On the biological relevance of MHC class II and B7 expression by tumour cells in melanoma metastases

A large number of studies have indicated that specific immune reactivity plays a crucial role in the control of malignant melanoma. In this context, expression of MHC I, MHC II and B7 molecules by melanoma cells is seen as relevant for the immune response against the tumour. For a better understanding of the biological relevance of MHC II and B7 expression by tumour cells in metastatic melanoma, we studied the expression of these molecules in melanoma metastases in relation to the inflammatory response, regression of the tumour and survival from 27 patients treated with biochemotherapy (30 mg m−2 Cisplatin and 250 mg m−2 decarbazine (dimethyl-triazene-imidazole-carboxamide, DTIC) on days 1–3 i.v., and 107 IU IFN-α2b 3 days a week s.c., q. 28d). In 19 out of 27 lesions studied, we found expression of MHC II by the tumour cells, while only in one out of 11 tumour biopsies obtained from untreated metastatic melanoma patients, MHC II expression was detected. Expression of B7.1 and B7.2 by tumour cells was found in nine out of 24 and 19 out of 24 lesions, respectively. In all cases where B7.1 expression was found, expression of B7.2 by the tumour cells was also seen. In general, no or only few inflammatory cells positive for B7 were found. Expression of MHC II by tumour cells was positively correlated with the presence of tumour-infiltrating lymphocytes, regression of the lesion, and with time to progression (TTP) and overall survival (OS) of the patient. However, no significant correlation between B7.1 or B7.2 expression and regression of the tumour, TTP or OS was found. In light of other recent findings, these data altogether do support a role as biomarker for MHC II expression by tumour cells; however, its exact immunological pathomechanism(s) remain to be established

Decentralized diagnosis in a spacecraft attitude determination and control system

International audienceIn model-based diagnosis (MBD), structural models can provide useful information for fault diagnosis and fault-tolerant control design. In particular, they are known for supporting the design of analytical redundancy relations (ARRs) which are widely used to generate residuals for diagnosis. On the other hand, systems are increasingly complex whereby it is necessary to develop decentralized architectures to perform the diagnosis task. Decentralized diagnosis is of interest for on-board systems as a way to reduce computational costs or for large geographically distributed systems that require to minimizing data transfer. Decentralized solutions allow proper separation of industrial knowledge, provided that inputs and outputs are clearly defined. This paper builds on the results of [1] and proposes an optimized approach for decentralized fault-focused residual generation. It also introduce the concept of Fault-Driven Minimal Structurally-Overdetermined set (FMSO) ensuring minimal redundancy. The method decreases communication cost involved in decentralization with respect to the algorithm proposed in [1] while still maintaining the same isolation properties as the centralized approach as well as the isolation on request capability. 1. Introduction With increasing complexity of industrial processes, the requirement for reliability, availability and security is growing significantly. Fault detection and isolation (FDI) are becoming a major issue in industry. The structural approach constitutes a general framework to provide information when the system becomes complex. The main aim of the structural approach application is to identify the subsets of equations which include redundancy. The system structure analysis, originally developed for the decomposition of large systems of equations for their hierarchical resolution, was adopted by the Fault Detection and Isolation (FDI) community [2, 3]. Structural concepts are used for analysis of system monitor ability using the concept of complete matching on a graph. Decentralized diagnosis has received considerable attention to deal with distributed systems or with systems that may be too large to be diagnosed by one centralized site. In the same way, the decentralized solution allows proper separation of industrial knowledge, provided that inputs and outputs are clearly defined

BRIDGE: Matching Model Based Diagnosis from FDI and DX perspectives

International audienceAfter the introduction section of Chapter 7, section 7.2 first presents a brief overview of the approaches proposed by the FDI and DX model- based diagnosis communities. Although quite commonplace, this overview is neces- sary because it provides the basic concepts and principles that form the foundations of our comparative analysis. It is followed by the comparison of the mathematical objects used as input of the diagnosis procedures. Section 7.3 then establishes the correspondances of concepts on both sides and compares the techniques used by the two communities. Interestingly, the results obtained by the two approaches are shown to be the same under some assumptions that are exhibited. Finally, Section 7.4 illustrates the DX-FDI MBD bridge with the classical example of the polybox

Fault Diagnosis Of A Water For Injection System Using Enhanced Structural Isolation

A water for injection system supplies chilled sterile water as a solvent for pharmaceutical products. There are ultimate requirements for the quality of the sterile water, and the consequence of a fault in temperature or in flow control within the process may cause a loss of one or more batches of the production. Early diagnosis of faults is hence of considerable interest for this process. This study investigates the properties of multiple matchings with respect to isolability, and it suggests to explore the topologies of multiple use-modes for the process and to employ active techniques for fault isolation to enhance structural isolability of faults. The suggested methods are validated on a high-fidelity simulation of the process