Specificities and functions of the recA and pps1 intein genes of Mycobacterium tuberculosis and application for diagnosis of tuberculosis

The worldwide recrudescence of tuberculosis and the widespread appearance of antibiotic resistance have strengthened the need for rapid and specific diagnostic tools. The prevailing microbiological identification of Mycobacterium tuberculosis, the causative agent of tuberculosis, which implies the use of in vitro cultures and acid-fast staining microscopy, is time-consuming. Detection of M. tuberculosis directly in clinical samples through PCR amplification of mycobacterium-specific genes, designed to shorten diagnostic delay, demonstrated reliability and high sensitivity. However, the quality of the diagnosis depends on the specificity of the target sequence for M. tuberculosis complex strains. In the present study, we demonstrated the specificity of recA and pps1 inteins for this complex and thus the feasibility of using intein-coding sequences as a new target for PCR diagnosis. Indeed, the recA and pps1 genes of 36 clinical isolates of M. tuberculosis and 10 field strains of M. bovis were found to be interrupted by an intein sequence at the RecA-a and Pps1-b sites, respectively, while a large number of nontuberculous mycobacterial species failed to demonstrate these insertions. Besides, the MtuPps1, which was cloned and expressed in Escherichia coli, was shown to possess an endonuclease activity. The intein cleaves the 40-bp sequence spanning the intein insertion site Pps1-b in the inteinless pps1 gene. In addition to the PCR amplification of recA and pps1 intein genes as a tool for diagnosis, the specific endonuclease activity could represent a new molecular approach to identify M. tuberculosis.     

An association of HIV infection and noma in Niger

We report a case of noma having occurred in an adult female patient with HIV. The strain was characterized as HIV-1 group M subtype G. In order to explore the interactions between HIV/AIDS and this disease, we purpose systematic HIV screening for any case of noma, especially for adult patients.     

Rheumatoid arthritis in Senegal: a comparison between patients coming from rural and urban areas, in an urban tertiary health care center in Senegal

Several studies have suggested that rheumatoid arthritis (RA) is uncommon in rural sub-Saharan Africa. The aim of this study is to determine the potential differences between patients with RA living in rural areas and those living in urban areas. We performed a cross-sectional study from June 2006 to May 2009. We included all patients with RA (1987 ACR criteria) seen at the Rheumatology Unit of the Le Dantec Teaching Hospital, Dakar, Senegal. We compared the main socio-demographic and clinical characteristics of patients living in rural areas to those living in urban areas. We included 180 patients in our study, of whom, 143 (79.4?%) lived in urban areas and 37 (20.6?%) in rural areas. The median age was 44?years [range 34–55] in patients from rural areas vs. 41?years [range 30–53] in patients from urban areas, without any statistical significance (p?=?0.24). Patients under the age of 60 mostly lived in urban areas (p?=?0.03). The extra-articular manifestations were significantly more frequent in patients living in rural areas (p?=?0.02). There was no statistical significance when comparing the delay in diagnosis, number of swollen joints, disease activity, hand deformities, and concentration of autoantibodies (RF and ACPA) in both populations. The percentage of patients seen from the rural areas of Senegal is low (20.6?%) compared to those seen from the urban areas. The number of extra-articular manifestations is the main difference between patients living in rural and urban areas. The role played by environmental factors seems important. Further incidence studies are needed.     

Prise en charge diagnostique et thérapeutique des tumeurs épithéliales malignes de l’ovaire dans le centre ouest-africain de lutte contre le cancer de Dakar

IntroductionEpithelial ovarian cancer are the most frequent of ovarian cancer, their prognosis is very bad. The aim of this study is to describe the diagnosis, the treatment and to assess the survival rate of the patients.MethodsIt was a retrospective study realized at the Cancer Institute of Dakar from December 2000 to January 2007. We have collected 117 patients with epithelial ovarian cancer. The mean age was 49 years. Patients were comprised: 22 stage I, 32 stage II, 35 stage III and 26 stage IV. Primary surgery was performed to 34 patients and the other patients were treated with chemotherapy and surgery. The survival rate was assessed by Kaplan-Meier method and the Logrank test had allowed to compare the survival among age and optimal surgery.ResultsOptimal surgery R0 was done in 20 cases and surgical resection R2 was performed in 45 cases. Pathological exam had found 65 serous cystadenocarcinoma, 28 mucinous cystadenocarcinoma and 21 endometrioid cystadenocarcinoma, one malignant tumor of Brenner. Overall survival at five years was 13.3%. The survival among optimal surgery was 16.3 and 2.3% for suboptimal surgery. There was no significant difference of the survival among patients who were less than 40 years old (P  =  0.334).ConclusionPrognosis of epithelial ovarian cancer is worse in Senegal as like as in the world. To improve the survival of our patients, we must detect the early diagnosis of these tumors and to introduce the neoadjuvant chemotherapy before optimal surgery.     

A test of the chromosomal theory of ecotypic speciation in Anopheles gambiae

The role of chromosomal inversions in speciation has long been of interest to evolutionists. Recent quantitative modeling has stimulated reconsideration of previous conceptual models for chromosomal speciation. Anopheles gambiae, the most important vector of human malaria, carries abundant chromosomal inversion polymorphism nonrandomly associated with ecotypes that mate assortatively. Here, we consider the potential role of paracentric inversions in promoting speciation in A. gambiae via "ecotypification," a term that refers to differentiation arising from local adaptation. In particular, we focus on the Bamako form, an ecotype characterized by low inversion polymorphism and fixation of an inversion, 2Rj, that is very rare or absent in all other forms of A. gambiae. The Bamako form has a restricted distribution by the upper Niger River and its tributaries that is associated with a distinctive type of larval habitat, laterite rock pools, hypothesized to be its optimal breeding site. We first present computer simulations to investigate whether the population dynamics of A. gambiae are consistent with chromosomal speciation by ecotypification. The models are parameterized using field observations on the various forms of A. gambiae that exist in Mali, West Africa. We then report on the distribution of larvae of this species collected from rock pools and more characteristic breeding sites nearby. Both the simulations and field observations support the thesis that speciation by ecotypification is occurring, or has occurred, prompting consideration of Bamako as an independent species.     

Oesophageal atresia: Diagnosis and prognosis in Dakar,Senegal

Background:

Oesophageal atresia is a neonatal emergency surgery whose prognosis has improved significantly in industrialised countries in recent decades. In sub-Saharan Africa, this malformation is still responsible for a high morbidity and mortality. The objective of this study was to analyse the diagnostic difficulties and its impact on the prognosis of this malformation in our work environment.

Patients and Methods:

We conducted a retrospective study over 4 years on 49 patients diagnosed with esophageal atresia in the 2 Paediatric Surgery Departments in Dakar.

Results:

The average age was 4 days (0-10 days), 50% of them had a severe pneumonopathy. The average time of surgical management was 27 h (6-96 h). In the series, we noted 10 preoperative deaths. The average age at surgery was 5.7 days with a range of 1-18 days. The surgery mortality rate is 28 patients (72%) including 4 late deaths.

Conclusion:

The causes of death were mainly sepsis, cardiac decompensation and anastomotic leaks.Key words: Esophageal atresia, Diagnosis, Prognosis, Sub-Saharan Africa