Brown rot and die-back disease induced by a cucurlionid (Lixus camerunus Klobe) in amaranth (Amaranthus hyhridus L.) in Nigeria

No abstract

Embryogenèse somatique chez le cotonnier (Gossypium hirsutum L.) : évolution des composés lipidiques au cours de la callogenèse et de la culture de suspensions cellulaires

L’implication des lipides dans le processus de l’embryogenèse somatique a été étudiée chez deux variétés de cotonnier (Gossypium hirsutum L.) : Coker 312, variété embryogène et ISA 205N, variété non embryogène. Le taux de lipides totaux de la variété ISA 205N est en général plus élevé que celui de la variété Coker 312. Ce taux atteint son optimum à la première subculture des cals et décroît par la suite régulièrement au cours de la culture de cellules. L’analyse qualitative des lipides montre que la composition lipidique des cals est identique chez les deux variétés. Cependant, on observe une accumulation de phospholipides sous forme de phosphocholine triacylglycérol (PTG) dans les suspensions cellulaires embryogènes de la variété Coker 312, contre une accumulation de galactolipides sous forme de digalactosyl diacylglycérol (DGDG) dans les suspensions cellulaires non embryogènes de la variété ISA 205N. Le PTG semble favoriser l’embryogenèse somatique tandis que le DGDG serait une cause de l’inhibition de l’embryogenèse somatique chez le cotonnier.Mots-clés : Gossypium hirsutum L., lipide, cal, suspension cellulaire, embryogenèse somatique

Vasodilatatie en beta-adrenerge blokkade bij de behandeling van hypertensiepatienten : klinische, haemodynamische en endocrinologische effecten met speciale aandacht voor de impedantietechniek

Verhoogde bloeddruk, gedefmieerd als een bloeddruk hoger dan 140/90 mm Hg, is een zeer frequent voorkomend verschijnsel. Ongeveer 20% van de volwassen Nederlandse bevolking heeft een te hoge bloeddruk. Uitgebreide Amerikaanse studies (o.a. de Framingham studie, de Veterans Adrninistration studie en de National Health Survey) tonen aan, dat in de leeftijdsgroep van 25 tot 34 jaar reeds 10 à 15% bij casual meting een bloeddruk hoger dan 160/95 mm Hg heeft. De omvang en de ernst van het hypertensieprobleem worden duidelijk wanneer men nagaat wat het effect van een verhoogde bloeddruk op de levensverwachting is. Met name de levensverzekerings- statistieken hebben duidelijk aangetoond, dat de overlevingsduur afneemt naarmate de bloeddruk hoger is. Dit geldt niet alleen voor een duidelijk verhoogde bloeddruk: een 45-jarige man met een bloeddruk ter grootte van 132/90 loopt reeds een significant hoger risico vergeleken met het standaard risico. Een verhoogde bloeddruk verkort de levensverwachting door het ontstaan van atherosclerose te bevorderen. Deze degeneratieve afwijking vormt momenteel de belangrijkste ziekte in de 'geciviliseerde' wereld. Roken en hyperlipidaernie bevorderen eveneens het proces van atherosclerose. Tesamen met hypertensie vormen zij de meest bekende risicofactoren. Uit tal van onderzoeken is duidelijk geworden, dat het terugdringen van deze risicofactoren de prognose aanzienlijk verbetert. Wanneer wij ons hier beperken tot het bloeddrukprobleem, dan blijkt antihypertensieve therapie met name bij de ernstiger vormen van hypertensie de levenskansen sterk te bevorderen. Het Veterans Administration onderzoek spreekt in dit opzicht duidelijke taal: bij mannen met een diastolische tensie van 115 à 130 mm Hg lag het aantal complicaties in de behandelde groep 35% lager dan in een placebogroep. Voor ernstige hypertensie lijkt het nut van behandeling wel vast te staan

Tunable variation of optical properties of polymer capped gold nanoparticles

Optical properties of polymer capped gold nanoparticles of various sizes (diameter 3-6 nm) have been studied. We present a new scheme to extract size dependent variation of total dielectric function of gold nanoparticles from measured UV-Vis absorption data. The new scheme can also be used, in principle, for other related systems as well. We show how quantum effect, surface atomic co - ordination and polymer - nanoparticle interface morphology leads to a systematic variation in inter band part of the dielectric function of gold nanoparticles, obtained from the analysis using our new scheme. Careful analysis enables identification of the possible changes to the electronic band structure in such nanoparticles.Comment: 13 pages,7 figures, 1 tabl

Standardisation of elemental analytical techniques applied to provenance studies of archaeological ceramics: an inter laboratory calibration study

Chemical analysis is a well-established procedure for the provenancing of archaeological ceramics. Various analytical techniques are routinely used and large amounts of data have been accumulated so far in data banks. However, in order to exchange results obtained by different laboratories, the respective analytical procedures need to be tested in terms of their inter-comparability. In this study, the schemes of analysis used in four laboratories that are involved in archaeological pottery studies on a routine basis were compared. The techniques investigated were neutron activation analysis (NAA), X-ray fluorescence analysis (XRF), inductively coupled plasma optical emission spectrometry (ICP-OES) and inductively coupled plasma mass spectrometry (ICP-MS). For this comparison series of measurements on different geological standard reference materials (SRM) were carried out and the results were statistically evaluated. An attempt was also made towards the establishment of calibration factors between pairs of analytical setups in order to smooth the systematic differences among the results

Effects of Cowpea mottle virus and Cucumber mosaic virus on six Soybean (Glycine max L.) cultivars

The study was carried out to determine the comparative pathogenic response of six cultivars of soybean; TGx 1844-18E, TGx 1448-2E, TGx 1910-8F, TGx 1019-2EN, TGx 1910-8F and TGx 1876-4E to single and mixed infections with cowpea mottle virus and cucumber mosaic virus. The experiment was conducted in the screenhouse at the crop production pavilion, Faculty of Agriculture, University of Ilorin, Ilorin, Kwara state Nigeria. The results of the experiment revealed that all soybean cultivars were susceptible to single and mixed infection of the two viruses but to seemingly different extent. The single infection with cowpea mottle virus (CMeV), however, caused the most severe symptoms on the soybean cultivars. Cucumber mosaic virus (CMV) alone was not as severe as the CMeV. The mixed infection of CMeV and CMV did not cause higher severity than CMeV alone indicating that there was little or no synergistic effect between the two viruses on soybean

Low thermal conductivity of the layered oxide (Na,Ca)Co_2O_4: Another example of a phonon glass and an electron crystal

The thermal conductivity of polycrystalline samples of (Na,Ca)Co_2O_4 is found to be unusually low, 20 mW/cmK at 280 K. On the assumption of the Wiedemann-Franz law, the lattice thermal conductivity is estimated to be 18 mW/cmK at 280 K, and it does not change appreciably with the substitution of Ca for Na. A quantitative analysis has revealed that the phonon mean free path is comparable with the lattice parameters, where the point-defect scattering plays an important role. Electronically the same samples show a metallic conduction down to 4.2 K, which strongly suggests that NaCo_2O_4 exhibits a glass-like poor thermal conduction together with a metal-like good electrical conduction. The present study further suggests that a strongly correlated system with layered structure can act as a material of a phonon glass and an electron crystal.Comment: 5 pages 3 figures, to be published in Phys. Rev.

MC1R variants increased the risk of sporadic cutaneous melanoma in darker-pigmented Caucasians: A pooled-analysis from the M-SKIP project.

The MC1R gene is a key regulator of skin pigmentation. We aimed to evaluate the association between MC1R variants and the risk of sporadic cutaneous melanoma (CM) within the M-SKIP project, an international pooled-analysis on MC1R, skin cancer and phenotypic characteristics. Data included 5,160 cases and 12,119 controls from 17 studies. We calculated a summary odds ratio (SOR) for the association of each of the nine most studied MC1R variants and of variants combined with CM by using random-effects models. Stratified analysis by phenotypic characteristics were also performed. Melanoma risk increased with presence of any of the main MC1R variants: the SOR for each variant ranged from 1.47 (95%CI: 1.17\u20131.84) for V60L to 2.74 (1.53\u20134.89) for D84E. Carriers of any MC1R variant had a 66% higher risk of developing melanoma compared with wild-type subjects (SOR; 95%CI: 1.66; 1.41\u20131.96) and the risk attributable to MC1R variants was 28%. When taking into account phenotypic characteristics, we found that MC1R-associated melanoma risk increased only for darker-pigmented Caucasians: SOR (95%CI) was 3.14 (2.06\u20134.80) for subjects with no freckles, no red hair and skin Type III/IV. Our study documents the important role of all the main MC1R variants in sporadic CM and suggests that they have a direct effect on melanoma risk, independently on the phenotypic characteristics of carriers. This is of particular importance for assessing preventive strategies, which may be directed to darker-pigmented Caucasians with MC1R variants as well as to lightly pigmented, fair-skinned subjects

PITX2 Modulates Atrial Membrane Potential and the Antiarrhythmic Effects of Sodium-Channel Blockers.

BACKGROUND: Antiarrhythmic drugs are widely used to treat patients with atrial fibrillation (AF), but the mechanisms conveying their variable effectiveness are not known. Recent data suggested that paired like homeodomain-2 transcription factor (PITX2) might play an important role in regulating gene expression and electrical function of the adult left atrium (LA). OBJECTIVES: After determining LA PITX2 expression in AF patients requiring rhythm control therapy, the authors assessed the effects of Pitx2c on LA electrophysiology and the effect of antiarrhythmic drugs. METHODS: LA PITX2 messenger ribonucleic acid (mRNA) levels were measured in 95 patients undergoing thoracoscopic AF ablation. The effects of flecainide, a sodium (Na(+))-channel blocker, and d,l-sotalol, a potassium channel blocker, were studied in littermate mice with normal and reduced Pitx2c mRNA by electrophysiological study, optical mapping, and patch clamp studies. PITX2-dependent mechanisms of antiarrhythmic drug action were studied in human embryonic kidney (HEK) cells expressing human Na channels and by modeling human action potentials. RESULTS: Flecainide 1 μmol/l was more effective in suppressing atrial arrhythmias in atria with reduced Pitx2c mRNA levels (Pitx2c(+/-)). Resting membrane potential was more depolarized in Pitx2c(+/-) atria, and TWIK-related acid-sensitive K(+) channel 2 (TASK-2) gene and protein expression were decreased. This resulted in enhanced post-repolarization refractoriness and more effective Na-channel inhibition. Defined holding potentials eliminated differences in flecainide's effects between wild-type and Pitx2c(+/-) atrial cardiomyocytes. More positive holding potentials replicated the increased effectiveness of flecainide in blocking human Nav1.5 channels in HEK293 cells. Computer modeling reproduced an enhanced effectiveness of Na-channel block when resting membrane potential was slightly depolarized. CONCLUSIONS: PITX2 mRNA modulates atrial resting membrane potential and thereby alters the effectiveness of Na-channel blockers. PITX2 and ion channels regulating the resting membrane potential may provide novel targets for antiarrhythmic drug development and companion therapeutics in AF

Melanocortin-1 Receptor, Skin Cancer and Phenotypic Characteristics (M-SKIP) Project: Study Design and Methods for Pooling Results of Genetic Epidemiological Studies

Background: For complex diseases like cancer, pooled-analysis of individual data represents a powerful tool to investigate the joint contribution of genetic, phenotypic and environmental factors to the development of a disease. Pooled-analysis of epidemiological studies has many advantages over meta-analysis, and preliminary results may be obtained faster and with lower costs than with prospective consortia. Design and methods: Based on our experience with the study design of the Melanocortin-1 receptor (MC1R) gene, SKin cancer and Phenotypic characteristics (M-SKIP) project, we describe the most important steps in planning and conducting a pooled-analysis of genetic epidemiological studies. We then present the statistical analysis plan that we are going to apply, giving particular attention to methods of analysis recently proposed to account for between-study heterogeneity and to explore the joint contribution of genetic, phenotypic and environmental factors in the development of a disease. Within the M-SKIP project, data on 10,959 skin cancer cases and 14,785 controls from 31 international investigators were checked for quality and recoded for standardization. We first proposed to fit the aggregated data with random-effects logistic regression models. However, for the M-SKIP project, a two-stage analysis will be preferred to overcome the problem regarding the availability of different study covariates. The joint contribution of MC1R variants and phenotypic characteristics to skin cancer development will be studied via logic regression modeling. Discussion: Methodological guidelines to correctly design and conduct pooled-analyses are needed to facilitate application of such methods, thus providing a better summary of the actual findings on specific fields