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Biomedical subjects

Isaac Yaniv

Publications and source records attributed to Isaac Yaniv.

At least 19 recordsLinked to original sources
PubMed2006

Risk factors for future development of systemic lupus erythematosus in children with idiopathic thrombocytopenic purpura.

The risk of later development of systemic lupus erythematosus (SLE) in childhood idiopathic thrombocytopenic purpura (ITP) is currently unknown. We retrospectively evaluated the incidence and risk factors of this complication in 222 children with ITP who were followed for a mean of 4.2+/-4.9 years. During that time 3.6% of the children (8/222) developed SLE; all were females with positive anti-nuclear antibody (ANA), older (12.7+/-3.6 vs. 6.4+/-4.3 years old; P<0.01), and were more likely to have chronic ITP (87.5 vs. 46%; P=0.02), and had high titers of ANA. The majority of children with ITP who had a positive ANA (14/22, 64%) did not develop SLE.

Antibodies, Antinuclear↗
PubMed2006

Successful treatment of Wolman disease by unrelated umbilical cord blood transplantation.

Wolman disease is a rapidly fatal lysosomal storage disease caused by the complete absence of lysosomal acid lipase activity. We report the cure of an infant with Wolman disease following transplantation of unrelated HLA-mismatched umbilical cord blood-derived stem cells. Umbilical cord blood was chosen as the stem-cell source because of its immediate availability and reduced tendency to cause graft-versus-host disease. The transplantation resulted in restoration of normal acid lipase levels before the onset of permanent end-organ damage. Four years after transplantation, the patient is thriving and has normal levels of acid lipase in peripheral blood cells. To our knowledge, this is the first report of a successful unrelated cord blood transplant in a patient with Wolman disease. Umbilical cord stem cells transplantation can restore acid lipase levels in Wolman disease, and if performed early, can cure the disease.

Brain↗
PubMed2006

Telomere length is a prognostic factor in neuroblastoma.

BACKGROUND: Maintenance of telomeres, in most instances by reactivation of telomerase, is obligatory for the indefinite proliferation of tumor cells. The objective of this study was to evaluate telomere length and telomerase activity (TA) as markers for progression and prognosis in neuroblastoma. METHODS: Primary tumor samples from 51 patients were analyzed for telomere length and TA and were correlated with known prognostic parameters and outcome. RESULTS: Telomere length had a highly significant correlation with prognosis (P = .007). Short telomeres were predictive of a favorable prognosis, whereas long or unchanged telomeres were predictive of a poor outcome. For the first time to their knowledge, the authors have shown that, within the high-risk group patients, telomere length could define a favorable subgroup that had a progression-free survival (PFS) rate of 86% compared with a PFS rate of 36% for patients with more adverse disease, which is the expected PFS rate for such patients (P = .04). In a multivariate analysis, telomere length was the most significant prognostic parameter (P = .032). TA was correlated significantly with outcome and with known prognostic factors. High TA and low TA were associated with adverse and favorable outcomes, respectively (P = .01). CONCLUSION: The results of this investigation suggested that telomere length is a highly significant prognostic parameter of clinical relevance in patients with neuroblastoma. In high-risk patients, telomere length was the sole significant parameter that identified a group of patients who had a favorable prognosis. The authors suggest that telomere length should be included in the recommended diagnostic investigations for patients with neuroblastoma.

Blotting, Southern↗
PubMed2006

Does physiological beta cell turnover initiate autoimmune diabetes in the regional lymph nodes?

The initial immune process that triggers autoimmune beta cell destruction in type 1 diabetes is not fully understood. In early infancy there is an increased beta cell turnover. Recurrent exposure of tissue-specific antigens could lead to primary sensitization of immune cells in the draining lymph nodes of the pancreas. An initial immune injury to the beta cells can be inflicted by several cell types, primarily macrophages and T cells. Subsequently, infiltrating macrophages transfer antigens exposed by apoptotic beta cells to the draining lymph nodes, where antigen presenting cells process and amplify a secondary immune reaction. Antigen presenting cells evolve as dual players in the activation and suppression of the autoimmune reaction in the draining lymph nodes. We propose a scenario where destructive insulitis is caused by recurrent exposure of specific antigens due to the physiological turnover of beta cells. This sensitization initiates the evolution of reactive clones that remain silent in the regional lymph nodes, where they succeed to evade regulatory clonal deletion.

Animals↗
PubMed2006

The dual role of Fas-ligand as an injury effector and defense strategy in diabetes and islet transplantation.

The exact process that leads to the eruption of autoimmune reactions against beta cells and the evolution of diabetes is not fully understood. Macrophages and T cells may launch an initial immune reaction against the pancreatic islets of Langerhans, provoking inflammation and destructive insulitis. The information on the molecular mechanisms of the emergence of beta cell injury is controversial and points to possibly important roles for the perforin-granzyme, Fas-Fas-ligand (FasL) and tumor-necrosis-factor-mediated apoptotic pathways. FasL has several unique features that make it a potentially ideal immunomodulatory tool. Most important, FasL is selectively toxic to cytotoxic T cells and less harmful to regulatory T cells. This review discusses the intrinsic sensitivity of beta cells to FasL-mediated apoptosis, the conditions that underlie this beta cell sensitivity, and the feasibility of using FasL to arrest autoimmunity and prevent islet allograft rejection. In both the autoimmune and transplant settings, it is imperative to progress from the administration of nonspecific immunosuppressive therapy to the concept of beta-cell-specific immunomodulation. FasL evolves as a prime candidate for antigen-specific immunomodulation.

Animals↗
PubMed2006

Treatment of human bone marrow with recombinant placenta immunoregulator ferritin results in myelopoiesis and T-cell suppression through modulation of the cytokine-chemokine networks.

OBJECTIVE: Placenta immunomodulator ferritin (PLIF) is a cloned human chimeric ferritin H chain with a novel non-ferritin C-terminal 48 amino acid sequence (C48). Recombinant PLIF-C48 exhibited cell-mediated immunosuppression. The aim of the current study was to investigate the regulatory effects of native placental ferritin (PLF), recombinant PLIF, and C48 on hematopoiesis of human bone marrow (BM). METHODS: BM mononuclear cells (BM-MNCs) and CD34(+) selected cells were treated in vitro with either PLF, PLIF, or C48 without and in combination with granulocyte (G)-monocyte (M) colony-stimulating factor (GM-CSF) and subjected to hematopoietic progenitor cell assay. Cytokines and chemokines secreted by the treated cells were evaluated in culture supernatant using antibody array assays to determine mechanism of action. RESULTS: In vitro treatment of BM-MNCs with PLF, PLIF, or C48 induced significant growth of myeloid colonies and when mixed with GM-CSF or Granulocyte-Colony Stimulating Factor (G-CSF) exhibited additive enhanced colony forming units-granulocyte monocyte growth. Yet, C48 treatment of selected CD34(+) cells did not yield colony formation and did not affect their response to GM-CSF. Treatment of BM-MNCs with C48 for 48 hours induced secretion of marked levels of GM-CSF, interleukin (IL)-6, IL-1, and IL-10. These cytokines were secreted primarily by C48-treated BM adherent cells and partly by nonadherent cells, whereas the CD34(+) selected cells secreted IL-6 only. CONCLUSION: C48-PLIF enhancement of myelopoiesis resulted from cross talk between BM accessory cells and progenitor cells. The differential PLIF-C48 effects (i.e., myeloid progenitor cell growth and T-cell suppression) are due to their effect on the cytokine-chemokine networks.

Adjuvants, Immunologic↗
PubMed2006

The tale of early hematopoietic cell seeding in the bone marrow niche.

Since introduction of the notion of a "niche" that hosts engraftment and activity of hematopoietic cells, there is a massive effort to discover its structure and decipher its function. Our understanding of the niche is continuously changing with reinterpretation of traditional concepts and apprehension of new insights into the biology of hematopoietic cell homing, seeding, and engraftment. Here we discuss some of the early events in hematopoietic stem cell seeding and engraftment and propose a perspective based on visualization of labeled bone marrow cells in real time in vivo. Primary seeding of hematopoietic cells in the bone marrow niches evolves as a complex and dynamic process; however, it follows discrete topological and chronological patterns. Initial seeding occurs on the endosteal surface of the marrow, which includes heterogeneous niches for primary seeding. Several days after transplantation the endosteal niches become more restrictive, hosting primarily mitotically quiescent cells, and gradual centripetal migration is accompanied by engagement in proliferation and differentiation. The hematopoietic niches evolve as heterogeneous three-dimensional microenvironments that are continuously changing over time.

Animals↗
PubMed2006

Prolonged course of familial hemophagocytic lymphohistiocytosis.

Familial hemophagocytic lymphohistiocytosis is usually diagnosed in the first 2 years of life and, if untreated, is rapidly fatal. We describe a 10-year-old boy with a 9-year history of prolonged fever and progressive hepatosplenomegaly who was diagnosed as having hemophagocytic lymphohistiocytosis 2, being homozygote to a previously described mutation in the PRF1 gene, and cured by the HLH-2004 protocol and allogenic bone marrow transplantation. This unique case emphasizes the heterogeneity of this disease and the diversity of its clinical presentations.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2006

Novel approaches for the management of patients with Ewing sarcoma.

The concepts of tailored therapy according to genetic profiling and response based on minimal residual disease evaluation during therapy are attracting increasing interest in modern clinical oncology. Children with acute lymphoblastic leukemia are being stratified to various treatment arms with different intensities according to the genetic characteristics of their leukemia and their response to therapy as measured by real-time polymerase chain reaction. Our ability to quickly identify patients with Ewing sarcoma who have a poor prognosis, and to offer them aggressive therapeutic modalities, such as stem cell transplantation, may result in an improved cure rate. Based on the knowledge gained by gene expression profiling and gene silencing techniques we can expect the emergence of new specific drugs that will target malignant cells without causing damage to normal tissue, resulting in improved cancer therapy.

Disease-Free Survival↗
PubMed2006

Catheter-associated bloodstream infections in pediatric hematology-oncology patients: factors associated with catheter removal and recurrence.

The aims of this study were to analyze the factors associated with antibiotic failure leading to tunneled central venous catheter (CVC) removal during catheter-associated bloodstream infections (CABSIs) and with recurrence and reinfection in children with cancer. All cases of CABSI in patients attending the Department of Pediatric Hematology-Oncology between November 2000 and November 2003 were reviewed. A total of 207 episodes of CABSI, including multiple episodes involving the same catheter, were identified in 146 of 410 tunneled CVCs (167 Hickman, 243 implantable ports). The most common organism isolated was coagulase-negative Staphylococcus (CONS). The CVC was removed in 96 (46%) episodes. Hypotension, persistent bacteremia, previous stem cell transplantation, multiple CABSIs in the same CVC, exit-site infection, inappropriate empiric antibiotic therapy, and Candida infection were all significantly associated with increased risk of catheter removal (P < 0.05, odds ratios 7.81, 1.14, 2.22, 1.93, 3.04, 2.04 and 24.53, respectively). There were 12 episodes of recurrent infection, all except 1 caused by CONS (odds ratio 20.5, P = 0.006). Inappropriate empiric therapy, especially in implantable ports, was the only mutable risk factor for antibiotic failure. Because CONS was the predominant isolate in these devices, adding glycopeptides to the empiric therapy for suspected implantable-port CABSI might decrease the removal rate. This issue should be explored in future controlled trials.

Adolescent↗
PubMed2005

Acute lymphoblastic leukemia in a patient with chronic granulomatous disease and a novel mutation in CYBB: first report.

We report for the first time a child with chronic granulomatous disease (CGD) who developed acute lymphoblastic leukemia (ALL). The diagnosis of CGD was made at the age of 4 months, by studies of his neutrophil functions. The superoxide production of the cells was negligible, as was the bactericidal activity. He was found to have a deficiency of the gp91(phox) subunit of the leukocyte NADPH oxidase, with the X-linked inheritance of the disease. DNA analysis revealed a C nucleotide insertion between C1028 and T1029. This insertion has not been described before and causes a frameshift and a premature stop codon at amino-acid position 347. The mother was found to be a carrier of this mutation. At the age of 16 months, the patient developed T-cell ALL. He was treated for 2 years, and today, 10 years since the diagnosis, he is disease-free. During the course of ALL and later, he suffered from recurrent severe pyogenic infections, but careful detection of the etiological agent and promptly instituted specific treatment resulted in his complete recovery. Although primary immune deficiencies have been reported to have an increased tendency to develop malignancies, until now there have been no reports of CGD patients with ALL.

Antineoplastic Agents↗
PubMed2005

Task switching after cerebellar damage.

The authors of this study investigated task switching following cerebellar damage. The study group consisted of 7 children and adolescents (M age=13.8 years) who underwent surgical removal of a benign posterior fossa tumor. They were tested at a sufficient interval after surgery (M lag=6.13 years) for restoration of normal cognitive skills and intelligence. Although all showed normal learning of the task compared with control participants, when rapid behavioral changes were required (short preparation time), they exhibited behavioral rigidity manifested by enhanced switching cost. These results are in line with another study on serial reaction time with the same patients (A. Berger et al., in press). They have important implications for our understanding of the cognitive sequelae of early cerebellar damage as well as the involvement of the cerebellum in task switching.

Adolescent↗
PubMed2005

Pilot study: fluvoxamine treatment for depression and anxiety disorders in children and adolescents with cancer.

OBJECTIVE: To evaluate the safety, tolerability, and benefit of fluvoxamine for the treatment of major depressive disorder or anxiety disorders in children and adolescents with cancer. METHOD: The study was conducted from 2001 to 2004 at a pediatric hematology-oncology center. Fifteen children and adolescents with cancer were treated with fluvoxamine 100 mg/day in an open prospective 8-week trial. Safety and tolerability were evaluated at baseline and at weeks 4 and 8 by blood tests and the Side Effects Checklist. Clinical benefit was assessed with the Clinical Global Impressions-Improvement, the Children's Depression Rating Scale-Revised, and the Pediatric Anxiety Rating Scale. RESULTS: Fluvoxamine was well tolerated by all subjects. Psychiatric symptoms improved significantly. CONCLUSIONS: In this open trial, fluvoxamine appeared to be well tolerated and was associated with a promising reduction in the depression and anxiety symptoms of pediatric patients with cancer.

Adolescent↗
PubMed2005

Clinical and molecular variability in congenital dyserythropoietic anaemia type I.

Congenital dyserythropoietic anaemia (CDA) type I is a rare, inherited disorder characterised by ineffective erythropoiesis and macrocytic anaemia. Complex bone disease has only occasionally been associated with this disease. CDA I is caused by mutations in the CDAN1 gene encoding for codanin-1. Our aim was to characterise the CDAN1 mutation in eight unrelated patients with sporadic CDA I, three of whom had complex bone disease. Six novel mutations in the CDAN1 gene were identified. In two patients, one mutation and in another, both mutations were elusive. No patient was homozygous for a null-type mutation. However, one patient with complex bone disease was homozygous for a splice-site mutation (IVS-12+5G>A). Western blotting revealed that codanin-1 synthesis was 65% less than the control. Five single nucleotide polymorphisms (SNPs) previously unreported in the literature or the SNP database were also identified. Although the absence of codanin-1 is probably lethal, the presence of 35% of the protein was compatible with life but was associated with severe clinical manifestations. However, in most patients studied, no correlation could be established between the expected levels of codanin-1 or the nature of the mutation and the severity of the clinical manifestations.

Adolescent↗
PubMed2005

Serum ferritin level as a predictor of impaired growth and puberty in thalassemia major patients.

OBJECTIVE: Previous studies suggested that in patients with thalassemia major, initiating deferoxamine (DFO) therapy before puberty can prevent iron-induced failure of growth and puberty. However, early initiation of chelation has also been associated with DFO toxicity. The aim of this retrospective study was to determine the prevalence rates of endocrine complications and DFO bone toxicity in our thalassemia major patients and to correlate them with the degree of iron chelation. METHODS: Thirty-nine patients with thalassemia major were followed for a median of 16.3 yr (range 2-28). Individual mean serum ferritin level during the study period was calculated using repeated annual measurements. Bone DFO toxicity was assessed by wrist and spine radiographs; endocrine dysfunction by anthropometric measurements and pubertal stage; and hypogonadotropic hypogonadism by lack of luteinizing hormone response to gonadotropin-releasing hormone. RESULTS: Chelation therapy was initiated at median age 4.9 yr. Mean serum ferritin level during the study period was 2698 +/- 1444 ng/mL. Hypogonadism was noted in 59% of the patients who reached pubertal age, and short stature was found in 36% of patients who reached final height. Mean ferritin level of 2500 ng/mL during puberty was the cut-off for hypogonadism, and ferritin level of 3000 ng/mL during prepuberty was the cut-off for final short stature. None of the patients who attained final height had signs of DFO bone toxicity. CONCLUSIONS: High serum ferritin levels during puberty are a risk factor for hypogonadism, and high serum ferritin levels during the first decade of life predict final short stature. It remains to be determined whether improving chelation by earlier initiation of DFO or by the combined use of DFO and deferiprone will lead to better growth and sexual development without DFO toxicity.

Adolescent↗
PubMed2005

Motor and non-motor sequence learning in children and adolescents with cerebellar damage.

Cerebellar involvement in motor and non-motor sequence learning was examined with serial reaction time tasks (SRT). Our sample consisted of 8 children and adolescents who had undergone surgical removal of a benign posterior fossa tumor (PFT) during childhood. None of them had undergone chemotherapy or cranial radiation therapy (CRT). Ages ranged from 1-11 years at surgery and 9-17 years at testing. The children were tested not earlier than 2.5 years after surgery (M = 5.9 years), enabling brain plasticity and recovery of functions. Their performance was compared with a matched control sample. The PFT group was not impaired in the implicit learning of sequences, as reflected in their performance in blocks with a repeated sequence, both before and after a random block. However, in the perceptual task, their performance deteriorated more than that of the control group when a random block was introduced, suggesting that it was more difficult for the patients to respond flexibly or change their response set when encountering changing task demands. These results are in line with another study by our group on task switching with the same patients.

Adolescent↗