Mycotoxins in a changing global environment--a review.

Mycotoxins are toxic metabolites produced by fungal species that commonly contaminate staple foods and feeds. They represent an unavoidable problem due to their presence in globally consumed cereals such as rice, maize and wheat. Most mycotoxins are immunosuppressive agents and some are carcinogens, hepatotoxins, nephrotoxins, and neurotoxins. Worldwide trends envision a stricter control of mycotoxins, however, the changing global environment may not be the ideal setting to control and reduce the exposure to these toxins. Although new technologies allow us to inspect the multi-mycotoxin presence in foods, new sources of exposure, gaps in knowledge of mycotoxins interactions, appearance of "emergent" mycotoxins and elucidation of consequent health effects can complicate their control even more. While humans are adapting to cope with environmental changes, such as food scarcity, decreased food quality, mycotoxin regulations, crop production and seasonality, and other climate related modifications, fungal species are also adapting and increased cases of mycotoxin adverse health effects are likely to occur in the future. To guarantee access to quality food for all, we need a way to balance global mycotoxin standards with the realistic feasibility of reaching them, considering limitations of producers and designing strategies to reduce mycotoxin exposure based on sound research.

Silencing of essential genes by RNA interference in Haemonchus contortus.

In this study we assessed three technologies for silencing gene expression by RNA interference (RNAi) in the sheep parasitic nematode Haemonchus contortus. We chose as targets five genes that are essential in Caenorhabditis elegans (mitr-1, pat-12, vha-19, glf-1 and noah-1), orthologues of which are present and expressed in H. contortus, plus four genes previously tested by RNAi in H. contortus (ubiquitin, tubulin, paramyosin, tropomyosin). To introduce double-stranded RNA (dsRNA) into the nematodes we tested (1) feeding free-living stages of H. contortus with Escherichia coli that express dsRNA targetting the test genes; (2) electroporation of dsRNA into H. contortus eggs or larvae; and (3) soaking adult H. contortus in dsRNA. For each gene tested we observed reduced levels of mRNA in the treated nematodes, except for some electroporation conditions. We did not observe any phenotypic changes in the worms in the electroporation or dsRNA soaking experiments. The feeding method, however, elicited observable changes in the development and viability of larvae for five of the eight genes tested, including the 'essential' genes, Hc-pat-12, Hc-vha-19 and Hc-glf-1. We recommend the E. coli feeding method for RNAi in H. contortus and provide recommendations for future research directions for RNAi in this species.

Calcium montmorillonite clay reduces urinary biomarkers of fumonisin B1 exposure in rats and humans.

Fumonisin B1 (FB1) is often a co-contaminant with aflatoxin (AF) in grains and may enhance AF's carcinogenicity by acting as a cancer promoter. Calcium montmorillonite (i.e. NovaSil, NS) is a possible dietary intervention to help decrease chronic aflatoxin exposure where populations are at risk. Previous studies show that an oral dose of NS clay was able to reduce AF exposure in a Ghanaian population. In vitro analyses from our laboratory indicated that FB1 (like aflatoxin) could also be sorbed onto the surfaces of NS. Hence, our objectives were to evaluate the efficacy of NS clay to reduce urinary FB1 in a rodent model and then in a human population highly exposed to AF. In the rodent model, male Fisher rats were randomly assigned to either FB1 control, FB1 + 2% NS or absolute control group. FB1 alone or with clay was given as a single dose by gavage. For the human trial, participants received NS (1.5 or 3 g day⁻¹) or placebo (1.5 g day⁻¹) for 3 months. Urines from weeks 8 and 10 were collected from the study participants for analysis. In rats, NS significantly reduced urinary FB1 biomarker by 20% in 24 h and 50% after 48 h compared to controls. In the humans, 56% of the urine samples analysed (n = 186) had detectable levels of FB1. Median urinary FB1 levels were significantly (p < 0.05) decreased by >90% in the high dose NS group (3 g day⁻¹) compared to the placebo. This work indicates that our study participants in Ghana were exposed to FB1 (in addition to AFs) from the diet. Moreover, earlier studies have shown conclusively that NS reduces the bioavailability of AF and the findings from this study suggest that NS clay also reduces the bioavailability FB1. This is important since AF is a proven dietary risk factor for hepatocellular carcinoma (HCC) in humans and FB1 is suspected to be a dietary risk factor for HCC and oesophageal cancer in humans.

High proton conductivity of water channels in a highly ordered nanowire.

A proton-conductive material based on a crystalline assembly of trimesic acid and melamine (TMA⋅M, see picture) is reported. Because of the ordered structure of the assembly, the water-saturated proton conductivity for the TMA⋅M assembly is 5.5 S cm(-1) , which is the highest proton conductivity measured to date. This exceptionally high conductivity and low-cost fabrication of the material make applications feasible for fuel-cell devices.

Characterization and Safety of Uniform Particle Size NovaSil Clay as a Potential Aflatoxin Enterosorbent.

NovaSil (NS) clay, a common anti-caking agent in animal feeds, has been shown to adsorb aflatoxins and diminish their bioavailability in multiple animal models. The safety of long-term dietary exposure to NS has also been demonstrated in a 6-month sub-chronic study in rats and in a 3-month intervention in humans highly exposed to aflatoxins. Uniform particle size NovaSil (UPSN) is a refined material derived from parent NS; it contains lower levels of dioxins/furans, and has been selected for a more consistent uniform particle size. Nevertheless, the efficacy and potential safety/toxicity of UPSN for long term-use has not yet been determined. In this research, 4-week-old male and female Sprague Dawley rats were fed rations free of clay (control) and containing UPSN at low dose (0.25%) and high dose (2%) for 13 weeks. AFB(1) sorption characteristics remained the same for both clays. When compared to the control, total body weight gain was unaffected in either sex at the doses tested. No UPSN-dependent differences in relative organ weights or gross appearance were observed. Isolated differences between UPSN groups and the control were observed for some biochemical parameters and selected vitamins and minerals. None of these differences were dose-dependent, and all parameters fell between ranges reported as normal for rats less than 6 month old. The Na/K ratio, Na and vitamin E concentrations were the only parameters that were increased in both males and females in the low dose and high dose UPSN groups. Serum Zn levels in males from the 2% UPSN treatment were lower compared to the control. Serum K levels were lower in the males of UPSN groups than in the control. However, neither Na/K ratio, K, nor Zn values were dose dependent and fell outside ranges reported as normal. These results suggest that dietary inclusion of UPSN at levels as high as 2% (w/w) does not result in overt toxicity. Nevertheless, further research on the effects of clays on Na, Zn, K and vitamin E is warranted.

In vitro and in vivo characterization of mycotoxin-binding additives used for animal feeds in Mexico.

The study was conducted to characterize and compare twelve different additives distributed in Mexico as mycotoxin binders utilizing: (1) equilibrium isothermal analysis for aflatoxin B(1) (AFB(1)) adsorption, (2) a variety of mineralogical probes, and (3) Hydra toxicity bioassay. The test additives Milbond-TX (MLB), Mycoad (MCA), Volclay FD181 (VOL), Fixat (FXT), Toxinor (TOX), Mexsil (MEX), Mycosil (MYC), Klinsil (KLS), Zeotek (ZEO), Duotek (DUO), Mycosorb (MSB), and Mycofix Plus 3.0 (MIX) were compared with NovaSil Plus (NSP). Isotherms for AFB(1) adsorption were conducted at pH 2 and pH 6.5, mimicking pH conditions in the stomach and small intestine. Mineralogical analysis included determination of swelling volume, X-ray diffraction analysis, and fractionation procedures. A Hydra vulgaris toxicity study was performed to evaluate the potential safety of the additives. Computer-generated isotherm data were fit using the Langmuir model, and parameters of Q(max) and K(d) were estimated. The most effective additives for AFB(1) at both pH conditions were NSP, MLB, MCA and VOL, while the least effective was MSB. The amounts of sand, silt and clay fractions varied among the additives. Nine of the additives showed the presence of smectite. Most of the additives were found to be non-toxic to Hydra except for the organoclays (ZEO, DUO) and MSB. In general, NSP demonstrated the highest sorption capacity in the bulk material and the different fractions. Studies to characterize these binding additives further and to evaluate their multiple mycotoxin sorption claims are ongoing.

NovaSil clay does not affect the concentrations of vitamins A and E and nutrient minerals in serum samples from Ghanaians at high risk for aflatoxicosis.

To assess the potential interference of NovaSil (NS) clay with micronutrients in humans, vitamins A and E and minerals (15 nutrient and 15 non-nutrient minerals) were measured in serum samples from a 3-month intervention trial with NS. Participants (n = 177) were randomly divided into three groups that received 3.0 g NS day(-1) (high dose, HD), 1.5 g NS day(-1) (low dose, LD), or placebo (PL). Levels of vitamins A and E in serum were comparable among the three study groups at baseline, 1 month and 3 months of NS intervention. Gender-stratified non-parametric mixed-effect model analysis showed no significant effects of dose and dose-time interaction for levels of vitamins A and E. A significant time effect was detected; however, it was limited to an increase in vitamin E in the male participants over the course of the study. No significant differences were found in levels of the nutrient and non-nutrient minerals between the HD and PL groups at baseline and 3 months of NS intervention, except for strontium levels. Strontium was significantly increased (p < 0.001) in the HD group (male = 113.65 +/- 28.00 microg l(-1); female = 116.40 +/- 24.26 microg l(-1)) compared with the PL group (male = 83.55 +/- 39.90 microg l(-1); female = 90.47 +/- 25.68 microg l(-1)) following the 3-month intervention with NS. These results, combined with safety and efficacy data, confirm that NS clay is highly effective in reducing aflatoxin exposure and acts as a selective enterosorbent that does not affect the serum concentrations of important vitamins and nutrient minerals in humans.

NovaSil clay intervention in Ghanaians at high risk for aflatoxicosis: II. Reduction in biomarkers of aflatoxin exposure in blood and urine.

The efficacy of NovaSil clay (NS) to reduce aflatoxin (AF) biomarkers of exposure was evaluated in 656 blood samples and 624 urine samples collected from study participants during a 3-month phase IIa clinical intervention trial in Ghana. NS was delivered before meals via capsules. Serum AFB (1)-albumin adduct was measured by radioimmunoassay and urinary AFM (1) metabolites were quantified by immunoaffinity-high-performance liquid chromatography (HPLC)-fluorescence methods. Levels of AFB (1) -albumin adduct in serum samples collected at baseline and at 1 month were similar (p = 0.2354 and p = 0.3645, respectively) among the placebo (PL), low dose (LD, 1.5 g NS day (-1)), and high dose (HD, 3.0 g NS day (-1)) groups. However, the levels of AFB (1)-albumin adduct at 3 months were significantly decreased in both the LD group (p < 0.0001) and the HD group (p < 0.0001) compared with levels in the PL group. Levels of AFM(1) in urine samples collected at baseline and at 1 month were not statistically different among the three study groups. However, a significant decrease (up to 58%) in the median level of AFM (1) in samples collected at 3 months was found in the HD group when compared with the median level in the PL group (p < 0.0391). In addition, significant effects were found for dose, time, and dose-time interaction with serum AFB(1)-albumin adduct and dose-time interaction with urinary AFM (1) metabolites. The results suggest that capsules containing NS clay can be used to reduce effectively the bioavailability of dietary AF based on a reduction of AF-specific biomarkers.

NovaSil clay intervention in Ghanaians at high risk for aflatoxicosis. I. Study design and clinical outcomes.

A 3-month double-blind and placebo-controlled, phase IIa clinical trial was conducted in Ghana to investigate the safety, tolerance and aflatoxin-sorption efficacy of dietary NovaSil (NS). Volunteers (507 subjects) were clinically screened to evaluate their general health, pregnancy status and blood AFB(1)-albumin adduct levels. Of these subjects, 177 were randomly assigned to three groups: high-dose (HD), low-dose (LD) and placebo-control (PL) groups receiving 3.0, 1.5 and 0 g NS day(-1) in capsules. Trained study-monitors supervised NS capsule administration to participants and recorded side-effects daily. Physical examinations were performed monthly. Blood and urine samples were collected for laboratory analysis. Approximately 92% of the participants (162 of 177) completed the study and compliance rate was over 97%. Overall, 99.5% of person x time reported no side-effects throughout the study. Mild to moderate health events ( approximately 0.5% of person x time) were recorded in some participants. Symptoms included nausea, diarrhea, heartburn and dizziness. These side-effects were statistically similar among all three groups. No significant differences were shown in hematology, liver and kidney function or electrolytes in the three groups. These findings demonstrate that NS clay is apparently safe and practical for the protection of humans against aflatoxins in populations at high risk for aflatoxicosis.

High-Q-preserving coupling between a spiral and a semicircle micro-cavity.

We present an efficient design for direct coupling between a spiral-shaped and a semicircle-shaped microcavity (micro-cavity) as an alternative to traditional evanescent wave coupling for planar integrated photonic technology. We observe the preservation of the high Q-value of the spiral oscillator when coupled to a semicircle under current injection using an AlGaAs single-quantum-well heterostructure. With slight alterations to the directly coupled micro-cavity configuration, such as coupling shape and overlap distance, the number of observed modes and output intensity are changed. AlGaAs and InGaN spiral-shaped microcavities have unidirectional emission normal to the spiral notch.

The Caenorhabditis briggsae genome contains active CbmaT1 and Tcb1 transposons.

The maT clade of transposons is a group of transposable elements intermediate in sequence and predicted protein structure to mariner and Tc transposons, with a distribution thus far limited to a few invertebrate species. We present evidence, based on searches of publicly available databases, that the nematode Caenorhabditis briggsae has several maT-like transposons, which we have designated as CbmaT elements, dispersed throughout its genome. We also describe two additional transposon sequences that probably share their evolutionary history with the CbmaT transposons. One resembles a fold back variant of a CbmaT element, with long (380-bp) inverted terminal repeats (ITRs) that show a high degree (71%) of identity to CbmaT1. The other, which shares only the 26-bp ITR sequences with one of the CbmaT variants, is present in eight nearly identical copies, but does not have a transposase gene and may therefore be cross mobilised by a CbmaT transposase. Using PCR-based mobility assays, we show that CbmaT1 transposons are capable of excising from the C. briggsae genome. CbmaT1 excised approximately 500 times less frequently than Tcb1 in the reference strain AF16, but both CbmaT1 and Tcb1 excised at extremely high frequencies in the HK105 strain. The HK105 strain also exhibited a high frequency of spontaneous induction of unc-22 mutants, suggesting that it may be a mutator strain of C. briggsae.

Ontogenetic changes in characteristics required for endothermy in juvenile black skipjack tuna (Euthynnus lineatus).

To characterize better the development of endothermy in tunas, we assessed how the abilities to generate heat and to conserve heat within the aerobic, slow-twitch (red) myotomal muscle using counter-current heat exchangers (retia) change with size in juvenile black skipjack tuna (Euthynnus lineatus) above and below the hypothesized minimum size for endothermy of 207 mm fork length (FL). Early juvenile scombrids (10-77 mm FL) collected off the Pacific coast of Panama were raised to larger sizes at the Inter-American Tropical Tuna Commission Laboratory at Achotines Bay, Panama. Evidence of central and lateral rete blood vessels was found in E. lineatus as small as 95.9 mm FL and 125 mm FL, respectively. In larger E. lineatus juveniles (up to 244 mm FL), the capacity for heat exchange increased with fork length as a result of increases in rete length, rete width and the number of vessel rows. The amount (g) of red muscle increased exponentially with fork length in both E. lineatus (105-255 mm FL) and a closely related ectothermic species, the sierra Spanish mackerel Scomberomorus sierra (151-212 mm FL), but was greater in E. lineatus at a given fork length. The specific activity (international units g(-)(1)) of the enzyme citrate synthase in red muscle, an index of tissue heat production potential, increased slightly with fork length in juvenile E. lineatus (84. 1-180 mm FL) and S. sierra (122-215 mm FL). Thus, total red muscle heat production capacity (red muscle citrate synthase activity per gram times red muscle mass in grams) increased with fork length, primarily because of the increase in red muscle mass. Below 95.9 mm FL, E. lineatus cannot maintain red muscle temperature (T(m)) above the ambient water temperature (T(a)) because juveniles of this size lack retia. Above 95.9 mm FL, the relationship between T(x) (T(m)-T(a)) and FL for E. lineatus diverges from that for the ectothermic S. sierra because of increases in the capacities for both heat production and heat retention that result in the development of endothermy.

Randomized trial of inhaled fluticasone propionate in chronic stable pulmonary sarcoidosis: a pilot study.

Pulmonary sarcoidosis is a disease in which the pathological processes are distributed along lymphatic pathways, particularly those around the bronchovascular bundles. Delivery of disease-modulating drugs by the inhaled route is therefore an attractive option. The aim of this study was to determine the efficacy of inhaled fluticasone propionate 2 mg x day(-1) in adults with stable pulmonary sarcoidosis. Forty-four adult patients (22 from each centre) were enrolled from outpatient clinics in two London teaching hospitals in a two centre, double-blind, randomized, placebo-controlled trial. Primary end points were home recordings of peak expiratory flow rate (PEFR), forced expiratory volume in one second (FEV1), and forced vital capacity (FVC). Secondary end points were symptom scores, use of rescue bronchodilator medication, and clinic values for PEFR, FEV1, FVC, forced mid-expiratory flow (FEF25-75%), diffusion capacity of the lung for carbon monoxide (DL,CO), and total lung capacity (TLC). Symptom scores of cough, breathlessness and wheeze were lower in the active treatment group, but this did not reach statistical significance, and a general health perception assessment (Short Form (SF)-36) showed a difference between active and placebo treatment. No significant differences were found between the two groups in any physiological outcome measure. No new adverse reactions were detected. The results of this pilot study do not show an objective benefit of inhaled fluticasone propionate in pulmonary sarcoidosis where the disease is stable and is controlled without the use of inhaled corticosteroids.

Specific detection of Mycobacterium paratuberculosis DNA associated with granulomatous tissue in Crohn's disease.

The role of mycobacteria, specifically Mycobacterium paratuberculosis, in Crohn's disease has aroused considerable controversy for many years. Using the ultra sensitive polymerase chain reaction some studies have reported detection of M paratuberculosis DNA in as many as 65% of Crohn's disease patients but also in patients without disease. Other studies have been negative for both groups. We therefore designed a double blind control trial to investigate the presence of mycobacterial DNA in age, sex, and tissue matched paraffin wax embedded tissues from 31 Crohn's disease tissues, 20 diseased gut control tissues, and 10 ulcerative colitis tissues. The specimens were coded and analysed blind with three separate polymerase chain reactions (PCR) based on DNA sequences specific for M paratuberculosis (IS900), M avium (RFLP type A/1) (IS901), and the Mycobacterium genus (65 kDa gene, TB600). The number of granulomata and presence of acid fast bacilli in each Crohn's disease tissue was also investigated. The sensitivity of the system was determined using similarly prepared gut tissue from an animal infected with M paratuberculosis. Four of 31 Crohn's disease tissues and none of the 30 control and ulcerative colitis derived tissues amplified M paratuberculosis DNA. Crohn's disease tissues containing granulomata were significantly more likely to amplify M paratuberculosis specific DNA on PCR than the non-Crohn's disease tissues (p = 0.02). All the positive Crohn's disease tissues contained granulomata, and none contained acid fast bacilli. Equivalent numbers of Crohn's and non-Crohn's disease tissues amplified the region of the 65 kD gene on PCR for non-specific mycobacterial DNA (11/31 and 9/30 respectively). No sections produced an amplified product with the IS901 PCR. These results suggest that few Crohn's disease gut biopsy sections contain M paratuberculosis DNA in association with granulomata. The absence of such DNA in any control and ulcerative colitic tissue strengthens the case for it having a specific association, which may be pathogenic, with Crohn's disease in this minority of patients.

Study into the ability of healthy people of small stature to satisfy the sampling requirements of breath alcohol testing instruments.

In a previous study (Gomm et al., 1991) people with a variety of respiratory diseases were tested and criteria defined for assessing their ability to provide samples for Breath Alcohol Testing Instruments. This study investigated the possible problems which may be encountered by healthy people of small stature--5ft 5in (166cm) or less--who do not suffer from a respiratory disease. This study followed the same pattern as the earlier work in that lung function (Forced Expiration Volume in One Second (FEV1) and Forced Vital Capacity (FVC)) was measured by spirometry, and Peak Expiration Flow Rate (PEFR) was measured using a Wright peak flow meter. Following the lung function measurements the subjects were requested to provide samples for Breath Alcohol Testing Instruments used by the Police in Great Britain. As with the previously reported work (Gomm et al., 1991), this study found that the FEV1 and FVC gave the most reliable indication of a person's capability of satisfying the sampling requirements of Breath Alcohol Testing Instruments, but on this occasion the PEFR also provided a good confirmatory indication. Because there were no subjects with interstitial lung diseases the values determined by this study on 48 healthy adults indicate that a healthy person of small stature should be capable of supplying a suitable breath sample if their FEV1, FVC and PEFR are greater than 2.31, 2.61 and 330 l/min respectively.

Mycobacterium tuberculosis DNA in tissue affected by sarcoidosis.

OBJECTIVE: To investigate the prevalence of Mycobacterium tuberculosis DNA in granulomatous tissues from patients with sarcoidosis and from controls matched for age, sex, and tissue by using the polymerase chain reaction. DESIGN: Single blind control trial. SUBJECTS: 16 patients with sarcoidosis who had undergone diagnostic biopsy of lung, skin, or lymph node and 16 patients with squamous cell carcinoma or Hodgkin's disease to act as controls. In addition, four lung specimens infected with M tuberculosis were included as positive controls. RESULTS: M tuberculosis DNA was present in sarcoid tissues containing granulomas from seven of the 16 patients and one of the 16 matched controls. Two of the four specimens known to be infected with M tuberculosis were positive in the controlled experiment. CONCLUSION: These figures suggest that M tuberculosis DNA is detected as readily in patients with sarcoidosis as in patients with frankly tuberculous tissues and imply that M tuberculosis may be linked to the cause of sarcoidosis.