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1.
Travel Med Infect Dis ; 60: 102727, 2024 May 19.
Article in English | MEDLINE | ID: mdl-38768905

ABSTRACT

OBJECTIVES: There is little data on pregnant women with imported malaria in high-income countries, especially regarding offspring outcomes. We wanted to determine pregnancy outcomes of imported malaria in pregnant women in mainland France. PATIENTS AND METHODS: We conducted a retrospective, descriptive study of outcomes in pregnant women hospitalized with malaria from 2004 to 2014 in two regions of mainland France. An adverse outcome was defined as a miscarriage, stillbirth, preterm birth (<35 weeks of gestation), low birth weight (LBW) defined as less than 2500 g, or congenital malaria. RESULTS: Of 60 pregnancies, 5 were excluded because of elective abortions; 55 were investigated, of which 11 were primigravidae and 44 multigravidae. Pregnancies were singleton (n = 51) or twin (n = 4). Mean age was 30.4 years (range:19-45 y). Among the 55 cases, 9 ended in a miscarriage (8 singletons and 1 twin pregnancy) and 1 had a stillbirth at 21 weeks of gestation, all immediately after the malarial episode. 45 gave birth (29 vaginal deliveries and 16 caesarean sections) to 48 (42 singletons and 6 twins) newborns. Amongst these, 30 were healthy full-term newborns, 10 had LBW, and 8 were preterm. Overall, 26 of 55 (47.3%) pregnancies, and 29 of 59 (49.2%) offsprings had adverse outcomes. Compared to singleton pregnancies, twin pregnancies were associated with adverse outcomes (p = 0.0438). CONCLUSIONS: Imported malaria has a severe impact on pregnancy outcomes. Prevention and management of imported malaria in pregnancy should be optimized.

3.
Med Mal Infect ; 50(2): 99-112, 2020 Mar.
Article in English | MEDLINE | ID: mdl-31257063

ABSTRACT

In 2015, 212 million new cases of malaria were reported, causing 429,000 deaths. The World Health Organization (WHO) estimated a 41% decrease in the number of new cases worldwide between 2000 and 2015. The number of deaths from malaria fell by 62% worldwide and by 71% in Africa. In mainland France, malaria is mainly imported by travelers or migrants from endemic areas, in particular sub-Saharan Africa (95%). In France, the number of imported malaria cases, mainly due to Plasmodium falciparum (85%), was estimated at about 82,000 for the period 2000-2015. Over the same period, 6,468 cases of malaria were reported in the French armed forces, of which 2,430 cases (37.6%) were considered as imported because occurring outside of endemic areas. The number of malaria cases also fell between 2000 and 2015 in Mayotte and French Guiana, a malaria transmission zone. Mayotte has entered the elimination of malaria with less than 15 cases per year. In French Guiana, between 300 and 500 cases have been reported annually in recent years. The decline in morbidity and mortality is usually attributed to vector control measures and improved access to effective treatments. However, the Anopheles mosquitoes that transmit the disease have developed resistance against most insecticides. Similarly, malaria parasites have developed resistance against most of the antimalarial drugs used as prevention or treatment, even the latest marketed combinations such as artemisinin-based combination therapies.


Subject(s)
Malaria/epidemiology , Animals , Communicable Diseases, Imported/epidemiology , France/epidemiology , Global Health , Humans , Incidence , Time Factors
4.
Med Mal Infect ; 50(2): 127-140, 2020 Mar.
Article in English | MEDLINE | ID: mdl-30885541

ABSTRACT

Since the 2007 French guidelines on imported Falciparum malaria, the epidemiology, treatment, and prevention of malaria have changed considerably requiring guidelines for all Plasmodium species to be updated. Over the past decade, the incidence of imported malaria has decreased in all age groups, reflecting the decrease in the incidence of malaria in endemic areas. The rates of severe pediatric cases have increased as in adults, but fatalities are rare. The parasitological diagnosis requires a thick blood smear (or a rapid immunochromatographic test) and a thin blood film. Alternatively, a rapid antigen detection test can be paired with a thin blood film. Thrombocytopenia in children presenting with fever is highly predictive of malaria following travel to a malaria-endemic area and, when detected, malaria should be strongly considered. The first-line treatment of uncomplicated P. falciparum malaria is now an artemisinin-based combination therapy (ACT), either artemether-lumefantrine or artenimol-piperaquine, as recommended by the World Health Organization in endemic areas. Uncomplicated presentations of non-falciparum malaria should be treated either with chloroquine or ACT. The first-line treatment of severe malaria is now intravenous artesunate which is more effective than quinine in endemic areas. Quinine is restricted to cases where artesunate is contraindicated or unavailable. Prevention of malaria in pediatric travelers consists of nocturnal personal protection against mosquitoes (especially insecticide-treated nets) combined with chemoprophylaxis according to the risk level.


Subject(s)
Communicable Diseases, Imported/drug therapy , Communicable Diseases, Imported/prevention & control , Malaria/prevention & control , Antimalarials/therapeutic use , Child , Decision Trees , France , Humans , Practice Guidelines as Topic , Severity of Illness Index
5.
Med Mal Infect ; 48(4): 238-249, 2018 Jun.
Article in English | MEDLINE | ID: mdl-29422423

ABSTRACT

INTRODUCTION: Artesunate and other artemisinin derivatives are used in various infectious and non-infectious diseases. We aimed to analyze available data on artesunate and artemisinin derivatives activity in humans and their potential clinical benefits in non-malarial indications. MATERIAL AND METHODS: Literature review performed on PubMed and the Cochrane Library databases using the PRISMA method. We analyzed studies published in English from January 2008 to August 2017 using the same indicators of drug efficacy. RESULTS: We included 19 studies performed in humans (1 meta-analysis, 1 literature review, 4 randomized controlled trials, 3 prospective controlled trials, 3 prospective uncontrolled trials, 2 exploratory phase 1 or 2 trials, 1 case series, and 4 case reports). Artesunate and artemisinin derivatives demonstrated efficacy in the treatment of schistosomiasis in combination with praziquantel (P=0.003). Artesunate monotherapy was less effective than praziquantel alone (P<0.001) probably because its activity only affects the early stages of Schistosoma parasites. Artesunate monotherapy could be interesting as a chemoprophylactic drug against schistosomiasis (P<0.001). Findings seem promising but are still controversial in the treatment of multidrug-resistant CMV infections. Studies do not conclude on artesunate and artemisinin derivatives efficacy in the treatment of cervix, breast, colorectal, and lung cancers. CONCLUSION: Artesunate and artemisinin derivatives in combination with praziquantel were effective against schistosomiasis, and could be used as a chemoprophylactic drug alone. They could be interesting as anti-CMV and anti-tumor treatment. Additional trials in humans are required to assess the efficacy of artesunate and artemisinin derivatives in diseases other than malaria.


Subject(s)
Artesunate/therapeutic use , Artemisinins/therapeutic use , Drug Therapy , Humans
6.
Clin Infect Dis ; 57(3): 370-80, 2013 Aug.
Article in English | MEDLINE | ID: mdl-23633111

ABSTRACT

BACKGROUND: Cutaneous leishmaniasis (CL) is a disfiguring but not life-threatening disease. Because antileishmanial drugs are potentially toxic, the World Health Organization (WHO) recommends simple wound care or local therapy as first-line treatment, followed or replaced by systemic therapy if local therapy fails or cannot be performed. METHODS: To determine the feasibility and impact of the recommended approach, we analyzed the results of a centralized referral treatment program in 135 patients with parasitologically proven CL. RESULTS: Infections involved 10 Leishmania species and were contracted in 29 different countries. Eighty-four of 135 patients (62%) were initially treated without systemic therapy. Of 109 patients with evaluable charts, 23 of 25 (92%) treated with simple wound care and 37 of 47 (79%) treated with local antileishmanial therapy were cured by days 42-60. In 37 patients with large or complex lesions, or preexisting morbidities, or who had not been cured with local therapy, the cure rate with systemic antileishmanial agents was 60%. Systemic adverse events were observed in 15 patients, all receiving systemic therapy. CONCLUSIONS: In this population of CL patients displaying variable degrees of complexity and severity, almost two-thirds of patients could be initially managed without systemic therapy. Of these, 60 were cured before day 60. The WHO-recommended stepwise approach favoring initial local therapy therefore resulted in at least 44% of all patients being cured without exposure to the risk of systemic adverse events. Efforts are needed to further simplify local therapy of CL and to improve the management of patients with complex lesions and/or preexisting comorbidities.


Subject(s)
Antiprotozoal Agents/therapeutic use , Bandages , Leishmaniasis, Cutaneous/therapy , Travel , Administration, Topical , Adolescent , Adult , Aged , Aged, 80 and over , Child , Child, Preschool , Female , Humans , Infant , Male , Middle Aged , Treatment Outcome , Young Adult
7.
Plant Biol (Stuttg) ; 15(1): 1-12, 2013 Jan.
Article in English | MEDLINE | ID: mdl-23121044

ABSTRACT

All memory functions have molecular bases, namely in signal reception and transduction, and in storage and recall of information. Thus, at all levels of organisation living organisms have some kind of memory. In plants one may distinguish two types. There are linear pathways from reception of signals and propagation of effectors to a type of memory that may be described by terms such as learning, habituation or priming. There is a storage and recall memory based on a complex network of elements with a high degree of integration and feedback. The most important elements envisaged are calcium waves, epigenetic modifications of DNA and histones, and regulation of timing via a biological clock. Experiments are described that document the occurrence of the two sorts of memory and which show how they can be distinguished. A schematic model of plant memory is derived as emergent from integration of the various modules. Possessing the two forms of memory supports the fitness of plants in response to environmental stimuli and stress.


Subject(s)
Feedback, Physiological , Models, Biological , Plants/genetics , Signal Transduction , Biological Clocks , Calcium/metabolism , Epigenomics , Plant Physiological Phenomena , Stress, Physiological , Time Factors
8.
Parasite ; 19(2): 147-51, 2012 May.
Article in English | MEDLINE | ID: mdl-22550625

ABSTRACT

The microsporidian species Enterocytozoon bieneusi is a major cause of chronic diarrhea and malabsorption in patients with AIDS. Genotyping was performed on seven E. bieneusi strains for the first time in Tunisia. All the strains were isolated from stool samples of humans with immunodeficiency virus (HIV) infection. Analysis of the ribosomal RNA gene internal transcribed spacer (rDNA ITS) allowed the identification of three distinct genotypes previously described in other studies. Genotypes D and B were characterized in four and two respectively. The Peruvian genotype (Peru 8) was detected in the last isolate. These results indicate a genetic diversity in E. bieneusi strains from HIV Tunisian patients and suggest the coexistence of both zoonotic and anthroponotic route of transmission.


Subject(s)
Enterocytozoon/classification , HIV Infections/complications , Microsporidiosis/parasitology , Adult , Base Sequence , DNA, Protozoan/chemistry , Enterocytozoon/genetics , Enterocytozoon/isolation & purification , Feces/parasitology , Female , Genotype , HIV Infections/epidemiology , Humans , Immunocompromised Host , Infant , Male , Microsporidiosis/epidemiology , Molecular Sequence Data , Polymerase Chain Reaction , RNA, Ribosomal/genetics , Sequence Alignment , Sequence Analysis, DNA , Tunisia/epidemiology , Young Adult
9.
Parasite ; 17(4): 321-8, 2010 Dec.
Article in English | MEDLINE | ID: mdl-21275238

ABSTRACT

To determine the prevalence and the species spectrum of intestinal parasites (IP) involved in hospitalized AIDS patients, a prospective observational and cross-sectional study was carried out in the four main hospitals in Kinshasa, Democratic Republic of the Congo. From November 2006 through September 2007, a single stool sample was collected from 175 hospitalized AIDS patients older than 15 years. Parasites were detected by light microscopy, including Ziehl-Neelsen, Fungi-Fluor, modified trichrome stains, and by immunofluorescence antibody tests and PCR for species diagnosis of microsporidia. At baseline, 19 patients (10.8%) were under antiretroviral therapy and 156 (89.2%) were eligible for ART. The main diagnosis for justifying hospitalization was intestinal infection associated with diarrhea in 87 out of 175 (49.7%). 47 out of 175 (26.9%) were found to harbor an IP, and 27 out of 175 (15.4%) were infected with at least one opportunistic IP (OIP). Prevalence rate for OIP were 9.7%, 5.1%, 1.7% and 0.6% for Cryptosporidium sp., Enterocytozoon bieneusi, Isospora belli and Encephalitozoon intestinalis respectively. Considering patients with diarrhea only, prevalence rate were 12.6%, 4.6%, 3.4% and 1.1% respectively. The other IP observed were Entamoeba histolytica/Entamoeba dispar in nine cases (5.1%), Ascoris lumbricoides in seven cases (4.0%), Giardia intestinalis in three cases (1.7%), hookworm in two cases (1.1%) and Trichiuris trichiura, Enterobius vermicularis, Schistosoma mansoni in one patient each (0.6%). No significant relationship was established between any individual IP and diarrhea. These results underline the importance of OIP in symptomatic AIDS patients regardless of diarrhea at the time of the hospitalisation, and showed that routine microscopic examination using stains designed for Cryptosporidium spp. or the microsporidia should be considered due to the absence of clinical markers.


Subject(s)
Acquired Immunodeficiency Syndrome/complications , Acquired Immunodeficiency Syndrome/parasitology , Intestinal Diseases/parasitology , Parasitic Diseases/epidemiology , Acquired Immunodeficiency Syndrome/drug therapy , Adolescent , Adult , Anti-Retroviral Agents/therapeutic use , Cross-Sectional Studies , Democratic Republic of the Congo/epidemiology , Diarrhea/parasitology , Female , Hospitalization , Humans , Intestinal Diseases/epidemiology , Male , Middle Aged , Prevalence
10.
Ann Trop Med Parasitol ; 102(8): 693-8, 2008 Dec.
Article in English | MEDLINE | ID: mdl-19000386

ABSTRACT

There are no established guidelines for the treatment of disseminated strongyloidiasis in immunosuppressed patients, and many different treatment regimens have been used. Here, the case of a 48-year-old, HIV-positive, Congolese man, who was hospitalized for disseminated tuberculosis but developed life-threatening disseminated strongyloidiasis, is described. This patient died, with relapsing disseminated strongyloidiasis, 3 months after being treated with ivermectin. The reasons for this poor outcome and the various treatment options for strongyloidiasis in HIV-infected patients are discussed.


Subject(s)
Antinematodal Agents/therapeutic use , HIV Seropositivity , Ivermectin/therapeutic use , Lung Diseases, Parasitic/drug therapy , Strongyloides stercoralis , Strongyloidiasis/drug therapy , Animals , Fatal Outcome , Humans , Immunocompromised Host , Lung Diseases, Parasitic/virology , Male , Middle Aged , Recurrence , Strongyloidiasis/virology , Tuberculosis/parasitology , Tuberculosis/virology
11.
Parasite ; 15(3): 349-58, 2008 Sep.
Article in English | MEDLINE | ID: mdl-18814706

ABSTRACT

Human microsporidian infections have emerged following the onset of the AIDS pandemic. Microsporidia are unicellular eukaryotic parasites that form spores. They are an exceptionally diverse group of parasites that infect a wide range of eukaryotic cells in numerous invertebrate and vertebrate hosts. Of the 14 species newly described as pathogens in human, Enterocytozoon bieneusi, which causes gastrointestinal diseases, is the most common agent of human infections. In the past fifteen years, E. bieneusi was also identified in environmental sources, especially in surface water, as well as in wild, domestic and farm animals. These findings raised concerns for waterborne, foodborne and zoonotic transmission. Molecular analyses of the 243-bp internal Transcribed spacer-(ITS) of the rRNA gene have revealed a considerable genetic variation within E. bieneusi isolates of human and animal origins, supporting the potential for zoonotic transmission. The focus of this revue is to present and discuss recent advances in diagnosis and zoonotic potential of E. bieneusi infections.


Subject(s)
Enterocytozoon/classification , Enterocytozoon/physiology , Microsporidiosis/epidemiology , Microsporidiosis/microbiology , Molecular Epidemiology , Zoonoses , AIDS-Related Opportunistic Infections/epidemiology , AIDS-Related Opportunistic Infections/parasitology , AIDS-Related Opportunistic Infections/transmission , Animals , DNA, Ribosomal Spacer/genetics , Diagnosis, Differential , Enterocytozoon/isolation & purification , Humans , Microsporidiosis/transmission , Microsporidiosis/veterinary , Sequence Analysis, DNA , Species Specificity , Spores, Fungal
12.
J Phys Chem B ; 112(17): 5534-46, 2008 May 01.
Article in English | MEDLINE | ID: mdl-18399679

ABSTRACT

Localizing two or more components of assemblies in biological systems requires both continued development of fluorescence techniques and invention of entirely new techniques. Candidates for the latter include dynamic secondary ion mass spectrometry (D-SIMS). The latest generation of D-SIMS, the Cameca NanoSIMS 50, permits the localization of specific, isotopically labeled molecules and macromolecules in sections of biological material with a resolution in the tens of nanometers and with a sensitivity approaching in principle that of a single protein. Here we use two different systems, crystals of glycine and mixtures of proteins, to show that the formation of recombinant CN secondary ions under Cs bombardment can be exploited to create a new colocalization technique. We show experimentally that the formation of the recombinant (13)C(15)N secondary ion between (13)C- and (15)N-labeled macromolecules is indeed an indicator of the distance between the interacting macromolecules and on their shape. We build up a convolution model of the mixing-recombination process in D-SIMS that allows quantitative interpretations of the distance-dependent formation of the recombinant CN. Our results show that macromolecules can be colocalized if they are within 2 nm of one another. We discuss the potential advantages of this new technique for biological applications.


Subject(s)
Escherichia coli Proteins/chemistry , Glycine/chemistry , Models, Biological , Spectrometry, Mass, Secondary Ion/methods , Carbon Isotopes , Crystallization , Escherichia coli/chemistry , Escherichia coli/metabolism , Escherichia coli Proteins/biosynthesis , Escherichia coli Proteins/isolation & purification , Ions , Mathematics , Nitrogen Isotopes
13.
Parasite ; 15(1): 65-8, 2008 Mar.
Article in English | MEDLINE | ID: mdl-18416248

ABSTRACT

The purpose of the study was to obtain more reliable epidemiological data concerning Entamoeba (E.) histolytica infection in Tunisian food handlers using established molecular tools able to differentiate E. histolytica from E. dispar. From 2002 to 2005, 4,266 fresh stools specimens received in the setting of the National program of food handlers' control were analysed by optical microscopy. Twelve (2.8 per thousand) were positive for the presence of four nuclei cysts identified as E. histolytica/E. dispar. Extraction of DNA from the 12 samples, followed by specific amplifications of E. histolytica and E. dispar SSU rDNA, showed that 11 samples (92%) were positive for E. dispar and negative for E. histolytica. Sequencing analysis of 8 PCR products permitted to verify the results obtained with conventional PCR. The remaining sample was negative by PCR amplifying E. histolytica DNA or E. dispar DNA specifically, although it did not show any inhibition. It probably contains protozoan cysts genetically distinct from these two species but morphological similar. Estimation of relative proportions between E. histolytica and E. dispar in cyst carriers showed that all explored individuals harboured the non pathogenic E. dispar strains. This result highlights the need of use in this population of complementary tests that allow specific diagnosis and obviate unnecessary chemotherapy.


Subject(s)
Entamoeba histolytica/isolation & purification , Entamoeba/isolation & purification , Entamoebiasis/diagnosis , Food Contamination/prevention & control , Adult , Animals , DNA, Protozoan/analysis , DNA, Ribosomal/analysis , Entamoebiasis/epidemiology , Entamoebiasis/transmission , Feces/parasitology , Female , Food Contamination/analysis , Food Handling , Food Parasitology , Gene Amplification , Humans , Male , Polymerase Chain Reaction/methods , Sequence Alignment , Sequence Analysis, DNA , Species Specificity , Tunisia/epidemiology
14.
Med Trop (Mars) ; 67(2): 145-8, 2007 Apr.
Article in French | MEDLINE | ID: mdl-17691432

ABSTRACT

In the Democratic Republic of Congo (DRC), as in many African countries, AIDS and its procession of opportunistic infections are a major cause of morbidity and mortality. In Kinshasa, the estimated prevalence rate of HIV-infected persons is between 4 and 5%, corresponding to more than 200,000 people. Due to the lack of trained laboratory personnel and appropriate diagnostic equipment, no local investigation has been carried out to determine the prevalence of the opportunistic digestive parasitic infection in HIV-infected persons. As a step to obtaining this information that is needed for implementation of an adequate care policy, a preliminary investigation was carried out in Paris, France on 50 stool samples from 50 AIDS-patients hospitalized in 3 reference hospitals in Kinshasa. Eleven patients (22%) had digestive symptoms with a diarrhea syndrome. Further study using specialized techniques demonstrated 2 cases of digestive infection related to opportunistic parasites (4%). The first involved a Cryptosporidium sp. The second represented the first case of Enterocytozoon bieneusi infection reported in the literature from the DRC.


Subject(s)
AIDS-Related Opportunistic Infections/epidemiology , Intestinal Diseases, Parasitic/epidemiology , AIDS-Related Opportunistic Infections/parasitology , Adult , Democratic Republic of the Congo/epidemiology , Diarrhea/parasitology , Female , Humans , Intestinal Diseases, Parasitic/parasitology , Male , Middle Aged , Prevalence
15.
Médecine Tropicale ; 67(2): 145-148, 2007. tables
Article in French | AIM (Africa) | ID: biblio-1266759

ABSTRACT

En Republique Democratique du Congo (RDC); comme dans de nombreux pays africains; le sida et son cortege d'infections opportunistes sont une cause majeure de morbidite et de mortalite. A Kinshasa; on estime entre 4 et 5le taux de prevalence de sujets infectes par le VIH; soit plus de 200 000 personnes (chiffres du Programme National de Lutte contre le Sida; PNLS 2005). A ce jour; faute de personnels formes et de moyens diagnostiques adaptes; aucune enquete n'a encore ete menee sur la prevalence des parasites opportunistes digestifs dans la population des patients infectes par leVIH; prealable indispensable a la mise en place d'une politique de soin adaptee. Une enquete preliminaire a ete realisee a Paris sur 50 echantillons de selles de 50 patients malades du sida; hospitalises dans 3 hopitaux de references de Kinshasa. Onze patients (22) avaient une symptomatologie digestive avec un syndrome diarrheique. La realisation des examens specialises a mis en evidence 2 cas d'infection digestive par des parasitoses opportunistes (4); une a Cryptosporidium sp. et une a Enterocytozoon bieneusi; premier cas decrit dans la litterature en RDC


Subject(s)
Humans , AIDS-Related Opportunistic Infections/epidemiology , Cryptosporidium , Enterocytozoon , Acquired Immunodeficiency Syndrome , HIV , Microsporidia
16.
Médecine Tropicale ; 67(2): 145-148, 2007. tables
Article in French | AIM (Africa) | ID: biblio-1266764

ABSTRACT

En Republique Democratique du Congo (RDC); comme dans de nombreux pays africains; le sida et son cortege d'infections opportunistes sont une cause majeure de morbidite et de mortalite. A Kinshasa; on estime entre 4 et 5le taux de prevalence de sujets infectes par le VIH; soit plus de 200 000 personnes (chiffres du Programme National de Lutte contre le Sida; PNLS 2005).A ce jour; faute de personnels formes et de moyens diagnostiques adaptes; aucune enquete n'a encore ete menee sur la prevalence des parasites opportunistes digestifs dans la population des patients infectes par leVIH; prealable indispensable a la mise en place d'une politique de soin adaptee. Une enquete preliminaire a ete realisee a Paris sur 50 echantillons de selles de 50 patients malades du sida; hospitalises dans 3 hopitaux de references de Kinshasa. Onze patients (22) avaient une symptomatologie digestive avec un syndrome diarrheique. La realisation des examens specialises a mis en evidence 2 cas d'infection digestive par des parasitoses opportunistes (4); une a Cryptosporidium sp. et une a Enterocytozoon bieneusi; premier cas decrit dans la litterature en RDC


Subject(s)
Enterocytozoon
17.
Anal Chem ; 78(8): 2471-7, 2006 Apr 15.
Article in English | MEDLINE | ID: mdl-16615752

ABSTRACT

We describe the measurement, at 100 K, of the SIMS relative sensitivity factors (RSFs) of the main physiological cations Na+, K+, Mg2+, and Ca2+ in frozen-hydrated (F-H) ionic solutions. Freezing was performed by either plunge freezing or high-pressure freezing. We also report the measurement of the RSFs in flax fibers, which are a model for ions in the plant cell wall, and in F-H ionic samples, which are a model for ions in the vacuole. RSFs were determined under bombardment with neutral oxygen (FAB) for both the fibers and the F-H samples. We show that referencing to ice-characteristic secondary ions is of little value in determining RSFs and that referencing to K is preferable. The RSFs of Na relative to K and of Ca relative to Mg in F-H samples are similar to their respective values in fiber samples, whereas the RSFs of both Ca and Mg relative to K are lower in fibers than in F-H samples. Our data show that the physical factors important for the determination of the RSFs are not the same in F-H samples and in homogeneous matrixes. Our data show that it is possible to perform a SIMS relative quantification of the cations in frozen-hydrated samples with an accuracy on the order of 15%. Referencing to K permits the quantification of the ionic ratios, even when the absolute concentration of the referencing ion is unknown. This is essential for physiological studies of F-H biological samples.

18.
Plant Signal Behav ; 1(1): 9-14, 2006 Jan.
Article in English | MEDLINE | ID: mdl-19521470

ABSTRACT

Plants are sensitive to stimuli from the environment (e.g., wind, rain, contact, pricking, wounding). They usually respond to such stimuli by metabolic or morphogenetic changes. Sometimes the information corresponding to a stimulus may be "stored" in the plant where it remains inactive until a second stimulus "recalls" this information and finally allows it to take effect. Two experimental systems have proved especially useful in unravelling the main features of these memory-like processes.In the system based on Bidens seedlings, an asymmetrical treatment (e.g., pricking, or gently rubbing one of the seedling cotyledons) causes the cotyledonary buds to grow asymmetrically after release of apical dominance by decapitation of the seedlings. This information may be stored within the seedlings, without taking effect, for at least two weeks; then the information may be recalled by subjecting the seedlings to a second, appropriate, treatment that permits transduction of the signal into the final response (differential growth of the buds). Whilst storage is an irreversible, all-or-nothing process, recall is sensitive to a number of factors, including the intensity of these factors, and can readily be enabled or disabled. In consequence, it is possible to recall the stored message several times successively.In the system based on flax seedlings, stimulation such as manipulation stimulus, drought, wind, cold shock and radiation from a GSM telephone or from a 105 GHz Gunn oscillator, has no apparent effect. If, however, the seedlings are subjected at the same time to transient calcium depletion, numerous epidermal meristems form in their hypocotyls. When the calcium depletion treatment is applied a few days after the mechanical treatment, the time taken for the meristems to appear is increased by a number of days exactly equal to that between the application of the mechanical treatment and the beginning of the calcium depletion treatment. This means that a meristem-production information corresponding to the stimulation treatment has been stored in the plants, without any apparent effect, until the calcium depletion treatment recalls this information to allow it to take effect. Gel electrophoresis has shown that a few protein spots are changed (pI shift, appearance or disappearance of a spot) as a consequence of the application of the treatments that store or recall a meristem-production signal in flax seedlings. A SIMS investigation has revealed that the pI shift of one of these spots is probably due to protein phosphorylation. Modifications of the proteome have also been observed in Arabidopsis seedlings subjected to stimuli such as cold shock or radiation from a GSM telephone.

19.
Plant Biol (Stuttg) ; 6(5): 590-7, 2004 Sep.
Article in English | MEDLINE | ID: mdl-15375730

ABSTRACT

When subjected to an appropriate asymmetric stimulus, seedlings of Bidens pilosa L. "store" a symmetry-breaking instruction that will finally take effect (in the form of a differential growth of the cotyledonary buds) only if the plants are in a state in which they can "recall" this information. The ability of the plants to recall the stored symmetry-breaking instruction may be switched "on" or "off" by the application of a variety of stimuli. Although its detailed phenomenology is rather complicated, the overall behaviour of the plant storage/recall system can be modelled by use of an asynchronous, logical (discrete) description involving positive and negative feedback circuits, which are required for the existence of multi-stationarity and stability, respectively. The state tables, as used in this formalism, give a concise and easy-to-handle description of the evolution of the system and make it particularly easy to determine its stable states. This modelling approach may be extended to the formulation of many other experimental systems.


Subject(s)
Plant Development , Biological Clocks , Environment , Feedback , Models, Biological , Plant Physiological Phenomena , Seedlings/growth & development , Signal Transduction
20.
J Appl Microbiol ; 94(2): 273-9, 2003.
Article in English | MEDLINE | ID: mdl-12534819

ABSTRACT

AIMS: Microsporidia have become widely recognized as important human pathogens. Among Microsporidia, Enterocytozoon bieneusi is responsible for severe gastrointestinal disease. To date, no current therapy has been proven effective. Their mode of transmission and environmental occurrence are poorly documented because of the lack of detection methods that are both species-specific and sensitive. In this study, we developed a sensitive and specific molecular method to detect E. bieneusi spores in water samples. METHODS AND RESULTS: The molecular assay combined immunomagnetic separation (IMS) and polymerase chain reaction (PCR) amplification to detect E. bieneusi spores. A comparison was made of IMS magnetic beads coated with two different monoclonal antibodies, one specific for the Encephalitozoon genus that cross-reacts with E. bieneusi and the other specific only for the E. bieneusi species itself. CONCLUSIONS: Immunotech beads coated with the antibody specific for E. bieneusi were found to be the most effective combination. SIGNIFICANCE AND IMPACT OF THE STUDY: The highly specific IMS-PCR assay developed in this study provides a rapid and sensitive means of screening water samples for the presence of E. bieneusi spores.


Subject(s)
Enterocytozoon/isolation & purification , Immunomagnetic Separation/methods , Polymerase Chain Reaction/methods , Water Microbiology , Antibodies, Protozoan/analysis , DNA, Protozoan/analysis , Feces/microbiology , Humans , Microsporidiosis/microbiology , Sensitivity and Specificity
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