Characterizing grassland fire activity in the Flint Hills region and air quality using satellite and routine surface monitor data.

Prescribed grassland fires in the Flint Hills region of central Kansas and northern Oklahoma are a common tool for land management. Local to regional scale impacts on air quality from grassland fires in this region are not well understood, which is important as these types of prescribed fires may increase in the future to preserve broader areas of native grasses in the central U.S. Routine air quality and deposition measurements from sites in and near the Flint Hills were examined for coincident increases during periods of increased prescribed grassland fires. Prescribed fire activity in this region was quantified using satellite detections and multiple publicly available data products of area burned information. March and April comprise over half (41 to 93%) of all annual fire detections in the Flint Hills region seen from satellites between 2007 and 2018 excluding drought years. Annual total fire detections in this region range between 1 and 12 thousand and account for approximately 3% of all fire detections in the contiguous U.S. Annual acres burned ranged from 0.2 to 2 million acres based on U.S. EPA's National Emission Inventory, which accounts for 4 to 38% of grasslands in the area. A comparison of weekly standardized anomalies suggests a relationship between periods of increased grassland fire activity and elevated levels of PM2.5 organic carbon, elemental carbon, and potassium. Daily 1-hr maximum ozone (O3), ammonia (NH3), sulfur dioxide (SO2), and oxidized nitrogen gases measured at Konza Prairie also had increased levels when prescribed grassland fire activity was highest. This detailed characterization of prescribed fire activity in the Flint Hills and associated air quality impacts will benefit future efforts to understand changes in atmospheric composition due to changing land management practices.

Photochemical model evaluation of 2013 California wild fire air quality impacts using surface, aircraft, and satellite data.

The Rim Fire was one of the largest wildfires in California history, burning over 250,000 acres during August and September 2013 affecting air quality locally and regionally in the western U.S. Routine surface monitors, remotely sensed data, and aircraft based measurements were used to assess how well the Community Multiscale Air Quality (CMAQ) photochemical grid model applied at 4 and 12 km resolution represented regional plume transport and chemical evolution during this extreme wildland fire episode. Impacts were generally similar at both grid resolutions although notable differences were seen in some secondary pollutants (e.g., formaldehyde and peroxyacyl nitrate) near the Rim fire. The modeling system does well at capturing near-fire to regional scale smoke plume transport compared to remotely sensed aerosol optical depth (AOD) and aircraft transect measurements. Plume rise for the Rim fire was well characterized as the modeled plume top was consistent with remotely sensed data and the altitude of aircraft measurements, which were typically made at the top edge of the plume. Aircraft-based lidar suggests O3 downwind in the Rim fire plume was vertically stratified and tended to be higher at the plume top, while CMAQ estimated a more uniformly mixed column of O3. Predicted wildfire ozone (O3) was overestimated both at the plume top and at nearby rural and urban surface monitors. Photolysis rates were well characterized by the model compared with aircraft measurements meaning aerosol attenuation was reasonably estimated and unlikely contributing to O3 overestimates at the top of the plume. Organic carbon was underestimated close to the Rim fire compared to aircraft data, but was consistent with nearby surface measurements. Periods of elevated surface PM2.5 at rural monitors near the Rim fire were not usually coincident with elevated O3.

Natural history of arrhythmogenic right ventricular cardiomyopathy in the boxer dog: a prospective study.

BACKGROUND: Boxer arrhythmogenic right ventricular cardiomyopathy (ARVC) is a disease that may result in sudden death or heart failure. HYPOTHESIS/OBJECTIVES: To prospectively study the natural history of Boxer ARVC. ANIMALS: 72 dogs (49 ARVC, 23 controls). METHODS: Boxers >1 year of age were recruited for annual reevaluation. CONTROLS were defined as being ≥6 years of age and having <50 ventricular premature complex (VPCs)/24 h. ARVC was defined as ≥300 VPCs/24 h in the absence of other disease. Dogs were genotyped for the striatin deletion when possible. Descriptive statistics were determined for age; VPC number; annual change in VPC number; and left ventricular (LV) echocardiographic dimensions. Survival time was calculated. RESULTS: Controls: median age of 7 years (range, 6-10); number of VPCs 12 (range, 4-32). Median time in study of 6 years (range, 2-9). Seventeen of 23 were genotyped (5 positive, 12 negative). ARVC: median age of diagnosis of 6 (range, 1-11). Median time in study 5 years (range, 3-8). A total of 33% were syncopal and 43/49 were genotyped (36 positive, 7 negative). Yearly change in VPCs was 46 (range, -7,699 to 33,524). Annual percentage change in LV dimensions was 0, and change in fractional shortening (FS%) was 2%. Two dogs had FS% <20%. Although ARVC dogs died suddenly, there was no difference in survival time between groups. ARVC median age of survival was 11 years, and for controls was 10 years. CONCLUSIONS/CLINICAL IMPORTANCE: Arrhythmogenic right ventricular cardiomyopathy is a disease of middle age and frequently is associated with the striatin deletion. Syncope occurs in approximately 1/3 of affected dogs; systolic dysfunction is uncommon. The prognosis in many affected dogs is good.

Temporal variability of ventricular arrhythmias in Boxer dogs with arrhythmogenic right ventricular cardiomyopathy.

BACKGROUND: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is prevalent in the Boxer. There is little information on the temporal variability of ventricular arrhythmias within affected dogs. OBJECTIVE: To evaluate ambulatory electrocardiograms (AECG) from Boxers with ARVC for hourly variation in premature ventricular complexes (PVC) and heart rate (HR). ANIMALS: One hundred and sixty-two Boxer dogs with ARVC. METHODS: Retrospective, observational study of 1,181 AECGs collected from Boxer dogs at The Ohio State University from 1997 to 2004 was evaluated. The proportion of depolarizations that were PVCs was compared across each hour of the day, during six 4-hour periods of day, to the time after AECG application, and to the maximum and minimum HR. RESULTS: A lower proportion of PVCs was noted during early morning (midnight to 0400 hours) as compared with the morning (0800-1200 hours) and late (1600-2000 hours) afternoon (P= .012). There was no increase in PVC proportion in the 1st hour after AECG application as compared with all other hours of the day (P= .06). There was poor correlation between maximum (rho= 0.19) and minimum (rho= 0.12) HR and PVC proportion. CONCLUSIONS AND CLINICAL IMPORTANCE: The likelihood of PVC occurrence in Boxer dogs with ARVC was relatively constant throughout the day, although slightly greater during the hours of 0800-1200 and 1600-2000. A biologically important correlation with HR was not apparent. The role of autonomic activity in the modulation of electrical instability in the Boxer with ARVC requires further study.

Double chambered right ventricle in 9 cats.

BACKGROUND: Double-chambered right ventricle (DCRV) is a frequently recognized cardiac congenital abnormality in humans. It has been described in dogs and in 1 cat. However systemic description of clinical and echocardiographic features of the disease in cats is currently lacking from the veterinary literature. ANIMALS: Nine cats with DCRV are described. RESULTS: The cats ranged from 4 months to 10 years of age. Eight cats at presentation were asymptomatic and 1 cat had chylothorax. In all cases echocardiography revealed abnormal fibromuscular bundles obstructing the mid-right ventricle, dividing the chamber into 2 compartments. The proximal right ventricular compartment was markedly hypertrophied, and right atrial dilation was usually present. The mean pressure gradient measured across the stenotic area was 130 +/- 50 mm Hg. Concurrent abnormalities included a ventricular septal defect (n = 2); aortic malalignment, aortic insufficiency (n = 1); and congenital peritoneal-pericardial diaphragmatic hernia (n = 1). Two cats had systolic anterior motion of the mitral valve, one of which had concurrent left ventricular hypertrophy. Five cats have remained asymptomatic for a median period of 3.6 years (range, 3.3-5 years) and 3 cats have developed clinical signs associated with congestive heart failure (at 2, 3.3, and 9 years). One cat showed progressive lethargy and exercise intolerance and underwent partial ventriculectomy at the age of 2 years. This cat died during the operation with electromechanical dissociation. CONCLUSIONS: DCRV is a congenital cardiac abnormality that may be more common than previously recognized.

Echocardiographic assessment of the left ventricular outflow tract in the Boxer.

BACKGROUND: Soft, variable ejection murmurs are common in Boxers and are associated with increased left ventricular outflow tract (LVOT) ejection velocities. Whether these murmurs are physiologic or indicate mild aortic stenosis is controversial. Ejection velocity is impacted by LVOT area and ventricular stroke volume (SV), suggesting that these variables are pertinent to murmur development. HYPOTHESIS: Boxers with ejection murmurs have a smaller LVOT and equivalent SV indices, compared with values in dogs without murmurs. ANIMALS: Three age- and weight-matched groups of dogs--15 Boxers with soft ejection murmurs (group I); 15 Boxers without murmurs (group II); and 15 nonBoxer dogs without murmurs (group III)--were studied. METHODS: All dogs underwent 2-dimensional and Doppler echocardiographic examinations. The LVOT size at multiple levels; LVOT ejection velocity, stroke distance, and SV index; and right ventricular SV index were determined and compared by analysis of variance. RESULTS: Indexed LVOT areas in Boxer groups were not different, but were significantly smaller than those of non-Boxer dogs. Ejection velocities and stroke distances were significantly different across all groups, with group I having the highest and group III having the lowest values. Doppler SV indices (ml/m2) for group-I versus group-II Boxers were 70 +/- 16(SD) versus 62 +/- 12 for the LVOT (P = .27) and 58 +/- 12 versus 48 +/- 9 for the right ventricle (P = .14). CONCLUSIONS AND CLINICAL IMPORTANCE: These data suggest that a relatively smaller LVOT in Boxers predisposes them to increased ejection velocity and development of murmurs. The contribution of SV to the genesis of these often labile murmurs requires additional study.

Effects of platelet clumping on platelet concentrations measured by use of impedance or buffy coat analysis in dogs.

OBJECTIVE: To determine whether platelet clumps are homogeneously distributed in blood samples, and whether platelet concentrations (PC) obtained by use of impedance and buffy coat analysis can be considered minimum values when platelet clumps are present. DESIGN: Prospective study. SAMPLE POPULATION: 50 blood samples obtained from 30 dogs. PROCEDURE: 10 blood samples containing platelet clumps were used and 10 smears were made from each sample; amount of platelet clumping was graded for all 100 smears. Blood from each of 20 healthy dogs was divided between 2 EDTA tubes before and after platelet clumping was induced by adenosine diphosphate (ADP). The PC for each ADP-treated and untreated sample were measured, using impedance and quantitative buffy coat analyzers. RESULTS: Platelet clumps were evident in all 100 blood smears, but the amount of clumping varied considerably within some samples. Using the impedance analyzer, the PC of ADP-treated samples were significantly lower and never higher than the PC of untreated samples. Using the buffy coat analyzer, some ADP-treated samples had increased PC; however, significant differences were not detected between treated and untreated samples. CONCLUSIONS AND CLINICAL RELEVANCE: Platelet clumping was not homogeneous within blood samples. When platelet clumps were identified by direct examination of blood smears, the PC detected by use of the impedance analyzer could be considered minimum values. In contrast, the PC detected by use of the buffy coat analyzer were sometimes increased. Useful information can be obtained by measuring PC in blood with platelet clumps; values obtained by use of impedance can be considered minimums, and values obtained by use of buffy coat analysis may be either minimum values or reasonable estimates of PC.