Search PubMed⌕ Search

Biomedical subjects

A R Hand

Publications and source records attributed to A R Hand.

At least 109 records · Page 6Linked to original sources
PubMed1984

Cyclic AMP binding proteins in saliva.

Cyclic adenosine 3',5'-monophosphate (cyclic AMP)-binding proteins which have the characteristics of cyclic AMP-dependent protein kinase (E.C. 2.7.1.37) regulatory subunits, have been identified in rat and human saliva. Concentration of these proteins was increased in rat saliva after stimulation with isoproterenol, suggesting that they were released during exocytosis. Cyclic AMP-dependent protein kinase catalytic activity was not measurable in saliva of either species.

Animals↗
PubMed1984

Isoproterenol-induced changes in glutathione metabolism in the rat parotid gland.

Rat parotid glands were removed at timed intervals after intraperitoneal injection of isoproterenol (IPR). Reduced/oxidized glutathione ratios, glutathione peroxidase, glutathione reductase and amylase activities were determined. Parotid gland amylase content fell to less than 5 per cent of control values within 1 h after IPR, then slowly returned to control levels by 24 h. The ratio of reduced/oxidized glutathione was decreased at 2 h after IPR injection, returned to near control values at 6 h, then increased above control levels at 9, 12 and 24 h. Glutathione peroxidase activity was increased only at 12 h after injection of IPR, whereas glutathione reductase activity initially decreased, then reached peak values at 12 h. These results indicate that alterations in metabolic activity during the secretory cycle are accompanied by changes in the reduced/oxidized glutathione ratio and the activity of glutathione-metabolizing enzymes. Cellular events contributing to these alterations in glutathione metabolism may include exocytosis, endocytosis and membrane recycling, increased amino-acid transport and resynthesis of secretory proteins.

Amylases↗
PubMed1984

Alteration of tight junctional permeability in the rat parotid gland after isoproterenol stimulation.

The permeability of junctional complexes to ultrastructural tracers of different molecular weight and the freeze-fracture appearance of junctional structure were investigated in the resting and stimulated rat parotid gland. Tracers were administered retrogradely via the main excretory duct, and allowed to flow by gravity (16 mmHg) into the gland for 15-60 min. Secretion was induced in some animals by intraperitoneal injection of isoproterenol. In resting glands, the tracers microperoxidase , cytochrome c, myoglobin, tyrosinase (subunits), and hemoglobin were restricted to the luminal space of the acini and ducts. In glands stimulated 1-4 h before tracer administration, reaction product for microperoxidase , cytochrome c, myoglobin, and tyrosinase was found in the intercellular and interstitial spaces, whereas hemoglobin was usually retained in the lumina. In contrast, horseradish peroxidase and lactoperoxidase appeared to penetrate the tight junctions and reaction product was localized in the extracellular spaces in both resting and stimulated glands. Diffuse cytoplasmic staining for horseradish peroxidase and lactoperoxidase was frequently observed in acinar and duct cells. The distribution of horseradish peroxidase was similar in both Sprague-Dawley and Wistar-Furth rats, and at concentrations of 0.1-10 mg/ml in the tracer solution. Freeze-fracture replicas of stimulated acinar cells revealed an increased irregularity of the tight junction meshwork, but no obvious gaps or discontinuities were observed. These findings indicate that (a) tight junctions in the resting rat parotid gland are impermeable to tracers of molecular weight greater than or equal to 1,900; (b) stimulation with isoproterenol results in a transient increase in junctional permeability allowing passage of tracers of molecular weight less than or equal to 34,500; (c) junctional permeability cannot be directly correlated with junctional structure; and (d) the behavior of horseradish peroxidase and lactoperoxidase in the rat parotid gland is inconsistent with their molecular weights. Cell membrane damage due to the enzymatic activity or binding of these two tracers may account for the observed distribution.

Animals↗
PubMed1984

Microheterogeneity of rat parotid gland proteins after chronic treatment with isoproterenol.

Two ultrasensitive methods were employed to determine the effect of repeated in vivo stimulation with isoproterenol on the protein composition of parotid acinar cells. Silver staining showed electrophoretic banding pattern changes in a wide range of cellular proteins during and after multiple injections of the beta-adrenergic agonist. Photo-affinity labeling with [32P]-N3-cyclic AMP showed the disappearance and eventual return (after discontinuation of the injections) of the cellular cyclic AMP-binding proteins as measurable cellular components. These findings indicate that major translation-associated changes may occur in target cell protein composition both during and after hormonal stimulation.

Affinity Labels↗
PubMed1984

Regulation of tight junctional permeability in the rat parotid gland by autonomic agonists.

The permeability of tight junctions in the rat parotid gland to the ultrastructural tracer myoglobin (m.w. 17,800) was investigated after in vivo stimulation by autonomic drugs. At various times after administration of beta-adrenergic (isoproterenol), alpha-adrenergic (methoxamine), or cholinergic (methacholine) agonists, the parotid duct was cannulated, and a solution of myoglobin was allowed to flow by gravity (16 mm Hg) into the gland for one hr. In resting glands, cytochemical reaction product for myoglobin was localized in the luminal space of acini and ducts. The tracer was also localized to the luminal space after stimulation with methacholine and methoxamine. In contrast, one to four hr after isoproterenol stimulation, reaction product was present in the intercellular and interstitial spaces of the gland. At later times after stimulation (from six to 24 hr), the tracer was again restricted to the luminal space of the acini and ducts. These results indicate that isoproterenol stimulation causes a transient increase in tight junctional permeability, whereas stimulation with methoxamine or methacholine does not change junctional permeability to myoglobin.

Animals↗
PubMed1984

Effects of secretory stimulation on the Golgi apparatus and GERL of rat parotid acinar cells.

The structure and cytochemistry of the Golgi apparatus and GERL of rat parotid acinar cells was studied after in vivo secretory stimulation with isoproterenol. Discharge of mature secretory granules was complete within 1 hr after isoproterenol injection, but immature granules in the Golgi region or near the lumen were not released. At early times (1-5 hr) after isoproterenol, acid phosphatase (AcPase) activity was markedly increased in GERL and immature secretory granules compared to uninjected controls. GERL appeared increased in extent and numerous continuities with immature granules were observed. Reaccumulation of mature secretory granules was first evident at 5 hr, and was almost complete by 16 hr after isoproterenol. Thiamine pyrophosphatase (TPPase) activity, normally restricted to the trans Golgi saccules, was frequently present in immature granules during this time. Narrow cisternae resembling GERL, occasionally in continuity with immature granules, also contained TPPase reaction product. By 16-24 hr after stimulation, the activity and distribution of AcPase and TPPase were similar to control cells. These results demonstrate the dynamic nature of the Golgi apparatus and GERL in parotid acinar cells, and emphasize the close structural and functional relationship between these two structures.

Acid Phosphatase↗
PubMed1984

The Golgi apparatus and GERL during postnatal differentiation of rat parotid acinar cells: an electron microscopic cytochemical study.

Morphological and cytochemical changes in the Golgi apparatus and GERL of differentiating parotid acinar cells were examined in Sprague-Dawley rats from 5 days to young adult. At day 5, the Golgi apparatus consisted of 3-6 narrow saccules, with short segments of GERL lying adjacent to the trans Golgi saccule. As the glands matured, the Golgi apparatus increased in size and the saccules became broadened and fenestrated reaching a maximum from days 15-20. The saccules subsequently narrowed slightly and by day 25 resembled those seen in young adults. Numerous cisternae of GERL could be seen at the trans face during this period. While the glands were maturing, marked changes occurred in the distribution of thiamine pyrophosphatase (TPPase) activity in the Golgi saccules. In the immature cells, TPPase activity was restricted to 1 or 2 trans Golgi saccules. However, by day 10 TPPase could also be localized in immature secretory granules and in GERL-like cisternae. Unreactive segments of GERL were also present. This pattern of localization persisted until day 20, after which the TPPase activity in the GERL-like cisternae diminished gradually until by day 40 TPPase again was localized in 1-2 trans Golgi saccules and an occasional immature secretory granule. Acid phosphatase (AcPase) activity was localized primarily in lysosomes in the very young animals and increased in GERL with age up to day 15. From days 15 to 20 there was a decrease in the amount of activity seen in GERL, but from day 20 on, the AcPase activity increased until it reached that seen in young adult animals. These results indicate that the presence of TPPase activity in GERL-like cisternae and immature secretory granules may be dependent upon the developmental as well as the physiologic state of the acinar cells and lend further support to the suggestion that GERL is derived from the trans Golgi saccules.

Acid Phosphatase↗
PubMed1984

Rat parotid cell function in vitro following X irradiation in vivo.

The effect of X irradiation on rat parotid acinar cell function was evaluated in vitro 1, 3, and 7 days following in vivo exposure to 2000 R. Several cellular functions were followed: protein secretion (amylase release), ion movement (K+ efflux and reuptake), amino acid transport (alpha-amino[14C]isobutyric acid), and an intermediary metabolic response ( [14C]glucose oxidation). In addition both the morphologic appearance and in vivo saliva secretory ability of parotid cells were assessed. Our results demonstrate that surviving rat parotid acinar cells, isolated and studied in vitro 1-7 days following 2000 R, remain functionally intact despite in vivo diminution of secretory function.

Aminoisobutyric Acids↗
PubMed1984

Effects of streptozotocin-induced diabetes on the rat parotid gland.

The structure of the rat parotid gland was studied in male rats from 4 hours up to 1 year after induction of diabetes by the administration of streptozotocin (STZ, 65 mg/kg). Blood glucose and triglyceride levels were markedly increased, and plasma insulin levels were significantly decreased within 24 hours after STZ. The earliest detectable alteration in acinar cell structure was the presence of small lipid droplets in the basal cytoplasm at 24 hours. Lipid accumulation continued, reaching a peak at 4.5 months after STZ, when the acinar cells contained large lipid vacuoles. By 1 week the Golgi apparatus was enlarged and GERL was prominent at the trans Golgi face. Membrane-bound cytoplasmic crystalloids occurred in acinar cells 1 month after STZ administration and were numerous in older animals (10 to 12 months). These crystalloids occasionally were reactive for trimetaphosphatase, a cytochemical marker for lysosomes. Similar crystalloids as well as large, dense, phagosome-like bodies were also present in the striated duct cells. Macrophages containing acinar cell debris and crystalloids were frequently observed, often in association with the intercalated ducts. Focal alterations in the basement membranes, consisting of multiple layers, loops, and amorphous patches, and "redundant" folds, occurred as early as 2 months and were relatively frequent 10 to 12 months after STZ administration. These results suggest that maintenance of the normal structure and function of the rat parotid gland may, in part, be insulin dependent.

Animals↗
PubMed1983

Nuclear cAMP-dependent protein kinase in rat parotid acinar cells.

Receptor interactions of parotid acinar cells with beta-agonists are mediated by cyclic 3',5'-monophosphate (cAMP) and expressed as cAMP-dependent protein kinase (cAPK) activation. In addition to its location in the cytoplasm, we have shown that cAPK is associated with the nuclear non-histone protein (NHP) fraction (0.35 M NaCl extract) of rat parotid acinar cells. Nuclei were prepared from isolated parotid acini with minimal contamination from other cell types or cytoplasmic components. The nuclear cAPK activity was inhibited by the thermostable inhibitor and was stimulated by the addition of exogenous cAMP to the assay, indicating that the enzyme is present in the holoenzyme form. Enzyme activity was not increased in the presence of detergent, suggesting that cAPK is not bound to the nuclear membrane. Photoaffinity-labeling studies with an 8-azido analog of cAMP showed that regulatory subunits of both type I and type II cAPK isozymes are present in parotid cell nuclei. Short-term in vitro stimulation of the acini with 10(-6) M isoproterenol did not alter cAPK activity in the nuclear fraction. These findings indicate that compartmentation of cAPK into nuclear and extranuclear locations in rat parotid acinar cells is similar to that of several other cell types which are responsive to hormonal stimulation.

Animals↗
PubMed1983

A morphologic study of the recovery of the rat submandibular gland after retrograde infusion. I. Water-soluble radiographic contrast medium.

The recovery of the rat submandibular gland after retrograde infusion of water-soluble radiographic contrast medium was studied using an experimental model. During continuous monitoring of the developing intraglandular pressure, the glands were subjected to ductal and slight parenchymal filling or heavy parenchymal filling with the medium. The animals were killed after varying recovery periods, and the tissue was prepared for light and electron microscopic examination. Dilation of the ductal lumina, induced during ductal and slight parenchymal filling, was successively reduced and, generally, the parenchyma had a normal appearance at 30 h. In glands subjected to heavy parenchymal filling, the changes in the intralobular ducts were more pronounced and were also seen at later times after infusion. Alterations in the acini, comprising fusion of secretory granules, vacuole formation and dilation of the acinar lumina and intercellular canaliculi, were observed. At later times, atrophy of the parenchymal cells occurred together with an apparent proliferation of the connective-tissue stroma, as well as an increase in the number of small blood vessels. An inflammatory cell-infiltrate was seen in both groups of animals, but was most prominent in glands subjected to heavy parenchymal filling. The infiltrate, comprised primarily of macrophages and polymorphonuclear leukocytes, reached a peak at 20 h after infusion. At later times, mast cells and occasional eosinophils were seen. The observed alterations and the pattern of recovery are most likely due to the induced intraglandular pressure and the following inflammatory reaction. It is also possible that the changes, to some extent, are influenced by the presence of the contrast medium in the tissue.

Animals↗
PubMed1983

A morphologic study of the recovery of the rat submandibular gland after retrograde infusion. II. Lipid-soluble radiographic contrast medium.

Lipid-soluble radiographic contrast medium was infused retrogradely through the main excretory duct of the rat submandibular gland until ductal and slight parenchymal filling or heavy parenchymal filling was achieved, as determined by the developing intraglandular pressure. The glandular tissue was fixed by vascular perfusion at different times following infusion, and examined by light and electron microscopy. Dilation of the intralobular ducts and scalloping of the luminal border were pronounced after both degrees of filling. Widening of the acinar lumina and intercellular canaliculi occurred early. Masses of fused secretory granules were commonly seen in the cytoplasm of the acinar cells and formation of vacuoles occurred frequently. In some acinar cells, densely packed granules filled the major part of the cytoplasm. Large lysosomes and autophagic vacuoles, frequently present in the various parenchymal cells, often contained apparent contrast medium. In addition, widening of the intercellular spaces between parenchymal cells was seen, particularly in the acini and intercalated ducts. An inflammatory cell-infiltrate, primarily comprised of polymorphonuclear leukocytes, was particularly prominent at 20 h and 30 h after infusion. The changes were generally more pronounced and persisted for a longer time in glands subject to heavy parenchymal filling. Large cyst-like spaces surrounded by inflammatory cells were seen in the lobules and in the interlobular connective tissue of these glands. At later times, areas containing apparent contrast medium surrounded by macrophages, were frequently observed in the connective-tissue stroma. Atrophy of the parenchymal cells was seen later, after heavy parenchymal filling, and a proliferation of the connective tissue had occurred. The changes were most probably caused by the elevated intraglandular pressure induced during infusion, and the subsequent cell damage and inflammatory reaction. A foreign body reaction, induced by the retained lipid-soluble contrast medium, was probably partly responsible for the morphological alterations observed, following infusion.

Animals↗
PubMed1983

Enzyme modulation of the Golgi apparatus and GERL: a cytochemical study of parotid acinar cells.

The distribution of thiamine pyrophosphatase (TPPase) and acid phosphatase (AcPase) has been examined in resting parotid acinar cells as well as during decreased and increased secretory granule production. In resting acinar cells, TPPase activity was restricted to the trans Golgi saccules and AcPase activity was localized in GERL and immature secretory granules. Although secretory granule production is diminished during ethionine intoxication, no significant alteration in the distribution of either TPPase or AcPase was noted. However, marked changes in enzyme localization, especially of TPPase, occurred during accelerated secretory granule production. The alterations were essentially the same for all of the conditions studied (recovery from ethionine treatment, recovery from a protein depletion diet, secretory stimulation with isoproterenol, and postnatal maturation of the parotid gland). During maximal secretory granule production, TPPase activity was localized not only in the trans Golgi saccules, but also in GERL-like cisternae and immature secretory granules. The immature secretory granules were often in continuity with the GERL-like cisternae. At the same time that the TPPase activity was increased, the AcPase activity was frequently diminished. These modulations in enzyme activity provide evidence that GERL is derived from the trans Golgi saccule.

Acid Phosphatase↗
PubMed1983

Bromoacetylalprenololmenthane: a potent irreversible antagonist of beta adrenergic elicited protein exocytosis in rat parotid cells.

The interaction of bromoacetylalprenololmenthane (BrAlpM), an irreversible beta adrenergic receptor antagonist, with rat parotid acinar cells was studied in vitro. In the presence of BrAlpM, the rate of (-)-isoproterenol-induced exocrine secretion from cells, measured as percentage of amylase release, was markedly reduced. The concentration of (-)-isoproterenol required to elicit half-maximal protein secretion was about 100 times greater (5 microM) in the presence of 1 microM BrAlpM than in control incubations (0.05 microM). BrAlpM and propranolol were similar in their ability to inhibit parotid protein release (IC50 approximately 10(-7) M). To demonstrate that BrAlpM functioned as an irreversible beta adrenergic antagonist, cells were preincubated with BrAlpM for varying amounts of time and then washed three to six times before adding (-)-isoproterenol. At least 10 min preincubation was required to show irreversibility. Alprenolol, under the same preincubation conditions, was unable to inhibit amylase release. BrAlpM inhibited the binding of [3H]dihydroalprenolol to parotid beta adrenoreceptors over a concentration range similar to that required for inhibition of protein secretion. Cells incubated in the absence or presence of BrAlpM displayed a comparable morphologic appearance when viewed by light and electron microscopy. The degree of inhibition of isoproterenol-induced exocytosis of secretory granules by BrAlpM appeared to vary from cell to cell. These findings suggest that BrAlpM should be a useful probe to study beta adrenoreceptor function and metabolism in rat parotid acinar cells.

Adrenergic beta-Antagonists↗
PubMed1982

A light and electron microscopic study of the distribution and effects of water-soluble radiographic contrast medium after retrograde infusion into the rat submandibular gland.

For microscopic visualization, horseradish peroxidase (HRP; 10 mg/ml) was added to the contrast medium. Some glands were infused with saline solution containing HRP. During continuous infusion, the intraglandular pressure was recorded. Infusion was stopped at different phases of the pressure curve and the glands fixed by vascular perfusion. Morphological alterations, principally dilatation of the intralobular ducts, were most pronounced in the intercalated duct segment. HRP was first observed in the lumina of the intralobular ducts and acini but gained access to the intercellular spaces thought the apical junctional complexes and subsequently surrounded various cellular components. Eventually the tracer was found in blood and lymphatic vessels. Because of an uneven distribution of the tracer and variation in the degree of filling in different areas of the same gland, the development of the intraglandular pressure could not be directly correlated with specific morphological alterations but is thought to reflect all events occurring in the tissue at a particular time.

Animals↗