Structure-activity relationships of piperazinebenzylamines as potent and selective agonists of the human melanocortin-4 receptor

SAR studies on a series of piperazinebenzenes directed toward the human melanocortin-4 receptor resulted in potent MC4R agonists. Replacement of the triazole moiety of an initial lead 4 by a basic nitrogen baring a lipophilic side-chain increased the binding affinities of these compounds. Analogs bearing an additional hetero-atom in the side-chain possessed good agonist potency. Thus, 11h had a Ki of 11 nM, and 13g exhibited an EC50 of 3.8 nM and a Ki of 6.4 nM.     

Influence of the extraction mode on the yield of some furanocoumarins from Pastinaca sativa fruits

Analysis of plant material is an important task in chemotaxonomical investigations, in search of plants with pharmacological activity or in standardisation of plant drugs. The choice of optimal conditions for the analysis of plant material and effect of extraction method on the yield of furanocoumarins from Pastinaca sativa fruits were examined. The following extraction methods were used in experiments: exhaustive extraction in Soxhlet apparatus, ultrasonification (USAE) at 25 and 60 degrees C, microwave-assisted solvent extraction in open and closed system (MASE) and accelerated solvent extraction (ASE). In most cases, the yield of furanocoumarins was highest by use of ASE method as well as by ultrasonification at 60 degrees C.     

The energetics of specific binding of AT-hooks from HMGA1 to target DNA

The interaction of the second and third AT-hooks of HMGA1 (formerly HMGI/Y), which bind selectively in the minor groove of an AT-rich DNA sequence, was studied at different temperatures and ionic strengths by spectropolarimetry, spectrofluorimetry, isothermal titration calorimetry and differential scanning calorimetry. The data show that binding of the ten amino acid core element of the two AT-hooks, which penetrates deep into the minor groove, is entropically driven: both the entropy and enthalpy of association of the peptides to the target DNA are positive up to 50 degrees C. The seven amino acid extension of the core in the second AT-hook, which extends out from the minor groove and loops over the phosphodiester backbone, adds a substantial negative enthalpic component into the binding of the 17 residue DBD2 peptide to DNA that corresponds in magnitude to the enthalpy of formation of two hydrogen bonds. The ionic strength dependence of the association constant allowed an estimation of the electrostatic component of binding and, by subtraction, the contribution of the non-electrostatic component, which results from dehydration of the contacting surfaces and makes up almost 70% of the total energy of complex formation. The exceptionally large positive entropy and enthalpy of association of the core AT-hook peptides with target DNA suggest that the water, which is removed from the minor groove of DNA upon binding, is in a highly ordered state. Acetylation of the lysine residue in the second AT-hook, which corresponds to Lys65 of HMGA1, has little effect on the DNA binding; so it appears that repression of the hIFNbeta gene, which follows this modification, is not a direct result of the abrogation of DNA binding.     

Rapid detection of the hypertension-associated A1166C polymorphism of the angiotensin II type 1 receptor (AGTR1)

Screening for polymorphisms in the human type 1 angiotensin II receptor locus (AGTR1) has led to the identification of an A1166C transversion in the 3'-untranslated region. This molecular variant, C(1166), has been linked to essential hypertension. We describe here a rapid method for the detection of this point mutation by a simple modification of PCR amplification with allele-specific oligonucleotides (ASO), so as to avoid a hybridization procedure involving either radioactive- or non-radioactive-labeled probes, labeled primers, or restriction typing. The procedure described is convenient for routine clinical laboratory use with manual sample processing and offers the potential for further automation, as well.     

BOB.1/OBF.1 deficiency affects marginal-zone B-cell compartment

Marginal-zone (MZ) B cells represent a first line of defense against particulate blood-borne antigens. Together with the B1 cells, they are responsible for the early response against type II T-independent antigens. The molecular pathways controlling the development of MZ B cells are only poorly understood. We found that these cells are virtually absent in mice deficient in the BOB.1/OBF.1 coactivator. Loss of these B cells was demonstrated by the lack of cells showing the appropriate cell surface phenotype but also by histological analyses and tri-nitro-phenol-Ficoll capturing. The lack of these cells is a B-cell-intrinsic defect, as shown by bone marrow complementation experiments. We also show that the expression of BOB.1/OBF.1 in peripheral B cells is required for the development of MZ B lymphocytes. Our analysis of BOB.1/OBF.1-deficient splenic B cells reveals alterations in cell motility, tumor necrosis factor receptor expression, and B-cell receptor (BCR) signaling. These changes could contribute to the loss of MZ B lymphocytes by altering the maturation of the cells. Interestingly, development of and BCR signaling in B1 B cells are completely normal in BOB.1/OBF.1 mutant mice.     

Plasma N-glycome composition associates with chronic low back pain

Background

Low back pain (LBP) is the symptom of a group of syndromes with heterogeneous underlying mechanisms and molecular pathologies, making treatment selection and patient prognosis very challenging. Moreover, symptoms and prognosis of LBP are influenced by age, gender, occupation, habits, and psychological factors. LBP may be characterized by an underlying inflammatory process. Previous studies indicated a connection between inflammatory response and total plasma N-glycosylation. We wanted to identify potential changes in total plasma N-glycosylation pattern connected with chronic low back pain (CLBP), which could give an insight into the pathogenic mechanisms of the disease.

Coupled electron and proton transfer reactions during the O→E transition in bovine cytochrome c oxidase

A combined DFT/electrostatic approach is employed to study the coupling of proton and electron transfer reactions in cytochrome c oxidase (CcO) and its proton pumping mechanism. The coupling of the chemical proton to the internal electron transfer within the binuclear center is examined for the O→E transition. The novel features of the His291 pumping model are proposed, which involve timely well-synchronized sequence of the proton-coupled electron transfer reactions. The obtained pK(a)s and E(m)s of the key ionizable and redox-active groups at the different stages of the O→E transition are consistent with available experimental data. The PT step from E242 to H291 is examined in detail for various redox states of the hemes and various conformations of E242 side-chain. Redox potential calculations of the successive steps in the reaction cycle during the O→E transition are able to explain a cascade of equilibria between the different intermediate states and electron redistribution between the metal centers during the course of the catalytic activity. All four electrometric phases are discussed in the light of the obtained results, providing a robust support for the His291 model of proton pumping in CcO.     

The patients with clinically isolated syndrome and relapsing remitting multiple sclerosis show different levels of advanced protein oxidation products and total thiol content in plasma and CSF

Advanced oxidation protein products (AOPP) and total thiol (SH) groups levels in plasma and CSF were studied in a cohort of 50 clinically isolated syndrome (CIS) and 57 relapsing remittent multiple sclerosis (RRMS) patients related to 20 control group (CG) patients’ values. The obtained results were compared regarding patients demographic, biochemical, clinical (EDSS) and MRI features (total T2 weighted lesions number and Gd enhancement lesion volume).     

Changes in cardiac Na<Superscript>+</Superscript>/K<Superscript>+</Superscript>-ATPase expression and activity in female rats fed a high-fat diet

The aim of this study was to investigate whether the presence of endogenous estradiol alters the effects of a high-fat (HF) diet on activity/expression of the cardiac Na⁺/K⁺-ATPase, via PI3K/IRS and RhoA/ROCK signalling cascades in female rats. For this study, female Wistar rats (8 weeks old, 150–200 g) were fed a standard diet or a HF diet (balanced diet for laboratory rats enriched with 42% fat) for 10 weeks. The results show that rats fed a HF diet exhibited a decrease in phosphorylation of the α₁ subunit of Na⁺/K⁺-ATPase by 30% (p < 0.05), expression of total α₁ subunit of Na⁺/K⁺-ATPase by 31% (p < 0.05), and association of IRS1 with p85 subunit of PI3K by 42% (p < 0.05), while the levels of cardiac RhoA and ROCK2 were significantly increased by 84% (p < 0.01) and 62% (p < 0.05), respectively. Our results suggest that a HF diet alters cardiac Na⁺/K⁺-ATPase expression via molecular mechanisms involving RhoA/ROCK and IRS-1/PI3K signalling in female rats.