ABSTRACT
Engagement of Fcγ-receptors triggers a range of downstream signalling events resulting in a diverse array of immune functions. As a result, blockade of Fc-mediated function is an important strategy for the control of several autoimmune and inflammatory conditions. We have generated a hexameric-Fc fusion protein (hexameric-Fc) and tested the consequences of multi-valent Fcγ-receptor engagement in in vitro and in vivo systems. In vitro engagement of hexameric-Fc with FcγRs showed complex binding interactions that altered with receptor density and triggered the internalisation and degradation of Fcγ-receptors. This caused a disruption of Fc-binding and phagocytosis. In vivo, in a mouse ITP model we observed a short half-life of hexameric-Fc but were nevertheless able to observe inhibition of platelet phagocytosis several days after hexameric-Fc dosing. In cynomolgus monkeys, we again observed a short half-life, but were able to demonstrate effective FcγR blockade. These findings demonstrate the ability of multi-valent Fc-based therapeutics to interfere with FcγR function and a potential mechanism through which they could have a sustained effect; the internalisation and degradation of FcγRs.
Subject(s)
Immunoglobulin Fc Fragments/metabolism , Receptors, IgG/metabolism , Animals , Blood Platelets/cytology , Blood Platelets/metabolism , Cytokines/metabolism , Disease Models, Animal , HEK293 Cells , Half-Life , Humans , Immunoglobulin Fc Fragments/chemistry , Immunoglobulin Fc Fragments/genetics , Macaca fascicularis , Macrophages/cytology , Macrophages/metabolism , Male , Mice , Mice, Transgenic , Phagocytosis , Purpura, Thrombocytopenic, Idiopathic/metabolism , Purpura, Thrombocytopenic, Idiopathic/pathology , Receptors, IgG/chemistry , Receptors, IgG/genetics , Recombinant Fusion Proteins/biosynthesis , Recombinant Fusion Proteins/isolation & purification , Recombinant Fusion Proteins/pharmacokineticsABSTRACT
Matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOFMS) for the analyses of oligonucleotides has generally been carried out using negative ionisation conditions, usually following ammonium ion-exchange chromatography and the addition of ammonium buffers to the MALDI matrix. The molecular ion region is complex, due to the varying degrees of ammoniation of the phosphate backbone of the oligonucleotide. This gives rise to an overall decrease in sensitivity compared with similar size peptides and can cause ambiguity of assignment of the relative molecular mass of the sample. This study describes the use of H(+) ion exchange resin in situ as the means of removing alkali metal ions from the phosphate backbone of the oligonucleotide. An increase in resolution, sensitivity and identification of the molecular species is reported, with little or no difference in sensitivity observed between positive or negative ionisation spectra. This method is now used for routine screening of synthetic oligonucleotides with a gain in sensitivity of 1-2 orders of magnitude compared with previous methods, and mass assignment errors of +/-0.1% are routinely recorded for externally calibrated data.
Subject(s)
Oligonucleotides/analysis , Ion Exchange Resins , Sensitivity and Specificity , Sequence Analysis, DNA/methods , Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization/methodsSubject(s)
Cat Diseases/etiology , Constipation/veterinary , Hysterectomy/veterinary , Ovariectomy/veterinary , Animals , Cat Diseases/diagnostic imaging , Cat Diseases/pathology , Cats , Colon/diagnostic imaging , Colon/pathology , Colon/physiopathology , Constipation/etiology , Constipation/pathology , Female , Hysterectomy/adverse effects , Ovariectomy/adverse effects , Radiography , Tissue Adhesions/complications , Tissue Adhesions/pathology , Tissue Adhesions/veterinary , Uterine Diseases/complications , Uterine Diseases/pathology , Uterine Diseases/veterinaryABSTRACT
Emphysematous cystitis in man and domestic animals is reviewed. A case of emphysematous cystitis occurring 5 d after standard therapy for urethral obstruction in a non-diabetic male Siamese-cross cat is described. Escherichia coli was isolated, and the cystitis resolved after antibiotic therapy.
Subject(s)
Cat Diseases/drug therapy , Cystitis/veterinary , Emphysema/veterinary , Amoxicillin/therapeutic use , Animals , Cats , Cystitis/drug therapy , Emphysema/drug therapy , Humans , MaleABSTRACT
Two cases of lithium toxicity are reported on in dogs having had lithium hypochlorite chlorinated water as their sole source of drinking water. Clinical signs in one dog included polyuria, polydipsia, loss of body mass; dehydration, diarrhoea and general weakness and in the other case, polyuria, polydipsia, loss of body mass and seizures. Withdrawal of the water resulted in complete recovery.
Subject(s)
Dog Diseases/chemically induced , Lithium Compounds , Lithium/poisoning , Animals , Dogs , FemaleSubject(s)
Dog Diseases/etiology , Ovary/transplantation , Postoperative Complications/veterinary , Animals , Dogs , Female , Gastrointestinal Hemorrhage/etiology , Gastrointestinal Hemorrhage/veterinary , Hyperplasia/etiology , Hyperplasia/veterinary , Ovarian Neoplasms/etiology , Ovarian Neoplasms/veterinary , Ovary/pathology , Postoperative Complications/etiology , Stomach Ulcer/etiology , Stomach Ulcer/veterinary , Transplantation, AutologousABSTRACT
Autotransplantation of the ovary to the portal vein drainage area was performed in 1,130 bitches over a period of 5 years. Complications of this procedure occurred in 41 bitches and included gastric ulceration, recurring pro-oestrus and neoplastic transformation of the transplant.
Subject(s)
Dogs/surgery , Ovary/transplantation , Transplantation, Autologous/veterinary , Animals , Dog Diseases , Female , Postoperative Complications/veterinaryABSTRACT
Chilling the roots of the ultra-chill-sensitive plant Episcia reptans at 5-15° C for 1-50 h produced ultrastructural changes such as mitochondrial swelling, tonoplast discontinuity and sub-cellular deposition of two types of crystalline compounds. One deposit, found by pepsin digestion to be proteinaceous, was associated with the tonoplast and its structure changed with time. The other deposit occurred in the cytoplasm, had a non-variable structure and was not digested by pepsin.
