Biomedical subjects

Alf Giese

Publications and source records attributed to Alf Giese.

10 recordsLinked to original sources

PubMed2006

Multiphoton excitation of autofluorescence for microscopy of glioma tissue.

OBJECTIVE: Intraoperative detection of residual tumor tissue in glioma surgery remains an important challenge because the extent of tumor removal is related to the prognosis of the disease. Multiphoton excited fluorescence tomography of living tissues provides high-resolution structural and photochemical imaging at a subcellular level. In this conceptual study, we have used multiphoton microscopy and fluorescence lifetime imaging (4D microscopy) to image cultured glioma cell lines, solid tumor, and invasive tumor cells in an experimental mouse glioma model and human glioma biopsy specimens. MATERIAL AND METHODS: A laser imaging system containing a mode-locked 80 MHz titanium:sapphire laser with a tuning range of 710 to 920 nm, a scan unit, and a time correlated single photon counting board was used to generate autofluorescence intensity images and fluorescence lifetime images of cultured cell lines, experimental intracranial gliomas in mouse brain, and biopsies of human gliomas. RESULTS: Multiphoton microscopy of native tumor bearing brain provided structural images of the normal brain anatomy at a subcellular resolution. Solid tumor, the tumor-brain interface, and single invasive tumor cells could be visualized. Fluorescence lifetime imaging demonstrated significantly different decay of the fluorescent signal in tumor versus normal brain, allowing a clear definition of the tumor-brain interface based on this parameter. Distinct fluorescence lifetimes of endogenous fluorophores were found in different cellular compartments in cultured glioma cells. The analysis of the relationship between the laser excitation wavelength and the lifetime of excitable fluorophores demonstrated distinct profiles for cells of different histotypes. CONCLUSION: Multiphoton excited fluorescence of endogenous fluorophores allows structural imaging of tumor and central nervous system histo-architecture at a subcellular level. The analysis of the decay of the fluorescent signal within specific excitation volumes by fluorescent lifetime imaging discriminates glioma cells and normal brain, and the excitation/lifetime profiles may further allow differentiation of cellular histotypes. This technology provides a noninvasive optical tissue analysis that may potentially be applied to an intraoperative analysis of resection plains in tumor surgery.

Animals↗

PubMed2006

Planning and analyzing robotized TMS using virtual reality.

Transcranial Magnetic Stimulation (TMS) is a powerful method to examine the brain and non-invasively treat disorders of the central nervous system. Magnetic stimulation of the motor cortex results in the activation of corresponding muscle groups. Hereby, accurate placement of the TMS coil to the patient's head is crucial to successful stimulation. We developed a way to position the TMS coil using a robot and navigate it in virtual reality based on an online registration of the cranium relative to 3D magnetic resonance imaging data. By tracking the head and robotic motion compensation, fixation of the patient's head becomes obsolete. Furthermore, a novel method for motor cortex mapping is presented. The robotized TMS system is used to obtain the characteristic field of a TMS coil. This field is registered to the field of motor evoked potential measurements at the patient's head to yield a prediction of the motoric center of a target muscle.

Brain Mapping↗

PubMed2004

Changes in G1-phase populations in human glioblastoma and neuroblastoma cell lines influence p66/Be neutron-induced micronucleus yield.

Some photon resistant tumours are sensitive to neutrons but no predictive methods exist which could identify such tumours. In a recent study addressing this clinically important issue, we demonstrated that relative biologic effectiveness (RBE) values for p(66)/Be neutrons estimated from micronucleus (MN) data correlate positively with RBE values obtained from conventional clonogenic survival data. However, not all photon-resistant cell lines showed high RBE values when the MN endpoint was used. Now, we examine how the functional status of the p53 tumour suppressor gene and radiation-induced changes in cell cycle phase populations may contribute to this discrepancy. No significant association was established between p53 status and MN yield for both photon and neutron irradiation. The data demonstrated that neutron-, but not photon-, induced MN yield is dependent on the intrinsic ability of cells to activate a G1-phase arrest. In cell lines of comparable photon sensitivity, those showing more extensive depletion of the G1 population express significantly more micronuclei per unit dose of neutrons. These results suggest that differences in cell cycle kinetics, and not the p53 status, may constitute an important factor in damage induction by high linear energy transfer (LET) irradiation and need to be considered when radiation toxicity in clinical radiobiology or radiation protection is assessed using damage endpoints.

Beryllium↗

PubMed2004

Technical note: A toy as tool: a low-cost image analysis system for the evaluation of tumor size in experimental small animal models.

Image analysis systems are an essential tool in measurements of size of intraparenchymal tumors or lesions in experimental small animal models. Conventional image analysis systems are relatively expensive. We therefore compared the performance of a professional image analysis system with an inexpensive setup by evaluating tumor size in an orthotopic glioma mouse model. The maximum cross-sectional tumor area of H&E stained brain-slides of two groups of mice (treatment and control group) was measured by two independent investigators using a professional image analysis system (Leica DM IRB microscope) with the Leica Quantimet 500c software, and a low-cost-system (Intel QX3 microscope) with a non-commercial image analysis software. Mean tumor volumes were calculated and the results from each of the image analysis systems, investigators, and treatment effects were compared. The tumor volumes as measured with the low-cost and the professional system differed between -3.7 and +7.5% (P = 0.69-0.99). Measurements made by investigator A and B differed between -7.0 and +3.9% (P = 0.69-0.88). Treatment in all cases significantly reduced the tumor volume between 58.4 and 62.7% (P = 0.0002 or 0.0003), regardless of the investigator or the used image analysis system. We therefore conclude that the QX3 low-cost microscope in combination with a non-commercial image-analysis software represents an inexpensive solution to reliably analyze the size of regions of interest, if they provide a sufficient contrast. However, the low-cost setup due to its low resolution definitely limits a detailed analysis of histologic features.

Animals↗

PubMed2004

Pattern of recurrence following local chemotherapy with biodegradable carmustine (BCNU) implants in patients with glioblastoma.

OBJECTIVE: Recently a randomized placebo-controlled phase III trial of biodegradable polymers containing carmustine has demonstrated a significant survival benefit for patients treated with local chemotherapy. A local chemotherapy applied directly to the resection cavity may act directly on residual tumor cells in adjacent brain possibly leading to a local control of the tumor and increased survival. METHODS: We have analyzed the pattern of recurrence using serial MRI studies of 24 patients treated with GLIADEL Wafers or placebo wafers following resection of glioblastomas. RESULTS: Of 24 patients 11 received carmustine wafers and 13 placebo. The age distribution and Karnowsky performance scores of the two populations were not different. However, the median survival (14.7 versus 9.5 months; P = 0.007) and the time to neurological deterioration (12.9 +/- 4.85 vs. 9.4 +/- 2.73 months; P = 0.035) was significantly longer in the treatment group versus the placebo treated control. Preoperative and follow up MRI studies were evaluated in a blinded fashion. Out of 24 patients that entered the analysis 11 showed clearance of all contrast enhancement following resection of glioblastomas. Seventeen tumors progressed locally and 7 showed different patterns of distant failure. Within the carmustine treated group 8 patients showed a local treatment failure with recurrent tumors immediately adjacent to the resection cavity or progression form a residual tumor. Three patients showed a multifocal distant and local pattern of failure after complete or subtotal removal. In no case the local chemotherapy resulted in a distant recurrence only. However, the time to radiographic progression was 165.1 +/- 80.75 days for the GLIADEL Wafer group and 101.9 +/- 43.06 days for the placebo group (P = 0.023). CONCLUSION: In this subgroup analysis of a phase III trial population both the clinical progression and radiological progression were significantly delayed in patients treated with local chemotherapy, resulting in an increased survival time. Local chemotherapy with carmustine containing wafer implants did not result in an altered pattern of recurrence and did not promote multifocal patterns of recurrence.

Absorbable Implants↗

PubMed2004

Dural arteriovenous fistula of the lumbar spine presenting with subarachnoid hemorrhage. Case report and review of the literature.

The authors report on a patient presenting with subarachnoid hemorrhage (SAH) that was initially attributed to an aneurysm of the right internal carotid artery. During surgical exploration and placement of a clip, however, it was observed that the aneurysm had not ruptured. Diagnostic workup including spinal magnetic resonance imaging revealed a vascular malformation of the lumbar spinal canal within a subarachnoid hematoma. Spinal angiography demonstrated a spinal dural arteriovenous fistula (DAVF) (Type I spinal arteriovenous malformation) with a feeding vessel arising from the L-4 radicular artery. In the literature, SAH due to spinal DAVFs is rare; only cases of dural fistulas of the craniocervical junction and the cervical spine have been reported. This is the first case of SAH that can be attributed to a lumbar DAVF. Although unusual even in cases of cervical DAVF, SAH as a presenting symptom may occur in spinal DAVF of any location. Nontraumatic SAH should not be prematurely attributed to the rupture of an intracranial aneurysm if the clinical findings and imaging results are inconclusive.

Aneurysm, Ruptured↗

PubMed2003

Tumor suppressor p53 inhibits transcriptional activation of invasion gene thromboxane synthase mediated by the proto-oncogenic factor ets-1.

Cancer formation and progression is a complex process determined by several mechanisms that promote cell growth, invasiveness, neo-angiogenesis, and render neoplastic cells resistant to apoptosis. The tumor suppressor p53 and the proto-oncogenic factor ets-1 are important regulators of such mechanisms. While it is well established that p53 and ets-1 influence various aspects of cell behavior by regulating the transcription of specific genes, little is known about the functional relationship between these transcription factors. We found that the gene encoding thromboxane synthase (TXSA), which we recently identified as a factor promoting invasion and resistance to apoptosis in gliomas, is a novel target gene for both p53 and ets-1. We demonstrate that p53 and ets-1 coregulate TXSA in an antagonistic and inter-related manner, with ets-1 being a potent transcriptional activator and p53 inhibiting ets-1-dependent transcription. Negative interference with ets-1 transcription requires functional p53 and is lost in mutant p53 proteins. We show that ets-1 and p53 associate physically in vitro and in vivo and that their interaction, rather than a direct binding of p53 to the TXSA promoter, is required for transcriptional repression of TXSA by wild-type p53. An important implication of our findings is that the loss of p53-mediated negative control over ets-1-dependent transcription may lead to the acquisition of an invasive phenotype in tumor cells.

Base Sequence↗

PubMed2002

Thromboxane synthase inhibitors induce apoptosis in migration-arrested glioma cells.

OBJECTIVE: Because of the wide dissemination of malignant glioma cells by the time that malignant glioma is diagnosed, anti-invasive strategies that are designed to limit their further spread may be of little value unless mechanisms of the invasive cascade can be used to render invasive cells susceptible to cytoreductive treatments. We recently determined that elevated thromboxane synthase gene expression and enzymatic activity are associated with a highly migratory phenotype of glioma cells in vitro and that specific inhibitors of this enzyme block cell migration. Interference with this inherent phenotype of malignant gliomas also affects glioma cell proliferation and apoptosis. METHODS: To study the effect of thromboxane synthase inhibitors on motility, metabolic activity, and cell death, we used five human glioma cell lines, four glioblastoma-derived, low-passage cell cultures, normal human astrocytes, and fibroblasts. Motility was measured in a monolayer migration assay. Caspase activation as an early event in apoptotic cell death was assessed using a caspase 3 cleavage assay. Intracellular deoxyribonucleic acid (DNA) fragmentation was detected by enzyme-linked immunosorbent assay quantification of histone-complexed DNA. Subsequent cell death was scored by trypan blue exclusion. RESULTS: In this study, we demonstrate that the treatment of human glioma cells with the specific thromboxane synthase inhibitor furegrelate leads first to caspase activation (detectable 6 h after treatment), then to DNA fragmentation (24-48 h after treatment) and subsequent cell death. Caspase inhibitors abrogate this effect. Furthermore, the inhibition of thromboxane synthase by furegrelate increases cells' susceptibility to the induction of DNA fragmentation by camptothecin, etoposide, N,N'-bis(2-chloroethyl)-N-nitrosourea, and anti-CD95 antibodies. No induction of apoptosis was observed in normal astrocytes and fibroblasts. CONCLUSION: These data indicate that thromboxane synthase may represent a vortex of divergent signaling cascades that regulate motility and apoptosis in glioma cells. This paradigm may offer a novel perspective in the treatment of patients with malignant gliomas.

Apoptosis↗

PubMedDate not supplied

[Continued physical capacity after head gunshot injury].

The human brain shows a very high density of functionally important structures. Even small lesions may therefore cause clinical symptoms. Penetrating gunshots to the head are presumed to cause immediate incapacitation by subsequent disturbance of cerebral functions. The authors discuss anatomical and functional principles of the terms action, capacity to act and incapacitation and report two illustrative cases with lack of incapacitation following gunshots to the head.

Adult↗

PubMedDate not supplied

High-dose tamoxifen treatment increases the incidence of multifocal tumor recurrences in glioblastoma patients.

BACKGROUND: Multifocal tumor recurrences in glioblastoma patients are described in 4% - 14% of cases. Two recent studies, treating newly diagnosed glioblastoma patients with continuous high-dose tamoxifen (TAM), reported an increased incidence of multifocal tumor recurrences in 45.5% and 33% of study patients. PATIENTS AND METHODS: Fifty newly diagnosed patients with glioblastoma were treated with 3 cycles of carboplatin, continuous high-dose TAM and radiotherapy. Tumor progression was determined on follow-up MRI studies at 3-month intervals and categorized as either local or multifocal. RESULTS: Multifocal tumor recurrence was found in 16 (33%) out of 49 study patients. Compared to tumors which remained local, multifocal tumor recurrences were characterized by a significantly longer median time to tumor progression (41 vs. 23 weeks, Breslow test: p = 0.0123). Multifocal tumor recurrences were mainly observed after an initial response to the study treatment (81%), whereas local regrowth was more often associated with initial treatment failure, i.e. progressive disease (64%). CONCLUSION: The association of the pattern of tumor recurrence with the type of response to TAM treatment suggests that acquired resistance to TAM might be an important contributing mechanism in the development of multifocal glioblastoma disease.

Adult↗