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Biomedical subjects

R L Tucker

Publications and source records attributed to R L Tucker.

At least 19 recordsLinked to original sources
PubMed2001

Injury to the origin of the gastrocnemius muscle as a possible cause of lameness in four horses.

Four horses were evaluated because of hind limb lameness. Two had a distinct gait abnormality at the walk characterized by lateral rotation of the point of the calcaneus and medial rotation of the toe during the stance phase. Nuclear scintigraphy revealed a focal area of intense radioisotope uptake in the caudodistal aspect of the femur in all 4 horses, and 3 of the horses had a corresponding proliferative reaction on the caudodistal cortex of the femur on radiographs. In all 4 horses, a diagnosis of injury to the origin of the gastrocnemius muscle was made. Three of the horses returned to athletic endeavors after an extended period of rest and a gradual return to exercise. The fourth improved after 5 months of rest but became lame again when returned to exercise and was euthanatized.

Animals↗
PubMed2001

Diagnostic imaging of lameness in small animals.

The demand for advanced diagnostic imaging procedures such as nuclear scintigraphy, ultrasonography, computed tomography, and magnetic resonance imaging has increased dramatically over the past 10 years. Veterinarians, seeking to improve their diagnostic capabilities and clients willing to pursue "best medicine" have driven this demand, resulting in installation of advanced imaging facilities at most academic and private referral practices. Knowledge of potential benefits of various modalities will allow the veterinarian to optimize his or her use of diagnostic imaging in his or her own practice or in a referral practice.

Animals↗
PubMed2001

Computed tomography and magnetic resonance imaging of the equine head.

Horses are frequently presented with clinical conditions warranting diagnostic imaging of the head. Unfortunately, evaluation of the equine head can be difficult using conventional radiography. The anatomic complexity and superimposition of the osseous, dental, and soft tissue structures complicate radiographic interpretation and diagnoses. Multiple radiographic projections may be necessary to image specific regions, and side-to-side comparison is often essential.

Animals↗
PubMed2001

Computed tomography and magnetic resonance imaging of the equine musculoskeletal conditions.

There is a growing interest in the use of computed tomography (CT) and magnetic resonance (MR) imaging in equine orthopedic patients. It is well established that CT and MR imaging offer superior diagnostic information in a wide variety of musculoskeletal injuries in human beings and small animals. The highly detailed cross-sectional images obtained with these two modalities can often demonstrate pathologic changes undetected with other common imaging techniques. Based on their multiple applications in human beings and small animals, CT or MR imaging may prove to be the optimal diagnostic imaging technique for several types of musculoskeletal disorders of horses.

Animals↗
PubMed2000

Thyroid hormone coordinates respiratory control maturation and adenine nucleotide translocator expression in heart in vivo.

BACKGROUND: The signal transduction mechanism linking mitochondrial ATP synthesis with cytosolic ATP utilization in heart changes during postnatal development in vivo. This maturational process occurs in parallel with accumulation of mitochondrial adenine nucleotide translocator (ANT), which provides a possible site for respiratory control. We postulated that thyroid hormone regulates these maturational processes. METHODS AND RESULTS: We used (31)P MR spectroscopy to determine the relationship between myocardial high-energy phosphates, phosphocreatine, and ADP and oxygen consumption (MVO(2)) during epinephrine stimulation in 32- to 40-day-old lambs thyroidectomized after birth (THY) and age-matched controls. Steady-state protein and mRNA levels for ANT isoforms and beta-F(1)-ATPase were assessed from left ventricular tissues by Western and Northern blotting. With greater doses of epinephrine, THY attained lower peak MVO(2) than controls (P:<0.05). Controls maintained high-energy phosphate levels, unlike THY, which demonstrated significantly decreased phosphocreatine/ATP and increased cytosolic ADP despite lower peak MVO(2). No significant differences in beta-F(1)-ATPase protein or mRNA occurred between groups. However, ANT isoform mRNA levels were 2-fold greater and protein levels 4-fold greater in control hearts. CONCLUSIONS: These data imply that the maturational shift away from ADP-mediated respiratory control is regulated by thyroid hormone in vivo. Specific thyroid-modulated increases in ANT mRNA and protein imply that this regulation occurs in part at a pretranslational level.

Adenosine Diphosphate↗
PubMed1999

Relationship between VO2max, heart score and echocardiographic measurements obtained at rest and immediately following maximal exercise in thoroughbred horses.

We evaluated the relationships of heart score (HS) and echocardiographic measures to maximal oxygen consumption (VO2max), maximal cardiac output (Qmax), and maximal stroke volume (SVmax). Six fit, mature Thoroughbred horses weighing (mean +/- s.e.) 487 +/- 11 kg were run 4 times on an inclined (10%) treadmill. Each run consisted of a 3 min warm-up at 4 m/s followed by completion of an incremental exercise test in which each horse ran until VO2max was reached. Arterial and mixed venous blood was collected to determine arteriovenous oxygen content difference C(a-v)O2[ in the last 15 s of exercise. An ATL HDI 3000 ultrasound system and a 3.5 MHz phased array transducer were used to make echocardiographic measurements before and within 2 min of run completion. Guided M-mode echocardiographic measurements of left ventricular diameter (LVD), interventricular septal thickness (IVS) and left ventricular free wall thickness (LVFW) during diastole (D) and systole (S) were made from the right parasternal short axis view at the level of the chordae, and VO2 and C(a-v)O2 were measured as the appropriate M-mode view was recorded. Maximum heart rate (HRmax) was determined using a cardiotachometer, and HS was calculated on nonexercise days using the established technique. Maximum cardiac output and SVmax were calculated from the Fick equation and HRmax. Backward stepwise regression analysis was used to relate pre- and post exercise echocardiographic measurements and HS to VO2, Q, and SV at the time of measurement, and to VO2max, Qmax, and SVmax. Pre- and post exercise LVDD appeared to be the most important variable in these equations. Mean pre-exercise HR at the time of measurement was 54.7 +/- 1.9 beats/min, while the mean post exercise rate was 111.7 +/- 2.6 beats/min. The mean +/- s.e. VO2max was 150.4 +/- 13.2 ml/(kg.min). Heart score was not correlated with VO2max, Qmax, or SVmax. There was no significant difference between pre- and post exercise measurements of LVD, IVSS, and LVFWS.

Animals↗
PubMed1999

Thyroid adenocarcinoma in a bald eagle (Haliaeetus leukocephalus).

Thyroid adenocarcinoma was diagnosed in an adult bald eagle (Haliaeetus leukocephalus) with clinical signs of weakness manifested by inability to fly. Physical examination at the time of admission revealed dried blood in the pharynx and glottis and the presence of pharyngeal trichomonads. Radiographs revealed a large soft tissue mass in the area of the left coracoid and clavicular bones. One month following successful treatment for trichomoniasis, the bird suffered an acute episode of tracheal hemorrhage and died. Necropsy revealed a large mass within the interclavicular air sac. The histologic features were consistent with thyroid adenocarcinoma. This is the first report of thyroid neoplasia in a member of the order Falconiformes.

Adenocarcinoma↗
PubMed1998

Bone scintigraphy in the diagnosis of sacroiliac injury in twelve horses.

Nuclear bone scintigraphy was used to diagnose sacroiliac injury in 12 horses presented for nonspecific rear limb lameness. The most common history was decreased performance and/or a mild chronic rear limb lameness which could not be localised by routine lameness examination. The scintigraphic patterns of the 12 affected horses were compared to 5 normal horses and 10 horses with lameness not related to the pelvic region. Subjective and quantitative evaluation of the bone scans clearly separated the 12 affected horses from the 5 normal horses and the 10 horses with lameness from causes other than the sacroiliac joint disease. The 12 affected horses had a scintigraphic pattern of moderate to marked increased uptake of the radiopharmaceutical within the sacroiliac joint region on the side of lameness. In contrast, the 5 normal horses and 10 horses scanned for other causes of lameness, had a symmetric, or only slightly asymmetric pattern of radioisotope uptake. Although nonspecific for the type of injury, nuclear bone scintigraphy is considered sensitive for the detection of sacroiliac injuries in horses.

Age Factors↗
PubMed1998

Use of an in vitro biotinylation technique for determination of posttransfusion viability of stored canine packed red blood cells.

OBJECTIVE: To determine posttransfusion viability (PTV) of canine RBC stored for 35 days in an additive solution, using in vitro biotinylation and technetium-99m and chromium-51 (99mTc/51Cr) labeling techniques. SAMPLE POPULATION: 6 random source, adult dogs. PROCEDURE: RBC from dogs were labeled with N-hydroxysuccinimide biotin (NHS-biotin) or 99mTc/51Cr in a crossover design. One unit (450 ml) of whole blood was collected from each dog, processed into packed RBC, and stored for 35 days in an additive solution. The process was repeated at a later date, so that each dog had 2 units stored under similar conditions. Stored autologous RBC were then labeled with either NHS-biotin or 51Cr and reinfused. When 51Cr was used, labeled cells were infused simultaneously with freshly drawn cells labeled with 99mTc. Posttransfusion viability of labeled cells was determined by dividing counts per minute (99mTc/51Cr) or percentage of cells (NHS-biotin) labeled at 24 hours by counts per minute or percentage of cells labeled after infusion. RESULTS: Mean PTV of packed RBC stored for 35 days in an additive system was 80% when determined by biotinylation, 83% as determined by 99mTc/ 51Cr, and 81% as determined by 51Cr alone. CONCLUSIONS: In vitro biotinylation provides an acceptable, nonradioisotopic means of determining PTV of stored canine packed RBC. CLINICAL RELEVANCE: NHS-biotin can be used to determine maximal storage time of canine RBC prepared for transfusion purposes.

Adenosine Triphosphate↗
PubMed1997

Advanced diagnostic imaging modalities available at the referral center.

While many equine diagnostic imaging procedures can be done in field, some procedures require specialized facilities, equipment or expertise which are generally only available in referral or specialty practices. As client awareness of the availability and advantages of these diagnostic procedures increases, veterinarians are faced with the increasing opportunity to utilize these services to provide optimal patient care. A working knowledge of the value and limitations of these methods is required to help guide veterinarians and clients in the selection of additional, and sometimes costly, diagnostic tests.

Animals↗
PubMed1996

Brain imaging.

Advances in medical technology have revolutionized diagnostic brain imaging. Traditional radiography and invasive contrast studies for intracranial imaging have been superseded by several newer imaging modalities which provide high resolution, cross-sectional images. Ultrasonography, computed tomography, magnetic resonance, and nuclear scintigraphy are now used for anatomical and functional imaging of the brain. These noninvasive modalities are available at most veterinary teaching institutions and are offered through many larger referral practices. The diagnostic usefulness and clinical limitations for each of these modalities are described.

Animals↗
PubMed1995

Endoscopy of the auditory tube diverticula in four horses with otitis media/interna.

Endoscopic examination of the auditory tube diverticula was a diagnostic aid in the evaluation of 4 horses with otitis media/interna and associated osseous changes of the stylohyoid and petrous temporal. One of the horses was examined because of persistent head shaking; the other 3 were examined because of an acute onset of facial and vestibulocochlear nerve dysfunction. Proliferative lesions involving the petrous temporal bone and proximal portion of the stylohyoid bone were identified endoscopically in all 4 horses. Endoscopy is a noninvasive procedure that provides an alternative to skull radiography and tympanocentesis in the diagnosis of otitis media/interna in horses. In addition, risks associated with general anesthesia are avoided.

Animals↗
PubMed1995

Lag screw stabilization of a cervical vertebral fracture by use of computed tomography in a horse.

A traumatic fracture of C2 was diagnosed radiographically in a 1-year-old German Warm-blood stallion. Fracture configuration was difficult to see on survey radiographs. Computed tomography yielded a more accurate assessment of the fracture and facilitated fracture repair with cortical lag screws. Precise screw placement, to avoid spinal cord damage, was obtained by use of computed tomography. Follow-up radiography revealed normal bone healing, and the horse was in dressage schooling 24 months after surgery.

Animals↗
PubMed1993

Synovial sarcoma in a cat.

A 9-year-old male castrated cat was examined because of right forelimb lameness of 2 months' duration. The right cubital area was large, and the range of motion of the cubital joint was limited. Radiography revealed a mild periosteal reaction of the humerus, radius, and ulna. There was cortical remodeling of the distal portion of the humerus and punctate osteolysis within the proximal portion of the ulna. Arthrocentesis was performed and neoplastic cells were found, which led to a tentative diagnosis of osteogenic sarcoma or synovial cell sarcoma. Histologic diagnosis of synovial cell sarcoma was made after amputation of the limb.

Animals↗