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Biomedical subjects

J Knop

Publications and source records attributed to J Knop.

At least 181 records · Page 10Linked to original sources
PubMed1985

[Bone scintigraphy in assessing the success of chemotherapy in osteosarcoma].

During preoperative chemotherapy regional 99mTc-MDP clearance by tumor and healthy bone as well as tumor blood flow were determined in 13 patients with osteosarcoma. The results were compared to histologic regression grades. After good response (tumor vitality less than 10%) tumor blood flow normalized and regional 99mTc-MDP clearance decreased by 66% (range 56-82%). After poor response to chemotherapy (tumor vitality greater than 10%) tumor blood flow remained increased, whereas regional 99mTc-MDP clearance was unchanged or increased except in one patient. After 4-7 weeks of chemotherapy tumor viability was accurately assessed in 8 of 9 patients (89%) by means of regional 99mTc-MDP clearance. Tumor viability could be evaluated also by simple tumor/non-tumor ratios. A decrease of 99mTc-MDP clearance by more than 20% indicated an effective chemotherapy with a specificity of 80%. After 10-13 weeks of chemotherapy the specificity was improved including the results of tumor blood flow determination.

Adolescent↗
PubMed1985

[Immunologic basis of allergic contact eczema].

Allergic contact dermatitis is an inflammatory skin disorder induced by low molecular and reactive haptens (contact allergens) coming into contact with the skin of sensitized individuals. The sensitization or induction phase is characterized by an activation of allergen-specific T-effector lymphocytes. For proliferation and differentiation of these cells presentation of hapten, associated with Ia-molecules on the surface of Langerhans cells, is required. Further activating and modulating signals are delivered by interleukin 1, interleukin 2, interferon, prostaglandins and some more. The activation and function of the T-effector cells is controlled by T-suppressor lymphocytes. Antibody, in particular antiidiotype antibody, can be regulators of this cell-mediated immune response. The effector phase is characterized by a reaction of the T-effector lymphocytes with the eliciting allergen: this results in a secretion of lymphokines. Lymphokines attract and activate other cells such as macrophages, lymphocytes, neutrophile and basophile leukocytes. These cells release inflammatory mediators.

Antigen-Presenting Cells↗
PubMed1985

Inhibition of the anti-receptor antibody response of contact sensitivity by interferon.

Mice sensitized with optimal doses of 2,4-dinitrofluorobenzene (DNFB) develop maximum delayed hypersensitivity in 4-5 days; the intensity of this reaction declines rapidly 14 days after sensitization. In the serum of mice 14 days after sensitization, an anti-receptor antibody has been described. It has been suggested that this antibody might be responsible for this rapid decline of contact sensitivity. We studied the effect of interferon alpha, beta (IFN alpha, beta) and cyclophosphamide (Cy) in this model. IFN alpha, beta (2 X 10(4) units/ mouse) or Cy (200 mg/kg) injected at Days 0 and 1 during sensitization, or at Day -2 before sensitization, respectively, partially prevented the decline of contact sensitivity as compared to the controls. In the serum of mice treated with IFN or Cy, no anti-receptor antibody could be detected 14 days after sensitization. These results suggest that anti-receptor antibody may be partially responsible for the waning of contact sensitivity. It is further suggested that IFN inhibited the anti-receptor antibody response by preventing the generation of the anti-receptor-antibody-inducing auxiliar T-suppressor cell. It is concluded that IFN alpha, beta enhances the delayed hypersensitivity response in contact allergy by inhibition of the T-suppressor circuit, as previously reported, and by suppression of the anti-receptor antibody response.

Animals↗
PubMed1985

Late mortality following Billroth II resection for duodenal ulcer.

In a follow-up study of 1 000 patients subjected to Billroth II resection for duodenal ulcer in the period 1948-1956, the late mortality up to the end of 1977 (522 patients) was analyzed. The observed mortality was compared with the expected mortality calculated by the life-table method and indirectly standardized for age, sex, domicile and time and cause of death. The overall mortality rate was significantly increased, mainly due to suicide, which occurred at five times the expected rate and could be related to excessive alcohol consumption and psychiatric disturbances. Malignant neoplasms, including gastric carcinoma, were not more common than expected as causes of death. The same applied to pulmonary tuberculosis, other respiratory disorders, cardiovascular, gastro-intestinal and urogenital disease and to accidents. It is concluded that the main mortality risk factors were psychiatric disease and alcohol consumption.

Adolescent↗
PubMed1985

[Function scintigraphy: a uniform method for quantifying organ metabolism and function].

Functional scintigraphy is a quantitative method with which metabolic parameters of an organ can be determined by measuring the time activity course of a radioactive tracer in tissue. Their quantitative value is, however, limited by inherent sources of error, e.g. the absorption of radiation in the organ or overlapping of fore- and background activities. Hitherto, existing procedures for calculation of metabolic parameters are based more on given technical possibilities than on common theoretical foundations. They are notable for their variety in methodical approach, frequently being of empirical character. Quantitative results from different institutes and hospitals can therefore rarely be compared. The present work describes a methodical approach to obtain comparable methods in nuclear medicine, by including the pharmacokinetics of a tracer in blood. This leads to the compartment analysis (deterministic) or to a stochastic (non-deterministic) description of the kinetics in an organ. The stochastic description requires the calculation of the linear response function from a convolution integral. By means of functional analytical methods a mathematical procedure has been developed which for the first time permits the calculation of the linear response function in each pixel and at any time of the study. Easily readable functional images show how relevant parameters can be calculated from the linear response function. Due to its independence on any model, the linear response function enables furthermore a regional investigation of existing or new compartment models of tracer kinetics in the organ concerned.

Bone and Bones↗
PubMed1985

[New criteria for scintigraphic follow-up of bone metastases following radiotherapy. Results of functional scintigraphy using 99mTc-MDP].

After radiation therapy regional 99mTc-MDP clearance by 17 metastatic lesions was determined repeatedly in 13 patients. 99mTc-MDP clearance rates decreased within 14 weeks after irradiation of osteoblastic metastases, but were normalized in only one lesion. In osteolytic lesions 99mTc-MDP clearance increased 4 weeks after completion of radiation therapy indicating reossifications evident from X-ray examinations subsequently. 99mTc-MDP clearance decreased subsequently and returned to normal after 28-50 weeks in 6 out of 11 metastases demonstrating reossification on X-ray. Monitoring of radiation therapy of bone metastases should be adapted to these complex variations of tracer kinetics. The initial increase of tracer accumulation in osteolytic metastases due to bone repair should not be misinterpreted as a local progression of metastatic bone disease.

Adult↗
PubMed1984

Selective induction of delayed hypersensitivity T-effector and T-suppressor lymphocytes in vitro by haptenized bone marrow-derived macrophages.

The role of various subpopulations of antigen-presenting macrophages in the induction of T-lymphocyte subpopulations has been difficult to study in the past. We have used an in vitro system of bone marrow cell culture both to induce T-effector (TDH) and T-suppressor (Ts) cells active in delayed-type hypersensitivity. Bone marrow-derived macrophages (BM-MA) grown in Teflon bag cultures were allowed to attach to culture dishes and were pulse-labeled with 2,4-dinitrobenzene sulfonate (DNBSO3). Spleen cell lymphocytes from nonsensitized BALB/c mice were cocultured with antigen-pulsed or control BM-MA for 3 days. The lymphocytes were harvested, and injected iv into BALB/c mice which were challenged within 1 hr after injection by painting the right ear with 2,4-dinitrofluorobenzene (DNFB, effector test) or sensitized with DNFB on 2 days following iv injection of the cells and challenged 5 days later (suppressor test). Ear swelling was measured 24 hr later to assess the effector or suppressor function of the in vitro educated lymphocytes. BM-MA grown for 5 days (BM-MA 5) in L-cell conditioned medium induced only TDH cells (Thy 1+, Lyt 1+2-) whereas BM-MA grown for 10 days in conditioned medium induced only Ts cells (Thy 1+, Lyt 1-2+). In both cases, induced TDH and Ts cells were antigen specific. Functionally, induced Ts cells suppressed the afferent limb of the delayed response. When DNP-BM-MA 5 and DNP-BM-MA 10 were used to induce TDH or Ts cells in vivo by subcutaneous or intravenous injection respectively, only BM-MA 5 were able to sensitize recipient mice. Both 5- and 10-day macrophage populations induced Ts cells in vivo. Functionally, these Ts cells appeared to act on the efferent limb of the delayed reaction. We conclude that different populations of antigen-presenting macrophages can preferentially induce TDH or Ts cells, perhaps depending on antigen presentation in association with class II antigens or on the functional state of the antigen-presenting cell.

Animals↗
PubMed1984

[Behçet disease with inner ear involvement].

Behçet's disease may also insolve the inner ear. We report on a 24-year-old man having suffered from defective hearing already since two years after onset of Behçet's disease. During the follow-up period, vertiginous attacks, tinnitus, as well as feeling of pressure in both ears have been additionally observed.

Adult↗
PubMed1984

Evidence for an endothelial cell dysfunction in association with Behçet's disease.

Suppression of the fibrinolytic system is a well-known phenomenon in patients with Behcet's disease regardless of whether they present thrombotic complications. This finding has been related to impaired production and/or release of plasminogen activators from the vascular endothelium. In previous studies a diminished release of PF4 upon heparin stimuli was observed in plasma from patients with Behcet's disease and interpreted as an additional indicator for endothelial cell dysfunction. In the present investigations, 12 patients and 10 healthy volunteers received DDAVP infusions and euglobulin clot lysis time, factor VIII activities and 6-keto-PGF1 alpha levels in plasma were repeatedly determined before and after infusions. At different times following DDAVP infusion, euglobulin clot lysis time was significantly longer and levels of F.VIII R:Ag were lower in patients than in normals. F. VIII:C activity increased in both groups, whereas no changes were seen in the plasma levels of 6-Keto-PGF1 alpha either in normals or in patients. It is concluded that the disseminated damage of endothelial tissue associated with Behçet's disease correlates with multiple endothelial cell dysfunctions and subsequent hemostatic abnormalities.

6-Ketoprostaglandin F1 alpha↗
PubMed1984

Selection of the delayed hypersensitivity T effector and T suppressor cell response by antigen-presenting macrophages.

The T effector lymphocytes of delayed type hypersensitivity reactions (TDH) are regulated by a complex T suppressor (Ts) cell circuit. Induction of TDH cells requires Ia+ adherent cells as antigen-presenting cells. Little is known about the antigen presentation of the induction of Ts cells. We describe an experimental model in which TDH and Ts cells are induced separately by different antigen-presenting macrophages grown from bone marrow stem cells. Bone marrow derived macrophages grown in L cell-conditioned medium for various periods and labeled with 2,4-dinitrobenzene sulfonic acid differ in their ability to induce TDH and Ts cells in vitro. The functional activity of the two T subpopulations was assessed in vivo by epicutaneous challenge or sensitization with 2,4-dinitrofluorobenzene of mice receiving the in vitro educated cells. Ear swelling or suppression of swelling was recorded. It could be shown that 5-7 day bone marrow-derived DNP-labeled macrophages preferentially induced Thy 1+ Lyt 1+ antigen-specific TDH cells; 7-10 day old antigen-presenting bone marrow-derived macrophages induced preferentially Thy 1+ Lyt 2+ antigen specific Ts cells. Characterization of various phenotypic markers revealed different surface antigen expression and functional differences such as MIF responsiveness or transglutaminase activity on the two macrophage populations. These data support the concept that activation of the Ts regulatory circuit may require antigen presentation by specialized antigen presenting cells, characterized by certain surface and functional markers and different from those inducing preferentially TDH cells.

Animals↗
PubMed1984

Inhibition of the T suppressor circuit of delayed-type hypersensitivity by interferon.

The effects of electrophoretically pure murine interferon (Mu-IFN-alpha beta) on the T suppressor pathway and on the T effector cell of delayed hypersensitivity (TDH) were investigated in BALB/c mice, in a 2,4-dinitrofluorobenzene (DNFB) contact-sensitivity model. Various T cell subpopulations, suppressor T cells of the afferent (Ts-aff) and efferent (Ts-eff) types, an auxiliary Ts (Ts-aux), as well as TDH were induced, and their function was assessed in transfer experiments. The results were as follows. At a dose of 5 X 10(3) U, IFN was shown to inhibit the Ts-aff response, when given to the donor animal shortly after induction of the Ts-aff subpopulation or when injected into the recipient 2 hr after spleen cell transfer. Pretreatment in vitro with IFN of the splenic cells to be transferred also abolished the Ts-aff response. Similar amounts of IFN were able to inhibit the generation of Ts-eff in the donor animals, whereas 10-fold-higher amounts were needed in vivo or in vitro to block the functional expression of Ts-eff in the recipient animal. Intravenous injection of IFN into recipients of Ts-eff on day 0 and 1 after sensitization inhibited the expression of the Ts-eff transferred 1 day before ear challenge. This suggests that the Ts-aux response required for the TDH suppression by Ts-eff is blocked by IFN. Secretion of a suppressor factor by Ts in vitro was not blocked by IFN. Treatment of the donor of suppressor factor-secreting Ts with IFN, however, blocked the induction of this Ts. The TDH were not sensitive to IFN even at amounts approximately 100 times higher than those used for the Ts inhibition in vivo as well as in vitro. These results demonstrate that low amounts of IFN may selectively block the suppressor pathway, because induction of these regulatory T cell subsets appears to be particularly sensitive to IFN. The exact mechanism of the IFN-mediated inhibition of Ts is not yet clear. The data suggest an important regulatory function of IFN in delayed-type hypersensitivity (DTH) reactions.

Animals↗
PubMed1984

[Immunologic principles of allergic contact eczema].

Epicutaneous sensitization against contact allergens is mediated by T lymphocytes. For activation of these T lymphocytes antigen has to be presented in association with Ia by Langerhans cells. A further signal for activation of this cell is provided by interleukin 2. The production of interleukin 2 is induced by interleukin 1, which can be also produced by keratinocytes (epidermal T-cell activating factor, ETAF). The activated T-effector lymphocyte is controlled by T-suppressor lymphocyte subpopulations. The interaction between these cells is genetically controlled. A defect in this genetic control may play a role in contact sensitization against various allergens.

B-Lymphocytes↗
PubMed1984

[Late results in the treatment of subtalar dislocations].

A follow-up study concerning arthrotic, ischemic and functional results was performed in 20 patients with subtalar luxations over an average of 13 years after the initial trauma. 13 patients showed good, 7 poor results according to Weber. 4 of these 7 patients were free of any complaints but showed reasonable arthrosis in both ankle joints as well as pathological scintigrams. Three cases operated upon showed poor functional results, two of them were primarily open, in one case the tendon of m. tibialis post. forced us to reduct openly. The best results could be obtained by immediate reduction and conservative treatment.

Adult↗
PubMed1983

The EEG after alcohol administration in men at risk for alcoholism.

The biologic sons of alcoholics constitute a group at high risk (HR) for alcoholism. A 0.5-g/kg dose of alcohol was administered to HR and control subjects aged 19 to 21 years. Blood alcohol concentration measurements failed to distinguish HR from control subjects, but quantitative measurements of EEG alpha activity differentiated them. The HR subjects exhibited greater increases in slow alpha energy and greater decreases of fast alpha energy after alcohol administration than controls; the HR subjects also showed greater decreases in mean alpha frequency after alcohol administration. These EEG findings suggest that subjects at high risk for alcoholism are physiologically more sensitive to alcohol than control subjects.

Adult↗
PubMed1983

Possibilities for retrieving temporal information in MEDDOK retrieval system.

This paper describes shortly some aspects of the MEDDOK retrieval language especially the methods for making vertical retrieval. In addition the question is investigated how this retrieval can be done without scanning and searching most of the data pool. Another subject of the paper is the description of the underlying data structure.

Computers↗
PubMed1983

Anti-P. acnes antibody in comedonal extracts.

Extracts of comedonal material obtained from patients with acne vulgaris were analyzed for albumin, IgG, IgM, IgA, and anti-Propionibacterium acnes antibodies using immunodiffusion and anti-immunoglobulin hemagglutination tests. Extracts were obtained from comedones of patients with (1) comedonal, (2) papulopustular, (3) nodular-cystic, (4) "burned out" acne, (5) patients under oral tetracycline treatment, and (6) with pustules. In all comedonal extracts analyzed, albumin and IgG (ratio approximately 1:2.5) could be detected. IgM, IgA, and C3 could not be found in noninflamed comedones by the techniques used; pustules, however, contained all immunoglobulin classes and albumin in ratios found in serum as well as C3. The anti-P. acnes antibody activity in the comedonal extracts was associated with the IgG class. Immunofluorescence microscopical examination of material from single comedones obtained by the cyano-acrylate technique showed IgG antibody on rod-shaped bacteria. The amount of IgG and albumin in comedonal extracts from the various patient groups was not different. It is concluded that IgG (and antibody of the IgG class) in comedones is derived from the serum and selectively accumulated in the follicle by an unknown mechanism.

Acne Vulgaris↗