Site-specific effects of peptide lipidation on beta-amyloid aggregation and cytotoxicity

Beta-amyloid (Abeta) aggregates at low concentrations in vivo, and this may involve covalently modified forms of these peptides. Modification of Abeta by 4-hydroxynonenal (4-HNE) initially increases the hydrophobicity of these peptides and subsequently leads to additional reactions, such as peptide cross-linking. To model these initial events, without confounding effects of subsequent reactions, we modified Abeta at each of its amino groups using a chemically simpler, close analogue of 4-HNE, the octanoyl group: K16-octanoic acid (OA)-Abeta, K28-OA-Abeta, and Nalpha-OA-Abeta. Octanoylation of these sites on Abeta-(1-40) had strikingly different effects on fibril formation. K16-OA-Abeta and K28-OA-Abeta, but not Nalpha-OA-Abeta, had increased propensity to aggregate. The type of aggregate (electron microscopic appearance) differed with the site of modification. The ability of octanoyl-Abeta peptides to cross-seed solutions of Abeta was the inverse of their ability to form fibrils on their own (i.e. Abeta approximately Nalpha-OA-Abeta>K16-OA-Abeta>K28-OA-Abeta). By CD spectroscopy, K16-OA-Abeta and K28-OA-Abeta had increased beta-sheet propensity compared with Abeta-(1-40) or Nalpha-OA-Abeta. K16-OA-Abeta and K28-OA-Abeta were more amphiphilic than Abeta-(1-40) or Nalpha-OA-Abeta, as shown by lower "critical micelle concentrations" and higher monolayer collapse pressures. Finally, K16-OA-Abeta and K28-OA-Abeta are much more cytotoxic to N2A cells than Abeta-(1-40) or Nalpha-OA-Abeta. The greater cytotoxicity of K16-OA-Abeta and K28-OA-Abeta may reflect their greater amphiphilicity. We conclude that lipidation can make Abeta more prone to aggregation and more cytotoxic, but these effects are highly site-specific.     

Olfactory Bulb Excitotoxicity as a Gap-Filling Mechanism Underlying the Link Between Traumatic Brain Injury-Induced Secondary Neuronal Degeneration and Parkinson’s Disease-Like Pathology

Neurochemical Research - There is increasing preclinical and clinical data supporting a potential association between Traumatic Brain Injury (TBI) and Parkinson’s disease (PD). It has been...     

Protective immunosurveillance and therapeutic antitumor activity of gammadelta T cells demonstrated in a mouse model of prostate cancer

In contrast to Ag-specific alphabeta T cells, gammadelta T cells can kill malignantly transformed cells in a manner that does not require the recognition of tumor-specific Ags. Although such observations have contributed to the emerging view that gammadelta T cells provide protective innate immunosurveillance against certain malignancies, particularly those of epithelial origin, they also provide a rationale for developing novel clinical approaches to exploit the innate antitumor properties of gammadelta T cells for the treatment of cancer. Using TRAMP, a transgenic mouse model of prostate cancer, proof-of-concept studies were performed to first establish that gammadelta T cells can indeed provide protective immunosurveillance against spontaneously arising mouse prostate cancer. TRAMP mice, which predictably develop prostate adenocarcinoma, were backcrossed with gammadelta T cell-deficient mice (TCRdelta(-/-) mice) yielding TRAMP x TCRdelta(-/-) mice, a proportion of which developed more extensive disease compared with control TRAMP mice. By extension, these findings were then used as a rationale for developing an adoptive immunotherapy model for treating prostate cancer. Using TRAMP-C2 cells derived from TRAMP mice (C57BL/6 genetic background), disease was first established in otherwise healthy wild-type C57BL/6 mice. In models of localized and disseminated disease, tumor-bearing mice treated i.v. with supraphysiological numbers of syngeneic gammadelta T cells (C57BL/6-derived) developed measurably less disease compared with untreated mice. Disease-bearing mice treated i.v. with gammadelta T cells also displayed superior survival compared with untreated mice. These findings provide a biological rationale for clinical trials designed to adoptively transfer ex vivo expanded autologous gammadelta T cells for the treatment of prostate cancer.     

Bethesda 2001. Impact on the reporting of gynecologic cytology

OBJECTIVE: To examine the impact of implementing Bethesda 2001 in one laboratory. STUDY DESIGN: A computer search identified all cervicovaginal specimens evaluated between July 2001 and June 2002. Bethesda 2001 was implemented on January 1, 2002. The rates of specimen adequacy and the frequency of each diagnostic category 6 months before and 6 months after the implementation of Bethesda 2001 were compared. RESULTS: A total of 21,332 cervicovaginal specimens were evaluated during the study period. During the first 6 months, 10,695 specimens were examined; 40% were liquid-based preparations. During the next 6 months, 10,367 specimens were examined; 60% were liquid-based preparations. Prior to the implementation of Bethesda 2001, the percentages of each category were as follows: 74.99% within normal limits, 7.10% reactive/reparative cellular changes (R/R), 10.29% atypical squamous cells (ASC), 0.24% atypical glandular cells (AGC), 3.45% low grade squamous intraepithelial lesion (LSIL), 3.44% high grade squamous intraepithelial lesion (HSIL) and 0.73% unsatisfactory. In addition, 19.00% were classified as "satisfactory but limited by" (SBLB). Following the implementation of Bethesda 2001, the percentages of each category were as follows: 80.09% negative for intraepithelial lesion and malignancy including 6.94% with the qualifier R/R, 10.32% ASC, 0.27% AGC, 4.54% LSIL, 3.44% HSIL and 0.81% unsatisfactory. In addition, 17.40% were satisfactory with a quality indicator (SAT with QI). The incidence of reporting benign endometrial cells in patients over age 40 was the same for both periods. There was a significant decrease in the percentage of specimens classified as SAT with QI when compared to that of specimens classified as SBLB. A statistically significant increase in the percentage of specimens was noted in the category LSIL (P < or = .001) and satisfactory (.005) after implementing Bethesda 2001. No significant changes were noted in other categories. CONCLUSION: Our laboratory experienced some changes in the laboratory statistics of reporting gynecologic cytology after the implementation of Bethesda 2001. Continuous monitoring of reporting trends is indicated to clearly understand the impact of Bethesda 2001 on laboratory statistics.     

Purification and characterization of 4-N-trimethylamino-1-butanol dehydrogenase from Fusarium merismoides var. acetilereum

From investigation of 60 filamentous fungi, we identified Fusarium merismoides var. acetilereum, which uses 4-N-trimethylamino-1-butanol (TMA-butanol) as the sole source of carbon and nitrogen. The fungus produced NAD⁺-dependent TMA-butanol dehydrogenase (DH) when it was cultivated in medium containing TMA-butanol. The enzyme showed molecular mass of 40 kDa by SDS–PAGE and 160 kDa by gel filtration, suggesting that it is a homotetramer. TMA-butanol DH is stable at pH 7.5–9.0. It exhibits moderate stability with respect to temperature (up to 30 °C). Additionally, it has optimum activity at 45 °C and at pH 9.5. The enzyme has broad specificity to various alkyl alcohols and amino alkyl alcohols, and the carbon chains of which are longer than butanol. Moreover, the activity is strongly inhibited by oxidizing agents, carbonyl and thiol modulators, and chelating agents. This report is the first study examining TMA-butanol DH from eukaryotic microbes.     

Absence of innate MyD88 signaling promotes inducible allograft acceptance

Prior experimental strategies to induce transplantation tolerance have focused largely on modifying adaptive immunity. However, less is known concerning the role of innate immune signaling in the induction of transplantation tolerance. Using a highly immunogenic murine skin transplant model that resists transplantation tolerance induction when innate immunity is preserved, we show that absence of MyD88, a key innate Toll like receptor signal adaptor, abrogates this resistance and facilitates inducible allograft acceptance. In our model, absence of MyD88 impairs inflammatory dendritic cell responses that reduce T cell activation. This effect increases T cell susceptibility to suppression mediated by CD4+ CD25+ regulatory T cells. Therefore, this study provides evidence that absence of MyD88 promotes inducible allograft acceptance and implies that inhibiting innate immunity may be a potential, clinically relevant strategy to facilitate transplantation tolerance.