Fermi surface nesting induced strong pairing in iron-based superconductors.

The discovery of high-temperature superconductivity in iron pnictides raised the possibility of an unconventional superconducting mechanism in multiband materials. The observation of Fermi-surface (FS)-dependent nodeless superconducting gaps suggested that inter-FS interactions may play a crucial role in superconducting pairing. In the optimally hole-doped Ba(0.6)K(0.4)Fe(2)As(2), the pairing strength is enhanced simultaneously (2Delta/T(c) approximately 7) on the nearly nested FS pockets, i.e., the inner hole-like (alpha) FS and the 2 hybridized electron-like FSs, whereas the pairing remains weak (2Delta/T(c) approximately 3.6) in the poorly nested outer hole-like (beta) FS. Here, we report that in the electron-doped BaFe(1.85)Co(0.15)As(2), the FS nesting condition switches from the alpha to the beta FS due to the opposite size changes for hole- and electron-like FSs upon electron doping. The strong pairing strength (2Delta/T(c) approximately 6) is also found to switch to the nested beta FS, indicating an intimate connection between FS nesting and superconducting pairing, and strongly supporting the inter-FS pairing mechanism in the iron-based superconductors.

Observation of Dirac cone electronic dispersion in BaFe2As2.

We performed an angle-resolved photoemission spectroscopy study of BaFe2As2, which is the parent compound of the so-called 122 phase of the iron-pnictide high-temperature superconductors. We reveal the existence of a Dirac cone in the electronic structure of this material below the spin-density-wave temperature, which is responsible for small spots of high photoemission intensity at the Fermi level. Our analysis suggests that the cone is slightly anisotropic and its apex is located very near the Fermi level, leading to tiny Fermi surface pockets. The bands forming the cone show an anisotropic leading edge gap away from the cone that suggests a nodal spin-density-wave description.

Multiequilibrium binding of a spin-labeled local anesthetic in phosphatidylcholine bilayers.

The equilibria among spin-labeled amine local anesthetic species in dioleoylphosphatidylcholine liposomes at an anesthetic: lipid mole ratio of 1:100 are investigated. Electron spin resonance (ESR) spectra demonstrate that anesthetic mobility within the bilayer is charge-dependent, with the uncharged species the more mobile. Partition coefficient measurements confirm ESR evidence that changes in anesthetic mobility represent anesthetic-phospholipid interaction and not changes in bilayer fluidity. Spin-exchange attenuation experiments show that anesthetics within the bilayer are accessible to the aqueous medium. Dependence of tertiary-amine anesthetic pK on dielectric constant has been used to estimate the interfacial pK. We propose a model of equilibria among species of the tertiary amine anesthetic in the aqueous medium and those intercalated in the bilayer, including a species electrostatically bound to the lipid phosphate. Using experimentally determined equilibrium constants, the model provides the binding constant between the electrostatically bound and unbound cationic anesthetics within the bilayer. The model stimulates the pH dependence of the mobile fraction of total anesthetic population determined by subtraction techniques on experimental ESR spectra.

Protein Synthesis and Breakdown during Heat Shock of Cultured Pear (Pyrus communis L.) Cells.

Cultured pear (Pyrus communis L. cv Passe Crassane) cells were subjected to temperatures of 39, 42, and 45[deg]C. Heat-shock protein (hsp) synthesis was greater at 30[deg]C than at temperatures above 40[deg]C and continued for up to 8 h. Both cellular uptake of radiolabeled methionine and total protein synthesis were progressively lower as the temperature was increased. Polysome levels decreased immediately when cells were placed at 39 or 42[deg]C, although at 39[deg]C the levels began to recover after 1 h. In cells from both temperatures, reassembly occurred after transfer of cells to 25[deg]C Four heat-shock-related mRNAs[mdash]hsp17, hsp70, and those of two ubiquitin genes[mdash]all showed greatest abundance at 39[deg]C and decreased at higher temperatures. Protein degradation increased with time at 42 and 45[deg]C, but at 39[deg]C it increased for the first 2 h and then decreased. In the presence of cycloheximide, which prevented hsp synthesis, protein degradation at 39[deg]C was as great as that at 45[deg]C in the absence of cycloheximide. The data suggest that hsps may have a role in protecting proteins from degradation at the permissive temperature of 39[deg]C. At temperatures high enough to inhibit hsp synthesis, protein degradation was enhanced. Although ubiquitin may play a role in specific protein degradation, it does not appear to be involved in increased protein degradation occurring above 40[deg]C.

Bronchial collapse in obstructive lung disease.

A 57-year-old man who died suddenly with severe bilateral mainstem bronchial collapse is described, and an alteration of the elastic tissue in the membranous portion of the bronchi is identified. The morphologic abnormalities, physiologic dynamics, and potential clinical consequences of such an alteration are discussed.

Evaluation of a pectin agar medium for isolation of Yersinia enterocolitica within 48 hours.

A modified pectin agar medium was evaluated for the rapid isolation and presumptive identification of Yersinia enterocolitica. Of 118 isolates of Enterobacteriaceae tested, only the 13Y. enterocolitica and the three Klebsiella oxytoca strains produced colonies that depressed and sank into the agar. Yersinia enterocolitica was also easily identified in mixed cultures, even from inocula containing three times as many other Enterobacteriaceae organisms as Y. enterocolitica. The recovery of Y. enterocolitica was evaluated on Mueller-Hinton, pectin, Hektoen enteric, xylose lysine desoxycholate, Salmonella-Shigella, and MacConkey agars. Compared with Mueller-Hinton agar, the pectin agar showed a 100% recovery of Y. enterocolitica, with all strains having depressed colonies, while the other media showed lesser recoveries of only 5 to 25%, with no other discriminating colonial characteristic.

Infantile pulmonary hypertension associated with foreign body vasculitis.

An infant dying with pulmonary hypertension had a pulmonary vessel foreign body vasculitis as identified by light microscopy and characterized ultrastructurally by scanning electron microscopy and energy-dispersive x-ray analysis. The inclusions were of two distinct types: those containing silicon and titanium, and others consisting of talc. The possible sources of these inclusions and the importance of considering foreign body vasculitis in the pathogenesis of clinically idiopathic pulmonary hypertension are discussed.

Meningiomas associated with large cysts with neoplastic cells in the cysts walls. Report of two cases.

Two adults presented with frontal lobe masses. As visualized by computerized tomography, both lesions were large cysts with contrast-enhancing mural nodules and enhancing circumferential rims. En bloc resections of the mural nodules and cyst walls were performed. Pathological evaluation of each nodule disclosed a meningioma, and neoplastic cells were found in the distant cyst walls. Although the walls of large cysts associated with some meningiomas have been composed of reactive glia or collagen, the neoplastic character of the cysts in the present cases underscores the need for resection and careful pathological evaluation of the large cysts associated with meningiomas.

Elastosis in human breast cancer. Correlation with sex steroid receptors and comparison with clinical outcome.

Elastosis in human breast cancer has been compared with various prognostic indicators, but few studies have compared elastosis directly with prognosis. We examined 100 primary breast cancers for estrogen receptor (ER) and progesterone receptor (PR) content, tumor grade, and extent of elastosis and compared these data with clinical follow-up in 71 patients. The ER content was greater than 10 femtomoles (fmole) per milligram of protein in 68% of tumors, while PR content was greater than 10 fmole/mg of protein in 48%. Histologic study showed that 22% of the tumors were grade 1, 28% were grade 2, and 50% were grade 3. Grade 2 or grade 3 elastosis was seen in 36% of the tumors and grade 0 or grade 1 elastosis was seen in 64%. There was a negative correlation between tumor grade and elastosis grade and a positive correlation between ER content and elastosis grade. Elastosis grade and PR content did not correlate. A significant positive correlation existed between lymph node positivity and elastosis. No significant direct relationship between elastosis and tumor recurrence could be demonstrated once lymph node status was accounted for. Tumor elastosis correlates with histologic grade, receptor content, and lymph node involvement but does not appear to be a direct marker of prognosis.

Energy dispersive x-ray detection of thorium dioxide.

Since the recognition of the development of certain malignant neoplasms in association with thorium dioxide (Thorotrast), its presence has been documented by light microscopic appearance and time-consuming autoradiography. Energy dispersive x-ray microanalysis can be used in the rapid documentation of thorium in paraffin-embedded tissues and it is confirmed that thorium is the principal component of the granular deposits described by light microscopy.

Sensitive and specific quantification of human genomic deoxyribonucleic acid (DNA) in forensic science specimens: casework examples.

We describe the forensic science application of a method for quantification of human genomic deoxyribonucleic acid (DNA). The two cases cited in this report involve DNA samples extracted from skin tissue and bloodstained clothing recovered from different crime scenes. High-molecular-weight DNA was recovered from both specimens, and the concentrations of these DNAs were estimated to be approximately 0.5 microgram/microL by ethidium bromide/agarose gel electrophoresis. Using the human-specific DNA probe p17H8 (locus D17Z1) to quantify the amount of human genomic DNA in these samples, it is shown that less than 1% of the DNA isolated from the skin tissue is of human origin and that the DNA isolated from the bloodstained clothing is effectively devoid of human DNA sequences. These case examples illustrate the need to quantify not only the total amount of DNA recovered from forensic casework material, but also the proportion of the DNA that is of human origin.

Aflatoxicosis in swine.

In an episode of aflatoxicosis in feeder pigs, mortality was about 20%. Histopathologic findings characteristic of experimentally induced aflatoxicosis and the finding of aflatoxin B1 in the serum of pigs and in the cornbased feed confirmed the diagnosis. Aflatoxins B1 and B2 were found in the corn used to prepare the feed. Combine harvesting of the corn, which cracked a large percentage of the kernels, coupled with prolonged drying time of the corn probably contributed to the aflatoxin production. Although the corn was fed to adult swine without observable effect, 47 of the 250 feeder pigs developed typical signs of aflatoxicosis. Unseasonably cold weather apparently was a factor in initiating the onset of clinical signs and probably increased the severity of the disease.

Metabolism of [14C]diethylstilboestrol epoxide by rat liver in vitro.

1. The trans-epoxide of diethylstilboestrol and its pinacolone were synthesized chemically and the pinacolone shown to be formed from the epoxide by a non-enzymic process. 2. [14C]Diethylstiboestrol epoxide was converted by rat liver microsomal fraction into 4'-hydroxypropiophenone by a new type of cleavage reaction involving mono-oxygenase. Conditions for the formation of this metabolite and also water-soluble products were investigated together with the effect of inhibitors. A sex-difference in the conversion of diethylstilboestrol epoxide into 4'-hydroxypropiophenone and to polar and water-soluble products was observed. 3. Diethylstilboestrol epoxide was found to be a relatively stable compound that did not form a glutathione conjugate readily without further microsomal activation. A purified preparation of epoxide hydratase did not enhance its rate of conversion into the pinacolone. 4. Diethylstilboestrol epoxide was found to have about one-tenth the oestrogenic activity of diethylstilboestrol as measured by the increase in uterine weight or the induction of peroxidase in immature rat uteri. It was inactive as a mutagen when tested for its ability to inhibit bacteriophage phi X174 DNA viral replication. 5. The possible role of diethylstilboestrol epoxide as an intermediate in the metabolism of diethylstilboestrol and in mediating the harmful effects of this synthetic estrogen is discussed.

Evidence that polyoma polypeptide VP1 is a serine protease.

It has been shown that when purified polyoma (Py) virions are dissociated by incubation in 150 mM NaCl-50 mM Tris-HCl (pH 8.5) containing 1 mM EGTA and 3 mM DTT, two new polypeptides (MW 43.5K and 40K) are produced by proteolysis of virion polypeptide VP1. Proteolysis is blocked by diisopropyl fluorophosphonate (DFP) and phenylmethyl sulfonyl fluoride (PMSF), suggesting that the virion-associated enzyme is a serine protease. When Py virions were dissociated in the presence of radiolabeled DFP, only VP1 became labeled to any significant extent, which suggests that the protease activity is a property of this viral polypeptide and that the 43.5K and 40K species are produced by autodigestion.