UPLC-MS/MS Assay for Quantification of Wedelolactone and Demethylwedelolactone in Rat Plasma and the Application to a Preclinical Pharmacokinetic Study.

AIMS AND OBJECTIVE: Wedelolactone and demethylwedelolactone are the two major coumarin constituents of Herba Ecliptae. The objective of this work was to develop and validate a sensitive, rapid, and robust UPLC-MS/MS method for the simultaneous quantification of wedelolactone and demethylwedelolactone in rat plasma. MATERIALS AND METHODS: Wedelolactone and demethylwedelolactone were extracted from rat plasma by protein precipitation with acetonitrile. Electrospray ionization in negative mode and selected reaction monitoring (SRM) were used for wedelolactone and demethylwedelolactone at the transitions m/z 312.8→298.0 and m/z 299.1→270.6, respectively. Chromatographic separation was conducted on a Venusil C18 column (50 mm × 2.1 mm, 5 µm) with isocratic elution of acetonitrile-0.1% formic acid in water (55:45, v/v) at a flow rate of 0.3 mL/min. A linear range was observed over the concentration range of 0.25-100 ng/mL for wedelolactone and demethylwedelolactone. RESULTS: They reached their maximum plasma concentrations (Cmax, 74.9±13.4 ng/mL for wedelolactone and 41.3±9.57 ng/mL for demethylwedelolactone) at the peak time (Tmax) of 0.633 h and 0.800 h, respectively. The AUC0-t value of wedelolactone (260.8±141.8 ng h/mL) was higher than that of demethylwedelolactone (127.4±52.7 ng h/mL) by approximately 2-fold, whereas the terminal elimination half-life (t1/2) of wedelolactone (2.20±0.59 h) showed the approximately same as that of demethylwedelolactone (2.08±0.69 h). CONCLUSION: Based on full validation according to US FDA guidelines, this UPLC-MS/MS method was successfully applied to a pharmacokinetic study in rats.

[Analysis of influencing factors of high-frequency hearing loss among male noise workers in an automobile manufacturing enterprise].

Objective: To analysis of high-frequency hearing loss status and risk factors among male noise workers in an automobile manufacturing enterprise in Guangzhou. Methods: From February 2020, a cluster sampling method was used to select 3486 male workers exposed to noise in an automobile manufacturing enterprise in Guangzhou in 2018. After screening, 2608 were selected as the research objects. Pure tone hearing threshold test, noise exposure level test and questionnaire survey were conducted, and the cumulative noise exposure was calculated. Chi square test and unconditional logistic regression were used to analyze the correlation between various factors and high frequency hearing loss. Results: The detection rate of high-frequency hearing loss in noise exposed workers was 34.20% (892/2608) , there were significant differences in the two groups among age, marital status, years of noise exposure, noise exposure equivalent A sound level, CNE, different working hours and exposure to electromagnetic radiation (P<0.05) . Multiple logistic regression analysis showed that age, CNE and exposure to electromagnetic radiation were independent risk factors for high-frequency hearing loss (P<0.05) , three shifts and two shifts were the protective factors for the occurrence of high-frequency hearing loss (OR=0.523, P<0.01) . Conclusion: Noise exposure is the main influencing factor of high-frequency hearing loss of noise-receiving workers in automobile manufacturing enterprises. Enterprises should strengthen noise control in the workplace, improve the working environment of electromagnetic radiation, and implement a scientific and healthy work shift system.

Gingko biloba extract EGB761 alleviates heat-stress damage in chicken heart tissue by stimulating Hsp70 expression in vivo in vascular endothelial cells.

1. This study aimed to investigate the protective effects of Gingko biloba extract EGB761 on heat-stressed chicken heart in vivo and its underlying relevance to Hsp70.2. A total of 50 one-day-old female chicks were randomly divided into five groups: control (Con), heat-stress (HS), 0.1% EGB761 plus heat-stress (0.1%EGB+HS), 0.3%EGB761 plus heat-stress (0.3%EGB+HS) and 0.6%EGB761 plus heat-stress (0.6%EGB+HS) groups. After administration of EGB761 for 45 days, the chickens in each group were exposed to a single heat-stress event at 38 ± 1°C for 3 h.3. EGB761 attenuated the abnormal symptoms and pathological scores of myocardium of heat-stressed chickens. Despite a reduction in the transcription and translation of the Hsp70 gene in heat-stressed myocardium, EGB761 induced the expression of Hsp70 in endothelial cells of the microarteries and venules into the blood, and reduced heat-stress damage in vascular endothelial cells.4. Supplementation with EGB761 before heat-stress exposure protected chicken myocardium from damage by increasing serum Hsp70 protein from myocardial cells and cardiac microvascular endothelial cells and protected the microvascular system from adverse injury.

Inhibition of heat stress-related apoptosis of chicken myocardial cells through inducing Hsp90 expression by aspirin administration in vivo.

1. This experiment investigated the anti-apoptosis effects and the mechanism of aspirin action in the heat shock response of chicken myocardial cells in vivo, via changes in the heat stress (HS) protein Hsp90 and the rate of apoptosis. Broiler chickens were administered aspirin (1 mg/kg body weight) 2 h before exposure to HS, and then exposed to 40 ± 1°C for 0, 1, 2, 3, 5, 7, 10, 15 and 24 h. 2. The induction and consumption of the HS factor heat shock factor (HSF)-1, and reductions of HSF-2 and HSF-3 induced by HS led to a delay in Hsp90 expression. HSF-1, 2 and 3 regulation of hsp90 expression in turn inhibited the synthesis and activation of protein kinase ß (Akt), which resulted in a significant increase in caspase-3 at 2 and 10 h, caspase-9 from 1 to 7 h (except at 5 h), and the heat-stressed apoptosis of the myocardial cells. 3. Administration of aspirin changed the expression patterns of HSF-1, 2 and 3 such that the expression of Hsp90 protein was significantly upregulated (by 2.3-4.1 times compared with that of the non-treated cells). The resultant increase in Akt expression and activation, compared with the HS group, inhibited caspase-3 and caspase-9 activities and reduced the myocardial cells apoptosis rate (by 2.14-2.56 times). 4. Aspirin administration could inhibit heat-stressed apoptosis of myocardial cells in vivo and may be closely associated with its promotion of HS response of chicken hearts, especially Hsp90 expression.

Hsp70 expression induced by Co-Enzyme Q10 protected chicken myocardial cells from damage and apoptosis under in vitro heat stress.

The aim of this study was to investigate whether induction of Hsp70 expression by co-enzyme Q10 (Q10) treatment protects chicken primary myocardial cells (CPMCs) from damage and apoptosis in response to heat stress for 5 hours. Analysis of the expression and distribution of Hsp70 and the levels of the damage-related enzymes creatine kinase-MB (CK-MB) and lactate dehydrogenase (LDH), as well as pathological analysis showed that co-enzyme Q10 alleviated the damage caused to CPMCs during heat stress. Further, analysis of cell apoptosis and the expression of cleaved caspase-3 indicated that co-enzyme Q10 did have an anti-apoptotic role during heat stress. Western blot analysis showed that pretreatment with co-enzyme Q10 led to a significant increase in the expression of Hsp70 during heat stress. Immunostaining assays confirmed the results of western blot analysis and also showed that co-enzyme Q10 could accelerate the translocation of Hsp70 into the nucleus during heat stress, but this was not observed in the group that was treated with only co-enzyme Q10. These findings seem to indicate that co-enzyme Q10 protected CPMCs from heat stress via the induction of Hsp70. To investigate this, 200 µM quercetin, an Hsp70 inhibitor, was used to inhibit the expression of Hsp70 2 h before heat stress. Quercetin pre-treatment was observed to suppress the expression of Hsp70 as well the protective function of co-enzyme Q10 at 5 h of heat stress. This finding confirms that Q10 brought about its effects via Hsp70 expression, but the mechanism underlying this needs further investigation.

ACTH-induced stress in weaned sows impairs LH receptor expression and steroidogenesis capacity in the ovary.

BACKGROUND: Stress has been proved to impair the porcine reproduction soundly. Endocrine disruption, which is closely related to the persistent follicles, is possibly one of the results of stress, although the mechanism is unclear. Since the expression of luteinizing hormone receptor (LHR) in ovarian follicular wall and concentrations of steroid hormone in follicular fluid are related to the development of persistent follicles, this study is designed to evaluate the effect of administered adrenocorticotrophic hormone (ACTH) to weaned pigs on their ovarian steroidogenesis capacity and LHR expression. METHODS: Ten multiparous sows were weaned and randomly divided into two groups (n = 5 each). Sows received 1 IU/kg ACTH (ACTH group) or saline (control group) every 8 h from days 3-9 after jugular vein intubation. Blood samples were collected throughout the experiment, and ovaries were collected after slaughter on day 10. Follicular fluid (FF) was used to determine the steroid hormone concentrations. The ovarian follicle wall was obtained and stored in liquid nitrogen to detect mRNA levels. RESULTS: The plasma cortisol concentration was significantly (P < 0.01) elevated after ACTH injection. The estradiol (E2) and androstenedione (ASD) concentrations in FF were significantly lower (P < 0.05) in the ACTH group than in the control group. The LHR, 3ß-hydroxysteroid dehydrogenase (3ß-HSD), cytochrome P450 aromatase (P450arom), and cytochrome P450 17a-hydroxylase (P450c17) mRNA levels were significantly (P < 0.05) reduced in the ACTH group. The steroidogenic acute regulatory protein (StAR) level and cytochrome P450 side-chain cleavage (P450scc) was lower in the ACTH group than in the control group, but the difference was not statistically significant (P > 0.05). Immunostaining results revealed 3ß-HSD,P450c17, and LHR expression in theca cells, and P450arom expression in granulosa cells. Immunohistochemical staining showed significant differences in the distribution of 3ß-HSD, P450c17, LHR, and P450arom between the two groups. CONCLUSIONS: These findings indicated that ACTH significantly diminished the LHR expression and steroidogenesis capacity of the ovaries of weaned sows.

Mixture of polysaccharide and nucleic acid extracted from Bacillus Calmette-Guerin (BCG) enhances immune response of infectious bursal disease virus vaccine in chickens.

In this study, the immune response induced by a mixture of polysaccharide and nucleic acid extracted from Bacillus Calmette-Guerin (BCG) was evaluated in chickens inoculated with infectious bursal disease virus (IBDV) vaccine. After the mixture was injected intramuscularly at a dose of 0.075, 0.15 or 0.3 mg·kg(-1)·day(-1) for 3 days, the 14-day-old chickens were inoculated with the attenuated IBDV vaccine via intranasal and ocular routes. The relative weight of bursa of Fabricius (BF) and thymus, the serum IBD antibody titer, the CD4+/CD8+ ratio, and the concentrations of IFN-γ, IL-2 and IL-6 in peripheral blood were investigated on days 5, 15 and 25. The IBD antibody titer in BCG-treated groups was higher than in the negative control and only IBD-vaccinated chickens, indicating that the mixture of BCG can significantly enhance chicken humoral response. CD4+/CD8+ and the secretions of IFN-γ, IL-2 and IL-6 were also clearly increased compared with that in the negative control and IBD-vaccinated chickens, indicating that the mixture can also enhance the cell-mediated immune response. The results also showed that the relative weights of BF and thymus increased after chickens were inoculated with BCG, indicating that the BCG mixture can clearly enhance the immunity of IBD-vaccine and can be expected to be viewed as a candidate for a new type of immune adjuvant.

HSP90 gene expression induced by aspirin is associated with damage remission in a chicken myocardial cell culture exposed to heat stress.

To understand the potential protection of heat shock protein 90 (HSP90) induced by aspirin against heat stress damage in chicken myocardial cells, enzyme activities related to stress damage, cytopathological changes, the expression and distribution of HSP90, and HSP90 mRNA levels in the myocardial cells exposed to heat stress (42°C) for different durations with or without aspirin administration (1 mg/ml, 2 h prior) in vitro were investigated. Significant increase of enzyme levels in the supernatant of heat-stressed myocardial cells and cellular lesions characterised by acute degeneration, karyopyknosis and karyorrhexis were observed, compared to non-treated cells. However, the lesions of cells treated with aspirin were milder, characterised by earlier recovery of enzyme levels to the control levels and no obvious heat stress-related cellular necrosis. Stronger positive signals in the cytoplasm and longer retention of HSP90 signal in nuclei were observed in aspirin-treated myocardial cells than those of only heat-stressed cells. HSP90 level in the aspirin-treated myocardial cells was 11.1-fold higher than that in non-treated cells, and remained at a high level at the early stage of heat stress, whereas it was just 4.1-fold higher in only heat-stressed cells and returned rapidly to a low level. Overexpression of HSP90 mRNA in aspirin-treated cells was observed throughout the experiment, whereas HSP90 mRNA decreased significantly only in heat-stressed cells. The early higher HSP90 expression induced by aspirin during heat stress was accompanied by decreased heat stress damage, suggesting that aspirin might play an important role in preventing myocardial cells from heat stress damage in vitro.

Association of heat shock protein 70 expression with rat myocardial cell damage during heat stress in vitro and in vivo.

To investigate the mechanism of sudden death as a result of stress-induced damage to heart tissue and myocardial cells and to investigate the cardioprotective role of Hsp70 during heat stress, the distribution and expression of Hsp70 was evaluated in the heart cells of heat-stressed rats in vivo and heat-stressed H9c2 cells in vitro. After exposure to heat stress at 42°C for different durations, we observed a significant induction of CK, CK-MB, and LDH as well as pathologic lesions characterized by acute degeneration, suggesting that cell damage occurs from the onset of heat stress. Immunocytochemistry showed that Hsp70 was distributed mainly in the cytoplasm of myocardial cells in vivo and in vitro. Hsp70-positive signals in the cytoplasm were more prominent in intact areas than in degenerated areas after 60 min of heat stress. Hsp70 protein levels in myocardial cells in vitro decreased from the beginning to the end of heat stress. Hsp70 protein levels in rat heart tissues in vivo decreased gradually with prolonged heat stress, with a slight increase at the beginning of heat stress. These results indicate that Hsp70 plays a role in the response of cardiac cells to heat stress and that decreased Hsp70 levels are associated with damage to rat myocardial cells in vitro and in vivo. Significant differences were found in hsp70 mRNA, which began to increase after 20 min of heat stress in vitro and after 40 min in vivo. This indicates that hysteresis is involved in mRNA expression after heat stress in vivo.

Evaluation of Hsp47 expression in heat-stressed rat myocardial cells in vitro and in vivo.

The aim of the present study was to identify the correlation between expression of heat shock protein 47 (Hsp47) and stress injury in heat-stressed myocardial cells and to compare variations in Hsp47 expression in rat myocardial cells exposed to different heat stress for varying periods in vitro and in vivo. Exposure to heat stress at 42°C resulted in similar induction patterns of the heart damage-related enzyme aspartate aminotransferase in the supernatants of H9c2 cells and in the serum of rats. Histological analysis revealed that both H9c2 cells and heart tissues displayed cellular degeneration in response to different periods of heat stress. Hsp47 was constitutively expressed in the cytoplasm of H9c2 cells at all time points during heat stress, which was consistent with observations in heart fibers in vivo. Immunoblotting analysis revealed no significant difference between the expression of Hsp47 in H9c2 cells and heart tissue. However, the expression of hsp47 mRNA in response to heat stress was significantly increased in H9c2 cells at 60 min (P < 0.01) and 100 min (P < 0.01), which was comparable to that at 100 min (P < 0.01) in the rat heart. Thus, Hsp47 was elevated significantly after hyperthermia at the mRNA level but not at the protein level both in vitro and in vivo. The results suggest that Hsp47 turnover may increase during heat stress or that Hsp47 consumption exceeds its production.

Association of Hsp60 expression with damage to rat myocardial cells exposed to heat stress in vivo and in vitro.

To investigate the protective role of Hsp60 against stress damage and its role in the sudden death of stressed animals, changes in the levels of Hsp60 protein and hsp60 mRNA of myocardial cells in vivo and in vitro were studied. In addition, the relationship between Hsp60 expression and heat-induced damage was also studied. Rats were exposed to a temperature of 42° ± 1°C for 0, 20, 40, 60, 80, or 100 min. More than 50% of the rats died suddenly within 100 min. With increasing heat stress duration, hsp60 mRNA levels significantly increased in both in vivo and in vitro rat myocardial cells; however, a similar trend was not observed for Hsp60 protein levels. Although the changes observed in Hsp60 expression in myocardial cells in vitro were inconsistent with those of rat heart tissues in vivo, Hsp60 expression levels were consistent with the histopathological damage observed in myocardial cells both in vivo and in vitro. Differences in Hsp60 expression may reflect the degree of injury sustained by myocardial cells in vivo and in vitro. As a mitochondrial protein, Hsp60 represents a potential biomarker of heat stress, and may protect against heat stress induced myocardial cellular damage both in vivo and in vitro.

Expression of heat shock protein 90 alpha (Hsp90α) in primary neonatal rat myocardial cells exposed to various periods of heat stress in vitro.

The objective of this study was to investigate the mechanism of heat shock protein 90 alpha (Hsp90α) protection against heart damage resulting from heat stress by detecting Hsp90α mRNA, Hsp90α protein, protein localization, and cell damage in primary myocardial cells of neonatal rats in response to heat stress in vitro. The cells were heat-stressed at 42°C in an incubator with 95% air and 5% CO2 for different periods. Levels of Hsp90α, protein localization, enzymes, and cytopathological lesions were detected using Western blot, immunocytochemistry enzymatic assays, and cytopathological techniques. Aspartate aminotransferase, lactate dehydrogenase, and creatine kinase enzyme levels were elevated during heat stress, and acute cellular lesions that were characterized by vacuolar degeneration and necrosis were observed. Hsp90α levels decreased between 10 and 60 min of heat stress and increased after 360 and 480 min, while Hsp90α mRNA decreased after 360 min. These results indicate that heat stress might induce irreversible damage in certain myocardial cells. The elevated Hsp90α level at the end of heat stress and its positive signal in the cytoplasm of myocardial cells after heat stress could be associated with its protective role. Additionally, the consumption of Hsp90α exceeded its production in the first period of treatment.

The role of Hsp90α in heat-induced apoptosis and cell damage in primary myocardial cell cultures of neonatal rats.

To understand the mechanism underlying the sudden animal death caused by acute heart failure during heat stress, the relationships among the heat-induced pathological changes and apoptosis and the variations in the levels of protective Hsp90α and its mRNA in the heat-stressed primary myocardial cells of neonatal rats in vitro were studied by cytopathological observation, immunoblotting, RT-PCR, and analysis of the related enzymes. After a period of adaptive cell culture, the myocardial cells were immediately exposed to heat stress at 42°C for 10, 20, 40, 60, 120, 240, 360, and 480 min. Levels of creatine kinase increased from the beginning of heat stress, and the cells exposed to heat stress showed acute cellular lesions characterized by vacuolar degeneration and necrosis after 40 min of heat stress, suggesting that the myocardial cells in vitro were obviously stressed and damaged by higher temperature. The levels of cleaved caspase-3 and cytochrome C, which were related to apoptosis, increased significantly after 40 min of heat stress while the Hsp90α protein level significantly decreased. In contrast, after 6 h of exposure to heat stress, the levels of cleaved caspase-3 and cytochrome C decreased while those of Hsp90α significantly increased, suggesting that early depletion of Hsp90α coincides with a high rate of necrosis and apoptosis in heat-stressed myocardial cells, while the Hsp90α level in surviving cells increases again with significantly less apoptosis after 6 h of heat stress. These findings also indicate that apoptosis of myocardial cells occurs through the activation of the cytochrome C and caspase-3 pathway. The cell repair capacity of Hsp90α is overstrained in the early phase of heat treatment and needs some hours to stabilize. As a result, in the primary myocardial cells in vitro, Hsp90α shows protective activity against damage at the end period of the heat exposure.

Temporal variations of Hsp60 and HSF-1 in primary rat myocardial cells in vitro under heat stress.

The mechanisms involved in sudden animal death due to acute heart failure during heat stress are not well understood. We examined the relationship between heat stress-induced variations of protective Hsp60 and expression of its regulatory factor, HSF-1, in heat-stressed primary myocardial cells of neonatal rats in vitro through cardiac enzyme detection, immunoblotting, immunocytochemistry, and qPCR. Increases in cardiac damage-related enzyme levels demonstrated injury to myocardial cells after heat exposure at 42°C. Hsp60 expression levels fluctuated during heat stress; they decreased significantly after 20 min, then increased at 120 min and decreased again at 360 min after initiation of heat stress. The highest levels of Hsp60 were observed at 240 min, while the lowest were at 60 min. Damage to myocardial cells was characterized by increases in cardiac enzyme levels and low levels of Hsp60 due to functional disorder of myocardial cells at early stages of heat stress. However, the significant induction of hsp60 mRNA levels from the beginning up to 240 min of heat stress was not consistent with the classic regulatory mechanisms that link transcription and translation, suggesting that Hsp60 expression is delayed due to loss of Hsp60 during the early stages of heat stress. hsf-1 mRNA levels were significantly increased from 10 min of heat stress; however, HSF-1 protein levels did not simultaneously increase, indicating that HSF-1 is not the sole regulator of Hsp60 expression.

Hsp110 expression changes in rat primary myocardial cells exposed to heat stress in vitro.

We investigated and described the kinetics of heat shock protein (Hsp) 110 expression and distribution in rat primary myocardial cells exposed to heat stress in vitro. After incubation at 37°C for 72 h, myocardial cells were heat stressed at 42°C for 0, 10, 20, 40, 60, 120, 240, 360, and 480 min. Significant increases in aspartate transaminase, lactate dehydrogenase, and creatine kinase enzymatic activities in the myocardial cell culture media were observed during heat stress, suggesting that the integrity of the myocardial cells was altered. Immunocytochemical analysis revealed that the expressed Hsp110 was constitutively localized in the cytoplasm and in the nuclei in small amounts characterized by a granular pattern. Nuclear Hsp110 levels increased significantly after 240 min of heat stress compared with levels in the control. The overall levels of Hsp110 expression increased significantly after 20 min. After 240 min, Hsp110 levels were approximately 1.2-fold higher than those in the control. Increasing levels of hsp110 messenger RNA detected using real-time quantitative polymerase chain reaction were observed after 20 min of heat stress, and the levels peaked with a 10-fold increase after 240 min of heat stress. These results indicate that the expression of Hsp110 in primary myocardial cells in vitro is sensitive to hyperthermic stress and that Hsp110 is involved in the potential acquisition of thermotolerance after heat stress. Therefore, Hsp110 might play a fundamental role in opposing and alleviating heat-induced damage caused by hyperthermic stress in primary myocardial cells.

Effects of transportation on expression of Hsp90, Hsp70, Hsp27 and αB-crystallin in the pig stomach.

Twenty pigs were randomly divided into four groups based on the amount of time spent in transport (zero, one, two or four hours). Pathological examination of all transported pigs showed that exfoliation of chief cells from the gastric surface occurred in pigs during transportation. These results imply that integrity of the gastric mucosa was compromised by damage occurring during the four-hour transportation, despite the fact that gastric ulcers were not present. Levels of Hsp90 expression in stomach tissues were significantly decreased (P<0.01) after two-hour transportation, but Hsp70 levels increased significantly (P<0.05) after one, two and four hours of transportation. Hsp27 levels remained relatively stable independent of the length of transport. Levels of αB-crystallin expression in the stomach were significantly increased (P<0.05) after four hours of transportation. Variations in Hsp90, Hsp70, Hsp27 and αB-crystallin levels suggest that distinct protective functions are modulated by different Hsps in stomach tissues during transportation. Alterations in Hsp70 and αB-crystallin expression appear to be associated with protective functions, as no apparent gastric ulcers were present in pigs that underwent four hours of transportation. Levels of heat shock transcription factor-1, which regulate the expression of Hsps, remained relatively stable independent of the transportation period.

Naphthylthiourea-modified permethylcyclodextrin as a highly sensitive and selective "turn-on" fluorescent chemosensor for Hg2+ in water and living cells.

A naphthylthiourea-modified cyclodextrin (1) and its urea derivative (2) were synthesized, and their fluorescence behaviors in the presence of various metal ions were investigated. Significantly, 1 showed a highly sensitive and selective fluorescence sensing ability for Hg(2+) over other metal ions in both water and living cells. That is, the addition of Hg(2+) to an aqueous solution of 1 gave a significantly enhanced fluorescence at ~380 nm. In contrast, the addition of other metal ions induced negligible fluorescence changes. The possible mechanism may be due to the transformation of thiourea to urea by Hg(2+)-induced desulfurization in water.

Amphiphilic porphyrin assembly as a highly selective chemosensor for organic mercury in water.

Homogeneously sized nanoparticles were successfully constructed based on amphiphilic porphyrin-cholesterol arrays, showing unique spectral and colourimetric response to organic mercury in water, even in the presence of Hg(2+).

[Clinical study on delayed flapless implants placement after bone powder grafted immediately in postextraction sockets].

PURPOSE: To explore and evaluate the clinical outcome of delayed flapless implant placements after bone powder grafted immediately in postextraction sockets. METHODS: 23 patient requiring dental implants after postextractions were selected for this study. The fresh sockets with at least 3 walls (3 or 4 walls) were immediately grafted and filled with artificial bone powders (Bio-oss and demineralized bone powders), covered by ultra-thin titanium membranes. Bone graft got to or 2-3mm higher than the top level of the sockets. 3 months later, the alveolar bone heights were checked by routine X-ray examination. And alveolar bone ridge widths were measured by bone-width gauges. The alveolar bones were confirmed sufficient to accommodate the implant with at least 4.0mm in diameter and 9mm in length. Then flapless implant placements were performed. The primary stability of the implants was measured. The implants were followed up and success rate of implant was evaluated. RESULT: The alveolar bone height and width were basically maintained without depression and atrophy through clinical observation and X-ray examination. Flapless implant placements were performed with minor local reaction. The primary stability of 36 implants all attained to 30N. Failure did not happen during a followed up period of by 6-62 months. CONCLUSION: After bone powder grafted immediately in postextraction sockets, sufficient alveolar bone volume for implants can be preserved. Flapless implant placements in sufficient bone support can effectively simplify the preoperative examination and surgical procedures, reducing local reaction. Delayed flapless implant placements after bone powder grafted immediately in postextraction sockets is an effective design and method of dental implantation.

[Primary study on the antibacterial property of silver-loaded nano-titania coatings].

OBJECTIVE: To study the preparation and characteristics of silver-loaded nano-titania coating so as to develop a bioactive implant material with antibacterial property. METHODS: Plasma sprayed nano-titania coatings were immersed in 1%, 5%, and 9% AgNO3 solution to load silver. The loaded silver and its distribution were evaluated by scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS). After optimizing the preparation process, the release rate of silver from the nano-titania coating was measured in deionized water, its corresponding in vitro cytotoxicity and antibacterial activity were also examined. RESULTS: The loaded silver was in proper quantity and distributed evenly on the nano-titania coatings after immersion in 5% AgNO3. A burst release of the silver could be detected. The quick release of silver from the titania coatings sustained about 12 days in deionized water, which had no obvious influence on the surface morphology of titania coatings. The loaded silver did not inhibit the osteoblast proliferation (P = 0.1) and alkaline phosphatase expression (P = 0.06), however, it effectively inhibited the survival and growth of Staphylococcus aureus for 12 days: the zone of inhibition reached 3.81 +/- 0.8 mm with a bacteria killing rate of 100%. CONCLUSIONS: It is economical and effective to prepare the silver-loaded nano-titania coatings by 5% AgNO3 solution. The loaded silver has good antibacterial function, and shows no obvious effect on the physical and biological properties of nano-titania coatings.