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Biomedical subjects

K Schauenstein

Publications and source records attributed to K Schauenstein.

At least 19 recordsLinked to original sources
PubMed1997

Melatonin and the immune system.

In recent years, melatonin, i.e. the major endocrine product of the pineal gland, was investigated as to its possible regulatory role in the communication between the neuroendocrine and the immune systems. First indications that melatonin may be an endocrine immunomodulator came from early reports about antitumor effects in animals and humans. Since then evidence has accumulated suggesting that melatonin-as a well-preserved molecule during evolution-is indeed involved in the feedback between neuroendocrine and immune functions. At present we begin to discover molecular mechanisms, by which melatonin affects cellular functions in general, and from the variety of possible direct and indirect interactions it appears that melatonin may play a complex physiological role in neuroimmunomodulation. In this article we want to give a critical review of the numerous reports on melatonin influencing immune functions, and to discuss the possible different mechanisms of action, which were suggested recently.

Animals↗
PubMed1996

Selective decrease in serum immunoglobulin G1. A tissue nonspecific tumor marker detecting early stages of gynecologic malignant disease with high efficiency.

BACKGROUND: Malignant diseases of various tissue origin have previously been found to be associated with a characteristic shift in the serum pattern of IgG subclasses, i.e., a highly significant reduction of the percent of IgG1 and an increase of the percentage of IgG2 relative to the total IgG. In the present study we examined the diagnostic performance of this indirect tumor marker in patients with carcinomas of various sites within the female reproductive tract. METHODS: Using quantitative affinity chromatography, the percents of IgG1 and IgG2 in the total IgG were determined for 207 patients with carcinoma of the ovary, cervix, or corpus uteri, prior to any treatment. The data were compared with those of 135 age matched healthy females and 52 patients with benign gynecologic diseases. RESULTS: It was found that (1) mean values for the percents of IgG1 and IgG2 of all of the cancer patients differed significantly from those of the patients with benign disease and healthy controls; (2) no differences were noted between carcinomas of the ovary, corpus or cervix uteri; (3) early stages of carcinoma exhibited the effect to the same extent as late stages; (4) the specificity of the percent of IgG1 to discriminate between controls and cancer patients ranged between 90 and 100%, regardless of localization and stage of tumor; and (5) whereas with ovarian cancer CA 125 showed a slightly greater sensitivity, the percent of IgG1 was by far more sensitive than the conventional markers CA 125, TPA, CEA, Ferritin, and SCC to diagnose carcinoma of the cervix and corpus uteri, notably at early stages. Combined analysis of the percent of IgG1 and CA 125 and/or TPA led to an increase in sensitivity with tumors of all three sites. CONCLUSIONS: Thus, the determination of the percent of IgG1 by itself and/or in combination with conventional markers may provide relevant information regarding the noninvasive detection of early stages of gynecologic carcinoma.

Adult↗
PubMed1996

Thymocyte-directed enhancement of apoptosis via soluble factor(s) derived from a cortical and a medullary thymic epithelial cell line.

Apoptosis of murine thymocytes was examined either in intact fetal thymus lobes or in thymus cell suspensions, both cultured alone or in the presence of either a cortical (TEC 1.4) or a medullary (TEC 2.3) thymic epithelial cell line. Both TECs induced a pronounced increase of apoptosis in 24-h cultivated single thymus cell suspensions but not in spleen or bone marrow cell cultures. Co-culture of thymocytes with murine fibroblasts did not enhance apoptosis of the thymus cells. A similar enhancement of thymocyte apoptosis was observed with dialysed culture supernatants derived from both TEC lines, the active component(s) having a molecular weight of > 30 kDa. In contrast, the cortical TEC 1.4 had a pronounced apoptosis inducing effect on intact fetal thymus lobes cultivated for six days, whereas the medullary TEC 2.3 had only a marginal influence. TEC 1.4 also induced a significant alteration in the ratio of CD4+CD8+ to CD4-CD8- cells. It is concluded that both the cortical and medullary epithelial cell lines are able to induce thymocyte apoptosis but that a large proportion of the cells within the intact thymus stroma is refractory to the respective signal(s) of the medullary epithelial cell line.

Animals↗
PubMed1996

Beta-blockade enhances adrenergic immunosuppression in rats via inhibition of melatonin release.

We have recently shown in rats that an in vivo treatment with catecholamines via alpha 2-receptors leads to a pronounced suppression of T- and B-cell mitogen responses of peripheral blood lymphocytes (PBL), provided that a beta-blocker is administered concomitantly. Since melatonin (MEL) reportedly has stress-protective effects on several immune functions, and since the release of MEL from the pineal gland is inhibited by beta-blockade, we tested the effect of MEL substitution on T- and B-cell mitogen responses of PBL in rats treated with two s.c. implanted retard tablets containing noradrenaline (NA) and propranolol. It was found that an oral treatment with MEL (about 40 micrograms/animal) abolished the adrenergic immunosuppression. Furthermore, functional pinealectomy induced by constant light had a similar enhancing effect on the alpha 2-adrenergic immunosuppression as observed with beta-blockers, whereas PBL from animals kept at the regular light/dark interval were resistant to the treatment with the selective alpha 2-agonist clonidine. It is concluded that endogenous MEL effectively protects rat PBL from adrenergic immunosuppression, and that beta-blockers enhance the immunosuppressive property of alpha 2-adrenergic agents via blocking the night-time release of MEL.

Adrenergic alpha-Agonists↗
PubMed1996

IgG1--as the only subclass of human serum IgG--spontaneously undergoes O2(-)-induced, noncovalent self-aggregation upon storage at room temperature.

An apparent gradual decrease of IgG1 serum levels of up to 40% occurs within 48 h of storage at room temperature. The effect does not concern any other IgG subclass, and is more pronounced in sera of smokers. A linear correlation was found between the extent of this "storage effect" and the initial concentration of IgG1, which rules out an enzymatic process following Michaelis-Menten kinetics. PAGE and Western blots of density gradient separated serum proteins revealed the presence of noncovalent self aggregates of IgG1 in stored sera. Addition of superoxide dismutase prevented both the formation of aggregates as well as the decay of IgG1 values. It is concluded that the instability of IgG1 is due to an enhanced propensity of this molecule to form self-aggregates, whereby O2(-)-radicals play a functional role. This mechanism, however, is not relevant to a previously detected selective decrease of relative IgG1 levels in sera of patients afflicted with malignant diseases of various tissue origin.

Blood Specimen Collection↗
PubMed1996

Reactive disulfide bonds in immunoglobulin G. A unique feature in serum proteins of different species.

A reactive disulfide bond (SS)* was detected and characterized in IgG of humans, rats and mice by virtue of disulfide interchange with dithionitrobenzoate. (SS)* was found exclusively in human IgG1 and rat IgG2b. In human IgG1 (SS)* was identified as the upper one of the two interheavy bridges in the hinge, where it appears to take part in complement activation. The biological significance of (SS)* in IgG was underlined by the fact that no other serum proteins were found to exhibit a similar reactivity.

Animals↗
PubMed1996

Characterization of the spontaneous apoptosis of rat thymocytes in vitro.

Unlike splenic or blood lymphocytes, rat thymocytes spontaneously undergo continuously increasing apoptosis during culture. In this study we characterized apoptotic thymus cells of rats according to cell size, nuclear dye binding and surface marker expression. Furthermore, the effects of cell density in culture, the age of the donor animals, glucocorticoids, and inhibition of protein synthesis were studied. It was found that: (1) apoptotic rat thymocytes are recognized in flow cytometry as small, acridine orange low, CD4low, CD8high cells; (2) the rate of apoptosis is dependent on the cell density in the culture in a biphasic manner; (3) thymic apoptosis increases with age of the donor animal in fresh, as well as in 24-hour cultivated cell suspensions; (4) neither adrenalectomy nor in vivo or in vitro treatment with the glucocorticoid antagonist RU 38486 influenced spontaneous apoptosis of thymocytes, and (5) inhibition of protein synthesis, which decreases apoptosis induced by corticosterone, had no effect on spontaneous apoptosis of thymocytes.

Acridine Orange↗
PubMed1995

Serum cytokines in juvenile rheumatoid arthritis. Correlation with conventional inflammation parameters and clinical subtypes.

OBJECTIVE: To examine the usefulness of determining extended serum cytokine profiles in patients with juvenile rheumatoid arthritis (JRA), for the purpose of improving differential diagnosis and monitoring disease activity. METHODS: In a 2-year prospective study, serum levels of interleukin-1 beta (IL-1 beta), soluble IL-2 receptor (sIL-2R), IL-6, IL-8, tumor necrosis factor alpha (TNF alpha), and the p55 soluble TNF receptor (sTNFR) were repeatedly determined by enzyme-linked immunosorbent assay in 40 patients with JRA, 13 patients with postinfectious arthropathies, and 30 healthy controls. The data were compared with conventional parameters of inflammation, such as C-reactive protein (CRP), iron and hemoglobin levels, erythrocyte sedimentation rate (ESR), white blood cell (WBC) counts, and platelet counts. WBC subsets were analyzed by flow cytofluorometry. RESULTS: At the first visit and at the peak of inflammatory activity according to CRP levels and/or ESR, serum levels of sIL-2R, IL-6, and sTNFR in JRA patients correlated significantly with conventional inflammation indicators, whereas IL-1 beta, IL-8, and TNF alpha did not. No changes in leukocyte subset distribution were noted. Among the different clinical subtypes of JRA, sIL-2R, IL-6, and sTNFR values at the time of the initial visit showed a pattern similar to CRP, whereby patients with systemic disease exhibited by far the highest values. TNF alpha and IL-1 beta were variably elevated in certain JRA subtypes. Patients with postinfectious arthropathies showed elevated levels of CRP, sIL-2R, TNF alpha, and sTNFR, which did not differ significantly from levels in the various JRA subtypes with the exception of systemic disease. Detailed analysis of types I and II pauciarticular JRA revealed that levels of CRP, IL-1 beta, and TNF alpha were elevated in patients with type I disease. While these parameters were invariably normal in patients with type II disease, sTNFR and sIL-2R were still found to be significantly elevated. Followup studies suggested that persistently high sTNFR values are a better indicator of JRA activity than are measurements of other cytokines or CRP. CONCLUSION: JRA is associated with significant and consistent changes in serum levels of inflammatory cytokines and soluble receptors. For the clinical monitoring of JRA, determination of levels of sTNFR, and to some extent sIL-2R, may be particularly useful, since these determinations yield information about subtype and/or activity of disease that is not available from conventional parameters of inflammation.

Adolescent↗
PubMed1995

Cholinergic signals to and from the immune system.

This article reviews recent data from our laboratory towards the impact of the autonomous nervous system on mutual interactions between the immune system and the central nervous system. Using a pharmacological approach in rats it is shown that shifts in the adrenergic/cholinergic balance in vivo affect in vitro functions of the non-specific and specific immune system, whereby adrenergic and cholinergic stimulation in general have opposite effects. A high degree of integration appears to exist between cells of the immune system with the cholinergic system. Lymphocytes were found to react to acetylcholine, but are also able to produce and to degradate this neurotransmitter. In addition, changes in the cholinergic tonus were found to affect immune signaling to the brain and to protect thymocytes from apoptosis, possibly via a direct effect on thymic epithelial cells.

Adrenergic Agents↗
PubMed1995

Adrenergic suppression of peripheral blood T cell reactivity in the rat is due to activation of peripheral alpha 2-receptors.

A 20-h treatment of rats with catecholamines using s.c.implantable retard tablets markedly suppresses the in vitro reactivity of peripheral blood (PBL) T lymphocytes, provided that beta-receptors are blocked with propranolol (Felsner et al., 1992). The results can be summarized as follows: (i) the suppressive effect of noradrenaline+propranolol to the concanavalin A (ConA) response of PBL was abolished by the simultaneous application of the alpha-blocker phentolamine. Using selective agonists, the relevant receptor was identified to belong to the alpha 2-subtype. (ii) The alpha-adrenergic suppression of the PBL T cell response was likewise observed in adrenalectomized animals, which rules out the participation of secondarily induced glucocorticoids. Furthermore, the combination of noradrenaline with the watersoluble beta-blocker nadolol was equally effective to suppress the ConA response of PBL. (iii) An analogous alpha-mediated suppression of T cell function of PBL, but not spleen cells, was observed 1 h after i.p. treatment with tyramine, which leads to the release of endogenous noradrenaline. From these results it is concluded that the adrenergic suppression of PBL T cell functions is primarily due to the activation of peripheral alpha 2-receptors and that it is likewise observed under acute indirect sympathomimetic treatment.

Animals↗
PubMed1995

Computer-controlled flushing for long-term cannulation in freely moving rats.

An in vivo long-term perfusion system is presented, which is based on automated, computer-controlled high-frequency heparin (10 U/mL) flushing of the cannula inserted into the tail artery of freely moving rats. The short flushing intervals as achieved with this system guarantee stable conditions throughout an experiment of several days, and reduce blood clotting and the infiltration of fibroblasts. In addition, a specially developed software enables the periodical application of test substances into the blood stream under time-controlled conditions over long periods. The system can be used continuously to follow up blood parameters in single animals without significant elicitation of stress-sensitive plasma catecholamines for up to 12 days.

Animals↗
PubMed1994

Cholinergic stimulation modulates apoptosis and differentiation of murine thymocytes via a nicotinic effect on thymic epithelium.

Effects of cholinergic agonists/antagonists on apoptosis and differentiation of murine thymus cells were investigated in two in vitro models. Treatment with 10(-7) M carbachol was found to counteract the effects of a cortical thymus epithelial cell line (TEC 1.4), on apoptosis and the ratio of CD4 CD8 DP/DN cells in cocultured fetal thymus lobes. A medullary line (TEC 2.3) did not influence apoptosis in fetal thymus lobes. Both TEC lines had the same strong apoptotic effect on thymus cells in suspension, but only the effect of TEC 1.4 was counteracted by carbachol. This cholinergic influence on TEC 1.4 cells is mediated via nicotinic cholinergic receptors, since d-tubocurarine, but not atropine, effectively blocked the effect of carbachol. The results suggest that cholinergic signals to thymic epithelial cells may have regulatory influence on thymic differentiation and selection processes.

Animals↗
PubMed1993

Detection of choline-acetyltransferase activity in lymphocytes.

The cholinergic system takes part in the immune-neuroendocrine integration. Lymphocytes have been found to express muscarinic and nicotinic cholinergic receptors, as well as acetylcholine-esterase on their surface, and cholinergic agents modulate immune functions in vitro and in vivo. In the present study we provide evidence that purified organ resident and circulating lymphocytes, as well as various lymphoid cell lines derived from different species, exhibit choline-acetyltransferase activity and, therefore, have the potential to produce the neurotransmitter acetylcholine.

Animals↗
PubMed1993

Enhancing in vivo effect of propranolol on human lymphocyte function is not due to stereospecific beta-adrenergic blockade.

Immunoenhancing in vivo effects of beta-adrenergic blockers have been previously ascribed to a reduced beta-receptor-mediated immunosuppression. In the present study using a whole blood stimulation assay, the effects of a five-day treatment with the purified (R)- or (S)-isomer of propranolol (3 x 40 mg/day) on the polyclonal in vitro responsiveness of peripheral blood lymphocytes (PBL) of normothyroid and hyperthyroid persons were assessed. It is shown that both isomers likewise exhibit a significant enhancing effect on the proliferative response of PBL to T and B cell mitogens, which strongly argues for nonspecific effects of propranolol to be responsible rather than a specific beta-adrenergic receptor blockade.

Adult↗
PubMed1993

A decrease in reactive disulfide bonds of serum IgG signals a characteristic change in the IgG subclass patterns of rats bearing experimental tumors.

Previous studies have shown that human IgG1 contains a 'reactive' disulfide bridge (SS*), detectable by a 24-hour disulfide exchange reaction, and that the serum level of this IgG subclass is selectively diminished in patients with various malignant diseases. Here we present evidence that in rats IgG2b is the only subclass that carries one SS* per molecule. Furthermore, it is shown that rats inoculated with experimental tumor lines, i.e., the Yoshida hepatoma ascites tumor and the Walker 256 carcinosarcoma growing in ascites or as solid tumor, exhibit significantly decreased SS* per mole IgG which corresponds to a selective diminution of IgG2b. Although at later stages there is a quantitative correlation with the tumor burden, with the Walker tumor this effect becomes significant as early as 24 h after inoculation, i.e., well before exponential tumor growth and an absolute reduction of total IgG. Control animals injected intraperitoneally with either viable spleen cells or irradiated Walker 256 cells did not show comparable alterations in their IgG subclass profile. Thus, the selective defect of IgG2b requires the presence of viable and proliferating tumor cells. Possible mechanism(s) of tumor-associated shifts in IgG subclasses are discussed.

Animals↗