Persistence of a Groundwater Contaminant Plume after Hydraulic Source Containment at a Chlorinated-Solvent Contaminated Site.

The objective of this study was to characterize the behavior of a groundwater contaminant (trichloroethene) plume after implementation of a source-containment operation at a site in Arizona. The plume resides in a quasi three-layer system comprising a sand/gravel unit bounded on the top and bottom by relatively thick silty clayey layers. The system was monitored for 60 months beginning at start-up in 2007 to measure the change in contaminant concentrations within the plume, the change in plume area, the mass of contaminant removed, and the integrated contaminant mass discharge. Concentrations of trichloroethene in groundwater pumped from the plume extraction wells have declined significantly over the course of operation, as have concentrations for groundwater sampled from 40 monitoring wells located within the plume. The total contaminant mass discharge associated with operation of the plume extraction wells peaked at 0.23 kg/d, decreased significantly within one year, and thereafter began an asymptotic decline to a current value of approximately 0.03 kg/d. Despite an 87% reduction in contaminant mass and a comparable 87% reduction in contaminant mass discharge for the plume, the spatial area encompassed by the plume has decreased by only approximately 50%. This is much less than would be anticipated based on ideal flushing and mass-removal behavior. Simulations produced with a simplified 3-D numerical model matched reasonably well to the measured data. The results of the study suggest that permeability heterogeneity, back diffusion, hydraulic factors associated with the specific well field system, and residual discharge from the source zone are all contributing to the observed persistence of the plume, as well as the asymptotic behavior currently observed for mass removal and for the reduction in contaminant mass discharge.

Humic acid metal cation interaction studied by spectromicroscopy techniques in combination with quantum chemical calculations.

Humic acids (HA) have a high binding capacity towards traces of toxic metal cations, thus affecting their transport in aquatic systems. Eu(III)-HA aggregates are studied by synchrotron-based scanning transmission X-ray microscopy (STXM) at the carbon K-edge and laser scanning luminescence microscopy (LSLM) at the (5)D(0) --> (7)F(1,2) fluorescence emission lines. Both methods provide the necessary spatial resolution in the sub-micrometre range to resolve characteristic aggregate morphologies: optically dense zones embedded in a matrix of less dense material in STXM images correspond to areas with increased Eu(III) luminescence yield in the LSLM micrographs. In the C 1s-NEXAFS of metal-loaded polyacrylic acid (PAA), used as a HA model compound, a distinct complexation effect is identified. This effect is similar to trends observed in the dense fraction of HA/metal cation aggregates. The strongest complexation effect is observed for the Zr(IV)-HA/PAA system. This effect is confirmed by quantum chemical calculations performed at the ab initio level for model complexes with different metal centres and complex geometries. Without the high spatial resolution of STXM and LSLM and without the combination of molecular modelling with experimental results, the different zones indicating a ;pseudo'-phase separation into strong complexing domains and weaker complexing domains of HA would never have been identified. This type of strategy can be used to study metal interaction with other organic material.

Interaction of latex colloids with mineral surfaces and Grimsel granodiorite.

Bentonite clay is considered as possible backfill material for nuclear waste repositories in crystalline rock. The same material may also be a source of clay colloids, which may act as carriers for actinide ions possibly released from the repository. Depending on the geochemical parameters, these colloids may be retained by interaction with mineral surfaces of the host rock. In the present study interaction of carboxylated fluorescent latex colloids, used as a model for bentonite colloids, with natural Grimsel granodiorite and some of its component minerals is studied by fluorescence microscopy and SEM/EDX. The experiments are carried out by varying the pH from 2-10. Strong adsorption is observed at pH values close to or below the points of zero charge (pHpzc) of the mineral surfaces. The influence of Eu(III), used as a chemical homologue for trivalent actinide ions, on colloid adsorption is investigated. Depending on mineral phase and pH, a significant increase of colloid adsorption is observed in the presence of Eu(III).

The surface chemistry of sapphire-c: A literature review and a study on various factors influencing its IEP.

A wide range of isoelectric points (IEPs) has been reported in the literature for sapphire-c (α-alumina), also referred to as basal plane, (001) or (0001), single crystals. Interestingly, the available data suggest that the variation of IEPs is comparable to the range of IEPs encountered for particles, although single crystals should be much better defined in terms of surface structure. One explanation for the range of IEPs might be the obvious danger of contaminating the small surface areas of single crystal samples while exposing them to comparatively large solution reservoirs. Literature suggests that factors like origin of the sample, sample treatment or the method of investigation all have an influence on the surfaces and it is difficult to clearly separate the respective, individual effects. In the present study, we investigate cause-effect relationships to better understand the individual effects. The reference IEP of our samples is between 4 and 4.5. High temperature treatment tends to decrease the IEP of sapphire-c as does UV treatment. Increasing the initial miscut (i.e. the divergence from the expected orientation of the crystal) tends to increase the IEP as does plasma cleaning, which can be understood assuming that the surfaces have become less hydrophobic due to the presence of more and/or larger steps with increasing miscut or due to amorphisation of the surface caused by plasma cleaning. Pre-treatment at very high pH caused an increase in the IEP. Surface treatments that led to IEPs different from the stable value of reference samples typically resulted in surfaces that were strongly affected by subsequent exposure to water. The streaming potential data appear to relax to the reference sample behavior after a period of time of water exposure. Combination of the zeta-potential measurements with AFM investigations support the idea that atomically smooth surfaces exhibit lower IEPs, while rougher surfaces (roughness on the order of nanometers) result in higher IEPs compared to reference samples. Two supplementary investigations resulted in either surprising or ambiguous results. On very rough surfaces (roughness on the order of micrometers) the IEP lowered compared to the reference sample with nanometer-scale roughness and transient behavior of the rough surfaces was observed. Furthermore, differences in the IEP as obtained from streaming potential and static colloid adhesion measurements may suggest that hydrodynamics play a role in streaming potential experiments. We finally relate surface diffraction data from previous studies to possible interpretations of our electrokinetic data to corroborate the presence of a water film that can explain the low IEP. Calculations show that the surface diffraction data are in line with the presence of a water film, however, they do not allow to unambiguously resolve critical features of this film which might explain the observed surface chemical characteristics like the dangling OH-bond reported in sum frequency generation studies. A broad literature review on properties of related surfaces shows that the presence of such water films could in many cases affect the interfacial properties. Persistence or not of the water film can be crucial. The presence of the water film can in principle affect important processes like ice-nucleation, wetting behavior, electric charging, etc.

Molecular and functional analysis of hyperpolarization-activated pacemaker channels in the hippocampus after entorhinal cortex lesion.

Differential display of hippocampal tissue after entorhinal cortex lesion (ECL) revealed decreases in mRNA encoding the neuronal hyperpolarization-activated, cyclic nucleotide-gated channel HCN1. In situ hybridization confirmed that hippocampal transcripts of HCN1, but not HCN2/3/4, are down-regulated after ECL. Expression recovered at approximately 21 days after lesion (dal). Immunohistochemistry demonstrated a corresponding regulation of HCN1 protein expression in CA1-CA3 dendrites, hilar mossy cells and interneurons, and granule cells. Patch-clamp recordings in the early phase after lesion from mossy cells and hilar interneurons revealed an increase in the fast time constant of current activation and a profound negative shift in voltage activation of Ih. Whereas current activation recovered at 30 dal, the voltage activation remained hyperpolarized in mossy cells and hilar interneurons. Granule cells, however, were devoid of any detectable somatic Ih currents. Hence, denervation of the hippocampus decreases HCN1 and concomitantly the Ih activity in hilar neurons, and the recovery of h-current activation kinetics occurs parallel to postlesion sprouting.

Reninlike enzymes in human vasculature.

The present study was designed to identify angiotensin I (Ang I)-forming angiotensinogenases in human extrarenal vasculature and to examine the theory of Jiménez Días on their stimulation in essential hypertension. Vascular sections obtained intraoperatively from 14 normotensive and 16 hypertensive patients undergoing corrective surgery, 68 umbilical cord blood vessels from parturient women, tissue samples from nine explanted hearts, and serum from anephric and healthy individuals were investigated. Ang I-forming angiotensinogenase activities were determined enzyme-kinetically by using Ang I radioimmunoassay and purified sheep or human angiotensinogens. Three nonrenin Ang I-forming angiotensinogenases (pH optima of 4.0, 5.1, and 6.1) were identified in extrarenal vasculature, in cardiac tissues, and in plasma. Highest specific activities of nonrenin Ang I-forming angiotensinogenase (in nanograms Ang I per gram times hour; mean +/- SD) were found in cardiac tissue (2,821 +/- 497, n = 9), followed by carotid artery intima (1,448 +/- 982, n = 10), arteries (1,307 +/- 736, n = 18), and umbilical cord arteries (135 +/- 55, n = 35). Extrarenal arterial Ang I-forming angiotensinogenases were linearly correlated with those of local angiotensin converting enzyme and plasma renin activity. In essential hypertension, extrarenal arterial Ang I-forming angiotensinogenases were scattered, but not generally stimulated. The data obtained indicate the existence of nonrenin Ang I-forming angiotensinogenases in human extrarenal vasculature, in kidney, and in plasma. The postulate of stimulation of extrarenal arterial Ang I-forming angiotensinogenases in essential hypertension cannot be supported. Similar to the classification of plasma renin activity, a classification of Ang I-forming angiotensinogenase activity is proposed, consisting of patients with essential hypertension divided into subgroups exhibiting high, normal, or low vascular Ang I-forming angiotensinogenase activities.

Parvalbumin-containing nonpyramidal neurons in intracortical transplants of rat hippocampal and neocortical tissue: a light and electron microscopic immunocytochemical study.

Previous immunocytochemical studies have shown that GABAergic nonpyramidal neurons of the rat hippocampus survive in intracerebral transplants. However, information is still lacking about the dendritic organization and the input synapses of these cells as well as their capacity to express the calcium-binding protein parvalbumin (PARV) under transplant conditions. In the present study, a monoclonal antibody against PARV was used to examine the dendritic morphology and the synaptic organization of parvalbumin-containing GABAergic neurons in hippocampal and dentate transplants. In addition, parvalbumin-containing nonpyramidal neurons were studied in neocortical transplants to compare the differentiation of grafted allocortical and neocortical nonpyramidal neurons. Tissue blocks of hippocampus and fascia dentata and of the parietal neocortex were taken from late embryonic rats (E 21 and E 16, respectively) and were transplanted into a cavity in the somatosensory cortex of young adult rats. After 3.5 or 7 months survival, the recipient brains were fixed by perfusion and immunostained for PARV. As in the hippocampal formation in situ, PARV-containing neurons in the hippocampal transplants were observed within and in the vicinity of the pyramidal and granule cell layer. In neocortical transplants, PARV-immunoreactive cells were distributed in all parts of the transplant with dendrites extending in various directions. In both hippocampal and neocortical transplants, immunoreactive dendrites were smooth and displayed the characteristic regular varicosities known from in situ studies of these cells. Numerous unlabeled terminals as well as a few immunoreactive boutons established synapses on the immunoreactive dendrites. PARV-positive terminals formed the typical pericellular baskets around the immunonegative cell bodies of pyramidal neurons and granule cells in the transplants. They established symmetric synapses with cell bodies and proximal dendrites. Synapses on axon initial segments were absent or rare. Our results demonstrate that allocortical as well as neocortical nonpyramidal neurons transplanted to the neocortex of adult recipients survive transplantation, express the calcium-binding protein parvalbumin, and develop a cell-specific morphology.

Development of cholinergic and GABAergic neurons in the rat medial septum: effect of target removal in early postnatal development.

During normal development of the nervous system, the target fields influence the survival and differentiation of projection neurons, but the factors regulating this interaction remain obscure. In the present study, we have raised the question whether the target region is essential for the postnatal development and maintenance of two different types of central projection neurons, cholinergic and GABAergic septohippocampal cells. In early postnatal rats (P5, P10), the hippocampus was eliminated by unilateral intrahippocampal injections of the excitotoxin N-methyl-D-aspartate. After a long survival time (at P70), we have immunostained serial sections of the septal region with antibodies against choline acetyltransferase (ChAT), the acetylcholine-synthesizing enzyme, or the calcium-binding protein parvalbumin (PARV) which is known to be contained in GABAergic septohippocampal neurons. In the medial septum ipsilateral to the lesioned side, about 60% of ChAT-immunoreactive neurons and 62% of PARV-immunoreactive neurons were found in adulthood even after complete elimination of the hippocampus. Some immunoreactive cells appeared heavily shrunken, but electron microscopic analysis revealed ultrastructural characteristics typical for medial septal neurons obtained from controls. Our results indicate that target elimination during development affected both types of projection cells, although only the cholinergic cells are known to be responsive to target-derived factors.

Development of cholinergic and GABAergic neurons in the rat medial septum: different onset of choline acetyltransferase and glutamate decarboxylase mRNA expression.

In the present study, we have investigated the developmental expression of the transmitter-synthesizing enzymes choline acetyltransferase (ChAT) and glutamate decarboxylase (GAD) in rat medial septal neurons by using in situ hybridization histochemistry. In addition, we have employed immunostaining for ChAT and the calcium-binding protein parvalbumin, known to be contained in septohippocampal GABAergic neurons. A large number of GAD67 mRNA-expressing neurons were already observed in the septal complex on embryonic day (E) 17, the earliest time point studied. During later developmental stages, there was mainly an increase in the intensity of labeling. Neurons expressing ChAT mRNA were first recognized at E 20, and their number slowly increased during postnatal development of the septal region. The adult pattern of ChAT mRNA-expressing neurons was observed around postnatal day (P) 16. By using a monoclonal ChAT antibody, the first immunoreactive cells were not seen before P 8. Similarly, the first weakly parvalbumin-immunoreactive neurons were seen in the septal complex by the end of the 1st postnatal week. These results indicate that in situ hybridization histochemistry may be an adequate method to monitor the different development of transmitter biosynthesis in cholinergic and GABAergic septal neurons. Moreover, the late onset of ChAT mRNA expression would be compatible with a role of target-derived factors for the differentiation of the cholinergic phenotype.

Twenty-four-hour blood pressure profile and blood pressure responses to head-up tilt tests in Parkinson's disease and multiple system atrophy.

OBJECTIVE: To investigate the 24 h blood pressure profile in patients with Parkinson's disease with intact autonomic function or with autonomic failure and patients with multiple system atrophy (MSA), and to assess whether these patients exhibit posture-related variations in blood pressure. PATIENTS AND METHODS: We studied 24 patients with Parkinson's disease (11 with autonomic failure) and 13 patients with MSA (all with autonomic failure). Autonomic failure was determined by autonomic tests. An oscillometric recorder was used for ambulatory blood pressure monitoring. Tilt-table tests were performed with a head-up tilt position of 60 degrees. RESULTS: An alteration in the normal 24 h blood pressure profile was observed in 82% of Parkinson's disease patients with autonomic failure and in 85% of those with multiple system atrophy, but not in the patients with intact autonomic function. Head-up tilt tests revealed a significantly higher supine blood pressure in Parkinson's disease patients with autonomic failure and in those with MSA than in Parkinson's disease patients with intact autonomic function. Tilting resulted in a marked fall in blood pressure in patients with MSA; in Parkinson's disease patients with autonomic failure, the fall was comparatively slighter. CONCLUSIONS: We conclude that autonomic failure contributes to the alterations in the day-night blood pressure profile that may possibly be ascribed to postural dysregulation of blood pressure. We hypothesize that nocturnal hypertension is a risk factor in the development of additional cerebrovascular disease in patients with Parkinson's disease or MSA who are affected by autonomic failure.

Localization of two major GABA(A) receptor subunits in the dentate gyrus of the rat and cell type-specific up-regulation following entorhinal cortex lesion.

GABA(A) receptor subunits show a specific regional distribution in the CNS during development and in the adult animal. In the hippocampal formation, individual subsets of GABAergic interneurons are highly immunoreactive for the alpha1-subunit, whereas granule and pyramidal cells show a strong expression of the alpha2-subunit. Using confocal microscopy and digital image analysis, we demonstrate that in the dentate gyrus the alpha1-subunit immunolabeling appears in differently sized clusters. The large clusters, which are confined to dendrites of interneurons, show no alpha2 labeling, whereas the smaller ones coincide with alpha2-subunit-positive clusters. In the molecular layer, the clusters of both alpha-subunits co-localize with the anchoring protein gephyrin. In the granule cell layer and hilus, we found alpha1- and alpha2-subunit-positive clusters which were devoid of gephyrin labeling. Lesions of the medial entorhinal cortex led to the deafferentation of dendrites in the middle molecular layer of the dentate gyrus. This resulted in a significantly increased concentration of alpha2-subunit-positive clusters. We also observed an increase of alpha1-subunit immunolabeling in the deafferented area. We found no change in the co-localization between alpha1 and alpha2, and no significant change in the number of large alpha1-positive clusters along individual dendritic segments of interneurons. In a previous study, we demonstrated that calbindin-immunoreactive dendrites of granule cells revealed a significant increase in gephyrin immunoreactivity following lesion, whereas parvalbumin-positive dendrites showed no such alterations. The predominant localization of small gephyrin clusters in dendrites of granule cells, which was also described in this study, leads to the conclusion that the increase of the alpha2-subunit-positive clusters, demonstrated in the present study, indicates that, following entorhinal cortex lesion, new GABAergic synapses may be formed and that they contact predominantly granule cell dendrites.

Perforant path lesion induces up-regulation of stathmin messenger RNA, but not SCG10 messenger RNA, in the adult rat hippocampus.

In this study, we performed in situ hybridization analysis of the expression pattern of two growth-associated proteins, stathmin and SCG10, in the hippocampus after unilateral lesion of the perforant pathway, the main excitatory input from the entorhinal cortex to the hippocampus. Stathmin is one of the major neural-enriched cytosolic phosphoproteins and a potential target of cyclic-AMP-dependent kinases [Jin L. W. et al. (1996) Neurobiol. Aging 17, 331-341; Leighton I. A. et al. (1993) Molec. Cell Biochem. 127/128, 151-156]. Three days after the lesion, stathmin messenger RNA was up-regulated ipsilaterally in the hilus, in the granule cell layer of the dentate gyrus and in the pyramidal cell layer of the CA1 region. Simultaneously, the hilar region of the contralateral dentate gyrus showed an increased stathmin messenger RNA expression. This altered expression pattern was observed until 15 days after lesion. Stathmin messenger RNA expression returned to a normal level until 21 days after lesion in all regions analysed. SCG10, a membrane-bound neuronal growth-associated protein belonging to the SCG10/stathmin gene family, did not show any alteration of messenger RNA expression after perforant path lesion. The temporal changes of stathmin messenger RNA expression in the ipsilateral hippocampus correspond well to the process of reactive synaptogenesis. The enhanced messenger RNA expression in the hilar region of the contralateral dentate gyrus might suggest a role in neurite elongation, since this region is the origin of commissural fibres involved in the sprouting response in the deafferented hippocampus. The present study provides evidence that the induction of specific growth-associated proteins is differentially regulated in the hippocampus.

Cholecystokinin expression after hippocampal deafferentiation: molecular evidence revealed by differential display-reverse transcription-polymerase chain reaction.

The cortical information flow via the perforant path represents a major excitatory projection to the hippocampus. Lesioning this projection leads to massive degeneration and subsequently to reorganization in its termination zones as well as in primary non-affected subfields of the hippocampus. The molecular mechanisms and factors which are involved in the postlesional events are poorly defined. Using a differential display reverse transcription-polymerase chain reaction (DDRT-PCR) strategy, we located one band which occurred only in control hippocampus lanes and almost disappeared in the lanes of lesioned hippocampi. By sequencing, we identified the corresponding gene as cholecystokinin (CCK). Northern blot analysis confirmed a decreased transcription of CCK after lesion. In situ hybridization analysis was performed for localization and quantification of altered CCK transcription. We noted a significant downregulation of CCK transcription in the hippocampus (20%) and in the contralateral cortex (12%) 1-day after lesion (dal) and an increased signal in the ipsilateral cortex (10.5%). This pattern was altered, showing upregulation of CCK mRNA expression, reaching its highest level of 70% above control levels at 5 dal. In the hippocampus, the control level was reached again at 21 dal, whereas the cortex reached the control level at 10 dal. In comparison, the mRNA transcripts of the receptors CCK(A) and CCK(B) remained unchanged. Since CCK-containing neurons are involved in the modulation of pyramidal and granule cell excitability, our data indicate a time course correlation between CCK mRNA expression and postlesional axonal sprouting response in the hippocampus.

Usefulness of simultaneous ambulatory electrocardiographic and blood pressure monitoring in detecting myocardial ischemia in patients > 70 years of age with systemic hypertension.

Ischemic-type ST-segment depression is frequently observed in younger hypertensive patients. To assess the frequency of ST-segment depression in elderly hypertensive patients and to determine the influence of heart rate (HR) and blood pressure (BP) on the episodes of transient myocardial ischemia, ambulatory electrocardiographic and BP monitoring was simultaneously performed in 41 untreated hypertensive patients > 70 years of age (mean age 79 +/- 6 years; office BP > or = 160/95 mm Hg). A total of 66 episodes of significant ST-segment depression (> or = 0.1 mV, duration > or = 1 minute, interval > or = 1 minute) could be demonstrated in 15 patients (37%); 26 patients (63%) had no ST-segment changes. The 2 groups did not differ in age, gender, office or ambulatory BP, diurnal BP profile, concomitant diseases, ventricular arrhythmias, or in left ventricular (LV) mass or function. In 11 patients with ST-segment depression (73%), an increase in HR of > 15% preceded the episodes of ST-segment depression; 2 of these patients (13%) had an additional increase in BP of > 20/10 mm Hg. The extent of ST-segment depression was correlated significantly to BP, HR and HR x systolic BP product during the ischemic events, to office BP, and to LV mass. In conclusion, transient myocardial ischemia is a frequent phenomenon in elderly hypertensive patients with and without LV hypertrophy. Whereas most episodes of ischemia are preceded by an increase in HR, the extent of ST-segment depression is dependent on HR, BP and LV mass.

Angiotensin I-forming angiotensinogenases in extrarenal vasculature and in the kidney.

The intention of this study was to characterize angiotensin I-forming angiotensinogenases (AIFAs) in rat extrarenal arterial walls and to clarify whether these enzymes are also present in the kidney. A further aim was to identify AIFAs in human vasculature and to establish whether they are affected in essential hypertension. Sprague-Dawley rats and vascular sections of patients undergoing corrective surgery were studied. Enzyme kinetic assays were performed using angiotensin I radioimmunoassay and purified natural angiotensinogens. Fast protein liquid chromatography was employed for biochemical characterization. A series of AIFAs with various isoelectric points, molecular weights and pH optima was detected in rat extrarenal vascular and, with differing distributions of enzyme activities, in renal tissues. In extrarenal arteries the main form of renal renin was present with a relatively low activity only. AIFAs were also demonstrable in human extrarenal vasculature and behaved like plasma renin in essential hypertension. The results indicate the existence of an intrinsic human vascular RAS in extrarenal (and renal) arteries. Extrarenal arterial AIFAs are not generally stimulated in essential hypertensives, as previously postulated.

Entorhinal cortex lesion studied with the novel dye fluoro-jade.

We used the fluorescent dye Fluoro-Jade, capable of selectively staining degenerating neurons and their processes, in order to analyze degenerative effects of transecting the hippocampus from its main input, the entorhinal cortex in vivo and in organotypical hippocampal slice culture. Degenerating fibers stained with Fluoro-Jade were present as early as 1 day postlesion in the outer molecular layer of the dentate gyrus and could be detected up to 30 days postlesion. However, the intensity of the Fluoro-Jade staining in the outer molecular layer faded from postlesional day 20 onward. Punctate staining, various cells and neural processes became visible in this area suggesting that degenerating processes were phagocytosed by microglial cells or astrocytes. We conclude that Fluoro-Jade is an early and sensitive marker for studying degenerating neurites in the hippocampal system.

Survival and transmitter expression of rat cholinergic medial septal neurons despite removal of hippocampus in the early postnatal period.

It has been shown that target-derived neurotrophins are not necessary for the survival of septohippocampal cholinergic neurons in adult rats. In this study, we have removed the hippocampus in early postnatal rats by unilateral excitotoxic N-methyl-D-aspartate lesions at postnatal days 5, 10 and 20. At postnatal day 70, numerous cholinergic neurons (60% of controls) were present in the medial septum on the lesioned side. This suggests that there is only a limited influence of target-derived neurotrophic factors to these cells also in development.

Morphological alterations of hippocampal pyramidal neurons heterotopically transplanted into the somatosensory cortex of adult rats: a quantitative Golgi study.

A characteristic feature of hippocampal organization is the laminated termination of extrinsic and intrinsic afferents. At present, it is not known to what extent these layer-specific fiber projections modulate the development and final shape of the dendritic arbor of hippocampal target neurons. In the present study, pieces of late embryonic (E18) rat hippocampus were transplanted heterotopically into a cavity in the somatosensory cortex of 6-8 week-old recipient rats. Here, the transplanted neurons differentiated and survived up to several months in the absence of their specific extrinsic afferents. Moreover, tracing of transplant connections with the carbocyanine dye DiI revealed only a limited projection between the transplant and the host neocortex. Golgi-impregnated transplants were used to analyze the postsynaptic structures (dendrites and spines) of hippocampal pyramidal cells quantitatively. Compared with controls, the transplanted pyramidal neurons showed a significant reduction of apical primary dendrites and basal dendritic branches, i.e. of peripheral dendritic portions that originate farther from the soma. In contrast, the number of basal primary dendrites originating directly from the perikaryon was enhanced. Spine density on the main apical dendritic shaft was significantly lower in all peripheral dendritic segments in transplanted neurons. We conclude from our results that the absence of layer-specific extrinsic afferents that normally terminate on peripheral parts of the dendritic arbor of hippocampal pyramidal neurons caused a reduction of these peripheral dendrites and spines. In contrast, the increase of dendrites and spines near the cell body might be induced by intrinsic fibers that normally terminate on these proximal dendritic portions and are known to sprout under transplant conditions.

The transentorhinal cortex of the African green monkey: a combined light- and electron-microscopic study of calcium-binding protein containing neurons.

The transentorhinal cortex (TEC) is a primate-specific transition zone between the entorhinal allocortex and the temporal isocortex. Neurons in the lamina pre-alpha of TEC are known to be the first to develop intraneuronal changes in the course of Alzheimer's disease. In order to shed light on this important feature, we studied as yet unknown morphological and neurochemical characteristics of the TEC of the African green monkey (Cercopithecus aethiops sabaeus). Using light- and electron-microscopic immunocytochemistry, the distribution and morphology of neurons containing calcium-binding proteins were described and compared with those in the adjacent cortices. Light-microscopic analysis revealed that parvalbumin-containing neurons were distributed in all cortical layers. Calbindin-containing cells were fewer but also present in each layer. Calretinin-containing neurons were largely confined to the upper layers of the TEC. All three types of neuron showed pyramidal-like, multipolar and bipolar shapes; their dendrites were smooth or beaded. Ultrastructural studies revealed immunopositive somata with infolded nuclei and large amounts of cytoplasm. The somata were only sparsely innervated by symmetric synapses. Immunopositive dendrites were almost exclusively covered with immunonegative axon terminals establishing symmetric and asymmetric synapses. Immunopositive terminals established symmetric contacts with immunonegative dendrites and somata. Only occasionally, could synaptic contacts between immunopositive pre- and postsynaptic structures be observed. The comparison of neurons in the TEC and adjacent cortices revealed no striking differences. In summary, the morphological and neurochemical characteristics of TEC neurons as analyzed in our study do not provide an explanation for the early onset of neurodegenerative changes in the TEC.

Severe spontaneous carotid artery dissection and multiple aneurysmal dilatations. A case report.

Spontaneous cervical artery dissections or arterial aneurysms associated with deficiencies of alpha(1)-antitrypsin (alpha(1)-AT) or other inhibitors of proteolytic enzymes have occasionally been reported. However, a coexistence of severe spontaneous internal carotid artery dissection and multiple aneurysmal dilatations associated with alpha(1)-AT phenotype M1S have not yet been presented; herein the authors describe such a patient. In order to avoid the risks associated with intraarterial angiography in a patient in whom an underlying arteriopathy is suspected, only noninvasive techniques were employed. This case demonstrates that magnetic resonance imaging combined with magnetic resonance angiography is a valuable noninvasive method for use in diagnosis and follow-up of carotid artery dissection.