Transport of prion protein across the blood-brain barrier.

The cellular form of the prion protein (PrP(c)) is necessary for the development of prion diseases and is a highly conserved protein that may play a role in neuroprotection. PrP(c) is found in both blood and cerebrospinal fluid and is likely produced by both peripheral tissues and the central nervous system (CNS). Exchange of PrP(c) between the brain and peripheral tissues could have important pathophysiologic and therapeutic implications, but it is unknown whether PrP(c) can cross the blood-brain barrier (BBB). Here, we found that radioactively labeled PrP(c) crossed the BBB in both the brain-to-blood and blood-to-brain directions. PrP(c) was enzymatically stable in blood and in brain, was cleared by liver and kidney, and was sequestered by spleen and the cervical lymph nodes. Circulating PrP(c) entered all regions of the CNS, but uptake by the lumbar and cervical spinal cord, hypothalamus, thalamus, and striatum was particularly high. These results show that PrP(c) has bidirectional, saturable transport across the BBB and selectively targets some CNS regions. Such transport may play a role in PrP(c) function and prion replication.

Viability of enteric bacterial pathogens in transport media

Bacterial pathogens such as enterotoxigenic Escherichia coli, Salmonella, and Campylobacter spp. are associated with up to 80% of diarrheal illness to travelers from developed countries to developing countries. In order to study acute gastrointestinal diseases, researchers from developed countries such as the United States rely on transporting clinical specimens from the developing countries to laboratories in the U.S. in transport media systems. There are few commercially available transport media systems cited in the literature or designated by transport system manufacturers for the transport of enteric bacteria. Therefore a laboratory-based study was conducted to assess three commercial available transport media systems, two gel swabs and one liquid vial, to determine the most appropriate for the maintenance and recovery of common enteric bacterial pathogens. A total of 13 bacterial enteropathogens were recovered from 25°C and 4°C storage temperatures at time points up to 21 days. The results demonstrated that the gel swab and liquid vial transport systems performed similarly for all isolates at both temperatures. All three transport media systems struggled to maintain the isolates at recoverable concentrations when stored at 4°C and it is recommended that isolates be stored at 25°C in transport media systems. Lastly, swab transport systems are recommend for transport since they are small and easy to pack, resist leakage, and are less expensive than similarly performing liquid vial transport media systems.^