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Studies the structure and electronic state of photoexcited fullerene linked with a nitroxide radical based on an analysis of a two-dimensional electron paramagnetic resonance nutation spectrum. Effective Hamiltonian and resonance field; Dipolar interaction between radical and triplet carbon.

Two-dimensional (2D) Fourier-transform (FT) electron paramagnetic resonance (EPR) nutation experiments were done in order to verify anomalous flip-angle dependence of a FT–EPR spectrum of a photochemically generated spin-correlated radical pair (SCRP). It was demonstrated by both the experiment and theory that the signals of SCRP have additionally higher and lower nutation frequencies than that of a free radical. This spectroscopy provides a direct spectroscopic evidence of spin-correlation within SCRP, and enables one to partially separate SCRP signals from free radical signals in the 2D EPR spectrum. © 1995 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Background: Pigs with defined swine leukocyte antigen (SLA) haplotypes and their detailed information are useful for transplantation and immunological studies. We developed two herds of SLA homozygous Duroc pigs with novel SLA haplotypes and characterized their reproductive potential. Methods: For selective inbreeding, a pair of Duroc pigs was chosen as initial breeders, and substantial breeding within progenies was carried out for eight generations. In the selective breeding Duroc pigs, SLA haplotypes were assigned by nucleotide sequence determination of reverse transcription polymerase chain reaction (RT-PCR) products of three SLA classical class I genes and two class II genes. Based on this sequence information, we developed a rapid and simple SLA class II DNA typing method by polymerase chain reaction-sequence specific primer (PCR-SSP) technique. As a complementary method for the characterization of the SLA haplotypes, genetic polymorphisms of 36 microsatellite (MS) markers within the SLA region were also analyzed in the selective breeding pigs with SLA homozygous/heterozygous haplotypes. Results: Among the selective breeding pigs from the third to fifth generations, only two SLA haplotypes were identified by the RT-PCR based SLA typing method; Hp-27.30 ( SLA-1* 08an03, SLA-1*06an04, SLA-2* 0102, SLA-3* 0101 DRB1* 1101 and DQB1*0503) and Hp-60.13 ( SLA-1*an02, SLA-2* 1002, SLA-3* 0502, DRB1*0403 and DQB1*0303). In these two SLA haplotypes, two class I haplotypes, Hp-27.0 and Hp-60.0, are novel. Furthermore, two class II haplotypes, Hp-0.30 and Hp-0.13, which were previously reported in Korean native pigs and pigs of Hanford breed, respectively, were also assigned by a simple assay using a PCR-SSP technique in the entire selective breeding stock. Moreover, two haplotype specific MS patterns were observed across the entire SLA region in the selective breeding (homozygous/heterozygous) pigs. No morphological abnormalities were observed in selective breeding pigs. The theoretical inbreeding coefficient at the eighth generation was 78.5%. In all generations of selective breeding pigs, litter sizes were comparable and weaning weights from the fifth to eighth generation produced progenies significantly lighter (P < 0.01) than those in the non-selective breeding pigs. Conclusions: We established and characterized SLA homozygous Duroc herds with two kinds of haplotypes that can be used as a new resource for transplantation and other biomedical studies. [ABSTRACT FROM AUTHOR]

Abstract: We present a new technique for a microwave pulse modulator that generates a short microwave pulse of approximately 1ns for use in an electron paramagnetic resonance (EPR) spectrometer. A quadruple-frequency multiplier that generates a signal of 16–20GHz from an input of 4–5GHz was employed to reduce the rise and fall times of the pulse prepared by a PIN diode switch. We examined the transient response characteristics of a commercial frequency multiplier and found that the device can function as a multiplier for pulsed signal even though it was designed for continuous wave operation. We applied the technique to a Ku band pulsed EPR spectrometer and successfully observed a spin echo signal with a broad excitation bandwidth of approximately 1.6mT using 80° pulses of 1.5ns. [Copyright &y& Elsevier]

Focuses on the photodissociation of Bis(S-benzyl-1,2-diphenyl-1,2-ethylenedithioalto) metal (Ni, Pd, Pt) complexes. Preparation of complexes; Simultaneous observations of UV-Vis absorption and EPR spectra; First and second steps of the photodissociation; Spin density on the central metal.

The lowest excited triplet (T1) ππ*states of gallium (Ga) and various rhodium (Rh) 5,10,15-trispentafluorophenylcorroles (Cors) were studied in the liquid crystal (LC) E-7 and inrigid glasses by time-resolved electron paramagnetic resonance (TR-EPR)spectroscopy. The triplet sublevel energies were experimentally determinedby the alignment of the molecules in the LC and by magnetophotoselectionin the glass. The sublevel scheme of GaCor was determined by calculatingthe zero field splitting (ZFS) parameters. Axial ligand effects andquantum chemical calculations were used for the sublevel assignmentof RhCors. The anisotropic EPR parameters were used to determine theimportant higher excited states and the magnitudes of their spin–orbitcoupling (SOC) contributions were evaluated. On the basis of theseresults and analyses, the EPR parameters and triplet lifetime werediscussed for each RhCor complex. [ABSTRACT FROM AUTHOR]

Abstract: The lowest excited triplet state of free-base 5,10,15-trispentafluorophenylcorrole (H3Cor) was studied in rigid glass by time-resolved electron paramagnetic resonance (TR-EPR) spectroscopy. Triplet sublevels were experimentally determined by using magnetophotoselection and liquid crystal. Quantum chemical calculations of zero-field splitting parameters D and E were used for the sublevel assignment. The out-of-plane sublevel T z was found to be the lowest; namely, D is positive for H3Cor, in contrast to previous reports. The origin of the difference is discussed in detail. Preliminary TR-EPR experiments on rhodium corrole, accompanied by the quantum chemical calculations, emphasize the important contribution of spin-orbit couplings. [Copyright &y& Elsevier]

A pulse control and data acquisition system with high time resolution of 300 ps and data-averaging rate of 100 kHz for a pulsed-ESR spectrometer was constructed. The system consists of two sets of 3.34 GHz data timing generator and a dual-channel analog-to-digital converter with 1 GHz samples, both of which are commercially available. We developed a scheme and software to control these equipments with high efficiency in pulsing design, data acquisition, and accurate synchronization of the devices. The system was developed at Ku band (17.5 GHz) and demonstrated some examples of electron spin echo and double quantum measurements. [ABSTRACT FROM AUTHOR]

Objective--To investigate effects of short- and long-term administration of glucocorticoids, feeding status, and serum concentrations of insulin and cortisol on plasma leptin concentrations in dogs. Animals--20 nonobese dogs Procedure--For experiment 1, plasma leptin concentrations and serum concentrations of insulin and cortisol were monitored for 24 hours in 4 dogs administered dexamethasone (0.1 mg/kg, IV) or saline (0.9% NaCl) solution for fed and nonfed conditions. For experiment 2, 11 dogs were administered prednisolone (1 mg/kg, PO, q 24 h for 56 days [7 dogs] and 2 mg/kg, PC, q 24 h for 28 days [4 dogs]) and 5 dogs served as control dogs. Plasma leptin and serum insulin concentrations were monitored weekly. Results--For experiment 1, dexamethasone injection with the fed condition drastically increased plasma leptin concentrations. Furthermore, injection of saline solution with the fed condition increased plasma leptin concentrations. These increases in plasma leptin concentrations correlated with increases in serum insulin concentrations. Dexamethasone injection with the nonfed condition increased plasma leptin concentrations slightly but continuously. Injection of saline solution with the nonfed condition did not alter plasma leptin concentrations. For experiment 2, prednisolone administration at either dosage and duration did not alter plasma leptin concentrations in any dogs. Conclusions and Clinical Relevance--Dexamethasone injection and feeding increased plasma leptin concentrations in dogs. In addition, dexamethasone administration enhanced the effect of feeding on increases in plasma leptin concentrations. Daily oral administration of prednisolone (1 or 2 mg/kg) did not affect plasma leptin concentrations in dogs. [ABSTRACT FROM AUTHOR]

Abstract: Some of 1,6-(N-substituted) aza-[60] fulleroids (1) and their corresponding photochemical reaction products, 1,2-(N-substituted) aziridino-[60] fullerenes (2) showed peculiar transient absorption peaks depending on the N-substituents. Although these bands are considered to concern with very slow photochemical rearrangements 1 → 2 in the excited triplet state, no definitive evidence has been obtained yet. We report on the character of the excited triplet states in these compounds by means of a time-resolved electron paramagnetic resonance technique. Definitive evidence on the involvement of intra-molecular charge transfer states is shown in this Letter. [Copyright &y& Elsevier]

Time-resolved EPR spectra were observed by means of the transient EPR technique for two kinds of fullerene dimers C120 and C120O in the lowest excited triplet (T1) states and compared with those of mono-adducts of fullerene (C60). It was found that zero-field splitting (zfs) parameters of both dimers are nearly the same as those of the monomers, indicating that the excitation is almost completely localized at one of the two fullerene units in the T1 state. [Copyright &y& Elsevier]

New mono- and bis[4-(3-hydroxy-2-methyl-4-quinolinoyloxy)-2,2,6,6-tetramethylpiperidin-1-oxyl](meso-tetraphenylporphyrinato)yttrium(III) complexes have been synthesized, and the properties of the excited states generated by photoexcitation of porphyrin were studied by time-resolved (TR) and pulsed two-dimensional electron paramagnetic resonance (EPR) spectroscopy. A TR-EPR spectrum was observed in the quartet (S = 3/2) or quintet (S = 2) states generated from interactions of one or two radicals with the photoexcited triplet state of the porphyrin. The zero-field splitting D values of these states were analyzed in terms of those of the triplet and the radical-triplet pair. The spin states of the excited states were definitely assigned by measuring the nutation frequencies with pulsed EPR. [ABSTRACT FROM AUTHOR]

Anti-insulin immunoglobulin G (IgG) has been found in the sera of healthy cats. To determine the concentrations of these antibodies, an enzyme-linked immunosorbent assay (ELISA) for anti-insulin IgG was developed. ELISA maintained the linearity of a standard concentration line between 67.5 and 2160 ng/ml. The coefficients of variances (CVs) of intra-assays in two different plasma samples were 4.0% and 3.7%, respectively. The inter-assay CVs in two different plasma samples were 5.1% and 6.9%, respectively. The dilution curves of two samples were rectilinear. Anti-insulin IgG was detected in all 84 of the healthy cats that were tested. Plasma anti-insulin IgG concentrations ranged from 80 to 1578 μg/ml, with a median concentration of 221 μg/ml, and this value correlated positively with total plasma IgG concentrations (r = 0.383, p < 0.01). In an intravenous glucose tolerance test, plasma antiinsulin IgG concentrations did not alter, even with changes in plasma glucose and insulin concentrations. The ELISA that was developed was able to determine plasma anti-insulin IgG in domestic cats, and confirmed that all healthy cats had plasma anti-insulin IgG. Determining the plasma concentrations of antiinsulin IgG in cats with various pathological conditions might clarify the role of anti-insulin IgG. [ABSTRACT FROM AUTHOR]

Abstract: In alkaline aqueous solutions, 3,4-diaminobenzoate (H2(2LPDA)−) reacts with PtII to form a 1:2 (Pt:L) complex that intensely absorbs near-infrared (NIR) light at 713nm (ε =8.0×104 M−1 cm−1). The absorption disappeared at pH<3 (in DMSO), showing pH-responsive switching of the NIR absorption. By comparing the NIR-absorbing behavior of this complex to that of a complex, [PtII(1LISQ)2]2−, containing the analogous phenylenediamine ligand [(1LISQ)2− = o-diiminobenzosemiquinonate radical], the complex can be formulated as [PtII(2LISQ)2]2−. The assignment of the entity was consistent with the redox and spectroelectrochemical behaviors and electronic spin resonance (ESR) spectroscopy. First, one-electron oxidation of [PtII(2LISQ)2]2− formed an ESR-silent complex assignable to the dimeric complex [{PtII(2LISQ)(2LIBQ)}2]2− [(2LIBQ)= o-iminobenzoquinone form] in which the two radical centers at were antiferromagnetically coupled. Second, the one-electron reduced complex of [PtII(2LISQ)2]2− exhibited an ESR signal attributed to [PtII(2LISQ)(2LPDA)]3− ; 34% of the electronic spin was located at the PtII center rather than on the moiety. The pH-responsive switching-off of the NIR absorption was thus rationally explained by oxidation of [PtII(2LISQ)2]2− to [{PtII(2LISQ)(2LIBQ)}2]2− by the increase of the rest potential of the solution in the lower pH region. [Copyright &y& Elsevier]

The oxidation of a redox-active tyrosine residue YZ in photosystem II (PSII) is coupled with proton transfer to a hydrogen-bonded D1-His190 residue. Because of the apparent proximity of YZ to the water-oxidizing complex and its redox activity, it is believed that YZ plays a significant role in water oxidation in PSII. We investigated the g-anisotropy of the tyrosine radical YZ∙ to provide insight into the mechanism of YZ∙ proton-coupled electron transfer in Mn-depleted PSII. The anisotropy was highly resolved by electron paramagnetic resonance spectroscopy at the W-band (94.9 GHz) using PSII single crystals. The gX-component along the phenolic C-O bond of YZ∙ was calculated by density functional theory (DFT). It was concluded from the highly resolved g-anisotropy that YZ loses a phenol proton to D1-His190 upon tyrosine oxidation, and D1-His190 redonates the same proton back to YZ∙ upon reduction. [ABSTRACT FROM AUTHOR]

Abstract: Peroxisome proliferator-activated receptors (PPARs) are ligand-activated transcription factors implicated in lipid metabolism. In this study, the full-length cDNA of canine PPARβ and γ were sequenced, and expression of PPARs was evaluated in normal tissues and primary cultures of adipocytes in dogs, followed by investigations for polymorphisms of canine PPARγ. Comparison of the deduced amino acid sequences of canine PPARβ and γ cDNA with that of human PPARβ and γ cDNA revealed 95.9% and 98.2% identity, respectively. PPARβ expression was ubiquitous and high PPARγ expression was detected in the subcutaneous and omental adipose tissues, spleen and large intestine. Canine PPARγ mRNA expression in cultured adipocytes began to increase from 4 days after induction of differentiation, and increased nearly ninefold within 10 days after induction of differentiation. Although expression level of PPARα was low in the cultured adipocytes, it slightly increased within 10 days. In contrast, expression of PPARβ showed only small variations during adipocyte differentiation, though expression levels were relatively high. These results suggest that PPARγ may play an important role in adipocyte differentiation in dogs. Investigations for polymorphisms of PPARγ revealed a silent polymorphism, C1362T, in 3 of 92 dogs. [Copyright &y& Elsevier]

The newly synthesized tetra(quinoline—TEMPO)yttrium(III) potassium salt shows interesting structural features at the molecular and supramolecular levels, revealed by the analysis of the X-ray diffraction data. The magnetic susceptibility and EPR data corroborated with structural considerations showed that the exchange and dipolar spin coupling interactions are taking place at the nodes assembling the supramolecular 2D structure. The Y(III) center shows antiprismatic octacoordination, close to the idealized D2 symmetry. The diamagnetic transition metal plays no role in mediating the radical interactions since the TEMPO-type fragments are remote from the chelating moieties of the ligand. In turn, significant interaction occurs on the nodes consisting in the quasi-rectangular coordination of potassium counterions by the spin-bearing TEMPO groups coming from four distinct complex units. The antiferromagnetic susceptibility was consistently modeled by a spin Hamiltonian based on the rectangle topology of four spins S = ½. The fitted exchange parameters are Ja = -5.1 cm-1 and Jb = -3.4 cm-1 for the edges, imposing Jd = 0 for the diagonal. These values are in excellent agreement with the ab initio results Ja = -4.83 cm-1, J0 = -3.44 cm-1, Jd = -0.07 cm-1 obtained in a CASSCF(12,8) calculation. Based on the reliability of the ab initio results we were able to select the presented J parameters among several versions of multiple solutions with acceptable goodness of the fit. A methodological caveat about the artifacts of the automatic use of best fit parameters, in the absence of supplementary criteria, in the context of relative blindness of magnetic susceptibility modeling, is raised. The details of the EPR spectrum at 10 K are also consistent, in the frame of dipolar approximation, with the model of four interacting spins at the nodes of the supramolecular assembling. [ABSTRACT FROM AUTHOR]

Objective--To evaluate postprandial changes in the leptin concentration of CSF in dogs during development of obesity. Animals--male Beagles. Procedures--Weight gain was induced and assessments were made when the dogs were in thin, optimal, and obese body conditions (BCs). The fat area at the level of the L3 vertebra was measured via computed tomography to assess the degree of obesity. Dogs were evaluated in fed and unfed states. Dogs in the fed state received food at 9 AM. Blood and CSF samples were collected at 8 AM, 4 PM, and 10 PM. Results--Baseline CSF leptin concentrations in the thin, optimal, and obese dogs were 24.3 ± 2.7 pg/mL, 86.1 ± 14.7 pg/mL, and 116.2 ± 47.3 pg/mL, respectively. In the thin BC, CSF leptin concentration transiently increased at 4 PM. In the optimal BC, baseline CSF leptin concentration was maintained until 10 PM. In the obese BC, CSF leptin concentration increased from baseline value at 4 PM and 10 PM. Correlation between CSF leptin concentration and fat area was good at all time points. There was a significant negative correlation between the CSF leptin concentration- to-serum leptin concentration ratio and fat area at 4 PM; this correlation was not significant at 8 AM and 10 PM. Conclusions and Clinical Relevance--Decreased transport of leptin at the blood-brain barrier may be 1 mechanism of leptin resistance in dogs. However, leptin resistance at the blood-brain barrier may not be important in development of obesity in dogs. [ABSTRACT FROM AUTHOR]

Bis-(quinoline-TEMPO)-yttrium-tetraphenylporphyrin complexes having potassium and silver counter cations have been studied by cw-EPR in their ground states and by time-resolved (TR) EPR and two-dimensional (2D) nutation spectroscopy in the excited states after laser excitation. Simulations of the TR-EPR spectra at 30&ThickSpace;K and at room temperature were made, yielding zero-field splitting parameters D and E, and g values. The parameters obtained together with the nutation frequencies clearly assigned the excited states of the bis-radical complexes having counter cations of potassium and silver as quartet and quintet states, respectively. This result is explained by modulation of radical–triplet interactions by the counter ion due to different sizes of metal ions. [ABSTRACT FROM AUTHOR]