19 resultados para Substitutions

em Deakin Research Online - Australia


Relevância:

10.00% 10.00%

Publicador:

Resumo:

■ Human well-being has several key components: the basic material needs for a good life, freedom and choice, health, good social relations, and personal security. Well-being exists on a continuum with poverty, which has been defined as"pronounced deprivation in well-being."
■ How well-being and ill-being, or poverty, are expressed and experienced is context- and situation-dependent, reflecting local social and personal factors such as geography, ecology, age, gender,and culture.These concepts are complex and value-laden.
■ Ecosystems are essential for human well-being through their provisioning, regulating, cultural, and supporting services. Evidence in recent decades of escalating human impacts. on ecological systems worldwide raises concerns about the consequences of ecosystem changes for human well-being.
■ Human well-being can be enhanced through sustainable human interaction with ecosystems with the support of appropriate instruments, institutions, organizations, and technology. creation of these through participation and transparency may contribute to people's freedoms and choices and to increased economic, social,and ecological security.
■ Some believe that the problems from the depletion and degradation of ecological capital can be largely overcome by the substitution of physical and human capital. Others believe that there are more significant limits to such substitutions.The scope for substitutions varies by socioeconomic status.
■ We identify direct and indirect pathways between ecosystem change and human well-being,whether it be positive or negative.lndirect effects are characterized by more complex webs of causation, involving social, economic, and political threads. Threshold points exist beyond which rapid changes to human well-being can occur.
■ Indigent poorly resourced, and otherwise disadvantaged communities are generally the most vulnerable to adverse ecosystem change. Spirals, both positive and negative, can occur for any population, but the poor are more vulnerable.      
■ Functioning institutions are vital to enable equitable access to ecosystem services. lnstitutions sometimes fail or remain undeveloped because of powerful individuals or groups. Bodies that mediate the distribution of goods and services may also be appropriated for the benefit of powerful minorities.
■ For poor people, the greatest gains in well-being will occur through more equitable and secure access to ecosystem services. In the long run, the rich can contribute greatly to human well-being by reducing their substantial impacts on ecosystems and by facilitating greater access to ecosystem services by the poor.
■ We argue ecological security warrants recognition as a sixth freedom of equal weight with participative freedom, economic   facilities, social opportunities, transparency guarantees, and protective security.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

This study aimed to assess the dietary changes that occur for migrants moving from a low-income to a high-income country. The sample included 45 females who had migrated to Australia from Somalia within the past 5years (1996-2001). The data for the study was derived from structured interviews conducted by a bilingual interviewer and anthropometry. Usual dietary intake and frequency of consumption of 54 foods were determined both for Australia (current home) and for Somalia (previous home). In Australia, subjects maintained the structure of the diet from their country of birth. They did increase their consumption of some processed food, such as instant noodles, crisps, and pizza. However, there was little evidence that the subjects adopted ready or partially prepared meals or takeaway meals. A significant addition to the diet in Australia was the use of breakfast cereals. Significant substitutions were of ready-baked bread for traditional bread and lamb for camel meat. The mean BMI of the sample was 27.4kg/m2. Sixty percent of the sample were overweight or obese (BMI>25). Some of the dietary changes observed may be consistent with increased energy intake and altered nutrient density. Given the association between transition to a high-income diet and obesity, it is important that migrants are encouraged to retain the best of their traditional diet while adopting healthy foods from host country.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Fish of the genus Gadopsis are a distinctive component of the freshwater fish fauna of south-eastern Australia. Gadopsis marmoratus and G. bispinosus are the only two species recognised within the genus, with the former of uncertain taxonomic status, as it is thought to be composed of at least two distinct geographical forms based on morphological and allozyme data. The objective of this study was to investigate DNA sequence divergence in Gadopsis, especially in the western portion of its distribution, using an approximately 400 base pair fragment of the mitochondrial small subunit 12S rRNA gene region in order to reassess the taxonomy of the genus. Individuals from 11 locations were sequenced and confirm that G. marmoratus and G. bispinosus are genetically distinct, and further that the G. marmoratus complex consists of two divergent clades representing the previously identified northern and southern forms. The degree of divergence between the three Gadopsis clades was similar (5–6% nucleotide substitutions), suggesting that they diverged from a common ancestor at approximately the same period in geological time. These results are consistent with previous allozyme studies and highlight the usefulness of mitochondrial DNA data coupled with allozyme information for clarifying taxonomic boundaries in morphologically conservative aquatic organisms.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Atrial natriuretic peptide (ANP) and B-type NP (BNP) are hormones involved in homeostatic control of body fluid and cardiovascular regulation. Both ANP and BNP have been cloned from the heart of mammals, amphibians, and teleost fishes, while an additional cardiac peptide, ventricular NP, has been found in selected species of teleost fish. However, in chicken, BNP is the primary cardiac peptide identified thus far. In contrast, the types of NP/s present in the reptilian heart are unknown, representing a considerable gap in our understanding of NP evolution. In the present study, we cloned and sequenced a BNP cDNA from the atria of representative species of reptile, including crocodile, lizard, snake, and tortoise. In addition, we cloned BNP from the pigeon atria. The reptilian and pigeon BNP cDNAs had ATTTA repeats in the 3′ untranslated region, as observed in all vertebrate BNP mRNAs. A high sequence homology was evident when comparing reptile and pigeon preproBNP with the previously identified chicken preproBNP. In particular, the predicted mature BNP-29 was identical between crocodile, tortoise, and chicken, with pigeon having a single amino acid substitution; lizard and snake BNP had seven and nine substitutions, respectively. Furthermore, an ANP cDNA could only be cloned from the tortoise atria. Since ANP was not isolated from the heart of any non-chelonian reptile and appears to be absent in birds, we propose that the ANP gene has been lost after branching of the turtles in the amniote line. This data provides new avenues for research on NP function in reptiles.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Electrophilic substitution of acylmethanes (methyl ketones), RCOCH3 (R = i-Pr, 1; Et, 2; Me, 3) with aryltellurium trichlorides, ArTeCl3 (Ar = 1-C10H7, Np, A; 2,4,6-Me3C6H2, Mes, B; 4-MeOC6H4, Anisyl, C) under mild conditions affords the corresponding acylmethyl(aryl)tellurium dichlorides (RCOCH2)ArTeCl2. Reduction of the dichlorides, gives tellurides, (i-PrCOCH2)ArTe, 1A–1C, which give the corresponding dihalides, (i-PrCOCH2)ArTeX2 (X = Cl, 1Aa–1Ca; Br, 1Ab–1Cb; I, 1Ac–1Cc) when reacted in situ with SO2Cl2, Br2 or I2. The unsymmetric tellurides are labile towards disproportionation and attempts to obtain them lead to the isolation of Ar2Te2 except in the case of (i-PrCOCH2)MesTe ( 1B), which represents an interesting example of a kinetically stable aryl(alkyl)telluride. All the dihalomesityltellurium(IV) derivatives show separate 1H and 13C NMR signals for the ortho methyls irrespective of the sizes of R and X ligands. The telluride, 1B with free rotation about Te–C(mesityl) bond shows, like the unsymmetric diorganotellurium(IV) dihalides, only one 125Te NMR signal. The 1,4-chelating behavior of the acyl ligand among diorganotellurium(IV) compounds is inferred from the X-ray diffraction data for 1Aa, 1Ac, 1Ba, 1Bb, 1Ca and 1Cc which are indicative of the presence of intramolecular TeO secondary bonding interactions (SBIs) at least in the solid state. As a consequence, steric repulsion in case of the mesityltellurium(IV) derivatives, 1Ba and 1Bb, reaches the threshold so as to cause loss of two-fold rotational symmetry of the mesityl group about the Te–C(mesityl) bond axis. Intermolecular C–HO H-bonding interactions appears to stabilize such an orientation of the aryl ligand at least in the solid state.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Hev b 6.01 is a major allergen of natural rubber latex with sensitization of 70–86% of latex glove-allergic subjects. Recently, we mapped the immunodominant T cell sites of Hev b 6.01 to the highly IgE-reactive hevein (Hev b 6.02) domain. Hev b 6.01 contains 14 cysteine residues with multiple disulphide bridges stabilizing tertiary conformation. With the goal of a standardized specific immunotherapy we developed hypoallergenic Hev b 6.01 mutants by site-directed mutagenesis of selected cysteine residues (3, 12, 17, and 41) within the Hev b 6.02 domain. Peptides corresponding to the Hev b 6.02 domain of two of the mutants were also synthesized. These mutants and peptide variants showed markedly decreased or ablated latex-allergic patient serum IgE binding by immunoblotting and ELISA. Basophil activation testing confirmed markedly decreased activation with successive cysteine substitutions of the mutants and complete abrogation with the Hev b 6.02 (Cys 3, 12, 17, 41 Ala) peptide. Retention of T cell reactivity is crucial for effective specific immunotherapy and all mutants and peptide variants maintained their latex-specific T cell reactivity. The ablated allergenicity but retained T cell reactivity of the Hev b 6.02 (Cys 3, 12, 17, 41 Ala) peptide suggests this peptide is a suitable candidate for inclusion in a latex immunotherapy preparation.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

N-Ethylcarboxamidoadenosine (12) was synthesised from adenosine (1) and the 6-chloro-2’,3’-O-isopropylidene-AT-ethylcarboxamidoadenosine (25) was synthesised from inosine (19). Employing molecular modelling techniques and the results from previous structure activity relationships it was possible to design and synthesise a N6-substituted N-ethylcarboxamidoadenosines which possessed an oxygen in the N6-substituent either in the form of an epoxide (which was obtained by cpoxidising an alkene with m-CPBA or dimethyldioxirane) or in the form of a cyclic ether as was the case for N6-((tetrahydro-2H--pyran--2-yl)methyl-N-ethylcarboxamidoadenosine (78). These compounds were tested for their biological activity at the A1 adenosine receptor by their ability to inhibit cAMP accumulation in DDT, MF2 cells. The EC50 values obtained indicated that the N6-(norborn-5-en-2-yl)-N-ethylcarboxamidoadenosines were the most potent. Of theseN6-(S-endo-norbrn-5-en-2-yI)-N-ethylcarboxaniidoadenosine (56) was the most potent (0.2 nM). N6-(exo-norborn-5-en-2-yl)-2-iodo-N-ethylcarboxamidoadenosine (79) was synthesised from guanosine (22) and was also evaluated for its potency at the A, receptor (24.8 ± 1.5 nM). At present 79 is being evaluated for its selectivity for the A1 receptor compared to the other three receptor subtypes (A2a, A2b, A3). A series of N6-(benzyl)-N-ethylcarboxamidoadenosines were synthesised with substitutions at the 4-position of the phenyl ring. Another series of compounds were synthesised which replaced the methylene spacer between the N6H and the N6-aromatic or lipophilic substituent The replacement groups -were carbonyl and trans-2- cyclopropyl moieties. The N6-acyl compounds were obtained by reacting 2’,3’-O- di(tert-butyldimethylsilyl)-AT-ethylcarboxamidoadenosinc (59) with the appropriate acid chloride and then deprotecting with lelrabutylammonium fluoride in tetrahydrofuran. The compound N6-(4-(1,2-dihydroxy)ethyl)benzyl-N- ethylcarboxamidoadenosine (125) was synthesised by the reaction of 4-(1,2-0- isopropylidene-ethyl)benzyl aminc (123) with 6-chloro-2,3-0-isopropylidene-N- ethylcarboxamidoadenosine (25). Compound 123 was synthesised from an epoxidation of vinylbenzyl phthalimide (118) followed by an acidic ring opening to yield the diol which was isopropylidenated to yield 4-(l,2-O-isopropylidene- elhyl)benzyl phlhalimide (122), It was hoped that the presence of the diol functionality in 125 would increase water solubility whilst maintaining potency at the A3 receptor.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Lithium ion conducting ceramics based on the lithium aluminium titanium phosphate (LATP) NASICON structure have been prepared with various substitutions of the phosphorous. The effect of the processing method has been shown to be the key factor in determining the conductivity, both bulk and grain boundary, as well as the conductivity trends observed as a function of substitution.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

A combination of X-ray powder diffraction (XRD) and nuclear magnetic resonance (NMR) studies has demonstrated that attempted substitutions of Al, V and Nb into the framework of LiTi2(PO4)3 yield several impurity phases in addition to direct substitutions of Al into Ti and V, Nb into P sites. Direct substitutions were confirmed by changes in the unit cell dimensions as indicated by the peak shifts observed in the X-ray diffractographs and by analyses of the 27Al and 31P magic angle spinning (MAS) spectra. A major impurity phase was identified as AlPO4 (found in at least two polymorphs) and the amount present increases with increasing Al additions. The formation of AlPO4 appeared to be enhanced by further V but suppressed by Nb substitution. These results suggest that the presence of AlPO4 , together with the non-stoichiometric modified LTP, may be the cause for the observed densification of this material upon sintering and the increased ionic conductivity.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Angiotensin (Ang) I-converting enzyme (ACE) is a Zn2+ metalloprotease with two homologous catalytic domains. Both the N- and C-terminal domains are peptidyl dipeptidases. Hydrolysis by ACE of its decapeptide substrate Ang I is increased by Cl−, but the molecular mechanism of this regulation is unclear. A search for single substitutions to Gln among all conserved basic residues (Lys/Arg) in human ACE C-domain identified R1098Q as the sole mutant that lacked Cl− dependence. Cl−dependence is also lost when the equivalent Arg in the N-domain, Arg500, is substituted with Gln. The Arg1098 to Lys substitution reduced Cl− binding affinity by ∼100-fold. In the absence of Cl−, substrate binding affinity (1/K m) of and catalytic efficiency (k cat/K m) for Ang I hydrolysis are increased 6.9- and 32-fold, respectively, by the Arg1098 to Gln substitution, and are similar (<2-fold difference) to the respective wild-type C-domain catalytic constants in the presence of optimal [Cl−]. The Arg1098 to Gln substitution also eliminates Cl− dependence for hydrolysis of tetrapeptide substrates, but activity toward these substrates is similar to that of the wild-type C-domain in the absence of Cl−. These findings indicate that: 1) Arg1098 is a critical residue of the C-domain Cl−-binding site and 2) a basic side chain is necessary for Cl− dependence. For tetrapeptide substrates, the inability of R1098Q to recreate the high affinity state generated by the Cl−-C-domain interaction suggests that substrate interactions with the enzyme-bound Cl− are much more important for the hydrolysis of short substrates than for Ang I. Since Cl− concentrations are saturating under physiological conditions and Arg1098 is not critical for Ang I hydrolysis, we speculate that the evolutionary pressure for the maintenance of the Cl−-binding site is its ability to allow cleavage of short cognate peptide substrates at high catalytic efficiencies.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Background and Purpose: Evaluate self-initiated pretend play of children with cerebral palsy.

Method: Twenty preschool children participated in the study. Pretend play ability was measured by using the child-initiated pretend play assessment culturally adapted to Brazil.

Results: There were significant negative correlations between the children’s motor severity level and their elaborateness of play with conventionalimaginative and symbolic play materials and a number of object substitutions in symbolic play. This indicated that children with greater motor limitations had diminished play ability. In this sample, 35% of the children showed typical play styles, identified by good scores in elaborate pretend play actions, number of object substitutions, and ability to self-initiate play, whereas 65% showed delay in their play.

Implications: The type of pretend play deficits that might be expected in children with cerebral palsy were described. Furthermore, suggested directions for therapeutic intervention to enhance pretend play performance in cerebral palsy children were proposed.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Screening of a genomic library of the thermophile Thermus thermophilus revealed a novel thermophilic hint gene, homologues of which are highly conserved in genera from archaea to mammals. Hint belongs to the HIT protein super-family, which contains two broad groups, Fhit, associated with tumour suppression in eukaryotes and Hint with putatitive protein kinase C inhibitory activity. In T. thermophilus the 321bp gene has a GC content of 67% overall and 94.4% in the third nucleotide position, with unusually no thymine as a wobble base. The gene product, a small highly conserved 11996Da predicted soluble cytoplasmic protein, offers an ideal opportunity to investigate thermostabilising amino acid substitutions. Here we report on the characterisation of the novel hint sequence.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Since their introduction to the toad-free Australian continent cane toads (Bufo marinus) have caused a dramatic increase in naïve varanid mortality when these large lizards attempt to feed on this toxic amphibian. In contrast Asian–African varanids, which have coevolved with toads, are resistant to toad toxin. Toad toxins, such as Bufalin target the H1-H2 domain of the α1 subunit of the sodium-potassium-ATPase enzyme. Sequencing of this domain revealed identical nucleotide sequences in four Asian as well as in three African varanids, and identical sequences in all 11 Australian varanids. However, compared to the Asian–African varanids, the Australian varanids showed four-base-pair substitutions, resulting in the alteration in three of the 12 amino acids representing the H1-H2 domain. The phenotypic effect of the substitutions was investigated in human embryonic kidney (HEK) 293 cells stably transfected with the Australian and the Asian–African H1-H2 domains. The transfections resulted in an approximate 3000-fold reduction in resistance to Bufalin in the Australian HEK293 cells compared to the Asian–African HEK293 cells, demonstrating the critical role of this minor mutation in providing Bufalin resistance. Our study hence presents a clear link between genotype and phenotype, a critical step in understanding the evolution of phenotypic diversity.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

BACKGROUND: We describe Pseudomonas aeruginosa acquisitions in children with cystic fibrosis (CF) aged ≤5-years, eradication treatment efficacy, and genotypic relationships between upper and lower airway isolates and strains from non-CF sources. METHODS: Of 168 CF children aged ≤5-years in a bronchoalveolar lavage (BAL)-directed therapy trial, 155 had detailed microbiological results. Overall, 201/271 (74%) P. aeruginosa isolates from BAL and oropharyngeal cultures were available for genotyping, including those collected before and after eradication therapy. RESULTS: Eighty-two (53%) subjects acquired P. aeruginosa, of which most were unique strains. Initial eradication success rate was 90%, but 36 (44%) reacquired P. aeruginosa, with genotypic substitutions more common in BAL (12/14) than oropharyngeal (3/11) cultures. Moreover, oropharyngeal cultures did not predict BAL genotypes reliably. CONCLUSIONS: CF children acquire environmental P. aeruginosa strains frequently. However, discordance between BAL and oropharyngeal strains raises questions over upper airway reservoirs and how to best determine eradication in non-expectorating children.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

An experimental study has been performed to investigate the ignition delay of a modern heavy-duty common-rail diesel engine run with fumigated ethanol substitutions up to 40% on an energy basis. The ignition delay was determined through the use of statistical modelling in a Bayesian framework this framework allows for the accurate determination of the start of combustion from single consecutive cycles and does not require any differentiation of the in-cylinder pressure signal. At full load the ignition delay has been shown to decrease with increasing ethanol substitutions and evidence of combustion with high ethanol substitutions prior to diesel injection have also been shown experimentally and by modelling. Whereas, at half load increasing ethanol substitutions have increased the ignition delay. A threshold absolute air to fuel ratio (mole basis) of above ~110 for consistent operation has been determined from the inter-cycle variability of the ignition delay, a result that agrees well with previous research of other in-cylinder parameters and further highlights the correlation between the air to fuel ratio and inter-cycle variability. Numerical modelling to investigate the sensitivity of ethanol combustion has also been performed. It has been shown that ethanol combustion is sensitive to the initial air temperature around the feasible operating conditions of the engine. Moreover, a negative temperature coefficient region of approximately 900{1050 K (the approximate temperature at fuel injection) has been shown with for n-heptane and n-heptane/ethanol blends in the numerical modelling. A consequence of this is that the dominate effect influencing the ignition delay under increasing ethanol substitutions may rather be from an increase in chemical reactions and not from in-cylinder temperature. Further investigation revealed that the chemical reactions at low ethanol substitutions are different compared to the high (> 20%) ethanol substitutions.