Acquisition of Keyboarding Skill: A Single Subject Design

The effectiveness of computer-assisted instruction,. mnemonics, and constant time delay procedures to teach basic keyboarding skills and letter/sound correspondence was investigated in this study. The study was done with an elementary-school child who has been described as having a mental disability and a speech language impairment.· He has been diagnosed with Robinow Syndrome and Attention Deficit Hyperactivity Disorder. Research has shown that computers are an effective method for teaching students with disabilities who have difficulties with paper-and-pencil tasks. Data were collected twice a week over a six-week period. The results indicated that mnemonics was ·effective in teaching letter/sound correspondence. However, no conclusions were drawn for the use of computer-assisted instruction and the constant time delay procedure in teaching basic keyboarding skills

p107 in the public eye: an Rb understudy and more

p107 and its related family members Rb and p130 are critical regulators of cellular proliferation and tumorigenesis. Due to the extent of functional overlap within the Rb family, it has been difficult to assess which functions are exclusive to individual members and which are shared. Like its family members, p107 can bind a variety of cellular proteins to affect the expression of many target genes during cell cycle progression. Unlike Rb and p130, p107 is most highly expressed during the G1 to S phase transition of the cell cycle in actively dividing cells and accumulating evidence suggests a role for p107 during DNA replication. The specific roles for p107 during differentiation and development are less clear, although emerging studies suggest that it can cooperate with other Rb family members to control differentiation in multiple cell lineages. As a tumor suppressor, p107 is not as potent as Rb, yet studies in knockout mice have revealed some tumor suppressor functions in mice, depending on the context. In this review, we identify the unique and overlapping functions of p107 during the cell cycle, differentiation, and tumorigenesis

Nitric oxide and hypoxia stimulate erythropoietin receptor via MAPK kinase in endothelial cells

Erythropoietin receptor (EPOR) expression level determines the extent of erythropoietin (EPO) response. Previously we showed that EPOR expression in endothelial cells is increased at low oxygen tension and that EPO stimulation of endothelial cells during hypoxia can increase endothelial nitric oxide (NO) synthase (eNOS) expression and activation as well as NO production. We now observe that while EPO can stimulate NO production, NO in turn can regulate EPOR expression. Human umbilical vein endothelial cells (HUVEC) treated with 10-50 pM of NO donor diethylenetriamine NONOate (DETANO) for 24 h showed significant induction of EPOR gene expression at 5% and 2% of oxygen. Also human bone marrow microvascular endothelial cell line (TrHBMEC) cultured at 21 and 2% oxygen with 50 uM DETANO demonstrated a time and oxygen dependent induction of EPOR mRNA expression after 24 and 48 h, particularly at low oxygen tension. EPOR protein was also induced by DETANO at 2% oxygen in TrHBMEC and HUVEC. The activation of signaling pathways by NO donor stimulation appeared to be distinct from EPO stimulation. In reporter gene assays, DETANO treatment of HeLa cells at 2% oxygen increased EPOR promoter activity indicated by a 48% increase in luciferase activity with a 2 kb EPOR promoter fragment and a 71% increase in activity with a minimal EPOR promoter fragment containing 0.2 kb 5'. We found that DETANO activated MAPK kinase in TrHBMEC both in normoxia and hypoxia, while MAPK kinase inhibition showed significant reduction of EPOR mRNA gene expression at low oxygen tension, suggesting MAPK involvement in NO mediated induction of EPOR Furthermore, DETANO stimulated Ala anti-apoptotic activity after 30 min in normoxia, whereas it inhibited Akt phosphorylation in hypoxia. In contrast, EPO did not significantly increase MAPK activity while EPO stimulated Akt phosphorylation in TrHBMEC in normoxia and hypoxia. These observations provide a new effect of NO on EPOR expression to enhance EPO response in endothelial cells, particularly at low oxygen tensions

Tandem E2F Binding Sites in the Promoter of the p107 Cell Cycle Regulator Control p107 Expression and Its Cellular Functions

The retinoblastoma tumor suppressor (Rb) is a potent and ubiquitously expressed cell cycle regulator, but patients with a germline Rb mutation develop a very specific tumor spectrum. This surprising observation raises the possibility that mechanisms that compensate for loss of Rb function are present or activated in many cell types. In particular, p107, a protein related to Rb, has been shown to functionally overlap for loss of Rb in several cellular contexts. To investigate the mechanisms underlying this functional redundancy between Rb and p107 in vivo, we used gene targeting in embryonic stem cells to engineer point mutations in two consensus E2F binding sites in the endogenous p107 promoter. Analysis of normal and mutant cells by gene expression and chromatin immunoprecipitation assays showed that members of the Rb and E2F families directly bound these two sites. Furthermore, we found that these two E2F sites controlled both the repression of p107 in quiescent cells and also its activation in cycling cells, as well as in Rb mutant cells. Cell cycle assays further indicated that activation of p107 transcription during S phase through the two E2F binding sites was critical for controlled cell cycle progression, uncovering a specific role for p107 to slow proliferation in mammalian cells. Direct transcriptional repression of p107 by Rb and E2F family members provides a molecular mechanism for a critical negative feedback loop during cell cycle progression and tumorigenesis. These experiments also suggest novel therapeutic strategies to increase the p107 levels in tumor cells

G1 arrest and differentiation can occur independently of Rb family function

Repression of E2F target genes is required for cell cycle arrest in Rb family (Rb, p107, and p130)-deficient cells

Functional Interactions between Retinoblastoma and c-MYC in a Mouse Model of Hepatocellular Carcinoma

Inactivation of the RB tumor suppressor and activation of the MYC family of oncogenes are frequent events in a large spectrum of human cancers. Loss of RB function and MYC activation are thought to control both overlapping and distinct cellular processes during cell cycle progression. However, how these two major cancer genes functionally interact during tumorigenesis is still unclear. Here, we sought to test whether loss of RB function would affect cancer development in a mouse model of c-MYC-induced hepatocellular carcinoma (HCC), a deadly cancer type in which RB is frequently inactivated and c-MYC often activated. We found that RB inactivation has minimal effects on the cell cycle, cell death, and differentiation features of liver tumors driven by increased levels of c-MYC. However, combined loss of RB and activation of c-MYC led to an increase in polyploidy in mature hepatocytes before the development of tumors. There was a trend for decreased survival in double mutant animals compared to mice developing c-MYC-induced tumors. Thus, loss of RB function does not provide a proliferative advantage to c-MYC-expressing HCC cells but the RB and c-MYC pathways may cooperate to control the polyploidy of mature hepatocytes

Rb inactivation and MYC activation cooperate to increase ploidy in hepatocytes.

<p><b>A.</b> Genomic PCR analysis for the deleted allele of <i>Rb</i> (<i>Rb</i>^Δ) using DNA from control, <i>MYC</i>, <i>Rb</i>, and <i>MYC/Rb</i> mutant livers before the development of tumors in <i>Rosa26^+/CreER</i> mice. <i>Actin</i> serves as a positive PCR control. <b>B.</b> Quantification of immunostaining experiments for the number of Ki67⁺ liver cells per field on control, <i>MYC</i>, <i>Rb</i>, and <i>MYC/Rb</i> mutant liver sections 5 weeks after the deletion of <i>Rb</i> and the induction of <i>MYC</i>. The number of positive cells in eight 20× fields was counted in 2 mice for each treatment group. The differences observed are not significant in a t-test. <b>C.</b> Representative microphotographs of hepatocytes from a mouse injected with corn oil alone in the presence of doxycycline (wild-type for RB and MYC) and a mouse injected with tamoxifen in the absence of doxycycline are shown (<i>MYC/Rb</i> mutant liver). Arrows show a small nucleus in the control mouse and a large nucleus in the mutant mouse. <b>D.</b> Quantification of ploidy by FACS of hepatocyte populations from control (n = 5), <i>MYC</i> (n = 8), <i>Rb</i> (n = 5), and <i>MYC/Rb</i> (n = 8) mutant livers 5 months after <i>Rb</i> deletion (<i>Rosa26^+/CreER</i> mice) and MYC activation. Only statistically significant differences are shown.</p

Rb inactivation does not affect the degree of proliferation or cell death of MYC-induced HCC.

<p><b>A–C.</b> Immunofluorescence staining for Ki67 (<b>A</b>), BrdU (<b>B</b>), and cleaved caspase 3 (CC3) (<b>C</b>) on <i>MYC</i> mutant non-tumor liver tissue and tumor tissue from <i>MYC</i> and <i>MYC/Rb</i> mutant mice. DAPI nuclear staining is used to indicate the density of cells on the sections. The pictures shown are representative of each group. <b>D.</b> Quantification of staining shown in A. The number of positively stained cells for each antibody over the number of DAPI stained cells expressed as a percent was determined using the BioQuant software. For each antibody and genotype combination the average of n = 2 mice was calculated where each n is the average percent of positive cells from three fields containing at least 250 cells each.</p