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Biomedical subjects

D J Jenkins

Publications and source records attributed to D J Jenkins.

At least 163 records · Page 9Linked to original sources
PubMed1987

Wheat fiber and laxation: dose response and equilibration time.

We studied the dose response to soft white winter wheat fiber on fecal output in a group of healthy volunteers whose breakfasts consisted of wheat fiber cereals in amounts that provided 0.3 g, 5.6 g, 9.5 g, 11.2 g, 19.0 g, and 28.4 g dietary fiber per day for 14 days; no other aspects of their diet were altered. A linear dose response was observed between the six levels of fiber intake (r = 0.983, p less than 0.01) with a 1-g increase in wheat fiber, producing a mean 2.7-g increase in fecal weight. This increase was independent of the initial daily fecal weight of the volunteer (mean 117 +/- 64 g/day, range 5-297 g/day, n = 73). The maximum increase in fecal output due to cereal fiber was reached after the first week on the supplement. These data support the use of graded amounts of cereal fiber in the management of constipation.

Adult↗
PubMed1987

Digestibility of carbohydrate foods in an ileostomate: relationship to dietary fiber, in vitro digestibility, and glycemic response.

The aim of this study was to assess differences between starchy foods in the amount of carbohydrate which escapes small intestinal absorption. One ileostomate volunteer tested in metabolic feeding trials a total of 20 starchy foods (nine of which were repeated on two to seven occasions, mean 3.5 +/- 1.7). This ileostomate volunteer exhibited macronutrient and fiber losses that were within 97.3 +/- 6.6% of the mean, for a range of foods eaten by three other ileostomates and was therefore believed to be representative. Measurement of available carbohydrate in ileal effluent demonstrated a wide range of recoveries from 2.7 to 18% from different starchy foods. The available carbohydrate losses related to the fiber content (r = 0.885, p less than 0.001), in vitro digestibility of the food (r = -0.867, p less than 0.01), and their glycemic responses (r = -0.611, p less than 0.05). Our data support the concept that available carbohydrate losses to the colon may be greater in many foods than the carbohydrate entering the colon as dietary fiber. The food factors responsible are diverse and the possible metabolic consequences of carbohydrate malabsorption may be broad.

Blood Glucose↗
PubMed1987

Effect of modifying the rate of digestion of a food on the blood glucose, amino acid, and endocrine responses in patients with cirrhosis.

To see whether foods with slower rates of digestion may benefit the metabolic abnormalities seen in cirrhosis, the same food, processed in two different ways, was fed to seven patients with cirrhosis. The breakfast of lentils processed by prolonged heating, to produce more rapid in vitro digestion, resulted in a significantly higher incremental rise in large neutral amino acid levels at 60 min (p less than 0.02) and a tendency for a more rapid rise in total amino acid concentrations by comparison with conventionally cooked lentils with slower in vitro digestion rates. After more rapidly digested lentils, incremental levels of branched-chain amino acids were also higher at 60 min (67 +/- 9, p less than 0.001) despite a greater overall insulin response. Comparable incremental amino acid areas after both meals suggested that the total amount of amino acids absorbed was not influenced by processing. Greater blood glucose, insulin, and gastric inhibitory polypeptide responses were seen after the more processed meal with no significant differences in pancreatic glucagon, entroglucagon, or neurotensin levels. Processing a food to alter the rate of digestion may therefore be used to manipulate amino acid, glucose, and endocrine responses in cirrhosis.

Aged↗
PubMed1987

Effect of canning on the blood glucose response to beans in patients with type 2 diabetes.

Cooked dried legumes have been shown to stimulate low blood glucose responses, and their consumption by individuals with diabetes has been encouraged. However, canned beans are more convenient to use than dried beans. Since the glycaemic effects of canned beans have not been determined, we fed 50 g carbohydrate portions of five varieties of beans, both cooked dried and canned, to groups of diabetic patients and calculated their glycaemic indices (GI). All canned and dried beans tested had significantly lower GIs than that of white bread, which was ascribed a GI of 100. The mean GI of the five types of canned beans, 71 +/- 4, was less than that of bread, 100 (P less than 0.001), and greater than that of the same five varieties of cooked dried beans, 47 +/- 5 (P less than 0.001). It is concluded that the glycaemic effect of dried legumes is increased by the canning process. Nevertheless, canned beans give lower blood glucose responses than bread and may be of use in low glycaemic index diets.

Aged↗
PubMed1986

The use of the glycemic index in predicting the blood glucose response to mixed meals.

There has been much interest in the use of the glycemic index (GI). A recent study reporting plasma glucose responses to mixed meals containing fat and protein concluded that the results were totally disparate from what would have been expected from published GI values of the foods fed. However, this conclusion was based upon an inappropriate assessment of the data using absolute rather than incremental blood glucose response areas. The present report demonstrates how data may be analyzed to make use of the GI values of individual foods to predict the GI of mixed meals (r = 0.987; p less than 0.02). It is concluded that the GI concept applies well to mixed meals containing fat and protein.

Blood Glucose↗
PubMed1986

Low glycemic response to traditionally processed wheat and rye products: bulgur and pumpernickel bread.

To look at the effect of processing wheat and rye on blood glucose responses with special reference to bulgur and pumpernickel bread, groups of 9-12 Noninsulin-dependent (NIDDM) and 5-6 Insulin-dependent diabetic volunteers (IDDM) were fed test meals containing 50 g carbohydrate portions of four wheat and three rye products. Glycemic indices for IDDM and NIDDM combined, calculated as the incremental area under the blood glucose response curve, where white bread = 100, demonstrated values of 96 +/- 5 for wholemeal wheat bread, 89 +/- 6 for wholemeal rye bread, 78 +/- 3 for pumpernickel bread, 65 +/- 4 for bulgur, 63 +/- 6 for whole wheat kernels and 48 +/- 5 for whole rye kernels. Results for IDDM and NIDDM were similar (r = 0.96, p less than 0.01). It is concluded that traditional processing of cereals, such as parboiling (bulgur) or the use of wholegrains in bread (pumpernickel) may result in the low GI value associated with the unmilled cereal. Cereal foods processed in these ways may form a useful part of the diet where a reduction in postprandial glycemia is required.

Aged↗
PubMed1986

Specificity of scolex and oncosphere antigens for the serological diagnosis of taeniid cestode infections in dogs.

Groups of dogs raised free of helminths were monospecifically infected with the common nematodes Toxocara canis, Ancylostoma caninum and Trichuris vulpis. Serums from these dogs, and a group of dogs of unknown history but infected with Dirofilaria immitis and Dipylidium caninum, had levels of antibody to their homologous nematode antigens readily detectable by ELISA. No cross-reactions were apparent when these serums were tested by ELISA using oncosphere antigens of Taenia hydatigena, T. pisiformis and T. ovis, scolex excretory/secretory antigens of T. hydatigena, T. pisiformis and Echinococcus granulosus or protoscolex antigen of E. granulosus.

Ancylostoma↗
PubMed1986

Specific antibody responses in dogs experimentally infected with Echinococcus granulosus.

Six dogs reared helminth-free were divided into 2 groups. Four dogs were infected per os with 200,000 protoscoleces each of Echinococcus granulosus and 2 were kept as uninfected controls. All the dogs were kept together until 32 days after infection, when 1 infected dog was killed, its intestine removed and the contents examined to confirm that the infection with E. granulosus had been successful. The remaining 3 infected dogs were transferred to high security housing and their feces inspected daily to establish the time infections became patent. The infected and control dogs were bled every 5 days for 75 days from the time of infection and the sera were stored at -70 degrees C. Sera were tested by the enzyme-linked immunosorbent assay (ELISA) for antibodies to E. granulosus scolex excretory/secretory (ES) antigen, protoscolex antigen and oncosphere antigen. Antibodies to scolex ES antigen and protoscolex antigen were detected in the sera of infected dogs within 2 weeks of infection. Antibody titers rose rapidly and remained at a high level until the dogs were killed 75 days after infection. Antibodies in these sera did not cross react with antigens prepared from Taenia ovis, T. hydatigena, T. pisiformis, Ancylostoma caninum, Trichuris vulpis and Toxocara canis.

Animals↗
PubMed1986

Ileal loss of available carbohydrate in man: comparison of a breath hydrogen method with direct measurement using a human ileostomy model.

The breath hydrogen technique has suggested that a considerable amount of available plus unavailable carbohydrate enters the large intestine after the consumption of starchy foods (white bread 11%, wholemeal bread 8%, and red lentils 18%). Direct measurement of the available carbohydrate in ileal effluent after the consumption of test meals by three individuals with ileostomies gave values similar to those determined by the breath hydrogen technique (white bread 10%, wholemeal bread 8%, and red lentils 22%). These studies confirm that considerable amounts of "available carbohydrate" may be lost to the small intestine and physiologically must be considered as dietary fiber. The implications of this with respect to metabolism and colonic disease remain to be investigated.

Adult↗
PubMed1986

Fiber and starchy foods: gut function and implications in disease.

Increased intake of fiber and starchy foods has been recommended in the treatment or prevention of a range of diseases including dumping syndrome, hyperlipidemia, gallstones, diabetes, Crohn's disease, constipation, irritable bowel, diverticular disease, and colonic cancer. The nature and physiological effects of fiber are diverse. However in general, insoluble fibers increase fecal bulk and decrease transit time. On the other hand, soluble fibers have metabolic effects secondary to reducing the rate of small intestinal absorption. In the colon, along with undigested starch, they are largely fermented yielding short-chain fatty acids which may have further metabolic effects. At present although much further work is required, the clinical management of hyperlipidemia, diabetes, constipation, and diverticular disease have already been significantly influenced as a result of the ideas and experimental evidence generated by the fiber hypothesis.

Colon↗
PubMed1986

Cancer risk: possible protective role of high carbohydrate high fiber diets.

Epidemiological data from different populations have suggested positive relationships between the incidence of colon cancer and meat and fat intake and a negative relationship with dietary fiber consumption. Within population comparisons have been less clearcut. Current theories on colonic carcinogenesis in man involve increased concentrations of bile acids and their metabolites, alterations in colonic pH, low Ca++, raised NH3 and long chain fatty acid levels, and alterations in bacterial numbers, type, and metabolic capabilities. The many laboratory studies in rats have been difficult to interpret since powerful initiators of carcinogenesis are always required and this rather than the promotion of spontaneous neoplastic change is the sine qua non for tumor growth in this situation. The current dilemma highlights the lack of knowledge of most aspects of human colonic physiology. Until these issues are more clearly resolved the epidemiological leads would point to low fat diets rich in less processed starchy foods with increased fiber as possible protection. Such advice is in common with the pronouncements of heart foundations, diabetes associations, and recommendations of official bodies to the general public.

Animals↗
PubMed1985

Low glycemic index carbohydrate foods in the management of hyperlipidemia.

Reduction in the mean glycemic index (GI) of diets of 12 hyperlipidemic patients from 82 +/- 1 to 69 +/- 2 units (p less than 0.001) for a 1 mo period resulted in a significant reduction in total and LDL serum cholesterol and serum triglyceride by comparison with the mean lipid values for the preceding and following control months. The change in GI of the diet was achieved largely through manipulation of the cereal products and was not related to large differences in the amount of dietary fiber. In addition, apart from a small mean increase in unsaturated fat and calorie intake during the control periods, no difference was seen between the proportion of macronutrients on either treatment as determined by 1 wk diet histories recorded on alternate weeks throughout the 3 mo study. Selection of low glycemic index foods may therefore be a useful adjunct to the management of hyperlipidemia.

Adult↗
PubMed1985

Specific antibody responses to Taenia hydatigena, Taenia pisiformis and Echinococcus granulosus infection in dogs.

Groups of dogs reared free of both nematodes and cestodes were infected with Taenia hydatigena, Taenia pisiformis or Echinococcus granulosus. After infections with the Taenia spp became patent, dogs were purged to remove the worms. They were later reinfected and the second infections again removed by purging after patency. A group of 3 uninfected worm free dogs was kept as age-matched controls. The dogs were bled at intervals of 5 days and their serums tested for antibodies using the enzyme-linked immunosorbent assay (ELISA) with excretory/secretory (ES) antigens collected during in vitro incubation of evaginated scoleces (scolex ES antigen) and oncosphere antigens. Antibodies to scolex ES antigen were detected by 3 weeks after infection with each cestode species whereas antibodies to oncosphere antigen were not detected until about one week after eggs were found in the faeces of the infected dogs. Antibody responses to both oncosphere and scolex ES antigens decreased rapidly following removal of the worms by purging. Uninfected control dogs were invariably negative to both oncospheral and scolex ES antigens. There were cross-reactions between the serums from dogs infected with T. pisiformis and T. hydatigena when tested with scolex ES antigens, but oncospheral antigens showed a high degree of species specificity. Scolex ES antigens from E. granulosus were compared with those prepared from T. hydatigena and T. pisiformis for their ability to discriminate between antibodies in serums collected from dogs 31 and 32 days after infection with 100,000 protoscoleces of E. granulosus or dogs infected with Taenia spp.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Dietary fiber and the glycemic response.

Addition of purified fiber to carbohydrate test meals has been shown to flatten the glycemic response in both normal and diabetic volunteers, reduce the insulin requirement in patients on the artificial pancreas and in the longer term reduce urinary glucose loss and improve diabetes control. In the context of high fiber-high carbohydrate diets these findings have had a major impact in influencing recommendations for the dietary management of diabetes internationally. The mechanism of action appears in part to be due to the effect of fiber in slowing absorption rather than by increasing colonic losses of carbohydrate. Consequently postprandial GIP and insulin levels are reduced and the more viscous purified fibers (e.g., guar and pectin) appear most effective. In addition it has been suggested that colonic fermentation products of fiber may enhance glucose utilization. More recently it has become clear that many aspects of carbohydrate foods (food form, antinutrients, etc.) in addition to fiber may influence the rate of digestion and has led to a classification especially of starchy foods in terms of glycemic index to define the degree to which equicarbohydrate portions of different foods raise the blood glucose. Use of such data may maximize the effectiveness of high carbohydrate and high fiber diets in the management of diabetes and related disorders.

Blood Glucose↗