对二溴苯的超声合成

对二溴苯为白色结晶,有二甲苯的气味,不溶于水,溶于乙醇和苯.主要用于有机合成及作为染料中间体.对二溴苯的传统合成方法为: 此反应需12min引发,20-30℃加热1h,然后升温到60℃再加热45min后停止反应,经2次蒸馏后可得对二溴苯,产率为10%.本文在传统合成对二溴苯的基础上,利用超声波激励反应,可在较短时间内、较低温度下获得产率为80%的对二溴苯.     

The effects of simvastatin and cholestyramine,alone and in combination,on hepatic cholesterol metabolism in the male rat

The influence of dietary simvastatin, cholestyramine, and the combination of simvastatin plus cholestyramine on hepatic cholesterol metabolism has been investigated in male rats. Recovery from the effects of the drugs was also investigated by refeeding normal chow for 24 h. Both drugs, alone and in combination, increased 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase activityin vitro, but activity returned toward control values, after drug withdrawal. Acyl-CoA:cholesterol acyltransferase (ACAT) was significantly reduced (P<0.001) by simvastatin (−75%), cholestyramine (−71%), and by the drug combination (−81%), due both to a decrease in microsomal cholesterol and to nonsubstrate-dependent modulation of enzyme activity. Refeeding control diet increased ACAT activity but not to control levels. The enhanced activity arose partly from higher microsomal cholesterol and partly from increases in total enzyme activity. Cytosolic neutral cholesteryl ester hydrolase (CEH) activity was substantially elevated by simvastatin (3-fold) and by the drug combination (6-fold), whereas the effect of cholestyramine was smaller (1.5-fold). Normal chow for 24 h only partially returned cytosolic CEH activity to control values. Microsomal CEH activity was increased by simvastatin, alone and in combination with cholestyramine (1.4 to 1.7-fold), and was also enhanced, in the cholestyramine-treated animals, following drug withdrawal. Removal of simvastatin did not allow recovery of this enzyme activity, while withdrawal of the drug combination led to values 29% below controls. The results indicate that in the rat, simvastatin and cholestyramine alter both ACAT and CEH activity, as well as inhibiting HMG-CoA reductase activity.     

Absorption,excretion, metabolism and cardiovascular effects of beetroot extract in the rat

The uptake, metabolism and excretion of betanin from beetroot extract were studied in the rat after iv injection or peroral administration in vivo, and in the isolated perfused liver in vitro. When injected iv, betanin was almost completely recovered in the urine. When given orally only 3% was recovered in the urine and 3% in the faeces after 24 hr. In the isolated perfused liver very little betanin was found in the bile, and most of the added betanin was recovered from the perfusion fluid. In studies in vitro it was found that betanin was largely metabolized by the tissues lining the gastro-intestinal tract. It is concluded that orally-administered betanin is poorly absorbed, and that the majority of it is metabolized in the gut. Betanin injected iv had effects on the cardiovascular system, transiently increasing the blood pressure and heart rate. It also increased the magnitude of the contractions of an isolated portal vein, in vitro. Both the in vivo and the in vitro effects could be partially blocked by specific adrenergic and cholinergic blockers, but the mechanism of the cardiovascular effects of betanin remains to be determined.     

The metabolism of linoleic and arachidonic acids in rat testis

Linoleic and arachidonic acids, labeled with¹⁴C and injected intratesticularly, were used to study with time the interconversion of polyunsaturated fatty acids in rat testis and their incorporation into the major lipid classes. With both substrates¹⁴C activity was readily incorporated into longer chain, more highly unsaturated fatty acids. After the injection of 1-¹⁴C-linoleic acid the major portion of the¹⁴C was found in palmitic, linoleic, 8,11,14-eicosatrienoic, 5,8,11,14-eicosatetraenoic, 7,10,13,16-docosatetraenoic and 4,7,10,13,16-docosapentaenoic acids. Hydrogenation of the total fatty acids isolated from rat testes after intratesticular injection of 1-¹⁴C-linoleate revealed that the polyenoic acids hydrogenating to lignoceric acid (previously characterized as 9,12,15,18-tetracosatetraenoate and 6,9,12,15,18-tetracosapentaenoate) had a relatively high specific activity. After the injection of 1-¹⁴C-arachidonate significant¹⁴C activity was found in palmitate, 7,10,13,16-docosatetraenoate, 4,7,10,13,16-docosapentaenoate, 9,12,15,18-tetracosatetraenoate and 6,9,12,15,18-tetracosapentaenoate. The biosynthesis of the ω⁶ polyunsaturated fatty acids in rat testis is discussed in relation to these data. Investigation of the distribution of label in the complex lipid fractions demonstrated the majority of the¹⁴C activity to be present in phosphatides and triglycerides after injection of either of these¹⁴C substrates with only small quantities being present as nonesterified acids. At the time periods studied the polyenoic acids of triglycerides had a higher specific activity than the corresponding acids of phosphatides with the exception of linoleate. Presented in part at the Meeting of the American Institute of Nutrition, Atlantic City, April 1968 and at the AOCS Meeting in New York, April 1969. These data were taken from a thesis submitted by R. B. Bridges in partial fulfillment of the requirements for the Ph.D. degree, Vanderbilt University.     

Cholesterol synthesis in the vertebrate retina: Effects of U18666A on rat retinal structure, photoreceptor membrane assembly, and sterol metabolism and composition

Treatment of neonatal rats with U18666A, an inhibitor of desmosterol Δ²⁴-reductase, results in accumulation of desmosterol (Δ^5,24) and depletion of cholesterol (Δ⁵) in various bodily tissues and also causes cataracts. We evaluated the effects of U18666A on the sterol composition, de novo sterol synthesis, and histological structure of the retina. Neonatal Sprague-Dawley rats were injected subcutaneously with U18666A (15 mg/kg, in olive oil) every other day from birth through 3 wk of age; in parallel, control rats received olive oil alone. At 21 d, treated and control groups each were subdivided into two groups: one group of each was injected intravitreally with [³H]acetate; retinas were removed 20 h later and non-saponifiable lipids (NSL) were analyzed by radio-high-performance liquid chromatography. The other group was injected intravitreally with [³H]leucine; 4 d later, one eye of each animal was evaluated by light and electron microscopy and light microscopic autoradiography, while contralateral retinas and rod outer segment (ROS) membranes prepared thereform were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis/fluorography. In the treated group, the Δ⁵/Δ^5,24 mole ratio of retinas was ca. 1.0, and >88% of the NSL radioactivity was in Δ^5,24; in contrast, control retinas had Δ⁵/Δ^5,24 >170, with >80% of the NSL radioactivity in Δ⁵. Retinal histology, ultrastructure, ROS renewal rates, and rhodopsin synthesis and intracellular trafficking were comparable in both treated and control animals. These results suggest that desmosterol can either substitute functionally for cholesterol in the retina or it can complement subthreshold levels of cholesterol by sterol synergism.     

The metabolism of native and randomized butterfat chylomicrons in the rat is similar

Reportedly’ randomly rearranging the position of fatty acids (FA) in butterfat triacylglycerol (TAG) by interesterification’ thereby lowering the proportion of saturated FA in the sn-2 position’ reduces its hypercholesterolemic and hypertriglyceridemic properties when fed to humans. The aim of this work was to determine if these reductions in plasma cholesterol and TAG could be explained by an improved rate of clearance from the plasma of chylomicrons composed of randomized butterfat’ using a rat model. Acute chylomicron clearance studies demonstrated no differences in fractional clearance rates of cholesteryl esters and TAG from the plasma of rats infused with chylomicrons produced from gastric feeding of either native (NBF) or randomized (RBF) butterfat. Although there was a 14% decrease in the level of saturated FA occupying the sn-2 position of TAG in RBF compared with NBF’ this difference became negligible (∼5%)’ following digestion of the fat and subsequent repackaging of TAG into chylomicrons. These observations suggest that the previously observed reduction in hypercholesterolemic properties of randomized butterfat in rat is unlikely to be explained by improved clearance of chylomicron TAG.     

4,4'-二胺基-2,2',6,6'-四甲基二苯基环己烷的合成与纯化

在浓盐酸中由环己酮和２,６－二甲基苯胶一步合成了多取代基的４,４＇－二胺基－２,２＇,６,６＇－四甲基二苯基环己烷。报道了该二胺的纯化,井使用元素分析、红外光谱、核磁共振谱等分析手段对其进行了表征。     

The total synthesis of dilinoleoylphosphatidylserine and its activity in blood clotting systems

A total synthesis ofdl-phosphatidyl-(dilinoleoyl)-l-serine was achieved by the acylation of the barium salt of the phthalimidomethyl ester of glycerophosphoryl-n-anisyloxycarbonyl-l-serine. The dilinoleoyl intermediate was treated with hydrazine to remove the phthalimidomethyl group and with hydrogen chloride to remove the anisyloxycarbonyl protecting group. The resulting phosphatidylserine was purified by Rouser's methods, solubilized, and tested for biological activity in the antithromboplastin, recalcification, and Hicks-Pitney tests. It was found to have about the same anticoagulant activity as beef brain phosphatidylserine and hence was more active than the less unsaturated phosphatidylserine synthesized earlier. An abstract of the material in this paper appeared in Fed. Proc.24, No. 727 (1965).     

Perfluorodecanoic acid and lipid metabolism in the rat

Alterations in lipid metabolism were axamined in adult male Sprague-Dawley rats seven days after a single intraperitoneal injection of perfluorodecanoic acid (PFDA; 20, 40 or 80 mg/kg). Because PFDA treatment caused a dose-related reduction in feed intake, the response of vehicle-treated rats pair-fed to those receiving PFDA was monitored to distinguish direct effects of the perfluorinated fatty acid from those secondary to hypophagia. Carcass content of lipid phosphorus and free cholesterol decreased in dose-dependent fashion in both PFDA-treated and pair-fed rats. Carcass triacylglycerols diminished in a similar manner, yet PFDA-treated rats at each dose had a higher concentration of neutral acylglycerols than their vehicle-treated, pair-fed counterparts. In vehicle-treated, pair-fed rats at the 80 mg/kg dose level, lipid phosphorus and free cholesterol as a proportion of carcass fat increased, whereas the share of the triacyl-glycerols declined. Because of the higher concentration of triacylglycerols in the carcass of rats treated with 80 mg/kg PFDA, enrichment of lipid phosphorus and free cholesterol in carcass fat was less than in their pair-fed partners. The amount of lipid phosphorus and free cholesterol per hepatocyte was similar in both PFDA-treated rats and their pair-fed partners. Liver triacyl-glycerols were markedly increased in PFDA-treated rats. A similar but less extensive augmentary effect of PFDA on hepatic esterified cholesterol was found. Concentration of triacylglycerols in plasma was not elevated in PFDA-treated rats, in spite of hepatic accumulation of esterified compounds. Also, the plasma level of free fatty acids and 3-hydroxybutyrate was similar in all treatment groups, including those receiving PFDA. Thus, the administration of PFDA appears to divert fatty acids from oxidation toward esterification in the liver.     

Al4SiC4的性能、制备和应用

介绍了一种待研发的新型三元碳化物Al4SiC4(碳硅化铝)的组成和基本性能,并重点讨论了Al4SiC4的各种合成和制备方法,如固相反应烧结法、高温自蔓延法等的原理及效果.首先讨论了Al4SiC4材料的基本性能、抗氧化性能和抗水化性能,比较了Al4SiC4和其他材料之间的性能差异,并介绍了Al4SiC4的应用范围;最后对Al4SiC4材料的合成方法和性能进行了总结,同时指出了碳硅化铝材料作为新型耐火材料的研究和使用的进一步研究方向.     

星状爆炸物中间体N,N-二苯基-4-碘代苯胺的合成与表征

以二苯胺和对硝基苯胺为原料,通过胺基的重氮化碘代、乌尔曼反应、硝基还原和胺基的再次重氮化碘代反应,合成得到了三芳胺类星状爆炸物中间体N,N-二苯基-4-碘代苯胺。此一系列反应条件较温和,产率较高,中间体和产物纯化处理较容易。使用核磁和质谱对其结构进行了表征,并测得它在三氯甲烷溶液中的紫外吸收光谱和晶体的光致发光光谱。     

Disposition and metabolism of pristane in rat

The fate of pristane (2,6,10,14-tetramethylpentadecane), a widespread isoprenoid hydrocarbon, has been studied in rats after a single per os administration of³H-labeled pristane. The balance study showed an extensive fecal excretion (66%) mainly as unchanged hydrocarbon, whereas about 14% of ingested pristane was excreted in urine as pristane metabolites and tritiated water. After one wk, 8.3% of the ingested³H still was stored in the carcass, and radioactive distribution in tissues and organs showed a preferential incorporation into adipose tissue and liver. Over 75% of the radioactivity stored in the carcass was associated with pristane metabolites and tritiated water. Tissue metabolites were characterized by thin layer chromatography, gas chromatography and mass spectrometric analyses. Four metabolites were identified: pristan-1-ol, pristane-2-ol, pristanic acid and 4,8,12-trimethyltridecanoic acid. These demonstrate that this isoprenoid hydrocarbon undergoes subterminal hydroxylation or terminal oxidation followed by the classical β-oxidation process. Incorporation of metabolites in phospholipids and more particularly in the phosphatidylserine fraction has been observed and is discussed.     

Dietary lipid,fatty acid synthesis and cholesterol metabolism in aging rats

Male and female rats were fed diets containing 2% of calories as corn oil or that plus 40% of calories as beef tallow or corn oil. After 3, 6, 12 and 18 months groups were given 4-¹⁴C-cholesterol ip, and feces were collected for 9 days. Just prior to necropsy³H-acetate was administered ip. Samples of serum, liver, heart and carcass were obtained for analysis. Concentrations of fatty acids and cholesterol, synthesis of those and recovery of ring-labeled steroid are reported. Mortality from acute respiratory disease was very high in male rats fed beef tallow or low fat diets and very low in those fed the corn oil diet. In females, only beef tallow diet resulted in a high mortality rate, and this was lower and at a later age than in males. The most notable effects of age were in relation to fatty acid synthesis and presence of¹⁴C-acidic steroid in the carcass. In 3-month-old rats both fats depressed fatty acid synthesis in comparison to the low fat diet. At later ages beef fat ceased to depress fatty acid synthesis in both sexes. Corn oil continued to depress fatty acid synthesis up to 12 months in males and 18 months in females. The presence of¹⁴C-acidic steroid in carcass was substantial in 6-month-old rats and constituted ca. 40% of recovered¹⁴C in 18-month-old rats. The possibility that the increase in acetate incorporation into fatty acids with age in fat feeding is related to chain elongation rather than de novo synthesis is discussed. Both the presence and amount of acidic steroid in the carcass are notable and may be of importance in constructing models of cholesterol turnover. Presented in part at the AOCS Sterol Symposium, April 1970, and the Federation of American Societies for Experimental Biology, April 1971. Scientific Series Paper No. 1536, Colorado Agricultural Experiment Station.     

The metabolism of polyunsaturated fatty acids in rat sertoli and germinal cells

The metabolism of [1-¹⁴C]linoleic, [1-¹⁴C]arachidonic and [3-¹⁴C]docosa-4,7,10,13,16-pentaenoic acids was investigated after intratesticular injection of the labeled compounds and isolation of rat Sertoli and germinal cells. Following injection of either¹⁴C-linoleate or¹⁴C-arachidonate, the specific activity (sp act) of docosa-4,7,10,13,16-pentaenoic acid of Sertoli cells was greater than that of the germinal cells. The data suggest that the Sertoli cells are more active in the biosynthesis of the 22-carbon pentaene than the germinal cells. Differences between these 2 cell types were also noted in the distribution of the incorporated¹⁴C among the various lipid classes. Following intratesticular injection of¹⁴C-docosapentaenoic acid, a greater proportion of the recovered¹⁴C in Sertoli cells than in germinal cells was present in 20-carbon fatty acids, suggesting a greater activity in Sertoli cells in the metabolism of the pentaene. The major portion of the recovered¹⁴C in both cell types was present in triacylglycerols during early time periods and in phospholipids after 24 hr. The possibility of transfer of biosynthesized docosapentaenoic acid from Sertoli to germinal cells is discussed.