To achieve surgical anesthesia in animal experimentation, it is important to select the appropriate anesthetic dose. However, few studies have investigated the reasonable anesthetic dose in tree shrew (Tupaia belangeri). The aim of the study was to review the literature to determine the most commonly used anesthetic dose in tree shrew and to calculate the reasonable equivalent dose between tree shrew and rat based on the body surface area conversion. Two groups of 10 adult tree shrews each were anesthetized with 1% sodium pentobarbital through intraperitoneal injection separately at doses of 62 mg/kg (equivalent dose) and 40 mg/kg (reported dose). Anesthetic depth and times were assessed in addition to vital signs. The results showed that the dosage was quite different across studies, ranging from 15 mg/kg to 80 mg/kg, with 40 mg/kg being the most frequently reported dose. However, the group of tree shrews anesthetized with the commonly reported dose were unable to meet the requirements of surgery. In contrast, the equivalent dose (62 mg/kg, intraperitoneal injection with sodium pentobarbital) calculated by body surface area conversion could achieve an anesthetic time of 44.28 ± 3.95 min with no serious or fatal effects. During anesthetic monitoring, we found that sodium pentobarbital had an inhibitory effect on the blood pressure, pulse rate, respiratory rate and rectal temperature in tree shrews, especially on the respiratory rate. Thus, our study indicated that the use of the equivalent dose of sodium pentobarbital was effective in anesthetizing tree shrews.

The release of manufactured nanomaterials (MNMs) into the environment has raised concerns about combined toxicological risks, as MNMs could significantly alter the environmental behavior and fate of co-existing contaminants. Numerous studies have been published on the combined toxicity of MNMs and co-existing contaminants, but the potential mechanisms controlling the combined toxicity, especially the biological response mechanism, remain unclear. This study investigated the combined toxicity of nano-titanium dioxide (nTiO2), a typical MNM, and the heavy metal cadmium (Cd2+), using Scenedesmus obliquus as the test organism. The molecular mechanism was examined under different concentrations, using an equivalent dose (toxic ratio 1 ∶1) on S. obliquus. The results showed that the 72h-EC50 of nTiO2 and Cd2+ at the equivalent dose was significantly higher than that of single exposure, indicating an antagonistic effect. Further transcriptomics analysis revealed that the photosynthesis, chlorophyll metabolism, and starch and sucrose metabolism pathways involved in the energy metabolism of S. obliquus were significantly up-regulated in the presence of nTiO2. The arginine and proline metabolic pathways related to the anti-stress effect of algae cells also showed positive stimulation. The results of this study provide an important reference and a research basis for in-depth understanding of the environmental effects of MNMs and co-existing contaminants.

Tree shrew (Tupaia belangeri) is a promising experimental animal in biomedical research, but the equivalent doses of drugs between tree shrew and human and other animals has not been explored, which hinders its further application in a wider scope. The main objective of this article is to provide a method of equivalent dose conversion between tree shrews and other species based on body surface area (BSA). BSA of tree shrews were measured by Image J software, and then the average Km value of tree shrews was figured out based on the body weights and BSA, then the conversion coefficients of equivalent dose among tree shrew and other species of experimental animals were calculated based known data. The Km value of tree shrews was 0.105 ± 0.001. Through BSA conversion, the equivalent dose for tree shrews (D-ts) relative to rats was obtained by formula: D-ts = 1.36 × D-a (rats weighing 200g as example), and the error was less than 10% when the BW of the tree shrew was 0.09 kg-0.15 kg. The coefficients of equivalent dose transferring from tree shrews to human and other species were calculated in article. These parameters could be used to determine a suitable dosing strategy for tree shrew studies.