Characterization of thyroid-stimulating blocking antibodies that appeared during transient hypothyroidism after radioactive iodine therapy.

Hypothyroidism after radioactive iodine (RAI) therapy for Graves' disease can be transient or permanent. The cause for early transient hypothyroidism is unknown. We evaluated 11 patients who developed transient hypothyroidism within 6 months of RAI and 12 who remained euthyroid after RAI. Approximately equal numbers of patients in each group had thyroid-stimulating antibody (TSAb) that increased cyclic adenosine monophosphate (cAMP) levels in Chinese hamster ovary (CHO) cells transfected with the recombinant human thyrotropin receptor (TSHR) (WT cells). Approximately equal numbers of patients from both groups had an increase in TSAb activity post-RAI. All TSAbs had their dominant functional epitope on the N-terminus of the TSHR extracellular domain, requiring residues 90-165 for activity because they, but not TSH, completely lost stimulating activity in a receptor chimera, wherein TSHR residues 90-165 were substituted by equivalent residues of the lutropin/choriogonadotropin receptor (LH/CGR). Although equal numbers of patients in both groups had thyrotropin-binding inhibiting immunoglobulin activity (TBII), as measured by radioreceptor assay before RAI, patients with transient hypothyroidism had a surge in TBII activity and all except one became positive for thyroid-stimulating blocking antibodies (TSBAb), as measured by inhibition of TSH-stimulated cAMP from WT cells. When immunoglobulin G (IgGs) were epitope-mapped using TSHR/LH-CGR chimeras with different substitutions, 8 hypothyroid subjects had TSBAbs directed against residues 90-165 of the TSHR, as well as TSHR residues 261-370. Two had functional epitopes directed at residues 9-89 as well as TSHR residues 261-370. None of the euthyroid control patients developed TSBAbs and their TBII activity decreased post-RAI. When patients with transient hypothyroidism reverted to a euthyroid state, TSAb was still detectable in 5; however, TBII was present in all and TSBAb, although decreased, was still positive in 9. In summary, RAI therapy was associated with a change in thyroid antibody characteristics in most patients. Additionally, patients with a surge in TBII and the appearance of TSBAb developed transient hypothyroidism after RAI.     

Reevaluation of the thyroidal radioactive iodine uptake test, with special reference to reversible primary hypothyroidism with elevated thyroid radioiodine uptake

The clinical significance of the thyroidal radioactive iodine uptake (RAIU) test was reevaluated in patients with various thyroid disorders. Compared with 262 normal subjects or 194 patients with euthyroid diffuse goiter with normal serum TSH levels, RAIU values were significantly higher in 100 patients with latent primary hypothyroidism (serum TSH, 5-40 mU/L). In 126 patients with overt primary hypothyroidism (serum TSH, greater than 40 mU/L), RAIU values were either extremely high (49 patients with reversible hypothyroidism and 10 patients with postpartum hypothyroidism) or low (67 patients with irreversible hypothyroidism). The increase in RAIU values in latent, or reversible overt hypothyroidism was TSH dependent, and there was a good correlation between RAIU values and serum TSH levels (r = 0.6203; P less than 0.001). In overt primary hypothyroidism, spontaneous recovery of thyroid function during iodide restriction alone occurred in 52 of 53 patients with RAIU values above 35%, in only 7 of 23 patients with RAIU values between 10-35%, and in none of 50 patients with RAIU below 10%. Thus, recovery was predicted by high RAIU values (P less than 0.001; prediction rate, 91.4%). Goiter was found in about 80% of the patients with reversible hypothyroidism, compared with only 34% of the patients with irreversible hypothyroidism. Recovery of thyroid function during iodide restriction also occurred in 71% of the patients with latent hypothyroidism. However, RAIU measurements did not predict the prognosis of patients with latent hypothyroidism. We conclude that iodine-induced reversible hypothyroidism is common in our patient population, and RAIU measurements may be helpful in determining the prognosis of patients with overt primary hypothyroidism.     

End-organ protection in hypertension by the novel and selective Rho-kinase inhibitor,SAR407899

AIM: To compare the therapeutic efficacy of SAR407899 with the current standard treatment for hypertension [an angiotensin converting enzyme (ACE)-inhibitor and a calcium channel blocker] and compare the frequency and severity of the hypertension-related end-organ damage.METHODS: Long-term pharmacological characte-rization of SAR407899 has been performed in two animal models of hypertension, of which one is sensitive to ACE-inhibition (LNAME) and the other is insensitive [deoxycorticosterone acetate (DOCA)]. SAR407899 efficiently lowered high blood pressure and significantly reduced late-stage end organ damage as indicated by improved heart, kidney and endothelial function and reduced heart and kidney fibrosis in both models of chronic hypertension.RESULTS: Long term treatment with SAR407899 has been well tolerated and dose-dependently reduced elevated blood pressure in both models with no signs of tachyphylaxia. Blood pressure lowering effects and protective effects on hypertension related end organ damage of SAR407899 were superior to ramipril and amlodipine in the DOCA rat. Typical end-organ damage was significantly reduced in the SAR407899-treated animals. Chronic administration of SAR407899 significantly reduced albuminuria in both models. The beneficial effect of SAR407899 was associated with a reduction in leukocyte/macrophage tissue infiltration. The overall protective effect of SAR407899 was superior or comparable to that of ACE-inhibition or calcium channel blockade. Chronic application of SAR407899 protects against hypertension and hypertension-induced end organ damage, regardless of the pathophysiological mechanism of hypertension.CONCLUSION: Rho-kinases-inhibition by the SAR407899 represents a new therapeutic option for the treatment of hypertension and its complications.     

A novel selective 11beta-hydroxysteroid dehydrogenase type 1 inhibitor prevents human adipogenesis

Glucocorticoid excess increases fat mass, preferentially within omental depots; yet circulating cortisol concentrations are normal in most patients with metabolic syndrome (MS). At a pre-receptor level, 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) activates cortisol from cortisone locally within adipose tissue, and inhibition of 11beta-HSD1 in liver and adipose tissue has been proposed as a novel therapy to treat MS by reducing hepatic glucose output and adiposity. Using a transformed human subcutaneous preadipocyte cell line (Chub-S7) and human primary preadipocytes, we have defined the role of glucocorticoids and 11beta-HSD1 in regulating adipose tissue differentiation. Human cells were differentiated with 1.0 microM cortisol (F), or cortisone (E) with or without 100 nM of a highly selective 11beta-HSD1 inhibitor PF-877423. 11beta-HSD1 mRNA expression increased across adipocyte differentiation (P<0.001, n=4), which was paralleled by an increase in 11beta-HSD1 oxo-reductase activity (from nil on day 0 to 5.9+/-1.9 pmol/mg per h on day 16, P<0.01, n=7). Cortisone enhanced adipocyte differentiation; fatty acid-binding protein 4 expression increased 312-fold (P<0.001) and glycerol-3-phosphate dehydrogenase 47-fold (P<0.001) versus controls. This was abolished by co-incubation with PF-877423. In addition, cellular lipid content decreased significantly. These findings were confirmed in the primary cultures of human subcutaneous preadipocytes. The increase in 11beta-HSD1 mRNA expression and activity is essential for the induction of human adipogenesis. Blocking adipogenesis with a novel and specific 11beta-HSD1 inhibitor may represent a novel approach to treat obesity in patients with MS.     

A novel compound, R-138329, increases plasma HDL cholesterol via inhibition of scavenger receptor BI-mediated selective lipid uptake

High-density lipoprotein (HDL) has a protective effect against atherosclerosis. Therefore, a compound that elevates the plasma HDL cholesterol (HDL-C) levels is expected to be a promising anti-atherosclerotic agent. We discovered a novel compound, R-138329, that increased HDL-C by 41% in normolipidemic hamsters at a dose of 100mg/kg. To investigate the mechanism of action of R-138329, we examined the effect of R-138329 on the clearance of [(3)H]cholesterol ether ([(3)H]COE)-labeled and [(125)I]-labeled HDL in mice. R-138329 delayed the clearance of [(3)H]COE-labeled HDL and reduced accumulation of tracer HDL in the liver, whereas the clearance of [(125)I]-labeled HDL particles was unaffected by the compound. In vitro analysis showed that R-154716, a metabolite of R-138329, dramatically inhibited the uptake of [(3)H]COE-labeled HDL in McA-RH 7777 rat hepatoma cells. Furthermore, 100 nM of R-154716 completely inhibited [(3)H]COE-labeled HDL uptake induced by overexpression of scavenger receptor BI (SR-BI) in HEK293 cells. Taken together, these findings suggest that the mechanism by which R-138329 elevates HDL-C in vivo is principally involved in the inhibition of SR-BI-mediated selective lipid uptake in the liver.     

A case of takotsubo cardiomyopathy precipitated by lumiracoxib, a selective COX-2 inhibitor

Considerable controversy exists regarding the cardiovascular safety of COX-2 inhibitors, both in patients with and without established cardiovascular disease. Currently, the major focus is on thrombotic complications presenting as myocardial infarction. I n this report, we present a case of takotsubo cardiomyopathy, also known as the apical ballooning syndrome, precipitated by the use of lumiracoxib. We are concerned that this might be the first case of COX-2 inhibitor-induced apical ballooning syndrome and that more may follow.     

A selective NFkappaB inhibitor, DHMEQ, reduced atherosclerosis in ApoE-deficient mice

BACKGROUND AND PURPOSE: Atherosclerosis is a chronic inflammatory process, and anti-inflammatory agents potentially inhibit the development of atherosclerosis. We tested whether a novel NFkappaB inhibitor reduces atherosclerosis. METHODS: Dehydroxymethylepoxyquinomicin (10 mg/kg) or vehicle (chloromethyl cellulose) was injected intraperitoneally into apoE-deficient mice three times a week for 16 weeks. The entire aorta was excised and atherosclerotic area was determined at 4 and 16 weeks. Serum levels of cholesterol, triglyceride, TNF-alpha and adiponectin were also measured. RESULTS: The atherosclerotic area was significantly smaller in mice treated with dehydroxymethyl-epoxyquinomicin both at 4 and 16 weeks. There was no significant difference in body weight or serum levels of cholesterol, triglyceride, and adiponectin. CONCLUSIONS: A new NFkappaB inhibitor, dehydroxymethylepoxyquinomicin, reduced atherosclerosis without affecting plasma lipid levels in apoE-deficient mice.     

Blockade of the MEK/ERK signalling cascade by AS703026, a novel selective MEK1/2 inhibitor,induces pleiotropic anti‐myeloma activity in vitro and in vivo

This study investigated the cytotoxicity and mechanism of action of AS703026, a novel, selective, orally bioavailable MEK1/2 inhibitor, in human multiple myeloma (MM). AS703026 inhibited growth and survival of MM cells and cytokine‐induced osteoclast differentiation more potently (9‐ to 10‐fold) than AZD6244. Inhibition of proliferation induced by AS703026 was mediated by G₀‐G₁ cell cycle arrest and was accompanied by reduction of MAF oncogene expression. AS703026 further induced apoptosis via caspase 3 and Poly ADP ribose polymerase (PARP) cleavage in MM cells, both in the presence or absence of bone marrow stromal cells (BMSCs). Importantly, AS703026 sensitized MM cells to a broad spectrum of conventional (dexamethasone, melphalan), novel or emerging (lenalidomide, perifosine, bortezomib, rapamycin) anti‐MM therapies. Significant tumour growth reduction in AS703026‐ vs. vehicle‐treated mice bearing H929 MM xenograft tumours correlated with downregulated pERK1/2, induced PARP cleavage, and decreased microvessels in vivo. Moreover, AS703026 (<200 nmol/l) was cytotoxic against the majority of tumour cells tested from patients with relapsed and refractory MM (84%), regardless of mutational status of RAS and BRAF genes. Importantly, BMSC‐induced viability of MM patient cells was similarly blocked within the same dose range. Our results therefore support clinical evaluation of AS703026, alone or in combination with other anti‐MM agents, to improve patient outcome.     

A novel inhibitor of focal adhesion signaling induces caspase-independent cell death in diffuse large B-cell lymphoma

Focal adhesion (FA) proteins have been associated with transformation, migration, metastasis, and poor outcome in many neoplasias. We previously showed that these proteins were inhibited by E7123, a new celecoxib derivative with antitumor activity, in acute myeloid leukemia. However, little is known about FAs in diffuse large B cell lymphoma (DLBCL). This paper aimed to determine whether E7123 was effective against DLBCL and whether FAs were involved in its action. We evaluated the cytotoxicity and mechanism of action of E7123 and celecoxib in DLBCL cell lines. We also assessed the E7123 in vivo activity in a DLBCL xenograft model and studied FA signaling in primary DLBCL patient samples. We found that E7123 showed higher antitumor effect than celecoxib against DLBCL cells. Its mechanism of action involved deregulation of FA, AKT, and Mcl-1 proteins, a pathway that is activated in some patient samples, apoptosis-inducing factor release and induction of caspase-independent cell death. Moreover, E7123 showed suppression of in vivo tumor growth. These findings indicate that E7123 is effective against DLBCL in vitro and in vivo, with a mechanism of action that differs from that of most current therapies for this malignancy. Our results support further preclinical evaluation of E7123.     

AZD1152, a novel and selective aurora B kinase inhibitor, induces growth arrest, apoptosis, and sensitization for tubulin depolymerizing agent or topoisomerase II inhibitor in human acute leukemia cells in vitro and in vivo

Aurora kinases play an important role in chromosome alignment, segregation, and cytokinesis during mitosis. We have recently shown that hematopoietic malignant cells including those from acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL) aberrantly expressed Aurora A and B kinases, and ZM447439, a potent inhibitor of Aurora kinases, effectively induced growth arrest and apoptosis of a variety of leukemia cells. The present study explored the effect of AZD1152, a highly selective inhibitor of Aurora B kinase, on various types of human leukemia cells. AZD1152 inhibited the proliferation of AML lines (HL-60, NB4, MOLM13), ALL line (PALL-2), biphenotypic leukemia (MV4-11), acute eosinophilic leukemia (EOL-1), and the blast crisis of chronic myeloid leukemia K562 cells with an IC50 ranging from 3 nM to 40 nM, as measured by thymidine uptake on day 2 of culture. These cells had 4N/8N DNA content followed by apoptosis, as measured by cell-cycle analysis and annexin V staining, respectively. Of note, AZD1152 synergistically enhanced the antiproliferative activity of vincristine, a tubulin depolymerizing agent, and daunorubicin, a topoisomerase II inhibitor, against the MOLM13 and PALL-2 cells in vitro. Furthermore, AZD1152 potentiated the action of vincristine and daunorubicin in a MOLM13 murine xenograft model. Taken together, AZD1152 is a promising new agent for treatment of individuals with leukemia. The combined administration of AZD1152 and conventional chemotherapeutic agent to patients with leukemia warrants further investigation.     

A selective ROCK inhibitor, Y27632, prevents dimethylnitrosamine-induced hepatic fibrosis in rats

BACKGROUND: p160ROCK is a direct Rho target which mediates Rho-induced assembly of focal adhesions and stress fibers. We previously reported that Rho signaling pathways are involved in the activation of hepatic stellate cells (HSC) in vitro. The aim of the present study was to test the hypothesis that an inhibitor specific for p160ROCK (Y27632) could prevent experimental hepatic fibrosis induced by dimethylnitrosamine (DMN) in rats. METHODS: Y27632 was given orally at 30 mg/kg daily for 4 weeks after the first injection of DMN. The degree of fibrosis was evaluated by image analysis and also by measurements of collagen and hydroxyproline content in the liver. The expression of alpha-smooth muscle actin (alpha-SMA) in the liver and in the primary cultured HSC was also evaluated. Semi-quantitative RT-PCR was performed to evaluate the expression of type I collagen mRNA in the liver. RESULTS: Y27632 treatment significantly decreased the occurrence of DMN-induced hepatic fibrosis and reduced the collagen and hydroxyproline content and alpha-SMA expression in the liver. The expression of alpha-SMA in HSC was also suppressed in vitro. CONCLUSIONS: These findings indicate that inhibitors of the Rho-ROCK pathway might be useful therapeutically in hepatic fibrosis.     

Thyrotoxicosis, then hypothyroidism caused by iodine overload (amiodarone) associated with neuropathy. Failure of plasma exchange

A 54-year-old woman, with no previously documented thyroid disease, treated with amiodarone (200 mg/day, five days a week for 33 months) for paroxysmal tachyarrhythmia complicating mitral stenosis, suddenly developed extremely severe thyrotoxicosis. After therapeutic failures with carbimazole and propylthyrouracil (PTU) associated with beta-blockers, she was transferred to intensive care for plasma exchange (PE). Two PE were performed, temporarily aggravating the cardiovascular status of the patient, with no secondary improvement. The quantity of T3 removed was very small, about 1,000 ng per exchange. On the 14th day PTU had to be discontinued (toxic thrombopenia) and only symptomatic treatment was maintained (assisted ventilation, digitalis, hyperalimentation). In the 4th month, while the patient had a high total serum iodine, hypothyroidism developed due to partial block of the organification of the iodine with high TSH and fixation; this state also lasted 4 months. Spontaneous recovery was observed after 8 months. In addition a severe peripheral neuropathy was observed during the hyperthyroid phase confirmed by electromyography, distinct from the signs of thyrotoxic myopathy. This gradually regressed over 7 months and may be attributed to amiodarone therapy. The association of these two successive types of thyroid disorder due to amiodarone is an exceptionally rare phenomenon. Severe thyrotoxicosis generally requires long-term symptomatic therapy, its natural course being towards spontaneous regression. PE are ineffective on the circulating hormonal levels and were dangerous because of the underlying cardiac disease. The development of hypothyroidism at the 4th month is explained by the persistent iodine overload, and therefore prolonged surveillance after withdrawal of therapy is advised. The neurological complication of amiodarone was quite distinct from the hyperthyroid myopathy.     

Tecadenoson: a novel, selective A1 adenosine receptor agonist

Tecadenoson is a novel selective A1 adenosine receptor agonist that is currently being evaluated for the conversion of paroxysmal supraventricular tachycardia (PSVT) to sinus rhythm. By selectively targeting the A1 receptor, tecadenoson may be associated with fewer adverse effects such as flushing, dyspnea, chest discomfort, and hypotension than adenosine, which is a nonselective agonist of all 4 adenosine receptors. Based on the results of phase I and phase II clinical trials, tecadenoson appears to be an effective agent for producing rapid and sustained conversion of PSVT to sinus rhythm. Additionally, the adverse effects that are typically attributed to adenosine's nonselective stimulation of the A2A, A2B, and A3 receptors appear to occur less frequently with the use of tecadenoson. Tecadenoson also appears to be associated with a lower incidence of atrial fibrillation following conversion of PSVT compared with the rates that have been associated with adenosine in the literature. A randomized, prospective trial will need to be conducted in the future to appropriately compare the safety and efficacy of tecadenoson and adenosine.     

Ivabradine--the first selective and specific I(f) inhibitor, novel preparation for treatment of stable angina

Results of large epidemiological studies allowed to establish that heart rate (HR) is an independent risk factor, elevating rates of total, cardiovascular and sudden mortality. Ivabradine bounds specifically with f channels of sinus node cells providing HR lowering. In experiments with the use of the method of registration of transmembrane currents in cells of sinoatrial node it was revealed that Ivabradine blocks f-channels in a dose-dependent manner. Due to specific action on sinus node and selective suppression of I(f)-currents ivabradine causes dose dependent decrease of HR both at rest and maximal physical exercise without changes of mean blood pressure. It was shown in 3 large clinical studies that Ivabradine together with favorable tolerability profile possesses pronounced antianginal and anti-ischemic efficacy which is at least the same as efficacy of currently available drugs for the treatment of angina beta-adrenoblockers and calcium antagonists. Firstly this confirms clinical significance of concept of specific and selective inhibition of I(f) ionic current in the treatment of patients with ischemic heart disease and stable angina. Secondly this allows to consider the preparation as alternative to available antianginal drugs in case of the presence of contraindications to them or development of side effects at the background of standard therapy.     

Pharmacology and gastrointestinal safety of lumiracoxib, a novel cyclooxygenase-2 selective inhibitor: An integrated study.

BACKGROUND AND AIMS: Lumiracoxib is a structurally novel, acidic selective inhibitor of cyclooxygenase (COX)-2. We coordinated existing methodologies in a single study to evaluate potency, selectivity, and effect on the human gastrointestinal tract. METHODS: Twenty four healthy subjects (aged 18-45 years, 12 female) received high dose lumiracoxib (800 mg every day), standard dose naproxen (500 mg twice a day), or placebo for 8 days in a double-blind randomized crossover study. At the start and end of each dosing period, COX-2 selectivity was assessed by ex vivo serum thromboxane B(2) (COX-1) and lipopolysaccharide stimulated prostaglandin (PG) E(2) (COX-2), mucosal injury by endoscopy, and small and large bowel permeability by 0- to 5-hour and 5- to 24-hour (51)Cr-EDTA absorption. Plasma lumiracoxib was measured 2 hours after dosing on day 8 and vortex-stimulated ex vivo gastric mucosal PGE(2) synthesis at the end of each treatment period by enzyme immunoassay. RESULTS: Lumiracoxib was well absorbed and demonstrated similar potency to naproxen as a COX-2 inhibitor (77% and 66% inhibition, respectively, vs. placebo), but it differed in being more selective (24% and 97% inhibition of thromboxane B(2) vs. placebo). Gastric PGE(2) was reduced by 69% by naproxen (P < 0.001 vs. placebo) and 29% by lumiracoxib (P < 0.01 vs. placebo and naproxen). No subjects developed gastroduodenal erosions on lumiracoxib (vs. 75% on naproxen and 12.5% on placebo). (51)Cr-EDTA absorption increased significantly with naproxen but not lumiracoxib. CONCLUSIONS: Lumiracoxib is a potent selective inhibitor of COX-2 that causes little or no endoscopically detected stomach or duodenal injury or changes in bowel permeability.     

Biochemical and pharmacological characterization of ICI 186,756: a novel, potent, and selective inhibitor of human neutrophil elastase

ICI 186,756 is a representative of a new chemical class of synthetic inhibitors of human neutrophil elastase (HNE). This compound demonstrated competitive inhibition of HNE with a Ki of 3.6 +/- 0.8 x 10(-9) mol/L. The selectivity of ICI 186,756 for HNE versus a variety of enzymes ranged from a minimum of 870-fold to greater than 640,000. The compound effectively inhibited hydrolysis of bovine ligamentum nuchae elastin by HNE. Pretreatment of hamsters with ICI 186,756 up to 2 h before intratracheal administration of HNE inhibited enzyme-induced increases in lung weight, total lavageable red cells, and total lavageable white cells measured 24 h after HNE administration. In contrast, similar lung effects produced by intratracheal administration of porcine pancreatic elastase (PPE) were not inhibited by ICI 186,756. Treatment of hamsters with 43 mumol/kg (sc) of ICI 186,756 for 14 or 28 days modulated the increases in alveolar diameter produced by both PPE and HNE, respectively. It is concluded that ICI 186,756 is a potent, competitive, and selective inhibitor of HNE that may be useful in understanding the role of this enzyme in animal models of various diseases. Furthermore, the maintenance or progression of emphysema-like lesions induced in hamsters by PPE do not appear to be due to the persistence of that enzyme within the lung.