Retinal remodeling in human retinitis pigmentosa.

Retinitis Pigmentosa (RP) in the human is a progressive, currently irreversible neural degenerative disease usually caused by gene defects that disrupt the function or architecture of the photoreceptors. While RP can initially be a disease of photoreceptors, there is increasing evidence that the inner retina becomes progressively disorganized as the outer retina degenerates. These alterations have been extensively described in animal models, but remodeling in humans has not been as well characterized. This study, using computational molecular phenotyping (CMP) seeks to advance our understanding of the retinal remodeling process in humans. We describe cone mediated preservation of overall topology, retinal reprogramming in the earliest stages of the disease in retinal bipolar cells, and alterations in both small molecule and protein signatures of neurons and glia. Furthermore, while Müller glia appear to be some of the last cells left in the degenerate retina, they are also one of the first cell classes in the neural retina to respond to stress which may reveal mechanisms related to remodeling and cell death in other retinal cell classes. Also fundamentally important is the finding that retinal network topologies are altered. Our results suggest interventions that presume substantial preservation of the neural retina will likely fail in late stages of the disease. Even early intervention offers no guarantee that the interventions will be immune to progressive remodeling. Fundamental work in the biology and mechanisms of disease progression are needed to support vision rescue strategies.

Preliminary Tests of a Laboratory Chamber Technique Intended to Simulate Pesticide Volatility in the Field.

Pesticides volatilize into the atmosphere in measurable quantities and concentrations; however, reliable methods of trapping pesticide vapors are not readily available. Laboratory simulations of field pesticide volatilization can provide information from which inferences can be made regarding actual field-scale volatilization. The objective of this study was to evaluate a simple laboratory technique that can be used to simulate field volatilization of pesticide vapor, in this particular case metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide] vapor. In addition, this study was also used to evaluate the trapping efficiency of XAD-8 sorbent resin for metolachlor. A custom-designed volatilization chamber consisting of a 1.5-L bell-shaped jar was fitted with a vacuum air check valve. The chamber was connected to an air sampling tube that was filled with a polymeric resin, XAD-8, to trap metolachlor vapor. The air sampling tube was connected to a computerized air sampling pump, which could be programmed to sample air from the chamber at a variety of different flow rates and sampling intervals. The volatilization chamber was used inside of a controlled environment chamber to measure metolachlor volatilization from a glass surface over a 24-h period. Total metolachlor recovery averaged 102%. Total metolachlor volatilized under the controlled conditions of this study averaged 84%. Metolachlor trapped by the XAD-8 sorbent averaged 65%. The chamber design performed satisfactorily and when used inside a controlled-environment chamber provides a means of evaluating the effects of various microclimate parameters that influence pesticide volatilization.

Evaluation of a commercial immunoassay system for sulfamethazine and aflatoxin detection in biological fluids and feeds.

Commercial immunoassay systems produced by International Diagnostics to analyze for sulfa drugs and aflatoxin residues have been evaluated with milk, urine, feed and serum samples. Neither system produced satisfactory results with feeds. The sulfa test reproducibility was good enough to provide semiquantitative results on milk (40 ul sample) and urine, but should be regarded as qualitative on urine or feed. The reproducibility of the aflatoxin test was acceptable for semiquantitative use on serum, but should be regarded as qualitative on urine and semiquantitative on milk with a solid phase concentration. The overall reproducibility was at least +/- 10% if the test was used semiquantitatively. The sensitivity of the test was 10 ng for both sulfamethazine and aflatoxin B1. The range of the color change was very narrow (0-20 ng). The aflatoxin test was designed for aflatoxin B1 and was roughly twice as sensitive to B1 as to M1 aflatoxin. These procedures can be used on appropriate matrices at suitable sensitivities to rapidly screen samples for sulfa drugs and aflatoxin residues. The use of proper standards to demonstrate effectiveness in each matrix is very important.