Publications by authors named "Dinesh Kalyanasundaram"

22 Publications

  • Page 1 of 1

Estimation of forces on anterior cruciate ligament in dynamic activities.

Biomech Model Mechanobiol 2021 Apr 20. Epub 2021 Apr 20.

Centre for Biomedical Engineering, Indian Institute of Technology Delhi, New Delhi, 110016, India.

In this work, a nonlinear strain rate dependent plugin developed for the OpenSim® platform was used to estimate the instantaneous strain rate (ISR) and the forces on the ACL's anteromedial (aACL) and posterolateral (pACL) bundles during walking and sudden change of direction of running termed as 'plant-and-cut' (PC). The authors obtained the kinematics data for walking via optical motion capture. PC movements, along with running kinematics, were obtained from the literature. A nonlinear plugin developed for ligaments was interfaced with OpenSim® platform to simulate walking and PC motions with a flexed knee and an extended knee. PC phase is sandwiched between an approach phase and take-off phase and was studied at various event velocities (1.8, 3, and 4.2 m s), and angles of PC (23°, 34°, and 45°) as encountered in adult ball games. In both cases of PC-with-extended knee and PC-with-flexed-knee, the maximum forces on both the ACL bundles were observed after the take-off phase. A maximum force of ~ 35 N kg of body weight (BW) was observed on aACL after the take-off phase for an event velocity of 4.2 m s. In the posterolateral bundle (pACL), the maximum forces (~ 40 N kg of BW) were observed towards the end of the mid-swing phase (after the take-off phase) for the various combinations of the parameters studied. The forces observed in the simulation of PC-with-flexed-knee and PC-with-extended-knee has resulted in magnitude higher than sustainable by the adults. This study is novel in attempting to incorporate differing rates-of-strain that have been shown to alter soft tissue properties into the OpenSim® musculoskeletal model. The proposed model can be used by researchers to predict the forces during various kinematic activities for other soft tissues.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s10237-021-01461-5DOI Listing
April 2021

Epoxy based sandwich composite using three-dimensional integrally woven fabric as core strengthened with additional carbon face-sheets.

J Mech Behav Biomed Mater 2021 04 13;116:104317. Epub 2021 Jan 13.

Centre for Biomedical Engineering, Indian Institute of Technology, New Delhi, 110016, India; Department of Biomedical Engineering, All India Institute of Medical Sciences, New Delhi, 110029, India. Electronic address:

Sandwich composites are three-dimensional (3D) composite structures that offer higher stiffness with overall low density. However, they suffer from low strength; thus, not suited for load bearing applications. In this work, an attempt is made to develop a high strength lightweight sandwich composite suited for load-bearing applications. A sandwich composite based on 3D integrally woven fabric with thickness 3 mm as the core and strengthened with additional 2x2 twill woven carbon fabric face-sheets is reported. The samples were manufactured by wet hand lay co-lamination process using Araldite® LY 1564 epoxy as the matrix polymer and with fiber fraction of 50% by weight. The number of additional carbon face-sheets over the core was varied from two to eight in steps of two. The composite samples were experimented under three-point bending and edgewise compression tests to determine the flexural and compressive strengths in both warp and weft directions. The weft direction samples yielded higher flexural and compressive strengths due to the continuous arrangement of the core pile yarn. The samples with six carbon face-sheets tested along the weft direction offered the highest specific strengths of ~409 kN m/kg and 259 kN m/kg in bending and compression tests. Similarly, the flexural strength was ~340 MPa, and compressive strength was ~217 MPa. A detailed fractography study revealed no core crushing or compression failure of the core during bending tests.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jmbbm.2021.104317DOI Listing
April 2021

Levels of TGF-β1 in peri-miniscrew implant crevicular fluid.

J Oral Biol Craniofac Res 2020 Apr-Jun;10(2):93-98. Epub 2020 Mar 6.

Centre for Biomedical Engineering, Indian Institute of Technology Delhi, New Delhi, 110016, India.

The peri-miniscrew implant crevicular fluid is analogous to gingival crevicular fluid, and its contents reflect the state of inflammation and health during the life of the miniscrews in the mouth. The stability of MSI is fundamental to its role as an anchorage. This study aimed to evaluate transforming growth factor-beta one (TGF-β1) of the peri-miniscrew implant crevicular fluid (PMICF), on implant insertion, pre- and post-loading of MSIs to find a clue to their role in the stability of MSI. Fifty-two MSIs sites were placed in the mouths of 13 patients aged 12-26 years undergoing orthodontic treatment. PMICF was collected using micro-pipettes at T1 (day 0, 1 h after MSI implantation), T2 (day 1), T3/baseline (day 21, preloading of MSI), T4 (day 21, 1 h post loading), T5 (day 22, 1 day post loading), T6 (day 43, 3 weeks post loading). The levels of TGF-β1 were estimated by enzyme-linked immunosorbent assay (ELISA). The data were subjected to statistical analysis. Of the 52 MSIs, 20 MSIs failed at T3. In the case of successful MSIs, the TGF-β1 levels were found to monotonously decrease from T1 (~1400 pg/mL) until T3 (~700 pg/mL) and saturate thereafter. In the case of failed MSIs, the levels of TGF-β1 at various time periods were approximately constant and of much lower value than corresponding time periods of successful MSIs. This study highlights the role of TGF- β1 in bone metabolism around miniscrew reflecting the state of inflammation from 1 h post-implantation.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jobcr.2020.03.002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7082543PMC
March 2020

Simultaneous and high sensitive detection of Salmonella typhi and Salmonella paratyphi a in human clinical blood samples using an affordable and portable device.

Biomed Microdevices 2019 11 9;21(4):95. Epub 2019 Nov 9.

Centre for Biomedical Engineering, Indian Institute of Technology Delhi, New Delhi, 110016, India.

Enteric fever is one of the leading causes of infection and subsequent fatality (greater than 1.8 million) (WHO 2018), especially in the developing countries due to contaminated water and food inter twinned with unhygienic practices. Clinical gold standard technique of culture-based method followed by biochemical tests demand 72+ hours for diagnosis while newly developed techniques (like PCR, RT-PCR, DNA microarray etc.) suffer from high limit of detection or involve high-cost infrastructure or both. In this work, a quick and highly specific method, SMOL was established for simultaneous detection of Salmonella paratyphi A and Salmonella typhi in clinical blood samples. SMOL consists of (i) pre-concentration of S. typhi and S. paratyphi A cells using magnetic nanoparticles followed by (ii) cell lysis and DNA extraction (iii) amplification of select nucleic acids by LAMP technique and (iv) detection of amplified nucleic acids using an affordable portable device (costs less than $70). To identify the viability of target cells at lower concentrations, the samples were processed at two different time periods of t = 0 and t = 4 h. Primers specific for the SPA2539 gene in S. paratyphi A and STY2879 gene in S. typhi were used for LAMP. Within 6 h SMOL was able to detect positive and negative samples from 55 human clinical blood culture samples and detect the viability of the cells. The results were concordant with culture and biochemical tests as well as by qPCR. Statistical power analysis yielded 100%. SMOL results were concordant with culture and biochemical tests as well as by qPCR. The sensitive and affordable system SMOL will be effective for poor resource settings.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s10544-019-0441-6DOI Listing
November 2019

Graphene Quantum Dots in the Game of Directing Polymer Self-Assembly to Exotic Kagome Lattice and Janus Nanostructures.

ACS Nano 2019 Aug 7;13(8):9397-9407. Epub 2019 Aug 7.

Amity Institute of Biotechnology , Amity University , Noida 201303 , India.

Graphene quantum dots (GQDs) are the harbingers of a paradigm shift that revitalize self-assembly of the colloidal puzzle by adding shape and size to the material-design palette. Although self-assembly is ubiquitous in nature, the extent to which these molecular legos can be engineered reminds us that we are still apprenticing polymer carpenters. In this quest to unlock exotic nanostructures ascending from eventual anisotropy, we have utilized different concentrations of GQDs as a filler in free-radical-mediated aqueous copolymerization. Extensive polymer grafting over the geometrically confined landscape of GQDs (0.05%) bolsters crystallization instilling a loom which steers interaction of polymeric cilia into interlaced equilateral triangles with high sophistication. Such two-dimensional (2D) assemblies epitomizing the planar tiling of "Star of David" forming a molecular kagome lattice (KL) without metal templation evoke petrichor. Interestingly, a higher percentage (0.3%) of GQDs allow selective tuning of the interfacial property of copolymers breaking symmetry due to surface energy incongruity, producing exotic Janus nanomicelles (JNMs). Herein, with the help of a suite of characterizations, we delineate the mechanism behind the formation of the KL and JNMs which forms a depot of heightened drug accretion with targeted delivery of 5-fluorouracil in the colon as validated by gamma scintigraphy studies.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acsnano.9b04188DOI Listing
August 2019

An open-source plugin for OpenSim to model the non-linear behaviour of dense connective tissues of the human knee at variable strain rates.

Comput Biol Med 2019 07 31;110:186-195. Epub 2019 May 31.

Centre for Biomedical Engineering, Indian Institute of Technology Delhi, New Delhi, 110016, India; Department of Biomedical Engineering, All India Institute of Medical Sciences, New Delhi, 110029, India. Electronic address:

The force-length characteristics of dense connective tissues (DCTs) vary non-linearly as a function of strain rate. However, there is no class of OpenSim available to incorporate the effect of strain rate into the OpenSim model. In this work, a new plugin for OpenSim was developed to incorporate the non-linear strain rate behaviour of dense connective tissues (DCTs) of the human knee. Experimental force-length plots from the literature were used to extract the shape factor, scale factor, the coefficient of viscosity and elastic stiffness corresponding to specific strain rates. A new class object termed as NonLinearLigament was formulated using a customized plugin based on a structural constitutive model. A test platform was created to evaluate the force-length patterns at multiple strain rates ranging from 0.0001 s to 100 s for the DCT bundles. Knee kinematics of 25 DCT bundles were subjected to forward simulation at various strain rates. To understand the significance, the force-length characteristics of each of the DCTs were simulated as a function of strain rate for both existing Ligament class of OpenSim and the proposed NonLinearLigament class. In the proposed ligament class, higher forces were observed with an increase of strain rate in DCTs. Existing Ligament class in OpenSim was devoid of any changes at different strain rates. In summary, the developed plugin takes into account the short term viscoelastic behaviour of DCTs and hence, would help in accurate modelling of tissue behaviour specifically for dynamic situations.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.compbiomed.2019.05.021DOI Listing
July 2019

Relationship between Dislocation Density and Antibacterial Activity of Cryo-Rolled and Cold-Rolled Copper.

Materials (Basel) 2019 Jan 9;12(2). Epub 2019 Jan 9.

Centre for Biomedical Engineering, Indian Institute of Technology Delhi, New Delhi 110016, India.

In the present work, cold rolling and cryo-rolling were performed on 99% commercially pure copper substrates. Both cold and cryo-rolling processes caused severe plastic deformation that led to an increase in dislocation density by 14× and 28× respectively, as compared to the pristine material. Increases in average tensile strengths, by 75% (488 MPa) and 150% (698 MPa), were observed in the two rolled materials as the result of the enhancement in dislocation density. In addition to strength, enhanced antibacterial property of cryo-rolled copper was observed in comparison to cold rolled and pristine copper. Initial adhesion and subsequent proliferation of bio-film forming Gram-positive bacteria was reduced by 66% and 100% respectively for cryo-rolled copper. Approximately 55% protein leakage, as well as ethidium bromide (EtBr) uptake, were observed confirming rupture of cell membrane of Inductively coupled plasma-mass spectroscopy reveals higher leaching of elemental copper in nutrient broth media from the cryo-rolled copper. Detailed investigations showed that increased dislocation led to leaching of copper ions that caused damage to the bacterial cell wall and consequently killing of bacterial cells. Cryo-rolling enhanced both strength, as well as antibacterial activity, due to the presence of dislocations.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/ma12020200DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6356488PMC
January 2019

Effect of preservation methods on tensile properties of human femur-ACL-tibial complex (FATC) - a cadaveric study on male subjects.

Acta Bioeng Biomech 2018 ;20(4):31-42

Centre for Biomedical Engineering, Indian Institute of Technology (IIT) Delhi, New Delhi, India.

Purpose: Deep freezing and storing in formalin are some of the common techniques of human tissue preservation. However, the preservation modes affect the biomechanical properties of the tissues. In this work, the effects of the above-stated preservation tech- niques are compared with that of fresh cadaveric samples.

Methods: FATC samples from male cadavers of age between 60 and 70 years were tested under tensile loading at a strain rate of 0.8 s-1. Fourteen FATC samples from soft embalmed cadavers were preserved for 3 weeks by two methods: (a) 10% formalin and (b) deep freezing at -20 ° C followed by thawing. Seven FATC samples from fresh ca- davers were experimented as control samples. The results were evaluated by a two-stage statistical process of Kruskal-Wallis H test and Mann-Whitney U-test.

Results: It was observed that the failure force of fresh cadavers was the highest while that of preserved samples were approximately half the value. Failure elongation of frozen samples exceeded fresh samples while formalin samples failed at lesser elongations. Higher incidence of tibial insertion point or mid-section failures were observed in fresh samples while the higher incidence of ruptures at femoral insertion point was observed in the two preservation methods.

Conclusion: Tensile properties of fresh tissues vary significantly from that of formalin preserved or frozen preserved samples.
View Article and Find Full Text PDF

Download full-text PDF

Source
March 2019

Experimental assessment of biomechanical properties in human male elbow bone subjected to bending and compression loads.

J Appl Biomater Funct Mater 2019 Apr-Jun;17(2):2280800018793816. Epub 2018 Sep 19.

1 Centre for Biomedical Engineering, Indian Institute of Technology (IIT) Delhi, New Delhi, India.

This work discusses the biomechanical testing of 3 elbow bones, namely the humerus, ulna, and radius. There is a need to identify the mechanical properties of the bones at the organ level. The following tests were performed: 3-point bending, fracture toughness, and axial compression. Six sets of whole-bone samples of human male cadaveric humerus, ulna, and radius (age of donor: 35 to 56 years) were tested. The results were analyzed for statistical significance by 2-stage, repeated-measure analysis of variance (ANOVA). The difference between the bending strength of the humerus, ulna, and radius was statistically significant ( P = .001) when compared to one another. However, the fracture toughness and compressive strength were observed to be similar for the 3 bones. The knowledge of mechanical properties of elbow bones can aid in the design of elbow implants and upper limb protection systems, and also allow us to identify criteria for injury. Further, knowledge of the mechanical properties of the elbow bones can aid in calibrating simulations through finite elements analysis.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1177/2280800018793816DOI Listing
December 2019

Rapid Detection Device for in Milk, Juice, Water and Calf Serum.

Indian J Microbiol 2018 Sep 30;58(3):381-392. Epub 2018 Apr 30.

1Device Testing Laboratory, Centre for Biomedical Engineering, Indian Institute of Technology Delhi, New Delhi, 110016 India.

A limit of detection of 200 CFU/mL of spiked in various sample matrices were achieved in 30 min. The sample matrices were raw/unprocessed milk, commercially available milk, juice from packed bottles, fresh juice from carts, potable water, turbid water and calf serum. The complete protocol comprised of three steps: (a) cell lysis (b) nucleic acid amplification and (c) an in situ optical detection. The cell lysis was carried out using a simple heating based protocol, while the loop-mediated isothermal amplification of DNA was carried out by an in-house designed and fabricated system. The developed system consists of an aluminum block fitted with two cartridge heaters along with a thermocouple. The system was coupled to a light source and spectrometer for a simultaneous in situ detection. Primers specific for STY2879 gene were used to amplify the nucleic acid sequence, isolated from cells. The protocol involves 15 min of cell lysis and DNA isolation followed by 15 min for isothermal amplification and simultaneous detection. No cross-reactivity of the primers were observed at 10 CFU/mL of , , , , . In addition, the system was able to detect of 200 CFU/mL in a concoction of 10 CFU/mL of , 10 CFU/mL of , and 10 CFU/mL of hepatocyte-derived cellular carcinoma HUH7 cells. The proposed rapid diagnostic system shows a promising future in the field of food and medical diagnostics.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s12088-018-0730-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6023822PMC
September 2018

A Review on Biomechanics of Anterior Cruciate Ligament and Materials for Reconstruction.

Appl Bionics Biomech 2018 13;2018:4657824. Epub 2018 May 13.

Centre for Biomedical Engineering, Indian Institute of Technology Delhi, New Delhi, India.

The anterior cruciate ligament is one of the six ligaments in the human knee joint that provides stability during articulations. It is relatively prone to acute and chronic injuries as compared to other ligaments. Repair and self-healing of an injured anterior cruciate ligament are time-consuming processes. For personnel resuming an active sports life, surgical repair or replacement is essential. Untreated anterior cruciate ligament tear results frequently in osteoarthritis. Therefore, understanding of the biomechanics of injury and properties of the native ligament is crucial. An abridged summary of the prominent literature with a focus on key topics on kinematics and kinetics of the knee joint and various loads acting on the anterior cruciate ligament as a function of flexion angle is presented here with an emphasis on the gaps. Briefly, we also review mechanical characterization composition and anatomy of the anterior cruciate ligament as well as graft materials used for replacement/reconstruction surgeries. The key conclusions of this review are as follows: (a) the highest shear forces on the anterior cruciate ligament occur during hyperextension/low flexion angles of the knee joint; (b) the characterization of the anterior cruciate ligament at variable strain rates is critical to model a viscoelastic behavior; however, studies on human anterior cruciate ligament on variable strain rates are yet to be reported; (c) a significant disparity on maximum stress/strain pattern of the anterior cruciate ligament was observed in the earlier works; (d) nearly all synthetic grafts have been recalled from the market; and (e) bridge-enhanced repair developed by Murray is a promising technique for anterior cruciate ligament reconstruction, currently in clinical trials. It is important to note that full extension of the knee is not feasible in the case of most animals and hence the loading pattern of human ACL is different from animal models. Many of the published reviews on the ACL focus largely on animal ACL than human ACL. Further, this review article summarizes the issues with autografts and synthetic grafts used so far. Autografts (patellar tendon and hamstring tendon) remains the gold standard as nearly all synthetic grafts introduced for clinical use have been withdrawn from the market. The mechanical strength during the ligamentization of autografts is also highlighted in this work.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1155/2018/4657824DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5971278PMC
May 2018

Outcome and safety analysis of 3D-printed patient-specific pedicle screw jigs for complex spinal deformities: a comparative study.

Spine J 2019 01 3;19(1):56-64. Epub 2018 May 3.

Centre for Biomedical Engineering, Block-III, Room No. 398, Indian Institute of Technology, New Delhi-110016, India.

Background Context: Spinal deformities are very challenging to treat and have a great risk of neurologic complications because of hardware placement during corrective surgery. Various techniques have been introduced to ensure safe and accurate placement of pedicle screws. Patient-specific screw guides with predrawn and prevalidated trajectory seem to be an attractive option.

Purpose: We have focused on developing three-dimensional (3D) printing technique for complex spinal deformities in India. This study also aimed to compare the placement of pedicle screw with 3D printing and freehand technique.

Study Design/settings: This is a retrospective comparative clinical study in an academic institutional setting.

Patient Sample: A total of 20 patients were enrolled during the study: 10 were operated on with the help of 3D printing (Group 1) and 10 were operated on with freehand technique (Group 2). Group 1 included six patients with congenital scoliosis, three patients with adolescent idiopathic scoliosis (AIS), and one patient with post-tubercular kyphosis, and Group 2 included five patients with congenital scoliosis, four patients with AIS, and one patient with post-tubercular kyphosis.

Outcome Measures: Primary outcomes were measured in terms of screw violation, and secondary outcomes were measured in terms of surgical time, blood loss, radiation exposure (number of shoots required), and complications.

Materials And Methods: MIMICS Base v18.0 software was used for 3D reconstruction from computed tomography scan images of all the patients. 3-Matic software was used to create a drill guide. A 3D printer from Stratasys Mojo with ABS P430 model material cartilage (a thermoplastic material) was used for the printing of the vertebra model and jigs. A two-sample test of proportion was used to compare correctly and wrongly placed pedicle screws with 3D printing and freehand technique. t Test with equal variance was used for operating surgical time and blood loss.

Results: No superior or inferior screw violation was observed in any of our patients in either group. We found a significant difference (p=.03) between the two groups regarding perfect screw placement in favor of 3D printing. There were 13 Grade 2 medial perforations in the freehand group and 3 in the 3D printing group. There was no Grade 3 medial perforation in either group. Six Grade 2 lateral perforations in the freehand group and seven in the 3D printing group were observed. Three Grade 3 lateral perforations in the freehand group and two in 3D printing group were observed. Analysis showed a statistically significant (p=.005) medial violation in the freehand group. Surgical time was significantly less (p=.03) in the 3D printing group compared with the freehand group. Mean blood loss was higher in the freehand group but was not statistically significant (p=.3) in the 3D printing group. Fluoroscopic shots required were less in number in the 3D printing group compared with the freehand group. There was no neurologic deficit in any of the patients in the two groups.

Conclusions: In our study, focusing on spinal deformities with statistically significant higher rates of accurate screw positioning and higher numbers of inserted screws with 3D printing was possible because of enhanced safety, particularly at apical levels. As such, spinal deformities are difficult to treat worldwide. In India, these deformities are often neglected and present at a very late and a much more deformed state when their treatment becomes even more challenging. Developing these patient-specific drill templates will enable an average spine surgeon to treat these patients with much ease and safety.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.spinee.2018.05.001DOI Listing
January 2019

An extended OpenSim knee model for analysis of strains of connective tissues.

Biomed Eng Online 2018 Apr 17;17(1):42. Epub 2018 Apr 17.

Centre for Biomedical Engineering, Indian Institute of Technology Delhi, New Delhi, 110016, India.

Background: OpenSim musculoskeletal models provide an accurate simulation environment that eases limitations of in vivo and in vitro studies. In this work, a biomechanical knee model was formulated with femoral articular cartilages and menisci along with 25 connective tissue bundles representing ligaments and capsules. The strain patterns of the connective tissues in the presence of femoral articular cartilage and menisci in the OpenSim knee model was probed in a first of its kind study.

Methods: The effect of knee flexion (0°-120°), knee rotation (- 40° to 30°) and knee adduction (- 15° to 15°) on the anterior cruciate, posterior cruciate, medial collateral, lateral collateral ligaments and other connective tissues were studied by passive simulation. Further, a new parameter for assessment of strain namely, the differential inter-bundle strain of the connective tissues were analyzed to provide new insights for injury kinematics.

Results: ACL, PCL, LCL and PL was observed to follow a parabolic strain pattern during flexion while MCL represented linear strain patterns. All connective tissues showed non-symmetric parabolic strain variation during rotation. During adduction, the strain variation was linear for the knee bundles except for FL, PFL and TL.

Conclusions: Strains higher than 0.1 were observed in most of the bundles during lateral rotation followed by abduction, medial rotation and adduction. In the case of flexion, highest strains were observed in aACL and aPCL. A combination of strains at a flexion of 0° with medial rotation of 30° or a flexion of 80° with rotation of 30° are evaluated as rupture-prone kinematics.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1186/s12938-018-0474-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5905155PMC
April 2018

Volumetric locking free 3D finite element for modelling of anisotropic visco-hyperelastic behaviour of anterior cruciate ligament.

J Biomech 2018 05 16;73:1-8. Epub 2018 Mar 16.

Centre for Biomedical Engineering, Indian Institute of Technology Delhi, New Delhi 110016, India; Department of Biomedical Engineering, All India Institute of Medical Sciences, New Delhi 110029, India.

Solids such as polymers, soft biological tissues display visco-hyperelastic, isochoric and finite deformation behaviour. The incompressibility constraint imposed severe restriction on the displacement field results in volumetric locking. Many techniques have been developed to address the issue such as reduced integration, mixed formulation, B-Bar and F-Bar methods, each of them with their own merits and demerits. In this work, we have developed a 3D finite element (hereby referred as J-Bar method) to counter volumetric locking in visco-hyperelastic solids. To validate the proposed J-Bar method, rheological characteristics of the human anterior cruciate ligament (ACL) were predicted and compared with the experimental results.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jbiomech.2018.03.016DOI Listing
May 2018

Highly-sensitive detection of Salmonella typhi in clinical blood samples by magnetic nanoparticle-based enrichment and in-situ measurement of isothermal amplification of nucleic acids.

PLoS One 2018 28;13(3):e0194817. Epub 2018 Mar 28.

Centre for Biomedical Engineering, Indian Institute of Technology Delhi, New Delhi, India.

Enteric fever continues to be a major cause of mortality and morbidity globally, particularly in poor resource settings. Lack of rapid diagnostic assays is a major driving factor for the empirical treatment of enteric fever. In this work, a rapid and sensitive method 'Miod' 'has been developed. Miod includes a magnetic nanoparticle-based enrichment of target bacterial cells, followed by cell lysis and loop-mediated isothermal amplification (LAMP) of nucleic acids for signal augmentation along with concurrent measurement of signal via an in-situ optical detection system. To identify positive/negative enteric fever infections in clinical blood samples, the samples were processed using Miod at time = 0 hours and time = 4 hours post-incubation in blood culture media. Primers specific for the STY2879 gene were used to amplify the nucleic acids isolated from S. typhi cells. A limit of detection of 5 CFU/mL was achieved. No cross-reactivity of the primers were observed against 106 CFU/mL of common pathogenic bacterial species found in blood such as E. coli, P. aeruginosa, S. aureus, A. baumanni, E. faecalis, S. Paratyphi A and K. pneumonia. Miod was tested on 28 human clinical blood samples. The detection of both pre-and post-four-hours incubation confirmed the presence of viable S. typhi cells and allowed clinical correlation of infection. The positive and negative samples were successfully detected in less than 6 hours with 100% sensitivity and specificity.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0194817PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5874042PMC
July 2018

An Affordable Insole-Sensor-Based Trans-Femoral Prosthesis for Normal Gait.

Sensors (Basel) 2018 Feb 27;18(3). Epub 2018 Feb 27.

Centre for Biomedical Engineering, Indian Institute of Technology Delhi, New Delhi 110016, India.

This paper proposes a novel and an affordable lower limb prosthesis to enable normal gait kinematics for trans-femoral amputees. The paper details the design of a passive prosthesis with magneto-rheological (MR) damping system and electronic control. A new control approach based on plantar insole feedback was employed here. Strategically placed sensors on the plantar insole provide required information about gait cycle to a finite state controller for suitable action. A proportional integral (PI) based current controller controls the required current for necessary damping during gait. The prosthesis was designed and developed locally in India keeping in view the cost, functionality, socio-economic, and aesthetic requirements. The prototype was experimentally tested on a trans-femoral amputee and the results are presented in this work. The implementation of the proposed design and control scheme in the prototype successfully realizes the notion that normal gait kinematics can be achieved at a low cost comparable to passive prostheses. The incurring cost and power expenditure of the proposed prosthesis are evaluated against passive and active prostheses, respectively. The commercial implications for the prosthesis were explored on the basis of recommendations of ISPO Consensus Conference on Appropriate Prosthetic Technology in Developing Countries. The key objective of this work is to enable lucid design for development of an affordable prosthesis in a low-resource setting.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/s18030706DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5876733PMC
February 2018

A review of biomarkers in peri-miniscrew implant crevicular fluid (PMICF).

Prog Orthod 2017 Nov 27;18(1):42. Epub 2017 Nov 27.

Centre for Biomedical Engineering, Indian Institute of Technology Delhi, New Delhi, India.

Background: The temporary anchorage devices (TADs) which include miniscrew implants (MSIs) have evolved as useful armamentarium in the management of severe malocclusions and assist in complex tooth movements. Although a multitude of factors is responsible for the primary and secondary stability of miniscrew implants, contemporary research highlights the importance of biological interface of MSI with bone and soft tissue in augmenting the success of implants. The inflammation and remodeling associated with MSI insertion or loading are reflected through biomarkers in peri-miniscrew implant crevicular fluid (PMICF) which is analogous to the gingival crevicular fluid. Analysis of biomarkers in PMICF provides indicators of inflammation at the implant site, osteoclast differentiation and activation, bone resorption activity and bone turnover. The PMICF for assessment of these biomarkers can be collected non-invasively via paper strips, periopaper or micro capillary pipettes and analysed by enzyme-linked immunosorbent assay (ELISA) or immunoassays. The markers and mediators of inflammation have been previously studied in relation to orthodontic tooth movement include interleukins (IL-1β, IL-2, IL-6 and IL-8), growth factors and other proteins like tumour necrosis factor (TNF-α), receptor activator of nuclear factor kappa-B ligand (RANKL), chondroitin sulphate (CS) and osteoprotegerin (OPG). Studies have indicated that successful and failed MSIs have different concentrations of biomarkers in PMICF. However, there is a lack of comprehensive information on this aspect of MSIs. Therefore, a detailed review was conducted on the subject.

Results: A literature search revealed six relevant studies: two on IL-1β; one on IL-2, IL-6 and IL-8; one on TNF-α; one on CS; and one on RANKL/OPG ratio. One study showed an increase in IL-1β levels upon MSI loading, peak in 24 hours (h), followed by a decrease in 21 days to reach baseline in 300 days. A 6.87% decrease in IL-2 levels was seen before loading and a 5.97% increase post-loading. IL-8 showed a 6.31% increase after loading and IL-6 increased by 3.08% before MSI loading and 15.06% after loading. RANKL/OPG ratio increased in loaded compared to unloaded MSIs.

Conclusions: Cytokines (mainly ILs and TNF-α) and RANKL/OPG ratio showed alteration in PMICF levels upon loading of MSIs as direct or indirect anchorage.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1186/s40510-017-0195-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5702602PMC
November 2017

Authors' response.

Am J Orthod Dentofacial Orthop 2015 Sep;148(3):362-3

New Delhi, India.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ajodo.2015.07.005DOI Listing
September 2015

Surface deterioration and elemental composition of retrieved orthodontic miniscrews.

Am J Orthod Dentofacial Orthop 2015 Apr;147(4 Suppl):S88-100

Assistant professor, Centre for Biomedical Engineering, Indian Institute of Technology, Delhi; assistant professor, Department of Biomedical Engineering, All India Institute of Medical Sciences, New Delhi, India.

Introduction: This study provides insight into surface and elemental analyses of orthodontic retrieved miniscrew implants (MSIs). The sole purpose was to investigate the behavior of MSIs while they are in contact with bone and soft tissues, fluids, and food in the oral cavity. The information thus gathered may help to understand the underlying process of success or failure of MSIs and can be helpful in improving their material composition and design.

Methods: The study was carried out on 28 titanium-alloy MSIs (all from the same manufacturer) split into 3 groups: 18 MSIs were retrieved after successful orthodontic treatment, 5 were failed MSIs, and 5 were as-received MSIs serving as the controls. All MSIs were subjected to energy dispersive x-ray microanalysis to investigate the changes in surface elemental composition and to scanning electron microscopy to analyze their surface topography. Data thus obtained were subjected to suitable statistical analyses.

Results: Scanning electron microscope analysis showed surface manufacturing imperfections of the as-received MSIs in the form of stripes. Their elemental composition was confirmed to the specifications of the American Society for Testing of Materials for surgical implants. Retrieved MSIs exhibited generalized surface dullness; variable corrosion; craters in the head, neck, body, and tip regions; and blunting on tips and threads. Energy dispersive x-ray analyses showed deposition of additional elements: calcium had greater significance in its proportion in the body region by 0.056 weight percent; iron was seen in greater proportion in the failed retrieved MSIs compared with the successful miniscrews; cerium was seen in greater proportions in the head region by 0.128 weight percent and in the neck region by 0.147 weight percent than in the body and tip regions of retrieved MSIs.

Conclusions: Retrieved MSIs showed considerable surface and structural alterations such as dullness, corrosion, and blunting of threads and tips. Their surfaces showed interactions and adsorption of several elements, such as calcium, at the body region. A high content of iron was found on the failed MSIs, and cerium was seen in the head and neck regions of retrieved MSIs.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ajodo.2014.10.034DOI Listing
April 2015

Nanotips for single-step preparation of DNA for qPCR analysis.

Analyst 2013 Jun;138(11):3135-8

Department of Mechanical Engineering, University of Washington, Seattle, WA, USA.

A single-step concentration and elution method is developed for detection of DNA in buffer, saliva, and blood. A nanotip capturing DNA using an electric field and capillary action is directly dissolved in buffer for qPCR analysis. The concentration yield and the relative parameters are compared with those of a commercial kit.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1039/c3an00170aDOI Listing
June 2013

Immunosensor towards low-cost, rapid diagnosis of tuberculosis.

Lab Chip 2012 Apr 6;12(8):1437-40. Epub 2012 Mar 6.

Department of Mechanical Engineering, University of Washington, Box 352600, Seattle, Washington 98195, USA.

A rapid, accurate tuberculosis diagnostic tool that is compatible with the needs of tuberculosis-endemic settings is a long-sought goal. An immunofluorescence microtip sensor is described that detects Mycobacterium tuberculosis complex cells in sputum in 25 minutes. Concentration mechanisms based on flow circulation and electric field are combined at different scales to concentrate target bacteria in 1 mL samples onto the surfaces of microscale tips. Specificity is conferred by genus-specific antibodies on the microtip surface. Immunofluorescence is then used to detect the captured cells on the microtip. The detection limit in sputum is 200 CFU mL(-1) with a success rate of 96%, which is comparable to PCR.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1039/c2lc21131aDOI Listing
April 2012