Intrarenal growth of the walker 256 tumour and renal vein concentrations of PGE2, PGF2α, and TXB2: Effects of diazepam

Walker 256 tumours grafted under the left kidney capsules in rats showed enhanced growth following daily treatment with diazepam 500 μg (1.7 mg/kg body weight) subcutaneously but not with 1250 μg. Thromboxane B₂ (the metabolite of TXA₂) levels in venous drainage from both the tumour bearing left kidney and ²from the right control kidney were reduced significantly in all the three groups of tumour bearing rats. Plasma PGE₂ was higher in the venous drainage from the tumour bearing left kidney than from the right control kidney. Significantly higher levels were measured following 500 μg but not after 1250 μg of diazepam. Plasma PGF_2α on the other hand, was lower in the plasma from the tumour bearing kidney and was further lowered in animals receiving diazepam treatment.     

Part 2: Design, synthesis and evaluation of hydroxyproline-derived α2δ ligands

Conformational constraint has been used to design a potent series of α₂δ ligands derived from the readily available starting material (2S,4R)-hydroxy-l-proline. The ligands have improved physicochemistry and potency compared to their linear counterparts (described in our earlier publication) and the lead compound has been progressed to clinical development.     

Synthesis of sucrose epoxides,partial de-esterification of 1′,2:4,6-di-O-isopropylidenesucrose tetra-acetate,and selective tosylation of 3,6′-di-O-acetyl-1′,2:4,6-di-O-isopropylidenesucrose

Selective de-esterification of 1′,2:4,6-di-O-isopropylidenesucrose tetra-acetate² (1) with methanolic ammonia at ?10° gave an inseparable mixture (2+3) of the 3,4′,6′- and 3,3′,6′-triacetates and also the 4,6′-diacetate 4. When the reaction was performed at 5°, it gave 4, the 4-acetate 8, and the parent diacetal 9. These derivatives allow selective reaction at hydroxyl groups in sucrose, in particular at HO-3′ and, HO-4′, not hitherto possible. Mesylation of 4 gave the 3′,4′-dimesylate 7, which, on treatment with aqueous acetic acid followed by acetylation, afforded 3′,4′-di-O-mesylsucrose hexa-acetate (11). Treatment of 11 with sodium methoxide in methanol at 70° for 1 min gave the ribo-3′,4′-epoxide 12 as the minor, and the lyxo-3′,4′-epoxide 13 as the major, product. Selective tosylation of 4 gave the 3',4'-ditosylate 14 (3.7%), 4′-tosylate 15 (3.1%), and 3'-tosylate 16 (31%), indicating the order of reactivity HO-3′>HO-4′ in 4. De acetalation of 15 and 16 followed by acetylation gave the hepta-acetates of 4′- and 3′-O-tosylsucrose, respectively, which were converted into the respective epoxides, 13 and 12, by methanolic sodium methoxide.     

Benzimidazole 2′-Isonucleosides: Design,Synthesis, and Antiviral Activity of 2-Substituted-5,6-Dichlorobenzimidazole 2′-Isonucleosides

Abstract

2,5,6-Trihalogenated benzimidazole-β-D-ribofuranosyl nucleosides and 2-substituted amino-5,6-dichlorobenzimidazole-β-L-ribofuranosyl nucleosides are potent and selective inhibitors of human cytomegalovirus (HCMV). The D-ribofuranosyl analogs are metabolized rapidly in vivo rendering them unsuitable as drug candidates. The primary source of instability is thought to be the anomeric bond. The synthesis of a series of chemically stable benzimidazole-2′-isonucleosides is presented. The synthetic schemes employed are based on nucleophilic displacements of a 2′-tosylate from carbohydrate intermediates with 2-bromo-5,6-dichlorobenzidazole. 2-Bromo and 2-isopropyl amino analogs with 3′- and 5′-oxo and deoxy substitutions were prepared. The benzimidazole-2′-isonucleosides presented here demonstrated reduced activity against HCMV when compared to other D-ribofuranosyl benzimidazole analogs. In addition, they were not found to be inhibitors of HIV.     

Discovery of α-amidosulfones as potent and selective agonists of CB2: Synthesis,SAR, and pharmacokinetic properties

A series of α-amidosulfones were found to be potent and selective agonists of CB₂. The discovery, synthesis, and structure–activity relationships of this series of agonists are reported. In addition, the pharmacokinetic properties of the most promising compounds are profiled.     

Hormone studies inMyxine glutinosa: effects of the eicosanoids arachidonic acid,prostaglandin E1, E2, A2, F2α, thromboxane B2 and of indomethacin on plasma cortisol,blood pressure,urine flow and electrolyte balance

Summary Hagfish,Myxine glutinosa, were used in an investigation of the possible effects of various eicosanoids and the prostaglandin synthetase inhibitor indomethacin, on cortisol production, blood pressure control, urine flow and electrolyte balance.Cortisol levels in plasma of untreated control animals and plasma from animals 1 h following injection of 50 g kg^–1 prostaglandin E₁, E₂, A₂, F₂ TXB₂ and indomethacin were not detectable. However, plasma cortisol levels rose to between 10 and 26 pg ml^–1 1 h following injection of either 50 g kg^–1 arachidonic acid or prostaglandin E₂. This rise was similar in magnitude to that produced 1 h following administration of 50 g kg^–1 porcine ACTH.The resting dorsal aortic blood pressure of between 3.50 and 3.75 mmHg was reduced on average by 50% for 12–15 min when animals received 10 g kg^–1 arachidonic acid, prostaglandin E₁, E₂, A₂, and TXB₂ and was effectively reduced to zero for 20 min or more following 50 g kg^–1 of these eicosanoids. Similar doses of prostaglandin F₂, however, evoked an increase in blood pressure (19–33%) whilst indomethacin was without effect.Control measurements of urine flow inMyxine were estimated to be between 540 and 660 l h^–1 kg^–1. There was a marked reduction in urine output following the arterial vasodepression induced by arachidonic acid, prostaglandin E₁, E₂, A₂ and TXB₂ in doses of 10 g kg^–1, an effect which became even more pronouced following injection of 50 g kg^–1 quantities, leading in some cases to complete anuria. There was no significant change in urine volume following either the vasopressor action of prostaglandin F₂ or following indomethacin.None of the compounds tested in this study significantly influenced the plasma or urine electrolyte status ofMyxine.     

Inhibition of Neutrophil Superoxide Secretion By of Preservative, Methylhydroxybenzoate: Effects Mediated By Perturbation of Intracellular Ca2+?

The preservative, methylhydroxybenzoate inhibited O₂^- secretion from human neutrophils activated by both the chemotactic peptide fMet-Leu-Phe and phorbol myristate acetate (PMA): the low level of oxidant secretion activated by the ionophore A23187 was similarly reduced in preservative-treated suspensions. Oxidant secretion was similarly reduced in fMet-Leu-Phe and A23187 treated suspensions in which intracellular Ca²⁺ was buffered by loading with Quin-2, indicating that methylhydroxybenzoate may exert its effects by perturbation of intracellular Ca²⁺ -dependent processes. Methylhydroxybenzoate could mimic EGTA in preventing the Ca²⁺ dependent enhancement of trypsin activity and could also bind this cation in experiments using a Ca²⁺ electrode, although the preservative bound Ca²⁺ more slowly and had a lower affinity than EGTA. These data indicate that methylhydroxybenzoate may exert its effects on neutrophils by perturbation of Ca²⁺-dependent activation pathways and this phenomenon may also explain its other known pharmacological effects. Furthermore, these observations provide an insight into the mechanisms by which intracellular Ca²⁺ may regulate oxidant secretion.     

Oligomeric States along the Folding Pathways of β2-Microglobulin: Kinetics,Thermodynamics, and Structure

The transition of proteins from their soluble functional state to amyloid fibrils and aggregates is associated with the onset of several human diseases. Protein aggregation often requires some structural reshaping and the subsequent formation of intermolecular contacts. Therefore, the study of the conformation of excited protein states and their ability to form oligomers is of primary importance for understanding the molecular basis of amyloid fibril formation. Here, we investigated the oligomerization processes that occur along the folding of the amyloidogenic human protein β2-microglobulin. The combination of real-time two-dimensional NMR data with real-time small-angle X-ray scattering measurements allowed us to derive thermodynamic and kinetic information on protein oligomerization of different conformational states populated along the folding pathways. In particular, we could demonstrate that a long-lived folding intermediate (I-state) has a higher propensity to oligomerize compared to the native state. Our data agree well with a simple five-state kinetic model that involves only monomeric and dimeric species. The dimers have an elongated shape with the dimerization interface located at the apical side of β2-microglobulin close to Pro32, the residue that has a trans conformation in the I-state and a cis conformation in the native (N) state. Our experimental data suggest that partial unfolding in the apical half of the protein close to Pro32 leads to an excited state conformation with enhanced propensity for oligomerization. This excited state becomes more populated in the transient I-state due to the destabilization of the native conformation by the trans-Pro32 configuration.     

Transbuccal delivery of 5-Aza-2′-deoxycytidine: Effects of drug concentration,buffer solution,and bile salts on permeation

Delivery of 5-aza-2′-deoxycytidine (decitabine) across porcine buccal mucosa was evaluated as an alternative to the complex intravenous infusion regimen currently used to administer the drug. A reproducible high-performance liquid chromatography method was developed and optimized for the quantitative determination of this drug. Decitabine showed a concentration-dependent passive diffusion process across porcine buccal mucosa. An increase in the ionic strength of the phosphate buffer from 100 to 400 mM decreased the flux from 3.57±0.65 to 1.89±0.61 μg/h/cm². Trihydroxy bile salts significantly enhanced the flux of decitabine at a 100 mM concentration (P>.05). The steady-state flux of decitabine in the presence of 100 mM of sodium taurocholate and sodium glycocholate was 52.65±9.48 and 85.22±7.61 μg/cm²/h, respectively. Two dihydroxy bile salts, sodium deoxytaurocholate and sodium deoxyglycocholate, showed better enhancement effect than did trihydroxy bile salts. A 38-fold enhancement in flux was achieved with 10 mM of sodium deoxyglycocholate. Published: July 13, 2007     

Thyroidal enhancement of rat myocardial Na,K-ATPase: Preferential expression of α2 activity and mRNA abundance

Summary In hypothyroid rat myocardium, the low-ouabain-sensitivity Na,K-ATPase activity had aK _i =10^–4 m and accounted for 95% of the enzyme activity, while the high-ouabain-sensitivity activity contributed 5% to the total activity, with aK _i =3×10⁷ m. mRNA₁ was 7.2- and 5.5-fold more abundant than mRNA₂ and mRNA, respectively, in hypothyroid ventricles while mRNA₃ was undetectable. Administration of T₃ increased total Na,K-ATPase activity 1.6-fold; the low-ouabain-sensitivity activity increased 1.5-fold while high-ouabain-sensitivity activity was stimulated 3.2-fold. T₃ increased the number of high-affinity ouabain-binding sites 2.9-fold with no change inK _d (2×10^–7 m). The abundances of mRNA₁, mRNA₂, and mRNA (per unit RNA) following T₃ treatment increased 3.6-, 10.6-, and 12.7-fold, respectively. The larger increments in subunit mRNA abundances than in Na,K-ATPase activity suggests the involvement of translational and/or post-translational regulatory steps in Na,K-ATPase biogenesis in response to T₃. It is concluded that T₃ enhances myocardial Na,K-ATPase subunit mRNA abundances and Na,K-ATPase activity, and that the expression of the high- and low-ouabain-sensitivity activities are probably a reflection of the abundances of the 2 and 1 isoforms, respectively. The physiological role played by the subunit remains uncertain.     

Antitubercular activity of α,ω-diaminoalkanes,H2N(CH2)nNH2

A series of 11 α,ω-diaminoalkanes, (H₂N(CH₂)_nNH₂, n = 2–12) have been evaluated for their in vitro antibacterial activity against Mycobacterium tuberculosis H37Rv. Compounds, (H₂N(CH₂)_nNH₂, n = 9–12), exhibited a very good activities in the range 2.50–3.12 μg/mL, which can be compared with that of the first line drug, ethambutol (3.12 μg/mL). These results and a preliminary QSAR study can be considered an important start point for the rational design of new leads for anti-TB compounds.     

Metabolism of prostaglandin D2 in isolated rat lung: the stereospecific formation of 9α, 11β-prostaglandin F2 from prostaglandin D2

The metabolic transformation of exogenous prostaglandin D₂ was investigated in isolated perfused rat lung. Dose-dependent formation (2–150 ng) of 9α,11β-prostaglandin F₂, corresponding to about 0.1% of the perfused dose of prostaglandinD₂, was observed by specific radioimmunoassay both in the perfusate and in lung tissue after a 5-min perfusion. To investigate the reason for this low conversion ratio, we analyzed the metabolites of tritium-labeled 9α,11β-prostaglandin F₂ and prostaglandin D₂ by boric acid-impregnated TLC and HPLC. By 5 min after the start of perfusion, 9α,11β-prostaglandin F₂ disappeared completely from the perfusate and the major product formed remained unchanged during the remainder of the 30-min perfusion. The major product was separated by TLC and identified as 13,14-dihydro-15-keto-9α,11β-prostaglandin F₂ by GC/MS. In contrast, pulmonary breakdown of prostaglandin D₂ was slow and two major metabolites in the perfusate increased with time, each representing 56% and 11% of the total radioactivity at the end of the perfusion. The major product (56%) was identified as 13,14-dihydro-15-ketoprostaglandin D₂ and the minor one (11%) was tentatively identified as 13,14-dihydro-15-keto-9α,11β-prostaglandin F₂ based on the results from radioimmunoassays, TLC, HPLC, and the time course of pulmonary breakdown. These results demonstrate that the metabolism of prostaglandin D₂ in rat lung involves at least two pathways, one by 15-hydroxyprostaglandin dehydrogenase and the other by 11-ketoreductase, and that the 9α,11β-prostaglandin F₂ formed is rapidly metabolized to 13,14-dihydro-15-keto-9α,11β-prostaglandin F₂.     

Role of miRNAs in the pathogenesis of T2DM,insulin secretion,insulin resistance,and β cell dysfunction: the story so far

Journal of Physiology and Biochemistry - Diabetes, the most common endocrine disorder, also known as a silent killer disease, is characterized by uncontrolled hyperglycemia. According to the...     

Revision of fossil Metretopodidae (Insecta: Ephemeroptera) in Baltic amber – Part 2: Description of a new species of Metretopus Eaton, 1901

In the second part of the revision of fossil Metretopodidae, a new species of the genus Metretopus Eaton, 1901 is described and illustrated based on a male imago. Metretopus dividussp. nov. is the second fossil species of the genus. Distinguishing characters for its separation from other fossil and recent representatives of Metretopus are discussed. http://www.zoobank.org/urn:lsid:zoobank.org:act:BCC5CB69-8014-4DA1-A0DA-DCF714969081