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The teeth are the most challenging material to work with in the human body. Existing methods for detecting teeth problems are characterised by low efficiency, the complexity of the experiential operation, and a higher level of user intervention. Older oral disease detection approaches were manual, time-consuming, and required a dentist to examine and evaluate the disease. To address these concerns, we propose a novel approach for detecting and classifying the four most common teeth problems: cavities, root canals, dental crowns, and broken-down root canals, based on the deep learning model. In this study, we apply the YOLOv3 deep learning model to develop an automated tool capable of diagnosing and classifying dental abnormalities, such as dental panoramic X-ray images (OPG). Due to the lack of dental disease datasets, we created the Dental X-rays dataset to detect and classify these diseases. The size of datasets used after augmentation was 1200 images. The dataset comprises dental panoramic images with dental disorders such as cavities, root canals, BDR, dental crowns, and so on. The dataset was divided into 70% training and 30% testing images. The trained model YOLOv3 was evaluated on test images after training. The experiments demonstrated that the proposed model achieved 99.33% accuracy and performed better than the existing state-of-the-art models in terms of accuracy and universality if we used our datasets on other models.

Chemotaxis towards nutrients plays a crucial role in root colonization by Pseudomonas fluorescens. The P. fluorescens chemotactic transducer of amino acids type A (CtaA) mediates movement towards amino acids present in root exudates. In this study, the periplasmic sensory domain of CtaA has been crystallized by the hanging-drop vapor diffusion method using ammonium sulfate as a precipitating agent. A complete data set was collected to 1.9 Å resolution using cryocooling conditions and synchrotron radiation. The crystals belong to space group I222 or I212121, with unit-cell parameters a = 67.2, b = 76.0, c = 113.3 Å. This is an important step towards elucidation of the structural basis of how CtaA recognizes its signal molecules and transduces the signal across the membrane.

General control non-repressible 5 (GCN5)-related N-acetyltransferases (GNAT) catalyze the transfer of an acyl moiety from acyl coenzyme A (acyl-CoA) to a diverse group of substrates and are widely distributed in all domains of life. This review of the currently available data acquired on GNAT enzymes by a combination of structural, mutagenesis and kinetic methods summarizes the key similarities and differences between several distinctly different families within the GNAT superfamily, with an emphasis on the mechanistic insights obtained from the analysis of the complexes with substrates or inhibitors. It discusses the structural basis for the common acetyltransferase mechanism, outlines the factors important for the substrate recognition, and describes the mechanism of action of inhibitors of these enzymes. It is anticipated that understanding of the structural basis behind the reaction and substrate specificity of the enzymes from this superfamily can be exploited in the development of novel therapeutics to treat human diseases and combat emerging multidrug-resistant microbial infections.

Flagella-mediated motility and chemotaxis towards nutrients are important characteristics of Vibrio fischeri that play a crucial role in the development of its symbiotic relationship with its Hawaiian squid host Euprymna scolopes. The V. fischeri chemoreceptor A (VfcA) mediates chemotaxis toward amino acids. The periplasmic sensory domain of VfcA has been crystallized by the hanging-drop vapour-diffusion method using polyethylene glycol 3350 as a precipitating agent. The crystals belonged to space group P1, with unit-cell parameters a = 39.9, b = 57.0, c = 117.0 Å, α = 88.9, β = 80.5, γ = 89.7°. A complete X-ray diffraction data set has been collected to 1.8 Å resolution using cryocooling conditions and synchrotron radiation.

Helicobacter pylori infection is the common cause of gastroduodenal diseases linked to a higher risk of the development of gastric cancer. Persistent infection requires functional flagella that are heavily glycosylated with 5,7-diacetamido-3,5,7,9-tetradeoxy-L-glycero-L-manno-nonulosonic acid (pseudaminic acid). Pseudaminic acid biosynthesis protein H (PseH) catalyzes the third step in its biosynthetic pathway, producing UDP-2,4-diacetamido-2,4,6-trideoxy-β-L-altropyranose. It belongs to the GCN5-related N-acetyltransferase (GNAT) superfamily. The crystal structure of the PseH complex with cofactor acetyl-CoA has been determined at 2.3 Å resolution. This is the first crystal structure of the GNAT superfamily member with specificity to UDP-4-amino-4,6-dideoxy-β-L-AltNAc. PseH is a homodimer in the crystal, each subunit of which has a central twisted β-sheet flanked by five α-helices and is structurally homologous to those of other GNAT superfamily enzymes. Interestingly, PseH is more similar to the GNAT enzymes that utilize amino acid sulfamoyl adenosine or protein as a substrate than a different GNAT-superfamily bacterial nucleotide-sugar N-acetyltransferase of the known structure, WecD. Analysis of the complex of PseH with acetyl-CoA revealed the location of the cofactor-binding site between the splayed strands β4 and β5. The structure of PseH, together with the conservation of the active-site general acid among GNAT superfamily transferases, are consistent with a common catalytic mechanism for this enzyme that involves direct acetyl transfer from AcCoA without an acetylated enzyme intermediate. Based on structural homology with microcin C7 acetyltransferase MccE and WecD, the Michaelis complex can be modeled. The model suggests that the nucleotide- and 4-amino-4,6-dideoxy-β-L-AltNAc-binding pockets form extensive interactions with the substrate and are thus the most significant determinants of substrate specificity. A hydrophobic pocket accommodating the 6'-methyl group of the altrose dictates preference to the methyl over the hydroxyl group and thus to contributes to substrate specificity of PseH.

Helicobacter pylori infection is the common cause of gastritis and duodenal and stomach ulcers, which have been linked to a higher risk of the development of gastric cancer. The motility that facilitates persistent infection requires functional flagella that are heavily glycosylated with 5,7-diacetamido-3,5,7,9-tetradeoxy-L-glycero-L-manno-nonulosonic acid (pseudaminic acid). Pseudaminic acid biosynthesis protein H (PseH) catalyzes the third step in its biosynthetic pathway, producing UDP-2,4-diacetamido-2,4,6-trideoxy-β-L-altropyranose. Crystals of H. pylori PseH have been grown by the hanging-drop vapour-diffusion method using diammonium tartrate as a precipitating agent. The crystals belonged to space group I222 or I212121, with unit-cell parameters a = 107.8, b = 145.4, c = 166.3 Å. A complete X-ray diffraction data set has been collected to 2.5 Å resolution using cryocooling conditions and synchrotron radiation.

Salmonellosis, an acute invasive enteric infection, is endemic in Bangladesh. We analyzed 128,312 stool samples of diarrheal patients to identify Salmonella spp. during 2005-2013. A total of 2120 (1.7%) Salmonella spp. were isolated and the prevalence of Salmonella spp. decreased significantly over time (2→1%, P < 0.001). Among the typhoidal Salmonella (TS) serogroups, S. Typhi was predominant (404, [65.1%]) followed by S. Paratyphi B (139, [22.4%]) and S. Paratyphi A (78, [12.6%]). Of the nontyphoidal Salmonella (NTS) isolates, the serogroup C1 (560, [37%]) was predominant followed by B (379, [25%]), C2 (203, [14%]), E (127, [9%]), and D (94, [6%]). Most of the resistance was found towards nalidixic acid (40%), ampicillin (36%), cotrimoxazole (20%), chloramphenicol (13%), ciprofloxacin (4%), and ceftriaxone (4%). Interestingly, 32% of the isolates showed reduced susceptibility to Cip. Multiantibiotic resistance (MAR, ≥3 drugs) was more common among TS than NTS strains (P < 0.001). Among the representative ceftriaxone-resistant isolates, bla TEM gene was detected among 88% (7/8) of the strains, whereas only one strain of S. Typhi was positive for both bla TEM and bla CTX-M genes. The study reflects higher prevalence of MAR Salmonella spp. and is the first to report the bla TEM gene mediated ESBL production among Salmonellae in Bangladesh. Emergence of MAR Salmonella spp. in particular ESBL strains should be considered a public health concern.

We determined the frequency of multidrug resistant (MDR) infections with Shigella spp. and Vibrio cholerae O1 at an urban (Dhaka) and rural (Matlab) hospital in Bangladesh. We also compared sociodemographic and clinical features of patients with MDR infections to those with antibiotic-susceptible infections at both sites. Analyses were conducted using surveillance data from the International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), for the years 2000-2012. Compared to patients with antibiotic-susceptible for Shigella infections, those in Dhaka with MDR shigellosis were more likely to experience diarrhea for >24 hours, while, in Matlab, they were more likely to stay inhospital >24 hours. For MDR shigellosis, Dhaka patients were more likely than those in Matlab to have dehydration, stool frequency >10/day, and diarrheal duration >24 hours. Patients with MDR Vibrio cholerae O1 infections in Dhaka were more likely than those in Matlab to experience dehydration and stool frequency >10/day. Thus, patients with MDR shigellosis and Vibrio cholerae O1 infection exhibited features suggesting more severe illness than those with antibiotic-susceptible infections. Moreover, Dhaka patients with MDR shigellosis and Vibrio cholerae O1 infections exhibited features indicating more severe illness than patients in Matlab.

Shigellosis, caused by Shigella species, is a major public health problem in Bangladesh. To determine the prevalence and distribution of different Shigella species, we analyzed 10,827 Shigella isolates from patients between 2001 and 2011. S. flexneri was the predominant species isolated throughout the period. However, the prevalence of S. flexneri decreased from 65.7% in 2001 to 47% in 2011, whereas the prevalence of S. sonnei increased from 7.2% in 2001 to 25% in 2011. S. boydii and S. dysenteriae accounted for 17.3% and 7.7% of the isolates respectively throughout the period. Of 200 randomly selected S. sonnei isolates for extensive characterization, biotype g strains were predominant (95%) followed by biotype a (5%). Resistance to commonly used antibiotics including trimethoprim-sulfamethoxazole, nalidixic acid, ciprofloxacin, mecillinam and ampicillin was 89.5%, 86.5%, 17%, 10.5%, and 9.5%, respectively. All isolates were susceptible to ceftriaxone, cefotaxime, ceftazidime and imipenem. Ninety-eight percent of the strains had integrons belonging to class 1, 2 or both. The class 1 integron contained only dfrA5 gene, whereas among class 2 integron, 16% contained dhfrAI-sat1-aadA1-orfX gene cassettes and 84% harbored dhfrA1-sat2 gene cassettes. Plasmids of ∼5, ∼1.8 and ∼1.4 MDa in size were found in 92% of the strains, whereas only 33% of the strains carried the 120 MDa plasmid. PFGE analysis showed that strains having different integron patterns belonged to different clusters. These results show a changing trend in the prevalence of Shigella species with the emergence of multidrug resistant S. sonnei. Although S. flexneri continues to be the predominant species albeit with reduced prevalence, S. sonnei has emerged as the second most prevalent species replacing the earlier dominance by S. boydii and S. dysenteriae in Bangladesh.

Enteric pathogens are commonly associated with diarrhea among malnourished children. This study aimed to determine the association between the severity of diarrheal illnesses and malnutrition among under 5-year-old children. During 2010 and 2011, we studied 2,324 under 5-year-old diarrheal children with mild disease (MD) and moderate-to-severe disease (MSD) attending a hospital in Bangladesh. Children with MSD were more likely to be malnourished compared with children with MD (35% versus 24%, P < 0.001). In multivariate analysis, malnutrition (odds ratio [95% confidence interval] = 1.53 [1.22, 1.92]), age of the child (24-59 months; 1.67 [1.28, 2.19]), fever (1.65 [1.28, 2.12]), abdominal pain (1.87 [1.48, 2.37]), straining (5.93 [4.80, 7.33]), and infection with Shigella (3.26 [2.38, 4.46]) and Vibrio cholerae (2.21 [1.07, 4.58]) were shown to be significantly associated with MSD. Factors significantly associated with malnutrition were disease severity (1.56 [1.24, 1.95]), age (24-59 months; 1.75 [1.38, 2.22]), mother's schooling (1.54 [1.16, 2.04]), and monthly household income (1.71 [1.42, 2.07]). Childhood malnutrition was associated with dysentery and dehydrating diarrhea.