Synergistic effect ofSacoglottis gabonensis bark extract,

Aflatoxin B₁ metabolism was studied using microsomal and cytosolic fractions isolated from weanling male Fischer F344 rats given in drinking water for 7 days an aqueous extract ofSacoglottis gabonensis bark, 0.1% ethanol solution, or a solution containing both extract and ethanolad libitum. Microsomal production of aflatoxin B₁-dihydrodiol, aflatoxin Q₁, aflatoxin M₁, aflatoxin Pi and proteinaflatoxin adduct formation, and cytosolic aflatoxin B₁-glutathione conjugation were assayed. Pretreatment with the extract alone or together with ethanol caused significant increases in aflatoxin M₁ production as compared to controls given only water, but aflatoxin Q₁ production was enhanced only by pretreatment with both extract and ethanol. All the three treatments caused significant reductions in liver glutathione content. The highest aflatoxin B₁ metabolising activity as determined by aflatoxin M₁ and aflatoxin Q₁ production was observed in rats pretreated with both ethanol and the extract, suggesting synergism. The findings suggest that at relatively mild doses,S. gabonensis extract alone or in concert with ethanol may influence response to aflatoxin.     

Methodische Untersuchungen zur stoffwechselorientierten Lysinbedarfsbestimmung an Broilerküken

Broiler chicks were divided into five groups and fed starter mash from the first day after hatching. The first group feed (control) was mycotoxin free, whereas the mycotoxins sterigmatocystin (350 ppb) and aflatoxin B, (100 ppb) were added to the second group diet, patulin (100 ppb) and aflatoxin B, (100 ppb) to the third group feed, penicillic acid (850 ppb) and aflatoxin B, (100 ppb) to the fourth group, and aflatoxins B_2a (0.9 ppb) + G_2α (25 ppb) + M₁ (0.9 ppb) + M₂ (1 ppb) to the fifth group. This contaminated feeding lasted for four weeks followed by another four weeks as recovery period during which all groups fed finishing mash without mycotoxins.

At the end of the experiment, the chickens of groups two, three, four and five were significantly lower in body weight and feed conversion and reflected higher mortality rates than those of the control group.     

Evaluation of the mycological status of luncheon meat with special reference to aflatoxigenic moulds and aflatoxin residues

The luncheon meat samples analyzed, which were produced locally by the two main luncheon meat producing companies in Egypt were relatively highly contaminated either by moulds and yeasts in general, aflatoxigenic species and aflatoxin residues in particular. The most frequently encountered fungi from the samples were yeasts, Aspergillus niger, A. flavus, Penicillium chrysogenum, Rhizopus stolonifer, Mucor circinelloides. Less common were Cladosporium sphaerospermum, Alternaria alternata, Mycosphaerella tassiana, P. aurantiogriseum and P. oxalicum. The most important aflatoxigenic species, A. flavus, was isolated frequently. It was 10% of the total fungal isolates from both samples of the two companies. Seven luncheon meat samples out of 50 analyzed were positive for aflatoxin B₁ or B₁ and G₁, while all samples were negative for aflatoxins B₂, G₂, M₁ and M₂. Aflatoxin B₁ was detected only in 4 and 3 samples out of 25 analyzed from each of company A and B, respectively. The highest detectable level, 11.1 ppb, was recorded in a sample from company B and the least, 0.5 ppb, in a sample from company A. Aflatoxin G₁, at concentration of 3.2 ppb, was detected in only one sample of the aflatoxin B₁ – contaminated 3 samples of company B: this sample also had the highest level of aflatoxin B₁. Some luncheon meat samples had higher numbers of aflatoxigenic A. flavus than others, however these samples were negative for aflatoxins. The hazardous potential of such contamination will be discussed. This revised version was published online in June 2006 with corrections to the Cover Date.     

Dillapiol and Apiol as Specific Inhibitors of the Biosynthesis of Aflatoxin G1 in Aspergillus parasiticus

Dillapiol was isolated from the essential oil of dill as a specific inhibitor of aflatoxin G₁ production. It inhibited aflatoxin G₁ production by Aspergillus parasiticus with an IC₅₀ value of 0.15 μM without inhibiting aflatoxin B₁ production or fungal growth. Apiol and myristicin, congeners of dillapiol, showed similar activity with IC₅₀ values of 0.24 and 3.5 μM, respectively.     

Effect of temperature on production of aflatoxin on rice by Aspergillus flavus

Summary The effect of temperature on formation of aflatoxin on solid substrate (rice) byAspergillus flavus NRRL 2999 has been studied in some detail. The optimum temperature for production of both aflatoxin B₁ and G₁ under the conditions employed is 28° C. Comparable yields of B₁ were obtained at 32° C, but considerably less G₁ was produced at this temperature. Both B₁ and G₁ were found in lesser amounts at temperatures above 32° C, and the aflatoxin content of rice incubated at 37° C was low (300–700 ppb) even though growth was good.Reducing the temperature from 28° to 15° C resulted in progressively less aflatoxin, but 100 ppb of B₁ was detected in cultures incubated 3 weeks at 11° C. No aflatoxin was produced at 8° C.The ratio of the four aflatoxins is affected by temperature. At the lower temperatures, essentially equal amounts of aflatoxin B₁ and G₁ were produced, whereas at 28° C, approximately four times as much B₁ was detected as G₁. At the higher temperatures, relatively less G was formed, until at 37° C, less than 10 ppb was detected.This is a laboratory of the Northern Utilization Research and Development Division, Agricultural Research Service, U.S. Department of Agriculture.     

Aflatoxin B<Subscript>1</Subscript> Contamination of Traditionally Processed Peanuts Butter for Human Consumption in Sudan

A survey was carried out to detect the presence of aflatoxin B₁ in 60 duplicated samples (120 samples) of peanuts butter purchased from the local markets and other traditionally prepared and distributed by the street sellers in Khartoum state, Sudan. AflaTest-P affinity column was used to extract the toxin from the samples, and the concentration was measured by calibrated Vicam fluorometer. Aflatoxin B₁ was detected at variable levels in 100% of the screened samples. Traditionally prepared samples showed the highest incidence of aflatoxin B₁ which is above the internationally regulated tolerance levels (5–20 ppb). The means and the ranges of the aflatoxin B₁ recovered were as follows: 63.9 ppb (29–128 ppb), 54.5 ppb (21–131 ppb) and 101 ppb (17–170 ppb) for samples collected from Khartoum, Khartoum North and Omdurman areas, respectively. Samples from retail stores presented relatively low aflatoxin B₁ incidences 14.5 ppb (1–57 ppb), but only 30% of the samples revealed aflatoxin level below 10 ppb. Laboratory segregated and carefully prepared butter from good grade nuts showed the lowest levels of this toxin (3.3 ppb; 2–6 ppb). The results showed that peanuts butter prepared by the street sellers and distributed by the retail stores are evidently hazardous to human health. There is therefore urgent need for strong form of quality control measures and public awareness. The use of excellent grade peanuts and care during processing and storage are priority.     

Degradation products from aflatoxin B1 byCorynebacterium rubrum,Aspergillus niger,Trichoderma viride andMucor ambiguus

Summary Degradation of aflatoxin B₁ byCorynebacterium rubrum and byAspergillus niger was analysed by adding¹⁴C-labeled aflatoxin B₁ to cultures of these microorganisms. Two blue fluorescent compounds, formed byA. niger from aflatoxin B₁ with R_f-values 0.42 and 0.48 (R_f of aflatoxin B₁=0.54) were accumulated and characterized by UV-, fluorescence and mass spectrometry. Based on their properties both products were identified to be aflatoxin R_o. Under the same conditionsMucor ambiguus andTrichoderma viride also produced aflatoxin R_o.     

Natural occurrence of aflatoxins and ochratoxin a in corn and barley from mazandaran and golestan in north provinces of I. R. Iran

Fourteen barley and nine corn samples, destined for animal feed, collected from Golestan and Mazandaran provinces in the north of Islamic Republic of Iran (I. R. Iran) were analysed for aflatoxins (AF) and ochratoxin A (OA) by high performance liquid chromatography. In corn samples, aflatoxin B₁ (AFB₁) and aflatoxin B₂ (AFB₂) were detected in 8 (88.8%) and 6 (66.6%) samples at a mean level of 15.83 and 2.99 ppb (median 1.72 and 1 ppb), respectively. None of the corn samples contained detectable amounts of aflatoxin G₁ (AFG₁) and aflatoxin G₂ (AFG₂). Only one of the AF-contaminated samples was co-contaminated with OA at a concentration of 0.35 ppb. This is the first report concerning natural occurrence of OA and co-occurrence with AF in corn samples of north of I. R. Iran.     

Inhibitory effect of hena (Lawsonia inermis leaves) and carrot root on aflatoxin production byAspergillus parasiticus

Experiments were undertaken to evaluate the effect of some natural products (hena, and carrot root) on growth and aflatoxins production byAspergillus parasiticus FRR 2752. Powdered hena (0.5 and 5%) inhibited mycelial growth and delayed 1 sporulation ofA parasiticus during 7 days. The inhibition of growth was increased with increasing the added amount. Aflatoxins production byA parasiticus was reduced with 40–100% in the presence of hena (Lawsonia inermis leaves). Carrot root extract stimulated the fungal growth and aflatoxin production, whereas carrot root fibers slightly enriched fungal growth, inhibited aflatoxins production (B₁, G₁, and G₂), but there was no inhibition of aflatoxin B₂ production byA parasiticus.     

Aflatoxin and Ochratoxin — a contamination of dried figs (Ficus carina L) from the 1988 crop

The study examines the occurrence of aflatoxin and ochratoxin A in the !988 dried figs crop. Mycotoxin content, moisture, and a_w (water activity) were analyzed in a total of 103 fig samples collected from various orchards and different stages of fig processing. Aflatoxins (B₁, B₂, G₁, and G₂) were present in 29% of the samples examined at 0.5–63.0, 0.5–37.7, 0.5–78.3, and 0.5–12.5μ/kg, respectively. Ochratoxin A was detected in only 3% of the samples at 5.2–8.3 μ/kg. The moisture (and a_w) values of the fruits were found suitable for mycotoxin formation in firm ripened and shrivelled figs.     

Incidence of aflatoxin producing strains and aflatoxin contamination in dry fruit slices of quinces (Cydonia oblonga Mill.) from the Indian State of Jammu and Kashmir

An investigation was undertaken to obtain data on the occurrence of aflatoxins and the aflatoxin producing potential of Aspergillus flavus strains isolated from dry fruit slices of quinces produced in jammu and Kashmir, India. A total of 147 A. flavus isolates recovered from dr fruit slices were grown in liquid rice flour medium and screened for the production of various aflatoxins by thin layer chromatography. The results showed that 23.14% of the tested isolates were aflatoxigenic, producing aflatoxins B₁and B₂ in varying amounts. Aflatoxins G₁ and G₂ were not detected. All 25 of the investigated market samples were also found to be aflatoxin B₁ positive and the level of contamination ranged from 96 to 8164 g/kg of the dry fruit which is quite high in comparison to the permissible level of 30 ppb. As per these results biochemical composition of dry fruit slices of quinces, along with climatic conditions seem to be very favourable for aflatoxin production by the toxigenic A. flavus strains. Therefore,monitoring of aflatoxins in dry fruit slices of quincesis recommended for this region.This revised version was published online in October 2005 with corrections to the Cover Date.     

Survey of aflatoxins and ochratoxin A in stored tubers ofCyperus esculentus L.

The mold incidence, moisture contents, pH and levels of mycotoxins (aflatoxins B₁, G₁ and ochratoxin A) on/of/in rootstock snack (tubers ofCyperus esculentus L.) samples were monitored during a 150-day storage period. Whereas the mold incidence, moisture and mycotoxin levels increased with storage time, the pH declined during the same period. Altogether, 12 fungal species, mostly toxigenic, includingAspergillus flavus, A. parasiticus andA. ochraceus were isolated. At collection period only 3 of the 9 snack samples analysed contained trace amounts of aflatoxins. By 120th day, all the 9 samples were contaminated and the average levels were 454 and 80 ppb for aflatoxin B₁ and aflatoxin G₁ respectively on the 150th day. Ochratoxin A was not detected before 120th day and then only at low levels, occuring in a maximum of four samples and ranging between 10 and 80 ppb.     

Endothelin-1 Binding to Endothelin Receptors in the Rat Anterior Pituitary Gland: Interaction in the Recognition of Endothelin-1 Between ETA and ETB Receptors

1. ¹²⁵I-Endothelin (ET)-1 binding to the rat anterior pituitary gland was saturable and single, with a K _d of 71 pM and a B _max of 120 fmol/mg.2. When 1.0 M BQ-123 (ET_A antagonist) was added to the incubation buffer, the binding parameters were 8.3 pM and 8.0 fmol/mg, whereas 10 nM sarafotoxin S6c (ET_Bagonist) exerted little change in these binding parameters (K _d,72pM;B _max, 110 fmol/mg).3. ET_B receptor-related compounds such as sarafotoxin S6c, ET-3, IRL1620, and BQ-788 competitively inhibited ¹²⁵I-ET-1 binding, only when 1.0 M BQ-123 was present in the incubation buffer.4. Thus, the ET_B receptor is capable of binding ET-1 when the ET_A receptor is being occupied by BQ-123. A collaboration mechanism between the ET_A and the ET_B receptor may function in the recognition of ET-1, a typical bivalent ligand.     

The effects of sodium and potassium on ouabain binding by human erythrocytes

Ouabain binding by the human erythrocyte membrane is reversible, exhibits a high degree of chemical specificity, and can be detected at ouabain concentrations as low as 1 x 10^-10 M. The relation between ouabain binding and ouabain concentration can be described by a rectangular hyperbola permitting determination of the maximal binding (B _max) and the ouabain concentration at which ouabain binding is half-maximal (K_B). Reducing the external sodium concentration increased K_B, while reducing the external potassium concentration decreased K_B. Neither cation altered B _max The reciprocal of K_B was a linear function of the sodium concentration at sodium concentrations ranging from 0 to 150 mM. Conversely, the relation between the reciprocal of K_B and the external potassium concentration was nonlinear, and raising the potassium concentration above 4 mM produced no further increase in K_B. These results are compatible with a model which postulates that the erythrocyte membrane contains a finite number of receptors each composed of a glycoside-binding site and a cation-binding site. When sodium occupies the cation-binding site, the affinity of the glycoside site for ouabain is increased; when potassium occupies the cation-binding site the affinity of the glycoside site for ouabain is decreased.     

Mycoflora and aflatoxins in a West African corn-groundnut based convenience food

A total of 14 fungal species, mostly toxigenic, were isolated from 50 samples of donkwa snack obtained from 16 producers. All of the isolates recorded substantial growth, though at varying rates, on the 2% snack agar provided. They also induced a reduction in the oil and an increase in free fatty acids of the substrate suggesting their participatory roles in deterioration. Most of the snack samples analysed contained initial amounts of aflatoxins above the safe permissible level (30 ppb). The initial toxin levels increased substantially with storage time under 79.5, 89.5 and 100% ambient relative humidities but increased only slightly when samples were kept at 71% relative humidity. Almost constant toxin levels were recorded throughout the study period under 51% relative humidity. Accumulation of aflatoxin B₁ in samples was most enhanced at 89.5% relative humidity. Comparatively, greater amounts of aflatoxin B₁ accumulated under all conditions than the amounts recorded for aflatoxin G₁.     

Comparative metabolic conversion of aflatoxin B1 to M1 and Q1 by monkey, rat and chicken liver

We studied the $\text{in vitro}$ metabolish of flatoxin B₁ by liver microsomal preparations from monkey, rat and chicken. With all these species, both the previously recognized metabolite aflatoxin M₁ as well as the newly identified aflatoxin Q₁ were produced from the aflatoxin B₁ substrate. Aflatoxin Q₁ is an isomer of aflatoxin M₁ (with the hydroxyl on the carbon β to the carbonyl of the cyclopentenone ring) which we discovered recently in rat and monkey liver incubations with aflatoxin B₁. In our incubations we did not detect aflatoxin P₁ which has been reported as a major metabolite of aflatoxin B₁$\text{in vivo}$ in the monkey.In general the conversion to aflatoxin M₁ was comparable among the different species (1–3% of the substrate) except in the chicken in which it was lower (0.1–0.3%). Also the conversion to Q₁ was comparable to or slightly higher than the conversion to M₁ with rat and chicken liver but the conversion to Q₁ with the monkey liver was outstandingly high, accounting for 19–52% of the substrate in three species of monkeys tested.     

Mycotoxins and mycotoxigenic moulds in nuts and sunflower seeds for human consumption

A survey was carried out to obtain data on the occurrence of mycotoxins and the mycotoxin-producing potential of fungi isolated from nuts (almonds, peanuts, hazelnuts, pistachio nuts) and sunflower seeds in Spain. Thin-layer chromatography was used to separate the toxins. Aflatoxins were detected in one sample of almonds (95 ppb aflatoxin B₁ and 15 ppb aflaxtoxin B₂) and in one sample of peanuts at a level below 10 ppb of aflatoxin B1. 100% of samples showed variable incidence of fungal contamination. The predominant fungi present in samples were Penicillium spp, Aspergillus niger, A. flavus, A. glaucus and Rhizopus spp. The results showed that isolates of different species were able to produce aflatoxins B₁, B₂, G₁, and G₂, sterigmatocystin, ochratoxin A, patulin, citrinin, penicillic acid, zearalenone, and griseofulvin.     

Enhancement of aflatoxin B1 cytotoxicity in differentiated rat hepatoma cultures by a prior glucocorticoid treatment of the monolayer.

The cytotoxic effect of aflatoxin B₁ on cultures of a differentiated rat hepatoma cell line, Faza 967, has been evaluated by scoring the surviving colonies two weeks after briefly exposing the freshly plated cells to the mycotoxin. At the lowest concentration, aflatoxin B₁ exhibits no toxicity, unless the cultures have been pretreated with dexamethasone. HF-1, an hepatoma hybrid cell line exhibiting extinction of the hepatic functions and HF1-4, its subclone, that reexpresses all of these functions, have been compared. A 6hrs exposure to 60ng/ml aflatoxin B₁ is not toxic for HF₁ even after an hormonal treatment, while dexamethasone enhances the effect on HF₁-4. Glucocorticoïds have been shown previously to induce, in the differentiated clones, the hydroxylation of bile acid - a cytochrome P-450-mediated reaction ; in contrast, 3-methylcholanthrene, an inducer of benzopyrene hydroxylase in hepatoma cultures, is without effect on bile acid metabolism and on aflatoxin B₁ cytotoxicity. These results suggest that in the differentiated hepatoma cells, aflatoxin B₁ is converted into a cytotoxic metabolite by a glucocorticoïd-induced monooxygenase belonging to the cytochrome P-450-related group.     

Comparison of the ability of three Aspergillus strains to form aflatoxins on bakery products and on nutrient agar

The growth of Aspergillus parasiticus NRRL 2999, A. parasiticus NRRL 3000 and A. flavus NRRL 3251 on whole wheat bread and on cake (Rührkuchen) was compared and the formation of the aflatoxins B₁, B₂, G₁, G₂ and M₁ on these substrates and, for purpose of comparison, on malt extract agar was determined. On cake the moulds grew better than on bread and formed the highest yields of aflatoxins. Malt extract agar was the most unfavourable substrate for toxin production. The ratio M₁/B₁ on bread and cake was in the order of 0.1–0.4 and was higher than the data reported for grains. The highest yields of aflatoxin B₁ (1.0 g/g) were produced by A. flavus NRRL 3251 on cake.     

Correlation of Lung Collapse and Gas Exchange - A Computer Tomographic Study in Sheep and Pigs with Atelectasis in Otherwise Normal Lungs

Background

Atelectasis can provoke pulmonary and non-pulmonary complications after general anaesthesia. Unfortunately, there is no instrument to estimate atelectasis and prompt changes of mechanical ventilation during general anaesthesia. Although arterial partial pressure of oxygen (PaO₂) and intrapulmonary shunt have both been suggested to correlate with atelectasis, studies yielded inconsistent results. Therefore, we investigated these correlations.

Methods

Shunt, PaO₂ and atelectasis were measured in 11 sheep and 23 pigs with otherwise normal lungs. In pigs, contrasting measurements were available 12 hours after induction of acute respiratory distress syndrome (ARDS). Atelectasis was calculated by computed tomography relative to total lung mass (M_total). We logarithmically transformed PaO₂ (lnPaO₂) to linearize its relationships with shunt and atelectasis. Data are given as median (interquartile range).

Results

M_total was 768 (715–884) g in sheep and 543 (503–583) g in pigs. Atelectasis was 26 (16–47) % in sheep and 18 (13–23) % in pigs. PaO₂ (FiO₂ = 1.0) was 242 (106–414) mmHg in sheep and 480 (437–514) mmHg in pigs. Shunt was 39 (29–51) % in sheep and 15 (11–20) % in pigs. Atelectasis correlated closely with lnPaO₂ (R² = 0.78) and shunt (R² = 0.79) in sheep (P-values<0.0001). The correlation of atelectasis with lnPaO₂ (R² = 0.63) and shunt (R² = 0.34) was weaker in pigs, but R² increased to 0.71 for lnPaO₂ and 0.72 for shunt 12 hours after induction of ARDS. In both, sheep and pigs, changes in atelectasis correlated strongly with corresponding changes in lnPaO₂ and shunt.

Discussion and Conclusion

In lung-healthy sheep, atelectasis correlates closely with lnPaO₂ and shunt, when blood gases are measured during ventilation with pure oxygen. In lung-healthy pigs, these correlations were significantly weaker, likely because pigs have stronger hypoxic pulmonary vasoconstriction (HPV) than sheep and humans. Nevertheless, correlations improved also in pigs after blunting of HPV during ARDS. In humans, the observed relationships may aid in assessing anaesthesia-related atelectasis.