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Biomedical subjects

R A Larson

Publications and source records attributed to R A Larson.

At least 19 recordsLinked to original sources
PubMed1992

Clinical significance of the BCR-ABL fusion gene in adult acute lymphoblastic leukemia: a Cancer and Leukemia Group B Study (8762).

The Philadelphia (Ph1) chromosome, or its molecular counterpart, the BCR-ABL fusion gene, is a rare but important prognostic indicator in childhood acute lymphoblastic leukemia (ALL), but its impact on adult ALL has not been well ascertained. A prospective study of the BCR-ABL fusion gene was begun on patients entered on clinical trials conducted by the Cancer and Leukemia Group B (CALGB). All patients received intensive, multiagent chemotherapy that included daunorubicin. Over 2 years, 56 patients were studied for molecular evidence of a BCR-ABL gene using Southern blot and pulsed-field gel hybridization analysis. Results were compared with cytogenetic detection of a Ph1 chromosome, and clinical features were compared for the BCR-ABL-positive and -negative groups. Molecular methods detected the BCR-ABL gene in 30% of cases compared with cytogenetic detection of the Ph1 chromosome in only 23%. The majority of cases (76%) showed the p190 gene subtype similar to pediatric ALL; the BCR-ABL-positive cases displayed a more homogeneous immunophenotype than the BCR-ABL-negative cases and were predominantly CALLA positive (86%) and B-cell surface antigen positive (82%). The rate of achieving complete remission was similar in the BCR-ABL-positive and -negative groups (71% and 77%, respectively, P = .72). There were more early relapses in the BCR-ABL-positive group, resulting in a shorter remission duration that was especially marked in the CALLA-positive and B-cell antigen-positive populations. These preliminary data suggest that the impact of the BCR-ABL gene on clinical outcome in ALL may be on maintenance of complete remission (CR) rather than achievement of CR when aggressive, multiagent chemotherapy is used. This study identifies the BCR-ABL gene as an important factor in adult ALL and demonstrates the utility of molecular methods for its accurate diagnosis.

Adolescent↗
PubMed1992

Clinical, morphologic, and cytogenetic characteristics of 26 patients with acute erythroblastic leukemia.

We have performed a retrospective analysis of the clinical, morphologic, and cytogenetic findings in 26 patients diagnosed between January 1969 and September 1991 with acute erythroblastic leukemia de novo (EL or AML-M6). Clonal chromosomal abnormalities were found in 20 (77%) patients (95% confidence interval [CI], 61% to 93%). Loss of all or part of the long arm (q) of chromosomes 5 and/or 7 was observed in 17 (65%) patients (95% CI, 47% to 83%). In addition, the karyotypes were often complex, with multiple abnormalities and subclones. Among the remaining nine patients, six had a normal karyotype and one each had trisomy 8, t(3;3), or t(3;5). The overall frequency of abnormalities of chromosomes 5 and/or 7 observed in our M6 patients is similar to that observed in our patients with therapy-related acute myeloid leukemia (t-AML; 99 of 129 patients, 77%), but substantially higher than that noted in our other patients with AML de novo (French-American-British [FAB] subtypes M1-M5: 52 of 334 patients, 16%). Our M6 patients with abnormalities of chromosomes 5 and/or 7 were older and had a shorter median survival (16 v 77 weeks [P = .005]) than did the M6 patients without these abnormalities. We found no correlation between morphologic features and either cytogenetic abnormalities or clinical outcome. Of note was the finding that the percentage of myeloblasts, which may account for only a small fraction of the total marrow elements when the revised FAB criteria are applied, had no bearing on prognosis. We conclude that acute erythroblastic leukemia, when defined by morphologic criteria, consists of two distinctive subgroups: one group tends to be older, has complex cytogenetic abnormalities, especially of chromosomes 5 and/or 7, and shares biologic and clinical features with t-AML; the other group, with simple or no detectable cytogenetic abnormalities, has a more favorable prognosis when treated with intensive chemotherapy.

Adolescent↗
PubMed1992

Clinical and cytogenetic responses to granulocyte-macrophage colony-stimulating factor in therapy-related myelodysplasia.

We treated 10 patients with a therapy-related myelodysplastic syndrome with escalating doses of granulocyte-macrophage colony-stimulating factor (GM-CSF; sargramostim) in a phase II trial and used sequential cytogenetic analyses to determine whether there was stimulation of nonclonal hematopoiesis. The GM-CSF was administered by continuous intravenous infusion over 2 hours daily for 14 days, followed by a 14-day rest period. The initial starting dose was 60 micrograms/m2/d. The GM-CSF dose was escalated within individual patients to 125 micrograms/m2, 250 micrograms/m2, and then 500 micrograms/m2/d until the peripheral blood neutrophil count at least doubled and exceeded 1,000/microL. GM-CSF treatment then continued in monthly maintenance cycles. During 57 treatment courses, the neutrophil count increased in 52 but only doubled and exceeded 1,000/microL in 21. Mild eosinophilia was stimulated in five patients, but only two had greater than 1,000 eosinophils/microL. In only three patients was any stimulation of platelet or red blood cell production observed, and thus, little change in transfusion requirements occurred. The bone marrow karyotypes from individual patients either remained completely abnormal or became increasingly abnormal over the course of treatment. We found no evidence that GM-CSF preferentially stimulated normal marrow stem cells to proliferate or had the ability to eradicate the cytogenetically abnormal clone by inducing terminal differentiation. Although the effect on granulopoiesis was transient and dependent on continued GM-CSF treatment, the increase in the neutrophil count was clinically important in some patients, allowing more effective control of ongoing infections.

Adolescent↗
PubMed1992

Alteration of the proliferative rate of acute myelogenous leukemia cells in vivo in patients.

Ten patients with active acute myelogenous leukemia (AML) received either 13 cis retinoic acid (RA) + alpha interferon (IFN) or recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) for 3 days. Cell cycle measurements were performed before and at the conclusion of administration of the bioactive agent(s). The proliferative rate of the leukemia cells in vivo decreased in four of five patients receiving RA+IFN whereas in one patient proliferation accelerated. The proliferative rate of AML cells accelerated in three of the five patients who received rhGM-CSF and slowed in two patients. These data show that while the proliferative rate of AML cells can be altered in vivo, the effect produced by bioactive agents may be the opposite of the desired effect. Furthermore, the studies described here demonstrate the usefulness of marrow biopsies for measuring the percent S-phase cells and the importance of measuring the duration of S phase so that the effects of bioactive agents on the cell cycle time of the leukemia cells can be determined.

Biopsy↗
PubMed1992

Ferric-ion-photosensitized damage to DNA by hydroxyl and non-hydroxyl radical mechanisms.

Iron(III) and UVA (320-400 nm) light strongly diminished the transforming activity of Haemophilus influenzae DNA in the presence of oxygen. Iron(III) alone in the absence of light had no measurable effect on the transforming activity. The chelating agent ethylenediaminetetraacetic acid (EDTA) conferred virtually complete protection, but hydroxyl radical scavengers (mannitol, methanol, ethanol, isopropanol and dimethyl sulfoxide) inhibited only a small fraction of the inactivation. Treatment of plasmid DNA (pBR322) with iron(III) results in the conversion of the covalently closed circular form of the plasmid to open circles and ultimately to the linear form. Concomitant with the alteration in the conformation of the plasmid, the ability to transform Escherichia coli was reduced. In model systems, iron(III) photoreacted with the DNA backbone causing nicking and double-strand breakage. The results are consistent with a mechanism involving a preliminary complexation of iron(III) by DNA followed by the generation of reactive free radicals other than .OH. We suggest that bound iron, or other UV-absorbing transition metal complexes, may be chromophores capable of causing DNA damage in the long-wave near-UV region.

DNA Damage↗
PubMed1992

Detection of trisomy 12 in chronic lymphocytic leukemia by fluorescence in situ hybridization to interphase cells: a simple and sensitive method.

Trisomy 12 is the most common cytogenetic abnormality in chronic lymphocytic leukemia (CLL), and a number of studies have suggested that it may be an adverse prognostic indicator. We have evaluated the usefulness of fluorescence in situ hybridization with a chromosome 12-specific probe as a simple means for detecting trisomy 12 in interphase cells. Forty cases of B-cell CLL previously studied with conventional cytogenetic techniques were analyzed with a biotinylated probe to the centromeric region of chromosome 12. Thirty of these retrospective cases could be reevaluated with in situ hybridization. Our analysis showed three hybridization signals (ie, trisomy 12) in interphase cells from seven of seven cases found previously to have trisomy 12. Trisomy 12 was also detected in five additional cases: in one case thought to have a normal karyotype, in two cases that had been inadequate for routine cytogenetic analysis, and in two cases that had been found to have an abnormal karyotype without trisomy 12. In a prospective series of 20 newly accrued CLL cases, all cases were analyzed successfully by in situ hybridization and six (30%) showed trisomy 12. We were able to perform the analysis on routinely prepared and previously Wright-stained peripheral blood smears. We conclude that fluorescence in situ hybridization is a simple means for the detection of trisomy 12 in CLL. The technique is more sensitive than conventional cytogenetic analysis and would be a useful tool in clinical studies.

Chromosomes, Human, Pair 12↗
PubMed1992

Chromosomal loss and deletion are the most common mechanisms for loss of heterozygosity from chromosomes 5 and 7 in malignant myeloid disorders.

We have examined a population of patients with acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS) for loss of heterozygosity of polymorphic markers on chromosomes 5 and 7. The rationale for this study was the observation that the majority of patients with therapy-related leukemia (t-AML or t-MDS), resulting from cytotoxic treatment for prior malignancies, have loss of chromosome 5 and/or 7 or deletions involving the long arms of one or both of these chromosomes. This cytogenetic finding suggested that tumor-suppressor genes, important in the development of AML, may be located in these chromosomal regions. We analyzed a total of 60 patients, 43 with primary MDS/AML de novo and 17 with t-MDS/t-AML. Leukemia cells were evaluated for restriction fragment length polymorphisms (RFLPs). Leukemia cell genotypes were compared with lymphoblastoid cell genotypes from the same patients. Two cases of loss of heterozygosity were identified from chromosomes lacking visible deletions: one involving chromosome 5 in a patient with AML de novo who had a visible deletion of 5q at a later stage of the disease, and one involving chromosome 7 in a patient with t-AML. We conclude that allele loss from loci on chromosomes 5 and 7 in MDS/AML, when it occurs, usually results from major deletion or simple chromosome loss, rather than from mitotic recombination or chromosome loss with duplication of the remaining homologue.

Base Sequence↗
PubMed1992

The selective use of AMSA following high-dose cytarabine in patients with acute myeloid leukaemia in relapse: a Leukemia Intergroup study.

This clinical trial was designed to evaluate the role of high-dose cytarabine (ara-C) in the treatment of adults with acute myeloid leukaemia (AML) in first relapse. We also tested the hypothesis that the selective use of AMSA (100 mg/m2/d on days 7, 8 and 9) would increase the complete remission (CR) rate when leukaemia cells remained in the bone marrow immediately following 6 d of Ara-C (2-3 g/m2/12 h) alone. Of 155 patients evaluable for response, 115 (74%) experienced marked cytoreduction by day 6 and received no further induction chemotherapy; 53 (45%) of these patients achieved CR after one course and 45 (38%) had resistant disease. The 36 patients (23%) with inadequate cytoreduction after the 6 d of ara-C alone were randomly assigned either to no further chemotherapy (21 patients) or to 3 d of AMSA (15 patients). The CR rates after one course were 14% and 53%, respectively (P = 0.01), and the fractions with resistant disease were 76% and 40%, respectively. The fractional reduction of leukaemia cells in the day 6 bone marrow aspirate specimen (P < 0.0001) and the reduction in the leukaemia cell mass measured in the day 6 marrow biopsy (P = 0.001) were the strongest predictors for achieving CR versus having residual disease in univariate analyses. The median duration of remission was 5 months, but seven patients (10%) remain in CR after 30-92 + months. Among the 140 patients who received only the 6 d of ara-C, the pretreatment albumin (P = 0.002) and lactate dehydrogenase (P = 0.01) levels were the strongest predictors of response in univariate analyses, but only the albumin remained significant (P = 0.01) in a stepwise logistic regression analysis. Those patients with albumin > 4.0 mg/dl and LDH < 125% of normal had a 71% CR rate, and only 16% had resistant disease. Thus, pretreatment characteristics and rapid cytoreductin in the day 6 bone marrow sample identified a favourable subset of patients with AML in first relapse, some of whom responded quite well to 6 d of ara-C alone and have had long disease-free remissions.

Acute Disease↗
PubMed1992

Mechanisms of citral phototoxicity.

Citral, a monoterpene aldehyde synthesized by several plant genera, has been reported to exhibit antimicrobial activity. For the first time, we report that critral exhibits UV-A (315-400 nm) light enhanced oxygen-dependent toxicity against a series of Escherichia coli strains differing in DNA repair and catalase proficiency. Those E. coli strains carrying a gene leading to catalase deficiency (katF) are particularly sensitized to inactivation by citral and UV-A treatment when compared to catalase proficient strains (katF+). Consistent with these in vivo observations, citral when treated with UV-A in vitro produces H2O2. When tested against Fusarium oxysporum and F. solani, fungal root pathogens of Citrus, enhanced toxicity by citral in the presence of UV-A was demonstrated, while dark toxicity was negligible. When the plasmid pBR322 was treated with citral in the presence of UV-A, a change in conformation from the covalently closed circular to the open circular and, ultimately, the linear form was observed. The change in plasmid conformation corresponded to a reduction in transforming activity. Holding plasmid DNA which had been treated with UV-A light in the presence of citral at 4 degrees C for 22 h in the dark resulted in continued degradation of the DNA and loss of transforming activity. Holding plasmid DNA treated with UV-A or citral alone under identical conditions had no detectable effect on either plasmid conformation or transforming activity.

Acyclic Monoterpenes↗
PubMed1992

A pilot study of prophylactic aerosolized amphotericin B in patients at risk for prolonged neutropenia.

Invasive aspergillosis continues to be a significant cause of morbidity and mortality in patients with prolonged neutropenia. We performed a phase I trial of escalating doses of aerosolized amphotericin B given by a face mask nebulizer system with a disposable bacterial exhale filter. Five, 10, 15, and 20 mg of drug were dissolved in sterile water and inhaled over 10 to 15 minutes twice daily. Tolerance was studied in 26 patients (18 transplant recipients, and 8 leukemia patients). No side effects were observed at any dose level. Prophylactic treatment ended for 14 patients (54%) when intravenous (IV) amphotericin B was begun empirically for antifungal coverage following fevers. Eleven patients (43%) continued inhaled amphotericin B until blood counts recovered. One patient was taken off study when she developed cardiogenic pulmonary edema. No patient developed clinically suspicious or pathologically documented infection with invasive aspergillosis. Prophylactic aerosolized amphotericin B is well tolerated at 5, 10, 15, and 20 mg twice daily dosing. In addition, prophylactic aerosolized amphotericin B does not appear to sensitize patients to the subsequent use of IV amphotericin B. Although this study suggests that prophylactic inhaled amphotericin B is well tolerated and effective, a large scale controlled trial is needed.

Adult↗
PubMed1992

Phase I study of busulfan, cyclophosphamide, and timed sequential escalating doses of cytarabine followed by bone marrow transplantation.

In both animal models and human studies in leukemia, residual disease on day 8 following myelosuppressive therapy is in a proliferative phase and therefore may be sensitive to the S-phase specific drug cytarabine. Based on this concept, 17 patients with refractory or relapsed leukemia or lymphoma undergoing either autologous or allogeneic bone marrow transplantation (BMT) were treated on a Phase I protocol using high doses of busulfan (16 mg/kg, days -10, -9, -8, -7) and cyclophosphamide (120 mg/kg, days -6, -5) followed by escalating doses of a 48-h continuous infusion of cytarabine (starting dose 1000 mg/m2/48 h, days -3, -2). Ten patients received autologous transplants (two with Hodgkin's disease, seven with non-Hodgkin's lymphoma, one with chronic myelogenous leukemia (CML) in blast phase). Seven received allogeneic BMT (two with refractory acute myelocytic leukemia (AML), one with refractory acute lymphoblastic leukemia (ALL) undergoing a second BMT, one with Burkitt's-type leukemia, one with ALL in fifth relapse and two with CML in accelerated/blast phase). Two of these patients received a T cell-depleted haploidentical transplant. The maximum tolerated dose of cytarabine was 1500 mg/m2/48 h; a pulmonary syndrome including dyspnea, hypoxemia, and interstitial infiltrates which responded to aggressive diuresis was the dose limiting toxicity. Of the 10 patients who received cytarabine doses of 2000 or 2500 mg/m2/48 h, five patients developed adult respiratory distress syndrome (ARDS) with three patients requiring intubation; two recovered. Of the nine patients with lymphoma, seven responded with complete tumor clearance (CTC) with two patients tumor-free 13 and 15 months post-BMT, one remained refractory and one died too early to evaluate (TETE).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Inhibition of hydroxymethylglutaryl coenzyme A reductase activity induces a paradoxical increase in DNA synthesis in myeloid leukemia cells.

The effects of competitive inhibition of hydroxymethylglutaryl coenzyme A (HMG CoA) reductase by compactin on the in vitro proliferation of peripheral blood myeloid leukemia cells were studied using the cells from 45 patients with acute myeloid leukemia or chronic myelogenous leukemia in blast phase. The cells from 58% of these patients showed a dose-related inhibition of DNA synthesis when incubated with compactin. Unexpectedly, cells from 18% of the patients were resistant to the inhibitory effects of compactin on DNA synthesis and responded to the HMG CoA reductase inhibition with an actual increase in the incorporation of 14C-labeled thymidine into DNA. Another 18% of the patients studied displayed both inhibition and stimulation of DNA synthesis in a biphasic response depending on the particular concentration of compactin used. The maximum enhanced rates of cellular DNA synthesis were observed with lower compactin concentrations (5 x 10(-7) mol/L) than were required for maximum inhibition of DNA synthesis (10(-5) mol/L). Leukemia cells displaying a stimulated response to compactin had a significantly lower baseline DNA synthetic rate than did cells that showed an inhibitory response of DNA synthesis to compactin. There was no correlation between these cells' varying DNA synthetic response to compactin and measures of baseline HMG CoA reductase activity or acetate conversion to cholesterol. Whereas the observation of cellular DNA synthesis stimulation by HMG CoA reductase inhibition has not been observed in other mammalian cells and seems paradoxical, explanations may emerge in light of our growing knowledge concerning the importance of isoprenylation for the function of certain cell regulatory proteins.

Cell Cycle↗
PubMed1991

Interphase cytogenetic analysis detects minimal residual disease in a case of acute lymphoblastic leukemia and resolves the question of origin of relapse after allogeneic bone marrow transplantation.

We used in situ hybridization with a probe for the X chromosome to study interphase cells of bone marrow and peripheral blood specimens from a male patient with acute lymphoblastic leukemia characterized by hyperdiploidy, including trisomy X. In a posttreatment bone marrow specimen, which was interpreted as a regenerating bone marrow morphologically and which demonstrated a normal karyotype cytogenetically, trisomy X was found in 16 of 1,000 interphase cells. This finding indicated the presence of leukemic cells that were undetected by conventional morphologic and cytogenetic techniques (ie, minimal residual disease). Cytogenetic studies of a relapse specimen obtained after a sex-mismatched bone marrow transplant showed only a normal female karyotype in each of 40 metaphase cells, suggesting that the relapse occurred in donor cells. However, interphase analysis demonstrated trisomy X in more than 80% of interphase cells and indicated that the relapse was of the original clone and was not a transformation of donor cells. This case illustrates that interphase analysis can be useful as an adjunct to conventional cytogenetic analysis in the detection of minimal residual disease and in the analysis of interphase cells that are not accessible to routine cytogenetic methods. It also illustrates that previously reported instances of relapse of leukemia in donor cells could have been incorrect if supported by cytogenetic data alone.

Adult↗
PubMed1991

Therapy for acute myeloid leukemia and acute lymphoblastic leukemia in adults.

Using intensive induction chemotherapy, primarily with combinations of an anthracycline and cytarabine, complete remission rates of greater than 70% are now achieved in patients with acute myeloid leukemia under the age of 60 years. The treatment of elderly patients with acute myeloid leukemia is difficult and remains controversial. The prognosis for both adults and children with acute lymphoblastic leukemia has improved as more extensive chemotherapy regimens have been used. Recently, a group of leukemias have been identified that have features of both acute lymphoblastic leukemia and acute myeloid leukemia, and these are referred to as biphenotypic or hybrid leukemias. These hybrid leukemias represent an important subgroup, which appears to have a worse outcome regardless of the therapy administered.

Adult↗