Publications by authors named "Alexander Kritikos"

Article Synopsis
  • Vertebrate sexual dimorphism, traditionally linked to the type of gonads (testes or ovaries) and their hormone production, is now shown to also be influenced by sex chromosomes (XX or XY).
  • Using the Four-Core Genotypes (FCG) mouse model, the study reveals that both gonads and sex chromosomes affect the musculoskeletal system's development, with notable differences becoming more pronounced in older mice.
  • Findings indicate that while gonadal sex plays a significant role in musculoskeletal traits, sex chromosomes contribute meaningfully to differences in body composition and bone strength, particularly as the mice mature.
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Financing entrepreneurship spurs innovation and economic growth. Digital financial platforms that crowdfund equity for entrepreneurs have emerged globally, yet they remain poorly understood. We model equity crowdfunding in terms of the relationship between the number of investors and the amount of money raised per pitch.

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α-Synuclein (α-Syn) is implicated in Parkinson's disease (PD), a neuromotor disorder with prominent visual symptoms. The underlying cause of motor dysfunction has been studied extensively, and is attributed to the death of dopaminergic neurons mediated in part by intracellular aggregation of α-Syn. The cause of visual symptoms, however, is less clear.

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The self-employed faced strong income losses during the Covid-19 pandemic. Many governments introduced programs to financially support the self-employed during the pandemic, including Germany. The German Ministry for Economic Affairs announced a €50bn emergency-aid program in March 2020, offering one-off lump-sum payments of up to €15,000 to those facing substantial revenue declines.

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We use the prolonged Greek crisis as a case study to understand how a lasting economic shock affects the innovation strategies of firms in economies with moderate innovation activities. Adopting the 3-stage CDM model, we explore the link between R&D, innovation, and productivity for different size groups of Greek manufacturing firms during the prolonged crisis. At the first stage, we find that the continuation of the crisis is harmful for the R&D engagement of smaller firms while it increased the willingness for R&D activities among the larger ones.

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The existential threat to small businesses, based on their crucial role in the economy, is behind the plethora of scholarly studies in 2020, the first year of the COVID-19 pandemic. Examining the 15 contributions of the special issue on the "Economic effects of the COVID-19 pandemic on entrepreneurship and small businesses," the paper comprises four parts: a systematic review of the literature on the effect on entrepreneurship and small businesses; a discussion of four literature strands based on this review; an overview of the contributions in this special issue; and some ideas for post-pandemic economic research.

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Recently, we reported β-cleavage of the prion protein (PrP) in human ocular tissues. Here, we explored whether this is unique to the human eye, and its functional implications. A comparison of the cleavage pattern of PrP in human ocular tissues with common nocturnal and diurnal animals revealed mainly β-cleavage in humans, and mostly full-length PrP in animal retinas.

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To evaluate the role of iron in sodium iodate (NaIO)-induced model of age-related macular degeneration (AMD) in ARPE-19 cells in-vitro and in mouse models in-vivo. ARPE-19 cells, a human retinal pigment epithelial cell line, was exposed to 10 mM NaIO for 24 h, and the expression and localization of major iron modulating proteins was evaluated by Western blotting (WB) and immunostaining. Synthesis and maturation of cathepsin-D (cat-D), a lysosomal enzyme, was evaluated by quantitative reverse-transcriptase polymerase chain reaction (RT-qPCR) and WB, respectively.

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Accumulation of redox-active iron in human sporadic Creutzfeldt-Jakob disease (sCJD) brain tissue and scrapie-infected mouse brains has been demonstrated previously. Here, we explored whether upregulation of local hepcidin secreted within the brain is the underlying cause of iron accumulation and associated toxicity. Using scrapie-infected mouse brains, we demonstrate transcriptional upregulation of hepcidin relative to controls.

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Background: Accumulation of iron is a consistent feature of Alzheimer's disease (AD) brains. The underlying cause, however, remains debatable.

Objective: To explore whether local hepcidin synthesized by brain cells contributes to iron accumulation in AD brains.

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We investigate how the economic consequences of the pandemic and the government-mandated measures to contain its spread affect the self-employed - particularly women - in Germany. For our analysis, we use representative, real-time survey data in which respondents were asked about their situation during the COVID-19 pandemic. Our findings indicate that among the self-employed, who generally face a higher likelihood of income losses due to COVID-19 than employees, women are about one-third more likely to experience income losses than their male counterparts.

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Age-related macular degeneration (AMD) and glaucoma are degenerative conditions of the retina and a significant cause of irreversible blindness in developed countries. Alzheimer's disease (AD), the most common dementia of the elderly, is often associated with AMD and glaucoma. The cardinal features of AD include extracellular accumulation of amyloid β (Aβ) and intracellular deposits of hyper-phosphorylated tau (p-tau).

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Purpose: Elevated levels of transforming-growth-factor (TGF)-β2 in the trabecular meshwork (TM) and aqueous humor are associated with primary open-angle glaucoma (POAG). The underlying mechanism includes alteration of extracellular matrix homeostasis through Smad-dependent and independent signaling. Smad4, an essential co-Smad, upregulates hepcidin, the master regulator of iron homeostasis.

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Purpose: The avascular cornea, trabecular meshwork (TM), and lens obtain iron, an essential biometal, from the aqueous humor (AH). The mechanism by which this exchange is regulated, however, is unclear. Recently we reported that non-pigmented ciliary epithelial cells express ferroportin (Fpn) (Ashok, 2018b), an iron export protein modulated by hepcidin, the master regulator of iron homeostasis secreted mainly by the liver.

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