[COVID-19 in old age-The geriatric perspective]

Predominantly the older population is affected by a severe course of COVID-19. The mortality of hospitalized patients with COVID-19 above the age of 80 years is up to 54% in international studies. These observations indicate the necessity to highlight the geriatric perspective on this disease. The diagnostics and treatment of COVID-19 do not differ between younger and older patients but atypical symptoms should be expected more frequently in old age. Older subjects show an increased need for rehabilitation after COVID-19. Paradoxically, increasing rehabilitation demands go along with a reduced availability of geriatric rehabilitation options, the latter being a consequence of closure or downsizing of rehabilitation departments during the pandemic. In general, measures of isolation and quarantine should be diligently balanced as the health and emotional consequences of such measures may be severe in older persons. In light of the poor prognosis of older COVID-19 patients, advanced care planning becomes even more relevant. Caregivers and physicians should be encouraged to compose advanced care directives that also reflect the specific circumstances of COVID-19. Fortunately, current data suggest that the effectiveness of the vaccination with the mRNA-vaccines approved in Germany may be equally high in older compared to younger persons.

[Paraneoplastic subacute degeneration of the cerebellum in non-small cell lung cancer and positive anti-Tr3 antibodies]

Neurological disorders can occur before the diagnosis of a malignoma is set. These disorders are induced by a misguided immune response with antibodies against intracellular or cell surface antigens. One of the most common paraneoplastic diseases is the subacute degeneration of the cerebellum. In most of the cases antibodies against Anti Hu, CRMP5/CV2, Amphiphysin and Ma/Ta are found and small cell bronchial carcinoma, breast cancer and lymphoma are diagnosed. We report about a 67 years old man with cerebellar symptoms and a weight loss of 10 kg who was treated in our clinic. After our diagnostic work up we found a non small cell cancer and diagnosed a subacute degeneration of the cerebellum as a paraneoplastic disorder. We found a high positive titer for Anti-Tr3 antibodies while the rest of the paraneoplastic antibodies described as typically associated with the subacute degeneration of the cerebellum were negative. The Anti-Tr3 antibodies are usually found in patients with Hodgkin and less often Non-Hodgkin disease. After initiation of a tumor specific therapy and intravenous immunoglobulin therapy the cerebellar symptoms decreased. In future follow up examinations we will see if the anti-Tr3 antibodies were associated with the non small cell bronchial carcinoma or if a lymphoma will occur in our patient.

Autologous blood stem cell transplantation in refractory systemic lupus erythematodes with recurrent longitudinal myelitis and cerebral infarction

Autologous hematopoietic stem cell transplantation (ASCT) has the potential to eliminate autoreactive lymphocytes and may represent a therapeutic option for patients with refractory autoimmune diseases. We describe a 19-year old woman with neuropsychiatric systemic lupus erythematodes (NPSLE) presenting with acute longitudinal myelitis and aseptic meningitis. Despite therapy with methylprednisolone and cyclophosphamide (CYC), recurrence of longitudinal myelitis and a disabling stroke-like relapse occurred. Hematopoietic stem cells were mobilized by CYC at 2 g/m2 and G-CSF. The patient was conditioned by CYC at 200 mg/kg and anti-thymocyte globulin and 3.6 = 106 CD34+ cells/kg were infused. Hematopoietic regeneration was observed on day 12 after ASCT. Currently, 18 months after ASCT, the patient is in clinical remission with no evidence for residual serological or neuroradiological activity of SLE. Although a longer follow-up will be needed to reliably assess the efficacy of ASCT in this patient, the present case demonstrates that ASCT may represent a therapeutic option for patients with severe NPSLE.

PEGylated human serum albumin (HSA) nanoparticles: preparation, characterization and quantification of the PEGylation extent

Modification with poly(ethylene glycol) (PEG) is a widely used method for the prolongation of plasma half-life of colloidal carrier systems such as nanoparticles prepared from human serum albumin (HSA). However, the quantification of the PEGylation extent is still challenging. Moreover, the influence of different PEG derivatives, which are commonly used for nanoparticle conjugation, has not been investigated so far. The objective of the present study is to develop a method for the quantification of PEG and to monitor the influence of diverse PEG reagents on the amount of PEG linked to the surface of HSA nanoparticles. A size exclusion chromatography method with refractive index detection was established which enabled the quantification of unreacted PEG in the supernatant. The achieved results were confirmed using a fluorescent PEG derivative, which was detected by photometry and fluorimetry. Additionally, PEGylated HSA nanoparticles were enzymatically digested and the linked amount of fluorescently active PEG was directly determined. All the analytical methods confirmed that under optimized PEGylation conditions a PEGylation efficiency of up to 0.5 mg PEG per mg nanoparticle could be achieved. Model calculations made a 'brush' conformation of the PEG chains on the particle surface very likely. By incubating the nanoparticles with fetal bovine serum the reduced adsorption of serum proteins on PEGylated HSA nanoparticles compared to non-PEGylated HSA nanoparticles was demonstrated using sodium dodecylsulfate polyacrylamide gel electrophoresis. Finally, the positive effect of PEGylation on plasma half-life was demonstrated in an in vivo study in mice. Compared to unmodified nanoparticles the PEGylation led to a four times larger plasma half-life.

Specific biomarkers of receptors, pathways of inhibition and targeted therapies: clinical applications

A deeper understanding of the role of specific genes, proteins, pathways and networks in health and disease, coupled with the development of technologies to assay these molecules and pathways in patients, promises to revolutionise the practice of clinical medicine. In particular, the discovery and development of novel drugs targeted to disease-specific alterations could benefit significantly from non-invasive imaging techniques assessing the dynamics of specific disease-related parameters. Here we review the application of imaging biomarkers in the management of patients with brain tumours, especially malignant glioma. This first part of the review focuses on imaging biomarkers of general biochemical and physiological processes related to tumour growth such as energy, protein, DNA and membrane metabolism, vascular function, hypoxia and cell death. These imaging biomarkers are an integral part of current clinical practice in the management of primary brain tumours. The second article of the review discusses the use of imaging biomarkers of specific disease-related molecular genetic alterations such as apoptosis, angiogenesis, cell membrane receptors and signalling pathways. Current applications of these biomarkers are mostly confined to experimental small animal research to develop and validate these novel imaging strategies with future extrapolation in the clinical setting as the primary objective.

Reperfusion by combined thrombolysis and mechanical thrombectomy in acute stroke: effect of collateralization, mismatch, and time to and grade of recanalization on clinical and tissue outcome

BACKGROUND AND PURPOSE

Our research focuses on interventional neuroradiology (stroke treatment including imaging methods) and general neuroimaging with an emphasis on functional MR imaging. Our aim was to determine the efficacy of revascularization (TIMI) of middle cerebral and/or carotid artery occlusion by means of mechanical recanalization techniques and to evaluate the impact of collateralization, mismatch in perfusion CT, time to revascularization, grade of revascularization on tissue, and clinical outcome in patients with acute ischemic stroke.

MATERIALS AND METHODS

Thirty-one patients with MCA and/or ICA occlusion were included. Ischemic stroke was diagnosed by NECT, CTA, and volume PCT for grading collateralization and mismatch. Time to recanalization was measured from the onset of stroke to the time point of DSA-proved mechanical recanalization. Tissue outcome was calculated by segmentation of infarct size between pre- and postinterventional CT and percentage mismatch lost. Clinical outcome was determined by the mRS.

RESULTS

Twenty-one of 31 patients (61.8%) presented with MCA and 10/31 patients (38.2%), with distal ICA occlusions. Sufficient recanalization (TIMI 2 and 3) was achieved in 23/31 (75%). Clinical evaluation revealed an mRS score of ≤2 in 25.5%. Age (r = 0.439, P = .038) and TIMI (r = 0.544, P = .002) showed the strongest correlation with clinical outcome. Time to recanalization, TIMI score, and mismatch were associated with a good tissue outcome in ANOVA.

CONCLUSIONS

Favorable outcome after mechanical recanalization of acute MCA and ICA occlusion depends on time to and grade of recanalization, mismatch, and collateralization. These results indicate that multimodal stroke imaging is helpful to guide therapy decisions and to indicate patients amenable for mechanical recanalization.

[Primary brain tumors and brain metastases. Symptomatic epilepsy and driving ability - systematic review and expert opinion]

PURPOSE

Primary brain tumors and metastases are common causes of symptomatic epilepsy. Seizures, neurological and neuropsychological deficits can interfere with driving ability. The present paper aims to systematically review the incidence of epileptic seizures in brain tumor patients and to discuss driving ability in the context of the current German guidelines and expert opinions.

METHODS

To evaluate the incidence of epileptic seizures which occur at the beginning and in the course of the disease, we performed a systematic literature research in PubMed from 1960 to 2007. Additionally on the basis of this data we performed a survey collecting expert opinions regarding the driving ability of brain tumor patients from members of the German working groups "Arbeitsgemeinschaft für prächirurgische Epilepsiediagnostik und operative Epilepsietherapie" (Working Group for Presurgical Epilepsy Diagnostics and Operative Epileptic Therapy) and "Neuroonkologische Arbeitsgemeinschaft" (Neuro-oncological Working Group).

RESULTS

The incidence of epileptic seizures depends on the entity, dignity and localization of the tumor. The driving ability of brain tumor patients is not explicitly regulated in Germany. Of the interviewed experts 72% judged the guidelines to be precise enough and 44% did not want to deprive the patients of their driving ability without a first seizure, independent of the individual risk.

DISCUSSION

The available studies are methodologically insufficient and show that a further evaluation is necessary to assess the driving ability. Possible restrictions of the driving ability in patients with a high risk of seizures in the course of the disease have to take into account the balance between individual rights and the interests of the general public.

Imaging noradrenergic influence on amyloid pathology in mouse models of Alzheimer's disease

INTRODUCTION

Molecular imaging aims towards the non-invasive characterization of disease-specific molecular alterations in the living organism in vivo. In that, molecular imaging opens a new dimension in our understanding of disease pathogenesis, as it allows the non-invasive determination of the dynamics of changes on the molecular level. IMAGING OF AD CHARACTERISTIC CHANGES BY microPET: The imaging technology being employed includes magnetic resonance imaging (MRI) and nuclear imaging as well as optical-based imaging technologies. These imaging modalities are employed together or alone for disease phenotyping, development of imaging-guided therapeutic strategies and in basic and translational research. In this study, we review recent investigations employing positron emission tomography and MRI for phenotyping mouse models of Alzheimer's disease by imaging. We demonstrate that imaging has an important role in the characterization of mouse models of neurodegenerative diseases.

In vivo evaluation of the uptake of [(123)I]FIAU, [(123)I]IVFRU and [(123)I]IVFAU by normal mouse brain: potential for noninvasive assessment of HSV-1 thymidine kinase gene expression in gliomas

Radioiodinated 5-iodo-1-(2-fluoro-2-deoxy-beta-D-arabinofuranosyl)uracil (F *IAU) is most commonly used for noninvasive assessment of herpes simplex virus type 1 thymidine kinase (HSV-1-tk) gene expression. However, it does not permeate the intact blood-brain barrier (BBB) because of its moderate lipophilicity. In this work, three iodo-nucleosides, FIAU, IVFRU, and IVFAU, were radiolabeled with iodine-123 and tested for permeation of the BBB in mice and for potential measurement of HSV-1-tk gene expression in gliomas. The results demonstrate that brain uptake and retention of these nucleosides is not directly related to their lipophilicity. The low brain uptake of IVFAU, in conjunction with its higher and constant brain/blood ratio, may reflect greater stability against hydrolysis of the N-glycosidic bond. In vivo PET evaluations of [(124)I]IVFRU and [(124)I]IVFAU in tumor-bearing mice are warranted.

Role of in vivo imaging of the central nervous system for developing novel drugs

Over the past decade imaging technologies employed in clinical neurosciences have significantly advanced. Imaging is not only used for the diagnostic work-up of neurological disorders but also crucial to follow up on therapeutic efforts. Using disease-specific imaging parameters, as read-outs for the efficiency of individual therapies, has facilitated the development of various novel treatments for neurological disease. Here, we review various imaging technologies, such as cranial computed tomography (CT), magnetic resonance imaging (MRI) and spectroscopy (MRS), positron emission tomography (PET) and single-photon emission computed tomography (SPECT), with respect to their current applications in non-invasive disease phenotyping and the measurement of therapeutic outcomes in neurology. In particular, applications in neuro-oncology, Parkinson's disease, Alzheimer's disease, and cerebral ischemia are discussed. Non-invasive imaging provides further insights into the molecular pathophysiology of human diseases and facilitates the design and implementation of improved therapies.

HSV-1 amplicon-mediated post-transcriptional inhibition of Rad51 sensitizes human glioma cells to ionizing radiation

Standard treatment for glioblastoma multiforme and other brain tumors consists of surgical resection followed by combined radio-/chemotherapy. However, radiation resistance of tumor cells limits the success of this treatment, and the tumors invariably recur. Therefore, the selective inhibition of molecular mediators of radiation resistance may provide therapeutic benefit to the patient. One of these targets is the Rad51 protein, which is a key component of the homologous recombinational repair of DNA double-strand breaks. Here, we investigated whether post-transcriptional silencing of Rad51 by herpes simplex virus-type 1 (HSV-1) amplicon vector-mediated short interfering RNA expression can enhance the antitumor effect of radiation therapy. We demonstrate that these vectors specifically and efficiently inhibited the radiation-induced recruitment of Rad51 into nuclear foci in human glioma cells. The combination of vector-mediated silencing of Rad51 expression and treatment with ionizing radiation resulted in a pronounced reduction of the survival of human glioma cells in culture. In athymyc mice, a single intratumoral injection of Rad51-specific HSV-1 amplicon vector followed by a single radiation treatment resulted in a significant decrease in tumor size. In control animals, including mice that received an intratumoral injection of Rad51-specific amplicon vector but no radiation treatment, the tumor sizes increased.

Primary Stroke Unit Treatment Followed by Very Early Carotid Endarterectomy for Carotid Artery Stenosis after Acute Stroke

BACKGROUND

Although it is recognized that carotid endarterectomy (CEA) is the treatment of choice in symptomatic internal carotid artery (ICA) stenosis, in the past, very early CEA has been shown to carry substantial risks. We assessed an interdisciplinary concept of very early CEA in patients with high-grade (>70%) symptomatic ICA stenosis at a single center.

PATIENTS AND METHODS

The course of treatment and outcomes of patients who underwent CEA as early as possible after being referred to the stroke unit for symptoms of transient ischemic attack and stroke were prospectively evaluated, including the following parameters: age, severity of ischemia-related symptoms according to the modified Rankin scale, duration of symptoms until admission, multimodal imaging findings (color-coded duplex, cranial computed tomography, magnetic resonance imaging, positron emission tomography), duration until CEA, perioperative course and complications, as well as duration of in-hospital care.

RESULTS

Fifty consecutive patients (median age 68 years, range 44-90) with clinical and imaging signs of transient ischemic attack (n = 19) or stroke (n = 31) were included from January 2000 until December 2004. All except 1 patient showed a preoperative Rankin < 4. There was a median time period of 6 h between the onset of symptoms and admission (range 1 h to 15 days) and a median duration of 4 days after admission until operation (range 1-21 days). Seven patients underwent CEA of the contralateral, severely stenosed ICA after symptomatic ipsilateral ICA occlusion. Four out of 5 patients who primarily underwent systemic thrombolysis recovered almost completely. Three patients (6%) experienced a clinical deterioration before surgery. In the majority of patients (43/50), CEA was performed under local anesthesia with selective shunt use which became necessary in 26%. Three patients (6%) had postoperative worsening due to new infarcts. In 2 cases, an intracerebral hemorrhage occurred, of which 1 remained asymptomatic. In 1 case, surgical revision was necessary because of an ICA thrombosis without permanent neurological decline. Patients were discharged after a median time of 14.5 days (range 4-44).

CONCLUSIONS

After careful selection and preparation in a stroke unit, patients with acute stroke due to carotid stenosis can undergo very early CEA under local anesthesia with a perioperative risk comparable with the risk of later endarterectomy, therefore preventing very early stroke recurrences.

Stroke after initiation of interferon-beta treatment for relapsing-remitting disseminated white matter disease

BACKGROUND

Interferon-beta (INF-beta) is effective and used in reducing exacerbation frequency and disease progression in multiple sclerosis. In certain circumstances, INF-beta can lead to rare side effects.

AIMS OF THE STUDY

We report the case of a 34-year-old female patient satisfying the McDonald criteria of multiple sclerosis without showing typical pathologic changes in cerebrospinal fluid (CSF). After introduction of INF-beta treatment, she quickly developed further progression of her disseminated neurological symptoms and finally an ischemic cerebral infarction.

METHODS

Evaluation of the patient included arterial angiography, magnetic resonance and positron emission tomography, histopathological assessment as well as a broad spectrum of serum and CSF analysis.

RESULTS

All diagnostic evaluations and the clinical course revealed evidences for a primary angiitis of the CNS. We discuss the possible worsening due to inappropriate INF-beta treatment in cerebral angiitis promoting severe cerebrovascular insufficiency.

CONCLUSION

The authors suggest that all diagnostic multiple sclerosis criteria including typical CSF findings should be ascertained before INF-beta treatment is initiated.

Fatale familiäre Insomnie

Fatal familial insomnia (FFI) is a hereditary prion disease caused by a mutation in codon 178 of the prion protein gene PRNP on chromosome 20. It is characterized by disturbed night sleep, resulting in daily vigilance perturbations and a variety of other neurological symptoms. We present the case of a 46-year-old woman deteriorating despite immunosuppressive treatment which was initiated suspecting cerebral vasculitis as the cause of her progressive neurological symptoms. The correct diagnosis was established only post mortem. Based on the case presented here, we discuss typical clinical symptoms and imaging findings. In particular, we outline how modern diagnostic methods such as positron emission tomography with [(15)O]H(2)O and [(18)F]FDG and single photon emission computed tomography can add valuable information to results from conventionally performed imaging techniques and genetic testing.

Long-term remission in progressive multifocal leukoencephalopathy caused by idiopathic CD4+ T lymphocytopenia: a case report

Progressive multifocal leukoencephalopathy is caused by JC virus, an opportunistic infection of the central nervous system. Antiretroviral treatment for progressive multifocal leukoencephalopathy in human immunodeficiency virus-infected patients is beneficial, but few data exist for patients who are not infected with human immunodeficiency virus. Idiopathic CD4+ T lymphocytopenia excludes human immunodeficiency virus infection. We describe a patient with progressive multifocal leukoencephalopathy with underlying idiopathic CD4+ T lymphocytopenia in whom functional recovery occurred without antiviral therapy.

Dementia in Parkinson disease: Functional imaging of cholinergic and dopaminergic pathways

OBJECTIVE

To assess neurochemical deficits in patients with Parkinson disease (PD) associated dementia (PDD) in vivo.

METHODS

The authors performed combined PET with N-[11C]-methyl-4-piperidyl acetate (MP4A) and 18F-fluorodopa (FDOPA) for evaluation of cholinergic and dopaminergic transmitter changes in 17 non-demented patients with PD and 10 patients with PDD. Data were compared to 31 age-matched controls by a combined region-of-interest and voxel-based Statistical Parametric Mapping analysis.

RESULTS

The striatal FDOPA uptake was significantly decreased in PD and PDD without differences between the groups. The global cortical MP4A binding was severely reduced in PDD (29.7%, p < 0.001 vs controls) and moderately decreased in PD (10.7%, p < 0.01 vs controls). The PDD group had lower parietal MP4A uptake rates than did patients with PD. Frontal and temporo-parietal cortices showed a significant covariance of striatal FDOPA reduction and decreased MP4A binding in patients with PDD.

CONCLUSIONS

While non-demented patients with Parkinson disease had a moderate cholinergic dysfunction, subjects with Parkinson disease associated dementia (PDD) presented with a severe cholinergic deficit in various cortical regions. The finding of a closely associated striatal FDOPA and cortical MP4A binding reduction suggests a common disease process leading to a complex transmitter deficiency syndrome in PDD.

Variability in infectivity of primary cell cultures of human brain tumors with HSV-1 amplicon vectors

We investigated the variability in infectivity of cells in primary brain tumor samples from different patients using an HSV-1 amplicon vector. We studied the infectivity of HSV-1 amplicon vectors in tumor samples derived from neurosurgical resections of 20 patients. Cells were infected with a definite amount of HSV-1 amplicon vector HSV-GFP. Transduction efficiency in primary tumor cell cultures was compared to an established human glioma line. Moreover, duration of transgene expression was monitored in different tumor cell types. All primary cell cultures were infectable with HSV-GFP with variable transduction efficiencies ranging between 3.0 and 42.4% from reference human Gli36 Delta EGFR glioma cells. Transduction efficiency was significantly greater in anaplastic gliomas and meningiomas (26.7+/-17.4%) compared to more malignant tumor types (glioblastomas, metastases; 11.2+/-8.5%; P=0.05). To further investigate the possible underlying mechanism of this variability, nectin-1/HevC expression was analyzed and was found to contribute, at least in part, to this variability in infectability. The tumor cells expressed the exogenous gene for 7 to 61 days with significant shorter expression in glioblastomas (18+/-13 d) compared to anaplastic gliomas (42+/-24 d; P<0.05). Interindividual variability of infectivity by HSV-1 virions might explain, at least in part, why some patients enrolled in gene therapy for glioblastoma in the past exhibited a sustained response to HSV-1-based gene- and virus therapy. Infectivity of primary tumor samples from respective patients should be tested to enable the development of efficient and safe herpes vector-based gene and virus therapy for clinical application.

Novel neuroimaging findings in a patient with cerebral Whipple's disease: a magnetic resonance imaging and positron emission tomography study

The authors report a 43-year-old patient with histopathologically proven cerebral Whipple's disease. Magnetic resonance imaging (MRI) revealed a multilayered left frontal lesion without mass effect, no perifocal brain edema, no contrast enhancement, and a thin shell of fluid signal that presented as an incomplete, open ring. An [11C]methionine positron emission tomography (PET) study showed low uptake below the threshold that is characteristic for brain tumors. In precise co-registration to the MR images, the PET data showed that increased uptake was mainly located in the direct adjacent part of the MRI lesion. The fluid signal on MRI corresponded to the extensive outflow of fluid from the lesion, which was observed during neurosurgical resection, and also to the neuropathological findings. The authors conclude that this cerebral manifestation of Whipple's disease made a unique and hitherto undescribed appearance on MRI; uptake pattern of PET amino acid tracer may help in the preoperative distinction of inflammatory from neoplastic lesions.

Imaging in gene therapy of patients with glioma

Over 10 years ago, the first successful gene therapy paradigms for experimental brain tumors models have been conducted, and they were thought to revolutionize the treatment of patients with gliomas. Application of gene therapy has been quickly forced into clinical trials, the first patients being enrolled in 1994, with overall results being disappointing. However, single patients seemed to benefit from gene therapy showing long-term treatment response, and most of these patients bearing small glioblastomas. Whereas the gene therapy itself has been performed with high sophistication, limited attention has been paid on technologies, which (i) allow an identification of viable target tissue in heterogenous glioma tissue and which (ii) enable an assessment of successful vector administration and vector-mediated gene expression in vivo. However, these measures are a prerequisite for the development of successful gene therapy in the clinical application. As biological treatment strategies such as gene and cell-based therapies hold promise to selectively correct disease pathogenesis, successful clinical implementation of these treatment strategies rely on the establishment of molecular imaging technology allowing the non-invasive assessment of endogenous and exogenous gene expression in vivo. Imaging endogenous gene expression will allow the characterization and identification of target tissue for gene therapy. Imaging exogenously introduced cells and genes will allow the determination of the 'tissue dose' of transduced cell function and vector-mediated gene expression, which in turn can be correlated to the induced therapeutic effect. Only these combined strategies of non-invasive imaging of gene expression in vivo will enable the establishment of safe and efficient vector administration and gene therapy protocols for clinical application. Here, we review some aspects of imaging in gene therapy trials for glioblastoma, and we present a 'proof-of-principle' 2nd-generation gene therapy protocol integrating molecular imaging technology for the establishment of efficient gene therapy in clinical application.

Prospects of molecular imaging in neurology

Molecular imaging aims towards the non-invasive kinetic and quantitative assessment and localization of biological processes of normal and diseased cells in vivo in animal models and humans. Due to technological advances during the past years, imaging of molecular processes is a rapidly growing field, which has the potential of broad applications in the study of cell biology, biochemistry, gene/protein function and regulation, signal transduction, characterization of transgenic animals, development of new treatment strategies (gene or cell-based) and their successful implementation into clinical application. Most importantly, the possibility to study these parameters in the same subject repeatedly over time makes molecular imaging an attractive technology to obtain reliable data and to safe recourse; for example, molecular imaging enables the assessment of an exogenously introduced therapeutic gene and the related alterations of endogenously regulated gene functions directly in the same subject. Therefore, molecular imaging will have great implications especially when molecular diagnostic and treatment modalities have to be translated from experimental into clinical application. Here, we review the three main imaging technologies, which have been developed for studying molecular processes in vivo, the disease models, which have been studied so far, and the potential future applications.

PET-based molecular imaging in neuroscience

Positron emission tomography (PET) allows non-invasive assessment of physiological, metabolic and molecular processes in humans and animals in vivo. Advances in detector technology have led to a considerable improvement in the spatial resolution of PET (1-2 mm), enabling for the first time investigations in small experimental animals such as mice. With the developments in radiochemistry and tracer technology, a variety of endogenously expressed and exogenously introduced genes can be analysed by PET. This opens up the exciting and rapidly evolving field of molecular imaging, aiming at the non-invasive localisation of a biological process of interest in normal and diseased cells in animal models and humans in vivo. The main and most intriguing advantage of molecular imaging is the kinetic analysis of a given molecular event in the same experimental subject over time. This will allow non-invasive characterisation and "phenotyping" of animal models of human disease at various disease stages, under certain pathophysiological stimuli and after therapeutic intervention. The potential broad applications of imaging molecular events in vivo lie in the study of cell biology, biochemistry, gene/protein function and regulation, signal transduction, transcriptional regulation and characterisation of transgenic animals. Most importantly, molecular imaging will have great implications for the identification of potential molecular therapeutic targets, in the development of new treatment strategies, and in their successful implementation into clinical application. Here, the potential impact of molecular imaging by PET in applications in neuroscience research with a special focus on neurodegeneration and neuro-oncology is reviewed.

Molecular imaging of gliomas

Gliomas are the most common types of brain tumors. Although sophisticated regimens of conventional therapies are being carried out to treat patients with gliomas, the disease invariably leads to death over months or years. Before new and potentially more effective treatment strategies, such as gene- and cell-based therapies, can be effectively implemented in the clinical application, certain prerequisites have to be established. First of all, the exact localization, extent, and metabolic activity of the glioma must be determined to identify the biologically active target tissue for a biological treatment regimen; this is usually performed by imaging the expression of up-regulated endogenous genes coding for glucose or amino acid transporters and cellular hexokinase and thymidine kinase genes, respectively. Second, neuronal function and functional changes within the surrounding brain tissue have to be assessed in order to save this tissue from therapy-induced damage. Third, pathognomonic genetic changes leading to disease have to be explored on the molecular level to serve as specific targets for patient-tailored therapies. Last, a concerted noninvasive analysis of both endogenous and exogenous gene expression in animal models as well as the clinical setting is desirable to effectively translate new treatment strategies from experimental into clinical application. All of these issues can be addressed by multi-modal radionuclide and magnetic resonance imaging techniques and fall into the exciting and fast growing field of molecular and functional imaging. Noninvasive imaging of endogenous gene expression by means of positron emission tomography (PET) may reveal insight into the molecular basis of pathogenesis and metabolic activity of the glioma and the extent of treatment response. When exogenous genes are introduced to serve for a therapeutic function, PET imaging may reveal the assessment of the "location," "magnitude," and "duration" of therapeutic gene expression and its relation to the therapeutic effect. Detailed reviews on molecular imaging have been published from the perspective of radionuclide imaging (Gambhir et al., 2000; Blasberg and Tjuvajev, 2002) as well as magnetic resonance and optical imaging (Weissleder, 2002). The present review focuses on molecular imaging of gliomas with special reference on the status and perspectives of imaging of endogenous and exogenously introduced gene expression in order to develop improved diagnostics and more effective treatment strategies of gliomas and, in that, to eventually improve the grim prognosis of this devastating disease.

Molecular Imaging of Gliomas

Gliomas are the most common types of brain tumors. Although sophisticated regimens of conventional therapies are being carried out to treat patients with gliomas, the disease invariably leads to death over months or years. Before new and potentially more effective treatment strategies, such as gene- and cell-based therapies, can be effectively implemented in the clinical application, certain prerequisites have to be established. First of all, the exact localization, extent, and metabolic activity of the glioma must be determined to identify the biologically active target tissue for a biological treatment regimen; this is usually performed by imaging the expression of up-regulated endogenous genes coding for glucose or amino acid transporters and cellular hexokinase and thymidine kinase genes, respectively. Second, neuronal function and functional changes within the surrounding brain tissue have to be assessed in order to save this tissue from therapy-induced damage. Third, pathognomonic genetic changes leading to disease have to be explored on the molecular level to serve as specific targets for patient-tailored therapies. Last, a concerted noninvasive analysis of both endogenous and exogenous gene expression in animal models as well as the clinical setting is desirable to effectively translate new treatment strategies from experimental into clinical application. All of these issues can be addressed by multimodal radionuclide and magnetic resonance imaging techniques and fall into the exciting and fast growing field of molecular and functional imaging. Noninvasive imaging of endogenous gene expression by means of positron emission tomography (PET) may reveal insight into the molecular basis of pathogenesis and metabolic activity of the glioma and the extent of treatment response. When exogenous genes are introduced to serve for a therapeutic function, PET imaging may reveal the assessment of the “location,” “magnitude,” and “duration” of therapeutic gene expression and its relation to the therapeutic effect. Detailed reviews on molecular imaging have been published from the perspective of radionuclide imaging (Gambhir et al., 2000; Blasberg and Tjuvajev, 2002) as well as magnetic resonance and optical imaging (Weissleder, 2002). The present review focuses on molecular imaging of gliomas with special reference on the status and perspectives of imaging of endogenous and exogenously introduced gene expression in order to develop improved diagnostics and more effective treatment strategies of gliomas and, in that, to eventually improve the grim prognosis of this devastating disease.

Molecular and functional imaging technology for the development of efficient treatment strategies for gliomas

Gliomas are the most common types of brain tumors, which invariably lead to death over months or years. Before new and potentially more effective treatment strategies, such as gene therapy, can be effectively introduced into clinical application the following goals must be reached: (1) the determination of localization, extent and metabolic activity of the glioma; (2) the assessment of functional changes within the surrounding brain tissue; (3) the identification of genetic changes on the molecular level leading to disease; and in addition (4) a detailed non-invasive analysis of both endogenous and exogenous gene expression in animal models and in the clinical setting. Non-invasive imaging of endogenous gene expression by means of positron emission tomography (PET) may reveal insight into the molecular basis of pathogenesis and metabolic activity of the glioma and the extent of treatment response. When exogenous genes are introduced to serve for a therapeutic function, PET imaging techniques may reveal the assessment of the location, magnitude and duration of therapeutic gene expression and its relation to the therapeutic effect. Here, we review the main principles of PET imaging and its key roles in neurooncology research.

HSV-1 infected cell proteins influence tetracycline-regulated transgene expression

BACKGROUND

This study investigates elements of herpes simplex virus type 1 (HSV-1) which influence transgene expression in tetracycline-regulated expression systems.

METHODS

Different HSV-1 mutants were used to infect Vero cells that had been transfected with plasmids containing the luciferase gene under the control of tet-off or tet-on tetracycline-regulation systems.

RESULTS

The baseline level of luciferase expression was elevated after infection with HSV-1 mutants lacking one or more immediate early genes encoding transactivating factors: ICP27, ICP4 and ICP0. With the tet-off system, not only was baseline expression elevated, but there was a complete loss of induction upon removal of tet when this regulatory system was brought into the cell by infection with helper virus-free amplicon vectors. Elevation of luciferase expression was also observed upon infection with the same HSV-1 mutants following transfection with a plasmid containing only a CMV minimal promoter driving luciferase (pUHC13-3). Only one HSV mutant (14Hdelta3), which bears a disruption in the transactivation domain of VP16 and is deleted for both ICP4 genes, did not increase baseline luciferase expression after transfection of pUHC13-3. The disregulating effects were dependent on virus dose and were not influenced by treatment with interferon (IFN)-alpha, which suppresses viral gene expression. Additional assays involving cotransfection of pUHC13-3 with a plasmid encoding of the HSV-1 transactivating factor ICP4 revealed that ICP4 was the most potent inducer of gene expression from the tetO/CMV minimal promoter.

CONCLUSION

These results indicate that proteins encoded in the HSV-1 genome, especially the transactivating immediate early gene products (ICP4, ICP27 and ICP0) and the VP16 tegument protein can activate the tetO/ minimal CMV promoter and thereby interfere with the integrity of tetracycline-regulated transgene expression.

Neural precursor cells for delivery of replication-conditional HSV-1 vectors to intracerebral gliomas

Cellular delivery of a replication-conditional herpes simplex virus type 1 (HSV-1) vector provides a means for gene therapy of invasive tumor cells. LacZ-bearing neural precursor cells, which can migrate and differentiate in the brain, were infected with a ribonucleotide reductase-deficient HSV-1 mutant virus (rRp450) that replicates only in dividing cells. Replication of rRp450 in neural precursor cells was blocked prior to implantation into the tumor by growth arrest in late G1 phase through treatment with mimosine. Viral titers in the medium of mimosine-treated, rRp450-infected neural precursor cells were below detection levels 3 days after infection. In culture, after removal of mimosine and passaging, cells resumed growth and replication of rRp450 so that, 7 days later, virus was present in the medium and cell death was evident. Mimosine-treated neural precursor cells injected into established intracerebral CNS-1 gliomas in nude mice migrated extensively throughout the tumor and into the surrounding parenchyma beyond the tumor over 3 days. Mimosine-treated neural precursor cells, infected with rRp450 and injected into intracerebral CNS-1 tumors, also migrated within the tumor with the appearance of foci of HSV-thymidine kinase-positive (TK+) cells, presumably including tumor cells, distributed throughout the tumor and in the surrounding parenchyma over a similar period. This migratory cell delivery method has the potential to expand the range of delivery of HSV-1 vectors to tumor cells in the brain.

Congenital smooth muscle hamartoma. A report of six cases and a review of the literature

Congenital smooth muscle hamartoma (CSMH) represents a proliferation of randomly oriented dermal smooth-muscle bundles. Six patients with CSMH were observed, the largest series to date, and the literature was reviewed. Congenital smooth muscle hamartoma has presented as congenital patches or slightly indurated plaques with prominent overlying hair (88% of cases), or rarely as patches with perifollicular papules without prominent hair (12% of cases). Most lesions (61% of cases) have been somewhat hyperpigmented, but 39% of cases have been flesh colored. Congenital smooth muscle hamartoma has occurred on the torso and proximal extremities, except for one case on the eyebrow and eyelid (present study). A positive pseudo-Darier's sign (temporary induration or piloerection after rubbing) helped to differentiate CSMH from congenital hairy nevo-cellular nevus. Congenital smooth muscle hamartoma is a distinct entity that is at one end of a spectrum that includes Becker's nevus, and should be considered in the differential diagnosis of any congenital hairy lesion.

Jessner's lymphocytic infiltrate in two girls

Two girls demonstrated waxing and waning predominantly facial eruptions. Clinically as well as histologically, the lesions are consistent with lymphocytic infiltrate to Jessner and Kanof and constitute the first reported childhood cases. Although primarily a disease of male adults, this entity should be included in the differential diagnosis of facial plaques in children.

Tinea in tiny tots

Dermatophyte infections in infants and toddlers, with the exception of tinea capitis, are considered rare. We describe representative patients to illustrate the broad clinical spectrum of these infections in this age group. We review possible pathophysiologic mechanisms, diagnostic modalities, and therapeutic regimens. Our experience suggests that involvement of areas other than the scalp may be more common than current estimates suggest. Recognition of affected patients is important in view of the wide differential diagnosis and the efficacy of current treatment.