Polybrominated dibenzo-p-dioxins,dibenzofurans, and diphenyl ethers in Japanese human adipose tissue

Human adipose samples collected in Tokyo, Japan in 1970 and 2000 were analyzed for the presence of polybrominated dibenzo-p-dioxins (PBDDs), dibenzofurans (PBDFs), and diphenyl ethers (PBDEs), and the concentrations in the two groups were compared. As far as we know, the concentrations of the PBDD/Fs in adipose tissue from the general Japanese population are reported for the first time. Three PBDD/F congeners were found in the following adipose tissues: 2,3,7,8-TeBDD, 2,3,7,8-TeBDF, and 2,3,4,7,8-PeBDF. The median concentrations (ranges) of three PBDD/Fs in 1970 and 2000 were 5.1 (3.4-8.3) and 3.4 (1.9-5.3) pg/g lipid wt (l.w.), respectively. For PBDEs, seven PBDE congeners were determined in the following samples: 2,4,4'-tribromodiphenyl ether (BDE-28), 2,2',4,4'-tetrabromodiphenyl ether (BDE-47), 2,2',4,4',5-pentabromodiphenyl ether (BDE-99), 2,2',4,4',6-pentabromodiphenyl ether (BDE-100), 2,2',4,4',5,5'-hexabromodiphenyl ether (BDE-153), 2,2',4,4',5',6-hexabromodiphenyl ether (BDE-154), and 2,2',3,4,4',5',6-heptabromodiphenyl ether (BDE-183). Median concentrations (ranges) of PBDEs showed a significant increase from 29.2 (6.8-78.4) pg/g l.w. in 1970 to 1288 (466-2,753) pg/g l.w. in 2000. BDE-47, the major congener of PBDEs, was 56.2% and 35.6% of the total in 1970 and 2000, respectively, whereas the BDE-153 was < 1% and 29.7% of the total in 1970 and 2000, respectively. This may indicate that the source of PBDEs had changed during this period. Further analysis of archived human samples from 1970 to 2000 is needed to describe the details of the contamination trends of PBDD/Fs and PBDEs in the Japanese population. Furthermore, PBDD/F monitoring, particularly 2,3,7,8-TeBDD and 2,3,7,8-TeBDF, may give more toxicological information based on TeCDD toxic equivalents (TEQs).     

黄伞多糖的研究进展

黄伞多糖具有调节机体免疫力、抗肿瘤、降血脂、抗菌、抗氧化、抗衰老等多方面的生物活性,是目前最具开发潜力的食药用真菌多糖。该文对黄伞多糖的来源、菌丝体发酵工艺优化、多糖提取工艺优化、分离提取方法、纯化和组成鉴定、生物学活性进行了综述,以期对黄伞多糖未来的研究提供理论基础。     

多脂鳞伞紫外线诱变育种

该研究用已经选育出来的多脂鳞伞菌株作为出发菌株,利用紫外线对其孢子悬液进行诱变处理。结果表明,在紫外线照射65秒的情况下,得到一株正突变菌株（UV-65）,经过斜面培养和发酵实验证实,其菌丝生长比出发菌株旺盛、菌丝产量提高20%;经过6代的连续传代培养,其遗传性状较为稳定。     

Ultrasonic estimation of solid/liquid ratios in fats,oils and adipose tissue

Data are presented for the speed of transmission of pulses of 2.5 MHz ultrasound through fats and oils at temperatures in the range ?50 to +110°C. It is suggested that a measurement of the speed of ultrasound (V), which is greater in solid fats (V_s) than in oils (V_L), might be used to provide an estimate of the proportion of solid in a partially solidified fat. An acoustic parameter ? is defined such that: and it is suggested that ? might be used as a practical index for determination of the volume fraction of solid fat. This procedure might be useful under conditions unsuited to the established methods of dilatometry, calorimetry or nuclear magnetic resonance. As an example of a possible application, measurements are presented for the speed of ultrasound in pig adipose tissues selected to show a range of consistencies which, by subjective assessment and by penetrometer measurements, ranged from ‘soft’, and therefore unsuited for the manufacture of bacon, to ‘hard’. After allowing for the contribution of the fat-free tissue, it was estimated that the lipid in the tissues ranged from about 20 to 88% (by volume) solid. The variation in ? explained 88% of the variance in the penetrometer measurements.     

Differential scanning calorimetry of porcine adipose tissues

Differential scanning calorimetry (DSC) was used for the direct analysis of melting properties in porcine subcutaneous, intermuscular, and kidney leaf adipose tissue by heating at a constant ratio of +5 °C/min from 4 to 90 °C. Melting curves for adipose tissues as well as fat extracted from the associated tissues by chloroform–methanol were generated using DSC. Major peaks in DSC curves were similar among types of adipose tissue but the temperatures of the melting peak and conclusion point differed among types of adipose tissues. From the visual appearance of fat samples it appeared that the major DSC peak corresponded to phase transition of the fat. The direct DSC analysis of porcine adipose tissues may be useful to determine melting properties.     

Prepartum nutrition alters fatty acid composition in plasma, adipose tissue, and liver lipids of periparturient dairy cows

The fatty acyl profile of phospholipids (PL) determines the fluidity of cell membranes and affects cell function. The degree to which long-chain fatty acid (LCFA) composition of PL and triacylglycerols (TG) in liver and total lipids in adipose tissue can be altered by prepartum nutrition in peripartal dairy cows is unclear. Multiparous Holsteins (n = 25) were assigned to 1 of 4 prepartal diets: 1) CA, the control diet fed to meet 120% of energy requirements; 2) CR, a control diet fed to meet 80% of requirements; 3) S, a diet supplemented with mostly saturated free fatty acids (47% 16:0, 36% 18:0, 14% cis-18:1) and fed to meet 120% of requirements; or 4) U, a diet similar to S except that cows were abomasally infused with soybean oil so that the diet plus infused fat would meet 120% of requirements. Diets were fed for 40 d prepartum; all cows received a lactation diet postpartum. Groups CR and U had lower prepartum intakes of dry matter and net energy, but glucose concentrations in plasma were similar among treatments. Cows fed S, U, or CR had greater nonesterified fatty acids in plasma prepartum, but cows fed U had decreased β-hydroxybutyrate postpartum. Postpartal concentrations of total lipids and glycogen in liver tissue were similar among treatments. Cows in group U had a greater percentage of 18:2 but less 16:0, 18:0, and 20:4 in plasma total lipids than cows fed S. Treatment U increased 18:2 and 18:3 and decreased 18:1 in subcutaneous adipose tissue at 1 d postpartum. Across diets, percentages of 16:0 and trans-18:1 were increased, and 18:0, 20:3, and 20:5 were decreased, in hepatic PL at d 1 postpartum. Significant treatment × time interactions indicated that treatment U increased 18:2 in hepatic PL at the expense of 18:1, 20:3, 20:4, 22:6, and 24:0 on d 1 postpartum, but changes were normalized by d 65 postpartum. The unsaturation index of hepatic PL was lower at d 1 than at d −45 or 65, which implies that hepatic membrane fluidity decreased around parturition. The unsaturation index at d 1 was greater for cows fed S than those fed CA or U. Percentages of 16:0, 18:1, and 22:0 were increased, and 18:0, 20:3, 20:4, 20:5, 24:0, and 26:0 were decreased, in hepatic TG at d 1. Prepartal feed restriction modestly affected tissue LCFA profiles. The LCFA profile of adipose tissue, liver PL, and liver TG can be altered by dietary LCFA supply prepartum; changes in liver are normalized by 65 d postpartum.     

Nutrition during mid to late gestation affects growth,adipose tissue deposition,and tenderness in cross-bred beef steers

The objective of this study was to examine whether the plane of nutrition of cows at a critical time for fetal skeletal muscle and adipose tissue development would affect meat quality and carcass composition of offspring. To alter maternal nutrition, beef cows were placed on improved pasture (IP) or native range (NR) pasture from 120 to 150 through 180 to 210 days of gestation. Esophageal extrusa samples collected from cows grazing IP varied from 11.1% crude protein of organic matter early in the test period to 6.0% crude protein of organic matter at the end of the grazing period; whereas, extrusa samples of cows grazing NR ranged from 6.5% crude protein of organic matter during early grazing to 5.4% crude protein of organic matter at the end of the grazing period. Steers were slaughtered and carcass characteristics were collected. Warner–Bratzler shear force was performed on longissumus steaks, western blotting was used to measure proteolysis, and myosin isoform typing was performed. Improved pasture steers had heavier live and hot carcass weights. Tenderness was greater in IP compared to NR steers. No difference in calpastatin content and troponin-T degradation was observed between treatments. The 12th rib fat thickness was greater for IP than for NR steers. Subcutaneous adipose tissue of IP steers tended to have a greater number of cells per field of view than NR steers. Data show improving nutritional status of cows during mid to late gestation affects tenderness, adipose tissue deposition and growth in steers.     

Detection of 2-alkylcyclobutanones,markers for irradiated foods,in adipose tissues of animals fed with these substances

Laboratory rats received a freshly prepared drinking fluid containing 0.005% 2-tetradecyl- or 2-tetradecenyl-cyclobutanones daily for 4 months. These two compounds were recovered in the adipose tissues of the animals that consumed them. Less than 1% of the 2-alkylcyclobutanones ingested daily were excreted in the feces. In addition, our data indicate that 2-alkylcyclobutanones are able to cross the intestinal barrier, to enter into the bloodstream, and to be stored in the adipose tissue of an animal. However, the amounts of these substances detected in the adipose tissues and in the feces were much smaller than the amounts ingested.     

Effects of age, milk replacer composition, and rumen function on lipogenesis in adipose tissue of young calves

Rates of utilization of glucose, acetate, and lactate and activities of selected enzymes were determined in vitro to evaluate the effects of age and diet on lipogenesis in perirenal adipose tissue of calves. Three-day-old Holstein bull calves were fed up to 12 wk of age on one of three dietary treatments: a high carbohydrate milk replacer; a high fat milk replacer; and weaning at 6 wk of age from high fat replacer to calf starter. Adipose tissue biopsies were obtained from calves at 2, 5, 8, and 12 wk of age. Rates of fatty acid synthesis and activities of enzymes of the pentose phosphate and citrate cleavage pathways were increased in calves fed high carbohydrate milk replacer. These parameters were decreased in calves fed high fat replacer and were further depressed after weaning. Substrate preference for fatty acid synthesis in all calves was acetate, then lactate, then glucose. With increase in age from 2 to 12 wk, adipose tissue of calves fed milk replacer partitioned more acetate and lactate toward fatty acid synthesis and less toward oxidation. The pentose phosphate cycle was characterized by high rate of recycling and contributed at least 50% of reducing equivalents required for fatty acid synthesis. It appeared that several features of lipogenesis characteristic of functional ruminants are also shared by preruminant calves.     

Effect of somatotropin, insulin, and glucocorticoid on lipolysis in chronic cultures of adipose tissue from lactating cows

In vitro effects of bovine somatotropin (bST) and insulin plus dexamethasone on lipolysis were evaluated using chronic cultures (48 h) of adipose tissue from lactating cows. Treatments were control (culture medium alone), bST (100 ng/ml), insulin (100 ng/ml) plus dexamethasome (10 nM), and insulin plus dexamethasone plus bST. Following the 48-h cultures, rates of lipolysis were measured in 3-h incubations with isoproterenol (10 microM), adenosine deaminase (0.75 U/ml), and various concentrations of a nonhydrolyzable adenosine analog. The addition of bST to cultures did not alter basal or isoproterenol-stimulated lipolysis. However, the ability of adenosine to inhibit rates of lipolysis was reduced by bST. When measured in the presence of maximal concentrations of adenosine analog, isoproterenol caused an increase in lipolysis above basal, which was twofold greater for explants cultured with insulin plus dexamethasone plus bST than for explants cultured with insulin plus dexamethasone. Dose-response curves for adenosine inhibition of isoproterenol-stimulated lipolysis demonstrated that chronic culture with bST decreased adipose tissue responsiveness and sensitivity to adenosine. Overall, results demonstrated that an in vitro chronic culture system can be used to examine factors that regulate lipolysis. The addition of insulin plus dexamethasone to chronic cultures better maintained the intracellular signaling system, including sensitivity and responsiveness to adenosine inhibition of lipolysis. Results also confirm that bST alters the antilipolytic response to adenosine. Thus, bST effects are in large part due to a relief in the tonic inhibition of lipolysis via changes in the inhibitory G-protein signaling system.     

Characterisation of intramuscular, intermuscular and subcutaneous adipose tissues in yearling bulls of different genetic groups

Fatty acid (FA) composition of intramuscular (IM, Longissimus thoracis muscle), intermuscular (IT) and subcutaneous (SC) fat of one hundred intensively fed yearling bulls with different propensities to fatten were studied. Meat samples were collected from Asturiana de los Valles bulls with different genotypes with respect to the myostatin gene (mh/mh n = 24, mh/+ n = 26 and +/+ n = 25) and from Asturiana de la Montaña (n = 25) bulls lacking the mutation responsible for double muscling and characterised by small to medium-frame size adapted to less favoured mountain areas. FA profiles were expressed as percentages of total FA (g/100 g of total FA) and organised into groups (saturated (SFA), branched (BFA), monounsaturated (MUFA), C18:1trans, polyunsaturated (PUFA), n − 6, n − 3, conjugated linoleic acids (CLA), unsaturated (UFA)) and ratios (MUFA/SFA (M/S), PUFA/SFA (P/S), UFA/SFA (U/S), n − 6/n − 3).

The IT depot was the most saturated and SC depot contained the most monounsaturated FAs, while IM fat had the most polyunsaturated FAs. IM fat showed the highest P/S ratio and for the n − 6/n − 3 ratio there were no significant differences between adipose tissue depots.

In general, genotype effects were more pronounced in IM and SC fat profiles compared to the IT depot, for which no significant differences between genotypes were found in SFA, PUFA (including n − 6 and n − 3), UFA and most of the ratios. IM fat of mh/mh animals had the highest content of PUFA and thus the highest P/S ratio. Accordingly, the presence of the gene causing double muscling influenced the tendency to deposit carcass fat and its FA composition, mainly in IM fat. In general, when carcass fat decreased, SFA content decreased while PUFA and UFA contents increased due to the changes in their percentages.     

Lipids in muscles and adipose tissues, changes during processing and sensory properties of meat products

Dry-cured meat products represent a large part of the meat products on the European market. The technologies develop for these products lead to the production of a large scale of meat products with typical sensory traits. Numerous studies have been devoted to optimise the quality traits of these products which are considered as traditional products by the consumer and provide a high added value to the producer. Among the components of the raw material, lipids play a key role in the final quality of these products. Many sensory traits of dry-cured meat products depend on lipid traits of muscle and adipose tissues of fresh meat and on their degradation through a complex set of lipolytic and oxidative reactions during processing. Lipid traits of both muscle and adipose tissues of fresh meat are strongly related to pig rearing conditions, mainly genotype and feeding strategy. During processing, lipids undergo intense lipid hydrolysis controlled by both lipases and phospholipases, which remain active all along the process. Lipids are also subjected to oxidation, which generates numerous volatile compounds. These volatiles contribute to some typical aroma notes of dry-cured meat products such as rancid, aged ham and dry-cured odours. This paper reviews the recent knowledge on the influence of lipid traits of fresh meat, lipid hydrolysis and oxidation on the development of sensory traits of dry-cured meat products.     

Influence of triglycerides and free fatty acids in milk replacers on calf performance, blood plasma, and adipose lipids

In a 4-wk study of 48 3-day-old calves we compared effects of feeding various fats or their free fatty acids in skim milk-powder based milk replacer, on calf performance, feed utilization, and blood plasma and adipose lipids. When fat was fed, calf performance and feed utilization were equivalent for tallow and coconut oil diets but markedly poorer for corn oil. Complete replacement (tallow) or one-half replacement (coconut and corn oils) of the fats with their free fatty acids reduced calf gains and feed efficiency. Tallow free fatty acids gave lower digestibilities of palmitic and stearic acid and reduced calcium absorption. Free fatty acids from both coconut and corn oils reduced diet palatability and intake; those from tallow and coconut oil markedly interfered (in vitro) with rennet clotting of milk replacers. The main lipid classes in blood plasma for all treatments were cholesteryl esters and phosphatidylcholine. High concentrations (56 to 87%) of linoleic acid occurred in cholesteryl esters for all diets despite low concentrations of linoleic acid in the tallow and coconut oil diets.     

Autofluorescence of adipose tissue measured with fibre optics

The optical absorbance and fluorescence of porcine subcutaneous adipose tissue were measured directly with fibre optics. Either mercury or xenon light sources were used to illuminate tissue samples through one branch of a bifurcated light guide. Fluorescence was detected through the other branch of the light guide. Grating, prism and continuous interference filter monochromators were installed at appropriate locations in the light path and measurements were made with a computer-operated photomultiplier whose dynamic range was optimized at each wavelength measured. There was a small absorbance peak at 420 nm. With excitation at 365 nm, the peak of the fluorescence emission spectrum was at 510 nm with a secondary plateau from 430 to 450 nm. Proline powder and purified biochemical Type III collagen were also autofluorescent with a peak emission at 510 nm. Adipose cells associated with bovine heart valves were examined by fluorescence microscopy to obtain preparations containing adipose cells plus all three histological types of connective tissue fibres on the same section. Reticular fibres (around adipose cells) together with collagen and elastin fibres (in the heart valves) were all autofluorescent. It is suggested that the major source of adipose tissue fluorescence is from the reticular fibres that surround adipose cells, with minor contributions from other sources such as collagenous septa, vascular elastin and, possibly, cytoplasmic components.