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Articles by M Johnson
Total Records ( 4 ) for M Johnson
  M Johnson and R. Stohr

We prove that the free centre-by-(nilpotent-of-class-(c – 1))-by-abelian groups F/[c(F'), F] are torsion-free for c = 6. This is in startling contrast to the cases when c is a prime and when c = 4, where these relatively free groups contain non-trivial elements of finite order.

  J. G Webb , D. A Wood , J Ye , R Gurvitch , J. B Masson , J Rodes Cabau , M Osten , E Horlick , O Wendler , E Dumont , R. G Carere , N Wijesinghe , F Nietlispach , M Johnson , C. R Thompson , R Moss , J Leipsic , B Munt , S. V Lichtenstein and A. Cheung

Background— The majority of prosthetic heart valves currently implanted are tissue valves that can be expected to degenerate with time and eventually fail. Repeat cardiac surgery to replace these valves is associated with significant morbidity and mortality. Transcatheter heart valve implantation within a failed bioprosthesis, a "valve-in-valve" procedure, may offer a less invasive alternative.

Methods and Results— Valve-in-valve implantations were performed in 24 high-risk patients. Failed valves were aortic (n=10), mitral (n=7), pulmonary (n=6), or tricuspid (n=1) bioprostheses. Implantation was successful with immediate restoration of satisfactory valve function in all but 1 patient. No patient had more than mild regurgitation after implantation. No patients died during the procedure. Thirty-day mortality was 4.2%. Mortality was related primarily to learning-curve issues early in this high-risk experience. At baseline, 88% of patients were in New York Heart Association functional class III or IV; at the last follow-up, 88% of patients were in class I or II. At a median follow-up of 135 days (interquartile range, 46 to 254 days) and a maximum follow-up of 1045 days, 91.7% of patients remained alive with satisfactory valve function.

Conclusions— Transcatheter valve-in-valve implantation is a reproducible option for the management of bioprosthetic valve failure. Aortic, pulmonary, mitral, and tricuspid tissue valves were amenable to this approach. This finding may have important implications with regard to valve replacement in high-risk patients.

  I Zegers , T Keller , W Schreiber , J Sheldon , R Albertini , S Blirup Jensen , M Johnson , S Trapmann , H Emons , G Merlini and H. Schimmel

The availability of a suitable matrix reference material is essential for standardization of the immunoassays used to measure serum proteins. The earlier serum protein reference material ERM-DA470 (previously called CRM470), certified in 1993, has led to a high degree of harmonization of the measurement results. A new serum protein material has now been prepared and its suitability in term of homogeneity and stability has been verified; after characterization, the material has been certified as ERM-DA470k/IFCC.


We characterized the candidate reference material for 14 proteins by applying a protocol that is considered to be a reference measurement procedure, by use of optimized immunoassays. ERM-DA470 was used as a calibrant.


For 12 proteins [2 macroglobulin (A2M), 1 acid glycoprotein (orosomucoid, AAG), 1 antitrypsin (1-protease inhibitor, AAT), albumin (ALB), complement 3c (C3c), complement 4 (C4), haptoglobin (HPT), IgA, IgG, IgM, transferrin (TRF), and transthyretin (TTR)], the results allowed assignment of certified values in ERM-DA470k/IFCC. For CRP, we observed a bias between the lyophilized and liquid frozen materials, and for CER, the distribution of values was too broad. Therefore, these 2 proteins were not certified in the ERM-DA470k/IFCC. Different value transfer procedures were tested (open and closed procedures) and found to provide equivalent results.


A new serum protein reference material has been produced, and values have been successfully assigned for 12 proteins.

  A. J Rodger , N Brecker , S Bhagani , T Fernandez , M Johnson , A Tookman and A. Bartley

Background Unemployment in the human immunodeficiency virus (HIV) population remains a major issue. Recent changes in the benefits system have triggered concerns about (re)integration into work for adults with HIV.

Aims To examine attitudes and barriers to employment in HIV patients.

Methods We undertook a cross-sectional study in the Royal Free HIV outpatient department from December 2008 to February 2009. The questionnaire collected data on demographics, date of HIV diagnosis, combination antiretroviral therapy, CD4 count, employment status, attitudes to work, psychological health and perception of barriers to employment. Logistic regression analyses were used to assess factors associated with not working.

Results Five hundred and forty-five HIV patients took part. Overall, 26% were not working and of these, half (53%) had been unemployed for >5 years. Associations with not working were having been diagnosed with HIV >10 years before, poor psychological health and poor attitudes to employment. There was no association between objective measures of health (CD4 count) and employment status. Those not working were less likely to agree with that ‘work is good for physical and mental health’ (90 versus 97%: P < 0.01) and more likely to agree that ‘should only work if 100% fit and well’ (76 versus 51%: P < 0.001) compared to workers. Those currently not working had negative perceptions of their abilities to gain employment and to remain in work.

Conclusions There are opportunities for HIV services to provide psychological support around attitudes associated with unemployment and to help HIV-positive men in particular obtain and remain in work.

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