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Biomedical subjects

M Vandeputte

Publications and source records attributed to M Vandeputte.

At least 91 records · Page 5Linked to original sources
PubMed1989

Nature of the multipotential cells in the displaced rat yolk sac.

The nature and origin of the proliferating cells were studied in displaced visceral yolk sac in vivo and in organ culture in vitro. By ultrastructural examination and reactivity with antibodies against intermediate filaments it was shown that the poorly differentiated cells which appear in this membrane have features in common with visceral endodermal cells. Using plant lectins reacting with the rat visceral endoderm (DBA, PNA, SJA and BSA-1) it was demonstrated that the proliferating endodermal cells retrodifferentiate to earlier stages of endodermal development.

Animals↗
PubMed1989

Maternal and fetal endocrine pancreas in the spontaneously diabetic BB rat.

The maternal and fetal endocrine pancreas were investigated in the diabetic BB rat on day 21 of pregnancy. The maternal pancreas of the diabetic rat contained practically no insulin-positive B cells. The A and D cell mass were also decreased, while plasma glucagon and somatostatin levels were normal or increased, confirming previous data. Six of 11 diabetic rats had B-cell-specific surface antibodies (ICSA), whereas only 1 of 10 nondiabetic rats was ICSA-positive. The volume density of insulin-positive cells was decreased in the fetal pancreas of diabetic BB rats compared to fetuses of nondiabetic rats, but the volume density of glucagon- and somatostatin-positive cells remained normal. The B cells of these fetuses were ultrastructurally less granulated and showed signs of increased cellular activity. Plasma insulin levels were decreased while plasma glucagon and somatostatin concentrations were normal. ICSA were not detected in fetuses of nondiabetic and diabetic rats. There were no differences in the histology of the spleen and thymus between both groups of fetuses. Metabolic characterization of the growth-retarded fetuses of diabetic rats revealed, besides lower plasma insulin concentrations, increased branched chain amino acid levels, and normal plasma Sm/IGF-I levels. The main conclusions from this study are: (1) Severe maternal diabetes decreases the pancreatic insulin-positive cell mass and plasma insulin levels in the fetus, but not the A and D cell mass and function; (2) ICSA are not detectable in fetal plasma; (3) the influence of maternal BB rat diabetes on fetal endocrine pancreas and metabolic environment resembles that of severe streptozotocin-induced diabetes.

Animals↗
PubMed1988

In vivo localization and biological effect of anti-yolk sac monoclonal antibodies.

Two monoclonal antibodies directed against rat yolk sac antigen 1 (mab 6D1) and yolk sac antigen 2 (mab 3C3) were injected i.v. into pregnant or tumor-bearing rats. Immunofluorescent examination of the different organs from animals killed, 2, 24, or 48 hours after inoculation showed the specific binding of mab 6D1 to the free surface of visceral endoderm cells in pregnant animals and on visceral cells of yolk sac carcinoma. The mab 3C3 reacted only with the endoderm of parietal yolk sac and with a distinctive parietal pattern of the tumor. The reaction was strong after 2 and 24 hours following injection and much weaker after 48 hours. The 3C3 mab had an embryotoxic effect, whereas the 6D1 mab did not influence the development of the fetus.

Animals↗
PubMed1988

Renal cadaveric transplantation in diabetics using total lymphoid irradiation or cyclosporin A. A controlled randomized study. Leuven Collaborative Transplantation Group.

A total of 20 renal transplant patients with end-stage diabetic nephropathy entered a randomized controlled trial comparing preoperative, fractionated total lymphoid irradiation (TLI) (radiation dose, 20-30 Gy) with postoperative cyclosporin A (CsA). Both groups received postoperative low-dose methylprednisolone maintenance therapy. The 3-year patient and graft survival was similar for both groups (100% and 71% in the TLI and 75% and 75% in the CsA group, respectively). Rejection crises occurred significantly more frequently (P less than 0.01) in the TLI-treated recipients. The incidence of infectious or diabetic complications was not significantly different in both groups. It is concluded that TLI and CsA are both effective treatment modalities for cadaveric renal transplantation in diabetics; CsA, however, is superior in preventing rejection crises.

Adult↗
PubMed1988

Experimental rat model for human yolk sac tumor.

The morphological and biological characteristics of experimentally induced rat yolk sac carcinomas (ysca) are compared to those of human yolk sac tumors. It is shown that the rat ysca shares many morphological and biological properties with its human counterpart although the cellular origin is probably different. Whereas the human yolk sac tumors are believed to be of germ cell origin, the rat visceral yolk sac-derived tumors are not. The hypothesis is formulated that the rat ysca are derived from multipotential cells different from germ cells, and which originate in the extra-embryonic membrane after displacement.

Animals↗
PubMed1988

Treatment of murine lupus nephritis with cyclophosphamide or total lymphoid irradiation.

Untreated 9 to 11 month-old, female NZB/W F1 mice all died within six weeks (wks) after the occurrence of nephrotic range proteinuria (greater than or equal to 3 g/liter). Significant prolonged survival could be obtained in similar groups of animals either by weekly i.v. pulses of cyclophosphamide (CY, 25 mg/kg, 40% survival 20 wks after start of treatment) or by administering total lymphoid irradiation (TLI, 17 daily fractions of 2 Gy, 70% survival at 20 wks). All surviving animals in both groups showed remission of the nephrotic range proteinuria. In all treated mice, light microscopy examination of the kidneys revealed a decrease of inflammation and a stabilization of proliferation and sclerosis, yet immunofluorescence for IgM, IgG and C3 was not significantly altered. The better survival of the TLI- as compared to the CY-treated mice (P less than 0.001) was due to a lower incidence of lymphomas or viral infections. IgG anti-DNA auto-antibodies were significantly lowered by CY but not by TLI treatment. It is concluded that CY pulse therapy and TLI are both efficient treatment modalities for high grade lupus like NZB/W disease. In this model TLI is safer than CY when used in a dose regimen of 25 mg/kg/wk and interferes with the course of the disease without lowering the IgG anti-DNA antibodies.

Animals↗
PubMed1988

Immunohistochemical localization of yolk sac antigen 1 on rat spermatogenic cells.

The reactivity of monoclonal antibody (6D1, mAb) directed against yolk sac antigen 1 was verified on testes of young and adult rats. The antigen defined by 6D1 mAb was detected on the earliest appearing pachytene spermatocytes in the testis of 18-day-old rats. In the testis of the adult rat, the mAb reacted with pachytene spermatocytes, spermatids and spermatozoa. Less differentiated cells of spermatogenesis, for example spermatogonia and early spermatocytes, showed no reaction with the 6D1. Only after breaking down the blood-testis barrier, could the mAb injected intravenously reach the spermatogenic cells of the adluminar compartment in the seminiferous tubules.

Animals↗
PubMed1988

Shortage of kidneys, a solvable problem? The Leuven experience. Leuven Collaborative Group for Transplantation.

Our 10-year experience with the LCGT indicates that close collaboration of nephrologists from peripheral centers for the long-term follow-up of transplanted patients presented no obstacles to excellent patient and graft survival rates. At the same time, "decentralization" greatly increased the motivation of collaborating centers to participate in organ procurement. In addition, the introduction of an "opting out" law provided spectacular stimulation for collaborating center participation. For the first time in many years, the number of transplants was higher than the number of new candidates registered on the waiting list.

Actuarial Analysis↗
PubMed1987

Structure and expression of mos sequences in spontaneous and Moloney murine sarcoma virus-induced yolk sac carcinomas in rats.

Facilitation of yolk-sac carcinoma (YSCa) development in fetectomized rats by the Moloney murine sarcoma virus/murine leukemia virus (Mo-MSV/MLV) complex was found to be closely associated with the presence of Mo-MSV sequences in the genomes of the YSCa cells. The virus-induced YSCas consisted of cells of mono- or oligoclonal origin which always contained in their genomes at least I randomly integrated Mo-MSV provirus. In YSCas which developed in the absence of virus, no rearrangement or amplification of c-mos could be detected. In addition, blot hybridization analysis of cellular RNA failed to detect mos-related RNA in cell lines derived from Mo-MSV-induced as well as from non-virally induced YSCas. The methylation level of c-mos DNA was low in all YSCa cell lines. In contrast, v-mos DNA in cell lines derived from Mo-MSV-induced YSCas was heavily methylated.

Animals↗
PubMed1987

Both 2',3'-dideoxythymidine and its 2',3'-unsaturated derivative (2',3'-dideoxythymidinene) are potent and selective inhibitors of human immunodeficiency virus replication in vitro.

2',3'-Dideoxythymidine (ddThd) and its 2',3'-unsaturated derivative 2',3'-dideoxythymidinene (ddeThd) are potent and selective inhibitors of human immunodeficiency virus (HIV) in vitro. When evaluated for their inhibitory effects on the cytopathogenicity of HIV in MT-4 cells, ddThd and ddeThd completely protected the cells against destruction by the virus at a concentration of 1 microM and 0.04 microM, respectively. In this aspect, ddeThd was about 5 times more potent than 2',3'-dideoxycytidine (ddCyd), one of the most potent and selective anti-HIV compounds now pursued for its therapeutic potential in the treatment of AIDS. ddThd and ddeThd also suppressed HIV antigen expression at 1 microM and 0.04 microM, respectively. Their selectivity indexes, as based on the ratio of the 50% cytotoxic dose to the 50% antiviral effective dose, were 120 (ddeThd) and greater than 625 (ddThd).

Antigens, Viral↗
PubMed1987

Sensitive and rapid assay on MT-4 cells for detection of antiviral compounds against the AIDS virus.

Human immunodeficiency virus (HIV) infection of MT-4 cells, an HTLV-I-transformed T-cell line, proved to be a rapid and sensitive assay system for the detection of potential antiviral drugs effective against the acquired immune deficiency syndrome (AIDS). Four days after HIV inoculation of the MT-4 cells, viral antigen expression was monitored in parallel with indirect immunofluorescence microscopy and laser flow cytofluorography. When 3'-azido-2',3'-dideoxythymidine (AzddThd, AZT) and 2',3'-dideoxycytidine (ddCyd) were evaluated under these conditions, they inhibited viral antigen expression at a minimum (33% inhibitory) concentration of 0.0004 and 0.02 microM, respectively. Similar minimum effective concentrations were found for AzddThd and ddCyd in assays where inhibition of viral cytopathogenicity was based on cell survival. While laser flow cytofluorography could be best adapted for quantitative measurements, cell survival and reconstitution of disrupted cell aggregates gave an equally rapid and sensitive endpoint; and the latter may be ideally suited for preliminary drug screening.

Antigens, Viral↗
PubMed1987

Neoplastic transformation of the rat visceral yolk sac by polyoma virus.

The transforming activity of polyoma virus was verified in vitro in organ cultures of 12-day old rat visceral yolk sacs and embryos. Organ cultures of 18-day old fetal organs were also included. The transforming capacity of the virus was found to be restricted to the endothelial cells of the rat visceral yolk sac. The neoplastic endothelial cells are readily transplantable and possess the polyoma tumor-specific transplantation antigens (TSTA).

Animals↗
PubMed1987

Immunological and clinical observations in diabetic kidney graft recipients pretreated with total-lymphoid irradiation.

In a feasibility study, twenty patients with end-stage diabetic nephropathy were treated with fractionated total-lymphoid irradiation (TLI, mean dose 25 Gy), before transplantation of a first cadaveric kidney. During radiotherapy, only one patient had a serious side effect (bone marrow depression). After transplantation four patients died (one of a myocardial infarction, one of ketoacidosis, and two of infections occurring during treatment of rejection crises). One graft was lost because of chronic rejection. The other 15 patients have a functioning graft (mean follow-up 24 months) and receive low-dose prednisone alone (less than 10 mg/day, n = 11) or in conjunction with cyclosporine (n = 4) as maintenance immunosuppressive therapy. A favorable clinical outcome after TLI (no, or only one, steroid-sensitive rejection crisis) was significantly correlated with a high pre-TLI helper/suppressor lymphocyte ratio, a short interval between TLI and the time of transplantation, and the occurrence of functional suppressor cells early after TLI. The most striking immunological changes provoked by TLI consisted of a long-term depression of the mixed lymphocyte reaction and of the phytohemagglutinin, and Concanavalin A or pokeweed-mitogen-induced blastogenesis. A rapid and complete recovery of the natural killer cell activity was observed after TLI. A permanent inversion of the OKT4+ (T helper/inducer) over OKT8+ (T suppressor/cytotoxic) lymphocyte ratio was provoked by a decrease of the OTK4+ subpopulation, together with a supranormal recovery of the OKT8+ lymphocytes. A majority of the latter lymphocytes did also express the Leu 7 and the Leu 15 phenotype.

Adult↗
PubMed1986

Identification of a major Leu 7/OKT 8 positive T-lymphocyte subpopulation in renal transplant patients pre-treated with total lymphoid irradiation.

When pretreated with total lymphoid irradiation, renal allograft recipients have an increased percentage of OKT 8 positive (cytotoxic/suppressor) T cells among their peripheral blood T lymphocytes (PBL) (56 +/- 21%) and also of Leu 7 PBL (47 +/- 18%). In contrast, transplant patients treated with azathioprine or cyclosporine A have percentages of OKT 8 and Leu 7 positive PBL, similar to control persons (respectively 29 +/- 13, 33 +/- 10, 30 +/- 10 for the OKT 8+ cells and 8 +/- 7, 11 +/- 6 and 15 +/- 9 for the Leu 7+ cells). After purification, about two thirds (70%) of the OKT 8 positive, OKT 3 positive, T lymphocytes of TLI patients were shown to co-express the Leu 7 antigen. It is concluded that after TLI, an increase of OKT 3+, OKT 8+ and Leu 7+ lymphocytes takes place, a subset previously described to be present in low numbers in control persons and whose function is still unclear. This expansion after TLI should allow functional identification of this subset and might contribute to the understanding of the immunosuppressive effects of TLI.

Antibodies, Monoclonal↗