Triaxially uniform high-quality Al x Ga(1-x)N (x ∼ 50%) nanowires on template free sapphire substrate.

We have demonstrated the growth of high-quality Al x Ga(1-x)N (x âˆ¼ 50%) nanowires (NWs) for the first time on the sapphire substrate without using GaN NWs as the template, by plasma-assisted molecular beam epitaxy. Our newly developed process elucidates that depending on the substrate temperature and V/III ratio an AlGaN network is formed on sapphire substrate prior to the NWs growth. We find that the ledges of this kinked shaped network act as nucleation sites for the NW growth. The present observations suggest that availability of nucleation sites and higher substrate temperature during growth are the key parameters for the growth of homogeneous AlGaN NWs on the sapphire substrates. Energy dispersive x-ray spectroscopy, high-resolution transmission electron microscopy, Raman spectroscopy, x-ray diffraction, photoluminescence spectroscopy, and scanning electron microscopy analysis show that AlGaN NWs exhibit near-atomic scale compositional uniformity along the length as well as across the diameter.

Antibiotic Susceptibility Pattern of Bacteria Isolated From Various Specimens of Patients with Hematological Malignancy.

Infection is a life threatening complication in patients with hematological malignancy. So, proper treatment of infection with suitable antibiotic is very important in these patients. The aim of this study was to determine the antibiotic susceptibility of bacteria isolated from various specimens of patients with hematological malignancy, so that, an appropriate regimen of empiric antibiotic treatment can be established for these patients. This observational study was done in the Department of Microbiology and Immunology, Bangabandhu Sheikh Mujib Medical University (BSMMU), Dhaka, Bangladesh from March 2012 to August 2012. Forty (40) diagnosed patients of hematological malignancies who were admitted in the Department of Hematology and Paediatric Hemato-oncology, BSMMU with symptoms of sepsis &/ or urinary tract infection (UTI) or respiratory tract infection (RTI) were enrolled in this study. Blood, throat swab and urine were collected from each patient and sputum was collected from four patients. Susceptibility pattern of Gram positive bacteria to antibiotics was satisfactory. But Gram negative bacteria were resistant to commonly used antibiotics. Enterobacteriaceae group of organisms were found completely resistant to Ceftriaxone & Aztreonam. The best drugs for them were Imipenem, Amikacin & Netilmicin. P. aeruginosa & Acinetobacter spp. were completely resistant to several antibiotics including Cephalosporines & Ciprofloxacin. The best drug for them was Imipenem, Netilmicin & combination of Tazobactam & Piperacilin.

Immunization of Mice with a Live Transconjugant Shigella Hybrid Strain Induced Th1 and Th17 Cell-Mediated Immune Responses and Confirmed Passive Protection Against Heterologous Shigellae.

An avirulent, live transconjugant Shigella hybrid (LTSHΔstx) strain was constructed in our earlier study by introducing a plasmid vector, pPR1347, into a Shiga toxin gene deleted Shigella dysenteriae 1. Three successive oral administrations of LTSHΔstx to female adult mice produced comprehensive passive heterologous protection in their offspring against challenge with wild-type shigellae. Production of NO and different cytokines such asIL-12p70, IL-1ß and IL-23 in peritoneal mice macrophages indicated that LTSHΔstx induced innate and adaptive immunity in mice. Furthermore, production of IFN-γ, IL-10 and IL-17 in LTSH-primed splenic CD4+ T cell suggested that LTSHΔstx may induce Th1 and Th17 cell-mediated immune responses. Exponential increase of the serum IgG and IgA titre against whole shigellae was observed in immunized adult mice during and after the immunization with the highest peak on day 35. Antigen-specific sIgA was also determined from intestinal lavage of immunized mice. The stomach extracts of neonates from immunized mice, mainly containing mother's milk, contained significant levels of anti-LTSHΔstx immunoglobulin. These studies suggest that the LTSHΔstx could be a new live oral vaccine candidate against shigellosis in the near future.

Artificial Intelligence-based automated CT brain interpretation to accelerate treatment for acute stroke in rural India: An interrupted time series study.

In resource-limited settings, timely treatment of acute stroke is dependent upon accurate diagnosis that draws on non-contrast computed tomography (NCCT) scans of the head. Artificial Intelligence (AI) based devices may be able to assist non-specialist physicians in NCCT interpretation, thereby enabling faster interventions for acute stroke patients in these settings. We evaluated the impact of an AI device by comparing the time to intervention (TTI) from NCCT imaging to significant intervention before (baseline) and after the deployment of AI, in patients diagnosed with stroke (ischemic or hemorrhagic) through a retrospective interrupted time series analysis at a rural hospital managed by non-specialists in India. Significant intervention was defined as thrombolysis or antiplatelet therapy in ischemic strokes, and mannitol for hemorrhagic strokes or mass effect. We also evaluated the diagnostic accuracy of the software using the teleradiologists' reports as ground truth. Impact analysis in a total of 174 stroke patients (72 in baseline and 102 after deployment) demonstrated a significant reduction of median TTI from 80 minutes (IQR: 56·8-139·5) during baseline to 58·50 (IQR: 30·3-118.2) minutes after AI deployment (Wilcoxon rank sum test-location shift: -21·0, 95% CI: -38·0, -7·0). Diagnostic accuracy evaluation in a total of 864 NCCT scans demonstrated the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) in detecting intracranial hemorrhage to be 0·89 (95% CI: 0·83-0·93), 0·99 (0·98-1·00), 0·96 (0·91-0·98) and 0·97 (0·96-0·98) respectively, and for infarct these were 0·84 (0·79-0·89), 0·81 (0·77-0·84), 0·58 (0·52-0·63), and 0·94 (0·92-0·96), respectively. AI-based NCCT interpretation supported faster abnormality detection with high accuracy, resulting in persons with acute stroke receiving significantly earlier treatment. Our results suggest that AI-based NCCT interpretation can potentially improve uptake of lifesaving interventions for acute stroke in resource-limited settings.

Seropositivity of Helicobacter Pylori among the fish handlers.

This case control study was done to study the seropositivity of helicobacter pylori among the fish handlers and to find out rapid urease test (RUT) & haematoxillin and eosin staining report correlation of seropositive cases. It was performed among fish handlers in the period of July 2005 to June 2006. Blood samples were collected from fish handlers (Group I) and some non-fish handler control subjects (Group II) to perform Anti-H. Pylori IgG test by ELISA method. Samples were collected from both the sea water area (Paikgacha, Khulna) and fresh water area (Derai, Sunamgonj and Dhaka). Seropositive cases having complaints and treatment history of peptic ulcer diseases were motivated for endoscopic examination to collect biopsy from upper GIT and rapid urease test (RUT) hematoxillin & eosin (H & E) staining were performed. A total of 235 respondents were included in this study, among them 163 were fish handlers (80 sea water and 83 fresh water) and 72 were non fish handler control (25 sea water, 22 fresh water from Sunamgonj, 25 fresh water from Dhaka city). Serum anti- H. pylori test was positive in 126(77.30%) cases in fish handler group (a) and 27(37.5%) cases in the control group (b). Seropositive cases were observed more among the higher age group (>40 years) than in lower age group (<40 years) which was 86% and 67% respectively. Endoscopic examination was done among the seropositive cases having positive PUD features. Total seropositive cases were 153 and among them 81 have positive PUD features, among them 48 cases were selected for endoscopic examination. Among the fish handlers out of 34 cases, 31(91.17%) were RUT positive and out of 14 non-fish handlers 6(42.85%) were RUT positive. Among the fish handlers, 28(82.35%) of the 34-biopsy specimens were H & E positive and among the non-fish handlers, out of 14 samples, 5(35.71%) were H & E positive. Fish handlers have more association of H. Pylori infection than non fish handlers and higher age group persons are more prone to H. Pylori infection. A significant number of seropositive persons have association with positive RUT and H & E staining report.

Clinical Profile of Low Vision Patients Attending in Low Vision Clinic in a Tertiary Care Hospital.

The purpose of the study was to determine the disease profile of patients attending the low vision clinic of a tertiary eye care hospital at National Institute of Ophthalmology & Hospital (NIO&H), Dhaka, Bangladesh July 2016 to June 2017. Low vision and blindness are major causes of morbidity and an economic burden on the individual, family and the country. Low vision service has emerged as a major challenge faced by the developing countries .so prompt diagnosis; early treatment and early use of low vision devices can improve the quality of life. It was a prospective observational study conducted in low vision clinic at a tertiary care hospital in Bangladesh for one year. A total 419 patient, aged 6-60 years among them 267(63.7%) were male and 152(36.3%) were female. The leading causes of low vision in patient attending the low vision clinic were Retinitis pigmentosa (31.3%) macular dystrophy/stargards diseases & maculopathy (20.3%) and myopia with macular degeneration (14.8%). The percentage of visual impaired (6/18-6/60) were 38.3%, severely visual impaired (<6/60-3/60) were 24.4% & (<3/60) 37.3%. Almost all the patient was prescribed spectacles and Telescope for distant vision, Hand held magnifier and video magnifier were prescribed for near vision. Vision improved with low vision devices (6/18 or better) in 49.5%, (6/18-6/60) in 47.3%, (<6/60-3/60) in 2.8%, (<3/60) in 0.3% patient. Vision with low vision devices were significantly changes (p=0.001). The present study shows that hereditary ocular anomalies (Retinitis pigmentosa, macular dystrophy, myopic degeneration) and amblyopia were more common causes of low vision in this part of world.

Physical detection of heteroduplexes during meiotic recombination in the yeast Saccharomyces cerevisiae.

We describe a general physical method for detecting the heteroduplex DNA that is formed as an intermediate in meiotic recombination in the yeast Saccharomyces cerevisiae. We use this method to study the kinetic relationship between the formation of heteroduplex DNA and other meiotic events. We show that strains with the rad50, but not the rad52, mutation are defective in heteroduplex formation. We also demonstrate that, although cruciform structures can be formed in vivo as a consequence of heteroduplex formation between DNA strands that contain different palindromic insertions, small palindromic sequences in homoduplex DNA are rarely extruded into the cruciform conformation.

Long palindromic sequences induce double-strand breaks during meiosis in yeast.

Inverted-repeated or palindromic sequences have been found to occur in both prokaryotic and eukaryotic genomes. Such repeated sequences are usually short and present at several functionally important regions in the genome. However, long palindromic sequences are rare and are a major source of genomic instability. The palindrome-mediated genomic instability is believed to be due to cruciform or hairpin formation and subsequent cleavage of this structure by structure-specific nucleases. Here we present both genetic and physical evidence that long palindromic sequences (>50 bp) generate double-strand breaks (DSBs) at a high frequency during meiosis in the yeast Saccharomyces cerevisiae. The palindrome-mediated DSB formation depends on the primary sequence of the inverted repeat and the location and length of the repeated units. The DSB formation at the palindrome requires all of the gene products that are known to be responsible for DSB formation at the normal meiosis-specific sites. Since DSBs are initiators of nearly all meiotic recombination events, most of the palindrome-induced breaks appear to be repaired by homologous recombination. Our results suggest that short palindromic sequences are highly stable in vivo. In contrast, long palindromic sequences make the genome unstable by inducing DSBs and such sequences are usually removed from the genome by homologous recombination events.

Meiotic recombination between dispersed repeated genes is associated with heteroduplex formation.

In Saccharomyces cerevisiae, recombination events occurring between allelic genes located on homologous chromosomes are often associated with heteroduplex formation. We found that recombination events between repeated genes on nonhomologous chromosomes (ectopic events) are also associated with the formation of heteroduplexes, indicating that classical and ectopic recombination events involve similar mechanisms.

SSP1, a gene necessary for proper completion of meiotic divisions and spore formation in Saccharomyces cerevisiae.

During meiosis, a diploid cell undergoes two rounds of nuclear division following one round of DNA replication to produce four haploid gametes. In yeast, haploid meiotic products are packaged into spores. To gain new insights into meiotic development and spore formation, we followed differential expression of genes in meiotic versus vegetatively growing cells in the yeast Saccharomyces cerevisiae. Our results indicate that there are at least five different classes of transcripts representing genes expressed at different stages of the sporulation program. Here we describe one of these differentially expressed genes, SSP1, which plays an essential role in meiosis and spore formation. SSP1 is expressed midway through meiosis, and homozygous ssp1 diploid cells fail to sporulate. In the ssp1 mutant, meiotic recombination is normal but viability declines rapidly. Both meiotic divisions occur at the normal time; however, the fraction of cells completing meiosis is significantly reduced, and nuclei become fragmented soon after meiosis II. The ssp1 defect does not appear to be related to a microtubule-cytoskeletal-dependent event and is independent of two rounds of chromosome segregation. The data suggest that Ssp1 is likely to function in a pathway that controls meiotic nuclear divisions and coordinates meiosis and spore formation.

A 140-bp-long palindromic sequence induces double-strand breaks during meiosis in the yeast Saccharomyces cerevisiae.

Palindromic sequences have the potential to form hairpin or cruciform structures, which are putative substrates for several nucleases and mismatch repair enzymes. A genetic method was developed to detect such structures in vivo in the yeast Saccharomyces cerevisiae. Using this method we previously showed that short hairpin structures are poorly repaired by the mismatch repair system in S. cerevisiae. We show here that mismatches, when present in the stem of the hairpin structure, are not processed by the repair machinery, suggesting that they are treated differently than those in the interstrand base-paired duplex DNA. A 140-bp-long palindromic sequence, on the contrary, acts as a meiotic recombination hotspot by generating a site for a double-strand break, an initiator of meiotic recombination. We suggest that long palindromic sequences undergo cruciform extrusion more readily than short ones. This cruciform structure then acts as a substrate for structure-specific nucleases resulting in the formation of a double-strand break during meiosis in yeast. In addition, we show that residual repair of the short hairpin structure occurs in an MSH2-independent pathway.

Seven-base-pair inverted repeats in DNA form stable hairpins in vivo in Saccharomyces cerevisiae.

Palindromic sequences in single-stranded DNA and RNA have the potential for intrastrand base pairing, resulting in formation of "hairpin" structures. We previously reported a genetic method for detecting such structures in vivo in the yeast Saccharomyces cerevisiae. Below, we describe evidence indicating that a 14-base-pair palindrome (7 bp per inverted repeat) is sufficient for formation of a hairpin in vivo.

Genetic evidence for preferential strand transfer during meiotic recombination in yeast.

During meiotic recombination in the yeast Saccharomyces cerevisiae, heteroduplexes are formed as an intermediate in the exchange process. In the formation of an asymmetric heteroduplex, one chromosome acts as a donor of a single DNA strand and the other acts as a recipient. We present genetic evidence that the nontranscribed strand is donated more frequently than the transcribed strand in spores that have an unrepaired mismatch at the HIS4 locus.

Heteroduplex DNA formation and homolog pairing in yeast meiotic mutants.

Previous studies of Saccharomyces cerevisiae have identified several meiosis-specific genes whose products are required for wild-type levels of meiotic recombination and for normal synaptonemal complex (SC) formation. Several of these mutants were examined in a physical assay designed to detect heteroduplex DNA (hDNA) intermediates in meiotic recombination. hDNA was not detected in the rec102, mei4 and hop1 mutants; it was observed at reduced levels in red1, mek1 and mer1 strains and at greater than the wild-type level in zip1. These results indicate that the REC102, MEI4, HOP1, RED1, MEK1 and MER1 gene products act before hDNA formation in the meiotic recombination pathway, whereas ZIP1 acts later. The same mutants assayed for hDNA formation were monitored for meiotic chromosome pairing by in situ hybridization of chromosome-specific DNA probes to spread meiotic nuclei. Homolog pairing occurs at wild-type levels in the zip1 and mek1 mutants, but is substantially reduced in mei4, rec102, hop1, red1 and mer1 strains. Even mutants that fail to recombine or to make any SC or SC precursors undergo a significant amount of meiotic chromosome pairing. The in situ hybridization procedure revealed defects in meiotic chromatin condensation in mer1, red1 and hop1 strains.

Isolation of NDM-1-producing multidrug-resistant Pseudomonas putida from a paediatric case of acute gastroenteritis, India.

Pseudomonas putida is an uncommon opportunistic pathogen, usually susceptible to antimicrobial agents. Data concerning resistance to antimicrobial agents in clinical P. putida isolates are limited. To the best of our knowledge we report for the first time the isolation of NDM-1-producing multidrug-resistant P. putida from a case of acute gastroenteritis. The isolate showed resistance to a wide range of antimicrobials, including fluoroquinolones, third-generation cephalosporins and carbapenems. The isolate also exhibited multiple mutations in the quinolone resistance determining region and showed the presence of qepA, bla TEM , bla OXA1 and bla OXA7 genes. The present study highlights the importance of looking for the relatively rare aetiological agents in clinical samples that do not yield common pathogens.

IS50-mediated inverse transposition: specificity and precision.

The IS50 elements, which are present as inverted repeats in the kanamycin-resistance transposon, Tn5, can move in unison carrying with them any interstitial DNA segment. In consequence, DNA molecules such as a lambda::Tn5 phage genome are composed of two overlapping transposons - the kan segment bracketed by IS50 elements (Tn5), and lambda bracketed by IS50 elements. During direct transposition, mediated by IS50 "O" (outside) ends, the kan gene is moved and the lambda vector is left behind. During inverse transposition, mediated by the "I" (inside) ends of the IS50 elements, the lambda vector segment is moved and the kan gene is left behind. Direct transposition is several orders of magnitude more frequent than inverse transposition (Isberg and Syvanen, 1981; Sasakawa and Berg, 1982). We assessed the specificity and precision of the rare events mediated by pairs of I ends by mapping and sequencing independent inverse transpositions from a lambda::Tn5 phage into the amp and tet genes of plasmid pBR322. Using restriction analyses, 32 and 40 distinct sites of insertion were found among 46 and 72 independent inverse transpositions into the amp and tet genes, respectively. Eleven sites were used in two or more insertion events, and the two sites in tet used most frequently corresponded to major hotspots for the insertion of the Tn5 (by direct transposition). The sequences of 22 sites of inverse transposition (including each of the sites used more than once) were determined, in eleven cases by analyzing both pBR322-IS50 junctions, and in eleven others by sequencing one junction. The sequence of the "I" end of IS50 was preserved and 9-bp target sequence duplications were present in every case analyzed. GC pairs were found at each end of the target sequence duplication in ten of the eleven sites used more than once, and also in seven of the other eleven sites. Our data indicate that transposition mediated by pairs of "I" ends is similar in its specificity and precision to the more frequent transposition mediated by IS50 "O" ends.

Bidirectional chain-termination nucleotide sequencing: transposon Tn5seq1 as a mobile source of primer sites.

The sequencing of large DNA fragments by the chain-termination method [Sanger et al., Proc. Natl. Acad. Sci. USA 74 (1977) 5463-5467] has generally required extensive manipulations to bring all parts of the fragment near a specific primer-binding site, or the repeated synthesis of new oligodeoxynucleotide primers. Here we develop a more efficient approach, the use of a transposable element to insert primer binding sites at random in the DNA of interest. We constructed a Tn5 derivative called Tn5seq1 with unique DNA segments near each end so that oligodeoxynucleotides matching them could serve as primers for sequencing in each direction from any Tn5seq1 insertion site. Our experiments demonstrate the use of Tn5seq1 for sequencing in pBR322 plasmids and also in uncloned DNAs of the Escherichia coli chromosome. The unique segments near the left and right ends of Tn5seq1 are promoters from phages T7 and SP6, respectively, to permit the efficient transcription of adjacent DNAs in vivo or in vitro.

Nitrite content and antioxidant enzyme levels in the blood of schizophrenia patients.

RATIONALE: Recent studies have suggested augmentation in the inflammatory response as well as involvement of nitric oxide (NO) in mood disorders. Polymorphonuclear leukocytes (PMN), NO and free radicals have been associated with inflammatory response; however, the status of NO in the PMN has not been investigated so far in schizophrenia patients. OBJECTIVES: The present study was undertaken to investigate levels of nitrite (a metabolite of NO), malonaldehyde (MDA, lipid peroxidation product) and antioxidant enzymes such as superoxide dismutase (SOD), catalase and glutathione peroxidase (Gpx) in the PMN of schizophrenia patients. METHODS: Patients with schizophrenia (n=62) were diagnosed according to DSM-IV and were free of anti-psychotic medications/ECT for at least 3 months. Mean age of the patients was 29.06+/-1.17 years, with a male to female ratio of 4:1, and mean duration of illness was 3.7+/-0.6 years. The control group consisted of 82 healthy subjects with a mean age of 37.0+/-1.26 and a male to female ratio of 5:1. PMN were isolated from the blood. Nitrite, MDA and antioxidant enzymes were estimated by standard biochemical techniques in the PMN of normal healthy controls and schizophrenia patients. Platelet and plasma nitrite levels were also estimated in controls and schizophrenia patients. RESULTS: Nitrite content in the PMN was reduced to 68%, while plasma and platelet nitrite content in schizophrenia patients was not significantly changed in comparison to controls. Malonaldehyde (MDA) content in PMN was significantly augmented in schizophrenia patients but activity of SOD, catalase and Gpx remain unaltered. CONCLUSION: Results obtained indicate a significant decrease in NO synthesis and an increase in MDA in the PMN of schizophrenia patients, while antioxidant enzyme activities were not altered in the PMN of schizophrenia patients. This suggests that the decrease in PMN NO synthesis by PMN might lead to oxidative stress in schizophrenia patients.

A study on nitric oxide, beta-adrenergic receptors and antioxidant status in the polymorphonuclear leukocytes from the patients of depression.

BACKGROUND: alterations in the polymorphonuclear leukocyte (PMNs) receptors, second messenger system and in their responses have been found associated with depression. Recently role of tetrahydrobiopterin and nitric oxide has also been reported in the depressive disorders. It was therefore considered worthwhile to investigate the NOS activity in the PMNs, which like neurons, also express neuronal NOS (nNOS), antioxidant enzyme levels [superoxide dismutase (SOD), catalase and glutathione peroxidase (Gpx)] and beta-adrenergic receptors in the patients of depression. METHODS: patients were diagnosed according to the DSM-IV and were medication free, while healthy age-matched controls were also included in the study to estimate nitrite content, beta-adrenergic receptors and antioxidant enzymes in the PMNs according to the standard methodologies. RESULTS: an analysis of 66 cases of depression and 114 controls revealed 73% decrease in nitrite content and 71% decrease in beta-adrenergic receptor binding in the patients as compared to the healthy controls. However, activities of SOD, catalase and Gpx were not significantly altered in the patients. CONCLUSION: the results of the present study for the first time indicate alterations the NOS activity in PMNs obtained form the patients of affective disorders.

Antioxidant levels in the rat brain after nitric oxide synthase inhibition: a preliminary report.

Protective effects of NOS inhibitors and free radical scavengers in cerebral ischemia are well documented. The present study was undertaken to determine the possible effects of NOS inhibition on brain antioxidants. Levels of both enzymatic [glutathione peroxidase (GPx), catalase and superoxide dismutase (SOD)] and non-enzymatic [reduced glutathione (GSH)] antioxidants following nitric oxide synthase (NOS) inhibition by N(G)-nitro-L-arginine methyl ester (L-NAME), D-NAME or 7-nitroindazole (7-NI) have been investigated. NOS activity and antioxidant levels in the rat cerebellum and medulla were estimated 1 h after treatment with L-NAME (10, 30 and 100 mg/kg, i.p.), D-NAME (100 mg/kg, i.p.) or 7-NI (25 mg/kg, i.p.). L-NAME and 7-NI inhibited NOS activity in a dose-dependent manner. D-NAME also exhibited significant NOS inhibition. The activity of SOD and the GSH level remained unaltered following NOS inhibition. However, L-NAME and D-NAME at 100 mg/kg attenuated GPx activity in the cerebellum, though 7-NI had no effect. L-NAME inhibited catalase activity in medulla only at 30 mg/kg, but had no effect in cerebellum. However, 7-NI (25 mg/kg), D-NAME and L-NAME at 100 mg/kg did not affect catalase activity in the rat brain. Thus, NOS inhibition by the three agents did not have major effects on brain antioxidant levels.