Електричні властивості двошарових плівок окислів металів

Досліджені газочутливі властивості тонких двошарових плівок окислів металів, в яких нижній шар є крупнокристалічним, а верхній має високодисперсну структуру. Розглядаються фізичні основи і технологічні прийоми одержання таких плівок вакуумним методом. Двошарові плівки виявляють кращу чутливість до відновлюючих домішок у повітрі, ніж одношарові

Історична регіоналістика в системі "просторової історії": диференціації предметних полів

Стаття присвячена обґрунтуваннюзавдань іфункцій історичної регіоналістики як частини "просторової історії".Окреслено її дисциплінарні межі, об’єктно-предметну сферу, проаналізовано відповідний термінологічний інструментарій.Статья посвящена обоснованию задач и функций исторической регионалистики как части "пространственной истории". Проанализированы ее дисциплинарные границы, объектно-предметная сфера, соответствующий терминологический инструментарий.The article is devoted to the substantiation of tasks and functions of historical regional studies as the part of "spatial history". Disciplinary limits of the new trend and its subject – objectivity realm are outlined as well as corresponding set of terms is examined

Prévalence et épidémiologie moléculaire du VIH-1 en Afrique centrale et de l'ouest (étude de cas en République Démocratique du Congo, au Nigeria et au Mali)

PARIS-BIUSJ-Thèses (751052125) / SudocPARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceF

Identification of a complex env subtype E HIV type 1 virus from the Democratic Republic of Congo, recombinant with A, G, H, J, K, and unknown subtypes

Up to now, all known env subtype E viruses (CRF01-AE) have had the same mosaic structure with subtype A, and no other env subtype E HIV-1 viruses with non-A subtypes in their genomes have been described. In this report, we describe the full-length genome sequence of an env subtype E isolate with a recombinant genome different from the prototype CRF01-AE strains. The 97CD-KTB-49 strain, obtained from a tuberculosis patient in Kinshasa, has a complex mosaic genome involving subtypes A, E, G, H, J, K, and several unknown fragments. The U sequences formed well-separated clusters together with previously described unknown fragments from CRF04-cpx (subtype I), and from Z321, the oldest intersubtype recombinant isolated in 1976 in the Democratic Republic of Congo. The complex recombinant virus from our study is not an isolated strain ; partial sequencing of a second strain, 97CD-KFE45, confirmed the breakpoints observed in the 97CD-KTB-49 strain in the regions sequenced. The complexity of these recombinant strains suggests a longstanding presence of subtype E in Central Africa. (Résumé d'auteur

Identification and molecular characterization of subsubtype A4 in Central Africa

Phylogenetic analysis on partial env sequences of HIV-1-positive samples obtained from sentinel population groups in HIV serosurveillance studies in 1997 and 2002 in the Democratic Republic of Congo (DRC) revealed a high genetic diversity in the number of cocirculating subtypes/CRFs as well as intrasubtype diversity. A cluster of three strains that formed a distinct and well-separated group within the subtype A radiation was observed. To determine a more precise structure of these viruses, the full-length genomes were sequenced. Phylogenetic tree and bootscan analysis showed that all three newly characterized viruses formed a new nonrecombinant lineage that was more closely related to subtype A. The SUDI (Subtype Distance) program showed that the distances of the newly derived HIV-1 sequences to subtype A references fell in the range of distances previously characterized for subsubtypes. According to current nomenclature rules, we have thus designated this new lineage as subsubtype A4. Analysis of viral sequences from other African countries suggests that the A4 strains seem restricted to DRC where they already circulated at the onset of the HIV/AIDS epidemic

Genetic subtypes of HIV type 1 and HIV type 2 strains in commercial sex workers from Bamako, Mali

In Africa the highest HIV infection rate has been reported among female commercial sex workers (CSWs) who are at increasing risk of acquiring and transmitting HIV infection. In October 1995, 176 CSWs were studied in Bamako, the capital city of Mali. The ages of the CSWs ranged from 15 to 50 years old (mean, 28.8 years). Only 20.45% of the 176 CSWs were Malian ; the majority were from Nigeria (32.9%) and Ghana (31.8%), and the remaining were from other African countries. Forty-one percent were active for less than 1 year as a commercial sex worker, and the length of prostitution for the remaining women ranged from 1 to 15 years (mean, 2.76). A total of 81 (46.02%) of the 176 CSWs were positive for HIV antibodies ; 63 (35.8%) were HIV-1 positive, 3.9% were HIV-2 posivitive, 11 (6.2%) had antibodies to HIV-1 and HIV-2, and none of them had antibodies to group O viruses. For all HIV antibody-positive samples, PBMCs were separated and genetic subtypes of HIV-1 were determined using the heteroduplex mobility assay (HMA), with ED5-ED12 as outer and ES7-ES8 as inner primers. Among the 66 HIV-1 strains characterized, 53 (80.3%) were subtype A, 2 (3.1%) belonged to subtype C, 1 (1.5%) belonged to subtype D, and 10 (15.1%) were identified as subtype G. Among the 10 subtype G strains, 8 were obtained from women who were very recent CSWs, with an activity of 1 year or less, assuming that there is a high probability that these infections occurred recently. Genetic subtypes of five HIV-2 viruses were determined by sequencing of the env and/or gag genes followed by phylogenetic analysis, and all of them belonged to subtype A. Comparison of HIV-1 and HIV-2 seroprevalence data from our study with previous data from Mali shows a significant rise in HIV-1 prevalence and a significant decrease in HIV-2 prevalence and confirms similar trends observed in neighboring countries... (D'après résumé d'auteur

Unprecedented Degree of Human Immunodeficiency Virus Type 1 (HIV-1) Group M Genetic Diversity in the Democratic Republic of Congo Suggests that the HIV-1 Pandemic Originated in Central Africa

The purpose of this study was to document the genetic diversity of human immunodeficiency virus type 1 (HIV-1) in the Democratic Republic of Congo (DRC; formerly Zaire). A total of 247 HIV-1-positive samples, collected during an epidemiologic survey conducted in 1997 in three regions (Kinshasa [the capital], Bwamanda [in the north], and Mbuyi-Maya [in the south]), were genetically characterized in the env V3-V5 region. All known subtypes were found to cocirculate, and for 6% of the samples the subtype could not be identified. Subtype A is predominant, with prevalences decreasing from north to south (69% in the north, 53% in the capital city, and 46% in the south). Subtype C, D, G, and H prevalences range from 7 to 9%, whereas subtype F, J, K, and CRF01-AE strains represent 2 to 4% of the samples; only one subtype B strain was identified. The highest prevalence (25%) of subtype C was in the south, and CRF01-AE was seen mainly in the north. The high intersubtype variability among the V3-V5 sequences is the most probable reason for the low (45%) efficiency of subtype A-specific PCR and HMA (heteroduplex mobility assay). Eighteen (29%) of 62 samples had discordant subtype designations between env and gag. Sequence analysis of the entire envelope from 13 samples confirmed the high degree of diversity and complexity of HIV-1 strains in the DRC; 9 had a complex recombinant structure in gp160, involving fragments of known and unknown subtypes. Interestingly, the unknown fragments from the different strains did not cluster together. Overall, the high number of HIV-1 subtypes cocirculating, the high intrasubtype diversity, and the high numbers of possible recombinant viruses as well as different unclassified strains are all in agreement with an old and mature epidemic in the DRC, suggesting that this region is the epicenter of HIV-1 group M

Characterization of an old complex circulating recombinant form, CRF27_cpx, originating from the democratic republic of Congo (DRC) and circulating in France

Full-length genomes were characterized for two samples, 02CD-LBR024 from the Democratic Republic of Congo (DRC) and 04FR-CD-KZS from France, that formed a separate subcluster with a previously characterized env subtype E isolate from DRC with a recombinant structure different from CRF01-AE. Since the three viruses are clearly epidemiologically unlinked and share the same complex recombinant structure, they represent a circulating recombinant form, designated as CRF27-cpx. The recombination pattern involves six different HIV-1 subtypes (A, E, G, H, J, and K) and a small unclassified fragment. The genetic distances are relatively high, indicating that CRF27-cpx evolved over a long time. Their prevalence is low (0.75%) and remained stable over time in the DRC. The existence of the 04FR. CD. KZS virus, in a patient who recently seroconverted in France, confirmed that these strains now circulate outside the DRC. Continuous monitoring of HIV-1 strains thus remains important to allow early identification of the introduction of new variants

Seroprevalence of HIV-1, HIV-2, and HIV-1 group O in Nigeria : evidence for a growing increase of HIV infection

To determine current data on HIV infection and to further confirm the presence of HIV-1 group O infection in Nigeria, 2300 samples from five states were tested for the presence of HIV antibody. A convenience sampling was obtained from pregnant women, tuberculosis (TB) patients, commercial sex workers (CSWs), blood donors, patients with sexually transmitted diseases (STDs), patients with skin diseases, male clients of CSWs, outpatients suspected bo have AIDS, truck drivers, and community dwellers. With the exception of pregnant women, the HIV prevalences in all these groups were high : 60,6% in CSWs, 16,2% in TB patients, 7,7% in blood donors in some states, and 16% in the rural area of Kano State. Male clients of CSWs, truck drivers, and STD patients had prevalences of 7,8%, 8,6% and 21,2%, respectively. Regional differences in relation to HIV prevalences were observed ; HIV-2 and most of the HIV-1/2 infections were found in the southern states of Nigeria. Higher HIV prevalences were observed in the north-northeast in pregnant women, TB patients, and CSWs, but for blood donors, higher rates were seen in the southeast-southwest. One asymptomatic 50-year-old woman, a community dweller in Kano, was identified to be HIV-1 group O-positive. Compared with data from national surveillance studies in 1991/1992 and 1993/1994, a substantial increase in HIV infection was observed. Our results show a growing incidence of HIV infection in Nigeria and suggest the presence of a rural HIV epidemic. The identification of HIV-1 group O in Kano shows that this virus strain is geographically widespread in Nigeria. (Résumé d'auteur