Leigh syndrome (LS) is a rare, inherited neurometabolic disorder that presents with bilateral brain lesions caused by defects in the mitochondrial respiratory chain and associated nuclear-encoded proteins. We generated human induced pluripotent stem cells (iPSCs) from three LS patient-derived fibroblast lines. Using whole-exome and mitochondrial sequencing, we identified unreported mutations in pyruvate dehydrogenase (GM0372, PDH; GM13411, MT-ATP6/PDH) and dihydrolipoyl dehydrogenase (GM01503, DLD). These LS patient-derived iPSC lines were viable and capable of differentiating into progenitor populations, but we identified several abnormalities in three-dimensional differentiation models of brain development. LS patient-derived cerebral organoids showed defects in neural epithelial bud generation, size and cortical architecture at 100 days. The double mutant MT-ATP6/PDH line produced organoid neural precursor cells with abnormal mitochondrial morphology, characterized by fragmentation and disorganization, and showed an increased generation of astrocytes. These studies aim to provide a comprehensive phenotypic characterization of available patient-derived cell lines that can be used to study Leigh syndrome.

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Environmental, social, and governance (ESG) scores play a pivotal role in the strategic design of firms. The literature has demonstrated the importance of sustainability issues in the financial performance of firms around the world. In particular, understanding the relationship between sustainability and the cost of capital is crucial for determining financial strategy and decision making. We identify an opportunity in the literature to analyze this relationship within Latin America (LatAm) firms. Thus, this study analyzes the relationship between ESG scores with the cost of capital of firms with headquarters in LatAm using a data set that includes 606 observations corresponding to information about 202 firms from 2017 to 2019. To conduct our analysis, two fixed effects panel data models were estimated. We model this relationship by taking ESG scores and each of its ESG Pillar scores—i.e., Environmental, Social, and Governance pillar scores—as independent variables and analyzing how they affect the cost of capital. According to the results, there is an inverse effect relationship between ESG scores and the cost of capital. Additionally, we did not find a relationship between the Social Pillar score and the Environmental Pillar score with the cost of capital. By contrast, the Governance Pillar score shows a negative relationship with the cost of capital. This indicates that the increase in transparency about internal processes and governance entities can be an essential driver of value creation for firms and higher financing confidence in LatAm firms. This study represents a breakthrough in explaining the impact of ESG scores on the cost of capital in LatAm. Ultimately, the current study presents the potential for further research in this field.

SummaryLeigh syndrome (LS) is a rare, inherited neuro-metabolic disorder that presents with bilateral brain lesions. This disease is caused by defects in the mitochondrial respiratory chain and associated nuclear-encoded proteins. We generated induced pluripotent stem cells (iPSCs) from three widely available LS fibroblast lines and identified, through whole exome and mitochondrial sequencing, unreported mutations in pyruvate dehydrogenase (GM0372, PDH; GM13411, MT-ATP6/PDH) and dihydrolipoyl dehydrogenase (GM01503, DLD). LS derived cell lines were viable and able to differentiate into key progenitor populations, but we identified several abnormalities in three-dimensional differentiation models of brain development. The DLD-mutant line showed decreased neural rosette (NR) formation, and there were differences in NR lumen area in all three LS lines compared to control. LS-derived cerebral organoids showed defects in neural epithelial bud generation and reduced size when grown for 100 days. Loss of cortical architecture and markers were detected at days 30 and 100. The MT-ATP6/PDH line produced organoid neural progenitor cells with an abnormal mitochondrial morphology characterized by fragmentation and disorganization, and demonstrated increased generation of astrocytes. These studies aim to provide a comprehensive phenotypic characterization of available patient-derived cell lines that could be used as LS model systems.

This paper investigates how systematic risk varies over the lifecycle of the firm. If market equity beta is determined by firm characteristics as the literature on the determinants of systematic risk holds, and if those characteristics change over the lifecycle of the firm following a definite pattern as firm lifecycle theory suggests, then market equity beta should change over the lifecycle of the firm following a predictable pattern. Our findings indicate that holding other determinants of beta constant, the coefficient of systematic risk tends to fall in magnitude following a nonlinear pattern as firm age increases. In addition, we find that the volatility of market equity beta also tends to fall over the lifecycle of the firm. We argue that our main variable of concern, that is, firm age, proxies for variables that have hitherto been omitted in the literature on the determinants of systematic risk. In particular, we maintain that firm age proxies for the mispricing propensity that young firms lose as they mature. This research is useful for both practitioners and researchers in that it may suggest ways to adjust empirical estimates of systematic risk. In addition, our results are important for research on beta forecasting as they show that the length of the stationary interval of betas is shorter for young companies, and therefore it is necessary to take into account this time varying characteristic in the estimation process in order to improve the beta forecasting.

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This paper investigates how of systematic risk varies over the lifecycle of the firm. If market equity beta is determined by firm characteristics as the literature on the determinants of systematic risk holds, and if those characteristics change over the lifecycle of the firm following a definite pattern as firm lifecycle theory suggests, then market equity beta should change over the lifecycle of the firm following a predictable pattern. Our findings indicate that, holding other determinants of beta constant, the coefficient of systematic risk tends to fall in magnitude following a nonlinear pattern as firm age increases. In addition, we find that the volatility of market equity beta also tends to fall over the lifecycle of the firm. We argue that our main variable of concern, i.e. firm age, proxies for variables that have hitherto been omitted in the literature on the determinants of systematic risk. In particular, we maintain that firm age may proxy for the positive reputation that firms acquire over time with shareholders. This research is useful for both practitioners and researchers in that it may suggest ways to adjust empirical estimates of systematic risk. In addition, our results are important for research on beta forecasting as they show that the length of the stationary interval of betas is shorter for young companies, so that beta forecasting may be less accurate for firms in the early stages of their lifecycle compared to beta forecasting for mature firms.KEYWORDS: Systematic risk, firm lifecycle, intrinsic business risk, financial leverage, operating risk. Quite apart from this regression tendency, it is reasonable to suppose that betas do change over time in systematic ways in response to certain changes in the structure of companies (Blume 1975, p. 785, n. 1).

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