Effect of Preoperative Erythromycin or Dexamethasone/Vitamin C on Postoperative Abomasal Emptying Rate in Dairy Cows Undergoing Surgical Correction of Abomasal Volvulus

Objective— To determine the effects of preoperative erythromycin or combined dexamethasone/vitamin C treatment on postoperative abomasal emptying rate in cows undergoing surgical correction of abomasal volvulus (AV).
Study Design— Prospective, controlled, clinical study using a convenience sample.
Animals— Lactating Holstein–Friesian cows (n=45) with AV were alternately assigned to 3 groups (n=15): group C: untreated (control); group E: erythromycin (10 mg/kg intramuscularly [IM]); group D: dexamethasone (0.02 mg/kg intravenously [IV]) and vitamin C (10 mg/kg IV).
Methods— Drugs were administered 1 hour before surgical correction of AV. d -xylose solution (50%, 0.5 g/kg body weight) was injected into the abomasal lumen during surgery. Jugular venous blood samples for determination of serum d -xylose concentration were periodically obtained. Time to maximal serum d -xylose concentration (T_max-model) was pharmacokinetically determined.
Results— Abomasal emptying rate was significantly ( P <0.05) faster in group E (T_max-model=182±69 min; mean±SD) than in group C cows (T_max-model=237±64 min). Abomasal emptying rate was similar in group D (T_max-model=196±47 min) and group C. Both treatments improved postoperative milk yield within 1 day after surgery.
Conclusion— Preoperative injection of erythromycin (10 mg/kg IM) is an effective method for ameliorating postoperative abomasal hypomotility in cows with AV.
Clinical Relevance— Parenteral erythromycin can be recommended for preoperative treatment of cows with AV.     

Phytotoxic sites of action for molecular design of modern herbicides (Part 1): The photosynthetic electron transport system

A bird's eye review was tried to select the bio‐rational targets from known and novel plant‐specific ones for the molecular design of modern herbicides, which exhibit efficient phytotoxicity at a low‐use rate and preserve a good environment in the 21st century. In phytotoxic sites in the photosynthetic electron transport (PET) system discussed in the present article (Part 1), the generally called bleaching herbicides interfering with the biosynthesis of photosynthetic pigments, chlorophylls and carotenoids, and the biosynthesis of plastoquinone, were considered to be good models for the molecular design of modern herbicides. The PET itself was still considered as an interesting target site for new herbicides, although they need to exert their action in all green leaves of weeds to achieve herbicidal efficacy. Because these herbicides never form a tight binding with D1‐protein, their use‐rate cannot be expected to be as low as the herbicides inhibiting chlorophyll or branched amino‐acid biosynthesis. Other herbicidal targets found in chloroplasts, namely ATP and NADPH formations, have already been omitted from the worldwide biorational molecular design program of herbicides targeting the PET system.     

Connectivity of lobster (Homarus americanus) populations in the coastal Gulf of Maine: part II. Coupled biophysical dynamics

We used a coupled biophysical model to investigate larval transport and connectivity patterns in the Gulf of Maine lobster ( Homarus americanus ) population. Biological 'particles' were released at over 21 000 locations every 10 days over a 4-month hatching period, and were followed from hatching through late postlarval stage. In addition to circulation and dispersion, model calculations included spatial patterns of egg production, temporal patterns of hatching, temperature-dependent development, vertical distribution and mortality. We ran the model for three larval production seasons using the same hatching patterns and individual-based modeling parameters but different flow patterns in the coastal current system. Model results gave distribution and abundance patterns of competent postlarvae that closely resembled observed, alongshore patterns of lobster settlement density. We evaluated the relative contribution of all source regions to the total number of competent postlarvae in a series of medium-size zones along the coastal shelf, many of which are used in lobster management. Connectivity depended on many factors, including patterns of egg production and transport, and the location and size of the receiving zones. Self recruitment ranged from a few percent to >90% of competent postlarvae. Although it was common for postlarvae to come from many, often distant, sources, most of the competent postlarvae in a zone originated within one to two zones in the prevailing 'up-stream' direction, forming shorter connections along the coast than the energetic currents might otherwise suggest. Inshore migrations during summer hatching may contribute to these shorter patterns of connectivity. Transport in the prevailing 'upstream' direction was also indicated.     

A Novel Pin Distraction Device for Arthroscopic Assessment of the Medial Meniscus in Dogs

Objective— To describe an extra-articular joint distractor for meniscal examination and treatment during canine stifle arthroscopy.
Study Design— Case series.
Animals— Dogs ≥20 kg with suspected cranial cruciate ligament (CrCL) deficiency.
Methods— A custom designed linear side bar was constructed to allow invasive pin distraction of the stifle joint. Its design efficacy for distraction of the medial joint compartment, observation and probing of the medial meniscus, and value during meniscal surgery was evaluated by clinical use.
Results— Application of the stifle distractor medial to the stifle joint using 2 negative threaded pins was easily performed percutaneously without the need of power equipment; however, unintended intra-articular placement of 1 threaded pin occurred in 2 stifles, without appreciable consequence to joint function. Observation as well as thorough probing of the caudal horn of the medial meniscus, even in the presence of a prominent remnant of the CrCL or severe periarticular fibrosis, was possible. Partial meniscectomy was effectively performed as needed without apparent damage to the associated articular surfaces.
Conclusions— Distraction and translation of the medial compartment of the stifle joint using invasive pin distraction allowed observation and palpation of the caudal horn of the medial meniscus so that assessment and treatment were readily accomplished without apparent morbidity.
Clinical Relevance— With careful attention to accurate pin placement, invasive pin distraction of the medial compartment of the canine stifle joint may improve arthroscopic evaluation and treatment of meniscal pathology.     

Mapping of Split-Line Pattern and Cartilage Thickness of Selected Donor and Recipient Sites for Autologous Osteochondral Transplantation in the Canine Stifle Joint

Objective— To characterize donor and recipient sites for autologous osteochondral transplantation in the canine stifle joint with respect to split-line pattern and cartilage thickness.
Study Design— In vitro study.
Sample Population— Stifle joints (n=30) of dogs >20 kg.
Methods— Collagen network orientation of the hyaline cartilage coverage of the distal femur was assessed using split-line technique (n=10). Cartilage thickness was measured radiographically on osteochondral plugs harvested at the abaxial and axial surfaces of the femoropatellar joint (n=15), the most proximal abaxial aspect of the medial condyle (CO; n=5) and at both femoral condyles (n=15).
Results— Cartilage within the femoropatellar joint and both femoral condyles had mostly transversely orientated pattern of split-lines. Abaxial to the femoropatellar joint split-lines were absent. All donor sites had significantly thinner cartilage than the medial condyle (CM). Only the distal trochlea had cartilage thickness comparable to the lateral condyle (CL). The thinnest cartilage was found abaxial to the femoropatellar joint followed by CO, which was ∼2–3 times thinner than the cartilage at both condyles.
Conclusions— None of the investigated donor sites provided transplants of comparable cartilage thickness to CM. Transplants from within the femoropatellar joint should be harvested in priority as they reach cartilage morphology comparable to CL.
Clinical Relevance— Adjusting for cartilage thickness and split-line pattern may improve long-term outcome after autologous osteochondral transplantation. But surface curvature and donor-site morbidity have to be considered as well when choosing the most suitable donor site.     

Immunohistochemical Localization of RANK, RANKL and OPG in Healthy and Arthritic Canine Elbow Joints

Objective— To determine if the receptor activator of nuclear factor-κB–receptor activator of nuclear factor-κB ligand–osteoprotegerin (RANK–RANKL–OPG) system is active in bone remodeling in dogs and, if so, whether differences in expression of these mediators occur in healthy and arthritic joints.
Study Design— Experimental study.
Sample Population— Fragmented processus coronoidei (n=20) were surgically removed from dogs with elbow arthritis and 5 corresponding healthy samples from dogs euthanatized for reasons other than elbow joint disease.
Methods— Bright-field immunohistochemistry and high-resolution fluorescence microscopy were used to investigate the distribution of RANK, RANKL, and OPG in healthy and arthritic joints.
Results— All 3 molecules were identified by immunostaining of canine bone tissue. In elbow dysplasia, the number of RANK-positive osteoclasts was increased. In their vicinity, cells expressing RANKL, a mediator of osteoclast activation, were abundant whereas the number of osteoblasts having the potential to limit osteoclastogenesis and bone resorption via OPG was few.
Conclusions— The RANK–RANKL–OPG system is active in bone remodeling in dogs. In elbow dysplasia, a surplus of molecules promoting osteoclastogenesis was evident and is indicative of an imbalance between the mediators regulating bone resorption and bone formation. Both OPG and neutralizing antibodies against RANKL have the potential to counterbalance bone resorption.
Clinical Relevance— Therapeutic use of neutralizing antibodies against RANKL to inhibit osteoclast activation warrants further investigation.     

Biomechanical Comparison of Four Soft Tissue Replacement Materials: An In Vitro Evaluation of Single and Multilaminate Porcine Small Intestinal Submucosa, Canine Fascia Lata, and Polypropylene Mesh

Objective— To compare mechanical performance of 4 soft tissue replacement materials.
Study Design— Experimental.
Sample Population— Polypropylene mesh (PM), single-layer porcine small intestinal submucosa (SIS), multilaminate (4-layer) porcine small intestinal submucosa (MLSIS), and canine fascia lata (FL).
Methods— The mechanical properties of each material were determined by testing to failure on a materials testing machine. Samples of each material (n=10) were tested in 3 different modes: resistance to suture pullout, tensile testing, and push-through testing. PM was tested both parallel (PMa) to and perpendicular (PMb) to its longitudinal cord orientation. SIS and FL were similarly tested in 2 orthogonal directions.
Results— With some exceptions, the following generalizations can be made regarding the mechanical performance of the materials tested:
Suture pullout— FL>PMa=PMb>MLSIS>SIS ( P ≤.04).
Tensile testing —FL>PMa>PMb>MLSIS>SIS ( P ≤.02).
Push-through testing— FL>PM>MLSIS>SIS ( P ≤.003).
Conclusions— PM accommodated a significantly higher load and energy to yield when its longitudinal cords were oriented parallel with the tension axis (PMa). FL performed similarly to the PM, with the exception of limited elongation in tension. MLSIS had biomechanical characteristics that were inferior to FL and PM but superior to SIS.
Clinical Relevance— PM's orientation may need to be considered when used clinically. FL is a biomechanically suitable soft tissue replacement material but its use may be limited by currently available sizes. SIS cannot be recommended in high-strain environments.     

IN VITRO EVALUATION OF FELINE LEUKOCYTES RADIOLABELED IN WHOLE BLOOD WITH 99MTC STANNOUS COLLOID

Technetium-99m stannous colloid (^99mTcSnC) has been used to radiolabel human leukocytes to investigate various inflammatory disorders. We investigated the in vitro behavior of feline leukocytes labeled in whole blood with ^99mTcSnC. Heparinized blood samples were collected from healthy cats and divided into control and test aliquots. The latter were labeled with ^99mTcSnC using a standard procedure. Leukocyte viability was determined for each sample using a trypan blue exclusion test. Labeling efficiency was determined for test aliquots. Test aliquots were layered onto Histopaque-1077^® and centrifuged before measurement of radioactivity of the blood components. Leukocytes from radiolabeled and control samples were washed and incubated with opsonized zymosan particles to allow assessment of phagocytic function. Aliquots were taken from radiolabeled feline leukocyte samples at 1, 3, 4, and 7 h postlabelling. After centrifugation of each aliquot, radioactivity of the supernatant and pellet was measured and the labeling retention determined. Leukocyte viability in both radiolabeled and control samples was >98%. The labeling efficiency was 95.2±0.14%. The distribution of radioactivity in feline blood was found to be 3.4±0.18% in plasma, 39.0±0.37% in erythrocytes, and 57.6±0.38% in leukocytes. Labeled feline leukocytes had phagocytic activity of 90.9±0.18% (control 91.3±0.15%). The radiolabeled leukocytes retained 93.4±0.19% of the radioactivity up to 7 h postlabeling. ^99mTcSnC efficiently labeled feline leukocytes with no effect on viability and minimal effect on phagocytic function. The percentage retention of radioactivity by the leukocytes was still high at 7 h postlabeling.