Comparison of cardiac output measured by oesophageal Doppler ultrasonography or pulse pressure contour wave analysis.

BACKGROUND: Maintaining adequate organ perfusion during high-risk surgery requires continuous monitoring of cardiac output to optimise haemodynamics. Oesophageal Doppler Cardiac Output monitoring (DCO) is commonly used in this context, but has some limitations. Recently, the cardiac output estimated by pulse pressure analysis- (PPCO) was developed. This study evaluated the agreement of cardiac output variations estimated with 9 non-commercial algorithms of PPCO compared with those obtained with DCO. METHODS: High-risk patients undergoing neurosurgery were monitored with invasive blood pressure and DCO. For each patient, 9 PPCO algorithms and DCO were recorded before and at the peak effect for every haemodynamic challenge. RESULTS: Sixty-two subjects were enrolled; 284 events were recorded, including 134 volume expansions and 150 vasopressor boluses. Among the 9 algorithms tested, the Liljestrand-Zander model led to the smallest bias (0.03 litre min(-1) [-1.31, +1.38] (0.21 litre min(-1) [-1.13; 1.54] after volume expansion and -0.13 litre min(-1) [-1.41, 1.15] after vasopressor use). The corresponding percentage of the concordance was 91% (86% after volume expansion and 94% after vasopressor use). The other algorithms, especially those using the Winkessel concept and the area under the pressure wave, were profoundly affected by the vasopressor. CONCLUSIONS: Among the 9 PPCO algorithms examined, the Liljestrand-Zander model demonstrated the least bias and best limits of agreement, especially after vasopressor use. Using this particular algorithm in association with DCO calibration could represent a valuable option for continuous cardiac output monitoring of high risk patients. CLINICAL TRIAL REGISTRATION: Comité d'éthique de la Société de Réanimation de Langue Française No. 11-356.

Protection against Plasmodium falciparum malaria in chimpanzees by immunization with the conserved pre-erythrocytic liver-stage antigen 3.

In humans, sterile immunity against malaria can be consistently induced through exposure to the bites of thousands of irradiated infected mosquitoes. The same level of protection has yet to be achieved using subunit vaccines. Recent studies have indicated an essential function for intrahepatic parasites, the stage after the mosquito bite, and thus for antigens expressed during this stage. We report here the identification of liver-stage antigen 3, which is expressed both in the mosquito and liver-stage parasites. This Plasmodium falciparum 200-kilodalton protein is highly conserved, and showed promising antigenic and immunogenic properties. In chimpanzees (Pan troglodytes), the primates most closely related to humans and that share a similar susceptibility to P. falciparum liver-stage infection, immunization with LSA-3 induced protection against successive heterologous challenges with large numbers of P. falciparum sporozoites.

Tobacco rattle virus mediates gene silencing in a plant parasitic root-knot nematode.

Root-knot nematodes (RKNs) are sedentary biotrophic parasites that induce the differentiation of root cells into feeding cells that provide the nematodes with the nutrients necessary for their development. The development of new control methods against RKNs relies greatly on the functional analysis of genes that are crucial for the development of the pathogen or the success of parasitism. In the absence of genetic transformation, RNA interference (RNAi) allows for phenotype analysis of nematode development and nematode establishment in its host after sequence-specific knock-down of the targeted genes. Strategies used to induce RNAi in RKNs are so far restricted to small-scale analyses. In the search for a new RNAi strategy amenable to large-scale screenings the possibility of using RNA viruses to produce the RNAi triggers in plants was tested. Tobacco rattle virus (TRV) was tested as a means to introduce double-stranded RNA (dsRNA) triggers into the feeding cells and to mediate RKN gene silencing. It was demonstrated that virus-inoculated plants can produce dsRNA and siRNA silencing triggers for delivery to the feeding nematodes. Interestingly, the knock-down of the targeted genes was observed in the progeny of the feeding nematodes, suggesting that continuous ingestion of dsRNA triggers could be used for the functional analysis of genes involved in early development. However, the heterogeneity in RNAi efficiency between TRV-inoculated plants appears as a limitation to the use of TRV-mediated silencing for the high-throughput functional analysis of the targeted nematode genes.

Corticotropin-releasing hormone in chimpanzee and gorilla pregnancies.

In humans, the length of gestation and the onset of parturition have been linked to the exponential production of placental CRH and a late gestational decline in maternal plasma CRH-binding protein (CRH-BP). CRH has been shown to have direct effects on the myometrium and on the fetal adrenal, where it stimulates production of the estrogen precursor dihydroepiandrosterone sulfate. In vitro placental CRH production is stimulated by cortisol and inhibited by progesterone. To determine whether this mechanism might operate in other apes, we sampled eight chimpanzees and two gorillas through their pregnancies for CRH, CRH-BP, cortisol, estradiol, progesterone, and alpha-fetoprotein. We show that both chimpanzee and gorilla maternal plasma CRH concentrations rise exponentially as observed in the human. The gorillas exhibited a human-like antepartum fall in CRH-BP, whereas CRH-BP in the chimpanzee remained stable. Pregnancy-associated changes in cortisol, estradiol, progesterone, and alpha-fetoprotein were qualitatively similar to those observed in humans. Maternal plasma cortisol correlated with plasma CRH in both gorillas (r = 0.60; P < 0.05) and chimpanzees (r = 0.36; P < 0.02). Further, there was a strong correlation between plasma estradiol and the log of plasma CRH in the gorilla (r = 0.93; P < 0.0001) and in the chimpanzee (r = 0.72; P < 0.001), which is consistent with the hypothesis that placental CRH determines the placental production of estradiol by stimulating the production of fetal adrenal dehydroepiandrosterone sulfate. Plasma CRH and progesterone were positively correlated providing no in vivo support for progesterone inhibition of CRH release.

Phylogenetic analysis of SIV and STLV type I in mandrills (Mandrillus sphinx): indications that intracolony transmissions are predominantly the result of male-to-male aggressive contacts.

Natural SIVmnd and STLVmnd infections of mandrills in a colony at the Centre International de Recherches Médicales de Franceville (CIRMF) in Gabon were investigated by genetic analysis to determine the extent of intracolony transmission. SIVmnd pol sequence analysis indicates that the six strains present in the colony belong to the SIVmnd lentivirus subgroup previously defined according to the only available prototype sequence (SIVmndGB1), which originated from the same colony. The intraanimal nucleotide diversity (1.1-3.1%) was similar in range to that reported in individuals infected by other HIV/SIVs. The interanimal diversity (0.5-4.3%) was not significantly different from that observed in each individual mandrill, indicating an epidemiological link among the SIVmnd isolates of distinct animals within the colony. Phylogenetic analysis of these isolates, together with seroepidemiological and behavior surveillance within the colony, indicates a predominant male-to-male transmission of SIVmnd that probably occurred during bouts of interanimal aggression. Moreover, our results suggest one case of vertical transmission of SIVmnd from a naturally infected founder female to one of her six offspring. The first genetic analysis of STLV isolates from mandrills is also reported here. Partial tax/rex sequences were used to evaluate the diversity between seven STLVmnd isolates and their phylogenetic relationships with other known strains of human and nonhuman primate T cell leukemia virus, types I and II (PTLV-I/II). They all belong to the PTLV-I subtype, but two genetically distinct STLVmnd groups were evidenced within the mandrill colony. The phylogenetic analyses of the STLVmnd isolates, together with seroepidemiological and behavior surveillance of the mandrills, indicate that intracolony transmissions of STLVmnd are also predominantly the result of male-to-male aggressive contacts.

Characterization and titration of an HIV type 1 subtype E chimpanzee challenge stock.

A subtype E human immunodeficiency virus type 1 (HIV-1) isolate from the Central African Republic (E/90CR402) was adapted to growth on chimpanzee peripheral blood mononuclear cells (PBMCs) by cocultivation of irradiated, infected human PBMCs with chimpanzee PBMCs. The resulting virus was passaged in chimpanzee PBMCs to generate a stock of chimpanzee-adapted virus. Although its V3 region sequence was identical to that of the parental isolate, the chimpanzee-adapted virus had a syncytium-inducing phenotype as opposed to the non-syncytium-inducing phenotype of the parental virus. After demonstrating in one animal each that the passaged virus could infect chimpanzees following intravenous (i.v.) or cervical inoculation, the i.v. infectious titer of the stock was determined. Exposure of three chimpanzees to different doses of the virus indicated that the titer was between 2 and 5 TCID50. Thus, the HIV-1 E/90CR402 chimpanzee challenge stock established persistent infections in chimpanzees by both the i.v. and genital routes and should be valuable for future HIV-1 vaccine studies to evaluate cross-protection between HIV-1 subtypes.

Leptospirosis and Ebola virus infection in five gold-panning villages in northeastern Gabon.

An exhaustive epidemiologic and serologic survey was carried out in five gold-panning villages situated in northeastern Gabon to estimate the degree of exposure of to leptospirosis and Ebola virus. The seroprevalence was 15.7% for leptospirosis and 10.2% for Ebola virus. Sixty years after the last seroepidemiologic survey of leptospirosis in Gabon, this study demonstrates the persistence of this infection among the endemic population and the need to consider it as a potential cause of hemorrhagic fever in Gabon. There was no significant statistical correlation between the serologic status of populations exposed to both infectious agents, indicating the lack of common risk factors for these diseases.

Present challenges to risk governance.

The purpose of this short paper is to present the main challenges to risk governance in the today democratic context. The first part describes briefly the main characteristics of the approach to collective decision-making grounded on the scientific rationality, dominant in Europe for about two centuries. The second part describes the current difficulties encountered by the traditional decision-making processes when confronted with complex situations in area such as risk management but also in the management of other collective issues such as unemployment or urban violence. This description is notably based on the conclusions of the TRUSTNET European concerted action on risk governance issued in 2000. From the interdisciplinary analysis of some 11 detailed case studies of diversified risk governance contexts, the concerted action conclusions propose a model of the existing patterns of risk governance. The emergence of new co-operative processes of decision-making (Mutual Trust Paradigm) is reported in contexts where the traditional approach of collective decision-making are meeting difficulties. The third part of the paper describes the profound changes required by the adoption of co-operative decision-making processes and the main conditions for their development in the future.

Chernobyl post-accident management: the ETHOS project.

ETHOS is a pilot research project supported by the radiation protection research program of the European Commission (DG XII). The project provides an alternative approach to the rehabilitation of living conditions in the contaminated territories of the CIS in the post-accident context of Chernobyl. Initiated at the beginning of 1996, this 3-y project is currently being implemented in the Republic of Belarus. The ETHOS project involves an interdisciplinary team of European researchers from the following institutions: the Centre d'etude sur l'Evaluation de la Protection dans le domaine Nucleaire CEPN (radiological protection, economics), the Institute National d'Agronomie de Paris-Grignon INAPG (agronomy, nature & life management), the Compiegne University of Technology (technological and industrial safety, social trust), and the Mutadis Research Group (sociology, social risk management), which is in charge of the scientific co-ordination of the project. The Belarussian partners in the ETHOS project include the Ministry of Emergencies of Belarus as well as the various local authorities involved with the implementation site. The ETHOS project relies on a strong involvement of the local population in the rehabilitation process. Its main goal is to create conditions for the inhabitants of the contaminated territories to reconstruct their overall quality of life. This reconstruction deals with all the day-to-day aspects that have been affected or threatened by the contamination. The project aims at creating a dynamic process whereby acceptable living conditions can be rebuilt. Radiological security is developed in the ETHOS project as part of a general improvement in the quality of life. The approach does not dissociate the social and the technical dimensions of post-accident management. This is so as to avoid radiological risk assessment and management being reduced purely to a problem for scientific experts, from which local people are excluded, and to take into consideration the problems of acceptability of decisions and the distrust of the population towards experts. These cannot be solved merely by a better communication strategy. This paper presents the main features of the methodological approach of the ETHOS project. It also explains how it is being implemented in the village of Olmany in the district of Stolyn (Brest region) in Belarus since March 1996, as well as its initial achievements.

Practical improvement of the radiological quality of milk produced by peasant farmers in the territories of Belarus contaminated by the Chernobyl accident. The ETHOS project.

The Chernobyl post-accident situation has highlighted how the sudden emergence of persistent radioactive contamination in the environment is severely affecting the quality of life of the inhabitants in the concerned territories. The management of this situation is complex, mainly conditioned by the ability of the inhabitants themselves to be directly involved in the process of improving their living conditions. In this process, quality of life cannot be restricted solely to the dimension of radiological risk, but needs to encompass the diverse aspects of daily living, including the social, psychological, economic, political and ethical aspects. This paper presents the experience of the involvement of a group of peasant farmers from a village in the Republic of Belarus, in the process of improving the radiological quality of privately produced milk. This experience took place in the context of the ETHOS project, funded by the radiation protection research programme of the European Commission. The principal objective was to implement a complementary approach to the rehabilitation strategies adopted so far in the contaminated territories of the Republic of Belarus. This paper retraces the process of involvement of the inhabitants in a working group. It describes the characterisation of the situation by local actors, the opening of new possible actions to improve the radiological quality of milk at the individual level and the positive consequences at the scale of the village. The ETHOS project also illustrates how the scientific knowledge accumulated over many years since the Chernobyl accident in the field of radiation protection and radioecology can enter into local practices in the form of practical tools, which can be used by the population to produce significant improvements in the radiological situation.

[Evaluation of a simple and rapid method of Plasmodium falciparum DNA extraction using thick blood smears from Gabonese patients]. / Evaluation d'une méthode simple et rapide d'extraction de l'ADN de Plasmodium falciparum à partir de gouttes épaisses de patients gabonais.

In field-based studies, sometimes it is difficult to collect and store samples. We have evaluated a method of malaria parasite deoxyribonucleic (DNA) extraction from non-stained thick dried blood smears collected from 108 Gabonese patients. This method of DNA isolation was compared to those using phenol/chloroform. Patients parasitemia ranged from 0 to 240,000 parasites/microliter of blood. Both methods of DNA preparation gave similar results. Of the 108 slides, 57% were Plasmodium falciparum positive after PCR analysis of the MSA-2 gene and 34% were positive by microscopical examination. Thirty-six and seventy-two blood smears from patients were also tested after one and four weeks' storage respectively, at room temperature, and the parasite DNA was successfully extracted. We conclude that this simple method of collection and rapid procedure of parasite DNA isolation are adequate and convenient in the field when a large number of samples are required and in the case of repetitive samplings of patients.

[Allelic polymorphism of Plasmodium falciparum MSP-2 gene in blood samples from Gabonese children]. / Polymorphisme allélique du gène MSP-2 de Plasmodium falciparum analysé a partir d'échantillons sanguins d'enfants gabonais.

In this study we have undertaken the molecular analysis of the MSP-2 gene of R falciparum isolates collected from schoolchildren living in the village of Dienga (Gabon). Using conventional microscopy and the polymerase chain reaction, 61% of these children harboured parasites without any symptom of malaria (asymptomatic status). Children with a malaria episode were those with an axillary temperature > or = 37.5 degrees C and a parasitaemia > or =800 parasites/microl of blood. Comparisons of the allelic diversity and distribution of MSP-2 gene were carried out according to the clinical status at the time of sampling. Polymorphism of the MSP-2 gene was large in both clinical groups, both asymptomatic and symptomatic (11 identified alleles). The allele FC27/560bp (base pairs) was found significantly in clinical isolates. Prevalence of the 3D7 family was 68% and 44% in asymptomatic infections and clinical infections, respectively. Multiple P. falciparum genotypes were more predominant in clinical cases (2.96 clones/child with a malaria attack vs 2.01 clones/child with asymptomatic infections). We observed also a reduction of the complexity of infection beyond the age of 10 years. These results are discussed in regard to studies conducted in other areas in Africa.

Transcriptome analysis of root-knot nematode functions induced in the early stages of parasitism.

Root-knot nematodes of the genus Meloidogyne are obligate biotrophic parasites able to infest > 2000 plant species. The nematode effectors responsible for disease development are involved in the adaptation of the parasite to its host environment and host response modulation. Here, the differences between the transcriptomes of preparasitic exophytic second-stage juveniles (J2) and parasitic endophytic third-stage juveniles (J3) of Meloidogyne incognita were investigated. Genes up-regulated at the endophytic stage were isolated by suppression subtractive hybridization and validated by dot blots and real-time quantitative polymerase chain reaction (PCR). Up-regulation was demonstrated for genes involved in detoxification and protein degradation, for a gene encoding a putative secreted protein and for genes of unknown function. Transcripts of the glutathione S-transferase gene Mi-gsts-1 were 27 times more abundant in J3 than in J2. The observed Mi-gsts-1 expression in the oesophageal secretory glands and the results of functional analyses based on RNA interference suggest that glutathione S-transferases are secreted during parasitism and are required for completion of the nematode life cycle in its host. Secreted glutathione S-transferases may protect the parasite against reactive oxygen species or modulate the plant responses triggered by pathogen attack.

The relationship between parasitological status and humoral responses to Loa loa antigens in the Mandrillus sphinx model after immunization with irradiated L3 and infection with normal L3.

In order to identify antigens associated with protection and those associated with active infection, the humoral immune response of 6 Mandrillus sphinx immunized with 150 irradiated L3 and challenged with 100 normal L3 of Loa loa or 6 animals infected with 100 L3 were compared. The plasma of these animals was analysed by Western blot using adult, Mf and L3 antigens. Several antigens with molecular weights varying from 120 kDa to 13 kDa were recognized by the plasma of all animals. It was shown that early recognition of microfilarial antigens with molecular weights of 97, 68, 45 and 33 kDa correlated with the amicrofilaraemic state. A total of 83% of animals with circulating microfilariae had antibodies against the microfilariae 21 kDa antigen. Furthermore, the antibodies against the 21 kDa appeared 1 month before detection of microfilariae in the peripheral blood of 80% of these animals, and declined when animals became amicrofilaraemic. In contrast, when L3 antigen was used, a molecule with a relative molecular weight of 20 kDa was recognized by antibodies of the only animal which remained amicrofilaraemic for 1 year after immunization with irradiated L3. These results suggest that the microfilarial molecule of 21 kDa may be useful as a marker of Loa loa patent infection, whereas the 97, 68, 45 and 33 kDa molecules of microfilariae and the L3 molecule of 20 kDa may be associated with resistance against Loa loa.

A novel gamma 2-herpesvirus of the Rhadinovirus 2 lineage in chimpanzees.

Old World monkeys and, recently, African great apes have been shown, by serology and polymerase chain reaction (PCR), to harbor different gamma2-herpesviruses closely related to Kaposi's sarcoma-associated Herpesvirus (KSHV). Although the presence of two distinct lineages of KSHV-like rhadinoviruses, RV1 and RV2, has been revealed in Old World primates (including African green monkeys, macaques, and, recently, mandrills), viruses belonging to the RV2 genogroup have not yet been identified from great apes. Indeed, the three yet known gamma2-herpesviruses in chimpanzees (PanRHV1a/PtRV1, PanRHV1b) and gorillas (GorRHV1) belong to the RV1 group. To investigate the putative existence of a new RV2 Rhadinovirus in chimpanzees and gorillas we have used the degenerate consensus primer PCR strategy for the Herpesviral DNA polymerase gene on 40 wild-caught animals. This study led to the discovery, in common chimpanzees, of a novel gamma2-herpesvirus belonging to the RV2 genogroup, termed Pan Rhadino-herpesvirus 2 (PanRHV2). Use of specific primers and internal oligonucleotide probes demonstrated the presence of this novel gamma2-herpesvirus in three wild-caught animals. Comparison of a 1092-bp fragment of the DNA polymerase obtained from these three animals of the Pan troglodytes troglodytes subspecies, one from Gabon and the two others from Cameroon, revealed <1% of nucleotide divergence. The geographic colocalization as well as the phylogenetic "relationship" of the human and simian gamma2-herpesviruses support the model according to which herpesviruses have diversified from a common ancestor in a manner mediating cospeciation of herpesviruses with their host species. By demonstrating the existence of two distinct Rhadinovirus lineages in common chimpanzees, our finding indicates the possible existence of a novel human gamma2-herpesvirus belonging to the RV2 genogroup.

Comparative analysis of natural killer cell activity, lymphoproliferation and lymphocyte surface antigen expression in nonhuman primates housed at the CIRMF Primate Center, Gabon.

Six different species of nonhuman primates housed at the CIRMF Primate Center, cynomolgus monkeys (Macaca fascicularis), rhesus monkeys (Macaca mulatta), mandrills (Mandrillus sphinx), vervets (Cercopithecus aethiops pygerythrus), chimpanzees (Pan troglodyte) and baboons (Papio hamadryas), were evaluated for their natural killer cell activity and for the ability of their peripheral blood mononuclear cells to proliferate in response to known mitogens (concanavalin A, phytohemagglutinin and staphylococcal enterotoxin A) and to react with a panel of mouse monoclonal antibodies directed against human leukocyte surface antigens. Basic information on normal immune functions in these primates is important because of their use as experimental animal models for the study of human diseases such as acquired immunodeficiency syndrome (AIDS), hepatitis, loiasis and malaria.

Larval foraging behaviour and competition in Drosophila melanogaster.

Populations of Drosophila melanogaster derived by bidirectional selection for high (HA) and low (LA) aggregated oviposition behaviour differ significantly in the duration of the larval period and adult size because of differences in the developmental profiles for feeding rate over successive phases of larval growth. Feeding rates of HA larvae are significantly lower than those of LA larvae during the flexible period of growth which precedes attainment of critical mass for pupation. Consequently the HA larvae have a slower mean rate of development. In the fixed postcritical period of development the feeding rates of HA larvae are significantly higher than those of LA larvae. This causes a greater postcritical growth increment and larger adult flies. HA and LA larvae respond adaptively by changing the expression of components of their foraging behaviour depending on whether they are in or out of food. LA larvae exhibit a more flexible pattern of response and are also more successful competitors when food resources are limiting.

Behavioural correlates of selection for oviposition by Drosophila melanogaster females in a patchy environment.

The behaviour of females from lines selected for high (H) and low (L) aggregated oviposition was compared in an environment consisting of discrete patches of resource available for larval development. Oviposition behaviour was influenced by the conformation and by the texture of the substrate, but this does not account for the selective differences in levels of aggregation which are under genetic control. The distribution of males of both selected populations tends to be overdispersed across resource patches. This observation is consistent with male territorial behaviour. The dispersal patterns of females of the two selected populations differ significantly. H females show a contagious distribution whereas the distribution for L females is more nearly random. Differences in adult female dispersion are likely to be a significant factor contributing to aggregated oviposition. The level of aggregated oviposition affects the pattern of progeny survival when the unit of resource in each patch is small.