Displaying publications 381 - 389 of 389 in total

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  1. Tan SH, Normi YM, Leow AT, Salleh AB, Karjiban RA, Murad AM, et al.
    BMC Struct Biol, 2014 Mar 19;14:11.
    PMID: 24641837 DOI: 10.1186/1472-6807-14-11
    BACKGROUND: At least a quarter of any complete genome encodes for hypothetical proteins (HPs) which are largely non-similar to other known, well-characterized proteins. Predicting and solving their structures and functions is imperative to aid understanding of any given organism as a complete biological system. The present study highlights the primary effort to classify and cluster 1202 HPs of Bacillus lehensis G1 alkaliphile to serve as a platform to mine and select specific HP(s) to be studied further in greater detail.

    RESULTS: All HPs of B. lehensis G1 were grouped according to their predicted functions based on the presence of functional domains in their sequences. From the metal-binding group of HPs of the cluster, an HP termed Bleg1_2507 was discovered to contain a thioredoxin (Trx) domain and highly-conserved metal-binding ligands represented by Cys69, Cys73 and His159, similar to all prokaryotic and eukaryotic Sco proteins. The built 3D structure of Bleg1_2507 showed that it shared the βαβαββ core structure of Trx-like proteins as well as three flanking β-sheets, a 310 -helix at the N-terminus and a hairpin structure unique to Sco proteins. Docking simulations provided an interesting view of Bleg1_2507 in association with its putative cytochrome c oxidase subunit II (COXII) redox partner, Bleg1_2337, where the latter can be seen to hold its partner in an embrace, facilitated by hydrophobic and ionic interactions between the proteins. Although Bleg1_2507 shares relatively low sequence identity (47%) to BsSco, interestingly, the predicted metal-binding residues of Bleg1_2507 i.e. Cys-69, Cys-73 and His-159 were located at flexible active loops similar to other Sco proteins across biological taxa. This highlights structural conservation of Sco despite their various functions in prokaryotes and eukaryotes.

    CONCLUSIONS: We propose that HP Bleg1_2507 is a Sco protein which is able to interact with COXII, its redox partner and therefore, may possess metallochaperone and redox functions similar to other documented bacterial Sco proteins. It is hoped that this scientific effort will help to spur the search for other physiologically relevant proteins among the so-called "orphan" proteins of any given organism.

    Matched MeSH terms: Protein Structure, Secondary
  2. Abdul Hafid SR, Chakravarthi S, Nesaretnam K, Radhakrishnan AK
    PLoS One, 2013;8(9):e74753.
    PMID: 24069344 DOI: 10.1371/journal.pone.0074753
    Tocotrienol-rich fraction (TRF) from palm oil is reported to possess anti-cancer and immune-enhancing effects. In this study, TRF supplementation was used as an adjuvant to enhance the anti-cancer effects of dendritic cells (DC)-based cancer vaccine in a syngeneic mouse model of breast cancer. Female BALB/c mice were inoculated with 4T1 cells in mammary pad to induce tumor. When the tumor was palpable, the mice in the experimental groups were injected subcutaneously with DC-pulsed with tumor lysate (TL) from 4T1 cells (DC+TL) once a week for three weeks and fed daily with 1 mg TRF or vehicle. Control mice received unpulsed DC and were fed with vehicle. The combined therapy of using DC+TL injections and TRF supplementation (DC+TL+TRF) inhibited (p<0.05) tumor growth and metastasis. Splenocytes from the DC+TL+TRF group cultured with mitomycin-C (MMC)-treated 4T1 cells produced higher (p<0.05) levels of IFN-γ and IL-12. The cytotoxic T-lymphocyte (CTL) assay also showed enhanced tumor-specific killing (p<0.05) by CD8(+) T-lymphocytes isolated from mice in the DC+TL+TRF group. This study shows that TRF has the potential to be used as an adjuvant to enhance effectiveness of DC-based vaccines.
    Matched MeSH terms: Lung Neoplasms/secondary
  3. Hassan BA, Yusoff ZB, Hassali MA, Othman SB, Weiderpass E
    Asian Pac J Cancer Prev, 2012;13(9):4373-8.
    PMID: 23167346
    INTRODUCTION: Hypercalcemia is mainly caused by bone resorption due to either secretion of cytokines including parathyroid hormone-related protein (PTHrP) or bone metastases. However, hypercalcemia may occur in patients with or without bone metastases. The present study aimed to describe the effect of chemotherapy treatment, regimens and doses on calcium levels among breast and lung cancer patients with hypercalcemia.

    METHODS: We carried a review of medical records of breast and lung cancer patients hospitalized in years 2003 and 2009 at Penang General Hospital, a public tertiary care center in Penang Island, north of Malaysia. Patients with hypercalcemia (defined as a calcium level above 10.5 mg/dl) at the time of cancer diagnosis or during cancer treatment had their medical history abstracted, including presence of metastasis, chemotherapy types and doses, calcium levels throughout cancer treatment, and other co-morbidity. The mean calcium levels at first hospitalization before chemotherapy were compared with calcium levels at the end of or at the latest chemotherapy treatment. Statistical analysis was conducted using the Chi-square test for categorical data, logistic regression test for categorical variables, and Spearman correlation test, linear regression and the paired sample t tests for continuous data.

    RESULTS: Of a total 1,023 of breast cancer and 814 lung cancer patients identified, 292 had hypercalcemia at first hospitalization or during cancer treatment (174 breast and 118 lung cancer patients). About a quarter of these patients had advanced stage cancers: 26.4% had mild hypercalcemia (10.5-11.9 mg/dl), 55.5% had moderate (12-12.9 mg/dl), and 18.2% severe hypercalcemia (13-13.9; 14-16 mg/dl). Chemotherapy lowered calcium levels significantly both in breast and lung cancer patients with hypercalcemia; in particular with chemotherapy type 5-flurouracil+epirubicin+cyclophosphamide (FEC) for breast cancer, and gemcitabine+cisplatin in lung cancer.

    CONCLUSION: Chemotherapy decreases calcium levels in breast and lung cancer cases with hypercalcemia at cancer diagnosis, probably by reducing PTHrP levels.

    Matched MeSH terms: Bone Neoplasms/secondary
  4. Tan CW, Chan YF, Sim KM, Tan EL, Poh CL
    PLoS One, 2012;7(5):e34589.
    PMID: 22563456 DOI: 10.1371/journal.pone.0034589
    Enterovirus 71 (EV-71) is the main causative agent of hand, foot and mouth disease (HFMD). In recent years, EV-71 infections were reported to cause high fatalities and severe neurological complications in Asia. Currently, no effective antiviral or vaccine is available to treat or prevent EV-71 infection. In this study, we have discovered a synthetic peptide which could be developed as a potential antiviral for inhibition of EV-71. Ninety five synthetic peptides (15-mers) overlapping the entire EV-71 capsid protein, VP1, were chemically synthesized and tested for antiviral properties against EV-71 in human Rhabdomyosarcoma (RD) cells. One peptide, SP40, was found to significantly reduce cytopathic effects of all representative EV-71 strains from genotypes A, B and C tested, with IC(50) values ranging from 6-9.3 µM in RD cells. The in vitro inhibitory effect of SP40 exhibited a dose dependent concentration corresponding to a decrease in infectious viral particles, total viral RNA and the levels of VP1 protein. The antiviral activity of SP40 peptide was not restricted to a specific cell line as inhibition of EV-71 was observed in RD, HeLa, HT-29 and Vero cells. Besides inhibition of EV-71, it also had antiviral activities against CV-A16 and poliovirus type 1 in cell culture. Mechanism of action studies suggested that the SP40 peptide was not virucidal but was able to block viral attachment to the RD cells. Substitutions of arginine and lysine residues with alanine in the SP40 peptide at positions R3A, R4A, K5A and R13A were found to significantly decrease antiviral activities, implying the importance of positively charged amino acids for the antiviral activities. The data demonstrated the potential and feasibility of SP40 as a broad spectrum antiviral agent against EV-71.
    Matched MeSH terms: Protein Structure, Secondary
  5. Masello JF, Martínez J, Calderón L, Wink M, Quillfeldt P, Sanz V, et al.
    Parasit Vectors, 2018 Jun 19;11(1):357.
    PMID: 29921331 DOI: 10.1186/s13071-018-2940-3
    BACKGROUND: Parasites can exert selection pressure on their hosts through effects on survival, on reproductive success, on sexually selected ornament, with important ecological and evolutionary consequences, such as changes in population viability. Consequently, hemoparasites have become the focus of recent avian studies. Infection varies significantly among taxa. Various factors might explain the differences in infection among taxa, including habitat, climate, host density, the presence of vectors, life history and immune defence. Feeding behaviour can also be relevant both through increased exposure to vectors and consumption of secondary metabolites with preventative or therapeutic effects that can reduce parasite load. However, the latter has been little investigated. Psittaciformes (parrots and cockatoos) are a good model to investigate these topics, as they are known to use biological control against ectoparasites and to feed on toxic food. We investigated the presence of avian malaria parasites (Plasmodium), intracellular haemosporidians (Haemoproteus, Leucocytozoon), unicellular flagellate protozoans (Trypanosoma) and microfilariae in 19 Psittaciformes species from a range of habitats in the Indo-Malayan, Australasian and Neotropical regions. We gathered additional data on hemoparasites in wild Psittaciformes from the literature. We considered factors that may control the presence of hemoparasites in the Psittaciformes, compiling information on diet, habitat, and climate. Furthermore, we investigated the role of diet in providing antiparasitic secondary metabolites that could be used as self-medication to reduce parasite load.

    RESULTS: We found hemoparasites in only two of 19 species sampled. Among them, all species that consume at least one food item known for its secondary metabolites with antimalarial, trypanocidal or general antiparasitic properties, were free from hemoparasites. In contrast, the infected parrots do not consume food items with antimalarial or even general antiparasitic properties. We found that the two infected species in this study consumed omnivorous diets. When we combined our data with data from studies previously investigating blood parasites in wild parrots, the positive relationship between omnivorous diets and hemoparasite infestation was confirmed. Individuals from open habitats were less infected than those from forests.

    CONCLUSIONS: The consumption of food items known for their secondary metabolites with antimalarial, trypanocidal or general antiparasitic properties, as well as the higher proportion of infected species among omnivorous parrots, could explain the low prevalence of hemoparasites reported in many vertebrates.

    Matched MeSH terms: Secondary Metabolism
  6. Teh AH, Sim PF, Hisano T
    Biochem Biophys Res Commun, 2020 12 10;533(3):257-261.
    PMID: 33010888 DOI: 10.1016/j.bbrc.2020.09.064
    The alginate lyase AlyQ from Persicobacter sp. CCB-QB2 is a three-domained enzyme with a carbohydrate-binding module (CBM) from family 32. The CBM32 domain, AlyQB, binds enzymatically cleaved but not intact alginate. Co-crystallisation of AlyQB with the cleaved alginate reveals that it binds to the 4,5-unsaturated mannuronic acid of the non-reducing end. The binding pocket contains a conserved R248 that interacts with the sugar's carboxyl group, as well as an invariant W303 that stacks against the unsaturated pyranose ring. Targeting specifically the non-reducing end is more efficient than the reducing end since the latter consists of a mixture of mannuronic acid and guluronic acid. AlyQB also seems unable to bind these two saturated sugars as they contain OH groups that will clash with the pocket. Docking analysis of YeCBM32, which binds oligogalacturonic acid, shows that the stacking of the pyranose ring is shifted in order to accommodate the sugar's axial C1-OH, and its R69 is accordingly elevated to bind the sugar's carboxyl group. Unlike AlyQB, YeCBM32's binding pocket is able to accommodate both saturated and unsaturated galacturonic acid.
    Matched MeSH terms: Protein Structure, Secondary
  7. Pittock SJ, Berthele A, Fujihara K, Kim HJ, Levy M, Palace J, et al.
    N Engl J Med, 2019 08 15;381(7):614-625.
    PMID: 31050279 DOI: 10.1056/NEJMoa1900866
    BACKGROUND: Neuromyelitis optica spectrum disorder (NMOSD) is a relapsing, autoimmune, inflammatory disorder that typically affects the optic nerves and spinal cord. At least two thirds of cases are associated with aquaporin-4 antibodies (AQP4-IgG) and complement-mediated damage to the central nervous system. In a previous small, open-label study involving patients with AQP4-IgG-positive disease, eculizumab, a terminal complement inhibitor, was shown to reduce the frequency of relapse.

    METHODS: In this randomized, double-blind, time-to-event trial, 143 adults were randomly assigned in a 2:1 ratio to receive either intravenous eculizumab (at a dose of 900 mg weekly for the first four doses starting on day 1, followed by 1200 mg every 2 weeks starting at week 4) or matched placebo. The continued use of stable-dose immunosuppressive therapy was permitted. The primary end point was the first adjudicated relapse. Secondary outcomes included the adjudicated annualized relapse rate, quality-of-life measures, and the score on the Expanded Disability Status Scale (EDSS), which ranges from 0 (no disability) to 10 (death).

    RESULTS: The trial was stopped after 23 of the 24 prespecified adjudicated relapses, given the uncertainty in estimating when the final event would occur. The mean (±SD) annualized relapse rate in the 24 months before enrollment was 1.99±0.94; 76% of the patients continued to receive their previous immunosuppressive therapy during the trial. Adjudicated relapses occurred in 3 of 96 patients (3%) in the eculizumab group and 20 of 47 (43%) in the placebo group (hazard ratio, 0.06; 95% confidence interval [CI], 0.02 to 0.20; P<0.001). The adjudicated annualized relapse rate was 0.02 in the eculizumab group and 0.35 in the placebo group (rate ratio, 0.04; 95% CI, 0.01 to 0.15; P<0.001). The mean change in the EDSS score was -0.18 in the eculizumab group and 0.12 in the placebo group (least-squares mean difference, -0.29; 95% CI, -0.59 to 0.01). Upper respiratory tract infections and headaches were more common in the eculizumab group. There was one death from pulmonary empyema in the eculizumab group.

    CONCLUSIONS: Among patients with AQP4-IgG-positive NMOSD, those who received eculizumab had a significantly lower risk of relapse than those who received placebo. There was no significant between-group difference in measures of disability progression. (Funded by Alexion Pharmaceuticals; PREVENT ClinicalTrials.gov number, NCT01892345; EudraCT number, 2013-001150-10.).

    Matched MeSH terms: Secondary Prevention
  8. Chan SL, Ong TC, Gao YF, Tiong YS, Wang de Y, Chew FT, et al.
    J Immunol, 2008 Aug 15;181(4):2586-96.
    PMID: 18684949
    A high incidence of sensitization to Blomia tropicalis, the predominant house dust mite species in tropical regions, is strongly associated with allergic diseases in Singapore, Malaysia, and Brazil. IgE binding to the group 5 allergen, Blo t 5, is found to be the most prevalent among all B. tropicalis allergens. The NMR structure of Blo t 5 determined represents a novel helical bundle structure consisting of three antiparallel alpha-helices. Based on the structure and sequence alignment with other known group 5 dust mite allergens, surface-exposed charged residues have been identified for site-directed mutagenesis and IgE binding assays. Four charged residues, Glu76, Asp81, Glu86, and Glu91 at around the turn region connecting helices alpha2 and alpha3 have been identified to be involved in the IgE binding. Using overlapping peptides, we have confirmed that these charged residues are located on a major putative linear IgE epitope of Blo t 5 from residues 76-91 comprising the sequence ELKRTDLNILERFNYE. Triple and quadruple mutants have been generated and found to exhibit significantly lower IgE binding and reduced responses in skin prick tests. The mutants induced similar PBMC proliferation as the wild-type protein but with reduced Th2:Th1 cytokines ratio. Mass screening on a quadruple mutant showed a 40% reduction in IgE binding in 35 of 42 sera of atopic individuals. Findings in this study further stressed the importance of surface-charged residues on IgE binding and have implications in the cross-reactivity and use of Blo t 5 mutants as a hypoallergen for immunotherapy.
    Matched MeSH terms: Protein Structure, Secondary
  9. Khatib R, McKee M, Shannon H, Chow C, Rangarajan S, Teo K, et al.
    Lancet, 2016 Jan 2;387(10013):61-9.
    PMID: 26498706 DOI: 10.1016/S0140-6736(15)00469-9
    BACKGROUND: WHO has targeted that medicines to prevent recurrent cardiovascular disease be available in 80% of communities and used by 50% of eligible individuals by 2025. We have previously reported that use of these medicines is very low, but now aim to assess how such low use relates to their lack of availability or poor affordability.
    METHODS: We analysed information about availability and costs of cardiovascular disease medicines (aspirin, β blockers, angiotensin-converting enzyme inhibitors, and statins) in pharmacies gathered from 596 communities in 18 countries participating in the Prospective Urban Rural Epidemiology (PURE) study. Medicines were considered available if present at the pharmacy when surveyed, and affordable if their combined cost was less than 20% of household capacity-to-pay. We compared results from high-income, upper middle-income, lower middle-income, and low-income countries. Data from India were presented separately given its large, generic pharmaceutical industry.
    FINDINGS: Communities were recruited between Jan 1, 2003, and Dec 31, 2013. All four cardiovascular disease medicines were available in 61 (95%) of 64 urban and 27 (90%) of 30 rural communities in high-income countries, 53 (80%) of 66 urban and 43 (73%) of 59 rural communities in upper middle-income countries, 69 (62%) of 111 urban and 42 (37%) of 114 rural communities in lower middle-income countries, eight (25%) of 32 urban and one (3%) of 30 rural communities in low-income countries (excluding India), and 34 (89%) of 38 urban and 42 (81%) of 52 rural communities in India. The four cardiovascular disease medicines were potentially unaffordable for 0·14% of households in high-income countries (14 of 9934 households), 25% of upper middle-income countries (6299 of 24,776), 33% of lower middle-income countries (13,253 of 40,023), 60% of low-income countries (excluding India; 1976 of 3312), and 59% households in India (9939 of 16,874). In low-income and middle-income countries, patients with previous cardiovascular disease were less likely to use all four medicines if fewer than four were available (odds ratio [OR] 0·16, 95% CI 0·04-0·57). In communities in which all four medicines were available, patients were less likely to use medicines if the household potentially could not afford them (0·16, 0·04-0·55).
    INTERPRETATION: Secondary prevention medicines are unavailable and unaffordable for a large proportion of communities and households in upper middle-income, lower middle-income, and low-income countries, which have very low use of these medicines. Improvements to the availability and affordability of key medicines is likely to enhance their use and help towards achieving WHO's targets of 50% use of key medicines by 2025.
    FUNDING: Population Health Research Institute, the Canadian Institutes of Health Research, Heart and Stroke Foundation of Ontario, AstraZeneca (Canada), Sanofi-Aventis (France and Canada), Boehringer Ingelheim (Germany and Canada), Servier, GlaxoSmithKline, Novartis, King Pharma, and national or local organisations in participating countries.
    Matched MeSH terms: Secondary Prevention
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