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M L Bilodeau

Publications and source records attributed to M L Bilodeau.

8 recordsLinked to original sources
PubMed2001

BMP-2 stimulates tyrosinase gene expression and melanogenesis in differentiated melanocytes.

Cells of the vertebrate neural crest (crest cells) differentiate in vitro to melanocytes and sympathoadrenal (SA) progenitor cells. We have shown previously, using primary J. quail neural crest cultures, the combinatorial effect of bone morphogenetic protein-2 (BMP-2) and cAMP signaling on SA cell development. Herein, we report that in primary J. quail neural crest cultures, BMP-2 and cAMP signaling similarly exert a combinatorial effect on melanocyte development. We demonstrate that BMP-2 treatment of neural crest cells increases melanogenesis by promoting the synthesis of melanin. This increased melanin synthesis by BMP-2 is effected by the selective increase in the transcription of the tyrosinase gene, encoding the rate-limiting enzyme of the melanin biosynthetic pathway. By contrast, BMP-2 exerts no effect on the expression of the tyrosine-related proteins 1 and 2 (Tyrpl and Dct), also involved in the melanin biosynthetic process, or on the expression of microphalmia (Mitf) gene, supporting the fact that BMP-2 does not affect melanocyte differentiation. Employing transient transfection analysis of tyrosinase-reporter constructs in B16 melanoma cells, we demonstrate that the BMP-2 response-element is localized between 900 and 1,100 bp upstream from the tyrosinase transcriptional start site. These studies support a role for BMP-2 in melanogenesis by selectively targeting the expression of the tyrosinase gene involved in melanin biosynthesis.

1-Methyl-3-isobutylxanthine↗
PubMed2001

Differential expression of sympathoadrenal lineage-determining genes and phenotypic markers in cultured primary neural crest cells.

Bone morphogenetic protein-2 (BMP-2) promotes the development of primary neural crest cells grown in tissue culture to the sympathoadrenal (SA) lineage. Independent studies have characterized the expression patterns of SA-lineage genes in developing chicken embryo; however, studies using cultured primary neural crest cells have characterized only the expression patterns of the catecholaminergic markers, tyrosine hydroxylase (TH) and catecholamines (CAs). To further explore the molecular mechanisms that control SA-cell development using the in vitro model system, it is crucial to define the expression patterns of both the catecholaminergic markers and the genes regulating SA-lineage determination. Accordingly, we defined, in the absence and presence of BMP-2, the temporal expression patterns of TH and CA, the SA lineage-determining genes ASH-1, Phox2a, and Phox2b, the GATA-2 gene, and the pan-neuronal SCG10 gene. Comparison of these data with the reported temporal and spatial patterns of expression in vivo demonstrate that the inductive steps of SA-lineage determination, including the specification of neurotransmitter identity and neuronal fate, are recapitulated in the neural-crest culture system.

Adrenal Glands↗
PubMed2000

Cyclic AMP signaling functions as a bimodal switch in sympathoadrenal cell development in cultured primary neural crest cells.

Cells of the vertebrate neural crest (crest cells) are an invaluable model system to address cell fate specification. Crest cells are amenable to tissue culture, and they differentiate to a variety of neuronal and nonneuronal cell types. Earlier studies have determined that bone morphogenetic proteins (BMP-2, -4, and -7) and agents that elevate intracellular cyclic AMP (cAMP) stimulate the development of the sympathoadrenal (SA, adrenergic) lineage in neural crest cultures. To investigate whether interactive mechanisms between signaling pathways influence crest cell differentiation, we characterized the combinatorial effects of BMP-2 and cAMP-elevating agents on the development of quail trunk neural crest cells in primary culture. We report that the cAMP signaling pathway modulates both positive and negative signals influencing the development of SA cells. Specifically, we show that moderate activation of cAMP signaling promotes, in synergy with BMP-2, SA cell development and the expression of the SA lineage-determining gene Phox2a. By contrast, robust activation of cAMP signaling opposes, even in the presence of BMP-2, SA cell development and the expression of the SA lineage-determining ASH-1 and Phox2 genes. We conclude that cAMP signaling acts as a bimodal regulator of SA cell development in neural crest cultures.

1-Methyl-3-isobutylxanthine↗
PubMed1999

Differential immediate early gene expression in conditional hepatitis B virus pX-transforming versus nontransforming hepatocyte cell lines.

We report construction and characterization of tetracycline-controlled hepatitis B virus pX-expressing hepatocyte (AML12) cell lines. These cell lines were constructed in AML12 clonal isolates (clones 3 and 4), which express constitutively the tetracycline-controlled transactivator. Since pX is implicated in HCC, this immortalized hepatocyte model system was used to investigate the mechanism of pX in transformation. Clonal isolates of 3pX and 4pX lineages display conditional synthesis of pX mRNA and protein and a 2-fold increase in growth saturation density following tetracycline removal, implicating pX in monolayer overgrowth. Interestingly, only 3pX clones display pX-dependent anchorage independence. Clone 3 lineages express hepatocyte nuclear factor-1alpha and hepatocyte-specific marker genes; clone 4 lineages express hepatocyte nuclear factor-1beta and reduced levels of hepatocyte-specific marker genes, suggesting the importance of the differentiated hepatocyte in pX-mediated oncogenic transformation. Importantly, 3pX and 4pX lineages display differential expression of immediate early genes c-fos and ATF3. The pX-transforming 3pX lineage displays early, pX-dependent induction of ATF3 and prolonged induction of c-fos. The nontransforming 4pX cells display an absence of pX-dependent ATF3 induction and transient induction of c-fos. Our results support the direct link of pX expression to oncogenic transformation in 3pX lineage clones and underscore the advantage of this conditional cellular model system for studying mechanisms of pX-mediated oncogenesis.

Activating Transcription Factor 3↗
PubMed1996

Pain management knowledge, attitudes and clinical practice: the impact of nurses' characteristics and education.

This study examined the knowledge, attitudes, and clinical practice of registered nurses (N = 120) regarding pain management. Data were collected from nine varied clinical units in a large, university-affiliated, teaching hospital in an urban area of the Northeast. Demographic information was also collected to explore the relationship between nurses' characteristics, including previous pain education, clinical experience, area of clinical practice, and other variables, and knowledge, attitudes, and clinical practice. Three instruments were used in the study: (a) the Pain Management: Nurses' Knowledge and Attitude Survey; (b) a 12-item demographic questionnaire; and (c) a Pain Audit Tool (PAT) to gather data regarding pain assessment, documentation, and treatment practices from charts. Mean scores from the nursing knowledge and attitudes survey on pain revealed knowledge deficits and inconsistent responses in many areas related to pain management (mean, 62%; range, 41%-90%). The top two nurse-ranked barriers to pain management were related to patient reluctance to report pain and to take opioids for pain relief. Demographic data revealed that education about pain was most inadequate in the following areas: nonpharmacological interventions to relieve pain, the difference between acute and chronic pain, and the anatomy and physiology of pain. Chart audits with the Pain Audit Tool revealed that 76% of the charts (N = 82) lacked documentation of the use of a patient self-rating tool by nurses to assess pain, despite a high reported use (76%) of such a self-rating tool. Adjunct medications were ordered with some consistency, but appeared to be underutilized. This was especially true of nonsteroidal anti-inflammatory agents (mean use, 1%). Ninety percent of the charts had no documentation of the use of nonpharmacological interventions to relieve pain. Although this clinical setting has policies and resources in place regarding the management of pain, it would appear that they are not optimal. Practical recommendations are presented for increasing nurses' knowledge about pain management; improving the quality and the consistency of the assessment, documentation and treatment of pain; and disseminating pain management information.

Attitude of Health Personnel↗
PubMed1990

Peripheral arterial thrombolytic therapy.

The management of the patient with an acute arterial occlusion or pulmonary embolus presents many challenges. Thrombolytic therapy offers a treatment option that was not available in the past. We now have several nonsurgical options for treating patients with both peripheral arterial and pulmonary arterial occlusions. There are choices as to the appropriate drug as well as the route, dose, and length of administration. The work underway is aimed at refining technique. Studies that are ongoing now focus on which drug and mode of delivery benefits certain groups of patients. Although each clinical situation is unique, the guidelines to be established through further investigations will aid clinicians in selecting the appropriate therapeutic modality.

Arterial Occlusive Diseases↗
PubMed1989

Current management concepts for the patient with lymphedema.

The patient who is hospitalized for medical management of lymphedema presents complex issues for the nurse. Developing a care plan that will direct nursing interventions during the acute phase demands an understanding of the chronicity of the problem. The patient will require considerable teaching and support before discharge. This article provides the reader with concepts applicable to this debilitating condition.

Bandages↗