Efficacy of the tubercidin antileishmania action associated with an inhibitor of the nucleoside transport

Tubercidin (TUB) is an adenosine analog with potent antiparasite action, unfortunately associated with severe host toxicity. Prevention of TUB toxicity can be reached associating nitrobenzylthioinosine (NBMPR), an inhibitor of the purine nucleoside transport, specifically target to the mammal cells. It was demonstrated that this nucleoside transport inhibitor has no significant effect in the in vitro uptake of TUB by Schistosoma mansoni and Trypanosoma gambiense. Seeking to evaluate if the association of these compounds is also effective against leishmania, we analyzed the TUB-NBMPR combined treatment in in vitro cultures of promastigote forms of Leishmania (L.) amazonensis, Leishmania (L.) chagasi, Leishmania (L.) major, and Leishmania (V.) braziliensis as well as in cultures of amastigote forms of L. (L.) amazonensis, mice macrophages infected with L. (L.) amazonensis, and in vivo tests in BALB/c mice infected with L. (L.) amazonensis. We demonstrated that TUB-NBMPR combined treatment can be effective against leishmania cells protecting mammalian cells from TUB toxicity.

Acromegaly: correlation between expression of somatostatin receptor subtypes and response to octreotide-lar treatment

About one-third of acromegalics are resistant to the clinically available somatostatin analogs (SA). The resistance is related to density reduction or different expression of somatostatin receptor subtypes (SSTR). This study analyzes SSTR`s expression in somatotrophinomas, comparing to SA response, hormonal levels, and tumor volume. We analyzed 39 somatotrophinomas; 49% were treated with SA. The most expressed SSTR was SSTR5, SSTR3, SSTR2, SSTR1, and SSTR4, respectively. SSTR1 and SSTR2 had higher expression in patients that had normalized GH and IGF-I. SSTR3 was more expressed in patients with tumor reduction. There was a positive correlation between the percentage of tumor reduction and SSTR1, SSTR2 and SSTR3 expression. Also, a positive correlation between SSTR2 mRNA expression and the immunohistochemical reactivity of SSTR2 was found. Our study confirmed the association between the SA response to GH and IGF-I and the SSTR2. Additionally, this finding was also demonstrated in relation to SSTR1.

A Consensus on Criteria for Cure of Acromegaly

Objective: The Acromegaly Consensus Group met in April 2009 to revisit the guidelines on criteria for cure as defined in 2000. Participants: Participants included 74 neurosurgeons and endocrinologists with extensive experience of treating acromegaly. Evidence/Consensus Process: Relevant assays, biochemical measures, clinical outcomes, and definition of disease control were discussed, based on the available published evidence, and the strength of consensus statements was rated. Conclusions: Criteria to define active acromegaly and disease control were agreed, and several significant changes were made to the 2000 guidelines. Appropriate methods of measuring and achieving disease control were summarized. (J Clin Endocrinol Metab 95: 3141-3148, 2010)

Optimizing Medical Therapy of Acromegaly: Beneficial Effects of Cabergoline in Patients Uncontrolled with Long-Acting Release Octreotide

Background: Previous data indicate a beneficial effect of cabergoline (CAB) association to somatostatin analogs (SA) in acromegalics resistant to SA monotherapy. Objective: To assess the efficacy of CAB association on acromegalics with high IGF-I on stable long-acting release octreotide (OCT-LAR) (30 mg/28 days). Design, Subjects and Methods: 34 patients (17 male, 25-85 years, 33 macroadenomas) were enrolled in this prospective study. OCT-LAR was administered as primary (n = 4) and as secondary (n = 30) treatment: after surgery (n = 16), after surgery + radiotherapy (RT) (n = 11), and after RT only (n = 3). Duration of OCT-LAR therapy prior to CAB was 24 8 12 months. The immunohistochemical features of the tumors disclosed GH/PRL co-secretion in 11/21 patients. 13 patients had high PRL levels prior to CAB. The initial CAB dose was 1.5 mg/week. No IGF-I normalization led to a dose increase to 3.5 mg/week. The OCT-LAR dose was kept stable during treatment. IGF-I, GH and PRL levels were compared before and after CAB association. OCT-LAR was withdrawn in patients who achieved IGF-I normalization, in order to assess the influence of CAB. Results: Comparing OCT-LAR to OCT-LAR/CAB treatment, there was a significant decrease in mean GH, IGF-I, %ULNR- IGF-I and PRL levels. During OCT-LAR/CAB treatment, IGF-I normalized in 19 patients (56%). IGF-I normalization was correlated to lowest IGF-I levels on OCT-LAR monotherapy, but not to baseline PRL levels or GH/PRL co-expression. OCT-LAR withdrawn in all who had achieved IGF-I normalization on combined therapy resulted in IGF-I elevation to abnormal levels in all patients. Gastro intestinal symptoms were reported by 12 patients. Conclusion: OCT-LAR and CAB association has been shown to be an effective alternative therapy for those acromegalics who still have active acromegaly despite monotherapy with SA, mainly for those with lower pretreatment IGF-I concentrations. According to previous studies, the beneficial effects of CAB occur even when pretreatment PRL is normal and/or there is no tumor GH/PRL co-expression. Copyright (C) 2009 S. Karger AG, Basel

Current management practices for acromegaly: an international survey

To determine whether peer-reviewed consensus statements have changed clinical practice, we surveyed acromegaly care in specialist centers across the globe, and determined the degree of adherence to published consensus guidelines on acromegaly management. Sixty-five acromegaly experts who participated in the 7th Acromegaly Consensus Workshop in March 2009 responded. Results indicated that the most common referring sources for acromegaly patients were other endocrinologists (in 26% of centers), neurosurgeons (25%) and primary care physicians (21%). In sixty-nine percent of patients, biochemical diagnoses were made by evaluating results of a combination of growth hormone (GH) nadir/basal GH and elevated insulin like growth factor-I (IGF-I) levels. In both Europe and the USA, neurosurgery was the treatment of choice for GH-secreting microadenomas and for macroadenomas with compromised visual function. The most widely used criteria for neurosurgical outcome assessment were combined measurements of IGF-I and GH levels after oral glucose tolerance test (OGTT) 3 months after surgery. Ninety-eight percent of respondents stated that primary treatment with somatostatin receptor ligands (SRLs) was indicated at least sometime during the management of acromegaly patients. In nearly all centers (96%), the use of pegvisomant monotherapy was restricted to patients who had failed to achieve biochemical control with SRL therapy. The observation that most centers followed consensus statement recommendations encourages the future utility of these workshops aimed to create uniform management standards for acromegaly.

Lipoxin A(4) attenuates zymosan-induced arthritis by modulating endothelin-1 and its effects

BACKGROUND AND PURPOSE Lipoxin A(4) (LXA(4)) is a lipid mediator involved in the resolution of inflammation. Increased levels of LXA(4) in synovial fluid and enhanced expression of the formyl peptide receptor 2/lipoxin A(4) receptor (FPR2/ALX) in the synovial tissues of rheumatoid arthritis patients have been reported. Endothelins (ETs) play a pivotal pro-inflammatory role in acute articular inflammatory responses. Here, we evaluated the anti-inflammatory role of LXA(4), during the acute phase of zymosan-induced arthritis, focusing on the modulation of ET-1 expression and its effects. EXPERIMENTAL APPROACH The anti-inflammatory effects of LXA(4), BML-111 (agonist of FPR2/ALX receptors) and acetylsalicylic acid (ASA) pre- and post-treatments were investigated in a murine model of zymosan-induced arthritis. Articular inflammation was assessed by examining knee joint oedema; neutrophil accumulation in synovial cavities; and levels of prepro-ET-1 mRNA, leukotriene (LT)B(4), tumour necrosis factor (TNF)-alpha and the chemokine KC/CXCL1, after stimulation. The direct effect of LXA(4) on ET-1-induced neutrophil activation and chemotaxis was evaluated by shape change and Boyden chamber assays respectively. KEY RESULTS LXA(4), BML-111 and ASA administered as pre- or post-treatment inhibited oedema and neutrophil influx induced by zymosan stimulation. Zymosan-induced preproET-1 mRNA, KC/CXCL1, LTB(4) and TNF-alpha levels were also decreased after LXA(4) pretreatment. In vitro, ET-1-induced neutrophil chemotaxis was inhibited by LXA4 pretreatment. LXA(4) treatment also inhibited ET-1-induced oedema formation and neutrophil influx into mouse knee joints. CONCLUSION AND IMPLICATION LXA(4) exerted anti-inflammatory effects on articular inflammation through a mechanism that involved the inhibition of ET-1 expression and its effects.

Periorbital changes associated with topical bimatoprost

Purpose: To describe periorbital changes induced by chronic topical therapy with daily bimatoprost 0.03% (Lumigan, Allergan Inc., Irvine, CA, U.S.A.). Methods: A clinical investigation of 5 nonconsecutive patients with unilateral glaucoma treated daily with topical bimatoprost 0.03% for up to 4 years prior to presentation. Results: In eyes treated with bimatoprost 0.03% the authors noted periorbital fat atrophy, deepening of the upper eyelid sulcus, relative enophthalmos, loss of the lower eyelid fullness, and involution of dermatochalasis compared with the fellow untreated eye. By inspecting old photographs the authors confirmed that these unilateral changes were not present prior to starting bimatoprost. In addition, these changes were partially reversible after discontinuation of the medication, whenever that was possible. In 2 cases imaging studies confirmed the clinical impression that these findings were not related to primary orbital pathology. Conclusions: Physicians and patients should be aware of the potential of bimatoprost 0.03% to produce periorbital changes.

Transdermal Pharmacology of Small Molecule Cyclic C5a Antagonists

Overproduction or underregulation of the proinflammatory complement component C5a has been implicated in numerous immune and inflammatory conditions. Therefore, targeting the C5a receptor (C5aR) has become an innovative strategy for antiinflammatory drug development. The novel cyclic peptide C5aR antagonist, AcF-[OP(D-Cha)WR] (PMX53), attenuates injury in numerous animal models of inflammation following intravenous, subcutaneous, intraperitoneal, and oral administration. In the present study the transdermal pharmacology of PMX53 and three analogs designed with increased lipophilicity, hydrocinnamate-[OP(D-Cha)WCit] (PMX200), AcF-[OP(D-Cha)WCit] (PMX201) and hydrocinnamate-[OP(D-Cha)WR] (PMX205), have been examined in order to assess their transdermal permeability and inhibitory effect on C5a-mediated lipopolysaccharide (LPS)-induced systemic responses. In the rat, PMX53, PMX201, and PMX205, were bioavailable following topical dermal administration (10 mg/50 cm(2) site/rat). All analogs functionally antagonized neutropenia and hypotension induced by systemic challenge with LPS (I mg/kg i.v.). Interestingly, PMX200 attenuated LPS-induced neutropenia more effectively than other analogs, despite undetectable (< 5 ng/ml) circulating levels following topical administration. In conclusion, we have demonstrated that cyclic peptide C5aR antagonists can penetrate transdermally sufficiently to have systemic effects. However, increasing lipophilicity in these compounds did not result in increased blood levels. Nonetheless, topical application of C5aR antagonists produced circulating levels of the drugs that antagonized the LPS-induced systemic responses of neutropenia and hypotension. This suggests that these small-molecule C5aR antagonists may be developed for topical administration for the treatment of local and systemic inflammatory conditions in the human and veterinary pharmaceutical markets.

Solid-state NMR structure determination of melittin in a lipid environment

Solid-state C-13 NMR spectroscopy was used to investigate the three-dimensional structure of melittin as lyophilized powder and in ditetradecylphosphatidylcholine (DTPC) membranes. The distance between specifically labeled carbons in analogs [1-C-13]Gly3-[2-C-13]Ala4, [1-C-13]Gly3-[2-C-13]Leu6, [1-C-13]Leu13-[2-C-13]Ala15, [2-C-13]Leu13-[1-C-13]Ala15, and [1-C-13]Leu13-[2-C-13]Leu16 was measured by rotational resonance. As expected, the internuclear distances measured in [1-C-13]Gly3-[2-C-13]Ala4 and [1-C-13]Gly3-[2-C-13]Leu6 were consistent with alpha -helical structure in the N-terminus irrespective of environment. The Internuclear distances measured in [1-C-13]Leu13-[2-C-13]Ala15, [2-C-13]Leu13-[1-C-13]Ala15, and [1-C-13]Leu13-[2-C-13]Leu16 revealed, via molecular modeling, some dependence upon environment for conformation in the region of the bend in helical structure induced by Pro14. A slightly larger interhelical angle between the N- and C-terminal helices was indicated for peptide in dry or hydrated gel state DTPC (139 degrees -145 degrees) than in lyophilized powder (121 degrees -139 degrees) or crystals (129 degrees). The angle, however, is not as great as deduced for melittin in aligned bilayers of DTPC in the liquid-crystalline state (similar to 160 degrees) (R. Smith, F. Separovic, T. J. Milne, A. Whittaker, F. M. Bennett, B. A. Cornell, and A. Makriyannis, 1994, J. Mol, Biol 241:456-466). The study illustrates the utility of rotational resonance in determining local structure within peptide-lipid complexes.

Enzymology, structure, and dynamics of acetohydroxy acid isomeroreductase

Acetohydroxy acid isomeroreductase is a key enzyme involved in the biosynthetic pathway of the amino acids isoleucine, valine, and leucine. This enzyme is of great interest in agrochemical research because it is present only in plants and microorganisms, making it a potential target for specific herbicides and fungicides. Moreover, it catalyzes an unusual two-step reaction that is of great fundamental interest. With a view to characterizing both the mechanism of inhibition by potential herbicides and the complex reaction mechanism, various techniques of enzymology, molecular biology, mass spectrometry, X-ray crystallography, and theoretical simulation have been used. The results and conclusions of these studies are described briefly in this paper.

Unprecedented oxidation of a biologically active aroylhydrazone chelator catalysed by iron(III): serendipitous identification of diacylhydrazine ligands with high iron chelation efficacy

Ligands of the 2-pyridylcarbaldehyde isonicotinoylhydrazone class show high iron (Fe) sequestering efficacy and have potential as agents for the treatment of Fe overload disease. We have investigated the mechanisms responsible for their high activity. X-ray crystallography studies show that the tridentate chelate 2-pyridylcarbaldehyde isonicotinoylhydrazone undergoes an unexpected oxidation to isonicotinoyl(picolinoyl)hydrazine when complexed with Fe-III. In contrast, in the absence of Fel the parent hydrazone is not oxidized in aerobic aqueous solution. To examine whether the diacylhydrazine could be responsible for the biological effects of 2-pyridylcarbaldehyde isonicotinoylhydrazone, their Fe chelation efficacy was compared. In contrast to its parent hydrazone, the diacylhydrazine showed little Fe chelation activity. Potentiometric titrations suggested that this might be because the diacylhydrazine was charged at physiological pH, hindering its access across membranes to intracellular Fe pools. In contrast, the Fe complex of this diacylhydrazine was charge neutral, which may allow facile movement through membranes. These data allow a model of Fe chelation for this compound to be proposed: the parent aroylhydrazone diffuses through cell membranes to bind Fe and is subsequently oxidized to the diacylhydrazine complex which then diffuses from the cell. Other diacylhydrazine analogues that were charge neutral at physiological pH demonstrated high Fe chelation efficacy. Thus, for this class of ligands, the charge of the chelator appears to be an important factor for determining their ability to access intracellular Fe. The results of this study are significant for understanding the biological activity of 2-pyridylcarbaldehyde isonicotinoylhydrazone and for the design of novel diacylhydrazine chelators for clinical use.

Species dependence for binding of small molecule agonist and antagonists to the C5a receptor on polymorphonuclear leukocytes

This study investigated the receptor binding affinities of a C5a agonist and cyclic antagonists for polymorphonuclear leukocytes (PMNs) isolated from human, sheep, pig, dog, rabbit, guinea pig, rat and mouse. The affinities of the two small molecule antagonists, F-[OPdChaWR] and AcF-[OPdChaWR], and the agonist, YSFKPMPLaR, revealed large differences in C5a receptor (C5aR) affinities between species. The antagonists bound to human, rat and dog PMNs with similar high affinities, but with lower affinities to PMNs from all other species. The C5a agonist also bound with varying affinities between species, but showed a different affinity profile to the antagonists. In contrast, recombinant human C5a had similar affinity for PMNs of all species investigated. The low correlation between the affinities of the antagonists and the agonist between species either suggests that different receptor residues are important for distinguishing between agonist/antagonist binding, or that the agonist and antagonist peptides bind to two distinct sites within the C5aR.

The AF-1 Domain of the Orphan Nuclear Receptor NOR-1 Mediates Trans-activation, Coactivator Recruitment, and Activation by the Purine Anti-metabolite 6-Mercaptopurine

NOR-1/NR4A3 is an orphan member of the nuclear hormone receptor superfamily. NOR-1 and its close relatives Nurr1 and Nur77 are members of the NR4A subgroup of nuclear receptors. Members of the NR4A subgroup are induced through multiple signal transduction pathways. They have been implicated in cell proliferation, differentiation, T-cell apoptosis, chondrosarcomas, neurological disorders, inflammation, and atherogenesis. However, the mechanism of transcriptional activation, coactivator recruitment, and agonist-mediated activation remain obscure. Hence, we examined the molecular basis of NOR-1-mediated activation. We observed that NOR-1 trans-activates gene expression in a cell- and target-specific manner; moreover, it operates in an activation function (AF)-1-dependent manner. The N-terminal AF-1 domain delimited to between amino acids 1 and 112, preferentially recruits the steroid receptor coactivator (SRC). Furthermore, SRC-2 modulates the activity of the AF-1 domain but not the C-terminal ligand binding domain (LBD). Homology modeling indicated that the NOR-1 LBD was substantially different from that of hRORbeta, a closely related AF-2-dependent receptor. In particular, the hydrophobic cleft characteristic of nuclear receptors was replaced with a very hydrophilic surface with a distinct topology. This observation may account for the inability of this nuclear receptor LBD to efficiently mediate cofactor recruitment and transcriptional activation. In contrast, the N-terminal AF-1 is necessary for cofactor recruitment and can independently conscript coactivators. Finally, we demonstrate that the purine anti-metabolite 6-mercaptopurine, a widely used antineoplastic and anti-inflammatory drug, activates NOR-1 in an AF-1-dependent manner. Additional 6-mercaptopurine analogs all efficiently activated NOR-1, suggesting that the signaling pathways that modulate proliferation via inhibition of de novo purine and/or nucleic acid biosynthesis are involved in the regulation NR4A activity. We hypothesize that the NR4A subgroup mediates the genotoxic stress response and suggest that this subgroup may function as sensors that respond to genotoxicity.

Bridgehead arylation: A direct route to advanced intermediates for the synthesis of C-20 diterpene alkaloids

[GRAPHICS] Rapid access to the ABCE ring system of the C-20 diterpene alkaloids was achieved by silver(I)-promoted intramolecular Friedel-Crafts arylation of a functional group-specific 5-bromo-3-azabicyclo[3.3.1]nonane derivative.

Synthesis of novel 2-amino-1,3-thiazole-5-carboxylates utilising ultrasonic and thermally mediated aminolysis

Novel 2-amino-1,3-thiazole-5-carboxylates have been synthesised in high yield by unprecedented ultrasonic and thermally mediated nucleophilic displacement of bromide from ethyl 2-bromo-1,3-thiazole-5-carboxylate by primary, secondary and aryl amines.