The tracheal system of the Common Wasp (Vespula vulgaris) - A micro-CT study.

X-ray micro-CT has been used to study the tracheal system of Pre and Post hibernation Queen wasps (Vespula vulgaris) and their workers. We have compared our findings in wasps with Snodgrass's description of the tracheal system of the honeybee as characterised by anatomical dissection. Our images, whilst broadly similar, identify the tracheal system as being considerably more complex than previously suggested. One of the 30 wasps imaged had a markedly different, previously undescribed tracheal system. Since completing this study, a large micro-CT study from the American Museum of Natural History (AMNH) has been published. This used different software (Slicer) and analysed 16bit digital data. We have compared our methods with that described in the AMNH publication, adopted their suggested nomenclature and have made recommendations for future studies.

Visualising fat reserves in an insect: A method using X-ray micro-computerised tomography of the Common Wasp (Vespula vulgaris).

The Common Wasp, Vespula vulgaris (Hymenoptera: Vespidae), has an annual nest cycle with new colonies initiated by over-wintered queens. Survival of adult queen wasps through winter dormancy is enabled through the deposition of substantial quantities of triglycerides in fat bodies. Worker (and male) wasps lack these fat reserves. By comparing micro-CT scans of workers, pre-hibernation queens and post-hibernation queens, we demonstrate that it is possible to semi-quantitatively measure fat reserves using arbitrary X-ray attenuation ranges. Venom in the venom gland of the queen wasps, has a significantly lower X-ray attenuation value than the triglyceride-rich fat bodies. This may be due to its content of low molecular weight volatile pheromones in addition to its other known constituents. We also demonstrate the utility of micro-CT for visualising a range of physiological and anatomical features of insects. This non-destructive method for measuring fat reserves can be used on appropriately preserved or freshly collected insect specimens.

Three-dimensional rendering of otolith growth using phase contrast synchrotron tomography.

A three-dimensional computer reconstruction of a plaice Pleuronectes platessa otolith is presented from data acquired by the Diamond Light synchrotron, beamline I12, X-ray source, a high energy (53-150 keV) source particularly well suited to the study of dense objects. The data allowed non-destructive rendering of otolith structure, and for the first time allows otolith annuli (internal ring structures) to be analysed in X-ray tomographic images.

Long-term study of re-infection following successful eradication of Helicobacter pylori infection.

BACKGROUND: 'Re-infection' with Helicobacter pylori after eradication has been estimated to occur in 0-14% of patients, although most so-called 're-infections' occur within the first year following 'eradication' and many may actually be due to recrudescence of a temporarily suppressed infection. AIM: To study the true re-infection rate, we have studied re-infection rates after eradication therapy by excluding the first year's data, minimizing the possible confounding effect of recrudescence. METHODS: All patients tested for H. pylori infection following eradication therapy between 1987 and 2004 were evaluated. Testing was carried out by urea breath test and gastric biopsy. Patients were included if they were found to be negative for H. pylori infection by testing at least 1 year following eradication and underwent at least one further test for H. pylori. RESULTS: 1162 patients met the inclusion criteria with median post-eradication follow-up of 3 years (1.5-14) including 4668 tests; 3319 years of follow-up were analysed. Thirteen cases of re-infection occurred (re-infection rate 0.4% per year). CONCLUSIONS: This large study of H. pylori re-infection avoided cases of recrudescence by excluding the first post-eradication year. True re-infection is probably less common than previously thought.

Recording forces exerted on the bowel wall during colonoscopy: in vitro evaluation.

A novel system for distributed force measurement between the bowel wall and the shaft of a colonoscope is presented. The system, based on the piezoresistive method, involves the integration of soft miniature transducers to a colonoscope to enable a wide range of forces to be sensed. The attached sensing sheath does not restrict the propulsion of the colonoscope nor notably alter its flexibility. The addition of the sensor sheath increases the colonoscope diameter by 15-20% depending on the type of the colonoscope (adult or paediatric). The transducer's accuracy is +/-20 grammes if it is not subjected to extensive static forces. Under large static force conditions the errors may increase to +/-50 grammes. The tactile force measuring sensors have provided preliminary results from experiments on a model of the large bowel. The force measurements confirm the predictions on the location and magnitude of the forces and that most of the forces are exerted whilst the instrument is looping.

Preparation, premedication, and surveillance.

The main criteria for assessing conscious sedation (perhaps now more correctly termed "moderate sedation/analgesia") continue to be patient satisfaction and comfort, short duration, amnesia, and above all, patient safety. The problems reviewed last year - including the increasing pressure on endoscopy units to perform yet more procedures, reduce costs, and achieve shorter patient turn-around times - certainly have not gone away. Studies reviewed this year suggest that although many endoscopic procedures, such as oesophagogastroduodenoscopy (OGD), colonoscopy, and endoscopic ultrasonography (EUS) can indeed be performed without intravenous sedation, many patients still prefer to be sedated. Further papers on the possible role of ultrathin endoscopes in unsedated OGD are reviewed here. A study in Italy comparing virtual computed-tomographic (CT) colonography and conventional colonoscopy suggests that unsedated colonoscopy is unlikely to meet with wide acceptance. Audits of colonoscopy in both the United States and the United Kingdom suggest that there is still a long way to go before caecal intubation rates of more than 90 % are regularly attained. The evidence suggests that some endoscopists are using larger doses of a midazolam and pethidine combination than are generally recommended (particularly in elderly patients), and sedation-related deaths are still occurring. Impressively large clinical studies, particularly those from Switzerland, on the use of propofol administered by nonanaesthetists are leading to reconsideration of the earlier view that propofol should only be used by anaesthetists. If propofol is to be used more widely and become an agent administered by endoscopists (or nursing staff), then considerable improvements in the standard of airways management will be needed. Several new studies relating to bowel-cleansing agents and the use of a carbohydrate/electrolyte "cholera mixture" to prevent the associated intravascular volume contraction have been published. Warm water is a cheap and effective way of reducing colonic spasm during colonoscopy, and intraluminal peppermint oil is a good antispasmodic in the stomach as well as the colon. Sedation should still be regarded as one part of an overall "endoscopy package". Finally, more attention needs to be given to patients' complaints regarding what are often considered by endoscopists to be "trivial complications" if the patients are to have a positive experience of their examination that will lead to them being prepared to come back a second time.

Premedication, preparation, and surveillance.

The vigorous debate over whom to sedate, when to sedate, and how to sedate shows no sign of running out of steam. There is a general consensus that patients should be more involved in the decision-making process for the sedation "menu". A move away from the take-it-or-leave-it attitude of all or nothing to an "à la carte" choice is to be encouraged. A new textbook and several further guidelines have appeared. The particular problems associated with sedating the elderly are briefly presented. The pros and cons of using local pharyngeal anaesthesia are discussed. Enthusiasm for the use of intravenous propofol is gathering momentum, despite continuing worries about its safety in the hands of the nonanaesthetist. For many endoscopists, the combination of a benzodiazepine plus (or minus) an opioid with which they are most familiar is still the best compromise in terms of efficacy, cost, and safety. Fatal drug-induced cardiopulmonary complications continue to occur, despite a general trend toward using smaller doses of sedation than we did 5 - 10 years ago. Monitoring techniques that are at present considered as research tools may one day become commonplace. These include: the use of an electroencephalography parameter known as bispectral analysis; transcutaneous CO(2) measurement; and a modified continuous capnographic waveform trace to monitor ventilatory effort. Bispectral analysis may be of use in monitoring central nervous system depression and helping to distinguish between conscious sedation and deep sedation. If the measurement of CO(2) levels, either transcutaneously or in breath samples, was as easy and inexpensive as measuring SpO(2) with a pulse oximeter, then undoubtedly such technology would enhance the early detection of sedative-induced hypoventilation and apnoea. Further evidence regarding droperidol's possible role in conscious sedation is presented. Pain during colonoscopy remains a problem, and the possible role for intraluminal injection of peppermint oil, as well as the value of variable-stiffness colonoscopes, in reducing the need for intravenous sedation is discussed. Case reports of hyponatraemic encephalopathy and hypocalcaemic tetany as complications of oral bowel preparation are presented, as is the challenge associated with adequate bowel preparation in diabetic patients.

Auditory display of knee-joint vibration signals.

Sounds generated due to rubbing of knee-joint surfaces may lead to a potential tool for noninvasive assessment of articular cartilage degeneration. In the work reported in the present paper, an attempt is made to perform computer-assisted auscultation of knee joints by auditory display (AD) of vibration signals (also known as vibroarthrographic or VAG signals) emitted during active movement of the leg. Two types of AD methods are considered: audification and sonification. In audification, the VAG signals are scaled in time and frequency using a time-frequency distribution to facilitate aural analysis. In sonification, the instantaneous mean frequency and envelope of the VAG signals are derived and used to synthesize sounds that are expected to facilitate more accurate diagnosis than the original signals by improving their aural quality. Auditory classification experiments were performed by two orthopedic surgeons with 37 VAG signals including 19 normal and 18 abnormal cases. Sensitivity values (correct detection of abnormality) of 31%, 44%, and 83%, and overall classification accuracies of 53%, 40%, and 57% were obtained with the direct playback, audification, and sonification methods, respectively. The corresponding d' scores were estimated to be 1.10. -0.36, and 0.55. The high sensitivity of the sonification method indicates that the technique could lead to improved detection of knee-joint abnormalities; however, additional work is required to improve its specificity and achieve better overall performance.

The measurement of forces exerted during colonoscopy.

BACKGROUND: The widely varying forces used at colonoscopy have not been measured. An electronic device was designed to measure the forces exerted by the clinician on the endoscope during colonoscopy. METHODS: The device featured a handle designed in the shape of a hinged split cylinder that could be locked around the endoscope but readily moved up and down the insertion tube as the colonoscopy proceeded. This cylinder contained strain-gauges arranged so that the forces transmitted could be accurately measured. The device recorded the torque forces in addition to the push and pull forces exerted during diagnostic colonoscopy. RESULTS: In a series of 21 colonoscopies in 20 patients: peak pushing force = 4.4 kg, pulling force = -1.8 kg, anti-clockwise torque = 1.0 Newton meters, clockwise torque = 0.8 Newton meters. Percentage time force greater than 1 kg = 5%. Peak anal insertion force = 1.8 kg. CONCLUSIONS: These measurements represent the first accurate measurements of the forces exerted during colonoscopy. Reducing the force during colonoscopy is likely to diminish pain and reduce the risk of perforation. A knowledge of these forces may also help with the design of new instruments and models for teaching or research.

Adaptive time-frequency analysis of knee joint vibroarthrographic signals for noninvasive screening of articular cartilage pathology.

Vibroarthrographic (VAG) signals emitted by human knee joints are nonstationary and multicomponent in nature; time-frequency distributions (TFD's) provide powerful means to analyze such signals. The objective of this paper is to construct adaptive TFD's of VAG signals suitable for feature extraction. An adaptive TFD was constructed by minimum cross-entropy optimization of the TFD obtained by the matching pursuit decomposition algorithm. Parameters of VAG signals such as energy, energy spread, frequency, and frequency spread were extracted from their adaptive TFD's. The parameters carry information about the combined TF dynamics of the signals. The mean and standard deviation of the parameters were computed, and each VAG signal was represented by a set of just six features. Statistical pattern classification experiments based on logistic regression analysis of the parameters showed an overall normal/abnormal screening accuracy of 68.9% with 90 VAG signals (51 normals and 39 abnormals), and a higher accuracy of 77.5% with a database of 71 signals with 51 normals and 20 abnormals of a specific type of patellofemoral disorder. The proposed method of VAG signal analysis is independent of joint angle and clinical information, and shows good potential for noninvasive diagnosis and monitoring of patellofemoral disorders such as chondromalacia patella.

Premedication, preparation, and surveillance.

Once again the staggering variation in IV sedation practice between different countries is highlighted. This year the "to sedate or not sedate" debate focuses on colonoscopy. Several papers on the use of Propofol are reviewed. It remains this authors' opinion that propofol is an anaesthetic agent to be used by (or at least in the presence of) an anaesthetist. Informed consent and the question of what to do if a patient withdraws consent halfway through the procedure are discussed. Predictably further recent papers on the relative merits of midazolam and diazepam are presented plus another report on the use of flumazenil in the recovery period. The use of 3% hydrogen peroxide solution to aid the visualization of acutely bleeding gastro-duodenal lesions is presented in two papers along with a discussion of its possible mode of action. The use of antispasmodics to aid colonoscopy is further discussed: this year concentrating on the use of hyoscyamine sulphate (as opposed to hyoscine butylbromide, the preferred agent in the UK). The patients receiving hyoscyamine sulphate had significantly shorter caecal intubation times, better sedation and easier colonic insertion. The "downside" was drug-induced tachycardia and the authors caution against the widespread use of this drug until this situation is further clarified. The subject of hypoxaemia at the time of gastroscopy, colonoscopy and ERCP was reviewed last year and further papers are presented in which the incidence of various levels of hypoxia are given. In anaesthetic circles it would be considered totally unacceptable to allow a patient's oxygen saturation to fall below 85 %, and yet we continue to have papers reporting its incidence. This level of desaturation is potential dangerous and the routine use of supplemental oxygen would greatly reduce this unneccessary risk to patients.

Depth of insertion at flexible sigmoidoscopy: implications for colorectal cancer screening and instrument design.

BACKGROUND AND STUDY AIMS: The depth of insertion at flexible sigmoidoscopy is variable, depending upon bowel preparation, patient tolerance and distal colonic anatomy. Many endoscopists routinely aim to insert the 60 cm flexible sigmoidoscope to the splenic flexure; however internal endoscopic markers are unreliable, making the true anatomical extent of the examination difficult to assess. The aim of this study was to assess the depth of insertion at flexible sigmoidoscopy. PATIENTS AND METHODS: Two separate studies were done. In the first (study 1), magnetic endoscopic imaging was used to determine the final depth of insertion at non-sedated, screening flexible sigmoidoscopy. In the second (study 2), "real-time" imaging was utilized to determine sigmoid looping and the anatomical location of the endoscope tip after 60 cm of instrument had been inserted during total or limited colonoscopy. A total of 117 consecutive average-risk patients, aged 55-65 years participated in study 1, and 136 patients underwent either limited, (33) or attempted total colonoscopy (103) in study 2. RESULTS: In study 1 the median insertion distance was 52 cm, range 20-58. In 61 % of patients the imaging system showed that the descending colon had not been visualized by the end of the procedure. Failure to reach the sigmoid/descending junction occurred in 29 (24%) patients. Reasons for failure included poor tolerance of the procedure due to pain (23 patients) inadequate preparation (3 patients) and, excessive looping (3 patients). In study 2, after 60 cm of instrument had been inserted, the splenic flexure or beyond was reached in 29% and the descending colon in 9%, whilst in 62 % the endoscope tip had not passed beyond the sigmoid/descending colon junction. A sigmoid loop formed in 70% of patients, and unusual loops such as the alpha, reverse alpha and reverse sigmoid spiral loop occurred more frequently in women compared to men (P = 0.0249). In those 104 patients where the splenic flexure was reached the mean maximum length of instrument inserted prior to reaching the flexure was 75.4 cm, (SD = 21.9). CONCLUSIONS: Examination of the entire sigmoid was not achieved in approximately one-quarter of patients undergoing screening flexible sigmoidoscopy, mainly because of discomfort. The descending colon is intubated in a minority of cases (using standard instruments), even after 60 cm has been inserted. Alternative instruments with different shaft characteristics (floppy, narrow calibre, 80-100 cm in length) may be necessary to ensure deeper routine intubation in nonsedated patients.

Colonoscopy aided by magnetic 3D imaging: assessing the routine use of a stiffening sigmoid overtube to speed up the procedure.

There are not enough trained colonoscopists to cope with the present recommended number of examinations required for diagnostic and surveillance purposes. If colorectal cancer screening is to be introduced, endoscopic examination of the large bowel needs to be easier to learn and significantly quicker to carry out. The 'Bladen system', first described in 1993, is a non-radiological method of visualising the path of the endoscope, using magnetic drive coils under the patient and a chain of sensors along the biopsy channel of the instrument. In 1998, results were published using a novel computer graphics system (the RMR system), in which a much more realistic image of the endoscope could be produced using the stored positional data from the Bladen system. The RMR system has been further refined to allow, for the first time ever, accurate measurement of the effect of the passage of a colonoscope along the bowel on the lengths of different segments of the large intestine. The results obtained in 232 patients undergoing colonoscopy are analysed. In 77 of the patients, a stiffening overtube is used to splint the sigmoid colon once the endoscope is at or beyond the splenic flexure. The mean time taken to pass the colonoscope across the transverse colon is significantly shorter (p < 0.001) when an overtube is used, despite it resulting in significant lengthening of the transverse colon. The routine use of a stiffening overtube can be expected to reduce the total procedure time by between 10 and 20%.