Mucins in normal and diseased airways

Mucus glycoproteins (mucins) are the principal constituents of respiratory secretions in health and disease. The increased 'acidity' of mucin producing cells in the bronchitic airways is not reflected in a change of negative charge of bronchitic mucins. Furthermore, the size and macromolecular properties of mucins from chronic bronchitic sputa do not differ significantly from those in normal airways. Antibodies against a peptide within the MUC5AC mucin recognize a distinct mucin population in airway mucus. This mucin is large and oligomeric and immunohistochemistry revealed it to be of goblet cell origin. In addition, another population of large oligomeric mucins was identified in the submucosa, probably originating from the submucosal glands. The MUC2 mucin was shown not to be a prominent mucin in airway secretions. Bovine trachea was established as a model to study mucin biosynthesis and secretion. The uptake of radioactive glycoprotein precursors by mucin producing cells was monitored by autoradiography and 35S-sulphate, in particular, was incorporated into secreted as well as intracellular mucins. Radiolabelled mucins, secreted into the medium, were smaller and had a higher byoyant density than the predominant species identified in tracheal lavage. The trachea in organ culture may thus not correspond to those secreted by the intact tissue. This observation may have important consequences for the interpretation of data on the synthesis and secretion of mucus-glycoproteins in vitro

Portfolio as a method for continuous assessment in an undergraduate health education programme.

A portfolio assessment system has been introduced into a biomedical science programme to promote both continuous learning and deep approaches to learning. Attention has been focused on creating harmony between the assessment system and the PBL curriculum of the programme. Biomedicine and laboratory work are central in the curriculum. The portfolio included evidence of laboratory work, personal reflections and certificates from the PBL tutor. The portfolio was assessed on three occasions over 20 weeks. The grades were 'pass' or 'fail'. The tutor certificate appeared to be a crucial part of the portfolio since a 'fail' in this part usually led to an overall 'fail'. Both students and teachers were concerned about ensuring that enough factual knowledge, as measured by a traditional test, had been achieved. The agreement was good enough for the pass or fail level but some expected differences were found at the detailed level. The course, including the portfolio, was evaluated orally during weekly whole-group meetings and using a questionnaire at the end. The students felt comfortable with the portfolio system and preferred it to a traditional test. The teachers felt that they needed to develop their teacher-student discussion skills and to improve their feedback on the reflections. Peer assessment between students is proposed as a line of action to enhance the credibility of the crucial tutor certificate. The portfolio might be an efficient tool for the students to concentrate their efforts on the most central concepts of medical laboratory work. The model will be developed through further discussions and better consensus among faculty