Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:2.7.7.49 (reverse transcriptase)
31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Human telomerase has two core components, the RNA molecule (TERC) that provides the template for telomere repeat elongation and a reverse transcriptase (TERT) that is responsible for the addition of telomere repeats at the ends of each chromosome. Mutations in TERC have been found in the autosomal-dominant form of the inherited bone marrow failure syndrome dyskeratosis congenita and in a subset of patients with aplastic anemia and myelodysplasia. These patients have short telomeres compared to age-matched controls. These observations suggest that uncharacterised cases of dyskeratosis congenita/aplastic anemia may have mutations in TERT or other molecules that associate with TERC in the telomerase complex. We have therefore screened the TERT gene for mutation by denaturing HPLC in 80 patients with inherited and acquired bone marrow failure (24 with dyskeratosis congenita, 36 with constitutional aplastic anemia, 13 with idiopathic aplastic anemia and 7 with other forms of bone marrow failure). 15 different TERT mutations have been identified. Of these, 5 are in flanking intron sequences, 6 are synonymous and 4 are non-synonymous (missense) substitutions in the coding sequence. These are the first natural mutations of TERT to be described and we highlight their possible pathogenic role in the development of bone marrow failure.
...
PMID:Mutations in the reverse transcriptase component of telomerase (TERT) in patients with bone marrow failure. 1693 4

For the first time approved antiretroviral drugs, i.e. protease inhibitors (PI) and non-nucleoside reverse transcriptase inhibitors (NNRTI), were quantified in dried blood spots (DBS) from HIV/AIDS patient whole blood samples as the basis for therapeutic drug monitoring (TDM) by a robust simultaneous liquid chromatography/tandem mass spectrometry (LC/MS/MS) method. This study included seven PI (amprenavir, nelfinavir, indinavir, lopinavir, saquinavir, ritonavir, atazanavir) and two NNRTI (nevirapine, efavirenz). LC/MS/MS coupling was realized using a Phenomenex Synergy Max RP LC column (150 x 2 mm, 4 micro) in combination with a tandem mass spectrometer (API 2000, Applied Biosystems/MDS Sciex Concord) operating in positive and negative multiple reaction monitoring (MRM) mode with reserpine as internal standard. DBS samples were punched out and extracted with 50:50 MeOH/0.2 M ZnSO4 (v/v) as extraction reagent. The method performance data for the drugs in DBS like limits of detection (LOD, 8-70 ng/mL), lower limits of quantification (LLOQ, 41-102 ng/mL), linearity (R2, 0.9981-0.9999), linear concentration ranges (41-10.000 ng/mL), accuracies (92-113%), recoveries (62-94%), and ion suppression were investigated and are comparable to data obtained from human plasma, which is the current standard matrix for TDM of PI and NNRTI. In this case, off-line plasma sample preparation was performed by means of simple protein precipitation with 80:20 methanol/0.2 M ZnSO4 (v/v) as precipitation reagent. Significant correlations between real patient plasma and DBS were obtained for samples containing lopinavir, atazanavir, ritonavir, saquinavir, and efavirenz. DBS preparation as sampling alternative is well suited and practicable for TDM minimizing the high infection risk of HIV/AIDS samples and may facilitate sample mailing.
...
PMID:Quantification of antiretroviral drugs in dried blood spot samples by means of liquid chromatography/tandem mass spectrometry. 1619 30

To verify the expression of type 1 insulin-like growth factor receptor (IGF-IR) and its impact on hematopoietic cells apoptosis in myelodysplastic syndromes (MDS) and acute myeloid leukemias (AML), marrow samples from 16 patients with MDS and 16 patients with AML were examined along with 16 healthy donors as controls. Immunocytochemical methods (alkaline phosphatase anti-alkaline phosphatase) and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (fluorescence) were used simultaneously on nucleated cell cytospins. The ratio of IGF-IR positive cells and apoptotic cells as well as the relationship between them were then analyzed separately. A quantitative real-time reverse transcriptase-polymerase chain reaction (PCR) was administrated for six MDS cases and two normal controls to validate IGF-IR expression detected by immunochemistry. In our assay, IGF-IR appeared to have higher to lower expression rate in turn from AML (86.8+/-13.8%) to MDS (56.8+/-14.3%) and then to normal controls (40.4+/-9.6%) (P<0.01 between each group). In MDS nucleated cells, IGF-IR showed stronger expression in refractory anemia with excess blasts (RAEB)/RAEB in transformation/chronic myelomonocytic leukemia subgroup when compared to RA/RA with ringed sideroblasts cases (64.1+/-3.2 vs 53.5+/-16.2%) (P>0.05). Nucleated cells from MDS marrow underwent more apoptosis (5.4+/-3.0%) than that in normal marrow (1.2+/-0.9%) (P<0.01) and AML marrow (0.3+/-0.4%) (also, P<0.01 between each compared group). For both AML and MDS cases, apoptotic signals presented mainly in individual IGF-IR negative cells (9.0+/-4.8%) and less so in IGF-IR positive cells (1.4+/-2.4%) (P<0.01). When analyzed by groups, cell number with IGF-IR expression showed a negative correlation to apoptotic cells amount (r=-0.852; P<0.01) but positive correlation to their blast count (r=0.677; P<0.01). Outcome from real-time quantitative PCR appeared to have a trend of enhanced IGF-IR expression in advanced MDS subtypes. In conclusion, overexpression of IGF-IR existed in hematopoietic cells in MDS and AML marrows, which appeared to be contributed to disease progress.
...
PMID:Expression of type 1 insulin-like growth factor receptor in marrow nucleated cells in malignant hematological disorders: correlation with apoptosis. 1632 78

Recent data suggest that vascular endothelial growth factor (VEGF) is produced in neoplastic cells in various myeloid neoplasms and plays a key role as an autocrine regulator and mediator of angiogenesis. We examined the expression of VEGF in paraffin-embedded bone marrow sections obtained from normal donors (n = 5) and 46 patients with myelodysplastic syndromes [MDS, French-American-British (FAB)-type refractory anemia (RA), n = 10; refractory anemia with ringed sideroblasts (RARS), n = 10; refractory anemia with excess blasts (RAEB), n = 10; RAEB in transformation (RAEB-T), n = 8; chronic myelomonocytic leukemia (CMML), n = 8] by immunohistochemistry using an anti-VEGF antibody. In normal bone marrow, the anti-VEGF antibody was found to react with myeloid progenitor cells, immature monocytic cells, plasma cells and megakaryocytes, but not with erythroid cells or mature granulocytic cells. Higher levels of VEGF were found in patients with MDS, subtypes RAEB, RAEB-T and CMML, compared to patients with RA or RARS, or the normal bone marrow. These differences were found to result from expression of VEGF in immature myeloid cells in RAEB, RAEB-T and CMML. The microvessel density was also higher in patients with RAEB-T and CMML compared to RA and RARS or the normal bone marrow. Expression of VEGF mRNA was demonstrable in isolated neoplastic cells by reverse transcriptase-polymerase chain reaction in all patients examined. In aggregate, these data show that VEGF is expressed in bone marrow cells in patients with MDS. The amount of expressed VEGF is related to the percentage of immature myeloid cells (blasts and monocytic progenitors) and correlates with the FAB category.
...
PMID:Immunohistochemical detection of vascular endothelial growth factor (VEGF) in the bone marrow in patients with myelodysplastic syndromes: correlation between VEGF expression and the FAB category. 1639 58

This study was aimed to investigate the expression level of stromal cell derived factor-1 gene (SDF-1) in bone marrow mesenchymal stem cells (MSC) of patients with myelodysplastic syndrome (MDS). The MSC from bone marrow samples of MDS patients were isolated, cultured and expanded, the morphology and immunophenotype of MSC were analyzed. The expression levels of SDF-1 and internal reference GAPDH in MSC of MDS patients were detected by real-time quantitative reverse transcriptase polymerase chain reaction (RQ-RT-PCR) method and were compared with expression levels of healthy donors. The results showed that the expression levels of SDF-1 in MDS patients were significantly different from those in healthy donors (1.53 +/- 0.92 vs 5.51 +/- 0.99) (P < 0.01). SDF-1 gene expression levels in bone marrow MSC of MDS patients were significantly higher than that in MSC derived from healthy donors. It is concluded that the abnormal expression of SDF-1 gene in MSC may influence the regulation of hematopoiesis of the bone marrow microenvironment in MDS patients and it is worthy of further investigation for new clue on etiological mechanism and treatment of MDS.
...
PMID:[Expression of SDF-1 gene in bone marrow mesenchymal stem cells of patients with myelodysplastic syndrome]. 1663 97

Apoptosis has a crucial role in myelodysplastic syndromes (MDS), being responsible of the ineffective hematopoiesis characteristic of the disease. Apoptosis rate is elevated in "early phase" MDS, whereas it diminishes during disease progression to acute leukemia, consensually to the acquisition of independent growth features. Survivin is a member of the inhibitor of the apoptosis (IAP) family, with the bifunctional role of suppressing apoptosis while facilitating cell cycle progression. We investigated Survivin mRNA levels by real-time quantitative reverse transcriptase PCR analysis and Survivin protein expression by immunohistochemistry in 49 bone marrow (BM) aspirates and in 17 BM biopsies (BMB) from MDS patients. Survivin mRNA levels were higher in MDS than in control group (1.68 +/- 1.46 vs 0.25 +/- 0.22; p < 0.0001). MDS patients with low or INT1 International Scoring System for Evaluating Prognosis (IPSS) displayed higher levels of Survivin mRNA in comparison to INT2 or high IPSS (1.91 +/- 1.51 vs 0.88 +/- 0.95; p = 0.0058). Survivin protein immunoreactivity was evaluated as Survivin index S ((i)) and calculated according to the formula: S ((i)) = % of Survivin positive cells x BMB cellularity / 100. Survivin index was higher in the MDS group than in normal BM (p = 0.05). Moreover, in eight cases in which BM aspirates and trephine biopsy were available, we found a significant association between the level of Survivin mRNA and protein expression (p = 0.011). In conclusion, this study demonstrates increased levels of Survivin in MDS compared to normal controls. Moreover, higher levels of transcripts are related to "low-risk" MDS. Our results suggest an active role of Survivin in normal and in myelodysplastic hematopoiesis.
...
PMID:Survivin expression in "low-risk" and "high-risk" myelodysplastic syndromes. 1712 85

The myelodysplastic syndromes (MDS) include a diverse groups of clonal and potentially malignant bone marrow disorders. Evidences exist that microenvironment cells from MDS marrow show functional abnormalities, which may be relevant to the incidence of such a disease. Mesenchymal stem cells (MSCs) are a very important component of hematopoietic microenvironment. This study was supposed to investigate the biological characteristics and functions of MSC derived from patients with MDS in low-risk. MSCs from bone marrow samples of 11 low-risk MDS patients were isolated, cultured and expanded. Morphology, immunophenotype and osteoblasts differentiation were analyzed. Their capacity of proliferation and hematopoietic supporting in vitro were measured. A real-time quantitative reverse transcriptase polymerase chain reaction method (RQ RT-PCR) was used for detecting the expression levels of relative cytokines and chemokines in MSC. MSCs from healthy donors were used as controls. The results showed that the culture-expanded cells from MDS patients displayed a typical fibroblast-like morphology. Cells were positive for SH2 (CD105), SH3 (CD73), Thy-1 (CD90), while negative for CD34 and CD45. After induction, these cells could differentiate into osteoblasts. The proliferative ability of MSCs in MDS patients were not different from those of MSC isolated from normal bone marrow (p > 0.05), however, their capacity of hematopoietic supporting in vitro were significantly weaker (p < 0.05). RQ RT-PCR detection indicated that the SDF-1 gene expression level in MSCs of low-risk MDS patients was significantly higher than that in MSC derived from healthy donors (p < 0.01). It is concluded that the abnormal function of MSC influences the regulation of hemotopoiesis in the bone marrow microenvironment of MDS patients. It is worthy to further investigate the new clue in etiological mechanism and therapeutic strategies for MDS.
...
PMID:In vitro study of biological characteristics of mesenchymal stem cells in patients with low-risk myelodysplastic syndrome. 1871 67

Aurora kinase A, also known as aurora A, is a serine/threonine kinase that plays critical roles in mitosis entry, chromosome alignment, segregation, and cytokinesis. Overexpression of aurora A has been observed in many solid tumors and some hematopoietic neoplasms, but little is known about its expression in myeloid diseases. Because cytogenetic abnormalities play an essential role in the pathogenesis of myeloid malignancies, we hypothesized that aurora A deregulation may be involved in myelodysplastic syndromes and acute myeloid leukemia and contribute to the chromosomal instability observed in these diseases. We assessed aurora A mRNA levels in CD34(+) bone marrow blasts from nine patients with acute myeloid leukemia, 20 patients with myelodysplastic syndromes, and five normal patients serving as controls. CD34(+) blasts were isolated from bone marrow aspirate specimens using magnetic activated cell separation technology. RNA was extracted from purified CD34(+) cells, and quantitative real-time reverse transcriptase polymerase chain reaction for aurora A was performed. Immunocytochemical analyses for total aurora A, phosphorylated aurora A, Ki-67, and activated caspase 3 were performed on cytospin slides made from purified CD34(+) cells in myelodysplastic syndrome patients using standard methods. Aurora A mRNA and protein levels were correlated, as was aurora A mRNA level, with blast counts, cytogenetic abnormalities, and International Prognostic Scoring System score. We found that CD34(+) cells in myelodysplastic syndromes and acute myeloid leukemia expressed aurora A at significantly higher levels (P = 0.01 and P = 0.01, respectively) than normal CD34(+) cells. Aurora A mRNA levels correlated with total and phosphorylated protein levels (P = 0.0002 and P = 0.02, respectively). No significant correlation was found between aurora A mRNA level and blast count, blast viability, cytogenetic abnormalities, or the International Prognostic Scoring System score in patients with myelodysplastic syndromes. We conclude that aurora A is up-regulated in CD34(+) blasts from myeloid neoplasms.
...
PMID:Analysis of Aurora kinase A expression in CD34(+) blast cells isolated from patients with myelodysplastic syndromes and acute myeloid leukemia. 1966 17

Human telomeres (discovery of telomere structure and function has been recently awarded The Nobel Prize) consist of approximately 5-12 kb of tandem repeated sequences (TTAGGG)n and associated proteins capping chromosome ends which prevent degradation, loss of genetic information, end-to-end fusion, senescence and apoptosis. Due to the end-replication problem, telomere repeats are lost with each cell division, eventually leading to genetic instability and cellular senescence when telomeres become critically short. Stabilization of the telomeric DNA through telomerase activation, unique reverse transcriptase, or activation of the alternative mechanism of telomere maintenance is essential if the cells are to survive and proliferate indefinitely. Telomerase is expressed during early development and remains fully active in specific germline cells, but is undetectable in most normal somatic cells. High level of telomerase activity is detected in almost 90% of human tumours and immortalized cell lines. The hematopoietic compartment may develop genetic instability as a consequence of telomere erosion, resulting in aplastic anaemia (AA) and increased risk of myelodysplastic syndrome (MDS) and acute myeloid leukaemia (AML). Genetic instability associated with telomere dysfunction (i.e. short telomeres) is an early event in carcinogenesis. The molecular cytogenetic method telomere/centromere fluorescence in situ hybridization (T/C-FISH) can be used to characterize the telomere length of hematopoietic cells. This review describes recent advances in the molecular characterization of telomere system, the regulation of telomerase activity in cancer pathogenesis and shows that the telomeric length could be a potential clinical marker of hematologic neoplasia and prognosis of disease.
...
PMID:The role of telomeres and telomerase complex in haematological neoplasia: the length of telomeres as a marker of carcinogenesis and prognosis of disease. 2065 99

A number of cancers possess constitutive activity of the dsRNA-dependent kinase, PKR. Inhibition of PKR in these cancers leads to tumor cell death. We recently reported the increased presence of PKR phosphorylated on Thr451 (p-T451 PKR) in clinical samples from myelodysplastic syndrome (MDS) patients and acute leukemia cell lines. Whereas p-T451 PKR in low-risk patient samples or PTEN-positive acute leukemia cell lines was mostly cytoplasmic, in high-risk patient samples and acute leukemia cell lines deficient in PTEN, p-T451 PKR was mainly nuclear. As nuclear activity of PKR has not been previously characterized, we examined the status of nuclear PKR in acute leukemia cell lines. Using antibodies to N-terminus, C-terminus and the kinase domain in conjunction with a proteomics approach, we found that PKR exists in diverse molecular weight forms in the nucleus. Analysis of PKR transcripts by reverse transcriptase-PCR, and PKR-derived peptides by MS/MS revealed that these forms were the result of post-translational modifications (PTMs). Biochemical analysis demonstrated that nuclear PKR is an active kinase that can respond to stress. Given the association of PKR with PTEN and the Fanconi complex, these results indicate that PKR likely has other previously unrecognized roles in nuclear signaling that may contribute to leukemic development.
...
PMID:Multiple forms of PKR present in the nuclei of acute leukemia cells represent an active kinase that is responsive to stress. 2107 47


<< Previous 1 2 3 4 5 6 Next >>

---