358 research outputs found
The in vitro viability and growth of fibroblasts cultured in the presence of different bone grafting materials (NanoBone® and Straumann Bone Ceramic®)
Different clinical applications, including dentistry, are making increasing demands
on bone grafting material. In the present study we have analysed the viability,
proliferation and growth characteristics of fibroblasts cultured in vitro together
with two different bone grafting materials, NanoBone® and Straumann Bone
Ceramic®, over a period of 24 and 28 days respectively. Viability was measured
at least every 72 hours by using the alamarBlue assay, a test that measures
quantitatively cell proliferation and viability but does not require cell fixation or
extraction. After one week of culture fibroblast viability was as high as in controls
for both grafting materials and remained high (> 90%) for the duration of
the experiment. Cell growth was evaluated microscopically. Scanning electron
microscopy revealed a dense fibroblast growth at the surface of both bone grafting
materials after three weeks of in vitro culture. Generally, our in vitro analyses
contribute to further insights into cell - scaffold interactions
The biodegradation of hydroxyapatite bone graft substitutes in vivo
Hydroxyapatite (HA) ceramics are widely used for bone reconstruction. They are
osteoconductive and serve as structural scaffolds for the deposition of new bone.
Generally, scaffold materials should be degradable as they affect the mechanical
properties of the reconstructed bone negatively. Degradation by osteoclasts
during the bone remodelling process is desirable but often does not take place.
In the current study we analysed by light microscopy the degradation of two
granular HA implants in critically sized defects in the mandibula of Goettingen
mini-pigs five weeks after implantation. Bio-Oss® consists of sintered bovine
bone and NanoBone® is a synthetic HA produced in a sol-gel process in the
presence of SiO2. We found that both biomaterials were degraded by osteoclasts
with ruffled borders and acid phosphatase activity. The osteoclasts created
resorption lacunae and resorptive trails and contained mineral particles. Frequently,
resorption surfaces were in direct contact with bone formative surfaces
on one granule. Granules, especially of NanoBone®, were also covered by osteoclasts
if located in vascularised connective tissue distant from bone tissue.
However, this usually occurred without the creation of resorption lacunae. The
former defect margins consisted of newly formed bone often without remnants
of bone substitutes. Our results show that the degradation of both biomaterials
corresponds to the natural bone degradation processes and suggest the possibility
of complete resorption during bone remodelling
The survival and proliferation of fibroblasts on orthodontic miniscrews with different surface treatment: an in vitro study
It is of fundamental importance for prosthodontic and orthodontic applications
that there is a short osseointegration time of dental implants without inflammation
of the surrounding tissue. In addition to the chemical properties of the
implant material, the surface morphology is an equally critical parameter. The
objective of this work was to study the effect of two simple surface treatments
on the survival and proliferation of fibroblasts.
Three groups of orthodontic miniscrews (Mondeal®) were used. One group was
given an airflow (EMS, Schweiz) treatment, the second was sand-blasted in the
area of the threading and a third group served as a control. After preparation
sterilised screws were cultured in vitro with fibroblasts (L-929). The metabolic
cell activity on the implant surface was determined after 24, 48 and 120 hours
using the alamarBlue assay and a count of DAPI labelled fibroblasts was performed
with a fluorescence microscope.
After 24 hours, but not at 48 hours and 120 hours, the metabolic activity of the
fibroblasts was slightly decreased for the airflow screw group. Generally, no
significant difference was found regarding metabolic activity and proliferation
of fibroblasts within the different groups
Wound management after the application of bone grafting substitutes in the orofacial region
Surgical dressing after the application of bone grafting material depends on the
type and size of the defect. A complete and tension-free wound closure has
proved to be successful. In this context the infection problem needs special
attention. Bone graft substitutes with an adequate surface structure, porosity
and chemical properties, in combination with sufficient blood circulation, hold
osteoconductive potential. They serve as a guide rail for the osteoblast-induced
formation of new bone tissue, which at best may lead to complete replacement
of the grafting material
Bone functions and the requirements for bone grafts and substitutes in the orofacial region
Bone is the largest calcium storage, has distinctive plasticity and adaptability and
is part of the supporting tissue. An adequate composition is thus necessary. The
bone matrix consists of organic and anorganic structures. Osteoblasts, osteoclasts
and osteocytes are responsible for bone formation, resorption and metabolism.
The periosteum, endosteum and bone tissue are a functional unit and provide
protection, nutrition and growth. Bone is subject to continuous remodelling
Critical considerations on the diagnostic appraisal, adaptation and remodelling of bone graft substitutes
The diagnostic assessment of skeletal defects has a long-standing tradition. As
a result of the development of new bone grafting materials, the demands on
diagnostic assessment have also increased. The mode and quality of diagnostic
appraisal are crucial to further clinical use and outcome prediction. Alongside
traditional clinical and biological techniques, molecular biological methods have
gained a broad scope of application and will be used even more frequently in
the future
Converting simulated total dry matter to fresh marketable yield for field vegetables at a range of nitrogen supply levels
Simultaneous analysis of economic and environmental performance of horticultural crop production requires qualified assumptions on the effect of management options, and particularly of nitrogen (N) fertilisation, on the net returns of the farm. Dynamic soil-plant-environment simulation models for agro-ecosystems are frequently applied to predict crop yield, generally as dry matter per area, and the environmental impact of production. Economic analysis requires conversion of yields to fresh marketable weight, which is not easy to calculate for vegetables, since different species have different properties and special market requirements. Furthermore, the marketable part of many vegetables is dependent on N availability during growth, which may lead to complete crop failure under sub-optimal N supply in tightly calculated N fertiliser regimes or low-input systems. In this paper we present two methods for converting simulated total dry matter to marketable fresh matter yield for various vegetables and European growth conditions, taking into consideration the effect of N supply: (i) a regression based function for vegetables sold as bulk or bunching ware and (ii) a population approach for piecewise sold row crops. For both methods, to be used in the context of a dynamic simulation model, parameter values were compiled from a literature survey. Implemented in such a model, both algorithms were tested against experimental field data, yielding an Index of Agreement of 0.80 for the regression strategy and 0.90 for the population strategy. Furthermore, the population strategy was capable of reflecting rather well the effect of crop spacing on yield and the effect of N supply on product grading
Diverse soil carbon dynamics expressed at the molecular level
The stability and potential vulnerability of soil organic matter (SOM) to global change remains incompletely understood due to the complex processes involved in its formation and turnover. Here we combine compound-specific radiocarbon analysis with fraction-specific and bulk-level radiocarbon measurements in order to further elucidate controls on SOM dynamics in a temperate and sub-alpine forested ecosystem. Radiocarbon contents of individual organic compounds isolated from the same soil interval generally exhibit greater variation than those among corresponding operationally-defined fractions. Notably, markedly older ages of long-chain plant leaf wax lipids (n-alkanoic acids) imply that they reflect a highly stable carbon pool. Furthermore, marked 14C variations among shorter- and longer-chain n-alkanoic acid homologues suggest that they track different SOM pools. Extremes in SOM dynamics thus manifest themselves within a single compound class. This exploratory study highlights the potential of compound-specific radiocarbon analysis for understanding SOM dynamics in ecosystems potentially vulnerable to global change
Auditory hallucinations and migraine of possible brainstem origin
10.1007/s10194-011-0355-zJournal of Headache and Pain125573-57
Lignin biomarkers as tracers of mercury sources in lakes water column
This study presents the role of specific terrigenous organic compounds as important vectors of mercury (Hg) transported from watersheds to lakes of the Canadian boreal forest. In order to differentiate the autochthonous from the allochthonous organic matter (OM), lignin derived biomarker signatures [Lambda, S/V, C/V, P/(V ? S), 3,5-Bd/V and (Ad/Al)v] were used. Since lignin is exclusively produced by terrigenous plants, this approach can give a non equivocal picture of the watershed inputs to the lakes. Moreover, it allows a characterization of the source of OM and its state of degradation. The water column of six lakes from the Canadian Shield was sampled monthly between June and September 2005. Lake total dissolved Hg concentrations and Lambda were positively correlated, meaning that Hg and ligneous inputs are linked (dissolved OM r2 = 0.62, p\0.0001; particulate OM r2 = 0.76, p\0.0001). Ratios of P/(V ? S) and 3,5-Bd/V from both dissolved OM and particulate OM of the water column suggest an inverse relationship between the progressive state of pedogenesis and maturation of the OM in soil before entering the lake, and the Hg concentrations in the water column. No relation was found between Hg levels in the lakes and the watershed flora composition—angiosperm versus gymnosperm or woody versus non-woody compounds. This study has significant implications for watershed management of ecosystems since limiting fresh terrestrial OM inputs should reduce Hg inputs to the aquatic systems. This is particularly the case for largescale land-use impacts, such as deforestation, agriculture and urbanization, associated to large quantities of soil OM being transferred to aquatic systems
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