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51.
William Kelly Jonathan Rubin Jennifer Scully Hari Kamaraju Piotr Wnukowski Ravinder Bhatia 《Biotechnology progress》2016,32(6):1520-1530
Within the last decade, fully disposable centrifuge technologies, fluidized‐bed centrifuges (FBC), have been introduced to the biologics industry. The FBC has found a niche in cell therapy where it is used to collect, concentrate, and then wash mammalian cell product while continuously discarding centrate. The goal of this research was to determine optimum FBC conditions for recovery of live cells, and to develop a mathematical model that can assist with process scaleup. Cell losses can occur during bed formation via flow channels within the bed. Experimental results with the kSep400 centrifuge indicate that, for a given volume processed: the bed height (a bed compactness indicator) is affected by RPM and flowrate, and dead cells are selectively removed during operation. To explain these results, two modeling approaches were used: (i) equating the centrifugal and inertial forces on the cells (i.e., a force balance model or FBM) and (ii) a two‐phase computational fluid dynamics (CFD) model to predict liquid flow patterns and cell retention in the bowl. Both models predicted bed height vs. time reasonably well, though the CFD model proved more accurate. The flow patterns predicted by CFD indicate a Coriolis‐driven flow that enhances uniformity of cells in the bed and may lead to cell losses in the outflow over time. The CFD‐predicted loss of viable cells and selective removal of the dead cells generally agreed with experimental trends, but did over‐predict dead cell loss by up to 3‐fold for some of the conditions. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:1520–1530, 2016 相似文献
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53.
Vijay Kumar Shalini Gour Nidhi Verma Suman Kumar Kundlik Gadhave Pushpendra Mani Mishra Pankaj Goyal Janmejay Pandey Rajanish Giri Jay Kant Yadav 《Journal of peptide science》2019,25(4)
Seminal amyloids are well known for their role in enhancing HIV infection. Among all the amyloidogenic peptides identified in human semen, PAP248‐286 was found to be the most active and was termed as semen‐derived enhancer of viral infection (SEVI). Although amyloidogenic nature of the peptide is mainly linked with enhancement of the viral infection, the most active physiological conformation of the aggregated peptide remains inconclusive. Lipids are known to modulate aggregation pathway of a variety of proteins and peptides and constitute one of the most abundant biomolecules in human semen. PAP248‐286 significantly differs from the other known amyloidogenic peptides, including Aβ and IAPP, in terms of critical concentration, surface charge, fibril morphology, and structural transition during aggregation. Hence, in the present study, we aimed to assess the effect of a lipid, 1,2‐dioleoyl‐sn‐glycero‐3‐phosphocholine (DOPC), on PAP248‐286 aggregation and the consequent conformational outcomes. Our initial observation suggested that the presence of the lipid considerably influenced the aggregation of PAP248‐286. Further, ZDOCK and MD simulation studies of peptide multimerization have suggested that the hydrophobic residues at C‐terminus are crucial for PAP248‐286 aggregation and are anticipated to be major DOPC‐interacting partners. Therefore, we further assessed the aggregation behaviour of C‐terminal (PAP273‐286) fragment of PAP248‐286 and observed that DOPC possesses the ability to interfere with the aggregation behaviour of both the peptides used in the current study. Mechanistically, we propose that the presence of DOPC causes considerable inhibition of the peptide aggregation by interfering with the peptide's disordered state to β‐sheet transition. 相似文献
54.
Marie Paul Audrey Mayi David Forfuet Foncha Cyril Kowo Timoleon Tchuinkam Katherine Brisco Damian Nota Anong Sehgal Ravinder Anthony John Cornel 《Journal of vector ecology》2019,44(2):271-281
Deforestation is a major threat to biodiversity but little data exist on how deforestation in real‐time affects the overall mosquito species community despite its known role in the transmission of diseases. We compared the abundance and diversity of Culex mosquitoes before and after deforestation along a gradient of three different anthropogenic disturbance levels in a tropical rainforest in southwestern Cameroon. The collections were conducted in unlogged forest (January, 2016), selectively logged forest (January, 2017), and within a young palm plantation (October, 2017) using net traps, sweep nets, resting traps, and dipping for immature stages in water bodies. Mosquitoes were morphologically identified to subspecies, groups, and species. A total of 2,556 mosquitoes was collected of which 1,663 (65.06%) belong to the genus Culex, (n=427 (25.68%) in the unlogged forest; n=900 (54.12%) in the selectively logged forest; and n=336 (20.2%) in the young palm plantation) with a significant difference among the habitats. Diversity and richness of mosquitoes varied significantly among habitats with the highest values found in the selectively logged forest (H=2.4; DS=0.87; S=33) and the lowest value in the unlogged forest (H=1.37; DS=0.68; S=13). The results of this study showed that deforestation affects the abundance and diversity of Culex mosquitoes and favors the invasion of anthropophilic mosquitoes. Higher mosquito abundance and diversity in the selectively logged forest than in the pristine forest is notable and some explanations for these differences are discussed. 相似文献
55.
Garsa Anita Kumari Choudhury Prasanta Kumar Puniya Anil Kumar Dhewa Tejpal Malik Ravinder Kumar Tomar Sudhir Kumar 《Probiotics and antimicrobial proteins》2019,11(4):1403-1413
Probiotics and Antimicrobial Proteins - Bovicin is a type AII lantibiotic, possessing two β-methyllanthionine and a disulfide bridge encoded by bovA gene hitherto unknown a couple of decades... 相似文献
56.
Recently, various clinical studies have indicated that lipophilic beta-blockers reduce the coronary mortality in diabetic patients; however, systematic studies have not been reported. The objective of the present investigation was to compare the effects of chronic treatment with metoprolol and atenolol on cardiovascular complications in streptozotocin (STZ)-induced diabetic rats. Injection of STZ produced hyperglycemia, hypoinsulinemia, hyperlipidemia, increased blood pressure, cardiac hypertrophy, reduction in heart rate, and structural alterations in cardiac tissues. Metoprolol and atenolol effectively prevented the development of hypertension in diabetic rats. Metoprolol treatment produced a slight but significant reduction in serum glucose levels with elevation in serum insulin levels, while atenolol produced a slight increase in glucose levels but no effect on insulin levels. Moreover, neither metoprolol nor atenolol treatment reduced the elevated cholesterol levels in diabetic rats. Metoprolol treatment significantly prevented STZ-induced increase in triglyceride levels, but atenolol failed to produce this effect. Metoprolol exhibited a minimal improvement in STZ-induced bradycardia, whereas atenolol produced a further reduction in heart rate. Histological examination showed metoprolol treatment also prevented STZ-induced hypertrophy and some of the alterations in cardiomyocytes. In conclusion, our data suggest that metoprolol has some beneficial effects over atenolol with respect to cardiovascular complications associated with diabetes mellitus. 相似文献
57.
Goyal D Sahoo DK Sahni G 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2007,850(1-2):384-391
The downstream processing of recombinant streptokinase (rSK), a protein used for dissolution of blood clots has been investigated employing Escherichia coli inclusion bodies obtained after direct chemical extraction followed by expanded bed adsorption chromatography (EBAC). Streptokinase was over-expressed using high cell density (final OD(600)=40) culture of recombinant E. coli, and an SK protein concentration of 1080 mg l(-1) was achieved. The wet cell pellet after centrifugation was re-suspended in 8M urea containing buffer resulting in direct extraction of almost 97% of cellular proteins into solution. Compared to mechanical disruption using sonication, the direct extraction helped in simultaneous cell lysis and inclusion body (IB) solubilization in a single integrated step. The post-extraction solution containing cell debris and cellular proteins was diluted and directly loaded on to an EBAC column containing Streamline phenyl, without clarification. By passing the solution four times through the column and using 1M NaCl during loading, 82.7% rSK activity could be recovered in the 10mM sodium phosphate buffer used for elution. A 3-fold increase in specific activity of rSK, from 0.18 x 10(5) in cell lysate to 0.53 x 10(5)IU mg(-1) resulted after this step. rSK was further purified to near-homogeneity (specific activity=0.96 x 10(5)IU mg(-1)) by a subsequent ion-exchange step operated in packed bed mode. An overall downstream recovery of 63% rSK was achieved after EBAC and ion exchange chromatography. The paper thus describes the purification of rSK using a three-step regime involving simple, efficient and highly facile steps. 相似文献
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59.
Venkata N. Are Ashwani Kumar Venuka Durani Goyal Siddhant S. Gotad Biplab Ghosh Rekha Gadre Sahayog N. Jamdar Ravindra D. Makde 《Proteins》2019,87(3):212-225
M24B peptidases cleaving Xaa-Pro bond in dipeptides are prolidases whereas those cleaving this bond in longer peptides are aminopeptidases-P. Bacteria have small aminopeptidases-P (36-39 kDa), which are diverged from canonical aminopeptidase-P of Escherichia coli (50 kDa). Structure-function studies of small aminopeptidases-P are lacking. We report crystal structures of small aminopeptidases-P from E. coli and Deinococcus radiodurans, and report substrate-specificities of these proteins and their ortholog from Mycobacterium tuberculosis. These are aminopeptidases-P, structurally close to small prolidases except for absence of dipeptide-selectivity loop. We noticed absence of this loop and conserved arginine in canonical archaeal prolidase (Maher et al., Biochemistry. 43, 2004, 2771-2783) and questioned its classification. Our enzymatic assays show that this enzyme is an aminopeptidase-P. Further, our mutagenesis studies illuminate importance of DXRY sequence motif in bacterial small aminopeptidases-P and suggest common evolutionary origin with human XPNPEP1/XPNPEP2. Our analyses reveal sequence/structural features distinguishing small aminopeptidases-P from other M24B peptidases. 相似文献
60.
Akhil Kumar Nishank Goyal Nandhini Saranathan Sonam Dhamija Saurabh Saraswat Manoj B Menon Perumal Vivekanandan 《Molecular biology and evolution》2022,39(3)
Depletion of CpG dinucleotides in severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) genomes has been linked to virus evolution, host-switching, virus replication, and innate immune responses. Temporal variations, if any, in the rate of CpG depletion during virus evolution in the host remain poorly understood. Here, we analyzed the CpG content of over 1.4 million full-length SARS-CoV-2 genomes representing over 170 million documented infections during the first 17 months of the pandemic. Our findings suggest that the extent of CpG depletion in SARS-CoV-2 genomes is modest. Interestingly, the rate of CpG depletion is highest during early evolution in humans and it gradually tapers off, almost reaching an equilibrium; this is consistent with adaptations to the human host. Furthermore, within the coding regions, CpG depletion occurs predominantly at codon positions 2-3 and 3-1. Loss of ZAP (Zinc-finger antiviral protein)-binding motifs in SARS-CoV-2 genomes is primarily driven by the loss of the terminal CpG within the motifs. Nonetheless, majority of the CpG depletion in SARS-CoV-2 genomes occurs outside ZAP-binding motifs. SARS-CoV-2 genomes selectively lose CpGs-motifs from a U-rich context; this may help avoid immune recognition by TLR7. SARS-CoV-2 alpha-, beta-, and delta-variants of concern have reduced CpG content compared to sequences from the beginning of the pandemic. In sum, we provide evidence that the rate of CpG depletion in virus genomes is not uniform and it greatly varies over time and during adaptations to the host. This work highlights how temporal variations in selection pressures during virus adaption may impact the rate and the extent of CpG depletion in virus genomes. 相似文献