Sensitivity of 2DEG-based Hall-effect sensors at high temperatures.

The magnetic sensitivity of Hall-effect sensors made of InAlN/GaN and AlGaN/GaN heterostructures was measured between room temperature and 576 °C. Both devices showed decreasing voltage-scaled magnetic sensitivity at high temperatures, declining from 53 mV/V/T to 8.3 mV/V/T for the InAlN/GaN sample and from 89 mV/V/T to 8.5 mV/V/T for the AlGaN/GaN sample, corresponding to the decreasing electron mobility due to scattering effects at elevated temperatures. Alternatively, current-scaled sensitivities remained stable over the temperature range, only varying by 13.1% from the mean of 26.3 V/A/T and 10.5% from the mean of 60.2 V/A/T for the InAlN/GaN and AlGaN/GaN samples, respectively. This is due to the minimal temperature dependence of the electron sheet density on the 2-dimensional electron gas (2DEG). Both devices showed consistency in their voltage- and current-scaled sensitivity over multiple temperature cycles as well as nearly full recovery when returned to room temperature after thermal cycling. Additionally, an AlGaN/GaN sample held at 576 °C for 12 h also showed nearly full recovery at room temperature, further suggesting that GaN-based Hall-effect sensors are a good candidate for use in high temperature applications.

A nationwide investigation of radiation therapy event reporting-and-learning systems: Can standards be improved?

INTRODUCTION: Variation exists between event reporting-and-learning systems utilised in radiation therapy. Due to the impact of errors associated with this field of medicine, evidence-based and rigorous systems are imperative. The implementation of such systems facilitates the reactive enhancement of patient safety following an event. The purpose of this study was to evaluate Irish event reporting-and-learning procedures against the current literature using a developed evidence-based process map, and to propose recommendations as to how the national standard could be improved. METHODS: Radiation Therapy Service Managers of all Irish radiation therapy institutions (n = 12) were invited to participate in an anonymous online questionnaire. Included in the questionnaire was a reporting-and-learning process map developed from evidence-based literature, which was used to assess the institution's practice through the use of vignettes. Frequency analysis of closed-ended questions and thematic analysis of open-ended questions was performed to assess the data. RESULTS: A 91.7% response rate was achieved. The following areas were found to have the most variation with the evidence-based process map: event classification, external reporting, and dissemination of lessons-learned to a wider audience. Recommendations to standardise practice were made. CONCLUSION: Opportunities for improvement exist within event reporting-and-learning systems of Irish radiation therapy institutions and recommendations have been made on these. These findings can provide learning for other countries with similar reporting systems.

Pain vs comfort scores after Caesarean section: a randomized trial.

BACKGROUND: The use of negative words, such as 'sting' and 'pain', can increase patient pain and anxiety. We aimed to determine how pain scores compare with comfort scores and how the technique of pain assessment affects patient perceptions and experiences after operation. METHODS: After Caesarean section, 300 women were randomized before post-anaesthesia review. Group P women were asked to rate their pain on a 0-10-point verbal numerical rating scale (VNRS), where '0' was 'no pain' and '10' was 'worst pain imaginable'. Group C women were asked to rate comfort on a 0-10-point VNRS, where '0' was 'no comfort' and '10' was 'most comfortable'. All women were asked whether the Caesarean wound was bothersome, unpleasant, associated with tissue damage, and whether additional analgesia was desired. RESULTS: The median (inter-quartile range) VNRS pain scores was higher than inverted comfort scores at rest, 2 (1, 4) vs 2 (0.5, 3), P=0.001, and movement, 6 (4, 7) vs 4 (3, 5), P<0.001. Group P women were more likely to be bothered by their Caesarean section, had greater VNRS 'Bother' scores, 4 (2, 6) vs 1 (0, 3), P<0.001, perceived postoperative sensations as 'unpleasant' [relative risk (RR) 3.05, 95% confidence interval (CI) 2.20, 4.23], P<0.001, and related to tissue damage rather than healing and recovery (RR 2.03, 95% CI 1.30, 3.18), P=0.001. Group P women were also more likely to request additional analgesia (RR 4.33, 95% CI 1.84, 10.22), P<0.001. CONCLUSIONS: Asking about pain and pain scores after Caesarean section adversely affects patient reports of their postoperative experiences.

The pertussis epidemic: informing strategies for prevention of severe disease.

To assess the impact of Bordetella pertussis infections in South Australia during an epidemic and determine vulnerable populations, data from notification reports for pertussis cases occurring between July 2008 and December 2009 were reviewed to determine the distribution of disease according to specific risk factors and examine associations with hospitalizations. Although the majority (66%) of the 6230 notifications for pertussis occurred in adults aged >24 years, the highest notification and hospitalization rate occurred in infants aged <1 year. For these infants, factors associated with hospitalization included being aged <2 months [relative risk (RR) 2·3, 95% confidence interval (CI) 1·60-3·32], Indigenous ethnicity (RR 1·7, 95% CI 1·03-2·83) and receiving fewer than two doses of pertussis vaccine (RR 4·1, 95% CI 1·37-12·11). A combination of strategies aimed at improving direct protection for newborns, vaccination for the elderly, and reducing transmission from close contacts of infants are required for prevention of severe pertussis disease.

Assessment of block height for satisfactory spinal anaesthesia for caesarean section.

We investigated block heights that anaesthetists considered adequate for caesarean section to proceed under spinal anaesthesia. During 3 months, 15 obstetric anaesthetists recorded block height to touch, pinprick or cold when spinal anaesthesia was considered satisfactory for caesarean section to proceed. Median (IQR [range]) block height for touch, pinprick, first cold and icy were: T10 (T7-T12 [T3-L1]); T5 (T4-T6 [C7-L1]); T5 (T4-T6 [C7-L1]); and T3 (T2-T4 [C7-L1]), respectively. Modalities were significantly correlated for: touch and cold, p = 0.0001; touch and icy, p = 0.0007; touch and pinprick, p = 0.0018; cold and icy, p < 0.0001; cold and pinprick, p = 0.0001; icy and pinprick, p < 0.0001. Pairwise comparisons showed differences between all modalities (p < 0.001) apart from pinprick and first cold (p = 0.94). All women had satisfactory anaesthesia despite 76 (81%) having a block to touch below T6. Single modality assessment of block height, particularly using touch, may erroneously indicate inadequate anaesthesia for caesarean section.

A comparison of epidural and cerebrospinal fluid glucose in parturients at term: an observational study.

BACKGROUND: Detecting inadvertent dural puncture during labour epidural insertion can be difficult when using a loss of resistance to saline technique. Testing fluid for glucose that leaks from a Tuohy needle may confirm the presence of cerebrospinal fluid and infer inadvertent dural puncture. This study compared the glucose content of intrathecal fluid obtained during spinal anaesthesia for elective caesarean delivery with that of fluid from a Tuohy needle or epidural catheter when establishing epidural analgesia for labour. METHODS: Women aged ≥18 years undergoing elective caesarean delivery and labouring parturients who requested epidural analgesia were recruited prospectively in a tertiary referral centre over a three-month period. Fluid was collected into a sterile container either during spinal anaesthesia or from a labour epidural needle. Glucose content was evaluated using a bedside blood glucometer and laboratory colorimetric analyzer. RESULTS: Of the 118 women approached, 115 participated. All 40 women having spinal anaesthesia and 2/75 (2.7%) women having epidural analgesia, in whom inadvertent dural puncture was subsequently confirmed, had fluid samples testing positive for glucose. Median [range] laboratory glucose readings were 2.9 [1.3-5.1] mmol/L for cerebrospinal fluid and <0.3 mmol/L in fluid that leaked from a Tuohy needle (P=0.0001). CONCLUSION: When using a loss of resistance to saline technique for epidural catheter placement, bedside glucometer testing of fluid leaking from the epidural needle may be of value in the early detection of inadvertent dural puncture.

Activated clotting time as a screening test prior to catheter-based cardiovascular procedures.

The activated clotting time (ACT) was investigated as a rapid, inexpensive, point-of-service screening test for coagulation abnormalities prior to catheter-based procedures. A total of 963 patients were screened by obtaining a history, standard coagulation profile, and activated coagulation time. The prevalence of normal patients (normal ACT and coagulation profile) was 94% (sensitivity = 91%; specificity = 27%). A normal ACT had a positive predictive value of 95%. The ACT was an acceptable screening test due to its ability to predict positively a low rate of bleeding complication and normal coagulation studies. Patients with ACT > 150 sec should be further evaluated with a screening coagulation panel. Additionally, given its low specificity, coagulation studies should be obtained in high-risk patients since an abnormal ACT does not effectively correlate with abnormal coagulation studies.

Time-domain whole-field fluorescence lifetime imaging with optical sectioning.

A whole-field time-domain fluorescence lifetime imaging (FLIM) microscope with the capability to perform optical sectioning is described. The excitation source is a mode-locked Ti:Sapphire laser that is regeneratively amplified and frequency doubled to 415 nm. Time-gated fluorescence intensity images at increasing delays after excitation are acquired using a gated microchannel plate image intensifier combined with an intensified CCD camera. By fitting a single or multiple exponential decay to each pixel in the field of view of the time-gated images, 2-D FLIM maps are obtained for each component of the fluorescence lifetime. This FLIM instrument was demonstrated to exhibit a temporal discrimination of better than 10 ps. It has been applied to chemically specific imaging, quantitative imaging of concentration ratios of mixed fluorophores and quantitative imaging of perturbations to fluorophore environment. Initially, standard fluorescent dyes were studied and then this FLIM microscope was applied to the imaging of biological tissue, successfully contrasting different tissues and different states of tissue using autofluorescence. To demonstrate the potential for real-world applications, the FLIM microscope has been configured using potentially compact, portable and low cost all-solid-state diode-pumped laser technology. Whole-field FLIM with optical sectioning (3D FLIM) has been realized using a structured illumination technique.

Application of the stretched exponential function to fluorescence lifetime imaging.

Conventional analyses of fluorescence lifetime measurements resolve the fluorescence decay profile in terms of discrete exponential components with distinct lifetimes. In complex, heterogeneous biological samples such as tissue, multi-exponential decay functions can appear to provide a better fit to fluorescence decay data than the assumption of a mono-exponential decay, but the assumption of multiple discrete components is essentially arbitrary and is often erroneous. Moreover, interactions, both between fluorophores and with their environment, can result in complex fluorescence decay profiles that represent a continuous distribution of lifetimes. Such continuous distributions have been reported for tryptophan, which is one of the main fluorophores in tissue. This situation is better represented by the stretched-exponential function (StrEF). In this work, we have applied, for the first time to our knowledge, the StrEF to time-domain whole-field fluorescence lifetime imaging (FLIM), yielding both excellent tissue contrast and goodness of fit using data from rat tissue. We note that for many biological samples for which there is no a priori knowledge of multiple discrete exponential fluorescence decay profiles, the StrEF is likely to provide a truer representation of the underlying fluorescence dynamics. Furthermore, fitting to a StrEF significantly decreases the required processing time, compared with a multi-exponential component fit and typically provides improved contrast and signal/noise in the resulting FLIM images. In addition, the stretched-exponential decay model can provide a direct measure of the heterogeneity of the sample, and the resulting heterogeneity map can reveal subtle tissue differences that other models fail to show.

Uterine artery embolization for the treatment of adenomyosis: clinical response and evaluation with MR imaging.

OBJECTIVE: This study was performed to evaluate the MR imaging appearance and clinical response of patients undergoing uterine artery embolization for the treatment of menorrhagia due to adenomyosis. MATERIALS AND METHODS: A retrospective review of 15 patients with adenomyosis and menorrhagia who underwent uterine artery embolization was performed. The diagnosis of adenomyosis was based on established MR imaging criteria. Clinical response was assessed at a minimum of 3 months after embolization. Follow-up MR imaging was performed 6 months after embolization. RESULTS: Of the 15 patients in this study, five had diffuse adenomyosis without evidence of uterine fibroids, one had focal adenomyosis without evidence of uterine fibroids, and the remaining nine had adenomyosis with one or more fibroids. At follow-up, 12 (92.3%) of the 13 patients reported significant improvement in presenting symptoms and quality of life. One patient continued experiencing menorrhagia, and one patient experienced amenorrhea during the 5 months of follow-up after embolization. MR imaging in nine patients, performed at a mean of 5.9 months after embolization, revealed significant reductions in median uterine volume (42%), median fibroid volume (71%), and mean-junctional-zone thickness (11 mm; 33%; p < 0.5). Six of the nine patients had subendometrial regions of decreased T2 signal intensity after embolization. CONCLUSION: Uterine artery embolization is a promising nonsurgical alternative for patients with menorrhagia and adenomyosis. Significant improvement in presenting symptoms and in quality of life is associated with decreases in uterine size and junctional zone thickness. Larger prospective studies are needed to establish the safety and efficacy of this procedure for patients with adenomyosis.

Protein synthesis costs could account for the tissue-specific effects of sub-lethal copper on protein synthesis in rainbow trout (Oncorhynchus mykiss).

This study investigates protein synthesis, following exposure to sub-lethal Cu, in rainbow trout in vivo and in vitro. The investigation has two aims: to determine if perturbations in protein synthesis, compared with other physiological changes, are a biomarker of Cu pollution and to evaluate the most productive role of cellular models in ecotoxicology. Protein synthesis rates were measured by labelling with 3H-phenylalanine. In vivo this was applied by a single (i.p.) injection and in vitro by bathing the cells in 3H-phenylalanine labelled culture media. The effects in vivo were tissue specific. After 3 weeks' exposure to 0.7 microM Cu only skin protein synthesis was reduced. Gills and liver from the same fish were unaffected. This reduction in skin protein synthesis appears to be more sensitive than some other biomarkers reported in the literature. However, Cu concentrations greater by orders of magnitude were required to reproduce this reduction in protein synthesis in skin cell explants (200 and 400 microM). Hepatocyte protein synthesis was unaffected by 10, 20 and 40 microM Cu and a separate investigation has also shown that 25 and 75 microM Cu does not effect protein synthesis in cultured gill cells. Oxygen consumption rates were also measured in vitro by monitoring the decline in O2 partial pressure. The Cu concentrations given above resulted in a decline in O2 consumption rates in the respective cell types. By measuring protein synthesis and O2 consumption after treatment with a protein synthesis inhibitor (cycloheximide), the costs of protein synthesis were also determined. Synthesis costs in hepatocytes are close to the theoretical minimum and are only marginally affected by Cu. Gill cell synthesis costs are also minimal and are unaffected. In skin explants, the reduction in protein synthesis was accompanied by greatly increased synthesis costs. This in vitro result offers a hypothesis as to the tissue-specific effects in vivo; i.e. the energetic demand of protein synthesis may determine tissue sensitivity or susceptibility. Cell or tissue types with high protein synthesis rates are able to avoid detrimental increases in the synthesis cost when exposed to Cu. In tissues with a low protein synthesis rate any further reduction is more likely to incur a potentially damaging increase in protein synthesis costs. Thus, whilst in vitro models may have little practical use in environmental monitoring, they may be best used as a mechanistic tool in understanding susceptibility or tolerance to sub-lethal Cu.

The further development of rainbow trout primary epithelial cell cultures as a diagnostic tool in ecotoxicology risk assessment.

The use of short-term cytotoxicity assays for the initial screening of chemicals not only aids in establishing priorities for the selection of chemicals that should be tested in vivo, but also decreases the time in which potential toxicants can be valued. Rainbow trout primary skin epithelial cell cultures are one such assay. Rainbow trout primary skin cell cultures contain two cell types, keratinocytes and goblet mucus cells. Two aquatic pollutants, copper and prochloraz were screened using this cell system. The influence of media composition on the effects of the aquatic pollutants was also studied by testing the chemicals in both serum-containing and serum-free medium and the morphological changes that occurred within the cell cultures recorded. The concentration of copper that causes a reduction of 90% in the residual of day 3 growth of the primary cell culture system was found to be approximately 10 fold more than that of prochloraz. Prochloraz was found to cause a greater reduction in growth area when added to the primary cell culture system in serum-free medium than in serum-containing medium. Copper, in contrast, was found to exert reduced toxicity when added to the test cultures in serum-free medium compared with addition in serum-containing medium. Prochloraz was found to kill the epithelial cells by a process of necrosis. Copper, was found to kill the epithelial cells by both necrosis and apoptosis in a ratio of 2:1. It was also observed that as the dose of both chemicals increased, the number of goblet cells contained in the cell cultures decreased. A PAS stain was carried out to determine if the goblet cells were exocytosing their contents onto the cell culture surface. It was found that as chemical exposure increased the number of cells expressing positivity for mucus also increased. The results of this study add further evidence to support that primary cell cultures are a very appropriate model for toxicity risk assessment.

Leucocyte populations in respiratory syncytial virus-induced bronchiolitis.

OBJECTIVES: To enumerate the cellular composition of the airways in infants with acute bronchiolitis. METHODOLOGY: Cells were obtained by airway lavage from the upper and lower airway and the peripheral blood of infants with respiratory syncytial virus (RSV)+ bronchiolitis, RSV- bronchiolitis and age-matched controls. RESULTS: Neutrophils are the predominant cells present in the upper and lower airway. Neutrophils are present at a higher number/unit volume in the airway than in the peripheral blood. CONCLUSIONS: Neutrophils, being the dominant cellular infiltrate into the airway, are likely to contribute to the pathophysiology of bronchiolitis. Therapies targeted at limiting neutrophil influx or neutrophil-mediated damage in the airway may have a therapeutic role.

Attenuation of somatosensory evoked potentials during positioning in a patient undergoing suboccipital craniectomy for Chiari I malformation with syringomyelia.

Intraoperative electrophysiologic monitoring can diminish the risk of neurologic injury by enabling the detection of injury at a time when it can be reversed or minimized. This report describes a 14-year-old girl with a Chiari's malformation type I and syringomyelia who underwent a suboccipital decompression and dural patch grafting with concurrent somatosensory evoked potentials. When the patient was turned into the prone position and the neck was flexed, the left-sided somatosensory evoked potential deteriorated. After the patient's neck was repositioned, the left median nerve potential improved but did not return to baseline. Postoperatively, the patient had decreased proprioception of her left arm, which completely resolved at 2-week follow-up. This single case report does not establish the need for routine somatosensory evoked potential monitoring. Nevertheless, deterioration of the potential in this case led directly to a change in the surgical positioning, which may have significantly reduced the chances of a permanent neurologic injury.

Lung function, permeability, and surfactant composition in oleic acid-induced acute lung injury in rats.

Although acute lung injury (ALI) is associated with inflammation and surfactant dysfunction, the precise sequence of these changes remains poorly described. We used oleic acid to study the pathogenesis of ALI in spontaneously breathing anesthetized rats. We found that lung pathology can occur far more rapidly than previously appreciated. Lung neutrophils were increased approximately threefold within 5 min, and surfactant composition was dramatically altered within 15 min. Alveolar cholesterol increased by approximately 200%, and even though disaturated phospholipids increased by approximately 30% over 4 h, the disaturated phospholipid-to-total phospholipid ratio fell. Although the alveolocapillary barrier was profoundly disrupted after just 15 min, with marked elevations in lung fluid ((99m)Tc-labeled diethylenetriamine pentaacetic acid) and (125)I-labeled albumin flux, the lung rapidly began to regain its sieving properties. Despite the restoration in lung permeability, the animals remained hypoxic even though minute ventilation was increased approximately twofold and static compliance progressively deteriorated. This study highlights that ALI can set in motion a sequence of events continuing the respiratory failure irrespective of the alveolar surfactant pool size and the status of the alveolocapillary barrier.

Outpatient uterine artery embolization for symptomatic uterine fibroids: experience in 49 patients.

PURPOSE: To assess the feasibility of performing uterine artery embolization as an outpatient treatment for symptomatic uterine fibroids. MATERIALS AND METHODS: Forty-nine consecutive patients (mean age, 44.5 years; range, 28-54 years) underwent uterine artery embolization during a 12-month period. Embolization was performed with 350-500 microm polyvinyl alcohol particles (44 of 49) or Gelfoam pledgets (five of 49). At discharge, patients were given instructions regarding the constitutional symptoms to expect after embolization. A specific medication regimen consisting of prochlorperazine, ketorolac, meperidine, and hydrocodone was prescribed for relief of these symptoms. All patients were telephoned within 24 hours of discharge. During long-term follow-up, a questionnaire was administered to all patients to evaluate the periprocedural experience. Three-month clinical follow-up was available in 26 patients and 6-month imaging follow-up was available in 16 patients. RESULTS: Fourteen patients presented with menorrhagia, six had bulk-related symptoms (abdominal distension, stress incontinence, pelvic pain), and 29 had both. Technical success for bilateral embolization was 98%. Forty-seven of 49 patients were discharged to home 6-8 hours after the procedure; two patients required overnight observation in an ambulatory unit (one because of postprocedure hypertension and one because of a late procedure completion time). At the first follow-up phone call, reported symptoms included pelvic pain/cramping in 83.7% (41 of 49), fatigue in 75.5% (37 of 49), nausea/vomiting in 46.9% (23 of 49), and a nonpurulent vaginal discharge in 18.4% (nine of 49). These symptoms were satisfactorily controlled with discharge medications in 48 of 49 patients. No patients returned to the hospital or visited an emergency room during the first 48 hours after discharge. Forty-six of 49 patients were satisfied with the decision for home discharge. The average uterine volume reduction in 16 patients with 6-month imaging follow-up was 47.5%; 88.5%, of patients (23 of 26) with 3-month clinical follow-up reported improvement or elimination of symptoms. CONCLUSION: With defined telephone follow-up, staff availability, and a protocol designed to alleviate the postprocedure constitutional symptoms, uterine artery embolization is both safe and effective when performed as an outpatient procedure.