Christoph Schmitz

Recommendations for straightforward and rigorous methods of counting neurons based on a computer simulation approach.

Any investigation of the total number of neurons in a given brain region must first address the following questions. What is the best method for estimating the total number of neurons? What are the validity and the expected precision of the obtained data? What precision must the estimates attain with respect to the scientific question? In the present study, these questions were addressed using a computer simulation. Virtual brain regions with various spatial distributions of virtual neurons were modeled. The total numbers of virtual neurons in the modeled brain regions were repeatedly estimated by simulation of modern design-based stereology, either by using the fractionator method or by the established method based on the product of estimated neuron density and estimated volume of the reference space. We show that estimates of total numbers of neurons obtained using the fractionator are from a statistical and economical standpoint more efficient than corresponding estimates obtained using the density/volume procedure. Furthermore, the use of two simple prediction methods (one for homogeneous and the other for clustered neuron distributions) permits satisfactory predictions about the variation of presumably any estimates of total numbers of neurons obtained using the fractionator. Finally, we show that assessing the reliability of estimates of mean total neuronal numbers using the ratio between the mean of the squared coefficients of error of the estimates and the squared coefficient of variation of the estimated total neuronal numbers, a frequently employed method in stereological studies, is neither useful nor informative. The present results may constitute a new set of recommendations for the rigorous usage of design-based stereology. In particular, we strongly recommend counting considerably more neurons than is currently done in the literature when estimating total neuronal numbers using design-based stereology.

Deep desulfurization of diesel fuel by extraction with ionic liquids

A new approach for the deep desulfurization of diesel fuels by extraction with ionic liquids is described.

Neurons in the fusiform gyrus are fewer and smaller in autism

Abnormalities in face perception are a core feature of social disabilities in autism. Recent functional magnetic resonance imaging studies showed that patients with autism could perform face perception tasks. However, the fusiform gyrus (FG) and other cortical regions supporting face processing in controls are hypoactive in patients with autism. The neurobiological basis of this phenomenon is unknown. Here, we tested the hypothesis that the FG shows neuropathological alterations in autism, namely alterations in neuron density, total neuron number and mean perikaryal volume. We investigated the FG (analysing separately layers II, III, IV, V and VI), in seven post-mortem brains from patients with autism and 10 controls for volume, neuron density, total neuron number and mean perikaryal volume with high-precision design-based stereology. To determine whether these results were specific for the FG, the same analyses were also performed in the primary visual cortex and in the cortical grey matter as a whole. Compared to controls, patients with autism showed significant reductions in neuron densities in layer III, total neuron numbers in layers III, V and VI, and mean perikaryal volumes of neurons in layers V and VI in the FG. None of these alterations were found in the primary visual cortex or in the whole cerebral cortex. Although based on a relatively small sample of post-mortem brains from patients with autism and controls, the results of the present study may provide important insight about the cellular basis of abnormalities in face perception in autism.

Variation of fractionator estimates and its prediction.

Abstractu2002Over the last decade the so-called ’fractionator’ has become widespread in anatomical and pathological research for obtaining unbiased estimates of total numbers of particles in biological specimens. Several methods have been proposed for predicting the precision (i.e., the variation) of the estimated total numbers of particles using the fractionator (i.e., for predicting the precision of fractionator estimates). However, the validity of these predicting methods has not been tested so far. As it is impossible to do so with biological experiments, it was carried out here by using a computer simulation. Specimens containing particles, with various particle distributional patterns, were modeled, and the total number of particles in the specimens was estimated repeatedly with various modeled sampling schemes. It could be shown that the empirically estimated precision of the modeled fractionator estimates depend on both the particle distributional pattern in a modeled specimen as well as on the applied sampling scheme. Furthermore, considerable differences between the predicted and the empirically estimated precision of the modeled fractionator estimates were found. This was due partly to an incorrect assumption, which serves as the basis for one of the proposed predicting methods, partly to the fact that for some of the proposed predicting methods important contributions to the variation of fractionator estimates have not been considered, and partly to the fact that the mathematical theory, which serves as the basis for all predicting methods proposed so far, can in principle not be the optimum basis for predicting the precision of fractionator estimates. Based on the results of the computer simulation, a new, simple method is proposed for predicting the precision of fractionator estimates.

Nerve cell loss in the thalamic mediodorsal nucleus in Huntington's disease

Abstract We estimated the total neurone number, glial number, and glial index (ratio glial cells/neurone) in the thalamic mediodorsal nucleus (MD) in seven patients suffering from Huntington’s disease (HD; four males, three females, mean age 52.4 ± 13.6 years) and age- and sex-matched controls (four males, three females, mean age 53.6 ± 12.1 years) by means of a stereological protocol. The mean total neurone number (NT¯) in the MD of controls was 2,985,188 ± 174,710, the mean glial number (GT¯; astrocytes, oligodendrocytes) 21,785,008 ± 2,986,678, and the glial index 7.29 ± 0.88. In HD, the average neurone number was decreased by 23.8% to 2,275,321 ± 247,162 (Mann-Whitney U-test P < 0.05), the mean glial number by 29.7 % to 15,318,895 ± 1,722,524 (Mann-Whitney U-test P < 0.05), the glial index was slightly reduced to 6.81 ± 1.06. Gallyas’ impregnation for the demonstration of fibrous astroglia gave strongly positive results in all cases with HD and negative results in the controls. The morpho-functional correlation of the results is complicated because individual variability, presence of segregated and parallel neuronal circuits, and plasticity of the adult human CNS must be considered.

Celloidin mounting (embedding without infiltration) - a new, simple and reliable method for producing serial sections of high thickness through complete human brains and its application to stereological and immunohistochemical investigations.

Celloidin mounting (embedding without infiltration) of the human central nervous system (CNS) proved to be superior to gelatin embedding for the production of serial sections ranging in thickness from 220 to 500 microm. After gallocyanin-staining, a comprehensive neuroanatomical as well as neuropathological survey of the human brain is possible, including diagnosis of Alzheimers disease. Details of a fractionator analysis of the total striatal neuron number are described and the possible quantitative analysis of parallel immunohistochemically stained sections is discussed.

Physikalisch-technische Grundlagen der extrakorporalen Stoßwellentherapie (ESWT)

ZusammenfassungDie extrakorporale Stoßwellentherapie (ESWT) wird gegenwärtig zur Behandlung verschiedener Erkrankungen des Stütz- und Bewegungsapparats wie der Tendinosis calcarea der Schulter bzw. des Rotatorenmanschettensyndroms, der Epicondylitis humeri radialis und der plantaren Fasziitis sowie bei aseptischen Pseudarthrosen eingesetzt. Für die Bewertung der Ergebnisse klinischer Studien und sowie experimenteller Grundlagenarbeiten sind Kenntnisse der physikalischen Parameter extrakorporaler Stoßwellen sowie typischer Parameter der zur Anwendung kommenden Geräte und Verfahren Voraussetzung.Diese Arbeit soll sowohl einen Überblick über technische Grundlagen der ESWT geben als auch messtechnische Grundlagen, Beschreibungen der einzelnen Emissionsverfahren und mögliche Wirkmechanismen darstellen.AbstractExtracorporeal shock waves in orthopaedics are currently applied in the treatment of chronic enthesiopathies such as lateral epicondylitis, plantar heel spur, as well as in calcifying tendinitis of the shoulder or in bony nonunions. Detailed knowledge of physical parameters and properties of shock waves appear to be necessary to determine clinically relevant dose-effect relations and to make shock wave devices, clinical results, and basic science in shock wave therapy more comparable.This study gives an overview of physical parameters and properties in shock wave therapy. Measurement technologies, types of shock wave devices, and mechanisms of shock waves are also described.

Hippocampal interneuron loss in an APP/PS1 double mutant mouse and in Alzheimer’s disease

Hippocampal atrophy and neuron loss are commonly found in Alzheimer’s disease (AD). However, the underlying molecular mechanisms and the fate in the AD hippocampus of subpopulations of interneurons that express the calcium-binding proteins parvalbumin (PV) and calretinin (CR) has not yet been properly assessed. Using quantitative stereologic methods, we analyzed the regional pattern of age-related loss of PV- and CR-immunoreactive (ir) neurons in the hippocampus of mice that carry M233T/L235P knocked-in mutations in presenilin-1 (PS1) and overexpress a mutated human beta-amyloid precursor protein (APP), namely, the APPSL/PS1 KI mice, as well as in APPSL mice and PS1 KI mice. We found a loss of PV-ir neurons (40–50%) in the CA1-2, and a loss of CR-ir neurons (37–52%) in the dentate gyrus and hilus of APPSL/PS1 KI mice. Interestingly, comparable PV- and CR-ir neuron losses were observed in the dentate gyrus of postmortem brain specimens obtained from patients with AD. The loss of these interneurons in AD may have substantial functional repercussions on local inhibitory processes in the hippocampus.

Age-related changes of DNA repair and mitochondrial DNA synthesis in the mouse brain.

Abstract Using quantitative autoradiography, both nuclear DNA repair – measured as nuclear unscheduled DNA synthesis (UDS) – and mitochondrial (mt) DNA synthesis were evaluated in situ for several types of cells in the brains of untreated mice of various age. It was found that distinct types of neuronal cells showed a decline of both UDS and mtDNA synthesis with age, whereas – except for glial cells of the cerebral cortex – no glial or endothelial cells showed age-related alterations of UDS. Together with various data reported in the literature, these patterns of a cell type-specific decrease of UDS and mtDNA synthesis with age in the mouse brain lead to an improved understanding of the complex interrelationships between the molecular events associated with the phenomenon of aging as well as to a new idea regarding the cause of the specific distribution pattern of those cells in the human brain that are affected by the formation of paired helical filaments in Alzheimer’s disease.

Impact of perinatal asphyxia on the GABAergic and locomotor system.

Perinatal asphyxia can cause neuronal loss and depletion of neurotransmitters within the striatum. The striatum plays an important role in motor control, sensorimotor integration and learning. In the present study we investigated whether perinatal asphyxia leads to motor deficits related to striatal damage, and in particular to the loss of GABAergic neurons. Perinatal asphyxia was induced in time-pregnant Wistar rats on the day of delivery by placing the uterus horns, containing the pups, in a 37 degrees C water bath for 20 min. Three motor performance tasks (open field, grip test and walking pattern) were performed at 3 and 6 weeks of age. Antibodies against calbindin and parvalbumin were used to stain GABAergic striatal projection neurons and interneurons, respectively. The motor tests revealed subtle effects of perinatal asphyxia, i.e. small decrease in motor activity. Analysis of the walking pattern revealed an increase in stride width at 6 weeks of age after perinatal asphyxia. Furthermore, a substantial loss of calbindin-immunoreactive (-22%) and parvalbumin-immunoreactive (-43%) cells was found in the striatum following perinatal asphyxia at two months of age. GABA(A) receptor autoradiography revealed no changes in GABA binding activity within the striatum, globus pallidus or substantia nigra. We conclude that perinatal asphyxia resulted in a loss of GABAergic projection neurons and interneurons in the striatum without alteration of GABA(A) receptor affinity. Despite a considerable loss of striatal neurons, only minor deficits in motor performance were found after perinatal asphyxia.