[Physicians and the danger of nuclear war]. / Les médecins et le danger de guerre nucléaire.

International Physicians for the Prevention of Nuclear War (IPPNW), the 1985 Nobel Peace Prize winners, are active in some sixty different countries. Their action is based on the outlook that any nuclear war would cause not only millions of deaths, but also millions of severely injured or burnt victims for whom the medical profession, decimated as well, would be most helpless. They strive to obtain that governments, in agreement with treaties that almost all countries have signed, ascertain that nuclear weapons, which are internationally illegal, be globally abolished. The impact on political authorities would undoubtedly be reinforced if the number of physicians supporting the action of IPPNW was increased.

Wars of the 1990s.

The 40 wars of the past decade, all 'minor', have resulted in a total of more than two million deaths and 20 million refugees or displaced persons. Few have been the international wars typical of previous periods. Nine out of ten began as internal or civil wars, foreign intervention--when it occurred--being always secondary. The weapons used, the effects on the civilian populations, the type and extension of damages are different but equally destructive. The main causes of these conflicts are cultural or religious, rather than economic. The best attitudes to attempt to prevent or stop them are surveyed.

[Nuclear arms and medical responsibility]. / Armes nucléaires et responsabilités médicales.

The medical profession would be unable to cope with the millions of simultaneous casualities of a nuclear war. Such a war between developed countries becomes less likely, but new countries equip themselves, with nuclear weapons, using the violation of the Non-Proliferation Treaty by the great powers as an excuse. The danger of nuclear war is spreading with the consequences one can imagine. A world movement, including military experts, political, moral and scientific leaders and representative national medical groups, among them the World Medical Association, press governments to negotiate a comprehensive abolition treaty. The "Académie royale de Médecine de Belgique" joining moral prestige to an authoritative expertise, should take a stand on the problem.

[Analysis by computer simulation of cell kinetics of the liver]. / Analyse par simulation sur ordinateur de la cinétique cellulaire du foie.

A computer simulation model of cell kinetics is established to represent the variations of rat hepatocyte populations in several circumstances: normal growth, circadian rythms, response to partial hepatectomy under different conditions. This model differs from usual mathematical models-sets of equations--by the use of digital simulation techniques. Each cell in the population is represented by a set of variables in the computer memory. When experiments are simulated, the values of these variables are modified step by step according to the hypotheses we want to test. Counts and statistics derived at each step from the simulation are then compared to experimental values, in order to assess the validity of our hypotheses. This procedure enables us to establish a minimal set of conditions and outside causal effects necessary to mimic the behaviour of the liver under experimental situations similar to those we simulate. Such modelisation suggests further work on the mechanisms governing cell kinetics in the normal liver and during cancerisation.

Student population changes and progress in Belgian medical schools.

The present study was designed to analyse the evolution of student populations--undergraduates and graduates--in the 11 Belgian medical schools from 1969 to 1982. During this period, an overall 44% drop in the number of entrants was observed, while the number of medical graduates continued to rise until 1977, when it stabilized. French- and Flemish-speaking universities followed a similar trend. During the period under study, the proportion of women students virtually doubled from 25 to 44%. The total success rate averaged 39% for Belgian students and 24% for foreigners. By comparing success curves over the years, the various medical faculties were rated with a 'selectivity' score, indicating those significantly different from the national average. A separate classification was made for preclinical (3 years of 'Candidature') and clinical (4 years of 'Doctorat') phases since, among the 11 Belgian medical schools, four teach only preclinical subjects. Marked differences in failure rates were observed between candidature and doctoral education even within universities.

[Monoclonal antibodies inhibiting the function of a murine cytotoxic T lymphoma]. / Anticorps monoclonaux inhibiteurs de la fonction d'un lymphome murin T cytotoxique.

The thymic lymphoma NS8, obtained by infection of murine antigen-primed lymphocytes with the Radiation Leukemia Virus (RadLV) exhibits a cytotoxic function specific for the sarcoma target T2. We have immunized LOU rats with cells from this cytotoxic T lymphoma and fused their splenocytes with cells from the LOU rat myeloma IR983F to obtain hybridomas. Monoclonal antibodies produced by the 1G hybridoma recognize structures on the surface of NS8 cells. Moreover they are able to inhibit the expression of the specific cytotoxicity mediated by NS8 cells. In contrast, the cytolytic activity of a MLC is not affected by these monoclonal antibodies.

Measurements of cell-mediated cytotoxicity on target cells labelled with the indium-111-oxine complex.

The preparation is given of an 111indium-oxine complex that is non toxic and can label reproductively various types of cells. They retain the label for long periods (24 hours and more). This method gives parallel results for cell-mediated cytotoxicity measurements to Chromium-51 labelling and is found to have wider uses. It can label cells that release 51Cr too fast, makes possible long term measurements of cytotoxicity and accurate counts on small numbers of target cells.

[Method of efficacious immunization against syngeneic murine sarcoma]. / Mise au point d'une procédure d'immunisation efficace contre un sarcome murin syngénique.

C57BL mice are immunized by subcutaneous injection of the T2 syngeneic tumour (MCA fibrosarcoma), followed a week later by surgical removal of the tumour. Such mice can be made hyper-immune by challenging them with mitomycin C-treated T2 cells and they do not develop a tumour after a subsequent inoculum of live T2 cells. Lymph nodes near the site of tumour inoculation are removed after 2 weeks and histological studies show an increase in the number of macrophages and mast cells but not of Lyt-2+ lymphocytes.

[Changes in the vitro membrane potential of cancer cells induced by contact with cytotoxic lymphoid cells]. / Modifications du potentiel de membrane de cellules cancéreuses in vitro sous l'influence du contact de cellules lymphoïdes cytotoxiques.

Plasma membrane potentials have been measured in a cancer cell line at different stages of growth. A chamber has been especially built for pH control of the culture medium during several hours. Individual values spread widely from 14 to 44 mV but low measurements are less frequent after 3 days of culture when the growth rate is at a peak. The same cancer line is grafted serially in syngeneic C 57 bl mice were it induces an immunological sensitization of the lymphnode cells. The effect of such cytotoxic lymphocytes on the membrane potentials of the target tumour cell has been studied after a contact (15 to 90 minutes) too short for any morphological changes to be detectable. There is a decrease in the mean values and a very significant rise in percentage of measurements below 20 mV. No such changes are observed in control experiments where naïve lymphocytes are used. These results are discussed in relation to the hypothesis of an increased permeability of the plasma membrane to ions as an early event in cell mediated cytotoxicity.

[Immunity and cancer: suppressor effect on the cytotoxic activity of lymphoid cells from animals carrying syngeneic tumors]. / Immunité et cancer: effet suppresseur sur l'activité cytotoxique des cellules lymphoïdes d'animaux porteurs de tumeurs syngénéiques.

When it is tested in vitro, the cytotoxic action of lymphocytes from mice bearing a syngeneic tumour (T2) vary with the age of the graft. At a time when it is very low, the lymphoid cells are cultivated for 3 days and then can be fractionated in two subpopulations on a glass bead column: a cytotoxic "non adherent" group of cells and an "adherent" group that inhibits the activity of the first group when it is added to it.

[Chronic atrophying polychondritis]. / La polychondrite chronique atrophiante.

A case of chronic atrophic polychondritis in a 75 year old female patient is reported. The disease started with an asymptomatic lesion of the nasal septum. It was diagnosed after involvement of the auricular cartilages, which was followed by an ocular and then by a tracheal symptomatology. A histological study by means of optical microscopy and of electronic microscopy is presented. The general characteristics of chronic atrophic polychondritis are given. It is a systemic, inflammatory disease, and progresses by successive outbreaks. Its gravity lies in the frequency of laryngeal and tracheo-bronchial lesions. Its pathogeny is unknown. Two hypotheses are considered: the first, that it is due to a disturbance in the metabolism of mucopolysaccharides ; the second is based on an immunological mechanism.

Inhibition by lymphoid cellular factors of the immunological cytotoxicity against a syngeneic tumour.

Lymphoid cells of C57BL mice bearing a syngeneic sarcoma are cytotoxic against the same tumour cells in vitro at two different periods of the growth of the tumour separated by a "mute period". Without additional antigenic stimulation the lymphoid cells from the "mute period" can be made cytotoxic by preincubation in vitro and elimination of adherent cells by a passage through a glass bead column. Either of these treatments alone is inefficient. The cytotoxicity revealed in this way is due to cells with different properties than those that are directly cytotoxic during the 4th week of the tumour growth. The significance of these results is discussed. It is suggested that some other cells have to be eliminated because they compete with or inhibit the activity of the "mute period" lymphoid cells made cytotoxic by preincubation.

[Changes of lymphoid cell cytotoxicity, shown in vitro, of mice bearing a syngeneic tumor after injection of killed tumor cells]. / Modifications de la cytotoxicité manifestée in vitro par les cellules lymphoïdes de souris porteuses d'une tumeur syngénéique après l'injection de cellules tumorales tuées

Lymphoid cells from mice bearing a syngeneic tumour show a cytotoxic activity in vitro, occuring in two succesive waves. Normally inactive during the second week after grafting, lymphoid cells have a marked killing ability during this period when heavily irradiated tumour cells have been injected on the 6th day. On the contrary, the cytotoxicity due to the graft, which is important from the 20th to the 30th day, is inhibited by injection of killed tumour cells 15 days before the test. Quantitative variations of the tumour antigen liberated in the animal may be responsible for those effects.

Ultrastructural study of the relationship between immune cytotoxic lymphoid cells and target cells in vitro.

Ultrastructural details of the relationship in vitro between sensitized T lymphoid cells and YAC target cells are described. Within a few hours very close connections develop between these two cells. Narrow junctions with parallel plasma membranes and local evaginations of the lymphoid cell into recesses of the target cell are specific aspects. Very fine threadlike material is found between the two plasma membranes at the narrowest zones. The lymphoid cells concerned have an intermediate structure between ordinary small lymphocytes and blast cells. They do not seem to be modified in the process while YAC target cells are severly damaged. Polysomes are dispersed; mitochondria and rough endoplasmic reticulum are affected locally or generally. Later, nucleoli and chromatin become dense and pycnosis occurs. The significance of these results is discussed.