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Biomedical subjects

R L Tucker

Publications and source records attributed to R L Tucker.

At least 37 records · Page 2Linked to original sources
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↗
PubMed1985

Effects of morphine and atropine on motility and transit in the human ileum.

We examined motility of the ileocecal region, pressures at the ileocecal sphincter, and ileal flow after therapeutic doses of morphine and atropine. Using a factorial design in two cells of 8 (2(3] subjects, drugs were given during fasting and postcibally. Morphine (100 micrograms/kg body wt as a bolus intravenously) and atropine (7 micrograms/kg body wt as a bolus) stimulated migrating bursts of phasic activity (similar to phase III of the migrating motor complex). Morphine initially stimulated ileal flow, but atropine could not be shown to have this effect. Atropine reduced markedly the occurrence of sporadic pressure waves in the ileum, but morphine did not. Whereas atropine delayed mouth-to-ileum transit of polyethylene glycol, given in a mixed meal, morphine did not. Naloxone, in the dosage used (40 micrograms/kg body wt as a bolus, followed by 10 micrograms/kg body wt X h) had no independent effects on motility or flow, but did blunt the stimulatory effects of morphine and atropine on migrating motor complexes. We could not demonstrate an effect of any drug on the transit of lactulose from terminal ileum to cecum. Neither morphine nor atropine had impressive effects on tone at the ileocecal sphincter. These observations, while not specifying the mechanisms for constipation after opiates or anticholinergics, highlight the complexities of small bowel transit in humans and point out that the antidiarrheal effects of drugs are probably multifactorial.

Adult↗
PubMed1984

Motility of the terminal ileum and ileocecal sphincter in healthy humans.

Factors controlling the transit of contents between the ileum and cecum should be important determinants of intestinal function; however, the dynamics of the ileocecal region remain largely unexplored in healthy humans. Accordingly, prolonged recordings of intraluminal pressure were obtained from the distal ileum, across the ileocecal sphincter, and from the proximal colon of healthy adults. In one set of studies, 16 subjects each contributed 6 h of basal, fasting recordings; in 2 of the 16, postprandial patterns were also recorded. In a second set, 6 fasting subjects were studied for a total of 120 h. Less than 10% of interdigestive cycles (migrating motor complexes) reached the ileocecal sphincter. The remainder faded out and merged into an active, apparently random pattern of pressure waves that became more intense closer to the sphincter. Discrete, short bursts of phasic pressures migrated rapidly for long distances in the distal ileum and a unique peristaltic wave also migrated rapidly, though infrequently, through the region. Tonic pressures were recorded across the ileocecal sphincter but were present only during the passage of phasic pressure waves; basal tone was minimal. We believe these are the first prolonged observations of motility from the ileocecal sphincter of healthy humans. These descriptions provide insights into and a basis for further studies of a largely unexplored area of the human bowel.

Action Potentials↗
PubMedDate not supplied

Cerebral sinus venography in the dog: a new technique.

A new method of performing cerebral sinus venography was developed that opacifies both the ventral and most of the dorsal venous sinus systems. A pediatric angiographic catheter was introduced into the external jugular vein and advanced to the level of the temporal sinus. Iodinated contrast medium was injected manually and radiographs were made. Subtraction radiography was used to visualize vessels filled with contrast medium. Venography was simple and relatively non-invasive and was considered safe. The technique was used to confirm occlusion of the transverse venous sinus in healthy dogs that had undergone radical craniectomies.

Angiography↗
PubMedDate not supplied

Facial fibrosarcoma in two cows.

Fibrosarcoma is a common tumor affecting bone, but is uncommon in cows. Reported here are two bovine cases of facial fibrosarcoma that were very invasive.

Animals↗
PubMedDate not supplied

Use of magnetic resonance angiography for diagnosis of portosystemic shunts in dogs.

A prospective study was conducted to determine the sensitivity and specificity of diagnosis of portosystemic shunts (PSS) and the accuracy of anatomically locating single congenital PSS in dogs using magnetic resonance angiography (MRA). MRA was performed on 10 normal dogs and 23 dogs with PSS. Sensitivity and specificity of MRA to diagnose any shunt among all dogs were 80% and 100%, respectively. Among dogs identified with PSS, sensitivity and specificity of MRA for diagnosis of multiple extrahepatic shunts were 63% and 97%, respectively, and for diagnosis of single congenital shunts were 79% and 100%, respectively. Using MRA, radiologists correctly identified shunts as extrahepatic or intrahepatic in 83% of patients and correctly identified the origin and insertion of the shunts in 57% and 97% of patients, respectively. Use of MRA is specific for diagnosis of PSS and is a sensitive indicator of anatomic location of single congenital portosystemic shunts.

Animals↗
PubMedDate not supplied

Magnetic resonance imaging features of tumors of the spine and spinal cord in dogs.

Twenty-one dogs with confirmed tumors of the spinal cord or paraspinal tissues were imaged with magnetic resonance (MR) imaging. Anatomical location, location in relation to the dura and the medulla (spinal cord), and bone infiltration were assessed on the MR images and compared to findings at surgery or necropsy. Localization of tumors in the intradural-extramedullary compartment was not always possible. Bone infiltration was correctly assessed in all but one dog, and the anatomical locations involved were accurately determined in all dogs. Sagittal T2-weighted images were helpful to determine the anatomical location. Transverse T1-weighted images pre and post Gd-DTPA administration were helpful for additional localization and definition of tumor extension.

Animals↗
PubMedDate not supplied

Mensuration of the normal pituitary gland from magnetic resonance images in 96 dogs.

The pituitary gland was measured from transverse magnetic resonance T1-weighted images after Gadolinium administration in 96 dogs weighing from 13 to 45 kg. The measurements were done by hand with calipers. The mean (+/- standard deviation) pituitary gland height was 5.1 mm (+/-0.9 mm). The mean width was 6.4 mm (+/- 1.1 mm). The correlation coefficient between pituitary and brain measurements, between pituitary measurement and body weight, and brain measurements and body weight was 0.0 to 0.3. A hyperintense region was present on T1-weighted images in the center of the pituitary gland in 64% of the dogs. At necropsy the pituitary glands were grossly and histologically normal. No pituitary gland measurements were performed at necropsy.

Animals↗