SUMMARYWe use Japanese aggregate and disaggregate money demand data to show that conflicting inferences can arise.The aggregate data appears to support the contention that there was no stable money demand function. The disaggregate data shows that there was a stable money demand function. Neither was there any indication of the presence of a liquidity trap. Possible sources of discrepancy are explored and the diametrically opposite results between the aggregate and disaggregate analysis are attributed to the neglected heterogeneity among micro units. We provide necessary and sufficient conditions for the existence of a cointegrating relation among aggregate variables when heterogeneous cointegration relations among micro units exist. We also conduct simulation analysis to show that when such conditions are violated, it is possible to observe stable micro relations, but unit root phenomena among macro variables. Moreover, the prediction of aggregate outcomes, using aggregate data, is less accurate than the prediction based on micro equations, and policy evaluation based on aggregate data ignoring heterogeneity in micro units can be grossly misleading.

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Summary. The significance of interleukin 6 receptor (IL-6R) expression by cord blood (CB)-and peripheral blood (PB)-derived primitive haematopoietic progenitors was investigated. IL-6R was preferentially expressed by PB-derived myeloid progenitors. Most PB-derived erythroid bursts (BFU-E) and mixed colony-forming cells (CFU-Mix) did not express this receptor. However, CB-derived primitive progenitor cells possessed multipotentiality, irrespective of IL-6R expression. Interestingly, the long-term culture-initiating cell (LTC-IC) population was enriched in PB-derived CD34 1 IL-6R 1 cells, but the extended LTC-IC (ELTC-IC) population, which represents a less mature class of haematopoietic progenitors, seemed to be equally distributed in the IL-6R 1 and IL-6R 2 cell populations. In contrast, the number of LTC-ICs and ELTC-ICs was similar in CB-derived CD34 1 IL-6R 1 or IL-6R 2 cells. It is noteworthy that the number of LTC-ICs and ELTC-ICs in CB-derived CD34 1 cells was markedly higher than that in PB-derived CD34 1 cells regardless of IL-6R expression. Telomerase activity was consistently lower in PB-derived CD34 1 IL-6R 2 cells than in CD34 1 IL-6R 1 cells. In contrast, telomerase activity was similar in CB-derived CD34 1 IL-6R 1 or IL-6R 2 cells. The pattern of telomerase induction upon cytokine stimulation differed between CBand PB-derived CD34 1 IL-6R 1 or IL-6R 2 cells. However, overall telomerase activity per dish was well correlated with the proliferative potential of both cell populations, suggesting that induction of telomerase plays an important role in the escape from replicative senescence of primitive haematopoietic progenitors. Collectively, these results suggest that CB-derived primitive progenitors are less mature than PBderived progenitors and that the expression of IL-6R by primitive haematopoietic progenitors may have different implications for PB-and CB-derived CD34 1 cells.

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