Evaluation of large volume yeast interfering RNA lure-and-kill ovitraps for attraction and control of Aedes mosquitoes.

Aedes mosquitoes (Diptera: Culicidae), principle vectors of several arboviruses, typically lay eggs in man-made water-filled containers located near human dwellings. Given the widespread emergence of insecticide resistance, stable and biofriendly alternatives for mosquito larviciding are needed. Laboratory studies have demonstrated that inactivated yeast interfering RNA tablets targeting key larval developmental genes can be used to facilitate effective larvicidal activity while also promoting selective gravid female oviposition behaviour. Here we examined the efficacy of transferring this technology toward development of lure-and-kill ovitraps targeting Aedes aegypti (L.) and Aedes albopictus (Skuse) female mosquitoes. Insectary, simulated field and semi-field experiments demonstrated that two mosquito-specific yeast interfering RNA pesticides induce high levels of mortality among larvae of both species in treated large volume containers. Small-scale field trials conducted in Trinidad, West Indies demonstrated that large volume ovitrap containers baited with inactivated yeast tablets lure significantly more gravid females than traps containing only water and were highly attractive to both A. aegypti and A. albopictus females. These studies indicate that development of biorational yeast interfering RNA-baited ovitraps may represent a new tool for control of Aedes mosquitoes, including deployment in existing lure-and-kill ovitrap technologies or traditional container larviciding programs.

Endoscopic assessment of the duodenum in dogs with inflammatory bowel disease.

BACKGROUND: Endoscopy is performed for direct inspection of the mucosa and acquisition of biopsies in dogs with inflammatory bowel disease (IBD). AIM: To evaluate the interobserver agreement in the endoscopic assessment of duodenal mucosa in dogs with IBD. METHODS: Thirty-five archived endoscopic images of grossly normal (n = 6) and inflamed (n = 29) duodenal mucosa were displayed to 3 expert and 5 trainee endoscopists. Each image was assessed independently by endoscopists for mucosal abnormalities using established indices (of hyperemia, granularity, friability, lymphatic dilatation, and erosions) or interpreted as normal mucosa (trial 1). A repeated trial (trial 2) was performed with the same images presented in random order 1 month later, and accompanied by a visual template. RESULTS: There was slight interobserver agreement in initial mucosal assessment for expert and trainee endoscopists in trial 1 (kappa ≤ 0.02, P > .05). Interobserver agreement improved in trial 2 for both expert and trainee endoscopists (kappa = 0.2, P > .05) for experts and (P < .05) for trainees. There was a significant (P < .01) improvement in trainee endoscopy scores of lesions from trial 1 to trial 2. Regression analysis showed a significant (P < .01) difference between expert versus trainee endoscopy scores in trial 1. Repeat lesion assessment aided by use of a visual template (trial 2) improved the overall scores of trainee endoscopists to near that of expert endoscopists (P = .06). CONCLUSIONS AND CLINICAL IMPORTANCE: Interobserver agreement of IBD mucosal appearance from endoscopic findings benefitted from operator experience.

Subcellular accumulation of beta-carotene and retinoids in growth-inhibited NCI-H69 small cell lung cancer cells.

Delivery of beta-carotene in tetrahydrofuran slowed the growth of NCI-H69 small cell lung cancer cells. Analysis of cells and cellular fractions revealed that beta-carotene-treated cells accumulated beta-carotene as well as some polar metabolites, primarily in the crude nuclei. Cells were grown at 1 x 10(5) cells/ml and treated with 20 microM beta-carotene. Growth monitoring up to 15 days indicated an inverse relationship between the duration of beta-carotene treatment and the rate of cell growth. Reverse-phase high-performance liquid chromatography analysis of treated cells showed the presence of beta-carotene, retinoic acid, retinol, and retinal, with beta-carotene accounting for the major material recovered. When cellular fractions were analyzed for beta-carotene, it was found to be located primarily in the crude nuclei. These results demonstrate that treatment of small cell lung cancer cells with beta-carotene results in a reduced growth of the cells. Further investigation is required to show a direct effect of beta-carotene or its intracellular polar metabolites on these cells. Accumulation of beta-carotene in the nucleus suggests a need for evaluating the nuclear role for beta-carotene.

Determination of lycopene, alpha- and beta-carotene and retinyl esters in human serum by reversed-phase high performance liquid chromatography.

A rapid specific, microdetermination of the major human blood carotenoids by high performance liquid chromatography (HPLC) separation and quantitation at 466 nm is detailed in this paper. Serum retinyl esters can also be quantified utilizing the same separation procedure but detected at 325 nm. One hundred microliters of deproteinated serum were extracted with chloroform and injected on a reverse-phase column. Separation occurred within 16 min for all compounds of interest employing a mobile solvent of MeOH/AcN/CHCl3 (47:47:6). All compounds were quantified at the wavelengths cited by integrated peak areas using retinyl acetate as a daily standard. Analysis of serum from a hypercarotenemic anorexia nervosa patient and a person suffering from hypervitaminosis A are presented as examples of the clinical application of this procedure.

Effect of dietary retinyl acetate, beta-carotene and retinoic acid on wound healing in rats.

The effects of feeding various levels and combinations of retinyl acetate, beta-carotene, or retinoic acid on skin wound healing in rats was investigated. Weanling male Sprague-Dawley rats were fed a vitamin A-free diet for 2 weeks to produce marginal vitamin A status. After a paravertebral incision was made and closed with suture, one of several diets were fed for either 5 or 14 days. Surgery and recovery did not reduce liver vitamin A nor serum retinol levels compared to nonoperated pair-fed controls. Supplemental retinyl acetate feeding at five times the NRC-suggested allowance resulted in a mild, but significantly increased postmortem wound tensile strength after 5 days compared to rats fed the suggested allowance. Although a low level of retinoic acid in the diet (1.3 microgram/g diet) depressed wound strength at 5 days, a higher level (5.2 microgram/g) increased the strength 57% above controls. Still higher levels (49.1 microgram/g) did not further increase the tensile strength of the wound. beta-Carotene fed the requirement level for 5 days (with compensation made for utilization as one-sixth that of retinol) doubled wound strength compared to rats fed the requirements as retinyl acetate. Vitamin A feeding did not enhance wound strength after 14 days of feeding. It is concluded that supplemental retinyl acetate, beta-carotene, or in some cases all-trans-retinoic acid can be effective in enhancing wound strength, 5 days, but not 14 days after surgery, of young male rats with marginal vitamin A status.

Changes in lipid metabolism during retinoid administration.

Administration of oral vitamin A and the synthetic retinoids to humans and experimental animals has been accompanied by changes in lipid metabolism. these changes include alterations in serum, liver, and skin surface lipids. While the immediate cause(s) of the serum and liver changes remain(s) obscure, the skin surface lipid alterations appear to be secondary to changes in sebum production. The most marked effect of retinoid feeding seen in clinical or animal studies is that of hypertriglyceridemia. The increased serum triglycerides are found primarily in the very low-density lipoprotein (VLDL) fraction of the blood and occur during both the fasted and fed state. In rats, oral all-trans-retinoic acid, 13-cis-retinoic acid, and natural vitamin A have resulted in hypertriglyceridemia, while in man, 13-cis-retinoic acid, etretinate, and natural vitamin A have been reported to elicit this response. Current studies using the rat indicate that elevated serum triglycerides may be secondary to both increased liver secretion and decreased extrahepatic breakdown. Ongoing work from our laboratory and the possible primary causes of the systemic lipid changes are discussed.

Hyperlipidemia in rats fed retinoic acid.

This report describes a series of experiments that attempt to characterize the lipidemia accompanying retinoic acid administration. After feeding young adult male Sprague-Dawley rats, 1.2 Retinol Equivalents (R.E.) retinyl acetate plus supplemental retinoic acid (100 microgram/g dry diet) for three days and fasting for 6-8 hr, triglyceride, cholesterol, and phospholipid content of various serum lipoprotein fractions were determined. When compared to unsupplemented controls, both the serum very low density lipoprotein (VLDL) and the high density lipoprotein (HDL) fractions of the retinoic acid-fed rats were found to harbor an elevated triglyceride content. While VLDL cholesterol and phospholipid content were also elevated, total serum cholesterol and phospholipids were not statistically altered. The detergent Triton WR-1339 was used to depress serum triglyceride clearance in order to assess the effects of retinoic acid feeding on serum triglyceride levels. Triglyceride accumulation started earlier after Triton treatment and was greater when rats were fed 100 microgram/g retinoic acid for three days prior to testing. Red and white gastrocnemius muscle, cardiac ventricular muscle, and perirenal adipose tissue were removed from rats following retinoic acid feeding. Analysis of these tissues for lipoprotein lipase (EC 3.1.1.3) activity showed a decrease in adipose tissue, a large depression in both areas of gastrocnemius muscle and no change in cardiac muscle as a result of retinoic acid feeding.

Comparative effects of all-trans and 13-cis retinoic acid administration on serum and liver lipids in rats.

The effects of all-trans and 13-cis retinoic acid upon serum and liver lipids were investigated in Sprague-Dawley rats. Groups of rats were fed daily with 105, 210 and 315 micrograms/g diet of one of the retinoids for periods of up to 8 days. Other groups were injected intraperitoneally (I.P.) daily with retinoids at levels equivalent to the daily intake of rats receiving 105 or 210 micrograms of retinoid/g diet. All dietary concentrations of all-trans retinoic acid induced hypertriglyceridemia, however, only the highest dietary concentration of the 13-cis form caused this response. Injection of the all-trans form consistently increased serum triglycerides, while 13-cis retinoic acid did so in only one case. Retinoid-fed rats fasted for 6 hours before blood sampling demonstrated similar increases in serum triglycerides compared to their respective controls. Also, retinoid administration reduced serum retinol at all levels tested with the all-trans form appearing to be more potent. Growth and feed intake was somewhat reduced in rats receiving the highest level of all-trans retinoic acid. Liver analysis did not reveal fatty liver or alterations in phospholipid, cholesterol, or vitamin A content in any groups monitored. Our previous studies have shown induction of hypertriglyceridemia when rats were fed as low as 26 micrograms/g diet of all-trans retinoic acid. The current studies would indicate that feeding 315 micrograms/g diet of the 13-cis isomer was required to elicit a similar response.

Effect of retinoic acid and retinyl acetate feeding upon lipid metabolism in adrenalectomized rats.

Many reports have appeared in the literature suggesting that vitamin A may exert some of its effects via changes in adrenocortical activity. A series of experiments were performed in order to assess the possible role of the adrenal gland in vitamin A-induced lipid alterations in rats. Adrenalectomized, sham-operated, and intact rats were fed retinoic acid or retinyl acetate at several levels. Either 25 or 100 retinol equivalents (RE)/g dry diet were fed to male Sprague-Dawley rats for periods of 7 or 28 days. Neither compound had an effect on the concentration of liver glycerides, phospholipids, cholesterol, or total lipids. Vitamin A, especially in the form of retinoic acid, was found to induce an elevation of plasma triglycerides. The presence of the adrenal gland was not necessary for the induction of hypertriglyceridemia nor was there any indication of increased adrenocortical output (as measured by plasma corticosterone level) as a result of vitamin A feeding. There was a reduction in circulating retinol as a result of retinoic acid feeding at either 25 or 100 RE in sham-operated and adrenalectomized rats but not in unoperated rats. These experiments demonstrate that vitamin A, especially in the form of retinoic acid, fed at as low as 25 RE/g diet to the rat can induce hypertriglyceridemia, and that the adrenal gland does not mediate this effect.