Genotypic diversity of Mycobacterium tuberculosis in the Guiana-Antilles region

This investigation dealt with 226 strains (1 isolate/patient) of Mycobacterium tuberculosis isolated in the French West Indies and French Guiana over a three-year period (1994-1996). The genotypic diversity of the isolates was investigated using various molecular markers; essentially two PCR-based rapid methods, namely spoligotyping and double-repetitive-element (DRE)-PCR, as well as three restriction fragment length polymorphism (RFLP)-based methods, namely IS6110-RFLP, DR-RFLP and PGRS-RFLP. Out of 226 isolates investigated, a total of 166 isolates were distributed in 31 spoligotype-defined clusters containing 2-31 strains, which corresponded to a rate of 73% of primary clustering. After secondary typing with DRE-PCR, IS6110-RFLP, DR-RFLP and/or PGRS-RFLP, molecular clonality was established for 73 isolates organised in 25 clusters (32% of clustered isolates). Considering one reactivation case per cluster, the rate of recent transmission was estimated to a minimal rate of 21%, however the available epidemiologic information led to the positive conclusion for only 14% of cases. The data obtained demonstrated the presence of common genotypes of M. tuberculosis among the three overseas French territories, i.e. Guadeloupe, Martinique and French Guiana. The results obtained during this retrospective study clearly indicate the importance of future prospective epidemiological investigations around the clustered cases of tuberculosis, so as to detect the persisting foci of endemic disease and characterize the chain of transmission as well as the subpopulations which are at an increased risk of contracting and/or propagating the disease. Last but not least, the present study also deals with a first phylogenetic approach of M. tuberculosis based on a comparison of the spoligotyping results obtained locally with those reported elsewhere in the world.     

Epidemiological study of tuberculosis in the area of Angers,France, as studied by 3 PCR-based fingerprinting methods

The new genotyping methods efficiently complement classical epidemiological investigation in order to attempt a global approach to TB control. In the present work, we have studied the genomic diversity of Mycobacterium tuberculosis isolated during the year 1998 within the district of Angers, France (260,000 inhabitants distributed in 29 districts), in order to identify recent transmission events and any related risk factors. The methods used included "spacer oligonucleotide typing" or spoligotyping, "variable number of DNA tandem repeats" or VNTR, and "double repetitive element PCR" or DRE-PCR. The resulting spoligotyping and VNTR results were also feeded to international databases and compared with >10,000 isolates for spoligotyping and 500 isolates for VNTR, representative of about 60 countries. The results obtained underlined that most of the TB cases in our setting probably reflected reactivation cases, as clustered cases indicative of potential events of recent transmission were rare. Furthermore, interrogation of international databases showed that most of the isolates from the Angers region belonged to major conserved families of TB isolates representative of Europe, with only rare cases of Asian origin, or those previously reported in specific epidemies reported from elsewhere.     

Phylogenetic reconstruction of Mycobacterium tuberculosis within four settings of the Caribbean region: tree comparative analyse and first appraisal on their phylogeography.

In order to compare phylogenetic methods and to reconstruct the evolutionary history of the tubercle bacilli, a set of macro-array-based genotyping data of Mycobacterium tuberculosis clinical isolates (called spoligotyping for spacer oligonucleotide typing, which assays the variability of the Direct Repeat -DR- locus), was analyzed in four settings of the Caribbean region (Guadeloupe, Martinique, Cuba and Haiti). A set of 47 alleles, split into 26 shared and 21 unique alleles) representative of 321 individual M. tuberculosis clinical isolates from patients residing in the above regions was studied. The following methods (and software in brackets) were investigated: numerical taxonomy distance methods (TAXOTRON), maximum parsimony procedure (PAUP), median-joining networks (NETWORK), and nested clade analysis (GEODIS). Results using these methods were analyzed, compared and discussed. The latter method (GEODIS) was investigated in detail by introducing geographical data together with genetic variability results to detect a link between population structure and population history, and to test the null hypothesis of no association between geography and genotypes. Irrespective of the methods used, our findings demonstrate that a core structure of four families (or clades) of M. tuberculosis strains is highly prevalent within the islands studied, indirectly reflecting passed colonization history of these different settings. Specificity of M. tuberculosis genotypes in each of the islands is discussed in the light of their respective colonial and contemporary histories.     

Streptococcus pyogenes bacteraemia: an old enemy subdued, but not defeated

Bacteraemia with Streptococcus pyogenes (Group A haemolytic streptococci) was reviewed in patients admitted to University Hospital, Nottingham over a period of 7 years. Altogether, 40 cases were encountered, representing 2% of all cases of bacteraemia. Mortality was 35%. Most cases were community-acquired and 28% of patients were less than 40 years of age. A third of the patients were previously fit. The most common sources of bacteraemia were the skin and soft tissue (23 patients) and the respiratory tract (eight patients). Shock was recorded in 40% of cases and carried a 60% mortality. This feature of streptococcal bacteremia has not received sufficient attention in the past. Despite its unique susceptibility to penicillin, S. pyogenes continues to pose a challenge to the physician.     

Enhanced humoral response in kappa-opioid receptor knockout mice

Opiates are major analgesics and addictive drugs described also as immunomodulators. Here, we investigated the contribution of kappa-opioid receptor (KOR) activity in immunity in vivo by studying immune responses in KOR knockout mice. These animals displayed a modest reduction in thymus cellularity and CD4(+) cell ratio, parallel to a slight increase in immature CD4(+)CD8(+) lymphocytes. In spleen, KOR null animals showed augmented cell number with no change in cell distribution. T and B lymphocyte proliferative capabilities in vitro, Natural Killer activity and steady-state Ig levels were unchanged in KOR-/- mice. We immunized the mice with the antigen keyhole limpet hemocyanin (KLH). Compared to wild-type (WT) mice, KOR-/- animals produced significant higher levels of antigen-specific total Ig, IgM, IgG1 and IgG2a antibodies. This enhancement of humoral activity was not observed in mu-opioid receptor and delta-opioid receptor knockout animals. These results show that endogenous activation of kappa-opioid receptors may exert a tonic inhibition of antibody (Ab) response.     

Inverse agonism and neutral antagonism at wild-type and constitutively active mutant delta opioid receptors

The delta opioid receptor modulates nociceptive and emotional behaviors. This receptor has been shown to exhibit measurable spontaneous activity. Progress in understanding the biological relevance of this activity has been slow, partly due to limited characterization of compounds with intrinsic negative activity. Here, we have used constitutively active mutant (CAM) delta receptors in two different functional assays, guanosine 5'-O-(3-thio)triphosphate binding and a reporter gene assay, to test potential inverse agonism of 15 delta opioid compounds, originally described as antagonists. These include the classical antagonists naloxone, naltrindole, 7-benzylidene-naltrexone, and naltriben, a new set of naltrindole derivatives, H-Tyr-Tic-Phe-Phe-OH (TIPP) and H-Tyr-TicPsi[CH2N]Cha-Phe-OH [TICP(Psi)], as well as three 2',6'-dimethyltyrosine-1,2,3,4-tetrahydroquinoline-3-carboxylate (Dmt-Tic) peptides. A reference agonist, SNC 80 [(+)-4-[(alphaR)-alpha-((2S,5R)-4-Allyl-2,5-dimethyl-1-piperazinyl)-3-methoxybenzyl]-N,N-diethylbenzamide], and inverse agonist, ICI 174864 (N,N-diallyl-Tyr-Aib-Aib-Phe-Leu), were also included. In a screen using wild-type and CAM M262T delta receptors, naltrindole (NTI) and close derivatives were mostly inactive, and TIPP behaved as an agonist, whereas Dmt-Tic-OH and N,N(CH3)2-Dmt-Tic-NH2 showed inverse agonism. The two latter compounds showed negative activity across 27 CAM receptors, suggesting that this activity was independent from the activation mechanism. These two compounds also exhibited nanomolar potencies in dose-response experiments performed on wild-type, M262T, Y308H, and C328R CAM receptors. TICP(Psi) exhibited strong inverse agonism at the Y308H receptor. We conclude that the stable N,N(CH3)2-Dmt-Tic-NH2 compound represents a useful tool to explore the spontaneous activity of delta receptors, and NTI and novel derivatives behave as neutral antagonists.     

Facteurs prédictifs de dysfonction rénale postopératoire après arthroplasties totales de hanche

Introduction

Postoperative renal dysfunction (PRD) is well-documented after cardiovascular surgery but there are only limited available data concerning major orthopedic surgery, although patients may have several risk factors prone to impair renal function. We designed an epidemiologic prospective study to assess the incidence of PRD after total hip arthroplasty (THA) and to determine risk factors.

Patients and methods

Were included in the study 755 patients scheduled for THA in a single centre, over a 14 months period. Thirty-one demographic, clinical and biological parameters were collected for each patient. PRD was defined by a value of glomerular filtration, determined by the Cockroft and Gault formula ≤ 60 ml/min per 1.73 m², on the seventh postoperative day. Risk factors were determined by univariate and then multivariate analyses using a linear regression model.

Results

Pre- and postoperatively (POD7), respectively 22.4% and 31.4% of the patients, had a creatinine clearance less than 60 ml/min per 1.73 m². Univariate analysis documented age, ASA score, diabetes mellitus, chronic hypertension, the use of diuretics and NSAID, anemia, and an increased value of plasma urea as risk factors. Risk factors documented by multivariate analysis were: preoperative creatinine clearance less than 60 ml/min per 1.73 m², (OR: 5.8, 95% confidence interval: [1.6–8.1], p = 0.0006), preoperative plasma urea greater than 7.49 mmol/l (2.1 [1.4–11.1], p = 0.04), age above 70 years (1.8 [1.1–4.3], p = 0.02), and duration of NSAID's treatment beyond 5 days (3.2 [1.4–7.1], p = 0.02).

Conclusion

PRD is common after THA and is prone to develop in aged patients with comorbidities. Duration of NSAID's administration should be limited in those patients.