Evaluation of the effects of oral rinses on the retention and surface topography of the ball attachment complex for implant overdentures

Dhanapriya Gopalakrishnan(Dhanapriya Gopalakrishnan ),Azhagarasan Nagarasampatti Sivaprakasam(Azhagarasan Nagarasampatti Sivaprakasam ),Vidhya Jeyapalan(Vidhya Jeyapalan ),Jayakrishnakumar Sampathkuma 대한치과이식임플란트학회 2023 The Korean Academy of Implant Dentistry Vol.42 No.1

Purpose: To evaluate the effect of two different oral rinses on the retention and surface topography of ball attachments for implant overdentures. Materials and Methods: Thirty metal housing and the nylon cap inserts (Adin, Israel) were placed on the master block and the attachment assemblies were transferred to prosthetic blocks using the direct pickup technique. Group I had ten test samples immersed in water, Group II had ten test samples immersed in Listerine® Cool Mint®(J&J, India), Group III had ten test samples immersed in Colgate Vedshakthi oil-based herbal oral rinse (Colgate-Palmolive, India). The retention force was tested at baseline and after immersion in the respective oral rinses at 360 cycles (simulating 3 months) and 720 cycles (simulating 6 months) of clinical use, using a universal testing machine (Shimadzu, AG-X plus 50KN, Europe, GmBH) at a crosshead speed of 50 mm/min. The data was analyzed using the repeated measures ANOVA test, one-way ANOVA test, and post hoc analysis (SPSS23, Munich, Germany). The surface topography was assessed initially and subsequently after immersion in the oral rinses after 360 and 720 insertion-removal cycles using a stereomicroscope (Leica M205C, Germany). Results: At 360 cycles, the mean retention force (MRF) exhibited by Group I was higher than that of Group III and this difference was significant. The MRF of Group II was also significantly higher than Group III. At 720 cycles, the MRF exhibited by Group I was higher than that of Group II and the difference was significant. Also, the MRF of Group I was significantly higher than that of Group III, and the MRF of Group II was significantly higher than that of the Group III test samples. In Group I, the percentage loss in the MRF at the end of 360 and 720 cycles was 4.96% and 6.37%, respectively. In Group II, it was 6.82% and 9.41%, respectively, and in Group III it was 14.75% and. 16.60%, respectively. Conclusions: Colgate Vedshakti caused the highest surface topographic changes. This corroborates with the lower retention obtained, followed by Listerine® Cool Mint®, and the least changes were observed for samples immersed in water, which corroborates with the greater retention obtained in the study.

Modified Chilled Coil Model Development and Application to Turbine Inlet Air Cooling

Gopalakrishnan Anand,Ellen Makar 대한설비공학회 2021 International Journal Of Air-Conditioning and Refr Vol.29 No.1

A Turbine Inlet Air Conditioning (TIAC) system can chill the inlet air of the turbine to maintain maximum turbine performance at all ambient temperatures. However, turbine characteristics, performance guarantees and bell-mouth icing considerations require accurate prediction of the chilling coil performance over a wide range of operating conditions. A modified wet-surface model (MWSM) is developed to more accurately predict the chilling coil performance. The higher accuracy of the model is demonstrated by applying the model to simulate performance data of two different coils. The data covered a wide range of operating conditions with ambient temperature vary from 43.3∘C to 9.7 ∘ C dry bulb and 27.2 ∘C to 6.1 ∘C wet bulb. The turbine flow rate varies from 100% to 43% with chilled air temperature in the range of 3.3–14 ∘ C and chilling load variation of 100% to 5%. The chilled water flow rate varies from 100% to 32% with supply glycol-water temperature in the range of −2.2–6.1 ∘ C. The MWSM uses 11 empirical parameters evaluated from the coil performance data and is able to correlate the data with an adjusted coefficient of determination (R 2 adjRadj2) of over 99%. The higher accuracy of the modified model enables the development of a more robust controls strategy required to maintain the inlet air temperature at the set point with varying ambient temperatures and chilling load conditions. The model can also be applied to other chilling and dehumidification applications especially those experiencing wide variations in operating conditions and load or those requiring close control of the chilling and dehumidification process.

Chilled Coil Performance Control and Application to Turbine Inlet Air Cooling

Gopalakrishnan Anand,Ellen Makar 대한설비공학회 2021 International Journal Of Air-Conditioning and Refr Vol.29 No.2

The Absorption Refrigeration Cycle Turbine Inlet Conditioning (ARCTIC) system can chill the inlet air of the turbine to maintain optimum turbine performance at all ambient temperatures. However, turbine characteristics and bell-mouth icing concerns impose a minimum temperature limitation on the chilled air. Performance guarantees may also require maintaining the inlet air temperature within a narrow range throughout the year. These considerations require accurate prediction of the chilling coil performance over a wide range of operating conditions and the development of a robust controls strategy. A modified wet-surface model is used to model the chilling coil performance. The application of the model to a 2110kW (600 RT) ARCTIC providing inlet air chilling for a MARS 100 turbine is considered. A control strategy is developed to maintain the inlet air temperature at the desired set point with varying ambient temperatures and chilling loads. The TIAC controls help maintain the inlet air temperature at 7.22∘C to maximize turbine capacity and efficiency during most of the hot/warm days and accommodates 100% turndown. Additional safety measures are incorporated to prevent bell-mouth icing.

Isolation, Purification, and Characterization of Haloalkaline Xylanase from a Marine Bacillus pumilus Strain, GESF-1

Gopalakrishnan Menon,Kalpana Mody,Jitendra Keshri 한국생물공학회 2010 Biotechnology and Bioprocess Engineering Vol.15 No.6

A haloalkalitolerant xylanase-producing Bacillus pumilus strain, GESF1 was isolated from an experimental salt farm of CSMCRI. Birch wood xylan and xylose induced maximum xylanase production with considerable activity seen in wheat straw and no activity at all with caboxymethyl cellulose (CMC). A three step purification yielded 21.21-fold purification with a specific activity of 112.42 U/mg protein (unit expressed as μmole of xylose released per min). Xylanase produced showed an optimum activity at pH 8.0, with approximately 50 and 30% relative activity at a pH 6.0 and 10.0, respectively. The temperature optimum was 40°C and kinetic properties such as Km and Vmax were 5.3 mg/mL and 0.42 μmol/min/mL (6593.4μmol/min/mg protein). Xylanase activity (160 ~ 120%)was considerably enhanced in 2.5 to 7.5% NaCl with 87and 73% retention of activity in 10 and 15% of NaCl. Enzyme activity was enhanced by Ca2+, Mn2+, Mg2+, and Na+ but strongly inhibited by heavy metals such as Hg2+,Fe3+, Cu2+, Cd2+, and Zn2+. Organic reagents such as β-Mercaptoethanol enhanced xylanase activity whereas EDTA strongly inhibited its activity. Xylanase, purified from the Bacillus pumilus strain, GESF1 could have potential biotechnological applications.

α-Gal Nanoparticles in CNS Trauma: II. Immunomodulation Following Spinal Cord Injury (SCI) Improves Functional Outcomes

Gopalakrishnan Bhavani,Galili Uri,Saenger Megan,Burket Noah J.,Koss Wendy,Lokender Manjari S.,Wolfe Kaitlyn M.,Husak Samantha J.,Stark Collin J.,Solorio Luis,Cox Abigail,Dunbar August,Shi Riyi,Li Jian 한국조직공학과 재생의학회 2024 조직공학과 재생의학 Vol.21 No.3

BACKGROUND: Previous investigations have shown that local application of nanoparticles presenting the carbohydrate moiety galactose-α-1,3-galactose (α-gal epitopes) enhance wound healing by activating the complement system and recruiting pro-healing macrophages to the injury site. Our companion in vitro paper suggest α-gal epitopes can similarly recruit and polarize human microglia toward a pro-healing phenotype. In this continuation study, we investigate the in vivo implications of α-gal nanoparticle administration directly to the injured spinal cord. METHODS: α-Gal knock-out (KO) mice subjected to spinal cord crush were injected either with saline (control) or with α-gal nanoparticles immediately following injury. Animals were assessed longitudinally with neurobehavioral and histological endpoints. RESULTS: Mice injected with α-gal nanoparticles showed increased recruitment of anti-inflammatory macrophages to the injection site in conjunction with increased production of anti-inflammatory markers and a reduction in apoptosis. Further, the treated group showed increased axonal infiltration into the lesion, a reduction in reactive astrocyte populations and increased angiogenesis. These results translated into improved sensorimotor metrics versus the control group. CONCLUSIONS: Application of α-gal nanoparticles after spinal cord injury (SCI) induces a pro-healing inflammatory response resulting in neuroprotection, improved axonal ingrowth into the lesion and enhanced sensorimotor recovery. The data shows α-gal nanoparticles may be a promising avenue for further study in CNS trauma. BACKGROUND: Previous investigations have shown that local application of nanoparticles presenting the carbohydrate moiety galactose-α-1,3-galactose (α-gal epitopes) enhance wound healing by activating the complement system and recruiting pro-healing macrophages to the injury site. Our companion in vitro paper suggest α-gal epitopes can similarly recruit and polarize human microglia toward a pro-healing phenotype. In this continuation study, we investigate the in vivo implications of α-gal nanoparticle administration directly to the injured spinal cord. METHODS: α-Gal knock-out (KO) mice subjected to spinal cord crush were injected either with saline (control) or with α-gal nanoparticles immediately following injury. Animals were assessed longitudinally with neurobehavioral and histological endpoints. RESULTS: Mice injected with α-gal nanoparticles showed increased recruitment of anti-inflammatory macrophages to the injection site in conjunction with increased production of anti-inflammatory markers and a reduction in apoptosis. Further, the treated group showed increased axonal infiltration into the lesion, a reduction in reactive astrocyte populations and increased angiogenesis. These results translated into improved sensorimotor metrics versus the control group. CONCLUSIONS: Application of α-gal nanoparticles after spinal cord injury (SCI) induces a pro-healing inflammatory response resulting in neuroprotection, improved axonal ingrowth into the lesion and enhanced sensorimotor recovery. The data shows α-gal nanoparticles may be a promising avenue for further study in CNS trauma.

α-Gal Nanoparticles in CNS Trauma: I. In Vitro Activation of Microglia Towards a Pro-Healing State

Gopalakrishnan Bhavani,Galili Uri,Dunbar August,Solorio Luis,Shi Riyi,Li Jianming 한국조직공학과 재생의학회 2024 조직공학과 재생의학 Vol.21 No.3

Background: Macrophages and microglia play critical roles after spinal cord injury (SCI), with the pro-healing, anti-inflammatory (M2) subtype being implicated in tissue repair. We hypothesize that promoting this phenotype within the post-injured cord microenvironment may provide beneficial effects for mitigating tissue damage. As a proof of concept, we propose the use of nanoparticles incorporating the carbohydrate antigen, galactose-α-1,3-galactose (α-gal epitope) as an immunomodulator to transition human microglia (HMC3) cells toward a pro-healing state. Methods: Quiescent HMC3 cells were acutely exposed to α-gal nanoparticles in the presence of human serum and subsequently characterized for changes in cell shape, expression of anti or pro-inflammatory markers, and secretion of phenotype-specific cytokines. Results: HMC3 cells treated with serum activated α-gal nanoparticles exhibited rapid enlargement and shape change in addition to expressing CD68. Moreover, these activated cells showed increased expression of anti-inflammatory markers like Arginase-1 and CD206 without increasing production of pro-inflammatory cytokines TNF-α or IL-6. Conclusion: This study is the first to show that resting human microglia exposed to a complex of α-gal nanoparticles and anti-Gal (from human serum) can be activated and polarized toward a putative M2 state. The data suggests that α-gal nanoparticles may have therapeutic relevance to the CNS microenvironment, in both recruiting and polarizing macrophages/microglia at the application site. The immunomodulatory activity of these α-gal nanoparticles post-SCI is further described in the companion work (Part II). Background: Macrophages and microglia play critical roles after spinal cord injury (SCI), with the pro-healing, anti-inflammatory (M2) subtype being implicated in tissue repair. We hypothesize that promoting this phenotype within the post-injured cord microenvironment may provide beneficial effects for mitigating tissue damage. As a proof of concept, we propose the use of nanoparticles incorporating the carbohydrate antigen, galactose-α-1,3-galactose (α-gal epitope) as an immunomodulator to transition human microglia (HMC3) cells toward a pro-healing state. Methods: Quiescent HMC3 cells were acutely exposed to α-gal nanoparticles in the presence of human serum and subsequently characterized for changes in cell shape, expression of anti or pro-inflammatory markers, and secretion of phenotype-specific cytokines. Results: HMC3 cells treated with serum activated α-gal nanoparticles exhibited rapid enlargement and shape change in addition to expressing CD68. Moreover, these activated cells showed increased expression of anti-inflammatory markers like Arginase-1 and CD206 without increasing production of pro-inflammatory cytokines TNF-α or IL-6. Conclusion: This study is the first to show that resting human microglia exposed to a complex of α-gal nanoparticles and anti-Gal (from human serum) can be activated and polarized toward a putative M2 state. The data suggests that α-gal nanoparticles may have therapeutic relevance to the CNS microenvironment, in both recruiting and polarizing macrophages/microglia at the application site. The immunomodulatory activity of these α-gal nanoparticles post-SCI is further described in the companion work (Part II).

Cell Cycle and Mismatch Repair Genes as Potential Biomarkers in Arabidopsis thaliana Seedlings Exposed to Silver Nanoparticles

Gopalakrishnan Nair, Prakash M.,Chung, Ill-Min Springer-Verlag 2014 Bulletin of environmental contamination and toxico Vol.92 No.6

Copper oxide nanoparticle toxicity in mung bean (Vigna radiata L.) seedlings: physiological and molecular level responses of in vitro grown plants

Gopalakrishnan Nair, P. M.,Kim, S. H.,Chung, I. M. POLISH ACADEMY SCIENCES WARSAW 2014 ACTA PHYSIOLOGIAE PLANTARUM Vol.36 No.11

Modulation of Activator Protein-1 (AP-1) and MAPK Pathway by Flavonoids in Human Prostate Cancer PC3 Cells

Gopalakrishnan, Avanthika,Xu, Chang-Jiang,Nair, Sujit S.,Chen, Chi,Hebbar, Vidya,Kong, Ah-Ng Tony The Pharmaceutical Society of Korea 2006 Archives of Pharmacal Research Vol.29 No.8

In last couple of decades the use of natural compounds like flavonoids as chemopreventive agents has gained much attention. Our current study focuses on identifying chemopreventive flavonoids and their mechanism of action on human prostate cancer cells. Human prostate cancer cells (PC3), stably transfected with activator protein 1 (AP-1) luciferase reporter gene were treated with four main classes of flavonoids namely flavonols, flavones, flavonones, and isoflavones. The maximum AP-1 luciferase induction of about 3 fold over control was observed with $20\;{\mu}M$ concentrations of quercetin, chrysin and genistein and $50\;{\mu}M$ concentration of kaempferol. At higher concentrations, most of the flavonoids demonstrated inhibition of AP-1 activity. The MTS assay for cell viability at 24 h showed that even at a very high concentration $(500\;{\mu}M)$, cell death was minimal for most of the flavonoids. To determine the role of MAPK pathway in the induction of AP-1 by flavonoids, Western blot of phospho MAPK proteins was performed. Four out of the eight flavonoids namely kaempferol, apigenin, genistein and naringenin were used for the Western Blot analysis. Induction of phospho-JNK and phospho-ERK activity was observed after two hour incubation of PC3-AP1 cells with flavonoids. However no induction of phospho-p38 activity was observed. Furthermore, pretreating the cells with specific inhibitors of JNK reduced the AP-1 luciferase activity that was induced by genistein while pretreatment with MEK inhibitor reduced the AP-1 luciferase activity induced by kaempferol. The pharmacological inhibitors did not affect the AP-1 luciferase activity induced by apigenin and naringenin. These results suggest the possible involvement of JNK pathway in genistein induced AP-1 activity while the ERK pathway seems to play an important role in kaempferol induced AP-1 activity.

Subfreezing Absorption Refrigeration for Industrial CHP

Gopalakrishnan Anand,Donald C Erickson,Ellen Makar 대한설비공학회 2018 International Journal Of Air-Conditioning and Refr Vol.26 No.4

The design and operation of an advanced absorption refrigeration unit (Thermochiller) as part of an industrial combined heat and power (CHP) system is presented. The unit is installed at a vegetable processing plant in Santa Maria, California. The overall integrated system includes the engine package with waste heat recovery, Thermochiller, cooling tower, and chilling load interface. The unique feature of the system is that both the exhaust and jacket heat are used to supply subfreezing refrigeration. To achieve the low refrigeration temperatures of interest to industrial applications, all components of this integrated system needed careful consideration and optimization. The CHP system has a low emission natural gas-fired 633kW reciprocating engine cogeneration package. Both the exhaust heat and jacket heat are recovered and delivered via a hot glycol loop with 105 ∘ C supply temperature and 80 ∘C return. The 125 ton ammonia absorption chiller (TC125) chills propylene glycol to −6 ∘ C and has a coefficient of performance of 0.63. TC125 has peak electric demand of 10 kW for pumps and 8 kW for the cooling tower fan. The CHP system, including TC125, operates 20 h per day, six days per week. All operations of TC125 are completely automatic and autonomous, including startups and shutdowns. Industrial refrigeration is typically a 24/7 load and highly energy-intensive. By converting all the engine waste heat to subfreezing refrigeration, Thermochiller brings added value to cogeneration or CHP projects.