PRELIMINARY EVALUATION OF 99mTECHNETIUM DIETHYLENETRIAMINE PENTAACETIC ACID, 99mTECHNETIUM DIMERCAPTOSUCCINIC ACID, AND 99mTECHNETIUM MERCAPTOACETYLTRIGLYCINE FOR RENAL SCINTIGRAPHY IN CORN SNAKES (ELAPHE GUTTATA GUTTATA)

The efficacy of three radiopharmaceuticals, 99mTc-diethylenetriaminepentaacetic acid (99mTc-DTPA), 99mTc-dimercaptosuccinic acid (99mTc-DMSA), and 99mTc-mercaptoacetyltriglycine (99mTc-MAG3), for renal imaging was examined in 16 corn snakes (Elaphe guttata guttata). All snakes received the radiopharmaceutical via an intracardiac injection. The kidneys could not be visualized in the three snakes that received 99mTc-DTPA or in the three snakes that received 99mTc-DMSA, but were well delineated in all 10 snakes receiving 99mTc-MAG3. These snakes were anesthetized and a dynamic frame mode acquisition was obtained for 30 min immediately following injection. A 60 s single static frame mode image was then obtained with the snake in a curled position. Two of the 10 snakes that received 99mTc-MAG3 were removed from further analysis because of suspected pericardial injections. Of the remaining eight snakes, the mean (+/- SD) renal uptake was 25 +/- 9.8% or 24 +/- 9.7%, with or without correction for residual injection site activity, respectively. Correction for remaining radioactivity in the heart does not appear to be necessary if it is less than 10% of the total dose. 99mTc-MAG3 provided consistently high quality images of the kidneys and further studies are warranted to evaluate its sensitivity for detecting decreased function in snakes with renal disease.     

In Vitro Model for Testing Novel Implants for Equine Laryngoplasty

Objective— To develop an in vitro laryngeal model to mimic airflow and pressures experienced by horses at maximal exercise with which to test laryngoplasty techniques.
Study Design— Randomized complete block.
Sample Population— Cadaveric equine larynges (n=10).
Methods— Equine larynges were collected at necropsy and a bilateral prosthetic laryngoplasty suture was placed with #5 Fiberwire^™ suture to achieve bilateral maximal arytenoid abduction. Each larynx was positioned in a flow chamber and subjected to static flow and dynamic flow cycling at 2 Hz. Tracheal pressure and flow, and pressure within the flow chamber were recorded at a sampling frequency of 500 Hz. Data obtained were compared with the published physiologic values for horses exercising at maximal exercise.
Results— Under static flow conditions, the testing system produced inspiratory tracheal pressures (mean±SEM) of −33.0±0.98 mm Hg at a flow of 54.48±1.8 L/s. Pressure in the flow chamber was −8.1±2.2 mm Hg producing a translaryngeal impedance of 0.56±0.15 mm Hg/L/s. Under dynamic conditions, cycling flow and pressure were reproduced at a frequency of 2 Hz, the peak inspiratory (mean±SEM) pharyngeal and tracheal pressures across all larynges were −8.85±2.5 and −35.54±1.6 mm Hg, respectively. Peak inspiratory flow was 51.65±2.3 L/s and impedance was 0.57±0.06 mm Hg/L/s.
Conclusions— The model produced inspiratory pressures similar to those in horses at maximal exercise when airflows experienced at exercise were used.
Clinical Relevance— This model will allow testing of multiple novel techniques and may facilitate development of improved techniques for prosthetic laryngoplasty.     

Quantifying the effects of individual and environmental variability in fish recruitment

The effect of environmental variability on fish recruitment is analysed using simple linear growth models. It is shown that variance in an individual's environment significantly increases the probability of recruitment. It is also argued that environmental variance should lead to differences in growth rates observed in recruited fish, and in the mean observed growth rate of the overall population. These conclusions are discussed with reference to recent observations from field studies.     

Covariation between the average lengths of mature coho (Oncorhynchus kisutch) and Chinook salmon (O. tshawytscha) and the ocean environment

We used the average fork length of age‐3 returning coho (Oncorhynchus kisutch) and age‐3 ocean‐type and age‐4 stream‐type Chinook (Oncorhynchus tshawytscha) salmon along the northeast Pacific coast to assess the covariability between established oceanic environmental indices and growth. These indices included the Multivariate El Niño‐Southern Oscillation Index (MEI), Pacific Decadal Oscillation (PDO), Northern Oscillation Index, and Aleutian Low Pressure Index. Washington, Oregon, and California (WOC) salmon sizes were negatively correlated with the MEI values indicating that ultimate fish size was affected negatively by El Niño‐like events. Further, we show that the growth trajectory of WOC salmon was set following the first ocean winter. Returning ocean‐type British Columbia‐Puget Sound Chinook salmon average fork length was positively correlated with the MEI values during the summer and autumn of return year, which was possibly a result of a shallower mixed layer and improved food‐web productivity of subarctic Pacific waters. Size variation of coho salmon stocks south of Alaska was synchronous and negatively correlated with warm conditions (positive PDO) and weak North Pacific high pressure during ocean residence.     

Modelling volume changes in peat under conifer plantations

It is proposed that the shrinkage of well-decomposed peat beneath conifer plantations owing to the irreversible loss of water takes place in two stages. The first stage of pure subsidence is followed by a second stage of the formation of natural aggregates with a network of large cracks and a slower rate of subsidence. A plot of specific volume against gravimetric water content for natural aggregates or for excised blocks dried artificially shows a linear relationship throughout the range of water content. The assumption of equi-dimensional shrinkage in stage two allows a prediction of the relative amounts of subsidence and crack formation. The shrinkage of non-cracking fibrous peat is also dealt with. A preliminary attempt at verification of the predictive model from measurements of crack volume or subsidence of ground level shows that the model gives values of the right order of magnitude.     

美洲鳗白仔对三种饵料的选择性及消化率研究

报道了美洲鳗( Anguilla rostrata )白仔对水蚯蚓( Tubifex sp )、卤虫( Artem ia sp )和鱼卵三种饵料的选择性、消化率及摄食后的生长情况。试验结果表明,美洲鳗白仔对上述3 种饵料的选择性明显不同:水蚯蚓> 卤虫> 鱼卵。从其对3 种饵料的消化率及生长情况来看,水蚯蚓和卤虫对美洲鳗白仔的饲养效果较好,而鱼卵的饲养效果则较差。