Effect of L-carnitine against acute mitoxantrone toxicity in mice

Various experiments were performed in our laboratory to define a possible role for carnitine derivatives in mitoxantrone (MX) therapy. We report here the results of the effect of L-carnitine (LCAR) on the lethal toxicity of MX in mice. MX was administered intravenously at doses of 7, 9, 11, 13, 15 or 17 mg kg⁻¹ either alone or in combination with LCAR at a single intravenous dose of 200 mg kg⁻¹. The dependence of the probability of death on various doses was evaluated for the MX-LCAR combination compared to MX alone. From these experiments, the following lethal dose fifty (LD₅₀) values were calculated: LD₅₀ for MX alone was 15.2 mg kg⁻¹, whereas in combination with LCAR it increases to 21.8 mg kg⁻¹. The relative toxicity given as the ratio of the LD50 of both MX alone and the combination of MX-LCAR was 69.7%. The results of our experiments unequivocally show the effect of LCAR on acute toxic doses of MX.     

Chick embryo chorioallantoic membrane (CAM): an alternative predictive model in acute toxicological studies for anti-cancer drugs

The chick embryo chorioallantoic membrane (CAM) is a preclinical model widely used forvascular and anti-vascular effects of therapeutic agents in vivo. In thisstudy, we examine the suitability of CAM as a predictive model for acute toxicologystudies of drugs by comparing it to conventional mouse and rat models for 10 FDA-approvedanticancer drugs (paclitaxel, carmustine, camptothecin, cyclophosphamide, vincristine,cisplatin, aloin, mitomycin C, actinomycin-D, melphalan). Suitable formulations forintravenous administration were determined before the average of median lethal dose(LD₅₀) and median survival dose (SD₅₀) in the CAM were measuredand calculated for these drugs. The resultant ideal LD₅₀ values were correlatedto those reported in the literature using Pearson’s correlation test for both intravenousand intraperitoneal routes of injection in rodents. Our results showed moderatecorrelations (r²=0.42 − 0.68, P<0.005–0.05) between theideal LD₅₀ values obtained using the CAM model with LD₅₀ values frommice and rats models for both intravenous and intraperitoneal administrations, suggestingthat the chick embryo may be a suitable alternative model for acute drug toxicityscreening before embarking on full toxicological investigations in rodents in developmentof anticancer drugs.     

Characterization of a toxin fromParthenium hysterophorus and its mode of excretion in animals

Fractionation of methanolic extracts of air dried aerial parts ofParthenium resulted in the isolation of a toxic constituent which was identified as parthenin, the major sesquiterpene lactone from the weed. The LD₅₀ (minimal lethal dose required to cause 50% mortality) for parthenin in rats was 42 mg/kg body weight. When [³H]-parthenin was given orally or by intravenous administration, radioactivity appeared in the milk of lactating laboratory and dairy animals. Tissue distribution of radioactivity revealed that maximum label was detectable in kidneys.     

牛磺胆酸钠在大鼠急性胰腺炎模型中的半数致死量(LD50)研究

目的:通过使用不同浓度的牛磺胆酸钠(TC)建立急性胰腺炎(AP)模型,观察相应的死亡率,进而计算其半数致死量。方法:使用不同浓度的TC(0%(wt/vl)、1%、2%、3%、4%、5%、9%)观察AP造模72小时后各组的死亡率。同时分析TC浓度与组织病理评分、血清淀粉酶和外周血细胞变化的相关性。结果:TC的半数致死量为3.409%。并且,TC的浓度与组织病理评分、血清淀粉酶和外周血细胞变化密切相关。结论:TC所致AP造模的最佳剂量为3.409%。     

Antimicrobial-immunomodulatory activities of zebrafish phosvitin-derived peptide Pt5

A phosvitin (Pv)-derived peptide, Pt5, which consists of the C-terminal 55 residues of Pv in zebrafish, has been shown to function as an antimicrobial agent capable of killing microbes in vitro. However, its in vivo role in zebrafish remains unknown. In this study, we clearly demonstrated that Pt5 protected adult zebrafish from pathogenic Aeromonas hydrophila attack, capable of significantly enhancing the survival rate of zebrafish after the pathogenic challenge. Pt5 also caused a marked decrease in the numbers of A. hydrophila in the blood, spleen, kidney, liver and muscle, suggesting that Pt5 was able to block multiplication/dissemination of A. hydrophila in zebrafish. Additionally, Pt5 markedly suppressed the expression of the proinflammatory cytokine genes IL-1β, IL-6, TNF-α and IFN-γ in the spleen and head kidney of A. hydrophila-infected zebrafish, but it considerably enhanced the expressions of the antiinflammatory cytokine genes IL-10 and IL-4 in the same tissues. Taken together, these data indicate that Pt5 plays a dual role in zebrafish as an antimicrobial and immunomodulatory agent, capable of protecting zebrafish against pathogenic A. hydrophila through its antimicrobial activity as well as preventing zebrafish from the detrimental effects of an excessive inflammatory response via modulating immune functions.     

原矛头蝮蛇毒毒性及恢复规律

目的:对原矛头蝮(P.mucrosquamatus)的毒性及其恢复规律进行考察,增进对该蛇毒性的认识。方法:用该蛇连续攻击小鼠,用梯度剂量蛇毒对小鼠进行腹腔注射,统计死亡率,以折算绝对毒性和半数致死量。对毒性耗竭个体,在梯度时间间隔采集蛇毒,以考察毒性恢复规律。结果:原矛头蝮在2 h内可导致6只小鼠死亡。蛇毒对小鼠的半数致死量为12.204μL/Kg。毒性耗竭后,在间隔21天所获得蛇毒的容积达到最大值即190μL,湿重为149.7 mg。结论:毒蛇在攻击猎物时,并不一次性排完毒腺中的所有毒液,随着攻击次数的增多,毒腺中毒液量逐步减少直至耗竭。其毒液量的恢复需要约3周时间,期间,单次排毒量逐渐增加,干物质的含量也基本呈递增趋势。就单次最大排毒量而言,原矛头蝮高于竹叶青、蝮蛇和银环蛇。其单位剂量毒性高于五步蛇和竹叶青。     

Identification and characterization of a taxon-specific three-finger toxin from the venom of the Green Vinesnake (Oxybelis fulgidus; family Colubridae)

Snake venoms contain a variety of protein and peptide toxins, and the three-finger toxins (3FTxs) are among the best characterized family of venom proteins. The compact nature and highly conserved molecular fold of 3FTxs, together with their abundance in many venoms, has contributed to their utility in structure-function studies. Although many target the nicotinic acetylcholine receptor of vertebrate skeletal muscle, often binding with nanomolar K_ds, several non-conventional 3FTxs show pronounced taxon-specific neurotoxic effects. Here we describe the purification and characterization of fulgimotoxin, a monomeric 3FTx from the venom of Oxybelis fulgidus, a neotropical rear-fanged snake. Fulgimotoxin retains the canonical 5 disulfides of the non-conventional 3FTxs and is highly neurotoxic to lizards; however, mice are unaffected, demonstrating that this toxin is taxon-specific in its effects. Analysis of structural features of fulgimotoxin and other colubrid venom 3FTxs indicate the presence of a “colubrid toxin motif” (CYTLY) and a second conserved segment (WAVK) found in Boiga and Oxybelis taxon-specific 3FTxs, both in loop II. Because specific residues in loop II conventional α-neurotoxic 3FTxs are intimately associated with receptor binding, we hypothesize that this loop, with its highly conserved substitutions, confers taxon-specific neurotoxicity. These findings underscore the importance of rear-fanged snake venoms for understanding the evolution of toxin molecules and demonstrate that even among well-characterized toxin families, novel structural and functional motifs may be found.     

Probability of freezing in the freeze-avoiding beetle larvae Cucujus clavipes puniceus (Coleoptera: Cucujidae) from interior Alaska

Freeze-avoiding insects must resist freezing or die. A suite of adaptations to low temperatures, including the production of antifreeze proteins, colligative antifreezes (polyols), and dehydration allows most individuals to prevent freezing below the lowest ambient temperatures experienced in situ; however, there can be a wide variance in the minimum temperatures that individuals of freeze-avoiding species reach before freezing. We used logistic regression to explore factors that affect this variance and to estimate the probability of freezing in larvae of the freeze-avoiding beetle Cucujus clavipes puniceus. We hypothesized that water content ≤ 0.5 mg mg⁻¹ dry mass would lead to deep supercooling (avoidance of freezing below −58 °C). We found a significant interaction between water content and ambient below-snow temperature and a significant difference between individuals collected from two locations in Alaska: Wiseman and Fairbanks. Individuals collected in Wiseman deep supercooled with greater water content and to a greater range of ambient temperatures than individuals collected in Fairbanks, leading to significantly different lethal water contents associated with 50% probability of freezing.     

Genetic characterization of Listeria monocytogenes food isolates and pathogenic potential within serovars 1/2a and 1/2b

A total of 39 Listeria monocytogenes strains isolated from raw milk, smoked meat, chicken carcass and reference strains, belonging to serovars 1/2a, 4a, 1/2b, 3b and 4b, were analysed by RAPD and by polymorphisms of the virulent genes inlAB and iap. Ten isolates, belonging to serovars 1/2a and 1/2b and, collected from raw milk and smoked meat, were further tested for pathogenicity by IP injection into mice. The clustering of the 39 L. monocytogenes strains in 3 groups at 0.45 similarity level, based on molecular typing, was observed. Distribution of serovars in these clusters was in agreement with the proposed three Listeria monocytogenes lineages. Within serovar 1/2b, the 50% lethal dose (LD50) ranged from 8.4 x 10(4) to 1.7 x 10(6) cfu.ml(-1). One of the serovar 1/2b strains, isolated from smoked meat, exhibited the lowest virulence potential evaluated by LD50 and by mean time to death (MTD) and, from this point of view, was completely different from the other strains. Our results suggest the existence of heterogeneity in virulence levels within serovars 1/2a and 1/2b. However, when comparing the isolates based on genotyping, virulence indicators and food origin, no relation could be assessed.     

球孢白僵菌九个菌株对赤拟谷盗成虫的毒效（英文）

球孢白僵菌Beauveria bassiana (Balsamo) Vuillemin是最重要的昆虫病原真菌, 广泛用于防治世界各地的多种害虫。本研究评价了球孢白僵菌9个菌株对赤拟谷盗Tribolium castaneum (Herbst)成虫的致病性。将15头赤拟谷盗成虫浸入到4个浓度 (1×10⁶, 1×10⁷, 1×10⁸ 和 1×10⁹ 个分生孢子/mL)的白僵菌菌株中 20 s, 14 d内每日记录成虫的死亡率。结果表明： IRAN 440C菌株对赤拟谷盗成虫的LC₅₀最低 (5.04×10⁷ 个分生孢子/mL), IRAN 187C菌株的最高(5.05×10⁸ 个分生孢子/mL); DEBI 005菌株对赤拟谷盗成虫的LT₅₀最短(2.88 d), DEBI 014菌株的最长(4.96 d)。根据LC₅₀, LT₅₀和死亡率结果得出IRAN 440C是防治这一害虫的理想菌株。     

X-ray irradiation of excised embryos of mesta (Hibiscus cannabinus L. and H. sabdariffa L.)

Summary Excised embryos of Hibiscus spp. were treated with 1 kR to 6 kR of X-ray. Results indicate that germination was unaffected at this level of employed doses in both species, which in turn implies that the factors responsible for inhibition of germination are not present in the embryo. LD₅₀ values differed between varieties and species. Early varieties of both species were more sensitive to radiation than late varieties. Strikingly similar effects were observed for the varieties with smaller embryos over those with larger ones. Allopolyploid H. sabdariffa (2n=72) was more susceptible than diploid H. cannabinus (2n=36).Differences in mutation frequency exist between species with different levels of ploidy and between varieties within the same species. Most of the HC mesta varieties yielded higher mutation frequencies than those of HS mesta. Optimal dose for triggering mutations in all varieties (except the chlorophyll mutation variety of HC mesta) of the two species lies within a narrow range of 1 kR to 2 kR. Cent per cent seedling abnormalities is concomitant to LD₅₀; nevertheless, optimum dose for mutation frequency is independent of LD₅₀. Hence, the response should be viewed in terms of respective genotype. The advantages of the embryo irradiation technique are mentioned.     

昆虫病原真菌与硅藻土混用对四纹豆象的毒力效果(英文)

在室内条件下检测了白僵菌Beauveria bassiana (Balsamo) Vuillemin 菌株IRAN-187C 和金龟子绿僵菌Metarhizium anisopliae (Metschnikow) Sorokin菌株A-396分别与硅藻土（DE）制剂InsectoSec混用对四纹豆象Callosobruchus maculatus成虫的毒力效果。结果表明：硅藻土与致死剂量和亚致死剂量的真菌分离物混用导致了四纹豆象成虫的高死亡率,且这些处理均缩短了真菌的致死中时(LT₅₀)。LC₅₀ 的白僵菌B. bassiana菌株IRAN-187C和 LC₅₀ 的DE混用对四纹豆象的LT₅₀ (122.2 h)最低,在95%置信限上与LC50 的金龟子绿僵菌M. anisopliae菌株A-396 与LC₅₀的DE混用得到的LT₅₀ (128.2 h) 相当,说明两种真菌分离物与DE混用对四纹豆象成虫都具有较好的毒力效果。用四纹豆象成虫检测3个温度（22, 27和30℃）和2个相对湿度（40%和55%）组合对DE活性的影响,结果显示30℃和40%相对湿度条件下得到的LT₅₀ (110.11 h)最低,说明高温低湿条件下DE活性较高。     

Possible recovery from an acute envenomation in male rats with LD50 of Echis coloratus crude venom: I-A seven days hematological follow-up study

The effect of an acute LD₅₀ dose of Echis coloratus crude venom in male albino rats was tested on blood parameters: white blood cells (WBCs), red blood cells (RBCs), platelets count, hemoglobin, hematocrit, mean cell volume (MCV), mean cell hemoglobin (MCH) and mean cell hemoglobin concentration (MCHC), also serum glucose, total protein, triglycerides with alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP) and γ-glutamyl transferase (GGT) enzyme activities. The effect of the LD₅₀ dose was monitored over a period of seven days, with time intervals of 1, 3, 6, 12, 24, 72 h. All of the tested parameters show fluctuations with time and with tendency to regain normal control level after 12 h. At 12–24 h it seems to be crucial for the process of physiological recovery, in spite of the irreversible damage and tissue distraction. The process of physiological adaptation and recovery from the lethal destructive venom effect seems to stabilize after one week, leaving the animal alive with several biochemical altered metabolisms and disturbed physiological profile.     

Role of glutamine-169 in the substrate recognition of human aminopeptidase B

Background

Aminopeptidase B (EC 3.4.11.6, APB) preferentially hydrolyzes N-terminal basic amino acids of synthetic and peptide substrates. APB is involved in the production and maturation of peptide hormones and neurotransmitters such as miniglucagon, cholecystokinin and enkephalin by cleaving N-terminal basic amino acids in extended precursor proteins. Therefore, the specificity for basic amino acids is crucial for the biological function of APB.

Methods

Site-directed mutagenesis and molecular modeling of the S1 site were used to identify amino acid residues of the human APB responsible for the basic amino acid preference and enzymatic efficiency.

Results

Substitution of Gln169 with Asn caused a significant decrease in hydrolytic activity toward the fluorescent substrate Lys-4-methylcoumaryl-7-amide (MCA). Substantial retardation of enzyme activity was observed toward Arg-MCA and substitution with Glu caused complete loss of enzymatic activity of APB. Substitution with Asn led to an increase in IC₅₀ values of inhibitors that interact with the catalytic pocket of APB. The EC₅₀ value of chloride ion binding was also found to increase with the Asn mutant. Gln169 was required for maximal cleavage of the peptide substrates. Molecular modeling suggested that interaction of Gln169 with the N-terminal Arg residue of the substrate could be bridged by a chloride anion.

Conclusion

Gln169 is crucial for obtaining optimal enzymatic activity and the unique basic amino acid preference of APB via maintaining the appropriate catalytic pocket structure and thus for its function as a processing enzyme of peptide hormones and neurotransmitters.     

30种植物杀鼠活性研究

采用饲料混毒法测定了30种植物的杀鼠活性,用灌胃法测定了4种植物的毒性,并对2种植物中的活性成分进行了分离.结果表明苦参、曼陀罗、牛皮消、牛心朴、铁棒锤、皂荚、黄花烟草、接骨木、乌头、大戟、宽裂乌头、野八角、短柄乌头、贯众、瑞香狼毒在饵料中添加量为20%时,试鼠死亡率均在50%以上.曼陀罗、皂荚、乌头、大戟对试鼠的致死中量(LD50)分别为7.04、2.21(皂荚乙醇提取液)和3.52(皂荚丙酮提取液)、10.67和19.56 g·kg-1.同时从苦参、曼陀罗中分离出了8种单体化合物,其中7种具有较好的杀鼠活性,5种杀鼠效果显著.     

Liposome-based formulations for the antibiotic nonapeptide Leucinostatin A: Fourier transform infrared spectroscopy characterization and in vivo toxicologic study

Leucinostatin-A is a nonapeptide isolated fromPaecilomyces marquandii Paecilomyces lilacinus A257, andAcremonium sp., exerting remarkable phytotoxic, antibacterial (especially against Gram-positive) and antimycotic activities. With the aim to find alternative formulation for in vivo administration, a number of Leucinostatin-A—loaded liposomal formulations have been prepared and characterized. Both large unilamellar vesicles and multilamellar vesicles consisting of synthetic and natural lipids were evaluated. In addition, to determine the nature of peptide-membrane interactions and the stability of liposomes loaded with Leucinostatin-A, a Fourier Transform Infrared Spectroscopy study was performed. The results suggest that the mode of interaction of the peptide is dependent on its concentration, on bilayer fluidity, and on liposome type. Finally, the LD₅₀ of both free and liposome-delivered Leucinostatin-A was determined in mice. These results suggest that the incorporation of Leucinostatin-A into liposomes may result in decreased Leucinostatin-A toxicity, as the intraperitoneal administration of Leucinostatin-A—loaded liposomes reduced the LD₅₀ of Leucinostatin-A 15-fold.     

东亚钳蝎粗毒蛋白质热稳定性的研究

目的:通过蝎毒热溶解性和毒性实验,探索蝎毒蛋白稳定性与分子量间的关系。方法:对蝎毒粗毒煮沸后的可溶成分进行急性毒力实验和SDS-PAGE电泳分析。结果:蝎毒粗毒加热处理组的LD50为16.228mg/kg,粗毒对照组的LD50为3.66mg/kg,显示蝎毒经加热后毒力明显降低,但仍具有一定的毒性。SDS-PAGE结果显示,经加热处理的粗蝎毒之沉淀主要为大分子蛋白质,在可溶成分中含有小分子肽类。结论:蝎毒的大分子蛋白质热稳定性差,而小分子多肽部分耐热性强,而且蝎毒的小分子多肽组分具有相对稳定的毒性。     

Acute toxicity of Cd in stream invertebrates in relation to pH and test design

The acute toxicity of Cd to three stream invertebrates (Baetis rhodani Pict., Leptophlebia marginata (L.) and Pisidium sp.) was tested at pH 5 and 7 simultaneously in static (ST) and flow through (FT) systems. In the static design, the animals were kept individually in small boxes containing aerated stream water. In the flow through system, the three species were kept together in circular aquaria simulating stream ecosystems with patches of gravel and recirculating aerated stream water. The nominal Cd concentrations ranged from 0 to 5 mg 1^–1 during an exposure period of 120 h.The graphically obtained LC₅₀ (120 h) values for B. rhodani were: pH 7: 2.3 mg 1^–1 (ST), 2.5 mg 1^–1 (FT) and pH 5: 3 mg 1^–1 (ST), 1 mg 1^–1 (FT). For L. marginata the following values were found: pH 7: > 5 mg 1^–1 (ST), 4.4 mg 1^–1 (FT) and pH 5: > 5 mg 1^–1 (ST), 3.6 mg 1^–1 (FT). Pisidium sp. showed a 100% survival in all Cd- and pH-treatments. From thee values it can be concluded that L. marginata is more tolerant than B. rhodani and that especially both species tolerated Cd better in the ST system than in the FT system, especially at pH 5.At neutral pH the Cd-concentrations in the animals were higher than at low pH, probably due to surface adsorption of Cd onto the body. B. rhodani tended to molt more at low than at neutral pH.