Tet-mediated imprinting erasure in H19 locus following reprogramming of spermatogonial stem cells to induced pluripotent stem cells.

Selective methylation of CpG islands at imprinting control regions (ICR) determines the monoparental expression of a subset of genes. Currently, it is unclear whether artificial reprogramming induced by the expression of Yamanaka factors disrupts these marks and whether cell type of origin affects the dynamics of reprogramming. In this study, spermatogonial stem cells (SSC) that harbor paternalized imprinting marks, and fibroblasts were reprogrammed to iPSC (SSCiPSC and fiPSC). The SSCiPSC were able to form teratomas and generated chimeras with a higher skin chimerism than those derived from fiPSC. RNA-seq revealed extensive reprogramming at the transcriptional level with 8124 genes differentially expressed between SSC and SSCiPSC and only 490 between SSCiPSC and fiPSC. Likewise, reprogramming of SSC affected 26 of 41 imprinting gene clusters known in the mouse genome. A closer look at H19 ICR revealed complete erasure in SSCiPSC in contrast to fiPSC. Imprinting erasure in SSCiPSC was maintained even after in vivo differentiation into teratomas. Reprogramming of SSC from Tet1 and Tet2 double knockout mice however lacked demethylation of H19 ICR. These results suggest that imprinting erasure during reprogramming depends on the epigenetic landscape of the precursor cell and is mediated by TETs at the H19 locus.

Prime vendor purchasing of pharmaceuticals in the Veterans Affairs health care system.

The development of a prime vendor system of pharmaceutical procurement and distribution in the Department of Veterans Affairs (VA) is described. The traditional system of pharmaceutical procurement and distribution in the VA required large stockpiles of the pharmaceuticals that had been needed the previous year, a system that was inefficient and full of hidden markups and other unnecessary fees. In late 1991, the VA began a pilot test of a prime vendor system, in which three wholesalers were selected to provide pharmaceuticals to 33 VA medical centers. Under the new system, pharmacies placed orders electronically, directly with the prime vendor, and payments were taken from funds obligated in advance. The benefits of the new system included reduced costs, faster turnaround of orders, higher fill rates, and higher satisfaction among users. In 1994, the VA ceased operation of its traditional depot system for pharmaceuticals. The implementation of a prime vendor procurement system for pharmaceuticals within the VA improved system responsiveness, increased satisfaction of system users, and reduced expenses.

Pulmonary indoleamine 2,3-dioxygenase activity and its significance in the response of rats, mice, and rabbits to oxidative stress.

The physiological significance of the enzyme indoleamine 2,3,-dioxygenase (IDO) (EC 1.13.11.17), which consumes superoxide anion (O2-), is not known. Since this enzyme is found in high concentrations in lung tissue, we examined the possibility that IDO may protect against chemically induced oxidative stress in the lung. The induction of IDO by bacterial lipopolysaccharide (LPS) was found to be 20-fold in the mouse and 4-fold in the rat, but did not confer protection against paraquat-induced pulmonary toxicity. Moreover, paraquat, when dosed to rats or mice, did not induce pulmonary IDO activity. An elevation in the intracellular O2- concentration was sought by incubating lung slices with 5 mM diethyldithiocarbamate (DDTC) (to inhibit SOD), paraquat (10(-4) M), or methylene blue (10(-4) M) or under an atmosphere of 100% oxygen. These attempts did not enhance the IDO activity in lung slices prepared from control or LPS-treated rats and mice. There was also no evidence that the uptake of an IDO substrate, tryptophan, was limiting for IDO activity in rat and mouse lung slices. We have concluded in the case of rats and mice that the pulmonary IDO activity, even following induction, is too low for O2- to be the rate-limiting factor. For this reason IDO cannot act as a protective enzyme by scavenging O2- in the lung of these species. However, in the rabbit, a species comparatively resistant to paraquat- and oxygen-induced lung damage, pulmonary IDO activity is 170 times that of rats or mice. IDO activity in rabbit lung slices was increased 4-fold by incubation with 5 mM DDTC and 10-fold by incubation with methylene blue (10(-4) M). However, paraquat (10(-4) M and oxygen (100% atmosphere) were able to enhance IDO activity (5-fold) only when SOD had previously been inhibited. We have concluded that in the rabbit lung IDO is able to scavenge O2- and therefore has the potential to act as a protective enzyme in this species.