Culture of ratretinal pigment epithelium

Summary A method of preparing monolayer cultures of retinal pigment epithelium from normal pigmented neonatal rats is described. Critical features include incubating the eyes in balanced salt solution and treating with trypsin before dissecting the eyes. The tissue also has been cultured from RCS rats with inherited retinal degeneration. Since the pigment epithelium has been shown to be the primary site of action of the gene for retinal dystrophy in the RCS rat, the method should be useful in studying the defect(s) associated with this mutation. This work was supported by grants from the National Retinitis Pigmentosa Foundation, Baltimore, Maryland, and the George Gund Foundation, Cleveland, Ohio. Breeding pairs of RCS-p⁺ rats were provided through National Institutes of Health Research Contract EY-3-2133 to Dr. R. L. Sidman.     

Time-varying-response smoothing

Cubic smoothing splines with a fixed-period response are used widely in producing “expected” growth curves for ring-width and density data in dendroclimatology. A simple modification to the procedure which generates these splines enables the use of a smoothing spline with a user-specified, time-varying flexibility and hence time-varying-response characteristics. The revised procedure is presented here, along with different examples of its application in the context of Regional Curve Standardisation (RCS). The ability to generate a smoothing spline with time-dependent flexibility may have wider application in tree-ring studies.     

Anti-thromboxane activity in Rhodnius prolixus salivary secretion

The salivary secretion of Rhodnius prolixus inhibits arachidonic acid-induced platelet aggregation and the accompanying rabbit aorta-contracting activity. Results are presented that show antagonism to thromboxane A₂ on both platelet aggregation and rabbit aorta preparations. The antagonist is heat stable, non degradable by pronase, non dialysable and is sensitive to periodate oxidation.A brief review of the pharmacological properties of Rhodnius saliva is presented. It is suggested that Rhodnius prolixus developed salivary anti-haemostatic components that allows them to take a large meal in a short time.