Biomedical subjects

Bente Pakkenberg

Publications and source records attributed to Bente Pakkenberg.

At least 19 recordsLinked to original sources

PubMed2007

Excess of neurons in the human newborn mediodorsal thalamus compared with that of the adult.

The aim of this study was to quantify the total number of neurons and glial cells in the mediodorsal nucleus of the thalamus (MD) of 8 newborn human brains, in comparison to 8 adult human brains. The estimates of the cell numbers were obtained using the stereological principles of the optical fractionator. In the case of the adults, the total number of neurons in the entire MD was an average of 41% lower than in the newborn, which was statistically highly significant (P < 0.001). The estimated average total number of neurons in MD thalamus of the newborns was 11.2 million (coefficient of variation [CV] = standard deviation/mean = 0.16), compared with the adults' 6.43 million (CV = 0.15). The glial cell numbers were substantially higher in the adult brains, with an increase of almost 4 times from 10.6 million at birth to 36.3 million in the fully developed adult brain. This is the first demonstration of a higher number of human neurons in the brain of newborns compared with the adult.

Adult↗

PubMed2006

The prefrontal cortex in the Göttingen minipig brain defined by neural projection criteria and cytoarchitecture.

In an attempt to delineate the prefrontal cortex (PFC) in the Göttingen minipig brain the distribution of reciprocal thalamocortical projections was investigated using anterograde and retrograde tracing techniques and evaluated in relation to the specific cytoarchitectonic organization. Tracers were visualized using standard immunohistochemistry or evaluated in vivo using manganese (Mn2+) as an MRI paramagnetic tracer. The in vivo tract tracing turned out to be very sensitive with a high correspondence to the histological labelling. Tracers injected into the mediodorsal thalamus labelled the medial and rostral pole of the frontal lobe as well as the anterior cingulate, anterior insular and dorsomedial frontal cortices. Subsequently, the reciprocity and specificity of these connections were tested from injections into the traced frontal cortices indicating that the PFC has cortical connections to different parts of the MD nucleus. Although the granular layer IV, characteristic of primate PFC could not be identified, both cytoarchitectonic and connectional data suggests that the Göttingen minipig has a structurally divided prefrontal cortex. Stereological estimates of PFC volume showed that the Göttingen minipig PFC constitutes about 24% of the total neocortex volume and 10% of the total brain volume.

Animals↗

PubMed2006

The postnatal development of cerebellar Purkinje cells in the Göttingen minipig estimated with a new stereological sampling technique--the vertical bar fractionator.

The postnatal development of total number and perikaryon volume of cerebellar Purkinje cells was estimated in the Göttingen minipig cerebellar cortex using a new stereological approach, the vertical bar fractionator. Data were obtained from the brains of five neonate and five adult female Göttingen minipigs. The total number of Purkinje cells ranged from 1.83 x 10(6) in the neonate to 2.82 x 10(6) in the adult Göttingen minipig. The number-weighted mean perikaryon volume of Purkinje cells increased concurrently from around 6,800 microm(3) in the neonate to 17,600 microm(3) in the adult. The study demonstrates that a pronounced postnatal neurogenesis in Purkinje cell number and perikaryon volume is part of the growth and development of the cerebellum in the Göttingen minipig. The Purkinje cells of the Göttingen minipig were found to be substantially large compared with human and represents the largest cells described hitherto from mammalian cerebella. The vertical fractionator is a new sampling technique, which allows the combination of a fractionator design on vertical bar sections excluding exhaustive sampling and bias from artificial edges. By design, the sections are perfect stereological vertical sections and provide the basis for unbiased estimates of total number of structural entities in the brain, including surface area, fibre length and particle volume.

Animals↗

PubMed2006

The postnatal development of neocortical neurons and glial cells in the Göttingen minipig and the domestic pig brain.

The first mathematically unbiased estimates of neocortical cell numbers are presented from the developing pig brain, including a full description of tissue processing and optimal sampling for application of the stereological optical fractionator method in this species. The postnatal development of neocortical neurons and glial cells from the experimental Göttingen minipig was compared with the postnatal development of neocortical neurons in the domestic pig. A significant postnatal development was observed in the Göttingen minipig brain for both neuronal (28%; P=0.01) and glial cells (87%; P<0.01). A corresponding postnatal development of neurons was not detected in the domestic pig brain. The reason for this strain difference is not known. The mean total number of neocortical neurons is 324 million in the adult Göttingen minipig compared with 432 million in the domestic pig. The glial-to-neuron cell ratio is around 2.2 in the adult Göttingen minipig. Based on these results, the domestic pig seems to be a more suitable model for evaluating the effects of developmental insults on human brain growth and neuronal development than the Göttingen minipig.

Animals↗

PubMed2005

Immunohistochemical visualization of neurons and specific glial cells for stereological application in the porcine neocortex.

The pig is becoming an increasingly used non-primate model in basic experimental studies of human neurological diseases. In spite of the widespread use of immunohistochemistry and cell type specific markers, the application of immunohistochemistry in the pig brain has not been systematically described. Therefore, to facilitate future stereological studies of the neuronal and glial cell populations in experimental neurological diseases in the pig, we established a battery of immunohistochemical protocols for staining of perfusion fixed porcine brain tissue processed as free floating cryostat-, vibratome- or paraffin sections. Antibodies against NeuN, GFAP, S100-protein, MBP, CNPase, CD11b, CD68 (KP1), CD45 and Ki67 were evaluated, and all except CD68 and CD45 resulted in staining of high quality in either type of tissue. Each staining was evaluated with respect to specificity and sensitivity in identification of the individual cells, and for penetration of the staining and maintenance of section thickness above 25 microm, necessary for stereological cell counting. In the cases of NeuN, CNPase, CD11b and Ki67 the staining met the demands to be applicable in stereological analyses using the optical disector. In conclusion, all protocols will be applicable in studies of pathological and neurochemical changes in the porcine brain, and a few protocols applicable for stereology.

Animals↗

PubMed2005

Assessment of in vivo MR imaging compared to physical sections in vitro--a quantitative study of brain volumes using stereology.

The object of the present study was to compare stereological estimates of brain volumes obtained in vivo by magnetic resonance imaging (MRI) to corresponding volumes from physical sections in vitro. Brains of ten domestic pigs were imaged using a 3-T scanner. The volumes of different brain compartments were obtained from MR images by two observers and from physical sections using the Cavalieri estimator in combination with point counting. Paired t tests revealed no significant differences between the two methods for any of the five compartments considered, except for the basal gray compartment. However, although intraobserver difference of MRI estimates was acceptable, the interobserver difference was not. A statistical highly significant difference of 11-41% was observed between observers for volume estimates of all compartments considered. The study demonstrates that quantitative MRI is susceptible to observer dependent interpretation of images.

Algorithms↗

PubMed2005

Increased volume of the pigmented neurons in the locus coeruleus of schizophrenic subjects: a stereological study.

The locus coeruleus is the largest cluster of noradrenaline-producing neurons in the brain and has been involved in regulating attention. The neurotransmitter system contributes to the initiation and maintenance of forebrain activity as well as modulation of the collection and processing of sensory information. This makes locus coeruleus a target of interest in the study of possible structural changes in the brains of subjects with chronic schizophrenia. Uniform sampling and optical disectors were used for estimation of total neuron numbers and the rotator principle for estimation of mean cell volume. This study estimated the bilateral total number of pigmented neurons in the locus coeruleus of schizophrenic and control subjects and found no difference between the two; schizophrenic subjects have 37,400 (coefficient of variation=CV=SD/mean=0.28), control subjects have 35,500 (CV=0.19), p=0.64. The average volume of the cell perikaryon of pigmented neurons was measured in both groups and showed a significant larger cell volume in the locus coeruleus of schizophrenic compared to control subjects; mean locus coeruleus cell volume was 58,400 microm(3) (CV=0.31) in schizophrenic subjects, which is 55% larger than the 37,600 microm(3) (CV=0.33) found in control subjects, a difference of 20,800 microm(3) (p=0.009). The fixation time was significantly longer for the schizophrenic brains with an average of 169 months compared to 88 months for the control brains. No relation was found between total numbers or geometric mean volume of the pigmented cells and fixation time.

Adult↗

PubMed2005

No global loss of neocortical neurons in Parkinson's disease: a quantitative stereological study.

The global total number of neocortical neurons was estimated in 10 patients with Parkinson's disease (PD; mean age, 74.8 years; range, 68-83) and compared to 12 comparison subjects (mean age, 75.8 years; range, 70 - 84). The total mean neocortical neuron number in the patients with PD was 18.6 x 10(9) with a coefficient of variation (CV = SD/mean) of 0.18, which was not statistically significantly different from that of the controls (18.8 x 10(9); CV = 0.16; P = 0.90). In contrast to some studies reporting neocortical atrophy this was not confirmed in our study, where the mean volume of neocortex was the same in the two groups (P = 0.59). No difference was found in the volume of white matter, central gray structures, archicortex, or the ventricular system between the two groups. Most patients with PD develop cognitive disturbances with time, and this study cannot exclude that local neuron loss in specific subpopulations of neocortical neurons or cell loss in small but essential neocortical subregions may be part of the structural defects of PD.

Aged↗

PubMed2005

The size distribution of neurons in the motor cortex in amyotrophic lateral sclerosis.

The motor cortex of eight patients with amyotrophic lateral sclerosis (ALS) and nine control subjects was used in the study. Recent stereological tools, the disector and the rotator method, were applied to the motor cortex of patients with ALS and control subjects to obtain estimates of mean perikaryon volume, mean neuronal nuclear volume, total perikaryon volume and total neuronal nuclear volume. No significant differences were found in any of the estimates. In vivo proton magnetic resonance spectroscopy studies show a decrease in the concentration of neuronal markers. We expected to find changes in perikaryon and/or nuclei neuronal volume because the total neuron number is unchanged in ALS compared with control subjects. However, this was not the case; our results suggest that metabolic changes take place in the motor cortex of ALS patients without these concomitant anatomical changes.

Aged↗

PubMed2005

Measuring morphological and cellular changes in Alzheimer's dementia: a review emphasizing stereology.

From a clinical as well as a neuropathological point of view Alzheimer's disease (AD) has been the focus of intense research for more than three decades. Most studies to identify morphometric correlates with the declining cognitive function in normal aging and AD have employed semi-quantitative methods to assess neuropathological markers such as neurofibrillary tangles, senile plaques, neuronal, or glial cell densities, and neuron sizes. To this end, many cell counting methods have employed two-dimensional designs in single sections, yielding estimates of cell numbers either as neuron densities (number of cell profiles per area) or estimates of the size distribution of neuron profiles in columns vertical to the cortical surface. This approach gives rise to difficulties in interpretation because of the three-dimensional size, shape, and orientation of the counted cells, and the effect of shrinkage artifacts. Modern stereological techniques offer a more rigorous approach for quantifying neuropathological changes associated with aging and degenerative disease. However the stereological studies also suffer from the limitations of high biological variability in AD-type neuropathology, and the relative scarcity of autopsied brains from well-studied non-demented comparison subjects. As a result, the clinicopathological associations between neuropathology and indices of cognitive performance in aging and AD are not yet firmly established. The requirement for the proper description of morphologic neuropathology of AD is clear: any macroscopic or microscopic abnormalities, are subtle and must consequently be demonstrated reproducibly in well-controlled studies. In this review we try to evaluate which, if any, of the contemporary claims for morphometric brain abnormalities in AD can be said to be well established, with special emphasis placed on human stereological post-mortal studies.

Aged↗

PubMed2005

Genetic background determines the size and structure of the endocrine pancreas.

Key parameters of the endocrine pancreas, such as islet number, islet mass, beta-cell mass, and alpha-cell mass, were studied in different strains of inbred mice to investigate the impact of genetic background on the size and structure of the endocrine pancreas. Six mice from each of seven different strains of inbred mice were included in the study. For all parameters investigated, there was a pronounced interstrain variation. ANCOVA showed that only mouse strain was statistically significant as an explanatory parameter for the number of islets. Mouse strain, body weight, and pancreas mass reached statistical significance as explanatory parameters for the islet mass, with mouse strain as the most significant predictor. These data show that genetic background is the most important predictor of both the number of islets and total islet volume. We also conclude that inbred mice could be a valuable resource to identify the genes responsible for the size and structure of the endocrine pancreas.

Analysis of Variance↗

PubMed2004

Myelinated nerve fibres in the subcortical white matter of cerebral hemispheres are preserved in alcoholic subjects.

Previous studies have found that the primary change in the brain of chronic alcoholics is a selective loss of white matter in cerebral hemispheres. It is unknown whether the loss of white matter is due to alcohol-induced degeneration of axons in white matter, and this hypothesis has never been tested. We used a newly developed stereological method to investigate whether the length and diameter of myelinated fibres change in the subcortical white matter of male alcoholic subjects. We found no significant differences between control and alcoholic subjects with respect to the total volume, total length, and mean diameter of myelinated fibres in white matter. Our results do not find any support for the hypothesis that chronic alcoholic subjects may suffer from a degeneration of axons (myelinated fibres) in white matter in cerebral hemispheres.

Alcoholism↗

PubMed2004

Glial cell loss in the anterior cingulate cortex, a subregion of the prefrontal cortex, in subjects with schizophrenia.

OBJECTIVE: Structural deficits in the anterior cingulate cortex such as changes in glial cell and neuron numbers may be part of the anatomical substrate for schizophrenia and need to be investigated. The total number of neurons and glial cells in brains of 12 schizophrenia subjects and 14 comparison subjects were determined in two subdivisions of the prefrontal cortex: Brodmann's area 24, a part of the anterior cingulate cortex, and Brodmann's area 32 in the paracingulate cortex. METHOD: The estimate of the total cell number was obtained by multiplying the volume of the region (estimated by using Cavalieri's point counting method) by the numerical density obtained from optical disectors in the cytoarchitectonically defined areas from the prefrontal cortex. RESULTS: The average total of bilateral glial cells in Brodmann's area 24 was 201 x 10(6 )in subjects with schizophrenia and 302 x 10(6 )in comparison subjects, a statistically significant difference of 33%, whereas there was a nonsignificant difference between the schizophrenia subjects and the comparison subjects in total number of glial cells in Brodmann's area 32. The bilateral average total number of neurons in areas 24 and 32 did not differ significantly between the schizophrenia and comparison subjects. CONCLUSIONS: A selective reduction in glial cells in Brodmann's area 24 (but not in area 32) is seen in brains of subjects with schizophrenia relative to those of comparison subjects. Further investigations of the glial cells, their mutual relationship, and their relationship with neurons are needed to understand the role of specific glial components in this mental disorder.

Adult↗

PubMed2003

Aging of the human cerebellum: a stereological study.

Cerebella from 19 normal Caucasian males, ages 19-84 years, were studied using stereological methods. Cerebellum was divided into four different regions: the anterior and posterior lobe, the vermis, and the flocculonodular lobe. Total volume of the cerebellar cortex and white matter, cerebellar surface area, total Purkinje and granule cell number, and the distribution of the volumes of the Purkinje cells and their nuclei were estimated in all four regions. The global white matter was reduced by 26% with age; the mean volume of the Purkinje cell body was decreased by 33% with no decrease in the volume of the Purkinje cell nuclei. A tendency towards a 16% total cerebellar volume loss was seen without a concomitant neuron loss. No global Purkinje or granule cell loss was detected with age, total Purkinje cell number being 28 x 10(6) (coefficient of variation, CV = 0.16) and total granule cell number 109 x 10(9) (CV = 0.17). However, a significant change was observed with age in the anterior lobe, where a selective 40% loss of both Purkinje and granule cells was found. Furthermore, a 30% loss of volume, mostly due to a cortical volume loss, was recorded in the anterior lobe, which is predominantly involved in motor control.

Adult↗

PubMed2003

Marked loss of myelinated nerve fibers in the human brain with age.

The white matter is the structure of the brain that declines most with age-almost 30%, but little is known about the age-effect on the fibers that constitute the white matter. In the present study, the total length of myelinated fibers was measured with a newly developed stereologic method. Specimens came from 36 normal Danes (18 males and 18 females) with an age ranging between 18 and 93 years. Samples were taken systematically and randomly from the white matter, and the biopsy specimens were randomly rotated before sectioning to avoid bias due to the anisotropic nature of nerve fibers. The fibers were counted at light microscopic level at approximately 10,000x magnification, and the diameter of each counted fiber was measured to get the diameter distribution. Males were found to have a total myelinated fiber length of 176,000 km at the age of 20 and 97,200 km at the age of 80, whereas the total length in females was 149,000 km at the age of 20 and 82,000 km at the age of 80. This finding corresponds to a 10% decrease per decade or a total decrease of 45% from the age of 20 to 80 years, and a sex difference of 16%. The fiber diameter distribution showed that primarily the thinner fibers were lost with a relative preservation of the thicker ones. The marked loss of myelinated nerve fibers with age could explain some of the cognitive decline seen in the elderly.

Adult↗

PubMed2003

Comparison of MR imaging against physical sectioning to estimate the volume of human cerebral compartments.

The purpose of this study was to compare magnetic resonance imaging (MRI) against physical sectioning techniques to estimate the volume of human cerebral hemisphere compartments (cortex, subcortex, and their union, called "total"). The volume of these compartments was estimated postmortem for six human subjects from MRI virtual sections and from physical sections using the Cavalieri design with point counting. Cursory paired t tests revealed no significant differences between the two methods for any of the three compartments considered, although P = 0.06 for the subcortex. A sharper analysis incorporating recent error prediction formulae revealed a significant discrepancy between the two methods in the estimation of subcortex and total volume for three of the specimens. Yet, none of these analyses is adequate to detect possible biases. The incorporation of an explanatory variable, namely hemisphere weight, and the adoption of a specific gravity rho = 1.04 g/cm(3) for the material, enabled us to carry out an allometric analysis for the total compartment which revealed a significant bias of the MRI data. The new error prediction formulae are illustrated by way of example, and their accuracy is checked by a resampling experiment on a data set of 274 MRI sections.

Aged↗

PubMed2003

The changing number of cells in the human fetal forebrain and its subdivisions: a stereological analysis.

The total number of cells--including both neurons and glial cells - was estimated in the neocortical part of the human fetal telencephalon in 22 normal brains within four major developmental zones: the cortical plate/marginal zone, the subplate, the intermediate zone and the ventricular/subventricular zone. The fetal ages ranged from 13 to 41 weeks of gestation. The cellular growth in the human fetal forebrain appears to be two-phased: one rapid, exponential phase from 13 to 20 weeks of gestation and a second and slower phase, which increases linearly, from approximately 22 weeks of gestation to term. From 13 to 20 weeks of gestation the total number of cells increases by a factor of 4.3 from 3 x 10(9) cells to 13 x 10(9) cells at 20 weeks of gestation. From mid-gestation to term, the total cell number increases by a factor of 2.9 to 38 x 10(9) cells in the newborn infant. Studying cellular growth in the normal human fetal brain is important since it may serve as a useful parameter for the assessment of cortical growth in non-invasive and histological studies, and thus improve the analysis of fetal brain disturbances.

Autopsy↗

PubMed2003

The endocrine pancreas in non-diabetic rats after short-term and long-term treatment with the long-acting GLP-1 derivative NN2211.

Glucagon-like peptide 1 (GLP-1) and GLP-1 receptor agonists increase the beta-cell mass in rodent models of type 2 diabetes and enhance the proliferation rate of beta cells in vitro, while the long-term effect in vivo in non-diabetic animals is unknown. We studied the endocrine pancreas in non-diabetic Sprague-Dawley rats after short- and long-term treatment with NN2211, an acetylated long-acting derivative of GLP-1. Four groups of rats (n=6 for each group) received two daily injections with either NN2211 or vehicle for 1 or 6 weeks. NN2211-treated rats displayed a 10% lower body weight after both 1 week (p<0.001) and 6 weeks (p<0.005) of treatment. The mean beta-cell mass in NN2211-treated rats was increased by 19% after 1 week of treatment (p<0.05), but normalized after 6 weeks of treatment. No difference in alpha-cell mass, volume-weighted mean islet volume, or pancreas mass was found after 1 or 6 weeks of treatment. We conclude that NN2211 treatment of non-diabetic rats induces a sustained lower body weight, and an only temporary increase in the beta-cell mass, while the alpha-cell mass and the volume-weighted mean islet volume are unaffected by the treatment.

Animals↗