Biomedical subjects
Publications and source records attributed to J Beynon.
A nonopaque methyl methacrylate mass that had the appearance of an abscess in a postoperative CT scan of the spine is described. Contained gas produced an attentuation range of +20 to -300 HU, with an average of -80 to -250 HU. This finding was confirmed by CT examination of a separate cement mass removed from a similar patient.
Low back pain is a very common clinical problem, the cause of which is frequently poorly understood. Improvements in equipment design and scanning techniques have resulted in a better anatomical display of the lumbar spine by computed tomographic (CT) scanning. Advances in this area have provided a considerable insight into the causes of the lumbago-sciatica syndrome.
We have determined the precise point of transcription initiation for five nif (nitrogen fixation) operons of Klebsiella pneumoniae and sequenced the promoters. Our results show that nifF is transcribed in the opposite direction to that previously proposed for nif genes, that nifM is transcribed from two promoters, and that there is a promoter preceding nifU but not nifX, and we present a revised map of nif transcripts. The nif promoters have a characteristic structure of 26 bp located between positions--1 and --26 upstream of the site of transcription initiation: CTGG..8bp...TTGCA...9bp...Py(+1). This structure, which has two regions of conserved sequence, shows no homology to the "consensus promoter" of enteric bacteria. Our results suggest that the--10 homology is equivalent to a "Pribnow box" for promoters expressed under nitrogen-starved conditions and that the--23 homology confers activator specificity on the nif promoters.
A new automated suction device has been developed to aspirate the contents of the distal oesophagus to monitor the constituents of the refluxate in patients with gastro-oesophageal reflux disease. Using antimony and glass electrodes with solid-state pH recorders it has been conclusively shown that gastric acid is responsible for the mucosal damage seen in reflux oesophagitis but new evidence is emerging that other constituents of the gastroduodenal juice, in particular bile acids, are also damaging to the oesophageal mucosa. The main difficulty lies in that there is no reliable method of monitoring this component of the refluxate except by direct aspiration of the contents for assay. This new technique of oesophageal sampling utilizing a software-controlled suction process with simultaneous pH recording has helped to identify patients at risk of refluxing potentially harmful substances and is a valuable addition to the armamentarium of investigative procedures for patients with gastro-oesophageal reflux disease.
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