Impact of beta-amyloid-specific florbetaben PET imaging on confidence in early diagnosis of Alzheimer's disease.

BACKGROUND: Early diagnosis of Alzheimer's disease (AD) may be corroborated by imaging of beta-amyloid plaques using positron emission tomography (PET). Here, we performed an add-on questionnaire study to evaluate the relevance of florbetaben imaging (BAY 949172) in diagnosis and consecutive management of probable AD patients. METHODS: AD patients with a clinical diagnosis in accordance with the NINCDS-ADRDA criteria or controls were imaged using florbetaben. Referring physicians were asked on a voluntary basis about their confidence in initial diagnosis, significance of PET imaging results, and their anticipated consequences for future patient care. RESULTS: 121 questionnaires for probable AD patients and 80 questionnaires for controls were evaluated. In 18% of patients who had initially received the diagnosis of probable AD, PET scans were rated negative, whereas in controls 18% of scans were positive. An increase in confidence in the initial diagnosis was frequently reported (80%). Imaging results had a significant impact on the intended patient care, as judged by the referring physicians; this was most prominent in those patients with a contradicting scan and/or a low confidence in the initial diagnosis. CONCLUSION: Florbetaben amyloid imaging increases the overall confidence in diagnosis of AD and may frequently influence clinical decisions and patient management.

Left prefrontal cortex activation during sentence comprehension covaries with grammatical knowledge in children.

Children's language skills develop rapidly with increasing age, and several studies indicate that they use language- and age-specific strategies to understand complex sentences. In the present experiment, functional magnetic resonance imaging (fMRI) and behavioral measures were used to investigate the acquisition of case-marking cues for sentence interpretation in the developing brain of German preschool children with a mean age of 6 years. Short sentences were presented auditorily, consisting of a transitive verb and two case-marked arguments with canonical subject-initial or non canonical object-initial word order. Overall group results revealed mainly left hemispheric activation in the perisylvian cortex with increased activation in the inferior parietal cortex (IPC), and the anterior cingulate cortex (ACC) for object-initial compared to subject-initial sentences. However, single-subject analysis suggested two distinct activation patterns within the group which allowed a classification into two subgroups. One subgroup showed the predicted activation increase in the left inferior frontal gyrus (IFG) for the more difficult object-initial compared to subject-initial sentences, while the other group showed the reverse effect. This activation in the left IFG can be taken to reflect the degree to which adult-like sentence processing strategies, necessary to integrate case-marking information, are applied. Additional behavioral data on language development tests show that these two subgroups differ in their grammatical knowledge. Together with these behavioral findings, the results indicate that the use of a particular processing strategy is not dependent on age as such, but rather on the child's individual grammatical knowledge and the ability to use specific language cues for successful sentence comprehension.

Comparison of immunosorbent assays for the quantification of biomarkers for Alzheimer's disease in human cerebrospinal fluid.

BACKGROUND: The clinical diagnosis of Alzheimer's disease in early stages may be substantiated by the quantification of the biomarkers Abeta42, Abeta40 and total-Tau (t-Tau) in cerebrospinal fluid (CSF). Different commercially available immunosorbent assays yield reliable results, yet the absolute values obtained may differ in between tests. METHODS: We used CSF samples from patients that reported to our memory clinic. Enzyme-linked immunosorbent assays obtained from Innogenetics were used for the quantification of Abeta42 and t-Tau, test kits from IBL International were used to determine Abeta42 and Abeta40 concentrations. The multiplex assay system obtained from Mesoscale Discovery (MSD) Systems was used for the quantification of all three biomarkers. RESULTS: For all biomarkers, the absolute values obtained with different test systems differ. However, the data sets highly correlate for all comparisons, with the MSD test system proving to be slightly more sensitive. Correlation coefficients (c) for the Abeta42 and Abeta40 quantifications lie between c = 0.80 and c = 0.87, and for the t-Tau quantifications we determined c = 0.99. CONCLUSION: We conclude that all assays evaluated give reliable results, yet absolute values obtained have to be assessed differently within the framework of diagnostic procedures, depending on the system used.

GFAP promoter-controlled EGFP-expressing transgenic mice: a tool to visualize astrocytes and astrogliosis in living brain tissue.

We have generated transgenic mice in which astrocytes are labeled by the enhanced green fluorescent protein (EGFP) under the control of the human glial fibrillary acidic protein (GFAP) promoter. In all regions of the CNS, such as cortex, cerebellum, striatum, corpus callosum, hippocampus, retina, and spinal cord, EGFP-positive cells with morphological properties of astrocytes could be readily visualized by direct fluorescence microscopy in living brain slices or whole mounts. Also in the PNS, nonmyelinating Schwann cells from the sciatic nerve could be identified by their bright green fluorescence. Highest EGFP expression was found in the cerebellum. Already in acutely prepared whole brain, the cerebellum appeared green-yellowish under normal daylight. Colabeling with GFAP antibodies revealed an overlap with EGFP in the majority of cells. Some brain areas, however, such as retina or hypothalamus, showed only low levels of EGFP expression, although the astrocytes were rich in GFAP. In contrast, some areas that were poor in immunoreactive GFAP were conspicuous for their EGFP expression. Applying the patch clamp technique in brain slices, EGFP-positive cells exhibited two types of membrane properties, a passive membrane conductance as described for astrocytes and voltage-gated channels as described for glial precursor cells. Electron microscopical investigation of ultrastructural properties revealed EGFP-positive cells enwrapping synapses by their fine membrane processes. EGFP-positive cells were negative for oligodendrocyte (MAG) and neuronal markers (NeuN). As response to injury, i.e., by cortical stab wounds, enhanced levels of EGFP expression delineated the lesion site and could thus be used as a live marker for pathology.

Cell-based delivery of cytokines allows for the differentiation of a doxycycline inducible oligodendrocyte precursor cell line in vitro.

BACKGROUND: Stem cells, having the property of self renewal, offer the promise of lifelong repair of damaged tissue. However, somatic tissue-committed primary stem cells are rare and difficult to expand in vitro. Genetically modified stem-like cells with the ability to expand conditionally provide a valuable tool with which to study stem cell biology, especially the cellular events of proliferation and differentiation. In addition, stem cells may be appropriate candidates for therapeutic applications. METHODS: Double transgenic mice possesing SV40 T antigen (Tag) under the control of the reverse tetracycline-transactivator (rtTA) were used to establish cell lines. One brain cell line was partially characterized by DNA sequencing, morphology, antigen expression using flow cytometry, confocal microscopy, and electrophysiology using the patch clamp technique. Cell cycle analysis was performed using propidium iodide staining; cell viability and H3-thymidine incorporation assays. The ability of this cell line to differentiate was assessed by confocal microscopy following co-culture with stem cells secreting cytokines. RESULTS: We report here the establishment and partial characterization of a cell line derived from the brain tissue of rtTA-SV40 Tag transgenic mice. Analysis of the morphology and antigen markers has shown that this cell line mimics some aspects of primary glial precursors. The results of electrophysiology are consistent with this and suggest that the cell line is derived from O2A glial precursor cells. Cell cycle progression of this cell line is doxycycline-dependent. In the absence of doxycycline, cells become apoptotic. Differentiation into mature type 2 astrocytes and (precursor) oligodendrocytes can be induced upon withdrawal of doxycycline and addition of epithelial stem cells secreting cytokine, such as hIL3 (human Interleukine 3) or hIL6 to the culture. In contrast, co-culturing with hCNTF (human Ciliary NeuroTrophic Factor)-secreting epithelial stem cells did not induce them to mature into progeny cell types. CONCLUSION: The differentiation of this O2A glial precursor line does not occur automatically in culture. Additional external help is required from the cell-based delivery of appropriate transgenic cytokines. Withdrawal of doxycycline from the culture medium removes the proliferation signals and induces a fatal outcome.

Oxidized and reduced Azotobacter vinelandii ferredoxin I at 1.4 A resolution: conformational change of surface residues without significant change in the [3Fe-4S]+/0 cluster.

The refined structure of reduced Azotobacter vinelandii 7Fe ferredoxin FdI at 100 K and 1.4 A resolution is reported, permitting comparison of [3Fe-4S]+ and [3Fe-4S]0 clusters in the same protein at near atomic resolution. The reduced state of the [3Fe-4S]0 cluster is established by single-crystal EPR following data collection. Redundant structures are refined to establish the reproducibility and accuracy of the results for both oxidation states. The structure of the [4Fe-4S]2+ cluster in four independently determined FdI structures is the same within the range of derived standard uncertainties, providing an internal control on the experimental methods and the refinement results. The structures of the [3Fe-4S]+ and [3Fe-4S]0 clusters are also the same within experimental error, indicating that the protein may be enforcing an entatic state upon this cluster, facilitating electron-transfer reactions. The structure of the FdI [3Fe-4S]0 cluster allows direct comparison with the structure of a well-characterized [Fe3S4]0 synthetic analogue compound. The [3Fe-4S]0 cluster displays significant distortions with respect to the [Fe3S4]0 analogue, further suggesting that the observed [3Fe-4S]+/0 geometry in FdI may represent an entatic state. Comparison of oxidized and reduced FdI reveals conformational changes at the protein surface in response to reduction of the [3Fe-4S]+/0 cluster. The carboxyl group of Asp15 rotates approximately 90 degrees, Lys84, a residue hydrogen bonded to Asp15, adopts a single conformation, and additional H2O molecules become ordered. These structural changes imply a mechanism for H+ transfer to the [3Fe-4S]0 cluster in agreement with electrochemical and spectroscopic results.

Calculation of metabolic expenditure and substrate utilization from gas exchange measurements.

At least nine different equations have been published for calculating metabolic expenditure by indirect calorimetry. This study examined the differences between equations when they are used for the nutritional assessment in an intensive care unit (ICU). Oxygen consumption and carbon dioxide production were measured in 36 ICU patients and used to calculate metabolic expenditure with the nine equations. The equations produced differences in metabolic expenditure which averaged from 0.8-96 kcal/day. The largest difference produced by any two of the nine equations was 189 kcal/day. Although differences in original stoichiometric data have resulted in numerous different equations for the calculation of metabolic expenditure, these differences are not clinically important. It makes little difference which equation is used for nutritional assessment in an ICU.

Changes in body composition and dietary intake after gastric partitioning for morbid obesity.

Patients who undergo gastric partitioning for morbid obesity lose weight rapidly in the first year after surgery. This study measured changes in body composition and dietary intake at 3 months, 6 months, and 1 year after gastric partitioning. Body composition was determined by total-body gamma-ray spectrometry. Records of dietary intake were computer analyzed for nutritional content with the Ohio State Nutrient Analysis Data Base. All patients lost a significant amount of weight at 3, 6, and 12 months after surgery. Loss of lean tissue comprised 25% of the total weight loss at 3 months but only 20% of the total at 1 year. Before surgery the mean energy intake was 2592 kcal and the mean protein intake was 92 gm. After 3 months, energy intake was 745 kcal and protein 32 gm. One year after surgery energy intake was 1089 kcal and protein 41 gm per day. We conclude that patients lose a significant amount of lean body tissue in the first 3 months after gastric partitioning but the loss does not continue, and 1 year after surgery some lean tissue is actually regained. This initial loss is due to a combination of a very restrictive dietary regimen and the body's metabolic response to surgery. After the first 3 months adaptation occurs and lean tissue is spared.

Eucaloric substitution of medium chain triglycerides for dietary long chain fatty acids in acquired total lipodystrophy: effects on hyperlipoproteinemia and endogenous insulin resistance.

Previous studies have suggested that reduction of dietary fat intake, with or without caloric restriction, may lead to improvement in certain of the characteristic abnormalities that accompany total lipodystrophy (TLD). We have studied the effects of eucaloric medium chain triglyceride (MCT) substitution for dietary long chain fatty acids in a patient with acquired total lipodystrophy and unusual somatic and visceral anomalies. The patient exhibited insulin resistance, carbohydrate intolerance, striking fasting- and glucose-stimulated hyperinsulinemia, hyperglucagonemia, type V hyperlipoproteinemia, and lipoprotein lipase deficiency on a normal diet. Improvement in chylomicronemia, hypertriglyceridemia, and xanthomatosis occurred during eucaloric MCT substitution. Carbohydrate intolerance decreased and fasting immunoreactive glucagon and insulin concentrations fell 37% and 83%, respectively. Plasma triglyceride polyunsaturated fatty acid concentrations decreased to very low levels. With long term MCT feeding supplemented by polyunsaturated fatty acids, hepatomegaly has gradually decreased, while body weight has remained stable. The patient has not yet required insulin therapy. These observations suggest that the abnormalities in carbohydrate metabolism are closely linked to, and perhaps dependent on, the abnormalities in lipoprotein transport in TLD. Long chain triglyceride restriction and MCT supplementation should be attempted in additional patients with the features of TLD to determine whether this is a generally effective therapeutic approach.