Anti-epidermal growth factor receptor monoclonal antibodies affecting signal transduction

Monoclonal antibodies prepared against tyrosine phosphorylated epidermal growth factor receptor (EGFR) were tested for their effects on transmembrane signal transduction in A431 tumor cells. Monoclonal antibodies (mab) defined by SDS-sensitive epitopes, i.e., epitopes with conformational specificity, were most effective. Mab 5-125 reacting with a site of the extracellular EGFR domain blocked EGF-binding and cell proliferation in vitro, as well as tumor growth in vivo. However, this mab appeared not to be internalized upon binding to EGFR and did not trigger EGFR autophosphorylation. In contrast, mab 5-D43, also defined by an SDS-sensitive epitope and reacting with an extracellular EGFR site, did not block EGF binding but was readily internalized after binding to EGFR of untreated A431 cells. This mab induced EGFR tyrosine phosphorylation in cell lysates and tyrosine-specific autophosphorylation of insolubilized EGFR immune complexes. Cell growth in vitro was greatly stimulated in the presence of mab 5-D43. Since interaction of mab 5-D43 with EGFR induced most EGF-specific functions, although it did not bind to the EGF-specific site of EGFR, we have to assume that binding of mab 5-D43 to EGFR induced a conformational shift that activated the cytoplasmic EGFR kinase site. On the other hand, activation and/or accessibility of the EGFR kinase site could be blocked by mab 1-594, which is defined by an SDS-insensitive protein epitope of the cytoplasmic EGFR domain. Blocking of the EGFR kinase site by mab 1-594 also abolished EGF-induced tyrosine phosphorylation of endogenous cellular substrates with molecular masses of 145, 97, 85, 37, and 32 kDa, as well as of exogenous substrates such as GAT copolymer

Ubiquitin-conjugating enzymes: novel regulators of eukaryotic cells

Covalent attachment of ubiquitin to cellular proteins is essential for cell viability and is catalysed by a set of distinct ubiquitin-conjugating enzymes. Individual members of this novel enzyme family mediate strikingly diverse functions, including DNA repair, cell cycle control, selective protein degradation and essential functions of the stress response

Resistance to cadmium mediated by ubiquitin-dependent proteolysis

Cadmium is a potent poison for living cells. In man, chronic exposure to low levels of cadmium results in damage to kidneys and has been linked to neoplastic disease and ageing, and acute exposure can cause damage to a variety of organs and tissues. Cadmium reacts with thiol groups and can substitute for zinc in certain proteins, but the reason for its toxicity in vivo remains uncertain. In eukaryotes, an important selective proteolysis pathway for the elimination of abnormal proteins that are generated under normal or stress conditions is ATP-dependent and mediated by the ubiquitin system. Substrates of this pathway are first recognized by ubiquitin-conjugating enzymes (or auxiliary factors) which covalently attach ubiquitin, a small and highly conserved protein, to specific internal lysine residues of proteolytic substrates. Ubiquitinated substrates are then degraded by the proteasome, a multisubunit protease complex. Here we show that expression of this ubiquitin-dependent proteolysis pathway in yeast is activated in response to cadmium exposure and that mutants deficient in specific ubiquitin-conjugating enzymes are hypersensitive to cadmium. Moreover, mutants in the proteasome are hypersensitive to cadmium, suggesting that cadmium resistance is mediated in part by degradation of abnormal proteins. This indicates that a major reason for cadmium toxicity may be cadmium-induced formation of abnormal proteins

Alternative access to product information on consumer packages in supermarkets and in smart home environments

Many consumers, especially elderly, blind or visually impaired people, have problems in accessing product label information on foodstuffs and household detergents. The idea for the "universal access to product label information" is based on the identification of a product via its bar-code (EAN), an automatically generated query to a product database and a customised presentation of product information. These functions are provided by an info-device called 'TeleEye'. It enables even blind users to distinguish products at home and supports visually impaired people at shopping in supermarkets. Since it is able to check product descriptions for user-individual ingredients (for diet or allergy) and to produce corresponding warnings, especially elderly people with special dietary needs benefit from the system. The Internet-based European consumer product database system, the management of ingredient and diet specific expert knowledge, and the users' info-device are realised in private and public applications within the European IST-project PACKAGE

Internet-based treatment of major depression for patients on a waiting list for inpatient psychotherapy: protocol for a multi-centre randomised controlled trial

Background: Major depressive disorder (MDD) is a prevalent and severe disorder. Although effective treatments for MDD are available, many patients remain untreated, mainly because of insufficient treatment capacities in the health care system. Resulting waiting periods are often associated with prolonged suffering and impairment as well as a higher risk of chronification. Web-based interventions may help to alleviate these problems. Numerous studies provided evidence for the efficacy of web-based interventions for depression. The aim of this study is to evaluate a new web-based guided self-help intervention (GET.ON-Mood Enhancer-WL) specifically developed for patients waiting to commence inpatient therapy for MDD.Methods: In a two-armed randomised controlled trial (n = 200), the web-based guided intervention GET.ON-Mood Enhancer-WL in addition to treatment as usual (TAU) will be compared with TAU alone. The intervention contains six modules (psycho education, behavioural activation I & II, problem solving I & II, and preparation for subsequent inpatient depression therapy). The participants will be supported by an e-coach, who will provide written feedback after each module. Inclusion criteria include a diagnosis of MDD assessed with a structured clinical interview [SCID] and a waiting period of at least three weeks before start of inpatient treatment. The primary outcome is observer-rated depressive symptom severity (HRS