Biomechanical study of thoracolumbar junction fixation devices with different diameter dual-rod systems

2006 ◽  
Vol 4 (3) ◽  
pp. 206-212 ◽  
Author(s):  
Ung-Kyu Chang ◽  
Jesse Lim ◽  
Daniel H. Kim
Keyword(s):  
Biomechanical Testing ◽  
Load Sharing ◽  
Biomechanical Study ◽  
Compression Force ◽  
Mean Values ◽  
Fixation Devices ◽  
Thoracolumbar Region ◽  
Rod System ◽  
The Mean

Object Advances in the design of a smaller-diameter rod system for use in the thoracolumbar region prompted the authors to undertake this biomechanical study of two different thoracolumbar implants. Methods In vitro biomechanical testing was performed using human cadaveric spines. All specimens were loaded to a maximum moment of 5 Nm with 300-N axial preload in six modes of motion. Two types of anterior implants with different rod diameters were applied to intact T10–12 specimens in two groups. The loading was repeated and the range of motion (ROM) was measured. A T-11 corpectomy was then performed and a strain gauge–mounted carbon fiber stackable cage was implanted. The ROM and compression force on the cage were measured, and the mean values were compared between these two groups. With stabilization of the intact spine, ROM decreased least in extension and greatest in bending compared with the intact specimens. After corpectomy and stabilization, ROM increased in extension by 104.89 ± 53.09% in specimens with a 6.35-mm rod insertion and by 83.81 ± 16.96% in those with a 5.5-mm rod, respectively; in flexion, ROM decreased by 26.98 ± 27.43% (6.35 mm) and by 9.59 ± 15.42% (5.5 mm), respectively; and in bending and rotation, both groups each showed a decrease in ROM. The load sharing of the cage was similar between the two groups (the 6.35-mm compared with 5.5-mm rods): 47.44 and 44.73% (neutral), 49.16 and 39.02% (extension), 61.90 and 56.88% (flexion), respectively. Conclusions There were no statistical differences in the ROM and load sharing of the cage when either the 6.35-or 5.5-mm-diameter dual-rod was used.

scholarly journals Survey of Phenolic Acids, Flavonoids and In Vitro Antioxidant Potency Between Fig Peels and Pulps: Chemical and Chemometric Approach

Molecules ◽  
2021 ◽  
Vol 26 (9) ◽  
pp. 2574
Author(s):  
Lahcen Hssaini ◽  
Francisca Hernandez ◽  
Manuel Viuda-Martos ◽  
Jamal Charafi ◽  
Rachid Razouk ◽  
...  
Keyword(s):  
Phenolic Acids ◽  
Radical Scavenging ◽  
Fruit Peel ◽  
Mean Values ◽  
Local Cultivar ◽  
Ic50 Values ◽  
The Mean ◽  
Lipid Peroxidation Inhibition ◽  
Almost All

In the present study, chromatic coordinates, phenolic acids, flavonoids and antioxidant capacity assessed by 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonate (ABTS) and lipid peroxidation inhibition capacity (LPIC) essays and their relative IC50 were investigated in 25 fig cultivars growing in Morocco. The aims of this study were to determine (i) the variation in these compounds among light and dark-colored cultivars, (ii) their partitioning between fruit peel and pulp and (iii) to display network connections among these variables. Twelve phenolic compounds (PCs) were isolated in peel extract versus eight in pulp samples. Anthocyanins, mainly cyanidin-3,5-diglucoside and cyanidin-3-O-rutinoside, were the predominant compounds in peels, where the mean concentrations were 75.90 ± 18.76 and 77.97 ± 18.95 µg/g dw, respectively. On the other hand, (−)-epicatechin and cyanidin-3-O-rutinoside were the major compounds in the pulp extracts, where the mean values were 5.23 ± 4.03 and 9.01 ± 5.67 µg/g dw, respectively. A two-dimensional hierarchically clustered heatmap was applied to the dataset to explore correlations in the dataset and similarities between cultivars, without dimensionality reduction. Results showed that anthocyanins, particularly pelargonidin-3-O-rutinoside, cyanidin-3,5-diglucoside and cyanidin-3-O-rutinoside, were the main contributors to the peels’ free radical scavenging capacity. This capacity was particularly higher in the peel of dark-colored figs compared to the fruit pulp. The local cultivar “INRA 1301” showed the most promising phenolic profile due to its very high levels of almost all detected PCs, especially (−)-epicatechin, quercetin-3-O-rutinoside, quercetin-3-O-glucoside, cyanidine-3,5-diglucoside, cyanidine-3-O-rutinoside and pelargonidin-3-O-rutinoside (54.66, 141.08, 35.48, 494.08, 478.66, 12.56 µg/g dw, respectively). Having the darkest figs in the collection (L* = 25.72, c* = 22.09 and h° = 20.99), this cultivar has also combined promising IC50 values, which were of 19.85, 40.58 and 124.78 µg/mL for DPPH, ABTS and LPIC essays, respectively.

Granulokinetics in normal dogs

1964 ◽  
Vol 206 (1) ◽  
pp. 83-88 ◽  
Author(s):  
S. O. Raab ◽  
J. W. Athens ◽  
O. P. Haab ◽  
D. R. Boggs ◽  
H. Ashenbrucker ◽  
...  
Keyword(s):  
Whole Blood ◽  
Turnover Rate ◽  
Half Time ◽  
Total Blood ◽  
Mean Values ◽  
Hexadimethrine Bromide ◽  
The Mean ◽  
Blood Granulocyte ◽  
Number Of Cells

Dog granulocytes were labeled in vitro with radioactive diisopropylfluorophosphate (DFP32) and then returned to the circulation of the donor. Granulocytes were separated from whole blood by utilizing hexadimethrine bromide as the sedimenting agent and saponin as a lysing agent. The labeled granulocytes disappeared from the circulation in an exponential fashion with a mean (±1 sd) half-time disappearance of 5.6 ± 0.95 hr. The size of the total blood granulocyte ( TBGP), circulating granulocyte ( CGP), and marginal granulocyte ( MGP) pools, and the granulocyte turnover rate ( GTR) were measured in 31 normal, unanesthetized dogs. The mean values ± 1 sd, expressed as number of cells x107/kg body wt., were as follows: TBGP, 102 ± 34.8; CGP, 54 ± 20.7; MGP, 48 ± 23.4; and GTR, 305 ± 111.5 cells/kg day. The values observed in anesthetized and in unanesthetized, splenectomized dogs were not significantly different from the above values.

Biomechanical Assessment of a PEEK Rod System for Semi-Rigid Fixation of Lumbar Fusion Constructs

2011 ◽  
Vol 133 (8) ◽  
Author(s):  
Matthew F. Gornet ◽  
Frank W. Chan ◽  
John C. Coleman ◽  
Brian Murrell ◽  
Russ P. Nockels ◽  
...  
Keyword(s):  
Lumbar Fusion ◽  
Dynamic Performance ◽  
Load Sharing ◽  
Axial Rotation ◽  
Rigid Fixation ◽  
Peek Rods ◽  
Significant Difference ◽  
Flexion Extension ◽  
Rod System

The concept of semi-rigid fixation (SRF) has driven the development of spinal implants that utilize nonmetallic materials and novel rod geometries in an effort to promote fusion via a balance of stability, intra- and inter-level load sharing, and durability. The purpose of this study was to characterize the mechanical and biomechanical properties of a pedicle screw-based polyetheretherketone (PEEK) SRF system for the lumbar spine to compare its kinematic, structural, and durability performance profile against that of traditional lumbar fusion systems. Performance of the SRF system was characterized using a validated spectrum of experimental, computational, and in vitro testing. Finite element models were first used to optimize the size and shape of the polymeric rods and bound their performance parameters. Subsequently, benchtop tests determined the static and dynamic performance threshold of PEEK rods in relevant loading modes (flexion-extension (F/E), axial rotation (AR), and lateral bending (LB)). Numerical analyses evaluated the amount of anteroposterior column load sharing provided by both metallic and PEEK rods. Finally, a cadaveric spine simulator was used to determine the level of stability that PEEK rods provide. Under physiological loading conditions, a 6.35 mm nominal diameter oval PEEK rod construct unloads the bone-screw interface and increases anterior column load (approx. 75% anterior, 25% posterior) when compared to titanium (Ti) rod constructs. The PEEK construct’s stiffness demonstrated a value lower than that of all the metallic rod systems, regardless of diameter or metallic composition (78% < 5.5 mm Ti; 66% < 4.5 mm Ti; 38% < 3.6 mm Ti). The endurance limit of the PEEK construct was comparable to that of clinically successful metallic rod systems (135N at 5 × 106 cycles). Compared to the intact state, cadaveric spines implanted with PEEK constructs demonstrated a significant reduction of range of motion in all three loading directions (> 80% reduction in F/E, p < 0.001; > 70% reduction in LB, p < 0.001; > 54% reduction in AR, p < 0.001). There was no statistically significant difference in the stability provided by the PEEK rods and titanium rods in any mode (p = 0.769 for F/E; p = 0.085 for LB; p = 0.633 for AR). The CD HORIZON® LEGACY™ PEEK Rod System provided intervertebral stability comparable to currently marketed titanium lumbar fusion constructs. PEEK rods also more closely approximated the physiologic anteroposterior column load sharing compared to results with titanium rods. The durability, stability, strength, and biomechanical profile of PEEK rods were demonstrated and the potential advantages of SRF were highlighted.

scholarly journals Some Physiological Factors Affecting the Binding of Cortisol by Human Plasma Proteins

1977 ◽  
Vol 14 (1-6) ◽  
pp. 35-38 ◽  
Author(s):  
J. D. Few ◽  
J. R. Haspineall
Keyword(s):  
Steady State ◽  
Human Plasma ◽  
Plasma Proteins ◽  
Gel Filtration ◽  
Physiological Factors ◽  
Mean Values ◽  
Factors Affecting ◽  
Free Cortisol ◽  
The Mean

Steady-state gel filtration has been used to study the binding of cortisol to human plasma proteins in vitro. Raising the temperature from 37°C to 41°C results in the mean proportion of free (non-protein-bound) cortisol rising approximately from 7% to 11%. Addition of cortisol to plasma ≡ 275 nmol/l) also increased the proportion of free cortisol by approximately 50%. Cortisone is less strongly bound to plasma proteins than cortisol. The mean values (±S.D.) for five samples were free cortisol 8.4 ± 1.1% and free cortisone 26.0±3.8%.

scholarly journals THE GROWTH RATE PHENOTYPIC PROPERTY OF MYCOBACTERIUM TUBERCULOSIS CLINICAL STRAINS: DEPENDENCE ON TUBERCULOSIS LOCALIZATION, TREATMENT, DRUG SUSCEPTIBILITY

2018 ◽  
Vol 8 (2) ◽  
pp. 175-186
Author(s):  
O. A. Manicheva ◽  
M. Z. Dogonadze ◽  
N. N. Melnikova ◽  
B. I. Vishnevskiy ◽  
S. A. Manichev
Keyword(s):  
Growth Rate ◽  
Pulmonary Tuberculosis ◽  
Bacterial Load ◽  
Phenotypic Properties ◽  
Extra Pulmonary Tuberculosis ◽  
Mean Values ◽  
Clinical Strains ◽  
The Mean ◽  
Strain H37rv

The phenotypic properties of the M. tuberculosis strains obtained from patients with pulmonary or extra-pulmonary tuberculosis are  determined by a complex set of factors: the genetic characteristics  of the pathogen, its ability to adapt in vivo and in vitro, the influence of the host’s immune system and chemotherapy. The growth rate as  the phenotypic property is the most accessible for the study of the  host-pathogen relationships at the level of host/strain population  interactions. The aim of the study is to assess in vitro of the growth  rate of M. tuberculosis strains isolated from patients with pulmonary  and extra-pulmonary tuberculosis: untreated and treated (with  surgical and non-surgical treatment) and also sensitive and resistant isolates in comparison with the reference strain H37Rv. To estimate  the growth rate of 116 clinical isolates we have used the modified  method originally developed by von Groll and co-authors: to get the  bacteria growth curve the fluorescence intensity of growing strains  (with indicator resazurin) has been measured daily for 8 days in 96- well plate. The growth rate is determined as the slope of the growth  curve. The mean values of the growth rate have been calculated in  the following groups of patients: 1 — untreated patients with  pulmonary tuberculosis (PT), respiratory material; 2 — non-surgical  treated PT patients, respiratory material; 3 — surgical treated PT  patients (mainly with chronic and hyperchronic process), respiratory  material; 4 — patients like in 3rd group, surgical material; 5 — bone  and joint tuberculosis (BJT), surgical material. In addition, groups of  sensitive and resistant strains have been examined, but there are no  significant differences in growth rates. It has been obtained that  the growth rate of strains isolated from the PT patients is higher than in BJT patients: it can be explained less favorable  conditions for the pathogen vegetation in the BJT. In the case of a  closed tuberculous lesion where the pathogen transmission to  another host is impossible, then the selection of strains with the  property to survive in the tissues of the osteoarticular system is  impossible too, therefor it should be observed only an adaptation of  the pathogen strain population to the individual host. The growth  rate of isolates from untreated PT patients is higher than that of the  treated ones. Comparison of the growth parameters of only MDR  strains 1–5 groups to eliminate the influence of the  sensitivity/resistance has resulted in the same conclusions. We  suggest that the decrease in the growth rate of strains from the  treated PT patients is in not only result of the treatment, but also is  conditioned by adaptation of the pathogen to its external  environment, which is the internal environment of the  macroorganism. To confirm this assumption, the bacterial load of  1,083 diagnostic specimens grouped in a similar manner has been  estimated, taking into account only MDR/XDR strains. In the group  of treated patients the frequency of high bacterial load (CFU ≥ 100)  reached 52.5–63.8% that shows the conserved fitness of bacteria in  such patients. The mean values of the growth rate of the strain  H37Rv non-adapted to the macroorganism (due to numerous  passages on artificial media) are higher than in all groups of clinical  strains. Thus, heterogeneity of phenotypic properties of M.  tuberculosis clinical strains on the basis of growth rate has been  obtained. The growth rate of M. tuberculosis clinical strains is  depended on the tuberculosis localization (PT, BJT) and on the joint  effect of patient treatment and pathogen adaptation to the host. 

scholarly journals Serial In Vitro Bone Marrow Culture in Acute Lymphocytic Leukemia

Blood ◽  
1973 ◽  
Vol 42 (5) ◽  
pp. 687-699 ◽  
Author(s):  
M. J. Duttera ◽  
J. M. Bull ◽  
J. D. Northup ◽  
E. S. Henderson ◽  
E. D. Stashick ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Acute Lymphocytic Leukemia ◽  
Colony Growth ◽  
Lymphocytic Leukemia ◽  
Leukemic Cells ◽  
Mean Values ◽  
Bone Marrow Cultures ◽  
The Mean ◽  
Nonlinear Fashion

Abstract Serial in vitro bone marrow cultures have been done on eight patients with acute lymphocytic leukemia. Colony-forming activity shows a rapid recovery from low values into the normal range in all patients who achieved stable remissions. Mean values for the stimulated cultures remained stable throughout consolidation, whereas the mean values for the unstimulated cultures declined during the same period. Relapse in two patients was preceded or accompanied by a concomitant decline in colony growth. Colony forming activity appears to be inhibited in a nonlinear fashion by increasing numbers of leukemic cells.

scholarly journals In Vitro Study on Bone Heating during Drilling of the Implant Site: Material, Design and Wear of the Surgical Drill

Materials ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1921 ◽  
Author(s):  
Juan Carlos Bernabeu-Mira ◽  
Hilario Pellicer-Chover ◽  
Miguel Peñarrocha-Diago ◽  
David Peñarrocha-Oltra
Keyword(s):  
Stainless Steel ◽  
Axial Loading ◽  
In Vitro Study ◽  
Material Design ◽  
Diamond Like Carbon ◽  
Thermal Variation ◽  
Mean Values ◽  
Carbon Coated ◽  
The Mean

Objective: An in vitro study was made to compare mean thermal variation according to the material, design and wear of the surgical drills used during dental implant site preparation. Material and methods: Three study groups (stainless steel drills with straight blades; diamond-like carbon-coated drills with straight blades; and diamond-like carbon-coated drills with twisted blades) were tested to compare material, design and wear of the surgical drill in terms of overall mean values (complete sequence of drills) and specific mean values (each drill separately). The groups comprised four drills: initial, pilot, progressive and final drill. Implant site configuration was performed through an intermittent and gradual drilling technique without irrigation at 800 rpm in standardized synthetic blocks. Maximum axial loading of two kilograms was controlled by an automatic press. Each surgical drill was submitted to 50 drillings and was sterilized every five uses. A thermographic camera analyzed the mean thermal changes. The software-controlled automatic press kept systematic drilling, axial loading and operational speed constant without any human intervention. Student’s t-test, ANOVA and multiple linear regression models were performed. The level of significance was 5% (p = 0.05). Results: The overall mean comparison between the stainless steel and diamond-like carbon-coated materials showed no statistically significant differences (p > 0.05), though specific mean comparison showed statistically significant differences between the drills of the different groups (p < 0.05). The twisted blades exhibited less overall and specific mean thermal variation than straight blades for the progressive and final drills (p < 0.01). In addition, the initial and pilot drills showed a greater mean thermal change than the progressive and final drills. The mean thermal variation was seen to increase during the 50 drillings. Conclusions: Within the limitations of this study, it can be concluded that the drill material did not significantly influence the overall mean thermal variation except for the pilot drill. The drill design affected overall and specific mean thermal variation since the twisted blades heated less than the straight blades. The initial and pilot drills increased the specific mean thermal variation with respect to the progressive and final drills. In addition, all drills in each group produced a gradual increase in mean temperature during the 50 drillings.

scholarly journals Comparative in vitro study of the cleaning efficacy of AirFloss ultra and I-Prox Sulcus brushes in an orthodontic phantom model

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Hanna Boes ◽  
Sören Brüstle ◽  
Gholamreza Danesh ◽  
Stefan Zimmer ◽  
Mozhgan Bizhang
Keyword(s):  
In Vitro Study ◽  
White Spot Lesions ◽  
Mean Values ◽  
Phantom Model ◽  
Before And After ◽  
Tooth Surfaces ◽  
The Mean ◽  
Post Hoc ◽  
Cleaning Efficacy

AbstractPreventing biofilm-related risks such as gingivitis and white spot lesions during orthodontic treatments is very challenging. The cleaning efficiencies of AirFloss Ultra and I-Prox P sulcus brushes were evaluated using an orthodontic phantom model. After attaching brackets onto black-coated maxillary KaVo teeth, a plaque substitute was applied. The evaluated tooth surfaces were divided into two areas. Cleaning was performed with an AirFloss Ultra with two (A-2) or four (A-4) sprays or an I-Prox P for two (I-2) or four (I-4) seconds. Images before and after cleaning were digitally subtracted, and the percentage of fully cleaned surfaces was determined (Adobe Photoshop CS5, ImageJ). Statistical analysis was performed by ANOVA and post hoc tests with Bonferroni correction (SPSS 25, p < 0.05). The mean values of total cleaning efficacy were 26.87% for I-2, 43.73% for I-4, 34.93%, for A-2 and 56.78% for A-4. The efficacy was significantly higher for A-4 than for A-2, I-4, and I-2. There were significant differences between the four groups. Repeated cleaning led to an improved result. Within the study limitations, the AirFloss Ultra with four sprays proved to be more efficient than the sulcus brush I-Prox P for cleaning.

Biomechanical evaluation of a non-locking pre-manufactured loop suture technique compared to a three-loop pulley suture in a canine calcaneus tendon avulsion model

2016 ◽  
Vol 29 (02) ◽  
pp. 131-135 ◽  
Author(s):  
Anna Dunlap ◽  
Thomas McNicholas ◽  
Stanley Kim
Keyword(s):  
Surgical Repair ◽  
Suture Technique ◽  
Biomechanical Study ◽  
Gap Formation ◽  
Calcaneal Tendon ◽  
Polypropylene Suture ◽  
Biomechanical Evaluation ◽  
The Mean ◽  
Tendon Avulsion

Summary Objective: The purpose of this cadaveric study was to compare the strength of a non-locking pre-manufactured loop (Speed -Whip™ [SW]) suture pattern using Fiber-wire® with the three-loop pulley (TLP) suture pattern using polypropylene for the surgical repair of canine calcaneal tendon avulsion injuries. Methods: In vitro biomechanical study using 22 paired tendons collected from 11 canine cadavers. Paired tendons were repaired with either a SW suture pattern using Fiberloop® suture or a TLP suture pattern using polypropylene suture. Tensile loads required to create a 1 mm gap, 3 mm gap, and construct failure were measured. Results: The mean loads to achieve a 1 mm gap in the TLP and SW constructs were not significantly different. Gap formation at 3 mm occurred at significantly lower loads for the SW (106.4 ± 21.5N) than for the TLP (127.2 ± 27.5N) (p = 0.05). The mean loads to construct failure for the TLP (172.8 ± 39.4N) and SW (131.3 ± 34.3N) were significantly different (p = 0.001). Clinical significance: The TLP with polypropylene suture is superior to the SW using Fiberloop® at resistance to 3 mm gap formation.

An In Vitro Biomechanical Study Comparing the Spiral Linking Technique Against the Pulvertaft Weave for Tendon Repair

2007 ◽  
Vol 32 (4) ◽  
pp. 377-381 ◽  
Author(s):  
Y. I. KULIKOV ◽  
S. DODD ◽  
S. GHEDUZZI ◽  
A. W. MILES ◽  
G. E. B. GIDDINS
Keyword(s):  
Testing Machine ◽  
Peak Load ◽  
Tendon Repair ◽  
Tensile Loading ◽  
Biomechanical Study ◽  
The Other ◽  
Instron Testing Machine ◽  
Peak Loads ◽  
The Mean

A new spiral linking technique for tendon repair in which one end of the tendon is spiralled around the other end has been developed. Using pig trotter extensor tendons, the Pulvertaft weave technique was compared with this new technique. Twenty-five repairs using each technique were tested by tensile loading with an Instron testing machine. The spiral linking technique matched the strength of Pulvertaft method: the mean peak loads were 102 and 105 N, respectively. The Pulvertaft weave was stiffer than the spiral linking technique: mean stiffness of 11.1 and 6.7 N/mm, respectively. The spiral linking technique also absorbed considerably more energy: energy absorbed prior to failure to 90% of peak load, 1.75 and 1.13 kN mm, respectively. In conclusion, the spiral linking technique appears as strong as the Pulvertaft weave and we believe it is easier to perform.

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