Safety, regulation and innovation in the food sector.
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Biotechnology↗
Biomedical subjects
D Jonas
Publications and source records attributed to D Jonas.
Choice of soft pulse shapes for signal excitation in chemical shift selective imaging.
The choice of soft pulse shapes for chemical shift selective excitation in chemical shift imaging is discussed. In the presence of inhomogeneities in the static magnetic field resulting from susceptibility anomalies, it is important to optimise pulse bandshape and frequency offset as well as bandwidth, in order to minimize artefacts arising from excitation of unwanted resonances. A comparison of the use of Gaussian and sinc shaped excitation pulses in the chemical shift micro-imaging of grapes serves to illustrate some of the effects that may be observed.
Magnetic Resonance Spectroscopy↗
Enzyme-linked immunoassay for detection of PCR-amplified DNA of legionellae in bronchoalveolar fluid.
A nonradioactive method is described that detects 10 to 100 legionellae in 1 ml of bronchoalveolar lavage fluid. DNA is purified by a proteinase K-phenol protocol or with a commercial DNA preparation kit and amplified by PCR with amplimers specific for the 16S rRNA gene of Legionella pneumophila. The upstream primer is 5' biotinylated. The amplification product is immobilized on streptavidin-coated microtiter plates. Because of the high binding capacity, no removal of nonincorporated biotin from the PCR product is required. After alkaline denaturation, the single-stranded PCR product is hybridized with a 5' digoxigenin-labeled probing oligomer. The amplification product is then detected by using peroxidase-labeled anti-digoxigenin antibodies in a luminescence or colorimetric reaction. The assay detects as few as 10 legionellae in 1-ml bronchoalveolar lavage fluid specimens. It is specific for medically relevant Legionella species, including Legionella pneumophila, L. bozemanii, and L. longbeachae. Of over 250 clinical specimens examined, 8 were positive for legionellae by both culture and the PCR assay. Six further specimens were culture negative but PCR positive for legionellae; of these, five specimens were from patients receiving high-dose erythromycin therapy for suspected or previously diagnosed legionella pneumonia. None of the remaining 240 specimens that were culture negative for legionellae yielded a positive PCR test, although a total of over 30 different bacterial species were cultured from these specimens. The PCR assay therefore appears to exhibit high sensitivity and specificity and thus could prove suitable for use in the routine microbiological diagnostic laboratory.
Base Sequence↗
Multi-dimensional visualisation of laboratory findings and functional test results for analysing the clinical course of disease in medicine.
The illustration of a patient's history by a graphical primitive is discussed. Illustration technology is presented which simultaneously represents quantitative examination findings (e.g., laboratory values) and qualitative findings (e.g., from function diagnostics) by a single geometrical figure. Depending on the medical results, this figure takes on characteristic forms which can be identified as patterns typical for a specific disease. The procedure developed is integrated in a user interface which is implemented in the form of a computerized medical record for use on a pentop computer. This portable computer assists the physician during ward rounds, supplies additional, intelligence-based information, serves quality control, and streamlines working procedures making them more efficient.
Clinical Laboratory Information Systems↗
[Intraoperative localization of metastases with a hand-held gamma probe].
A 50-y-old male patient with prostate cancer showed two suspicious lesions in bone scintigrams. They were assessed to be bone metastases by biopsy of the os ilium. After i.v. injection of 99mTc-HMDP a probe-guided localization permitted optimal surgical treatment. A bone metastasis in the os ilium was confirmed. The intraoperative detection with a hand-held gamma probe permitted accurate and complete excision of the tumour; the bone defect could thus be reduced to a minimum.
Bone Neoplasms↗
Recovery of human fibroblasts from attack by the pore-forming alpha-toxin of Staphylococcus aureus.
When applied at low concentrations (< 10 micrograms/ml), staphylococcal alpha-toxin generates a small channel in keratinocyte and lymphocyte membranes that permits selective transmembrane flux of monovalent ions. Here we show that a moderate concentration (1-50 micrograms/ml) of alpha-toxin similarly produces a small pore in membranes of human fibroblasts. This process leads to rapid leakage of K+ and to a drop in cellular ATP to 10-20% of normal levels in 2 h. In the presence of medium supplemented with serum and at pH 7.4, the cells are able to recover from toxin attack, so that normal levels of K+ and ATP are reached after 6-8 h at 37 degrees C. The repair process is dependent on the presence of serum in the medium and is very sensitive towards pH. Decreases of pH in the medium to < or = 7.0 as well as increases to > or = 7.8 causes the repair mechanism to fail. The fate of cell-bound toxin molecules was investigated by using a radiolabelled tracer and by immunological detection of toxin exposed at the cell surface. The results indicated that 50-70% of the toxin was shed from cell membranes. However, there was no clear correlation between shedding and recovery, and shedding was also observed in cells that died at pH 7.8. Shedding was not decisive for repair, since cells that had recovered from toxin attack continued to carry 30-40% of initially bound toxin on their cell surface. Blockade of Na+/K(+)-ATPases with ouabain evoked similar kinetics of K(+)-depletion in control cells, compared with cells that had just recuperated from toxin attack and that still carried 30-40% alpha-toxin on their surface. We therefore tentatively concluded that repair of alpha-toxin lesions was due to closure of small pores, rather than from compensation of membrane leaks by up-regulation of Na+/K(+)-ATPase activity. We speculate that repair of small membrane lesions may extend to other agents that produce channels of similar nature in nucleated cells. Larger pores created by E. coli hemolysin or streptolysin O, both of which form larger functional transmembrane lesions, could not be repaired by fibroblasts.
Adenosine Triphosphate↗
Novel path to apoptosis: small transmembrane pores created by staphylococcal alpha-toxin in T lymphocytes evoke internucleosomal DNA degradation.
Peripheral-blood human T lymphocytes were treated with Staphylococcus aureus alpha-toxin. Membrane permeabilization was assessed by measuring efflux of K+ and Rb+ and influx of Na+, Ca2+, and propidium iodide. Cellular ATP and [3H]thymidine incorporation following lectin stimulation were measured as parameters for cell viability. Internucleosomal cleavage characteristic of programmed cell death was assessed by agarose gel electrophoresis and by quantifying low-molecular-weight, [3H]thymidine-labeled DNA fragments. Nanomolar concentrations of alpha-toxin evoked protracted, irreversible ATP depletion in both activated and resting T lymphocytes. Toxin-damaged cells also lost their ability to incorporate [3H]thymidine upon subsequent stimulation with phytohemagglutinin. These cells carried toxin hexamers, and their plasma membranes became permeable for monovalent ions but not for Ca2+ and propidium iodide. The permeabilization event was followed by internucleosomal DNA degradation characteristic of programmed cell death. Membranes of cells treated with high toxin doses (> 300 nM) became permeable to both Ca2+ and propidium iodide. In this case, ATP depletion occurred within minutes and no DNA degradation was observed. When cells were suspended in Na(+)-free buffer, alpha-toxin applied at low doses still bound and formed hexamers. However, these cells displayed neither DNA degradation nor loss of viability. The data indicate that formation of very small but not of large alpha-toxin pores may trigger programmed cell death in lymphocytes and that uncontrolled flux of Na+ ions may be an important event precipitating the suicide cascade.
Adenosine Triphosphate↗
Monoclonal antibody 138H11 in immunoscintigraphy of human kidney tumors--in vitro results.
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Adenocarcinoma↗
Daily alternating administration of high-dose alpha-2b-interferon and interleukin-2 bolus infusion in metastatic renal cell cancer. A phase II study.
BACKGROUND: Both interleukin-2 (IL-2) and alpha-interferon (alpha-IFN) have some efficacy in renal cell cancer (RCC) as single agents. Additionally, there is some evidence for additive or synergistic antitumoral activity of IL-2 and alpha-IFN in vitro and possibly in vivo. Based on these data, the authors initiated a Phase II trial with a combination of recombinant IL-2 (rIL-2) and recombinant alpha-IFN (alpha-rIFN) in advanced RCC. METHODS: Thirty-six assessable patients with metastatic RCC were entered in this Phase II trial using a daily alternating schedule of alpha-rIFN and rIL-2. Over a period of 14 days, the patients received daily alternating treatment with 10 x 10(6) IU/m2 of recombinant alpha-2b-interferon subcutaneously and 18 x 10(6) IU/m2 of rIL-2 as a 1-hour intravenous infusion. This treatment schedule was repeated every sixth week up to a maximum of four cycles. After the second cycle, patients were examined for response. Patients with stable disease or better received two additional cycles of therapy. Patients with progressive disease were available for other strategies. RESULTS: Thirty-six patients entered the trial and were assessable for toxic effects. Thirty of 36 patients completed at least two cycles and were assessable for response. Nine patients achieved an objective response: 2 had complete responses (CR) and 7 had partial responses (PR). Three patients had a minor response. No effect was observed in patients with local relapse or bone metastases. A relapse-free survival length of 6 months or longer was seen in both patients with CR (12, 23 + months) and in four of seven patients with PR (6, 7, 12, 12 months). The toxicity was moderate and included fever and nausea in most patients, and hypotension, fatigue, skin rash, and arthralgia in a minority of the patients. No Grade 4 and only occasionally Grade 3 toxicity was observed. Fluid retention was negligible. The monitoring of immunologic parameters showed a significant rebound lymphocytosis including cytotoxic (CD56+) cells; in responders the peak of lymphocytosis occurred up to 1 week later than in nonresponders. Peripheral lymphocytes obtained after therapy showed only a slight increase of natural killer cell and lymphokine-activated killer cell activity. During therapy, there was a great release of secondary cytokines as tumor necrosis factor-alpha, gamma-interferon, and interleukin-6, with a peak level 2-4 hours after rIL-2 infusion. CONCLUSIONS: In conclusion, daily alternating administration of alpha-rIFN and rIL-2 is effective in RCC with less toxicity, and the response rate is comparable to those of other immunotherapeutic schedules, including adoptive immunotherapeutic schedules, including adoptive immunotherapy and combinations of high-dose IL-2 and alpha-IFN.
Aged↗
Properdin, a positive regulator of complement activation, is expressed in human T cell lines and peripheral blood T cells.
Properdin plays an important regulatory role in the activation of the complement system. Here we report the biosynthesis of properdin in four different human T cell lines and in T cells purified from peripheral blood. Cell sorting experiments, in conjunction with Northern blotting, showed that both CD4- and CD8-bearing populations of T cells have the potential to synthesize properdin. The functional activity of properdin secreted from these T cell lines was determined in a hemolytic assay. In view of the numerous ways in which complement activation may influence cellular immune response, the present results indicate, for the first time, a possible interaction between the complement and the T cell system.
Adult↗
A guide to the use of pore-forming toxins for controlled permeabilization of cell membranes.
Depending on the size of the pores one wishes to produce in plasma membranes, the choice will probably fall on one of the three toxins discussed above. S. aureus alpha-toxin should be tried first when pores of 1-1.5 nm diameter are required. This is generally the case when Ca2+ and nucleotide dependence of a given process is being studied. If alpha-toxin does not work, this is probably due to the fact that the toxin either does not produce pores, or that the pores are too small. In this case, high concentrations of alpha-toxin should be tried. If this still does not work, we recommend the use of HlyA. When very large pores are to be created, e.g. for introduction of antibodies into the cells, SLO or another member of this toxin family are the agents of choice. SLO preparations need to be checked for presence of protease contaminants. Tetanolysin currently offers advantages since it is protease-free, and the size of the pores can probably be controlled by varying the toxin dose. Methods for assessing the size of pores created by such agents have been published in the recent literature, and the appropriate papers can be consulted whenever the need arises.
Bacterial Proteins↗
Staphylococcal alpha-toxin kills human keratinocytes by permeabilizing the plasma membrane for monovalent ions.
Incubation of human keratinocytes with nanomolar concentrations of Staphylococcus aureus alpha-toxin leads to irreversible depletion of cellular ATP. The toxin forms hexamers in the target cell membranes, and rapid transmembrane flux of K+, Na+, and 86Rb+ is observed. Unexpectedly, pores formed in keratinocytes through application of low but lethal doses of alpha-toxin appeared to be considerably smaller than those formed in erythrocyte membranes. They permitted neither rapid influx of Ca2+ or propidium iodide, nor efflux of carboxyfluorescein. Larger pores allowing flux of all three markers did form when the toxin was applied at high concentrations. Flux of monovalent ions and reduction in cellular ATP levels evoked by low toxin doses correlated temporally with a fall in oxygen consumption, which was interpreted to reflect breakdown of mitochondrial respiration. The lethal event could not be thwarted by manipulating the extracellular K+ or Ca2+ concentrations. Realization that alpha-toxin may form very small pores in nucleated cells is important for future research on cellular toxin effects and membrane repair processes.
Bacterial Toxins↗
Cytocidal effects of Escherichia coli hemolysin on human T lymphocytes.
Escherichia coli hemolysin is the prototype of a large family of pore-forming toxins produced by gram-negative organisms. Besides its known cytotoxic activities against granulocytes, monocytes, endothelial cells, and renal epithelial cells, we now demonstrate that the toxin potently kills human T lymphocytes. Evidence based on different and independent approaches indicates that lymphocidal activity is due to formation of transmembrane pores. Additionally, cells prestimulated with phytohemagglutinin respond to low doses of E. coli hemolysin with DNA fragmentation similar to that observed in cells undergoing programmed cell death. Kinetic considerations lead us to conclude that DNA degradation may, however, represent an epiphenomenon. Killing of T cells is another means through which E. coli hemolysin could directly impair host defense.
Adenosine Triphosphate↗
[Immunoscintigraphy in inflammatory and malignant diseases. anti-leukocyte and anti-tumor antibodies].
Antibody-labelled granulocytes, antigranulocyte antibodies and radiolabelled immunoglobulin can reliably visualize foci of infection; their use in urologic inflammatory disorders is rare. In the diagnosis of urologic tumours anti-CEA immunoscintigraphy of urinary bladder cancer seems to be superior to conventional imaging techniques in sensitivity and specificity. Experience with immunoscintigraphy in non-seminomatous germ cell tumours and prostate cancer are limited; immunoscintigraphy of renal cell cancer is still in the experimental stage in clinical medicine.
Antibodies, Monoclonal↗
[Follow-up after kidney transplantation. Sequential functional scintigraphy with technetium-99m-DTPA or technetium-99m-MAG3].
Complications following renal transplantation are associated with transplant dysfunction; their frequency and the nonspecificity of clinical symptoms underscore the importance of choosing the correct diagnostic procedure. Sequential function scintigraphy with technetium-99m-MAG3 is noninvasive and facilitates the diagnosis of different types of organ rejection, of drug-induced malfunction and of surgical complications.
Graft Rejection↗
Clonal analysis of bcr-abl rearrangement in T lymphocytes from patients with chronic myelogenous leukemia.
The cytogenetic hallmark of chronic myelogenous leukemia (CML) is the Philadelphia chromosome (Ph1), which reflects a chromosomal translocation t(9;22) and a rearrangement of the ABL and bcr genes. This marker is found in all cells arising from the same malignant precursor cell and can be detected in CML cells of the myeloid, monocytic, erythroid, and B-lymphocyte lineage. It is, however, controversial as to whether T lymphocytes of CML patients carry this gene rearrangement. An answer to this question would clarify whether the translocation in CML occurs in a pluripotent hematopoietic stem cell or in a precursor cell already committed to certain lineages, but not the T-cell lineage. To address this question, we established T-cell clones from peripheral venous blood cells of four patients with CML and screened these clones for bcr-abl fusion transcripts by means of polymerase chain reaction and Southern blot analysis. In four T-cell clones of three of these patients, the bcr-abl transcript could be detected. None of 12 T-cell clones of the fourth patient disclosed detectable bcr-abl amplification product. Both CD4+ as well as CD8+ clones displayed fused bcr-abl sequences. These data imply that in CML some but not all T lymphocytes may originate from the Ph1-positive stem cell.
Blotting, Southern↗
[The electromotor unit of the upper urinary tract].
The muscular architecture of the upper urinary tract constitutes a functional but no anatomical syncytium, where the cells are coupled by nexus and crosslinking with low electrical resistance. The action potentials are evoked by spontaneous depolarisation of muscle cells. The sites of peak depolarisation could be termed pace-maker cells. They are localized in the calices. Recent studies have, however, described myofilaments capable of contraction in the proximal tubuli already. Volume and pressure loads on the hollow system have been identified as the regulation mechanism. Modulatory function is directly related to evidence of alpha- and beta-adrenergic receptors, of receptor subtypes, of the adenylate cyclase system, of histamine- and possibly prostaglandin- and serotonin-receptors as well.
Animals↗