Docosahexaenoic acid ethyl esters from Isochrysis galbana

In order to produce docosahexaenoic acid (DHA), a culture of the microalgal strain Isochrysis galbana was implemented. In Erlenmeyer flasks, a natural seawater medium, the Provasoli 1/3 medium, was compared to the classical Jones medium for DHA production. The Provasoli 1/3 medium stimulated growth (0.44 d(-1)), but influenced DHA accumulation negatively (0.240 pg cell(-1)). However, DHA production per liter of culture medium were of the same order of magnitude with both media (0.961 mg l(-1)). In a 2-l bioreactor, DHA production per liter of culture medium did not increase significantly between 4 and 8 days of culture. With a view to optimize DHA productivity, cells should be harvested at the end of exponential phase i.e. after 4 days of culture. Two strategies were then attempted to produce DHA ethyl esters. First, lipids from I. galbana were submitted to lipase-catalyzed transesterification with ethanol. Secondly, fatty acids from I. galbana were submitted to lipase catalyzed esterification with ethanol. In both cases, lipase from Candida antarctica was shown to be the best candidate, among the five tested, with conversion yields of 20 and 60% after 24 h of transesterification and esterification respectively.

Tandem time-of-flight experiment for low energy collision studies

We present an experiment adapted to collisional studies of cluster ions based on a laser vaporization setup coupled to a supersonic expansion. The ions are selected in a first time-of-flight, slowed down to the desired energy, and collided in an octopolar guide. The parent and fragment ions are then reaccelerated in order to be mass analyzed in a reflectron time-of-flight. An original method for the extraction of the ion that uses a double voltage pulse, is proposed. The experiment has been applied to collisions of hydrated cobalt ions. An absolute cross section of 17 A2 for the loss of one water molecule by Co(H2O)2+ in collision with neon at a center-of-mass energy of 10 eV, has been determined, with an accuracy of 10%. The threshold for this reaction has been measured at 1.5 eV and is in good agreement with the existing literature (Dalleska et al. J. Am. Chem. Soc. 1994, 116, 3519). Ions that cannot be formed by conventional ligand exchange methods, can also be studied. As an example, the threshold for dehydration of the Co2(H2O)+ ion has been measured at 1.5 +/- 0.2 eV.

Crucial role of the interleukin 1 receptor family member T1/ST2 in T helper cell type 2-mediated lung mucosal immune responses

T1/ST2 is an orphan receptor of unknown function that is expressed on the surface of murine T helper cell type 2 (Th2), but not Th1 effector cells. In vitro blockade of T1/ST2 signaling with an immunoglobulin (Ig) fusion protein suppresses both differentiation to and activation of Th2, but not Th1 effector populations. In a nascent Th2-dominated response, anti-T1/ST2 monoclonal antibody (mAb) inhibited eosinophil infiltration, interleukin 5 secretion, and IgE production. To determine if these effects were mediated by a direct effect on Th2 cells, we next used a murine adoptive transfer model of Th1- and Th2-mediated lung mucosal immune responses. Administration of either T1/ST2 mAb or T1/ST2-Ig abrogated Th2 cytokine production in vivo and the induction of an eosinophilic inflammatory response, but failed to modify Th1-mediated inflammation. Taken together, our data demonstrate an important role of T1/ST2 in Th2-mediated inflammatory responses and suggest that T1/ST2 may prove to be a novel target for the selective suppression of Th2 immune responses.

Multiple pigmented cutaneous papules associated with a novel canine papillomavirus in an immunosuppressed dog

Cutaneous papillomavirus infection was diagnosed in a 6-year-old female Boxer dog that was under long-term corticosteroid therapy for atopic dermatitis. Multiple black, rounded papules were present on the ventral skin. Spontaneous regression occurred within 3 weeks after cessation of corticosteroids. Histologically, the lesions consisted of well-demarcated cup-shaped foci of epidermal endophytic hyperplasia with marked parakeratosis. In the upper stratum spinosum and in the stratum granulosum, solitary or small collections of enlarged keratinocytes were observed with basophilic intranuclear inclusion bodies and a single eosinophilic fibrillar cytoplasmic inclusion. Ultrastructurally, viruslike particles (40-45 nm in diameter) were observed within the nucleus, free or aggregated in crystalline arrays. Undulating fibrillar material, thought to be a modified keratin protein, was observed in the cytoplasmic inclusion. Immunohistochemistry, restriction enzyme analysis, and molecular hybridization experiments indicated that these distinctive clinical, histologic, and cytologic features were associated with a novel canine papillomavirus.

Interleukin 2 (IL-2) receptor expression and sensitivity to diphteria fusion toxin DAB389IL-2 in cultured hematopoietic cells

The high-affinity interleukin 2 (IL-2) receptor is a heterotrimer consisting of alpha, beta, and gamma subunits. We examined the concentration of subunit mRNA for each of the three protein subunits on human hematopoietic cell lines, human peripheral blood mononuclear cells, and murine fibroblasts transfected with cDNAs encoding the human IL-2 receptor subunits. In most cultured hematopoietic cells, there was abundant gamma subunit message. In contrast, there was variable expression of both alpha and beta subunit message. Sensitivity of cells to the diphtheria fusion toxin DAB389IL-2 was not related to expression of any single IL-2 receptor subunit mRNA. Rather, the greatest sensitivity was observed for cells possessing all three subunit mRNAs. Cells displaying beta and gamma subunit mRNA showed a reduced but significant sensitivity to the fusion toxin. In contrast, cells with alpha and gamma subunit mRNA, but missing the beta subunit mRNA, were insensitive to DAB389IL-2. The data correlate with the requirement for an intermediate or a high-affinity receptor for cell intoxication. A critical concentration of the beta subunit may be required for toxin internalization and killing.

Measurement of intracellular pH in cultured cells by flow cytometry with BCECF-AM

This study evaluates the suitability of flow cytometry with the fluorochrome BCECF for measuring the intracellular pH (pHi) of cultured cells, and monitors the changes in pHi in murine hybridoma in batch culture and chick embryo fibroblast in monolayer culture (5th passage). The technique produced highly reproducible, repeatable results. The theoretical sensitivity from the calibration curve was 0.0004 pH units. But analysis of the standard deviation of the histogram of the green/red fluorescence ratios indicated a mean sensitivity of 0.08 (0.07-0.09) pH units. Interference due to cell size, fluorochrome incorporation and esterases were minimized by establishing a calibration curve with the cells whose pHi was to be measured using the 525/610 nm fluorescence ratio after excitation at 488 nm. The pHi of exponentially growing, batch cultured hybridomas was 7.50 at the start of culture. pHi increased during the exponential growth phase and dropped towards cell death. The pHi of the chick fibroblasts in monolayer culture was 7.30.

Natural killer cell response to regional lymph node metastases

A determination of natural killer cell activity was performed in 67 individuals with advanced head and neck cancer. The mean activity of 28 patients clinically staged T3 NO or T4 NO was 81 +/- 11 lytic units (LU), significantly higher than 39 patients with palpable lymph node metastases (54 +/- 5 LU). Assessing patients by extent of nodal disease revealed that activity actually increased, though not significantly, with progressive N-staging. A major determinate of increased natural killer cell cytotoxicity in patients with lymph node metastases was extranodal cancer within the neck. The mean activity of nine patients whose tumor was fixed to underlying structures or adherent to skin was 87 +/- 15 LU, significantly higher than the 45 +/- 4 LU mean value of the remaining patients with clinically determined regional nodal disease. The potential clinical implications of these findings are discussed.

Piracetam interactions with neuroleptics in psychopharmacological tests

Two psychopharmacological tests which usually predict neuroleptic activity were conducted after joint administration of piracetam and three neuroleptics (haloperidol, fluphenazine and sulpiride) chosen for their different chemical classes and dopaminergic affinities. In these tests, specific doses of the neuroleptics were used to determine whether piracetam induced potentiation or antagonism of their action. Overall, piracetam increased neuroleptic action regardless of the administration timetable used, but the interaction of fluphenazine differed from that of the other two substances, because piracetam did not modify its action in a specific test of the presynaptic DA-2 dopaminergic receptors. This variation for fluphenazine may be explained by the fact that its pKa value is closer to that of piracetam, thus preventing better bioavailability of the neuroleptic, or its better affinity for DA-1 dopaminergic receptors. Nevertheless, the variation may have been due to a differing affinity for dopaminergic receptors, although this hypothesis is not completely satisfactory because it does not account for differences due to the administration timetable. It is thus suggested that action occurs on nonspecific sites and has the effect of increasing overall neuroleptic bioavailability.