Effects of L-Carnitine on Sucrose-Induced Hyperlipidaemia

L-Carnitine, L-(−)-β-hydroxy-γ-trimethylaminobutyrate, plays an important role as a factor necessary for the transport of long-chain fatty acids into the mitochondria. In order to investigate the influence of L-carnitine on hyperlipidaemias, the experimental model of the sucrose-induced hypertriglyceridaemia of the rat was used. In these experiments L-carnitine in the dose of 11 mg per day and 100 g body weight (over the period of 1 week) was able to antagonize the sucrose-induced hypertriglyceridaemia and the increase of serum free fatty acid level in female rats of the Wistar strain. Carnitine administration did not change the activities of lipogenic enzymes and fatty acid synthesis in the liver. However, L-carnitine increases the rate of hepatic fatty acid oxidation. Our results indicate a hypotriglyceridemic and free fatty acid lowering effect of L-carnitine, and suggest the use of this compound in the therapy of hyperlipidaemias.     

Effects of L-Carnitine Supplementation in Sows

In recent years L-carnitine has been used increasingly in animals. This review gives an overview of the effects of dietary L-carnitine supplementation during pregnancy and lactation on the reproductive performance of sows. In one investigation L-carnitine supplementation during pregnancy increased the number of piglets born to sows. Other studies showed heavier litters in sows supplemented with L-carnitine compared with control sows, and litters of L-carnitine supplemented sows gained more weight during the suckling period than litters of control sows. This effect might be due to more vigorous suckling by piglets of L-carnitine supplemented sows, causing the sows’ milk production to rise. At negative energy balance during lactation L-carnitine supplemented sows are able to mobilize more energy from adipose tissue, which can be used for the production of surplus milk. In conclusion, recent studies clearly show that dietary L-carnitine supplementation increases the reproductive performance of sows. This finding suggests that the amount of L-carnitine synthesized endogenously does not cover the requirement for maximum sow performance during pregnancy and lactation.     

Large Scale Bioprocess for the Production of Optically Pure L-Carnitine

A competitive production method using the biotransformation of 4-butyrobetaine to enantiomerically pure L-carnitine was developed and scaled-up by Lonza. The process produces L-carnitine in 99.5% yield, and >99.9% enantiomeric excess (ee). Continuous and discontinuous processes were developed but the fed-batch process was found to be economically the most favourable process mode.     

L-Carnitine Supplementation: A New Paradigm for its Role in Exercise

Early research investigating the effects of L-carnitine supplementation has examined its role in substrate metabolism and in acute exercise performance. These studies have yielded equivocal findings, partially due to difficulties in increasing muscle carnitine concentrations. However, recent studies have proposed that L-carnitine may play a different role in exercise physiology, and preliminary results have been encouraging. Current investigations have theorized that L-carnitine supplementation facilitates exercise recovery. Proposed mechanism is as follows: 1) increased serum carnitine concentration enhances capillary endothelial function; 2) increased blood flow and reduced hypoxia mitigate the cascade of ensuing, destructive chemical events following exercise; 3) thus allowing reduced structural damage of skeletal muscle mediated by more intact receptors in muscle needed for improved protein signaling. This paradigm explains decreased markers of purine catabolism, free radical formation, and muscle tissue disruption after resistance exercise and the increased repair of muscle proteins following long-term L-carnitine supplementation.     

What to Learn from a Comparative Genomic Sequence Analysis of L-Carnitine Dehydrogenase

In contrast to eukaryotic cells certain eubacterial strains have acquired the ability to utilize L-carnitine (R-(–)-3-hydroxy-4-(trimethylamino)butyrate) as sole source of energy, carbon and nitrogen. The first step of the L-carnitine degradation to glycine betaine is catalysed by L-carnitine dehydrogenase (L-CDH, EC 1.1.1.108) and results in the formation of the dehydrocarnitine. During the oxidation of L-carnitine a simultaneous conversion of the cofactor NAD⁺ to NADH takes place. This catabolic reaction has always been of keen interest, because it can be exploited for spectroscopic L-carnitine determination in biological fluids – a quantification method, which is developed in our lab – as well as L-carnitine production.Based on a cloned L-CDH sequence an expedition through the currently available prokaryotic genomic sequence space began to mine relevant information about bacterial L-carnitine metabolism hidden in the enormous amount of data stored in public sequence databases. Thus by means of homology-based and context-based protein function prediction is revealed that L-CDH exists in certain eubacterial genomes either as a protein of approximately 35 kDa or as a homologous fusion protein of approximately 54 kDa with an additional putative domain, which is predicted to possess a thioesterase activity. These two variants of the enzyme are found on one hand in the genome sequence of bacterial species, which were previously reported to decompose L-carnitine, and on the other hand in gram-positive bacteria, which were not known to express L-CDH. Furthermore we could not only discover that L-CDH is located in a conserved genetic entity, which genes are very likely involved in this L-carnitine catabolic pathway, but also pinpoint the exact genomic sequence position of several other enzymes, which play an essential role in the bacterial metabolism of L-carnitine precursors.     

L-Carnitine, Immunomodulation, and Human Immunodeficiency Virus (HIV)-related Disorders

The use of pharmacologic doses of the conditionally-essential nutrient L-carnitine (LC) has been associated with positive effects on the immune system. We have recently suggested that this property of LC could be mediated through activation of the glucocorticoid receptor alpha. Human immunodeficiency virus (HIV)-infected individuals, especially those on antiretroviral therapy, may become LC-deficient. This evidence, together with the immunomodulatory properties of LC, its known major role in lipid and energy metabolisms, and its proposed antiapoptotic and neuroprotective actions, have encouraged the use of LC supplementation as a potential treatment for HIV-related disorders, such as lipodystrophy and peripheral neuropathy. Preliminary results, mostly from small-scale uncontrolled studies are conflicting, whilst larger controlled trials are warranted.     

Protective Effects of L-Carnitine on Myocardium of Experimentally Diabetic Rats with Additional Ischaemia and Reperfusion

We investigated the protective effects of L-carnitine against damage to the heart caused by diabetes-induced alterations and additional ischaemia and reperfusion in diabetic BB/OK rats using histological techniques, morphometry, biochemical parameters of oxidative stress, and SOD expression. The results revealed that diabetes-induced morphological changes were partly improved or nearly prevented by substitution of L-carnitine, which also seemed to improve the reduced tolerance of diabetic myocardium towards ischaemia/reperfusion with respect to morphological parameters. Immunohistochemical and biochemical parameters of oxidative stress such as SOD protein expression as well as SOD and GPx activity indicate increased free oxygen radical level in the ischaemic/reperfused diabetic myocardium, which is clearly decreased by L-carnitine treatment. We suggest that L-carnitine may be an adequate “causal” agent in the protection of myocardial alterations in diabetes with additional ischaemia and reperfusion, as it stabilizes mitochondrial and cellular function and acts through its antioxidative or radical scavenging potential. Further investigations are necessary to determine an approach towards adjuvant treatment of diabetic myocardial complications using L-carnitine.     

Current Methods for Determination of <Emphasis Type="Italic">L</Emphasis>-Carnitine and Acylcarnitines

Summary. L-Carnitine as endogenous compound plays an important role within several metabolic pathways and a deficiency of L-carnitine can cause adverse effects in physiological and/or mental state of health and disease. The prevention of diseases related to carnitine deficiency requires, first of all, the exact determination of L-carnitine and its esters in biological material at pmol/cm³ level. A series of analytical procedures based on biochemical assays as well as on physical methods are available today. Determination of free and total carnitine is sometimes sufficient for a clinical diagnosis, but in most cases, such as in newborn screening for genetic disorders, detailed qualitative and quantitative L-carnitine/acylcarnitine profiling is needed. Technological progress has also revolutionized the determination of carnitines. Today, comprehensive and diagnostically relevant information can be obtained by mass spectrometry. An overview is given of the technical and methodological developments in carnitine analysis and some applications, such as in neonatal screening, diabetes mellitus, and cardiomyopathy.     

L p-estimates for Schr?dinger operators

L ^p-estimates of the resolvent for a large class of Schr?dinger operators are proved. Combining this with the almost analytic continuations, we obtainL ^p-estimates for functions of Schr?dinger operators.     

三环已基锡L-扁桃酸酯配合物的合成、结构及性质

三环己基氢氧化锡与L-扁桃酸(物质的量比1:1)在苯和乙醇混合溶剂中反应合成了三环己基锡L-扁桃酸酯。 经X射线衍射方法测定了其晶体结构,配合物属斜方晶系,空间群为P2₁2₁2₁,晶体学参数a=0.80825(4) nm,b=1.77151(8) nm,c=1.8385(2) nm,α=β=γ=90°,V=2.6324(2) nm³,Z=4,D_c=1.310 g/nm³,μ(MoKα)=9.92 cm^-1,F(000)=1080,R₁=0.0472,wR₂=0.1341。 中心锡原子与环己基碳原子和氧原子构成畸型四面体。 对其结构进行量子化学从头计算,探讨了配合物的稳定性、分子轨道能量以及一些前沿分子轨道的组成特征。 研究了配合物的热稳定性、电化学性能、圆二色谱和体外抗癌活性。     

新型L-苯丙氨酸桥联双卟啉的合成与光谱表征

用L-苯丙氨酸和5-[对-(4-溴丁氧基、己氧基、辛氧基)苯基]-10,15,20-三苯基卟啉合成3种新型L-苯丙氨酸桥联双卟啉,并通过质谱、¹H核磁共振谱、元素分析、红外光谱、紫外光谱对其结构进行了表征。测试并研究了它们在4 000~400 cm^-1范围内的傅里叶变换红外光谱,对主要谱带进行了经验归属。     

L-苏糖酸锰的制备及标准生成焓

The pink powder of manganese L-threonate was obtained by extracting with alcohol the concentrated solution derived from the reaction between L-threonic acid solution prepared by double decomposition reaction of calcium L-threonate with oxalic acid and superfluous manganese oxide at 80℃ for certain time. The composition of the new compound was determined by chemical and elemental analyses and its formula fits Mn(C₄H₇O₅)₂·H₂O, the IR spectra indicated that Mn²⁺ in the compound coordinates to oxygen atom of the carboxyl group, while the proton of the carboxyl group is dissociated, it was assumed that the coordination number of Mn²⁺ was 4. The results of TG-DTG showed that the compound have fairish stability, the intermediate and final product of the thermal de-composition of the compound are Mn(C₄H₇O₅)₂ and MnO₂, respectively. The constant volume combustion energy of the compound, Δ_cE, were determined by a precise rotating-bomb calorimeter at 298.15K, it was (-3384.30±1.21)kJ·mol^-1, its standard enthalpy of Combustion,Δ_cH_m^?,and standard enthalpy of formation,Δ_fH_m^? , were calculated. They are (-3383.07±1.21)kJ·mol^-1 and (-2 571.68±1.63)kJ·mol^-1, respectively.     

Method to evaluate empirical photoionisation cross-sections for L3 magnetic sub-states

A method to evaluate empirical values of L3 magnetic sub-state photoionisation cross-sections has been reported. Preliminarily, the method requires scanning of the existing experimental data on L X-ray fluorescence (XRF) cross-sections for energy dependence of L/Lℓ cross-section ratio. After assuring the energy dependence of L/Lℓ cross-section ratio, the ratio is used for the determination of the alignment parameter A2. Thus, the determined A2 value, along with the available data on the sub-shell photoionisation cross-sections σ_Li and the Coster–Kronig transition probabilities f_ij, is used to evaluate magnetic sub-state photoionisation cross-sections σ_Li(m) for and . The method has been used to evaluate L3 magnetic sub-state photoionisation cross-sections for four elements with Z82, from the measured L XRF cross-sections. To the best of our knowledge, until this date neither theoretical nor semi-empirical data on magnetic sub-state photoionisation cross-sections for these elements has been available, for comparison with such cross-section values and to establish the superiority of one data set over the others.     

meso-四-[4-(Boc-苏氨酸)氨基苯基]卟啉荧光探针对L-色氨酸的痕量测定

利用荧光光谱方法探讨了以对称型pF3N子氨基酸卟啉：11R3S0-四-[4-（Boc-苏氨酸）氨基苯基]卟啉（TAPP—Thr—Boc）作为光谱探针测定三一色氨酸的最佳条件．实验结果表明：双-2-乙基己基硫代琥珀酸钠（AOT）表面活性剂的加入能显著增加体系的灵敏度．在最佳实验条件下,体系荧光强度的下降程度与L-氨酸含量在0．10～8．80μg／mL范围内呈线性关系,检出限为0．034μg/mL方法抗干扰能力强,有较好的选择性和灵敏度,用于实际样品仔猪饲料的测定,结果满意．     

GLC and Colorimetric Methods for the Determination of Capsaicin

Abstract

GLC and colorimetric methods for Capsaicin and its dosage forms are investigated. They offer an improvement in ease, speed and accuracy. The first GLC method is based on the formation of methyl derivative of capsaicin. The colorimetric procedure is based on the formation of O-nitroso-derivative between the drug and sodium nitrite.     

L-半胱氨酸自组装膜诱导草酸钙结晶研究

在CaCl2.H2O和Na2C2O4配制的过饱和溶液中,利用L-半胱氨酸(L-Cys)在金片上形成的自组装膜为模板,研究了草酸钙(CaOxa)在自组装膜上的结晶行为,并探讨了溶液pH对CaOxa晶体组成、晶型及其形貌的影响。采用X射线衍射(XRD)和扫描电子显微镜(SEM)等技术对CaOxa晶体的结构和形貌进行了表征。实验结果表明:当溶液pH=3.0时,溶液中可以形成一水草酸钙(CaC2O4.H2O,COM)和二水草酸钙(CaC2O4.2H2O,COD)晶体,而在同样pH条件下,在L-Cys自组装膜上只形成COD晶体,表明自组装单层对CaOxa晶体的成核和生长有重要影响。通过改变溶液的pH,在自组装单层上可以得到不同晶型和不同形状的CaOxa晶体。当pH=3.0时得到四方块状的COD晶体,而pH=5.0和pH=7.0时分别得到六边形和拉长六边形的COM晶体。     

碳纳米管复合微球修饰L-色氨酸及其对LDL的吸附性能

本文以多孔碳纳米管/活性炭复合微球为载体, 以L-色氨酸为配基, 采用环氧氯丙烷偶联法, 制得修饰L-色氨酸的碳纳米管/活性炭复合微球(L-CNTs/AC)。采用扫描电镜、氮气吸附、傅立叶红外光谱、热分析、X射线光电子能谱等对复合微球进行表征;通过体外静态吸附法对其低密度脂蛋白(LDL)吸附能力进行初步研究。结果表明:环氧氯丙烷偶联法可接枝上L-色氨酸。复合微球中碳纳米管加入量越多, 对LDL的吸附能力越强;当碳纳米管加入量为45wt%时, 对LDL的吸附量达4.623 mg·g^-1, 是未添加碳纳米管的2.3倍多。这是因为碳纳米管不仅可促进复合微球中20~100 nm孔的形成, 而且还可促进复合微球配基修饰量的增多, 从而大大增强了复合微球对LDL的吸附能力。此复合微球可望开发成一种新型的血液灌流LDL吸附剂。