Biomedical subjects

G Köhler

Publications and source records attributed to G Köhler.

At least 55 records · Page 3Linked to original sources

PubMed1999

Proliferation and survival of mammary carcinoma cells are influenced by culture conditions used for ex vivo expansion of CD34(+) blood progenitor cells.

Malignant cell contamination in autologous transplants is a potential origin of tumor relapse. Ex vivo expansion of CD34(+) blood progenitor cells (BPC) has been proposed as a tool to eliminate tumor cells from autografts. To characterize the influence of culture conditions on survival, growth, and clonogenicity of malignant cells, we isolated primary mammary carcinoma cells from pleural effusions and ascites of patients with metastatic breast cancer and cultured them in the presence of stem cell factor (SCF), interleukin-1beta (IL-1beta), IL-3, IL-6, and erythropoietin (EPO), ie, conditions previously shown to allow efficient ex vivo expansion of CD34(+) BPC. In the presence of serum, tumor cells proliferated during a 7-day culture period and no significant growth-modulatory effect was attributable to the presence of hematopoietic growth factors. When transforming growth factor-beta1 (TGF-beta1) was added to these cultures, proliferation of breast cancer cells was reduced. Expansion of clonogenic tumor cells was seen in the presence of SCF + IL-1beta + IL-3 + IL-6 + EPO, but was suppressed by TGF-beta1. Cocultures of tumor cells in direct cellular contact with hematopoietic cells showed that tumor cell growth could be stimulated by ex vivo expanded hematopoietic cells at high cell densities (5 x 10(5)/mL). In contrast, culture under serum-free conditions resulted in death of greater than 90% of breast cancer cells within 7 days and a further decrease in tumor cell numbers thereafter. In the serum-free cultures, hematopoietic cytokines and cellular contact with CD34(+) BPC could not protect the tumor cells from death. Therefore, ex vivo expansion of CD34(+) BPC in serum-free medium provides an environment for efficient purging of contaminating mammary carcinoma cells. These results have clinical significance for future protocols in autologous progenitor cell transplantation in cancer patients.

Antigens, CD34↗

PubMed1999

Sleep and endocrine changes after intranasal administration of growth hormone-releasing hormone in young and aged humans.

Systemic administration of growth hormone-releasing hormone (GHRH) has been found to improve human sleep in previous studies. Here we examined effects of GHRH on endocrine function and sleep after intranasal administration, a method which based on previous studies appears to enable a direct effect of peptides on brain function. Also, it was hypothesized that elderly humans displaying deficient GH release and sleep, benefit from GHRH administration more than young subjects. A study was performed according to a double-blind cross-over design. Each of 12 young and 11 old healthy men were intranasally administered with 300 micrograms GHRH (vs. placebo) 30 min before bedtime at 23:00 h. Sleep was recorded polysomnographically until 07:00 h and blood was collected in 15 min intervals for determination of cortisol and GH. Apart from the well-known age-related changes of hormonal secretion and sleep, intranasal GHRH reduced cortisol nadir concentrations in the beginning of sleep (P < 0.05), and also reduced the sleep-induced elevation in GH concentrations during early sleep. Moreover, results indicated that after intranasal administration GHRH increased rapid-eye-movement (REM) sleep and slow wave sleep (SWS), with this influence concentrating on the second half of sleep time. Effects of GHRH did not depend on the subject's age. We conclude that there is a coordinate influence of intranasal GHRH on the central nervous regulation of sleep processes and of hypothalamic-hypophysiotropic secretory activity in both young and elderly men. The effects may mimic the dual neuronal and endocrine function of hypothalamic GHRH activity.

Administration, Intranasal↗

PubMed1999

Selective assembly of cyclodextrins on poly(ethylene oxide)-poly(propylene oxide) block copolymers.

This paper presents a computational study on the formation of a molecular necklace formed by specific threading of cyclodextrins (CDs) on block copolymers. Structural as well as energetic principles for the selective complexation of alpha- and beta-cyclodextrin with poly(ethylene oxide)-poly(propylene oxide) block copolymers (PEO-PPO) are elucidated considering a diblock copolymer of equimolecular composition (PEO)4-(PPO)4 as guest. A non-statistical distribution of CDs, i.e. alpha-CDs primarily located on the PEO chain and beta-CDs on PPO blocks of the polymer, is based on a variety of structural features and energetic preferences considering both potential as well as solvation energies. This selectivity becomes already obvious considering 1:1 complexes between PEO and PPO monomers and the two CDs, but is increasingly evident when calculating higher order ensembles. Besides the host-guest interaction, docking between CDs themselves is an important, also non-statistical, prerequisite for the self-assembly of highly ordered tubes. The formation of intermolecular hydrogen bonds between adjacent CDs in a tubular aggregate gives an important contribution to the overall stability of the molecular necklace. The net effect, based on the preferential interaction between host and guest as well as between the host molecules themselves, results in the formation of a stable, highly ordered macromolecular, multicomponent aggregate.

Cyclodextrins↗

PubMed1999

Negative regulation of airway responsiveness that is dependent on gammadelta T cells and independent of alphabeta T cells.

The mechanisms regulating airway function are complex and still poorly understood. In diseases such as asthma, involvement of immune-dependent mechanisms has been suggested in causing changes in airway responsiveness to bronchoconstrictors. We now demonstrate that gammadelta T cells can regulate airway function in an alphabeta T cell-independent manner, identifying them as important cells in pulmonary homeostasis. This function of gammadelta T cells differs from previously described immune-dependent mechanisms and may reflect their interaction with innate systems of host defense.

Animals↗

PubMed1999

Host-induced, stage-specific virulence gene activation in Candida albicans during infection.

An understanding of the complex interactions between pathogenic microbes and their host must include the identification of gene expression patterns during infection. To detect the activation of virulence genes in the opportunistic fungal pathogen Candida albicans in vivo by host signals, we devised a reporter system that is based on FLP-mediated genetic recombination. The FLP gene, encoding the site-specific recombinase FLP, was genetically modified for expression in C. albicans and fused to the promoter of the SAP2 gene that codes for one of the secreted aspartic proteinases, which are putative virulence factors of C. albicans. The SAP2P-FLP fusion was integrated into one of the SAP2 alleles in a strain that contained a deletable marker that conferred resistance to mycophenolic acid and was flanked by direct repeats of the FLP recognition target (FRT). Using this reporter system, a transient gene induction could be monitored at the level of single cells by the mycophenolic acid-sensitive phenotype of the colonies generated from such cells after FLP-mediated marker excision. In two mouse models of disseminated candidiasis, SAP2 expression was not observed in the initial phase of infection, but the SAP2 gene was strongly induced after dissemination into deep organs. In contrast, in a mouse model of oesophageal candidiasis in which dissemination into internal organs did not occur, no SAP2 expression was detected at any time. Our results support a role of the SAP2 gene in the late stages of an infection, after fungal spread into deep tissue. This new in vivo expression technology (IVET) for a human fungal pathogen allows the detection of virulence gene induction at different stages of an infection, and therefore provides clues about the role of these genes in the disease process.

Animals↗

PubMed1999

IL-12 is dispensable for innate and adaptive immunity against low doses of Listeria monocytogenes.

We have studied IL-12p35-deficient (IL-12p35(-/-)) mice to evaluate the role of IL-12 in resistance against Listeria monocytogenes. In the absence of bioactive IL-12p75, mutant mice acquired higher bacterial organ burden than wild-type mice and died during the first week following infection with normally sublethal doses of Listeria. Moreover, blood IFN-gamma levels were strikingly reduced in mutant mice at day 2 post-infection. These results suggest that in IL-12p35-deficient mice impaired production of IFN-gamma which is crucial for activation of listericidal effector functions of macrophages leads to defective innate immunity against Listeria. In contrast to mice deficient for IFN-gamma or IFN-gamma receptor which are unable to resist very low infection doses of Listeria, IL-12p35(-/-) mice resisted up to 1000 c.f.u. and were able to eliminate Listeria. Spleen cells from mutant mice re-stimulated with heat-killed Listeria produced considerable amounts of IFN-gamma, suggesting that at low dose infection sufficient IFN-gamma is produced independently of IL-12. Subsequent challenge of these immunized mice with high doses of L. monocytogenes resulted in sterile elimination demonstrating efficient memory responses. These results demonstrate for the first time that at low doses of Listeria IL-12 is neither critical for innate immunity nor for the development of protective T cell-dependent acquired immunity.

Animals↗

PubMed1999

[Adherence and invasion-two pathogenicity factors in bacterial and fungal pathogens].

Pathogenicity factors such as adhesins, toxins, capsules, and other microbial gene products are involved as causative agents for infectious diseases. Therefore, the pathogenicity of organisms is increasingly studied on a molecular level. In bacteriology, unspecific adherence mechanisms and receptor-specific adhesins have to be distinguished. An adhesin-mediated invasion of pathogenic organisms in eukaryotic host cells could be relevant for pathogenesis. In mycology, various specific adhesins are involved in colonization of the host. Aspartyl proteases and phospholipases are relevant for adherence and invasion of host structures by pathogenic yeasts. Resistance factors have a central function in the distribution of infectious organisms. Gene-transfer, point mutations and efflux mechanisms are involved in the development of antibiotic drug resistance. Antifungal drug resistance does occur predominantly in Candida albicans against azole drugs. As underlying mechanisms point mutations in the ERG11 gene, encoding for the target enzyme of azoles, as well as energy-dependent efflux mechanisms were identified. Whether these mycotic factors are specific virulence factors or "fitness-factors" for a better survival of these organisms in the host, and if a possible alternating effect exists between resistance and virulence mechanisms is currently under investigation.

Adhesins, Bacterial↗

PubMed1999

Pro-inflammatory and T cell inhibitory cytokines are secreted at high levels in tumor cell cultures of human renal cell carcinoma.

OBJECTIVES: The objectives of this study were to assess cytokine secretion in human renal cell carcinoma (RCC) and to identify cytokines contributing to the immunomodulatory effect of tumor cells. METHODS: Cytokine secretion in the supernatant of primary tumor cell cultures (PTCC) and corresponding cell lines (CL) was assayed using ELISA. Tumor cells were characterized by morphology, immunocytochemistry, and flow-cytometric analysis. Tumor-cell-induced T cell activation was determined by coculture of gamma delta and alpha beta T cell clones with tumor CL. RESULTS: We assessed the cytokine secretion of tumor cells from 27 PTCC and their corresponding CL (3/27) of RCC. We found that RCC predominantly produced both pro-inflammatory and T-cell-inhibitory cytokines, such as IL-8, IL-6, GM-CSF, TNF-alpha, IL-10 and TGF-beta 1. CL were adapted to serum-free medium which may prove as a useful tool in future studies of cytokine secretion in RCC. In addition, we used gamma delta and alpha beta T cell clones to assess the immunomodulatory effect of tumor cells from RCC and found that predominantly gamma delta T cells were activated by RCC. CONCLUSIONS: Our data suggest that RCC produce large amounts of both pro-inflammatory and T-cell-inhibitory cytokines that potentially could influence the immune response of the host, especially tumor-specific cytotoxic T cells.

Biomarkers, Tumor↗

PubMed1999

Efficacy and safety of a fixed combination phytomedicine in the treatment of the common cold (acute viral respiratory tract infection): results of a randomised, double blind, placebo controlled, multicentre study.

OBJECTIVE: The common cold (acute viral respiratory tract infection) is one of the most frequent diseases in man, world-wide. Clinically relevant efficacy should include early improvement of all symptoms. Results of a clinical trial of a commercially available fixed combination herbal remedy (Radix echinaceae, Radix baptisiae, Herba thujae) are reported here. The aim of this study was to verify clinical efficacy shown in recent studies under (i) good clinical practice (GCP) quality assurance and (ii) common situations at family doctors. METHODS: Patients attending one of 15 study centres (practitioners) as a result of an acute common cold were randomised to the double-blind placebo-controlled study. Three tablets of study medication were applied t.i.d. for 7 to 9 days. Patients daily documented the intensity of 18 cold symptoms, as well as the cold overall, using a 10-point scale and estimated their general well-being using the Welzel-Kohnen colour scales. Additionally, the severity of illness was assessed by the physician on days 4 and 8 (CGI-1). The main and confirmatory outcome measure was expressed as a total efficacy value. This was gauged from the z-standardised AUC values of the primary endpoints (rhinitis score, bronchitis score, CGI-1 and general well-being). Adverse events, overall tolerability, vital signs and laboratory parameters were documented. RESULTS: 263 patients were included. For safety analysis, all patients were used. 259 patients were evaluable for primary efficacy analysis (ITT). Results were confirmed analysing only the 238 valid cases (VCs). The primary efficacy parameters showed the superiority of the herbal remedy over placebo (p < 0.05). Effect size was 20.6% of the standard deviation (90% CI: 0.04-41.1%; ITT) and 23.1% (1.7-44.5%; VC). In relation to the general well-being, the effect size was 33.9% of the standard deviation (12.5-55.3%; VC). Patients who suffered from at least moderate symptom intensity at baseline showed response rates (at least 50% improvement of the global score, day 5) of 55.3% in the herbal remedy group and 27.3% in the placebo group (p = 0.017; NNT = 3.5). In the subgroup of patients who started therapy at an early phase of their cold, the efficacy of the herbal remedy was most prominent (p = 0.014 for the primary efficacy parameter). The therapeutic benefit of the herbal remedy had already occurred on day 2 and reached significance (p < 0.05) on day 4, and continued until the end of the treatment in the totdl score of symptoms, bronchitis score and rhinitis score, as well as in the patients' overall rating of the cold intensity. At that time, equal levels of improvement were reached three days earlier in the verum group than in the placebo group. In 26 patients receiving the herbal remedy and 23 patients receiving placebo, adverse events were reported. Adverse drug reactions were suspected in two patients in the verum group and in four patients in the placebo group. Serious adverse events did not occur. CONCLUSIONS: This study shows that the herbal remedy is effective and safe. The therapeutic benefit consists of a rapid onset of improvement of cold symptoms. If patients with colds are able to start the application of the herbal remedy as soon as practical after the occurrence of the initial symptoms, the benefit would be expected to increase (e.g. self-medication).

Adult↗

PubMed1999

[100 years of the Wertheim operation--Ernst Wertheim between myth and reality].

100 years ago, on November 16, 1898, Ernst Wertheim performed the first radical abdominal hysterectomy for cervical cancer wearing his name. In this historical survey the life story of Wertheim is described involving morally questionable behaviours, misconceptions to radiation therapy, and problems regarding his obstetrical teaching. In context to the Wertheim-operation the vaginal radical hysterectomy developed by Schuchardt and Schauta and the radiation therapy of cervical cancer in the Wertheim-era are discussed.

Ethics, Medical↗

PubMed1999

Sensitization of tumor cells to ribotoxic stress-induced apoptotic cell death: a new therapeutic strategy.

We describe a procedure that sensitizes chemotherapy-and tumor necrosis factor-resistant human tumor cell populations in vitro and in nude mouse transplants to the immediate triggering of high rates of cell death by anisomycin, an agent causing activation of stress-activated protein kinases [SAPKs, as defined by P. Cohen (Trends Cell Biol., 7: 353-361, 1997)] including p38/RK and c-jun NH2-terminal kinase homologues, following its binding to ribosomal 28S RNA (M. S. Iordanov et al, Mol. Cell. Biol., 17: 3373-3381, 1997). Sensitization is effected by successive application of an inhibitor of histone deacetylation (trichostatin A, butyrate) and of flavopiridol, known as an inhibitor of cyclin dependent kinases and evaluated presently in clinical trials. Effective concentrations of anisomycin, flavopiridol, and trichostatin A are in the submicromolar range. Tumor cell death can be prevented by epidermal growth factor (EGF), if added before flavopiridol or after anisomycin but not if applied between the additions of these agents, suggesting that flavopiridol interrupts an EGF-activated survival pathway and that anisomycin, besides triggering cell death, guards this pathway against the interference by flavopiridol. In contrast to EGF, dibutyryl-cAMP exerts protection that is flavopiridol-insensitive. For triggering cell death, anisomycin cannot be replaced by DNA- or mitotic spindle-targeted drugs in this system. The present findings, that a combination of transcriptional and signal transduction-targeted modulators sensitizes tumor cells synergetically to stress-mediated triggering of cell death and that ribotoxic stress is more efficient in this respect than genotoxic or spindle-targeted stress, bear important implications for the therapeutic exploitation of cellular stress responses. The stepwise sensitization and triggering of cell death in the present system allow separate analysis and manipulation of processes contributing to cellular death susceptibility and of the mechanism responsible for triggering cell death, thus providing the operational basis for further development of this therapeutic approach.

Animals↗

PubMed1998

IgD can largely substitute for loss of IgM function in B cells.

The mu and delta heavy chains of IgM and IgD, the first antibody isotypes expressed during bone-marrow B-cell development, are encoded by a common transcription unit. Expression of the mu chain on the surface of late pre-B cells allows their further development to immature B cells. Coexpression of the delta chain and emigration of the immature B cells to the periphery eventually leads to the development of naive mature IgM/IgD double-positive cells. Although IgM is important in driving B-cell development, the contribution of IgD is not clear. Here we investigate the function of IgD. We generated mice deficient in IgM (IgM-/- mice) by deleting the mu region in embryonic stem cells. IgM-/- mice showed normal B-cell development and maturation, with IgD replacing membrane-bound and secretory IgM. Moreover, specific B-cell responses and isotype class switches occurred during immunization or infection. In contrast to mice deficient in B cells, IgM-/- mice survived infection with vesicular stomatitis virus by developing neutralizing immunoglobulins, but they were more susceptible than wild-type controls with delayed specific immunoglobulin responses. These data lead us to conclude that IgD is largely able to substitute for IgM functions.

Animals↗

PubMed1998

Eosinophils are not required to induce airway hyperresponsiveness after nematode infection.

Eosinophilic inflammation of the airways is believed to play a central role in the pathogenesis of bronchial asthma. Inoculation of mice with the nematode Nippostrongylus brasiliensis induces pulmonary inflammation, characterized by a marked infiltration of eosinophils, subsequent to the migration of parasites through the lungs. Infection is associated with polarized Th2 responses in different strains of mice tested. Thus, this model may be useful to determine the relationship between established pulmonary eosinophilic inflammation, Th2 immune responses and airway changes in a nonallergic background. In the present study, we have used IL-5-deficient mice to evaluate the role of IL-5 in eosinophilic lung inflammation and airway hyperresponsiveness (AHR). In wild-type C57B/6 mice, infection with N. brasiliensis resulted in eosinophil accumulation, associated with extensive lung damage characterized by hemorrhage and alveolar wall destruction, and a strong AHR following methacholine treatment. In IL-5-deficient mice, eosinophil infiltration and the associated lung damage was abrogated. Nonetheless, AHR was unimpaired. Our results suggest that eosinophil accumulation plays a central role in lung damage but is not responsible for the induction of airway constriction following N. brasiliensis infection.

Animals↗

PubMed1998

Intravascular lymphoma presenting as symmetric polyarthritis.

Intravascular lymphoma (IVL) is an uncommon neoplastic disorder characterized by monoclonal intravascular expansion of lymphoid cells. Occlusion of small vessels in various organ systems probably accounts for the broad clinical spectrum of this type of lymphoma, which can closely mimic a variety of diseases, especially vasculitic disorders, and thus lead to delayed clinical diagnosis. This is the first report of a patient who presented with a predominant symptom of symmetric polyarthritis accompanied by fever. While her initial systemic symptoms, such as fever, improved rapidly after initiation of corticosteroid therapy, the response of the polyarthritic joint manifestations was only transient. The patient died of progressive lung involvement and was diagnosed as having IVL by histologic analysis of tissue samples obtained postmortem.

Adrenal Cortex Hormones↗

PubMed1998

Clinical implication of screening p53 gene mutations in head and neck squamous cell carcinomas.

The role of the tumour-suppressor gene p53 in the tumorigenesis of head and neck cancer has been well established, but the clinical significance of p53 alteration is still unclear. A group of 50 patients with head and neck squamous cell carcinoma (HNSCC) were investigated for p53 alterations. DNA was extracted from fresh tumour samples and polymerase chain reaction/single-strand conformation polymorphism analysis was used to detect p53 gene mutations in the region from exon 5 to exon 9. In addition, p53 protein overexpression was assessed by immunohistochemistry using the monoclonal antibody DO-7 on paraffin-embedded tissue sections. p53 gene mutations were found in 45% and p53 protein expression was detected in 61.2% of tumour samples. While p53 protein expression was not correlated with any clinical factors, p53 gene mutations indicated local regional recurrences of HNSCC. The risk of locoregional recurrence was significantly greater in patients with a p53 gene mutation than in patients with the wild-type p53 gene (P = 0.001). Multivariate analysis confirmed p53 gene mutation to be an independently predictive factor for the tumour recurrence (P = 0.0064). When we analysed p53 gene mutation in 12 patients with primary and recurrent tumours, we found that 4 patients (33.3%) had a different p53 gene mutation in the recurrent tumour from that in the original primary tumour. The results indicate that p53 gene mutations and not protein overexpression are valuable predictors for tumour recurrences and for differential diagnosis of a second primary HNSCC.

Biomarkers, Tumor↗

PubMed1998

Drug resistance of secondary acute myeloid leukemia with megakaryoblastic features and p190 BCR-ABL rearrangement.

A 46-year-old female presented with acute myeloid leukemia during complete remission of multiple myeloma after extensive treatment with alkylating agents. Leukemic blasts expressed CD34, platelet esterase and gp IIIa. RT-PCR analyses of peripheral blood cells detected a p190 type BCR-ABL rearrangement and high levels of MDR1. The patient expired during neutropenia shortly after induction chemotherapy. Autopsy revealed persistent blasts in the bone marrow, spleen and liver. 'Secondary' acute myeloid leukemia with megakaryoblastic features and p190-type BCR-ABL rearrangement has not previously been reported. The possibility that the combination of a BCR-ABL rearrangement with overexpression of MDR1 may have contributed to the treatment-refractory course is discussed.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1998

Primary pigmented nodular adrenocortical dysplasia.

A 29-year-old female patient presented clinical features of Cushing's syndrome. Biochemical tests suggested the presence of an autonomously functioning adrenocortical neoplasm. However, the adrenal glands were normal on MRI. Diagnostic adrenalectomy revealed a slightly enlarged organ studded externally and on multiple cut surfaces by small yellow and brown nodules. Microscopically, the nodules were composed of enlarged cortical cells with eosinophilic cytoplasm and nuclear pleomorphism, without mitotic figures. The morphology was consistent with primary pigmented nodular adrenocortical dysplasia (PPNAD). Additional right adrenalectomy was performed for curative treatment of Cushing's syndrome. The pathogenesis of PPNAD is not yet established, though, a defect on chromosome 16 was recently suggested. Since our patient had a malignant melanoma earlier in her history, the PPNAD may be a manifestation of the Carney complex.

Adrenal Cortex↗

PubMed1998

GM-CSF promotes differentiation of a precursor cell of monocytes and Langerhans-type dendritic cells from CD34+ haemopoietic progenitor cells.

Epithelia-associated dendritic cells (DC) including Langerhans cells in the skin (LC) are precursors of lymph node located interdigitating DC (iDC). CD1a+ LC are known to be derived from CD34+ haemopoietic progenitor cells (HPC); however, cells of an intermediate differentiation state that are CD34- and CD1a- have not been identified. Monitoring the differentiation pathway of HPC in the presence of GM-CSF+IL-4, we observed the emergence of a distinct LC precursor population that was CD33+ CD13+ CD4+ CD38+ CD44+ CD34- CD14- CD1a-. The cells could be separated by FACS due to a unique CD44/CD38 expression pattern or by CD44 expression in conjunction with the SSC profile. It was found that they were similarly generated in the presence of GM-CSF alone and were detectable in culture for at least a week. Irrespective of being generated in the presence of GM-CSF+IL-4 or GM-CSF alone, CD44/SSC-sorted precursor cells matured to MHC class II compartments (MIIC) and Birbeck granules (BG) expressing LC, when subsequently cultured in the presence of GM-CSF+IL-4. When IL-4 was omitted, however, the same cells matured to phagocytically active adherent macrophages (Mphi). These culture conditions were associated with a > 4-fold increase in the concentration of IL-6 when compared to those used for LC differentiation. The identification of a distinct oligopotent precursor cell population that can deliberately be induced to give rise to BG+ MIIC+ CD1a+ CD14- LC or to adherent CD14+ Mk further substantiates the close relationship of monocytes and DC and may help to identify its in vivo equivalent.

Antigens, CD34↗