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We report the bottom-up synthesis of colloidal two-dimensional (2D) layered silicon carbide (SiC) quantum dots with a cubic structure, lateral size of 5-10 nm, ⟨110⟩ exfoliation to few atomic layers, and surface passivation with 1-dodecene. Samples shielded from oxygen and plasma-annealed for purity exhibit narrow blue photoluminescence (PL) with quantum yields (QYs) over 60% in exceptional cases, while unshielded nanocrystals (NCs) exhibit broad blue/green/white PL with 10-15% QY. The latter scenario is attributed to excess surface carbon and oxygen accrued during synthesis and processing, with size separation through ultracentrifugation revealing size-dependent impurity emission. In contrast, the shape of the bright narrow blue PL shows little variation with NC size, while in both scenarios, the maximum QY occurs near four atomic layers. When dried under heat, the disk-like NC suspensions are observed to aggregate into microscale domains, with further self-assembly into planar superlattice domains with common crystalline orientation. The results are compared with photophysical simulations and bring clarity to the broad emission commonly reported for top-down approaches, while inspiring bottom-up schemes directed at improved material quality.

Poly(UG) or "pUG" RNAs are UG or GU dinucleotide repeat sequences which are highly abundant in eukaryotes. Post-transcriptional addition of pUGs to RNA 3' ends marks mRNAs as vectors for gene silencing in C. elegans. We previously determined the crystal structure of pUG RNA bound to the ligand N-methyl mesoporphyrin IX (NMM), but the structure of free pUG RNA is unknown. Here we report the solution structure of the free pUG RNA (GU) 12 , as determined by nuclear magnetic resonance spectroscopy and small and wide-angle x-ray scattering (NMR-SAXS-WAXS). The low complexity sequence and 4-fold symmetry of the structure result in overlapped NMR signals that complicate chemical shift assignment. We therefore utilized single site-specific deoxyribose modifications which did not perturb the structure and introduced well-resolved methylene signals that are easily identified in NMR spectra. The solution structure ensemble has a root mean squared deviation (RMSD) of 0.62 Å and is a compact, left-handed quadruplex with a Z-form backbone, or "pUG fold." Overall, the structure agrees with the crystal structure of (GU) 12 bound to NMM, indicating the pUG fold is unaltered by docking of the NMM ligand. The solution structure reveals conformational details that could not be resolved by x-ray crystallography, which explain how the pUG fold can form within longer RNAs., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier Ltd.)

Prolonged waterlogging in agricultural fields has severe consequences for the crop development and growth, and could potentially lead to higher N losses. In this study, a 3.93 ha agricultural field in Denmark was separated into two parts of well-drained (WD) and poorly-drained (PD) based on the installation depth of the tile drains. The field was continuously monitored for drainage, soil water dynamics, nitrogen leaching through the drains, and grain dry matter and nitrogen yields in a 4-year period (2017-2020). Furthermore, denitrification potential of the top 1 m of the soil at both parts of the field was measured through the denitrifying enzyme activity assay, and a 1D Daisy model was utilized to capture the differences between water and nitrogen balances at WD and PD. Results indicated that on average over the 4 years, annual harvested nitrogen in the crops at PD was 14% lower compared to WD, with a significant reduction of 33% in 2017-2018, that coincided with the longest period of waterlogging at PD. Moreover, greater losses of nitrogen through leaching from drainage and other pathways were measured at the PD (109 kg N ha -1 ya -1 ) compared to the WD (95 kg N ha -1 ya -1 ). Based on the simulations, losses through preferential flow pathways to the drains dominated at PD and most of the denitrification is expected to occur within the topsoil. Future studies could significantly benefit from monitoring the redox dynamics in the top 30 cm of the PD soils, and increasing the depth of tiles drains by redrainage could reduce the N losses of poorly drained agricultural soils., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022. Published by Elsevier Ltd.)

The addition of poly(UG) ('pUG') repeats to 3' termini of mRNAs drives gene silencing and transgenerational epigenetic inheritance in the metazoan Caenorhabditis elegans. pUG tails promote silencing by recruiting an RNA-dependent RNA polymerase (RdRP) that synthesizes small interfering RNAs. Here we show that active pUG tails require a minimum of 11.5 repeats and adopt a quadruplex (G4) structure we term the pUG fold. The pUG fold differs from known G4s in that it has a left-handed backbone similar to Z-RNA, no consecutive guanosines in its sequence, and three G quartets and one U quartet stacked non-sequentially. The compact pUG fold binds six potassium ions and brings the RNA ends into close proximity. The biological importance of the pUG fold is emphasized by our observations that porphyrin molecules bind to the pUG fold and inhibit both gene silencing and binding of RdRP. Moreover, specific 7-deaza substitutions that disrupt the pUG fold neither bind RdRP nor induce RNA silencing. These data define the pUG fold as a previously unrecognized RNA structural motif that drives gene silencing. The pUG fold can also form internally within larger RNA molecules. Approximately 20,000 pUG-fold sequences are found in noncoding regions of human RNAs, suggesting that the fold probably has biological roles beyond gene silencing., (© 2022. The Author(s), under exclusive licence to Springer Nature America, Inc.)

We performed x-ray photoelectron spectroscopy measurements on a thin film of Si nanocrystals (SiNCs) while applying DC or AC external biases to extract the resistance and the capacitance of the thin film. The measurement consists of the application of 10 V DC or square wave pulses of 10 V amplitude to the sample at various frequencies ranging from 0.01 to 1 MHz while recording x-ray photoemission data. To analyze the data, we propose three different models with varying degrees of accuracy. The calculated capacitance of SiNCs agrees with the experimental value in the literature.

Excess nitrogen (N) losses from intensive agricultural production are a world-wide problem causing eutrophication in vulnerable aquatic ecosystems such as estuaries. Therefore, Denmark as one of the most intensively farmed countries in the world has enforced mandatory regulations on agricultural production since the late 1980s. We demonstrate the outcome of the regulations imposed on agriculture by analyzing decadal trends in nitrate (NO 3 - ) concentrations and loads in streams using 29 years of detailed monitoring data and survey information on agricultural practices at field level from five intensively cultivated headwater catchments. The analysis includes the importance of four main drivers (climate, land use, agricultural practices, and biogeophysical properties of catchments), each divided into different factors that may influence stream NO 3 - loads during three subperiods defined by the time of introduction of different mitigation measures: i) 1990-1998, ii) 1999-2007, and iii) 2008-2018. Significant correlations with annual flow-weighted stream NO 3 - concentrations and/or loads were found for factors representing all of the four main drivers including precipitation, large scale climate fluctuations, runoff, previous year's runoff, baseflow index, number of annual frost days, agricultural area, livestock density, field N surplus, catch crop cover, manure storage capacity, method and time of manure spreading, and time of soil tillage. Changes in the four drivers were reflected by the load-runoff (L-Q) relationships for each of the three subperiods within each of the five headwater catchments. The five catchments experienced large but catchment-specific downward shifts in the L-Q relationship attributable to changes in land use and agricultural management within the catchments. The documented large downward shifts in NO 3 - loads demonstrated for the five catchments (30-52%) as a consequence of mandatory regulation over a period of nearly three decades are a unique example of how agriculture can reduce its environmental impact., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 The Authors. Published by Elsevier B.V. All rights reserved.)

Using a combination of density-gradient and analytical ultracentrifugation, we studied the photophysical profile of CsPbBr 3 nanocrystal (NC) suspensions by separating them into size-resolved fractions. Ultracentrifugation drastically alters the ligand profile of the NCs, which necessitates postprocessing to restore colloidal stability and enhance quantum yield (QY). Rejuvenated fractions show a 50% increase in QY compared to no treatment and a 30% increase with respect to the parent. Our results demonstrate how the NC environment can be manipulated to improve photophysical performance, even after there has been a measurable decline in the response. Size separation reveals blue-emitting fractions, a narrowing of photoluminescence spectra in comparison to the parent, and a crossover from single- to stretched-exponential relaxation dynamics with decreasing NC size. As a function of edge length, L , our results confirm that the photoluminescence peak energy scales a L -2 , in agreement with the simplest picture of quantum confinement.

Wetland buffer zones (WBZs) are riparian areas that form a transition between terrestrial and aquatic environments and are well-known to remove agricultural water pollutants such as nitrogen (N) and phosphorus (P). This review attempts to merge and compare data on the nutrient load, nutrient loss and nutrient removal and/or retention from multiple studies of various WBZs termed as riparian mineral soil wetlands, groundwater-charged peatlands (i.e. fens) and floodplains. Two different soil types ('organic' and 'mineral'), four different main water sources ('groundwater', 'precipitation', 'surface runoff/drain discharge', and 'river inundation') and three different vegetation classes ('arboraceous', 'herbaceous' and 'aerenchymous') were considered separately for data analysis. The studied WBZs are situated within the temperate and continental climatic regions that are commonly found in northern-central Europe, northern USA and Canada. Surprisingly, only weak differences for the nutrient removal/retention capability were found if the three WBZ types were directly compared. The results of our study reveal that for example the nitrate retention efficiency of organic soils (53 ± 28%; mean ± sd) is only slightly higher than that of mineral soils (50 ± 32%). Variance in load had a stronger influence than soil type on the N retention in WBZs. However, organic soils in fens tend to be sources of dissolved organic N and soluble reactive P, particularly when the fens have become degraded due to drainage and past agricultural usage. The detailed consideration of water sources indicated that average nitrate removal efficiencies were highest for ground water (76 ± 25%) and lowest for river water (35 ± 24%). No significant pattern for P retention emerged; however, the highest absolute removal appeared if the P source was river water. The harvesting of vegetation will minimise potential P loss from rewetted WBZs and plant biomass yield may promote circular economy value chains and provide compensation to land owners for restored land now unsuitable for conventional farming., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Silicon nanocrystals (SiNCs) with bright bandgap photoluminescence (PL) are of current interest for a range of potential applications, from solar windows to biomedical contrast agents. Here, we use the liquid precursor cyclohexasilane (Si 6 H 12 ) for the plasma synthesis of colloidal SiNCs with exemplary core emission. Through size separation executed in an oxygen-shielded environment, we achieve PL quantum yields (QYs) approaching 70% while exposing intrinsic constraints on efficient core emission from smaller SiNCs. Time-resolved PL spectra of these fractions in response to femtosecond pulsed excitation reveal a zero-phonon radiative channel that anticorrelates with QY, which we model using advanced computational methods applied to a 2 nm SiNC. Our results offer additional insight into the photophysical interplay of the nanocrystal surface, quasi-direct recombination, and efficient SiNC core PL.

A novel macrocyclic host molecule was synthesized that forms in a single step from commercially available starting materials. The core of the macrocycle backbone possesses two quinone rings and, thus, it is redox-active. Host-guest binding involving the clip-shaped cavity indicates selective binding of pyridine N-oxides based on the electron density of and steric bulk around the anionic oxygen., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

This feasibility study set out to investigate the use of FDG-PET/DW-MRI in chronic hepatitis C patients to examine changes in local liver inflammation after treatment with direct-acting antivirals (DAA). Twelve patients with chronic hepatitis C were prospectively enrolled, performing FDG-PET/DW-MRI prior to and after DAA treatment. PET/DW-MRI included PET acquisition 60 and 90 min after FDG-injection, DIXON, for attenuation correction, T2- and DW-MRI with 10 b-values between 0-700 s/mm 2 . The following parameters were measured from fusion of 3 volumes of interest (VOIs) placed in the liver parenchyma: Mean standard uptake value after 60 and 90 minutes (SUV mean60 and SUV mean90 ), total Apparent Diffusion Coefficient (ADC), perfusion fraction (PF), pseudo-diffusion (D*) and perfusion-free diffusion (D). We found PET/DW-MRI of chronic hepatitis C patients to be feasible. Patients were cooperative, tolerated the scans well and the image quality was acceptable. A total of 10 patients were available for final analysis. All patients achieved sustained virologic response and normalized alanine -aminotransferase (ALAT) levels after treatment with DAA. Perfusion fraction measured by DW-MRI changed significantly after treatment, from mean 0.21 (± 0.04) to 0.26 (± 0.06), P=0.005 and D* from 0.50 (± 0.13) × 10 -3 s/mm 2 to 0.62 (± 0.15) × 10 -3 s/mm 2 , P=0.028. All other parameters, including FDG-uptake, was unchanged. These results suggest that liver perfusion is changed shortly after DAA treatment, with no significant change in inflammation. The study concludes that PET/DW-MR is feasible in quantifying perfusion and possibly inflammation in chronic hepatitis C patients and may be used to follow treatment., Competing Interests: None.

Introduction: Game-based interventions have been proposed as a way to improve both patient adherence to physical activity (PA) and disease-related knowledge to achieve better self-management of blood glucose levels (HbA1c). The objective of this study was to systematically review the literature on the effect of game-based interventions on HbA1c, diabetes-related knowledge, and physical outcomes in rehabilitation of diabetes patients., Methods: We conducted a systematic literature search in MEDLINE, EMBASE, PEDro, Scopus, Cochrane Central Register of Controlled Trials, CINAHL, and Psych INFO in October 2014 based on a priori defined inclusion criteria: patients with diabetes (type 1 or type 2), game-based interventions, and randomized controlled trials., Results: The database search identified 1,101 potential articles for screening, four of which were eligible for the present systematic review. Game-based interventions show no effect on HbA1c (three studies) standardized mean difference = -0.10, 95% confidence interval = [-0.33, 0.14] compared to usual care or waiting lists. Game-based interventions were superior to controls in improving health-related quality of life, muscle strength, and balance (one study). No difference was found between game-based interventions and usual care or waiting lists in terms of diabetes-related knowledge (one study)., Discussion: PA is important for diabetes management. The present review indicates that game-based interventions are not superior to ordinary PA in controlling HbA1c. Due to the weak methodological quality of the included studies and the very low body of evidence, the likelihood that the real effect of game-based interventions will be substantially different (i.e., large enough difference to possibly affect decision-making) is high.

Objective: Patients with PPROM are at risk for a variety of outcomes, including chorioamnionitis (CA), placental abruption (PA), or preterm labor (PTL). Competing risk regression can analyze a cohort's risk of individual outcomes while accounting for ongoing deliveries secondary to competing events., Methods: A secondary analysis of the subjects from MFMU BEAM study of neuroprotection after preterm birth (BEAM) with conservative PPROM management. Deliveries were categorized as: PA, CA, PTL, "elective" or "indicated". The association between outcomes of PA, CA or PTL and clinical predictors of twins, ethnicity, parity, gestational age at rupture, bleeding, contractions, cervical dilation, preterm birth history, weight, and genitourinary infections were evaluated via competing risk regression., Result: 1970 subjects were included. The significance and directionality of predictors varied according to specific outcomes. Patients with twins had an increased PTL hazard (1.85) though reductions in CA- (0.66) or PA-specific (0.56) hazards. Decreased latency in African-Americans was almost entirely due to an increased CA hazard (1.44) without a significant association with PTL. Increasing gestational age at membrane rupture was associated with a decreasing hazard of CA although increasing hazard of PTL., Conclusions: For patients with PPROM, the hazards associated with different clinical predictors vary according to exact outcomes.

Context: Previous trials of off-pump coronary artery bypass (OPCAB) have enrolled selected patients and have not rigorously evaluated long-term graft patency. A preliminary report showed OPCAB achieved improved inhospital outcomes, similar completeness of revascularization, and shorter lengths of stay compared with conventional coronary artery bypass grafting (CABG)., Objective: To assess graft patency, clinical and quality-of-life outcomes, and cost among patients while in the hospital and at 1-year follow-up., Design, Setting, and Patients: Randomized controlled trial of patients unselected for coronary anatomy, ventricular function, or comorbidities between March 10, 2000, and August 20, 2001, at a US academic center. A total of 200 patients were enrolled; 3 patients were withdrawn after randomization for mitral valve repair or replacement. Follow-up was complete for 197 patients at 30 days; 185 at 1 year., Interventions: One surgical session consisting of elective OPCAB or CABG with cardiopulmonary bypass. The surgeon had extensive experience performing off-pump surgery; patients were subsequently managed by blinded protocols., Main Outcome Measures: Coronary angiography documented graft patency prior to hospital discharge and at 1 year; health-related quality of life; and cost of the index and subsequent hospitalization(s)., Results: Graft patency was similar for OPCAB and conventional CABG with cardiopulmonary bypass at 30 days (absolute difference, 1.3%; 95% confidence interval [CI], -0.66% to 3.31%; P =.19) and at 1 year (absolute difference, -2.2%; 95% CI, -6.1% to 1.7%; P =.27). Rates of death, stroke, myocardial infarction, angina, and reintervention were similar at 30 days and 1 year. There were no significant differences in health-related quality of life. Mean total hospitalization cost per patient at hospital discharge was 2272 dollars (95% CI, 755 dollars-3732 dollars) less for OPCAB (P =.002) and 1955 dollars (95% CI, -766 dollars to 4727 dollars) less at 1 year (P =.08)., Conclusions: In this randomized single-surgeon trial among unselected patients with angiographic follow-up, OPCAB achieved similar graft patency in the hospital and at 1 year. Cardiac outcomes and health-related quality of life at 30 days and 1 year were similar and patients incurred a lower cost. OPCAB may provide complete revascularization that is durable and cost-effective.

Objective: Off-pump coronary artery bypass (OPCAB) hopes to avoid morbidity associated with cardiopulmonary bypass, improving clinical outcomes. Yet its technical difficulty and unfamiliarity raise concern that adoption of OPCAB might be associated with poorer outcomes during each surgeon's 'learning curve'. We examined trends in patient selection over time as a single surgeon's practice evolved to routine OPCAB., Methods: Between 10-1-96 and 12-31-01, 1479 consecutive patients had isolated coronary artery bypass grafting (CABG). Clinical data were gathered prospectively and reviewed retrospectively. Trends in adoption of OPCAB and clinical outcomes were examined., Results: There were 756 OPCAB and 723 CABG/cardiopulmonary bypass patients. The practice evolved from 90% conventional CABG to 93% OPCAB. An abrupt transition coincided with evolution of techniques to expose the obtuse marginal arteries, and improvements in suction-based coronary stabilizers. Mortality was 1.0% for the off-pump group and 2.1% for the on-pump group. Careful patient selection helped maintain acceptable outcomes during the 'learning curve'. Patients with depressed left ventricular ejection fraction, left main disease, and complex three vessel disease were excluded from OPCAB until significant experience (>200 cases) was attained. Presently, all isolated coronary bypass cases are candidates for OPCAB except patients with ischemic ventricular arrhythmias, those in cardiac arrest, and those for whom previous left pneumonectomy or deep pectus excavatum prevent rightward mobilization of heart., Conclusions: Despite a significant learning curve, evolution to routine OPCAB can be achieved while maintaining good patient outcomes. The development of specialized techniques, coronary stabilizers, and apical suction devices allows the application of OPCAB to virtually all coronary bypass patients, as surgeon experience matures.

Cardiovascular disease remains a significant source of morbidity and mortality for patients with kidney disease. Coincident with the development of chronic renal failure, patients typically manifest a systemic vasculopathy often involving the cardiovascular system. The renal failure patient is also plagued by multiple comorbid conditions that may adversely affect cardiovascular outcomes. Consistent with the national trend of increasing numbers of patients requiring renal replacement therapy (RRT), patients requiring invasive cardiovascular procedures are also on the incline. The morbidity and mortality related to these procedures has remained high despite significant advances in delivery and maintenance of care. Is the African-American patient with renal failure unique in terms of cardiovascular morbidity and mortality? Numerous studies have documented racial differences in access to invasive cardiovascular procedures, even after controlling for multiple physiologic risk factors and socioeconomic and sociocultural factors. Studies have also shown higher morbidity and lower survival for African-American patients after cardiac procedures. In this high-risk population these same issues perhaps would persist. The following paper will examine the current status of cardiovascular disease in the renal failure patient with emphasis on the African-American patient population.

Objective: Retrospective comparisons of selected patients undergoing off-pump versus conventional on-pump coronary artery bypass grafting have yielded inconsistent results and raised concerns about completeness of revascularization in off-pump coronary artery bypass grafting., Methods: Two hundred unselected patients referred for elective primary coronary artery bypass grafting were randomly assigned to undergo off-pump coronary artery bypass grafting with an Octopus tissue stabilizer (Medtronic, Inc, Minneapolis, Minn) or conventional coronary artery bypass grafting with cardiopulmonary bypass by a single surgeon. Revascularization intent determined before random assignment was compared with the revascularization performed. All management followed strict, unbiased, criteria-driven protocols. Patients and nonoperative care providers were blinded to surgical group., Results: Baseline characteristics were similar. The number of grafts performed per patient (mean +/- SD 3.39 +/- 1.04 for off-pump coronary artery bypass grafting, 3.40 +/- 1.08 for conventional coronary artery bypass grafting) and the index of completeness of revascularization (number of grafts performed/number of grafts intended, 1.00 +/- 0.18 for off-pump coronary artery bypass grafting, 1.01 +/- 0.09 for conventional coronary artery bypass grafting) were similar. Likewise, the index of completeness of revascularization was similar between groups for the lateral wall. Combined hospital and 30-day mortalities and stroke rates were similar. Postoperative myocardial serum enzyme measures were significantly lower after off-pump coronary artery bypass grafting, suggesting less myocardial injury. Adjusted postoperative thromboelastogram indices, fibrinogen, international normalized ratio, and platelet levels all showed significantly less coagulopathy after off-pump coronary artery bypass grafting. Patients undergoing off-pump coronary artery bypass grafting received fewer units of blood, were more likely to avoid transfusion altogether, and had a higher hematocrit at discharge. Cardiopulmonary bypass was an independent predictor of transfusion (odds ratio 2.42, P =.0073) by multivariate analysis. More patients undergoing off-pump coronary artery bypass grafting were extubated in the operating room and within 4 hours. Postoperative length of stay (in days) was shorter for off-pump coronary artery bypass grafting (5.1 +/- 6.5 for off-pump coronary artery bypass grafting, 6.1 +/- 8.2 for conventional coronary artery bypass grafting, P =.005 by Wilcoxon test). One patient (in the conventional coronary artery bypass grafting group) required angioplasty for graft closure within 30 days., Conclusions: When compared with conventional coronary artery bypass grafting with cardiopulmonary bypass, off-pump coronary artery bypass grafting achieved similar completeness of revascularization, similar in-hospital and 30-day outcomes, shorter length of stay, reduced transfusion requirement, and less myocardial injury.

Objective: Literature review found little information on off-pump coronary artery bypass (OPCAB) procedure in patients with poor left ventricular function and there was no information comparing the low EF and normal EF patients undergoing OPCAB procedure., Methods: Between 1/1/1998 and 6/30/1999, 387patients had surgery performed utilizing the off-pump technique and 45 of these patients had pre-operative left ventricular function of equal to or less than 30% (LVEF < or =30). The two groups (LVEF < or =30 and LVEF>30) were compared using univariate analysis. Patients in LVEF < or =30 were older and more female gender. LVEF< 30 had more NYHA class IV patients (64 vs. 50%) and more symptoms related to depressed left ventricular function. The mean pre-operative left ventricular function was 25% in LVEF < or =30 and 56% in LVEF>30. Pre-operative predicted risk was 6.4+/-5.5% in LVEF < or =30 and 2.7+/-4.5% in LVEF>30 (P< 0.001). Most (> 95%) of the patients in both groups were elective status, and LVEF < or =30 patients had increased incidence of redo (11 vs. 6%, P=0.2). In LVEF>30, 84% of the patients had stable angina while only 69% in LVEF < or =30 (P=0.009)., Results: Intra-operatively no significant differences were measured in number of grafts per patient (2.7 vs. 2.8), amount of blood loss, peak CK-MB, skin-to-skin time, or OR time. Patients with LVEF < or =30 have more frequent utilization IABP during pre, intra and post-operative period. The statistical analysis yields no significance in post-operative major neurological deficit between these two groups; and are comparative to the nationally reported incidence of neurological deficit for on-pump patients. The operative mortality in the low EF group was 4.4 and 1.8% in LVEF>30 group (P=0.23)., Conclusions: Given the clinical presentation of the low EF group, higher prediction risk, longer pre-operative stay, and length of ventilation (24 vs. 8 h P=0.12) a longer surgery to discharge stay (8 vs. 6 days, P=0.02) is anticipated. Short-term clinical outcomes for both groups of OPCAB patients encouraged us to continue to offer this approach to this broad base of patient population.

From January 1, 1997 through June 30, 2000, 224 patients underwent valve replacement with the ATS Medical cardiac valve prosthesis under a USFDA-approved investigational device exemption study. Aortic valve replacement (AVR) was conducted in 152 patients (39 with coronary bypass) and mitral replacement (MVR) in 72 patients (18 with coronary bypass). Overall operative mortality was 1.8% (AVR = 2.8%, MVR = 0%), with only one valve-related death. In 372 patient-years of follow-up, there were an additional four patient deaths, two of which were valve related following a stroke. Valve-related complications included: thromboembolism (linearized rate = 3.8% per patient year), of which 3/11 had chronic deficits (0.8% per patient year); thrombosis (1 MVR = 0.8% per patient year); paravalvular leak (1 AVR = 0.4% per patient year); anticoagulant-related hemorrhage (1 AVR and 5 MVR = 1.6% per patient year) with no patient mortality; prosthetic valve endocarditis (1 MVR = 0.8% per patient year); and valve dysfunction (0%). Echocardiographic gradients were proportional to valve size and did not significantly change over the follow-up period. This study documented the ATS Medical prosthesis to be a valuable addition to the surgeon's armamentarium in the treatment of cardiac valvular disease.

Background: Does the manipulation of the heart during off-pump coronary artery bypass (OPCAB) procedure further compromise the hemodynamic stability of a patient with depressed left ventricular function compared with the conventional coronary artery bypass (CCAB) approach? Does this manipulation induce a more dramatic hypoperfused state that may contribute to an increase in the incidence of related complications or mortality? This retrospective review of data attempted to answer the above concern., Methods: Between January 1, 1998, and June 30, 1999, 177 patients with ejection fractions of 30% or less underwent full sternotomy coronary artery bypass grafting at our institution. Of these patients, 45 underwent OPCAB procedures and 132 patients underwent CCAB. Pre-, intra-, and postoperative variables as identified by The Society of Thoracic Surgeons National Cardiac Surgery Database were compared using univariate and logistical regression analysis., Results: Despite recognized hemodynamic derangement during cardiac displacement, these groups of OPCAB patients appeared to tolerate the procedure well. Univariate analysis of cardiac enzyme leak and blood loss was statistically significant in the OPCAB patients. Utilizing regression analysis, cardiopulmonary bypass was the only predictor for all postoperative complications., Conclusions: Multivessel coronary artery bypass utilizing the OPCAB approach in patients with depressed left ventricular function of equal to or less than 30% is appropriate and applicable. Analysis of CCAB and OPCAB variables was nonsignificant except for operative and postoperative blood loss and peak cardiac enzyme leak. Attention to intraoperative detail and hemodynamic management could be credited for the success with OPCAB.

Background: Off-pump coronary artery bypass (OPCAB) is an emerging procedure. It is assumed that elimination of cardiopulmonary bypass for coronary artery bypass grafting has the potential for reducing postoperative morbidity. This review evaluates the safety and impact of multivessel OPCABG as compared to CABG., Methods: A retrospective review of 744 patients undergoing multivessel coronary artery bypass between January 1, 1997, and March 31, 1999, was done. The total population was divided into two groups: group A (n = 609 cardiopulmonary bypass) and group B (n = 135 OPCAB). This consecutive study cohort was elective status, full sternotomy with three or more distal anastomoses performed at a single institution., Results: The mean risk adjusted predicted mortality was 2.3% in group A and 2.7% in group B (p = NS), with the mean number of distal anastomosis being greater in group A (3.8 vs 3.5/patient, p < 0.001). Major postoperative complications were similar but were not statistically significant between groups. Postoperative blood loss and use of blood transfusions were the only significant variables (p < 0.001)., Conclusions: Multivessel OPCABG can be safely performed in selected patients. Elimination of cardiopulmonary bypass did not significantly reduce postoperative morbidity. Prospective randomized trials and long-term follow-up are needed to better define patient selection and the role of OPCABG.

Background: We evaluated the application of the off-pump coronary artery bypass (OPCAB) procedure relative to safety and efficiency as measured by operative mortality postoperative complications and longitudinal outcome., Methods: Three hundred and fifty OPCAB patients were compared to 3,171 on-pump or conventional coronary artery bypass (CCAB) patients between January 1, 1997 and December 31, 1998. The groups were divided into three preoperative predicted risk categories: low-risk (0 to 2.59%), medium-risk (2.6 to 9.9%), and high-risk (> or =10%). Society of Thoracic Surgeons National Cardiac Surgery Database definitions and predicted risk group models were utilized to compare all preoperative, intraoperative, and postoperative variables using univariate analysis., Results: Overall comparison of the immediate outcome of CCAB and OPCAB shows little statistical significance in the variables analyzed. The operative mortality was 3.4% in both groups. When the immediate outcome was compared between groups (CCAB vs OPCAB), as well as individual risk groups (low, medium, and high), similar patterns of operative variables and postoperative complications were observed. The operative mortality in the low-risk group was 1.1% for CCAB and 1.4% for OPCAB; 7% for CCAB and 6% for OPCAB in the medium-risk group; and in the high-risk group 28.5% for CCAB compared to 7.7% for OPCAB group (p = 0.008). Short-term follow-up shows a trend of increased recurring angina and reinterventional procedures in the OPCAB patients., Conclusions: Safety for OPCAB is assessed through retrospective data review. Longitudinal follow-up for survival, reintervention, and quality of postoperative document efficacy and patency rates, compared to on-pump procedures, is mandatory. This study documented the immediate safety of the OPCAB procedure. Preliminary findings at 1-year follow-up is an important finding in this study, but it is not conclusive at this time. Long-term longitudinal follow-up is required to assess the future effectiveness of OPCAB.

Ouabain, a specific inhibitor of the sodium- and potassium-activated adenosine triphosphatase, causes reversible inhibition of the fusion of myoblasts to form myotubes. We further examined this observation to investigate whether control of Na/K-ATPase activity may normally contribute to the regulation of myogenesis. In control cultures, fusion was preceded by a small decrease in intracellular sodium concentration, but intracellular sodium and potassium increased significantly during fusion. Levels of ouabain that produce prolonged inhibition of fusion (400 microM) virtually eliminated sodium and potassium gradients. However, lower ouabain levels (10-100 microM) also produced significant changes in intracellular potassium and/or sodium along with little apparent decrease in the eventual extent of fusion. The effect of ouabain on protein synthesis was also examined. Low levels of ouabain (<50 microM) that did not affect myogenesis also did not affect incorporation of radiolabeled amino acids, while higher concentrations produced a decline in protein synthesis that paralleled decreases in the rate of myoblast fusion. Levels of metabolic labeling were reduced 90% in cultures treated with 400 microM ouabain. Inhibition of protein synthesis would prevent membrane remodeling required for fusion and other events in myogenesis. Thus, our results do not support any specific role for the sodium- and potassium-activated adenosine triphosphatase in regulating myogenesis.

Background: Coronary artery bypass grafting without cardiopulmonary bypass is gaining popularity as an alternative to conventional on-pump technique for myocardial revascularization. This includes minimally invasive direct coronary artery bypass (MIDCAB) and full sternotomy off-pump (OPCAB) methods. These two approaches should be evaluated for financial and clinical appropriateness., Methods: Records of patients who had single or double bypass (internal mammary artery and/or saphenous vein) grafts between January 1997 and June 1998 were reviewed. These included 44 MIDCAB, 62 OPCAB, and 243 conventional coronary artery bypass (CCAB) patients. Univariate analysis was applied to pre, intra, and postoperative variables, comparing MIDCAB and OPCAB to the CCAB group. Procedural cost information was obtained from participating institutions., Results: MIDCAB patients compared to CCAB patients had a higher predicted risk (5.4+/-11 versus 2.3+/-2.8, p = 0.012) and OPCAB patients had a predicted risk of 5.3+/-7.8. MIDCAB and OPCAB procedures required less operating room time and blood utilization. Observed operative mortality rates were MIDCAB 4.5%, OPCAB 1.6%, and CCAB 2.8% (not significant). Mean hospital costs were CCAB at $19,000, OPCAB at $15,000, and $17,000 for MIDCAB., Conclusions: Off pump procedures currently reflect acute episode-of-care cost savings over CCAB.

Background: In 1993, the Minnesota Society of Thoracic Surgeons and the Minnesota Cardiac Surgery Database were organized in response to a third-party payer demand for data about practice protocols and patient outcomes. It has matured to an active organization of 46 cardiothoracic surgeons, 14 institutions, and more than 7,000 patients who have undergone coronary artery bypass grafting., Methods: Data are validated for completeness and accuracy through a statewide auditing process. They are coded by hospital, analyzed using the standard Society of Thoracic Surgeons National Cardiac Surgery Database format and definitions, and reviewed quarterly in a continuous quality improvement process., Results: Through data review and exchange site visits, variations in practice protocols and outcomes have been identified. For example, our statewide data review and continuous quality improvement process identified prolonged ventilation (more than 24 hours) as one variation. Multidisciplinary teams were defined, and statewide exchange site visits led by cardiovascular surgeons were implemented. An example of the improvement in the accuracy and completeness of the data used to study procedure outcomes is represented by the improved reporting of ejection fraction values that has resulted from this process., Conclusions: Using the standardized Society of Thoracic Surgeons National Cardiac Surgery Database and the Minnesota Society of Thoracic Surgeons organizational structure to establish a high-quality database will allow for statewide peer review, exchange of practice guidelines, and promotion of standardization, which eventually can improve outcomes and reduce costs. This organization or model can be replicated at any local, state, or regional level. Thoracic surgeons faced with similar challenges for public disclosure of surgical results can learn much from the successful development of the Minnesota Cardiac Surgery Database.

Background: This study examined the efficacy and safety of retrograde cardioplegia in comparison with an antegrade/retrograde approach., Methods: Between January 1, 1991, and December 31, 1995, 7,032 coronary artery bypass procedures, alone or in combination with valve replacement/repair, were performed using either retrograde cardioplegia (R) or an antegrade/retrograde (AR) approach. There were 4,224 patients in the R group and 2,808 in the AR group. These included elective, urgent, emergent/salvage, first operative, and redo cases., Results: All preoperative, intraoperative, and postoperative variables listed in The Society of Thoracic Surgeons National Cardiac Surgery Database were used to compare the two groups using univariate analysis. The pump time was longer in the AR group, with fewer grafts per patient. The R group had higher predicted risk (3.2% versus 3.0%; p = 0.04), more postoperative atrial fibrillation (34% versus 31%; p = 0.006), and longer postoperative length of stay (8.8 versus 8.0 days; p < 0.001). Using The Society of Thoracic Surgeons National Cardiac Surgery Database predicted risk group model, a subgroup of 221 coronary artery bypass grafting patients in the retrograde (s-R) and 132 coronary artery bypass grafting patients in the antegrade/retrograde (s-AR) group fell into a greater incidence of predicted mortality group (> or = 10%). The s-R subgroup had more patients in New York Heart Association functional class IV. Univariate analysis revealed higher postoperative atrial fibrillation (51% versus 41%; p = 0.05) and longer postoperative length of stay (12.8 versus 10.8 days; p = 0.03) in the s-R subgroup versus the s-AR subgroup., Conclusions: The results appear to favor neither approach. Preoperatively, both retrograde groups (R and s-R) had higher preoperative predicted risk, but operative mortality or complications were not significantly increased when compared with the AR and s-AR groups. Retrograde cardioplegia alone was shown to be effective in the R and s-R groups, but atrial fibrillation developed in more patients, which could have contributed to longer length of stay in these groups. Antegrade/retrograde cardioplegia offers good immediate outcome but the delivery method can be cumbersome and confusing during the adjustments of flow clamps for antegrade/retrograde delivery and may contribute to prolonged pump times. From this retrospective, nonrandomized review, it appears that retrograde cardioplegia alone provides as good myocardial protection and safety as an antegrade/retrograde approach in either the low-risk or high-risk patient.

Background and Aims of the Study: This communication reports the anticoagulant-related complications (ARH) in patients who received the St. Jude Medical mechanical prosthesis and were 70 years of age or older at the time of implantation., Methods: Our institutional data file shows that during the 15-year period from 1977 to 1992, our group implanted the St. Jude Medical mechanical prosthesis in 610 patients with aortic valve disease (AVR) and 186 patients with mitral disease (MVR), who were 70 years or older, either with or without coronary artery bypass grafts. The operative mortality was 6.4% for AVR and 16% for MVR. The mean follow up for this elderly group was 4.9 years (2,996 patient-years) for AVR and 4.2 years (771 patient-years) for MVR., Results: The incidence of late death was 30% for AVR and 33% for MVR. The freedom from TE was 91.6% +/- 1.8%, from valve thrombosis 98.8% +/- 0.7%, and from ARH 95.9% +/- 1.1%. The freedom from operative death, valve-related death, and all complications was 78.8% +/- 2.4%. The data from this study shows that both the aortic and the mitral valve replacement patients who were 70 years or older have an acceptable rate of bleeding complications. Reduction of the intensity of anticoagulation in our practice (INR of 1.8-2.5 for AVR and 2.5-3.2 for MVR) may play a role in this finding. The incidence of valve thrombosis and TE rates were also low in this study., Conclusions: With increasing life expectancy in the elderly, the use of the St. Jude Medical Mechanical prosthesis and low intensity anticoagulation could be reconsidered for a selected group of elderly patients.

Background: The Perma-Flow prosthetic coronary graft is a 5-mm polytetrafluoroethylene tube into which is incorporated a Venturi flow restrictor. An aorto-superior vena caval fistula is created and coronary anastomoses are constructed proximal to the resistor in side-to-side fashion, where arterial pressure is maintained. From November 1992 through December 1995, eight investigational centers in North America have implanted this graft in 40 patients with inadequate autologous alternatives., Methods: Patients were selected for inclusion in this study if coronary artery bypass grafting was required and adequate autologous conduit to complete revascularization was not available. Operative data were completed by the implantating surgeon and referred to a central center, the Minneapolis Heart Institute, for correlation. Follow-up was conducted by data coordinators at each institution, and follow-up data were obtained directly from these coordinators for inclusion in the study., Results: Patient age ranged from 53 to 82 years, and 15 patients were undergoing reoperations (38%). On each Perma-Flow graft one to four coronary side-to-side anastomoses were constructed. In addition, left internal mammary artery (n = 26), greater saphenous vein (8), right internal mammary artery (4), and gastroepiploic artery (4) were used to complete revascularization. Aortic (2) or mitral valve replacement (1) was also carried out. There were seven operative deaths (18%) and two late deaths (4 and 6 months). After 1 to 37 months (mean, 13 +/- 9 months) of follow-up, 29 of 31 surviving patients are asymptomatic. Echocardiographic heart size has not increased from the postoperative value, indicating limited volume load has not affected heart size. Protocol catheterization (n = 32) in 28 patients 1 week to 1 year postoperatively revealed 7 of 73 studied coronary anastomoses (9.5%) and two distal extensions and resistors were occluded (7%). In 1 patient during sternal debridement at 1 year, no flow was found in the graft., Conclusions: The Perma-Flow graft is a useful adjunct to complete revascularization in patients with deficient autologous conduit.

Background: The move toward outpatient and same-day surgery has been phenomenal in the past several years. Efforts in this area have focused on limiting inpatient hospitalization, reducing ancillary services, and decreasing length of stay., Methods: Two hundred seventy-six DRG 107 patients who were operated on at our institutions in 1994 and registered in The Society of Thoracic Surgeons National Cardiac Surgery Database were reviewed. There were 185 patients randomly admitted to the hospital on the day of operation and 91 patients admitted 1.78 +/- 1.94 days before. These patients were analyzed according to The Society of Thoracic Surgeons National Cardiac Surgery Database predicted risk group and expected operative mortality modules. Univariate analysis of all risk variables listed in The Society of Thoracic Surgeons National Cardiac Surgery Database were used to identify the difference between 176 elective procedure patients in the same-day admission group and 67 elective procedure patients in the non-same-day admission group., Results: The same-day admission group had lower expected operative mortality (1.3% versus 2.9%), fewer female patients (17% versus 29%), younger age (62 versus 67 years), and fewer patients in the higher predicted risk group. Univariate analysis showed only age and ejection fraction variables were significantly different between the two elective groups. Comorbidities predictive of elective non-same-day admission revealed that age and New York Heart Association class IV were significant predictors. The length of stay was shorter and the total charges were less in the same-day admission group., Conclusions: There was no increase in preoperative, intraoperative, or postoperative complications in the same-day admission patients. Same-day admission was safe and cost-effective and could be carried out as a routine admission for several selected groups of patients.

Background: The St. Jude Medical prosthesis has become the most commonly used artificial heart valve, yet few data are available in the pediatric population. This study addresses results of the use of this prosthetic valve in pediatric patients over a 13-year time frame., Methods: From January 1982 through June 1994, 73 patients (49 male) underwent 75 valve replacements using the St. Jude Medical prosthesis at Minneapolis Children's Medical Center. Follow-up was complete in 71 patients, with a mean follow-up of 39 +/- 32 months (mean +/- standard deviation; range, 4 to 142 months)., Results: Valves' positions were aortic in 36 patients, mitral or left atrioventricular valve in 34, tricuspid in 1, and double valve in 2. Patient age was 8 +/- 6 years, with a range of 1 week to 19 years. Sixteen patients were less than 24 months of age at valve replacement. Prior cardiac procedures had been performed in 82% of mitral patients, 58% of aortic patients, and all of the tricuspid and double-valve patients. Elective valve replacement was performed in 62 to 73 patients (85%). Seven patients (44%) less than 24 months of age had urgent valve replacement; 4 patients (7%) older than 24 months required urgent valve replacement. Overall early mortality was 8% (6 of 73); 36% (4 of 11) in the patients undergoing urgent valve replacement and 3% (2 of 62) in the elective group. All but one of the deaths were due to cardiac dysfunction. There were four late deaths, from 4 to 125 months postoperative, primarily caused by congestive heart failure or pulmonary vascular disease. Cumulative freedom from valve-related events was 93%, 85%, and 77% at 1, 5, and 10 years, respectively. Valve-related complications included thromboembolism (4), bleeding (5), perivalvar leak requiring reoperation (2), transient ischemic attack (1), and endocarditis (1). There have been no permanent strokes or mechanical malfunction. The majority of patients are currently managed with warfarin. Five surviving patients whose initial valve replacement was at age 24 months or younger have undergone repeat valve replacement (42%). Ninety-five percent of patients enjoy good health at follow-up., Conclusions: The St. Jude Medical prosthesis offers correction of valvular disease with low morbidity and mortality, and excellent functional result.

Background: This study examined predictors and cost-effectiveness of early extubation after coronary artery bypass grafting., Methods: Six hundred forty-five patients admitted to intensive care units after coronary artery bypass grafting at our institutions in 1993 were reviewed. There were 455 male and 190 female patients, which included all patients in DRG 106 and DRG 107. The patients were categorized into three groups: group A (269 patients) were extubated in less than 12 hours (7.55 +/- 2.5 hours), group B (291 patients) were extubated between 12 and 24 hours (16.85 +/- 3.3 hours), and group C (376 patients) were extubated any time after 12 hours., Results: The reintubation rate for the entire group was less than 1%. Univariate preoperative analyses revealed small differences between groups A and B: only 6 of 25 variables were found to reach statistical significance. Stepwise logistic regression analyses were carried out in 269 patients of group A and 376 patients of group C. Older patients (log of age, p = 0.0001), female sex (p = 0.0129; odds ratio = 1.634), use of preoperative diuretics (p = 0.0010; odds ratio = 1.965) and unstable angina (p = 0.0301; odds ratio = 1.544) were noted to be clinical factors associated with late extubation (> or = 12 hours). Early extubation was accomplished in 42%; however, further analysis revealed that many patients who were intubated overnight should have been extubated sooner., Conclusions: Early extubation shortened the postoperative length of stay, resulting in reduction of cost and resource utilization. The average hospital charge per patient was approximately $6,000 less in the early extubation group.

The records of 94 patients with a known diagnosis of extrahepatic cancer having liver scan, biochemical liver tests (alkaline phosphatase, SGOT, lactic dehydrogenase, and bilirubin levels, and subsequent liver biopsy within a six-week period were reviewed. The sensitivity, specificity, and accuracy of the scan and biochemical tests in the detection of metastatic liver disease were calculated. The most sensitive single examination was the group of biochemical liver tests. Liver scans performed in the presence of normal biochemical test results were insensitive when compared with the liver scan alone or the liver scan in the presence of abnormal biochemical test results. The specificity and accuracy of all tests and test combinations were statistically equivalent. Screening for hepatic metastases in patients with cancer is best accomplished with the more sensitive and less expensive group of biochemical liver tests, reserving the liver scan for those patients with abnormal biochemical test results.

During 1985, low-level radioactive waste disposal has become a critical concern. The issue has been forced by the threatened closure of the three commercial disposal sites. The medical community has used radioactive isotopes for decades in nuclear medicine, radiation therapy, radioimmunoassay, and biomedical research. Loss of disposal capacity for radioactive wastes generated by these activities, by the suppliers of radioisotopes, and by pharmaceutical companies will have a profound impact on the medical profession.

The effect of acetaminophen on the labeling efficiency of leukocytes with indium oxine In 111 was studied. A blood sample was obtained from eight healthy men before and after they received acetaminophen 650 mg every four hours for 24 hours. After dividing the plasma from each sample into three portions, leukocytes were separated and labeled with indium oxine In 111. In an in vitro study, 200 ml of blood was obtained from one of the men, and the plasma was separated into four portions. Acetaminophen in 95% ethanol was added to three of the plasma fractions to produce acetaminophen concentrations of 4, 20, and 100 micrograms/ml; ethanol was added to the fourth fraction as a control. Each plasma fraction was then subdivided into three aliquots, and leukocytes were labeled as in the in vivo study. Mean leukocyte labeling efficiencies in both studies were calculated from the ratios of leukocyte radioactivity to initial radioactivity in the samples, expressed as percentages. Leukocyte labeling efficiencies before acetaminophen administration ranged from 79 to 85%; after administration, labeling efficiencies ranged from 70 to 87%. No significant differences in mean labeling efficiency before and after acetaminophen administration were noted in any of the subjects. Leukocyte labeling efficiencies in all in vitro plasma fractions were reduced, ranging from 54 to 63%, but no significant differences in labeling efficiency between any of the plasma fractions were found. Using the labeling procedures in this study, exposure of leukocytes from healthy men to acetaminophen in vivo or in vitro does not affect labeling efficiency with indium oxine In 111.

The use of In-111 labeled leukocytes for abscess localization is becoming well established. The first report of In-111 imaging following hepatic embolization is presented. A 45-year-old man with adenocarcinoma of the colon and metastatic liver disease was treated for intractable pain using particulate embolization of the hepatic artery. In-111 leukocyte imaging was performed to rule out abscess formation. The distribution of the labeled leukocytes demonstrated hepatic uptake commensurate with Tc-99m sulfur colloid (SC) images. Areas of embolization did not accumulate tracer. Pathologic examination at autopsy correlated with the distribution of the labeled leukocytes. Thus, therapeutic embolization did not alter the normal distribution of this tracer in functional hepatic tissue.

A novel fluoropolymer prepared from ethylcellulose by acylation with perfluorobutyryl chloride has been shown to be remarkably non-thrombogenic in vena cava and renal embolus ring implant tests. Gas permeabilities of this fluoropolymer are dufficient to make it highly attractive for membrane blood oxygenators, either in the form of a thin film supported by a porous substrate or as a thin coating deposited onto microporous substrates. The broad solvent solubility of this fluoropolymer allows it to be fabricated into membranes by pratical processes. Good adhesion of coatings of this polymer to rigid and semi-rigid plastic surfaces can be achieved in many cases. This fluoropolymer represents an important new biomaterial for use in blood handling and oxygenation devices.

This study examined the hypothesis that the type of list context in which a given item is embedded may affect the way in which it is perceptually processed. In the first experiment, subjects matched four types of test items inserted in four types of lists. The types of test items and the types of lists in which they were embedded were two-letter words, two-letter spelling clusters, unrelated letter pairs, and pairs of novel letters. The first experiment indicated that only unrelated letter pairs were significantly affected by type of list in which they were inserted. The pattern of the effect was confirmed in the latency data of the second experiment and the interpretation was that only unrelated letter and related letter-group contexts were operating in the first two experiments. The third and fourth experiments were concerned with contrasting contexts at the feature and letter levels of processing. By using lists in which type of catch trial either emphasized local features or global aspects of a pattern, the processing times of both familiar and unfamiliar letters were affected. The results of these experiments suggest that information processing models should incorporate structures which represent the way that context selectively facilitates processing of items at particular levels.