Biomedical subjects

G S Allgood

Publications and source records attributed to G S Allgood.

11 recordsLinked to original sources

PubMed2001

Postmarketing surveillance of new food ingredients: results from the program with the fat replacer olestra.

Market introduction of savory snacks containing olestra offered an opportunity to evaluate the safety of olestra in a free-living population and thereby compare the outcome to the previously established safety profile determined in clinical trials in which subjects were required to eat predetermined amounts at prescribed intervals. Therefore, a multifaceted postmarketing surveillance program was designed to evaluate consumer experience and safety of olestra in the marketplace. Customer comments were solicited through toll-free telephone numbers. Collected data were evaluated by both internal and external medical experts. About 10% of toll-free telephone calls reported health effects, most of which were gastrointestinal (GI) in nature. Clinical studies were designed and conducted to determine potential GI effects under the range of consumption patterns reported by toll-free calls. Health effects reported were those found commonly in the general population and analyses of the data found no biological reason to conclude that serious or meaningful health effects were the result of olestra consumption.

Adult↗

PubMed2001

Randomized, double-blind, placebo-controlled, food allergy challenge to olestra snacks.

Following approval of the fat replacer olestra for use in preparing savory snacks, Procter & Gamble implemented a postmarketing surveillance program to monitor marketplace introduction. Three and one-half percent of all health effects reported by consumers to the surveillance toll-free number were allergy-type symptoms (e.g., rash, itching, edema, hives, dyspnea). Because of these reports, we investigated whether olestra or some component of olestra snacks was a likely allergen in some subset of the population. A single center, randomized, double-blind, placebo-controlled, within-subject crossover food challenge study was conducted to confirm or refute the allergenicity of olestra snacks. Of the 65 subjects who reported symptoms consistent with immediate hypersensitivity to olestra's postmarketing surveillance program, 14 men and women traveled to the Arkansas Children's Hospital Research Institute to participate in this study. Each subject underwent a standard skin prick test at the beginning of the study, to help determine what component, if any, of the olestra product was allergenic. Following the skin prick test, subjects ate in random order, olestra-containing potato chips and regular fat-containing potato chips. The dose of potato chips consumed at each challenge was at least the amount alleged to have caused the symptoms that prompted the consumer to phone the postmarketing surveillance toll-free number. No subject experienced an allergic reaction after consuming the olestra-containing chips. Nor did any subject elicit a positive response to olestra following the skin prick testing. Two subjects had positive reactions consistent with immediate hypersensitivity after consuming the regular-fat, placebo potato chips. The results of this study confirm that olestra is unlikely to have an allergenic potential.

Adult↗

PubMed1996

Genotoxicity and subchronic toxicity studies with heated olestra.

Olestra is a class of sucrose-fatty acid polyesters intended for use as a non-caloric replacement of edible oil. Genotoxicity and subchronic toxicity studies were conducted to determine whether olestra could form genotoxic or toxic breakdown products during simulated commercial use. Heated olestra was prepared for these studies by batch-frying potato slices in olestra at 177-185 degrees C for 25-32 hr over 5-7 days. Genotoxicity of this previously heated olestra was assessed in four standard in vitro assays: (1) Salmonella mutagenesis (Ames test); (2) forward mutagenesis of mouse lymphoma cells at the thymidine kinase locus; (3) unscheduled DNA synthesis in rat hepatocytes; and (4) clastogenicity in cultured Chinese hamster ovary cells. These tests were conducted with previously heated olestra at concentrations up to at least 5 mg/ml both in the absence of exogenous bioactivation and, for assays (1), (2) and (4) with added liver microsomal (S-9) activation. The Ames and mouse lymphoma assays were performed with olestra (10 mg/ml and 23 mg/litre, respectively) either alone or emulsified with the non-toxic, non-ionic surfactant Pluronics F68, both in the presence and absence of metabolic activation. To test for clastogenicity in vivo, rats were administered previously heated olestra by gavage at 5 g/kg per day for up to 5 days and bone marrow cells were examined for chromosomal aberrations. Heated olestra lacked genotoxic activity detectable by the aforementioned assays. Heated olestra was fed to Fischer 344 rats at up to 10% of the diet (w/w) for 91 days. Evaluation of survival, food consumption, feed efficiency, physical condition, body weight, organ weight, haematological and clinical chemistry parameters, and histomorphology revealed no adverse effects attributable to ingestion of heated olestra at exposure levels in excess of those anticipated for human consumption. It is concluded that olestra used as a deep-frying medium conveys no genotoxic or toxic hazard at anticipated levels of human consumption.

Animals↗

PubMed1995

The effect of olestra on breath gas production and faecal microbial counts.

OBJECTIVE: To assess the effect of olestra consumption on breath hydrogen (H2) and methane (CH4) production and faecal microbial counts in humans consuming moderate or high fibre diets. A secondary objective was to assess the effect of olestra consumption on health status. DESIGN: Thirty-six-day parallel, placebo-controlled, double-blind study with baseline low fibre period (3 g/meal, 8 days) and treatment period (28 days). Four treatment groups: moderate (7 g/meal) or high fibre (24 g/meal), with olestra (24 g) or placebo. SETTING: Queen Margaret College, Edinburgh, Scotland. SUBJECTS: Ninety-seven adult subjects (30 males and 67 females) from the hospital staff and student population participated in the study. Ninety-four subjects successfully completed the study. INTERVENTION: Breath H2 and CH4 production were measured and faecal specimens were obtained for faecal microbial viable counts and direct microscopic cell counts at the end of the baseline period and the end of the treatment period. Standard clinical blood and urine assays were performed. Subjects were questioned regarding adverse events. RESULTS: Olestra demonstrated no significant effect on breath H2 or CH4 production following either moderate or high fibre intake. A trend for lower breath H2 production in the high fibre olestra group was seen. No effect of olestra consumption on faecal microbial counts or health status was observed. CONCLUSION: In normal subjects 24 g/d of olestra for 36 days does not interfere with normal intestinal fermentation of dietary fibre and does not significantly alter gut microflora populations.

Adult↗

PubMed1994

Reproducibility of the breath hydrogen measurement after a low and high fibre meal.

OBJECTIVE: To assess the intra-subject variability of the breath hydrogen (H2) response to a low and a high fibre test meal. DESIGN: Six week trial, consisting of three phases: screening (1 weeks), baseline period (1 week) and high fibre period (4 weeks). SETTING: Western General Hospital, Edinburgh, Scotland. SUBJECTS: Sixteen subjects from the hospital staff and student population were screened for breath methane (CH4) production. Seven non-CH4 producers, four males and three females, were included in the trial. All completed the study successfully. INTERVENTION: Breath H2 and CH4 production were measured over a 12h period on duplicate test days after a low and high fibre meal. The high fibre meal was consumed for 4 weeks before the high fibre test days to allow for bacterial adaptation. The effect of the high fibre meal on stool output and whole gut transit time was furthermore assessed. RESULTS: Individual differences in breath H2 area-under-the-curve between duplicate test days ranged from 4% to 39% after the low fibre meal and from 4% to 37% after the high fibre meal. Considerable variation was found to be inherent in the breath collection method. In two subjects, breath CH4 was detected in response to the test meals. Stool output and whole gut transit time remained unchanged. CONCLUSION: Considerable differences were found between duplicate breath H2 responses to standard test meals. The variation inherent in the collection procedure emphasizes the need to collect breath samples at least in duplicate. The data presented here can be useful in future sample size calculations for similar studies.

Adult↗

PubMed1991

The effect of piroctone olamine on reproduction of male and female rats.

The purpose of this study was to determine the effect of piroctone olamine, an antidandruff active, on reproductive performance, fertility, parturition, and neonatal viability and growth. Piroctone olamine was administered orally by gavage to three groups of 35 male Sprague-Dawley rats each beginning 64 days prior to mating and continuing until euthanized and to three groups of 35 female Sprague-Dawley rats each beginning 14 days prior to mating and continuing until euthanized. Animals in the treated groups received piroctone olamine in a combination of 1.0% methylcellulose and polyethylene glycol 400 as a single daily dose at levels of 0, 10, 100, and 250 mg/kg/day, at a volume of 2.5 ml/kg. The control group received the vehicle only. Ten randomly selected females/group were mated and underwent a uterine examination on Gestation Day 13; the remaining females were allowed to deliver. Because earlier studies reported hematological effects, blood samples were collected from all parental animals during acclimation and prior to euthanasia for hematological and blood chemistry (Gestation Day 13 females) characterization. The parental animals were necropsied and tissues were grossly examined. Systemic effects induced by the test article were seen at the mid- and high-dose levels but only among the male rats. These effects were reduced body weight and decreased liver weights. Hematological findings representative of anemia occurred at the high-dose level, as did rales in several animals. Offspring growth was inhibited for the high-dose group as evidenced by significantly reduced mean weight values throughout lactation. The remaining parameters assessed, including mating ability and reproductive performance, were not affected by treatment at any dosage level tested. In summary, the no observable effect level of piroctone olamine with respect to systemic toxicity was considered to be 10 mg/kg/day. Neonatal growth was not affected at 100 mg/kg/day or less, and the no observable effect level with respect to reproductive parameters, including fertility, was 250 mg/kg/day.

Animals↗

PubMed1990

Allergic contact dermatitis from propyl gallate: dose response comparison using various application methods.

The antioxidant propyl gallate, in a deodorant product, caused an allergic contact dermatitis in 1 subject during developmental controlled use testing. Subsequent dose response elicitation studies with this subject revealed a differing threshold of sensitivity to propyl gallate dependent upon application method. Increasing the level of occlusion increased the elicitation response. Responsiveness from greatest to least was: occluded patch on the upper arm greater than semi-occluded axilla greater than open application on the antecubital fossa. The thresholds determined for propyl gallate (w/v in 25:75 ethanol:water) were: (a) 0.0025% for the upper arm occluded patch; (b) 0.0035% for the underarm without shaving; (c) 0.005% for the underarm with shaving; (d) 0.015% for the antecubital fossa. Occluded patch responsiveness to propyl gallate was monitored and remained unchanged throughout a 2-year period. These data are useful in understanding the relationship between occlusive allergic contact dermatitis patch testing and clinical contact dermatitis.

Administration, Cutaneous↗

PubMed1986

Effect of methyl viologen and oxygen concentration on thermophilic bacteria.

The level of superoxide dismutase, catalase, and peroxidase was determined in obligately thermophilic bacteria after growth either in the presence of methyl viologen (paraquat) or exposed to an increased atmospheric oxygen concentration. In general, the superoxide dismutase level in these organisms was not altered by paraquat addition and had a varied response to oxygenation. Incorporation of paraquat in the growth medium resulted in minimally three-fold higher levels of catalase. The peroxidase level varied as a response to oxygen stress whereas cellular catalase levels were generally higher.

Bacteria↗

PubMed1986

Characterization of a manganese-containing catalase from the obligate thermophile Thermoleophilum album.

A manganese-containing catalase has been characterized from Thermoleophilum album NM, a gram-negative aerobic bacterium obligate for thermophily and n-alkane substrates. The level of catalase in cells was increased about ninefold by growth in the presence of paraquat (2.5 microM), a superoxide-generating toxicant. Superoxide dismutase levels were unaffected by this compound. The enzyme was purified from cultures grown in the presence of paraquat to greater than 95% homogeneity and had an Mr of 141,000. The enzyme was composed of four subunits, and each had an Mr of 34,000. There were 1.4 +/- 0.4 atoms of manganese present per subunit. The catalase had a Km for hydrogen peroxide of 15 mM and a Vmax of 11 mM/mg. Peroxidase activity, as measured with p-phenylenediamine, copurified with the catalase. Inhibitors of heme-catalase were weak inhibitors of the T. album enzyme. The optimum pH for catalase activity was 8 to 9. The enzyme was stable from pH 6.5 to 11 and retained activity at assay temperatures from 25 to 80 degrees C. The catalase was stable for 24 h of incubation at 60 degrees C.

Catalase↗

PubMed1985

Paraquat toxicity and effect of hydrogen peroxide on thermophilic bacteria.

Paraquat (PQ++) increased cyanide-resistant univalent respiration in cell suspensions of five strains of obligately thermophilic bacteria. PQ++ was reduced by an NADH: or NADPH:paraquat diaphorase and selectivity for NADH, NADPH, or both electron donors varied among the thermophiles. Superoxide anion production that was dependent on the presence of PQ++ was shown by following the superoxide dismutase-inhibitable reduction of cytochrome c. In addition, the PQ++-dependent formation of hydrogen peroxide from superoxide anion was evident in two of the thermophilic strains. Catalase synthesis was induced by adding hydrogen peroxide to the growth medium of the thermophiles. The induction of catalase to eliminate hydrogen peroxide appears to be an important response of these thermophilic bacteria to oxygen toxicity.

Catalase↗

PubMed1985

Oxygen defense systems in obligately thermophilic bacteria.

Ten strains of Gram-negative, aerobic, obligately thermophilic bacteria were examined for their response to oxygen toxicity by comparing static with shaken cultures. All of the organisms tested had measurable levels of superoxide dismutase, catalase, and peroxidase. Aeration generally did not result in an increased level of superoxide dismutase in any of the thermophiles. Aeration of organisms obligate for n-alkane substrate caused an increase in cellular peroxidase levels and a corresponding decrease in catalase. The thermophiles that grew on either n-alkanes or complex media did not grow on the hydrocarbon in aerated culture but on a complex medium, aeration effected an increased level of catalase. With the exception of a pink-pigmented thermophile which, when aerated, did not have an increased level of the three oxygen defense enzymes, most of the thermophiles surveyed had an increased level of catalase or peroxidase when exposed to increased oxygen tension. The activity of the enzymes was determined at temperatures from 25 to 65 degrees C and the former temperature was satisfactory for these experiments.

Alkanes↗