RESUMEN
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.
Asunto(s)
Enfermedades Transmisibles Importadas , Malaria , Resultado del Embarazo , Humanos , Femenino , Embarazo , Estudios Retrospectivos , Adulto , Francia/epidemiología , Resultado del Embarazo/epidemiología , Malaria/epidemiología , Enfermedades Transmisibles Importadas/epidemiología , Recién Nacido , Adulto Joven , Persona de Mediana Edad , Complicaciones Parasitarias del Embarazo/epidemiología , Mortinato/epidemiología , Nacimiento Prematuro/epidemiología , Viaje/estadística & datos numéricos , Recién Nacido de Bajo Peso , Aborto Espontáneo/epidemiologíaRESUMEN
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.
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Antiprotozoarios/uso terapéutico , Vendajes , Leishmaniasis Cutánea/terapia , Viaje , Administración Tópica , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Niño , Preescolar , Femenino , Humanos , Lactante , Masculino , Persona de Mediana Edad , Resultado del Tratamiento , Adulto JovenRESUMEN
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.
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Enterocytozoon/clasificación , Infecciones por VIH/complicaciones , Microsporidiosis/parasitología , Adulto , Secuencia de Bases , ADN Protozoario/química , Enterocytozoon/genética , Enterocytozoon/aislamiento & purificación , Heces/parasitología , Femenino , Genotipo , Infecciones por VIH/epidemiología , Humanos , Huésped Inmunocomprometido , Lactante , Masculino , Microsporidiosis/epidemiología , Datos de Secuencia Molecular , Reacción en Cadena de la Polimerasa , ARN Ribosómico/genética , Alineación de Secuencia , Análisis de Secuencia de ADN , Túnez/epidemiología , Adulto JovenRESUMEN
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.
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Síndrome de Inmunodeficiencia Adquirida/complicaciones , Síndrome de Inmunodeficiencia Adquirida/parasitología , Enfermedades Intestinales/parasitología , Enfermedades Parasitarias/epidemiología , Síndrome de Inmunodeficiencia Adquirida/tratamiento farmacológico , Adolescente , Adulto , Antirretrovirales/uso terapéutico , Estudios Transversales , República Democrática del Congo/epidemiología , Diarrea/parasitología , Femenino , Hospitalización , Humanos , Enfermedades Intestinales/epidemiología , Masculino , Persona de Mediana Edad , PrevalenciaRESUMEN
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.
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Malaria/epidemiología , Animales , Enfermedades Transmisibles Importadas/epidemiología , Francia/epidemiología , Salud Global , Humanos , Incidencia , Factores de TiempoRESUMEN
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.
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Enfermedades Transmisibles Importadas/tratamiento farmacológico , Enfermedades Transmisibles Importadas/prevención & control , Malaria/prevención & control , Antimaláricos/uso terapéutico , Niño , Árboles de Decisión , Francia , Humanos , Guías de Práctica Clínica como Asunto , Índice de Severidad de la EnfermedadRESUMEN
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.
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Proteínas de Escherichia coli/química , Glicina/química , Modelos Biológicos , Espectrometría de Masa de Ion Secundario/métodos , Isótopos de Carbono , Cristalización , Escherichia coli/química , Escherichia coli/metabolismo , Proteínas de Escherichia coli/biosíntesis , Proteínas de Escherichia coli/aislamiento & purificación , Iones , Matemática , Isótopos de NitrógenoRESUMEN
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.
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Enterocytozoon/clasificación , Enterocytozoon/fisiología , Microsporidiosis/epidemiología , Microsporidiosis/microbiología , Epidemiología Molecular , Zoonosis , Infecciones Oportunistas Relacionadas con el SIDA/epidemiología , Infecciones Oportunistas Relacionadas con el SIDA/parasitología , Infecciones Oportunistas Relacionadas con el SIDA/transmisión , Animales , ADN Espaciador Ribosómico/genética , Diagnóstico Diferencial , Enterocytozoon/aislamiento & purificación , Humanos , Microsporidiosis/transmisión , Microsporidiosis/veterinaria , Análisis de Secuencia de ADN , Especificidad de la Especie , Esporas FúngicasRESUMEN
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.
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Entamoeba histolytica/aislamiento & purificación , Entamoeba/aislamiento & purificación , Entamebiasis/diagnóstico , Contaminación de Alimentos/prevención & control , Adulto , Animales , ADN Protozoario/análisis , ADN Ribosómico/análisis , Entamebiasis/epidemiología , Entamebiasis/transmisión , Heces/parasitología , Femenino , Contaminación de Alimentos/análisis , Manipulación de Alimentos , Parasitología de Alimentos , Amplificación de Genes , Humanos , Masculino , Reacción en Cadena de la Polimerasa/métodos , Alineación de Secuencia , Análisis de Secuencia de ADN , Especificidad de la Especie , Túnez/epidemiologíaRESUMEN
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.
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Artesunato/uso terapéutico , Artemisininas/uso terapéutico , Quimioterapia , HumanosRESUMEN
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.
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Infecciones Oportunistas Relacionadas con el SIDA/epidemiología , Parasitosis Intestinales/epidemiología , Infecciones Oportunistas Relacionadas con el SIDA/parasitología , Adulto , República Democrática del Congo/epidemiología , Diarrea/parasitología , Femenino , Humanos , Parasitosis Intestinales/parasitología , Masculino , Persona de Mediana Edad , PrevalenciaRESUMEN
In the particular case of boron and lithium we examine the possibilities of using stable isotopes for experiments of isotopic labelling and microlocalization, as no radioisotopes exist. The detection is made with the help of a specific nuclear reaction, using homogeneous detectors. The first experimental applications are given: transepithelial fluxes of lithium (frog skin) have shown Liefflux values larger than the influx ones. Detailed microlocalization of lithium have been made on histological preparations of mice having received lithium treatment: particularly important contents are found in the hypophysis, the salivary glands, the bladder, the kidney (especially the pelvis), the intestinal system and certain parts of the brain (particularly the hippocampus); the liver, however remains very poor in lithium. Physiological implications are examined.
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Boro/análisis , Litio/análisis , Animales , Histocitoquímica , Marcaje Isotópico/métodos , Isótopos , Riñón/ultraestructura , Matemática , Ratones , Física Nuclear , Especificidad de ÓrganosRESUMEN
The compartmental analysis of sulphate transport in cells of Lemna plants has been performed, taking into account the growth of the samples and the metabolization of sulphate into organic thiocompounds during the course of the experiment. The results obtained form efflux and influx experiments are fully consistent with one another. Both unidirectional fluxes between the external medium and the cell wall are very large (order of magnitude of 1 MUMOL/h per g fresh weight of plants). All the other unidirectional fluxes, including the flux of sulphate metabolization, are much smaller (from about 10 to 60 nmol/h per g). Over 70% of the total sulphur of the plant corresponds to that incorporated into organic thio compounds, and over 25% to free sulphate in the vacuola. The pool of free sulphate in the cytoplasm is only about 1% of the total sulphur, and the sulphate content of the cell wall (free spaces) is also about 1%. Two remarks of general relevance have been made concerning the influx curves. First, these curves exhibit a long (several hours), quasi-stationary phase after the first few minutes of absorption, though the slope of this straight line does not correspond to the unidirectional flux of sulphate entry through the plasmalemma (from cell wall to cytoplasm). Second, the Lemna plants seem to be sensitive to the effect of "gas shock'.
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Plantas/metabolismo , Sulfatos/metabolismo , Transporte Biológico , Cinética , Matemática , Modelos Biológicos , Desarrollo de la PlantaRESUMEN
We describe a new tracer method to measure unidirectional fluxes of Li+ despite the lack of any utilizable radioisotope of lithium. This method uses the purified stable isotopes, 6Li and 7Li, detected with an ion-probe microanalyser. The accuracy is comparable to that obtained for other ions (e.g., Na+) with radiotracers. The method has been applied to frog skin with both faces bathed in a 20% lithium/80% sodium medium. Sodium and lithium unidirectional fluxes have been measured simultaneously. The results are consistent with lithium being actively pumped, the outflux of lithium being, however, much larger than that of sodium.
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Litio/metabolismo , Piel/metabolismo , Animales , Anuros , Transporte Biológico Activo , Marcaje Isotópico , Isótopos , Cinética , Rana esculentaRESUMEN
Using secondary ion mass spectrometry (SIMS), calcium was imaged in cambium cells and in the adjacent secondary phloem and xylem cells during the different phases of cambium functioning in beech (Fagus sylvatica L.). At the end of the period of quiescence, immediately before the resumption of cell divisions (i.e. at the cambium pre-activation phase), a strong temporary increase of calcium concentration was observed to take place in cambium and phloem but not in xylem cells.
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Calcio/análisis , Calcio/metabolismo , Brotes de la Planta/citología , Brotes de la Planta/metabolismo , Árboles/metabolismo , Procesamiento de Imagen Asistido por Computador , Estaciones del Año , Espectrometría de Masa de Ion Secundario/métodosRESUMEN
A myriad different constituents or elements (genes, proteins, lipids, ions, small molecules etc.) participate in numerous physico-chemical processes to create bacteria that can adapt to their environments to survive, grow and, via the cell cycle, reproduce. We explore the possibility that it is too difficult to explain cell cycle progression in terms of these elements and that an intermediate level of explanation is needed. This level is that of hyperstructures. A hyperstructure is large, has usually one particular function, and contains many elements. Non-equilibrium, or even dissipative, hyperstructures that, for example, assemble to transport and metabolize nutrients may comprise membrane domains of transporters plus cytoplasmic metabolons plus the genes that encode the hyperstructure's enzymes. The processes involved in the putative formation of hyperstructures include: metabolite-induced changes to protein affinities that result in metabolon formation, lipid-organizing forces that result in lateral and transverse asymmetries, post-translational modifications, equilibration of water structures that may alter distributions of other molecules, transertion, ion currents, emission of electromagnetic radiation and long range mechanical vibrations. Equilibrium hyperstructures may also exist such as topological arrays of DNA in the form of cholesteric liquid crystals. We present here the beginning of a picture of the bacterial cell in which hyperstructures form to maximize efficiency and in which the properties of hyperstructures drive the cell cycle.
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Bacterias/citología , Bacterias/metabolismo , Ciclo Celular/fisiología , Modelos Biológicos , Bacterias/genética , Replicación del ADN , Genes Bacterianos , Sustancias Macromoleculares , Orgánulos/metabolismoRESUMEN
Boronated antibodies have already been evaluated as agents in neutron capture therapy. Because the boronation procedure may alter the properties of the antibody it is important to study the immunoreactivity of the conjugated antibody before in vivo use. In our studies of two dextran-boronated monoclonal antibodies, anti-glial fibrillary acidic protein antibody, and anti-hyaluronectin antibody, we have used ELISA and immunohistological methods to determine antibody activity and specificity. A ten-fold decrease in activity was observed for both antibodies in ELISA, and non-specific interactions were seen in both immunohistological and ELISA procedures. The boron compound used was shown to be at least partly responsible for these non-specific interactions.
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Anticuerpos Monoclonales/inmunología , Boro/inmunología , Animales , Especificidad de Anticuerpos , Proteínas Portadoras/inmunología , Ensayo de Inmunoadsorción Enzimática , Proteína Ácida Fibrilar de la Glía/inmunología , Receptores de Hialuranos , Inmunoglobulina G/inmunología , RatonesRESUMEN
The time-constant of lithium (Li)-clearance from the plasma was of the order of 2 hr, while the mean time-constant of lithium-clearance from the bulk of the body cells into the plasma was about 10 times this value. The mean time-constant of lithium ion (Li+)-clearance from various brain substructures (corpus callosum, striatum, hippocampus, neocortex) was comparable to the latter (15-25 hr). Comparison of samples where either a slight diffusion or no diffusion at all had occurred, suggest that between the nerve bodies and the trunks, lithium ions are not uniformly distributed.
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Encéfalo/metabolismo , Litio/metabolismo , Animales , Semivida , Isótopos , Cinética , Litio/sangre , Masculino , Ratones , TritioRESUMEN
Thanks to the "secondary-ion emission microscope" (CAMECA IMS 300), we have been able to image the distribution of the stable isotopes of nitrogen 14N and 15N in sections of plant roots (spatial resolution better than 1 micron), as well as to estimate the relative concentrations of these isotopes. The plants used (Lupinus spec.) originated from seeds with natural (i.e., 14N) nitrogen and had been fed for a few days with [15N]-nitrate before sampling. We have found in root sections of 6-day-old plants (prepared at 5 mm from the root tip) a clear-cut regionalization of the distribution of 15N between the vascular cylinder and the cortex. The latter contained approximately 5% 15N (of total nitrogen), whereas the relative concentration of the heavy isotope in the vascular cylinder was significantly lower. The observed concentration difference is probably due to the Casparian strip, which is a barrier for the apoplastic diffusion of solutes from the cortex to the vascular cylinder.