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Biomedical subjects

J Gilbert

Publications and source records attributed to J Gilbert.

At least 343 records · Page 19Linked to original sources
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Intermittent-flow expiratory ventilation (IFEV): delivery technique and principles of action--a preliminary communication.

The ventilator support utilized in acute respiratory failure can exacerbate an underlying lung injury. Various ventilation techniques have been introduced to prevent such damage by limiting tidal volume and inflation pressure, ensuring uniform expansion of the lung, and stabilizing lung volume during expiration. Acceptance of such methods has been limited. Intermittent-flow expiratory ventilation (IFEV) is the latest development in limited-excursion pulmonary ventilation. The method involves the delivery of fresh gas to the respiratory tree during expiration, thereby flushing out the anatomic deadspace and ensuring that the gas initially delivered to the alveolus with the succeeding inspiration is able to participate in gas exchange. By eliminating end-tidal gas in the conducting air passages, series deadspace is functionally reduced, permitting lowering of tidal volume and airway pressures without a corresponding reduction in CO2 removal. This effect may benefit patients who have acute lung injury by permitting ventilator settings with lower tidal volumes and peak airway pressures. The technique of IFEV delivery, a successful clinical application, and possible ways to improve IFEV efficiency are discussed.

Adult↗
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Liquid chromatographic determination of aflatoxin levels in peanut butters using an immunoaffinity column cleanup method: international collaborative trial.

Thirteen laboratories in 7 different countries participated in a collaborative trial to evaluate the immunoaffinity column cleanup procedure with quantitation by fluorescence liquid chromatography (post-column derivatization) for the determination of aflatoxins in peanut butters. Participants were sent 10 randomly numbered samples of roasted peanut butter for analysis (5 pairs of undisclosed duplicates). Two of the pairs were "blank" peanut butters to which aflatoxin standards had been added; these "spiked" samples were used for recovery purposes. The other 3 pairs of samples were a nominal "blank" and 2 naturally contaminated peanut butters. A full statistical presentation of the results is given. Coefficients of variation (CVs) for the total aflatoxin determinations for mean levels of 4, 15, and 38 microns/kg were between 32 and 44% for the blank and 2 trial samples. Recovery levels for the 2 spiked samples were 51-67%, with aflatoxin B1 recovery of 60%. Relative standard deviations for method repeatability (RSDr) and reproductibility (RSDR) for the 3 trial samples were 15-26% and 33-45%, respectively.

Aflatoxins↗
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Determination of aflatoxin concentrations in peanut butter by enzyme-linked immunosorbent assay (ELISA): study of three commercial ELISA kits.

Sixteen United Kingdom analytical laboratories participated in an evaluation of 3 commercially available enzyme-linked immunosorbent assay (ELISA) kits for analysis of aflatoxin in peanut butter. Each laboratory was sent 3 sets of 10 randomly numbered samples of peanut butter. Each set consisted of 5 pairs of undisclosed duplicates. Four of the sets of duplicates were naturally contaminated butters with "target" aflatoxin values (estimated by liquid chromatography) between 8 and 81 micrograms/kg. The fifth pair was a blank peanut butter containing approximately 3 micrograms/kg of total aflatoxins. A statistical treatment of the results of the study is presented, together with discussion of the relative merits of the different kits.

Aflatoxins↗
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Metabolic conversions of trichothecene mycotoxins: biotransformation of 3-acetyldeoxynivalenol into fusarenon-X.

The trichothecene mycotoxin 3-acetyldeoxynivalenol was transformed by cultures of the diacetoxyscirpenol producer Fusarium sp. strain C37410-90 into four compounds, identified as deoxynivalenol, 15-acetyldeoxynivalenol, 3,15-diacetyldeoxynivalenol and fusarenon-X. The major transformations are the result of specific esterification and de-esterification processes, but the production of fusarenon-X involves in addition a novel 4 beta-hydroxylation of the trichothecene ring system itself.

Biotransformation↗
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Gas chromatographic-mass spectrometric determination of epoxidized soybean oil contamination of foods by migration from plastic packaging.

A method for the quantitative determination of epoxidized soybean oil (ESBO) in foods is described. The procedure involves addition of a diepoxidized fatty acid ester internal standard, followed by lipid extraction from the food and transmethylation under basic conditions. Without further cleanup, the methylated fatty acid epoxides are derivatized to form 1,3-dioxolanes, which are then determined by capillary gas chromatography-mass spectrometry with selected ion monitoring. A detection limit of 2.0 mg/kg of epoxidized soybean oil in foods and a relative standard deviation of 7% have been achieved routinely. The method has been applied successfully to the analysis of cheeses, sandwiches, cakes, and microwave-cooked meals which have been contaminated with ESBO by migration from PVC film.

Epoxy Compounds↗
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Gas chromatographic-mass spectrometric determination of adipate-based polymeric plasticizers in foods.

A method for the quantitative determination of adipate-based polymeric plasticizers in foods is described. The procedure involves extraction from the food and transmethylation of the polymeric plasticizer to form dimethyladipate (DMA). The derivative is cleaned up by size-exclusion chromatography and determined by capillary gas chromatography-mass spectrometry with selected ion monitoring. The use of a deuterated internal standard at the extraction stage enables quantitation by stable isotope dilution. A detection limit of 0.1 mg/kg of the polymeric plasticizer in foods and a relative standard deviation of 4% have been achieved routinely. The method has been applied successfully to the analysis of cheese, sandwiches, meat, biscuits, and cake that have been in contact with polymeric plasticized poly(vinyl chloride) films.

Adipates↗
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Gas chromatographic determination of monoethylene glycol and diethylene glycol in chocolate packaged in regenerated cellulose film.

A method for the quantitative determination of monoethylene glycol (MEG) and diethylene glycol (DEG) in chocolate is described. The procedure involves dissolving the chocolate in hot water, defatting with hexane, removing sugars by precipitation, and analyzing as trimethylsilyl (TMS) ether derivatives by capillary gas chromatography. The use of butan-1,4-diol as an internal standard corrects for recovery, which is between 50 and 60%, to give a relative standard deviation of 10-11% for the determination of both glycols at the level of 50 mg/kg. The presence of MEG and DEG in chocolate is confirmed by full scanning gas chromatography/mass spectrometry of the TMS derivatives.

Cacao↗
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Effect of razoxane on metastases from colorectal cancer.

At a median follow-up of 5 years, adjuvant razoxane (125 mg b.d.) given 5 days/week indefinitely following resection of colorectal cancer provided no benefit in terms of survival or recurrence for Dukes' A or B patients when compared to untreated controls. However in Dukes' C patients this treatment reduced the recurrence rate (P = 0.05) and possibly increased survival time (P = 0.08). Analysis now of the development of metastases in this trial which entered 272 patients over 7 years shows that in the Dukes' C group the incidence of liver metastases in the razoxane-treated patients is only about half that of the untreated patients (18 per cent versus 34 per cent) and that the time to first appearance of the liver metastases is twice as long in the razoxane-treated group as it is in the untreated group (80 weeks versus 40 weeks). It is concluded that the benefit of adjuvant razoxane observed in the Dukes' C patients is due to the antimetastatic activity of the drug in reducing and slowing down the development of hepatic secondaries.

Antineoplastic Combined Chemotherapy Protocols↗
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The mechanical properties of milled and cast titanium for ceramic veneering.

This study compared the mechanical properties of machine-milled pure titanium and cast titanium. The metals were cast or milled to the dimensions of a standard tensile bar pattern. Each group was treated under three different conditions: as-cast (or as-milled), standard heat, and extended heat. Tensile testing found no difference in the mechanical properties of as-cast and as-milled titanium. Heat treatment significantly increased the ultimate tensile strength and the yield strength of cast titanium but had no such effects on milled titanium. There was no significant difference between the two metals in the modulus of elasticity or the percentage of elongation under the three treatment conditions.

Alloys↗
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Marginal fit of machine-milled titanium and cast titanium single crowns.

Eighteen type IV dental stone dies were fabricated from a metal master die that replicated a tooth prepared to receive a metal ceramic crown. They were divided into three groups according to the type of crowns to be made: (a) machine-milled, spark-eroded titanium crowns (Procera); (b) cast titanium crowns; and (c) noble alloy crowns (as the control). The control specimens showed the smallest mean marginal openings at 25 microns and were significantly different from both the machine-milled crowns (54 microns) and the cast titanium crowns (60 microns). The two types of titanium crowns were not significantly different from each other.

Analysis of Variance↗
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Ways, but no means.

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Aged↗
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Prime movers.

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Community Health Nursing↗
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Beyond the screen.

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Humans↗
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Gas chromatographic/mass spectrometric determination of benzene in nonstick cookware and microwave susceptors and its migration into foods on cooking.

Benzene in poly(tetrafluoroethylene) (PTFE) coatings of nonstick cookware was determined by heating a small amount of coating in a sealed vial. Gas chromatography/mass spectrometry (GC/MS) was used to analyze the vial headspace for benzene. A small survey (26 samples) of retail nonstick cookware detected benzene ranging from 2 to 50 micrograms/dm2 in 7 samples. Nonstick frying pans with various polymer coatings were obtained directly from 1 manufacturer. Benzene (6-30 micrograms/dm2) was detected in a number of these samples and was attributed to the use of a phenylmethyl silicone ingredient that contained benzene at 360 mg/kg. To determine the possible transfer of benzene from these coatings during normal use, several foods (puddings, cakes, and roast potatoes) were prepared in previously unused cookware. The foods were analyzed by using static headspace GC/MS. Benzene was not detected in any of these foods at a limit of detection of 2 micrograms/kg. In related studies, the determination of benzene release from microwave susceptors was performed by heating the materials in a sealed system at 190 degrees C for 4 min. Benzene release above 1 microgram/dm2 was not detected in 24 samples of susceptors. However, 1 specially supplied sample of non-metallized susceptor released 10 micrograms/dm2 benzene when heated above normal anticipated temperatures of usage (to 220 degrees C). Foods such as french fries and pizza when cooked according to the manufacturer's instructions in susceptors contained no benzene with a limit of detection of 2 micrograms/kg. Even under abuse conditions of susceptors, the transfer of benzene to foods remained below this limit.

Benzene↗