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Biomedical subjects

A Bagg

Publications and source records attributed to A Bagg.

At least 37 records · Page 2Linked to original sources
PubMed1995

Polymerase chain reaction versus Southern blot hybridization. Detection of immunoglobulin heavy-chain gene rearrangements.

To determine efficiently the clonality of B-cell lymphoproliferative disorders, we modified an immunoglobulin heavy-chain (IGH) gene rearrangement polymerase chain reaction (PCR) assay that requires only a single primer germline variable (VH) and joining (JH) pair and does not involve nested priming, blot hybridization, radioactivity, or sequencing of the amplified PCR product. This simple PCR technique enabled detection of IGH gene rearrangements in as little as 10 pg (one cell equivalent) of DNA or when the clonal-to-polyclonal B-cell ratio was experimentally set at 1:1000. We detected IGH gene rearrangements in 83.5% (71 of 85) of clonal B-cell processes, a sensitivity approaching that of more cumbersome multiple primer and nested primer assays. Moreover, this technique is equally effective with fixed tissues, either B5 or formalin, and can be performed on minute samples, histologic sections, fine-needle aspirates, or cerebrospinal fluids. When compared with conventional Southern blot analysis using a genomic JH probe, the PCR assay demonstrated IGH gene rearrangements in 82% (37 of 45) of B-cell processes positive by Southern blot. No false-positive results were observed in 29 negative control tissues. We now use IGH gene PCR routinely in our laboratory for the detection of clonal B-cells in virtually any tissue sample as an aid in early diagnosis, staging, and monitoring, and the Southern blot procedure is reserved for only a minority of diagnostic cases. for only a minority of diagnostic cases.

B-Lymphocytes↗
PubMed1994

Interleukin-2 activation of human bone marrow in long-term cultures: an effective strategy for purging and generation of anti-tumor cytotoxic effectors.

Our previous studies have shown that IL-2 activated bone marrow cells develop potent tumoricidal activity in vitro and in vivo. With the dual aim of in vitro purging and generation of effectors which could mediate graft-versus-leukemia effects in vivo, IL-2 activation of human bone marrow in long-term cultures (LTC) was tested. Marked cytotoxicity was seen against A375 (melanoma), K562 (CML) and Daudi (lymphoma) cell lines in IL-2 (1000 U/ml) stimulated cultures. Hematopoietic progenitor cell number in these cultures was assessed by day 14 clonogenic assays. In 1-week-old IL-2 stimulated cultures a higher number of clonogenic cells was seen than control LTCs without IL-2. However, thereafter accelerated decrease in the number of clonogenic cells was seen in IL-2 cultures. In vitro purging efficacy was tested by elimination of A375 and K562 cells mixed with normal marrow at 1:10 and 1:100 ratios and co-cultured for 10 days. In IL-2 stimulated cultures, A375 cells capable of proliferation were not detectable at both mixing ratios. K562 elimination was complete only at 1:100 ratio. After 10 days in culture, no Ph1-positive metaphases were seen in IL-2 stimulated BM cultures of 4 patients with CML. These results indicate that IL-2 activation of BM in 1-2 week cultures can lead to generation of marked anti-tumor cytotoxicity and effective in vitro purging in a variety of tumor types.

Bone Marrow↗
PubMed1993

Single-cell analysis of Hodgkin and Reed-Sternberg cells: molecular heterogeneity of gene expression and p53 mutations.

We have used a single-cell based polymerase chain reaction (PCR) amplification technique to examine the gene expression pattern in single Hodgkin's and Reed-Sternberg (H&RS) cells from seven patients with Hodgkin's disease. Single cells were isolated from lymph nodes obtained at diagnosis (5 of 7 patients) or in first or second relapse (2 of 7 patients). Gene expression was examined by hybridization to a panel of 22 cDNA probes. Forty-nine H&RS cells (and 23 CD3+ or CD20+ lymphocytes as controls) from four patients with nodular sclerosing Hodgkin's disease (HD) and one patient each with lymphocyte predominant and mixed-cellularity HD were successfully analyzed by PCR. This analysis provides evidence that single H&RS cells can coexpress genes characteristic of several hematopoietic lineages (monocytes and lymphocytes). Genes characteristic of activated lymphoid cells are expressed in most H&RS cells. Heterogeneity of expression for certain genes between different cases was found and may eventually define molecular subgroups of HD. These findings indicate that H&RS cells of HD resemble activated hematopoietic cells. Phenotypically similar cells from different cases exhibit characteristic molecular differences. In one patient, 5 of 7 single RS cells showed identical p53 cDNA mutations at codon 246 on specific reverse transcriptase [RT]-PCR and sequencing of exons 5 through 8. The novel experimental approach may provide a valuable tool for understanding the molecular events in newly diagnosed Hodgkin's disease and progression of the disease.

Adolescent↗
PubMed1990

Light chain restriction analysis of bone marrow plasma cells in patients with MGUS or 'solitary' plasmacytoma: diagnostic value and correlation with clinical course.

Twenty-eight patients with a diagnosis of 'solitary' plasmacytoma or with gammopathy but with nondiagnostic morphologic examination of the bone marrow were investigated using a short-term bone marrow culture technique which enriched for the plasma cell fraction. The percentage of monotypic plasma cells in these plasma cell enriched cultures was correlated with the subsequent clinical course. The majority of patients with plasmacytoma and a significant number of those with gammopathy but with otherwise non-diagnostic investigations were found to have a monoclonal plasma cell component of greater than 20%. There was a significant correlation between the percentage of monoclonal plasma cells as detected by bone marrow culture and subsequent progression to disseminated myeloma. These results indicate that early bone marrow involvement can be detected by means of plasma cell culture prior to morphologic identification of marrow plasmacytosis and that short-term plasma cell culture distinguishes patients with early, low bulk myeloma from those with monoclonal gammopathy of uncertain significance (MGUS).

Bone Marrow↗
PubMed1989

Clinical relevance of immunophenotypic and immunogenotypic analysis in acute non-lymphoblastic leukaemia.

Molecular biology is playing an increasing role in defining pathology today, and has clinical relevance in the routine work-up of patients with malignant diseases, especially those of the blood and lymphatic system. The majority of acute non-lymphoblastic leukaemias (ANLL) express specific myeloid differentiation markers and are terminal deoxynucleotidyl transferase (Tdt) negative. Rarely, some cases are Tdt+ and express the T-cell marker CD7. Although uncommon in Tdt-ANLL, there appears to be a significant incidence of T-cell receptor beta chain (TCR beta) and/or immunoglobulin heavy chain (IgH) gene rearrangements in Tdt+ ANLLs. We have investigated the immunogenotype of 39 patients with ANLL, including 28 from whom immunophenotypic data were available. Thirty-seven of 39 cases had germline IgH and TCR beta genes. Two cases, one with a myeloid/CD7+ CD2+ immunophenotype, had non-germline IgH gene arrangements detectable on Hind III digests only. The possibility of Hind III polymorphisms, or of true somatic gene rearrangement of the IgH gene in these patients, is discussed. Two additional cases had a Tdt+ CD7+ immunophenotype with germline IgH and TCR beta chain genes. Our results confirm the infrequent occurrence of IgH and TCR beta gene rearrangements in ANLL. Expression of Tdt and/or CD7, often in association with IgH gene rearrangements, would appear to identify a subgroup of ANLL patients that respond poorly to standard ANLL therapy and have a poorer prognosis. The diagnostic and prognostic importance of multiparametric analysis in ANLL is emphasised.

Adolescent↗
PubMed1989

Precursor T-cell lymphoma associated with human immunodeficiency virus type 1 (HIV-1) infection. First reported case.

The majority of lymphomas that develop in human immunodeficiency virus type 1 (HIV-1) positive patients have a B-cell phenotype, with few reported cases of T-cell lymphoma. Within the latter group, those that have been comprehensively phenotyped had a mature helper T-cell phenotype (CD4+). We report, for the first time, an HIV-1 positive patient with a precursor T-cell lymphoma (CD7+,CD1-,CD3-,CD4-, and CD8-). T-cell receptor beta and gamma genes were in the germline configuration and integration of HIV-1 DNA could not be detected in the lymphoma cell genome.

Acquired Immunodeficiency Syndrome↗
PubMed1989

The routine diagnostic utility of immunoglobulin and T-cell receptor gene rearrangements in lymphoproliferative disorders.

Immunophenotypic studies have a well-documented role in the assignment of lineage in the lymphoproliferative disorders. With the exception of mature B-cell disorders, it is difficult to demonstrate clonality by immunophenotypic studies. The advent of specific DNA probes for immunoglobulin and T-cell receptor genes has greatly facilitated the detection of clonality and, to a lesser degree, lineage, in these cases. The authors have evaluated the diagnostic utility of these probes and compared them with standard immunophenotyping in 65 patients with a variety of lymphoproliferative disorders. Their results show a significant correlation (P less than 0.01) between lineage assignment as determined by phenotyping and gene rearrangement studies, with the latter far superior in determining clonality. Furthermore, analysis of gene rearrangements facilitated the documentation of lineage and/or clonality in six cases in which standard techniques had failed. Although the scientific basis of the study of gene rearrangements has been well established, the authors wish to emphasize the role that these techniques have in evaluating problem cases in the routine diagnostic laboratory.

DNA Probes↗
PubMed1989

Circulating monotypic B-cells in multiple myeloma: association with lambda paraproteins.

The peripheral blood and bone marrow mononuclear cell immunophenotype was investigated in series of 41 patients with plasma cell dyscrasias (29 with multiple myeloma and 12 with monoclonal gammopathy of undetermined significance (MGUS) or solitary plasmacytoma). A statistically significant relationship between the presence of monotypic B-cells (MBC) in the peripheral blood and the paraprotein light chain isotype was found in the myeloma patients (P = 0.0025). MBCs were documented in 71% of patients with lambda paraproteins, compared with only 13% of patients with kappa paraproteins. The difference in MBC was independent of disease stage as well as of individual prognosticators such as haemoglobin, renal function, paraprotein size and beta-2-microglobulin, although lambda producers had significantly higher calcium levels than patients with kappa paraproteins (P = 0.03). A similar trend was also noted for MBC to be found more commonly in patients with lambda producing MGUS and solitary plasmacytoma. This phenomenon may account for the worse prognosis in patients with lambda paraproteins. In our hands, immunophenotypic detection of peripheral blood involvement in plasma cell dyscrasias is more sensitive than investigation of karyotype or immunoglobulin gene rearrangements.

B-Lymphocytes↗
PubMed1987

Ferric uptake regulation protein acts as a repressor, employing iron (II) as a cofactor to bind the operator of an iron transport operon in Escherichia coli.

The Fur (ferric uptake regulation) protein is a negative regulator of the aerobactin operon and of several other siderophore-mediated, high-affinity iron transport systems in Escherichia coli. The purified Fur protein and a plasmid containing a lacZ fusion to the aerobactin operon were used in conjunction with an in vitro coupled transcription/translation system to demonstrate that the Fur protein requires Fe(II) or certain other divalent metals as a cofactor to negatively regulate expression of the aerobactin operon. In a second set of experiments, using a restriction site protection assay, Fur was shown to bind to and block the aerobactin promoter in a metal-dependent fashion. It is concluded that Fur acts as a classical negative repressor that, under in vivo conditions, uses ionic Fe(II) as a corepressor. Our results support the hypothesis [Williams, R.J.P. (1982) FEBS Lett. 140, 3-10] that prokaryotic cells may contain a standing pool of free or loosely bound Fe(II) that is capable of acting in a regulatory capacity.

Bacterial Proteins↗
PubMed1986

Chromosome 3q21 abnormalities associated with hyperactive thrombopoiesis in acute blastic transformation of chronic myeloid leukemia.

Two patients with acute blastic transformation of chronic myeloid leukemia (CML) associated with strikingly elevated platelet counts showed abnormalities of chromosome 3q in addition to the standard Philadelphia (Ph1) chromosome translocation. The first patient had an inversion of chromosome 3 (q21q26) cytologically identical to an inversion 3 previously reported in de novo acute megakaryoblastic leukemia, and the second patient showed a translocation between chromosome 3q and the chromosome 9 homologue not involved in the Ph1 translocation, [t(3;9)(q21;q34)]. Previous studies had incriminated either 3q21 or 3q26 as the locus for a regulatory thrombopoietic gene, but the current study suggests that 3q21 is the relevant site.

Adult↗
PubMed1985

The effect of an advanced cardiac life support course on advanced cardiac life support ability.

Thousands of health care providers spend time, money, and energy each year taking the AHA-sponsored ACLS courses, and ACLS-certified health care providers are frequently given greater job responsibility than other health care providers in the same setting. The purpose of this study was to determine the effect of an ACLS course on the ability of health care providers to perform ACLS in a simulated situation. A nonequivalent control group design was used. The sample consisted of 76 health care providers whose job responsibilities included ACLS. The Mega-Code skill station from the ACLS course was used to evaluate ACLS performance. Chi-square analyses showed a significant (p less than 0.05) difference in the posttest pass/fail results of the two groups and a significant (p less than 0.05) difference in the changes from pretest to posttest of the two groups. The research hypotheses were supported, and the researches concluded that the course had a positive effect on the subjects' ACLS ability.

Clinical Competence↗