Study on reproductive endocrinology of human placenta (II)--Hormone secreting activity of cytotrophoblast cells.

The capability of cytotrophoblast cells to produce hCG, progesterone, estrogen, cGnRH and beta-endorphin in vitro has been demonstrated in serum-free culture medium. Before experiment, a 24-h preculture was carried out in order to remove the endogenous hormones of the tissue. During a period of 8 days' culture, the cytotrophoblast cells could constantly produce a small amount of hCG. The production of progesterone rose rapidly and became doubled within six days. The estrogen secretion showed a similar pattern in the presence of androstenedione, a precursor of estrogen, indicating the elevation of aromatase activity in the cells. The elevation of the enzyme activity has been further demonstrated not to be induced by androstenedione. In both cytotrophoblast and syncytiotrophoblast cell cultures, cGnRH was only detected in the culture of cytotrophoblast cells, with a value up to 4 pg/10(5) cells/24 h. However, beta-endorphin was identified both in cytotrophoblast and syncytiotrophoblast cells. Its content increased significantly in the medium of cytotrophoblast cell culture from the 4th to 6th days, but declined in the medium of syncytiotrophoblast cell culture. The results demonstrate clearly that the cytotrophoblast cells are the sole origin of GnRH in human placenta and are also able to synthesize beta-endorphin and steroid hormones. The findings indicate that there is no such a sharp functional demarcation existing between these two kinds of trophoblast cells as suggested before. The data are of significance for a better understanding of the mechanism of hormonal regulation in placenta.     

Study on reproductive endocrinology of human placenta--culture of highly purified cytotrophoblast cell in serum-free hormone supplemented medium.

A new method of long-term culture of cytotrophoblast cells in serum-free medium has been developed. Cytotrophoblast cells were isolated with cold trypsin and purified by unit gravity sedimentation through BSA density gradients. The cells were cultured in the FD medium with supplement of EGF, insulin, transferrin and sodium selenite. They could survive over three weeks. The results showed that both EGF and insulin stimulated hCG and progesterone secretion and that sodium selenite elevated hCG output but not progesterone secretion. Transferrin produced synergistic effect with EGF and insulin on hCG and progesterone secretion but it was ineffective when used alone. This study demonstrates that the four growth factors mentioned above are essential for the survival of cytotrophoblast cells in vitro. It is therefore suggested that EGF, insulin and selenium may possibly be involved in the regulation of hCG and progesterone secretion in the human placenta.     

Cu(II), Fe(III)与人血清白蛋白相互作用的荧光光谱研究

通过研究Cu(II),Fe(III)对人血清白蛋白(HSA)内源荧光的猝灭,探讨了Cu(II),Fe(III)与人血清白蛋白的结合机理。基于Forster非辐射能量转移机理。获得了人血清白蛋白第一类Cu(II)结合部位与214位色氨酸残基间的距离为1.8nm,并讨论了Cu(II),Fe(III)与HSA结合的差异。     

The effect of molybdenum(VI) on the production of arsine by the tetrahydroborate(III) reaction

Molybdenum(VI) increases signals in the determination of arsenic after reduction by tetrahydroborate(III). An increase in the signal by up to two-and-a-half fold is observed when arsenic(III) is determined in the presence of sulphuric and hydrochloric acid concentrations of 0.01-0.02M. The enhancement effect disappears at higher acid concentrations and is eliminated by the presence of L-cysteine. Signals from other hydride-forming elements (antimony, bismuth and tin) were reduced in the presence of molybdenum(VI). Reduction of interferences in the hydride-forming reaction from nickel and cobalt is observed, so that the range of tolerance of these elements is extended by one and two orders of magnitude, respectively. The interference reducing effect is not as profound as that observed with L-cysteine.     

Alkaloid production by callous tissue cultures of Cereus peruvianus (Cactaceae)

The morphologically undifferentiated cells of nonregenerant callous tissue of Cereus peruvianus cultured in the original medium and in medium supplemented with tyrosine were used as an alkaloid source. Comparison of alkaloid production by C. peruvianus plants and by callous tissues indicated that alkaloid levels were almost twice as high in callous tissues as in shoots of C. peruvianus plants. The ratio of alkaloid concentration between mature plant and morphologically und ifferentiated cells of callous tissue was 1∶1.7. A relationship between culture medium containing tyrosine and alkaloid production was also observed in the callous tissues of C. peruvianus. Since increased alkaloid production may be induced by additional factors such as tyrosine, increasing levels of tyrosine or other conditions of the culture medium may be considered factors for inducing higher alkaloid production by C. peruvianus callous tissues.     

Oxidation of chromium(III) by alkaline hexacyanoferrate(III)

Alkaline hexacyanoferrate(III) oxidation of freshly prepared solutions of Cr^III (pH>12) at 27°C follows the rate law, Equation 1:

Catechol releases iron(III) from ferritin by direct chelation without iron(II) production

It has been traditionally considered that catechols release iron from ferritin by reduction to iron(II), which diffuses through the ferritin channels into the intracellular milieu where it participates in the Fenton reaction, producing highly toxic hydroxyl radicals. However, in the present work we have proved that the mechanism of the release of iron from ferritin by catechol does not take place by iron(II) reduction but by direct iron(III) chelation and therefore without iron(II) production. A possible extension of these findings to other catechols is discussed on the basis of the stability with respect to the internal redox reaction of the iron(III)-catechol complexes.     

Synthesis and Study of Aluminum Hexamolybdenocobaltate(III) and Hexamolybdenochromate(III)

Aluminum hexamolybdenocobaltate and hexamolybdenochromate of the Al[MMo₆O₁₈(OH)₆] · 16H₂O composition, where M = Co(III) or Cr(III), were synthesized for the first time. X-ray diffraction study shows that the crystals of the compounds are triclinic; space group P1, Z = 1, and _calcd = 2.665 and 2.611 g/cm³, respectively. The compounds were studied by IR spectroscopy and thermogravimetry.     

Thermal studies on oxalate complexes. II. Complexes of iron (III) and chromium (III)

The decomposition of solid K₃[Fe(C₂O₄)₃] · 2 H₂O and K₃[Cr(C₂O₄)₃] · 3 H₂O has been studied using TGA and DSC. After dehydration, the chromium compound was found to decompose by the loss of CO in two steps, the loss of CO₂ and additional CO, and finally the loss of CO₂. The final product appears to be either K₃CrO₃ or the mixed oxides of chromium and potassium. Kinetic parameters and enthalpy data are presented for these reactions. In the case of K₃[Fe(C₂O₄)₃] · 2 H₂O, dehydration is followed by the loss of CO₂ and CO, CO₂ alone, and finally CO. The final product appears to be a basic carbonate of the type K₃[FE(O)₂(CO₃)]. Kinetic and thermal data are presented for most of these decomposition reactions.     

Thermal studies on oxalate complexes. III. Complexes of cobalt(III) and cobalt(II)

The decomposition of K₂[Co(C₂O₄)₂] and K₃[Co(C₂O₄)₃] has been studied using TG. In the case of the latter compound, the first step involves the rupture of all the oxalates and one of the resultant carbonates to liberate CO₂ and three molecules of CO. Subsequent steps involve the loss of CO₂. In the case of K₂[Co(C₂O₄)₂], four decomposition reactions are observed. The first involves the loss of only CO. Subsequent steps involve loss of CO₂, CO₂ and CO, and CO₂, respectively. Basic carbonates appear to be the intermediate products. Kinetic parameters are presented for most of the reactions.     

Study on carbon-hydrogen activation of ketones by Gold(III) complexes and the synthesis and characterization of two ketonylgold(III) complexes

The acetonylgold(III) compound [Au(ppy)(CH₂COCH₃)Cl] (1) (ppy = 2-phenylpyridine) was unexpectedly obtained during the crystallization process of Au(III) lactate complex [Au(ppy)(CH₃CHOHCOO⁻)Cl]. This new structure prompted us to further study the role of Au(III) complexes on the carbon-hydrogen activation of ketones. Complex [Au(ppy)(CH₂COCH₃)NO₃] (2) was synthesized by reacting [Au(ppy)(NO₃)₂] with acetone while the ketonyl Au(III) complex [Au(apd)Cl₂] (3) (Hapd = 2-acetylpyridine) was obtained through carbon-hydrogen bond activation of the acetyl group. The crystal structures of 1 and 2 have common features: a square-planar Au(III) centre coordinated by one five-membered chelate ring, one acetonyl ligand and one anion (chloride or nitrate). Both structures show that carbon-hydrogen activation of acetone by 2-phenylpyridine-Au(III) complexes leads to the formation of acetonyl-Au(III) complexes. The Au-CH₂ bond lengths (2.067(7) Å, 1 and 2.059(5) Å, 2) are similar to each other but longer than the Au-C (phenyl) bond lengths. The two softest ligands (carbanion) are also cis to each other in the thermodynamically most stable isomer. In complex 3, the σ-bonded acetyl group is confirmed by ¹³C DEPT NMR spectroscopy.     

Recovery of Au(III) ions by Au(III)-imprinted hydrogel

A new Au(III)-imprinted hydrogel (Au(III)-Imp) was prepared by the photopolymerisation of 4-acryloylmorpholine (AcM), 2-hydroxyethyl acrylate (HEA), and poly(ethylene glycol) diacrylate (cross-linking monomer, PEG-DA) in the presence of gold ions. In addition, non-imprinted hydrogel (N-Imp) was similarly prepared without Au(III) ions The Au(III)-Imp hydrogel was characterised by several techniques. To achieve the optimal conditions, effect of pH, time, and initial metal ion concentrations were investigated using a batch system. The pre-concentration factor for Au(III) ions was found to be at least 100. The analytical parameters of the method were determined and the method was also successfully applied to computer circuit board scrap samples. The reusability of the Au(III)-Imp hydrogel was also determined.     

Spectrophotometric Study of 1, 3-Cyclohexanedione Bisthiosemicarbazone Monohydrochloride -Bi (III) Complex. Determination of Bi (III)

Abstract

The spectrophotometric study was made of red-violet 1, 3-cyclohexanedione bis-thiosemicarbazone-Bi (III) in an acidic dimethylformamide-water solution (λ_max = 540 nm, ? = 3.3 × 10^?4 1. mol^?1. cm^?1, stoichiometry 3:1, apparent stability constant (6.0 × 10¹⁰). A new method for the spectrophotometric determination of Bi (III) is proposed for concentrations between 0.7 and 7.4 ppm. The relative error (95 % confidence level) is 0.5 % for 3.7 ppm of Bi (III).

The extraction with methyl isobutyl ketone of the red-violet complex was also studied spectrophotometrically (λ_max = 550 nm, ? = 3.34 × 10⁴ 1. mol^?1.cm^?1, stoichiometry 2:1). A new method for the extraction-spectrophotometric determination of Bi (III) is proposed for concentrations, in aqueous phase, between 0.2 and 1.2 ppm. The relative error (95 % confidence level) is 0.8 % for 0.9 ppm of Bi (III).     

Studies on Cobalt(III) Metallosurfactants. Kinetics and Mechanism of Reduction of Cobalt(III) by Iron(II) in Aqueous Acid Medium

The kinetics and mechanism of reduction of the surfactant complex ions, cis-chloro/bromo(dodecylamine)(triethylenetetramine)cobalt(III) by iron(II) in aqueous solution were studied at 303, 308 and 313 K by spectrophotometry under pseudo-first-order conditions using an excess of the reductant. The second-order rate constant increases with cobalt(III) concentration and the presence of aggregation of the complex itself alters the reaction rate. The reductions are acid-independent in the range [H⁺] = 0.05–0.25 mol dm⁻³. Variation of ionic strength (μ) influences the reaction rate. Activation and thermodynamic parameters have been computed. It is suggested that the reaction of Fe²⁺(aq) with the cobalt(III) complex proceeds by an inner-sphere mechanism. The critical micelle concentration (CMC) values of these surfactant metal complexes in aqueous solution were obtained from conductance measurements. Specific conductivity data (at 303, 308 and 313 K) served for the evaluation of the temperature-dependent CMC and the standard Gibbs energy of micellization (ΔG_m⁰).     

Studies on the bacterial activity of cobalt(III) complexes. Part II. Cobalt(III) aminoacidato-complexes

Summary Cobalt(III) complexes of the typetrans-[Co(AA)₂(ox)] (where AA = aminoacidato, gly = glycinato, sar = sarcosinato, DL-ala = DL-alaninato, L-ala = L-alaninato; ox = oxalate); [Co(L-val)₂CO₃] and DL-[Co(en)₂sar]I₂ where L-val = L-valinato, en = ethylenediamine) have been investigated for their bacterial activity againstEscherichia coli B using well-cultured techniques on EMB agar and in minimal glucose media. The activities decrease in the order:trans-(N)(+)K[Co(sar)₂(ox)] >trans-(N)(+)K[Co(L-ala)₂(ox)] >trans-(N)(–)K[Co (gly)₂(ox)] >trans-(N)(+)K[Co(DL-ala)₂(ox)] >trans-(N)(+)K[Co(gly)₂(ox)] >trans(+)K[Co(DL-ala)₂(ox)] >trans-K[Co(L-val)₂CO₃].     

Dynamics of arsenic speciation in surface waters: As(III) production by algae

Algae reduce and methylate arsenate [As(V)]. The end product of the overall transformation reaction can be arsenite [As(III)] or methylated arsenic. Field and laboratory data suggest a strong correlation between the end product of the reaction and the growth rate of the algae, with As(III) only produced during log (exponential, fast) growth. The result is a peak in As(III) concentration preceding or coincident with the algal bloom. This paper analyzes data from 18 different water bodies (five lakes, one river, six estuary/marine sites, six experimental sites). Algal blooms, As(III) peaks and algal blooms with preceding or coincident As(III) peaks were identified. In total, 80 algal blooms were identified, 49 (61%) of which were associated with As(III) peaks. In 78% of water bodies algal blooms were typically (>50%) associated with As(III) peaks. The average time lag between As(III) peaks and algal blooms was 20 days (standard deviation 18 days). Copyright © 2005 John Wiley & Sons, Ltd.     

Thermodynamic Study of Iron(III) Sorption on Clay

Sorption of Fe(III) cations on Cambrian blue clay is discussed in term of the Langmuir isotherm. The thermodynamic characteristics of sorption were determined. The Gibbs energies of formation of sorbed Fe(III) aqua and hydroxo cations were calculated. The role of hydroxo complexes in sorption was considered.     

Detection of Al(III) and Ga(III) complexes with morin by electrospray ionization mass spectrometry.

The Al(III) and Ga(III) complexes formed by morin (M) in aqueous solution were investigated by means of electrospray ionization mass spectrometry (ESI-MS). In the full scan mass spectra, Al:M showed 1:2 and 2:3 stoichiometric ratios. When (S)-N-acetylserine methyl ester (Ser), as a partial mimic of the serine residue in silk, was added to Al:M and Ga:M complexes in aqueous solution, the mass spectra of Ser:Al:M showed 1:1:1 and 1:1:2 stoichiometric ratios. The patterns of the mass spectra of Ga:M and Ser:Ga:M complexes were similar to those for the corresponding Al(III) complexes. Calculated heats of formation of potential structures of the complexes, with and without bound water, were obtained using semiempirical PM3 calculations.     

Emulsion polymerization of styrene. III. Effect of Ti(III) and Cl(1) on the polymerization of styrene initiated by potassium persulfate

The emulsion polymerization of styrene initiated by potassium persulfate catalyzed by Ti⁺³ ions was studied. Two sources of Ti⁺³ ions were used: the titanium trichloride and titanium sulfate. It was found that the titanium ions used in conjunction with potassium persulfate decrease both the reaction rate and the average molecular weight. An even greater drop of reaction rate was noted when chlorine anions (TiCl₃) were present. The presence of these ions had a stabilizing effect on the polydispersity.