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Biomedical subjects

J A Marlett

Publications and source records attributed to J A Marlett.

At least 19 recordsLinked to original sources
PubMed1992

Determination of fermentable carbohydrate from the upper gastrointestinal tract by using colectomized rats.

The primary aim of this study was to characterize the carbohydrate that would be supplied to the colon for fermentation under physiological conditions. Colectomized rats were fed fiber-free diets or diets containing 5% (wt/wt) gum arabic. Four (fucose, galactose, glucosamine, and galactosamine) of 11 analyzed sugars accounted for 77% of the total sugar in ileal excreta from colectomized rats fed fiber-free diets. The three sugars in gum arabic, rhamnose, arabinose, and galactose, accounted for 84% of the total sugars in gum arabic ileal excreta. Comparisons of the sugar compositions of the ileal excreta, the water-soluble fractions of the excreta, and three gel filtration fractions of the water-soluble material with those of the water-soluble fraction of rat mucosa, the acetone-soluble fraction of pancreas, and pancreatin suggested that the major source of endogenous carbohydrate is mucin. Gum arabic increased the daily excretion of the four mucin-derived sugars (fucose, galactose, glucosamine, and galactosamine) by the colectomized rats from 473 mumol per day to 634 mumol per day. We conclude that mucin is the major endogenous carbohydrate excreted from the upper gut and that gum arabic increases the amount of this endogenous carbohydrate.

Animals↗
PubMed1992

Content and composition of dietary fiber in 117 frequently consumed foods.

Twenty-three fruits, 33 vegetables, 41 grain products, 7 legumes, 4 nuts, and 9 miscellaneous foods were analyzed by an accurate chemical method to determine their dietary fiber content and composition. The mean (+/- standard deviation) dietary fiber content of fruits was 1.4 +/- 0.7 g/100 g (fresh weight); of vegetables, 2.0 +/- 0.8 g; of 32 refined grains (less than 5% fiber), 2.3 +/- 1.0 g; of legumes, 4.0 +/- 0.7 g; and of nuts, 6.4 +/- 2.1 g; the dietary fiber content of nine higher-fiber grains (greater than 5%) was variable. The soluble fiber fraction averaged 23% of the total fiber in refined grains, 3% in nuts, and 13% to 20% in the other food groups. Dietary fiber composition of every food group was heterogenous. Pectin, which was negligible in grains, constituted approximately 15% to 30% of the fiber in fruits, vegetables, legumes, and nuts. Hemicelluloses composed about half of the total fiber in grains, and approximately 25% to 35% of total fiber in other foods. Cellulose was one third or less of the total fiber in most foods, except for legumes, in which it was about one half. Values for total dietary fiber content generally agree with those reported previously. The soluble fiber fraction was lower than what has been reported because the distribution of total fiber between the soluble and insoluble fractions is determined by the method of analysis. The analyses used in this study demonstrated that the concentration of dietary fiber in many frequently consumed foods is 1% to 3%. The generally similar fiber concentrations of food within a group--fruits, vegetables, refined grains, and legumes--suggest that an average value for the fiber concentration in that group can be used to rank food intakes and histories into low, medium, or high dietary fiber contents.

Dietary Fiber↗
PubMed1991

Starch bioavailability in the upper gastrointestinal tract of colectomized rats.

Colectomized rats were used to compare the bioavailability of starch from canned peas, kidney beans, lima beans, corn, cooked rice and AIN-76A purified diet. Postoperative weight gains of colectomized and sham-operated rats were not different. Test meals of approximately 2 and approximately 3.3 g (dry weight) of each food containing chromic oxide (0.6 g/100 g) were administered to 4-6 rats by gastric intubation. Chromium recovery in ileal digesta 10 h after the meal ranged from 94 to 102%. Significant starch (11-15%) from peas, lima beans or kidney beans was recovered in the ileal digesta; 0.2-0.4% of starch from rice, corn or AIN-76A was in the ileal digesta. Pretreatment of kidney or lima beans with a heat-stable endo-alpha-amylase decreased the starch recovered in the ileal digesta to 2.7-4.3% of that fed; pretreatment with the amylase and pepsin had no further effect. Oligosaccharide extraction, the size of the test meal and the amount of starch did not affect starch bioavailability.

Animals↗
PubMed1990

Simultaneous determination of neutral and amino sugars in biological materials.

A method is described for the simultaneous analysis of nine neutral and three amino sugars. Mixtures of standard sugars and biological samples were acid hydrolyzed with a two step Saeman procedure, neutralized with BaCO3, reduced with sodium borohydride, acidified, evaporated and alditol acetates prepared. Baseline resolution was achieved on a glass-capillary SP-2340 column in ca. 52 min. Reproducibility, response factors and hydrolysis losses were determined. Quantitation was linear over the range of 10-20 micrograms/ml to 2000 micrograms/ml. Conditions were defined for the reproducible quantitation of muramic acid.

Amino Sugars↗
PubMed1990

Dose response to a dietary oat bran fraction in cholesterol-fed rats.

The two objectives of this research were to improve the cholesterol-fed rat as a model for evaluating the hypocholesterolemic potential of foods and to determine the relationship between serum and liver lipid levels in the cholesterol-fed rat and the ingestion of nine levels of a high fiber oat flour (HFOF) derived from oat bran. Ingestion of 0.2% cholic acid, sodium cholate or sodium taurocholate with 1% cholesterol (CH) significantly elevated serum and liver CH, liver triglycerides and liver weight compared to those values in control rats fed diets not containing CH and bile acids; 0.05 and 0.1% cholic acid with 1% CH were also effective. Ingestion of increasing amounts of HFOF, containing 0-10% dietary fiber, by rats made hypercholesterolemic with 1% CH and 0.1% cholic acid in the diet produced a significant inverse relationship between serum and liver cholesterol levels and HFOF intake; r = 0.48, p less than 0.0001 for serum CH and r = 0.55, p less than 0.0001 for liver CH. Because of the similarities in the responses of humans and of the cholesterol-fed rat to oat fiber ingestion, this dose-response relationship in the rat model suggests that larger intakes of soluble oat fiber sources may be accompanied by greater reduction in serum CH levels in humans.

Animals↗
PubMed1990

Neutral sugar composition and gravimetric yield of plant and bacterial fractions of feces.

Separating dietary fiber from other polysaccharides in digesta and feces is necessary to understand its mechanisms of action. A gravimetric method that separates fecal plant and bacterial matter based on size and density was evaluated and modified to determine the plant and bacterial mass of lyophilized whole and blended rat and human feces. Three screen mech combinations (150 and 75 microns, 150 and 35 microns, 35 microns) were used with rat feces. Filtration of a homogenized rat fecal slurry sequentially through 150- and 35-microns-mesh screens versus 150- and 75-microns-mesh screens decreased the gravimetric recovery of bacteria from congruent to 35 to congruent to 25% of fecal dry weight and increased the plant fraction weight. Neutral sugar composition, determined by gas chromatography of alditol acetates, and bacterial counts of the fractions suggested that the decreased yield of bacterial fraction represented removal of plant material and not a loss of bacteria. Rat excreta contained 29.5% (dry weight) total neutral sugar, 88% of which was recovered in the plant material. Human feces containing wheat bran, fractionated with the 150- and 35-microns-mesh screens, was 21% neutral sugar, congruent to 65% of which was in the plant fraction. The plant fractions had more xylose and arabinose and less glucose than the bacterial fractions. Processing samples in a Waring blender had no adverse effect on the rat or human fecal bacterial counts. The use of this gravimetric method in combination with the sugar analysis of the fractions provided a better measure of plant and bacteria than only gravimetric yield.

Animals↗
PubMed1989

Long-term nutritional status of an enterally nourished institutionalized population.

Growth and nitrogen nutriture were evaluated during a yearlong study of 11 profoundly retarded nonambulatory institutionalized youth who were fed by gastrostomy and received anticonvulsants. The effects of dietary fiber and vitamin D were assessed by determining plasma levels and balances of zinc, magnesium, calcium, and phosphorus in a subset of six patients. Increase in body weight was 3.4 +/- 2.4 kg (means + SD), in height, 5.9 +/- 3.9 cm during the year. N balance remained positive throughout the study. Zn and Ca balances suggested that needs for this population may be greater than or equal to 150% of the Recommended Dietary Allowance. Vitamin D supplementation had no effect. Soy polysaccharide fiber intakes of 18-24 g/d compared with 0 or 12-20 g fiber/d significantly improved N and P retentions. Although the determination of nutrient needs of a severely disabled population is complex, our results suggest N and energy but not Zn and Ca allowances for a healthy population may be satisfactory guidelines.

Adolescent↗
PubMed1989

Recovery of soluble dietary fiber is dependent on the method of analysis.

The effects of different methods on the distribution of total neutral sugars (TNS), uronic acids (UA), and beta-glucans (beta G) between the soluble (S) and insoluble (I) fractions of dietary fiber (DF) were determined for peas, kidney beans, oat bran, rice, and macaroni. Incorporation of a protease step into the Theander method "A" modestly increased, and addition of a pepsin digestion further increased the proportion of total fiber recovered in the S fraction. The effect of extraction method on the distribution of TNS, UA, and beta G between the S and I fractions varied with the food. The three methods measured the same total DF in a food and 1-3% starch in the I fraction of peas and kidney beans. Use of dimethyl sulfoxide to solubilize starch, or elevated temperature to extract S components, had no effect on the distribution of DF between S and I fractions of peas and macaroni. Incomplete protein hydrolysis did not always lower Klason lignin and excluding lignin from the fiber complex did not always substantially increase the S fraction.

Dietary Carbohydrates↗
PubMed1988

Dietary fiber intakes of nursing home residents and independent-living older adults.

Daily dietary fiber intakes were determined for two groups of older adults with significantly different bowel habits: nursing-home (NH) residents who habitually took laxatives and independent-living (IL) adults who took laxatives occasionally. Fiber intakes were calculated from neutral detergent fiber (NDF) and Southgate total dietary fiber values. IL subjects (n = 7) consumed on average 9.0 +/- 1.6 g NDF and 18.8 +/- 4.6 g total fiber daily. The NH menu provided a similar amount of NDF but more total fiber. NH residents (n = 6) consumed approximately 70-85% of the fiber served. When fiber intakes were expressed as energy, NH and IL subjects consumed similar amounts of NDF but IL subjects consumed less total fiber. Grain products were major fiber sources for both groups; IL subjects consumed more fiber from fruits. Comparisons of fiber intakes, bowel function, lifestyles, and medications suggest that dietary fiber is only part of the basis for inadequate large bowel function experienced by some elderly populations.

Activities of Daily Living↗
PubMed1988

Oat fiber: composition versus physiological function in rats.

The effect of processing on the ability of oat fiber to lower plasma and liver cholesterol concentrations in rats was studied. Male Sprague-Dawley rats were fed diets containing 6% dietary fiber as cellulose, oat bran, high fiber oat flour or one of four processed high fiber oat flours for 3 wk. All diets also contained 1.0% cholesterol and 0.2% cholic acid. At the conclusion plasma and liver concentrations of cholesterol and triglycerides were measured. All of the oat products significantly lowered plasma and liver cholesterol without depressing food intake or weight gain. As little as 4% dietary fiber in a processed oat flour significantly lowered cholesterol concentrations. Detailed fiber analysis of all of the oat fiber products revealed that processing increased the proportion of the total fiber that was soluble. The proportions recovered as total beta-glucans and total neutral sugars also increased, in part because the proportion recovered as Klason lignin decreased in all of the processed oat flours except the one prepared by a high pressure extrusion process.

Animals↗
PubMed1988

Processed oat hulls as potential dietary fiber sources in rats.

Processed oat hull products were evaluated as potential dietary fiber sources. Three levels, 5, 10 and 15%, of processed oat hulls, bleached oat hulls or oat hulls coated with starch, were added to purified diets and fed to groups of rats for 6 wk. Control diets consisted of 5, 10 or 15% alpha-cellulose or commercial nonpurified diet. None of the oat hull products at the three levels tested had any negative effect on rat growth. Fresh and dry fecal weights increased linearly as the concentration of dietary fiber increased and were highly correlated with fiber intake (r = 0.95). Apparent digestibility of neutral detergent fiber in all diets was low and apparent calcium absorption was not consistently affected by any diet. None of the oat hull test diets lowered plasma or hepatic cholesterol levels, a finding consistent with the failure to detect mixed-linkage beta-glucans in any of the processed oat hull products. Detailed analysis of the processed oat hull fibers also indicated that they were greater than 95% insoluble fiber and high in cellulose and xylans. Light-microscopy histology of kidney, spleen, pancreas, stomach, duodenum, ileum and colon was normal. The extent of hepatocellular destruction produced by the cholesterol (1%) and cholic acid (0.2%) added to the diet to induce hypocholesterolemia was independent of the kind and amount of dietary fiber.

Absorption↗
PubMed1988

Bone status in nonambulant, epileptic, institutionalized youth. Improvement with vitamin D therapy.

This study was conducted to determine if the adverse effects of anticonvulsant drug therapy and nonambulancy on bone status could be overcome with vitamin D therapy in severely handicapped individuals. Six male and five female gastrostomy fed, nonambulant, epileptic, profoundly mentally retarded individuals ranging in age from 7 to 17 years were given vitamin D therapy at a dosage of 4,000 IU/m2 body surface area/day for 6 months. Photon absorptiometry and biochemical indices of bone status were measured to follow the effects of therapy. Bone mineral content expressed as a percentage of normal improved by 11 percent (p less than 0.01), from 59.6 to 66.1 percent. Tartrate-resistant acid phosphatase, total alkaline phosphatase, and the bone isoenzyme activities declined 11 percent, 18 percent, and 11 percent respectively. These reductions were not statistically significant but they were consistent with the improvements observed by photon absorptiometry. The results of our study suggest that a conservative supplement of vitamin D will improve the bone status of severely disabled youths.

Adolescent↗
PubMed1987

Effect of wheat bran on bowel function and fecal calcium in older adults.

Seven healthy older volunteers participated in a 33-day study consisting of three sample collection periods, a 10-day control, and two 10-day experimental periods. Subjects consumed their usual self-selected diets throughout and a daily wheat bran supplement (30 g) during the two experimental periods. Food intake was recorded daily by subjects and accuracy and completeness checked daily by personal interview. Apparent calcium absorption decreased significantly from 22.1 +/- 5.6% (mean +/- SD) during the control to 8.6 +/- 5.2% during the second bran period. The wheat bran supplement significantly increased wet and dry stool weights but had no effect on stool moisture or defecation frequency. Gastrointestinal transit time of a dose of chromium decreased significantly, from 75 +/- 33 to 54 +/- 19 hr; of a dose of polyethylene glycol insignificantly, from 98 +/- 59 to 69 +/- 46 hr. Mean recovery of 21 doses of chromium of 98.7 +/- 5.0% verified that stool collection was complete. The results suggest that the ability of wheat bran to regulate bowel function in the apparently healthy older adult may be accompanied by increased fecal calcium losses similar to what has been reported for younger adults.

Aged↗
PubMed1987

Comparative laxation of psyllium with and without senna in an ambulatory constipated population.

Our short-term study used objective and subjective criteria to evaluate the ability of two laxative preparations to relieve constipation. Forty-two adults who were constipated, i.e., had less than or equal to 3 bowel movements during 1 wk of a single-blind placebo treatment, were randomized to receive psyllium (7.2 g/day) or psyllium plus senna (6.5 + 1.5 g/day). Both laxatives increased defecation frequency and wet and dry stool weights although the added effect of the senna was clearly evident. Only the psyllium with senna increased stool moisture. Two distinct responses to the psyllium plus senna were evident; the subpopulation of high responders (n = 7) was responsible for most of the increase in stool frequency and dry weight in this group, and laxation in the subpopulation of normal responders (n = 12) was similar to that observed in those receiving psyllium alone. Both laxatives provided a similarly high degree of subjective relief and improvement in stool consistency. When constipation was assessed objectively by stool frequency and weight, laxation was attained by 63% of the psyllium plus senna group and 48% of the psyllium group.

Adult↗
PubMed1986

A simple method to estimate neutral detergent fiber content of typical daily menus.

The purpose of this research was to develop a simple method to estimate daily intakes of the insoluble fraction of dietary fiber, that portion most effective in increasing stool weight and defecation frequency and decreasing gastrointestinal transit time. Neutral detergent fiber (NDF) contents of 53 foods were determined by analysis and used to calculate the NDF content of typical institutional menus; mean NDF content (n = 14 days) was 10.8 +/- 1.4 g/day. Average NDF content of one serving of fruits and vegetables was approximately 1 g, of the refined grain products, approximately 0.5 g. Estimating daily NDF content of the menus was simplified without a loss of accuracy by substituting the mean NDF content of one serving of refined grains, vegetables, and fruits for the actual values, and by eliminating foods present at less than 1/4 of a serving. Crude fiber was a poor predictor of the NDF in a menu.

Diet↗