A method for rapid quantitative assessment of biofilms with biomolecular staining and image analysis

The accumulation of bacteria in surface-attached biofilms can be detrimental to human health, dental hygiene, and many industrial processes. Natural biofilms are soft and often transparent, and they have heterogeneous biological composition and structure over micro- and macroscales. As a result, it is challenging to quantify the spatial distribution and overall intensity of biofilms. In this work, a new method was developed to enhance the visibility and quantification of bacterial biofilms. First, broad-spectrum biomolecular staining was used to enhance the visibility of the cells, nucleic acids, and proteins that make up biofilms. Then, an image analysis algorithm was developed to objectively and quantitatively measure biofilm accumulation from digital photographs and results were compared to independent measurements of cell density. This new method was used to quantify the growth intensity of Pseudomonas putida biofilms as they grew over time. This method is simple and fast, and can quantify biofilm growth over a large area with approximately the same precision as the more laborious cell counting method. Stained and processed images facilitate assessment of spatial heterogeneity of a biofilm across a surface. This new approach to biofilm analysis could be applied in studies of natural, industrial, and environmental biofilms.

Graphical abstract

Optical protein modulation via quantum dot coupling and use of a hybrid sensor protein

Harnessing the energy transfer interactions between the optical protein bacteriorhodopsin (bR) and CdSe/ZnS quantum dots (QDs) could provide a novel bio-nano electronics substrate with a variety of applications. In the present study, a polydimethyldiallyammonium chloride based I-SAM technique has been utilized to produce bilayers, trilayers and multilayers of alternating monolayers of bR, PDAC and QD's on a conductive ITO substrate. The construction of multilayer systems was directly monitored by measuring the unique A570 nm absorbance of bR, as well as QD fluorescence emission. Both of these parameters displayed a linear relationship to the number of monolayers present on the ITO substrate. The photovoltaic response of bilayers of bR/PDAC was observed over a range of 3 to 12 bilayers and the ability to efficiently create an electrically active multilayered substrate composed of bR and QDs has been demonstrated for the first time. Evaluation of QD fluorescence emission in the multilayer system strongly suggests that FRET coupling is occurring and, since the I-SAM technique provide a means to control the bR/QD separation distance on the nanometer scale, this technique may prove highly valuable for optimizing the distance dependent energy transfer effects for maximum sensitivity to target molecule binding by a biosensor. Finally, preliminary studies on the production of a sensor protein/bR hybrid gene construct are presented. It is proposed that the energy associated with target molecule binding to a hybrid sensor protein would provide a means to directly modulate the electrical output from a sensor protein/bR biosensor platform.

The role of education in developing specialist practice

It really is a great pleasure for me to write this paper. Before EDTNA was born, when it was a only a glimmer in its Mother's eye, I fell in love with renal nursing. And it was through renal nursing that I became involved with the Royal College of Nursing of the United Kingdom, which has played such an important role in advancing the art and science of nursing, and in encouraging the development of clinical nursing expertise, and the role of specialist practice.

10 years' experience with regular haemodialysis and renal transplantation

75 children aged under 15 years have entered the regular haemodialysis/renal transplant programme at Guy's Hospital in the 10 years since its inception; 13 children have subsequently died. A combination of hospital and home haemodialysis and renal transplantation was used. 64 children received 80 renal allografts; 37 1st grafts were from live, related donors and 27 were from cadaver donors. The 5-year acturial patient survival for the whole group and for those who had transplants was 76%. Live donor graft survival was 65% at 3 years, and 55% at 5 years; 1st cadaver graft survival was 42% at 3 years. Results obtained during the last 6 years of the 10-year period showed an improvement with a live related donor graft survival rate of 71%, and a 1st cadaver graft survival rate of 47% at 3 years. Particular experience was gained with home haemodialysis and live, related donor transplantation. Despite growth, and psychosocial and rehabilitation problems, the overall results were encouraging, particularly for the 46 children who had successful transplants. These children grew better, had fewer psychosocial difficulties, and were rehabilitated more successfully into normal life than those on long-term dialysis. We conclude that dialysis and transplantation should be offered to all suitable children with terminal renal failure.

Presentation, management, complications, and outcome of acute renal failure in childhood: five years' experience

During 1971-5, 72 episodes of acute renal failure were treated in 70 children aged up to 16 years. The commonest causes were renal hypoperfusion (31 cases), haemolytic-uraemic syndrome (12), glomerulonephritis (9), septicaemia (5), and congenital abnormalities (6). Though referral from other hospitals was generally prompt, 10 out of 51 patients had been observed for up to seven days before transfer. Dailysis was used in 44 cases, the most common complications of which were peritonitis in those treated with peritoneal dialysis and acute changes in fluid balance in those treated with haemodialysis. Altogether 37 patients fully recovered, 10 were discharged with chronically impaired renal function, 17 died, and six entered the dialysis and transplantation programme. The mortality fell from 33% in 1972 to 20% in later years, which was due solely to maintenance dialysis being available. Though all patients with irrevocable kidney failure who were suitable entered the dialysis and transplantation programme, with current financial restrictions we doubt whether we shall be able to find places for all such patients in the future.