Signaling pathways involved in the antiproliferative effect of molecular iodine in normal and tumoral breast cells: evidence that 6-iodolactone mediates apoptotic effects

Previous reports have documented the antiproliferative properties of I(2) and the arachidonic acid (AA) derivative 6-iodolactone (6-IL) in both thyroid and mammary glands. In this study, we characterized the cellular pathways activated by these molecules and their effects on cell cycle arrest and apoptosis in normal (MCF-12F) and cancerous (MCF-7) breast cells. Low-to-moderate concentrations of I(2) (10-20 microM) cause G1 and G2/M phase arrest in MCF-12F and caspase-dependent apoptosis in MCF-7 cells. In normal cells, only high doses of I(2) (40 microM) induced apoptosis, and this effect was mediated by poly (ADP-ribose) polymerase-1 (PARP1) and the apoptosis-induced factor, suggesting an oxidative influence of iodine at high concentrations. Our data indicate that both I(2) and 6-IL trigger the same intracellular pathways and suggest that the antineoplasic effect of I(2) in mammary cancer involves the intracellular formation of 6-IL. Mammary cancer cells are known to contain high concentrations of AA, which might explain why I(2) exerts apoptotic effects at lower concentrations only in tumoral cells.

Development of an edible rabies vaccine in maize using the Vnukovo strain

The objective of this study was to obtain transgenic maize expressing the rabies virus glycoprotein (G) of the Vnukovo strain and to evaluate its immunogenicity in mice, by the oral route. The ubiquitin maize promoter fused to the whole coding region of the rabies virus G gene, and a constitutive promoter from cauliflowermosaic virus (CaMV)were used. Maize embryogenic callus were transformed with the above construct by biolistics. Regenerated maize plants were recovered and grown in a greenhouse. The presence of the G gene and its product was detected by PCR and western blot, respectively. The amount of G protein detected in the grains was approximately 1% of the total soluble plant protein. Transformed kernels containing 50 microg of G protein were given once by the oral route in adult mice (BALB-C strain). Challenge was undertaken at 90-days post-vaccination using a lethal dose of a vampire bat rabies virus (100 LD 50% in mice); vampire bats are one of the main reservoirs in Latin America. The edible vaccine induced viral neutralizing antibodies (VNA) which, protected mice 100% against challenge. The control group did not survive. The G protein of the Vnukovo strain expressed in transgenic maize may be considered as an oral immunogen against rabies, conferring cross-protection.

Effects of a mixture of fatty acids from sugar cane (Saccharum officinarum L.) wax oil in two models of inflammation: zymosan-induced arthritis and mice tail test of psoriasis

A mixture of fatty acids obtained from sugar cane (Saccharum officinarum L.) wax oil (FAM), in which the main constituents are palmitic, oleic, linoleic, and linolenic acids, was evaluated in two models of inflammation: zymosan-induced arthritis and in the tail test for psoriasis, both on mice. In the first model, FAM significantly reduced zymozan-induced increase of beta glucuronidase (DE(50) 90+/-7 mg/kg). Histopathological studies showed inhibition in cellular infiltration and reduction of synovial hyperplasia and synovitis, whereas in the second test, histopathological and ultrastructural studies showed that topical application of FAM induced orthokeratosis with the presence of keratohyalin granules in the previously parakeratotic adult mouse tail, and without effects on epidermal thickness. The ED(50) of FAM in this model was 155+/-10 mg. The results of our studies showed that topical application of FAM exerts an important anti-inflammatory activity in both tests without evidence of irritant effects. The anti-inflamatory effects exerted by FAM may be due to its inhibitory effects on arachidonic acid metabolism. To our knowledge, this is the first report on the anti-inflammatory effect of sugar cane by-products in experimental models of arthritis and psoriasis.

DNA damage in outdoor workers occupationally exposed to environmental air pollutants

BACKGROUND

Health concerns about the exposure to genotoxic and carcinogenic agents in the air are particularly significant for outdoor workers in less developed countries.

AIMS

To investigate the association between personal exposure to a group of air pollutants and severity of DNA damage in outdoor workers from two Mexican cities.

METHODS

DNA damage (Comet assay) and personal exposure to volatile organic compounds, PM(2.5), and ozone were investigated in 55 outdoor and indoor workers from México City and Puebla.

RESULTS

In México City, outdoor workers had greater DNA damage, reflected by a longer tail length, than indoor workers (median 46.8 v 30.1 mum), and a greater percentage of highly damaged cells (cells with tail length > or =41 microm); in Puebla, outdoor and indoor workers had similar DNA damage. There were more alkali labile sites in outdoor than indoor workers. The DNA damage magnitude was positively correlated with PM(2.5) and ozone exposure. Outdoor and indoor workers with > or =60% of highly damaged cells (highly damaged workers) had significantly higher exposures to PM(2.5), ozone, and some volatile organic compounds. The main factors associated with the highly damaged workers were ozone, PM(2.5), and 1-ethyl-2-methyl benzene exposure.

CONCLUSIONS

With this approach, the effects of some air pollutants could be correlated with biological endpoints from the Comet assay. It is suggested that the use of personal exposure assessment and biological endpoints evaluation could be an important tool to generate a more precise assessment of the associated potential health risks.

NF-κB signaling blockade by Bay 11-7085 during early cardiac morphogenesis induces alterations of the outflow tract in chicken heart

Nuclear factor kappaB (NF-kappaB) is a pleiotropic transcription factor implicated in the regulation of diverse morphologic cardiac alterations, for which the p50 and p65 subunits form the most prevalent dimeric form in the heart. NF-kappaB is inactivated by proteins of the IkappaB family, which trap it in the cytoplasm. It is not known whether NF-kappaB influences cardiac development.

OBJECTIVE

Here we investigated the role of NF-kappaB in regulating transcription in chicken heart morphogenesis. Specifically, we tested whether NF-kappaB activation is required for normal formation of the outflow tract (OFT) during a critical stage of heart development.

METHODS AND RESULTS

We designed a reporter vector with kappaB binding sites for Rel family members in the promoter, upstream from the cDNA of Green Fluorescent Protein (GFP). This construct was injected directly into the developing heart of chicken embryos. NF-kappaB activation was subsequently inhibited by administration of the specific pharmacological agent Bay 11-7085. We found that forced NF-kappaB expression was associated with multiple congenital cardiac alterations of the OFT (mainly IVC, DORV and great arteries stenosis).

CONCLUSION

These findings indicate that blockade of NF-kappaB induces apoptosis and is an important factor in the development of OFT during cardiogenesis. However, it remains unknown which members of the Rel family are relevant in this process.

Pan-African polyspecific antivenom produced by caprylic acid purification of horse IgG: an alternative to the antivenom crisis in Africa

A polyspecific Pan-African antivenom has been produced from the plasma of horses immunized with a mixture of the venoms of Echis ocellatus, Bitis arietans and Naja nigricollis, the three most medically important snakes in sub-Saharan Africa. The antivenom is a whole IgG preparation, obtained by caprylic acid precipitation of non-IgG plasma proteins. The antivenom effectively neutralizes the most important toxic activities of the three venoms used in the immunization in standard assays involving preincubation of venom and antivenom before testing. This antivenom compares favourably with other antivenoms designed for use in Africa with respect to neutralization of the toxins present in the venom of E. ocellatus. Caprylic acid fractionation of horse hyperimmune plasma is a simple, convenient and cheap protocol for the manufacture of high quality whole IgG antivenoms. It constitutes a potentially valuable technology for the alleviation of the critical shortage of antivenom in Africa.

Further studies on a mixture of fatty acids from sugar cane (Saccharum officinarum) wax oil in animal models of hypersensitivity

A mixture of fatty acids obtained from sugar cane wax oil, the main components of which are palmitic, oleic, linoleic and linolenic acids, was evaluated topically in two experimental models of hypersensitivity: the ear swelling response to ovalbumin in sensitized mice (ED50 edema: 0.63 +/- 0.06 mg/ear, ED50 myeloperoxidase: 0.56 +/- 0.04 mg/ear, ED50 degranulated cells: 0.70 +/- 0,08 mg/ear) and oxazolone-induced contact hypersensitivity in mice (ED50 edema: 1.63 +/- 0.26 mg/ear, ED50 myeloperoxidase: 1.50 +/- 0.28 mg/ear, ED50 degranulated cells: 1.69 +/- 0.08 mg/ear). Also, the effect of this mixture was studied on the chemotaxis induced by fmlp (ED50: 25 +/- 3 microg/mL). The mixture showed anti-inflammatory activity in both in vivo models of allergy and in the chemotaxis test. Therefore, these results provide evidence about the potential usefulness of the mixture of fatty acids from sugar cane wax oil in cutaneous inflammatory and allergic disorders.

Diversity and species composition of sand flies (Diptera: Psychodidae) in a Venezuelan urban focus of cutaneous leishmaniasis

The present study examined the spatial and temporal abundance and diversity of phlebotomine sand flies in an area of Venezuela that is an ancient focus of leishmaniasis. The study was conducted in 6 stations in urban localities in Trujillo City, located in northwestern Venezuela (9 degrees 22' 24" N, 70 degrees 26' 08" W), which is located in a mountain range in the Andean ecoregion (altitude = 600-1,010 m). During 1995-99, entomological surveys were conducted after and before the rainy season. Shannon light traps were operated from 1800 to 2000 h in peridomestic site trap locations. Twelve species were captured, and Lutzomyia youngi, L. ovallesi, L. scorzai, L. gomezi, L. lichyi, and L. shannoni occurred at all localities in each year. The abundance of these species showed low variation over time but high variation between localities. The Sørensen similarity index, used to compare diversity between years within each locality, ranged from 0.60 at Carmona to 0.84 at La Hacienda. Sand fly communities exhibited annual variation in species richness and diversity. Variations were affected more by changes in species abundance than by changes in species composition. Lutzomyia ovallesi, L. lichyi, and L. scorzai had the highest coefficient of variation between years (63, 38, and 23%, respectively).

Genotoxic differences by sex in nasal epithelium and blood leukocytes in subjects residing in a highly polluted area

We describe differences by sex in genotoxic damage found in a population of medical students exposed to a highly oxidative atmosphere, compared with a control group, measured by the single-cell gel electrophoresis assay and histological changes in nasal epithelium smears. Cells were obtained from the nasal epithelium and blood leukocytes. Higher DNA damage in nasal cells and leukocytes was found in males compared to females and control subjects. The percentage of squamous metaplastic changes in the nasal epithelium was also higher in males compared with females and controls. The co-mutation of normal nasal epithelium by squamous cells might modify its protective function in the nose, increasing the risk of damage to the lower respiratory tract. Although, as medical students, males and females were exposed to the same environment and activity patterns, male genotoxicity damage was higher in control and exposed subjects. More research should be done in order to identify direct or indirect sexual hormone intervention.

Anti-inflammatory and analgesic effects of a mixture of fatty acids isolated and purified from sugar cane wax oil

The anti-inflammatory and analgesic effects of FAM, a defined mixture of fatty acids isolated from sugar cane (Saccharum officinarum L.), was evaluated. Oral administration of this mixture showed anti-inflammatory activity in the cotton pellet granuloma assay and in the carrageenin-induced pleurisy test, both in rats, as well as in the peritoneal capillary permeability test in mice. In addition, FAM showed analgesic properties in the hot-plate model and in the acetic acid-induced writhings test, both in mice. In conclusion, these results provide evidence on the potential usefulness of the mixture of fatty acids from sugar cane wax oil in inflammatory disorders.

Analysis of genetic heterogeneity of hepatitis C viruses in Central America reveals a novel genetic lineage. Brief report

Hepatitis C virus (HCV) has high genomic variability and at least six different types have been reported. The genotypes distribution is currently unknown among HCV strains circulating in Central America. In order to study the degree of genetic variability of strains isolated in Costa Rica, sequence data obtained from the 5' non coding region from 7 patients from Costa Rica were compared with published sequences from 57 strains of all types. The phylogenetic analysis revealed the existence of type 1 strains of a novel genetic lineage, recently described for some South American countries, and indicates an increasing diversification of HCV.

Role of P53 functionality in the genotoxicity of metronidazole and its hydroxy metabolite

P53 mediates several biological processes for preservation of genetic stability such as the induction of cell cycle arrest, DNA repair or apoptosis in response to DNA damage. The antiparasitic drug, 1-(2-hydroxyethyl)-2-methyl-5-nitroimidazole (metronidazole, MTZ) is able to increase lymphocyte proliferation inducing at the same time chromosomal aberrations. Trying to understand this unexpected event we used cell lines with different P53 functionality, determining the proliferation capacity and the induction of micronuclei (MN) after the treatment with MTZ or its hydroxy metabolite. Our results show that MTZ increased proliferation in a dose response manner in all P53 functional cell lines without inducing changes on the levels of P53 nor MN. However, MTZ hydroxy metabolite induced a dose response increase of P53 and MN, while cell proliferation was not increased. Several studies have shown that the hydroxy metabolite is more potent than MTZ itself. Only in cell lines that do not have a functional P53, MTZ and its metabolite increased both cell proliferation and MN. MTZ use is increasing and its carcinogenicity has not been discarded. Our data indicate that MTZ hydroxy metabolite is potentially a carcinogen and needs to be further studied.

Cytotoxic and genotoxic effects of As, MMA, and DMA on leukocytes and stimulated human lymphocytes

Inorganic arsenic is a human carcinogen associated with different types of cancer. Arsenic metabolism produces two methylated species: monomethylarsonic and dimethylarsinic acids. Although this metabolic route has been involved in arsenic detoxification, it is still not clear whether these methylated metabolites participate in the carcinogenic process. In this work, we studied the cytotoxic and genotoxic effects of arsenic and its metabolites. Cytotoxicity was evaluated in cultured lymphocytes from three donors. Mitotic and replication indices were the parameters analyzed. The results indicate a clear cytotoxic effect by sodium arsenite but not by its metabolites. Genotoxicity was assessed by the single cell gel electrophoresis assay. Sodium arsenite increased DNA migration in stimulated lymphocytes only at doses greater than 5 x 10(-6) M; meanwhile in leukocytes a weak response was observed. Monomethylarsonic acid produced in leukocytes a weak induction of DNA damage, while in stimulated lymphocytes, a dose-increase in DNA migration was observed. The injury caused by dimethylarsinic acid was more evident than that observed in cultures treated with sodium arsenite and monomethylarsonic acid in stimulated lymphocytes, although in leukocytes no effect on DNA migration was found. In conclusion, only sodium arsenite had the capacity to alter mitotic and replication indices, while sodium arsenite and its metabolites were capable of inducing single strand DNA breaks on stimulated human lymphocytes treated in vitro for 24 h; however, the differences observed were between individual responses, one donor being more susceptible even at the lower doses. This individual susceptibility to arsenic compounds has been repeatedly observed for different end-points and should be studied further.

DNA breakage due to metronidazole treatment

The mutagenicity of metronidazole [1-(hidroxyethyl)-2-methyl-5-nitroimidazole] (MTZ) has been shown in different prokaryotic systems. However, data on human cells are still contradictory. In this study DNA damage was determined by the single cell gel electrophoresis (SCGE) assay, in lymphocytes from 10 healthy subjects treated with therapeutic doses of this drug. Samples were obtained before treatment, as well as 1 and 15 days after ending treatment. Results showed a significant increase of DNA strand breaks 1 day after ending treatment, although, an inverse correlation between the amount of DNA damage and plasma concentrations of MTZ was obtained. Thus, the observed damage may be induced by some MTZ metabolite rather than by the parent drug. Interestingly, the amount of DNA damage returned to basal levels 15 days after ending treatment, except in two individuals. This persistent damage should be further investigated.

Comparison between IgG and F(ab')(2) polyvalent antivenoms: neutralization of systemic effects induced by Bothrops asper venom in mice, extravasation to muscle tissue, and potential for induction of adverse reactions

Whole IgG and F(ab')(2) equine-derived polyvalent (Crotalinae) antivenoms, prepared from the same batch of hyperimmune plasma, were compared in terms of neutralization of the lethal and defibrinating activities induced by Bothrops asper venom, their ability to reach the muscle tissue compartment in envenomated mice, and their potential for the induction of adverse reactions. Both preparations were adjusted to the same potency against the lethal effect of B. asper venom in experiments involving preincubation of venom and antivenom. Then, "rescue" experiments were performed, i.e. antivenom was administered either intravenously or intramuscularly at various times after envenomation. IgG and F(ab')(2) antivenoms were equally effective in the neutralization of lethality, both being more effective when administered i.v. than after i.m. injection. Neutralization decreased as the time lapse between envenomation and treatment increased. No significant differences were observed in the ability of antivenoms to neutralize defibrinating activity of B. asper venom in experiments involving independent injection of venom and antivenoms. There was a much higher accumulation of equine antibodies in muscle tissue that had been injected with B. asper venom than in non-envenomated tissue, indicating that venom-induced microvessel damage probably favors a prominent and similar extravasation of both IgG and F(ab')(2) antibodies. This may explain the similar effectiveness of both types of antivenom in previously reported studies on the neutralization of venom-induced local tissue damage. Both IgG and F(ab')(2) antivenoms activate human complement in vitro and induce an anti-equine immunoglobulin response in mice, indicating that Fc removal per se does not eliminate the potential for inducing adverse reactions. However, IgG antivenom had higher anticomplementary activity and induced a stronger anti-immunoglobulin response than F(ab')(2) antivenom.

Venom of the crotaline snake Atropoides nummifer (jumping viper) from Guatemala and Honduras: comparative toxicological characterization, isolation of a myotoxic phospholipase A(2) homologue and neutralization by two antivenoms

A comparative study was performed on the venoms of the crotaline snake Atropoides nummifer from Guatemala and Honduras. SDS-polyacrylamide gel electrophoresis, under reducing conditions, revealed a highly similar pattern of these venoms, and between them and the venom of the same species from Costa Rica. Similar patterns were also observed in ion-exchange chromatography on CM-Shephadex C-25, in which a highly basic myotoxic fraction was present. This fraction was devoid of phospholipase A(2) activity and strongly reacted, by enzyme-immunoassay, with an antiserum against Bothrops asper myotoxin II, a Lys-49 phospholipase A(2) homologue. A basic myotoxin of 16 kDa was isolated to homogeneity from the venom of A. nummifer from Honduras, showing amino acid composition and N-terminal sequence similar to those of Lys-49 phospholipase A(2) variants previously isolated from other crotaline snake venoms. Guatemalan and Honduran A. nummifer venoms have a qualitatively similar toxicological profile, characterized by: lethal; hemorrhagic; myotoxic; edema-forming; coagulant; and defibrinating activities, although there were significant quantitative variations in some of these activities between the two venoms. Neutralization of toxic activities by two commercially-available antivenoms in the region was studied. Polyvalent antivenom produced by Instituto Clodomiro Picado was effective in the neutralization of: lethal; hemorrhagic; myotoxic; coagulant; defibrinating; and phospholipase A(2) activities, but ineffective against edema-forming activity. On the other hand, MYN polyvalent antivenom neutralized: hemorrhagic; myotoxic; coagulant; defibrinating; and phospholipase A(2) activities, albeit with a lower potency than Instituto Clodomiro Picado antivenom. MYN antivenom failed to neutralize lethal and edema-forming activities of A. nummifer venoms.

Is the capacity of lead acetate and cadmium chloride to induce genotoxic damage due to direct DNA-metal interaction?

Even though the toxic effects of lead and cadmium compounds have been studied over many years, inconsistent results have been obtained about their mutagenic, clastogenic and carcinogenic properties. However, these metals are considered to be potential human carcinogens. The mechanism of metal-induced carcinogenesis is still unknown, but one possible pathway may involve the interaction of metals with DNA, either directly or indirectly. In this work we explore the capacity of lead, cadmium or a mixture of both metals to interact with acellular DNA, by employing a variant of the comet assay. Our results, using low non-cytotoxic metal concentrations (0.01, 0.1 and 1.0 microM) with the standard protocol for the acellular assay, showed an induction of DNA damage in cells of all organs studied; however, basal DNA damage was different in each organ. To confirm that we were working with pure DNA, proteinase K was added to the lysis solution. With this enriched-lysis solution we found a negative response in the induction of DNA damage in cells derived from the liver, kidney and lung of CD-1 male mice. To support the results obtained by the enriched-acellular assay, we studied the capacity of lead and cadmium (0.1 microM) to induce breaks in pooled genomic DNA in cells of the same organs, with negative results. Consistent with these findings, these metals do not induce DNA breaks in the plasmid pUSE amp+. On the whole, we did not detect direct induction of DNA strand breaks by lead acetate, cadmium chloride or a mixture of both metals, all at low non-cytotoxic concentrations. However, we found an induction of lipid peroxidation and an increase in free radical levels in the different organs of CD-1 male mice after inhalation of lead acetate (0.0068 microg/cc) or cadmium chloride (0.08 microg/cc) for 1 h, suggesting the induction of genotoxicity and carcinogenicity by indirect interactions, such as oxidative stress.

Hevein, an allergenic lectin from rubber latex, activates human neutrophils' oxidative burst

Hevein is an N-acetyl-D-glucosamine (GlcNAc) specific lectin that has been hypothesized to participate in the IgE-mediated allergic reactions in patients with latex allergy. In this work we assessed the specificity and biological effect of hevein purified from rubber latex on human leukocytes, using epifluorescence microscopy and flow cytometry. Purified human granulocytes were stimulated in vitro with hevein, and production of oxidative radicals was measured by reduction of nitroblue tetrazolium formazan. Histochemical staining and flow cytometry showed that hevein recognizes specifically monocytes (CD14+) and neutrophils (CD16+), but not lymphoid cells. Hevein induced oxidative response in purified granulocytes; this effect was 1.3-1.5-fold higher than the effect observed with the lectin WGA (wheat germ agglutinin), or other lectins with different sugar specificity. The induced reactions and cellular recognition by hevein were inhibited with GlcNAc and its oligomers; as well as by glycoproteins containing tri-and tetra-antennary N-glycosydically linked glycans. Our findings suggest that neutrophils are the main target for latex hevein; this lectin induces production of oxidative radicals, which seem to play an important role in tissue damage during latex allergy.