Vasectomy within the public health services in Campinas, São Paulo, Brazil.

OBJECTIVE: To describe some of the characteristics of men who underwent a vasectomy in the public health network of Campinas, São Paulo, Brazil. METHODS: A descriptive study including 202 men randomly selected from a list of all the men vasectomized between 1998 and 2004 in the public health network. RESULTS: Most of the men were 30 years of age or older when vasectomized, had completed elementary school and had two or more children of both sexes. Most of the men came from the lowest income segment of the population: 47.6% in 1998-1999 and 61.3% in 2003-2004. Although the men knew various contraceptive methods, 51.2% reported that their partners were using combined oral contraceptives at the time of surgery. Most men initially sought information on vasectomy at health-care clinics where care was provided by a multidisciplinary team; most received counselling, however, 47.9% of the men waited more than 4 months for the vasectomy. CONCLUSIONS: The profile of the vasectomized men in this study appears to indicate that the low-income population from Campinas, São Paulo, Brazil has access to vasectomy; however, the waiting time for vasectomy reveals that difficulties exist in obtaining this contraceptive method in the public health service.

Antimicrobial activity in methanolic extracts of several plant species from northern Argentina.

Thirty-nine native plant species were collected from the provinces of Chaco and Formosa, in northern Argentina, and were screened for antimicrobial activity. The plants were dried and extracted thoroughly with methanol. The dry extracts, dissolved in dimethylsulfoxide, were tested for inhibition of microbial growth via microplate assay with an oxidation-reduction dye. The test organisms were: Escherichia coli, Salmonella typhimurium, Pseudomonas aeruginosa, Klebsiella pneumoniae, Staphylococcus aureus and Enterococcus faecium. Inhibition of respiratory activities in some of these microbial species was produced by the extracts of Astronium balansae, Geoffroea decorticans, Peltophorum dubium, Geoffroea spinosa, Lantana balansae, Prosopis kuntzei, Prosopis ruscifolia and Bulnesia sarmientoi, with minimal inhibitory concentrations (MIC) ranging from 0.08 to 0.5 mg dry matter/ml. Further in vitro experiments measuring the growth of S. aureus in liquid culture confirmed that all of the above extracts at 2 x MIC were able to inhibit bacterial growth effectively, and that some of them (A. balansae, G. decorticans, P. dubium, G. spinosa, P. kuntzei and B. sarmientoi) were able to reduce the initial number of viable counts by at least one order of magnitude in 10 hours, indicating that these extracts should be investigated further for the possible presence of bactericidal components.

A simple thin-layer chromatographic method for the detection of ergovaline in leaf sheaths of tall fescue (Festuca arundinacea) infected with Neotyphodium coenophialum.

A relatively simple and inexpensive thin-layer chromatographic (TLC) method is described for the detection and semiquantitative measurement of ergovaline in leaf sheaths of tall fescue (Festuca arundinacea). Samples were finely ground and extracted with methanol. The extracts were filtered and the methanol was evaporated. The aqueous residue was extracted with hexane, followed by chloroform at pH 9. The chloroform extract was concentrated and further purified on a preparative silica gel TLC plate, developed with toluene/ethyl acetate/acetonitrile (50:10:40). The ergovaline band was scraped and eluted with methanol. The eluant was concentrated and an aliquot was applied to a silica gel TLC plate. The plate was developed successively with chloroform/acetone/acetic acid (90:10:5) and chloroform/ethanol (9:1). Ergovaline was visualized with p-dimethylaminobenzaldehyde and sulfuric acid. Semiquantitation of ergovaline was achieved by comparison with a known standard of ergotamine, which was shown to have the same Rf as ergovaline in this system. Spike recovery of ergotamine averaged 60%, with a limit of detection of 200 microg/kg of dry tall fescue leaf sheaths. The method was applied to 15 tall fescue samples with varying degrees of fungal infection, and ergovaline was identified in all contaminated samples with endophyte infection above 15%. Thin-layer chromatography may be also applicable for tall fescue seed, where the ergovaline content is usually higher and the amount of interfering pigments is much lower.

Screening of some plants from Northern Argentina for their antimicrobial activity.

AIMS: Screening of antimicrobial activity in 25 plant species from Northern Argentina. METHODS AND RESULTS: Inhibition of microbial growth was measured by a microplate assay with an oxidation-reduction indicator (Alamar Blue). Test organisms were: Escherichia coli, Salmonella typhimurium, Pseudomonas aeruginosa, Klebsiella pneumoniae, Staphylococcus aureus and Enterococcus faecium. Weak inhibitory activities (MIC=0.5 mg dry matter ml(-1)) were found in methanolic extracts of Rivina humilis, Crateva tapia, Funastrum claucum and Schinopsis balansae. Stronger bacteriostatic power was detected in Vassobia breviflora (MIC=0.25 mg ml(-1) against Staphylococcus aureus, and 0.5 mg ml(-1) against Enterococcus faecium). This activity was purified five-fold by extraction with dichloromethane, and it was found equally effective against susceptible or antibiotic-resistant strains of Staph. aureus. In addition, the purified extract was synergistic with gentamicin, and it was bactericidal at 24 h, with a concentration of 0.25 mg ml(-1). CONCLUSION: There is a significant antimicrobial activity in Vassobia breviflora. SIGNIFICANCE AND IMPACT OF THE STUDY: Further studies will be required to disclose the potential importance of these findings.

Suppression of spore germination and aflatoxin biosynthesis in Aspergillus parasiticus during and after exposure to high levels of phosphine.

Agar cultures of toxigenic Aspergillus parasiticus NRRL 2999 were exposed to phosphine (PH3), in levels ranging from 0 to 2000 ppm (vol/vol). It was found that with PH3 concentrations of 400 ppm or higher the growth of the fungus was totally arrested. When PH3 was vented and the agar plates were exposed to open air, 100% of the initial CFU developed into fully grown colonies after PH3 levels below 300 ppm, but at higher PH3 concentrations only 50% of the colonies developed. The same strain of A. parasiticus was inoculated into high moisture corn under conditions highly favorable for aflatoxin production, and it was exposed to a range of PH3 levels. After exposure to 500 ppm PH3, both fungal growth and aflatoxin synthesis resumed shortly after elimination of the toxic gas, but after exposure to PH3 levels of 1000 ppm and higher, the physical appearance of the contaminated corn was remarkably changed, showing reduced mycelial growth and almost complete absence of green pigmentation. In addition, aflatoxin synthesis was totally absent for the remainder of the experiment (20 days). These results strongly suggest that exposure to PH3 levels of 1000 ppm or higher could bring about persistent metabolic changes in surviving Aspergillus organisms.

Effects of multiple doses of T-2 toxin on the erythroid response capacity of mice following an extensive experimental bleeding.

Total nucleated cellularity and total erythroid cell populations were measured in spleen and bone marrow of mice at different times after treatment with 3 daily doses of T-2 toxin (2.0 mg/kg). It was found that the initial depletion of hematopoietic cells produced by the toxin was rapidly reverted in spleen, giving way after 48 hr to a significant hypercellularity which after 10 days was 2.5 times the normal levels, but this effect was not observed in bone marrow, which slowly recovered normal cellularity after 5 days. The cytological analysis revealed that there was a highly significant shift in the ratio of erythroid to non-erythroid cells, since erythroid cell populations increased by about 8-fold in spleen and nearly 2-fold in bone marrow between 10 and 35 days after intoxication. In order to test the integrity of the hematopoietic reserve capacity, a hemorrhagic stress was produced in intoxicated animals at 10-50 days after toxin exposure. It was found that the erythroid response capacity was significantly higher in the intoxicated animals compared to anemic controls. The results suggest that the initial cytotoxic damage produced by T-2 toxin in the hematopoietic system is followed by a significant erythroid hypercellularity, which can confer an increased capacity for response to a hemorrhagic emergency.

Differential effects of T-2 toxin on bone marrow and spleen erythropoiesis in mice.

The 59Fe uptake into bone marrow and spleen was measured as a function of time after a single dose of T-2 toxin in mice (2.0 mg/kg, sc). It was found that, after a potent initial inhibition, there was a striking difference in the apparent repair capacity of both tissues: in spleen activity rapidly recovered (48-72 hr), whereas in bone marrow it remained significantly depressed for much longer (about 21 days). These results might be taken to indicate that T-2 toxin produces some sort of irreversible damage to bone marrow. However, working with T-2 toxin-related splenectomized mice it was found that bone marrow erythropoietic activity was rapidly repaired, indicating that, under the conditions of the present experiments, there is no irreversible injury to the marrow haematopoietic or stromal cells. Further studies will be required using multiple doses or continuous toxin exposure in order to test the potential for long-lasting residual injury to the haematopoietic tissue. The present results show that the uptake of 59Fe into both spleen and bone marrow provides a rapid and sensitive method, suitable for primary evaluation of the extent of the erythropoietic damage produced by trichothecene mycotoxins.

Further studies on the hematopoietic damage produced by a single dose of T-2 toxin in mice.

Previous studies revealed that a single dose of T-2 toxin produces a strong inhibition of the 59Fe incorporation into circulating erythrocytes in mice. In the present work it is shown that equivalent doses of T-2 toxin (0.30 mg/kg and above) can produce a relative depletion of granulocyte-macrophage colony-forming cells (CFU-GM) in the bone marrow of treated mice. In additional experiments, both the 59Fe uptake into erythrocytes and the bone marrow CFU-GM were measured as a function of dose and time after a single administration of T-2 toxin. It was found that the initial inhibitory effects are reverted between 24 h and 72 h and that in some cases there is even a significant increase over the normal values, indicating that there may be a compensatory activation of the hematopoietic system. The results presented here suggest that extremely small doses of T-2 toxin can produce a significant degree of bone marrow cytotoxicity and therefore even low level dietary contamination may be of concern.

Acute effects of T-2 toxin on radioactive iron incorporation into circulating erythrocytes in mice.

The 24-h and 72-h incorporation of 59Fe into circulating erythrocytes in mice were strongly inhibited by a single subcutaneous dose of T-2 toxin given 1 h before the radioisotope. The system is extremely sensitive, since a significant effect was detected with T-2 toxin doses as low as 0.30 mg/kg, which is about one-tenth of the LD50 in the BALB/c strain used for the present study. In the treated animals no initial changes were observed in the blood 59Fe levels or in the rate of radioisotope clearance from plasma, indicating that the toxin does not interfere with iron absorption or transport. It is concluded that the inhibition observed reflects the damage produced by this toxin on reticulocytes and/or erythroblasts, and therefore this method could be of value as a very sensitive means of studying the risk of erythropoietic injury produced by dietary exposure to trichothecene mycotoxins.

Metabolism and activation of 1,1-dimethylhydrazine and methylhydrazine, two products of N-nitrosodimethylamine reductive biotransformation.

N-Nitrosodimethylamine (NDMA) and two of its metabolites, monomethylhydrazine (MMH) and 1,1-dimethylhydrazine (UDMH) were metabolized to carbon dioxide by rat liver slices. Under these conditions, NDMA and MMH, but not UDMH, produced reactive metabolites that bound covalently to nucleic acids. Rat liver microsomes or 9000 X g supernatants were able to transform NDMA, MMH and UDMH to formaldehyde. In the case of MMH and UDMH, enzymatic and non-enzymatic pathways of formaldehyde formation were present in both liver microsomes and 9000 X g supernatants. NDMA, MMH and UDMH led to covalent binding in incubation mixtures containing either microsomes or 9000 X g supernatants. In the case of NDMA, the process was enzymatic and required NADPH in both cellular fractions. In the case of MMH, the process was enzymatic in microsomes, and required NADPH and oxygen when using UDMH or MMH and 9000 X g supernatants; interactions of a non-enzymatic nature leading to covalent binding to proteins were dominant. These results suggest that part of the carbon dioxide produced during NDMA metabolism might derive from UDMH and MMH. Similarly, a significant part of the covalent binding of NDMA metabolites to proteins in incubation mixtures containing microsomes or 9000 X g supernatants might derive from enzymatic and non-enzymatic reactions of UDMH or MMH. Also, a minor part of the covalent binding of NDMA reactive metabolites to nucleic acids might be due to further biotransformation of MMH to reactive metabolites. It may be concluded from the present results that biotransformation of NDMA to UDMH and MMH might not be a detoxication process, as previously thought, but one related to some of the toxic effects of NDMA.

Metabolism and activation of 1,1-dimethylhydrazine and methylhydrazine, two products of nitrosodimethylamine reductive biotransformation, in rats.

Nitrosodimethylamine (DMN) and two of its metabolites, methylhydrazine (MH) and 1,1-dimethylhydrazine (UDMH), were metabolized to CO2 by liver slices obtained from Sprague-Dawley rats. Under the conditions used, DMN and MH produced reactive metabolites that bound covalently to nucleic acids, but UDMH did not. Rat liver microsomes or 9,000 X g supernatants were able to transform DMN, MH, and UDMH to CH2O. In the cases of MH and UDMH, enzymatic and nonenzymatic pathways of CH2O formation were observed in both liver microsomes and 9,000 X g supernatants. DMN, MH, and UDMH led to covalent binding (CB) to proteins in incubation mixtures containing either microsomes or 9,000 X g supernatants. In the case of DMN, the process was enzymatic and required NADPH in both cellular fractions. In the case of MH, the process was enzymatic in microsomes and required NADPH and O2. With UDMH or MH and 9,000 X g supernatants, nonenzymatic interactions resulting in CB to proteins dominated. All these results suggest that part of the CO2 produced during DMN metabolism might be derived from UDMH and MH. Similarly, a significant part of the CB of DMN metabolites to proteins in incubation mixtures containing microsomes or 9,000 X g supernatants might be derived from enzymatic and nonenzymatic reactions of UDMH or MH. Also, a minor part of the CB of DMN-reactive metabolites to nucleic acids might have resulted from MH's further biotransformation to reactive metabolites. Overall, biotransformation of DMN and MH might not be a detoxication process, as previously thought, but one related to some of the DMN toxic effects.

No response of pigeon liver to dimethylnitrosamine acute effects.

No evidence for liver necrosis was observed at 24, 48 or 72 h after injection of dimethylnitrosamine (DMN) (70 mg/kg, i.p.) to pigeons. The assessment of possible liver necrosis was made by determination of isocitric dehydrogenase (ICD), glutamate oxalacetate transaminase (GOT) and glutamate pyruvate transaminase (GPT) in plasma. The ability of pigeon liver slices to metabolize CO2 or to give covalent binding of reactive metabolites to nucleic acids was 24 times smaller than that for rat. Similarly, the pigeon liver microsomes or 9000 X g supernatant have DMN-demethylase activity or ability to activate DMN to reactive metabolites that bind covalently to proteins very close to zero. Results suggest that resistance of pigeon liver to DMN acute effects is related to its lack of ability for DMN metabolic activation.

Chicken resistance to dimethylnitrosamine acute effects on the liver: a comparative study with other species.

Dimethylnitrosamine (DMN)-induced liver damage, as measured by the increase in plasma isocitrate dehydrogenase as well as by histologic assessment of necrosis, was marked after DMN ip administration (70 mg/kg) in males of all noninbred species tested (BALB/c mouse, Sprague-Dawley rat, Syrian golden hamster, general purpose guinea pig) but not in the noninbred White Leghorn chicken. At 1 and 3 hours after DMN injection, liver DMN levels were not lower in the chicken as compared to levels in the other species. Furthermore, in all species except the chicken, significant decreases were found at 3 hours as compared to 1 hour after DMN administration. DMN metabolism to CO2 and to formaldehyde, as well as covalent binding of DMN-reactive metabolites to either proteins or nucleic acid, was measured with the use of liver slices, microsomes, and/or 9,000 X g supernatants. Results indicated that chicken liver had a very low capacity for metabolism and activation (29-3,166 times lower than comparable data in mice or hamsters).

Enhancement of the dimethylnitrosamine acute effects in rat liver by prior treatment with triton WR-1339.

Prior administration of Triton WR-1339 (tyloxapol, an anionic surfactant) to noninbred Sprague-Dawley male rats significantly enhanced the intensity of the necrogenic effect of dimethylnitrosamine (DMN) on the liver. This phenomenon was established by determination of NADP+-linked isocitrate dehydrogenase activity in the plasma and by histologic procedures. This enhancing effect was not due to an increase in the levels of DMN that reached the liver, because the content of DMN in the livers of Triton WR-1339-treated or untreated animals at 1 or 3 hours was not significantly different. Triton WR-1339 administration had no effect on DMN liver metabolism to formaldehyde or CO2; in addition, the covalent binding of DMN metabolites to nucleic acids or proteins was not modified by pretreatment with Triton WR-1339. However, in vitro, high concentrations (1 mg/ml) of Triton WR-1339 decreased the intensity of these parameters. This effect disappeared when the concentration was lowered to 0.4 mg/ml. Results are compatible with the hypothesis that the potentiating effects of Triton WR-1339 on liver damage caused by DMN and other hepatotoxins were due to a modification of the response of liver cells to injury.

Further studies on dimethylnitrosamine metabolism, activation and its ability to cause liver injury.

Effects were studied of aminoacetonitrile (AAN), dibenamine (DB) diethyldithiocarbamate (DDTC) dimethylformamide (DMF), disulfiram (DS), and 2-mercapto-1-methylimidazole (MMI) on the in vitro dimethylnitrosamine (DMN) metabolism to CO2, covalent binding (CB) of DMN metabolites to nucleic acids in liver slices, DMN demethylase (DMNase) in male rat liver microsomes or 9,000 g supernatants and CB to microsome of 9,000 g supernatant proteins. Effects of those chemicals on DMN-induced rat liver necrosis were also studied, except for DS whose preventive effect was previously reported by our laboratory. All the chemicals significantly prevented DMN-induced liver necrosis, except for MMI that had no effect. All these compounds when added to incubation mixtures containing liver slices from Sprague-Dawley rats, significantly inhibited transformation of DMN to CO2 and CB to nucleic acids and when they were injected into animals and liver slices prepared afterwards, they did so except for MMI and DMF that had no effect. None of the chemicals tested except DDTC and MMI modified CB to microsome proteins whereas the CB to 9,000 g supernatant proteins was significantly decreased by all the chemicals except MMI. DMNase activity either in microsomes or 9,000 g supernatants was significantly inhibited by all the compounds except MMI.

The effect of pre-treatment with phenobarbitone on the activation of aflatoxin B1 by rat liver.

Microsomes prepared from rats pre-treated with phenobarbitone are more effective in activating aflatoxin B1 in vitro to a metabolite which inhibits RNA polymerase than are microsomes obtained from control animals. This result is in contrast with the situation in vivo where pre-treatment with phenobarbitone protects against inhibition of RNA synthesis by aflatoxin B1. The hypothesis is advanced that, in vivo, the activation of aflatoxin B1 which is significant in terms of inhibition of nucleic acid synthesis largely occurs on the outer nuclear membrane, and that by increasing activation by the microsomes, phenobarbitone pre-treatment reduces the amount of aflatoxin B1 available for the nuclear activation.