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Biomedical subjects

F Robert

Publications and source records attributed to F Robert.

At least 127 records · Page 7Linked to original sources
PubMed1991

Colocalization of immunoreactive oxytocin, vasopressin and interleukin-1 in human thymic epithelial neuroendocrine cells.

Monoclonal antibodies to oxytocin (OT) and vasopressin (VP) revealed some positively staining stromal cells in the subcapsular cortex and in the medulla of the human thymus. We further demonstrated that these cells are a subset of epithelial endocrine cells and also contain immunoreactive interleukin-1 together with the neuropeptides. In addition, the thymic cells stained by monoclonal antibodies directed to the cyclic part of oxytocin or vasopressin also contained some immunoreactive neurophysins. These data support the concept of intrathymic synthesis of neurohypophyseal-like peptides fitting the hypothalamic model. However, we observed that, contrary to the situation in the brain, OT- and VP-like peptides colocalized in the same thymic cells. Furthermore, one monoclonal antibody, specific for the tail part of oxytocin, did not label thymic cells. Therefore, thymic neuropeptide(s) could be related to, but distinct from, authentic OT and VP. These observations suggest some molecular differences between hypothalamic and thymic oxytocin biosynthetic pathways which need to be further investigated.

Antibodies, Monoclonal↗
PubMed1991

Cushing's disease: a correlation of radiological, surgical and pathological findings with therapeutic results.

From 1963 to 1990 78 successive patients with pituitary-dependent cortisol hypersecretion were submitted to transsphenoidal surgery. In 57 patients, a selective adenomectomy was performed. Sixteen other patients had a central hypophysectomy. Total hypophysectomy was done nine times: in five new patients and in four patients previously operated by us. Fifty-six tumors were studied in pathology. Fifty tumors were microadenomas with ten of these measuring less than 1 mm. The tumors consisted of basophilic cells giving a positive immunostaining for ACTH. Electron microscopy on 35 tumors was characteristic with perinuclear bundles of microfilaments and often large lipid vacuoles. We did not find ACTH cell hyperplasia in the pituitary gland around tumors or in specimens of central or total hypophysectomy. Adequate follow-up was obtained on 49 patients who had been cured with an average length of 6.4 years after surgery. Our longest sustained remission following selective adenomectomy is eighteen years. Surgical cure rate was 82% for microadenomas and 81% for all intrasellar tumors. 89% of patients went into remission after total hypophysectomy but only 56% when central hypophysectomy was performed. Recurrence rate was 7.6%, occurring between three and seven years after surgery.

Adenoma↗
PubMed1991

The cycling pool of cells within human brain tumors: in situ cytokinetics using the monoclonal antibody Ki-67.

Brain tumor growth results from the relative proportion of cells contained in three populations: a) cycling/proliferative; b) quiescent (GO)/static, and c) terminally differentiated/dying. The cycling compartment can be detected by the mouse monoclonal Ki-67 antibody, an available, rapid, safe, sensitive, and specific method for immunostaining of proliferative cells. We report the Ki-67 labeling index (LI) in 48 brain tumors. Malignant brain tumors have elevated LIs, ranging from 6.0% to 56.9%: anaplastic astrocytoma, 8.0 +/- 7.3; glioblastoma multiforme, 10.1 +/- 4.2; germinoma, 11.7; medulloblastoma, 13.1 +/- 6.6; metastases, 40.3 +/- 13.1. By contrast, slow-growing tumors showed lower values (P less than .001), approaching 1%: acoustic schwannoma, 0.4 +/- 0.6; pituitary adenoma, 1.3 +/- 1.9; meningioma, 1.2 +/- 1.2; low-grade astrocytoma, less than 1; pilocytic astrocytoma, 5.6. Human brain tumors can therefore be ranked according to the percentage of cycling cells with the acoustic schwannoma among the least proliferative and the metastatic carcinoma among the most proliferative. Within a given histotype, the Ki-67 LI may have prognostic and therapeutic implications for the individual patient. Already important for neuro-oncology research, the Ki-67 labeling index should be added to the armamentarium of the clinical neuropathologist to complement the standard histopathologic diagnosis with a cytokinetic analysis of cellular proliferation.

Antibodies, Monoclonal↗
PubMed1991

The value of platelet transfusions as preparation for kidney transplantation.

The role of platelet transfusion as a preparative method for kidney transplantation is still a matter of debate. Two groups of 28 male patients transplanted between 1983 and 1988, paired for age, date of transplant, absence of anti-HLA antibody and immunosuppressive therapy have been compared. Group I was given 5 purified platelet transfusions at 1-week intervals before transplantation. Each transfusion contained 7.6 x 10(6) platelets contaminated by less than 1 leukocyte in 10(5) platelets. Group II received from 3 to 5 whole blood transfusions. In all cases it was a first transplant from cadaveric donors and previously untransfused patients before entering the protocol. No patient in group I developed cytotoxic antibodies. Acute tubular necrosis occurred with the same incidence in group I and in group II but was more severe and longer in group I, requiring hemodialysis in 62.5% and only 22% in group II. ATN was significantly associated with graft loss in group I (P less than 0.05). The total number of rejections and the number of patients undergoing rejection were not significantly different in both groups. However, the intensity of rejection was significantly higher in group I with 41% (21/51) of severe or irreversible rejections versus 9/46 (19.5%) in group II (P less than 0.05). The first rejection occurred significantly earlier in group I than in group II since 75% of the first rejection episodes occurred in the first 10 days versus 38% in group II (P less than 0.02) with a mean delay of 12.8 +/- 3.2 and 19.10 +/- 3.3 days, respectively. Although platelet transfusions are devoid of leukocytes the incidence of CMV infection was not significantly different in both groups: 57% in group I and 68% in group II. Purified platelet transfusions did not induce humoral immunization but lack of sensitization does not imply indefinite graft prolongation. Because platelets do not carry class II antigens, purified platelets transfusions represent a useful model to analyze the role of class I antigens alone in the induction of unresponsiveness in organ transplantation.

Adult↗
PubMed1991

[Capillary electrophoresis: principle and applications].

Capillary Zone Electrophoresis is a new separation technique which is performed in capillaries (ID smaller than 100 microns). The separations are carried out according to several modes which are mainly the Free Solution Capillary Electrophoresis, the Micellar Electrokinetic Capillary Chromatography and the Gel Capillary Electrophoresis. Many detection systems can be used. This technique has many advantages: high separative power, short time of analysis, low cost of operation and very low sample consumption. Capillary electrophoresis and HPLC appear to be complementary because they are based on different physical and chemical properties. Capillary electrophoresis has a great potential of applications for both chemical and biochemical analysis. This new and very efficient analytical technique is of growing interest for biochemical analysis and its use is likely to increase rapidly.

Biological Assay↗
PubMed1990

Expression of preprotachykinin-A and neuropeptide-Y messenger RNA in the thymus.

The preprotachykinin-A gene, the common gene of mRNAs encoding both substance-P (SP) and neurokinin-A (NKA), was shown to be expressed in Sprague-Dawley rat thymus by detection of specific mRNA in gel-blot analyses. In situ hybridization revealed dispersed PPT-A-labeled cells in sections from rat thymus, with a concentration of grains over a subpopulation of cells in the thymic medulla. Also, neuropeptide-Y mRNA-expressing cells were found in the rat thymus, primarily in the thymic medulla. Rat thymic extracts contained SP-like immunoreactivity (SP-LI), and the major part of the immunoreactivity coeluted with authentic SP and SP sulfoxide standards. SP-LI was also detected in human thymus, which contained between 0.09-0.88 ng SP-LI/g wet wt. Evidence for translation of preprotachykinin-A mRNA in the rat thymus was obtained from the demonstration of NKA-LI in thymic cells with an epithelial-like cell morphology. Combined with previous observations on the immunoregulatory roles of tachykinin peptides and the existence of specific receptors on immunocompetent cells, the demonstration of intrathymic synthesis of NKA suggests a role for NKA-LI peptides in T-cell differentiation in the thymus.

Animals↗
PubMed1989

Hypersecretion of gonadotropins by a pituitary adenoma: pituitary dynamic studies and treatment with bromocriptine in one patient.

Pituitary adenomas secreting gonadotropins are often diagnosed as nonsecreting tumors on the basis of clinical findings. We now describe a middle-aged woman who developed visual disturbances and was found to have a large infiltrating pituitary adenoma secreting large quantities of follicle-stimulating hormone (FSH) with moderate elevation of luteinizing hormone (LH). The patient twice underwent transsphenoidal microsurgery to partially remove the adenoma. Thereafter, a trial with bromocriptine was initiated. Normal levels of FSH and LH were observed after 6 weeks of treatment as well as improvement of visual field examination. This case illustrates the fact that some gonadotropin-secreting adenomas can be extremely sensitive to dopamine agonist adenomas can be extremely sensitive to dopamine agonist therapy.

Adenoma↗
PubMed1989

Progressive multifocal leukoencephalopathy with gray matter involvement.

An unusual case of Progressive Multifocal Leukoencephalopathy (PML) in a Haitian man with AIDS is reported. The lesions involving both white and gray matter are described radiologically and at post-mortem. The implications regarding neuroradiological differential diagnosis in AIDS as well as PML virulence in this type of patient are discussed.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Cytomegalovirus in the nervous system of patients with the acquired immune deficiency syndrome.

Clinicopathological features of infection of the nervous system by cytomegalovirus (CMV) in 31 patients with the acquired immune deficiency syndrome (AIDS) are reviewed. Neuropathology was variable, ranging from rare isolated CMV inclusions in brain without associated inflammation or necrosis, to severe necrotizing ependymitis and meningoencephalitis. In 1 patient, CMV had produced a necrotizing meningoradiculitis which presented clinically as ascending paralysis. In the brains and spinal cords of 6 patients, evidence of human immunodeficiency virus (HIV) infection of neural parenchyma was seen in close proximity to CMV infection. Both viruses individually or together were associated with low grade (microglial nodule) encephalitis. In retrospect, the diagnosis of CMV had been a difficult one to make clinically in neurologically impaired patients with AIDS. The results suggest that CMV may also localize in the nervous system without significant clinical sequelae. Imaging studies and analysis of cerebrospinal fluid revealed abnormalities in many patients, but none of them (short of culture of CMV itself in two cases) appeared to be specific to this neurological complication of the immunodeficiency.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Neuroendocrinology of the thymus.

The neuropeptides oxytocin (OT) and vasopressin (VP) are synthesized in the human thymus in a similar way as in the hypothalamo-neurophypophyseal system. Immunocytochemistry with polyclonal and monoclonal antibodies revealed that immunoreactive OT- and VP-producing cells are localized in the subcapsular cortex and medulla of human and murine thymuses. The epithelial nature of the neuroendocrine thymic cells is demonstrated by their immunostaining with a monoclonal antibody against cytokeratin. An original example of a neuroendocrine-immune microenvironment is given by the thymic nurse cells which are composed of a large neuroendocrine epithelial cell enclosing numerous mitotic immature thymocytes. These observations and the previously reported mitogenic and immunomodulatory properties of VP and OT upon mature T cells and thymocytes strongly support the existence of a neuroendocrine thymo-lymphoid axis and an active role of thymic VP and OT in T cell differentiation and activation.

Humans↗
PubMed1989

Angiogenic activity of the atherosclerotic carotid artery plaque.

Neovascularization is observed in complicated atherosclerotic plaques associated with cellular proliferation, plaque hemorrhage, and thrombosis. The angiogenic activity of 278 plaque fragments was tested; the fragments were taken from 12 patients with cerebral ischemia who underwent carotid endarterectomy. Angiogenesis, determined by the sustained ingrowth of new vessels in the rabbit cornea, was induced in 125 (45%) of these fragments. By contrast, angiogenesis was found in only two (2.4%) of 80 control tissues (p less than 0.001): in none of 22 samples of boiled atherosclerotic plaque; in two of 26 samples of normal rabbit carotid artery; and in none of 32 samples of nonatherosclerotic human uterine artery. Histological evaluation revealed that the cellular zones (composed mainly of smooth-muscle cells) were highly angiogenic, with 97 (76%) of 127 samples showing angiogenesis compared with 23 (17%) of 132 acellular fragments that consisted of amorphic, necrotic, calcific, lipid-laden material (p less than 0.001). These results indicate that angiogenesis in vivo is a function of the cellular component of the advanced atherosclerotic plaque, and is not expressed in the normal, stable arterial wall. The fragile new vessels could promote the growth of the plaque or be a source of hemorrhages, microinfarcts, and plaque fissures that convert a stable, silent lesion to an expanding, ulcerated, thrombotic, symptomatic plaque.

Aged↗
PubMed1988

The neuroendocrine thymus. Abundant occurrence of oxytocin-, vasopressin-, and neurophysin-like peptides in epithelial cells.

Certain subtypes of thymic epithelial cells--the medullary epithelium, the cortical surface epithelium, and some intracortical epithelial cells--show strong immunohistochemical reactivity with antisera against oxytocin, Arg-vasopressin and neurophysin. The epithelial nature of the neuropeptide containing cells is shown by their morphology and their reactivity with monoclonal anti-cytokeratin AE1/E3. Hassall's corpuscles are positive as well. The immunoreactivity patterns for the three neuropeptides are identical, suggesting a parallel distribution. The vast majority of cortical epithelial cells are negative, emphasizing the tightly controlled microenvironment for T-cell development. The possibility of a neuroendocrine role of the thymus is discussed.

Adolescent↗