PubMed Health⌕ Search

Biomedical subjects

G Rechavi

Publications and source records attributed to G Rechavi.

At least 73 records · Page 4Linked to original sources
PubMed1998

Role of gamma/delta T cells in a patient with CD4+CD3- lymphocytosis, hypereosinophilia, and high levels of IgE.

BACKGROUND: CD4+CD3- T cells have previously been shown to play a pathogenic role in the hypereosinophilic syndrome by secreting IL-5 and IL-4. OBJECTIVES: The goal of this study was to study the role of CD4+CD3- and other T-cell subsets in a patient with eosinophilia, dermatitis, and a high level of IgE (100,000 IU/mL) in the serum. METHODS: We isolated PBMCs and performed flow cytometry, cell cultures, and in vitro assays of Ig, lymphokine production, and cell-mediated cytotoxicity. RESULTS: Flow cytometric and immunohistochemical analysis of the PBMCs revealed a major population (consisting of approximately 85% of the CD4+ T cells) that lacked expression of CD3 and T-cell receptors on the cell surface (CD4+CD3- T cells), but did express CD3 peptides in the cytoplasm. Activation of the PBMCs in vitro resulted in a 100-fold greater than normal release of IL-4, whereas IFN-gamma production was less than normal, suggesting a predominantly type 2 helper functional phenotype of the CD4+CD3- T cells. Importantly, both CD4-CD8(low) Vdelta1+ T-cell receptor gammadelta+ and CD4+CD3- T cells were cultured from the PBMCs. The former secreted IFN-gamma exclusively, whereas the latter secreted both IL-4 and IFN-gamma. Furthermore, only the T-cell receptor gammadelta+ lymphocytes were cytotoxic to autologous B-lymphoblastoid cells and specifically inhibited IgE production in cultures of autologous polyclonally stimulated PBMCs. CONCLUSIONS: The results suggest that CD8(low) Vdelta1+ T-cell receptor gammadelta+ clones functionally counteract IgE-inducing effects of type 2 CD4+CD3- helper cells in this patient with hypereosinophilic syndrome.

Adult↗
PubMed1998

An identical novel mutation in BRCA1 and a common haplotype in familial ovarian cancer in non-Ashkenazi Jews.

Unique germline mutations in BRCA1 and BRCA2 account for inherited predisposition to breast and ovarian cancer in high-risk families. In Jewish high-risk individuals of Ashkenazi (east European) descent, three predominant mutations, 185delAG and 5382insC (BRCA1) and 6174delT (BRCA2), seem to account for a substantial portion of germline mutations, and two of these mutations (185delAG and 6174delT) are also found at about 1% each in the general Jewish-Ashkenazi population. We identified a novel BRCA1 mutation in two Jewish-non-Ashkenazi families with ovarian cancer: a thymidine to guanidine alteration at position 3053, resulting in substitution of tyrosine at codon 1017 for a stop codon (Tyr1017Ter). The mutation was first detected by protein truncation test (PTT) and confirmed by sequencing and a modified restriction digest assay. Allelotyping of mutation carriers using intragenic BRCA1 markers revealed that the haplotype was identical in these seemingly unrelated families. No mutation carrier was found among 118 unselected Jewish individuals of Iranian origin. Our findings suggest that this novel mutation should be incorporated into the panel of mutations analysed in high-risk families of the appropriate ethnic background, and that the repertoire of BRCA1 mutations in Jewish high-risk families may be limited, regardless of ethnic origin.

Adult↗
PubMed1998

Cone and platelet analyser (CPA): a new test for the prediction of bleeding among thrombocytopenic patients.

The risk of bleeding among thrombocytopenic patients was evaluated using our new cone and platelet analyser (CPA) test. Using this test, adherence of platelets was quantitated on extracellular matrix and expressed as percent of surface coverage (SC) and the average size (AS) of aggregates. 42 thrombocytopenic patients with ITP (n=23), post chemotherapy (n= 12) and others (n= 7) were tested over a total of 82 visits. On each visit, complete blood count and CPA tests were performed and patients were evaluated for evidence of bleeding (found in 40 visits). Bleeding patients had significantly lower platelet counts (27.4 +/- 22.0 v 47.1 +/- 21.0 x 10(9)/l), lower haematocrit values (30.2 +/- 8.1 v 35.2 +/- 6.6%), lower MPV (6.83 +/-1.89 v 8.98 +/- 1.13 fl), and lower SC (4.87 +/- 3.95 v 10.33 +/-5.48%) and AS (33.99 +/- 14.94 v 52.9 +/- 24.34 microm2). Univariate analysis yielded platelet count < or =20.0 x 10(9)/l, MPV < or =8 fl, haematocrit <35%, SC <5%, AS< or =40 microm2 as significantly associated with bleeding, whereas only MPV and SC were associated with bleeding (OR 6.95, CI 2.25-21.46 and OR 4.27, CI 1.29-14.16, respectively) by multivariate analysis. When taken together, 21/22 of patients (95%) with both low SC (<5%) and low MPV (<8.0 fl) had bleeding symptoms, whereas only 9/43 (21%) patients with both these parameters above these values experienced bleeding symptoms. We conclude that the CPA test and the parameter SC (<5%) together with MPV (< or =8 fl) might be used as independent predictors of bleeding in the management of thrombocytopenic patients.

Adolescent↗
PubMed1998

Association between hyperflexibility of the thumb and an unexplained bleeding tendency: is it a rule of thumb?

A bleeding tendency manifested by petechiae and ecchymoses is one of the most common causes for referral of patients to haematology clinics. Vessel wall pathology is not usually considered to be a cause for deranged haemostasis, although coexistence of increased capillary fragility and joint hypermobility have been reported. We determined the frequency of thumb hyperextensibility and scored the findings in a series of 44 patients referred because of ecchymoses and petechiae, as well as 261 control children and their mothers. All 44 patients had normal coagulation studies. Thumb flexibility score was +4 in 30 patients, +3 in eight patients, +2 in five patients and +1 in one of the index patients. In the control group, only one of 261 had a +4, and three had a +3 score, and two of 260 mothers had a +4 score. Ecchymoses were not observed in any of these subjects, nor in the +1 patients. Based on clinical presentation and normal coagulation studies, we suggest that our patients had an underlying subtype of Ehlers-Danlos syndrome. In view of the dramatically high occurrence of thumb hyperextensibility in patients with unexplained mild bleeding tendency, costly haemostatic and coagulation studies on such patients may not be necessary.

Child↗
PubMed1998

Fast-FISH detection and semi-automated image analysis of numerical chromosome aberrations in hematological malignancies.

A new fluorescence in situ hybridization (FISH) technique called Fast-FISH in combination with semi-automated image analysis was applied to detect numerical aberrations of chromosomes 8 and 12 in interphase nuclei of peripheral blood lymphocytes and bone marrow cells from patients with acute myelogenous leukemia (AML) and chronic lymphocytic leukemia (CLL). Commercially available alpha-satellite DNA probes specific for the centromere regions of chromosome 8 and chromosome 12, respectively, were used. After application of the Fast-FISH protocol, and microscopic images of the fluorescence-labelled cell nuclei were recorded by the true color CCD camera Kappa CF 15 MC and evaluated quantitatively by computer analysis on a PC. These results were compared to results obtained from the same type of specimens using the same analysis system but with a standard FISH protocol. In addition, automated spot counting after both FISH techniques was compared to visual spot counting after standard FISH. A total number of about 3,000 cell nuclei was evaluated. For quantitative brightness parameters, a good correlation between standard FISH labelling and Fast-FISH was found. Automated spot counting after Fast-FISH coincided within a few percent to automated and visual spot counting after standard FISH. The examples shown indicate the reliability and reproducibility of Fast-FISH and its potential for automatized interphase cell diagnostics of numerical chromosome aberrations. Since the Fast-FISH technique requires a hybridization time as low as 1/20 of established standard FISH techniques, omitting most of the time consuming working steps in the protocol, it may contribute considerably to clinical diagnostics. This may especially be interesting in cases where an accurate result is required within a few hours.

Aneuploidy↗
PubMed1997

Central nervous system involvement at diagnosis in a case of pediatric CD30+ anaplastic large cell lymphoma.

Central nervous system (CNS) involvement in Ki-1/CD30 lymphoma is extremely rare, in contrast to the frequent involvement in other types of pediatric non-Hodgkin's lymphoma. No mechanism has yet been proposed to explain the sparing of the blood brain barrier in Ki-1/lymphoma. We present a 2-year-old boy who was admitted to the Department of Pediatric Hemato-Oncology due to lethargy, progressive breathing difficulties, massive diffuse lymphadenopathy, hepatosplenomegaly, and ichthyosis-like skin involvement with epidermolysis. A lymph node biopsy was compatible with Ki-1/CD30 anaplastic large cell lymphoma (ALCL). Bone marrow aspirate and biopsy demonstrated reactive hyperplasia. Cytogenetic analysis displayed hyperdiploid cells with 1p(-) in most cells. Cerebrospinal fluid examination showed pleocytosis with CD30+ cells. Possible mechanisms which could enable CNS involvement in this unusual case are discussed.

Central Nervous System Neoplasms↗
PubMed1997

Bilateral femoral stress fractures in a child due to in-line (roller) skating.

We report a child who presented with a limp following 6 weeks of strenuous roller skating. Directed X-rays on admission were normal but a 99mTc-methylene diphosphanate bone scan demonstrated increased uptake in the mid-thirds of the femurs compatible with grade IV stress fracture. Immediate abstention from roller skating for 5 weeks resulted in a complete cure. The "new" side effect of this increasingly popular sport is discussed with regard to paediatric stress fractures and to other roller skating-associated injuries.

Child, Preschool↗
PubMed1997

Ubiquitous expression of a cloned murine thymopoietin cDNA.

Thymopoietin (TP) was originally isolated as a 5-kD 49-aa protein from bovine thymus and was subsequently observed to affect T-cell differentiation and function. We report here the molecular cloning of a murine TP cDNA. The 2,514 bp fragment contains a 630 bp open reading frame that encodes for 210 aa, highly homologous to the first 220 aa of the human TP beta and TP gamma isoforms and to bovine TP. Southern blot analysis of genomic DNA revealed that in mouse, calf and human TP is encoded by a single genomic locus. Recently, it was found that one of the TP isoforms designated TP beta is a homologous protein to the lamina-associated polypeptide 2 (LAP2), which is thought to play an important role in the regulation of nuclear architecture by binding lamin B1 and chromosomes in a manner regulated by phosphorylation during mitosis. In this study we report the TP expression at the transcription level in 17 murine and rat tissues of different origins and 18 lymphoid and nonlymphoid cell lines. The assessment of TP mRNA expression by S1-nuclease protection assays and in situ hybridizations revealed that its expression is not exclusive to thymus, but rather ubiquitous, higher in lymphatic tissues, but also in other cells characterized with a high rate of proliferation. TP was also shown to be expressed in athymic and old animals, lacking a functional thymus gland. Further in situ hybridization studies revealed that within the thymus, the highest levels of TP mRNA are noted at the cortex. These results suggest a possible role for TP in proliferation and cell cycle control.

Amino Acid Sequence↗
PubMed1997

Absence of p53 mutations in malignant mesotheliomas.

Mutations in the p53 gene are the most common genetic alterations found in human malignancies. In this study, a search was done for mutations in the conserved regions of the p53 gene in malignant mesotheliomas. Thirteen malignant mesotheliomas collected over the preceding 12 yr and maintained in paraffin blocks were examined by polymerase chain reaction (PCR) followed by both single-strand conformation polymorphism (SSCP) and denaturing gradient-gel electrophoresis (DGGE). Direct sequence analysis was performed in cases suspected for mutations. No mutations in exons 5 to 8 of the p53 gene were detected. Our results suggest that malignant transformation of human mesothelioma cells does not require inactivation of p53 by point mutations in the conserved regions of the gene.

Adult↗
PubMed1997

Hodgkin's lymphoma in systemic onset juvenile rheumatoid arthritis after treatment with low dose methotrexate.

We describe the occurrence of malignant lymphoma as a possible complication of immunosuppression associated with low dose methotrexate (MTX) therapy for juvenile rheumatoid arthritis (JRA). A 6-year-old girl with systemic onset JRA who had received low dose MTX therapy for 16 months developed diffuse peripheral lymphadenopathy and enlargement of the lymph nodes in the mediastinum, hilum of the lungs, and liver. Lymph node histology disclosed mixed cellularity Hodgkin's lymphoma; the neoplastic cells were positive for CD30 and CD15, but negative for Epstein-Barr virus RNA or EBV latent membrane protein. After chemotherapy, the girl had complete remission of her disease lasting for 18 months; however, the disease relapsed and autologous peripheral stem cell transplantation was performed. Although the occurrence of lymphoma may be associated with autoimmune diseases, our observations suggest that in pediatric patients, the increasing use of low dose MTX therapy for JRA may be an additional factor for the development of lymphoproliferative disease.

Arthritis, Juvenile↗
PubMed1996

Vincristine treatment triggering the expression of asymptomatic Charcot-Marie-Tooth disease.

A 16-year-old male suffering from Ewing's sarcoma of the pelvis was treated with vincristine as part of his chemotherapeutic protocol. The boy was never known to suffer from any neurological problems. His father had a mild limp, attributed to prolonged "taxi driving," that was never investigated medically. The first course of treatment, which included 2 mg of vincristine, resulted in clinical improvement. However, at the same time the patient developed severe weakness of both upper and lower limbs, areflexia, and gradually a pes cavus deformity. Nerve conduction studies were suggestive of severe peripheral sensorimotor neuropathy, axonal and demyelinative. A definite diagnosis of Charcot-Marie-Tooth was confirmed by molecular analysis showing the typical duplication of 1.5 megabases at 17 p11.2. This unique manifestation of vincristine neurotoxicity is reported and discussed.

Adolescent↗
PubMed1996

Minimal residual disease post-bone marrow transplantation for hemato-oncological diseases.

The detection of minimal residual disease (MRD), which is important in cancer treatment, gained special significance in bone marrow transplantation (BMT-) due to the possibility not just to detect but recently also to prevent, treat and reinduce remission in patients that relapsed post-BMT by immunotherapy. The various modern techniques of MRD detection are described including cytogenetics, analysis of restriction fragment length polymorphism, variable number of tandem repeats by Southern Blot or polymerase chain reaction (PCR), microsatellite sequences, PCR amplification products of the Y chromosome or the Amelogenin gene, quantitative PCR and fluorescence in situ hybridization. The role of MRD detection in refinement of indications for BMT, autografting, prediction of relapse, adoptive immunotherapy, mixed chimerism in nonmalignant diseases and in solid organ transplantation is discussed.

Bone Marrow Transplantation↗
PubMed1996

Curable and non-curable malignancies: lessons from paediatric cancer.

The tremendous progress achieved in understanding the molecular basis of cancer, was unfortunately not followed by a mutual improvement in the morbidity and mortality of adult cancer. In contrast, the success rate achieved in paediatric oncology has increased significantly during the past 30 years, and more than two-thirds of the children with cancer can now be cured. p53 has been shown to have a central role on apoptosis in various cells. As apoptosis is a final common pathway for much of our anti cancer therapy, resistance to apoptosis due to a normal activity of p53 is an important mechanism of tumor resistance and treatment failure. Contrary to the findings in most adult tumors, where about 50% of the tumors lack p53 activity, the rate of p53 mutations in childhood cancer is surprisingly low. This may be the key to the much better prognosis of children with cancer. In most adult tumors, multiple genetic events, between five and seven, are usually involved. The oncogenes involved in such tumors usually represent those located upstream of the nuclear transcription factors. In most paediatric tumors, in contrast, the initiating event is the activation of nuclear transcription factors secondary to chromosomal translocations. It can be speculated that multiple events activating various components of the signal transduction machinery are needed for tumorigenesis, and hence the evolution and progression of such tumors is slow. Moreover, if the malignant cell has to accumulate multiple mutations, the chances of crippling the apoptotic mechanism are higher. Genomic instability evidenced by microsatellite variation has been found in colon, pancreas, breast, liver and ovarian adult tumors, and not in paediatric tumors. As multiple somatic mutations are needed for the initiation and progression of the common adult malignancies, inherent genomic instability can dispose to accumulation of multiple mutations. All these molecular interactions are discussed with relevance to the difference between non-curable, mostly adult tumors, and curable, mostly paediatric tumors.

Antineoplastic Agents↗
PubMed1996

In vitro proliferative advantage of bone marrow cells with tetrasomy 8 in Ewing sarcoma.

We describe a case of a 14.5-year-old boy with a clinically aggressive pelvic Ewing sarcoma. The tumor cells showed the presence of a typical t(11;22)(q24;q12) aberration and gains of chromosomes 8, 10, 14, and 21. To determine the size of the trisomy and tetrasomy 8 clones an interphase analysis by fluorescence in situ hybridization with a centromere-specific chromosome 8 probe was performed. Significant quantitative differences between metaphase and interphase data were obtained. It was shown that culturing of bone marrow cells leads to enrichment of tetrasomy 8 population that may be explained by the proliferative advantage of the tetrasomy 8 cells.

Adolescent↗
PubMed1996

Infectious agents and environmental factors in lymphoid malignancies.

A strong association was found to exist between patterns of lymphoid malignancies and socioeconomic status. B-cell lymphomas and T-acute lymphoblastic leukemia are much more prevalent in developing countries where the chances of acquiring infections especially at a younger age are high. B-cell precursor acute lymphatic leukemia, however, are much more prevalent in the Western world. Many infectious agents are associated with lymphatic malignancies. Epstein-Barr virus is involved in African Burkitt's lymphoma, human immunodeficiency virus-related Burkitt's lymphoma, lymphoproliferative syndrome post-transplantation, and Hodgkin's disease. Other infectious agents which may play a role in lymphoproliferative disorders are human immunodeficiency virus in acquired immune deficiency syndrome-associated lymphoma, human T-lymphotropic virus in adult T-cell lymphoma, Helicobacter pylori in mucosa-associated lymphoid tissue lymphoma, theileriosis in lymphoproliferative syndrome in cattle, Avian leukosis virus in chicken bursal lymphoma, and possibly a bacterial infection in immunoproliferative small intestine disease, potentially reversed by antibiotic therapy. The association between infectious agents and hematologic malignancies may be explained by the creation of large populations of activated cells followed by higher occurrences of 'genetic accidents'. This theory may be reinforced in at least some malignancies with the existence of viral proteins which either have complex relationships with key cellular gene products like p53 and Rb which have roles in cell cycle control, or share common motifs with bc1-2, therefore operating as anti-apoptotic elements. Whenever these genes are deranged, cell deoxysibonucleic acid repair or apoptosis are no longer possible, thereby creating a state of genome instability, increased acquisition of mistakes, and increased chances for malignant transformation.

Animals↗