Effect of feeding on plasma antibiotic concentrations in Greyhounds given ampicillin and amoxycillin by mouth

In a cross-over study, six Greyhounds were dosed by mouth with ampicillin and amoxycillin at 20 mg/kg, using three different feeding regimens (no food, canned food prior to dosing, and dry food ad lib ) with each drug. Antibiotic levels in plasma were determined by microbiological assay at intervals after dosing.
Plasma ampicillin concentrations tended to be lower in fed than in starved Greyhounds, but amoxycillin levels were relatively unaffected by feeding. In starved Greyhounds, ampicillin gave higher early levels than amoxycillin.     

Melting Temperature and Partial Melt Chemistry of H2O-Saturated Mantle Peridotite to 11 Gigapascals

The H2O-saturated solidus of a model mantle composition (Kilborne Hole peridotite nodule, KLB-1) was determined to be just above 1000°C from 5 to 11 gigapascals. Given reasonable H2O abundances in Earth's mantle, an H2O-rich fluid could exist only in a region defined by the wet solidus and thermal stability limits of hydrous minerals, at depths between 90 and 330 kilometers. The experimental partial melts monotonously became more mafic with increasing pressure from andesitic composition at 1 gigapascal to more mafic than the starting peridotite at 10 gigapascals. Because the chemistry of the experimental partial melts is similar to that of kimberlites, it is suggested that kimberlites may be derived by low-temperature melting of an H2O-rich mantle at depths of 150 to 300 kilometers.     

Universality Classes of Optimal Channel Networks

Energy minimization of both homogeneous and heterogeneous river networks shows that, over a range of parameter values, there are only three distinct universality classes. The exponents for all three classes of behavior are calculated.     

Influence of dietary arginine and glycine content on thyroid function and growth of juvenile rainbow trout, Oncorhynchus mykiss (Walbaum)

Juvenile rainbow trout, held at 12°C on a 12 h light :12 h dark photocycle, were fed a constant ration (1 % of body wt day ^?1) of isonitrogenous and isoenergetic diets that varied in either arginine content (3.6-56.1 g kg^?1 dry matter; experiment 1), or glycine (3.3–118 g kg^?1 dry matter) and alanine (5.0-42.3 g kg^?1 dry matter) content (experiment 2). In experiment 1, the lowest dietary level of arginine depressed growth, feed efficiency, plasma l -thyroxine (T₄) and 3,5,3′-triiodo-l -thyronine (T₃) levels and hepatic T₄ 5’monodeiodinase (5'D) activity responsible for T₄-to-T₃ conversion. Over the dietary range of 7.1–56.1 g arginine kg^?1, there was no change in 5'D activity, despite an arginine stimulation of growth. The optimum level of arginine for growth was within the range of 14.1–28.1 g kg^?1 of the diet or 32–63 g kg^?1 of dietary protein. In experiment 2, an increase in dietary glycine level, at the expense of glutamic acid, increased 5'D activity without attendant elevation of the plasma T₃ level. The latter finding suggests that glycine also induced a compensatory increase in T₃ degradation rate. This may explain why the glycine-induced increase in 5'D activity was unaccompanied by any changes in growth indices. Alteration of dietary alanine content did not affect growth or thyroid function. We conclude that of the various dietary amino acids tested, only glycine led to a progressive stimulation of hepatic T₄ 5'D activity. However, because glycine likely enhanced T₃ degradation, no increases in plasma T₃ or growth indices were found. Glycine may serve as an advance signal that activates thyroid function immediately preceding or coincident with energy and nutrient (especially protein) intake. This, in turn, may improve the efficiency of nutrient absorption and/or post-absorptive anabolic events.     

Action of selected antibiotics on four common bacteria associated with diseases of fish

Abstract. Four bacteria commonly associated with diseases of fish ( Aeromonas hydrophila complex, Aeromonas salmonicida, Flexibacter columnaris -like organisms and Pseudomonas fluorescens ) were evaluated in a serial dilution system for susceptibility to four antibiotics commonly used in the treatment of bacterial fish diseases (chloramphenicol, erythromycin, furpyrinol and oxytetracycline). Findings were expressed as minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Furpyrinol was found to have the lowest MIC and MBC against A. hydrophila complex, A. salmonicida and F. columnaris-like organisms. MIC and MBC's for oxytetracycline were complicated by the presenceof R-plasmids, but were less than 4.0 mcg/ml for those without plasmids. Pseudomonas fluorescens was susceptible only to oxytetracycline. MIC for all groups of organisms using chloramphenicol was generally less than 16.0 mcg/ml. Susceptibility to erythromycin by these groups of organisms was greater than 16 mcg/ml.     

Comparative sensitivity of five fish cell lines to wild type infectious haematopoietic necrosis virus from two Oregon sources

Abstract. Five fish cell lines (CHSE-214, STE-137, RTG-2, EPC and FHM) were compared for sensitivity to infectious haematopoietic necrosis virus (IHNV) from samples obtained from naturally-infected fish. Infectious ovarian fluids were obtained from steelhead trout, Salmo gairdneri Richardson, at the Round Butte Hatchery in central Oregon and tissue homogenates were prepared from chinook salmon, Oncorhynchus tshawytscha (Walbaum), alevins during an IHN virus epizootic at the Elk River Hatchery in coastal Oregon. The only lines to show characteristic viral cytopathology by plaque or end-point dilution assay for the steelhead trout virus isolate were the EPC and FHM cell lines. The chinook salmon isolates produced CPE in CHSE-214, STE-137, FHM and EPC cells. The titre of the salmon virus isolate was 10-50-fold higher on FHM and EPC cells by both assay methods. Neither by end-point nor plaque assay did the Round Butte or Elk River isolates produce CPE on RTG-2 cells. With both virus isolants both cell lines showed that greater sensitivity was obtained with plaque assay than with end-point titration. Pre-treatment of the cells with the polycation, polybrene, did not increase the virus titre in either assay. However, a transient enhancement in virus titre was observed in polybrene-treated STE-137 and CHSE-214 cells.     

Response of Clementina de Nules citrus trees to summer deficit irrigation. Yield components and fruit composition

The effects of mid-summer regulated deficit irrigation (RDI) treatments were investigated on Clementina de Nules citrus trees over three seasons. Water restrictions applied from July, once the June physiological fruit drop had finished, until mid September were compared with a Control treatment irrigated during all the season to match full crop evapotranspiration (ET_c). Two degrees of water restrictions were imposed based on previous results also obtained in Clementina de Nules trees ( [Ginestar and Castel, 1996] and [González-Altozano and Castel, 1999]). During the RDI period, deficit irrigation was applied based on given reductions over the ET_c, but also taking into account threshold values of midday stem water potential (Ψ_s) of −1.3 to −1.5 MPa for RDI-1 and of −1.5 to −1.7 MPa for RDI-2. Results showed that water savings achieved in the RDI-2 treatment impaired yield by reducing fruit size. On the contrary, the RDI-1 strategy allowed for 20% water savings, with a reduction in tree growth but without any significant reduction in yield, fruit size nor in the economic return when irrigation was resumed to normal dose about three months before harvest. Water use efficiency (WUE) in the RDI trees was similar or even higher than in Control trees. RDI improved fruit quality increasing total soluble solids (TSS) and titratable acidity (TA). In conclusion, we suggest that the RDI-1 strategy here evaluated can be applied in commercial orchards not only in case of water scarcity, but also as a tool to control vegetative growth improving fruit composition and reducing costs associated with the crop management.     

Enteric redmouth bacterium: comparison of isolates from different geographic areas

Abstract. Characteristics of 18 strains of Yersinia ruckeri the causative agent of enteric redmouth disease, from a variety of hosts and a wide geographic range were compared. Except for variations in colonial morphology and in citrate, sorbitol, and trehalose reactions, the strains were morphologically and biochemically homogeneous. Sixteen strains reacted with antiserum against the first serotype reported, and one strain reacted with antiserum against a more recently reported serotype. One strain represented a third serotype. Evidence presented indicated that extension of the geographic range may not be entirely a result of the transport of carrier fish.     

Dispersal dynamics of post-larval blue crabs, Callinectes sapidus, within a wind-driven estuary

We examined how post‐larval blue crab (Callinectes sapidus) dispersal occurs within Pamlico Sound, NC, USA, a predominantly wind‐driven system. We sampled during multiple 24‐h periods over 2 years (2000–01) to relate the spatial distribution of post‐larvae in the water column with circulation patterns. A hydrodynamic model of the region was used to recreate dispersal trajectories and to assess potential transport mechanisms and pathways that link near‐inlet and across‐Sound nursery habitats. Most post‐larval blue crabs were collected in surface waters at night, and were consistently distributed within the north‐western region of Pamlico Sound. Particle‐tracking simulations suggested that dispersal from the inlets to across‐Sound nursery habitats only resulted from the combination of tidal and wind‐driven currents. Our simulation results further indicated that the northernmost inlet (Oregon Inlet) was the primary supplier of post‐larval blue crabs throughout the northern basin of Pamlico Sound, as crabs ingressing through Hatteras Inlet to the south were not retained within our study area. A dispersal pathway connecting Oregon Inlet and across‐Sound settlement habitats was evident from field observations. Collectively, our results indicate how multiple forcing agents, coupled with post‐larval vertical positioning within the water column, drive estuarine dispersal and connect spatially separated nursery habitats.