Comparative sensitivities of larval stages of the cane toad, Rhinella marina, and the striped marsh frog, Limnodynastes peronii, to atrazine

Variations in larval sensitivities to atrazine were determined in the Australian native striped marsh frog, Limnodynastes peronii, and the introduced cane toad, Rhinella marina. The static acute test design involved six nominal concentrations of atrazine, including control, solvent control, 3, 6, 12, and 24 mg L⁻¹. Gosner stages 22–23 as hatchlings, stages 25–26, 28–29, and 32–33 as premetamorphic, 36–37 as prometamorphic and 40–41 as metamorphic climax stages of cane toads and the first four sets of Gosner stages of striped marsh frogs were exposed to atrazine treatments for 96 h. Results showed that late larval stages were more sensitive than early stages and different premetamorphic stages showed variations in sensitivities in both test species. The striped marsh frog showed a stronger concentration- and stage-dependent response and greater sensitivity to atrazine than the cane toad. In both experimental species, Gosner stages 28–29 showed better concentration-dependent increase in sensitivities to atrazine compared with other larval stages. It can be concluded that inter- and intra-species variations in sensitivities to atrazine may occur in Australian anurans and native species may show greater sensitivity to acute concentrations of atrazine than the introduced cane toad.8 page(s

Importance of the study of atrazine toxicity to amphibians in the Australian environment

Global amphibian declines have been of great concern over recent years due to a number of increasing natural and anthropogenic stressors. Reproductive and developmental abnormalities in amphibians have been reportedly linked to pesticide exposures and atrazine is one such pesticide that is of particular concern. Studies have shown gonadal deformities in frogs exposed to atrazine concentrations as low as 0.1 µg/L. The majority of amphibian toxicity tests have been run using the African clawed frog, Xenopus laevis; however, the use of Australian native frogs in toxicity testing is limited. Differences in sensitivity to environmental contaminants may exist between Australian amphibians compared to overseas frog species. Atrazine is one ofthe most widely applied herbicides and is commonly detected in surface and groundwater samples. Australian native frog susually breed during late spring and summer, which is the peak time for applying atrazine to agricultural fields. Therefore, their breeding sites adjacent to the agricultural fields can potentially become contaminated with atrazine. The Australian Pesticides and Veterinary Medicines Authority has reviewed atrazine several times due to its concern for human and animal health after frequent detection in surface and ground waters; however, most of the reviews were based on mammalian and/or overseas studies. Therefore, the aim of this review was to: 1) detail the present scenario of atrazine in Australia, particularly in Queensland where agriculture is an important industry, and 2) assess likely atrazine toxicity to amphibians in order to highlight the potential harm in the Australian environment

Preparation and characterization of naproxen solid dispersion using different hydrophilic carriers and in-vivo evaluation of its analgesic activity in mice

Background: Solid dispersion (SD) has been used conventionally as a successful technique for improving the dissolution profile and bioavailability of poorly water-soluble drugs. The aim of this study was to progress the dissolution rate and bioavailability of naproxen (BCS class II) by SD technique. Materials &amp; methods: In this study, hydrophilic carriers are used for preparing solid dispersion of naproxen by evaporation method. The prepared optimized SDNs were evaluated by in-vitro drug dissolution test, differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), powder X-ray diffraction (PXRD), and scanning electron microscopy (SEM). The in-vivo analgesic effects tests of the optimized SDNs (SDN-2 and SDN-5) were performed by tail immersion method and writhing method. Results: All the prepared SDNs exhibited a significant increase in the dissolution of naproxen compared to that of the pure drug. Among them, SDN-2 (the dispersion with sodium starch glycolate at 1:2 ratio of naproxen and sodium starch glycolate) and SDN-5 (using the combination of PEG-8000 and sodium starch glycolate with naproxen at 1:1:1 ratio) showed faster dissolution rate as compared to other solid dispersions (SDNs) and pure naproxen. SDN-2 showed 5.4 times better dissolution rate and SDN-5 depicted 6.5-fold increment of dissolution rate compared to pure naproxen drug. DSC, PXRD and SEM microscopy showed that the drugs crystallinity was decreased during the preparation process. FTIR study revealed that naproxen was stable in polymeric dispersions and there was no interaction among the drug and polymers. In writhing method, the percentage inhibition of the number of writhes showed significantly greater (p < 0.01), (p < 0.0001) analgesic activity for the higher dose treatment groups SDN-2(H), and SDN-5(H), respectively, when contrasted to the pure drug naproxen. For tail immersion test, there is increase in latency time at 90 min which is significantly greater (P < 0.01), (P < 0.05), (P < 0.01) for treatment groups SDN-2(H), SDN-5(L), and SDN-5(H), respectively that ultimately authenticates that the optimized SDNs (SDN-2, SDN-5) showed better analgesic activity in mice in comparison with the pure drug. Conclusion: It can be concluded that dissolution of the naproxen could be improved by the making solid dispersion using sodium starch glycolate and/or combination of sodium starch glycolate and PEG 8000 due to the complete transformation of drug into amorphous form with the entire loss of crystallinity, as evidenced by DSC, PXRD, and SEM and also consequences the enhanced analgesic activity in mice

Topographical and biometrical anatomy of the digestive tract of White New Zealand Rabbit (Oryctolagus cuniculus)

Objective: This study was constructed to build up the normal dimensions of the digestive tract of domestic Rabbit (Oryctolagus cuniculus). Materials and methods: Five rabbits of both sexes were used in this study. After dissection of the rabbits, the exact positions of different parts of the digestive tract (i.e., esophagus, stomach, small intestine, large intestine) were measured using Metric rule, thread, electronic and normal balance. Results: The mean lengths of the small intestine and large intestine were 169.53+/-21.65 and 132.3+/-17.42 cm, respectively, and weight of the whole digestive tract was 263.60+/-56.80 gm. The mean lengths and mean diameter of esophagus, duodenum, jejunum, ileum, cecum, colon and rectum were 9.62+/-1.64, 41.26+/-4.06, 106.60+/-14.64, 21.64+/-46.32, 41.14+/-2.82, 83.16+/-13.74 and 8.0+/-1.08 cm and 1.16+/-0.12, 1.71+/-0.11, 1.70+/-0.09, 1.73+/-0.05, 5.47+/-0.15, 3.36+/-0.16 and 2.81+/-0.24 cm, respectively. Conclusion: These results can be considered as a baseline study that may assist in disease diagnosis and clinical works with rabbits. [J Adv Vet Anim Res 2016; 3(2.000): 145-151

Comparative sensitivities of larval stages of the cane toad, Rhinella marina, and the striped marsh frog, Limnodynastes peronii, to atrazine

Variations in larval sensitivities to atrazine were determined in the Australian native striped marsh frog, Limnodynastes peronii, and the introduced cane toad, Rhinella marina. The static acute test design involved six nominal concentrations of atrazine, including control, solvent control, 3, 6, 12, and 24 mg L–1. Gosner stages 22–23 as hatchlings, stages 25–26, 28–29, and 32–33 as premetamorphic, 36–37 as prometamorphic and 40–41 as metamorphic climax stages of cane toads and the first four sets of Gosner stages of striped marsh frogs were exposed to atrazine treatments for 96 h. Results showed that late larval stages were more sensitive than early stages and different premetamorphic stages showed variations in sensitivities in both test species. The striped marsh frog showed a stronger concentration- and stage-dependent response and greater sensitivity to atrazine than the cane toad. In both experimental species, Gosner stages 28–29 showed better concentration-dependent increase in sensitivities to atrazine compared with other larval stages. It can be concluded that inter- and intra-species variations in sensitivities to atrazine may occur in Australian anurans and native species may show greater sensitivity to acute concentrations of atrazine than the introduced cane toad