The effect of Eck and reverse Eck fistula in dogs with experimental diabetes mellitus

1. 1. Dogs with alloxan diabetes were subjected to Eck fistula. This procedure produced a marked increase in the amount of insulin necessary to control glycosuria. When the dogs were fasted, glycosuria disappeared, blood sugars fell toward normal, and the need for insulin was eliminated. 2. 2. Reverse Eck fistula was created in dogs with alloxan diabetes, and resulted in minor increases of doubtful significance in daily insulin requirement. When fasted, the blood sugar of these animals remained elevated and glycosuria continued. 3. 3. Nondiabetic dogs with Eck fistula all died of meat intoxication. Dogs with Eck fistula plus diabetes had no evidence of meat intoxication and in general were in better health than dogs with Eck fistula alone. 4. 4. Possible mechanisms of the role of Eck fistula in the alteration of the diabetic state are discussed. © 1959

The reverse portacaval shunt

A technique has been described in which all the venous drainage of the deep femoral system is diverted through the hepatic bed by means of a reverse Eck fistula and systematic division of collaterals from the inferior vena cava and iliac veins. The use of this technique in the study of liver metabolism is proposed. Employment of simple reverse Eck fistula is suggested in clinical situations in which there is subdiaphragmatic destruction of the inferior vena cava. © 1959

Prophylactic tracheostomy in aged and poor risk general surgical patients

The most common postoperative complications are those involving respiration, and they are especially dangerous to patients classified as poor risks because of age or other handicaps. Among the 11 patients whose histories are given, some who were nearly moribund from respiratory difficulties were saved by tracheostomy; others made good recoveries from major surgery under conditions that would have been hopeless without the help afforded by prophylactic tracheostomy. If this possibility is foreseen, an orderly procedure can be carried out in the operating room instead of desperate measures on the ward. Scrupulous care of the tracheostomy is essential; this includes aseptic precautions, humidification of the inhaled air or oxygen, and the systematic but gentle use of suction to aspirate accumulating mucus. © 1959, American Medical Association. All rights reserved

Effect in dogs of various portal vein shunts on response to insulin

Surgical alterations of portal drainage patterns were made in dogs in order to determine the effect of redistribution of endogenous and injected insulin. With an Eck fistula, progressive diminution of hypoglycemic response to insulin was noted. With a reverse Eck fistula, the fall in venous blood sugar was comparable whether injection was given via the portal system or systemically. With portacaval transposition, in which the pancreatic drainage is diverted from the liver, no alterations in general health, fasting blood sugars, or insulin response were noted. The results are discussed in relation to recent concepts in which insulin is thought to regulate or be regulated by the liver

Testing the paradox of enrichment along a land use gradient in a multitrophic aboveground and belowground community

In the light of ongoing land use changes, it is important to understand how multitrophic communities perform at different land use intensities. The paradox of enrichment predicts that fertilization leads to destabilization and extinction of predator-prey systems. We tested this prediction for a land use intensity gradient from natural to highly fertilized agricultural ecosystems. We included multiple aboveground and belowground trophic levels and land use-dependent searching efficiencies of insects. To overcome logistic constraints of field experiments, we used a successfully validated simulation model to investigate plant responses to removal of herbivores and their enemies. Consistent with our predictions, instability measured by herbivore-induced plant mortality increased with increasing land use intensity. Simultaneously, the balance between herbivores and natural enemies turned increasingly towards herbivore dominance and natural enemy failure. Under natural conditions, there were more frequently significant effects of belowground herbivores and their natural enemies on plant performance, whereas there were more aboveground effects in agroecosystems. This result was partly due to the “boom-bust” behavior of the shoot herbivore population. Plant responses to herbivore or natural enemy removal were much more abrupt than the imposed smooth land use intensity gradient. This may be due to the presence of multiple trophic levels aboveground and belowground. Our model suggests that destabilization and extinction are more likely to occur in agroecosystems than in natural communities, but the shape of the relationship is nonlinear under the influence of multiple trophic interactions.

Unwinding of a cholesteric liquid crystal and bidirectional surface anchoring

We examine the influence of bidirectional anchoring on the unwinding of a planar cholesteric liquid crystal induced by the application of a magnetic field. We consider a liquid crystal layer confined between two plates with the helical axis perpendicular to the substrates. We fixed the director twist on one boundary and allow for bidirectional anchoring on the other by introducing a high-order surface potential. By minimizing the total free energy for the system, we investigate the untwisting of the cholesteric helix as the liquid crystal attempts to align with the magnetic field. The transitions between metastable states occur as a series of pitchjumps as the helix expels quarter or half-turn twists, depending on the relative sizes of the strength of the surface potential and the bidirectional anchoring. We show that secondary easy axis directions can play a significant role in the unwinding of the cholesteric in its transition towards a nematic, especially when the surface anchoring strength is large