The importance of HLA typing in cases of disputed paternity

In dispute paternity, the biologists must reply to two questions: 1. Is the paternity excluded or possible? 2. If it is possible, what is its probability? Valid answers can be given, using several genetic markers, among which HLA genes are specially interesting. Looking at HLA-A, B, C, DR typing of child, mother and presumed father, we propose a method which allows a direct calculation of paternity probability. Crossing over between HLA genes in presumed father and in mother are also considered in this method. In our experience, adding the date provided by the HLA genes and other genetic markers, we obtained, either formal exclusions, or possible paternities with a probability almost always higher than 90%.     

NMR local range investigations in amorphous starchy substrates I. Structural heterogeneity probed by (13)C CP-MAS NMR

The (13)C CP-MAS (Cross Polarization and Magic Angle Spinning) NMR signatures of a series of amorphous and semi-crystalline samples prepared from various starchy substrates (native potato starch, amylopectin, amylose) following different techniques of preparation (casting, freeze drying, solvent exchange) are compared. Decompositions of the C1 resonance spectra reveal the existence of four or five main types of alpha(1-4) linkages, which can be quantified. The influence of the intrinsic primary structure (linear or branched) and of the preparation procedure on conformational changes and resulting crystallinity are interpreted in terms of distributions of average glycosidic linkages dihedral angles (Phi, Psi). The role of hydration is also considered. An improved understanding at different structural levels is obtained in relation to local and intermediate range orders. Such information may be useful for the understanding of the structural evolution of a large variety of starchy substrates before or after treatments widely used in industrial processes.     

Modulation of cellulose nanocrystals amphiphilic properties to stabilize oil/water interface

Neutral cellulose nanocrystals dispersed in water were shown in a previous work to stabilize oil/water interfaces and produce Pickering emulsions with outstanding stability, whereas sulfated nanocrystals obtained from cotton did not show interfacial properties. To develop a better understanding of the stabilization mechanism, amphiphilic properties of the nanocrystals were modulated by tuning the surface charge density to investigate emulsifying capability on two sources of cellulose: cotton linters (CCN) and bacterial cellulose (BCN). This charge adjustment made it possible to determine the conditions where a low surface charge density, below 0.03 e/nm(2), remains compatible with emulsification, as well as when assisted by charge screening regardless of the source. This study discusses this ability to stabilize oil-in-water emulsions for cellulose nanocrystals varying in crystalline allomorph, morphology, and hydrolysis processes related to the amphiphilic character of nonhydrophobized cellulose nanocrystal.     

Effects of penitrem A on rat's performances in passive avoidance and Morris water maze tests

Intraperitoneal administration of the mycotoxin penitrem A 30 min before a training session in passive avoidance task, impaired performance of rats subjected to a test-session 24 h after. This effect was not antagonised by pretraining administration of physostigmine or bicuculline. Administration of penitrem A 20 min before a training session or 30 min before a test-session did not impair performance. In the Morris water maze, doses of penitrem A that induces slight to moderate tremors, but not a lower dose, disrupted place learning. These results suggest that penitrem A disrupts the processes that take place at the time of acquisition, but not those just after acquisition, and does not alter the restitution of information. This effect would not be related to a decrease of cholinergic neurotransmission nor to a stimulation of GABA A receptors. Nevertheless, it could not be totally excluded that the performance impairments induced by penitrem A would be secondary to a motor disruption. This revised version was published online in June 2006 with corrections to the Cover Date.     

Monitoring the crystallization of amylose–lipid complexes during maize starch melting by synchrotron x‐ray diffraction

Most starch granules exhibit a natural crystallinity, with different diffraction patterns according to their botanical origin: A‐type from cereals and B‐type from tubers. The V polymorph results essentially from the complexing of amylose with compounds such as iodine, alcohols, or lipids. The intensity and nature of phase transitions (annealing, melting, polymorphic transitions, recrystallization, etc.) induced by hydrothermal treatments in crystalline structures are related to temperature and water content. Despite its small concentration, the lipid phase present mainly in cereal starches has a large influence on starch properties, particularly in complexing amylose. The formation of Vh crystalline structures was observed by synchrotron x‐ray diffraction in native maize starch heated at intermediate and high moisture contents (between 19 and 80%). For the first time, the crystallization of amylose–lipid complexes was evidenced in situ by x‐ray diffraction without any preliminary cooling, at heating rates corresponding to the usual conditions for differential scanning calorimetry experiments. For higher water contents, the crystallization of Vh complexes clearly occurred at 110–115°C. For intermediate water contents, mixed A + Vh (or B + Vh for high amylose starch) diffraction diagrams were recorded. Two mechanisms can be involved in amylose complexing: the first relating to crystallization of the amylose and lipid released during starch gelatinization, and the second to crystalline packing of separate complexed amylose chains (amorphous complexes) present in native cereal starches. © 1999 John Wiley & Sons, Inc. Biopoly 50: 99–110, 1999     

Comparison of X-ray diffraction patterns and sorption properties of the hydrolyzed starches of potato, wrinkled and smooth pea, broad bean and wheat

The hydrolysis of native starches by hydrochloric acid (the so-called lintnerization process) yields a more crystalline material with moderately decreased water sorption capacities. X-ray diffraction may be used to rank native or lintnered starches from B to A type with intermediate type C mixtures and this change in order is parallelled by decreasing water affinities. The dependence of the intensity of the X-ray diffractogram on the water contents required for the A and B lattice spacings confirms the intimate rôle of water in the amylose crystalline structure.

Both structural and hydration hysteresis remain important in crystalline rich materials, suggesting that the mechanisms involved are not limited to long range interactions or mechanical tensions.     

Crystallinity and structuring role of water in native and recrystallized starches by C CP-MAS NMR spectroscopy: 1: Spectral decomposition

Amorphous, native, and recrystallized starches were studied by ¹³C CP-MAS NMR spectroscopy with respect to their behavior with hydration. The study of space groups, associated to crystalline polymorphs (B2 and P6₁ for A and B forms, respectively), provided decomposition rules for the spectral part due to crystalline phases. Moreover, the subtraction of a standard amorphous spectrum apparently showed the existence of three phases in native starches (amorphous, partially-ordered and crystalline) and only two in spherulitic crystals (partially-ordered and crystalline). The proportion of each phase was estimated at two different hydration levels. The amount of crystalline phase was compared to the degree of crystallinity as evaluated by wide angle X-ray scattering. The NMR spectral changes with hydration could be interpreted in terms of two complementary roles of water molecules, i.e. structuring and plasticizing.     

Characterization of PTZ-induced seizure susceptibility in a down syndrome mouse model that overexpresses CSTB

Down syndrome (DS) is a complex genetic syndrome characterized by intellectual disability, dysmorphism and variable additional physiological traits. Current research progress has begun to decipher the neural mechanisms underlying cognitive impairment, leading to new therapeutic perspectives. Pentylenetetrazol (PTZ) has recently been found to have positive effects on learning and memory capacities of a DS mouse model and is foreseen to treat DS patients. But PTZ is also known to be a convulsant drug at higher dose and DS persons are more prone to epileptic seizures than the general population. This raises concerns over what long-term effects of treatment might be in the DS population. The cause of increased propensity for epilepsy in the DS population and which Hsa21 gene(s) are implicated remain unknown. Among Hsa21 candidate genes in epilepsy, CSTB, coding for the cystein protease inhibitor cystatin B, is involved in progressive myoclonus epilepsy and ataxia in both mice and human. Thus we aim to evaluate the effect of an increase in Cstb gene dosage on spontaneous epileptic activity and susceptibility to PTZ-induced seizure. To this end we generated a new mouse model trisomic for Cstb by homologous recombination. We verified that increasing copy number of Cstb from Trisomy (Ts) to Tetrasomy (Tt) was driving overexpression of the gene in the brain, we checked transgenic animals for presence of locomotor activity and electroencephalogram (EEG) abnormalities characteristic of myoclonic epilepsy and we tested if those animals were prone to PTZ-induced seizure. Overall, the results of the analysis shows that an increase in Cstb does not induce any spontaneous epileptic activity and neither increase or decrease the propensity of Ts and Tt mice to myoclonic seizures suggesting that Ctsb dosage should not interfere with PTZ-treatment.