20 research outputs found
Human Stem Cell Differentiated Retinal Ganglion Cells for Developing Glaucoma Neuroprotection and Cell Replacement Strategies
No full textProgressive loss of retinal ganglion cells (RGCs) leads to glaucoma. Early diagnosis
offers an opportunity to protect existing RGCs. In advanced glaucoma, most RGCs are lost
causing blindness and cell replacement therapy the only option. We used a human stem
cell-based RGC differentiation model to develop neuroprotection by restoring
mitochondrial homeostasis and enhancing RGC differentiation efficiency to increase the
success of cell replacement therapy.
Unmyelinated axons in RGCs require high levels of ATP, making disrupted
mitochondria a risk factor in glaucoma. Our goal was to restore mitochondrial homeostasis
through mitophagy (mitochondrial autophagy) and mitobiogenesis (mitochondrial
biogenesis). Mutations in the mitophagy protein Optineurin (OPTNE50K) are found in
patients with normal tension glaucoma and hence, we also used RGCs with the E50K
mutation. We discovered that hRGCE50Ks suffer from mitobiogenesis issues, Parkin/Pink
mediated mitophagy defects, and have OPTNE50K-Tank binding kinase-1 (TBK1)
aggregates. hRGCE50Ks have lower mitochondrial mass and a higher mitochondrial load.
We inhibited TBK1 to induce mitochondrial biogenesis and dissolve OPTNE50K-TBK1
aggregates. Our results show TBK1 inhibition triggered mitobiogenesis, dissolved
aggregates, decreased mitochondrial ATP production load, and increased spare respiratory
capacity, leading to neuroprotection. With complete RGC loss, enhancing differentiation to progenitor cells with lower
cell division capacity can improve the success of cell replacement therapy and reduce
teratoma formation and poor tissue integration. We observed that stem cells use
proteasomes for mitochondrial degradation, while hRGCs use the lysosomal mitophagy
pathway. Our results indicate that proteasomal activity declines during differentiation to
hRGCs. Inhibition of proteasomal activity during early differentiation resulted in higher
and faster RGC differentiation, with similar effects seen in motor neuron differentiation.
We did not observe metabolic reprogramming in differentiating cells upon proteasomal
activity inhibition but saw changes in cell cycle distribution, specifically an increase in the
number of cells in the G1 phase. Proteomics analysis post-inhibitory treatment showed
elevated neuronal differentiation proteins. Our results can be translated to minimize
injection cell numbers and other risks of cell replacement therapy.
In summary, my research identifies novel mechanisms for restoring mitochondrial
homeostasis for neuroprotection in glaucomatous RGCs and develops an enhanced
differentiation strategy to aid the success of cell replacement therapy
Human Stem Cell Differentiated Retinal Ganglion Cells for Developing Glaucoma Neuroprotection and Cell Replacement Strategies
No full textProgressive loss of retinal ganglion cells (RGCs) leads to glaucoma. Early diagnosis
offers an opportunity to protect existing RGCs. In advanced glaucoma, most RGCs are lost
causing blindness and cell replacement therapy the only option. We used a human stem
cell-based RGC differentiation model to develop neuroprotection by restoring
mitochondrial homeostasis and enhancing RGC differentiation efficiency to increase the
success of cell replacement therapy.
Unmyelinated axons in RGCs require high levels of ATP, making disrupted
mitochondria a risk factor in glaucoma. Our goal was to restore mitochondrial homeostasis
through mitophagy (mitochondrial autophagy) and mitobiogenesis (mitochondrial
biogenesis). Mutations in the mitophagy protein Optineurin (OPTNE50K) are found in
patients with normal tension glaucoma and hence, we also used RGCs with the E50K
mutation. We discovered that hRGCE50Ks suffer from mitobiogenesis issues, Parkin/Pink
mediated mitophagy defects, and have OPTNE50K-Tank binding kinase-1 (TBK1)
aggregates. hRGCE50Ks have lower mitochondrial mass and a higher mitochondrial load.
We inhibited TBK1 to induce mitochondrial biogenesis and dissolve OPTNE50K-TBK1
aggregates. Our results show TBK1 inhibition triggered mitobiogenesis, dissolved
aggregates, decreased mitochondrial ATP production load, and increased spare respiratory
capacity, leading to neuroprotection. With complete RGC loss, enhancing differentiation to progenitor cells with lower
cell division capacity can improve the success of cell replacement therapy and reduce
teratoma formation and poor tissue integration. We observed that stem cells use
proteasomes for mitochondrial degradation, while hRGCs use the lysosomal mitophagy
pathway. Our results indicate that proteasomal activity declines during differentiation to
hRGCs. Inhibition of proteasomal activity during early differentiation resulted in higher
and faster RGC differentiation, with similar effects seen in motor neuron differentiation.
We did not observe metabolic reprogramming in differentiating cells upon proteasomal
activity inhibition but saw changes in cell cycle distribution, specifically an increase in the
number of cells in the G1 phase. Proteomics analysis post-inhibitory treatment showed
elevated neuronal differentiation proteins. Our results can be translated to minimize
injection cell numbers and other risks of cell replacement therapy.
In summary, my research identifies novel mechanisms for restoring mitochondrial
homeostasis for neuroprotection in glaucomatous RGCs and develops an enhanced
differentiation strategy to aid the success of cell replacement therapy
Arp2/3 mediated dynamic lamellipodia of the hPSC colony edges promote liposome-based DNA delivery
No full textCationic liposome-mediated delivery of drugs, DNA, or RNA plays a pivotal role in small molecule therapy, gene editing, and immunization. However, our current knowledge regarding the cellular structures that facilitate this process remains limited. Here, we used human pluripotent stem cells (hPSCs), which form compact colonies consisting of dynamically active cells at the periphery and epithelial-like cells at the core. We discovered that cells at the colony edges selectively got transfected by cationic liposomes through actin-related protein 2/3 (Arp2/3) dependent dynamic lamellipodia, which is augmented by myosin II inhibition. Conversely, cells at the core establish tight junctions at their apical surfaces, impeding liposomal access to the basal lamellipodia and thereby inhibiting transfection. In contrast, liposomes incorporating mannosylated lipids are internalized throughout the entire colony via receptor-mediated endocytosis. These findings contribute a novel mechanistic insight into enhancing therapeutic delivery via liposomes, particularly in cell types characterized by dynamic lamellipodia, such as immune cells or those comprising the epithelial layer
Does Outward Foreign Direct Investment Reduce Domestic Investment?: An Industry-Level Analysis
No full textWith the rise of globalisation, countries have become more connected financially and global cross-border investment flows have become more common. FDI is an important form of cross-border flow which is responsible for the spread of technology across countries and is the main source of external finance for emerging countries. In the last two decades, FDI has increased tremendously. But this has been accompanied by fears about outward FDI taking away production activities and jobs away from the home country. I look at how outward FDI affects home country investment. One can intuitively understand that a dollar of money spent abroad means a dollar less to invest in the domestic economy. Based on the theory of the financially constrained firm, I hypothesize that outward FDI reduces domestic fixed capital investment and R&D spending. I also develop a theoretical framework to distinguish the varying effects of outward FDI on domestic investment across traditional and R&D-intensive industries.By using industry-level panel data for 18 OECD countries covering the period 1995-2009, I regressed the shares of Gross Fixed Capital Formation (GFCF) and R&D spending separately on the share of outward FDI both for all industries as well as specifically for traditional and R&D-intensive industries. While, outward FDI had a negative effect on domestic capital investments at the aggregate level, it did not have any significant effect while looking at specific industry types. This could be because of the reduced sample size in the individual types. Outward FDI had a negative effect on domestic R&D spending at the aggregate level and for R&D-intensive industries, but it had a positive effect for traditional industries. Thus, while fears about outward FDI taking away domestic fixed capital investments are valid, outward FDI can have both a positive and negative effect on R&D expenditure, depending on the type of industry. These results can help MNCs make strategic investment decisions taking into account their effect on their home country industry. It can also help policymakers formulate tax and industrial policies to promote home country investments.Management of Technology (MoT
Study of crystal structure and unique photoluminescence properties of Eu2-xFexO3 (x = 0 – 0.5) orthoferrites
No full textGlaucomatous E50K Mutation in the Optineurin Gene Causes Mitophagy Defects for Retinal Ganglion Cells but Not for Motor Neurons
No full textBackground: Clearance of damaged mitochondria by lysosomes, known as mitophagy, is critical for maintaining mitochondrial homeostasis and cellular energy balance. Optineurin (Optn) is the central player for mitophagy found to be mutated among normal tension glaucoma (OPTNE50K) and in some familial forms of amyotrophic lateral sclerosis (OPTNE478G) patients. It is critical to understand how mitophagy mechanisms are altered for these inherited mutations in stem cells and differentiated neurons to gain insight into the disease’s developmental aspect.
Methods: We utilized human embryonic stem cell-derived retinal ganglion cells (hRGCs) and induced motor neurons (iMNs) with and without the OPTNE50K mutation. The cells were treated with DMSO (vehicle control) or with 10 M CCCP, an uncoupler that induces mitochondrial damage. We then analyzed the activation status of critical mitophagy players including Optn, Parkin, Pink and Lc3b. We further analyzed if OptnE50K mutant forms aggregate in iMNs as observed for hRGCs.
Results: We found that OPTNE50K mutation causes attenuated activation for Optn, Parkin, and LC3b in hRGCs under mitochondrial damage, while iMNs and hPSCs maintained healthy mitophagy. Additionally, mutant iMNs do not display distinct Optineurin aggregates, unlike in mutant hRGCs.
Conclusion: Our results suggest that the OptnE50K mutation may disrupt mitophagy in hRGCs but not in iMNs and stem cells. In addition, the lack of Optn aggregates in the OPTNE50K mutant iMNs suggests an alternative pathway that inhibits the aggregate formation, presumably for maintaining healthy mitophagy for longer survival.
Impact: The results from this project lay the groundwork for further investigation of the mechanisms behind mitophagy and its relation to glaucoma and ALS. Understanding what causes certain cell types to degrade while others remain healthy is key to understanding the genotype-phenotype specificity for inherited gene disorders
Personality and the type of offences committed by juvenile delinquents
No full textThis research study was mooted with the belief that criminal activity on the part of children and adolescents represents one of our most significant social issues. One of the most prominent manifestations is that children and adolescents constitute the primary focus of family life. This study attempted to find out the characteristics of a sample of 70 juvenile delinquents who are incarcerated at the Singapore Boys' Home for offences for theft, rioting and sex-related, such as, outrage of modesty and selling non-print pornographic materials.The author used two instruments, the Risks and Needs Assessment Checklist which is used by the Singapore Boys' Home and a psychological test, the 16 Personality Factor Test for this study. It was found that 70% of the subjects had involved in smoking, consumption of drugs and alcohol, substance abuse, sexual behaviour and gangs. Generally most juvenile delinquents reported that their mother and father allowed them "to do what they want". Two contrasting types of parents' marital relationship reported by the delinquents were that their parents were "supportive of each other" and had "little verbal exchange, high conflict". Most subjects also reported that there were some disorganisations or stress at home. Parallel with this, majority of the subjects also revealed that they had connections with gangs and had friends who were also gang members. Interestingly, a great proportion of the juvenile delinquents were early school drop-outs as they had only seven to eight years of schooling. As compared to the theft offenders, the non-theft offenders obtained a slightly higher mean score on almost all the factors. A comparison between the rioters and non-rioters indicates that the rioters scored significantly higher for Factor Q1 (Radicalism) personality trait. As for the sex-related and non-sex-related offenders, no significant differences in personality were observed. Nevertheless, the sex-related offenders showed a slightly higher mean score on Factor G and Factor O. Generally all the offenders exhibited low self-control.The findings of this study indicate several implications. Firstly, several agencies, namely, the schools, counselling centres and the law enforcement authorities need to work hand-in-hand to identify "at-risk" juveniles and cater programmes to suit their needs. Secondly, the importance of family dynamics have to be emphasized. Thirdly, it is important to do further research concerning which dimensions of personality are most strongly related to offences or antisocial behaviours and how they may contribute to the prevention and intervention of offenders. This may be useful for future rehabilitation policy formulation in Singapore
'Aanmavin Raagangal', A catalyst to provoke Humanitarianism and Patriotism
No full textA song sung by a soul which sacrificed himself publicly for the freedom of India and by the soul which sacrificed herself privately for the freedom of India is the centre and apex of the Novel ‘Aanmavin Raagangal’. The sweet characters of these two souls kindle us to read this novel continually. From this Novel, we can clearly understand the Patriotism and Humanitarianism of the author, Na. Parthasarathy. This novel portrays the nature of selfless people in the period of freedom struggle of India and the selfish people of the corrupted politics at present. The study calls us to get rid of all social evils at present and also insist us to imbibe the patriotism and humanitarianism
Efficacy of Intra-Articular Injection of Platelet Rich Plasma and Hyaluronic Acid in Early Knee Osteoarthritis – Case Series
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