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J Y Jew

Publications and source records attributed to J Y Jew.

12 recordsLinked to original sources
PubMed1991

Tachykinins in the canine gastroesophageal junction.

Lower esophageal sphincter (LES) effects produced by the mammalian tachykinins were evaluated in anesthetized dogs. The distribution and content of substance P (SP) and neurokinin A (NKA) in the region of the canine gastroesophageal junction was also studied. SP and NKA stimulated a linear dose-dependent contraction of the LES after intra-arterial administration. Neurokinin B (NKB) failed to stimulate an increase in LES pressure (LESP). SP was characterized by an immediate but short-lived contraction followed by a period of relaxation. NKA stimulated a potent LES contraction that was slow in onset but long-lasting. On an equimolar basis, both SP and NKA were approximately 100 times more potent LES stimulants than bethanechol or phenylephrine. Pretreatment with atropine (muscarinic blockade) or tetrodotoxin (neural blockade) inhibited the effect produced by SP. NKA appeared to stimulate LES contraction independent of neural or cholinergic mechanisms. Radioimmunoassay revealed a regional variation in tachykinin content in the gastroesophageal junction. Ganglia, cell bodies, nerve fascicles, and neurites stained specifically for both SP and NKA. The variable effects, potencies, and mechanisms of action observed in this study suggest the presence of specific tachykinin receptor subtypes in the gastroesophageal junction. Both SP and NKA were found to have a broad neural distribution in this region. These findings suggest that the tachykinins may play an important role in neuroregulation of LES smooth muscle.

Animals↗
PubMed1990

Variations in atrioventricular valve innervation in four species of mammals.

In this series of studies, the innervation patterns of whole-mount preparations of bicuspid and tricuspid valves were studied by light microscopy in the mouse, rat, guinea pig, and opossum. The acetylcholinesterase-positive networks of nerve fibers showed many similarities in the basic patterns of valve innervation in all of the species studied, but several interspecies variations were observed. The basal zone of the valve adjacent to the fibromuscular atrioventricular ring displayed the most dense plexus of nerves, with acetylcholinesterase-positive fibers being seen across the width of the valve. In the intermediate zone of the valve, less dense plexuses of nerve fibers were found; and these were more numerous in the cuspal areas and less numerous in the intervening commissural areas. In the distal portions of the valve, nerve networks arborized extensively, with some of their nerve fibers extending toward the chordae tendineae and the free edges of the valve cusps. Only in the guinea pig and opossum did these fibers reach the free margin of the valve cusp, where they either ended directly as free nerve endings or lay parallel to the free edge of the cusp, often running between adjacent chordae tendineae. Although the patterns of innervation were similar in both bicuspid and tricuspid valves, the innervation density of the bicuspid valve was greater than that of the tricuspid valve for each species examined. A distinguishing feature of guinea pig and opossum tricuspid valves was that their chordae tendineae were relatively more prominent and more densely innervated than the bicuspid chordae tendineae. Free nerve endings with no light microscopic evidence of specialization were present throughout the bicuspid and tricuspid valves of all species studied. Some nerve endings in the opossum showed evidence of specialization, with brush-like arborizations leading to presumed free terminals seen chiefly in the distal zone of the valve cusps. Although some general tendencies were apparent, we have demonstrated that interspecies heterogeneity exists in the terminal networks of the atrioventricular valves of mouse, rat, guinea pig, and opossum.

Animals↗
PubMed1989

Collateral sprouting of somatostatin-immunoreactive axons after partial deafferentation of the central nucleus of the rat amygdala.

These experiments utilize a paradigm developed to study plastic responses of peptidergic neurons in a discrete brain area following deafferentation. The central nucleus of the amygdala (CNA) is richly innervated by somatostatin-immunoreactive (SS-I) terminal axons. In the course of preliminary light microscopic (LM) investigations by this laboratory, changes were observed in the density of presumed SS-I terminals in the rat CNA after lesioning the medial input. The LM finding of increased density of presumed SS-I terminals in the CNA at the 10-day post-lesion stage underscored the need for a quantitative electron microscopic (EM) study of the SS-I components, including an evaluation of synaptic events at different survival periods. At the 3-day post-lesion stage, EM examination showed degenerating axons in the lesioned CNA, many already engulfed by astrocytes. None of the degenerating profiles were SS-I, supporting the view that the lesion did not interrupt, to any significant extent, SS-I axons entering the nucleus. EM surveys of the 10-day post-lesion material demonstrated that degenerated profiles had almost completely disappeared. Numbers of SS-I axon terminals, particularly of smaller-sized profiles, were increased by 22% over control value. Synaptic frequency was decreased by 16% below control value. Numbers of SS-I terminals making synapses were increased 3.4% above control value. At the 30-day post-lesion stage, the total number of SS-I terminal axons had increased 86% over controls, whereas the synaptic frequency had decreased by about a third below controls. The absolute number of SS-I terminals engaging in synapses had increased by 24% over controls. The 90-day post-lesion CNA showed a further increase in the number of SS-I axon profiles: 136% over control value. The synapse-to-axon ratio (synaptic frequency) of 27% was similar to that observed for the CNA from the unlesioned side or from unoperated animals. At this stage the number of SS-I synapses had increased by 135% over controls. This model presents many possibilities for studying neuroplasticity, particularly involving peptidergic neurons of the central autonomic nervous system.

Amygdala↗
PubMed1989

The intestine as a model for neuronal plasticity.

This study focuses on establishing the nature and extent of the changes that occur in gastroenteric innervation, specifically the myenteric plexus of the rat ileum, following an injury generated by experimental obstruction. A partial obstruction was accomplished by placing a cuff around the terminal portion of the ileum of the rat. Substantial hypertrophy of the enteric muscle wall occurred after 3-5 weeks. Light microscopic examination of the myenteric plexus revealed changes in the numbers of neuronal perikarya, ganglia and perikarya per ganglia; sizes and shapes of perikarya; and thicknesses of nerve fiber bundles. Using vasoactive intestinal polypeptide (VIP) and substance P light microscopic immunohistochemistry, we observed indications of transmitter accumulation in cell bodies and nerve fibers and reactive, degenerative and regenerative changes in axonal endings. Electron microscopic studies provided evidence for neuroplastic changes, as demonstrated by the appearance of reactive and regenerative, or growth, cones in the myenteric plexus.

Animals↗
PubMed1985

Histofluorescence and ultrastructural observations of small intensely fluorescent (SIF) cells in the superior sympathetic ganglion of the guinea pig.

Amine-containing small intensely fluorescent (SIF) cells are ubiquitous in vertebrate sympathetic ganglia and, in some species, SIF cells have been identified as interneurons. The hypothesis proposed in this study is that SIF cells in superior sympathetic ganglia of the guinea pig function as interneurons, with efferent connections characteristic for the species. Fluorescence (catecholamine) microscopy and 5-hydroxydopamine marker for electron microscopy were used to study SIF cells, their processes and connections in this ganglion. Brightly fluorescent fibers were seen attached to virtually all SIF cells, and were of two types. The first type, single or arranged in cords, interconnected elements of the SIF-cell system; these apparent linkages joined individual SIF cells as well as adjacent clusters. The electron-microscopic evidence for synaptic contacts between SIF cells warrants the claim that integrated action is a presumed function of these elements. The second type of SIF-cell process was generally of greater length. These individual, branching fibers made presumed connections with dendrites of most principal ganglionic neurons. This arrangement suggested by histofluorescence preparations was confirmed by electron microscopy to involve synaptic connections, and the postsynaptic element was shown to be continuous with the perikaryon of the principal ganglionic neuron. Ultrastructural evidence that collections of dense-cored vesicles occur within processes of both principal ganglionic neurons and SIF cells, in proximity to unsheathed portions of plasma membrane, leads to the conclusion that interstitial diffusion of catecholamine from both may occur; the finding of SIF cell processes adjacent to fenestrated blood vessels suggests that catecholamine may also be transported through capillaries.

Animals↗
PubMed1979

Ultrastructural evidence for remodelling in a central noradrenergic pathway following electrolytic lesioning.

Electrolytic lesions were carried out in the medial hypothalamus of adult rats to study remodelling responses in a central noradrenergic pathway, the medial forebrain bundle. Four days, two weeks, 4 weeks and 8 weeks post-lesion, the animals were perfused and processed for correlated fluorescence microscopic (FM) and electron microscopic (EM) study. FM evaluation 4 days post-lesion showed that, compared with control preparations, catecholaminergic fibers became thick, distorted and intensely fluorescent. With increasing survival times the caliber of these fibers became finer and fluorescence intensity was gradually diminished. Some of the small blood vessels in the vicinity of the lesion acquired an intense perivascular fluorescence. Electron microscopic examination of the lesion site 4 days post-lesion disclosed many degenerating axons and increased extracellular space. No increased extracellular space was discerned by 8 weeks post-lesion. After all survival periods greatly enlarged axonal profiles were seen, and these resembled 'growth cones' described in earlier tissue culture, developmental and peripheral nervous system studies.

Adrenergic Fibers↗
PubMed1979

CNS changes in hyperbilirubinemia. Functional implications.

Hyperbilirubinemia is a recognized etiologic factor in motor and hearing disorders associated with cerebral palsy. Its role in more subtle forms of neurological impairment is more controversial. Using a mutant animal model, which develops symptoms and signs closely resembling the human kernicterus syndrome, neurons of hippocampus, cerebral cortex, cochlear nuclei, losuc ceruleus, and olfactory bulb were examined by electron microscopy. Pathological changes, observed in all areas studied, consisted of mitochondrial and endoplasmic enlargement and vacuolation, with glycogen deposition; increased extracellular space; myelin figures; and degenerating changes in nerve terminals. If we make the assumption that pathologic changes in the human infant with neonatal jaundice are similar to changes in the animal model, then the widespread involvement of CNS neurons in all cortical areas examined may well help to explain the syndromes of minimal cerebral dysfunction reported in clinical studies.

Age Factors↗
PubMed1977

Ultrastructural aspects of bilirubin encephalopathy in cochlear nuclei of the Gunn rat.

The cochlear nuclei of homozygous Gunn rats aged 2 days to 7 months were examined. Ultrastructural abnormalities were observed in all age groups studied, including 2 and 4 days old animals. Mitochondrial alterations are amont the earliest manifestations of bilirubin encephalopathy (2 days). In mitochondria of large neurons, vacuoles were found which contained increasing (with age) collections of alpha and beta glycogen particles. Some of the larger 'ex-mitochondrial sacs' appear to have been caught at the point of disruption, with glycogen-filled vacuoles in close proximity. Dilated profiles of rough ER also contained glycogen particles. In the cytoplasm of the same large neurons, elaborate myelin figures surrounded tongues of cytoplasm, vacuoles and degenerative elements. Reconsideration of previous morphological and biochemical observations in the light of the present findings makes it appear very likely that bilirubin primarily affects membrane function, especially in mitochondria.

Animals↗
PubMed1975

An improved method for perfusion fixation of neural tissues for electron microscopy.

A method employing vascular perfusion for improved preservation of biological ultrastructure is described, and its effectiveness demonstrated for mammalian nervous tissues. Following a physiological saline flush into the aorta, hydrogen peroxide and glutaraldehyde in phosphate buffer are perfused. After buffer rinses, tissue blocks are postfixed in osmic acid and potassium ferrocyanide. The success rate is enhanced greatly by close attention to details of perfusion technique. Advantages of the method include more uniform and complete preservation. In particular, superior images of membranous elements, glycogen granules and basal laminar material are achieved. Adjustments in osmolality may render the procedure suitable for nonmammalian forms and other tissues.

Animals↗
PubMedDate not supplied

Neurotensin immunoreactivity in the central nucleus of the rat amygdala: an ultrastructural approach.

Neurotensin (NT) was demonstrated in the central nucleus of the rat amygdala (CNA) using a modification of the avidin-biotin complex immunohistochemical technique. Electron-dense reaction product (particles were 15-25 nm in diameter) was localized in perikarya, dendrites, axons, and axon terminals. It was found also associated with profiles of rough endoplasmic reticulum, mitochondria, microtubules, and small agranular as well as large granular vesicles. In distal dendrites, the reaction product was associated with microtubules, vesicles, and postsynaptic densities. Axon terminals of three types formed synaptic contracts with NT-immunoreactive neurons in the CNA: one was characterized by numerous round or oval agranular vesicles, the second by numerous pleomorphic vesicles, and the third by agranular vesicles that were loosely distributed and pleomorphic. All three types formed symmetric axosomatic and asymmetric axodendritic contacts. NT-immunoreactive axon terminals containing small round agranular vesicles stood out clearly from the intermingling profiles of immunonegative structures. We found numerous glomeruli, each consisting of a central NT-immunoreactive dendrite surrounded by all three types of axon terminals. We observed that some NT-immunoreactive terminals formed symmetric axoaxonal contacts with each other, providing evidence for the presence of local NT-to-NT circuits, whereas many others synapsed with axon terminals devoid of NT immunoreactivity.

Amygdala↗
PubMedDate not supplied

A quantitative histological study of changes in neurons and glia in the Gunn rat brain.

The rostral part of the anterior limb of the anterior commissure (RAL) and the indusium griseum of the brains of Gunn rats and Wistar rats were examined quantitatively to assess the effects of hyperbilirubinaemia on the developing nervous system. The number of glia in the RAL was significantly less in Gunn rats than in the Wistar rats. The number of glia in the indusium griseum was similar in both groups but the Gunn rats showed a decrease of about 20% in the number of neutrons in this region. Myelination appeared to be unaffected and apart from an apparent increase in the number of dense bodies in astrocytes and oligodendrocytes there were no obvious morphological changes in either glia or neurons.

Animals↗