Initial wound healing attachments to demineralized dentin.

This report describes the initial in vivo wound healing response of connective tissue components and cells to demineralized and nondemineralized dentin surfaces. Rectangular dentin specimens were prepared from beneath root surfaces covered by periodontal ligament. One group of six specimens were treated with citric acid, while another six specimens served as untreated controls. Specimens were implanted vertically into the skin of rats such that one end of the implant protruded above the skin. After one day, the implants were removed, and the dentin surface-connective tissue interface was examined using scanning electron microscopic methods. The surface of the nondemineralized dentin implants had the morphological characteristics of a surface smear layer. Cells that were present on these nondemineralized surfaces were rounded in shape with few processes or extensions to the dentin surface or to other cells. The surfaces of the demineralized dentin implants were fibrillar in appearance and were usually covered by a layer that had many globular and fibrillar structures attached. Cells that were present on these demineralized surfaces exhibited marked bipolarity with distinct attachments to the dentin surface. Cell processes often extended into the openings of demineralized dentin tubules. It was concluded that an established cellular and connective tissue response to demineralized dentin occurred within the first 24 hours of wound healing, and that this response differed markedly from that associated with nondermineralized dentin surfaces.

Effect of a diabetic state on myometrial ultrastructure and isolated uterine contractions in the rat.

Alterations in rat myometrial ultrastructure and in vivo uterine contractile responses to oxytocin were examined in estradiol-treated (40 micrograms/kg) euglycemic and streptozotocin-induced (85 mg/kg) diabetic rats. Myometrial morphology was examined 18, 24, and 36 hr after estradiol administration. At the time points examined, nuclei of myometrial cells from euglycemic and diabetic rats were pleomorphic and contained large areas of heterochromatin dispersed throughout the nuclei. Mitochondria were round to oval in shape and contained a dense matrix with cristae that extended across the mitochondria. Myofilaments were found in both euglycemic and diabetic cells but the relative number of myofilaments in diabetic cells appeared to be less than the number found in myometrial cells removed from euglycemic animals. The number of free cytoplasmic ribosomes in diabetic cells also appeared to be less than those found in euglycemic cells. In order to determine if apparent differences in the number of myofilament found in diabetic myometrial cells could be correlated with changes in uterine contractile responses to hormones, oxytocin dose-response curves (10(-8) to 10(-5) M) were examined in isolated uteri removed from saline-injected and estradiol-injected (24-hr pretreatments) euglycemic and diabetic rats. The maximal contractile responses (milligrams tension developed per milligrams tissue) in saline-injected euglycemic and diabetic rats were 49 +/- 5 and 36 +/- 4, respectively, while maximal contractile responses in estradiol-injected euglycemic and diabetic rats were 68 +/- 7 and 45 +/- 5, respectively. Maximal contractile responses induced by oxytocin in estradiol-treated diabetic uteri were significantly smaller than the contractile responses measured in euglycemic estradiol-treated uteri. This study demonstrates that estradiol-induced changes in both myometrial cell morphology and in vitro uterine contractile responses to oxytocin are altered in diabetic rats.

Effects of experimentally-induced diabetes on oestradiol-stimulated changes in the ultrastructure of the rat endometrium.

Alterations in endometrial cell morphology following oestradiol treatment of ovariectomized animals were examined in euglycaemic and streptozotocin-induced diabetic rats. Endometrial morphology was examined 18, 24, 36 and 48 h after oestradiol administration. Nuclei of endometrial cells from saline injected euglycaemic and diabetic rats exhibited pleomorphic nuclei with areas of heterochromatin dispersed throughout the nucleus. Nucleoli were homogeneous in appearance and endometrial cells showed no mitotic chromosome function or cell division. The cytoplasm of euglycaemic and diabetic cells contained few mitochondria. The mitochondria that were present contained a uniformly dense matrix and cristae that extended across the mitochondria. The formation of round to oval shaped nuclei with diffuse euchromatin was observed at 18, 24 and 36 h following oestradiol administration in euglycaemic animals. Alterations in nuclear morphology and the formation of euchromatin were absent or reduced at the same time intervals examined in diabetic animals. Nucleoli in oestradiol-treated euglycaemic animals at 18, 24 and 36 h post-injections became very prominent and displayed easily visible granules and fibrillar material. Comparable changes in nucleolar morphology in oestradiol-treated diabetic rats were absent. The development of oval to round mitochondria containing short cristae and an electron-lucent matrix became apparent at 18 h post-injection of oestradiol in euglycaemic control animals. Alterations in mitochondrial morphology did not appear in endometrial cells of oestradiol-treated diabetic animals at any of the time points examined. At 24 and 36 h post-injection of oestradiol in euglycaemic animals, mitotic figures were observed in mitochondrial cells. Cell division and mitotic figures were not observed in oestradiol-treated diabetic animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Cell processes in dentin tubules during early phases of attachment to demineralized periodontitis-affected surfaces.

This report details some preliminary observations regarding cell morphology and behavior during early phases of in vivo attachment to demineralized surfaces. Rectangular dentin specimens prepared from beneath calculus-covered areas of root surfaces were treated with citric acid and implanted vertically into the skin of rats such that one end of the implant protruded above the skin. The implants were removed after 1 day and the dentin surface - connective tissue interface examined using scanning electron microscopy. A dynamic series of biological events seemed to be in progress. Numerous cells were attached to the dentinal root surface. Cell processes extended a considerable distance along the root surface and into dentin tubules. Cell processes in dentin tubules are discussed.

The production of a root surface smear layer by instrumentation and its removal by citric acid.

The purpose of this study was to characterize, using the scanning electron microscope, the nature of root surfaces denuded by (1) root planing alone or (2) root planing plus citric acid treatment. Six teeth were extracted from three squirrel monkeys, and the coronal half of the root surface was planed to remove attached periodontal ligament fibers and cementum. Citric acid, pH 1, was topically applied to the denuded surfaces of 3 teeth. The surface of only root-planed specimens had an irregular surface which corresponded to a smear layer. Root surfaces that had received acid treatment after root planing exhibited funnel-shaped orifices of dentinal tubules, and intertubular zones with a fibrillar, mat-like morphology. The implications of the different root-surface characteristics are discussed.

Local and systemic cell-mediated immunity against transmissible gastroenteritis, an intestinal viral infection of swine.

The occurrence of local and systemic cell-mediated immunity (CMI) in swine against transmissible gastroenteritis (TGE) virus, a coronavirus that infects the epithelial cells of the small intestine of swine, has been investigated. Leukocyte suspensions prepared from intestinal lamina propria (LP) and spleen were each incubated with and without inactivated TGE virus. The supernatants from these cultures were tested for the presence of macrophage migration inhibition factor (MIF) by the indirect MIF test using guinea pig peritoneal exudate cells as the source of macrophages. All swine serologically negative for TGE antibodies (i.e., unexposed to TGE virus) were also negative for MIF production by lymphocytes from both sources. In 10 of 10 animals given TGE virus subcutaneously, MIF production by splenic lymphocytes was significantly greater (p less than or equal to 0.01) than by LP lymphocytes, and in 9 of 10 of these animals MIF production by LP lymphocytes was negligible (percentage of inhibition of migration less than 3%).

Pathogenicity of an attenuated strain of transmissible gastroenteritis virus for newborn pigs.

The pathogenicity of a cell culture-attenuated strain of transmissible gastroenteritis virus for newborn pigs was investigated. Newborn (1- to 2-day-old) pigs were orally given 2 x 10(6) plaque-forming units of attenuated virus. All pigs developed mild diarrhea, but deaths did not occur. As determined by immunofluorescence and villous atropy, infection of the small intestine was limited to the caudal 50 to 66%. Fluorescing cells and atrophic villi were seen from 2 to 3 days until 6 to 7 days after exposure. Attenuated virus-exposed pigs produced circulating virus-neutralizing antibodies detectable as early as 5 days after exposure. By contrast, all pigs orally given 1 x 10(2) pig infective doses of virulent transmissible gastroenteritis virus developed severe diarrhea, and almost all of those not killed died within 2 to 5 days after exposure. In the latter pigs, the entire length of the small intestine, except for the first 4 to 5 cm, was infected with virus by 24 to 36 hours after exposure.