MRI of CNS lymphoma with choroid plexus involvement in five dogs and one cat.

OBJECTIVES: To describe the clinical features, magnetic resonance imaging (MRI) findings, and outcome of dogs and cats with central nervous system (CNS) lymphoma that involved the choroid plexus. MATERIALS AND METHODS: A bi-institutional retrospective study of MRI of dogs and cats with CNS lymphoma, in which the choroid plexus was affected on MRI. Signalment, clinical, MRI, clinicopathologic and histopathologic findings were recorded and evaluated. RESULTS: CNS lymphoma with choroid plexus involvement on the MRI was identified in five dogs and one cat. MRI revealed diffuse enlargement and multifocal nodularity in the choroid plexus in most cases, with the fourth ventricle the most common site affected. Five of the cases had signs of extraneural involvement (including the cat), while the sixth case was not staged. Four of five CSF samples analysed provided a diagnosis of lymphoma. CLINICAL SIGNIFICANCE: We report MRI findings of CNS lymphoma involving the choroid plexus. These results show the importance of recognising novel imaging patterns and the potential utility of CSF collection in diagnosing CNS lymphoma involving the choroid plexus ante mortem.

Risk Factors and Outcomes in Cats with Acquired Myasthenia Gravis (2001-2012).

BACKGROUND: Acquired myasthenia gravis (MG) in cats most commonly causes generalized weakness without megaesophagus and is more often associated with a cranial mediastinal mass, compared to dogs. HYPOTHESIS/OBJECTIVES: To extend the clinical findings described in the report of 2000 on MG in cats (J Am Vet Med Assoc 215:55-57). ANIMALS: Two hundred and thirty-five cats with MG. METHODS: Retrospective case study to evaluate the long-term outcome and incidence of spontaneous remission in myasthenic cats. Information including signalment, clinical presentation, presence of and type of cranial mediastinal mass, treatment including surgical versus medical, survival time, and outcome including spontaneous remissions was collected and analyzed in cats diagnosed at the Comparative Neuromuscular Laboratory, University of California San Diego by detection of acetylcholine receptor antibody titers >0.3 nmol/L by immunoprecipitation radioimmunosassay. RESULTS: Acquired MG in cats is associated with a euthanasia rate of 58%. Abyssinian and Somali cats had an increased incidence of MG compared to mixed breed cats or cats of other breeds. A cranial mediastinal mass, most commonly thymoma, was observed in 52% of the cats, which is higher than in the previous report. Spontaneous remission is not a characteristic of MG in cats. CONCLUSIONS AND CLINICAL IMPORTANCE: Myasthenia gravis in cats is a chronic disease associated with a high incidence of a cranial mediastinal mass. Spontaneous remission is not common and clinicians should warn owners of the necessity for long-term treatment. The clinical outcome with a cranial mediastinal mass did not differ between surgical or medical treatment.

Clinical, magnetic resonance imaging, and histopathologic findings in 6 dogs with surgically resected extraparenchymal spinal cord hematomas.

BACKGROUND: Extraparenchymal spinal cord hematoma has been described in veterinary medicine in association with neoplasia, intervertebral disk disease, and snake envenomation. There are rare reports of spontaneous extraparenchymal spinal cord hematoma formation with no known cause in human medicine. Multiple cases of spontaneous extraparenchymal spinal cord hematoma have not been described previously in veterinary medicine. OBJECTIVES: To describe the signalment, clinical findings, magnetic resonance imaging (MRI) features, and surgical outcomes in histopathologically confirmed extraparenchymal spinal cord hematomas in dogs with no identified underlying etiology. ANIMALS: Six dogs had MRI of the spinal cord, decompressive spinal surgery, and histopathologic confirmation of extraparenchymal spinal cord hematoma not associated with an underlying cause. METHODS: Multi-institutional retrospective study. RESULTS: Six patients had spontaneous extraparenchymal spinal cord hematoma formation. MRI showed normal signal within the spinal cord parenchyma in all patients. All hematomas had T2-weighted hyperintensity and the majority (5/6) had no contrast enhancement. All dogs underwent surgical decompression and most patients (5/6) returned to normal or near normal neurologic function postoperatively. Follow-up of the patients (ranging between 921 and 1,446 days) showed no progression of neurologic clinical signs or any conditions associated with increased bleeding tendency. CONCLUSIONS AND CLINICAL IMPORTANCE: Before surgery and histopathology confirming extraparenchymal hematoma, the primary differential in most cases was neoplasia, based on the MRI findings. This retrospective study reminds clinicians of the importance of the combination of advanced imaging combined with histopathologic diagnosis. The prognosis for spontaneous spinal cord extraparenchymal hematoma with surgical decompression appears to be favorable in most cases.

Voltage-independent calcium entry in hypoxic pulmonary vasoconstriction of intrapulmonary arteries of the rat.

It has been proposed that hypoxic pulmonary vasoconstriction (HPV) is mediated via K+ channel inhibition and Ca2+ influx through voltage-gated channels. HPV depends strongly on the degree of preconstriction, and we therefore examined the effect of Ca2+ channel blockade on tension and intracellular [Ca2+] ([Ca2+]i) during HPV in rat intrapulmonary arteries (IPAs), whilst maintaining preconstriction constant. We also investigated the role of intracellular Ca2+ stores. HPV demonstrated a transient constriction (phase I) superimposed on a sustained constriction (phase II). Nifedipine (1 microM) partially inhibited phase I, but did not affect phase II. In arteries exposed to 80 mM K+ and nifedipine or diltiazem the rises in tension and [Ca2+]i were blunted during phase I, but were unaffected during phase II. At low concentrations (< 3 microM), La3+ almost abolished the phase I constriction and rise in [Ca2+]i, but had no effect on phase II, or constriction in response to 80 mM K+. Phase II was inhibited by higher concentrations of La3+ (IC50 approximately 50 microM). IPA treated with thapsigargin (1 microM) in Ca2+-free solution to deplete Ca2+ stores showed sustained constriction upon re-exposure to Ca2+ and an increase in the rate of Mn2+ influx, suggesting capacitative Ca2+ entry. The concentration dependency of the block of constriction by La3+ was similar to that for phase I of HPV. Pretreatment of IPA with 30 microM CPA reduced phase I by > 80 %, but had no significant effect on phase II. We conclude that depolarization-mediated Ca2+ influx plays at best a minor role in the transient phase I constriction of HPV, and is not involved in the sustained phase II constriction. Instead, phase I appears to be mainly dependent on capacitative Ca2+ entry related to release of thapsigargin-sensitive Ca2+ stores, whereas phase II is supported by Ca2+ entry via a separate voltage-independent pathway.

A bibliography of drug discrimination research, 1992-1994.

The major content of this publication is a comprehensive bibliography of research into the discriminative stimulus effects of drugs in animal and human subjects for the period 1991-1994. The bibliography is accompanied by a detailed cross-index that facilitates access to this literature through keywords based on the drugs studied, how the drugs were used, and numerous other methodological variables such as species of subject and schedule of reinforcement. The article also explains how users may obtain access to the present and earlier versions of the database, which are available as computer disks and over the Internet. The easy access to this literature made possible by the database should increase the working efficiency of the many groups that employ drug discrimination methods and should also support dissemination of the knowledge acquired to a wider scientific community.

Developing a restraint use policy for acute care.

Restraint use has been a recent focus of attention in long-term care facilities. The Joint Commission on Accreditation of Healthcare Organizations, the Commission on Accreditation of Rehabilitation Facilities, and the Food and Drug Administration have devoted attention to the prudent use of restraints. The authors address efforts of an acute care facility to comply with these regulations.

Needs assessment. Process and application.

This article describes the process of developing a learning needs assessment. The process includes developing a tool, collecting data, and analyzing results. Understanding the needs assessment process and the pitfalls to avoid may assist educators in implementing their own learning needs assessments.

Cloning of cDNA for pyruvate, Pi dikinase from maize leaves.

To obtain molecular probes for studies of gene regulation in photosynthetic tissues of maize, we have cloned DNA complementary to poly(A)+RNA extracted from green leaves by insertion into plasmid pBR322 and transformation of E. coli, strain RR1. Colonies were screened by sequential hybridization with 32P-labeled single stranded cDNA synthesized from pooled aliquots of poly(A)+RNA fractionated by sucrose density centrifugation. Among the clones bearing cDNA homologous to high molecular weight poly(A)+RNA, we identified one with an insert of 440 base pairs homologous to mRNA for pyruvate, Pi dikinase, a C-4 carbon cycle protein localized in mesophyll cells of the leaf. Our work indicates that the dikinase subunits are synthesized in the cytoplasm as precursors approximately 13,000 daltons larger than the mature peptide subunits. Leaves of seedlings illuminated during growth have higher levels of pyruvate, Pi dikinase mRNA than leaves of dark-grown plants.

Light-stimulated synthesis of NADP malic enzyme in leaves of maize.

Illumination of etiolated maize plants for 80 h brings about a 15-20-fold increase in activity of NADP malic enzyme (EC 1.1.1.40). Increases in NADP malic enzyme protein and in the level of translatable mRNA for this protein occur simultaneously with the activity increase. Radiolabeled amino acids are also incorporated into NADP malic enzyme during this time. These results are consistent with the conclusion that an increase in NADP malic enzyme activity during greening results from de novo synthesis of NADP malic enzyme protein. Polyadenylated RNA extracted from greening maize leaves directs the synthesis in vitro of a protein 12,000 daltons larger than NADP malic enzyme purified from corn leaves. This protein is a precursor of NADP malic enzyme because 1) both the precursor and mature NADP malic enzyme are immunoprecipitated by antibody made against NADP malic enzyme purified from corn leaves, 2) both NADP malic enzyme protein and the level of mRNA for the precursor increase during greening, and 3) peptide maps of the precursor and of mature NADP malic enzyme are very similar. Mature NADP malic enzyme and its precursor (synthesized in vitro) both migrate on sodium dodecyl sulfate-polyacrylamide gradient gels as doublet bands. Peptide analyses show all bands to be structurally related.

Light-stimulated increase of translatable mRNA for phosphoenolpyruvate carboxylase in leaves of maize.

Polyadenylated RNA has been isolated from maize leaves at various times during greening of etiolated seedlings and used to prime the wheat germ cell-free translation system. Levels of translatable messenger RNA for phosphoenolpyruvate carboxylase increase with the length of the illumination period. The pattern of the increase in translatable mRNA for the enzyme is similar to that of the increase in phosphoenolpyruvate carboxylase protein previously observed in intact tissues. Phosphoenolpyruvate carboxylase synthesized in vivo migrates as a doublet band on gradient sodium dodecyl sulfate-polyacrylamide gels. A similar doublet has been seen occasionally with the products of cell-free translation.

Evidence for Light-stimulated Synthesis of Phosphoenolpyruvate Carboxylase in Leaves of Maize.

Illumination (22,000 lumens per meter(2)) of etiolated maize plants for 80 hours brings about a 5-fold increase in phosphoenolpyruvate carboxylase activity per unit of protein. An increase in carboxylase protein and incorporation of [(35)S]methionine into the protein occurs simultaneously with the activity increase. In green plants, the level of phosphoenolpyruvate carboxylase protein and enzyme activity is dependent on the intensity of light during growth. These results are consistent with the conclusion that the activity increase results from light-stimulated de novo synthesis of phosphoenolypyruvate carboxylase protein.

Studies on termination of protein synthesis in wheat germ.

Oligophenylalanines are soluble in m-cresol, but oligophenylalanyl-tRNAs are not. This differential solubility can be used to assay oligophenylalanines released from tRNA during their synthesis by wheat germ extracts. When poly U is the message, virtually no free product appears. When poly A U (A < U) is used, a considerable amount of oligophenylalanines are released. The fraction of product released is approximately constant with time, implying that a steady-state is not achieved between initiation and release. The dependence of release on various reaction variables and the effects of several inhibitors on release indicate that the reaction is probably catalyzed by peptidyl transferase, in accord with the mechanisms described for mammals and prokaryotes.