Fluoride varnishes with calcium glycerophosphate: fluoride release and effect on in vitro enamel demineralization

The aims of this study were (1) to assess the amount of fluoride (F) released from varnishes containing calcium glycerophosphate (CaGP) and (2) to assess the effect of the experimental varnishes on in vitro demineralization. Six test groups using 5 varnishes: base varnish (no active ingredients); Duraphat® (2.26% NaF); Duofluorid® (5.63% NaF/CaF2); experimental varnish 1 (1% CaGP/5.63% NaF/CaF2); experimental varnish 2 (5% CaGP/5.63% NaF/CaF2); and no varnish were set up. In stage 1, 60 acrylic blocks were randomly distributed into 6 groups (n = 10). Then 300 µg of each varnish was applied to each block. The blocks were immersed in deionized water, which was changed after 1, 8, 12, 24, 48 and 72 hours. Fluoride concentration in the water was analyzed using a fluoride electrode. In stage 2, 60 bovine enamel samples were distributed into 6 groups (n = 10), and treated with 300 µg of the respective varnish. After 6 h the varnish was removed and the samples were subjected to a 7-day in vitro pH cycle (6 h demineralization/18 h remineralization per day). The demineralization was measured using surface hardness. The results showed that both experimental varnishes released more fluoride than Duofluorid® and Duraphat® (p < 0.05), but Duraphat® showed the best preventive effect by decreasing enamel hardness loss (p < 0.05). Therefore, we conclude that even though (1) the experimental varnishes containing CaGP released greater amounts of F, (2) they did not increase in the preventive effect against enamel demineralization.

Exploring Growth Variability and Crown Vitality of Sessile Oak (Quercus Petraea) in the Czech Republic

Unraveling climatic effects on growth of oak - Europe’s most ecologically and economically important forest species - has been the subject of many recent studies; however, more insight based on field data is necessary to better understand the relationship between climate and tree growth and to adapt forest management strategies to future climate change. In this report, we explore the influence of temperature, precipitation and drought variability on the productivity and vitality of oak stands in the Czech Highlands. We collected 180 cores from mature oaks (Quercus petraea) at four forest stands in the Czech Drahany Highlands. Standard dendromethods were used for sample preparation, ring width measurements, cross-dating, chronology development, and the assessment of growth-climate response patterns. Crown vitality was also evaluated, using the modified ICP Forests methodology. Late spring precipitation totals between May and June as well as the mean July temperature for the year of ring formation were found to be the most important factors for oak growth, whereas crown condition was significantly affected by spring and summer drought. This study is rep-resentative for similar bio-ecological habitats across Central Europe and can serve as a dendroclima-tological blueprint for earlier periods for which detailed meteorological information is missing .

Endoscopic and Open Release Similarly Safe for the Treatment of Carpal Tunnel Syndrome. A Systematic Review and Meta-Analysis.

BACKGROUND The Endoscopic Release of Carpal Tunnel Syndrome (ECTR) is a minimal invasive approach for the treatment of Carpal Tunnel Syndrome. There is scepticism regarding the safety of this technique, based on the assumption that this is a rather "blind" procedure and on the high number of severe complications that have been reported in the literature. PURPOSE To evaluate whether there is evidence supporting a higher risk after ECTR in comparison to the conventional open release. METHODS We searched MEDLINE (January 1966 to November 2013), EMBASE (January 1980 to November 2013), the Cochrane Neuromuscular Disease Group Specialized Register (November 2013) and CENTRAL (2013, issue 11 in The Cochrane Library). We hand-searched reference lists of included studies. We included all randomized or quasi-randomized controlled trials (e.g. study using alternation, date of birth, or case record number) that compare any ECTR with any OCTR technique. Safety was assessed by the incidence of major, minor and total number of complications, recurrences, and re-operations.The total time needed before return to work or to return to daily activities was also assessed. We synthesized data using a random-effects meta-analysis in STATA. We conducted a sensitivity analysis for rare events using binomial likelihood. We judged the conclusiveness of meta-analysis calculating the conditional power of meta-analysis. CONCLUSIONS ECTR is associated with less time off work or with daily activities. The assessment of major complications, reoperations and recurrence of symptoms does not favor either of the interventions. There is an uncertain advantage of ECTR with respect to total minor complications (more transient paresthesia but fewer skin-related complications). Future studies are unlikely to alter these findings because of the rarity of the outcome. The effect of a learning curve might be responsible for reduced recurrences and reoperations with ECTR in studies that are more recent, although formal statistical analysis failed to provide evidence for such an association. LEVEL OF EVIDENCE I.

Platelet-rich concentrates differentially release growth factors and induce cell migration in vitro

BACKGROUND Platelet-rich concentrates are used as a source of growth factors to improve the healing process. The diverse preparation protocols and the gaps in knowledge of their biological properties complicate the interpretation of clinical results. QUESTIONS/PURPOSES In this study we aimed to (1) analyze the concentration and kinetics of growth factors released from leukocyte- and platelet-rich fibrin (L-PRF), leukocyte- and platelet-rich plasma (L-PRP), and natural blood clot during in vitro culture; (2) investigate the migration of mesenchymal stem cells (MSCs) and human umbilical vein endothelial cells (HUVECs) as a functional response to the factors released; and (3) uncover correlations between individual growth factors with the initial platelet/leukocyte counts or the induced cell migration. METHODS L-PRF, L-PRP, and natural blood clot prepared from 11 donors were cultured in vitro for 28 days and media supernatants collected after 8 hours and 1, 3, 7, 14, and 28 days. Released transforming growth factor β1 (TGF-β1), vascular endothelial growth factor (VEGF), insulin growth factor (IGF-1), platelet-derived growth factor AB (PDGF-AB), and interleukin-1β (IL-1β) were measured in the supernatants with enzyme-linked immunosorbent assay. Migration of MSC and HUVEC induced by the supernatants was evaluated in Boyden chambers. RESULTS More TGF-ß1 was released (mean ± SD in pg/mL of blood) from L-PRF (37,796 ± 5492) compared with L-PRP (23,738 ± 6848; p < 0.001) and blood clot (3739 ± 4690; p < 0.001), whereas more VEGF and IL-1ß were released from blood clot (1933 ± 704 and 2053 ± 908, respectively) compared with both L-PRP (642 ± 208; p < 0.001 and 273 ± 386; p < 0.001, respectively) and L-PRF (852 ± 376; p < 0.001 and 65 ± 56, p < 0.001, respectively). No differences were observed in IGF-1 and PDGF-AB released from any of the concentrates. TGF-β1 release peaked at Day 7 in L-PRF and at 8 hours and Day 7 in L-PRP and 8 hours and Day 14 in blood clot. In all concentrates, main release of VEGF occurred between 3 and 7 days and of IL-1β between Days 1 and 7. IGF-1 and PDGF-AB were released until Day 1 in L-PRP and blood clot, in contrast to sustained release over the first 3 days in L-PRF. The strongest migration of MSC occurred in response to L-PRF, and more HUVEC migration was seen in L-PRF and blood clot compared with L-PRP. TGF-β1 correlated with initial platelet counts in L-PRF (Pearson r = 0.66, p = 0.0273) and initial leukocyte counts in L-PRP (Pearson r = 0.83, p = 0.0016). A positive correlation of IL-1β on migration of MSC and HUVEC was revealed (Pearson r = 0.16, p = 0.0208; Pearson r = 0.31, p < 0.001). CONCLUSIONS In comparison to L-PRP, L-PRF had higher amounts of released TGF-β1, a long-term release of growth factors, and stronger induction of cell migration. Future preclinical studies should confirm these data in a defined injury model. CLINICAL RELEVANCE By characterizing the biologic properties of different platelet concentrates in vitro, we may gain a better understanding of their clinical effects and develop guidelines for specific future applications.

Effects of Antiseptic Solutions Commonly Used in Dentistry on Bone Viability, Bone Morphology, and Release of Growth Factors

PURPOSE Antiseptic solutions are commonly used in dentistry for a number of sterilization procedures, including harvesting of bone chips, irrigation of extraction sockets, and sterilization of osteonecrotic bone. Despite its widespread use, little information is available regarding the effects of various antiseptic solutions on bone cell viability, morphology, and the release of growth factors. MATERIALS AND METHODS The antiseptic solutions included 1) 0.5% povidone iodine (PI), 2) 0.2% chlorhexidine diguluconate (CHX), 3) 1% hydrogen peroxide (H2O2), and 4) 0.25% sodium hypochlorite (HYP). Bone samples collected from porcine mandibular cortical bone were rinsed in the antiseptic solutions for 10 minutes and assessed for cell viability using an MTS assay and protein release of transforming growth factor (TGF-β1), bone morphogenetic protein 2 (BMP2), vascular endothelial growth factor (VEGF), interleukin (IL)-1β, and receptor activator of nuclear factor κB ligand (RANKL) using an enzyme-linked immunosorbent assay at 15 minutes and 4 hours after rinsing. RESULTS After antiseptic rinsing, changes to the surface protein content showed marked alterations, with an abundant protein layer remaining on CHX-rinsed bone samples. The amount of surface protein content gradually decreased in the following order: CHX, H2O2, PI, and HYP. A similar trend was also observed for the relative cell viability from within bone samples after rinsing, with up to 6 times more viable cells found in the CHX-rinsed bone samples than in the HYP- and PI-rinsed samples. An analysis of the growth factors found that both HYP and PI had significantly lower VEGF and TGF-β1 protein release from bone samples at 15 minutes and 4 hours after rinsing compared with CHX and H2O2. A similar trend was observed for RANKL and IL-1β protein release, although no change was observed for BMP2. CONCLUSIONS The results from the present study have demonstrated that antiseptic solutions present with very different effects on bone samples after 10 minutes of rinsing. Rinsing with CHX maintained significantly higher cell viability and protein release of growth factors potent to the bone remodeling cycle.

Comparative release of growth factors from PRP, PRF, and advanced-PRF

OBJECTIVES The use of platelet concentrates has gained increasing awareness in recent years for regenerative procedures in modern dentistry. The aim of the present study was to compare growth factor release over time from platelet-rich plasma (PRP), platelet-rich fibrin (PRF), and a modernized protocol for PRF, advanced-PRF (A-PRF). MATERIALS AND METHODS Eighteen blood samples were collected from six donors (3 samples each for PRP, PRF, and A-PRF). Following preparation, samples were incubated in a plate shaker and assessed for growth factor release at 15 min, 60 min, 8 h, 1 day, 3 days, and 10 days. Thereafter, growth factor release of PDGF-AA, PDGF-AB, PDGF-BB, TGFB1, VEGF, EGF, and IGF was quantified using ELISA. RESULTS The highest reported growth factor released from platelet concentrates was PDGF-AA followed by PDGF-BB, TGFB1, VEGF, and PDGF-AB. In general, following 15-60 min incubation, PRP released significantly higher growth factors when compared to PRF and A-PRF. At later time points up to 10 days, it was routinely found that A-PRF released the highest total growth factors. Furthermore, A-PRF released significantly higher total protein accumulated over a 10-day period when compared to PRP or PRF. CONCLUSION The results from the present study indicate that the various platelet concentrates have quite different release kinetics. The advantage of PRP is the release of significantly higher proteins at earlier time points whereas PRF displayed a continual and steady release of growth factors over a 10-day period. Furthermore, in general, it was observed that the new formulation of PRF (A-PRF) released significantly higher total quantities of growth factors when compared to traditional PRF. CLINICAL RELEVANCE Based on these findings, PRP can be recommended for fast delivery of growth factors whereas A-PRF is better-suited for long-term release.

Influence of root canal disinfectants on growth factor release from dentin

INTRODUCTION During dentinogenesis, growth factors become entrapped in the dentin matrix that can later be released by demineralization. Their effect on pulpal stem cell migration, proliferation, and differentiation could be beneficial for regenerative endodontic therapies. However, precondition for success, as for conventional root canal treatment, will be sufficient disinfection of the root canal system. Various irrigation solutions and intracanal dressings are available for clinical use. The aim of this study was 2-fold: to identify a demineralizing solution suitable for growth factor release directly from dentin and to evaluate whether commonly used disinfectants for endodontic treatment will compromise this effect. METHODS Dentin disks were prepared from extracted human teeth and treated with EDTA or citric acid at different concentrations or pH for different exposure periods. The amount of transforming growth factor-β1 (TGF-β1), fibroblast growth factor 2, and vascular endothelial growth factor were quantified via enzyme-linked immunosorbent assay and visualized by gold labeling. Subsequently, different irrigation solutions (5.25% sodium hypochloride, 0.12% chlorhexidine digluconate) and intracanal dressings (corticoid-antibiotic paste, calcium hydroxide: water-based and oil-based, triple antibiotic paste, chlorhexidine gel) were tested, and the release of TGF-β1 was measured after a subsequent conditioning step with EDTA. RESULTS Conditioning with 10% EDTA at pH 7 rendered the highest amounts of TGF-β1 among all test solutions. Fibroblast growth factor 2 and vascular endothelial growth factor were detected after EDTA conditioning at minute concentrations. Irrigation with chlorhexidine before EDTA conditioning increased TGF-β1 release; sodium hypochloride had the opposite effect. All tested intracanal dressings interfered with TGF-β1 release except water-based calcium hydroxide. CONCLUSIONS Growth factors can be released directly from dentin via EDTA conditioning. The use of disinfecting solutions or medicaments can amplify or attenuate this effect.

Changes of Root Length and Root-to-Crown Ratio after Apical Surgery: An Analysis by Using Cone-beam Computed Tomography

INTRODUCTION Apical surgery is an important treatment option for teeth with post-treatment periodontitis. Although apical surgery involves root-end resection, no morphometric data are yet available about root-end resection and its impact on the root-to-crown ratio (RCR). The present study assessed the length of apicectomy and calculated the loss of root length and changes of RCR after apical surgery. METHODS In a prospective clinical study, cone-beam computed tomography scans were taken preoperatively and postoperatively. From these images, the crown and root lengths of 61 roots (54 teeth in 47 patients) were measured before and after apical surgery. Data were collected relative to the cementoenamel junction (CEJ) as well as to the crestal bone level (CBL). One observer took all measurements twice (to calculate the intraobserver variability), and the means were used for further analysis. The following parameters were assessed for all treated teeth as well as for specific tooth groups: length of root-end resection and percentage change of root length, preoperative and postoperative RCRs, and percentage change of RCR after apical surgery. RESULTS The mean length of root-end resection was 3.58 ± 1.43 mm (relative to the CBL). This amounted to a loss of 33.2% of clinical and 26% of anatomic root length. There was an overall significant difference between the tooth groups (P < .05). There was also a statistically significant difference comparing mandibular and maxillary teeth (P < .05), but not for incisors/canines versus premolars/molars (P = .125). The mean preoperative and postoperative RCRs (relative to CEJ) were 1.83 and 1.35, respectively (P < .001). With regard to the CBL reference, the mean preoperative and postoperative RCRs were 1.08 and 0.71 (CBL), respectively (P < .001). The calculated changes of RCR after apical surgery were 24.8% relative to CEJ and 33.3% relative to CBL (P < .001). Across the different tooth groups, the mean RCR was not significantly different (P = .244 for CEJ and 0.114 for CBL). CONCLUSIONS This CBCT-based study demonstrated that the RCR is significantly changed after root-end resection in apical surgery irrespective of the clinical (CBL) or anatomic (CEJ) reference levels. The lowest, and thus clinically most critical, postoperative RCR was observed in maxillary incisors. Future clinical studies need to show the impact of resection length and RCR changes on the outcome of apical surgery.

DIRECT EFFECT OF MELATONIN UPON THE RELEASE OF GONADOTROPINS FROM THE SUPERFUSED PITUITARY GLAND OF THE MALE GOLDEN HAMSTER

The pineal gland is known to be light sensitive and to be involved in the seasonal reproduction of male golden hamster Mesocricetus auratus. In general, the pineal gland has been demonstrated to be inhibitory to the reproductive system of the male golden hamster. Melatonin is a pineal hormone which can mimic the action of the pineal gland upon the reproductive system. However, the actual site(s) of melatonin action in the hamster has not been demonstrated. In this study a direct effect of melatonin on the release of FSH and LH from superfused hamster pituitary glands was investigated.^ The superfused pituitary glands showed a stable in vitro basal release of FSH and LH for up to 10 hours. The superfused pituitaries demonstrated reproducible responses to repeated pulses of 10('-8) M LHRH, and a dose-dependent response to stimulation with different concentrations of LHRH.^ Melatonin inhibited the basal release of FSH and LH from superfused hamster pituitary glands. This effect of melatonin was specific and not a general indolamine or catecholamine effect.^ The superfused pituitaries had a diurnal differential responsiveness to physiological concentrations of melatonin with respect to FSH and LH release which were related to the light cycle used to maintain the experimental animals. A LD 14:10 photoperiod cycle was used with light on from 5 a.m. till 7 p.m.. With pituitary glands obtained at 8:30 a.m., the basal release of FSH exhibited an initial inhibition, a gradual rebound at approximately two hours after the beginning of melatonin superfusion, and a significant overshoot of FSH release after the cessation of infusion with melatonin (Morning Response). If the pituitary glands were obtained from hamsters which were sacrificed at 3:30 p.m., the release rate of FSH exhibited an inhibition during the entire period of melatonin infusion with a rebound effect appearing only after melatonin infusion was discontinued (Afternoon Response). There was no significant difference in the responsiveness of the pituitary gland to infusion with melatonin at either 8:30 a.m. or 3:30 p.m. with respect to LH release. Also, melatonin could not inhibit the gonadotropins response to continuous superfusion with 10('-9) M LHRH in pituitaries obtained at either 8:30 a.m. or 3:30 p.m., nor inhibit the stimulatory effect of pulsatile 10('-9) M LHRH. . . . (Author's abstract exceeds stipulated maximum length. Discontinued here with permission of author.) UMI^

THE INHIBITORY EFFECTS OF VSV INFECTION ON MULV PRODUCTION OCCUR BETWEEN SYNTHESIS AND RELEASE OF MULV GENOMIC RNA

The inhibitory effects of VSV infection on MuLV production were investigated using the VSV temperature-sensitive mutants t1B17(I & V), tsT1026(I), tsG22(II), and ts052(II). At the permissive temperature, all four mutants suppressed the release of virion-associated MuLV gRNA by approximately 98% within 0.5 to 2.5 hr post infection. At the restrictive temperature and in the absence of cell killing, infection with t1B17(I & V) inhibited the release of MuLV gRNA, while tsT1026(I) and tsG22(II) did not. In contrast, ts052(II) inhibited the release of MuLV gRNA and induced cell killing. During the same time period and at either temperature, all four mutants did not suppress either MuLV-associated protein release or intracellular MuLV sRNA synthesis. These results indicate that VSV inhibits MULV gRNA release at a level somewhere between the synthesis and release of newly synthesized gRNA.^

THE ROLE OF B CELLS IN THE T CELL DEPENDENT RELEASE OF HUMAN B CELL GROWTH FACTOR

Quiescent human B cells are postulated to go through activation and proliferation phases before undergoing differentiative phase for immunoglobulin secretion. The present studies address some of the aspects of activation and proliferation phase of normal human B cells. The definitions of signals responsible for B cell activation and proliferation resulted in the development of a highly specific, reproducible B cell growth factor (BCGF) assay. This BCGF bioassay utilizes activation by rabbit anti-human IgM-antibody. The functional specificity of this assay for measuring BCGF activity was demonstrated by the finding that target B cells proliferated but did not differentiate. The factor specificity was determined by specific absorption of BCGF by anti-IgM activated B cells. This assay was utilized for the studies of T-B cell collaboration and the essential function of monocytes in the production and/or release of B cell growth factor in a syngeneic in vitro system. It is apparent that highly purified T cells are poor producers of BCGF by themselves and require monocytes to secrete significant quantities of BCGF upon PHA stimulation. Macrophage soluble factor, Interleukin 1, is capable of replacing monocyte function for the release of BCGF by activated T cells. In our studies, B cells are incapable to function as accessory cells to replace monocyte function. Normal B cells are also not capable of producing BCGF under our experimental observations. However, the addition of these B cells at an optimum cell density (T:B ratio 1:1) doubles the monocyte dependent release of BCGF by syngeneic T cells. The augmentative role of B cells is expanded to understand the mechanism of BCGF release by T cells. It is observed from our studies that DR antigen of B cell surface is involved in the release of BCGF. The functional difference between DR of B cells and monocytes is observed as IL-1 could replace DR-treated monocytes whereas failed to replace DR-treated B cells for the release of BCGF by T cells. This functional difference may be attributed to the reported microheterogeneity in DR of B cells and monocytes. The addition of irradiated B cells increased the monocyte dependent T cell proliferation, suggesting the increase of T cell pool for BCGF release. In summary, the development of a biological assay specific for B cell growth factor led to the delineation of an interesting role of B cells in the release of its own growth factor by T cells. . . . (Author's abstract exceeds stipulated maximum length. Discontinued here with permission of author.) UMI ^

Bentgrass response to K fertilization and K release rates from eight sand rootzone sources used in putting green construction.

There is a lack of plant response to fertilizer K in some sandy soils even though routine soil tests for soil available K are shown to be low. This lack of plant response to K fertilizer application may be explained by K release from nonexchangeable forms. Greenhouse and laboratory experiments were conducted to evaluate (a) response of bentgrass (Agrostis palustris [Agrostis stolonifera var. palustris]) cv. Pencross grown in rootzones with different sand sources to K fertilizer application and (b) K release from nonexchangeable forms from the different sand sources as an index to K availability. Experimental variables in the greenhouse were 2 K levels (0 and 250 mg K/kg soil) and 8 sand rootzone sources. Rootzone soils were sub-irrigated to ensure no K loss from leaching. Two laboratory methods (boiling 1 M HNO3 extraction and continuous leaching with 0.01 M HCl) and total K uptake by the bentgrass were employed to index K release from nonexchangeable forms for each rootzone source. K fertilizer application significantly increased bentgrass yield growing in one rootzone source and root weight in 3 rootzone sources. K uptake by bentgrass and the 2 laboratory methods showed important differences in K release from the sand rootzones. The K removed by the 2 laboratory methods was closely related to leaf tissue K and K uptake, with the 1 M HNO3 extraction method providing the closest fit. The release of K from primary minerals in some rootzones with high sand content is proceeding at rates to satisfy bentgrass requirements for K. The 1 M HNO3 extraction method may provide an alternative to the routine laboratory procedures presently being used to measure the extractable K in sand-based constructed putting greens by measuring K contributed by nonexchangeable forms.