Contribution of transmembrane domain V amino acids to β1l-adrenoceptor activity and affinity

There are two binding sites on the β1-adrenoceptor (AR), β1H and β1L corresponding to high and low affinity binding sites respectively, which can be activated to cause cardiostimulation (reviewed Kaumann and Molenaar, 2008). Some β-blockers that block β1AR and β2ARs can activate β1LARs at higher concentrations than those required to cause blockade. The β2AR does not form a corresponding low affinity binding site (Baker et al 2002) and therefore we postulated that heterologous amino acids are responsible for the formation of β1LAR. Our aim was to investigate whether heterologous amino acids of transmembrane domain V (TMDV) of β1AR and β2ARs contribute to β1LAR. β1ARs, β2ARs and mutant β1ARs containing all (β1(β2TMDV)AR) or single amino acids of TMDV of the β2AR were prepared and stably expressed in Chinese Hamster Ovary cells. Concentration-effect curves for cyclicAMP accumulation were carried out for (-)-CGP12177 or (-)-isoprenaline in the absence or presence of (-)-bupranolol. _______________________________________________________________________ (-)-CGP 12177 (-)-Bupranolol affinity (pKB) pEC50 vs (-)-CGP 12177 vs (-)-isoprenaline _______________________________________________________________________ β1AR 8.00 ± 0.11 (11) 7.23 ± 0.23 (5) 9.52 ± 0.28 (5) β2AR (high density) 9.24 ± 0.14 (5) 9.82 ± 0.52 (8) xPaulxxxxxxx β2AR (low density) no effect β1(β2TMV)AR 8.86 ± 0.10 (15) 8.06 ± 0.17 (8) 9.08 ± 0.22 (6) β1(V230I)AR 9.07 ± 0.07 (10) 7.64 ± 0.12 (8) 9.36 ± 0.28 (9) β1(R222Q)AR 8.09 ± 0.29 (6) 7.33 ± 0.23 (5) 9.36 ± 0.08 (6) β1(V230A)AR 7.59 ± 0.09 (6) 7.32 ± 0.24 (4) 8.62 ± 0.18 (5) _______________________________________________________________________ The potency of (-)-CGP12177 was higher at β2AR than at β1AR consistent with activation through a low affinity site at the β1AR (β1LAR) but not β2AR. The presence of V230 in β1AR accounted for the lower potency of (-)-CGP 12177. The affinity of (-)-bupranolol at β1AR and mutants was higher when determined with (-)-isoprenaline than with (-)-CGP 12177. The affinity of (-)-bupranolol determined against (-)-CGP 12177 was lower at β1AR compared to β2AR. The presence of V230 in β1AR accounted in part for the lower affinity. In conclusion V230 of the β1AR contributes in part to the low affinity binding site of β1AR. Baker JG, Hall IP, Hill SJ (2002). Pharmacological characterization of CGP12177 at the human β2-adrenoceptor. Br J Pharmacol 137, 400−408 Kaumann AJ, Molenaar P (2008) The low-affinity site of the β1-adrenoceptor and its relevance to cardiovascular pharmacology. Pharmacol Ther 118, 303-336

Influence of parameters on the heterogeneous photocatalytic degradation of pesticides and phenolic contaminants in wastewater : a short review

In recent years, the application of heterogeneous photocatalytic water purification process has gained wide attention due to its effectiveness in degrading and mineralizing the recalcitrant organic compounds as well as the possibility of utilizing the solar UV and visible light spectrum. This paper aims to review and summarize the recently published works on the titanium dioxide (TiO2) photocatalytic oxidation of pesticides and phenolic compounds, predominant in storm and waste water effluents. The effect of various operating parameters on the photocatalytic degradation of pesticides and phenols are discussed. Results reported here suggested that the photocatalytic degradation of organic compounds depends on the type of photocatalyst and composition, light intensity, initial substrate concentration, amount of catalyst, pH of the reaction medium, ionic components in water, solvent types, oxidizing agents/electron acceptors, catalyst application mode, and calcinations temperature in water environment. A substantial amount of research has focused on the enhancement of TiO2 photocatalysis by modification with metal, non-metal and ion doping. Recent developments in TiO2 photocatalysis for the degradation of various pesticides and phenols are also highlighted in this review. It is evident from the literature survey that photocatalysis has shown good potential for the removal of various organic pollutants. However, still there is a need to find out the practical utility of this technique on commercial scale.

Proton-transfer compounds of isnipecotamide with the aromatic dicarboxylic acids 4-nitrophthalic, 4,5-dichlorophthalic, 5-nitroisophthalic and terephthalic acid

The structures of the 1:1 proton-transfer compounds of isonipecotamide (4-piperidinecarboxamide) with 4-nitrophthalic acid, 4-carbamoylpiperidinium 2-carboxy-4-nitrobenzoate, C6H13N2O8+ C8H4O6- (I), 4,5-dichlorophthalic acid, 4-carbamoylpiperidinium 2-carboxy-4,5-dichlorobenzoate, C6H13N2O8+ C8H3Cl2O4- (II) and 5-nitroisophthalic acid, 4-carbamoylpiperidinium 3-carboxy-5-nitrobenzoate, C6H13N2O8+ C8H4O6- (III) as well as the 2:1 compound with terephthalic acid, bis(4-carbamoylpiperidinium)benzene-1,2-dicarboxylate dihydrate, 2(C6H13N2O8+) C8H4O42- . 2H2O (IV)have been determined at 200 K. All salts form hydrogen-bonded structures, one-dimensional in (II) and three-dimensional in (I), (III) and (IV). In (I) and (III) the centrosymmetric R2/2(8) cyclic amide-amide association is found while in (IV) several different types of water-bridged cyclic associations are present [graph sets R2/4(8), R3/4(10), R4/4(12), R3/3(18) and R4/6(22)]. The one-dimensional structure of (I), features the common 'planar' hydrogen 4,5-dichlorophthalate anion together with enlarged cyclic R3/3(13) and R3/4(17) associations. With the structures of (I) and (III) the presence of head-to-tail hydrogen phthalate chain substructures is found. In (IV) head-to-tail primary cation-anion associations are extended longitudinally into chains through the water-bridged cation associations and laterally by piperidinium N-H...O(carboxyl) and water O-H...O(carboxyl) hydrogen bonds. The structures reported here further demonstrate the utility of the isonipecotamide cation as a synthon for the generation of stable hydrogen-bonded structures. An additional example of cation--anion association with this cation is also shown in the asymmetric three-centre piperidinium N-H...O,O'(carboxyl) interaction in the first-reported structure of a 2:1 isonipecotamide-carboxylate salt.

Hydrogen-bonding in the structures of the hydrated proton-transfer compounds of isonipecotamide with the isomeric indole-2 and indole-3-carboxylic acids

The structures of two hydrated proton-transfer compounds of 4-piperidinecarboxamide (isonipecotamide) with the isomeric heteroaromatic carboxylic acids indole-2-carboxylic acid and indole-3-carboxylic acid, namely 4-carbamoylpiperidinium indole-2-carboxylate dihydrate (1) and 4-carbamoylpiperidinium indole-3-carboxylate hemihydrate (2) have been determined at 200 K. Crystals of both 1 and 2 are monoclinic, space groups P21/c and P2/c respectively with Z = 4 in cells having dimensions a = 10.6811(4), b = 12.2017(4), c = 12.5456(5) Å, β = 96.000(4)o (1) and a = 15.5140(4), b = 10.2908(3), c = 9.7047(3) Å, β = 97.060(3)o (2). Hydrogen-bonding in 1 involves a primary cyclic interaction involving complementary cation amide N-H…O(carboxyl) anion and anion hetero N-H…O(amide) cation hydrogen bonds [graph set R22(9)]. Secondary associations involving also the water molecules of solvation give a two-dimensional network structure which includes weak water O-H…π interactions. In the three-dimensional hydrogen-bonded structure of 2, there are classic centrosymmetric cyclic head-to-head hydrogen-bonded amide-amide interactions [graph set R22(8)] as well as lateral cyclic amide-O linked amide-amide extensions [graph set R24(8)]. The anions and the water molecule, which lies on a twofold rotation axis, are involved in secondary extensions.

Hydrogen-bonding in cyclic imides and amide carboxylic acid derivatives from the facile reaction of cis-cyclohexane-1,2-carboxylic anhydride with o- and p-anisidine and m- and p-aminobenzoic acids

The structures of the open chain amide carboxylic acid rac-cis-[2-(2-methoxyphenyl)carbamoyl]cyclohexane-1-carboxylic acid, C15H19NO4, (I) and the cyclic imides rac-cis-2-(4-methoxyphenyl)-3a,4,5,6,7,7-hexahydroisoindole-1,3-dione,C15H17NO3, (II), chiral cis-2-(3-carboxyphenyl)-3a,4,5,6,7,7a-hexahydroisoindole-1,3-dione, C15H15NO4,(III) and rac-cis-2-(4-carboxyphenyl)- 3a,4,5,6,7,7a-hexahydroisoindole-1,3-dione monohydrate, C15H15NO4. H2O) (IV), are reported. In the amide acid (I), the phenylcarbamoyl group is essentially planar [maximum deviation from the least-squares plane = 0.060(1)Ang. for the amide O atom], the molecules form discrete centrosymmetric dimers through intermolecular cyclic carboxy-carboxy O-H...O hydrogen-bonding interactions [graph set notation R2/2(8)]. The cyclic imides (II)--(IV) are conformationally similar, with comparable phenyl ring rotations about the imide N-C(aromatic) bond [dihedral angles between the benzene and isoindole rings = 51.55(7)deg. in (II), 59.22(12)deg. in (III) and 51.99(14)deg. in (IV). Unlike (II) in which only weak intermolecular C-H...O(imide) hydrogen bonding is present, the crystal packing of imides (III) and (IV) shows strong intermolecular carboxylic acid O-H...O hydrogen-bonding associations. With (III), these involve imide O-atom acceptors, giving one-dimensional zigzag chains [graph set C(9)], while with the monohydrate (IV), the hydrogen bond involves the partially disordered water molecule which also bridges molecules through both imide and carboxyl O-atom acceptors in a cyclic R4/4(12) association, giving a two-dimensional sheet structure. The structures reported here expand the structural data base for compounds of this series formed from the facile reaction of cis-cyclohexane-1,2-dicarboxylic anhydride with substituted anilines, in which there is a much larger incidence of cyclic imides compared to amide carboxylic acids.

Hydrogen-bonding in the structures of the 1:1 salts of isonipecotamide with a set of four polyfunctional monocyclic heteroaromatic carboxylic acids

The crystal structures of the 1:1 proton-transfer compounds of isonipecotamide (piperidine-4-carboxamide) with the monocyclic heteroaromatic carboxylic acids, isonicotinic acid, picolinic acid, dipicolinic acid and pyrazine-2,3-dicarboxylic acid have been determined at 200 K and their hydrogen-bonding patterns examined. The compounds are respectively anhydrous 4-carbamoylpiperidinium pyridine-4-carboxylate (1), the partial hydrate 4-carbamoylpiperidinium pyridine-2-carboxylate 0.25 water (2), the solvate 4-carbamoylpiperidinium 6-carboxypyridine-2-carboxylate methanol monosolvate (3), and anhydrous 4-carbamoylpiperidinium 3-carboxypyrazine-2-carboxylate (4). In compounds 1 and 3, hydrogen-bonding interactions give two-dimensional sheet structures which feature enlarged cyclic ring systems, while in compounds 2 and 4, three-dimensional structures are found. The previously described cyclic R2/2(8) hydrogen-bonded amide-amide dimer is present in 2 and 3. The hydrogen-bonding in 2 involves the partial-occupancy water molecule while the structure of 4 is based on inter-linked homomolecular hydrogen-bonded cation-cation and anion-anion associated chains comprising head-to-tail interactions. This work further demonstrates the utility of the isonipecotamide cation in the generation of chemically stable hydrogen-bonded systems, particularly with aromatic carboxylate anions, providing crystalline solids.

Omega-3 polyunsaturated fatty acids in the treatment of kidney disease

After more than 25 years of published investigation, including randomized controlled trials, the role of omega-3 polyunsaturated fatty acids in the treatment of kidney disease remains unclear. In vitro and in vivo experimental studies support the efficacy of omega-3 polyunsaturated fatty acids on inflammatory pathways involved with the progression of kidney disease. Clinical investigations have focused predominantly on immunoglobulin A (IgA) nephropathy. More recently, lupus nephritis, polycystic kidney disease, and other glomerular diseases have been investigated. Clinical trials have shown conflicting results for the efficacy of omega-3 polyunsaturated fatty acids in IgA nephropathy, which may relate to varying doses, proportions of eicosapentaenoic acid and docosahexaenoic acid, duration of therapy, and sample size of the study populations. Meta-analyses of clinical trials using omega-3 polyunsaturated fatty acids in IgA nephropathy have been limited by the quality of available studies. However, guidelines suggest that omega-3 polyunsaturated fatty acids should be considered in progressive IgA nephropathy. Omega-3 polyunsaturated fatty acids decrease blood pressure, a known accelerant of kidney disease progression. Well-designed, adequately powered, randomized, controlled clinical trials are required to further investigate the potential benefits of omega-3 polyunsaturated fatty acids on the progression of kidney disease and patient survival.

Structural characterisation and environmental application of organoclays for the removal of phenolic compounds

Modified montmorillonite was prepared at different surfactant (HDTMA) loadings through ion exchange. The conformational arrangement of the loaded surfactants within the interlayer space of MMT was obtained by computational modelling. The conformational change of surfactant molecules enhance the visual understanding of the results obtained from characterization methods such as XRD and surface analysis of the organoclays. Batch experiments were carried out for the adsorption of p-chlorophenol (PCP) and different conditions (pH and temperature) were used in order to determine the optimum sorption. For comparison purpose, the experiments were repeated under the same conditions for p-nitrophenol (PNP). Langmuir and Freundlich equations were applied to the adsorption isotherm of PCP and PNP. The Freundlich isotherm model was found to be the best fit for both of the phenolic compounds. This involved multilayer adsorptions in the adsorption process. In particular, the binding affinity value of PNP was higher than that of PCP and this is attributable to their hydrophobicities. The adsorption of the phenolic compounds by organoclays intercalated with highly loaded surfactants was markedly improved possibly due to the fact that the intercalated surfactant molecules within the interlayer space contribute to the partition phases, which result in greater adsorption of the organic pollutants.

The individual and interactive relationship between long chain omega-3 polyunsaturated fatty acids and physical activity as predictors of cognition in cognitively impaired and non-impaired older adults

Alterations in cognitive function are characteristic of the aging process in humans and other animals. However, the nature of these age related changes in cognition is complex and is likely to be influenced by interactions between genetic predispositions and environmental factors resulting in dynamic fluctuations within and between individuals. These inter and intra-individual fluctuations are evident in both so-called normal cognitive aging and at the onset of cognitive pathology. Mild Cognitive Impairment (MCI), thought to be a prodromal phase of dementia, represents perhaps the final opportunity to mitigate cognitive declines that may lead to terminal conditions such as dementia. The prognosis for people with MCI is mixed with the evidence suggesting that many will remain stable within 10-years of diagnosis, many will improve, and many will transition to dementia. If the characteristics of people who do not progress to dementia from MCI can be identified and replicated in others it may be possible to reduce or delay dementia onset, thus reducing a growing personal and public health burden. Furthermore, if MCI onset can be prevented or delayed, the burden of cognitive decline in aging populations worldwide may be reduced. A cognitive domain that is sensitive to the effects of advancing age, and declines in which have been shown to presage the onset of dementia in MCI patients, is executive function. Moreover, environmental factors such as diet and physical activity have been shown to affect performance on tests of executive function. For example, improvements in executive function have been demonstrated as a result of increased aerobic and anaerobic physical activity and, although the evidence is not as strong, findings from dietary interventions suggest certain nutrients may preserve or improve executive functions in old age. These encouraging findings have been demonstrated in older adults with MCI and their non-impaired peers. However, there are some gaps in the literature that need to be addressed. For example, little is known about the effect on cognition of an interaction between diet and physical activity. Both are important contributors to health and wellbeing, and a growing body of evidence attests to their importance in mental and cognitive health in aging individuals. Yet physical activity and diet are rarely considered together in the context of cognitive function. There is also little known about potential underlying biological mechanisms that might explain the physical activity/diet/cognition relationship. The first aim of this program of research was to examine the individual and interactive role of physical activity and diet, specifically long chain polyunsaturated fatty acid consumption(LCn3) as predictors of MCI status. The second aim is to examine executive function in MCI in the context of the individual and interactive effects of physical activity and LCn3.. A third aim was to explore the role of immune and endocrine system biomarkers as possible mediators in the relationship between LCn3, physical activity and cognition. Study 1a was a cross-sectional analysis of MCI status as a function of erythrocyte proportions of an interaction between physical activity and LCn3. The marine based LCn3s eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have both received support in the literature as having cognitive benefits, although comparisons of the relative benefits of EPA or DHA, particularly in relation to the aetiology of MCI, are rare. Furthermore, a limited amount of research has examined the cognitive benefits of physical activity in terms of MCI onset. No studies have examined the potential interactive benefits of physical activity and either EPA or DHA. Eighty-four male and female adults aged 65 to 87 years, 50 with MCI and 34 without, participated in Study 1a. A logistic binary regression was conducted with MCI status as a dependent variable, and the individual and interactive relationships between physical activity and either EPA or DHA as predictors. Physical activity was measured using a questionnaire and specific physical activity categories were weighted according to the metabolic equivalents (METs) of each activity to create a physical activity intensity index (PAI). A significant relationship was identified between MCI outcome and the interaction between the PAI and EPA; participants with a higher PAI and higher erythrocyte proportions of EPA were more likely to be classified as non-MCI than their less active peers with less EPA. Study 1b was a randomised control trial using the participants from Study 1a who were identified with MCI. Given the importance of executive function as a determinant of progression to more severe forms of cognitive impairment and dementia, Study 1b aimed to examine the individual and interactive effect of physical activity and supplementation with either EPA or DHA on executive function in a sample of older adults with MCI. Fifty male and female participants were randomly allocated to supplementation groups to receive 6-months of supplementation with EPA, or DHA, or linoleic acid (LA), a long chain polyunsaturated omega-6 fatty acid not known for its cognitive enhancing properties. Physical activity was measured using the PAI from Study 1a at baseline and follow-up. Executive function was measured using five tests thought to measure different executive function domains. Erythrocyte proportions of EPA and DHA were higher at follow-up; however, PAI was not significantly different. There was also a significant improvement in three of the five executive function tests at follow-up. However, regression analyses revealed that none of the variance in executive function at follow-up was predicted by EPA, DHA, PAI, the EPA by PAI interaction, or the DHA by PAI interaction. The absence of an effect may be due to a small sample resulting in limited power to find an effect, the lack of change in physical activity over time in terms of volume and/or intensity, or a combination of both reduced power and no change in physical activity. Study 2a was a cross-sectional study using cognitively unimpaired older adults to examine the individual and interactive effects of LCn3 and PAI on executive function. Several possible explanations for the absence of an effect were identified. From this consideration of alternative explanations it was hypothesised that post-onset interventions with LCn3 either alone or in interation with self-reported physical activity may not be beneficial in MCI. Thus executive function responses to the individual and interactive effects of physical activity and LCn3 were examined in a sample of older male and female adults without cognitive impairment (n = 50). A further aim of study 2a was to operationalise executive function using principal components analysis (PCA) of several executive function tests. This approach was used firstly as a data reduction technique to overcome the task impurity problem, and secondly to examine the executive function structure of the sample for evidence of de-differentiation. Two executive function components were identified as a result of the PCA (EF 1 and EF 2). However, EPA, DHA, the PAI, or the EPA by PAI or DHA by PAI interactions did not account for any variance in the executive function components in subsequent hierarchical multiple regressions. Study 2b was an exploratory correlational study designed to explore the possibility that immune and endocrine system biomarkers may act as mediators of the relationship between LCn3, PAI, the interaction between LCn3 and PAI, and executive functions. Insulin-like growth factor-1 (IGF-1), an endocrine system growth hormone, and interleukin-6 (IL-6) an immune system cytokine involved in the acute inflammatory response, have both been shown to affect cognition including executive functions. Moreover, IGF-1 and IL-6 have been shown to be antithetical in so far as chronically increased IL-6 has been associated with reduced IGF-1 levels, a relationship that has been linked to age related morbidity. Further, physical activity and LCn3 have been shown to modulate levels of both IGF-1 and IL-6. Thus, it is possible that the cognitive enhancing effects of LCn3, physical activity or their interaction are mediated by changes in the balance between IL-6 and IGF-1. Partial and non-parametric correlations were conducted in a subsample of participants from Study 2a (n = 13) to explore these relationships. Correlations of interest did not reach significance; however, the coefficients were quite large for several relationships suggesting studies with larger samples may be warranted. In summary, the current program of research found some evidence supporting an interaction between EPA, not DHA, and higher energy expenditure via physical activity in differentiating between older adults with and without MCI. However, a RCT examining executive function in older adults with MCI found no support for increasing EPA or DHA while maintaining current levels of energy expenditure. Furthermore, a cross-sectional study examining executive function in older adults without MCI found no support for better executive function performance as a function of increased EPA or DHA consumption, greater energy expenditure via physical activity or an interaction between physical activity and either EPA or DHA. Finally, an examination of endocrine and immune system biomarkers revealed promising relationships in terms of executive function in non-MCI older adults particularly with respect to LCn3 and physical activity. Taken together, these findings demonstrate a potential benefit of increasing physical activity and LCn3 consumption, particularly EPA, in mitigating the risk of developing MCI. In contrast, no support was found for a benefit to executive function as a result of increased physical activity, LCn3 consumption or an interaction between physical activity and LCn3, in participants with and without MCI. These results are discussed with reference to previous findings in the literature including possible limitations and opportunities for future research.

Mass spectrometric study of the dissociation of Group XI metal complexes with fatty acids and glycerolipids : Ag2H+ and Cu2H+ ion formation in the presence of a double bond

Results of mass spectrometric studies are reported for the collisional dissociation of Group XI (Cu, Ag, Au) metal ion complexes with fatty acids (palmitic, oleic, linoleic and a-linolenic) and glycerolipids. Remarkably, the formation of M2H+ ions (M = Cu, Ag) is observed as a dissociation product of the ion complexes containing more than one metal cation and only if the lipid in the complex contains a double bond. Ag2H+ is formed as the main dissociation channel for all three of the fatty acids containing double bonds that were investigated while Cu2H+ is formed with one of the fatty acids and, although abundant, is not the dominant dissociation channel. Also. Cu(I) and Ag(I) ion complexes were observed with glycerolipids (including triacylglycerols and glycerophospholipids) containing either saturated or unsaturated fatty acid substituents. Interestingly. Ag2H+ ion is formed in a major fragmentation channel with the lipids that are able to form the complex with two metal cations (triacylglycerols and glycerophosphoglycerols), while lipids containing a fixed positive charge (glycerophospocholines) complex only with a single metal cation. The formation of Ag2H+ ion is a significant dissociation channel from the complex ion Ag-2(L-H)(+) where L = Glycerophospholipid (GP) (18:1/18:1). Cu(I) also forms complexes of two metal cations with glycerophospholipids but these do not produce Cu2H+ upon dissociation. Rather organic fragments, not containing Cu(I), are formed, perhaps due to different interactions of these metal cations with lipids resulting from the much smaller ionic radius of Cu(I) compared to Ag(I) (C).

Preparative deracemization of unnatural amino acids

Unnatural amino acids are a growing class of intermediates required for pharmaceuticals, agrochemicals and other industrial products. However, no single method has proven sufficiently versatile to prepare these compounds broadly at scale. To address this need, we have developed a general chemoenzymatic process to prepare enantiomerically pure L- and D-amino acids in high yield by deracemization of racemic starting materials. This method involves the concerted action of an enantioselective oxidase biocatalyst and a non-selective chemical reducing agent to effect the stereoinversion of one enantiomer and can result in an enantiomeric excess of >99% from the starting racemate, and product yields of over 90%. This approach compares very favourably with resolution processes, which have a maximum single-pass yield of 50%. We have developed efficient methods to adapt the process towards new target compounds and to optimize key factors that influence process efficiency and offer competitive economics at scale.