Fabrication of Hydrogen Boride Thin Film by Ion Exchange in MgB2.

In this study, hydrogen boride films are fabricated by ion-exchange treatment on magnesium diboride (MgB2) films under ambient temperature and pressure. We prepared oriented MgB2 films on strontium titanate (SrTiO3) substrates using pulsed laser deposition (PLD). Subsequently, these films were treated with ion exchangers in acetonitrile solution. TOF-SIMS analysis evidenced that hydrogen species were introduced into the MgB2 films by using two types of ion exchangers: proton exchange resin and formic acid. According to the HAXPES analysis, negatively charged boron species were preserved in the films after the ion-exchange treatment. In addition, the FT-IR analysis suggested that B-H bonds were formed in the MgB2 films following the ion-exchange treatment. The ion-exchange treatment using formic acid was more efficient compared to the resin treatment; with respect to the amount of hydrogen species introduced into the MgB2 films. These ion-exchanged films exhibited photoinduced hydrogen release as observed in a powder sample. Based on the present study, we expect to be able to control the morphology and hydrogen content of hydrogen boride thin films by optimising the ion-exchange treatment process, which will be useful for further studies and device applications.

Biodegradable shape memory polymers functionalized with anti-biofouling interpenetrating polymer networks.

A novel type of shape memory polyurethane (SMPU) with high mechanical properties and biodegradability was constructed using a lactone copolymer (poly(ε-caprolactone-co-γ-butyrolactone), PCLBL), a diol- or triol-based chain extender (1,5-pentanediol, glycerol and 2-amino-2-hydroxymethyl-1,3-propanediol) and a diisocyanate cross-linker (1,6-hexamethylene diisocyanate). All types of SMPUs possessed high mechanical properties, and the shape recovery test indicated that the SMPU sheets prepared using a triol-chain extender with an amine group recovered completely the original shape at 80 °C. Moreover, the degradation products of the SMPUs were innoxious, which is an important property for use in the biomedical field. Furthermore, the SMPU sheets were interpenetrated with a zwitterionic polymer, poly(carboxymethyl betaine) (PCMB), using the interpenetrating polymer network (IPN) method to additionally introduce an anti-biofouling property. Water contact angle measurements of the surface of PCMB-introduced SMPU sheets showed a drastic reduction from 87° to approximately 30° due to the exposure of the PCMB chains from the SMPU sheets. These SMPU-IPN sheets suppressed significantly both protein adsorption and cell adhesion. Consequently, the PCLBL-PU-based SMPUs interpenetrated with PCMB are promising materials for biomedical devices because of their high mechanical, shape memory, biodegradable, and anti-biofouling properties. These materials are expected to be applied to biomaterials such as embolization materials for aneurysms and a novel type of membrane for postoperative adhesion prevention.

Advantages of anchoring growth factors to materials for neural stem/progenitor cell proliferation.

Biomaterials modified with proteins such as growth and trophic factors are known to precisely regulate various cell and tissue functions. However, the mechanisms for regulation with proteins anchored to a substrate have not been extensively studied. Although we previously evaluated specific signal transduction from epidermal growth factor (EGF) anchored to a substrate to neural stem/progenitor cells (NSPCs), the internalization of immobilized-EGF and the continuity of signaling transduction were not discussed in detail. This information is important to determine the value of growth factor-anchored biomaterials in the regulation of cells. Here, we tried to clarify the mechanisms underlying immobilized-growth factor in NSPC regulation using approaches from materials science and cell biology. In this evaluation, we used EGF chimeric protein (EGF-His) and NSPCs, and found that EGF anchored to a substrate facilitated continuous signal transduction in NSPCs attached to the substrate. In addition, the anchored-EGFs were finally internalized into cells only when the proteins formed a complex with their receptors on cell membranes detached from the substrate. Finally, we concluded that continuous signal transduction by anchoring to the substrate and final internalization into cells with the detachment of anchored-proteins from a substrate are important events for efficient regulation of cell function.

Interleukin-10 chimeric protein to protect transplanted neural progenitor cells from immune responses.

The provision of adhesive scaffolding and protection from inflammatory responses are important for enhancing graft survival. We previously developed a functional hydrogel that significantly enhances the survival of cells transplanted into the midbrain striatum. Although graft survival reached approximately 40% using this hydrogel, the survival of transplanted cells required further enhancements because it ultimately produced a decrease in the number of transplanted cells. Therefore, we developed a hydrogel system that can locally prevent the inflammatory response. This hydrogel was modified by the addition of the interleukin 10 chimeric protein (IL10CP), which is selectively released from the hydrogel when triggered by an inflammatory response. This design protects transplanted cells from inflammatory response, while other host cells remain unaffected. The IL10 domains are selectively released from the hydrogel, which act locally on the immune cells to prevent the inflammatory response without the administration of an immune suppressor. The selective release of IL10 domains from the hydrogel and their activity to prevent immune responses were evaluated using various approaches. Moreover, the ability of the IL10CP-modified hydrogel to protect cells was investigated using an in vitro co-culture with activated microglia. The IL10 incorporated into the hydrogel was selectively released by the activity of matrix-metalloproteinase 9 (MMP9), and the neural progenitor cells encapsulated in the IL10CP-immobilized hydrogel were protected from activated microglia by the release of IL10s from the hydrogel by the MMP9, produced by the activated microglia. These results show that the IL10CP-modified hydrogel will be useful as a biomaterial for improving the survival of transplanted cells.

Biodegradable microparticles for strictly regulating the release of neurotrophic factors.

A lot of research has been carried out in the last decade to find a cure for neurodegenerative diseases especially Parkinson's disease but to little avail. In this study we have demonstrated the use of poly(lactic-co-glycolic acid) (PLGA)/collagen biodegradable microparticles formed using water-in-oil-in-water (W/O/W) double emulsion method, as a neurotrophic factor delivery vehicle. The microparticles were encapsulated with glial cell-derived neurotrophic factor (GDNF) fused with collagen binding peptide (CBP) immobilized to the inner collagen phase. The novelty lies in the strict regulation of release of GDNF-CBP from the microparticles as compared to a burst release from standard microparticles. The microparticles were demonstrated to be non-cytotoxic till 300 µg/2 × 105 cells and revealed a maximum release of 250 ng GDNF-CBP/mg microparticles in 0.3% collagenase. Differentiation of neural progenitor cells (NPCs) into mature neurons was demonstrated by co-culturing microparticles with cells in a medium containing collagenase which enabled the release of encapsulated GDNF-CBP, signaling the differentiation of NPCs into microtubule-associated protein 2 (MAP2)-expressing neurons. The successful ability of these microparticles to deliver neurotrophic factors and allow differentiation of NPCs into mature neurons provides some scope in its use for the treatment of Parkinson's disease and other neurodegenerative diseases.

Stimulatory action of mitemcinal (GM-611), an acid-resistant non-peptide motilin receptor agonist, on colonic motor activity and defecation: spontaneous and mitemcinal-induced giant migrating contractions during defecation in dogs.

The aim of this study was to characterize giant migrating contractions (GMCs) during spontaneous defecation in dogs and to investigate the effect of mitemcinal (an orally active and highly acid-resistant motilin receptor agonist) on colonic motility to assess the possibility of using it for the treatment of colonic motility disorders. To assess colonic motility, strain-gauge force transducers were implanted on the gastrointestinal tract of five dogs, and the behaviour of the dogs was monitored with a noctovision-video camera system. The effect of mitemcinal (0, 3, 10 or 30 mg per dog) and sennoside (300 mg per dog) on colonic motility was assessed 24 h after oral administration. During a 39-day period, the starting point of most of the 140 GMCs was between the transverse colon and the descending colon, but some variation was observed. In the daytime, the GMCs originated from somewhat more proximal positions than at night. Mitemcinal caused an increase in the GMC-index (integration of contractile amplitude and duration) and proximal translocation of the GMC starting point, but did not cause an increase in the number of defecations 12 h after administration. Sennoside, however, caused a significant increase in the number of defecations, an increase in the GMC-index, and prolongation of the duration of GMCs. The GMC starting point in the canine colon varied during spontaneous defecation. Mitemcinal was a potent prokinetic drug to mimic a spontaneous defecation compared with sennoside. Mitemcinal evacuates more intestinal luminal contents during the defecation than does sennoside.

Expression of SCC in ovarian granulosa cells and cultured cells, induced rapid structural changes in mitochondria.

In this study, the relation of P450scc expression and mitochondrial ultrastructure was examined in rat granulosa cells at the time of ovulation, and in the NIH/3T3 cells. Before ovulation in the ovary, granulosa cells of Graafian follicle which expressed only mRNA of P450scc had elongated mitochonria with lamellar cristae. After ovulation, granulosa lutein cells which expressed both P450scc mRNA and protein had oval and round mitochondria with tubular or vesicular cristae. Two different cytochrome P450scc cDNA fragments in length were subcloned into pEGFPN vector, transfected into NIH/3T3 cells, and the mitochondrial structure was examined under fluorescent microscope with GFP and by electron microscopy. 5'end of cytochrome P450scc contained mitochondrial localization signal, and was composed of about 40 amino acids. NIH/3T3 cells had filamentous and elongated mitochondria with lamellar cristae, free ribosomes, and rER. After the transfection of short fragment of SCC(scc-s:200bp), mitochondria remained filamentous and their cristae also remained lamellar. On the other hand, when almost full length of SCC fragment(scc-f:1.1kb) was transfected, globular and round mitochondria were labeled with GFP, and round or oval mitochondria with vesicular or tubular cristae could be examined by electron microscope. Our study suggests that cytochrome P450scc located in mitochondrial inner membrane plays an important role to determine the mitochondrial morphology in vivo and in vitro.

Basic studies on the equivalent cross-relaxation rate imaging (equivalent CRI)--phantom studies.

We have studied saturation transfer in hydrophilic, cross-linked copolymer gels from irradiated polymer protons to observed water protons, using f2 (ppm) profiles of [1 - (I(infinity)/I(0))], [(I(0)/I(infinity)) - 1] or 1/T(IS)(H2O), where I(0) and I(infinity) are the longitudinal magnetization of the observed water protons before and after long-time-f2-irradiation on polymer protons, respectively, and 1/T(IS)(H2O) is the cross-relaxation rate. (A) [1 - (I(infinity)/I(0))] (magnetization transfer ratio, MTR) was used in magnetic resonance imaging (MRI) as the MTR imaging. 1/T(IS)(H2O) (cross-relaxation rate) was used in the imaging of the magnetization transfer rate constant. This method was quite time-consuming compared with MTR imaging. However, f2 (ppm) profiles of [(I(0)/I(infinity)) - 1] correlated well with corresponding profiles of 1/T(IS)(H2O), because [(I(0)/I(infinity)) - 1] is equal to 1/[T(IS)(H2O)/T1(H2O)]. These results lead us to the conclusion that [(I(0)/I(infinity)) - 1] might be applicable to cross-relaxation rate (CR)-like imaging, i.e. equivalent CRI. (B) W (%) (dry weight) profiles of [(I(0)/I(infinity)) - 1] and 1/T(IS)(H2O), obtained by near-resonance f2-irradiation, seem to indicate participation of molecular rigidity and an amount of bound water. However, those values, monitored with off-resonance f2-irradiation, seem to be independent of monomer composition and to indicate mainly participation of rigidity, i.e. W (%) of copolymer gels.

Expression of beta-synuclein in normal human astrocytes.

Although alpha- and beta-synucleins are expressed predominantly in presynaptic nerve terminals, recent studies have demonstrated that alpha-synuclein is also expressed in cultured astrocytes and oligodendrocytes. We determined whether beta-synuclein might be expressed in astrocytes. Beta-synuclein mRNA and protein were detected in normal human astrocytes in culture, and immunofluorescent staining showed that beta-synuclein protein was expressed within the cytoplasm and nucleus. Furthermore, beta-synuclein immunoreactivity was present in astrocytes, but not in oligodendrocytes, in normal human brain tissues. Ultrastructurally, beta-synuclein immunoreactivity was found in the cytoplasm of astrocytes, in association with the plasma membrane, ribosomes, rough endoplasmic reticulum and the nuclear outer membrane. The novel expression of beta-synuclein in astrocytes may provide an important insight about the role of this protein.

A helical arrangement of beta-substituents of dehydropeptides: synthesis and conformational study of sequential nona- and dodecapeptides possessing (Z)-beta-(1-naphthyl)dehydroalanine residues.

Sequential nona- and dodecapeptides possessing three and four (Z)-beta -(1-naphthyl)dehydroalanine (Delta(Z)Nap) residues, Boc-(L-Ala-Delta(Z)Nap-L-Leu)(n)-OCH(3) (n = 3 and 4; Boc = t-butoxycarbonyl), were synthesized to design a rigid 3(10)-helical backbone for a regular arrangement of functional groups using dehydropeptides. Their solution conformations were investigated by NMR and CD analyses, and theoretical energy calculations. Both peptides were found to adopt a 3(10)-helical conformation in CDCl(3) from their nuclear Overhauser effect spectroscopy (NOESY) spectra, which showed intense cross peaks for N(i)H-N(i+1)H proton pairs, but no cross peaks for C(alpha)(i)H-N(i+4)H pairs. The predominance of a 3(10)-helix was also supported by solvent accessibility of NH resonances. CD spectra of both peptides in tetrahydrofuran showed strong exciton couplets at around 228 nm assignable to naphthyl side chains, which are regularly arranged along a right-handed helical backbone. Chain-length effects on conformational preference in sequential peptide -(Ala-Delta(Z)Nap-Leu)(n)- were discussed based on spectroscopic analysis, energy minimization, and molecular dynamics simulations. Consequently, the repeating number n > or = 3 forms predominantly a right-handed 3(10)-helical conformation. The energy calculation also revealed that the midpoint naphthyl groups of peptide n = 4 are highly restricted to one stable orientation. In conclusion, beta-substituted alpha,beta-dehydroalanine is expected to be a unique tool for designing a rigid molecular frame of 3(10)-helix along which beta-functional groups are regularly arranged in a specific manner.

Atp-binding cassette transporter ABC2/ABCA2 in the rat brain: a novel mammalian lysosome-associated membrane protein and a specific marker for oligodendrocytes but not for myelin sheaths.

We recently cloned a full-length cDNA of the rat ATP-binding cassette transporter 2 (ABC2, or ABCA2) protein, a member of the ABC1 (or ABCA) subfamily (-ABC1/ABCA1 is a causal gene for Tangier disease) and found it to be strongly expressed in the rat brain. In this study, we identified ABC2 as a lysosome-associated membrane protein that is being localized specifically in oligodendrocytes. The ABC2-immunolabeled cells were detected mainly in the white matter but were also scattered in gray matter throughout the whole brain. In addition, these cells were found to be colocalized with 2',3'-cyclic nucleotide-3'-phosphodiesterase (CNPase) immunoreactivity when the marker antibody for oligodendrocytes was used. However, no such colocalization was observed with markers for other kinds of glial cells. Unlike the CNP antibody, which also intensely stains myelin sheaths in the white matter, ABC2 immunoreactivity was detected only in the cell bodies of oligodendrocytes. At the ultrastructural level, ABC2 immunoreactivity was detected mostly around lysosome and partly in Golgi apparatus by electron microscopy. This was confirmed by immunocolocalization of ABC2 and lysosomal markers in a neuroblastoma cell line. Immunoblotting analysis of ABC2 from the whole brain and the ABC2-transfected cell line revealed bands at approximately 260 kDa. The result of in situ hybridization with a riboprobe for ABC2 matched the results obtained from immunostaining. These findings strongly suggest that ABC2 is a specific marker for oligodendrocytes but not for myelinsheaths and that it is as a novel mammalian lysosome-associated membrane protein involved in myelinization or other kinds of metabolism in the CNS.

Structural and conformational properties of (Z)-beta-(1-naphthyl)- dehydroalanine residue.

To understand how chemical structure of beta-substituted alpha, beta-dehydroalanine (particularly size and pi conjugation of beta substituent) affects conformational property, x-ray crystallographic analysis was performed on Boc-Ala-Delta(Z) Nap-Val-OMe [Boc: t-butoxycarbonyl; Delta(Z) Nap: (Z)-beta-(1-naphthyl)dehydroalanine; OMe: methoxy] having the naphthyl group as a bulky beta substituent. Single crystals were grown by slow evaporation from an ethanol solution in the triclinic space group P1 with a = 9.528 (3) A, b = 12.410(4) A, c = 5.975(2) A, alpha = 96.77(3) degrees, beta = 102. 81(2) degrees, gamma = 88.74(3) degrees, V = 684.1(4) A3, and Z = 1. Phase determination was carried out by a direct method (SHELEXS), and the final structure was refined to R = 8.1% and R(w) = 9.0% for 1964 observed reflections. The bond lengths and bond angles of the Delta(Z)Nap residue, characterized by a sp(2) hybridized C(alpha) atom, did not differ from those of other dehydroresidues such as Delta(Z) Phe, Delta(Z) Leu, and DeltaVal essentially. The peptide backbone took a type II beta-turn conformation involving an intramolecular hydrogen bond between CO(Boc) and NH(Val), similar to di- or tripeptides containing a Delta(Z) Phe or Delta(Z) Leu residue in the second positions. Here the naphthyl group was found to be nonplanar [chi(2) = 55(1) degrees ] relative to the C(alpha)==C(beta)==C(gamma) plane. The nonplanarity was supported by conformational energy calculation. The molecular packing was stabilized by two kinds of intermolecular hydrogen bonds and van der Waals interactions. Naphthyl groups were arranged in a partially overlapped face-to-face orientation with a center-to-center distance of 5.97 A. For additional information, peptide Boc-(Ala-Delta(Z) Nap-Leu)(2)-OMe was synthesized and its solution conformation was investigated by (1)H-NMR spectroscopy. The hexapeptide showed the tendency to form a 3(10)-helical conformation in solution essentially. Conformational properties of Delta(Z) Nap residue, characterized by a type II beta-turn and 3(10)-helix, were supported by a conformational energy contour map of the Delta(Z)Nap residue.

[Ruptured aneurysm of sinus of Valsalva into the right atrium with aortic valve perforation].

A 58-year-old female was admitted to our hospital because of sudden dyspnea and general malaise. A continuous murmur was heard along the left sternal border. A chest X-ray showed cardiomegaly and pulmonary vascular marking. Doppler echocardiography confirmed the presence of an aneurysmatic mass, originating from the non-coronary sinus of Valsalva and extending to the right atrium, with a turbulent flow into the right atrium, aortic regurgitation (II/IV) and tricuspid regurgitation (III/IV). Ascending aortography demonstrated a communication between the aortic sinus and the right atrium. The pulmonary-to-systemic flow ratio was calculated to be 2.04. Oblique aortotomy and right atriotomy were performed. The aneurysm was resected and its origin was directly closed with horizontal mattress sutures through the aortic side and right atrial side. Perforation of a non-coronary cusp that caused aortic regurgitation was found following aortotomy and it was closed with an autologous pericardial patch. Tricuspid annuloplasty was performed using DeVega's technique. The postoperative course was uneventful, and she was discharged on the 10th postoperative day.

Cloning of an auxin-responsive 1-aminocyclopropane-1-carboxylate synthase gene (CMe-ACS2) from melon and the expression of ACS genes in etiolated melon seedlings and melon fruits.

Two cDNA fragments (pCMe-ACS2 and 3) encoding auxin-responsive 1-aminocyclopropane-1-carboxylate synthase (ACS; EC.4.4.1.14) have been isolated from melon, and the expression patterns of the genes in etiolated melon seedlings and melon fruit have been determined by RT-PCR analysis. The deduced amino acid sequences of pCMe-ACS2 and 3 were homologous to those of AT-ACS6 and 4, which were auxin-responsive ACS genes of Arabidopsis. Both CMe-ACS2 and 3 were auxin-responsive ACS genes and their expressions in roots and hypocotyls were induced by treatment with indole acetic acid (IAA, 100 µM). The mRNA level of CMe-ACS2 in the fruit increased after pollination. Those of both CMe-ACS2 and 3 temporarily increased in the mesocarp tissues at the preclimacteric stage (from day 3 to day 5 after harvest) during ripening, while that of CMe-ACS3 was lower than that of CMe-ACS2. The increase in the mRNA level of CMe-ACS1 (wound- and ripening-induced gene, T. Miki, M. Yamamoto, N. Nakagawa, O. Ogura, H. Mori, H. Imaseki, T. Sato, Nucleotide sequence of a cDNA for 1-aminocyclopropane-1-carboxylate synthase from melon fruits, Plant Physiol. 107 (1995) 297-298.) in the mesocarp tissue was not observed until 5 days after harvest. A genomic DNA encoding CMe-ACS2 was isolated and its nucleotide sequence was determined. Nucleotide sequences resembling the auxin-responsive elements (AuxRE) D1 and D4 (the TGTCTC element) in the GH3 gene from soybean, and the auxin-responsive domain (AuxRD) B in PS-IAA4/5 from pea were found in the 5'-flanking region of the CMe-ACS2 gene.

Localization and regulation of cytosolic phospholipase A(2).

Liberation of arachidonic acid by cytosolic phospholipase A(2) (cPLA(2)) upon cell activation is often the initial and rate-limiting step in leukotriene and prostaglandin biosynthesis. This review discusses the essential features of cPLA(2) isoforms and addresses intriguing insights into the catalytic and regulatory mechanisms. Gene expression, posttranslational modification and subcellular localization can regulate these isoforms. Translocation of cPLA(2)alpha from the cytosol to the perinuclear region in response to calcium transients is critical for the immediate arachidonic acid release. Therefore, particular emphasis is placed on the mechanism of the translocation and the role of the proteins and lipids implicated in this process. The regional distribution and cellular localization of cPLA(2) may help to better understand its function as an arachidonic acid supplier to downstream enzymes and as a regulator of specific cellular processes.

Splice variants of PAC(1) receptor during early neural development of rats.

The specific pituitary adenylate cyclase-activating polypeptide (PACAP) receptor, PAC(1)-R, consists of at least seven isoforms, and they are differentially coupled to signal transduction pathways by alternative splicing. We have found that the major splice variants of the PAC(1) receptor seen during development are the short splice isoform, PAC(1)-R-s (which does not contain either the "hip" or "hop" cassette), and another form, PAC(1)-R-hop (which contains the "hop" cassette). We also have applied an innovative molecular histochemical technique, in situ reverse transcription-polymerase chain reaction (RT-PCR), and determined that these two splice isoforms are colocalized in the neuroepithelia from the primitive streak stage.

Cloning, characterization and tissue distribution of the rat ATP-binding cassette (ABC) transporter ABC2/ABCA2.

The ABC1 (ABCA) subfamily of the ATP-binding cassette (ABC) transporter superfamily has a structural feature that distinguishes it from other ABC transporters. Here we report the cloning, molecular characterization and tissue distribution of ABC2/ABCA2, which belongs to the ABC1 subfamily. Rat ABC2 is a protein of 2434 amino acids that has 44.5%, 40.0% and 40.8% identity with mouse ABC1/ABCA1, human ABC3/ABCA3 and human ABCR/ABCA4 respectively. Immunoblot analysis showed that proteins of 260 and 250 kDa were detected in COS-1 cells transfected with ABC2 having a haemagglutinin tag, while no band was detected in mock-transfected cells. After incubation with N-glycosidase F, the mobilities of the two proteins increased and a single band was detected, suggesting that ABC2 is a glycoprotein. Photoaffinity labelling with 8-azido-[alpha-(32)P]ATP confirmed that ATP binds to the ABC2 protein in the presence of Mg(2+). RNA blot analysis showed that ABC2 mRNA is most abundant in rat brain. Examination of brain by in situ hybridization determined that ABC2 is expressed at high levels in the white matter, indicating that it is expressed in the oligodendrocytes. ABC2, therefore, is a glycosylated ABC transporter protein, and may play an especially important role in the brain. In addition, the N-terminal 60-amino-acid sequence of the human ABC1, which was missing from previous reports, has been determined.

Direct temperature-controlled trapping system and its use for the gas chromatographic determination of organic vapor released from human skin.

For controlling of trap temperature, the relationship between electric resistance of the trap tube and temperature is used. As the electric resistance of the trap tube (20 cm long stainless steel tubing) was very small, such as ca. 0.040 ohm for -70 degrees C and ca. 0.064 ohm for +90 degrees C, it was estimated by using the value of voltage output at both ends of the trap tube when a direct current (5 A) was applied for 6.5 ms at every 100 ms on the trap. By using this temperature measurement, a cycle of trapping is shortened, especially at the process of desorption, because it is possible to set a large increasing rate of temperature, such as 20 degrees C/s. The present trapping system has faster temperature response compared to that with a thermocouple. This system was applied for the study of the releasing of ethanol and water vapors from the human finger, which was treated as follows: dipping in 10% ethanol aqueous solution for 1 min, followed by washing with water and then drying in the air. In this case, a cycle of trapping took 53 s, and the period of total analysis was only 3 min. The present system is an efficient tool for the study of the exhalation of organic vapors from human skin.

Is endogenous isoprene the only coeluting compound in the measurement of breath pentane?

Pentane is a widely used index of lipid peroxidation. Although isopentane, an isomer of pentane, is a major component of ambient air in urban areas, many studies have disregarded the possibility that this compound is coeluted in the measurement of breath pentane. In the present study, a gas chromatograph equipped with a cold trap apparatus and a large-bore glass capillary column was used for determination of pentane, isopentane and isoprene in breath and ambient air. Isoprene was detected in all subjects at a concentration higher than that in the ambient air. However, the concentrations of breath pentane and isopentane were similar to, or less than, those of the ambient air. We suggest that great care is required in the measurement of breath pentane so that endogenous isoprene and ambient isopentane are not coeluted.

Synthesis of delta(E)Phe-containing tripeptide via photoisomerization and its conformation in solution.

A new synthetic route to (E)-beta-phenyl-alpha,beta-dehydroalanine (delta(E)Phe)-containing peptide was presented via photochemical isomerization of the corresponding (Z)-beta-phenyl-alpha,beta-dehydroalanine (delta(Z)Phe)-containing peptide. By applying this method to Boc-Ala-delta(Z)Phe-Val-OMe (Z-I: Boc, t-butoxycarbonyl; OMe, methoxy), Boc-Ala-delta(E)Phe-Val-OMe (E-I) was obtained. The identification of peptide E-I was evidenced by 1H-nmr, 13C-nmr, and uv absorption spectroscopy, elemental analysis, and hydrogenation. The conformation of peptide E-I in CDCl3 was investigated by 1H-nmr spectroscopy (solvent dependence of NH chemical shift and difference nuclear Overhauser effect). Interestingly, peptide E-I differed from peptide Z-I in the hydrogen-bonding mode. Namely, for peptide Z-I, only Val NH participates in intramolecular hydrogen bonding, which leads to a type II beta-turn conformation supported by hydrogen bonding between CO(Boc) and NH(Val). On the other hand, for peptide E-I, two NHs, delta(E)Phe NH and Val NH, participate in intramolecular hydrogen bonding. In both peptides, a remarkable NOE (approximately 11-13%) was observed for Ala C(alpha) H-deltaPhe NH pair. Based on the nmr data and conformational energy calculation, it should be concluded that peptide E-I takes two consecutive gamma-turn conformations supported by hydrogen bonding between CO(Boc) and NH(delta(E)Phe), and between CO(Ala) and NH(Val) as its plausible conformation.