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Biomedical subjects

K K Stewart

Publications and source records attributed to K K Stewart.

15 recordsLinked to original sources
PubMed2001

Long-term stability of nutrients in a frozen mixed food control material.

A mixed food homogenate was prepared as a quality control material for two multi-center clinical feeding trials. Approximately 100 kg of homogenized human diet material was prepared under controlled conditions to maintain the stability of lipid components. More than 4,800 20-25 g aliquots were prepared and stored at -60 degrees C in glass jars with Teflon-lined lids. The homogeneity of the composite was validated by analysis of moisture and total fat in aliquots taken throughout the dispensing sequence. A portion of the material was reserved at the National Institute of Standards and Technology and further characterized as SRM 1544-Fatty Acids in Diet Composite. Moisture, protein, ash, total lipid, fatty acids, cholesterol, sodium, potassium, calcium, and magnesium were assayed as part of routine quality-control analyses. Components were analyzed over a total time period ranging from 29 months (minerals) to 60 months (moisture), and up to 319 values per nutrient were generated. Results for all components assayed were stable over the time period studied. For example, moisture (n = 319; 60 months) ranged from 70.66 to 72.58 g/100 g with a mean, standard deviation (SD), and relative standard deviation (RSD) of 71.90, 0.27, and 0.4%, respectively. The range, mean, SD, and RSD for cholesterol (mg/100 g; n = 98; 49 months) were 13.54-17.96, 15.14, 0.64, and 4%.

Diet↗
PubMed1999

Validation of diet composition for the Dietary Approaches to Stop Hypertension trial. DASH Collaborative Research Group.

The Dietary Approaches to Stop Hypertension trial involved 4 clinical sites at which 459 participants (in 5 cohorts) were fed 3 dietary patterns over 11 weeks per cohort. The 3 patterns were a control diet, a fruits and vegetables diet, and a combination diet. Before the intervention, key nutrient levels in each diet were validated at 2 energy levels (2,100 and 3,100 kcal) by chemical analysis of the prepared menus. During intervention, diets were sampled across all cohorts, sites, and energy levels, and 7-day menu cycle composites were assayed. In general, sodium, potassium, calcium, and magnesium in the validated menus for each diet/energy level met the nutrient targets, though moderate variability was evident among individual menus, particularly for potassium, calcium, and magnesium. However, as intended, there was clear separation and no overlap in mineral levels in individual menus of diets that were designed to differ. During intervention, macronutrient contents met nutrient goals. Sodium, potassium, calcium, and magnesium in the diets generally met target levels, though potassium in the fruits and vegetables diet was 11% to 23% below target. There were no consistent differences in nutrient levels between sites. The mean nutrient levels in the validated menus and diets sampled during intervention were in excellent agreement with each other, though sodium was somewhat higher (approximately 6%) in the diets from intervention vs validation. These results indicate the success of the quality control measures implemented and suggested consistent overall diet composition throughout the 28 months during which the study was conducted.

Blood Pressure↗
PubMed1996

Effects of dietary taurine on growth and Escherichia coli resistance in chickens.

White Leghorn chicks selected for either high (HA) or low (LA) antibody response to SRBC were used in two experiments to ascertain the effects of differing levels of dietary taurine on growth, levels of taurine in blood plasma, heart, and brain, and response to Escherichia coli inoculation. A different level of dietary taurine was associated with maximal growth in each of the two selected populations. Line HA expressed greater growth with a relatively low level of taurine, whereas Line LA expressed greater growth with a relatively high level of taurine. Line LA chicks had a higher level of taurine in the heart than did Line HA chicks. Although increases in dietary taurine resulted in linear and curvilinear increases in plasma and heart taurine levels, they had no effect on brain levels. No apparent resistance or susceptibility to E. coli exposure was associated with stock or differing levels of dietary taurine.

Animals↗
PubMed1991

Under-reporting of contaminated needlestick injuries in emergency health care workers.

STUDY HYPOTHESIS: There is considerable under-reporting of contaminated occupational needlestick and other sharp object injuries among emergency health care workers. POPULATION: A convenience sample of emergency physicians, emergency nurses, and emergency medical technicians (EMTs). METHODS: A survey instrument eliciting demographic and work-related factors was developed and administered; survey items included age, sex, occupation, years in occupation, number of procedures performed per week, number of contaminated needlestick (and other "sharps") injuries recalled, and number of these injuries formally reported during the previous five years. Nonsegmented visual analog scales were used to assess eight attitudes possibly associated with nonreporting. Analysis was by analysis of variance and multiple linear regression with stepwise variable election. RESULTS: Two hundred fifty-nine subjects recalled 643 contaminated exposures during the five-year study period, but only 228 (35%) were formally reported. One or more injuries occurred in 55% of EMTs compared with 72% of nurses and 80% of physicians (P less than .05). Physicians recalled a mean of 3.8 contaminated exposures, whereas nurses recalled 2.8 and EMTs recalled only 1.8 (P less than .05). Physicians formally reported a mean of 0.26 exposures, whereas EMTs reported 0.85 and nurses reported 1.25 (P less than .05). Physicians formally reported only one eighth of their injuries compared with EMTs and nurses, who each reported two thirds of these events (P less than .05). Perception of risk, occupation, years in occupation, and concern about excessive paperwork were the most powerful predictors of low reporting rate (P less than .05). CONCLUSIONS: Work-related contaminated sharp object injuries are under-reported by emergency health care workers, especially emergency physicians.

Accidents, Occupational↗
PubMed1980

Automated multiple flow-injection analysis in clinical chemistry: determination of albumin with bromcresol green.

We describe an adaptation of automated multiple flow-injection analysis instrumentation to an analysis for albumin in serum. The bromcresol green reaction was used to test the utility of the system. The approach yielded albumin results with excellent sensitivity, no measurable carryover, a relative standard deviation of less than 1%, good correlations with published procedures, and no measurable interferences. The simplicity and flexibility of the instrumentation and its performance integrity, as indicated by the analytical results, make this a viable clinical chemical tool.

Bromcresol Green↗
PubMed1980

Automated multiple flow-injection analysis in clinical chemistry: determination of total protein with Biuret reagent.

We have examined the feasibility of the automated multiple flow-injection technique for application to clinical chemistry by adapting to this system the biuret method for the determination of total protein. Samples were discretely and rapidly introduced into a continuously flowing, nonsegmented reagent stream by means of an automatic sampler and high-pressure injection valve. Pumps operating at 1380-2070 kPa (200-300 psi) were utilized to introduce the biuret reagent and saline diluent into the system separately at flow rates of 72 and 47 microL/s, respectively. Use of 20-microL sample and a 3.0-s reaction-delay coil was adequately sensitive for analysis for total protein by this method. Samples were analyzed at a rate of 150/h with no detectable between-sample carryover. Within-run precision studies yielded relative standard deviations of 2.5% and less. Total protein values obtained by this method correlated well with those obtained by centrifugal analyzer and bubble-segmented continuous-flow biuret methods.

Autoanalysis↗
PubMed1978

Proteinase inhibitors from the excretory gland cells of Stephanurus dentatus. Purification and properties of three secretory proteinase inhibitors.

Three proteinase inhibitors designated as I, II, and III were isolated from the excretory gland cells of the swine kidney worm, Stephanurus dentatus. The inhibitors, which were trichloroacetic acid-soluble, were purified by affinity chromatography and ion exchange chromatography. The homogeneity of each inhibitor was shown by polyacrylamide gel electrophoresis and electrofocusing. The molecular weights of the inhibitors estimated by sodium dodecyl sulfate gel electrophoresis fell within a limited range of 9300 to 9700, and the isoelectric points were 6.45, 6.20, and 5.34 for Inhibitors I, II, and III, respectively. The inhibitors formed complexes with trypsin having apparent dissociation constants (Ki) of 2.9 X 10(-11), 7.6 X 10(-11), and 6.4 X 10(-11) M, respectively. Each inhibitor inhibits the esterolytic and proteolytic activities of both trypsin and chymotrypsin. A proteinase inhibitor present in the reproductive organs, intestines, body walls, and esophagi was identical with Inhibitor II found in the excretory gland cells. Culture medium collected after 24-h incubation with adult worms contained the same three inhibitors as the excretory gland cells. These data suggest that the gland cells may secrete the inhibitors internally and externally.

Amino Acids↗
PubMedDate not supplied

Fine tuning a bile-enzymatic-gravimetric total dietary fiber method.

A recently proposed bile-enzymatic-gravimetric total dietary fiber (TDF) method was modified and the new procedure was compared with the original method, the traditional AOAC enzymatic-gravimetric determination (AOAC Official Method 985.29), and another simplified AOAC procedure by analyzing several diet composites, including National Institute of Standards and Technology 1548 total diet reference material. The original and modified bile-enzymatic-gravimetric procedures also were compared by analyzing 9 food samples from a collaborative study of the original method. The modified method consistently yielded values about 10% lower than the original method but closer to reference values and to values from AOAC Official Method 985.29, suggesting results that are more in line with accepted TDF standard methodology. Our modified method was used to analyze 180 fresh-frozen diet composites with TDF values ranging from 0.6 to 3.2 g/100 g wet weight. Samples were from 2 multicenter feeding studies sponsored by the National Heart, Lung and Blood Institute: DELTA (Dietary Effects on Lipoproteins and Thrombogenic Activity) and DASH (Dietary Approaches to Stop Hypertension). The mean relative standard deviation (RSD) for duplicate analyses was 1.1%. For 40 assays of a quality control diet composite over 9 months, the standard deviation was 0.1 g/100 g wet weight (4.9% RSD), indicating the method's excellent precision for routine use.

Diet↗
PubMedDate not supplied

Effect of seeds on bile-enzymatic-gravimetric analysis of total dietary fiber.

Dietary fiber sometimes is defined chemically as nonstarch polysaccharides plus lignin or as other specific chemical entities. Analysis of dietary fiber according to a chemical definition typically involves gas chromatography, which allows separation and quantitation of chemical constituents that are added to arrive at a dietary fiber value. Other definitions of fiber are broader, defining it to be whatever is not digested in the alimentary tract. Analytically, this definition translates into the gravimetric sum of the material remaining after a series of enzymatic and chemical treatments that simulate in vivo digestion. Various methods reflect the gravimetric definition, which might include as dietary fiber some protein, resistant starch, and even lipids that are not digested by particular assay conditions. We used a recently proposed bile-enzymatic-gravimetric assay for total dietary fiber on commonly consumed seeds (hulled and unhulled sesame, caraway, and poppy) and visually found these seeds to be undigested. We then determined the impact of the undigested seeds on measured dietary fiber content by spiking homogenized daily menus with 5% by weight of these seeds and calculating recoveries with 2 assumptions: seeds are 100% fiber because they are not digested, and the fiber content of seeds is as determined by assay. Calculated recoveries were very different depending on which assumption was made (71-90% or 99-109%, respectively), and the difference was closely related to the seed's protein content.

Bile↗