Mechanisms of bone remodeling and therapeutic strategies in chronic apical periodontitis.

Chronic periapical periodontitis (CAP) is a typical oral disease in which periodontal inflammation caused by an odontogenic infection eventually leads to bone loss. Uncontrolled infections often lead to extensive bone loss around the root tip, which ultimately leads to tooth loss. The main clinical issue in the treatment of periapical periodontitis is the repair of jawbone defects, and infection control is the first priority. However, the oral cavity is an open environment, and the distribution of microorganisms through the mouth in jawbone defects is inevitable. The subversion of host cell metabolism by oral microorganisms initiates disease. The presence of microorganisms stimulates a series of immune responses, which in turn stimulates bone healing. Given the above background, we intended to examine the paradoxes and connections between microorganisms and jaw defect repair in anticipation of new ideas for jaw defect repair. To this end, we reviewed the microbial factors, human signaling pathways, immune cells, and cytokines involved in the development of CAP, as well as concentrated growth factor (CGF) and stem cells in bone defect repair, with the aim of understanding the impact of microbial factors on host cell metabolism to inform the etiology and clinical management of CAP.

Effects of glycyl-glutamine dipeptide supplementation on myocardial damage and cardiac function in rats after severe burn injury.

Glutamine decreases myocardial damage in ischemia/reperfusion injury. However, the cardioprotective effect of glutamine after burn injury remains unclear. Present study was to explore the protective effect of glycyl-glutamine dipeptide on myocardial damage in severe burn rats. Seventy-two Wistar rats were randomly divided into three groups: normal control (C), burned control (B) and glycyl-glutamine dipeptide-treated (GG) groups. B and GG groups were inflicted with 30% total body surface area of full thickness burn. The GG group was given 1.5 g/kg glycyl-glutamine dipeptide per day and the B group was given the same dose of alanine via intraperitoneal injection for 3 days. The serum CK, LDH, AST, and, blood lactic acid levels, as well as the myocardium ATP and GSH contents, were measured. The indices of cardiac contractile function and histopathological change were analyzed at 12, 24, 48, and 72 post-burn hours (PBH). The serum CK, LDH, AST and blood lactic acid levels increased, and the myocardium ATP and GSH content decreased in both burned groups. Compared with B group, the CK, LDH, AST and blood lactic acid levels reduced, myocardium ATP and GSH content increased in GG group. Moreover, the inhibition of cardiac contractile function and myocardial histopathological damage were reduced significantly in GG group. We conclude that myocardial histological structure and function were damaged significantly after burn injury, glycyl-glutamine dipeptide supplementation is beneficial to myocardial preservation by improving cardiocyte energy metabolism, increasing ATP and glutathione synthesis.

Effects of glycine supplementation on myocardial damage and cardiac function after severe burn.

BACKGROUND: Glycine has been shown to participate in protection from hypoxia/reoxygenation injury. However, the cardioprotective effect of glycine after burn remains unclear. This study aimed to explore the protective effect of glycine on myocardial damage in severely burned rats. METHODS: Seventy-two Wistar rats were randomly divided into three groups: normal controls (C), burned controls (B), and glycine-treated (G). Groups B and G were given a 30% total body surface area full-thickness burn. Group G was administered 1.5 g/(kg d) glycine and group B was given the same dose of alanine via intragastric administration for 3d. Serum creatine kinase (CK), lactate dehydrogenase (LDH), aspartate transaminase (AST), and blood lactate, as well as myocardial ATP and glutathione (GSH) content, were measured. Cardiac contractile function and histopathological changes were analyzed at 12, 24, 48, and 72 hours. RESULTS: Serum CK, LDH, AST, and blood lactate increased, while myocardial ATP and GSH content decreased in both burned groups. Compared with group B, the levels of CK, LDH, and AST significantly decreased, whereas blood lactate as well as myocardial ATP and GSH content increased in group G. Moreover, cardiac contractile function inhibition and myocardial histopathological damage in group G significantly decreased compared with group B. CONCLUSION: Myocardial histological structure and function were damaged significantly after burn. Glycine is beneficial to myocardial preservation by improving cardiomyocyte energy metabolism and increasing ATP and GSH abundance.

Effects of glutamine treatment on myocardial damage and cardiac function in rats after severe burn injury.

Treatment with glutamine has been shown to reduce myocardial damage associated with ischemia/reperfusion injury. However, the cardioprotective effect of glutamine specifically after burn injury remains unclear. The present study explores the ability of glutamine to protect against myocardial damage in rats that have been severely burned. Seventy-two Wistar rats were randomly divided into three groups: normal controls (C), burned controls (B) and a glutamine-treated group (G). Groups B and G were subjected to full thickness burns comprising 30% of total body surface area. Group G was administered 1.5 g/ (kg•d) glutamine and group B was given the same dose of alanine via intragastric administration for 3 days. Levels of serum creatine kinase (CK), lactate dehydrogenase (LDH), aspartate transaminase (AST) and blood lactic acid were measured, as well as myocardial ATP and glutathione (GSH) contents. Cardiac function indices and histopathological changes were analyzed at 12, 24, 48 and 72 post-burn hours. In both burned groups, levels of serum CK, LDH, AST and blood lactic acid increased significantly, while myocardial ATP and GSH contents decreased. Compared with group B, CK, LDH, and AST levels were lower and blood lactic acid, myocardial ATP and GSH levels were higher in group G. Moreover, cardiac contractile function inhibition and myocardial histopathological damage were significantly reduced in group G compared to B. Taken together, these results show that glutamine supplementation protects myocardial structure and function after burn injury by improving energy metabolism and by promoted the synthesis of ATP and GSH in cardiac myocytes.

[Effects of intestinal trefoil factor combined with mucin on immune function of burn serum treated intestinal epithelial cells].

OBJECTIVE: To observe the effect of intestinal trefoil factor (ITF) combined with mucin on immune function of intestinal epithelial cells (IEC) after being treated with burn rat serum. METHODS: The rat IEC-6 cell lines were divided into control group (C, cultured in DEME medium containing 10% calf serum), burn control group (BC, cultured in DEME medium containing 10% burn rat serum), burn serum + ITF group (B + I, cultured in DEME medium containing 10% burn rat serum and 25 microg/mL ITF), burn serum + mucin group (B + M, cultured in DEME medium containing 10% burn rat serum and 250 microg/mL mucin), and burn serum + ITF + mucin group (B + I + M, cultured in DEME medium containing 10% burn rat serum, 25 microg/mL ITF, and 250 microg/mL mucin) according to the random number table. Meanwhile, 200 microL suspension of E. coli with density of 1 x 10(8) CFU/mL was added to each culture. At post culture minute (PCM) 15, 30 and post culture hour (PCH) 1, 2, 3, the number of bacteria adherent to IEC-6 was counted after Wright-Giemsa staining, and cell survival rate was calculated after trypan blue staining, with 20 samples in each group at each time point. (2) Other samples of IEC-6 cells without addition of E. coli were divided into BC, B + I, B + M, and B + I + M groups with the same treatment as above. The supernatant contents of IL-6, IL-8, and TNF-alpha were determined by radioimmunoassay at PCH 3, 6, 12, 24, 48, with 6 samples in each group at each time point. Data were processed with t test. RESULTS: (1) Compared with that in C group, count of adherent bacteria to IEC-6 in BC group at each time point was significantly increased (with t values from 2.947 to 8.149, P values all below 0.01). Compared with those in BC group, the counts in B + I, B + M, B + I + M groups at the major time points were significantly decreased (with t values from -4.733 to -2.180, P < 0.05 or P < 0.01). (2) Compared with that in C group, cell survival rate in BC group at each time point was obviously lowered (with t values from -4.126 to -2.363, P values all below 0.05). Cell survival rates in B + I and B + M groups at some time points were significantly elevated as compared with those in BC group (with t values from 2.120 to 3.423, P < 0.05 or P < 0.01). Cell survival rate in B + I + M group at PCM 15 and PCH 3 was respectively (96.7 +/- 2.4)% and (84.0 +/- 6.7)%, which was respectively higher than that in B + I and B + M groups [(94.5 +/- 3.1)%, t = 2.507, P < 0.05; (77.1 +/- 8.2)%, t = 2.934, P < 0.01]. (3) The contents of TNF-alpha in supernatant of B + I + M group at PCH 6, 12, 24, 48 were significantly lower than those in the other 3 groups (with t values from -6. 914 to -2.889, P < 0.05 or P < 0.01). The contents of IL-6 in supernatant of B + I + M group at some time points were significantly lower than those in the other 3 groups (with t values from -7. 657 to -2.580, P < 0.05 or P < 0.01). The contents of IL-8 in supernatant of B + I + M group at PCH 6, 12, 24, 48 were significantly lower than those in BC and B + M groups (with t values from - 8.802 to - 3.640, P values all below 0.01), and those in B + I + M group at PCH 12, 24 were lower than those in B + I group (with t value respectively -2.786, -2.740, P value all below 0.05). CONCLUSIONS: ITF can maintain immune function and homeostasis of IEC, prevent bacterial adherence, decrease cell death rate, and reduce release of inflammatory mediators. The effect can be strengthened with addition of mucin.

[Effects of intestinal trefoil factor combined with mucin on ability of proliferation and migration of intestinal epithelial cells after being treated by rat burn serum].

OBJECTIVE: To observe the effect of intestinal trefoil factor (ITF) combined with mucin on the ability of proliferation and migration of intestinal epithelial cells (IEC) after being treated by burn rat serum. METHODS: The rat IEC-6 cell lines were subcultured and divided into control group (C, cultured with DMEM medium containing 10% calf serum), burn serum group (BS, cultured with DMEM medium containing 10% burn rat serum), burn serum + ITF group (B + I, cultured with DMEM medium containing 10% burn rat serum and 25 microg/mL ITF), burn serum + mucin group (B + M, cultured with DMEM medium containing 10% burn rat serum and 250 microg/mL mucin), and burn serum + ITF + mucin group (B + I + M, cultured with DMEM medium containing 10% burn rat serum, 25 microg/mL ITF, and 250 microg/mL mucin) according to the random number table. Cells were counted on post culture day (PCD) 0, 1, 2, 3, 4, reflecting cell proliferation ability. Cell migration distance was measured at post scratch hour (PSH) 12, 24, 36, 48, 72. Then, cells of each group were placed in upper compartment of Transwell chamber while the corresponding medium was respectively added into lower compartment of Transwell chamber. Cells in lower compartment of Transwell chamber were counted at post culture hour (PCH) 4, 6, 8, 10, 12, reflecting cytomorphosis ability. Data were processed with t test. RESULTS: (1) Cell proliferation ability. The cell numbers in BS group on PCD 0, 1, 2, 3, 4 were significantly less than those in C group (with t values from -16.569 to -2.613, P < 0.05 or P < 0.01). The cell number showed no statistical difference between B + I and BS groups, and between B + M and BS groups at each time point (with t values respectively from 0.037 to 0.740 and 0.116 to 0.429, P values all above 0.05). The cell number in B + I + M group on PCD 2 was respectively larger than that in BS group (t = 6.484, P < 0.01) and B + I group ( t = 3.838, P < 0.01). (2) Cell migration distance in BS group at PSH 12, 24, 36, 48, 72 was significantly shorter than that in C group (with t values from -37.594 to -6.727, P values all below 0.01). There was no obvious difference in cell migration distance between BS and B + M groups at each time point (with t values from 0.055 to 0.589, P values all above 0.05). Cell migration distance in B + I group at PSH 12, 24, 36 was respectively (47 +/- 6), (126 +/- 13), (170 +/- 11) microm, all longer than those in BS group [(42 +/- 7), (98 +/- 14), (154 +/- 22) microm, with t values from 2.230 to 4.817, P < 0.05 or P < 0.01]. Cell migration distance in BS group at PSH 12, 24, 36, 48, 72 and B + I group at PSH 12, 24, 36, 48 was respectively shorter than that in B + I + M group (with t values respectively from 2.982 to 7.390 and 2.707 to 2.918, P < 0.05 or P < 0.01). (3) Cytomorphosis ability. Compared with those of C group, cell counts in lower compartment of BS group at PCH 4, 6, 8, 10, 12 were significantly decreased (with t values from -23.965 to -6.436, P values all below 0.01). Cell count in lower compartment of BS group at PCH 4, 6, 8, 10, 12 was respectively less than that of B + I group (with t values from 3.650 to 10.028, P values all below 0.01) and similar to that of B + M group (with t values from 0.199 to 0.797, P values all above 0.05). Cell counts in lower compartment of B + I + M group at PCH 4, 6, 8, 10, 12 were significantly larger than those of BS group (with t values from 4.313 to 15.100, P values all below 0.01). Cell count in lower compartment of B + I + M group at PCH 10 (328 +/- 47) and PCH 12 (465 +/- 37) was respectively larger than that in B + I group (277 +/- 25, 353 +/- 34, with t value respectively 3.051, 6.945, P values all below 0.01). CONCLUSIONS: ITF can improve cytomorphosis ability for promoting cell migration with limited effect on cell proliferation, which can be enhanced with addition of mucin. The main mechanism of ITF in maintaining intestinal mucosal barrier may be attributed to acceleration of cell migration.