PubMed Health⌕ Search

Biomedical subjects

R P Shields

Publications and source records attributed to R P Shields.

17 recordsLinked to original sources
PubMed1992

Postanesthetic recumbency associated with hyperkalemic periodic paralysis in a quarter horse.

Anesthesia and surgery in a Quarter Horse affected with hyperkalemic periodic paralysis resulted in euthanasia after 7 days of postoperative recumbency. Initial recovery was uneventful after extensive sinus surgery, but within 2 hours, the horse had severe muscle weakness. Plasma electrolyte concentrations were within the normal range during the period of recumbency. There was no clinical or laboratory evidence of severe muscle damage. Despite treatment with acetazolamide, isoproterenol, and intensive nursing, the horse was unable to stand for more than a few seconds and developed severe decubital ulcers. Ultrastructural examination revealed nemaline rods and swollen mitochondria in disrupted myofibers.

Anesthesia, General↗
PubMed1992

Ultrastructural distribution of the M form of creatine phosphokinase in human muscle by immunogold labeling.

Creatine phosphokinase regenerates ATP from ADP using creatine phosphate. Isoenzymes of creatine phosphokinase are bound to certain cellular structures or are compartmentalized in areas of the cell, and this has been used as a basis for defining the role of these isoenzymes in energy metabolism. The M isoenzyme of creatine phosphokinase has been morphologically associated with the M-line of striated muscle in many species. In this present study the ultrastructural distribution and the relative concentration of the M form of creatine phosphokinase in human muscle tissue was determined using immunogold and electron microscopy. The M-line of the sarcomere, comprising only 3-4% of the sarcomere area, was found to contain over 20% of the total M isoenzyme signal of the entire sarcomere. This technique represents a quantitative, ultrastructural method to study the subcellular distribution of this isoenzyme. These data suggest that localized concentrations of M-CPK may be important for normal energy metabolism, and may also serve as a foundation for a better understanding of the relationship between abnormal creatine metabolism and the pathogenesis of neuromuscular disease.

Creatine Kinase↗
PubMed1979

Poxlike skin lesions in captive caimans.

Three juvenile captive spectacled caimans (Caiman sclerops) had scattered, gray-white, circular, 1- to 3-mm skin lesions. In one caiman, the lesions were particularly prominent on the phalanges, palpebrae, and integument overlying the maxillae and mandible. Digital biopsy revealed large eosinophilic intracytoplasmic inclusions within epithelial cells. Transmission electron microscopy of lesions from the lower jaw revealed viral particles morphologically similar to poxvirus.

Alligators and Crocodiles↗
PubMed1979

Mycotic pneumonia in mariculture-reared green sea turtles.

Microbiologic examination of 29 juvenile green sea turtles with a buoyancy abnormality revealed pulmonary infection with Sporotrichium sp, Cladosporium sp, and Paecilomyces sp. Histologic examination of the lungs revealed granulomatous lesions containing branching septate hyphae. The diagnosis was mycotic pneumonia.

Animals↗
PubMed1979

Intracardial mesotheliomas and a gastric papilloma in a giant grouper, Epinephelus itajara (Lichtenstein).

A giant grouper, Epinephelus itajara (Lichtenstein), was found dead in its tank. The principal necropsy findings consisted of multiple tumors in the ventricle of the heart, a tumor mass in the stomach, and protozoa-like organisms in the heart tumor, bile ducts and kidney collecting ducts. The heart tumors were identified as mesotheliomas the stomach tumor as a papilloma. The morphology of the protozoan-like organisms was similar to that of Rhabdospora thelohani (Languesse).

Animals↗
PubMed1979

Evaluation of room cleaning procedures in a laboratory animal facility.

Animal room cleaning procedures were developed that could be used routinely and economically in this animal facility. Bacterial samples from the floors of rooms housing rabbits, rats and mice provided a useful way to evaluate the effectiveness of the cleaning procedures, and to determine the in-use effectiveness of disinfectant solutions.

Animals↗
PubMed1979

Urolithiasis in ferrets (Mustela putorius).

Urinary calculi was observed frequently in ferrets which were from a group used for influenza research. They were submitted for necropsy with various clinical signs. The calculi were composed of magnesium ammonium phosphate hexahydrate and were found in the pelvis of the kidney, urinary bladder and urethra. Crystals of undetermined nature occasionally were observed in the kidneys.

Animals↗
PubMed1978

Spontaneous lower motor neuron disease in rabbits (oryctolagus cuniculus).

Spontaneous neurologic disease was observed in 6 to 8-week-old rabbits. Both males and females from several different litters were affected but all were sired by the same male. Clinically, the disease was characterized initially by posterior weakness and incoordination which progressed to tetraplegia within 3--4 weeks. With light microscopy there was neuronal degeneration and loss within the ventral horns of the spinal cord and brain stem and type-II fiber atrophy of skeletal muscles. Ultrastructurally the neuronal degeneration was characterized by accumulations of 100 A neurofilaments within the perikaryon. These findings are compared to diseases with neurofibrillary accumulation in animals and man.

Animals↗
PubMed1978

Effect of toxigenic Escherichia coli on myoelectric activity of small intestine.

When exposed to cholera toxin (CT), distal ileal loops of the rabbit small intestine showed an alteration in myoelectric activity. This alteration was defined as the migrating action potential complex (MAPC). The purpose of this study was to determine, using myoelectric recording techniques, the effects of live toxigenic Escherichia coli (TEC) on motility. Live TEC, live nontoxigenic E. coli (NTEC), and culture filtrates of these organisms were studied. Live TEC and its filtrate induced MAPC activity similar to that of CT. Live TEC induced a mean of 3.8 MAPCs/h, significantly greater than induced by live NTEC. TEC filtrate induced a mean of 14.2 MAPCs/h, significantly greater than NTEC filtrate. Heating the TEC filtrate to 100 degrees C before use resulted in a significant decrease of MAPC activity. This experiment demonstrated that live TEC and its culture filtrate altered ileal myoelectric activity. The effect may have been mediated by a heat-labile enterotoxin. This study suggests that alterations in small intestinal motility may be important in the pathogenesis of TEC diarrhea.

Action Potentials↗
PubMed1978

Ricinoleic acid effect on the electrical activity of the small intestine in rabbits.

Using myoelectric recording techniques, we examined the myoelectric effects of castor oil; ricinoleic acid (cis isomer), the active ingredient of castor oil; and ricinelaidic acid (trans isomer) in the small intestine of New Zealand white rabbits. Ricinoleic acid, 2 microgram/kg per min (6mM), was perfused into a distal 12-cm ileal loop. An abnormal myoelectric pattern developed that was similar to the alteration in the electrical activity that has previously been reported for cholera enterotoxin. Castor oil, 0.85 ml/kg, had a similar effect. Ricinelaidic acid, 2 microgram/kg per min, induced no activity. A second preparation consisted of an intraluminal perfusion of ricinoleic acid, 2 microgram/kg per min, into the first section of the duodenum. The abnormal myoelectric pattern was observed in the jejunum and the ileum but not the duodenum. The mean onset time for the development of this altered myoelectric state for all experiments was 3.5 h. These studies suggest that an active motility component in addition to the secretory state exists throughout the small intestine that is exposed to castor oil or ricinoleic acid.

Action Potentials↗
PubMed1978

Feline myeloproliferative disease. Changing manifestations in the peripheral blood.

A 4 1/2-year-old cat had myeloproliferative disease characterized by severe anemia. Peripheral blood had a profusion of relatively normal-appearing nucleated erythroid cells in all stages of development and a few primitive cells with nucleoli. The term "erythremic myelosis" best described the appearance of the peripheral blood. Two weeks later, the peripheral blood picture was that of regenerative anemia. During the next 2 months the cat made an apparent clinical recovery without treatment, but relapsed 3 months after the initial examination. One-fourth of the cells in circulation at the time of relapse contained nucleoli and appeared identical to those described in reticuloendotheliosis in cats. This transition suggested the progressive development of a greater degree of immaturity of erythroid precusors with time. The use of the term "reticuloendotheliosis" in conjunction with feline myeloproliferative disease was considered and determined inappropriate.

Animals↗
PubMed1977

Fatal generalized feline viral rhinotracheitis in a young adult cat.

A 7-month-old cat died following a 17-day illness. Necropsy findings included sharply demarcated lingual ulcers and multifocal necrotic hepatitis. Intranuclear inclusions were found in the lesions, and a herpesvirus was recovered from specimens of liver and tongue. The virus was identified by neutralization with specific antiserum as feline rhinotracheitis virus.

Animals↗
PubMed1976

Environmental monitoring in a laboratory animal facility.

A study was made of the microbial environmental status of an animal facility. Cultures were made of animal and surgical room floors; the germicidal effectiveness of the phenolic disinfectant-detergent employed in the facility was tested against standard test organisms as well as against other microorganisms isolated from the facility, and killing power of the disinfectant-detergent was evaluated during various steps of the usual cleaning procedures, ie, mops and mop bucket solutions were tested before, during, and after mopping a room. It was found that colony counts for animal rooms cleaned with a chlorhexidine disinfectant were much lower than those cleaned with a phenolic disinfectant. The phenolic disinfectant killed some organisms after 10 min exposure, but no others. Pseudomonads were the most resistant organisms. Contaminated mops and mop bucket solutions appeared responsible for the high counts on floors cleaned with the phenolic disinfectant. Guidelines for achievable levels of cleanliness were suggested.

Animals↗
PubMed1975

Fluroxene toxicity induced by phenobarbital.

Because of reports of fluroxene toxicity in man, the effect of phenobarbital treatment on the toxicity and metabolism of fluroxene was studied in 9 rhesus monkeys. Six monkeys that were exposed to a mean calculated alveolar fluroxene concentration of 5.8% for 4-hr periods up to a total of 16 hr showed no evidence of toxicity. Two animals were sacrificed after a single 4-hr exposure to obtain control measures of fluroxene metabolites in tissues. Four monkeys that had previously survived received exposures to fluroxene and 3 monkeys that had no exposure to fluroxene died during fluroxene anesthesia after treatment with phenobarbital (mean time, 3 hr). Toxicity was manifested by arterial hypotension, pulmonary edema, and arterial hypoxemia. Phenobarbital treatment enhanced production of fluroxene metabolites, including the highly toxic trifluoroethanol. Concentrations of trifluoroethanol in mixed-expired gas, blood, and urine, and of total nonvolatile fluorine in blood, urine, and tissues of animals treated with phenobarbital were 2 to 10 times as in control animals. The results suggest that the rhesus monkey is a valuable model for the study of fluroxene pharmacology and that inclusion of an enzyme-inducing challenge in the evaluation of potential toxicity of other anesthetics seems warranted.

Anesthesia↗
PubMed1975

Skeletal muscle function and structure after depletion of creatine.

Experiments were conducted to determine if normal skeletal muscle function and structure are dependent upon their ability to store large quantities of metabolic energy in the form of N-phosphorylcreatine. Muscle levels of creatine and N-phosphorylcreatine were reduced by feeding young male rats diets containing 1 per cent beta-guanidinopropionic acid (beta-GPA). Muscle function was evaluated by monitoring performance during a 4-week, short duration, high intensity exercise program in a control running wheel. Structural effects were determined by histochemistry, morphometric analysis, and routine histologic procedures using light microscopy. Evidence of abnormal creatine metabolism of rats fed beta-GPA included: excessive creatinuria, reduction in urine creatinine, reduced levels of muscle and brain creatine, and a reduced activity of muscle creatine kinase. In separate experiments, beta-GPA inhibited the reaction of creatine with creatine kinase in vitro. When muscle function was evaluated by running, the percentage of expected revolutions for the group of rats fed beta-GPA was below the expected normal values. The white (type II) fibers from the gastrocnemius of exercised rats fed beta-GPA were smaller than fibers from the same muscle areas of rats fed normal diets. The histochemical characteristics of red (type I) and white fibers of all rats tested were within normal limits. It is concluded that feeding beta-GPA will result in structural and functional changes in skeletal muscles of exercised young male rats. These changes are believed to result from the ability of beta-GPA to block creatine entry into muscle and thereby prevent muscle from accumulating and maintaining its normal complement of creatine and N-phosphorylcreatine.

Animals↗