Search PubMed⌕ Search

Biomedical subjects

M Burton

Publications and source records attributed to M Burton.

At least 19 recordsLinked to original sources
PubMed2026

Carrot Juice Intake Modulates Oncogenic and Inflammatory Pathways in Advanced Colorectal Adenomas: A Pilot Feasibility Study.

Carrots are a rich dietary source of carotenoids and polyacetylenes, bioactive compounds with demonstrated anti-inflammatory and anticancer properties in experimental models. Epidemiological evidence suggests that carrot consumption is associated with a reduced risk of colorectal cancer; however, clinical data linking carrot intake to molecular changes in premalignant colorectal tissue remain limited. In this pilot intervention study, 20 patients with advanced colorectal adenomas were enrolled. Fifteen participants consumed carrot juice daily for 21 days, while five served as untreated controls. Paired adenoma biopsies were collected before and after the intervention and were analyzed using gene expression microarrays to assess transcriptional responses. Carrot juice intake was well tolerated, with adherence exceeding 95% and no reported adverse events. Transcriptomic analysis revealed modulation of key pathways implicated in colorectal carcinogenesis, including downregulation of the WNT, PI3K-AKT, and MAPK signaling pathways, as well as cyclooxygenase-2-related inflammatory pathways and cytokine signaling. These changes were consistent with reduced oncogenic signaling and attenuation of inflammatory activity within adenoma tissue. In summary, short-term carrot juice consumption was associated with coordinated suppression of molecular pathways involved in colorectal adenoma progression. These findings provide preliminary clinical evidence that a whole-food dietary intervention may influence early carcinogenic processes and support the need for larger controlled studies evaluating clinical outcomes.

Journal Article↗
PubMed2000

Improved muscle-derived expression of human coagulation factor IX from a skeletal actin/CMV hybrid enhancer/promoter.

Hemophilia B is caused by the absence of functional coagulation factor IX (F.IX) and represents an important model for treatment of genetic diseases by gene therapy. Recent studies have shown that intramuscular injection of an adeno-associated viral (AAV) vector into mice and hemophilia B dogs results in vector dose-dependent, long-term expression of biologically active F.IX at therapeutic levels. In this study, we demonstrate that levels of expression of approximately 300 ng/mL (6% of normal human F.IX levels) can be reached by intramuscular injection of mice using a 2- to 4-fold lower vector dose (1 x 10(11) vector genomes/mouse, injected into 4 intramuscular sites) than previously described. This was accomplished through the use of an improved expression cassette that uses the cytomegalovirus (CMV) immediate early enhancer/promoter in combination with a 1.2-kilobase portion of human skeletal actin promoter. These results correlated with enhanced levels of F.IX transcript and secreted F.IX protein in transduced murine C2C12 myotubes. Systemic F.IX expression from constructs containing the CMV enhancer/promoter alone was 120 to 200 ng/mL in mice injected with 1 x 10(11) vector genomes. Muscle-specific promoters performed poorly for F.IX transgene expression in vitro and in vivo. However, the incorporation of a sequence from the alpha-skeletal actin promoter containing at least 1 muscle-specific enhancer and 1 enhancer-like element further improved muscle-derived expression of F.IX from a CMV enhancer/promoter-driven expression cassette over previously published results. These findings will allow the design of a clinical protocol for therapeutic levels of F.IX expression with lower vector doses, thus enhancing efficacy and safety of the protocol. (Blood. 2000;95:2536-2542)

Actins↗
PubMed2000

Induction of replicative senescence biomarkers by sublethal oxidative stresses in normal human fibroblast.

We tested the long-term effects of sublethal oxidative stresses on replicative senescence. WI-38 human diploid fibroblasts (HDFs) at early cumulative population doublings (CPDs) were exposed to five stresses with 30 microM tert-butylhydroperoxide (t-BHP). After at least 2 d of recovery, the cells developed biomarkers of replicative senescence: loss of replicative potential, increase in senescence-associated beta-galactosidase activity, overexpression of p21(Waf-1/SDI-1/Cip1), and inability to hyperphosphorylate pRb. The level of mRNAs overexpressed in senescent WI-38 or IMR-90 HDFs increased after five stresses with 30 microM t-BHP or a single stress under 450 microM H(2)O(2). These corresponding genes include fibronectin, osteonectin, alpha1(I)-procollagen, apolipoprotein J, SM22, SS9, and GTP-alpha binding protein. The common 4977 bp mitochondrial DNA deletion was detected in WI-38 HDFs at late CPDs and at early CPDs after t-BHP stresses. In conclusion, sublethal oxidative stresses lead HDFs to a state close to replicative senescence.

Biomarkers↗
PubMed2000

Posttransplantation lymphoproliferative disorder: endoscopic findings.

BACKGROUND: Posttransplantation lymphoproliferative disorder (PTLD) may manifest a variety of nonspecific symptoms and must be suspected in the patient who undergoes solid organ transplantation. Common sites of occurrence include the gastrointestinal tract, the central nervous system, and lymphoid tissue of the oral pharynx, mediastinum, and mesentery. The large incidence of gastrointestinal involvement provides an opportunity for endoscopic diagnosis. This is the description of a characteristic endoscopic finding in patients who have undergone liver transplantation who are under evaluation for suspected PTLD. METHODS: During a 2-year period, 27 liver transplantations were performed in 24 pediatric patients. Fourteen patients underwent endoscopic evaluation. Indications for endoscopy included abdominal pain, vomiting, hematemesis, irritability, growth failure, anemia, occult blood loss, and suspected PTLD. Biopsy specimens were obtained from any endoscopically detected abnormality and from the duodenum, gastric antrum, esophagus, terminal ileum, cecum, and rectum. Specimens with suspected PTLD were evaluated with Epstein-Barr virus latent membrane stain. RESULTS: Six patients were found to have a characteristic lesion, which was raised, rubbery, and erythematous, with a central ulceration. Lesions were singular or multiple and ranged from 5 to 15 mm in diameter. Microscopic evaluation revealed a monotonous proliferation of lymphocytes. All specimens were positive for Epstein-Barr virus latent membrane protein stain. Stains for cytomegalovirus were negative. Biopsy specimens from the eight patients without identified characteristic lesions were negative for PTLD. CONCLUSIONS: Panendoscopy is a useful tool for the diagnosis and treatment of gastrointestinal PTLD. Endoscopy is easily accomplished, may provide an instantaneous result if the characteristic lesion is identified, and provides tissue for disease classification. Patients with unexplained gastrointestinal signs or symptoms should undergo panendoscopy for suspected PTLD.

Adolescent↗
PubMed2000

Human T-cell leukemia virus type 1 Tax shuttles between functionally discrete subcellular targets.

Human T-cell leukemia virus type 1 (HTLV-1) Tax is a nuclear protein with striking pleiotropic functionality. We recently demonstrated that Tax localizes to a multicomponent nuclear speckled structure (Tax speckled structure [TSS]). Here, we examine these structures further and identify a partial overlap of TSS with transcription hot spots. We used a strategy of directed expression via fusion proteins to determine if these transcription sites are the subtargets within TSS required for Tax function. When fused to human immunodeficiency virus type 1 (HIV-1) Tat, the resulting Tat-Tax fusion protein displayed neither a Tat-like nor a Tax-like pattern but rather was targeted specifically to the transcription subsites. The Tat-Tax fusion was able to activate both the HIV-1 long terminal repeat (LTR) and the HTVL-1 LTR at the same level as the individual component; thus, targeting proteins to transcription hot spots was compatible with both Tax and Tat transcription function. In contrast, the fusion with HIV-1 Rev, Rev-Tax, resulted in a pattern of expression that was largely Rev-like (nucleolar and cytoplasmic). The reduced localization of Rev-Tax to transcription sites was reflected in a 10-fold drop in activation of the HTLV-1 LTR. However, there was no loss in the ability of Tax to activate via NF-kappaB. Thus, NF-kappaB-dependent Tax function does not require targeting of Tax to these transcription sites and suggests that activation via NF-kappaB is a cytoplasmic function. Selective mutation of the nuclear localization signal site in the Rev portion resulted in retargeting of Rev-Tax to TSS and subsequent restoration of transcription function, demonstrating that inappropriate localization preceded loss of function. Mutation of the nuclear export signal site in the Rev portion had no effect on transcription, although the relative amount of Rev-Tax in the cytoplasm was reduced. Finally, in explaining how Tax can occupy multiple subcellular sites, we show that Tax shuttles from the nucleus to the cytoplasm in a heterokaryon fusion assay. Thus, pleiotropic functionality by Tax is regulatable via shuttling between discrete subcellular compartments.

Blotting, Western↗
PubMed2000

Involvement of Rb family proteins, focal adhesion proteins and protein synthesis in senescent morphogenesis induced by hydrogen peroxide.

Early passage human diploid fibroblasts develop senescent morphology prematurely within a week after a 2-hour pulse treatment with low or mild dose H(2)O(2). We test here the role of cell cycle checkpoints, cytoskeletal proteins and de novo protein synthesis in senescent morphogenesis following H(2)O(2) treatment. H(2)O(2) treatment causes transient elevation of p53 protein and prolonged inhibition of Rb hyperphosphorylation. Expression of human papillomaviral E6 gene prevented elevation of p53 but did not affect senescent morphogenesis. Expression of human papillomaviral E7 gene reduced the level of Rb protein and prevented induction of senescent morphology by H(2)O(2). The mutants of the E7 gene, in which the Rb family protein binding site was destroyed, could not reduce Rb protein or prevent H(2)O(2) from inducing senescent morphology. Senescent-like cells showed enhanced actin stress fibers. In untreated cells, vinculin and paxillin preferentially distributed along the edge of the cells. In contrast, vinculin and paxillin distributed randomly and sporadically throughout senescent-like cells. E7 expression prevented enhancement of actin filament formation and redistribution of vinculin or paxillin. Neither wild-type nor E7 cells showed changes in the protein level of actin, vinculin or paxillin measured by western blot after H(2)O(2) treatment. Finally, depletion of methionine in the culture medium after H(2)O(2) treatment prevented senescent morphogenesis without affecting dephosphorylation of Rb protein. Our results suggest that senescent morphology likely develops by a program involving activated Rb family proteins, enhancement of actin stress fibers, redistribution of focal adhesion proteins and de novo protein synthesis.

Actins↗
PubMed1999

Coexpression of factor VIII heavy and light chain adeno-associated viral vectors produces biologically active protein.

We are interested in using recombinant adeno-associated viral vectors in the treatment of hemophilia A. Because of the size constraints of recombinant adeno-associated viral vectors, we delivered the heavy and light chains of the human factor 8 (hFVIII) cDNA independently by using two separate vectors. Recombinant AAV vectors were constructed that utilized the human elongation factor 1alpha promoter, a human growth factor polyadenylation signal, and the cDNA sequences encoding either the heavy or light chain of hFVIII. Portal vein injections of each vector alone, a combination of both vectors, or a hFIX control vector were performed in C57BL/6 mice. An ELISA specific for the light chain of hFVIII demonstrated very high levels (2-10 microgram/ml) of protein expression in animals injected with the light chain vector alone or with both vectors. We utilized a chromogenic assay in combination with an antibody specific to hFVIII to determine the amount of biologically active hFVIII in mouse plasma. In animals injected with both the heavy and light chain vectors, greater than physiological levels (200-400 ng/ml) of biologically active hFVIII were produced. This suggests that coexpression of the heavy and light chains of hFVIII may be a feasible approach for treatment of hemophilia A.

Animals↗
PubMed1999

Optimization of retroviral gene transduction of mobilized primitive hematopoietic progenitors by using thrombopoietin, Flt3, and Kit ligands and RetroNectin culture.

We have investigated the ability of several cytokine combinations to improve retrovirus-mediated transduction of human primitive hematopoietic progenitors (PHPs) from mobilized peripheral blood (MPB). Retroviral infection of CD34+ cells was performed by culture on fibronectin fragment CH-296 (RetroNectin, RN), using the truncated human nerve growth factor receptor (NGFR) as the transgene reporter. Transgene expression among progeny of PHPs was assayed by FACS analysis after long-term stromal culture (LTC). Transgene delivery to PHPs was assessed by PCR of individual stromal culture-derived methylcellulose colonies (LTC-CFCs). Compared with interleukin 3 (IL-3), IL-6, and leukemia inhibitory factor (LIF), the combination of thrombopoietin (TPO), Flt3 ligand (FL), and Kit ligand (KL) effected a 73-fold increase in NGFR expression among CD34+ cells (to 14%) and a 14-fold increase in NGFR expression among total cells (to 10%) after LTC. In addition, a 2.4-fold increase in neo gene marking of LTC-CFCs was observed. A preclinical study comparing the effect of high-speed centrifugation ("spinoculation") or culture on RN during exposure to retroviral particles in teflon cell culture bags showed no difference in the efficiency of transduction of PHPs between these two methods.

Antigens, CD34↗
PubMed1999

Long-term correction of canine hemophilia B by gene transfer of blood coagulation factor IX mediated by adeno-associated viral vector.

Hemophilia B is a severe X-linked bleeding diathesis caused by the absence of functional blood coagulation factor IX, and is an excellent candidate for treatment of a genetic disease by gene therapy. Using an adeno-associated viral vector, we demonstrate sustained expression (>17 months) of factor IX in a large-animal model at levels that would have a therapeutic effect in humans (up to 70 ng/ml, adequate to achieve phenotypic correction, in an animal injected with 8.5x10(12) vector particles/kg). The five hemophilia B dogs treated showed stable, vector dose-dependent partial correction of the whole blood clotting time and, at higher doses, of the activated partial thromboplastin time. In contrast to other viral gene delivery systems, this minimally invasive procedure, consisting of a series of percutaneous intramuscular injections at a single timepoint, was not associated with local or systemic toxicity. Efficient gene transfer to muscle was shown by immunofluorescence staining and DNA analysis of biopsied tissue. Immune responses against factor IX were either absent or transient. These data provide strong support for the feasibility of the approach for therapy of human subjects.

Animals↗
PubMed1999

Public-private partnerships: working at the local level to increase the quality and number of medical homes for Medicaid children.

We have described a process in which one state's public health leaders provided a large degree of flexibility at the community level to improve pediatric health care access for children in need. This "room-to-wiggle" allowed program providers to tailor their programs to the specific needs of their communities while remaining faithful to the statewide goals. Among the most promising outcomes of the coordinated efforts to forge public-private partnerships is the continuation of the relationships that developed in the process and the further collaborations they have spawned.

Child↗
PubMed1997

Calbindin and parvalbumin are early markers of non-mitotically regenerating hair cells in the bullfrog vestibular otolith organs.

Earlier studies have demonstrated hair cell regeneration in the absence of cell proliferation, and suggested that supporting cells could phenotypically convert into hair cells following hair cell loss. Because calcium-binding proteins are involved in gene up-regulation, cell growth, and cell differentiation, we wished to determine if these proteins were up-regulated in scar formations and regenerating hair cells following gentamicin treatment. Calbindin and parvalbumin immunolabeling was examined in control or gentamicin-treated (GT) bullfrog saccular and utricular explants cultured for 3 days in amphibian culture medium or amphibian culture medium supplemented with aphidicolin, a blocker of nuclear DNA replication in eukaryotic cells. In control cultures, calbindin and parvalbumin immunolabeled the hair bundles and, less intensely, the cell bodies of mature hair cells. In GT or mitotically-blocked GT (MBGT) cultures, calbindin and parvalbumin immunolabeling was also seen in the hair bundles, cuticular plates, and cell bodies of hair cells with immature hair bundles. Thus, these antigens were useful markers for both normal and regenerating hair cells. Supporting cell immunolabeling was not seen in control cultures nor in the majority of supporting cells in GT cultures. In MBGT cultures, calbindin and parvalbumin immunolabeling was up-regulated in the cytosol of single supporting cells participating in scar formations and in supporting cells with hair cell-like characteristics. These data provide further evidence that non-mitotic hair cell regeneration in cultures can be accomplished by the conversion of supporting cells into hair cells.

Animals↗
PubMed1997

A BRCA1 founder mutation, identified with haplotype analysis, allowing genotype/phenotype determination and predictive testing.

We searched for a founder mutation in a population from one geographic region of Norway with prevalent breast/ovarian cancer families. We sampled 33 breast/ovarian cancer families and determined haplotypes of four markers linked to the BRCA1 region. Of the affected 33 index women, 13 (39.4%) shared one haplotype. In five (15% of total), an identical mutation was indicated by an abnormal truncated protein test (PTT) of exon 11 and shown to represent a 1675delA mutation. In the other index women, PTT of exon 11 showed no abnormality. No other BRCA1 founder mutation of this prevalence is likely because no other haplotype was more frequent in affecteds than in controls. All families with the 1675delA mutation in this geographic region may be considered as part of one large kindred. This allows a genotype-phenotype correlation to be precisely determined and used in genetic counselling for predictive testing within this kindred. Identification of identical haplotypes between unrelated affected individuals may be used to estimate the extent of founder effects for any mapped disease, without knowledge of the specific founder mutation.

Adult↗