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Biomedical subjects

A Georges

Publications and source records attributed to A Georges.

At least 19 recordsLinked to original sources
PubMed1995

Dilution assessment of cervicovaginal secretions obtained by vaginal washing for immunological assays.

Local immunological defense mechanisms in the cervicovaginal mucosa currently remain incompletely defined, especially from a quantitative point of view. Addition of an inert substance, lithium chloride (LiCl), into the washing buffer used to carry out the vaginal washing for collecting cervicovaginal secretions and measurement of its concentration with a flame absorption spectrophotometer, before and after the specimen is sampled, permits the quantification of the volume of cervicovaginal secretions collected and the approximation of the dilution factor of a soluble component introduced by the washing. Lithium, at a concentration of 10 mM, gives the best precision of measurement and has no effect on the results of the immunoassays. In a population of 27 nonpregnant women (age range, 18 to 45 years), the volume of cervicovaginal secretions collected by vaginal washing with 3 ml of LiCl-phosphate-buffered saline was 12% +/- 3.2% (mean +/- standard deviation) of the total volume and showed large interindividual variations (range, 5.6 to 18.8%); the mean dilution factor of a soluble component from the vaginal secretions was 9.9% +/- 2.8% (range, 6.3 to 18.8%). According to the date of the menstrual cycle, the mean volume of collected cervicovaginal secretions was significantly increased in the luteal phase in comparison with the follicular phase; conversely, the mean dilution factor of a soluble component was more important in the follicular than in the luteal phase. These features strengthen the need to quantify accurately the dilution factor introduced by vaginal washing when studying cervicovaginal immunity.

Adolescent↗
PubMed1993

Diversity of V3 region sequences of human immunodeficiency viruses type 1 from the central African Republic.

Nucleotide sequences of the central portion of gp120, including the third hypervariable (V3) loop, were obtained from lymphocytes cocultivated with SupT1 cells from 29 AIDS patients in Bangui, Central African Republic. These sequences displayed significantly greater diversity (average distance, 23%) than has been previously observed in isolates from comparably restricted geographical areas. Isolates belonging to four major subtypes of HIV-1 were found; the only subtype not represented was the North American/European subtype B. Unlike the situation in Zaire and Uganda, where subtypes A and D account equally for virtually all isolates of HIV-1, the predominant subtypes in the Central African Republic, accounting for two-thirds of the isolates, were subtypes A (10 isolates) and E (9 isolates). Subtype E represents a group of variants that have previously been found only in Thailand. Only one isolate belonging to subtype D was found. Also recovered were two isolates of subtype C, a subtype associated with southern African and Indian isolates but not previously detected in central Africa. These isolates, although clearly clustering with subtype C, formed a distinct subset, differing from one another by 8.8% and from the Indian and South African subtype C isolates by an average of 22.5%. High interpatient, intrasubtype variation was also seen among the CAR subtype A (average pairwise difference, 19.3%) and subtype E (10.9%) isolates. The diversity of V3 sequences in this set has implications for immunization protocols that rely on the recognition of V3. This study underscores the necessity of basing intervention strategies on knowledge of the particular sequences present in the target population or geographical area.

Acquired Immunodeficiency Syndrome↗
PubMed1992

[Resurgence of yaws in Central African Republic. Role of the Pygmy population as a reservoir of the virus].

The authors present the results of a clinical (framboesia) and serological (TPHA and VDRL) investigation aimed at defining the reservoir of virus of yaws in the Lobaye area (southwest of CAR) out of which the disease spreads in spite of previous mass treatment campaigns. The Lobaye focus is still active because we found among the pediatric population under the age of 15 years, 5.6% contagious skin lesion and 19.6% VDRL+. In this area with contact between nomadic Pygmies and sedentary ethnic groups, the observed level of clinical and serological attacks suggested that the pygmie population, as previously described, makes up the principal focus of yaws. For every 1 case found through clinical examination, 3.5 cases VDRL+ and 4.8 cases TPHA+ are found through serological examination. This proportion indicates that clinical screening alone is not sufficient to evaluate the endemic yaws level in a population.

Adolescent↗
PubMed1992

[Epidemiology of Tinea capitis in Bangui (Central African Republic)].

In Bangui (Central African Republic) an epidemiological survey making use of cluster sampling has been performed. Prevalence rate is not very high in Bangui (3.4%). Boys are more infected than girls. Both in rural and urban area prevalence rates are decreasing with age. Microsporum langeronii has been identified in 98% of case.

Adolescent↗
PubMed1988

Atypical haplotypes linked to the beta S gene in Africa are likely to be the product of recombination.

We report here the haplotypes of 10 MstII-defined SS patients and a S/beta o thalassemia from the Central African Republic, exhibiting 7 different atypical haplotypes that are different from the typical Bantu haplotype that characterize over 93% of the beta s bearing chromosomes in that region of Africa. Of the seven atypical haplotypes, six can be easily interpreted as the result of recombination around the "hot spot" 5' of the beta gene, between a typical Bantu haplotype and other haplotypes available in the normal population. Except for one case that requires further study, this result demonstrates that the main mutational event leading to sickle hemoglobin in Bantu-speaking Africa was the mutation of the beta gene in a Bantu haplotype background.

Africa↗
PubMed1987

The hematologic characteristics of sickle cell anemia bearing the Bantu haplotype: the relationship between G gamma and HbF level.

Previous work has demonstrated that the HbS gene has appeared and expanded three times in Africa in three separate geographic locations and that these three distinct mutational events can be identified by linked DNA polymorphic sites (haplotypes) surrounding the abnormal gene. We have reported that the Senegalese and Beninian haplotypes differ in G gamma expression, mean percentage of HbF, and percentage of dense cells. We now report on the third haplotype, the Bantu, and find that it has intermediate features, namely, the high mean percentage of HbF and low percentage of dense cells associated with the Senegalese haplotype, but with a low percentage of G gamma expression similar to the Beninian haplotype. The distribution of percent HbF is quite different from Senegal haplotype-bearing sickle cell anemia patients since it covers a much wider range. The low G gamma expression is also different from the Beninians since it contains a significant and unique cluster of individuals with lower than 38% G gamma. Interestingly, among the Bantu there is a strong correlation between HbF levels and G gamma expression, which is not seen with the other haplotypes. These findings open the possibility that among the Bantu haplotype-bearing individuals two chromosomal types exist that define different levels of G gamma and HbF expression. Further structural exploration of these two potential subhaplotypes is needed.

Anemia, Sickle Cell↗
PubMed1986

[Infection of insect cell lines by the HIV virus, an agent of AIDS, and a demonstration of insects of African origin infected by this virus].

The etiological agent of AIDS known as HIV has been shown to bind on different insect cell lines including Drosophila, Mosquito, Ceratitis; and his DNA to be integrated in the cellular genome, but no expression of the viral genome was detected in those cells. None of the human lymphocytes markers is expressed at the surface of the insect cells. HIV proviral DNA has been also found in various insects from Central Africa (Zaïre and Central Africa Republic) but not similar insects from the Paris area. These data suggest that insects could be a reservoir or a vector for the AIDS virus.

Acquired Immunodeficiency Syndrome↗
PubMed1985

Pharmacological properties of the new potent diuretic torasemide in rats and dogs.

Torasemide, a pyridine-3-sulfonylurea derivative, has potent diuretic activity in rats and dogs. In both species urinary volume and electrolyte excretion increased linearly with the logarithm of the dose, thus resembling the profile of a high ceiling diuretic. The minimum effective dose by oral route was 0.2 mg/kg in the rat and less that 0.1 mg/kg in the dog. Maximal effect was obtained with about 10 mg/kg. Experiments by oral and i.v. routes in the rat indicated that torasemide was equally potent by both oral and parenteral administration. In both rats and dogs, urinary excretions induced by torasemide were similar to those obtained with furosemide. However, for the same natriuretic effect, potassium losses with torasemide were significantly less than with furosemide. On a weight basis, torasemide was 9-40 times more potent than furosemide in the rat and about 10 times in the dog. After oral administration the diuretic effects of torasemide started within 20 min and lasted approximately 2 h in the rat and more than 8 h in the dog. The activity of torasemide was not decreased after a repeated daily oral dose of 10 mg/kg for 15 days in the rat. Torasemide at a daily oral dose of 5 mg/kg for 12 days effectively reduced the arterial blood pressure in desoxycortone induced hypertension in the rat. Besides the diuretic and antihypertensive effects no other significant pharmacological effects were observed with torasemide in the different in vitro and in vivo experiments. Torasemide was practically fully absorbed by the gastrointestinal tract, its bioavailability by oral route ranged from 80 to 100%.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Renal effects of the high ceiling diuretic torasemide in rats and dogs.

The mode of action of torasemide was investigated by clearance experiments in dogs and rats. In the dog, torasemide (1 mg/kg i.v.) had no significant effect on glomerular filtration rate (GFR) but increased p-aminohippuric acid (PAH) clearance by 16% (p less than 0.01). In the rat both GFR and PAH clearance were significantly decreased, on an average 8-17%, by torasemide infused in the dose range of 1 to 20 mg/kg i.v. After i.v. injection the onset of diuresis was observed within 5 to 10 min and peak effect within 20 to 40 min in the rat and within 40 to 60 min in the dog. Fractional water and sodium excretions of nearly 25% were obtained in the rat with a dose of 8 mg/kg i.v. At equipotent doses, torasemide and furosemide induced similar diuretic and natriuretic effects in function of time in the rat. In the dog the effects lasted much longer with torasemide than with furosemide. This difference can be related to the longer half-life (about 8 h) of torasemide in the dog. In both species significant differences could be noted between torasemide and furosemide with respect to the time course of their effects on the urinary excretion of potassium. From the first experimental hour on, torasemide proved to be significantly less kaliuretic than furosemide as shown by increased Na/K ratios, during the third experimental hour they reached 20.5 vs 9.9 in the dog and 11 vs 7.5 in the rat with torasemide and furosemide, respectively. In hydropenic dogs, free water reabsorption was significantly reduced with torasemide and osmolar clearance significantly increased.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia↗
PubMed1982

Haemorrhagic fever in Gabon. I. Incidence of Lassa, Ebola and Marburg viruses in Haut-Ogooué.

A serological enquiry aimed at determining the incidence of infection with Lassa, Ebola and Marburg viruses was conducted on the human population of the region of Haut-Ogooué (Gabon) and on primates. The results, obtained by the indirect immunofluorescence technique, showed that more than 6% of the human population had had contact with Ebola virus but no antibodies against Marburg or Lassa viruses were found. Most sera reacted to an Ebola antigen from a Zairian strain, but showed little or no reaction to an antigen from a Sudanese strain.

Adult↗