Radio frequency current-voltage probe for impedance and power measurements in multi-frequency unmatched loads.

A broad-band, inline current-voltage probe, with a characteristic impedance of 50 Ω, is presented for the measurement of voltage and current waveforms, impedance, and power in rf systems. The probe, which uses capacitive and inductive sensors to determine the voltage and current, respectively, can be used for the measurement of single or multi-frequency signals into both matched and unmatched loads, over a frequency range of about 1-100 MHz. The probe calibration and impedance/power measurement technique are described in detail, and the calibrated probe results are compared with those obtained from a vector network analyzer and other commercial power meters. Use of the probe is demonstrated with the measurement of power into an unmatched capacitively coupled plasma excited by multi-frequency tailored voltage waveforms.

Numerical response of a helminth community in the course of a multi-annual abundance cycle of the water vole (Arvicola terrestris).

The impact of parasitism on population dynamics is determined in part by the numerical responses of parasites during population fluctuations of their hosts. Vole populations fluctuate in multi-annual cycles allowing such responses to be studied over successive phases of population growth, abundance and decline. We investigate how a helminth community (5 nematode and 7 cestode species) evolved over a full 6-year Water Vole (Arvicola terrestris) population cycle. Brillouin and individual parasite species richness (IPSR) indices were used to measure the numerical response of the parasite community. We report a correlation between levels of parasite intensity and vole population cycle phases. Both indices were consistently higher during pre-decline and decline phases for male and female voles alike. The numerical response of the parasite community suggests that populations may be regulated by parasitism and that studies of this mechanism should allow both for the cyclic or non-cyclic character of the host populations and for the response of the broadest possible set of the local parasite community.

Frenkelia parasites in a small mammal community. Dynamics of infection and effect on the host.

A community of small mammals, Clethrionomys glareolus, Arvicola terrestris, Microtus arvalis, M. agrestis, M. subterraneus, Apodemus spp. and Sorex spp., was studied as hosts of Frenkelia glareoli and F. microti in Fronche-Comté (France). They were monitored in spring, summer and autumn on an area of about 1,350 ha comprising open field, hedgerow network and forest. Among 1,714 small mammals examined between July 1992 and October 1993, 47% (178/376) of C. glareolus, 9.9% (14/139) of A. terrestris and 1.3% (4/311) of Apodemus spp. were infected by F. glareoli. The prevalence of infection with F. microti was 9.2% (66/716) in M. arvalis and 8.2% (6/73) in M. agrestis. M. subterraneus and Sorex spp. were not infected. The maintenance of each parasite in a rural landscape is assured both by a forest and a grassland host. Multiple logistic regression showed that prevalence was highly age-dependent, with an apparent seasonal pattern. Prevalence varied between 30% in summer and 60% in early spring for F. glareoli in C. glareolus and between 3% in autumn to 30% in early spring for F. microti in M. arvalis. The year, habitat, host sex, relative density had no impact on prevalence. In M. arvalis only, sexually active voles were preferentially uninfected, indicating a possible impact of this parasitism on fertility.

[Mefloquine treatment in infants and children with Plasmodium falciparum malaria: an efficient and well tolerated treatment]. / La méfloquine chez le nourrisson et l'enfant lors de l'accès palustre simple à Plasmodium falciparum: un traitement efficace et bien toléré

OBJECTIVES: The aim of this study was to evaluate the efficacy and tolerance of mefloquine treatment in children, especially in infants of less than 15 kg, in an endemic area of malaria (French Guiana). METHOD: This 5-years (1996-2000) retrospective study included 61 children aged 6 months to 16 years who had been treated with mefloquine for acute Plasmodium falciparum malaria. Twenty-six of these children weighted less than 15 kg. The efficiency of the treatment was evaluated using clinical and parasitic data that had been validated according to the criteria of the World Health Organization (WHO). Tolerance was compared with the data in the medical literature. RESULTS: None of the 59 patients who were given the treatment correctly presented signs of early therapeutic failure as defined by the WHO. Apyrexia was obtained in 48 h on average (CI 95%: 39-57; median: 36 h). The mean time required to obtain negative parasitism was 91 h (CI 95%: 80-101; median: 96 h) among the 51 patients in whom this was measured. Mild side effects were observed in 27.8% of the cases affecting mainly the digestive system. No differences were observed regarding efficacy or tolerance for children who weighed less than 15 kg. CONCLUSION: Mefloquine represents an efficient treatment for acute uncomplicated P. falciparum malaria in children and is well-tolerated even in infants.

Echinococcus multilocularis: secondary poisoning of fox population during a vole outbreak reduces environmental contamination in a high endemicity area.

This paper describes the role of fox population level on Echinococcus multilocularis infection in foxes in a highly endemic area in eastern France. Fox population level was monitored by spotlight survey at Le Souillot from 1989 to 2000, and from 1992 to 2000 at Chemin, a control site located in a low endemic area. The infection level of the fox population was estimated at Le Souillot from winter 1995 to winter 1999 using a coproantigen ELISA performed on faeces collected in the field. Population biomass of intermediate hosts (Microtus arvalis and Arvicola terrestris) was monitored using index methods from 1995 to 1999. At Le Souillot, a significant decline in the fox population level was recorded after spring 1997 (P<0.001), and the population level remained low until 2000. The decline occurred when 31% of the grassland area was treated with bromadiolone, an anticoagulant used at a large scale for the control of A. terrestris population outbreaks. No decline of population was recorded at Chemin, where bromadiolone was not used for rodent control. Significant differences among ELISA OD distributions in fox faeces were recorded for the five winters under study at Le Souillot (P=0.0004). The median of ELISA OD distribution was 0.209 and 0.207 before the population decline (winter 1995 and 1996, respectively), significantly increased to 0.306 just after the decline (winter 1997), and then significantly decreased to 0.099 and 0.104 afterwards (winter 1998 and 1999, respectively). Therefore, the decrease in infection level occurred during winter 1998, 1 year after the population decline, when the intermediate host biomass in the field was at its highest. These results suggest a complex dependence between the fox population level and E. multilocularis infection in a high endemicity area. Alternative ways to control fox population as a way to reduce E. multilocularis transmission in a given area are discussed.

[Outcome at 2 years of very premature infants cared at the hospital of Cayenne in 1998]. / Devenir médicosocial à l'âge de 2 ans des grands prématurés pris en charge au centre hospitalier de Cayenne en 1998.

UNLABELLED: Perinatal mortality in French Guyana is twice as high as the national rates. Within a global project rallying all the people working around the birth, a catching up program benefited the neonatal unit of the Cayenne hospital in order to make up for the important lack of modern structures and means. OBJECTIVES: To establish some quality care for the less than 33 weeks preterm infants born in 1998, and to estimate the medical and familial future for these infants after they have reached 2 years of age. METHODS: All less than 33 weeks old infants born alive and admitted at the neonatology unit of the CHC were included in the study. The obstetrical and neonatal data were recorded from the medical files. A survey was conducted through a questionnaire including the familial and medical outcome and was led from december 1999 to july 2001. Results were analysed with Epi-info 6.0 software (CDC, Atlanta, USA). RESULTS: Eighty-eight infants issue from 78 pregnancies were included. Among them, 29 were transferred in utero and 12 were transferred after birth. The mothers' situations were mainly characterized by precariousness, a poor follow-up of the pregnancy (27% non-declared), a higher morbidity of their newborns. Neonatal results did not differ from national results from Epipage cohort in terms of gestational age (29.9 weeks), weight at birth (1411 g), mortality (90.9 alive when released from the hospital), morbidity, growth at 2. However, 26% were hypotrophic (15% in Epipage cohort) in relation with the 29% pregnancies complicated with hypertension. Four infants were suffering from acquisition retardation due to motor handicaps; 2 infants had severe socio-educative difficulties. The postnatal follow-up was mainly performed by the Mother and Children Health Centers. A third of medical exams were not recorded in the health book, sensory screening exams were not performed. The opening of a medicosocial actions center in 2001, will allow a prospective follow-up of this population. CONCLUSION: Early neonatal mortality decreased from 10.3 for 1000 births to 4.4 in 1998. This reflects the improvement of the new-born caring possibilities. However, an improvement of mortality rates will not be possible without a better pregnancy follow-up.

[The HIV infection in pregnant women in French Guiana]. / L'infection par le VIH chez la femme enceinte en Guyane française.

OBJECTIVE: The aim of this study is to analyse the characteristics of HIV pregnant women in French Guiana then to evaluate the HIV mother to child transmission rate (MTCT) and determine the pronostic factors associated with MTCT. PATIENTS AND METHOD: An epidemiological study has been led including all deliveries in French Guiana from January 1998 to December 2000. For each case a standardized questionnaire has been gathered including epidemiological, clinical and biological data and an univariate analysis has been realized. A hundred and forty-eight women have been included in the study among 135 women came for delivery. RESULTS: The factors associated with increased MTCT in our study were no antiretroviral therapy before delivery, the lack of follow-up during pregnancy and no antiretroviral therapy in children. The HIV mother to child transmission rate was 6,5% despite the availability of antiretroviral therapies. DISCUSSION AND CONCLUSION: This rate may be explained by the difficulties of follow-up in HIV infected women. Much more needs to be done to improve access to care for women coming from foreign countries. This may be indispensable to reduce the HIV mother to child transmission rate in French Guiana.

[Efficacy and tolerance of mefloquine in the treatment of infants and children with Plasmodium falciparum malaria]. / Efficacité et tolérance de la méfloquine dans le traitement du paludisme à Plasmodium falciparum du nourrisson et de l'enfant.

UNLABELLED: Only a limited number of treatments are available for use in young children with malaria. OBJECTIVES: The aim of this study was to evaluate the efficacy and tolerance of mefloquine treatment in children, especially in infants of less than 15 kg, in an endemic area of malaria (French Guiana). METHOD: This five-years (1996-2000) retrospective study included 61 children aged six months to 16 years who have been treated with mefloquine for acute P. falciparum malaria. Twenty-six of these children weighted less than 15 kg. The efficiency of the treatment was evaluated using clinical and parasitic data that had been validated according to the criteria of the World Health Organization (WHO). Tolerance was compared with the data in the medical literature. RESULTS: None of the 59 patients who were given the treatment correctly presented signs of early therapeutic failure as defined by the WHO. Apyrexia was obtained in 47.8 h on average (CI 95%: 39-57; median: 36 h). The mean time required to obtain negative parasitism was 90.8 h (CI 95%: 80-101; median: 96 h) among the 51 patients in whom this was measured. Mild side effects were observed in 27.8% of the cases affecting mainly the digestive system. No differences were observed regarding efficacy or tolerance for children who weighed less than 15 kg. CONCLUSION: Mefloquine represents an efficient treatment for acute uncomplicated P. falciparum malaria in children and is well tolerated even in infants.

Interactions between landscape changes and host communities can regulate Echinococcus multilocularis transmission.

An area close to the Qinghai-Tibet plateau region and subject to intensive deforestation contains a large focus of human alveolar echinococcosis while sporadic human cases occur in the Doubs region of eastern France. The current review analyses and compares epidemiological and ecological results obtained in both regions. Analysis of rodent species assemblages within quantified rural landscapes in central China and eastern France shows a significant association between host species for the pathogenic helminth Echinococcus multilocularis, with prevalences of human alveolar echinococcosis and with land area under shrubland or grassland. This suggests that at the regional scale landscape can affect human disease distribution through interaction with small mammal communities and their population dynamics. Lidicker's ROMPA hypothesis helps to explain this association and provides a novel explanation of how landscape changes may result in increased risk of a rodent-borne zoonotic disease.

An epidemiological and ecological study of human alveolar echinococcosis transmission in south Gansu, China.

Human alveolar echinococcosis (AE) is usually a rare, highly pathogenic zoonotic disease, transmitted across the northern hemisphere between fox and rodent hosts. In China the first cases were described in 1965; however very few epidemiological studies have been undertaken since. Following identification in 1991 of a serious focus of human AE in south Gansu province, detailed village-based community and ecological studies were carried out between 1994 and 1997. Hepatic ultrasound mass screening with serological testing (five tests) identified 84/2482 new AE cases (3%). An overall prevalence of 4.1% (135/3331) was recorded for the area when previous cases were also included. Based on a seropositive result only, without an ultrasound scan indication, no additional AE cases were identified. Of the evolutive AE cases, 96% were seropositive in at least one test, while up 15-20% of individuals who exhibited hepatic calcified lesions and 12-15% exhibiting hepatic nodular lesions were seropositive for specific Em2 or Em18 antibodies. Village (n=31) human AE prevalence rates varied from 0 to 15.8%. Questionnaire analysis indicated that total number of dogs owned over a period was a risk factor (P<0.006), but not a history of red fox hunting (P>0.6). Rodent ecology studies revealed an association between density indices of voles (Microtus limnophilus) and village AE prevalence rates, on the one hand, and village landscape characterised by a ratio of scrub/grassland to total area above 50% (P<0.005). Long-term transmission of Echinococcus multilocularis and risk of zoonotic infection of south Gansu farmers may be related ultimately to a process of deforestation driven by agriculture. This in turn probably results in creation of optimal peri-domestic habitats for rodents that serve as intermediate host species (such as M. limnophilus) and subsequent development of a peri-domestic cycle involving dogs.

[Ecological basis for molecular surveillance of microbes and parasites transmitted by rodents]. / Bases écologiques d'une veille moléculaire chez les microbes et parasites transmis par les rongeurs.

The multiplicity of circumstances by which a host can capture a microbiological agent can be broken down into two simplified processes: 1. encounter between host and microbe, 2. compatibility of two organisms. Given that rodents include species of generally small size, inhabiting continental areas in closer proximity to man than many other mammals, they offer numerous chain of contamination. Microbiological surveillance must both consider the emergence of old and new microbial types and identify ecological and demographic condition placing man at risk. Since it is materially impossible to survey all existing pathogens, priorities must be set according to empirical, epidemiological and ecological considerations. One of the major challenges is how to make microbiological surveillance more effective by way of new tools for detecting demographic changes in rodent populations.

Epidemiology of alveolar echinococcosis in Xinjiang Uygur autonomous region, China: a preliminary analysis.

The Xinjiang Uygur autonomous region (XUAR) in north-western China is known to be endemic for Echinococcosis multilocularis, the causative agent of human alveolar echinococcosis (HAE). Despite regular reports of HAE cases in their region, very little is known about the local epidemiology of the disease or the transmission of E. multilocularis. The epidemiology of HAE in Xinjiang has now been investigated by the analysis of data collected from the medical records of 157 clinical cases who had attended the four main hospitals in the region. These data indicate that the disease is relatively common in the Altai, western Junggar, and Tianshan mountain ranges, whereas the Tarim and Junggar basins are likely to be of low endemicity. The prevalence of the disease in the Kunlun mountains is not clear. Semi-nomadic groups, especially those of Kazakh or Mongol origin, have a higher risk of infection than other ethnic groups. Prevalence of the disease in humans appears to be correlated with aspects of the local climate, such as annual precipitation and temperature. Red foxes, Microtinae, Ochotona spp. and Marmota spp. may be important hosts of E. multilocularis in the XUAR, sustaining the transmission cycles of the parasite.

[Retrospective study of 45 cases of congenital syphilis in French Guiana from 1980 to 1990]. / Etude rétrospective de quarante-cinq cas de syphilis congenitale en Guyane française de 1980 à 1990.

From 1980 through 1990, 45 cases of congenital syphilis, i.e., 15.5/10,000 births, were reported in French Guyana. Epidemiological and clinical characteristics of these cases were analyzed retrospectively. Most mothers were immigrants (32%) or members of the traditional Maroni community (60%). Congenital infections were often severe (symptomatic in 85% of cases and fatal in 33%). Treatment should be especially aggressive in patients infected with the human immunodeficiency virus.

[HIV infection caused by maternal transmission in children born in French Guyana. Apropos of 15 cases]. / L'infection à HIV par transmission maternelle chez l'enfant né en Guyane française. A propos de 15 observations.

From 1980 to 1987, 15 children infected by HIV were born in Guyana from seropositive Haitian mothers. All these children presented the classical picture of HIV infection associated with a chronic extensive prurigo (7/15). There were 8 AIDS and 7 ARC cases. Five infants (4 AIDS, 1 ARC) died during the first year of life. There were 2 different clinical forms: 1) a severe form with cryptosporidium diarrhea and severe neurologic disturbance (one infant who died from neonatal AIDS at 3 months of age); 2) a prolonged form lasting several years complicated with infections, mainly localised to the lung.

Purification of the 2-oxoglutarate dehydrogenase and pyruvate dehydrogenase complexes of Neurospora crassa mitochondria.

A simple purification procedure for the 2-oxoglutarate dehydrogenase and the pyruvate dehydrogenase complexes of Neurospora crassa mitochondria is described. After fractionated precipitations with polyethylene glycol, elimination of thiol proteins, and gel-filtration chromatography, the resulting preparations contained both activities. Covalent chromatography on thiol-activated Sepharose CL-4B allowed the specific binding of the 2-oxoglutarate dehydrogenase complex activity in the presence of 2-oxoglutarate, whereas the pyruvate dehydrogenase complex activity was retained in the presence of pyruvate. The purified 2-oxoglutarate dehydrogenase complex showed 4 protein bands by electrophoresis under dissociating conditions with apparent molecular weights of 160,000, 56,200, 55,600, 52,600 and a Km value of 3.8 X 10(-4) M for 2-oxoglutarate. The purified pyruvate dehydrogenase complex showed 5 protein bands with apparent molecular weights of 160,000, 57,600, 55,600, 52,500 and 37,100 and a Km value of 3.2 X 10(-4) M for pyruvate.

[Intermediate hosts of Echinococcus multilocularis in northeastern France. Description of lesions found in 3 naturally infested rodent species]. / Contribution à la connaissance des hôtes intermédiaires d'Echinococcus multilocularis dans le Nord-Est de la France. Description des lésions trouvées chez 3 espèces de rongeurs naturellement infectés.

The authors describe lesions of Echinococcus multilocularis larvae found in one of 476 Clethrionomys glareolus and one of 16 Arvicola terrestris examined from Lorraine and in four Microtus arvalis from Jura. The receptivity of each of these host-species is discussed.