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PubMed1986

The development of cyclic motility in fetuses of diabetic mothers.

The cyclic organization of spontaneous movement was studied longitudinally in 22 fetuses of diabetic mothers (FDMs) during the third trimester of gestation and quantified with spectral analysis. Cyclic motility at frequencies between .08 and 1.22 cycles/min was found in all fetuses, although it was temporarily absent in 12 of the 22 fetuses at some time between 25 and 38 weeks. While some parameters of cyclic motility changed little, the frequency of the dominant motility cycle doubled from .24 to .48 cycle/min between 28 and 36 weeks, and the relative strength of motility cycles in the band between .18 and 1.02 cycles/min decreased temporarily at 36 weeks. These developmental changes and the common absence of cyclic motility contrast sharply with previous findings in normal fetuses, and (except for its absence) are accounted for by a subgroup of FDMs whose mothers' blood glucose levels were least well controlled during the third trimester of gestation. The presence of cyclic motility in all FDMs provides further evidence that cyclic activation is a basic property of the developing central nervous system in the human, as it appears to be in other vertebrates. However, the differences between FDMs and normal fetuses suggest that the development of cyclic motility is sensitive to disturbances in the fetal metabolic environment.

Birth Weight↗
PubMed1989

[Prostaglandin E2 receptor and GTP binding protein in the normal and nephrotic rat kidney].

The relationship between prostaglandin E2 (PGE2) receptor and GTP binding protein was studied in the normal and aminonucleoside-induced nephrotic rats. Affinities and maximal binding sites of PGE2 receptors in renal medulla of the male Wistar rats were examined by Scatchard analysis. Cyclic AMP and inositol phosphates were measured in the medulla tissues to examine the intracellular mediators of PGE2 receptor activation. The following results were obtained: 1) GTP gamma S, a nonhydrolyzable guanine nucleotide, increased the 3H-PGE2 binding in a concentration-dependent manner, and pertussis toxin partially attenuated the GTP gamma S effect, 2) PGE2 stimulated the accumulation of inositol phosphates in the medullary tissues with a similar dissociation constant (Kd) value of binding analysis, and high concentrations of PGE2 stimulated the accumulation of cyclic AMP, 3) the affinity of PGE2 receptors in the renal cellular membranes taken from nephrotic rats were significantly lower than that in normal rats, and the effects of GTP gamma S on the affinity was greater in nephrotic rat kidney than normal one. These results suggest that PGE2 receptor of the rat kidney links to a GTP binding protein. In nephrotic rat kidney, damages occur not only in PGE2 receptor but also in the GTP binding protein.

Animals↗
PubMed2002

Cyclic mechanical stretch induces VEGF and FGF-2 expression in pulmonary vascular smooth muscle cells.

Vascular endothelial growth factor (VEGF) and basic (b) fibroblast growth factor (FGF-2/bFGF) are involved in vascular development and angiogenesis. Pulmonary artery smooth muscle cells express VEGF and FGF-2 and are subjected to mechanical forces during pulsatile blood flow. The effect of stretch on growth factor expression in these cells is not well characterized. We investigated the effect of cyclic stretch on the expression of VEGF and FGF-2 in ovine pulmonary artery smooth muscle cells. Primary confluent cells from 6-wk-old lambs were cultured on flexible silicon membranes and subjected to cyclic biaxial stretch (1 Hz; 5-25% stretch; 4-48 h). Nonstretched cells served as controls. Expression of VEGF and FGF-2 was determined by Northern blot analysis. Cyclic stretch induced expression of both VEGF and FGF-2 mRNA in a time- and amplitude-dependent manner. Maximum expression was found at 24 h and 15% stretch (VEGF: 1.8-fold; FGF-2: 1.9-fold). These results demonstrate that mechanical stretch regulates VEGF and FGF-2 gene expression, which could play a role in pulmonary vascular development or in postnatal pulmonary artery function or disease.

Animals↗
PubMed2006

Effects of 17beta-estradiol on growth and apoptosis in human vascular endothelial cells: influence of mechanical strain and tumor necrosis factor-alpha.

Vascular endothelial cell (EC) integrity is key to arterial health; endothelial dysfunction is linked to atherogenesis. Atherosclerosis shows a male preponderance, possibly related to the protective effect of estrogens in women. This study examined the effect of estrogens on growth, apoptosis and adhesion molecule expression in cultured human EC. The effects of 17beta-estradiol (E2) were studied in human umbilical vein endothelial cells (HUVEC) under normal culture conditions, and following exposure to cyclic mechanical strain or tumor necrosis factor alpha (TNFalpha). E2 enhanced HUVEC growth in serum-enriched media, in a concentration-dependent manner. This up-regulation of EC growth by E2 was associated with an increase in telomerase activity, assessed by PCR-based TRAP analysis. Cyclic strain enhanced [(3)H]-thymidine incorporation into DNA, and increased activation of mitogen-activated protein (MAP) kinase ERK1/2 and expression of early growth genes (Egr-1 and Sp-1); E2 attenuated the strain-induced ERK1/2 activation but not the early growth gene expression or DNA synthesis. TNFalpha (20 ng/mL) induced apoptosis in HUVEC, causing a decrease in DNA synthesis, increase in floating and Annexin-V-stained cell numbers, and morphological changes. TNFalpha also upregulated ERK1/2 activity and expression of adhesion molecules (ICAM-1, VCAM-1 and E-selectin). E2 significantly attenuated the effects of TNFalpha on ERK1/2 activity, apoptosis, and E-selectin expression in the cells. Thus, estradiol enhances growth and reduces TNFalpha-induced apoptosis in EC; enhanced EC growth may be mediated via upregulation of telomerase activity. These effects are possible cellular mechanisms underlying female gender-associated cardiovascular protection.

Apoptosis↗
PubMed2002

Identification of mechanically induced genes in human monocytic cells by DNA microarrays.

BACKGROUND: Hypertension is a risk factor for coronary heart disease. Macrophages are critically involved in both atherogenesis and plaque instability. Although macrophages may be subjected to excess mechanical stress in these diseases, the way in which biomechanical forces affect macrophage function remains incompletely defined. OBJECTIVE: To investigate the molecular response to mechanical force in macrophages. DESIGN AND METHODS: We used a DNA microarray with 1056 genes to describe the transcriptional profile of mechanically induced genes in human monocytic THP-1 cells. Mechanical deformation was applied to a thin and transparent membrane on which cells were cultured. After THP-1 cells were pre-incubated in the presence of phorbol 12-myristate 13-acetate (0.2 micromol/l) for 24 h, THP-1 cells attached to the membrane were subjected to biaxial mechanical strain. Interleukin-8 concentrations were determined using an enzyme-linked immunosorbent assay. RESULTS: In DNA microarray analysis, cyclic mechanical strain at 1 Hz induced only three genes more than 2.5-fold at 3 and 6 h in THP-1 cells: prostate apoptosis response-4 (3.0-fold at 3 h, 6.7-fold at 6 h), interleukin-8 (4.3-fold at 6 h) and the immediate-early response gene, IEX-1 (2.6-fold at 6 h). Real-time reverse transcriptase polymerase chain reaction analysis confirmed the amplitude-dependent induction of these three genes. In addition, mechanical strain increased interleukin-8 protein expression. CONCLUSION: The present study demonstrates that human monocytic cells respond to mechanical deformation with induction of immediate-early and inflammatory genes. These findings suggest that mechanical stress in vivo, such as that associated with hypertension, may play an important part in atherogenesis and instability of coronary artery plaques, through biomechanical effects on vascular macrophages.

Apoptosis Regulatory Proteins↗
PubMed1994

Effects of preoperative chemotherapy on DNA ploidy patterns, cell cycle, and histological findings in gastric and colonic cancer patients.

The effects of preoperative chemotherapy on gastric and colonic cancers have yet to be evaluated fully. In this study, its effects were assessed by studying DNA ploidy patterns, cell cycles, and histological findings in such patients. Thirty-nine patients with gastric or colonic cancer were given preoperative chemotherapy with UFT (an admixture of tegafur and uracil). Biopsy specimens for analysis were obtained before chemotherapy through a gastroscope or colonoscope and after chemotherapy from resected tumors. The DNA ploidy patterns and cell cycles were evaluated using a flow cytometer and the tissues were examined histologically. The DNA ploidy pattern was diploid (D) in 12 gastric and 13 colonic cancer patients and aneuploid (A) in 10 and 4 patients, respectively. After chemotherapy, the pattern changed in nine gastric (A-->D: 7, D-->A: 2) and six colonic cancer patients (A-->D: 3, D-->A: 3) and was unchanged in the remaining patients. Cell cyclic analysis showed decreased G1- and increased S-phase fractions in 10 of 12 patients with gastric and 6 of 10 patients with colonic cancer. Histologically, decreased tumor cellularity, increased fibrosis, and/or cytological changes were observed in both cancers after chemotherapy. Gastric and colonic cancers in which the DNA ploidy pattern changed from aneuploid to diploid, G1- decreased and S-phase increased, and/or histological changes were observed, were considered to have responded to preoperative UFT administration.

Adult↗
PubMed2005

Genotyping single-nucleotide polymorphisms by minisequencing using tag arrays.

The need for large-scale and high-throughput methods for SNP genotyping has rapidly increased during the last decade. Our system, presented here, combines the highly specific genotyping principle of minisequencing with the advantages of a microarray format that allows highly multiplexed and parallel analysis. Cyclic minisequencing reactions with fluorescently labeled dideoxynucleotides (ddNTPs) are performed in solution using multiplex PCR product as template and detection primers, designed to anneal immediately adjacent and upstream of the SNP site. The detection primers carry unique 5' tag sequences and oligonucleotides complementary to the tag sequence, cTags, are immobilized on a microarray. After extension, the tagged detection primers are allowed to hybridize to the cTags; then the fluorescent signals from the array are measured, and the genotypes are deduced according to the label incorporated. The "array of arrays" format of the system, accomplished by a silicon rubber grid giving separate reaction chambers, allows either 80 or 14 samples to be analyzed for up to 200 or 600 SNPs, respectively, on a single microscope slide.

Genotype↗
PubMed2004

Novel CuIII bis-1,2-dichalcogenene complexes with tunable 3D framework through alkaline cation coordination: a structural and theoretical study.

The deprotonated form of the ligands pyrazine-2,3-diselenol (pds) and pyrazine-2,3-dithiol (pdt) react with Cu(ClO(4))(2).6 H(2)O to form different Cu(III) complexes Na[Cu(III)(pds)(2)].2 H(2)O (1), Li[Cu(III)(pds)(2)].3 H(2)O (2), and Na[Cu(III)(pdt)(2)].2 H(2)O (4) depending on the countercation compound used as deprotonating agent (NaOH, LiOH). Two other Cu(III) complexes were obtained by replacement of the alkali metal cations with tetrabutylammonium (TBA(+)), namely, TBA[Cu(III)(pds)(2)] (3), and TBA[Cu(III)(pdt)(2)] (5). All complexes were characterized by (1)H and (13)C NMR and IR spectroscopy, electronic absorption, elemental analysis, cyclic voltammetry (CV), and X-ray crystallography. Electrical conductivity measurements on single crystals show that these salts exhibit insulating behavior. The crystal structure of these species revealed a lateral coordination capability of the N atoms of the pyrazine ring of both pds and pdt ligands towards the alkali metal ions, which leads to the build up of a net of coordinative bonds, hydrogen bonds, and contacts that result in the final 3D structure. Two parameters control the crystal engineering of the final 3D structures: the nature of the alkali metal countercation and the nature of the chalcogen atom (Se/S), which allow fine-tuning of complex 3D crystal lattice. Density functional calculations were performed on the [Cu(pds)(2)] and [Cu(pdt)(2)] systems to investigate the electronic structure of the complexes and understand their electronic and electrochemical behavior by studying the frontier molecular orbitals. This study also reveals whether the redox processes take place on the ligands or on the metal center, a question under continuous discussion in the literature.

Alkalies↗
PubMed2005

Intramolecular hydrogen-bond-assisted planarization of asymmetrically functionalized alternating phenylene-pyridinylene copolymers.

We report on the synthesis and characterization of a series of asymmetrically functionalized amphiphilic polymers with alternating pi-donor units (e.g., substituted benzene) and pi-acceptor units (e.g., pyridine) along the polymer backbone. The purpose of our present work involves incorporation of functional groups along the main chain to form intrachain hydrogen bonds, which promote planarization of the polymer backbone, and to fine-tune the optical properties. The structure-property relationship of polymers P1-P6 was investigated by means of analytical methods, such as FTIR spectroscopy, 1H and 13C NMR spectroscopy, UV/Vis spectroscopy, fluorescence spectroscopy, gel permeation chromatography, thermogravimetric analysis, cyclic voltammetry, and X-ray powder diffraction. All polymers were soluble in common organic solvents, and the optical and fluorescence spectra of the polymers showed significant changes according to the formation (P4, P5) or absence (P6) of intramolecular hydrogen bonding along the polymer backbone. Moreover, the 2,6- or 3,5-linkage of the pyridine rings in P5 and P6, respectively, reduced the conjugation along the polymer backbone and this is reflected in their optical properties. The optical properties of the polymers were influenced by the addition of acid (P1-P6), base (P4-P6), and metal ions (e.g., Cu2+, Fe3+, Ag+, Ni2+, Pd2+, Mn2+, Zn2+, Mg2+, and Pr3+). Such polymers could be used in various applications, including sensors and stimuli-responsive displays.

Journal Article↗
PubMed1989

Seasonal variation in suicide: is there a sex difference?

Seasonal variation in suicide in Italy for the years 1969-81 has been assessed in males and females by means of harmonic analysis. Cyclical fluctuations in the number of suicides, reasonably consistent over the 13 years of the study, have been observed in both sexes. Seasonal harmonics accounted for 65.3 and 48.4% of the variance in male and female suicides respectively. While in males the only important seasonal harmonic was the first (one cycle per year), in females there was an important first harmonic and a second harmonic (two cycles per year). In both sexes the peak of the first harmonic occurred in May, while in females the subsidiary peak occurred in October-November.

Cross-Sectional Studies↗
PubMed2001

Preparation of the octahedral d(6) amido complex TpRu(CO)(PPh(3))(NHPh) (Tp = Hydridotris(pyrazolyl)borate): solid-state structural characterization and reactivity.

The reaction of TpRu(CO)(PPh(3))(OTf) (2) with LiNHPh affords the amido complex TpRu(CO)(PPh(3))(NHPh) (3) in 88% isolated yield. The amido complex 3 has been characterized by (1)H NMR, (13)C NMR, (31)P NMR, elemental analysis, cyclic voltammetry, and a solid-state X-ray diffraction study. Variable temperature NMR studies have revealed a rotational barrier around the ruthenium-amido nitrogen bond of 3 of 12 kcal/mol (transformation of the major isomer to the minor isomer). The solid-state structure of 3 discloses a pyramidal amido moiety. Heating benzene solutions of the amido complex 3 and 1,4-cyclohexadiene or 9,10-dihydroanthracene results in no observable reaction. Reaction of complex 2 with excess aniline yields [TpRu(CO)(PPh(3))(NH(2)Ph)][OTf] (4).

Journal Article↗
PubMed2002

Kinetics and mechanism of ligand interchange in pentacyano-L-osmate(II) complexes (L = H(2)O, NH(3), N-heterocyclic ligands).

The new complex, K(3)[Os(CN)(5)NH(3)].2H(2)O, a convenient precursor for the pentacyano-L-osmate(II) series, was prepared and characterized by chemical analysis, cyclic voltammetry, and IR and UV-vis spectroscopies. By controlled aquation in weakly acidic medium, the [Os(CN)(5)H(2)O](3-) ion was generated. Weak absorptions in the UV region for L = H(2)O, NH(3), and CN(-) were found at 287, 272, and 240 nm, respectively, and were assigned to d-d transitions, in terms of a model for tetragonally distorted ions also valid for the members of the iron and ruthenium series. The kinetics of the formation and dissociation reactions of the [Os(CN)(5)L](n-) ions, L = pyridine (py), pyrazine (pz), N-methylpyrazinium (mpz(+)), etc., were studied. At 25.0 degrees C, the formation rate constants for the neutral ligands pz and isonicotinamide were ca. 0.13 M(-1) s(-1) and slightly increased for L = mpz(+) and decreased for isonicotinate. The enthalpies of activation were ca. 22.0 kcal mol(-1), independently of the entering L, and the activation entropies were all positive, ca. 11-13 cal K(-1) mol(-1). The dissociation reactions showed a saturation rate behavior of k(obs) (s(-1)) as a function of the concentration of the scavenger ligand. The specific dissociation rate constant at 25.0 degrees C was 1.06 x 10(-7) s(-1) for L = NH(3) and around 10(-9) s(-1) for py, pz, and mpz(+) (extrapolated to 25.0 degrees C from values measured in the range 60-95 degrees C). These small values are associated with high activation enthalpies (range 30-35 kcal mol(-1)) and positive activation entropies (range 10-20 cal K(-1) mol(-1)). The evidence for both the formation and dissociation processes shows that dissociative mechanisms are operative, as for the iron and ruthenium analogues.

Journal Article↗
PubMed2003

4,4'-dithiodipyridine as a bridging ligand in osmium and ruthenium complexes: the electron conductor ability of the -S-S- bridge.

The compounds [Ru(NH(3))(5)(dtdp)](TFMS)(3), [Os(NH(3))(5)(dtdp)](TFMS)(3), [(NH(3))(5)Os(dtdp)Os(NH(3))(5)](TFMS)(6), [(NH(3))(5)Os(dtdp)Ru(NH(3))(5)](TFMS)(3)(PF(6))(2), and [(NH(3))(5)Os(dtdp)Fe(CN)(5)] (dtdp = 4,4'-dithiodipyridine, TFMS = trifluoromethanesulfonate) have been synthesized and characterized by elemental analysis, cyclic voltammetry, electronic, vibrational, EPR, and (1)H NMR spectroscopies. Changes in the electronic and voltammetric spectra of the ion complex [Os(NH(3))(5)(dtdp)](3+) as a function of the solution pH enable us to calculate the pK(a) for the [Os(NH(3))(5)(dtdpH)](4+) and [Os(NH(3))(5)(dtdpH)](3+) acids as 3.5 and 5.5, respectively. The comparison of the above pK(a) data with that for the free ligand (pK(1) = 4.8) provides evidence for the -S-S- bridge efficiency as an electron conductor between the two pyridine rings. The symmetric complex, [(NH(3))(5)Os(dtdp)Os(NH(3))(5)](6+), is found to exist in two geometric forms, and the most abundant form (most probably trans) has a strong conductivity through the -S-S- bridge, as is shown by EPR, which finds it to have an S = 1 spin state with a spin-spin interaction parameter of 150-200 G both in the solid sate and in frozen solution. Further the NMR of the same complex shows a large displacement of unpaired spin into the pi orbitals of the dttp ligand relative to that found in [Os(NH(3))(5)(dtdp)](3+). The comproportionation constant, K(c) = 2.0 x 10(5), for the equilibrium equation [Os(II)Os(II)] + [Os(III)Os(III)] right harpoon over left harpoon 2[Os(II)Os(III)] and the near-infrared band energy for the mixed-valence species (MMCT), [(NH(3))(5)Os(dtdp)Os(NH(3))(5)](5+) (lambda(MMCT) = 1665 nm, epsilon = 3.5 x 10(3) M(-)(1) cm(-)(1), deltanu(1/2) = 3.7 x 10(3) cm(-)(1), alpha = 0.13, and H(AB) = 7.8 x 10(2) cm(-)(1)), are quite indicative of strong electron delocalization between the two osmium centers. The electrochemical and spectroscopic data for the unsymmetrical binuclear complexes [(NH(3))(5)Os(III)(dtdp)Ru(II)(NH(3))(5)](5+) (lambda(MMCT) = 965 nm, epsilon = 2.2 x 10(2) M(-)(1) cm(-)(1), deltanu(1/2) = 3.0 x 10(3) cm(-)(1), and H(AB) = 2.2 x 10(2) cm(-)(1)) and [(NH(3))(5)Os(III)(dtdp)Fe(II)(CN)(5)] (lambda(MMCT) = 790 nm, epsilon = 7.5 x 10 M(-)(1) cm(-)(1), deltanu(1/2) = 5.4 x 10(3) cm(-)(1), and H(AB) = 2.0 x 10(2) cm(-)(1)) also suggest a considerable electron delocalization through the S-S bridge. As indicated by a comparison of K(c) and energy of the MMCT process in the iron, ruthenium, and osmium complexes, the electron delocalization between the two metal centers increases in the following order: Fe < Ru < Os.

Journal Article↗
PubMed2004

Alkaline side-coordination strategy for the design of nickel(II) and nickel(III) bis(1,2-diselenolene) complex based materials.

The deprotonated form of the pyrazine-2,3-diselenol (pds) ligand, pds(2-), reacts with Ni(II) inorganic salts to form the nickel compounds [Ni(II)(pds)(2)](nBu(4)N)(2) (1), [Ni(II)(pds)(2)]Na(2).2H(2)O (2), and [Ni(III)(pds)(2)](2)Na(2).4H(2)O (3), depending on the reaction conditions. They are characterized by NMR, EPR, UV-vis, and IR spectroscopies, elemental analysis, cyclic voltammetry, and X-ray crystallography. The crystal structure of compound 3 shows the formation of segregated stacks of Ni(pds)(2-) units, with a strong dimerization along the stacks. The stacked fashion of the crystal packing was expected since the supramolecular forces of the alkaline side coordination to the pyrazine moieties dominate, as happens in the recently reported analogous copper system [Cu(III)(pds)(2)]Na.2H(2)O. The structure of 2 further emphasizes the alkaline coordination as the dominating supramolecular event, and an orthogonal array of 2D layers is observed. The absence of alkaline cations in complex 1 is reflected in a crystal packing with isolated complex Ni(pds)(2)(2-) units. The dimerization found in the paramagnetic Ni(III) complex 3 promotes a very strong antiferromagnetic interaction, leading to a singlet ground state.

Journal Article↗
PubMed2006

Synthesis, characterization, and reactivity of [Ru(bpy)(CH3CN)3(NO2)]PF6, a synthon for [Ru(bpy)(L3)NO2] complexes.

We report a high yield, two-step synthesis of fac-[Ru(bpy)(CH3CN)3NO2]PF6 from the known complex [(p-cym)Ru(bpy)Cl]PF6 (p-cym = eta(6)-p-cymene). [(p-cym)Ru(bpy)NO2]PF6 is prepared by reacting [(p-cymene)Ru(bpy)Cl]PF6 with AgNO3/KNO2 or AgNO2. The 15NO2 analogue is prepared using K15NO2. Displacement of p-cymene from [(p-cym)Ru(bpy)NO2]PF6 by acetonitrile gives [Ru(bpy)(CH3CN)3NO2]PF6. The new complexes [(p-cym)Ru(bpy)NO2]PF6 and fac-[Ru(bpy)(CH3CN)3NO2]PF6 have been fully characterized by 1H and 15N NMR, IR, elemental analysis, and single-crystal structure determination. Reaction of [Ru(bpy)(CH3CN)3NO2]PF6 with the appropriate ligands gives the new complexes [Ru(bpy)(Tp)NO2] (Tp = HB(pz)3-, pz = 1-pyrazolyl), [Ru(bpy)(Tpm)NO2]PF6 (Tpm = HC(pz)3), and the previously prepared [Ru(bpy)(trpy)NO2]PF6 (trpy = 2,2',6',2' '-terpyridine). Reaction of the nitro complexes with HPF6 gives the new nitrosyl complexes [Ru(bpy)TpNO][PF6]2 and [Ru(bpy)(Tpm)NO][PF6]3. All complexes were prepared with 15N-labeled nitro or nitrosyl groups. The nitro and nitrosyl complexes were characterized by 1H and 15N NMR and IR spectroscopy, elemental analysis, cyclic voltammetry, and single-crystal structure determination for [Ru(bpy)TpNO][PF6]2. For the nitro complexes, a linear correlation is observed between the nitro 15N NMR chemical shift and 1/nu(asym), where nu(asym) is the asymmetric stretching frequency of the nitro group.

Journal Article↗
PubMed2004

Redox-active star molecules incorporating the 4-benzoylpyridinium cation: implications for the charge transfer efficiency along branches vs across the perimeter in dendrimers.

We report the redox properties of four star systems incorporating the 4-benzoyl-N-alkylpyridinium cation; the redox potential varies along the branches but remains constant at fixed radii. Bulk electrolysis shows that at a semi-infinite time scale all redox centers are electrochemically accessible. However, voltammetric analysis (cyclic voltammetry and differential pulse voltammetry) shows that only two of the three redox-active centers in the perimeter are electrochemically accessible during potential sweeps as slow as 20 mV s-1 and as fast as 10 V s-1. On the contrary, both redox centers along branches are accessible electrochemically within the same time frame. These results are explained in terms of slow through-space charge transfer and the globular 3-D folding of the molecules and are discussed in terms of their implications on the design of efficient redox functional dendrimers.

Journal Article↗
PubMed1996

Determination of UV stabilizers in PET bottles by high performance-size exclusion chromatography.

A Size Exclusion Chromatography-High Performance Liquid Chromatography (SECHPLC) method to determine antioxidants and UV stabilizers in PET bottles has been developed. In only a single run a synthetic mixture of the stabilizers was separated and quantified. The detection limit obtained for BHT, Tinuvin 326, Cyasorb UV 5411, and Tinuvin P was about 0.1 microgram/g and for Irgafos 168 it was 1.0 microgram. RSD values were lower than 3%. Tinuvin P was identified and quantified in PET bottle extracts. Olive oil, soybean oil and sunflower oil showed well defined separation from Tinuvin P at the same conditions of analysis. Cyclic dimers were identified in the PET extracts.

Animals↗
PubMed2000

A long-term study on seasonal changes of gametic disequilibrium between allozymes and inversions in Drosophila subobscura.

Seasonal variation (spring, early summer, late summer, and autumn) of gametic disequilibrium between gene arrangements (OST and O3+4) of the O chromosome and Lap, Pept-1, and Acph allozyme loci, located inside these inversions, has been recorded in a natural population of Drosophila subobscura during seven years over a 15-year period. The length of the study allowed us to investigate the temporal variation of the allozyme-inversion associations by statistical methods of time series analysis. Cyclic seasonal changes of allozyme-inversion associations for both Lap and Pept-1 are detected in the natural population. In both cases, the patterns of seasonal change are due to the seasonal change of frequency of Lap and Pept-1 allozymes occurring exclusively within the OST gene arrangement. In contrast, the allozyme frequencies at these loci within the O3+4 gene arrangement are stable along seasons. The patterns of temporal variation of allozyme-inversion associations for Lap and Pept-1 in the natural population are contrasted with those previously published that correspond to gene arrangements of the O chromosome and nucleotide polymorphism at the rp49 region located inside these inversions, suggesting that natural selection is operating on these allozyme-inversion associations.

Acid Phosphatase↗