Interaction between dietary protein and fat in triglyceride metabolism in the rat: Effects of soy protein and menhaden oil

The objective of the present study was to determine the mechanisms by which dietary proteins interact with dietary lipids in the regulation of triglyceridemia in rats. Male Sprague-Dawley rats (n=56) were subjected to 28-d experimental diets containing different combinations of proteins (20% w/w) and lipid sources (14% w/w): (i) casein-menhaden oil, (ii) casein-beef tallow, (iii) soy protein-menhaden oil, and (iv) soy protein-beef tallow. Significant protein-lipid interactions were observed on triglyceridemia and hepatic cholesterol in fasted rats. The combination of casein and beef tallow was associated with high plasma TG and hepatic cholesterol concentrations, which were reduced by substitution either of soy for casein or of menhaden oil for beef tallow. Therefore, triglyceridemia and liver cholesterol remained low with soy protein feeding, independently of the lipid source, as well as with menhaden oil feeding, regardless of the protein source. The menhaden oil diets reduced plasma cholesterol, hepatic TG, and TG secretion compared with beef tallow diets independently of the dietary protein source. Modifying the source of dietary proteins and lipids had no effect on post-heparin plasma lipoprotein lipase activity. These results demonstrate that soy protein can lower rat triglyceridemia relative to casein when associated with beef tallow consumption, whereas menhaden oil can attenuate hypertriglyceridemia when rats are fed casein. The data further suggest that part of the hypotriglyceridemic effect of soy protein in the rat may be mediated by reduced hepatic lipid synthesis, as is the case for menhaden oil.     

Influence of dietary long-chain PUFA on premature baboon lung FA and dipalmitoyl PC composition

One of the major survival challenges of premature birth is production of lung surfactant. The lipid component of surfactant, dipalmitoyl PC (DPPC), increases in concentration in the period before normal term birth via a net shift in FA composition away from unsaturates. We investigated the influence of dietary DHA and arachidonic acid (AA) on lung FA composition and DPPC concentration in term and preterm baboons. Pregnant animals/neonates were randomized to one of four groups: breast-fed (B), term formula-fed (T⁻), preterm formulafed (P⁻), and preterm fed formula supplemented with DHA-AA (P⁺). Breast milk contained 0.68%wt DHA and the P⁺ group formula contained 0.61%wt DHA. In the preterm groups (P⁻ and P⁺), pregnant females received a course of antenatal corticosteroids. At the adjusted age of 4 wk, neonate lung tissue was harvested, and FA composition and DPPC were analyzed. Palmitate was ∼28%wt of lung total FA and no significant differences were found among the four treatment groups. In contrast, DPPC in the B group lung tissue was significantly greater than DPPC in the unsupplemented groups, but not compared with the P⁺ group. The B and P⁺ groups were not significantly different in DHA and AA, but were different compared with the unsupplemented (T, P⁻) groups. These results indicate that LCP supplementation increases lung DHA and AA, without compromising overall lung 16∶0 or DPPC. The shift in FA composition toward greater unsaturation in the groups consuming LCP supported improved surfactant lipid concentration in preterm neonate lungs.     

Theoretical analysis on bending behavior of functionally graded composite beam crack-controlled by ultrahigh toughness cementitious composites

Ultrahigh toughness cementitious composites (UHTCC) obviously show strain hardening property under tensile or bending loading. The failure pattern of the UHTCC components exhibits multiple fine cracks under uniaxial tensile loading with prominent tensile strain capacity in excess of 3%, with merely 60 μm average crack width even corresponding to the ultimate tensile strain state. The approach adopted is based on the concept of functionally-graded concrete, where part of the concrete, which surrounds the main longitudinal reinforcement in a RC (reinforced concrete) member, is strategically replaced with UHTCC with excellent crack-controlling ability. Investigations on bending behavior of functionally-graded composite beam crack controlled by UHTCC has been carried out, including theo- retical analysis, experimental research on long composite beams without web reinforcement, validation and comparison between experimental and theoretical results, and analysis on crack control. In addition to improving bearing capacity, the results indicate that functionally-graded composite beams using UHTCC has been found to be very effective in preventing corrosion-induced damage compared with RC beams. Therefore, durability and service life of the structure could be enhanced. This paper discusses the development of internal force and crack propagation during loading process, and presents analysis of the internal force in different stages, moment-curvature relationship from loading to damage and calculation of mid-span deflection and ductility index. In the end, the theoretical formulae have been validated by experimental results.     

The influence of pH on reaction pathways for O2 reduction on the Au(100) face

Oxygen reduction on the Au(100) face was studied by the rotating disk-ring electrode technique in solutions of anions which adsorb strongly on gold (HSO₄⁻/SO₄²⁻ and/or OH⁻) over the entire pH range. The specific adsorption of OH⁻ anions, which is a pH dependent process, is found to play the key role in determining the reaction pathways. In the absence of OH⁻ adsorption, for pHs below 6, the reduction of O₂ begins as a 2e-process. Due to the increase in local pH during O₂ reduction, the reaction pathway turns into a 4e-reduction at a certain potential depending on the pH of the solution. For pHs higher than 6, O₂ reduction begins as a 4e-process in the potential region where specifically adsorbed OH⁻ anions are present.     

Studies of surface and gas reactions in a catalytically stabilized combustor

A numerical investigation of a catalytically stabilized thermal (CST) combustor was conducted for a multichannel catalyst bed, and both the catalyst bed and thermal combustor were simultaneously modeled. The numerical model handled the coupling of the surface and gas reaction in the catalyst bed as well as the gas reaction in the thermal combustor. The behavior of the catalyst bed was investigated at a variety of operating conditions, and location of the flame in the CST combustor was investigated via an analysis of the distribution of CO concentration. Through parametric analyses of the flame position, it was possible to derive a criterion to determine whether the flame is present in the catalyst bed or the thermal combustor for a given inlet condition. The results showed that the maximum inlet temperature at which the flame is located in the thermal combustor increased with increasing inlet velocity.     

Restoration of depressed prostanoid-induced ileal contraction in spontaneously hypertensive rats by dietary fish oil

We have reported that dietary fish oil (FO) rich in n-3 PUFA modulates gut contractility. It was further demonstrated that the gut of spontaneously hypertensive rats (SHR) has a depressed contractility response to prostaglandins (PG) compared with normotensive Wistar-Kyoto (WKY) rats. We investigated whether feeding diets supplemented with n-3 PUFA increased gut contractility and restored the depressed prostanoid response in SHR gut. Thirteen-week-old SHR were fed diets containing fat at 5 g/100 g as coconut oil (CO), lard, canola oil containing 10% (w/w) n-3 FA as alpha-linolenic acid (1 8:3n-3), or FO (as HiDHA, 22:6n-3) for 12 wk. A control WKY group was fed 5 g/100 g CO in the diet. As confirmed, the SHR CO group had a significantly lower gut response to PGE2 and PGF2alpha compared with the WKY CO group. Feeding FO increased the maximal contraction response to acetylcholine in the ileum compared with all diets and in the colon compared with lard, and restored the depressed response to PGE2 and PGF2alpha in the ileum but not the colon of SHR. FO feeding also led to a significant increase in gut total phospholipid n-3 PUFA as DHA (22:6n-3) with lower n-6 PUFA as arachidonic acid (20:4n-6). Canola feeding led to a small increase in ileal EPA (20:5n-3) and DHA and in colonic DHA without affecting contractility. However, there was no change in ileal membrane muscarinic binding properties due to FO feeding. This report confirms that dietary FO increases muscarinic- and eicosanoid receptor-induced contractility in ileum and that the depressed prostanoid response in SHR ileum, but not colon, is restored by tissue incorporation of DHA as the active nutrient.     

Very long chain PUFA in murine testicular triglycerides and cholesterol esters

Very long chain (VLC) PUFA of the n−6 and n−3 series are known to occur in mammalian testis. The aim of this work was to characterize further two testicular lipid classes with VLCPUFA, cholesterol esters (CE) and total triglycerides (TG) in rat and mouse testis. The VLCPUFA predominating in these lipids were a series of n−6 pentaenes and tetraenes with 24 to 32 carbons, including small amounts of odd-chain PUFA, 28∶5n−6 and 24∶5n−6 prevailing in CE and TG, respectively. Most of the VLCPUFA of TG were concentrated in a small fraction of TG, made up by 1-O-alkyl-2,3-DAG. This TG subclass was absent altogether from the TG of sexually immature testis. The TG and the CE with VLCPUFA only occurred in testis of adult fertile animals. The proportion of VLCPUFA in total TG and CE was higher in rodents than in other mammals. In the n−6 PUFA-rich adult mouse testis, the amounts of testicular triacylglycerols decreased significantly after consumption of fish oil for 2 wk. Whereas 18∶2n−6 was significantly reduced, the amounts of 22∶5n−6 and longer n−6 PUFA were less affected in all mamor testicular lipids including PC and PE, where they were unchanged. The 1-O-alkyl-2,3-DAG and their n−6 VLCPUFA were virtually unaffected by the diet. The VLCPUFA-containing molecular species of CE and TG may represent a form of storage of cholesterol and polyenoic FA required to sustain spermatogenesis. Via chain-shortening, VLCPUFA stored in the neutral lipids may serve as precursors of the major C₂₂ PUFA typical of cell membrane glycerophospholipids, protecting testicular cells against shifts in FA composition induced by dietary changes.     

大孔强酸树脂吸附硫脲金

研究了D072大孔强酸性阳离子交换树脂从硫脲[Tu=CS(NH2)2]浸金液中吸附Au(Tu)2+的性能和机理. 结果表明，pH=2.0时，树脂对Au(Tu)2+有优良的吸附性能，金的交换容量为78.95 mg/g (Au/干树脂)，吸附的硫脲金可用乙醇-硫酸水溶液洗脱，洗脱率可达96.5%. D072树脂对Au(Tu)2+的吸附符合Langmuir吸附模型.     

<Emphasis Type="Italic">Penicillium</Emphasis> sp. ZD-Z1 chitosanase immobilized on DEAE cellulose by cross-linking reaction

Chitosanase obtained fromPenicillium sp.ZD-Z1 was immobilized on DEAE cellulose with glutaraldehyde by cross-linking reaction. The optimal conditions of immobilization were as follows: 0.1 g DEAE cellulose was treated with 5 ml 5% glutaraldehyde solution; then 2.3 mg chitosanase was immobilized on the carrier. The optimal temperature and pH was 60 °C and 4.0, and the K _m value was 18.87 g/L. Under optimal conditions, the activity of immobilized enzyme is 1.5 U/g, and the recovery of enzyme activity is 81.3%. After immobilization, the optimal temperature and K _m value increased (from 50 °C to 60 °C, from 2.49 g/L to 18.87 g/L), whereas the optimal pH was reduced (from 5.0 to 4.0). The enzyme activity loss was less than 20% after 10 times batch reaction; the immobilized enzyme showed good operation stability.     

PEAK-INSENSITIVE NON-PARAMETRIC SPECTRUM ESTIMATION

Abstract. We study the problem of non-parametric spectrum estimation of a stationary time series that might contain periodic components. In this case the periodogram ordinates have a significant amplitude at frequencies near the frequencies of the periodic components. These can be regarded as outliers in an asymptotically exponential sample. We develop a non-parametric estimator for the spectral density that is insensitive to these outliers in the frequency domain. This is done by robustifying the usual kernel estimator (smoothed periodogram) by means of M-estimation in the frequency domain. We propose to use data-tapered periodograms, which yield a drastic improvement of the procedure, typically for the contaminated situation. This is both shown theoretically and supported by means of simulation. We show consistency of the resulting estimator in the general case, and asymptotic normality in the special case of a Gaussian time series, whether contamination is present or not. Finally we illustrate the finite sample performance of the estimating procedure by some simulation results and by application to the Canadian lynx trappings data.