Preparation of avidin-containing polyelectrolyte microcapsules and their uptake and release properties

Avidin-containing polyelectrolyte microcapsules were prepared by a layer-by-layer deposition technique and uptake and release of biotin-labelled fluorescein (b-FITC) was studied. The polyelectrolyte microcapsules were prepared by coating the surface of calcium carbonate (CaCO₃) microparticles containing avidin-poly(styrene sulfonate) (PSS) conjugate, followed by dissolution of CaCO₃ core in an ethylenediaminetetraacetic acid solution. Release of avidin from the microcapsules was markedly suppressed due to formation of a high molecular weight of avidin-PSS conjugate in the microcapsules. The uptake of b-FITC into the microcapsules was highly enhanced through a strong binding of b-FITC to avidin, as compared to the uptake into avidin-free microcapsules. Release of b-FITC from the microcapsules was accelerated upon addition of biotin, 2-iminobiotin, or lipoic acid in the solution due to the competitive binding of the additives to the binding site of avidin.     

Magnetic and EPR studies of edge-localized spin paramagnetism in multi-shell nanographites derived from nanodiamonds

Prolonged (up to 2 h) heat treatment at 1600 °C of nanodiamond particles (5 nm) leads to their conversion to the mixture of quasi-spherical carbon onions and multi-shell polyhedral nanographites. Structural and magnetic properties of two (A and B) series of nanographite samples obtained at various annealing intervals were studied. XRD data show that both multi-shell nanographite samples have practically the same crystalline structures. HRTEM evidences that the most of particles obtained by short time (7 min) annealing have a spherical like shape whereas the long time (~ 2 h) annealing leads to the majority of particles having a polyhedral shape with a hollow inside. Electronic and magnetic properties of these nanocarbons were investigated by magnetic susceptibility and EPR. Annealing results in entire transformation of the EPR signal of nanodiamond to new EPR signals of various line shapes and widths. These signals are extremely sensitive to ambient oxygen. Concentrations for all EPR active spins vary from ~ 1 × 10¹⁹ spins/g (7 min) to ~ 2 × 10¹⁹ spins/g (2 h). Temperature dependences of EPR spectra' parameters were obtained for vacuum-processed samples within the range 4?600 K. Intensity vs. T plots may be well-fitted by the combination of Curie–Weiss and temperature-independent Pauli susceptibility contributions. The latter one increases on heat treatment. Significant extension of electron spin-lattice relaxation time on decreasing temperature was found.     

Mercury and selenium concentrations in the internal organs of toothed whales and dolphins marketed for human consumption in Japan

Small cetaceans (toothed whales odontoceti and dolphins delphinidae) have been traditionally hunted along the coast of Japan and fresh red meat and blubber, as well as boiled internal organs such as liver, kidney, lung and small intestine, are still being sold for human consumption. We surveyed mercury contamination in boiled liver, kidney and lung products marketed in Japan between 1999-2001. The average +/- S.D. of total mercury (T-Hg) was 370 +/- 525 (range: 7.60 approximately 1980, n = 26) microg/g in liver, 40.5 +/- 48.5 (7.30-95.1, n = 15) microg/g in kidney and 42.8 +/- 43.8 (2.10-79.6, n = 23) microg/g in lung. A high correlation was observed between T-Hg and selenium (Se) concentrations in these organs, supporting the formation of a Hg-Se complex. The formation of a Hg-Se complex probably contribute to the detoxification of Hg for cetaceans and allows a very large accumulation of Hg in livers. The provisional permitted level of T-Hg in marine foods set by the Japanese Ministry of Health and Welfare is 0.4 microg/ g, and the provisional permitted weekly intake (PTWI) set by WHO is 5 microg/kg bw/week. The maximal T-Hg detected in boiled liver (1,980 microg/g) exceeds the permitted level by approximately 5,000 times and the consumption of only 0.15 g of liver exceeds the PTWI of 60 kg of body weight of the consumer, suggesting the possibility of an acute intoxication by T-Hg even after a single consumption of the product.     

Microsequencing of glycans using 2-aminobenzamide and MALDI-TOF mass spectrometry: occurrence of unique linkage-dependent fragmentation

2-Aminobenzamide-derivatized oligosaccharides were separated by three lectin column chromatographies and then subjected to matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) for structural characterization of the carbohydrates. The combination of sequential exoglycosidase digestion and MALDI-TOF MS greatly facilitates the monosaccharide sequencing and is more feasible than size-exclusion column chromatography in terms of the time consumed and the laboriousness of the procedure. By this strategy, microsequencing of 2-3 pmol of oligosaccharide derivatives could be achieved. Furthermore, spectra obtained by the post source decay (PSD) mode provide excellent sequence information. The relative intensities of metastable ions due to fragmentation at glycosidic linkages were different among linkage isomers of particular oligosaccharides. These results demonstrate that PSD analysis possesses significant potential for the estimation of glycosidic linkage in carbohydrate structures.     

Improvement of productivity of active horseradish peroxidase in Escherichia coli by coexpression of Dsb proteins

Coexpression of two classes of folding accessory proteins, molecular chaperones and foldases, can be expected to improve the productivity of soluble and active recombinant proteins. In this study, horseradish peroxidase (HRP), which has four disulfide bonds, was selected as a model enzyme and overexpressed in Escherichia coli. The effects of coexpression of a series of folding accessory proteins (DnaK, DnaJ, GrpE, GroEL/ES, trigger factor (TF), DsbA, DsbB, DsbC, DsbD, and thioredoxin (Trx)) on the productivity of active HRP in E. coli were examined. Active HRP was produced by very mild induction with 1 microM isopropyl-beta-D-thiogalactopyranoside (IPTG) at 37 degrees C, whereas the amount of active HRP produced by the induction with 1 mM IPTG was negligibly small. Active HRP production was increased significantly by coexpression of DsbA-DsbB (DsbAB) or DsbC-DsbD (DsbCD), while coexpression of molecular chaperones did not improve active HRP production. The growth of E. coli cells was inhibited significantly by the induction with 1 mM IPTG in a HRP single expression system. In contrast, when HRP was coexpressed with DsbCD, the growth inhibition of E. coli was not observed. Therefore, coexpression of Dsb proteins improves both the cell growth and the productivity of HRP.     

STORY GENERATION BASED ON DYNAMICS OF THE MIND

A story generation system based on dynamics of the mind is presented. Semantic theories until now avoided discussing a linkage of language with encyclopedic human knowledge. This paper attacks the problem of how to make clear the complicated, wide-ranging dynamics of the mind and how to connect it to language.
First, the background of this study is shown, in which our model of the mind, with both five levels along the concept formation process and eight domains according to the contents of mental activities, is surveyed.
Based on this model, then, the dynamics of mind are discussed, along an Aesop fable. A unit of data processing in the mind is called a "module," and the mental dynamics are considered as a chain activation of those modules, represented by a dynamic network. Next, a method for story generation is discussed. Propositional information of a sentence is embedded in a slot of activated, frame-structured modules, and the discourse structure of a generated story basically depends on the dynamic network. Both the chain activation and the generation processes are verified by experiments.
Lastly, residual problems of our research, a comparison with related research, and its applications are discussed.
This case study would be expected to give a basis to integrated systems for problem solving, natural language and image understandings, their generations, and intelligent robots.     

Characterization of the radical trapping activity of a novel series of cyclic nitrone spin traps

alpha-Phenyl-tert-butyl nitrone (PBN) is a nitrone spin trap, which has shown efficacy in animal models of oxidative stress, including stroke, aging, sepsis, and myocardial ischemia/reperfusion injury. We have prepared a series of novel cyclic variants of PBN and evaluated them for radical trapping activity in vitro. Specifically, their ability to inhibit iron-induced lipid peroxidation in liposomes was assessed, as well as superoxide anion (O2(-.)) and hydroxyl radical ((.)OH) trapping activity as determined biochemically and using electron spin resonance (ESR) spectroscopy. All cyclic nitrones tested were much more potent as inhibitors of lipid peroxidation than was PBN. The unsubstituted cyclic variant MDL 101,002 was approximately 8-fold more potent than PBN. An analysis of the analogs of MDL 101,002 revealed a direct correlation of activity with lipophilicity. However, lipophilicity does not solely account for the difference between MDL 101,002 and PBN, inasmuch as the calculated octanol/water partition coefficient for MDL 101,002 is 1.01 as compared to 1.23 for PBN. This indicated the cyclic nitrones are inherently more effective radical traps than PBN in a membrane system. The most active compound was a dichloro analog in the seven-membered ring series (MDL 104,342), which had an IC50 of 26 mum, which was 550-fold better than that of PBN. The cyclic nitrones were shown to trap (.)OH with MDL 101,002 being 20 25 times more active than PBN as assessed using 2-deoxyribose and p-nitrosodimethylaniline as substrates, respectively. Trapping of (.)OH by MDL 101,002 was also examined by using ESR spectroscopy. When Fenton's reagent was used, the (.)OH adduct of MDL 101,002 yielded a six-line spectrum with hyperfine coupling constants distinct from that of PBN. Importantly, the half-life of the adduct was nearly 5 min, while that of PBN is less than 1 min at physiologic pH. MDL 101,002 also trapped the O2(-.) radical to yield a six-line spectrum with coupling constants very distinct from that of the (.)OH adduct. In mice, the cyclic nitrones ameliorated the damaging effects of oxidative stress induced by ferrous iron injection into brain tissue. Similar protection was not afforded by the lipid peroxidation inhibitor U74006F, thus implicating radical trapping as a unique feature in the prevention of cell injury. Together, the in vivo activity, the stability of the nitroxide adducts, and the ability to distinguish between trapping of (.)OH and O2(-.) suggest the cyclic nitrones to be ideal reagents for the study of oxidative cell injury.     

Postoperative complications after coronary bypass operations in patients with pulmonary impairment]

Two women with atrial escape-capture bigeminy were reported in whom sinus P waves and escape P waves alternated with each other. Their electrocardiographic findings showed that, during the bigeminal rhythm, 2:1 exit block of sinus impulses associated with entrance block of escape impulses occurred in the sinoatrial junction. Three phenomena are suggested to explain the observations. (1) Seeming bradycardia-dependent sinoatrial exit block may have occurred, probably as a result of phasic changes in vagal tone due to respiration, with decreased vagal tone depressing conductivity in the sinoatrial junction to a greater degree than automaticity in the sinus node. (2) In case 1, type II second-degree entrance block in the sinoatrial junction may have occurred, reflecting the presence of sinus parasystole with incomplete entrance block. (3) Sinus escape also may have occurred, especially in case 2. These phenomena have never been reported before.     

Absence of normal activation of the left anterior fusiform gyrus during naming in left temporal lobe epilepsy

Patients with left temporal lobe epilepsy (TLE) often have impaired naming. We studied 13 patients with left TLE and 10 healthy control subjects with [(15)O]H2O PET during visual confrontation naming. Statistical mapping detected multiple regions of significant cerebral blood flow increases within individuals. The left fusiform gyrus was activated in nine healthy subjects, but only in two patients with TLE (a significant difference, p < 0.001). Other activation sites were more variable in healthy subjects and those with TLE. Impaired naming ability may be associated with a lack of increased cerebral blood flow in the left fusiform gyrus in TLE.     

Children of affectively ill parents: a review of the past 10 years

OBJECTIVE: To review the literature investigating the effects of parental affective illness on children over the past decade. METHOD: A computerized search of articles published over the past 10 years was completed. Articles were reviewed and relevant studies are presented. RESULTS: Over the course of the past 10 years a number of longitudinal studies have confirmed that children of affectively ill parents are at a greater risk for psychiatric disorders than children from homes with non-ill parents. Life table estimates indicate that by the age of 20 a child with an affectively ill parent has a 40% chance of experiencing an episode of major depression. Children from homes with affectively ill parents are more likely to exhibit general difficulties in functioning, increased guilt, and interpersonal difficulties as well as problems with attachment. Marital difficulties, parenting problems, and chronicity and severity of parental affective illness have been associated with the increased rates of disorder observed in these children. CONCLUSION: The presence of depression in parents should alert clinicians to the fact that their children also may be depressed and therefore in need of services. J. Am. Acad. Child Adolesc.