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Biomedical subjects

K Schweizer

Publications and source records attributed to K Schweizer.

At least 19 recordsLinked to original sources
PubMed2002

Encephalitis related to primary varicella-zoster virus infection in immunocompetent children.

INTRODUCTION: Encephalitis is a rare complication of primary varicella-zoster virus (VZV) infection in immunocompetent children. METHODS: The clinical and laboratory findings of two girls with VZV-related encephalitis are reported. RESULTS: Both children presented with focal epileptic seizures, corresponding to cortical/subcortical as well as white matter lesions. The first showed a typical vesicular skin rash. She was easily diagnosed and made a rapid recovery during acyclovir and steroid treatment. In the second girl, a preceding measles-mumps-rubella virus vaccination and the absence of skin vesicles were misleading with respect to the diagnosis, which was finally proven by IgG seroconversion and intrathecal synthesis of IgG antibodies to VZV. She developed left parieto-occipital tissue necrosis and recovered only transiently during initial acyclovir/steroid treatment. Eight weeks after onset, progressive white matter demyelination and the occurrence of erythema nodosum in the lower limbs necessitated a second 4-month course of oral steroids. The VZV PCR from cerebrospinal fluid was negative in both children. CONCLUSIONS: Primary VZV infection may cause severe encephalitis that may occur without skin vesicles and lead to a chronic course with systemic vasculitis. The coincidence of vaccination and neurologic diseases offers no proof per se of a causal relationship.

Acyclovir↗
PubMed2002

Peripheral decrease and pulmonary homing of CD4+CD45RO+ helper memory T cells in cystic fibrosis.

Interstitial lung disease, although of prognostic impact for patients with cystic fibrosis (CF), remains difficult to assess without histopathologic investigations. As changes of peripheral blood lymphocyte subsets (LS) may accompany severe systemic lymphocyte immune responses, we compared peripheral LS of 44 patients with CF, 23 non-CF patients with recurrent pulmonary infections and 83 healthy controls (flow cytometry; CD3, CD19, CD16, CD56, CD4, CD8, CD11b, CD45RA, CD45RO, HLA-DR and CD25 antigens). Additional immunohistochemistry was performed on lung tissue of four CF patients aged 0.5, 12, 17 and 20 years, respectively. Patients with CF showed low absolute counts of CD4+CD45RO+ memory helperT cells, CD16+CD56+ NK cells, CD8+ and interleukin-2 receptor-positive T cells in peripheral blood (P < 0.001). Similar changes were registered in the non-CF patients with pulmonary infections, indicating that those were not specific for CF. Immunohistochemistry showed activation of bronchus-associated lymphoid tissue with interstitial accumulation of CD4+CD45 RO+ T cells in the three older patients. Patients with CF show marked changes of peripheral blood LS which are presumably not CF-specific and may mirror homing to lung tissue in the course of interstitial lung disease. Further research should evaluate its usefulness in monitoring progression of lung disease in CF.

Adolescent↗
PubMed2001

The contributions of memory and attention processes to cognitive abilities.

In two experiments, the contributions of memory and attention processes to the cognitive abilities of reasoning and perceptual speed were investigated. Two measures of speed of information retrieval from long-term and short-term memory (Posner paradigm, Sternberg paradigm) and two attention measures (continuous attention test, attention switching test) were included in the first experiment (N = 220). The memory tests led to correlations with the measures of cognitive abilities, whereas the attention test did not. The same tests as well as one additional memory test and one attention test (working memory test, test of covert orientation) were administered in the second experiment (N = 116). Again, the memory tests led to the larger correlations with the measures of cognitive abilities. Two components were obtained in components analysis, of which the first was characterized by high loadings of the memory tests and the second by high loadings of the attention tests. Only the memory component contributed to the prediction of cognitive abilities.

Adolescent↗
PubMed2001

Effects of gallium and mercury ions on transport systems.

Mercury was previously shown to exert toxic effects by influencing ion channels and transporters in the kidney and brain. Gallium alloys were suggested as less toxic restorative materials. To compare the toxicity of gallium ions with those of mercury ions, we applied gallium nitrate Ga(NO3)3 (0.1-100 microM and mercuric chloride (HgCl2) (0.001-10 microM) to Xenopus oocytes expressing mammalian ion channels and transport proteins. Mercury (10 microM) inhibited the K+-channels ROMK and HERG, the phosphate transporter NaPi-3, the amino acid transporter rBAT, the cation transporter OCT-2, and the osmolyte transporter BGT. It activated the I(Ks)-channel but did not affect the Na+-channel ENaC, the anion channel NaPi-1, and the glucose transporter SGLT-1. Gallium was without significant effect on the channels and on SGLT1, NaPi-3, and rBAT, but inhibited BGT and OCT-2. In conclusion, both Hg2+ and Ga3+ may exert toxic effects on transport systems, which may partially explain their cytotoxic effects.

Amino Acid Transport Systems↗
PubMed2001

[Capacity limitation and intellectual ability].

In a study examining the influence of cognitive capacity limitation on intellectual ability, 124 university students were subjected to 7 computer-based tests in which cognitive demands were manipulated by varying the number of required ordering, arithmetic, and memory operations, respectively. Intelligence data were obtained by forming a composite score from Raven's Advanced Progressive Matrices and the Berlin Intelligence Structure Test. Increases in cognitive demands led to increases in reaction times and number of errors as well as to increases in common variance and in correlations between intelligence and number of errors in 5 and 2 (of 5) comparisons, respectively, while correlations between intelligence and reaction time were found to decrease with increasing task demands in 3 comparisons. All correlations were reduced considerably when storage capacity and coordination efficiency were partialled out. These findings suggest a relationship between capacity limitation and intellectual ability.

Adolescent↗
PubMed2000

Experiences and expectations in evaluating preparation for an examination.

The predictability of the evaluation of preparing for an oral examination by means of self-concept and self-esteem as well as optimism and self-efficacy was investigated in a sample of 49 university students. Self-concept was measured by Frankfurter Selbstkonzeptskalen, self-esteem by the 16PF-O scale, personal optimism, social optimism, and self-efficacy by Fragebogen für Personalen Optimismus und Sozialen Optimismus--Erweitert, and the evaluation of the preparation by a self-report sheet. Data were collected 5 wk. before the examination. The self-report sheet was given again one week before the examination. Significant correlations of self-report scores with self-concept scores as well as 16PF-O scores representing past experiences were found for the first assessment. The correlations with personal optimism scores and self-efficacy scores representing expectations were also significant for the second assessment.

Achievement↗
PubMed2000

[Effects of knowledge acquisition on verbal linearization about spatial orientation].

This paper deals with determinants of linearization in spatial communication. The well-known linearization principles, such as the principle of natural order, primarily emphasize features of the given information. We assume that verbal linearization is in addition influenced by the speakers' knowledge acquisition. Six experiments with a total of 272 participants are reported here. A particular spatial constellation was presented to the participants, who were asked to talk about it afterwards. The linearizations then produced were defined as dependent variables. The results show that the linearizations were influenced by the speaker's experience with the configuration (according-to-experience effect) and also demonstrate the importance of the first encounter (anchor effect). Further characteristics of the effects mentioned above are described and discussed regarding memory research and psycho-linguistics.

Adult↗
PubMed1999

Cognitive bias of optimism and its influence on psychological well-being.

An investigation of the cognitive bias observed in optimism and the influence of optimism on psychological well-being was conducted. The cognitive bias was assumed to be related to the repressive style of information processing, represented by the trait scale of the State-Trait Anxiety Inventory and the Social Desirability scale. Optimism and well-being were measured by the Life Orientation Test and the Social Optimism scale as well as by the Life Satisfaction and Depression scales, respectively. These scales were applied to a sample of 200 individuals. Trait Anxiety and Social Desirability led to a high multiple correlation with the Life Orientation Test (R = .54) and a moderate multiple correlation with the Social Optimism scale (R = .30). Higher correlations were obtained for the expectation of a positive than of a negative future. Both the Life Orientation Test and the Social Optimism scale contributed to the high multiple correlation with psychological well-being (R = .52).

Adult↗
PubMed1998

Effects of a phytopreparation from Helleborus niger on immunocompetent cells in vitro.

Extracts of Helleborus species are used as phytopreparations with immunostimulatory properties in Romanian traditional medicine. In Germany, Helleborus niger is used in homeopathy and as an adjuvant therapy in the treatment of tumor patients in anthroposophical medicine. In vitro application of an aqueous extract from Helleborus niger resulted in a slight induction of sister chromatid exchanges (SCE) in cultured peripheral blood mononuclear cells (PBMC) from healthy individuals, an effect associated with a slight increase of the [3H]thymidine uptake in the DNA of isolated lymphocytes. Since the cytokines interleukin (IL)-2 and tumor necrosis factor (TNF)-alpha were reported to increase the number of SCE, we measured the concentrations of these cytokines in the supernatants of cultured PBMC treated with the plant extract. Here, no significant changes were observed as compared with the controls, but a trend to higher supernatant concentrations of TNF-alpha in six out of ten individuals was noted. Compared with lymphocytes treated with the alkylating substance, cyclophosphamide, the increase of the SCE levels induced by the plant extract is weak. The relevance of this DNA destabilizing property remains to be clarified.

Cell Division↗
PubMed1998

Visual search, reaction time, and cognitive ability.

The contributions of visual search to reaction time and cognitive ability were investigated with 45 subjects. Visual search was assessed via eye movements. The electrooculogram was recorded while a subject located letters arranged in a large display. Reaction time was obtained for a search task. A reasoning and a space scale served to assess cognitive ability. Substantial correlations of number, amplitude, and velocity of saccades with reaction time were obtained. Significant correlations of scores on ability scales with reaction times and amplitudes of saccades were also observed. Obviously, subjects of higher ability showed amplitudes better adjusted to the distances between the letters than those of lower ability.

Adult↗
PubMed1997

Differences in the apoptosis-inducing properties of Viscum album L. extracts.

Viscum album L. (mistletoe) extracts are widely used in adjuvant cancer therapy. In contrast to purified components, such as mistletoe lectins and viscotoxins, whole plant extracts of mistletoe resulted in DNA stabilizations in cyclophosphamide-treated lymphocytes but also provided cytotoxicity in tumour cells and lymphocytes. The killing capacities of mistletoe extracts were host tree-specific and not correlated with mistletoe lectin or viscotoxin content. In human lymphocytes, only mistletoe lectins induced a pathway of apoptotic killing. Within 72 h, the lectin B chains also increased the number of lymphocytes undergoing apoptosis. This finding suggests that inhibition of protein synthesis by the A chain of the hololectin may accelerate a receptor-mediated killing pathway induced by the B chains. An unexpected finding was related to the mistletoe-mediated killing, which was more effective against CD8+T cells with an activated phenotype than CD19+ B cells and CD4+ T cells. In vitro treatment of human neutrophils with mistletoe resulted in a slight decrease of phagocytosis and burst activity. The observed dose-dependent occurrence of two neutrophil subsets with different burst activities indicates differences in their susceptibility to mistletoe and suggests the implication of an induction of the apoptotic killing pathway.

Animals↗
PubMed1996

Induction of apoptosis in human lymphocytes treated with Viscum album L. is mediated by the mistletoe lectins.

Viscum album L. (VAL) is a phytopreparation used in adjuvant cancer therapy with both immunostimulatory and DNA stabilizing properties at low drug concentrations and cytostatic/cytotoxic properties at higher concentrations. The present work examines the cytotoxic effects of VAL extracts produced from mistletoes grown on different host trees and of purified toxic proteins from VAL, such as the D-galactose-specific lectin I (ML I), the N-acetyl-D-galactosamine-specific ML II and ML III, and crude viscotoxins towards cultured human lymphocytes. The decrease in the number of cultured lymphocytes and blast cells treated with whole plant extracts from VAL was host tree-specific. Nevertheless, there was no close correlation to the content of MLs or viscotoxins. Using the purified proteins, it became obvious that the cell killing was mediated by the induction of apoptosis, as measured by the appearance of a hypodiploid DNA peak using flow cytometry. ML III was the most effective to induce apoptosis, followed by ML II and ML I, while the viscotoxins and oligosaccharides from VAL did not. By measuring the surface expression of IL-2R alpha chains, transferrin receptors and APO-1/Fas molecules on non-apoptotic T cells, no significant changes were observed at low ML concentrations (1 ng/ml), but their decrease at higher ones. Our findings suggest that there might be at least two different ways of cell killing operative in VAL-mediated cytotoxicity: (a) the typical apoptotic cell death with the appearance of hypo-diploid nuclei, and (b) a direct or indirect killing by damaging the cell membrane with subsequent influx of Ca2+ and of the DNA intercalating dye propidium iodide and cell shrinkage. These effects might not be exclusive, as they probably occur simultaneously.

Apoptosis↗
PubMed1996

Oculo-bulbar myasthenia gravis induced by cytokine treatment of a patient with metastasized renal cell carcinoma.

OBJECTIVE: The occurrence of autoimmune diseases or deterioration of pre-existing disorders has recently been described after cytokine treatment. The present report gives evidence for acquired myasthenia gravis induced by externally administered interferon-alpha and interleukin-2 in a patient with metastasized renal cell carcinoma. Electromyographic investigations did not reveal generalised myasthenia gravis. However, a highly elevated titre of antibodies against the human acetylcholine receptor and a significant improvement in clinical symptoms during therapy with anticholinesterase drugs, combined with a decremental response in electronystagmography, indicated an intermittent mainly oculo-bulbar form of myasthenia gravis.

Carcinoma, Renal Cell↗
PubMed1995

Effects of Viscum album L. on cyclophosphamide-treated peripheral blood mononuclear cells in vitro: sister chromatid exchanges and activation/proliferation marker expression.

Based on recently published data, Viscum album L. (VAL) extracts have been shown to provide a DNA stabilizing effect which seems to be restricted to the peripheral blood mononuclear cells (PBMC). We have now investigated whether VAL exerts effects of cellular protection for phytohemagglutinin-activated PBMC treated with cyclophosphamdie (CP) in vitro. The addition of VAL resulted in a slight reduction of CP-induced sister chromatid exchanges of cultured PBMC from healthy individuals. The incubation with CP significantly reduced the expression of the low affinity interleukin-2 receptor (IL-2R alpha chain) and of transferrin receptor (TfR) on PHA-stimulated T lymphocytes. The addition of 10 micrograms/ml VAL was protective against the CP-induced depression of IL-2R alpha chain and TfR expression on these cells. The simultaneous addition of CP and purified VAL components, such as ML I, ML II/III, and viscotoxins did not significantly change expression of IL-2R alpha chain and TfR on T cells. Thus, so far undefined VAL components might be responsible for the observed protection effects of the whole plant extract. The results presented here should encourage investigation of this drug, which might become an interesting adjuvant in cancer therapy.

Adult↗
PubMed1995

Sister chromatid exchange-inducing DNA lesions and depression of activation markers on the surface of cultured peripheral blood mononuclear cells after the addition of streptococcal pyrogenic exotoxins A and C.

Cultivation of peripheral blood mononuclear cells (PBMC) in the presence of streptococcal pyrogenic exotoxins (SPE) A and C resulted in a significant induction of sister chromatid exchange (SCE)-inducing DNA lesions. Concomitantly, the expression of interleukin-2 receptor alpha chain (IL-2R alpha chain), transferrin receptor (TfR), and major histocompatibility complex class II molecule HLA-DR on the surface of phytohemagglutinin-activated T cells from whole blood culture cells (WBCC) significantly decreased within 72 h, that is at least two cell cycles, whereas unstimulated T cells from WBCC did not express these markers but had lost their CD3 molecules, an effect reported to precede apoptosis as part of a T cell inactivation pathway. However, no apoptotic cells were observed within a cultivation period of 120 h. We observed clearcut differences in the responses towards SPE A in WBCC and isolated lymphocytes, since SPE A-treated lymphocytes showed an increase in the [3H]thymidine incorporation and did express IL-2R alpha chain and TfR on their cell surface. Regardless of the precise underlying mechanism, T cells from WBCC seem to be in a state of functional incompetence. The data presented here are the first to provide strong evidence that streptococcal toxins produce SCE-inducing DNA lesions in PBMC, an effect that might contribute to the process of immune cell lethality in streptococcal toxic shock-like syndrome and could be of pivotal importance in the pathogenesis of severe streptococcal disease.

Adult↗
PubMed1995

Effect of task demand and stimulus relevance on preattentive processing.

Evidence of cognitively controlled processes influencing preattentive processes is provided. In the first experiment, preattentive processing associated with a discrimination task was compared with that associated with a reaction task. An increase in processing time due to preattentive processes was only found for the discrimination task. In the second experiment, the effects of different amounts of stimulus relevance on preattentive processing were investigated. Stimulus relevance was varied by changing the spatial and temporal distance in cognitively controlled processing. The relevance of the stimulus was proportional to the amount of preattentive processing. It was concluded that the influence of cognitively controlled processing on preattentive processing is moderated by task demand and stimulus relevance. These results are based on observations concerning processing time.

Adult↗
PubMed1995

Effect of Viscum album L. on rapidly proliferating amniotic fluid cells. Sister chromatid exchange frequency and proliferation index.

Amniotic fluid cells (AFC) from 10 women undergoing amniocentesis were investigated. The 5-bromo-2'-deoxyuridine-induced sister chromatid exchange (SCE) frequency of AFC remained stable after the addition of a therapeutical concentration of Viscum album L. preparation Iscador P but decreased significantly after administration of high drug doses. As the proliferation index remained stable, even at extremely high drug concentrations, this effect could not be ascribed to a reduction of proliferation. No indications of cytogenetic damage or effects of mutagenicity were seen after the addition of Viscum album L. preparation P.

Amniotic Fluid↗