Mesenchymal progenitors aging highlights a miR-196 switch targeting HOXB7 as master regulator of proliferation and osteogenesis.

Human aging is associated with a decrease in tissue functions combined with a decline in stem cells frequency and activity followed by a loss of regenerative capacity. The molecular mechanisms behind this senescence remain largely obscure, precluding targeted approaches to counteract aging. Focusing on mesenchymal stromal/stem cells (MSC) as known adult progenitors, we identified a specific switch in miRNA expression during aging, revealing a miR-196a upregulation which was inversely correlated with MSC proliferation through HOXB7 targeting. A forced HOXB7 expression was associated with an improved cell growth, a reduction of senescence, and an improved osteogenesis linked to a dramatic increase of autocrine basic fibroblast growth factor secretion. These findings, along with the progressive decrease of HOXB7 levels observed during skeletal aging in mice, indicate HOXB7 as a master factor driving progenitors behavior lifetime, providing a better understanding of bone senescence and leading to an optimization of MSC performance.

Mesenchymal progenitors expressing TRAIL induce apoptosis in sarcomas.

Sarcomas are frequent tumors in children and young adults that, despite a relative chemo-sensitivity, show high relapse rates with up to 80% of metastatic patients dying in 5 years from diagnosis. The real ontogeny of sarcomas is still debated and evidences suggest they may derive from precursors identified within mesenchymal stromal/stem cells (MSC) fractions. Recent studies on sarcoma microenvironment additionally indicated that MSC could take active part in generation of a supportive stroma. Based on this knowledge, we conceived to use modified MSC to deliver tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) targeting different sarcoma histotypes. Gene modified MSC expressing TRAIL were cocultured with different osteosarcoma, rhabdomyosarcoma, and Ewing's Sarcoma (ES) cell lines assessing viability and caspase-8 activation. An in vivo model focused on ES was then implemented considering the impact of MSC-TRAIL on tumor size, apoptosis, and angiogenesis. MSC expressing TRAIL induced significantly high apoptosis in all tested lines. Sarcoma death was specifically associated with caspase-8 activation starting from 8 hours of coculture with MSC-TRAIL. When injected into pre-established ES xenotransplants, MSC-TRAIL persisted within its stroma, causing significant tumor apoptosis versus control groups. Additional histological and in vitro studies reveal that MSC-TRAIL could also exert potent antiangiogenic functions. Our results suggest that MSC as TRAIL vehicles could open novel therapeutic opportunities for sarcoma by multiple mechanisms.

Mesenchymal stem/stromal cells as a delivery platform in cell and gene therapies.

Regenerative medicine relying on cell and gene therapies is one of the most promising approaches to repair tissues. Multipotent mesenchymal stem/stromal cells (MSC), a population of progenitors committing into mesoderm lineages, are progressively demonstrating therapeutic capabilities far beyond their differentiation capacities. The mechanisms by which MSC exert these actions include the release of biomolecules with anti-inflammatory, immunomodulating, anti-fibrogenic, and trophic functions. While we expect the spectra of these molecules with a therapeutic profile to progressively expand, several human pathological conditions have begun to benefit from these biomolecule-delivering properties. In addition, MSC have also been proposed to vehicle genes capable of further empowering these functions. This review deals with the therapeutic properties of MSC, focusing on their ability to secrete naturally produced or gene-induced factors that can be used in the treatment of kidney, lung, heart, liver, pancreas, nervous system, and skeletal diseases. We specifically focus on the different modalities by which MSC can exert these functions. We aim to provide an updated understanding of these paracrine mechanisms as a prerequisite to broadening the therapeutic potential and clinical impact of MSC.

Megakaryocytes promote murine osteoblastic HSC niche expansion and stem cell engraftment after radioablative conditioning.

Successful hematopoietic stem cell (HSC) transplantation requires donor HSC engraftment within specialized bone marrow microenvironments known as HSC niches. We have previously reported a profound remodeling of the endosteal osteoblastic HSC niche after total body irradiation (TBI), defined as relocalization of surviving megakaryocytes to the niche site and marked expansion of endosteal osteoblasts. We now demonstrate that host megakaryocytes function critically in expansion of the endosteal niche after preparative radioablation and in the engraftment of donor HSC. We show that TBI-induced migration of megakaryocytes to the endosteal niche depends on thrombopoietin signaling through the c-MPL receptor on megakaryocytes, as well as CD41 integrin-mediated adhesion. Moreover, niche osteoblast proliferation post-TBI required megakaryocyte-secreted platelet-derived growth factor-BB. Furthermore, blockade of c-MPL-dependent megakaryocyte migration and function after TBI resulted in a significant decrease in donor HSC engraftment in primary and competitive secondary transplantation assays. Finally, we administered thrombopoietin to mice beginning 5 days before marrow radioablation and ending 24 hours before transplant to enhance megakaryocyte function post-TBI, and found that this strategy significantly enhanced donor HSC engraftment, providing a rationale for improving hematopoietic recovery and perhaps overall outcome after clinical HSC transplantation.

In vitro differentiation of human amniotic epithelial cells into insulin-producing 3D spheroids.

Regenerative medicine and stem cell therapy may represent the solution for the treatment of non-curable human diseases such as type 1 diabetes. In this context of growing demand for functional and safe stem cells, human amniotic epithelial cells (hAECs) from term placenta have attracted increasing interest for their wide availability, stem cell properties, and differentiation plasticity, which make them a promising tool for stem cell-based therapeutic applications. We initially assayed the stemness characteristics of hAECs in serum-free conditions. Subsequently we developed a culture procedure on extracellular matrix for the formation of three-dimensional (3D) spheroids. Finally, we tested the immunomodulation and differentiation potential of hAEC spheroids: the presence of pancreatic endocrine hormones was revealed with transmission electron microscopy and immunofluorescence analyses; the release of C-peptide in hyperglycemic conditions was assayed with ELISA. The serum-free culture conditions we applied proved to maintain the basic stemness characteristics of hAECs. We also demonstrated that 3D spheroids formed by hAECs in extracellular matrix can be induced to differentiate into insulin-producing cells. Finally, we proved that control and induced cells equally inhibit the proliferation of activated mononuclear cells. The results of this study highlight the properties of amnion derived epithelial cells as promising and abundant source for cell-based therapies. In particular we are the first group to show the in vitro pancreatic induction of hAECs cultured on extracellular matrix in a 3D fashion. We accordingly propose the outcomes of this study as a novel contribution to the development of future cell replacement therapies involving placenta-derived cells.

IGF-1-mediated osteoblastic niche expansion enhances long-term hematopoietic stem cell engraftment after murine bone marrow transplantation.

The efficiency of hematopoietic stem cell (HSC) engraftment after bone marrow (BM) transplantation depends largely on the capacity of the marrow microenvironment to accept the transplanted cells. While radioablation of BM damages osteoblastic stem cell niches, little is known about their restoration and mechanisms governing their receptivity to engraft transplanted HSCs. We previously reported rapid restoration and profound expansion of the marrow endosteal microenvironment in response to marrow radioablation. Here, we show that this reorganization represents proliferation of mature endosteal osteoblasts which seem to arise from a small subset of high-proliferative, relatively radio-resistant endosteal cells. Multiple layers of osteoblasts form along the endosteal surface within 48 hours after total body irradiation, concomitant with a peak in marrow cytokine expression. This niche reorganization fosters homing of the transplanted hematopoietic cells to the host marrow space and engraftment of long-term-HSC. Inhibition of insulin-like growth factor (IGF)-1-receptor tyrosine kinase signaling abrogates endosteal osteoblast proliferation and donor HSC engraftment, suggesting that the cytokine IGF-1 is a crucial mediator of endosteal niche reorganization and consequently donor HSC engraftment. Further understanding of this novel mechanism of IGF-1-dependent osteoblastic niche expansion and HSC engraftment may yield clinical applications for improving engraftment efficiency after clinical HSC transplantation.

Final height and body mass index in adult survivors of childhood acute lymphoblastic leukemia treated without cranial radiotherapy: a retrospective longitudinal multicenter Italian study.

BACKGROUND: Young adult survivors of childhood acute lymphoblastic leukemia (ALL) treated with protocols including cranial radiotherapy demonstrate a persistent weight gain and reduced final height. Published reports on the effects on growth of different oncologic therapies are conflicting and difficult to interpret because they combined children treated with both cranial irradiation and multi-agent chemotherapy. Our study investigated the effect of chemotherapy alone on body mass index (BMI) and on growth at the achievement of final height in a homogeneous cohort of Italian childhood ALL survivors. METHODS: We retrospectively studied 162 Caucasian patients treated on the Italian Association of Pediatric Hematology and Oncology protocols without radiotherapy between 1989 and 2000 at five Italian centers with 107 inclusions (58 males). Height- and BMI-standard deviation score (SDS) were collected at diagnosis of ALL, at the end of treatment and at the achievement of final height. Changes in height SDS and BMI SDS with time were analyzed using dependent sample Student's t-test. RESULTS: A significant reduction of height-SDS was documented during treatment in both genders. This reduction of height-SDS was not followed by an appropriate catch-up growth, despite the achievement of a mean final height within the normal range. At diagnosis females showed a lower mean BMI-SDS than males. During treatment, in the whole population, BMI-SDS increased significantly. After it, while males lost BMI-SDS, females showed its persistent increase. CONCLUSIONS: Survivors of childhood ALL generally seemed to achieve a normal final height with a BMI within the normal range. These parameters appeared to be only minimally affected by chemotherapy. Nevertheless, height catch-up growth was not completed after chemotherapy in both genders and all patients experienced an increase of BMI-SDS during chemotherapy that only females seemed to conserve until the achievement of final height.

Paraplegia by spinal cord compression as the initial manifestation of Hodgkin's disease: a case report.

The 90% of Hodgkin's disease (HD) cases are originated by lymphnodes whereas 10% by extranodal regions as epidural space. Neurologic complications of HD can be classified as directly resulting from the disease or indirectly originated from the disease or from its treatment. Patients very rarely present with spinal cord compression (SCC)  due to epidural HD. Few cases of HD with such presentation have been reported in the literature. Primary spinal extradural HD with no further organ involvement is extremely rare. We report a case of a child with SCC as initial and unique presentation of HD.

Delayed marrow infusion in mice enhances hematopoietic and osteopoietic engraftment by facilitating transient expansion of the osteoblastic niche.

Transplantation of bone marrow cells leads to engraftment of osteopoietic and hematopoietic progenitors. We sought to determine whether the recently described transient expansion of the host osteoblastic niche after marrow radioablation promotes engraftment of both osteopoietic and hematopoietic progenitor cells. Mice infused with marrow cells 24 hours after total body irradiation (TBI) demonstrated significantly greater osteopoietic and hematopoietic progenitor chimerism than did mice infused at 30 minutes or 6 hours. Irradiated mice with a lead shield over 1 hind limb showed greater hematopoietic chimerism in the irradiated limb than in the shielded limb at both the 6- and 24-hour intervals. By contrast, the osteopoietic chimerism was essentially equal in the 2 limbs at each of these intervals, although it significantly increased when cells were infused 24 hours compared with 6 hours after TBI. Similarly, the number of donor phenotypic long-term hematopoietic stem cells was equivalent in the irradiated and shielded limbs after each irradiation-to-infusion interval but was significantly increased at the 24-hour interval. Our findings indicate that a 24-hour delay in marrow cell infusion after TBI facilitates expansion of the endosteal osteoblastic niche, leading to enhanced osteopoietic and hematopoietic engraftment.

Adipose stromal/stem cells assist fat transplantation reducing necrosis and increasing graft performance.

Autologous fat transfer (AFT) is a procedure for adipose tissue (AT) repair after trauma, burns, post-tumor resections and lipodystrophies still negatively impacted by the lack of graft persistence. The reasons behind this poor outcome are unclear and seem to involve damages in either harvested/transplanted mature adipocytes or on their mesenchymal progenitors, namely adipose stromal/stem cells (ASC), and due to post-transplant AT apoptosis and involution. A rabbit subcutaneous AT regeneration model was here developed to first evaluate graft quality at different times after implant focusing on related parameters, such as necrosis and vasculogenesis. Standard AFT was compared with a strategy where purified autologous ASC, combined with hyaluronic acid (HA), assisted AFT. Five million of autologous ex vivo isolated CD29+, CD90+, CD49e+ ASC, loaded into HA, enriched 1 ml of AT generating an early significant protective effect in reducing AFT necrosis and increasing vasculogenesis with a preservation of transplanted AT architecture. This beneficial impact of ASC assisted AFT was then confirmed at three months with a robust lipopreservation and no signs of cellular transformation. By a novel ASC assisted AFT approach we ensure a reduction in early cell death favoring an enduring graft performance possibly for a more stable benefit in patients.

Dancing eye syndrome as first symptom of neuroblastoma.

BACKGROUND: "Dancing eye syndrome", also called Kinsbourne syndrome or Opsoclonus-Myoclonus-Ataxia Syndrome (OMS) is a rare neurological disorder that in children is frequently associated to occult, low-grade neuroblastoma (NB) (>50% of the cases). OMS may also be triggered by infections and it is often associated to developmental impairment and disability. CASE PRESENTATION: We discuss the case of a 16 months old female with acutely onset of OMS associated to occult stage III NB. CONCLUSIONS: OMS represents a diagnostic challenge for pediatric clinicians. The suspect of OMS imposes the search for an occult NB in order to promptly treat a life-threatening event like tumor and to prevent the neurological sequels linked to OMS.

Epidemiology of infections in children with acquired aplastic anaemia: a retrospective multicenter study in Italy.

Infection is a significant cause of death in patients with aplastic anaemia (AA). However, few studies have examined the characteristics of infections in patients with AA, especially in children. The aim of this retrospective study was to evaluate the incidence and types of infections in a large cohort of paediatric patients with AA referred to eight AIEOP (Italian Association of Paediatric Oncology and Haematology) centres in Italy. The study included 78 patients, 45 boys and 33 girls, median age 9.29 yrs (1st-3rd quartile 3.59-13.09) diagnosed with AA. During the study period, 111 infectious episodes were observed in 42 (54%) patients. Fifty-one (46%) episodes were fever of unknown origin and 60 (54%) were documented infections (DI). In this group, microbiologically documented infection (MDI) with bacteremia accounted for 23 (38%) episodes, MDI without bacteremia for 7 (12%), clinically documented infection for 25 (42%) and invasive fungal diseases for 5 (8%). The rate (episodes/1000 d at risk) was similar in severe aplastic anemia and very severe aplastic anemia both before and after day 120. During the first 120 d from diagnosis, the cumulative risk of a DI was 21% (95% CI 12-29) with the last episode at day 117, but the 50% of episodes were observed in the first 24 d. After day 120, the cumulative risk of DI was again 21% (95% CI 12-29), with the last episode at day 445 of follow-up, with 50% of episodes observed in the first 120 d of observation (240 d from the diagnosis of AA). We found a statistically significant association between the grade of aplasia at diagnosis and the incidence of IEs (P = 0.0002). No association was found between gender, age at diagnosis, response at day +120 and at day +180, use of G-CSF and occurrence of IEs. The actuarial overall survival at 5 yrs was 90% ± 3.6. The mortality rate attributable to infection complication was 9%. This is a large paediatric cohort study reporting the epidemiology of infectious complications in children with AA and that allow us to compare the epidemiological data in this diseases with that of the most recent studies in neutropenic children with cancer. Our findings confirm that infections represent the main cause of death in patients with AA and they are important for the design of management strategies of febrile neutropenia in these patients.

Leukemia risk in children exposed to benzene and PM10 from vehicular traffic: a case-control study in an Italian population.

Benzene, a recognized occupational leukemogen in adults, has been hypothesized to also increase the risk of childhood leukemia. We carried out a population-based case-control study in a northern Italy community involving 83 cases with acute childhood leukemia diagnosed in the years 1998-2009 and 332 matched controls. We assessed residential exposure to benzene and to particulate matter ≤10 µm (PM10) from motorized traffic using geocoded residences and detailed emission and dispersion modeling. Exposure to benzene, and to a lesser extent to PM10, appeared to be independently associated with an excess leukemia risk. When we stratified the study population by age and by leukemia subtype, the relative risk associated with benzene exposure was higher among children aged less than 5 years, and despite small numbers this relation appeared to be considerably stronger for acute myeloid leukemia than for acute lymphoblastic leukemia. Overall, these findings suggest that exposure to low levels of benzene released from motorized traffic may increase the risk of childhood leukemia, and suggest a possible independent effect of PM10, although unmeasured confounding due to other pollutants cannot be ruled out.

Incidental diagnosis of thoracic ganglioneuroblastoma in a 3-year-old female with wheezing.

Ganglioneuroblastoma (GNB) is a cancer of the peripheral sympathetic nervous system and represents the 30% of cases of Neuroblastoma. When originates from thoracic ganglia it may appear very late, with severe symptoms like respiratory distress or neurological dysfunctions. We present an incidental diagnosis of thoracic GNB, discovered by a chest radiography during a recurrent wheezing unresponsive to bronchodilators. The early diagnosis allowed a precocious treatment probably improving the outcome.

Restoration and reversible expansion of the osteoblastic hematopoietic stem cell niche after marrow radioablation.

Adequate recovery of hematopoietic stem cell (HSC) niches after cytotoxic conditioning regimens is essential to successful bone marrow transplantation. Yet, very little is known about the mechanisms that drive the restoration of these niches after bone marrow injury. Here we describe a profound disruption of the marrow microenvironment after lethal total body irradiation of mice that leads to the generation of osteoblasts restoring the HSC niche, followed by a transient, reversible expansion of this niche. Within 48 hours after irradiation, surviving host megakaryocytes were observed close to the endosteal surface of trabecular bone rather than in their normal parasinusoidal site concomitant with an increased stromal-derived factor-1 level. A subsequent increase in 2 megakaryocyte-derived growth factors, platelet-derived growth factor-beta and basic fibroblast growth factor, induces a 2-fold expansion of the population of N-cadherin-/osteopontin-positive osteoblasts, relative to the homeostatic osteoblast population, and hence, increases the number of potential niches for HSC engraftment. After donor cell engraftment, this expanded microenvironment reverts to its homeostatic state. Our results demonstrate the rapid recovery of osteoblastic stem cell niches after marrow radioablation, provide critical insights into the associated mechanisms, and suggest novel means to manipulate the bone marrow microenvironment to promote HSC engraftment.

Pediatric pharmacogenetic and pharmacogenomic studies: the current state and future perspectives.

Genetic differences among individuals can explain some of the variability observed during drug treatment. Many studies have correlated the different pharmacological response to genetic variability, but most of them have been conducted on adult populations. Much less attention has been given to the pediatric population. Pediatric patients constitute a vulnerable group with regard to rational drug prescribing since they present differences arising from the various stages of development. However, only a few steps have been made in developmental pharmacogenomics. This review attempts to describe the current methods for pharmacogenetic and pharmacogenomic studies, providing some of the most studied examples in pediatric patients. It also gives an overview on the implication and importance of microRNA polymorphisms, transcriptomics, metabonomics, and proteomics in pharmacogenetics and pharmacogenomics studies.

Endpoints in paediatric oncology.

PURPOSE: The purpose of this review is to address the issue of endpoints in paediatric oncology. Oncologists use this term to refer to an outcome they are trying to measure with a clinical trial, which may become accordingly the object of scientific articles. The outcome measured may concern both efficacy and safety, although from different perspectives. METHODS: Based on both literature and experience developed in clinical trials, the different types of endpoints have been critically analysed in their power to provide the highest information of therapeutic interest (efficacy and safety) with the least risk and discomfort for the individual. Primary, secondary and surrogate endpoints have been distinguished. The most relevant differences have been discussed in comparison with adult oncology settings of endpoints. RESULTS: The rarity of cancer in childhood and adolescence and the objective difficulty of enrolling statistically conceivable numbers of individuals have determined the utmost positive development of large scale, multinational clinical trials. The most interesting consequence is that the impact of multiplicity interferences, which is usually present in virtually all clinical trials developed for adults with cancer, is not a common event in paediatric oncology. Nevertheless, many of the questions concerning the different impact on outcome and survival of clinical trials developed in adult oncology remain unanswered due to the objective limitations still existing in terms of cure compared with paediatric oncology. The powerful consistency of cure rate, as the most relevant endpoint of clinical trials developed in paediatric oncology, addresses additional considerations to support the relevant differences existing between adult and paediatric oncology: both the development of clinical trials with different aims (confirmatory versus primary response) and the limited impact of multiplicity limitations may determine different implications regarding the meaning of endpoints in paediatric and adult oncology. CONCLUSION: The aim of cancer treatment is to improve survival (SUR) and quality of life (QoL), but some restraints on the conduct of clinical trials may make these goals unattainable. Clinical trial endpoints represent a measure method aimed to grant answers to questions addressed by the clinical trial itself. The effect of the new regulation is expected to stimulate high-quality research and provide robust information on paediatric drugs to increase the availability of such drugs to children.

Identification of Enterococcus mundtii as a pathogenic agent involved in the "flacherie" disease in Bombyx mori L. larvae reared on artificial diet.

Enterococcus mundtii was shown to be directly correlated with flacherie disease of the silkworm larvae reared on artificial diet supplemented with chloramphenicol. Its identification was carried out by means of light and electron microscopy and nucleotide sequencing of 16S gene. The bacterium is capable of rapidly multiplying in the silkworm gut and of invading other body tissues, as demonstrated by deliberate infection of germfree larvae and by subsequent TEM observations. E. mundtii can endure alkaline pH of the silkworm gut and it has been proved to adapt in vitro to commonly applied doses of chloramphenicol, whose use can further contribute to reduce competition by other bacteria in Bombyx mori alimentary canal. The modality of transmission of the infection to the larvae was among the objectives of the present research. Since contamination of the progeny by mother moths can be avoided through routine egg shell disinfection, a trans-ovarian vertical transmission can be ruled out. On the other hand the bacterium was for the first time identified on mulberry leaves, and therefore artificial diet based on leaf powder could be a source of infection. We showed that while microwaved diet could contain live E. mundtii cells, the autoclaved diet is safe in this respect. Being E. mundtii also part of the human-associated microbiota, and since B. mori is totally domestic species, a possible role of man in its epidemiology can be postulated.

GMP-manufactured density gradient media for optimized mesenchymal stromal/stem cell isolation and expansion.

BACKGROUND AIMS: Bone marrow (BM) mesenchymal stromal/stem cells (MSC) are therapeutic tools in regenerative medicine and oncology. MSC isolation is often performed starting from a separation step based on research-grade 1.077 g/mL density gradient media (DGM). However, MSC clinical application should require the introduction of good manufacturing practice (GMP) reagents. We took advantage of two novel GMP DGM with densities of 1.077 and 1.073 g/mL (Ficoll-Paque PREMIUM and Ficoll-Paque PREMIUM 1.073, respectively) to test whether these reagents could isolate MSC efficiently while simultaneously comparing their performance. METHODS: BM samples were processed using either 1.077 or 1.073 g/mL GMP DGM. BM mononucleated cell (MNC) fractions were analyzed for viability, immunophenotype, clonogenic potential, ex vivo expansion and differentiation potential. RESULTS: No differences were noticed in cell recovery and viability between the groups. Fluorescence-activated cell-sorting (FACS) analyzes on freshly isolated cells indicated that the 1.073 g/mL GMP DGM more efficiently depleted the CD45(+) fraction in comparison with 1.077 GMP DGM. Moreover, in the 1.073 group, fibroblastic colony-forming units (CFU-F) were 1.5 times higher and the final MSC yield 1.8 times increased after four passages. Both reagents isolated MSC with the expected phenotype; however, 1.073-isolated MSC showed a higher expression of CD90, CD146 and GD2. Additionally, MSC from both groups were capable of fully differentiating into bone, adipose cells and cartilage. CONCLUSIONS: Both GMP DGM enriched MSC from BM samples, suggesting that these reagents would be suitable for clinical-grade expansions. In addition, the density of 1.073 g/mL provides a significant advantage over 1.077 g/mL GMP DGM, impacting the quantity of MSC obtained and reducing the ex vivo expansion time for optimized cell-based clinical applications.

Risk of hematological malignancies associated with magnetic fields exposure from power lines: a case-control study in two municipalities of northern Italy.

BACKGROUND: Some epidemiologic studies have suggested an association between electromagnetic field exposure induced by high voltage power lines and childhood leukemia, but null results have also been yielded and the possibility of bias due to unmeasured confounders has been suggested. METHODS: We studied this relation in the Modena and Reggio Emilia municipalities of northern Italy, identifying the corridors along high voltage power lines with calculated magnetic field intensity in the 0.1-<0.2, 0.2-<0.4, and > or = 0.4 microTesla ranges. We identified 64 cases of newly-diagnosed hematological malignancies in children aged <14 within these municipalities from 1986 to 2007, and we sampled four matched controls for each case, collecting information on historical residence and parental socioeconomic status of these subjects. RESULTS: Relative risk of leukemia associated with antecedent residence in the area with exposure > or = 0.1 microTesla was 3.2 (6.7 adjusting for socioeconomic status), but this estimate was statistically very unstable, its 95% confidence interval being 0.4-23.4, and no indication of a dose-response relation emerged. Relative risk for acute lymphoblastic leukemia was 5.3 (95% confidence interval 0.7-43.5), while there was no increased risk for the other hematological malignancies. CONCLUSIONS: Though the number of exposed children in this study was too low to allow firm conclusions, results were more suggestive of an excess risk of leukemia among exposed children than of a null relation.