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Sequential osseointegration from osseohealing to osseoremodeling - Histomorphological comparison of novel 3D porous and solid Ti-6Al-4V titanium implants
Full text linkIn the present study, we analyzed the
histological characteristics of osseointegration of an
open-porous Ti-6Al-4V material that was produced in a
space holder method creating a 3-D through-pores
trabecular design that mimics the inhomogeneity and
size relationships of trabecular bone in macro- as well as
microstructure. Pairs of cylindrical implants with a
porosity of 49% and an average pore diameter of 400
µm (PI) or equal sized solid, corundum blasted devices
(SI) as reference were bilaterally implanted press fit in
the lateral condyles of 16 rabbits. Histological
examination was performed after 4 weeks of short-term
osseohealing and 12 weeks of mid-term osseoremodeling and we summarized the criteria for
sequential osseointegration. After 4 weeks, osteoid had
already been largely replaced by mineralized woven
bone in both types of implants but was only represented
to a greater extent in the deeper pores of PI. The cortical
as well as trabecular region showed regular osseohealing
with excessive and spatially undirected formation of
immature woven bone. A dense bone mass was found in
the cortical area, while in the trabecular region the bone
mass was reduced distinctly, presenting large lacuna-like
recesses and a demarcating trabecular structure. The
pores near the implant surface contained more
mineralized woven bone than the deeper pores. After 12
weeks, the osseoremodeling was largely completed with
a physiological maturation to lamellar bone. The newly
formed bone mass increased for PI and SI compared to
the 4-week group and osteoid was only detectable in the
deeper pores. The inhomogeneous trabecular design of
the pores enables an excellent ingrowth of mineralized
lamellar bone after remodeling to a pore depth of 1800
µm, which proves a functional load transfer from the
surrounding bone into the implant. According to the
concept of osseointegration by Branemark and
Albrektsson, the histological evaluation confirms a
successful, superior osseointegration of the presented
porous properties improving long-term implant stability.
The presented study protocol allows an excellent
evaluation and comparison of the sequential
osseointegration from short-term osseohealing to midterm osseoremodeling
Osseointegration of a novel 3D porous Ti-6Al-4V implant material – Histomorphometric analysis in rabbits
Full text linkPorous structure properties are known to
conduct initial and long-term stability of titanium alloy
implants. This study aims to assess the
histomorphometric effect of a 3-D porosity in Ti-6Al-4V
implants (PI) on osseointegration in comparison to solid
Ti-6Al-4V implants (SI). The PI was produced in a
spaceholder method and sintering and has a pore size of
mean 400 µm (50 µm to 500 µm) and mimics human
trabecular bone. Pairs of PI and equal sized SI as
reference were bilaterally implanted at random in the
lateral femoral condyle of 16 Chinchilla-Bastard rabbits.
The animals were sacrificed after 4 and 12 weeks for
histomorphometric analysis. The histomorphometric
evaluation confirmed a successful short-term
osseohealing (4 weeks) and mid-term osseoremodeling
(12 weeks) for both types of implants. The total newly
formed bone area was larger for PI than for SI after 4
and 12 weeks, with the intraporous bone area being
accountable for the significant difference (p<0.05). A
more detailed observation of bone area distribution
revealed a bony accumulation in a radius of ±500 µm
around the implant surface after remodeling. The boneto-implant contact (BIC) increased significantly (p<0.05)
from 4 to 12 weeks (PI 26.23% to 42.68%; SI 28.44% to
47.47%) for both types of implants. Due to different
surface properties, however, PI had a significant
(p<0.05) larger absolute osseous contact (mm) to the
implant circumference compared to the SI (4 weeks:
7.46 mm vs 5.72 mm; 12 weeks: 11.57 mm vs 9.52 mm
[PI vs. SI]). The regional influences (trabecular vs.
cortical) on bone formation and the intraporous
distribution were also presented. Conclusively, the
porous structure and surface properties of PI enable a
successful and regular osseointegration and enhance the
bony fixation compared to solid implants under
experimental conditions
Evaluation of EGFR protein expression by immunohistochemistry using H-score and the magnification rule: Re-analysis of the SATURN study
No full textAbstractIntroductionThe phase III SATURN study demonstrated that first-line maintenance erlotinib extended progression-free survival (PFS) and overall survival (OS) versus placebo in patients with advanced non-small cell lung cancer (NSCLC). Analysis of epidermal growth factor receptor (EGFR) expression by immunohistochemistry (IHC) found no significant interaction between EGFR IHC status and PFS (p=0.63) or OS (p=0.52). The FLEX study of first-line cetuximab plus chemotherapy demonstrated that EGFR IHC expression was predictive of improved OS with cetuximab when assessed by H-score with a magnification rule. This novel method was used to reassess samples from SATURN.MethodsThe H-score method assigned a score of 0–300 to each patient, based on the percentage of cells stained at different intensities viewed at various magnifications. The discriminatory threshold was set at 200, per the FLEX study, and existing samples were re-read and classed as low (H-score<200) or high (≥200) EGFR expression. PFS and OS were re-analyzed based on these new classifications.ResultsIn the overall and EGFR wild-type populations, erlotinib provided a consistent survival benefit versus placebo. Hazard ratios (HRs) in the overall population were similar between EGFR IHC-positive and -negative patients for median PFS (HR 0.68 [95% confidence interval (CI) 0.53–0.86] and 0.76 [95% CI 0.62–0.93], respectively) and OS (HR 0.80 [95% CI 0.62–1.05] and 0.80 [95% CI 0.64–1.01] for IHC-positive and IHC-negative, respectively). In the EGFR wild-type population, HRs were again similar between EGFR IHC-positive and -negative subpopulations for PFS (HR 0.69 [95% CI 0.51–0.95] and 0.84 [95% CI 0.63–1.12], respectively) and OS (HR 0.78 [95% CI 0.55–1.10] and 0.76 [95% CI 0.55–1.05], respectively).ConclusionsThese data suggest that EGFR IHC does not have value as a marker to predict erlotinib benefit in the first-line maintenance setting for advanced NSCLC
ANALYSIS OF PFS AND OS FROM THE SATURN STUDY ACCORDING TO EGFR IHC STATUS USING THE H-SCORE READING METHOD
No full text
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Generation of highly differentiated BHY oral squamous cell carcinoma multicellular spheroids
No full textDispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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