The estimation of numerical density in biology (proceedings).
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Biomedical subjects
Publications and source records attributed to J Boniver.
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A case of bacterial endocarditis complicated by complete auriculoventricular block is reported. The pathological findings and data from previously reported cases point to the fact that this complication is generally indication of very extensive cardiac and valvular damage. Surgery, although dangerous, should be attempted in the circumstances.
During the recovery period following a sublethal irradiation, lymphoid-like cells accumulate in the bone marrow of the mouse. Among these cells, a peculiar element called 'X cell' has been previously described. Its morphological aspects are different from the precursors of the various hemopoietic lines. The 'X cell' could be an ancestral element normally repressed in the adult marrow. The aim of the present work is to determine whether this peculiar element can be detected in the bone marrow of young mice during the first month of life. The myelograms showed that on the day of birth, the marrow was almost exclusively composed of erythrocytic cells. During the postnatal period up to day 20, there was a progressive increase of granulocytic cells. The percentage of lymphoid-like cells increased from 5 per cent at birth to 28 per cent on day 20. The absolute number of these elements, calculated from the percentages obtained on the myelograms and from the number of nucleated cells per two femurs, increased from 20,000 at birth to 7,000,000 at day 30. The ultrastructural analysis demonstrated that the lymphoid-like population was composed of small lymphocytes, lymphoblasts and X cells, the proportions of which varied in relation to the age of the animals. X cells and lymphoblasts were found to be especially numerous around the 4th or 5th day, whereas the small lymphocytes were scarce.
Light and electron microscopical studies demonstrate that regional but also non-regional lymph nodes of C57BL mice grafted by tumours, induced by methylcholanthrene, are able to elicit a complex immunological response of the cellular, as well as of the humoral types. No significant difference was found according to the growth rate and the immunogenicity of the six tumours investigated. The cellular immunization is predominant during the two first weeks. It is mainly characterized by the appearance in the paracortical area of numerous immunoblasts which are in close connexions with'dendritic' macrophages showing multiple long cytoplasmic expansions. During the same period of time, the reticulum cells become hyperplasic in the sinus. From the 15th day to the death of the animals, the cellular immunizaiton progressively regresses while a humoral immunity develops. It shows itself as an hypertrophy of the lymph follicles and an increase in the number of medullary cord plasma cells.
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The distribution and concentrations of the basement membrane proteins laminin and type IV collagen were studied in isolated placental villi in normal pregnancy and in pre-eclampsia. In both cases these proteins could be localized by immunofluorescence in the trophoblast and capillary basement membranes, and occasionally also in the matrix surrounding the capillaries. The basement membrane proteins were quantified by solubilizing the villi with proteolytic enzymes and by subsequently measuring the concentrations of two resistant domains of these proteins (7-S collagen and the fragment PI, representing type IV collagen and laminin, respectively) with specific radioimmunoassays. The ratio type IV collagen:laminin was significantly higher in pre-eclamptic samples than in the controls, most probably reflecting a decrease in laminin concentration in the villi in pre-eclampsia. Such a change in the chemical composition of placental basement membranes could weaken the attachment of trophoblast cells to the underlying basement membrane and also modify the permeability and exchange properties of the villi.
The dual physiological role of the thymus in T cell positive and negative selection appears prominent in the establishment of appropriate host immune defenses. However, the cellular and molecular mechanisms underlying those thymic functions begin only to be understood. On the basis of our previous investigations about the thymic expression of different neuroendocrine-related signals, we have advanced a model which transposes at the peptide level the intervention of this primary lymphoid organ in both T cell positive and negative selective processes. There is now ample evidence that the thymic subcapsular and medullary epithelium is the site for synthesis of neurohypophysial (NHP)-related peptides (reviewed in Geenen et al., 1992a). We have also demonstrated that the epithelial component of thymic "nurse" cells (TNC) synthesizes NHP-related peptides and expresses a neuroendocrine-like phenotype (Geenen et al., 1988a). This observation was a remarkable example of the intimate neuroendocrine-immune interactions that take place during T cell ontogeny. Further immunocytochemical analyses have confirmed that one dominant NHP-related epitope belongs to the oxytocin (OT) lineage of the NHP peptide superfamily (Robert et al., 1991, 1992). The intrathymic coexpression of this OT-like epitope with a neurophysin protein domain is a strong argument for a local synthetic process similar to the hypothalamo-NHP one. However, the absence of ir-OT in secretory granules of thymic epithelial cells (TEC), as well as of NHP-related peptides in the supernatant of TEC cultures questioned the application to the thymus of the classical neurosecretory model established for hypothalamic magnocellular neurons (Scharrer & Scharrer, 1944).(ABSTRACT TRUNCATED AT 250 WORDS)
Autoimmune pancreatitis has been characterised in 1995, but only a few cases have been published since then, most of them from Japan. This report describes the cases of two Belgian male patients who presented with isolated obstructive jaundice. Radiological imaging studies were highly suggestive of carcinoma of the head of pancreas and both patients underwent uneventful cephalic pancreaticoduodenectomy with portal vein resection. Pathological analysis of the removed tissues suggested an autoimmune process in both cases. Both patients had hyper-gammaglobulinemia and antinuclear antibodies, but failed to show evidence of any other autoimmune disease or cause of chronic pancreatitis. In both cases final diagnosis was autoimmune pancreatitis. Preoperative clinical suspicion of this diagnosis is mandatory and may avoid unnecessary surgery in future cases.
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We report herein the case of a Belgian 76-year-old woman who developed a hepatic tumour suspected to be a breast cancer metastasis. Radiological imaging and guided biopsies were not contributive. The patient underwent an explorative laparoscopy with frozen sections that did not provide further diagnosis, and an open left bisegmentectomy was performed during the same anaesthesia. Histopathological examination of the hepatic mass showed Echinococcus multilocularis metacestodes, demonstrating alveolar echinococcosis. As our patient denied any travel in foreign countries and has undergone regular abdominal ultrasonographies since her mastectomy, it is highly likely that this alveolar echinococcosis had been contracted in Belgium. If some imported cases may be seldom managed in Belgium, to our knowledge, this case is the first occurrence of alveolar echinococcosis contracted in Belgium. This report, added to the demonstration of E. multilocaris infection of 50% of red foxes in Southern Belgium, and the potential infection of domestic cats and dogs, should attract attention of the medical community on the possible outbreak of endemic alveolar echinococcosis in Belgium, and on the related public health concerns.
Owing to the establishment of a procedure aiming at a reduction of the medical supply (numerus clausus), the French Community of Belgium had decided to introduce, at the end of the third year of medical studies (third candidature), a procedure of selective attribution of the certificate allowing for a unlimited medical practice. We assessed the predictive value of the results obtained during and at the end of the first candidature (first year of medicine) for the attribution of this certificate. We studied the results of the 225 students enrolled in the first candidature in medicine at the University of Liège during the academic year 1997-1998, and we correlated them to the subsequent attribution (1999-2000- and 2000-2001) of the certificate. The success of the first candidature in the first or second session is an important predicting factor towards the reception of the certificate. A non-authorization to continue the studies in medicine in case of failure in the first session or a non-authorization to repeat the first candidature in case of failure in the second session would have, respectively, a negative predictive value (NPV) of 91.9% and 97.4% and would allow to restream 111 students at the end of the first session or 39 students at the end of the first candidature. The results of the preliminary assessments mode during the month of January are also highly predictive of the chances to get the certificate. Among the 160 students who have not successfully passed a minimum of 3 exams, only 14 students obtained the certificate. The restreaming of those students would correspond to a NPV of 91.2%. Students who were not successful in a minimum of 2 exams would have less than 5% chance to obtain the certificate. In this case, 109 students would be restreamed (NPV = 95.4%). In conclusion, the selection of the students who will obtain, at the end of the third year of medicine, the certificate allowing them for an unlimited medical practice is obtained, in a large proportion, during the first candidature and especially after the session of January. In view of those results and considering the decree abolishing the selection at the end of the third year of medical studies, one could argue about the appropriateness of the current procedure, chosen by the French Community of Belgium, compared to other solutions prioritising an earlier selection of the future doctors.
Idiopathic pulmonary fibrosis and pulmonary fibrosis associated with systemic diseases are the most frequent diffuse interstitial pulmonary diseases. They slowly but irrevocably progress towards terminal respiratory failure. They can also be complicated by severe acute respiratory failure and admission in the intensive care unit can be discussed. Despite invasive mechanical ventilation, anti-infectious and immunosuppressive treatments, the disease carries a high mortality rate. We report and discuss the case of a patient with idiopathic, pulmonary fibrosis (UIP) who underwent rapid clinical deterioration.