60 results on '"Amitabha Majumdar"'
Search Results
2. Mrj is a chaperone of the Hsp40 family that regulates Orb2 oligomerization and long-term memory in Drosophila.
- Author
-
Meghal Desai, Hemant, Ankita Deo, Jagyanseni Naik, Prathamesh Dhamale, Avinash Kshirsagar, Tania Bose, and Amitabha Majumdar
- Subjects
Biology (General) ,QH301-705.5 - Abstract
Orb2 the Drosophila homolog of cytoplasmic polyadenylation element binding (CPEB) protein forms prion-like oligomers. These oligomers consist of Orb2A and Orb2B isoforms and their formation is dependent on the oligomerization of the Orb2A isoform. Drosophila with a mutation diminishing Orb2A's prion-like oligomerization forms long-term memory but fails to maintain it over time. Since this prion-like oligomerization of Orb2A plays a crucial role in the maintenance of memory, here, we aim to find what regulates this oligomerization. In an immunoprecipitation-based screen, we identify interactors of Orb2A in the Hsp40 and Hsp70 families of proteins. Among these, we find an Hsp40 family protein Mrj as a regulator of the conversion of Orb2A to its prion-like form. Mrj interacts with Hsp70 proteins and acts as a chaperone by interfering with the aggregation of pathogenic Huntingtin. Unlike its mammalian homolog, we find Drosophila Mrj is neither an essential gene nor causes any gross neurodevelopmental defect. We observe a loss of Mrj results in a reduction in Orb2 oligomers. Further, Mrj knockout exhibits a deficit in long-term memory and our observations suggest Mrj is needed in mushroom body neurons for the regulation of long-term memory. Our work implicates a chaperone Mrj in mechanisms of memory regulation through controlling the oligomerization of Orb2A and its association with the translating ribosomes.
- Published
- 2024
- Full Text
- View/download PDF
3. Niacinamide enhances cathelicidin mediated SARS-CoV-2 membrane disruption
- Author
-
Tanay Bhatt, Binita Dam, Sneha Uday Khedkar, Sahil Lall, Subhashini Pandey, Sunny Kataria, Johan Ajnabi, Shah-E-Jahan Gulzar, Paul M. Dias, Morris Waskar, Janhavi Raut, Varadharajan Sundaramurthy, Praveen Kumar Vemula, Naresh Ghatlia, Amitabha Majumdar, and Colin Jamora
- Subjects
COVID-19 ,SARS-CoV-2 ,antimicrobial peptides ,niacinamide ,LL37 ,skin immunity ,Immunologic diseases. Allergy ,RC581-607 - Abstract
The continual emergence of SARS-CoV-2 variants threatens to compromise the effectiveness of worldwide vaccination programs, and highlights the need for complementary strategies for a sustainable containment plan. An effective approach is to mobilize the body’s own antimicrobial peptides (AMPs), to combat SARS-CoV-2 infection and propagation. We have found that human cathelicidin (LL37), an AMP found at epithelial barriers as well as in various bodily fluids, has the capacity to neutralise multiple strains of SARS-CoV-2. Biophysical and computational studies indicate that LL37’s mechanism of action is through the disruption of the viral membrane. This antiviral activity of LL37 is enhanced by the hydrotropic action of niacinamide, which may increase the bioavailability of the AMP. Interestingly, we observed an inverse correlation between LL37 levels and disease severity of COVID-19 positive patients, suggesting enhancement of AMP response as a potential therapeutic avenue to mitigate disease severity. The combination of niacinamide and LL37 is a potent antiviral formulation that targets viral membranes of various variants and can be an effective strategy to overcome vaccine escape.
- Published
- 2023
- Full Text
- View/download PDF
4. SG-APSIC1137: 12-hydroxystearic acid upregulates skin antimicrobial peptides in skin models and provides long-lasting protection from bacterial challenge from a handwash formulation
- Author
-
Morris Waskar, Xuelan Gu, Tingyan Mi, Meenakshi Swaminathan, Carol Vincent, Rimpa Ghosh, Chandraprabha Doraiswamy, and Amitabha Majumdar
- Subjects
Infectious and parasitic diseases ,RC109-216 ,Public aspects of medicine ,RA1-1270 - Abstract
Objectives: We evaluated the role of 12-hydroxystearic acid (12HSA) in upregulating skin antimicrobial peptides (AMPs) in in vitro and ex vivo assays, and 12HSA provides long-lasting germ protection in vivo through a handwash formulation. Methods: In vitro assays were performed by treating skin cells, maintained in cell-culture media, with 12HSA. After treatment, AMP gene-expression was measured in cells by RT-qPCR, and secreted AMPs in spent cell culture media were analyzed by ELISA. Skin explants were treated with 12HSA, and 3D-living skin equivalent (LSE) models were treated with 12HSA-containing handwash formulations. AMP levels were measured by immunohistochemical staining or RT-qPCR after treatment. In clinical studies, volunteer forearms were washed multiple times with 12HSA-containing handwash in an ethics-approved study in which participants provided informed consent. The washed forearms were challenged with E. coli at different time points after washing. The 12HSA deposition from the formulation was measured using tape strips. Results: Skin cells treated with 12HSA showed increased expression of several AMP genes in vitro, and higher psoriasin AMP secretion was measured in cell-culture media. An enhanced level of LL37 AMP was obtained from the skin epidermis of 12HSA-treated explant skin. AMP genes were also upregulated in the 3D-LSE model treated with a 12HSA-containing handwash formulation. A measurable level of 12HSA was deposited from handwash formulation in the in vivo clinical sample. E. coli recovery from challenged skin was significantly lower at 6 and 10 hours after washing compared to unwashed skin. Conclusions: These data demonstrate that 12HSA boosts skin-AMPs and that a handwash containing 12HSA provides long-lasting germ protection under in vivo test conditions by potentially enhancing skin’s natural immunity. With an emerging understanding of skin’s innate immunity and AMPs, designing cleansing products that strengthen these natural defenses will offer novel approaches to extend hygiene benefits beyond immediate in-wash protection.
- Published
- 2023
- Full Text
- View/download PDF
5. The expanding impact of T-regs in the skin
- Author
-
Edries Yousaf Hajam, Patricia Panikulam, Chung-Ching Chu, Haarshadri Jayaprakash, Amitabha Majumdar, and Colin Jamora
- Subjects
skin ,skin immunology ,skin disease ,regulatory T (Treg) cells ,inflammation ,innate immunity ,Immunologic diseases. Allergy ,RC581-607 - Abstract
As the interface between the body and the environment, the skin functions as the physical barrier against external pathogens and toxic agents. In addition, the skin is an immunologically active organ with a plethora of resident adaptive and innate immune cells, as well as effector molecules that provide another layer of protection in the form of an immune barrier. A major subpopulation of these immune cells are the Foxp3 expressing CD4 T cells or regulatory T cells (T-regs). The canonical function of T-regs is to keep other immune cells in check during homeostasis or to dissipate a robust inflammatory response following pathogen clearance or wound healing. Interestingly, recent data has uncovered unconventional roles that vary between different tissues and we will highlight the emerging non-lymphoid functions of cutaneous T-regs. In light of the novel functions of other immune cells that are routinely being discovered in the skin, their regulation by T-regs implies that T-regs have executive control over a broad swath of biological activities in both homeostasis and disease. The blossoming list of non-inflammatory functions, whether direct or indirect, suggests that the role of T-regs in a regenerative organ such as the skin will be a field ripe for discovery for decades to come.
- Published
- 2022
- Full Text
- View/download PDF
6. Tight Junction barriers in human hair follicles – role of claudin-1
- Author
-
Michaela Zorn-Kruppa, Sabine Vidal-y-Sy, Pia Houdek, Ewa Wladykowski, Stephan Grzybowski, Robert Gruber, Christian Gorzelanny, Jason Harcup, Stefan W. Schneider, Amitabha Majumdar, and Johanna M. Brandner
- Subjects
Medicine ,Science - Abstract
Abstract Barrier function of hair follicles (HFs) is of great interest because they might be an entry port for allergens/pathogens, but could on the other hand be used for drug delivery or vaccination. Therefore we investigated tight junction (TJ) barrier function in human HFs. We show that there is a TJ barrier in the outermost living layer bordering to the environment from the infundibulum to the lower central part and between Henle’s and Huxles layer of anagen HFs. In club hair typical for catagen and telogen HFs a TJ barrier is found surrounding the club. This demonstrates that there is a continuous TJ barrier along interfollicular epidermis and HFs in different phases of HF cycle. However, interestingly, in cell culture experiments we can show that barrier is less tight in HF keratinocytes compared to interfollicular keratinocytes. Knock-down of the TJ protein claudin-1, which we demonstrate here to be less expressed in HFs of lesional atopic dermatitis skin, results in impaired barrier function, decreased proliferation and increased apoptosis of hair keratinocytes. This is in line with a hair growth phenotype in claudin-1 deficient patients (NISCH syndrome) and corresponding knock-out mice and indicates an important role of claudin-1 in HF barrier function and growth.
- Published
- 2018
- Full Text
- View/download PDF
7. Sustained Secretion of the Antimicrobial Peptide S100A7 Is Dependent on the Downregulation of Caspase-8
- Author
-
Tanay Bhatt, Aishwarya Bhosale, Bhavya Bajantri, Mruthyunjaya Swamy Mathapathi, Abrar Rizvi, Giorgio Scita, Amitabha Majumdar, and Colin Jamora
- Subjects
Biology (General) ,QH301-705.5 - Abstract
Summary: Antimicrobial peptides (AMPs) are the body’s natural innate immune defense against a spectrum of pathogens and can also modulate cell proliferation, chemotaxis, angiogenesis, wound healing, and immune cell activity. Harnessing these diverse functions for prophylactic use is contingent upon understanding the regulatory mechanisms governing their unconventional secretion from cells. Analysis of the secretion of S100A7 (Psoriasin), an abundant AMP stored in differentiated keratinocytes of the skin, has revealed an unexpected biphasic secretory response to bacterial exposure. The core components regulating S100A7 secretion are NFκB/p38MAPK, caspase-1, and interleukin (IL)-1α. The initial activation of this core machinery is mediated by Toll-like receptor signaling, whereas the chronic response is mediated by Caspase-8 downregulation. Interestingly, there is a concomitant downregulation of Caspase-8 in inflammatory skin diseases wherein S100A7 is constitutively released. These results highlight the potential of targeting these components to control the release of AMPs from the skin in both homeostatic and disease conditions. : The global explosion of antibiotic-resistant microorganisms has spurred interest in alternative strategies to combat these “superbugs.” Antimicrobial peptides (AMPs) have emerged as a promising solution. Bhatt et al. show downregulation of epidermal caspase-8 can mediate sustained release of AMPs from the skin and provide an effective defense against infection. keywords: caspase, antimicrobial peptides, skin, TLR, IL-1, NFkB, psoriasis, antibiotic resistance
- Published
- 2019
- Full Text
- View/download PDF
8. Molecular Basis of Orb2 Amyloidogenesis and Blockade of Memory Consolidation.
- Author
-
Rubén Hervás, Liying Li, Amitabha Majumdar, María Del Carmen Fernández-Ramírez, Jay R Unruh, Brian D Slaughter, Albert Galera-Prat, Elena Santana, Mari Suzuki, Yoshitaka Nagai, Marta Bruix, Sergio Casas-Tintó, Margarita Menéndez, Douglas V Laurents, Kausik Si, and Mariano Carrión-Vázquez
- Subjects
Biology (General) ,QH301-705.5 - Abstract
Amyloids are ordered protein aggregates that are typically associated with neurodegenerative diseases and cognitive impairment. By contrast, the amyloid-like state of the neuronal RNA binding protein Orb2 in Drosophila was recently implicated in memory consolidation, but it remains unclear what features of this functional amyloid-like protein give rise to such diametrically opposed behaviour. Here, using an array of biophysical, cell biological and behavioural assays we have characterized the structural features of Orb2 from the monomer to the amyloid state. Surprisingly, we find that Orb2 shares many structural traits with pathological amyloids, including the intermediate toxic oligomeric species, which can be sequestered in vivo in hetero-oligomers by pathological amyloids. However, unlike pathological amyloids, Orb2 rapidly forms amyloids and its toxic intermediates are extremely transient, indicating that kinetic parameters differentiate this functional amyloid from pathological amyloids. We also observed that a well-known anti-amyloidogenic peptide interferes with long-term memory in Drosophila. These results provide structural insights into how the amyloid-like state of the Orb2 protein can stabilize memory and be nontoxic. They also provide insight into how amyloid-based diseases may affect memory processes.
- Published
- 2016
- Full Text
- View/download PDF
9. Author Reply to Peer Reviews of Mrj an Hsp40 family chaperone regulates the oligomerization of Orb2 and long-term memory
- Author
-
meghal desai, Hemant Singh, Ankita Deo, Jagyanseni Naik, Tania Bose, and amitabha majumdar
- Published
- 2023
10. Glycerol fermentation by skin bacteria generates lactic acid and upregulates the expression levels of genes associated with the skin barrier function
- Author
-
Neha Salgaonkar, Vinitha Kadamkode, Srikala Kumaran, Prathyusha Mallemala, Ernest Christy, Shanthi Appavoo, Amitabha Majumdar, Rupak Mitra, and Anindya Dasgupta
- Subjects
Glycerol ,Fermentation ,Staphylococcus epidermidis ,Lactic Acid ,Dermatology ,Molecular Biology ,Biochemistry ,Skin - Abstract
Commensal bacteria play a major role in multiple skin functions by providing the first layer of defense against pathogens and maintaining the skin barrier. Staphylococcus epidermidis is one of the most common skin commensals. In this study, we showed that S. epidermidis ferments glycerol and uses it as a nutrient, while producing short-chain and organic fatty acids, with the most notable being lactic acid. Lactic acid is an alpha-hydroxy acid that inhibits the growth of pathogenic bacteria, without any negative effect on the commensal bacteria itself. Using in vivo experiments, we validated our in vitro results, showing that the skin microbiome is also capable of doing this. Finally, using 2D and 3D skin culture models, we showed that the fermentation of glycerol, mainly lactic acid, as determined by analytical methods, upregulates the expression levels of several key genes that are associated with the barrier properties of the skin. While the hydration effect of glycerol on the skin is well known, our study shows the overall benefits of glycerol on the skin microbiome, while revealing an alternate mode of action of glycerol for multiple skin benefits.
- Published
- 2022
11. Small molecules enhance the potency of natural antimicrobial peptides
- Author
-
Valeria Losasso, Khushbu Agarwal, Morris Waskar, Amitabha Majumdar, Jason Crain, Martyn Winn, and Michael Hoptroff
- Subjects
Mammals ,Niacinamide ,Anti-Infective Agents ,Lipid Bilayers ,Biophysics ,Animals ,Humans ,Peptides ,Antimicrobial Peptides - Abstract
The skin-associated microbiome plays an important role in general well-being and in a variety of treatable skin conditions. In this regard, endogenous antimicrobial peptides have both a direct and indirect role in determining the composition of the microbiota. We demonstrate here that certain small molecular species can amplify the antimicrobial potency of naturally occurring antimicrobial peptides. In this study, we have used niacinamide, a form of vitamin B3 naturally found in foods and widely used in cosmetic skincare products, and two of its structural analogs, to investigate their cooperativity with the human antimicrobial peptide LL37 on the bacterium Staphylococcus aureus. We observed a clear synergistic effect of niacinamide and, to some extent, N-methylnicotinamide, whereas isonicotinamide showed no significant cooperativity with LL37. Adaptively biased molecular dynamics simulations using simplified model membrane substrates and single peptides revealed that these molecules partition into the headgroup region of an anionic bilayer used to mimic the bacterial membrane. The simulated effects on the physical properties of the simulated model membrane are well correlated with experimental activity observed in real biological assays despite the simplicity of the model. In contrast, these molecules have little effect on zwitterionic bilayers that mimic a mammalian membrane. We conclude that niacinamide and N-methylnicotinamide can therefore potentiate the activity of host peptides by modulating the physical properties of the bacterial membrane, and to a lesser extent through direct interactions with the peptide. The level of cooperativity is strongly dependent on the detailed chemistry of the additive, suggesting an opportunity to fine-tune the behavior of host peptides.
- Published
- 2022
12. Mrj an Hsp40 family chaperone regulates the oligomerization of Orb2 and long-term memory
- Author
-
Meghal Desai, null Hemant, Ankita Deo, Jagyanseni Naik, Tania Bose, and Amitabha Majumdar
- Abstract
Orb2 the Drosophila homolog of Cytoplasmic polyadenylation element binding protein (CPEB) forms prion-like oligomers. These oligomers consist of Orb2A and Orb2B isoforms and their formation are dependent on the oligomerization of the Orb2A isoform. Drosophila with a mutation diminishing Orb2A’s prion-like oligomerization forms long-term memory but fails to maintain it over time. Since, this prion-like oligomerization of Orb2A plays a crucial role in the maintenance of memory, here we aim to find what regulates this oligomerization. In an immunoprecipitation-based screen, we identify interactors of Orb2A in the Hsp40 and Hsp70 families of proteins. Amongst these, we find an Hsp40 family protein Mrj as a regulator of the conversion of Orb2A to its prion-like form. Mrj interacts with Hsp70 proteins and acts as a chaperone by interfering with the aggregation of pathogenic Huntingtin. Unlike its mammalian homolog, we find Drosophila Mrj is neither an essential gene nor causes any gross neurodevelopmental defect. We observe a loss of Mrj results in a reduction in Orb2 oligomers. Further, the knockdown of Mrj in the mushroom body neurons results in a deficit in long-term memory. Our work implicates a chaperone Mrj in mechanisms of memory regulation through controlling the oligomerization of Orb2A and its association with the translating polysomes.
- Published
- 2022
13. Niacinamide enhances cathelicidin mediated SARS-CoV-2 membrane disruption
- Author
-
Tanay Bhatt, Sneha Uday Khedkar, Binita Dam, Sahil Lall, Subhashini Pandey, Sunny Kataria, Paul M Dias, Morris Waskar, Janhavi Raut, Varadharajan Sundaramurthy, Praveen Kumar Vemula, Naresh Ghatlia, Amitabha Majumdar, and Colin Jamora
- Abstract
The continual emergence of new SARS-CoV-2 variants threatens the effectiveness of worldwide vaccination programs and highlights the need for complementary strategies for a sustainable containment plan. A promising approach is to mobilize the body⍰s own antimicrobial peptides (AMPs), to combat SARS-CoV-2 infection and propagation. We have found that human cathelicidin (LL37), an AMP found at epithelial barriers as well as in various bodily fluids, has the capacity to neutralise multiple strains of SARS-CoV-2. Biophysical and computational studies indicate that LL37⍰s mechanism of action is through the disruption of the viral membrane. This antiviral activity of LL37 is enhanced by the hydrotropic action of niacinamide, which may increase the bioavailability of the AMP. Interestingly, we observed inverse correlation between LL37 levels and disease severity of COVID-19 positive patients, suggesting enhancement of AMP response would be an effective therapeutic avenue to mitigate disease severity and overcome vaccine escape.
- Published
- 2022
14. A role of cellular translation regulation associated with toxic Huntingtin protein
- Author
-
Mrunalini Shinde, Amitabha Majumdar, Vighnesh Ghatpande, Maitheli Sarkar, Ankita Deo, Tania Bose, Anshu Raina, Hiranmay Joag, Ruta Chitale, and Meghal Desai
- Subjects
Pharmacology ,congenital, hereditary, and neonatal diseases and abnormalities ,0303 health sciences ,Huntingtin ,Amyloid ,animal diseases ,030302 biochemistry & molecular biology ,Translation (biology) ,Cell Biology ,Biology ,medicine.disease ,nervous system diseases ,Cell biology ,03 medical and health sciences ,Cellular and Molecular Neuroscience ,nervous system ,Huntington's disease ,mental disorders ,Translational regulation ,medicine ,Protein biosynthesis ,Huntingtin Protein ,Molecular Medicine ,Trinucleotide repeat expansion ,Molecular Biology - Abstract
Huntington’s disease (HD) is a severe neurodegenerative disorder caused by poly Q repeat expansion in the Huntingtin (Htt) gene. While the Htt amyloid aggregates are known to affect many cellular processes, their role in translation has not been addressed. Here we report that pathogenic Htt expression causes a protein synthesis deficit in cells. We find a functional prion-like protein, the translation regulator Orb2, to be sequestered by Htt aggregates in cells. Co-expression of Orb2 can partially rescue the lethality associated with poly Q expanded Htt. These findings can be relevant for HD as human homologs of Orb2 are also sequestered by pathogenic Htt aggregates. Our work suggests that translation dysfunction is one of the contributors to the pathogenesis of HD and new therapies targeting protein synthesis pathways might help to alleviate disease symptoms.
- Published
- 2019
15. A cost-effective and efficient approach for generating and assembling reagents for conducting real-time PCR
- Author
-
Amitabha Majumdar, Vidisha Tripathi, Surya Bansi Singh, Vasudevan Seshadri, Juhi Srivastava, V Shinde Laxmikant, Deepa Subramanyam, Ridim D. Mote, Mahak Tiwari, and Hemant Singh
- Subjects
Moloney murine leukemia virus reverse transcriptase (M-MLV RT) ,Computer science ,SYBR Green I ,General Medicine ,Limiting ,Diamines ,Real-Time Polymerase Chain Reaction ,General Biochemistry, Genetics and Molecular Biology ,Article ,Hot-start Taq polymerase ,Real-time polymerase chain reaction ,In-house PCR mastermix ,Quinolines ,EvaGreen ,Indicators and Reagents ,Biochemical engineering ,Benzothiazoles ,General Agricultural and Biological Sciences ,Real-time PCR - Abstract
Real-time PCR is a widely used technique for quantification of gene expression. However, commercially available kits for real-time PCR are very expensive. The ongoing coronavirus pandemic has severely hampered the economy in a number of developing countries, resulting in a reduction in available research funding. The fallout of this will result in limiting educational institutes and small enterprises from using cutting edge biological techniques such as real-time PCR. Here, we report a cost-effective approach for preparing and assembling cDNA synthesis and real-time PCR mastermixes with similar efficiencies as commercially available kits. Our results thus demonstrate an alternative to commercially available kits. Supplementary Information The online version contains supplementary material available at 10.1007/s12038-021-00231-w.
- Published
- 2021
16. Nup358 regulates remodelling of ER-mitochondrial contact sites and autophagy
- Author
-
Kalarikkal M, Dhamale P, Saikia R, Varshney P, Joseph J, and Amitabha Majumdar
- Subjects
Chemistry ,Autophagy ,AMPK ,Nucleoporin ,Mitochondrion ,VAPB ,mTORC2 ,PI3K/AKT/mTOR pathway ,CAMKK2 ,Cell biology - Abstract
The contact sites between ER and mitochondria regulate several cellular processes including inter-organelle lipid transport, calcium homeostasis and autophagy. However, the mechanisms that regulate the dynamics and functions of these contact sites remain unresolved. We show that annulate lamellae (AL), a relatively unexplored subcellular structure representing subdomains of ER enriched with a subset of nucleoporins, are present at ER-mitochondria contact sites (ERMCS). Depletion of one of the AL-resident nucleoporins, Nup358, results in increased contacts between ER and mitochondria. Mechanistically, Nup358 modulates ERMCS dynamics by restricting mTORC2/Akt signalling. Our results suggest that growth factor-mediated remodelling of ERMCS depends on a reciprocal binding of Nup358 and mTOR to the ERMCS tethering complex consisting of VAPB and PTPIP51. Furthermore, Nup358 also interacts with IP3R, an ERMCS-enriched Ca2+ channel, and controls Ca2+ release from the ER. Consequently, depletion of Nup358 leads to elevated cytoplasmic Ca2+ and autophagy via activation of Ca2+/CaMKK2/AMPK axis. Our study thus uncovers a novel role for AL, particularly for Nup358, in regulating mTORC2-mediated ERMCS remodelling and Ca2+-directed autophagy, possibly via independent mechanisms.
- Published
- 2021
17. A cost-effective and efficient approach for generating and assembling reagents for conducting real-time PCR
- Author
-
Vidisha Tripathi, Amitabha Majumdar, Juhi Srivastava, Ridim D. Mote, Hemant, Mahak Tiwari, Shinde Laxmikant, Vasudevan Seshadri, Surya Bansi Singh, and Deepa Subramanyam
- Subjects
Real-time polymerase chain reaction ,Computer science ,medicine ,Limiting ,Computational biology ,medicine.disease_cause ,Coronavirus - Abstract
Real-time PCR is a widely used technique for quantification of gene expression. However, commercially available kits for real-time PCR are very expensive. The ongoing coronavirus pandemic has severely hampered the economy in a number of developing countries, resulting in a reduction in available research funding. The fallout of this will result in limiting educational institutes and small enterprises from using cutting edge biological techniques such as real-time PCR. Here, we report a cost-effective approach for preparing and assembling cDNA synthesis and real-time PCR mastermixes with similar efficiencies as commercially available kits. Our results thus demonstrate an alternative to commercially available kits.
- Published
- 2021
18. Correction: Keratinocyte differentiation promotes ER stress-dependent lysosome biogenesis
- Author
-
Rezwan Shariff, Sarmistha Mahanty, Mruthyunjaya Mathapathi Swamy, Saloni Patel, Subba Rao Gangi Setty, Amitabha Majumdar, and Shruthi Shirur Dakappa
- Subjects
Keratinocytes ,Cancer Research ,Immunology ,Calcium and vitamin D ,Golgi Apparatus ,TFE3 ,Mechanistic Target of Rapamycin Complex 1 ,Endoplasmic Reticulum ,Cellular and Molecular Neuroscience ,Lysosome ,medicine ,Autophagy ,Humans ,Cytosolic fraction ,Skin ,Microphthalmia-Associated Transcription Factor ,Chemistry ,ADP-Ribosylation Factors ,Basic Helix-Loop-Helix Leucine Zipper Transcription Factors ,Calcium signalling ,Correction ,Cell Differentiation ,Cell Biology ,Endoplasmic Reticulum Stress ,Cell biology ,Activating Transcription Factor 6 ,medicine.anatomical_structure ,Epidermal Cells ,Unfolded protein response ,TFEB ,Calcium ,Keratinocyte differentiation ,Lysosomes ,Biogenesis ,Signal Transduction - Abstract
Keratinocytes maintain epidermal integrity through cellular differentiation. This process enhances intraorganelle digestion in keratinocytes to sustain nutritional and calcium-ionic stresses observed in upper skin layers. However, the molecular mechanisms governing keratinocyte differentiation and concomitant increase in lysosomal function is poorly understood. Here, by using primary neonatal human epidermal keratinocytes, we identified the molecular link between signaling pathways and cellular differentiation/lysosome biogenesis. Incubation of keratinocytes with CaCl
- Published
- 2019
19. A role of cellular translation regulation associated with toxic Huntingtin protein
- Author
-
Hiranmay, Joag, Vighnesh, Ghatpande, Meghal, Desai, Maitheli, Sarkar, Anshu, Raina, Mrunalini, Shinde, Ruta, Chitale, Ankita, Deo, Tania, Bose, and Amitabha, Majumdar
- Subjects
Neurons ,mRNA Cleavage and Polyadenylation Factors ,Huntingtin Protein ,Animals, Genetically Modified ,Huntington Disease ,Polyribosomes ,Protein Biosynthesis ,Animals ,Drosophila Proteins ,Humans ,Protein Isoforms ,Drosophila ,RNA Interference ,RNA, Small Interfering ,Peptides ,Cells, Cultured ,Transcription Factors - Abstract
Huntington's disease (HD) is a severe neurodegenerative disorder caused by poly Q repeat expansion in the Huntingtin (Htt) gene. While the Htt amyloid aggregates are known to affect many cellular processes, their role in translation has not been addressed. Here we report that pathogenic Htt expression causes a protein synthesis deficit in cells. We find a functional prion-like protein, the translation regulator Orb2, to be sequestered by Htt aggregates in cells. Co-expression of Orb2 can partially rescue the lethality associated with poly Q expanded Htt. These findings can be relevant for HD as human homologs of Orb2 are also sequestered by pathogenic Htt aggregates. Our work suggests that translation dysfunction is one of the contributors to the pathogenesis of HD and new therapies targeting protein synthesis pathways might help to alleviate disease symptoms.
- Published
- 2019
20. A role of cellular translation regulation associated with toxic Huntingtin protein
- Author
-
Maitheli Sarkar, Amitabha Majumdar, Tania Bose, Vighnesh Ghatpande, Hiranmay Joag, Mrunalini Shinde, Meghal Desai, and Anshu Raina
- Subjects
0303 health sciences ,congenital, hereditary, and neonatal diseases and abnormalities ,Huntingtin ,Amyloid ,animal diseases ,Translation (biology) ,Biology ,3. Good health ,Cell biology ,nervous system diseases ,03 medical and health sciences ,0302 clinical medicine ,nervous system ,Translational regulation ,mental disorders ,Huntingtin Protein ,Protein biosynthesis ,Trinucleotide repeat expansion ,Gene ,030217 neurology & neurosurgery ,030304 developmental biology - Abstract
Huntington’s disease (HD) is a severe neurodegenerative disorder caused by poly Q repeat expansion in the Huntingtin (Htt) gene. While the Htt amyloid aggregates are known to affect many cellular processes, its role in translation is not addressed. Here we report pathogenic Htt expression causes protein synthesis deficit in cells. We find a functional prion-like protein, the translation regulator Orb2 to be sequestered by Htt aggregates. Coexpression of Orb2 can partially rescue the lethality associated with poly Q expanded Htt. These findings can be relevant for HD as human homologs of Orb2 also can be sequestered by pathogenic Htt aggregates. Our work suggests that translation dysfunction could be one of the contributors in the pathogenesis of HD and new therapies targeting protein synthesis pathways might help alleviate disease symptoms.
- Published
- 2019
- Full Text
- View/download PDF
21. Lysosomal enzyme tripeptidyl peptidase 1 plays a role in degradation of beta amyloid fibrils
- Author
-
Dana Cruz, David E. Sleat, Amitabha Majumdar, Frederick R. Maxfield, Michelle Muldowney, Mukarram El-Banna, and Peter Lobel
- Subjects
Macrophage colony-stimulating factor ,chemistry.chemical_classification ,0303 health sciences ,Microglia ,medicine.disease ,Tripeptidyl peptidase ,Cell biology ,Pathogenesis ,03 medical and health sciences ,0302 clinical medicine ,Enzyme ,medicine.anatomical_structure ,chemistry ,medicine ,Degradation (geology) ,Alzheimer's disease ,Beta (finance) ,030217 neurology & neurosurgery ,030304 developmental biology - Abstract
Alzheimer’s disease (AD) is characterized by the accumulation of amyloid plaques surrounded by microglia. In cell culture, microglia internalize fibrillar β-amyloid but do not degrade it efficiently. Unactivated microglia have a relatively high lysosomal pH, which impairs the activity of lysosomal proteases. Previous studies showed that activation of microglia with macrophage colony stimulating factor decreases lysosomal pH and enhances fibrillar β-amyloid degradation. We investigated the role of the lysosomal protease tripeptidyl peptidase 1 (TPP1) in cell culture and in a mouse model of Alzheimer’s disease. Increased levels of TPP1 in unactivated microglia enhanced fibrillar β-amyloid degradation. Conversely, reduction of TPP1 led to decreased fibrillar β-amyloid degradation in activated microglia, macrophages, and other cells that degrade fibrillar β-amyloid efficiently. Reduction of TPP1 in an AD model mouse using a gene-targeted hypomorphic Tpp1 allele increased plaque burden. These results suggest that decreased TPP1 potentiates AD pathogenesis and that strategies to increase TPP1 activity may have therapeutic value.Highlights*In microglia, TPP1 is important for the degradation of fibrillar β-amyloid.*Increased TPP1 in microglia results in enhanced fibrillar β-amyloid degradation.*In an AD mouse model, reduction of TPP1 led to increased amyloid plaque deposition.
- Published
- 2019
- Full Text
- View/download PDF
22. Sustained Secretion of the Antimicrobial Peptide S100A7 Is Mediated by the Wound Healing Machinery
- Author
-
Colin Jamora, Mruthyunjaya Ms, Giorgio Scita, Bhavya Bajantri, Aishwarya Bhosale, Tanay Bhatt, Abrar Rizvi, and Amitabha Majumdar
- Subjects
S100A7 ,Innate immune system ,Downregulation and upregulation ,Chemistry ,Antimicrobial peptides ,Secretion ,Wound healing ,Intracellular ,Secretory pathway ,Cell biology - Abstract
Antimicrobial peptides (AMPs) are the body’s natural innate immune defense against a spectrum of pathogenic insults and provide an attractive strategy towards combating the growing problem of antibiotic resistant microorganisms. The prophylactic use of AMPs is contingent upon understanding the regulatory mechanisms governing the release of AMPs from intracellular stores, which occurs via the non-conventional secretory pathway. Analysis of S100A7 (Psoriasin), an abundant AMP in the skin, from its endogenous stores within differentiated keratinocytes has revealed an unexpected biphasic secretory response to bacterial exposure. The core components regulating S100A7 secretion are NFκB/p38MAPK, caspase-1 and IL-1α. The early activation of this core machinery is mediated by toll-like receptor signaling, whereas the chronic response is regulated by the wound-healing machinery mediated by Caspase-8 downregulation. Interestingly, in inflammatory skin diseases in which S100A7 is excessively released, there is a concomitant downregulation of caspase-8, indicating that these pathological scenarios are commandeering the normal wound healing response. These results highlight the potential benefits of targeting intracellular wound healing pathways as a means of exerting control over the release of AMPs from the skin in both homeostatic and disease conditions.
- Published
- 2019
23. Sustained Secretion of the Antimicrobial Peptide S100A7 Is Dependent on the Downregulation of Caspase-8
- Author
-
Aishwarya Bhosale, Tanay Bhatt, Mruthyunjaya Swamy Mathapathi, Bhavya Bajantri, Colin Jamora, Abrar Rizvi, Amitabha Majumdar, and Giorgio Scita
- Subjects
0301 basic medicine ,Caspase 8 ,Innate immune system ,Chemistry ,Antimicrobial peptides ,Interleukin ,Down-Regulation ,Chemotaxis ,General Biochemistry, Genetics and Molecular Biology ,S100 Calcium Binding Protein A7 ,Cell biology ,03 medical and health sciences ,030104 developmental biology ,0302 clinical medicine ,Immune system ,lcsh:Biology (General) ,Downregulation and upregulation ,Anti-Infective Agents ,Humans ,Secretion ,lcsh:QH301-705.5 ,030217 neurology & neurosurgery - Abstract
Summary: Antimicrobial peptides (AMPs) are the body’s natural innate immune defense against a spectrum of pathogens and can also modulate cell proliferation, chemotaxis, angiogenesis, wound healing, and immune cell activity. Harnessing these diverse functions for prophylactic use is contingent upon understanding the regulatory mechanisms governing their unconventional secretion from cells. Analysis of the secretion of S100A7 (Psoriasin), an abundant AMP stored in differentiated keratinocytes of the skin, has revealed an unexpected biphasic secretory response to bacterial exposure. The core components regulating S100A7 secretion are NFκB/p38MAPK, caspase-1, and interleukin (IL)-1α. The initial activation of this core machinery is mediated by Toll-like receptor signaling, whereas the chronic response is mediated by Caspase-8 downregulation. Interestingly, there is a concomitant downregulation of Caspase-8 in inflammatory skin diseases wherein S100A7 is constitutively released. These results highlight the potential of targeting these components to control the release of AMPs from the skin in both homeostatic and disease conditions. : The global explosion of antibiotic-resistant microorganisms has spurred interest in alternative strategies to combat these “superbugs.” Antimicrobial peptides (AMPs) have emerged as a promising solution. Bhatt et al. show downregulation of epidermal caspase-8 can mediate sustained release of AMPs from the skin and provide an effective defense against infection. keywords: caspase, antimicrobial peptides, skin, TLR, IL-1, NFkB, psoriasis, antibiotic resistance
- Published
- 2018
24. 16294 Evaluating prebiotic effects of glycerol: Moving toward enhancing the care of infant skin
- Author
-
Neha Salgaonkar, Srikala Kumaran, Stacy Hawkins, Amitabha Majumdar, Anindya Dasgupta, and Prathyusha Mallemala
- Subjects
chemistry.chemical_compound ,chemistry ,business.industry ,Prebiotic ,medicine.medical_treatment ,Glycerol ,medicine ,Dermatology ,Food science ,business - Published
- 2020
25. Niacinamide leave-on formulation provides long-lasting protection against bacteria in vivo
- Author
-
Amitabha Majumdar, Jyoti Kumar Tiwari, Mruthyunjaya Swamy Mathapathi, Vidula Iyer, Shilpa Vora, Amit Chakrabortty, and Prathyusha Mallemalla
- Subjects
0301 basic medicine ,S100A7 ,Innate immune system ,integumentary system ,business.industry ,Antimicrobial peptides ,Human skin ,Dermatology ,Skin infection ,Pharmacology ,medicine.disease ,Antimicrobial ,Biochemistry ,03 medical and health sciences ,030104 developmental biology ,Niacinamide ,medicine ,Skin immunity ,business ,Molecular Biology - Abstract
Antimicrobial peptides (AMPs) form a part of the skin's innate immune system. Their primary activity is to provide antimicrobial benefits and hence protect from infections. AMPs that are present on human skin include psoriasin (S100A7), RNase 7, lysozyme, LL-37 and defensins. Niacinamide is a well-known cosmetic ingredient that has been used traditionally for multiple skin benefits. Recent data indicate that niacinamide treatment can boost AMPs in human gut epithelial cells and in neutrophils. Treatment with niacinamide in mice also provided protection from skin infections by enhancing AMPs. In this article, we find that treatment with niacinamide formulation provides long-lasting protection against bacteria, potentially through the activation of an AMP response.
- Published
- 2017
26. A non-canonical lysosome biogenesis pathway generates Golgi-associated lysosomes during epidermal differentiation
- Author
-
Rezwan Shariff, Saloni Patel, Sarmistha Mahanty, Mruthyunjaya Mathapathi Swamy, Subba Rao Gangi Setty, Amitabha Majumdar, and Shruthi Shirur Dakappa
- Subjects
0303 health sciences ,Chemistry ,Cellular differentiation ,Autophagy ,Golgi apparatus ,Brefeldin A ,Cell biology ,03 medical and health sciences ,symbols.namesake ,chemistry.chemical_compound ,0302 clinical medicine ,medicine.anatomical_structure ,Intracellular organelle ,030220 oncology & carcinogenesis ,Lysosome ,Organelle ,symbols ,medicine ,PI3K/AKT/mTOR pathway ,030304 developmental biology - Abstract
Keratinocytes maintain epidermis integrity and function including physical and antimicrobial barrier through cellular differentiation. This process is predicted to be controlled by calcium ion gradient and nutritional stress. Keratinocytes undergo proteome changes during differentiation, which enhances the intracellular organelle digestion to sustain the stress conditions. However, the molecular mechanism between epidermal differentiation and organelle homeostasis is poorly understood. Here, we used primary neonatal human epidermal keratinocytes to study the link between cellular differentiation, signaling pathways and organelle turnover. Upon addition of calcium chloride (2 mM) to the culture medium, keratinocytes increased their cell size and the expression of differentiation markers. Moreover, differentiated keratinocytes showed enhanced lysosome biogenesis that was dependent on ATF6-arm of UPR signaling but independent of mTOR-MiT/TFE transcription factors. Furthermore, chemical inhibition of mTOR has increased keratinocyte differentiation and relocalized the MiT/TFE TFs to the lysosome membranes, indicating that autophagy activation promotes the epidermal differentiation. Interestingly, differentiation of keratinocytes resulted in dispersal of fragmented Golgi and lysosomes, and the later organelles showed colocalization with Golgi-tethering proteins, suggesting that these lysosomes possibly originated from Golgi, hence named as Golgi-associated lysosomes (GALs). Consistent to this prediction, inhibition of Golgi function using brefeldin A completely abolished the formation of GALs and the keratinocyte differentiation. Thus, ER stress regulates the biogenesis of GALs, which maintains keratinocyte differentiation and epidermal homeostasis.
- Published
- 2018
27. Uterine arteriovenous malformation: A rising cause of postpartum haemorrhage?
- Author
-
Amitabha Majumdar, Thomas E. Mosedale, and Gillian Martin
- Subjects
Adult ,medicine.medical_specialty ,030219 obstetrics & reproductive medicine ,Obstetrics ,business.industry ,Postpartum Hemorrhage ,Obstetrics and Gynecology ,Arteriovenous malformation ,medicine.disease ,Postpartum haemorrhage ,Second pregnancy ,030218 nuclear medicine & medical imaging ,Arteriovenous Malformations ,Uterine Artery ,03 medical and health sciences ,0302 clinical medicine ,Pregnancy ,medicine ,Humans ,Female ,business - Abstract
A 28-year-old gravida 2 para 1 booked under consultant care for her second pregnancy. The patient had had a previous traumatic delivery four years earlier at a different hospital, with a difficult ...
- Published
- 2016
28. The conservative (non-pharmacological) management of female urinary incontinence
- Author
-
Sepeedeh Saleh, Kate Williams, and Amitabha Majumdar
- Subjects
Gynecology ,medicine.medical_specialty ,Modalities ,Referral ,business.industry ,medicine.medical_treatment ,Urinary incontinence ,Audit ,Quality of life (healthcare) ,Weight loss ,medicine ,Smoking cessation ,Patient-reported outcome ,medicine.symptom ,Intensive care medicine ,business - Abstract
Key content Urinary incontinence (UI) affects up to 69% of the female population at some point in their lives but remains under-reported. There are three main types of UI: stress, urgency and mixed. It is recommended to try conservative approaches as first-line measures in the management of all types of UI. These include lifestyle interventions such as adjustment of fluid intake and weight loss, physical and behavioural therapies (pelvic floor muscle training, electrical stimulation, vaginal cones and bladder training programmes) and occasionally containment devices. Initial management of UI, in most cases, renders itself to primary care settings: this involves appropriate assessment of women's symptoms, including quality of life (QOL) assessment, appropriate simple investigations (such as urine analysis) and conservative treatment. Appropriate referral pathways to secondary and tertiary levels of care are necessary. Regular audit should take place to assess the efficacy of management options and referral pathways. UI has significant adverse affects on women's QOL. Hence patient reported outcome measures (PROMs) have been highlighted in recent NHS reports as a means of assessing effectiveness of care from the patient's perspective by gauging patient health status or health-related QOL. Learning objectives To gain an understanding of the assessment and various conservative management options for common types of UI in women. To explore the existing evidence base for such conservative management modalities and to analyse the effect of the current economic climate and reorganisation of services on the conservative management approach. To recognise the important role of patient reported outcome measures as well as service and user involvement, in the assessment of clinical and cost-effectiveness of various treatment options of UI in women. Ethical issues Should conservative measures such as weight loss and smoking cessation be a pre-requisite for offering further management options? In the present climate of scarce health resources should more emphasis be placed on the active role of patients in their own management? Will reorganisation of the NHS pose any threat to the conservative measures for treating UI in women? Is it acceptable to take a ‘one size fits all’ approach to management of common types of UI?
- Published
- 2014
29. Degradation of Alzheimer's amyloid fibrils by microglia requires delivery of ClC-7 to lysosomes
- Author
-
Gunnar K. Gouras, Frederick R. Maxfield, Dana Cruz, Amitabha Majumdar, and Estibaliz Capetillo-Zarate
- Subjects
Macrophage colony-stimulating factor ,Leupeptins ,Mice, Transgenic ,Biology ,Mice ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,Alzheimer Disease ,Chloride Channels ,medicine ,Animals ,Humans ,Macrophage ,Molecular Biology ,Cells, Cultured ,030304 developmental biology ,0303 health sciences ,Amyloid beta-Peptides ,Microglia ,urogenital system ,Macrophage Colony-Stimulating Factor ,Endoplasmic reticulum ,Leupeptin ,Brain ,Lysosome-Associated Membrane Glycoproteins ,Membrane Proteins ,Articles ,Cell Biology ,Hydrogen-Ion Concentration ,Cell biology ,Transport protein ,Protein Transport ,medicine.anatomical_structure ,Membrane protein ,chemistry ,Cell Biology of Disease ,Chloride channel ,RNA Interference ,Lysosomes ,Proteasome Inhibitors ,030217 neurology & neurosurgery - Abstract
Microglial lysosomes lack ClC-7, which leads to incomplete lysosomal acidification. In quiescent microglia, ClC-7 is targeted for proteasomal degradation apparently by an endoplasmic reticulum-associated degradation (ERAD) pathway. Microglial activation recruits ClC-7 to lysosomes and causes lysosomal acidification, which leads to efficient amyloid degradation., Incomplete lysosomal acidification in microglia inhibits the degradation of fibrillar forms of Alzheimer's amyloid β peptide (fAβ). Here we show that in primary microglia a chloride transporter, ClC-7, is not delivered efficiently to lysosomes, causing incomplete lysosomal acidification. ClC-7 protein is synthesized by microglia but it is mistargeted and appears to be degraded by an endoplasmic reticulum–associated degradation pathway. Activation of microglia with macrophage colony-stimulating factor induces trafficking of ClC-7 to lysosomes, leading to lysosomal acidification and increased fAβ degradation. ClC-7 associates with another protein, Ostm1, which plays an important role in its correct lysosomal targeting. Expression of both ClC-7 and Ostm1 is increased in activated microglia, which can account for the increased delivery of ClC-7 to lysosomes. Our findings suggest a novel mechanism of lysosomal pH regulation in activated microglia that is required for fAβ degradation.
- Published
- 2011
30. Aplysia CPEB Can Form Prion-like Multimers in Sensory Neurons that Contribute to Long-Term Facilitation
- Author
-
Eric R. Kandel, Yun-Beom Choi, Amitabha Majumdar, Kausik Si, and Erica White-Grindley
- Subjects
Nervous system ,Amyloid ,Serotonin ,Sensory Receptor Cells ,PROTEINS ,Prions ,Long-Term Potentiation ,Regulator ,Neural facilitation ,MOLNEURO ,General Biochemistry, Genetics and Molecular Biology ,CPEB ,chemistry.chemical_compound ,Aplysia ,medicine ,Animals ,Polylysine ,Neurotransmitter ,mRNA Cleavage and Polyadenylation Factors ,biology ,Biochemistry, Genetics and Molecular Biology(all) ,food and beverages ,Translation (biology) ,Long-term potentiation ,Anatomy ,biology.organism_classification ,Cell biology ,medicine.anatomical_structure ,chemistry ,Synapses ,biology.protein ,CELLBIO - Abstract
SummaryPrions are proteins that can assume at least two distinct conformational states, one of which is dominant and self-perpetuating. Previously we found that a translation regulator CPEB from Aplysia, ApCPEB, that stabilizes activity-dependent changes in synaptic efficacy can display prion-like properties in yeast. Here we find that, when exogenously expressed in sensory neurons, ApCPEB can form an amyloidogenic self-sustaining multimer, consistent with it being a prion-like protein. In addition, we find that conversion of both the exogenous and the endogenous ApCPEB to the multimeric state is enhanced by the neurotransmitter serotonin and that an antibody that recognizes preferentially the multimeric ApCPEB blocks persistence of synaptic facilitation. These results are consistent with the idea that ApCPEB can act as a self-sustaining prion-like protein in the nervous system and thereby might allow the activity-dependent change in synaptic efficacy to persist for long periods of time.PaperClip
- Published
- 2010
- Full Text
- View/download PDF
31. Urodynamics prior to treatment as an intervention: A pilot study
- Author
-
Pallavi Latthe, Philip Toozs-Hobson, and Amitabha Majumdar
- Subjects
Research design ,medicine.medical_specialty ,Randomization ,business.industry ,Urology ,media_common.quotation_subject ,Urinary incontinence ,Logistic regression ,medicine.disease ,Urination ,law.invention ,Clinical trial ,Randomized controlled trial ,Lower urinary tract symptoms ,law ,medicine ,Physical therapy ,Neurology (clinical) ,medicine.symptom ,business ,media_common - Abstract
Aims To evaluate whether the treatment based on urodynamics (UDS) leads to better treatment response compared to where the treatment is based on symptoms alone. Study design, materials and methods All patients referred with lower urinary tract symptoms (LUTS) were offered the opportunity to participate in this patient preference trial. Patients were asked to complete a Kings Health Questionnaire (KHQ) and a 3-day bladder diary. The patients were then offered treatment based on their preference for conservative therapy based on either symptoms alone or with additional UDS or randomization to the same two alternatives, if they had no preference. The primary outcomes studied were improvement in KHQ and reduction in Incontinence Episode Frequency (IEF) at 6 months. Logistic regression analysis was done to evaluate the effect of choice of treatment and effect of incontinence on KHQ. Results There was no statistically significant difference between the KHQ scores pre and post UDS in patient preference or randomized groups. Follow up attendance rates were significantly better in those who chose to undergo urodynamics when compared to those who chose conservative treatment. Conclusions This study suggests although UDS does not improve IEF, it may have utility in patient choice and subsequent compliance. Another relevant finding was the previously unreported high uptake of UDS by women when given the choice of whether to undergo UDS first or have treatment based on symptoms alone. Neurourol. Urodynam. 29:522–526, 2010. © 2009 Wiley-Liss, Inc.
- Published
- 2009
32. Activation of Canadian Coals in a Fixed-Bed Reactor: Effect of the Particle Size on Product Quality
- Author
-
Amitabha Majumdar, Narayan C. Pradhan, Ajay K. Dalai, Eric L. Tollefson, and Jian Liu
- Subjects
Bituminous coal ,Fixed bed ,business.industry ,Chemistry ,General Chemical Engineering ,geology.rock_type ,Metallurgy ,technology, industry, and agriculture ,geology ,Pellets ,Energy Engineering and Power Technology ,Mineralogy ,respiratory system ,complex mixtures ,Bulk density ,respiratory tract diseases ,Fuel Technology ,Asphalt ,otorhinolaryngologic diseases ,medicine ,Coal ,Particle size ,business ,Activated carbon ,medicine.drug - Abstract
Three Canadian coals, namely, Bienfait lignite, Montgomery sub-bituminous C, and Coal Valley high volatile bituminous C were activated in a fixed-bed reactor. For each coal, two different sizes of ...
- Published
- 2008
33. Degradation of fibrillar forms of Alzheimer's amyloid β-peptide by macrophages
- Author
-
Amitabha Majumdar, Peter Lobel, Georgia Dolios, Rong Wang, Frederick R. Maxfield, Haeyong Chung, and Nikiya Asamoah
- Subjects
chemistry.chemical_classification ,Aging ,Amyloid beta-Peptides ,Amyloid ,medicine.diagnostic_test ,Microglia ,Chemistry ,Endosome ,Macrophages ,General Neuroscience ,Proteolysis ,Endocytic cycle ,Peptide ,Article ,Cell biology ,medicine.anatomical_structure ,Biochemistry ,medicine ,Humans ,Phosphorylation ,Neurology (clinical) ,Geriatrics and Gerontology ,Cells, Cultured ,Intracellular ,Developmental Biology - Abstract
Cultured microglia internalize fibrillar amyloid Abeta (fAbeta) and deliver it to lysosomes. Degradation of fAbeta by microglia is incomplete, but macrophages degrade fAbeta efficiently. When mannose-6 phosphorylated lysosomal enzymes were added to the culture medium of microglia, degradation of fAbeta was increased, and the increased degradation was inhibited by excess mannose-6-phosphate, which competes for binding and endocytic uptake. This suggests that low activity of one or more lysosomal enzymes in the microglia was responsible for the poor degradation of fAbeta. To further characterize the degradation of fAbeta in late endosomes and lysosomes, we analyzed fAbeta-derived intracellular degradation products in macrophages and microglia by mass spectrometry. Fragments with truncations in the first 12 N-terminal residues were observed in extracts from both cell types. We also analyzed material released by the cells. Microglia released mainly intact Abeta1-42, whereas macrophages released a variety of N-terminal truncated fragments. These results indicate that initial proteolysis near the N-terminus is similar in both cell types, but microglia are limited in their ability to make further cuts in the fAbeta.
- Published
- 2008
34. Activation of Microglia Acidifies Lysosomes and Leads to Degradation of Alzheimer Amyloid Fibrils
- Author
-
Amitabha Majumdar, Adina R. Buxbaum, Nikiya Asamoah, Peter Lobel, Frederick R. Maxfield, Istvan Sohar, and Dana Cruz
- Subjects
Macrophage colony-stimulating factor ,Ammonium Chloride ,Mice ,Immune system ,Alzheimer Disease ,medicine ,Animals ,Interleukin 6 ,Molecular Biology ,Cells, Cultured ,Amyloid beta-Peptides ,Microglia ,biology ,Interleukin-6 ,Macrophage Colony-Stimulating Factor ,Macrophages ,Articles ,Cell Biology ,Hydrogen-Ion Concentration ,medicine.disease ,Amyloid fibril ,Cyclic AMP-Dependent Protein Kinases ,Amyloid β peptide ,Cell biology ,medicine.anatomical_structure ,Peptide Hydrolases ,biology.protein ,Alzheimer's disease ,Lysosomes - Abstract
Microglia are the main immune cells of the brain, and under some circumstances they can play an important role in removal of fibrillar Alzheimer amyloid beta peptide (fAbeta). Primary mouse microglia can internalize fAbeta, but they do not degrade it efficiently. We compared the level of lysosomal proteases in microglia and J774 macrophages, which can degrade fAbeta efficiently, and we found that microglia actually contain higher levels of many lysosomal proteases than macrophages. However, the microglial lysosomes are less acidic (average pH of approximately 6), reducing the activity of lysosomal enzymes in the cells. Proinflammatory treatments with macrophage colony-stimulating factor (MCSF) or interleukin-6 acidify the lysosomes of microglia and enable them to degrade fAbeta. After treatment with MCSF, the pH of microglial lysosomes is similar to J774 macrophages (pH of approximately 5), and the MCSF-induced acidification can be partially reversed upon treatment with an inhibitor of protein kinase A or with an anion transport inhibitor. Microglia also degrade fAbeta if lysosomes are acidified by an ammonia pulse-wash or by treatment with forskolin, which activates protein kinase A. Our results indicate that regulated lysosomal acidification can potentiate fAbeta degradation by microglia.
- Published
- 2007
35. Current and future trends in the management of overactive bladder
- Author
-
Adrian Wagg, Anand Patel, Simon Hill, Christopher R. Chapple, Philip Toozs-Hobson, and Amitabha Majumdar
- Subjects
medicine.medical_specialty ,Pharmacological therapy ,Urology ,MEDLINE ,Urinary incontinence ,Quality of life ,medicine ,Humans ,Intensive care medicine ,Adverse effect ,Aged ,Aged, 80 and over ,Gynecology ,Urinary bladder ,Urinary Bladder, Overactive ,business.industry ,Obstetrics and Gynecology ,Syndrome ,medicine.disease ,Overactive bladder syndrome ,medicine.anatomical_structure ,Overactive bladder ,Quality of Life ,Female ,medicine.symptom ,business - Abstract
Urinary incontinence is a common problem which increases in prevalence in association with advancing age and has a significant adverse effect upon well-being and quality of life. It is not the "benign" condition that many take it for. Overactive bladder (frequency-urgency syndrome) is the commonest bladder problem in late life, affecting up to 41% of over-75-year-old individuals, and the elderly experience more severe disease. This small series should provide the reader with a comprehensive overview of the current thinking in the assessment and management of patients with overactive bladder syndrome, explores the history of the condition and current approaches to its medical and surgical management and explores where management may change in more complex populations. The current state and future developments in pharmacological therapy are also outlined.
- Published
- 2006
36. Detrusor Overactivity
- Author
-
Amitabha Majumdar and Philip Toozs-Hobson
- Subjects
Obstetrics and Gynecology - Published
- 2004
37. Preface
- Author
-
Andrea Pilkington and Amitabha Majumdar
- Published
- 2014
38. Obstetrics
- Author
-
Amitabha Majumdar and Andrea Pilkington
- Subjects
Varicella-zoster virus VZV ,Small for gestational age fetus ,medicine.medical_specialty ,Obstetrics and gynaecology ,business.industry ,Obstetrics ,Anal sphincter repair ,Jehovah s witness ,Medicine ,Acute management ,business - Published
- 2014
39. Answers
- Author
-
Amitabha Majumdar and Andrea Pilkington
- Subjects
Varicella-zoster virus VZV ,Small for gestational age fetus ,Menstrual bleeding ,business.industry ,Jehovah s witness ,Clobetasol ,Cone biopsy ,Statistics ,Medicine ,Bowel perforation ,Antibiotic use ,business - Published
- 2014
40. Introduction: How to answer EMQs for the MRCOG Part 2 and general revision hints and tips
- Author
-
Amitabha Majumdar and Andrea Pilkington
- Subjects
Computer science ,Calculus ,Algorithm - Published
- 2014
41. EMQs for the MRCOG Part 2
- Author
-
Andrea Pilkington and Amitabha Majumdar
- Subjects
Computer science ,Reading (process) ,media_common.quotation_subject ,Mathematics education ,media_common - Abstract
The EMQ element constitutes 60% of the new MRCOG Part 2 examination. Candidates therefore need to be well-versed in approaching this type of question and extensive practice in answering questions is recommended. This new book contains 150 sample EMQs, together with answers that have full detailed explanations and references for further reading – including RCOG resources such as Green Top Guidelines - to enhance knowledge and understanding. The book also contains a section of handy hints and tips on passing the examination to improve candidates' chances of success. EMQs for the MRCOG Part 2 is an invaluable study aid to help pass the EMQ component of the MRCOG Part 2.
- Published
- 2014
42. The impact of strenuous physical activity on the development of pelvic organ prolapse
- Author
-
Sepeedeh Saleh, M Hill, Amitabha Majumdar, and Simon R. Hill
- Subjects
medicine.medical_specialty ,Pelvic organ ,Pelvic floor ,business.industry ,Physical Exertion ,MEDLINE ,Physical activity ,Obstetrics and Gynecology ,Abdominal pressure ,Pelvic Organ Prolapse ,Surgery ,medicine.anatomical_structure ,Medicine ,Humans ,Female ,business ,Intensive care medicine ,Exercise - Abstract
Pelvic organ prolapse is a common gynaecological problem and the mechanisms underlying prolapse development are not yet clear but it is thought that increases in abdominal pressure, such as those routinely involved in heavy lifting and long periods of standing, may cause progressive pelvic floor damage over time. The aim of this study was to investigate the effects of strenuous physical activity on the development of prolapse. A narrative literature review was carried out to investigate the effects of occupation and recreational activity on the pathogenesis of pelvic organ prolapse. A marked paucity of literature relevant to the research question makes it difficult to draw firm conclusions. Further research is greatly needed to explore potentially preventable factors in this frequently occurring condition. The review reveals some evidence linking strenuous physical activity with pelvic organ prolapse but this is neither consistent nor adequately powered to reach any firm conclusions.
- Published
- 2013
43. Good Amyloid, Bad Amyloid - What's the Difference?
- Author
-
Jay R. Unruh, Douglas V. Laurents, Amitabha Majumdar, Mariano Carrión-Vázquez, Elena Santana, Liying Li, Brian D. Slaughter, Yoshitaka Nagai, María del Carmen Fernández-Ramírez, Marta Bruix, Rubén Hervás, Sergio Casas-Tintó, Mari Suzuki, Margarita Menéndez, Kausik Si, Albert Galera-Prat, and Comunidad de Madrid
- Subjects
Male ,0301 basic medicine ,RNA-binding protein ,Protein aggregation ,Bioinformatics ,Biochemistry ,Cognition ,Learning and Memory ,0302 clinical medicine ,Protein structure ,Yeasts ,Chlorocebus aethiops ,Drosophila Proteins ,Biology (General) ,Long-term memory ,Drosophila Melanogaster ,General Neuroscience ,Proteases ,Animal Models ,Microinjection ,Enzymes ,Precipitation Techniques ,Cell biology ,Insects ,COS Cells ,Physical Sciences ,Female ,Drosophila ,Memory consolidation ,General Agricultural and Biological Sciences ,Oligopeptides ,Drosophila Protein ,Research Article ,Arthropoda ,Amyloid ,QH301-705.5 ,Materials by Structure ,Immunoprecipitation ,Materials Science ,Amyloidogenic Proteins ,Biology ,Research and Analysis Methods ,General Biochemistry, Genetics and Molecular Biology ,03 medical and health sciences ,Model Organisms ,Memory ,mental disorders ,Animals ,Molecular Biology Techniques ,Molecular Biology ,Memory Consolidation ,Long-Term Memory ,mRNA Cleavage and Polyadenylation Factors ,General Immunology and Microbiology ,Organisms ,Biology and Life Sciences ,Proteins ,Invertebrates ,Protein Structure, Tertiary ,030104 developmental biology ,Oligomers ,Mutation ,Enzymology ,Cognitive Science ,030217 neurology & neurosurgery ,Transcription Factors ,Neuroscience - Abstract
Amyloids are ordered protein aggregates that are typically associated with neurodegenerative diseases and cognitive impairment. By contrast, the amyloid-like state of the neuronal RNA binding protein Orb2 in Drosophila was recently implicated in memory consolidation, but it remains unclear what features of this functional amyloid-like protein give rise to such diametrically opposed behaviour. Here, using an array of biophysical, cell biological and behavioural assays we have characterized the structural features of Orb2 from the monomer to the amyloid state. Surprisingly, we find that Orb2 shares many structural traits with pathological amyloids, including the intermediate toxic oligomeric species, which can be sequestered in vivo in hetero-oligomers by pathological amyloids. However, unlike pathological amyloids, Orb2 rapidly forms amyloids and its toxic intermediates are extremely transient, indicating that kinetic parameters differentiate this functional amyloid from pathological amyloids. We also observed that a well-known anti-amyloidogenic peptide interferes with long-term memory in Drosophila. These results provide structural insights into how the amyloid-like state of the Orb2 protein can stabilize memory and be nontoxic. They also provide insight into how amyloid-based diseases may affect memory processes., This research was supported by funds from SAF2013-49179-C2-1-R JPND_CD_FP-688- 059 (AC14/00037 ISCIII) to MCV, SIMR to KS, SAF2013-49179-C2-2-R JPND_CD_FP-688-059 (AC14/00037 ISCIII) to DVL, BFU2012-36825, S2011/BMD-2457 (Comunidad de Madrid)
- Published
- 2016
44. Innovations in the Care of Postoperative Hysterectomy Patients
- Author
-
Amitabha Majumdar and Sepeedeh Saleh
- Subjects
medicine.medical_specialty ,Hysterectomy ,business.industry ,Pelvic pain ,medicine.medical_treatment ,Uterus ,Malignancy ,medicine.disease ,Surgery ,medicine.anatomical_structure ,Menstrual bleeding ,medicine ,Sex organ ,medicine.symptom ,business ,Surgical treatment ,Cervix - Abstract
Hysterectomy, removal of the uterus, has traditionally been regarded as the definitive surgical treatment for heavy menstrual bleeding. And is one of the most commonly performed operations in the UK. (Marjoribanks, 2006) Whilst menstrual disorders are the most frequent reasons for performing hysterectomy other common indications include chronic pelvic pain, fibroids, malignancy of the uterus, cervix or ovaries and genital prolapse. Hysterectomy is a major surgical procedure with potential for significant physical and emotional complications. It also carries additional social and economic costs. (Lethaby, 1999)
- Published
- 2012
45. Psychological Aspects of Hysterectomy & Postoperative Care
- Author
-
Amitabha Majumdar and Sepeedeh Saleh
- Subjects
Female circumcision ,medicine.medical_specialty ,Hysterectomy ,Gynaecological procedures ,business.industry ,Pelvic pain ,medicine.medical_treatment ,Uterine bleeding ,Hormone replacement therapy (menopause) ,Surgery ,medicine ,Psychological aspects ,medicine.symptom ,business - Abstract
Hysterectomy is one of the commonest gynaecological procedures undertaken in the UK and in the USA. (Gupta & Manyonda, 2011) It is carried out both for benign indications (namely abnormal uterine bleeding and pelvic pain) and for malignancies of the female genital tract. In some cases there are multiple indications for hysterectomy, for example, menorrhagia and dysmenorrhoea (Williams & Clark, 2000) and chronic pelvic pain can accompany a variety of other gynaecological diagnoses. Bilateral salpingo-oophrectomy is often carried out concurrently and this may be followed by postoperative commencement of hormone replacement therapy (HRT).
- Published
- 2012
46. 'Like a rabbit from a hat!'--a case of a sacrocolpopexy mesh being taken out by a patient
- Author
-
Sepeedeh Saleh, Amitabha Majumdar, and Simon R. Hill
- Subjects
medicine.medical_specialty ,Time Factors ,business.industry ,Urology ,Obstetrics and Gynecology ,Surgical Mesh ,Pelvic Organ Prolapse ,Surgery ,medicine.anatomical_structure ,Gynecologic Surgical Procedures ,Colposcopy ,Vagina ,Mesh erosion ,Medicine ,Humans ,Female ,business ,Device Removal ,Aged - Abstract
Sacrocolpopexy, be it laparoscopic or abdominal, is associated with a risk of mesh extrusion. We report an interesting case of mesh extrusion with subsequent removal of the mesh from the vagina by the patient. We take this opportunity to review the literature regarding incidence, predisposing factors and complications of sacrocolpopexy mesh extrusion with specific reference to this case.
- Published
- 2011
47. The effects of pressure and temperature on the catalytic oxidation of hydrogen sulfide in natural gas and regeneration of the catalyst to recover the sulfur produced
- Author
-
Amitabha Majumdar, Aminul Islam Chowdhury, Ajay K. Dalai, and Eric L. Tollefson
- Subjects
business.industry ,General Chemical Engineering ,Hydrogen sulfide ,chemistry.chemical_element ,Sulfur ,Material recovery ,Catalysis ,chemistry.chemical_compound ,chemistry ,Catalytic oxidation ,Natural gas ,Medium pressure ,medicine ,business ,Activated carbon ,medicine.drug ,Nuclear chemistry - Abstract
On a etudie l'effet de la pression jusqu'a 5600 kPa et de la temperature jusqu'a 175°C sur l'oxydation de faibles concentrations de H 2 S dans du gaz naturel dans un reacteur a lit fixe sur un catalyseur de charbon active. Ce systeme a la pression de 5600 kPa montre une plus grande activite catalytique (conversion du H 2 S de pratiquement 100%) sur une longue periode et une moins grande selectivite vers SO 2 qu'a la pression atmospherique. La desorption du soufre d'un catalyseur charge se produit d'abord dans les macropores (>100 nm) du catalyseur qui contiennent une part substantielle de la charge de soufre, puis dans les micropores (
- Published
- 1993
48. Inpatient bladder retraining: is it beneficial on its own?
- Author
-
Ismail Hassan, Sepeedeh Saleh, Amitabha Majumdar, and Philip Toozs-Hobson
- Subjects
Adult ,medicine.medical_specialty ,Urology ,Health Behavior ,Urinary incontinence ,urologic and male genital diseases ,Patient Education as Topic ,Behavior Therapy ,medicine ,Humans ,Bladder retraining ,Aged ,Retrospective Studies ,Inpatients ,business.industry ,Urinary Bladder, Overactive ,Obstetrics and Gynecology ,Middle Aged ,female genital diseases and pregnancy complications ,Bladder training ,Urinary Incontinence ,Physical therapy ,Quality of Life ,Female ,Nocturia ,medicine.symptom ,business - Abstract
Urinary incontinence is a common problem with serious effect on the quality of life. Bladder training aims to increase the interval between voids, either by a mandatory or self-adjustable schedule, so that incontinence is avoided. This study aimed to assess the effectiveness of inpatient bladder retraining.A retrospective case-note analysis was conducted over a period of 24 months. Outcome measures were decrease in incontinence episode frequency (IEF) and nocturia and increase in interval between voids. Subjective improvement was assessed on a four-point scale.The study revealed statistically significant decrease in IEF and nocturia and increase in the interval between voids. Twenty-three percent was cured of their symptoms, 36% reported improvement, 27% did not find any change, whereas 14% reported that they were worse off their after bladder retraining.The study confirms the usefulness of inpatient bladder retraining as a treatment option, especially in people refractory to outpatient management.
- Published
- 2009
49. Urodynamics prior to treatment as an intervention: a pilot study
- Author
-
Amitabha, Majumdar, Pallavi, Latthe, and Philip, Toozs-Hobson
- Subjects
Adult ,Urologic Diseases ,Urinary Incontinence, Stress ,Urinary Bladder ,Urination ,Patient Preference ,Pilot Projects ,Middle Aged ,Urodynamics ,Logistic Models ,Treatment Outcome ,Research Design ,Surveys and Questionnaires ,Humans ,Female ,Follow-Up Studies - Abstract
To evaluate whether the treatment based on urodynamics (UDS) leads to better treatment response compared to where the treatment is based on symptoms alone.All patients referred with lower urinary tract symptoms (LUTS) were offered the opportunity to participate in this patient preference trial. Patients were asked to complete a Kings Health Questionnaire (KHQ) and a 3-day bladder diary. The patients were then offered treatment based on their preference for conservative therapy based on either symptoms alone or with additional UDS or randomization to the same two alternatives, if they had no preference. The primary outcomes studied were improvement in KHQ and reduction in Incontinence Episode Frequency (IEF) at 6 months. Logistic regression analysis was done to evaluate the effect of choice of treatment and effect of incontinence on KHQ.There was no statistically significant difference between the KHQ scores pre and post UDS in patient preference or randomized groups. Follow up attendance rates were significantly better in those who chose to undergo urodynamics when compared to those who chose conservative treatment.This study suggests although UDS does not improve IEF, it may have utility in patient choice and subsequent compliance. Another relevant finding was the previously unreported high uptake of UDS by women when given the choice of whether to undergo UDS first or have treatment based on symptoms alone.
- Published
- 2009
50. Drosophila homologue of Eps15 is essential for synaptic vesicle recycling
- Author
-
Amitabha Majumdar, Richa Rikhy, and Shobha Ramagiri
- Subjects
Dynamins ,Mutant ,Endocytic cycle ,Presynaptic Terminals ,Nerve Tissue Proteins ,Pyridinium Compounds ,Neuromuscular junction ,Receptor tyrosine kinase ,Synapse ,Adaptor Protein Complex alpha Subunits ,medicine ,Electroretinography ,Synaptic vesicle recycling ,Animals ,Drosophila Proteins ,N-Ethylmaleimide-Sensitive Proteins ,Dynamin ,biology ,Temperature ,Cell Biology ,Endocytosis ,Cell biology ,Quaternary Ammonium Compounds ,Microscopy, Electron ,medicine.anatomical_structure ,Mutation ,biology.protein ,Phosphorylation ,Drosophila ,Photoreceptor Cells, Invertebrate ,Synaptic Vesicles ,Carrier Proteins ,Protein Binding - Abstract
The mammalian protein Eps15 is phosphorylated by EGF receptor tyrosine kinase and has been shown to interact with several components of the endocytic machinery. We have identified a hypomorphic Eps15 mutant in Drosophila which shows reversible paralysis and an altered physiology at restrictive temperatures. In addition, the temperature-sensitive paralytic defect of shibire mutant is enhanced by this mutant. Eps15 is enriched in the larval neuromuscular junction in endocytic 'hot spots' in a pattern similar to Dynamin. Eps15 mutants show a decrease in the alpha-Adaptin levels at the larval neuromuscular junction synapse. Genetic and biochemical studies of interactions with components of the endocytic machinery suggest that Eps15 has an important role in synaptic vesicle recycling and regulates recruitment of alpha-Adaptin.
- Published
- 2006
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.