Beneficial effects of microsurgical lymphatic reconstruction after intestinal transplantation in rats.
Explore the source record for details and available documents.
Animals↗
Biomedical subjects
D Grant
Publications and source records attributed to D Grant.
Probable mechanisms underlying interallelic complementation and temperature-sensitivity of mutations at the shibire locus of Drosophila melanogaster.
The shibire locus of Drosophila melanogaster encodes dynamin, a GTPase required for the fission of endocytic vesicles from plasma membrane. Biochemical studies indicate that mammalian dynamin is part of a complex containing multiple dynamin subunits and other polypeptides. To gain insight into sequences of dynamin critical for its function, we have characterized in detail a collection of conditional and lethal shi alleles. We describe a probable null allele of shi and show that its properties are distinct from those of two classes of lethal alleles (termed I and II) that show intergroup, interallelic complementation. Sequenced class I alleles, which display dominant properties, carry missense mutations in conserved residues in the GTPase domain of dynamin. In contrast, the sequenced class II alleles, which appear completely recessive, carry missense mutations in conserved residues of a previously uncharacterized "middle domain" that lies adjacent to the GTPase region. These data suggest that critical interactions mediated by this middle domain are severely affected by the class II lethal mutations; thus, the mutant sequences should be very useful for confirming the in vivo relevance of interactions observed in vitro. Viable heteroallelic combinations of shi lethals show rapid and reversible temperature-sensitive paralytic phenotypes hitherto only described for the ts alleles of shi. When taken together with the molecular analysis of shi mutations, these observations suggest that the GTPase domain of dynamin carries an intrinsically temperature-sensitive activity: hypomorphic mutations that reduce this activity at low temperatures result in conditional temperature-sensitive phenotype. These observations explain why screens for conditional paralytic mutants in Drosophila inevitably recover ts alleles of shi at high frequencies.
Alleles↗
cDNA cloning and expression of a novel family of enzymes with calcium-independent phospholipase A2 and lysophospholipase activities.
Previous studies have suggested that activation of calcium-independent PLA2 (CaIPLA2) is an early event in cell death after hypoxic injury in proximal tubule cells. An approximately 28-kD CaIPLA2 with preferential activity toward plasmalogen phospholipids has been recently purified from rabbit kidney cortex (D. Portilla and G. Dai, J Biol Chem 271, 15,451-15,457, 1996). Their report describes the cloning of a full-length rat cDNA encoding CaIPLA2, using sequences derived from the purified rabbit kidney cortex enzyme. In addition, cDNA from rabbit kidney that encode the rabbit homologue of the enzyme and a closely related isoform were isolated. The rat cDNA is predicted to encode an approximately 24-kD protein, and each cDNA contains the sequence G-F-S-Q-G, which fits the active site consensus sequence G-X-S-X-G of carboxylesterases. Several lines of evidence (DNA sequence comparison, Southern blot analysis, and examination of the expressed sequence tag database) show that CaIPLA2 enzymes are encoded by a multigene family in rats, mice, rabbits, and humans. Northern analysis of various tissues from the rat indicated that the CaIPLA2 gene is ubiquitously expressed, with highest mRNA abundance observed in the kidney and small intestine. The rat CaIPLA2 cDNA, when expressed in a baculovirus expression system, and the purified rabbit kidney cortex protein exhibit both CaIPLA2 and lysophospholipase activities. The cloned CaIPLA2 cDNA are expected to aid in understanding the role of CaIPLA2 in cell death after hypoxic/ischemic cell injury.
Amino Acid Sequence↗
A caution in the use of laryngeal sprays. 1898.
Explore the source record for details and available documents.
Cardia↗
Bills for noninsured services remain a wellspring for patients' complaints.
Why do many canadians become angry when told they have to pay for noninsured medical services? Dorothy Grant hears many protests about this type of billing in her job with the Medical Society of Nova Scotia. Here she describes steps doctors can take to reduce the number of complaints.
Alberta↗
Arteritis and increased intracellular calcium as a possible mechanism for tacrolimus-related cardiac toxicity in a pediatric transplant recipient.
We recently reported partially to wholly reversible hypertrophic cardiomyopathy, including severe hypertrophic obstructive cardiomyopathy, as a side effect in pediatric transplant recipients receiving tacrolimus immunosuppression. This seemed to be dose related. We describe a pediatric patient receiving tacrolimus who died 3 weeks after liver/bowel transplantation. Postmortem findings revealed arteritis of cardiac arteries and extensive calcification of cardiac tissue suggesting a possible mechanism of tacrolimus cardiac toxicity. This is consistent with recent reports of tacrolimus increasing calcium release into the sarcoplasmic reticulum of cardiac and striated muscle.
Arteritis↗
Medical examiners' seminar looked at mysteries surrounding sudden death.
Medical examiners in Nova Scotia recently attended their first-ever seminar concerning the skills, challenges and techniques their jobs require. It was welcomed by the physicians, most of whom are family physicians with little training in the investigation of sudden death.
Coroners and Medical Examiners↗
Peer review is a two-way process.
Explore the source record for details and available documents.
Peer Review↗
Budesonide, a locally acting steroid, prevents graft rejection in a rat model of intestinal transplantation.
BACKGROUND: The requirement for potent systemic immunosuppression to prevent intestinal graft rejection has resulted in high rates of infection and post-transplant lymphoproliferative disease. Budesonide (BUD) is a locally acting steroid that is almost completely metabolized during its first pass through the intestinal wall and liver. The present study examined whether BUD could prevent small bowel allograft rejection without causing the adverse systemic effects associated with prednisolone. METHODS: Orthotopic Brown Norway to Lewis rat small bowel allotransplants were randomly assigned to treatment with low-dose BUD (0.1 mg/kg/day, p.o.) and high-dose BUD (1.0 mg/kg/day, p.o.) with and without cyclosporine (CsA; 2 mg/kg/day s.c.). The following parameters were assessed: allograft survival, recipient plasma adrenocorticotrophic hormone (ACTH) levels, recipient adrenal, splenic and thymic weights, recipient CsA levels, and graft histopathology. RESULTS: Low- and high-dose BUD alone did not prolong graft survival compared with the untreated group (9.1+/-0.4 days vs. 11+/-0.8 days vs. 9.7+/-0.4 days, respectively). However, when low-dose BUD and high-dose BUD were given in combination with CsA, the mean graft survival times were prolonged to 27.6+/-5.3 and 36.6+/-8.0 days, respectively (P<0.01). ACTH levels, adrenal weights, and thymic weights were not significantly different in the treatment and control groups receiving intestinal transplants. CONCLUSIONS: BUD enhances the immunosuppressive effects of CsA and prolongs small bowel allograft survival in rats without inhibiting normal ACTH release. These data suggest that BUD may be a useful immunosuppressive agent for clinical intestinal transplantation.
Adrenocorticotropic Hormone↗
MDs must help eliminate 911 calls after "expected" home deaths, medical examiner advises.
More and more Canadians are choosing to die at home. Unfortunately, family members may not know how to respond when death does occur. Some call 911 seeking advice, and soon find police, ambulance and fire services arriving at their door. If calls are made before terminal patients die, they may even be rushed to hospital for emergency care. The wasted energy wastes money and creates additional stress. Dr. John Butt, Nova Scotia's chief medical examiner, says physicians must help educate the public and emergency services about how to respond after an expected death occurs at home.
Coroners and Medical Examiners↗
Antisense gene inhibition by C-5-substituted deoxyuridine-containing oligodeoxynucleotides.
Antisense oligodeoxynucleotides (ODNs) are capable of inhibiting gene expression via a RNase H mechanism in which the complementary RNA is degraded by RNase H. C-5 propyne dU phosphorothioate ODNs bind selectively and with high affinity to RNA within cells leading to potent antisense inhibition of RNA translation. The effect that increasing steric bulk of C-5-substituted deoxyuridine analogs has on affinity for RNA and ability to inhibit gene expression is discussed. The relative binding affinity was measured by thermal denaturation (Tm) analysis, and antisense activity was determined by inhibition of SV40 T-antigen (TAg) expression in CV1 cells. The results show that antisense activity is not directly correlated to Tm measurements. In vitro analysis (RNase H cleavage, on-rates, and off-rates) and pre-formed ODN/RNA experiments indicate that RNase H activity and intracellular dissociation appear to be major determinants of the antisense potency of the various substituted ODNs. The results of our analysis point to the unique ability of C-5 propyne dU ODNs to selectively bind to RNA within cells and activate cleavage of RNA by RNase H leading to potent inhibition of gene expression.
Animals↗
Independent medical examinations and the fuzzy politics of disclosure.
The number of third-party independent medical examinations is increasing, and so is the controversy surrounding them. Dorothy Grant of the Medical Society of Nova Scotia provides advice on how physicians should address this potentially contentious issue.
Conflict of Interest↗
Generation of dendritic cell-like antigen-presenting cells in long-term mixed leucocyte culture: phenotypic and functional studies.
The mechanisms contributing to the proliferation and differentiation of antigen-presenting cell (APC) precursors upon antigen stimulation or tissue injury are poorly understood. Herein, we report the induction of a population of dendritic cell-like cells (DLC) with potent antigen-presentation function from unfractionated spleen cells by means of repetitive allostimulation in long-term mixed leucocyte cultures (LT-MLC). Initially, only a few adherent DLC were observed. By 4-6 weeks, however, there were large numbers of DLC which survived persistently. Features of these DLC are closely related to dendritic cells (DC), including (1) dendritic, veiled or spiny-processed morphology; (2) expression of a wide array of leucocyte surface markers including DC-associated or restricted antigens: 33D1, NLDC-145, CD11c (N418), heat-stable antigen (HSA), CD44, B7-1 and B7-2; (3) ability to migrate to draining lymph nodes and white pulp area of spleen; (4) expression of high level of major histocompatability complex (MHC) class II molecules and (5) more potent mixed leucocyte reaction (MLR)-stimulating capacity than peritoneal macrophages and APC-enriched spleen cells. DLC-stimulated MLR was inhibited by monoclonal antibodies (mAbs) to B7-1, B7-2, intracellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), leucocyte-function associated antigen-1 (LFA-1) or very-late activation antigen-4 (VLA-4) by 30-55%. When maintained for more than 2 months, the DLC did not lose their MLR-stimulating activity, but many surface markers were down-regulated except for Mac-2 and VCAM-1, which remained stable or were up-regulated, respectively. In short-term culture, the addition of granulocyte-macrophage colony-stimulating factor (GM-CSF) or interleukin (IL)-2 enhanced proliferation of DLC, while tumour necrosis factor-alpha (TNF-alpha) and IL-4 did not. IL-4 suppressed not only 'spontaneous', but also GM-CSF-enhanced proliferation, suggesting that cytokines play a differential role in DLC proliferation. These results confirm that professional APC can proliferate in response to repetitive antigen stimulation, and their proliferation is differentially regulated by cytokines. A comparison study of DLC with typical DC is being carried out in our laboratory.
Animals↗
The need for effective contrast agents to enhance the performance of MR imaging.
Explore the source record for details and available documents.
Animals↗
MR imaging properties and pharmacokinetics of MnDPDP in healthy volunteers.
PURPOSE: Thirteen male volunteers were studied to evaluate the MR imaging properties and pharmacokinetics of 10 mM mangafodipir trisodium infusion (MnDPDP, Teslascan). MATERIAL AND METHODS: Doses of 5 and 10 mumol/kg b.w. were administered by bolus injection (< 1 min) to 5 subjects, and by infusion (20 min) to 8 subjects, with a 3-week wash-out between doses. Infusion subjects underwent MR imaging. RESULTS: At 1 h after infusion, the plasma concentration of Mn was reduced to approximately 15% of the maximum value. Fifteen to 20% of Mn was recovered in the urine, and 50-60% was recovered in the faeces. The rapid initial plasma clearance of Mn is consistent with both rapid tissue uptake and rapid renal elimination. Increases in signal intensity were apparent on T1-weighted images of the liver, pancreas, spleen, renal cortex and the renal medulla, but not in regions of the brain protected by an intact blood-brain barrier. Increases were seen in the choroid plexus and pituitary. Contrast-related adverse events, only flushing of moderate intensity, occurred in bolus injection subjects. CONCLUSION: At 5 and 10 mumol/kg, mangafodipir produces relatively long-lasting enhancement of several abdominal organs, including the liver, pancreas and kidney.
Adult↗
Metabolism and pharmacokinetics of MnDPDP in man.
PURPOSE: To study the metabolism and pharmacokinetics of mangafodipir trisodium injection, 0.01 mmol/ml (Teslascan), in healthy male volunteers. MATERIAL AND METHODS: Eight volunteers received mangafodipir trisodium as an infusion over 20 min, and 5 received it as an injection (< 1 min). Both groups received 5 and 10 mumol/kg b.w. with a wash-out period of 3 weeks between doses. Metabolites were measured in plasma, total manganese and zinc were measured in plasma and urine and total manganese was measured in faeces. RESULTS: The parent compound MnDPDP (manganese dipyridoxyl diphosphate) and 5 metabolites; MnDPMP (manganese dipyridoxyl monophosphate). MnPLED (manganese dipyridoxyl ethylenediamine) and the corresponding zinc compounds ZnDPDP, ZnDPMP and ZnPLED, were detected in plasma. ZnPLED was the only detectable metabolite 8 h after dosing. The apparent volume of distribution of manganese exceeded the interstitial body fluids. The volume of distribution of the ligand indicated distribution to the extracellular fluid only, with the plasma clearance close to the glomerular filtration rate. The manganese was incompletely excreted during the 4 days after treatment with the major part in faeces and less than 20% of the dose in the urine. CONCLUSION: Dephosphorylation and simultaneous transmetallation with zinc are the main metabolic pathways of MnDPDP in man.
Chromatography, High Pressure Liquid↗
Plasma pharmacokinetics, tissue distribution and excretion of MnDPDP in the rat and dog after intravenous administration.
PURPOSE: To investigate distribution and excretion of mangafodipir (MnDPDP, Teslascan) in the rat and dog. MATERIAL AND METHODS: Formulations of either 14C-MnDPDP or 54MnDPDP were injected intravenously at near clinical doses in rats and dogs. RESULTS: The manganese (Mn) moiety is rapidly removed from plasma with an elimination half-life of less than 25 min in both species, reflecting a rapid distribution to the tissues and an early excretion. The plasma clearance of the DPDP moiety is slower than that of Mn and it appears to distribute into the extracellular fluid. Mn is distributed largely to the liver, pancreas and kidneys, and in pregnant rats, also to foetal liver and bones. No transplacental passage of DPDP could be detected. The metal is mainly excreted by the faecal route, with a small fraction eliminated early in the urine. DPDP is rapidly and essentially completely excreted in the urine, consistent with the glomerular filtration rate. CONCLUSION: The ligand does not appear to facilitate the transport of Mn into any organ except the kidney for subsequent excretion, and it reduces distribution to the heart. The Mn is taken up by those organs indicated for MR imaging, primarily liver and pancreas.
Animals↗