Gamma (60)Co DL(50/30) of Biomphalaria glabrata (SAY, 1818).
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The variation of resistance to (60)Co gamma-rays of Biomphalaria glabrata was studied. A population of 480 mollusks was observed during 30 days - distributed in 8 groups of snails isolated and 8 groups of snails in colonies - after exposure (30 snails per group per dose) to increasing doses of gamma radiation. Doses of 10, 20, 40, 60, 80, 160, 320 and 640 Gy from a Gamma-cell (60)Co irradiator, were applied to the test groups and two groups control (non-irradiated) of snails - isolated and colony - were kept apart. After have been exposed, the snails were drew back to the aquaria where they were maintained before. The survival was estimated on a daily score of the alive animals in each group-dose, starting after the irradiation exposure day. As a result, the survival self-fertilization forms (DL(50/30) = 218.2 Gy) was found greater than in cross-fecundation forms. These data point to a low radio-resistance on the cross-fertilization forms - the sexual reproductive form - which is most found in nature. The lower radio-resistance of the cross-fertilization forms suggests the presence of some sex-linked hormonal factor related to this phenomenon. (+info)
Induction of apoptotic cell death and in vivo growth inhibition of human cancer cells by a saturated branched-chain fatty acid, 13-methyltetradecanoic acid.
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A saturated branched-chain fatty acid, 13-methyltetradecanoic acid (13-MTD), was purified from a soy fermentation product, which was used by many cancer patients as a treatment supplement. Our preliminary study indicated that 13-MTD could induce cell death in human cancer cell lines K-562, MCF7, DU 145, NCI-SNU-1, SNU-423, NCI-H1688, BxPC3, and HCT 116. The ID50 dosage of 13-MTD for these tumor cells ranged from 10 to 25 microg/ml. Further investigation revealed that 13-MTD caused tumor cell death through rapid induction of apoptosis, which could be detected 2 h after the treatment of tumor cells with 13-MTD. Xenograft tumors of prostate carcinoma cell line DU 145 and hepatocarcinoma LCI-D35 were orthotopically implanted into nude mouse prostate and liver, respectively. 13-MTD was administered p.o. once daily to the implanted mice for approximately 40 days. Our results showed that 13-MTD could effectively inhibit the growth of orthotopic tumor implants of both cell lines compared with control groups. The average inhibition rate was 84.6% for DU 145 and 65.2% for LCI-D35 (P < 0.01). LD50 test results showed that mice could well sustain the oral feeding of 5 g/kg/day without observable anomaly. Our preliminary data demonstrated that 13-MTD could effectively inhibit in vitro and in vivo growth of various cancer cell lines by inducing apoptosis without significant toxic side effects, suggesting 13-MTD as a potential candidate for chemotherapy of human cancers. (+info)
Differences of susceptibility of five triatomine species to pyrethroid insecticides - implications for Chagas disease vector control.
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As pyrethroids are presently the favored group of insecticides to control triatomines, we performed a series of bioassays to determine the intrinsic activity of some of the main compounds used in the control campaigns, against five of the main species of triatomines to be controlled. Comparing the insecticides it can be seen that lambdacyhalothrin is more effective than the other three pyrethroids, both considering the LD50 and 99 for all the three species with comparable results. On Triatoma infestans the LD50 of lambdacyhalothrin was followed by that of alfacypermethrin, cyfluthrin and deltamethrin. On Rhodnius prolixus the sequence, in decreasing order of activity, was lambdacyhalothrin, alfacypermethrin, deltamethrin and cyfluthrin. Some modifications can be seen when we compare the LD99, that has more to see to what happens in the field. T. brasiliensis showed to be as sensible to lambdacyhalothrin as T. infestans, the most susceptible for this product. By the other side T. sordida is the least susceptible considering the LD99 of this insecticide. (+info)
Systemic anti-inflammation by synthetic interleukin-1 blockers.
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AIM: To study the systemic anti-inflammatory actions of interleukin-1 (IL-1) blockers, OB-101 and OB-186. METHODS: Prevention of palm swelling induced by carrageenin injection was used as an animal model of systemic anti-inflammation efficacy. RESULTS: Both OB-101 and OB-186 (10-30 mg.kg-1) were approximately 10-30-fold more potent than aspirin (300 mg.kg-1) to inhibit carrageenin-induced systemic inflammation. The LD50 of OB-101 and OB-186 were at least 20 g.kg-1 i.g., indicating that they were extremely safe agents with a therapeutic index (LD50/ED50) of at least 2000. CONCLUSION: These IL-1 blockers are extremely safe systemically and are useable for the treatment of systemic inflammation such as rheumatoid arthritis. (+info)
Infectious necrotizing enteritis and mortality caused by Vibrio carchariae in summer flounder Paralichthys dentatus during intensive culture.
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An epizootic causing mortality among cultured summer flounder Paralichthys dentatus occurred in summer of 1998 at a land-based facility on Narragansett Bay, Rhode Island, USA. The disease, flounder infectious necrotizing enteritis (FINE), was characterized by reddening around the anal area, distended abdomens filled with opaque serosanguineous fluid, enteritis and necrosis of the posterior intestine. In extreme cases of the disease, the posterior intestine was detached from the anus and was observed coming out the vent. The intestine of individuals that recovered from the disease ended in a blind-sac; the abdomens of these fish were distended, due to food and water inside the intestinal blind-sac. A bacterium was isolated from ascites fluid and kidney of moribund flounder and identified as the causative agent in challenge experiments. The pathogen was identified as Vibrio carchariae by morphological and biochemical characteristics and sequence of the 16S rRNA. The LD50 estimate was 5 x 10(5) colony-forming units injected intraperitoneally into 100 to 200 g summer flounder. (+info)
In vivo acetylcholinesterase inhibition, metabolism, and toxicokinetics of aldicarb in channel catfish: role of biotransformation in acute toxicity.
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The carbamate pesticide, aldicarb, demonstrates significant acute toxicity in mammals, birds, and fish through the inhibition of acetylcholinesterase (AChE), and may present high potential for exposure of aquatic organisms during periods of runoff. Toxicity studies have shown that channel catfish are less sensitive to the acute toxic effects of aldicarb than are rainbow trout or bluegill. An earlier in vitro study suggests that the aldicarb resistance in catfish may be related to a low level of bioactivation to the potent aldicarb sulfoxide. The current study examines the toxicity, AChE inhibition, plasma kinetics, and in vivo metabolism of aldicarb in channel catfish. A 48-h LC50 of 9.7 mg/l was determined for juvenile channel catfish. Mortality was accompanied by dramatic loss of brain AChE. Further characterization of tissue-level effects suggests that muscle AChE plays a causal role in mortality. Aldicarb was metabolized in channel catfish to aldicarb sulfoxide, along with the formation of minor hydrolytic products. The toxicokinetics of aldicarb in catfish are bi-compartmental with rapid elimination (t1/2 = 1.9 h). Plasma AChE was inhibited in a pattern similar to that of the elimination of total aldicarb-derived compounds. A comparison of aldicarb uptake between catfish and rainbow trout showed no difference in compound absorbed in 24 h. The pattern of in vivo metabolism, however, was quite different between these species. Rainbow trout produce significantly more hydrolytic derivatives and have a 3-fold higher aldicarb sulfoxide to aldicarb ratio at 3 h. These data give strength to the hypothesis that a slower rate of bioactivation in the catfish (vs. rainbow trout) is acting as a protective mechanism against the acute toxicity of aldicarb. (+info)
Okaramines N, O, P, Q and R, new okaramine congeners, from Penicillium simplicissimum ATCC 90288.
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Five new okaramine congeners, okaramines N, O, P, Q, and R, were isolated from Penicillium simplicissimum ATCC 90288. Their structures were determined by an analysis of spectroscopic data. The insecticidal activity of these new okaramines was evaluated against silkworms. (+info)
Chemical synthesis and characterization of maurocalcine, a scorpion toxin that activates Ca(2+) release channel/ryanodine receptors.
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Maurocalcine is a novel toxin isolated from the venom of the chactid scorpion Scorpio maurus palmatus. It is a 33-mer basic peptide cross-linked by three disulfide bridges, which shares 82% sequence identity with imperatoxin A, a scorpion toxin from the venom of Pandinus imperator. Maurocalcine is peculiar in terms of structural properties since it does not possess any consensus motif reported so far in other scorpion toxins. Due to its low concentration in venom (0.5% of the proteins), maurocalcine was chemically synthesized by means of an optimized solid-phase method, and purified after folding/oxidation by using both C18 reversed-phase and ion exchange high-pressure liquid chromatographies. The synthetic product (sMCa) was characterized. The half-cystine pairing pattern of sMCa was identified by enzyme-based cleavage and Edman sequencing. The pairings were Cys3-Cys17, Cys10-Cys21, and Cys16-Cys32. In vivo, the sMCa was lethal to mice following intracerebroventricular inoculation (LD(50), 20 microg/mouse). In vitro, electrophysiological experiments based on recordings of single channels incorporated into planar lipid bilayers showed that sMCa potently and reversibly modifies channel gating behavior of the type 1 ryanodine receptor by inducing prominent subconductance behavior. (+info)