Antiviral therapy in neonatal cholestatic cytomegalovirus hepatitis

BACKGROUND: Neonatal hepatitis refers to a heterogeneous group of disorders, caused by many factors including cytomegalovirus infection, revealing similar morphologic changes in the liver of an infant less than 3 months of age. Approximately 40% of cholestasis in infants is due to neonatal hepatitis. It may cause latent or acute cholestatic or chronic hepatitis, including cirrhosis in immunocompetant infant. METHODS: Twelve infants diagnosed with neonatal cytomegalovirus hepatitis in the last one year were included in the study. Group 1 consisted of seven babies treated with ganciclovir for 21 days. Group 2 included five cases who did not receive antiviral treatment. Physical examination, biochemical, serologic and virologic tests were done for both groups at the time of diagnosis and in the third month. RESULTS: Initial levels of total bilirubin, aminotransferases, gamma glutamyl transpeptidase, and alkaline phosphatase revealed a significant decrease after the treatment in Group 1 (p < 0.05) when compared with Group 2. This study revealed that ganciclovir treatment is a safe and effective in cases with cholestatic hepatitis. Similarly, all the patients in the treatment group had evidence of improvement serologically and virologically, while the comparison group did not reveal any significant change(p < 0.01). CONCLUSION: The clinical spectrum of perinatal infection varies from an asymptomatic infection or a mild disease to a severe systemic involvement, including central nervous system. The treatment in the early period of infection improved serologic markers and cholestatic parameters significantly. Further studies will lead us to clarify the efficacy of ganciclovir treatment in the early period of cytomegalovirus hepatitis, and the preventive role of anti-viral therapy on progressive liver disease due to cholestasis and hepatitis in neonatal cytomegalovirus infection

Volatility transmission between Islamic and conventional equity markets : evidence from causality-in-variance test

This study examines whether a volatility/risk transmission exists between the Dow Jones Islamic stock and three conventional stock markets for the United States, Europe and Asia during the pre- and the in- and post-2008 crisis periods. It also explores the volatility spillover dynamics between those markets and US Monetary policy, oil prices, global financial risk and uncertainty factors. The recently developed Hafner and Herwartz (2006)’s causality-in-variance test provides evidence of risk transfers between these seemingly different equity markets, indicating a contagion between them during the full sample and the subperiods. The volatility structure of these markets is dominated by short-run volatility in the first period and by high long-run volatility in the second period. The volatility impulse response analysis indicates a similar volatility transmission pattern although it is characterized by a more volatile and short-lived structure in the second period. It also appears that the Islamic equity market responds to shocks from the risk factors and not from the oil price and the US economic policy uncertainty index during both periods.http://www.tandfonline.com/loi/raec202016-10-31hb201

Volatility spillovers and cross-hedging between gold, oil and equities: Evidence from the Gulf Cooperation Council countries

The paper examines the return and volatility spillovers between crude oil, gold and equities, and investigates the usefulness of the two commodities in hedging equity portfolios. Using daily data from January 20043 to May 2016 for the Gulf Cooperation Council countries, a DCC-GARCH model is used to estimate dynamic correlations and hedge ratios. We find significant spillovers from oil to equities, highlighting the heavy dependence of the local economies on oil. Moreover, the spillovers of gold on the stock markets are insignificant, suggesting that gold price fluctuations do not necessarily influence equity investment decisions. In the opposite direction, we find that equities do not exert significant influence on the two commodities, which we attribute to the relatively small capitalisation of the exchanges. Our results reveal low dynamic correlations and hedge ratios, with a few spikes during crises, indicating that oil and gold are cheap hedges for stocks, albeit not good ones, while they could be considered as weak safe havens, but at a considerable cost

Forecasting Realized Volatility of Agricultural Commodities

We forecast the realized and median realized volatility of agricultural commodities using variants of the Heterogeneous AutoRegressive (HAR) model. We obtain tick-by-tick data for five widely traded agricultural commodities (Corn, Rough Rice, Soybeans, Sugar, and Wheat) from the CME/ICE. Real out-of-sample forecasts are produced for 1- up to 66-days ahead. Our in-sample analysis shows that the variants of the HAR model which decompose volatility measures into their continuous path and jump components and incorporate leverage effects offer better fitting in the predictive regressions. However, we convincingly demonstrate that such HAR extensions do not offer any superior predictive ability in the out-of-sample results, since none of these extensions produce significantly better forecasts compared to the simple HAR model. Our results remain robust even when we evaluate them in a Value-at-Risk framework. Thus, there is no benefit by adding more complexity, related to volatility decomposition or relative transformations of volatility, in the forecasting models

Do Islamic indices provide diversification to bitcoin? A time-varying copulas and value at risk application

This is an accepted manuscript of an article published by Elsevier in Pacific-Basin Finance Journal on 08/04/2020, available online: https://doi.org/10.1016/j.pacfin.2020.101326 The accepted version of the publication may differ from the final published version.© 2020 The emergence of new asset classes offers avenues to international investment community however understanding relationship between any two assets in a single portfolio is important. We investigate the risk dependence between daily Bitcoin and major Islamic equity markets spanning over from July 2010 to March 2018. We start by examining long memory properties of Bitcoin and sampled Islamic indices and report significant results. The residuals from fractionally integrated models are then used in bivariate time invariant and time varying copulas to investigate dependence structure. Among all Islamic indices, DJIUK, DJIJP and DJICA exhibit time varying dependence with Bitcoin. In addition, we apply VaR, CoVaR and ΔCoVaR as risk measure to examine spillover between Bitcoin and Islamic equity markets. VaR of Bitcoin exceeds from VaR of Islamic indices and CoVaR of both Islamic and Bitcoin exceeds their respective VaR, suggesting presence of risk spillover between each other. Our results also report asymmetry between downside and upside ΔCoVaR suggesting implications for investors with different risk preferences. Finally, the diversification benefits indicate that Islamic equity market serves as an effective hedge in a portfolio along with Bitcoin.Accepted versio

causality

The increasing co-movements between the world oil and agricultural commodity prices have renewed interest in determining price transmission from oil prices to those of agricultural commodities. This study extends the literature on the oil-agricultural commodity prices nexus, which particularly concentrates on nonlinear causal relationships between the world oil and three key agricultural commodity prices (corn, soybeans, and wheat). To this end, the linear causality approach of Toda-Yamamoto and the nonparametric causality method of Diks-Panchenko are applied to the weekly data spanning from 1994 to 2010. The linear causality analysis indicates that the oil prices and the agricultural commodity prices do not influence each other, which supports evidence on the neutrality hypothesis. In contrast, the nonlinear causality analysis shows that: (i) there are nonlinear feedbacks between the oil and the agricultural prices, and (ii) there is a persistent unidirectional nonlinear causality running from the oil prices to the corn and to the soybeans prices. The findings from the nonlinear causality analysis therefore provide clues for better understanding the recent dynamics of the agricultural commodity prices and some policy implications for policy makers, farmers, and global investors. This study also suggests the directions for future studies. (C) 2011 Elsevier Ltd. All rights reserved

cointegration analysis

The purpose of this article is to investigate the impact of the exchange rate volatility on Turkey's export. To this end, the panel cointegration analysis is applied to the data from Turkey's top 20 export industries to major 20 trading partners for the period 1980-2009. Special attention is paid to test for whether employment of country-level trade data instead of industry-level data is subject to the aggregation bias problem in the estimation of long-run cointegration parameters. The results indicate that employing country-level trade data suffers from the aggregation bias in estimating the cointegration parameters for the level of exchange rate and for the exchange rate volatility. The findings imply that (i) the impact of the exchange rate volatility on Turkish exports differs across industries, (ii) Turkey benefits from the depreciation of Turkish lira, and(iii) the foreign income plays a key role in determining the Turkish industry-level exports. The findings increase our insights to explain therecent dynamics of Turkish exports and provide some policy implications

Trends in international commodity prices: Panel unit root analysis

The purpose of this paper is to examine the behavior of international commodity prices within the context of the Prebisch-Singer hypothesis. To this end, I utilize a panel unit root approach which is able to account for multiple structural breaks and cross-section dependency. The unit root analysis for 24 international commodity prices during the period 1900-2003 shows evidence in favor of the trend stationary process in the commodity prices. The results thereby imply that shocks to commodity prices are temporary in nature and tend to be corrected over time. The estimation of the trend stationary models indicates that the Prebisch-Singer hypothesis is not a universal phenomenon. (C) 2014 Elsevier Inc. All rights reserved

World oil and agricultural commodity prices: Evidence from nonlinear causality

The increasing co-movements between the world oil and agricultural commodity prices have renewed interest in determining price transmission from oil prices to those of agricultural commodities. This study extends the literature on the oil-agricultural commodity prices nexus, which particularly concentrates on nonlinear causal relationships between the world oil and three key agricultural commodity prices (corn, soybeans, and wheat). To this end, the linear causality approach of Toda-Yamamoto and the nonparametric causality method of Diks-Panchenko are applied to the weekly data spanning from 1994 to 2010. The linear causality analysis indicates that the oil prices and the agricultural commodity prices do not influence each other, which supports evidence on the neutrality hypothesis. In contrast, the nonlinear causality analysis shows that: (i) there are nonlinear feedbacks between the oil and the agricultural prices, and (ii) there is a persistent unidirectional nonlinear causality running from the oil prices to the corn and to the soybeans prices. The findings from the nonlinear causality analysis therefore provide clues for better understanding the recent dynamics of the agricultural commodity prices and some policy implications for policy makers, farmers, and global investors. This study also suggests the directions for future studies.Oil prices Agricultural commodity prices Linear and nonlinear Granger causality