The challenge of outcomes assessment.

While many programs undertake formal assessment of student learning outcomes to satisfy accreditation standards, the ultimate goal of outcomes assessment is program improvement and increased student achievement. Properly designed and executed, outcomes assessment should tell the program how well it is operating and the extent to which it is contributing to the growth and development of its students. It enables programs to determine if they are effective in producing graduates with the necessary knowledge, skills and values to function as valuable members of the health care team, thus contributing to improved quality of patient care.

Surface geochemistry of the clay minerals.

Clay minerals are layer type aluminosilicates that figure in terrestrial biogeochemical cycles, in the buffering capacity of the oceans, and in the containment of toxic waste materials. They are also used as lubricants in petroleum extraction and as industrial catalysts for the synthesis of many organic compounds. These applications derive fundamentally from the colloidal size and permanent structural charge of clay mineral particles, which endow them with significant surface reactivity. Unraveling the surface geochemistry of hydrated clay minerals is an abiding, if difficult, topic in earth sciences research. Recent experimental and computational studies that take advantage of new methodologies and basic insights derived from the study of concentrated ionic solutions have begun to clarify the structure of electrical double layers formed on hydrated clay mineral surfaces, particularly those in the interlayer region of swelling 2:1 layer type clay minerals. One emerging trend is that the coordination of interlayer cations with water molecules and clay mineral surface oxygens is governed largely by cation size and charge, similarly to a concentrated ionic solution, but the location of structural charge within a clay layer and the existence of hydrophobic patches on its surface provide important modulations. The larger the interlayer cation, the greater the influence of clay mineral structure and hydrophobicity on the configurations of adsorbed water molecules. This picture extends readily to hydrophobic molecules adsorbed within an interlayer region, with important implications for clay-hydrocarbon interactions and the design of catalysts for organic synthesis.

Neuropharmacological characterization of serotoninergic stimulation of vasopressin secretion in conscious rats.

In this study we have evaluated a possible role for brain serotoninergic neurons in the regulation of vasopressin secretion using pharmacological methods. In order to accomplish this, we have developed a specific and sensitive vasopressin radioimmunoassay along with a highly reproducible plasma extraction protocol. These tools were used to evaluate the plasma vasopressin response to several pharmacological challenges in conscious rats. Treatment with the serotonin (5-HT) releaser p-chloroamphetamine caused a significant increase in plasma vasopressin concentration. This effect was blocked by posterior hypothalamic deafferentation which separates serotonin cell bodies in the midbrain from their nerve terminals in the hypothalamus. Administration of graded doses of several 5-HT agonists had no effect. However, treatment with MK212, a serotonin agonist with 5-HT1 + 5-HT2 activity, induced a significant increase in plasma vasopressin concentration. The effect of MK212 on plasma vasopressin was completely abolished by the selective 5-HT2 receptor blocker LY53857. These studies confirm and extend studies by others that provide pharmacological evidence for serotoninergic regulation of vasopressin secretion via a selective 5-HT2 receptor mechanism. The specific neuroanatomical site(s) where serotonin exerts this effect are unknown, and the physiological consequences of these studies remain to be established.

In vivo reconstitution of ricin-like activity from its A and B chain subunits.

The capacity of highly purified preparations of ricin A and B chains to reconstitute ricin toxicity both in vitro and in vivo was studied. When the nontoxic A and B chain subunits were mixed and electrophoresed on sodium dodecyl sulphate-polyacrylamide gels (SDS-PAGE), reconstituted ricin was observed. The mixtures killed cells of the human Burkitt's lymphoma cell line Daudi in vitro and killed mice after i.v. injection. It was also shown that when mice were injected with one ricin subunit followed by administration of the complementary polypeptide up to 8 hr later, they died with lesions similar to those of ricin-induced death. This observation suggests that A and B chains recombine either in the serum or on the surface of cells. The rate of clearance of A and B chains from the blood of rats indicated that sufficient concentrations of either chain were present in the circulation 8 hr after injection to account for the observed toxicity. The above studies therefore suggest that the subunits of ricin have a very high affinity for each other and are capable of reconstituting biologically active ricin in vitro and in injected mice.

CT of acquired cystic kidney disease and renal tumors in long-term dialysis patients.

The kidneys of long-term dialysis patients frequently demonstrate multiple small acquired cysts and renal cell tumors on pathologic examination. The original kidneys of 30 long-term dialysis patients and six renal transplant patients were evaluated by computed tomography to determine the incidence of these abnormalities. Among dialysis patients, 43.3% had diffuse bilateral cysts, while 16.7% had occasional cysts (fewer than five per kidney), and 40% showed no renal cysts. Seven solid renal tumors were detected in four dialysis patients with renal cysts. Acquired cystic kidney disease tends to result in renal enlargement, is more common in patients who have been maintained on dialysis for prolonged periods, and may lead to spontaneous renal hemorrhage. The six transplant patients showed no evidence of renal cysts, and all had markedly shrunken kidneys. Acquired cystic disease and renal cell tumors in the original kidneys of dialysis patients may be due to biologically active substances that are not cleared effectively by dialysis but that are removed by normally functioning transplant kidneys.