The effect of diphenylhydantoin on LD 50 of ouabain was investigated in frogs, using "one hour frog method". LD50 of ouabain in control group was 1.90 microg/10g. A dose of 100 microg/10g diphenylhydantion did not affect the systemic manifestations of the frogs, but increase the LD50 of ouabain to 2.60 microg/10g. The difference of LD50 of ouabain and potency ratio between control group and diphenylhydantoin-treated group was statistically significant.
Lethal Dose 50 ; Ouabain* ; Phenytoin*

This study was performed to investigate the antibacterial, antioxidant, and termite repellent effects of citronella oil (CiO) and lemongrass oil (LO). When the antibacterial activity against Staphylococcus (S.) aureus with various levels of antibacterial resistance were tested, a 0.05% concentration of CiO and LO completely inhibited the growth of all tested S. aureus strains. Evaluation of the antioxidant effect demonstrated that the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity of CiO was 2~3 times greater than that of LO. Among trial products made with various combinations of CiO and LO, a CiO : LO ratio of 6 : 4 had the most potent termite repellent effects. Assessment of acute toxicity of the trial product showed that the LD50 was more than 2,000 mg/kg. Based on the above results, CiO and LO have antibacterial, antioxidant, and termite repellent activities. Therefore, both compounds could be potential termites repellent reagents.
Antioxidants ; Cymbopogon* ; Indicators and Reagents ; Isoptera ; Lethal Dose 50 ; Staphylococcus

OBJECTIVE: To evaluate the molluscicidal activity of surfactin against Oncomelania hupensis, so as to provide the experimental basis for use of Bacillus for killing O. hupensis. METHODS: O. hupensis snails were collected from schistosomiasisendemic foci of Wuhu City on September 2022, and Schistosoma japonicum-infected snails were removed. Then, 60 snails were immersed in surfactin at concentrations of 2, 1, 0.5, 0.25, 0.125 mg/mL and 0.062 5 mg/mL for 24, 48, 72 hours at 26 °C, while ultrapure water-treated snails served as controls. The median lethal concentration (LC₅₀) of surfactin against O. hupensis snails was estimated. O. hupensis snails were immersed in surfactin at a concentration of 24 h LC₅₀ and ultrapure water, and then stained with propidium iodide (PI). The PI uptake in haemocyte was observed in O. hupensis snails using fluorescence microscopy. RESULTS: The mortality of O. hupensis was 5.0% following immersion in surfactin at a concentration of 0.062 5 mg/mL for 24 h, and the mortality was 100.0% following immersion in surfactin at a concentration of 2 mg/mL for 72 h, while no snail mortality was observed in the control group. There were significant differences in the mortality of O. hupensis in each surfactin treatment groups at 24 (χ² = 180.150, P < 0.05), 48 h (χ² = 176.786, P < 0.05) and 72 h (χ² = 216.487, P < 0.05), respectively. The average mortality rates of O. hupensis were 38.9% (140/360), 62.2% (224/360) and 83.3% (300/360) 24, 48 h and 72 h post-immersion in surfactin, respectively (χ² = 150.264, P < 0.05), and the 24, 48 h and 72 h LC₅₀ values of surfactin were 0.591, 0.191 mg/mL and 0.054 mg/mL against O. hupensis snails. Fluorescence microscopy showed more numbers of haemocytes with PI uptake in 0.5 mg/mL surfactintreated O. hupensis snails than in ultrapure water-treated snails for 24 h, and there was a significant difference in the proportion of PI uptake in haemocytes between surfactin-and ultrapure water-treated snails (χ² = 6.690, P < 0.05). CONCLUSIONS Surfactin is active against O. hupensis snails, which may be associated with the alteration in the integrity of haemocyte membrane.
Animals ; Molluscacides/pharmacology* ; Snails ; Schistosoma japonicum ; Lethal Dose 50 ; Water

PURPOSE: To evaluate the effects of Tranilast gamma on the cellular proliferation and expression of alpha-smooth muscle actin on the cultured keratocytes of the rabbit that influence the formation of corneal scar and haze in vitro. METHODS: After the keratocytes of the rabbit were cultured, they were exposed to Tranilast gamma (N-(3, 4-dimethoxycinnamoyl) anthranilic acid) 0.05, 0.1, 0.2, 0.4, 0.8, 1.0, 1.6 mg/ml with DMEM used as a control. MTT was used to measure the metabolic activity, and the Western blot assay was performed to confirm the alpha-smooth muscle actin expression, which was expressed with time by Tranilast gamma treatment. RESULTS: Higher the concentration and longer the exposure time of Tranilast gamma, the more the inhibition of the cellular proliferation. LD50 concentration was about 0.4 mg/ml in the exposure time of 24 hours and 0.2 mg/ml in the exposure time of over 48 hours(P<0.05). There was a decrease in response of alpha-smooth muscle actin expression with increasing concentrations of Tranilast gamma relative to the control. CONCLUSIONS: Tranilast gamma trends to have an inhibitory effect on the cellular proliferation and induction of alpha-smooth muscle actin expression. Tranilast gamma may inhibit excessive haze of the cornea and inhibit scar formation after the corneal wound healing and photorefractive surgery in the cornea.
Actins* ; Blotting, Western ; Cell Proliferation* ; Cicatrix ; Cornea ; Lethal Dose 50 ; Wound Healing

Live Vibrio vulnificus is highly cytotoxic to host cells in vivo and in vitro. The two most representative cytotoxins, cytolytic hemolysin and elastolytic protease, have been regarded to play major roles in the cytotoxicity of V. vulnificus. To further determine roles of the two cytotoxins in V. vulnificus pathogenesis, we constructed a double mutant of vvhA and vvpE genes, encoding a hemolysin and a protease, respectively. However, the cytotoxicity and the LD50 of a vvhA/vvpE double mutant showed no significant difference from those of the isogenic wild type strain. From these results, we came to speculate that yet unidentified, key cytotoxic factors should play a major role in the cytotoxic activity of V. vulnificus. The HeLa cells encountered with V. vulnificus became rounded, following detachment from the bottom of culture plate, and were killed eventually. However, the bacterial culture supernatant did not show any effect on the morphology and viability of HeLa cells. Also, no cytotoxicity could be noted when V. vulnificus was not allowed to contact with HeLa cells in the TranswellR system. Chloramphenicol, at lower concentration than minimum inhibitory concentration (MIC), decreased the cytotoxicity of a vvhA/vvpE double mutant to HeLa cells in a dose dependent manner. These results suggest that close encounter of V. vulnificus with host cells is a prerequisite to the cytotoxicity and that a yet unidentified virulence factor (s) should play an important role in the contact-dependent cytotoxicity.
Chloramphenicol ; Cytotoxins ; HeLa Cells ; Humans ; Lethal Dose 50 ; Microbial Sensitivity Tests ; Vibrio vulnificus ; Virulence*

To establish in vivo antiviral evaluation system by using murine herpesvirus intracerebral infection model, 5-6 female BALB/c mice per group aged 5 weeks were inoculated i.c. into cerebrum with different inocular HSV-1 F. Signs of clinical disease noted everyday for one month. Observed were body weight decrease, neurological signs and death caused by encephalitis. Mice discontinued body weight decrease were recovered from the disease, and keratitis was often observed during recovery. The groups inoculated with higher than 1,000 PFU showed 100% mortaltiy and LD50 was <100 PFU/mouse. To study the effect of virus inoculum sizes on antiviral effect of acyclovir (ACV), mice inoculated with different inocula were administered i.p. with different doses of ACV immediately after infection, and twice a day for 5 days. The higher inculum size, the less protective. ED50 of ACV was >25, >25, 18.4 and 8.0mg/kg b.i.d. in the group infected with 1,000,000, 100,000, 10,000 and 1,000 PFU/mouse, respectively. LD50 of ACV was 62.5 mg/kg b.i.d. Therapeutic index of ACV was <2.5, <2.5, 3.0 and 7.0 in the groups with inocula 1,000,000, 100,000, 10,000 and 1,000 PFU/mouse, respectively. Inoculum size 1,000 PFU/mouse showing 100% mortaltiy and 5-6 days mean time to death, 5 days drug administration and 14 days observation will be future exeperimental conditions.
Acyclovir* ; Animals ; Body Weight ; Cerebrum ; Encephalitis ; Female ; Herpesvirus 1, Human ; Humans ; Keratitis ; Lethal Dose 50 ; Mice*

Mice were used to evaluate the adverse testicular effects of anticancer agents. Testicular cytotoxicity of many chemotherapeutic drugs has been evaluated in mice. In this report, we described thio-TEPA induced testicular toxicity in mature male I. C. R. mice. On day o, mice in the treatment groups were given different single intraperitoneal doses of thio-TEPA(0.1 to 25mg/kg). On day 56, all surviving mice were killed and necropsied. Testicular toxicity was evaluated qualitatively by histology and quantitatively by testicular weight(testis weight/body weight), repopulation index and epididymal index. Progressive dose dependent testicular atrophy and oligospermia occurred at low and intermediate doses of thio-TEPA(0.1 to 5mg/kg). Marked testicular atrophy, oligospermia and germinal aplasia were observed at high dose of thio-TEPA(10mg/kg). LD50 for animal mortality at day 56 for thio-TEPA appears to be 25mg/kg. In this report, we described the quantitative relationship between thio-TEPA dosage and testicular cytotoxicity in mature male I. C. R. mice.
Animals ; Antineoplastic Agents ; Atrophy ; Humans ; Lethal Dose 50 ; Male ; Mice* ; Mortality ; Oligospermia ; Testis ; Thiotepa*

BACKGROUND: The current study examined the acute systemic toxicity of QX-314 that there have been few research results for this so far. In order to be useful as a drug, it must be shown to have minimal toxicities. Hence, we compared the CNS and cardiac toxicities of QX-314 to the conventional local anesthetic lidocaine. METHODS: Acute toxicity was evaluated by determining the individual intravenous CD50 and LD50 of QX-314 and lidocaine. There were four doses for each LD50 determination and 8 animals per dose level. Animals were observed for several hours immediately following drug administration and recorded overt effects and fatalities. Both lidocaine and QX-314 were dissolved in saline. Lidocaine and QX-314 were diluted to 1, 2, 4, 6 and 0.5, 1, 2, 4%, respectively with saline and injected at the same volume to minimized cardiovascular effect. RESULTS: The intravenous CD50 and LD50 were 12.7 and 14.1 mg/kg for QX-314 and 15.7 and 28.8 mg/kg for lidocaine. Electrocardiograms showed intraventricular block (widened QRS complex) at high doses of lidocaine compared to AV block (loss of QRS complex) at high concentrations of QX-314. There are no evidence that CNS toxicity led mouse to death. CONCLUSIONS: QX-314 is about 1.5 times as toxic as lidocaine. Although QX-314 may still be useful clinically as a long-lasting local anesthetic, its safety relative to other available local anesthetics must be considered.
Anesthetics, Local ; Animals ; Atrioventricular Block ; Electrocardiography ; Lethal Dose 50 ; Lidocaine ; Mice ; Quaternary Ammonium Compounds

Botulinum neurotoxin type A (BoNT/A) is a metalloprotease that cleaves SNAP-25 (synaptosome-associated protein of 25 kDa), a specific cellular protein essential for neurotransmitter release. As well as mouse bioassay to detect BoNT/A, various assay methods based on its endopeptidase activity have been developed. In this study, we tried to develop a BoNT/A assay system using recombinant SNAP-25 with glutathione S-transferase (GST) tags at both termini as substrate. The recombinant GST-SNAP-25-GST with 70 kDa was expressed and purified in E. coli and synthesized N-terminal 50 kDa and C-terminal 25 kDa fragment after cleavage at the Gln(197)-Arg(198) bond by BoNT/A. To detect both fragments, we obtained rabbit antisera against peptides corresponding to the cleaved ends of each fragment. In the western blotting, the N-terminal fragment was detected by the antibody specifically recognizing the newly exposed C-terminus (corresponding to amino acid residue 191-197). This assay system was able to detect until 3.125 ng of BoNT/A, which corresponded to about 90 fold LD50 in mice. These results suggest that the in vitro endopeptidase assay developed in this study would replace others to detect BoNT/A.
Animals ; Biological Assay ; Blotting, Western ; Glutathione Transferase ; Immune Sera ; Lethal Dose 50 ; Mice ; Neurotransmitter Agents ; Peptides

Botulinum neurotoxin type A (BoNT/A) is a metalloprotease that cleaves SNAP-25 (synaptosome-associated protein of 25 kDa), a specific cellular protein essential for neurotransmitter release. As well as mouse bioassay to detect BoNT/A, various assay methods based on its endopeptidase activity have been developed. In this study, we tried to develop a BoNT/A assay system using recombinant SNAP-25 with glutathione S-transferase (GST) tags at both termini as substrate. The recombinant GST-SNAP-25-GST with 70 kDa was expressed and purified in E. coli and synthesized N-terminal 50 kDa and C-terminal 25 kDa fragment after cleavage at the Gln(197)-Arg(198) bond by BoNT/A. To detect both fragments, we obtained rabbit antisera against peptides corresponding to the cleaved ends of each fragment. In the western blotting, the N-terminal fragment was detected by the antibody specifically recognizing the newly exposed C-terminus (corresponding to amino acid residue 191-197). This assay system was able to detect until 3.125 ng of BoNT/A, which corresponded to about 90 fold LD50 in mice. These results suggest that the in vitro endopeptidase assay developed in this study would replace others to detect BoNT/A.
Animals ; Biological Assay ; Blotting, Western ; Glutathione Transferase ; Immune Sera ; Lethal Dose 50 ; Mice ; Neurotransmitter Agents ; Peptides