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1.
Subrata Mondal 《Computer methods in biomechanics and biomedical engineering》2013,16(16):1247-1257
AbstractOne of the major causes of implant loosening is due to excessive bone resorption surrounding the implant due to bone remodelling. The objective of the study is to investigate the effects of implant material and implant–bone interface conditions on bone remodelling around tibia bone due to total ankle replacement. Finite element models of intact and implanted ankles were developed using CT scan data sets. Bone remodelling algorithm was used in combination with FE analysis to predict the bone density changes around the ankle joint. Dorsiflexion, neutral, and plantar flexion positions were considered, along with muscle force and ligaments. Implant–bone interfacial conditions were assumed as debonded and bonded to represent non-osseointegration and fully osseointegration at the porous coated surface of the implant. To investigate the effect of implant material, three finite element models having different material combinations of the implant were developed. For model 1, tibial and talar components were made of Co–Cr–Mo, and meniscal bearing was made of UHMWPE. For model 2, tibial and talar components were made of ceramic and meniscal bearing was made of UHMWPE. For model 3, tibial and talar components were made of ceramic and meniscal bearing was made of CFR-PEEK. Changes in implant material showed no significant changes in bone density due to bone remodelling. Therefore, ceramic appears to be a viable alternative to metal and CFR-PEEK can be used in place of UHMWPE. This study also indicates that proper bonding between implant and bone is essential for long-term survival of the prosthetic components. 相似文献
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Cloning and characterization of thermotolerant xylitol dehydrogenases from yeast Pichia angusta 总被引:1,自引:0,他引:1
Dipanwita Biswas Manish Datt Kaliannan Ganesan Alok K. Mondal 《Applied microbiology and biotechnology》2010,88(6):1311-1320
Pichia angusta (syn. Hansenula polymorpha) represents one of the rare yeast that can grow and ferment both xylose and glucose at higher temperature (50°C). However,
little is known about the enzymes involved in xylose utilization from this species. Previous studies indicated the presence
of one xylose reductase and two xylitol dehydrogenase genes in P. angusta. In this study, we have expressed both xylitol dehydrogenases (PaXdh1p and PaXdh2p) in Escherichia coli and purified them as 6X-Histidine-tagged proteins. Biochemical characterization of the recombinant proteins reveals that
both PaXdh1p and PaXdh2p are thermotolerant enzymes. PaXdh2p contains a catalytic and a structural Zn atom. However, the structural
Zn atom is not present in PaXdh1p. Both enzymes also differ in their affinity for the substrate as well as in the catalytic
efficiency. Through mutagenesis and modeling approaches, we have also identified residues important for catalysis and substrate
binding. 相似文献
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This paper deals with the production of pollen grains per anther per flower of 15 probably allergenic pollen producing angiospermic
plant taxa growing in Eastern India. The selected plant taxa includesAilanthus excelsa, Alstonia scholaris, Argemone mexicana, Azadirachta indica, Cassia alata, C. siamea, Dalbergia sissoo, Holarrhena
pubescens, Lagerstroemia speciosa, Madhuca indica, Milletia pinnata, Mimusops elengi, Morus alba, M. indica andMurraya paniculata. Among the investigated taxa,A. excelsa produces the highest number of pollen grains (1635180) followed byC. siamea (1589245) andA. mexicana (463800). The production of pollen grains is lowest inH. pubescens (2500), followed byA. scholaris (5175),A. indica (6220) andM. paniculata (11200). 相似文献
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Shovan Mondal Jean‐Valère Naubron Damien Campolo Michel Giorgi Michéle P. Bertrand Malek Nechab 《Chirality》2013,25(12):832-839
The absolute configurations (AC) of azaheterocylic compounds resulting from the cascade rearrangement of enediynes involving only light atoms were unambiguously assigned by the joint use of vibrational circular dichroism (VCD) and copper radiation single crystal X‐ray diffraction (XRD). These AC determinations proved that the rearrangements of enediynes proceeded with memory of chirality and retention of configuration. Chirality 25:832–839, 2013. © 2013 Wiley Periodicals, Inc. 相似文献
8.
Dipanwita Biswas Manish Datt Monika Aggarwal Alok K. Mondal 《Applied microbiology and biotechnology》2013,97(4):1613-1623
Because of its natural ability to utilize both xylose and arabinose, the halotolerant and osmotolerant yeast Debaryomyces hansenii is considered as a potential microbial platform for exploiting lignocellulosic biomass. To gain better understanding of the xylose metabolism in D. hansenii, we have cloned and characterized a xylitol dehydrogenase gene (DhXDH). The cloned gene appeared to be essential for xylose metabolism in D. hansenii as the deletion of this gene abolished the growth of the cells on xylose. The expression of DhXDH was strongly upregulated in the presence of xylose. Recombinant DhXdhp was expressed and purified from Escherichia coli. DhXdhp was highly active against xylitol and sorbitol as substrate. Our results showed that DhXdhp was thermo-sensitive, and except this, its biochemical properties were quite comparable with XDH from other yeast species. Furthermore, to make this enzyme suitable for metabolic engineering of D. hansenii, we have improved its thermotolerance and modified cofactor requirement through modelling and mutagenesis approach. 相似文献
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Cross-linked enzyme aggregates (CLEAs) are prepared by precipitation of an enzyme and then chemical cross-linking the precipitate. Three CLEAs of lipase with glutaraldehyde concentrations of 10 mM (CLEA A), 40 mM (CLEA B) and 60 mM (CLEA C) were prepared. Studies show that there is a trade-off between thermal stability vs transesterification/hydrolysis rate vs enantioselectivity. The initial rates for transesterification of β-citronellol for the uncross-linked enzyme and CLEAs A, B and C were 243, 167, 102 and 40 µmol mg?1 h?1, respectively. Their thermal stabilities in aqueous media, as reflected by their half-life values at 55°C, were 6, 9, 13 and 16 h, respectively. The enantioselectivity, E values (for kinetic resolution of β-citronellol by transesterification) were 19, 74, 11 and 6, respectively. These results show that CLEA C was the most thermostable; the uncross-linked enzyme was best at obtaining the highest transesterification rate; and CLEA A was best suited for the enantioselective synthesis. Scanning electron microscopy (SEM) showed that the morphology of CLEA was dependent upon the extent of cross-linking. 相似文献
10.
Anthrax, foot and mouth disease (FMD), haemorrhagic septicaemia (HS), peste des petits ruminants (PPR) and rabies are considered to be endemic in Bangladesh. This retrospective study was conducted to understand the geographic and seasonal distribution of these major infectious diseases in livestock based on data collected through passive surveillance from 1 January 2010 to 31 December 2012. Data analysis for this period revealed 5,937 cases of anthrax, 300,333 of FMD, 13,436 of HS, 247,783 of PPR and 14,085 cases of dog bite/rabies. While diseases were reported in almost every district of the country, the highest frequency of occurrence corresponded to the susceptible livestock population in the respective districts. There was no significant difference in the disease occurrences between districts bordering India/Myanmar and non-border districts (p>0.05). Significantly higher (p<0.01) numbers of anthrax (84.5%), FMD (88.3%), HS (84.9%) and dog bite/rabies (64.3%) cases were reported in cattle than any other species. PPR cases were reported mostly (94.8%) in goats with only isolated cases (5.2%) in sheep. The diseases occur throughout the year with peak numbers reported during June through September and lowest during December through April, with significant differences (p<0.01) between the months. The annual usages of vaccines for anthrax, FMD, HS and PPR were only 7.31%, 0.61%, 0.84% and 11.59% of the susceptible livestock population, respectively. Prophylactic vaccination against rabies was 21.16% of cases. There were significant differences (p<0.01) in the administration of anthrax, FMD and HS vaccines between border and non-border districts, but not PPR or rabies vaccines. We recommend that surveillance and reporting of these diseases need to be improved throughout the country. Furthermore, all suspected clinical cases should be confirmed by laboratory examination. The findings of this study can be used in the formulation of more effective disease management and control strategies, including appropriate vaccination policies in Bangladesh. 相似文献