Validity of f-test in a randomized block design with missing data

In this paper the first two moments of the test criterion (Treat. S.S.)/(Treat.S.S. + Error S.S.) have been derived assuming that one observation corresponding to the first plot of the first block which is under treatment ‘m’ (say), is missing in a randomized block design with ‘V’ treatments and ‘r’ blocks. To keep the analysis simple the case of one missing observation has been considered. It is concluded that in general the design is not unbiased in YATES (1951) sense and the usual F-test is satisfactory iff /(vr - r - 1)=(S - S₁)/(v - 1) (r-1), the block errors are homogeneous and (vr - r - 1) is large. The analysis of three unifornity trial data indicates that the first condition is the most important for the F-test to be satisfactory. However, if one observation is missing at random from some plot of some block, the F-test is unbiased. If the block errors are homogeneous and (vr - r - 1) GT96, the F-test also provides a good approximation to the corresponding randomization test in this case.     

Visual arrestin modulates gene expression in the retinal pigment epithelium: Implications for homeostasis in the retina

The retinal pigment epithelium (RPE) is essential for maintaining retinal homeostasis by removing and recycling photoreceptor outer segment (POS) in membranes. It also produces and secretes growth factors involved in retinal homeostasis. Arrestin 1 (ARR1) is specifically expressed in photoreceptors (PRs) and a vital molecule for keeping visual cycle between PRs and RPE. In the present study, we showed the expression of ARR1 was decreased by form-deprivation (FD) in retina of rat. The ARR1 was detected in the RPE of the controls but not in the RPE of FD, which indicates RPE phagocytes POS containing ARR1. Furthermore, we overexpressed ARR1 in cultured human RPE and revealed the ARR1 upregulates bFGF expression and downregulates TGF-β1, -β2 and bone morphogenetic protein-2 (BMP-2). The upregulation of bFGF by ARR1 directly works for PR survival and the downregulation of TGF-βs by ARR1 inhibits epithelial mesenchymal transition (EMT) of RPE, which is the underlying mechanism of keeping retinal homeostasis. Our results also indicate the regulation of ARR1 expression in RPE might become a novel therapeutic option for various ocular diseases.     

Synthetic polymers as xeno-free materials for stabilizing basic fibroblast growth factor in human mesenchymal stem cell cultures

Series of sulfonated polymers were evaluated as additives in cell culture media. Some of the compounds, such as sulfated polyvinyl alcohol (PVA), prevented denaturation and loss of basic fibroblast growth factor during cell culture and enhanced human mesenchymal stem cell proliferation. These compounds are xeno-free alternatives of heparin, an animal-derived sulfated saccharide, often used as an additive. To the best our knowledge, this study is the first to show that chemically defined synthetic chemicals, such as sulfated polyvinyl alcohol, can be used for this purpose.