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Biomedical subjects

J DeSimone

Publications and source records attributed to J DeSimone.

At least 19 recordsLinked to original sources
PubMed1999

Residual HIV-1 RNA in blood plasma of patients taking suppressive highly active antiretroviral therapy.

CONTEXT: Despite suppressive treatment with highly active antiretroviral therapy (HAART), replication-competent virus can still be isolated from peripheral blood mononuclear cells and genital cells of many individuals receiving suppressive HAART. OBJECTIVE: To determine whether free virion RNA can be detected in the blood plasma and/or genital tract fluids from patients receiving suppressive HAART. DESIGN: Prospective cohort study conducted from November 1998 to May 1999. SETTING: Academic medical center. PATIENTS: Human immunodeficiency virus 1-infected individuals (20 men and 2 women) shown in our laboratories to have fewer than 50 copies/mL of HIV-1 RNA in peripheral blood plasma while taking suppressive HAART. MAIN OUTCOME MEASURES: Free virion RNA levels in peripheral blood plasma and genital fluids, quantified using an ultrasensitive reverse transcriptase polymerase chain reaction able to quantify cell-free virion RNA to a lower limit of 5 copies/mL and qualitatively detect viral RNA below this level. RESULTS: In all 22 patients, residual viral RNA could be detected in the peripheral blood plasma (mean level, 17 copies/mL). The presence of viral RNA suggests that ongoing viral replication is occurring, albeit at low levels, in each patient evaluated. Viral RNA levels were lower in most patients' genital fluids compared with blood plasma and in 12 patients were undetectable. CONCLUSIONS: These data suggest that low-level replication of HIV-1 in patients taking suppressive HAART may be demonstrated not only in peripheral blood mononuclear cells but also in peripheral plasma as cell-free virion RNA. Complete ablation of viral replication may require intensification of antiretroviral therapies beyond standard suppressive HAART.

Anti-HIV Agents↗
PubMed1999

Growth inhibition of a human myeloma cell line by all-trans retinoic acid is not mediated through downregulation of interleukin-6 receptors but through upregulation of p21(WAF1).

All-trans retinoic acid (ATRA) has previously been shown to inhibit the growth of OPM-2 human myeloma cells. The growth inhibition was postulated to result from a transcriptional downregulation of interleukin-6 receptor alpha (IL-6Ralpha) with IL-6Rbeta (gp130) unaffected. To formally test this hypothesis, an expression vector designed for constitutive IL-6Ralpha expression was constructed and used for transfection of OPM-2 cells. Six stable transfectants were cloned. The expression of IL-6Ralpha was shown by immunofluorescence with anti-IL-6Ralpha antibody and 125I-IL-6 binding. In five of six transfectant clones, cellular IL-6Ralpha was 1.5- to 6-fold higher than the parental cells, with the ligand binding affinity unchanged. While ATRA reduced IL-6Ralpha expression in the parental OPM-2 cells, it enhanced its expression in these five transfectants. The clonogenic growth of these transfectants, however, remained strongly inhibited by ATRA. Further analysis, comparing the parental OPM-2 cells and a representative transfectant, clone C5, showed that IL-6 caused rapid tyrosine phosphorylation of gp130 in both OPM-2 and C5 clones. Pretreatment with ATRA greatly reduced IL-6-induced gp130 phosphorylation in OPM-2 cells, reflecting a reduction in cellular IL-6Ralpha. In contrast, IL-6-induced gp130 phosphorylation was not reduced by ATRA pretreatment in C5 cells, indicating that the expressed IL-6Ralpha was functional. Similar to OPM-2 cells, C5 cells were sensitive to growth inhibition by dexamethasone, which was entirely reversed by exogenous IL-6, suggesting that the IL-6 postreceptor signal transduction remained intact. ATRA was further shown to upregulate p21(WAF1) expression and cause dephosphorylation of the retinoblastoma protein (pRB) in both OPM-2 and C5 cells. Exogenous IL-6 also failed to reverse these effects of ATRA. Thus, the growth inhibitory activity of ATRA is not mediated through cellular IL-6Ralpha downregulation and is likely to result from a direct upregulation of p21(WAF1) and consequent dephosphorylation of pRB.

Antineoplastic Agents↗
PubMed1999

Self-reported allergic reactions to peanut on commercial airliners.

BACKGROUND: Allergic reactions to food occurring on commercial airlines have not been systematically characterized. OBJECTIVE: We sought to describe the clinical characteristics of allergic reactions to peanuts on airplanes. METHODS: Participants in the National Registry of Peanut and Tree Nut Allergy who indicated an allergic reaction while on a commercial airliner were interviewed by telephone. RESULTS: Sixty-two of 3704 National Registry of Peanut and Tree Nut Allergy participants indicated a reaction on an airplane; 42 of 48 patients or parental surrogates contacted confirmed the reaction began on the airplane (median age of affected subject, 2 years; range, 6 months to 50 years). Of these, 35 reacted to peanuts (4 were uncertain of exposure) and 7 to tree nuts, although 3 of these 7 reacted to substances that may have also contained peanut. Exposures occurred by ingestion (20 subjects), skin contact (8 subjects), and inhalation (14 subjects). Reactions generally occurred within 10 minutes of exposure (32 of 42 subjects), and reaction severity correlated with exposure route (ingestion > inhalation > skin). The causal food was generally served by the airline (37 of 42 subjects). Medications were given in flight to 19 patients (epinephrine to 5) and to an additional 14 at landing/gate return (including epinephrine to 1 and intravenous medication to 2), totaling 79% treated. Flight crews were notified in 33% of reactions. During inhalation reactions as a result of peanut allergy, greater than 25 passengers were estimated to be eating peanuts at the time of the reaction. Initial symptoms generally involved the upper airway, with progression to the skin or further lower respiratory reactions (no gastrointestinal symptoms). CONCLUSIONS: Allergic reactions to peanuts and tree nuts caused by accidental ingestion, skin contact, or inhalation occur during commercial flights, but airline personnel are usually not notified. Reactions can be severe, requiring medications, including epinephrine.

Aerospace Medicine↗
PubMed1999

Lumbar vertebral osteomyelitis with mycotic abdominal aortic aneurysm caused by highly penicillin-resistant Streptococcus pneumoniae.

We present a case of vertebral osteomyelitis with an adjacent abdominal aortic mycotic aneurysm caused by a highly penicillin-resistant Streptococcus pneumoniae strain. The occurrence of all three phenomena in a single patient has not been previously described. This presentation offers the opportunity to reflect on the increasing incidence of S. pneumoniae as a resistant pathogen, the treatment of highly penicillin-resistant S. pneumoniae, and the etiologic agents of both vertebral osteomyelitis and mycotic aneurysm.

Aneurysm, Infected↗
PubMed1996

Laparoscopic knot security.

The security of several types of laparoscopic and open knots and varying suture materials was tested in an attempt to improve suture and knot selection for advanced laparoscopic procedures. Six different types of knots and five suture materials were tested. All sutures were of 2-0 size, and laparoscopic knots were tied using a pelvic trainer. A typical number of square throws was used for each suture. Stress was gradually applied by withdrawing the ends of a manual digital tensiometer until either the knot slipped or the suture parted. The maximum stress withstood by the knot-suture complex was recorded, as was whether the knot was secure (i.e., whether the knot held until the suture broke). The data were analyzed using analysis of variance to compare the knot security of the various knot types and the different sutures using a given knot. No significant difference was found in security or stress resistance between laparoscopic square and open square knots or in the Dacron, polypropylene, and expand polytetrafluoroethylene (ePTFE) extracorporeal and intracorporeal knots, with the exception of ePTFE intracorporeal knots, which were significantly less secure (p = 0.028). Silk suture was significantly less secure than all the other sutures tested for all knots tested (p < 0.0001). The Roeder's and Fisherman's knots were the least secure of all laparoscopic knots in all sutures tested (p < 0.0001), with the exception of polyglactin tied with a fisherman's knot, which was as secure as the extracorporeal and intracorporeal polyglactin knots. These experiments showed laparoscopic square knots to be as secure as open square knots; removing the operating finger from the knot does not seem to affect the security of a well-tied square knot. Furthermore, of the permanent sutures tested, there was no substantive difference in the security of laparoscopic intracorporeally and extracorporeally tied knots, except that ePTFE was more secure when tied with extracorporeal throws. Our data also suggest that silk is not as secure as other permanent suture materials.

Humans↗
PubMed1994

The 87-kD A gamma-globin enhancer-binding protein is a product of the HOXB2(HOX2H) locus.

Developmental regulation of globin gene expression may be controlled by developmental stage-specific nuclear proteins that influence interactions between the locus control region and local regulatory sequences near individual globin genes. We previously isolated an 87-kD nuclear protein from K562 cells that bound to DNA sequences in the beta-globin locus control region, gamma-globin promoter, and A gamma-globin enhancer. The presence of this protein in fetal globin-expressing cells and its absence in adult globin-expressing cells suggested that it may be a developmental stage-specific factor. A lambda gt11 K562 cDNA clone encoding a portion of the HOXB2 (formerly HOX2H) homeobox gene was isolated on the basis of the ability of its beta-galactosidase fusion protein to bind to the same DNA sequences as the 87-kD K562 protein. Because no other relationship had been established between the 87-kD K562 protein and the HOXB2 protein other than their ability to bind ot the same DNA sequences, we have investigated whether the two proteins are related antigenically. Our data show that antisera produced against the HOXB2-beta-gal fusion protein and a synthetic HOXB2 decapeptide react specifically with an 87-kD protein from K562 nuclear extract, showing that the 87-kD K562 nuclear protein is a product of the HOXB2 locus, and is the first demonstration of cellular HOXB2 protein.

DNA-Binding Proteins↗
PubMed1994

Increased binding of Sp1 to the gamma-globin gene promoter upon site-specific cytosine methylation.

We have studied the effect of site-specific cytosine methylation on the binding of nuclear proteins to the gamma-globin promoter region from -71 to -34. This sequence was recently shown to contain a stage selector element responsible for increased transcription from the gamma compared to the beta promoter when both are linked to Locus Control Region enhancer sequences. We observed that Sp1 binding to this sequence is increased upon site-specific cytosine methylation, such that only methylation of the cytosine in the -50 CpG dinucleotide effects Sp1 binding. Methylation of the distal C of the Hpall site has no effect. The possible functional role of Sp1 as a repressor of gamma-globin synthesis is discussed.

Animals↗
PubMed1993

Fetal hemoglobin reactivation in baboon and man: a short perspective.

Present concepts of the mechanism of reactivation of synthesis of fetal hemoglobin (HbF) in the adult under conditions of erythropoietic stress are briefly reviewed. Since HbF can be considered an effective natural antisickling agent, the reactivation of its synthesis in patients with sickle cell anemia as a desirable therapeutic goal has been extensively explored since the discovery in 1982 that 5-azacytidine increases HbF levels in the baboon. Hydroxyurea (HU) has become the most widely used agent, although its effectiveness in increasing HbF levels and the number of F cells is highly variable. Recent investigations are cited showing that other agents such as butyrate, and the addition of recombinant hemopoietic growth factors, such as erythropoietin and stem cell factor, especially in combination with HU, offer important therapeutic possibilities. Transacting nuclear proteins are briefly discussed as possibly having a future role in the efforts of stimulating gamma-chain synthesis.

Anemia, Sickle Cell↗
PubMed1991

A homeodomain protein binds to gamma-globin gene regulatory sequences.

Developmental regulation of gamma-globin gene expression probably occurs through developmental-stage-specific trans-acting factors able to promote the interaction of enhancer elements located in the far upstream locus control region with regulatory elements in the gamma gene promoters and 3' A gamma enhancer located in close proximity to the genes. We have detected a nuclear protein in K562 and baboon fetal bone marrow nuclear extracts capable of binding to A+T-rich sequences in the locus control region, gamma gene promoter, and 3' A gamma enhancer. SDS/polyacrylamide gel analysis of the purified K562 binding activity revealed a single protein of 87 kDa. A K562 cDNA clone was isolated encoding a beta-galactosidase fusion protein with a DNA binding specificity identical to that of the K562/fetal bone marrow nuclear protein. The cDNA clone encodes a homeodomain homologous to the Drosophila antennapedia protein.

Animals↗
PubMed1989

Differences in burst morphology among baboon species.

Baboon species differ markedly in the proportions of fetal hemoglobin (HbF) they produce in response to hemopoietic stress. Bone marrow erythroid progenitor cells from untreated and stressed baboons of three species were cultured to determine if differences in number, size, or other characteristics of the colonies and bursts could be correlated with the HbF response. BFU-E from adult Papio cynocephalus produced high proportions of macroscopic, well-hemo-globinized bursts, whereas those from P. anubis and P. papio produced only small, moderately hemoglobinized bursts. The species-specific differences in burst characteristics did not correlate with the in vivo HbF response to stress and they were not altered by variations in culture conditions. However, bone marrow BFU-E from P. anubis and P. cynocephalus fetuses produced similar bursts, suggesting developmental regulation of progenitor cell growth patterns. The proportions of macroscopic bursts were reduced in P. cynocephalus animals undergoing hemopoietic stress, suggesting that culture is a more severe erythropoietic stress for P. anubis and P. papio BFU-E than for P. cynocephalus BFU-E.

Animals↗
PubMed1986

Effect of lead and ethanol upon gamma-globin synthesis in sickle reticulocytes.

There is evidence from both in vivo and in vitro studies that the synthesis of hemoglobin can be modified by posttranslational alterations in the assembly of the tetrameric molecule. Globin biosynthesis in reticulocytes of patients with sickle cell disease was studied to ascertain the effects of lead and ethanol on gamma-globin chain synthesis and hemoglobin assembly. In incubations containing lead (400 micrograms/dl) or ethanol (1.0 M) there were 86.7 +/- 139.7% and 542.7 +/- 397.0% increases in the relative synthesis of the gamma-globin chain. This was associated with a relative reduction in alpha-chain synthesis, as estimated by changes in the alpha/gamma + beta S synthesis ratio, as well as a marked reduction in total globin synthesis.

Anemia, Sickle Cell↗
PubMed1986

On the mechanism of Hb F elevations in the baboon by erythropoietic stress and pharmacologic manipulation.

Maximal fetal hemoglobin (Hb F) elevations in the baboon subsequent to phenyl hydrazine-induced hemolytic anemia, bleeding, bleeding plus hydroxyurea (HU), or cytosine arabinoside were two to three times lower than those achieved with bleeding plus 5-azacytidine (azaC). Because, in the baboon, maximal elevations in F cell numbers occurred with bleeding alone, changes in the levels of Hb F in hemolysates and in Hb F per F cell could be considered to be due to the administered drugs. Erythropoietic toxicity of azaC was minimal, making it unlikely that the marked elevations of Hb F were due to shifts in the population of erythroid progenitors and precursors and more likely that they were related to a biochemical effect of the drug on DNA. The data indicate marked DNA hypomethylation. This was also found to be associated, but to a much lesser extent, with the modest Hb F elevations after bleeding, hemolysis, and treatment with HU. This drug had greater erythroid toxicity than azaC, and it appeared that the Hb F elevations occurred mainly on the rebound from the early cytotoxicity. The explanation of the molecular DNA changes with this drug and in erythropoietic stress alone remains unknown.

Anemia, Hemolytic↗
PubMed1985

Tetrahydrouridine, cytidine analogues, and hemoglobin F.

5-Azacytidine (azaC) has previously been shown to raise Hb F levels in the repeatedly phlebotomized baboon (PCV: around 20%). The administration of tetrahydrouridine (THU), an inhibitor of the enzymatic conversion of azaC to 5-azauridine, made it possible to reduce the amount of azaC and also of 2-deoxy-5-azacytidine (d-azaC) by more than 90% and still achieve maximal Hb F elevations. However, the granulocytopenia, usually occurring after 5-azaC, was not altered by the lowering of the dosages in the presence of THU. Thus, the granulocytopenia is not due to 5-azauridine or other catabolic products resulting from deamination. It is also unlikely that it is caused by a direct influence of azaC on RNA since d-azaC also causes granulocytopenia. The persistence of reticulocytosis throughout the treatment with azaC or d-azaC makes it appear likely that the observed increase in Hb F levels to more than 60% of total hemoglobin is not due to a cytotoxic effect on erythropoiesis resulting in a shift of cell populations toward greater immaturity, but to a direct influence of the drug on the regulation of gamma globin chain production.

Agranulocytosis↗
PubMed1984

5-Azacytidine and fetal hemoglobin.

The evidence that 5-azacytidine stimulates the production of Hb F and F cells in baboon and man is reviewed. The mechanism of this effect is not entirely clear, but 5-azacytidine produces hypomethylation of the gamma gene at certain sites, and gene expression and DNA hypomethylation are related phenomena in many other systems. Other mechanisms have been postulated by other investigators. The therapeutic significance of increased Hb F levels in homozygous beta thalassemia and sickle cell anemia is exemplified. The potential risk of carcinogenicity has delayed more extensive clinical trials.

Adult↗
PubMed1984

Speciation in the baboon and its relation to gamma-chain heterogeneity and to the response to induction of HbF by 5-azacytidine.

In the baboon (Papio species), the two nonallelic gamma-genes produce gamma-chains that differ at a minimum at residue 75, where isoleucine (I gamma-chain) or valine (V gamma) may be present. This situation obtains in baboons that are sometimes designated as Papio anubis, Papio hamadryas, and Papio papio. However, in Papio cynocephalus, although the I gamma-chains are identical with those in the above mentioned types, the V gamma-chains have the substitutions ala----gly at residue 9 and ala----val at residue 23. The V gamma-chains of P. cynocephalus are called V gamma C to distinguish them from the V gamma A-chains of P. anubis, etc. A single cynocephalus animal has been found to have only normal I gamma-chains and I gamma C-chains (that is, glycine in residue 9, valine in 23, and isoleucine in 75). When HbF is produced in response to stress with 5-azacytidine, P. anubis baboons respond with greater production than do P. cynocephalus, and hybrids fall between. Minimal data on P. hamadryas and P. papio suggest an even lower response than P. cynocephalus. As HbF increases under stress, the ratio of I gamma to V gamma-chains changes from the value in the adult or juvenile baboon toward the ratio in the newborn baboon. However, it does not attain the newborn value. The V gamma A and V gamma C-genes respond differently to stress. In hybrids, the production of V gamma A-chains exceeds that of V gamma C-chains. A controlling factor in cis apparently is present and may be responsible for the species-related extent of total HbF production. It may be concluded that the more primitive the cell in the erythroid maturation series that has been subjected to 5-azacytidine, the more active is the I gamma-gene.

Amino Acid Sequence↗