Multiscale Spatial Variability and Stability in the Structure and Diversity of Bacterial Communities Associated with the Kelp Eisenia cokeri in Peru

Ecological communities are structured by a range of processes that operate over a range of spatial scales. While our understanding of such biodiversity patterns in macro-communities is well studied, our understanding at the microbial level is still lacking. Bacteria can be free living or associated with host eukaryotes, forming part of a wider "microbiome," which is fundamental for host performance and health. For habitat forming foundation-species, host-bacteria relationships likely play disproportionate roles in mediating processes for the wider ecosystem. Here, we describe host-bacteria communities across multiple spatial scales (i.e., from 10s of m to 100s of km) in the understudied kelp, Eisenia cokeri, in Peru. We found that E. cokeri supports a distinct bacterial community compared to the surrounding seawater, but the structure of these communities varied markedly at the regional (~480 km), site (1-10 km), and individual (10s of m) scale. The marked regional-scale differences we observed may be driven by a range of processes, including temperature, upwelling intensity, or regional connectivity patterns. However, despite this variability, we observed consistency in the form of a persistent core community at the genus level. Here, the genera Arenicella, Blastopirellula, Granulosicoccus, and Litorimonas were found in >80% of samples and comprised ~53% of total sample abundance. These genera have been documented within bacterial communities associated with kelps and other seaweed species from around the world and may be important for host function and wider ecosystem health in general.

Single-step process to improve the mechanical properties of carbon nanotube yarn

Carbon nanotube (CNT) yarns exhibit low tensile strength compared to conventional high-performance carbon fibers due to the facile sliding of CNTs past one another. Electron beam (e-beam) irradiation was employed for in a single-step surface modification of CNTs to improve the mechanical properties of this material. To this end, CNT yarns were simultaneously functionalized and crosslinked using acrylic acid (AA) and acrylonitrile (AN) in an e-beam irradiation process. The chemical modification of CNT yarns was confirmed by X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and scanning electron microscopy (SEM). The best improvement in mechanical properties was achieved on a sample treated with an aqueous solution of AA and subsequent irradiation. CNT yarn treatment with AA enhanced the strength (444.5 ± 68.4 MPa) by more than 75% and the modulus (21.5 ± 0.6 GPa) by more than 144% as compared to untreated CNT yarn (strength 251 ± 26.5 MPa and modulus 8.8 ± 1.2 GPa).

The nasopalatine canal as an anatomic buttress for implant placement in the severely atrophic maxilla: a pilot study

PURPOSE

The aim of this study was to present an alternative treatment concept for the rehabilitation of the atrophic maxilla that used the nasopalatine canal as an anatomic buttress for dental implant insertion and to assess patient satisfaction with this treatment.

MATERIALS AND METHODS

The inclusion criterion for the study consisted of the presence of severe resorption of the edentulous maxilla (Class V according to the Cawood and Howell classification). In each patient, one implant was positioned in the nasopalatine canal. Additional implants were also placed in the remaining maxillary bone. The patients were followed for a minimum of 2 years after prosthesis connection. Satisfaction with the prosthesis was evaluated after 12 months using a visual analog scale.

RESULTS

Seven patients with severely resorbed edentulous maxillae received a total of seven implants in the nasopalatine buttress and 29 implants posterior to this structure. One of the seven implants in the nasopalatine canal was lost during the osseointegration phase. All patients had stable prostheses at the end of the observation period. Patients were satisfied with comfort and stability, ability to speak, ease of cleaning, and esthetics and function of the prosthesis. Five patients experienced minor sensory alterations during the first weeks after surgery. At the final examination, which took place after a mean of 5 years (range, 3 to 7 years), all patients expressed the presence of normal sensation.

CONCLUSIONS

It appears that implants in the nasopalatine canal may be a viable treatment approach for the rehabilitation of the severely atrophied maxilla. Patients were satisfied with a prosthesis supported by implants in the nasopalatine canal.

Zygomatic implants using the sinus slot technique: clinical report of a patient series

PURPOSE

The management of 5 patients with extreme maxillary atrophy and treatment consisting of maxillary fixed prostheses supported by conventional implants and zygomatic fixations positioned according to the sinus slot technique is reported.

MATERIALS AND METHODS

A total of 16 conventional implants were placed, together with 2 pterygoid implants and 10 zygomatic fixations. In 2 cases zygomatic fixation could not be performed on the alveolar ridge, thus requiring palatal displacement. One patient presented nasogenian ecchymosis. The fixed rehabilitations were either screwed or cemented after 5 to 6 months.

RESULTS

Follow-up from implantation lasted 12 to 18 months, during which the prostheses and implants remained stable and in function.

DISCUSSION

The placement of zygomatic fixations based on the sinus slot technique offers advantages over the conventional technique, though extreme atrophy of the alveolar processes does not allow fixation at the supracrestal level, and complications may develop.

CONCLUSION

While zygomatic fixation is a valid alternative for treating the atrophic jaw, long-term studies are required to confirm its efficacy.

Immediate loading in oral implants. Present situation

The earliest antecedents of immediate loading were introduced by Ledermann in 1979. He placed overdenture in four interforaminal implants on the same day the surgery was carried out. In the original implantological protocol of Brånemark the immediate loading did not appear indicated, currently, it is being presented as a predictable alternative in several studies. We revised different articles on immediate loading from 1997 to 2002. We analysed different variables and concluded that immediate loading produces a success rate in posterior maxilla similar to the differed loading (90-100%). The characteristics of the implant, favourable to immediate loading, are: screw-shaped, with a rough surface, sand blasted and acid etching processed and a minimum length of 10 mm. The initial stability and a micro movement of the implant, inferior to 150 microm and a marginal to the insertion equal or superior to 32 N/cm are defined as a proper osseous. The bruxism stands out as an adverse factor according to several authors.

Immediate implants after extraction. A review of the current situation

Immediate implants are positioned in the course of surgical extraction of the tooth to be replaced. The percentage success of such procedures varies among authors from 92.7-98.0%. The main indication of immediate implantation is the replacement of teeth with pathologies not amenable to treatment. Its advantages with respect to delayed implantation include reduced post-extraction alveolar bone resorption, a shortening of the rehabilitation treatment time, and the avoidance of a second surgical intervention. The inconveniences in turn comprise a general requirement for membrane-guided bone regeneration techniques, with the associated risk of exposure and infection, and the need for mucogingival grafts to seal the socket space and/or cover the membranes. The surgical requirements for immediate implantation include extraction with the least trauma possible, preservation of the extraction socket walls and thorough alveolar curettage to eliminate all pathological material. Primary stability is an essential requirement, and is achieved with an implant exceeding the alveolar apex by 3-5 mm, or by placing an implant of greater diameter than the remnant alveolus. Esthetic emergence in the anterior zone is achieved by 1-3 mm sub-crest implantation. Regarding guided regeneration of the alveolar bone, the literature lacks consensus on the use of membranes and the type of filler material required. While primary wound closure is desirable, some authors do not consider it to be of great relevance.

Marginal peri-implantitis due to occlusal overload. A case report

The etiology of marginal peri-implantitis describes an infectious factor and a biomechanical factor resulting from occlusal overload. Clinical and experimental articles oriented to the biomechanical factor are scarce, so as the studies about the histology associated to periimplantitis. We present a case of marginal peri-implantitis on an implant in the mandibular molar zone caused by occlusal overload, which led to an osseous defect on the marginal crest. The treatment was composed of occlusal adjustment, removal of contaminated surgical tissue, and autogenous bone graft, which varies from the common treatment of infectious peri-implantitis. Histologic analysis of peri-implantitis tissue reveals a juxtaepithelial lympho-plasmocytorious infiltrate and a central zone of dense fibro-connective tissue with scanty inflammatory cells, which differs from the chronic inflammatory tissue associated with infectious peri-implantitis. Clinical and radiographic followup control after 12 months evidenced the remission of the symptoms and bone regeneration on the marginal crest. We consider that in the treatment of marginal peri-implantitis, it is necessary to continue the studies on the histological differences between the infectious types and those that are caused by occlusal overload.

Evaluation of human exposure to ambient PM10 in the metropolitan area of Mexico City using a GIS-based methodology

The main goal of this study was to evaluate the magnitude of outdoor exposure to fine particulate matter (PM10) potentially experienced by the population of metropolitan Mexico City. With the use of a geographic information system (GIS), spatially resolved PM10 distributions were generated and linked to the local population. The PM10 concentration exceeded the 24-hr air quality standard of 150 microg/m3 on 16% of the days, and the annual air quality standard of 50 microg/m3 was exceeded by almost twice its value in some places. The basic methodology described in this paper integrates spatial demographic and air quality databases, allowing the evaluation of various air pollution reduction scenarios. Achieving the annual air quality standard would represent a reduction in the annual arithmetic average concentration of 14 microg/m3 for the typical inhabitant. Human exposure to particulate matter (PM) has been associated with mortality and morbidity in Mexico City; reducing the concentration levels of this pollutant would represent a reduction in mortality and morbidity and the associated cost of such impacts. This methodology is critical to assessing the potential benefits of the current initiative to improve air quality implemented by the Environmental Metropolitan Commission of Mexico City.

Sensitive detection of Helicobacter pylori in gastric aspirates by polymerase chain reaction

The detection of Helicobacter pylori in gastric aspirate was examined by using the polymerase chain reaction (PCR) method for amplifying a specific fragment of the urease gene A. The ability of PCR to amplify H. pylori-specific DNA was analyzed by Southern hybridization with an internal oligonucleotide probe. Twenty-two H. pylori strains from clinical isolates and reference strains were studied, and all H. pylori strains yielded a 356-bp product that hybridized with the oligonucleotide probe, whereas no amplification was evident with 18 non-H. pylori strains. This could detect as little as 50 CFU of H. pylori in pure culture and 0.1 pg of purified chromosomal DNA. A total of 50 dyspeptic patients were examined for the presence of H. pylori by culture, the rapid urease test and histological examination of antral biopsy samples as well as by PCR in gastric juice aspirate samples. The gold standard for the presence of H. pylori was established by minimum concordance of two of three tests performed on biopsy specimens. With this gold standard, 34 of the 50 patients were considered to harbor H. pylori infection. PCR correctly identified 32 (94.1%) of these 34 infected patients. PCR had the best combination of sensitivity and specificity in assessing the correct diagnosis of H. pylori as compared with those of the rapid urease test and culture. Moreover, we established a fast and simple method for use by improvement of DNA extraction. PCR of the gastric aspirate was shown to be a sensitive and specific procedure which may be an attractive alternative to methods currently used for diagnosis of H. pylori infection.

Electron paramagnetic resonance studies of gamma-irradiated corn

Gamma-irradiated corn samples in the range 0.1-2.0 kGy dose range were studied by the EPR technique. The signal consists of one structureless line with a width of 0.82 +/- 0.02 mT and a g-factor of 2.004 +/- 0.002. The intensity of this line shows a linear dependence in this dose range. The corn samples were ground prior to irradiation. Before grinding the samples did not show any EPR signal. After grinding they present a free radical EPR line with the same characteristics as that produced by the gamma rays. The stability of these centers as a function of the temperature and time after irradiation was investigated. Analysis of these results suggest the presence of only one type of radical produced by both the mechanical and irradiation processes.