Chronic exposure to cocaine binging predisposes to an accelerated course of dilated cardiomyopathy in conscious dogs following rapid ventricular pacing.

Despite extensive study, the extent to which cocaine use predisposes to cardiac injury remains unknown. We hypothesized that chronic cocaine binging would increase susceptibility to a subsequent cardiac insult, even in the absence of demonstrable effects on baseline hemodynamics. We studied progression of dilated cardiomyopathy (DCM) induced by rapid ventricular pacing (240 beats per minute) in five conscious, chronically instrumented dogs, after exposure to repetitive cocaine binging (COC) in the form of four consecutive 1 mg/kg i.

Coronary blood flow responses are impaired independent of NO and endothelial function in conscious dogs with dilated cardiomyopathy.

Background: Dilated cardiomyopathy (DCM) is characterized by nitric oxide (NO) deficiency and endothelial dysfunction. Whether endothelium-independent vasodilation is preserved, particularly in the coronary circulation, remains controversial.

Methods And Results: We studied systemic and coronary flow responses to the endothelium-dependent agonist, acetylcholine, the cGMP-dependent NO-donor, nitroglycerin, the predominantly endothelium-independent agonist, adenosine, the beta-adrenergic cAMP-dependent agonist, isoproterenol, and the calcium channel antagonist, nicardipine, in conscious dogs with pacing-induced DCM.

Recombinant glucagon-like peptide-1 increases myocardial glucose uptake and improves left ventricular performance in conscious dogs with pacing-induced dilated cardiomyopathy.

Background: The failing heart demonstrates a preference for glucose as its metabolic substrate. Whether enhancing myocardial glucose uptake favorably influences left ventricular (LV) contractile performance in heart failure remains uncertain. Glucagon-like peptide-1 (GLP-1) is a naturally occurring incretin with potent insulinotropic effects the action of which is attenuated when glucose levels fall below 4 mmol.

Role of eye muscle antibody measurement in diagnosis of thyroid-associated ophthalmopathy: a laboratory update.

Objective: To review the current role of measurement of serum eye muscle antibodies in thyroid-associated ophthalmopathy (TAO).

Methods: We conducted laboratory studies to determine the prevalences of serum autoantibodies reactive with eye muscle antigens in patients with active and inactive TAO, Graves' hyperthyroidism, and Hashimoto's thyroiditis as well as in normal subjects.

Results: The two antigens most often recognized in immunoblotting with crude human or porcine eye muscle membranes by serum autoantibodies in patients with TAO are eye muscle membrane proteins of 55 and 64 kd.

The development of myocardial insulin resistance in conscious dogs with advanced dilated cardiomyopathy.

Background: The failing heart demonstrates a preference for glucose as its metabolic substrate. Advanced, severe DCM is characterized by depletion of adenosine triphosphate (ATP) stores, which may be a consequence of impaired insulin mediated glucose uptake and oxidation at a time when the myocardium prefers glucose as its substrate. We examined the time course and magnitude of myocardial insulin resistance during the evolution of dilated cardiomyopathy.

Quantitative reverse transcription-polymerase chain reaction of GABA(A) alpha1, beta1 and gamma2S subunits in epileptic rats following photothrombotic infarction of neocortex.

Photothrombotic brain infarction can result in altered expression of cortical GABA(A) receptors and in epileptic seizures. We sought to determine whether infarct size and/or epileptic seizures resulted in a differential expression of cortical GABA(A) receptor subunit mRNA in adult rats. A reverse transcription-polymerase chain reaction (RT-PCR) was used with internal standards for GABA(A) receptor subunits to quantify alpha(1), beta(1), and gamma(2S) subunit mRNA expression in cortex ipsilateral and contralateral to left cerebral infarcts in small or large infarct/nonepileptic cohorts, a large infarct/epileptic cohort, and a young adult control cohort.

Catecholamine stimulation is associated with impaired myocardial O(2) utilization in heart failure.

Objectives: To investigate the effect of alpha,beta(1) and beta(2) adrenergic receptor (AR) stimulation on coronary hemodynamics, myocardial oxygen consumption (M(v)O(2)) and metabolic substrate preference in advanced dilated cardiomyopathy (DCM).

Methods: We studied 19 conscious, instrumented dogs with pacing-induced DCM. We evaluated systemic, coronary hemodynamics and M(v)O(2) in response to norepinephrine (NOR, 0.

Mechanisms whereby rapid RV pacing causes LV dysfunction: perfusion-contraction matching and NO.

Incessant tachycardia induces dilated cardiomyopathy in humans and experimental models; mechanisms are incompletely understood. We hypothesized that excessive chronotropic demands require compensatory contractility reductions to balance metabolic requirements. We studied 24 conscious dogs during rapid right ventricular (RV) pacing over 4 wk.

Autoantibodies reactive with extracellular matrix proteins in patients with thyroid-associated ophthalmopathy.

Autoantibodies reacting with extracellular matrix proteins have been extensively studied in various autoimmune connective tissue diseases. Because of the possibility that such antibodies may play a role in orbital connective tissue inflammation in thyroid-associated ophthalmopathy (TAO), we studied the humoral immune response against specific extracellular matrix (ECM) proteins, namely: collagen types I, III, IV, V (CI, CIII, CIV, CV), fibronectin (FN), and laminin (LM). Anti-ECM antibodies of immunoglobulin G (IgG), IgA, and IgM classes were determined by enzyme linked immunosorbent assay (ELISA).

A 63 kDa skeletal muscle protein associated with eye muscle inflammation in Graves' disease is identified as the calcium binding protein calsequestrin.

It is generally accepted that thyroid-associated ophthalmopathy (TAO) is an autoimmune disease of the eye muscle (EM) and the surrounding orbital connective tissue in which circulating antibodies play an important role. Antibodies against EM membrane proteins of 63-67kDa mol. wt.

T cell interactions with extracellular matrix proteins in patients with thyroid-associated ophthalmopathy.

Although thyroid-associated ophthalmopathy (TAO) is now generally accepted as an autoimmune inflammatory disorder of the extraocular muscles and the orbital connective tissue, its aetiopathogenesis remains poorly understood. Recent data indicate that impaired interactions between T cells and extracellular matrix (ECM) proteins may play an important role in development and maintaining of an inflammatory process. We report here results of the study focusing on interactions between T lymphocytes and collagen-I (Coll-I), collagen-IV (Coll-IV), fibronectin (FN), laminin (LM) in patients with TAO.

Reevaluation of the prevalences of serum autoantibodies reactive with "64-kd eye muscle proteins" in patients with thyroid-associated ophthalmopathy.

Serum autoantibodies reactive with eye muscle proteins of "64 kilodaltons (kd)" are frequently found in patients with Graves' hyperthyroidism and thyroid-associated ophthalmopathy (TAO). Earlier, we cloned a 64-kd protein that was identified as calsequestrin, a calcium-binding protein localized in the sarcoplasmic reticulum of striated muscle and extensively studied another cloned 64-kd protein, called 1D, which is expressed in thyroid and eye muscle, and some other tissues. Using a monoclonal antibody against calsequestrin, a polyclonal antibody against 1D and a TAO patient serum reactive with the "64-kd protein," as probes, we performed Western blots of porcine eye muscle membrane.

The 64-kilodalton eye muscle protein is the flavoprotein subunit of mitochondrial succinate dehydrogenase: the corresponding serum antibodies are good markers of an immune-mediated damage to the eye muscle in patients with Graves' hyperthyroidism.

Thyroid-associated ophthalmopathy (TAO) is a progressive eye disorder associated with thyroid autoimmunity, particularly Graves' hyperthyroidism, which is generally considered to have an autoimmune etiology. Eye muscle membrane proteins reportedly of 55 and 64 kDa are the best markers of the ophthalmopathy. The main focus of our recent studies has been to purify the pertinent proteins from porcine eye muscle membranes and characterize them.

Antibodies against striated muscle, connective tissue and nuclear antigens in patients with thyroid-associated ophthalmopathy: should Graves' disease be considered a collagen disorder?

The identity and subcellular localization of the principal extraocular muscle (EOM) antigens and prevalences of the corresponding serum autoantibodies in thyroid-associated ophthalmopathy (TAO) need to be clarified. We have used porcine eye muscle tissue, which expresses all autoantigens identified in human tissue, as substrate in an indirect immunofluorescence assay. Several different patterns of antibody binding to EOM tissue antigens were observed with sera from patients with TAO namely, membrane, cytoplasmic, interstitial (endomysial) and nuclear.

Serum antibodies reactive with eye muscle antigens and the TSH receptor in a euthyroid subject who developed ophthalmopathy and Graves' hyperthyroidism.

Serum antibodies reactive with eye muscle autoantigens, in particular a 64-kDa protein that is also expressed in the thyroid, and the TSH receptor, are associated with the ophthalmopathy that occurs in about 50% of patients with Graves' hyperthyroidism. We have had the opportunity to study a euthyroid, apparently normal, 35-year-old woman with a family history of thyroid autoimmunity and "colitis" but no clinical or biochemical evidence for thyroid disease or ophthalmopathy, who developed Graves' hyperthyroidism and ophthalmopathy together 18 months later. Serum taken when the patient was first seen was positive for antibodies reactive with (i) 9 different eye muscle proteins ranging in size from 15 to 130 kDa, notably those of 64, 55, and 50 kDa, by immunoblotting with eye muscle membranes, (ii) eye muscle and Müller's muscle cell membrane antigens in antibody-dependent cell-mediated cytotoxicity (ADCC), (iii) an eye muscle cytoplasmic antigen in indirect immunofluorescence, and (iv) the TSH receptor as measured in a radioreceptor binding inhibition assay.

Antibody-dependent cell-mediated cytotoxicity against orbital target cells in thyroid-associated ophthalmopathy and related disorders; close relationship between serum cytotoxic antibodies and parameters of eye muscle dysfunction.

We have carried out tests for antibody-dependent cell-mediated cytotoxicity (ADCC) against extra ocular muscle (EOM), Müller's muscle, orbital fibroblasts and skeletal muscle in patients with thyroid-associated ophthalmopathy (TAO) and related eye disorders. Cytotoxicity was measured as lactate dehydrogenase (LDH) release and results expressed as % cytotoxicity. Tests were positive, with EOM cells, in 65% of patients with TAO, 75% with ocular myopathy, a variant of TAO in which periorbital inflammation is minimal, 50% with euthyroid Graves' disease defined as ophthalmopathy associated with subclinical thyroiditis and in 50% of patients with stable lid lag and retraction but no other signs of progressive ophthalmopathy, but in only 13% of patients with Graves' hyperthyroidism without ophthalmopathy, 10% with Hashimoto's thyroiditis and 14% of patients with other thyroid disorders.

Failure to demonstrate cell-mediated immunity to orbital tissue antigens and epitopic fragments of a 64 kDa protein in the majority of patients with thyroid-associated ophthalmopathy.

We have studied a possible role of T cell sensitization to eye muscle antigens in patients with thyroid-associated ophthalmology (TAO). Peripheral blood mononuclear cell (PBMC) proliferation in response to crude porcine orbital tissue antigens, partially purified porcine eye muscle membrane proteins and predicted epitopic fragments of the recombinant 64 kDa protein 1D, was determined in patients with TAO and thyroid autoimmunity without eye disease. When membrane and cytosol fractions were used as antigen PBMC from 43% of patients with TAO but only 12.

New assays for the measurement of serum antibodies reactive with eye muscle membrane antigens confirm their significance in thyroid-associated ophthalmopathy.

Although sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blotting are widely used to detect serum antibodies in patients with autoimmune disorders, this procedure unfolds and denatures proteins and may alter antibody binding sites. We have used nondenaturing methods for the purification of a 64-kDa eye muscle (EM) membrane antigen associated with thyroid-associated ophthalmopathy (TAO). Pig EM membrane proteins were prepared from crude homogenates by high-speed centrifugation and solubilized by hand homogenization.

Native gel electrophoresis and isoelectric focusing of a 64-kilodalton eye muscle protein shows that it is an important target for serum autoantibodies in patients with thyroid-associated ophthalmopathy and not expressed in other skeletal muscle.

Although sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blotting are widely used to detect serum antibodies in patients with autoimmune disorders, this procedure unfolds and denatures proteins and may alter antibody-binding sites. We have used a gentle protocol for the preparation and purification of a 64-kilodalton (kDa) eye muscle (EM) membrane antigen associated with thyroid-associated ophthalmopathy (TAO) for use as antigen in immunoblotting. Pig EM membrane proteins were prepared from crude homogenates by high speed centrifugation and solubilized by hand homogenization.

Upper eyelid retraction in the absence of other evidence for progressive ophthalmopathy is associated with eye muscle autoantibodies.

We have studied 25 clinically euthyroid patients with eyelid lag and retraction referred to thyroid/eye clinic for clinical and orbital imaging evidence of extraocular eye muscle (EM) involvement, evidence of progressive ophthalmopathy and serum antibodies reactive with EM membrane antigens in immunoblotting. Fourteen patients had Graves' hyperthyroidism, 5 had Hashimoto's thyroiditis, and 6 had euthyroid Graves' disease. By carrying out orbital imaging we showed EM abnormalities in 10 of 23 patients (43%).

Serum antibodies reactive with eye muscle membrane antigens are detected in patients with nonspecific orbital inflammation.

Purpose: Nonspecific orbital inflammation, also called "orbital pseudotumor," has many of the features of thyroid-associated ophthalmopathy, especially when localized to the eye muscle. The purpose of this study is to test for circulating autoantibodies against eye muscle antigens and features of possible thyroid autoimmunity in patients with nonspecific orbital inflammation.

Methods: The authors studied eight patients with diffuse or localized nonspecific orbital inflammation.

Antibodies against 1D, a recombinant 64-kDa membrane protein, are associated with ophthalmopathy in patients with thyroid autoimmunity.

We have tested for serum antibodies reactive with 1D, a recombinant 65-kDa human thyroid protein which is also expressed in eye muscle, in patients with thyroid autoimmunity and ophthalmopathy by immunofluorescence and SDS-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blotting. We also measured antibodies to a 64-kDa pig eye muscle membrane protein which is identified by SDS-PAGE and Western blotting, correlating the two reactivities. While antibodies to 1D, expressed in Chinese hamster ovary (CHO) cell membrane, were detected in approximately 40% of patients with ophthalmopathy, in both tests the greatest prevalence, by immunofluorescence, 73%, was demonstrated in patients with Graves' hyperthyroidism without clinically evident eye disease, although only 50% of these patients were positive in immunoblotting.

Extrarenal clearance of oxalate increases with progression of renal failure in the rat.

Oxalic acid is an end product of metabolism, and no significant degradation of oxalate occurs in mammals. The sole route of oxalate excretion is believed to be via the kidney. The extrarenal clearance of oxalate in control rats (N = 16) and in 5/6 nephrectomized rats (N = 25) with renal insufficiency was investigated.

Effect of vitamin B6 supplementation on plasma oxalate and oxalate removal rate in hemodialysis patients.

Whether pyridoxine (B6) supplements decrease plasma oxalate concentrations in patients on maintenance dialysis is unresolved. The effect of two dose levels of B6, 0.59 mmol/day (100 mg/day) over 6 months and 4.