Weaning from mechanical ventilation in intensive care units across 50 countries (WEAN SAFE): a multicentre, prospective, observational cohort study

BACKGROUND

Current management practices and outcomes in weaning from invasive mechanical ventilation are poorly understood. We aimed to describe the epidemiology, management, timings, risk for failure, and outcomes of weaning in patients requiring at least 2 days of invasive mechanical ventilation.

METHODS

WEAN SAFE was an international, multicentre, prospective, observational cohort study done in 481 intensive care units in 50 countries. Eligible participants were older than 16 years, admitted to a participating intensive care unit, and receiving mechanical ventilation for 2 calendar days or longer. We defined weaning initiation as the first attempt to separate a patient from the ventilator, successful weaning as no reintubation or death within 7 days of extubation, and weaning eligibility criteria based on positive end-expiratory pressure, fractional concentration of oxygen in inspired air, and vasopressors. The primary outcome was the proportion of patients successfully weaned at 90 days. Key secondary outcomes included weaning duration, timing of weaning events, factors associated with weaning delay and weaning failure, and hospital outcomes. This study is registered with ClinicalTrials.gov, NCT03255109.

FINDINGS

Between Oct 4, 2017, and June 25, 2018, 10 232 patients were screened for eligibility, of whom 5869 were enrolled. 4523 (77·1%) patients underwent at least one separation attempt and 3817 (65·0%) patients were successfully weaned from ventilation at day 90. 237 (4·0%) patients were transferred before any separation attempt, 153 (2·6%) were transferred after at least one separation attempt and not successfully weaned, and 1662 (28·3%) died while invasively ventilated. The median time from fulfilling weaning eligibility criteria to first separation attempt was 1 day (IQR 0-4), and 1013 (22·4%) patients had a delay in initiating first separation of 5 or more days. Of the 4523 (77·1%) patients with separation attempts, 2927 (64·7%) had a short wean (≤1 day), 457 (10·1%) had intermediate weaning (2-6 days), 433 (9·6%) required prolonged weaning (≥7 days), and 706 (15·6%) had weaning failure. Higher sedation scores were independently associated with delayed initiation of weaning. Delayed initiation of weaning and higher sedation scores were independently associated with weaning failure. 1742 (31·8%) of 5479 patients died in the intensive care unit and 2095 (38·3%) of 5465 patients died in hospital.

INTERPRETATION

In critically ill patients receiving at least 2 days of invasive mechanical ventilation, only 65% were weaned at 90 days. A better understanding of factors that delay the weaning process, such as delays in weaning initiation or excessive sedation levels, might improve weaning success rates.

FUNDING

European Society of Intensive Care Medicine, European Respiratory Society.

Drone versus ambulance for blood products transportation: an economic evaluation study

BACKGROUND

Medical transportation is an essential step in health care services, and includes ground, air and water transportation. Among the important uses of medical transportation is the delivery of blood products in the event of a clinical emergency. Drone technology is the latest technological advancement that may revolutionize medical transportation globally. Nonetheless, its economic evaluation is scant and insufficient, whilst its cost-effectiveness remains controversial. The aim of this study was to compare the cost-effectiveness of drone transportation versus the ambulance.

METHODS

The setting of the study was within a developing nation. An economic evaluation study of drone versus ambulance for emergency blood products transportation between the Sabah Women and Children Hospital (SWACH) and the Queen Elizabeth II Hospital (QEH2) on Borneo Island was conducted using the Cost-Effectiveness Analysis (CEA) technique. The total cost of each mode of transportation was calculated using the Activity Based Costing (ABC) method. Travel time was used as a denominator to estimate the Incremental Cost Effectiveness Ratio (ICER).

RESULTS

For one clinical emergency in SWACH, a round trip of blood products transportation from SWACH to QEH2 costs RM1,266.02 (USD307.09) when using the ambulance, while the drone costs RM1,313.28 (USD319.36). The travel time for the drone was much shorter (18 min) compared to the ambulance (34 min). The Cost-Effectiveness Ratio (CER) of ambulance transportation was RM37.23 (USD9.05) per minute whilst the CER of drone transportation was RM72.96 (USD17.74) per minute. The ICER of drone versus ambulance was - 2.95, implying an increase of RM2.95 in cost for every minute saved using a drone instead of an ambulance.

CONCLUSION

Although drone transportation of blood products costs more per minute compared to the ambulance, the significantly shorter transport time of the drone offset its cost. Thus, we believe there is good economic potential for drone usage for blood products transportation in developing nations particularly if the drone price decreases and its operational lifespan increases. Our limitation of a non-clinical denominator used in this study leads to the recommendation for use of clinical outcomes in future studies.

184 Effects of The Coronavirus Pandemic on Medical and Surgical Education: Results of An International Survey by The International Association of Student Surgical Societies (IASSS)

Aim

Coronavirus disease 2019 (COVID-19) presents a variety of unforeseen challenges to medical students and surgical trainees. Adaptations to the content and delivery of medical education are inevitable as institutions respond to the virus. Departments face significant restructuring, with important implications for training. Our aim was to assess the global impact of the first wave of COVID-19 on medical and surgical education.

Method

Between 12 May and 26 May 2020, an online survey was conducted and circulated to contacts of the International Association of Student Surgical Societies, including medical students and healthcare practitioners. All data were anonymous; no personal identifiable information was collected. Consent was implied by participation in the survey, which was on a voluntary basis.

Results

We collated 527 responses from 111 institutions across 26 countries. Globally, 93.5% of medical student placements were affected by the first wave of COVID-19, with examination restructuring and alternative teaching methods employed by 87.8% of medical schools. Trainee redeployment was common in both surgical (61.5%) and non-surgical (77.1%) disciplines. Surgical services were significantly affected, with reduced elective procedures in 93% of institutions. On an individual level, COVID-19 resulted in prolonged absence from clinical duties and mental health concerns at all levels of training.

Conclusions

Our data highlight drastic changes in medical and surgical education and practice as a result of the first wave of COVID-19. These changes are significant at all levels of training, both institutionally and individually. The pandemic is likely to have persistent consequences for future trainees in terms of education and career progression.

Tipping the immunostimulatory and inhibitory DAMP balance to harness immunogenic cell death

Induction of tumor cell death is the therapeutic goal for most anticancer drugs. Yet, a mode of drug-induced cell death, known as immunogenic cell death (ICD), can propagate antitumoral immunity to augment therapeutic efficacy. Currently, the molecular hallmark of ICD features the release of damage-associated molecular patterns (DAMPs) by dying cancer cells. Here, we show that gemcitabine, a standard chemotherapy for various solid tumors, triggers hallmark immunostimualtory DAMP release (e.g., calreticulin, HSP70, and HMGB1); however, is unable to induce ICD. Mechanistic studies reveal gemcitabine concurrently triggers prostaglandin E2 release as an inhibitory DAMP to counterpoise the adjuvanticity of immunostimulatory DAMPs. Pharmacological blockade of prostaglandin E2 biosythesis favors CD103+ dendritic cell activation that primes a Tc1-polarized CD8+ T cell response to bolster tumor rejection. Herein, we postulate that an intricate balance between immunostimulatory and inhibitory DAMPs could determine the outcome of drug-induced ICD and pose COX-2/prostaglandin E2 blockade as a strategy to harness ICD.

Delayed diagnosis of tuberculosis: risk factors and effect on mortality among older adults in Hong Kong

OBJECTIVE

To assess the risk factors and effects of delayed diagnosis on tuberculosis (TB) mortality in Hong Kong.

METHODS

All consecutive patients with TB notified in 2010 were tracked through their clinical records for treatment outcome until 2012. All TB cases notified or confirmed after death were identified for a mortality survey on the timing and causes of death.

RESULTS

Of 5092 TB cases notified, 1061 (20.9%) died within 2 years of notification; 211 (4.1%) patients died before notification, 683 (13.4%) died within the first year, and 167 (3.3%) died within the second year after notification. Among the 211 cases with TB notified after death, only 30 were certified to have died from TB. However, 52 (24.6%) died from unspecified pneumonia/sepsis possibly related to pulmonary TB. If these cases are counted, the total TB-related deaths increases from 191 to 243. In 82 (33.7%) of these, TB was notified after death. Over 60% of cases in which TB diagnosed after death involved patients aged ≥80 years and a similar proportion had an advance care directive against resuscitation or investigation. Independent factors for TB notified after death included female sex, living in an old age home, drug abuse, malignancy other than lung cancer, sputum TB smear negative, sputum TB culture positive, and chest X-ray not done.

CONCLUSIONS

High mortality was observed among patients with TB aged ≥80 years. Increased vigilance is warranted to avoid delayed diagnosis and reduce the transmission risk, especially among elderly patients with co-morbidities living in old age homes.

Palliative care: the need of the modern era

There is a great need for palliative care in the modern era of medicine. Despite medical advances, patients with life-limiting illnesses still suffer significantly. Palliative care emerged a half century ago as an ethos based on compassion and care for patients and their families to relieve their suffering. It entails a paradigm shift from the biomedical model to the biopsychospiritual model. Palliative care is recognised by the World Health Organization as an essential part of the continuum of universal health coverage. In 2014, the World Health Assembly approved a resolution on "Strengthening of palliative care as a component of comprehensive care throughout the life course". Despite Hong Kong's relatively good local palliative care service coverage for patients who died of cancer and end-stage renal failure, service gaps for palliative care do exist among our ageing population with non-malignant life-limiting illnesses. We strongly urge the Hong Kong Government to develop our local palliative care policy in response to the World Health Assembly's resolution. Growing international and local evidence demonstrates the impacts of palliative care on patient outcomes, caregivers, and health care. Such outcomes can be service-based, disease-based, or symptom/suffering-based. The goal of palliative care is to relieve health-related suffering. Evidence-based management of pain, breathlessness, and psychospiritual suffering are discussed. Care in the end-of-life phase should be an integral part of palliative care, promoting patient choice, advance care planning, and good death.

Spin-transfer torque generated in graphene based topological insulator heterostructures

We studied the spin-transfer torque (STT) in graphene based normal-metal/topological-insulator/ferromagnet heterostructures (N/TI/F), which is induced by the helical spin-polarized current in the quantum spin Hall insulator. We found that the STT is comparable in magnitude to the STT in ferromagnetic-normal- ferromagnetic graphene junction, while not requiring additional ferromagnetic layer with fixed magnetization, which makes it advantageous for the manipulation of magnetic devices in spintronics. More interestingly, the STT is very robust in our proposed nanostructure, as it is immune to changes in the geometry due to an asymmetrically notch or the presence of random nanopores in the quantum spin Hall insulator. Our theoretical prediction suggests that graphene based quantum spin Hall insulator could be used for very efficient magnetization manipulation for magnetic materials.

Creation of quasi-Dirac points in the Floquet band structure of bilayer graphene

We study the Floquet quasi-energy band structure of bilayer graphene when it is illuminated by two laser lights with frequencies [Formula: see text] and [Formula: see text] using Floquet theory. We focus on the dynamical gap formed by the conduction band with Floquet index  =  -1 and the valence band with Floquet index  =  +1 to understand how Dirac points can be formed. It is found that the dynamical gap does not have rotation symmetry in the momentum space, and quasi-Dirac points, where the conduction and valence bands almost touch, can be created when the dynamical gap closes along some directions with suitably chosen radiation parameters. We derive analytical expressions for the direction dependence of the dynamical gaps using Lowdin perturbation theory to gain a better understanding of the formation of quasi-Dirac points. When both radiations are circularly polarized, the gap can be exactly zero along some directions, when only the first and second order perturbations are considered. Higher order perturbations can open a very small gap in this case. When both radiations are linearly polarized, the gap can be exactly zero up to the fourth order perturbation and more than one quasi-Dirac point is formed. We also study the electron velocity around a dynamical gap and show that the magnitude of the velocity drops to values close to zero when the k vector is near to the gap minimum. The direction of the velocity also changes around the gap minimum, and when the gap is larger in value the change in the velocity direction is more gradual. The warping effect does not affect the formation of a Dirac point along the k _x axis, while it prevents its formation when there is phase shift between the two radiations.

Spin-polarized transport in graphene nanoribbons with Rashba spin-orbit interaction: the effects of spatial symmetry

We study the spin-dependent transport properties of graphene nanoribbons with Rashba spin-orbit interaction (SOI). It is found that highly spin polarized electrical currents can be produced in asymmetrically-notched graphene nanoribbons, and the polarization components are found to be along the x, y and z directions. The spin polarization is largely enhanced by breaking the spatial symmetries of ideal graphene nanoribbons with Rashba SOI, and the spin polarized electrical currents with higher flexibility in the orientation of the polarization can be generated. This offers new possibilities for the generation of high spin polarization in graphene nanoribbons without external magnetic fields.

The pattern of cervical smear abnormalities in marginalised women in Hong Kong

INTRODUCTION

"Ripple Action" and "WE Stand" are projects co-organised by the Hong Kong Women Doctors Association. The two projects organise free cervical screening for low-income women, new immigrants from Mainland China, and ethnic minority women. The objective of this study was to analyse the pattern of cervical smear abnormalities in these marginalised women.

METHODS

The study group consisted of 1189 marginalised women who participated in a free cervical screening campaign, including 324 low-income local Chinese, 540 new immigrants from Mainland China, and 325 ethnic minority women. The comparison group consisted of 1141 local Chinese who attended a well women clinic. The prevalence of cervical smear abnormalities was compared using Chi squared test.

RESULTS

In the study group, 42.6% of women had never had a cervical smear. Compared with the comparison group, they had a significantly higher prevalence of cervical smear abnormalities (13.7% vs 1.4%; P<0.001), including atypical smear (10.8% vs 0.5%; P<0.001), low-grade lesion (1.8% vs 0.8%; P=0.036), and high-grade lesion (1.1% vs 0.1%; P=0.002). Logistic regression analysis showed that the strongest predictors for abnormal cervical smear were being South Asian (odds ratio=11.859; 95% confidence interval, 4.635-30.341), South-East Asian (6.484; 3.192-13.171), or new immigrant from Mainland China (6.253; 2.463-15.877).

CONCLUSIONS

Marginalised women had a significantly higher prevalence of cervical smear abnormality than the general population and almost half had never had a cervical smear before. Outreach strategies are needed to enrol this population into screening programmes.

A valley and spin filter based on gapped graphene

We study highly valley- and spin-polarized current in single-layer gapped graphene without spin-orbit coupling. The structure considered is a three-barrier structure with one spin-splitting barrier and two electrical potential barriers with vector potentials. The electrons in the two valleys transmit differently because of the valley-dependent reflection between two adjacent barriers, while the spin-up and spin-down electrons transmit differently because of the spin splitting. The structure is different from other structures in which spin-orbit coupling plays an important role in the observation of valley- and spin-polarized current. We can control the spin and valley polarization by changing the width of the barrier or the strength of the spin splitting. The structure proposed in this paper can be used to make valley and spin devices.

Has Choosing Wisely® affected rates of dual-energy X-ray absorptiometry use?

Reducing overuse of tests such as dual-energy X-ray absorptiometry (DXA) scans in younger women is an important quality issue. We evaluated trends in DXA ordering before and after Choosing Wisely recommendations were released. We found no significant difference in ordering trends suggesting that other initiatives are needed to change behavior.

INTRODUCTION

Reducing overuse of tests such as dual-energy X-ray absorptiometry (DXA) scans in younger women is an important quality issue, but trends in care are difficult to change. We evaluated (1) trends in DXA ordering before and after the Choosing Wisely recommendation release and (2) patterns of key characteristics that indicate a potentially appropriate DXA scan order.

METHODS

We performed a retrospective longitudinal analysis of electronic health record data at a multi-specialty, ambulatory care network of 34 practices across Maryland and Washington, DC. Since the Choosing Wisely DXA recommendation was released April 2012, the study periods were April-December 2011 (pre-initiative) and April-December 2012 (post-initiative). Women between 50 and 64 years with primary care encounters, and primary care providers who saw ten or more women in the study population in both pre and post periods were included.

RESULTS

For 42,320 eligible patients, the mean provider ordering rate was 2.6 % pre-initiative and 2.0 % post-initiative; there was no significant difference in trend over time. Over 70 % of the population had no characteristics associated with potentially appropriate DXA ordering. Low body mass index, current smoker status, and osteopenia were the most common characteristics indicating potentially appropriate DXA orders. Patients with any of these three characteristics had DXA ordering rates between 3-20 %.

CONCLUSIONS

The trend in provider ordering rates of DXA scans did not decrease after the release of the DXA Choosing Wisely recommendation. Targeted initiatives addressing providers with high ordering rates will be needed to change behavior.

Nearly perfect valley filter in silicene

We demonstrate theoretically how a perfect valley filter can be obtained in silicene under the effects of a ferromagnetic stripe and an electric field perpendicular to silicene. A ferromagnetic stripe or an electric field alone can not generate any valley polarization in silicene, but a combination of them can make a perfect valley filter. Two configurations, one with magnetization of the ferromagnetic stripe being perpendicular to the silicene plane and one being parallel to the current direction, are considered. Our proposed device is useful for the realization of a valley beam filter in the development of valleytronic devices.

Sinogram Affirmed Iterative Reconstruction (SAFIRE) versus weighted filtered back projection (WFBP) effects on quantitative measure in the COPDGene 2 test object

PURPOSE

Assessing pulmonary emphysema using Quantitative CT of the lung depends on accurate measures of CT density. Sinogram-Affirmed-Iterative-Reconstruction (SAFIRE) is a new approach for reconstructing CT data acquired at significantly lower doses. However, quantitative effects of this method remain unexplored. The authors investigated the effects on the median values of materials in the COPDGene2 test-object as a function of the reconstruction method [weighted filtered back projection (WFBP) versus SAFIRE], test-object size, dose, and material composition using a Siemens SOMATOM Definition FLASH CT scanner.

METHODS

The COPDGene2 test-object contains eight materials; acrylic, water, four foams (20 lb, 12 lb, lung-equivalent, and 4 lb emphysema-equivalent), internal and external-air. The test-object was scanned with three different outer ring sizes, simulating three different body habitus. There is an average size (36 cm) Ring A, large size (40 cm) Ring B, and small size Ring C (30 cm). The CT protocol used 120 kVp, 0.5 s rotation, 1.0 pitch, and a 0.6 slice collimation with progressively decreasing x-ray exposure values, 11.94-0.74 mGy. With a thorax length of 30 cm, the corresponding effective doses would be 5.01-0.31 mSv. The effects of using SAFIRE versus WFBP were assessed using a two tailed t-test for each ring size, material, and dose. Multivariable linear regression was used to evaluate the relative effects of ring size, material composition, dose, and reconstruction method on the measured median value in HU.

RESULTS

SAFIRE versus WFBP, at the largest ring size and two lowest doses there was a significant difference in median values of 4 lb-foam, p<0.01. Using the smallest ring size at the lowest dose level there was a significant difference in the median value of 4 lb-foam, but the effect size was small, 1 HU. There is a significant difference in median values of both internal and external air using both the small and medium size rings at the three lowest dose levels, p<0.05. There are significant differences noted at both high and low dose levels when using the large ring size in the median values of internal and external air when, p<0.05. These effects on 4 lb-foam, inside and outside air are shown to be in part due to truncation effects on the median value since the lowest HU value in the CT scale used is -1024 HU. Multivariable linear regression results demonstrated significant effects on the measured material median value and standard deviation due to ring size, material composition, dose level, and reconstruction method, p<0.05.

CONCLUSIONS

The authors have shown that there is no significant effect on the median values obtained when using WFBP versus SAFIRE in materials with CT density between 120 and -856 HU using three different test-object sizes and CT doses that vary from 11.94 to 0.74 mGy. The authors have demonstrated there are significant effects on median values obtained when using WFBP versus SAFIRE in materials with CT density values between -937 and -1000 HU depending on the ring size and dose used. As expected, there is considerable reduction in image noise (lower standard deviation) using SAFIRE versus WFBP with all ring sizes, doses, and materials in the COPDGene2 test-object.

Effects of van der Waals interaction and electric field on the electronic structure of bilayer MoS2

The modification of the electronic structure of bilayer MoS2 by an external electric field can have potential applications in optoelectronics and valleytronics. Nevertheless, the underlying physical mechanism is not clearly understood, especially the effects of the van der Waals interaction. In this study, the spin orbit-coupled electronic structure of bilayer MoS2 has been investigated using the first-principle density functional theory. We find that the van der Waals interaction as well as the interlayer distance has significant effects on the band structure. When the interlayer distance of bilayer MoS2 increases from 0.614 nm to 0.71 nm, the indirect gap between the Γ and Λ points increases from 1.25 eV to 1.70 eV. Meanwhile, the energy gap of bilayer MoS2 transforms from an indirect one to a direct one. An external electric field can shift down (up) the energy bands of the bottom (top) MoS2 layer and also breaks the inversion symmetry of bilayer MoS2. As a result, the electric field can affect the band gaps, the spin-orbit interaction and splits the valance bands into two groups. The present study can help us understand more about the electronic structures of MoS2 materials for potential applications in electronics and optoelectronics.

Anomalous quantized conductance in a half-metal/topological superconductor/half-metal junction

The composite topological superconductor (TS), which is made of one-dimensional spin-orbit coupled nanowire with proximity-induced superconductivity from an s-wave superconductor, is not a pure p-wave superconductor, but has a suppressed s-wave pairing. We calculate the conductance spectrum of a half-metal/TS/half-metal junction in order to probe the pairing states and the spin texture of the p-wave pairing. It is found that, besides the regular quantized conductance peak contributed by Majorana fermions (MFs) when the half-metal magnetization is parallel to the MF spin, an anomalous quantized conductance peak exists when they are almost antiparallel. The physical origin is the MF-assisted local Andreev reflection to condense s-wave pairings. The anomalous quantized conductance is also confirmed by the Kitaev's p-wave model with a nonzero s-wave pairing. The findings might provide a new way to find the MF.

The effect of interlayer coupling on electron transport in graphene nanoribbons: a potential method for nanoposition sensing

We report a study on the effect of electron transport in a monolayer armchair graphene nanoribbon due to coupling to another monolayer armchair graphene ribbon, which is put on top of the first one. The conductance of the bottom ribbon oscillates when the top ribbon moves, and the oscillation can be used to determine stepwise position changes of the top ribbon for step sizes as small as 3.68 Å. The conductance oscillation arises from the rapid electron probability oscillations in the lowest three subbands of an armchair graphene ribbon. The phenomenon has potential applications in nanoposition sensing.

Adsorbate electric fields on a cryogenic atom chip

We investigate the behavior of electric fields originating from adsorbates deposited on a cryogenic atom chip as it is cooled from room temperature to cryogenic temperature. Using Rydberg electromagnetically induced transparency, we measure the field strength versus distance from a 1 mm square of yttrium barium copper oxide (YBCO) patterned onto a yttria stabilized zirconia chip substrate. We find a localized and stable dipole field at room temperature and attribute it to a saturated layer of chemically adsorbed rubidium atoms on the YBCO. As the chip is cooled towards 83 K we observe a change in sign of the electric field as well as a transition from a localized to a delocalized dipole density. We relate these changes to the onset of physisorption on the chip surface when the van der Waals attraction overcomes the thermal desorption mechanisms. Our findings suggest that through careful selection of substrate materials, it may be possible to reduce the electric fields caused by atomic adsorption on chips, opening up experiments to controlled Rydberg-surface coupling schemes.

Disorder effect on the integer quantum Hall effect in trilayer graphene

We numerically investigate the disorder effect on the integer quantum Hall effect in a trilayer graphene (TLG) system by use of the Kubo formula. For a clean sample, both Bernal (ABA) and rhombohedral (ABC) stacked TLGs display the same quantum rule with abnormal quantized Hall plateaus σxy = νe(2)/h (ν =± 6, ± 10, ± 14,…) in the band center and normal quantized Hall plateaus at the band edges. In the presence of disorder, the Hall plateaus become obscure and the higher plateaus disappear first with the increase of the disorder; however, the Hall plateaus of the ABA-stacked TLG are destroyed more readily in comparison with the ABC-stacked one. The longitudinal conductance minimums of the system corresponding to the Hall plateaus become narrower and thinner with disorder, and those of the ABC-stacked TLG are comparatively more stable than those of the ABA structure. The findings indicate that the l = 3 chiral quasiparticles with cubic energy dispersion in ABC-stacked TLG have comparatively stronger immunity to the disorder than the l = 1 and 2 chiral quasiparticles in the ABA counterpart.

Surface roughness induced electron mobility degradation in InAs nanowires

In this work, we present a study of the surface roughness dependent electron mobility in InAs nanowires grown by the nickel-catalyzed chemical vapor deposition method. These nanowires have good crystallinity, well-controlled surface morphology without any surface coating or tapering and an excellent peak field-effect mobility up to 15,000 cm(2) V(-1) s(-1) when configured into back-gated field-effect nanowire transistors. Detailed electrical characterizations reveal that the electron mobility degrades monotonically with increasing surface roughness and diameter scaling, while low-temperature measurements further decouple the effects of surface/interface traps and phonon scattering, highlighting the dominant impact of surface roughness scattering on the electron mobility for miniaturized and surface disordered nanowires. All these factors suggest that careful consideration of nanowire geometries and surface condition is required for designing devices with optimal performance.

Reference standard and statistical model for intersite and temporal comparisons of CT attenuation in a multicenter quantitative lung study

PURPOSE

The purpose of this study was to detect and analyze anomalies between a large number of computed tomography (CT) scanners, tracked over time, utilized to collect human pulmonary CT data for a national multicenter study: chronic obstructive pulmonary disease genetic epidemiology study (COPDGene).

METHODS

A custom designed CT reference standard "Test Object" has been developed to evaluate the relevant differences in CT attenuation between CT scanners in COPDGene. The materials used in the Test Object to assess CT scanner accuracy and precision included lung equivalent foam (-856 HU), internal air (-1000 HU), water (0 HU), and acrylic (120 HU). Nineteen examples of the Test Object were manufactured. Initially, all Test Objects were scanned on the same CT scanner before the Test Objects were sent to the 20 specific sites and 42 individual CT scanners that were used in the study. The Test Objects were scanned over 17 months while the COPDGene study continued to recruit subjects. A mixed linear effect statistical analysis of the CT scans on the 19 Test Objects was performed. The statistical model reflected influence of reconstruction kernels, tube current, individual Test Objects, CT scanner models, and temporal consistency on CT attenuation.

RESULTS

Depending on the Test Object material, there were significant differences between reconstruction kernels, tube current, individual Test Objects, CT scanner models, and temporal consistency. The two Test Object materials of most interest were lung equivalent foam and internal air. With lung equivalent foam, there were significant (p < 0.05) differences between the Siemens B31 (-856.6, ±0.82; mean ± SE) and the GE Standard (-856.6 ± 0.83) reconstruction kernel relative to the Siemens B35 reference standard (-852.5 ± 1.4). Comparing lung equivalent foam attenuation there were also significant differences between CT scanner models (p < 0.01), tube current (p < 0.005), and in temporal consistency (p < 0.005) at individual sites. However, there were no significant effects measurable using different examples of the Test Objects at the various sites compared to the reference scans of the 19 Test Objects. For internal air, significant (p < 0.005) differences were found between all reconstruction kernels (Siemens B31, GE Standard, and Phillips B) compared to the reference standard. There were significant differences between CT models (p < 0.005), and tube current (p < 0.005). There were no significant effects measurable using different examples of the Test Objects at the various sites compared to the reference scans of the 19 Test Objects. Differences, across scanners, between external air and internal air measures in this simple (relative to the in vivo lung) test object varied by as much as 15 HU.

CONCLUSIONS

The authors conclude that the Test Object designed for this study was able to detect significant effects regarding individual CT scanners that altered the CT attenuation measurements relevant to the study that are used to determine lung density. Through an understanding of individual scanners, the Test Object analysis can be used to detect anomalies in an individual CT scanner and to statistically model out scanner differences and individual scanner changes over time in a large multicenter trial.

A bipolar spin-filtering effect in graphene zigzag nanoribbons with spin-orbit coupling

We predict a large spin-filtering effect in graphene zigzag nanoribbons in the presence of Rashba spin-orbit coupling. The spin polarization of the transmitted current reaches a maximum when the incoming electrons occupy only one subband and the outgoing electrons occupy two subbands (spin is not taken into account). This situation can be reached by applying a potential barrier or a width constriction to the incoming lead of the ribbon. A simple physical picture is provided to explain the spin-filtering effect. Because of the electron-hole symmetry and the time-reversal symmetry, the spin-filtering is antisymmetric for the hole when compared with that for the electron. So the bipolar spin-polarized current can be generated by tuning the Fermi energy across the Dirac point. Besides, the wedge-shaped constriction can modify the conductance spin polarization.

Pure spin current generation in monolayer graphene by quantum pumping

We study a method to generate pure spin current in monolayer graphene over a wide range of Fermi energy by adiabatic quantum pumping. The device consists of three gate electrodes and two ferromagnetic strips, which induce a spin-splitting in the graphene through the proximity effect. A pure spin current is generated by applying two periodic oscillating gate voltages. We find that the pumped pure spin current is a sensitive oscillatory function of the Fermi energy. Large spin currents can be found at Fermi energies where there are Fabry-Perot resonances in the barriers. Furthermore, we analyze the effects of the parameters of the system on the pumped currents. Our predicted pumped spin current can be of the order of 100 nA which is measurable using the current technology. The proposed method is useful in the realization of graphene spintronic devices.

The dynamical conductance of graphene tunnelling structures

The dynamical conductances of graphene tunnelling structures were numerically calculated using the scattering matrix method with the interaction effect included in a phenomenological approach. The overall single-barrier dynamical conductance is capacitative. Transmission resonances in the single-barrier structure lead to dips in the capacitative imaginary part of the response. This is different from the ac responses of typical semiconductor nanostructures, where transmission resonances usually lead to inductive peaks. The features of the dips depend on the Fermi energy. When the Fermi energy is below half of the barrier height, the dips are sharper. When the Fermi energy is higher than half of the barrier height, the dips are broader. Inductive behaviours can be observed in a double-barrier structure due to the resonances formed by reflection between the two barriers.

Transverse spin current in the s-wave/p-wave Josephson junction

We report a theoretical study on spin transport in the hybrid Josephson junction composed of singlet s-wave and triplet p-wave superconductor. The node of the triplet pair potential is considered perpendicular to the interface of the junction. Based on a symmetry analysis, we predict that there is no net spin density at the interface of the junction but instead a transverse mode-resolved spin density can exist and a nonzero spin current can flow transversely along the interface of the junction. The predictions are numerically demonstrated by means of the lattice Matsubara Green's function method. It is also shown that, when a normal metal is sandwiched in between two superconductors, both spin current and transverse mode-resolved spin density are only residing at two interfaces due to the smearing effect of the multimode transport. Our findings are useful for identifying the pairing symmetry of the p-wave superconductor and generating spin current.

Spin-polarized quantum pumping in bilayer graphene

We study adiabatic quantum pumping in bilayer graphene where two-barrier potentials are weakly modulated as pumping parameters. Comparing the results with those for a normal quantum pump of non-chiral quasiparticles, we find that the chirality of quasiparticles in bilayer graphene heavily affects the pumped current through chiral tunnelling. When an exchange splitting induced by the proximity of a ferromagnetic insulator is introduced, the pumped current becomes spin-polarized. It is interesting that an almost 100% polarized charge current and a pure spin current with vanishing charge current can all be achieved under suitable conditions. The experimental feasibility and the interlayer asymmetric effect in bilayer graphene caused by the gate and the ferromagnet structures are also discussed. The results are useful for spintronics applications based on graphene.

Spin accumulation in triplet Josephson junction

We employ a Hamiltonian method to study the equal-spin pairing triplet Josephson junction with different orbital symmetries of pair potentials. Both the spin/charge supercurrent and possible spin accumulation at the interface of the junction are analyzed by means of the Keldysh Green's function. It is found that a spontaneous angle-resolved spin accumulation can form at the junction's interface when the orbital symmetries of Cooper pairs in two triplet superconductors are different, the physical origin is the combined effect of the different orbital symmetries and different spin states of Cooper pairs due to the misalignment of two d vectors in triplet leads. An abrupt current reversal effect induced by misalignment of d vectors is observed and can survive in a strong interface barrier scattering because the zero-energy state appears at the interface of the junction. These properties of the p-wave Josephson junction may be helpful for identifying the order parameter symmetry.

Spin current pumped by a rotating magnetic field in zigzag graphene nanoribbons

We study electron spin resonance in zigzag graphene nanoribbons by applying a rotating magnetic field on the system without any bias. By using the nonequilibrium Green's function technique, the spin-resolved pumped current is explicitly derived in a rotating reference frame. The pumped spin current density increases with the system size and the intensity of the transverse rotating magnetic field. For graphene nanoribbons with an even number of zigzag chains, there is a nonzero pumped charge current in addition to the pumped spin current owing to the broken spatial inversion symmetry of the system, but its magnitude is much smaller than the spin current. The short-ranged static disorder from either impurities or defects in the ribbon can depress the spin current greatly due to the localization effect, whereas the long-ranged disorder from charge impurities can avoid inter-valley scattering so that the spin current can survive in the strong disorder for the single-energy mode.

Spin reversal effect in hybrid s(±)-wave/p-wave Josephson junction

We report a theoretical study on a hybrid Josephson junction consisting of a proposed s( ± )-wave ferropnictide superconductor and a p-wave superconductor. It is found that the relative π phase shift intrinsic to the s( ± )-wave pairing can lead to an accumulated spin reversal effect at the junction interface and that the critical current has a vanishing point with the variation of the ratio of the interface resistances for each band. The spin reversal effect also appears with an increase of temperature and meanwhile the critical current exhibits a reentrant behavior. These findings can not appear for a usual s-wave state, so that they can be used to discriminate the s( ± )-wave pairing in superconducting ferropnictides from the conventional s-wave symmetry.

Triplet Josephson current modulated by Rashba spin-orbit coupling

We study the Rashba spin-orbit coupling (RSOC) effect on the supercurrent in a clean triplet superconductor/two-dimensional electron gas/triplet superconductor (TS/2DEG/TS) junction, where RSOC is considered in the 2DEG region. Based on the Bogoliubov-de Gennes equation and quantum scattering method, we show that RSOC can lead to a 0-π oscillation of supercurrent and the abrupt current reversal effect. The current direction can be reversed by a tiny modulation of RSOC, and this is attributed to the equal spin pairing of the TS order parameter and the spin precession phase of the quasiparticle traveling in the RSOC region. The RSOC strength can be controlled by an electric field in experiments, thus our findings provide a purely electric means to modulate the supercurrent in TS Josephson junctions.

Spin-polarized transport induced by spin-pumping in a Rashba ring

The Keldysh Green's function method is employed to study spin-dependent electron transport through a Rashba ring with a quantum dot (QD) embedded in one of its arms. Zero charge bias is applied on the system while a rotating magnetic field is considered in the QD to pump pure spin current. The Rashba spin-orbital coupling (RSOC) can cause a spin precession phase of the electron passing through the ring, so that the quantum interference in the ring can lead to a spin-polarized charge current flowing in the leads and the arm without a QD, whereas only pure spin current is flowing in the other arm with a QD. It is shown that for low frequency ω of the rotating magnetic field, the pumped charge current is proportional to ω unlike the charge current produced by mono-parametric quantum charge pumping, which is usually proportional to ω(2). Moreover, the magnitude, the direction, as well as the spin-polarization of the charge current can be controlled by tuning the device parameters such as the QD energy level, the RSOC strength, and the strength of the electron tunneling between the leads and the QD. Hence the studied device may serve as a generating source for tunable spin-polarized current in the spintronics field.

Single-parameter charge pump in a zigzag graphene nanoribbon

We report a theoretical study of a single-parameter quantum charge pump in the clean zigzag graphene nanoribbon (ZGNR) system. By Keldysh Green's function method, we show that a pumped current in the ZGNR with an even number of zigzag chains can sharply increase from zero as the frequency matches the Fermi energy, whereas the pumped charge current is always absent in the ZGNR with an odd number of zigzag chains as well as the GNR with armchair edges, it is attributed to the peculiar zero-energy edge state in the ZGNR and the symmetry breaking of the topologically inequivalent carbon atoms due to the zigzag edges. The pumped current in the even-ZGNR decreases with the Fermi energy and its direction is determined by Fermi energy below or above the Dirac point as well as the type of carbon atoms at one edge of the ZGNR. The two-parameter charge pump in the ZGNR is also discussed and the magnitude of the pumped current is comparable to the single-parameter pump when the pumping frequency matches the Fermi energy.

Josephson current oscillation in a Rashba ring

We propose to use Rashba spin-orbital coupling (RSOC) to modulate the Josephson current in a one-dimensional ring-SQUID (superconducting quantum interference device) without any magnetic field or magnetic material. Supercurrent oscillation due to spin-dependent quantum interference of spin wavefunctions passing through the two arms of the ring in the presence of RSOC is found. A pure spin current flows in the system's ground state without a supercurrent due to the combined effect of the RSOC precession phase and the electron traveling phase caused by the asymmetry in the two arms of the ring. This purely electrical means of modulating the supercurrent by varying the RSOC will be useful for designing novel superconductor devices.

Spin density induced by equilibrium spin current in a magnetic field

We propose theoretically to use an external magnetic field to detect the equilibrium spin current which flows in a narrow strip. The spin current is generated by two noncollinear ferromagnets attached to the strip and the applied magnetic field is perpendicular to the plane of the strip. It is demonstrated by using the Keldysh Green's function that the interaction between the spin current and the magnetic field causes an antisymmetrical spin density at the two lateral edges of the strip. The spin density can be directly measured experimentally. Its magnitude and direction can be readily controlled by the magnetizations of the ferromagnets. The proposed scheme offers a new approach to the detection of the pure spin current.

An empirical study of characteristics and types of homicide-suicides in Hong Kong, 1989-2005

BACKGROUND

Clinical classification of types of homicide-suicide (HS) was proposed, but no information on empirical-based classification and prevalence of different types of HS was available. This paper aimed to empirically classify HS events into different clusters and to discuss specific evidence-based prevention initiatives.

METHOD

Data of HS offenders from Coroner's Court were analyzed through a two-step cluster analysis. Number of clusters and appropriate allocations of cases were obtained. External background variables were tested through post hoc tests to explore the differences among clusters.

RESULTS

Two hundred and thirty-one people died in 98 episodes in the study period (1989-2005). The majority of HS offenders were male (n=68, 68.7%) and aged 30-49 (n=62, 62.6%). Domestic killing was the major type of HS in which over 60% of the homicide motivation was related to spousal conflicts or altruistic reasons. Spouses (n=46, 46.5%) and children (n=47, 47.5%) were predominantly the victims. The common killing methods included chopping with weapons (n=33, 33.3%) and charcoal burning (n=22, 22.2%). Six clusters of HS were derived from the cluster analysis and were further reduced to four major classes. Four major classes were dispute, conflicts in a relationship, altruistic, and mental illness. These classes could be differentiated by methods of homicide and suicide, gender of perpetrator, relationship with victim, and indebtedness.

CONCLUSIONS

Financial problem, dispute and domestic violence are significant precipitants of HS in Hong Kong. Those people associated with the precipitating factors should be the targets for intervention and prevention.

Follicular dendritic cell sarcoma of inguinal lymph node--a case report

Follicular dendritic cell sarcomas (FDCS) are rare neoplasms that involve lymph nodes or extranodal sites. They show varied histological features and thus can be mistaken for carcinoma or sarcoma. Correct identification is important for further management. A 43-year-old Indian female presented with a three-month history of progressive swelling at the right inguinal region. It was excised completely and was reported as lymph node with metastatic poorly differentiated carcinoma based on Haematoxylin and eosin (H&E) stain findings. Computerized tomography (CT) scans of thorax, abdomen and pelvis were normal and did not reveal a primary site. Following this, the case was referred to one of the authors. The slides were reviewed and a variety of immunocytochemical markers were done. The tumour cells were negative for epithelial, melanocytic, neural, leucocyte and soft tissue tumour markers. They were immunopositive for CD21, CD35 and negative for CD68. Based on the immunocytochemical findings, a final diagnosis of FDCS was made. This case highlights the histological and immunophenotypical profile of a rare tumour which requires a high index of suspicion for diagnosis.

Conductance oscillations in a nanowire double junction

The interaction between two nanowire cross-junctions is studied in a three-wire double-junction structure. The dc conductances between terminals in the double-junction structure are calculated from the Green's function, which is obtained using the modular Green's function approach. Significant oscillations are found in the inter-wire conductances in both junctions, which are the consequence of interference of electron waves reflected between junctions. A phenomenological expression, which can relate the positions of neighboring oscillation peaks, is developed based on the interference mechanism. The interaction between quasi-bound states formed at the junctions is found to be negligible and has no significant effect on the inter-wire conductance peaks. Our results show that interaction between neighboring junctions should be properly considered in the modeling and design of nanowire devices and circuits.

Real time mass flow rate measurement using multiple fan beam optical tomography

This paper presents the implementing multiple fan beam projection technique using optical fibre sensors for a tomography system. From the dynamic experiment of solid/gas flow using plastic beads in a gravity flow rig, the designed optical fibre sensors are reliable in measuring the mass flow rate below 40% of flow. Another important matter that has been discussed is the image processing rate or IPR. Generally, the applied image reconstruction algorithms, the construction of the sensor and also the designed software are considered to be reliable and suitable to perform real-time image reconstruction and mass flow rate measurements.

Forced expression of a constitutively active form of Stat3 in mouse epidermis enhances malignant progression of skin tumors induced by two-stage carcinogenesis

Recently, our laboratory demonstrated that Stat3 is required for the de novo development of chemically-induced skin tumors. We have further investigated the role of Stat3 in epithelial carcinogenesis using mice in which the expression of a constitutively active/dimerized form of Stat3 (Stat3C) is targeted to the proliferative compartment of epidermis (referred to as K5.Stat3C transgenic mice). Keratinocytes from K5.Stat3C mice showed increased survival following exposure to 7,12-dimethylbenz[a]anthracene (DMBA) and enhanced proliferation following exposure to 12-O-tetradecanoylphorbol-13-acetate (TPA). In two-stage chemical carcinogenesis experiments using DMBA as the tumor initiator and TPA as the promoter, K5.Stat3C mice developed skin tumors with a shorter latency and in much greater number compared to non-transgenic littermates. Remarkably, 100% of the skin tumors that developed in K5.Stat3C transgenic mice bypassed the premalignant stage and were initially diagnosed as carcinoma in situ which rapidly progressed to squamous cell carcinoma (SCC). These tumors were highly vascularized, poorly differentiated and invasive and loss of expression of K10, filaggrin and E-cadherin was observed by 20 weeks. Finally, overexpression of Stat3C in a papilloma cell line led to enhanced cell migration and enhanced invasion through Matrigel in both the absence and presence of growth factors. In addition to its critical role in early stages of epithelial carcinogenesis, the current study reveals a novel role for Stat3 in driving malignant progression of skin tumors in vivo.

The impact of palliative care on cancer deaths in Hong Kong: a retrospective study of 494 cancer deaths

OBJECTIVES

To study the utilization of public health care by advanced cancer patients in their last 6 months of life and their end-of-life process within the last 2 weeks of life.

METHODS

This was a retrospective study on 494 cancer deaths from four public hospitals in 2005. This sample was selected from all in-patient cancer deaths by the ratio of one in four. Data were collected by review of charts and an electronic data base.

RESULTS

A total of 494 cancer deaths were analysed. The mean age of all cancer patients (n = 494) was 72.6 years. Two-thirds of cancer patients received palliative care and half died in palliative care setting. Patients were categorized into three groups according to palliative care coverage and the place of death. The first group comprised of patients who received palliative care service and died in palliative care units (PCS-PCD group, n = 247); the second group of patients who received palliative care service within the last 6 months of life but died in non-palliative care wards (n = 86); and the third group of patients who never received palliative care and who died in non-palliative care wards (NPCS-NPCD group, n = 161). Differences among groups were tested by one way ANOVA. During the last 6 months of life, patients in the PCS-PCD group had less admission to acute care wards (P = 0.012), shorter duration of stay in acute care wards (P = 0.003), and less admission to an intensive care unit setting (P < 0.001). Within the last 2 weeks of life, the PCS-PCD group had fewer interventions initiated (P < 0.001); had higher number of symptoms documented in patient's record (P < 0.001); and were more likely to receive analgesics (P < 0.001), adjuvant analgesics (P < 0.001) and sedatives (P < 0.001). Patients in PCS-PCD group were more physically dependent in the last 2 weeks of life (P < 0.001), but mentally more alert at 72 hours before death (P < 0.001). Patients in the NPCS-NPCD group had fewer patients with a do not resuscitate order present (P < 0.001), and more patients with cardiopulmonary resuscitation performed (P < 0.001).

CONCLUSION

Our results suggest that palliative care service has played a role in improving end-of-life cancer care in Hong Kong.

Determinants of chronic obstructive pulmonary disease in Chinese patients in Hong Kong

BACKGROUND

The prevalence of chronic obstructive pulmonary disease (COPD) is rising in many parts of the world. This is a study of risk factors for COPD in Chinese patients in Hong Kong.

DESIGN

Case-control study matched by sex and age (+/-5 years).

METHODS

A total of 289 consecutive patients with COPD were recruited from out-patient clinics while healthy controls were recruited from two sources: random population and community centres for senior citizens. All patients and controls underwent a questionnaire-based interview and spirometry.

RESULTS

The mean ages of COPD patients and controls were 71.1 +/- 9.4 and 67.5 +/- 9.3 years, respectively. The male to female ratio of COPD patients was 5 to 1. Smoking was found to be the most important determinant for COPD, followed by poor education and low body mass index adjusted for confounders. A dose-dependent relationship was found between the risk of COPD and pack-years smoked. Place of birth, exposure to environmental tobacco smoke and a history of asthma and tuberculosis were not associated with increased risk of COPD.

CONCLUSION

Despite a progressive reduction in prevalence, smoking remains the most important predictor of COPD in Hong Kong. Greater anti-smoking efforts are warranted.

Application of two-dimensional spectral surface plasmon resonance to imaging of pressure distribution in elastohydrodynamic lubricant films

What we believe to be a novel two-dimensional spectral surface plasmon resonance imaging technique determining pressure distribution in elastohydrodynamic lubricant films is presented. This technique makes use of the spectral characteristics associated with the surface plasmon resonance (SPR) effect, and it provides more spectral information in refractive index mapping than conventional contrast SPR imaging. Two-dimensional imaging is demonstrated and applied to a highly pressurized liquid lubricant trapped inside an elastohydrodynamic lubrication (EHL) dimple. The hydrostatic pressure inside the EHL dimple causes a localized change of the refractive index of the lubrication oil. This also results in a shift in the spectral SPR absorption dip. By monitoring the color changes within the SPR image and calibrating with lubricants of known refractive index profiles, we can obtain a direct measurement of the refractive index distribution within the EHL dimple. PB 2400 lubricant dimples were studied in our experiments. The proposed SPR imaging approach is irrespective of the absolute lubricant film thickness h, therefore overcoming the major limitations of a conventional optical interference technique. With further development of the two-dimensional refractive index mapping technique, widespread applications in various fields are possible, including high-throughput sensors and the detection of bioaffinity interactions.

Reliability, Validity, and Responsiveness of a 2-Min Walk Test To Assess Exercise Capacity of COPD Patients

PURPOSES

To investigate the reliability, validity, and responsiveness of a 2-min walk test (2MWT) in Chinese COPD patients with moderate-to-severe disease.

METHODS

This study consisted of two parts. Forty-seven stable COPD patients with moderate-to-severe disease participated in the first part of study for the investigation of reliability and validity. The demographic and anthropomorphic data collected included age, gender, body weight, height, and body mass index. Each subject performed a pulmonary function test, a cardiopulmonary exercise test, three trials of a 2MWT, and two trials of 6-min-walk test (6MWT) in random order within a 5-day period. Fifteen of these subjects participated in the second part of study for the evaluation of the responsiveness of the 2MWT following pulmonary rehabilitation. The 2MWT and 6MWT were conducted before and after the program for comparison.

RESULTS

Forty-five subjects (mean [+/- SD] age, 71.8 +/- 8.3 years; mean FEV1, 0.88 +/- 0.27 L) completed the first part of study, and 9 subjects (mean age, 74 +/- 8.7 years; mean FEV1, 0.94 +/- 0.28 L) completed the second part of study. The intraclass correlation coefficient of the repeated 2MWTs was high (R = 0.9994; p < 0.05), mean differences across trials ranged from 0.3 to 0.8 m (95% confidence interval, -3.1 to 4.6 m) demonstrated its high test-retest reliability. Significant correlations were found between the 2MWT and the 6MWT, the maximum oxygen uptake (V(O2)max) in milliliters per minute, and the V(O2)max in milliliters per kilogram per minute (r = 0.937, 0.454, and 0.555 respectively; p < 0.0125). Following rehabilitation, there were significant improvements in the mean 2MWT and 6MWT walking distance of 17.2 +/- 13.8 m and 60.6 +/- 35.5 m, respectively, with moderate effect sizes (0.61 and 0.53, respectively) and large standardized mean responses (1.25 and 1.70, respectively). High correlation was found between changes in the 2MWT and the 6MWT (r = 0.70; p < 0.05).

CONCLUSION

The 2MWT was shown to be a reliable and valid test for the assessment of exercise capacity and responsive following rehabilitation in patients with moderate-to-severe COPD. It is practical, simple, and well-tolerated by patients with severe COPD symptoms.

Computed tomography features of spontaneously perforated pyometra: a case report

Spontaneous perforation of pyometra is an extremely rare emergent gynecologic disease. We report a 73-year-old woman with a spontaneously perforated pyometra presenting with acute abdomen in the emergency department. A dedicated computed tomography examination of the abdominal and pelvic regions revealed the diagnosis. The patient recovered well after surgical intervention and antibiotic treatment.

[Matrix metalloproteinases and their inhibitors in lung cancer with malignant pleural effusion]

Matrix metalloproteinases (MMP) and tissue inhibitors of metalloproteinases (TIMP) play a crucial role in physiological and pathological matrix turnover. This study aimed to determine the occurrence of MMP and TIMP in lung cancer patients with malignant pleural effusions (CA).

METHODS

MMP-1, MMP-2, MMP-3, MMP-8, MMP-9, TIMP-1, and IMP-2 oncentrations were determined by ELISA and zymography in pleural effusions and plasma of 31 CA and 14 congestive heart failure (CHF) patients and in plasma of 18 healthy controls (CON).

RESULTS

MMP-2, TIMP-1, and TIMP-2 ELISA-concentrations were increased in CA pleural fluid vs. CA plasma (p < 0.005, p < 0.005, p < 0.05), in contrast to MMP-9 being higher in plasma (p < 0.005). Pleural fluid MMP-1 and MMP-8 were increased in CA vs. CHF (p < 0.05, p < 0.005). MMP and TIMP plasma concentrations were not different in CA vs. CHF, but MMP-9, TIMP-1, and TIMP-2 were increased vs. CON (p < 0.005, each). Gelatine zymography MMP-9/MMP-2 ratios were increased in CA plasma vs. effusion fluid (p < 0.005), in CA vs. CHF plasma, CA vs. CHF effusions (p < 0.005 each), and in CA vs. CON plasma (p < 0.05).

CONCLUSIONS

MMP-2, TIMP-1, and TIMP-2 accumulate in the pleural compartment in CA and CHF, probably reflecting an unspecific pleural reaction. MMP-1 and MMP-8 are increased in cellular rich CA pleural effusions only. The determination of MMP-9/MMP-2 ratios in pleural fluid may contribute to differentiate CHF from CA effusions.