Reproductive investment and seedling survival of the mast-fruiting rain forest tree, Microberlinia bisulcata A. chev

In the southern part of Korup National Park, Cameroon, the mast fruiting tree Microberlinia bisulcata occurs as a codominant in groves of ectomycorrhizal Caesalpiniaceae within a mosaic of otherwise species-rich lowland rain forest. To estimate the amount of carbon and nutrients invested in reproduction during a mast fruiting event, and the consequential seed and seedling survival, three related field studies were made in 1995. These provided a complete seed and seedling budget for the cohort. Seed production was estimated by counting woody pods on the forest floor. Trees produced on average 26,000 (range 0-92,000) seeds/tree, with a dry mass of 16.6 kg/tree. Seeds were contained in woody pods of mass 307 kg/tree. Dry mass production of pods and seeds was 1034 kg ha(-1), equivalent to over half (55%) of annual leaf litterfall for this species, and contained 13% of the nitrogen and 21% of the phosphorus in annual leaf litterfall. Seed and young-seedling mortality was investigated with open quadrats and cages to exclude vertebrate predators, at two distances from the parent tree. The proportion of seeds on the forest floor which disappeared in the first 6 wk after dispersal was 84%, of which 26.5% was due to likely vertebrate removal, 36% to rotting, and 21.5% to other causes. Vertebrate predation was greater close to the stem than 5 m beyond the crown (41 vs 12% of seeds disappearing) where the seed shadow was less dense. Previous studies have demonstrated an association between mast years at Korup and high dry-season radiation before flowering, and have shown lower leaf-litterfall phosphorus concentrations following mast fruiting. The emerging hypothesis is that mast fruiting is primarily imposed by energy limitation for fruit production, but phosphorus supply and vertebrate predation are regulating factors. Recording the survival of naturally-regenerating M. bisulcata seedlings (6-wk stage) showed that 21% of seedlings survived to 31 mo. A simple three-stage recruitment model was constructed. Mortality rates were initially high and peaked again in each of the next two dry seasons, with smaller peaks in the two intervening wet seasons, these latter coinciding with annual troughs in radiation. The very poor recruitment of M. bisulcata trees in Korup, demonstrated in previous investigations, appears not to be due to a limitation in seed or young-seedling supply, but rather by factors operating at the established-seedling stage.

Apparent survival of the salamander

Background Understanding the demographic processes underlying population dynamics is a central theme in ecology. Populations decline if losses from the population (i.e., mortality and emigration) exceed gains (i.e., recruitment and immigration). Amphibians are thought to exhibit little movement even though local populations often fluctuate dramatically and are likely to go exinct if there is no rescue effect through immigration from nearby populations. Terrestrial salamanders are generally portrayed as amphibians with low migratory activity. Our study uses demographic analysis as a key to unravel whether emigration or mortality is the main cause of "losses" from the population. In particular, we use the analysis to challenge the common belief that terrestrial salamanders show low migratory activity. Results The mark-recapture analysis of adult salamanders showed that monthly survival was high (> 90%) without a seasonal pattern. These estimates, however, translate into rather low rates of local annual survival of only ~40% and suggest that emigration was important. The estimated probability of emigration was 49%. Conclusion Our analysis shows that terrestrial salamanders exhibit more migratory activity than commonly thought. This may be due either because the spatial extent of salamander populations is underestimated or because there is a substantial exchange of individuals between populations. Our current results are in line with several other studies that suggest high migratory activity in amphibians. In particular, many amphibian populations may be characterized by high proportions of transients and/or floaters.

Extended duration of torsional loading reduced the survival of the NP cells of the intervertebral disc

Introduction Previous studies on the influence of torsion and combined torsion-compression loading revealed a positive effect on the cell viability when a repetitive short-term torsion was applied at a physiological magnitude to intervertebral disc organ culture.1 However, after an extended period (8 hours) of combined torsion-compression loading, substantial cell death was detected in the nucleus pulposus (NP).2 In this follow-up study, we aimed to investigate the relationship, if any, between the duration of torsion applied to the intervertebral disc (IVD) and the level of NP cell viability. Materials and Methods Bovine caudal discs were harvested and cultured in a custom-built multiaxis dynamic loading bioreactor.2 Torsion (± 2 degrees) was applied to the samples at a frequency of 0.2 Hz. Torsion was applied for durations of 0, 1, 4, and 8 h/d, repeated over 7 days. After the last day of loading, disc tissue was dissected for analysis of cell viability and gene expression. Results Disc NP cell viability remained above 85% after torsional loading for 0, 1, or 4 h/d. Viability was statistical significantly reduced to below 70% when torsion was applied for 8 h/d (p = 0.03) (Table 1). The daily duration of torsional loading did not affect the AF cell viability (> 80% for all loading durations). The trend of collagen 2 gene upregulation and matrix metalloproteases 13 downregulation with an increasing duration of torsion was observed in both NP and AF (Fig. 1).Conclusion We have demonstrated that an extended duration of torsion could inhibit the survival of NP cells within the IVD in organ culture. Acknowledgments Funds from the Orthopedic Department of the Insel University Hospital of Bern and a private donation from Prof. Dr. Paul Heini, Spine Surgeon, Sonnenhof Clinic Bern were received to support this work. Disclosure of Interest None declared References References 1 Chan SC, Ferguson SJ, Wuertz K, Gantenbein-Ritter B. Biological response of the intervertebral disc to repetitive short-term cyclic torsion. Spine 2011;36(24):2021–2030 2 Chan SC, Walser J, Käppeli P, Shamsollahi MJ, Ferguson SJ, Gantenbein-Ritter B. Region specific response of intervertebral disc cells to complex dynamic loading: an organ culture study using a dynamic torsion-compression bioreactor. PLoS ONE 2013;8(8):e72489

The function of secretory IgA in the context of the intestinal continuum of adaptive immune responses in host-microbial mutualism

The large production of immunoglobulin (Ig)A is energetically costly. The fact that evolution retained this apparent luxury of intestinal class switch recombination to IgA within the human population strongly indicates that there must be a critical specific function of IgA for survival of the species. The function of IgA has been investigated in a series of different models that will be discussed here. While IgA has clear protective functions against toxins or in the context of intestinal viral infections, the function of IgA specific for non-pathogenic commensal bacteria remains unclear. In the context of the current literature we present a hypothesis where secretory IgA integrates as an additional layer of immune function into the continuum of intestinal CD4 T cell responses, to achieve a mutualistic relationship between the intestinal commensal microbiota and the host.

Expression and hypoxic regulation of the endothelin system in endocrine cells of human and rat pancreatic islets

CONTEXT: The success of pancreatic islet transplantation depends largely on the capacity of the islet graft to survive the initial phase immediately after transplantation until revascularization is completed. Endothelin-1 (ET-1) is a strong vasoconstrictor which has been involved in solid organ graft failure but is also known to be a potent mitogenic/anti-apoptotic factor which could also potentially enhance the survival of the transplanted islets. OBJECTIVE: Characterization of the endothelin system with regard to a potential endothelin agonist/antagonist treatment. DESIGN: Regulated expression of the endothelin system in human and rat pancreatic islets and beta-cell lines was assessed by means of immunohistochemistry, competition binding studies, western blot, RT-PCR, real-time PCR and transplant studies. RESULTS: ET-1, ETA- and ETB-receptor immunoreactivity was identified in the endocrine cells of human and rat pancreatic islets. The corresponding mRNA was detectable in rat beta-cell lines and isolated rat and human pancreatic islets. Competition binding studies on rat islets revealed binding sites for both receptor types. ET-1 stimulated the phosphorylation of mitogen-activated protein kinase, which was prevented by ETA- and ETB-receptor antagonists. After exposure to hypoxia equal to post-transplant environment oxygen tension, mRNA levels of ET-1 and ETB-receptor of human islets were robustly induced whereas ETA-receptor mRNA did not show significant changes. Immunostaining signals for ET-1 and ETA-receptor of transplanted rat islets were markedly decreased when compared to native pancreatic sections. CONCLUSIONS: In pancreatic islets, ET-1 and its receptors are differentially expressed by hypoxia and after transplantation. Our results provide the biological basis for the study of the potential use of endothelin agonists/antagonists to improve islet transplantation outcome.

Survival of palatal miniscrews used for orthodontic appliance anchorage: a retrospective cohort study

INTRODUCTION The purpose of this study was to examine the overall success of miniscrews inserted in the paramedian palatal region for support of various appliances during orthodontic treatment. METHODS The patients received 1 or 2 miniscrews in the paramedian anterior palate of 8.0-mm length and 1.6-mm diameter placed during orthodontic treatment by the same experienced orthodontist. RESULTS In total, 196 patients (121 girls, 75 boys; median age, 11.7; interquartile range, 3.7) who received 384 miniscrews were evaluated. Two hundred four miniscrews were used with rapid palatal expansion appliances, 136 with appliances for distalization of posterior teeth, and 44 with other appliances, such as transpalatal arches for tooth stabilization. The overall survival of the miniscrews was excellent (97.9%) in the cases examined. Cox regression analysis showed no difference in the overall survival rates of miniscrews loaded with different appliances for sex (hazard ratio, 0.95; 95% confidence interval, 0.71-1.27; P = 0.73) after adjusting for appliance and age. CONCLUSIONS This study shows that miniscrews placed in the paramedian anterior palate for supporting various orthodontic appliances have excellent survival.

Characterization of the 9L gliosarcoma implanted in the Fischer rat: an orthotopic model for a grade IV brain tumor.

Among rodent models for brain tumors, the 9L gliosarcoma is one of the most widely used. Our 9L-European Synchrotron Radiation Facility (ESRF) model was developed from cells acquired at the Brookhaven National Laboratory (NY, USA) in 1997 and implanted in the right caudate nucleus of syngeneic Fisher rats. It has been largely used by the user community of the ESRF during the last decade, for imaging, radiotherapy, and chemotherapy, including innovative treatments based on particular irradiation techniques and/or use of new drugs. This work presents a detailed study of its characteristics, assessed by magnetic resonance imaging (MRI), histology, immunohistochemistry, and cytogenetic analysis. The data used for this work were from rats sampled in six experiments carried out over a 3-year period in our lab (total number of rats = 142). The 9L-ESRF tumors were induced by a stereotactic inoculation of 10(4) 9L cells in the right caudate nucleus of the brain. The assessment of vascular parameters was performed by MRI (blood volume fraction and vascular size index) and by immunostaining of vessels (rat endothelial cell antigen-1 and type IV collagen). Immunohistochemistry and regular histology were used to describe features such as tumor cell infiltration, necrosis area, nuclear pleomorphism, cellularity, mitotic characteristics, leukocytic infiltration, proliferation, and inflammation. Moreover, for each of the six experiments, the survival of the animals was assessed and related to the tumor growth observed by MRI or histology. Additionally, the cytogenetic status of the 9L cells used at ESRF lab was investigated by comparative genomics hybridization analysis. Finally, the response of the 9L-ESRF tumor to radiotherapy was estimated by plotting the survival curves after irradiation. The median survival time of 9L-ESRF tumor-bearing rats was highly reproducible (19-20 days). The 9L-ESRF tumors presented a quasi-exponential growth, were highly vascularized with a high cellular density and a high proliferative index, accompanied by signs of inflammatory responses. We also report an infiltrative pattern which is poorly observed on conventional 9 L tumor. The 9L-ESRF cells presented some cytogenetic specificities such as altered regions including CDK4, CDKN2A, CDKN2B, and MDM2 genes. Finally, the lifespan of 9L-ESRF tumor-bearing rats was enhanced up to 28, 35, and 45 days for single doses of 10, 20, and 2 × 20 Gy, respectively. First, this report describes an animal model that is used worldwide. Second, we describe few features typical of our model if compared to other 9L models worldwide. Altogether, the 9L-ESRF tumor model presents characteristics close to the human high-grade gliomas such as high proliferative capability, high vascularization and a high infiltrative pattern. Its response to radiotherapy demonstrates its potential as a tool for innovative radiotherapy protocols.

Failure Rate and Conductor Externalization of the Biotronik Linox / Sorin Vigila Implantable Cardioverter Defibrillator Lead

BACKGROUND We observed a case of conductor externalization in a Biotronik Linox lead. OBJECTIVE To investigate lead performance of the Linox and identical Sorin Vigila lead and prevalence of conductor externalization. METHODS We compared lead performance of all Linox and Vigila leads implanted at our center (BL group; n=93) with all Boston Scientific Endotak Reliance leads (ER group; n=190) and Medtronic Sprint Quattro leads (SQ group; n=202) implanted during the same period. We screened all BL group patients for conductor externalization. RESULTS We identified 8 cases of lead failures in the BL group (index case of conductor externalization; 6 cases of non-physiological high rate sensing; one case of high voltage conductor fracture). Prospective, fluoroscopic screening of 98% of all active BL group cases revealed one additional case of conductor externalization. Median follow-up was 41, 27 and 29 months for the BL group, ER group and SQ group, respectively, lead survival 94.9%, 99.2% and 100% at 3 years, and 88%, 97.5% and 100% at 5 years (p=0.038 for BL group vs. ER group, and p=0.007 for BL group vs. SQ group by the log-rank test). Younger age at implant was an independent predictor for lead failure in the BL group (adjusted HR 0.85 [95% confidence interval 0.77-0.94]; p=0.001). CONCLUSION At our center, survival of the Linox lead is 88% at five years and significantly worse than its comparators. Conductor externalization is present in a minority of failed Linox leads. Younger age at implant is an independent predictor of Linox lead failure.

Reversal of established lupus nephritis and prolonged survival of New Zealand black x New Zealand white mice treated with the topoisomerase I inhibitor irinotecan

Systemic lupus erythematosus is a chronic autoimmune disorder that predominantly affects women of childbearing age. Lupus-associated glomerulonephritis is a major cause of mortality in these patients. Current treatment protocols for systemic lupus erythematosus include cyclophosphamide, prednisolone, azathioprine, and mycophenolate mofetil. However, in mice none of these agents alone or in combination were shown to reverse established proteinuria. Using New Zealand Black x New Zealand White F1 mice, we report that administration of the topoisomerase I inhibitor irinotecan from week 13 completely prevented the onset of proteinuria and prolonged survival up to at least 90 wk without detectable side effects. Furthermore, application of irinotecan to mice with established lupus nephritis, as indicated by grade 3+ (> or =300 mg/dl) and grade 4+ (> or =2000 mg/dl) proteinuria and, according to a median age of 35 wk, resulted in remission rates of 75% and 55%, respectively. Survival was significantly prolonged with 73 wk (grade 3+ and 4+ combined) versus 40 wk for control animals. Although total IgG and anti-dsDNA Abs in the serum and mesangial IgG deposits in the kidneys were not reduced in irinotecan-treated mice, subendothelial immune deposits were considerably diminished, suggesting a prevention of glomerular basement membrane disruption. This effect was accompanied by increased rates of ssDNA breaks and inhibition of renal cell apoptosis being different to what is known about irinotecan in anticancer therapy. In conclusion, our data provide evidence that irinotecan might represent an entirely new strategy for the treatment of systemic lupus erythematosus.

PU.1 is linking the glycolytic enzyme HK3 in neutrophil differentiation and survival of APL cells

The transcription factor PU.1 is a master regulator of myeloid differentiation and function. On the other hand, only scarce information is available on PU.1-regulated genes involved in cell survival. We now identified the glycolytic enzyme hexokinase 3 (HK3), a gene with cytoprotective functions, as transcriptional target of PU.1. Interestingly, HK3 expression is highly associated with the myeloid lineage and was significantly decreased in acute myeloid leukemia patients compared with normal granulocytes. Moreover, HK3 expression was significantly lower in acute promyelocytic leukemia (APL) compared with non-APL patient samples. In line with the observations in primary APL patient samples, we observed significantly higher HK3 expression during neutrophil differentiation of APL cell lines. Moreover, knocking down PU.1 impaired HK3 induction during neutrophil differentiation. In vivo binding of PU.1 and PML-RARA to the HK3 promoter was found, and PML-RARA attenuated PU.1 activation of the HK3 promoter. Next, inhibiting HK3 in APL cell lines resulted in significantly reduced neutrophil differentiation and viability compared with control cells. Our findings strongly suggest that HK3 is: (1) directly activated by PU.1, (2) repressed by PML-RARA, and (3) functionally involved in neutrophil differentiation and cell viability of APL cells.

A systematic review of the survival and complication rates of implant-supported fixed dental prostheses (FDPs) after a mean observation period of at least 5 years

The objective of this systematic review was to assess the 5- and 10-year survival of implant-supported fixed dental prostheses (FDPs) and to describe the incidence of biological and technical complications.

Systematic review of the survival rate and the incidence of biological, technical, and aesthetic complications of single crowns on implants reported in longitudinal studies with a mean follow-up of 5 years

To assess the 5-year survival of implant-supported single crowns (SCs) and to describe the incidence of biological, technical, and aesthetic complications. The focused question was: What is the survival rate of implants supporting single crowns and implant-supported crowns with a mean follow-up of 5 years and to which extent do biological, technical, and aesthetic complications occur?

17Beta-estradiol affects the response of complement components and survival of rainbow trout (Oncorhynchus mykiss) challenged by bacterial infection

Research on the endocrine role of estrogens has focused on the reproductive system, while other potential target systems have been less studied. Here, we investigated the possible immunomodulating role of 17beta-estradiol (E2) using rainbow trout (Oncorhynchus mykiss) as a model. The aims of the study were to examine a) whether estrogens can modulate immune gene transcription levels, and b) whether this has functional implications for the resistance of trout towards pathogens. Trout were reared from fertilization until 6 months of age under (1) control conditions, (2) short-term E2-treatment (6-month-old juveniles were fed a diet containing 20 mg E2/kg for 2 weeks), or c) long-term E2-treatment (twice a 2-h-bath-exposure of trout embryos to 400 mug 17beta-estradiol (E2)/L, followed by rearing on the E2-spiked diet from start-feeding until 6 months of age). Analysis of plasma estrogen levels indicated that the internal estrogen concentrations of E2-exposed fish were within the physiological range and analysis of hepatic vitellogenin mRNA levels indicated that the E2 administration was effective in activating the endogenous estrogen receptor pathway. However, expression levels of the hepatic complement components C3-1, C3-3, and Factor H were not affected by E2-treatment. In a next step, 6-month-old juveniles were challenged with pathogenic bacteria (Yersinia ruckeri). In control fish, this bacterial infection resulted in significant up-regulation of the mRNA levels of hepatic complement genes (C3-1, C3-3, Factor B, Factor H), while E2-treated fish showed no or significantly lower up-regulation of the complement gene transcription levels. Apparently, the E2-treated trout had a lower capacity to activate their immune system to defend against the bacterial infection. This interpretation is corroborated by the finding that survival of E2-treated fish under bacterial challenge was significantly lower than in the control group. In conclusion, the results from this study suggest that estrogens are able to modulate immune parameters of trout with functional consequences on their ability to cope with pathogens.