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Biomedical subjects

J C Peters

Publications and source records attributed to J C Peters.

At least 19 recordsLinked to original sources

Long-term effects of dietary organic and inorganic selenium sources and levels on reproducing sows and their progeny.

An experiment evaluated the effects of feeding either a basal non-Se-fortified diet, two Se sources (organic or inorganic) each providing 0.15 and 0.30 ppm Se, or their combination (each providing 0.15 ppm Se) on gilt growth and sow reproductive performance. The experiment was a 2 x 2 + 2 factorial conducted in a randomized complete block design in three replicates. One hundred twenty-six crossbred gilts were started on one of the six treatment diets at 27.6 kg BW. During the grower phase, animals were bled at 30-d intervals with three gilts killed per treatment at 115 kg BW for tissue Se analysis. Fifteen gilts per treatment were bred at 8 mo of age and were continued on their treatment diets for four parities. Sow serum collected within parity was analyzed for Se and glutathione peroxidase (GSH-Px) activity. Tissue Se was determined from five 0-d-old pigs per treatment from fourth-parity sows. Three sows per treatment were killed after the fourth parity for tissue Se analysis. Similar treatment performance responses occurred from 27 to 115 kg BW. Serum Se (P < 0.01) and GSH-Px activity (P < 0.05) increased for both Se sources to 0.30 ppm Se during the grower and reproductive periods. Serum Se and GSH-Px activity decreased from 70 to 110 d postcoitum in all treatment groups, but increased at weaning (P < 0.01) in the Se-fortified groups. The number of pigs born (total, live) increased (P < 0.05) with the 0.15 ppm Se level for both Se sources. Tissue and total body Se content of 0-d-old pigs increased with Se level (P < 0.01) and also when the organic Se source (P < 0.01) was fed to the sow. When sows were fed either Se source, pig serum Se (P < 0.01) and GSH-Px activity (P < 0.05) increased at weaning. Colostrum and milk Se concentrations increased (P < 0.01) with Se level for both Se sources, but were substantially greater (P < 0.01) when sows were fed organic Se. The combination of Se sources had sow milk and tissue Se values that were similar to those of sows milk and fed 0.15 ppm organic Se. The fourth-parity sows had greater tissue Se concentrations when organic Se level was increased (P < 0.01), more so than when sows were fed inorganic Se. These results suggest that both Se sources resulted in similar sow reproductive performances at 0.15 ppm Se, but sows fed the organic Se source had a greater transfer of Se to the neonate, colostrum, milk, weaned pig, and sow tissues than sows fed inorganic Se.

Animal Feed↗

Effects of diet complexity and dietary lactose levels during three starter phases on postweaning pig performance.

Four experiments involving 1,005 crossbred pigs weaned at 19 +/- 2 d of age evaluated the effect of diet complexity and lactose level on starter pig performances. Experiment 1 was a randomized complete block (RCB) conducted in nine replicates with 135 pigs. A complex diet using several protein sources, a semicomplex diet with fewer protein sources, and a simple diet of corn and soybean meal comprised the three treatment groups. All diets contained 25% lactose (as-fed basis) with lysine (total) constant from d 0 to 14 (1.55%) and d 14 to 28 (1.45%), respectively. Gain, feed intake, and feed efficiency (P < 0.05) improved as diet complexity increased during both periods. In Exp. 2, 240 pigs in eight replicates in a RCB design were fed complex diets, but dietary lactose (total; as-fed basis) levels ranged from 10 to 35% in 5% increments from 0 to 14 d after weaning. From 14 to 30 d, a common 17% lactose diet was fed to evaluate the effects of early lactose level on subsequent responses. Gains (P < 0.05) increased for the 0- to 7- and 0- to 14-d periods as lactose increased to 30%. Similar gains resulted for all treatment groups from 14 to 30 d after weaning, with no evidence of compensatory responses to early lactose levels. In Exp. 3, 330 pigs were fed complex diets. From 0 to 7 d after weaning, the diets contained 25% lactose (as-fed basis), and from 7 to 21 d postweaning, the lactose levels ranged from 7 to 31% in 5% increments. Gain (P < 0.01) and feed efficiency (P < 0.05) increased from 7 to 21 d to the 17% lactose level. In Exp. 4, 300 pigs were fed 25 and 17% (as-fed basis) lactose diets from 0 to 7 and 7 to 21 d postweaning, respectively. From 21 to 35 d postweaning, lactose levels of 0 to 20% in 5% increments were added to a corn-soybean meal diet. The experiment was conducted as a RCB design in 12 replicates. Gain (P < 0.05) and feed intake (P < 0.05) increased to 10 to 15% lactose. When the data from Exp. 4 were partitioned into lighter (15.0 kg) and heavier (17.7 kg) pig weight replicates, only the lighter replicates had significant improvements in gain, feed intake, and feed efficiency (P < 0.05) in response to dietary lactose. These results demonstrated that starter pigs performed better when fed complex diets, that dietary lactose levels of 25 to 30% (to 7 kg BW) during the initial week postweaning, 15 to 20% lactose during d 7 to 21 (to 12.5 kg BW), and 10 to 15% lactose during d 21 to 35 postweaning (to 25 kg BW) resulted in maximum performance.

Animal Feed↗

Consumption of a controlled low-fat diet containing olestra for 9 months improves health risk factors in conjunction with weight loss in obese men: the Ole' Study.

OBJECTIVE: To compare the effects of a standard American diet, a traditional low-fat diet, and a low-fat diet containing the fat substitute olestra on risk factors for heart disease and diabetes. DESIGN: A 9-month, double-blind, randomized, parallel-arm, feeding study comparing three diets: (1). control (33% fat), (2). fat-reduced (FR; 25% fat), and (3). fat-substituted (FS) where olestra replaced 1/3 of dietary fat (33% lipid and 25% digestible fat). Subjects were allowed to adjust their total energy intake as desired, allowing weight to fluctuate. SUBJECTS: A total of 37 healthy, obese men (age 36.7+/-1.3 y; body mass index 30.8+/-0.4 kg/m(2)). MEASUREMENTS: Body weight and composition by dual-energy X-ray absorptiometry, blood pressure, serum lipids, lipoproteins, hemostatic factors, glucose, insulin, and leptin at baseline and every 3 months. RESULTS: The FS group lost 6.27 kg of body weight by 9 months vs 4.0 kg in the control and 1.79 kg in the FR groups. There was a significant diet main effect on cholesterol (P=0.002), low-density lipoprotein cholesterol (P=0.003), and triglycerides (P=0.01), all of which decreased in the FS group but not the other groups by 9 months. Apolipoprotein B (ApoB) increased in the FR and control groups but was unchanged in the FS group (diet main effect P=0.04). High-density lipoprotein (HDL) cholesterol increased in all groups over 9 months (time main effect P=0.0001). Time main effects were also observed for cholesterol, ApoA1, ApoB, Factor VII, diastolic blood pressure, and glucose. After adjustment for % fat loss at 9 months, the effects of diet on change in risk factors remained significant only for triglycerides. DISCUSSION: Consumption of a low-fat diet containing olestra for 9 months produced significant improvement in cardiovascular risk factors, an effect largely explained by weight loss. Long-term low-fat diet consumption with or without olestra does not decrease HDL cholesterol.

Adult↗

A role for olestra in body weight management.

Olestra is a fat substitute made from fatty acids esterified to sucrose and can be used in the preparation of virtually any food made with fat. Foods made with olestra retain the mouthfeel, palatability and satiating effects of their full-fat counterparts without providing any digestible energy. Because olestra provides no energy, it has the potential to be a useful tool in weight loss and weight maintenance. Short-term studies of olestra replacement in foods demonstrate that fat replacement leads to a net reduction in fat intake. When excess total energy is available, fat replacement also reduces total energy intake in lean and obese men and women. In longer-term studies in which olestra is incorporated into the daily diet, there is an incomplete compensation for the fat energy replaced by olestra. When overweight men consumed olestra as part of a varied diet over nine months, weight loss continued for the duration of the study, whereas individuals receiving a typical low-fat diet regained most of the initial weight lost. Other studies are underway to examine the usefulness of olestra in long-term weight maintenance following weight loss. Post-marketing surveillance of olestra foods in the United States indicates that substitution of olestra for only 1-2 g of fat d-1 may be sufficient to prevent the average weight gain reported in adults of 0.5-1.0 kg year-1.

Dietary Fats↗

From instinct to intellect: the challenge of maintaining healthy weight in the modern world.

The global obesity epidemic is being driven in large part by a mismatch between our environment and our metabolism. Human physiology developed to function within an environment where high levels of physical activity were needed in daily life and food was inconsistently available. For most of mankind's history, physical activity has 'pulled' appetite so that the primary challenge to the physiological system for body weight control was to obtain sufficient energy intake to prevent negative energy balance and body energy loss. The current environment is characterized by a situation whereby minimal physical activity is required for daily life and food is abundant, inexpensive, high in energy density and widely available. Within this environment, food intake 'pushes' the system, and the challenge to the control system becomes to increase physical activity sufficiently to prevent positive energy balance. There does not appear to be a strong drive to increase physical activity in response to excess energy intake and there appears to be only a weak adaptive increase in resting energy expenditure in response to excess energy intake. In the modern world, the prevailing environment constitutes a constant background pressure that promotes weight gain. We propose that the modern environment has taken body weight control from an instinctual (unconscious) process to one that requires substantial cognitive effort. In the current environment, people who are not devoting substantial conscious effort to managing body weight are probably gaining weight. It is unlikely that we would be able to build the political will to undo our modern lifestyle, to change the environment back to one in which body weight control again becomes instinctual. In order to combat the growing epidemic we should focus our efforts on providing the knowledge, cognitive skills and incentives for controlling body weight and at the same time begin creating a supportive environment to allow better management of body weight.

Biological Evolution↗

Pincer-like amido complexes of platinum, palladium, and nickel.

The ligands bis(8-quinolinyl)amine (BQAH, 1), (2-pyridin-2-yl-ethyl)-(8-quinolinyl)amine (2-pyridin-2-yl-ethyl-QAH, 2), o-dimethylaminophenyl(8-quinolinyl)amine (o-(NMe2)Ph-QAH, 3), and 3,5-dimethylphenyl(8-quinolinyl)amine (3,5-Me2Ph-QAH, 4) have been prepared in high yield from aryl halide and amine precursors by palladium-catalyzed coupling reactions. Deprotonation of 1 with nBuLi in toluene affords the lithium amide complex [Li][BQA] (5), whose dimeric solid-state crystal structure is presented. Lithium amide 5 was transmetalated by TlOTf to afford the thallium(I) amido complex [Tl][BQA] (6). An X-ray structural study of 6 shows it to be a 1:1 complex of the BQA ligand and Tl. Entry into the group 10 chemistry of the parent ligand 1 was effected by both protolytic and metathetical strategies. Thus, the divalent chloride complexes (BQA)PtCl (7), (BQA)PdCl (8), and (BQA)NiCl (9) were prepared and fully characterized. An X-ray structural study for each of these three complexes shows them to be well-defined, square-planar complexes in which the auxiliary BQA ligand binds in a planar, eta(3)-fashion. For comparison, the reactivity of ligands 2-4 with (COD)PtCl2 was studied. While reaction with ligand 2 afforded an ill-defined product mixture, ligands 3 and 4 reacted with (COD)PtCl2 to generate the unusual alkyl complexes (o-(NMe2)Ph-QA)Pt(1,2-eta(2)-6-sigma-cycloocta-1,4-dienyl) (10) and (3,5-Me2Ph-QA)Pt(1,2-eta(2)-6-sigma-cycloocta-1,4-dienyl) (11), both of which have been structurally characterized.

Journal Article↗

Atomic carbon as a terminal ligand: studies of a carbidomolybdenum anion featuring solid-state (13)C NMR data and proton-transfer self-exchange kinetics.

Anion [CMo(N[R]Ar)(3)](-) (R = C(CD(3))(2)CH(3) or (t)Bu, Ar = 3,5-C(6)H(3)Me(2)) containing one-coordinate carbon as a terminal substituent and related molecules have been studied by single-crystal X-ray crystallography, solution and solid-state (13)C NMR spectroscopy, and density functional theory (DFT) calculations. Chemical reactivity patterns for [CMo(N[R]Ar)(3)](-) have been investigated, including the kinetics of proton-transfer self-exchange involving HCMo(N[R]Ar)(3), the carbidomolybdenum anion's conjugate acid. While the Mo triple bond C bond lengths in [K(benzo-15-crown-5)(2)][CMo(N[R]Ar)(3)] and the parent methylidyne, HCMo(N[R]Ar)(3), are statistically identical, the carbide chemical shift of delta 501 ppm is much larger than the delta 282 ppm shift for the methylidyne. Solid-state (13)C NMR studies show the carbide to have a much larger chemical shift anisotropy (CSA, 806 ppm) and smaller (95)Mo--(13)C coupling constant (60 Hz) than the methylidyne (CSA = 447 ppm, (1)J(MoC) = 130 Hz). DFT calculations on model compounds indicate also that there is an increasing MoC overlap population on going from the methylidyne to the terminal carbide. The pK(a) of methylidyne HCMo(N[R]Ar)(3) is approximately 30 in THF solution. Methylidyne HCMo(N[R]Ar)(3) and carbide [CMo(N[R]Ar)(3)](-) undergo extremely rapid proton-transfer self-exchange reactions in THF, with k = 7 x 10(6) M(-1) s(-1). Besides being a strong reducing agent, carbide [CMo(N[R]Ar)(3)](-) reacts as a nucleophile with elemental chalcogens to form carbon-chalcogen bonds and likewise reacts with PCl(3) to furnish a carbon-phosphorus bond.

Journal Article↗

Quantifying and separating the effects of macronutrient composition and non-macronutrients on energy density.

The purpose of the present study was to estimate and compare the effects of macronutrient composition (relative portions of macronutrients) and of non-macronutrient components (e.g. water and fibre) on energy density (energy per unit weight) of the diets of human subjects. We used standard macronutrient energy content values to develop a simple conceptual model and equation for energy density in terms of % energy from dietary fat and % non-macronutrients by weight. To study these effects in self-selected diets of free-living subjects, we used four consecutive days of self-weighed and recorded food records for thirty-two male and thirteen female free-living adult subjects. In the range of typical human diets, the effect of % non-macronutrients by weight was several times greater than that of % energy from dietary fat, both in absolute terms and relative to daily variation in subjects' diets. Both effects were large enough to be physiologically important. Non-macronutrients (% by weight) alone explained much more of the variation in self-selected dietary energy density either between subjects (R2 95 %) or day-to-day (R2 95 %) than did % energy from dietary fat (R2 5 % and 6 % respectively). Omitting beverages gave similar results. The smaller effect of macronutrient composition on energy density of diets is mainly because alterations in macronutrient composition affect only the portion of typical dietary intake that is macronutrients (one-quarter to one-third of weight). Mathematical methods are also useful in analysing observational data and for separating effects of macronutrient composition and non-macronutrients in intervention studies. These results illustrate the importance of considering non-macronutrients in the design and analysis of experimental or observational dietary data.

Adult↗

Changes in diet, weight, and serum lipid levels associated with olestra consumption.

BACKGROUND: Specially manufactured low-fat and nonfat foods have become increasingly available over the past 2 decades and controversy has surrounded the issue of whether these products have beneficial or adverse effects on the health and nutritional status of Americans. METHODS: This study examines the association of olestra consumption with changes in dietary intakes of energy, fat, and cholesterol and changes in weight and serum lipid concentrations. Data are from a cohort of 335 participants in the Olestra Post-Marketing Surveillance Study sentinel site in Marion County (Indianapolis, Ind). Diet, weight, and serum lipid levels were assessed before the market release of olestra and 1 year later, after olestra-containing foods were widely available. Olestra intake at the 1-year follow-up was categorized as none, low (>0 to 0.4 g/d), moderate (0.4 to 2.0 g/d), and heavy (>2.0 g/d). RESULTS: Participants in the heavy olestra consumption category significantly reduced dietary intake of percentage of energy from fat (2.7 percentage points, P for trend,.003) and saturated fat (1.1 percentage points, P for trend,.02). Consumers in the highest category of olestra consumption had statistically significantly reduced total serum cholesterol levels of -0.54 mmol/L (-21 mg/dL)compared with -0.14 mmol/L (-5 mg/dL) among olestra nonconsumers (P for trend,.03). CONCLUSIONS: These results indicate that introduction of a new fat substitute (olestra) in the US market was associated with healthful changes in dietary fat intake and serum cholesterol concentrations among consumers who chose to consume olestra-containing foods.

Anticholesteremic Agents↗

Effects of aerobic fitness on fat oxidation and body fatness.

OBJECTIVE: This study investigated the contributions of physical fitness and body composition to 24-h fat oxidation in adults under sedentary conditions in a whole-room calorimeter. METHODS: The following measurements were studied in 109 adults (49 male/45 female) at least 36 h after a bout of exercise: 1) aerobic fitness level assessed by VO2max, 2) body composition determined by underwater weighing, 3) resting metabolic rate (RMR) after an overnight fast, and 4) 24-h energy expenditure (EE) and substrate oxidation determined in a whole-room calorimeter. While in the calorimeter, subjects were provided with a diet (15% protein, 30% fat, and 55% carbohydrate) estimated to produce energy balance on a sedentary day and of similar nutritional composition to their daily dietary intake. RESULTS: We found strong negative correlations between VO2max and % body fat in both male and female subjects, but no relationship between VO2max and 24-h EE under the sedentary conditions of this study. In male subjects, VO2max (mL O2 x kg(-1) fat-free mass x min(-1)) was negatively related to fat oxidation (r = -0.397, P < 0.005), and fat oxidation was more closely related to fat mass (r = 0.434, P < 0.0002) than to fat-free mass (r = 0.165, NS). In contrast, none of these relationships were significant in females. CONCLUSION: The results show that in male subjects under sedentary conditions, 24-h fat oxidation is positively related to body fat mass and negatively related to VO2max (the marker used here for level of physical fitness). This supports our hypothesis that regularly active males maintain lower body fat stores as the low contribution to daily fat oxidation from a lower body fat mass is counterbalanced by the high contribution to fat oxidation from daily physical activity. The lack of a relationship between VO2max and 24-h EE under the sedentary conditions of this study suggests that the major effects of physical activity on total daily EE and fat oxidation may occur during and relatively quickly after an exercise bout. Further, these data also suggest that cessation of regular exercise will likely be associated with a high risk of positive fat balance and weight gain.

Adipose Tissue↗

Assessment of phylloquinone and dihydrophylloquinone dietary intakes among a nationally representative sample of US consumers using 14-day food diaries.

OBJECTIVE: To estimate dietary intakes of phylloquinone and dihydrophylloquinone in a representative sample of the American population using 14-day food diaries. DESIGN: Vitamin K food composition data were applied to 14-day food diaries completed by a nationally representative sample of approximately 2,000 households that participated in a Market Research Corporation of America menu census survey between July 1991 and June 1992. Dietary intakes were estimated for phylloquinone and dihydrophylloquinone. SUBJECTS: Subjects were 4,741 men, women and children with demographic characteristics similar to those of the US census population. STATISTICAL ANALYSIS PERFORMED: Descriptive statistics and 2-sample t tests. RESULTS: Mean reported intakes of phylloquinone among adults increased with age. Men and women in the 18- to 44-year-old groups reported mean phylloquinone intakes below the current Recommended Dietary Allowance for vitamin K. Of all study participants, 99.3% reported consumption of dihydrophylloquinone during the 14 days of diet recording; reported intakes peaked before the age of 6 years; after the age of 6 years intakes were constant. APPLICATIONS: The Market Research Corporation of America data provide a reference range for dietary intakes of 2 forms of vitamin K in the US diet: phylloquinone and dihydrophylloquinone. Given the putative role of vitamin K in bone mineralization, low intakes of phylloquinone reported among young adults highlight the need to educate the US population about the requirement for and sources of vitamin K. The abundance of dihydrophylloquinone in the US diet suggests the need for study of its biological activity relative to phylloquinone.

Adolescent↗

Dietary carotenoids and lung cancer: a review of recent research.

Several hundred carotenoid research studies have been published since 1996, when two major intervention trials showed a lack of protective effect of beta-carotene supplements against lung cancer. Recent epidemiologic studies continue to show an association between high dietary intake of beta-carotene and lower risk of lung cancer. New research is attempting to clarify the apparently contradictory results of intervention and epidemiologic studies. Promising areas of investigation include characterizing biologic activities of carotenoids and gaining further insight into whether they may serve primarily as markers for a healthy lifestyle or diet.

Animals↗

Dietary carotenoids and certain cancers, heart disease, and age-related macular degeneration: a review of recent research.

Key epidemiologic studies show associations between high dietary intakes of certain carotenoid-containing fruits and vegetables and reduced risk of prostate cancer, breast cancer, head and neck cancers, cardiovascular disease, and age-related macular degeneration, although overall the evidence is inconsistent. Little is known about the potential biochemical mechanisms whereby carotenoids might protect against disease, and human intervention trials are limited to high dose beta-carotene, which is not protective against lung cancer or cardiovascular disease. Authoritative scientific organizations continue to emphasize increased consumption of fruits and vegetables but do not make specific recommendations for carotenoids because of a lack of data that directly link them to disease reduction.

Breast Neoplasms↗

Isolation and characterization of Bordetella bronchiseptica from cats in southern Louisiana.

The role of Bordetella bronchiseptica in respiratory disease of domestic cats is currently being explored. Clinical and experimental studies in the United Kingdom have shown Bordetella bronchiseptica to be a primary respiratory pathogen in cats; similar studies in the United States are limited. The purpose of this study is to report on the isolation, seroprevalence, and partial characterization of Bordetella bronchiseptica from shelter cats in southern Louisiana. A total of 614 cats from four local shelters were studied. All cats appeared to be asymptomatic for signs of respiratory disease. Bordetella bronchiseptica was isolated in 19/614 (3.1%) cats by oropharyngeal swab and in 6/614 cats by bronchial lavage. Using an antibody capture ELISA method, 148/614 (24.1%) cats were seropositive for Bordetella bronchiseptica. The 25 isolates of Bordetella bronchiseptica were further characterized by ribotype analysis, and a total of 17 different ribotypes were identified. Specific pathogen-free kittens were experimentally infected with five of the isolates, and four of the five isolates induced clinical signs typical of feline bordetellosis. It is concluded that Bordetella bronchiseptica is present in the cat population in southern Louisiana, the organism can be isolated from asymptomatic cats, some of these isolates can produce disease in specific pathogen-free kittens, and that Bordetella bronchiseptica isolates from cats in a relatively small geographic area are genetically diverse. This and other studies indicate that Bordetella bronchiseptica should be considered in cases of feline respiratory disease.

Animal Husbandry↗

Environmental contributions to the obesity epidemic.

The current epidemic of obesity is caused largely by an environment that promotes excessive food intake and discourages physical activity. Although humans have evolved excellent physiological mechanisms to defend against body weight loss, they have only weak physiological mechanisms to defend against body weight gain when food is abundant. Control of portion size, consumption of a diet low in fat and energy density, and regular physical activity are behaviors that protect against obesity, but it is becoming difficult to adopt and maintain these behaviors in the current environment. Because obesity is difficult to treat, public health efforts need to be directed toward prevention.

Animals↗

Effects of 14 d of covert substitution of olestra for conventional fat on spontaneous food intake.

We conducted a double-blind, placebo-controlled, within-subject crossover study to investigate the effects of covert substitution of olestra, a non-energy-containing fat replacer, for conventional fat on food selection and energy intake in lean and obese men and women. Fifty-one subjects [BMI (kg/m2): 19-36; age: 25-63 y] were studied during two 14-d treatment periods (olestra and placebo), with a 7-d washout between feeding periods. During the intervention periods all foods were provided to the subjects. The aim was to produce a 10% dilution of total energy intake by replacing conventional triacylglycerol with olestra. To accomplish this, subjects were required to consume core foods providing 20-35 g olestra (depending on estimated energy needs) or the same foods containing placebo triacylglycerol. Additional items could be selected from foods that varied in macronutrient composition. When the two treatment periods were compared, total energy intake was 8% lower and fat intake 11% lower during the olestra period than during the placebo treatment period (P < 0.0001). Overall, subjects compensated for 15% of the fat and 20% of the total energy replaced by olestra. In absolute terms, subjects consumed 32% of total energy from fat during the placebo period and 27% of total energy from fat during the olestra period. Neither carbohydrate nor protein intake (g/d) differed between periods. The results did not differ as a function of BMI (lean compared with obese) or sex. Over a 2-wk period, covert substitution of olestra for conventional fat led to reductions in dietary fat intake and total energy intake in all subjects.

Adult↗