A COMPARISON OF RADIOGRAPHY, COMPUTED TOMOGRAPHY, AND MAGNETIC RESONANCE IMAGING FOR THE DIAGNOSIS OF PALMAR PROCESS FRACTURES IN FOALS

The relative sensitivity of radiography, computed tomography, and magnetic resonance imaging for detecting palmar process fractures of the distal phalanx in foals was determined and the imaging findings were compared with histomorphologic evaluations of the palmar processes. Compared to radiography, computed tomography and magnetic resonance imaging did not improve the sensitivity for detection of palmar process fractures. Statistical agreement for palmar process fracture diagnosis was excellent among the three imaging modalities. Histomorphologic evaluations were more sensitive for diagnosis of palmar process fracture than any of the imaging modalities. Three-dimensional image reconstructions and volume measurements of distal phalanges and palmar process fracture fragments from computed tomography studies provided more complete anatomical information than radiography. Magnetic resonance imaging confirmed that the deep digital flexor tendon insertion on the distal phalanx is immediately axial to the site where palmar process fractures occur, and differentiated cartilage, bone, and soft tissue structures of the hoof.     

Influence of grain type on the insecticidal efficacy of two diatomaceous earth formulations against Rhyzopertha dominica (F) (Coleoptera: Bostrychidae)

Laboratory bioassays were carried out in order to evaluate the effectiveness of two diatomaceous earth (DE) formulations, Insecto and SilicoSec, against adults of Rhyzopertha dominica (F) in eight different grain commodities. The adherence of the two DEs to each grain was also measured. The eight grains tested were wheat, whole barley, peeled barley, oats, rye, triticale, rice and maize. These commodities were treated with the DEs at three rates, 0.75, 1.0 and 1.5 g DE kg(-1) grain. The mortality of R dominica adults was measured after 24 h, 48 h, 7 days and 14 days of exposure in the treated grains at 26 degrees C and 55% RH. After the 14-day mortality count, all adults were removed and the treated grains retained under the same conditions for a further 60 days. The treated grains were subsequently examined for F1 progeny. Significant differences were recorded among the eight grain types as well as between the DE formulations tested. After 14 days of exposure, even at the lowest DE rate for both formulations, adult mortality was high (>90%) in wheat and triticale. In contrast, adult mortality was significantly lower in peeled barley. Increasing the rate improved the efficacy of the DEs significantly in only some of the grains tested. Reproductive capacity in all the treated grains was significantly suppressed when compared with untreated grains. Generally, more F1 individuals of R dominica were noted in the treated peeled barley than in the other commodities. Significant differences in the percentage of DE retention were noted among the eight grains. The highest retention level was noted in rice (>87%) and the lowest in maize (<6%). However, the degree of DE adherence to a given grain was not always indicative of the effectiveness of DE against R dominica.     

Comparison of hematologic values and transforming growth factor-beta and insulin-like growth factor concentrations in platelet concentrates obtained by use of buffy coat and apheresis methods from equine blood

OBJECTIVE: To evaluate the buffy coat and apheresis methods for preparation of platelet concentrates from equine blood by comparing platelet and growth factor concentrations. ANIMALS: 15 mature mixed-breed geldings. PROCEDURE: Whole blood samples were collected and processed by use of a buffy coat or apheresis method to obtain platelet poor and platelet concentrated fractions. The PCV, WBC count, and platelet count were compared among whole blood samples, platelet poor fractions, concentrates obtained by use of the apheresis method (ie, apheresis platelet concentrates), and concentrates obtained by use of the buffy coat method (ie, buffy coat platelet concentrates). Concentrations of transforming growth factor-beta (ie,TGF-beta1 andTGF-beta2) and insulin-like growth factor were compared between buffy coat and apheresis platelet concentrates. RESULTS: Platelet concentrations were 8.9-fold and 5.2-fold greater in buffy coat and apheresis platelet concentrates, respectively, compared with whole blood. Platelet concentrations were 13.1-fold greater in filtered apheresis platelet concentrates, compared with whole blood. TGF-beta1 concentrations were 2.8-fold and 3.1-fold greater in buffy coat and apheresis platelet concentrates, respectively, and TGF-beta1 concentrations were 10.5-fold greater in filtered apheresis platelet concentrates, compared with whole blood. TGF-beta2 concentrations were 3.6-fold greater in apheresis platelet concentrates, compared with whole blood. Platelet concentrations correlated with growth factor concentrations across all blood and platelet fractions. White blood cell counts had a significant positive correlation with TGF-beta1 concentration in buffy coat platelet concentrates. CONCLUSIONS AND CLINICAL RELEVANCE: Platelets and TGF-beta1 can be concentrated reliably from equine blood by use of buffy coat or apheresis methods, without modification of the protocols used for humans.     

RADIOGRAPHIC CHARACTERISTICS OF THE FORELIMB DISTAL PHALANX AND MICROSCOPIC MORPHOLOGY OF THE LATERAL PALMAR PROCESS IN FOALS 3–32 WEEKS OLD

Developmental morphology of the forelimb distal phalanges and lateral palmar processes of 9 Thoroughbred foals aged 3–32 weeks was assessed using radiography, microradiography and histology. For inclusion in the study, all distal phalanges had no pathologic radiographic abnormalities.
Vascular channels that are characteristically found in the dorsal region of the distal phalanx were not evident radiographically in the palmar process. The proximal and distal angles of the palmar processes were separated by a lucent line continuous with the incisure in foals only through 12 weeks of age. The distal phalanges were triangular-shaped in foals 3–12 weeks of age, and were oval-shaped in older foals.
The palmar aspect of the distal phalanx was the major contributor to growth of the distal phalanx in the sagittal plane, especially between 3 and 12 weeks of age. Growth of the lateral palmar process occurred through the means of endochondral ossification. The body and cortices of the lateral palmar process were composed of coarse cancellous bone. Porosity within the lateral palmar process was greater in regions sampled axial, compared to abaxial, to the parietal sulcus and did not change with age.
A fracture was identified microradiographically and/or histologically in 9 of 18 (50%) and 10 of 17 (59%), respectively, of the lateral palmar processes examined. The fracture line was consistently associated with the parietal sulcus on the dorsal cortical surface and was always immediately abaxial to the deep digital flexor tendon attachment. No age-related morphological changes of the lateral palmar processes were identified with microradiography or histological examinations.     

Lontophoretic administration of dexamethasone into the tarsocrural joint in horses

OBJECTIVE: To determine whether iontophoretic administration of dexamethasone to horses results in detectable concentrations in synovial fluid, plasma, and urine. ANIMALS: 6 adult mares. PROCEDURE: Iontophoresis was used to administer dexamethasone. Treatments (4 mA for 20 minutes) were administered to a tarsocrural joint of each mare. The drug electrode contained 3 ml of dexamethasone sodium phosphate at a concentration of 4 or 10 mg/ml. Samples of synovial fluid, blood, and urine were obtained before and 0.5, 4, 8, and 24 hours after each treatment. All samples were tested for dexamethasone using an ELISA. Synovial fluid also was evaluated for dexamethasone, using high-performance liquid chromatography. RESULTS: The lower and upper limits of detection for dexamethasone in synovial fluid with the ELISA were 0.21 and 1.5 ng/ml, respectively. Dexamethasone administered at a concentration of 10 mg/ml was detected by the ELISA in synovial fluid of 5 mares from 0.5 to 24 hours and in urine of 4 mares from 0.5 to 8 hours after each treatment, but it was not detected in plasma. Mean synovial fluid concentration of dexamethasone was 1.01 ng/ml. Dexamethasone administered at a concentration of 4 mg/ml was detected by the ELISA in urine of 2 mares at 0.5 and 4 hours after treatment, but it was not detected in synovial fluid or plasma. CONCLUSIONS AND CLINICAL RELEVANCE: Iontophoresis cannot be considered an effective method for delivery of dexamethasone to synovial fluid of horses, because drug concentrations achieved in this study were less than therapeutic concentrations.     

A molecular graphics study of factors influencing herbicidal activity of oximes of 3-acyl-tetrahydro-2H-pyran-2,4-diones

Structure-activity relationships in oximes of a series of sixteen 3-acyltetrahydro-2H-pyran-2,4-diones, exhibiting a variety of pre- and postemergent herbicidal activities, have been studied by means of computer graphics methods. The most active compounds are potent grass-killers. This graminicidal activity appears to depend strongly on the size and shape of the substituent at the 6-position of the pyran. The activity correlates with both molar refractivity and fit to a hypothetical ‘receptor’ probably the active site of acetyl coenzyme A carboxylase. The herbicide sethoxydim and the pyrandione herbicides appear to mimic the transition state of the reaction catalyzed by acetyl-CoA carboxylase. The study has yielded a receptor model which defines clearly the three-dimensional binding reguirements of the pyran ring and the substituents at the 6 position. It is not capable of providing information on the structural requirements of the 3-acyl moiety. The model is capable of discriminating between active and inactive herbicidal compounds and provides a basis for the design of new herbicidal compounds with enhanced graminicidal activity.     

Effects of inhibitors for signaling components on the expression of the genes for nitrate reductase and nitrite reductase in excised barley leaves

Nitrate-induced accumulation of mRNAs for nitrate reductase and nitrite reductase was strongly inhibited by treatment with inhibitors of Ca²⁺ channels, protein phosphatases, and tyrosine protein kinases in excised barley leaves. It was shown that these components may be involved in the nitrate-response signaling pathways for the expression of nitrate and nitrite reductase genes in barley leaves.