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D S Knight

Publications and source records attributed to D S Knight.

At least 37 records · Page 2Linked to original sources
PubMed1988

A simple method for combining HRP-TMB histochemistry with tritiated thymidine autoradiography on the same tissue section.

In order to determine the sequence of development of various types of spinal neurons defined by their projection, we have developed a method for combining tritiated thymidine autoradiography for birthdate determination, with the demonstration of retrogradely transported horseradish peroxidase (HRP) using tetramethylbenzidine (TMB) as the chromogen. Because of its greater sensitivity, TMB is the chromogen of choice for the demonstration of HRP. However, the HRP-TMB reaction product is unstable and completely destroyed when the tissue is processed for autoradiography. The present study describes the use of osmium tetroxide as a postreaction stabilizing agent which preserves the HRP-TMB reaction product in the form of a dark brown precipitate which is not destroyed when the tissue is subsequently processed for autoradiography. Background levels of autoradiographs stabilized with the osmium procedure are extremely low.

Animals↗
PubMed1987

Classification of aberrant primary afferents in the substantia gelatinosa of the rat following neonatal capsaicin treatment.

Administration of capsaicin to newborn rats results in a loss of a large percentage of primary afferent C fibers many of which terminate in the substantia gelatinosa (SG). Using the Golgi silver impregnation technique, the present study shows that the loss of C fibers results in an invasion of aberrant myelinated primary afferents in the SG by 10 days after birth. The aberrant afferents, identified on the basis of their distinctive collateral arborizations, are derived from hair follicles and slowly adapting type I mechanoreceptors.

Animals↗
PubMed1987

Vasoactive intestinal peptide-immunoreactive nerves in the rat kidney.

An indirect immunohistochemical method in which an avidin-biotinylated horseradish peroxidase complex is bound to the secondary antibody was used to visualize vasoactive intestinal peptide-immunoreactive (VIPI) nerves in the rat kidney. Rats were perfused with 4% paraformaldehyde or 2% paraformaldehyde + 0.15% picric acid in 0.1 M phosphate buffer, then transferred to the buffer. After 24-48 hours, the kidneys were sectioned with a Vibratome at 200 or 300 micron and incubated in the primary antiserum for 18 hours at room temperature. A sparse plexus of VIPI nerves innervates the rat renal calyx. Some VIPI nerves innervate interlobar arteries and each succeeding segment of the arterial tree including afferent arterioles, but most innervate arcuate and interlobular arteries. VIPI axons do not innervate each arcuate artery or each interlobular branch of an arcuate artery with equal density. Although some axons follow each interlobular branch, most form a dense plexus on only one or two branches. Therefore, most VIPI nerves in the rat kidney innervate a restricted segment of the renal arterial tree. These nerves may be efferent and may selectively dilate arcuate and smaller arteries, or they may be afferent and may sense local changes in mechanical or chemical parameters.

Animals↗
PubMed1987

Substance P-immunoreactive nerves in the rat kidney.

An indirect immunohistochemical method in which an avidin-biotinylated horseradish peroxidase complex is bound to the secondary antibody was used to visualize substance P-immunoreactive (SPI) nerves in the rat kidney. Rats were perfused with 2% paraformaldehyde + 0.15% picric acid in 0.1 M phosphate buffer, then transferred to the buffer. After 24-48 h, the kidneys were sectioned with a Vibratome at 200 or 300 micron and incubated in the primary antiserum for 18 h at room temperature. A dense plexus of SPI nerves innervates the rat renal calyx. A small proportion of intrarenal SPI axons innervates interlobular arteries and afferent arterioles, but most perivascular SPI axons terminate on interlobar and arcuate arteries. The densest plexuses are located on segments of interlobar arteries near the hilus of the kidney. Some of these axons probably are nociceptive; others may be chemo- or baroreceptive.

Animals↗
PubMed1984

An ultrastructural study of intrarenal catecholamine-containing elements.

Histochemical visualization of catecholamines and electron microscopy in the same tissue sample were used to localize and study catecholamine-containing nerve enlargements or swellings in male Wistar and Sprague-Dawley rat kidneys. These swellings lie in the perivascular nerve plexuses of arcuate and interlobular arteries near the points of origin of arterioles, and are composed of modified axons and associated Schwann cells. Transverse sections of the enlarged nerves reveal that individual axons are also enlarged, have processes or folds and make contact with one another. The axonal enlargements contain small mitochondria with a dense matrix and clusters of small vesicles, many of which are associated with an organelle composed of parallel cisternae of smooth membranes.

Animals↗
PubMed1983

A model of an intraprostatic vas deferens in the rat.

The study of the effect of hormones in seminal fluid upon prostate tissue is hampered by the lack of a suitable model. Such a model is described in this paper, and its possible usefulness is discussed. The vas deferens of the rat is moved from its normal position into a surgical incision into the ventral prostate. Squamous metaplasia of epithelium in prostatic acini at early stages is replaced by cuboidal epithelium. At later stages, normal-appearing glandular epithelium is seen as close as 50 micrometers to the vas deferens. The structure of the vas deferens is not affected.

Animals↗
PubMed1981

A light and electron microscopic study of the innervation of pulmonary arteries in the cat.

Nerve terminal-smooth muscle relationships were studied in pulmonary arteries of the cat using 5-hydroxydopamine to help differentiate adrenergic and nonadrenergic terminals. There was a periarterial plexus of nerves in the walls of pulmonary arteries that extended into the lung to innervate even small arteries having a single layer of smooth muscle cells. Adrenergic nerves surrounded all arteries and extended into the tunica media of the large arteries. There were also apparent cholinergic nerves around the pulmonary arteries, although this was confirmed by electron microscopy for medium- and small-sized arteries only. The relationships of nerve terminals to smooth muscle cells in pulmonary arteries suggest that release of norepinephrine by adrenergic terminals can produce both decreased compliance and increased resistance in the pulmonary vascular bed, and that acetylcholine released by cholinergic terminals may act directly on vascular smooth muscle or on adrenergic terminals to modulate release of norepinephrine. These results suggest that both sympathetic and parasympathetic nerves may have a regulatory role in the pulmonary circulation.

Adrenergic Fibers↗
PubMed1981

Innervation of intrapulmonary airway smooth muscle of the dog, monkey and baboon.

Intrapulmonary airways of the dog, monkey and baboon were examined with the electron microscope. Differentiation of adrenergic and nonadrenergic nerves was facilitated by the use of 5-hydroxydopamine which was infused into the pulmonary arteries (500 microgram/min for 30-45 min). In all species, nerves composed mainly of unmyelinated axons lay external to the muscularis and in the muscularis between bundles of smooth muscle cells. Nerves composed of varicose unmyelinated axons that ran parallel with the smooth muscle bundles contributed fibers that surrounded and entered these bundles. Most of the varicosities associated with airway smooth muscle were cholinergic, and longitudinal sections of the muscle bundles revealed elongate profiles of these varicosities. Most cholinergic varicosities in dog, monkey and baboon airway smooth muscle had no special morphologic relationships to the surrounding smooth muscle cells. Other cholinergic varicosities in the primates lay in depressions of the sarcolemmae. Some of these varicosities were apposed to the sarcolemmae and formed neuromuscular clefts devoid of electron-dense material. There were some adrenergic varicosities near bronchial smooth muscle cells of all species studied. Another type of nerve varicosity, which was present in all species contained many large dense-core vesicles 90-120 nm in diameter and some small, agranular vesicles 40-60 nm in diameter.

Adrenergic Fibers↗
PubMed1981

Reversal of the normal pattern of renal choline metabolism during uremia in rats.

Chronic uremia was produced in rats by removal of 85% of renal mass. 3 and 8 weeks later in the remnant kidneys the normal ratio of phosphorylcholine/betaine production from 14C-choline (1:2) was reversed. Phosphorylcholine production rose from 24.0 +/- 1.4 to 45.6 +/- 4.5 pmol/min/mg protein (p less than 0.001), and betaine production fell from 51.0 +/- 1.4 to 23.1 +/- 4.5 pmol/min/mg protein (p less than 0.001). This reversed pattern is also found in fetal and neonatal kidneys and during renal compensatory growth.

Animals↗
PubMed1981

Pulmonary vasodilator responses to catecholamines and sympathetic nerve stimulation in the cat. Evidence that vascular beta-2 adrenoreceptors are innervated.

We investigated the effects of catecholamines and sympathetic nerve stimulation in the feline pulmonary vascular bed under conditions of controlled pulmonary blood flow. Norepinephrine and nerve stimulation caused dose- and stimulus frequency-dependent increases in pulmonary vascular resistance. However, when pulmonary vascular tone was enhanced and alpha receptors blocked, norepinephrine and nerve stimulation caused dose- and frequency-dependent decreases in pulmonary vascular resistance. The decreases in pulmonary vascular resistance were blocked with propranolol and were of greater magnitude than were constrictor responses observed under basal conditions. Vasodilator responses to nerve stimulation were not modified by atropine. Epinephrine and isoproterenol had marked vasodilator activity in the pulmonary vascular bed when pulmonary vascular tone was elevated. When alpha receptors were blocked, isoproterenol and epinephrine had similar vasodilator activity, and when beta receptors were blocked, epinephrine and norepinephrine had marked vasoconstrictor activity. Selective beta-1 receptors antagonists had little effect on vasodilator responses to isoproterenol, whereas responses to this substance were blocked by propranolol. These results suggest that presence of alpha-and beta-2 adrenoreceptors in the feline pulmonary vascular bed and that both types of adrenergic receptors are innervated by the sympathetic nervous system.

Animals↗
PubMed1980

An inexpensive vibrating microtome for sectioning fixed tissue.

A tissue sectioner which uses a vibrating razor blade and a simple mechanism for the elevation of the tissue can be constructed for less than fifty dollars. The razor blade in fixed to the vibrator of a hair clipper and a nut and bolt serve as the tissue advance mechanism. A metal disc attached to the nut is used for the stage. The tissue advance mechanism is placed inside a machined teflon cylinder which provides a smooth surface upon which the razor assembly is moved. Fixed tissue may be sectioned uniformly at a thickness of 50 micrometer or more. This device has the advantages of portability, rapidity of sectioning, and inexpensive construction.

Microtomy↗
PubMed1980

A light and electron microscopic study of feline intrapulmonary ganglia.

Fluorescence microscopy and transmission electron microscopy were used to study peribronchial ganglia of cats. An osmiophilic substance that is selectively taken up into the synaptic vesicles of adrenergic nerves (5-hydroxydopamine) was used to help differentiate adrenergic and non-adrenergic terminals. Peribronchial ganglion cells show no catecholamine fluorescence and are unaffected by 5-hydroxy-dopamine. There are three types of efferent terminals in the ganglia: cholinergic terminals, terminals with small agranular round and flat vesicles and terminals that contain large dense-core vesicles as well as small vesicles and tubules that take up 5-hydroxydopamine. Clusters of SIF cells are associated with some peribronchial ganglia. It is suggested that peribronchial ganglion cells integrate synaptic input from two or three types of nerve terminals and may also be affected by catecholamines released into the bronchial vascular system by SIF cells.

Animals↗
PubMed1979

Visualization of intrarenal catecholamine-containing elements: fluorescence histochemistry and electron microscopy.

Fluorescence histochemistry and electron microscopy were used to study catecholamine-containing elements in rat and cat kidneys. There were fluorescent nerve plexuses associated with the arterial system of the renal cortex from which nerves extended into the medulla forming dense networks in the vascular bundles of the outer part of the medulla. Also, there were small cells found singly and in clusters which emitted the blue fluorescence characteristic of catecholamine-containing cells. These cells were associated with the periarterial nerve plexuses and were frequently encountered in the cat medullary vascular bundles. Electron microscopy of the cat renal medulla revealed processes with the structure of typical adrenergic terminals and other processes that resemble small intensely fluorescent (SIF) cell processes.

Adrenergic Fibers↗
PubMed1976

Influence of 5- and 6-hydroxydopamine on adrenergic transmission and nerve terminal morphology in the canine pulmonary vascular bed.

We studied the effects of 5- and 6-hydroxydopamine on adrenergic neurotransmission, fluorescence histochemistry, and nerve terminal ultrastructure in the canine pulmonary vascular bed. Fluorescence histochemistry on stretched preparations and sections of intrapulmonary artery and vein demonstrated that these vessels are well supplied with adrenergic nerves electron microscopy revealed adrenergic terminals in the adventitia and outer third of the media in the artery, but only in the adventitia in the vein. Adrenergic terminals in artery and vein contained many small and a few large dense-core vesicles. At least 20% of the terminals in the artery contained many small agranular vesicles and a few large opaque vesicles; this suggests that they were of the cholinergic type; Such terminals were not found in intrapulmonary veins. Under conditions of controlled blood flow, stimulation of the sympathetic nerves to the lung and intralobar injection of norepinephrine increased pressure in the perfused lobar artery and small intrapulmonary vein in a stimulus-related manner. The rise in pressure in the lobar artery and vein in response to nerve stimulation was blocked after administration of either 5- and 6-hydroxydopamine; Neither agent modified the response of the pulmonary vascular bed to norepinephrine; In contrast, the rise in pressure in the lobar artery and vein in response to both norepinephrine and to nerve stimulation was blocked by phenoxybenzamine, an alpha-receptor blocking agent. The attenuated neurogenic vasoconstrictor response in dogs treated with 5- and 6-hydroxydopamine was associated with a marked decrease in intensity of fluorescence of the abundant adrenergic innervation in both intrapulmonary artery and vein, and with the appearance of an osmiophilic material in dense-core vesicles of adrenergic terminals in artery and vein. We believe that these data suggest that 5- and 6-hydroxydopamine interfere with adrenergic transmission in intrapulmonary vessels by depleting norepinephrine from adrenergic terminals. Furthermore, we conclude from hemodynamic, histochemical, and ultrastructural studies that vasomotor tone in the pulmonary vascular bed can be regulated by the sympathetic nervous system.

Animals↗