Navigational ultrasound imaging: A novel imaging tool for aiding interventional therapies of equine musculoskeletal injuries

REASONS FOR PERFORMING STUDY

Navigational ultrasound imaging, also known as fusion imaging, is a novel technology that allows real-time ultrasound imaging to be correlated with a previously acquired computed tomography (CT) or magnetic resonance imaging (MRI) study. It has been used in man to aid interventional therapies and has been shown to be valuable for sampling and assessing lesions diagnosed with MRI or CT that are equivocal on ultrasonography. To date, there are no reports of the use of this modality in veterinary medicine.

OBJECTIVES

To assess whether navigational ultrasound imaging can be used to assist commonly performed interventional therapies for the treatment of equine musculoskeletal injuries diagnosed with MRI and determine the appropriateness of regional anatomical landmarks as registration sites.

STUDY DESIGN

Retrospective, descriptive clinical study.

METHODS

Horses with musculoskeletal injuries of the distal limb diagnosed with MRI scheduled for ultrasound-guided interventional therapies were evaluated (n = 17 horses with a total of 29 lesions). Anatomical landmarks used for image registration for the navigational procedure were documented. Accuracy of lesion location and success of the procedure were assessed subjectively and described using a grading scale.

RESULTS

All procedures were accurately registered using regional anatomical landmarks and considered successful based on our criteria. Anatomical landmarks were described for each lesion type. The addition of navigational imaging was considered to greatly aid the procedures in 59% of cases and added information to the remainder of the procedures. The technique was considered to improve the precision of these interventional procedures.

CONCLUSIONS

Navigational ultrasound imaging is a complementary imaging modality that can be used for the treatment of equine soft tissue musculoskeletal injuries diagnosed with MRI.

Cervical vertebral canal endoscopy in the horse: intra- and post operative observations

REASONS FOR PERFORMING STUDY

Despite modern medical diagnostic imaging, it is not possible to identify reliably the exact location of spinal cord compression in horses with cervical vertebral stenotic myelopathy (CVSM). Vertebral canal endoscopy has been successfully used in man and a technique for cervical vertebral canal endoscopy (CVCE) has been described in equine cadavers.

OBJECTIVE

To determine the feasibility and safety of CVCE in healthy mature horses.

METHODS

Six healthy mature horses were anaesthetised. A flexible videoendoscope was subsequently introduced via the atlanto-occipital space into the epidural space (epiduroscopy, Horses 1-3) or the subarachnoid space (myeloscopy, Horses 4-6) and advanced to the 8th cervical nerve. Neurological examinations were performed after surgery and lumbosacral cerebrospinal fluid (CSF) analysed in horses that had undergone myeloscopy.

RESULTS

All procedures were completed successfully and all horses recovered from anaesthesia. Anatomical structures in the epidural space (including the dura mater, nerve roots, fat and blood vessels) and subarachnoid space (including the spinal cord, blood vessels, arachnoid trabeculations, nerve roots and the external branch of the accessory nerve) were identified. During epiduroscopy, a significant increase in mean arterial pressure was recognised, when repeated injections of electrolyte solution into the epidural space were performed. In one horse of the myeloscopy group, subarachnoid haemorrhage and air occurred, resulting in transient post operative ataxia and muscle fasciculations. No complications during or after myeloscopy were observed in the other horses. CSF analysis indicated mild inflammation on Day 7 with values approaching normal 21 days after surgery.

CONCLUSIONS

Endoscopic examination of the epidural and subarachnoid space from the atlanto-occipital space to the 8th cervical nerve is possible and can be safely performed in healthy horses.

POTENTIAL RELEVANCE

Cervical vertebral canal endoscopy might allow accurate identification of the compression site in horses with CVSM and aid diagnosis of other lesions within the cervical vertebral canal.

COX-2-dependent and potentially cardioprotective effects of negative inotropic substances released after ischemia

During reperfusion, cardiodepressive factors are released from isolated rat hearts after ischemia. The present study analyzes the mechanisms by which these substances mediate their cardiodepressive effect. After 10 min of global stop-flow ischemia, rat hearts were reperfused and coronary effluent was collected over a period of 30 s. We tested the effect of this postischemic effluent on systolic cell shortening and Ca(2+) metabolism by application of fluorescence microscopy of field-stimulated rat cardiomyocytes stained with fura-2 AM. Cells were preincubated with various inhibitors, e.g., the cyclooxygenase (COX) inhibitor indomethacin, the COX-2 inhibitors NS-398 and lumiracoxib, the COX-1 inhibitor SC-560, and the potassium (ATP) channel blocker glibenclamide. Lysates of cardiomyocytes and extracts from whole rat hearts were tested for expression of COX-2 with Western blot analysis. As a result, in contrast to nonischemic effluent (control), postischemic effluent induced a reduction of Ca(2+) transient and systolic cell shortening in the rat cardiomyocytes (P < 0.001 vs. control). After preincubation of cells with indomethacin, NS-398, and lumiracoxib, the negative inotropic effect was attenuated. SC-560 did not influence the effect of postischemic effluent. The inducibly expressed COX-2 was detected in cardiomyocytes prepared for fluorescence microscopy. The effect of postischemic effluent was eliminated with applications of glibenclamide. Furthermore, postischemic effluent significantly reduced the intracellular diastolic and systolic Ca(2+) increase (P < 0.01 vs. control). In conclusion, the cardiodepressive effect of postischemic effluent is COX-2 dependent and protective against Ca(2+) overload in the cells.

Conserved residues of tumour necrosis factor and lymphotoxin constitute the framework of the trimeric structure

Four distinct areas of primary sequence conservation between known tumour necrosis factor and lymphotoxin polypeptides from various species can be recognized. When these amino acid sequences are highlighted in the three-dimensional structure, all are found in the same region, constituting the framework of the trimeric structure.

Coexistence of A- and B-form DNA in a single crystal lattice

It is well known that DNA can exist in a variety of conformations which can be interconverted by relatively mild changes in conditions. The in vivo conformation of DNA is usually thought to be the B form, but there is recent evidence that other conformations may be important in DNA-protein recognition. Different fragments of DNA crystallized under virtually identical conditions can form A, B or Z helices. A fragment that adopted an A conformation in a crystal was found in the B conformation in solution, whereas NMR spectroscopy of A-DNA films revealed the presence of a substantial amount of disordered B-DNA. Until now, however, a DNA fragment of a given sequence has not been crystallized in more than one global conformation. We report here an X-ray diffraction study of crystals of the DNA octamer dGGBrUABrUACC. In addition to a 'framework' of A-DNA, which gives discrete X-ray reflections, there are partially disordered B-DNA helices, recognized by their diffuse scattering features.

Ordered water structure in an A-DNA octamer at 1.7 A resolution

The crystal structure of the deoxyoctamer d(G-G-Br U-A-BrU-A-C-C) was refined to a resolution of 1.7 A using combined diffractometer and synchrotron data. The analysis was carried out independently in two laboratories using different procedures. Although the final results are identical the comparison of the two approaches highlights potential problems in the refinement of oligonucleotides when only limited data are available. As part of the analysis the positions of 84 solvent molecules in the asymmetric unit were established. The DNA molecule is highly solvated, particularly the phosphate-sugar back-bone and the functional groups of the bases. The major groove contains, in the central BrU-A-BrU-A region, a ribbon of water molecules forming closed pentagons with shared edges. These water molecules are linked to the base O and N atoms and to the solvent chains connecting the O-1 phosphate oxygen atoms on each strand. The minor groove is also extensively hydrated with a continuous network in the central region and other networks at each end. The pattern of hydration is briefly compared with that observed in the structure of a B-dodecamer.