Exploration of the phase diagram of liquid water in the low-temperature metastable region using synthetic fluid inclusions.

We present new experimental data of the low-temperature metastable region of liquid water derived from high-density synthetic fluid inclusions (996-916 kg m-3) in quartz. Microthermometric measurements include: (i) prograde (upon heating) and retrograde (upon cooling) liquid-vapour homogenisation. We used single ultrashort laser pulses to stimulate vapour bubble nucleation in initially monophase liquid inclusions. Water densities were calculated based on prograde homogenisation temperatures using the IAPWS-95 formulation. We found retrograde liquid-vapour homogenisation temperatures in excellent agreement with IAPWS-95. (ii) Retrograde ice nucleation. Raman spectroscopy was used to determine the nucleation of ice in the absence of the vapour bubble. Our ice nucleation data in the doubly metastable region are inconsistent with the low-temperature trend of the spinodal predicted by IAPWS-95, as liquid water with a density of 921 kg m-3 remains in a homogeneous state during cooling down to a temperature of -30.5 °C, where it is transformed into ice whose density corresponds to zero pressure. (iii) Ice melting. Ice melting temperatures of up to 6.8 °C were measured in the absence of the vapour bubble, i.e. in the negative pressure region. (iv) Spontaneous retrograde and, for the first time, prograde vapour bubble nucleation. Prograde bubble nucleation occurred upon heating at temperatures above ice melting. The occurrence of prograde and retrograde vapour bubble nucleation in the same inclusions indicates a maximum of the bubble nucleation curve in the ϱ-T plane at around 40 °C. The new experimental data represent valuable benchmarks to evaluate and further improve theoretical models describing the p-V-T properties of metastable water in the low-temperature region.

Anti-PSMA antibody-coupled gold nanorods detection by optical and electron microscopies.

While cancer is one of the greatest challenges to public health care, prostate cancer was chosen as cancer model to develop a more accurate imaging assessment than those currently available. Indeed, an efficient imaging technique which considerably improves the sensitivity and specificity of the diagnostic and predicting the cancer behavior would be extremely valuable. The concept of optoacoustic imaging using home-made functionalized gold nanoparticles coupled to an antibody targeting PSMA (prostate specific membrane antigen) was evaluated on different cancer cell lines to demonstrate the specificity of the designed platform. Two commonly used microscopy techniques (indirect fluorescence and scanning electron microscopy) showed their straightforwardness and versatility for the nanoparticle binding investigations regardless the composition of the investigated nanoobjects. Moreover most of the research laboratories and centers are equipped with fluorescence microscopes, so indirect fluorescence using Quantum dots can be used for any active targeting nanocarriers (polymers, ceramics, metals, etc.). The second technique based on backscattered electron is not only limited to gold nanoparticles but also suits for any study of metallic nanoparticles as the electronic density difference between the nanoparticles and binding surface stays high enough. Optoacoustic imaging was finally performed on a 3D cellular model to assess and prove the concept of the developed platform.

Ciliary beating plane and wave propagation in the bovine oviduct.

The uterine tube is an essential conduit for the gametes and zygote during reproduction. The necessary bidirectional conveyance occurs through peristalsis and ciliary activity, but unlike in respiratory tract, little is known about mucociliary transport in the uterine tube, and the direction of transport and the alignment of oviductal cilia have not been conclusively characterized. This study aimed to determine the uniformity in the axonemal orientation of motile cilia in the bovine uterine tube, to identify the direction of mucociliary transport and to relate the presumptive beating plane and the mucociliary transport direction to the long axis of the uterine tube. The angular spread of oviductal motile cilia was determined by electron microscopy, and by maintaining the accurate alignment of the samples throughout the processing steps, axonemal orientation was determined relative to the long axis of the oviduct. The direction of the effective mucociliary transport was determined by the analysis of video microscopic data recorded on explants. Vector-based analysis of electron micrographs yielded the mean angle of deviation between the 'effective ciliary stroke', as derived from axonemal orientation, and the tubal longitudinal axis pointing towards the uterus to be 0.8°, with a standard deviation of 35.2°. The corresponding angular deviation of the short-wave propagation was -6.8° (SD 34.6°). These results show that oviductal motile cilia are rigorously aligned, that the beating plane of the cilia is parallel to the long axis of the uterine tube and that the 'effective stroke' and mucociliary transport are directed towards the uterus.

Improved contrast deep optoacoustic imaging using displacement-compensated averaging: breast tumour phantom studies.

For real-time optoacoustic (OA) imaging of the human body, a linear array transducer and reflection mode optical irradiation is usually preferred. Such a setup, however, results in significant image background, which prevents imaging structures at the ultimate depth determined by the light distribution and the signal noise level. Therefore, we previously proposed a method for image background reduction, based on displacement-compensated averaging (DCA) of image series obtained when the tissue sample under investigation is gradually deformed. OA signals and background signals are differently affected by the deformation and can thus be distinguished. The proposed method is now experimentally applied to image artificial tumours embedded inside breast phantoms. OA images are acquired alternately with pulse-echo images using a combined OA/echo-ultrasound device. Tissue deformation is accessed via speckle tracking in pulse echo images, and used to compensate in the OA images for the local tissue displacement. In that way, OA sources are highly correlated between subsequent images, while background is decorrelated and can therefore be reduced by averaging. We show that image contrast in breast phantoms is strongly improved and detectability of embedded tumours significantly increased, using the DCA method.

Vapor bubble generation around gold nano-particles and its application to damaging of cells.

We investigated vapor bubbles generated upon irradiation of gold nanoparticles with nanosecond laser pulses. Bubble formation was studied both with optical and acoustic means on supported single gold nanoparticles and single nanoparticles in suspension. Formation thresholds determined at different wavelengths indicate a bubble formation efficiency increasing with the irradiation wavelength. Vapor bubble generation in Bac-1 cells containing accumulations of the same particles was also investigated at different wavelengths. Similarly, they showed an increasing cell damage efficiency for longer wavelengths. Vapor bubbles generated by single laser pulses were about half the cell size when inducing acute damage.

Tight contact technique during side-to-side laser tissue soldering of rabbit aortas improves tensile strength.

BACKGROUND: Cerebral revascularization may be indicated either for blood flow preservation or flow augmentation, often in clinical situations where neither endovascular nor standard surgical intervention can be performed. Cerebral revascularization can be performed by using a temporary occlusive or a non-occlusive technique. Both of these possibilities have their specific range of feasibility. Therefore non-occlusive revascularization techniques have been developed. To further reduce the risks for patients, less time consuming, sutureless techniques such as laser tissue soldering are currently being investigated. METHOD: In the present study, a new technique for side-to-side anastomosis was developed. Using a "sandwich technique", two vessels are kept in close contact during the laser soldering. Thoraco-abdominal aortas from 24 different rabbits were analyzed for laser irradiation induced tensile strength. Two different irradiation modes (continuous and pulsed) were used. The results were compared to conventional, noncontact laser soldering. Histology was performed using HE, Mason's Trichrome staining. FINDINGS: The achieved tensile strengths were significantly higher using the close contact "sandwich technique" as compared to the conventional adaptation technique. Furthermore, tensile strength was higher in the continuously irradiated specimen as compared to the specimen undergoing pulsed laser irradiation. The histology showed similar denaturation areas in both groups. The addition of a collagen membrane between vessel components reduced the tensile strength. CONCLUSION: These first results proved the importance of close and tight contact during the laser soldering procedure thus enabling the development of a "sandwich laser irradiation device" for in vivo application in the rabbit.

Onset of submarine debris flow deposition far from original giant landslide.

Submarine landslides can generate sediment-laden flows whose scale is impressive. Individual flow deposits have been mapped that extend for 1,500 km offshore from northwest Africa. These are the longest run-out sediment density flow deposits yet documented on Earth. This contribution analyses one of these deposits, which contains ten times the mass of sediment transported annually by all of the world's rivers. Understanding how this type of submarine flow evolves is a significant problem, because they are extremely difficult to monitor directly. Previous work has shown how progressive disintegration of landslide blocks can generate debris flow, the deposit of which extends downslope from the original landslide. We provide evidence that submarine flows can produce giant debris flow deposits that start several hundred kilometres from the original landslide, encased within deposits of a more dilute flow type called turbidity current. Very little sediment was deposited across the intervening large expanse of sea floor, where the flow was locally very erosive. Sediment deposition was finally triggered by a remarkably small but abrupt decrease in sea-floor gradient from 0.05 degrees to 0.01 degrees. This debris flow was probably generated by flow transformation from the decelerating turbidity current. The alternative is that non-channelized debris flow left almost no trace of its passage across one hundred kilometres of flat (0.2 degrees to 0.05 degrees) sea floor. Our work shows that initially well-mixed and highly erosive submarine flows can produce extensive debris flow deposits beyond subtle slope breaks located far out in the deep ocean.

Functional imaging of mucociliary phenomena: high-speed digital reflection contrast microscopy.

We present a technique for the investigation of mucociliary phenomena on trachea explants under conditions resembling those in the respiratory tract. Using an enhanced reflection contrast, we detect simultaneously the wave-like modulation of the mucus surface by the underlying ciliary activity and the transport of particles embedded in the mucus layer. Digital recordings taken at a speed of 500 frames per second are analyzed by a set of refined data processing algorithms. The simultaneously extracted data include not only ciliary beat frequency and its surface distribution, but also space-time structure of the mucociliary wave field, wave velocity and mucus transport velocity. Furthermore, we propose the analysis of the space and time evolution of the phase of the mucociliary oscillations to be the most direct way to visualize the coordination of the cilia. In particular, this analysis indicates that the synchronization is restricted to patches with varying directions of wave propagation, but the transport direction is strongly correlated with the mean direction of waves. The capabilities of the technique and of the data-processing algorithms are documented by characteristic data obtained from mammalian and avine tracheae.

Quality of psychomotor recovery after propofol sedation for routine endoscopy: a randomized and controlled study.

BACKGROUND AND STUDY AIMS: Propofol sedation is increasingly being used for endoscopy in the outpatient setting. In view of the agent's short period of action, current recommendations that patients should avoid driving or using public transport unescorted for 24 h may be too strict. Psychomotor recovery and driving skills before and after sedation were therefore assessed. PATIENTS AND METHODS: A total of 100 patients undergoing routine upper or lower gastrointestinal endoscopy were randomly sedated either with propofol alone or with midazolam plus pethidine. The recovery time and quality of recovery were assessed. Psychomotor recovery was evaluated using the number connection test (NCT) and a driving simulator test 1 h before and 2 h after the endoscopic procedure. RESULTS: Ninety-six patients completed the 2-hour post-sedation procedure. Vital signs were recorded, and no clinically relevant complications occurred. The mean recovery time and quality of recovery were significantly better after propofol sedation (14 +/- 9 min vs. 25 +/- 8 min and 8.7 +/- 1.3 vs. 6.3 +/- 1.1 points) ( P < 0.01). Psychomotor and driving skills after propofol sedation were similar to the baseline results, while in the midazolam/pethidine group, patients showed significantly more lane deviations (1.1 +/- 0.9 vs. 1.6 +/- 0.9), time over the speed limit (0.3 +/- 0.83 vs. 0.6 +/- 0.88), missed stoplights more often (0.05 +/- 0.31 vs. 0.11 +/- 0.35), and had slower reaction times for unexpected events (1.11 +/- 0.46 s vs. 1.39 +/- 0.44 s) ( P < 0.01). The time needed to complete the NCT after sedation did not differ between the two groups (32.1 +/- 12.0 s vs. 33.4 +/- 12.6 s for propofol; 31.5 +/- 11.2 s vs. 34.6 +/- 12.8 s for midazolam/pethidine). CONCLUSIONS: Current recommendations that patients should refrain from driving and unescorted use of public transport for 24 h after sedation may need to be reconsidered in patients who receive propofol sedation.

Intraductal ultrasonography in the diagnosis of Mirizzi syndrome.

BACKGROUND AND STUDY AIMS: Common bile duct (CBD) compression can be caused by stones in the cystic duct (Mirizzi syndrome) which can be difficult to diagnose even with endoscopic retrograde cholangiopancreatography (ERCP). Conventional imaging often gives insufficient information and endoscopic ultrasonography (EUS) and magnetic resonance imaging may improve diagnostic accuracy, but often the final diagnosis is made during exploratory surgery. PATIENTS AND METHODS: All patients undergoing ERCP during a 3-year period were prospectively analyzed if they fulfilled the inclusion criteria: gallbladder in situ; obstructive jaundice with CBD stenosis, demonstrated at endoscopic retrograde cholangiography (ERC), but unexplained at ultrasonography; and inability to demonstrate the cystic duct during ERC. Intraductal ultrasonography (IDUS) was carried out over a guide wire using a 20-MHz probe. Prior to ERCP, patients were evaluated with abdominal ultrasonography and computed tomography (CT), as well as by magnetic resonance cholangiopancreatography (MRCP) or EUS in some. RESULTS: 74 patients out of 2089 undergoing ERCP fulfilled the entry criteria. Final diagnoses, from surgical exploration (n = 41), cytology (n = 21), or endoscopic extraction of stones from the cystic duct (n = 12), were Mirizzi syndrome (type I) in 30 patients and other causes in 44 patients (gallbladder carcinoma [n = 16], pancreatic carcinoma [n = 9], metastatic compression [n = 9], other [n = 10]). CT had shown suspected Mirizzi syndrome in 1/30 cases (3 %) and MRCP in 12/19 evaluated cases (63 %). EUS allowed a correct diagnosis in 11 of 15 evaluated cases (73 %). IDUS required an additional 8 +/- 3 min and showed a sensitivity of 97 % and specificity of 100 %. CONCLUSION: IDUS is a sensitive and specific method for the diagnosis of Mirizzi syndrome.

Treatment of haemorrhagic radiation-induced proctopathy using small volume topical formalin instillation.

BACKGROUND: Between 2 and 5% of patients undergoing pelvic radiotherapy develop chronic radiation proctopathy, occurring as a result of damage to the rectal mucosa during the treatment. Rectal bleeding of varying severity can occur as a consequence. There have been no formal trials of treatment for haemorrhagic radiation proctopathy and a variety of methods are currently used. AIM: In a retrospective study of 20 patients treated at a single centre, we assessed the efficacy of small volume topical formalin instillation to control bleeding from radiation proctopathy. METHOD: Patients were treated by a single operator using 20 mL of a 5% solution of formalin instilled into the rectum via a flexible sigmoidoscope for 3 min. Patients were followed up for an average of 22.7 months (range: 2-69). RESULTS: A single session of formalin treatment was effective in 13 of 20 (65%) patients and a further four (20%) patients responded to a second treatment. No complications of the treatment was identified. CONCLUSION: Small volume formalin instillation therapy appears to be safe and effective in the context of haemorrhagic radiation proctopathy. The technique is simple, inexpensive, quick and requires no sedation. We suggest that it should be considered as a first line for patients presenting with this distressing condition.

A comparison of laser-ultrasound detection system sensitivity with a broad-band ultrasonic source for biomedical applications.

BACKGROUND: Laser ultrasound detection systems are used for noninvasive imaging of internal structures and function of soft tissues. The detection systems with a high sensitivity can be used for detecting small tumors located deeply in human tissues, such as the breast. In this study, the sensitivity of existing ultrasonic detection systems has been compared experimentally by using thermoelastic waves as a broadband ultrasonic source. METHODS: For the comparison, an optical stress transducer, a polyvinylidene difluoride (PVDF) sheet and a calibrated PVDF needle hydrophone were used. To ensure that all detection systems were interrogated by the same ultrasonic field, a small optical instrument was constructed to fix the generating laser head. The sensitivity was evaluated by measuring signal-to-noise ratios (SNRs) and noise equivalent pressures (NEPs). RESULTS: The PVDF system, with a 4 kPa NEP, has a 22-dB better performance than the optical stress transducer. The optical stress transducer showed nearly the same sensitivity as the hydrophone for detecting ultrasound waves at a 1-cm distance. CONCLUSIONS: PVDF detection system provides a useful tool for imaging of soft tissues because of its high sensitivity and broadband detection range.

Reduction of miss rates of colonic adenomas by zoom chromoendoscopy.

BACKGROUND AND AIMS: The aim of this study was to determine the detection rate of polyps using zoom chromoendoscopy (ZE) compared with standard video colonoscopy. PATIENTS AND METHODS: End-to-end colonoscopies were performed in 50 patients by two different endoscopists blinded for each other's results. Lesions detected during initial standard colonoscopy (C1) were biopsied or removed by snare resection. The second colonoscopy (C2) was done with a zoom colonoscope spraying the whole colon with indigocarmine (0.4%). In addition, detected mucosal lesions were documented prior to ZE and then classified according to the pit pattern classification before biopsy or removal. The retrieval time for each procedure was determined. RESULTS: The average retrieval time for C1 was 13+/-9 min (9-24) and 28+/-11 min (16-38, p<0.05) for ZE. During C1, 56 lesions were detected in 26 of 50 patients (34 hyperplastic and 22 adenomatous). During C2, 19 additional polyps were documented prior to ZE (15% tandem miss rate), and 20 further lesions were detected with ZE (21% additional polyp detection rate compared to C1 and C2 without ZE). Of the 39 additional lesions removed during C2 after ZE, 29 were hyperplastic and 10 were adenomatous. Most adenomas detected during the second investigation were found in patients in whom adenomatous polyps had already been removed during the initial colonoscopy (9 of 26 patients vs 1 of 24 patients, p<0.02). No carcinoma was detected. The pit pattern classification allowed a correct differentiation between hyperplastic and adenomatous polyps (accuracy 93%, sensitivity 90%, specificity 97%). CONCLUSION: Using zoom chromoendoscopy, the rate of detecting colonic polyps can be increased at the cost of a longer retrieval time.

Unusual malfunction of percutaneous endoscopic jejunostomy feeding tubes in patients with intestinal dysmotility.

We report the complication of knotted percutaneous endoscopic jejunostomy (PEJ) feeding tubes in three patients with intestinal dysmotility. The management of PEJ tube dysfunction and strategies to prevent this complication are discussed.

Reducing delays in the diagnosis and treatment of Clostridium difficile diarrhoea.

BACKGROUND: The diagnosis of Clostridium difficile diarrhoea is often delayed. AIM: To assess and reduce delays in diagnosis and treatment. DESIGN: Two-part study: retrospective audit then prospective observational. METHODS: The retrospective study audited cases positive for C. difficile culture or toxin A between June 2000 and January 2001. Cases were reviewed regarding demographic characteristics and the timing from onset of symptoms to testing and treatment (n = 27). In the prospective study, efforts were made to increase the awareness of medical staff about C. difficile diarrhoea, and testing for C. difficile toxin A assay was substituted for stool culture and external toxin analysis. Data were prospectively analysed for demographic characteristics and time from onset of symptoms to testing and treatment (n = 24). RESULTS: There were no significant differences in age (76 vs. 78 years), male to female ratio (1:2 vs. 1:4), reason for admission, specialty responsible, or mortality rate (40% vs. 37%) during the presenting admission. Preceding antibiotic use, the combination of antibiotics used and subsequent treatment also did not differ between groups. The time from onset of diarrhoea to sampling was reduced from 4.7 days (range 3-30) to 0.8 days (range 0-5; p