Genetic effects induced by nickel sulfate in germline and somatic cells of WR mice

We examined the effects of nickel sulfate at doses 0.5 to 5.0 mg/kg (LD50) on the frequency of dominant lethal mutations and two-strand DNA breaks (TSBs) in germline cells and on an increase in frequency in gene mutations W(y) in pigment cells of first-generation mice. The results indicated that spermatogenesis stages most sensitive to nickel sulfate (at a dose of 1.0 mg/kg) are spermatozoids, early spermatids, late spermatocytes, and stem spermatogonia. No statistically significant increase in the total TSB level was detected in spermatozoids 4 weeks after exposure. At the same time, a significant (P < 0.05) increase in percentage of cells with an extremely high level of DNA fragmentation (supposedly apoptotic cells) was observed upon exposure at a dose of 0.5 mg/kg. Nickel sulfate at doses of 5.0 and 1.0 mg/kg induced a marked increase in the c-kit gene expression in pigment cells of heterozygous first-generation WR mice as compared to control (P < 0.001). It was shown that the nonobservable adverse effect level (NOAEL) of nickel sulfate on the dominant lethal mutation frequency and gene mutations was 1/200 LD50, while the lowest observable adverse effect level (LOAEL) was 1/100 LD50.     

The mutagenicity of hydrazine and some of its derivatives.

The mutagenic effect of ethylenethiourea (ETU), a degradation product and metabolite of ethylenebisdithiocarbamates, which are widely used as fungicides, was studied in different test systems.ETU induced mutations of the base-pair substitution type in Salmonella typhimurium TA 1530 in vitro as well as in the host-mediated assay. In the host-mediated assay, a dose of 6000 mg/kg (LD₅₀ = 5400 mg/kg) resulted in a slight but significant increase of the reversion frequency by a factor of 2.37.The results of the micronucleus test were negative after two-fold oral applications of 700, 1850 and 6000 mg/kg to Swiss albino mice. Thus it is concluded that ETU hardly induces any chromosomal anomality in the bone marrow.No dominant-lethal effect was observed after single oral doses of 500, 1000 and 3500 mg/kg given to male mice.     

Studies on the Utilization of Levulinic Acid

The single injection of levulinic acid oxime (250 mg/rat) or α-ketoglutaric acid oxime (250 mg/rat) on rats, carrying radioactive cesium, promoted both urinary and fecal excretion of this radionuclide. The administration of levulinic acid oxime (sodium salt) decreased the cesium retention by liver. The administration of the oxime did not have influence on the urinary excretion of sodium and potassium in normal rats. The toxicity of the oxime was low. The LD₅₀ of α-ketoglutaric acid oxime was 3500 mg/kg (mice, intraperitoneally). (The LD₅₀ of levulinic acid oxime has already been indicated as 2040 mg/kg (mice, intravenously).     

Lethal Effect of Neutral Mannan Fraction of Bakers' Yeast in Mice

A simple polysaccharide, the neutral mannan from Saccharomyces cerevisiae wild type strain (WNM) was found to kill ddY strain mice by intravenous administration, showing a LD₅₀ value of 12.2 mg/kg. On the other hand, the acidic mannan fraction from the same yeast containing phosphate (WAM025), and chemically phosphorylated WNM (WNM-P) were practically non-toxic. Concerning the relationship between chemical structure and lethal effect of these mannans, it was demonstrated that a mannan possessing a highly branched structure exhibited stronger lethality than those with less branched structures. Against C3H/HeJ strain mice with no responsiveness to lipopolysaccharide, the LD₅₀ value of WNM was as high as 75 mg/kg. Pretreatment with 500 mg/kg of D-mannose, N-acetyl-D-glucosamine, D-galactose, and L-fucose prevented mice from the lethal effects of WNM. However, WNM (LD₁₀₀) did not show any lethal effect in mice for 2 to 12 hr after treatment with dexamethasone, an anti-inflammatory steroid.     

Toxic Blue-green Algae Water Blooms Found in some Lakes in the German Democratic Republic

From 1977 to 1979 plankton samples were taken from 6 lakes in the German Democratic Republic (GDR) during water blooms and examined for their toxicity to homothermal animals. Microcystis aeruginosa, Aphanizomenon flos-aquae, Anabaena spiroides, and Oscillatoria redekei were dominant in the samples. With the exception of Oscillatoria redekei the algae tested had toxic effects on mice after intraperitoneal injection. The rate of survival of the test animals was particularly low when the algae were disintegrated by ultrasound or freeze-drying prior to injection, this indicating the endogenic character of the toxins. Water blooms of Microcystis aeruginosa taken from Lake Pehlitzsee (Eberswalde District) showed the highest toxicity with an LD₃₀ as high as 45 and 43.7 mg/kg, respectively. Injection of the lyophilized cells of Aphanizomenon flos-aquae brought about the same symptoms in the test animals as in the case of Microcystis, but the LD₃₀ was 200 mg/kg.     

FACTORS INFLUENCING THE TOXICITY AND ANIMAL SUSCEPTIBILITY OF ANABAENA FLOS-AQUAE (CYANOPHYTA) BLOOMS1

Biological factors have been found which can cause variable toxicity of colony and clonal isolates of Anabaena flos-aquae (Lyngb.) de Bréb. when cultured in the laboratory. These factors help to explain some of the variable toxicity of and animal susceptibility to A. flos-aquae blooms in nature. Two bacteria in the Enterobacteriaceae isolated from a toxic waterbloom, depressed toxin production in selected bacteria-free toxic clones of A. flos-aquae. These toxin-depressing bacteria decreased culture toxicity 3-fold from 80 to 240 mg/kg (intra-peritoneal in male mice). Many colony isolates from a toxic bloom had minimum lethal dosages (LD_min) greater than 240 mg/kg. This was because they were composed of mixtures of toxic and nontoxic filaments. The oral LD_min of the toxin from A. flos-aquae clonal isolate NRC-44-1 varied significantly for 6 different animal species. Using these oral LD_min it is estimated that a surface-concentrated bloom of toxic A. flos-aquae, having a biomass density of 20 mg/ml dry weight, would cause death of ducks or calves when 20 ml/kg was consumed whereas a monogastric animal such as a rat would require 80 ml/kg.     

Primary poisoning risk for encapsulated sodium nitrite,a new tool for pest control

ABSTRACT

Acute toxicity of sodium nitrite (NaNO₂) was assessed in chickens (Gallus gallus domesticus) and domestic mallard ducks (Anas platyrhynchos domestica) by oral gavage and in free-feeding trials with chickens, domestic mallard ducks, pigeons (Columba livia f. domestica), budgerigars (Melopsittacus undulates) and wētā (Family: Rhaphidophoridae). Free-feeding trials involved the presentation of toxic paste and pellet baits containing encapsulated NaNO₂ developed for the control of common brushtail possums (Trichosurus vulpecula) and feral pigs (Sus scrofa). The oral gavage LD₅₀ value for NaNO₂ in solution was approximately 68.50?mg/kg (95% CI 55.00–80.00?mg/kg) for both chickens and ducks. In feeding trials, six out of 12 chickens consumed toxic paste bait and four of these birds consumed a lethal dose. When chickens consumed toxic paste bait, the LD₅₀ value was approximately 254.6?mg/kg (95% CI 249.1–260.2?mg/kg). Of the other three species of birds presented with toxic baits only one duck consumed a lethal dose of paste bait. There was no evidence of wētā feeding on toxic baits.     

Efficacy and safety of catnip (Nepeta cataria) as a novel filth fly repellent*

Catnip (Nepeta cataria) is known for its pseudo‐narcotic effects on cats. Recently, it has been reported as an effective mosquito repellent against several Aedes and Culex species, both topically and spatially. Our laboratory bioassays showed that catnip essential oil (at a dosage of 20 mg) resulted in average repellency rates of 96% against stable flies, Stomoxys calcitrans (L.) and 79% against houseflies, Musca domestica (L.), respectively. This finding suggested that the application of repellent could be used as part of filth fly management. Further evaluations of catnip oil toxicity were conducted to provide a broad‐spectrum safety profile of catnip oil use as a potential biting and nuisance insect repellent in urban settings. Acute oral, dermal, inhalation, primary dermal and eye irritation toxicity tests were performed. The acute oral LD₅₀ of catnip oil was found to be 3160 mg/kg body weight (BW) and 2710 mg/kg BW in female and male rats, respectively. The acute dermal LD₅₀ was > 5000 mg/kg BW. The acute inhalation LD₅₀ was observed to be > 10 000 mg/m³. Primary skin irritation tested on New Zealand white rabbits showed that catnip oil is a moderate irritant. Catnip oil was classified as practically non‐irritating to the eye. In comparison with other U.S. Environmental Protection Agency‐approved mosquito repellents (DEET, picaridin and p‐menthane‐3,8‐diol), catnip oil can be considered as a relatively safe repellent, which may cause minor skin irritation.     

Efficacy of various synthetic pyrethroid-impregnated encasement materials against house dust mite under laboratory conditions

The acaricidal activity of synthetic pyrethroid and benzyl benzoate against Dermatophagoides pteronyssinus was examined in the laboratory, using a specially designed test set up. On the basis of median lethal dose (LD₅₀) values, the compound found to be most toxic to D. pteronyssinus was benzyl benzoate (LD₅₀ = 50 mg/m²), followed by permethrin (LD₅₀ = 76.7 mg/m²), deltamethrin (LD₅₀ = 146.7 mg/m²), esbioallenthrin (LD₅₀ = 186.6 mg/m²) and lamdacyhalothrin (LD₅₀ = 756.6 mg/m²). Very low toxicity was observed with bifenthrin (LD₅₀ = 5157.8 mg/m²). A laboratory control trial was also carried out to compare the acaricidal activity (residual effect) of four pyrethroids impregnated on woven and non-woven encasement materials against house dust mites during a 4-month period. Of the pyrethroids used in this study, esbioallenthrin demonstrated the highest acaricidal activity, and of the pyrethroid impregnated materials, the non-woven encasement material was more effective than the woven encasement material.     

Protective role of <Emphasis Type="SmallCaps">l</Emphasis>-ascorbic acid on antioxidant defense system in erythrocytes of albino rats exposed to nickel sulfate

In this experimental study, we investigated whether l-ascorbic acid has any influence on the blood antioxidant defense system, lipid peroxidation and hematological parameters of the albino rats exposed to nickel sulfate(NiSO₄).Twenty four adult rats were divided into four groups of six animals in each group. The control rats were untreated and comprised Group I. Group II rats were administered nickel sulfate (2.0 mg/100 g b.wt.; intraperitonially, i.p.). Group II rats were treated orally l-ascorbic acid (50 mg/100 g b.wt.) and Group IV rats were given both nickel sulfate and l-ascorbic acid simultaneously on alternate days until the tenth dose. The hematological parameters were assessed: red blood corpuscle counts, packed cell volume %, hemoglobin concentration, white blood corpuscle counts and platelets count decreased significantly and clotting time increased significantly in nickel treated rats. We also observed increase malondialdehyde (MDA) and decrease glutathione level (GSH) in erythrocytes of nickel treated rats. The activities of erythrocyte antioxidant enzymes like superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT) were significantly increased in rats treated with nickel sulfate. Simultaneously treatment of l-ascorbic acid exhibited a possible protective role on the toxic effect of nickel sulfate on the hematological values, erythrocyte MDA and GSH concentrations as well as antioxidant enzymatic defense system.     

Isolation and identification of<Emphasis Type="Italic">Streptomyces</Emphasis> sp. and assay of its exocellular water-soluble blue pigments

A bacterial strain producing a great amount of blue pigment during submerse fermentation was isolated and identified. Based on morphological characteristics cell-wall chemotype and sequence of 16S rRNA gene, the strain should belong to the genusStreptomyces; it had 99.4% homology of 16S rRNA gene sequence with that ofStreptomyces indigocolor. The pigment production by the strain was affected by carbon and nitrogen sources. The main components of the pigment mixture (detected by HPLC and TLC) were tentatively classified as actinorhodin-related compounds. The pigment was relatively stable against light and higher temperature but was sensitive to low pH. The preliminary acute-toxicity determination showed that the pigment was nontoxic (LD₅₀>15 mg/g).     

Design of liposomes to improve delivery of amphotericin-B in the treatment of aspergillosis

The efficacy and toxicity of free and liposome intercalated amphotericin-B (Amp-B) in controlling Aspergillosis, caused byAspergillus fumigatus in BALB/c mice were studied. Liposomal Amp-B had higher LD₅₀ (8.1 mg/kg) as compared to that of the free drug (1.2 mg/kg). An improvement in the therapeutic index of the drug was observed with liposomal formulation of the drug. We also focussed on the effect of lipid composition and surface sugar in modulating the therapeutic potency of Amp-B. The most effective liposomal preparation was composed of egg phosphatidylcholine (EPC) : L--phosphatidylethanolamine, dipalmitoyl (DPPE): cholesterol (Chol) in the molar ratio of 6:1:3. Amp-B intercalated into mannose grafted liposomes (LD₅₀ = 9.3 mg/kg) was more effective as compared to the other formulation tested.     

Long-term exposure to chromium(VI) oxide leads to defects in sulfate transport system in chinese hamster ovary cells

Chromium(VI) resistant Chinese hamster ovary (CHO) cell lines were established in this study by exposing parental CHO-K1 cells to sequential increases in CrO₃ concentration. The final concentration of CrO₃ used for selection was 7 μM for Cr7 and 16 μM for Cr16 cells. Cr16-1 was a subclone derived from Cr16 cells. Next, these resistant cells were cultured in media without CrO₃ for more than 6 months. The resistance of these cells to CrO₃ was determined by colony-forming ability following a 24-h treatment. The LD₅₀ of CrO₃ for chromium(VI) resistant cells was at least 25-fold higher than that of the parental cells. The cellular growth rate, chromosome number, and the hprt mutation frequency of these chromium(VI) resistant cells were quite similar to their parental cells. The glutathione level, glutathione S-transferase, catalase activity, and metallothionine mRNA level in Cr7 and Cr16-1 cells were not significantly different from their parental cells. Furthermore, Cr16-1 cells were as sensitive as CHO-K1 cells to free-radical generating agents, including hydrogen peroxide, nickel chloride, and methanesulfonate methyl ester, and emetine, i.e., a protein synthesis inhibitor. The uptake of chromium(VI) and the remaining amount of this metal in these resistant and the parental cell lines were assayed by atomic absorption spectrophotometry. Experimental results indicated that a vastly smaller amount of CrO₃ entered the resistant cell lines than their parental cells did. A comparison was made of the sulfate uptake abilities of CHO-K1 and chromium(VI) resistant cell lines. These results revealed that the uptake of sulfate anion was substantially reduced in Cr7 and Cr16-1 cells. Extracellular chloride reduced sulfate uptake in CHO-K1 but not in Cr16-1 cells. Therefore, the major causative for chromium(VI) resistance in these resistant cells could possibly be due to the defects in SO₄^2-/C1^? transport system for uptake chromium(VI).     

Histopathological and biological studies of the effect of cadmium on Rhinella arenarum gonads

This study was to determine the lethal dose 50 (LD₅₀) of CdCl₂ in adult Rhinella arenarum and analyzed the effect of two sublethal doses (0.5 and 5 mg/kg) of the xenobiotic in gonads. The 48 h LD₅₀ were 50.0 and 49.8 mg/kg for males and females respectively. Alterations in the ovary were evidenced by nuclear pleomorphism and cytoplasmic vacuolization of the oocytes at the early stages of development with the highest dose and an increase in the population of atretic oocytes. In the interstitial tissue we noticed congestion, edema and fibroblast proliferation. The nuclear maturation of the oocytes was affected by the xenobiotic in a dose- and time-dependent manner. In males, treatment with 5 mg/kg of cadmium (Cd) caused a decrease in the concentration, viability and straight progressive motility of sperm while there was an increase in immotile sperm. Testis histopathology revealed dilated seminiferous tubules, disappearance of cysts, tissue disorganization and leukocyte infiltration. Numerous germ cells showed hydropic tumefaction or signs of focal necrosis. The Cd content in animals intoxicated gonads with the highest sublethal dose was significantly higher than in the control. Results indicate that R. arenarum gonads are target for the xenobiotic, compromising the formation of gametes competent for fertilization, the effective CdCl₂ dose being 5 mg/kg.     

Stabilized ferrous gluconate as iron source for food fortification

The iron bioavailability and acute oral toxicity in rats of a ferrous gluconate compound stabilized with glycine (SFG), designed for food fortification, was studied in this work by means of the prophylactic method and the Wilcoxon method, respectively. For the former studies, SFG was homogenously added to a basal diet of low iron content, reaching a final iron concentration of 20.1±2.4 mg Fe/kg diet. A reference standard diet using ferrous sulfate as an iron-fortifying source (19.0±2.1 mg Fe/kg diet) and a control diet without iron additions (9.3±1.4 mg Fe/kg diet) were prepared in the laboratory in a similar way. These diets were administered to three different groups of weaning rats during 23 d as the only type of solid nourishment. The iron bioavailability of SFG was calculated as the relationship between the mass of iron incorporated into hemoglobin during the treatment and the total iron intake per animal. This parameter resulted in 36.6±6.2% SFG, whereas a value of 35.4±8.0% was obtained for ferrous sulfate. The acute toxicological studies were performed in two groups of 70 female and 70 male Sprague-Dawley rats that were administered increasing doses of iron from SFG. The LD₅₀ values of 1775 and 1831 mg SFG/kg body wt were obtained for female and male rats, respectively, evidencing that SFG can be considered as a safe compound from a toxicological point of view.     

Studies on the embryotoxicity and mutagenicity of mycotoxins

Embryotoxicity: Aflatoxin B₁(AFB₁), G₁ (AFG₁), and Patulin (PA) were investigated in NMRI mice for embryotoxic and teratogenic activity. These three mycotoxins were injected intraperitoneally or given orally on day 12 and 13 of pregnancy. AFB₁ (15, 45, and 90 mg/kg ip or 45 mg/kg po) produced a moderate retardation in the fetal development and a dose related increase of cleft palates, wavy ribs, and diaphragm changes. The effects after injection of AFG₁ (45 and 90 mg/kg ip) were reduction of fetal weights, increase of diaphragm changes, and malformations of kidneys. PA (1.25, 2.5, and 3.75 mg/kg ip or 3.75 mg/kg po) elevated the rate of cleft palates after 3.75mg/kg. In the dominant lethal assay neither PA (2.5 and 5 mg/kg ip) nor AFB₁) (15 and 45 mg/kg ip) increased the frequency of the dominant lethal mutations. Both mycotoxins showed no mutagenic activity in this test system. The capability of AFB₁, AFG₁, and PA to induce chromosome damages in vivo was tested in the Chinese Hamster by examination of bone marrow cells, each after two oral doses (AFB₁: 12.5 and 25 mg/kg; 25 and 50 mg/kg; PA: 10 and 20 mg/kg). The three mycotoxins induced chromosome aberrations in the following order of activity: PA > AFB₁ > AFG₁.     

In vivo antiplasmodial activity of 11(13)-dehydroivaxillin from Carpesium ceruum

The whole plants of Carpesium genus are used in traditional medicine as anti-pyretic, analgesic and vermifugic, including a topical application for sores and inflammation. A previous study on Carpesium genus suggested that the antiplasmodial activity against Plasmodium falciparum was due to the existence of 11(13)- dehydroivaxillin (DDV) from EtOAc extracts of C. ceruum (Compositae). Here, the antimalarial activity of DDV was evaluated against Plasmodium berghei in mice. The LD₅₀ of the compound was determined as 51.2 mg/kg, while doses of 124 mg/kg and above were found to be lethal to mice. DDV (2, 5, 10 mg/kg/day) exhibited a significant blood schizontocidal activity in 4-day early infection, repository evaluation and in an established infection with a significant mean survival time comparable to that of the standard drug, chloroquine, 5 mg/kg/day. DDV possesses a promising antiplasmodial activity, which can be exploited in malaria therapy.     

Insecticidal and feeding deterrent activities of essential oils in the cabbage looper,Trichoplusia ni (Lepidoptera: Noctuidae)

Ten essential oils were tested against the cabbage looper, Trichoplusia ni larvae for contact, residual and fumigant toxicities and feeding deterrent effects. Against third instar T. ni, Syzygium aromaticum (LD₅₀ = 47.8 μg/larva), Thymus vulgaris (LD₅₀ = 52.0 μg/larva) (the two positive controls) and Cinnamomum glanduliferum (LD₅₀ = 76.0 μg/larva) were the most toxic via topical application. Litsea pungens (LD₅₀ = 87.1 μg/larva), Ilex purpurea (LD₅₀ = 94.0 μg/larva), Cinnamomum cassia (LD₅₀ = 101.5 μg/larva) and Litsea cubeba (LD₅₀ = 112.4 μg/larva) oils were equitoxic. Thymus vulgaris (LC₅₀ = 4.8 mg/ml) and S. aromaticum (LC₅₀ = 6.0 mg/ml) oils were the most toxic in residual bioassays. Cymbopogon citratus (LC₅₀ = 7.7 mg/ml) and C. cassia (LC₅₀ = 8.5 mg/ml) oils were equitoxic followed by Cymbopogon nardus (LC₅₀ = 10.1 mg/ml) in this bioassay. The remaining five oils showed little or no residual effects. In a fumigation bioassay, L. cubeba (LC₅₀ = 16.5 μl/l) and I. purpurea (LC₅₀ = 22.2 μl/l) oils were the most toxic. Cinnamomum glanduliferum (LC₅₀ = 29.7 μl/l) and Sabina vulgaris (LC₅₀ = 31.2 μl/l) oils were equitoxic. Interestingly, S. aromaticum did not exhibit any fumigant toxicity. Cymbopogon citratus, C. nardus and C. cassia strongly deterred feeding by third instar T. ni (DC₅₀s = 26.9, 33.8 and 39.6 μg/cm², respectively) in a leaf disc choice bioassay. The different responses of T. ni larvae to the oils in different bioassays suggest that these essential oils exhibit different modes of action. Based on their comparable efficacy with essential oils already used as active ingredients in many commercial insecticides (i.e. clove oil and thyme oil), some of these essential oils may have potential as botanical insecticides against T. ni.     

A toxic substance produced by Nocardia otitidiscaviarum isolated from cutaneous nocardiosis

During our studies on toxic substances from clinically isolated Nocarida, a new isolate identified as Nocardia otitidiscaviarum from cutaneous nocardiosis was found to produce a toxic substance called HS-6 that had strong in vitro as well as in vivo toxicity. The mouse intraperitoneal LD₅₀ value was 1.25 mg/kg and the ED₅₀ value for L1210 cultured cells was 0.3 ng/ml. The structure of HS-6 was determined and found to belong to the 16-membered macrocyclic group with a molecular formula of C₄₃H₆₈O₁₂. HS-6 also showed activity against pathogenic fungi such as Cryptococcus neoformans.     

Simple Isolation of Antimycin A1 and Some of Its Toxicological Properties

An unidentified actinomycete, RTI 246, was found to produce antimycin A₁ in high yield on a high protein cereal medium. The antibiotic compound was extracted from the cells and isolated in pure form by crystallization. It was identified by ultraviolet, infrared, nuclear magnetic resonance, and mass spectroscopy and by alkaline hydrolysis to antimycic acid and a neutral lactone. The intravenous LD₅₀ was 1.0 mg/kg in white mice, whereas the intraperitoneal LD₅₀ was 1.50 ± 0.19 mg/kg. Animals receiving an intraperitoneal injection displayed an incoordination of the hind limbs and impaired reflexes before showing signs of respiratory distress. These findings indicated that antimycin A₁ possesses a neurotoxic property separate from its well-documented property as a respiratory poison.