199 research outputs found
Performance Analysis of Process Parameters on Machining Titanium (Ti-6Al-4V) Alloy Using Abrasive Water Jet Machining Process
No full textAbstractOwing to its light weight and corrosive resistant, Titanium (Ti-6Al-4V) alloy is mainly utilized in fabricating medical device applications. Since it has high strength, it is very difficult to machine alloy using conventional machining. In the present study, an endeavor has been made to machine titanium alloy using AWJM process. Since the process involves with less heat affect zone and higher material removal, it is possible to enhance machinability of workpiece. It has attempted to find the influence of process parameters on surface roughness and topography for enhancing the process. It has been observed that the abrasive flow rate and standoff distance has the most significant role on determining surface quality
CryoEM structure of canonical rice nucleosome core particle
No full textPDB ID: 8Q15 DOI Citation: Sotelo-Parrilla, P., Hari Sundar G, V., Raju, S., Jha, S., Gireesh, A., Gut, F., Vinothkumar, K.R., Berger, F., Shivaprasad, P.V., Jeyaprakash, A.A., (2025) CryoEM structure of canonical rice nucleosome core particle doi: https://doi.org/10.2210/pdb8q15/pd
CryoEM structure of rice nucleosome containing a H4 variant chimera
No full textPDB ID: 8Q16 DOI Citation: Sotelo-Parrilla, P., Hari Sundar G, V., Raju, S., Jha, S., Gireesh, A., Gut, F., Vinothkumar, K.R., Berger, F., Shivaprasad, P.V., Jeyaprakash, A.A., (2025) CryoEM structure of rice nucleosome containing a H4 variant chimera doi: https://doi.org/10.2210/pdb8q16/pd
Multi Criteria Decision Making of Abrasive Flow Oriented Process Parameters in Abrasive Water Jet Machining Using Taguchi–DEAR Methodology
No full textOwing to its ability of machining higher strength materials such as titanium alloy with less heat affected zone and higher material removal rate, abrasive water jet machining process is widely used in manufacturing industries. Since the process associated with more than one performance measure, it is important to introduce the multiple response decision making for optimizing the process parameters in the process. The experimental trials have been conducted under Taguchi based L-9 orthogonal table with different levels of input process parameters such as liquid water pressure, abrasive particles flow rate, feed rate and stand-off distance. Taguchi - Data Envelopment Analysis based Ranking based multiple response decision making has been used to enhance the performance measures such as surface roughness and material removal rate in the present study. From the experimental results, the optimal process parameters have been computed among the selected input process parameters. It has also been found that standoff distance has higher influence on determining the performance measures owing to its importance on determining impact energy in the process
Strukturelle Studien von Proteinen involviert in Membrantransport
No full textMy graduate thesis is on the "Structural studies of membrane transport proteins". Transporters are membrane proteins that have multiple membrane-spanning a-helices. They are dynamic and diverse proteins, undergoing a large conformational change and transporting wide range of susbtrates. Based on their energy source they can be classified into primary and secondary transport systems. Primary transport systems are driven by the use of chemical (ATP) or light energy, while secondary transporters utilize ion gradients to transport substrates. I began my PhD dissertation on secondary transporters by two-dimensional crystallization and electron crystallographic analysis and recently my focus also has shifted towards 3D crystallization. The following projects constitute my PhD thesis: 1) 2D crystallization of MjNhaP1 and pH induced structural change: MjNhaP1, a Na+/H+ antiporter that is regulated by pH has been implicated in homeostasis of H+ and Na+ in Methanococcus jannaschii, a hyperthermophilic archaeon that grows optimally at 85°C. MjNhaP1 was cloned and expressed in E. coli. Two-dimensional crystals were obtained from purified protein at pH4. Electron cryo-microscopy yielded an 8Å projection map. The map of MjNhaP1 shows elongated densities in the centre of the dimer and a cluster of density peaks on either side of the dimer core, indicative of a bundle of 4-6 membrane-spanning helices. The effect of pH on the structure of MjNhaP1was studied in situ in 2D crystals revealing a major change in density within the helix bundle relative to the dimer interface. This change occurred at pH6 and above. The two conformations at low and high pH most likely represent the closed and open states of the antiporter, respectively. This is the first instance where a conformational change associated with the regulation of a secondary transporter appears to map structurally. Reconstruction of 3D map and high-resolution structure by x-ray crystallography would be necessary to understand the mechanism of ion transport and regulation by pH. 2) 2D crystallization of Proline transporter: Proline transporter (PutP) from E.coli belongs the sodium-solute symporter family that includes disease related sodium dependent glucose and iodide transporter in humans. Sodium and proline are co-transported with a stoichiometry of 1:1. Purified PutP was reconstituted to yield 2D crystals that were hexagonal in nature. The 2D crystals had tendency to stack indicating their willingness to form 3D crystals. A projection map of PutP from negatively stained crystals showed trimeric arrangement of protein. Other members of the SSF family have been shown to be monomers. My analysis of oligomeric state of PutP in detergent by blue native gel indicates a monomer in detergent solution. It is likely that PutP can function as a monomer but at higher concentration and in lipid bilayer it tends to form trimer. 3) Oligomeric state and crystallization of carnitine transporter from E.coli: E.coli carnitine transporter (CaiT) belongs to the BCCT (Betaine, Carnitine and Choline) superfamily that transports molecules with quaternary amine groups. CaiT is predicted to span the membrane 12 times and acts as a L-carnitine/g-butyrobetaine exchanger. Unlike other members in this transporter family, it does not require an ion gradient and does not respond to osmotic stress. Over-expression of the protein yielded ~2mg of protein/L of culture. The structure and oligomeric state of the protein were analyzed in detergent and lipid bilayers. Blue native gel electrophoresis indicated that CaiT was a trimer in detergent solution. Gel filtration and cross-linking studies further support this. Reconstitution of CaiT into lipid bilayers resulted in 2D crystals. Analysis of negatively stained 2D crystals confirmed that CaiT is a trimer in the membrane. Initial 3D crystallization trials have been successful and currently, the crystals diffract to 6Å and are being improved. 4) Monomeric porin OmpG: OmpG is a bacterial outer membrane b-barrel protein. It is monomeric and its size (33kDa) places it as a prime candidate for a structural solution, using the recently developed method of solid state NMR (work in collaboration with Prof.Hartmut Oskinat, FMP, Berlin). A long-term aim would be to study porins as templates for designing nanopores, for DNA sequencing and identification. I have expressed OmpG in inclusion bodies and refolded at an efficiency of >90% into a functional form using detergent. OmpG was then crystallized by 2D crystallization yielding an 8Å projection map whose structure was similar to native protein. In addition, these crystals were used for structure determination by solid state NMR. An initial spectrum of heavy isotopically labeled OmpG has allowed identification of specific amino acid residues including threonine and proline. Additionally, I obtained 3D crystals in detergent that diffract to 5.5Å and are being improved.Transporter sind Membranproteine, welche mehrere, die Membran durchspannende, a-Helices aufweisen. Diese beweglichen und vielfältig vorkommenden Proteine ermöglichen durch eine Änderung ihrer Konformation den Transport eines großen Spektrums an verschiedenen Substraten. Zu Beginn meiner Dissertation habe ich an sekundären Transportern, deren 2D Kristallisation mit anschließender elektronenkristallographischer Analyse gearbeitet. Da die mittels Elektronenmikroskopie (EM) erzielte Auflösung begrenzt war, hat sich mein Fokus vor kurzer Zeit zusätzlich auch in Richtung 3D Kristallisation verschoben. Die folgenden Projekte bilden die Basis meiner Doktorarbeit. 1) 2D Kristallisation von MjNhaP1 und pH-Wert induzierte Strukturänderung Der Na+/H+ Antiporter MjNhaP1 ist pH-reguliert und an der Homöostase von H+ und Na+ im hyperthermophilen Archäon Methanococcus jannaschii, dessen optimale Wachstumstemperatur 85°C beträgt, beteiligt. MjNhaP1 wurde in E. coli kloniert und exprimiert. Zweidimensionale Kristalle konnten mit aufgereinigtem Protein bei einem pH-Wert von 4 erhalten werden. Mittels Cryo-Elektronenmikroskopie wurde eine Projektionskarte mit einer Auflösung von 8Å erstellt, welche verlängerte Elektronendichten in der Mitte und strukturierte Elektronendichten zu beiden Seiten des Dimers aufzeigte, die indikativ für ein Bündel aus 4-6 transmembran Helices sind. Der Effekt des pH-Werts auf die Struktur von MjNhaP1 wurde an den 2D Kristallen in-situ untersucht und enthüllte eine deutliche Veränderung der Elektronendichte innerhalb des Helix-Bündels relativ zur Dimergrenze. Diese Veränderung trat ab einem pH-Wert von 6 und darüber auf. Die beiden, bei hohem und niedrigem pH-Wert erhaltenen, Konformationen repräsentieren aller Wahrscheinlichkeit nach den geöffneten beziehungsweise geschlossenen Zustand des Antiporters. Dies ist das erste bekannte Beispiel für eine mit der Regulation eines sekundären Transporters einhergehenden Konformationsänderung, die strukturell dargestellt werden konnte. 2) 2D Kristallisation eines Prolin-Transporters: Der Prolin-Transporter PutP von E. coli gehört zur Familie der Natrium-abhängigen Symporter, welcher auch die für bestimmte Krankheiten beim Menschen relevanten Glukose- und Iodid-Transporter zugehörig sind. Aufgereinigtes PutP wurde rekonstituiert, um hexagonale 2D Kristalle zu erhalten, welche die Tendenz aufwiesen sich übereinander zu Stapeln anzuordnen, was ihre Bereitschaft aufzeigte 3D Kristalle zu bilden. Die Projektionskarte von negativ kontrastierten PutP Kristallen offenbarte eine trimere. Meine Analyse des oligomeren Zustands von in Detergenz gelöstem PutP mittels nativer Gelelektropherese zeigte im Gegensatz zu den 2D Kristallen einen monomeren Zustand auf. Es ist wahrscheinlich, dass PutP als Monomer funktionsfähig ist, aber in höheren Konzentrationen und der Lipiddoppelschicht dazu neigt, Trimere zu bilden. 3) Oligomerer Zustand und Kristallisation des Karnitin-Transporters von E.coli Der Karnitin-Transporter CaiT aus E. coli gehört zur BCCT (Betain, Karnitin und Cholin) Superfamilie, welche Moleküle transportiert, die quaternäre Amingruppen aufweisen. CaiT ist ein L-Karnitin/g-Butyrobetain-Antiporter. Im Gegensatz zu anderen Mitgliedern dieser Transporterfamilie benötigt es keinen Ionengradienten und reagiert nicht auf osmotischen Stress. Die Überexpression des Proteins ergab ~2mg Protein pro Liter Kulturvolumen. Die native Gelelektrophorese zeigte auf, dass CaiT in Detergenzlösung als Trimer vorliegt, was zusätzlich durch Gelfiltrations- und Cross-Linking-Experimente untermauert wurde. Die Rekonstitution von CaiT in eine Lipiddoppelschicht ergab 2D Kristalle, deren Analyse nach der negativen Kontrastierung bestätigte, dass CaiT als Trimer in der Membran vorliegt. Erste Versuche einer 3D Kristallisation waren erfolgreich und ergaben bisher Auflösungen von bis zu 6Å, welche momentan verbessert wird. 4) Monomeres Porin OmpG: OmpG ist ein aus b-Faltblättern bestehendes Protein der äußeren bakteriellen Zellmembran. Es ist monomer und seine Größe (33 kDa) macht es zu einem idealen Kandidaten für die Strukturaufklärung mittels der kürzlich entwickelten Methode der Festkörper-NMR (mit Prof. H. Oschkinat, FMP, Berlin). OmpG wurde von mir in Einschlusskörper exprimiert und durch die Nutzung von Detergenz mit einer Effizienz von mehr als 90% zur funktionell aktiven Form rückgefaltet. Die anschließende 2D Kristallisation von OmpG ergab eine Projektionskarte mit einer Auflösung von 8Å und einer dem nativen Protein ähnlichen Struktur. Außerdem wurden diese Kristalle zur Strukturbestimmung mittels Festkörper-NMR verwendet. Eines der ersten Spektren mit dem Schwerisotopen markiertem OmpG ermöglichte die Identifizierung von spezifischen Aminosäureresten einschließlich Threonin und Prolin. Weiterhin erhielt ich 3D Kristalle in Detergenz, welche bis zu 5,5Å beugten und nun verbessert werden
Effect of different intracanal medicaments on the viability and survival of dental pulp stem cells
No full textBackground: Stem cells play an important role in the success of regenerative endodontic procedures. They are affected by the presence of medicaments that are used before the induction of bleeding or the creation of a scaffold for endodontic regeneration. This study examines the effects of different intracanal medicaments on the viability and survival of dental pulp stem cells at different doses and over different exposure times. Methods: Dental pulp stem cells were cultured from healthy third molar teeth using the long-term explant culture method and characterized using flow cytometry and exposed to different concentrations of calcium hydroxide, doxycycline, potassium iodide, triamcinolone, and glutaraldehyde, each ranging from 0 (control) to 1000 μg/mL. Exposure times were 6, 24, and 48 h. Cell viability was measured using the MTT assay, and apoptosis was measured using the Annexin V-binding assay. Results: All medicaments significantly reduced cell viability at different concentrations over different exposure times. Calcium hydroxide and triamcinolone favored cell viability at higher concentrations during all exposure times compared to other medicaments. The apoptosis assay showed a significant increase in cell death on exposure to doxycycline, potassium iodide, and glutaraldehyde. Conclusion: The intracanal medicaments examined in our study affected the viability of dental pulp stem cells in a time and dose-dependent manner. They also adversely affected the survival of dental pulp stem cells. Further studies are needed to better understand the effect of prolonged exposure to medicaments according to clinical protocols and their effect on the stemness of dental pulp stem cells
Endodontic Management of Dilacerated Maxillary Central Incisor fused to a Supernumerary Tooth using Cone Beam Computed Tomography: An Unusual Clinical Presentation
No full textABSTRACT
Aim
The purpose of this report is to present a case of endodontic management of a dilacerated maxillary central incisor fused to supernumerary tooth unusually appearing as a labial tubercle using cone beam computed tomography (CBCT) as a diagnostic aid.
Background
Anterior teeth are commonly encountered with aberrant anatomical variations in the crown, number of roots, and root canals. Fusion is an infrequent developmental abnormality in shape of the tooth caused by the union of two adjacent tooth germs. A complete knowledge of such complex anatomies is mandatory for a successful root canal treatment. It highlights the endodontic and restorative approach in the functional and esthetic rehabilitation of the involved tooth.
Case report
Three-dimensional imaging using CBCT was used in this case to differentiate single labial canal and palatal C-shaped canal. The endodontic treatment was performed with the aid of dental operating microscope, and the root canals were obturated with a combination of single cone, carrier based, and cold flowable gutta-percha obturation system. The tooth remained asymptomatic without reinfection and symptoms of failure for 18 months.
Conclusion
Cone beam computed tomography is indispensable in treatment planning for cases where the radiographs cannot reveal useful information regarding the root canal shape. Postobturation CBCT has helped in avoiding further retreatment of the tooth, which otherwise is a challenging task.
Clinical significance
The use of sophisticated equipment, such as dental operating microscope and CBCT has helped in accurate diagnosis and treatment planning of fused central incisor respectively.
How to cite this article
Vinothkumar TS, Kandaswamy D, Arathi G, Ramkumar S, Felsypremila G. Endodontic Management of Dilacerated Maxillary Central Incisor fused to a Supernumerary Tooth using Cone Beam Computed Tomography: An Unusual Clinical Presentation. J Contemp Dent Pract 2017;18(6):522-526.
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A systematic review assessing the dental pulp stone prevalence in the Saudi Arabian population
No full textThis Systematic Review (SR) was to report on the prevalence of pulp stones in the Saudi Arabian (KSA) population. The electronic databases were searched for scientific research articles during May 2021. The data search was performed in electronic search engines like PubMed, Scopus, Web of science, and Saudi Digital Library, and 6 original research articles which fulfilled the eligibility criteria were assessed for qualitative data. The prevalence of pulp stones among the KSA population ranged from 4.6% to 50.93% among the study participants and it ranged between 10.2%−13.34% in the teeth assessed. The pulp stones were more frequently reported in decayed teeth, periodontal diseases, attrition, teeth with dental restorations, and higher in the molar teeth in comparison with the premolar teeth. The data on the prevalence of pulp stones among the Saudi population will be helpful for clinicians in planning endodontic procedures
Adipogenic stimulation and pyrrolidine dithiocarbamate induced osteogenic inhibition of dental pulp stem cells is countered by cordycepin
No full textBackground: dental pulp-derived stem cells are easy to access and collect and are an excellent source of stem cells for regenerative therapy. These cells can interact with many biomolecules and scaffolds and can pass on the instructive signals to the sites of regeneration where they are used. In this regard cordycepin, a potential biomolecule derived from medicinal mushrooms with a spectrum of bioactive properties such as antioxidant, anti-inflammatory, and anticancer has not yet been tested for its effect on human dental pulp stem cells. Objective: the objective of the present study was to assess the in vitro adipogenic and osteogenic differentiation potential of human dental pulp stem cells with or without induction after administration of cordycepin. Materials and methods: human dental pulp stem cells DPSCs were isolated from a healthy permanent tooth extracted for orthodontic purposes after obtaining informed consent. Flow cytometry technique was used to assess the surface markers of these cells such as CD73, CD90, and CD105, CD34, CD45, and HLA-DR. Further, an MTT assay was performed on the cells after subjecting them to various concentrations of cordycepin. Following this, the adipogenic and osteogenic potential of the dental pulp stem cells was assessed with or without induction under the influence/absence of 5 μM of cordycepin. The results obtained were statistically analyzed and documented. Results: it was found that the dental pulp stem cells showed strong positive expression for CD73, CD90, and CD105 and faint expression of CD34, CD45, and HLA-DR. MTT assay revealed that 5 μM was the optimum concentration of cordycepin for all the assays. Concerning adipogenesis experiments, there was a statistically significant lowering of all the 4 adipogenesis-related genes PPARγ, FABP4, LPL, and C/EBPα following cordycepin treatment in the presence of induction compared to the only induction group and untreated control cells (p < 0.05). In connection with osteogenesis, was found that there was a statistically significant increase in the expression of RUNX2, COL1A1, OSX and OCN genes along with the increase in alkaline phosphatase and alizarin red staining in the DPSC treated with cordycepin along with the presence of induction and simultaneous addition of PDTC compared to the control untreated cells and cells treated with induction and simultaneous addition of PDTC (p < 0.05). Conclusion: cordycepin can be exploited for its osteopromotive properties and can be used as a bioactive molecule alongside the administration of dental pulp stem cells in the area of regenerative biology and medicine
Effect of Hydroalcoholic Extract of Vitis Vinifera Linn on Female Wistar Rats with Estradiol Valerate Induced Polycystic Ovarian Syndrome
No full textThe present study was undertaken to find out the potential activity of
Vitisviniferalinn against Estrodialvalerateinduced Poly cystic ovary syndrome in
rats.From time immemorial mankind's efforts and ultimate aim have been to seek
eternal happiness. And his endeavour has been to overcome and seek appropriate
remedies for things that stand in his way. Plants have played a weighty role in
maintaining human health and improving the quality of human life for thousands of
years and have several precious components of
medicines,seasonings,beverages,cosmeticsand dyes.Herbal medicines are based on the
premise that plants contain natural substance that can promote health and alleviate
illness.In recent times focus on plant research has increased all over the world and
large evidence has collected to show immense potential of medicinal plants used in
various traditional systems.
Today we are witnessing a great deal of public interest in the use of herbal
remedies.Many western drugs had their origin in plant extract.There are many
herbs,which are preponderantly used to treat cardiovascular problems,liver
disorder,central nervous system,digestive system,metabolic disorders and for
Neuroprotective effects.Given their potential to generate significant therapeutic
effect,they can be useful as drug or supplement in the treatment in the management of
many diseases.Herbal drug or medicinal plants,their extract and isolated compounds
have demonstrated spectrum of biological activities.Such have been used and
continued to be used as medicine in folk-fore or food supplement for various
disorders.
Vitisviniferacontain several medicinally active compounds including
polyphenols(stilbenes and flavanoids), tannins and anthocyanins. Among the plant
part the grape skin has got the highest concentration of polyphenols. The different
parts of the plant Vitisvinifera Linn. has been used in different system of traditional
medication for the treatment of diseases and ailments of human beings. Vitisviniferaon Estrodialvalerate induced PCOSand also planned to study the
changes. Evaluation of stage of Estrous cyclicity by vaginal smear.Evaluation of
Vaginal Cytology.Evaluation of serum Hormonal parameter:
Follicle stimulating hormone, Luteinizing hormone, Estradiol, Progesterone, Testosterone CONCLUSION
In PCOS women, normal gonadotropin-ovarian axis is disturbed. This is
reflected by the higher levels of LH, lower FSH levels and reversal of LH: FSH ratio.
FSH levels in PCOS show lower than normal values whereas after treatment it proves
significant variations. Androgen dynamics involving testosterone doesn’t show any
significant variation. Estrous cycle of the rats was disturbed when they were in
polycystic ovary condition were returned to normalcy after treatments. The
reproductive system and ovary weight of normal rats increased with estradiol valerate
injection which normalizes after treatment withGrape skin extract.Polycyst observed
in all groups except normal control was completely reduced. Polycystic Ovarian
Syndrome (PCOS) is one of the most common female endocrine disorders which may
leads to infertility. Herbal drugs have promising role in treatment of PCOS and shows
steady effect with minimal side effects. Herbal drugs enhance immunity of the body
also regularize menstrual cycle without fluctuating hormonal level. In conclusion
Hydroalcoholic extract of Grape skin extract shows significant recovery of FSH,LH,
estradiol & progesterone and also restored the irregular cycle and ovarian physiology
to normal in the PCOS animals. ThusGrape skin extract was effective in reversing the
hormonal imbalance induced by estradiol valerate in PCOS & validate the use in
treatment of infertility
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