Hexafluoroisopropanol as a Bioconjugation Medium of Ultrafast, Tryptophan-Selective Catalysis

The past decade has seen a remarkable growth in the number of bioconjugation techniques in chemistry, biology, material science, and biomedical fields. A core design element in bioconjugation technology is a chemical reaction that can form a covalent bond between the protein of interest and the labeling reagent. Achieving chemoselective protein bioconjugation in aqueous media is challenging, especially for generally less reactive amino acid residues, such as tryptophan. We present here the development of tryptophan-selective bioconjugation methods through ultrafast Lewis acid-catalyzed reactions in hexafluoroisopropanol (HFIP). Structure-reactivity relationship studies have revealed a combination of thiophene and ethanol moieties to give a suitable labeling reagent for this bioconjugation process, which enables modification of peptides and proteins in an extremely rapid reaction unencumbered by noticeable side reactions. The capability of the labeling method also facilitated radiofluorination application as well as antibody functionalization. Enhancement of an α-helix by HFIP leads to its compatibility with a certain protein, and this report also demonstrates a further stabilization strategy achieved by the addition of an ionic liquid to the HFIP medium. The nonaqueous bioconjugation approaches allow access to numerous chemical reactions that are unavailable in traditional aqueous processes and will further advance the chemistry of proteins.

Draft genome sequence of multidrug-resistant Citrobacter portucalensis BAU_133-2 strain isolated from a domestic duck (Anas platyrhynchos domesticus) in Bangladesh

We announce the genome sequence of the Citrobacter portucalensis BAU_133-2 strain isolated from a domestic duck. Our assembled genome contained a length of 4.8 Mb, 110.0× genome coverage, 51.91% of an average GC content, 1 plasmid, 1 CRISPR array, 8 prophages, 27 antibiotic resistance genes, and 75 virulence factor genes.

Draft Genome Sequence of the Multidrug-Resistant Citrobacter freundii 132-2 Strain Isolated from a Domestic Duck in Bangladesh

We sequenced a multidrug-resistant strain of Citrobacter freundii, 132-2, isolated from a cloacal swab sample of a domestic duck. The whole genome of the C. freundii 132-2 strain had a length of 5,097,592 bp, 62 contigs, two plasmids, and an average G+C content of 51.85%, with a 105.0× genome coverage.

Phenotypic and Genotypic Characteristics of Antimicrobial Resistance in Citrobacter freundii Isolated from Domestic Ducks (Anas platyrhynchos domesticus) in Bangladesh

Antimicrobial resistance (AMR) in Citrobacter freundii poses a serious challenge as this species is one of the sources of nosocomial infection and causes diarrheal infections in humans. Ducks could be the potential source of multidrug-resistant (MDR) C. freundii; however, AMR profiles in C. freundii from non-human sources in Bangladesh have remained elusive. This study aimed to detect C. freundii in domestic ducks (Anas platyrhynchos domesticus) in Bangladesh and to determine their phenotypic and genotypic antibiotic susceptibility patterns. A total of 150 cloacal swabs of diseased domestic ducks were screened using culturing, staining, biochemical, polymerase chain reaction (PCR), and matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) to detect C. freundii. Phenotypic and genotypic antibiotic susceptibility patterns were done by the disk diffusion method and PCR, respectively. In total, 16.67% (25/150) of the samples were positive for C. freundii. C. freundii isolates showed a range of 20% to 96% resistance to cefotaxime, gentamicin, levofloxacin, ciprofloxacin, cotrimoxazole, tetracycline, ampicillin, and cephalexin. More than 60% of the isolates were phenotypically MDR, and the index of multiple antibiotic resistance ranged from 0.07 to 0.79. Genes encoding resistance to beta-lactams [bla_TEM-1-88% (22/25), bla_CMY-2-56% (14/25), bla_CMY-9-8% (2/25), and bla_CTX-M-14-20% (5/25)], sulfonamides [sul1-52% (13/25), sul2-24% (6/25)], tetracyclines [tetA-32% (8/25) and tetB-4% (1/25)], aminoglycosides [aacC4-16% (4/25)], and fluoroquinolones [qnrA-4% (1/25), qnrB-12% (3/25), and qnrS-4% (1/25)] were detected in the isolated C. freundii. To the best of our knowledge, this is the first study in Bangladesh to detect MDR C. freundii with their associated resistance genes from duck samples. We suggest addressing the burden of diseases in ducks and humans and associated AMR issues using the One Health approach.

Psychological Assessment of Health-Care Workers Working during COVID-19 Pandemic Condition in Bangladesh

The study was aimed to assess the psychological aspects and relevant factors of the health-care workers (HCWs) working in COVID 19 pandemic condition in Bangladesh. This online cross-sectional survey was conducted from different tertiary, secondary and primary hospitals in Bangladesh. Eligible 638 HCWs who were directly involved in the caring of confirmed or suspected COVID-19 patients were recruited in this study. The mental health was assessed by the Patient Health Questionnare-9 (PHQ-9), Generalized Anxiety Disorder-7 (GAD-7) and Athens Insomnia Scale (AIS). High frequency of depression 536(84.0%), anxiety 386(60.5%) and insomnia 302(47.3%) was found among the HCWs, which were significantly higher in physicians (p<0.001) than nurses. Moderate to severe depression was significantly higher in female, whereas minimal to mild depression was significant in male HCWs (p=0.014). Symptoms of depression (p<0.001), anxiety (p<0.001) and insomnia (p=0.004) were significantly higher among the HCWs of primary and secondary compared to the tertiary level. The HCWs developed psychological trauma due to family health (45.3%) and contagious disease property (66.6%). After adjusting confounders, multivariable logistic regression analysis showed that physicians and HCWs of secondary hospital had significant symptoms of severe depression (OR=2.95, 95% CI=0.50-17.24; p<0.001), anxiety (OR=2.64, 95% CI=0.80-8.72; p<0.001) and insomnia (OR=2.67, 95% CI=1.23-5.84; p=0.018); whereas female HCWs had more risk of developing symptoms of severe insomnia (OR= 1.84; 95% CI=1.23-2.75; p=0.003). High rate of depression, anxiety and insomnia was found among HCWs working in the COVID-19 pandemic condition in this survey.

Probiotics, prebiotics and synbiotics improved the functionality of aquafeed: Upgrading growth, reproduction, immunity and disease resistance in fish

Aquaculture plays an increasingly significant role in improving the sustainability of global fish production. This sector has been intensified with the advent of new husbandry practices and the development of new technology. However, the increasing intensification and indiscriminate commercialized farming has enhanced the vulnerability of cultivated aquatic species to damage from pathogens. In efforts to confront these various diseases, frequent use of drugs, antibiotics, chemotherapeutics, and agents for sterilization have unintentionally added to the risk of transmission of pathogens and harmful chemical compounds to consumers. Some natural dietary supplements are believed to have the potential to offset this setback in aquaculture. Application of bio-friendly feed additives such as probiotics, prebiotics and synbiotics are becoming popular dietary supplements with the potential to not only improve growth performance, but in some cases can also enhance immune competence and the overall well-being of fish and crustaceans. The present review discusses and summarizes the effects of probiotics, prebiotics and synbiotics application on growth, stress mitigation, microbial composition of intestine, immune system and health condition of aquatic animals in association with existing constraints and future perspectives in aquaculture.

Need Assessment for Updating the MBBS Curriculum 2012 of Bangladesh

Curriculum is the road map of any course and an instrument for developing the competencies of the human resources. The MBBS curriculum in our country was last updated in 2012 during the period of Millennium Development Goals (MDGs). Since then it has been under implementation in different government, non-government and Army medical colleges in association with different universities. "Health Professional for a New Century" now asks for a transformation of the education to strengthen the health systems for meeting the challenges of the 21st century. Curriculum reform is an important issue in transformative education and need assessment is the first and essential task to review and update any curriculum. The objective of the study was to assess the need to review and update the MBBS curriculum 2012 of Bangladesh. Review and updating of MBBS curriculum was organized by Centre for Medical Education (CME) and supported by World Health Organization (WHO). CME, DGHS, Dean offices, MOH&FW, BM&DC and all the government and non-government medical colleges were involved in this activity. Duration of study was 7 months from April 2019 to October 2019. Data were collected from academic councils of 102 medical colleges through structured questionnaire and through FGD with teachers and interns. Around 90(88.2%) academic councils agreed and 12(12%) disagreed about the appropriateness of existing four phases of MBBS curriculum. About 80(84.2%) academic councils agreed with 1.5 years duration of Phase I, 84(88.4%) agreed with one year duration of Phase II, 84(94.4%) agreed with one year duration of Phase III and 77(84.6%) agreed with 1.5 years duration of Phase IV. The study suggested the subjects for 2nd phase are, Pharmacology 74(84.1%), Pathology 53(60.3%), Forensic Medicine 46(52.3%), and for 3rd phase are Community Medicine 60(69.8%), Microbiology 54(62.8%). The study revealed that the subjects of overloaded contents are, Anatomy - 24(50%), Community Medicine - 35(72.9%) and Pathology - 19(39.6%). The study suggested incorporation of organized teaching-learning for behavioral science, communication skills, ethics and development of attitude by most of the academic councils. The study suggested that the increased duration of ambulatory care (outdoor/emergency) teaching. The study revealed around 84(83.2%) academic councils recommended that Single Best Answer (SBA) type of questions should be included in MCQ part for all subjects along with multiple true-false response and around 82(81.2%) academic councils recommended that Structured Essay Question (SEQ) should be included in written part along with Short Answer Question (SAQ). The study revealed that 58(58.6%) academic councils recommended that carry-on system should not be in Phase I and 53(53.5%) academic councils opined to introduce grading system in MBBS course. Most of the academic councils agreed about the appropriateness of existing four phases of MBBS curriculum. The subjects for 2nd phase are, Pharmacology - 84.1%, Pathology - 60.3%, Forensic Medicine - 52.3%, and for 3rd phase are Community Medicine - 69.8%, Microbiology - 62.8%. Most of the participants are in favour of the present curriculum components, grading system for assessment but not the carry-on system in Phase I. The study recommended for national level consultations involving the concerned persons for finalization of the MBBS curriculum.

Toward a Scalable and Sustainable Intervention for Complementary Food Safety

BACKGROUND

Contaminated complementary foods are associated with diarrhea and malnutrition among children aged 6 to 24 months. However, existing complementary food safety intervention models are likely not scalable and sustainable.

OBJECTIVE

To understand current behaviors, motivations for these behaviors, and the potential barriers to behavior change and to identify one or two simple actions that can address one or few food contamination pathways and have potential to be sustainably delivered to a larger population.

METHODS

Data were collected from 2 rural sites in Bangladesh through semistructured observations (12), video observations (12), in-depth interviews (18), and focus group discussions (3).

RESULTS

Although mothers report preparing dedicated foods for children, observations show that these are not separate from family foods. Children are regularly fed store-bought foods that are perceived to be bad for children. Mothers explained that long storage durations, summer temperatures, flies, animals, uncovered food, and unclean utensils are threats to food safety. Covering foods, storing foods on elevated surfaces, and reheating foods before consumption are methods believed to keep food safe. Locally made cabinet-like hardware is perceived to be acceptable solution to address reported food safety threats.

CONCLUSION

Conventional approaches that include teaching food safety and highlighting benefits such as reduced contamination may be a disincentive for rural mothers who need solutions for their physical environment. We propose extending existing beneficial behaviors by addressing local preferences of taste and convenience.

Visual enantiomeric recognition of amino acid derivatives in protic solvents

Various types of chiral host molecules 2-7 based on a phenolphthalein skeleton and two crown ethers were prepared for use in visual enantiomeric recognition, and we examined their enantioselective coloration in complexation with chiral amino acid derivatives 9-22 in methanol solution. Methyl-substituted host (S,S,S,S)-3 showed particularly prominent enantiomer selectivity for the alanine amide derivatives 11 and 12. A combination of methyl-substituted host (S,S,S,S)-3 with guest (R)-11 or (R)-12 developed a purple color, whereas no color development was observed with (S)-11 or (S)-12. On the other hand, phenyl-substituted host (S,S,S,S)-6 showed deeper coloration with a wide range of (S)-beta-amino alcohols compared to that seen with host (S,S,S,S)-6 and the corresponding (R)-beta-amino alcohols at 0 degrees C. Furthermore, absorbance inversion temperatures (AIT) were observed within the range of 0-50 degrees C in many cases.

Phosphorus uptake by grain legumes and subsequently grown wheat at different levels of residual phosphorus fertiliser

A considerable portion of the phosphorus (P) fertilisers applied in agriculture remains in the soil as sorbed P in the forms of various P compounds, termed residual P. Certain grain legume crops may be able to mobilise residual P through root exudates, and thus increase their own growth, and potentially that of subsequent cereal crops. The first objective of this pot experiment was to compare the growth and P uptake of 3 legume crop species with that of wheat grown in a soil with different levels of residual P. Another objective was to determine whether the influence of legumes on subsequent P uptake by wheat was due to legume-induced changes in the rhizosphere, or to the presence of legume roots. White lupin (Lupinus albus L.), field pea (Pisum sativum L.), faba bean (Vicia faba L.), and wheat (Triticum aestivum L.) were grown in a soil containing 25.7, 26.4, 30.8, 39.0, or 51.9 mg/kg of bicarbonate-extractable P and sufficient amounts of nitrogen to suppress nodulation and dinitrogen fixation. Differences among the species in root dry mass were much larger than those in shoot dry mass. Faba bean produced the greatest root dry mass. All the legumes exuded carboxylates from their roots, predominantly malate, at all soil P levels. Rhizosphere concentrations of carboxylates were highest for white lupin, followed by field pea and faba bean. All of the investigated legumes enhanced the growth of the subsequently grown wheat, compared with wheat grown after wheat, even at relatively high levels of soil P. The positive effect on growth was not dependent on the incorporation of the legume roots into the soil. The legumes also caused a modest increase in wheat shoot P concentrations, which were higher when roots were incorporated into the soil. Because of the increased growth and tissue P concentrations, wheat shoot P content was 30–50% higher when grown after legumes than when grown after wheat. The study concludes that the legume crops can enhance P uptake of subsequently grown wheat, even at relatively high levels of residual P.

Genetic basis of heterosis and inbreeding depression in rice (Oryza sativa L.)

The genetic basis of heterosis was studied through mid-parent, standard variety and better parent for 11 quantitative traits in 17 parental lines and their 10 selected hybrids in rice (Oryza sativa L.). The characters were plant height, days to flag leaf initiation, days to first panicle initiation, days to 100% flowering, panicle length, flag leaf length, days to maturity, number of fertile spikelet/panicle, number of effective tillers/hill, grain yield/10-hill, and 1000-grain weight. In general the hybrids performed significantly better than the respective parents. Significant heterosis was observed for most of the studied characters. Among the 10 hybrids, four hybrids viz., 17Ax45R, 25Ax37R, 27Ax39R, 31Ax47R, and 35Ax47R showed highest heterosis in 10-hill grain yield/10-hill. Inbreeding depression of F2 progeny was also studied for 11 characters of 10 hybrids. Both positive and negative inbreeding depression were found in many crosses for the studied characters, but none was found significant. Selection of good parents was found to be the most important for developing high yielding hybrid rice varieties.

Screening wheat genotypes for tolerance of soil acidity

A soil-based screening method was used to test tolerance of wheat genotypes to acidity. Plants were grown for 6 days in an acid soil with the pH adjusted to 3.9–5.8. The number and length of roots were measured. To validate the method, 12 wheat cultivars of known acidity tolerance and one acid-sensitive barley cultivar were grown on an acid soil in the field with or without amelioration of subsoil acidity. The relative yields of these wheat genotypes on the soil with subsoil acidity ranged from 50 to 89% of yields on soil without subsoil acidity, and were correlated with root growth parameters obtained in the glasshouse. The best correlation was obtained between relative yields in the field (y) and root length per plant (x) at pH 3.9 in the glasshouse (y = –43 + 52*log x, r = 0.95) or root length per plant at pH 3.9 as a percentage of root length at pH 4.8 (y = 1.2 + 46*log x, r = 0.94). Following validation of the glasshouse screening method in the field, 115 wheat genotypes, including cultivars and breeding lines, were screened in the glasshouse. A substantial genotypic variation in acidity tolerance was found, with root length per plant at pH 3.9 ranging from 66 to > 350 mm. Many Western Australian breeding lines displayed better tolerance than existing tolerant wheat cultivars. The screening system can be instrumental in breeding wheat for increased tolerance to acid soils.

Sequence-selective visual recognition of nonprotected dipeptides

[structure: see text] A receptor 1 with phenolphthalein and two crown ethers in the molecule develops brilliant purple color in the presence of dipeptides with a specific amino acid-sequence containing a C-terminal lysine. This type of color development could be extended to the detection of oligopeptides of a specific sequence at the N-terminal such as scyliorhinin I and APP(770)(394-410).

Visual enantiomeric recognition using chiral phenolphthalein derivatives

[structure: see text] Optically active artificial host molecules 2-5 based on a phenolphthalein skeleton have been prepared for visual enantiomeric recognition of alanine derivatives 8 and 9. The receptor 3 discriminates (R)-8 and (R)-9 from (S)-8 and (S)-9, respectively, to develop a purple color.

Visual recognition of triamines by phenolphthalein derivatives: consideration of the structure of the colored complex

[structure: see text] A hybrid molecule 1 consisting of phenolphthalein and two crown ether moieties can be used to discriminate the length of linear triamines strictly by color development. The purple color is developed most deeply at -10 degrees C and fades with either an increase or decrease in temperature.

Synthesis of extremely simplified compounds possessing the key pharmacophore units of taxol, phenylisoserine and oxetane moieties

Straight chain compounds having a phenylisoserine unit and an oxetane ring at the alpha- and omega- position, respectively as extremely simplified analogues of taxol were prepared. None of these compounds showed promising tubulin inhibitory activity.

Hepatitis induced by nomifensine

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Medical services without medical ethics: Sailing the ship without compass

doi: 10.3329/bjms.v8i1.3181Bangladesh Journal of Medical Science Vol.8 No. 1-2; 2009 4