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PubMedDate not supplied

The effectiveness of anti-retroviral drug therapy for HIV-1 is associated with HIV-1 proviral DNA levels and viral selection.

The effect of combination anti-retroviral therapy regimens on HIV-1 proviral DNA levels in peripheral blood mononuclear cells was examined in 12 HIV-1-positive patients, using endpoint dilution polymerase chain reaction and serial cloning, and sequencing of the gag region of HIV-1. The major clone was defined as the most numerous of 10 analysed clones, and observation periods ranged from 8 months to 32 months (mean 19.7 +/- 10.2 months). In five patients (one with primary-stage HIV-1 infection) receiving three anti-retroviral drugs, HIV-1 RNA reduced to undetectable levels (i.e. < or = 100 copies/ml). HIV-1 proviral DNA and the number of major clones reduced in four of these patients. HIV-1 RNA levels reduced, but remained detectable, in five other patients. In the two remaining patients (both receiving two rather than three anti-retroviral drugs), HIV-1 RNA levels increased. These results suggest that the population of major clones may be affected when HIV-1 RNA levels reduce following combination regimens of anti-retroviral therapy.

Adult↗

PubMed2002

Vasoactive intestinal polypeptide/pituitary adenylate cyclase-activating peptide receptor 2 deficiency in mice results in growth retardation and increased basal metabolic rate.

Vasoactive intestinal polypeptide (VIP) and pituitary adenylate cyclase-activating peptide (PACAP) are two closely related peptides that bind two homologous G protein-coupled receptors, VIP/PACAP receptor 1 (VPAC1R) and VIP/PACAP receptor II (VPAC2R), with equally high affinity. Recent reports suggest that VPAC2R plays a role in circadian rhythm and T cell functions. To further elucidate the functional activities of VPAC2R, we generated VPAC2R-deficient mice by deleting exons VIII-X of the VPAC2R gene. The VPAC2R-deficient mice showed retarded growth and had reduced serum IGF-I levels compared with gender-matched, wild-type siblings. The mutant mice appeared healthy and fertile at a young adult age. However, older male mutant mice exhibited diffuse seminiferous tubular degeneration with hypospermia and reduced fertility rate. The mutant mice appeared to have an increase in insulin sensitivity. VPAC2R-deficient mice had increased lean mass and decreased fat mass with reduced serum leptin levels. Indirect calorimetry experiments showed that the respiratory quotient values immediately following the transition into the dark cycle were significantly higher in male knockout mice for about 4 h. Additionally, male and female VPAC2R-deficient mice presented an increased basal metabolic rate (23% and 10%, respectively) compared with their wild-type siblings. Our results suggest that VPAC2R plays an important role in growth, basal energy expenditure, and male reproductive functions.

Amino Acid Sequence↗

PubMed2006

santa and valentine pattern concentric growth of cardiac myocardium in the zebrafish.

During embryogenesis, the myocardial layer of the primitive heart tube grows outward from the endocardial-lined lumen, with new cells added to generate concentric thickness to the wall. This is a key evolutionary step, demarcating vertebrates from more primitive chordates, and is essential for normal cardiac function. Zebrafish embryos with the recessive lethal mutations santa (san) and valentine (vtn) do not thicken, but do add the proper number of cells to the myocardium. Consequently, the heart chambers are huge, constituted of a monolayered myocardium lined by endocardium. This phenotype is similar to that of the heart of glass (heg) mutation, which we described previously as a novel endocardial expressed gene. By positional cloning, we here identify san as the zebrafish homolog of human CCM1, and vtn as the homolog of human CCM2. Dominant mutations of either in humans cause vascular anomalies in the brain, known as cerebral cavernous malformations. The synergistic effects of morpholino pairs indicate that san, vtn and heg are in a genetic pathway, and san and vtn contain protein motifs, NPxY and PTB domain, respectively, known to interact. This suggests that concentric growth of the myocardium, crucial for blood pressure generation, is dictated by a heg-san-vtn signaling pathway.

Amino Acid Sequence↗

PubMedDate not supplied

Analysis of HIV-1 in the cervicovaginal secretions and blood of pregnant and nonpregnant women.

OBJECTIVES: To detect HIV-1 in cellular and acellular fractions of cervicovaginal secretions obtained by cervicovaginal lavage (CVL) and evaluate viral genotypes in the HIV-1-positive CVL samples. STUDY DESIGN/METHODS: This study consists of 37 HIV-1-seropositive pregnant and nonpregnant women from the United States. A total of 63 paired CVL and blood samples were collected. HIV-1 DNA from cervical cells (CC) and virion RNA from cervical supernatant (CS) was detected by gag polymerase chain reaction (PCR) assays. The HIV-1 genotypes were determined by analyzing the nested PCR-amplified V3 region sequences of the HIV-1 gp120 envelope gene. RESULTS: Within this cohort, 95% of the women were on single or combination antiretroviral therapy. Of the pregnant women, 63% of samples had HIV-1 viral DNA in the CC, and 29% of samples were positive for viral RNA in the CS. Among nonpregnant women, 71% of samples were positive for HIV-1 DNA in CC, and 46% of samples tested positive for virion RNA in CS. Plasma viral load ranged between 10,000 and 100,000 copies/mL and showed significant correlation with the detection of HIV-1 RNA in the CVL; this relation was less apparent with viral DNA in CC. The viral blood and CVL specimens were further analyzed by evaluating the genotypes of HIV-1 variants. In most patients, a high degree of similarity was observed between the viral sequences derived from blood and CVL samples. Two patients demonstrated closely related but somewhat distinct genotypic variants in CVL and blood. One subject showed clear compartmentalization in which distinct viral genotypes were observed in CVL and blood. Based on V3 loop analyses of gp120, with one exception, the cervicovaginal secretions harbored viral populations with a macrophage (CCR5)-tropic phenotype. CONCLUSIONS: This study demonstrates the unique characteris tics of HIV-1 strains in the genital secretions of a relatively large cohort of HIV-1-infected women in the United States. These results are important for further analysis of HIV-1 transmission and pathogenesis in vivo and for rational vaccine design.

Adult↗

PubMed1996

AAMP, a conserved protein with immunoglobulin and WD40 domains, regulates endothelial tube formation in vitro.

Angio-associated migratory cell protein (AAMP) is a newly discovered protein that is widely distributed with strong expression in endothelial cells and others with migratory potential (cytotrophoblasts, carcinoma cells, etc). AAMP is 52 kd with an isoelectric point of 5.2. Its sequence contains immunoglobulin type domains, WD40 repeats, a large acidic region with an acid box, a potential transmembrane region, potential serine/threonine phosphorylation sites, and a positively charged amino-terminal region with strong heparin binding potential (Kd = 14 pmol). Human umbilical vein endothelial cells cultured on Matrigel, a basement membrane material, form endothelial tubes (capillary-like structures). Anti-recombinant AAMP (anti-rAAMP) (1 to 10 microg/ml) inhibits this process under conditions that favor cross-linking of its ligand (AAMP). Immunofluorescent staining has shown that AAMP is distributed both intracellularly and extracellularly in cultures of endothelial cells and tubes. Molecular analysis of AAMP's protein sequence shows a striking evolutionary relationship with the YCR072c protein in Saccharomyces cerevisiae. Both the human and yeast proteins show an unusual and almost identical arrangement of immunoglobulin type domains, WD40 repeats, a protein kinase C phosphorylation consensus site in the carboxyl region, and a positively charged amino-terminal region that in AAMP has heparin binding potential. Detection of YCR072c's immunoglobulin type domains is new. Thus, AAMP is a protein that has been highly conserved in evolution and may function in the regulation of endothelial tube formation.

Adaptor Proteins, Signal Transducing↗

PubMed1995

Influence of molecular characteristics on clinical outcome in human immunodeficiency virus-associated non-Hodgkin's lymphoma: identification of a subgroup with favorable clinical outcome.

The relationship between clinical and molecular characteristics of 45 treated individuals with histologically-documented human immunodeficiency virus (HIV)-associated B-cell non-Hodgkin's lymphoma was examined to determine whether differences in molecular features of lymphoma were associated with differences in clinical outcome. Tissue specimens from these tumors were evaluated for evidence of Ig heavy-chain gene rearrangements using both Southern blot analysis and reverse transcriptase polymerase chain reaction (RT-PCR). Lymphomas were also evaluated for the presence of Epstein-Barr virus (EBV) DNA sequences and c-myc gene rearrangements. Twenty-five lymphomas were characterized as polyclonal and 20 as monoclonal. PCR amplification of expressed Ig variable (V)-region genes confirmed polyclonality in three extensively studied polyclonal lymphomas. The median CD4 count was significantly higher in the group with polyclonal disease (277/microL) than in the group with monoclonal disease (123/microL), P = .04. The complete response rate to therapy was significantly higher in patients with polyclonal disease (78%) and CD4 greater than 200/microL (81%) than in those with monoclonal disease (31%) and CD4 less than 200/microL (33%). CD4 count, clonality, and presence of EBV DNA sequences were the most important predictors of survival. Both Kaplan-Meier and Cox proportional hazards analyses showed a markedly prolonged survival in those patients with both CD4 > or = 200/microL and polyclonal disease. Histologically the polyclonal lymphomas were high grade in appearance and contained prominent macrophages. All seven surviving patients were in this group. Median survival for those individuals whose tumors contained EBV sequences was only 3.2 months (range, 0.4 to 19.5), whereas those with EBV- tumors survived for a median of 9.0 months (range, 0.7 to 65.2), P = .0007. These data indicate that molecular features of HIV-associated lymphomas may be important predictors of clinical outcome. These characteristics define a distinct subset of patients with polyclonal EBV- tumors and CD4 counts greater than 200/microL that appear to have a less aggressive clinical course.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed1995

Increased number of single-LTR HIV-1 DNA junctions correlates with HIV-1 antigen expression and CD4+ cell decline in vivo.

Human immunodeficiency type 1 (HIV-1) DNA in peripheral blood cells of HIV-1 infected individuals may be present as integrated and/or unintegrated DNA. Several reports have indicated that a major proportion of HIV-1 DNA in the asymptomatic phase is linear, full-length, and unintegrated and in the symptomatic phase either circular unintegrated or integrated in the host genome. We developed a quantitative polymerase chain reaction (PCR) technique to detect single-LTR HIV-1 DNA junctions, reflecting the presence of unintegrated single-LTR circles. In vitro infection of a CD4+ T-cell line resulted first in the increase of single-LTR junctions followed by syncytium formation and a rise of p24 antigen production. The number of single-LTR HIV-1 DNA junctions was further studied in two acutely infected individuals and in 21 long-term infected individuals. The number of single-LTR junctions was significantly correlated with CD4+ cell decline, p24 antigen expression, and total HIV-1 DNA content of peripheral blood mononuclear cells (PBMC). Single-LTR HIV-1 DNA junctions were absent from PBMC containing other forms of HIV-1 DNA in four of nine non/slow progressors relative to 2 of 12 rapid progressors/AIDS patients. We conclude from our data that quantitative detection of single-LTR HIV-1 DNA junctions can be used as an early DNA marker of the transition from clinical latency to active replication in the peripheral blood.

Base Sequence↗

PubMed2021

RP-REP Ribosomal Profiling Reports: an open-source cloud-enabled framework for reproducible ribosomal profiling data processing, analysis, and result reporting.

Ribosomal profiling is an emerging experimental technology to measure protein synthesis by sequencing short mRNA fragments undergoing translation in ribosomes. Applied on the genome wide scale, this is a powerful tool to profile global protein synthesis within cell populations of interest. Such information can be utilized for biomarker discovery and detection of treatment-responsive genes. However, analysis of ribosomal profiling data requires careful preprocessing to reduce the impact of artifacts and dedicated statistical methods for visualizing and modeling the high-dimensional discrete read count data. Here we present Ribosomal Profiling Reports (RP-REP), a new open-source cloud-enabled software that allows users to execute start-to-end gene-level ribosomal profiling and RNA-Seq analysis on a pre-configured Amazon Virtual Machine Image (AMI) hosted on AWS or on the user's own Ubuntu Linux server. The software works with FASTQ files stored locally, on AWS S3, or at the Sequence Read Archive (SRA). RP-REP automatically executes a series of customizable steps including filtering of contaminant RNA, enrichment of true ribosomal footprints, reference alignment and gene translation quantification, gene body coverage, CRAM compression, reference alignment QC, data normalization, multivariate data visualization, identification of differentially translated genes, and generation of heatmaps, co-translated gene clusters, enriched pathways, and other custom visualizations. RP-REP provides functionality to contrast RNA-SEQ and ribosomal profiling results, and calculates translational efficiency per gene. The software outputs a PDF report and publication-ready table and figure files. As a use case, we provide RP-REP results for a dengue virus study that tested cytosol and endoplasmic reticulum cellular fractions of human Huh7 cells pre-infection and at 6 h, 12 h, 24 h, and 40 h post-infection. Case study results, Ubuntu installation scripts, and the most recent RP-REP source code are accessible at GitHub. The cloud-ready AMI is available at AWS (AMI ID: RPREP RSEQREP (Ribosome Profiling and RNA-Seq Reports) v2.1 (ami-00b92f52d763145d3)).

AMI↗

PubMed2003

Deletions in env gene of HIV-1 in AIDS patients treated with highly active antiretroviral therapy (HAART).

Many AIDS patients retain high CD4+ T-cell counts despite a significant increase in PCR viral load after varied periods of treatment on drug combination with Highly Active Antiretroviral Therapy (HAART). In order to investigate this contradictory phenomenon, we assayed for infectious HIV-1 from the plasma of such patients. Since the biological assays failed to reveal any infectious virus, we undertook molecular characterization of the plasma HIV-1 genes. These studies revealed large deletions in the env gene of the free virus, while there were no deletions in the proviral DNA obtained from the infected cells of the patients' blood. This suggests that the viral particles produced and released by the infected cells during the HAART treatment have deletions in the env gene. The deletions were large enough to produce an envelop-deficient virus, which can readily explain why it is not infectious. Such a defective virus is the most likely explanation for its failure to infect the T-cells, which in turn lead to the discordance between the high PCR viral load and stable CD4+ T cell counts.

Antiretroviral Therapy, Highly Active↗

PubMed2005

HIV antiretroviral treatment: early versus later.

OBJECTIVES: Cohort studies indicate that starting highly active antiretroviral therapy (HAART) when the CD4+ T-cell count is less than 200 cells/muL is associated with poor outcomes. These studies have been unable to address how early HAART should be initiated, however. This report uses a modeling approach to compare starting HAART at a mean CD4+ T-cell count greater than 350 cells/microL (early) versus less than 350 cells/microL but greater than 200 cells/microL (later). METHODS: A Markov model tracks people with HIV infection through 6 disease stages defined by CD4+ T-cell count ranges over a 25-year period. Transition probabilities between the disease stages for 6-month periods vary according to initial viral load. Sequences of different first-line, second-line, and "salvage" antiretroviral regimens are defined, and their impact on transition probabilities is estimated. HAART effectiveness is based on data from an urban hospital-based HIV clinic, supplemented by clinical trial data. The model computes the incremental cost-effectiveness of alternative treatment patterns and includes sensitivity analyses for a range of plausible alternative input values. RESULTS: Starting HAART earlier rather than later increases total lifetime costs by $19,074, increases years of life by 1.21 years, increases discounted quality-adjusted life-years by 0.61, and has an incremental cost-effectiveness ratio of $31,266 per quality-adjusted life-year. Early therapy is more cost-effective when the impact of HAART on well-being is smaller. CONCLUSIONS: Initiation of HAART at a CD4+ T-cell count greater than 350 cells/microL may be cost-effective (less than $50,000 per quality-adjusted life-year) compared with initiating HAART at a CD4+ T-cell count less than 350 cells/microL but greater than 200 cells/muL and may result in longer quality-adjusted survival.

Antiretroviral Therapy, Highly Active↗

PubMed2001

Frequency and function of HIV-specific CD8(+) T cells.

The virus-specific CD8(+) T cell responses of 27 HIV-infected patients were studied, including a unique cohort of long term nonprogressors (LTNP) with normal CD4(+) T cell counts, low levels of plasma viral RNA, strong proliferative responses to HIV antigens and an over-representation of the HLA B*5701 class I allele. The frequencies of CD8(+) T cells specific to the majority of HIV gene products were measured by flow cytometric detection of intracellular interferon-gamma (IFN-gamma) in response to HIV-vaccinia recombinant infected autologous B cells. Very high frequencies (1.4-22%) of circulating CD8(+) T cells were found to be HIV-specific and were not only found in LTNP with reduced plasma virus. No correlation was evident between the frequency of HIV-specific CD8(+) T cells and levels of plasma viremia. In each case, the vast majority of cells (up to 17.2%) responded to Gag-Pol gene products. Although similar frequencies of Gag peptide-specific CD8(+) T cells were found in LTNP and progressors by either intracellular IFN-gamma or MHC class I tetramer staining, the breadth of these responses was greater in patients with progressive HIV infection compared with the LTNP group. The frequency of CD8(+) T cells specific for a single peptide was not representative of an individual patient's total HIV-specific CD8(+) T cell response. These data demonstrate that high numbers of HIV-specific CD8(+) T cells exist even in patients with high level viremia and progressive disease. Further, they suggest that other qualitative parameters of the CD8(+) T cell response may differentiate some patients with very low levels of plasma virus and nonprogressive infection.

Adult↗

PubMed2006

Naive T-cell depletion related to infection by X4 human immunodeficiency virus type 1 in poor immunological responders to highly active antiretroviral therapy.

The reasons for poor CD4+ T-cell recovery in some human immunodeficiency virus (HIV)-infected subjects despite effective highly active antiretroviral therapy (HAART) remain unclear. We recently reported that CXCR4-using (X4) HIV-1 could be gradually selected in cellular reservoirs during sustained HAART. Because of the differential expression of HIV-1 coreceptors CCR5 and CXCR4 on distinct T-cell subsets, the residual replication of R5 and X4 viruses could have different impacts on T-cell homeostasis during immune reconstitution on HAART. We examined this hypothesis and the mechanisms of CD4+ T-cell restoration by comparing the virological and immunological features of 15 poor and 15 good immunological responders to HAART. We found a high frequency of X4 viruses in the poor immunological responders. But the levels of intrathymic proliferation of the two groups were similar regardless of whether they were infected by R5 or X4 virus. The frequency of recent thymic emigrants in the poor immunological responders was also similar to that found in the good immunological responders, despite their reduced numbers of naïve CD4+ T cells. Our data, rather, suggest that the naïve T-cell compartment is drained by a high rate of mature naïve cell loss in the periphery due to bystander apoptosis or activation-induced differentiation. X4 viruses could play a role in the depletion of naïve T cells in poor immunological responders to HAART by triggering persistent T-cell activation and bystander apoptosis via gp120-CXCR4 interactions.

Adult↗

PubMed1994

HIV type 2 proviral load measured by quantitative polymerase chain reaction correlates with CD4+ lymphopenia in HIV type 2-infected individuals.

The efficiency of detection of 2 sets of primer pairs from putatively conserved regions of the human immunodeficiency virus type 2 (HIV-2) genome were assessed in 86 seropositive individuals from The Gambia by nested polymerase chain reaction (PCR). HIV-2 long terminal repeat (LTR) target sequences were detected in DNA extracted from peripheral blood mononuclear cells (PBMCs) in 84 of 86 (97%) individuals whereas HIV-2 integrase (pol) gene sequences were detected in 39 of 41 (95%) individuals. The use of LTR target sequences and recombinant Pfu DNA polymerase, rather than Taq polymerase, in a modified secondary amplification reaction mediated the incorporation of 35S-labeled nucleotides in a quantitative radiometric assay. This sensitive assay was used to quantify HIV-2 proviral DNA in clinical samples and compared well with estimations by limiting end-point dilution of target molecules. A linear response between counts and the number of copies amplified from serial dilutions of pROD10 plasmid DNA (3-2000 copies) yielded a standard curve to allow extrapolation to clinical data. Increased levels of HIV-2 proviral DNA, expressed as copies per 10(5) CD4-positive lymphocytes, were associated with declining CD4 count in 63 adult patients (Spearman rank correlation, r = -0.71, n = 63, p < 0.001) and with the occurrence of HIV-related clinical disease. Kruskall-Wallis analysis of variance analysis showed the mean proviral copy number (log10) to be significantly different between groups (p < 0.001) where CD4 counts were grouped as < 200/mm3 (3.4 +/- 1.05 copies), 200-500/mm3 (2.84 +/- 0.93 copies), and > 500/mm3 (1.88 +/- 0.43 copies).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed2000

Analysis of expressed immunoglobulin heavy chain genes in familial B-CLL.

In this study, we wished to determine whether familial chronic lymphocytic leukemia of B-cell phenotype (CLL) shares with sporadic B-CLL the same immunoglobulin (Ig) heavy chain variable region (VH) gene usage and occurrence of somatic mutation, to gain insight into the pathogenetic relatedness of these epidemiologically distinct forms of CLL. We therefore analyzed the expressed Ig heavy chain genes in 23 cases (11 families) of familial CLL, and compared these results with data previously reported for sporadic CLL. In addition, we assessed the relationship of the occurrence of somatic mutation to several clinical and phenotypic features. The distribution of V genes among these cases was similar to that observed in sporadic CLL: VH3 > VH1 > VH4. Thirteen of the 23 cases (57%) showed germ line VH gene sequences, whereas somatic mutations were detected in 10 cases (43%). The average mutation frequency of these latter 10 cases of was 6.7% (ranging from 1.7% to 8.8%), and evidence of antigen selection was noted in 6. Intraclonal variation, followed by clonal evolution and the appearance of a second clone over a 20-year period was observed in 1 case, suggesting that mutations can continue to accumulate after neoplastic transformation. The presence of somatic mutations correlated with age at presentation, low white blood cell (WBC) count, and low fluorescence intensity of surface CD5, and the potential significance of these relationships is discussed. Our data indicate that familial and sporadic B-CLL display a similar pattern of immunoglobulin gene usage and frequency of somatic mutation, and are consistent with a common ontogeny and immunogenetic origin for these 2 epidemiologically distinct forms of CLL. (Blood. 2000;95:1413-1419)

Adult↗

PubMed1996

Deficiency of CD34+ c-kit+ and CD34+38- hematopoietic precursors in aplastic anemia after immunosuppressive treatment.

To characterize the persistent abnormalities of hematopoiesis in aplastic anemia (AA) after immunosuppression with antilymphocyte globulin (ALG), we analyzed the quantity, phenotype, and growth properties of hematopoietic progenitor cells in 13 patients who received ALG treatment. Flow cytometry (FACS) revealed a deficiency of CD34+ cells in bone marrow (BM) of all patients. This deficiency was most severe (40-fold) in 4 patients in AA relapse. In 9 patients in remission, CD34+ cells were reduced 2-10-fold and showed no correlation with the ALG-induced improvement of peripheral blood cell counts. The proportion of CD34+ cells carrying c-kit receptors was abnormally low (2-10-fold below normal) in 5 of 13 AA patients. These patients also displayed low levels of c-kit mRNA by reverse transcription-polymerase chain reaction (RT-PCR). Furthermore, the CD34+ cell population was almost completely depleted of CD34+CD38- early hematopoietic progenitors in all AA patients. The proportion of CD34+ cells expressing lineage differentiation antigens CD33, CD71, and CD45RA in AA was increased, as compared to control BM. Formation of hematopoietic colonies by FACS-purified CD34+ cells was nearly absent in 4 relapsed patients, normal in 4 of 9, and decreased (up to 10-fold) in 5 of 9 patients in remission. The degree of impairment of colony-forming ability by AA progenitors correlated well with the reduction of CD34+ c-kit+ cells. The best proliferative response of CD34+ cells was observed in the presence of stem cell factor and, in some cases, fit3 ligand. Our results indicate that the disease process in AA depletes immature BM progenitors, thus providing a plausible explanation for persistent defects in colony-forming ability and long-term regenerative capacity of AA marrow after immunosuppression. Analysis of the immunophenotypes and the proliferative properties of purified progenitors may be useful for estimating degree of hematopoietic recovery in ALG-treated patients.

ADP-ribosyl Cyclase↗

PubMed2004

Stimulation of midgut stem cell proliferation by Manduca sexta alpha-arylphorin.

Extracts of the green-colored perivisceral fat body of newly ecdysed Manduca sexta pupae stimulate mitosis in midgut stem cells of Heliothis virescens cultured in vitro. Using a combination of cation- and anion-exchange chromatography, we have isolated a protein from these fat body extracts that accounts for the observed stem cell proliferation. SDS-PAGE analysis of the protein results in a single band of 77 kDa. Sequences of tryptic peptides from this protein are identical to internal sequences of the storage hexamer alpha-arylphorin. The alpha-arylphorin isolated by our procedure represents a small fraction of the total arylphorin present in the fat body extract. However, it alone seems responsible for the stimulation of mitotic activity in H. virescens midgut stem cells.

Amino Acid Sequence↗

PubMed2002

Characterization of hematopoietic bone marrow in male professional cyclists by magnetic resonance imaging of the lumbar spine.

PURPOSE: To prospectively evaluate hematopoietic bone marrow of male professional cyclists in relation to performance data and laboratory data, and in comparison to age-matched healthy volunteers. MATERIALS AND METHODS: Twenty male cyclists and 44 volunteers (27 males and 17 females) were prospectively studied by magnetic resonance imaging (MRI) at high-field strength. A sagittal T1-weighted (T1-w) spin-echo (SE) sequence, a gradient-echo (GE) sequence with an echo time (TE) for out-of-phase (OOP) imaging, and a turbo inversion-recovery sequence with short inversion time (TIRM) for fat suppression was used. The averaged bone marrow signal intensity (SI) of three adjacent vertebrae was related to the signal of an adjacent nondegenerative disk. RESULTS: The cyclists revealed a significantly different SI as compared to male volunteers in the OOP (0.34 +/- 0.14 vs. 0.28 +/- 0.09, P < 0.05) and T1-w sequences (1.62 +/- 0.19 vs. 1.77 +/- 0.30, P < 0.05). Only in TIRM was there a significant difference compared to female volunteers (0.36 +/- 0.08 vs. 0.44 +/- 0.04, P < 0.01). MRI data of cyclists did not correlate to hemoglobin, erythrocyte, or reticulocyte counts; ferritin, relative heart volume, relative maximal power (rPmax; W/kg bw), or relative maximal oxygen consumption (VO(2)max). A borderline linear correlation was found for hematocrit (OOP: r = 0.42, P = 0.06; TIRM: r = 0.44, P = 0.06). CONCLUSION: Bone marrow hyperplasia is observed in male professional cyclists in the axial skeleton. The MR findings are probably independent of mechanically induced marrow edema. A multifactorial cause must be considered, as single laboratory and performance data did not appear to contribute significantly to these results.

Adult↗

PubMed1996

Density-dependent inhibition of growth involves prevention of EGF receptor activation by E-cadherin-mediated cell-cell adhesion.

Normal human breast epithelial (HBE) cells grown at logarithmic phase and those at the plateau phase were starved of EGF for 3 days then stimulated with EGF. HBE cells which were growth arrested at low density responded to EGF to initiate DNA synthesis 20 h later, whereas cells growth arrested at saturated density lost their responsiveness to EGF. Although the responsiveness to EGF between the two cultures at different densities was distinct, neither the number nor the affinity of EGF receptor (EGFR) in the two cultures significantly differed. In addition, the EGFR mRNA level was not affected by an increase in the cell density. A significant difference between the two cultures was the responsiveness of EGFR to EGF. The intrinsic tyrosine kinase activity and dimerization of the EGFR in cells at low density were induced by EGF, whereas those in cells at saturated density were not. Immunostaining revealed that the EGFR was localized only in the boundary region where adjacent cells are in close contact at low density but in the entire surrounding region of each cell at saturated density. The distribution of EGFR overlapped the region where the cell-cell adhesion protein, E-cadherin, is distributed. The E-cadherin mRNA levels in the two cultures were comparable; however, nearly fivefold more E-cadherin protein accumulated in cells at saturated than at low density. Incubation of cells at saturated density with an antibody to E-cadherin followed by adding EGF resulted in the stimulation of DNA synthesis, which was preceded by autophosphorylation but not dimerization of the EGFR. The results suggested that density-dependent inhibition of growth is achieved through prevention of the EGFR activation by extensive cell-cell adhesion that is mediated by excess E-cadherin.

Antibody Specificity↗