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J Bernet

Publications and source records attributed to J Bernet.

At least 19 recordsLinked to original sources
PubMed2006

[Cutaneous leishmaniasis in polymyositis].

INTRODUCTION: The prevalence of cutaneous leishmaniasis is increasing, especially in immunocompromized subjects. CASE RECORD: We report a case of particular interest, where a patient with steroid refractory polymyositis developed cutaneous leishmaniasis. Clinical outcome was favorable after institution of intralesional antimony therapy. DISCUSSION: Cutaneous leishmaniasis is still recognized to be an opportunistic infection. Its frequency is indeed higher in immunocompromized subjects, mainly HIV-infected patients. In our patient, both polymyositis and steroid therapy were predisposing factors of cutaneous leishmaniasis onset; prednisone therapy has been postulated to be associated with immune dysfunction leading to: reduced blood T cells' levels (CD4 et CD8) as well as decreased cytokine synthesis (e.g. interferon gamma).

Adult↗
PubMed1988

[Optochiasmatic tuberculoma and MRI. 2 cases].

Two cases are reported of optochiasmatic tuberculoma, an exceptional complication difficult to diagnose in the absence of any tuberculous context. Although diagnosis of the optochiasmatic occupying process is simple by scan or NMR imaging, it is generally difficult to identify the chiasma in a process of this type. It is therefore impossible to recognize the two forms of these tuberculomas: intra- and peri-chiasmatic histologic types, and yet these have an incidence on therapy and prognosis. Surgical exploration is justified when the diagnosis remains in doubt or when the functional prognosis is implicated.

Adult↗
PubMed1981

Polypeptide synthesis during protoplasmic incompatibility in the fungus Podospora anserina.

In Podospora anserina, self-lysis resulting from the combination of the R and V incompatibility genes is accompanied by the appearance, in lysing cells, of specific enzyme activities, among which is a laccase exoenzyme, and by a quenching of ribonucleic acid synthesis. Present results show that the occurrence of the laccase is the result of de novo synthesis. By means of two-dimensional gel electrophoresis it was shown that the onset of self-lysis is accompanied by the immediate shut-off of more than 60% of the pre-existing normal polypeptide synthesis and the occurrence of at least 20 new polypeptides. The synthesis of these new polypeptides is active for several hours after the cessation of RNA synthesis, concurrently with the synthesis of about 30 normal polypeptides which is maintained. These modifications of protein synthesis are not accompanied by a concomitant variation in the level of polysomes. It is deduced that incompatibility genes are involved in the control of both transcription and translation.

Ascomycota↗
PubMed1979

Podospora anserina mutant defective in protoperithecium formation, ascospore germination, and cell regeneration.

A mutant (modx) was selected on the basis of the suppression of self-lysis due to a recessive mutation (modB). modx, a dominant mutation, reduced hyphal branching from nonapical cells, abolished protoperithecium formation, and induced the death of stationary cells only when these were isolated to obtain further development. Mutant ascospores, formed in the fruiting bodies which occasionally occur under specific conditions (32 degrees C on starved medium), showed a delay in the germination process (up to 3 months instead of about 5 h for wild-type ascospores) when submitted to incubation under standard conditions (26 degrees C on germination medium) and failed to germinate at 18 degrees C. Revertants from modx strains, selected on the basis of the suppression of the nonrenewal of growth from stationary cells, were wild type for all the other three defects. Indirect arguments suggested that the modx mutant strain might be defective in the control of a specific class of stable messenger ribonucleic acids which would be essential for the physiology of ascospores and stationary cells.

Alleles↗
PubMed1976

Regulation of proteolytic enzymes in Podospora anserina: selection and properties of self-lysing mutant strains.

Previous results showed that cell disintegration in the fungus Podospora anserina occured through the action of two proteases, enzymes whose messengers were normally latent during the extension stage of the thallus. We selected three mutant strains in which the constitutive activity of the protease messengers was expressed by an arrest of growth early in development (10 to 30 hours after spore germination) and a reaction of cell disintegration, in the thallus, suppressible with beta-phenyl pyruvic acid, a protease inhibitor. The mutant character is recessive in one strain. In the case of the two strains in which the mutant trait is dominant, reversion studies have revealed that the deregulation resulted from the specific interaction between two genes and we have succeded in creating two non allelic incompatibility systems comparable to the non allelic gene interactions responsible for the incompatibility phenomena found between wild type races. We know, on the whole, that 11 loci are involved in the regulation of the proteases: five were revealed as incompatibility loci and six were discovered from investigations on four self-lysing mutant strains. It is suspected that all these genes act at the post-transcriptionnal level of the synthesis of specific proteolytic enzymes. We propose that the products of two genes act as "repressors" to prevent the protease messengers from being constitutively translated and that the products of the nine remaining genes exert a positive control by inducing translation, at the appropriate time, through the action of effectors resulting from specific interloci cooperation.

Alleles↗
PubMed1976

A constitutive mutation in a posttranscriptional regulator gene for a phenoloxidase and proteases in Podospora anserina.

A recessive mutation in the gene mod-2 results in the synthesis at low temperatures of a phenoloxidase and an arrest of growth, reversible by beta-phenyl-pyruvic acid, a protease inhibitor. Phenoloxidase synthesis is 5-fluorouracil resistant and cycloheximade sensitive. Suppression of both cold sensitivity and phenoloxidase synthesis by common factors (higher NH4+ concentrations or mutations) suggests that the protease, suspected to be responsible for cold sensitivity, also arises from preexisting mRNA molecules. Instead of being recessive and constitutive, the mod-2 mutations is suppressive and dominant when cold sensitivity and phenoloxidases synthesis are induced as the consequence of the nonallelic gene interactions C/D, C/E, or R/V responsible for protoplasmic incompatibility. Combinations of nonallelic incompatibility systems and several mod-2 mutations lead us to hypothesize that the translational control of the above proteins depends on conformational relationships between incompatibility gene products and mod-2.

Ammonia↗
PubMed1976

The molecular mechanism of protoplasmic incompatibility and its relationship to the formation of protoperithecia in Podospora anserina.

In Podospora anserina, protoplasmic incompatibility due to interactions between non-allelic genes was suppressed by the effect of mutations in two modifier genes, mod-I and mod-2. It is shown that mod-I and mod-2 are involved in the production of three specific proteins, a phenoloxidase and two previously identified proteases (Bégueret & Bernet 1973 a) which are associated with the phenomenon of protoplasmic disintegration. These enzymes, whose messengers are normallly latent during vegetative growth, appear at this stage of the life cycle only as a consequence of incompatible gene interactions. The mode-I and mod-2 genes and each of the five incompatibility loci involved in non-allelic incompatibility systems also participate in the formation of the protoperithecia. This pleiotropic effect suggests that protoplasmic incompatibility is a deviation in the normal physiological processes of protoperithecial formation.

Ascomycota↗
PubMed1974

Protoplasmic incompatibility and female organ formation in Podospora anserina: Properties of mutations abolishing both processes.

A genetic block, effective only with the addition of mutations in two genes, suppresses both the incompatibility process in strain confrontation ("barrage") and the formation of female organs. Investigation on this block lead us to propose that it operates at the ribosomal level and prevents the translation of the messenger of a proteolytic enzyme, a postulated early protein in protoperithecia differenciation.

Ascomycota↗
PubMed1974

Incompatibility in Podospora anserina: comparative properties of the antagonistic cytoplasmic factors of a nonallelic system.

In the fungus Podospora anserina, the interaction between the nonallelic incompatible R and V genes has two consequences: a lytic reaction due to the synthesis of specific proteolytic enzymes, and a quenching in protein and ribonucleic acid synthesis. The incompatibility reaction when vegetative or sexual R and V cells fuse is asymmetric: it is induced only in the R protoplasm. The cessation in ribonucleic acid and protein synthesis was investigated in heterokaryotic strains carrying the antagonistic R and V genes and their "neutral" r and v alleles. Asymmetry between R and V genes lies in the fact that the strains homozygous for the R genes are the only strains that cannot grow. From these results it is postulated that the V-gene product is a diffusible cytoplasmic factor and that the R-gene product, which is nonautonomous, is a ribosomal component.

Alleles↗