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G Cathomas

Publications and source records attributed to G Cathomas.

65 records · Page 4Linked to original sources
PubMed1991

Differences in the action and metabolism between retinol and retinoic acid in B lymphocytes.

We have previously reported on the dependency of activated B lymphocytes for retinol. Here we confirm and extend these findings that cells deprived of retinol perish in cell culture within days, displaying neither signs of apoptosis nor of cell cycle arrest. Cell death can be prevented by physiological concentrations of retinol and retinal, but not by retinoic acid or three synthetic retinoic acid analogues. To exclude the possibility that retinoic acid is so rapidly degraded as to escape detection, we have tested its stability in intra- and extracellular compartments. Contrary to expectation, we find that retinoic acid persists for longer (t 1/2 3 d) in cultures than retinol (t 1/2 1 d). Furthermore, despite the use of sensitive trace-labeling techniques, we cannot detect retinoic acid or 3,4-didehydroretinoic acid among retinol metabolites. However, retinol is converted into several new retinoids, one of which has the ability to sustain B cell growth in the absence of an external source of retinol, supporting the notion of a second retinol pathway. We have also determined which of the known retinoid-binding proteins are expressed in B lymphoblastoid cells. According to results obtained with polymerase chain reaction-assisted mRNA detection, they transcribe the genes for cellular retinol- and cellular retinoic acid-binding proteins, for the nuclear retinoic acid receptors, RAR-alpha, -gamma, and RXR-alpha, but not RAR-beta. Our findings that B cells do not synthesize retinoic acid or respond to exogenous retinoic acid on the one hand, but on the other hand convert retinol to a novel bioactive form of retinol, suggest the existence of a second retinoid pathway, distinct from that of retinoic acids.

B-Lymphocytes↗
PubMed1989

[HIV infection caused by kidney transplant: case report and review of 18 published cases].

Since 1985 organ donors are routinely tested for the presence of HIV-antibodies, but prior to that time several patients acquired HIV-infection from grafts. In May 1984 a 65-year-old woman on hemodialysis received a cadaver kidney graft from a young iv drug addict. The transplant functioned perfectly with cyclosporin A immunosuppression. Retrospectively, 22 days after surgery HIV antigen was detected. At this time only a faint band of anti-p24 antibodies was found in the Western blot. Two years after surgery splenomegaly was found in the apparently healthy patient. During the third year thrombocytes fell and she developed lymphadenopathy and constitutional symptoms. Up to this time the immunological parameters were in the range of 10 healthy renal transplant patients with cyclosporin A treatment. In the 4th year T-lymphocytes dropped to values below 200 and the patient developed Pneumocystis carinii pneumonia. A few months later a pulmonary node, which later proved to be a B-cell lymphoma, appeared. Slightly less than 5 years after transplantation the patient died from clinically diagnosed pulmonary embolism. The progression of the HIV-Infection in this patient and in one of 18 patients in published reports show that the incubation period is several years shorter in renal transplant patients than in those who acquire HIV from blood products.

AIDS Serodiagnosis↗
PubMed1989

[Cytomegalovirus diagnosis in immunocompromised patients: detection of early viral protein and viral nucleic acids in shell vial culture].

Conventional cell culture often requires several weeks for the detection of cytomegalovirus and is therefore an inappropriate technique for the rapid diagnosis of cytomegalovirus infections. Serology is not useful in the immunocompromised patient. We describe our experience with a rapid method for the detection of cytomegalovirus in known positive materials and in clinical specimens from immunocompromised patients. For this procedure the specimens were centrifuged onto cell monolayers. One day after infection early protein was detected by immunofluorescence, and in duplicate cultures viral DNA was detected by in situ hybridization after 5 days. Cytomegalovirus was found most often in urine and bronchoalveolar lavage, but less frequently (and to a lesser extent) in blood and saliva. No virus was found in stool and CSF. Cytomegalovirus was diagnosed only in 51.4% by the detection of early protein, whereas in situ hybridization detected cytomegalovirus in 93.1% of the specimens. For the diagnosis of cytomegalovirus we recommend the shell vial cell culture technique, followed by the detection of early proteins after 24 hours and in situ hybridization after 5 days.

Cytomegalovirus↗
PubMed1988

[Chlamydia diagnosis in clinical practice. Chlamydia trachomatis EIA and direct immunofluorescence (MikroTak) in comparison with cell culture].

The correct obtaining of material is decisive for microbiological diagnosis. The new immunologic methods, enzyme immunoassay (Chlamydiazyme) and the direct immunofluorescence with monoclonal antibodies (MikroTrak) for the detection of Chlamydia trachomatis have several advantages over cell culture. In 457 tests of urethral smears from men with all 3 methods, sensitivity and specificity were compared with cell cultures as method of reference. Tests with Chlamydiazyme yielded a concordance of 87.1%, a sensitivity of 81.5% and an specificity of 87.8%. Tests with MikroTrak were almost identical with a concordance of 86.9%, a sensitivity of 81.3% and a specificity of 87.5%. With both methods, the positive predictive value with 43.8% and 43.3% respectively is low. Frequent positive results with the immunological methods, which could not be verified by cell cultures, must be interpreted as failure of the culture method under practice conditions. The correlation of results with the clinical course supports this assumption.

Adult↗
PubMed1988

Oral hairy leukoplakia in a HIV-negative renal transplant patient: a marker for immunosuppression?

We report the case of a 58-year-old renal transplant patient who developed oral hairy leukoplakia. Examination for HIV-1 and HIV-2 infection was negative. Biopsy of the lateral tongue showed ballooned prickle cells and electron microscopy revealed herpes-type viruses. In situ hybridization and examinations with the Southern blot technique yielded Epstein-Barr virus. Serology for Epstein-Barr virus was reactive. Immunological investigation of the patient showed a marked decrease of T-helper and T-suppressor cells as the result of immunosuppressive regimen. Oral hairy leukoplakia may be a marker for severe immunosuppression but is not necessarily associated with HIV infection.

Female↗