Relationship among aqueous copper half-lives and responses of Pimephales promelas to a series of copper sulfate pentahydrate concentrations.

Copper algaecide exposures in situ are often of shorter duration than exposures for static toxicity experiments because aqueous concentrations in situ dissipate as a function of site-specific fate processes. Consequently, responses of organisms to static copper exposures may overestimate effects following in situ exposures. To understand the role of exposure duration for altering responses, Pimephales promelas survival was compared following static (96 h) and pulse (1.

Cell density dependence of Microcystis aeruginosa responses to copper algaecide concentrations: Implications for microcystin-LR release.

Along with mechanistic models, predictions of exposure-response relationships for copper are often derived from laboratory toxicity experiments with standardized experimental exposures and conditions. For predictions of copper toxicity to algae, cell density is a critical factor often overlooked. For pulse exposures of copper-based algaecides in aquatic systems, cell density can significantly influence copper sorbed by the algal population, and consequent responses.

Influence of CuSO and chelated copper algaecide exposures on biodegradation of microcystin-LR.

Copper exposures from algaecide applications in aquatic systems are hypothesized to impede bacterial degradation of microcystin (MC), a cyanobacterial produced hepatotoxin. Despite regulatory implications of this hypothesis, limited data exist on influences of copper-exposures on MC-degrading bacteria and consequent MC-degradation. In this study, influences of copper-algaecide concentrations and formulations on bacterial composition and microcystin-LR (MCLR) degradation were investigated.

A risk-based approach for identifying constituents of concern in oil sands process-affected water from the Athabasca Oil Sands region.

Mining leases in the Athabasca Oil Sands (AOS) region produce large volumes of oil sands process-affected water (OSPW) containing constituents that limit beneficial uses and discharge into receiving systems. The aim of this research is to identify constituents of concern (COCs) in OSPW sourced from an active settling basin with the goal of providing a sound rational for developing mitigation strategies for using constructed treatment wetlands for COCs contained in OSPW. COCs were identified through several lines of evidence: 1) chemical and physical characterization of OSPW and comparisons with numeric water quality guidelines and toxicity endpoints, 2) measuring toxicity of OSPW using a taxonomic range of sentinel organisms (i.

Influence of commercial (Fluka) naphthenic acids on acid volatile sulfide (AVS) production and divalent metal precipitation.

Energy-derived waters containing naphthenic acids (NAs) are complex mixtures often comprising a suite of potentially problematic constituents (e.g. organics, metals, and metalloids) that need treatment prior to beneficial use, including release to receiving aquatic systems.

Effects of environmental conditions on aerobic degradation of a commercial naphthenic acid.

Naphthenic acids (NAs) are problematic constituents in energy-derived waters, and aerobic degradation may provide a strategy for mitigating risks to aquatic organisms. The overall objective of this study was to determine the influence of concentrations of N (as ammonia) and P (as phosphate), and DO, as well as pH and temperatures on degradation of a commercial NA in bench-scale reactors. Commercial NAs provided replicable compounds necessary to compare influences of environmental conditions on degradation.

Comparative toxicity of sodium carbonate peroxyhydrate to freshwater organisms.

Sodium carbonate peroxyhydrate (SCP) is a granular algaecide containing H2O2 as an active ingredient to control growth of noxious algae. Measurements of sensitivities of target and non-target species to hydrogen peroxide are necessary for water resource managers to make informed decisions and minimize risks for non-target species when treating noxious algae. The objective of this study was to measure and compare responses among a target noxious alga (cyanobacterium Microcystis aeruginosa) and non-target organisms including a eukaryotic alga (chlorophyte Pseudokirchneriella subcapitata), microcrustacean (Ceriodaphnia dubia), benthic amphipod (Hyalella azteca), and fathead minnow (Pimephales promelas) to exposures of hydrogen peroxide as SCP.

Comparative responses of freshwater organisms to exposures of a commercial naphthenic acid.

Comparative toxicity studies using unconfounded exposures can prioritize the selection of sensitive sentinel test species and refine methods for evaluating ecological risks of complex mixtures like naphthenic acids (NAs), a group of organic acids associated with crude oils and energy-derived waters that have been a source of aquatic toxicity. The objectives of this study were to compare responses of freshwater aquatic organisms (vertebrate, invertebrates, and a macrophyte; in terms of acute toxicity) to Fluka commercial NAs and to compare measured toxicity data with peer-reviewed toxicity data for other commercial NA sources and energy-derived NA sources. Exposures were confirmed using high performance liquid chromatography.

Responses of Lyngbya wollei to algaecide exposures and a risk characterization associated with their use.

To make informed decisions regarding management of noxious algal growths, water resource managers require information on responses of target and non-target species to algaecide exposures. Periodic treatments of Phycomycin®-SCP (sodium carbonate peroxyhydrate) followed by Algimycin®-PWF (gluconate and citrate chelated copper) to control Lyngbya wollei growths for ten years provided an opportunity for a risk evaluation of treated coves in Lay Lake, AL. Abiotic sediment characteristics (acid soluble copper concentrations, acid volatile sulfides, percent organic matter and cation exchange capacity) and survival of Hyalella azteca and Chironomus dilutus were measured in sediment samples from treated and untreated coves to assess the bioavailability of potential copper-residuals.

Opening the pleura during internal mammary artery harvesting: advantages and disadvantages.

Objective: To evaluate the findings of previous studies that opening of the pleura during internal mammary artery (IMA) dissection might be an important factor in increasing the operative morbidity.

Design: A randomized control trial.

Setting: A university hospital.

Evidence of type 2 herpes simplex infection in human coronary arteries at the time of coronary artery bypass surgery.

Objective: To examine histologically biopsies from the coronary arteries of patients undergoing coronary artery bypass grafting (CABG) for evidence of herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2) antigen and to correlate the incidence with pathological and clinical data.

Design: Sequential patients undergoing CABG in whom adequate tissue could be obtained for histology.

Setting: University teaching hospital.

Optimal imaging techniques for locating leaflets after escape from prosthetic heart valves.

The authors report two cases of leaflets escaping from an Edwards-Duromedics bileaflet prosthetic heart valve (Baxter-Edwards Division, Baxter Healthcare Corp., Irvine, Calif.).

The safety of intermittent warm blood cardioplegia.

Continuous warm blood cardioplegia is considered to be an effective method for myocardial protection. However, frequently the flow of the cardioplegia needs to be interrupted for better visualization. Intermittent warm blood cardioplegia was reported to be safe by some investigators.

The measurement of afterload, vascular input impedance, and power distribution in aorto-femoral bypass.

The effects of aorto-femoral bypass grafts on the vascular input impedance, and the ratio of pulsatile to total power were studied in eight dogs. Unilateral ileo-femoral stenosis was simulated and comparisons were made between the input impedance and power distribution in healthy and simulated disease situations. Input impedance magnitude spectra and phase were displayed graphically and it was shown that the presence of the simulated disease increases the ratio of pulsatile to total power as measured in the abdominal aorta from 7.

Prevention of neurological injury during myocardial revascularization in patients with calcific degenerative aortic disease.

Neurological injury following myocardial revascularization may result from embolization of atheromatous debris from the diseased ascending thoracic aorta. Eight patients with calcified aortas who underwent elective myocardial revascularization suffered major strokes as a result of manipulation and clamping of the diseased ascending aorta during a 30-month period before July, 1981. computerized axial tomography scans demonstrated multiple cerebral infarctions in each patient.

Myocardial metabolism and hemodynamic responses with isoflurane anesthesia for coronary arterial surgery.

Isoflurane-oxygen was given for induction and maintenance of anesthesia to ten patients having coronary artery bypass grafts. All had preserved ventricular function without hypertension or other cardiac lesions; treatment with beta-blocking drugs was maintained until the operation in all patients. Cardiac output, arterial and central pressures, coronary sinus (CS) blood flow, arterial and CS oxygen, Hb, and lactate contents were measured before, six times during, and twice after anesthesia.

Myocardial metabolism and hemodynamic responses with fentanyl-enflurane anesthesia for coronary arterial surgery.

Ten patients for coronary vein grafting had induction of anesthesia with fentanyl (30 micrograms/kg), followed by enflurane-oxygen sufficient to decrease systolic blood pressure by 27% before intubation. Enflurane was continued in concentrations to maintain blood pressure below that with patients awake. All patients had preserved ventricular function and effective beta-blockade.

Simulation of coronary artery revascularization.

Simulation of the commonly constructed geometries of aorto-coronary bypass anastomoses was carried out using especially fabricated distensible tubes and a pulsatile pump. The system pressure was maintained between 80 and 120 mmHg. The total mean flow was set at 250 ml min-1 (Reynolds number of 200) and the pulsatile frequency was varied from 0 to 2 Hz.

Intimal hyperplasia in autogenous vein grafts used for arterial bypass: a canine model.

Late vein graft occlusion following myocardial revascularisation is usually the result of progressive intimal hyperplasia which ultimately leads to vein graft thrombosis. Considerable attention has recently been directed towards the development of optimal platelet-inhibiting drug regimens designed to prevent intimal hyperplasia in autogenous vein grafts. This report describes an animal model that reliably reproduces short-term intimal hyperplasia in autogenous vein grafts, thus facilitating the study of platelet-inhibiting drug regimens for the prevention of intimal hyperplasia.

Cod-liver oil in the prevention of intimal hyperplasia in autogenous vein grafts used for arterial bypass.

Cod-liver oil, rich in eicosapentaenoic acid, an unsaturated fatty acid, was administered to 14 mongrel dogs to determine if this acid would prevent platelet-mediated intimal hyperplasia. Twenty-eight 1 cm segments of undistended jugular vein were interposed between bilaterally divided femoral arteries. Seven control animals were fed a 2% cholesterol diet 1 week before and for 6 weeks after the operation.

Encircling endocardial resection with complete removal of endocardial scar without intraoperative mapping for the ablation of drug-resistant ventricular tachycardia.

Encircling endocardial resection, with complete removal of endocardial scar unguided by intraoperative mapping, was employed in 10 patients with drug-resistant sustained ventricular tachycardia. Reproducible sustained ventricular tachycardia was induced in all patients preoperatively with programmed electrical stimulation. A trial of conventional antiarrhythmics had failed in all 10 patients; seven patients required frequent cardioversion, and three patients required overdrive suppression with temporary transvenous pacing.

The effects of nitrous oxide on myocardial metabolism and hemodynamics during fentanyl or enflurane anesthesia in patients with coronary disease.

Twenty patients about to have coronary artery bypass grafts were studied before and after 15 min of 50% nitrous oxide added to either fentanyl (75 micrograms/kg) or enflurane (0.5%) anesthesia. Arterial and central pressures and cardiac output were measured, plus coronary sinus blood flow and arterio-coronary sinus differences in oxygen, hemoglobin, and lactate contents.

Myocardial metabolism and haemodynamic responses during high-dose fentanyl anaesthesia for coronary patients.

Fentanyl (mean dose 109 micrograms X kg-1) and oxygen were given to ten patients having coronary vein grafts. Serial studies were done before, during and after operation, of central and mean arterial pressures (MAP), cardiac index (CI) and coronary sinus flow (CBF) by thermodilution, myocardial oxygen consumption (MVO2) and lactate extraction (MLE). On induction CI and stroke work index decreased, but heart rate and MAP were unchanged as systemic resistance increased.

Myocardial metabolism and haemodynamic responses with enflurane anaesthesia for coronary artery surgery.

Ten patients were studied before, during and after enflurane anaesthesia for coronary vein grafting. All had good ventricular function and nine were receiving effective beta blockade. Cardiac output and vascular pressures were measured, plus coronary sinus blood flow (CBF), myocardial oxygen consumption (MVO2) and lactate extraction (MLE).