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S J Miller

Publications and source records attributed to S J Miller.

At least 19 recordsLinked to original sources
PubMed2004

Epigenomic changes during leukemia cell differentiation: analysis of histone acetylation and cytosine methylation using CpG island microarrays.

Dysregulation of epigenetic control is an important participant in carcinogenesis. The PML/RAR alpha translocation in acute promyelocytic leukemia (APL) is an example where the resultant fusion protein recruits histone deacetylase complexes to target genes resulting in their inappropriate transcriptional repression. All-trans-retinoic acid (ATRA) acts as a ligand that relieves this repression and produces an epigenetic transcriptional reprogramming of the cancer cell. CpG island microarrays were used to analyze the DNA methylation and histone acetylation state of the human APL cell line NB4 before and after differentiation with ATRA as well as normal peripheral blood mononuclear cells (PBMC). Over 70 CpG islands within 1 kb of transcription start of a known gene are aberrantly methylated in NB4 cells compared with PBMC; however, no changes in cytosine methylation were detected following ATRA-induced differentiation. With respect to histone H4 acetylation, over 100 single-copy CpG islands within 1 kb of transcription start of a known human gene became hyperacetylated following ATRA-induced differentiation. One CpG island was aberrantly methylated in NB4 cells, but became hyperacetylated and was induced following ATRA treatment and was associated with the HoxA1 gene, suggesting it may be a target gene of ATRA in APL. In addition to single-copy sequences, a selective increase in acetylation was detected in satellite DNA when compared with other high-copy sequences, such as Alu or rDNA. In summary, ATRA stimulates complex epigenomic changes during leukemic cell differentiation, and monitoring these changes may help to identify new targets of epigenetic dysfunction.

Acetylation↗
PubMed2004

Combining isometric knee extension exercises with hip adduction or abduction does not increase quadriceps EMG activity.

OBJECTIVE: To determine if the combined isometric contractions of knee extension/hip adduction and knee extension/hip abduction will elicit a different quadriceps and gluteus medius electromyographic (EMG) pattern as compared to isometric contraction of a uniplanar knee extension exercise. METHODS: Eight healthy young adult volunteers without history of knee or quadriceps injury participated. Surface EMG data were collected from the vastus medialis oblique (VMO), vastus lateralis (VL), and gluteus medius (Gmed) muscles of the dominant leg of each subject during three single leg, weight bearing, isometric exercises (uniplanar knee extension, knee extension/hip adduction, knee extension/hip abduction). All exercises were performed at a position of 60 degrees knee flexion. Three trials lasting 5 s each were performed for each of the three exercises. EMG data from each muscle were integrated and the maximum root mean square activity over a 0.5 s window for each trial was averaged. Analyses of variance were performed with exercise (straight extension, extension/adduction, extension/abduction) as the independent variable and VMO, VL, and Gmed activity and VMO:VL ratio as dependent variables. RESULTS: A significant main effect for exercise was found for the VMO (p = 0.006) and VL (p = 0.02), but not the Gmed (p = 0.25) or the VMO:VL ratio (p = 0.13). For the VMO and VL, the uniplanar knee extension task produced significantly more EMG activity than the extension/adduction or extension/abduction tasks. CONCLUSIONS: Uniplanar knee extension exercises may be more appropriate than combining isometric knee extension exercises with hip adduction or abduction when eliciting maximal VMO and VL contractions.

Adult↗
PubMed2001

Inhibition of histone deacetylase activity causes cell type-specific induction of the PDGF-B promoter only in the absence of activation by its enhancer.

There is a strong correlation between the acetylation status of nucleosomal histones and transcriptional activity. Here we show that the histone deacetylase inhibitor trichostatin A (TSA) activates reporter gene constructs driven by the human platelet-derived growth factor B (PDGF-B) gene promoter. This activation showed an inverse correlation with the cell type-specific transcriptional activities of the promoter. The TSA response was minimal in three tumor cell lines that exhibit high-level promoter activity. In JEG-3 choriocarcinoma cells, however, where the basal promoter activity is considerably lower, there was a strong response to TSA. This was in contrast to constructs that included a PDGF-B enhancer, which were refractory to TSA effects, indicating a possible function of the enhancer in modulating acetylation status. Analysis of PDGF-B promoter mutants with respect to TSA induction revealed no specific TSA-responsive element, but suggested that association of nonacetylated histones to the PDGF-B promoter may be a default process in the absence of enhancer activation. TSA treatment of JEG-3 cells, either alone or in combination with the demethylating agent 5-azacytidine, failed to activate the silenced endogenous PDGF-B transcript, however, which appears to be repressed by additional mechanisms.

Adenocarcinoma↗
PubMed2001

Enantioselective synthesis of a mitosane core assisted by diversity-based catalyst discovery.

[reaction: see text]. Synthesis of mitosane 1 in optically pure form is reported. A retrosynthetic plan that proceeds through racemic allylic alcohol 3 was carried out. This intermediate served as a test substrate for a rapid screen of a small library (152 members) of peptide-based kinetic resolution catalysts. Peptide 9 was found to effect kinetic resolution with k(rel) = 27. Alcohol (-)-3 was then converted to optically pure (-)-1 in eight steps.

Antibiotics, Antineoplastic↗
PubMed2001

Fluorescence-based screening of asymmetric acylation catalysts through parallel enantiomer analysis. Identification of a catalyst for tertiary alcohol resolution.

A technique for high-throughput screening of kinetic resolution catalysts is reported. The method relies on carrying simultaneous kinetic resolutions in a multiwell plate format wherein each well contains a unique catalyst and a small amount of a pH-activated fluorescent sensor (3). By conducting experiments such that each catalyst is evaluated in parallel in the presence of each isolated enantiomer, an indication of catalyst activity is obtained on a per enantiomer basis. Catalysts that are highly active for one enantiomer but modestly active for another are then reevaluated in conventional kinetic resolutions. From these screens, a highly selective (k(rel) = 46) pentapeptide (4) was obtained for a model secondary alcohol (1). In addition, peptide 10 was found to afford excellent selectivities (k(rel) > 20) for a number of alcohol substrates (9a-9f) in the traditionally challenging tertiary class.

Acylation↗
PubMed2001

Selection of enantioselective acyl transfer catalysts from a pooled peptide library through a fluorescence-based activity assay: an approach to kinetic resolution of secondary alcohols of broad structural scope.

An assay employing a fluorescently labeled split and pool peptide library has been applied to the discovery of a new class of octapeptide catalysts for the kinetic resolution of secondary alcohols. A highly diverse library of peptide-based catalysts was synthesized on solid-phase synthesis beads such that each individual bead was co-functionalized with (i) a uniform loading of a pH-sensitive fluorophore and (ii) a unique peptide-based catalyst. The library was then screened for activity in acylation reactions employing (+/-)-sec-phenylethanol as the substrate and acetic anhydride as the acylation agent. From the most active catalysts, a lead peptide (4) was identified that provides a selectivity-factor (k(rel)) of 8.2 upon resynthesis and evaluation under homogeneous conditions. A "directed" second-generation split and pool peptide library was synthesized such that the new peptide sequences in the library were biased toward the lead structure. Random samples of the second generation library were screened in single bead assays that revealed several new peptide-based catalysts that afford improved selectivities in kinetic resolutions. Peptide catalyst 13 proves effective for the kinetic resolution of sec-phenylethanol (k(rel) = 20), as well as eight other secondary alcohols of a broad substrate scope (k(rel) = 4 to >50).

Acylation↗
PubMed2001

Vascular antithrombin and clinical outcome in heart transplant patients.

A procoagulant microvasculature is associated with accelerated development of coronary artery disease (CAD) and failure in heart transplant patients. This study was performed to evaluate how changes in natural anticoagulation within cardiac allografts affect outcome. We prospectively studied 141 consecutive cardiac allograft recipients who underwent transplantation between 1988 and 1997. Serial endomyocardial biopsy specimens (6.5 +/- 0.1 biopsy specimens/patient) obtained during the first 3 months after transplantation were studied immunohistochemically to evaluate vascular antithrombin, and annual coronary angiograms (3.8 +/- 0.2 angiograms/patient) were studied to evaluate CAD. Antithrombin was present in arteries and veins, but not in capillaries, of all donor heart biopsy samples. Allografts that maintained vascular antithrombin had the best prognosis. Allografts with early and persistent loss of vascular antithrombin (n = 21) developed CAD earlier (p < 0.001), developed more severe disease (p < 0.001), showed more disease progression (p < 0.001), and failed more often (p = 0.003) and earlier (p < 0.001) than allografts retaining normal vascular antithrombin (n = 45). However, allografts that lost and recovered vascular antithrombin while developing unusual capillary antithrombin binding (n = 75) had less CAD, developed CAD later, had less severe disease and less disease progression (p < 0.01), and failed less often (p = 0.01) and later (p = 0.03) than allografts with persistent loss of vascular antithrombin. The persistent lack of a thromboresistant microvasculature increases risk of subsequent CAD and graft failure. However, recovery of vascular antithrombin and development of unusual capillary antithrombin binding improves allograft outcome.

Antithrombins↗
PubMed2001

Developing indications for the use of sentinel lymph node biopsy and adjuvant high-dose interferon alfa-2b in melanoma.

OBJECTIVES: To convene a multidisciplinary panel of dermatologists, surgical oncologists, and medical oncologists to formally review available data on the sentinel lymph node (SLN) biopsy procedure and high-dose adjuvant interferon alfa-2b therapy for patients with melanoma and to rate the "appropriateness," "inappropriateness," or "uncertainty" of the procedure and therapy to guide clinical decision making in practice. PARTICIPANTS: The panel comprised 13 specialists (4 dermatologists, 4 oncologists, and 5 surgeons) from geographically diverse areas who practiced in community-based settings (n = 8) and academic institutions (n = 5). Participants were chosen based on recommendations from the relevant specialty organizations. EVIDENCE: A formal literature review was conducted by investigators at Protocare Sciences Inc, Santa Monica, Calif, on the risks and benefits of performing an SLN biopsy in patients with stage I or II melanoma and adjuvant interferon alfa-2b therapy in patients with stage II or III disease. The MEDLINE database was searched from 1966 through July 2000, and supplemental information was obtained from various cancer societies and cancer research groups. Panel participants were queried on additional sources of relevant information. Unpublished, presented data were included in abstract form on 1 recently closed clinical trial. CONSENSUS PROCESS: The RAND/UCLA Appropriateness Method was used to review and rate multiple clinical scenarios for the use of SLN biopsy and interferon alfa-2b therapy. The consensus method did not force agreement. CONCLUSIONS: The panel rated 104 clinical scenarios and concluded that the SLN biopsy procedure was appropriate for primary melanomas deeper than 1.0 mm and for tumors 1 mm or less when histologic ulceration was present and/or classified as Clark level 4 or higher. The SLN biopsy was deemed inappropriate for nonulcerated Clark level 2 or 3 melanomas 0.75 mm or less in depth and uncertain in tumors 0.76 to 1.0 mm deep unless they were ulcerated or Clark level 4 or higher. Interferon alfa-2b therapy was deemed appropriate for patients with regional nodal and/or in-transit metastasis and for node-negative patients with primary melanomas deeper than 4 mm. The panel considered the use of interferon alfa-2b therapy uncertain in patients with ulcerated intermediate primary tumors (2.01-4.0 mm in depth) and inappropriate for node-negative patients with nonulcerated tumors less than 4.0 mm deep. Specialty-specific ratings were conducted as well.

Chemotherapy, Adjuvant↗
PubMed2001

Increased vascular endothelial growth factor expression in human hearts with microvascular fibrin.

We have shown that microvascular changes that promote fibrin deposition in human cardiac allografts adversely affect clinical outcome. However, some allografts exhibit phenotypic changes in capillaries following the deposition of fibrin, which subsequently provide a significant survival advantage. The mechanism(s) involved in these capillary changes is(are) unknown. Similarly, although we have shown a significant temporal relationship between microvascular fibrin deposition and vascular endothelial growth factor (VEGF) immunoreactivity in cardiac allografts, the cellular source and relative changes in VEGF gene expression under these conditions are not known. Using immunocytochemical techniques, biopsies devoid of fibrin deposition lacked detectable VEGF immunoreactivity, whereas biopsies with fibrin deposition showed VEGF immunoreactivity in cardiocytes, interstitium, and some microvessels. By in situ hybridization, biopsies without microvascular fibrin deposition showed faint VEGF hybridization signals confined primarily to cardiocytes. In biopsies with fibrin deposition, strong VEGF hybridization signals were detected in cardiocytes, arteriolar smooth muscle cells were occasionally labeled, and endothelial cells were rarely labeled. By quantitative RT-PCR, biopsies with fibrin deposition (n=5) relatively expressed approximately three-fold more VEGF mRNA than biopsies without fibrin deposition (n=5 P=0.02). Serum VEGF titers also were greater (P=0.01) in recipients with fibrin deposition (372.9+/-66.7 pg/ml n=18) compared to recipients without fibrin deposition (172.1+/-25.0 pg/ml n=16). Collectively, these results support the hypothesis that increased myocyte-derived VEGF production following microvascular fibrin deposition in transplanted human hearts may act in a paracrine manner to promote activational and phenotypic changes in capillaries that provide a survival advantage for the allografts.

Biopsy↗
PubMed2001

Fractured Whiteside Ortholoc II knee components.

A comprehensive failure analysis was performed on 6 femoral components and 1 tibial component that fractured in service. All were Whiteside Ortholoc II total knee arthroplasty components, manufactured from cast cobalt-chromium-molybdenum alloy and porous coated. Fracture surface analysis revealed fatigue-induced failure in all cases. Most fractures occurred at regions of high stress concentration, such as sharp corners, sintered beads, and thin sections. Metallurgical examination showed significant variation in grain size, interdendritic carbides, and hardness between samples. In some cases, continuous carbide networks and voids were prominent at the bead-substrate interface. Patient weight and surgical placement were identified as contributory factors in component failure. Limitations of cast cobalt-chromium-molybdenum alloy in weight-bearing applications must be emphasized, particularly when important determinants, such as design, metallurgy, and specific clinical factors, are less than optimal.

Aged↗
PubMed2001

Samarium-153-EDTMP in the treatment of refractory rheumatoid arthritis.

We examined the preliminary safety and efficacy of intravenous samarium-153-EDTMP (Sm-153) in the treatment of refractory rheumatoid arthritis (RA). In an open-label sequential group comparison of 0.5, 1.0, and 2.0 mCi/kg, Sm-153 was administered as a single intravenous infusion to 24 patients with refractory disease. Across treatment doses, the frequency of American College of Rheumatology (ACR) 20% responses was 25%, 29%, 25%, and 33% at 2, 4, 8, and 12 weeks, respectively. Expected significant declines in absolute neutrophil count, hemoglobin, and platelet counts were observed with nadirs seen between 2-4 weeks. Sm-153, at doses of 0.5 and 1.0 mCi/kg, is well tolerated but minimally effective in the treatment of refractory RA as measured using ACR response criteria.

Adolescent↗