Acetone as biomarker for ketosis buildup capability--a study in healthy individuals under combined high fat and starvation diets.

BACKGROUND: Ketogenic diets are high fat and low carbohydrate or very low carbohydrate diets, which render high production of ketones upon consumption known as nutritional ketosis (NK). Ketosis is also produced during fasting periods, which is known as fasting ketosis (FK). Recently, the combinations of NK and FK, as well as NK alone, have been used as resources for weight loss management and treatment of epilepsy. METHODS: A crossover study design was applied to 11 healthy individuals, who maintained moderately sedentary lifestyle, and consumed three types of diet randomly assigned over a three-week period. All participants completed the diets in a randomized and counterbalanced fashion. Each weekly diet protocol included three phases: Phase 1 - A mixed diet with ratio of fat: (carbohydrate + protein) by mass of 0.18 or the equivalence of 29% energy from fat from Day 1 to Day 5. Phase 2- A mixed or a high-fat diet with ratio of fat: (carbohydrate + protein) by mass of approximately 0.18, 1.63, or 3.80 on Day 6 or the equivalence of 29%, 79%, or 90% energy from fat, respectively. Phase 3 - A fasting diet with no calorie intake on Day 7. Caloric intake from diets on Day 1 to Day 6 was equal to each individual's energy expenditure. On Day 7, ketone buildup from FK was measured. RESULTS: A statistically significant effect of Phase 2 (Day 6) diet was found on FK of Day 7, as indicated by repeated analysis of variance (ANOVA), F(2,20) = 6.73, p < 0.0058. Using a Fisher LDS pair-wise comparison, higher significant levels of acetone buildup were found for diets with 79% fat content and 90% fat content vs. 29% fat content (with p = 0.00159**, and 0.04435**, respectively), with no significant difference between diets with 79% fat content and 90% fat content. In addition, independent of the diet, a significantly higher ketone buildup capability of subjects with higher resting energy expenditure (R(2) = 0.92), and lower body mass index (R(2) = 0.71) was observed during FK.

Colorimetric humidity sensor based on liquid composite materials for the monitoring of food and pharmaceuticals.

Using supported ionic-liquid membrane (SILM)-inspired methodologies, we have synthesized, characterized, and developed a humidity sensor by coating a liquid composite material onto a hygroscopic, porous substrate. Similar to pH paper, the sensor responds to the environment's relative humidity and changes color accordingly. The humidity indicator is prepared by casting a few microliters of low-toxicity reagents on a nontoxic substrate. The sensing material is a newly synthesized liquid composite that comprises a hygroscopic medium for environmental humidity capture and a color indicator that translates the humidity level into a distinct color change. Sodium borohydride was used to form a liquid composite medium, and DenimBlu30 dye was used as a redox indicator. The liquid composite medium provides a hygroscopic response to the relative humidity, and DenimBlu30 translates the chemical changes into a visual change from yellow to blue. The borate-redox dye-based humidity sensor was prepared, and then Fourier transform infrared spectroscopy, differential scanning calorimetry, and image analysis methods were used to characterize the chemical composition, optimize synthesis, and gain insight into the sensor reactivity. Test results indicated that this new sensing material can detect relative humidity in the range of 5-100% in an irreversible manner with good reproducibility and high accuracy. The sensor is a low-cost, highly sensitive, easy-to-use humidity indicator. More importantly, it can be easily packaged with products to monitor humidity levels in pharmaceutical and food packaging.

How have researchers studied multiracial populations? A content and methodological review of 20 years of research.

The U.S. Census shows that the racial-ethnic makeup of over 9 million people (2.9% of the total population) who self-identified as multiracial is extremely diverse. Each multiracial subgroup has unique social and political histories that may lead to distinct societal perceptions, economic situations, and health outcomes. Despite the increasing academic and media interest in multiracial individuals, there are methodological and definitional challenges in studying the population, resulting in conflicting representations in the literature. This content and methods review of articles on multiracial populations provides a comprehensive understanding of which multiracial populations have been included in research and how they have been studied, both to recognize emerging research and to identify gaps for guiding future research on this complex but increasingly visible population. We examine 125 U.S.-based peer-reviewed journal articles published over the past 20 years (1990 to 2009) containing 133 separate studies focused on multiracial individuals, primarily from the fields of psychology, sociology, social work, education, and public health. Findings include (a) descriptive data regarding the sampling strategies, methodologies, and demographic characteristics of studies, including which multiracial subgroups are most studied, gender, age range, region of country, and socioeconomic status; (b) major thematic trends in research topics concerning multiracial populations; and (c) implications and recommendations for future studies.

Gold nanoparticle-quantum dot-polystyrene microspheres as fluorescence resonance energy transfer probes for bioassays.

The paper describes the development of highly sensitive particle-based fluorescence resonance energy transfer (FRET) probes that do not use molecular fluorophores as donors and acceptors. In these probes, CdSe/ZnS luminescent quantum dots (QDs) were capped with multiple histidine-containing peptides to increase their aqueous solubility while maintaining their high emission quantum yield and spectral properties. The peptide-modified QDs (QD-His) were covalently attached to carboxyl-modified polystyrene (PS) microspheres to form highly emitting PS microspheres (QD-PS). Gold nanoparticles (AuNPs) were then covalently attached to the QD-PS surface to form AuNP-QD-PS composite microspheres that were used as FRET probes. Attachment of AuNPs to QD-PS completely quenched the QD emission through FRET interactions. The emission of QD-PS was restored when the AuNPs were removed from the surface by thiol ligand displacement. The new AuNP-QD-PS FRET platform is simple to prepare and highly stable, and it opens many new possibilities for carrying out FRET assays on microparticle-based platforms and in microarrays. The versatility of these assays could be greatly increased by replacing the linkers between the QDs and AuNPs with ones that selectively respond to specific cleaving agents or enzymes.

Malnutrition and hemodynamic status in adolescents hospitalized for anorexia nervosa.

OBJECTIVE: To determine the effects of malnutrition on hemodynamic status of adolescents hospitalized for anorexia nervosa. DESIGN: Longitudinal observational study. SETTING: Tertiary care pediatric hospital. Patients Thirty-eight adolescents with anorexia nervosa, aged 13 to 21 years, with a mean (SD) body mass index (calculated as weight in kilograms divided by height in meters squared) of 15.9 (1.8). Intervention Subjects received standard care, including bed rest and graded nutritional therapy. A subsample of subjects (n=19) returned 11 to 57 weeks following hospitalization for a second cardiac evaluation. MAIN OUTCOME MEASURES: Results from a 15-lead electrocardiogram, echocardiogram, treadmill stress test, and spinal bone mineral density measurement. RESULTS: On admission, 26 subjects (68%) had sinus bradycardia. Bradycardia was less common in participants with a longer duration of illness (P=.04). Left ventricle mass was lower than predicted for age (Z score<-1.0) in 11 subjects (31%). Exercise tolerance was normal by all measures. Both heart rate and QT interval were predictors of spinal bone mineral density. In those who returned for follow-up, absolute measures of left ventricle mass did not change (P=.27). However, the corresponding Z scores declined over time (mean [SD] change, -0.9 [1.3]; P=.02). CONCLUSIONS: In acutely malnourished adolescents with anorexia nervosa, few truly pathologic cardiac findings were identified. Sinus bradycardia was observed in most cases. Mild reductions in left ventricle mass and left ventricle function were seen both at baseline and at follow-up, suggesting early sparing of cardiac muscle in the face of moderate malnutrition as well as a relative delay of cardiac muscle restoration. The association of hemodynamic status with altered spinal bone mineral density emphasizes the range of systems affected by malnutrition in anorexia nervosa.

The effect of bed rest on bone turnover in young women hospitalized for anorexia nervosa: a pilot study.

CONTEXT: Malnourished adolescents with anorexia nervosa (AN) requiring medical hospitalization are at high risk for skeletal insults. Even short-term bed rest may further disrupt normal patterns of bone turnover. OBJECTIVE: The objective of the study was to determine the effect of relative immobilization on bone turnover in adolescents hospitalized for AN. DESIGN: This was a short-term observational study. SETTING: The study was conducted at a tertiary care pediatric hospital. STUDY PARTICIPANTS: Twenty-eight adolescents with AN, aged 13-21 yr with a mean body mass index of 15.9 +/- 1.8 kg/m(2), were enrolled prospectively on admission. INTERVENTION: As per standard care, all subjects were placed on bed rest and graded nutritional therapy. MAIN OUTCOME MEASURE: Markers of bone formation (bone specific alkaline phosphatase), turnover (osteocalcin), and bone resorption (urinary N-telopeptides NTx) were measured. RESULTS: During the 5 d of hospitalization, serum osteocalcin increased by 0.24 +/- 0.1 ng/ml . d (P = 0.02). Urine N-telopeptides reached a nadir on d 3, declining -6.9 +/- 2.8 nm bone collagen equivalent per millimole creatinine (P = 0.01) but returned to baseline by d 5 (P > 0.05). Bone-specific alkaline phosphatase exhibited a decline that was strongly age dependent, being highly significant for younger subjects only [age 14 yr: -0.42 +/- 0.11 (P = 0.0002); age 18 yr: -0.03 +/- 0.08 (P = 0.68)]. Age had no effect on other outcome measures. CONCLUSION: Limitation of physical activity during hospitalization for patients with AN is associated with suppressed bone formation and resorption and an imbalance of bone turnover. Future interventional studies involving mechanical stimulation and/or weight-bearing activity are needed to determine whether medical protocols prescribing strict bed rest are appropriate.

Glucose oxidase-magnetite nanoparticle bioconjugate for glucose sensing.

Immobilization of bioactive molecules on the surface of magnetic nanoparticles is of great interest, because the magnetic properties of these bioconjugates promise to greatly improve the delivery and recovery of biomolecules in biomedical applications. Here we present the preparation and functionalization of magnetite (Fe3O4) nanoparticles 20 nm in diameter and the successful covalent conjugation of the enzyme glucose oxidase to the amino-modified nanoparticle surface. Functionalization of the magnetic nanoparticle surface with amino groups greatly increased the amount and activity of the immobilized enzyme compared with immobilization procedures involving physical adsorption. The enzymatic activity of the glucose oxidase-coated magnetic nanoparticles was investigated by monitoring oxygen consumption during the enzymatic oxidation of glucose using a ruthenium phenanthroline fluorescent complex for oxygen sensing. The glucose oxidase-coated magnetite nanoparticles could function as nanometric glucose sensors in glucose solutions of concentrations up to 20 mmol L(-1). Immobilization of glucose oxidase on the nanoparticles also increased the stability of the enzyme. When stored at 4 degrees C the nanoparticle suspensions maintained their bioactivity for up to 3 months.