Carl J. Pfeiffer

Modulating Action of Melatonin on Serotonin‐Induced Aggravation of Ethanol Ulceration and Changes of Mucosal Blood Flow in Rat Stomachs

Effects of melatonin and serotonin on ethanol ulceration and mucosal blood flow in the rat stomach were investigated. Melatonin and serotonin (5‐HT) administration did not produce observable gastric injury in the ex vivo stomach, but the 5‐HT dose dependently reduced glandular mucosal blood flow (GMBF) in this organ. Ethanol depressed GMBF and induced visible glandular mucosal injury. The latter effect was prevented by melatonin preincubation. Serotonin pretreatment aggravated the gastric mucosal injury and GMBF changes induced by ethanol; these actions were partially reversed by melatonin. The findings indicate that the GMBF and gastric injury are related; the reduction in GMBF, however, may not be the sole factor responsible for ulceration. The antagonistic effects of melatonin on 5‐HT action on the stomach suggest that melatonin may act as a modulator for 5‐HT action on the gastrointestinal tract.

Reduction of colonic mucus by repeated short-term stress enhances experimental colitis in rats.

The role of stress in inflammatory bowel disease remains debated and few studies have tested the role of stress in conjunction with experimental animal models of colitis. In this investigation we tested the hypothesis that cold-restraint stress would adversely effect the severity of 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced colitis in rats, and examined mechanisms for the response. Results indicated that increasing intermittent prior exposures to stress significantly enhanced TNBS-induced colitis severity. An associated stress-induced decrease in colonic mucin glycoprotein content, reduction in goblet cells, and histochemical mucin suggested reduced mucin was a pathogenetic factor. Myeloperoxidase content increased and mast cell counts in the colon decreased but colonic permeability only temporarily increased with increasing stress exposure. Prior adrenalectomy or administration of an adrenergic blocking agent did not prevent the colonic changes to stress, but mast cell stabilization or inhibition of cholinergic pathways reduced the stress-induced colonic changes.

Induction of blood cells in Xenopus embryo explants

Abstract A Xenopus-specific anti-leukocyte monoclonal antibody designated XL-2 was isolated and used to identify leukocytes in tailbud embryos and activin A-treated explants of blastula animal cap. XL-2 bound to a 135-kDa polypeptide in western blots of protein extracts from adult thymocytes, tailbud embryos, tadpoles, and explants. In cell suspensions, it immunostained the cell surface of all types of adult leukocytes including lymphocytes, monocyte/macrophages, thrombocytes, and granulocytes. At embryonic stage 24, immunocytochemistry revealed XL-2-positive leukocytes, the earliest time at which such cells have been recognized. Whole-mount staining of tailbud embryos and tadpoles showed a widely dispersed population of XL-2-reactive leukocytes, many of which had elongated shapes and ameboid pseudopodia. In activin A-treated animal caps, XL-2 recognized a subpopulation of cells within the lumen of the central fluid-filled cavity as well as cells in the interstitium of mesenchymal and mesothelial components of the explant. Together, activin A and human interleukin-11 induced 100% of explants to form lumenal blood cells. Compared to activin A alone, murine stem cell factor plus activin A significantly increased the numbers of XL-2-reactive leukocytes and erythrocytes. These results support the view that activin A induces leukocyte and erythrocyte progenitors during Xenopus embryogenesis.

Ultrastructure of the olfactory organ of the newt, Cynops pyrrhogaster.

The ultrastructure of the nasal sacs of the Japanese newt, Cynops pyrrhogaster, was studied by scanning and transmission electron microscopy. The paired nasal sacs of the newt are dorsoventrally flattened with a lateral nasal sinus off the main cavity of each sac. Throughout each sac is a series of ridges and grooves. In the main cavity, sensory epithelium with ciliated and microvillous receptor cells lines the grooves, and a thin, ciliated non-sensory epithelium lines the ridges. Secretory glands are present in the lamina propria. In the lateral nasal sinus, the ridges are lined with a thick, non-ciliated sensory epithelium that lacks glands. This region resembles and may function as a primitive vomeronasal organ.

Effects of chronic nitric oxide synthase inhibition in cold-restraint and ethanol-induced gastric mucosal damage in rats.

Gastric actions of Nw-nitro-1-arginine methyl ester (L-NAME) were investigated in rats, as this agent is a reliable nitric oxide synthase inhibitor L-NAME solutions were placed in subcutaneous osmotic minipumps which continuously released L-NAME at 0.1, 1.0, 10, or 40 mg/kg/day. L-NAME dose and time-dependently enhanced stress-induced gastric ulceration but did not affect mucosal mast cell population. Ulcerogenic actions of L-NAME were reversed by L-arginine but not by D-arginine. Ten L-NAME treatment also enhanced the ethanol-induced gastric mucosal damage, depressed gastric mucosal blood flow but did not alter gastric mucus, secretory volume, or acid output. It is concluded that in the present models, chronic nitric oxide synthase inhibition enhanced ulcerogenesis by decreasing mucosal resistance due to reduced mucosal blood perfusion. This implicates nitric oxide as a mucosal defense factor which acts in part by maintaining mucosal blood flow.

Epidermal lipid in several cetacean species: ultrastructural observations.

The ultrastructure of the skin of four cetacean species, bottlenose dolphin (Tursiops truncatus) long-finned pilot whale (Globicephala melaena), humpback whale (Megaptera novaeangliae), and fin whale (Balaenoptera physalus) was investigated with particular reference to epidermal lipid. It has already been established that massive lipid reservoirs exist in whales, that the biochemical structures of cetacean lipids are unique, and that unusual intracellular lipid droplets appear in the epidermis. We report here some novel findings on scanning electron microscopic morphology of epidermal lipid, and on its ultrastructural morphology in general and specialized integumentary sites, including species not previously investigated. The intracellular epidermal lipid droplets were more extensive than lamellar body-derived intercellular lipid which is within the interstices of stratum externum cells. The intracellular droplets were spherical, highly variable in size ranging from 0.24 μm to 3.0 μm in diameter, appeared singly or were aggregated in cytoplasmic cavitations, and often were closely associated with epidermal cell nuclei. Evidence for exocytosis of the intracellular droplets was not observed. Significant numbers of intracellular lipid droplets are not observed in the epidermis of terrestrial mammals, so their presence is one of several aquatic specializations of the cetacean integument. Its full significance remains obscure, but it is more probably associated with epidermal cell metabolism than with secretion of lipid.

Early ultrastructural changes in rat duodenal mucosa associated with cysteamine-induced ulcer

The early morphologic sequelae induced by the duodenal ulcerogen, cysteamine, have been studied in rats by transmission electron microscopy. Cysteamine was administered per os at 70 mg/100 g body wt to groups of female rats sacrificed at 30 min, 1, 2, 4, 8, 12, 20, and 24 hr after chemical treatment, and duodenal tissue sampled from the antimesenteric side of the proximal duodenum, where ulcers develop, was studied. Emphasis was placed on early times as our previous scanning electron microscopic data had demonstrated enhanced in situ cellular necrosis and surface cavitation at 2-4 hr after cysteamine treatment. Results indicated intracellular changes as early as 30 min after treatment and prior to damage of the columnar cell microvilli or epithelial tight junctions. A staging of observed cellular degenerative changes suggested early apical endoplasmic reticular swelling and loss of cytoplasmic ground substance, followed later by moderate internal disruption of mitochondria. Through these stages the cell surface microvilli remained morphologically normal. Subsequently, microvilli degenerated and mitochondrial fine structure became severely disrupted and cell contents were expelled. Deeper villous changes such as separation of columnar cells from the lamina propria and alterations of selected elements within the lamina propria were observed. These data suggest that intracellular cytotoxic reactions at the villous tips occur early and may precede the influence of intraluminal damaging factors induced by cysteamine.

Gastric leiomyomas in the Japanese newt, Cynops pyrrhogaster; ultrastructural observations.

Nineteen of 700 outwardly healthy captive adult Japanese newts, Cynops pyrrhogaster, had nodular neoplasms protruding on the gastric serosal surface. These tumours were characterized as sharply circumscribed leiomyomas of the muscularis externa with occasional submucosal involvement. Ultrastructural analysis of tumour myocytes revealed irregular-shaped, well-differentiated cells with cytoplasmic processes, and reduced quantities of intracellular myofibrils. They were surrounded by enlarged intercellular spaces filled with disorganized and increased amounts of collagen. Vacuolation was seen both in tumour myocytes and in mucous epithelial cells. Virus-like particles were observed in nuclei of some tumour myocytes. Interstitial cells with laminated-type granules were seen amongst tumour cells. These relatively benign leiomyomas shared some morphologic features with human gastric leiomyomas. Their cause and prognosis remain unknown.

Tungstic acid reduction of cold-resistant stress-induced ulceration in rats.

Sprague‐Dawley rats were restrained at 4°C for 2 h (stress). Tungstic acid in a single dose of 0.01, 0.1, 1, 10, 100 or 300 mg/kg (dissolved in distilled water) was administered intragastrically to animals 30 min prior to stress. Stress induced significant gastric mucosal damage, whereas tungstic acid pretreatment dose‐dependently reduced lesion formation. Doses of tungstic acid of 1 mg/kg and higher significantly (P < 0.05–0.001) decreased ulcers. The mucosal mast cell counts in rats pretreated with tungstic acid were significantly higher than those of control rats. In motility experiments using oral administration of amberlite pellets, pretreatment with tungstic acid dose‐dependently reduced the gastric emptying rate during a 1 h period of stress. Gastric mucosal xanthine oxidase and superoxide dismutase (SOD) activities, after pretreatment with a single dose of tungstic acid, were not altered in stressed animals. It is suggested that tungstic acid effectively antagonizes stress‐induced gastric ulcers, possibly by decreasing motility and mass cell degranulation. Xanthine oxidase and SOD activities and mucous content were not changed in the gastric mucosa by the present method of tungstic acid administration.

Cellular pathology of experimental colitis induced by trinitrobenzenesulphonic acid (TNBS): protective effects of recombinant human interleukin-11.

The objective of this study was to elucidate colonic mucosal ultrastructural effects of trinitrobenzene-sulphonic acid (TNBS) with and without co-administration of recombinant human interleukin-11 (rhIL-11). Using a standard colitis model (ir alcoholic TNBS), rats were sacrificed at 3~14 days after TNBS. Co-administration of rhIL-11 (100, 300 or 1000 μg/kg sc) was given for protection, and controls received saline or alcohol ir, or rhIL-11 sc alone. Transmission electron microscopy revealed that early TNBS-induced cytopathology was primarily in absorptive cells, changes which occurred prior to goblet cell damage. Progressive cellular changes included vacuolization and increased multivesicular bodies in cell apices, disconfiguration of microvilli, enlarged Golgi apparatuses, enlargement of basal inter-cellular spaces, and eventual desquamation of epithelium and apical bursting.Organelle damage preceded surface changes and resembled ultrastructural changes reported for human ulcerative colitis. The principal effect of rhIL-11 was apparent massive release of mucus from goblet cells, filling the colonic crypts, and suggesting a mode of its protection.