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Biomedical subjects

A D Ho

Publications and source records attributed to A D Ho.

At least 19 recordsLinked to original sources
PubMed1992

S1 nuclease hypersensitive sites in an oligopurine/oligopyrimidine DNA from the t(10;14) breakpoint cluster region.

Recurring chromosomal translocations are frequently seen in cancers, especially in leukemias and lymphomas. The genes affected by these chromosomal translocations appear to play an important role in oncogenesis. The mechanism underlying the formation of chromosomal translocation is a subject under extensive study. In chromosomal translocations involving the Ig and TCR loci, complete heptamer-spacer-nonamer signal motifs are usually present at the break of the Ig and TCR genes, indicating the involvement of V-D-J recombinase(s). On the other hand, in only about 50% of the cases signal motif sequences have been found at the break in the other participating chromosome, suggesting that different mechanisms may be involved in the scission of the corresponding chromosome. Here we report the identification of an oligopurine/oligopyrimidine DNA in the t(10;14) breakpoint cluster region associated with T-cell acute lymphoblastic leukemia. S1 nuclease mapping revealed multiple S1 hypersensitive sites in the oligopurine/oligopyrimidine DNA. These data suggest a role for oligopurine/oligopyrimidine sequences (non-B DNA) in the formation of chromosomal translocation.

Base Sequence↗
PubMed1992

Deficiency in interferon production of peripheral blood leukocytes from patients with non-Hodgkin lymphoma.

In search for a rationale for the use of interferons (IFNs) in treatment of non-Hodgkin lymphoma (NHL), we have investigated the IFN system of 13 patients with low-grade NHL, 15 patients with high-grade NHL, and 20 patients with chronic lymphocytic leukemia or leukemic immunocytoma (CLL/IC). Production of IFN induced by phytohemagglutinin (PHA), concanavalin A (Con A), pokeweed mitogen (PWM), Corynebacterium parvum, Herpes simplex virus (HSV), Newcastle disease virus (NDV), and interleukin 2 (IL-2) were studied in the peripheral leukocytes from the patients and from 21 control persons by means of a whole blood technique. All three groups of patients with NHL had significantly reduced production upon stimulation by NDV (p ranged between 0.0038 and less than 0.0001) compared to controls. Similarly, C. parvum also induced lower titers of IFN in the leukocytes of patients with non-leukemic NHL (p = 0.0015 for low-grade NHL and p = 0.0038 for high-grade NHL). When stimulated by PHA, the IFN response of all groups of patients was within normal range. With the exception in low-grade NHL, Con A also induced normal titers of IFN in the patients with NHL. The levels of IFN induced by PWM, HSV, and IL-2 were very low and no differences between controls and patients could be found. As NDV and C. parvum induce mainly IFN-alpha and the mitogens PHA and Con A mainly IFN-gamma, our results suggest that there is a deficiency in the IFN-alpha response in the patients with NHL but normal response in IFN-gamma.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Genomic organization of the putative human homeobox proto-oncogene HOX-11 (TCL-3) and its endogenous expression in T cells.

The HOX-11 (TCL-3) gene, which is abnormally expressed in the leukemic cells of some patients with T-cell acute lymphoblastic leukemia, is a new member of the homeobox gene family. It is structurally altered by the t(10;14) chromosomal translocation, resulting in head-to-tail juxtaposition of HOX-11 with the T-cell receptor delta-chain gene. In order to understand the normal functions of HOX-11 and its role in T-cell leukemia, we have determined the exon-intron structure of the HOX-11 gene. By using oligonucleotide primers flanking an intron of the HOX-11 gene, we have developed a quantitative reverse transcription-polymerase chain reaction (RT-PCR) assay for the expression of HOX-11. We detected HOX-11 expression in multiple cell lineages including normal T cells and two T-cell lines in which the HOX-11 gene appeared to be unaltered in structure. Our results suggest that deregulation of the endogenous expression of HOX-11 in normal T cells represents an essential step towards the formation of this type of T-cell leukemia.

Amino Acid Sequence↗
PubMed1992

Induction of intracellular and plasma 2',5'-oligoadenylate synthetase by pentostatin.

Similar to interferon alpha, pentostatin is highly effective in hairy cell leukemia and moderately active in other chronic lymphoid malignancies. In ten patients with hairy cell leukemia (HCL) and seven patients with other B-cell chronic leukemias (BCL), we have studied the intracellular 2',5'-oligoadenylate synthetase (2,5OAS) activity of the mononuclear cells before, 4 h, 24 h, and 48 h after pentostatin administration. In patients with HCL the median level of intracellular 2,5OAS increased 4.6-fold at 4 h and 11.5-fold at 24 h compared to the pretreatment value. Among the other seven patients, the median intracellular 2,5OAS remained unchanged in three patients and rose slightly by 2 to 14 times in four patients. Eleven patients (eight with HCL and two with BCL) responded to pentostatin. The median increase in 2,5OAS among the responders was 13.0-fold (range 4.8-30.0) whereas that among non-responders was 2.2-fold (range 0.2-6.3). The difference was highly significant (p less than 0.0001). In five of the total seventeen patients, the plasma levels of 2,5OAS activity were also determined and changes in plasma levels paralleled those measured intracellularly. To determine if the elevation of 2,5OAS is mediated by induction of interferon alpha, the expressions of mRNA for interferon alpha and beta were investigated by means of reverse transcription and polymerase chain reaction using the corresponding sense primers. In none of the five patients thus studied could we find an induction of mRNA for interferon alpha or beta in the leukemic cells during treatment with pentostatin. Thus, response to pentostatin correlates with induction of 2,5OAS directly and the 2',5'-oligoadenylate system seems to be involved in cytotoxicity.

2',5'-Oligoadenylate Synthetase↗
PubMed1991

Detection of bone marrow infiltration by non-Hodgkin's lymphoma--comparison of histological findings, analysis of gene rearrangements, and examination by magnetic resonance imaging.

The histological examination of bone marrow specimens is one of the standard procedures in staging non-Hodgkin's lymphoma. To investigate the validity of a conventional unilateral iliac crest biopsy, we performed a prospective study comparing histological findings with analysis of gene rearrangements in bone marrow samples and magnetic resonance imaging of bone marrow. Twenty-seven consecutive patients with non-Hodgkin's lymphoma (ten with high grade, seventeen with low grade) were studied. In twelve patients, histological examination revealed bone marrow infiltration. Results of histology and magnetic resonance imaging were discordant in three of the twenty-seven patients. With magnetic resonance imaging, suspected infiltration was found in two patients without histological evidence for bone marrow involvement in the disease. In one patient, an infiltration was described by histology but MRI revealed no pathological findings. In this case, DNA analysis confirmed bone marrow infiltration by detection of a clonal rearrangement of the immunoglobulin heavy chain gene. Analysis of gene rearrangements was performed in ten patients. As examined by histology, five of them had bone marrow involvement in the disease and five had not. In all these cases, analysis of gene rearrangements confirmed the histological findings. Our data show that, despite the small volume of bone marrow specimens, the sensitivity of an iliac crest biopsy seems to be high in staging non-Hodgkin's lymphoma.

Adult↗
PubMed1991

Etoposide in acute leukemia. Past experience and future perspectives.

Etoposide as a single agent is active in relapsed and refractory acute myelogenous leukemia (AML), with complete responses (CR) rates of 10% to 25%. The drug has been safely combined with cytarabine, azacytidine, vinca alkaloids, and anthracyclines, inducing remission rates of 20% to 60% in patients with previously treated AML. The experience with etoposide in acute lymphoblastic leukemia is less extensive, but the drug seems to be active in combination with cytarabine or aclacinomycin. In addition, etoposide is combined with cytarabine and anthracyclines for the primary treatment of AML. The response rates thus achieved are comparable with those obtained with standard regimens. A Phase I/II trial was initiated to study the efficacy of the NOVE combination (mitoxantrone [10 mg/m2/d, days 1 to 5] plus etoposide [100 mg/m2/d for 3, 4, or 5 days] in patients with refractory AML. The results showed that extended duration of etoposide administration is associated with higher CR rates. Overall, a CR rate of 43% was achieved in 61 patients. A sequential regimen with IDAC (idarubicin/cytarabine) and NOVE was designed for primary treatment of adult patients with AML. Cycles of IDAC or NOVE are applied depending on response. The results of the pilot study with this strategy were encouraging with 18 of 20 patients achieving CR. Further studies are under way to verify the efficacy of this strategy.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1991

The tcl-3 proto-oncogene altered by chromosomal translocation in T-cell leukemia codes for a homeobox protein.

The t(10;14)(q24;q11) chromosomal translocation found in malignant cells of 5-10% of patients with T-cell acute lymphoblastic leukemia (T-ALL) involves the T-cell receptor delta chain gene on chromosome 14 and a breakpoint cluster region on chromosome 10. The candidate proto-oncogene tcl-3, thought to be involved in the pathogenesis of t(10;14) T-ALL, was cloned and found to be elevated in expression in leukemic cells harboring the t(10;14) translocation. Sequence analysis revealed that tcl-3 is a new homeobox-containing gene. Comparison of the tcl-3 cDNA and its 5' genomic sequences with DNA sequences from the t(10;14) translocation breakpoints showed that this gene is structurally altered in four patients with t(10;14)(q24;q11) T-ALL. These findings suggest that homeobox-containing genes that normally act as transcription factors may contribute to T-cell leukemogenesis when abnormally expressed.

Amino Acid Sequence↗
PubMed1991

Decrease in soluble CD8 antigen levels in splenectomized patients as an index for reduced suppressor/cytotoxic cell activity.

To investigate the effect of splenectomy on lymphocyte subpopulations we monitored changes in serum concentrations of soluble suppressor/cytotoxic (sCD8) and soluble helper/inducer (sCD4) antigen in 11 splenectomized patients. Indications for splenectomy were hereditary spherocytosis in 2, idiopathic thrombocytopenic purpura in 2, gastric carcinoma in 4, Hodgkin's disease in 2 and pancreatitis in 1 patient. Lymphocyte subpopulations were also analyzed by means of conventional immunophenotyping with monoclonal antibodies to CD4 and CD8. We consistently found an early postoperative drop of sCD8 and sCD4 levels within the first week after splenectomy, paralleling changes in the percentages of CD4+ and CD8+ lymphocytes. While alterations of lymphocyte subsets in the peripheral blood were completely reversible and sCD4 levels returned to preoperative values, sCD8 concentrations remained suppressed even 3 months after splenectomy. SCD8 levels at the nadir and those 3 months after splenectomy were significantly lower than preoperative values (P = 0.003, P = 0.149 respectively). Since sCD8 levels reflect suppressor/cytotoxic cell activity, we suggest that suppressor cell activity is reduced in splenectomized patients.

Adult↗
PubMed1991

Chemotherapy of chronic haematological malignancies.

After years of stagnation in the treatment of chronic haematological malignancies, some interesting agents have emerged which might improve the prognosis of these diseases. For chronic leukaemias of lymphoid lineage, three new chemical agents, all purine analogues, seem to be of particular interest. Pentostatin is a specific inhibitor of ADA and has been shown to be highly efficient in producing CR in patients with HCL. Its relative merit compared with IFN-alpha for the treatment of HCL is being studied in ongoing randomized trials. Pentostatin is also active in B-CLL and promising activities have been demonstrated in T- or B-PLL and ATCL. Fludarabine is an analogue of adenine which is resistant to the deamination of ADA. It has been reported to be highly active for patients with both pretreated or non-treated B-CLL. CR rates of 13% with overall response rates of 57% can be achieved, even in heavily pretreated patients. Its activity in the other lymphoid malignancies is not yet known. CdA, a substrate analogue of ADA, has also produced encouraging results in B-CLL, HCL and T cell malignancies, and in some patients with just one single course. Thus far, experience with this drug comes from one institution and requires further confirmation. For chronic myeloproliferative diseases, little progress has yet been made. Although IFN-alpha seems to be active in CML and to result in cytogenetic remissions in bone marrow, a definite advantage of this biological agent over conventional chemotherapy as regards survival and life quality has not yet been proven. Allogeneic bone marrow transplantation is beneficial for those patients who are eligible. No remarkable advances have been made in the treatment of myeloproliferative disorders except for the development of an antiplatelet drug, anagrelide. This agent seems to be highly effective in controlling thrombocytosis. The relative merit of this agent as compared with IFN-alpha, as well as the impact of this agent on the survival and on life-quality of patients with myeloproliferative disorders, have yet to be defined.

Antineoplastic Agents↗
PubMed1991

Utilization of recombinant human GM-CSF to enhance peripheral progenitor cell yield for autologous transplantation.

Evidence has accumulated which indicates that efficacy of chemotherapy correlates with dose intensity and with total dose. For most cytotoxic agents, the major limiting factor for escalation of dose intensity is myelotoxicity. Attempts have been made to circumvent myelotoxicity by autologous bone marrow transplantation. Recently, it has been demonstrated that progenitors enriched from the peripheral blood can also be used successfully for autografting. The concentration of progenitor cells in peripheral blood is lower than that in bone marrow but myelosuppressive chemotherapy or hematopoietic growth factors, or a combination of both can be exploited to enhance the progenitor cell yield. The studies reported here are sequential. In the first study, eight patients with advanced Hodgkin's disease received myelosuppressive regimen consisting of cytarabine (100 mg/m2/12h SC days 1 to 5) and daunorubicin (45 mg/m2/d, days 3 and 4). Progenitor cell leukapheresis was performed during the rebound phase of hematopoiesis. All eight patients were treated with super-dose chemotherapy with progenitor cell transplantation. One patient died of CNS toxicity 48 days after transplantation but all other seven had sustained engraftment. In the second study, human recombinant GM-CSF (at 250 micrograms/m2/d as continuous infusion) was administered to twelve patients. Leukapheresis was started at a white blood count (WBC) of greater than 10 x 10(9)/L and the dosage of rhGM-CSF adjusted to keep the WBC between 10 x 10(9)/L and 20 x 10(9)/L. The median duration of rhGM-CSF application was 11.5 days and a median number of six leukaphereses performed. The median increase in the number of granulocyte-macrophage colony forming units (CFU-GM)/ml of peripheral blood was 8.5 fold.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Assessment of bone marrow infiltration by magnetic resonance imaging in patients with hairy cell leukemia treated with pentostatin or alpha-interferon.

The bone marrow of five patients with progressive hairy cell leukemia was examined histologically and by magnetic resonance imaging in a prospective study. Iliac crest biopsies and magnetic resonance scans were performed before and after nine months of therapy with pentostatin (four patients) and alpha-interferon (one patient). T1-weighted scans were evaluated quantitatively and in terms of their visual appearance in three regions of interest (lumbar spine, pelvis and femur). In contrast to bone marrow histology, it was possible to detect differences in the degree of infiltration between these marrow regions in four patients by magnetic resonance imaging. After treatment, three patients had no residual bone marrow infiltration as determined histologically; in parallel, the magnetic resonance images had normalized. The remaining two patients achieved partial remission: marrow infiltration was estimated to be 20% histologically, corresponding well to the signal reduction obtained by magnetic resonance imaging. These data suggest that magnetic resonance imaging of the bone marrow is a sensitive method for assessing responses to treatment with pentostatin and alpha-interferon in patients with hairy cell leukemia.

Adult↗
PubMed1990

Pentostatin in refractory chronic lymphocytic leukemia: a phase II trial of the European Organization for Research and Treatment of Cancer.

Pentostatin was used to treat 26 patients with advanced B-cell chronic lymphocytic leukemia resistant to conventional treatment. Twenty patients had progressive disease on previous regimens and six had had partial remission and then relapsed 3-34 months after previous chemotherapy. Eleven patients had previously been treated with three different regimens. 10 had been treated with two regimens, and five had been treated with one regimen. Pentostatin was administered at a dosage of 4 mg/m2 weekly for 3 weeks, then 4 mg/m2 every other week for 6 weeks and once a month for 6 months. Seven of 26 assessable patients (27%) achieved partial remission and five (19%) achieved clinical improvement. The median duration of partial remission until relapse or death was 210 days. Myelosuppression was minor and transient in responsive patients, indicating some degree of selective effect on lymphocytes. Except for one patient who died of cerebral hemorrhage during the first 6 weeks of treatment, no drug-related deaths were registered. Major toxic effects included nausea in 17 patients (mainly grade 1), infections in 15, and liver enzyme elevations in five. Thus, pentostatin is active, even in patients with advanced B-cell chronic lymphocytic leukemia that is refractory to multiple chemotherapy regimens. Response can be achieved with mild myelosuppression.

Adult↗
PubMed1990

Mitoxantrone/high-dose Ara-C and recombinant human GM-CSF in the treatment of refractory non-Hodgkin's lymphoma. A pilot study.

Previous study has shown that the combination of mitoxantrone (Novantrone, NO) and Ara-C (AC) (NOAC) was active in refractory non-Hodgkin's lymphoma (NHL) but myelosuppression was dose-limiting. In a pilot study, we investigated the effects of recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) after NOAC chemotherapy in patients with refractory NHL. NO was applied at a dosage of 10 mg/m2/day on days 2 and 3 and AC at 3 g/m2/12h on days 1 and 2. RhGM-CSF was administered at 250 ug/m2/day as a continuous i.v. infusion from day 6 until the neutrophils were greater than 3.0/nl for 3 consecutive days. Twenty-three patients from five of the nine participating centers were treated with NOAC chemotherapy plus rhGM-CSF, whereas 14 patients from the other four centers received chemotherapy alone. With rhGM-CSF, the median duration of severe neutropenia (less than 0.5/nl) after NOAC was 8 days versus a median of 13 days without rhGM-CSF (P = 0.0058), and that of thrombocytopenia (less than 20.0/nl), 3 days versus 7 days (P greater than 0.4, NS). The rates of infections and stomatitis were 25% and 17%, respectively, for patients treated with rhGM-CSF as compared to 53% (P = 0.0547, NS) and 60% (P = 0.0078), respectively, without rhGM-CSF. The following side effects were associated with the administration of rhGM-CSF: pleural and/or pericardial effusions in five patients, thrombosis in two patients, bone pain in two patients, and respiratory distress syndrome in one patient. A complete remission was achieved in nine of the 23 patients treated with NOAC plus rhGM-CSF, and in two of the 14 patients treated with chemotherapy alone. The median survival of patients treated with rhGM-CSF was not reached at 400 days and seemed to be longer than that of patients treated with chemotherapy alone (median, 109 days; P = 0.036). RhGM-CSF after chemotherapy can be applied safely to patients with NHL, shorten the period of severe cytopenia, reduce the rates of stomatitis, and did not seem to cause adverse effects on response.

Adolescent↗
PubMed1990

Clinical implications of increased plasma levels of CD8 in patients with hairy cell leukemia.

Plasma levels of soluble T-suppressor/cytotoxic antigen (sCD8) were measured at diagnosis or before systemic treatment in 69 patients with hairy cell leukemia (HCL). The 49 nonsplenectomized patients were characterized by high concentrations of sCD8 antigen as compared with 17 controls (P less than .0001). The median sCD8 level in non-splenectomized patients was 1,050 U/mL (range: 160 to 2,400 U/mL) and was significantly higher (P less than .0001) than the median of 275 U/mL (range: 20 to 1,080 U/mL) in splenectomized patients. The relationship of sCD8 to clinical response to subsequent interferon alpha (IFN alpha) treatment was analyzed. Patients who showed subsequent hematologic response with normalization of all blood counts had significantly lower levels of sCD8 concentrations at diagnosis than those who did not (P = .0056). Furthermore, normalization of sCD8 during IFN alpha treatment paralleled the achievement of normal counts in peripheral blood, whereas soluble interleukin-2 receptor (sIL-2R) levels remained high in most patients after 12 to 15 months of treatment. We speculate that activation of suppressor/cytotoxic T cells might play a role in myelosuppression, and its modulation during treatment with IFN alpha correlates with normalization in peripheral blood counts.

Adult↗
PubMed1990

Activation of lymphocytes induced by recombinant human granulocyte-macrophage colony-stimulating factor in patients with malignant lymphoma.

To investigate effects of recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) on lymphoid cells in vivo, we monitored changes in absolute lymphocyte counts, plasma concentrations of soluble interleukin-2 receptor (sIL-2R) and soluble cytotoxic/suppressor (sCD8) antigens, and phenotypic changes of surface membrane antigens of peripheral mononuclear cells from 14 patients with malignant lymphoma treated with rhGM-CSF. Eight of the 14 patients had relapsed or had refractory non-Hodgkin's lymphoma (NHL) and received rhGM-CSF after intensive chemotherapy with novantrone (NO) and high-dose Ara-C (AC) (NOAC) as salvage regimen. Six other patients with NHL or Hodgkin's disease (HD) were in complete remission and treated with rhGM-CSF to enhance peripheral hematopoietic progenitor cell harvest for autografting. An increase in absolute lymphocyte count at the zenith of leukocyte elevation and a drastic increase in concentration of sIL-2R from a median of 565 U/mL to 6,700 U/mL on rhGM-CSF infusion were found in all patients. There was also a moderate increase in sCD8 levels from a median of 277 U/mL to 470 U/mL. Ten patients were available for serial studies of phenotypic changes in surface membrane antigens. A significant increase in CD25+ (IL-2R+) (P = .0020) and CD4+ (P = .0137) lymphocytes was observed in all patients, but no significant change in CD3+, CD8+, TCR delta 1+, or CD19+ cells. Elevations in absolute lymphocyte counts or in concentrations of sIL-2R or sCD8 were not observed in four other patients during recovery from intensive chemotherapy without rhGM-CSF support. Our results provide evidence that administration of rhGM-CSF might activate lymphocytes in vivo. The impact of this activation on the remission rate and duration, as well as survival in patients with NHL, warrants further investigation.

Antigens, CD↗