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Biomedical subjects

J Jansen

Publications and source records attributed to J Jansen.

At least 163 records · Page 9Linked to original sources
PubMed1989

Characterization of specific insulin-like growth factor (IGF)-I and IGF-II receptors on cultured rabbit articular chondrocyte membranes.

The interaction of insulin-like growth factor (IGF)-I and IGF-II with specific type-I and -II receptor sites on rabbit articular chondrocyte membranes was studied. With labelled IGF-I as tracer, half-maximal displacement of the label was obtained with 1.4 ng IGF-I/ml and 22 ng IGF-II/ml. Using IGF-II as labelled peptide. 16 ng unlabelled IGF-II/ml and 200 ng IGF-I/ml were needed to inhibit the binding by 50%. Covalent cross-linking experiments revealed the presence of typical type-I (Mr 130,000 under reducing conditions) and type-II (Mr 260,000) receptor sites. In addition, with 125I-labelled IGF-II a very intense labelled band appeared at Mr greater than 300,000. This band was not found in mouse liver membranes and human placental membranes.

Animals↗
PubMed1989

A concise history of the Ostertagiinae Lopez-Neyra, 1947 (Nematoda: Trichostrongyloidea) and a discussion on its composition.

After a historical introduction to the Ostertagiinae and several revisions of this group, it is proposed that the subfamily shall contain seven genera: Ostertagia, Hyostrongylus, Longistrongylus, Marshallagia, Mazamastrongylus, Spiculopteragia and Teladorsagia. The synonyms of these genera are to be found in the literature. In this proposal the genus Hyostrongylus should belong to the Ostertagiinae though it has probably an intermediate position between the Ostertagiinae and Graphidiinae. Cervicaprastrongylus and Tunisostertagia are regarded as synonyms of Hyostrongylus and Ostertagia respectively. The position of Ostertamia and Trichostrongyella is not clear but they could have their closest affinities with Teladorsagia and Mazamastrongylus respectively. The origin of the subfamily and the relationships of the genera with regard to their preferences for host groups and to their geographical distribution are discussed.

Animals↗
PubMed1989

Use of carboplatin in the treatment of testicular cancer.

Recent evidence indicates that carboplatin may be useful in the treatment of various forms of testicular cancer. The results of one study showed that carboplatin was highly effective and well tolerated in patients with previously untreated disseminated seminoma. However, conventional doses of carboplatin appear to be inactive in patients with refractory nonseminoma. Of particular interest are recent results showing that an intensive regimen of carboplatin in combination with etoposide with autologous bone marrow rescue will induce a few complete remissions in heavily pretreated germ cell tumor patients.

Antineoplastic Agents↗
PubMed1988

Enhancement of release of granulocyte- and granulocyte-macrophage colony-stimulating factors from phytohemagglutinin-stimulated sorted subsets of human T lymphocytes by recombinant human tumor necrosis factor-alpha. Synergism with recombinant human IFN-gamma.

The influence of purified recombinant human TNF-alpha (rhuTNF-alpha) was assessed, alone and in combination with purified recombinant human IFN-gamma (rhuIFN-gamma), for its effects on enhancing release from human T lymphocytes of activities that stimulate colony formation by granulocyte-macrophage, erythroid, and multipotential progenitor cells. rhuTNF-alpha or rhuIFN-gamma enhanced the release of CSF, which were determined to be granulocyte-CSF and granulocyte-macrophage-CSF by human bone marrow colony assays, morphologic assessment of colony types, and neutralization studies with rabbit anti-human granulocyte-CSF and monoclonal mouse anti-human granulocyte-macrophage-CSF. The CSF were released only when PHA was used, whether or not rhuTNF-alpha and/or rhuIFN-gamma were present while the lymphocytes conditioned the medium. T lymphocytes were sorted into subsets by using three-color immunofluorescence and a dye laser flow cytometry system with cells incubated with biotin anti-Leu-4 labeled with Texas Red, FITC-conjugated anti-Leu-3a, and phycoerythrin-conjugated anti-Leu-2a. Both the Leu-4+3a+2a- and the Leu-4+2a+3a- cells released CSF in response to PHA, but the release of CSF from PHA-stimulated lymphocytes was enhanced by rhuTNF-alpha and rhuIFN-gamma only from the Leu-4+3a+2a- subset of cells. Use of the three-color cell sorting made it highly unlikely that NK cells were involved, because both sorted subsets were positive for Leu-4. rhuTNF-alpha and rhuIFN-gamma synergized to enhance release of CSF such that low concentrations of each molecule, which were inactive when used alone, were active when the two molecules were used together. These studies suggest a role, at least in vitro, for TNF-alpha and IFN-gamma in the release of CSF from subsets of T lymphocytes stimulated with PHA.

Adjuvants, Immunologic↗
PubMed1988

Influence of T lymphocytes on hematopoiesis in a patient with T cell hypoplasia.

In this communication, we describe an unusual patient with a reported lifelong history of anemia. Investigation of the pathogenesis of this patient's bone marrow failure provided an interesting opportunity to determine the role of T cells in the regulation of human blood cell production. Phenotyping of the patient's mononuclear cells revealed severe T cell hypoplasia in both the peripheral blood and bone marrow. The patient's bone marrow was capable of producing 50-60% of the normal numbers of burst-forming units--erythroid (BFU-E) in the presence of optimal concentrations of erythropoietin, suggesting that marrow BFU-E formation is in part independent of T cells. Addition of small numbers of class I identical donor T cells enhanced BFU-E cloning efficiency to a level observed in normal controls. This enhancing effect was supplied by a T4+ (CD4) population of donor cells. The addition of donor T cells partially corrected the inability of patient marrow cells to produce megakaryocyte and mixed colonies. These studies suggest that prolonged T cell hypoplasia might deprive marrow progenitor and stem cells of a necessary enhancing effect that is required for sustained normal hematopoiesis. Such a T cell defect in rare instances may result in bone marrow failure.

Aged↗
PubMed1988

Etiology and prognosis in hydrocephalus.

In a retrospective study, 219 hydrocephalic patients from the preshunt era were identified. Mortality and working ability in survivors 21-35 years old were examined in different etiological groups. In one-third, no etiological factor was known or suspected. Of the remaining patients, 30% had more than one possible etiological factor. Patients with verified infection or trauma had a higher mortality than patients with suspected infection or trauma. However, survivors with suspected trauma and infection did not fare any better than survivors with verified trauma or infection. An etiology of hydrocephalus offers little help when evaluating prognosis in an individual patient. The reasons for this may be that the classifications are ambiguous, the groups too heterogenous, or that the "etiology of hydrocephalus" is not relevant, since it is sign and not a disease entity.

Cerebrospinal Fluid Shunts↗
PubMed1988

Cytogenetic patterns following bone marrow transplantation for chronic granulocytic leukemia.

Allogeneic bone marrow transplantation (BMT) is the only treatment with a potential to cure chronic granulocytic leukemia (CGL). Cytogenetic markers, including the Philadelphia chromosome (Ph), t(9;22)(q34;q11), allow follow-up of these patients after BMT for engraftment and remission status. A variety of cytogenetic patterns have been observed after BMT for CGL. A number of patients experience cytogenetic relapse or mixed chimerism with normal cytogenetics. Furthermore, these types of complications may increase after T-cell depleted BMT. We have closely followed six patients with Ph-positive CGL treated with T-cell depleted bone marrow for 169-720 days after BMT. A number of different cytogenetic patterns were found. The first patient, transplanted while in accelerated phase, relapsed at 155 days with the same clonal abnormalities and died in blast crisis. Four other patients were found to have cytogenetic relapses between days +41 and +233. In every case the Ph reappeared along with other clonal and nonclonal abnormalities, some of which were transient. All four patients presented with hematologic relapse several months after cytogenetic relapse. The final patient has mixed chimerism with Ph-negative cells and continues to be in clinical remission. Close cytogenetic follow-up of CGL patients after BMT can provide important information about early changes in engraftment and remission status.

Adult↗
PubMed1988

Functional and phenotypical studies of the Leu-4 (CD3)+, Leu-1 (CD5)- T lymphocyte.

A small T cell subpopulation expressing the phenotype Leu-5(CD2)+, Leu-4(CD3)+, Leu-1 (CD5)- can be found in peripheral blood and bone marrow of normal individuals. When these cells were sorted out by three colour immunofluorescence cell sorting and tested in limiting dilution assays, they were found to have lower frequencies of proliferating (9.0 +/- 5.6 times, n = 7) and of IL-2 producing cells (11.5 +/- 5.0 times n = 5), and a higher frequency of cytotoxic cells (3.1 +/- 2.6 times, n = 2) than T lymphocytes expressing the three markers. In peripheral blood lymphocytes, 1/3 of the CD3+, CD5- cells were positive for Leu-2a (CD8) while virtually all were negative for Leu-3a (CD4). Four colour flow cytometric analysis revealed a small subset of T cells positive for CD3 and negative for CD5, CD4 and CD8. Approximately 75% of the CD3+, CD5- cells were negative for Leu-7 and CD16 simultaneously. These results shed a light on the phenotype of T cells that escape killing by CD5 and complement in T cell depleted bone marrow and may explain why fewer residual T cells in the depleted marrow are detected by limiting dilution assays than by flow cytometric analysis.

Antigens, Differentiation↗
PubMed1988

Development of smaller artificial ventricles and valves made by vacuum forming.

Implantable prosthetic ventricles and trileaflet valves made by vacuum forming have been developed and implant tested. All components are made from Pellethane. Recognizing the need for smaller as well as larger ventricles, designs with effective stroke volumes of 50, 85, 100 and 130 cc have been tested with several valve types. The pneumatically driven Utah ventricular assist device (UVAD) can be used as a total artificial heart (TAH) or ventricular assist device (VAD) by using the appropriate inflow and outflow adapters. In vitro durability testing has demonstrated ventricular lifetime beyond two years and valve lifetime to nearly one and one half years. The polymer valves have lower regurgitation than mechanical valves. Animal implantation experience includes 21 TAH implants and 16 left ventricular assist device (LVAD) implantations. TAH survival ranges from 2 to 210 days. LVAD animals have lived up to 116 days before elective termination. The animal were healthy and grew normally. The devices exhibit a "Starling's Law" response. One TAH animal survived 72 days before successful explantation followed by transplantation. At autopsy, this animal had no renal infarcts. Hematology data has demonstrated the existance of little or no intravascular hemolysis (PF Hb less than 5 mg%). The "Philadelphia" version of the UVAD vacuum formed ventricles are small enough to be implanted without thrombus provoking connectors. Eight animals have received this TAH and survived up to 120 days. Vacuum forming offers a rapid and inexpensive way to produce reliable and effective total artificial hearts and valves for widespread, temporary clinical application in any size adult human.

Animals↗
PubMed1987

[Fertility in relation to production in dairy cattle].

A review of the relationship between fertility of production in dairy cattle is presented. At farm level almost no relationship was found, except that farms in the lowest production class had lower fertility rates. Within farms there was a weak antagonistic relationship. Better dairy cows were first presented slightly later and needed more inseminations to achieve pregnancy. The genetic capacities for production and fertility appear, especially in the first lactation, to be negatively related. In older animals, the relationship was absent or even slightly positive. Animals with a lower productive capacity are generally culled earlier for fertility problems than high-producing animals. Thus a negative relationship between production and fertility can always be established. In selection experiments on milk production, no adverse effects on the fertility of young animals were observed. The effects at older ages were negative, but small.

Age Factors↗
PubMed1987

The intraneoplastic chemotherapy in a rat brain tumour model utilizing methotrexate-polymethylmethacrylate-pellets.

In an experimental glioma model, using ethylnitrosourea induced and subsequently intracerebrally implanted tumours in BD-IX rats, the effectiveness of intratumoural application of methotrexate (MTX) by stereotactic implantation of polymethylmethacrylate (PMMA) pellets containing MTX, has been studied. Tumour volume 10 days after pellet implantation as well as survival rates of treated, untreated and control animals have been the criteria of the effect of treatment. Tumour volume was significantly smaller in treated compared to untreated animals. The survival rate of untreated to treated animals increased 150 and 233% respectively when compared with the control animals. Thus a positive therapeutic effect of MTX-PMMA pellet implantation in the experimental glioma could be proven. Possible consequences for the treatment of human gliomas are shortly discussed.

Animals↗
PubMed1987

Chronic T cell lymphoproliferative disorder and pure red cell aplasia. Further characterization of cell-mediated inhibition of erythropoiesis and clinical response to cytotoxic chemotherapy.

Two patients with pure red cell aplasia and a T cell lymphoproliferative disorder were studied in order to define the mechanism of suppression of erythropoiesis and the patients' response to cytotoxic therapy. In vitro assays demonstrated enhanced formation of both erythroid colonies and bursts following T-cell depletion. Erythroid colony formation was suppressed by the readdition of autologous T cells to a null cell fraction of marrow mononuclear cells. Media conditioned by the patients' T cells did not exhibit any inhibitory effect on erythroid colony formation by autologous T cell-depleted marrow cells. These in vitro results suggested that T cell-mediated suppression of erythropoiesis was responsible for the generation of pure red cell aplasia. In both patients, cyclophosphamide therapy resulted in clinical remissions manifested by normalization of the hematocrits associated with a reduction in circulating lymphocytes from more than 10,000/mm3 to under 500/mm3. Maintenance chemotherapy has caused persistent inhibition of lymphocyte counts along with durable remissions with normal hematocrits.

Aged↗