Displaying publications 1 - 20 of 40 in total

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  1. Makpol S, Yaacob N, Zainuddin A, Yusof YA, Ngah WZ
    Afr J Tradit Complement Altern Med, 2009 Jul 03;6(4):560-72.
    PMID: 20606778
    The objective of this study was to investigate the modulatory effect of Chlorella vulgaris on cultured fibroblast cells derived from young and old aged individuals focusing on DNA damage, telomere length and telomerase activity. Dose-response test of the algal extract on cells in both age groups revealed that optimum viability was observed at a concentration of 50 microg/ml. Results obtained showed that Chlorella vulgaris exhibited protective effects against H(2)O(2)-induced oxidative stress as shown by the reduction in damaged DNA caused by H(2)O(2) treatment (p<0.05) in Chlorella vulgaris pre- and post-treated groups (p<0.05). Pre-treatment of Chlorella vulgaris resulted in a significant decrease in DNA damage suggesting a bioprotective effect against free radical attacks. A decline in DNA damage was observed in post-treated cells which proves Chlorella vulgaris to present bioremediative properties. In cells induced with oxidative stress, telomere length decreased significantly coupled with a concomitant decline of telomerase activity (p<0.05). However, these reductions were prevented with prior and post treatment of Chlorella vulgaris. Therefore, we concluded that Chlorella vulgaris exhibited bioprotective effects especially in cells obtained from young donor but were more bioremediative for cells obtained from old donor as indicated by DNA damage, telomere shortening and reduction in telomerase activity.
    Matched MeSH terms: Telomere/drug effects*; Telomere/genetics
  2. Nasir NF, Kannan TP, Sulaiman SA, Shamsuddin S, Azlina A, Stangaciu S
    Age (Dordr), 2015 Jun;37(3):9797.
    PMID: 26028466 DOI: 10.1007/s11357-015-9797-6
    The belief that beekeepers live longer than anyone else is present since ages. However, no research has been done to explore the longevity of life in beekeepers. Here, we investigated the telomere length in 30 male beekeepers and 30 male non-beekeepers and associated them with the longevity of life using Southern analysis of terminal restriction fragments (TRFs) generated by Hinf I/Rsa I digestion of human genomic DNA using TeloTAGGG Telomere Length Assay. Interestingly, we found that the telomere length of male beekeepers was significantly longer than those of male non-beekeepers with a p value of less than 0.05, suggesting that beekeepers may have longer life compared to non-beekeepers. We further found that the consumption of bee products for a long period and frequent consumption of bee products per day are associated with telomere length. An increase of year in consuming bee products is associated with a mean increase in telomere length of 0.258 kbp. In addition, an increase in frequency of eating bee products per day was also associated with a mean increase of 2.66 kbp in telomere length. These results suggested that bee products might play some roles in telomere length maintenance.
    Matched MeSH terms: Telomere Homeostasis/physiology*
  3. Osahor AN, Tan CY, Sim EU, Lee CW, Narayanan K
    Anal Biochem, 2014 Oct 1;462:26-8.
    PMID: 24929088 DOI: 10.1016/j.ab.2014.05.030
    When recombineering bacterial artificial chromosomes (BACs), it is common practice to design the ends of the donor molecule with 50 bp of homology specifying its insertion site. We demonstrate that desired recombinants can be produced using intermolecular homologies as short as 15 bp. Although the use of shorter donor end regions decreases total recombinants by several fold, the frequency of recombinants with correctly inserted donor molecules was high enough for easy detection by simple polymerase chain reaction (PCR) screening. This observation may have important implications for the design of oligonucleotides for recombineering, including significant cost savings, especially for high-throughput projects that use large quantities of primers.
    Matched MeSH terms: Telomere/genetics
  4. Chen Q, Narayanan K
    Anal Biochem, 2011 Jul 1;414(1):169-71.
    PMID: 21396906 DOI: 10.1016/j.ab.2011.03.006
    The phage N15 protelomerase enzyme (TelN) is essential for the replication of its genome by resolution of its telRL domain, located within a telomerase occupancy site (tos), into hairpin telomeres. Isolation of TelN for in vitro processing of tos, however, is a highly complex process, requiring multiple purification steps. In this study a simplified protocol for crude total protein extraction is described that retains the tos-cleaving activity of TelN for at least 4 weeks, greatly simplifying in vitro testing of its activity. This protocol may be extended for functional analysis of other phage and bacterial proteins, particularly DNA-processing enzymes.
    Matched MeSH terms: Telomere/chemistry
  5. Eshkoor SA, Ismail P, Rahman SA, Moin S
    Arh Hig Rada Toksikol, 2011 Dec;62(4):291-8.
    PMID: 22202462 DOI: 10.2478/10004-1254-62-2011-2088
    The aim of our study was to see the effects of GSTP1 polymorphism on biomarkers of ageing, including micronuclei (MN), comet tail length, and relative telomere length in automobile repair workers, who are exposed to a broad spectrum of potential mutagens. The analysis was performed on buccal cells collected from occupationally exposed and non-exposed (control) subjects. Samples were analysed using cytogenetic and molecular methods, including restriction fragment length polymorphism (RFLP), MN test, comet assay, and real-time PCR. The results confirmed the DNA damaging effects of substances used in the mechanical workshops, but did not confirm the influence of GSTP1 gene polymorphism on DNA damage. However, further studies on both occupationally exposed and control populations are needed to understand the relationship between GSTP1 polymorphism and genome damage.
    Matched MeSH terms: Telomere Homeostasis
  6. Looi LM, Cheah PL, Ng MH, Yip CH, Mun KS, Rahman NA
    Asian Pac J Cancer Prev, 2010;11(3):713-6.
    PMID: 21039041
    A study was initiated to explore possible differences in handling telomere attrition in the most common lignant and benign tumours of the breast in Malaysian women. Infiltrating ductal carcinoma (IDC) and fibroadenoma (FA) represented the malignant and benign prototypes respectively. 29 IDC, 28 FA and 22 benign non-lesional control (BNL) breast tissue samples were analysed for telomerase activation using a Telomerase PCR ELISA kit (Boehringer Mannheim). In addition, 23 IDC, 12 FA and 14 BNL were subjected to telomere length determination with a TeloTAGGG Telomere Length Assay Kit (Roche Diagnostic GmbH, Germany), following digestion of genomic DNA by frequently cutting restriction enzymes RsaI and HinfI. Mean telomerase activity in IDC (A450nm=0.3338), but not FA (A450nm=0.0003) was significantly raised (p<0.05) compared with BNL (A450nm=0.0031). Similarly IDC (1.2 kb), but not FA (2.2 kb), showed significant telomere shortening (p<0.05) relative to BNL (2.9 kb). The findings imply that telomere attrition and telomerase activation differ between malignant and benign tumours of the breast and may be important for targeted therapy.
    Matched MeSH terms: Telomere/genetics*
  7. Sasidharan S, Jothy SL, Kavitha N, Chen Y, Kanwar JR
    Asian Pac J Cancer Prev, 2015;16(18):8671.
    PMID: 26745135
    Matched MeSH terms: Telomere/genetics; Telomere/chemistry*
  8. Naing C, Aung K, Lai PK, Mak JW
    BMC Cancer, 2017 01 05;17(1):24.
    PMID: 28056862 DOI: 10.1186/s12885-016-2997-3
    BACKGROUND: Human chromosomes are capped and stabilized by telomeres. Telomere length regulates a 'cellular mitotic clock' that defines the number of cell divisions and hence, cellular life span. This study aimed to synthesize the evidence on the association between peripheral blood leucocytes (PBL) telomere length and the risk of colorectal cancer (CRC).

    METHODS: We searched relevant studies in electronic databases. When two or more observational studies reported the same outcome measures, we performed pooled analysis. All the analyses were performed on PBL using PCR. The odds ratio (OR) and its 95% confidence interval (CI) were used to assess the strength of association.

    RESULTS: Seven studies (with 8 datasets) were included in this meta-analysis; 3 prospective studies, 3 retrospective studies and 1 study with a separate prospective and retrospective designs. The pooled analysis of 4 prospective studies (summary OR 1.01, 95% CI: 0.77-1.34, I (2):30%) and 4 retrospective studies (summary OR 1.65, 95% CI: 0.96-2.83, I (2):96%) showed no relationship between PBL telomere length and the CRC risk. A subgroup analysis of 2 prospective studies exclusively on females also showed no association between PBL telomere length and the CRC risk (summary OR, 1.17, 95% CI:0.72-1.91, I (2):57%).

    CONCLUSION: The current analysis is insufficient to provide evidence on the relationship between PBL telomere length and the risk of CRC. Findings suggest that there may be a complex relationship between PBL telomere length and the CRC risk or discrepancy between genetics, age of patients and clinical studies. Future well powered, large prospective studies on the relationship between telomere length and the risk of CRC, and the investigations of the biologic mechanisms are recommended.

    Matched MeSH terms: Telomere/pathology*
  9. Eshkoor S, Ismail P, Rahman S, Moin S, Adon M
    Balkan J. Med. Genet., 2013 Dec;16(2):45-52.
    PMID: 24778563 DOI: 10.2478/bjmg-2013-0031
    The ageing process is influenced by many internal and external factors. The toxic substances in the environment can cause genomic damages to cells, which increase the risk of early ageing. Furthermore, the cytochrome P450 1A2 (CYP1A2) gene polymorphism is a susceptibility factor and may enhance the risk of DNA damage in cells. The current study was carried out to show whether occupational exposure could cause genotoxicity in cells carrying the CYP1A2 gene polymorphism, thus enhancing the likelihood of early ageing. This study was conducted on mechanical workshop workers and a control group by collecting buccal cells from their mouths. Restriction fragment length polymorphism-polymerase chain reaction (RFLP-PCR) was used to identify the CYP1A2 gene polymorphism in the cells. In addition, three extra methods including micronuclei (MN) test, comet assay and real-time PCR (RT-PCR) were applied to determine the effects of gene polymorphisms on DNA damage and ageing from occupational exposure. The results showed that DNA damage in the cells carrying the mutated genotype was higher than the wild genotype. In addition, the difference in MN frequency (p = 0.001) and relative telomere length (p = 0.002) between workers and controls was significant (p <0.05) in the mutated genotype. The findings indicated a possible protective effect of gene polymorphism against early ageing, which was characterized by lack of a significant influence of CYP1A2 gene polymorphism on genetic material in the subjects (p >0.05). It was concluded that the CYP1A2 gene could be a contributing factor to prevent early ageing from occupational exposure.
    Matched MeSH terms: Telomere
  10. Lew LC, Hor YY, Jaafar MH, Lau ASY, Ong JS, Chuah LO, et al.
    Benef Microbes, 2019 Dec 09;10(8):883-892.
    PMID: 31965837 DOI: 10.3920/BM2019.0058
    This study aimed to evaluate the anti-ageing effects of different strains of lactobacilli putative probiotics on an ageing rat model as induced by D-galactose and a high fat diet. Male Sprague-Dawley rats were fed with high fat diet (54% kcal fat) and injected with D-galactose daily for 12 weeks to induce ageing. The effects of putative probiotic strains on age-related impairment such as telomere length, plasma lipid peroxidation, hepatic 5'adenosine monophosphate-activated protein kinase (AMPK) expression, as well as endurance performance were evaluated. Administration of statin, Lactobacillus plantarum DR7 (LP-DR7), Lactobacillus fermentum DR9 (LF-DR9), and Lactobacillus reuteri 8513d (LR-8513d) significantly reduced the shortening of telomere and increased the expression of AMPK subunit-α1 (P<0.05). Plasma lipid peroxidation was lower (P<0.05) in groups administered with statin and LF-DR9 as compared to the control. AMPK subunit-α2 was elevated in rats administered with LP-DR7 as compared to the control (P<0.05). Using an in vivo ageing rat model, the current study has illustrated the potentials of lactobacilli putative probiotics in alleviation of age-related impairment in a strain-dependent manner.
    Matched MeSH terms: Telomere Shortening/drug effects*
  11. Aye Aye Wynn, Nang Khin Mya
    MyJurnal
    Telomeres are specialized DNA complexes found at the end of all chromosomes. Human, as a member of eukaryotic cells, requires telomeres to maintain the length and the stability of chromosomes. Telomeres lose their non-coding DNA sequence to protect the genetic information on the chromosomes. Shortening of telomeres occurs in most somatic cells after sufficient cell division in a human lifetime. Normal haemopoietic cells or stem cells possess telomerase enzyme to restore telomeres and allow further replication. Telomere dysfunction is the origin of several degenerative disorders and also predispose to cancer. Roles of telomere in carcinogenesis and ageing related disorders are reviewed.
    Matched MeSH terms: Telomere; Telomere Shortening
  12. Wong SK, Ima-Nirwana S, Chin KY
    Bosn J Basic Med Sci, 2020 Nov 02;20(4):423-429.
    PMID: 32156247 DOI: 10.17305/bjbms.2020.4664
    Telomeres are repetitive DNA sequences located at the end of chromosomes that serve as a protective barrier against chromosomal deterioration during cell division. Approximately 50-200 base pairs of nucleotides are lost per cell division, and new repetitive nucleotides are added by the enzyme telomerase, allowing telomere maintenance. Telomere shortening has been proposed as an indicator for biological aging, but its relationship with age-related osteoporosis is ambiguous. We summarize the current evidence on the relationship between telomere length and bone health in experimental and epidemiological studies, which serve as a scientific reference for the development of novel diagnostic markers of osteoporosis or novel therapeutics targeting telomere and telomerase of bone cells to treat osteoporosis.
    Matched MeSH terms: Telomere/ultrastructure*; Telomere Shortening*
  13. Campa D, Barrdahl M, Santoro A, Severi G, Baglietto L, Omichessan H, et al.
    Breast Cancer Res, 2018 04 17;20(1):29.
    PMID: 29665866 DOI: 10.1186/s13058-018-0955-5
    BACKGROUND: Leukocyte telomere length (LTL) and mitochondrial genome (mtDNA) copy number and deletions have been proposed as risk markers for various cancer types, including breast cancer (BC).

    METHODS: To gain a more comprehensive picture on how these markers can modulate BC risk, alone or in conjunction, we performed simultaneous measurements of LTL and mtDNA copy number in up to 570 BC cases and 538 controls from the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort. As a first step, we measured LTL and mtDNA copy number in 96 individuals for which a blood sample had been collected twice with an interval of 15 years.

    RESULTS: According to the intraclass correlation (ICC), we found very good stability over the time period for both measurements, with ICCs of 0.63 for LTL and 0.60 for mtDNA copy number. In the analysis of the entire study sample, we observed that longer LTL was strongly associated with increased risk of BC (OR 2.71, 95% CI 1.58-4.65, p = 3.07 × 10- 4 for highest vs. lowest quartile; OR 3.20, 95% CI 1.57-6.55, p = 1.41 × 10- 3 as a continuous variable). We did not find any association between mtDNA copy number and BC risk; however, when considering only the functional copies, we observed an increased risk of developing estrogen receptor-positive BC (OR 2.47, 95% CI 1.05-5.80, p = 0.04 for highest vs. lowest quartile).

    CONCLUSIONS: We observed a very good correlation between the markers over a period of 15 years. We confirm a role of LTL in BC carcinogenesis and suggest an effect of mtDNA copy number on BC risk.

    Matched MeSH terms: Telomere/genetics; Telomere Homeostasis/genetics*
  14. Sarina Sulong, Ahmad Syibli Othman, Zaidatul Shakila Mohamad Ashari
    MyJurnal
    The telomere and telomerase hypothesis of aging and cancer is based on the findings that most human tumors have telomerase activity while almost all normal human somatic cells do not. Telomeres are nucleoprotein structure that located 100-300 kb from the end of linear eukaryotic chromosomes (Blackburn et al, 2001; Yoo & Robinson, 2000). Human telomeres consist of thousand repetitive sequences TTAGGG with ranging from 5 to 20 kb (Figure 1) (Martin, 2002). In human cell, there are 92 telomeres which have several functions including protecting chromosome ends, to maintain chromosome stability, serve as an attachment point to the nuclear matrix and also involve in the cell replication.
    Matched MeSH terms: Telomere
  15. Watihayati Mohd Shamshudin, Nazihah Mohd Yunus, Sarina Sulong
    MyJurnal
    Telomerase has become important in molecular genetics since its discovery in 1984. The study of telomere in ciliate Tetrahymena thermophilia since 4 decades ago has led to the discovery of telomerase that was discovered by Elizabeth Blackburn and her postgraduate student, Carol Widney Greider in 1984. Later in 2009, Jack William Szostak together with Greider and Blackburn were awarded the Nobel Prize in Physiology or Medicine for their discovery. (Copied from article).
    Matched MeSH terms: Telomere
  16. Ariffin H, Azanan MS, Abd Ghafar SS, Oh L, Lau KH, Thirunavakarasu T, et al.
    Cancer, 2017 Nov 01;123(21):4207-4214.
    PMID: 28654149 DOI: 10.1002/cncr.30857
    BACKGROUND: Large epidemiologic studies have reported the premature onset of age-related conditions, such as ischemic heart disease and diabetes mellitus, in childhood cancer survivors, decades earlier than in their peers. The authors investigated whether young adult survivors of childhood acute lymphoblastic leukemia (ALL) have a biologic phenotype of cellular ageing and chronic inflammation.

    METHODS: Plasma inflammatory cytokines were measured using a cytometric bead array in 87 asymptomatic young adult survivors of childhood ALL (median age, 25 years; age range, 18-35 years) who attended annual follow-up clinic and compared with healthy, age-matched and sex-matched controls. Leukocyte telomere length (LTL) was measured using Southern blot analysis.

    RESULTS: Survivors had significant elevation of plasma interleukin-2 (IL-2), IL-10, IL-17a, and high-sensitivity C-reactive protein levels (all P 0.8 mg/dL) was related to increased odds of having metabolic syndrome (odds ratio, 7.256; 95% confidence interval, 1.501-35.074). Survivors also had significantly shorter LTL compared with controls (median, 9866 vs 10,392 base pairs; P = .021). Compared with published data, LTL in survivors was similar to that in healthy individuals aged 20 years older. Survivors who received cranial irradiation had shorter LTL compared with those who had not (P = .013).

    CONCLUSIONS: Asymptomatic young adult survivors of childhood ALL demonstrate a biologic profile of chronic inflammation and telomere attrition, consistent with an early onset of cellular processes that drive accelerated aging. These processes may explain the premature development of age-related chronic conditions in childhood cancer survivors. Understanding their molecular basis may facilitate targeted interventions to disrupt the accelerated aging process and its long-term impact on overall health. Cancer 2017;123:4207-4214. © 2017 American Cancer Society.

    Matched MeSH terms: Telomere/radiation effects; Telomere Shortening*
  17. Samad MA, Saiman MZ, Abdul Majid N, Karsani SA, Yaacob JS
    Cell Biochem Biophys, 2024 Mar;82(1):153-173.
    PMID: 38198024 DOI: 10.1007/s12013-023-01210-8
    Colorectal cancer (CRC) is the most common cancer in both men and women and is associated with increased telomerase levels and activity. The potential downstream effects of TERT and/or TERC downregulation by berberine (a telomerase inhibitor) or RNA interference (RNAi) on various target RNAs, proteins, relative telomerase activity (RTA), relative telomere length (RTL), hydrogen peroxide concentration [H2O2], percentage of cell cycle distribution, cell size and granularity as well as cellular metabolites were explored in HCT 116 cell line. Knockdown of TERT decreased TERC. The downregulation of TERT and/or TERC caused increment of [H2O2], G0/G1 phase arrest in addition to decreased S and G2/M phases, as well as diminished cell size. RTL was later reduced as a result of TERT, TERT and/or TERC downregulation which decreased RTA. It was discovered that xanthine oxidase (XO) was significantly and positively correlated at FDR-adjusted p value 
    Matched MeSH terms: Telomere/metabolism
  18. Machiela MJ, Hofmann JN, Carreras-Torres R, Brown KM, Johansson M, Wang Z, et al.
    Eur Urol, 2017 Nov;72(5):747-754.
    PMID: 28797570 DOI: 10.1016/j.eururo.2017.07.015
    BACKGROUND: Relative telomere length in peripheral blood leukocytes has been evaluated as a potential biomarker for renal cell carcinoma (RCC) risk in several studies, with conflicting findings.

    OBJECTIVE: We performed an analysis of genetic variants associated with leukocyte telomere length to assess the relationship between telomere length and RCC risk using Mendelian randomization, an approach unaffected by biases from temporal variability and reverse causation that might have affected earlier investigations.

    DESIGN, SETTING, AND PARTICIPANTS: Genotypes from nine telomere length-associated variants for 10 784 cases and 20 406 cancer-free controls from six genome-wide association studies (GWAS) of RCC were aggregated into a weighted genetic risk score (GRS) predictive of leukocyte telomere length.

    OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Odds ratios (ORs) relating the GRS and RCC risk were computed in individual GWAS datasets and combined by meta-analysis.

    RESULTS AND LIMITATIONS: Longer genetically inferred telomere length was associated with an increased risk of RCC (OR=2.07 per predicted kilobase increase, 95% confidence interval [CI]:=1.70-2.53, p<0.0001). As a sensitivity analysis, we excluded two telomere length variants in linkage disequilibrium (R2>0.5) with GWAS-identified RCC risk variants (rs10936599 and rs9420907) from the telomere length GRS; despite this exclusion, a statistically significant association between the GRS and RCC risk persisted (OR=1.73, 95% CI=1.36-2.21, p<0.0001). Exploratory analyses for individual histologic subtypes suggested comparable associations with the telomere length GRS for clear cell (N=5573, OR=1.93, 95% CI=1.50-2.49, p<0.0001), papillary (N=573, OR=1.96, 95% CI=1.01-3.81, p=0.046), and chromophobe RCC (N=203, OR=2.37, 95% CI=0.78-7.17, p=0.13).

    CONCLUSIONS: Our investigation adds to the growing body of evidence indicating some aspect of longer telomere length is important for RCC risk.

    PATIENT SUMMARY: Telomeres are segments of DNA at chromosome ends that maintain chromosomal stability. Our study investigated the relationship between genetic variants associated with telomere length and renal cell carcinoma risk. We found evidence suggesting individuals with inherited predisposition to longer telomere length are at increased risk of developing renal cell carcinoma.

    Matched MeSH terms: Telomere/genetics*; Telomere/pathology; Telomere Homeostasis*
  19. Mabruk MJ, O'Flatharta C
    Expert Rev Mol Diagn, 2005 Nov;5(6):907-16.
    PMID: 16255632
    A number of methods exist to detect levels of telomerase activity and the presence of telomerase subunits in a variety of tissues. As telomerase activation seems to be an important step in tumorigenesis, accurate detection of the presence and activity of the enzyme and its subunits is vital. The original method of detecting telomerase activity was developed by Kim and coworkers in 1994, and was termed the telomeric repeat amplification protocol. This assay led to a staggering increase in the number of telomerase-associated publications in scientific journals (85 publications from 1974-1994, 5063 publications from 1994-2004). A number of methods have been described to detect telomeres and to measure their length, with the standard measurement of telomere length performed using a modification of the Southern blot protocol. RNA in situ hybridization can be performed to detect levels of the RNA component of telomerase, and standard in situ hybridization and immunohistochemistry can be applied to examine expression levels and localization of the catalytic subunit of the enzyme. Reverse transcriptase PCR has also been applied to assess expression levels of the telomerase components in various tissues. This review provides a synopsis of telomeres, telomerase, telomerase and cancer, and finally, methods for the detection of telomerase in cancer.
    Matched MeSH terms: Telomere/metabolism
  20. Lee JW, Ong EBB
    Front Cell Dev Biol, 2020;8:619126.
    PMID: 33511130 DOI: 10.3389/fcell.2020.619126
    Aging is a complex biological process that occurs in all living organisms. Aging is initiated by the gradual accumulation of biomolecular damage in cells leading to the loss of cellular function and ultimately death. Cellular senescence is one such pathway that leads to aging. The accumulation of nucleic acid damage and genetic alterations that activate permanent cell-cycle arrest triggers the process of senescence. Cellular senescence can result from telomere erosion and ribosomal DNA instability. In this review, we summarize the molecular mechanisms of telomere length homeostasis and ribosomal DNA stability, and describe how these mechanisms are linked to cellular senescence and longevity through lessons learned from budding yeast.
    Matched MeSH terms: Telomere; Telomere Homeostasis
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