Elution of antimicrobials from a cross‐linked dextran gel: In vivo Quantification

Reasons for performing study: Use of a novel, biodegradable, antimicrobial‐impregnated gel provides an alternative method of local treatment of infections in horses. Objectives: To determine in vivo elution of antimicrobial medications from antimicrobial‐impregnated cross‐linked dextran gel and to evaluate the effect on wound healing when implanted subcutaneously in horses. Methods: Amikacin‐, vancomycin‐ or amikacin/clindamycin‐impregnated gel was placed subcutaneously in 11 horses' necks, using 6 replicates with a 3 month washout between experiments. Capillary ultrafiltration probes for collection of interstitial fluid were placed 0 cm and 1.5 cm from the gel‐filled incisions. Samples were collected at 0, 4, 8 and 12 h, and on Days 1–10. Blood was collected on Days 0, 1 and 7. Amikacin and vancomycin samples were analysed via fluorescence polarisation immunoassay, and clindamycin samples via high‐performance liquid chromatography. Histology of biopsy samples was performed at the completion of the study. Differences in mean histomorphological scores between groups were assessed using Wilcoxon's signed ranks test. Results: Maximum antimicrobial concentrations were detected at 4 h (amikacin), and 8 h (vancomycin, and amikacin and clindamycin from the combination gel). Mean ± s.d. peak concentrations for amikacin, vancomycin, amikacin (amikacin/clindamycin) and clindamycin were 6133 ± 1461, 7286 ± 2769, 3948 ± 317 and 985 ± 960, respectively. Median number of days for which antimicrobial concentration remained above minimum inhibitory concentration for target microorganisms at implantation was ≥10 days for vancomycin, 9 days (± 1) for amikacin and 8 days (± 1) for clindamycin. Mean plasma amikacin and vancomycin concentrations were lower than detectable limits; mean serum clindamycin concentrations were 0.52 µg/ml and 0.63 µg/ml at 24 h and 7 days, respectively. There were no significant differences in histomorphological scores between treatment and control incisions (P≥0.22). Conclusions and potential relevance: Cross‐linked dextran gel is a safe, effective alternative local antimicrobial delivery method.     

Relationship between plasma creatinine concentration and glomerular filtration rate in dogs

Glomerula filtration rate (GFR), plasma creatinine concentration (CR), and plasma urea nitrogen concentration (BUN) were measured in 129 adult dogs with reduced renal mass. A preliminary examination of the relationship between CR and GFR was conducted, and the inverse model (GFR vs. 1/CR) was chosen for further evaluation. The slope of the regression of GFR on 1/CR which was computed from actual data was not statistically different from a theoretical regression line generated from the clearance equation.
Evaluation of subsets of the population revealed no significant difference between male ( n = 69) and female (n = 60) dogs on the slope of the regression equations. Diets differing in protein concentration (16% protein, n = 35: 21% protein, n = 75: 32% protein, n = 19) did not cause a significant difference in the slope of the regression equations.
The regression equation and the confidence intervals generated in this study may be used to predict a probable range of GFR values from CR in individual dogs. Such values may be useful in adjusting drug dosages in dogs with renal disease. However, since the derived equation did not differ significantly from the theoretical inverse relationship between GFR and CR, it remains to be established whether the equation is advantageous.     

Continuity and Change in an Old Industrial Region

Analysts have debated the extent to which recent economic changes represent a continuation of earlier patterns or a fundamental shift to a new industrial order. We trace and extend the spatial implications of this debate for a mature industrial region, the Ohio River Valley, part of the American Manufacturing Belt, for the 1980-90 period. The paper builds on recent research arguing that such regions had a diverse, rather than homogeneous, space-economy. Empirical findings clearly demonstrate diversity of economic structures, sectorally and spatially, emphasizing both continuity and change in an old industrial region, and the totality of economic activity rather than specific sectors identified with the rise or transformation of industrial capitalism. In terms of change, aggregate trends follow national ones, but do not wash evenly over the Ohio River Valley. Nor do they mirror, when considered at a sub-regional scale, patterns indicated by de-industrialization and post-Fordist transition frameworks. Findings provide implications for elaborating or augmenting these perspectives, and types of research needed to accomplish the task.