Including Cytosine Arabinoside Research Articles

Recent and remote spatial memory in mice treated with cytosine arabinoside

Clinical studies suggest that chemotherapy is associated with long-term cognitive impairment in some patients. A number of underlying mechanisms have been proposed, however, the etiology of chemotherapy-related cognitive dysfunction remains relatively unknown. As part of a multifaceted approach, animal models of chemotherapy-induced cognitive impairment are being developed. Thus far, the majority of animal studies have utilized a rat model, however, mice may prove particularly beneficial in studying genetic risk factors for developing chemotherapy-induced cognitive impairment. Various chemotherapy agents, including cytosine arabinoside (Ara-C), have been found to impair remote spatial memory in rats in the Morris water maze. The present study evaluated the effects of Ara-C on remote (30d) spatial memory in mice. In addition, the possibility that time relative to chemotherapy treatment may modulate the effect of chemotherapy on spatial learning and/or recent (1d) memory was explored. Male C57BL/6J mice received either Ara-C (275mg/kgi.p. daily for 5days) or saline. Spatial learning and memory was assessed using the Morris water maze. Half the mice performed a remote (30d) memory version of the task and the other half performed a recent (1d) memory version of the task. The experiment was designed such that the probe trial for the recent memory version occurred on the same day relative to chemotherapy treatment as the remote memory version. Despite significant toxic effects as assessed by weight loss, Ara-C treated mice performed as well as control mice during acquisition, recent memory, and remote memory portions of the task. As are some humans, C57BL/6J mice may be resistant to at least some aspects of chemotherapy induced cognitive decline.

Sustained recovery of progressive multifocal leukoencephalopathy after treatment with IL-2

Currently, most patients diagnosed with progressive multifocal leukoencephalopathy (PML) are infected with HIV; highly active antiretroviral therapy (HAART) has prolonged the median survival of these patients from 3 months to 1 year.1 Despite encouraging initial case reports, other therapies, including cytosine arabinoside and alpha INF, have been disappointing for both HIV and non-HIV patients with PML.2–4 In addition to the lack of convincing evidence that these treatments alter the natural course of PML, there are concerns of toxicity in patients with low blood counts. Because a plausible biologic basis exists for a role for recombinant interleukin-2 (rIL-2) in the reconstitution of impaired antiviral immune functions, this immunotherapy was administered previously in a patient with PML with apparent success.5 Based on this report, we chose rIL-2 as initial therapy for a patient with myelodysplasia who developed PML. A 58-year-old woman with a 20-year history of myelodysplastic syndrome presented in March 2000 with dysarthria and right hand clumsiness, which developed …

Viridans Streptococcus Bacteremia in Children on Chemotherapy for Cancer: An Underestimated Problem

The authors discuss the morbidity associated with viridans streptococcus bacteremia, and its implications on the choice of antibiotics used as prophylaxis and treatment. They retrospectively studied the case notes of 38 children who were being treated for various malignant conditions in their unit and developed 40 episodes of bacteremia with viridans streptococci between October 1995 and January 1999. Viridans streptococci were the third commonest blood culture isolate during this period, after coagulase-negative staphylococci and Staphylococcus aureus . The majority of the isolates were Streptococcus mitis (55%). Others were S. sanguis (25%), S. oralis (12.5%), S. salivarius (5%), and S. acidominimus (2.5%). Twenty-five percent of the patients had been treated with regimens that included cytosine arabinoside, 60% were receiving prophylactic co-trimoxazole, and 87.5% were neutropenic. Thirty percent of patients had abnormal chest X-rays, and 15% were hypotensive; 2 patients required admission to the intensive care unit. Initial antibiotic therapy was changed because of failure of clinical response in 60% of cases, despite the infecting organism being sensitive in vitro. This study confirms the importance of viridans streptococci as a cause of bacteremia in pediatric hematology and oncology patients, leading to significant morbidity. Further work is required to establish the optimal treatment for viridans streptococcus bacteremia.

Viridans Streptococcus Bacteremia in Children on Chemotherapy for Cancer: An Underestimated Problem

The authors discuss the morbidity associated with viridans streptococcus bacteremia, and its implications on the choice of antibiotics used as prophylaxis and treatment. They retrospectively studied the case notes of 38 children who were being treated for various malignant conditions in their unit and developed 40 episodes of bacteremia with viridans streptococci between October 1995 and January 1999. Viridans streptococci were the third commonest blood culture isolate during this period, after coagulase-negative staphylococci and Staphylococcus aureus . The majority of the isolates were Streptococcus mitis (55%). Others were S. sanguis (25%), S. oralis (12.5%), S. salivarius (5%), and S. acidominimus (2.5%). Twenty-five percent of the patients had been treated with regimens that included cytosine arabinoside, 60% were receiving prophylactic co-trimoxazole, and 87.5% were neutropenic. Thirty percent of patients had abnormal chest X-rays, and 15% were hypotensive; 2 patients required admission to the intensive care unit. Initial antibiotic therapy was changed because of failure of clinical response in 60% of cases, despite the infecting organism being sensitive in vitro. This study confirms the importance of viridans streptococci as a cause of bacteremia in pediatric hematology and oncology patients, leading to significant morbidity. Further work is required to establish the optimal treatment for viridans streptococcus bacteremia.

Adenosine prevents the death of mesencephalic dopaminergic neurons by a mechanism that involves astrocytes.

The purinergic nucleoside adenosine effectively prevented the death of dopaminergic neurons that occurs spontaneously and progressively in cultures of rat mesencephalon. Adenosine also significantly increased dopamine uptake, attesting to the state of differentiation and functional integrity of the neurons that were rescued. The effects of adenosine were (a) specific to the dopaminergic neurons in these cultures, (b) long-lived, (c) still observed when the treatment was delayed after plating, (d) potentiated by inhibition of adenosine deaminase, and (e) abolished when this enzyme was added in excess to the culture medium. The action of adenosine was mimicked by 5'-(N-ethylcarboxamido)adenosine and dibutyryl-cyclic AMP, but not by CGS-21680, suggesting the possible involvement of A2B subtype purinergic receptors. ATP was also neuroprotective, but its action resulted principally from conversion to adenosine by ectonucleotidases. Several anticancer drugs, including cytosine arabinoside, have been shown previously to prevent apoptosis in cultured dopaminergic neurons by a mechanism that requires the inhibition of proliferating astrocytes. In the presence of adenosine, astrocytes were more differentiated, and their proliferation rate was significantly reduced, suggesting that the neurotrophic effect of the adenine nucleoside resulted also from the repression of the astroglial cells. We did not find evidence of a trophic intermediary in adenosine-treated cultures, however, leading to the hypothesis that limitation of astrocyte replication in itself and/or ensuing changes in the glial phenotype were crucial. Our results suggest that molecules that modulate adenine nucleotide/nucleoside release may be useful for the treatment of chronic neurodegenerative conditions affecting dopaminergic neurons, such as Parkinson's disease.

Autologous transplantation of chemotherapy-purged PBSC collections from high-risk leukemia patients: a pilot study.

We have recently demonstrated that the combination of the alkylating agent nitrogen mustard (NM) and etoposide (VP-16) is capable of eliminating, ex vivo, leukemic cells contaminating PBSC collections and this is associated with a significant recovery of primitive and committed hematopoietic progenitor cells. Based on these data a pilot study on autologous transplantation of NM/VP-16 purged PBSC for high-risk leukemic patients was recently initiated. Twelve patients (seven females and five males) with a median age of 46 years (range 18-57) have been treated. Two patients had acute myeloblastic leukemia (AML) resistant to conventional induction treatment, four patients had secondary AML in I complete remission (CR), one patient was in II CR after failing a previous autologous BM transplantation, while two additional AML individuals were in I CR achieved after three or more cycles of induction treatment. Two patients with high-risk acute lymphoblastic leukemia (ALL) in I CR and one patient with mantle cell lymphoma and leukemic dissemination were also included. Eight patients showed karyotypic abnormalities associated with a poor clinical outcome. The mobilizing regimens included cytosine arabinoside and mitoxantrone with (n = 6) or without fludarabine (n = 3) followed by subcutaneous administration of G-CSF (5 microg/kg/day until the completion of PBSC collection) and G-CSF alone (n = 3) (15 microg/kg/day). A median of two aphereses (range 1-3) allowed the collection of 7.2 x 10(8) TNC/kg (range 3.4-11.5), 5 x 10(6) CD34+ cells/kg (range 2.1-15.3) and 9.2 x 10(4) CFU-GM/kg (0.3-236). PBSC were treated with a constant dose of 20 microg of VP-16/ml and a median individual-adjusted dose (survival < or = 5% of steady-state BM CFU-GM) of NM of 0.7 microg/ml (range 0.25-1.25). Eleven patients were reinfused after busulfan (16 mg/kg) and Cy (120 mg/kg) conditioning with a median residual dose of 0.3 x 10(4) CFU-GM/kg (0-11.5). The median time to neutrophil engraftment (>0.5 x 10(9)/l) for evaluable patients was 25 days (range 12-59); the median time to platelet transfusion independence (>20 and >50 x 10(9)/l) was 40 days (18-95) and 69 days (29-235), respectively. Hospital discharge occurred at a median of 25 days (18-58) after stem cell reinfusion. Four individuals are alive in CR (n = 3) or with residual nodal disease (n = 1 lymphoma patient) with a follow-up of 32, 26, 3 and 14 months, respectively. Seven patients died due to disease progression or relapse (n = 5) or extrahematological transplant toxicity (n = 2). Our data suggest that pharmacological purging of leukapheresis collections of leukemic patients at high-risk of relapse is feasible and ex vivo treated cells reconstitute autologous hematopoiesis.

An Escherichia coli system expressing human deoxyribonucleoside salvage enzymes for evaluation of potential antiproliferative nucleoside analogs.

Deoxyribonucleoside salvage in animal cells is mainly dependent on two cytosolic enzymes, thymidine kinase (TK1) and deoxycytidine kinase (dCK), while Escherichia coli expresses only one type of deoxynucleoside kinase, i.e., TK. A bacterial whole-cell system based on genetically modified E. coli was developed in which the relevant bacterial deoxypyrimidine metabolic enzymes were mutated, and the cDNA for human dCK or TK1 under the control of the lac promoter was introduced. The TK level in extract from induced bacteria with cDNA for human TK1 was found to be 20,000-fold higher than that in the parental strain, and for the strain with human dCK, the enzyme activity was 160-fold higher. The in vivo incorporation of deoxythymidine (Thd) and deoxycytidine (dCyd) into bacterial DNA by the two recombinant strains was 20 and 40 times higher, respectively, than that of the parental cells. A number of nucleoside analogs, including cytosine arabinoside, 5-fluoro-dCyd, difluoro-dCyd, and several 5-halogenated deoxyuridine analogs, were tested with the bacterial system, as well as with human T-lymphoblast CEM cells. The results showed a close correlation between the inhibitory effects of several important cytostatic and antiviral analogs on the recombinant bacteria and the cellular system. Thus, E. coli expressing human salvage kinases is a rapid and convenient model system which may complement other screening methods in drug discovery projects.

Penicillin-Resistant Streptococcus mitis as a Cause of Septicemia with Meningitis in Febrile Neutropenic Children

The purpose of this report is to emphasize the importance of occurrence of Streptococcus mitis meningitis in febrile neutropenic children with hematopoietic malignancy. Symptoms of meningitis and sepsis (fever, headache, changes in mental status) were seen in three patients who were severely neutropenic and undergoing cytotoxic chemotherapy for CNS relapse of their underlying malignancy (acute lymphoblastic leukemia (ALL), n = 2; Burkitt's lymphoma, n = 1). Chemotherapy had included cytosine arabinoside administered 7-14 days prior to presenting with sepsis and meningitis. All three patients had buccal mucositis or sinusitis. Blood cultures and CSF cultures showed S. mitis resistant to penicillin but sensitive to vancomycin. Vancomycin, at a dosage of 60 mg/kg/day to maximize CNS levels of antibiotic, was administered to all three children. Two of the patients recovered from S. mitis meningitis; recovery was associated with an improvement in their peripheral granulocyte counts. One patient, who remained neutropenic, died despite being treated with both intravenous and intraventricular vancomycin. Physicians caring for patients who are neutropenic and febrile need to be aware of the risk of meningitis occurring with S. mitis sepsis. Early treatment with high dosages of vancomycin (60 mg/kg/day) and an attempt to limit the duration of neutropenia are important factors in the outcome of such patients.

Drug-induced pulmonary alveolar disease

A variety of alveolar diseases can be caused by several drugs. The most important diseases, and the drugs that cause them, are— non-cardloçenlc pulmonary oedema: naloxone, intravenous beta2-agonisls, hydrochlorothiazide, desfernoxamine, and more rarely other agents including cytosine arabinoside, carbamazepine, cyclosporin, and haloperidol; Interstitial pneumonltis and lung fibrosis: gold, amiodarone, methotrexate, nitrofurantoin, busulphan, bleomycin, cyclophosphamide, nitrosoureas, sulphasalazine, and, rarely, beta-adrenoceptor blockers: pulmonary eosinophilic: sulphonamides, penicillin, tetracyclines, non-steroidal antiinflammatory drugs, and aminosalicyiates; organizing pneumonia: gold, amiodarone, penicillamine, bleomycin, and sulphasalazine; drug-induced lupus disease: hydralazine, procainamide, sulphasalazine, alphamethyldopa, isoniazid, and phenytoin. pulmonary haemorrhage: poorly controlled anticoagulant therapy and penicillamine therapy.

Unrelated Bone Marrow Donor Transplants for Children With Leukemia or Myelodysplasia

Allogeneic bone marrow transplantation is the treatment of choice for many childhood leukemias. The donor of choice-an HLA matched sibling-is only available about 30% of the time. Unrelated donors are an alternative choice. In this report, we describe the results of unrelated donor bone marrow transplants (BMT) in 50 children with leukemia (25 acute lymphoblastic leukemia [ALL], 3 acute myeloid leukemia [AML], 3 juvenile chronic myelogenous leukemia [JCML], 10 chronic myeloid leukemia [CML]) or myelodysplastic syndrome (MDS; 9). The median age of the 31 male and 19 female patients was 9 years (range 2 to 18). Only 13 patients were serologically matched at HLA-A, B, DR, and DQ with their donors; 6 of these were reactive in mixed lymphocyte culture. The other 37 patients were mismatched for one (36 patients) or more (1 patient) HLA antigens. Pretransplant conditioning included cytosine arabinoside, cyclophosphamide, fractionated total body irradiation (TBI) (with lung, liver, and more recently, kidney shielding), and methylprednisolone. High-risk patients also received busulfan. Graft-versus-host disease (GVHD) prophylaxis consisted of T-cell depletion with IgM monoclonal antibody T10B9 plus complement and posttransplant cyclosporine-A. Forty-nine patients (98%) engrafted. Median times to greater than 500 polymorphonuclear leukocytes (PMN)/microL and greater than 25,000 platelets/microL were 18 and 20 days, respectively. Acute GVHD > or = grade II occurred in 16 patients (33%); 13 (81%) of these died. Chronic GVHD developed in 30 of 40 patients at risk, but was extensive in only 5. Event-free survival (EFS) for all patients was 44% +/- 7% (median follow-up was 49 months), and overall survival was 50 +/- 7%. Patients with low-risk disease (ALL or AML in first or second remission and CML in chronic phase) had a better EFS than children with high-risk disease (60% v 34%, P = .07). There was no significant difference in EFS between patients who were serologically matched with their donors (46%) and those who were partially mismatched (43%) (P = .97). These data compare favorably with published reports for children transplanted with HLA-matched sibling donors and should encourage earlier consideration of unrelated donor BMT in children with leukemia or myelodysplasia.

High-Dose Cyclophosphamide-High-Dose Methotrexate with Coordinated Intrathecal Therapy for Advanced Nonlymphoblastic Lymphoma of Childhood

The Pediatric Oncology Group (POG) investigated a high-dose cyclophosphamide (CPM) high-dose methotrexate (MTX) regimen to determine therapeutic efficacy in confirmed advanced nonlymphoblastic non-Hodgkin's lymphoma (NHL) (stages III and IV) and B-cell acute lymphatic leukemia (B-ALL) in children. Another goal was to determine the comparative effectiveness of shortened maintenance treatment (2 versus 6 courses) in the study population. Systemic induction therapy included vincristine, prednisone, cyclophosphamide, and intermediate-dose MTX with leucovorin rescue. Superimposed intrathecal (IT) therapy included cytosine arabinoside for 2 successive days followed on day 3 by MTX. Intrathecal MTX was given 3 times during induction. At the end of induction, 2 days of triple (hydrocortisone, MTX, and cytosine arabinoside) therapy were given intrathecally (TIT). All patients then received a consolidation course of 4 doses of TIT, 2 doses of cyclophosphamide, and 4 more courses of vincristine and MTX with leucovorin rescue. Patients were then randomized to receive either 2 or 6 cycles of vincristine plus MTX with leucovorin rescue. The TIT was given with each cycle. Complete response rates by histology and Murphy stage (1) were as follows: undifferentiated lymphoma (DUL) stage III, 84/105 (80%): stage IV, 5/12 (42%); and other NHL [primarily large cell lymphoma (LCL)] stage III, 21/28 (75%); stage IV, 2/3 (67%). Event-free survival (EFS) at greater than 2 years was similar for patients with DUL and LCL, i.e., 65 and 61%, respectively. No significant difference in outcome was noted between patient groups receiving 2 or 6 maintenance treatments (p = .76). Treatment was notable for its modest toxicity following the early change to single-dose CPM therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Chromosomes, Auer rods and prognosis in acute myeloid leukaemia.

We have analysed survival time and complete remission (CR) rate after induction treatment including cytosine arabinoside and an anthracycline antibiotic in 94 patients with acute myeloid leukaemia, comparing the results in four different groups according to the presence or absence of Auer rods and the presence (AN/AA) or absence (NN) of abnormal cytogenetic clones at diagnosis. The finding of Auer rods was a positive prognostic factor with respect to CR rate (p less than 0.02) and survival time (p less than 0.02) irrespective of the cytogenetic pattern. The AN/AA pattern was associated with lower CR rate (p less than 0.05) and 6-months survival (p = 0.05) in the 49 Auer rod-negative patients. In the 45 patients with Auer rods, no significant differences in CR rate or survival were seen between AN/AA and NN patients. We conclude that the negative prognostic impact of chromosome abnormalities in acute myeloid leukaemia might be restricted to Auer rod-negative disease.

Stem cell apheresis in patients with acute nonlymphocytic leukemia

In patients with acute nonlymphocytic leukemia (ANLL) it has previously been reported that the number of blood-derived hemopoietic stem cells (HSC) is very low during the remission phase. 1,2 However, we and others have recently demonstrated that the concentration of granulocyte-macrophage precursors (CFU-GM cells) in the peripheral blood could be increased to 10- to 40-fold above the mean value in normal subjects during the period of marrow reconstitution following aplasia (or hypoplasia) induced by previous chemotherapy. 1,3 To collect high numbers of circulating HSC, leukocyta-phereses could be performed during this short period of “recirculation” of blood-derived progenitors. However, patients with ANLL may be subjected to different chemotherapy regimens that vary according to the age of the patients, the status of the leukemia, and the therapeutic strategy. The amplitude of the recirculation of CFU-GM cells during remission is influenced mostly by the type of chemotherapy administered to the patient. 1 In order to evaluate this phenomenon, we serially assayed peripheral blood CFU-CM cells in 26 ANLL patients. The mean value of the highest recorded peak (HRP) level was 4370 CFU-GM/mL (1133 to 9066) in 13 patients who achieved complete remission after a single course of induction treatment including cytosine arabinoside (Ara-c) (100 mg/m2 × 10 days) and daunorubicin (DNR) (60 mg/m2 × 3 days). As mentioned in a previous report, HPR levels of CFU-GM cells observed in two patients given a late, intensification treatment (with DNR: 300 mg/m2) were similar to those observed in these latter 13 patients. 1 The recirculation of CFU-GM cells was less marked in seven patients who received two consecutive courses of induction chemotherapy or in four other patients receiving less intensive treatment as consolidation. 1,2 These results confirm the results of our previous report and the data reported by To et al., who studied 13 ANLL patients during the very early remission phase following induction chemotherapy. 3 They found that the mean value of the HRP level of CFU-GM cells was 2796/mL (370 to 14520) and concluded that the early remission period after one single course of chemotherapy could be the best time for collection of circulating HSC in ANLL patients.

Cytotoxicity of antineoplastic agents on rabbit corneal epithelium in vitro

AbstractWe studied the cytotoxic effects of antineoplastic agents in vitro including cytosine arabinoside (Ara-C), methotrexate, melphalan, 5-fluorouracil (5-FU), and triethylenethiophosphoramide (thiotepa), using rabbit corneal epithelial cell primary tissue cultures. Twenty-four hour [3H]thymidine incorporation was measured 6 hr after the addition of drug or vehicle. A dose-response effect was noted for all agents. Significant (p <0.05) inhibition of thymidine incorporation was reached with Ara-C (10−7M), methotrexate (10−3M), melphalan (10-6M), 5-FU (10−4M), and thiotepa (10−4M). Visual inspection of the cultures was a less sensitive indicator of drug-induced cytotoxicity; except for melphalan, drug concentrations much greater than those that inhibited thymidine incorporation did not alter cell morphology. At a concentration of 10−4M, 2′-deoxycytidine, a competitive inhibitor of Ara-C, protected corneal epithelial cells exposed to Ara-C concentrations up to 10−5M. When used alone, concentrations of deo...

3-Deazauridine (NSC 126849): an interesting modulator of biochemical response

3-Deazauridine (NSC 126849) is a structural analog of uridine that inhibits the biosynthesis of Cytidine-5'-Triphosphate by competitive inhibition of Cytidine Triphosphate synthetase which is considered to be the primary mode of action of this nucleoside analog. Despite a paucity of clinical attention given to this drug as a single agent, it has generated much enthusiasm as a biological response modulator because of its synergistic effect with a number of antitumor agents including Cytosine Arabinoside, 5-aza-2'-deoxycytidine, 5-azacytidine, thymidine and D-galactosamine, although only the cytosine arabinoside/3-Deazauridine combination has been explored clinically. In this paper, the current status of the drug and future perspectives will be discussed.

Circulating myeloid progenitor cells in patients with aml after induction chemotherapy

In patients with acute nonlymphocytic leukemia (ANLL) it has previously been reported that the number of blood-derived hemopoietic stem cells (HSC) is very low during the remission phase.1,2 However, we and others have recently demonstrated that the concentration of granulocyte-macrophage precursors (CFU-GM cells) in the peripheral blood could be increased to 10- to 40-fold above the mean value in normal subjects during the period of marrow reconstitution following aplasia (or hypoplasia) induced by previous chemotherapy.1,3 To collect high numbers of circulating HSC, leukocyta-phereses could be performed during this short period of “recirculation” of blood-derived progenitors.However, patients with ANLL may be subjected to different chemotherapy regimens that vary according to the age of the patients, the status of the leukemia, and the therapeutic strategy. The amplitude of the recirculation of CFU-GM cells during remission is influenced mostly by the type of chemotherapy administered to the patient.1 In order to evaluate this phenomenon, we serially assayed peripheral blood CFU-CM cells in 26 ANLL patients. The mean value of the highest recorded peak (HRP) level was 4370 CFU-GM/mL (1133 to 9066) in 13 patients who achieved complete remission after a single course of induction treatment including cytosine arabinoside (Ara-c) (100 mg/m2 × 10 days) and daunorubicin (DNR) (60 mg/m2 × 3 days). As mentioned in a previous report, HPR levels of CFU-GM cells observed in two patients given a late, intensification treatment (with DNR: 300 mg/m2) were similar to those observed in these latter 13 patients.1 The recirculation of CFU-GM cells was less marked in seven patients who received two consecutive courses of induction chemotherapy or in four other patients receiving less intensive treatment as consolidation.1,2 These results confirm the results of our previous report and the data reported by To et al., who studied 13 ANLL patients during the very early remission phase following induction chemotherapy.3 They found that the mean value of the HRP level of CFU-GM cells was 2796/mL (370 to 14520) and concluded that the early remission period after one single course of chemotherapy could be the best time for collection of circulating HSC in ANLL patients.

Acute promyelocytic leukemia in 57 previously untreated patients.

Fifty-seven patients in initial phase of acute promyelocytic leukemia (APL) were treated in the same department with heparin infusion, platelet transfusions, and two related induction regimens both including cytosine arabinoside and daunorubicin. Clinical and biological findings at presentation were studied. The complete remission (CR) rate was 53%. Twenty-seven patients (47%) died during the initial course of the disease, either before day 5 (early death [ED], n = 7) or after day 5 (death in aplasia [DA], n = 20). Most ED was due to intracerebral hemorrhage (6/7), especially when large hemorrhages had been seen on fundus oculi examination. Most DA was due to multivisceral failure (9/20). No correlation was found between initial disseminated intravascular coagulation (DIC) and death. However, the worsening of coagulation parameters during induction therapy, with or without initial DIC, significantly increased the occurrence of renal and respiratory failure which were particularly frequent during the first month. The median duration of survival was short (3.5 months) and the median duration of CR (11 months) was similar to that of other acute myeloid leukemias treated with the same regimens. The possible causes of the high mortality observed during the initial courses of APL and the possible benefit of a more graduate induction chemotherapy are discussed.

Characterization of IM virus, which is frequently isolated from cerebrospinal fluid of patients with multiple sclerosis and other chronic diseases of the central nervous system.

A transmissible agent, the IM virus, antigenically related to the Japanese subacute myelo-optico-neuropathy virus, has been isolated from several human cerebrospinal fluids obtained from American patients with multiple sclerosis and other chronic diseases of the central nervous system. The isolates were propagated in human diploid fibroblast (MRC5) cells, and virus was released into the culture medium in the absence of overt cytolysis. Infection of MRC5 cells resulted in a subtle alteration in the normal growth pattern of the cells. In unstained cultures, the cell changes were so mild that it was necessary to carry out all virus assays under code to eliminate bias. Cells in late passages were more susceptible than vigorously growing cells in early passages. Analysis of the kinetics of replication revealed that newly synthesized progeny virus was first detected about 12 h postinfection, that maximal virus release occurred by 48 h postinfection, and that virus production was persistent throughout an 8-day period. Several inhibitors of DNA synthesis were effective in blocking viral replication, including cytosine arabinoside, iododeoxyuridine, and phosphonoacetic acid. A substantial decrease in infectivity was observed upon treatment of IM virus with ether, suggesting that a lipid-containing structure is essential for infectivity. Ultrafiltration studies approximated the size (diameter) of IM virus to be between 100 and 200 nm.

Isolation and culture of the terminally differentiated adult mammalian ventricular cardiac muscle cell.

We have carried out systematic studies to optimize and standardize methodology to isolate and culture the adult rat ventricular cardiac muscle cell. Four hearts were perfused simultaneously with a calcium-free medium containing collagenase. The ventricular tissue was then minced and further digested to liberate individual cells. Approximately 16 million rod-shaped muscle cells were obtained. The plating efficiency has been greatly improved by culturing the cells in a conditioned medium prepared from a rabbit corneal cell line. This medium also contained added fetal bovine serum, essential and nonessential amino acids, vitamins, insulin, transferrin, and 25 trace minerals. The culture flasks were precoated with rat-tail collagen. Fibroblast contamination was virtually eliminated by including cytosine arabinoside in the medium during the first 7 d of culture. After this time the cells could be cultured in the absence of serum in a chemically defined medium composed of MEM, vitamins, nonessential amino acids, and trace minerals. They continued to contract spontaneously and do well in this medium for at least 3 d thereafter. This improved methodology resulted in a reproducible culture system with improved plating efficiency. It provided a new and unique system to study the structure and function of the adult mammalian ventricular cardiac muscle cell.

Evaluation of cyclocytidine in reinduction and maintenance therapy of children with acute nonlymphocytic leukemia previously treated with cytosine arabinoside: A report from children's cancer study group

A study of children in relapse with acute nonlymphocytic leukemia (ANLL) previously maintained in remission with combination chemotherapy including cytosine arabinoside (Ara-C) was undertaken by Children's Cancer Study Group (CCSG) to assess the efficacy of cyclocytidine (Cyclo-C), a depot Ara-C, compared to parenteral Ara-C given every 12 hr. The reinduction protocol consisted of daunomycin combined with either Ara-C (Regimen 1) or Cyclo-C (Regimen 2). One-hundred thirty eligible patients were entered on the randomized study. Hematologic toxicity was significant in both regimens and resulted in four drug-related deaths. Cardiac toxicity was observed in five patients, manifested only by abnormal echocardiogram or electrocardiogram patterns in three and congestive heart failure in two patients. Seventy-seven of 112 evaluable patients achieved M-1 or M-2A marrow remissions (69%): 46 of 60 on Regimen 1 (75%), 30 of 52 on Regimen 2 (60%). The remission rate between the two regimens was not significantly different. There was no significant difference in the duration of remission comparing maintenance cyclophosphamide combined with Ara-C or with Cyclo-C. Addition of VP-16 and CCNU to the maintenance therapy did not prolong the duration of remission. This study indicates that patients with childhood ANLL previously treated with Ara-C and daunomycin can obtain a successful second remission. A single daily subcutaneous dose of Cyclo-C was found to be as efficacious as Ara-C given intravenously every 12 hr. The single dose schedule provides a convenient way to treat patients with relapsed ANLL in the outpatient setting.