Canine hypoparathyroidism: case report / Hipoparatireoidismo canino: relato de caso

Primary hypoparathyroidism is an uncommon endocrinopathy in dogs, resulting from absolute or relative deficiency in the secretion of parathormone (PTH). The dog presented signs of hypocalcemia, including muscular spasms, tetany and cramps, evolving to tonic-clonic seizures and fever. Emergency therapy for hypocalcemia included glucose physiological solution at 0.45% and calcium gluconate administered intravenously. Diagnosis was confirmed by the presence of hypocalcemia, hyperphosphatemia and a decrease in parathormone (PTH).(AU)

O hipoparatireoidismo primário é uma endocrinopatia incomum em cães, resultante da deficiência absoluta ou relativa na secreção do paratormônio (PTH). O cão apresentava sinais de hipocalcemia, incluindo espasmos musculares, tetania e cãibras que evoluíram para convulsões tônico-clônicas e febre. A terapia de emergência para hipocalcemia incluiu solução glicofisiológica 0,45% e gluconato de cálcio por intravenosa. O diagnóstico foi confirmado pela presença de hipocalcemia, hiperfosfatemia e diminuição do paratormônio (PTH).(AU)

Controlling a vancomycin-resistant enterococci outbreak in a Brazilian teaching hospital.

The purpose of this article was to describe a 2.5-year interventional program designed to control the dissemination after a large hospital outbreak of vancomycin-resistant enterococci (VRE) in a tertiary-care university hospital. A VRE working group was designated to work specifically on controlling VRE intrahospital dissemination after the detection of the first VRE infection at in our hospital in June 2007. The intervention consisted in the interruption of new admissions during a period of 15 days and closure of the index case unit, microbiological surveillance of rectal swabs for VRE, cohorting patients and staff, immediate application of contact precautions, and continuous education. From July 2007 to December 2009, 8,692 rectal swabs were cultured for VRE and 321 (3.7%) were positive. An expressive reduction of the detection of new positive rectal swabs cultures was seen during the year 2009 (1.5%) when compared to 2008 (4.2%) and 2007 (7.2%) (p < 0.005). The annual ratio of VRE per 1,000 admissions reduced from 20.3 in 2007 to 10.07 and 3.82 in 2008 and 2009, respectively (p < 0.001). The continuous microbiologic surveillance for VRE and strict and prompt contact precautions for VRE patients were the fundamental aids in the control of VRE.

Antibodies against the fibrin beta-chain amino-terminus detect active canine venous thrombi.

BACKGROUND: This study was performed to determine whether antibodies against the amino-terminus of the beta-chain of fibrin (anti-beta) could noninvasively distinguish actively enlarging thrombi from thrombi stabilized with anticoagulants. METHODS AND RESULTS: Dogs with unilateral femoral vein thrombi were allocated into three groups: (1) no anticoagulation, (2) intravenous heparin maintained in the "therapeutic" range (0.2 to 0.5 U/mL plasma), and (3) "excess" heparin, maintained at >1.0 U/mL plasma. Thrombolysis was suppressed with tranexamic acid. (111)In-labeled anti-beta was infused, and gamma scans of the legs were performed at regular intervals for 24 hours. Scans were interpreted in a blinded fashion. In addition, for each scan, the number of gamma counts from the femoral area on the thrombosed side was compared with the contralateral side. Clot/blood isotope density was determined postmortem. Leg thrombi in the no-anticoagulation group were 100% detectable, mean (+/-SD) relative count in the thrombosed femoral area was 186% (+/-30%) of the contralateral side, and clot/blood ratio was 14.7 (+/-2.0). Thrombi in the therapeutic heparin group were only 75% detectable, relative counts in the thrombosed femoral areas decreased to 125% (+/-20%), and clot/blood ratio declined to 11.3 (+/-3.5). In the "excess heparin" group, leg thrombi were only 50% detectable, the thrombosed femoral area had relative counts of 118%+/-17%, and the clot/blood ratio fell to 7.8+/-1.9. CONCLUSIONS: Radiolabeled anti-beta noninvasively distinguishes propagating thrombi from those stabilized by anticoagulants. They may be useful for detecting thrombosis clinically as well as for monitoring the efficacy of anticoagulation.

Degree of polymer organization decreases the binding of a monoclonal antibody raised against the beta-chain amino terminus of fibrin.

UNLABELLED: Accurate non-invasive diagnosis of deep venous thrombosis and pulmonary embolism remains an elusive goal. Radiolabeled antibodies specific for the epitope exposed on the beta-chain of fibrin after fibrino-peptide B release (anti-beta) enabled in situ imaging of thrombi in experimental subjects with nuclear medicine techniques. When used in patients anticoagulated for thrombo-embolic disease, however, the antibody was unable to reliably image the thrombi. We postulated that the neoepitope on the beta-chain of fibrin is covered up as fibrin organizes into a polymer network and is therefore exposed to the antibody only during active incorporation of fibrin subunits. We determined the equilibrium binding kinetics of an anti-beta monoclonal antibody to fibrin in various stages of organization. The concentration of exposed epitopes on immobilized fibrin monomers was equal to the molar concentration of fibrin beta-chains. The percentage of beta-chains exposed to the antibodies markedly decreased as the fibrin network was allowed to organize, a process catalyzed by calcium. CONCLUSIONS: The beta-chain amino terminus of fibrin is exposed transiently as subunits are added to the enlarging fibrin network. Anti-beta antibodies bind preferentially to actively enlarging fibrin polymers.

Dextran modification of a Fab'--beta-lactamase conjugate modulated by variable pretreatment of Fab' with amine-blocking reagents.

The physical and pharmacological properties of proteins can be altered by chemical modification with polymers. Preliminary studies showed that attachment of oxidized dextran to the bacterial protein, beta-lactamase (beta L) effectively reduced in vivo immunogenicity in mice with no loss of enzymatic activity. This report describes a general method for differentially dextran modifying the Fab' component of a Fab'--beta-lactamase conjugate by the use of amine-blocking reagents. Methyl acetimidate (MeAcm) and the N-succinimidyl derivative of (methylsulfonyl)ethyl carbonate (NHS-Msc), reagents which can reversibly block primary amines, were used in model studies to modulate the level of available reactive amines on the F(ab')2 fragments of both the anti-carcinoembryonic antigen antibody, ZCE025, and the antitumor-associated glycoprotein-72 antibody, CC49. MeAcm had little or no effect on immunoreactivity and was maximally effective in modulating dextran attachment, while NHS-Msc was much less effective. A comparison of NHS-Msc and MeAcm is described. Treatment of F(ab')2 with 5-300 mM MeAcm prior to dextran treatment showed a proportional decline in the level of dextran attachment as well as intramolecular cross-linking of the protein by the dextran polymers (6 kDa or 33-mer). A conjugate of beta L coupled to MeAcm-treated ZCE025 Fab' [reduced F(ab')2] was constructed under standard conditions using sulfosuccinimidyl N-[(4-carboxycyclohexyl)methyl]maleimide. After dextran modification, this conjugate maintained good immunoreactivity and enzymatic activity. Biodistribution studies in tumor-bearing nude mice of dextranated and nondextranated conjugate showed comparable overall distribution profiles except that the clearance of the dextranated conjugate from both blood and tumor was delayed about 48-72 h.

Altered pharmacokinetic and tumour localization properties of Fab' fragments of a murine monoclonal anti-CEA antibody by covalent modification with low molecular weight dextran.

This paper describes the modification of Fab' fragments of ZCE025, a murine monoclonal antibody recognizing carcinoembryonic antigen (CEA), with oxidized dextran of low molecular weight. This modification altered the in vitro and in vivo characteristics of the Fab'. The dextran conjugated fragments exhibited markedly reduced renal uptake and excretion and the prolonged residence time of the Fab' in the vascular compartment. The result was enhanced tumour localization of the derivative compounds compared with underivatized Fab', even though the process of chemical coordination reduced the immunoreactivity of the molecule. The isoelectric point of the molecule was much lower than the unaltered Fab' and previous research has shown this to reduce markedly its potential for inducing a human anti-mouse antibody (HAMA) response. Thus, the conjugation of Fab' fragments with low molecular weight oxidized dextrans can increase the bioavailability of these fragments for tumour localization, while simultaneously reducing their immunogenic potential and renal accumulation problems.

Pharmacokinetics of 111In-labelled monoclonal antibody ZCE-025 and fragments in tumour-bearing mice.

Radiolabelled anti-tumour antibodies, their fragments and derivatives hold promise for imaging and therapeutics in oncology. A better understanding of the pharmacokinetics of these entities is therefore important for clinical applications and management. In the present study, the in vivo behaviour of 111Indium-labelled monoclonal anti-CEA antibody ZCE-025 and its F(ab')2 and Fab' fragments and a Fab' derivative are compared in the nude mouse-human tumour model. The object of the derivative was to improve the tumour uptake of the fragment yet reduce its high renal uptake while continuing to achieve desirable kinetics in the normal tissues. Uptake of the derivative in the tumour was comparable to that of the intact antibody and exceeded that of the underivatized fragments. Moreover, uptake in non-target tissues was lower with the derivative than with the intact entity. The renal uptake of the derivative was dramatically lower than for the fragments. The modelling data strongly suggest that the derivatives will be advantageous for clinical use compared with the underivatized whole antibodies or their fragments.

Reduction of immunogenicity by covalent modification of murine and rabbit immunoglobulins with oxidized dextrans of low molecular weight.

This communication describes the covalent modification of monoclonal and polyclonal antibodies with oxidized dextrans of low molecular weight to generate conjugates having low immunogenicity in vivo. Conjugation conditions were optimized to generate monomeric, dextran-modified antibodies, free of both high-molecular-weight polymeric aggregates and unmodified antibodies. Conjugates could be prepared with varying levels of dextran substitution. These conjugates retained optimal immunoreactivity as well as in vivo pharmacokinetics and tumor-localization properties. In addition, multiple i.v. administrations of dextran-modified antibodies in animals did not elicit a measurable immune response to either the antibody or the dextran portion of these conjugates.

An automated colorimetric microassay for neuronotrophic factors.

A microassay is described for determining the number of neurons surviving after 24 h in response to added neuronotrophic factors. Neuronal cultures in 96-well microtiter plates are supplied with a yellow tetrazolium derivative, MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide), which is taken up selectively by viable neurons and converted to a blue formazan product. The amount of blue color development can be rapidly quantified using an automatic microplate spectrophotometer. The resulting optical density is directly proportional to the number of viable neurons. The spectrophotometer has been interfaced with a computer allowing a print out of individual absorbance values and calculation of half-maximal (one trophic unit) neuronal survival. The assay has been used for the quantification of the trophic activities of nerve growth factor and ciliary neuronotrophic factor using, respectively, dorsal root and ciliary ganglionic neurons from 8-day chick embryos. Assay parameters were optimized so that about 2000 individual cultures of ganglionic neurons can be set up and analyzed each day, thus allowing the serial titration in duplicate of 80-120 separate samples. The determination of neuronal number and titer calculation steps now requires about 2 min per microplate (96 cultures), a 50-fold reduction in time over existing methods.

Purification of human interleukin 2 to apparent homogeneity and partial characterization of its receptor.

Human interleukin 2, produced by phytohemagglutinin-stimulated peripheral blood lymphocytes cultured in the absence of serum, has been purified to apparent homogeneity with a two-step combination of affinity chromatography with Cibacron blue-Sepharose and gel filtration. The specific activity of the purified IL-2 was 620,000 U/mg of protein, with a total recovery of approximately 13% biological activity. Purified IL-2 stimulated lymphocyte proliferation at a concentration of 4.3 X 10(-10) M. IL-2 was radiolabeled with reductive methylation to a specific activity of 350 microCi/nmol. Binding studies with phytohemagglutinin-activated lymphocytes, known to express receptor for IL-2, identified a single population of approximately 21,000 receptors per cell with an equilibrium dissociation constant of 7.1 X 10(-10) M.

Effect of interferons on protein synthesis in human lymphocytes: enhanced synthesis of eight specific peptides in T cells and activation-dependent inhibition of overall protein synthesis.

Lymphoblastoid and fibroblast IFN inhibited PHA stimulation of overall protein synthesis in human lymphocytes by ca. 30%. Inhibition occurred within the first 6 hr of PHA treatment and was not progressive. DNA synthesis at 48 hr was inhibited to the same extent. Overall protein synthesis in resting lymphocytes was not detectably inhibited by IFN concentrations up to 1000 U/ml. Thus, inhibition of protein synthesis and subsequent reduction of cell proliferation by IFN require certain early events in mitogen activation. Resting lymphocytes were not unresponsive to IFN treatment, however. Two-dimensional electrophoretic analysis of newly synthesized proteins after IFN treatment showed enhanced synthesis of a specific set of eight peptides (I-peptides), which were shown to be synthesized in T lymphocytes. This enhancement was produced by both IFN-alpha and IFN-beta after 4 to 6 hr of exposure and was identical for all lymphocyte donors studied. After growth stimulation, IFN treatment produced no enhancements of additional peptides, although the original eight I-peptides were enhanced as usual. It is concluded that the biochemical activities of the I-peptides, which remain to be determined, cannot inhibit protein synthesis in resting lymphocytes, but may do so after mitogen activation, when the major physiologic restriction of lymphocyte protein synthesis is released. Alternatively, the I-peptides may be unrelated to regulation of protein synthesis but may be involved in viral protection or enhancement of NK activity.

Removal of phytohemagglutinin from conditioned medium by affinity chromatography.

Supernatants of lymphocytes cultured with phytohemagglutinin (PHA-induced conditioned medium) are known to contain residual lectin. Studies with T cells specifically sensitized against a given antigen and maintained in culture by the T cell growth factor in conditioned medium may be hampered by the presence of PHA since the lectin could induce polyclonal activation of T cells. We developed a procedure for removing lectin from conditioned medium by affinity adsorption on porcine thyroglobulin-Sepharose. The affinity method was capable of removing detectable amounts of lectin since the mitogenic capacity for peripheral blood lymphocytes was lost after adsorption. In contrast, thyroglobulin-Sepharose adsorbed CM retained good mitogenic activity and growth-supporting capacity for human cultured T cells.

Cytotoxicity against the K562 erythroleukemia cell line by human natural killer (NK) cells which do not bear free Fc receptors for IgG.

When Fc receptors (FcR) on normal human peripheral blood lymphocytes were induced to modulate by overnight (18 h) incubation in the presence of soluble or particulate immune complexes, the natural killer (NK) activity of the effector lymphocyte suspension, as measured against the K562 erythroleukemia cell line, was significantly, but only partially, inhibited. The NK activity which remained was always strong, and was not significantly inhibited by inclusion of antigen-antibody complexes in the cytotoxicity assay, nor was it further depleted by adsorbing the modulated cells on plastic surfaces coated with immobilized antigen-antibody complexes. Antibody-dependent cell-mediated cytotoxicity (ADCC) against rabbit antibody-sensitized Chang liver cells was totally abrogated following the modulation process, and could not be restored by exposure of modulated effector cells to trypsin, indicating that the FcR had actually been shed and were not merely being blocked with immune complexes. Although freshly isolated peripheral blood lymphocytes active in natural (or "spontaneous") cytotoxicity have been shown to bear FcR, our data indicate that NK activity against the K562 cell line can be effectively mediated by NK cells which have lost their FcR. This supports the concept that NK activity against K562 is independent of FcR, and, therefore, of IgG.

Attempt to alter antigenic structure of normal tissues by treatment with dimethyl-triazeno-imidazole-carboxamide in vivo.

The antigenic structure of normal skin and spleen cells has been investigated following in vivo treatment with the compound DIC. In experiments involving skin grafting in the normal and sensitized host, cross sensitization with a DIC-antigenic lymphoma and 3H-thymidine incorporation by lymphocytes cultured with DIC-treated spleen cells, new antigens on DIC-treated tissues were not demonstrated.