The oncornaviruses share several biological, biochemical, and structural properties that distinguish them from other RNA viruses. Rous sarcoma virus, a representative of avian oncornaviruses, manifests two major functions: cell transformation and virus replication. Both functions are independent, and are expressed separately in defective viruses. The virus has a 60-70S RNA, composed of 35 S subunits. It appears that each subunit of viral RNA carries the same genetic information and, furthermore, that 10% of this information is coding for cell transformation. Without this 10% the virus can still replicate. The RNA genome is expressed when the virus penetrates a sensitive cell, provided the virus carries an active reverse transcriptase. Virus-transformed cells possess a DNA form of the viral genome. The viral DNA is infectious, and can lead, upon transfection of permissive cells, to the production of a new viral progeny. We have established that the minimum molecular weight of the viral DNA is 6 X 10(6) daltons, and that this DNA is covalently bound to the chromosomal DNA. Also by examining the frequency of transfection events in the DNA-treated cells we suggest that transfection is a single-hit phenomenon. It follows that viral DNA of 6 X 10(6) daltons carries all the genetic information to code for the virus production. It seems likely that the transfection mechanism giving rise to transforming viruses is different from that producing nontransforming segments. In general terms, the experimental data indicate that certain RNAs and DNAs could accomplish malignant transformation if they are able to penetrate into the cell and give rise to the DNA forms which could be integrated into the cellular genome.

Animals↗

PubMedDate not supplied

[Recent progress made in the classification of lymphoid and monocytoid leukemias and of lympho- and reticulo-sarcomas].

New methods helpful in the classification of lymphoid and monocytoid leukaemias and haematosarcomas have recently become available. Among the most valuable procedures have been those detecting immunological markers and the ultrastructural analysis permitted by convention and scanning electron microscopy. The results of these studies, taken together with a meticulous morphologic examination on Giemsa smears allow a more subtle classification on these neoplasias. Among the most interesting points, one can list: a) The description of macroglobulinemic proplasmocytic leukaemia; b) The observation that all the prognostic parameters in the four types of common acute lymphoid leukaemia (ALL) (prolymphocytic, microlymphocytic, macrolymphocytic, prolymphoblastic) such as age, tumour mass (or leucocytosis are related to the cytological type); T marker may be found in all these types, except for the prolymphoblastic one; c) T or B immunoblastic acute lymphoid leukaemias have been described as a fifth type of ALL; d) The lymphosarcomas which can be histologically nodular (composed of B cells) or diffuse (composed of cells presenting B, T or no markers) can be cytologically prolymphocytic or lymphoblastic (or lymphoblastoid) if they are nodular, prolymphocytic, lymphoblastic, or immunoblastic if they are diffuse; true (African) Burkitt's lymphosarcomas (BLS) must be distinguished from all the pseudo (non-African) Burkitt's lymphosarcomas which have been described elsewhere and which are either immunoblastic or lymphoblastic (oid) lymphosarcomas with a few macrophages; e) The diagnosis of reticulosarcoma which was in the past abusively carried out (because of confusion with immunoblastic lymphosarcoma) is based on the presence of many reticluins fibers at histological examination and on the cytological aspect of the cells on smears (the distinction of those cells with immunoblasts is easy).

B-Lymphocytes↗

PubMedDate not supplied

[Non-Hodgkin hematosarcomas. Classification of the Reference Center of the World Health Organization (WHO)].

At the request of the Leukaemia and Haematosarcoma Reference Centre of the World Health Organisation (W.H.O.), one of the authors (G.M.) has suggested a classification taking into account the most recent knowledge and all parameters (histological, cytological and immunological) necessary for the categorisation of non-Hodgkin's haematosarcomas. He has employed traditional terminology, thereby avoiding the jargon used by certain authors which is not justified in the light of modern scientific knowledge which, more than ever, merits the use of classical terminology. The authors present this W.H.O. classification for the first time to the french press. The reader will find familiar terms such as "lymphosarcoma", which may take a nodular or diffuse form (in the second case the recently identified immunoblastic form is introduced and mycosis fungoides is placed in the category) and reticulosarcoma. Microscopic typing of a haematosarcoma is essential since the various types differe considerably in their sensitivity to treatment with a corresponding difference in the chance of cure. The potential for cure is also dependent upon the topographic stage which should be determined by a series of routine step which may still be recommended today but which may be useless in the future by virtue of the frequency of disseminated forms in relation to localized forms, and of the remarkable effectiveness and constant progress of chemotherapy and immunotherapy.

B-Lymphocytes↗