Socioeconomic inequalities in depression: a meta-analysis

Low socioeconomic status (SES) is generally associated with high psychiatric morbidity, more disability, and poorer access to health care. Among psychiatric disorders, depression exhibits a more controversial association with SES. The authors carried out a meta-analysis to evaluate the magnitude, shape, and modifiers of such an association. The search found 51 prevalence studies, five incidence studies, and four persistence studies meeting the criteria. A random effects model was applied to the odds ratio of the lowest SES group compared with the highest, and meta-regression was used to assess the dose-response relation and the influence of covariates. Results indicated that low-SES individuals had higher odds of being depressed (odds ratio = 1.81, p < 0.001), but the odds of a new episode (odds ratio = 1.24, p = 0.004) were lower than the odds of persisting depression (odds ratio = 2.06, p < 0.001). A dose-response relation was observed for education and income. Socioeconomic inequality in depression is heterogeneous and varies according to the way psychiatric disorder is measured, to the definition and measurement of SES, and to contextual features such as region and time. Nonetheless, the authors found compelling evidence for socioeconomic inequality in depression. Strategies for tackling inequality in depression are needed, especially in relation to the course of the disorder.

Variable Very-High-Energy Gamma-Ray Emission from the Microquasar LS I +61 303

Microquasars are binary star systems with relativistic radio-emitting jets. They are potential sources of cosmic rays and can be used to elucidate the physics of relativistic jets. We report the detection of variable gamma-ray emission above 100 gigaelectron volts from the microquasar LS I 61 + 303. Six orbital cycles were recorded. Several detections occur at a similar orbital phase, which suggests that the emission is periodic. The strongest gamma-ray emission is not observed when the two stars are closest to one another, implying a strong orbital modulation of the emission or absorption processes.

Resistance of germfree rats to indomethacin-induced intestinal lesions

Indomethacin given orally to conventional rats produced in three days a syndrome, often fatal, of intestinal lesions characterized by multiple ulcers and peritonitis. Male germfree rats were found to be resistant to this effect of indomethacin, while female germfree rats developed very mild lesions. Germfree rats became sensitive again to such lesions when monocontaminated with E. coli. In such animals, however, the lesions were less severe than in conventional animals, presumably because more than one microorganism is necessary for the full syndrome to develop. These results suggest that microorganisms are necessary for the development of indomethacin-induced intestinal lesions. Secondary bile acids, absent in germfree animals, may also be necessary. The prostaglandin deficiency caused by indomethacin appears to weaken the resistance of the intestinal mucosa to microorganisms and/or their toxins. The latter may then penetrate the mucosa, damage the cells and produce ulcers and perforations. Since several prostaglandins also protect against indomethacin-induced lesions, the hypothesis is advanced that certain prostaglandins may protect the mucosa ("cytoprotection") by preventing the spread of microorganisms and/or their toxin through the intestinal wall.

A Bose-Einstein condensate of metastable atoms

We report the realization of a Bose-Einstein condensate of metastable atoms (helium in the lowest triplet state). The excitation energy of each atom with respect to the ground state is 20 electron volts, but inelastic processes that would destroy the sample are suppressed strongly enough in a spin-polarized sample to allow condensation. Our detection scheme takes advantage of the metastability to achieve detection of individual atoms as well as of the decay products of inelastic processes. This detection opens the way toward new studies in mesoscopic quantum statistical physics, as well as in atomic quantum optics.

Enteropooling assay: a test for diarrhea produced by prostaglandins

An assay (enteropooling assay) to test the diarrheogenic property of prostaglandins is described. Fasted rats are given a prostaglandins either orally or subcutaneously, and are killed 30 min later. The entire small intestine is removed and its contents collected into a test tube. The greater the volume of this intestinal fluid, the more diarrheogenic is the prostaglandin. The assay is simple, rapid, quantitative, and predictive of diarrhea. It can be used to grade the relative diarrhoegenic activity of prostaglandins as well as to test agents that may block this effect. The accumulation of fluid into the small intestine is called "enteropooling". It is the sum of (a) the fluid being excreted from the blood into the lumen, and (b) to a lesser extent, the portion of fluid already into the lumen but whose absorption is inhibited by the prostaglandin. The degree of enteropooling depends also on how much fluid flows from the small to the large intestine. Our results support the hypothesis that the diarrhea observed after administration of high doses of prostaglandins is due to accumulation of abundant fluid into the small intestine, and not intestinal hypermotility. This fluid is then carried into the large intestine and eventually expelled as diarrhea. Agents other than prostaglandins were tested for enteropooling activity. Laxatives such as castor oil, hypertonic solutions and bile salts caused enteropooling.

Long-term results of three randomized trials (58831, 58832, 58881) in childhood acute lymphoblastic leukemia: a CLCG-EORTC report. Children Leukemia Cooperative Group

We present here the long-term results of three randomized clinical trials conducted on children with newly diagnosed acute lymphoblastic leukemia (ALL) between 1983 and 1998 by the Children Leukemia Cooperative Group (CLCG) from EORTC. In study 58831/32, the overall event-free survival (EFS) rates (+/- s.e.) at 6 and 10 years were 66% +/- 1.8% and 65% +/- 1.8%, respectively, and the risk of isolated central nervous system (CNS) relapse was 6% +/- 1% and 7% +/- 1%, respectively. In patients with a standard risk of relapse the omission of cyclophosphamide had no adverse effect on disease-free survival rates at 10 years (trial 58831). In medium- and high-risk patients the omission of radiotherapy did not increase the risk of CNS or systemic relapse (trial 58832). In study 58881 (1989-1998) the overall EFS rate at 8 years was 68.4% +/- 1.2% and the risk of isolated CNS relapse was 4.2%+/-0.5%. In this trial which adressed three randomized questions, the following results were obtained: the combination of cytarabine at high doses with methotrexate at high doses during interval therapy did not improve prognosis. The addition of 6-mercaptopurine iv during maintenance increased the risk of late relapse. E. coli asparaginase was more toxic and has a higher efficacy than Erwinia asparaginase. Leukocyte counts >100 x 10(9)/l, specific genetic abnormalities, a poor initial response to steroids or a high level of minimal residual disease at early time points were consistently associated with an adverse prognosis in the 58881 trial.

Improved survival rate in children with stage III and IV B cell non-Hodgkin's lymphoma and leukemia using multi-agent chemotherapy: results of a study of 114 children from the French Pediatric Oncology Society

Children with B cell non-Hodgkin's lymphoma who have not relapsed 1 year after diagnosis and treatment are generally cured. We report here the results of treatment in 114 children who all had a minimum follow-up of 20 months. The protocol LMB 0281 from the French Pediatric Oncology Society was used. This nine-drug intensive-pulsed chemotherapy was based on high-dose cyclophosphamide, high-dose methotrexate (HD MTX), and cytosine arabinoside (ara-C) in continuous infusion. CNS prophylaxis was with chemotherapy only. No local irradiation was performed. No debulking surgery was recommended. There were 72 patients with stage III lymphoma and 42 patients with stage IV lymphoma or B cell acute lymphocytic leukemia (B-ALL). Among those 42 patients, seven had CNS involvement alone, 21 had bone marrow alone, and 14 had both; 26 had greater than 25% blast cells in bone marrow, 14 of whom had blast cells in blood. The primary site of involvement was the abdomen in 90 patients, the Waldeyer Ring in nine, and various sites in eight; seven patients presented without tumor. Seventy-seven patients are alive with a median follow-up of 2 years and 8 months. Seven patients died due to initial treatment failure, 11 died from toxicity, and 19 died after relapse. Among the 93 patients without initial CNS involvement, only one isolated relapse in CNS occurred. Survival and disease-free survival rates reached 67% and 64%, respectively, for all patients, 75% and 73% for stage III patients and 54% and 48% for stage IV and B-ALL patients. Bone marrow involvement was not an adverse prognostic factor. Contrary initial CNS involvement indicated a bad prognosis with a disease-free survival rate of 19% compared with 76% without CNS disease. This study showed that CNS prophylaxis and local control of the primary tumor can be achieved by intensive chemotherapy alone, without radiotherapy or debulking surgery.

Insect immunity. Constitutive expression of a cysteine-rich antifungal and a linear antibacterial peptide in a termite insect

Two novel antimicrobial peptides, which we propose to name termicin and spinigerin, have been isolated from the fungus-growing termite Pseudacanthotermes spiniger (heterometabole insect, Isoptera). Termicin is a 36-amino acid residue antifungal peptide, with six cysteines arranged in a disulfide array similar to that of insect defensins. In contrast to most insect defensins, termicin is C-terminally amidated. Spinigerin consists of 25 amino acids and is devoid of cysteines. It is active against bacteria and fungi. Termicin and spinigerin show no obvious sequence similarities with other peptides. Termicin is constitutively present in hemocyte granules and in salivary glands. The presence of termicin and spinigerin in unchallenged termites contrasts with observations in evolutionary recent insects or insects undergoing complete metamorphosis, in which antimicrobial peptides are induced in the fat body and released into the hemolymph after septic injury.

Functional N-methyl-D-aspartate receptors in O-2A glial precursor cells: a critical role in regulating polysialic acid-neural cell adhesion molecule expression and cell migration

The capacity for long-distance migration of the oligodendrocyte precursor cell, oligodendrocyte-type 2 astrocyte (O-2A), is essential for myelin formation. To study the molecular mechanisms that control this process, we used an in vitro migration assay that uses neurohypophysial explants. We provide evidence that O-2A cells in these preparations express functional N-methyl-D-aspartate (NMDA) receptors, most likely as homomeric complexes of the NR1 subunit. We show that NMDA evokes an increase in cytosolic Ca2+ that can be blocked by the NMDA receptor antagonist AP-5 and by Mg2+. Blocking the activity of these receptors dramatically diminished O-2A cell migration from explants. We also show that NMDA receptor activity is necessary for the expression by O-2A cells of the highly sialylated polysialic acid-neural cell adhesion molecule (PSA-NCAM) that is required for their migration. Thus, glutamate or glutamate receptor ligands may regulate O-2A cell migration by modulating expression of PSA-NCAM. These studies demonstrate how interactions between ionotropic receptors, intracellular signaling, and cell adhesion molecule expression influence cell surface properties, which in turn are critical determinants of cell migration.

Interleukin-1 is cytoprotective, antisecretory, stimulates PGE2 synthesis by the stomach, and retards gastric emptying

Human recombinant interleukin 1 beta (IL-1) administered intraperitoneally to rats produced the following gastric effects: 1. It was cytoprotective, preventing gastric mucosal necrosis produced by oral administration of one ml of absolute ethanol to fasted animals. The ED50 was 1200 units/kg (110 ng per animal). IL-1 was 125 times more potent than prostaglandin E2 (on a weight basis), and 6,000 times more potent (on a molar basis). 2. The cytoprotective effect of IL-1 was blocked by indomethacin (inhibitor of prostaglandin synthesis) and by IRAP (a specific interleukin-1 receptor antagonist protein). IRAP did not inhibit cytoprotection induced by PGE2. 3. IL-1 prevented the formation of gastric erosions induced by aspirin. 4. IL-1 inhibited gastric secretion (volume, acid concentration and output), in the pylorus-ligated rat, with an ED50 of 300 units/kg (3.2 ng per animal). 5. Indomethacin and IRAP blocked the antisecretory effect of IL-1. 6. IL-1 retarded gastric emptying, an effect blocked by IRAP, but not by indomethacin. 7. IL-1 increased synthesis of prostaglandin E2 by the gastric mucosa by 111%. IL-1 is the most potent of known agents that are gastric cytoprotective, antiulcer, antisecretory, and delay gastric emptying. It appears to act mostly by stimulating the synthesis of prostaglandins by the stomach. These studies suggest that the stomach possesses IL-1 receptors. These are probably located on parietal cells (that produce acid), on prostaglandin-producing cells, on smooth muscle cells (responsible for gastric emptying), and on as yet unidentified cells involved in gastric cytoprotection. Both IL-1 and IRAP, being natural substances, may play a physiological role in the maintenance of gastric mucosal integrity, and in the regulation of acid secretion and gastric motility.

Localized childhood Hodgkin's disease: response-adapted chemotherapy with etoposide, bleomycin, vinblastine, and prednisone before low-dose radiation therapy-results of the French Society of Pediatric Oncology Study MDH90

PURPOSE

The French Society of Pediatric Oncology MDH82 study demonstrated the effectiveness of 20 Gy irradiation of involved fields after doxorubicin, bleomycin, vinblastine, and dacarbazine (ABVD) or mechlorethamine, vincristine, procarbazine, and prednisone/ABVD chemotherapy in children with localized Hodgkin's disease (HD). The response to primary chemotherapy was the only predictor of survival. To reduce long-term treatment complications without compromising efficacy, the MDH90 study was based on a new chemotherapy regimen devoid of both alkylating agents and anthracycline, followed by 20 Gy of radiotherapy (RT) for good responders.

PATIENTS AND METHODS

From January 1990 to July 1996, 202 children were enrolled from 30 institutions. Good responders to four cycles of vinblastine, bleomycin, etoposide (VP16), and prednisone (VBVP) were given 20 Gy of RT and no further therapy. Poor responders were given vincristine, procarbazine, prednisone, and doxorubicin. After a second evaluation, good responders were given 20 Gy of RT, and poor responders were given 40 Gy of RT.

RESULTS

One hundred seventy-one patients (85%) were good responders to VBVP, 27 (15%) were poor responders, and four did not respond. With a median follow-up of 74 months (range, 25 to 117 months), the 5-year overall survival rate (mean +/- SD) is 97.5% +/- 2.1%, and the event-free survival rate (mean +/- SD) is 91.1% +/- 1.8%. Significant predictors of worse event-free survival in multivariate analysis were hemoglobin < 10.5 g/L, "b" biologic class, and nodular sclerosis.

CONCLUSION

These results suggest that most children with clinical stage I and II HD can be treated with chemotherapy devoid of alkylating agents and anthracycline, followed by low-dose RT.

Chronic aristolochic acid toxicity in rabbits: a model of Chinese herbs nephropathy?

BACKGROUND

Chinese herbs nephropathy (CHN) is a new type of subacute interstitial nephritis that is attributed to aristolochic acid (AA), which inadvertently has been included in slimming pills. The contribution of other simultaneously prescribed drugs remains disputed. In the present study, the effects of a chronic intake of AA given as a single drug was evaluated through renal histology and function in rabbits.

METHODS

Female New Zealand White rabbits were injected intraperitoneally with either 0.1 mg AA/kg or with saline 5 days a week for 17 to 21 months. Body weight, renal function, and urinary excretion of glucose and low molecular weight proteins were monitored prior to sacrifice at the end of the study period.

RESULTS

All animals given AA developed renal hypocellular interstitial fibrosis, which was classified into three patterns. Fibrosis was confined to medullary rays (MRs) in pattern I (N = 3), extended to the outer cortical labyrinth (OCL) in pattern II (N = 2), and eventually to the inner cortical labyrinth (ICL) in pattern III (N = 6). Fibrosis in MR and OCL was associated with mainly proximal tubular epithelial cell flattening. All treated animals displayed urothelial atypia. Three of them also developed tumors of the urinary tract. No significant pathologic changes were found in control rabbits. AA-treated animals differed from controls by an impaired growth, increased serum creatinine, glucosuria, tubular proteinuria, and anemia.

CONCLUSION

The observed pattern of renal histopathological lesions and disorders of the renal function, as well as urothelial atypia and malignancy, are very reminiscent of CHN. Our observations therefore support a causal role of AA alone in the genesis of this new nephropathy.

Identification of new prognosis factors from the clinical and epidemiologic analysis of a registry of 229 Diamond-Blackfan anemia patients. DBA group of Société d'Hématologie et d'Immunologie Pédiatrique (SHIP), Gesellshaft für Pädiatrische Onkologie und Hämatologie (GPOH), and the European Society for Pediatric Hematology and Immunology (ESPHI)

Diamond-Blackfan anemia (DBA) is a constitutional disease characterized by a specific maturation defect in cells of erythroid lineage. We have assembled a registry of 229 DBA patients, which includes 151 patients from France, 70 from Germany, and eight from other countries. Presence of malformations was significantly and independently associated with familial history of DBA, short stature at presentation (before any steroid therapy), and absence of hypotrophy at birth. Two hundred twenty-two patients were available for long-term follow-up analysis (median, 111.5 mo). Of these individuals, 62.6% initially responded to steroid therapy. Initial steroid responsiveness was found significantly and independently associated with older age at presentation, familial history of DBA, and a normal platelet count at the time of diagnosis. Severe evolution of the disease (transfusion dependence or death) was significantly and independently associated with a younger age at presentation and with a history of premature birth. In contrast, patients with a familial history of the disease experienced a better outcome. Outcome analysis revealed the benefit of reassessing steroid responsiveness during the course of the disease for initially nonresponsive patients. Bone marrow transplantation was successful in 11/13 cases; HLA typing of probands and siblings should be performed early if patients are transfusion dependent, and cord blood should be preserved. Incidence of DBA (assessed for France over a 13-y period) is 7.3 cases per million live births without effect of seasonality on incidence of the disease or on malformative status. Similarly, no parental imprinting effect or anticipation phenomenon could be documented in families with dominant inheritance.

Involvement of lipogenesis in the lower VLDL secretion induced by oligofructose in rats

Dietary supplementation with oligofructose (OFS; 100 g/kg), a non-digestible oligomer of beta-D-fructose, decreases serum triacylglycerols in serum and VLDL of rats. In order to investigate the role of hepatic metabolism in the hypolipidaemic effect of OFS, male Wistar rats were fed on a standard diet with or without 100 g Raftilose P95/kg as OFS source for 30 d. OFS feeding (1) significantly decreased triacylglycerol and phospholipid concentrations in both blood and liver, (2) increased the glycerol-3-phosphate liver content but decreased the hepatic activity of glycerol-3-phosphate acyltransferase (EC 2.3.1.15), suggesting a decrease in acylglycerol synthesis, (3) did not affect the blood non-esterified fatty acid concentrations, but (4) reduced by 54% the capacity of isolated hepatocytes to synthesize and secrete triacylglycerols from labelled acetate; the activity of fatty acid synthase, a key lipogenic enzyme was also significantly decreased. These findings suggest that OFS decreases serum triacylglycerols by reducing de novo fatty acid synthesis in the liver; the lower insulin level in the serum of OFS-fed rats could explain, at least partly, the metabolic effect induced by such non-digestible carbohydrates.

Induction of protective immunity in rodents by vaccination with a prokaryotically expressed recombinant fusion protein containing a respiratory syncytial virus G protein fragment

A subunit approach to the development of a respiratory syncytial virus (RSV) vaccine was investigated. It involved the production, in Escherichia coli, of an RSV (Long) G protein fragment (G2Na) as a C-terminal fusion partner to an albumin binding region (BB) of streptococcal protein G. G2Na incorporated amino acid residues 130-230 and was specifically recognized by murine anti-RSV-A polyclonal serum. In mice, intraperitoneal immunization with BBG2Na induced high anti-RSV-A serum ELISA titers and low to moderate neutralization activity. The immune response induced by BBG2Na demonstrated a potent protective efficacy against upper and lower respiratory tract RSV-A infection. The immunogenicity and protective efficacy of BBG2Na was maintained for at least 47 and 48 weeks, respectively, and was as potent and durable as live RSV-A administered in a similar fashion. Intramuscular immunization of cotton rats with BBG2Na protected lungs from both homologous and heterologous virus challenge. In contrast to mice, however, cotton rat nasal tracts were not protected after BBG2Na immunization. Consistent with antibody-mediated protection, virus was cleared within 24 hr from the lungs of BBG2Na-immunized mice. The anti-RSV-A antibodies induced in mice were exclusively of the IgG1 isotype and were detected in the serum, lungs, and nasal tracts. Passive transfer of these antibodies prevented acute, and eliminated chronic, RSV-A lung infection in normal and immunodeficient mice, respectively, confirming that such antibodies are important and sufficient for BBG2Na-induced pulmonary protection. Our results clearly demonstrate that BBG2Na contains an important immunogenic domain of the RSV G protein. The prokaryotic origin of this protein indicates that glycosylation of the RSV G protein is not necessary for protective efficacy. Thus, BBG2Na has potential as an RSV subunit vaccine.

Outcome of Childhood Acute Promyelocytic Leukemia With All-Trans-Retinoic Acid and Chemotherapy

Purpose

To determine the results of treatment combining all-trans-retinoic acid (ATRA) and chemotherapy (CT) in childhood acute promyelocytic leukemia (APL).

Patients and Methods

Children (< 18 years) with newly diagnosed APL were included in the APL93 trial, treated by ATRA followed or combined with daunorubicin-cytarabine, and then randomly assigned between no maintenance, intermittent ATRA, continuous CT, or both.

Results

Of the 576 patients included in APL93 trial, 31 (5%) were children, including 22 girls (71%) and nine boys (29%). Thirty of the children (97%) obtained complete remission (CR). ATRA syndrome occurred in four children (13%), who all achieved CR, and headaches occurred in 12 children (39%), with signs of pseudotumor cerebri in five children (16%). Seven patients (23%) relapsed. None of the eight patients who received both ATRA and CT for maintenance relapsed. All relapsing patients achieved a second CR. Twenty-two patients remained in first CR after 43+ to 96+ months, six remained in second CR after 17+ to 66+ months, and three patients had died. The 5-year event-free survival (EFS), relapse, and overall survival rates were 71%, 27%, and 90%, respectively. No difference between adults and children included in the APL93 trial was seen for CR rate, 5-year relapse rate, EFS, and overall survival, but significantly better survival was seen in children after adjustment on WBC counts (P = .02) and incidence of microgranular M3 variant (P = .04).

Conclusion

ATRA combined with CT for induction and also probably for maintenance provides as favorable results in children with APL as in adults and currently constitutes the reference first-line treatment in both age groups.

Prevention by mild irritants of gastric necrosis produced in rats by sodium taurocholate

Acidified sodium taurocholate, 80 mmol given orally to rats, produced extensive gastric lesions within 1 hr. A variety of milk irritants (0.15--0.35 N HCl; 10--25% ethanol; 5 mmol of acidified taurocholate) given orally 15 min before 80 mmol of taurocholate protected the stomach in a dose-dependent manner. This phenomenon is called "adaptive cytoprotection." The mild irritants are believed to elicit the endogenous formation of prostaglandin (PG) by the gastric mucosa; these PGs would prevent gastric injury through their cytoprotective property. Results with indomethacin, an inhibitor of the enzyme (PG cyclooxygenase) that transforms arachidonic acid into PG, supports this conclusion. Indomethacin given subcutaneously or orally 75 min before the mild irritants blocked their protective effect, presumably by preventing the formation of PG by the stomach. Endogenous PG may be formed continually by the stomach in response to the various "irritants" normally present in the lumen, such as foodstuffs at a wide range of pH and temperatures, exogenous agents such as alcohol and drugs, as well as bile refluxing from the duodenum. This biosynthesis of PG may be a physiological phenomenon that explains why the stomach remains intact in spite of being bathed with noxious agents.

High-dose chemoradiotherapy with bone marrow transplantation as consolidation treatment in neuroblastoma: an unselected group of stage IV patients over 1 year of age

Since January 1983, 56 consecutive children over 1 year of age with stage IV neuroblastoma entered an aggressive protocol, including chemotherapy, radiation therapy, and bone marrow transplantation. The induction protocol included platinum and epipodophyllotoxin (VM-26), alternating with cyclophosphamide, Adriamycin (Adria Laboratories, Columbus, OH), and vincristine (PE/CADO). Surgery was performed after 2 to 4 months, and consolidation with intensive chemoradiotherapy and bone marrow transplantation (BMT) was performed within 12 months of diagnosis. The combination of vincristine, melphalan and total body irradiation (TBI) was used before BMT, and no further treatment was administered before progression. With the exception of two allografts, autologous BMT (ABMT) was given in all cases and was purged using an immunomagnetic procedure (Kemshead technique) in 32 of 35 cases, and a chemical procedure in three of 35. Of the 56 patients, 45 were evaluable. Of those, 23 were grafted in partial remission (PR), and 14 were grafted in either complete remission (CR) or very good partial remission (VGPR). The acute toxic death rate was 19%, the relapse rate was 32%, and the progressive disease rate was 19%. The progression-free survival in the CR/VGPR group (ie, 44% at 32 months post-diagnosis) and in the PR group (13% at 32 months) was not significantly different (P greater than .05). At 24 months, the overall survival of the 56 unselected patients was 39% compared with 12% for comparable patients previously treated by our group (P less than .005).

Infectious diseases in the first year of life, perinatal characteristics and childhood acute leukaemia

The objective of the present study was to investigate the role of early common infections and perinatal characteristics in the aetiology of childhood common leukaemia. A case–control study was conducted from 1995 to 1998 in France, and included 473 incident cases of acute leukaemia (AL) (408 acute lymphoblastic leukaemia (ALL), 65 acute myeloid leukaemia (AML) age-, sex- and region-matched with 567 population-based controls. Data on the medical history of the child and his/her environment were collected using self-administered questionnaires. Analyses were conducted using nonconditional logistic regression. A slight negative association with early infections was observed (OR=0.8; 95% CI (0.6–1.0)). The association was stronger for early gastrointestinal infections. Early day-care was found to be associated with a decreased risk of AL (OR=0.6; 95% CI (0.4–0.8) and OR=0.8; 95% CI (0.5–1.2) for day-care starting before age 3 months and between 3 and 6 months, respectively). No association with breast-feeding was observed, irrespective of its duration. A birth order of 4 or more was associated with a significantly increased risk of AL (OR=2.0; 95% CI (1.1–3.7) with ALL). A history of asthma was associated with a decreased risk of ALL (OR 0.5; 95% CI (0.3–0.90). Although the results regarding birth order and breast-feeding do not fit with Greaves' hypothesis, the study supports the hypothesis that early common infections may play a protective role in the aetiology of childhood leukaemia, although this effect was not more marked for common ALL.