A New Test Method for in vitro Evaluation of Pedicle Screw Loosening Potential

2021 ◽  
Author(s):  
Otávio T. Pinto ◽  
Isabel F Laforce ◽  
Dimitra V Badra ◽  
Carlos Rodrigo De Mello Roesler
Keyword(s):  
Longitudinal Axis ◽  
Testing Procedure ◽  
Test Method ◽  
Static Testing ◽  
Testing Method ◽  
Pull Out ◽  
Simulated Environment ◽  
Pedicular Screw ◽  
Pedicle Screw Loosening

Abstract This paper proposes a new testing method based on the toggle effect under transverse loads (cranial-caudal) to investigate the loosening potential of pedicular screw designs. A three-step in vitro testing procedure was developed to mimic the loosening mechanism of pedicular screws. Firstly, the pedicular screw of a certain design is inserted into a bone substitute model specifically designed for the test. Secondly, a controlled cyclic cranial-caudal loading is applied transversally to the longitudinal axis of the screw for three ascendent load levels (staircase) by a pre-determined number of load cycles. Lastly, each pedicular screw is adjusted and submitted to axial pull-out quasi-static testing. The results are used to calculate a loosening index that, together with statistical analysis, indicates the potential for loosening of the specific design evaluated. The proposed testing method effectively provides a simulated environment to evaluate the loosening potential of pedicular screw designs. The proposed loosening index calculation may be used to compare different pedicular screw designs. The proposed methodology was verified as a valuable tool to investigate the influence of the cranial-caudal loads on pedicular screw behavior. It offers a new alternative for use in pre-clinical studies on the loosening potential of pedicular screw designs.

scholarly journals 3D Printed Clamps for In Vitro Tensile Tests of Human Gracilis and the Superficial Third of Quadriceps Tendons

2021 ◽  
Vol 11 (6) ◽  
pp. 2563
Author(s):  
Ivan Grgić ◽  
Vjekoslav Wertheimer ◽  
Mirko Karakašić ◽  
Željko Ivandić
Keyword(s):  
3D Printing ◽  
Fused Deposition Modeling ◽  
Tensile Tests ◽  
Biomechanical Properties ◽  
Testing Procedure ◽  
Laboratory Equipment ◽  
Fused Deposition ◽  
Custom Made ◽  
3D Printed

Recent soft tissue studies have reported issues that occur during experimentation, such as the tissue slipping and rupturing during tensile loads, the lack of standard testing procedure and equipment, the necessity for existing laboratory equipment adaptation, etc. To overcome such issues and fulfil the need for the determination of the biomechanical properties of the human gracilis and the superficial third of the quadriceps tendons, 3D printed clamps with metric thread profile-based geometry were developed. The clamps’ geometry consists of a truncated pyramid pattern, which prevents the tendons from slipping and rupturing. The use of the thread application in the design of the clamp could be used in standard clamping development procedures, unlike in previously custom-made clamps. Fused deposition modeling (FDM) was used as a 3D printing technique, together with polylactic acid (PLA), which was used as a material for clamp printing. The design was confirmed and the experiments were conducted by using porcine and human tendons. The findings justify the usage of 3D printing technology for parts manufacturing in the case of tissue testing and establish independence from the existing machine clamp system, since it was possible to print clamps for each prepared specimen and thus reduce the time for experiment setup.

scholarly journals A region-based multiple testing method for hypotheses ordered in space or time

2015 ◽  
Vol 14 (1) ◽  
pp. 1-19 ◽  
Author(s):  
Rosa J. Meijer ◽  
Thijmen J.P. Krebs ◽  
Jelle J. Goeman
Keyword(s):  
Error Rate ◽  
Null Hypothesis ◽  
Multiple Testing ◽  
Testing Procedure ◽  
Familywise Error Rate ◽  
Expected Number ◽  
Multiple Testing Procedure ◽  
Exact Location ◽  
Testing Method

AbstractWe present a multiple testing method for hypotheses that are ordered in space or time. Given such hypotheses, the elementary hypotheses as well as regions of consecutive hypotheses are of interest. These region hypotheses not only have intrinsic meaning but testing them also has the advantage that (potentially small) signals across a region are combined in one test. Because the expected number and length of potentially interesting regions are usually not available beforehand, we propose a method that tests all possible region hypotheses as well as all individual hypotheses in a single multiple testing procedure that controls the familywise error rate. We start at testing the global null-hypothesis and when this hypothesis can be rejected we continue with further specifying the exact location/locations of the effect present. The method is implemented in the

Circumferential, not longitudinal, colonic stretch increases synaptic input to mouse prevertebral ganglion neurons

2003 ◽  
Vol 285 (6) ◽  
pp. G1129-G1138 ◽  
Author(s):  
Steven M. Miller ◽  
J. H. Szurszewski
Keyword(s):  
Synaptic Input ◽  
Muscle Tension ◽  
Circular Muscle ◽  
Longitudinal Axis ◽  
Muscle Layer ◽  
Intraluminal Pressure ◽  
Colon Wall ◽  
Mesenteric Ganglion ◽  
Ganglion Neurons

The relationship between longitudinal and circular muscle tension in the mouse colon and mechanosensory excitatory synaptic input to neurons in the superior mesenteric ganglion (SMG) was investigated in vitro. Electrical activity was recorded intracellularly from SMG neurons, and muscle tension was simultaneously monitored in the longitudinal, circumferential, or both axes. Colonic intraluminal pressure and volume changes were also monitored simultaneously with muscle tension changes. The results showed that the frequency of fast excitatory postsynaptic potentials (fEPSPs) in SMG neurons increased when colonic muscle tension decreased, when the colon relaxed and refilled with fluid after contraction, and during receptive relaxation preceding spontaneous colonic contractions. In contrast, fEPSP frequency decreased when colonic muscle tension increased during spontaneous colonic contraction and emptying. Manual stretch of the colon wall to 10-15% beyond resting length in the circumferential axis of flat sheet preparations increased fEPSP frequency in SMG neurons, but stretch in the longitudinal axis to 15% beyond resting length in the same preparations did not. There was no increase in synaptic input when tubular colon segments were stretched in their long axes up to 20% beyond their resting length. The circumferential stretch-sensitive increase in the frequency of synaptic input to SMG neurons persisted when the colonic muscles were relaxed pharmacologically by nifedipine (2 μM) or nicardipine (3 μM). These results suggest that colonic mechanosensory afferent nerves projecting to the SMG function as length or stretch detectors in parallel to the circular muscle layer.

scholarly journals Tetracycline Susceptibility Testing and Resistance Genes in Isolates of Acinetobacter baumannii-Acinetobacter calcoaceticus Complex from a U.S. Military Hospital

2009 ◽  
Vol 53 (6) ◽  
pp. 2693-2695 ◽  
Author(s):  
Kevin S. Akers ◽  
Katrin Mende ◽  
Heather C. Yun ◽  
Duane R. Hospenthal ◽  
Miriam L. Beckius ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Resistance Genes ◽  
Susceptibility Testing ◽  
Tetracycline Resistance ◽  
Acinetobacter Calcoaceticus ◽  
Multidrug Resistant ◽  
Military Hospital ◽  
Tetracycline Resistance Genes ◽  
Testing Method

ABSTRACT Infections with multidrug-resistant Acinetobacter baumannii-Acinetobacter calcoaceticus complex bacteria complicate the care of U.S. military personnel and civilians worldwide. One hundred thirty-three isolates from 89 patients at our facility during 2006 and 2007 were tested by disk diffusion, Etest, and broth microdilution for susceptibility to tetracycline, doxycycline, minocycline, and tigecycline. Minocycline was the most active in vitro, with 90% of the isolates tested susceptible. Susceptibilities varied significantly with the testing method. The acquired tetracycline resistance genes tetA, tetB, and tetA(39) were present in the isolates.

scholarly journals Activity of Ceftaroline against Aerobic Gram-Positive and Gram-Negative Pathogens: Effect of Test Method Variability

2011 ◽  
Vol 2011 ◽  
pp. 1-5
Author(s):  
Diane M. Citron ◽  
Yumi A. Warren ◽  
Kerin L. Tyrrell ◽  
Ellie J. C. Goldstein
Keyword(s):  
Bactericidal Activity ◽  
Test Method ◽  
In Vitro Test ◽  
Gram Negative ◽  
Methicillin Resistant ◽  
E Coli ◽  
Minimum Inhibitory Concentrations ◽  
Test Conditions ◽  
Vitro Test

Ceftaroline is a new cephalosporin with bactericidal activity against methicillin-resistant S. aureus (MRSA) as well as gram-negative pathogens. Variations of in vitro test conditions were found to affect ceftaroline activity, with 5% NaCl inhibiting growth and/or reducing the minimum inhibitory concentrations (MICs) for E. coli, K. pneumoniae, M. catarrhalis, H. influenzae, and streptococci, while an inoculum of 106 CFU/mL raised MICs of some E. coli, K. pneumoniae, and M. catarrhalis strains.

scholarly journals Lactic Acid Bacteria (Lactobacillus bulgaricus and Streptococcus thermophillus) in Yogurt Inhibit the Growth of Escherichia coli, Salmonella typhimurium, and Shigella sp. In Vitro

2021 ◽  
Vol 31 (4) ◽  
pp. 2
Author(s):  
IDSAP Peramiarti
Keyword(s):  
Escherichia Coli ◽  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Salmonella Typhimurium ◽  
Pathogenic Bacteria ◽  
Test Method ◽  
P Value ◽  
E Coli ◽  
Significant Difference

Diarrhea is defecation with a frequency more often than usual (three times or more) a day (10 mL/kg/day) with a soft or liquid consistency, even in the form of water alone. Pathogenic bacteria, such as Escherichia coli, Salmonella typhimurium, and Shigella sp., play a role in many cases, to which antibiotics are prescribed as the first-line therapy. However, since antibiotic resistance cases are often found, preventive therapies are needed, such as consuming yogurt, which is produced through a fermentation process by lactic acid bacteria (LAB). This research aimed to determine the activity of lactic acid bacteria (Liactobacillus bulgaricus and Streptococcus thermophilus) in yogurt in inhibiting the growth of the pathogenic bacteria E. coli, S. typhimurium, and Shigella sp. The research applied in vitro with the liquid dilution test method and the true experimental design research method with post-test-only and control group design. The design was used to see the inhibitory effect of yogurt LAB on the growth of E. coli, S. typhimurium, and Shigell sp. to compare the effect of several different yogurt concentrations, namely 20%, 40%, 60%, and 80%. The results of the Least Significance Different analysis showed that there was a significant difference between yogurt with a concentration of 0% and that with various concentrations in inhibiting the growth of E. coli, S. typhimurium, and Shigella sp. with a p-value of &lt;0.05. Whereas, there was no significant difference in the various concentrations of yogurt in inhibiting the growth of the three kinds of bacteria with a p-value of &gt; 0.05.<p class="Default" align="center"> </p>

scholarly journals Prednisolone Loaded Tamarind Gum Microspheres for Colonic Delivery

2021 ◽  
pp. 324-332
Author(s):  
Harish K. Kunjwani ◽  
Dinesh M. Sakarkar
Keyword(s):  
Drug Release ◽  
Controlled Drug Release ◽  
Local Concentration ◽  
Colonic Delivery ◽  
Simulated Environment ◽  
S 100 ◽  
Long Time ◽  
Sensitive Property ◽  
Microsphere Preparation

The aim of this work was to formulate a novel multiparticulate system having pH sensitive property and specific enzyme biodegradability for colon specific drug delivery of Prednisolone (PD). Natural polysaccharide, Tamarind gum is used for microsphere preparation and Eudratit S- 100 for coating to provide pH controlled drug release. The formulation aims at minimal degradation and optimum delivery of the drug with relatively higher local concentration, which may provide more effective therapy for inflammatory bowel disease including Crohn disease and ulcerative colitis. Tamarind gum microspheres were prepared by emulsion dehydration technique using polymer in ratio of 1:1 to 1: 9. These microspheres were coated with Eudragit S-100 by oil in oil solvent evaporation method using core: coat ration (5:1). Tamarind gum microspheres and Eudragit coated tamarind gum microspheres were evaluated for surface morphology, particle size and size distribution, percentage drug entrapment, surface accumulation studies, in vitro drug release in simulated gastrointestinal fluids. The effect of various formulation variables were studied the prepared microspheres were spherical in shape in the size range of 64 µm to 113 µm, the encapsulation efficiency was in range of 30-72% depending upon the concentration of gum. The drug release was about 14-20% in first four hours of study gradually rises in 5th hour and 85% drug release occurs in 10-12% hr thus showing desirable drug release in the colonic simulated environment. PD tamarind gum microspheres are thought to have the potential to maintain drug concentration within target ranges for a long time, decreasing the side effects caused by concentration fluctuation, ensuring the efficiency of treatment and improving patient compliance by reducing dosing frequency. The animal study done using acetic acid induced colitis model on rats also suggest the anti inflammatory activity of the formulation.

scholarly journals Skrining Mekanisme Kerja Daun Malaka (Phyllanthus emblica L.) Sebagai Antidiabetes

2018 ◽  
Vol 1 (3) ◽  
pp. 106-110
Author(s):  
Novi Irwan Fauzi ◽  
Seno Aulia Ardiansyah ◽  
Saeful Hidayat
Keyword(s):  
Mechanism Of Action ◽  
Inhibitory Activity ◽  
Leaf Extract ◽  
Test Method ◽  
Diabetic Rat ◽  
Phyllanthus Emblica ◽  
Insulin Sensitizer ◽  
Water Fraction

Daun malaka (Phyllanthus emblica L.) mempunyai potensi digunakan sebagai alternatif obat antidiabetes. Daun malaka menunjukkan efek hipoglikemia pada tikus yang diinduksi aloksan. Namun, mekanisme kerjanya belum diketahui pasti. Penelitian ini dilakukan dalam rangka skrining mekanisme kerja daun malaka sebagai antidiabetes. Skrining mekanisme kerja dilakukan terhadap fraksi air daun malaka melalui uji aktivitas inhibisi enzim α-glukosidase serta α-amilase secara in vitro dan pengujian aktivitas insulin-sensitizer terhadap ekstrak daun malaka dengan metode tes toleransi insulin secara in vivo. Fraksi air daun malaka menunjukkan aktivitas inhibisi terhadap enzim α-glukosidase serta α-amilase dengan nilai IC50 (Inhibitor Concentration 50) pada kedua enzim tersebut berturut-turut adalah 0,87% dan 8,64% b/v. Pada uji aktivitas insulin sensitizer, pemberian ekstrak daun malaka dapat meningkatkan sensitivitas insulin pada tikus diabet dengan kondisi resistensi insulin. Nilai KTTI pada kelompok tikus diabet yang diberi ekstrak daun malaka dosis 100 dan 500 mg/kgbb tikus (74,89 dan 75,57) lebih tinggi dibandingkan kelompok tikus diabet (38,41) dan kadar glukosa darah yang lebih rendah selama interval waktu pengukuran. Daun malaka telah diketahui mampu meningkatkan sekresi insulin dan pada penelitian ini menunjukkan aktivitas inhibisi enzim α-glukosidase serta α-amilase secara in vitro dan menunjukkan aktivitas insulinsensitizer pada tikus diabet dengan kondisi resistensi insulin.   Malaka leaf (Phyllanthus emblica L.) has the potential to be used as an alternative antidiabetic drug. Malacca leaves showed hypoglycemia effect in rat induced by alloxan. However, the mechanism of action is not yet known. This study was conducted to evaluate the mechanism of action of Malaka leaves as antidiabetic. Screening of the mechanism of action was carried out on the water fraction of Malaka leaf  byinhibitory activity examination  on α-glucosidase and α-amylase by in vitro studyand Evaluation of insulin-sensitizer activity of Maaka leaf leaf extract was conducted by invivo  insulin tolerance test method. Malaka leaf water fraction showed inhibitory activity against the α-glucosidase and α-amylase with IC50 values ​​(Inhibitory Concentration 50)  of0.87% and 8.64% b / v on both enzyme, respectively. The evaluation of insulin sensitizer revelead that administration ofMalaka  leaf extract can increase insulin sensitivity in diabetic rat with insulin resistance.KTTI values ​​in diabetic rats given malaka extract  at the dose of 100 and 500 mg / kg BW (74.89 and 75.57) were higher than diabetics rat (38.41) and the extract also decrease blood glucose levels during measurement time intervals . Malaka leafhas been known to increase insulin secretion and the study showedthe  inhibitory activity on α-glucosidase and α-amylase by in vitro study and showed insulinsensitizer activity in diabetic rat with insulin resistance.

The importance of aerodynamics for prosthetic limb design used by competitive cyclists with an amputation: An introduction

2014 ◽  
Vol 39 (3) ◽  
pp. 232-237 ◽  
Author(s):  
Bryce Dyer
Keyword(s):  
Field Test ◽  
Aerodynamic Drag ◽  
Field Tests ◽  
Field Testing ◽  
Test Method ◽  
Limb Amputation ◽  
Small Scale ◽  
Prosthetic Limb ◽  
Testing Method ◽  
Competitive Cyclists

Background/Objectives: This study introduces the importance of the aerodynamics to prosthetic limb design for athletes with either a lower-limb or upper-limb amputation. Study design: The study comprises two elements: 1) An initial experiment investigating the stability of outdoor velodrome-based field tests, and 2) An experiment evaluating the application of outdoor velodrome aerodynamic field tests to detect small-scale changes in aerodynamic drag respective of prosthetic limb componentry changes. Methods: An outdoor field-testing method is used to detect small and repeatable changes in the aerodynamic drag of an able-bodied cyclist. These changes were made at levels typical of alterations in prosthetic componentry. The field-based test method of assessment is used at a smaller level of resolution than previously reported. Results: With a carefully applied protocol, the field test method proved to be statistically stable. The results of the field test experiments demonstrate a noticeable change in overall athlete performance. Aerodynamic refinement of artificial limbs is worthwhile for athletes looking to maximise their competitive performance. Conclusion: A field-testing method illustrates the importance of the aerodynamic optimisation of prosthetic limb components. The field-testing protocol undertaken in this study gives an accessible and affordable means of doing so by prosthetists and sports engineers. Clinical relevance Using simple and accessible field-testing methods, this exploratory experiment demonstrates how small changes to riders’ equipment, consummate of the scale of a small change in prosthetics componentry, can affect the performance of an athlete. Prosthetists should consider such opportunities for performance enhancement when possible.

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