Inter-Bragg crystallographic phase retrieval from shape transforms, stacking faults and substitutional disorder

One of the brilliant ideas of John Spence when he saw the first diffraction patterns from the Linac Coherent Light Source was that one could solve the crystallographic phase problem by utilising the intensities between Bragg peaks. Because these intensities are due to the Fourier transform of the shape of the crystal, the approach came to be known as "shape-transform phasing." Shape-transform phasing was developed over the next ten years and formed the basis for many other interesting ideas and pursuits. Here we describe the current best implementation of the original idea using a lattice occupancy formalism and show that certain types of crystal defects can also be modelled via this approach, allowing the molecular structure to be recovered from the additional information offered by the inter-Bragg intensities from these crystal defects.

AXSIS: Exploring the frontiers in attosecond X-ray science, imaging and spectroscopy

X-ray crystallography is one of the main methods to determine atomic-resolution 3D images of the whole spectrum of molecules ranging from small inorganic clusters to large protein complexes consisting of hundred-thousands of atoms that constitute the macromolecular machinery of life. Life is not static, and unravelling the structure and dynamics of the most important reactions in chemistry and biology is essential to uncover their mechanism. Many of these reactions, including photosynthesis which drives our biosphere, are light induced and occur on ultrafast timescales. These have been studied with high time resolution primarily by optical spectroscopy, enabled by ultrafast laser technology, but they reduce the vast complexity of the process to a few reaction coordinates. In the AXSIS project at CFEL in Hamburg, funded by the European Research Council, we develop the new method of attosecond serial X-ray crystallography and spectroscopy, to give a full description of ultrafast processes atomically resolved in real space and on the electronic energy landscape, from co-measurement of X-ray and optical spectra, and X-ray diffraction. This technique will revolutionize our understanding of structure and function at the atomic and molecular level and thereby unravel fundamental processes in chemistry and biology like energy conversion processes. For that purpose, we develop a compact, fully coherent, THz-driven atto-second X-ray source based on coherent inverse Compton scattering off a free-electron crystal, to outrun radiation damage effects due to the necessary high X-ray irradiance required to acquire diffraction signals. This highly synergistic project starts from a completely clean slate rather than conforming to the specifications of a large free-electron laser (FEL) user facility, to optimize the entire instrumentation towards fundamental measurements of the mechanism of light absorption and excitation energy transfer. A multidisciplinary team formed by laser-, accelerator,- X-ray scientists as well as spectroscopists and biochemists optimizes X-ray pulse parameters, in tandem with sample delivery, crystal size, and advanced X-ray detectors. Ultimately, the new capability, attosecond serial X-ray crystallography and spectroscopy, will be applied to one of the most important problems in structural biology, which is to elucidate the dynamics of light reactions, electron transfer and protein structure in photosynthesis.

Pronociceptive effects induced by cutaneous application of a transient receptor potential ankyrin 1 (TRPA1) channel agonist methylglyoxal in diabetic animals: comparison with tunicamycin-induced endoplastic reticulum stress

Methylglyoxal (MG) is a reactive carbonyl compound generated in diabetes mellitus. MG is an established transient receptor potential ankyrin 1 (TRPA1) channel agonist that contributes to TRPA1-mediated diabetic pain hypersensitivity. Here we studied whether exposure to diabetes and thereby to elevated endogenous MG modulates hypersensitivity induced by intradermal MG. Moreover, since diabetes induces endoplasmic reticulum (ER) stress, we compared the role of TRPA1 in diabetes and ER stress by assessing whether tunicamycin-induced ER stress, without diabetes, produces TRPA1-mediated pain hypersensitivity and by assessing whether ER stress and diabetes have similar modulatory effects on MG-induced hypersensitivity. In vitro patch clamp recording was performed to assess whether tunicamycin is a TRPA1 agonist. Behavioral tests showed that mechanical hypersensitivity induced by MG is reduced in diabetes and ER stress. In healthy controls, hypersensitivity induced by MG was reduced when MG was administered for the second time in the same but not adjacent plantar sites. Hypersensitivity induced by ER stress was reversed by pharmacological blocking of TRPA1. In vitro patch clamp recording indicated that tunicamycin itself (30 μM) is not a TRPA1 agonist. The results indicate that pain hypersensitivity induced by non-diabetic ER stress as well as that induced by diabetes is mediated TRPA1. Reduction of MG-induced hypersensitivity in diabetes or ER stress may, at least partly, be explained by peripheral mechanisms.

Contact sensitizer 2,4-dinitrochlorobenzene is a highly potent human TRPA1 agonist

2,4-Dinitrochlorobenzene (DNCB) is widely used in human clinical studies and in experimental animal studies to evoke allergic contact dermatitis. 2,4-Dinitrochlorobenzene is a potent immunogen capable of inducing contact sensitization in all humans exposed. However, the mechanism by which DNCB evokes such symptoms is presently unknown. TRPA1 is a nonselective cation channel that is expressed in peptidergic sensory neurons and fibroblasts. TRPA1 activation was recently implicated in the pathophysiology of atopic dermatitis especially in transducing cutaneous itch signals. Here, we test the hypothesis that DNCB acts as a TRPA1 agonist and thereby evokes allergic symptoms. We found that DNCB activates human TRPA1 dose dependently in FLIPR experiments with an EC50 of 167 nM, an effect that was fully blocked by selective TRPA1 antagonists Chembridge-5861528 and A-967079. Similarly, DNCB activated nonselective TRPA1 current in patch clamp studies. Neutralization of 3 critical cysteines in TRPA1 resulted in a loss of DNCB agonism.

Source apportionment of heavy metals and ionic contaminants in rainwater tanks in a subtropical urban area in Australia

Due to prolonged droughts in recent years, the use of rainwater tanks in urban areas has increased in Australia. In order to apportion sources of contribution to heavy metal and ionic contaminants in rainwater tanks in Brisbane, a subtropical urban area in Australia, monthly tank water samples (24 sites, 31 tanks) and concurrent bulk deposition samples (18 sites) were collected during mainly April 2007-March 2008. The samples were analysed for acid-soluble metals, soluble anions, total inorganic carbon and total organic carbon, and characteristics such as total solid and pH. The Positive Matrix Factorisation model, EPA PMF 3.0, was used to apportion sources of contribution to the contaminants. Four source factors were identified for the bulk deposition samples, including 'crustal matter/sea salt', 'car exhausts/road side dust', 'industrial dust' and 'aged sea salt/secondary aerosols'. For the tank water samples, apart from these atmospheric deposition related factors which contributed in total to 65% of the total contaminant concentration on average, another six rainwater collection system related factors were identified, including 'plumbing', 'building material', 'galvanizing', 'roofing', 'steel' and 'lead flashing/paint' (contributing in total to 35% of the total concentration on average). The Australian Drinking Water Guideline for lead was exceeded in 15% of the tank water samples. The collection system related factors, in particular the 'lead flashing/paint' factor, contributed to 79% of the lead in the tank water samples on average. The concentration of lead in tank water was found to vary with various environmental and collection system factors, in particular the presence of lead flashing on the roof. The results also indicated the important role of sludge dynamics inside the tank on the quality of tank water.

Soft x-ray free electron laser microfocus for exploring matter under extreme conditions

We have focused a beam (BL3) of FLASH (Free-electron LASer in Hamburg: lambda = 13.5 nm, pulse length 15 fs, pulse energy 10-40 microJ, 5 Hz) using a fine polished off-axis parabola having a focal length of 270 mm and coated with a Mo/Si multilayer with an initial reflectivity of 67% at 13.5 nm. The OAP was mounted and aligned with a picomotor controlled six-axis gimbal. Beam imprints on poly(methyl methacrylate) - PMMA were used to measure focus and the focused beam was used to create isochoric heating of various slab targets. Results show the focal spot has a diameter of < or =1 microm. Observations were correlated with simulations of best focus to provide further relevant information.

Characterisation of atmospheric deposition as a source of contaminants in urban rainwater tanks

To characterise atmospheric input of chemical contaminants to urban rainwater tanks, bulk deposition (wet+dry deposition) was collected at sixteen sites in Brisbane, Queensland, Australia on a monthly basis during April 2007-March 2008 (N=175). Water from rainwater tanks (22 sites, 26 tanks) was also sampled concurrently. The deposition/tank water was analysed for metals, soluble anions and selected samples were additionally analysed for PAHs, pesticides, phenols, organic & inorganic carbon. Flux (mg/m(2)/d) of total solids mass was found to correlate with average daily rainfall (R(2)=0.49) indicating the dominance of the wet deposition contribution to total solids mass. On average 97% of the total mass of analysed components was accounted for by Cl(-) (25.0%), Na (22.6%), organic carbon (20.5%), NO(3)(-) (10.5%), SO(4)(2-) (9.8%), inorganic carbon (5.7%), PO(4)(3-) (1.6%) and NO(2)(-) (1.5%). For other minor elements the average flux from highest to lowest was in the order of Fe>Al>Zn>Mn>Sr>Pb>Ba>Cu>Se. There was a significant effect of location on flux of K, Sb, Sn, Li, Mn, Fe, Cu, Zn, Ba, Pb and SO(4)(2-) but not other metals or anions. Overall the water quality resulting from the deposition (wet+dry) was good but 10.3%, 1.7% and 17.7% of samples had concentrations of Pb, Cd and Fe respectively greater than the Australian Drinking Water Guidelines (ADWG). This generally occurred in the drier months. In comparison 14.2% and 6.1% of tank samples had total Pb and Zn concentrations exceeding the guidelines. The cumulative mean concentration of lead in deposition was on average only 1/4 of that in tank water over the year at a site with high concentrations of Pb in tank water. This is an indication that deposition from the atmosphere is not the major contributor to high lead concentrations in urban rainwater tanks in a city with reasonable air quality, though it is still a significant portion.

The PPARgamma agonist pioglitazone is effective in the MPTP mouse model of Parkinson's disease through inhibition of monoamine oxidase B

BACKGROUND AND PURPOSE

The peroxisome proliferator-activated receptor-gamma (PPARgamma) agonist pioglitazone has previously been shown to attenuate dopaminergic cell loss in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of Parkinson's disease, an effect attributed to its anti-inflammatory properties. In the present investigation, we provide evidence that pioglitazone is effective in the MPTP mouse model, not via an anti-inflammatory action, but through inhibition of MAO-B, the enzyme required to biotransform MPTP to its active neurotoxic metabolite 1-methyl-4-phenylpyridinium (MPP+).

EXPERIMENTAL APPROACH

Mice were treated with pioglitazone (20 mg kg(-1) b.i.d. (twice a day), p.o., for 7 days), prior and post or post-MPTP (30 mg kg(-1) s.c.) treatment. Mice were then assessed for motor impairments on a beam-walking apparatus and for reductions in TH immunoreactivity in the substantia nigra and depletions in striatal dopamine. The effects of pioglitazone on striatal MPP+ levels and MAO-B activity were also assessed.

KEY RESULTS

Mice treated with MPTP showed deficits in motor performance, marked depletions in striatal dopamine levels and a concomitant reduction in TH immunoreactivity in the substantia nigra. Pretreatment with pioglitazone completely prevented these effects of MPTP. However, pretreatment with pioglitazone also significantly inhibited the MPTP-induced production of striatal MPP+ and the activity of MAO-B in the striatum.

CONCLUSIONS AND IMPLICATIONS

The neuroprotection observed with pioglitazone pretreatment in the MPTP mouse model was due to the blockade of the conversion of MPTP to its active toxic metabolite MPP+, via inhibition of MAO-B.

DC-SIGN (CD209), pentraxin 3 and vitamin D receptor gene variants associate with pulmonary tuberculosis risk in West Africans

We investigated the role of DC-SIGN (CD209), long pentraxin 3 (PTX3) and vitamin D receptor (VDR) gene single nucleotide polymorphisms (SNPs) in susceptibility to pulmonary tuberculosis (TB) in 321 TB cases and 347 healthy controls from Guinea-Bissau. Five additional, functionally relevant SNPs within toll-like receptors (TLRs) 2, 4 and 9 were typed but found, when polymorphic, not to affect host vulnerability to pulmonary TB. We did not replicate an association between SNPs in the DC-SIGN promoter and TB. However, we found that two polymorphisms, one in DC-SIGN and one in VDR, were associated in a nonadditive model with disease risk when analyzed in combination with ethnicity (P=0.03 for DC-SIGN and P=0.003 for VDR). In addition, PTX3 haplotype frequencies significantly differed in cases compared to controls and a protective effect was found in association with a specific haplotype (OR 0.78, 95% CI 0.63-0.98). Our findings support previous data showing that VDR SNPs modulate the risk for TB in West Africans and suggest that variation within DC-SIGN and PTX3 also affect the disease outcome.

Characteristics of focused soft X-ray free-electron laser beam determined by ablation of organic molecular solids

A linear accelerator based source of coherent radiation, FLASH (Free-electron LASer in Hamburg) provides ultra-intense femtosecond radiation pulses at wavelengths from the extreme ultraviolet (XUV; lambda<100nm) to the soft X-ray (SXR; lambda<30nm) spectral regions. 25-fs pulses of 32-nm FLASH radiation were used to determine the ablation parameters of PMMA - poly (methyl methacrylate). Under these irradiation conditions the attenuation length and ablation threshold were found to be (56.9+/-7.5) nm and approximately 2 mJ*cm(-2), respectively. For a second wavelength of 21.7 nm, the PMMA ablation was utilized to image the transverse intensity distribution within the focused beam at mum resolution by a method developed here.

Characterisation of large-conductance calcium-activated potassium channels (BK(Ca)) in human NT2-N cells

Large-conductance calcium-activated potassium (BK(Ca)) channels were studied in inside-out patches of human NTERA2 neuronal cells (NT2-N). In symmetrical (140 mM) K(+) the channel mean conductance was 265 pS, the current reversing at approximately 0 mV. It was selective (P(K)/P(Na)=20:1) and blocked by internal paxilline and TEA. The open probability-voltage relationship for BK(Ca) was fitted with a Boltzmann function, the V((1/2)) being 76.3 mV, 33.6 mV and -14.1 mV at 0.1 muM, 3.3 muM and 10 muM [Ca(2+)](i), respectively. The relationship between open probability and [Ca(2+)](i) was fitted by the Hill equation (Hill coefficient 2.7, half maximal activation at 2.0 muM [Ca(2+)](i)). Open and closed dwell time histograms were fitted by the sum of two and three voltage-dependent exponentials, respectively. Increasing [Ca(2+)](i) produced both an increase in the longer open time constant and a decrease in the longest closed time constant, so increasing mean open time. "Intracellular" ATP evoked a concentration-dependent increase in NT2-N BK(Ca) activity. At +40 mV half-maximum activation occurred at an [ATP](i) of 3 mM (30 nM [Ca(2+)](i)). ADP and GTP were less potent, and AMP-PNP was inactive. This is the first characterisation of a potassium channel in NT2-N cells showing that it is similar to the BK(Ca) channel of other preparations.

Subthalamic nucleus neurones in slices from 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-lesioned mice show irregular, dopamine-reversible firing pattern changes, but without synchronous activity

The loss of dopamine in idiopathic or animal models of Parkinson's disease induces synchronized low-frequency oscillatory burst-firing in subthalamic nucleus neurones. We sought to establish whether these firing patterns observed in vivo were preserved in slices taken from dopamine-depleted animals, thus establishing a role for the isolated subthalamic-globus pallidus complex in generating the pathological activity. Mice treated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) showed significant reductions of over 90% in levels of dopamine as measured in striatum by high pressure liquid chromatography. Likewise, significant reductions in tyrosine hydroxylase immunostaining within the striatum (>90%) and tyrosine hydroxylase positive cell numbers (65%) in substantia nigra were observed. Compared with slices from intact mice, neurones in slices from MPTP-lesioned mice fired significantly more slowly (mean rate of 4.2 Hz, cf. 7.2 Hz in control) and more irregularly (mean coefficient of variation of inter-spike interval of 94.4%, cf. 37.9% in control). Application of ionotropic glutamate receptor antagonists 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) and 2-amino-5-phosphonopentanoic acid (AP5) and the GABA(A) receptor antagonist picrotoxin caused no change in firing pattern. Bath application of dopamine significantly increased cell firing rate and regularized the pattern of activity in cells from slices from both MPTP-treated and control animals. Although the absolute change was more modest in control slices, the maximum dopamine effect in the two groups was comparable. Indeed, when taking into account the basal firing rate, no differences in the sensitivity to dopamine were observed between these two cohorts. Furthermore, pairs of subthalamic nucleus cells showed no correlated activity in slices from either control (21 pairs) or MPTP-treated animals (20 pairs). These results indicate that the isolated but interconnected subthalamic-globus pallidus network is not itself sufficient to generate the aberrant firing patterns in dopamine-depleted animals. More likely, inputs from other regions, such as the cortex, are needed to generate pathological oscillatory activity.

Role of protein kinase C in modulation of excitability of CA1 pyramidal neurons in the rat

Biochemical and in situ hybridization studies demonstrated that the levels of protein kinase C variants were significantly increased in the hippocampus of the experimental models of epilepsy in rats. In addition it has been demonstrated that protein kinase C plays an important role in modulating synaptic transmission in the hippocampus. We examined the effects of activating of protein kinase C on the excitability of CA1 pyramidal neurons and synaptic transmission, using whole-cell current-clamp and extracellular field potential recording techniques. Indolactam V (1 microM) a novel protein kinase C activator, increased the excitability of CA1 neurons acting at both pre- and post-synaptic sites. Indolactam V, acting postsynaptically, significantly reduced the threshold for initiation of action potential from -42+/-3.8 mV to -51+/-3.1 mV and selectively inhibited the slow afterhyperpolarizing potential. Indolactam V also altered the neuronal firing properties in response to prolonged depolarizing pulse by eliminating the spike frequency accommodation. Our data indicate that indolactam V potentiated both amplitudes of Shaffer-collateral stimulation evoked excitatory postsynaptic currents and disynaptically evoked inhibitory evoked postsynaptic currents. However, the potentiation of inhibitory evoked postsynaptic currents amplitudes was not observed after blockade of NMDA and AMPA/kainate currents suggesting it was due to excitatory activity driving inhibitory neurons. The results indicate that the potentiation of pharmacologically isolated excitatory postsynaptic currents (215% of control) and amplitudes of population spikes (290% of control) was due to action of indolactam V presynaptically since the agonist reduced the paired-pulse ratio and the potentiating effect was not blocked by dialyzing the postsynaptic neuron through the recording electrode with a specific protein kinase C inactivator calphostin C. These findings suggest that protein kinase C increases the amplitude of epileptiform activity by causing potentiation of excitatory synaptic transmission, increasing the excitability of postsynaptic neurons and reducing negative feed back provided by slow afterhyperpolarizing potential.

Population genetic structure of a colonising, triploid weed, Hieracium lepidulum

Understanding the breeding system and population genetic structure of invasive weed species is important for biocontrol, and contributes to our understanding of the evolutionary processes associated with invasions. Hieracium lepidulum is an invasive weed in New Zealand, colonising a diverse range of habitats including native Nothofagus forest, pine plantations, scrubland and tussock grassland. It is competing with native subalpine and alpine grassland and herbfield vegetation. H. lepidulum is a triploid, diplosporous apomict, so theoretically all seed is clonal, and there is limited potential for the creation of variation through recombination. We used intersimple sequence repeats (ISSRs) to determine the population genetic structure of New Zealand populations of H. lepidulum. ISSR analysis of five populations from two regions in the South Island demonstrated high intrapopulation genotypic diversity, and high interpopulation genetic structuring; PhiST = 0.54 over all five populations. No private alleles were found in any of the five populations, and allelic differentiation was correlated to geographic distance. Cladistic compatibility analysis indicated that both recombination and mutation were important in the creation of genotypic diversity. Our data will contribute to any biocontrol program developed for H. lepidulum. It will also be a baseline data set for future comparisons of genetic structure during the course of H. lepidulum invasions.

Phasing diffuse scattering. Application of the SIR2002 algorithm to the non-crystallographic phase problem

A new phasing algorithm has been used to determine the phases of diffuse elastic X-ray scattering from a non-periodic array of gold balls of 50 nm diameter. Two-dimensional real-space images, showing the charge-density distribution of the balls, have been reconstructed at 50 nm resolution from transmission diffraction patterns recorded at 550 eV energy. The reconstructed image fits well with a scanning-electron-microscope (SEM) image of the same sample. The algorithm, which uses only the density modification portion of the SIR2002 program, is compared with the results obtained via the Gerchberg-Saxton-Fienup HiO algorithm. The new algorithm requires no knowledge of the object's boundary and proceeds from low to high resolution. In this way, the relationship between density modification in crystallography and the HiO algorithm used in signal and image processing is elucidated.

Coherent X-ray diffractive imaging: applications and limitations

The inversion of a diffraction pattern offers aberration-free diffraction-limited 3D images without the resolution and depth-of-field limitations of lens-based tomographic systems, the only limitation being radiation damage. We review our experimental results, discuss the fundamental limits of this technique and future plans.

An assessment of mosquito breeding and control in four surface flow wetlands in tropical-subtropical Australia

In Queensland, Australia, the tropical-subtropical climate is ideal to promote macrophyte growth in surface flow wetlands; however, there have been concerns that constructed wetlands are potential breeding sites for disease-bearing mosquitoes. The aim of this study was to assess whether mosquitoes were breeding in these constructed wetlands, and if so, where they breed, and what parameters might influence breeding: e.g. water quality, vegetation, or macroinvertebrate communities. A study of four surface flow constructed wetlands located in different climatic regions was undertaken. Mosquito larvae were sampled using 240 ml dippers and macroinvertebrates using dip nets. The wetland with the greatest biodiversity of macrophytes and macroinvertebrates had the least number of mosquito larvae (< 1% of all dips). Samples with most mosquito larvae occurred amongst dense mats of Paspalum grass or dead Typha. Despite the presence of larvae in some parts of these wetlands very few late instars or pupae were found i.e. completion of the mosquito life cycle to adult mosquitoes was unsuccessful. This study has shown that the presence of mosquito larvae can be minimised by increasing macroinvertebrate biodiversity, by planting a variety of macrophyte types and species, excluding aggressive plant species, and maintaining at least 30% open water. Macroinvertebrates are probably a crucial factor in the control of mosquito larvae ensuring that predation of the early instars prevents or limits the development of pupae and the emergence of adults.

Removal of endocrine disruptors by tertiary treatments and constructed wetlands in subtropical Australia

The controversial topic of endocrine disrupting chemicals (EDC) in aquatic environments is of international and Australian significance with the need for sustainable management of water resources increasing. The issues have been highlighted on the major continents of Europe and North America but so far have received less attention in Australia. A major source of these compounds has been identified as sewage effluent, which is treated prior to release to the environment with a primary focus on pathogen and nutrient removal. Sewage effluent is a complex mixture, which can contain many organic and inorganic compounds some of which may remain after treatment processes. More recently, technologies such as ozonation, UV treatment and advanced filtration have improved the quality of effluent discharged to the environment but there are still unresolved issues relating to poorly understood chemistries relating to EDCs in effluent discharges and the possible impacts in aquatic environments and to human health. This paper reports on an investigation of the removal from sewage effluent of selected chemicals that are known or suspected environmental endocrine disruptors (EEDs) by sand filtration, ozonation and UV treatment at the Landeborough Water Reclamation Plant in Queensland, Australia. Compounds detected in the raw effluent included pesticides, herbicides, some heavy metals and the human hormones 17beta estradiol and estrone. Most of these ware removed by the advanced treatments at the water reclamation plant, with only trace concentrations of some compounds present in the final effluent. Removal of toxicants by a free water surface wetland is also reported on. Some of the constraints of direct chemical measurements are discussed and some solutions proposed.

Evaluating student learning: an Australian case study

Determining the quality of student learning is an ongoing challenge to all educators. However, for educators and students in the health professions, evaluation of learning takes on a different dimension in terms of ensuring that graduates are competent, and thus safe, practitioners. This paper outlines the processes and methods by which student learning has been evaluated throughout a 22-year period at a large school of nursing in a Australian university. First, a historical overview of the major methods used demonstrates how relevant educational theories and sociopolitical forces and movements have influenced the whole curriculum including evaluation methods. Second, examples of current evaluation methods for undergraduate clinical and theoretical units are described. Reflections about past successes and future challenges conclude the paper.

Differential regulation of adipocytokine mRNAs by rosiglitazone in db/db mice

The precise mechanism by which PPARgamma activation by thiazolidinediones (TZDs) improves insulin sensitivity is still unclear. Recent studies have focused on the role of adipocytokines in metabolic control and their regulation by TZDs. In this study, we compared the chronic effects of antihyperglycemic doses of the TZD rosiglitazone, the beta3-adrenoceptor agonist BRL-35135, and the PPARalpha agonist Wy-14,643 on the mRNA expression of adipocytokines in WAT of db/db mice. Rosiglitazone treatment decreased adiponectin and resistin mRNA levels by 57 and 72%, respectively (P < 0.001), with no effect on the level of TNFalpha or RELMalpha transcripts. In comparison, Wy-14,643 reduced adiponectin transcript levels by 31% (P = 0.015) while BRL-35135 increased RELMalpha mRNA expression by 245% (P < 0.001) without effect on the other transcripts. Our results indicate that although a reduction in adiponectin and resistin mRNA levels in WAT by rosiglitazone treatment of diabetic mice may contribute to the antidiabetic effects, an alteration in TNFalpha, adiponectin, resistin, or RELMalpha mRNA expression is not absolutely required for the regulation of blood glucose concentration in the db/db mouse.

An efficient process for the synthesis of cyclic HPMPC

1-[((S)-2-Hydroxy-2-oxo-1,4,2-dioxaphosphorinan-5-yl)methyl] cytosine (cyclic HPMPC) was readily synthesized in gram to multi-kilogram quantities by treating a DMF suspension of HPMPC with four molar equivalents of ethyl chloroformate. This dehydrative intramolecular cyclization process typically afforded cHPMPC in 94% isolated yield and high purity. Benign by-products and solvents were easily removed.

Practical synthesis, separation, and stereochemical assignment of the PMPA pro-drug GS-7340

The practical synthesis of a mixed phenoxy-amidate derivative of PMPA with high oral bioavailability and favorable pharmacokinetics is described. The non-stereoselective synthetic route produces a 1:1 mixture of two diastereomers at phosphorous. Simulated moving bed chromatography using Chiralpak AS enabled kilo-scale isolation of the more potent diastereomer (GS-7340). The GS-7340 phosphorous chiral center was found to be (S) by X-ray crystallography.

Purification of PMPA amidate prodrugs by SMB chromatography and x-ray crystallography of the diastereomerically pure GS-7340

The diastereomers of GS-7171, aryl phosphoramidate derivatives of the anti-HIV nucleotide analog 9-[2-R-(phosphonomethoxy)propyl]adenine (tenofovir, PMPA), were isolated by batch elution chromatography and continuous simulated moving bed chromatography. The absolute configuration of the more pharmacologically active diastereomer, GS-7340, was determined to be (R,S,S) by single crystal x-ray crystallography.

A founder mutation of the potassium channel KCNQ1 in long QT syndrome: implications for estimation of disease prevalence and molecular diagnostics

OBJECTIVES

We took advantage of the genetic isolate of Finns to characterize a common long QT syndrome (LQTS) mutation, and to estimate the prevalence of LQTS.

BACKGROUND

The LQTS is caused by mutations in different ion channel genes, which vary in their molecular nature from family to family.

METHODS

The potassium channel gene KCNQ1 was sequenced in two unrelated Finnish patients with Jervell and Lange-Nielsen syndrome (JLNS), followed by genotyping of 114 LQTS probands and their available family members. The functional properties of the mutation were studied using a whole-cell patch-damp technique.

RESULTS

We identified a novel missense mutation (G589D or KCNQ1-Fin) in the C-terminus of the KCNQ1 subunit. The voltage threshold of activation for the KCNQ1-Fin channel was markedly increased compared to the wild-type channel. This mutation was present in homozygous form in two siblings with JLNS, and in heterozygous form in 34 of 114 probands with Romano-Ward syndrome (RWS) and 282 family members. The mean (+/- SD) rate-corrected QT intervals of the heterozygous subjects (n = 316) and noncarriers (n = 423) were 460 +/- 40 ms and 410 +/- 20 ms (p < 0.001), respectively.

CONCLUSIONS

A single missense mutation of the KCNQ1 gene accounts for 30% of Finnish cases with LQTS, and it may be associated with both the RWS and JLNS phenotypes of the syndrome. The relative enrichment of this mutation most likely represents a founder gene effect. These circumstances provide an excellent opportunity to examine how genetic and nongenetic factors modify the LQTS phenotype.

A selective orexin-1 receptor antagonist reduces food consumption in male and female rats

A variety of evidence implicates the orexins, especially orexin-A, in the regulation of food intake, but it has not been established whether this effect is mediated by the orexin-1 or orexin-2 receptor. In the present study, a selective orexin-1 receptor antagonist, 1-(2-methylbenzoxazol-6-yl)-3-[1,5]naphthyridin-4-yl urea hydrochloride (SB-334867-A), was administered intraperitoneally to rats under various conditions, and food consumption was subsequently measured over 24 h. In male rats, a single dose of SB-334867-A (30 mg/kg, i.p.) given during the light phase reduced both orexin-A-induced food intake (7 nmol, i.c.v.) and feeding stimulated by an overnight fast for 4 h. When given at the start of the dark phase, food consumption was reduced in both male and female rats over 24 h. Daily injections at the start of the dark phase for 3 days reduced natural feeding in male rats over 24 h on days one and three. These findings demonstrate direct inhibition of orexin-A induced food intake with a selective orexin-1 receptor antagonist. Furthermore, the suppression of nocturnal feeding and food intake stimulated by an overnight fast supports other evidence that orexin-A is involved in the regulation of natural feeding and suggests that orexin-1 receptor antagonists could be useful in the treatment of obesity.

Mice overexpressing human uncoupling protein-3 in skeletal muscle are hyperphagic and lean

Uncoupling protein-3 (UCP-3) is a recently identified member of the mitochondrial transporter superfamily that is expressed predominantly in skeletal muscle. However, its close relative UCP-1 is expressed exclusively in brown adipose tissue, a tissue whose main function is fat combustion and thermogenesis. Studies on the expression of UCP-3 in animals and humans in different physiological situations support a role for UCP-3 in energy balance and lipid metabolism. However, direct evidence for these roles is lacking. Here we describe the creation of transgenic mice that overexpress human UCP-3 in skeletal muscle. These mice are hyperphagic but weigh less than their wild-type littermates. Magnetic resonance imaging shows a striking reduction in adipose tissue mass. The mice also exhibit lower fasting plasma glucose and insulin levels and an increased glucose clearance rate. This provides evidence that skeletal muscle UCP-3 has the potential to influence metabolic rate and glucose homeostasis in the whole animal.