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Biomedical subjects

E Chungue

Publications and source records attributed to E Chungue.

At least 37 records · Page 2Linked to original sources
PubMed1991

Dengue surveillance in French Polynesia: an attempt to use the excess number of laboratory requests for confirmation of dengue diagnosis as an indicator of dengue activity.

The excess number of weekly laboratory requests for confirmation of dengue diagnosis over the expected number of requests forecasted by the modified Serfling method is proposed for the surveillance of dengue in French Polynesia, in addition to conventional methods. Retrospective analysis of the seasonal curves of dengue activity related to the number of laboratory requests is described for the years 1982-1987 where dengue type 4 was the only active flavivirus at the time when the forecast was initiated. By using past epidemic data, the probability of failing to recognize an increase in excess of requests as possibly epidemic was of 13.2% and 5.8%, respectively, when the criterion for epidemic increase was set respectively at 2 and 3 successive weeks during which the epidemic threshold is exceeded. A weekly surveillance was set up prospectively for 1988 using these criteria.

Clinical Laboratory Techniques↗
PubMed1991

Oral infection of Aedes polynesiensis by Wuchereria bancrofti by using parafilm membrane feeding.

In order to construct a cDNA library from third-stage larvae (L3) of Wuchereria bancrofti var. pacifica, the Parafilm membrane feeding method is proposed for the oral infection of Aedes polynesiensis. Heparinized blood supplemented with 5.10(-3) M ATP was put in the feeder with carbon dioxide provided as additional phagostimulant. The results of this artificial infection feeding method were compared with those obtained when mosquitoes fed directly on the forearm of a microfilaremic patient. The number of females feeding through the artificial membrane was smaller than on the patient's forearm (32.1 vs. 84.8%). The mean number of L3s obtained per female was not statistically different between the 2 feeding methods; however, the total number of L3s obtained from 100 females allowed to feed in each group was twice as high in the natural feeding method.

Aedes↗
PubMed1991

[Materno-fetal dengue. Apropos of 5 cases observed during the epidemic in Tahiti (1989)].

During the dengue 3 epidemic which occurred in French Polynesia between September 1989 and March 1990, number of cases of Dengue Haemorrhagic Fever (DHF) were reported among children and infants. Of interest, five cases of neonatal infections were recorded and involved the transmission of the virus from mother to child as the end of the pregnancy. Detailed observations on these cases are presented in this paper. Fever in mother, when delivering or just a few days before, represents the circumstances of the diagnosis. Analysis of the clinical features shows that fever and vasomotor troubles (blotches) were the dominating traits of the disease in the newborns. Also, hepatomegaly was constantly observed. Concerning the biological results, thrombopenia (platelets count: 100,000/mm3) was reported for all cases. According to these data, all cases were classified into DHF cases. Laboratory confirmation was obtained by serological investigations (antidengue IgM immunocapture ELISA and Haemagglutination Inhibition Tests) and/or virus isolation in both mother and child. Thus, virus was recovered in two newborns while IgM were detected in all infants and in four mothers. Severity of the disease was variable. However, out of five cases one fulfills the WHO definition of Dengue Shock Syndrome (DSC). Moreover, the authors discuss about the difficulties encountered to classify the cases according to WHO criteria for the grade classification of DHF.

Dengue↗
PubMed1990

Identification of dengue sequences by genomic amplification: rapid diagnosis of dengue virus serotypes in peripheral blood.

Polymerase chain reaction (PCR) was developed for the in vitro amplification of dengue virus RNA via cDNA. A fraction of the N-terminus gene of the envelope protein in the four dengue serotypes was amplified using synthetic oligonucleotide primer pairs. Amplified products were cloned and used as dengue type-specific probes in gel electrophoresis and dot-blot hybridization. We detected and characterized dengue virus serotypes in blood samples by the three-step procedure DNA-PAH consisting in cDNA priming (P), DNA amplification (A) and hybridization (H) using specific non-radiolabelled probes. Our findings showed that DNA-PAH was more rapid and sensitive in the identification of the infecting serotype than the mosquito cell cultures. Moreover, the failure of cultures to detect virus particles in sera containing few copies of viral genome or anti-dengue antibodies justified the approach of DNA-PAH to the dengue identification in clinical specimens.

Base Sequence↗
PubMed1988

Chlamydia trachomatis genital infections in Tahiti.

The rate of Chlamydia trachomatis infection was determined in three populations in Tahiti by means of a direct immunofluorescence test performed in specimens, tissue culture and detection of chlamydial antibody in serum specimens using a single-serotype indirect immunofluorescence test. Chlamydia trachomatis was recovered in 53% of 53 bar girls, 24% of 75 women attending a public maternity clinic for routine care, and 37% of 71 men attending a sexually transmitted disease clinic with acute or subacute urethritis. The presence of chlamydial antibody in a high proportion of the groups studied confirmed the high frequency of chlamydial infections (62.3%, 66.6% and 83.1% respectively). Neisseria gonorrhoeae infection was often associated with chlamydial infection in both bar girls and men with urethritis (11.4% and 18.3% respectively). With regard to clinical manifestations, 58.3% (7/12) of bar girls and 23.2% (10/43) women at the maternity clinic without clinical complaints were found to be Chlamydia trachomatis-positive. The presence of Chlamydia trachomatis in these asymptomatic persons highlights their important role in spread of this organism in Tahiti. The findings indicate that routine testing for Chlamydia trachomatis is warranted in patients attending the sexually transmitted disease and public maternity clinics in Tahiti.

Adolescent↗
PubMed1984

Ciguatoxin is a novel type of Na+ channel toxin.

Purified ciguatoxin at 0.1 to 10 ng/ml inhibits the net accumulation of neurotransmitters (gamma-aminobutyric acid and dopamine) by brain synaptosomes. This action is due to a stimulation of neurotransmitter release. The half-maximum effect of the toxin is observed at 0.62 ng/ml. The effect of ciguatoxin is completely inhibited by tetrodotoxin (K0.5 = 4 nM). Electrophysiological studies on neuroblastoma cells indicate that ciguatoxin induces a membrane depolarization which is prevented by tetrodotoxin and which is due to an action that increases Na+ permeability. Under appropriate conditions ciguatoxin creates spontaneous oscillations in the membrane polarization level and repeated action potentials. Ciguatoxin stimulates 22Na+ entry through the voltage-dependent Na+ channels of neuroblastoma cells and rat skeletal myoblasts when it is used in synergy with veratridine, batrachotoxin, pyrethroids, sea anemone, or scorpion toxins. The half-maximum effect of ciguatoxin on 22Na+ flux in the presence of veratridine occurs at a concentration of 0.5 ng/ml. Stimulation of 22Na+ flux by ciguatoxin is abolished by tetrodotoxin. These results taken together indicate that ciguatoxin belongs to a new class of toxins acting on Na+ channels.

Animals↗
PubMed1984

The use of mosquitoes (Aedes aegypti) to detect ciguatoxin in surgeon fishes (Ctenochaetus striatus).

A new animal assay to detect ciguatoxin in fishes was developed. Mosquitoes were subjected to intrathoracic injection of serial dilutions of ciguatoxin crude extracts. Toxicity of the fishes was expressed as the mosquito LD50 (g of flesh per mosquito). A significant correlation between the mosquito bioassay and the mouse bioassay performed on the same extracts was shown (r = 0.72, n = 80). We were able to detect 96% of the toxic fishes, while 91% of the fishes non-toxic in mice were also non-toxic in mosquitoes.

Aedes↗
PubMed1979

[Enzyme immunoassay for the detection and identification of dengue viruses from infected mosquitoes (author's transl)].

The authors deal with a "double sandwich" enzyme immunoassay for the detection and identification of dengue viruses 1, 2 and 4. They use ground glass-beads (7 mm diameter) coated with human heterospecific anti-dengue antibodies, to bind viruses obtained from infected mosquitoes (Toxorhynchites amboinensis). The mouse antibodies bound to the viruses coated on the beads are revealed by anti-mouse 7S immunoglobulins labelled with peroxydase. The method is practical, sensitive and confident. The standard curves obtained with each type show significant differences from one another until very high dilutions of the viral suspension. Inhibition tests by human immune antibodies and dengue antigens demonstrate the specificity of the reaction. This method is certainly applicable to others arboviruses and allows a large scale epidemiological survey.

Animals↗
PubMed1977

[Toxic complex from parrotfish].

Clinical and epidemiological observations suggested that a complex toxic molecule is involved in the parrotfish flesh (Scarus gibbus) poisoning from Gambier Islands. The fat soluble extract obtained from the muscles upon ciguatoxin preparation showed two toxic substances after fractionation by DEAE cellulose column chromatography. The major toxin is different from ciguatoxin judging by its chromatographic behaviour. The other is closely similar to (or identical with) ciguatoxin from the moray eel Gymnothorax javanicus. They were named SG1 for the new toxin and SG2 for the ciguatoxin like compound. Successive filtrations on Sephadex LH-20 of SG1 and SG2 gave respectively a lethality to mice of 0.03 microgram/g and 0.06 microgram/g. SG1, specifically occurs in the muscles of the parrotfish family (scaritoxin) while it is absent from other ciguateric fishes. According to that specificity and the lack of SG1 in S. gibbus liver and gut contents, the origin of scaritoxin is briefly discussed.

Animals↗