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Biomedical subjects

C B Saper

Publications and source records attributed to C B Saper.

175 records · Page 10Linked to original sources
PubMed1978

Edinger-Westphal nucleus: projections to the brain stem and spinal cord in the cat.

The efferent connections of the Edinger-Westphal (EW) nucleus of the cat have been examined using the autoradiographic anterograde axonal transport technique. Following injections of [3H]amino acids into the EW nucleus, fibers could be traced from this region to a number of sites in the caudal brain stem and spinal cord heretofore not known to receive an afferent input from this nucleus. Two descending pathways have been identified. One pathway travels in the medialmost aspect to the medial longitudinal bundle and terminates in the dorsal accessory olive. The other pathway leaves the nucleus laterally, coursing through the medial tegmentum, and then shifts to a ventrolateral position in the rostral rhombencephalon. Some fibers of this lateral pathway curve dorsally and terminate in the medial parabrachial nucleus. The remainder of this fiber system lies ventral to the spinal trigeminal complex, with some axons terminating in the subtrigeminal nucleus, while other fibers continue ventral to the caudal part of the spinal trigeminal nucleus and appear to terminate in the marginal layer and ventromedial part of this nucleus. Another component of this system terminates between the gracile and medial cuneate nuclei. The main pathways from the EW nucleus to the spinal cord include (1) some fibers which course through the dorsal column nuclei into the ventromedial part of the dorsal columns, and (2) other fibers which continue caudally immediately along the ventrolateral aspect of the spinal trigeminal nucleus and then proceed to the spinal cord in the region between the dorsal horn and the lateral cervical nucleus. These EW fibers appear to terminate mainly in Rexed's lamina I (marginal layer); other fibers, from both tracts appear to terminate in lamina V. There was no evidence for any ascending projections from the EW nucleus. Confirmatory data were obtained from a series of horseradish peroxidase (HRP) experiments, in which EW neurons were retrogradely labeled following injections into the dorsal column nuclei, spinal trigeminal nucleus, inferior olivary nucleus, or spinal cord. These results clearly indicate that the traditional view of the EW nucleus as merely a parasympathetic preganglionic nucleus should be seriously questioned.

Animals↗
PubMed1976

The efferent connections of the ventromedial nucleus of the hypothalamus of the rat.

The efferent connections of the ventromedial nucleus of the hypothalamus (VMH) of the rat have been examined using the autoradiographic method. Following injections of small amounts (0.4-2.0 muCi) of tritium labeled amino acids, fibers from the VMH can be traced forward through the periventricular region, the medial hypothalamus and the medial forebrain bundle to the preoptic and thalamic periventricular nuclei, to the medial and lateral preoptic areas, to the bed nucleus of the stria terminalis and to the ventral part of the lateral septum. Some labeled axons continue through the bed nucleus of the stria terminalis into the stria itself, and hence to the amygdala, where they join other fibers which follow a ventral amygdalopetal route from the lateral hypothalamic area and ventral supraoptic commissure. These fibers terminate in the dorsal part of the medial amygdaloid nucleus and in the capsule of the central nucleus. A lesser number of rostrally directed fibers from the VMH crosses the midline in the ventral supraoptic commissure and contributes a sparse projection to the contralateral amygdala. Descending fibers from the VMH take three routes: (i) through the medial hypothalamus and medial forebrain bundle; (ii) through the periventricular region; and (iii) bilaterally through the ventral supraoptic commissure. These three pathways are interconnected by labeled fibers so that it is not possible to precisely identify their respective terminations. However, the periventricular fibers seem to project primarily to the posterior hypothalamic area and central gray, as far caudally as the anterior pole of the locus coeruleus, while the medial hypothalamic and medial forebrain bundle fibers apparently terminate mainly in the capsule of the mammillary complex, in the supramammillary nucleus and in the ventral tegmental area. The ventral supraoptic commissure fibers leave the hypothalamus closely applied to the medial edges of the two optic tracts. After giving off their contributions to the amygdala, they continue caudally until they cross the dorsal edge of the cerebral peduncle to enter the zona incerta. Some fibers probably terminate here, but others continue caudally to end in the dentral tegmental fields, and particularly in the peripeduncular nucleus. Within the hypothalamus, the VMH appears to project extensively to the surrounding nuclei. However, we have not been able to find evidence for a projection from the VMH to the median eminence. Isotope injections which differentially label the dorsomedial or the ventrolateral parts of the VMH have shown that most of the long connections (to the septum, amygdala, central tegmental fields and locus coeruleus) originate in the ventrolateral VMH, and there is also some evidence for a topographic organization within the projections of this subdivision of the nucleus.

Animals↗
PubMed1976

Midbrain, diencephalic and cortical relationships of the basal nucleus of Meynert and associated structures in primates.

The structure and connectivity of the basal nucleus of Meynert, the substantia innominata in which it lies, and certain related areas have been examined in New World and Old World Monkeys, using retrograde and anterograde axonal transport methods. Experiments using the retrograde, horseradish peroxidase method confirm the observations of Kievet and Kuypers ('75) that the basal nucleus and substantia innominata project directly, heavily and with a somewhat crude topography upon the neocortex. Experiments involving the anterograde, autoradiographic method show that the basal nucleus and substantia innominata form part of a complex pathway that links them together with the lateral hypothalamus, certain parts of the amygdala and the peripeduncular nucleus of the midbrain. The peripeduncular nucleus is often regarded as a part of the central auditory pathway; it gives rise to a fiber bundle of considerable size that ascends on the dorsal surface of the ipsilateral optic tract and terminates ultimately in the lateral hypothalamic area of both sides. As well as distributing fibers to the basal nucleus, substantia innominata and lateral hypothalamus, this pathway provides a heavy projection to a cytoarchitectonically distinct posterior part of the lateral nucleus of the amygdala, the medial and intercalated nuclei of the amygdala and a less dense projection to the bed nucleus of the stria terminalis. Certain parts of the hypothalamus and possibly the preoptic areas give rise to a complementary descending pathway that distributes fibers to the ipsilateral basal nucleus, substantia innominata and amygdala, and ends in the peripeduncular nuclei of both sides. Decussating fibers in both the ascending and descending pathways cross in the ventral supraoptic commissure. It is concluded that the basal nucleus should include most of the aggregated and unaggregated large cells that lie in the substantia innominata and which in places intrude upon the preoptic regions and the nucleus of the diagnonal band of Broca. Together, these may form a complex that receives inputs from a variety of brainstem sources, and projects widely and diffusely upon all cortical structures of the telencephalon.

Amygdala↗
PubMedDate not supplied

The value of alternative morphological approaches to Alzheimer's disease.

Coleman and Flood find the morphometric approach of limited value in differentiating the pathological changes in Alzheimer's disease from normal aging. However, other morphological approaches, particularly studies of the chemical neuroanatomy of Alzheimer's disease, are proving to be highly informative. Coleman and Flood's conclusion, that morphological examination of post-mortem brain is of limited value, is not justified.

Alzheimer Disease↗
PubMedDate not supplied

Pathological changes in frontal cortex from biopsy to autopsy in Alzheimer's disease.

We evaluated the change in density of total senile plaques, plaque subtypes, and neurofibrillary tangles, from biopsy to autopsy in left frontal cortical sections from four patients with clinically typical Alzheimer's disease (AD). Comparisons were made on sections stained with modified Bielschowsky and Thioflavin S. In two cases, comparisons were also made on tissue stained with a monoclonal Alz-50 antibody and an antiserum to A beta (beta-amyloid protein). Despite a marked decline in mental status over several years of follow-up clinical evaluations, there was no consistent significant change in numerical density of plaques or tangles among the four cases. However, we did find fewer primitive plaques in the autopsy specimens. These results from longitudinally evaluated persons with typical AD suggest that although plaques and tangles may serve as adequate markers of the presence of AD, their numerical density within a single neocortical region may not reflect dementia severity. This conclusion supports the results of recent cross-sectional studies on the progression of pathology among persons with AD.

Alzheimer Disease↗
PubMedDate not supplied

Ultrastructure of neurofibrillary tangles in the cerebral cortex of sheep.

Recently, we reported that neurofibrillary tangles (NFTs) of the Alzheimer type develop in the cerebral cortex of aged sheep (Ovis aries). In the current study, we utilized light and electron microscopic immunocytochemistry to describe in greater detail the characteristics of sheep NFTs during early stages of neurofibrillary degeneration. We investigated neurons that were stained using the monoclonal antibody Alz-50 and that contained relatively small numbers of paired helical filaments (PHFs). Serially cut ultrathin sections were evaluated to take maximal advantage of ultrastructural resolution. At the light microscope level, we observed preferential localization of Alz-50 immunoreactive accumulations at dendritic branch points in early NFTs. A similar staining pattern was observed using the monoclonal antibody AT8 which recognizes a phosphorylated epitope on tau. Ultrastructurally, we found that Alz-50 staining at dendritic branch points was associated with clusters of ribosomes. The focal deposition of phosphorylated tau proteins at dendritic branch points may indicate a link between the initial stages of neurofibrillary pathology and specific cytoskeletal alterations that involve dendritic remodeling. Neurons that contained relatively small numbers of PHFs appeared otherwise healthy with regard to their cytoskeleton and organelles.

Aging↗
PubMedDate not supplied

Inhibition of the firing of vasopressin neurons by atriopeptin.

Atriopeptin, the atrial natriuretic peptide, is a circulating hormone that is released from the atria of mammalian hearts in response to volume expansion and acts upon the kidneys, adrenal glands and vasculature to regulate fluid and electrolyte homeostasis. Atriopeptin is also present in the brain of the rat. Atriopeptin immunoreactive cell bodies and fibres are found in many areas known to be involved in the central regulation of the cardiovascular system, suggesting that it may be a neuromediator in the central control of fluid and electrolyte balance. The paraventricular nucleus of the hypothalamus, which contains the cell bodies of neurons that secrete vasopressin from the posterior pituitary gland, receives a dense innervation from atriopeptin-like immunoreactive fibres. We have studied the effect of atriopeptin on the electrical activity of single neurons in the paraventricular nucleus of anaesthetized rats and found that atriopeptin is a potent inhibitor of putative vasopressin neurons. Atriopeptin, which has systemic actions that oppose those of vasopressin, may act as a neuromodulator in the brain to prevent vasopressin secretion.

Action Potentials↗