Geo-referenced spatiotemporal analysis of the urban citrus canker epidemic in Florida

ABSTRACT Five areas in urban Miami were identified to study the spread of Xanthomonas axonopodis pv. citri to determine if the practice of removing exposed citrus trees within 38.1 m of trees affected by citrus canker was adequate to curtail further bacterial spread. To accomplish this, 18,769 trees in dooryards were surveyed, geo-referenced by differential global positioning systems (GPS), and assayed for disease severity, age of infection, citrus cultivar, location of infection in tree, and canopy size. For each tree, the date the tree became infected was estimated and used to separate trees into contiguous 30-day categories. For each area studied, distance measurements between focal trees and newly infected trees were calculated for various temporal periods of 30, 60, 90, and 120 days in duration, corresponding to intervals of inspection survey. A visual basic application was used to calculate the distances between each newly diseased tree and all prior focal trees. The nearest distance was used because it was considered the most conservative estimate possible. It is therefore likely to be an underestimate of spread but is a good estimate of the minimum possible distances of spread. For the first four 30-day periods among the five study areas, calculated maximum distances of spread ranged from 12 to 3,474 m, indicating a broad continuum of distance for bacterial spread was possible. Disease increased during the first two-thirds of the time studied and reached an asymptote due to dry conditions in the final one-third of the duration of the study. Cross correlation analysis indicated that disease was best visualized 107 days following rainstorms with wind. Analysis of regional spatial point patterns was performed temporally for each 30-day period via a modified Ripley's K-function. Spatiotemporal analyses between periods over areas larger than previously examined were accomplished via spatiotemporal semivariogram analysis. These methods in combination demonstrated rapid increases in range of spatial dependency and range of spatiotemporal dependency for all study sites. This corresponded to rapid spread of disease across the regions studied in response to rainstorms with wind followed by a "filling in" of disease on remaining noninfected susceptible trees through time by less intense rain events. A stochastic quadratization technique demonstrated that disease incidence and disease severity were not greatly affected by urban host density but were positively correlated to host susceptibility within local 0.25-km(2) quadrats.     

Rostral maxillectomy and radiation therapy to manage squamous cell carcinoma in a ferret.

A 4-year-old, male, neutered ferret presented with squamous cell carcinoma of the right maxillary region associated with the tissues surrounding the upper canine tooth. A rostral maxillectomy was performed to excise the mass. Histopathologic examination showed questionable margins of tumor removal. Approximately 2 months after surgery, the ferret received a course of radiation therapy and is currently being monitored for tumor regrowth.     

Short-term biological variation of clinical chemical values in Dumeril's monitors (Varanus dumerili).

Plasma biochemical values are routinely used in the medical management of ill reptiles, and for monitoring the health of clinically normal animals. Laboratory tests, including clinical biochemical values, are subject to biological and analytical variation, the magnitude of which determines the utility of population-based reference ranges for the detection of abnormal results in the individual animal. Nested analysis of variance of repeated measurements allows the variance to be broken into within-individual, between-individual, and analytical variation. When the within-individual variation is large and the interindividual variation is low, a sample may be accurately classified as normal or abnormal based on a population-based reference interval. However, if the intraindividual variation is low and the interindividual variation high, population-based reference intervals are of limited value as the ranges for an individual encompass only a part of the conventional reference interval. Between-lizard, within-lizard, and analytical components of variance were assessed by nested analysis of variance for 16 commonly measured plasma biochemical parameters in eight healthy adult Dumeril's monitors (Varanus dumerili). Albumin, cholesterol, phosphate, calcium, sodium, and total protein demonstrated levels of individuality suggesting that comparison of a single measurement to a conventional population-based reference range may be too insensitive to detect small but significant alterations in the value for that animal. Only for potassium and AST did the index of individuality suggest that the use of reference values may be warranted. Uric acid, globulin, glucose, and amylase fell in a gray zone, where population-based ranges should be used with caution. The critical difference indicates the difference between two consecutive analytical results that may be safely ascribed to natural variation. In the present study critical difference varied from 7 and 11%, respectively, for sodium and chloride to 75 and 125% for uric acid and AST.     

THE DURAL TAIL SIGN IN THE DIAGNOSIS OF MENINGIOMAS

In humans the dural tail is a sign seen on contrast enhanced T1 weighted magnetic resonance images. This finding is considered specific for meningioma. The purpose of this study was to determine how often the dural tail occurs in cats and dogs and whether it is a specific sign for meningiomas in these species. MR examinations for eighteen dogs and four cats with proven diagnoses were reviewed. Diagnoses included ten meningiomas (seven dogs and three cats), three gliomas, two pituitary tumors, single examples of two other tumor types and five patients with mass lesions due to inflammatory disease. Contrast enhanced T1 weighted images were evaluated independently by three of the authors for the presence of a dural tail, without knowledge of the diagnoses. The results were compared to the diagnosis for each patient and the performance of individual reviewers compared. When their results were averaged, the reviewers reported the presence of a dural tail in 6 of 10 (60%) meningiomas, although detection varied between observers from 40% to 80%. Each reviewer had one false positive result, two reported a dural tail with a chromophobe adenocarcinoma and one with a toxoplasma meningoencephalitis. When a dural tail is seen an associated mass is most likely a meningioma. It is uncertain whether the dural tail represents neoplastic infiltration beyond the margins of the meningioma. This should be considered when planning treatment.     

Physiological Responses of Rainbow Trout Oncorhynchus mykiss to Crowding and Anesthesia with AQUI-S™

Abstract.— Following exposure to the anesthetic AQUI-S™, plasma cortisol concentration in immature rainbow trout was measured as (mean) 293 ± 48 ng/ mL, which was significantly ( P > 0.05) higher than the mean concentration in resting fish. Cortisol concentrations remained significantly ( P > 0.05) elevated for at least 24 h after treatment. This was accompanied by a significant increase and decrease in hematocrit and plasma potassium, respectively. These perturbations continued for at least 48 h following recovery from anesthesia. Plasma concentrations of total protein and sodium remained unchanged following anesthesia with AQUI-S™. Crowding stress is commonly encountered by fish during manipulation in aquaculture situations. Anesthetising fish prior to, and during, manipulation may reduce the associated stress. Changes in cortisol values resulting from crowding (30 min; 0.1 kg/L) during anesthesia with AQUI-S™ were not appreciably different from those in fish crowded without anesthesia. Thus, anesthesia with AQUI-S™ at the recommended dose of 17 mg/L did not appear to be effective for alleviating the stress of crowding under the conditions of our experiments.     

Effect of site preparation on survival and growth of Douglas-fir (Pseudotsuga menziessi Mirb. Franco.) seedlings

The performance (survival and growth) of Douglas-fir (Pseudotsuga menziesii Mirb. Franco.) seedlings planted in minimally disturbed, scalped, and bedded soils, both with and without herbicidal control of weeds, were compared. Douglas-fir growing for 3 years in bedded soils treated with herbicide were heavier, taller, and had deeper root systems than trees growing in other preparations. Scalping did not improve seedling performance when compared to minimally disturbed soils. Soils rich in organic matter benefited tree growth. Competing vegetation in raised beds was detrimental to seedling performance.     

Environmental and physiological controls over oxygen and carbon isotope composition of Tasmanian blue gum, Eucalyptus globulus

We measured oxygen isotope ratios (delta18O) of xylem sap, phloem sap, leaves, wood and bark of Eucalyptus globulus Labill. growing in southwestern Australia. Carbon isotope ratios (delta13C) were measured in the dry matter of phloem sap, leaves and wood. Results were used to test several aspects of a mechanistic model of 18O enrichment and provided insights into post-photosynthetic variations in dry matter delta13C. Xylem water delta18O varied little within the tree crown, whereas variation at the landscape-level was more pronounced, with plantations near the coast being enriched by up to 3 per thousand compared with plantations less than 100 km inland. Phloem water was significantly enriched in 18O compared with xylem water in two of three sampling campaigns; mean enrichments were 0.5 and 0.8 per thousand. Phloem sap sugars exported from E. globulus leaves closely reflected observed leaf water enrichment when diurnal variation in photosynthesis was taken into account. Photosynthetic rates were higher in the morning than in the afternoon, whereas leaf water 18O enrichment increased to maximum values in the afternoon. A non-steady-state model of leaf water 18O enrichment accurately predicted observed values through a full diel cycle. Mean estimates of the proportion of organic oxygen effectively exchanging with xylem water during cellulose synthesis were close to 0.40 for both leaves and wood. Carbon isotope ratios of nascent xylem tissues did not differ from those of phloem sap sugars collected concurrently, whereas nascent leaf tissues were depleted in 13C by 2 per thousand compared with phloem sap sugars, suggesting that, in E. globulus, 13C enrichment of sink tissues compared with source leaves does not result from an enriching process within the sink tissue.