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Gopal P, Abazeed M. High-Throughput Phenotyping of BRAF Mutations Reveals Categories of Mutations That Confer Resistance to Radiation. Int J Radiat Oncol Biol Phys 2017. [DOI: 10.1016/j.ijrobp.2017.06.2023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Gopal P, Tasneen R, Yee M, Lanoix JP, Sarathy J, Rasic G, Li L, Dartois V, Nuermberger E, Dick T. In Vivo-Selected Pyrazinoic Acid-Resistant Mycobacterium tuberculosis Strains Harbor Missense Mutations in the Aspartate Decarboxylase PanD and the Unfoldase ClpC1. ACS Infect Dis 2017; 3:492-501. [PMID: 28271875 PMCID: PMC5514395 DOI: 10.1021/acsinfecdis.7b00017] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Through mutant selection on agar containing pyrazinoic acid (POA), the bioactive form of the prodrug pyrazinamide (PZA), we recently showed that missense mutations in the aspartate decarboxylase PanD and the unfoldase ClpC1, and loss-of-function mutation of polyketide synthases Mas and PpsA-E involved in phthiocerol dimycocerosate synthesis, cause resistance to POA and PZA in Mycobacterium tuberculosis. Here we first asked whether these in vitro-selected POA/PZA-resistant mutants are attenuated in vivo, to potentially explain the lack of evidence of these mutations among PZA-resistant clinical isolates. Infection of mice with panD, clpC1, and mas/ppsA-E mutants showed that whereas growth of clpC1 and mas/ppsA-E mutants was attenuated, the panD mutant grew as well as the wild-type. To determine whether these resistance mechanisms can emerge within the host, mice infected with wild-type M. tuberculosis were treated with POA, and POA-resistant colonies were confirmed for PZA and POA resistance. Genome sequencing revealed that 82 and 18% of the strains contained missense mutations in panD and clpC1, respectively. Consistent with their lower fitness and POA resistance level, independent mas/ppsA-E mutants were not found. In conclusion, we show that the POA/PZA resistance mechanisms due to panD and clpC1 missense mutations are recapitulated in vivo. Whereas the representative clpC1 mutant was attenuated for growth in the mouse infection model, providing a possible explanation for their absence among clinical isolates, the growth kinetics of the representative panD mutant was unaffected. Why POA/PZA resistance-conferring panD mutations are observed in POA-treated mice but not yet among clinical strains isolated from PZA-treated patients remains to be determined.
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Parthiban C, Varudharasu D, Shanmugam M, Gopal P, Ragunath C, Thomas L, Nitz M, Ramasubbu N. Structural and functional analysis of de-N-acetylase PgaB from periodontopathogenAggregatibacter actinomycetemcomitans. Mol Oral Microbiol 2016; 32:324-340. [DOI: 10.1111/omi.12175] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/29/2016] [Indexed: 01/09/2023]
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Priyavathi P, Kavitha V, Gopal P. Complex Nature of Infection Associated with Yellow Vein Mosaic Disease in Bhendi ( Abelmoschus esculentus). CURR SCI INDIA 2016. [DOI: 10.18520/cs/v111/i9/1511-1515] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Gopal P, Yee M, Sarathy J, Low JL, Sarathy JP, Kaya F, Dartois V, Gengenbacher M, Dick T. Pyrazinamide Resistance Is Caused by Two Distinct Mechanisms: Prevention of Coenzyme A Depletion and Loss of Virulence Factor Synthesis. ACS Infect Dis 2016; 2:616-626. [PMID: 27759369 DOI: 10.1021/acsinfecdis.6b00070] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Pyrazinamide (PZA) is a critical component of first- and second-line treatments of tuberculosis (TB), yet its mechanism of action largely remains an enigma. We carried out a genetic screen to isolate Mycobacterium bovis BCG mutants resistant to pyrazinoic acid (POA), the bioactive derivative of PZA, followed by whole genome sequencing of 26 POA resistant strains. Rather than finding mutations in the proposed candidate targets fatty acid synthase I and ribosomal protein S1, we found resistance conferring mutations in two pathways: missense mutations in aspartate decarboxylase panD, involved in the synthesis of the essential acyl carrier coenzyme A (CoA), and frameshift mutations in the vitro nonessential polyketide synthase genes mas and ppsA-E, involved in the synthesis of the virulence factor phthiocerol dimycocerosate (PDIM). Probing for cross resistance to two structural analogs of POA, nicotinic acid and benzoic acid, showed that the analogs share the PDIM- but not the CoA-related mechanism of action with POA. We demonstrated that POA depletes CoA in wild-type bacteria, which is prevented by mutations in panD. Sequencing 10 POA-resistant Mycobacterium tuberculosis H37Rv isolates confirmed the presence of at least 2 distinct mechanisms of resistance to the drug. The emergence of resistance through the loss of a virulence factor in vitro may explain the lack of clear molecular patterns in PZA-resistant clinical isolates, other than mutations in the prodrug-converting enzyme. The apparent interference of POA with virulence pathways may contribute to the drug's excellent in vivo efficacy compared to its modest in vitro potency.
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Oshan V, Plant N, Gopal P, Rajai A, Roberts SA, Walker RWM. The effect of age and increasing head-up tilt on pre-oxygenation times in children: a randomised exploratory study. Anaesthesia 2016; 71:429-36. [DOI: 10.1111/anae.13379] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/07/2015] [Indexed: 11/29/2022]
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Via LE, Savic R, Weiner DM, Zimmerman MD, Prideaux B, Irwin SM, Lyon E, O’Brien P, Gopal P, Eum S, Lee M, Lanoix JP, Dutta NK, Shim T, Cho JS, Kim W, Karakousis PC, Lenaerts A, Nuermberger E, Barry CE, Dartois V. Host-Mediated Bioactivation of Pyrazinamide: Implications for Efficacy, Resistance, and Therapeutic Alternatives. ACS Infect Dis 2015; 1:203-214. [PMID: 26086040 DOI: 10.1021/id500028m] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Pyrazinamide has played a critical role in shortening therapy against drug-sensitive, drug-resistant, active, and latent tuberculosis (TB). Despite widespread recognition of its therapeutic importance, the sterilizing properties of this 60-year-old drug remain an enigma given its rather poor activity in vitro. Here we revisit longstanding paradigms and offer pharmacokinetic explanations for the apparent disconnect between in vitro activity and clinical impact. We show substantial host-mediated conversion of prodrug pyrazinamide (PZA) to the active form, pyrazinoic acid (POA), in TB patients and in animal models. We demonstrate favorable penetration of this pool of circulating POA from plasma into lung tissue and granulomas, where the pathogen resides. In standardized growth inhibition experiments, we show that POA exhibits superior in vitro potency compared to PZA, indicating that the vascular supply of host-derived POA may contribute to the in vivo efficacy of PZA, thereby reducing the apparent discrepancy between in vitro and in vivo activity. However, the results also raise the possibility that subinhibitory concentrations of POA generated by the host could fuel the emergence of resistance to both PZA and POA. In contrast to widespread expectations, we demonstrate good oral bioavailability and exposure in preclinical species in pharmacokinetic studies of oral POA. Baseline exposure of oral POA can be further increased by the xanthine oxidase inhibitor and approved gout drug allopurinol. These promising results pave the way for clinical investigations of oral POA as a therapeutic alternative or an add-on to overcome PZA resistance and salvage this essential TB drug.
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Gopal P, Dick T. The new tuberculosis drug Perchlozone® shows cross-resistance with thiacetazone. Int J Antimicrob Agents 2015; 45:430-3. [DOI: 10.1016/j.ijantimicag.2014.12.026] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Revised: 12/17/2014] [Accepted: 12/17/2014] [Indexed: 12/14/2022]
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Gopal P, Gosker HR, Theije CCD, Eurlings IM, Sell DR, Monnier VM, Reynaert NL. Effect of chronic hypoxia on RAGE and its soluble forms in lungs and plasma of mice. Biochim Biophys Acta Mol Basis Dis 2015; 1852:992-1000. [PMID: 25703138 DOI: 10.1016/j.bbadis.2015.02.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Revised: 01/30/2015] [Accepted: 02/12/2015] [Indexed: 12/24/2022]
Abstract
The receptor for advanced glycation end products (RAGE) is a multi-ligand receptor. Alternative splicing and enzymatic shedding produce soluble forms that protect against damage by ligands including Advanced Glycation End products (AGEs). A link between RAGE and oxygen levels is evident from studies showing RAGE-mediated injury following hyperoxia. The effect of hypoxia on pulmonary RAGE expression and circulating sRAGE levels is however unknown. Therefore mice were exposed to chronic hypoxia for 21 d and expression of RAGE, sheddases in lungs and circulating sRAGE were determined. In addition, accumulation of AGEs in lungs and expression of the AGE detoxifying enzyme GLO1 and receptors were evaluated. In lung tissue gene expression of total RAGE, variants 1 and 3 were elevated in mice exposed to hypoxia, whereas mRAGE and sRAGE protein levels were decreased. In the hypoxic group plasma sRAGE levels were enhanced. Although the levels of pro-ADAM10 were elevated in lungs of hypoxia exposed mice, the relative amount of the active form was decreased and gelatinase activity unaffected. In the lungs, the RAGE ligand HMGB1 was decreased and of the AGEs, only LW-1 was increased by chronic hypoxia. Gene expression of AGE receptors 2 and 3 was significantly upregulated. Chronic hypoxia is associated with downregulation of pulmonary RAGE protein levels, but a relative increase in sRAGE. These alterations might be part of the adaptive and protective response mechanism to chronic hypoxia and are not associated with AGE formation except for the fluorophore LW-1 which emerges as a novel marker of tissue hypoxia.
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Gopal P, Dick T. Reactive dirty fragments: implications for tuberculosis drug discovery. Curr Opin Microbiol 2014; 21:7-12. [DOI: 10.1016/j.mib.2014.06.015] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Revised: 06/19/2014] [Accepted: 06/29/2014] [Indexed: 01/01/2023]
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Raghu P, Reddy TM, Gopal P, Reddaiah K, Sreedhar N. A novel horseradish peroxidase biosensor towards the detection of dopamine: A voltammetric study. Enzyme Microb Technol 2014; 57:8-15. [DOI: 10.1016/j.enzmictec.2014.01.002] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2013] [Revised: 01/02/2014] [Accepted: 01/04/2014] [Indexed: 11/30/2022]
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Gopal P, Reddy TM, Nagaraju C, Narasimha G. Correction: Preparation, characterization and analytical application of an electrochemical laccase biosensor towards low level determination of isoprenaline in human serum samples. RSC Adv 2014. [DOI: 10.1039/c4ra90046d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Gopal P, Reddy TM, Nagaraju C, Narasimha G. Preparation, characterization and analytical application of an electrochemical laccase biosensor towards low level determination of isoprenaline in human serum samples. RSC Adv 2014. [DOI: 10.1039/c4ra09989c] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A novel electrochemical biosensor has been developed based on the immobilization of multiwalled carbon nanotubes (MWCNT) followed by sol–gel entrapment of laccase (Lac) enzyme on to the GCE.
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Prasad M, Gopal P, Mannam G. Continuous monitoring of blood glucose using a fiberoptic-based intravascular sensor during postoperative care in the ICU. Crit Care 2014. [PMCID: PMC4069445 DOI: 10.1186/cc13632] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
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Tan D, Yopp A, Beg MS, Gopal P, Singal AG. Meta-analysis: underutilisation and disparities of treatment among patients with hepatocellular carcinoma in the United States. Aliment Pharmacol Ther 2013; 38:703-12. [PMID: 23957569 PMCID: PMC3777750 DOI: 10.1111/apt.12450] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Revised: 06/18/2013] [Accepted: 07/21/2013] [Indexed: 12/23/2022]
Abstract
BACKGROUND Despite wide availability of treatment options for hepatocellular carcinoma (HCC), several studies have suggested underutilisation in clinical practice. AIMS To quantify utilisation rates for HCC treatment among patients with HCC in the United States, and to summarise patterns of association between utilisation rates and patient socio-demographic characteristics. METHODS We performed a systematic literature review using the Medline database from January 1989 to March 2013. Two investigators independently extracted data on patient populations, study methods and results using standardised forms. Pooled treatment rates for any treatment and curative treatment, with 95% confidence intervals, were calculated. Prespecified subgroup analysis was performed to identify patient-level correlates of treatment utilisation. RESULTS We identified 24 studies that met inclusion criteria. The pooled rates of any treatment and curative treatment were 52.8% (95% CI 52.2-53.4%) and 21.8% (95% CI 21.4-22.1%) respectively. Among patients diagnosed at an early stage, the pooled curative treatment rate was 59.0% (95% CI 58.1-59.9%). Elderly, non-Caucasians and patients of low socioeconomic status had lower treatment rates than their counterparts. CONCLUSIONS Rates of HCC treatment in the United States, including curative treatment rates among patients detected at an early stage, are disappointingly low. Future efforts should focus on identifying appropriate intervention targets to increase treatment rates and reduce socio-demographic disparities.
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Ling BMT, Gopinadhan S, Kok WK, Shankar SR, Gopal P, Bharathy N, Wang Y, Taneja R. G9a mediates Sharp-1-dependent inhibition of skeletal muscle differentiation. Mol Biol Cell 2012; 23:4778-85. [PMID: 23087213 PMCID: PMC3521685 DOI: 10.1091/mbc.e12-04-0311] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Sharp-1, a basic helix-loop-helix transcription factor, is a potent repressor of skeletal muscle differentiation and is dysregulated in muscle pathologies. However, the mechanisms by which it inhibits myogenesis are not fully understood. Here we show that G9a, a lysine methyltransferase, is involved in Sharp-1-mediated inhibition of muscle differentiation. We demonstrate that G9a directly interacts with Sharp-1 and enhances its ability to transcriptionally repress the myogenin promoter. Concomitant with a differentiation block, G9a-dependent histone H3 lysine 9 dimethylation (H3K9me2) and MyoD methylation are apparent upon Sharp-1 overexpression in muscle cells. RNA interference-mediated reduction of G9a or pharmacological inhibition of its activity erases these repressive marks and rescues the differentiation defect imposed by Sharp-1. Our findings provide new insights into Sharp-1-dependent regulation of myogenesis and identify epigenetic mechanisms that could be targeted in myopathies characterized by elevated Sharp-1 levels.
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Jaglal MV, Desai P, Schaefer G, Miller DM, Ghim S, Gopal P, Hanan F, Jenson AB. Incidence of human papillomavirus in head and neck squamous cell carcinomas. J Clin Oncol 2008. [DOI: 10.1200/jco.2008.26.15_suppl.17020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Sabitha G, Gopal P, Yadav JS. Versatile Approach for the Asymmetric Synthesis of (R)‐ and (S)‐Massoialactones. SYNTHETIC COMMUN 2007. [DOI: 10.1080/00397910701229107] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Gopal P, Pravin Kumar P, Sinilal B, Jose J, Kasin Yadunandam A, Usha R. Differential roles of C4 and betaC1 in mediating suppression of post-transcriptional gene silencing: evidence for transactivation by the C2 of Bhendi yellow vein mosaic virus, a monopartite begomovirus. Virus Res 2007; 123:9-18. [PMID: 16949698 DOI: 10.1016/j.virusres.2006.07.014] [Citation(s) in RCA: 114] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2006] [Revised: 07/21/2006] [Accepted: 07/21/2006] [Indexed: 11/28/2022]
Abstract
Bhendi yellow vein mosaic disease (BYVMD) is caused by the association of a DNA beta satellite with a begomovirus component. The begomovirus component has two promoters, one in the virion sense (V-sense) and the other in the complementary sense (C-sense) in the intergenic region (IR). To study the promoter activities of V-sense and C-sense promoters, mGFP gene fusion was made downstream to the promoters. Transient and stable expressions in N. benthamiana leaves showed significant GFP expression under C-sense promoter whereas the expression under the V-sense promoter was very weak in the absence of the transactivator C2. Untransformed N. benthamiana plants were agroinfiltrated with binary vector constructs containing V-sense-GFP alone or along with C1, C2, C4, V1, V2 or betaC1 (in both sense and antisense orientations) to understand the roles of these gene products in transactivation and/or suppression of post-transcriptional gene silencing (PTGS). The results showed strong suppression of gene silencing activities for C4 and betaC1 but a weak activity for C2. The suppression activities were also confirmed using gfp-silenced GFP16c/GFPi plants by agroinfiltration and agroinoculation. The expression of C4 and betaC1 as transgenes produced abnormal phenotypic growth compared to the other viral genes mentioned above, further supporting their suppressor function.
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Ahmed M, Prasad J, Gill H, Stevenson L, Gopal P. Impact of consumption of different levels of Bifidobacterium lactis HN019 on the intestinal microflora of elderly human subjects. J Nutr Health Aging 2007; 11:26-31. [PMID: 17315077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
BACKGROUND Age-related changes in the physiology and intestinal function of the elderly render them more susceptible to gut-related illnesses. Probiotic dietary supplementation has been shown to enhance the health indices in the elderly. OBJECTIVE To determine the effect of three different doses [5 x 109 CFU/day (high), 1.0 x 109 CFU/day (medium) and 6.5 x 107 CFU/day (low)] of Bifidobacterium lactis HN019 (DR10TM) on the intestinal flora of elderly human subjects and the dose response effect. DESIGN Randomised, double-blind and placebo-controlled human dietary intervention study consisting of four groups of 20 elderly (over 60 years old) volunteers. Each volunteer consumed 250 mL per day of reconstituted skim milk (RSM) which either did not contain any probiotic supplement (placebo group) or contained B. lactis HN019 at different levels (low, medium and high dose groups). The study comprised three stages: a 2-week pre-intervention (without any supplement), followed by 4 weeks of test feeding (dietary intervention) and then a 2-week washout period. RESULTS After dietary intervention, statistically significant increases in bifidobacteria, lactobacilli and enterococci were observed. At the end of the 4-week feeding period the mean number of bifidobacteria recorded in the placebo group were 9.31 +/- 0.01 log CFU/g of faeces. In the high, medium and low dose groups the bifidobacteria levels were significantly (p < 0.006) higher (9.88 +/- 0.1, 9.75 +/- 0.14 and 9.74 +/- 0.11 log CFU/g of faeces, respectively), when compared to the respective pre-intervention levels. There were no significant differences (p superior 0.05) between the responses of the different dose groups, indicating that even the lowest dose tested augmented the changes in bifidobacteria. Similar trends were observed for lactobacilli and enterococci. In contrast, the counts of enterobacteria were reduced in all the probiotic dose groups. CONCLUSION The present study showed that dietary supplementation with B. lactis HN019 significantly increased the number of resident bifidobacteria and reduced the enterobacteria counts. In addition, enterococci and lactobacilli were also increased. Based on this study and already published clinical evidence (4, 5, 8, 9) we conclude that, B. lactis HN019 is a suitable probiotic for elderly human subjects and even the lowest dose (6.5 x 107 CFU/day) tested is able to confer desired changes in the intestinal microflora.
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Crittenden R, Bird AR, Gopal P, Henriksson A, Lee YK, Playne MJ. Probiotic research in Australia, New Zealand and the Asia-Pacific region. Curr Pharm Des 2005; 11:37-53. [PMID: 15638751 DOI: 10.2174/1381612053382304] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Although the epicentres of probiotic research in the past decade have been Japan and Europe, researchers in the Asia-Pacific region have actively contributed to the growing understanding of the intestinal microbial ecosystem, and interactions between gut bacteria, diet and health of the human host. A number of new probiotic strains have been developed in the region that have been demonstrated to have beneficial impacts on health in animal and human trials, including improved protection against intestinal pathogens and modulation of the immune system. Probiotics targeted to animals, including aquaculture, feature heavily in many Asian countries. Developments in probiotic technologies have included microencapsulation techniques, antimicrobial production in fermented meats, and synbiotic combinations. In particular, the impact of resistant starch on the intestinal environment and fermentation by intestinal bacteria has been intensively studied and new probiotic strains selected specifically for synbiotic combinations with resistant starch. This paper provides an overview of probiotic research within Australia, New Zealand and a number of Asian countries, and lists scientists in the Asia-Pacific region involved in various aspects of probiotic research and development.
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Gopal P, Iyawoo K, Hooi Lai Ngoh, Parameswary V. Lung cancer: a review of 589 Malaysian patients. THE MEDICAL JOURNAL OF MALAYSIA 1988; 43:288-96. [PMID: 2853822] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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Ballou L, Gopal P, Krummel B, Tammi M, Ballou CE. A mutation that prevents glucosylation of the lipid-linked oligosaccharide precursor leads to underglycosylation of secreted yeast invertase. Proc Natl Acad Sci U S A 1986; 83:3081-5. [PMID: 3517849 PMCID: PMC323456 DOI: 10.1073/pnas.83.10.3081] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
A mutant of Saccharomyces cerevisiae with the genotype mnn1 mnn2 mnn9 gls1 synthesizes mannoproteins with oligosaccharides having the composition Glc3Man10Glc-NAc2- owing to the mnn9 defect, which prevents synthesis of the outer chain, the mnn1 defect, which prevents branching of the core, and the gls1 mutation, which prevents deglucosylation of the resultant glycoprotein as a consequence of a defective glucosidase-I [Tsai, P.-K., Ballou, L., Esmon, B., Schekman, R. & Ballou, C. E. (1984) Proc. Natl. Acad. Sci. USA 81, 6340-6343]. (The mnn2 defect is not expressed in presence of the mnn9 mutation.) This strain spontaneously forms new colonies in which gls1 is suppressed owing to a defect in synthesis of dolichol phosphoglucose, the glucosylation substrate. The new mutant, designated mnn1 mnn2 mnn9 gls1 dpg1, synthesizes and secretes invertase (EC 3.2.1.26) that has a higher mobility on native gel electrophoresis than that made by the parent strain, the consequence of a reduction in both the size and the number of carbohydrate chains. The mannoprotein chains have the mnn1 mnn9 structure (Man10Glc-NAc2-), and the invertase is resolved by gel electrophoresis in sodium dodecyl sulfate into two major and two minor bands that represent homologs with about 4-7 carbohydrate units, in contrast to about 8-11 chains in the parent strain. Thus, the inability to glucosylate the lipid-linked precursor reduces the efficiency of glycosylation of the protein chains. The genetic defect is in synthesis of the glucose donor dolichol phosphoglucose, but the mutation is nonallelic with the reported alg5-1 mutation, which has a similar phenotype [Runge, K. W., Huffaker, T. C. & Robbins, P. W. (1984) J. Biol. Chem. 259, 412-417].
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Gopal P, Sullivan PA, Shepherd MG. Isolation and structure of glucan from regenerating spheroplasts of Candida albicans. JOURNAL OF GENERAL MICROBIOLOGY 1984; 130:1217-25. [PMID: 6381644 DOI: 10.1099/00221287-130-5-1217] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Regenerating spheroplasts of Candida albicans formed organized glucan nets in liquid culture. The nets consisted of interwoven microfibrils about 50 nm wide, but of an undetermined length. Partial acid hydrolysis of the polysaccharide showed the presence of chains of beta(1----3)- and beta(1----6)-linked glucose residues, but no intrachain beta(1----3) and beta(1----6) linkages. Periodate oxidation and GLC of the methylated glucan indicated a highly branched polymer (9.5% branch points). Sequential enzymic degradation of the isolated nets confirmed the presence of chains of beta(1----3)- and beta(1----6)-linked glucose residues. Degradation by (1----3)-beta- and (1----6)-beta-glucanase released 23% (w/w) and 30% (w/w) respectively of the carbohydrate as glucose equivalents. The residual material was degraded by chitinase. Equal amounts of N-acetylglucosamine and glucose equivalents were detected in the chitinase hydrolysate, suggesting a possible linkage between glucan and chitin. Our data indicate that the cell wall of C. albicans contains at least two highly branched glucans with predominantly beta(1----3) or beta(1----6) linkages.
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Gopal P, Sullivan PA, Shepherd MG. Metabolism of [14C]glucose by regenerating spheroplasts of Candida albicans. JOURNAL OF GENERAL MICROBIOLOGY 1984; 130:325-35. [PMID: 6427397 DOI: 10.1099/00221287-130-2-325] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Spheroplasts of Candida albicans were regenerated in [14C]glucose and buffered magnesium sulphate (0.1 M-Tris/HCl; 0.5 M-MgSO4, pH 7.2) at 35 degrees C. Uptake of glucose by spheroplasts was faster than that by intact yeast cells. After 6 h, 65% of the glucose taken up by the yeast appeared as CO2 and 30% was incorporated into the cellular material. With spheroplasts, 55% of the glucose taken up was expired as CO2, 25% was excreted into the medium as other metabolites and 20% was incorporated into the cells. The regenerating spheroplasts excreted 14C-labelled carbohydrates into the medium which were fractionated on a Sephadex G-15 column. Acid hydrolysis of the low molecular-weight fraction yielded the following sugars: mannose (75.7%), fucose (3.8%), arabinose (3%), galactose (2.1%) and an unidentified monosaccharide (14%). Spheroplasts did not incorporate mannoprotein into the regenerated wall. The wall carbohydrate from regenerated spheroplasts was fractionated on the basis of solubility in sodium hydroxide. The alkali-insoluble fraction was analysed by sequential enzyme hydrolysis; 40% of the incorporated counts were associated with beta (1----3)-linked glucan and 50% with a mixed glucan comprising beta (1----3)- and beta (1----6)-linkages and chitin.
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