Synthesis and biological activity of novel thiazolidinediones

Novel compounds having a dual pharmacophore were synthesised and evaluated for their insulin sensitiser and anti-inflammatory properties in different animal models.     

Expandable metal stents for the treatment of colonic obstruction: techniques and outcomes

Modulation of CD8(+) T-cell responses specific for an exogenous antigen by epitope variants would be advantageous to develop a novel means of antigen-specific immune regulation. We have analyzed CD8(+) T-cell responses to single amino acid-substituted variants of a peptide corresponding to residues 142-149 (p142-149; LAYFYPEL) of alphas1-casein, a major milk allergen, which is a dominant determinant restricted by H-2Kb. An analog peptide L142I with a substitution of Ile for Leu at the nonanchor N-terminal residue induced more IFN-gamma secretion than p142-149 from specific CD8(+) T cells. Furthermore, L142I could prime CD8(+) T cells more efficiently in vivo, and these L142I-primed cells secreted more IFN-gamma than p142-149-primed CD8(+) T cells upon stimulation with p142-149 in vitro. These findings are mainly explained by the greater ability of L142I to form stable Kb-peptide complexes. These findings indicate that appropriate analog peptides may be useful as efficient inducers of CD8(+) T cells which recognize the parent peptide and secrete IFN-gamma, a potent inhibitor of Th2-dependent events, including IgE production.     

Swelling detection for volume regulation in the primitive eukaryote Giardia intestinalis: a common feature of volume detection in present-day eukaryotes

Interleukin (IL)-12, a natural killer (NK) cell stimulatory factor, is a heterodimeric cytokine that is known to be a potent activator of non-major histocompatibility complex-restricted cytotoxicity by peripheral blood-derived NK cells. NK cells (CD3-CD16+/CD56+) represent approximately 15% of human umbilical cord blood mononuclear cells (HUCB MNCs) and are known to be highly sensitive to activation by IL-2. In the present study, we monitored the effect of IL-12 on the cytotoxic activity, proliferation, and phenotypic expression of HUCB-derived resting and IL-2-activated cytotoxic cells and compared these parameters with those of bone marrow (BM)-derived cells. Lymphocytes were separated from HUCB by 3% gelatin sedimentation and incubated with IL-12 and/or IL-2 for 18 hours. At effector:target ratios of 40:1 and 20:1, IL-12 (50 U/mL) significantly increased both resting and IL-2-activated NK cell-mediated cytotoxicity in a standard 51Cr-release assay against both NK-sensitive (K562) and NK-resistant (Colo-205) cell lines. In addition, resting and IL-2-activated cytotoxic cells derived from HUCB exhibited superior cytolytic ability compared with BM-derived cells. This increase was observed in resting cells as well as in those that were preincubated with IL-12. Moreover, HUCB-derived cells were found to be more sensitive to IL-12 activation than cytotoxic cells from BM. To evaluate the involvement of accessory cells, NK cells were purified from HUCB using immunomagnetic beads, and these cells were found to have a lower response to treatment with IL-12 than unpurified populations. HUCB MNCs exhibited a nonsignificant increase in proliferation after IL-12 treatment and were better able to respond to IL-12 activation than BM MNCs. Following an 18-hour incubation, IL-12 was able to cause upregulation of CD25 and CD69 activation antigens, whereas no significant change in expression of CD16 and CD56 NK cell surface antigens, CD3 on T cells, or IL-12 receptor was observed. Similarly, IL-12 did not affect NK cell:target cell conjugation as assessed by fluorescence-activated cell sorting. Our results indicate that HUCB-derived NK-mediated cytotoxic capabilities can be increased by IL-12, a finding that may have clinical relevance.     

Prostaglandins suppress an outward potassium current in embryonic rat sensory neurons

One of the challenges in understanding ciliary and flagellar motility is determining the mechanisms that locally regulate dynein-driven microtubule sliding. Our recent studies demonstrated that microtubule sliding, in Chlamydomonas flagella, is regulated by phosphorylation. However, the regulatory proteins remain unknown. Here we identify the 138-kD intermediate chain of inner arm dynein I1 as the critical phosphoprotein required for regulation of motility. This conclusion is founded on the results of three different experimental approaches. First, genetic analysis and functional assays revealed that regulation of microtubule sliding, by phosphorylation, requires inner arm dynein I1. Second, in vitro phosphorylation indicated the 138-kD intermediate chain of I1 is the only phosphorylated subunit. Third, in vitro reconstitution demonstrated that phosphorylation and dephosphorylation of the 138-kD intermediate chain inhibits and restores wild-type microtubule sliding, respectively. We conclude that change in phosphorylation of the 138-kD intermediate chain of I1 regulates dynein-driven microtubule sliding. Moreover, based on these and other data, we predict that regulation of I1 activity is involved in modulation of flagellar waveform.     

Structural effects of the binding of GTP to the wild-type and oncogenic forms of the ras-gene-encoded p21 proteins

Molecular dynamics calculations have been performed to determine the average structures of ras-gene-encoded p21 proteins bound to GTP, i.e., the normal (wild-type) protein and two oncogenic forms of this protein, the Val 12- and Leu 61-p21 proteins. We find that the average structures for all of these proteins exhibit low coordinate fluctuations (which are highest for the normal protein), indicating convergence to specific structures. From previous dynamics calculations of the average structures of these proteins bound to GDP, major regional differences were found among these proteins [Monaco et al. (1995), J. Protein Chem., in press]. We now find that the average structures of the oncogenic proteins are more similar to one another when the proteins are bound to GTP than when they are bound to GDP [Monaco et al. (1995), J. Protein Chem., in press]. However, they still differ in structure at specific amino acid residues rather than in whole regions, in contradistinction to the results found for the p21-GDP complexes. Two exceptions are the regions 25-32, in an alpha-helical region, and 97-110. The two oncogenic (Val 12- and Leu 61-) proteins have similar structures which differ significantly in the region of residues 97-110. This region has recently been identified as being critical in the interaction of p21 with kinase target proteins. The differences in structure between the oncogenic proteins suggest the existence of more than one oncogenic form of the p21 protein that can activate different signaling pathways.     

Sleep and nitric oxide: effects of 7-nitro indazole, inhibitor of brain nitric oxide synthase

The in vitro amplification method for heterologous gene expression in mammalian cells is based on the stable transfection of cells with long, linear DNA molecules having several copies of complete expression units, coding for the gene of interest, linked to one terminal unit, coding for the selectable marker. DNA concatenamers containing additional expression units can also be prepared: we exploited this feature by co-polymerizing expression units coding for granulocyte colony-stimulating factor (G-CSF) with cassettes for dihydrofolate reductase (DHFR) and for neomycin (Nm) resistance, as selectable markers. We were thus able to obtain high level production of G-CSF in chinese hamster ovary (CHO) dhfr- cells by combining in vitro amplification to just one step of in vivo amplification. This approach required a considerably shorter time than the classical, stepwise amplification by methotrexate.     

Discrepancies in normative data between Lunar and Hologic DXA systems

Many studies have shown the high correlation between Lunar and Hologic DXA bone mineral density (BMD) measurements despite differences in absolute calibration. However, in clinical practice, raw BMD values (in g/cm2) are not normally used for assessing skeletal status and fracture risk. Instead, the BMD values are expressed in terms of the number of standard deviations above or below the young normal value (commonly referred to as the T-score). If the normative populations of the various systems are consistent, the standard deviation scores should also be consistent. For this reason, the World Health Organization (WHO) recently established diagnostic criteria for osteoporosis based on T-scores and not BMD. However, few studies have compared the instruments in terms of their standard deviation scores. In this study, we used linear regression to compare T-scores in 83 women at L1-4 and 120 women at the femoral neck obtained on a Lunar DPX and a Hologic QDR-1000/W system. patient BMD and T-score measurements were highly correlated between the two systems (r > 0.95). No clinically significant difference in L1-4 T-scores was seen (less than 0.1 SD). However, linear regression analysis confirmed a systematic difference of 0.9 SD between the femoral neck T-scores. This discrepancy is caused by: (1) differences in the normal populations, and (2) differences in statistical models used to determine the young normal mean and standard deviation. In an attempt to correct the discrepancy, the female young normal mean and standard deviation were recalculated for the femoral neck using published epidemiological data from NHANES and existing DXA cross-calibration equations. The Hologic young normal value (mean +/- SD) was redefined as 0.85 +/- 0.11 g/cm2, while the Lunar value was redefined as 1.00 +/- 0.11 g/cm2. When the femoral neck T-scores for the study population were recalculated on the basis of these new values, the results were equivalent between manufactures, effectively eliminating the discrepancy. However, the revised values should be confirmed by additional measurements in young normal adults.