Thermotropic and Barotropic Phase Behavior of Phosphatidylcholine Bilayers

Bilayers formed by phospholipids are frequently used as model biological membranes in various life science studies. A characteristic feature of phospholipid bilayers is to undergo a structural change called a phase transition in response to environmental changes of their surroundings. In this review, we focus our attention on phase transitions of some major phospholipids contained in biological membranes, phosphatidylcholines (PCs), depending on temperature and pressure. Bilayers of dipalmitoylphosphatidylcholine (DPPC), which is the most representative lipid in model membrane studies, will first be explained. Then, the bilayer phase behavior of various kinds of PCs with different molecular structures is revealed from the temperature–pressure phase diagrams, and the difference in phase stability among these PC bilayers is discussed in connection with the molecular structure of the PC molecules. Furthermore, the solvent effect on the phase behavior is also described briefly.     

Microwave synthesis of Fe-doped β-rhombohedral boron

Iron-doped β-rhombohedral boron was synthesized by 28 GHz microwave irradiation on a powder mixture of iron and β-boron. β-Boron strongly absorbs 28 GHz microwaves, and this strong coupling with microwave energy can be used to promote a reaction with iron dopant. The powder mixture was heated to 1800°C within 2 min by microwave irradiation, resulting in the formation of β-rhombohedral boron interstitially doped with iron. The reaction proceeded rapidly without accompanying grain growth. The XRD analysis and the electrical conductivity measurements revealed successful incorporation of iron into two doping sites of β-boron.     

The use of intraoperative ultrasonography for detecting tumor extension in bile duct carcinoma

This study examined the intraoral changes of the elastic properties and roughness of a tissue conditioner after treatment with a fluorinated copolymer coating agent developed by the authors. The surface of the conditioner was treated with the agent on half of the internal surface of five maxillary complete dentures and was compared with the untreated half on the other side. The cushioning effects of the conditioners were evaluated by measuring the creep compliance strain-to-stress ratio. The value of compliance on the treated half was significantly greater than that on the untreated half. There was significantly less roughness on the treated side than on the untreated side. It was found that the coating provides an improved, glossy surface to the conditioner and may increase its useful life.     

Contemporary percutaneous treatment of unprotected left main coronary stenoses: initial results from a multicenter registry analysis 1994-1996

BACKGROUND: Coronary artery bypass surgery (CABG) has been considered the therapy of choice for patients with unprotected left main (ULMT) coronary stenoses. Selected single-center reports suggest that the results of percutaneous intervention may now approach those of CABG. METHODS AND RESULTS: To assess the results of percutaneous ULMT treatment from a wide variety of experienced interventional centers, we requested data on consecutive patients treated after January 1, 1994, from 25 centers. One hundred seven patients were identified who were treated either electively (n=91) or for acute myocardial infarction (n=16). Of patients treated electively, 25% were considered inoperable, and 27% were considered high risk for bypass surgery. Primary treatment included stents (50%), directional atherectomy (24%), and balloon angioplasty (20%). Follow-up was 98.8% complete at 15+/-8 months. Results varied considerably, depending on presentation and treatment. For patients with acute myocardial infarction, technical success was achieved in 75%, and survival to hospital discharge was 31%. For elective patients, technical success was achieved in 98.9%, and in-hospital survival was strongly correlated with left ventricular ejection fraction (P=.003). Longer-term event (death, infarction, or bypass surgery) -free survival was correlated with ejection fraction (P<.001) and was inversely related to presentation with progressive or rest angina (P<.001). Surgical candidates with ejection fractions > or = 40% had an in-hospital survival of 98% and a 9-month event-free survival of 86+/-5%, whereas patients with ejection fractions < 40% had 67% and 22+/-12% in-hospital and 9-month event-free survivals, respectively. Nine hospital survivors (10.6%) experienced cardiac death within 6 months of hospital discharge. CONCLUSIONS: While results for selected patients appear promising, until early post-hospital discharge cardiac death can be better understood and minimized, percutaneous revascularization of ULMT stenosis should not be considered an alternative to bypass surgery for most patients. When percutaneous revascularization of ULMT is required, directional atherectomy and stenting appear to be the preferred techniques, and follow-up angiography 6 to 8 weeks after treatment is probably advisable.     

Radiographic analysis of hallux valgus in women on weightbearing and nonweightbearing

To investigate changes in the radiographic appearance during weightbearing in hallux valgus and to examine the importance of a weightbearing view, a comparative study was performed of accurate dorsoplantar radiographs of 108 symptomatic hallux valgus feet in 73 female patients and 100 normal feet in 69 females, which were taken weightbearing and nonweightbearing. The hallux valgus angle in the hallux valgus group increased on weightbearing, whereas that in the normal group decreased. The intermetatarsal angle between the first and second metatarsals increased on weightbearing in both groups. The degree of the changes of the angles was closely related with the degree of the hallux valgus deformity. The intermetatarsal angle between the fourth and fifth metatarsals decreased on weightbearing in the both groups. A weightbearing view is necessary to evaluate the structural configuration of hallux valgus, because muscle imbalance around the first metatarsophalangeal joint in hallux valgus causes an increase of a hallux valgus angle on weightbearing.     

Characterization of plasma membrane proton-ATPase from salt-tolerant yeast Zygosaccharomyces rouxii cells

Plasma membrane was isolated from the salt-tolerant yeast Zygosaccharomyces rouxii and from Saccharomyces cerevisiae. The ATPase in the plasma membrane of Z. rouxii cells was a typical proton-ATPase as judged by testing with various ATPase inhibitors. There were slight differences in the pH optima of activities and in the sensitivity to sodium chloride (NaCl) and potassium chloride (KCl) of the ATPase from Z. rouxii and S. cerevisiae. The specific ATPase activity from Z. rouxii was higher in cells grown in a medium containing 2 _M-NaCl than in those not containing NaCl. No in vivo activation by incubation with glucose was observed in Z. rouxii cells and the specific ATPase activity was independent of the growth phase, unlike S. cerevisiae cells.     

Low-Thermal-Expansion Properties of Sodium- and Lithium-Substituted Cubic Cesium Leucite Compounds

Cubic cesium leucite-based compounds, namely cesium leucites, cesium sodium leucites, and cesium lithium leucites, were synthesized using a multistep solid-state reaction method. The thermal expansion properties, in the temperature range of 298-1273 K, for the synthesized cubic cesium leucite-based compounds were examined using high-temperature powder X-ray diffractometry data. The thermal expansions of the cubic cesium leucite-based compounds were found to vary with the chemical composition. For instance, the thermal expansions of Cs_0.7Na_0.2Al_0.9Si_2.1O₆ and Cs_0.7Li_0.2Al_0.9Si_2.1O₆ were 0.14% at 1273 K and 0.081% at 1073 K, values lower than those of Cs_0.9Al_0.9Si_2.1O₆, which were 0.16% at 1073 K and 0.2% at 1273 K. The results showed that the thermal expansions of the cubic cesium leucite-based compounds changed with ionic substitution at the Cs⁺ sites because of ionic size differences between Cs⁺ and the Na⁺ or Li⁺ substitutional ions.     

Preparation of fine polymer particles containing metallocene derivatives

This article deals with preparations of fine particles of metallocene copolymers by emulsifierfree emulsion polymerization of vinylferrocene (VFc), ferrocenylmethyl methacrylate (FMMA), 1-ferrocenylethyl methacrylate (1-FEMA), 2-ferrocenylethyl methacrylate (2-FEMA), and 1-ruthenocenylethyl methacrylate (1-REMA) with acrylonitrile (AN), styrene (St), and methyl methacrylate (MMA) in water/ethanol medium. As a result, spherical copolymer particles containing metallocene derivatives have been successfully synthesized in the particle size of ca. 120 to 600 nm. The contents of ferrocenyl or ruthenocenyl groups in copolymer particles increased with increasing concentration of charged metallocene derivatives, while the amounts of metallocene derivatives incorporated into particles are much lower than the charged ratio. © 1994 John Wiley & Sons, Inc.     

Reconstitution of hepatic tissue architectures from fetal liver cells obtained from a three-dimensional culture with a rotating wall vessel bioreactor

Reconstitution of tissue architecture in vitro is important because it enables researchers to investigate the interactions and mutual relationships between cells and cellular signals involved in the three-dimensional (3D) construction of tissues. To date, in vitro methods for producing tissues with highly ordered structure and high levels of function have met with limited success although a variety of 3D culture systems have been investigated. In this study, we reconstituted functional hepatic tissue including mature hepatocyte and blood vessel-like structures accompanied with bile duct-like structures from E15.5 fetal liver cells, which contained more hepatic stem/progenitor cells comparing with neonatal liver cells. The culture was performed in a simulated microgravity environment produced by a rotating wall vessel (RWV) bioreactor. The hepatocytes in the reconstituted 3D tissue were found to be capable of producing albumin and storing glycogen. Additionally, bile canaliculi between hepatocytes, characteristics of adult hepatocyte in vivo were also formed. Apart from this, bile duct structure secreting mucin was shown to form complicated tubular branches. Furthermore, gene expression analysis by semi-quantitative RT-PCR revealed the elevated levels of mature hepatocyte markers as well as genes with the hepatic function. With RWV culture system, we could produce functionally reconstituted liver tissue and this might be useful in pharmaceutical industry including drug screening and testing and other applications such as an alternative approach to experimental animals.