Biomedical subjects

G Prod'hom

Publications and source records attributed to G Prod'hom.

8 recordsLinked to original sources

PubMed1998

A reliable amplification technique for the characterization of genomic DNA sequences flanking insertion sequences.

A simple and efficient ligation-mediated PCR (LMPCR) is described for amplifying DNA adjacent to known sequences. The method uses one primer specific for the known sequence and a second specific for a synthetic linker ligated to restricted genomic DNA. Perkin-Elmer AmpliTaq Gold polymerase is used to minimize non-specific primer annealing and amplification. This LMPCR method was successfully applied to isolate DNA sequences flanking mobile elements present in mycobacterial mutants generated by transposon mutagenesis.

Cloning, Molecular↗

PubMed1998

Identification of genetic loci implicated in the survival of Mycobacterium smegmatis in human mononuclear phagocytes.

A luminescence-based procedure that permits the rapid evaluation of the survival of mycobacteria within mononuclear phagocytes was developed and used to screen insertional mutants of Mycobacterium smegmatis for their ability to survive in human monocyte-derived macrophages. Among the 5000 mutants tested, eight mutants were identified that demonstrated impaired intracellular survival in human macrophages but that grew normally in the absence of cells. For each mutant, a portion of the gene interrupted by the transposition event was amplified by ligand-mediated PCR and sequenced. In all cases, the existence of homologous genes of as yet unknown function were identified in the Mycobacterium tuberculosis genome. Complementation of the mutant mycobacterial strains with cosmids containing the homologous loci from M. tuberculosis restored normal intracellular growth in three of the four mutants tested, supporting the idea that these loci contain genes that are important for intracellular survival. This study demonstrates the feasibility of directly screening mutant mycobacterial strains to identify genes coding for activities necessary for the intracellular survival in human mononuclear phagocytes, an important initial step in the identification of potential targets for new therapeutic agents.

Base Sequence↗

PubMed1997

Comparison of a new insertion element, IS1407, with established molecular markers for the characterization of Mycobacterium celatum.

Genomic analyses of 18 Mycobacterium celatum strains obtained from different patients in three countries (United States, United Kingdom, and France) were performed; the methods used in this study were restriction fragment length polymorphism (RFLP) analysis, pulsed-field gel electrophoresis (PFGE) analysis, and PCR restriction analysis (PRA) of the hsp-65 gene. A new insertion sequence, IS1407 (GenBank accession no. X97307), belonging to the IS256 family, was identified in M. celatum type 1 strains and was characterized by sequencing. When a probe for Mycobacterium xenopi IS1395-like sequences was used, the RFLP analysis of M. celatum type 1 strains revealed that they contained three or four copies of IS1407 in identical genomic positions, while this element was absent in all M. celatum type 2 strains. PFGE performed with three different endonucleases revealed a unique large restriction fragment (LRF) pattern for M. celatum type 1 strains, whereas the LRF patterns obtained for M. celatum type 2 strains were polymorphic. Moreover, PFGE of nondigested genomic DNA revealed extrachromosomal elements in M. celatum type 2. The type strain of M. celatum type 3 could not be differentiated from M. celatum type 1 strains on the basis of the results of the RFLP analysis, the PFGE analysis, and the PRA of IS1407. In this study we confirmed that M. celatum types 1 and 2 represent distinct genomic clusters and that the molecular markers in M. celatum type 2 exhibit greater polymorphism than the molecular markers in M. celatum type 1.

Bacterial Proteins↗

PubMed1997

Rapid discrimination of Mycobacterium tuberculosis complex strains by ligation-mediated PCR fingerprint analysis.

A ligation-mediated PCR (LMPCR) method for the amplification of sequences flanking the IS6110 of the Mycobacterium tuberculosis complex has been developed. The method uses one primer specific for IS6110 and a second specific for a linker ligated to SalI-restricted genomic DNA. LMPCR is a rapid screening method, valuable for the fingerprinting of M. tuberculosis complex strains.

Bacterial Typing Techniques↗

PubMed1994

Nosocomial pneumonia in mechanically ventilated patients receiving antacid, ranitidine, or sucralfate as prophylaxis for stress ulcer. A randomized controlled trial.

OBJECTIVE: To assess three anti-stress ulcer prophylaxis regimens in mechanically ventilated patients for bacterial colonization, early- and late-onset nosocomial pneumonia, and gastrointestinal bleeding. DESIGN: Randomized controlled trial. PATIENTS: Consecutive eligible patients with mechanical ventilation and a nasogastric tube. Of 258 eligible patients, 244 were assessable. SETTING: Medical and surgical intensive care units. INTERVENTION: At intubation, patients were randomly assigned to receive one of the following: antacid (a suspension of aluminum hydroxide and magnesium hydroxide), 20 mL every 2 hours; ranitidine, 150 mg as a continuous intravenous infusion; or sucralfate, 1 g every 4 hours. MEASUREMENTS: Using predetermined criteria, the incidence of gastric bleeding, gastric colonization, early-onset pneumonia, and late-onset pneumonia was assessed in patients intubated for more than 24 hours. RESULTS: Of 244 assessable patients, macroscopic gastric bleeding was observed in 10%, 4%, and 6% of patients assigned to receive sucralfate, antacid, and ranitidine, respectively (P > 0.2). The incidence of early-onset pneumonia was not statistically different among the three treatment groups (P > 0.2). Among the 213 patients observed for more than 4 days, late-onset pneumonia was observed in 5% of the patients who received sucralfate compared with 16% and 21% of the patients who received antacid or ranitidine, respectively (P = 0.022). Mortality was not statistically different among the three treatment groups. Patients who received sucralfate had a lower median gastric pH (P < 0.001) and less frequent gastric colonization compared with the other groups (P = 0.015). Using molecular typing, 84% of the patients with late-onset gram-negative bacillary pneumonia were found to have gastric colonization with the same bacteria before pneumonia developed. CONCLUSION: Stress ulcer prophylaxis with sucralfate reduces the risk for late-onset pneumonia in ventilated patients compared with antacid or ranitidine.

Adult↗

PubMed1991

[Progress and problems in hospital infections: exemplified by pneumonia].

Nosocomial pneumonias have various etiologies and their development depends mainly on the underlying condition of the patients. Intubated patients are prone to development of bacterial pneumonia from the oropharyngeal or gastric flora. Prevention relies on reducing exogenous as well as endogenous colonization of the bronchotracheal tree: avoidance of cross-contamination, maintenance of a physiological gastric pH and, possibly, selective digestive decontamination. Neutropenic patients may develop invasive aspergillus infection. Prevention depends on appropriate air filtration. Patients with cellular immunodeficiency are susceptible to various agents. Prevention of legionella depends on control of the water and ventilation systems. The prevention of cytomegalovirus infection includes the screening of blood products for certain patients and, in some cases, the administration of hyperimmune gammaglobulins and possibly ganciclovir. Even though Pneumocystis carinii pneumonia is thought to be due to reactivation, recent evidence suggests that transmission may occur between patients and therefore appropriate respiratory isolation is advisable. Finally, nosocomial tuberculosis is an increasing problem in which control depends on early diagnosis and treatment of patients as well as on appropriate air exchange in particular rooms of the hospital. In conclusion, the prevention of nosocomial pneumonia includes numerous measures which largely depend on the type of microorganisms.

Aspergillosis, Allergic Bronchopulmonary↗

PubMed1985

[Relationship between solid cell nests and focal lymphocytic thyroiditis].

Considering the fact that there is often a combined occurrence of focal lymphocytic thyroiditis (FLT) and so-called Solid Cell Nests (SCN) in the same human thyroid gland, we examined thyroid tissue of 500 routine autopsies. SCN were found in 56 (11.2%) and FLT in 59 (11.8%) patients. The combination of these two lesions was encountered in 18 (3.6%) cases. This incidence (3.6%) is four to five times higher than would be expected from chance alone. In 12 of the 18 patients mentioned, SCN were in close association with lymphocytic infiltration, but this was not statistically significant. Two hypotheses are discussed concerning the combination of SCN and FLT. According to Klinck and Menk (1951), the SCN, derived like the epithelial part of the thymus from the embryologic pharyngeal pouch, forms a favorable micro-environment for inflammatory cells. Based on the second hypothesis, the SCN, probably a remnant of the ultimobranchial body, mark an incompletely developed thyroid. These thyroids would be predisposed to auto-immune thyroid disease such as FLT.

Adult↗

PubMedDate not supplied

Molecular epidemiology of tuberculosis among HIV-infected persons in Switzerland: a countrywide 9-year cohort study. Swiss HIV Cohort Study.

We investigated tuberculosis transmission during a nine-year period (1988-1996) in a countrywide community-based cohort of HIV-infected persons in Switzerland (the Swiss HIV Cohort Study [SHCS]). We estimated the proportion of tuberculosis cases due to reinfection and relapse, and assessed factors which may increase the risk of tuberculosis transmission. HIV-infected persons were followed prospectively and molecular fingerprinting with insertion sequence (IS) 6110, 36-bp direct repeat, and IS6110-PCR was used to determine M. tuberculosis case clustering. Out of 7999 SHCS participants, 267 persons developed tuberculosis. 158 M. tuberculosis isolates from 138 patients were available for study. Molecular analysis identified 33 (24%) episodes of tuberculosis associated with 12 clusters including 2 to 8 patients. Two patients experienced reinfection, and nine had a relapse. Detailed contact investigation identified definite or possible epidemiological links between 21 of 33 cluster patients (64%). Multivariate logistic regression analysis did not identify any risk marker significantly associated with clustering. During a nine-year period, one fourth of tuberculosis cases were grouped in clusters within a selection of 138 HIV-infected patients. This may represent the lowest estimation of recently acquired tuberculosis infection. There were no large institutional or community outbreaks among HIV-infected participants of the Swiss HIV Cohort Study.

AIDS-Related Opportunistic Infections↗