Origin of Perpendicular Magnetic Anisotropy and Large Orbital Moment in Fe Atoms on MgO.

We report on the magnetic properties of individual Fe atoms deposited on MgO(100) thin films probed by x-ray magnetic circular dichroism and scanning tunneling spectroscopy. We show that the Fe atoms have strong perpendicular magnetic anisotropy with a zero-field splitting of 14.0±0.3 meV/atom. This is a factor of 10 larger than the interface anisotropy of epitaxial Fe layers on MgO and the largest value reported for Fe atoms adsorbed on surfaces. The interplay between the ligand field at the O adsorption sites and spin-orbit coupling is analyzed by density functional theory and multiplet calculations, providing a comprehensive model of the magnetic properties of Fe atoms in a low-symmetry bonding environment.

Fluorescence enhancement from nano-gap embedded plasmonic gratings by a novel fabrication technique with HD-DVD.

We demonstrate strong electromagnetic field enhancement from nano-gaps embedded in silver gratings for visible wavelengths. These structures fabricated using a store-bought HD-DVD worth $10 and conventional micro-contact printing techniques have shown maximum fluorescence enhancement factors of up to 118 times when compared to a glass substrate under epi-fluorescent conditions. The novel fabrication procedure provides for the development of a cost-effective and facile plasmonic substrate for low-level chemical and biological detection. Electromagnetic field simulations were also performed that reveal the strong field confinement in the nano-gap region embedded in the silver grating, which is attributed to the combined effect of localized as well as propagating surface plasmons.

Counting Single Rhodamine 6G Dye Molecules in Organosilicate Nanoparticles.

Rhodamine 6G (R6G) dye molecules have been embedded into organosilicate nanoparticles to improve thermal and chemical stability of these marker molecules. We demonstrate that the well-established method of optical single-particle microscopy can be used to determine the number of dye molecules per nanoparticle in such hybrid materials. Analysing the fluorescence intensity of R6G in single nanoparticles, we obtain an average number of 1.3 - 1.7 dye molecules per nanoparticle as compared to 1 R6G per particle obtained from ensemble experiments. The blinking behaviour of embedded R6G can be described by a power law with an exponent α(on/off) = - 1.7. Ensemble measurements complete the optical characterization of the nanoparticles, which reveals no pronounced R6G aggregate formation.

Influence of stabilizers on quality of sandesh from buffalo milk.

Buffalo milk standardized to solids-not-fat (SNF) to fat ratio of 1.4 was added separately with 0.1% (w/w) each of carrageenan, sodium alginate and carboxymethyl cellulose and then heated, cooled and coagulated to obtain chhana which was converted into sandesh by adding 1.5% (w/w) wheat flour and 25% (w/w) cane sugar followed by heating (40 min/kg chhana). The treated samples of sandesh were compared with control prepared similarly manner but without stabilizer. Addition of stabilizer decreased hardness, fracturability, adhesiveness, cohesiveness, gumminess and chewiness of sandesh and improved sensory body and texture, colour and appearance as well as overall acceptability of the product when compared with control. Textural and sensory properties of different samples of sandesh indicated that the product made by adding carrageenan proved best. Carrageenan at 0.1% produced better results in terms of textural and sensory profile of sandesh as compared to 0, 0.075 and 0.125% (w/w) of carrageenan.

Recent developments of certified reference materials for road transportation.

Chemical measurements often constitute the basis for informed decision-making at different levels in society; sound decision-making is possible only if the quality of the data used is uncompromised. To guarantee the reliability and comparability of analytical data an intricate system of quality-assurance measures has to be put into effect in a laboratory. Reference materials and, in particular, certified reference materials (CRMs) are essential for achieving traceability and comparability of measurement results between laboratories and over time. As in any other domain of analytical chemistry, techniques used to monitor the levels and fate of contaminants in the environment must be calibrated using appropriate calibration materials, and the methods must be properly validated using fit-for purpose matrix-matched CRMs, to ensure confidence in the data produced. A sufficiently large number of matrix CRMs are available for analysis of most elements, and the group of chemicals known as persistent organic pollutants, in environmental compartments and biota. The wide variety of analyte/level/matrix/matrix property combinations available from several suppliers enables analysts to select CRMs which sufficiently match the properties of the samples they analyse routinely. Certified reference materials are playing an increasing role in the monitoring of environmental pollution. This paper is an attempt for describing the recent development of certified reference materials for road transportation, which mainly covers the combustion of fossil fuel, road side dust etc.

Trends of greenhouse gas emissions from the road transport sector in India.

The road transport sector is the largest consumer of commercial fuel energy within the transportation system in India and accounts for nearly 35% of the total liquid commercial fuel consumption by all sectors. Gasoline and diesel consumption for road transportation have quadrupled between 1980 and 2000 due to about nine times increase in the number of vehicles and four-fold increase in freight and passenger travel demands. The paper elaborates the trends of energy consumption and consequent emissions of greenhouse gases such as CO(2), CH(4) and N(2)O and ozone precursor gases like CO, NO(x) and NMVOC in the road transport sector in India for the period from 1980 to 2000. For the first time, efforts have been made to apportion the fuels, both diesel and gasoline, across different categories of vehicles operating on the Indian roads. In order to generate more comprehensive and complete emission estimates, additionally, other minor fuel types like light diesel oil and fuel oil along with lubricants have also been taken into account. Emission estimates have revealed that nearly 27 Mt of CO(2) were emitted in 1980, increasing to about 105 Mt in 2000. Similar trends have also been observed for other gases. Further scope for improvements in emission estimation is possible by generating country specific emission factors for different vehicle categories and improvement in documentation of fuel consumption at segregated levels by fuel types and vehicle types.

Molecular and functional analysis of the muscle-specific promoter region of the Duchenne muscular dystrophy gene.

Duchenne muscular dystrophy (DMD) gene transcripts are most abundant in normal skeletal and cardiac muscle and accumulate as normal myoblasts differentiate into multinucleated myotubes. In this report we describe our initial studies aimed at defining the cis-acting sequences and trans-acting factors involved in the myogenic regulation of DMD gene transcription. A cosmid clone containing the first exon of the DMD gene has been isolated, and sequences lying upstream of exon 1 were analyzed for homologies to other muscle-specific gene promoters and for their ability to direct muscle-specific transcription of chimeric chloramphenicol acetyltransferase (CAT) gene constructs. The results indicate that the transcriptional start site for this gene lies 37 base pairs (bp) upstream of the 5' end of the published cDNA sequence and that 850 bp of upstream sequence can direct CAT gene expression in a muscle-specific manner. Sequence analysis indicates that in addition to an ATA and GC box, this region contains domains that have been implicated in the regulation of other muscle-specific genes: a CArG box at -91 bp; myocyte-specific enhancer-binding nuclear factor 1 binding site homologies at -58, -535, and -583 bp; and a muscle-CAAT consensus sequence at -394 bp relative to the cap site. Our observation that only 149 bp of upstream sequence is required for muscle-specific expression of a chimeric CAT gene construct further implicates the CArG and myocyte-specific enhancer-binding nuclear factor 1 binding homologies as important domains in the regulation of this gene. On the other hand, the unique profile of myogenic cell line-specific induction displayed by our DMD promoter-CAT gene constructs suggests that other as yet undefined cis-acting sequences and/or trans-acting factors may also be involved.

Transcriptional activation by ETS and leucine zipper-containing basic helix-loop-helix proteins.

The immunoglobulin mu heavy-chain gene enhancer contains closely juxtaposed binding sites for ETS and leucine zipper-containing basic helix-loop-helix (bHLH-zip) proteins. To understand the mu enhancer function, we have investigated transcription activation by the combination of ETS and bHLH-zip proteins. The bHLH-zip protein TFE3, but not USF, cooperated with the ETS domain proteins PU.1 and Ets-1 to activate a tripartite domain of this enhancer. Deletion mutants were used to identify the domains of the proteins involved. Both TFE3 and USF enhanced Ets-1 DNA binding in vitro by relieving the influence of an autoinhibitory domain in Ets-1 by direct protein-protein associations. Several regions of Ets-1 were found to be necessary, whereas the bHLH-zip domain was sufficient for this effect. Our studies define novel interactions between ETS and bHLH-zip proteins that may regulate combinatorial transcription activation by these protein families.

Dorsal plating of unstable distal radius fractures using a bio-absorbable plating system and bone substitute.

This study reports the results of open reduction and internal fixation of 26 unstable, intraarticular, dorsally displaced fractures of the distal radius using a bio-absorbable dorsal distal radius (Reunite) plate and calcium phosphate (Biobon) bone substitute. The bio-absorbable plate has the advantage of being low profile, easily contourable and angularly stable. In the majority of cases, this plate produces functional results comparable with metal plates. The Gartland and Werley score was excellent or good in 21 patients. The theoretical advantage over metal plates is in eliminating the need to remove the plate and hence the need for a second operation if implant-related extensor tenosynovitis occurs. Inflammatory tissue reaction to the degradation products of the plate is a potential concern, although the co-polymer ratio used in this plate appears to have reduced the severity of this reaction, which was seen in two patients in this series. The reduction was lost in five patients with severe dorsal comminution. Following this experience, we do not recommend this plating system for fractures with a metaphyseal gap of greater than 7 mm following reduction.

Plasmonic gratings with nano-protrusions made by glancing angle deposition for single-molecule super-resolution imaging.

Super-resolution imaging has been advantageous in studying biological and chemical systems, but the required equipment and platforms are expensive and unable to observe single-molecules at the high (µM) fluorophore concentrations required to study protein interaction and enzymatic activity. Here, a plasmonic platform was designed that utilized an inexpensively fabricated plasmonic grating in combination with a scalable glancing angle deposition (GLAD) technique using physical vapor deposition. The GLAD creates an abundance of plasmonic nano-protrusion probes that combine the surface plasmon resonance (SPR) from the periodic gratings with the localized SPR of these nano-protrusions. The resulting platform enables simultaneous imaging of a large area without point-by-point scanning or bulk averaging for the detection of single Cyanine-5 molecules in dye concentrations ranging from 50 pM to 10 µM using epifluorescence microscopy. Combining the near-field plasmonic nano-protrusion probes and super-resolution technique using localization microscopy, we demonstrate the ability to resolve grain sizes down to 65 nm. This plasmonic GLAD grating is a cost-effective super-resolution imaging substrate with potential applications in high-speed biomedical imaging over a wide range of fluorescent concentrations.

A transcript exhibiting homology to endogenous rat retroviral-like elements is regulated by p53.

Rat embryo fibroblasts transformed with HPV-16 E7 and the Ha-ras oncogene (ER clones) fall into two distinct groups based on their endogenous p53 status, wild-type or mutant. We have taken advantage of such clones in order to study the p53 target genes by the differential display method of RNA fingerprinting. We have identified a cDNA clone, clone 16, that recognises a large transcript on Northern blots. The clone 16 transcript is overexpressed in ER cell lines that express wild-type p53 compared with ER cell lines that express mutant p53. Similar to the waf1/p21 gene, which is transcriptionally activated in cells treated with ionizing radiation in a p53-dependent manner, the clone 16 transcript was also induced in response to cell irradiation. The sequence of clone 16 exhibits a high homology to two members of RAL retroviral-like elements.

Unusual genome organisation in Entamoeba histolytica leads to two overlapping transcripts.

We have isolated homologs of the mini chromosome maintenance (MCM) gene family from the parasitic protozoan Entamoeba histolytica. The full length genomic and cDNA clones for the Eh MCM3 gene have been characterised. The Eh MCM3 gene is much smaller than the Saccharomyces cerevisiae MCM3 gene and other eukaryotic homologs of the MCM3/P1 family. The predicted Eh Mcm3 protein was 597 amino acids long and showed 37 and 46% positional identity with the Sc Mcm3 and the mouse P1 homologs respectively. While proceeding along the chromosome from the Eh MCM3 gene, we have identified a homolog (Eh PAK) of the murine p21 activated kinase (Rn KPAK), or S. cerevisiae STE20. Eh PAK lies 126 bp upstream of the Eh MCM3 gene. The predicted Eh p21 activated kinase protein was 459 amino-acids long and showed 33% positional identity with the murine p21 activated kinase and its yeast homolog Ste20. Analysis of cDNA and genomic sequences shows that the 3' untranslated region (UTR) of the Eh PAK mRNA and the 5' UTR of the Eh MCM3 mRNA are transcribed from a common 40 bp genomic segment. This is the first report of an amoeba gene being physically linked to a second gene such that their transcripts are overlapping and there is no non-transcribed intergenic region between the two genes. Primer extension studies have confirmed that unlike most E. histolytica genes, which have short 5' UTRs, the Eh MCM3 mRNA has a 126 bp long 5' UTR and the Eh PAK mRNA has a 265 bp long 5' UTR.

Heterogeneity of DNA content and expression of cell cycle genes in axenically growing Entamoeba histolytica HM1:IMSS clone A.

The cell division cycle of Entamoeba histolytica was studied using multi-parametric flow cytometry in asynchronous and partially synchronised cells. Dynamic changes in the DNA synthesis and DNA content of axenically growing trophozoites were observed by using 5-bromo-2'-deoxyuridine (BrdU) uptake and DNA specific fluorochromes. It was observed that DNA synthesis in these cells continues beyond the typical S-phase stop point when DNA duplication is complete. Asynchronously growing E. histolytica cells could be synchronised by serum starvation followed by serum re-addition. BrdU incorporation in synchronised cells showed that cell synchrony is maintained for at least one generation time, in which the G1 phase lasts for 2-3 h and the S-phase lasts for 5-6 h. Analysis of our results revealed that E. histolytica trophozoites, growing in axenic medium, are made up of a heterogenous population of euploid and polyploid cells. The number of polyploid cells increases with age of the cells in culture. Expression of putative cell cycle and signal transduction markers was studied using specific antibodies and changes in their expression levels have been correlated with changes in the DNA content. Based upon our results we could identify G1, S and G2 phases of the cell cycle of E. histolytica and also predict the mechanism underlying the generation of polyploidy in these cells, which may have significant effects on its biology and pathogenesis.

Optical waveguides with an aqueous core and a low-index nanoporous cladding.

We report measurements on planar optical waveguides having an aqueous core and a low-index nanoporous dielectric cladding. Spin-on deposition of the nanoporous dielectric results in a thin (~0.8 microm) low-index cladding layer on a higher-index fused silica substrate, which produces leaky waveguide modes; however, for the aqueous layer thickness needed in most microfluidic applications, a large number of low-loss modes exist. We demonstrate that such a waveguide can be used for efficient collection and transport of fluorescence generated within the aqueous core and show that the use of these nanoporous materials offers advantages over the principal alternative, Teflon(R) AF.

Invited review: cross-bridge regulation by thin filament-associated proteins.

This minireview will cover current concepts on the identity and mechanistic function of smooth muscle actin binding proteins that may regulate actin-myosin interactions. The potential roles of tropomyosin, caldesmon, calponin, and SM22 will be discussed. The review, for purposes of brevity, will be nonexhaustive but will give an overview of available information on the in vitro biochemistry and potential in vivo function of these proteins. Preterm labor is discussed as a possible example of where thin filament regulation may be relevant. Considerable controversy surrounds the putative physiological significance of these proteins, and emphasis will be placed on the need for more experimental work to determine the degree to which tissue- and species-specific effects have clouded the interpretation of functional data.

Overcoming cisplatin resistance: design of novel hydrophobic platinum compounds.

BACKGROUND: The anticancer activity of cisplatin derives from its ability to crosslink DNA. Cisplatin-resistance is partially caused by enhanced nucleotide excision repair (NER). Major 1,2-intrastrand crosslinks can create a hydrophobic notch at the damage site, which can be specifically bound by damage-recognition proteins, thus shielded from NER-activity. We aimed at preventing resistance by enhancing this mechanism using more hydrophobic platinum compounds. METHODS: We synthesized three platinum analogs with increased hydrophobic characteristics. Performing MTT-assays, the efficacy of cisplatin and the novel agents was compared in a fibroblast and eight brain tumour cell lines. RESULTS: Among the novel compounds, the most hydrophobic molecule, methylpyridineplatinum, was most cytotoxic (LC50 = 5.84 x 10(-5) M), followed by methylpyrazineplatinum, the second most hydrophobic (LC50 = 1.79 x 10(-4) M), and pyridineplatinum (LC50 = 2.76 x 10(-4) M). Overall, cisplatin revealed highest cytotoxicity (LC50 = 8.77 x 10(-6) M). CONCLUSIONS: Comparison of the novel compounds supports the hypothesis that increased hydrophobicity contributes to higher antitumour-activity. Other advantageous characteristics of cisplatin might relate to its remaining highest efficacy.

Cellular accumulation determines the activity of three novel tricyclic platinum agents.

BACKGROUND: Cisplatin (CDDP) is a very useful chemotherapeutic agent, but cellular resistance limits its efficacy in malignant glioma. In order to analyze and overcome this resistance, we synthesized three novel platinum compounds; aminoplatin, methylplatin and oxiplatin, using tricyclic DNA intercalating molecules as models. MATERIALS AND METHODS: The novel compounds differ only in one chemical group, which is positioned opposite to the DNA binding site. DNA binding, cellular penetration, and cytotoxicity were compared in three human glioma cell lines (T98G, U87-MG, and U25 IN) and a human fibroblast cell strain (HS 68). 2 RESULT: Binding to isolated DNA was most effective in aminoplatin, followed by methylplatin and oxiplatin. It differed by factors I. I, 0.35, 0.23, from the DNA binding of CDDP (factor I) for the three compounds, respectively. The cellular penetration, however, was fastest with oxiplatin (factor 10.1) followed by CDDP (1), aminoplatin (0.55), and methylplatin (0.27). The cytotoxicity of the three novel compounds followed the pattern of their cellular penetration with oxiplatin being the most active. U87-MG cells were resistant to CDDP, and in this cell line oxiplatin was more effective than CDDP in overcoming the resistance. CONCLUSION: This indicates cellular penetration to be an important feature and the ketogroup of oxiplatin to be beneficial in tricyclic platinum compounds.

Echocardiographic assessment of patients receiving long-term treatment with anorexiant medications.

OBJECTIVE: To describe the prevalence and evaluate the risk of echocardiogram-determined valvulopathy in patients who received fenfluramine and phentermine in an effort to lose weight, in comparison with normal control subjects. METHODS: A historical cohort study was conducted in a clinical obesity-management practice. A total of 164 patients (88% women) who were treated with fenfluramine-phentermine for weight loss had echocardiographic evaluations. A subsample was cross-validated. RESULTS: The prevalence of mild or greater aortic regurgitation was 18.3%, and the prevalence of moderate or greater mitral regurgitation was 3.7%. The prevalences of mild or greater tricuspid and pulmonary valve regurgitation, valve thickening, and pulmonary hypertension were 23.2%, 5.5%, 10.4%, and 6.7%, respectively. No significant increases in risk were found for moderate or greater regurgitation of any valve. Patients had at least a 3-fold risk for mild or greater aortic regurgitation (standardized morbidity ratio [SMR] = 3.03; 95% confidence interval [CI] = 2.05 to 4.33) and a 2-fold risk for tricuspid regurgitation (SMR = 2.24; 95% CI = 1.58 to 3.06) in comparison with normal healthy adults. Age and duration of drug therapy predicted increased risk for aortic regurgitation. Four patients who had moderate or greater aortic regurgitation had taken the fenfluramine-phentermine combination continuously for 454, 615, 645, and 984 days. CONCLUSION: Use of serotonergic anorexiant medications may increase risk for mild or greater aortic and tricuspid regurgitation, although selection bias and obesity as causes of the association cannot be ruled out. Age and duration of drug therapy were predictors of aortic valvulopathy. Population-based studies are needed to confirm these preliminary findings.

Extraction and spectrophotometric determination of ruthenium and osmium with thiobenzhydrazide.

Ruthenium forms a pink complex with thiobenzhydrazide in hot 1.0-4.5M hydrochloric acid medium, which can be extracted with chloroform, and the extract shows maximal absorbance at 520 nm. The chloroform-extractable osmium-thiobenzhydrazide complex formed at pH 2.3-4.8 shows maximal absorption at 385 nm as well as at 480-490 nm. The colour of the extracts of both the complexes is stable for more than 24 hr and can be employed for the spectrophotometry of ruthenium and osmium in the presence of a considerable excess of diverse ions commonly associated with them. Ruthenium and osmium can be quantitatively separated from one another with thiobenzhydrazide.

A comparative study between longitudinal and "T" incisions for dorsal plating of the distal radius.

A retrospective review of 24 patients with dorsal incisions for open reduction and internal fixation of Frykman VII/VIII distal radius fractures using a dorsal plate was performed. Half of them had a longitudinal incision while the other half had a T-shaped incision. No difference in the healing properties or wound morbidity could be demonstrated between the two groups. However, the T incision provided improved exposure of the distal radius and patient satisfaction with its cosmetic result was superior. The horizontal limb was well camouflaged within the transverse skin crease on the dorsal aspect of the wrist. The vertical limb did not extend into the dorsum of the hand and could, therefore, be hidden by appropriate clothing.