首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 150 毫秒
1.
G. Ananda Rao  S. Abraham 《Lipids》1983,18(4):335-338
Slices, prepared from the mammary glands of lactating mice, were incubated with either [1-14C]acetate, [U-14C]glucose, or [1-14C]decanoate. From all 3 substrates, radioactivity in the synthesized lipids was found mainly in triacylglycerols (TG). When acetate or glucose served as substrate, decanoate (C10) accounted for 24% of the fatty acids in TG. Hydrolysis of the TG by pancreatic lipase yielded [14C] fatty acids which had relatively more C10 (38%) than did either of the other hydrolysis products mono- or diacylglycerol (14–17%). However, when TG produced by slices from C10 were hydrolyzed, the acid was found to be esterified equally at the C-1, C-2 and C-3 of glycerol. Thus, when fatty acids are synthesized de novo and are converted to TG by gland slices, C10 is predominantly located in the C-3 position, a finding in accord with the situation in milk TG, although such preferential incorporation does not occur when the free acid is presented to the tissue slices.  相似文献   

2.
Gonmori  Kunio  Morita  Tomoaki  Mehendale  Harihara M. 《Lipids》1986,21(3):230-234
The effect of chlorphentermine (CP) treatment (50 mg/kg/ day, per os [po]) on the incorporation of [14C]choline into rat lung phospholipid was studied.Total phospholipid content was increased 2.0-fold and 1.7-fold after seven and 14 days, respectively, compared with the pair-fed rats. The incorporation of [14C]choline into phosphatidylcholine (PC) was significantly inhibited by either seven or 14 days of CP treatment. Nevertheless, the PC content was significantly increased by day 7 and stayed elevated at day 14 of CP treatment. Choline and phosphorylcholine contents were significantly decreased by the CP treatment. These results suggest that the higher accumulation of PC is due to inhibition of enzymes involved in the hydrolysis of phospholipids rather than to a stimulation of the phospholipid synthesis. Presented in part at the SOT Meeting, Atlanta, GA, March 1984 (abstracted inThe Toxicologist 4[1], 64).  相似文献   

3.
Food restriction was found to impair the incorporation of [1-14C]palmitate into myelin membrane lipids of developing rat brain. An attempt was made to determine whether this phenomenon is due to differences in the rate of utilization of the labelled precursor or to its enhanced degradationvia β-oxidative pathways. Undernutrition in pups was imposed by food restriction during gestation and lactation. β-Oxidation by brain region homogenates using [1-14C]palmitate was monitored at days 7, 14 and 21 of postnatal age. There was a significant increase in β-oxidation in the brain regions of undernourished pups, with the cerebrum and cerebellum being more affected than the brain stem. Because developing brain possesses the enzymic potential to utilize ketone bodies, the data may indicate increased usage of palmitate as an energy source in the developing brain of undernourished animals.  相似文献   

4.
We studied the effect of restricting the diet of pregnant and lactating rats on the β-oxidation of fatty acids by the developing heart in suckling pups. Control pregnant rats were fed a stock diet ad libitum. For the experimental group, food was restricted to half of the control intake on the seventh day of pregnancy and continued through lactation. The pups on the restricted diet were significantly smaller than the controls. At postnatal days 5, 14 and 21, the β-oxidation of [1-14C] palmitate by heart homogenates was determined in the presence of ATP, carnitine and CoA. At day 21, the production of14CO2 was 60% lower in the group on the restricted diet. Consequently, the possibility of inhibiting activation or intramitochondrial transport of fatty acids by heart mitochondria was studied in vitro using [1-14C] palmitate, [1-14C] palmitoyl CoA and [1-14C] palmitoyl carnitine. With [1-14C]-palmitate, the rate of14CO2 produced was 2464±317 cpm/mg protein/min for the control and 1682±91 for the restricted diet group. With [1-14C] palmitoyl CoA and [1-14C] palmitoyl carnitine, the oxidation rate of the experimental group was similar to control values, showing clearly that the inhibition of oxidation was from a problem with activation. A significant decrease in palmitoyl CoA synthetase activity in the heart homogenates and mitochondria of the diet-restricted pups took place. Presented at the 74th Annual Meeting of the American Oil Chemists' Society, Chicago, Illinois, May 1983. Deceased.  相似文献   

5.
Frank P. Bell  Edna V. Hubert 《Lipids》1982,17(12):900-904
The incorporation of [14C] mevalonate and [14C] acetate into squalene by rat liver slices was increased over 7-fold by the presence of 5% dimethylsulfoxide (DMSO) in the incubation medium. The stimulation of squalene synthesis was dose-related over the concentration range of 1–5% DMSO and did not affect the incorporation of [14C] mevalonate, into the C27-sterol fraction (cholesterol) but did increase (about 50%) incorporation into C30-sterol (lanosterol) at a level, of 5% DMSO. The stimulation of squalene synthesis was observed under both anaerobic (N2 atmosphere) and aerobic (ambient air or 95% O2/5% CO2) conditions and may represent a direct effect of DMSO on squalene synthetase. At a level of 5%, DMSO also stimulated 7-fold the incorporation of [14C] acetate into triglycerides by liver slices; this occurred without changes in incorporation into the phospholipid or free fatty acid fractions. The disproportionate increase in lipid labeling from [14C] acetate suggests that the effects of DMSO are not simply a matter of increasing [14C] acetate entry into the tissue.  相似文献   

6.
Livers removed from normal rats, from alloxan diabetic rats maintained on insulin for two weeks (ADI+), and from insulin-treated diabetic rats from which insulin had been withdrawn two days before use (AD) were perfused in vitro with 120 mg (468 μmoles) palmitic acid-1-C14. Under these conditions, output of TG (triglyceride) was depressed in livers from ADI+ rats and was negligible with livers from AD animals. The total incorporation of C14 into perfusate TG paralleled the chemical measurments of TG output. The concentration of hepatic TG increased during perfusion of livers from normal or ADI+ rats but decreased during perfusion of livers from AD animals. A load of 120 mg of palmitic acid/3 hr was inadequate to maintain net accumulation of TG in livers from AD rats; furthermore it is implicit in this observation that the total load of NEFA (nonesterified fatty acid) perfusing livers from AD rats must be increased considerably to obtain a fatty liver. The total incorporation of C14 into hepatic TG and the specific activity of hepatic TG were depressed during perfusion of livers from AD rats. The production of ketone bodies by livers from AD animals was about five times the normal rates; the output of ketone bodies did not differ from results of other experiments (1) in which the load of palmitic acid added to the medium was varied from 0–80 mg. These observations were discussed with reference to mechanisms for ketogenesis and fatty liver in alloxan diabetes.  相似文献   

7.
Frank P. Bell  Lori C. St. John 《Lipids》1993,28(12):1079-1085
Lifibrol, a new hypocholesterolemic agent with activity in humans, was examined in normal rats for its short-term and long-term effects on lipid homeostasis. Cholesterol (Chol) synthesis inhibition by lifibrol was demonstratedin vitro in liver minces from normal rats by following [1-14C]acetate ([14C]Ac) and DL-[2-14C]mevalonate ([14C]-MVA) incorporation into [14C]Chol. When administered at 50 mg/kg/d, lifibrol reduced plasma total Chol and triglycerides (TG) (P<0.001) within 24 h. The Chol reduction was largely a result of reduction of low density and very low density lipoprotein cholesterol (LDL+VLDL-chol) and a smaller decrease in high density lipoprotein cholesterol (HDL-chol). After 10 d, however, a rebound effect emerged, and after 41 d, plasma Chol, LDL+VLDL-chol, and HDL-chol were restored. In contrast, plasma TG remained at reduced levels (P<0.01). The rebound is attributed to counter-regulation of hepatic sterologenesis that was assessed bothex vivo andin vivo. Theex vivo incorporation of [14C]MVA and [14C]octanoate into [14C]Chol and total digitonin-precipitable [14C]sterols ([14C]DPS) in liver minces was increased 2-and 6-fold, respectively, in rats treated 6 d at 50 mg/kg. Similarly,in vivo incorporation of intraperitoneally injected [14C]Ac into hepatic [14C]DPS (2 h post-injection) was increased 2- to 5-fold at 50 mg/kg, and evidence for increased sterologenesis in nonhepatic tissue was also obtained. The increased hepatic sterologenesis, evident within 48 h, persisted out to 41 d of treatment by which time increases (P<0.002) in hepatic Chol and carcass total sterols were observed. Additionally, incorporation of injected [14C]Ac into hepatic [14C]TG was inhibited 60% by lifibrol (P<0.001), and the appearance of [14C]TG in plasma was reduced. Circulating free [14C]fatty acids ([14C]FFA) were also reduced, but hepatic [14C]FFA synthesis was unaffected, thus suggesting either a lesser release of newly formed FFA from liver or an enhanced removal from plasma.  相似文献   

8.
S. C. Cunnane  K. W. J. Wahle 《Lipids》1981,16(10):771-774
The effect of zinc deficiency on the Δ6-desaturation of [1-14C] linoleic acid was studied in mammary tissue microsomes from lactating rats. The rats were maintained on zinc-adequate (20 ppm zinc) or zinc-deficient (10 ppm zinc changing to 0.5 ppm zinc during last trimester) diets throughout gestation and for the first 3 days of lactation. Mammary tissue microsomes were incubated with [1-14C] linoleic acid and other samples of mammary tissue, mammary milk and the milk in the stomachs of the pups were analyzed for total fatty acid composition. In mammary microsomes from zinc-deficient rats, Δ6-desaturation of linoleic acid was 3.4 times greater than in microsomes from zinc-adequate rats. This change in metabolism of linoleic acid was reflected by comparable changes in the relative tissue and milk composition of linoleic and arachidonic acids and in the ratios of palmitic to palmitoleic acid, stearic to oleic acid and linoleic and arachidonic acid.  相似文献   

9.
The main goal of the present study was to evaluate the long-term effects of a perinatal palatable high-fat diet on the food intake and cholesterol profile of adult rats. Male Wistar rats (aged 22 days) were divided into two groups according to their mother’s diet during gestation and lactation (C p, n = 10; pups from control mothers; and HLp n = 10; pups from mothers fed a palatable high-fat diet). At the 76th day, pups were housed individually for 14 days, and daily food consumption was determined during a period of 6 days. Blood from 100-day-old rats was sampled by cardiac puncture. Fasting (12 h) serum glucose, total cholesterol, LDL-C, HDL-C, triglycerides (TG), and VLDL-C levels were determined. The measurement of food intake was higher in the animals submitted to a hyperlipidic diet during the perinatal period. Serum total cholesterol, LDL-C, HDL-C, TG, VLDL-C and glycemia were increased in the HLp group compared to the control group. Our findings show that an early life environment with a high-fat diet can contribute to metabolic disease in later life.  相似文献   

10.
Females ofStegobium paniceum (L.) produce a sex pheromone that causes an excitation and attraction of the males. Male response was highest 5–12 days after adult emergence. Pheromone titer of unmated females increased steadily after 1 day, reached a plateau after 5 days, and continued until at least 14 days. Mature males showed a threshold responsiveness of 3 × 10?7 μg pheromone. The pheromone titer per female ranged from 50 to 200 ng. On the basis of a high-resolution mass spectrum the empirical formula of the pure isolated pheromone molecule was determined to be C13H20O3. The pheromone was further defined by its Chromatographic behavior and spectroscopic properties.  相似文献   

11.
The incorporation of [1-14C]linoleic acid (LA) into lipids ofMortierella ramanniana var.angulispora was studied to determine which lipid classes participated in the δ6-desaturation of [1-14C]LA. [1-14C]LA was rapidly taken up into fungal cells and esterified into various lipids. Comparison of the profile of [1-14C]LA incorporation between fungal cells at the exponential growth phase and the stationary growth phase showed that [1-14C]LA incorporation into most lipids—except for triacylglycerol (TG) and phosphatidylcholine (PC)—were greatly reduced at the stationary growth phase. Desaturation of [1-14C]LA into λ-linolenic acid (GLA) readily occurred at the exponential growth phase, but was greatly decreased at the stationary growth phase. Moreover, pulse-chase experiments revealed that the radiolabel incorporated into phosphatidylserine (PS) and PC rapidly turned over, while that in TG and diacylglycerol (DG) accumulated after the 4 hr chase. In addition to the change of the radiolabel in individual lipids, the content of radiolabeled GLA converted from [1-14C]LA varied with individual lipids. In phospholipids such as PC, phosphatidylethanolamine (PE) and PS, radiolabeled GLA rapidly increased after 1 hr and then decreased after 4 hr. On the other hand, a gradual increase in radiolabeled GLA until 4 hr was observed in TG. These results suggest that LA, which has been esterified into phospholipids such as PC, PE and PS, is readily desaturated to GLA, which is then transferred to TG. These differences in the fate of GLA derived from LA between phospholipids and neutral lipids may be reflected in the GLA content in the individual lipids.  相似文献   

12.
In this study, some kinds of multilayer (double and triple) electrochromic (EC) surfaces were prepared using layer-by-layer (LBL) electrodeposition techniques. Polypyrrole (PPy) was deposited as the first layer and the upper layers were changed. EC characteristics were investigated by spectroelectrochemical measurements. Surface roughness parameters (Root Mean Square-RMS) were determined using atomic force microscopy (AFM) technique. The results showed that different color options may be obtained by altering LBL deposition of EC polymers. Equilibrium water contact angle (ϴequwater) measurements showed that incorporation of hydrophilic poly(3,4-ethylenedioxythiophene) PEDOT in LBL EC surfaces resulted in a decrease in the contact angle. However, the ϴequwater of multilayer films increased with the incorporation of the hydrophobic polycarbazole (PCarb) layer.  相似文献   

13.
Y. -Y. Yeh  V. L. Streuli  P. Zee 《Lipids》1977,12(4):367-374
The regulation of hepatic ketogenesis, as related to the metabolism of fatty acids through oxidative and synthetic pathways, was studied in developing rats. [1-14C] palmitate was used as a substrate to determine the proportions of free fatty acids utilized for the production of ketone bodies, CO2 and complex lipids. Similar developmental patterns of hepatic ketogenesis were obtained by measuring the production of either [14C]acetoacetate from exogenous [1-14C] palmitate or the sum of unlabeled acetoacetate and β-hydroxybutyrate from endogenous fatty acids. The production of total ketone bodies was low during the late fetal stage and at birth, but increased rapidly to a maximum value within 24 hr after birth. The maximal ketogenic capacity appeared to be maintained for the first 10 days of life.14CO2 production from [1-14C] palmitate increased by two- to fourfold during the suckling period, from its initial low rate seen at birth. The capacity for synthesis of total complex lipids was low at birth and had increased by day 3 to a maximal value, which was comparable to that of adult fed rats. The high lipogenic capacity lasted throughout the remaining suckling period. When ketogenesis was inhibited by 4-pentenoic acid, the rate of synthesis of complex lipids did not increase despite an increase in unutilized fatty acids. During the mid-suckling period, approximately equal amounts of [1-14C] palmitate were utilized for the synthesis of ketone plus CO2 and for complex lipid synthesis. By contrast, in adult fed rats, the incorporation of fatty acids into complex lipids was four times higher than that of ketone plus CO2. These observations suggest that stimulated hepatic ketogenesis in suckling rats results from the rapid oxidation of fatty acids and consequent increased production of acetyl CoA, but not from impaired capacity for synthsis of complex lipids.  相似文献   

14.
Radiation detector was made of a high-quality CVD polycrystalline diamond composed of frost column like structure diamond grains, and induced charge distribution spectra and drift velocities were measured by using alpha particles. As a result, the CVD polycrystalline achieved maximum induced charge of 83% of HP/HT type IIa diamond. Moreover, the CVD crystal had lower charge loss on electrons compared with the HP/HT type IIa diamond. Drift velocities of electrons and holes were ve = 7.7 × 104 and vh = 7.3 × 104cm/s at an electric field of 20 kV/cm, respectively. In addition, response function measurement for 14 MeV neutrons was carried out.  相似文献   

15.
Confluent skin fibroblasts from normal humans were incubated in serum free medium with up to 100 nmole/mL eicosapentaenoic acid (EPA; bound to albumin in a 4.6∶1 ratio) and compared with cells incubated with oleic acid (OA) at similar concentrations. The rate of [14C]OA incorporation into triacylglycerol (TG) (nmol/mg/h) was approximately 5-fold greater than that of [14C]EPA. The mass of TG formed after incubation of fibroblasts with EPA was also significantly lower than that formed with OA (43.2 ±9.3vs. 59.5±6.6 μg/mg cell protein, respectively,P=0.006). The addition of excess, unlabeled EPA reduced the rate of incorporation of [14C]OA into TG whereas unlabeled OA stimulated incorporation of [14C]EPA into TG. When the cells were preincubated with human serum basic proteins (BP I, II and III), the mass of TG formed (compared to baseline) was significantly higher with the basic proteins whether OA or EPA was studied. Only BP I significantly stimulated the mass of cell phospholipids, an effect that occurred with either OA or EPA in the medium. The results suggest that in cultured normal human fibroblasts, OA is a better substrate for TG synthesis than EPA and that this effect may be accentuated by the presence of the basis proteins.  相似文献   

16.
Pregnant rats were randomly allocated to one of 3 experimental dietary groups: Group 1–15.5% butter, 2% cholesterol, 0.78% sodium cholate purified diet; Group 2-standard rat diet with the addition of 10% lard and 2% cholesterol, and Group 3-standard rat diet. Plasma and milk cholesterol at 10 days postpartum were significantly elevated in dams fed exogenous cholesterol. The rat of incorporation of [1-14C] acetate into digitonin-precipitable sterols of mammary tissue slices from dams in Group 1 and Group 2 was eight-fold and two-fold, respectively, less than controls. Mammary tissue cholesterol was greater in dams fed dietary cholesterol. Thus, our data, for the first time, demonstrate that cholesterol synthesis in lactating rat mammary tissue is suppressed following cholesterol feeding. In a second experiment, the rate of incorporation of [1-14C] acetate into digitonin-precipitable sterols in kidney and lung tissue of Group 1 rats was suppressed; however, this response was not as marked as that observed in lactating mammary tissue. The concentration of cholesterol in kidney and lung was greater than controls. These results suggest that extrahepatic inhibition of cholesterol synthesis exists in the rat with a concomitant increase in tissue cholesterol.  相似文献   

17.
A field experiment was conducted on a poorly-drained Aeric Paleaquult in northeastern Thailand to determine the effect of N and S fertilizers on yield of rainfed lowland rice (Oryza sativa L.) and to determine the fate of applied15N- and35S-labeled fertilizers. Rice yield and N uptake increased with applied N but not with applied S in either sulfate or elemental S (ES) form. Rice yield was statistically greater for deep placement of urea as urea supergranules (USG) than for all other N fertilizer treatments that included prilled urea (PU), urea amended with a urease inhibitor (phenyl phosphorodiamidate), and ammonium phosphate sulfate (16% N, 8.6% P).The applied15N-labeled urea (37 kg N ha–1) not recovered in the soil/plant system at crop maturity was 85% for basal incorporation, 53% for broadcast at 12 days after transplanting (DT), 27% for broadcast at 5–7 days before panicle initiation (DBPI), and 49% for broadcast at panicle initiation (PI). The basal incorporated S (30 kg ha–1) not recovered in the soil/plant system at crop maturity was 37% for sulfate applied as single superphosphate (SSP) and 34% for ES applied as granulated triple superphosphate fortified with S (S/GTSP). Some basal incorporated15N and35S and some broadcast15N at PI was lost by runoff. Heavy rainfall at 3–4 days after basal N incorporation and at 1 day after PI resulted in water flow from rice fields at higher elevation and total inundation of the 0.15-m-high15N and35S microplot borders. Unrecovered15N was only 14% for 75 kg urea-N ha–1 deep placed as USG at transplanting. This low N loss from USG indicated that leaching was not a major N loss mechanism and that deep placement was relatively effective in preventing runoff loss.In order to assess the susceptibility of fertilizer-S to runoff loss, a subsequent field experiment was conducted to monitor35S activity in floodwater for 42 days after basal incorporation of SSP and S/GTSP. Maximum35S recoveries in the floodwater were 19% for SSP after 7 days and 7% for S/GTSP after 1 day. Recovery of35S in floodwater after 14 days was 12% for SSP and 3% for S/GTSP.This research suggests that on poorly drained soils with a low sorption capacity, a sizeable fraction of the fertilizer S and N remains in the floodwater following application. Runoff could then be an important mechanism of nutrient loss in areas with high probability for inundation following intense rainfall.  相似文献   

18.
To determine the production of recombinant human protein C (rec-hPC) in milk, we created two homozygous mice lines for the goat β-casein/hPC transgene. Females and males of both lines (#10 and #11) displayed normal growth, fertility, and lactated normally. The copy number of the transgene was about fivefold higher in #10 line as compared to #11 line. mRNA expression of the transgene was only detected in the mammary glands of both lines. Furthermore, mRNA expression was fourfold higher on day 7 than on day 1 during lactation. Northern blot analysis of mRNA expression in the #10 line of transgenic (Tg) mice indicated a strong expression of the transgene in the mammary glands after seven days of lactation. Comparison of rec-hPC protein level with that of mRNA in the mammary glands showed a very similar pattern. A 52-kDa band corresponding to the hPC protein was strongly detected in mammary glands of the #10 line during lactation. We also detected two bands of heavy chain and one weak band of light chain in the milk of the #10 and #11 lines. One single band at 52 kDa was detected from CHO cells transfected with hPC cDNA. hPC was mainly localized in the alveolar epithelial cell of the mammary glands. The protein is strongly expressed in the cytoplasm of the cultured mammary gland tissue. hPC protein produced in milk ranged from 2 to 28 ng/mL. These experiments indicated that rec-hPC can be produced at high levels in mice mammary glands.  相似文献   

19.
Inorganic electride [Ca24Al28O64]4+(4e) was successfully synthesized via a reaction of Ca12Al14O33 (C12A7), Ca3Al2O4 (C3A), and Al powder at 1050°C for 5 minutes heated by SPS system. The as-prepared polycrystalline C12A7:e electride exhibits an electron concentration of 2.3 × 1021 cm−3 and an optical absorption bands at 2.5ev under room temperature. Electron concentration was also determined by thermogravimetry (TG) and differential thermal analysis (DTA). Furthermore, the molecular structure was investigated by Micro Raman measurements; the appearance of the band at 186 cm−1 strongly suggested the formation of C12A7:e electride. These results not only suggest a novel precursor for fabricating mayenite electrides but also make it possible to produce efficiently the electride in large volume.  相似文献   

20.
Dietary supplements of olive oil (OO) or fish oil (FO) during the first (G1: day 1–60) or second half of gestation (G2: day 60 to term, day 115) were offered to pregnant sows. The proportion of fatty acids in milk and plasma were determined by gas chromatography. When supplements were given during G1, the proportions of oleic acid (OA) and arachidonic acid (AA) in the plasma were higher in the OO group than in the FO group, whereas docosahexaenoic acid (DHA) was higher in the latter group at day 56 of gestation. These differences in plasma DHA were still apparent at day 7 of lactation. Similarly, DHA was also higher in the colostrum and milk on days 3 and 21 of lactation and in the plasma of piglets from FO dams compared to the OO group, whereas AA was lower. When the FO supplement was given during G2, AA was lower and DHA higher in the plasma at day 105 of gestation and at day 7 of lactation compared with the OO group. Likewise, DHA was greater in FO than in OO animals during lactation in colostrum and in milk on days 3 and 21 of lactation, and in 3-day old suckling piglets plasma, whereas AA was lower in these animals. Thus, maternal adipose tissue plays an important role in the storage of dietary long-chain polyunsaturated fatty acids (LCPUFA) during G1. They are mobilized around parturition for milk synthesis, and an excess of dietary n-3 LCPUFA decreases the availability of AA in suckling newborns.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号