The AMICUS system was recently introduced for peripheral blood stem cell (PBSC) aphereses in adults. We conducted a single center field evaluation to obtain data about the performance of this system in children with a body weight (bw) < 25 kg. Results of blood priming procedures were compared to historical data obtained with the Fenwal CS3000+ (CS 3000). From August, 2001 to February, 2007, 47/178 (26%) PBSC aphereses procedures were performed in our institution with the AMICUS system in 35 small patients (median bw 13.9 kg; range 6.7-24; age 2.78 years; range 0.97-7.06). The patients suffered from various malignant primary diseases or recurrences. We primed the system with packed RBC in case of >30% dilution of the RBC volume (n = 31) or with saline (n = 16). Compared to the CS3000, the AMICUS revealed comparable collection efficiencies (CE) for CD34+ cells (median 67%, range 26-120), lymphocytes (75%, 25-138), monocytes (54%, 23-173), and granulocytes (10%, 1.5-36), MNC (57% 24-125), but a significantly higher erythrocyte and granulocyte, and a lower platelet CE. There was a significant negative correlation between total leukocyte count and CE for MNC (r = -0.566; P < 0.001) and CD34+ cells (r = -0.517; P < 0.001). There was no significant statistical or clinical difference between the CE in blood-primed procedures and saline-primed procedures. With the AMICUS we saw statistically less citrate reactions compared to the CS 3000. We conclude that the AMICUS system is safe and efficient to harvest PBSC on a routine basis in pediatric patients, even in children < or =10 kg bw.

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Like other lithio derivatives of thioacetals bearing a second anionic site, dilithio derivatives of 3,3-, 5 5 , and 6,6-bis(phenylthio) alcohols decompose at or below ambient temperature to yield products ascribable to carbenoid intermediates. The 5,5-derivatives decompose far faster than the other types, and they yield mainly 2-(phenylthio)cyclopentanols and none of the unsaturated alcohols and glycols, arising from 1,2-hydrogen transfer and carbenoid dimerization, respectively, which are the major products from the other two types of reactants. The five-membered ring formation observed in the 5,5-systems results from insertion of a carbenoid carbon atom into the activated carbinol CH bond of the oxyanion, and a stereochemical study reveals that this process is not concerted. The evidence suggests that this ring closure is a result of displacement of a thiophenoxide ion from the lithiothioacetal by a hydride ion which is transferred from the carbinyl carbon atom in a transition state involving coordination of the lithium atom of the carbenoid with the oxyanion.Recently, we proposed the following principle which has led A. J. Am. Chem. Soc. 1973, 95,4100. Brown, H. C.; Krishnamurthy, S. J. J. Am. Chem. Soc. 1972,94,7159. (12) Consistent with literature precedents, 23 and 21 were produced in a ratio of 2.6:l; for example, see: Dauben, W. G.; Fonkcn, G. J.; Noyce, D. S. J. Am. Chem. Soc. 1956, 78, 2519. (13) Mura, A. J., Jr.; Majetich, P. A.; G r i m , P. A.; Cohen, T. Tetrahedron Lett. 1975, 4431. (14) The major product of treatment of the cis-cyclohexanol mixture 21 with excess HCl and 1.5 quiv of thiophenol for 20 h was the octahydrochromene resulting from intramolecular attack of the hydroxyl group on the cation produced by protonation of the vinyl sulfide group, but, as expected, (see, for example, Scheme HI) further treatment of this material led to the monocyclic thioacetal in good yield. An analogous product was formed from 23 along with a much larger amount of 24 after a 5-h treatment with HCI in neat thiophenol (40 quiv). (15) (a) Crandall, J. K.; Magha, H. S. J. Org. Chem. 1982,47,5368. (b) Crandall, J. K.; Magha, H. S.; Henderson, M. A,; Widner, R. K.; Tharp, G.

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