Difference In Telomere Length Research Articles

Erratum to: Oceanic residents, neritic migrants: a possible mechanism underlying foraging dichotomy in adult female loggerhead turtles (Caretta caretta)

To reveal the mechanism underlying intrapopulation variation in the use of feeding habitats (oceanic vs. neritic) by adult female loggerhead turtles (Caretta caretta), we compared telomere length in the epidermis (a proxy for age) between oceanic- and neritic-foraging recruits (first-time nesters). Based on egg-yolk stable isotope ratios, recruits at Yakushima Island, Japan, were clearly divided into small oceanic planktivores and large neritic benthivores. There were no significant differences in telomere length between oceanic and neritic foragers, suggesting that they start reproduction at similar ages. Turtles that experienced faster growing conditions during their oceanic early lives may achieve sexual maturity there, while others may move from oceanic areas into neritic habitats, switching diets from nutrient-poor macroplankton to nutrient-rich benthic fauna in order to compensate for their earlier slow growth rate and continue their sexual development, reaching maturity in neritic waters.

Alterations of telomere length in human brain tumors

Telomeres at the ends of human chromosomes consist of tandem hexametric (TTAGGG)n repeats, which protect them from degradation. At each cycle of cell division, most normal somatic cells lose approximately 50-100bp of the terminal telomeric repeat DNA. Precise prediction of growth and estimation of the malignant potential of brain tumors require additional markers. DNA extraction was performed from the 51 frozen tissues, and a non-radioactive chemiluminescent assay was used for Southern blotting. One sample t-test shows highly significant difference in telomere length in meningioma and astrocytoma with normal range. According to our results, higher grades of meningioma and astrocytoma tumors show more heterogeneity in telomere length, and also it seems shortening process of telomeres is an early event in brain tumors.

Proximate determinants of telomere length in sand lizards ( Lacerta agilis )

Telomeres are repeat sequences of non-coding DNA that cap the ends of chromosomes and contribute to their stability and the genomic integrity of cells. In evolutionary ecology, the main research target regarding these genomic structures has been their role in ageing and as a potential index of age. However, research on humans shows that a number of traits contribute to among-individual differences in telomere length, in particular traits enhancing cell division and genetic erosion, such as levels of free radicals and stress. In lizards, tail loss owing to predation attempts results in a stress-induced shift to a more cryptic lifestyle. In sand lizard (Lacerta agilis) males, telomere length was compromised by tail regrowth in a body size-related manner, so that small males, which already exhibit more cryptic mating tactics, were less affected than larger males. Tail regrowth just fell short of having a significant relationship with telomere length in females, and so did age in males. In females, there was a significant positive relationship between age and telomere length. We conclude that the proximate effect of compromised antipredation and its associated stress seems to have a more pronounced effect in males than in females and that age-associated telomere dynamics differ between the sexes.

Do US Black Women Experience Stress-Related Accelerated Biological Aging?: A Novel Theory and First Population-Based Test of Black-White Differences in Telomere Length.

We hypothesize that black women experience accelerated biological aging in response to repeated or prolonged adaptation to subjective and objective stressors. Drawing on stress physiology and ethnographic, social science, and public health literature, we lay out the rationale for this hypothesis. We also perform a first population-based test of its plausibility, focusing on telomere length, a biomeasure of aging that may be shortened by stressors. Analyzing data from the Study of Women's Health Across the Nation (SWAN), we estimate that at ages 49-55, black women are 7.5 years biologically "older" than white women. Indicators of perceived stress and poverty account for 27% of this difference. Data limitations preclude assessing objective stressors and also result in imprecise estimates, limiting our ability to draw firm inferences. Further investigation of black-white differences in telomere length using large-population-based samples of broad age range and with detailed measures of environmental stressors is merited.

Telomere length, molecular cytogenetic findings, and immunophenotypic features in previously untreated patients with B-chronic lymphocytic leukemia

Telomere length was evaluated by terminal repeat fragment method in 66 previously untreated patients with B-chronic lymphocytic leukemia (B-CLL) to ascertain whether telomere shortening was associated with genomic aberrations, immunoglobulin variable heavy chain (IgVH) mutational status, CD38 and ZAP-70 expression, and telomerase activity. Chromosomal aberrations were present in peripheral blood cells of 73% patients (48/66), no difference in telomere length between patients with good and intermediate prognosis according to cytogenetics was found. Association between telomere length and IgVH mutational status, ZAP-70 and CD38 expression was proved as significantly shorter telomeres in patients with unmutated IgVH status (p=0.01) and ZAP-70 positivity (p=0.01) and CD38 positivity (p=0.05) were detected. Telomerase activity was positive in 11 patients out of 21 examined, correlation between telomere length and telomerase activity was found (p=0.05). Telomere length and telomerase activity in combination with other prognostic parameters complete the risk profile of B-CLL patients and might serve for an easy decision on optimal treatment strategy. B-chronic lymphocytic leukemia, telomere length, telomerase activity, chromosomal aberrations, prognosis.

Telomere length in human adults and high level natural background radiation.

BackgroundTelomere length is considered as a biomarker of aging, stress, cancer. It has been associated with many chronic diseases such as hypertension and diabetes. Although, telomere shortening due to ionizing radiation has been reported in vitro, no in vivo data is available on natural background radiation and its effect on telomere length.Methodology/Principal FindingsThe present investigation is an attempt to determine the telomere length among human adults residing in high level natural radiation areas (HLNRA) and the adjacent normal level radiation areas (NLNRA) of Kerala coast in Southwest India. Genomic DNA was isolated from the peripheral blood mononuclear cells of 310 individuals (HLNRA: N = 233 and NLNRA: N = 77). Telomere length was determined using real time q-PCR. Both telomere (T) and single copy gene (S) specific primers were used to calculate the relative T/S and expressed as the relative telomere length. The telomere length was determined to be 1.22±0.15, 1.12±0.15, 1.08±0.08, 1.12±0.11, respectively, among the four dose groups (≤1.50, 1.51–3.00, 3.01–5.00 and >5.00 mGy per year), which did not show any dose response. The results suggested that the high level natural chronic radiation did not have significant effect on telomere length among young adult population living in HLNRA, which is indicative of better repair of telomeric ends. No significant difference in telomere length was observed between male and female individuals. In the present investigation, although the determination of telomere length was studied among the adults with an age group between 18 to 40 years (mean maternal age: 26.10±4.49), a negative correlation was observed with respect to age. However, inter-individual variation was (0.81–1.68) was clearly observed.Conclusions/SignificanceIn this preliminary investigation, we conclude that elevated level of natural background radiation has no significant effect on telomere length among the adult population residing in HLNRAs of Kerala coast. To our knowledge, this is the first report from HLNRAs of the world where telomere length was determined on human adults. However, more samples from each background dose group and samples from older population need to be studied to derive firm conclusions.

Abstract C27: Evaluation of the telomere QPCR assay for use in gauging the effect of storage conditions on telomere length

Abstract Telomere length has been reported as potentially biomarker and prognostic indicator in cancer. Our goal was to evaluate whether DNA storage/handling or sample source would result in fragmented telomere DNA using an established QPCR-based telomere assay that quantifies the length of telomeres (Cawthon 2002) Because the effect of storage conditions on telomere length has not been thoroughly evaluated, we were concerned that the QPCR could misclassify telomere length and lead to misleading epidemiological results. Genomic DNA samples for this preliminary study were gathered from either The Nurses Health Study, healthy volunteers, the MDA-MB-231 cell line (human breast cancer), and a commercial source (Promega). To create a model system of degraded DNA, the DNA were either subjected to multiple freeze thaws (FT, <20), Covaris S2 sonication (<6 Cycles; intensity 5/8, 200/500 bursts), or DNase I treatment (<1 U/ 1 ug). The QPCR assay modified the reactants, parameters, and the thermocycler. By examining the distribution of telomeric PCR amplicons on the Agilent Bioanalyzer 2100 based upon their relative quantity and size, we sought to analyze the effects of damaging measures. Ct measurements provided data as to the relative number of telomeric targets present in the respective samples and melt peak analyses (MPA) identified the unique amplicon Tm compositions. Due to the repetitive nature of the telomeric sequence, we expected to see discrete amplicon sizes starting at 76 Bp reaching over hundreds of Bps. Bioanalyzer electropherograms indicated that eight to twelve major products of ∼8 Bp iterations are commonly produced up to 150 Bp with some minor products <200 Bp. A primer generated amplicon at ∼84 Bp, although not always present, confounded the analyses. Interestingly, MPA showed a single melt peak at ∼79C for all telomeric amplicons; the aberrant peak had a lesser Tm of ∼78C. Ct data do suggest that although the telomeres are sensitive to enzymatic assault (two–three log reduction), as many as 20 FTs and extensive sonication seem not to degrade the telomere (no Ct change). Ct values indicated that differences in telomere length exist between persons (range: 16–19); the MDA-MB-231 cell line had the shortest telomere length (Ct 22). However, neither individual samples nor samples subjected to DNase I digestion were significantly differentiated via end-point analysis on the Bioanalyzer. In summary, under the current experimental conditions, the QPCR assay does not generate sufficient variable length amplicons as to present a measurable metric using the Bioanalyzer. Elevated Ct values do seem to correlate with the presence of degraded DNA, and therefore suggest under the conditions used multiple FTs and sonication do not damage the telomeric sequences. However this assay design cannot currently determine the relative contribution of full length vs. degraded telomeric sequence to the Ct value. Further investigation is warranted before this assay becomes clinically diagnostic or prognostic. Citation Information: Mol Cancer Ther 2009;8(12 Suppl):C27.

Telomere shortening and chromosomal instability in myelodysplastic syndromes

Telomere shortening and chromosomal instability are believed to play an important role in the development of myeloid neoplasia. So far, published data are only available on the average telomere length in myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML), but not on the telomere length of individual chromosomes. We used a new technique, telomere/centromere-fluorescence in situ hybridization (T/C-FISH), which combines fluorescence R-banding and FISH using a probe against the telomere repeats to measure the telomere length of each chromosome arm in 78 patients with MDS. In line with the previous results, patients with MDS showed significantly shorter telomeres than those of healthy controls. Telomere lengths did not differ significantly between distinct morphological subtypes of MDS. However, there was a significant difference in telomere length between patients with an isolated monosomy 7 and patients with a normal karyotype (P < 0.05). Notably, patients with an isolated monosomy 7 showed significantly longer telomeres than patients with a normal karyotype in many chromosome arms, among them 7p and 7q. Neo-telomeres were found in two patients with a complex karyotype, in one case at the fusion site of a dic(14;20). Normal and aberrant metaphases of the same patient did not differ in telomere length, thus indicating to telomere shortening as a basic mechanism affecting all hematopoietic cells in patients with MDS. In some MDS subtypes, like MDS with isolated monosomy 7, telomeres may be stabilized and even increase in length because of the activation of telomerase or alternative mechanisms.

The Extent in Telomere Attrition and the Number of Affected Leukocyte Subsets Distinguishes Patients with Different Myeloproliferative Neoplasms (MPN).

Abstract 1913Poster Board I-936 Background:Myeloproliferative neoplasms (MPN) are clonal disorders with an origin of the disease in a hematopoietic stem or progenitor cell. Except for chronic myeloid leukemia (CML), the diagnosis for Philadelphia-chromosome negative (Ph-neg.) MPN is less straightforward. Although many patients with a Ph-neg. MPN can be identified by mutations in JAK2 and/or TET2, the categorization into primary or secondary cythosis or specifically into polycythemia vera (PV), essential thrombocythemia (ET) and primary myelofibrosis (PMF) can be difficult. Since telomeres can be used to estimate the mitotic history of cells, our aims were to evaluate 1) whether the telomere length can be used to distinguish clonal from polyclonal hematopoiesis, 2) whether telomere attrition correlates to the mutational status of JAK2 and 3) whether the extent of telomere shortening in different subsets of leukocytes can point to the originating level of the hematopoietic stem or progenitor cell. Patients and Methods:So far, 32 patients with Ph-neg. MPN diagnosed according to WHO criteria (range: 32 – 85 years; PV: n=19, ET n=5, PMF n=8; JAK2V617F positive n=22, JAK2V617F negative n=16) and 11 patients with secondary erythrocythosis (range 39 – 61 years) were included in this study. 400 healthy individuals (range 0-102 years) served as controls. After informed consent peripheral blood was taken from the patients to measure the telomere length in subsets of leukocytes by automated multicolor flow-FISH. In order to correct for the age-dependent decline in telomere length, telomere length differences to the 50th percentile of the healthy cohort (DeltaTel) were calculated. Telomere length values below the 10th percentile of those from healthy donors were considered as substantially affected by telomere attrition. The mutational status of the JAK2V617F was assessed by allele-specific real time quantitative PCR. Results:The mean telomere length in granulocytes from patients with MPN was considerably shorter compared to healthy controls (mean ± STD DeltaTel: 2.73kb ± 1.20kb), whereas there was no remarkable difference in lymphocytes (0.70kb ± 0.81kb). Furthermore, we found significant DeltaTel between granulocytes from patients with MPN and with secondary erythrocythosis (mean ± STD: 2.73kb ± 1.20kb vs. 1.66kb ± 0.894kb, p<0.0001). Regarding the JAK2V617F mutational status we found no difference for the average DeltaTel (mean ± STD: 2.35kb ± 1.25kb (JAKV617F+), 2.28kb ± 1.12kb (JAKV617F-), p=0.84). Most interestingly, there was a clear difference in the average DeltaTel in granulocytes from patients with different types of MPN (ANOVA p=0.017). The most striking DeltaTel was seen between patients with PMF and patients with PV and ET (PMF: 3.72kb ± 0.30kb, PV and ET: 2.40kb ± 1.18kb, p=0.005). In addition, in patients with PMF most subsets of leukocytes demonstrated substantial telomere length differences compared to healthy controls (Granulocytes: 2.06kb ± 0.55kb, p=0.0001, T-cells: 0.84kb ± 1.07kb, p=0.016, B-cells: 1.62kb ± 1.29kb, p=0.0001, NK-cells: 0.95kb ± 1.49kb, p=0.039), whereas in patients with ET, except for the granulocyte subset, no significant DeltaTel values were detected (Granulocytes: 1.01kb ± 0.856kb, p=0.014, T-cells: -0.435kb ± 0.723, p=0.34, B-cells: 0.26kb ± 1.00kb, p=0.65, NK-cells: 0.30kb ± 0.86kb, p=0.58). In patients with PV one to three leukocyte subsets showed substantial DeltaTel, but in varying combinations. Conclusion:In our ongoing study we were able to confirm shorter telomeres in granulocytes of MPN patients compared to telomeres in granulocytes of healthy controls and of patients with secondary erythrocythosis. Based on the telomere length attrition patients with a clonal cythosis can be distinguished from such patients with a secondary cythosis, which could help diagnostically in uncertain cases. No correlation was found between the extent of telomere attrition and the JAK2V617F mutational status. The extremely short telomeres found in most subsets of leukocytes from patients with PMF could point to a very early hematopoietic stem cell as the cell of origin, whereas for ET and PV with only one or a few subsets of leukocytes affected by telomere attrition the cell of origin could be a hematopoietic stem cell at a somewhat later stage. Disclosures:No relevant conflicts of interest to declare.

Expression of Telomerase and Telomere Length Are Unaffected by either Age or Limb Regeneration in Danio rerio

BackgroundThe zebrafish is an increasingly popular model for studying many aspects of biology. Recently, ztert, the zebrafish homolog of the mammalian telomerase gene has been cloned and sequenced. In contrast to humans, it has been shown that the zebrafish maintains telomerase activity for much of its adult life and has remarkable regenerative capacity. To date, there has been no longitudinal study to assess whether this retention of telomerase activity equates to the retention of chromosome telomere length through adulthood.Methodology/Principal FindingsWe have systematically analyzed individual organs of zebrafish with regard to both telomere length and telomerase activity at various time points in its adult life. Heart, gills, kidney, spleen, liver, and intestine were evaluated at 3 months, 6 months, 9 months, and 2 years of age by Southern blot analysis. We found that telomeres do not appreciably shorten throughout the lifespan of the zebrafish in any organ. In addition, there was little difference in telomere lengths between organs. Even when cells were under the highest pressure to divide after fin-clipping experiments, telomere length was unaffected. All aged (2 year old) tissues examined also expressed active amounts of telomerase activity as assessed by TRAP assay.Conclusions/SignificanceIn contrast to several other species including humans, the retention of lifelong telomerase and telomeres, as we have reported here, would be necessary in the zebrafish to maintain its tremendous regenerative capacity. The ongoing study of the zebrafish's ability to maintain telomerase activity may be helpful in unraveling the complexity involved in the maintenance (or lack thereof) of telomeres in other species such the mouse or human.

Individual Telomere Lengths in Chronic Myeloid Leukemia

Chronic myeloid leukemia (CML) is a neoplasia characterized by proliferation of a myeloid cell lineage and chromosome translocation t(9;22) (q34;q11.2). As in the case of most cancers, the average telomere length in CML cells is shorter than that in normal blood cells. However, there are currently no data available concerning specific individual telomere length in CML. Here, we studied telomere length on each chromosome arm of CML cells. In situ hybridization with peptide nucleic acid probes was performed on CML cells in metaphase. The fluorescence intensity of each specific telomere was converted into kilobases according to the telomere restriction fragment results for each sample. We found differences in telomere length between short arm ends and long arm ends. We observed recurrent telomere length changes as well as telomere length maintenance and elongation in some individual telomeres. We propose a possible involvement of individual telomere length changes to some chromosomal abnormalities in CML. We suggest that individual telomere length maintenance is chromosome arm-specific associated with leukemia cells.

Telomere length predicts all-cause mortality in patients with type 1 diabetes

Type 1 diabetic patients with diabetic nephropathy have increased mortality and morbidity compared with normoalbuminuric patients. Telomere length in proliferative cells is inversely related to the total number of cell divisions, and therefore to biological age. We aimed to evaluate differences in telomere length in patients with type 1 diabetes with or without diabetic nephropathy; we also evaluated the prognostic value of telomere length. In a prospective follow-up study, 157 type 1 diabetic patients with diabetic nephropathy and a control group of 116 patients with type 1 diabetes and normoalbuminuria were followed for 11.1 years (range 0.2-12.9). Telomere length was measured from DNA samples extracted from white blood cells at baseline. The mean telomere length did not differ between patients with or without diabetic nephropathy, and was similar in men and women, but was inversely correlated with age and systolic blood pressure, p < 0.05. When dividing patients into tertiles after telomere length, 36 (37%) patients died in the tertile with the shortest telomere length, 24 (28%) died in the middle tertile, and 15 (17%) of patients in the tertile with the longest telomere length died, log rank test p = 0.017. After adjustment for traditional risk factors, telomere length was still predictive of all-cause mortality. In patients with type 1 diabetes we found no differences in telomere length between patients with or without diabetic nephropathy. We also found that telomere length was associated with all-cause mortality; however, confirmative studies are needed to verify our findings.

Cellular senescence and longevity of osteophyte‐derived mesenchymal stem cells compared to patient‐matched bone marrow stromal cells

This study aimed to determine the cellular aging of osteophyte-derived mesenchymal cells (oMSCs) in comparison to patient-matched bone marrow stromal cells (bMSCs). Extensive expansion of the cell cultures was performed and early and late passage cells (passages 4 and 9, respectively) were used to study signs of cellular aging, telomere length, telomerase activity, and cell-cycle-related gene expression. Our results showed that cellular aging was more prominent in bMSCs than in oMSCs, and that oMSCs had longer telomere length in late passages compared with bMSCs, although there was no significant difference in telomere lengths in the early passages in either cell type. Telomerase activity was detectable only in early passage oMSCs and not in bMSCs. In osteophyte tissues telomerase-positive cells were found to be located perivascularly and were Stro-1 positive. Fifteen cell-cycle regulator genes were investigated and only three genes (APC, CCND2, and BMP2) were differentially expressed between bMSC and oMSC. Our results indicate that oMSCs retain a level of telomerase activity in vitro, which may account for the relatively greater longevity of these cells, compared with bMSCs, by preventing replicative senescence.

Correlations of telomere length changing and pathogeny of keratoconus

To study telomere length, senescence-associated-beta-galactosidase (SA-beta-galactosidase) and senescence marker protein-30 (SMP-30) in the stromal cells of keratoconus or normal corneas respectively, aiming finding the association of these indexes with the phenotype of keratoconus. Experiment research. 37 keratoconus lesions corneas were removed from 32 keratoconus patients who were operated in Shangdong Eye Institute between January 2006 and December 2006, and 20 normal corneas were collected from eye bank. The keratoconus corneas ages were from 13 to 34 years [mean ages (19 + or - 5) years] and the control group consists of 20 normal corneas donor ages from 9 to 30 years [mean ages (19 + or - 4) years]. And there was no statistical difference of ages between keratoconus and normal corneas. Southern blot method was utilized to detect telomere length of genomic DNA. SA-beta-galactosidase was detected by 5-bromo-4-chloro-3-indolyl-beta-D-galactopyranoside (X-Gal) staining method respectively in keratoconus and normal corneas. Isolated mRNA from keratoconus and normal corneas were reverse-transcribed to cDNA and SMP-30 was detected using PCR with specific primers (sense: 5' ccg tgg atg cct ttg act at 3'; anti-sense: 5' caa ctt cat gc tgct ttg ga 3'). To compare normal corneas and keratoconus corneas by histopathological study. Statistical analysis by t test. The telomere length in stromal cells in keratoconus corneas were from 10.29 to 14.12 kb, mean (11.54 + or - 1.41) kb, while that of normal corneas were from 12.64 to 15.32 kb, mean (13.45 + or - 0.99) kb. The difference of telomere length in stromal cells of keratoconus and normal corneas reached a statistical significant level (t = 4.753, P < 0.05). That means the telomere length of keratoconus stroma was shorter than that of normal corneal stroma. Light microscopy revealed that collagen fibers in keratoconus corneal stroma were arranged in an irregular manner. Cells density in keratoconus stroma appeared lower than in normal ones but the decrease was not significant. The staining of SA-beta-galactosidase in the keratoconus section was evident, but there was no staining in the normal corneas. SMP-30 was not detectable with RT-PCR method in either keratoconus or normal corneas. Telomeres in the keratoconus stromas manifest higher SA-beta-galactosidase than control, implying that improper senescence might be involved in pathogenesis of keratoconus.

Cellular senescence of white blood cells in very long-term survivors after allogeneic hematopoietic stem cell transplantation: the role of chronic graft-versus-host disease and female donor sex

AbstractIn this single-center, cross-sectional study, we evaluated 44 very long-term survivors with a median follow-up of 17.5 years (range, 11-26 years) after hematopoietic stem cell transplantation. We assessed the telomere length difference in human leukocyte antigen-identical donor and recipient sibling pairs and searched for its relationship with clinical factors. The telomere length (in kb, mean ± SD) was significantly shorter in all recipient blood cells compared with their donors' blood cells (P < .01): granulocytes (6.5 ± 0.9 vs 7.1 ± 0.9), naive/memory T cells (5.7 ± 1.2 vs 6.6 ± 1.2; 5.2 ± 1.0 vs 5.7 ± 0.9), B cells (7.1 ± 1.1 vs 7.8 ± 1.1), and natural killer/natural killer T cells (4.8 ± 1.0 vs 5.6 ± 1.3). Chronic graft-versus-host disease (P < .04) and a female donor (P < .04) were associated with a greater difference in telomere length between donor and recipient. Critically short telomeres have been described in degenerative diseases and secondary malignancies. If this hypothesis can be confirmed, identification of recipients at risk for cellular senescence could become part of monitoring long-term survivors after hematopoietic stem cell transplantation.

Race/ethnicity and telomere length in the Multi‐Ethnic Study of Atherosclerosis

Telomere length has emerged as a marker of exposure to oxidative stress and aging. Race/ethnic differences in telomere length have been infrequently investigated. Leukocyte telomere length (LTL) was assessed 981 white, black and Hispanic men and women aged 45-84 years participating in the Multi-Ethnic Study of Atherosclerosis. Direct measurement and questionnaire were used to assess covariates. Linear regression was used to estimate associations of LTL with race/ethnicity and age after adjustment for sex, income, education, smoking, physical activity, diet and body mass index. On average blacks and Hispanics had shorter telomeres than whites [adjusted mean differences (standard error) in T/S ratio compared to whites: -0.041 (0.018) for blacks and -0.044 (0.018) for Hispanics]. Blacks and Hispanics showed greater differences in telomere length associated with age than whites (adjusted mean differences in T/S ratio per 1 year increase in age -0.0018, -0.0047 and -0.0055 in whites, blacks and Hispanics respectively). Differences in age associations were more pronounced and only statistically significant in women. Race/ethnic differences in LTL may reflect the cumulative burden of differential exposure to oxidative stress (and its predictors) over the lifecourse.

Leukocyte telomere shortening in elderly Type2DM patients with previous myocardial infarction

Objective We performed a cross-sectional study to examine the differences in leukocyte telomere length among three groups of subjects: patients with type 2 diabetes mellitus without history of previous myocardial infarction (Type2DM), patients with type 2 diabetes mellitus with evidence of previous myocardial infarction (Type2DM + MI), and healthy control subjects (CTR). The main objective of the present study is to investigate differences in telomere length between the studied groups of subjects, with the aim to clarify if telomere length could be a reliable marker associated with MI in Type2DM patients. Secondary end point is the identification of associations between leukocyte telomere length and selected variables related to glycemic control, pro-inflammatory status and lipidic profile. Research design and methods A total of 272 elderly subjects, 103 Type2DM (mean age 70 ± 4 years, 59% males), 65 Type2DM + MI (mean age 68 ± 7 years, 68% males), and 104 CTR (mean age 69 ± 7 years, 50% males) were studied. Telomere length, defined as T/S (Telomere-Single copy gene ratio), was determined in leukocytes by quantitative real-time polymerase chain reaction (real-time PCR)-based assay. Moreover, we assessed: (1) high sensitive C reactive protein (hsCRP), fibrinogen and plasminogen-activator inibitor-1 (PAI-1) as inflammatory markers; (2) fasting glucose, insulin, glycated haemoglobin (HbA1C) and waist-to-hip ratio as markers of glycemic control; (3) total-cholesterol, HDL-cholesterol and triglycerides as markers of lipidic profile, in all sample population. The use of statins and sulfonylurea, as well as the presence of some relevant diabetes complications (nephropathy and retinopathy) were also assessed. Conclusion Type2DM + MI elderly patients have leukocyte telomere lengths shorter than those of Type2DM (without MI) and healthy CTR. Moreover, glucose, HbA1C and waist-to-hip ratio, variables related to glycemic control, showed a significant inverse correlation with leukocyte telomeres length.

Alternative lengthening of telomeres frequently occurs in mismatch repair system‐deficient gastric carcinoma

Maintenance of telomeric ends by the telomerase ribonucleoprotein complex or the telomerase-independent alternative lengthening of telomeres is necessary for the immortalization of human cells. The significance of alternative lengthening of telomeres has been suggested in DNA mismatch repair system-deficient cells; however, much remains unknown in human malignancies. In this study, we investigated the telomere maintenance mechanism in gastric carcinoma. In formalin-fixed and paraffin-embedded sections of the high frequency of microsatellite instability (MSI-H) and non-MSI-H gastric carcinomas, there was no difference in telomere length monitored by telomere intensity ratio using telomere-fluorescent in situ hybridization. Immunoreactivity of hTERT, the catalytic subunit of telomerase, was detected in 48% of MSI-H gastric carcinomas. The frequency was significantly lower than that in non-MSI-H gastric carcinomas (86%, P = 0.02). Conversely, the number of the alternative lengthening of telomeres-associated promyelocytic leukemia bodies (APBs) detected by combined promyelocytic leukemia immunofluorescence and telomere-fluorescent in situ hybridization was statistically higher (57%) in the MSI-H gastric carcinomas compared to that in non-MSI-H gastric carcinomas (19%, P = 0.026). The cases with hTERT(+)APBs(-) were more frequent in non-MSI-H gastric carcinomas (76%) than in MSI-H gastric carcinomas (24%), and the cases with hTERT(-)APBs(+) were more frequent in MSI-H gastric carcinomas (33%) than in non-MSI-H gastric carcinomas (10%). These results suggest that alternative lengthening of telomeres-mediated telomere maintenance plays an important role for microsatellite instability-mediated stomach carcinogenesis, as well as the telomerase ribonucleoprotein complex, although the incidence of MSI-H is low. Defects of the mismatch repair system may lead to homeologous recombination of telomeric ends for the telomerase-independent telomere maintenance in gastric carcinomas.

Telomere Length, Current Perceived Stress, and Urinary Stress Hormones in Women

Telomeres are repetitive DNA sequences that cap and protect the ends of chromosomes; critically short telomeres may lead to cellular senescence or carcinogenic transformation. Previous findings suggest a link between psychosocial stress, shorter telomeres, and chronic disease risk. This cross-sectional study examined relative telomere length in relation to perceived stress and urinary stress hormones in a sample of participants (n = 647) in the National Institute of Environmental Health Sciences Sister Study, a cohort of women ages 35 to 74 years who have a sister with breast cancer. Average leukocyte telomere length was determined by quantitative PCR. Current stress was assessed using the Perceived Stress Scale and creatinine-adjusted neuroendocrine hormones in first morning urines. Linear regression models estimated differences in telomere length base pairs (bp) associated with stress measures adjusted for age, race, smoking, and obesity. Women with higher perceived stress had somewhat shorter telomeres [adjusted difference of -129bp for being at or above moderate stress levels; 95% confidence interval (CI), -292 to 33], but telomere length did not decrease monotonically with higher stress levels. Shorter telomeres were independently associated with increasing age (-27bp/year), obesity, and current smoking. Significant stress-related differences in telomere length were seen in women ages 55 years and older (-289bp; 95% CI, -519 to -59), those with recent major losses (-420bp; 95% CI, -814 to -27), and those with above-average urinary catecholamines (e.g., epinephrine: -484bp; 95% CI, -709 to -259). Although current perceived stress was only modestly associated with shorter telomeres in this broad sample of women, our findings suggest the effect of stress on telomere length may vary depending on neuroendocrine responsiveness, external stressors, and age.

Dynamics of Telomere Length and Telomerase Activity in Ph1-Negative Chronic Myeloproliferative Disorders

Evolving data demonstrate the pathogenetic significance of chromosomal ends telomeres and telomerase activity in the molecular pathogenesis of many hematological disorders. Furthermore, the presence of eroded telomeres and enhanced telomerase activity in hematopoietic cells has been associated with poor prognosis both in myeloid and lymphoid malignancies. The aim of the present study was to evaluate telomere length and telomerase activity in patients with Ph1-negative Chronic Myeloproliferative Disorders (Ph−-CMPD) either at diagnosis or during the course of the disease and to assess their possible clinical utility. Sixty-six bone marrow and 60 peripheral blood samples were obtained from 80 Ph−-CMPD patients (aged 58.57±16.42 years) and 18 healthy age-matched controls (aged 53.94±15.16 years). Thirty-six patients diagnosed suffering from Polycythemia Vera, 36 from Essential Thombocythemia, 4 from Idiopathic Myelofibrosis and 4 from Unclassified CMPD. Twenty-six samples were studied at diagnosis, whereas 54 during the course of the disease. Telomere length analysis of individual chromosome ends was performed on bone marrow metaphases using Telomere/Centromere Quantitative-Fluorescence In Situ Hybridization (T/C Q-FISH) (Dako A/S, Denmark). Telomerase activity was determined in bone marrow purified CD34(+) and CD20(+) cells as well as in peripheral blood CD3(+) T-lymphocytes and granulocytes with the PCR-based Telomeric Repeat Amplification Protocol (TRAP) assay (Roche, Germany). Gene expression of telomerase-associated proteins (hTERT, hTER, TEP1, TRF-1 and TRF-2) was assayed by Real-Time Multiplex PCR (Maximbio, USA). Ph−-CMPD patients showed significantly more eroded telomeres (P=0.010) and increased telomerase activity in CD34(+) cells (P=0.005) compared to healthy age-matched individuals. However, there was no statistical difference in telomere length (P=0.451) and enzyme activity (P=0.538) among different groups of Ph−-CMPD. Telomerase activity was not detected in the remaining hematopoietic cells both in patients and healthy controls, which was closely correlated with downregulation in hTERT mRNA expression. hTER, TEP1, TRF-1 and TRF-2 showed no apparent differential expression of mRNA in all hematopoietic cell fractions. Chromosomal aberrations (+8, +9, del13q14, del20q12) were found by FISH in 37% Ph−-CMPD patients with reduced telomere lengths (P=0.001) and enhanced telomerase activity (P=0.014), especially during the course of the disease (P=0.028). The patients with shortened telomeres displayed a higher incidence of having thrombotic or hemorrhagic events during follow-up (P=0.011), treatment failure (P=0.024) and disease progression to myelofibrosis, myelodysplastic syndromes, secondary leukemia or death (P=0.137). Nevertheless, telomerase expression was not correlated with the above complications. The event free survival (survival without complications, e.g. myelofibrosis, myelodysplastic syndromes, secondary leukemia and death) was significantly shorter in patients with reduced telomere lengths (Log Rank P=0.033), who demonstrated a 7,71-fold higher probability of having complications within five years from the initial diagnosis (95% CI=2,04–31,49 P<0.001). In conclusion, accelerated telomere shortening may not be prevented or restored by telomerase activity in most of the Ph−-CMPD myeloid cells. Loss of telomere stability seems to predispose to further genetic events such as chromosomal rearrangement and consequently to trigger off a multistage neoplastic transformation of these diseases. Moreover, the negative correlation between telomere length and survival probability of Ph−-CMPD patients is indicative that telomere dynamics may serve as a useful prognostic tool for these patients.