migration [3]. Due to the inherent ability to utilize the nucleotides and nucleosides as substrate auto- taxin(E-NPP2) act as a positive regulator by termi- nating P2X and P2Y receptor signalling coupled to Ca 2+ -influx, Gi, Gs and Gq proteins [4]. LPC is a free or membrane bound form of lipid(s) which are converted to arachidonic acid (AA) by mem- brane bound phospholipase C and A 2 . AA is a sub- strate for the lipoxygenase pathway forming LTB 4 (Leukotriene B 4 ). LTB 4 has been hypothesized as an essential metabolic intermediate in the extra- cellular nucleotide-induced overexpression of inte- grins [5]. In the context of the proposed hypotheses, it is essential to point out that both LPC-mediated sig- naling and extracellular nucleotide-induced signaling transpire via LTB 4 -mediated events con- verging on the mitogen activated protein kinases (MAPK) pathway. It is suggested that it is a cumu- lative effect that mediate the overexpression of the integrin(s) on the neutrophil membrane. Spe- cific type of integrins has also been shown to mediate the signaling cascade via PI3Kinase, fol- lowed by one or more pathways converging on MAPKs for activation and secretion of autotaxin [6]. In summary, the ATX extracellularly attenu- ate the purine/pyrimidine signaling, but exacer- bate inflammation by upregulating the integrins on neutrophil membrane via LTB 4 for augmenting chemotaxis. References [1] Clair T, Lee HY, Liotta LA, Stracke ML. Autotaxin is an exoenzyme possessing 5 0 -nucleotide phosphodiesterase/ATP pyrophosphatase and ATPase activities. J Biol Chem 1997;272:996–1001. [2] Tokumura A, Majima E, Kariya Y, Tominaga K, Kogure K, Yasuda K et al. Identification of human plasma lysophos- pholipase D, a lysophosphatidic acid-producing enzyme, as autotaxin, a multifunctional phosphodiesterase. J Biol Chem 2002;277:39436–42. [3] Mills GB, Moolenaar WH. The emerging role of lysophospha- tidic acid in cancer. Nat Rev Cancer 2003;8:582–91. [4] Goding JW, Grobben B, Slegers H. Physiological and path- ophysiological functions of the ecto-nucleotide pyrophos- phatase/phosphodiesterase family. Biochim Biophys Acta 2003;1638:1–19. [5] Kannan S. Neutrophil chemotaxis: potential role of chemo- kine receptors in extracellular nucleotide induced Mac-1 expression. Med Hypotheses 2003;61:577–9. [6] Jauliac S, Lopez-Rodriguez C, Shaw LM, Brown LF, Rao A, Toker A. The role of NFAT transcription factors in integrin- mediated carcinoma invasion. Nat Cell Biol 2002;4:540–544. Subburaj Kannan DNA Repair and Drug Resistance Group Departments of Microbiology and Immunology School of Medicine University of Texas Medical Branch Galveston, TX 77555, US Tel.: +1 409 750 9060 E-mail address: sukannan@utmb.edu skannan22@hotmail.com doi:10.1016/j.mehy.2005.01.001 Nanotechnology helps medicine: Nanoscale swimmers and their future applications Delivering materials towards their targets and per- forming very accurate manipulations using a safe and rapid method inside the human body has been challenging for years. The idea of using very small devices capable of moving within the biological flu- ids seemed promising, even before the word ‘‘nanotechnology’’ ever existed. To get moving, small living organisms use flagel- lum or whip-like drive. Unfortunately, molecular engineering of such devices are intricate. Recently, a simple nano-swimmer model is introduced [1], which proposes a sphere-end-rod device that swims like an earthworm by contracting and expanding in one dimension, and should be easy to manufacture as technical difficulties of such nanoscale construc- tions are declining. It is not unreal to imagine such tools as the first generation of produced nano-swimmers. Combination of nano-computers with these devices can also be an important milestone: Nano-computers would be able to monitor the body conditions [2], and in case of any deficiencies nano- swimmers would be sent as messengers of the com- puters with the ability of functioning at the ailing site. One possible application of these swimmers might be in delivering drugs inside the body. For example, these swimmers may deliver cancer- fighting agents directly to tumors. This might de- crease the drug side-effects significantly, as the 198 Correspondence