Cellular immune responses to recurring influenza strains have limited boosting ability and limited cross-reactivity to other strains.

Influenza vaccine provides protection against infection with matched strains, and this protection correlates with serum antibody titres. In addition to antibodies, influenza-specific CD8+ T-lymphocyte responses are important in decreasing disease severity and facilitating viral clearance. Because this response is directed at internal, relatively conserved antigens, it affords some cross-protection within a given subtype of influenza virus. With the possibility of a broader A(H1N1) Mexico outbreak in the fall of 2009, it appeared worthwhile studying the degree of cellular immune response-mediated cross-reactivity among influenza virus isolates. The composition of the 2006-2007 influenza vaccine included the A/New Caledonia/20/1999 strain (comprising a virus that has been circulating, and was included in vaccine preparations, for 6-7 years) and two strains not previously included (Wisconsin and Malaysia). This combination afforded us the opportunity to determine the degree of cross-reactive cellular immunity after exposure to new viral strains. We analysed the antibody responses and the phenotype and function of the T cell response to vaccine components. The results obtained show that antibody responses to A/New-Caledonia were already high and vaccination did not increase antibody or cytotoxic T lymphocyte responses. These data suggest that repeated exposure to the same influenza stain results in limited boosting of humoral and cellular immune responses.

Accuracy of the Dinamap 1846 XT automated blood pressure monitor.

Accurate blood pressure (BP) measurement is important for the detection and treatment of hypertension. Despite widespread use of automated devices, there is limited published evidence for their reliability and accuracy. To determine the reliability and accuracy of the Dinamap 1846XT (Critikon Corporation, Tampa, FL, USA), a commonly used non-invasive oscillometric BP monitor The Dinamap was evaluated against the mercury manometer in 70 randomly selected adult hospitalised medical patients. Each individual underwent three sets of standardised BP measurement by automated method and three sets by mercury manometer by two independent observers. Reliability of BP measurement was assessed by repeated measures analysis. Dinamap accuracy was evaluated according to the American Association of Medical Instrumentation (AAMI) and British Hypertension Society (BHS) guidelines. Most patients were either normotensive or had stage I hypertension. The Dinamap tended to overestimate lower diastolic BP, and displayed poor reliability (P < 0.05). despite meeting aami guidelines, only 59% of systolic and 56% of diastolic dinamap readings were within 5 mm hg of the mercury manometer and 84% of systolic and 80% of diastolic readings were within 10 mm hg (bhs grade c). systolic and diastolic accuracy were worse with pressures >160/90 mm Hg (grade D) although these measures were based on a smaller sample of subjects. In conclusion the Dinamap yields inaccurate estimates of both systolic and diastolic BP even under standardised, and thus optimal conditions. This inaccuracy is exaggerated at higher BP (>160/90 mm Hg), although the number of measurements at higher pressures was small. We recommend that this device not be used when accurate BP measurement is needed for therapeutic decision-making.

Characterisation of fibrillin-1 cDNA clones in a human fibroblast cell line that assembles microfibrils.

Fibrillin-1 is a large extracellular glycoprotein which is a major structural component of 10-12 nm microfibrils. Defects in human fibrillin-1 give rise to the autosomal dominant connective tissue disease the Marfan syndrome and related disorders. Previous studies examining the biosynthesis and secretion of recombinant fibrillin-1 fragments have been performed in cell lines which do not assemble fibrillin into extracellular 10-12 nm microfibrils. Conflicting data have been obtained regarding N-terminal processing. In this study we have characterised a human fibroblast cell line MSU-1.1 which shows a similar endogenous fibrillin-1 pulse chase profile to primary human dermal fibroblasts and produces microfibrils. Expression of a approximately 50 kDa N-terminal recombinant peptide in MSU-1.1 resulted in efficient secretion of this peptide into conditioned media, N-terminal sequence analysis of the purified peptide identified 2 protease cleavage sites and a presumed signal peptidase site. Together these data identify the natural leader sequence of fibrillin-1 and the presence of two processing sites in the N-terminus of fibrillin-1. The identification of an N-terminal processing site in recombinant fibrillin-1 similar to that obtained in a previous study which used an HT1080 fibrosarcoma host cell line excludes defective N-terminal processing as the cause of the assembly defect in this cell line. A full length normal and mutant fibrillin cDNA (approximately 8.6 kb) was constructed and stable integration of each into MSU1.1 led to RNA transcription at approximately 5% of endogenous levels. This is the first report of transcription from the full length fibrillin-1 cDNA. The low levels of transcription achieved, suggest that additional upstream and downstream DNA sequence elements will be required for high levels of full length fibrillin-1 cDNA expression.