Promoting Effect of Pt on Self-activation over NiO–MgO Solid Solution in Oxidative Steam Reforming of Methane

The addition of Pt on NiO–MgO solid solution enhanced the performance of oxidative steam reforming of methane, especially, the catalyst can be activated during the oxidative reforming of methane at low reaction temperature like 823 K. 0.1% Pt/Ni_0.2Mg_0.8O exhibited much higher performance than 0.1% Pt/MgO and Ni_0.2Mg_0.8O. From the comparisons, the additive effect of Pt to Ni_0.2Mg_0.8O is to promote both the activity of combustion and reforming of methane. This additive effect can be explained by the high combustion activity caused by the synergy of Pt with NiO–MgO solid solution and the high catalyst reducibility.     

Dietary eritadenine-induced alteration of molecular species composition of phospholipids in rats

The effect of dietary eritadenine, a hypocholesterolemic compound found in the mushroomLentinus edodes, on the fatty acid and molecular species profiles of phosphatidylcholine (PC) and phosphatidylethanolamine (PE) in the plasma and liver microsomes was investigated in relation to the hypocholesterolemic action of the compound in rats. Animals were fed the control or eritadenine-supplemented (50 mg/kg diet) diet for 14 d. Eritadenine supplementation significantly decreased the plasma concentrations of cholesterol and phospholipids, but not triglycerides. The PC/PE ratio of liver microsomes, but not plasma, was also markedly decreased by eritadenine. Eritadenine supplementation was found to increase the proportion of 18:2n-6 and, inversely, to decrease the proportion of 20:4n-6 and 22:5n-6 in plasma PC and liver microsomal PC and PE, indicating that eritadenine depressed the metabolism of linoleic acid. The effect of eritadenine on the profile of n-3 fatty acids was dissimilar in PC and PE. These changes in fatty acid composition were selectively reflected in the molecular species composition of both PC and PE; the extent of increase in 16:0–18:2 molecular species or decrease in 18:0–20:4 molecular species was apparently greater than that of other molecular species containing 18:2 or 20:4 in the sn-2 position. These results suggest that, in addition to the decrease in liver microsomal PC/PE ratio, the alteration of plasma PC molecular species composition might also participate in the hypocholesterolemic action of eritadenine.     

Prolonged degradation of end-capped polyelectrolyte multilayer films

Cationic chitosan (CT) and anionic dextran sulfate (Dex) were layer-by-layer (LbL) assembled from aqueous solutions containing 1 M NaCl on a quartz crystal microbalance (QCM) substrate, and the original films ((CT-Dex)₃-CT)) were end-capped with LbL assembly from CT solutions containing 1 M NaCl and Dex solutions without NaCl. The enzymatic degradation of films by chitosanase was quantitatively analyzed by QCM in terms of numbers of end-capping steps. The degradation of films end-capped with (Dex-CT)₃ was considerably prolonged when compared to those end-capped with other end-capping steps. A mechanism for the prolonged degradation was proposed by quantitative QCM data and zeta potential results.     

Diphtheria toxin binds to the epidermal growth factor (EGF)-like domain of human heparin-binding EGF-like growth factor/diphtheria toxin receptor and inhibits specifically its mitogenic activity

The membrane anchored form of human heparin-binding epidermal growth factor-like growth factor (HB-EGF) acts as the diphtheria toxin (DT) receptor. Transfection of human HB-EGF cDNA into mouse LC cells, L cells stably expressing DRAP27, conferred sensitivity to DT, but transfection of mouse HB-EGF cDNA did not. To define the essential regions of HB-EGF that serve as the functional DT receptor, we examined the sensitivity to DT and DT binding of cells expressing several human/mouse HB-EGF chimeras. It was found that DT binds to the EGF-like domain of the human HB-EGF. However, mouse HB-EGF does not serve as a functional DT receptor due to non-conserved amino acid substitutions in this domain. In addition, CRM197, a non-toxic mutant of DT, inhibited strongly the mitogenic activity of the secreted form of human HB-EGF, but not of mouse HB-EGF and other EGF receptor-binding growth factors. These results confirmed further that DT interacts with the EGF-like domain of HB-EGF and that this interaction is specific for human HB-EGF.     

Environmental isolation of Cryptococcus neoformans from an endemic region of HIV-associated cryptococcosis in Thailand

We successfully isolated Cryptococcus neoformans from chicken faeces in suburban areas of Thailand. C. neoformans was isolated from 36/150 houses (24.0%) in the dry season and 6/150 (4.0%) in the rainy season. All environmental isolates were of serotype A. The high isolation rate of 24% from chicken faeces has never been reported previously. Our environmental study could probably explain the high incidence of cryptococcal meningitis in HIV patients in Thailand.     

Enzymatic enrichment of arachidonic acid from Mortierella single-cell oil

An attempt was made to enrich arachidonic acid (AA) from Mortierella single-cell oil, which had an AA content of 25%. The first step involved the hydrolysis of the oil with Pseudomonas sp. lipase. A mixture of 2.5 g oil, 2.5 g water, and 4000 units (U) Pseudomonas lipase was incubated at 40°C for 40 h with stirring at 500 rpm. The hydrolysis was 90% complete after 40 h, and the resulting free fatty acids (FFA) were extracted with n-hexane (AA content, 25%; recovery of AA, 91%). The second step involved the selective esterification of the fatty acids with lauryl alcohol and Candida rugosa lipase. A mixture of 3.5 g fatty acids/lauryl alcohol (1:1, mol/mol), 1.5 g water, and 1000 U Candida lipase was incubated at 30°C for 16 h with stirring at 500 rpm. Under these conditions, 55% of the fatty acids were esterified, and the AA content in the FFA fraction was raised to 51% with a 92% yield. The long-chain saturated fatty acids in the FFA fraction were eliminated as urea adducts. This procedure raised the AA content to 63%. To further elevate the AA content, the fatty acids were esterified again in the same manner with Candida lipase. The repeated esterification raised the AA content to 75% with a recovery of 71% of its initial content.     

Elevation of plasma levels of L-dopa in transdermal administration of L-dopa-butylester in rats

To increase delivery of L-dopa in its transdermal absorption, a new lipophilic derivative of L-dopa, L-dopa-butylester, was synthesized. An in-vitro study employing two-chamber diffusion cells, in which the excised rat abdominal skin was mounted, revealed that, in the presence of L-menthol and ethanol, L-dopa-butylester penetrated in its original form more effectively than L-dopa. L-Dopa-butylester sheets were made by immersing wiper sheets in methanol containing the compound, and then evaporating the methanol. An extraction study of the compound from the sheets revealed that its stability was maintained for at least 12 weeks. In an in-vivo cutaneous absorption study, an L-dopa-butylester sheet was attached to the shaved rat abdominal skin. A hydrogel containing L-menthol and ethanol was spread on vinyl tape, and this sheet was placed over it. In plasma, the L-dopa level rose linearly between 30 and 180 min after the cutaneous application; L-dopa-butylester was not detected. The L-dopa level was higher than that in which L-dopa was applied. These findings indicated that the lipophilic nature of L-dopa-butylester further increased its penetration through the skin, and that L-dopa-butylester that was taken up into the general circulation system was rapidly converted to L-dopa by hydrolysis in the body.     

Epitaxial growth of titanium oxide thin films on MgO(100) single-crystal substrates by reactive deposition methods

We synthesized titanium oxide thin films on MgO(100) single-crystal substrates by two reactive deposition methods and compared the structures of the thin films formed by these methods. In one method (pulsed-molecular-beam deposition method), molecular oxygen is supplied to the substrates by using a pulsed-molecular-oxygen beam source and deposition of one unit layer of titanium and subsequent supply of molecular oxygen are repeatedly performed. In the other method (radical beam deposition method), atomic oxygen is irradiated to the substrates by using an atomic oxygen beam generated by the radical beam source and irradiation of the atomic oxygen and deposition of titanium are simultaneously performed. In the case of the pulsed-molecular-beam deposition method, the crystal structure was changed by increasing the number of oxygen pulses supplied from the beam source. We found that the crystal structure of titanium oxide depended on the composition ratio of O:Ti in the film. The maximum ratio of O:Ti attainable by this method was 1.85, and at this ratio, (100)-oriented pseudorutile was formed. In the case of the radical beam deposition method, (100)-oriented anatase was formed below the titanium deposition rate of 0.10 nm/s and pseudorutile (TiO_2−δ) was formed above 0.15 nm/s. The pseudorutile structure synthesized on this experiment was very stable in air. We concluded that the crystal structure of the pseudorutile is a new crystal structure of titanium oxide.     

Simultaneous manifestation of squamous cell carcinoma in identical twins with epidermolysis bullosa

We report a case of identical twins with recessive dystrophic epidermolysis bullosa, who developed squamous cell carcinoma in the hand at the latter half of their third decade. To our knowledge, this is the first case of manifestation of squamous cell carcinoma in identical twins and may contribute to the understanding of oncogenesis in such patients.     

Exaggerated urinary excretion of aquaporin-2 in the pathological state of impaired water excretion dependent upon arginine vasopressin

The present study was undertaken to determine whether urinary excretion of aquaporin-2 (UAQP-2) is of value to diagnose the pathological state of water retention and hyponatremia. UAQP-2 under ad libitum water drinking was 429 fmol/mg creatinine in the patients with water retention, a value significantly greater than that of 153 fmol/mg creatinine in the normal subjects. An acute oral water load test (20 mL/kg BW) was performed in 7 normal subjects (22-25 yr old) and 10 patients with water retention and hyponatremia (55-75 yr old). The percent excretion of the water load was only 30% in the patient group compared with 70% in the control group (P < 0.01). In the control group, minimal urinary osmolality was as low as 131 mosmol/kg H2O, which was responsible for the decrease in plasma arginine vasopressin (AVP) levels after the reduction in plasma osmolality. In the patient group, minimal urinary osmolality was 320 mosmol/kg H2O, and free water clearance remained below 0.6 mL/min after the water load. This impaired water excretion was consistent with the nonsuppressible levels of plasma AVP despite hypoosmolality. The nadir of UAQP-2 was obtained at 60-90 min. The minimal UAQP-2 was reduced to 284 fmol/mg creatinine, a value significantly greater than that of 76 fmol/mg creatinine in the control group. Similar results were obtained in the 6 patients with hypopituitarism, who had impaired water excretion and marked hyponatremia. Water excretion was totally normalized after the replacement of hydrocortisone (excretion of water load, 31% vs. 102%; P < 0.01). Hydrocortisone replacement also significantly reduced the minimal UAQP-2 from 225 to 49 fmol/mg creatinine after the acute oral water load, a value comparable to that in the control subjects. These results indicate that UAQP-2 is a potent marker to diagnose the pathological state of impaired water excretion and hyponatremia, dependent upon AVP, in patients with water retention and hypopituitarism.