Biomedical subjects
G Dreyfuss
Publications and source records attributed to G Dreyfuss.
[Demonstration of the antifilarial activity of fosfomycin on the filaria Dipetalonema dessetae, Bain, in the rodent Proechimys oris, Thomas].
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Messenger RNA is translated when associated with the cytoskeletal framework in normal and VSV-infected HeLa cells.
When the cytoskeletal framework is prepared from suspension-grown HeLa by extraction with nonionic detergent, all the polyribosomes are associated with the framework while 80% of tRNA and the major portion of monoribosomes as well as 75% of the cell proteins are found in the soluble fraction. The mRNA of polyribosomes is bound to the cytoskeleton and these molecules remain attached even after polyribosomes are disassembled in vivo prior to extraction. Although all actively translating message molecules are attached to the framework, about one quarter of the poly(A)+ mRNA is free of the framework. The binding of message to the skeleton may be obligatory for translation. Upon infection with VSV, all the viral polyribosomes but not all the viral messages of the infected cell are associated with the cytoskeletal framework. Pulse-chase labeling shows that VSV messages initially associate with the framework and then later detach and cease translation. The mRNA for the viral glycoprotein (G), known to translate only on ribosomes bound to endoplasmic reticulum, is also retained by the detergent-extracted structure. It appears that the protein substructure of the endoplasmic reticulum which binds polyribosomes is a component of the cytoskeletal framework.
Localization of the Abelson murine leukemia virus protein in a detergent-insoluble subcellular matrix: architecture of the protein.
We examined the interaction of Abelson murine leukemia virus protein P120 with other cellular components after extraction with the nonionic detergent Triton X-100. Most of the Abelson murine leukemia virus P120-associated kinase activity was found in the detergent-insoluble matrix in both lymphoid and fibroblast cell lines. The P120 labeled during a short exposure of cells to [35S]-methionine was mainly in the detergent-insoluble matrix (lymphoid cells) or equally distributed in the detergent-insoluble matrix and the soluble fraction (fibroblasts). Steady-state-labeled P120 was distributed equally in the two fractions (lymphoid cells) or mostly in the soluble portion (fibroblasts). Thus, there was an apparent movement of P120 from the detergent-insoluble matrix to the detergent-soluble fraction and a concomitant loss of enzymatic activity. When the detergent-insoluble matrix was incubated with [32P]ATP in situ, phosphorylation of tyrosine residues of P120 was observed. We found an 80,000-molecular-weight fragment of P120 (designated F80) after extraction of fibroblast cells with detergent. F80 was not found in extracted lymphoid cells, but mixing labeled lymphoid cells and unlabeled fibroblasts before extraction produced the fragment. F80 contained the gag determinants of P120 but did not react with Abelson-specific serum. These data allowed us to assign various features of the protein to regions of the P120 molecule and to localize the Abelson-specific antigenic determinants to the C-terminal region of the molecule.
Association of the src gene product of Rous sarcoma virus with cytoskeletal structures of chicken embryo fibroblasts.
We have prepared cytoskeletons from normal and Rous sarcoma virus-transformed cells by extraction with nonionic detergents in a buffered salt solution designed to preserve the structure as it exists in vivo. Virtually all of the phosphoprotein pp60src in the cell is bound to such cytoskeletons. Furthermore, when these cytoskeletons are incubated in situ with [gamma-32P]ATP, pp60src is phosphorylated. Labeling of other apparently transformation-specific cytoskeletons phosphoproteins is also observed. These results directly demonstrate an association between pp60src and elements of the cytoskeleton and suggest that pp60src may exert at least some of its effects as a consequence of its interaction with this cellular framework.
[3-Aminoquinuclidine carbamates, ureas, thio-ureas derivatives with potential parasiticidal activity (author's transl)].
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Compartmentalization of cyclic AMP-dependent protein kinases in human erythrocytes.
The human erythrocyte contains two types of cyclic AMP-dependent protein kinase. The membrane-associated protein kinase holoenzyme can be released intact by hypotonic treatment at alkaline pH. Chromatography on DEAE-cellulose and molecular weight determinations demonstrate that this enzyme is a type I cyclic AMP-dependent protein kinase, while the predominant cyclic AMP-dependent protein kinase found in the cytoplasm is type II. The catalytic subunits of the two types of kinase found in the erythrocyte are identical, but the regulatory subunits, which distinguish the two types of kinase, determine their localization within the cell. It is proposed that the regulatory subunit of the type I enzyme, in addition to binding the catalytic subunit, interacts specifically with one or more membrane proteins and that this interaction may serve to position the kinase in preferential proximity to protein substrates.
Fluorescent photoaffinity labeling: adenosine 3',5'-cyclic monophosphate receptor sites.
An approach to the study of protein receptor sites in protein mixtures or supramolecular assemblies by using fluorescence spectroscopy is described. This approach, fluorescent photoaffinity labeling, combines the merits of photoaffinity labeling to attain site-directed reactivity with the probing power of fluorescent ligands. A fluorescent photoaffinity label for cyclic AMP receptor sites of cyclic AMP-dependent protein kinases was synthesized in both unlabeled and radioactive forms. The probe, 8-azido-1,N(6)-ethenoadenosine 3',5'-cyclic monophosphate, mimics cyclic AMP in its ability to stimulate the phosphotransferase activity of the protein kinases and strongly competes with cyclic AMP for its binding sites in all preparations so far tested. Photolysis, after equilibration of protein kinase and 8-azido-1,N(6)-ethenoadenosine 3',5'-cyclic monophosphate in the dark, effects binding of the intermediate nitrene irreversibly and specifically to the cyclic AMP sites with the development of fluorescence. Excess reagent and low molecular weight photolytic products are removable by dialysis. Studies of a crude beef heart preparation containing cyclic AMP-dependent protein kinase suggest that the cyclic AMP binding sites are hydrophobic in nature and strongly immobilize the adenine moiety of the cyclic nucleotide.
[Control of diabetes by diet alone in patients receiving oral hypoglycemic drugs].
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Polyamine excretion in the urine of cancer patients.
In the human body, the production of three polyamines--putrescine, spermidine and spermine--is largely associated with tissue growth, while that of a fourth--cadaverine--seems to be the result of bacterial action. In 37 (88%) of 42 cancer patients and in 24 (44%) of 54 patients with various nonmalignant diseases, increased amounts of polyamines were found in the urine. In the nonmalignant group, which served as a control group, the increased polyamine excretion was especially evident in patients with infections. There were, however, differences in the excretion patterns of the cancer and control groups: combinations of elevated levels of putrescine, spermidine and spermine were seen exclusively in the cancer patients; spermine was not found in the urine of women in the control group. The determination of urinary polyamines appears to hold promise as an aid in the diagnosis of malignant disease and in following up the results of therapy.
Determination of polyamines in urine.
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An unusual trabecular thyroid cancer producing calcitonin.
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Infection of Lymnaea truncatula and Lymnaea glabra by Fasciola hepatica and Paramphistomum daubneyi in farms of central France.
Natural infection of Lymnaea glabra and Lymnaea truncatula by Fasciola hepatica and/or Paramphistomum daubneyi was studied at two periods of risk (June-July and September-October) in 11 French farms known for their high prevalences of F. hepatica infection in ruminants. A total of 1,778 L. truncatula and 2,396 L. glabra measuring 6 mm or more in height were collected to determine the prevalence of natural infection with F. hepatica and P. daubneyi. The role of four factors, i.e. season, snail co-infection (F. hepatica-P. daubneyi), ruminant host and the existence of single or mixed intermediate host communities, was investigated. There were no differences in prevalences between the two risk periods. Co-infections in L. glabra were more frequent than expected. The prevalences of infection with F. hepatica or P. daubneyi in L. glabra were higher in farms rearing sheep than in farms rearing cattle. A similar finding was also noted for L. truncatula infected with P. daubneyi only. L. glabra was a much better intermediate host for F. hepatica and P. daubneyi when it was the only available snail, possibly indicating an adaptation of parasites to their less usual host in local conditions. The two trematodes preferably developed in L. truncatula rather than in L. glabra when both host species lived in the same places.
[Dipetalonema dessetae in Proechimys oris. II. Evaluation of the model for pharmacologic investigations of antifilarial chemotherapy (author's transl)].
Dipetalonema dessetae in Proechimys oris is a new model of rodent feafilariasis with several interesting features with respect to its utilisation in antifilarial pharmacology. 1. In the first part of these studies, it has been shown that the final host of the filaria, a rodent, was easy to breed. A prolific mosquito Aedes aegypti was an effective vector, and with the selected mode of infection i.e. 200 infesting larvae subcutaneously injected, 80% of the rodents were infected. 2. From 90 to 150 days p.i., the microfilaria count increased and reach a plateau which was maintained during 60 days. This plateau has enabled the evaluation of microfilaricidal activity. A drug exhibited a significative (0,10) microfilaricidal activity in two animals if the microfilaremia were reduced to 87% and 83,6% of pretreatment values, two or six weeks after treatment. 3. Identically, a compound would present a significative (0,12) macrofilaricidal effect if not a single male and not more than 1,6 female filaria were found at the autopsy of both animals six weeks after treatment. Activity on immature worms (3rd and 4th instar larvae, young adults) was qualitatively evaluated by the presence or absence of filaria at the autopsy of rodents which have been treated at various dates depending of the stages. 4. The sensitivity of this model was evaluated with several known antifilarial drugs, some of them unused by human patients. Diethylcarbamazine, levamisole, suramin, mebendazole and flubendazole killed adults, microfilariae and infesting larvae. Mel W was mainly macrofilaricidal and trichlorfon active on mf. Among all laboratory filariae, D. dessetae in P. oris is one of the most sensitive rodent models and, as such, would serve for the primary screening of new chemical compounds and for the pharmacological studies of antifilarial drugs.