Osteoclastogenesis is influenced by modulation of gap junctional communication with antiarrhythmic peptides.

Osteoclasts are formed by the fusion of mononuclear precursor cells of the monocyte-macrophage lineage. Among several putative mechanisms, gap-junctional intercellular communication (GJC) has been proposed to have a role in osteoclast fusion and bone resorption. We examined the role of GJC in osteoclastogenesis and in vitro bone resorption with mouse bone marrow hematopoietic stem cells and RAW 264.7 cells. Blocking of gap junctions with 18-α-glycyrrhetinic acid (18GA) led to inhibition of osteoclastogenesis and in vitro bone resorption. Similarly, the GJC inhibitor GAP27 inhibited osteoclast formation. GJC modulation with the antiarrhythmic peptides (AAPs) led to increased amounts of multinuclear RAW 264.7 osteoclasts as well as increased number of nuclei per multinuclear cell. In the culture of bone marrow hematopoietic stem cells in the presence of bone marrow stromal cells AAP reduced the number of osteoclasts, and coculture of MC3T3-E1 preosteoblasts with RAW 264.7 macrophages prevented the action of AAPs to promote osteoclastogenesis. The present data indicate that AAPs modulate the fusion of the pure culture of cells of the monocyte-macrophage lineage. However, the fusion is influenced by GJC in cells of the osteoblast lineage.

A comparative electron microscopic study of bone repair after internal fracture, osteotomy, and perforation of rat tibia.

BACKGROUND AND OBJECTIVE. Although previous studies have provided new information on bone repair, there are still gaps in knowledge about resorptive and formative processes during bone repair at the electron microscopic level. The aim of this study was to compare bone repair after the internal fracture, osteotomy, and bicortical perforation of the tibia by means of electron microscopy. MATERIAL AND METHODS. An electron microscopic study of bone repair after the internal fracture, osteotomy, and bicortical perforation of the tibia was performed on 72 male Wistar rats. Rats undergoing osteotomy and perforation were further subdivided into the control and immobilization subgroups. Bone repair was observed during the first posttraumatic weeks. RESULTS. Although bone repair in general had similar bone healing stages in all the groups, the repair process depended on the mode and degree of injury thus being different in the experimental groups. After the internal fracture, indirect ossification was observed; after osteotomy, primary periosteal, secondary endosteal ossification was noted; and after perforation, primary endosteal, secondary periosteal ossification was documented. Immobilization had an inhibitory effect on bone repair. CONCLUSIONS. The results of the present study gave new information at the electron microscopic level about intracellular changes and intercellular matrix synthesis during different types of posttraumatic bone repair and confirmed our previous reports on similar posttraumatic bone repair in histomorphometric and immunohistochemical studies.

Gastrin and somatostatin enteroendocrine cells in the small intestines of ostrich (Struthio camelus var. domesticus) during pre -and post-hatching period.

Studies on localization and distribution of enteroendocrine cells (EECs) are important for better understanding of their role in the ontogenetic development of intestines. Information about the distribution of the most important endocrine cells in the digestive tract of the ostrich is very limited; therefore, the aim of the present study was to identify gastrin and somatostatin EECs in the small intestine of the ostrich (Struthio camelus var. domesticus) chicks at different ages. Six embryos along with 42 ostriches of both sexes from hatching up to 60 days post-hatching, including six embryos, were obtained from an ostrich farm in Latvia. Duodenum, jejunum and ileum were investigated using routine histology and immunohistochemistry methods. Gastrin and somatostatin EECs were examined in 10 microscopic fields of the intestinal mucosa in each tissue sample. The cells were detected in all age groups as well as the embryos. The number of both types of EEC in the mucosa of the ileum was significantly lower (p < .01-.05) than in the duodenum. The present study suggested that the EEC may have a role in the development of the mucosa of the intestinal tract of ostriches with possible involvement in the development of the digestive functions.

[Anatomists in the anatomical theater of Tartu (Dorpat) University].

In 1632, King Gustav II Adolphus of Sweden founded Academia Gustaviana,the predecessor of the present Tartu University in Estonia. After the reopening of the University in 1802, the development of the Faculty of Medicine started. The number of outstanding anatomists; Burdach, von Baer, Reichert, Bidder, Reissner, Kupffer, and Rauber made various discoveries at the Anatomical Theater (Theatrum Anatomicum). The present paper acquaints readers with profiles of these anatomists and their main contributions, and attempts to consider reasons of a quick development of Tartu University during rather a short period in the 19th century.

Immunohistochemical Study of Glucose Transporter GLUT-5 in Duodenal Epithelium in Norm and in T-2 Mycotoxicosis.

Although patterns of glucose transporter expression and notes about diseases leading to adaptive changes in intestinal fructose transport have been well-characterized, the connection between infection and fructose transportation has been lightly investigated. Up to now only few studies on GLUT-5 expression and function under pathological conditions in bird intestines have been carried out. The aim of our current research was to immunolocalize GLUT-5 in chicken duodenal epithelium in norm and during T-2 mycotoxicosis. Material from chicken (Gallus gallus domesticus) duodenum was collected from twelve seven-day-old female broilers, divided into control group and broilers with T-2 mycotoxicosis. The material was fixed with 10% formalin and thereafter embedded into paraffin; slices 7 µm in thickness were cut, followed by immunohistochemical staining, according to the manufacturers guidelines (IHC kit, Abcam, UK) using polyclonal primary antibody Rabbit anti-GLUT-5. Our study revealed the strong expression of GLUT-5 in the apical parts of the duodenal epithelial cells in the control group chickens and weak staining for GLUT-5 in the intestinal epithelium in the T-2 mycotoxicosis group. Our results confirmed decreased the expression of GLUT-5 in the duodenal epithelium during T-2 mycotoxicosis.

Application of Photoshop-based image analysis and TUNEL for the distribution and quantification of dexamethasone-induced apoptotic cells in rat thymus.

UNLABELLED: The aim of the present study was to determine the target site cells in the rat thymus after exposure to the synthetic glucocorticoid, dexamethasone, at therapeutic doses. The findings of histology and histochemistry (Feulgen, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling--TUNEL) with quantification by computerized histomorphometry are described. MATERIAL AND METHODS: A quantified investigation of apoptotic and mitotic thymic lymphocytes in 36 young adult Wistar rats was performed at 1-7 days after a 3-day injection of dexamethasone (a total dose of 1.2 mg/rat intraperitoneally). RESULTS: At the first day after dexamethasone administration the moderate involution and atrophy of thymus histology were observed with simultaneous fall in cortical cellularity and mitotic activity of thymocytes. More rapid fall appeared in the inner cortex. The number of apoptotic (TUNEL-positive) cells was significantly increased. On the days 5 and 7 the expression of apoptosis and the cell proliferation were at almost normal level. CONCLUSIONS: The findings suggest that dexamethasone-induced apoptosis of cortical thymic lymphocytes, mainly correlated with synchronous inhibition of mitosis and cell number fall in thymus. The main target sites of dexamethasone injury were cells in the inner cortex of lobuli thymi.

Transport proteins in rats' renal corpuscle and tubules.

UNLABELLED: The localization of transepithelial transport proteins for glucose and water reabsorption in renal corpuscle and tubules epithelium was observed. MATERIAL AND METHODS: Immunohistochemistry of normal male Wistar rats' kidney has been performed. Facilitated diffusion glucose transporter GLUT4, Na(+)-dependent glucose co-transporter SGLT1, a cargo transporter TGN38, and water transporter aquaporin-2 (AQP2) were used. RESULTS: An intensive GLUT4 expression in renal proximal tubules and in convoluted segment of distal tubules has been observed. The intensive SGLT1 expression was marked in all renal tubules, and also in the glomerulus of the renal corpuscle. TGN38 was expressed mainly in the S1 of proximal tubules and a bit weaker in the distal tubules. The most intensive AQP2 expression in the proximal tubules and in the thin part of Henle's loop has been detected. In some cases AQP2 expression in the collecting tubules has been observed. The same tubules nephroni are marked heterogeneously. The distribution of transepithelial transport proteins in different parts of nephroni is also greatly heterogeneous because of weak determination of urinary system. CONCLUSION: The comparable transport-proteins distribution with technique of fluorescence immunohistochemistry in rats' renal corpuscle and tubules was elucidated. Data suggest that expression of glucose and water transepithelial transporter proteins is heterogeneous in all parts of nephron, and, probably, is in accordance with recycling of transport proteins.

Callus area and glycosaminoglycans content of the traumatized tibia in rats.

UNLABELLED: The aim of the present work is the quantification of the post-traumatic bone healing histology (total callus morphometry) and histochemistry of the glycosaminoglycans (GAG) content (microspectrometry) in rats tibia after segment osteotomy and bicortical perforation of trained and immobilized animals. MATERIAL AND METHODS: A quantified investigation of post-traumatic bone repair histology and GAG content after osteotomy and perforation of tibia in 105 young adult male Wistar rats has been performed. The repair was studied in normal and affected (training and immobilization) animals at 1-42 days after operation. RESULTS: The posttraumatic bone repair is an ordinary process of osteohisto- and organogenesis, and dependent on the environment factors (mode and degree of trauma, training of animals, etc.). The repair is trauma-dependent; after osteotomy the total callus area is significantly larger respectively to perforation. Otherwise, the training did not significantly influence the repair callus area and GAG content and therefore did not accelerate the bone repair, whereas the immobilization of animals depressed these processes and the bone repair was inhibited. CONCLUSIONS: Quantified study of histology and histochemistry of bone repair after perforation gave important new, more detailed results on the reparative histogenesis of the bone tissues: repair dynamics of callus areas, dynamics of GAG concentration, effects of mode and degree of trauma, training and immobilization on the repair process.

The glucose transporter GLUT1 and the tight junction protein occludin in nasal olfactory mucosa.

The nervous cells in the brain and the peripheral nerves are isolated from the external environment by the blood-brain, blood-cerebrospinal fluid and blood-nerve barriers. The glucose transporter GLUT1 mediates the specific transfer of glucose across these barriers. The olfactory system is unique in that its sensory cells, olfactory receptor neurons, are embedded in the nasal olfactory epithelium and send their axons directly to the olfactory bulb of the brain. Only the apical parts of the olfactory receptor neurons are exposed to the lumen, and these serve as sensors for smell. Immunohistochemical examination showed that the tight junction protein occludin was present in the junctions of the olfactory epithelium. Endothelial cells in the blood vessels in the lamina propria of the olfactory mucosa were also positive for occludin. These observations suggest that the olfactory system is guarded from both the external environment and the blood. GLUT1 was abundant in these occludin-positive endothelial cells, suggesting that GLUT1 may serve in nourishing the cells of the olfactory system. Taken together, GLUT1 and occludin may serve as part of the machinery for the specific transfer of glucose in the olfactory system while preventing the non-specific entry of substances.