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Biomedical subjects

D Camus

Publications and source records attributed to D Camus.

At least 127 records · Page 7Linked to original sources
PubMedDate not supplied

Pneumocystis carinii: an atypical fungal micro-organism.

The purpose of this review is to assist mycologists in having a better understanding of Pneumocystis carinii and the disease that it causes. Now considered to be a fungus, P. carinii is unusual in its life cycle and relationship with the host. P. carinii pneumonia (PCP) pathogenesis, immunology and host defence mechanisms are examined, as well as epidemiological and control strategies. Most pneumocystosis pathophysiological changes result from the parasite's attachment and proliferation in the lungs, resulting in a filling of the alveoli with masses of the micro-organism. Pathological changes include an increase in alveolar capillary membrane permeability and injury to the alveolar epithelium, which may be mediated by the release of degradative enzymes from the pathogen. A host response takes place by hypertrophy, and hyperplasia involving type II epithelial alveolar cells. P carinii interacts with pulmonary surfactants by binding to the hydrophilic proteins A and D, and by modifying their phospholipid composition. Alveolar macrophages and CD4+ T cells play a key role in the host's defence against Pneumocystis. The epidemiology of PCP remains poorly understood. Airborne transmission has been established, but the actual infective form and its source remains unknown. Studies concerning P. carinii genetic diversity have shown that the parasite polymorphism is related, at least partially, to the host species. A strong host-species specificity in P. carinii has been found. From an epidemiological perspective, there appears to be no animal reservoir for the agent of human PCP. Thus, this disease should not be considered to be zoonotic. Although a significant decrease in the incidence of pneumocystosis has been obtained when employing chemoprophylaxis, anti-P. carinii drugs are not completely successful, often inducing deleterious side-effects. For these reasons, new prophylactic and therapeutic strategies need to be developed. One approach could be based on the anti-P. carinii effect of yeast killer toxins and antibiotic anti-idiotypic antibodies.

Animals↗
PubMedDate not supplied

Kinetic study of antifungal activity of amphotericin B, 5-fluorocytosine and ketoconazole against clinical yeast isolates using liquid-phase turbidimetry.

The fungal growth of clinical yeast isolates and of VW32 clone of Candida albicans were measured in vitro using a liquid-phase turbidimetric system (Bioscreen from Labsystems, France) in defined conditions. Cultures were performed in Shadomy's liquid medium and the fungal growth automatically evaluated every 10 minutes for 24 hours using various concentrations of drugs. The system made it possible to test 200 culture samples in one experiment. Yeast sensitivity to drugs was also measured by using our routine semi-automatic turbidimetric system. We observed that kinetic patterns of activity of each antifungal agent were typical. The in vitro tests showed that of 927 clinical yeast isolates 99.2% were sensitive to amphotericin B, 94.4% to 5-fluorocytosine and 69.7% to ketoconazole.

Amphotericin B↗
PubMedDate not supplied

Ultrastructural study of Pneumocystis carinii in explant cultures of rabbit lung and in cultures with and without feeder cells.

Pneumocystis carinii-parasitized lung explants were obtained from corticoid-treated rabbits and maintained in vitro. Twenty-one days after the beginning of explant cultures, the ultrastructural morphology of trophozoite, precyst and cyst forms was normal as compared to the in vivo ultrastructure of P. carinii from infected rabbit. However, after the 36th day, only altered forms of P. carinii were observed. Lung tissue showed only minor alterations. Intracytoplasmic lamellar inclusions were observed in type 2 alveolar cells from which they were released. While the total number of parasites increased approximately 4-fold from day 0 to day 41, trophozoite counts increased approximately 6 times. Pneumocystis cells from inocula and supernates of cultures with and without Vero cells showed important ultrastructural alterations.

Animals↗
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Three-dimensional reconstruction of rabbit-derived Pneumocystis carinii from serial-thin sections. I: Trophozoite.

The highly complex ultrastructural morphology of the endomembrane system in Pneumocystis carinii led us to perform three-dimensional reconstruction from serial-thin sections using the CATIA (Conception Assistée Tridimensionnelle Inter Active) Dassault system program. The three-dimensional reconstruction of a small trophozoite made it possible to better understand the morphological relationship among organelles and to suggest cytophysiological hypotheses. By reconstructing other parasite stages, we gathered information about the evolution of organelles during the life cycle and about their physiology.

Animals↗
PubMedDate not supplied

Three-dimensional reconstruction of rabbit-derived Pneumocystis carinii from serial-thin sections. II: Intermediate precyst.

Three-dimensional reconstruction of a binucleate intermediate precyst of Pneumocystis carinii was performed from serial-thin sections using the CATIA (Conception Assistée Tridimensionnelle Inter Active) Dassault system program. The presence of a mitochondrion, complex well-developed endoplasmic structures, and numerous Golgi vesicles was established. A better understanding of the ultrastructure of rabbit-derived P. carinii stages made it possible to formulate hypotheses on the evolution and physiology of the endomembrane system. Thus, the presence of the well-developed endoplasmic saccular structure and more than 230 Golgi vesicles in its vicinity might be implicated in the differentiation of the parasite surface structures and might also be related to nuclear division and individualization of intracystic bodies.

Animals↗
PubMedDate not supplied

Polymorphism of the thymidylate synthase gene of Pneumocystis carinii from different host species.

Pneumocystis carinii is an opportunistic agent found in the lung of various mammals which often causes severe pneumonia in immunocompromised humans, especially in AIDS patients. In the past several years significant additions have been made to the collection of knowledge we have concerning the genetic diversity of P. carinii. These additions provide new understanding of Pneumocystis transmission and the effect of possible reservoirs of Pneumocystis in the various species. In this study, a 400-bp fragment of the thymidylate synthase (TS) gene of P. carinii has been amplified by PCR from 43 parasite isolates obtained from 4 mammalian host species: rat, mouse, rabbit and human. A probe selected from the TS gene sequence of rat-derived P. carinii was hybridized with the amplified products from rat- and mouse-derived P. carinii, but not with rabbit or human P. carinii DNA. Restriction profiles were performed on amplified fragments from all isolates, and the 4 nucleotide sequences of the TS gene fragment amplified from rat, mouse, rabbit and human P. carinii were determined. Differences were detected in the gene fragment in P. carinii isolates from the 4 host species; however no difference was revealed in P. carinii isolates within a single host species, whatever the host strain or its geographic origin. Thus, the sequence differences of the P. carinii TS gene appeared as host-species specific. A specific probe which recognized all human P. carinii isolates was defined.

Amino Acid Sequence↗
PubMedDate not supplied

Molecular cloning and characterization of a superoxide dismutase (sod) gene in Pneumocystis carinii.

This work reports the isolation and characterization of a gene encoding a superoxide dismutase (SOD, EC.1.15.1.1.) from Pneumocystis carinii derived from rat. Sense and antisense oligonucleotides, deduced from SOD amino acid sequences from a wide variety of organisms, allowed amplification of a 669 bp genomic DNA fragment specific to this P. carinii. RACE-PCR was used to obtain the major part of the complementary DNA; the 5'- and 3'-genomic regions were obtained respectively from a Mbol subgenomic library and from an amplified fragment using oligonucleotides designed from the cDNA sequence. Comparison of genomic and cDNA sequences showed an open reading frame of 660 bp interrupted by seven small introns. The deduced amino acid sequence contained 220 residues. Protein sequence alignment demonstrated the highest homology (50.5% identity; 70.3% similarity) with Saccharomyces cerevisiae manganese-SOD (MnSOD) suggesting that P. carinii SOD belongs to the mitochondrial MnSOD group. A putative targeting peptide found at the 5'-end of the P. carinii SOD sequence also suggested its mitochondrial localization.

Amino Acid Sequence↗
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Case report: recovery of Calliphora vicina first-instar larvae from a human traumatic wound associated with a progressive necrotizing bacterial infection.

Human myiasis caused by Calliphora vicina is rare in Europe. Here we report a case of C. vicina infection occurring in the traumatic leg wound of a healthy 21-year-old man. Firstly, a progressive necrotizing infection developed in the wound despite administration of antibiotics. Aeromonas hydrophila was isolated from the wound samples. Secondly, during debridement, C. vicina first-instar larvae were isolated from the wound. To our knowledge, this is the first European case of C. vicina wound myiasis associated with severe A. hydrophila infection.

Adult↗
PubMedDate not supplied

[Cyclospora cayetanensis: review of an emerging intestinal pathogen].

Cyclospora cayetanensis is an emerging pathogen. It is a new human coccidian agent of intestinal disease. Twenty years ago, the first known human cases of cyclosporiasis were reported in the medical literature. Cyclosporiasis occurs in persons of all ages and either in immunocompetent or immunocompromised hosts. The most characteristic feature of this infection is a syndrome of acute or chronic diarrhea. This parasite has a world-wide distribution. In previous reports, Cyclospora cayetanensis was associated with prolonged diarrhea in travellers, returning from developing countries. However, Cyclospora infection has recently been reported in non travellers in the United States and Canada. Cyclospora can be transmitted by ingestion of water or food contaminated with oocysts. The life cycle of Cyclospora cayetanensis is not fully known. Diagnosis of cyclosporiasis is made by direct examination of stool samples. To date, oral trimethoprim-sulfamethoxazole is the only effective treatment for Cyclospora infection.

Animals↗