Showing papers by "Patrick R. Hof published in 1993"

Posterior cortical atrophy in Alzheimer's disease: analysis of a new case and re-evaluation of a historical report.

Abstract: Disturbances of visual function are not uncommon in Alzheimer's disease and several cases with complex impairment of visuospatial abilities have been described. For instance, posterior cortical atrophy has been demonstrated in cases displaying Balint's syn-drome as the first symptom of the dementing illness. Such cases showed very high lesion counts in the occipital cortex, as well as in visual association regions in the posterior parietal and posterior cingulate cortex, whereas the prefrontal cortex was consistently less severely involved than usually observed in Alzheimer's disease. This suggests that the distribution of the lesions had been shifted to specific elements of the visual system. In the present study; we report the quantitative analysis of a new case of Alzheimer's disease with possible Balint's syndrome and re-evaluate a case originally described in 1945. The distribution of lesions in these two cases parallels previous observations of Alzheimer's disease cases with early visual impairment. Both cases displayed very high densities of neurofibrillary tangles and senile plaques in the primary visual cortex, secondary visual cortex, visual association areas of the dorsal occipital and posterior parietal lobe and in the posterior cingulate cortex, whereas the prefrontal and inferior temporal regions were comparatively less affected. These cases may define clinical subgroups of Alzheimer's disease and suggest that the breakdown of corticocortical projections that is known to occur in dementia may involve select components of specific functional systems in certain cases. In particular, path-ways that subserve motion detection and visuospatial analysis appear to be dramatically affected in these cases presenting with Balint's syndrome. Thus, Alzheimer's disease may be a more heterogeneous disorder than previously thought, and refined neuropsychological testing as well as detailed neuropathological evaluation may be of value to detect possible clinical variants of this dementing conditon.

Calcium-binding Protein-containing Neuronal Populations in Mammalian Visual Cortex: A Comparative Study in Whales, Insectivores, Bats, Rodents, and Primates

Abstract: This study is focused on comparative analysis of gamma-aminobutyric acid-positive (GABAergic) neuronal populations in primary visual cortex of totally aquatic toothed whales and select terrestrial mammals with different evolutionary histories and various ecological adaptations. The distribution of neuronal populations containing the calcium-binding proteins calbindin and parvalbumin, which are recognized markers for the GABAergic neurons in cerebral cortex, is compared in five species of toothed whales and in representatives (one species each) of insectivores, bats, rodents, and primates. Computerized image analysis has shown that overall quantitative characteristics of GABAergic cortical neurons in toothed whales are similar to those in other mammalian orders. Thus, GABA-positive neurons represent 26% of the total population of cortical neurons in the visual cortex of whales. Some 97% of GABA-positive cells contain calcium-binding proteins, which is numerically similar to these parameters found in primates and other mammals. On the other hand, the typology and laminar distribution of calcium-binding protein-containing neurons in the primary visual cortex of five whale species (Delphinapterus leucas, Globicephala melaena, Phocoena phocoena, Stenella coeruleoalba, and Tursiops truncatus) differ significantly from those of primates (Macaca mulatta) and rodents (Rattus rattus) and are similar to those found in insectivorous bats (Eptesicus fuscus) and hedgehogs (Erinaceus europaeus). In whales, bats, and hedgehogs a significant concentration of calbindin-positive, vertically oriented bipolar and bitufted neurons was found in layers I, II, and IIIc/V with their axons arranged in a three-dimensional network. In primates and rodents they are distributed evenly across all cortical layers and are predominantly multipolar or bitufted neurons found in all cortical layers with their axons oriented along the vertical axis of the cortical plate. The parvalbumin-positive neurons in all mammalian species, including toothed whales, are represented by variously sized multipolar non-pyramidal cells. As opposed to all other mammalian species, the major concentrations of parvalbumin-positive neurons in whales are found in layers IIIc/V and VI, whereas in other cortical layers there are only scattered parvalbumin-positive neurons.(ABSTRACT TRUNCATED AT 400 WORDS)

Quantitative immunohistochemical analysis of the distribution of neurofibrillary tangles and senile plaques in the cerebral cortex of nonagenarians and centenarians.

Abstract: To investigate the neuropathological differences between normal aging and senile dementia of the Alzheimer type (SDAT) in very old people and to see how they compare with a younger population of demented elderly people, we performed an immunohistochemical quantitative analysis of the topography of senile plaques and neurofibrillary tangles in a series of 31 elderly patients aged from 96 to 102 years According to the medical records, two groups were considered: 7 patients presenting with clinically documented SDAT and 24 patients with no or very mild cognitive impairment The densities of senile plaques were comparable in both groups Extensive neurofibrillary tangle formation was restricted to the CA1 hippocampal field of demented subjects, whereas the superior frontal cortex showed rare neurofibrillary tangles, independently of the clinical diagnosis These results indicate an absence of direct correlation between the number of senile plaques and the clinical manifestation of SDAT Furthermore, they suggest that the dementing process may involve different cortical structures in nonagenarians and centenarians than in younger demented individuals where a widespread cortical involvement is generally observed Thus, the neurofibrillary tangle density in the CA1 field may be critical for the neuropathological diagnosis of SDAT in this particular group of very old patients

Monoaminergic Innervation of Cingulate Cortex

Abstract: As early as 1885 Bristowe recognized that damage to the cingulate gyrus resulted in neurological symptoms including impairment of cognitive function, emotional lability, depression, and loss of awareness. In his classic article, Papez (1937) commented that “the cingulate gyrus is the seat of dynamic vigilance by which emotional experiences are endowed with an emotional consciousness” and that damage to the cingulate gyrus results in a “loss of emotive dynamics.”

Calcium-Binding Proteins Define Subpopulations of Interneurons in Cingulate Cortex

Abstract: Calcium-binding proteins are intracellular calcium acceptors which belong to two different families: the EF-hand proteins and the annexins. Annexins are characterized by proteins that bind calcium in the presence of phospholipid-containing membranes. The EF-hand proteins, which is the topic of this review, consist of proteins showing a general structural principle in the calcium-binding domain called the EF-hand (Kretsinger, 1981). They are composed of a stretch of amino acids having a helix-loop-helix structure. The EF-hand family of calcium-binding proteins contains approximately 30 to 40 different proteins (most of them calcium-modulated), of which several are found in the central nervous system. The EF-hand proteins may function either as “triggers, ” starting a cascade of reactions, or as calcium “buffers, ” decreasing the free cytoplasmic concentration of this ion (Dalgarno et al., 1984). The prototype of a trigger protein is the ubiquitous calmodulin that activates at least 20 different enzymes. The buffer proteins represent a more passive system responsible for decreasing the amplitude of calcium signals.

Noradrenergic innervation of the hypothalamus of rhesus monkeys: Distribution of dopamine‐β‐hydroxylase immunoreactive fibers and quantitative analysis of varicosities in the paraventricular nucleus

Abstract: The distribution of noradrenergic processes within the hypothalamus of rhesus monkeys (Macaca mulatta) was examined by immunohistochemistry with an antibody against dopamine-beta-hydroxylase. The results revealed that the pattern of dopamine-beta-hydroxylase immunoreactivity varied systematically throughout the rhesus monkey hypothalamus. Extremely high densities of dopamine-beta-hydroxylase-immunoreactive processes were observed in the paraventricular and supraoptic nuclei, while relatively lower levels were found in the arcuate and dorsomedial nuclei and in the medial preoptic, perifornical, and suprachiasmatic areas. Moderate levels of dopamine-beta-hydroxylase immunoreactivity were found throughout the lateral hypothalamic area and in the internal lamina of the median eminence. Very few immunoreactive processes were found in the ventromedial nucleus or in the mammillary complex. Other midline diencephalic structures were found to have high densities of dopamine-beta-hydroxylase immunoreactivity, including the paraventricular nucleus of the thalamus and a discrete subregion of nucleus reuniens, the magnocellular subfascicular nucleus. A moderate density of dopamine-beta-hydroxylase immunoreactive processes were found in the rhomboid nucleus and zona incerta whereas little dopamine-beta-hydroxylase immunoreactivity was found in the fields of Forel, nucleus reuniens, or subthalamic nucleus. The differential distribution of dopamine-beta-hydroxylase-immunoreactive processes may reflect a potential role of norepinephrine as a regulator of a variety of functions associated with the nuclei that are most heavily innervated, e.g., neuroendocrine release from the paraventricular and supraoptic nuclei, and gonadotropin release from the medial preoptic area and mediobasal hypothalamus. Additionally, quantitative analysis of dopamine-beta-hydroxylase-immunoreactive varicosities was performed on a laser scanning microscope in both magnocellular and parvicellular regions of the paraventricular nucleus of the hypothalamus. The methodology employed in this study allowed for the high resolution of immunoreactive profiles through the volume of tissue being analyzed, and was more accurate than conventional light microscopy in terms of varicosity quantification. Quantitatively, a significant difference in the density of dopamine-beta-hydroxylase-immunoreactive varicosities was found between magnocellular and parvicellular regions, suggesting that parvicellular neurons received a denser noradrenergic input. These differential patterns may reflect an important functional role for norepinephrine in the regulation of anterior pituitary secretion through the hypothalamic-pituitary-adrenal stress axis.