Craig A Hassel

Raising intestinal contents viscosity leads to greater excretion of neutral steroids but not bile acids in hamsters and rats

To examine the effect of intestinal contents viscosity on fecal steroid excretion independent of colonic fermentation, hamsters and rats were fed cholesterol-containing diets containing either cellulose or different viscosity grades of hydroxypropyl methylcellulose (HPMC), a non-fermentable fiber, as the dietary fiber source. HPMC feeding relative to cellulose significantly lowered plasma cholesterol in hamsters and liver cholesterol in rats. Fecal neutral steroid excretion was significantly greater in both species consuming HPMC compared to cellulose. Fecal bile acid excretion was not altered in hamsters, but was reduced in rats fed HPMC compared to cellulose. Thus, greater intestinal contents supernatant viscosity results in reduced plasma (hamster) or liver (rat) cholesterol and greater neutral steroid excretion, whereas bile acid excretion is unaffected or reduced. This suggests that viscosity is the principal characteristic of dietary fiber responsible for cholesterol lowering, and that this effect is due to increased excretion of cholesterol from the body.

New Moccasins: Articulating Research Approaches through Interviews with Faculty and Staff at Native and Non-Native Academic Institutions

OBJECTIVE The goals of this study were to explore the perceptions of professionals concerning research, its different approaches, and appropriate future directions with Native American communities, particularly in relation to nutrition issues. DESIGN Semistructured qualitative interviews. setting: Interviews were conducted at Native and non-Native academic institutions, at other relevant locations, and over the telephone. PARTICIPANTS Participants (N = 20) were from Native and non-Native academic institutions and had experience working with research in Native American communities. PHENOMENA OF INTEREST Relationships between Native and non-Native academic institutions, worldviews regarding research and American Indian communities, and beneficial research within American Indian communities. ANALYSIS Interviews were audiotaped, transcribed verbatim, and returned to the participants for review. Analysis of interview material involved eliciting themes. RESULTS Some participants acknowledged different cultural worldviews in relation to research. Many participants provided insight on how to define beneficial research. Most said building trust between Native and non-Native academic institutions is an important step in developing effective research relationships. CONCLUSIONS AND IMPLICATIONS These findings are a first step toward creating a more equitable process of research that acknowledges different cultural worldviews and values community involvement within Native American communities.

Lipoprotein receptors in copper-deficient rats: apolipoprotein E-free high density lipoprotein binding to liver membranes

Twenty-four male weanling Sprague-Dawley rats were randomly and equally divided into two dietary treatments, copper-deficient and adequate (0.7 mg and 8.0 mg Cu/kg diet, respectively). Deionized water and diet were provided ad libitum. After 8 weeks, rats were exsanguinated, membranes prepared from livers, and plasma high density lipoproteins (HDL) isolated by ultracentrifugation and agarose column chromatography. Heparin-sepharose affinity chromatography was used to isolate subfractions of HDL devoid of apolipoprotein E (apo E-free HDL). The apo E-free HDL derived from rats of each dietary treatment were iodinated and bound to liver membranes prepared from rats of both treatment groups. Total binding data, specific binding data, and computer derived estimates of maximum equilibrium binding (Bmax) indicate less binding was observed when lipoproteins and membranes from copper-deficient animals were used in the binding assay compared to controls. In addition, a 2 X 2 factorial analysis of binding parameters derived from all experiments demonstrated a significant lipoprotein effect, indicating the reduction in binding may be associated with apo E-free HDL obtained from copper-deficient rats. The present findings suggest a reduction in binding of apo E-free HDL to their binding sites may contribute to the hypercholesterolemia and hyperlipoproteinemia observed in copper deficiency.

Alterations in Lipid Composition and Fluidity of Liver Plasma Membranes in Copper-Deficient Rats

Abstract In view of the importance of membrane fluidity on cell functions, the influence of phospholipid acyl groups on membrane fluidity, and the changes in lipid metabolism induced by copper (Cu) deficiency, this study was designed to examine the influence of dietary Cu on the lipid composition and fluidity of liver plasma membranes. Male Sprague–Dawley rats were divided into two dietary treatments, namely Cu deficient and Cu adequate. After 8 weeks of treatment, liver plasma membranes were isolated by sucrose density gradient centrifugation. The lipid fluidity of plasma membranes, as assessed by the intramolecular eximer fluorescence of 1,3-di(1-pyrenyl) propane, was significantly depressed by Cu deficiency. In addition, Cu deficiency significantly reduced the content of arachidonic and palmitoleic acids but increased the docosatetraenoic and docosahexaenoic acids of membrane phospholipids. This alteration in unsaturated phospholipid fatty acid composition, especially the large reduction in arachidonic acid, may have contributed to the depressed membrane fluidity. Furthermore, Cu deficiency also markedly altered the fatty acid composition of the triacylglycerols associated with the plasma membranes. Thus, the lipid composition and fluidity of liver plasma membranes are responsive to the animals Cu status.

Apolipoprotein E-rich HDL binding to liver plasma membranes in copper-deficient rats

Abstract Copper deficiency in rats raises plasma cholesterol concentration while reducing liver cholesterol concentration. One consequence of this cholesterol redistribution is the accumulation of a large high-density lipoprotein (HDL) particle rich in apolipoprotein E (apo E). The purpose of this study was to determine, using an in vitro binding assay, if the interaction of apo E-rich HDL with hepatic lipoprotein binding sites may be affected by copper deficiency. Male Sprague-Dawley rats were divided into two dietary treatments (copper-deficient and -adequate) and placed on a dietary regimen for 8 weeks. Subsequent to exsanguination, hepatic plasma membranes were prepared and apo E-rich HDL was isolated from rats of each treatment by ultracentrifugation, agarose column chromatography, and heparin-Sepharose affinity chromatography. Total binding and experimentally derived specific binding of 125I-apo E-rich HDl to hepatic plasma membranes indicated greater binding when lipoproteins and membranes from copper-deficient animals were used in the assay compared to controls. Scatchard analysis of specific binding data indicated that equilibrium binding affinity (Kd ) was also affected by copper deficiency. The hepatic binding sites recognizing apo E-rich HDL were not affected by EDTA or pronase, of relatively high capacity, and recognized a variety of other rat lipoproteins.

Evaluation of a Decision Case Approach to Food Biotechnology Education at the Secondary Level

Abstract This paper describes an evaluation of a decision case approach used with secondary students to address labeling of genetically engineered foods. The decision case study was implemented in science, horticulture, food science, and biology classes by eight teachers in a total of six public and private urban, suburban, and rural high schools. After the case experience, students were more positive about the use of biotechnology in food production and fewer advocated special labeling for genetically engineered products. Most students rated their level of involvement in the decision case as moderate or high and indicated that the case study was both a positive and a learning experience.

Cholesterol-lowering effects of modified animal fats in postmenopausal women

OBJECTIVE In an attempt to improve the nutritional value of animal fats (including milkfat and lard), two technological approaches (i.e., cholesterol removal by steam distillation and linoleic acid enrichment by addition of safflower oil) were tested for cholesterolemic effects in a cohort of 29 older women (age 68 +/- 7 years). METHODS Test fat sources were incorporated into crackers, cookies, cheese, ice cream, whipped topping, sour cream, baking shortening, and table spreads. Subjects were permanent residents of a convent where meals were prepared in a centralized kitchen, allowing test fats to be provided in daily food menu items. The foods containing test fats were introduced into three sequential dietary treatment periods, each lasting 4 weeks, in the following order: cholesterol-reduced animal fat (CRAF): fatty-acid modified, cholesterol-reduced animal fat (FAMCRAF); and-unaltered animal fat (AF). Subjects were offered menu items cafeteria style and encouraged to make food selections consistent with their habitual diets, which were recorded daily. RESULTS Fasted blood lipid profiles determined at the end of each treatment period showed that FAMCRAF reduced mean plasma total cholesterol, LDL cholesterol, and apolipoprotein B concentrations relative to AF (p < 0.05). Mean HDL cholesterol concentrations were not influenced by diet. DISCUSSION Relative to native products, animal fats modified by cholesterol removal and linoleic acid enrichment reduced plasma total and LDL cholesterol concentrations in a predictable manner similar to that based on studies of men.

Using Chinese medicine to understand medicinal herb quality: An alternative to biomedical approaches?

Chinese medicine (CM) is one ofseveral ancient systems of medical care basedupon a different worldview than the prevailingbiomedical model; it employs its own language,systems of logic, and criteria forunderstanding health and diagnosing illness.Medicinal herbs play a central role in the CMsystem of practice and knowledgeable CMpractitioners have extensive clinicalexperience using them. However, the establishedscientific and regulatory organizations thatrely upon biomedical understandings ofpathology do not accept the definitions formedicinal herb quality used by CMpractitioners. Furthermore, local medicinalherb growers within the upper Midwest are in aposition to grow many herbs, but are unclearabout the demand for and desired qualities ofthe medicinal herbs they produce. Given thissituation, the Medicinal Herb Network wasfounded as a partnership effort of small-scalemedicinal herb growers and practitioners of CMto develop more appropriate standards ofmedicinal herb quality and to encourage locallygrown, high quality medicinal herbs consistentwith these standards. An overview of CM servesas grounding from which to articulate thedilemmas experienced by CM practitioners ofperceiving medicinal herb quality andintegrating knowledge across divergent medicalsystems. A Network initiative designed toovercome these dilemmas illustrates thepossibility of developing a lexicon of qualitydescriptors for medicinal herbs using Chinesemedical theory, while drawing from descriptivesensory analysis procedures currently practicedby a sub-group of food scientists.

Binding of low density and very low density lipoproteins to liver plasma membranes of copper-deficient rats.

Abstract The binding of rat LDL and rabbit β-VLDL to liver plasma membranes of copper-deficient rats was examined. Characterization experiments demonstrated binding of both lipoprotein fractions to be relatively insensitive to treatment with pronase, EDTA, excess CaCl 2 , or heparin. Competitive displacement experiments demonstrated that the binding reaction is not dependent on specific apolipoprotein ligands and imply a nonspecific binding site. These results indicate binding independent of the LDL or chylomicron remnant receptor. Copper deficiency had no effect on the total binding of either LDL or β-VLDL over a wide range of label concentration. The data indicate that hepatic membranes from copper-deficient rats do not exhibit altered binding capacity for LDL or β-VLDL and provide evidence that an impairment in receptor-mediated binding of lipoproteins does not contribute to the hypercholesterolemia observed in copper-deficient rats.

Nutrition Education: Toward a Framework of Cultural Awareness.

Adopting a framework of cultural awareness creates challenges for nutrition education that go well beyond introducing culturally diverse foodways or recruiting culturally diverse bodies into the fold of mainstream nutrition education, although both of these actions are needed. A framework of cultural awareness recognizes culture as foundational to human thought, including “scientific” thought. It locates the Eurocentric cultural grounding of nutrition sciences and nutrition education as formally taught in higher education. A framework of cultural awareness calls attention to background assumptions such as universality, materialism, control over nature, objectivity, reductionism, and value-neutrality as implicit Eurocentric cultural ground. Adopting a framework of cultural awareness asks nutrition educators to consciously locate themselves and their knowledge within a cultural context. The practice of cross-cultural engagement (CCE) is glimpsed through the Woodlands Wisdom model of nutrition education, developed with leadership from a confederation of tribal colleges. CCE offers a means for academic educators and learners to use a cultural awareness framework to culturally situate their own educational background and develop capacity to navigate the complex terrain of interfacing culturally different forms of knowledge. Are nutrition educators ready to confront the challenges and opportunities that come with adopting a framework of cultural awareness?