Differential activity of the G protein beta5 gamma2 subunit at receptors and effectors

The G protein beta5 subunit differs substantially in amino acid sequence from the other known beta subunits suggesting that beta gamma dimers containing this protein may play specialized roles in cell signaling. To examine the functional properties of the beta5 subunit, recombinant beta5 gamma2 dimers were purified from baculovirus-infected Sf9 insect cells using a strategy based on two affinity tags (hexahistidine and FLAG) engineered into the N terminus of the gamma2 subunit (gamma2HF). The function of the pure beta5 gamma2HF dimers was examined in three assays: activation of pure phospholipase C-beta in lipid vesicles; activation of recombinant, type II adenylyl cyclase expressed in Sf9 cell membranes; and coupling of alpha subunits to the endothelin B (ETB) and M1 muscarinic receptors. In each case, the efficacy of the beta5 gamma2HF dimer was compared with that of the beta1 gamma2HF dimer, which has demonstrated activity in these assays. The beta5 gamma2HF dimer activated phospholipase C-beta with a potency and efficacy similar to that of beta1 gamma2 or beta1 gamma2HF; however, it was markedly less effective than the beta1 gamma2HF or beta1 gamma2 dimer in its ability to activate type II adenylyl cyclase (EC50 of approximately 700 nM versus 25 nM). Both the beta5 gamma2HF and the beta1 gamma2HF dimers supported coupling of M1 muscarinic receptors to the Gq alpha subunit. The ETB receptor coupled effectively to both the Gi and Gq alpha subunits in the presence of the beta1 gamma2HF dimer. In contrast, the beta5 gamma2HF dimer only supported coupling of the Gq alpha subunits to the ETB receptor and did not support coupling of the Gi alpha subunit. These results suggest that the beta5 gamma2HF dimer binds selectively to Gq alpha subunits and does not activate the same set of effectors as dimers containing the beta1 subunit. Overall, the data support a specialized role for the beta5 subunit in cell signaling.     

Organ donation from the viewpoint of the medical students

A questionnaire survey was carried out to examine the attitudes of 125 medical students, aged 19-37 years, toward organ donation. 73 of them were in their first semester and 52 senior students in their last year of the study. A return rate of 88% (senior students: 58%) was achieved. Although 59% (71%) expressed willingness to donate their organs, only 30% (50%) had signed an organ donor card. Concerns regarding definition and declaration of death, benefit of organ donation and feelings of the donor's family were identified in 51% (38%) of the students. 71% (79%) had already discussed this issue with their families. In summary, results of the study indicate that more intensified interdisciplinary discussion and information during the study of medicine could bring about an even more positive attitude toward organ donation.     

A case of eosinophilic pustular folliculitis (Ofuji's disease) induced by patch and challenge tests with indeloxazine hydrochloride

A 73-year-old male developed disseminated erythema over his entire body after exposure to indeloxazine hydrochloride, a cerebral activator. Patch testing with indeloxazine hydrochloride showed a positive reaction, and plaques, vesicles and pustules developed on the face after the patch test. These had the pathologic feature of eosinophilic pustular folliculitis (EPF, Ofuji's disease). A challenge test also provoked eruptions on the face, trunk, arms and legs, which were compatible with EPF. Moreover, both the patch and challenge tests with indeloxazine hydrochloride induced eosinophilia. This is the first report of drug allergy-induced EPF, where drug sensitivity induced an abnormal eosinophilic response mimicking EPF.     

Compatibilizing PPE and PA6 with nitro-phthalimide derivatives

Compatibilization of poly(2,6-dimethyl (PPE) with 1,4 phenylene-ether) PA6 has been achieved in two steps: first, (PPE) was functionalized with N-methyl-4-nitro-phthalimide; then, functionalized PPE was allowed to react, by melt blending, with the amine end group of PA6, giving a trans-imidation product. The reaction path was followed by torque measurements in a Brabender apparatus and the products characterized by infrared (i.r.) and nuclear magnetic resonance (NMR) spectroscopy. The above PPE/PA6 blends, modified with a suitable rubbery component (Kraton G), showed a remarkable Izod impact strength value, compared to the uncompatibilized mixture (170 versus 30 Jm^–1). The maximum impact values were obtained with 1.65% functionalized PPE.     

Inertia-friction welding of SiC-reinforced 8009 aluminium

Inertia-drive friction welding (IFRW) of an 8009 Al alloy (Al-8.5 Fe-1.7 Si-1.3 V, wt%) reinforced with 11 volume per cent SiC particles (8009/SiC/11_p) has been investigated. Inertia-drive friction welds were made with constant energy at two levels of axial force. The microstructures of the base material and the welds were characterized using optical and scanning electron microscopy, while the mechanical properties were evaluated using microhardness and tensile testing. Examination of weld sections revealed that the hot deformation experienced during welding produced a homogenized microstructure with a uniform distribution of SiC particles along the bond line. No evidence of a chemical reaction between the SiC and the matrix was found in any of the welds, but cracking of some of the larger SiC particles was observed in the base material as well as in the IFR welds. The average microhardness of the various heat-and-deformation affected zones (HDZs) of the welds did not vary greatly from that of the base material, and no weld induced weak regions were discerned. The room-temperature (RT) tensile strength of the IFR welds exceeded 90 per cent of the base material. The weld tensile specimens failed at the outer edge of the HDZ for all of the welds tested. The fracture surface of the 8009 matrix of tensile samples for both the base material and the welds exhibited a dimpled appearance indicating a ductile failure, while fracture through the SiC appeared to occur in a brittle fashion. IFRW has proven effective in joining 8009/SiC/11_p with little loss in RT hardness and tensile properties.