A Murine Model of Irreversible and Reversible Unilateral Ureteric Obstruction

Obstruction of the kidney may affect native or transplanted kidneys and results in kidney injury and scarring. Presented here is a model of obstructive nephropathy induced by unilateral ureteric obstruction (UUO), which can either be irreversible (UUO) or reversible (R-UUO). In the irreversible UUO model, the ureter may be obstructed for variable periods of time in order to induce increasingly severe renal inflammation and interstitial fibrotic scarring. In the reversible R-UUO model the ureter is obstructed to induce hydronephrosis, tubular dilation and inflammation. After a suitable period of time the ureteric obstruction is then surgically reversed by anastomosis of the severed previously obstructed ureter to the bladder in order to allow complete decompression of the kidney and restoration of urinary flow to the bladder. The irreversible UUO model has been used to investigate various aspects of renal inflammation and scarring including the pathogenesis of disease and the testing of potential anti-inflammatory or anti-fibrotic therapies. The more challenging model of R-UUO has been used by some investigators and does offer significant research potential as it allows the study of inflammatory and immune processes and tissue remodeling in an injured and scarred kidney following the removal of the injurious stimulus. As a result, the R-UUO model offers investigators the opportunity to explore the resolution of kidney inflammation together with key aspects of tissue repair. These experimental models are of relevance to human disease as patients often present with obstruction of the renal tract that requires decompression and are commonly left with significant residual kidney impairment that has no current treatment options and may lead to eventual end stage kidney failure.     

Comparison of chemosensory behavior and prey trail-following in the varanoid lizards Varanus gouldii and Heloderma suspectum

In the first of three experiments, Gould's monitor lizards Varanus gouldii (n = 8) and Gila monsters Heloderma suspectum (n = 8) were tested to determine whether a postingestion elevation in tongue-flick rate (PETF) occurred. Based on analysis of numbers of tongue-flicks during 20 successive minutes following treatments and controls, significant PETF was detected in V. gouldii. Analysis of numbers of tongue-flicks over 20 successive minutes for H. suspectum indicated that PETF did not occur. A second experiment with refined procedures confirmed the absence of PETF in our H. suspectum. The third experiment was designed to determine whether V. gouldii and H. suspectum were capable of following prey-chemical trails. Varanus gouldii and H. suspectum followed these trails, and did so equally well, whether or not prey were bitten and ingested prior to exposure to chemical trails. © 1996 Wiley-Liss, Inc.     

Phyletic aspects of the distribution of 3-hydroxyretinal in the class insecta

Summary The distribution of 3-hydroxyretinal (R₃), a recently discovered retinoid used as the visual pigment chromophore in some insects, was investigated in the class Insecta using HPLC technology. We studied 138 species in 24 orders, sampling from a wide range of taxonomic groups as well as varied habitats. In addition to groups already known to have R₃, we find this retinoid in Hemiptera (suborder Heteroptera), Plecoptera, Megaloptera, and Hymenoptera. We also find retinal (R₁) in Hemiptera (suborder Homoptera), Mecoptera, and Trichoptera, groups previously thought to have only R₃. The pattern of R₃ occurrence indicates that this retinoid cannot be considered a phylogenetic marker, having a scattered distribution in the class Insecta as well as within some orders of insects. Several environmental factors that might influence the selection of chromophore have been considered, but none correlates with its distribution. The evolutionary reasons for the pattern of occurrence of R₃ therefore remain unknown.     

A chromatographic technique for the analysis of oxidized metabolites: Application to carcinogenic N-hydroxyarylamines in urine

A new chromatographic detection method for oxidized metabolites has been developed based on the reaction of eluted compounds with an Fe⁺³-bathophenanthroline colorimetric reagent in a postcolumn reactor. The method is sensitive to N-hydroxyarylamines, aryldiamines, phenolic amines, and ascorbic acid. It has been applied to the analysis of toxic N-oxidized metabolites in rhesus monkey urine after the animals were dosed with the bladder carcinogens, 1- and 2-napthylamine. These compounds are oxidized to the corresponding N-hydroxyarylamines in the liver, conjugated as the N-glucuronide, and excreted in the urine. The N-glucuronide has been shown to undergo acidic hydrolysis in the urine to release the free N-hydroxyarylamine, an ultimate carcinogen for the induction of bladder tumors. In this study, the N-hydroxy-N-glucuronide of 2-naphthylamine was found to be excreted at a rate that was 6.8 times that of the 1-naphthylamine isomer. This is consistent with the much higher carcinogenic potency of 2-naphthylamine in a variety of species.