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The adaptive response is an error-free DNA repair mechanism induced by low levels of physical or chemical agents. Cells pre-exposed to such agents are resistant to genetic damage induced by subsequent treatment at a high dose. There are many reports on such adaptive responses. Recently we have shown the existence of adaptive responses in vivo in the grasshopper Poecilocerus pictus and the mouse and in vitro in human lymphocytes. Different enzymes are implicated in this DNA repair pathway. In an attempt to understand the molecular mechanism of the methyl methanesulfonate (MMS)-induced adaptive response, the present investigations have been undertaken employing nicotinamide, an inhibitor of the DNA repair enzyme poly(ADP-ribose) polymerase (PARP). Pre-, inter- and post-treatments with nicotinamide of MMS-treated mouse bone marrow cells were carried out. The results revealed that there is a significant reduction in the frequency of chromosomal aberrations compared with combined treatment, suggesting an enhancement of the adaptive response by nicotinamide. Further, the results of NAD+ assay in the inter-treatment experiment showed that there is no depletion of NAD+. Thus, it can be stated that PARP is not involved in the MMS-induced adaptive response in mouse bone marrow cells. 相似文献
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Cleverson Alves da Silva Moura Guilherme Kretzmann Belmonte Pulikanti Guruprasad Reddy Kenneth E. Gonslaves Daniel Eduardo Weibel 《RSC advances》2018,8(20):10930
A detailed investigation to understand the mechanism of the resist action at a fundamental level is essential for future Extreme Ultraviolet Lithography (EUVL) resists. The photodynamics study of a newly developed hybrid nonchemically amplified 2.15%-MAPDSA–MAPDST resist using synchrotron radiation excitation at 103.5 eV (12 nm) is presented. Antimony was incorporated in the resist as a heavy metal absorption center in the form of antimonate (2.15%). The results showed the fast decomposition rate of the radiation sensitive sulfonium triflate. HR-XPS and sulfur L-NEXAFS spectra of the copolymer films revealed that after irradiation the Ar–S+–(CH3)2 sulfonium group bonded to the phenyl ring resisted the EUV excitation. Those results confirmed the polarity switching mechanism from hydrophilic sulfonium triflates to hydrophobic aromatic sulfides obtained in previous results. The inorganic component SbF6− included in the resist formulations as an EUV absorption enhancer was particularly illustrative of the photofragmentation process. F 1s and O 1s HR-XPS spectra showed that fluorine remains linked to the antimony, even after 15 min of irradiation. A change of the antimony oxidation state was also observed with an increase in irradiation time. The presence of the heavy metal may control the high energy deposited on the resist which finally led to very well resolved 20 nm isolated line patterns by EUVL. The 10 times improved sensitivity compared with previous poly-MAPDST resists studied in the past showed the potential of this class of hybrid resists for next generation semiconductor industry applications.Understanding the EUV photofragmentation mechanism in a highly sensitive hybrid n-CAR containing SbF6− as an absorption enhancer. 相似文献
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Cynthia Tsien Huey Tan Sowmya Sharma Naaventhan Palaniyappan Pramudi Wijayasiri Kristel Leung Jatinder Hayre Elizabeth Mowlem Rachel Kang Peter J Eddowes Emilie Wilkes Suresh V Venkatachalapathy Indra N Guha Lilia Antonova Angela C Cheung William JH Griffiths Andrew J Butler Stephen D Ryder Martin W James Guruprasad P Aithal Aloysious D Aravinthan 《Clinical medicine (London, England)》2021,21(1):e32
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Dinesh Singh Chauhan Yadavalli Guruprasad 《Journal of maxillofacial and oral surgery》2015,14(1):42-46
Goldenhar syndrome, a variant of hemifacial microsomia, is a well-known developmental anomaly of maxillofacial skeleton that is apparent at birth. The first and second branchial arch involvement during early embryonic development results in a wide spectrum of anomalies that may include macrostomia and lateral facial clefts. Though clefts of the orofacial region are among the most common congenital facial defects, the occurrence of lateral facial clefts (Tessier 7 cleft) in conditions such as the Goldenhar syndrome, is very rare (<5%). The lateral facial cleft, which results because of improper development of the perioral muscles of the face, gives an appearance of macrostomia giving rise to potential psychological, aesthetic and feeding problems. This clinical report describes the closure of a Tessier 7 cleft and the use of distraction osteogenesis to treat mandibular asymmetry in an 11-year-old female patient with Goldenhar’s syndrome. 相似文献
7.
Mainak Mukhopadhyay Sayak Roy Mridul Bera Guruprasad Bhattacharya 《Current Cardiology Reviews》2020,16(4):341
Introduction Sleep-related problems like sleep apnea are increasing tremendously mostly owing to the disordered lifestyle the present generation is leading which is added like a topping on the base of obesity and metabolic syndrome. The burden on the society is huge taking into consideration the work-time loss and health-related financial issues arising out of these sleep disorders with obstructive sleep apnea (OSA) leading the way. Early diagnosis can prevent several complications of OSA. Cardiovascular diseases, including various arrhythmias, arising due to OSA, are described previously.Case Presentation Herein, an interesting case of OSA, whose pacemaker installation to rectify the long pause could be avoided by simple correction of his OSA using continuous positive airway pressure, is presented. This 49-year-old male patient was diagnosed with severe OSA by using polysomnography and all his significant sinus pauses (highest one with 7.8 sec) during holter ECG monitoring were found to be occurring at night and correcting his OSA with continuous positive airway pressure (CPAP) treatment reverted all those sinus pauses and the need for any further intervention with pacemaker was discarded.Discussion OSA is caused by either partial or complete obstruction of the upper airway, and there is the simultaneously attenuated upper airway dilator muscle tone while the patient is sleeping. The gold standard test designed for the assessment of OSA is polysomnography, as approved by the American Academy of Sleep Medicine and CPAP has been found to be universally beneficial in treating OSA related complications. Physiologically, the ACC/AHA guidelines recommend pacing only in patients with prolonged asymptomatic pauses occurring during wakefulness. This case report proved the above mentioned claim of CPAP treatment. 相似文献
8.
Dinesh Singh Chauhan Yadavalli Guruprasad 《Journal of maxillofacial and oral surgery》2012,11(2):186-190
Background
This study sought to determine the efficacy of cortical tibial bone graft for nasal augmentation. Nine cases of augmentation rhinoplasty with cortical tibial bone graft are presented.Methods
This prospective study evaluated the postoperative results of nine patients who underwent augmentation rhinoplasty using cortical tibial bone graft. There were six males and three females aged between 21 and 36 years (mean age 29). All the nine cases were treated through closed rhinoplasty incisions.Results
Nine patients were operated on and the average follow up was 18 months. The results were favorable. The aesthetic results were gratifying; with good nasal projection in every case without any significant postoperative effects or complications requiring surgery were noted during the follow up.Conclusion
The findings of this study support the use of cortical tibial bone graft for nasal augmentation although further studies with more sample size are required. 相似文献9.
Selvakumar Arumugam Pulikanti Guruprasad Reddy Maria Francis Aditya Kulkarni Sudipta Roy Kartik Chandra Mondal 《RSC advances》2020,10(65):39366
Two alkyl substituted triaryl-cyclopentadienyl ligands [4,4′-(4-phenylcyclopenta-1,3-diene-1,2-diyl)bis(methylbenzene) (1) and 4,4′,4′′-(cyclopenta-1,3-diene-1,2,4-triyl)tris(methylbenzene) (2)] have been synthesized via cross-aldol condensation followed by Zn-dust mediated cyclization and acid catalyzed dehydration reactions. The fluorescence properties of 1 and 2 have been studied in solution and solid state. The ligands exhibited aggregation-induced emission enhancement (AIEE) in THF/water solution. 1 and 2 have been found to be significantly more fluorescent in the solid state than in their respective solutions. This phenomenon can be attributed to the strong intermolecular CH⋯π interactions present in 1 and 2 which leads to the tight packing of molecules in their solid-state. Both 1, 2 and their corresponding anions have been studied by theoretical calculations. Ligands 1 and 2 have been shown to react with anhydrous DyCl3 in the presence of potassium metal at high temperature to afford two fluorescent chloride-bridged tetra-nuclear mixed potassium–dysprosium metallocenes [(Me2Cp)4Dy2IIICl4K2]·3.5(C7H8) (5) and [(Me3Cp)4Dy2IIICl4K2]·3(C7H8) (6), respectively in good yields.Alkyl substituted triaryl-cyclopentadienyl ligands with aggregation-induced emission enhancement (AIEE) properties and their applications in the syntheses of novel chloride bridged tetra-nuclear mixed potassium–dysprosium metallocenes. 相似文献