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We analyzed the structural alteration of the p53 gene, by Southern blotting with conventional and/or pulsed-field gel electrophoresis, in patients with Philadelphia chromosome-positive leukemia (chronic myelogenous leukemia; CML, 34 cases and acute leukemia; AL, 5 cases). We found an alteration of the p53 gene in one of 5 AL patients. Loss of heterozygosity was detected in two CML patients with i(17q) chromosome, but we could find no other alterations in the remaining CML patients.

The Philadelphia (Ph) chromosome can be detected in the vast majority of patients with chronic myelogenous leukemia (CML). We performed a long-range analysis of chromosomal translocation junction by pulsed-field gel electrophoresis (PFGE) techniques, to examine whether molecular evidence of a reciprocal Ph translocation exists in Ph-positive CML as well as Ph-negative, M-BCR rearrangement-positive CML. The rearrangement within M-BCR and ABL was detected in all patients including nine Ph-positive CML, and three Ph-negative CML. The rearranged 3'-abl fragments showed comigration with rearranged 5'-bcr fragment in rare-cutting restriction enzyme digests in all patients with Ph-positive CML. Thus, the physical linkage of the 3' part of ABL to the 5' side of M-BCR on 22q-chromosome was shown. The same linkage was also demonstrated in all three patients with Ph-negative CML. Meanwhile, the rearranged 3'-bcr fragments showed comigration with rearranged pHabl5' (or T39-1-2) fragments in all patients with Ph-positive CML, indicating the linkage of the 5' end of ABL to the 3' part of M-BCR on 9q+ chromosome. However, this linkage was absent in two Ph-negative CML patients who could be studied. The results suggest that a genomic insertion of 3' ABL into M-BCR in Ph-negative CML occurs by a single cytogenetic event rather than a two-translocation mechanism.

Fifty patients with infections associated with hematological disorders were treated with ceftazidime (CAZ). Among them 44 cases were evaluable, including 21 with acute leukemia, 17 with malignant lymphoma, and 6 with other hematological disorders. Excellent responses were observed in 15 patients (34.1%) and good responses in 15 (34.1%), with an overall efficacy rate of 68.2%. The efficacy rate among sepsis and suspected sepsis cases was 67.6%. This treatment was also effective in 7 of 10 cases in which neutrophil counts were less than 500/mm3 through the course of administration. Laboratory abnormalities included mild eosinophilia in 1 case, slight elevation of GOT in 1 case and slight elevation of GPT in 1 case. These results suggest that CAZ is an effective and safe antibiotics for the treatment of infections in patients with hematological disorders.

We evaluated clinical effects and toxicities of a combination treatment with cefminox (CMNX) and fosfomycin (FOM) for infections complicated with hematological disorders in 56 patients. Among those, 52 patients including 22 with malignant lymphoma, 19 with acute leukemia, and 11 with other hematological disorders were evaluable. Excellent and good responses were obtained in 33 (63.5%) of the 52 patients. This treatment was also effective in 5 of 9 cases in which granulocyte counts were less than 500/mm3 through the course of administration. Side effects were observed in only one patient. Mild nausea occurred but was not serious. These results indicate that the combination of CMNX and FOM is an effective and safe regimen for the treatment of infections complicated in patients with hematological disorders.

Imipenem/cilastatin sodium (IPM/CS), which has a broad spectrum of activity against both Gram-positive and -negative bacteria including methicillin-resistant Staphylococcus aureus and Pseudomonas aeruginosa, was used as the second choice for severe infections associated with hematological disorders. Sixty-five patients were treated with IPM/CS. Among them, 53 patients were evaluable for the clinical efficacy. Twelve patients were not evaluable due to the following reasons: 5 patients were treated with combinations of other regimens such as cefzonam, cefmenoxime, ciprofloxacin or gamma-globulin, 5 were patients to whom IPM/CS was administered as the first choice, and the remaining 2 patients were thought to be suffering not from febrile infections but from febrile tumor. Excellent responses were observed in 10 (18.9%) patients and good responses in 23 (43.4%) patients, with an overall rate of efficacy of 62.3%. The efficacy in septic patients was 75% (3/4), and that in patients whose peripheral granulocytes were continuously below 100/microliter was also 75% (6/8). Two patients who suffered from tumor fever and 5 patients who had received no chemotherapy before IPM/CS administration were included in the final evaluation of side effects. Side effects were observed in 16 patients (16/60, 26.7%). In a 61 years, female patient, a skin eruption was found 4 days after IPM/CS therapy was started. In 15 patients, mild gastrointestinal symptoms such as nausea and vomiting were identified within a few days after IPM/CS treatment was started. Abnormal laboratory data such as eosinophilia, liver dysfunction or renal dysfunction were also identified in 4 patients (4/60, 6.7%). Degrees of these abnormalities were very slight, however, and the continuation of treatment was not disturbed. These results indicated that IPM/CS was an effective second line regimen of chemotherapy for the treatment of severe infections in patients with hematological disorders.

A female patient in whom acute nonlymphocytic leukemia (ANLL, FAB-M6) developed during treatment of hepatocellular carcinoma (HCC) is described. Two years after partial hepatectomy and subsequent chemotherapy, leukemia developed following a 2 month preleukemic stage. Chromosomal analysis revealed an abnormal karyotype, 46,XX,-5, + der(5)t(3;5)(q25;q31). The balanced translocation t(3;5) has been observed in all types of ANLL and MDS except for ANLL M3 subtype. We summarize patients with ANLL M6 and t(3;5).

Cytogenetic and molecular aspects of Ph-positive leukemia are described in comparison with those of Ph-positive CML. Chromosomal characteristics of Ph+AL are; 1) mixture of a normal karyotype at diagnosis, 2) frequent combination with +Ph, +21, +6, +8, or -7, 3) recovery of a normal karyotype at remission. Additional chromosome changes at myeloid blast crisis (BC) of CML are characterized by +Ph, i(17q), +8, or +19. Meanwhile, lymphoid BC exhibits +Ph, +21, but not i(17q) or +19. There seems no cytogenetic difference between Ph+AL and lymphoid BC of CML, but i(17q) may be specific for CML BC. Eight patients with Ph+AL were studied with pulsed-field gel electrophoresis (PFGE) to examine the break site within ABL and BCR genes. One case had a M-BCR rearrangement and the remainder a rearrangement upstream of M-BCR. Minor-BCR rearrangement occurs seldom in CML but is detected in approximately a half of the reported cases of Ph+AL. ABL was rearranged within 1st or 2nd intron in all 8 cases. ABL breakpoints appear randomly distributed between exons 1b and 2 in both Ph+AL and CML.

In a case of Philadelphia chromosome (Ph1)-negative chronic myeloid leukemia (CML) without the Y chromosome, we investigated the differences, at the molecular level, from Ph1-positive CML. Using Southern blot analysis and in situ hybridization studies, we could demonstrate a rearrangement within the breakpoint cluster region (bcr), and the location of a bcr-abl fusion gene on chromosome 22. To our knowledge, this is the first case of Ph1-negative CML with a loss of the Y chromosome in which the molecular abnormalities are shown to be identical with those in Ph1-positive CML.

A patient with B-cell lymphoma with a chromosome rearrangement of t(14;19)(q32.3;q13.1) is reported. This patient had leukemic features and an aggressive clinical course. The histopathologic diagnosis was malignant lymphoma, small noncleaved cell. Chromosome analysis of the cells from a cervical lymph node and peripheral blood showed a reciprocal translocation between chromosome 14 with a break at band q32.3 and chromosome 19 with a break at band q13.1, to which the bcl-3 gene has been mapped. Monoclonal rearrangement of the JH gene was detected by Southern blot analysis. However, we could not detect rearrangement of the bcl-3 gene. This case also had a t(2;8)(q13;q24.1), but the c-myc gene remained in its germline. This is the first case with the reciprocal t(14;19) and 8q24 chromosomal breakpoint in a B-cell lymphoid malignancy.

Cefuzonam (CZON) which has a broad spectrum on both Gram-negative and Gram-positive bacteria including methicillin-resistant Staphylococcus aureus was evaluated in severe infections associated with hematological disorders. Sixty five patients were treated with CZON. Among them, 56 patients were evaluable for effectiveness. Nine patients were not evaluable because 3 patients were treated with combination of other antibiotics such as ceftizoxime, norfloxacin, ofloxacin, 1 patient was subjected to additional therapy of G-CSF and gamma-globulin, 4 were the patients with other disease than hematologic disorder (3 malignant mesotheliomas, 1 ovarian cancer), and the remaining one was prophylactically treated. Excellent responses were observed in 21 (37.5%) patients, good responses in 11 (19.6%) patients, with an overall efficacy rate of 57.1%. The efficacy rate in septic patients was 80% (4/5), and that in patient whose peripheral granulocytes were continuously below 100/microliters was 60% (3/5). Three patients who suffered from malignant mesothelioma, one patient who suffered from ovarian cancer, one patient who was treated prophylactically were included in the final evaluation of side effects. Side effects were observed in 2 patients (2/61, 3.3%). In a patient of 7 years, mild liver disfunction (GOT/GPT, 46/55) was found in 10 days after CZON treatment was started. In a patient of 65 years, mild appetite loss was identified in 2 days after CZON administration was begun. The liver disfunction was improved soon after the cessation of the treatment. The mild appetite loss disappeared while the treatment was continued. These results showed that CZON was an effective and safe antibiotic for the treatment of severe infections in patients with hematological disorders.

Using a human G-CSF cDNA as a probe, we analyzed the t(15;17) breakpoint by Southern blot analysis with conventional and/or pulsed-field gel electrophoresis in 12 patients with acute promyelocytic leukemia. The results did not show the rearrangement, deletion, or restriction fragment length polymorphism within the gene and in the surrounding sequences.

Reported is the second documented case in Japan of acute leukemia with Klinefelter's syndrome. The patient, a 52-year-old male, was admitted to hospital on July 9, 1983, after complaining of a fever and general malaise. The hematological examinations revealed a WBC count of 14,300/cmm with 32% being leukemic cells. Bone marrow aspiration disclosed a nucleated cell count of 687,000/cmm with 41.6% being leukemic cells consisting of myeloblasts. The endocrinic laboratory data showed a high level of urine gonadotropin and chromosomal studies revealed a 47,XXY karyotype. A diagnosis of acute myelogenous leukemia (M1) with Klinefelter's syndrome thus was derived from these findings.

We studied the effects of recombinant human interleukin-4 (IL-4) on colony formation by enriched hematopoietic progenitors. IL-4 alone did not support colony formation at all. When IL-4 was combined with granulocyte colony-stimulating factor (G-CSF), the number of pure neutrophil colonies increased three times over that supported by G-CSF alone. IL-4 added 5 days after the addition of G-CSF failed to exert this synergistic effect, indicating that IL-4 acts on the early stage of proliferation. The mapping experiments (sequential observation of colony formation) have clearly shown that IL-4 did not initiate progenitor cell proliferation. Based on these data, IL-4 may possess a direct action on progenitor cells; however, it can only act as a costimulant with G-CSF. In contrast, IL-4 had possible inhibitory effects on macrophage colony formation supported by interleukin-3 (IL-3) and macrophage colony-stimulating factor (M-CSF). In other words, IL-4 may induce progenitor cells to become sensitive to G-CSF and thereby induce neutrophil differentiation. Delayed addition experiments demonstrated that human IL-4, unlike murine IL-4, could support neither proliferation nor survival of erythroid burst or mixed colony forming cells. Neutrophil colony forming cells only survived and recovered after addition of G-CSF and erythropoietin on day 5 of incubation. On the other hand, IL-3 supported neutrophil, erythroid burst, and mixed colony forming cells as reported previously (Sonoda et al, Proc Natl Acad Sci USA, 85:4360, 1988). These results led us to propose that IL-4 possibly acts with more mature progenitor cells than those of IL-3 or granulocyte-macrophage (GM)-CSF.

In our chromosome study of 97 patients with myelodysplastic syndrome (MDS), six showed an unbalanced translocation between chromosomes 1 and 7 [-7, +der(1)t(1;7)(p11;p11)]. All of them had morphologic myelodysplasia in trilineage of bone marrow cells, and cytopenia was the major finding in the peripheral blood. All six patients had symptoms of infection at the time of diagnosis, and five showed immunologic abnormalities (polyclonal hypergammaglobulinemia in four and increased marrow plasma cells in three). None of the patients survived more than 11 months after the diagnosis; the median survival time was 4 months. Both of the two patients whose karyotypes were reexamined in the course of their disease showed karyotypic evolution accompanying the coincidental leukemic transformation. Six patients with MDS who had the same chromosome abnormality [t(1;7)] are described and their characteristic clinical features are presented.

We describe a chromosomal abnormality, 7q-, unrelated to the original karyotype in a patient with recurrent t(8;21) acute myeloblastic leukemia. The 7q-, del(7)(q22q34), was seen in otherwise karyotypically normal cells. Cyclophosphamide was administered for 5 months during the maintenance therapy. Our observations indicate that unrelated karyotypes, besides karyotypic evolution, may be implicated in tumor cell heterogeneity and may support the previous documentation of a possibly causal relationship between chemotherapy and development of 7q-. A larger study will be required to elucidate the biologic significance, if any, of the unrelated karyotypes.

Six patients with lymphoproliferative disorder of large granular lymphocytes (LDGL) were studied for chromosomal abnormalities. When the patients were divided into two groups depending on the expression of a mature antigen of T cell lineage, CD3, two with CD3+ phenotype had a stable disease, whereas three of the four patients with CD3- phenotype had marked hepatosplenomegaly and a highly aggressive disease. Chromosomal abnormalities were detected in four of six patients, indicating a clonal proliferation of large granular lymphocytes in individual patients. In particular, chromosomal abnormalities were found in three of the four patients with CD3- LDGL, all of which had a germ-line configuration of the T cell receptor beta-chain gene. Thus, the chromosomal abnormalities provide definitive evidence for the clonal origin of the expanded cells in the CD3- LDGL.

Six patients with chronic myelogenous leukemia and a complex Philadelphia (Ph1) translocation are described. The complex Ph1 translocations were a three-way translocation in five patients and a five-way translocation in one. Additional chromosomal aberrations were detected in four of five patients when the blastic crisis supervened. The median survival time was 42 months. The remaining patient died of acute myocardial infarction 23.5 months after the diagnosis of CML was made. There seems no difference between these six patients and those with the standard Ph1 with respect to clinical, hematologic and cytogenetic findings.

We observed double minute chromosomes (dmin) and a homogeneously staining region (HSR) in the same metaphase cells obtained from a retinoblastoma cell line, Y79. All of the 132 metaphases examined contained an HSR on the short arm of chromosome 1(1pHSR) and five cells (3.8%) had two to four dmin. To determine whether 1pHSR and dmin carried amplified N-myc sequences, we performed an in situ hybridization using an N-myc probe. Silver grains clustered on and along the 1pHSR, but not on the dmin. These findings indicate that the HSR on chromosome 1 is associated with amplification of N-myc in Y79 cells.

Using a human myeloperoxidase cDNA, we have mapped the human myeloperoxidase gene to chromosome 17 at q21.3----q23 by in situ hybridization to metaphase chromosomes from human lymphocyte preparations.

A 49-year-old nursery school teacher noticed epigastric discomfort and loss of appetite, and was hospitalized for diagnosis and treatment on Dec. 19, 1984. She was diagnosed to have Borrmann type 4 gastric cancer with Schnitzler's metastasis. After one month's administration of UFTM-O (UFT, mitomycin C, OK-432) subjective symptoms disappeared and improvement of the gastric lesion was demonstrated 2 months later. On Apr. 4, 1985 she was able to return to work, receiving UFTM-O therapy for one year as an outpatient. When ascites appeared in October, UFTM-O was discontinued and a single intraperitoneal administration of cis-platinum was done for peritoneal effusion. Another combination chemotherapy consisting of MTX, 5-FU and OK-432 was started, but she died 3 months later. In consequence, she had been able to live 18 months from the initial diagnosis. Moreover, she was able to enjoy a high quality of life, which meant she was able to return to her work and travel abroad, during the initial two-thirds of the disease period.

A combination of cefmenoxime (CMX) and cefsulodin (CFS) which has a broad spectrum on various bacteria including Pseudomonas aeruginosa was evaluated for severe infections associated with hematological malignancies. Seventy one patients were treated with the combination therapy. Among them, 57 patients were evaluable for the effectiveness. Fourteen patients were not evaluable because 10 patients were subjected to additional therapy such as gamma-globulin, interferon, radiation and pulse therapy of a large dose of methylprednisolone, 3 were prophylactically treated and the remaining one was a patient with disseminated bone marrow metastasis of prostatic cancer and not a patient with a hematologic malignancy. Excellent responses were obtained in 24 (42.1%) patients and good response in 12 (21.1%) patients, with a total rate of effectiveness of 63.2%. Three patients who were treated prophylactically and one patient who suffered from prostatic cancer with metastasis to bone marrow, were included in the final evaluation of side effects. Side effects were observed in only one patient (1/61, 1.6%). Mild neutropenia was identified in a patient of 78 years of age in 4 days after the combined regimen was started. Neutropenia disappeared soon after the cessation of the treatment. These results showed that a combination of CMX and CFS was an effective and safe regimen for the treatment of severe infections in patients with hematological disorders.

Rearrangement of the breakpoint cluster region (bcr) and the chromosomal location of c-abl and 3'-bcr were studied in two patients with Philadelphia chromosome (Ph1)-negative chronic myelocytic leukemia (CML). One patient (patient 1) had a normal karyotype and the other (patient 2), 46,XY,inv(3)(q21q26). Both patients showed the bcr rearrangement by Southern blot analysis with a 1.2kb 3'-bcr probe. In situ hybridization studies demonstrated the location of the homologous sequences of bcr on chromosome 22 in patient 1, and on chromosomes 9 and 22 in patient 2. These findings indicate that the morphologically normal-looking chromosomes 9 and 22 in patient 2 are the result of a retranslocation between chromosomes 9q+ and 22q-, abnormalities which were first formed by a standard Ph1 translocation.

We analyzed, by Southern blot hybridization, the site of breakpoint within the breakpoint cluster region (bcr) in six patients with a complex Philadelphia chromosome (Ph) translocation and in 23 unselected patients with a standard Ph. The breakpoint was found within the 5.8 kb bcr in all 29 patients. When the bcr was subdivided into four parts, fragments I-IV, based on the restriction enzyme sites, among the six patients with a complex Ph, two had a breakpoint at fragment I, three at fragment II, and one at fragment III. This distribution of breakpoints in patients with a complex Ph did not differ significantly from that in patients with a standard Ph. A deletion of an allele within the bcr was found in three patients (50%) with a complex Ph and in three (13%) with a standard Ph. The internal bcr deletion may be more common in patients with a complex Ph.

A combination of aztreonam (AZT) and clindamycin (CLDM) was evaluated for severe infections associated with leukemia and related disorders. AZT is a monobactam antibiotic which has strong bactericidal effect against Gram-negative bacteria including Pseudomonas aeruginosa. CLDM which has strong antibacterial spectrum against Gram-positive and anaerobic bacteria, was chosen as a partner of AZT in order to complement the weak points of AZT. Fifty six patients were treated with the combination therapy. Among them, 51 patients were evaluable for the effectiveness. Five patients were excluded from the evaluation because 3 patients were subjected to additional therapy with other agents such as amikacin, miconazole and pulse therapy of a large dose of methylprednisolone, one had a fever episode apparently due to primary disease, and the remaining one was discontinued of the combination therapy of administration due to mild nausea after 3 days. Excellent responses were obtained in 17 (33.3%) patients and good responses in 20 (39.2%) patients, with a total rate of effectiveness of 72.5%. One patient with whom the combination therapy was stopped due to nausea, was included in the final evaluation of side effects. Side effects were observed in 2 patients of 50 and 40 years of ages (2/52, 3.8%), both of whom suffered with nausea. In the 50 years patient of acute myeloblastic leukemia, nausea occurred in a slight degree in 3 hours after the combined regimen was started. But, it disappeared during the continuation of the combination therapy. In the 40 years patient of acute myelomonocytic leukemia, mild nausea occurred after 3 day administration of the combined regimen. It disappeared soon after the cessation of the treatment. These results indicated that a combination of AZT and CLDM was an effective and safe regimen for the treatment of severe infections in patients with hematological disorders.

A total of 10 episodes in 7 patients with leukemia or related disorders was treated with oral amphotericin B (AMPH). In 8 episodes AMPH were used prophylactically for severe neutropenia, and in the remaining 2 it was given when the patients were feverish. A daily dose of 2,400 mg of AMPH was given orally once a day and serum concentrations of AMPH were determined serially with bioassay. Two hours after administration, the mean serum concentration of AMPH rose to 0.15 microgram/ml, and reached 0.27 microgram/ml after 24 hours. The concentration was maintained between 0.23 microgram/ml and 0.39 microgram/ml through the following 7 days. These concentrations exceed the minimal inhibitory concentrations of most strains of Candida albicans. In 8 occasions of prophylactic use, no fungal infection was encountered. In a patient with pneumonia, chest X-ray and physical findings improved with administration of oral AMPH. Side effect of AMPH was seen in 1 patient, which was mild proteinuria and was eased rapidly after the withdrawal of AMPH. Clinical laboratory tests showed 1 case of proteinuria and disorder of kidney but did not clear under influence of AMPH. These results suggest that oral administration of AMPH is clinically and therapeutically effective and relatively safe for the prophylaxis or the treatment of fungal infection in patients with leukemia or related disorders.

The efficacy and the safety of a combination regimen using cefbuperazone (CBPZ) and amikacin (AMK) were evaluated in severe infections in patients with hematological diseases. Twenty two patients were subjected to this combination therapy; among these, 18 patients were evaluable for the effectiveness. They included 9 cases of leukemia, 5 cases of malignant lymphoma, 2 cases of aplastic anemia, and 2 cases of angio-immunoblastic lymphadenopathy with dysproteinemia. Excellent responses were obtained in 5 patients and good responses in 5 patients, with a total effectiveness of 55.6%. Efficacy rates for individual types of infections were; 2/2 in sepsis, 6/14, or 42.9% in suspected sepsis, 1/1 in urinary tract infection, and and 1/1 in upper respiratory infection. The combination treatment was also effective in 4 of 6 cases in which neutrophil counts were less than 500/mm3 prior to therapy. Side effects were observed in only one patient. Mild proteinuria occurred in a 80-year-old male in 6 days after the regimen was started, but was not serious. These results indicate that a combination of CBPZ and AMK is safe and effective for the treatment of infections even in patients with compromised immunodefenses.

A 44-year-old Japanese male having refractory anemia with excess of blasts (RAEB) preceding acute myelomonocytic leukemia (AMMoL) with dysplastic marrow eosinophilia (M4Eo in the FAB classification) is reported. Sequential cytogenetic studies revealed a specific chromosomal abnormality, inv(16) (p13q22), when RAEB was first diagnosed and again when overt leukemic transformation compatible with M4Eo was manifested. However, during the interval between the RAEB and AMMoL, an unrelated abnormal karyotype without inv(16), 47,XY,+9, was seen, when hematological data revealed remission after a low dose of cytosine arabinoside was administered. In this patient eosinophils in the marrow were involved in the leukemic process cytogenetically, because a few metaphases overlaid with eosinophilic granules had the inv(16) with other numerical abnormalities.

Forty one patients with infections associated with leukemia and related disorders were treated with cefpiramide (CPM). In 26 patients among them, we were able to evaluate the effectiveness of CPM against infections. Fifteen patients were not evaluated, because 6 patients were subjected to additional therapy such as gamma-globulin and other antibiotics, 5 were prophylactically treated, 2 had fever episode which were retrospectively reviewed to be originated from tumor mass, 1 received too short a duration of administration of CPM (2 days) to evaluate its effectiveness, and 1 with whom no precise data were recorded. Excellent responses were observed in 10 patients (38.5%) and good responses in 6 (23.1%) among these 26, with a total efficacy rate of 61.5%. Whereas, we found only one patient who showed an unfavorable side effect out of 31 patients including the 26 and 5 other patients who were prophylactically treated. The side effect observed was a mild bleeding tendency occurred in 77 years old female at 11 days after CPM was administrated. The bleeding tendency was easily diminished with the cessation of CPM treatment and a parenteral use of vitamin K. These results suggest that CPM is an effective and safe antibiotic for the treatment of infections in patients with leukemia and related disorders.

We have studied in-vitro growth of leukemic progenitor cells (L-CFU) in ten patients with acute promyelocytic leukemia (APL). All patients showed consistently an extraordinarily high incidence of cluster formation under the stimulation of human placental conditioned medium (HPCM) and/or phytohemagglutinin-stimulated leukocyte conditioned medium (PHA-LCM). Cytogenetic analyses of clusters or colonies disclosed the presence of a 15;17 translocation. These findings may represent the close relationship between specific chromosomal aberration, t(15;17), and the growth pattern of L-CFU of APL in vitro.

A modified short-term culture method, in which cultured bone marrow cells were treated with ethidium bromide to prevent chromosome condensation was used to study the chromosomes of 70 patients with acute nonlymphocytic leukemia. Clonal karyotypic abnormalities were detected in 60 patients. Among these, 35 patients showed one of recurrent type specific alterations. A close relationship between karyotypes and clinical outcome was shown: thus, t(8;21) or a single miscellaneous chromosomal defect associated with a favourable prognosis whereas t(9;11) or a complex karyotype related to a poor prognosis. The ten cytogenetically normal patients did not appear to have a favourable prognosis.