Negative regulation of prophenoloxidase (proPO) activation by a clip-domain serine proteinase homolog (SPH) from endoparasitoid venom

Most parasitic wasps inject maternal factors into the host hemocoel to suppress the host immune system and ensure successful development of their progeny. Melanization is one of the insect defence mechanisms against intruding pathogens or parasites. We previously isolated from the venom of Cotesia rubecula a 50 kDa protein that blocked melanization in the hemolymph of its host, Pieris rapae [Insect Biochem. Mol. Biol. 33 (2003) 1017]. This protein, designated Vn50, is a serine proteinase homolog (SPH) containing an amino-terminal clip domain. In this work, we demonstrated that recombinant Vn50 bound P. rapae hemolymph components that were recognized by antisera to Tenebrio molitor prophenoloxidase (proPO) and Manduca sexta proPO-activating proteinase (PAP). Vn50 is stable in the host hemolymph-it remained intact for at least 72 It after parasitization. Using M. sexta as a model system, we found that Vn50 efficiently down-regulated proPO activation mediated by M. sexta PAP-1, SPH-1, and SPH-2. Vn50 did not inhibit active phenoloxidase (PO) or PAP-1, but it significantly reduced the proteolysis of proPO. If recombinant Vn50 binds P. rapae proPO and PAP (as suggested by the antibody reactions), it is likely that the molecular interactions among M. sexta proPO, PAP-1, and SPHs were impaired by this venom protein. A similar strategy might be employed by C rubecula to negatively impact the proPO activation reaction in its natural host. (C) 2004 Elsevier Ltd. All rights reserved.

Low-complexity low-PAR transmission for MIMO-DSL

This letter considers clip-limited transmission over multiple-input multiple-output digital subscriber lines (MIMO-DSL). We show that a recent low complexity, low peak-to-average-ratio (PAR) single-input modulation technique can be applied to the case of multiple cross-talking channels in a bonded-DSL system. Unfortunately however the direct initialization procedure is computationally infeasible. In this paper, we provide a novel low-complexity initialization procedure. Simulations confirm that the proposed approach has superior performance in clip-limited conditions, compared with both discrete matrix multitone and vectored discrete multitone.

The rellationship between specific features of aphasia-friendly written material and comprehension of written material for people with aphasia: An exploratory study

Background: Written material is often inaccessible fro people with aphasia. The format of written material needs to be adapted to enable people with aphasia to read with understanding. Aims: This study aimed to further explore some issues raised in Rose, Worrall, and MacKenna (2003) concerning the effects of aphasia-friendly formats on the reading comprehension of people with aphasia. It was hypothesised that people with aphasia would comprehend significantly more paragraphs that were formatted in an aphasia-friendly manner than control paragraphs. This study also aimed to investigate if each single aspect of aphasia-friendly formatting (i.e., simplified vocabulary and syntax, large print, increased white spacem and pictures) used in isolation would result in increased comprehension compared to control paragraphs. Other aims were to compare the effect of aphasia-friendly fromatting with the effects of each single adaptation, and to investigate if the effects of aphasia-friendly formates were related to aphasia severity. Methods & Procedures: Participants with mild to moderately severe aphasia (N = 9) read a battery of 90 paragraphs and selected the best word of phrase from a choice of four to complete each paragraph. A linear mixed model (p < .05) was used to analyse the differences in reading comprehension with each paragraph fromat across three reading grade levels. Outcomes & Results: People with aphasia comprehended significantly more aphasia-friendly paragraphs than control paragraphs. They also comprehended significantly more paragraphs with each of the following single adaptations: simplified vocabulary and syntax, large ptint, and increased white spaces. Although people with aphasia tended to comprehend more paragraphs with pictures added than control paragraphs, this difference was not significant. No significant correlation between aphasia severity and the effect of aphasia-friendly formatting was found. Conclusion: This study supports the idea that aphasia-friendly formats increase the reading comprehension of people with aphasia. It suggests that adding pictures, particularly Clip Art pictures, may not significantly improve the reading the reading comprehension of people with aphasia. These findings have implications for all written communication with people with aphasia, both in the clinical setting and in the wider community. Applying these findings may enable people with aphasia to have equal access to written information and to participate in society.

Hierarchical indexing structure for efficient similarity search in video retrieval

With the rapid increase in both centralized video archives and distributed WWW video resources, content-based video retrieval is gaining its importance. To support such applications efficiently, content-based video indexing must be addressed. Typically, each video is represented by a sequence of frames. Due to the high dimensionality of frame representation and the large number of frames, video indexing introduces an additional degree of complexity. In this paper, we address the problem of content-based video indexing and propose an efficient solution, called the Ordered VA-File (OVA-File) based on the VA-file. OVA-File is a hierarchical structure and has two novel features: 1) partitioning the whole file into slices such that only a small number of slices are accessed and checked during k Nearest Neighbor (kNN) search and 2) efficient handling of insertions of new vectors into the OVA-File, such that the average distance between the new vectors and those approximations near that position is minimized. To facilitate a search, we present an efficient approximate kNN algorithm named Ordered VA-LOW (OVA-LOW) based on the proposed OVA-File. OVA-LOW first chooses possible OVA-Slices by ranking the distances between their corresponding centers and the query vector, and then visits all approximations in the selected OVA-Slices to work out approximate kNN. The number of possible OVA-Slices is controlled by a user-defined parameter delta. By adjusting delta, OVA-LOW provides a trade-off between the query cost and the result quality. Query by video clip consisting of multiple frames is also discussed. Extensive experimental studies using real video data sets were conducted and the results showed that our methods can yield a significant speed-up over an existing VA-file-based method and iDistance with high query result quality. Furthermore, by incorporating temporal correlation of video content, our methods achieved much more efficient performance.

Dynamic microtubules regulate the local concentration of E-cadherin at cell-cell contacts

In contrast to the well-established relationship between cadherins and the actin cytoskeleton, the potential link between cadherins and microtubules (MTs) has been less extensively investigated. We now identify a pool of MTs that extend radially into cell-cell contacts and are inhibited by manoeuvres that block the dynamic activity of MT plus-ends (e.g. in the presence of low concentrations of nocodazole and following expression of a CLIP-170 mutant). Blocking dynamic MTs perturbed the ability of cells to concentrate and accumulate E-cadherin at cell-cell contacts, as assessed both by quantitative immunofluorescence microscopy and fluorescence recovery after photobleaching (FRAP) analysis, but did not affect either transport of E-cadherin to the plasma membrane or the amount of E-cadherin expressed at the cell surface. This indicated that dynamic MTs allow cells to concentrate E-cadherin at cell-cell contacts by regulating the regional distribution of E-cadherin once it reaches the cell surface. Importantly, dynamic MTs were necessary for myosin II to accumulate and be activated at cadherin adhesive contacts, a mechanism that supports the focal accumulation of E-cadherin. We propose that this population of MTs represents a novel form of cadherin-MT cooperation, where cadherin adhesions recruit dynamic MTs that, in turn, support the local concentration of cadherin molecules by regulating myosin II activity at cell-cell contacts.

Phacoemulsification in anterior megalophthalmos

This case outlines the phacoemulsification technique used to overcome the challenge of the hyperdeep anterior chamber, weak zonules, abnormal anterior capsule, and large capsular bag. Key steps included trypan blue staining of the anterior capsule, a large capsulorhexis, prolapse of the nucleus into the anterior chamber with phacoemulsification anterior to the capsulorhexis, and a posterior chamber-placed iris-clip intraocular lens. Successful visual rehabilitation is achievable in these anatomically challenging eyes. © 2006 ASCRS and ESCRS.