Thomas S. Ellis

Nitric oxide production by coelomocytes of Asterias forbesi.

Vertebrate mononuclear phagocytes produce a plethora of molecules involved in host defense. Among the most potent are the reactive oxygen and nitrogen intermediates. Coelomocytes from invertebrates subserve many of the same functions. In order to determine whether invertebrate phagocytes employ reactive nitrogen intermediates, we investigated the effect of various nonspecific stimulators and invertebrate interleukin (IL)-1alpha- and beta-like molecules on nitric oxide (NO) production. Elevated NO release by stimulated coelomocytes was seen after 24 h. Incubation of stimulated coelomocytes in the presence of arginine analogs inhibited NO release. When invertebrate IL-1-like molecules were added to the coelomocytes, they stimulated the release of NO. Western blot analysis using a polyclonal rabbit antiserum to murine NO synthase detected a band at approximately 125 kDa. These data indicate that coelomocytes are capable of producing and releasing NO and that NO is a chemical mediator that has been conserved as a host defense weapon of phagocytes through evolutionary time.

The Effect of Sample Temperature Gradients on DSC Thermograms at the Glass Transition Temperature

Differential scanning calorimetry is currently being applied with increasing frequency to relatively heavy, and thus thick, samples of a variety of thermally insulating materials.1 Rationale for such applications are, for example, to reduce noise in measurements of small specific heat changes at the glass transition or to reduce, during measurement, the effects of ongoing processes such as the evaporation of plasticizer. As is shown below, however, surprisingly large temperature gradients typically occur in samples of this kind and, although these gradients do not usually affect the determination of specific heat by differential scanning calorimetry, at the glass transition these large gradients do, in fact, mask the true specific heat variation with temperature.