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Biomedical subjects

S Koch

Publications and source records attributed to S Koch.

At least 37 records · Page 2Linked to original sources
PubMed2004

Asymptomatic atopy is associated with increased indoleamine 2,3-dioxygenase activity and interleukin-10 production during seasonal allergen exposure.

BACKGROUND: Indoleamine 2,3-dioxygenase (IDO) is a tryptophan (TRP)-catabolizing enzyme with regulatory effects on T cells. T cell inhibition is achieved through both TRP depletion and TRP metabolite accumulation in specific local tissue microenvironments. The expression of IDO activity by different types of antigen-presenting cells (APCs) has been shown to play a role in many instances of immunoregulation and tolerance induction. Induction of IDO after the engagement of the high-affinity receptor for IgE, FcepsilonRI, on atopic monocytes has been suggested to regulate T cell responses in atopic disorders. Interleukin-10 (IL-10), a cytokine known for its down-regulatory functions in the immune system, has recently been associated with the stable expression of IDO in mature tolerogenic dendritic cells. OBJECTIVE: This study was devised to understand the role of systemic IDO and IL-10 in the prevention of clinical apparent allergy. METHODS: The concentration of TRP and the break-down product kynurenine were measured by high-performance liquid chromatography in- and off-season in sera from patients with seasonal allergic rhinitis (n=12) and from clinically asymptomatic atopic patients sensitized to specific aeroallergens (n=12). Non-atopic (NA) individuals (n=12) served as control. The concentration of plasma IL-10 was determined in parallel from these donors by ELISA in- and off-season. RESULTS: In clinically unresponsive but aeroallergen-sensitized atopic individuals significantly higher systemic activity of IDO and increased plasma IL-10 levels were found during allergen exposure but not off-season compared to symptomatic atopic individuals with allergic rhinitis and NA individuals. CONCLUSION: Enhanced systemic IDO activity as well as increased systemic levels of IL-10 may contribute to the containment of allergic T cell responses and could be involved in the maintenance of a state of clinical unresponsiveness.

Adult↗
PubMed2004

Comparative immunophenotyping of monocytes from symptomatic and asymptomatic atopic individuals.

BACKGROUND: Allergy has at least two components - a genetic predisposition referred to as atopy and the progress from an atopic state to clinically apparent disease. Peripheral blood monocytes are circulating myeloid precursors of antigen-presenting cells. The expression of cell surface proteins on monocytes may therefore witness the disease status and affect the development of allergic disease. METHODS: Monocytes were isolated from atopic individuals with seasonal allergic rhinitis (n = 10), from atopic individuals sensitized to aeroallergens but without any signs of acute disease (n = 11), and from healthy nonatopic donors (n = 21). Detailed comparative phenotypic analysis of CD14(+) and FcepsilonRI(+)CD14(+) monocytes was performed by flow cytometry. RESULTS: CD14(+) monocytes from symptomatic atopic donors showed a significant increase in the cell surface intensity of the integrin adhesion molecule CD11c over monocytes from asymptomatic atopic and nonatopic donors. Asymptomatic atopic individuals showed significantly enhanced expression of FcepsilonRI on the CD14(high)CD16(dim) monocyte subset compared with this subset from symptomatic atopic and nonatopic donors. CONCLUSION: The increase in monocyte surface intensity of the adhesion molecule CD11c may be involved in the manifestation of allergic disease. FcepsilonRI on CD14(high)CD16(dim) monocytes of asymptomatic atopic donors may be of functional importance for the maintenance of clinical unresponsiveness toward allergens.

Adult↗
PubMed2004

Lethal otogenic Candida meningitis.

History revealed a chronic obstructive pulmonary condition which had been treated with prednisolone for a long time. There was a raised temperature with further signs of an acute inflammatory underlying disease and internal hydrocephalus. After performing trepanation, the symptoms of raised intercerebral pressure ceased. Candida albicans could be detected microbiologically in the cerebrospinal fluid. There was no pneumonia at the time of admission. Despite instituting immediate intensive care with administration of antibiotics and antimycotics, the patient died 11 days after inpatient admission. Autopsy revealed a C. albicans mycosis originating from the right middle ear with extensive suppurative meningitis, which was the immediate cause of death. Confluent bronchopneumonia had developed in both lower lung lobes at the time of death, but did not show any signs of mycosis and had contributed indirectly to the death of the patient.

Autopsy↗
PubMed2004

[Lepirudin for therapeutic use in heparin-induced thrombocytopenia].

Heparin-induced thrombocytopenia (HIT) type II is an antibody mediated severe adverse event to heparin with a paradoxical decrease of platelet count and an increased risk for thromboembolic complications. The antibodies are directed against a neoepitop of platelet factor 4 after its binding to heparin. The incidence of HIT type II is lower with low-molecular-weight heparin compared to unfractionated heparin and lower in not operated patients compared to those after major surgery. In patients with HIT type II alternative anticoagulation has to be performed immediately due to the high thrombogenicity of the antibodies. The recombinant hirudin lepirudin (Refludan) is the anticoagulant drug of choice. A long-term anticoagulation has to be performed depending on the concomitant risk factors, intravenous administration followed by subcutaneous lepirudin overlapping with vitamin K antagonists.

Anticoagulants↗
PubMed2003

Diagnostic value of sural nerve matrix metalloproteinase-9 in diabetic patients with CIDP.

Patients with diabetes mellitus (DM) may develop chronic inflammatory demyelinating polyneuropathy (CIDP), which may be difficult to distinguish from diabetic neuropathy (DNP). Here the authors show that immunoreactivity for matrix metalloproteinase-9 on sural nerve biopsies may help to identify CIDP-DM. In a pilot study on 10 CIDP-DM patients with IV immunoglobulins and tight glycemic control, the CIDP-DM patients had a better outcome than DNP patients treated with tight glycemic control only.

Adult↗
PubMed2003

Efficacy of cytotoxic agents used in the treatment of testicular germ cell tumours under normoxic and hypoxic conditions in vitro.

Platinum-based chemotherapy is the main treatment element to achieve cure for patients with metastatic germ cell tumours. Drug resistance in testicular germ cell tumours (TGCTs) is rare and the reasons are not fully understood. While recent investigations have indicated decreased efficacy of chemotherapy in several tumour types under hypoxic conditions, this aspect has not been investigated in TGCTs so far. Furthermore, for cisplatin - the most active drug in this disease - controversial effects of hypoxia on cytotoxic efficacy have been reported. The relative efficacy of cytotoxic agents for the treatment of TGCT patients was studied in three different cell lines derived from human embryonal carcinomas (EC) in an in vitro hypoxia model. NT2, 2102 EP, and NCCIT were tested for their sensitivity towards cisplatin, etoposide, bleomycin, 4-OOH-ifosfamide, carboplatin, paclitaxel, gemcitabine, oxaliplatin, irinotecan, and mitomycin C under normoxic and hypoxic conditions using the MTT assay. Inhibitory concentrations IC(50) of the tested agents under both conditions were compared. Selected results were confirmed by flow-cytometric assessment of the apoptotic index. In all cells, doubling times were prolonged in hypoxia (NT2<NCCIT<2102 EP). All drugs were less effective under hypoxic conditions, including mitomycin C (eg, 1.6-fold increase of IC(50) in hypoxia compared to normoxia for NT2) and cisplatin (eg, NT2: two-fold increase). The relative effect of hypoxia on the IC(50) depended mainly on the cell line, and to a lesser extent on the drug. The results indicate that the reduced cell proliferation in hypoxia might be an important factor, but not the only determinant of a reduced cytotoxicity. In view of the broad spectrum of drugs with different modes of action tested, the relative resistance cannot be mediated by substance-specific resistance mechanisms like hypoxia-induced upregulation of P-glycoprotein or increased DNA-repair capacity, since many unrelated drugs were affected to a comparable extent in their efficacy by hypoxia. This study also provides the rationale to test the hypothesis whether improving tumour oxygenation by raising haemoglobin concentrations, for example, with erythropoietin in patients with TGCTs receiving chemotherapy may improve the outcome.

Antineoplastic Agents↗
PubMed2003

[Hygienic requirements for biopsy and autopsy diagnostics].

In former times autopsies were the main task of a pathologist and therefore the most frequent source of infection but nowadays cytological and biopsy investigations dominate the pathologist's work. Usually the time interval between the extraction of a specimen, its transport into the laboratory and return of the report is no longer than a few hours. Consequently the staff must often handle unfixed or insufficiently fixed material. This and the occurrence of new infectious diseases, e.g. AIDS and TSE (transmissible spongiform encephalopathies), makes it necessary to analyse and perhaps even change the work in respect to hygiene risks and demands for permanent protection against infection. First of all the risks of infection and the common measures of protection from infections for the staff in biopsy and autopsy departments will be described. Subsequently suggestions to reduce infectious risks in special activities will be presented. The examination of frozen sections or intraoperative biopsy material and the handling of specimens possibly contaminated by HIV and TSE will be considered separately.

Autopsy↗
PubMed2003

Refinement of the nickel site structure in Desulfovibrio gigas hydrogenase using range-extended EXAFS spectroscopy.

We have reexamined the Ni EXAFS of oxidized, inactive (as-isolated) and H(2) reduced Desulfovibrio gigas hydrogenase. Better spatial resolution was achieved by analyzing the data over a 50% wider k-range than was previously available. A lower k(min) was obtained using the FEFF code for phase shifts and amplitudes. A higher k(max) was obtained by removing an interfering Cu signal from the raw spectra using multiple energy fluorescence detection. The larger k-range allowed us to better resolve the Ni-S bond lengths and to define more accurately the Ni-O and Ni-Fe bond lengths. We find that as-isolated, hydrogenase has two Ni-S bonds at approximately 2.2 A, but also 1-2 Ni-S bonds in the 2.35+/-0.05 A range. A Ni-O interaction is evident at 1.91 A. The as-isolated Ni-Fe distance cannot be unambiguously determined. Upon H(2) reduction, two short Ni-S bonds persist at approximately 2.2 A, but the remaining Ni-S bonds lengthen to 2.47+/-0.05 A. Good simulations are obtained with a Ni-Fe distance at 2.52 A, in agreement with crystal structures of the reduced enzyme. Although not evident in the crystal structures, an improvement in the fit is obtained by inclusion of one Ni-O interaction at 2.03 A. Implications of these distances for the spin-state of H(2) reduced H(2)ase are discussed.

Absorption↗
PubMed2003

Intracerebral alveolar echinococcosis.

There are two species of the genus Echinococcus, Echinococcus multilocularis (also called alveolar hydatid) and Echinococcus granulosus, characterized by distinct growth features in humans. The main endemic regions for human alveolar echinococcosis (AE) caused by E. multilocularis are Central Europe, Russia, Turkey, Japan, China, eastern France and North America. Human echinococcosis is usually caused by an intrahepatic growth of parasitic larvae. Cerebral occurrence of E. multilocularis disease is rare, accounting for only 1% of cases, and is generally considered to be fatal. This report presents two cases of intracerebral E. multilocularis disease which occurred in two infected patients with AE pulmonary metastases. The anatomical and clinical features are discussed. Our retrospective survey would indicate that surgical treatment should be envisaged whenever possible.

Adult↗
PubMed2003

Designing clinically useful systems: examples from medicine and dentistry.

Despite promising results in medical informatics research and the development of a large number of different systems, few systems get beyond a prototype state and are really used in practice. Among other factors, the lack of explicit user focus is one main reason. The research projects presented in this paper follow a user-centered system development approach based on extensive work analyses in interdisciplinary working groups, taking into account human cognitive performance. Different medical and health-care specialists, together with researchers in human-computer interaction and medical informatics, specify future clinical work scenarios. Special focus is put on analysis and design of the information and communication flow and on exploration of intuitive visualization and interaction techniques for clinical information. Adequate choice of the technical access device is made depending on the user's work situation. It is the purpose of this paper to apply this method in two different research projects and thereby to show its potential for designing clinically useful systems that do support and not hamper clinical work. These research projects cover IT support for chairside work in dentistry (http://www.dis.uu.se/mdi/research/projects/orquest) and ICT support for home health care of elderly citizens (http://www.medsci.uu.se/mie/project/closecare).

Aged↗
PubMed2002

Absence of c-KIT and members of the epidermal growth factor receptor family in refractory germ cell cancer.

BACKGROUND: Germ cell tumors (GCTs) in adolescent and young males are very sensitive to cisplatin-based chemotherapy. However, 10-20% of the patients cannot be cured by currently available therapeutic options. Once a tumor does not respond to cisplatin, current therapeutic modalities offer only a chance for short palliation. Recently, new treatment options that interfere with various receptor tyrosine kinases, including c-KIT and members of the epidermal growth factor receptor (EGFR) family, have been used successfully in chemotherapy-resistant tumors overexpressing c-KIT, ERB-B2, or EGFR. METHODS: We studied the presence of c-KIT and the four members of the EGFR family by immunohistochemistry, as well as by ERB-B2 gene amplification using fluorescent in situ hybridization, in a series of 22 patients with cisplatin-resistant GCTs in search of new treatment targets. The results in these refractory tumors were compared with those of 12 patients with chemosensitive GCTs diagnosed in an advanced metastatic stage. RESULTS: The data obtained in both groups did not differ in any of the investigated biologic markers. c-KIT was detected in the one case of pure seminoma studied and in the seminomatous components of combined tumors. The presence of EGFR was restricted to trophoblastic giant cells and the syncytiotrophoblastic elements of four nonseminomas including one pure choriocarcinoma and to a secondary non-germ cell malignancy, which had developed most likely from a mature teratoma. ERB-B2 was moderately positive in the secondary non-germ cell malignancy, in one mature teratoma component of a mixed nonseminoma, and together with EGFR in the syncytiotrophoblastic cells of a pure choriocarcinoma. Of all samples investigated, this latter case was the only one showing an amplification of the ERB-B2 gene in the syncytiotrophoblasts. ERB-B3 and ERB-B4 were detected rarely. CONCLUSION: The majority of refractory GCTs do not qualify for treatment with new biologic agents targeting the receptor tyrosine kinases EGFR, ERB-B2, or c-KIT. The lack of differences between the tumors of refractory and the responsive patients indicates that overexpression of any of these receptor tyrosine kinases does not contribute to a resistant phenotype in GCTs.

Adolescent↗
PubMed2002

Antigen-presenting cells and tolerance induction.

T cell tolerance induction to foreign and self-antigens has occupied research since the beginning of the understanding of the immune system. Much controversy still exists on this question even though new methods became available to investigate immunoregulatory mechanisms. Antigen-presenting cells play a pivotal role in transferring information from the periphery of the organism to lymphoid organs. There, they initiate not only the activation of naive T cells but seem to deliver important signals which result in T cell unresponsiveness with antigen-specific tolerance induction.

Animals↗
PubMed2001

B cell immunodeficiency fails to develop in CD4-deficient mice infected with BM5: murine AIDS as a multistep disease.

The immunodeficiency syndrome murine AIDS (MAIDS), caused by the BM5 retrovirus preparation, involves the activation, division, and subsequent anergy of the entire CD4(+) T cell population as well as extensive B cell hyperproliferation and hypergammaglobulinemia, resulting in splenomegaly and lymphadenopathy, followed many weeks later by death. The development of MAIDS requires CD4(+) T cells and MHC class II expression by the infected host, supporting a role for T-B interaction in disease development or progression. To explore this possibility, we examined development of MAIDS in mice deficient in CD4 (CD4 knockout), in which T-B interactions are compromised. We find that in CD4 knockout hosts, BM5 causes T cell immunodeficiency in the remaining T cells but has only a limited ability to induce B cell phenotypic changes, hyperproliferation, hypergammaglobulinemia, or splenomegaly. There is also delayed death of infected mice. This implies that CD4 dependent T-B interaction is needed to induce the B cell aspects of disease and supports a multistep mechanism of disease in which B cell changes follow and are caused by CD4(+) T cell effects.

Animals↗
PubMed2001

Functional disorders of the sympathetic nervous system in mice lacking the alpha 1B subunit (Cav 2.2) of N-type calcium channels.

N-type voltage-dependent Ca(2+) channels (VDCCs), predominantly localized in the nervous system, have been considered to play an essential role in a variety of neuronal functions, including neurotransmitter release at sympathetic nerve terminals. As a direct approach to elucidating the physiological significance of N-type VDCCs, we have generated mice genetically deficient in the alpha(1B) subunit (Ca(v) 2.2). The alpha(1B)-deficient null mice, surprisingly, have a normal life span and are free from apparent behavioral defects. A complete and selective elimination of N-type currents, sensitive to omega-conotoxin GVIA, was observed without significant changes in the activity of other VDCC types in neuronal preparations of mutant mice. The baroreflex response, mediated by the sympathetic nervous system, was markedly reduced after bilateral carotid occlusion. In isolated left atria prepared from N-type-deficient mice, the positive inotropic responses to electrical sympathetic neuronal stimulation were dramatically decreased compared with those of normal mice. In contrast, parasympathetic nervous activity in the mutant mice was nearly identical to that of wild-type mice. Interestingly, the mutant mice showed sustained elevation of heart rate and blood pressure. These results provide direct evidence that N-type VDCCs are indispensable for the function of the sympathetic nervous system in circulatory regulation and indicate that N-type VDCC-deficient mice will be a useful model for studying disorders attributable to sympathetic nerve dysfunction.

Animals↗
PubMed2001

Prospective, randomized, sequential, crossover trial of large-volume vs. normal-volume leukapheresis procedures: effects on subpopulations of CD34(+) cells.

Some data exist on the influence of leukapheresis volume on the number of harvested peripheral blood hematopoietic progenitor cells (HPC), but less is known about the influence on the composition of HPC. We therefore performed a prospective, randomized crossover trial to evaluate the effect of large-volume (LVL) vs. normal-volume leukapheresis (NVL) on subpopulations of CD34(+) cells in the harvest product of 15 patients with breast cancer and 8 patients with non-Hodgkin's lymphoma. Patients were randomly assigned to start either with an LVL on day 1 followed by an NVL on day 2 or vice versa. The number of HPC, the extraction efficiency defined as difference between yield in the harvest and decrease in peripheral blood, and the relative proportion as well as the absolute numbers of CD34(+) cells coexpressing CD38, CD90, HLA-DR, CD117, CD7, CD19, CD41, or CD33 were evaluated. There was no significant difference with regard to the percentages of the subsets on comparison of LVL to NVL procedures. Only the absolute median number of CD34(+)HLA-DR(-) cells was significantly (P=0.02) higher in LVL harvests compared with the corresponding NVL components, which can be explained on the basis of the higher yield and the higher extraction efficiency in LVL compared with NVL. LVL results in a higher yield of CD34(+) cells and leads to an intra-apheresis recruitment of HPC but the relative composition of the harvested CD34(+) cells is not changed significantly. In addition, the amount of early, HLA-DR(-), hematopoietic HPC seems to be increased by an LVL.

Adult↗
PubMed2001

[Socio-familial and epilepsy specific stress on women with epilepsy].

The Berlin longitudinal study on teratogenic effects of maternal epilepsy was conducted on children in 1976. Approximately 18 years later, 103 of these children's mothers were reassessed with regard to somatic, psychological, and social well-being or impairment. The families with previously diagnosed epileptic mothers (n = 59) and control families (n = 44) did not statistically differ in rates of family separation, divorce, or unemployment of the partners. There were also no significant differences in the mothers' current psychological quality-of-life status (SF-36) or their beliefs on internal or external disease control (FKK). There were, however, group differences in more closely illness-related aspects. In spite of an appreciable remission rate of 28% over the past 17 years, significantly more mothers in the epilepsy group still reported physical infirmities (GBB), reduced body-related quality of life (SF-36), and more family stress events (FAI). Their self-esteem and competence-related beliefs (FSKN) were significantly lower. They also tended to have a lower level of education or professional training, and some had never been employed. When measuring quality of life, severity of seizure (NHS3) and early epilepsy onset are the major risk factors, regardless of whether one uses epilepsy-specific (QOLIE-10) or general quality-of-life questionnaires (SF-36).

Abnormalities, Drug-Induced↗
PubMed2001

Pattern of chromosomal imbalances in non-B virus related hepatocellular carcinoma detected by comparative genomic hybridization.

Only limited data are available on comparative genomic hybridization (CGH) in hepatocellular carcinoma (HCC). They concern mainly B virus related HCC. Therefore, we used CGH to detect chromosomal imbalances in 16 non-B virus related HCC in alcoholic cirrhosis in 7 cases (HA1 to HA7), in C virus cirrhosis in 7 cases (HC1 to HC7), in non-cirrhotic liver in 2 cases (NC1, NC2), and in 9 non-malignant cirrhotic tissues. The most frequent imbalances in HCC were gains of whole chromosomes or chromosomal regions 7 or 7q (10/16, 62%), 1q (9/16, 56%), 5 or 5q (9/16, 56%), 8q (8/16, 50%), 6p (6/16, 37%), 15q (5/16, 31%), 20 or 20q (5/16, 31%), and losses of 17p (6/16, 37%), and 8p (5/16, 31%). High-level gains were identified in HCC on 1q (2/16), 3q (1/16), 7q (1/16), and 8q (3/16). No chromosomal imbalances were detected in any of the cirrhotic tissues. Most of the gains, losses, and amplifications detected in this CGH study corresponded well to those identified in previous studies, except for gains of whole chromosome 5 or 7 and/or of chromosome arms 5q or 7q and losses on 4q. Our results suggest that other chromosomal regions are involved in hepatocarcinogenesis.

Carcinoma, Hepatocellular↗