Short report: phylogenetically distinct hepatitis E viruses in Pakistan.

Hepatitis E, which is enterically transmitted, is the most common cause of acute hepatitis in much of Asia. Phylogenetic analysis of several isolates of hepatitis E virus (HEV) from Asia suggests that transmission of this virus is geographically restricted. In Sarghoda, Pakistan, HEV Sar-55 was isolated from a 1987 outbreak. It belongs to the Central-Asian cluster of the Asian sub-genotype. We now report the complete sequence of a second Pakistan HEV from a 1988 outbreak in Abbottabad. The Abbottabad nucleotide sequence was compared with 15 other complete HEV sequences using statistical methods of phylogenetic analysis. The analysis showed that Abbottabad HEV belongs to the South Asia cluster of the Asian sub-genotype. The sequence differences of the 2 Pakistan isolates recovered only one year apart suggest that HEV of 2 distinct origins circulate in Pakistan.

Protracted systemic changes in bone biology after segmented unloading in the rat.

To investigate whether the decreased bone formation observed in most experimental situations of disuse was caused by an increased inhibition by the bone microenvironment of osteoblast (OB) proliferation, we studied the inhibiting power on ROS 17/2.8 proliferation of the bone marrow extracellular fluid (IPEF) in loaded and unloaded bones of rats submitted to two situations of partial disuse: tail suspension (TS) for 3 days to 2 weeks and around the knee tenectomy (KT) for 2-10 weeks. Histomorphometric parameters and osteoblast precursors dynamics were studied in parallel. Bone volume was lost in the unloaded bones, but not in loaded bones, in both experimental situations. Bone formation was low at early times (7-14 days) in TS rats. However, in KT at later times (4-10 weeks), the osteoblastic index of the unloaded tibia was increased. IPEF was not increased in the unloaded bones 3-7 days after TS. It was decreased later in the course of unloading (after 2 weeks of TS and 2-10 weeks after KT). This decrease was observed in the loaded bones as well. Unexpectedly, we also found that the number of FCFUs was decreased in both loaded and unloaded limbs in TS and KT, and that the yield of cells obtained in primary culture from tibial metaphysis was decreased in both tibiae from KT animals. These data show that an increased IPEF does not play a role in the early inhibition of bone formation responsible for the loss of bone after unloading in the TS model. Its later decrease could be permissive for the increased osteoblastic index observed in the KT model. They also show that, contrary to the usual assumptions, bone biology is changed all over the skeleton after partial unloading, even if the changes result in bone loss in the unloaded bones only. Thus, as yet, unidentified systemic factors probably superimpose on the local factors that control bone volume.