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Biomedical subjects

C J Lewis

Publications and source records attributed to C J Lewis.

At least 55 records · Page 3Linked to original sources
PubMed1992

Nutrient intakes and body weights of persons consuming high and moderate levels of added sugars.

We classified a nationally representative sample of persons aged 4 years and older as high or moderate consumers of added sugars (ie, sugars added to foods by processors or consumers). Intake of added sugars was determined on the basis of grams consumed per kilogram of body weight (g/kg) and on the basis of percent of dietary energy from added sugars (% kcal). Regardless of the intake measure used, high consumers of added sugars had a significantly lower percentage of dietary energy from fat than did moderate consumers of added sugars. Persons defined by the % kcal measure as high consumers of added sugars took in lower percentages of the Recommended Dietary Allowances (RDAs) for 11 vitamins and minerals; these high consumers had body weights similar to those of their moderate counterparts. Persons defined as high consumers by the g/kg measure consumed greater percentages of the RDAs than did their moderate counterparts; these high consumers more frequently selected foods from categories likely to contain sugar-rich foods but weighed significantly less than did moderate consumers. Thus, different approaches to defining intake of added sugars revealed two patterns of high consumption of added sugars with different levels of nutritional risk. Conditions of overweight were not associated with high intake of added sugars. Educational efforts, therefore, should focus on those consumers who tend to substitute foods rich in added sugars for more nutritionally desirable foods.

Adolescent↗
PubMed1992

Focus group sessions on formats of nutrition labels.

Four consumer focus group sessions, with a total of 40 participants, were conducted to gather information on the utility and appropriateness of selected components of nutrition label formats. The formats reviewed were bar graphs, pie charts, numeric listings, and adjectival descriptors such as high and low. Participants were asked to compare food labels using various format types and to discuss the utility and interpretability of the formats. The outcomes suggested that these consumers did not find pie charts useful. They considered bar graphs confusing or unnecessary when numeric values were provided. Participants expressed concern that adjectival descriptors could be misleading. The numeric listing format they considered the most useful consisted of two columns of numbers: one listing the amounts of food components present in a serving of the food, and a second listing either the percentage of the label reference value (eg, the US Recommended Daily Allowance) or the quantity established as the label reference value. Participants repeatedly stressed their interest in a simple label. The results form one component of the Food and Drug Administration's efforts to evaluate nutrition label formats and will be used in conjunction with ongoing experimental and quantitative research studies.

Adult↗
PubMed1990

Relationship between age and serum vitamin A in children aged 4-11 y.

The association between age and serum vitamin A concentrations in children was examined by using total serum vitamin A values from the second National Health and Nutrition Examination Survey (NHANES II) and serum retinol values for Mexican Americans from the Hispanic HANES. Analyses included multivariate strategies to identify confounders of serum vitamin A. After the effect of the use of vitamin-mineral supplements on total serum vitamin A values was controlled for, the data indicated that younger children (aged 4-5 y) have lower serum vitamin A concentrations than do older children (aged 9-11 y) regardless of whether the measure was total serum vitamin A or serum retinol. This relationship was systematic across the distribution of values and suggested that the difference may be due to normal physiological events. A different interpretive criterion may be needed for younger and older children when serum vitamin A is used to indicate vitamin A status.

Aging↗
PubMed1989

CPD.

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Education, Continuing↗
PubMed1989

Examination of specific nutrition/health behaviors using a social cognitive model.

Nutrition intervention programs are not always successful. In some cases, an insufficient understanding of the interrelationships among factors influencing health behaviors may be responsible for the failures. This study used social cognitive theory, a framework for studying behaviors, to structure the relationships between measurable factors important to the frequency of health-oriented food consumption. We developed a model that incorporated factors for social environment, reinforcement, commitment, behavior modeling, knowledge, and attitude relative to the frequency of consumption of four beverages (whole milk, low-fat/skin milk, regular soda, and diet soda). Four-hundred fifty-seven middle-aged adults (mean age, 47 years; 58% female) and 709 college students (mean age, 21 years; 50% female) responded to a written questionnaire designed as a self-report on frequency of consumption and measures for 10 social cognitive variables. For all four beverages, the model explained 35% or more of the variance in frequency of consumption, thus confirming its predictive power. We used the statistical approach known as path analysis to examine the relationships within the model. The analysis demonstrated that factors influencing the consumption varied between the two age groups (e.g., nutrition knowledge was related to attitude in adult soda-drinking models but not in student soda-drinking models) and between forms of the beverages (e.g., for student models, nutrition knowledge was related to taste enjoyment for low-fat/skim milk but not for whole milk).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

The pharmacokinetics and metabolism of idazoxan in the rat.

1. [2'-14C]Idazoxan was rapidly and completely absorbed after its oral administration to rats. 2. After administration of either [2'-14C] or [6,7-3H]idazoxan, radioactivity was taken up by a wide range of tissues and became localized, especially in the organs of metabolism and excretion. Quantitative distribution patterns were route-dependent such that oral dosing resulted in lower radioactivity concentrations in all tissues apart from liver. 3. Clearance of idazoxan (94-144 ml/min per kg) was due mostly to metabolism and was independent of dose. Oral bioavailability in male rats at low oral doses of idazoxan (10 mg/kg) was about 1%, but increased with increasing dose to 23% at 100 mg/kg. Oral bioavailability in female rats was considerably higher than in male rats, at all doses studied. Brain idazoxan levels were in equilibrium with those in plasma, but ten-fold higher. 4. Elimination of radioactivity after administration of 14C-idazoxan was via the urine and the faeces (about 75% and 20% of dose respectively) and occurred essentially in the 24 h period immediately after dosing. By 96 h after dosing, elimination was virtually complete, with less than 0.5% dose remaining in the carcasses. 5. Biotransformation was by hydroxylation at positions 6 and 7 to form phenolic metabolites, which were excreted as glucuronide and sulphate metabolites in urine, but unconjugated in faeces. Other minor metabolic routes were 5-hydroxylation or oxidative degradation of the imidazoline ring, but these pathways were of quantitatively minor importance in the rat.

Adrenergic alpha-Antagonists↗
PubMed1988

Serving size issues in estimating dietary exposure to food substances.

The intake of cola beverages from two national surveys (NFCS 1977-78 and NHANES II) was used to examine certain assumptions important to a mathematical model employed to estimate dietary exposure to substances in food. The assumptions center on the relationship between frequency of consumption and serving size and on the constancy of serving size within age groups. Results showed the frequency of cola consumption was associated with 55% to 83% of the variability in cola intake and that mean cola serving size was not linearly related to frequency of consumption. However, while upper-level (90th + percentile) cola consumers consumed more frequently, they also had larger than average serving sizes. Therefore, because the model incorporates a standard serving size, it significantly underestimated (p less than .01) intake for the two groups of upper-level consumers examined. Furthermore, comparisons for cola serving sizes reported in the surveys showed differences by sex as well as systematic differences between the surveys in that the average difference between age and sex groups within each survey was similar, but NFCS 1977-78 had a larger average size for each group than did NHANES II. Attention should be given to the nature of the food consumption databases used for estimating dietary exposure because systematic bias may cause considerable differences in estimation.

Adolescent↗
PubMed1985

Assessment of an in situ rat intestine preparation with perfused vascular bed for studying the absorption and first-pass metabolism of drugs.

The perfused in situ rat jejunum preparation originally described by Hanson and Parsons (1976) was adapted for use in absorption and metabolism studies with drugs. The preparation allows simultaneous perfusion of the gut lumen and associated vasculature and is viable for one hour. The viability of the preparation was assessed, and the application of the method is illustrated by experiments with the opiate analgesic, buprenorphine.

Animals↗
PubMed1984

Measurement of total and specific IgE levels in the management of a family exhibiting a high incidence of keratoconus.

A prospective survey of a family, some of whose members were suffering from keratoconus, has been assisted by estimating serum levels of total and specific immunoglobulin E. In this family of twelve there were initially 2 keratoconus sufferers identifiable clinically, and they both had raised serum levels of total and specific IgE. Of three other younger siblings with high levels of IgE 2 have become, over the course of the study period, patients requiring regular review due to established early keratoconus. The third, as yet, has no clinical evidence of altered corneal stroma. We consider, therefore, estimation of total and specific serum immunoglobulin E to be an objective test with the potential for indicating high risk patients within selected groups. The patients thus identified may have established keratoconus or may progress to develop the condition.

Adolescent↗
PubMed1982

Immunoglobulin patterns in keratoconus with particular reference to total and specific IgE levels.

A selection of sufferers from keratoconus and random controls were assessed in order to substantiate claims that there existed a significant incidence of patients with both keratoconus and a raised serum level of immunoglobulin E. The results appeared to confirm a high incidence of raised total serum IgE levels in patients with keratoconus and also indicated that the additional measurement of serum specific IgE was more sensitive than total IgE. In fact 59% of the patients with keratoconus in our study were identified as having significantly raised level of specific immunoglobulin E, and 52% were identifiable by measuring total immunoglobulin E. This compares favourably with a previous incidence in a keratoconus population of 47% with raised total immunoglobulin E. Our study avoids clinical estimation of known associated systemic manifestations of atopic disease, thereby reaffirming the correlation between raised serum levels of IgE and keratoconus as objectively as possible. This identification pattern may be useful in reviewing high-risk groups and aid in the earlier detection of the condition.

Female↗
PubMed1982

In vivo modulation of human lymphocyte Fc gamma-receptors in response to oral antigen (cows' milk) challenge.

Following consumption of 1.2 litres of cows' milk by normal human adults there was a rapid fall in the proportion of peripheral blood lymphocytes bearing receptors for the reacted Fc of IgG (Fc gamma-receptors). This phenomenon was transient and apparently confined to the lymphocyte Fc gamma-receptor+ve subpopulation. Similar observations were made in rats but only in those animals pre-exposed to cows' milk suggesting that an immunological mechanism is involved. In man it was found that Fc gamma-receptors could only be re-expressed following incubation of post-milk lymphocytes in normal human serum. It is proposed that rapid in vivo modulation of lymphocyte Fc gamma-receptors occurs following oral antigen (cows' milk) challenge probably mediated by soluble food antigen-antibody complexes. The subsequent recovery of these receptors in vivo and in vitro may be due to the binding of 'fluid-phase' Fc gamma-receptors found in normal human serum.

Adult↗
PubMed1981

Biotransformation of tolmesoxide in animals and man.

1. The excretion and metabolism of tolmesoxide ((4,5-dimethoxy-2-methylphenyl)-methylsulphoxide) has been studied in rat, dog and man. In all species, absorption of oral doses of [14C]tolmesoxide was virtually complete and 78--99% of the 14C was excreted in the urine. 2. In bile-duct cannulated rats, excretion in bile and urine was 49% and 53% dose respectively. Metabolites of tolmesoxide in bile undergo enterohepatic circulation with final elimination by the kidneys. 3. Quantification and identification of metabolites in urine (0-24 h) were obtained by two-dimensional t.l.c. Tolmesoxide was extensively metabolized in all animal species. 4. The major routes of metabolism in rat, dog and man were oxidation to sulphones and O-demethylation followed by sulphate or glucuronide conjugation. Little or none of the urinary 14C was present as sulphide derivatives.

Adult↗
PubMed1980

Metabolism of ethynodiol diacetate in the rhesus monkey before and after administration of rifampicin.

1. On administration of a single oral dose of [4-(14)C]ethynodiol diacetate (0.15 mg/kg) to rhesus monkey, plasma concn. of total 14C peaked after about 4 h. About 60% of the plasma radioactivity was present as glucuronide conjugates and no unchanged drug was detected. 2. Some 67 +/- 6% (mean +/- S.D.) of the dose of 14C was excreted in 4 days, 50 +/- 6% in urine and 18 +/- 2% in faeces. Most of the urinary excretion occurred within 24 h of dosage. 3. Glucuronide conjugates accounted for 60% of the urinary 14C, and 46% of the faecal 14C was free steroids. 4. Norethisterone and its tetrahydro metabolites were identified in the free, glucuronide and sulphate fractions of plasma and urine. Keto-4,5-dihydronorethisterones and trihydroxy metabolites were identified in the conjugated fractions of urine, and a complex mixture of polar metabolites was detected in faeces. 5. Rifampicin treatment (7.5 mg/kg/day, orally) for 8 days decreased the half-life of total 14C in plasma following a single oral dose of 4-[14C]ethynodiol diacetate (0.15 mg/kg) from 44 +/- to 24 +/- 2 h. 6. Faecal elimination of total 14C was significantly increased to 29 +/- 5% of the dose following rifampicin treatment, but urinary excretion was unchanged. 7. Rifampicin treatment increased the amount of polar metabolites and decreased the amount of norethisterone in the free and conjugated fractions of plasma and urine. The amounts of sulphate and non-hydrolysed conjugates in faeces were increased after rifampicin treatment.

Animals↗