Isomers Trans Research Articles

Effects of trans- and cis-resveratrol on Ca 2+ handling in A7r5 vascular myocytes

Although the natural polyphenol resveratrol posses a direct vasorelaxant effect, its effects on cytoplasmic Ca 2+ concentration ([Ca 2+] i) in vascular cells remain still unclear. Here, we have investigated the effects of the isomers trans- and cis-resveratrol on agonist- and high-K +-induced [Ca 2+] i increases and on voltage-activated transmembrane Ca 2+ fluxes using imaging and patch-clamp techniques in vascular A7r5 myocytes. Arginine vasopressin (AVP) or angiotensin II caused a biphasic increase in [Ca 2+] i that was reduced by preincubation with trans-resveratrol and cis-resveratrol. Both isomers also reduced the agonist-induced increase in [Ca 2+] i in absence of extracellular Ca 2+. In high-K + Ca 2+-free solution, reintroduction of Ca 2+ caused a sustained rise in [Ca 2+] i that was reduced by preincubation with trans-resveratrol or cis-resveratrol. When the isomers were applied during the plateau phase of the agonist- or the high-K +-induced response, a biphasic change in [Ca 2+] i was observed: a transient reduction of the plateau (< 5 min) followed by an increase (> 10 min). Finally, trans-resveratrol and cis-resveratrol inhibited voltage-dependent L-type Ca 2+ currents ( I Ca(L)). In conclusion, resveratrol isomers exert a dual effect on [Ca 2+] i handling in A7r5 myocytes: 1) a blockade of I Ca(L) and 2) an increase in [Ca 2+] i by depletion of intracellular Ca 2+ stores (which interferes with the agonist-induced release of intracellular Ca 2+) and influx of Ca 2+, mainly due to activation of capacitative Ca 2+ entry, although other Ca 2+-permeable channels are also involved. Taken together, these effects may explain, in part, the endothelium-independent vasorelaxant effects of resveratrol in rat aorta.

Rydberg spectra of cis -1,2-dibromoethylene

(2 + 1) resonance enhanced multiphoton ionization (REMPI) spectra of jet-cooled 1,2-dibromoethylene (DBE) are reported for the first time. The spectra are complex because a natural sample contains approximately equimolar amounts of its two geometrical isomers (cis and trans), which have different Rydberg transitions. To this end the geometric isomers were separated by gas chromatography prior to recording REMPI spectra. Preliminary results for the cis-isomer are given. The vibronic assignments made here are consistent with a qualitative molecular orbital description of the electronic structures of the molecule.

Effect of level of linseed on fatty acid composition of muscles and adipose tissues of lambs with emphasis on trans fatty acids

The effects of linseed content in concentrates on the fatty acid (FA) composition of adipose tissues and muscles of lambs were studied in a 2 × 4 design: males (M) vs. females (F) and linseed content (0%, L0, 3%, L3, 6%, L6, 9%, L9). FA proportions were determined both on a DB-wax and on a CP-Sil column in perirenal (PR), dorsal subcutaneous (SC) adipose tissue and in longissusmus dorsi muscle (IM). No effects of linseed contents in the diet on growth performances either in male or female lambs were observed. Linseed supplementation tended to decrease the fatness score. The proportion of linolenic acid increased linearly with the linseed content in the diet, from: 0.6, 0.5, and 0.5% for L0 to 1.9, 1.6, and 1.3% for L9, in PR, SC and IM, respectively. The increase in n − 3 PUFA and in total PUFA was similar to that of linolenic acid. The n − 6: n − 3 ratio decreased from 5.7, 5.3 and 5.8 for L0 to 1.8, 1.7 and 2.7 for L9, in PR, SC and IM, respectively. There was no change in the proportion of docosahexaenoic acid with linseed supplementation. The proportions of C18:1 trans-10 and C18:1 trans-11 did not vary in PR, SC and IM with linseed supplementation. The total proportion of trans-octadecenoic acid was high in each tissue type and group of lambs. C18:1 trans-10 represented about half of the total trans-octadecenoic isomers. With an increase in linolenic acid, most cis- and trans-octadecenoic isomers also increased, but trans-10 and trans-11 isomers did not and cis-9 and cis-11 isomers decreased. With linseed supplementation there was a decrease in the Δ9 desaturase indices in SC.

Synthesis and DFT Defined trans(O5O6) Molecular Structure of Cs[Fe(1,3-pddadp)] · 2H2O. Strain Analysis and Spectral Assignment of the Complex

An iron(III) complex with the hexadentate ligand 1,3-propanediamine-N,N′-diacetate-N,N′-di-3-propionate (1,3-pddadp) was prepared, chromatographically isolated as its isomer trans(O5O6)-Cs[Fe(1,3-pddadp)] · 2H2O, and characterized. The trans(O5O6) configuration of the iron(III) compound was found to dominate and this geometry was established by means of IR spectroscopy and Density Functional Theory (DFT). Structural data correlating the octahedral geometry of the [Fe(1,3-pddadp)]− unit and an extensive strain analysis are discussed in relation to the information obtained for similar complexes. Antibacterial activities of the free ligand and its corresponding iron(III) complex towards common Gram-negative and Gram-positive bacteria are reported as well.

Corn oil supplementation to steers grazing endophyte-free tall fescue. II. Effects on longissimus muscle and subcutaneous adipose fatty acid composition and stearoyl-CoA desaturase activity and expression

Eighteen steers were used to evaluate the effect of supplemental corn oil level to steers grazing endophyte-free tall fescue on fatty acid composition of LM, stearoyl CoA desaturase (SCD) activity and expression as well as cellularity in s.c. adipose. Corn oil was supplemented (g/kg of BW) at 0 (none), 0.75 (medium), and 1.5 (high). Cottonseed hulls were used as a carrier for the corn oil and were supplemented according to pasture availability (0.7 to 1% of BW). Steers were finished on a rotationally grazed, tall fescue pasture for 116 d. Fatty acid composition of LM, s.c. adipose, and diet was determined by GLC. Total linoleic acid intake increased linearly (P < 0.01) with corn oil supplementation (90.7, 265.1, and 406.7 g in none, medium, and high, respectively). Oil supplementation linearly reduced (P < 0.05) myristic, palmitic, and linolenic acid percentage in LM and s.c. adipose. Vaccenic acid (C18:1 t11; VA) percentage was 46 and 32% greater (linear, P = 0.02; quadratic, P = 0.01) for medium and high, respectively, than none, regardless of tissue. Effect of oil supplementation on CLA cis-9, trans-11 was affected by type of adipose tissue (P < 0.01). In the LM, CLA cis-9, trans-11 isomer was 25% greater for medium than for none and intermediate for high, whereas CLA cis-9, trans-11 CLA isomer was 48 and 33% greater in s.c. adipose tissue for medium and high than for none, respectively. Corn oil linearly increased (P </= 0.01) trans-10 octadecenoic acid and CLA trans-10, cis-12; however, values were low (<0.35 and <0.035% of total fatty acids, respectively). Oil supplementation did not change (P > 0.05) the percentage of total SFA, MUFA, or PUFA but linearly increased (P = 0.03) n-6:n-3 ratio from 2.4 to 2.9 in none and high, respectively. Among tissues, total SFA and MUFA were greater in s.c. adipose than LM, whereas total PUFA, n-6, and n-3 fatty acids and the n-6:n-3 ratio were lower. Trans-10 octadecenoic acid, VA, and CLA trans-10, cis-12 were greater (P < 0.01) in s.c. adipose than in LM. Oil supplementation did not alter (P > 0.05) stearoyl CoA desaturase activity or mRNA expression. Corn oil supplementation to grazing steers reduced the percentages of highly atherogenic fatty acids (myristic and palmitic acids) and increased the percentages of antiatherogenic and anticarcinogenic fatty acids (VA and cis-9, trans-11 CLA).

Determination of 77Se—77Se and 77Se—13C J‐Coupling Parameters for the Clusters [Re5OsSe8(CN)6]3‐ and [Re4Os2Se8(CN)6]2‐.

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Accumulation of biohydrogenation intermediates during in vitro ruminal fermentation of camelina oil-based rations

The myriad putative health benefits of conjugated linoleic acid (CLA) and in particular the cis-9, trans-11 isomer, have stimulated interest in increasing its concentration in food. Ruminant fat is the main dietary source of CLA for humans and CLA is produced in the rumen by incomplete biohydrogenation of dietary linoleic acid (LA). It is now accepted that most CLA is synthesised post-ruminally by desaturation of vaccenic acid (VA) produced during ruminal biohydrogenation of (LA) and linolenic acid (LNA) (Griinari et al., 2000). Enhancement of VA synthesis in the rumen is therefore an important element of strategies to increase CLA concentration in tissue. The objective of this experiment was to determine the effect of controlling the rate of release of oil from camelina seeds, a novel source of both LA and LNA, on the accumulation of intermediates during ruminal biohydrogenation.

Effects of supplemental rumen-protected conjugated linoleic acid or corn oil on lipid content and palatability in beef cattle1

Thirty-six Angus x Hereford heifers were used in a 3 x 2 factorial (3 dietary treatments; 2 supplementation times) to examine the effect of dietary lipid supplementation on lipid oxidation, lipid composition, and palatability of ribeye steaks and ground beef. Lipid was supplied in the diets as corn oil or a partially rumen-protected CLA salt for 2 specific treatment periods of the final 32 or 60 d on feed, corresponding to a total time on feed of 89 or 118 d. After an initial 56-d feeding period (basal diet), the heifers were fed 1 of 3 dietary treatments (DM basis): 1) a basal diet containing 88% concentrate and 12% grass hay (CON), 2) the basal diet plus 4% corn oil (OIL), or 3) the basal diet plus 2% partially rumen-protected CLA (RPCLA) containing 31% CLA. Heifers were randomly allotted to dietary treatments at the initiation of the study and fed individually. At 48 h postmortem, the right forequarter of each carcass was fabricated into retail cuts. Steaks (2.54-cm thick) were obtained from the posterior end of the ribeye roll (NAMP 112), and beef trim was ground for all subsequent analyses. Dietary treatment did not affect (P > 0.05) lipid oxidation in ground beef or ribeye steaks. Total trans-octadecenoate fat and trans-10 octadecenoic acid content in ribeye steaks increased (P < 0.05) with RPCLA compared with CON. Total CLA and the cis-9 trans-11 isomer of CLA contents in ribeye steaks were unchanged (P > 0.05) by lipid supplementation. In ground beef, RPCLA supplementation increased (P < 0.05) the amount of trans fat and trans-10 octadecenoic acid compared with CON or OIL; supplementation of RPCLA increased (P < 0.05) the amount of CLA cis-9 trans-11 isomer and total CLA. Lipid supplementation did not alter (P > 0.05) off-flavor ratings in ground beef or ribeye steaks. Supplementation of corn oil increased (P < 0.05) total PUFA content of ribeye steaks compared with CON and RPCLA. Dietary RPCLA supplementation increased the amount of trans fat per serving (85.5 g, broiled) by 110 and 88% in ribeye steak and ground beef, respectively, and CLA cis-9 trans-11 by 58% in ground beef compared with CON. Supplementing OIL or RPCLA resulted in minimal changes in lipid oxidation and sensory attributes of steaks and ground beef.

Conjugated Linoleic Acids Promote Human Fat Cell Apoptosis

Conjugated linoleic acids (CLAs) are conjugated dienoic isomers of linoleic acid. Some isomers have been shown to reduce fat mass in animal and cell culture models. However, controversial results were obtained in studies of supplementation of CLAs in human subjects. In order to get more insights into the direct effects of CLAs on human fat cells, we have studied the influence of cis-9, trans-11 CLA and trans-10, cis-12 CLA on the biology of human SGBS preadipocytes and adipocytes. Both CLA isomers equally inhibited the proliferation of preadipocytes in a dose-dependent manner. Continuous treatment with 1-10 microM trans-10, cis-12 CLA, and to a weaker extent cis-9, trans-11 CLA, inhibited accumulation of lipids during adipogenic differentiation. Treatment with higher doses of CLA induced apoptosis in preadipocytes, in differentiating cells, and adipocytes. The trans-10, cis-12 isomer had a higher apoptotic potency in adipocytes than cis-9, trans-11 CLA. Taken together, the treatment of human preadipocytes and adipocytes with physiological relevant concentrations of CLAs resulted in an impairment of proliferation and differentiation and induction of apoptosis. The trans-10, cis-12 isomer was more potent than the cis-9, trans-11 isomer. Further clinical studies are needed to evaluate the effects of CLAs on human fat mass and metabolism in vivo.

Azorean bovine milk conjugated linoleic acid. Effect of green pasture diet, storage and processing temperature

Conjugated linoleic acids (CLA) that are isomeric forms of the cis-9,cis-12 linoleic acid have sparked considerable interest in the scientific community due to their reported beneficial health properties. The objective of this study was the quantification of the CLA in commercial Azo- rean bovine milk and comparison with CLA in Portuguese mainland milk, and evaluation of the effect of storage and the processing temperature on the CLA content in milk. The relative average of CLA (cis-9,trans-11 isomer) content in Azorean (S. Miguel Island-Portugal) and Portuguese mainland milks represents 1.33 ± 0.09% and 0.79 ± 0.07% of total fatty acid methyl esters (tFAME), respectively. The cis-9,trans-11-CLA isomer variation in Azorean ultrapasteurized (UHT) milk, throughout the year, ranged from 1.16 ± 0.09% to 1.46 ± 0.09% and reflects the bovine pasture-fed diet (fresh grass) during all seasons and the mild winter in the Azores Islands. The CLA content of Azorean milk is a little higher than that published in the literature for New Zealand (1.20% of tFAME). The effect of the processing temperature on the CLA level shows a decrease in the cis- 9,trans-11-CLA isomer content from 1.56 ± 0.05 (raw milk) to 1.40 ± 0.04 and 1.26 ± 0.04 (% to tFAME) in different pasteurized and UHT-treated milks, respectively. The effect of storage time on the CLA content of commercial UHT milk, kept refrigerated at 6-7 oC for two months, shows a loss of 1.2%, which is negligible compared with the processing temperature effect. Azorean milk is natu- rally rich in CLA, and according to recently published literature, has a wide array of health benefits and may be useful in the prevention of some degenerative diseases. milk / fatty acid / conjugated linoleic acid / gas chromatography

Conjugated linoleic acid in diets for large-size rainbow trout (Oncorhynchus mykiss): effects on growth, chemical composition and sensory attributes

The effects of graded levels (0 %, 0.5 %, 0.75 and 1 %) of dietary conjugated linoleic acid (CLA) were assessed on 97 g rainbow trout. Fish were fed to satiation twice a day for 12 weeks. At the end of the experiment, all groups of fish weighed more than 250 g and no significant differences were detected in growth performance, feed conversion, nutrient or energy utilisation or body composition between treatments. A decrease in liver lipid content resulted from including CLA and was accompanied by a reduction in malic enzyme activity. The muscle saturated acid and PUFA content did not vary between dietary treatments, despite the increasing concentration of stearic acid and CLA. In the liver, however, both fractions increased significantly with dietary CLA. Moreover, the MUFA decreased significantly in both muscle and liver. CLA was incorporated into tissue lipids, with levels in flesh (2.1-4.2 %) being 2-fold higher than in liver (0.8-1.9 %). In muscle, the percentage of cis-9, trans-11 isomer ranged from 39.5 % to 41.8 % and that of trans-10, cis-12 isomer from 31.4 % to 33.4 % of total CLA. The incorporation of CLA isomers in the liver varied with dietary treatment, and the cis-9, trans-11 isomer seemed to be more efficiently incorporated than trans-10, cis-12. Sensory data indicated slight-to-moderate differences between the trout fed with and without CLA. The present results suggest that 250 g rainbow trout can incorporate CLA in both muscle and liver, contributing to the production of a functional food.

Determination of 77Se−77Se and 77Se−13C J-Coupling Parameters for the Clusters [Re5OsSe8(CN)6]3- and [Re4Os2Se8(CN)6]2-

We have investigated rarely observed 77Se J-couplings (spin-spin couplings) in the mixed-metal face-capped octahedral clusters [Re5OsSe8(CN)6]3- and [Re4Os2Se8(CN)6]2- at natural abundance. To the best of our knowledge, these are the first observations of Se-Se spin-spin interactions between mu3-Se sites, important for stereochemical assignments in hexarhenium analogues, Chevrel phase materials, and similar cluster materials. NMR techniques such as COSY, INADEQUATE, and 2D J-resolved spectroscopy have been used in conjunction to study these interactions. The two isomers (cis and trans) of [Re4Os2Se8(CN)6]2- were distinguishable, and selective isotopic labeling of [Re5OsSe8(CN)6]3- with 13CN ligands enabled resonances to be assigned by observing the 2J (Se-M-C) couplings. For [Re5OsSe8(CN)6]3-, two different 2J (Se-M-Se) couplings were measurable on a single cluster, and these are related to one another through spin-spin interactions across a face diagonal or along an edge of the cube of inner selenium ligands. A rigorous analysis based on combinatorial math has been invoked to assign the couplings on the basis of the probability of multiple-spin interactions. The face diagonal association is found to result in a J-coupling interaction larger in magnitude than that from coupling along an edge of the cube-information critical for making stereochemical assignments of selenium sites.

The QuaLAT project: mapping QTL for milk fatty acid content in the Italian Brown population and in the Israel Holstein Friesian

Milk contains a number of micro-components (“functional foods”) having specific health promoting activities. Important among these compounds are the conjugated linoleic acids (CLAs) consistingof a mixture of isomers of C18:2 fatty acid with conjugated doublebonds. The predominant form in milk fat is the cis-9,trans-11 isomer, accounting for 75 to 90% of the total CLA content. Biomedical studies with animal models have demonstrated a variety of preventive health effects from CLA including anticarcinogenic, antiatherogenic, antiobesity, immune system enhancement and antidiabetic benefits. Linolenic acid does not form CLA as an intermediate in rumen biohydrogenation, but it does form vaccenic acid (C18:1,t11) that enters the bloodstream from the rumen, through the abomasum and intestine, and is transported to the mammary gland. Several investigations using direct and indirect approaches established that endogenous synthesis of CLA via ∆9-desaturase action on vaccenic acid (VA, C18:1,t11) is the predominant source of the CLA found in milk fat across a range of diets. Thus, rumen VA production and mammary tissue ∆9-desaturase (D9D) are of key importance in determining the CLA content of milk fat. Mammary tissue D9D activity is measured indirectly as the milk desaturase index (DI), calculated as the ratio of milk CLA to the sum of milk CLA and VA. The study is centered on the Italian Brown Swiss and Israeli Holstein dairy cattle populations. Objectives of the project are: i) to identify environmental and physiological factors (e.g., herd, season, parity and stage of lactation) affecting milk CLA content and DI, and determine appropriate correction factors, if needed; ii) to estimate heritability of milk CLA content and DI in the study populations; iii) to implement a total genome scan for QTL affecting milk CLA VA content and DI in the two study populations. using a selective DNA pooling approach based on milk samples for the initial scan, followed by individual genotyping to confirm suggestive QTL regions. For each of the studied populations,, the research includes determination of CLA, VA and DI for more than 2500 individuals of five large sire half-sib families (for the genome scan) and an additional 400 individuals of 20 small sire half-sib families for the heritability analysis. Milk fat is extracted and transmethylated according to Chouinard et al. (1999). Fatty acid methyl esters are analyzed by GC-FID with a highly polar 100 m SP-2560 column, using GLC-60 supplemented with CLA and VA as a standard. Based on the results obtained to date for the Italian Brown Swiss population, the mean (fatty acid composition over the total fatty acid) ±SD( minimum and maximum) are respectively: VA, 1.97±0.77 (0.63 - 5.40); CLA, 0.63±.0.47 (0.35 - 5.31); DI, 0.25±0.097 (0.063 - 0.64). The means for VA and CLA content found are similar to those reported by other studies (control treatment) and reviewed by Collomb et al (2006). The slightly larger variability here reported, anyhow within the limit of values found in literature, is possibly affected by the wide farming conditions of the individuals sampled.

ISA 247

ISA 247

Ligand steric effect on the coordination mode of nitrite ion: Syntheses and X-ray single crystal structures of trans-[NiL 2(ONO) 2] and cis-[NiL′ 2(O 2N)](NO 2)·H 2O [L = 2-(aminomethyl)pyridine and L′ = (2-aminoethyl)pyridine

The steric effects of the co-ligands originated from the pi-cloud of the pyridine moiety and from increased aliphatic chain length have been utilized to synthesize two different binding modes of nitrite ion. A red-violet nitrito isomer trans-[NiL 2(ONO) 2] ( 1) and a blue-violet nitrito (O,O) isomer cis-[NiL′ 2(O 2N)](NO 2)·H 2O ( 2) are obtained by adding L and L′ to the methanolic suspension of K 4[Ni(NO 2) 6]·H 2O [L = 2-(aminomethyl)pyridine and L′ = 2-(aminoethyl)pyridine]. No other isomer of complex 1 or 2 is yielded in solution irrespective of the nature of the solvent used or in the solid state. They have been characterized by routine physicochemical studies as well as by X-ray single crystal structure analysis.

Local Order in Fully Deuterated Liquid N-Methylacetamide (C3D7NO) As Studied by Neutron Diffraction and Density-Functional Theory Calculations

A structural investigation of fully deuterated liquid N-methylacetmide (NMAd7) is performed at 308 K and atmospheric pressure by using neutron diffraction together with density-functional theory (DFT). The analysis of experimental data yields the total structure factor SM(Q), the molecular form factor F1(Q), and the distinct pair correlation function gL(r). The DFT calculations are performed to study the relative stability of the two possible isomers (trans and cis) and to examine some possible clusters recently published that may describe the intermolecular arrangement in the liquid state. Neutron measurements can be interpreted in terms of trans linear trimer (T1) and cis cyclic trimer (T2) where the total number of hydrogen bonds is respectively equal to two and three. The theoretical structure factors obtained on the basis of intermolecular arrangements agree fairly well with the experimental one beyond Q = 2 A-1. All through the study, a comparison is made with complementary X-ray results.

Dietary conjugated linoleic acid has limited effects on tissue protein anabolism in sedentary and exercising adult rats

The effects of conjugated linoleic acid isomers (CLA) and endurance training on lean body mass are expected to result from their action on tissue protein metabolism. The aim of this study was to analyze their effects on protein metabolism in 2 muscles, the small intestine and liver of adult rats. Four-month-old male Wistar rats were fed diets containing either no CLA, cis-9, trans-11 CLA isomer (1 g.100 g(-1)), trans-10, cis-12 CLA isomer (1 g.100 g(-1)) or both isomers (1 g.100 g(-1) each) for 6 weeks. Half of the rats were subjected to endurance training by running on a treadmill. At the end of this period, the rats were injected with a flooding dose of (13)C-valine to determine protein synthesis rates in the post-absorptive (experiment 1) and in the post-prandial (experiment 2) states. No effect of CLA or endurance training were detected in the small intestine. Training reduced food intake and protein synthesis rates in the liver but no effect was found on the protein synthesis rates in muscles. In the post-absorptive state, protein synthesis rate was increased by feeding the trans-10, cis-12 CLA isomer alone in the liver (+9%) or in combination with the cis-9, trans-11 isomer in the gastrocnemius (+30%), mostly in sedentary rats. In the post-prandial state, the cis-9, trans-11 CLA isomer tended to reduce the protein synthesis rate in the gastrocnemius muscle. However, no effect of CLA was found on muscle protein amounts. In conclusion, CLA isomers would have limited but differential effects on tissue protein metabolism in adult rats.

Kinetics of the Oxidation of L-Cysteine by trans- and cis-Cobalt(III) and Iron(III) Complexes

Kinetics of oxidation of L-cysteine by pairs of trans and racemic cis isomers of cobalt(III) and iron(III) based transition metal complexes have been studied in aqueous solution. Kinetics measurements were run under pseudo first order conditions in which the concentration of cysteine is between one and two orders of magnitude greater than that of the isomers of the transition metal complex. The orders of the reaction with respect to both cysteine and the isomer were determined. The observed rate constants and the overall rate constants of the oxidation process were measured. For all geometrical isomers, it was found that the rate constant of oxidation of L-cysteine by the trans isomer is between one to three orders of magnitude greater than that by the cis isomer. The difference in rates can be explained by a geometric factor around the metal ion center in the complex. The less crowded isomer (trans) makes electron transfer easier and hence facilitates the oxidation process which leads to a higher oxidation rate.

Influence of the position of substituents in the cytotoxic activity of trans platinum complexes with hydroxymethyl pyridines

The synthesis and chemical characterization of two trans platinum complexes, ( 1) trans-[PtCl 2NH 3(2-hydroxymethylpyridine)] and ( 2) trans-[PtCl 2NH 3(3-hydroxymethylpyridine)], are described. The structures and chemical behaviour of these compounds have been compared to those of their isomer ( 3) trans-[PtCl 2NH 3(4-hydroxymethylpyridine)] previously studied. X-ray structures of all of them were solved and some interesting differences were found. The values of the dihedral angle (85°, 57° and 42° for 1, 2 and 3, respectively) demonstrate how important is the position of substituent from a structural point of view. Studies of circular dichroism (CD), electrophoretic mobility (EM) in agarose gel and atomic force microscopy (AFM) showed differences in the modifications caused by the three complexes on DNA. Studies of antiproliferative activity of complexes 1 and 2 against cell tumour lines (HL-60) and apoptosis assays have also been carried out, showing that 1 as well as 2 are far less active than the previously described complex 3 (IC 50 = 19; 19 and 3 μM, respectively). This fact probes that slight modifications on the drug’s design may generate significant differences in the final antitumour activity by modifying the DNA–drug adducts, performance of resistance mechanisms and all the factors that play a fundamental role in Pt complexes’ cytotoxicity.

The effect of 6 months supplementation with conjugated linoleic acid on insulin resistance in overweight and obese

Contradicting results have been published regarding the effect of conjugated linoleic acid (CLA) on insulin resistance. However, only a few studies have used the euglycemic hyperinsulinemic clamp method, which is considered the standard for measuring insulin resistance. To evaluate if CLA as a mixture of the main isomers trans-10 cis-12 and cis-9 trans-11 affects the insulin resistance in healthy overweight and obese male and female adults. The main study was a randomized, double-blind, placebo-controlled trial with change in body composition as primary end point comprising 118 subjects receiving supplementation with either placebo (olive oil) or CLA (Clarinol) for 6 months. A sub-population of 49 subjects agreed additionally to participate in an euglycemic hyperinsulinemic clamp study at baseline and after 6 months of supplementation with study drug. The primary outcome was the change in glucose uptake (M) as measured by the hyperinsulinemic euglycemic glucose clamp method. Secondary outcomes were the correlates between insulin resistance and changes in body composition or blood chemistry parameters. Forty-one subjects completed the clamp test at both time points. The median M of the CLA group was 11.0 mg min(-1) lean body mass (lbm)(-1) (n=24) at baseline, 10.3 mg min(-1) lbm(-1) (n=24) after 6 months, and the median difference was +0.21 mg min(-1) lbm(-1) (n=24). The median M of placebo group was 8.4 mg min(-1) lbm(-1) at baseline and 9.3 mg min(-1) lbm(-1) after 6 months and the median difference was -0.22 mg min(-1) lbm(-1) (n=17). No significant (P<0.05) differences were found within groups or between groups. Likewise, the glucose uptake insulin concentration ratio during clamp (M/I) was independent of treatment and time. Homeostasis model assessment (HOMA) and quantitative insulin sensitivity check index derived from fasting glucose and insulin were also independent of treatment and time, and HOMA for the clamp population (n=49) corresponded well with HOMA for the per protocol population (n=83). Correlation analysis showed that changes in M were inversely correlated to changes in glucohemoglobin (P=0.002), but did not correlate with changes in either glucose, insulin, insulin c-peptide, leptin, adiponectin or percent body fat. CLA does not affect glucose metabolism or insulin sensitivity in a population of overweight or obese volunteers.