Phonon energy gaps in the charged incommensurate planes of the spin-ladder Sr14Cu24O41 compound by Raman and infrared spectroscopy

The terahertz (THz) excitations in the quantum spin-ladder system Sr14Cu24O41 have been determined along the c axis using THz time-domain, Raman, and infrared spectroscopy. Low-frequency infrared and Raman active modes are observed above and below the charge-ordering temperature T(co) is approximately equal to 200 K over a narrow interval approximately equal to 1-2 meV approximately equal to 8-16 cm(-1)). A new infrared mode at approximately equal to 1 meV develops below approximately equal to 100 K. The temperature dependence of these modes shows that they are coupled to the charge- and spin-density-wave correlations in this system. These low-energy features are conjectured to originate in the gapped sliding motion of the chain and ladder subsystems, which are both incommensurate and charged.

Body mass interacts with fat quality to determine the postprandial lipoprotein response in healthy young adults

BACKGROUND AND AIMS

Postprandial lipemia predicts the evolution of cardiovascular disease. Obesity is associated with an increase in the magnitude of postprandial lipemia. Our objective was to evaluate the influence of body mass index (BMI) on the effects of acute ingestion of different types of fat on the postprandial lipemic response.

METHODS AND RESULTS

Twenty-one healthy men followed a 4-week baseline diet and then consumed three fat-loaded meals that included 1g fat/kg body wt (65%fat) according to a randomized crossover design. The compositions of the three meals were olive oil meal (22% saturated fatty acids (SFA), 38% monounsaturated fatty acids (MUFA), 4% polyunsaturated fatty acids (PUFA)); butter meal (35% SFA, 22% MUFA, 4% PUFA); walnuts meal (20% SFA, 24% MUFA, 16% PUFA, and 4% α-linolenic acid). Higher-weight (HW) subjects (BMI greater than the median 26.18 kg/m(2), n = 11) presented higher incremental area under the curve (iAUC) for triglycerides (TG), both in large- and small-TG rich lipoproteins (TRL) than lower-weight (LW) subjects (BMI<26.18 kg/m(2), n = 10) (p<0.05), and a similar trend for plasma TG (p = 0.084). Moreover, HW subjects presented higher concentrations for small TRL-cholesterol and small TRL-TG in different timepoints of the postprandial lipemia after the intake of enriched walnuts or butter meals compared with the olive oil-enriched meal (p < 0.05) No significant differences were observed between the three types of meals in the postprandial response of LW subjects.

CONCLUSION

HW subjects present a greater postprandial response than LW subjects, and they benefit from the consumption of monounsaturated fatty acids from olive oil, to lower their levels of TRL particles during the postprandial state.

Persistence of microbial and chemical pig manure markers as compared to faecal indicator bacteria survival in freshwater and seawater microcosms

Natural seawater and freshwater microcosms inoculated with pig manure were set up to determine the persistence of pig faecal microbial and chemical markers in these two types of surface water. The concentrations of Lactobacillus amylovorus, the Bacteroidales Pig-2-Bac 16S rRNA genetic marker, five stanols and the evolution of two ratios of stanols, R1 (coprostanol to the sum of coprostanol and 24-ethylcoprostanol) and R2 (sitostanol to coprostanol) were analyzed during two months along with the concentration of Faecal Indicator Bacteria (FIB). Pig manure was inoculated to unfiltered water microcosms incubated aerobically at 18 °C in the dark. The faecal contamination load represented by the concentrations of culturable Escherichia coli and/or enterococci remained for two months in the freshwater and seawater microcosms water column. These concentrations followed a biphasic decay pattern with a 97% reduction of the initial amount during a first rapid phase (<6 days) and a remaining proportion undergoing a slower or null second decline. The L. amylovorus marker and five stanols persisted as long as the indicators in both treatments. The Pig-2-Bac marker persisted 20 and 27 days in seawater and freshwater, respectively. The ratios R1 and R2 were in the range specific to pig manure until day 6 in both types of water. These results indicate that Pig-2-Bac, L. amylovorus and stanol ratios might be used in combination to complement FIB testing to determine the pig source of fecal pollution. However, stanol ratios are to be used when the time point of the discharge is known.

Increased levels of microparticles originating from endothelial cells, platelets and erythrocytes in subjects with metabolic syndrome: relationship with oxidative stress

BACKGROUND AND AIMS

The Metabolic Syndrome (MetS) is associated with increased cardiovascular risk. Circulating microparticles (MP) are involved in the pathogenesis of atherothrombotic disorders and are raised in individual with CVD. We measured their level and cellular origin in subjects with MetS and analyzed their associations with 1/anthropometric and biological parameters of MetS, 2/inflammation and oxidative stress markers.

METHODS AND RESULTS

Eighty-eight subjects with the MetS according to the NCEP-ATPIII definition were enrolled in a bicentric study and compared to 27 healthy controls. AnnexinV-positive MP (TMP), MP derived from platelets (PMP), erythrocytes (ErMP), endothelial cells (EMP), leukocytes (LMP) and granulocytes (PNMP) were determined by flow cytometry. MetS subjects had significantly higher counts/μl of TMP (730.6±49.7 vs 352.8±35.6), PMP (416.0±43.8 vs 250.5±23.5), ErMP (243.8±22.1 vs 73.6±19.6) and EMP (7.8±0.8 vs 4.0±1.0) compared with controls. LMP and PNMP were not statistically different between groups. Multivariate analysis demonstrated that each criterion for the MetS influenced the number of TMP. Waist girth was a significant determinant of PMP and EMP level and blood pressure was correlated with EMP level. Glycemia positively correlated with PMP level whereas dyslipidemia influenced EMP and ErMP levels. Interestingly, the oxidative stress markers, plasma glutathione peroxydase and urinary 8-iso-prostaglandin F(2) α, independently influenced TMP and PMP levels whereas inflammatory markers did not, irrespective of MP type.

CONCLUSION

Increased levels of TMP, PMP, ErMP and EMP are associated with individual metabolic abnormalities of MetS and oxidative stress. Whether MP assessment may represent a marker for risk stratification or a target for pharmacological intervention deserves further investigation.

The metabotropic glutamate receptor antagonist 2-methyl-6-(phenylethynyl) pyridine decreases striatal VGlut2 expression in association with an attenuation of L-DOPA-induced dyskinesias

The striatal glutamatergic hyperactivity is considered critical in the development of levodopa-induced dyskinesias (LID) in Parkinson's disease (PD). Pharmacological antagonism of the metabotropic glutamate receptors (mGluRs), in particular, the subtype mGluR5, can inhibit the expression of dyskinesia in both rodent and nonhuman primate models of PD. However, the exact mechanisms underlying the mGluR5 antagonism effects are not completely known. The vesicular glutamate transporters (VGluts) are localized in the synaptic vesicles of the striatal glutamatergic axonal terminals. The effects of mGluR5 antagonism modulating VGlut1 and VGlut2, as selective markers for the corticostriatal and thalamostriatal pathways, respectively, are still unknown. We investigated the effects of the mGluR5 antagonist, 2-methyl-6-(phenylethynyl) pyridine (MPEP) on the striatal expression of VGlut1 and VGlut2 in levodopa-treated hemiparkinsonian rats. Male Sprague-Dawley rats received a unilateral 6-hydroxydopamine (6-OHDA) administration in the nigrostriatal pathway. Rats were treated with: (a) levodopa (12 mg/kg/day with benserazide 15 mg/kg, ip) + vehicle; (b) MPEP (1.5 mg/kg/day, ip) + vehicle; (c) levodopa + MPEP, or (d) saline for 10 days. Levodopa treatment induced dyskinesias and did not modify the striatal expression of either VGlut1 or VGlut2. The administration of MPEP significantly attenuated LID and decreased the levels of VGlut2, but not the VGlut1, in the striatum ipsilateral to the lesion (P < 0.05). Our results suggest that the effects of MPEP on LID might be mediated by a modulating effect on VGlut 2 expression.

Macroscopic quantum coherence of the spin triplet in the spin-ladder compound Sr14Cu24O41

We report the direct observation by inelastic neutron scattering experiments of a spin triplet of magnetic excitations in the response associated with the ladders in the composite cuprate Sr14Cu24O41. This appears as a peak at q(Q1D)=π and energy Δ1=32.5  meV, and we conjecture that all the triplets making up this conspicuous peak have the same phase and therefore interpret it as the signature of the occurrence of quantum coherence along the ladder direction between entangled spin pairs. From the comparison with previous neutron and x-ray data, we conclude that the temperature evolution of this mode is driven by the crystallization of holes into a charge density wave in the ladder sublattice.

Salmonella detection in feces during broiler rearing and after live transport to the slaughterhouse

Eggs and poultry meat are a common source of human salmonellosis. Contamination of poultry or poultry meat may occur throughout the production chain. Nevertheless, in Spain, noncontaminated broiler meat may be sold for human consumption from 2011. The aims of this study were as follows: (i) assess Salmonella detection from feces samples during the rearing and (ii) assess the influence of live transport to the slaughterhouse on Salmonella detection. During this study, 65 flocks were sampled at weekly intervals from the first day of rearing until slaughter. Samples of feces were taken from the litter using 5 pairs of cellulose sock swabs attached to boots and applied over the length of the house. To assess Salmonella detection rates before and after live transport to the slaughterhouse, feces samples were collected. Before loading, feces with 5 pairs of cellulose sock swabs were taken as described above. After transport, 2 pooled feces samples were taken directly from the truck (200 to 300 g each). All samples were analyzed in accordance with ISO 6579:2002 (Annex D). Results showed that regardless of whether broiler flocks arrived at the farm already shedding the bacteria in feces or they were infected during rearing, both groups described the same detection pattern, with the highest detection in feces at 14th day of rearing (50.5 and 34.5%, respectively). Moreover, Salmonella Enteritidis was the most prevalent serotype isolated during rearing (66.7%), followed by Salmonella Virchow (13.7%), Salmonella Hadar (9.4%), and Salmonella Ohio (2.8%). On the other hand, before loading and after transport to the slaughterhouse, 15.4 and 41.2% of feces samples collected were determined positive, respectively. In addition, a change in the serotype pattern was also observed. Salmonella Enteritidis remains the most prevalent serotype isolated (54.5%). Salmonella Hadar doubled the excretion rates (39.3%), and Salmonella Virchow and Salmonella Ohio were not isolated after transport.

Effect of the additional noradrenergic neurodegeneration to 6-OHDA-lesioned rats in levodopa-induced dyskinesias and in cognitive disturbances

Parkinson's disease is a motor and cognitive disorder characterised by a progressive loss of the substantia nigra pars compacta (SNc) dopaminergic neurons as well as of the locus coeruleus (LC) noradrenergic neurons. It has been suggested that LC neurodegeneration might influence levodopa-induced motor disturbances and cognitive performance. We investigated the influence of dopaminergic and noradrenergic lesions on levodopa-induced dyskinesias and on working memory in rats. Two groups of animals were used: (1) rats with a dopaminergic lesion induced by a unilateral administration of the neurotoxin 6-hydroxydopamine (6-OHDA), and (2) rats with a combined lesion of the dopaminergic and noradrenergic systems induced by 6-OHDA and N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP-4), respectively. Dyskinesias were evaluated on days 1, 8, 15 and 22 of chronic levodopa treatment (6 mg/kg, twice at day, i.p.). Working memory was evaluated by a radial-arm maze (1) before lesions, (2) before levodopa administration and (3) after 22 days of levodopa treatment. Total, axial, limb and orofacial dyskinesias not differed significantly between both groups. Working memory tasks worsened in both lesioned groups reaching significance in terms of time of performance (P < 0.05). The number of repeated entries in the same arm (errors) was only significant in the double-lesioned group (P < 0.05). This behaviour was not different from the one observed after chronic levodopa treatment. These results suggest that levodopa-induced dyskinesias in the 6-OHDA-lesioned rats were not affected by the additional noradrenergic lesion, whereas this last condition was sufficient to worse the cognitive performance deficit produced by the dopaminergic lesion.

Collective magnetic excitations in the spin ladder Sr14Cu24O41 measured using high-resolution resonant inelastic x-ray scattering

We investigate magnetic excitations in the spin-ladder compound Sr_{14}Cu_{24}O_{41} using high-resolution Cu L_{3} edge resonant inelastic x-ray scattering (RIXS). Our findings demonstrate that RIXS couples to two-triplon collective excitations. In contrast to inelastic neutron scattering, the RIXS cross section changes only moderately over the entire Brillouin zone, revealing high sensitivity also at small momentum transfers, allowing determination of the two-triplon energy gap as 100 +/- 30 meV. Our results are backed by calculations within an effective Hubbard model for a finite-size cluster, and confirm that optical selection rules are obeyed for excitations from this spherically symmetric quantum spin-liquid ground state.

Superconducting and normal phases of FeSe single crystals at high pressure

We report on the synthesis of superconducting single crystals of FeSe and their characterization by x-ray diffraction, magnetization and resistivity. We have performed ac susceptibility measurements under high pressure in a hydrostatic liquid argon medium up to 14 GPa and we find that T(C) increases up to 33-36 K in all samples, but with slightly different pressure dependences on different samples. Above 12 GPa no traces of superconductivity are found in any sample. We have also performed a room temperature high pressure x-ray diffraction study up to 12 GPa on a powder sample, and we find that, between 8.5 and 12 GPa, the tetragonal PbO structure undergoes a structural transition to a hexagonal structure. This transition results in a volume decrease of about 16% and is accompanied by the appearance of an intermediate, probably orthorhombic, phase.

Local administration of sarizotan into the subthalamic nucleus attenuates levodopa-induced dyskinesias in 6-OHDA-lesioned rats

RATIONALE

Dyskinesia affects the majority of levodopa-treated parkinsonian patients within 5-10 years of treatment with levodopa. Clinical and preclinical observations suggest that an increase in serotoninergic transmission can contribute to the appearance of dyskinesias. It is thus conceivable that a modulation of synaptic dopamine (DA) levels induced by the inhibition of serotonin (5-HT) release, as a consequence of 5-HT(1A) agonists administration, might alleviate dyskinesias.

OBJECTIVE

Since 5-HT(1A) receptors are expressed in the subthalamic nucleus (STN), the aim of the present study was to assess the effect of the intrasubthalamic administration of sarizotan, a compound with full 5-HT(1A) agonist properties, on levodopa-induced dyskinesias in the 6-hydroxydopamine (6-OHDA) model of parkinsonism.

MATERIALS AND METHODS

Male Sprague-Dawley rats received a unilateral 6-OHDA administration in the nigrostriatal pathway. A test of apomorphine was performed to evaluate dopamine depletion. One week later, a cannula was implanted in the STN. Animals were treated with levodopa (6 mg/kg, i.p., twice at day) for 22 consecutive days. On day 23, several doses (1 ng, 10 ng, or 1 microg) of sarizotan were administered through the cannula to the STN. The higher doses of sarizotan effectively attenuated all levodopa-induced dyskinesias including axial, limb, and orolingual subtypes.

CONCLUSIONS

These results suggest that the STN is a target structure for the antidyskinetic action of sarizotan and indicate that drug-mediated modulation of STN activity may be an alternative option for the treatment of levodopa-induced dyskinesias in Parkinson's disease.