Inhibition of Steady-State Intestinal Absorption of Long-Chain Triglyceride by Medium-Chain Triglyceride in the Unanesthetized Rat

A B s T R A C T Maximal steady-state intestinal absorption rates in unanesthetized rats for triolein, a long-chain triglyceride, and for trioctanoin, a medium-chain triglyceride, are known to differ. Both these lipids are hydrolyzed in the intestinal lumen but the products of hydrolysis are metabolized differently by the mucosal cell. Intraduodenal infusion of trioctanoin was found to reduce steady-state triolein absorption. Luminal lipolysis was shown not to be rate-controlling. High rates of trioctanoin infusion significantly lowered the pH of the luminal aqueous phase and altered the partition of oleic acid between aqueous and oil phases. Two possible mechanisms for the inhibition of triolein uptake are considered. In the intestinal lumen medium chain lipids might have lowered the activity of oleic acid monomers in the aqueous phase and reduced passive diffusion into mucosal cells. Alternatively, competition between long and medium chain fatty acids for some common receptor during transport into the intestinal mucosal cell may have occurred. Despite significant inhibition of triolein absorption by high levels of trioctanoin, the maximum number of calories absorbed from mixtures of triglycerides exceeded the maxima from either glyceride alone. The optimum proportion of triolein to trioctanoin in lipid infusion mixtures was about 3: 4 by weight and the optimum dosages about half maximal for each triglyceride, which represented a caloric intake of 4 kcal/rat per 2 hr. The absorption coefficient for this lipid mixture was about 90%. It is suggested that in patients who have a limited intestinal absorptive capacity dietary fat intake might be doubled with a caloric supplement of mediumchain triglycerides without increase in steatorrhea of long-chain fat. This work was published in part as an abstract (1)

Heavy quark energy loss in nuclear medium

Multiple scattering, modified fragmentation functions and radiative energy loss of a heavy quark propagating in a nuclear medium are investigated in perturbative QCD. Because of the quark mass dependence of the gluon formation time, the medium size dependence of heavy quark energy loss is found to change from a linear to a quadratic form when the initial energy and momentum scale are increased relative to the quark mass. The radiative energy loss is also significantly suppressed relative to a light quark due to the suppression of collinear gluon emission by a heavy quark

What Determines the Composition of International Bank Flows?

Several recent studies document that the extent to which banks transmit shocks across borders depends on the type of foreign activities these banks engage in. This paper proposes a model to explain the composition of banks' foreign activities, distinguishing between international interbank lending, intrabank lending, and cross-border lending to foreign firms. The model shows that the different activities are jointly determined and depend on the efficiencies of countries' banking sectors, differences in the return on loans across countries, and impediments to foreign bank operations. Specifically, the model predicts that international interbank lending increases and lending to foreign non banking firms declines when banks' barriers to entry rise, a hypothesis supported by German bank-level data. This result suggests that policies that restrict the operations of foreign banks in a country may move activity onto international interbank markets, with the potential to make domestic credit overall less resilient to financial distress