Electron Accumulation and Emergent Magnetism in LaMnO_{3}/SrTiO_{3} Heterostructures.

Emergent phenomena at polar-nonpolar oxide interfaces have been studied intensely in pursuit of next-generation oxide electronics and spintronics. Here we report the disentanglement of critical thicknesses for electron reconstruction and the emergence of ferromagnetism in polar-mismatched LaMnO_{3}/SrTiO_{3} (001) heterostructures. Using a combination of element-specific x-ray absorption spectroscopy and dichroism, and first-principles calculations, interfacial electron accumulation, and ferromagnetism have been observed within the polar, antiferromagnetic insulator LaMnO_{3}. Our results show that the critical thickness for the onset of electron accumulation is as thin as 2 unit cells (UC), significantly thinner than the observed critical thickness for ferromagnetism of 5 UC. The absence of ferromagnetism below 5 UC is likely induced by electron overaccumulation. In turn, by controlling the doping of the LaMnO_{3}, we are able to neutralize the excessive electrons from the polar mismatch in ultrathin LaMnO_{3} films and thus enable ferromagnetism in films as thin as 3 UC, extending the limits of our ability to synthesize and tailor emergent phenomena at interfaces and demonstrating manipulation of the electronic and magnetic structures of materials at the shortest length scales.

Novel chiral magnetic domain wall structure in Fe/Ni/Cu(001) films.

Using spin-polarized low energy electron microscopy, we discovered a new type of domain wall structure in perpendicularly magnetized Fe/Ni bilayers grown epitaxially on Cu(100). Specifically, we observed unexpected Néel-type walls with fixed chirality in the magnetic stripe phase. Furthermore, we find that the chirality of the domain walls is determined by the film growth order with the chirality being right handed in Fe/Ni bilayers and left handed in Ni/Fe bilayers, suggesting that the underlying mechanism is the Dzyaloshinskii-Moriya interaction at the film interfaces. Our observations may open a new route to control chiral spin structures using interfacial engineering in transition metal heterostructures.

Creation of skyrmions in van der Waals ferromagnet Fe3GeTe2 on (Co/Pd) n superlattice.

Magnetic skyrmions are topological spin textures, which usually exist in noncentrosymmetric materials where the crystal inversion symmetry breaking generates the so-called Dzyaloshinskii-Moriya interaction. This requirement unfortunately excludes many important magnetic material classes, including the recently found two-dimensional van der Waals (vdW) magnetic materials, which offer unprecedented opportunities for spintronic technology. Using photoemission electron microscopy and Lorentz transmission electron microscopy, we investigated and stabilized Néel-type magnetic skyrmion in vdW ferromagnetic Fe3GeTe2 on top of (Co/Pd) n in which the Fe3GeTe2 has a centrosymmetric crystal structure. We demonstrate that the magnetic coupling between the Fe3GeTe2 and the (Co/Pd) n could create skyrmions in Fe3GeTe2 without the need of an external magnetic field. Our results open exciting opportunities in spintronic research and the engineering of topologically protected nanoscale features by expanding the group of skyrmion host materials to include these previously unknown vdW magnets.

Tunable Magnetoelastic Effects in Voltage-Controlled Exchange-Coupled Composite Multiferroic Microstructures.

The magnetoelectric properties of exchange-coupled Ni/CoFeB-based composite multiferroic microstructures are investigated. The strength and sign of the magnetoelastic effect are found to be strongly correlated with the ratio between the thicknesses of two magnetostrictive materials. In cases where the thickness ratio deviates significantly from one, the magnetoelastic behavior of the multiferroic microstructures is dominated by the thicker layer, which contributes more strongly to the observed magnetoelastic effect. More symmetric structures with a thickness ratio equal to one show an emergent interfacial behavior which cannot be accounted for simply by summing up the magnetoelastic effects occurring in the two constituent layers. This aspect is clearly visible in the case of ultrathin bilayers, where the exchange coupling drastically affects the magnetic behavior of the Ni layer, making the Ni/CoFeB bilayer a promising next-generation synthetic magnetic system entirely. This study demonstrates the richness and high tunability of composite multiferroic systems based on coupled magnetic bilayers compared to their single magnetic layer counterparts. Furthermore, because of the compatibility of CoFeB with present magnetic tunnel junction-based spintronic technologies, the reported findings are expected to be of great interest for the development of ultralow-power magnetoelectric memory devices.

[Mitral valve repair for rheumatic valve disease in children in Senegal: a review of 100 cases]. / La plastie mitrale sur valve rhumatismale chez l'enfant au Sénégal: 100 observations.

Mitral valve repair is a better therapeutic alternative than valve replacement for rheumatic valve disease in children. Repair procedures are especially well suited to developing countries where heart prostheses and life-long anti-coagulation therapy are largely unaffordable. The purpose of this study was to evaluate medium-term outcome of mitral valve repair in children in Senegal. A retrospective review was conducted in a cohort of 100 patients who underwent mitral valve repair for rheumatic mitral lesions over the 8-year period from 1999 to 2007. Mean age was 12 +/- 5 years (range, 7 to 17 years). The most common symptom of valve disease was dysypnea (stage IV in 26 cases and stage III in 74). Valve lesions were complex with anterior leaflet prolapse in 62 cases, posterior leaflet restriction in 35, commissural fusion in 30, and fusion of chordaes in 54. Repair procedures consisted of transfer and shortening of chordaes in 73 cases in association with commissurotomy in 22 cases and cleft closure in 17. Ring annuloplasty was performed in 84 patients. Hospital mortality was 2%. Postoperative morbidity was characterized by residual mitral regurgitation in four cases. Mean follow-up was 5 years. No late deaths were observed. Outcome was satisfactory in 84 patients with low-grade mitral regurgitation (grade I-II). Reduction of left ventricle diameter was statistically significant during systole and diastole, i.e., from 29.5 +/- 6.2 mm to 33.1 +/- 5.3 mm (p<0.05) and from 47.1 +/- 8.6 mm to 50.5 +/- 9.4 mm (p<0.05) respectively. Improvement in cardiac function was not significant, i.e., from 63.3 +/- 4.8% to 62 +/- 6.4% (p = 0.99). Mitral valve repair was successful in stabilizing myocardial function and remodeling the left ventricle. Outcome is dependent on careful patient selection and evaluation of lesions. Middle-term outcome is encouraging.

Anomalous orbital structure in two-dimensional titanium dichalcogenides.

Generally, lattice distortions play a key role in determining the electronic ground states of materials. Although it is well known that trigonal distortions are generic to most two dimensional transition metal dichalcogenides, the impact of this structural distortion on the electronic structure and topological properties has not been understood conclusively. Here, by using a combination of polarization dependent X-ray absorption spectroscopy (XAS), X-ray photoelectron spectroscopy (XPS) and atomic multiplet cluster calculations, we have investigated the electronic structure of titanium dichalcogenides TiX2 (X = S, Se, Te), where the magnitude of the trigonal distortion increase monotonically from S to Se and Te. Our results reveal the presence of an anomalously large crystal field splitting. This unusual kind of crystal field splitting is likely responsible for the unconventional electronic structure of TiX2 compounds and ultimately controls the degree of the electronic phase protection. Our findings also indicate the drawback of the distorted crystal field picture in explaining the observed electronic ground state and emphasize the key importance of trigonal symmetry, metal-ligand hybridization and electron-electron correlations in defining the electronic structures at the Fermi energy.

Coherent ac spin current transmission across an antiferromagnetic CoO insulator.

The recent discovery of spin current transmission through antiferromagnetic insulating materials opens up vast opportunities for fundamental physics and spintronics applications. The question currently surrounding this topic is: whether and how could THz antiferromagnetic magnons mediate a GHz spin current? This mismatch of frequencies becomes particularly critical for the case of coherent ac spin current, raising the fundamental question of whether a GHz ac spin current can ever keep its coherence inside an antiferromagnetic insulator and so drive the spin precession of another ferromagnet layer coherently? Utilizing element- and time-resolved x-ray pump-probe measurements on Py/Ag/CoO/Ag/Fe75Co25/MgO(001) heterostructures, here we demonstrate that a coherent GHz ac spin current pumped by the Py ferromagnetic resonance can transmit coherently across an antiferromagnetic CoO insulating layer to drive a coherent spin precession of the Fe75Co25 layer. Further measurement results favor thermal magnons rather than evanescent spin waves as the mediator of the coherent ac spin current in CoO.

Artificial two-dimensional polar metal at room temperature.

Polar metals, commonly defined by the coexistence of polar crystal structure and metallicity, are thought to be scarce because the long-range electrostatic fields favoring the polar structure are expected to be fully screened by the conduction electrons of a metal. Moreover, reducing from three to two dimensions, it remains an open question whether a polar metal can exist. Here we report on the realization of a room temperature two-dimensional polar metal of the B-site type in tri-color (tri-layer) superlattices BaTiO3/SrTiO3/LaTiO3. A combination of atomic resolution scanning transmission electron microscopy with electron energy-loss spectroscopy, optical second harmonic generation, electrical transport, and first-principles calculations have revealed the microscopic mechanisms of periodic electric polarization, charge distribution, and orbital symmetry. Our results provide a route to creating all-oxide artificial non-centrosymmetric quasi-two-dimensional metals with exotic quantum states including coexisting ferroelectric, ferromagnetic, and superconducting phases.

[Using PubMed subject headings to enhance reference searches]. / Utiliser les descripteurs dans PubMed pour améliorer une recherche bibliographique.

The PubMed search engine is an essential tool to stay abreast of the latest medical literature on specific topics. While the basic search techniques are common knowledge, the ability to use medical subject headings properly is an essential in obtaining valuable references. The purpose of this article is to explain what medical subject headings are and how they can be used to improve the results of reference searches in PubMed.

Quantitative Trait Loci Associated with Phenological Development, Low-Temperature Tolerance, Grain Quality, and Agronomic Characters in Wheat (Triticum aestivum L.).

Plants must respond to environmental cues and schedule their development in order to react to periods of abiotic stress and commit fully to growth and reproduction under favorable conditions. This study was initiated to identify SNP markers for characters expressed from the seedling stage to plant maturity in spring and winter wheat (Triticum aestivum L.) genotypes adapted to western Canada. Three doubled haploid populations with the winter cultivar 'Norstar' as a common parent were developed and genotyped with a 90K Illumina iSelect SNP assay and a 2,998.9 cM consensus map with 17,541 markers constructed. High heritability's reflected large differences among the parents and relatively low genotype by environment interactions for all characters considered. Significant QTL were detected for the 15 traits examined. However, different QTL for days to heading in controlled environments and the field provided a strong reminder that growth and development are being orchestrated by environmental cues and caution should be exercised when extrapolating conclusions from different experiments. A QTL on chromosome 6A for minimum final leaf number, which determines the rate of phenological development in the seedling stage, was closely linked to QTL for low-temperature tolerance, grain quality, and agronomic characters expressed up to the time of maturity. This suggests phenological development plays a critical role in programming subsequent outcomes for many traits. Transgressive segregation was observed for the lines in each population and QTL with additive effects were identified suggesting that genes for desirable traits could be stacked using Marker Assisted Selection. QTL were identified for characters that could be transferred between the largely isolated western Canadian spring and winter wheat gene pools demonstrating the opportunities offered by Marker Assisted Selection to act as bridges in the identification and transfer of useful genes among related genetic islands while minimizing the drag created by less desirable genes.

Unconventional magnetisation texture in graphene/cobalt hybrids.

Magnetic domain structure and spin-dependent reflectivity measurements on cobalt thin films intercalated at the graphene/Ir(111) interface are investigated using spin-polarised low-energy electron microscopy. We find that graphene-covered cobalt films have surprising magnetic properties. Vectorial imaging of magnetic domains reveals an unusually gradual thickness-dependent spin reorientation transition, in which magnetisation rotates from out-of-the-film plane to the in-plane direction by less than 10° per cobalt monolayer. During this transition, cobalt films have a meandering spin texture, characterised by a complex, three-dimensional, wavy magnetisation pattern. In addition, spectroscopy measurements suggest that the electronic band structure of the unoccupied states is essentially spin-independent already a few electron-Volts above the vacuum level. These properties strikingly differ from those of pristine cobalt films and could open new prospects in surface magnetism.

[Setting up a data collection and assessment system of the Permanent Healthcare Access Activities (PASS)]. / Mise en place d'un système de recueil et d'évaluation de l'activité médicosociale des permanences d'accès aux soins de santé (PASS).

INTRODUCTION: Five years after introducing the Permanent Access to Healthcare activity (PASS), it became necessary to analyse how it works. MATERIAL AND METHODS: A computerized data collection and assessment system intended to evaluate the PASS health activities has been set up in 11 University Hospitals and ten General Hospitals. From January 1st to June, 30th 2003 data was captured in a computer. RESULTS: The patients requiring medical advice are young (with an average age of 35 years) and present several signs of poverty in terms of accommodation, social relationships and financial means. Besides, almost all of them are uninsured. The PASS public corresponds completely to the created system. Poverty risk factors vary according to the geographic origin. Indeed, French people often suffer from isolation, whereas foreign patients present financial problems. The major part of patients are foreigners and more than a third of them do not speak French, which is an additional obstacle to care. Most of the time, the PASS patients present digestive disorders, nevertheless there are some differences between French and foreign patients. Indeed, foreigners very frequently have digestive and osteoarticluar problems, whereas French patients suffer from psychic disorders and present addictive behaviours. Some patients are sent to physicians downtown (9%) and to external medicosocial assistance centres (39.5%). DISCUSSION: This study (first one in France) provides us with homogenous data regarding the activities of PASS centres nationwide. The usefulness of computers and its acceptability facilitate data diffusion, with possibilities of adapting to each centre while preserving a common basis.

Imaging magnetic and ferroelectric domains and interfacial spins in magnetoelectric La0.7Sr0.3MnO3/PbZr0.2Ti0.8O3 heterostructures.

Strong magnetoelectric coupling can occur at the interface between ferromagnetic and ferroelectric films. Similar to work on interfacial exchange bias, photoemission electron microscopy was utilized to image both magnetic and ferroelectric domains and the resulting interfacial Ti spin in the same locations of La0.7Sr0.3MnO3/PbZr0.2Ti0.8O3 heterostructures. Multiple image analysis techniques, which could be applicable for a variety of fields needing quantitative data on image switching, confirm both improved magnetic switching and an increased population of interfacial spins with increased thickness of the ultrathin La0.7Sr0.3MnO3 layer. The perpendicular orientation of the interfacial spins is also discussed. This work suggests a magnetoelectric dead layer, with reduced interfacial magnetoelectricity when thin magnetic films are present.

Comparative study of the distribution of fuzzy coat, lectin receptors, and intramembrane particles of the ciliary membrane.

Cilia from seminal vesicles of Discoglossus (Anura, Amphibia) are partially covered with a fuzzy coat easily stained by the PATAg technique. The freeze-fractures of the ciliary membrane show large intramembrane particles (IMPs) not randomly distributed. At the base of the cilium, 3 or 4 rows of large IMPs form the ciliary necklace. Above the necklace, a 0.1 micrometer high region is devoid of particles after which the shaft membrane exhibits large IMPs coarsely lined up in 9 longitudinal rows 0.6 micrometer in height. Smaller IMPs appear randomly dispersed. The fuzzy coat is well developed in regions possessing large IMPs: the necklace region and the basal portion of the shaft. Between the necklace and the shaft, the region lacking in IMPs is also devoid of fuzzy coat. The distribution of Con A receptors is similar to that of large IMPs and to that of filaments in the fuzzy coat. On the contrary, wheat germ agglutinin (WGA) receptors are randomly distributed all along the ciliary membrane. Finally, the relationships between fuzzy coat, lectin receptors, IMPs and fibrillar links between plasma membrane and microtubules of the axoneme are illustrated.

Use of the multiple-day weighed record for Senegalese children during the weaning period: a case of the "instrument effect".

In West Africa, the multiple-day weighed record is the most widely used technique for measuring children's food intakes. The children's eating behavior might be disrupted by the frequent weighings and the presence of a field-worker in the home. We explored the possibility of such an "instrument effect" in a 7-d food survey of 70 Senegalese children aged 10-13 mo. Energy intakes decreased significantly during the food survey (P < 0.0001). The decrease affected both daytime breast milk intake (8%) and solid food intakes (15%). The children's weight gain also decreased from a presurvey value of 6.9 to 2.1 g.kg-1.wk-1, indicating that their intakes during the food survey were lower than their usual intakes. The food-survey methodology was responsible for this "instrument effect." Policy decision-makers should be aware that data collected with the multiple-day weighed record technique might not reflect African children's usual food intakes.

PIP: The multiple-day weighed record derived from Food and Agriculture Organization methodology is the most widely used technique in West Africa for measuring children's food intakes. Children's eating behavior may, however, be disrupted by the frequency of weighings and the presence of a field-worker in the home. The authors therefore explored the possibility of this instrument effect in a 7-consecutive-day food survey of 39 Senegalese boys and 31 Senegalese girls aged 10-13 months residing in Pikine, a suburb of Dakar. Analysis of variance with a repeated-measures design was used to test day-of-the-week, day-of-the-food survey, and week-of-study effects, while contrast analysis was used to compare particular days or weeks. The study found that energy intakes decreased significantly during the food survey. The overall decreases were 8% in the amount of daytime breast milk intake and 15% of solid food intake. Children's weight gain also decreased from a presurvey value of 6.9 to 2.1 grams per kilogram per week. The food survey methodology was responsible for the decrease relative to usual food intake. Policy decision makers should thus be aware of the potential of this effect when reviewing and employing data derived from the methodology.

Bradycardic responses to microinjection of N-methyl-D-aspartate into the nucleus tractus solitarius are inhibited by local activation of 5-HT(3) receptors.

Previous reports have described that glutamate ionotropic receptors in the nucleus tractus solitarius (NTS) are involved in the reflex control of heart rate, and that such a control can be inhibited by NTS-5-HT(3) receptor stimulation. In the present study, we examined in urethane anaesthetized rats the effects of intra-NTS microinjection of 1-(m-chlorophenyl)-biguanide (CPBG), a potent and selective 5-HT(3) receptor agonist, on the cardiovascular responses to local administration of glutamate ionotropic receptor agonists. Intra-NTS microinjection of CPBG reduced the atropine-sensitive bradycardia elicited by local microinjection of NMDA without affecting the cardiovascular responses to intra-NTS microinjections of AMPA or kainic acid. The reduction by CPBG of the NMDA-evoked cardiac response was blocked by prior intra-NTS microinjection of granisetron, a 5-HT(3) receptor antagonist, as well as bicuculline, a GABA(A) receptor antagonist. These results suggest that the stimulation of NTS 5-HT(3) receptors specifically reduces, via a GABA-dependent mechanism, the cardiac response to local NMDA administration.

The 24-hour recall for Senegalese weanlings: a validation exercise.

OBJECTIVE: In Africa, where growth retardation is highly prevalent, the use of expensive and time-consuming diet assessment techniques is a major obstacle to the collection of dietary data on large samples of children. The 24-h recall could be a valuable alternative. Its validity and reproducibility were assessed by comparison with the precise weighing technique. DESIGN & SUBJECTS: Intakes of complementary foods of 45 Senegalese weanlings, aged 11-18 months, were estimated with both techniques on the same days. RESULTS: There was neither a level-dependent nor a systematic bias with the 24-h recall for energy and macronutrient intakes. Mean differences between techniques were < 11% of mean intakes. Rank order correlations (r) ranged from 0.60 to 0.81 for energy and macronutrients. However, the analysis by food group showed that the 24-h recall was less precise than the reference, especially for foods from the household common pot (r ranged from 0.31 to 0.61 for rice, oil and fish). In particular, measuring rice intake as a number of 'handfuls' was not satisfactory. The technique needs further improvement for these foods. CONCLUSION: Since it provides unbiased estimates of weanlings' intakes, the 24-h recall can be used for diet surveys of groups of children. Its lack of precision, which could cause attenuation in epidemiological studies, can be compensated by increasing the number of days of survey. This study suggests that a precision equivalent to that of a 1-day weighed survey could be obtained with two 24-h recalls, at a considerably lower cost.

PIP: Growth retardation is highly prevalent in Africa. Given the limited available financial resources across most of the continent for the collection of dietary data on large samples of children, alternatives to expensive and time-consuming diet assessment techniques are called for. 24-hour recall may be one such alternative. The authors report their findings from an exploration of the validity and reproducibility of this approach compared to the precise weighing technique. The intakes of complementary foods were estimated for 45 Senegalese weanlings aged 11-18 months with both techniques on the same days. For each child, the study lasted four days spread over one day of qualitative observation, two days of precise weighing, and three days of 24-hour interviews. The study found the 24-hour recall approach to have neither a level-dependent nor systematic bias with regard to energy and macronutrient intakes. Mean differences between techniques were 11% of mean intakes. Analysis by food group found recall to be less precise than the reference, especially for food from the household common pot such as rice, oil, and fish. The authors conclude that the recall approach's ability to provide unbiased estimates of weanling's intakes makes it a viable assessment tool in diet surveys of groups of children. Its lack of precision can be compensated by increasing the number of days of the survey. Findings suggest that the precision of a one-day weighed survey could be obtained with two 24-hour recalls at considerably lower cost.

Ordinary and opportunistic enteropathogens associated with diarrhea in Senegalese adults in relation to human immunodeficiency virus serostatus.

OBJECTIVES: A survey was conducted in Dakar, Senegal, to identify major types and prevalences of bacteria, parasites, fungi, and Rotaviruses associated with diarrhea in relation to human immunodeficiency virus (HIV) serostatus with the goal to provide guidance to physicians for case management. METHODS: Etiologic agents were identified in a case control study: cases were HIV-infected patients with diarrhea (HIV+ D+) and HIV seronegative patients with diarrhea (HIV D+); controls were HIV-infected patients without diarrhea (HIV+ D ) and seronegative controls without diarrhea (HID D ). Ordinary enteric pathogens were identified by conventional methods. Different Escherichia coli pathotypes were characterized by polymerase chain reaction (PCR), identification of HEp-2 cell adherence pattern, Sereny test, GM1-ELISA, and the suckling mouse assay. Opportunistic parasites, such as Cryptosporidium and Microsporidium, were identified by the Kinyoun method and trichromic stain of Weber, respectively. Rotaviruses were identified with a commercial latex agglutination kit. Antimicrobial susceptibility testing was carried out by the disk diffusion method. RESULTS: Among the 594 patients examined, 158 were HIV+ D+, 121 were HIV2 D+, 160 were HIV+ D , and 155 were HIV D . The main etiologies of diarrhea were different according to HIV serostatus of patients. In immunocompetent adults the main causes of diarrhea were Shigella sp (12.4%), Entamoeba histolytica(10.7%), Salmonella enterica (6.6%), and Giardia (4.9%). In the immunocompromised host the more frequent pathogens were enteroaggregative E. coli (19.6%), Microsporidium (9.4%), Cryptosporidium sp (8.2%), Rotavirus (8.2%), Shigella sp (7.6%), Candida albicans (7.6%), E. histolytica (5.1%), S. enterica (4.4%), and Isospora belli (4.4%). Also, Blastocystis hominis has to be considered as an opportunistic parasite, because it was identified only in HIV-infected patients, with higher prevalence in adults with diarrhea (2.5% in HIV+ D+ patients; 0.6% in HIV+ D patients). High level of asymptomatic carriage of Ascaris lumbricoides and Trichuris trichiura and some cases of multiple infections were observed. Fungi, Cryptosporidium sp and Microsporidium sp, were often identified in patients with low CD4 counts (range, 79 250 cells/mL). Independently from HIV-serostatus, CD4 count was lower in diarrheic persons, suggesting that diarrhea is a debilitating illness and that effective management of diarrhea can prevent immunosuppression. Isolated enteropathogenic strains displayed high resistance to most antibiotics used in Senegal for treating diarrhea (ampicillin, tetracycline, cotrimoxazole); they were susceptible to amikacin, gentamicin, and norfloxacin. CONCLUSION: These epidemiologic data suggest that guidelines for the management of diarrhea during HIV infection in Dakar should be updated.

Stimulation of 5-HT2 receptors in the nucleus tractus solitarius enhances NMDA receptor-mediated reflex-evoked bradycardiac responses in the rat.

The modulation by 5-HT2 receptors in the nucleus tractus solitarius of the reflex bradycardia evoked by stimulation of peripheral baroreceptors and cardiopulmonary chemoreceptors, and their possible functional interactions with local NMDA receptors, were investigated in pentobarbital- and urethane-anaesthetized rats, respectively. Microinjection of the 5-HT2 receptor agonist, 2,5-dimethoxy-4-iodoamphetamine (0.1-0.5 pmol), into the nucleus tractus solitarius elicited a dose-dependent hypotension and bradycardia. Bilateral microinjections at the same site of a subthreshold dose of 2,5-dimethoxy-4-iodoamphetamine (0.05 pmol) significantly enhanced the aforementioned reflex-evoked bradycardiac responses. In contrast, local bilateral microinjections of the NMDA receptor antagonist, 2-amino-5-phosphonopentanoic acid (500 and 1000 pmol), reduced, in a dose-dependent manner, both reflex-evoked responses. The facilitatory effect of 2,5-dimethoxy-4-iodoamphetamine upon these reflex-evoked bradycardiac responses was prevented by prior local microinjection of low doses of either the selective 5-HT2 receptor antagonist, ketanserin (10 pmol), or 2-amino-5-phosphonopentanoic acid (100 pmol), which, on their own, did not affect the reflex-associated bradycardia. These data suggest that 5-HT2 receptors within the nucleus tractus solitarius participate in a facilitatory modulation of the reflex control of heart rate, probably through functional interactions with local NMDA receptors.

Comparative study of the lubricant performance of Compritol HD5 ATO and Compritol 888 ATO: effect of polyethylene glycol behenate on lubricant capacity.

The aim of this paper is to study the lubricant capacity of Compritol HD5 ATO, a glyceryl and polyethylene glycol dibehenate, obtained by atomization. This material is compared to Compritol 888 ATO, constituted only by glyceryl dibehenate. First, this study verifies that Compritol HD5 ATO and Compritol 888 ATO present the same granular characteristics and that their mixes with Lactopress present no structural differences. Secondly, in term of compressibility and cohesiveness, the use of Compritol 888 ATO or Compritol HD5 ATO with Lactopress does not involve any significant modification. Finally, the minor difference of lubricant capacity between Compritol HD5 ATO and Compritol 888 ATO has no consequence in compression practice. The presence of polyethylene glycol behenate does not decrease the glyceryl dibehenate compression functionality. This study concludes that Compritol HD5 ATO could be a very interesting excipient because it associates the glyceryl dibehenate lubricant capacity with the polyethylene glycol behenate-specific capacity in terms of dissolution enhancement.