Age-related changes in the pharmacokinetics of marbofloxacin after intravenous administration in goats

The pharmacokinetics of marbofloxacin was studied in adult goats and 1-, 3- and 6-weeks-old kids after single dose i.v. dose of 2 mg/kg body weight. Drug concentration in plasma was determined by high-performance liquid chromatography (HPLC) and the data collected were subjected to compartmental kinetic analysis. Volume of distribution was relatively high in adult goats (Vss = 1.31 L/kg), and increased with age (Vss = 0.92 L/kg, 0.95 L/kg and 1.00 L/kg, in 1-, 3- and 6-weeks-old kids respectively). Total body clearance (Cl) also increased with age from 0.080 L/kg.h (1-week-old) to 0.097 L/kg.h (3-weeks-old), 0.18 L/kg.h (6-weeks-old) and 0.23 L/kg.h (adult goats). As a consequence of increased body Cl, area under the plasma concentration vs. time curve decreased with age (AUC = 27.46 microg.h/mL, 22.61 microg.h/mL, 11.86 microg.h/mL and 8.44 microg.h/mL in 1-, 3-, 6-weeks-old kids and adults, respectively) and a longer elimination half-life was found during the first 3 weeks of age (t1/2beta = 9.66 h, 8.25 h, 6.44 h and 7.18 h, in 1-, 3-, 6-weeks-old kids and adults, respectively). Mean residence time decreased with age from 11.86 h in 1-week-old kids to 9.63 h (3 weeks), 5.76 h (6 weeks) and 5.06 h in adult goats.     

Controlling the electronic structure of bilayer graphene

We describe the synthesis of bilayer graphene thin films deposited on insulating silicon carbide and report the characterization of their electronic band structure using angle-resolved photoemission. By selectively adjusting the carrier concentration in each layer, changes in the Coulomb potential led to control of the gap between valence and conduction bands. This control over the band structure suggests the potential application of bilayer graphene to switching functions in atomic-scale electronic devices.     

Identification of normal parameters for ultrasonographic examination of the equine large colon and cecum

Six healthy horses were examined by using transabdominal ultrasonography, as described (1-3), to evaluate activity and size of the large colon and cecum at various locations. Using size and number of sacculations, activity patterns and contractile frequency; significant differences that would allow ultrasonographic identification of dorsal versus ventral colons, if they were displaced, were not found. The cecum had significantly greater activity than the colon, and a trend was seen towards smaller sacculations in the cecum than in the large colon.