RS Levels Research Articles

P1-07-11: Consistency and Control in Clinical Assay Technology over Time: The Oncotype DX Recurrence Score and Assessment of Single Gene Expression Levels.

Abstract Background: ASCO® and CAP have recently highlighted the importance of consistency and control in clinical assay technology. To date the Oncotype DX® Recurrence Score® (RS) has been ordered to assist in individualized treatment decision making in over 200,000 estrogen receptor positive, early stage breast cancer patients. The assay quantifies gene expression using RT-PCR from fixed paraffin embedded tissue (FPET) and employs a large number of controls and calibrators to enhance precision and reproducibility. Over 6 years of data on the assay presents an opportunity to explore consistency over time in the RS and quantitative single gene levels (ER, PR, HER2). Methods: All tumors successfully analyzed in the Genomic Health Laboratory from 1/1/05-3/31/11 were included. Descriptive statistics for the RS, the average reference gene expression level, and expression levels for quantitative single genes were obtained for each calendar year. This was done for the entire data set as well as for subgroups defined by histological tumor type. The associations by year between HER2 and GRB7, ER and HER2, and ER and PR expression levels were explored including scatterplots and summary statistics. Results: There were a total of 207,691 breast cancer cases, and the number in each calendar year increased over time as shown in the Table. In general the median age increased slightly over time, as did the proportion of patients in the low RS Risk Group. There was no systematic change over time in the average reference gene expression level, or in the expression levels for the individual genes ER, PR or HER2 during the period from 2008 to 2011 when individual gene testing was provided as part of the Oncotype DX assay report. The relationships between HER2 and GRB7, ER and HER2, and ER and PR remained consistent over time. Conclusions: Active monitoring of the Oncotype DX assay as mandated by ASCO/CAP shows a high degree of consistency in results for both the multigene Recurrence Score and the quantitative single gene results. These results and the approaches used for monitoring consistency are relevant to other institutions in their efforts to maintain and improve assay quality control. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P1-07-11.

The effect of chemically‐modified resistant starch, RS type‐4, on body weight and blood lipid profiles of high fat diet‐induced obese mice

AbstractThis study was conducted to investigate the effects of feeding chemically‐modified resistant starch type‐4 (RS4) of normal (NCS) and high‐amylose corn starch (HACS) on weight gain and plasma and liver lipid profiles of mice fed a high‐fat diet (HFD). The experimental four groups were, respectively, fed following diets: A 40% HFD with NCS, HACS, NCS‐ and HACS‐RS4. A normal diet (ND) group of mice fed the standard diet was also used as control. In order to produce RS4 by chemical modification, corn starches were treated with STMP/STPP. Total RS (TRS) and total dietary fiber (TDF) levels of chemically‐modified NCS were 26.4 and 44.0%, respectively, while TRS and TDF levels in chemically‐modified HACS were 78.1 and 78.5%, respectively. Onset gelatinization temperatures of both modified corn starches clearly shifted to higher temperatures after STMP/STPP treatment. At the end of the diet trial, the mice on the HACS diet decreased body weight gain compared to the NCS‐fed mice. Adding NCS‐ and HACS‐RS4 to the diet significantly reduced the weight gain relative to NCS and HACS groups. Both RS4 diets were effective in improving the lipid profile compared to their respective controls. They significantly reduced the level of total lipid and total cholesterol.

The effects of annealing and acid hydrolysis on resistant starch level and the properties of cross‐linked RS4 rice starch

AbstractThe effects of ANN prior to cross‐linking of non‐wx rice starches on a RS level and granular shape were investigated to apply them for a fat replacer with RS in a liquid food system. Acid hydrolysis and sonication were also evaluated to improve RS quality. The RS level was also compared with AOAC and P/G methods. The RS levels of CRS analyzed with the AOAC method were higher than those analyzed with the P/G method, but the differences in the RS level of CRS affected an ANN condition and starch content during cross‐linking. When ANN was conducted at 50°C for 12 h using the AOAC method, and starch content (40%) used in cross‐linking was at 45°C for 3 h, the highest RS level of CRS treated with ANN was 69.4% compared to 38.3% RS level of CRS without ANN. The 1 h acid hydrolysis (pH 4.0) of CRS treated ANN increased 114.5% of the RS level (79.4% compared to 69.4% in CRS treated ANN), regardless of which analytical methods were used. CRS granules remained the same as native ones with a polygonal shape and A type crystallinity even after being treated with ANN, and acid hydrolysis. The sonication before cross‐linking reaction increased the RS level and prevented increase in size from aggregating CRS granules.

Effect of controlled gelatinization in excess water on digestibility of waxy maize starch

Abstract An aqueous dispersion of waxy maize starch (5%, w/w) was controlled gelatinized by heating at various temperatures for 5 min. The treated samples were analysed using in vitro Englyst assay, light microscopy, differential scanning calorimetry, X-ray diffraction, and Fourier-transform infrared spectroscopy. When heated, SDS and RS levels were decreased inversely with RDS. A high SDS content (>40%) was kept prior to the visible morphological and structural changes (before 60 °C). Swelling factor began to increase slightly at 50–60 °C and continued to maximum value at 80 °C. A large decrease in ΔH, crystallinity, and ratio of 1047/1022 cm−1 attributed to partially dissociation of crystalline clusters and double helices occurred at 65–80 °C. These changes showed that controlled gelatinized starch with slow digestion property occurred in the molecular rearrangement process before granule breakdown and SDS mainly consists of amorphous regions and a small portion of less perfect crystallites.

In vitro Digestibility of Cross‐Linked Starches – RS4

AbstractIn vitro digestibility of cross‐linked starches (RS4 type), which were prepared from wheat, corn, rice, potato, and high‐amylose corn starches, was determined by Prosky AOAC and pancreatin gravimetric (P/G) methods. The RS levels of RS4 starches obtained by the AOAC method were higher than those by the P/G method. Pronase treatment before digestion with heat‐stable α‐amylase (AOAC method) gave similar RS levels as those by P/G method. The shapes of residues after digestion by the AOAC method were not different from untreated ones, but those after digestion by the P/G method showed irregular and fluffy forms. It was found that the P/G method provided more exhaustive digestion of RS4 starches than the AOAC method.

Cross‐Linked Resistant Starch: Preparation and Properties

ABSTRACTResistant starches (RS) were prepared by phosphorylation of wheat, waxy wheat, corn, waxy corn, high‐amylose corn, oat, rice, tapioca, mung bean, banana, and potato starches in aqueous slurry (≈33% starch solids, w/w) with 1–19% (starch basis) of a 99:1 (w/w) mixture of sodium trimetaphosphate (STMP) and sodium tripolyphosphate (STPP) at pH 10.5–12.3 and 25–70°C for 0.5–24 hr with sodium sulfate or sodium chloride at 0–20% (starch basis). The RS4 products contain ≤100% dietary fiber when assayed with the total dietary fiber method of the Association of Official Analytical Chemists (AOAC). In vitro digestion of four RS4 wheat starches showed they contained 13–22% slowly digestible starch (SDS) and 36–66% RS. However after gelatinization, RS levels fell by 7–25% of ungelatinized levels, while SDS levels remained nearly the same. The cross‐linked RS4 starches were distinguished from native starches by elevated phosphorus levels, low swelling powers (≈3g/g) at 95°C, insolubilities (<1%) in 1M potassium hydroxide or 95% dimethyl sulfoxide, and increased temperatures and decreased enthalpies of gelatinization measured by differential scanning calorimetry.

Strategies for the manufacture of resistant starch

Starch not hydrolyzed in the small intestine is considered to be enzyme-resistant starch (RS). Because individuals differ in their ability to digest starch, there is no absolute distinction between RS and digestible starch. A method for in vitro determination of RS should be validated using a human population average value. In any starch material, the constituent molecules will have a range of susceptibility to amylolytic activity in vitro. For a starch or starch-containing ingredient it is possible to alter this range by judicious selection of processing conditions to increase the proportion that tests as RS. The starch material will also have a range of thermal stabilities before and after processing, which may or may not reflect the range of susceptibility to hydrolysis. The manufacture of RS may be thought of as enhancement of the proportion of the starch that tests as RS. To compare the effect of different processing schemes, it is critical to stipulate the method used to estimate RS content. This review focuses on strategies for increasing the proportion of types 2 and 3 RS in a starch-containing ingredient. Special emphasis is given to increasing RS levels of granular starch.

Quantitation of soluble E-receptor of T lymphocytes in serum from HIV-1 positive patients.

Human T lymphocytes carry a membrane receptor for sheep erythrocytes (E) related to the CD2 molecule. The E-receptor is found in a soluble from (Rs) in serum and can be quantitated by "rocket electrophoresis" using an anti-Rs serum obtained by immunizing sheep with autologous erythrocytes coated with Rs. Increased serum levels of Rs are found in patients with diseases associated with immunodepression. In the present study, 14 asymptomatic HIV-1 seropositive individuals were investigated regarding their Rs levels and delayed hypersensitivity skin tests every 3 months for a period of 35 months. All these patients progressed to AIDS in this period. Rs serum levels have also been quantitated in 14 normal individuals. The mean Rs values in normal individuals, asymptomatic, and AIDS patients were, respectively: 4.8 +/- 1.5 mm (SD), 9.6 +/- 1.9 mm (SD) and 11.3 +/- 2.4 mm (SD). An increase of Rs serum levels was observed when we compared normal individuals with CDC-II and CDC-IV clinical stage patients (P < 0.05, Mann-Whitney test) and CDC-II and CDC-IV patients, (P < 0.05, Wilcoxon test). We have observed a depressed delayed hypersensitivity response to ubiquitous antigens in CDC-IV patients. Our results indicate that Rs serum levels can be used as a progression marker in HIV infected patients.

Effectiveness of resistant starch, compared to guar gum, in depressing plasma cholesterol and enhancing fecal steroid excretion

Amylase-resistant starch (RS) represents a substrate that can be administered in substantial amounts in the diet, in contrast to gel-forming polysaccharides, such as guar gum (GG). The aim of this work was thus to compare the effects of GG and RS on cholesterol metabolism in rats adapted to 0.4% cholesterol diets, using dietary GG or RS levels (8 or 20%, respectively) that led to a similar development of fermentations, as assessed by the degree of enlargement of the cecum. The RS diet elicited a marked rise in the cecal pool of short-chain fatty acids, especially acetic and butyric acid, whereas the GG diet favored high-propionic acid fermentations. Both polysaccharides markedly altered the cholesterol excretion, from 50% of ingested cholesterol in controls, up to about 70% in rats adapted to the RS or GG diets. With these diets, the fecal excretion of bile acids was enhanced (67 and 144% with the RS and GG diets, respectively). RS and GG diets were effective in lowering plasma cholesterol (about -40%) and triglycerides (-36%). There was practically no effect of the diets on cholesterol in d > 1.040 lipoproteins (high density lipoproteins), whereas RS (and to a larger extent, GG) were very effective to depress cholesterol in d < 1.040 lipoproteins (especially in triglyceride-rich lipoproteins). Fermentable polysaccharides counteracted the accumulation of cholesterol in the liver, especially cholesterol esters. In parallel, liver acyl CoA:cholesterol acyltransferase was depressed in rats fed the RS or GG diets, whereas only the GG diet counteracted the downregulation of 3-hydroxy-3-methylglutaryl-CoA by cholesterol. These data suggest that RS may be practically as effective as a gel-forming gum, such as GG, on steroid excretion and on cholesterol metabolism.