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Biomedical subjects

J Gilbert

Publications and source records attributed to J Gilbert.

At least 325 records · Page 18Linked to original sources

Levels of di-(2-ethylhexyl)phthalate and total phthalate esters in milk, cream, butter and cheese.

Di-(2-ethylhexyl)phthalate (DEHP) and total phthalate ester plasticizer levels were determined in milk, cream, butter and cheese samples from a variety of sources from three European countries (UK, Norway and Spain). Samples of milk (from Norway) obtained at various stages during collection, transportation and packaging operations showed no apparent trends in phthalate contamination with total phthalate levels (expressed as DEHP equivalents) in the raw milk of between 0.12 and 0.28 mg/kg. On processing the DEHP was concentrated in the cream at levels up to 1.93 mg/kg, whereas low fat milk contained from < 0.01 to 0.07 mg/kg. Retail dairy products (from Spain) were contaminated with < 0.01-0.55 mg/kg DEHP with a maximum total phthalate level of 3.0 mg/kg in cream samples. UK pooled milk samples from doorstep delivery (obtained from different regions of the country) contained low levels of DEHP (< 0.01-0.09 mg/kg) and total phthalate (0.06-0.32 mg/kg). Retail UK samples of cheese, butter and other fatty products varied considerably in their levels of contamination, the highest being cheese samples containing 17 mg/kg of DEHP and 114 mg/kg total phthalate. However, the majority of samples contained 0.6-3.0 mg/kg DEHP and 4-20 mg/kg total phthalate. UK cream samples contained levels of 0.2-2.7 mg/kg DEHP and 1.8-19.0 mg/kg total phthalate. The level found in these products was too high to have resulted solely from milk by concentration in the fat phase and must therefore have arisen in other ways.

Animals↗

A review of the research requirements for Europe to support legislation in the area of food contact materials and articles.

A strong science base is required to underpin the planning and decision making process involved in determining future European Community legislation in the area of food contact materials and articles. The generation of this science base should be undertaken on a Europe-wide basis and needs to be coordinated to avoid duplication of effort and to secure agreement on the underlying science being used to determine future strategy. This review considers possible work that might be required in the future to support legislation on food contact materials and classifies it in terms of short-term problem-solving and longer-term strategic research.

Europe↗

Analytical quality assurance for the WHO GEMS/Food-EURO programme--results of 1993/94 laboratory proficiency testing.

As a means of assessing the performance of European laboratories who contribute analytical data on food contamination to the World Health Organization (WHO) Global Environmental Monitoring Scheme (GEMS), a series of five proficiency testing exercises were carried out during 1993 and 1994. In total 136 laboratories from 21 different countries took part in one or more of the exercises which covered the analysis of trace elements (lead, cadmium and mercury) in milk powder, pesticides (organochlorine, organophosphorus and pyrethroid) in spinach powder, nitrate in spinach powder, aflatoxins in nut-based animal feed and patulin in apple juices. The proficiency testing was carried out according to the ISO/IUPAC/AOAC INTERNATIONAL Harmonized Protocol and laboratories were awarded z-scores signifying their analytical capability based on their reported results for each of the respective exercises. Overall 60% of laboratories were satisfactory for accuracy for trace element analysis, 41% for pesticides, 43% for nitrate, 88% for aflatoxins and 53% for patulin. These results gave an overall poorer performance (68%) than the average for other similar schemes (79%), indicating the need for care in collating data for such programmes as GEMS and the need for remedial measures to assist in improving performance.

Aflatoxin B1↗

Indicators of intensive care in critically ill patients.

To define severity of illness objectively and to justify further the need for intensive care, we have analyzed measurable objective data points (indicators) in 226 consecutive critically ill Class IV patients. The indicators include: (1) Pao2 (Fio2, 1.0), (2) platelet count, (3) cardiac index, (4) BUN, 5) creatinine, (6) acute renal failure, (7) peritoneal or hemodialysis, (8) continuous infusion of antiarrhythmia therapy, (9) base deficit greater than 10mEq/liter, (10) state of consciousness, and (11) unexpected cardiac arrest. Most indicators were significantly worse in patients who ultimately died within one year than in patients who survived with a successful recovery. An indicator profile could be derived for each disease process category, since different indicators applied to different diseases. The indicators were not markedly affected by age. Standard discriminate analysis predicted a group of patients who would not survive and documented that acute renal failure was a primary predictor of death.

Acid-Base Imbalance↗

Clinical decision making in patients with congestive heart failure: the role of thoracic electrical bioimpedance.

Optimizing appropriate pharmacologic therapy in patients with congestive heart failure has been difficult due to a lack of easily obtainable hemodynamic information to guide the approach to the patient. Recently, thoracic electrical bioimpedance has allowed reliable outpatient determination of these hemodynamic variables, potentially allowing tailored adjustment of therapy in patients with cardiac dysfunction. Case studies are presented in which bioimpedance data were important contributing factors in optimizing patient management. Utilization of this new technology to individualize patient therapy should lead to improved outcomes and more efficient use of health care resources. (c)2000 by CHF, Inc.

Journal Article↗

Intraperitoneal chemotherapy: a prolonged infusion of 5-fluorouracil using a novel carrier solution.

A novel carrier solution, icodextrin 20 (7.5%) has allowed exploration of prolonged intraperitoneal (IP) infusion of the cytotoxic drug, 5-fluorouracil. Eighteen patients with intraperitoneal carcinomatosis were entered into a feasibility and pharmacokinetic study of prolonged regional (IP) chemotherapy.. Specialist nurses trained the patients to self-administer their own treatment via a permanent i.p. catheter. A twin bag delivery system was used to perform one exchange daily. It proved possible to deliver continuous (5 days per week) i.p. 5-fluorouracil at doses of 200 mg/m2 and 300 mg/m2 for up to 12 weeks. The toxicities seen were infective peritonitis, nausea and vomiting, lethargy and anorexia. This was a nurse-led study and the home-based therapy holds promise for patients with malignant peritoneal disease.

Adult↗

Biosynthesis of trichothecene mycotoxins in Fusarium culmorum cultures.

A high yielding production of the trichothecene mycotoxin 3-acetyldeoxynivalenol (3-AcDON) in cultures of Fusarium culmorum is described. By supplying [14C]acetate, 14C-labelled 3-AcDON suitable for further metabolic studies has been obtained. The pattern of labelling has been ascertained by using 13C-labelled acetate precursors, and is in line with established biosynthetic data. A second trichothecene produced in significant amounts by F. culmorum has been identified as 3 alpha, 15-diacetoxy-7 alpha, 8 alpha-dihydroxy-12, 13-epoxytrichothec-9-ene (7 alpha, 8 alpha-dihydroxycalonectrin).

Chemical Phenomena↗

Trichothecene mycotoxins from Fusarium culmorum cultures.

Chemical analysis of the culture filtrates of Fusarium culmorum CMI 14764 has demonstrated the presence of seven trichothecene mycotoxins. Major metabolites are 3-acetyldeoxynivalenol and 7 alpha, 8 alpha-dihydroxycalonectrin, with 3,15-diacetyldeoxynivalenol, deoxynivalenol, calonectrin, isotrichodermin and 12,13-epoxytrichothec-9-ene (EPT) as minor products. The occurrence of the rarely encountered unsubstituted trichothecene EPT is significant in that this compound may function as a common intermediate in the biosynthetic pathways to all natural trichothecenes. The structures of the known trichothecenes isolated from F. culmorum suggest a route in which EPT is sequentially oxygenated to the more complex deoxynivalenol derivatives.

Culture Media↗

Immunoaffinity column cleanup with liquid chromatography using post-column bromination for determination of aflatoxins in peanut butter, pistachio paste, fig paste, and paprika powder: collaborative study.

A collaborative study was conducted to evaluate the effectiveness of an immunoaffinity column cleanup liquid chromatography (LC) method for the determination of aflatoxin B1 and total aflatoxins at European regulatory limits. The test portion is extracted with methanol-water (8 + 2) for dried figs and paprika, and with methanol-water (8 + 2) plus hexane (or cyclohexane) for peanut butter and pistachios. The sample extract is filtered, diluted with phosphate buffer saline, and applied to an immunoaffinity column. The column is washed with water and the aflatoxins are eluted with methanol. Aflatoxins are quantitated by reversed-phase LC with post-column derivatization (PCD) involving bromination. PCD is achieved with either an electrochemical cell (Kobra cell) and addition of bromide to the mobile phase or pyridinium hydrobromide perbromide. Determination is by fluorescence. Peanut butter, pistachio paste, dried fig paste, and paprika powder samples, both naturally contaminated with aflatoxins and containing added aflatoxins, were sent to 16 collaborators in 16 European countries. Test portions of samples were spiked at levels of 2.4 and 9.6 ng/g for total aflatoxins which included 1.0 and 4.0 ng/g aflatoxin B1, respectively. Recoveries for total aflatoxins ranged from 71 to 92% with corresponding recoveries for aflatoxin B1 of 82 to 109%. Based on results for spiked samples (blind duplicates at 2 levels) as well as naturally contaminated samples (blind duplicates at 4 levels, including blank), the relative standard deviation for repeatability ranged from 4.6 to 23.3% for total aflatoxins and from 3.1 to 20.0% for aflatoxin B1. The relative standard deviation for reproducibility ranged from 14.1 to 34.2% for total aflatoxins, and from 9.1 to 32.2% for aflatoxin B1. The method showed acceptable within-laboratory and between-laboratory precision for all 4 matrixes, as evidenced by HORRAT values <1, at the low levels of determination for both total aflatoxins and aflatoxin B1.

Aflatoxin B1↗

Liquid chromatographic method with immunoaffinity column cleanup for determination of ochratoxin A in barley: collaborative study.

A collaborative study was conducted to evaluate a liquid chromatographic (LC) method with immunoaffinity column cleanup for determination of ochratoxin A. The method was tested at 3 concentration levels of ochratoxin A in barley, which represent possible future European regulatory limits. The test portion was extracted with acetonitrile-water by blending at high speed. The extract was filtered, diluted with phosphate-buffered saline (PBS), and applied to an ochratoxin A immunoaffinity column. The column was washed with water and the ochratoxin A eluted with methanol. The solvent was then evaporated and the residue redissolved in injection solvent. After injection of this solution onto reversed-phase LC column, ochratoxin A was measured by fluorescence detection. Eight samples of low level naturally contaminated barley and 2 samples of blank barley (ochratoxin A not found at the limit of detection of 0.2 microg/kg at the signal-to-noise ratio of 3 to 1) were sent, along with ampules of ochratoxin A, calibrant, and spiking solutions, to 15 laboratories in 13 different European countries. Test portions were spiked with ochratoxin A at levels of 4 ng/g, and recoveries ranged from 65 to 113%. Based on results for spiked samples (blind duplicates) and naturally contaminated samples (blind duplicates at 3 levels), the relative standard deviation for repeatability (RSDr) ranged from 4 to 24%, and the relative standard deviation for reproducibility (RSDR) ranged from 12 to 33%. The method showed acceptable within- and between-laboratory precision, as evidenced by HORRAT values, at the low level of determination for ochratoxin A in barley.

Calibration↗

Liquid chromatographic method for determination of patulin in clear and cloudy apple juices and apple puree: collaborative study.

A collaborative trial was conducted to validate the effectiveness of a liquid chromatographic (LC) procedure for determination of patulin in both clear and cloudy apple juices and apple puree. The test portion of clear apple juice was directly extracted with ethyl acetate; cloudy apple juice and apple puree were treated with pectinase enzyme before extraction. After back-extraction into sodium carbonate to remove interfering acidic compounds, the extract was dried and concentrated, and patulin was determined by LC with UV detection. Clear and cloudy apple juices, apple puree test samples naturally contaminated with patulin, and blank test samples for spiking with patulin were sent to 14 collaborators in 12 different European countries. Test portions of each of the 3 test sample types were spiked with patulin at 75 ng/g. Recoveries of patulin ranged from 80 to 92%. Based on the results for spiked test samples (blind pairs) and naturally contaminated test samples (blind pairs at 3 levels), the relative standard deviations for repeatability (RSDr) and reproducibility (RSDR) ranged from 8 to 35% and 11 to 36%, respectively. Although HORRAT values of <1.4 were obtained for all 3 matrixes at patulin levels ranging from 26 to 121 ng/g, better performance values (RSDr values 6-10% and RSDR values 11-25%) were obtained for clear and cloudy apple juice spiked above 50 ng/g, which is either the statutory limit or the advisory level for patulin contamination in apple juices in many countries.

Beverages↗

Immunoaffinity column cleanup with liquid chromatography for determination of aflatoxin M1 in liquid milk: collaborative study.

A collaborative study was conducted to evaluate the effectiveness of an immunoaffinity column cleanup liquid chromatographic method for determination of aflatoxin M1 in milk at proposed European regulatory limits. The test portion of liquid milk was centrifuged, filtered, and applied to an immunoaffinity column. The column was washed with water, and aflatoxin was eluted with pure acetonitrile. Aflatoxin M1 was separated by reversed-phase liquid chromatography (LC) with fluorescence detection. Frozen liquid milk samples both naturally contaminated with aflatoxin M1 and blank samples for spiking, were sent to 12 collaborators in 12 different European countries. Test portions of samples were spiked at 0.05 ng aflatoxin M1 per mL. After removal of 2 noncompliant sets of results, the mean recovery of aflatoxin M1 was 74%. Based on results for spiked samples (blind pairs at 1 level) and naturally contaminated samples (blind pairs at 3 levels) the relative standard deviation for repeatability (RSDr) ranged from 8 to 18%. The relative standard deviation for reproducibility (RSDR) ranged from 21 to 31%. The method showed acceptable within- and between-laboratory precision data for liquid milk, as evidenced by HORRAT values at the low level of aflatoxin M1 contamination.

Aflatoxin M1↗

Combined phenyl silane and immunoaffinity column cleanup with liquid chromatography for determination of ochratoxin A in roasted coffee: collaborative study.

A collaborative study was conducted to evaluate a liquid chromatography (LC) method for ochratoxin A using sequential phenyl silane and immunoaffinity column cleanup. The method was tested at 3 different levels of ochratoxin A in roasted coffee, which spanned the range of possible future European regulatory limits. The test portion was extracted with methanol and sodium bicarbonate by shaking for 30 min. The extract was filtered, centrifuged, and then cleaned up on a phenyl silane column before being eluted from the washed column with methanol-water. The eluate was diluted with phosphate-buffered saline (PBS) and applied to an ochratoxin A immunoaffinity column, which was washed with water. The ochratoxin A was eluted with methanol, the solvent was evaporated, and the residue was redissolved in injection solvent. After injection of this solution onto a reversed-phase LC apparatus, ochratoxin A was measured by fluorescence detection. Eight laboratory samples of low-level naturally contaminated roasted coffee and 2 laboratory samples of blank coffee (< 0.2 ng/g ochratoxin A at the signal-to-noise ratio of 3:1), along with ampules of ochratoxin A calibrant and spiking solutions, were sent to 15 laboratories in 13 different European countries. Test portions of the laboratory samples were spiked at levels of 4 ng/g ochratoxin A, and recoveries ranged from 65 to 97%. Based on results for spiked blank material (blind duplicates) and naturally contaminated material (blind duplicates at 3 levels), the relative standard deviation for repeatability (RSDr) ranged from 2 to 22% and the relative standard deviation for reproducibility (RSDR) ranged from 14 to 26%. The method showed acceptable within- and between-laboratory precision, as evidenced by HORRAT values, at the low level of determination for ochratoxin A in roasted coffee.

Calibration↗

Determination of aflatoxin B1 in baby food (infant formula) by immunoaffinity column cleanup liquid chromatography with postcolumn bromination: collaborative study.

A collaborative study was conducted to evaluate the effectiveness of an immunoaffinity column cleanup liquid chromatography (LC) method for determination of aflatoxin B, in a milk powder based infant formula at a possible future European regulatory limit (0.1 ng/g). The test portion was extracted with methanol-water (8 + 2 [v + v]), filtered, diluted with water, and applied to an immunoaffinity column. The column was washed with water to remove interfering compounds, and the purified aflatoxin B1 was eluted with methanol. The separation and determination of the aflatoxin B1 was performed by reversed-phase LC and detected by fluorescence after postcolumn derivatization (PCD) involving bromination. PCD was achieved with either pyridinum hydrobromide perbromide (PBPB) or an electrochemical (Kobra) cell by addition of bromide to the mobile phase. The baby food (infant formula) test samples, both spiked and naturally contaminated with aflatoxin B1, were sent to 14 laboratories in 13 different European countries. Test portions were spiked at levels of 0.1 and 0.2 ng/g for aflatoxin B1. Recoveries ranged from 101 to 92%. Based on results for spiked test samples (blind pairs at 2 levels) and naturally contaminated test samples (blind pairs at 3 levels), the relative standard deviation for repeatability (RSDr) ranged from 3.5 to 14%. The relative standard deviation for reproducibility (RSDR) ranged from 9 to 23%. Nine participants used PBPB derivatization, and

Aflatoxin B1↗

Determination of ochratoxin A in baby food by immunoaffinity column cleanup with liquid chromatography: interlaboratory study.

An interlaboratory study funded by the European Commission, Standards, Measurement and Testing Programme (4th Framework Programme) was performed to evaluate the effectiveness of an immunoaffinity column cleanup liquid chromatographic (LC) method for the determination of ochratoxin A in baby food at a possible future European regulatory limit (0.1 ng/g). The test portion is extracted in a blender with tert-butyl methyl ether (chosen to avoid use of chloroform but shown to give equivalent extraction efficiency) after addition of 0.5 mol/L phosphoric acid-2 mol/L sodium chloride solution. The extract is centrifuged and redissolved in a mixture of phosphate buffered saline solution and methanol. After removal of lypophilic substances with hexane, the extract is applied to an immunoaffinity column containing antibodies specific to ochratoxin A. The column is washed with water to remove the interfering compounds and the purified ochratoxin A is eluted with methanol. The separation and determination of ochratoxin A is performed by reversed-phase LC and detected by fluorescence after postcolumn derivatization (PCD) with ammonia. Test materials (baby food infant formulae), both spiked and naturally contaminated with ochratoxin A, were sent to 13 laboratories in 8 different European countries. Test portions were spiked at a level of 0.085 ng/g ochratoxin A. The average recovery for the spiked blank baby food was 108%. Based on results for spiked samples (blind pairs at 0.085 ng/g) as well as naturally contaminated samples (blind pairs at levels between 0.05 and 0.22 ng/g) the relative standard deviation for repeatability (RSDr) ranged from 18-36%. The relative standard deviation for reproducibility (RSDR) ranged from 29-63% and HORRAT values of between 0.4 and 0.9 were obtained.

Algorithms↗