Optical Smartprobes to diagnose pulmonary bacterial infections and lung cancer
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Date
02/07/2016Author
Akram, Ahsan-Ul-Haq Ramzan Khushi
Metadata
Abstract
The work in this thesis describes the approaches taken to advance the field of
pulmonary optical molecular imaging for the diagnosis of unexplained pulmonary
opacities in the critically ill patient where bacterial causes are suspected and the
investigation of pulmonary nodules and masses where lung cancer is suspected.
The bacterial work includes the development and assessment of a multivalent
fluorescently labelled antimicrobial peptide fragment that allows for the in vivo in situ
detection of bacteria in the distal lung. This Smartprobe (chapter 3), called NBD-UBIdend
remains specific for bacteria and pathogenic pulmonary fungi (Aspergillus
fumigatus) over mammalian cells, and has a clinically relevant limit of detection when
it is imaged in an ex vivo whole lung ovine ventilated model using fibered confocal
fluorescence microscopy (FCFM). Furthermore, NBD-UBIdend detects all bacteria
assessed, including a panel that accounts for 70% of ventilator associated pneumonia
causing organisms. Chapter 4, develops this further and describes the in vitro and ex
vivo evaluation of another Smartprobe utilising a fluorescently labelled modified
polymyxin B moiety, called NBD-PMX. This compound detects gram-negative but
not gram-positive bacteria and is compatible with pulmonary FCFM. This combination
of Smartprobes and FCFM could allow the immediate stratification of patient therapy
in the assessment of pulmonary opacities where bacterial causes are suspected.
The lung cancer work includes the use of label free FCFM in a clinical cohort to
determine if autofluorescence patterns can differentiate benign and malignant
pulmonary nodules. This work (chapter 5) demonstrates here there is no differentiation
using FCFM alone and therefore, for this technology to be used in lung cancer
diagnostics a Smartprobe strategy may be beneficial. Finally, chapter 6 demonstrates
a Smartprobe based approach for interrogating lung cancer and discusses a matrix
metalloproteinase (MMP) compound that detects MMPs in a whole ventilated lung
utilising a modified spontaneous ovine pulmonary adenocarcinoma model.