The effect of resistant starches on fat oxidation in healthy adults as measured by a 13CO2-breath test

A resistant starch (RS) mixture (MIX) consisting of fibre of potatoes (FP) and wrinkled pea starch (WPS), and high amylose maize starch (HAMS) were supplemented in adults to evaluate their effects on fat oxidation by means of a ¹³CO₂-breath test. Sixteen subjects received a regular diet either without or with the supplementation of MIX and HAMS in randomised order. After administration of a [U-¹³C]algal lipid mixture, exhaled air was collected over 14?h in 0.5- and 1-h intervals. The ¹³C abundances were measured by nondispersive infrared spectroscopy. In comparison to the dry run (DR), supplementation with MIX and with HAMS increased the cumulative percentage dose recovery: (DR: 16.7?%, MIX: 16.9?%, HAMS: 18.0?%), but without statistical significance. The colonic degradation of MIX and HAMS to short-chain fatty acids tends to lower the formation of carbohydrate-derived acetyl-CoA and contributes to a postprandial lipid oxidation increase by using fat-derived acetyl-CoA as a compensatory fuel source.     

Metabolite Pools and Metabolic Branching as Factors of in-vivo Isotope Discriminations by Kinetic Isotope Effects

Abstract

Inter- and intra-molecular non-statistical isotope distributions do not only require the existence of a kinetic isotope effect on a defined enzyme catalyzed reaction, but also the prerequisite that this reaction is located at a metabolic branching point. Furthermore a metabolic and isotopic balance demand that the extent of the isotopic shift is reciprocal to the products' yields. On this base the ¹³C-enrichment of L-ascorbic acid in position C-1 and the depletion of glycerol in C-1 are interpreted. The ¹³C-pattern of natural malic acid is discussed as a consequence of isotope effects on the carboxylation of pyruvate and PEP and on the pyruvate dehydrogenase reaction. The patterns of natural products synthezised by transfer of “active acetaldehyde” is proposed to be due to an isotope effect on the thiamine pyrophosphate containing lyase reaction. An isotope effect on the reduction of “active formaldehyde” to “active methyl” and the existence of corresponding pools is responsible for ¹³C-enrichments and depletions of natural products in positions bearing these intermediates. Finally a model for the main nitrogen pools and for isotope discriminations between α-amino, ω-amino-N and amide pools in plants is proposed.     

Compartmental Approach for Evaluation of Plasma Kinetics and 13Co2-Exhalation after Oral Loading with L-[1-13C]Leucine

Abstract

A seven compartment model was applied for evaluation of oral L-[1-¹³C]leucine loading tests (38 μmol/kg body wt.) in healthy volunteers. The model comprises transport and absorption in stomach and gut into a central L-leucine-compartment which is connected to a protein compartment and to the compartment of the corresponding 2-oxo acid. CO₂ release from the latter occurs in a fast and a slow compartment into the central CO₂ compartment for exhalation. Using the fmins routine of MATLAB for parameter estimation, a good agreement was obtained between calculated and actually measured kinetics of ¹³C-labelled metabolites and a mean in vivo L-leucine oxidation of 0.365 ± 0.071 μmol/kg per min (n = 5) was computed. Plausibility of the model was checked by predicting in vivo leucine oxidation rates from primed continuous infusion tests (priming: L-[1-¹³C]leucine, 5 μmol/kg; NaH¹³CO₂, 1.2 μmol/kg; infusion: L-[1-¹³C]leucine, 5 μmol/kg per h). In 5 tested volunteers, the experimental L-leucine oxidation rate amounted to 0.358 ± 0.105 μmol/kg per min versus predicted 0.324±0.099 μmol/kg per min. Possible causes for some observed intraindividual variations are discussed.     

Effect of alcohol consumption on whole-body protein turnover in healthy adults

The aim of the study was to investigate the whole-body protein turnover, either before or after continuous, moderate ethanol-induced oxidative stress by red wine consumption over a relatively short period in healthy volunteers. Ten healthy adults received an individual regular diet over 20 days. After 10 days, the subjects consumed 0.4 ml ethanol kg^?1 day^?1 as red wine together with dinner over a 10-day period. After 8 and 18 days, respectively, a ¹⁵N-labelled yeast protein was administered in a dosage of 4.2 mg kg^?1 body weight. Urine and faeces were collected over 48 h, respectively. The ¹⁵N-enrichment was measured by isotope ratio mass spectrometry, whereas the protein flux rates were calculated by a three-compartment model. The whole-body protein turnover without/with red wine consumption amounted to 3.73±0.6 and 3.49±0.6 g kg^?1 day^?1 (not significant), respectively. Moderate alcohol consumption does not induce significant short-term changes in the whole-body protein turnover of healthy adults.     

Surface Analysis of Inhibitor Film Formed by 4-Amino-N-(1,3-thiazol-2-yl) Benzene Sulfonamide on Carbon Steel Surface in Acidic Media

Inhibitive properties of the antibacterial sulfa drug sulfathiazole—IUPAC name being 4-amino-N-(1,3-thiazol-2-yl) benzene sulfonamide—on the corrosion of carbon steel in 1.0 M HCl solution were investigated using weight loss measurements, electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). Sulfathiazole is a good adsorption inhibitor, and the inhibition efficiency increases with increasing concentration. Adsorption is spontaneous and is best described by Temkin isotherm. XPS analysis showed, at this stage, that the main product of corrosion is a nonstoichiometric Fe³⁺ oxide/oxyhydroxide consisting of a mixture of Fe₂O₃, α, and γ-FeO(OH) and/or Fe(OH)₃, where α, γ-FeO(OH) is the main phase.     

Effects of aging and maternal protein restriction on the muscle fibers morphology and neuromuscular junctions of rats after nutritional recovery

Changes in the nutritional status of mothers may predispose their offspring to neuromuscular disorders in the long term. This study evaluated the effects of maternal protein restriction during pregnancy and lactation on the muscle fibers and neuromuscular junctions (NMJs) of the soleus muscle in the offspring of rats at 365 days of age that had undergone nutritional recovery. Wistar rats were divided into two groups: control (CG) – the offspring of mothers fed a normal protein diet (17%) and restricted (RG) – offspring of mothers fed a low protein diet (6%). After lactation, the male pups received standard chow ad libitum. At 365 days, samples of soleus muscle were collected for muscle fiber analysis (HE staining, NADH-TR reaction and ultrastructure), intramuscular collagen quantification (picrosirius red staining) and NMJs analysis (non-specific esterase technique). The cross-sectional area of type I fibers was reduced by 20% and type IIa fibers by 5% while type IIb fibers increased by 5% in the RG compared to the CG. The percentage of intramuscular collagen was 19% lower in the RG. Disorganization of the myofibrils and Z line was observed, with the presence of clusters of mitochondria in both groups. Regarding the NMJs, in the RG there was a reduction of 10% in the area and 17% in the small diameter and an increase of 7% in the large diameter. The results indicate that the effects of maternal protein restriction on muscle fibers and NMJs seem to be long-lasting and irreversible.     

Kinetic Carbon Isotope Effects in the Decarbonylation of Lactic Acid of Natural Isotopic Composition and of [1-14C] Lactic Acid

Studies of carbon-13 and carbon-14 kinetic isotope effects (K. I. E.) in the decarbonylation of lactic acid (L. A.) in sulphuric acid and in phosphoric acids media have been summarized and compared with earlier studies of ¹⁴C and ¹³C K. I. E. in the decarbonylation of formic and oxalic acids in concentrated sulphuric acid. Supplementary data concerning the decarbonylation of L. A. in sulphuric acid diluted with water and in pyrophosphoric acid are presented and discussed. The observed temperature dependences of ¹³C and ¹⁴C K. I. E. in concentrated H₂SO₄ and in concentrated phosphoric acids media have been rationalized by invoking a change of the mechanism of decarbonylation of L. A. in concentrated sulphuric and phosphoric acids with temperature. Preliminary calculational results concerning ¹³C and ^1??C K. I. E. in decarbonylation processes are also presented. In H₂SO₄ diluted with water and in H₃PO₄ diluted with water the temperature dependence of ¹³C and ¹⁴C K. I. E. is normal and well reproduced by one frequency approximation. In concentrated sulphuric acid and in concentrated phosphoric acids besides the C—OH bond rupture the rupture of a C—C bond had to be considered also to reproduce the observed ¹³C K. I. E. in selected temperature regions.     

The Possible Contribution of Isotope Effects on Ester- and Aldol Condensations to Isotope Discriminations and Isotopic Patterns of Natural Compounds

Abstract

Acetyl-CoA provides the C-2-units for the formation of many secondary compounds. The primary pattern of this intermediate is originating from glucose, further modifications are introduced by isotope effects on the pyruvate-dehydrogenase-reaction and on ester- and aldol-reactions in the course of the biosynthesis of secondary products. The overlap of these various effects is demonstrated through the pattern of some natural products.

The partial pattern of limonene and pulegone, respectively, products from different origin are not identical, this is interpreted as a consequence of individual relative contributions of the above mentioned effects in the plants in question.

On the other hand the distinct relative depletion in a position of sinigrin, a glucosinolate from Brassica nigra, originating from CH₃ of acetate can be assigned to an isotope effect of the aldol reaction between a precursor and acetyl-CoA. An corresponding depletion has been measured in position 5 of citrate. Therefore the kinetic isotope effect on the citrate synthase reaction is studied in vitro at present.     

Preparation of Naturally 13C-Rich Free Fatty Acids (FFA) from Corn Oil and their Application in Metabolic Studies of Lactating Cows

Abstract

When the ¹³C/¹²C ratios in lactose and milk fat of normally fed healthy cows are compared to ¹³C/¹²C in feed a metabolic depletion of ¹³C in the milk constituents becomes obvious.

Due to a carbon isotope effect in the decarboxylation step of pyruvate to Acetyl-Co-A resulting in a ¹³C depleted acetate, depot fat and milk fat are especially reduced in ¹³C relative to ¹²C.

Under pathophysiological conditions after longer fasting periods or in ketosis, long chain fatty acids from depot fat are metabolized and their ¹³C depleted carbon atoms enter the citric acid cycle via Acetyl-Co-A. Then the intermediary products of this cycle become ¹³C depleted too and with a drain on the oxalacetate pool by gluconeogenesis ¹³C depleted carbon atoms are channeled into lactose.

This hypothesis is apt to explain a ¹³C/¹²C decrease in lactose of ketotic cows relative to healthy controls. It is supported by the observation that ¹³C-rich fatty acids from corn oil dosed orally to a ketotic cow increase the ¹³C/¹²C ratios in lactose. So a crossing-over of carbon atoms from long chain fatty acids into glucose and lactose seems highly probable.     

Ultrasound combined with slightly acidic electrolyzed water thawing of mutton: Effects on physicochemical properties,oxidation and structure of myofibrillar protein

The effects of air thawing (AT), water immersion thawing (WT), microwave thawing (MT) and ultrasound combined with slightly acidic electrolyzed water thawing (UST) on the myofibrillar protein (MP) properties (surface hydrophobicity, solubility, turbidity, particle size and zeta potential), protein oxidation (carbonyl content and sulfhydryl content) and structure (primary, secondary and tertiary) of frozen mutton were investigated in comparison with fresh mutton (FM). The solubility and turbidity results showed that the MP properties were significantly improved in the UST treatment. UST treatment could effectively reduce the MP aggregation and enhance the stability, which was similar to the FM. In addition, UST treatment could effectively inhibit protein oxidation during thawing as well. The primary structure of MP was not damaged by the thawing methods. UST treatment could reduce the damage to MP secondary and tertiary structure during the thawing process compared to other thawing methods. Overall, the UST treatment had a positive influence in maintaining the MP properties by inhibiting protein oxidation and protecting protein structure.     

1H and C-13 Nuclear Magnetic Resonance of Tiaprofenic Acid

¹H-NMR spectrum of tiaprofenic acid in CDCI3 was obtained and proton chemical shifts from tetramethylsilane were assigned to each proton and set of equivalent protons of the molecule. The hydroxy proton of the carboxylic acid group was confirmed by deuterium exchange. The natural abundance C-13 nuclear magnetic resonance spectrum of the compound in CDCI3 was recorded using Fourier transorm technique. The chemical shifts of carbon resonances have been assigned on the basis of the chemical shift additivity theory and the signal multiplicity observed in the single frequency off-resonance decoupled (SFORD) spectrum. Also comparison with carbon chemical shifts of model compounds were useful.     

Synthesis and Characterization of Acylated Polycaprolactone (PCL) Nanospheres and Investigation of Their Influence on Aggregation of Amyloid Proteins

Acylated polycaprolactone (PCL) nanospheres were fabricated and employed to interact with amyloid-β-(25–35) peptides (Aβ_25–35), "peptide 11 of the 40 peptide full amyloid-β". The nanospheres were characterized by scanning electron microscopy (SEM), attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, and dynamiclightscattering (DLS), all of which confirmed that the acylated polycaprolactone (Ac-PCL) nanospheres were successfully fabricated. The effect of the nanospheres on the aggregation of Aβ_25–35 peptides was investigated by thioflavin T fluorescence measurements. The result showed that, without nanospheres, the Aβ_25–35 peptides aggregated gradually from monomers and oligomers to long fibrils with increasing incubation time. In comparison, the nanospheres were effective in interfering with fibrillogenesis and aggregation of amyloid-β. We suggest this study may contribute to the development of new therapeutic strategies against amyloid-related disorders.     

Effects of ultrasonic treatment on the structural and functional properties of cactus (Opuntia ficus-indica) seed protein

With the steady increase in the consumption of ultra-processed foods, there is growing interest in sustainable diets that include more plant protein. However, little information is available regarding the structural and functional properties of cactus (Opuntia ficus-indica) seed protein (CSP), a by-product of the cactus seed food-processing chain. This study aimed to explore the composition and nutritional value of CSP and reveal the effects of ultrasound treatment on protein quality. Protein chemical structure analysis showed that an appropriate intensity of ultrasound treatment (450 W) could significantly increase protein solubility (96.46 ± 2.07%) and surface hydrophobicity (13.76 ± 0.85 μg), decrease the content of T-SH (50.25 ± 0.79 μmol/g) and free-SH (8.60 ± 0.30 μmol/g), and enhance emulsification characteristics. Circular dichroism analysis further confirmed that the ultrasonic treatment increased the α-helix and random coil content. Amino acid analysis also suggested that ultrasound treatment (450 W) increased the hydrophobic amino acid content. To evaluate the impact of changes in the chemical structure, its digestion behavior was studied. The results showed that ultrasound treatment increased the release rate of free amino acids. Furthermore, nutritional analysis showed that the digestive products of CSP by ultrasound treatment can significantly enhance the intestinal permeability, increase the expression of ZO-1, Occludin and Claudin-1, thus repairing LPS induced intestinal barrier disfunction. Hence, CSP is a functional protein with high value, and ultrasound treatment is recommended. These findings provide new insights into the comprehensive utilization of cactus fruits.