This paper explores the relation between the structured parallelism exposed by the Decomposable BSP (D-BSP) model through submachine locality and locality of reference in multi-level cache hierarchies. Specifically, an efficient cache-oblivious algorithm is developed to simulate D-BSP programs on the Ideal Cache Model (ICM). The effectiveness of the simulation is proved by showing that optimal cache-oblivious algorithms for prominent problems can be obtained from D-BSP algorithms. Finally, a tight relation between optimality in the D-BSP and ICM models is established.

We found the results reported by Lo et al very interesting since their work constitutes a useful complement to our previously published study (Petit et al, 1997). In the latter we were able to detect maternal cells in 8/8 fetal blood samples collected during the third trimester of pregnancy but we could not detect them in the single second-trimester sample that was tested. Lo et al have searched for the presence of maternal cells in five second-trimester samples using allelespecific PCR amplification. Although the authors did not mention the sensitivity limit of their assay, it should be comparable to ours since we both used similar methods. They detected maternal cells in one sample out of five. We believe that their result (1/5) was not significantly different from ours (0/1). Altogether, the results of both studies indicate that transfer of maternal cells into the fetal circulation is probably a rare event during the second trimester of pregnancy but is quite frequent during the third trimester. It might be worth extending the study to a larger sample in order to obtain a statistically significant assessment of the frequency of the phenomenon. We do agree with the conclusion of Lo et al that 'this prenatal cell trafficking is a potential mechanism for the mother to influence the development of the immune system of the fetus'. Laboratoire de Génétique T H I E R RY PETIT MENINGEAL RELAPSE IN A PATIENT WITH ACUTE PROMYELOCYTIC LEUKAEMIA TREATED WITH ALL-TRANS RETINOIC ACIDWe would like to extend the interesting observation of Evans et al (1997) concerning central nervous system (CNS) relapse in acute promyelocytic leukaemia (APL). We recently experienced the occurrence of meningeal relapse in a patient affected with APL in complete clinical-haematological remission after all-trans-retinoic (ATRA) and idarubicin induction therapy according to the AIDA GIMEMA study (Avvisati et al, 1996).The patient, a 50-year-old man, was diagnosed with APL in March 1997. Bone marrow examination showed classic morphological APL. The phenotype was typical for APL except for CD56 positivity (77% of cells). The WBC count was 7·5 × 10 9 /l. The t(15;17) was demonstrated, with a bcr3 PML breakpoint at the molecular level. In April 1997, after induction chemotherapy, a complete morphological remission was obtained. 5 months later the patient complained of headache, vomiting and visual disturbances. The cerebrospinal fluid was infiltrated with 0·7 × 10 9 /l blasts which showed a bcr3 PML breakpoint; CNS MNR was normal. Bone marrow examination showed a morphological complete remission status with persistence of the same molecular lesion. The patient received intrathecal methotrexate and ARA-C and systemic chemotherapy with high-dose ARA-C followed by mitoxantrone, VP 16 and standard-dose ARA-C. He is now in CNS and bone marrow remission.The present report raises the question whether the use of ATRA therapy increases the incidence of either CNS involvement or unusual sites of relapse in APL. In addition to those of Evans et al (1997) and...

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Neuroendocrine tumors are rare and slow-growing neoplasias derived from neuroendocrine cells, which are present throughout the body; they arise especially in the bronchopulmonary system but they have been described also in many extrapulmonary sites including gastrointestinal tract, prostate, bladder, ovary and cervices. Small cell neuroendocrine carcinoma (SCNC) of the breast is rare, accounting for less than 0.1% of all breast cancers and less than 1% of all neuroendocrine tumors [1, 2]. To our knowledge, only about 30 cases have been reported in the English literature since the first case reported in 1983 [3]. We present two cases of primary SCNC of the breast and discuss the clinical, radiological and pathological manifestation. Case report Case one A 38 year-old woman had presented for two months a painless mass in the right breast. Clinical investigation revealed no palpable axillary lymph nodes; she had no