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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
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↗
PubMed1992

In vitro comparison of equine granulocytes labeled with 99mTc-hexamethylpropyleneamine oxime or 111In-oxine.

Isolated equine granulocytes (WBC), radiolabeled with 99mTc-hexamethylpropyleneamine oxime (99mTc-HMPAO) or 111In-oxine, were evaluated in vitro for their labeling characteristics, viability, and phagocytic function over a 6-hour postlabeling period. Mean +/- SD labeling efficiency for 111In-oxine-WBC was 62.2 +/- 15.3%, which was significantly (P less than 0.001) higher than that for 99mTc-HMPAO-WBC (32.0 +/- 17.0%). In vitro elution of radiolabel from cells was significantly (P less than 0.02) greater for 99mTc-HMPAO-WBC at 0.5, 2, and 4 hours, but was not significantly different from elution of radiolabel for 111In-oxine-WBC at 6 hours. Viability, assessed by trypan blue dye exclusion, for 99mTc-HMPAO-WBC, 111In-oxine-WBC, and nonlabeled control WBC ranged from 97 to 100%, and was not significantly different among groups. Cell function was assessed by use of a phagocytosis assay and was reported as phagocytic index. The phagocytic index ranged from 0.86 to 0.96 for 99mTc-HMPAO-WBC, and from 0.76 to 0.97 for 111In-oxine-WBC. The phagocytic index was not significantly different at 0.5, 2, or 4 hours, but was significantly (P = 0.038) greater at 6 hours for 99mTc-HMPAO-WBC. Because of the superior imaging characteristics of 99mTc-HMPAO-WBC and equal or better labeling characteristics than those for 111In-oxine at 6 hours, 99mTc-HMPAO-WBC appear to be a good alternative to 111In-oxine-WBC.

Animals↗
PubMed1991

The implantable cardioverter-defibrillator: clinical results.

To evaluate the effectiveness of the automatic implantable cardioverter-defibrillator (AICD), a 7-year experience, from 1983-1990, was reviewed. A total of 111 patients received an AICD device. Their ages ranged between 8 and 83 years. Mean age was 63.9 years. There were 91 men and 20 women. Eighty of the patients received the AICD following an out-of-hospital cardiac arrest, while 31 were suffering from intermittent symptomatic ventricular tachycardia. The underlying etiology in 97 patients (87%) was ischemic coronary artery disease, in 11 patients (10%) dilated cardiomyopathy, and in 3 patients (3%) idiopathic ventricular fibrillation. Mean ejection fraction was 33.2%. Implantation of the AICD was performed via a left thoracotomy in 39 patients, median sternotomy in 49 patients and subxiphoid-subcostal approach in 23 patients. In-hospital mortality occurred in one patient who suffered an acute myocardial infarction 4 hours postoperatively. Out-of-hospital mortality was observed in 19 patients. There were two arrhythmic deaths. Follow-up was available for 107 patients. Mean follow-up was 33.1 months. Sixty-six patients (62%) had AICD shocks. The initial appropriate shocks occurred during the first postimplantation year in 91% of the patients. In 53 of the survivors, initial AICD shocks took place within 4.4 +/- 4.7 months from implantation. Thirteen of the 20 patients who died had received appropriate AICD shocks. In these patients, the time between implantation and first shock was 2.7 +/- 3.6 months whereas the time between implantation and death was 11.3 +/- 10.3 months (NS). We conclude that the AICD is effective in converting ventricular tachyarrhythmias and prolongs survival.

Electric Countershock↗
PubMed1991

Unprepared human colon does not discriminate between solids and liquids.

In five healthy male volunteers, we compared solid and liquid transit though the unprepared colon. 99mTc-diethylenetriaminepentaacetic acid in 10 ml saline was injected into the cecum through an orocecal tube at 1 ml/min immediately after a methacrylate-coated medication capsule was seen to deliver 111In-labeled Amberlite IR-120PLUS pellets (avg diam, 1.0 mm) into the cecum. Segmental transits through the ascending, transverse, descending, and rectosigmoid regions were determined using a dual gamma camera system and a variable region of interest program. There was no difference between solid [half time, 247 +/- 60 (SE) min] and liquid (312 +/- 88 min) emptying from the ascending colon. Colonic transit of solids and liquids was further compared by regional counts and stool outputs at 12 and 24 h. There were no significant differences between solids and liquids (P greater than 0.05). Our data suggest that transit through the unprepared human colon is not different for solids and small volumes of liquids, when these are delivered together to the ascending colon.

Adult↗
PubMed1989

The genetics of the Dras3-Roughened-ecdysoneless chromosomal region (62B3-4 to 62D3-4) in Drosophila melanogaster: analysis of recessive lethal mutations.

The genetic organization of interval 62B3-4 to 62D3-4 on the Drosophila third chromosome was investigated. The region (designated DRE) includes four known loci: Roughened (R; 3-1.4), defined by a dominant mutation disrupting eye morphology; the nonvital locus Aprt, structural gene for adenine phosphoribosyltransferase; Dras3, a homolog of the vertebrate ras oncogene; and 1(3)ecdysoneless (1(3)ecd), a gene that has been implicated in the regulation of larval molting hormone (ecdysteroid) synthesis. Overlapping chromosomal deletions of the region were generated by gamma-ray-induced reversion of the R mutation. Recessive lethal mutations were isolated based upon failure to complement the recessive lethality of Df(3L)RR2, a deletion of the DRE region that removes 16-18 polytene chromosome bands. A total of 117 mutations were isolated following ethyl methanesulfonate and gamma-ray mutagenesis. These and two additional define 13 lethal complementation groups. Mutations at two loci were recovered at disproportionately high rates. One of these loci is preferentially sensitive to radiation-induced mutational alterations. Additionally, an unusually low recovery rate for cytologically detectable rearrangement breakpoints within the gamma-ray-sensitive locus suggests that an interval of the DRE region closely linked to the R locus may be dominantly sensitive to position effects. Lethal phase analysis of mutant hemizygotes indicates that a high proportion of DRE-region loci (11 of 13) are necessary for larval development. Mutations in five loci cause predominantly first-instar larval lethality, while mutations in four other loci cause predominantly second-instar lethality. Mutations in two loci cause late-larval lethality associated with abnormal imaginal disc development. A temperature-sensitive allele of one newly identified complementation group blocks ecdysteroid-induced pupariation. This developmental block is overcome by dietary 20-hydroxyecdysone, suggesting that a second locus in the region in addition to l(3)ecd may play a role in the regulation of late larval ecdysteroid levels.

Animals↗
PubMed1987

The ecdysoneless (ecd1ts) mutation disrupts ecdysteroid synthesis autonomously in the ring gland of Drosophila melanogaster.

Ring glands dissected from homozygous l(3)ecd1ts wandering larvae and upshifted in vitro to the restrictive temperature, 29 degrees C, synthesize abnormally low quantities of ecdysteroid. Nevertheless, ecd1 ring glands retain the ability to respond at 29 degrees C to an extract prepared from wild-type larval neural tissues that presumably contain prothoracicotropic hormone (PTTH), although both basal and stimulated levels of synthesis are lower than those in wild-type ring glands. Extracts prepared from ecd1 neural tissue exhibit an unusually high level of PTTH activity. Mutant ring glands downshifted in vitro to the permissive temperature after removal from larvae maintained at 29 degrees C regain the ability to produce normal basal and stimulated ecdysteroid levels. Collectively, these experiments demonstrate that the ecd1 mutation disrupts the physiology of the ring gland at 29 degrees C autonomously and may also interfere with PTTH release.

Animals↗
PubMed1986

Human interdigestive motility: variations in patterns from esophagus to colon.

In most fasting mammals, motility of the foregut and small intestine undergoes regular cycles of activity. Much of the expanding knowledge of this phenomenon comes from species other than humans; however, disorders of these patterns are proposed as being clinically important. We report studies in 16 healthy humans in whom motility was recorded from intraluminal pressure sensors, both when fasting and after a meal, for prolonged periods. The recording system spanned the area from stomach to proximal colon in all subjects and included the lower esophagus in 11 of the 16 studied. Half the interdigestive cycles involved the esophagus, approximately one-third began in the gastroduodenal region, and the remainder commenced more distally. Fewer than half the migrating motor complexes were recognizable beyond the midpoint of the small bowel, and less than 10% reached the distal ileum. The migrating motor complex was more prominent at night; and its progression through the jejunum was then slower. Small meals (345-395 kcal) interrupted fasting patterns for 90-240 min, but the amount of fat did not influence the duration of these disruptions. Motility varied widely between and within individuals, and differences between normal patterns in the jejunum and ileum were particularly striking. Thus, levels of recordings must be defined accurately if putative abnormalities, of possible clinical significance, are to be interpreted correctly. Relating local motor patterns to the maximal rate of rhythmic contractions, which reflects the frequency of slow waves and is a guide to the level of the small bowel, may be helpful in this regard.

Adult↗