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Biomedical subjects

P Franck

Publications and source records attributed to P Franck.

At least 19 recordsLinked to original sources
PubMed2005

Anaphylactic reaction to inulin: first identification of specific IgEs to an inulin protein compound.

BACKGROUND: A woman with a past history of allergy to artichoke presented with two episodes of immediate allergic reactions, one of which was a severe anaphylactic shock after eating two types of health foods containing inulin. RESULTS: Dot blot assay techniques identified specific IgEs to artichoke, to yoghurt F, and to a heated BSA + inulin product. Dot blot inhibition techniques confirmed the anti-inulin specificity of specific IgE. CONCLUSIONS: The absence of a positive reaction to an unheated milk-inulin mixture indicates the probability of protein-inulin binding. There is no cross-reactivity with the carbohydrates of the glycosylated allergens.

Anaphylaxis↗
PubMed2005

Homocysteine and methylmalonic acid concentrations in cerebrospinal fluid: relation with age and Alzheimer's disease.

BACKGROUND: Homocysteine may be involved in the pathogenesis of late onset Alzheimer's disease. It is implicated in the metabolism of several important pathways in the brain. Methylmalonic acid (MMA) is related to the metabolism of branched chained amino acids and fatty acids. OBJECTIVES: To compare cerebrospinal fluid (CSF) total homocysteine and MMA in elderly subjects, patients with Alzheimer's disease, and younger healthy controls. SUBJECTS: CSF samples were obtained from 33 patients under 20 years of age; 28 patients aged 21 to 60 years; 22 normal elderly subjects aged over 60; and 38 Alzheimer patients aged over 60. RESULTS: CSF total homocysteine increased with age (mean (SD): 57 (35) nmol/l in the youngest group v 123 (89) nmol/l in the elderly group (p<0.001)). There was no difference between the elderly group and Alzheimer patients (115 (62) nmol/l). CSF MMA did not differ in the elderly group and the Alzheimer group (38 (13) v 35 (14) ng/ml). In the youngest group, it was significantly higher (60 (15) ng/ml). CONCLUSIONS: CSF total homocysteine is not increased in Alzheimer's disease compared with age matched controls. CSF total homocysteine was correlated with age. The decrease in CSF MMA levels with age eliminates a lack of vitamin B-12 at neuronal level.

Adult↗
PubMed2004

[Delayed diagnosis of homocystinuria by major deficiency in cystathionine beta synthase].

INTRODUCTION: Homocystinuria due to cystathionine beta synthase (CBS) deficiency is a special type of hyperhomocysteinemia because of its clinical expression (thrombotic events, ectopic lens and mental retardation). It's a rare, hereditary recessive autosomic disease generally diagnosed during childhood. EXEGESIS: Thrombophilia examination in a 50-year-old man found a dramatically increase homocysteinemia. Homocystinuria, profile of plasmatic amino acids and reduced CBS activity, (0.05 microkat/kg protein; N = 1.5 +/- 0.8) confirmed homocystinuria's diagnosis. Family study demonstrates that three siblings suffer from homocystinuria. Vitamin enriched diet with pyridoxin, vitamin B12 and folates induced reducing hyperhomocysteinemia and homocystinuria. CONCLUSION: This case report, original because of the diagnosis age, suggests a hyperhomocysteinemia's screening in patients with recurrent thrombotic events.

Cystathionine beta-Synthase↗
PubMed2004

Estimating admixture proportions with microsatellites: comparison of methods based on simulated data.

Several methods have been developed to estimate the parental contributions in the genetic pool of an admixed population. Some pair-comparisons have been performed on real data but, to date, no systematic comparison of a large number of methods has been attempted. In this study, we performed a simulated data-based comparison of six of the most cited methods in the literature of the last 20 years. Five of these methods use allele frequencies and differ in the statistical treatment of the data. The last one also considers the degree of molecular divergence by estimating the coalescence times. Comparisons are based on the frequency at which the method can be applied, the bias and the mean square error of the estimation, and the frequency at which the true value is within the confidence interval. Eventually, each method was applied to a real data set of variously introgressed honeybee populations. In optimal conditions (highly differentiated parental populations, recent hybridization event), all methods perform equally well. When conditions are not optimal, the methods perform differently, but no method is always better or worse than all others. Some guidelines are given for the choice of the method.

Animals↗
PubMed2004

Genetic structure of nest aggregations and drone congregations of the southeast Asian stingless bee Trigona collina.

In stingless bees, sex is determined by a single complementary sex-determining locus. This method of sex determination imposes a severe cost of inbreeding because an egg fertilized by sperm carrying the same sex allele as the egg results in a sterile diploid male. To explore how reproductive strategies may be used to avoid inbreeding in stingless bees, we studied the genetic structure of a population of 27 colonies and three drone congregations of Trigona collina in Chanthaburi, Thailand. The colonies were distributed across six nest aggregations, each aggregation located in the base of a different fig tree. Genetic analysis at eight microsatellite loci showed that colonies within aggregations were not related. Samples taken from three drone congregations showed that the males were drawn from a large number of colonies (estimated to be 132 different colonies in our largest swarm). No drone had a genotype indicating that it could have originated from the colony that it was directly outside. Combined, these results suggest that movements of drones and possibly movements of reproductive swarms among colony aggregations provide two mechanisms of inbreeding avoidance.

Animals↗
PubMed2004

Nest architecture and genetic differentiation in a species complex of Australian stingless bees.

We investigated the taxonomic significance of nest shape and its putative role in speciation in Trigona (Heterotrigona) carbonaria and T. (H.) hockingsi, two sibling species of stingless bee species from eastern Australia. These species are primarily distinguished by their nest architecture, as in all other respects they are nearly identical. We genotyped 130 colonies from six locations in Queensland at 13 microsatellite loci together with 106 additional colonies from six other Indo-Pacific Trigona species. Whether they were present in allopatry or in sympatry, colonies that displayed the T. carbonaria or the T. hockingsi nest architecture could be unambiguously differentiated at the genetic level. However, T. hockingsi colonies were classifiable into two highly differentiated paraphyletic and geographically separate populations, one in northern and one in southern Queensland. These two populations probably belong to two distinct species, T. hockingsi and T. davenporti nov. sp. Our results suggest that nest architecture characters are relevant but not sufficient criteria to identify species in this group. Consequently, modifications of nest architecture are probably not of prime importance in the speciation process of Australian stingless bees, although nest architecture differences probably result from relatively simple mechanisms. The rare interspecific hybrid colonies detected did not display a nest with an intermediate form between T. hockingsi and T. carbonaria.

Animals↗
PubMed2002

The allergenicity of soybean-based products is modified by food technologies.

BACKGROUND: Numerous products based on soybean are available and various food technologies are applied for their production. The allergenicity of natural soybean may be modified by these treatments. OBJECTIVES: To compare the allergenicity of native soybean proteins with those of soy milk and texturized protein products. To show additional allergens. METHODS: Three commercial products and two infant formulas were studied: Soybean flour, soy milk, texturized soy proteins, two infant formulas; the first containing total proteins and the second containing a soy protein hydrolysate. Sera from 9 patients allergic to soy protein were tested by immunoblotting (IB). IB inhibition was achieved by incubating sera with protein extract from soybean flour. RESULTS: The SDS-PAGE profile of soybean flour protein and soy milk showed a difference in the proportions of the various protein fractions, with a higher concentration of 37-kD protein in flour and 33-kD protein in milk. Infant formula 1 contained proteins with a molecular weight below 28 kD. The texturized extract contained high proportions of 31- to 34- and 38-kD proteins. Immunoblotting revealed a lack of allergenicity in infant formula. Sera recognizing the 38- and 50-kD proteins in texturized soy protein also recognized the 37- and 49-kD proteins in soybean flour and in soy milk, suggesting a protein glycation by texturization processes. The 30- to 34-kD band in texturized proteins was devoid of any allergenicity. This study seems to indicate that the 30-kD allergen (Gly m Bd 30) disappears during the production of texturized soy protein. CONCLUSION: All technologies applied to soybean-based products induce striking variation in the protein profile and allergenicity. Texturized protein could lack the major allergen Gly m Bd 30. Further studies or texturization might generate modified technologies in order to create hypoallergenic texturized proteins.

Adolescent↗
PubMed2001

Intracellular generation of free radicals and modifications of detoxifying enzymes in cultured neurons from the developing rat forebrain in response to transient hypoxia.

To address the influence of oxidative stress and defense capacities in the effects of transient hypoxia in the immature brain, the time course of reactive oxygen species generation was monitored by flow cytometry using dihydrorhodamine 123 and 2',7'-dichlorofluorescein-diacetate in cultured neurons issued from the fetal rat forebrain and subjected to hypoxia/reoxygenation (6 h/96 h). Parallel transcriptional and activity changes of superoxide dismutases, glutathione peroxidase and catalase were analyzed, in line with cell outcome. The study confirmed hypoxia-induced delayed apoptotic death, and depicted increased mitochondrial and cytosolic productions of free radicals (+30%) occurring over the 48-h period after the restoration of oxygen supply, with sequential stimulations of superoxide dismutases. Whereas catalase mRNA levels and activity were augmented by cell reoxygenation, glutathione peroxidase activity was transiently repressed (-24%), along with reduced glutathione reductase activity (-27%) and intracellular glutathione depletion (-19%). Coupled with the neuroprotective effects of the glutathione precursor N-acetyl-cysteine (50 microM), these data suggest that hypoxia/reoxygenation-induced production of reactive oxygen species can overwhelm glutathione-dependent antioxidant capacity, and thus may contribute to the resulting neuronal apoptosis.

Animals↗
PubMed2001

Genetic diversity of the honeybee in Africa: microsatellite and mitochondrial data.

A total of 738 colonies from 64 localities along the African continent have been analysed using the DraI RFLP of the COI-COII mitochondrial region. Mitochondrial DNA of African honeybees appears to be composed of three highly divergent lineages. The African lineage previously reported (named A) is present in almost all the localities except those from north-eastern Africa. In this area, two newly described lineages (called O and Y), putatively originating from the Near East, are observed in high proportion. This suggests an important differentiation of Ethiopian and Egyptian honeybees from those of other African areas. The A lineage is also present in high proportion in populations from the Iberian Peninsula and Sicily. Furthermore, eight populations from Morocco, Guinea, Malawi and South Africa have been assayed with six microsatellite loci and compared to a set of eight additional populations from Europe and the Middle East. The African populations display higher genetic variability than European populations at all microsatellite loci studied thus far. This suggests that African populations have larger effective sizes than European ones. According to their microsatellite allele frequencies, the eight African populations cluster together, but are divided in two subgroups. These are the populations from Morocco and those from the other African countries. The populations from southern Europe show very low levels of 'Africanization' at nuclear microsatellite loci. Because nuclear and mitochondrial DNA often display discordant patterns of differentiation in the honeybee, the use of both kinds of markers is preferable when assessing the phylogeography of Apis mellifera and to determine the taxonomic status of the subspecies.

Africa↗
PubMed2000

Free radical production and changes in superoxide dismutases associated with hypoxia/reoxygenation-induced apoptosis of embryonic rat forebrain neurons in culture.

Following hypoxia/reoxygenation (6h/96h), cultured neurons from the embryonic rat forebrain undergo delayed apoptosis. To evaluate the participation of oxidative stress and defense mechanisms, temporal evolution of intraneuronal free radical generation was monitored by flow cytometry using dihydrorhodamine 123, in parallel with the study of transcriptional, translational, and activity changes of the detoxifying enzymes Cu/Zn-SOD and Mn-SOD. Two distinct peaks of radical generation were depicted, at the time of reoxygenation (+ 27%) and 48 h later (+ 25%), respectively. Radical production was unaffected by caspase inhibitors YVAD-CHO or DEVD-CHO, which prevented neuronal damage, suggesting that caspase activation is not an upstream initiator of radicals in this model. Cell treatment by vitamin E (100 microM) displayed significant neuroprotection, whereas the superoxide generating system xanthine/xanthine oxidase induced apoptosis. Transcript and protein levels of both SODs were reduced 1 h after the onset of hypoxia, but activities were transiently stimulated. Reoxygenation was associated with an increased expression (139%), but a decreased activity (21%) of the inducible Mn-SOD, whereas Cu/Zn-SOD protein and activity were low and progressively increased until 48 h post-hypoxia, when the second rise in radicals occurred. In spite of a temporal regulation of SODs, which parallels radical formation, oxidative stress might account for neurotoxicity induced by hypoxia.

Aerobiosis↗
PubMed2000

Screening of new antioxidant molecules using flow cytometry.

We present a flow cytometry technique to evaluate the antioxidative properties of molecules on living cells, using a stable murine-murine hybridoma (Mark 3) cell line routinely cultured. Using this technique, intracellular superoxide anions and peroxides were evaluated with dihydrorhodamine (DHR-123) and dichlorofluorescein diacetate (DCFH-DA), respectively. When cells were first incubated for 10 min with either H(2)O(2) or the xanthine (X)/xanthine oxidase (XO) system, this flow cytometric technique was capable of evaluating the oxidative stress on cells. Twenty-one new analogues of ellipticine were synthesized and tested for their antioxidative properties compared to vitamin E and Ebselen used as references. A good statistical reflection of the antioxidative activities of these molecules was achieved by analyzing 35 000 cells in each experiment. Among them, the selenated molecule 18 was found to be 10 times more active than Ebselen but 10 000 times less active than vitamin E. Moreover, eight compounds showed glutathione peroxidase-like activities.

Animals↗
PubMed2000

Bovine beta-lactoglobulin receptors on transformed mammalian cells (hybridomas MARK-3): characterization by flow cytometry.

Flow cytometry was used to demonstrate the presence of beta-lactoglobulin (betaLG) receptors on living murine hybridoma MARK-3 cells using a fluorescein isothiocyanate-betaLG conjugate (FITC-betaLG: molar ratio of 5:1). A site occupation curve was produced using a shift in the mean channel fluorescence at various concentrations of FITC-betaLG. The binding of labelled ligand was concentration dependent and was inhibited by unlabelled betaLG. The on-rate constant was 3.2x10(2) M(-1) min(-1) and the off-rate constant was 0.002 min(-1). Scatchard plot analysis gave a dissociation constant (K(d)) of 44+/-21x10(-7) and 39+/-24x10(-5) M (n=3). Flow cytometry indicated that at least 15% of the FITC-betaLG were internalized for 5 min and that internalization was temperature- and time-dependent. The internalization was confirmed by 3-D fluorescence microscopy (CELLScan system).

Animals↗
PubMed2000

Lettuce allergy.

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Adult↗
PubMed2000

Hybrid origins of honeybees from italy (Apis mellifera ligustica) and sicily (A. m. sicula).

The genetic variability of honeybee populations Apis mellifera ligustica, in continental Italy, and of A. m. sicula, in Sicily, was investigated using nuclear (microsatellite) and mitochondrial markers. Six populations (236 individual bees) and 17 populations (664 colonies) were, respectively, analysed using eight microsatellite loci and DraI restriction fragment length polymorphism (RFLP) of the cytochrome oxidase I (COI)-cytochrome oxidase II (COII) region. Microsatellite loci globally confirmed the southeastern European heritage of both subspecies (evolutionary branch C). However, A. m. ligustica mitochondrial DNA (mtDNA) appeared to be a composite of the two European (M and C) lineages over most of the Italian peninsula, and only mitotypes from the African (A) lineage were found in A. m. sicula samples. This demonstrates a hybrid origin for both subspecies. For A. m. ligustica, the most widely exported subspecies, this hybrid origin has long been obscured by the fact that in the main area of queen production (from which most of the previous ligustica bee samples originated) the M mitochondrial lineage is absent, whereas it is present almost everywhere else in Italy. This presents a new view of the evolutionary history of European honeybees. For instance, the Iberian peninsula was considered as the unique refuge for the M branch during the quaternary ice periods. Our results show that the Apennine peninsula played a similar role. The differential distribution of nuclear and mitochondrial markers observed in Italy seems to be a general feature of introgressed honeybee populations. Presumably, it stems from the social nature of the species in which both genome compartments are differentially affected by the two (individual and colonial) reproduction levels.

Alleles↗
PubMed1999

Microsatellite analysis of sperm admixture in honeybee.

Sperm usage was investigated in an instrumentally inseminated honeybee queen. Her progeny were examined in the first 3 months of the egg-laying period using a microsatellite marker. Frequencies of different subfamilies differed significantly from one month to another. However, there was no evidence for sperm displacement or sperm precedence of a specific male in the worker progeny. The variance of subfamily proportions decreased over time suggesting that sperm admixture in the spermatheca was incomplete at the beginning of the egg-laying period of the queen and improved progressively during the first months after mating.

Animals↗
PubMed1998

Variation of microsatellite size homoplasy across electromorphs, loci, and populations in three invertebrate species.

Size homoplasy was analyzed at microsatellite loci by sequencing electromorphs, that is, variants of the same size (base pairs). This study was conducted using five interrupted and/or compound loci in three invertebrate species, the honey bee Apis mellifera, the bumble bee Bombus terrestris, and the freshwater snail Bulinus truncatus. The 15 electromorphs sequenced turned out to hide 31 alleles (i.e., variants identical in sequence). Variation in the amount of size homoplasy was detected among electromorphs and loci. From one to seven alleles were detected per electromorph, and one locus did not show any size homoplasy in both bee species. The amount of size homoplasy was related to the sequencing effort, since the number of alleles was correlated with the number of copies of electromorphs sequenced, but also with the molecular structure of the core sequence at each locus. Size homoplasy within populations was detected only three times, meaning that size homoplasy was detected mostly among populations. We analyzed population structure, estimating Fst and a genetic distance, based on either electromorphs or alleles. Whereas little difference was found in A. mellifera, uncovering size homoplasy led to a more marked population structure in B. terrestris and B. truncatus. We also showed in A. mellifera that the detection of size homoplasy may alter phylogenetic reconstructions.

Alleles↗
PubMed1998

Effects of H2O2 on the growth, secretion, and metabolism of hybridoma cells in culture.

The effect of low concentrations of hydrogen peroxide (H2O2) (5 x 10(-7)-9.5 x 10(-7) M) on cell growth and antibody production was investigated with murine hybridoma cells (Mark 3 and anti-hPL) in culture. Cell growth, measured by flow cytometry with morphological parameters, was significantly stimulated by H2O2 (8 x 10(-7) M) but H2O2 concentration of 7 x 10(-6) M and above increased cell death. H2O2 stimulation of antibody production was nonsignificant. The metabolism of cells treated with 8 x 10(-7) or 1 x 10(-5) M H2O2 was similar to that of the control in terms of glucose and glutamine consumption, lactate and ammonia production, and amino acid concentrations in the medium. The concentrations of lactate dehydrogenase, a marker of cell death, in test and control cells were similar. However, concentrations of intracellular free radicals measured by flow cytometry with dihydrorhodamine 123 (DHR 123) and dichlorofluorescein diacetate (DCFH-DA) as fluorochromes were different. The reactive oxygen species content of cells in 8 x 10(-7) M H2O2 was similar to that of the controls, but there was a sudden, marked production of superoxide anions (detected with DHR 123) and H2O2 or peroxides (detected with DCFH-DA) by cells incubated with 1 x 10(-5) M H2O2 which increased with increasing H2O2 until cell death.

Animals↗