MyMedR

Displaying publications 21 - 29 of 29 in total

Abstract:

Sort:

Fulltext 13C based proteinogenic amino acid (PAA) and metabolic flux ratio analysis of Lactococcus lactis reveals changes in pentose phosphate (PP) pathway in response to agitation and temperature related stresses

Azizan KA, Ressom HW, Mendoza ER, Baharum SN

PeerJ, 2017;5:e3451.
PMID: 28695065 DOI: 10.7717/peerj.3451

Lactococcus lactis subsp. cremoris MG1363 is an important starter culture for dairy fermentation. During industrial fermentations, L. lactis is constantly exposed to stresses that affect the growth and performance of the bacterium. Although the response of L. lactis to several stresses has been described, the adaptation mechanisms at the level of in vivo fluxes have seldom been described. To gain insights into cellular metabolism, 13C metabolic flux analysis and gas chromatography mass spectrometry (GC-MS) were used to measure the flux ratios of active pathways in the central metabolism of L. lactis when subjected to three conditions varying in temperature (30°C, 37°C) and agitation (with and without agitation at 150 rpm). Collectively, the concentrations of proteinogenic amino acids (PAAs) and free fatty acids (FAAs) were compared, and Pearson correlation analysis (r) was calculated to measure the pairwise relationship between PAAs. Branched chain and aromatic amino acids, threonine, serine, lysine and histidine were correlated strongly, suggesting changes in flux regulation in glycolysis, the pentose phosphate (PP) pathway, malic enzyme and anaplerotic reaction catalysed by pyruvate carboxylase (pycA). Flux ratio analysis revealed that glucose was mainly converted by glycolysis, highlighting the stability of L. lactis' central carbon metabolism despite different conditions. Higher flux ratios through oxaloacetate (OAA) from pyruvate (PYR) reaction in all conditions suggested the activation of pyruvate carboxylate (pycA) in L. lactis, in response to acid stress during exponential phase. Subsequently, more significant flux ratio differences were seen through the oxidative and non-oxidative pentose phosphate (PP) pathways, malic enzyme, and serine and C1 metabolism, suggesting NADPH requirements in response to environmental stimuli. These reactions could play an important role in optimization strategies for metabolic engineering in L. lactis. Overall, the integration of systematic analysis of amino acids and flux ratio analysis provides a systems-level understanding of how L. lactis regulates central metabolism under various conditions.

Matched MeSH terms: Carbon Isotopes
13C-Urea Breath Test Accuracy for Helicobacter pylori Infection in the Asian Population: A Meta-Analysis

Abd Rahim MA, Johani FH, Shah SA, Hassan MR, Abdul Manaf MR

Ann Glob Health, 2019 Jul 24;85(1).
PMID: 31348624

BACKGROUND: Helicobacter pylori (H. pylori) infection is known to be associated with peptic ulcer and gastric cancer. Detection of H. pylori infection is a significant part of peptic ulcer and gastric cancer prevention and management. 13C-urea breath test (UBT) provides a good option for the pathogen detection due to its accuracy and safety.
OBJECTIVE: This review aims to evaluate the 13C-UBT diagnostic accuracy studies conducted among Asian population and validate its use for the Asian population.
METHODS: Original articles were systematically searched in PubMed, Scopus, and Google Scholar using the PICOS strategy by applying relevant keywords. Only studies published in English and conducted in Asia were included. Our search returned 276 articles. After assessment, 11 articles which answered our research question and met the criteria set for systematic review and meta-analysis were accepted. A total of 15 study protocols were extracted from the 11 accepted articles.
FINDINGS: Majority of the studies were conducted in Hong Kong (six), followed by Taiwan (five), Japan (two), and one each in Singapore and Israel. All studies had used histology as part of its gold standard of reference. All but one study was performed on adult populations. The summary estimate for sensitivity was 97% (95% CI: 96, 98%), and specificity was 96% (95% CI: 95, 97%), with significant heterogeneity between studies. Adjusting for the dose (50 mg) and breath sample collection time (20 minutes) had improved both accuracy estimates and significantly reduced heterogeneity.
CONCLUSION: This review supports the test-and-treat strategy for H. pylori infection management. Prevalence and cost-effectiveness studies are mandatory for health authorities to adopt this strategy into national policy.

Matched MeSH terms: Carbon Isotopes
Fulltext Forest contraction in north equatorial Southeast Asia during the Last Glacial Period

Wurster CM, Bird MI, Bull ID, Creed F, Bryant C, Dungait JA, et al.

Proc Natl Acad Sci U S A, 2010 Aug 31;107(35):15508-11.
PMID: 20660748 DOI: 10.1073/pnas.1005507107

Today, insular Southeast Asia is important for both its remarkably rich biodiversity and globally significant roles in atmospheric and oceanic circulation. Despite the fundamental importance of environmental history for diversity and conservation, there is little primary evidence concerning the nature of vegetation in north equatorial Southeast Asia during the Last Glacial Period (LGP). As a result, even the general distribution of vegetation during the Last Glacial Maximum is debated. Here we show, using the stable carbon isotope composition of ancient cave guano profiles, that there was a substantial forest contraction during the LGP on both peninsular Malaysia and Palawan, while rainforest was maintained in northern Borneo. These results directly support rainforest "refugia" hypotheses and provide evidence that environmental barriers likely reduced genetic mixing between Borneo and Sumatra flora and fauna. Moreover, it sheds light on possible early human dispersal events.

Matched MeSH terms: Carbon Isotopes/metabolism
Fulltext Recent trends in the intrinsic water-use efficiency of ringless rainforest trees in Borneo

Loader NJ, Walsh RP, Robertson I, Bidin K, Ong RC, Reynolds G, et al.

Philos Trans R Soc Lond B Biol Sci, 2011 Nov 27;366(1582):3330-9.
PMID: 22006972 DOI: 10.1098/rstb.2011.0037

Stable carbon isotope (δ(13)C) series were developed from analysis of sequential radial wood increments from AD 1850 to AD 2009 for four mature primary rainforest trees from the Danum and Imbak areas of Sabah, Malaysia. The aseasonal equatorial climate meant that conventional dendrochronology was not possible as the tree species investigated do not exhibit clear annual rings or dateable growth bands. Chronology was established using radiocarbon dating to model age-growth relationships and date the carbon isotopic series from which the intrinsic water-use efficiency (IWUE) was calculated. The two Eusideroxylon zwageri trees from Imbak yielded ages of their pith/central wood (±1 sigma) of 670 ± 40 and 759 ± 40 years old; the less dense Shorea johorensis and Shorea superba trees at Danum yielded ages of 240 ± 40 and 330 ± 40 years, respectively. All trees studied exhibit an increase in the IWUE since AD 1960. This reflects, in part, a response of the forest to increasing atmospheric carbon dioxide concentration. Unlike studies of some northern European trees, no clear plateau in this response was observed. A change in the IWUE implies an associated modification of the local carbon and/or hydrological cycles. To resolve these uncertainties, a shift in emphasis away from high-resolution studies towards long, well-replicated time series is proposed to develop the environmental data essential for model evaluation. Identification of old (greater than 700 years) ringless trees demonstrates their potential in assessing the impacts of climatic and atmospheric change. It also shows the scientific and applied value of a conservation policy that ensures the survival of primary forest containing particularly old trees (as in Imbak Canyon and Danum).

Matched MeSH terms: Carbon Isotopes/chemistry
Fulltext Long-term succession in a coal seam microbiome during in situ biostimulation of coalbed-methane generation

Beckmann S, Luk AWS, Gutierrez-Zamora ML, Chong NHH, Thomas T, Lee M, et al.

ISME J, 2019 03;13(3):632-650.
PMID: 30323265 DOI: 10.1038/s41396-018-0296-5

Despite the significance of biogenic methane generation in coal beds, there has never been a systematic long-term evaluation of the ecological response to biostimulation for enhanced methanogenesis in situ. Biostimulation tests in a gas-free coal seam were analysed over 1.5 years encompassing methane production, cell abundance, planktonic and surface associated community composition and chemical parameters of the coal formation water. Evidence is presented that sulfate reducing bacteria are energy limited whilst methanogenic archaea are nutrient limited. Methane production was highest in a nutrient amended well after an oxic preincubation phase to enhance coal biofragmentation (calcium peroxide amendment). Compound-specific isotope analyses indicated the predominance of acetoclastic methanogenesis. Acetoclastic methanogenic archaea of the Methanosaeta and Methanosarcina genera increased with methane concentration. Acetate was the main precursor for methanogenesis, however more acetate was consumed than methane produced in an acetate amended well. DNA stable isotope probing showed incorporation of 13C-labelled acetate into methanogenic archaea, Geobacter species and sulfate reducing bacteria. Community characterisation of coal surfaces confirmed that methanogenic archaea make up a substantial proportion of coal associated biofilm communities. Ultimately, methane production from a gas-free subbituminous coal seam was stimulated despite high concentrations of sulfate and sulfate-reducing bacteria in the coal formation water. These findings provide a new conceptual framework for understanding the coal reservoir biosphere.

Matched MeSH terms: Carbon Isotopes/analysis
Synthesis of new indazole based dual inhibitors of α-glucosidase and α-amylase enzymes, their in vitro, in silico and kinetics studies

Rafique R, Khan KM, Arshia, Kanwal, Chigurupati S, Wadood A, et al.

Bioorg Chem, 2020 01;94:103195.
PMID: 31451297 DOI: 10.1016/j.bioorg.2019.103195

The current study describes the discovery of novel inhibitors of α-glucosidase and α-amylase enzymes. For that purpose, new hybrid analogs of N-hydrazinecarbothioamide substituted indazoles 4-18 were synthesized and fully characterized by EI-MS, FAB-MS, HRFAB-MS, 1H-, and 13C NMR spectroscopic techniques. Stereochemistry of the imine double bond was established by NOESY measurements. All derivatives 4-18 with their intermediates 1-3, were evaluated for in vitro α-glucosidase and α-amylase enzyme inhibition. It is worth mentioning that all synthetic compounds showed good inhibition potential in the range of 1.54 ± 0.02-4.89 ± 0.02 µM for α-glucosidase and for α-amylase 1.42 ± 0.04-4.5 ± 0.18 µM in comparison with the standard acarbose (IC50 value of 1.36 ± 0.01 µM). In silico studies were carried out to rationalize the mode of binding interaction of ligands with the active site of enzymes. Moreover, enzyme inhibitory kinetic characterization was also performed to understand the mechanism of enzyme inhibition.

Matched MeSH terms: Carbon Isotopes
Fulltext Olecranon Osteotomy Approach for Complex AO-13C Fractures of Distal Humerus: A Prospective Analysis of 24 Cases

Singh R, Singh H, Kanodia N

Malays Orthop J, 2019 Mar;13(1):30-35.
PMID: 31001381 DOI: 10.5704/MOJ.1903.005

Introduction: Olecranon osteotomy is well described approach for complex intra-articular distal humeral fractures. In this study, we investigated the usefulness and complications of olecranon osteotomy approach for such fractures. We hypothesise that outcome is comparable in young adults and middle age group and also functional outcome is independent of fracture subtype following surgical fixation. Materials and Methods: Between December 2012 and September 2015, twenty-four adult patients (male: 15, female: 9) having mean age of 41.4 years with closed intra-articular fracture (AO-13C) were surgically managed using olecranon osteotomy approach and were followed-up for a mean of 28.5 months (range: 22-35 months). Functional outcome was measured using Mayo Elbow Performance Score (MEPS) and complications were observed. Statistical analysis was done using Student t-test and Kruskal Wallis test. Results: All fractures united by the end of three months. Mean elbow flexion achieved was 123°, mean extension lag was 9° and mean active arc of motion was 114°. Mean MEPS was 87 (excellent: 8, good: 14, fair: 1 and poor: 1). Post-operative transient ulnar nerve palsy was noted in two cases, heterotopic ossification (HO) was in one case, infection in two cases, implant prominence in five and elbow stiffness in three cases. Motion arc was higher in young adults and MEPS was comparable in both age group. Functional outcome was also dependent on fracture subtype. Conclusion: The olecranon osteotomy approach for distal humerus fractures had good functional outcome with fewer complications. Joint congruity and fixation could easily be assessed intraoperatively.

Matched MeSH terms: Carbon Isotopes
Acetate and glucose utilisation and lipid synthesis by cold-acclimated and hypothermic rat-brain homogenates

Perumal R, Bhattathiry EP

Med J Malaya, 1970 Mar;24(3):208-11.
PMID: 4246803
Matched MeSH terms: Carbon Isotopes
Green synthesis of selenium-N-heterocyclic carbene compounds: Evaluation of antimicrobial and anticancer potential

Kamal A, Nazari V M, Yaseen M, Iqbal MA, Ahamed MBK, Majid ASA, et al.

Bioorg Chem, 2019 09;90:103042.
PMID: 31226469 DOI: 10.1016/j.bioorg.2019.103042

Three benzimidazolium salts (III-V) and respective selenium adducts (VI-VIII) were designed, synthesized and characterized by various analytical techniques (FT-IR and NMR 1H, 13C). Selected salts and respective selenium N-Heterocyclic carbenes (selenium-NHC) adducts were tested in vitro against Cervical Cancer Cell line (Hela), Breast Adenocarcinoma cell line (MCF-7), Retinal Ganglion Cell line (RGC-5) and Mouse Melanoma Cell line (B16F10) using MTT assay and the results were compared with standard drug 5-Fluorouracil. Se-NHC compounds and azolium salts showed significant anticancer potential. Molecular docking studies of compounds (VI, VII and VIII) showed strong binding energies and ligand affinity toward following angiogenic factors: VEGF-A (vascular endothelial growth factor A), EGF (human epidermal growth factor), HIF (Hypoxia-inducible factor) and COX-1 (Cyclooxygenase-1) suggesting that the anticancer activity of adducts (VI, VII and VIII) may be due to their strong anti-angiogenic effect. In addition, compounds III-VIII were screened for their antibacterial and antifungal potential. Adduct VI was found to be potent anti-fungal agent against A. Niger with zone of inhibition (ZI) value 27.01 ± 0.251 mm which is better than standard drug Clotrimazole tested in parallel.

Matched MeSH terms: Carbon Isotopes