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Biomedical subjects

J P Gonzalez

Publications and source records attributed to J P Gonzalez.

At least 19 recordsLinked to original sources
PubMed2003

Identification of Rickettsia spp. and Bartonella spp. in ffrom the Thai-Myanmar border.

During a survey for possible rickettsial vectors in villages of the central part of the Thai-Myanmar border from September 2001 to February 2002, four species of fleas were collected from common peridomestic animals. All fleas were tested by PCR to detect DNA of bacteria of the genera Rickettsia (gltA and ompB genes) and Bartonella (ITS and ftsZ genes). Sequencing of PCR-amplified products was done using gltA fragments for Rickettsia and ftsZ fragments for BARTONELLA: Two genotypes related to Rickettsia felis were identified in three Ctenocephalides canis and one C. felis specimen. Further, the following Bartonella spp. were detected: Bartonella henselae in two C. felis specimens; Bartonella clarridgeiae in three C. felis specimens; and a new Bartonella genotype in one Nosopsylla fasciatus specimen. Rickettsia and Bartonella may be frequently detected in fleas infesting peridomestic animals from the western border of Thailand.

Animals↗
PubMed2001

Evolution of the Old World Arenaviridae and their rodent hosts: generalized host-transfer or association by descent?

Ten scenarios optimizing the number of cospeciation events between the phylogenies of the Old World Arenaviridae (OWA) and their murine hosts are tested while attempting to answer the following questions. Does the coevolutionary model explain their respective distribution? What kind of evolutionary events could have most frequently contributed to the horizontal and/or vertical transmission of the OWA? How to define secondary hosts and to interpret their existence in the evolutionary process? Where are the geographical origins of the OWA? All scenarios support the "diffuse coevolution" hypothesis previously proposed for the OWA, in which parallel phylogeny and/or host switches on closely related hosts can be considered as the most common mechanisms of transmission. The scenarios allow defining more precisely the concepts of principal and secondary hosts. Such scenarios also suggest that the diversity of the viruses and their rodent hosts could be higher than currently expected and that cophylogeny could have been underestimated. The "diffuse coevolution" hypothesis permits to interpret the transfer of the viruses to distant hosts as a result of a disturbance in their regular mode of dispersion, which could match with the periods of emergence as human parasites. The comparison of the viral phylogeny with the host cladogram also suggests that the viruses parasitized the Murinae before several lineages became distinct and spread in Africa. This supposes that the origin of the arenaviruses has to be found out of Africa.

Animals↗
PubMed2000

Ebola and Marburg virus antibody prevalence in selected populations of the Central African Republic.

With the natural history of the filovirus family seemingly unknown, filovirus ecology in its natural environment remains a rudimentary field of research. In order to investigate the maintenance cycle of filovirus in Central Africa, a study was conducted within the rain forest of the Central African Republic. The epidemiological study determines the frequency and distribution of filovirus seroprevalence in a selected human population. Using an ELISA, serum samples from Pygmy and non-Pygmy populations were tested for Ebola-Zaire virus and Marburg (MBG) virus antibody. Filovirus antibody reacting sera were found in all zones investigated, and in all populations studied (Ebola virus IgG 5.3%; Marburg virus IgG 2.4%). Pygmies appeared to have a significantly higher seroprevalence (P < 0.03) against Ebola-Zaire virus (7.02%) than non-Pygmies (4.2%). MBG virus or related unknown filovirus strains also seem to be present in the western part of Central Africa. MBG virus antibodies were present in different Pygmy groups (ranging from 0.7 to 5.6%, mean 2.05%) and in several non-Pygmy populations (ranging from 0.0 to 3.9%, mean 3.4%) without an overall significant difference between the two groups (P = 0.14). The potentialities of nonpathogenic filovirus strains circulating in the Central African Republic are discussed.

Antibodies, Viral↗
PubMed2000

The potential role of rodents in the enzootic cycle of Rift Valley fever virus in Senegal.

Wild rodents (214) of fourteen species were trapped at seven sites in Senegal. Arvicanthis niloticus and Mastomys erythroleucus were among the most frequently collected species (77.2% of total capture). All rodents were examined for the presence of anti-Rift Valley fever virus (RVFV) antibody; the prevalence over all sampled species was 3.8%, varying widely with respect to species and location. Four of 14 species of rodents were found to have anti-RVFV antibodies: Rattus rattus (one positive of two tested) Mastomys huberti (13.5%), A. niloticus (4.3%), and M. erthroleucus (2.4%). The highest prevalence of anti-RVFV antibody was recorded within the enzootic area of the Senegal River delta, at Richard Toll (9.6%). A. niloticus and M. erythroleucus and a strain of laboratory-bred mice were experimentally inoculated with two strains of RVFV and examined for viremia, illness, seroconversion and mortality. A. niloticus and M. erythroleucus demonstrated a limited resistance to infection, thus potentially allowing for the replication of virus in these animals and making these species possible candidates as hosts in the maintenance cycle of RVFV in nature.

Animals↗
PubMed2000

Preliminary study on potential circulation of arenaviruses in the rodent population of Nakhon Pathom Province, Thailand and their medical importance in an evoluting environment.

Preliminary serological investigations were prefered to detect evidence of arenavirus infection in rodents. The study examined virus antibody in 367 rodents trapped in 6 different geographical areas of Nakhon Pathom Province, Thailand from February-March, 1998. The overall seroprevalence among rodents was 13.3%, mostly in Bandicota savilei (35.7%) and Rattus norvegicus (31.5%). Between ecology, behavior and sex of the rodents, seroprevalence was not significantly different (p>0.05), however the seroprevalence found among different geographical areas of Nakhon Pathom Province were significantly different (p<0.0001).

Animals↗
PubMed2000

Serological study of hantavirus in the rodent population of Nakhon Pathom and Nakhon Ratchasima Provinces Thailand.

A serological survey has been carried out to detect evidence of hantavirus infection in rodents from two provinces of Thailand. This study aimed to examine virus antibody in 354 rodents trapped among 6 different villages of Nakhon Pathom Province (February-March, 1998) and in 326 rodents trapped among 14 villages of Nakhon Ratchasima Province (August-October, 1998). Seroprevalence among rodents from Nakhon Pathom Province (2.3%), was mostly find in Rattus norvegicus (3.8%) and Bandicota indica (2.6%). In Nakhon Ratchasima Province seroprevalence (4.0%) was mostly in Bandicota indica (19.1%) and Rattus exulans (3.5%).

Animals↗
PubMed1999

[Experimental transmission of Crimean-Congo hemorrhagic fever virus: role of 3 vector species in the maintenance and transmission cycles in Senegal].

In this article, we published the role of three species of ticks Amblyomma variegatum (Fabricius, 1974), Hyalomma marginatum rufipes (Koch, 1844) and Hyalomma truncatum (Koch, 1844) in the maintenance and transmission of the CCHF virus. The imagos of these species were infected by intracoelomic route. Vertical transmission (transtasial and transovarial) and horizontal transmission for different stases were studied by isolation on newborn mice, polymerase chain reaction, indirect immunofluorescence and ELISA. Our results proved that 15 days after inoculation, infection rates of 100% were noted with Hyalomma marginatum rufipes and Hyalomma truncatum. This rate is about 60% for Amblyomma variegatum. The imagos of the three species infected have transmitted the virus to their host during blood feeding (100%). A high transovarial transmission for Hyalomma marginatum rufipes and Hyalomma truncatum were observed (respectively 53 and 50%). This rate is about 12% for Amblyomma variegatum. The tick infection does not persist up to the first generation for the three species studied. Ticks are temporary reservoirs vectors but not permanent reservoirs of CCHF virus.

Animals↗
PubMed1999

[Experimental transmission of Crimean-Congo hemorrhagic fever virus by Rhipicephalus evertsi evertsi (Acarina:Ixodidae)].

We have conducted experiments to assess the ability of Rhipicephalus evertsi evertsi tick to transmit the Crimean-Congo haemorrhagic fever (CCHF) and determine their reproductive cycle. The Rh. e. evertsi was infected by intracoelomic (transparietal and intra-anal) inoculation during the imaginal stases and by oral feeding on an infected viremic goat during imaginal and nymphal stases. The infection rate, transovarial and trans-stasial CCHF virus transmission were monitored for virus reisolation after suckling mice inoculation and the virus identified by ELISA and IFA for antigen detection. After intracoelomic inoculation, unfed adults had viral titers ranging from 0.67 to 2.9 log DL50/0.02 ml and had transmitted the virus to their vertebrate hosts by blood feeding. After 8 to 10 days of blood feeding duration, infection rates were respectively 36% and 100% for male and female ticks. In two instances out of seven transovarial transmission was observed and the virus reisolated from larvae of first generation. However, the virus was not detected after nymphal metamorphosis. After blood feeding on viremic goats, 71% of the nymphae were infected. After metamorphoses 22% of the males and 42% of the females had a low virus titer. Rh. e. evertsi appears to have a limited efficacy in transmitting and replicating the CCHF virus but must be not neglected as a potential vector during an epizootic manifestation.

Animals↗
PubMed1999

[An experimental model to analyse the characteristics of a strain of Culex pipiens and its sensitivity to insecticides].

This study, based on phenotype of green larvae colour, has enabled the selection of a genetically distinct line of Culex pipiens pipiens. The four loci under study were found to be homozygous to the 42nd generation. These loci were associated with an increased sensitivity to organochlorides in the progeny when compared to the parent strain. This observation, with possible expansion to other species, has potential practical applications in the identification of susceptible insect populations in insecticide campaigns.

Animals↗
PubMed1999

Augmentation of the 100 kg ISO wheelchair test dummy to accommodate higher mass: a technical note.

Most of the 22 approved or developing ISO standards rely on a wheelchair test dummy, a specialized device described in ISO 7176-11. The purpose of this study was to develop a means for modifying the design of the ISO 7176-11 test dummy to be suitable for testing with higher masses. The changes are based upon published data for obese individuals. With these data, we derived equations for determining the distribution of the additional mass among the test dummy components, and the locations of the centers of mass. The results of this study provide guidelines for adding mass to the 100 kg wheelchair test dummy to accommodate testing of wheelchairs designed for obese individuals.

Anthropometry↗
PubMed1996

Genetic characterization and phylogeny of Sabiá virus, an emergent pathogen in Brazil.

Sabiá virus, one of five arenaviruses from South America known to cause hemorrhagic fever in humans, emerged in 1990 when it was isolated from a fatal case in Sao Paulo, Brazil. Subsequently, it has caused two laboratory-acquired infections. Its natural distribution and host are still unknown. Using viral RNA and multiple polymerase chain reaction products as templates, the nucleotide sequence of the small (S) RNA segment of Sabiá virus, which codes for the nucleocapsid (N) and glycoprotein precursor, was determined. This virus shares an ambisense genome in common with other arenaviruses, although it has a unique predicted three stem--loop structure in the S RNA intergenic region. Phylogenetic analysis of a portion of the N gene sequence confirmed that Sabiá virus is distinct from all other members of the Arenaviridae and shares a progenitor with Junin, Machupo, Tacaribe, and Guanarito viruses.

Amino Acid Sequence↗
PubMed1995

Influence of vitamin C on the absorption and first pass metabolism of propranolol.

The effect of ascorbic acid on the availability of propranolol has been examined. After oral administration of propranolol 80 mg with or without ascorbic acid pretreatment (2 g), the plasma concentrations and urinary excretion of propranolol and its metabolites, 4-hydroxy-propranolol and propranolol-conjugated, were determined by HPLC. Compared to controls, vitamin C decreased the maximum concentration of propranolol from 463 to 334 nmol.l-1, and the area under the propranolol concentration-time curve (from 0 to 24 hours) from 3.13 to 1.96 mumol.l-1.h. The time to reach maximum propranolol concentration was increased from 1.9 to 2.7. The total amount of drug recovered in urine has also significantly diminished (from 12.6 to 4.29 mg). No change in elimination rate was observed, indicating that ascorbic acid had affected both the absorption process and the first pass metabolism. The heart-rate decreased less when propranolol was administered with ascorbic acid in comparison to control subjects, although this interaction has little biological importance.

Administration, Oral↗
PubMed1995

Insect densoviruses may be widespread in mosquito cell lines.

A diagnostic PCR assay was designed based on conserved regions of previously sequenced densovirus genomic DNA isolated from mosquitoes. Application of this assay to different insect cell lines resulted in a number of cases of consistent positive amplification of the predicted size fragment. Positive PCR results were subsequently confirmed to correlate with densovirus infection by both electron microscopy and indirect fluorescent antibody test. In each case the nucleotide sequence of the amplified PCR fragments showed high identity to previously reported densoviruses isolated from mosquitoes. Phylogenetic analysis based on these sequences showed that two of these isolates were examples of new densoviruses. These viruses could infect and replicate in mosquitoes when administered orally or parenterally and these infections were largely avirulent. In one virus/mosquito combination vertical transmission to progeny was observed. The frequency with which these viruses were detected would suggest that they may be quite common in insect cell lines.

Animals↗
PubMed1995

Molecular phylogeny of Guanarito virus, an emerging arenavirus affecting humans.

The nucleotide sequence of a portion of the nucleocapsid (N) gene of the Guanarito virus prototype strain (INH-95551) has been determined. It was obtained by direct RNA and polymerase chain reaction (PCR) fragment sequencing of the 3' end of the small (S) RNA fragment. A comparison of this 782-nucleotide segment was done with the known homologous gene sequences of five other arenaviruses: Junin, Machupo, Tacaribe, Pichinde, and lymphocytic choriomeningitis (LCM). Phylogenetic analysis of the N gene open reading frame showed that Guanarito virus is genetically distinct from other members of the Arenavirus family, with 32% nucleotide sequence divergence from Junin, 30% from Machupo, 32% from Tacaribe, 41% from Pichinde, and 45% from LCM. Comparison of amino acids encoded by this sequence region indicated a probable antigenic domain (amino acids 55-63) shared among all arenaviruses studied to date. Along with its host restriction and focal distribution, our data support the hypothesis that this virus has been evolving independently in its endemic focus, for some time.

Amino Acid Sequence↗
PubMed1994

[Crimean-Congo hemorrhagic fever in Senegal. Latest data on the ecology of the CCHF virus].

The authors finalize the knowledge on the ecology of the CCHF virus in Senegal, West Africa. They specify two new major data for the understanding of the viral ecology in West Africa. The recognition of a bird species, common and widely distributed in Senegal (Tockus erythrorhynchus, Coraciiformes, Bucerotidae), that replicates the virus and infects the immature stages of its current parasite Hyalomma marginatum rufipes in more than 90% of the cases, explains why the minimum infection rate of the adults of this species of tick is always very high. The implication of Rhipicephalus evertsi evertsi in the viral ecology and/or a high efficiency of the transovarial transmission of the virus in Hy. m. rufipes would help to explain the maintenance of the endemy in the sahelian area. In the sahelian zone, Hy. marginatum rufipes must play the leading part, together with Rh. e. evertsi if vector, for the maintenance of the endemy. Hy. truncatum, the adults of which can readily bite man, ensures the vectorial transmission to him. In the sudanian zone, Amblyomma variegatum must play the same part as the Hyalomma and Rh. e. evertsi (if vector), and is surely the main vector to man, giving perhaps rise to less virulent strains (non hemorrhagic ones).

Animals↗
PubMed1994

[Decrease of natural immunity against Rift Valley fever in domestic ruminants of the Senegal River basin after the epizootic outbreak of 1987].

A domestic ruminants serosurvey of Rift valley fever (RVF) neutralizing antibodies has been carried out during three years after the 1987 epidemic in the Senegal River Basin. Authors present results from the 1990 serosurvey that are matched with the preview surveys. Out of 1,225 ongulate tested, 17.2% had RVF virus antibodies. There is a global decrease in the herds immunity since the epizootic manifestation associated with the 1987 epidemic. Significant differences in seroprevalence are observed from the delta (28.5%) to the lower (17.9%) and middle valley (6.1%) of the Senegal river. Cattle are more likely to be with an higher seroprevalence than goat and sheep.

Animals↗