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Biomedical subjects

M A Mayo

Publications and source records attributed to M A Mayo.

At least 19 recordsLinked to original sources
PubMed2002

Development and application of an indirect competitive enzyme-linked immunoassay for aflatoxin m(1) in milk and milk-based confectionery.

High-titer rabbit polyclonal antibodies to aflatoxin M(1) (AFM1) were produced by utilizing AFM1-bovine serum albumin (BSA) conjugate as an immunogen. An indirect competitive enzyme-linked immunosorbent assay was standardized for estimating AFM1 in milk and milk products. To avoid the influence of interfering substances present in the milk samples, it was necessary to prepare AFM1 standards in methanol extracts of certified reference material (CRM) not containing detectable AFM1 (< 0.05 ng/g). The reliability of the procedure was assessed by using CRM with AFM1 concentrations of < 0.5 and 0.76 ng/g. Also, assays of milk samples mixed with AFM1 ranging in concentration between 0.5 and 50 ng/L gave recoveries of > 93%. The relative cross-reactivity with aflatoxins (AF) and ochratoxin A, assessed as the amount of AFM1 necessary to cause 50% inhibition of binding, was 5% for AFB1 and much less for AFB2, AFG1, and AFG2; there was no reaction with ochratoxin A. AFM1 contamination was measured in retail milk and milk products collected from rural and periurban areas in Andhra Pradesh, India. Of 280 milk samples tested, 146 were found to contain < 0.5 ng/mL of AFM1; in 80 samples it varied from 0.6 to 15 ng/mL, in 42 samples from 16 to 30 ng/mL, and in 12 samples from 31 to 48 ng/mL. Most of the milk samples that contained high AFM1 concentrations were obtained from periurban locations. The results revealed a significant exposure of humans to AFM1 levels in India and thus highlight the need for awareness of risk among milk producers and consumers.

Aflatoxin M1↗
PubMed2002

Occurrence of aflatoxins and ochratoxin A in Indian poultry feeds.

From 1998 to 2001, 216 ingredients intended for incorporation into chicken feed, which included groundnut cake, maize, millets, rice bran, sorghum, soybean, sunflower, and mixed feeds, were assayed for aflatoxins and ochratoxin A contamination using an indirect competitive enzyme-linked immunosorbent assay. Thirty-eight percent of the samples were contaminated with aflatoxins and 6% with ochratoxin A. The incidence scores of aflatoxin contamination in excess of 10 microg/kg were 41 of 95 for maize, 18 of 30 for mixed feeds, 10 of 37 for groundnut, 6 of 29 for sorghum, 5 of 10 for sunflower, 3 of 14 for rice bran, and 1 of 8 for millet. Ochratoxin A contamination, in excess of 10 microg/kg, was found in 9 of 29 sorghum samples, 1 of 27 groundnut samples, 1 of 14 rice bran samples, 1 of 10 sunflower samples, and 2 of 8 millet samples. Ochratoxin A was not found in maize and mixed feeds. None of the three soybean samples contained ochratoxin A. This is the first report, to our knowledge, of co-occurrence of aflatoxins and ochratoxin A in Indian poultry feeds. The results confirm the importance of analysis of ingredients before incorporating them into mixed feeds.

Aflatoxins↗
PubMed2002

[Hemodynamic modifications in splenic circulation studied by echo-Doppler during pregnancy].

INTRODUCTION: Pregnancy produces multiple changes in the mother's body, most of which have been studied. However, changes in hepatosplenic circulation are not well-known. The routine use of ultrasonography and of echo-Doppler has created new possibilities for the knowledge of splenic circulation during pregnancy. MATERIAL AND METHOD: We studied 30 healthy pregnant women who had given their informed consent. To evaluate the morphological and hemodynamic changes that might occur in the splenic vessels during pregnancy and immediate puerperium, laboratory investigations, obstetric and hepatic ultrasonography, and hepatosplenic echo-Doppler were performed between weeks 8-12, 20-24, and 32-36, as well as in the immediate puerperium. RESULTS: The caliber of the vena porta and its tributaries, as well as that of its intrahepatic branches, increased while the caliber of the suprahepatic vessels slightly decreased during pregnancy. The hemodynamic changes detected by Doppler ultrasonography were: progressive flattening of the pulsed Doppler trace of the suprahepatic vessels during the course of pregnancy; a progressive reduction in mean portal velocity, which was more marked in the third trimester, and a decrease in the markers of resistance in the hepatic artery and superior mesenteric artery. CONCLUSIONS: Hemodynamic changes in hepatosplenic circulation are produced during pregnancy that can be safely and effectively evaluated in real time by ultrasonography and echo-Doppler. Knowledge of these changes is required to evaluate these vessels in pathological conditions.

Female↗
PubMed2001

Umbravirus gene expression helps potato leafroll virus to invade mesophyll tissues and to be transmitted mechanically between plants.

Potato leafroll virus (PLRV) was mechanically transmissible when inocula also contained the umbravirus Pea enation mosaic virus-2 (PEMV-2). In plants infected with PLRV and PEMV-2, PLRV accumulated in clusters of mesophyll cells in both inoculated and systemically infected leaves. No transmissions were obtained by coinoculation with Potato virus Y, Potato virus X (PVX), Tobacco mosaic virus, or Cucumber mosaic virus (CMV), although PLRV was transmissible from mixtures with CMV(ORF4) (a recombinant that contained the movement protein (MP) gene of the umbravirus Groundnut rosette virus (GRV) in place of the CMV MP gene). In contrast, neither a recombinant PVX that expressed GRV MP nor a mutant of CMV(ORF4), in which the CMV 2b gene was untranslatable, was able to help PLRV transmission. Possibly both a cell-to-cell movement function and counterdefense mechanisms such as those that block posttranscriptional gene silencing are involved in movement of PLRV within plants and its mechanical transmission between plants.

Arachis↗
PubMed2001

Phage-displayed peptides that mimic aflatoxin B1 in serological reactivity.

AIMS: To test phage-displayed random peptide libraries as sources of peptides that mimic the binding of aflatoxin B1 to monoclonal antibodies raised against the toxin. METHODS AND RESULTS: For two of the three MAbs tested, clones were obtained by panning, producing phage that bound specifically to MAb 13D1-1D9 (MAb 24; specific for aflatoxins B1 and G1) and MAb 6E12-1E9 (MAb 13; specific for aflatoxins B1, G1 and B2) in ELISA. The amino acid sequences of the binding peptides varied. Those binding to MAb 24 contained the sequence of '...YMD...', and those that bound to MAb 13 contained the dipeptide 'PW'. Mimotope phage was used in a competition ELISA format for assaying aflatoxin concentrations. CONCLUSION: The results show that mimotope preparations are effective substitutes for pure toxin in these ELISA procedures. SIGNIFICANCE AND IMPACT OF THE STUDY: These results should contribute significantly to enhancing the safety and diminishing the costs of aflatoxin assays.

Aflatoxin B1↗
PubMed2001

Occurrence of ochratoxin A in black pepper, coriander, ginger and turmeric in India.

Ochratoxin A (OA) contamination of black pepper, coriander seeds, powdered ginger and turmeric powder was estimated using indirect competitive ELISA. Samples (1 g) were extracted with 0.5% potassium chloride (KCl) in 70% methanol (5 ml) and diluted subsequently to give two-fold to ten-fold step-wise dilutions in phosphate-buffered saline containing 0.05% Tween 20 and 0.2% bovine serum albumin (PBS-T BSA). For extracts from the spices analysed, ELISA estimates of OA concentrations were compared with those made by HPLC. All estimates were within 1-2 standard deviation of the ELISA values. More than 90% of OA added to spice samples was recovered from samples containing between 5 and 100 microg/kg OA. Extracts of OA-free spice samples contained substances that interfered with ELISA, presumably because of non-specific reactions. This effect was avoided by preparing all the test solutions in extracts of OA-free spice samples. In 126 samples obtained from retail shops, OA was found to exceed 10 microg/kg in 14 (in the range of 15-69 microg/kg) of 26 black pepper samples, 20 (in the range of 10-51 microg/kg) of 50 coriander samples, two (23 microg/kg and 80 microg/kg) of 25 ginger samples and nine (in the range of 11-102 microg/kg) of 25 turmeric samples. This is the first record in India of the occurrence of OA in what are some of the most widely used spices in Indian cooking.

Apiaceae↗
PubMed2000

The nucleotide sequence of Indian peanut clump virus RNA 2: sequence comparisons among pecluviruses.

The RNA-2 molecule of an isolate of the L serotype of Indian peanut clump virus (IPCV) was shown to consist of 4,290 nucleotides with five open reading frames (ORF). The arrangement of the ORFs resembled that in RNA-2 of Peanut clump virus (PCV) from West Africa. The proteins encoded by the ORFs in IPCV-L RNA are between 32% and 93% identical to those encoded by PCV RNA. Partial sequence data for the RNA-2 of isolates of the H and T serotypes of IPCV show that the coat and P40 proteins encoded by the 5'-most ORFs of RNA-2 of IPCV-L, IPCV-H and IPCV-T are as similar to each other as any is to the corresponding proteins of PCV. A conserved motif 'F-E-x6-W' is present near the C-termini of the coat proteins of all three IPCV serotypes and of PCV, as it is in the coat proteins of other viruses that have rod-shaped particles, such as Tobacco mosaic virus and Tobacco rattle virus. The results support the distinction of IPCV and PCV as separate virus species, but also raise the question of how the serotypes of IPCV should be classified.

Amino Acid Sequence↗