Search PubMed⌕ Search

Biomedical subjects

A Giese

Publications and source records attributed to A Giese.

At least 19 recordsLinked to original sources
PubMed2003

Cost of migration: invasion of malignant gliomas and implications for treatment.

Tumors of glial origin consist of a core mass and a penumbra of invasive, single cells, decreasing in numbers towards the periphery and still detectable several centimeters away from the core lesion. Several decades ago, the diffuse nature of malignant gliomas was recognized by neurosurgeons when super-radical resections using hemispherectomies failed to eradicate these tumors. Local invasiveness eventually leads to regrowth of a recurrent tumor predominantly adjacent to the resection cavity, which is not significantly altered by radiation or chemotherapy. This raises the question of whether invasive glioma cells activate cellular programs that render these cells resistant to conventional treatments. Clinical and experimental data demonstrate that glioma invasion is determined by several independent mechanisms that facilitate the spread of these tumors along different anatomic and molecular structures. A common denominator of this cellular behavior may be cell motility. Gene-expression profiling showed upregulation of genes related to motility, and functional studies demonstrated that cell motility contributes to the invasive phenotype of malignant gliomas. There is accumulating evidence that invasive glioma cells show a decreased proliferation rate and a relative resistance to apoptosis, which may contribute to chemotherapy and radiation resistance. Interestingly, interference with cell motility by different strategies results in increased susceptibility to apoptosis, indicating that this dynamic relationship can potentially be exploited as an anti-invasive treatment paradigm. In this review, we discuss mechanisms of glioma invasion, characteristics of the invasive cell, and consequences of this cellular phenotype for surgical resection, oncologic treatments, and future perspectives for anti-invasive strategies.

Brain Neoplasms↗
PubMed2003

Intracranial tuberculomas mimicking a malignant disease in an immunocompetent patient.

We present the unusual occurrence of multiple systemic and two central nervous system tuberculomas in an immunocompetent young patient. A large left frontal epidural tuberculoma with transcalvarian extension was removed surgically and chemotherapy was initiated. The patient remained on a chemotherapy with INH, RMP, and EMB and was followed clinically and with MRI scans for 24 months. Findings. The clinical presentation and neuroimaging studies initially suggested malignant disease. Surgical resection of the left frontal lesion was required to relieve the mass effect. The histological evaluation showed a granulomatous inflammation with epithelial and Langhans giant cells, but no acid-fast bacilli. Cultures of the specimens yielded a mixed infection with Corynebacterium species and Staphylococcus epidermidis. Based on the histological findings, chemotherapy for tuberculosis was initiated. Subsequently, Mycobacterium tuberculosis was cultured from the surgical specimen and sputum. Interpretation. Parenchymal CNS tuberculosis with or without extracerebral manifestations may present as a space-occupying lesion. Because a tuberculoma is rarely suspected especially if there is atypical morphology, biopsy is required to establish the diagnosis and expedite specific treatment.

Adolescent↗
PubMed2002

Cyclo-oxygenase inhibitors and thromboxane synthase inhibitors differentially regulate migration arrest, growth inhibition and apoptosis in human glioma cells.

We have previously identified thromboxane synthase as an important regulator of glioma cell migration. Inhibitors of this enzyme abrogate cell motility and induce apoptosis. However, the formation rate of thromboxanes is indirectly dependent on the activity of cyclo-oxygenase, which represents the rate-limiting step in the synthesis of prostaglandins and thromboxanes. In this study we have analyzed the expression of COX-1 and COX-2 in glioma cell lines and biopsies of glial tumors. In normal glia no expression of both COX isoforms was present, however, reactive astrocytes and glial tumors of all grades demonstrated expression of both COX-1 and COX-2. In contrast to inhibitors of thromboxane synthase, selective and non-selective cyclo-oxygenase inhibitors did not block cell motility. Specific COX-2 inhibitors resulted in growth inhibition and induction of intracellular DNA fragmentation indicative of apoptotic cell death. Treatment of glioma cells with thromboxane synthase inhibitors had a synergistic effect on induction of apoptosis by camptothecin, whereas COX inhibitors had not. Furthermore, combined treatment using COX-2 inhibitors and specific thromboxane synthase inhibitors did not show a synergistic increase of apoptosis. These data indicate that COX inhibitors and thromboxane synthase inhibitors influence apoptosis in glioma cells through different pathways. We hypothesize that, in contrast to the COX-2 inhibitors, thromboxane synthase inhibitors block the invasive phenotype of glioma cells and therefore increase the pro-apoptotic disposition of the cells and increase the susceptibility to induced apoptosis. This effect may be independent of prostaglandin synthesis controlled by cyclo-oxygenases.

Apoptosis↗
PubMed2002

Head injury by gunshots from blank cartridges.

BACKGROUND: Blank cartridge handguns are generally underestimated in their capacity to inflict serious and potentially life threatening injuries. The predominant reasons for these injuries are suicide or suicide attempts, followed by accidental injuries. METHODS: A series of 26 gas gunshots to the neurocranium is presented. The injury pattern relevant to neurosurgical practice is illustrated in a case summary of 7 selected cases and the clinical courses as well as outcomes are presented. RESULTS: The injury pattern demonstrates that the energy density of the gas jet and the high temperatures of the exploding gas volume cause extensive soft tissue injuries. In close-range shots the gas jet takes on physical properties of a projectile. In these injuries impression fractures and dislocation of bone fragments are common. CONCLUSIONS: Gas handguns, contrary to public opinion, are dangerous weapons and may inflict potentially fatal injuries to the neurocranium when fired at close range. These weapons are frequently used in criminal or careless activities predominantly by young males. Extensive CNS injuries including hematomas, subarachnoid hemorrhage, foreign body contamination, and increased intracranial pressure are frequently observed.

Adolescent↗
PubMed2001

Identification and validation of P311 as a glioblastoma invasion gene using laser capture microdissection.

The mRNA expression profiles from glioblastoma cells residing at the tumor core and invasive rim of a human tumor resection were compared. From a single tumor specimen, 20,000 single cells from each region were collected by laser capture microdissection. Differential expression of 50-60 cDNA bands was detected. One of the sequences overexpressed by the invasive cells showed 99% homology to the P311 gene, the protein product of which is reported to localize at focal adhesions. Relative overexpression of P311 by invading glioblastoma cells compared with tumor core was confirmed by quantitative reverse transcription-PCR of six glioblastoma specimens after laser capture microdissection collection of rim and core cells. In vitro studies using antisense oligodeoxynucleotides and integrin activation confirmed the role of P311 in supporting migration of malignant glioma cells. Immunochemistry studies confirmed the presence of the P311 protein in tumor cells, particularly at the invasive edge of human glioblastoma specimens.

Amino Acid Sequence↗
PubMed2001

Prion-induced neuronal damage--the mechanisms of neuronal destruction in the subacute spongiform encephalopathies.

Prion diseases are characterized by the accumulation of a specific disease-associated isoform of the prion protein (PrP), termed PrPSc, which is the main, if not the only, component of the infectious agent termed prion. PrPSc is derived by an autocatalytic post-translational process involving conformational changes from the normal host-encoded isoform of the prion protein, termed PrPC. PrPC is a copper-binding glycoprotein attached to the cell membrane of neurons and other cells by means of a GPI anchor. The pattern of neurodegeneration differs between variants of prion disease and is related to the pattern of PrPSc deposition and differences in susceptibility of different cell types to the disease process. The pattern of PrPSc deposition depends on the strain of the agent and the PrP genotype of the host. Strain properties of prions appear to be related to different pathological conformations of PrPSc. Neuronal cell death is a salient feature in the pathology of prion diseases. Histological and electron microscopical studies have shown that cell death in prion disease occurs by apoptosis. Apoptosis of neuronal cells can also be induced in vitro by exposure to PrPSc or a neurotoxic peptide fragment corresponding to amino acids 106-126 of human prion protein (PrP106-126). Both in vitro and in vivo, the toxicity of PrPSc and PrP fragments appears to depend on neuronal expression of PrPC and on microglial activation. Activated microglial cells release pro-inflammatory cytokines and reactive oxygen species. Cell culture experiments suggest an important role of microglia-mediated oxidative stress in the induction of neuronal cell death. Only limited data are available on direct effects of PrPSc on neuronal cells. Potential effects include increased formation of an aberrant transmembrane form of PrP, termed CtmPrP, and changes in plasma membrane properties. In addition to direct and indirect toxic effects of PrPSc, a loss of function of PrPC may contribute to neuronal cell death. Potential mechanisms include disturbances in cerebral copper metabolism and antioxidative defense mechanisms. A better understanding of the pathogenesis of neuronal cell death in prion diseases may also have important therapeutic implications in the future.

Amino Acid Sequence↗
PubMed2001

Treatment of malignant glioma: a problem beyond the margins of resection.

The treatment of malignant glioma remains problematic. Surgical removal followed by external beam irradiation represents a standard treatment that has demonstrated a prolonged time to progression and survival. However, the capacity to locally invade normal brain invariably leads to formation of a recurrent tumor most often immediately adjacent to the site of resection. This clinical everyday experience prompts the hypothesis that improved local control of the tumor may translate into a delayed time to progression and possibly survival, specifically because systemic chemotherapy for most of these tumors has failed to significantly improve survival. Local treatment strategies including chemotherapy, gene therapy, and immunotherapy are rapidly developing and progressing to clinical trials. Several theoretical considerations suggest that these approaches may be promising in the treatment of brain tumors.

Genetic Therapy↗
PubMed2001

Tamoxifen sensitivity-testing of glioblastomas: comparison of in vitro and in vivo results.

BACKGROUND: Only less than half of the patients with malignant gliomas respond to a continuous high dose Tamoxifen (TAM) and/or Carboplatin (CP)-treatment. Therefore, a method for predicting the efficacy of TAM-treatment would be desirable. METHODS: Paralleling a clinical study, the predictive value of in vitro-sensitivity testing of TAM and TAM's metabolite 4-OH-TAM in primary cultures of tumour explants from 15 of a total of 50 patients was examined. Additionally, the influence of TAM, 4-OH-TAM, and CP on the proliferation of established glioblastoma cell lines and of those explanted from athymic nude mice and re-established in cell culture was investigated. Human glioblastomas xenotransplanted subcutaneously into athymic nude mice and subsequently treated with TAM and/or CP were examined in a parallel in vivo-study. FINDINGS: TAM-chemosensitivity-testing of glioblastomas failed to predict the clinical response to TAM-treatment in our patients and did not correlate with the in vivo-TAM-response of tumours xenotransplanted into nude mice. TAM's and 4-OH-TAM's ability to inhibit growth of various glioblastoma cell lines in vitro in very similar concentrations was shown to be a consistent phenomenon which seems to be independent of the in vivo response in either patients or mice as previous hosts. However, CP's antiproliferative effect on glioblastomas in vivo was paralleled by respective in vitro results. Whereas TAM showed to mediate its in vitro antiproliferative effect by inducing apoptosis in most cell lines examined, CP-treatment lead to necrosis of cells. INTERPRETATION: Combining the results obtained from our human and mouse studies, it has to be postulated that host factors other than the sensitivity to TAM of the individual cell, determine the efficacy of TAM-treatment in vivo.

Adult↗
PubMed2001

Glioma cell motility is associated with reduced transcription of proapoptotic and proliferation genes: a cDNA microarray analysis.

Microarray analysis of complementary DNA (cDNA) allows large-scale, comparative, gene expression profiling of two different cell populations. This approach has the potential for elucidating the primary transcription events and genetic cascades responsible for increased glioma cell motility in vitro and invasion in vivo. These genetic determinants could become therapeutic targets. We compared cDNA populations of a glioma cell line (G112) exposed or not to a motility-inducing substrate of cell-derived extracellular matrix (ECM) proteins using two sets of cDNA microarrays of 5,700 and 7,000 gene sequences. The data were analyzed considering the level and consistency of differential expression (outliers) and whether genes involved in pathways of motility, apoptosis, and proliferation were differentially expressed when the motility behavior was engaged. Validation of differential expression of selected genes was performed on additional cell lines and human glioblastoma tissue using quantitative RT-PCR. Some genes involved in cell motility, like tenascin C, neuropilin 2, GAP43, PARG1 (an inhibitor of Rho), PLCy, and CD44, were over expressed; other genes, like adducin 3y and integrins, were down regulated in migrating cells. Many key cell cycle components, like cyclin A and B, and proliferation markers, like PCNA, were strongly down regulated on ECM. Interestingly, genes involved in apoptotic cascades, like Bcl-2 and effector caspases, were differentially expressed, suggesting the global down regulation of proapoptotic components in cells exposed to cell-derived ECM. Overall, our findings indicate a reduced proliferative and apoptotic activity of migrating cells. cDNA microarray analysis has the potential for uncovering genes linking the phenotypic aspects of motility, proliferation, and apoptosis.

Apoptosis↗
PubMed2001

Decreased prion protein expression in human peripheral blood leucocytes from patients with paroxysmal nocturnal haemoglobinuria.

The cellular isoform of the prion protein (PrPC) is a cell surface glycoprotein attached to the outer leaflet of the plasma membrane by a glycosylphosphatidyl-inositol (GPI) anchor. PrPC is involved in the pathogenesis of prion diseases and has recently been shown to play a role in haemopoietic cell activation and proliferation. We have used the PrPC-specific monoclonal antibody (mAb) 3F4 in a flow cytometry approach to analyse the constitutive expression of PrPC on human peripheral blood (PB) cell populations from patients with paroxysmal nocturnal haemoglobinuria (PNH), which are characterized by a deficiency of GPI-linked cell surface proteins. Comparable PrPC expression levels (P > 0.05), quantified as mean fluorescent intensity, were measured on lymphocytes isolated from normal donors (n = 10) and patients with PNH (n = 5), whereas PNH PB monocytes and granulocytes exhibited substantially lower PrPC surface immunoreactivity than their normal counterparts (P < 0.05). More detailed histogram analyses of the PNH PB leucocytes revealed that PrPC was absent in PNH granulocytes, but was normally expressed in lymphocytes from four out of five patients. However, in one patient a bimodal distribution of 3F4 mAb staining was observed, indicating the presence of a PrPC-deficient lymphocyte subpopulation. In conclusion, our results show that PNH haemopoietic cells are deficient in cell surface-bound PrPC.

Adult↗
PubMed2001

Lysine and polyamines are substrates for transglutamination of Rho by the Bordetella dermonecrotic toxin.

Bordetella dermonecrotic toxin (DNT) catalyzes the transglutamination of glutamine-63/61 of Rho GTPases, thereby constitutively activating Rho proteins. Here we identified second substrates for transglutamination of RhoA by DNT. The enzymatically active fragment of DNT (residues 1136 to 1451, DeltaDNT) induced the incorporation of L-[(14)C]lysine in RhoA in a concentration-dependent manner. Also, Rac and Cdc42, but not Ras, were transglutaminated with lysine by DeltaDNT. Transglutamination of the GTPase with L-lysine inhibited intrinsic and Rho-GAP-stimulated GTP hydrolysis of RhoA. In contrast to lysine, treatment of RhoA with alanine, arginine, and glutamine were not able to substitute for lysine in the transglutamination reaction. DNT increased the incorporation of L-[(14)C]lysine into embryonic bovine lung cells. Microinjection of GST-RhoA together with the enzymatically active DNT fragment into Xenopus oocytes, subsequent affinity purification of modified GST-RhoA, and mass spectrometry identified attachment of putrescine or spermidine at glutamine-63 of RhoA. A comparison of putrescine, spermidine, and lysine as substrates for DNT-induced transglutamination of RhoA revealed that lysine is a preferred second substrate at least in vitro.

Animals↗
PubMed2001

Porcine urinary tract as a training model for ureteroscopy.

OBJECTIVES: Endourological procedures as ureteroscopy require an advanced level of skills. To facilitate the training of the proper technique, simulators are helpful. Nonbiological models, useful to learn the basic steps, do not represent the clinical situation in an ideal way. We therefore looked for a biological but nevertheless easily available model. METHODS: The complete urinary tract is dissected off the retroperitoneal organ package of freshly slaughtered pigs. RESULTS: The porcine urinary tract model allows for training all aspects of diagnostic and therapeutic ureteroscopy including lithotripsy and stenting in a way which is almost identical to the clinical situation in humans. CONCLUSIONS: The porcine urinary tract model is an ideal ex vivo model. Concerning 'tissue feeling' and anatomic relations, it is superior to nonbiological simulators. Nevertheless, it is quite easily available and inexpensive. In training courses, we have used it with great success.

Animals↗
PubMed2001

Death-associated protein 3 (Dap-3) is overexpressed in invasive glioblastoma cells in vivo and in glioma cell lines with induced motility phenotype in vitro.

PURPOSE: To discover the genetic determinants of glioma invasion in vivo, we compared the mRNA expression profiles of glioblastoma cells residing at the tumor core versus those at the invasive rim of a human tumor resection. EXPERIMENTAL DESIGN: From a single glioblastoma specimen, 20,000 individual cells from each region (core and invasive rim) were collected by laser capture microdissection and analyzed by mRNA differential display. Differential expression of gene candidates was confirmed by laser capture microdissection and quantitative reverse transcription-PCR in additional glioblastoma multiforme specimens, and the role in migration was further evaluated in glioma cell lines in vitro. RESULTS: Reproducible overexpression the death-associated Protein 3 (Dap-3) mRNA (NM 004632, GenBank; also reported as human ionizing resistance conferring protein mRNA, HSU18321, GenBank) by invasive cells was identified. Although the full-length Dap-3 protein has been described as proapoptotic, the NH(2)-terminal fragment can act in a dominant negative way resulting in protection from programmed cell death. In glioma cell lines T98G and G112 with an induced motility phenotype, Dap-3 was up-regulated at the mRNA and protein level as assessed by quantitative reverse transcription-PCR, cDNA microarray, and Western blot analysis. These cells showed an increased resistance to undergo camptothecin-induced apoptosis, which was overcome by effective Dap-3-antisense treatment. Antisense treatment also decreased the migration ability of T98G cells. CONCLUSIONS: Dap-3 is up-regulated in invasive glioblastoma multiforme cells in vivo and in glioma cells with an induced motility phenotype in vitro. When migration is activated, Dap-3 is up-regulated and cells become resistant to apoptosis. These findings suggest that Dap-3 confers apoptosis-resistance when migration behavior is engaged.

Apoptosis↗
PubMed2000

Tamoxifen-resistant glioma-cell sub-populations are characterized by increased migration and proliferation.

Multifocal tumor recurrence of glioblastomas occurs in up to 14% of patients. In a parallel phase-II-study investigating post-operative treatment with tamoxifen (TAM), carboplatin and radiation therapy for glioblastomas, 16 of 49 patients (33%) showed multifocal recurrence, which developed after a mean of 46 weeks, raising the question of an association with therapy. We studied the interrelation of proliferation and migration in the presence of different protein-kinase-C(PKC) inhibitors (TAM, staurosporine, hypericin) in 2 glioma cell lines. In addition, 3 cell lines were selected for TAM resistance by repeated cycles of treatment with sub-lethal concentrations of TAM. The proliferative capacity and the invasive potential of selected sub-populations were assessed using growth-curve experiments, monolayer migration, and cell-adhesion assays. Treatment with all PKC inhibitors tested resulted in a dose-dependent decrease of proliferation, while motility was altered only at significantly higher doses. Resistance to TAM occurred in all 3 selected cell lines. The TAM-resistant sub-populations showed significantly increased proliferation, migration and adhesion as compared with the parental (non-selected) cell line. The higher incidence of multifocal disease after TAM treatment was paralleled by increased migratory potential of TAM-treated cells in vitro.

Anthracenes↗
PubMed2000

Ultrasensitive detection of pathological prion protein aggregates by dual-color scanning for intensely fluorescent targets.

A definite diagnosis of prion diseases such as Creutzfeldt-Jakob disease (CJD) relies on the detection of pathological prion protein (PrP(Sc)). However, no test for PrP(Sc) in cerebrospinal fluid (CSF) has been available thus far. Based on a setup for confocal dual-color fluorescence correlation spectroscopy, a technique suitable for single molecule detection, we developed a highly sensitive detection method for PrP(Sc). Pathological prion protein aggregates were labeled by specific antibody probes tagged with fluorescent dyes, resulting in intensely fluorescent targets, which were measured by dual-color fluorescence intensity distribution analysis in a confocal scanning setup. In a diagnostic model system, PrP(Sc) aggregates were detected down to a concentration of 2 pM PrP(Sc), corresponding to an aggregate concentration of approximately 2 fM, which was more than one order of magnitude more sensitive than Western blot analysis. A PrP(Sc)-specific signal could also be detected in a number of CSF samples from patients with CJD but not in control samples, providing the basis for a rapid and specific test for CJD and other prion diseases. Furthermore, this method could be adapted to the sensitive detection of other disease-associated amyloid aggregates such as in Alzheimer's disease.

Animals↗
PubMed2000

Clinical and differential diagnosis of Creutzfeldt-Jakob disease.

Until recently, the clinical diagnosis of CJD relied mainly on three criteria. These include patient history (rapidly progressive dementia), neurological findings (ataxia, pyramidal/extrapyramidal signs, myoclonus, akinetic mutism) and typical electroencephalographic (EEG) findings. These criteria are fulfilled in typical cases. The occurrence or increase of certain proteins in cerebrospinal fluid (CSF; 14-3-3, neuron-specific enolase) now provide important adjuncts in recognizing variant forms. Although these proteins can be detected in other neurological diseases accompanied with substantial brain damage such as encephalitis, they are also characterized by their high sensitivity and specificity with regard to other dementing processes (Alzheimer and vascular dementia). The increase in the number of positive cases during the last years in Germany reflects an improved case ascertainment rather than the appearance of the variant CJD (vCJD). Although several recent cases with a long duration of the disease were actually recognized, they did not reveal the typical florid plaques at autopsy. They were revealed as a rare variant of sporadic CJD, which is characterized by homocygosity for valine at codon 129 and PrP(Sc) type 1. This variant is positive for the 14-3-3 protein in CSF. Further subtypes described by Parchi et al. can also be characterized by a certain pattern of clinical symptomatology, EEG- and 14-3-3-findings. In addition, differential diagnosis revealed some treatable dementias among the most common diseases (Alzheimer and vascular dementia) such as herpes encephalitis, multiple sclerosis and Hashimoto encephalitis, particularly in the younger age group.

Cerebrospinal Fluid↗
PubMed2000

Putting prions into focus: application of single molecule detection to the diagnosis of prion diseases.

Prion diseases are characterized by the cerebral deposition of an aggregated pathological isoform of the prion protein (PrP(Sc)) which constitutes the principal component of the transmissible agent termed prion. In order to develop a highly sensitive method for the detection of PrP(Sc) aggregates in biological samples such as cerebrospinal fluid (CSF), we used a method based on Fluorescence Correlation Spectroscopy (FCS), a technique which allows detection of single fluorescently labeled molecules in solution. Within the FCS setup, fluorescent photons emitted by molecules passing an open volume element defined by the beam of an excitation laser focussed into a diffraction-limited spot are imaged confocally onto a single photon counting detector. Aggregates of PrP(Sc) could be labeled by co-aggregation of probe molecules such as monomeric recombinant PrP or PrP-specific antibodies tagged with a fluorescent dye. In addition to slow diffusion, labeled aggregates are characterized by high fluorescence intensity, which allows detection and quantification by analysis of fluorescence intensity distribution. To improve detection of rare target particles, the accessible volume element was increased by scanning for intensely fluorescent targets (SIFT). To further improve sensitivity and specificity, two different probes were used simultaneously in a two-color setup. In a diagnostic model system of CSF spiked with purified prion rods, dual-color SIFT was more sensitive than Western blot analysis. In addition, a PrP(Sc)-specific signal was also detected in a number of CSF samples derived from CJD patients but not in controls.

Animals↗