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Biomedical subjects

J Brock

Publications and source records attributed to J Brock.

At least 91 records · Page 5Linked to original sources
PubMed1990

Relationship between internalization kinetics and cytotoxicity of mistletoe lectin I to L1210 leukaemia cells.

We have taken two different approaches to the study of the entry of mistletoe lectin I (MLI) into murine L1210 leukaemia cells. As detected by cellular protein synthesis and DNA synthesis inhibition, the lectin was cytotoxic to L1210 leukaemia cells. Inhibition of [3H]leucine and [3H]thymidine incorporation into L1210 cells by MLI was found dose dependent in a concentration range from 10(-16) to 10(-12) mol/ml. The kinetics of cellular protein synthesis inhibition by MLI was concentration dependent, too. Using preembedding electron microscopy, the binding and intracellular routing of the gold-labelled lectin (MLI.Au15) were studied. MLI was internalized into L1210 leukaemia cells by two different pathways: via coated pits to coated vesicles and via long enclosed invaginations of the plasma membrane.

Animals↗
PubMed1989

Internal densitometric gating for digital subtraction angiography.

Motion artifacts create a severe problem in digital subtraction angiography (DSA) studies. Periodic motion can be eliminated by "gating," matching a precontrast mask with a postcontrast image at the same phase position in the cycle. Electrocardiogram (EKG) signals are used in cardiac DSA for this purpose. An alternate method relies on the generation of a density-time curve dependent on the attenuation changes of anatomical motion. A densitometric window placed at an appropriate location records the variation, from which individual images are tagged with phase position information encoded as delay time. Results are similar to the EKG gating method for cardiac DSA when using an appropriate window location. Periodic motion caused by superimposed respiration can be suppressed by tracking diaphragm or other object attenuation changes with the same algorithms. Using these techniques permits the nonarbitrary matching of mask and contrast images without physiologic monitoring. The techniques are straightforward and relatively easy to implement on systems designed for rapid digital imaging.

Angiography↗
PubMed1989

Superior mesenteric artery vasoactivity in hyperlipidemic Watanabe rabbits versus normal lipidemic New Zealand controls.

Recent in vitro studies on isolated coronary and mesenteric arteries have shown that hyperlipidemia appears to hypersensitize the vascular arterial smooth muscle to drugs such as ergonovine and that this increased contractility seems to be mediated by a serotinergic mechanism. This results in vasospasm with exposure to certain vasoactive drugs such as serotonin or norepinephrine. However, in vivo quantification of this observed phenomenon has not been done. In the present study we used Watanabe hereditary hyperlipidemic (WHHL) rabbits (cholesterol level 459 +/- 216 mg/dL) and the normal lipidemic New Zealand white (NZW) rabbit (cholesterol level 35 +/- 19) as a control in the study of hyperlipidemia and blood flow changes in response to various vasoactive drugs. Blood flow measurements were made by the video dilution technique (VDT) following catheterization of the superior mesenteric artery. The serotinergic vasoactive drug ergonovine maleate was injected into the superior mesenteric artery at low dose (0.002) mg/kg) and high dose (0.004 mg/kg). A significant decrease (p less than .05) in blood flow was observed in response to high-dose ergonovine maleate in WHHL rabbits compared to the NZW rabbits. This in vivo experiment confirms the in vitro studies showing that hyperlipidemia sensitizes mesenteric arteries in the presence of serotinergic stimuli. The vasodilators verapamil hydrochloride and calcitonin gene-related peptide (CGRP) injected into the superior mesenteric artery caused a marked increase in flow in both the WHHL and the normal lipidemic NZW rabbits. This model can be used in the assessment of superior mesenteric artery ischemia and its reversal.

Animals↗
PubMed1989

[Secretory immunoglobulin A (sIgA) in parotid saliva of patients with cystic fibrosis].

Investigations of immunoglobulin concentrations--especially of secretory IgA (sIgA)--were performed in isolated parotid saliva samples by means of a modified Mancini technique considering the structural specialties of sIgA. The measurement of flow rates under continuous stimulation of parotid gland secretion by citric acid allowed calculations of glandular output. Cystic fibrosis patients showed decreased secretion rates of sIgA during gland secretion stimulation. Because parotid glands and bronchial glands are parts of BALT, we can conclude, that a functional sIgA deficiency is a pathogenetic factor under others in chronic bronchopulmonary infections of cystic fibrosis patients.

Adolescent↗
PubMed1989

Detection and quantification of ligand leakage from lectin affinity columns.

The usefulness of lectin affinity chromatography for the preparation of glycoproteins is impaired by ligand release. Ligand leakage from mistletoe lectin (MLI) Sepharose 4B column was detected by 24 h skin reaction in mice and by immunoblotting. Immunoaffinity chromatography was found to be an efficient method for the separation of lectin traces from the glycoprotein fraction. A sugar concentration dependent increase of lectin release from MLI-Sepharose 4B column was detected by a solid phase enzyme immunoassay.

Animals↗
PubMed1988

Secretory immunoglobulin A (sIgA) in the serum of cystic fibrosis patients.

Clearly increased sIgA values were found in cystic fibrosis patients in more than 70%. The highest concentrations were seen in patients with obstructive liver disease. There were no correlations between sIgA and liver-associated enzymes. Postmortem histology and sIgA correlated well. These data suggest a pertinent role of sIgA assessment in evaluation of hepatic involvement in cystic fibrosis.

Adolescent↗
PubMed1988

The binding of IgG1 containing immune complexes to the FcR of allogenically activated T cells induces changes in the membrane potential and the cell surface charge.

The effect on membrane potential and cell surface charge of binding immune complexes containing IgG1 and IgG2a monoclonal antibodies to Fc receptors was studied in resting and allogenically activated murine T cells. IgG1 complexed by antigen or heat aggregation induced electrophysiological changes on activated T cells. A biphasic alteration of membrane potential was detected by measurement of the intra- and extracellular distribution of the fluorescent dye, DiOC6. A short-lived hyperpolarization, detectable for 4-6 min after adding the respective ligand, was followed by a longer lasting depolarization. The cell surface charge, measured by cell electrophoresis, was also changed. This alteration was detected 2-4 hr after addition of immune complexes and disappeared by the 8th hr of incubation. Monoclonal antibody 2.4.G2, reactive with mouse FcR, induced a similar membrane potential response on activated T cells, but did not affect the cell surface charge. Monomeric IgGs and complexes of IgG2a did not modify these parameters. FcR ligands had no effect on the studied characteristics of resting T cells.

Animals↗
PubMed1988

Clinical evidence of secretory IgA and Schwangerschaftsprotein 1 in pleural effusions of lung cancer patients.

Secretory immunoglobulin A, alpha 1-fetoprotein, orosomucoid and alpha 2-macroglobulin have been estimated in pleural effusions of 11 lung cancer patients. Secretory immunoglobulin could be detected in all cancer patients except one with a secondary embolism. Levels could be found between 0.19 and 0.73 g/l. No SIgA could be detected in a control group of 7 patients with pleural effusions of other origin.

Enzyme-Linked Immunosorbent Assay↗
PubMed1988

[Functional capacity of T cell subpopulations in mice. II. Effect of allogeneically stimulated T-cell subpopulations on the primary MLR].

The effect of allogeneically stimulated lymphocytes or their subpopulations respectively on a primary allogeneic MLC was studied. It was shown that this effect depends either on the amount of the transferred cells or on the composition of the culture medium. In contradiction to the common view that allogeneically stimulated lymphocytes act as suppressor cells, a significant stimulating effect, mediated by these cells, could be demonstrated under respective conditions. Also in the experiments with the subpopulations of allogeneically stimulated lymphocytes the effects of these cells are rather influenced by the conditions then determined by a restricted functional repertoire of the cells.

Animals↗
PubMed1988

[The binding behavior and functional significance of Fc receptors for IgG on T lymphocytes of the mouse].

In consequence of allogenic stimulation of mouse spleen lymphocytes the binding of fluorescein isothiocyanate conjugated aggregated IgG (FITC-aggr. IgG) per cell is increased (higher affinity of receptors and/or higher number of receptors). A higher specificity of the FITC-aggr. IgG binding to allogeneically stimulated lymphocytes in comparison to fresh prepared resting and syngeneically cultivated lymphocytes could be only detected on the higher fluorescing allogeneically stimulated cells. Increased amount of Fc-receptors for IgG (Fc gamma R) is mainly found on T-lymphocytes with the Lyt-1 + 2 +-phenotype. The manipulation of that Fc gamma R on T-lymphocytes, which were expressed in consequence of allogeneic stimulation by binding of respective ligands, did not change the original effect of nonmanipulated, allogeneically activated cells on a primary MLR. But if the cells were negatively selected by means of monoclonal antibodies and complement, the originally suppressive effect of allogeneically stimulated Lyt-2 positive cells on a primary MLR was abolished by manipulating the respective Fc gamma R.

Animals↗
PubMed1988

Cell mediated and humoral immunity and light-chain proteinuria in rifampicin-treated tuberculous patients.

The present study was devoted to assess the humoral and cell mediated immune responsiveness in patients with pulmonary tuberculosis before and after rifampicin therapy. Skin test using PPD and PHA; Rosette forming cells test, serum IgG, M and A; and light chain proteinuria have been tested for 15 newly diagnosed tuberculous patients and 15 normal controls. Rifampicin showed an immunosuppressive effect on both cellular and humoral immune responses as well as by the advent of light chain proteinuria.

Humans↗
PubMed1988

[Functional capacity of T-cell subpopulations of the mouse. Effect of unstimulated and allogenic stimulated T-cell subpopulations on Con A stimulation of splenic lymphocytes].

The distribution and the functional capacity of special subpopulations was examined by means of monoclonal anti-Lyt-1.2-, anti-Lyt-2.2-, anti-L3T4- and anti-Thy-1.2-antibodies. The proportion of Lyt-2+-cells increased after allogeneic stimulation of spleen cells compared with the Lyt-1+-cells. The proportion of L3T4+-cells did not change by allogeneic stimulation. Lyt-2- cells which were negatively selected by monoclonal antibody and complement effected the Con A stimulated 3H-thymidine incorporation of a spleen cell culture in a different way depending on their state of differentiation. While Lyt-2--cells selected from a fresh prepared spleen cell suspension increased the 3H thymidine incorporation, Lyt-2--cells selected from allogeneically stimulated cell suspension act as suppressor cells. The results demonstrate the dynamics in the functional capacity of the Lyt-2--T cell subpopulation depending on their state of differentiation.

Animals↗
PubMed1987

Suppression of GvHR by in vitro allogeneically stimulated lymphocytes: the role of lymphoblasts in the regulation of a primary T-cell response.

Graft versus host reaction (GvHR) induced in 10-day-old F1 mice by in vitro allogeneically or mitogenically stimulated spleen cells is lower than that induced by unstimulated fresh spleen cells. In vitro stimulated lymphoblasts are unable or only slightly able to induce a GvHR. An active suppression by the blasts is not involved. Since lymphoblasts after in vivo stimulation show an increased ability to elicit a GvHR it is concluded that in vitro and in vivo stimulated lymphoblasts have different properties. A different homing cannot be excluded after transfer to the mouse.

Animals↗
PubMed1987

Development of lumbar spinal cord and cortical evoked potentials after tibial nerve stimulation in the pre-term newborns: effects of gestational age and other factors.

Pre-term neonates are at increased risk for neurological dysfunction. Several investigators have found scalp recorded somatosensory evoked potential studies (SSEPs) after median nerve stimulation useful in the evaluation of newborn infants with asphyxiation and the effects of other adverse prenatal and perinatal factors. In order to evaluate the entire developing neuraxis, we undertook SSEPs after tibial nerve stimulation (PTN-SSEP) in pre-term neonates. Using bilateral simultaneous stimulation, potentials were recorded from the following sites: PF-spT6 (N5), spL1-spT6 (N16), spC7-Fpz (N27), Cz' (1 cm behind the vertex)-Fpz (P55). In all newborns studied, the N5 and N16 were reliably recorded. The N5 appeared relatively independent of the length of the newborns. The N16 correlated inversely with length. The N27 and P55 were recorded in 52% and 65% of the newborns, respectively. N27 inversely correlated modestly with length. The P55 was independent of most factors and probably reflects variable rates of cerebral myelination, neuronogenesis, varying states of alertness, and possibly subclinical encephalopathies. These results demonstrate the feasibility of obtaining such data in pre-term newborns.

Brain↗
PubMed1987

[Significance of Fc receptors for IgG].

Fc gamma R are glycoproteins or phospholipoproteins respectively. Their molecular weight depends on type and origin of the Fc gamma R-coated cell and was determined between 40 and 115 KD. Fc gamma R can be estimated by means of rosetting assay or binding experiments with isotopic or fluorescein labeled immune complexes or aggregated IgG respectively. Depending on the cell type Fc gamma R are involved in different reactions after respective binding of their ligands. A lot of results are described in the literature, indicating that Fc gamma R bearing T lymphocytes are suppressor cells in the humoral immune response, but generally accepted data about the involvement of Fc gamma R in this suppression do not exist. Some models are represented in this paper.

Humans↗
PubMed1987

Suppression of cell proliferation after incubation of allogeneically stimulated mouse lymphocytes with concanavalin A: serological analysis of cell subpopulations involved.

The effect of Con A incubation of allogeneically stimulated lymphocytes (a-MLC) on cell proliferation was tested in three experimental systems: in the a-MLC cell population itself; after transfer of a-MLC cells to a culture of normal spleen cells with Con A; and after transfer of supernatants from cultures of a-MLC cells with Con A to fresh cultures of normal spleen cells with Con A. It was found that incubation with Con A to fresh cultures of normal spleen cells with Con A. It was found that incubation with Con A caused inhibition of cell proliferation in all three systems, indicating the generation of suppressor cells by incubation of a-MLC cells with Con A. The suppressive activity was abolished by cytotoxic treatment with either anti-Thy-1 or anti-Lyt-1 monoclonal antibodies, but neither with anti-L3T4 nor with anti-Lyt-2 antibodies, in all three systems.

Animals↗
PubMed1987

[Relations between concanavalin A binding and cell proliferation. Comparison of Lyt-1+ and Lyt-2+ lymphocyte subpopulations from the spleen of unstimulated mice and mixed lymphocyte culture].

Fluorescein isothiocyanate conjugated concanavalin A (FITC-Con A) binding to negatively selected Lyt-1+ and Lyt-2+ spleen cells from nonstimulated mice and from mixed lymphocyte culture (MLC) was tested in parallel with the effect of Con A on proliferation of these cell subpopulations. Lyt-2+ spleen cells from nonstimulated mice bound more FITC-Con A but proliferated in response to Con A to lesser extent than Lyt-1+ cells. allogeneically stimulated Lyt-1+ cells were inhibited by Con A and bound FITC-Con A in higher amounts and more specifically than Lyt-2+ cells. In syngeneic control culture, no remarkable differences in both Con A binding and Con A-induced proliferation of the lymphocyte subpopulations were found. The results are discussed in context of Lyt-phenotypic and functional differences between T cell subpopulations and seem to contradict a strict correlation between Con A binding and cell function.

Animals↗