Trypanosoma brucei Modifies the Tsetse Salivary Composition, Altering the Fly Feeding Behavior That Favors Parasite Transmission

Tsetse flies are the notorious transmitters of African trypanosomiasis, a disease caused by the Trypanosoma parasite that affects humans and livestock on the African continent. Metacyclic infection rates in natural tsetse populations with Trypanosoma brucei, including the two human-pathogenic subspecies, are very low, even in epidemic situations. Therefore, the infected fly/host contact frequency is a key determinant of the transmission dynamics. As an obligate blood feeder, tsetse flies rely on their complex salivary potion to inhibit host haemostatic reactions ensuring an efficient feeding. The results of this experimental study suggest that the parasite might promote its transmission through manipulation of the tsetse feeding behavior by modifying the saliva composition. Indeed, salivary gland Trypanosoma brucei-infected flies display a significantly prolonged feeding time, thereby enhancing the likelihood of infecting multiple hosts during the process of a single blood meal cycle. Comparison of the two major anti-haemostatic activities i.e. anti-platelet aggregation and anti-coagulation activity in these flies versus non-infected tsetse flies demonstrates a significant suppression of these activities as a result of the trypanosome-infection status. This effect was mainly related to the parasite-induced reduction in salivary gland gene transcription, resulting in a strong decrease in protein content and related biological activities. Additionally, the anti-thrombin activity and inhibition of thrombin-induced coagulation was even more severely hampered as a result of the trypanosome infection. Indeed, while naive tsetse saliva strongly inhibited human thrombin activity and thrombin-induced blood coagulation, saliva from T. brucei-infected flies showed a significantly enhanced thrombinase activity resulting in a far less potent anti-coagulation activity. These data clearly provide evidence for a trypanosome-mediated modification of the tsetse salivary composition that results in a drastically reduced anti-haemostatic potential and a hampered feeding performance which could lead to an increase of the vector/host contact and parasite transmission in field conditions

New technologies in surgery

The progress of technology and robotics in industry has not yield to an equivalent development in the medical field. This paper analyses surgical proce-dures from the point of view of industrial processes looking for analogies in both fields so as to evaluate the possibilities of using equivalent technologies in both of them. After analyzing surgical specialties from the mechanical point of view, the actions to be performed, and the main requirements as precision and working conditions, a look at the main challenges that surgical robotics should face is presented.Peer ReviewedPostprint (published version

A Multistage Registration Method Using Texture Features

We present a novel, multistage registration method based on Laws’ texture features. In general, a large number of texture features may be extracted from the original intensity images. For each of the texture features, a criterion function that measures the similarity between the images may be derived. The proposed registration method consists of two major steps. In the first step, a dataset of images with the corresponding gold standard is used. In this step, the selection and ranking of the texture features for registration is made. The selection and ranking of the features is based on their robustness, accuracy, and capture range. The selected features are then entered in the second step, where the actual registration is performed using a sequence of registration stages. Our method is based on the selection of the most robust feature for the first registration stage and the selection of accurate feature(s) for the subsequent stages. The texture features are daisy-chained so that the accuracy of the previous feature is sufficient for the capture range of the next feature. We tested our method on 11 2D image pairs containing digital reconstructed radiographs and electron portal imaging modalities, which were difficult to register using intensity features alone. With our method, we have successfully registered 75% of the initial displacements, ranging from 5 to 7.5 mm, with the target-registration error below 3 mm, whereas the traditional intensity-based approach delivered only 15% successfully registered cases