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Joseph DeSimone

Publications and source records attributed to Joseph DeSimone.

16 recordsLinked to original sources
PubMed2006

Imparting size, shape, and composition control of materials for nanomedicine.

This tutorial review presents an overview of strategies for the synthesis and fabrication of organic nanomaterials, specifically those with potential for use in medical applications. Examples include liposomes, micelles, polymer-drug conjugates and dendrimers. Methods of driving shape via"bottom-up" synthetic approaches and thermodynamics and kinetics are discussed. Furthermore, methods of driving shape via"top-down" physical and engineering techniques are also explored. Finally, a novel method (referred to as PRINT) used to produce nanoparticles that are shape-specific, can contain any cargo, and can be easily modified is examined along with its potential future role in nanomedicine.

Animals↗
PubMed2006

Developmental changes in DNA methylation and covalent histone modifications of chromatin associated with the epsilon-, gamma-, and beta-globin gene promoters in Papio anubis.

The baboon is a suitable and relevant animal model to study the mechanism of human globin gene switching. This investigation addresses the role of DNA methylation and histone coding in globin gene switching in the baboon, Papio anubis. Bisulfite sequencing and chromatin immunoprecipitation studies were performed in erythroid cells purified from fetuses of varying gestational ages and from adult bone marrow to analyze the manner that changes in DNA methylation of the epsilon-, gamma-, and beta-globin promoters and association of ac-H3, ac-H4, H3-dimeK4, H3-dimeK36, and H3-dimeK79 with the epsilon-, gamma-, and beta-globin promoters occur during development. Changes in DNA methylation of the epsilon- and gamma-globin gene promoters during transitional stages of globin gene switching were consistent with the stochastic model of methylation and a role of DNA methylation in gene silencing. Enrichment of ac-H3, ac-H4, and pol II at the promoters of developmentally active genes was observed, while the pattern of distribution of H3-dimeK4 and H3-dimeK79 suggests that these modifications are found near both currently and formerly active promoters. Enrichment of H3-dimeK36 at the silenced epsilon-globin gene promoter was observed. These studies demonstrate that coordinated epigenetic modifications in the chromatin structure of the beta-like globin gene promoters accompany the highly regulated changes in expression patterns of these genes during development.

Animals↗
PubMed2006

Effect of 5-aza-2'-deoxycytidine (Dacogen) on covalent histone modifications of chromatin associated with the epsilon-, gamma-, and beta-globin promoters in Papio anubis.

OBJECTIVE: Treatment with the DNA demethylating drug 5-aza-2'-deoxycytidine (Dacogen; DAC) increased fetal hemoglobin and F cells to therapeutically significant levels in patients with sickle cell disease. To gain more insight into the mechanism of action of this drug and to increase our understanding of the relationship between DNA methylation and chromatin structure, we have determined the effect of DAC on covalent histone modifications of chromatin associated with the epsilon, gamma-, and beta-globin promoters in purified bone marrow erythroid cells of four baboons (P. anubis) pre- and posttreatment. RESULTS: Fetal hemoglobin increased from 6.45%+/-1.75% in pretreatment samples to 62.1%+/-7.94% following DAC. DNA methylation of three CpG sites within the epsilon-globin promoter and 5 CpG sites within the gamma-globin promoter decreased more than 50% following DAC treatment. Levels of RNA polymerase II, acetyl-histone H3, acetyl-histone H4, dimethyl-histone H3 (lys4), dimethyl-histone H3 (lys36), and dimethyl-histone H3 (lys79) associated with the epsilon-, gamma-, and beta-globin promoters were determined by chromatin immunoprecipitation of formaldehyde-fixed chromatin followed by real-time PCR. Dacogen treatment increased the association of RNA polymerase II, acetyl-histone H3, and acetyl-histone H4 with the gamma-globin promoter but did not significantly affect the association of dimethyl-histone H3 (lys4), dimethyl-histone H3 (lys36), and dimethyl-histone H3 (lys79) with the epsilon-, gamma-, and beta-globin gene promoters. CONCLUSION: These experiments illustrate the usefulness of the baboon model to investigate the mechanism of pharmacologic reactivation of fetal hemoglobin synthesis at the molecular level.

Animals↗
PubMed2004

Modification of hematopoietic stem cell fate by 5aza 2'deoxycytidine and trichostatin A.

Efforts to change the fate of human hematopoietic stem cells (HSCs) and progenitor cells (HPCs) in vitro have met with limited success. We hypothesized that previously utilized in vitro conditions might result in silencing of genes required for the maintenance of primitive HSCs/HPCs. DNA methylation and histone deacetylation are components of an epigenetic program that regulates gene expression. Using pharmacologic agents in vitro that might possibly interfere with DNA methylation and histone deacetylation, we attempted to maintain and expand cells with phenotypic and functional characteristics of primitive HSCs/HPCs. Human marrow CD34(+) cells were exposed to a cytokine cocktail favoring differentiation in combination with 5aza 2'deoxycytidine (5azaD) and trichostatin A (TSA), resulting in a significant expansion of a subset of CD34(+) cells that possessed phenotypic properties as well as the proliferative potential characteristic of primitive HSCs/HPCs. In addition, 5azaD- and TSA-pretreated cells but not the CD34(+) cells exposed to cytokines alone retained the ability to repopulate immunodeficient mice. Our findings demonstrate that 5azaD and TSA can be used to alter the fate of primitive HSCs/HPCs during in vitro culture.

Adult↗
PubMed2004

Clinical studies with fetal hemoglobin-enhancing agents in sickle cell disease.

Fetal hemoglobin (HbF, alpha2gamma2) decreases polymerization of sickle hemoglobin, and high levels correlate with decreased morbidity and mortality in sickle cell disease (SCD). Therefore, a therapeutic goal for patients with SCD is pharmacologic reactivation of HbF. Decreased HbF production is associated with DNA methylation (by DNA methyltransferase [DNMT]) at the gamma-globin (HbF) gene promoter. The cytosine analogs 5-azacytidine and 5-aza-2'-deoxycytidine (decitabine) hypomethylate DNA by inhibiting DNMT. In early studies, 5-azacytidine produced significant HbF elevations in patients with thalassemia and SCD, but clinical development of this class of agent was halted after a poorly controlled animal study suggested that 5-azacytidine might be carcinogenic. However, the majority of preclinical studies with decitabine have suggested a chemopreventive rather than carcinogenic effect. Furthermore, decitabine, unlike 5-azacytidine, does not incorporate into RNA and is a more directed DNA-hypomethylating agent. Therefore, we have pursued studies of decitabine to pharmacologically reactivate HbF in patients with SCD. In phase I/II studies, decitabine at DNA-hypomethylating, but noncytotoxic, doses was well tolerated and effective at increasing HbF and total hemoglobin levels both in patients who had and had not responded to prior hydroxyurea therapy. In treated patients, there were marked improvements in a range of surrogate clinical endpoints measuring red blood cell adhesion, endothelial damage, and coagulation pathway activity. Pharmacologic reactivation of HbF through DNA hypomethylation holds promise as an effective disease-modifying intervention for patients with SCD. Larger studies are required to confirm the safety and effectiveness of decitabine with chronic use, and to more clearly establish its role in patients with SCD.

Anemia, Sickle Cell↗
PubMed2004

DNA hypo-methylating agents and sickle cell disease.

Fetal haemoglobin (HbF, alpha2) decreases polymerization of sickle haemoglobin (HbS) and high levels correlate with decreased morbidity and mortality in sickle cell disease (SSD). Therefore, a therapeutic goal in SSD is the pharmacologic reactivation of HbF. Silencing of the globin (HbF) gene is associated with DNA methylation. The cytosine analogues 5-azacytidine and 5-aza-2'-deoxycytidine (decitabine) hypomethylate DNA by inhibiting DNA methyl-transferase. In clinical trials, 5-azacytidine and decitabine have demonstrated the greatest efficacy in HbF reactivation. Clinical development of these drugs has been delayed by concerns regarding the carcinogenic potential of 5-azacytidine. Furthermore, controversy regarding DNA hypomethylation versus more generic cytotoxic effects as the mechanism of action suggested that other cytotoxic/cytostatic agents might be as effective. Additional preclinical data and clinical studies of decitabine have tempered many safety concerns and have confirmed that DNA hypomethylation is the mechanism of action. Pharmacologic reactivation of HbF through DNA hypomethylation holds promise as an effective disease modifying intervention for patients with SSD. Larger studies are required to confirm safety and effectiveness with chronic use.

Anemia, Sickle Cell↗
PubMed2003

Effects of 5-aza-2'-deoxycytidine on fetal hemoglobin levels, red cell adhesion, and hematopoietic differentiation in patients with sickle cell disease.

Fetal hemoglobin (HbF) decreases polymerization of sickle hemoglobin (HbS) and improves outcomes in sickle cell disease (SSD). Therefore, a therapeutic goal in SSD is pharmacologic reactivation of HbF. Silencing of the gamma-globin (HbF) gene is associated with DNA methylation. The cytosine analog 5-aza-2'-deoxycytidine (decitabine) hypomethylates DNA by inhibiting DNA methyltransferase. We examined if subcutaneous decitabine could increase HbF levels and improve SSD pathophysiology without cytotoxicity. Eight symptomatic SSD patients resistant or intolerant of standard treatment with hydroxyurea received decitabine 0.2 mg/kg subcutaneously 1 to 3 times per week in 2 cycles of 6-week duration. Treatment decreased neutrophils and increased mean HbF (6.5% to 20.4%, P <.0001) and mean total hemoglobin (76 to 96 g/L [7.6 to 9.6 g/dL], P <.001). Features of vaso-occlusive crisis pathophysiology such as red cell adhesion, endothelial damage, and coagulation pathway activity significantly improved. gamma-Globin gene promoter methylation decreased, and platelets and the proportion of megakaryocytes and erythroid cells in the marrow increased without a decrease in marrow cellularity, consistent with a DNA hypomethylating, noncytotoxic mechanism of action. Weekly subcutaneous decitabine produces cumulative increases in HbF and total hemoglobin through a noncytotoxic mechanism of action. Chronic dosing and sustained increases in hemoglobin F and total hemoglobin levels may be possible. Further studies in SSD and thalassemia are indicated.

Adult↗
PubMed2003

Preoperative white blood cell count and mortality and morbidity after coronary artery bypass grafting.

BACKGROUND: Arteriosclerosis is increasingly viewed as an inflammatory disease. The purpose of these analyses was to examine the preoperative white blood cell (WBC) count, a generalized marker of inflammation, and to assess its association with in-hospital mortality and other adverse outcomes after coronary artery bypass grafting. METHODS: Information was collected prospectively on 11,270 consecutive patients who had isolated coronary artery bypass grafting in northern New England from 1996 through 2000. Patients were divided into five categories based on their preoperative WBC count. Crude and adjusted in-hospital mortality rates and adverse event rates were calculated using logistic regression. RESULTS: Increasing WBC count across its entire range was associated with a linear increase in the mortality rate. This finding was highly significant (p [trend] < 0.001) and persisted after adjustment for patient and disease characteristics. Patients with preoperative WBC of at least 12.0 x 10(9)/L had an adjusted mortality rate 2.8 times higher than those with a WBC less than 6.0 x 10(9)/L (4.8% versus 1.7%). An increasing preoperative WBC count was also significantly associated with increasing rates of perioperative strokes and the need for an intraaortic balloon pump but was not associated with mediastinitis. CONCLUSIONS: The preoperative WBC count across its entire observed range is a statistically significant independent predictor of in-hospital death and other adverse outcomes after coronary artery bypass grafting. Although the cause of the association between increased WBC count and increased morbidity and mortality is unknown, the preoperative WBC count, which is objectively measured, inexpensive, and always available, can serve as a useful marker to help predict risk before coronary artery bypass grafting.

Aged↗
PubMed2003

Decitabine induces cell cycle arrest at the G1 phase via p21(WAF1) and the G2/M phase via the p38 MAP kinase pathway.

Methylation of the p16 (INK4a) tumor suppressor gene is observed frequently in multiple myeloma and various forms of lymphoma and mediates silencing of p16 gene expression. In this investigation, we have determined the effect of the DNA demethylating drug decitabine (DAC; 5-aza-2'-deoxycytidine) on the growth, cell cycle kinetics, RB phosphorylation, and expression of p16 (INK4a) and p21(WAF1) in EBV- human myeloma and EBV+ lymphoblastic cell lines possessing silenced, methylated p16 (INK4a) genes to: (1). evaluate its potential as a therapeutic agent and (2). investigate its mechanism of action. Demethylation of the p16 (INK4a) gene and expression of the p16 (INK4a) protein were observed using higher doses (10(-6)-10(-7)M) of drug while growth inhibition at lower doses (IC(50)=2 x 10(-8)-4 x 10(-8)M) was associated with RB dephosphorylation and increased expression of p21 (WAF1), but not with induction of p16 (INK4a), or apoptosis. Kinetic experiments demonstrated that RB dephosphorylation and the increase of p21 (WAF1) preceded the induction of p16 (INK4a). The drug induced cell cycle arrest at the G1 and G2/M phases. Antisense experiments demonstrated that the G1 arrest was mediated by transcriptional induction of p21(WAF1). In addition to these observed effects on cell cycle regulatory proteins, decitabine also increased phosphorylation of p38 MAP kinase. The G2/M arrest was inhibited by the p38 MAP kinase inhibitor SB203580, indicating that activation of p38 MAP kinase pathway was required for G2/M arrest. Thus, decitabine inhibited growth by inducing cell cycle arrest at the G1 phase mediated by p21(WAF1) and the G2/M phase through activation of the p38 MAP kinase pathway.

Antimetabolites, Antineoplastic↗
PubMed2003

Hemoglobinopathies.

The outlook for patients with sickle cell disease has improved steadily during the last two decades. In spite of these improvements, curative therapies are currently available only to a small minority of patients. The main theme of this chapter is to describe new therapeutic options that are at different stages of development that might result in further improvements in the outlook for patients with these disorders. Dr. Joseph DeSimone and his colleagues had previously made the important observation that the hypomethylating agent 5-azacytidine can reverse the switch from adult to fetal hemoglobin in adult baboons. Although similar activity was demonstrated in patients with sickle cell disease and beta-thalassemia, concern about the toxicity of 5-azacytidine prevented its widespread use in these disorders. In Section I, Dr. DeSimone discusses the role of DNA methylation in globin gene regulation and describe recent clinical experience with decitabine (an analogue of 5-azacytidine) in patients with sickle cell disease. These encouraging studies demonstrate significant fetal hemoglobin inducing activity of decitabine in patients who fail to respond to hydroxyurea. In Section II, Dr. George Atweh continues the same theme by describing recent progress in the study of butyrate, another inducer of fetal hemoglobin, in patients with sickle cell disease and beta-thalassemia. The main focus of his section is on the use of a combination of butyrate and hydroxyurea to achieve higher levels of fetal hemoglobin that might be necessary for complete amelioration of the clinical manifestations of these disorders. Dr. Atweh also describes novel laboratory studies that shed new light on the mechanisms of fetal hemoglobin induction by butyrate. In Section III, Dr. Ronald Nagel discusses the different available transgenic sickle mice as experimental models for human sickle cell disease. These experimental models have already had a significant impact on our understanding of the pathophysiology of sickle cell disease. Dr. Nagel describes more recent studies in which transgenic sickle mice provide the first proof of principle that globin gene transfer into hematopoietic stem cells inhibits in vivo sickling and ameliorates the severity of the disease. Although stroke in adult patients with sickle cell disease is not as common as in children, adult hematologists, like their pediatric colleagues, need to make management decisions in adult patients with a stroke or a history of stroke. Dr. Robert Adams has led several large clinical studies that investigated the role of transfusions in the prevention of stroke in children with sickle cell disease. Much less is known, however, about the prevention of first or subsequent strokes in adult patients with sickle cell disease. In Section IV, Dr. Adams provides some general guidelines for the management of adult patients with stroke while carefully distinguishing between recommendations that are evidence-based and those that are anecdotal in nature.

Animals↗
PubMed2002

Intensification and stimulation therapy for human immunodeficiency virus type 1 reservoirs in infected persons receiving virally suppressive highly active antiretroviral therapy.

Highly active antiretroviral therapy (HAART) has led to significant changes in mortality and morbidity in the human immunodeficiency virus type 1 (HIV-1) epidemic. Nevertheless, because of molecular mechanisms of viral persistence, HAART does not eradicate HIV-1. Didanosine and hydroxyurea were added to the antiretroviral regimens of 3 HIV-1-infected men who were receiving stable HAART and who had HIV-1 RNA levels <50 copies/mL at the initiation of the study protocol, as a novel intensification to attack cryptic viral replication; low-dose OKT3 was then administered, followed by a course of interleukin-2, to stimulate latent provirus. Replication-competent virus was undetectable after treatment, and plasma viral RNA was either undetectable or <5 copies/mL. In trial periods during which no antiretroviral therapy was administered, the patients developed plasma viral rebound. This translational approach combines novel intensification and stimulation therapy to deplete residual HIV-1 reservoirs. Additional experimental approaches must be developed if HIV-1 eradication is to become possible in patients receiving virally suppressive HAART.

Adult↗
PubMed2002

Maintenance of elevated fetal hemoglobin levels by decitabine during dose interval treatment of sickle cell anemia.

We have previously demonstrated that 5-aza-2'-deoxycytidine (decitabine) augments fetal hemoglobin (HbF) levels in patients with sickle cell anemia (SS) who did not respond to hydroxyurea (HU). The present study was designed to determine the effect of repeated decitabine dosing on HbF levels and hematologic toxicity over a 9-month treatment period. Seven patients (5 HU nonresponders) were entered. One patient had alpha-thalassemia sickle cell anemia. Decitabine was administered by intravenous infusion at a starting dose of 0.3 mg/kg per day, 5 days a week for 2 weeks, followed by a 4-week observation period. If the absolute neutrophil count dropped below 1000, the dose was reduced by 0.05 mg/kg per day in the next cycle. A drug dose was obtained for each patient, and it resulted in an elevated HbF without neutropenia (absolute neutrophil count nadir greater than 1500) or evidence of cumulative toxicity. Average HbF and average maximal HbF levels attained during the last 20 weeks of treatment for the 6 SS patients increased to 13.93% +/- 2.75% and 18.35% +/- 4.46%, respectively, from a pretreatment mean of 3.12% +/- 2.75%. Mean and mean maximal hemoglobin (Hb) levels increased from 7.23 +/- 2.35 g/dL to 8.81 +/- 0.42 g/dL and 9.73 +/- 0.53 g/dL, respectively. Individual maximal F-cell number observed during the trial was 69% +/- 10.12%. The absence of cumulative toxicity may allow shorter intervals between drug treatments, which may lead to higher hemoglobin and HbF levels after several treatment cycles and, therefore, to greater clinical improvement.

Anemia, Sickle Cell↗
PubMed2002

Long-term survival of dialysis patients after coronary bypass grafting.

BACKGROUND: Dialysis patients are undergoing coronary artery bypass grafting (CABG) with increasing frequency. The long-term effect of preoperative dialysis-dependent renal failure on mortality after CABG has not been well studied. METHODS: We conducted a prospective regional cohort study of 15,574 consecutive patients undergoing isolated CABG in northern New England from 1992 to 1997. Patient records were linked to the National Death Index to assess mortality. Five-year survival and adjusted hazard ratios were calculated. RESULTS: During 32,589 person-years of follow-up 1298 deaths were recorded. Renal failure was present in 283 patients (1.8%), and 67.8% of patients with renal failure also had diabetes or peripheral vascular disease (PVD). The annual death rate was 3.8% for nonrenal failure patients, 16.9% for all renal failure patients, 7.7% for renal failure patients without diabetes or PVD, and 23.0% for renal failure patients with diabetes or PVD. Five-year survival was 83.5% for nonrenal failure patients, 55.8% for all renal failure patients, 78.5% for renal failure patients without diabetes or PVD, and 42.2% for renal failure patients with diabetes or PVD. After adjustment for differences in base line patient and disease characteristics, renal failure patients without diabetes or PVD had a statistically nonsignificant 57% increase rate of death compared with those without renal failure; renal failure patients with diabetes or PVD had more than a fourfold increased risk of death. CONCLUSIONS: After adjustment for other risk factors, renal failure remains a highly significant predictor of decreased long-term survival in CABG patients. Patients with renal failure plus diabetes or PVD are at especially high risk of death.

Aged↗
PubMed2001

CO(2) Technology Platform: An Important Tool for Environmental Problem Solving A list of abbreviations can be found at the end of the article.

CO(2) is a good solvent for many substances when compressed into its liquid or supercritical fluid state. Above the critical temperature and critical pressure (T(c)=31 degrees C, P(c)=73.8 bar, see Figure 1 for the phase diagram for CO(2)), CO(2) has both gaslike viscosities and liquidlike densities. These moderate critical conditions allow CO(2) to be used within safe commercial and laboratory operating conditions. Small changes in temperature and pressure cause dramatic changes in the density, viscosity, and dielectric properties of CO(2), making it a tunable solvent that can be tailored for various applications. Combined, these unique properties make CO(2) a "solvent of choice" for the new millennium.

Journal Article↗