Use of scintigraphy for assessment of fracture healing and early diagnosis of osteomyelitis following fracture repair in rabbits

OBJECTIVE: To evaluate use of technetium Tc 99m disodium hydroxymethylene diphosphonate (99m-Tc-HDP) for assessing fracture healing and 99m-Tc-HDP and technetium Tc 99m ciprofloxacin (99m-Tc-CIPRO) for early diagnosis of osteomyelitis in rabbits. ANIMALS: 32 skeletally mature New Zealand White rabbits. PROCEDURE: A femoral fracture defect stabilized with bone plates and cortical screws was used. Scintigraphy was performed 4, 8, 12, and 16 weeks after surgery. The 99m-Tc-CIPRO scan was performed 48 hours after the 99m-Tc-HDP scan. The uptake ratio of the experimental limb to the normal limb was calculated by use of multiple regions of interest. Results of radiography performed to determine external callus and lysis grade and percentage defect ossification at 16 weeks were compared with scintigraphy results. RESULTS: Infected fractures had a higher uptake ratio for 99m-Tc-HDP and 99m-Tc-CIPRO than noninfected fractures. Infected fractures could be differentiated from noninfected fractures late in healing by use of 99m-Tc-HDP. Although 99m-Tc-CIPRO was better than 99m-Tc-HDP for identifying infection, there was a high incidence of false positive and negative results with 99m-Tc-CIPRO. There was an association between 99m-Tc-HDP uptake ratio and callus formation and a good correlation between 99m-Tc-HDP uptake ratio and defect ossification after 4 weeks. CONCLUSIONS AND CLINICAL RELEVANCE: 99m-Tc-HDP and 99m-Tc-CIPRO may be useful for diagnosing osteomyelitis late in fracture healing; however, false positive and false negative results occur. Technetium Tc 99m disodium hydroxymethylene diphosphonate may be useful for evaluating fracture healing.     

Cyclooxygenase selectivity of nonsteroidal anti-inflammatory drugs in canine blood

OBJECTIVE: To evaluate cyclooxygenase (COX) selectivity of several nonsteroidal anti-inflammatory drugs (NSAID) in canine blood in vitro. ANIMALS: 11 healthy adult male hound crosses. PROCEDURE: 9 NSAID were studied at 5 concentrations. Thromboxane B2 (TxB2) was assayed as a measure of COX-1 activity in clotted blood. Prostaglandin E2 (PGE2) was assayed as a measure of COX-2 activity in heparinized, lipopolysaccharide (LPS)-stimulated blood. All assays were competitive ELISA tests. Cyclooxygenase selectivity was expressed as a ratio of the concentration of an NSAID that inhibited 50% of the activity (IC50) of COX-1 to the IC50 of COX-2. A separate ratio of the concentration that inhibited 80% of COX activity (IC80) was also determined. A ratio of < 1.0 indicated selectivity for COX-1, whereas a ratio of > 1.0 indicated COX-2 selectivity. RESULTS: Ketoprofen, aspirin, and etodolac were COX-1 selective. Piroxicam, meloxicam, and carprofen had COX-2 selectivity. The IC50 and IC80 values were similar for most NSAID. CONCLUSIONS: This methodology provides repeatable data from individual dogs and is comparable to results of previous in vitro and ex vivo models. Findings are also consistent with those of canine studies performed in vivo, suggesting that this is a viable in vitro assessment of the COX selectivity of NSAID in dogs.     

Comparison of individual and pooled sampling methods for detecting bacterial pathogens of fish.

Examination of finfish populations for viral and bacterial pathogens is an important component of fish disease control programs worldwide. Two methods are commonly used for collecting tissue samples for bacteriological culture, the currently accepted standards for detection of bacterial fish pathogens. The method specified in the Office International des Epizooties Manual of Diagnostic Tests for Aquatic Animals permits combining renal and splenic tissues from as many as 5 fish into pooled samples. The American Fisheries Society (AFS) Blue Book/US Fish and Wildlife Service (USFWS) Inspection Manual specifies the use of a bacteriological loop for collecting samples from the kidney of individual fish. An alternative would be to more fully utilize the pooled samples taken for virology. If implemented, this approach would provide substantial savings in labor and materials. To compare the relative performance of the AFS/USFWS method and this alternative approach, cultures of Yersinia ruckeri were used to establish low-level infections in groups of rainbow trout (Oncorhynchus mykiss) that were sampled by both methods. Yersinia ruckeri was cultured from 22 of 37 groups by at least 1 method. The loop method yielded 18 positive groups, with 1 group positive in the loop samples but negative in the pooled samples. The pooled samples produced 21 positive groups, with 4 groups positive in the pooled samples but negative in the loop samples. There was statistically significant agreement (Spearman coefficient 0.80, P < 0.001) in the relative ability of the 2 sampling methods to permit detection of low-level bacterial infections of rainbow trout.     

Growth-promotant implants: managing the tools.

Great contemplation, conversation, and controversy have surrounded the use of growth-promotant implants since their inception in the 1950s. Since the very beginning, the purpose of growth promotants has been to enhance production efficiency, reduce the cost of production, and improve profitability. Changes in our understanding of the physiologic mechanisms involved in growth promotion have not altered this fundamental purpose. With enhanced knowledge of the impact of various compounds and doses on different classes of animals, and with the introduction of numerous products providing those compounds and doses, planning implant programs has become difficult. However, the net return from a well-designed implant program may mean the difference between profit and loss on a given set of cattle.     

Pharmacokinetics of intravenous tramadol in dogs

The purpose of this study was to determine the pharmacokinetics of tramadol and the active metabolite mono-O-desmethyltramadol (M1) in 6 healthy male mixed breed dogs following intravenous injection of tramadol at 3 different dose levels. Verification of the metabolism to the active metabolite M1, to which most of the analgesic activity of this agent is attributed to, was a primary goal. Quantification of the parent compound and the M1 metabolite was performed using gas chromatography. Pharmacodynamic evaluations were performed at the time of patient sampling and included assessment of sedation, and evaluation for depression of heart and respiratory rates. This study confirmed that while these dogs were able to produce the active M1 metabolite following intravenous administration of tramadol, the M1 concentrations were lower than previously reported in research beagles. Adverse effects were minimal, with mild dose-related sedation in all dogs and nausea in 1 dog. Analgesia was not documented with the method of assessment used in this study. Tramadol may be useful in canine patients, but additional studies in the canine population are required to more accurately determine the effective clinical use of the drug in dogs and quantification of M1 concentrations in a wider population of patients.     

Expression of hedgehog family genes in the rat uterus during early pregnancy

Hedgehog (Hh) plays a pivotal role in various tissues during embryonic development, tissue homeostasis and tumorigenesis. In mammals, Hh exists in three homologs: Desert hedgehog (Dhh), Indian hedgehog (Ihh) and Sonic hedgehog (Shh). In this study, we cloned full-length cDNAs encoding Dhh and Ihh from the rat uterus. Their amino acid sequences have a high homology with those of the mouse and human. In addition, the changes of Hh gene expression in the rat uterus during early pregnancy were analyzed. The results showed that all three hedgehog mRNAs were detected in the rat uterus at the proestrus stage and during early pregnancy (1.5, 3.5, 5.5 and 7.5 days post coitus: dpc). Ihh mRNA expression varied and peaked at 3.5 dpc in the luminal and glandular epithelium. Expression was decreased on 5.5 dpc with the exception of sustained expression in the glandular epithelium. Despite such Ihh variability, the expressions of Dhh and Shh mRNA remained unchanged. This indicated that Ihh was mainly expressed in the rat uterus during early pregnancy. Moreover, the Hh target gene (glioma-associated oncogene homolog 1; Gli1) was also highly expressed at 3.5 dpc in the epithelium and periepithelial stroma in a manner similar to the temporal pattern of Ihh expression. This suggests that Ihh signaling axis play a role in the rat uterus during early pregnancy. In summary, our results elucidate that Ihh is a predominant Hh protein in the rat uterus during early pregnancy and that other Hhs have the potential to be expressed. This observation will help to elucidate the basic molecular mechanism of rat uterus during early pregnancy.     

Evaluation of the diffusion of corticosteroids between the distal interphalangeal joint and navicular bursa in horses

OBJECTIVE: To determine whether clinically effective concentrations of methylprednisolone or triamcinolone can be achieved in the navicular bursa after injection of methylprednisolone acetate (MPA) or triamcinolone acetonide (TA) into the distal interphalangeal joint (DIPJ) and whether clinically effective concentrations of these drugs can be achieved in the DIPJ after injecting the navicular bursa with the same doses of MPA or TA. ANIMALS: 32 healthy horses. PROCEDURES: Horses in groups 1 through 4 received 40 mg of MPA in the DIPJ, 10 mg of TA in the DIPJ, 40 mg of MPA in the navicular bursa, and 10 mg of TA in the navicular bursa, respectively. Concentrations of corticosteroids that diffused into the adjacent synovial structure were determined. RESULTS: For group 1, injection of MPA into the DIPJ yielded a mean +/- SD concentration of 0.24 +/- 0.072 microg of methylprednisolone/mL in the navicular bursa. For group 2, injection of TA into the DIPJ yielded 0.124 +/- 0.075 microg of triamcinolone/mL in the navicular bursa. For group 3, injection of MPA into the navicular bursa yielded 0.05 +/- 0.012 microg of methylprednisolone/mL in the DIPJ. For group 4, injection of TA into the navicular bursa yielded 0.091 +/- 0.026 microg of triamcinolone/mL in the DIPJ. CONCLUSIONS AND CLINICAL RELEVANCE: A clinically effective concentration of methylprednisolone or triamcinolone diffused between the DIPJ and navicular bursa after intra-articular or intrabursal injection, which would justify injection of the DIPJ with MPA or TA to ameliorate inflammation of the navicular bursa.