Targeted care navigation to reduce hospital readmissions in 'at-risk' patients

BACKGROUND

Care navigation is commonly used to reduce preventable hospitalisation. The use of Electronic Health Record-derived algorithms may enable better targeting of this intervention for greater impact.

AIMS

To evaluate if community-based Targeted Care Navigation, supported by an Electronic Health Record-derived readmission risk algorithm, is associated with reduced rehospitalisation.

METHODS

A propensity score matching cohort (5 comparison to 1 intervention cohort ratio) study was conducted in an 850-bed Victorian public metropolitan health service, Australia, from May to November 2017. Admitted acute care patients with a non-surgical condition, identified as at-risk of hospital readmission using an Electronic Health Record-derived readmission risk algorithm provide by the state health department, were eligible. Targeted Care Navigation involved telephone follow-up support provided for 30 days post-discharge by a registered nurse. The hazard ratio for hospital readmission was calculated at 30, 60 and 90 days post-discharge using multivariable Cox Proportional Hazards regression.

RESULTS

Sixty-five recipients received care navigation and were matched to 262 people who did not receive care navigation. Excellent matching was achieved with standardised differences between groups being <0.1 for all 11 variables included in the propensity score, including the readmission risk score. The Targeted Care Navigation group had a significantly reduced hazard of readmission at 30 days (hazard ratio 0.34; 95% confidence interval: 0.12, 0.94) compared with the comparison group. The effect size was reduced at 60 and 90 days post-discharge.

CONCLUSION

We provide preliminary evidence that Targeted Care Navigation supported by an Electronic Health Record-derived readmission risk algorithm may reduce 30-day hospital readmissions.

Final Study Report of Andexanet Alfa for Major Bleeding With Factor Xa Inhibitors

BACKGROUND

Andexanet alfa is a modified recombinant inactive factor Xa (FXa) designed to reverse FXa inhibitors. ANNEXA-4 (Andexanet Alfa, a Novel Antidote to the Anticoagulation Effects of Factor Xa Inhibitors) was a multicenter, prospective, phase-3b/4, single-group cohort study that evaluated andexanet alfa in patients with acute major bleeding. The results of the final analyses are presented.

METHODS

Patients with acute major bleeding within 18 hours of FXa inhibitor administration were enrolled. Co-primary end points were anti-FXa activity change from baseline during andexanet alfa treatment and excellent or good hemostatic efficacy, defined by a scale used in previous reversal studies, at 12 hours. The efficacy population included patients with baseline anti-FXa activity levels above predefined thresholds (≥75 ng/mL for apixaban and rivaroxaban, ≥40 ng/mL for edoxaban, and ≥0.25 IU/mL for enoxaparin; reported in the same units used for calibrators) who were adjudicated as meeting major bleeding criteria (modified International Society of Thrombosis and Haemostasis definition). The safety population included all patients. Major bleeding criteria, hemostatic efficacy, thrombotic events (stratified by occurring before or after restart of either prophylactic [ie, a lower dose, for prevention rather than treatment] or full-dose oral anticoagulation), and deaths were assessed by an independent adjudication committee. Median endogenous thrombin potential at baseline and across the follow-up period was a secondary outcome.

RESULTS

There were 479 patients enrolled (mean age, 78 years; 54% male, 86% White; 81% anticoagulated for atrial fibrillation at a median time of 11.4 hours since last dose, with 245 (51%) on apixaban, 176 (37%) on rivaroxaban, 36 (8%) on edoxaban, and 22 (5%) on enoxaparin. Bleeding was predominantly intracranial (n=331 [69%]) or gastrointestinal (n=109 [23%]). In evaluable apixaban patients (n=172), median anti-FXa activity decreased from 146.9 ng/mL to 10.0 ng/mL (reduction, 93% [95% CI, 94-93]); in rivaroxaban patients (n=132), it decreased from 214.6 ng/mL to 10.8 ng/mL (94% [95% CI, 95-93]); in edoxaban patients (n=28), it decreased from 121.1 ng/mL to 24.4 ng/mL (71% [95% CI, 82-65); and in enoxaparin patients (n=17), it decreased from 0.48 IU/mL to 0.11 IU/mL (75% [95% CI, 79-67]). Excellent or good hemostasis occurred in 274 of 342 evaluable patients (80% [95% CI, 75-84]). In the safety population, thrombotic events occurred in 50 patients (10%); in 16 patients, this occurred during treatment with prophylactic anticoagulation that began after the bleeding event. No thrombotic episodes occurred after oral anticoagulation restart. Specific to certain populations, reduction of anti-FXa activity from baseline to nadir significantly predicted hemostatic efficacy in patients with intracranial hemorrhage (area under the receiver operating characteristic curve, 0.62 [95% CI, 0.54-0.70]) and correlated with lower mortality in patients <75 years of age (adjusted P=0.022; unadjusted P=0.003). Median endogenous thrombin potential was within the normal range by the end of andexanet alfa bolus through 24 hours for all FXa inhibitors.

CONCLUSIONS

In patients with major bleeding associated with the use of FXa inhibitors, treatment with andexanet alfa reduced anti-FXa activity and was associated with good or excellent hemostatic efficacy in 80% of patients.

REGISTRATION

URL: https://www.

CLINICALTRIALS

gov; Unique identifier: NCT02329327.

Impact of COVID-19 lockdowns on hospital presentations and admissions in the context of low community transmission: evidence from time series analysis in Melbourne, Australia

BACKGROUND

Melbourne, Australia, successfully halted exponential transmission of COVID-19 via two strict lockdowns during 2020. The impact of such restrictions on healthcare-seeking behaviour is not comprehensively understood, but is of global importance. We explore the impact of the COVID-19 pandemic on acute, subacute and emergency department (ED) presentations/admissions within a tertiary, metropolitan health service in Melbourne, Australia, over two waves of community transmission (1 March to 20 September 2020).

METHODS

We used 4 years of historical data and novel forecasting methods to predict counterfactual hospital activity for 2020, assuming absence of COVID-19. Observed activity was compared with forecasts overall, by age, triage category and for myocardial infarction and stroke. Data were analysed for all patients residing in the health service catchment area presenting between 4 January 2016 and 20 September 2020.

RESULTS

ED presentations (n=401 805), acute admissions (n=371 723) and subacute admissions (n=15 676) were analysed. Substantial departures from forecasted presentation levels were observed during both waves in the ED and acute settings, and during the second wave in subacute. Reductions were most marked among those aged >80 and <18 years. Presentations persisted at expected levels for urgent conditions, and ED triage categories 1 and 5, with clear reductions in categories 2-4.

CONCLUSIONS

Our analyses suggest citizens were willing and able to present with life-threatening conditions during Melbourne's lockdowns, and that switching to telemedicine did not cause widespread spill-over from primary care into ED. During a pandemic, lockdowns may not inhibit appropriate hospital attendance where rates of infectious disease are low.

[Update on collaborative autopsy-based research in German pathology, neuropathology, and forensic medicine]

BACKGROUND

Autopsies are a valuable tool for understanding disease, including COVID-19.

MATERIALS AND METHODS

The German Registry of COVID-19 Autopsies (DeRegCOVID), established in April 2020, serves as the electronic backbone of the National Autopsy Network (NATON), launched in early 2022 following DEFEAT PANDEMIcs.

RESULTS

The NATON consortium's interconnected, collaborative autopsy research is enabled by an unprecedented collaboration of 138 individuals at more than 35 German university and non-university autopsy centers through which pathology, neuropathology, and forensic medicine autopsy data including data on biomaterials are collected in DeRegCOVID and tissue-based research and methods development are conducted. More than 145 publications have now emerged from participating autopsy centers, highlighting various basic science and clinical aspects of COVID-19, such as thromboembolic events, organ tropism, SARS-CoV‑2 detection methods, and infectivity of SARS-CoV-2 at autopsy.

CONCLUSIONS

Participating centers have demonstrated the high value of autopsy and autopsy-derived data and biomaterials to modern medicine. The planned long-term continuation and further development of the registry and network, as well as the open and participatory design, will allow the involvement of all interested partners.

[Hemoptysis and acute kidney injury in COVID-19]

The present case describes the diagnostic and therapy of the pulmorenal syndrome of a 40-year-old patient who presented in our clinic due to increasing respiratory insufficiency and hemoptysis with confirmed COVID-19 disease.

Using Linked Health Service Data in The Evaluation of Innovative Models of Healthcare

IntroductionAgeing populations place considerable burden on healthcare systems. Innovative methods to implement and evaluate new care models to reduce unwarranted hospital presentations, are needed. Objectives and ApproachTo use linked Electronic Medical Record (EMR) data to evaluate a pilot community-based model of care to reduce hospital presentations in a cohort of patients at-risk of hospital representations following an acute admission. Patients admitted to a metropolitan hospital with a non-surgical condition andidentified as being at-risk of readmission using a state-wide risk algorithm, were eligible to receive a 30-day care navigation model of care. The intervention group were matched to similar eligible patients, who received usual care using propensity score matching. Linked data were obtained from the EMR based Data Warehouse to provide information on subsequent readmissions and community-based health service contacts. Readmission rates were compared at 30, 60, and 90-days post-discharge using Cox Proportional Hazards Regression, adjusted for confounders and weighted by the propensity score. Descriptive analyses were used to compare demographics and healthcare utilisations. ResultsData from 412,971 potentially eligible patients were extracted. Sixty-five received the intervention of which 63 were matched to 280 controls (aged 51-91 years, 54% female, 63% lived alone). At 30-days post-discharge (during intervention delivery) an 80% reduction in readmission rate in the intervention group was observed (Hazard Ratio [HR] 0.20; 95%Confidence Interval (CI) [0.01, 4.20]). At 60-days (HR 0.48; 95%CI [0.03, 8.05]) and 90-days (HR 0.83; 95%CI [0.06, 11.36]), readmission rate reductions decreased to 52% and 17% respectively. In the intervention group, 68.9% received an out-patient appointment compared to 40% of controls (P<0.001) and 7.7% received allied health compared to none of the controls (p=0.003) within 90-days post-discharge. Conclusion/ImplicationsResults have informed hospital-wide service implementation thereby demonstrating the value of linked EMR data and advanced statistical methods in the evaluation of real-world healthcare.

[Bed capacity management in times of the COVID-19 pandemic : A simulation-based prognosis of normal and intensive care beds using the descriptive data of the University Hospital Augsburg]

BACKGROUND

Following the regional outbreak in China, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spread all over the world, presenting the healthcare systems with huge challenges worldwide. In Germany the coronavirus diseases 2019 (COVID-19) pandemic has resulted in a slowly growing demand for health care with a sudden occurrence of regional hotspots. This leads to an unpredictable situation for many hospitals, leaving the question of how many bed resources are needed to cope with the surge of COVID-19 patients.

OBJECTIVE

In this study we created a simulation-based prognostic tool that provides the management of the University Hospital of Augsburg and the civil protection services with the necessary information to plan and guide the disaster response to the ongoing pandemic. Especially the number of beds needed on isolation wards and intensive care units (ICU) are the biggest concerns. The focus should lie not only on the confirmed cases as the patients with suspected COVID-19 are in need of the same resources.

MATERIAL AND METHODS

For the input we used the latest information provided by governmental institutions about the spreading of the disease, with a special focus on the growth rate of the cumulative number of cases. Due to the dynamics of the current situation, these data can be highly variable. To minimize the influence of this variance, we designed distribution functions for the parameters growth rate, length of stay in hospital and the proportion of infected people who need to be hospitalized in our area of responsibility. Using this input, we started a Monte Carlo simulation with 10,000 runs to predict the range of the number of hospital beds needed within the coming days and compared it with the available resources.

RESULTS

Since 2 February 2020 a total of 306 patients were treated with suspected or confirmed COVID-19 at this university hospital. Of these 84 needed treatment on the ICU. With the help of several simulation-based forecasts, the required ICU and normal bed capacity at Augsburg University Hospital and the Augsburg ambulance service in the period from 28 March 2020 to 8 June 2020 could be predicted with a high degree of reliability. Simulations that were run before the impact of the restrictions in daily life showed that we would have run out of ICU bed capacity within approximately 1 month.

CONCLUSION

Our simulation-based prognosis of the health care capacities needed helps the management of the hospital and the civil protection service to make reasonable decisions and adapt the disaster response to the realistic needs. At the same time the forecasts create the possibility to plan the strategic response days and weeks in advance. The tool presented in this study is, as far as we know, the only one accounting not only for confirmed COVID-19 cases but also for suspected COVID-19 patients. Additionally, the few input parameters used are easy to access and can be easily adapted to other healthcare systems.

Pesticides and antibiotics in permanent rice, alternating rice-shrimp and permanent shrimp systems of the coastal Mekong Delta, Vietnam

BACKGROUND

Salinity intrusion into coastal regions is an increasing threat to agricultural production of salt sensitive crops like paddy rice. In the coastal Mekong Delta, farmers respond by shifting to more salinity tolerant agricultural production systems such as alternating rice-shrimp and permanent shrimp. While shrimps are sensitive to pesticide residues used on rice, the use of antibiotics in shrimp farming can cause contamination in rice crops. These patterns of cross-contamination are not well documented empirically in the rapidly changing agricultural landscape.

OBJECTIVE AND METHODS

Our objective was to understand changing pollution patterns induced by shifts in agricultural land use system. We addressed this by i) documenting pesticide and antibiotic use in three different agriculture land use systems (permanent rice, alternating rice-shrimp and permanent shrimp), and by ii) determining residues of pesticides and antibiotics in top soil layers of these three land use systems. Samples were taken in Sóc Trăng and Bến Tre province in the Mekong Delta, Vietnam. Chemical analyses comprised 12 of the most commonly used pesticides in rice paddies and six common antibiotics used in shrimp production.

RESULTS

Results showed that residues of pesticides were present in all agricultural land use systems, including shrimp aquaculture. Active ingredients were mostly fungicides with a maximum concentration of 67 μg kg^-1 found for isoprothiolane in permanent rice systems, followed by alternating rice-shrimp and permanent shrimp systems. Furthermore, antibiotics were present ubiquitously, with fluoroquinolones accumulating to larger amounts than sulfonamides and diaminopyrimidines. All concentrations were below critical lethal threshold values.

CONCLUSION

Overall, farmers were most conscious of agrochemical use in alternating rice-shrimp systems to prevent harm to shrimps, which was reflected in overall lower concentrations of agrochemicals when compared to rice systems. Thus, alternating rice-shrimp systems present a low risk option in terms of food safety, which may bring additional benefits to this so far rather low-input system in brackish water transition zone.

Does sea-dyke construction affect the spatial distribution of pesticides in agricultural soils? - A case study from the Red River Delta, Vietnam

The Red River Delta is a major agricultural production area of Vietnam with year-round use of pesticides for paddy rice cultivation and other production systems. The delta is protected from flooding, storm surges and saline water intrusion by a sophisticated river and sea-dyke system. Little is known about the effects of such a dyke system on pesticide pollution in the enclosed landscape. Our aim was to address this gap by i) determining pesticide prevalence in soils and sediments within a dyked agricultural area, and by ii) assessing whether and to which degree this dyke system might affect the spatial distribution of pesticides. After sampling paddy rice fields (topsoil) and irrigation ditches (sediment) perpendicular to the dyke in Giao Thuy district, we analysed 12 of the most commonly used pesticides in this area. In soils, we detected most frequently isoprothiolane (100% detection frequency), chlorpyrifos (85%) and propiconazole (41%) while in sediments isoprothiolane (71%) and propiconazole (71%) were most frequently found. Maximum concentrations reached 42.6 μg isoprotiolane kg^-1 in soil, and 35.1 μg azoxystrobin kg^-1 in sediment. Our results supported the assumption that the dyke system influenced residue distribution of selected pesticides. More polar substances increasingly accumulated in fields closer to the sea-dyke (R² = 0.92 for chlorpyrifos and 0.51 for isoprothiolane). We can thus support initiatives from local authorities to use the distance to dykes as a mean for deliniating zones of different environmental pollution; yet, the degree at which dykes influence pesticide accumulation appear to be compound specific.

Porous Silicon Nanoparticle Delivery of Tandem Peptide Anti-Infectives for the Treatment of Pseudomonas aeruginosa Lung Infections

There is an urgent need for new materials to treat bacterial infections. In order to improve antibacterial delivery, an anti-infective nanomaterial is developed that utilizes two strategies for localization: i) a biodegradable nanoparticle carrier to localize therapeutics within the tissue, and ii) a novel tandem peptide cargo to localize payload to bacterial membranes. First, a library of antibacterial peptides is screened that combines a membrane-localizing peptide with a toxic peptide cargo and discovers a tandem peptide that displays synergy between the two domains and is able to kill Pseudomonas aeruginosa at sub-micromolar concentrations. To apply this material to the lung, the tandem peptide is loaded into porous silicon nanoparticles (pSiNPs). Charged peptide payloads are loaded into the pores of the pSiNP at ≈30% mass loading and ≈90% loading efficiency using phosphonate surface chemistry. When delivered to the lungs of mice, this anti-infective nanomaterial exhibits improved safety profiles over free peptides. Moreover, treatment of a lung infection of P. aeruginosa results in a large reduction in bacterial numbers and markedly improves survival compared to untreated mice. Collectively, this study presents the selection of a bifunctional peptide-based anti-infective agent and its delivery via biodegradable nanoparticles for application to an animal model of lung infection.

Porous Silicon Nanoparticle Delivery of Tandem Peptide Anti-Infectives for the Treatment of Pseudomonas aeruginosa Lung Infections

There is an urgent need for new materials to treat bacterial infections. In order to improve antibacterial delivery, an anti-infective nanomaterial is developed that utilizes two strategies for localization: i) a biodegradable nanoparticle carrier to localize therapeutics within the tissue, and ii) a novel tandem peptide cargo to localize payload to bacterial membranes. First, a library of antibacterial peptides is screened that combines a membrane-localizing peptide with a toxic peptide cargo and discovers a tandem peptide that displays synergy between the two domains and is able to kill Pseudomonas aeruginosa at sub-micromolar concentrations. To apply this material to the lung, the tandem peptide is loaded into porous silicon nanoparticles (pSiNPs). Charged peptide payloads are loaded into the pores of the pSiNP at ≈30% mass loading and ≈90% loading efficiency using phosphonate surface chemistry. When delivered to the lungs of mice, this anti-infective nanomaterial exhibits improved safety profiles over free peptides. Moreover, treatment of a lung infection of P. aeruginosa results in a large reduction in bacterial numbers and markedly improves survival compared to untreated mice. Collectively, this study presents the selection of a bifunctional peptide-based anti-infective agent and its delivery via biodegradable nanoparticles for application to an animal model of lung infection.

Early experience of a new extracorporeal carbon dioxide removal device for acute hypercapnic respiratory failure

BACKGROUND

Recent advances in the technology of extracorporeal respiratory assist systems have led to a renewed interest in extracorporeal carbon dioxide removal (ECCOR). The Hemolung is a new, low-flow, venovenous, minimally invasive, partial ECCOR device that has recently been introduced to clinical practice to aid in avoiding invasive ventilation or to facilitate lung-protective ventilation.

OBJECTIVE

We report our early experience on use, efficacy and safety of the Hemolung in three Australian intensive care units.

METHODS

Retrospective review of all patients with acute or acute-on-chronic respiratory failure (due to chronic obstructive pulmonary disease [COPD] with severe hypercapnic respiratory failure when non-invasive ventilation failed; acute respiratory distress syndrome; COPD; or asthma when lung-protective ventilation was not feasible due to hypercapnia) for whom the Hemolung was used.

RESULTS

Fifteen patients were treated with ECCOR. In four out of five patients, the aim of avoiding intubation was achieved. In the remaining 10 patients, the strategy of instituting lung-protective ventilation was successful. The median duration for ECCOR was 5 days (interquartile range, 3-7 days). The pH and PCO₂ improved significantly within 6 hours of instituting ECCOR, in conjunction with a significant reduction in minute ventilation. The CO₂ clearance was 90-100 mL/min. A total of 93% of patients survived to weaning from ECCOR, 73% survived to ICU discharge and 67% survived to hospital discharge.

CONCLUSION

Our data shows that ECCOR was safe and effective in this cohort. Further experience is vital to identify the patients who may benefit most from this promising therapy.

Low-flow veno-venous extracorporeal carbon dioxide removal in the management of severe status asthmatics: a case report

Status asthmaticus is a life-threatening condition that requires intensive care management. Most of these patients have severe hypercapnic acidosis that requires lung protective mechanical ventilation. A small proportion of these patients do not respond to conventional lung protective mechanical ventilation or pharmacotherapy. Such patients have an increased mortality and morbidity. Successful use of extracorporeal membrane oxygenation (ECMO) is reported in such patients. However, the use of ECMO is invasive with its associated morbidity and is limited to specialised centres. In this report, we report the use of a novel, minimally invasive, low-flow extracorporeal carbon dioxide removal device in management of severe hypercapnic acidosis in a patient with life threatening status asthmaticus.

Differential sensitivity of TREK-1, TREK-2 and TRAAK background potassium channels to the polycationic dye ruthenium red

BACKGROUND AND PURPOSE

Pharmacological separation of the background potassium currents of closely related K2P channels is a challenging problem. We previously demonstrated that ruthenium red (RR) inhibits TASK-3 (K2 P 9.1), but not TASK-1 (K2 P 3.1) channels. RR has been extensively used to distinguish between TASK currents in native cells. In the present study, we systematically investigate the RR sensitivity of a more comprehensive set of K2 P channels.

EXPERIMENTAL APPROACH

K(+) currents were measured by two-electrode voltage clamp in Xenopus oocytes and by whole-cell patch clamp in mouse dorsal root ganglion (DRG) neurons.

KEY RESULTS

RR differentiates between two closely related members of the TREK subfamily. TREK-2 (K2 P 10.1) proved to be highly sensitive to RR (IC50 = 0.2 μM), whereas TREK-1 (K2 P 2.1) was not affected by the compound. We identified aspartate 135 (D135) as the target of the inhibitor in mouse TREK-2c. D135 lines the wall of the extracellular ion pathway (EIP), a tunnel structure through the extracellular cap characteristic for K2 P channels. TREK-1 contains isoleucine in the corresponding position. The mutation of this isoleucine (I110D) rendered TREK-1 sensitive to RR. The third member of the TREK subfamily, TRAAK (K2 P 4.1) was more potently inhibited by ruthenium violet, a contaminant in some RR preparations, than by RR. DRG neurons predominantly express TREK-2 and RR-resistant TREK-1 and TRESK (K2 P 18.1) background K(+) channels. We detected the RR-sensitive leak K(+) current component in DRG neurons.

CONCLUSIONS AND IMPLICATIONS

We propose that RR may be useful for distinguishing TREK-2 (K2P 10.1) from TREK-1 (K2P 2.1) and other RR-resistant K2 P channels in native cells.

Notizen: „Rheniumcarbonylwasserstoff“ und Methylpentacarbonylrhenium

Im Anschluß an Untersuchungen über Manganpentacarbonylwasserstoff, HMn (CO)5, und Alkylmangancarbonyle, Mn(CO)5R, gelang erstmals die Darstellung von Hydrogenpentacarbonyl-rhenium (–I), HRe (CO)5, und Methylpentacarbonylrhenium, CH3Re (CO)5, aus Alkalipentacarbonylrhenat (–I). Das Hydrid HRe(CO)5, eine luftempfindliche, bei gewöhnlicher Temperatur farblose Flüssigkeit, zersetzt sich erst oberhalb 100° in dimeres Rheniumpentacarbonyl und Wasserstoff. Die in farblosen Kristallen anfallende Methylverbindung ist sehr stabil, leicht flüchtig und schmilzt bei 120°. Insgesamt zeigen die Carbonylhydride und „Organometallcarbonyle“ von Mangan und Rhenium hinsichtlich ihrer Beständigkeit ein typisches Sonderverhalten.

Notizen: Über Methylkobalttetracarbonyl

In Analogie zum Methylmanganpentacarbonyl gelang erstmals die Darstellung des Methylesters des Kobaltcarbonylwasserstoffs, CH3Co(CO)4. Im Gegensatz zu dem auffallend stabilen CH3Mn(CO)5 ist CH,Co(CO)4 eine sehr labile, nur bei tiefen Temperaturen beständige Verbindung. Indessen konnten aus dem IR-Spektrum im gasförmigen Zustand wichtige Aufschlüsse über ihre Struktur erhalten werden

Management of severe hypercapnia post cardiac arrest with extracorporeal carbon dioxide removal

Normocapnia is recommended in intensive care management of patients after out-of-hospital cardiac arrest. While normocapnia is usually achievable, it may be therapeutically challenging, particularly in patients with airflow obstruction. Conventional mechanical ventilation may not be adequate to provide optimal ventilation in such patients. One of the recent advances in critical care management of hypercapnia is the advent of newer, low-flow extracorporeal carbon dioxide clearance devices. These are simpler and less invasive than conventional extracorporeal devices. We report the first case of using a novel, extracorporeal carbon dioxide removal device in Australia on a patient with out-of-hospital cardiac arrest where mechanical ventilation failed to achieve normocapnia.

Dependence of maternal serum [AFP]/[hCG] median ratios on age of gestation: comparison of trisomy 21 to euploid pregnancies

BACKGROUND

Current risk calculations for trisomy 21, which are based on multiples of median (MoM), do not take into account possible differences between euploid and trisomy 21 pregnancies that may develop with gestational age. In order to optimize the predictive value of screening tests, we calculated the ratio between maternal serum concentration of alpha-fetoprotein (AFP) and that of human chorionic gonadotropin (hCG) in euploid and in trisomy 21 pregnancies.

METHODS

The medians of the concentration ratios, [AFP]/[hCG] at 16-21 weeks of gestation, were plotted as a function of gestational age for 307 cases of trisomy 21 and were compared with the medians of 30 549 normal karyotype cases.

RESULTS

[AFP]/[hCG] ratio medians were independent of body weight and maternal age. There was a significant difference in the [AFP]/[hCG] ratio when comparing trisomy 21 and euploid pregnancies at each week. This difference became greater with advancing gestational age (P < 0.01).

CONCLUSION

There is a significant difference in ratios of [AFP]/[hCG] between euploid and trisomy 21 pregnancies, which may be used to improve detection rates of Down syndrome screening.

[Cardiac amyloidosis--cardiovascular magnetic resonance imaging as a valuable diagnostic tool]

HISTORY

A 90-year-old man presented at the emergency room with symptoms of severe heart failure. A few weeks earlier he had been seen with the same symptoms at another hospital where the diagnosis of severe aortic valve stenosis had been made and aortic valve replacement was recommended. However, the patient did not consent to surgery and was discharged after medical treatment.

INVESTIGATIONS

Echocardiography demonstrated global hypertrophy, pronounced at the ventricular septum. Interestingly the transaortic pressure gradient was only slightly elevated, revealing mild aortic stenosis. Thus, for work-up of discrepancies between the recent and previous (in the other hospital) exam results, cardiac magnetic resonance imaging (CMR) was performed.

DIAGNOSIS

CMR planimetry confirmed that the aortic stenosis was only mild. However, contrast CMR revealed typical circular subendocardial late gadolinium enhancement in the entire left ventricle, which is typically seen in cardiac amyloidosis. This diagnosis was confirmed by endomyocardial biopsy revealing transthyretin-type amyloidosis.

TREATMENT AND COURSE

Recompensation was achieved using diuretics and usual heart failure medication. Unfortunately, there is no causal treatment for transthyretin-type amyloidosis. However, the unnecessary aortic valve replacement surgery could be avoided.

CONCLUSION

CMR is capable to precisely assess the aortic valve area even in cases with discrepant findings by other techniques. In addition, contrast CMR allows noninasive detection of myocardial abnormalities in living patients. Based on the pattern of contrast enhancement, differentiation between etiologies is possible.

Rapid, solution-based characterization of optimized SERS nanoparticle substrates

We demonstrate the rapid optical characterization of large numbers of individual metal nanoparticles freely diffusing in colloidal solution by confocal laser spectroscopy to guide nanoparticle engineering and optimization. We use ratios of the Rayleigh and Raman scattering response and rotational diffusion timescales of individual nanoparticles to show that hollow gold nanospheres and solid silver nanoparticle dimers linked with a bifunctional ligand, both specifically designed nanostructures, exhibit significantly higher monodispersity than randomly aggregated gold and silver nanoparticles.

Enzyme-directed positioning of nanoparticles on large DNA templates

A method to position nanoparticles onto DNA with high resolution using an enzyme-based approach is described. This provides a convenient route to assemble multiple nanoparticles (e.g., Au and CdSe) to specific positions with a high level of control and expandability to more complex assemblies. Atomic force microscopy is used to analyze the nanostructures, which have potential interest for biosensor, optical waveguide, molecular electronics, and energy transfer studies.

Detection of sequence-specific protein-DNA interactions via surface enhanced resonance Raman scattering

We developed a new strategy to detect protein-DNA binding through surface enhanced resonance Raman scattering (SERRS). Silver-plated DNA and gold nanoparticle assemblies were used to identify sequence-specific and concentration-dependent binding of a DNA cytosine-C5-methyltransferase and the eukaryotic transcriptional regulator, TATA binding protein. Proteins were identified through specific Raman-active labels, and affinities observed correlate well with those determined by other methods. Raman-active labeling and interchangeable DNA sequences create a platform for versatile investigation of multiprotein complexes.

Fluorescence microscopic visualization and quantification of initial bacterial colonization on enamel in situ

OBJECTIVE

The acquired salivary pellicle has been defined as proteinaceous film free of bacteria. However, due to the large numbers of microorganisms existent in the oral fluids, it is conceivable that adherent bacteria are already present in the initial pellicle. The aim of this in situ study was to visualize and to quantify these bacteria.

DESIGN

Initial biofilm formation was performed on bovine enamel slabs mounted buccally on individual splints and carried in situ by six subjects for 3, 30 and 120 min, respectively. After intraoral exposure, the slabs were rinsed with saline solution and the adherent bacteria were investigated with the following fluorescence microscopic methods: staining with 4',6-diamidino-2-phenylindole (DAPI), staining of vital and nonvital bacteria with fluoresceinediacetate and ethidiumbromide (live/dead staining) and fluorescence in situ hybridization (FISH) of eubacteria and streptococci, respectively. In addition, determination of colony forming units after ultrasonically induced detachment of bacteria was performed.

RESULTS

With all the methods, bacteria were detected in the initial in situ biofilm irrespective of the formation time. The numbers of bacteria revealed high intraindividual and interindividual variability and the microorganisms were distributed randomly in small aggregates. The results of the epifluorescence microscopic techniques corresponded well. The mean number of adherent bacteria detected was in the range of 10-20x10(4)cm(-2).

CONCLUSION

Already after 3 min, adherent bacteria are present in the initial pellicle. For the first time, DAPI-staining as well as FISH have proven success for visualization of initial intraoral colonization of enamel specimens.

Specific and sensitive detection of nucleic acids and RNases using gold nanoparticle-RNA-fluorescent dye conjugates

Gold nanoparticles were modified with RNA and utilized to detect specific DNA sequences and various RNA nucleases.

The initial stage of uranium oxidation: mechanism of UO(2) scale formation in the presence of a native lateral stress field

In this work, an oxidation model for alpha-uranium is presented. It describes the internally lateral stress field built in the oxide scale during the reaction. The thickness of the elastic, stress-preserving oxide (UO(2+x)) scale is less than 0.5 microm. A lateral, 6.5 GPa stress field has been calculated from strains derived from line shifts (delta(2theta)) as measured by the X-ray diffraction of UO(2). It is shown that in the elastic growth domain, (110) is the main UO(2) growth plane for gas-solid oxidation. The diffusion-limited oxidation mechanism discussed here is based on the known "2:2:2" cluster theory which describes the mechanism of fluorite-based hyperstoichiometric oxides. In this study, it is adapted to describe oxygen-anion hopping. Anion hopping toward the oxide-metal interface proceeds at high rates in the [110] direction, hence making this pipeline route the principal growth direction in UO(2) formation. It is further argued that growth in the pure elastic domain of the oxide scale should be attributed entirely to anion hopping in 110. Anions, diffusing isotropically via grain boundaries and cracks, are shown to have a significant impact on the overall oxidation rate in relatively thick (>0.35 microm) oxide scales if followed by an avalanche break off in the postelastic regime. Stress affects oxidation in the elastic domain by controlling the hopping rate directly. In the postelastic regime, stress weakens hopping, indirectly, by enhancing isotropic diffusion. Surface roughness presents an additional hindering factor for the anion hopping. In comparison to anisotropic hopping, diffusion of isotropic hopping has a lower activation energy barrier. Therefore, a relatively stronger impact at lower temperatures due to isotropic diffusion is displayed.

Controlled spacing of cationic gold nanoparticles by nanocrown RNA

Using atomic force microscopy, we describe the linear arrangement of cationic gold nanoparticles directed by programmable self-assembling RNA ladders and demonstrate that the regular spacing of nanoparticles is controlled by the RNA architecture acting as nanocrown scaffoldings. Thus, precise positioning of molecular components can be accomplished with RNA not only through electrostatic but also via size and shape recognitions.