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R Wasserman

Publications and source records attributed to R Wasserman.

31 records · Page 2Linked to original sources
PubMed1992

The pattern of joining (JH) gene usage in the human IgH chain is established predominantly at the B precursor cell stage.

Preferential utilization of JH and D genes has been demonstrated in the rearranged IgH chain in human peripheral B cells. We report here that the same hierarchy of JH gene usage is observed in leukemic cells arrested in the B precursor stage of differentiation. Specifically, JH4 and JH6 accounted for 42.9% and 35.7%, respectively, of the JH gene usage in the leukemias compared with an expected frequency of 16.7% assuming unbiased gene usage. Within the D gene families, the DN1 gene appears to be overutilized in both populations, representing about 15% of the total gene usage compared with an expected frequency of 3.2%. Because 21 of the 36 leukemias contained only nonproductive IgH rearrangements, the preferential gene usage could not have arisen from pre-B cells that have undergone clonal selection after a productive rearrangement but before surface Ig expression. Nonproductive rearrangements exhibited the biased gene usage seen for productive rearrangements. These findings suggest that a recombination bias favoring certain segments may be the actual mechanism responsible for the apparent preferential utilization of JH and D genes.

Adolescent↗
PubMed1992

VH gene rearrangement events can modify the immunoglobulin heavy chain during progression of B-lineage acute lymphoblastic leukemia.

The presence of multiple VHDJH joinings in upwards of 30% of acute lymphoblastic leukemias (ALL) suggests a relative instability of the rearranged immunoglobulin heavy chain (IgH) gene, but the mechanisms involved are not completely understood. An investigation of the structure of the VHDJH joinings using complementarity determining region (CDR)3 polymerase chain reaction (PCR) in 12 leukemias at both diagnosis and relapse indicates that this instability may increase as a function of time. In only one of seven cases in which relapse occurred within 3 years from diagnosis was a new VHDJH joining identified and this coexisted with the original diagnostic joining. Most strikingly, new VHDJH joinings were identified in four of five cases in which relapse occurred more than 5 years from diagnosis. In this latter population, the instability of the joinings was generated from VH----VH gene replacement events in two cases, since the new joinings retained the original DJH sequences and partial N region homology at the VHD junction, and probably in a third case from a VH gene rearrangement to a common DJH precursor. Furthermore, in five of 23 (21.7%) additional cases studied at diagnosis, subclones were identified that had similar modifications of the VH-N region. These data indicate that VH gene replacement events and VH gene rearrangements to a common DJH joining contribute to the instability of the VHDJH joining in ALL. This phenomenon should be taken into consideration in those methodologies that exploit IgH rearrangements for detection of minimal residual disease.

Adolescent↗
PubMed1992

Residual disease at the end of induction therapy as a predictor of relapse during therapy in childhood B-lineage acute lymphoblastic leukemia.

PURPOSE: More than 95% of children with B-lineage acute lymphoblastic leukemia (ALL) achieve a clinical remission after the induction phase of chemotherapy (first 28 days) as evaluated by morphologic criteria. However, relapse occurs in approximately 30% of these children. The objective of this study was to determine whether the outcome of patients in clinical remission at the end of induction therapy could be predicted using a highly sensitive method to detect residual disease. PATIENTS AND METHODS: All children diagnosed with B-lineage ALL at the Children's Hospital of Philadelphia during a 2-year period were eligible. The extent of residual leukemia was quantitated in remission marrow samples obtained at the end of induction therapy in 44 children using a phage clonogenic assay in association with complementarity-determining-region 3 (CDR3)-polymerase chain reaction (PCR). RESULTS: Residual disease was a significant predictor of outcome independent of WBC count, age, or sex. The estimated relapse-free survival (RFS) during therapy was 50.4% (+/- 12.6%) for patients with high residual disease (> or = 0.6% leukemia cells among total marrow B cells) versus 91.9% (+/- 5.5%) for those with lower levels (P < .002). There were no significant differences in off-treatment RFS between patients with high or low residual disease who completed therapy in continuous remission (P = .82). The overall estimated RFS was 32.3% (+/- 11.6%) for patients with high residual disease versus 62.6% (+/- 10.7%) for patients with lower levels of residual leukemia cells, with a median follow-up of 5.3 years for patients in continuous remission (P < .008). CONCLUSION: PCR detection of high residual disease at the end of induction therapy identifies patients at increased risk for relapse during therapy.

Adolescent↗
PubMed1991

Preferential utilization of specific immunoglobulin heavy chain diversity and joining segments in adult human peripheral blood B lymphocytes.

We have examined at the molecular level the CDR3 and adjacent regions in peripheral blood B lymphocytes of normal individuals. A total of 111 sequences (12-28 sequences from six individuals) were obtained after cloning of the polymerase chain reaction-amplified segments into plasmids or phage. The average length of the VDJ joining was 109 nucleotides, with a range from 79 to 151. Approximately 75% of the sequences were in frame when translated into amino acids. Among the JH segments, JH4 was found most frequently (in 52.5% of the sequences), and JH1 and JH2 segments the least frequently (approximately 1% of the clones). A polymorphic JH6 gene with a one-codon deletion accompanied by a base change was present in two of six patients. Preferential breakpoints were found for JH2, JH3, JH4, and JH5, although the breakpoints of JH6 were distributed more heterogenously. In approximately 90% of the cases, significant homology of the D regions with published D sequences was found. Preferential usage of a particular coding frame was observed in in-frame sequences utilizing DA, D21/9, and DM1 segments. However, in general, all coding frames of germline D genes were used to generate CDR3s. Eight sequences that have a DN1-like D sequence with two base changes at the same positions were identified, suggesting the likely existence of a new germ line D gene belonging to the DN families. Using probes specific for a particular CDR3, the frequency of a specific B cell clone in the peripheral blood of normal individuals was estimated to be at most as high as 1/20,000.

Amino Acid Sequence↗
PubMed1990

Minimal residual disease in childhood B-lineage lymphoblastic leukemia. Persistence of leukemic cells during the first 18 months of treatment.

BACKGROUND: Whether patients in clinical remission for acute lymphoblastic leukemia (ALL) continue to harbor leukemic cells is not known, because methods of detecting residual malignant cells have not been sufficiently sensitive. This information might be useful for predicting recurrence and determining the duration of therapy. METHODS: Using a sensitive new method--identifying complementarity-determining region III sequences with the polymerase chain reaction--we estimated the number of residual leukemic cells in the bone marrow of eight children with B-lineage lymphoblastic leukemia before and after remission. RESULTS: Induction chemotherapy produced a 3-to-4-log reduction in the number of leukemic cells. In all samples obtained up to 18 months after diagnosis, however, 0.004 to 2.6 percent of bone marrow nucleated cells were residual leukemic cells. Among the four patients studied more than 18 months after diagnosis, three had no detectable leukemic cells in marrow samples. Despite this, one of them, who was no longer receiving therapy, had a central nervous system relapse. In one patient receiving maintenance chemotherapy, there was a 60-fold increase in leukemic cells three months before bone marrow relapse. CONCLUSIONS: The complete disappearance of leukemic cells (or their reduction below our method's threshold of detection, 1 in 100,000 cells) may be necessary to achieve a cure of ALL. The quantification of residual leukemic cells in serial marrow aspirates during therapy may allow the early detection of relapse.

Adolescent↗
PubMed1988

Viral infections in pediatric bone marrow transplant patients.

The records of 96 pediatric patients with aplastic anemia or a malignancy who underwent bone marrow transplantation between 1979 and 1986 at The Children's Hospital of Philadelphia were reviewed for laboratory evidence of viral infections. The most common viral diseases identified were herpes simplex virus (HSV), cytomegalovirus and adenoviruses, which were found in 19 (20%), 17 (18) and 17 (18) patients, respectively. HSV was more common in patients with than without graft vs. host disease (GVHD) (9 of 30; 30% vs. 10 of 66; 15%), but the difference did not reach statistical significance. Late or prolonged isolation of HSV occurred in patients with chronic GVHD. Cytomegalovirus was significantly more common in patients with than without GVHD (10 of 30; 33% vs. 7 of 66; 11%). The presence of pretransplant antibody to cytomegalovirus or HSV was a good predictor of subsequent infection. Adenoviruses were isolated from all 3 patients with Burkitt's lymphoma. Adenovirus type 12, a serotype uncommon in man and known to be highly tumorigenic in young hamsters, was recovered from 4 patients. Adenoviruses were not notably more common in patients with GVHD (6 of 30; 20% vs. 11 of 66; 17%). Other viral infections demonstrated included 5 parainfluenza, 4 enteroviruses, 3 human immunodeficiency virus, 1 respiratory syncytial virus, 1 influenza B and 1 rhinovirus.

Adenovirus Infections, Human↗
PubMedDate not supplied

Biomedical imaging modalities: a tutorial.

The introduction of advanced imaging technologies has improved significantly the quality of medical care available to patients. Non-invasive imaging modalities allow a physician to make increasingly accurate diagnoses and render precise and measured modes of treatment. Current uses of imaging technologies include laboratory medicine, surgery, radiation therapy, nuclear medicine, and diagnostic radiology. This paper provides an overview of most of the popular imaging modalities currently in clinical use. It is hoped that a general understanding of the modality from which an image is derived will help researchers in the subsequent analysis of the image data.

Angiography, Digital Subtraction↗