Out-of-Plane Negative Magnetoresistance of Bi2Sr1.6La0.4CuO6+δ Single Crystals in the Underdoped Region

In order to investigate a relationship between the carrier concentration and negative magnetoresistance in the underdoped region, we have performed out-of-plane electrical resistivity measurements for underdoped Bi ₂ Sr _1.6 La _0.4 CuO ₆₊ single crystals. Giant negative magnetoresistance has been observed in the most abundant carrier sample with = 0.12 in our experiment. The negative magnetoresistance reduces with decreasing carrier concentration.     

Structural, Thermal and Electrical Properties of Ce-Doped SrMnO3

The Sr_1-xCe_xMnO_1- system (0 x 0.5) was investigated with respect to its structural, thermal and electrical properties. Although un-doped SrMnO₃ has the perovskite structure above 1400°C, the structure is unstable at room temperature. However, partial substitution of Ce for Sr in SrMnO₃ stabilizes the perovskite structure down to room temperature. Single phase perovskite is obtained for 0.1 x 0.3 in Sr_1-xCe_xMnO_1-, and it remains stable even following heat treatment at 800°C for 100 h. The dependence of the electrical conductivity on temperature was measured from room temperature to 1000°C in air. Ce doping dramatically enhanced the electrical conductivity of SrMnO₃. Sr_0.7Ce_0.3MnO_1- exhibits a higher conductivity (290 S · cm^-1 at 1000°C) than that of La_0.8Sr_0.2MnO₃ (LSM, about 175 S · cm^-1) and remains n-type over the whole range of temperature examined. The thermal expansion coefficients in the system were nearly constant with values ranging between 1.24 × 10^-6 and 1.01 × 10^-6 cm/cm · K for temperatures of 50°C to 1000°C.     

Immediate-type heat urticaria: report of a case and study of plasma histamine release

We report a 68-year-old man who had immediate-type heat urticaria with systemic symptoms. Immersing his hand in water at 42 degrees C (heat challenge test) produced an urticarial response, with an increase in the plasma histamine level from 0.26 to 7.64 ng/mL. Administration of oral antihistamines alone did not suppress either the urticarial response or the increase in plasma histamine. However, a combination of antihistamines and desensitization improved the skin lesions and reduced the plasma histamine level. The heat challenge test subsequently provoked a negative response and there was no increase in plasma histamine level 3 months after starting the combination therapy. These results indicate that the histamine level reflected the result of the heat challenge test and the amelioration of the skin eruption.     

Induction of ectopic corticotropic tumor in mouse embryos by exo utero cell transplantation and its effects on the fetal adrenal gland

To establish an in vivo experimental system for developmental endocrinology research, AtT-20 cells, a corticotropic tumor cell line, were transplanted by exo utero manipulation into mouse embryos on embryonic day 14. The induced tumor secreted ACTH in situ, and the circulating ACTH level was elevated. This was the first model for studying the regulation of ACTH in the mouse fetal adrenal in vivo and the first continuous ACTH treatment model in rodent fetuses. The changes in the adrenal gland from the tumor-induced embryos were analyzed by light microscopic morphometry, immunohistochemistry for steroidogenic enzymes, and electron microscopy. In the treated adrenal, the volume of the inner cortical zone was significantly larger than that in controls. In the inner zone, cell density was decreased, and average cell size was increased, whereas bromodeoxyuridine-incorporation was not increased. The enlarged inner zone cells expressed an enhanced level of cytochrome P45011beta, the corticosterone-synthesizing enzyme, and the serum corticosterone level was increased. Electron microscopy showed an active form of the organelles involved in steroidogenesis. These findings indicate that ACTH stimulates both adrenocortical hypertrophy and steroidogenesis in fetal mice. Potential perspectives of the novel paradigm in this research for molecular developmental endocrine study are discussed.     

A patient with acromegalic heart disease--a case report

A perioperative anesthetic management of a 69 year old woman with acromegaly whose clinical course was characterized by severe heart failure is described. The patient showed symptoms of massive cardiomegaly. Endocrine studies indicated that her pituitary tumor was active with hyperproduction of growth hormone. There was no demonstrable evidence for other known causes of heart disease. Following hormonal therapy using continuous subcutaneous infusion of somatostatin for about two months, there was improvement in daily activity and reduction in heart size. After the improvement of cardiac function, transsphenoidal hypophysectomy was performed under general anesthesia and its perioperative course was quite uneventful. We conclude that because cardiac involvement such as left ventricular dilatation in acromegaly might be reversible with proper treatment, any surgical procedure, as long as the case is elective, should be considered after hormone therapy.     

An XPS study of the surfaces on Fe-Cr,Fe-Co and Fe-Ni alloys after mechanical polishing

Using an XPS technique, the composition and thickness of the surface film and the composition of the underlying alloy surface on Fe-Cr, Fe-Co and Fe-Ni alloys were studied after polishing with silicon carbide paper in trichloro-ethylene and cyclohexane. The compositions of the underlying alloy surface after polishing were almost the same as those of the bulk alloys but the film compositions depended on the alloying addition and environment during polishing. The cationic fractions in the surface films on the Fc-Cr alloys polished in both solvents were almost the same as the corresponding atomic fractions of the bulk alloys. In contrast, iron ions were apt to be concentrated in the surface films on the Fe-Co and Fe-Ni alloys, and the weights of nickel ions were different in the surface films on the Fe-Ni alloys polished in different solvents. Chloride ions were found in the surface films due to the reaction of the metal surface with trichloro-ethylene. The amount of chloride ions was particularly large in the surface films on the Fe-Ni alloys. Heating the alloy specimens under the vacuum of the spectrometer resulted in almost complete reduction of the surface films on the Fe-Co and Fe-Ni alloys, and in the change in the compositions of all alloy surfaces.     

Specific isoprenyl group linked to transducin gamma-subunit is a determinant of its unique signaling properties among G-proteins

Among 11 subtypes of heterotrimeric G-protein gamma-subunit, gamma1 (rod), gamma8 (cone) and gamma11 are modified with farnesyl while the others are modified with geranylgeranyl at the C-terminus. To understand the role of specific isoprenylation (farnesylation) of retinal transducin, we examined how and to what extent the type of isoprenyl group affects transducin-beta gamma (beta1 gamma1) functions such as interactions with membranes, Galpha/receptor, and effectors. To this end, the C-terminal farnesylation signal sequence (CVIS) of gamma1 was replaced by a geranylgeranylation signal (CVIL), and the resultant mutant (S74L) or wild-type (WT) gamma1 was coexpressed with beta1 in the baculovirus-Tn5 insect cell system. Both gamma1WT and gamma1S74L expressed as a beta gamma complex were mixtures modified with farnesyl and geranylgeranyl groups. The ratio of farnesyl to geranylgeranyl in preparations of beta1 gamma1WT and beta1 gamma1S74L purified from the Tn5 cell membrane fraction was about 1:2 and 1:6, respectively. These two forms of recombinant beta1 gamma1 and retinal beta1 gamma1 were different in their abilities to associate with rod outer segment membranes with the following rank order: beta1 gamma1S74L > beta1 gamma1WT > retinal beta1 gamma1. Functionally, beta1 gamma1S74L was the most potent to promote pertussis toxin-catalyzed ADP ribosylation of transducin-alpha (Talpha), to stimulate metarhodopsin II-catalyzed GTPgammaS-binding reaction to Talpha and to modulate adenylyl cyclase and phospholipase C activities. All of the beta1 gamma1 functions absolutely required the isoprenylation of the gamma-subunit. As for the interaction with Goalpha and adenylyl cyclase, predominantly geranylgeranylated beta1 gamma1S74L was less effective than geranylgeranylated beta1 gamma2 purified from bovine brain. These results demonstrate that the properties of Gbeta gamma are strongly affected by the type of functionally indispensable isoprenylation in addition to the amino acid sequence of Ggamma. The relative contribution of the two factors depends on proteins with which Gbeta gamma interacts.