5-azacytidine selectively increases gamma-globin synthesis in a patient with beta+ thalassemia

5-Azacytidine is a cytidine analogue that is capable of activating repressed genes in tissue-culture cells and has been shown to increase hemoglobin-F production in anemic baboons. This drug was administered to a patient with severe beta-thalassemia in an attempt to stimulate hemoglobin-F production. After seven days of 5-azacytidine treatment, gamma-globin synthesis increased approximately sevenfold, temporarily normalizing the patient's unbalanced globin synthesis. Erythropoiesis became more effective, leading to a temporary increase in the absolute reticulocyte count (from 5000 to 22,000 per cubic millimeter) and in hemoglobin concentration (from 8.0 to 10.8 g per deciliter). Hypomethylation of bone-marrow DNA near both the gamma-globin and epsilon-globin genes was directly demonstrated. At the time of peak drug effect, about 7000 gamma-globin messenger RNA molecules were present per erythroid bone-marrow cell, in contrast to 10 to 15 epsilon-globin messenger RNA molecules per cell. 5-Azacytidine selectivity increases gamma-globin synthesis and therefore provides a new approach to the treatment of severe beta-thalassemia. Further studies will be required to evaluate the efficacy, risks, and long-term toxicity of 5-azacytidine (or related compounds) before this approach can be used as a therapy for patients with disorders of hemoglobin synthesis.

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.

5-Azacytidine stimulates fetal hemoglobin synthesis in anemic baboons

In an attempt to stimulate Hb F synthesis in baboons by means other than erythropoietic stress, we considered the possibility that an agent that inhibits methylation of CpG sequences in DNA may be effective. 5-Azacytidine, a cytosine analogue that cannot be methylated, is such an agent. Animals whose packed red cell volume was maintained at approximately 20% by bleeding were given 10 daily intravenous injections of the drug (6 mg/kg) in 12 days. Hb F levels in these animals started to increase on day 5 of this regimen and peak levels, which were 6-30 times higher than those produced by bleeding alone, occurred 5-7 days after the last dose of the drug. In animals previously identified as genetically "high" or "low" Hb F responders, the maximal Hb F levels were 70-85% and 35-40% respectively. In dose-response studies 5-azacytidine given daily at 3-4 mg/kg produced maximal Hb F increases. The drug did not correlate the percentage (number) of Hb F-containing cells (F cells) beyond the maximal number achieved by bleeding alone and thus its main effect was to increase Hb F per F cell. The finding that Hb F synthesis can be modulated to such a high degree by a drug may have therapeutic implications--e.g., in sickle cell anemia, in which stimulation of Hb F synthesis may prevent sickling.

The US Peanut and Tree Nut Allergy Registry: characteristics of reactions in schools and day care

OBJECTIVE

Severe food-allergic reactions occur in schools, but the features have not been described.

STUDY DESIGN

Participants in the US Peanut and Tree Nut Allergy Registry (PAR) who indicated that their child experienced an allergic reaction in school or day care were randomly selected for a telephone interview conducted with a structured questionnaire.

RESULTS

Of 4586 participants in the PAR, 750 (16%) indicated a reaction in school or day care, and 100 subjects or parental surrogates described 124 reactions to peanut (115) or tree nuts (9); 64% of the reactions occurred in day care or preschool, and the remainder in elementary school or higher grades. Reactions were reported from ingestion (60%), skin contact/possible ingestion (24%), and inhalation/possible skin contact or ingestion (16%). In the majority of reactions caused by inhalation, concomitant ingestion/skin contact could not be ruled out. Various foods caused reactions by ingestion, but peanut butter craft projects were commonly responsible for the skin contact (44%) or inhalation (41%) reactions. For 90% of reactions, medications were given (86% antihistamines, 28% epinephrine). Epinephrine was given in school by teachers in 4 cases, nurses in 7, and parents or others in the remainder. Treatment delays were attributed to delayed recognition of reactions, calling parents, not following emergency plans, and an unsuccessful attempt to administer epinephrine.

CONCLUSIONS

School personnel must be educated to recognize and treat food-allergic reactions. Awareness must be increased to avoid accidental exposures, including exposure from peanut butter craft projects.

Peanut and tree nut allergic reactions in restaurants and other food establishments

BACKGROUND

The clinical features of food-allergic reactions in restaurants and other food establishments have not been studied. Of the registrants in the United States Peanut and Tree Nut Allergy Registry (PAR), 13.7% have reported reactions associated with such establishments.

OBJECTIVE

The purpose of this study was to determine the features of allergic reactions to peanut and tree nut in restaurant foods and foods purchased at other private establishments (eg, ice cream shops and bakeries).

METHODS

Telephone interviews were conducted through use of a structured questionnaire. Subjects/parental surrogates were randomly selected from among the 706 PAR registrants who reported a reaction in a restaurant or other food establishment.

RESULTS

Details were obtained for 156 episodes (29 first-time reactions) from 129 subjects/parental surrogates. Most reactions were caused by peanut (67%) or tree nut (24%); for some reactions (9%), the cause was a combination of peanut and another nut or was unknown. Symptoms began at a median of 5 minutes after exposure and were severe in 27% of reactions. Overall, 86% of reactions were treated (antihistamines, 86%; epinephrine, 40%). Establishments commonly cited were Asian food restaurants (19%), ice cream shops (14%), and bakeries/doughnut shops (13%). Among meal courses, desserts were a common cause (43%). Of 106 registrants with previously diagnosed allergy who ordered food specifically for ingestion by the allergic individual, only 45% gave prior notification about the allergy to the establishment. For 83 (78%) of these 106 reactions, someone in the establishment knew that the food contained peanut or tree nut as an ingredient; in 50% of these incidents, the food item was "hidden" (in sauces, dressings, egg rolls, etc), visual identification being prevented. In 23 (22%) of the 106 cases, exposures were reported from contamination caused primarily by shared cooking/serving supplies. In the remaining 21 subjects with previously diagnosed allergy, reactions resulted from ingestion of food not intended for them, ingestion of food selected from buffet/food bars, or skin contact/inhalation (residual food on tables, 2; peanut shells covering floors, 2; being within 2 feet of the cooking of the food, 1).

CONCLUSIONS

Restaurants and other food establishments pose a number of dangers for peanut- and tree nut-allergic individuals, particularly with respect to cross-contamination and unexpected ingredients in desserts and Asian food. Failure to establish a clear line of communication between patron and establishment is a frequent cause of errors.

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.

Histone deacetylase inhibitors increase p21(WAF1) and induce apoptosis of human myeloma cell lines independent of decreased IL-6 receptor expression

Histone deacetylase (HDAC) inhibitors cause growth arrest and apoptosis of cancer cells by both p21-dependent and independent mechanisms. Decreased expression of growth factor receptors may be a key factor in the p21-independent mechanism, although this has not been directly tested. We have tested the effects of sodium butyrate and trichostatin A on human myeloma cell lines and have observed G1 arrest and apoptosis associated with increased expression of p21(WAF1), Bax, Rb dephosphorylation, and decreased IL-6 receptor (IL-6R) expression. Experiments to determine the role of disruption of IL-6 signaling as a result of decreased IL-6 receptor expression in mediating these effects were conducted using a stable transfectant of the OPM-2 line which constitutively expressed the IL-6 receptor. Our results indicated that decreased IL-6R expression was not required for induction of p21(WAF1) or apoptosis. Thus, HDAC inhibitors appear to activate multiple cellular pathways, leading to growth arrest and apoptosis, and their use in the treatment of myeloma, particularly in combination with other agents, warrants further investigation.

Stimulation of fetal hemoglobin synthesis in baboons by hemolysis and hypoxia

Fetal hemoglobin (Hb F) levels in the peripheral blood of baboons (Papio cynocephalus) increased from an average value of 0.78% to 18.1% during the recovery phase from phenylhydrazine-induced hemolytic anemia. A similar increase was observed in animals exposed to hypobaric hypoxia. Large individual variations in the maximal Hb F levels were observed which could not be correlated with the ages of the animals. Reinduction of hemolysis in two fully recovered animals resulted in Hb F levels that were of similar magnitude as in the preceding episode, suggesting the possibility of genetically determined individual variations in the rate of Hb F synthesis under the same conditions of erythropoietic stimulation. Reticulocytes from the animals subjected to hemolysis of hypobaric hypoxia synthesized similar absolute quantities of Hb F in vitro. The results of the present studies indicate that the physiological switch from the synthesis of Hb F to that of Hb A during ontogeny can be reversed in adult nonhuman primates by conditions of erythropoietic stress known to be associated with high erythropoietin levels. These findings open the possibility that Hb F synthesis in adult humans may be therapeutically modulated in individuals who might benefit from increased levels of Hb F, such as patients with sickle cell anemia.

Higher fat stores contribute to persistence of little brown bat populations with white-nose syndrome

The persistence of populations declining from novel stressors depends, in part, on their ability to respond by trait change via evolution or plasticity. White-nose syndrome (WNS) has caused rapid declines in several North America bat species by disrupting hibernation behaviour, leading to body fat depletion and starvation. However, some populations of Myotis lucifugus now persist with WNS by unknown mechanisms. We examined whether persistence of M. lucifigus with WNS could be explained by increased body fat in early winter, which would allow bats to tolerate the increased energetic costs associated with WNS. We also investigated whether bats were escaping infection or resistant to infection as an alternative mechanism explaining persistence. We measured body fat in early and late winter during initial WNS invasion and 8 years later at six sites where bats are now persisting. We also measured infection prevalence and intensity in persisting populations. Infection prevalence was not significantly lower than observed in declining populations. However, at two sites, infection loads were lower than observed in declining populations. Body fat in early winter was significantly higher in four of the six persisting populations than during WNS invasion. Physiological models of energy use indicated that these higher fat stores could reduce WNS mortality by 58%-70%. These results suggest that differences in fat storage and infection dynamics have reduced the impacts of WNS in many populations. Increases in body fat provide a potential mechanism for management intervention to help conserve bat populations.

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.

Human immunodeficiency virus type 1-infected persons with residual disease and virus reservoirs on suppressive highly active antiretroviral therapy can be stratified into relevant virologic and immunologic subgroups

A significant percentage of human immunodeficiency virus type 1 (HIV-1)-infected persons treated with highly active antiretroviral therapy (HAART) will develop plasma HIV-1-specific virion RNA levels <50 copies/mL. HIV-1-infected persons receiving virally suppressive HAART were studied with a viral outgrowth assay of the patients' peripheral blood mononuclear cells (PBMC), and a quantitative polymerase chain reaction assay was used to analyze HIV-1 2-long terminal repeat (2-LTR) circular DNA in PBMC, which indicates new HIV-1 infections of cells in vivo. Viral outgrowth in vitro correlated inversely with the level of peripheral blood CD4(+) T lymphocytes. Detection and quantitation of 2-LTR circular DNA correlated strongly with viral outgrowth patterns and inversely with CD4(+) T lymphocyte counts. Relevant subgroups of HIV-1-infected subjects on suppressive HAART with residual viral disease and reservoirs can now be stratified.

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.

Genetic relationship between fetal Hb levels in normal and erythropoietically stressed baboons

Previous studies have shown that the magnitude of the fetal haemoglobin (Hb F) response to haemolytic anaemia and hypobaric hypoxia in the baboon is specific to an animal ('high and low Hb F responders'), suggesting that the Hb F response is under genetic control. In this study Hb F levels in 55 adult (over 8 years old) and 23 juvenile unstressed baboons varied between 0.02% and 0.6% ('resting Hb F levels'). Twenty-nine of these animals were subjected to haemolytic stress and the magnitude of their Hb F response was positively correlated with the resting Hb F levels. In addition, the resting levels of Hb F in parents were positively correlated with those of their offspring. In 11 animals, seven adults and four juveniles, subjected to haemopoietic stress the Hb F levels were increased proportionally to the number of F-cells. In juvenile animals the calculated concentration of Hb F per F-cell was markedly higher than in adult animals. These data demonstrate that the resting level of Hb F is predictive of the magnitude of the Hb F response to stress erythropoiesis. The number of F-cells and the concentration of Hb F per cell in erythropoietic stress appear to be modulated by different mechanisms.

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.

Effects of hydroxurea, stem cell factor, and erythropoietin in combination on fetal hemoglobin in the baboon

OBJECTIVE

Augmentation of the level of fetal hemoglobin (HbF) is considered therapeutic for patients with sickle cell disease. The objective of this study was to determine the effect of treatment with a combination of erythropoietin (Epo), stem cell factor (SCF), and hydroxyurea (HU) on HbF levels.

MATERIALS AND METHODS

The effect of treatment with a combination of Epo, SCF, and HU on HbF, F-cell numbers, and globin chain synthesis was evaluated in a baboon model.

RESULTS

Treatment with a combination of SCF+Epo resulted in a two-fold increase in HbF, F-cells, and F-reticulocytes compared to Epo alone. The combination of SCF+Epo+HU resulted in an additional two-fold increase in HbF, whereas F-cells and F-reticulocytes increased only 25% compared to the SCF+Epo regimen. Measurement of differential globin chain synthesis indicated that the SCF+Epo+HU treatment also increased the I gamma/V gamma (homologous to human G gamma and A gamma) synthetic ratio toward the fetal ratio.

CONCLUSIONS

HU can effectively augment growth factor-induced HbF synthesis in vivo. Because I gamma/V gamma ratios are unaffected by erythropoietic stress and similar increases in this ratio have only been observed following administration of 5-azacytidine, we suggest that these two agents may share a common mechanism of action involving the recruitment of a similar target cell population to terminal erythroid differentiation.

Magnitude of the fetal hemoglobin response to acute hemolytic anemia in baboons is controlled by genetic factors

When hemolytic anemia was induced in 26 baboons (Papio cynocephalus), aged 7-22 mo, they increased their production of fetal hemoglobin (HbF). Although the resulting reduction in hematocrits and increases of reticulocyte counts were similar in all stressed animals there was marked variability in the maximal rates of HbF synthesis. The maximal levels of HbF attained appeared to fall into three separate groups: low, intermediate, and high. These differences were not related to sex or several measures of erythrocyte metabolism. Animals exposed to repeated episodes of erythropoietic stress after full hematologic recovery demonstrated some variability in their maximal HbF levels attained from one episode to another, but these variations never extended to adjacent classes. The described biochemical and mating data suggest that the magnitude of the HbF response to hemolytic anemia is controlled by genetic factors.

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.

betaS Chain turnover in reticulocytes of sickle trait individuals with high or low concentrations of haemoglobin S

Reticulocytes, isolated from the blood of sickle cell trait donors with either low (25-30%) or high (40-42%) haemoglobin S(Hb S) concentrations, were incubated with [3H]leucine for various times from 1.25 to 60 min. Samples of the total soluble fractions of the cells were denatured with urea and mercaptoethanol. The mixtures were analysed by electrophoresis on cellulose acetate strips. The specific radioactivities (dpm/mg) of the separated betaS and betaA globin chains were determined. The betaS/betaA ratios of globin chain specific radio activities in the reticulocytes of the 'low Hb S' donors decreased gradually from initial values higher than 1.30 to values near unity. These data suggested that faster turnover of some of the soluble, newly synthesized betaS chains compared to the newly synthesized betaA chains could explain part, but not all, of the disparity in concentrations of Hbs S and A in these people. When reticulocytes from 'high Hb S' donors were 3H-labelled for times longer than 5 min, the betaS/betaA specific radioactivity ratios remained at or near unity. This result suggested that newly synthesized betaS chains were not turning over selectively in these cells. Instead, there was a relative decrease in betaS chain synthesis proportional to the difference in blood concentrations of Hb S and Hb A. Additional calculations suggested that the more rapid turnover of newly synthesized betaS chains in the 'low Hb S' reticulocytes could explain the difference in Hb S concentrations between 'high and low Hb S' people. These results are consistent with previous reports that an alpha-thalassaemia gene, present in 'low Hb S' but absent in 'high Hb S' donors, may be responsible for the selective turnover of betaS chains.