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Biomedical subjects

J Julvez

Publications and source records attributed to J Julvez.

At least 19 recordsLinked to original sources

[Graft safety and need satisfaction: searching for a crucial balance].

In 1998, 3,033 organs were transplanted and 3,186 stem cell and 4,053 cornea grafts were performed in France. Organ shortage varies for each organ but is particularly critical for kidneys. Given the physiological and therapeutic efficacy of grafting, an increase in organ procurement is likely to raise safety problems. This paper concerns donor-transmitted infections, mainly viral infections. Regulations on health risks express a social and cultural refusal to accept any hazard. This collective concern is however in opposition with the interests of individual patients who are likely to accept a greater risk for an obvious benefit. Although the assessment of the risk/benefit ratio is clearly different between organ and tissue transplantation, further thought needs to be given to the problem of acceptance of infectious risk in organ transplantation. In France, special exceptions are now legally authorized for specific situations. Infectious agents transmitted by grafting have not been largely reported, mainly because screening tests were not available. The number of transmitted infections is increasing with the expansion of transport facilities and with the various geographical origins of the population. In some cases, search for histocompatibility between relatives living in endemic areas introduces new risks, for example tropical diseases. Diagnosis is often made by serological or molecular biological tests which may be difficult to analyze depending on their specificity. Organ transplantation is often an emergency requiring rapid decision making, for the donor or the recipient. However, with a quality assurance process based on accepted guidelines, the appropriate answers to operational problems can be given rapidly. Patient satisfaction can be achieved only if the public health challenge is met. Increasing organ procurement can clearly be expected to be beneficial, but at the cost of higher risks. Nevertheless, benefit and risk are quite different, benefit is for the time being while risk is delayed and may be uncertain depending on individual survival. Because of the variability of human disease, especially in situations where an ultimate therapy is involved, automatic application of a standard procedure must be avoided as it would inevitable lead to a cut-back in organ procurement in an attempt to achieve a theoretically safe situation which would be contrary to individual patient's self-interest. Health care workers should have good knowledge of the epidemiology of these diseases in order to assess risk. The patient must be able to express informed consent.

France↗

[Risk and risk management connected with xenograft].

Transmission of an animal virus to man is probably a constant reality. Pathogenicity is is not inevitable. Some vaccines were contaminated by cell culture but remain safe. Haemorrhagic fevers, despite limited outbreaks, are often cited in the media. On the other hand, the influenza A virus has been responsible for a large mortality. The cases of human infection with simian viruses (herpes virus B, cytomegalovirus, spumavirus, immunodeficiency virus) were accidental and have always remained asymptomatic. Monkeypox virus emerges in only some outbreaks. No transmission of animal endogenous retrovirus has been described. The precautionary principle, in the face of an unquantifiable risk, supposes that preventive measures should be taken in advance to reduce the risk at each step: isolation of the animal source after hysterotomy, transport in a germ-free environment, procurement and transplantation in rigorous surgical conditions, long-term follow-up surveillance of the patient, his or her family and healthcare workers. All the phases of the xenotransplantation procedure should be taken to limit the number of places and persons coming into contact with the recipient. Surveillance means regular clinical information. Various samples should be taken from the animal source, recipient, his or her family contacts, medical staff and cryogenically preserved as 'biological memory'. A National Xenotransplantation Register should be set up to gather and share all information on incidents.

Animals↗

["Population and xenograft" investigation. Preliminary results].

The chronic shortage of human organs is the argument for xenotransplantation. In emergencies, acceptability is closely linked to the benefit. Little information is available on attitudes towards xenotransplantation. A poll of the attitudes was carried out, based on a questionnaire with targeted questions and background information. The goal of the study was to have a better understanding of people's attitudes towards xenotransplantation and to know the eventual changes in the answers after having been given information. For 75% of the sample, xenotransplantation would be a future biotechnology. The animal sources that would be considered for xenotransplantation were the pig and monkey. A period of ten years or more is necessary for 69% of the respondents before xenografts are performed routinely; for 19%, five years or less are needed. Human organ donation should be continued, according to 90% of the sample. Roughly, 46.4% support xenotransplantation, though in the case of a life-or-death situation acceptance reaches 65.7%. This level is higher (77%) for relatives or unknown people (71%); 74% of respondents were in favour of using normal animals and a large majority (88%) support research on xenotransplantation. A good level of confidence in medical biotechnology research and practice is suggested by this study, contrary to the results of a European survey on biotechnology.

Adult↗

Microbiological hazards of xenotransplantation. 1. Doubts and convictions relating to the risk of xenozoonosis.

The use of a xenogenic organ, tissue or cells for transplantation permits in theory the transmission of microbiological agents from one species to another. The risk of transmission of an unknown animal pathogen to man is assumed to be a public health issue. The genotype homology between human beings and non-human primates, theoretically, should increase the probability of transmission of microbiological agents. It is also assumed that pathogenicity is intensified in closely related species. Historically, most zoonoses come from species that are distant from man. Viruses are more often responsible for human disease than other animal microbial agents. Exposure of humans to animal viruses does not predicate infection. The pathogenicity of an animal virus for man may be immediate or delayed by a possible recombination of adaptive processes. The ultimate risk is the inter-human transmission of a highly pathogenic and fatal animal disease. The retrovirus possesses the enzyme which enables it to become inserted into chromosomal DNA. With an endogenous retrovirus, viral genomes are transmitted through heredity. Some of the retrovirally derived sequences in mammals are fossil viruses. It has been argued that the more closely the species are related, the less likely the retrovirus is to be transmitted, because of xenotropism.

Animals↗

Microbiological hazards of xenotransplantation. 2. Facing the risk.

The high number of xenotransplantations that have been carried out around the world since the beginning of the century, combined with the quantity of animal experiments that have exposed man to animal viruses under similar conditions, should be measured against the low incidence of known pathological consequences. The pathogenic potential of animal viruses for man, then, is unpredictable; and while the risk is acknowledged, it cannot be defined. Unless no benefit can be in xenotransplantation, the application of the precautionary principle to the extent of a moratorium seems to be excessive. The precautionary principle offers possible modes of action in the face of an unquantifiable risk. In the event of xenotransplantation, precautionary measures should be taken in advance, in order to limit risk to the maximum extent. The risk is reduced and the benefit/risk ratio becomes higher, rendering the challenge acceptable. Preventive measures should be taken as the knowledge grows about possible modes of transmission. Guidelines of good practice should be implemented at each step of the xenotransplantation process: birth of animal source by hysterotomy in a 'Specific Pathogen-Free' (SPF) centre rearing in incubator then in isolated conditions (SPF centre) transportation to and rearing in the procurement site (SPF hospital special wing) surgical procurement and xenotransplantation (hospital) post-surgical reanimation (intensive care unit) convalescence (isolated room--hospital) long-term recipient follow-up (home) All these steps should be taken in such a way as to limit the number of persons coming into contact with the recipient.

Animal Husbandry↗

Summary of principles of good practice for the production of pigs used for xenotransplantation. A report of the expert committee on xenotransplantation. Groupe d'Experts Xénogreffes.

The choice and selection of pigs used as donors of organs or tissues are founded on the concept of quality assurance of the animals included in the original herd. The rearing conditions in this herd have to guarantee a defined health status. All the stages of production, rearing, slaughter and collection of organs or tissues used for xenotransplantation or xenograft have to be fully controlled in regard to health.

Animal Husbandry↗

[Sale of chloroquine in the street in Niamey (Niger)].

Self-treatment of malaria with chloroquine is extremely common in West Africa for the febrile attacks self-diagnosed as a presumed malaria case. A survey was conducted for one year in Niamey to assess the importance of the self-treatment practice. Transmission of malaria is permanent along the river banks and seasonal in some suburbs. Chloroquine is made available by local ambulatory sellers. A sample of 199 persons purchase on average four tablets each which is less than the curative dose recommended by WHO. Self-medication is an adequate practice for reaching the primary goal of malaria strategy in sub-Saharan Africa, i.e. to reduce morbidity and mortality through prompt therapy. Developing this practice is a top public health priority. Even if the dose is not appropriate, self-medication protects against serious attacks without preventing immunization and does not seem to induce greater risk of extension of chloroquine-resistance.

Chloroquine↗

[Epidemiological stratification of malaria in the Comoro archipelago].

In the Comoros Islands, the level of malarial endemicity varies greatly from one island to the other, even though the total area (4 islands) covers less than 2,300 km2 and has a population of some 600,000 people only. The epidemiological stratification is based on the diversity of human and physical characterisation. They both determine the presence and the behaviour as well as the size of the vector's populations. Vectorial dynamics can explain varying levels of endemicity given parasitological indicators and specific morbidity. Analyzing these criteria shows up different epidemiological features and serves as a basic guideline for malaria control. The efficiency of this control depends on the relationships between the intensity and the length of the transmission, in the framework of protection mechanisms; it is of crucial importance for clinical treatment. Further elements are the age of the patient, the season and the geographic situation of the area. Stratification provides explanations for these relationships and helps to define antimalarial programmes adapting to each situation a range of therapeutic and antivectorial methods. The availability and accessibility of anti-malarial medicine is the minimum requirement for reducing mortality: domestic spray insecticides for reducing transmission are effective for several years and should be followed by the use of mosquito nets or curtains impregnated with pyrethrinoids, and in the particular case of Grande Comore, the use of larvivorous fish. As anywhere else, the economic development, which is dependent on political stability, is the essential basis for malaria control.

Age Factors↗

[Intestinal parasitic diseases in an urban environment in Sahel. A study in a district of Niamey, Niger].

Health and environment in Niamey, a capital in Sahel, are particularly linked owing to population growth, promiscuity and large pollution induced by human and animal excreta. One district, located in the centre of the town, was surveyed for drinking water quality (ammoniac and bacterial count) and use, as well as for the prevalence of parasites through both a random sample (fixed tools with methiolate-iodine-formaldehyde) and a systematic one (scotch-test). Water consumption was 16.5 litres/day/man from fresh water supplies (87%) and private wells (13%). Ammoniac measures were low in the wells but high in running water (pool and river). It was the same for faecal coliform bacteria. These results give evidence of biotope faecal pollution. The random sample (322 persons, male/female sex ratio 0,85, average age 20,6 years) showed a 42.1% parasitic prevalence. Amoeba was the most frequent parasite (53.6%); and Giardia (14.9%) was the most frequent pathogenic parasite. In the second sample (161 children under 10 years), 24.2% were carriers of oxyuris. This large intestinal parasitism, without any change in connection with previous data in Niger, points to an important fecal contamination of the people more by the way of "dirty hands" than consumption of drinking water. The parasites observed have a short biological cycle, not necessitating long-term maturation in the environment. Those whose ova or larvae must complete their cycle outside have no possibility of surviving in Sahel, thanks to the beneficial effect of sunlight (heat and ultraviolet light). The inhabitants of this district seem to have adapted to intestinal parasitism. But the occurrence of malnutrition linked to a new drought could lead rapidly to a very serious adverse result.

Adaptation, Physiological↗

[Human diseases transmitted by Culicidae in southwest Indian Ocean islands].

South-West Indian Ocean islands were inhabited at the beginning and free from all kind of vector. In Madagascar, Mayotte, Moheli and Anjouan, malaria vectors were carried by the first settlements. According to epidemics, the anopheles arrived in 1867 in Mauritius, 1869 in La Reunion and 1920 in Grande Comore. Rodrigues, Saint-Brandon and the Seychelles are still free from malaria vectors in the coastal part of Madagascarcar and in Comores archipelago, malaria is stable with a permanent transmission. Unstable malaria is seasonaly transmitted in the high territories of Madagascar; it was the same in Mauritius and Reunion island before the eradication campaign. Lymphatic filariasis is quoted in Madagascar, but Comores archipelago is an area with high transmission. The incidence of the disease is moderate in La Reunion and Mauritius and very low in Chagos and Seychelles archipelagos. There is no transmission in Rodrigues and St Brandon. Epidemics of dengue were described during the second part of the XIXth century in Mauritius and La Reunion, then in 1943 in Mayotte. But the disease was controlled in the fifties by the antimalaria campaign. A new epidemy appeared in Seychelles by the end of 1976 and then in Reunion and Mauritius next year. An isolated outbreak was described in Grande Comore only in 1994.

Animals↗

Evolution of malaria in Africa for the past 40 years: impact of climatic and human factors.

Different malarial situations in Africa within the past 40 years are discussed in order to evaluate the impact of climatic and human factors on the disease. North of the equator, more droughts and lower rainfall have been recorded since 1972; and in eastern and southern Africa, there have been alternating dry and wet periods in relation to El Niño. Since 1955, the increase in human population from 125 to 450 million has resulted in both expansion of land cultivation and urbanization. In stable malaria areas of West and Central Africa and on the Madagascar coasts, the endemic situation has not changed since 1955. However, in unstable malaria areas such as the highlands and Sahel significant changes have occurred. In Madagascar, cessation of malaria control programs resulted in the deadly epidemic of 1987-88. The same situation was observed in Swaziland in 1984-85. In Uganda, malaria incidence has increased more than 30 times in the highlands (1,500-1,800 m), but its altitudinal limit has not overcome that of the beginning of the century. Cultivation of valley bottoms and extension of settlements are in large part responsible for this increase, along with abnormally heavy rainfall that favored the severe epidemic of 1994. A similar increase in malaria was observed in neighboring highlands of Rwanda and Burundi, and epidemics have been recorded in Ethiopia since 1958. In contrast, in the Sahel (Niayes region, Senegal), stricken by droughts since 1972, endemic malaria decreased drastically after the disappearance of the main vector, Anopheles funestus, due to the destruction of its larval sites by cultivation. Even during the very wet year of 1995. An funestus did not reinvade the region and malaria did not increase. The same situation was observed in the Sahelian zone of Niger. Therefore, the temperature increase of 0.5 degree C during the last 2 decades cannot be incriminated as a major cause for these malaria changes, which are mainly due to the combination of climatic, human, and operational factors.

Africa South of the Sahara↗

[Serologic studies of non-venereal treponematoses in infants in Niamey, Niger].

Though no longer reported by health centers, non-venereal treponematoses is still endemic in both arid (Bejel) and Sahelo-soudanian (Pian) areas of Niger. This study describes randomized TPHA testing carried out among children under 5 years of age living in three different sections of Niamey. Clinical examination was not performed before testing. In the overall sample of 183 children, the percent of positive tests was 12.0% with no difference according to place of residence or age. Only 3 of 37 children under the age of 12 months were seropositive Relative levels were too high to be dismissed as serological artifacts. The most likely explanation for the high antitreponemic antibodies is endemic syphilis, or Bejel, which is increasing in this region. Results in children under the age of 12 months suggest that congenital syphilis is uncommon.

Child, Preschool↗

[The anopheles of Niger].

Nineteen species of Anopheles have been observed in the Republic of Niger but only Anopheles gambiae, An. arabiensis and An. funestus are of epidemiological importance as malaria vectors. The two species of the An. gambiae complex have the same breeding sites. But in a large part of the country they disappear all during the dry season because of the lack of adequate pools of water. Their survival is as yet an unexplained phenomenon. The most northern wet season distribution of An. gambiae complex, depending on the latitude of the intertropical front. An. funestus was no longer found after 1970 because its breeding places were destroyed both by dryness and human activity. The Republic of Niger is a border area between the palearctic Mediterranean biogeographical region and the Afrotropical one. Two different vectorial systems of malaria transmission are separated by the Sahara desert. The risk of importation of an African vector such as An. gambiae and a parasite such as Plasmodium falciparum must be considered. For the time being, the low volume of road traffic limits the risk but the construction of a paved Transsaharian highway with new human settlements and developing cultivated areas with irrigation increases the dangers of epidemic outbreaks in these oases.

Animals↗

[Grafts: what safety for what risks?].

Grafting is a rather complex technology with various indications such as end-stage organ failure or simple tissue repair. From graft procurement to transplantation, numerous risks are connected step by step from the careful surgical indication, the donor and the recipient selection, to the graft preservation, processing and implantation. The whole procedure needs a real risk management. Preventive measures cannot eliminate all risks. Clinical surveillance is necessary to prevent the transmission of opportunistic infections and the delayed effects of the immunosuppressive medication. The concept of risk/benefit is a basic public health approach in organ transplantation. The medical team needs relevant epidemiological data to balance risk and benefit. The recipient requires to be able to give a comprehensive consent. The goal is clear: the risk must decrease and the benefit must raise up and concern more people. The acceptance of a risk/benefit challenge supposes an epidemiological surveillance system; all the data about adverse events must be collected for a comprehensive epidemiological analysis. On the contrary, in tissue transplantation, safety must be maximum because, in most of the cases, the treatment permits only to improve the quality of life. In terms of research, according to the organ shortage, potential ways raise up such as medical devices or xenotransplantation. But xenotransplantation carries out some other doubts, ethical, philosophical and medical.

Forecasting↗

[Visceral leishmaniasis in Niger: six new parasitologically confirmed cases].

From January 1992 to January 1995, six cases of Kala-azar have been observed in young soldiers at Niamey, Niger. All the patients had spent some time at Tin-Galene, in Aïr mountains, Northern Niger where they had been apparently contaminated. One patient was also infected with Salmonella and an other with Mycobacterium, but none of the six was positive for HIV. The 6 cases have been confirmed by the presence of Leishmania in the sternum bone-marrow. Four patients recovered after a treatment with Glucantime; two died because the treatment was too late. In Niger, Kala-azar prevalence is probably much higher than estimated previously. So far all the cases described or suspected were in the Saharan mountains of Aïr. The strains have not been typed and it is not possible to state if it is L. infantum or L. donovani. The vector of the two species Ph. orientalis and Ph. alexandri are known to occur in the area.

Adult↗