Aim Information on the community composition, structure, and dynamics of epiphyte vegetation is scarce. A survey of the epiphytes occurring on all individuals of one particular host tree species in a well-studied neotropical research site allowed us a comparison of the epiphyte flora of this tree with the local epiphyte flora, the analysis of spatial distribution patterns and the use of these patterns as indications for changes in time. In the future, our results can be used as a baseline data-set for the direct observation of the long-term dynamics in epiphyte communities. LocationThe study was conducted on Barro Colorado Island (BCI), Panama. MethodsWe recorded all individuals of the vascular epiphytes growing on Annona glabra L., a flood-tolerant, multiple-stemmed tree, which is restricted to the shoreline of BCI. Data on tree biometrics, epiphyte species, and epiphyte abundances were collected for more than 1200 trees. ResultsIn total, we encountered almost 15,000 epiphytic individuals in sixty-eight species, corresponding to more than one third of the entire epiphyte flora of Barro Colorado Island. The component species differed strongly in abundance: the four most important species accounted for >75% of all individuals. In most cases, the same four species were also the first to colonize a tree (=phorophyte). Colonization patterns indicated no replacement of early colonizers by late arrivals. Species richness and epiphyte abundances showed a positive correlation with the size and the density of the host trees. All species showed a highly clumped distribution and the physiognomy of epiphyte communities of individual trees was dominated either by one or several of the four most common species or by a set of frequently co-occurring tank bromeliads. Other species were dominant only in exceptional cases. Most species were always rare. A distance effect on community composition was mostly confined to a local scale with an increased similarity in the species assemblage of stems of a tree v. neighbouring trees. Main conclusionsThe epiphytes on a single small phorophyte species may encompass a surprisingly large proportion of the local epiphyte flora. The observations that most tree crowns are inhabited by a single or only very few species, and that all epiphyte species show highly clumped distributions suggest a predominance of very local dispersal within a tree crown, which is only infrequently interrupted by successful long-distance dispersal between crowns.

Objectives To describe the early biofilm formation over whole dental implants with its micro‐ and macrostructure, using an in vitro multispecies biofilm model. Material and methods Six bacterial strains (Streptococcus oralis, Actinomyces naeslundii, Veillonella parvula, Fusobacterium nucleatum, Porphyromonas gingivalis, and Aggregatibacter actinomycetemcomitans) were used to develop in vitro biofilms over whole titanium implants (growth times 12, 24, 48, 72, 96, and 120 hr). The morphology of biofilms was studied by confocal laser scanning microscopy and scanning electron microscopy, and the bacterial dynamics through quantitative polymerase chain reaction. As primary outcome variable, numbers of each species [colony‐forming units per milliliter (CFU/ml)] at different incubation times were compared using the one‐way analysis of variance and post hoc testing with Bonferroni's correction. Furthermore, implants were fixed in methacrylate stents to reproduce the clinical situation and biofilms were developed and analyzed by scanning electron microscopy. Results Bacteria colonized implants in a short period of time. Biofilms reached a mature state at 96 hr, exhibiting different ratios of live/dead cells depending on their location, being the peaks of the threads the areas harboring more live bacteria. The densities of each bacteria fluctuated in time, reaching its maximum at 96 hr. Even though the coefficients of variation were high, percentages were similar to those published previously using implant surface specimens, rather than whole implants. Conclusion Dental implants can be colonized by different bacterial species, developing into a mature and well‐structured biofilm, which depending on the location may exhibit different degree of bacterial vitality.

Objectives:To compare biofilm formation on whole dental titanium implants with different surface micro-topography. Methods:A multispecies in vitro biofilm model consisting of initial (Streptococcus oralis and Actinomyces naeslundii), early (Veillonella parvula), secondary (Fusobacterium nucleatum) and late colonizers (Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans) was grown for 96 hr on sterile titanium dental implants with either minimal (S a : 0.5-1.0 mm) or moderate-roughness titanium surfaces (S a : 1.1-2.0 mm).The resulting biofilms were studied with Confocal Laser Scanning Microscopy (CLSM) and Scanning Electron Microscope. Concentrations (colony-forming units per mL [CFU/ml]) of each bacterium were measured by quantitative Polymerase Chain Reaction (qPCR) and compared by Student t tests.Results: A biofilm, located mainly at the peak and lateral areas of the implant threads, was observed on both implant surfaces, with a greater biomass and a greater live/dead ratio in moderate-compared to minimal-roughness surface implants. Statistically significant higher values of total bacteria (mean difference = 2.61 × 10 7 CFU/ml; 95% confidence interval -CI [1.91 × 10 6 ; 5.02 × 10 7 ]; p = 0.036), F. Nucleatum (mean difference = 4.43 × 10 6 CFU/ml; 95% CI [1.06 × 10 6 ; 7.80 × 10 6 ]; p = 0.013) andA. actinomycetemcomitans (mean difference = 2.55 × 10 7 CFU/ml; 95% CI [1.07 × 10 7 ; 4.04 × 10 7 ]; p = 0.002), were found in the moderate-compared to minimal-roughness surface dental implants.Conclusions: Implants with moderate-roughness surfaces accumulated more bacterial biomass and significant higher number of pathogenic bacteria (F. nucleatum and A. actinomycetemcomitans), when compared to implants with minimal-roughness surfaces, within a similar biofilm structure.

Spot sign and live-imaged dramatic intracerebral hematoma expansion A 74-year-old man with a history of hypertension presented 1 hour after a sudden onset of a complete right hemisphere syndrome. Noncontrast CT showed a 43-mL right deep intracranial hematoma (figure, A). CT angiography (CTA) performed 10 minutes later, as per our imaging protocol, detected a dramatic hematoma growth up to 84 mL, together with intraventricular extension. A spot sign was apparent (figure, B). By the end of CT scanning, the patient's Glasgow Coma Scale score had dropped to 7. Follow-up CT scan confirmed further hematoma expansion as predicted by the spot sign (figure, C). The spot sign, defined as 1-mm to 2-mm foci of enhancement within a hematoma on CTA source images, is typically located in the periphery of hematomas and suggests the likelihood of expansion. The pathologic basis remains unclear, but may represent primary vessel pathology such as microaneurysms. 1 Alternatively, extravasation of blood within the hematoma could occur, as suggested by slow expansion within the hematoma after contrast, 2 possibly due to secondary vessel disruption by the hematoma. In our case, the spot sign was already present when the hematoma was expanding and predicted further growth, supporting the mechanism of extravasation and contrast leakage related to secondary vessel damage.

No abstract

No abstract