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J A Simson

Publications and source records attributed to J A Simson.

At least 37 records · Page 2Linked to original sources
PubMed1984

Freeze-fracture and lead ion tracer evidence for a paracellular fluid secretory pathway in rat parotid glands.

The morphology and permeability of tight junctions of the three major epithelial constituents of rat parotid gland-acinus, intercalated duct, and striated duct-have been examined ultrastructurally. Acinar and intercalated duct junctions (including those surrounding intercellular canaliculi) averaged two to three sealing strands, whereas striated duct junctions had five to eight sealing strands. When the permeability of the junctional complex was probed by means of a recently devised lead ion tracer technique, acinar junctions were found to be very permeable, intercalated duct junctions were somewhat permeable, and striated duct junctions were essentially impermeable to the tracer. Thus, by both morphological and tracer-permeability criteria, acinar tight junctions appear to be "leaky." These data provide strong evidence that, in rat parotid glands, a potential paracellular secretory pathway exists in the acinar region for the transepithelial passage of fluid.

Animals↗
PubMed1984

Localization of copper-zinc superoxide dismutase in the endocrine pancreas.

Immunoelectron microscopy and cellular fractionation on sucrose density gradients have been used to examine the intracellular distribution of copper-zinc superoxide dismutase (SOD) in the canine and rat endocrine pancreas. Using rabbit anti-canine copper-zinc SOD as the primary antiserum, immunostaining in canine beta and non-beta islet cells was significantly greater than that in serial sections of the same islet incubated with preimmune serum from the same rabbit. Within the cells, immunostaining was associated with spherical and crystalloid granules as well as with the cytoplasm. Radioimmune assays of cellular fractions or rat islet-cell preparations showed that the granule-rich fraction containing large amounts of insulin was also rich in SOD. This interesting observation of association of SOD with hormone-containing granules suggests that SOD may play a role in protecting these oxidation-sensitive proteins.

Animals↗
PubMed1984

Localization of corneal superoxide dismutase by biochemical and histocytochemical techniques.

Superoxide dismutase activity is found in the cornea of rats, dogs, rabbits and humans. A superoxide dismutase identical to the Cu-Zn enzyme is identified by biochemical and immunochemical methods in the corneal epithelium and endothelium in relative high abundance (90-100 U mg-1 protein). The enzyme quantities detected by radioimmune assay and bioactivity assay are similar, giving evidence that the enzyme present is biologically functional. Immunohistochemical techniques demonstrate the association of the enzyme with the cytoplasm of these layers. Soluble protein extracts of corneal stroma exhibit weak apparent superoxide dismutase activity which is found to be mainly due to copper associated with serum albumin.

Animals↗
PubMed1984

Immunocytochemical localization of nerve growth factor: effects of fixation.

The fixation dependence of immunocytochemically demonstrable nerve growth factor (NGF) was investigated. Several commonly used fixation methods have been employed, including buffered formaldehyde, Bouin's fluid, and chloroform-methanol, as well as freezing and cryostat sectioning. The immunostaining technique was an immunoenzyme bridge procedure on either paraffin sections or frozen sections. Of those methods tested, fixation for 1 hr in a buffered formaldehyde appeared to provide optimal preservation and localization of immunoreactive material. Using this method, reaction product was localized in granules of the granular tubule cells of the male mouse submandibular gland. Prolonged fixation in buffered formaldehyde resulted in a diffuse background staining and loss of granule immunoreactivity. In frozen sections and in tissues fixed with either Bouin's solution, chloroform-methanol, or buffered paraformaldehyde-glutaraldehyde increased cytoplasmic background staining and loss of granule immunoreactivity were observed. It was concluded that, for the localization of NGF at the light microscopic level, a brief (1 hr) buffered formaldehyde fixation is optimal.

Animals↗
PubMed1984

X-ray microanalysis: identification and quantification of elements in normal and pathologically altered cells.

It is apparent that advanced technology in X-ray microanalysis is rapidly becoming applicable to experimental cellular pathology. Additionally, it has already proven to be of significant value in diagnostic human pathology and clinical research, especially in the areas of environmental toxicology and forensic pathology. Like routine electron microscopy, X-ray microanalysis will soon be a necessary technology for any major medical center practicing 'state-of-the-art' medicine.

Calcinosis↗
PubMed1983

Ultrastructural responses by Golgi apparatus of rat submandibular gland to beta-adrenergic, alpha-adrenergic, and cholinergic stimulation.

Rat submandibular gland tissue pieces were stimulated in vitro for 30 min with a beta-adrenergic agent or a cyclic AMP analog to stimulate protein secretion, or with alpha-adrenergic or cholinergic agents or a Ca2+ ionophore to stimulate fluid secretion. Acinar cells were examined by transmission electron microscopy. In control tissue, acinar cells showed little evidence of secretory activity. The Golgi apparatus was sparse and was associated with a few small, immature secretory granules with fine fibrillar contents. Following secretory granule discharge stimulated by isoproterenol or dibutyryl cyclic AMP, acinar cells were constricted, and had extensive basolateral membrane folding and tightly packed rough endoplasmic reticulum. Golgi complexes were prominent and had multiple small granules with filamentous contents. After stimulation of fluid secretion by alpha-adrenergic agents (epinephrine, phenylephrine), or cholinergic agents (acetylcholine, carbachol, pilocarpine), or a Ca2+ ionophore (A23187), the Golgi apparatus had compact concave cisternae enclosing aggregates of tubulovesicles. Acinar cells were distended, basolateral membranes were expanded, and rough endoplasmic reticulum was dilated and vesiculated.

Acetylcholine↗
PubMed1983

Electron microscopic immunostaining of kallikrein in rat submandibular glands.

The subcellular localization of glandular kallikrein in ducts and tubules of the rat submandibular gland was determined using a postembedding immunostaining (peroxidase--antiperoxidase) technique on thin sections of Eponembedded tissue. Kallikrein was found in large granules of granular convoluted tubule cells and in small, apical granules of striated duct cells. It was also present in patchy aggregates along the surface of striated duct cells and intercalated duct cells, but not in granules of the latter. Basal dense bodies (lysosomes?) of granular tubules also stained for kallikrein. Absorption of kallikrein antiserum with rat urinary kallikrein, but not with rat urinary esterase A, abolished the specific immunostaining in these sites.

Animals↗
PubMed1983

The use of lead as an ionic tracer for investigating routes of passive fluid transfer.

Several inorganic ions, including lead, barium, silver, and thallium, have been tested as possible tracers for demonstrating fluid-accessible channels in functional epithelia at the ultrastructural level. The most useful of the ionic tracers examined was the lead (plumbous) ion, administered for short time intervals (less than 2 min) and "captured" with phosphate used as the buffer in the fixative. Passive fluid and ion-accessible channels of rat parotid salivary gland have been examined with this method. At short tracer infusion times (0.5-1.0 min), localization of the tracer was primarily extracellular, although intracellular deposits were observed in the following sites: smooth membrane-delimited endocytic vesicles of both epithelial and connective tissue cells, inner Golgi cisternae, and occasional cisternae of rough endoplastic reticulum. The lead tracer readily penetrated tight junctions between parotid acinar cells but rarely passed through the tight junctions between intercalated duct cells and did not penetrate junctions of striated duct cells. Fat cells observed in the stroma of this gland were the only cells that exhibited lead tracer in the cytosol, suggesting that the plasmalemma of this cell type is more permeable to exogenous ions than the plasmalemma of other cell types present in this gland.

Animals↗
PubMed1982

The histology and fine structure of glands in the rat respiratory tract.

The structure of rat respiratory glands has been investigated by light and electron microscopy. The glands exhibited a tubulo-acinar organization. Individual secretory units were composed of serous tubules or serous demilunes and mucous tubules with narrow lumens at the blind end (proximally), and of mucous ducts with wide lumens which opened to the tracheal lumen distally. Near the junction of the duct with the trachea, mitochondria-rich cells and a few ciliated cells were interspersed with mucous cells. It was found that the histology as well as the ultrastructure of the secretory product of these gland cells varied depending upon the location of the glands in the airway. For this reason, the glands of the epiglottis, larynx and trachea have been described separately. Epiglottal glands consisted of many mucous tubules, a few serous elements and an occasional mucous duct. Laryngeal glands contalned many serous and mucous tubules and a few mucous ducts. Tracheal glands were composed of serous tubules, a few mucous tubules and prominent bucous ducts. Serous tubule cell granules formed a uniform population within a cell profile but varied in cells of the epiglottis, compared with those of the larynx and trachea. Granules in mucous tubule cells differed from those of serous cells. Mucous cell granules also appeared uniform within a single cell but differed from cell to cell and at different levels of the respiratory tract. A particular granule type was predominant at each level. Cells of mucous ducts differed somewhat from those of mucous tubules and comprised two general secretory cell populations. Proximal mucous duct cells contained abundant granules that generally resembled those of mucous tubule cells but were localized in two areas of the cytoplasm. Dilated cisternae of rough endoplasmic reticulum with a bizonal content similar in density of zones seen in mature granules further characterized proximal mucous duct cells. The distal mucous duct cell generally contained sparse apical granules and lacked dilated rough endoplasmic reticulum.

Animals↗
PubMed1982

Distribution of mitochondrial calcium: pyroantimonate precipitation and atomic absorption spectroscopy.

Mitochondrial function is highly dependent upon the concentrations of cations within the various compartments of this organelle. Utilizing variants of the pyroantimonate precipitation method, we have undertaken to localize cations, particularly calcium, in isolated mitochondria. Precipitated cations were present in two major compartments: 1) within the intracristal space and 2) in the matrix, frequently in association with the matrix face of cristal membranes. Precipitated cations were abundant in mitochondrial samples fixed with most pyroantimonate-containing fixatives, but were usually absent in samples fixed in phosphate-buffered, pyroantimonate-containing fixative solutions. Atomic absorption spectroscopy demonstrated that Ca2+ added to mitochondrial suspensions prior to fixation was retained in the mitochondrial pellet if 0.1 M collidine was present as the fixative buffer. When the same concentration of phosphate-buffered pyroantimonate-osmium fixative was employed, however, much of the added Ca2+ was lost to the supernatant. The suborganellar localization of cations was influenced by the presence of added respiratory substrate. Incubation of mitochondria in an isoosmotic buffered sucrose medium without succinate favored localization of precipitates in the intracristal space of the outer compartment. In the presence of succinate, the localization of precipitates was shifted toward the matrix compartment. This redistribution was particularly obvious in samples to which Ca2+ had been added and was blocked by the addition of antimycin. The observation of precipitated cations in the outer mitochondrial compartment supports previous evidence for a calcium-binding protein in this compartment.

Animals↗
PubMed1981

Cytochemical localization of glycoconjugates in rat peritoneal mast cells during degranulation.

Cytochemical methods for the localization of glycoconjugates including concanavalin A-horseradish peroxidase (ConA-HRP) and dialysed iron were used to study the distribution of glycoconjugates in mast cell granules during degranulation. The ConA-HRP method revealed intense staining of discharged mast cell granules. Dialysed iron staining was seen at the granule periphery, with extruded granules exhibiting more intense staining than undischarged granules.

Animals↗
PubMed1979

Kallikrein localization in rodent salivary glands and kidney with the immunoglobulin-enzyme bridge technique.

Kallikrein has been localized in rodent kidney and salivary glands by means of an immunoglobulin-enzyme bridge technique. In sections of kidney, anti-kallikrein antibodies bound to the apical region of certain distal tubule segments in the cortex, to reabsorption droplets of proximal convoluted tubules, and to certain duct segments in the papilla. In salivary glands of both male and female rats and mice, and apical rim of most striated duct cells of submandibular, parotid and sublingual glands and granular tubules of submandibular glands exhibited immunoreactivity. Granular intercalated duct cells in female submandibular glands also displayed immunostaining for kallikrein. Phenylephrine administration resulted in loss of immunoreactive granules from the granular convoluted tubule cells of male mouse submandibular gland. This response was paralleled by a biochemically demonstrable decrease in kallikrein-like tosylarginine methyl ester (TAME) esterase activity.

Animals↗
PubMed1979

X-ray microanalysis of pyroantimonate-precipitable cations.

Modifications of the Komnick potassium (pyro)antimonate precipitation method have been widely used for the subcellular localization of a variety of cations. The identity of cations precipitated with this method has often been controversial, and it is therefore important to establish definitive criteria for identifying precipitated cations in situ. In the present study, we have precipitated antimonate salts in vitro and examined the salts both in crystalline powder form and after embedment in Epon, using energy-dispersive X-ray microanalysis, in an attempt to identify biologically important antimonate-precipitable cations. We have found that the cations sodium, magnesium, and calcium, if present in physiological concentrations, will precipitate antimonate under "standard" conditions (2.5% antimonate, pH 7.2 - 7.4, in the presence of 1% OsO4). Characteristic X-ray emissions were observed for sodium and magnesium, as well as for lead similarly precipitated, but Lalpha and Lbeta emission peaks from antimony interfered with calcium identification and necessitated complex computerized deconvolution or peak stripping to determine the presence of a calcium peak. Precipitates of sodium did not contain appreciable potassium, whereas variable amounts of potassium were present in precipitates of calcium and lead, depending upon the extent of washing prior to dehydration. Sizeable potassium peaks were consistently present in even well washed magnesium precipitates. X-ray spectra of standardized precipitates were found useful as an aid in interpreting the more complicated spectra obtained from tissue samples.

Animals↗
PubMed1978

Secretagogue-mediated discharge of nerve growth factor from granular tubules of male mouse submandibular glands: an immunocytochemical study.

Submandibular glands of male mice were stained for nerve growth factor by light microscopic immunocytochemistry. Nerve growth factor (NGF) was present in the granules of granular tubule cells, with the immunoreactive material often concentrated at the periphery of granules. Administration of the alpha-adrenergic agent, phenylephrine, to animals resulted in a marked depletion of NGF-containing granules from granular tubules. Some release also occurred following administration of the beta-adrenergic agent, isoproterenol. Cholinergic stimulation (pilocarpine) did not result in appreciable loss of immunoreactive granules from these cells. In vitro results were not as clear cut, immunocytochemically, as those obtained with intact animals. It is concluded that discharge of NGF from male mouse submandibular glands is mediated predominantly by alpha-adrenergic activation, and that this phenomenon is readily demonstrated in the intact animal.

Animals↗
PubMed1978

Cytochemistry of the skin of patients with mucopolysaccharidoses.

The distribution of complex carbohydrates has been investigated at the light and electron microscope levels in sweat glands of normal subjects and patients with Hurler's or Hunter's disease. Normal sweat glands examined with a battery of light microscopic histochemical methods revealed sulphated complex carbohydrate in secretory granules of the dark cells. These granules lacked affinity for dialysed iron (DI) at the light and electron microscope levels. The DI method demonstrated acid complex carbohydrates ultrastructurally on the surface of the intercellular canaliculi and central lumen in normal sweat glands. DI-reactive acidic material, presumably of mucopolysaccharide nature, surrounded and extended between collagen bundles in the stroma of normal skin, but was absent from the band which ensheathed the sweat gland and consisted of individual rather than bundled collagen fibrils. DI-reactive mucopolysaccharide lined and partially filled vacuoles of dark cells showing a laminar distribution in vacuoles of clear cells in sweat glands of a Hunter patient. The DI method also visualized mucopolysaccharide distributed throughout vacuoles in fibroblasts of this patient. DI-reactive acid material covered the luminal surface of the sweat gland, coated collagen bundles in the stroma and spared the periglandular collagenous sheath in skin from Hurler and Hunter patients as in that from normal controls. Acid phosphatase was localized ultrastructually in vacuoles and nearby cytoplasm and on plasmalemmae of clear cells, dark cells and myoepithelial cells of sweat glands from Hurler and Hunter patients. Vacuoles of dermal fibroblasts and Schwann cells in these specimens also exhibited strong acid phosphatase activity.

Female↗
PubMed1978

Morphology and cytochemistry of acinar secretory granules in normal and isoproterenol-treated rat submandibular glands.

Several fixation procedures have been utilized in a fine-structural study of rat submandibular glands with the aim of correlating the morphology of granule substructure with its composition. Procedures included fixation with aldehyde in a variety of buffers, with or without fixation additives such as tannic acid or calcium chloride. Both immersion and perfusion fixation studies were performed. Osmium tetroxide postfixed tissue was compared with non-postfixed tissue. Thin sections were stained for carbohydrate-containing constituents by either periodic acid-thiocarbohydrazide-silver proteinate or tannic acid-ferric chloride sequences. The morphology and cytochemistry of acinar secretory granules were highly dependent upon the fixation procedure utilized. In postfixed tissue, fine filaments and vesicles were the major granule constituents. Filaments often aggregated into fibrils in fixatives containing phosphate buffer or calcium, whereas vesicles were prominent with fixatives containing collidine buffer. Tannic acid, as a fixation additive, imparted enhanced density to the peripheral rim of aggregated filaments. If post fixation was eliminated, an amorphous meshlike material was the major granule component. This stained readily with methods for carbohydrate whereas the granules of post-osmicated tissue did not. Following chronic isoproterenol treatment the degree of filament aggregation in postfixed tissue was augmented, and this corresponded to an increase in amount of material stainable for carbohydrate in non-post-osmicated tissue.

Animals↗