Biomedical subjects

Jürgen Müller

Publications and source records attributed to Jürgen Müller.

16 recordsLinked to original sources

PubMed2005

Concentration and distribution of heavy metals in urban airborne particulate matter in Frankfurt am Main, Germany.

Heavy metal concentrations were measured in airborne dust collected at three sites with different traffic densities from August 2001 to July 2002 in the Frankfurt am Main area. Bulk samples of particulate matter (PM) with an aerodynamic equivalent diameter of <22 microm were collected on cellulose nitrate filters using air filtration devices. Fractionated samples of PM with an aerodynamic equivalent diameter of <10 microm were collected using an eight-stage Andersen impactor. Pb, Cd, Mn, Ni, Zn, V, As, Sb, Cu, Cr, Co, and Ce were determined by inductively coupled plasma sector field mass spectrometry, Pt and Rh were determined by adsorptive voltammetry, and Pd was determined by total reflection X-ray fluorescence analysis. The results show that the highest airborne heavy metal concentrations occurred at the main street with a large volume of traffic. With the exception of Co, V, Ce, and Mn, the heavy metals had an elevated enrichment factor compared to their concentrations in the continental crust. The main street site was especially contaminated with Sb, Zn, Cu, V, and Ni. Motor vehicles are the likely source of emissions. With the exception of Cr, Cu, and Zn, most of the airborne heavy metal concentrations determined for impactor samples deviate slightly from the results for total airborne dust. Heavy metal particle size distributions can be divided into three groups. For metals such as As, Cd, Pb, and V, the main fraction can be found in fine particles with a diameter of <2.1 microm, whereas Ce, Cr, Co, and Ni occur mainly in coarse particles with a diameter of >2.1 microm. Cu, Mn, Sb, Zn, Pt, Pd, and Rh occur in high concentrations in the medium range of the impactor stages (particle diameters of 1.1-4.7 microm). Metal concentrations in fine dust particles are needed to assess the human health risks of their inhalation.

Air Pollutants↗

PubMed2005

Regulation of Raf-1 by direct feedback phosphorylation.

The Raf-1 kinase is an important signaling molecule, functioning in the Ras pathway to transmit mitogenic, differentiative, and oncogenic signals to the downstream kinases MEK and ERK. Because of its integral role in cell signaling, Raf-1 activity must be precisely controlled. Previous studies have shown that phosphorylation is required for Raf-1 activation, and here, we identify six phosphorylation sites that contribute to the downregulation of Raf-1 after mitogen stimulation. Five of the identified sites are proline-directed targets of activated ERK, and phosphorylation of all six sites requires MEK signaling, indicating a negative feedback mechanism. Hyperphosphorylation of these six sites inhibits the Ras/Raf-1 interaction and desensitizes Raf-1 to additional stimuli. The hyperphosphorylated/desensitized Raf-1 is subsequently dephosphorylated and returned to a signaling-competent state through interactions with the protein phosphatase PP2A and the prolyl isomerase Pin1. These findings elucidate a critical Raf-1 regulatory mechanism that contributes to the sensitive, temporal modulation of Ras signaling.

Animals↗

PubMed2005

Osteosarcoma cell lines display variable individual reactions on wildtype p53 and Rb tumour-suppressor transgenes.

BACKGROUND: One of the most widely studied gene therapeutic strategies for cancer is the introduction of tumour-suppressor genes-generally p53-into the target cells. As the genes of p53 and/or retinoblastoma (Rb) are mutated in the major part of osteosarcomas (OS), we aimed to study the effect of p53 and Rb transgenes on a panel of five different osteosarcoma cell lines. METHODS: OS cell lines were transduced by adenoviral vectors delivering the transcription units of the wildtype p53 and the Rb gene. Effects of the transgenes alone and at additional cytostatic stress were studied by proliferation, alive/dead and cell cycle assays. RESULTS: The individual cells lines displayed divergent reactions to p53- or Rb-transgene delivery reaching from cell death (SaOs-2, U2OS at p53 transduction) over stopped or lowered cell division (MG-63, K-HOS, SJSA-1 at p53 and Rb transduction) to nearly unhindered cell growth (U2OS at Rb transduction). In those OS cell lines reacting with lowered cell division to p53 or Rb delivery, cytostatics only moderately intensified the transgene effects. Surprisingly, these reactions were apparently not dependent on the functional status of the cellular p53 and/or Rb genes or on differences in the infectability of the cell lines by the adenoviral vectors. Most interestingly, the respective effects of the p53 or Rb transgenes were not multiplied by simultaneous transduction of both tumour-suppressor genes. CONCLUSIONS: The application of wildtype tumour-suppressor gene therapy on genetically variable osteosarcomas may be efficient only in yet not identified genetic subgroups of this tumour entity. Hyperactive tumour-suppressor transgenes could be an alternative.

Adenoviridae↗

PubMed2005

[The neuronal level of motor activity: determination of motor cortex excitability by TMS].

Transcranial magnetic stimulation as mapping method offers the possibility to measure aspects of motor cortex excitability painlessly and non-invasively. Using this neurophysiological tool, new insights into the effects of central-acting drugs are possible. Particularly striking seems to be the potential of this approach to gain new insights into neurobiological processes associated with neuropsychiatric diseases like schizophrenia or major depression. In combination with genetic aspects, TMS is able to bridge the gap between molecular research and clinical approach.

Antipsychotic Agents↗

PubMed2005

Recombinant anti-EGFR immunotoxin 425(scFv)-ETA' demonstrates anti-tumor activity against disseminated human pancreatic cancer in nude mice.

Pancreatic carcinoma is the fifth leading cause of cancer-related deaths in North America and Europe. Major reasons for the high mortality rate include the inability to detect pancreatic cancer at an early stage, extensive local invasion, and early formation of lymphatic and hematogenous metastases. Consequently, novel and effective therapies need to be developed urgently in order to improve the outcome of patients. Since overexpression of the epidermal growth factor receptor (EGFR) in pancreatic tumors correlates with advanced clinical staging, increased tumor size and reduced patient survival, this receptor represents an appropriate target for immunotherapy. We recently generated the recombinant immunotoxin 425(scFv)-ETA' by genetically fusing the anti-EGFR single chain variable fragment 425(scFv) to a truncated version of Pseudomonas aeroginosa exotoxin A (ETA'). The 425(scFv)-ETA' fusion protein was functionally expressed in the periplasmic space of Escherichia coli and was purified using a combination of metal-ion affinity and anion exchange chromatography. The protein showed specific binding to and toxicity against the EGFR-positive, metastatic pancreatic carcinoma cell line L3.6pl, but not to control cell systems. We report the anti-tumor activity of this recombinant immunotoxin in a disseminated human pancreatic cancer nude mouse model. After intravenous (i.v.) injection of L3.6pl cells into immunodeficient nude mice, both single (20 microg on day 1 after challenge) and repeated (10 microg on days 1, 2, 3 and 4 after tumor cell injection) i.v. administration of 425(scFv)-ETA' resulted in a significant reduction in the average number of lung metastases from 56.25 per animal in the control groups to 0.875 per animal (single injection) and 0.286 per animal (repeated injection), respectively, in the experimental groups. In summary, this is the first report showing an in vivo anti-tumor effect caused by the recombinant immunotoxin 425(scFv)-ETA' against disseminated growing metastatic human pancreatic carcinoma cells. Our data suggest that EGFR-specific antibody toxins could be suitable for further clinical investigation in the development of therapies for pancreatic carcinoma.

ADP Ribose Transferases↗

PubMed2004

[Emotional processing in patients with a dissocial personality disorder subtype "psychopathy" according to PCL-R].

OBJECTIVE: Functional MRI was used to test the effects of the deficient emotional responsiveness of psychopathic patients on cognitive processes. METHOD: We used a Simon-paradigm, in which ten healthy volunteers and ten patients with a diagnosis of "psychopathy" (defined by Hare Psychopathy Checklist Revised) have to select their spatially defined responses on the basis of a nonspatial stimuli feature. For the emotion induction pictures from the International Affective Picture System (IAPS) were selected. At the beginning and intermediated by the Simon-paradigm blocks of positive, negative or neutral pictures were presented. RESULTS: Patients with "psychopathy" exhibited untypical activation patterns in amygdala and prefrontal regions during interferences between negative or positive stimulations and cognitive tasks. CONCLUSIONS: These results demonstrated disturbed regulation of emotion-cognition-interaction in "psychopathy" according to PCL-R.

Adult↗

PubMed2004

[The role of emotions in psychopathology].

OBJECTIVE: In the present study, functional fMRI was used to test the influence of induced emotions on a non-affective, attention-demanding, cognitive task. METHOD: Twelve healthy males viewed blocks of affective pictures. Between picture presentation a Simon-paradigm was presented. In an alternating way blocks with stimulus-response compatible and incompatible trials were presented. RESULTS: Emotion induction differentially influenced cortical activation patterns. In negative mood incompatible trials in contrast to compatible trials lead to significant decrease of activity in emotion related brain areas like the amygdala, the hippocampus and the medial prefrontal cortex. CONCLUSIONS: These results support the hypothesis that negative emotions increase the information processing load and drain attentional resources. To compensate these effects emotion related brain areas must attenuate their activity.

Adult↗

PubMed2004

[Functional neuroanatomy of emotions].

OBJECTIVE: In the present study, functional neuroanatomy of the frontal lobe and limbic system could be uncovered as emotion processing neural substrates. fMRI was used to test the influence of induced emotions on a non-affective, attention-demanding, cognitive task. METHOD: 6 Psychopaths versus 7 controls were analyzed by fMRI with a simon-paradigm after emotion induction. RESULTS: Emotion induction differentially influenced cortical activation patterns in emotion related brain areas like the amygdala and the medial prefrontal cortex. CONCLUSION: Structural-morphological neural areas of emotion regulation in "psychopathy" show variant activation patterns in fMRI. The neural basis of emotional impairment could be a dysfunctional medial prefrontal cortex and amygdala.

Adult↗

PubMed2004

Olfactometry in fMRI studies: odor presentation using nasal continuous positive airway pressure.

We describe a method for generating and presenting olfactory stimuli in functional magnetic resonance imaging (fMRI) studies for humans. The olfactometer is based on principles of air dilution olfactometry and consists of a nasal mask and a nasal Continuous Positive Airway Pressure device, both normally used for patients suffering from obstructive sleep apnea syndrome. The system allows online monitoring and recording of the subject's breathing pattern. Switching between different olfactory conditions can easily be synchronized with the inhalation phase and be controlled by a computer. Besides, switching occurs rapidly and without any optical, acoustic, thermal, or tactile cues for the subject. As an example of implementation we present a fMRI trial of olfaction using pleasant and unpleasant odor stimuli to induce different affective states in healthy subjects. The relatively inexpensive olfactometer is reliable and permits constant odor concentrations during the inherently prolonged imaging studies.

Continuous Positive Airway Pressure↗

PubMed2004

Limited specificity of promoter constructs for gene therapy in osteosarcoma.

Osteosarcoma (OS), a malignant bone neoplasia in childhood, has poor prognosis if metastases appear in the lung. A novel therapeutic approach could consist in a gene therapeutic treatment of OS metastases. However, if promiscuous viral vectors are applied for the delivery of potentially toxic transgenes, their misdelivery into normal tissues could cause severe complications. This problem could be circumvented by application of OS-specific promoters for transgene expression control. We analysed the function of promoters described to be tumour-, osteosarcoma- or osteoblast-specific. Expression rates driven by osteoblast- specific fragments from the collagen1A1-promoter, the human Osteocalcin-promoter, the bone-sialoprotein promoter and the beta-catenin promoter depending on vitamin supplementation were analysed in five OS cell lines, in normal lung fibroblasts and in a non-osteoblastic prostate cancer cell line (LNCaP) by dual luciferase assays. In addition, an unspecific but doxycyclin-repressible promoter construct (pAd.3r-luc) was examined. We found that all constructs were active in OS cell lines to varying extents. The complete human Osteocalcin promoter and the bone-sialoprotein promoter were partially induced by vitamin D3 or C respectively while the pAd.3r-luc activity could be shut down by doxycyclin. In contrast, the human Osteocalcin-promoter was not activated by vitamin D3 in LNCaP cells; its action remained relatively low. Interestingly, excepting the beta-catenin promoter, we measured strong activities of all promoters in lung fibroblast cells. Our study demonstrates that promoter activity should be evaluated not only for the target cells of the gene therapeutic approaches, but also for neighbouring normal tissues. Unspecific but repressible promoters could represent an alternative.

Cell Line, Tumor↗

PubMed2003

Functional analysis of C-TAK1 substrate binding and identification of PKP2 as a new C-TAK1 substrate.

Cdc25C-associated kinase 1 (C-TAK1) has been implicated in cell cycle regulation and Ras signaling through its interactions with two putative substrates, the Cdc25C phosphatase and the MAPK scaffold KSR1. Here, we identify sequence motifs required for stable C-TAK1 association and substrate phosphorylation. Using a mutational approach to disrupt binding of C-TAK1 to KSR1 and Cdc25C, we demonstrate that C-TAK1 contributes to the regulation of these proteins in vivo through the generation of 14-3-3-binding sites. KSR1 proteins defective in C-TAK1 binding had severely reduced phosphorylation at the 14-3-3-binding site in vivo, were constitutively localized to the plasma membrane and had increased biological activity. Disruption of the Cdc25C-C-TAK1 interaction resulted in reduced 14-3-3-binding site phosphorylation and nuclear accumulation of Cdc25C in interphase cells. Finally, utilizing the acquired C-TAK1 binding and substrate phosphorylation data, we identify plakophilin 2 (PKP2) as a novel C-TAK1 substrate. Phosphorylation of PKP2 by C-TAK1 also generates a 14-3-3-binding site that influences PKP2 localization. These findings underscore the importance of C-TAK1 as a regulator of 14-3-3 binding and protein localization.

14-3-3 Proteins↗

PubMed2003

Highly suppressible expression of single-chain interleukin-12 by doxycycline following adenoviral infection with a single-vector Tet-regulatory system.

BACKGROUND: Adenoviral vectors have been shown to efficiently transfer DNA into a wide variety of eukaryotic cells in vitro and in vivo. However, the therapeutic benefit of this approach is limited by severe side effects as a result of uncontrolled transgene expression. METHODS: A bi-directional promoter that controls the desired transgene as well as a tetracycline-suppressible transactivator (tTA) was cloned into the E1-region of E1-deleted recombinant adenoviral vectors. Autoregulation within this construct was obtained by tTA expression under control of the operator, to which tTA binds in the absence of tetracycline. Consequently, binding of tetracycline to tTA results in downregulation of tTA as well as the co-expressed transgene in the infected cell. RESULTS: We were able to suppress luciferase-reporter gene expression by up to 16 000-fold in the presence of doxycycline (dox, 2 micro g/ml). Under control of this tetracycline-regulated system, single-chain interleukin-12 (scIL12) was expressed. Adenovirally mediated expression of this potentially lethal cytokine with strong activation of antitumoral immune response was downregulated by up to 6000-fold in the presence of dox. Subsequently, this downregulation also resulted in a highly significant reduction of interferon-gamma secretion by stimulated splenocytes. These mainly contribute to the toxicity of this immunotherapeutic approach. CONCLUSIONS: With expression levels exceeding those of the cytomegalovirus (CMV) promoter in almost all cell lines tested, these new vectors will also contribute to the safety of adenoviral approaches by controlled expression without compromising on maximum expression levels.

Adenoviridae↗

PubMed2003

[Three-Dimensional Ultrasonic Gait Analysis in Schizophrenic Patients]

Schizophrenic disorders as well as neuroleptic treatment can affect locomotion. The study assessed the influence of neuroleptic treatment on human gait via ultrasonic topometric gait analysis. In a control sample the test system proved high test-retest-reliability. Spatial and temporal gait parameters were assessed in schizophrenic patients without neuroleptic treatment (n = 12) and under treatment with conventional neuroleptics (n = 14) and re-assessed after treatment change to the atypical neuroleptic olanzapine in a repeated measures design. After switch from conventional neuroleptics to olanzapine patients showed an increase of gait velocity (p </= 0.01) and step length (p </= 0.01) whereas the cadence remained stable. Significant differences between the untreated state and treatment with olanzapine were not detectable. We conclude that bipedal gait is affected by conventional neuroleptic treatment. The degree of impairment can be objectively measured by testing spatio-temporal and kinematic gait parameters via three-dimensional ultrasonic gait analysis.

Journal Article↗

PubMed2003

[3-D ultrasound-assisted gait analysis of schizophrenic patients. Comparison between conventional neuroleptics and olanzapine].

Schizophrenic disorders as well as neuroleptic treatment can affect locomotion. The study assessed the influence of neuroleptic treatment on human gait via ultrasonic topometric gait analysis. In a control sample the test system proved high test-retest-reliability. Spatial and temporal gait parameters were assessed in schizophrenic patients without neuroleptic treatment (n = 12) and under treatment with conventional neuroleptics (n = 14) and re-assessed after treatment change to the atypical neuroleptic olanzapine in a repeated measures design. After switch from conventional neuroleptics to olanzapine patients showed an increase of gait velocity (p < or = 0.01) and step length (p < or = 0.01) whereas the cadence remained stable. Significant differences between the untreated state and treatment with olanzapine were not detectable. We conclude that bipedal gait is affected by conventional neuroleptic treatment. The degree of impairment can be objectively measured by testing spatio-temporal and kinematic gait parameters via three-dimensional ultrasonic gait analysis.

Adult↗

PubMed2002

Tumour class prediction and discovery by microarray-based DNA methylation analysis.

Aberrant DNA methylation of CpG sites is among the earliest and most frequent alterations in cancer. Several studies suggest that aberrant methylation occurs in a tumour type-specific manner. However, large-scale analysis of candidate genes has so far been hampered by the lack of high throughput assays for methylation detection. We have developed the first microarray-based technique which allows genome-wide assessment of selected CpG dinucleotides as well as quantification of methylation at each site. Several hundred CpG sites were screened in 76 samples from four different human tumour types and corresponding healthy controls. Discriminative CpG dinucleotides were identified for different tissue type distinctions and used to predict the tumour class of as yet unknown samples with high accuracy using machine learning techniques. Some CpG dinucleotides correlate with progression to malignancy, whereas others are methylated in a tissue-specific manner independent of malignancy. Our results demonstrate that genome-wide analysis of methylation patterns combined with supervised and unsupervised machine learning techniques constitute a powerful novel tool to classify human cancers.

Algorithms↗

PubMedDate not supplied

Age-dependency of insulin-like growth factors, insulin-like growth factor-binding proteins, and acid labile subunit in plasma and wounds of surgical patients.

Wound problems are common in the elderly. We hypothesized that age-related decrements in blood levels of components of the insulin-like growth factor (IGF) system are reflected in the wound environment. In this prospective, observational study IGF-I, IGF-II, IGF-binding protein-2, IGF-binding protein-3, and acid labile subunit were measured by immunoassays in the wound fluid and plasma of young (23.5 +/- 3.3 years) and elderly (78.9 +/- 6.2 years) patients before and daily for 4 days after elective surgery. IGFs, IGFBP-3, and acid labile subunit in plasma were significantly lower in the elderly group (p < 0.0001). The decrements of these proteins in plasma were reflected in corresponding decrements of 25-70% in the wound fluid of elderly patients (p < 0.0001). Additionally, bioavailability of IGF-I was less in the aged. The IGF parameters in the wound displayed a constant ratio with those of blood, suggesting that blood contributes a major share of the IGF that enters the wound during the initial phase of healing. The current data adds to accumulating evidence that a decline in the IGF system in aged patients contributes to the healing deficits observed in the elderly.

Adolescent↗