Portal vein insulin response of glucose intolerant Yucatan miniature swine to common secretogogues

A group of glucose intolerant miniature swine exhibiting an impaired portal vein insulin response to an IVGTT were examined with respect to their portal vein insulin response to the secretogogues: isoproterenol, arginine and leucine. Equivalent insulin responses to isoproterenol and leucine were noted on the part of the glucose intolerant animals when compared to control subjects. An impaired portal vein insulin response was evident during an infusion of 0.5 g/kg arginine and again when a pulse injection of .25 g/kg glucose was administered in the presence of isoproterenol (.05 microgram/kg . min). The close agreement of these results with those reported for human diabetics suggests that a similar pancreatic defect, most probably associated with the glucoreceptor, is present in this group of glucose intolerant miniature swine.     

A quantitative study of the summer phytoplankton in four Central North Carolina ponds

Summary The phytoplankton of four ponds in the lower Piedmont and upper Coastal Plain of North Carolina was studied to find a possible correlation between bound phosphorus plankton numbers. No correlation was apparent therefore this paper reports a detailed study in relation to other habitat factors.The ponds are all shallow (2 m.). The Piedmont ponds are high in colloidal clay while the Coastal Plain ponds are much lower. The pH ranged around 7.0 except for one Coastal Plain pond which remained close to pH 6.4. Water temperature ranged from 30° C in June to 23° C near the end of August.Phytoplankton numbers were determined by the standard Sedgwick-Rafter method. Populations were low except for brief pulses. One Coastal Plain pond was typical of a fertilized pond and had several tremendous blooms of blue-green algae. The others supported a seemingly typical Caledonian flora, rich in species but low in number of individual organisms.There was no clear correlation between phytoplankton populations and any habitat factor except pH. This correlation is probably not direct but only an indication of water quality.This work was aided by Contract No. AT-(40-1) 2100 with the Division of Biology and Medicine, U. S. Atomic Energy Commission.     

Prostaglandin E2 production is enhanced in mice genetically selected to produce high affinity antibody responses

Spleen cells from mice selectively bred to produce high affinity antibody responses to protein antigens (HI) had reduced responses to both T and B cell mitogens when compared to those from mice selectively bred to produce low affinity (LO) responses. The reduced response by spleen cells from HI mice was partially reversed by the addition of indomethacin in vitro. Spleen adherent cells from HI mice had increased production of prostaglandin E2 when compared to those from LO mice. In addition, spleen adherent cells from mice which fail to show affinity maturation not only produced lower amounts of PGE2 than those from HI mice but also a decreased proportion of spleen cells adhered to plastic in these mice. To test the possibility that the increased PGE2 production in HI mice was responsible for the production of high affinity antibodies, indomethacin was administered in vivo and resulted in a significant reduction in antibody affinity. The possibility that PGE2 production may control the balance between the TH1 and TH2 cells of Mosmann and Coffman is discussed.     

Autologous perfusion of an isolated rabbit gastrointestinal tract.

Most perfusion techniques rely on mechanical means to provide blood flow to the isolated organ for maintaining its physiological conditions. The approach usually requires a complicated mechanical system with the associated problems of blood type matching and prevention of blood cell damage. This paper describes a gastrointestinal tract perfusion technique that uses the rabbit's own cardiopulmonary system as the autologous blood supply source. The technique allows for the removal of the complete intestinal loop from the abdominal cavity of the rabbit, and maintains its blood circulation through silastic tubing connections of the catheterized portal vein and cranial and caudal mesenteric arteries. An alternative perfusion site that uses the aorta as the arterial blood supply and the vena cava as the venous return also is described. The isolated perfused GI tract may then be placed in a separate test environment for controlled experiments. For an acute animal test, the approach was found to be a convenient alternative to conventional approaches.