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.

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.

Distribution of the receptor-anchoring protein gephyrin in the rat dentate gyrus and changes following entorhinal cortex lesion

We analyzed the distribution of the receptor-anchoring protein gephyrin in the normal and deafferented rat dentate gyrus to investigate whether the expression of this postsynaptic protein is altered in response to the formation of new synaptic contacts. Confocal microscopy and digital image analysis revealed that in normal dentate gyrus immunolabeling was most prominent in the outer molecular layer and decreased successively in the direction of the granule cell layer. Simultaneous immunolabeling for gephyrin and cell-specific markers showed that granule cells and parvalbumin-positive interneurons express gephyrin. Large, intensely stained, gephyrin-positive clusters were distributed along distinct dendrites, and most of them were positive for parvalbumin. Calbindin-immunostained dendrites were associated with smaller, gephyrin-positive clusters. Lesion of the medial entorhinal cortex leads to deafferentiation of the middle molecular layer which resulted in an increased gephyrin immunoreactivity. These changes were due to a significantly increased concentration of the very small gephyrin-positive clusters. Parvalbumin-positive dendrites did not display any increase in co-localizing gephyrin-positive structures. The altered immunolabeling pattern persisted until 12 weeks after lesion, a time when the process of synaptic reorganization is complete. Our findings suggest that synaptogenesis following deafferentiation results in a cell-specific redistribution of gephyrin immunoreactivity at specific inhibitory synapses.

Outgrowth-promoting molecules in the adult hippocampus after perforant path lesion

Lesion-induced neuronal plasticity in the adult central nervous system of higher vertebrates appears to be controlled by region- and layer-specific molecules. In this study we demonstrate that membrane-bound hippocampal outgrowth-promoting molecules, as present during the development of the entorhino-hippocampal system and absent or masked in the adult hippocampus, appear 10 days after transection of the perforant pathway. We used an outgrowth preference assay to analyse the outgrowth preference of axons from postnatal entorhinal explants on alternating membrane lanes obtained from hippocampus deafferented from its entorhinal input taken 4, 10, 20, 30 and 80 days post-lesion and from adult control hippocampus. Neurites from the entorhinal cortex preferred to extend axons on hippocampal membranes disconnected from their entorhinal input for 10 days in comparison with membranes obtained from unlesioned adult animals. Membranes obtained from hippocampi disconnected from their entorhinal input for 10 days were equally as attractive for growing entorhinal cortex (EC) axons as membranes from early postnatal hippocampi. Further analysis of membrane properties in an outgrowth length assay showed that entorhinal axons extended significantly longer on stripes of lesioned hippocampal membranes in comparison with unlesioned hippocampal membranes. This effect was most prominent 10 days after lesion, a time point at which axonal sprouting and reactive synaptogenesis are at their peak. Phospholipase treatment of membranes obtained from unlesioned hippocampi of adult animals strongly promoted the outgrowth length of entorhinal axons on these membranes but did not affect their outgrowth preference for deafferented hippocampal membranes. Our results indicate that membrane-bound outgrowth-promoting molecules are reactivated in the adult hippocampus following transection of the perforant pathway, and that neonatal entorhinal axons are able to respond to these molecules. These findings support the hypothesis of a temporal accessibility of membrane-bound factors governing the layer-specific sprouting of remaining axons following perforant path lesion in vivo.

Up-regulation of the metabotropic glutamate receptor mGluR4 in hippocampal neurons with reduced seizure vulnerability

Selective hippocampal cell loss and altered neurotransmitter receptor expression have been proposed as pathogenic mechanisms in the development of chronic mesial temporal lobe epilepsy (TLE). Studies in animal models point to metabotropic glutamate receptors (mGluRs) as modulators of hippocampal epileptogenesis. In addition, mGluRs may constitute specific targets for the development of novel anticonvulsive drugs. As mGluR4 represents an inhibitory class III mGluR associated with the reduction of intracellular cyclic AMP levels and calcium influx, we have analyzed the regional and cellular expression of mGluR4 in surgical hippocampal specimens obtained from patients with TLE by using immunohistochemistry and in situ hybridization. Although the hippocampi of control specimens (n = 11) were almost devoid of mGluR4 immunolabeling, all TLE specimens (n = 35) showed a striking up-regulation of mGluR4 immunoreactivity, in particular within the dentate gyrus. Immunoelectron microscopy localized the receptor protein to the periphery of presynaptic and postsynaptic membranes. In situ hybridization revealed increased transcript levels of mGluR4 in dentate granule cells and residual CA4 neurons of TLE specimens compared with controls. Our results suggest a potential role of mGluR4 in counteracting excitatory hippocampal activity and in modulating seizure-associated vulnerability of hippocampal neurons. These data may also provide a basis for pharmacological studies of mGluR4 agonists as potential novel drugs in the treatment of TLE.

Myelin does not influence the choice behaviour of entorhinal axons but strongly inhibits their outgrowth length in vitro

Myelin is crucial for the stabilization of the entorhinohippocampal projection during late development and is a non-permissive substrate for regrowing axons after lesion in the adult brain. We used two in vitro assays to analyse the impact of myelin on rat entorhinohippocampal projection neurons. A stripe assay was used to study the impact of myelin on the choice behaviour of axons from the entorhinal cortex (EC). Given a choice between alternating hippocampal membrane lanes from developmental stages ranging from early postnatal to adult, EC axons preferred to extend on early postnatal hippocampal membranes. Neither the neutralization of myelin-associated factors by a specific antibody (IN-1) nor the separation of myelin from membranes interfered with the axons' choice behaviour. The entorhinal axons showed no preference in the membrane combination of adult and myelin-free adult hippocampal membranes. These stripe assay experiments demonstrate that support for EC axon choice in the developing hippocampus is maturation-dependent and is not influenced by myelin. The application of IN-1 in the outgrowth assay and the separation of myelin from membranes, enhanced elongation of outgrowing entorhinal axons on adult hippocampal membranes, whereas a control antibody did not. This shows that myelin-associated factors have a strong inhibitory effect on the outgrowth length of entorhinal axons. In conclusion, we suggest that axonal elongation in the entorhinohippocampal system during development is strongly influenced by myelin-associated growth inhibition factors and that specific target finding of entorhinal axons is regulated by a different mechanism.

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.

Cardiovascular and renin responses to head-up tilt tests in parkinsonism

OBJECTIVES

We investigated cardiovascular and renin responses to head-up tilt tests in patients with Parkinson's disease (PD), multiple system atrophy (MSA), and in controls to determine variables for the assignment of parkinsonism to the potential underlying neurologic condition.

PATIENTS AND METHODS

Sequential changes in sympathetic-mediated circulatory variables such as heart rate, blood pressure, and plasma renin concentration during head-up tilt tests were studied in 14 patients with PD and 11 patients with MSA. Twelve subjects with normal autonomic functions were studied as controls.

RESULTS

Head-up tilt resulted in significant differences in blood pressure and heart rate responses between PD, MSA, and controls. The baseline plasma renin concentration was significantly lower in MSA than in controls. Twenty min head-up tilt revealed significant differences in plasma renin concentration between PD, MSA, and controls.

CONCLUSION

We conclude that investigating sequential changes in mean arterial blood pressure, heart rate, and plasma renin concentration during head-up tilt test can potentially support differential diagnosis of PD and MSA.

[Neurologic and psychiatric symptoms of legionella infection. Case report and overview of the clinical spectrum]

Legionella is a frequent etiologic agent in the development of both nosocomial and community acquired pneumonias. Involvement of the nervous system is common in Legionella infections. We present a case of Legionnaires' disease which illustrates distinctive neurologic findings including delirium and cerebellar dysfunction. Furthermore, this paper reviews the neurological and psychiatric features of 609 Legionella infected patients with involvement of the nervous system. The most common signs were disorientation (58%), headache (52.4%), and somnolence (39.7%). Less frequent or rare were: cerebellar dysfunction (11.2%), hallucinations (8.4%), agitation or stupor (4.1%), affective disorders (3.1%), peripheral neuropathy (2.8%), pyramidal disturbances (2.1%), memory loss (1.6%), seizures (1.5%), cranial nerve palsies (1.5%), incontinence (0.7%), and extrapyramidal disturbances (0.3%). Cranial CT scans, cerebrospinal fluid findings, and nerve and muscle biopsies were usually unremarkable. Neuropathologic examinations failed to demonstrate specific characteristics. Hyponatremia and serum CPK level elevation were present in up to 89% and 50% of patients, respectively. Prognosis of disturbances of the nervous system was mainly good. We conclude that in the presence of definite neurological findings, pulmonary infection, hyponatremia, and CPK elevation Legionella infection should be considered.

Cardiac field effects on the EEG

The electrical field of the heart propagates throughout the entire body and causes changes in the surface potentials on the scalp that are superimposed on brain electric signals. When heart cycle-related EEG averaging is performed, e.g. in order to measure heart cycle-related brain potentials, the effects of the cardiac electrical field result in a high-amplitude artifact in the surface potentials. The topographic and temporal distributions of the cardiac field artifact were measured in 9 normal subjects. In addition, the effects of head-turning on the field were investigated. The electrocardiac artifact is most prominent during the QRS complex and during the T wave of the heart cycle. In both cases it is distinctly asymmetrical in relation to the hemispheres. A comparison of the scalp potentials and a computed vector ECG showed the 3-dimensional nature of the artifact. Non-computational strategies for the handling of the ECG artifact are discussed. A proper separation of the effects of the cardiac electrical field from heart cycle-related brain potentials is a prerequisite for the study of heart cycle-coordinated brain potentials.

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.

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.

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.

Felodipine or hydrochlorothiazide/triamterene for treatment of hypertension in the elderly: effects on blood pressure, hypertensive heart disease, metabolic and hormonal parameters

The aim of the study was to compare the antihypertensive efficacy of either felodipine or the diuretic combination hydrochlorothiazide/triamterene in a group (n = 65) of elderly (> or = 70 years) hypertensives (office blood pressure > or = 160/95 mmHg) with special regard to ambulatory blood pressure monitoring, hypertensive heart disease and metabolic parameters. This was a randomized, double-blind study with a treatment period of 6 months. Reduction of office and 24-hr ambulatory blood pressure was comparable with both treatment regimens; after 6 months. 18 of 29 patients in the felodipine group (62%) and 20 of 27 patients in the diuretic group (74%; p = 0.4) were controlled. While episodes of ischemic type ST-segment depression were significantly reduced in the felodipine group (from 49 to 9 episodes), there was no significant change in the diuretic group (from 24 to 21 episodes). Both regimens decreased left ventricular wall thickness, but the decline in left ventricular muscle mass index was significant only for felodipine. Felodipine did not induce any change in metabolic or hormonal parameters; the diuretic combination significantly increased serum creatinine, uric acid, plasma renin activity, and plasma prorenin. Thus, the antihypertensive efficacy of felodipine and the diuretic combination was comparable in elderly hypertensives; only felodipine, however, improved parameters of hypertensive heart disease and showed a neutral metabolic and hormonal profile.

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.

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.

"White coat" hypertension and alerting reaction in elderly and very elderly hypertensive patients

"White coat" hypertension can be demonstrated in 20-25% of younger patients with mild-to-moderate hypertension. In a population of 50 untreated hypertensive patients > or = 70 years (mean age 79 +/- 6 years, office blood pressure > or = 160 mmHg systolic and > or = 95 mmHg diastolic) ambulatory blood pressure monitoring, ECG and echocardiography were performed to assess the frequency of "white coat" hypertension and the alerting reaction ("white coat" effect). "White coat" hypertension was diagnosed, if mean daytime ambulatory blood pressure was < or = 146/87 mmHg (taken as upper "normal" limit), "definite" hypertension, if > 146/87 mmHg. Nine patients (18%) were classified as "white coat", 28(56%) as "definite" hypertensives, 13(26%) as an "intermediate" group. There were no differences in gender, weight, concomitant diseases, pre-study treatment, and systolic or diastolic left ventricular function between the groups. Patients with "white coat" hypertension showed lower office blood pressure (178 +/- 13/98 +/- 3 vs 201 +/- 19/104 +/- 7 mmHg; p < 0.004), lower left ventricular mass index (131 +/- 9 vs 139 +/- 26 g/m2, p < 0.5), no left ventricular hypertrophy (ECG-criteria; p < 0.05), a more pronounced alerting reaction (39 +/- 13/22 +/- 5 vs 27 +/- 17/8 +/- 9; p < 0.01) and no correlation between office blood pressure and left ventricular mass compared to the "definite" hypertension group. The total group showed an average alerting reaction of 30 +/- 19/12 +/- 8 mmHg. It is concluded that "white coat" hypertension and an alerting reaction can be demonstrated in untreated elderly and very elderly hypertensive patients. Patients with "white coat" hypertension are characterized by a milder degree of hypertension, less cardiac target organ damage and a more pronounced alerting reaction. The prognostic significance of "white coat" hypertension in the elderly needs to be reevaluated in a larger population.

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.

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.

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.