Tissue engineering of a bioartificial renal tubule

Development of a bioartificial renal tubule with a confluent monolayer of renal epithelial cells supported on a permeable synthetic surface may be the first step to further optimization of renal substitution therapy currently used with hemodialysis or hemofiltration. Madin-Darby canine kidney cells, a permanent renal epithelial cell line, were seeded into the lumen of single hollow fibers. Functional confluence of the cells was demonstrated by the recovery of intraluminally perfused 14C-inulin that averaged >98.9% in the cell lined units vs <7.4% in the control noncell hollow fibers during identical pressure and flow conditions. The baseline absolute fluid transport rate averaged 1.4+/-0.4 microl/30 min. To test the dependency of fluid flux with oncotic and osmotic pressure differences across the bioartificial tubule, albumin was added to the extracapillary space, followed by the addition of ouabain, an inhibitor of Na+K+ adenosine triphosphatase, the enzyme responsible for active transport across the renal epithelium. Addition of albumin resulted in a significant increase in volume transport to 4.5+/-1.0 microl/30 min. Addition of ouabain inhibited transport back to baseline levels of 2.1+/-0.4 microl/30 min. These results are the first demonstration that renal epithelial cells have been grown successfully as a confluent monolayer along a hollow fiber, and exhibit functional transport capabilities. The next steps in constructing a bioartificial renal tubule successfully are to develop a multi-fiber bioreactor with primary renal proximal tubule cells that maintain not only transport properties but also differentiated metabolic and endocrine functions, including glucose and ammonia production, and the conversion of vitamin D3 to a more active derivative. A renal tubule device may add critical renal functional components not currently substituted for, thereby improving the treatment regimens for patients with acute and chronic renal failure.

Had enough of bitcoins? If it is time to change the apparel of crypto trading, shift to altcoins. Altcoin is an abbreviated term for alternate coin. Yes, altcoins were released as alternative cryptocurrencies in place of bitcoins, following the tremendous success of the latter, for various reasons. Some examples of these alternative peer-to-peer digital currencies are Litecoin, Peercoin, Zetacoin, Dogecoin, Feathercoin, HireMatch, Komodo etc.

Some similarities

Altcoins share many similarities with the ruling Bitcoins such as:

  • The processing and running software backbone
  • Mining process for release and creation
  • Utilities in the online market like transactions and trading
  • Availability of automatic trading robots like Crypto Wealth and wallets

More differences

 Altcoins are numerous, different from each other in many features, functions, and purpose. Programming language: The programming languages used for the construction of algorithm, for trading, mining and transactions may be different, sometimes in the basic framework or sometimes in the versions. Usually, altcoins are supported by versatile languages as they are supposed to have more utility than Bitcoins when using as an alternative. External applications can be easily added on to these programs without altering the order in detail.

Transaction speed: the returns given by coins depend a lot on the speed with which they support transactions. When you are carrying out a trade, with many competitors eyeing on the same result, the fastest wins the race. While some altcoins are touted as faster than bitcoins, the rest are yet to pick up.

Coin Distribution Method: The availability and release of coins vary from type to type and region to region. For example, certain high-performing coins like LiteCoin which are high in demand are released following stringent mining processes while some others are distributed to all the citizens in a particular jurisdiction.

Proof-work-mining algorithms: There are some altcoins which do not require proof-of-work for mining, whereas for those which have this as compulsory have different methods of approach, slots for furnishing the proof of the stakes you earned and the rewards.

Specificity: While bitcoins are created majorly for trading and carrying out transactions, some altcoins are created for uses other than that related to money, such as for data storage locations, storing the registry of domain names, conversions etc.

Privacy: Altcoins are also designed for increasing privacy in cryptocurrency transactions. When a particular blockchain releases number of altcoins in a transaction, it means you have to overcome number of security zones.

PMID: 9617948
[Indexed for MEDLINE]