User-defined outcomes of the Danish cardiovascular screening (DANCAVAS) trial: A post hoc analyses of a population-based, randomised controlled trial

BACKGROUND

The Danish cardiovascular screening (DANCAVAS) trial, a nationwide trial designed to investigate the impact of cardiovascular screening in men, did not decrease all-cause mortality, an outcome decided by the investigators. However, the target group may have varied preferences. In this study, we aimed to evaluate whether men aged 65 to 74 years requested a CT-based cardiovascular screening examination and to assess its impact on outcomes determined by their preferences.

METHODS AND FINDINGS

This is a post hoc study of the randomised DANCAVAS trial. All men 65 to 74 years of age residing in specific areas of Denmark were randomised (1:2) to invitation-to-screening (16,736 men, of which 10,471 underwent screening) or usual-care (29,790 men). The examination included among others a non-contrast CT scan (to assess the coronary artery calcium score and aortic aneurysms). Positive findings prompted preventive treatment with atorvastatin, aspirin, and surveillance/surgical evaluation. The usual-care group remained unaware of the trial and the assignments. The user-defined outcome was based on patient preferences and determined through a survey sent in January 2023 to a random sample of 9,095 men from the target group, with a 68.0% response rate (6,182 respondents). Safety outcomes included severe bleeding and mortality within 30 days after cardiovascular surgery. Analyses were performed on an intention-to-screen basis. Prevention of stroke and myocardial infarction was the primary motivation for participating in the screening examination. After a median follow-up of 6.4 years, 1,800 of 16,736 men (10.8%) in the invited-to-screening group and 3,420 of 29,790 (11.5%) in the usual-care group experienced an event (hazard ratio (HR), 0.93 (95% confidence interval (CI), 0.88 to 0.98; p = 0.010); number needed to invite at 6 years, 148 (95% CI, 80 to 986)). A total of 324 men (1.9%) in the invited-to-screening group and 491 (1.7%) in the usual-care group had an intracranial bleeding (HR, 1.17; 95% CI, 1.02 to 1.35; p = 0.029). Additionally, 994 (5.9%) in the invited-to-screening group and 1,722 (5.8%) in the usual-care group experienced severe gastrointestinal bleeding (HR, 1.02; 95% CI, 0.95 to 1.11; p = 0.583). No differences were found in mortality after cardiovascular surgery. The primary limitation of the study is that exclusive enrolment of men aged 65 to 74 renders the findings non-generalisable to women or men of other age groups.

CONCLUSION

In this comprehensive population-based cardiovascular screening and intervention program, we observed a reduction in the user-defined outcome, stroke and myocardial infarction, but entail a small increased risk of intracranial bleeding.

TRIAL REGISTRATION

ISRCTN Registry number, ISRCTN12157806 https://www.isrctn.com/ISRCTN12157806.

Association of Left Atrial Size Measured by Non-Contrast Computed Tomography with Cardiovascular Risk Factors—The Danish Cardiovascular Screening Trial (DANCAVAS)

Left atrium (LA) size is associated with adverse cardiovascular events. The purpose of this study was to investigate the association of LA enlargement measured by non-contrast CT (NCCT) with traditional cardiovascular risk factors. Individuals aged 60–75 years from the population-based multicentre Danish Cardiovascular Screening (DANCAVAS) trial were included in this cross-sectional study. The LA was manually traced on the NCCT scans, and the largest cross-section area was indexed to body surface area. All traditional risk factors were recorded, and a subgroup received an echocardiographic examination. We enrolled 14,987 individuals. Participants with known cardiovascular disease or lacking measurements of LA size or body surface area were excluded, resulting in 10,902 men for the main analysis and 616 women for a sensitivity analysis. Adjusted multivariable analysis showed a significantly increased indexed LA size by increasing age and pulse pressure, while smoking, HbA1c, and total cholesterol were associated with decreased indexed LA size. The findings were confirmed in a supplementary analysis including left ventricle ejection fraction and mass. In this population-based cohort of elderly men, an association was found between age and pulse pressure and increasing LA size. Surprisingly, smoking, HbA1c, and total cholesterol were associated with a decrease in LA size. This indicates that the pathophysiology behind atrial cardiomyopathy is not only reflected by enlargement, but also shrinking.

Mitral Annulus Calcification and Cardiac Conduction Disturbances: a DANCAVAS Sub-study

BACKGROUND

Due to its location very close to the bundle of His, mitral annulus calcification (MAC) might be associated with the development of atrioventricular (AV) conduction disturbances. This study assessed the association between MAC and AV conduction disturbances identified by cardiac implantable electronic device (CIED) use and electrocardiographic parameters. The association between MAC and traditional cardiovascular risk factors was also assessed.

METHODS

This cross-sectional study analyzed 14,771 participants, predominantly men aged 60–75 years, from the population-based Danish Cardiovascular Screening trial. Traditional cardiovascular risk factors were obtained. Using cardiac non-contrast computed tomography imaging, MAC scores were measured using the Agatston method and divided into absent versus present and score categories. CIED implantation data were obtained from the Danish Pacemaker and Implantable Cardioverter Defibrillator Register. A 12-lead electrocardiogram was available for 2,107 participants. Associations between MAC scores and AV conduction disturbances were assessed using multivariate regression analyses.

RESULTS

MAC was present in 22.4% of the study subjects. Participants with pacemakers for an AV conduction disturbance had significantly higher MAC scores (odds ratio [OR], 1.11; 95% confidence interval [CI], 1.01–1.23) than participants without a CIED, whereas participants with a CIED for other reasons did not. Prolonged QRS-interval was significantly associated with the presence of MAC (OR, 1.45; 95% CI, 1.04–2.04), whereas prolonged PQ-interval was not. Female sex and most traditional cardiovascular risk factors were significantly associated with high MAC scores.

CONCLUSIONS

MAC was associated with AV conduction disturbances, which could improve our understanding of the development of AV conduction disturbances.

Cross-sectional study of aortic valve calcification and cardiovascular risk factors in older Danish men

OBJECTIVE

Aortic valve calcification (AVC) and coronary artery calcification (CAC) are predictors of cardiovascular disease (CVD), presumably sharing risk factors. Our objectives were to determine the prevalence and extent of AVC in a large population of men aged 60-74 years and to assess the association between AVC and cardiovascular risk factors including CAC and biomarkers.

METHODS

Participants from the DANish CArdioVAscular Screening and intervention trial (DANCAVAS) with AVC and CAC scores and without previous valve replacement were included in the study. Calcification scores were calculated on non-contrast CT scans. Cardiovascular risk factors were self-reported, measured or both, and further explored using descriptive and regression analysis for AVC association.

RESULTS

14 073 men aged 60-74 years were included. The AVC scores ranged from 0 to 9067 AU, with a median AVC of 6 AU (IQR 0-82). In 8156 individuals (58.0%), the AVC score was >0 and 215 (1.5%) had an AVC score ≥1200. In the regression analysis, all cardiovascular risk factors were associated with AVC; however, after inclusion of CAC ≥400, only age (ratio of expected counts (REC) 1.07 (95% CI 1.06 to 1.09)), hypertension (REC 1.24 (95% CI 1.09 to 1.41)), obesity (REC 1.34 (95% CI 1.20 to 1.50)), known CVD (REC 1.16 (95% CI 1.03 to 1.31)) and serum phosphate (REC 2.25 (95% CI 1.66 to 3.10) remained significantly associated, while smoking, diabetes, hyperlipidaemia, estimated glomerular filtration rate and serum calcium were not.

CONCLUSIONS

AVC was prevalent in the general population of men aged 60-74 years and was significantly associated with all modifiable cardiovascular risk factors, but only selectively after adjustment for CAC ≥400 AU.

TRIAL REGISTRATION NUMBER

NCT03946410 and ISRCTN12157806.

Population-Based Risk Factors for Ascending, Arch, Descending, and Abdominal Aortic Dilations for 60-74-Year-Old Individuals

BACKGROUND

Aortic dilations (ectasias and aneurysms) may occur on any segment of the aorta. Pathogenesis varies between locations, suggesting that etiology and risk factors may differ. Despite this discrepancy, guidelines recommend screening of the whole aorta if 1 segmental dilation is discovered.

OBJECTIVES

The purpose of this study was to determine the most dominant predictors for dilations at the ascending, arch, descending, and abdominal part of the aorta, and to establish comprehensive risk factor profiles for each aortic segment.

METHODS

Individuals aged 60-74 years were randomly selected to participate in DANCAVAS I+II (Danish Cardiovascular Multicenter Screening Trials). Participants underwent cardiovascular risk assessments, including blood samples, blood pressure readings, medical records, and noncontrast computed tomography scans. Adjusted odds ratios for potential risk factors of dilations were estimated by multivariate logistic analyses.

RESULTS

The study population consisted of 14,989 participants (14,235 men, 754 women) with an average age of 68 ± 4 years. The highest adjusted odd ratios for having any aortic dilation were observed when coexisting aortic dilations were present. Other noteworthy predictors included coexisting iliac dilations, hypertension, increasing body surface area, male sex, familial disposition, and atrial fibrillation, which were present in various combinations for the different aortic parts. Smoking and acute myocardial infarction were inversely associated with ascending and abdominal dilations. Diabetes was a shared protective factor.

CONCLUSIONS

Risk factors differ for aortic dilations between locations. The most dominant predictor for having a dilation at any aortic segment is the presence of an aortic dilation elsewhere. This supports current guidelines when recommending a full screening of the aorta if a focal aortic dilation is discovered.

Prevalence and extent of coronary artery calcification in the middle-aged and elderly population

AIMS

Coronary artery calcification (CAC) measured on cardiac computed tomography (CT) is an important risk marker for cardiovascular disease (CVD) and has been included in the prevention guidelines. The aim of this study was to describe CAC score reference values in the middle-aged and elderly population and to develop a freely available CAC calculator.

METHODS AND RESULTS

All participants from two population-based cardiac CT screening cohorts (DanRisk and DANCAVAS) were included. The CAC score was measured as a part of a screening session. Positive CAC scores were log-transformed and non-parametrically regressed on age for each gender, and percentile curves were transposed according to proportions of zero CAC scores. Men had higher CAC scores than women, and the prevalence and extend of CAC increased steadily with age. An online CAC calculator was developed, http://flscripts.dk/cacscore. After entering sex, age, and CAC score, the CAC score percentile and the coronary age are depicted including a figure with the specific CAC score and 25%, 50%, 75%, and 90% percentiles. The specific CAC score can be compared to the entire background population or only those without prior CVD.

CONCLUSION

This study provides modern population-based reference values of CAC scores in men and woman and a freely accessible online CAC calculator. Physicians and patients are very familiar with blood pressure and lipids, but unfamiliar with CAC scores. Using the calculator makes it easy to see if a CAC value is low, moderate, or high, when a physician in the future communicate and discusses a CAC score with a patient.

Prognostic importance of left atrial size measured by non-contrast cardiac computed tomography - A DANCAVAS study

BACKGROUND

Enlargement of left atrium (LA) is a valuable marker of cardiovascular events, and LA size is readily available while performing non-contrast cardiac computed tomography (NCCT) for preventive purposes. We aimed to evaluate the predictive value of a single LA area from NCCT in a population-based cohort.

METHOD

Mainly men aged 60-75 years from DANCAVAS were included. Traditional risk factors were recorded, and an NCCT scan performed at baseline. Coronary artery calcifications (CAC) score and the largest LA area were measured. LA was indexed to body surface area and categorised into four groups. Data on incident atrial fibrillation (AF), thromboembolic events, heart failure (HF) and death were obtained from Danish national registries.

RESULTS

In total, 14,557 individuals were eligible, excluding those without LA measurement (N = 232) and with heart valve replacement (N = 197). Known AF or HF were respectively excluded from follow-up. Median follow-up time was 2.1 to 3.4 years. In total, 304 developed AF, 149 had thromboembolism, 129 developed HF and 482 died. In adjusted analysis, LA enlargement was associated with AF (HR (95% CI): large 1.99 (1.46-2.71) and very large LA 3.77 (2.31-6.14)) and HF (large 2.40 (1.50-3.85) and very large LA 6.54 (4.07-10.51)). A very large LA significantly increased mortality (HR: 2.01 (1.44-2.82)), and was associated with a two-fold increased risk of thromboembolism; however, not significantly in adjusted analysis (p = 0.09).

CONCLUSION

We demonstrated that determination of LA area from NCCT was an important predictor of AF, HF and death. This knowledge could inform current risk assessment beyond CAC score.

Association of aortic valve calcification and vitamin K antagonist treatment

Aims 

Vitamin K antagonists (VKAs) are suspected of causing aortic valve calcification (AVC). The objective of this study was to clarify whether patients undergoing VKA treatment have increased AVC scores compared to patients treated with new oral anticoagulants (NOACs) and patients who never have been treated with VKA/NOAC.

Methods and results 

We included participants from the population-based DANCAVAS trial (n = 15 048). Information on confounders was collected, and the AVC scores were measured on non-contrast computed tomography scans. The participants’ medication data, including VKA and NOAC data, were collected from the Danish National Health Service Prescription Database. The final population consisted of 14 604 participants (67.4 years, 95% men) of whom 873 had been treated with VKA and 602 with NOAC. The association between AVC score and duration of anticoagulant use was investigated in an adjusted zero-inflated negative binomial regression model. For every year treated with VKA, the AVC score increased, on average, by 6% [ratio of expected counts (RECs) = 1.06; 95% confidence interval (CI) 1.02–1.10] compared to non-use. The results were consistent in sensitivity analyses excluding patients with known cardiovascular disease and statin users (REC = 1.07; 95% CI 1.02–1.11 and REC = 1.10; 95% CI 1.03–1.17, respectively). NOAC treatment was not significantly associated with AVC score in any of the corresponding models (REC = 1.03, 1.02, and 0.96).

Conclusion 

Compared to no treatment with anticoagulants, VKA use was associated with increased AVC score, while a similar association could not be established for NOAC.

Post-traumatic subdural hygromas: observations concerning a surgical enigma

Four per cent (38) of 881 head injured patients developed known subdural hygromas. Their times of onset and course were variable. However, only two large hygromas seemed clinically significant. Hygromas were more frequent when intracranial pressure monitors were placed, possibly due to opening of the arachnoid, particularly if intracranial pressure was low. But, of course, monitors were only inserted in more severely injured patients. The use of Richmond bolts to drain subdural hygromas in a controlled fashion while monitoring intracranial pressure is suggested.

Use of prognostic factors in improving the design and efficiency of clinical trials in childhood leukemia: Children's Cancer Study Group Report

Prognostic factors are exerting an increasingly apparent and important influence on the results of comparative treatment regimens in childhood leukemia. Since February 1975, 883 previously untreated children with acute lymphocytic leukemia were entered in a protocol designed to evaluate prognostic factors that influence induction rate, remission duration, and survival and to identify subsets of patients with a high risk of early failure. Stratification was based upon the initial wbc count, and standard and more intensive induction and maintenance therapy programs were compared. The combination of older age (> 10 years), high initial wbc counts (greater than or equal to 20 x 10(9)/liter), and low serum IgG is associated with a significantly lower rate of induction of complete remission. The following factors were associated with an unfavorable prognosis with regard to bone marrow relapse and death: wbc count of greater than or equal to 20 x 10(9)/liter; age > 7 years old; CNS disease at diagnosis; L2 lymphoblasts; hemoglobin level greater than or equal to 11 g/dl; decreased concentration of serum immunoglobulin; and M3 marrow on Day 14 of induction. None of the 41 patients in the low-risk prognostic group (3-7 years old with an initial wbc count of < 10 x 10(9)/liter) with L1 blast cells, normal Ig, and M1 marrow on Day 14 has sustained an adverse event. Identification of prognostic factors should permit more efficient and effective design of future protocols by refining the classification of acute lymphocytic leukemia, decreasing the toxic risk to patients with a better prognosis, and improving the relatively poor remission duration and survival for patients with a poor prognosis.

L-Asparaginase, vincristine, and prednisone for induction of first remission in acute lymphocytic leukemia

L-Asparaginase was added to vincristine and prednisone for induction of first remission in 815 children with acute lymphocytic or acute undifferentiated leukemia. This combination resulted in an overall remission rate of 93%. The addition of L-asparaginse to the standard induction regimen using prednisone and vincristine did not significantly increase the morbidity or mortality rate during the induction period. The most common side effect was transient L-asparaginase-induced hyperglycemia. The safe administration of L-asparaginase i.m. and the dose efficacy of 6000 I.U./sq m were confirmed. For these reasons, L-asparaginase should be combined with vincristine and prednisone for the initial induction of children with acute lymphocytic or acute undifferentiated leukemia.

Effect of adriamycin on DNA, RNA, and protein synthesis in cell-free systems and intact cells

The effect of adriamycin on DNA, RNA, and protein synthesis was investigated in cell-free systems and intact cells. In studies with purified mammalian cell enzymes, adriamycin produced a greater inhibition of DNA-dependent DNA polymerase than of RNA polymerase. The extent of inhibition of both these enzymes was decreased by increasing the concentration of the DNA template in the reaction mixture. In studies with isolated nuclei, adriamycin was also a more potent inhibitor of DNA synthesis than RNA synthesis. However, with intact cells, adriamycin inhibited both DNA and RNA synthesis to about the same extent. The inhibition produced by adriamycin on RNA synthesis in intact cells was greater than that observed in the cell-free systems. Adriamycin inhibited protein synthesis in a cell-free system consisting of polyribosomes, transfer RNA, and enzymes but did not inhibit protein synthesis in intact cells. These differences in the pattern of inhibition may be due to biotransformation of the drug and/or preferential binding to chromosomal DNA in the intact cell.

Detection of bacterial endotoxin in antitumor agents

The Limulus amebocyte lysate assay was used to detect the presence of bacterial endotoxin in a variety of chemotherapeutic agents currently in use. Results were quantitated using a standard Escherichia coli endotoxin curve. Relative concentrations of endotoxin ranging from 0.1 to 63 ng/ml were detected in individual lots of L-asparaginase, 5-azacytidine, bleomycin, DTIC, actinomycin D, adriamycin, and vinblastine diluted to normal concentrations for injection. When multiple lots of a given drug were tested, at least one lot produced a negative assay, indicating less than 0.1 ng/ml of endotoxin in 50% of these drugs. All lots of cytosine arabinoside, cyclophosphamide, daunorubicin, vincristine, and streptozotocin tested had less than 0.1 ng/ml of endotoxin. Inactivation kinetics of the Limulus-positive drug material in dilute alkali solutions were identical to those of E. coli endotoxin. The Limulus lysate test is a rapid and specific method for the detection of small amounts of bacterial endotoxin contaminating parenteral preparations of antitumor agents.

Intensive chemotherapy as primary treatment for rhabdomyosarcoma of the pelvis

Twenty-six cases of childhood rhabdomyosarcoma involving the pelvis were treated at Childrens Hospital of Los Angeles between 1950 and 1972. The median survival of 17 patients treated up to 1970 was 6 months. Of a group of 9 patients treated with intensive chemotherapy (ICG) prior to surgery and/or x-ray therapy, 5 are surviving from 12 to 60 months and have a relative survival rate of 4.5 times that of the mixed therapy group (MTG) (p = 0.01). Deaths have occurred only in patients with Stage IV disease. The use of preoperative chemotherapy with or without x-ray therapy followed by local surgical excision when necessary can be as effective in prolonging the survival of children with pelvic rhabdomyosarcoma as those obtained with more traditional approaches; this limitation in use of surgery is likely to preserve the quality of life, should the child live to adulthood.

In vitro biochemical and cytotoxicity studies with 1-beta-D-arabinofuranosylcytosine and 5-azacytidine in combination

The effect of 1-beta-D-arabinofuranosylcytosine (ara-C) and 5-azacytidine (5-aza-C), alone and in combination, on DNA synthesis and cytotoxicity in hamster fibrosarcoma cells has been studied. After a 2-hr exposure of S-phase cells to ara-C at concentrations of 2 to 200 muM, the cells required about 4 to 6 hr to recover from inhibition of DNA synthesis. When 2 exposures to ara-C were used, maximal cytotoxicity occurred when the 2nd dose of ara-C was administered at the time when the cells recovered from the inhibition of DNA synthesis. When the S-phase cells were exposed to ara-C, the maximal killing effect of 5-aza-C occurred when this agent was administered 6 hr later, at the time when the cells had recovered from the inhibition of DNA synthesis. When S-phase cells were exposed to 5-aza-C, the maximal cell kill produced by ara-C also occurred 5 to 6 hr later. When the S-phase cells were exposed simultaneously to both ara-C and 5-aza-C, significant antagonism with respect to cytotoxicity was observed between these 2 agents. When cells in G1 were exposed to 5-aza-C, the cytotoxicity produced by ara-C on these cells when they entered S phase was additive with respect to the cytotoxicity produced by 5-aza-C exposure alone.

BCG in the treatment of acute lymphocytic leukemia

Children with acute lymphocytic leukemia, who were in remission after induction with prednisone and vincristine and consolidation with intravenous methotrexate, were randomized into three groups receiving (1) no further therapy, (2) BCG, and (3) chemotherapy with biweekly methotrexate and monthly prednisone and vincristine. Children continuing in remission after 8 mo on chemotherapy in group 3 were rerandomized into three similar groups, i.e., no therapy, BCG, and chemotherapy. In the primary randomization, the median duration of remission was identical in the groups receiving no therapy or BCG, (4 and 4.3 mo respectively), and both were significantly less than the median duration of remission on chemotherapy which had not been reached prior to secondary randomization at 8 mo. Results of secondary randomization were similar to those of primary randomization. As used in this study, BCG was ineffective in prolonging drug-induced remissions either early in remission or when the leukemic cell population might have been further reduced after 8 mo of maintenance chemotherapy.

Cellular phosphorylation of 1-beta-D-arabinofuranosylcytosine 5-azacytidine with intact fibrosarcoma and leukemic cells

The phosphorylation of 1-beta-D-arabinofuranosylcytosine (ara-C) and 5-azacytidine (5-aza-C) by A(T1)C1-3 hamster fibrosarcoma cells and L5178Y murine leukemic cells was studied, using intact cells. The cellular phosphorylation of both these nucleoside analogs appears to follow Michaelis-Menton kinetics. The apparent Km value for ara-C in the fibrosarcoma and leukemic cells was about 40 muM, whereas the apparent Km values for 5-aza-C in these cells were about 1.3 and 0.41 mM, respectively. Deoxycytidine and cytidine were found to be potent competitive inhibitors of the phosphorylation of ara-C and 5-aza-C, respectively, ara-C and 5-aza-C were found to be weak competitive inhibitors of the phosphorylation of deoxycytidine and cytidine, respectively. A clone isolated from the fibrosarcoma cells that was partially resistant to the cytotoxic effects of ara-C exhibited a higher Km value for both ara-C and deoxycytidine than the wild-type fibrosarcoma cells.

Dibromodulcitol (NSC-104800) compared with cyclophosphamide (NSC-26271) as remission maintenance therapy in previously treated children with acute lymphoblastic leukemia or acute undifferentiated leukemia: possible effectiveness in reducing the incidence of central nervous system leukemia

Dibromodulcitol and cyclophosphamide are both alkylating agents. In this study, these two drugs were compared for their effectiveness as remission maintenance therapy for childhood acute lymphoblastic leukemia or acute undifferentiated leukemia. Toxic effects were similar in both groups of patients although cystitis did not occur with the dibromodulcitol treatment. The duration of remission was slightly shorter for dibromodulcitol than for cyclophosphamide (P = 0.04). There was, however, a lower incidence of CNS leukemia in the patients treated with dibromodulcitol, which did not seem to be related to a basic difference in the patient groups.

Inhibitory effects of mitogens on adenoidal lymphocytes in vitro

Cultures of human adenoidal lymphocytes exposed briefly to either phytohemagglutinin (PHA), Staphylococcus filtrate (Staph-F), concanavalin-A (Con-A), or pokeweed mitogen (PWM) incorporate increased amounts of thymidine earlier than replicate cultures exposed continuously to the mitogens. These effects can begin in the first 24 hr of culture and are seen maximally between 36 and 72 hr. Once a blastogenic response is established, PHA or PWM can diminish that response. Inhibition with PWM requires that the initial stimulation was with this mitogen, while PHA can inhibit blastogenesis to both PHA and PWM-stimulated cells. Because these mitogens can have a paradoxical effect on adenoidal lymphocytes, being capable of both initiating and inhibiting DNA synthesis, this phenomena should be kept in mind when such systems are utilized for the evaluation of antigens and drug effects.

The treatment of acute childhood leukemia: predictions for the future based on extrapolations from the past

Further progress in the treatment of acute leukemia involves a careful assessment of host and disease factors in each child and the selection of a therapeutic regimen which interacts with these factors to provide the maximum chance for survival. For some children, this therapy can be carried out in the community by expertly trained hematologist-oncologists; for others, the best treatment will involve clinical research at a center. Such a general approach has the best chance of fulfilling the optimistic survival projections made by the President's Cancer Panel in 1973 for acute lymphocytic leukemia.

1-beta-D-arabinofuranosylcytosine-induced chromatid breakage: effect of inhibition of DNA synthesis

The frequency of chromatid breakage induced by 1-beta-D-arabinofuranosylcytosine was decreased when hamster cell fibroblasts were treated with chemical agents that interferred with DNA synthesis immediately before addition of the analog. This phenomenon occurred in both the S and G2 phases of the cell cycle.

Chromatid breakage: differential effect of inhibitors of DNA synthesis during G 2 phase

The cell cycle specificity of chromatid breakage induced by inhibitors of DNA synthesis depends on the mechanism of drug action. 5-Hydroxy-2-formylpyridine thiosemicarbazone, hydroxyurea, and guanazole, compounds that inhibit ribonucleotide reductase, do not cause chromatid breakage during G(2) phase. In contrast, two active antitumor agents, arabinosylcytosine and 5-azacytidine, which are either incorporated into polynucleotides or affect DNA polymerase, produce chromatid breakage during G(2) phase. All of these agents except guanazole also induce breakage in S phase.

Effective combination treatment of advanced acute lymphocytic leukemia with cytosine arabinoside (NSC-63878) and L-asparaginase (NSC-109229)

The combination of cytosine arabinoside and L-asparaginase induced remission in 15 of 22 children (68%) with previously treated acute lymphocytic leukemia (ALL). Eight of these patients were in remission after the second week of treatment and seven were in remission after the fourth week. The combination was well tolerated. These preliminary results suggest that these two agents have an additive therapeutic effect in inducing remissions in children with advanced ALL.

Chromatid breakage: cytosine arabinoside-induced lesions inhibited by ultraviolet irradiation

Exposure to ultraviolet light can reduce the frequency of chromatid breaks induced by cytosine arabinoside in the DNA synthetic and post-DNA synthetic phases of the cell cycle. This effect can be correlated temporally with a decrease in the uptake of tritiated thymidine after ultraviolet treatment, implying that the genesis of such breakage is intimately related to DNA synthesis and that such synthesis is not confined to the DNA synthetic phase.

Effect of 1-beta-D-arabinofuranosylcytosine on cell cycle passage time

1-beta-D-Arabinofuranosylcytosine (ara-C) affects the passage rate of cells from S to G2 phase to a greater extent than from G1 to S. This finding is consistent with the fact that the compound may have its major biological effect during the latter part of S and the early part of G2. The magnitude of these effects is related to the dose and duration of ara-C administration. Inhibition of DNA synthesis can occur without disturbances in transit time.

An approach to the emotional support of fatally ill children

When children with leukemia were en couraged to ask questions about their ill ness, they asked many. These questions were straightforward, demonstrating their interest in learning about their illness, and emphasiz ing their need to place events in perspective. Much of the staff's initial fear and appre hension regarding their ability to deal with problems centering around life and death were gradually resolved as they began to ap proach these problems with the information gathered from the children rather than with the preconceived prejudices obtained from other adults.