyroiditis, HT = 180; Graves’ disease, GD = 55) and age/sex matched controls (n = 235) were genotyped for DQB1* alleles by PCR-SSP. Alleles DQB1*02:02, *06:03, *06:09, *03:02, and *03:03 showed an increased risk and *02:01, *05:02, and *06:02 showed a protection toward AITD. Multiple sequence alignment was used to find out the amino acid variations within the peptide-binding pockets of susceptible and/or protective DQB1* alleles. We observed susceptible associations for amino acids ‘Glu86(P < 0.0007)’ and ‘Leu87(P < 3.8 × 10−4)’ in P1, ‘Leu26(P < 4.0 × 10−12)’ in P4, ‘His9(P < 5.0 × 10−4)’ and ‘Ala57(P < 3.6 × 10−4)’ in P9 toward HT; and ‘Gly86(P < 0.0004)’ in P1 and ‘Asp57(P < 1.9 × 10−4)’ in P9 towards GD. Protective associations were observed for amino acids ‘Ala86(P < 8.2 × 10−6)’ and ‘Tyr87(P < 0.0003)’ in P1, ‘Gly26(P < 4.9 × 10−5)’ and ‘Ser74(P < 4.9 × 10−5)’ in P4, ‘Phe9(P < 0.0007)’ and ‘Ser57(P < 0.0016)’ in P9 towards HT. Thus, the present study revealed that DQB1* alleles and putative amino acid residues play an important role in susceptibility toward AITD in south India.

RAPSTROM™ first-in-man study long-term results of a biodegradable polymer sustained-release sirolimus-eluting stent in de novo coronary stenoses.

BACKGROUND Durable polymers used for first-generation drug-eluting stents (DES) potentially contribute to persistent inflammation and late DES thrombosis. We report the first real-life human experience with the rapamycin-eluting biodegradable polymer-coated Rapstrom stent. METHODS All consecutive patients with single de novo native coronary stenosis (<30 mm and between 2.5 and 4.0 mm) were enrolled. Major adverse cardiac events (MACE) at 1 year (cardiac death, myocardial infarction [Q and non-Q], or ischemia-driven target lesion revascularization) were the primary end-point. RESULTS A total of 123 patients were enrolled. The stent was implanted without complications in all patients, and no MACE were recorded at 30 days. At 12-month follow-up 9 patients (7.3%) experienced a MACE and 4 (3.2%) required a target lesion revascularization, while 1 (1%) stent thrombosis was recorded. A planned angiographic follow-up (FU) was performed in 73 patients (59%) at 9.4 ± 2.6 months following the index procedure. In-stent late loss was 0.16 ± 0.09 mm, and in-segment late loss was 0.18 ± 0.8 mm. CONCLUSION The Rapstrom biodegradable polymer rapamycin-eluting stent appeared safe and efficacious in this first real-life human experience, due to a low late lumen loss. Larger randomized studies are required to confirm these preliminary results.

Molecular Cloning and Docking of speB Gene Encoding Cysteine Protease With Antibiotic Interaction in Streptococcus pyogenes NBMKU12 From the Clinical Isolates

Streptococcus pyogenes causes a variety of diseases ranging from mild diseases to severe invasive infections which result in significant morbidity and mortality. This study focuses on the antibiotic resistance of S. pyogenes and their interaction with cysteine protease. Around 36 beta-hemolytic isolates were collected from the clinical lab, of which seven isolates (19.4%) were identified as Streptococcus pyogenes. One of the seven isolates was collected from a urinary tract infection, which was identified by antibody agglutination and MALTI-TOF-MS, and it is designated as S. pyogenes NBMKU12. Around 8.3 to 66.6 % of the isolates were found to be resistant to one or more antimicrobial agents, especially, penicillin-G resistance was exhibited by 29.1% of the isolates. In the NBMKU12 isolate, the beta lactem (TEM) gene was detected among the 13 antibiotic genes for which it was tested. Furthermore, when analysis for presence of 13 virulence genes were carried out in NBMKU12 isolate, only speJ and speB were detected. The speB (streptococcal pyrogenic exotoxin B) encoding cysteine protease gene was cloned. This was followed by performing DNA sequencing to understand the putative cysteine protease interaction with antibiotics, inhibitors, and substrate. The speB gene consists of 1197 nucleotides and encodes a protein with multiple domains, including a signal peptide (aa 1–22), an inhibitor region (aa 27–156), and a catalytic cysteine domain (aa 160–367). The signal peptide cleavage site is predicted between Ala22 and Asn23. The putative 398 amino acid residues were found to have a theoretical pI of 8.76 and a molecular mass of 43,204.36 Da. The tested culture supernatants of NBMKU12 isolate exhibited the proteolytic activity against casein, papaya and pineapple used as substrates. The proteolytic activity suggests the expression of speB gene. Molecular docking analysis of cysteine protease showed that erythromycin (bond length 2.41 Å), followed by chloramphenicol (2.51 Å), exhibited a strong interaction; while penicillin-G (3.24 Å) exhibited a weak interaction, and this factor could be considered as a cause for penicillin-G resistance. The present study contributes to a better understanding of speB gene encoding cysteine protease, antibiotic resistance, and their interaction in the isolate, S. pyogenes NBMKU12. The antibiotics and cysteine protease interaction study confirms the resistance or sensitivity of S. pyogenes. Hence, it could be hypothesized that the isolate NBMKU12 is resistant to most of the tested antibiotics, and this resistance might be a cause for mutation.

Nanocerium oxide increases the survival of adult rod and cone photoreceptor in culture by abrogating hydrogen peroxide-induced oxidative stress

In vitro cell culture system for adult rod and cone photoreceptor (PR) is an effective and economical model for screening drug candidates against all kinds of age related retinal blindness. Interestingly, adult PR cells have a limited survival in the culture system, thus preventing full exploitation of this in vitro approach for drug screening applications. The limited survival of the adult PR cells in culture is due to their inherently high oxidative stress and photic injury. Mixed valence-state ceria nanoparticles have the ability to scavenge free radicals and reduce oxidative stress. Here, ceria nanoparticles of 5-10 nm dimensions have been synthesized, possessing dual oxidation state (+3 and +4) as evident from x-ray photoelectron spectroscopy and exhibiting real time reduction of hydrogen peroxide (H2O2) as quantified by absorbance spectroscopy and cyclic voltammogram analysis. Using flow cytometry and cell culture assay, it has been shown that, upon one time addition of 10 nM of nanoceria in the PR culture of the 18 months old adult common carp (Cyprinus carpio) at the time of plating the cells, the oxidative stress caused due to hydrogen peroxide assault could be abrogated. A further single application of nanoceria significantly increases the survival of these fragile cells in the culture, thus paving way for developing a more robust photoreceptor culture model to study the aging photoreceptor cells in a defined condition.