X-ray phase contrast imaging of spherical capsules

We demonstrate that a laser-based synchrotron X-ray source can be used to image and characterize in a single laser shot spherical capsules similar to ICF targets. Thus, we establish this source potential for real-time ultrafast imaging of the ICF laser driver interaction with the target. To produce the X-ray beam we used a 160 TW high power laser system with 3.2 J and 20 fs incident on a supersonic gas jet target at 2.5 Hz repetition rate. We produced 2.7 × 10⁹ photons/0.1% BW/sr/shot at 10 keV with a critical energy E_c = 15.1 keV. In our experimental conditions the spatial resolution was 4.3 μm in the object plane. We show that it is feasible to image the capsule structure and experimentally retrieve the phase information.

The impact of chronic hepatitis C infection on cholesterol metabolism in PBMCs is associated with microRNA-146a expression

Chronic hepatitis C (CHC) infection is known to induce important changes in host cholesterol metabolism. MicroRNAs (miRNAs) regulate the expression of many genes and, in consequence, control various processes, including human metabolism and response to viral infection. Recently, the alteration of the immune-associated miR-146a, which is abundantly present in peripheral blood mononuclear cells (PBMCs), was found in some viral infections. The study aimed to analyse the influence of hepatitis C virus (HCV) infection on miR-146a expression in PBMCs in vivo and in vitro, as well as to assess the possible impact of miR-146a alteration on the intracellular cholesterol level in PBMCs. Blood samples collected from 42 healthy donors and 72 CHC patients were the source of materials. HCV RNA, intracellular cholesterol level and miR-146a expression were determined in PBMCs, as well as HCV genotype and interferon (IFN)α concentration in sera. The influence of miR-146a inhibition on cholesterol expression in PBMCs was analysed in vitro after transient cell transfections with mirVana™ anti-miR-146a Inhibitor. Our data demonstrated an alteration of miR-146a and intracellular cholesterol expression in PBMCs and of IFNα concentration in sera of genotype 1, HCV-infected patients compared to the healthy donors. Also, in cultured PBMCs, miR-146a expression and intracellular cholesterol level were significantly decreased in CHC patients compared to the healthy donors. In vitro blockage of miR-146a expression in PBMCs of CHC patients greatly impaired intracellular cholesterol expression. In these conditions, miR-146a expression was positively correlated with the intracellular cholesterol level. These results suggest that genotype 1 HCV infection may alter miR-146a expression in PBMCs and, consequently, contribute to the observed dysregulation of cholesterol synthesis.

Randomized Placebo-Controlled Trial of Metronidazole 1 % Cream with Sunscreen SPF 15 in Treatment of Rosacea

Background:

Rosacea is a photoaggravated dermatosis responsive to treatment with topical and oral antibiotics. A formulation combining metronidazole 1% cream with sunscreen SPF 15 was developed for the treatment of rosacea. Objective: The objective of this study was to determine the safety and efficacy of a formulation combining metronidazole 1% cream with sunscreen SPF 15 in the treatment of moderate to severe rosacea.

Methods:

One hundred and twenty patients with moderate to severe rosacea were enrolled for a randomized, placebo-controlled (vehicle containing sunscreen with SPF 15), double-blind study. Study cream was applied twice daily to the entire face over a 12-week period.

Results:

Treatment with metronidazole 1% cream with sunscreen SPF 15 resulted in significant improvement ( p < 0.05) in inflammatory lesion count, erythema and telangiectasiae scores, and investigator and patient global assessment scores compared with baseline and placebo. Adverse reactions related to study medication were typically mild, occurred at the site of application, and were reversible. There was no difference between the safety profiles of metronidazole 1% cream with sunscreen SPF 15 and placebo.

Conclusions:

The combined topical formulation of metronidazole 1% cream with sunscreen SPF 15 was an effective, well-tolerated topical agent for the treatment of moderate to severe rosacea.

Acute Generalized Exanthematous Pustulosis Induced by Oral Fluconazole

Background:

Acute generalized exanthematous pustulosis (AGEP) is a generalized, nonfollicular, pustular eruption of the skin associated with fever and leukocytosis. The cause of AGEP has mainly been attributed to drugs.

Objective:

We report a unique case of AGEP in a 75-year-old male caused by oral fluconazole. We include clinical as well as histological illustrations of our case.

Conclusion:

Based on a current literature search using the MEDLINE electronic database, this is the first reported case of AGEP arising from use of oral fluconazole. The clinical presentation, clinical course, and histology are consistent with prior reports of AGEP resulting from other drugs. AGEP should be considered a possible complication of oral fluconazole treatment.

Interactions between smoking, increased serum levels of anti-CCP antibodies, rheumatoid factors, and erosive joint disease in patients with early, untreated rheumatoid arthritis

OBJECTIVES

To determine to what extent shared epitopes, smoking, and anti-cyclic citrullinated peptide (anti-CCP) antibodies are associated with disease activity and erosive disease in patients with rheumatoid arthritis (RA) at disease onset.

METHOD

RA patients not previously treated with disease-modifying anti-rheumatic drugs (DMARDs) and with a disease duration of < 6 months (CIMESTRA study) were examined for shared epitopes, anti-CCP antibodies, immunoglobulin M rheumatoid factor (IgM-RF) and IgA-RF, radiographic erosive changes in hands and feet, and clinical disease activity.

RESULTS

The study comprised 153 patients, of whom 104 (68%) were ever-smokers. The prevalence of patients with 0, 1, or 2 shared epitopes was 40 (48%), 71 (49%), and 33 (23%), respectively. Anti-CCP antibodies, IgM-RF, and IgA-RF were present in 89 (58%), 99 (65%), and 82 (54%) patients, respectively. Among smokers, erosive disease was associated with anti-CCP antibodies [odds ratio (OR) 3.9, 95% confidence interval (CI) 1.6-9.3], IgM-RF (OR 4.9, 95% CI 1.9-12), and IgA-RF (OR 2.8, 95% CI 1.2-6.4) but absent with regard to shared epitopes. Among never-smokers, erosive disease was not associated with either shared epitopes or antibodies. All antibody levels measured were associated with smoking and shared epitopes.

CONCLUSIONS

Shared epitopes and smoking were associated with the production of anti-CCP antibodies and rheumatoid factors of IgM and IgA isotypes, which again were associated with erosive disease at presentation only in smokers. As shared epitopes and smoking were not directly associated with erosive disease, smoking may enhance the development of erosive disease in RA at different levels or through separate pathways.

X Chromosome-Inactivation Patterns in 31 Individuals with PHACE Syndrome

Segmental hemangiomas of the head and neck can be associated with multiple congenital anomalies in the disorder known as PHACE syndrome (OMIM 606519) (posterior fossa malformations, hemangioma, arterial anomalies, cardiac defects, and eye anomalies). All reported cases of PHACE syndrome to date have been sporadic, and the genetic basis of this disorder has not yet been established. PHACE syndrome has a striking female predominance which has raised the question of X-linked inheritance. In this study, the X chromosome-inactivation (XCI) patterns of 31 females with PHACE syndrome and their mothers were analyzed using blood-derived DNA and X-chromosome locus methylation assay. This study was performed to test the hypothesis that some cases of PHACE syndrome are due to X-linked inheritance and favorable skewing in the mothers may protect against a severe phenotype, but the clinical phenotype may be unmasked in daughters with a random pattern of X-inactivation. XCI analysis was informative in 27/31 mothers. Our results identified skewed XCI in 5 of 27 (19%) informative mothers, which is not statistically significant with a p value of 0.41. None of the mothers reported significant medical problems, although a full PHACE work-up has not been performed in these individuals. Skewed XCI in the mothers of children with PHACE was identified in only a minority of cases. Based on these results, genetic heterogeneity is likely in PHACE syndrome, although it is possible a subset of cases are caused by a mutation in an X-linked gene.

Evaluation of novel genetic algorithm generated schemes for positron emission tomography (PET)/magnetic resonance imaging (MRI) image fusion

The use and benefits of a multimodality approach in the context of breast cancer imaging are discussed. Fusion techniques that allow multiple images to be viewed simultaneously are discussed. Many of these fusion techniques rely on the use of color tables. A genetic algorithm that generates color tables that have desired properties such as satisfying the order principle, the rows, and columns principle, have perceivable uniformity and have maximum contrast is introduced. The generated 2D color tables can be used for displaying fused datasets. The advantage the proposed method has over other techniques is the ability to consider a much larger set of possible color tables, ensuring that the best one is found. We asked radiologists to perform a set of tasks reading fused PET/MRI breast images obtained using eight different fusion techniques. This preliminary study clearly demonstrates the need and benefit of a joint display by estimating the inaccuracies incurred when using a side-by-side display. The study suggests that the color tables generated by the genetic algorithm are good choices for fusing MR and PET images. It is interesting to note that popular techniques such as the Fire/Gray and techniques based on the HSV color space, which are prevalent in the literature and clinical practice, appear to give poorer performance.

Studies of an InAs/GaAs Heterojunction by Total-Electron-Yield

Total electron yield (TEY) of an InAs/GaAs heterojunction due to soft x-ray excitation has been studied. This heterojunction was prepared by an overgrowth of a 600 Å InAs layer on a GaAs substrate using molecular beam epitaxy. Experimental data are compared with theoretical analysis based on a modified Fresnel formulation to calculate the wave field distribution in stratified media with interfacial roughness. The TEY angular profiles obtained at a given x-ray energy reveal information on the interfacial roughness, secondary electron escape length, attenuation length of elastically scattered photo-electrons, and optical constants of the epilayer in the xray regime.

Determinants of late HIV diagnosis among different transmission groups in Finland from 1985 to 2005

OBJECTIVES

To study determinants of late HIV diagnosis in a low-HIV-prevalence (<0.1%) country where HIV spread among men who have sex with men (MSM) and heterosexuals in the 1980s, and among injecting drug users (IDUs) in the late 1990s.

METHODS

Newly diagnosed HIV cases referred to the Helsinki University Central Hospital between 1985 and 2005 were reviewed to identify determinants of late HIV diagnosis, defined as diagnosis when the first CD4 count was <200 cells/microL, or when AIDS occurred within 3 months of HIV diagnosis. Determinants of late diagnosis were analysed using multivariate logistic regression.

RESULTS

Among 934 HIV cases, 211 (23%) were diagnosed late. In the first 4-year interval of each sub-epidemic (1985-1989 for MSM and heterosexuals, 1998-2001 for IDUs), rates of late HIV diagnosis were 13%, 18% and 6%, respectively, but increased thereafter to 29%, 27% and 37%. Late diagnosis was associated with non-Finnish ethnicity, older age, male gender, lack of earlier HIV testing, diagnosis at health care settings and later stage of the sub-epidemic.

CONCLUSIONS

The lower rate of late diagnosis in the first 4-year interval of each HIV sub-epidemic suggests that the early stages of the HIV epidemic in Finland were detected early. This factor may have contributed to the low prevalence of HIV infection in Finland. The stage and age of the epidemic should be taken into account when interpreting the data on late HIV diagnosis, especially in cross-country comparisons.

K(alpha) x-ray emission characterization of 100 Hz, 15 mJ femtosecond laser system with high contrast ratio

We report K(alpha) x-ray production with a high energy (110 mJ per pulse at 800 nm before compression/15 mJ at 400 nm after compression), high repetition rate (100 Hz), and high pulse contrast (better than 10(-9) at 400 nm) laser system. To develop laser-based x-ray sources for biomedical imaging requires to use high-energy and high-power ultra-fast laser system where compression is achieved under vacuum. Using this type of laser system, we demonstrate long-term stability of the x-ray yield, conversion efficiency higher than 1.5 x 10(-5) with a Mo target, and the x-ray spot size close to the optical focal spot. This high-repetition K(alpha) x-ray source can be very useful for x-ray phase-contrast imaging.

HCV-specific T-cell responses in injecting drug users: evidence for previous exposure to HCV and a role for CD4+ T cells focussing on nonstructural proteins in viral clearance

In order to understand the parameters associated with resolved hepatitis C virus (HCV)-infection, we analysed the HCV-specific T-cell responses longitudinally in 13 injecting drug-users (IDUs) with a prospectively identified acute HCV infection. Seven IDUs cleared HCV and six IDUs remained chronically infected. T-cell responses were followed in the period needed to resolve and a comparable time span in chronic carriers. Ex vivo T-cell responses were measured using interferon-gamma Elispot assays after stimulation with overlapping peptide pools spanning the complete HCV genome. CD4+ memory-T-cell responses were determined after 12-day stimulation with HCV proteins. The maximum response was compared between individuals. The T-cell responses measured directly ex vivo were weak but significantly higher in resolvers compared to chronic carriers, whereas the CD4+ memory-T-cell response was not different between resolvers and chronic carriers. However, HCV Core protein was targeted more often in chronic carriers compared to individuals resolving HCV infection. CD4+ T-cell responses predominantly targeting nonstructural proteins were associated with resolved HCV infection. Interestingly, observation of memory-T-cell responses present before the documented HCV-seroconversion suggests that reinfections in IDUs occur often. The presence of these responses however, were not predictive for the outcome of infection. However, a transition of the HCV-specific CD4+ memory-T-cell response from targeting Core to targeting nonstructural proteins during onset of infection was associated with a favourable outcome. Therefore, the specificity of the CD4+ memory-T-cell responses measured after 12-day expansion seems most predictive of resolved infection.

Ex vivo correction of selenoprotein N deficiency in rigid spine muscular dystrophy caused by a mutation in the selenocysteine codon

Premature termination of translation due to nonsense mutations is a frequent cause of inherited diseases. Therefore, many efforts were invested in the development of strategies or compounds to selectively suppress this default. Selenoproteins are interesting candidates considering the idiosyncrasy of the amino acid selenocysteine (Sec) insertion mechanism. Here, we focused our studies on SEPN1, a selenoprotein gene whose mutations entail genetic disorders resulting in different forms of muscular diseases. Selective correction of a nonsense mutation at the Sec codon (UGA to UAA) was undertaken with a corrector tRNA^Sec that was engineered to harbor a compensatory mutation in the anticodon. We demonstrated that its expression restored synthesis of a full-length selenoprotein N both in HeLa cells and in skin fibroblasts from a patient carrying the mutated Sec codon. Readthrough of the UAA codon was effectively dependent on the Sec insertion machinery, therefore being highly selective for this gene and unlikely to generate off-target effects. In addition, we observed that expression of the corrector tRNA^Sec stabilized the mutated SEPN1 transcript that was otherwise more subject to degradation. In conclusion, our data provide interesting evidence that premature termination of translation due to nonsense mutations is amenable to correction, in the context of the specialized selenoprotein synthesis mechanism.

An improved definition of the RNA-binding specificity of SECIS-binding protein 2, an essential component of the selenocysteine incorporation machinery

By binding to SECIS elements located in the 3′-UTR of selenoprotein mRNAs, the protein SBP2 plays a key role in the assembly of the selenocysteine incorporation machinery. SBP2 contains an L7Ae/L30 RNA-binding domain similar to that of protein 15.5K/Snu13p, which binds K-turn motifs with a 3-nt bulge loop closed by a tandem of G.A and A.G pairs. Here, by SELEX experiments, we demonstrate the capacity of SBP2 to bind such K-turn motifs with a protruding U residue. However, we show that conversion of the bulge loop into an internal loop reinforces SBP2 affinity and to a greater extent RNP stability. Opposite variations were found for Snu13p. Accordingly, footprinting assays revealed strong contacts of SBP2 with helices I and II and the 5′-strand of the internal loop, as opposed to the loose interaction of Snu13p. Our data also identifies new determinants for SBP2 binding which are located in helix II. Among the L7Ae/L30 family members, these determinants are unique to SBP2. Finally, in accordance with functional data on SECIS elements, the identity of residues at positions 2 and 3 in the loop influences SBP2 affinity. Altogether, the data provide a very precise definition of the SBP2 RNA specificity.

Selenoprotein synthesis: UGA does not end the story

It is well established that the beneficial effects of the trace element selenium are mediated by its major biological product, the amino acid selenocysteine, present in the active site of selenoproteins. These fulfill different functions, as varied as oxidation-reduction of metabolites in bacteria, reduction of reactive oxygen species, control of the redox status of the cell or thyroid hormone maturation. This review will focus on the singularities of the selenocysteine biosynthesis pathway and its unique incorporation mechanism into eukaryal selenoproteins. Selenocysteine biosynthesis from serine is achieved on tRNA(Sec) and requires four proteins. As this amino acid is encoded by an in-frame UGA codon, otherwise signaling termination of translation, ribosomes must be told not to stop at this position in the mRNA. Several molecular partners acting in cis or in trans have been identified, but their knowledge has not enabled yet to firmly establish the molecular events underlying this mechanism. Data suggest that other, so far uncharacterized factors might exist. In this survey, we attempted to compile all the data available in the literature and to describe the latest developments in the field.

Understanding the importance of selenium and selenoproteins in muscle function

Selenium is an essential trace element. In cattle, selenium deficiency causes dysfunction of various organs, including skeletal and cardiac muscles. In humans as well, lack of selenium is associated with many disorders, but despite accumulation of clinical reports, muscle diseases are not generally considered on the list. The goal of this review is to establish the connection between clinical observations and the most recent advances obtained in selenium biology. Recent results about a possible role of selenium-containing proteins in muscle formation and repair have been collected. Selenoprotein N is the first selenoprotein linked to genetic disorders consisting of different forms of congenital muscular dystrophies. Understanding the muscle disorders associated with selenium deficiency or selenoprotein N dysfunction is an essential step in defining the causes of the disease and obtaining a better comprehension of the mechanisms involved in muscle formation and maintenance.

Characterisation of systemic dissemination of nonreplicating adenoviral vectors from tumours in local gene delivery

Systemic virus dissemination is a potential problem during local gene delivery in solid tumours. However, the kinetics and pathways of the dissemination have not been well characterised during the first 24 h after the infusion is started. To this end, we infused adenoviral vectors for luciferase or enhanced green fluorescence protein into three different tumour models in mice. During and/or after the infusion, we determined the amount of adenoviruses in the tumour, blood, and liver, and examined the transgene expression in the liver, lung, blood, and tumour. In addition, we intravenously injected tumour cells expressing luciferase and examined the biodistribution of these cells in the body. We observed transgene expression in the liver and tumour at 24 h after the infusion, but could not detect transgene expression in the blood and lung. The peak concentration of viral vectors in the plasma occurred during the intratumoral infusion. At 10 min after the infusion, few viral vectors remained in the blood and the ratio of copy numbers of adenoviruses between liver and tumour was >2 in 80% and ⩾10 in 40% of the mice. Most tumour cells injected intravenously accumulated in the lung within the first 24 h. Taken together, these data indicated that systemic virus dissemination occurred mainly during the first 10 min after the intratumoral infusion was started, and that the dissemination was due to infusion-induced convective transport of viral vectors into leaky tumour microvessels.

Effects of cell damage and glycosaminoglycan degradation on available extravascular space of different dextrans in a rat fibrosarcoma

Drug delivery to solid tumors may be enhanced through increasing the available volume fraction (K(AV)) of drugs. Therefore, two approaches were investigated that may increase K(AV) of dextrans in a rat fibrosarcoma: (a) damaging cells in tumours via ex vivo incubation of tumour tissues, and (b) degrading tumour glycosaminoglycans (GAGs) with exogenous hyaluronidase. The molecular weights of dextrans used in this study were approximately 10,000 (D10), 70,000 (D70) and 2,000,000 (D2000), respectively. It was found that GAG degradation had minimal effects on K(AV) of dextrans. Ex vivo incubation at 37 degrees C for up to 3 h caused only minor cell damage and had minimal effects on K(AV) of D10 and D70. However, the ex vivo incubation reduced K(AV) of D2000 (p < 0.05). When the incubation at 37 degrees C was maintained for 20 h, the amount of viable cells in tumours was reduced by 56% and K(AV) of all dextrans were significantly increased (p < 0.05). Ex vivo incubation at 41 degrees C for 3 h caused similar cell damage to that at 37 degrees C for 20 h, but only K(AV) of D10 and D70 were increased significantly (p < 0.05). There was no significant change in K(AV) of D2000, although it was higher than that in tumours incubated at 37 degrees C for 3 h (p < 0.05). These data suggest that cell damage is a more effective approach than GAG degradation for increasing K(AV) of macromolecules and that the amount of increase depends on the degree of cell damage and the size of molecules.

Randomized placebo-controlled trial of metronidazole 1% cream with sunscreen SPF 15 in treatment of rosacea

BACKGROUND

Rosacea is a photoaggravated dermatosis responsive to treatment with topical and oral antibiotics. A formulation combining metronidazole 1% cream with sunscreen SPF 15 was developed for the treatment of rosacea.

OBJECTIVE

The objective of this study was to determine the safety and efficacy of a formulation combining metronidazole 1% cream with sunscreen SPF 15 in the treatment of moderate to severe rosacea.

METHODS

One hundred and twenty patients with moderate to severe rosacea were enrolled for a randomized, placebo-controlled (vehicle containing sunscreen with SPF 15), double-blind study. Study cream was applied twice daily to the entire face over a 12-week period.

RESULTS

Treatment with metronidazole 1% cream with sunscreen SPF 15 resulted in significant improvement (p <0.05) in inflammatory lesion count, erythema and telangiectasiae scores, and investigator and patient global assessment scores compared with baseline and placebo. Adverse reactions related to study medication were typically mild, occurred at the site of application, and were reversible. There was no difference between the safety profiles of metronidazole 1% cream with sunscreen SPF 15 and placebo.

CONCLUSIONS

The combined topical formulation of metronidazole 1% cream with sunscreen SPF 15 was an effective, well-tolerated topical agent for the treatment of moderate to severe rosacea.

Modeling the axial extension of a transmission line source within iterative reconstruction via multiple transmission sources

Reconstruction algorithms for transmission tomography have generally assumed that the photons reaching a particular detector bin at a particular angle originate from a single point source. In this paper, we highlight several cases of extended transmission sources, in which it may be useful to approach the estimation of attenuation coefficients as a problem involving multiple transmission point sources. Examined in detail is the case of a fixed transmission line source with a fan-beam collimator. This geometry can result in attenuation images that have significant axial blur. Herein it is also shown, empirically, that extended transmission sources can result in biased estimates of the average attenuation, and an explanation is proposed. The finite axial resolution of the transmission line source configuration is modeled within iterative reconstruction using an expectation-maximization algorithm that was previously derived for estimating attenuation coefficients from single photon emission computed tomography (SPECT) emission data. The same algorithm is applicable to both problems because both can be thought of as involving multiple transmission sources. It is shown that modeling axial blur within reconstruction removes the bias in the average estimated attenuation and substantially improves the axial resolution of attenuation images.

Acute generalized exanthematous pustulosis induced by oral fluconazole

BACKGROUND

Acute generalized exanthematous pustulosis (AGEP) is a generalized, nonfollicular, pustular eruption of the skin associated with fever and leukocytosis. The cause of AGEP has mainly been attributed to drugs.

OBJECTIVE

We report a unique case of AGEP in a 75-year-old male caused by oral fluconazole. We include clinical as well as histological illustrations of our case.

CONCLUSION

Based on a current literature search using the MEDLINE electronic database, this is the first reported case of AGEP arising from use of oral fluconazole. The clinical presentation, clinical course, and histology are consistent with prior reports of AGEP resulting from other drugs. AGEP should be considered a possible complication of oral fluconazole treatment.

Available space and extracellular transport of macromolecules: effects of pore size and connectedness

Molecular exclusion in tumor tissues is one of the limiting factors for drug delivery to tumor cells. It can be quantified by the available volume fraction of solutes (K(AV)). We found in a previous study that K(AV) of dextran in tumor tissues decreased sharply when the molecular weight (MW) of dextran was increased from 40,000 to 70,000. Outside this range, K(AV) was less sensitive to the MW of dextran. To understand the mechanisms of the MW dependence of K(AV), we investigated K(AV) in tissue phantoms composed of tumor cells in 1% agarose gels, and performed numerical simulations of the available volume fraction in pore networks. We found that the MW dependence of K(AV) in tissue phantoms was similar to that in tumor tissues when the volume fraction of cells in the former was approximately 30%. Our numerical simulations revealed that the sharp decrease in K(AV) required two necessary conditions: (i) the existence of at least two populations of pores and (ii) the lack of connectedness of available pores in the interstitial space. Furthermore, results in this study suggest that it is important to consider not only the local structures of pores but also their connectedness in analyses of molecular transport in tissues.

The selenocysteine incorporation machinery: interactions between the SECIS RNA and the SECIS-binding protein SBP2

The decoding of UGA as a selenocysteine (Sec) codon in mammalian selenoprotein mRNAs requires a selenocysteine insertion sequence (SECIS) element in the 3' untranslated region. The SECIS is a hairpin structure that contains a non-Watson-Crick base-pair quartet with a conserved G.A/A.G tandem in the core of the upper helix. Another essential component of the Sec insertion machinery is SECIS-binding protein 2 (SBP2). In this study, we define the binding site of SBP2 on six different SECIS RNAs using enzymatic and hydroxyl radical footprinting, gel mobility shift analysis, and phosphate-ethylation binding interference. We show that SBP2 binds to a variety of mammalian SECIS elements with similar affinity and that the SBP2 binding site is conserved across species. Based on footprinting studies, SBP2 protects the proximal part of the hairpin and both strands of the lower half of the upper helix that contains the non-Watson-Crick base pair quartet. Gel mobility shift assays showed that the G.A/A.G tandem and internal loop are critical for the binding of SBP2. Modification of phosphates by ethylnitrosourea along both strands of the non-Watson-Crick base pair quartet, on the 5' strand of the lower helix and part of the 5' strand of the internal loop, prevented binding of SBP2. We propose a model in which SBP2 covers the central part of the SECIS RNA, binding to the non-Watson-Crick base pair quartet and to the 5' strands of the lower helix and internal loop. Our results suggest that the affinity of SBP2 for different SECIS elements is not responsible for the hierarchy of selenoprotein expression that is observed in vivo.

An unusually compact external promoter for RNA polymerase III transcription of the human H1RNA gene

H1 RNA, the RNA component of the human nuclear RNase P, is encoded by a unique gene transcribed by RNA polymerase III (Pol III). In this work, cis-acting elements and trans-acting factors involved in human H1 gene transcription were characterized by transcription assays of mutant templates and DNA binding assays of recombinant proteins. Four elements, lying within 100 bp of 5'-flanking sequences, were defined to be essential for maximal in vitro and in vivo expression, consisting of the octamer, Staf, proximal sequence element (PSE) and TATA motifs. These are also encountered in the promoter elements of vertebrate snRNA genes, where the first two constitute the distal sequence element (DSE). In all the genes examined so far, the DSE is distant from the PSE and TATA box that compose the basal promoter. However, we observed a fundamental difference in the organization of the H1 RNA and snRNA gene promoters with respect to the relative spacing of the DSE and PSE. Indeed, the H1 promoter is unusually compact, with the octamer motif and Staf binding site adjacent to the PSE and TATA motifs. It thus appears that the human RNase P RNA gene has adopted a unique promoter strategy placing the DSE immediately adjacent to the basal promoter.

An EM algorithm for estimating SPECT emission and transmission parameters from emissions data only

A maximum-likelihood (ML) expectation-maximization (EM) algorithm (called EM-IntraSPECT) is presented for simultaneously estimating single photon emission computed tomography (SPECT) emission and attenuation parameters from emission data alone. The algorithm uses the activity within the patient as transmission tomography sources, with which attenuation coefficients can be estimated. For this initial study, EM-IntraSPECT was tested on computer-simulated attenuation and emission maps representing a simplified human thorax as well as on SPECT data obtained from a physical phantom. Two evaluations were performed. First, to corroborate the idea of reconstructing attenuation parameters from emission data, attenuation parameters (mu) were estimated with the emission intensities (lambda) fixed at their true values. Accurate reconstructions of attenuation parameters were obtained. Second, emission parameters lambda and attenuation parameters mu were simultaneously estimated from the emission data alone. In this case there was crosstalk between estimates of lambda and mu and final estimates of lambda and mu depended on initial values. Estimates degraded significantly as the support extended out farther from the body, and an explanation for this is proposed. In the EM-IntraSPECT reconstructed attenuation images, the lungs, spine, and soft tissue were readily distinguished and had approximately correct shapes and sizes. As compared with standard EM reconstruction assuming a fix uniform attenuation map, EM-IntraSPECT provided more uniform estimates of cardiac activity in the physical phantom study and in the simulation study with tight support, but less uniform estimates with a broad support. The new EM algorithm derived here has additional applications, including reconstructing emission and transmission projection data under a unified statistical model.

Distinctive features in the SelB family of elongation factors for selenoprotein synthesis. A glimpse of an evolutionary complexified translation apparatus

The last ten years have seen a dramatic increase in our understanding of the molecular mechanism allowing specific incorporation of selenocysteine into selenoproteins. Whether in prokaryotes or eukaryotes, this incorporation requires several gene products, among which the specialized elongation factor SelB and the tRNA(Sec) play a pivotal role. While the molecular actors have been discovered and their role elucidated in the eubacterial machinery, recent data from our and other laboratories pointed to a higher degree of complexity in archaea and eukaryotes. These findings also revealed that more needs to be discovered in this area. This review will focus on phylogenetic aspects of the SelB proteins. In particular, we will discuss the concerted evolution that occurred within the SelB/tRNA(Sec) couples, and also the distinctive roles carried out by the SelB C-terminal domains in eubacteria on the one side, and archaea and eukaryotes, on the other.

Characterization of mSelB, a novel mammalian elongation factor for selenoprotein translation

Decoding of UGA selenocysteine codons in eubacteria is mediated by the specialized elongation factor SelB, which conveys the charged tRNA(Sec) to the A site of the ribosome, through binding to the SECIS mRNA hairpin. In an attempt to isolate the eukaryotic homolog of SelB, a database search in this work identified a mouse expressed sequence tag containing the complete cDNA encoding a novel protein of 583 amino acids, which we called mSelB. Several lines of evidence enabled us to establish that mSelB is the bona fide mammalian elongation factor for selenoprotein translation: it binds GTP, recognizes the Sec-tRNA(Sec) in vitro and in vivo, and is required for efficient selenoprotein translation in vivo. In contrast to the eubacterial SelB, the recombinant mSelB alone is unable to bind specifically the eukaryotic SECIS RNA hairpin. However, complementation with HeLa cell extracts led to the formation of a SECIS-dependent complex containing mSelB and at least another factor. Therefore, the role carried out by a single elongation factor in eubacterial selenoprotein translation is devoted to two or more specialized proteins in eukaryotes.

Junctional epidermolysis bullosa with pyloric stenosis presenting with electron microscopic findings suggestive of epidermolysis bullosa simplex

We present an infant girl who was born with pyloric stenosis and epidermolysis bullosa (EB). Electron microscopy of a skin biopsy specimen showed findings suggestive of EB simplex, but immunofluorescence (IF) mapping of the same specimen established the diagnosis of junctional EB. Because electron microscopy findings may sometimes be misleading, an EB patient with pyloric stenosis and electron microscopy findings suggestive of EB simplex should have a biopsy specimen examined by immunofluorescence mapping, which may confirm that the patient in fact has junctional EB.

Structural analysis of new local features in SECIS RNA hairpins

Decoding of the UGA selenocysteine codon for selenoprotein translation requires the SECIS element, a stem-loop motif in the 3'-UTR of the mRNA carrying short or large apical loops. In previous structural studies, we derived a secondary structure model for SECIS RNAs with short apical loops. Work from others proposed that intra-apical loop base pairing can occur in those SECIS that possess large apical loops, yielding form 2 SECIS versus the form 1 with short loops. In this work, SECIS elements arising from eight different selenoprotein mRNAs were assayed by enzymatic and/or chemical probing showing that seven can adopt form 2. Further, database searches led to the discovery in drosophila and zebrafish of SECIS elements in the selenophosphate synthetase 2, type 1 deiodinase and SelW mRNAs. Alignment of SECIS sequences not only highlighted the predominance of form 2 but also made it possible to classify the SECIS elements according to the type of selenoprotein mRNA they belong to. Interestingly, the alignment revealed that an unpaired adenine, previously thought to be invariant, is replaced by a guanine in four SECIS elements. Tested in vivo, neither the A to G nor the A to U changes at this position greatly affected the activity while the most detrimental effect was provided by a C. The putative contribution of the various SECIS motifs to function and ligand binding is discussed.

Diffuse neonatal haemangiomatosis

A newborn girl with severe diffuse neonatal haemangiomatosis is described. She was treated with high dose systemic corticosteroids and high dose interferon-alpha-2a, but with fatal outcome. A review of the current literature is presented.

Structural organization of Staf-DNA complexes

The transactivator Staf, which contains seven contiguous zinc fingers of the C(2)-H(2)type, exerts its effects on gene expression by binding to specific targets in vertebrate small nuclear RNA (snRNA) and snRNA-type gene promoters. Here, we have investigated the interaction of the Staf zinc finger domain with the optimal Xenopus selenocysteine tRNA (xtRNA(Sec)) and human U6 snRNA (hU6) Staf motifs. Generation of a series of polypeptides containing increasing numbers of Staf zinc fingers tested in binding assays, by interference techniques and by binding site selection served to elucidate the mode of interaction between the zinc fingers and the Staf motifs. Our results provide strong evidence that zinc fingers 3-6 represent the minimal zinc finger region for high affinity binding to Staf motifs. Furthermore, we show that the binding of Staf is achieved through a broad spectrum of close contacts between zinc fingers 1-6 and xtRNA(Sec)or optimal sites or between zinc fingers 3-6 and the hU6 site. Extensive DNA major groove contacts contribute to the interaction with Staf that associates more closely with the non-template than with the template strand. Based on these findings and the structural information provided by the solved structures of other zinc finger-DNA complexes, we propose a model for the interaction between Staf zinc fingers and the xtRNA(Sec), optimal and hU6 sites.

Trigonal prismatic vs octahedral coordination geometry: syntheses and structural characterization of hexakis(arylthiolato) zirconate complexes

Treating [Li(tmeda)]2[Zr(CH3)6] with aryl thiols, HSC6H4-4-R, in a 1:6 stoichiometry in diethyl ether affords excellent yields of [Li(tmeda)]2[Zr(SC6H4-4-R)6], where R = CH3 (1(2-)) or OCH3 (2(2-)) and tmeda denotes N,N,N',N'-tetramethylethylenediamine. These complexes are air-sensitive canary-yellow solids, soluble in hexane, diethyl ether, THF, and acetonitrile, that form yellow single crystals of [Li(tmeda)](2)1 (diethyl ether solution) or [Li(THF)3](2)2 (THF solution) from saturated solutions at -20 degrees C. Both complexes were characterized by X-ray crystallography and consist of a zirconium atom coordinated solely by the sulfur atoms of six aryl thiolate ligands in a nonoctahedral geometry. In each structure the lithium cation coordinates to the three sulfur atoms on the triangular faces of the S6 pseudotrigonal prism. These lithium-sulfur interactions appear to play a role in determining the coordination geometry about the metal center by orienting the sulfur lone pairs of electrons slightly out of the plane defined by the S3 triangular face and tilted away from the zirconium atoms. A likely consequence is the positioning of the sulfur lone pairs of electrons away from orthogonality with the zirconium-sulfur vector, and hence, they are poorly arranged to pi-interact with zirconium. Complex 1(2-) with a twist angle of ca. 9.18 degrees (trigonal prism, 0 degree; octahedron, 60 degrees) agrees with the interpretations of computational studies on d degree complexes, which suggest that a nearly trigonal prismatic geometry is favored when the interaction between metal and ligand is primarily through sigma-bonds. The intrinsically weak pi-donor thiolate ligand is probably converted to a primarily sigma-bonding system by the lithium-sulfur interaction. On the other hand complex 2(2-) with a twist angle of ca. 30.38 degrees is trigonally twisted to the midpoint of the trigonal prismatic-to-octahedral reaction coordinate. In complex 2(2-) the 4-OCH3 group is an electron donor by resonance effects that possibly may lead to the movement away from the expected trigonal prismatic geometry due to either pi-interactions or electrostatics repulsion.

The selenocysteine insertion sequence binding protein SBP is different from the Y-box protein dbpB

In eukaryotes, translation of internal UGA selenocysteine codons requires the SECIS stem-loop structure in the 3'UTR of selenoprotein mRNAs. In an earlier work, we identified SBP as a selenocysteine insertion sequence (SECIS)-binding protein. Here, the yeast three-hybrid screen was employed to capture the cDNA of SBP. One candidate, satisfying the genetic screens, was identified as the already known dbpB protein. Although it was also found by another group, but with a different strategy, to carry SECIS-binding activity, further experiments enabled us to show that dbpB was unable to bind the SECIS element in vitro. Altogether, our findings led us to conclude that, under our conditions, dbpB and SBP are two distinct proteins.

Novel selenoproteins identified in silico and in vivo by using a conserved RNA structural motif

Selenocysteine is incorporated into selenoproteins by an in-frame UGA codon whose readthrough requires the selenocysteine insertion sequence (SECIS), a conserved hairpin in the 3'-untranslated region of eukaryotic selenoprotein mRNAs. To identify new selenoproteins, we developed a strategy that obviates the need for prior amino acid sequence information. A computational screen was used to scan nucleotide sequence data bases for sequences presenting a potential SECIS secondary structure. The computer-selected hairpins were then assayed in vivo for their functional capacities, and the cDNAs corresponding to the SECIS winners were identified. Four of them encoded novel selenoproteins as confirmed by in vivo experiments. Among these, SelZf1 and SelZf2 share a common domain with mitochondrial thioredoxin reductase-2. The three proteins, however, possess distinct N-terminal domains. We found that another protein, SelX, displays sequence similarity to a protein involved in bacterial pilus formation. For the first time, four novel selenoproteins were discovered based on a computational screen for the RNA hairpin directing selenocysteine incorporation.

Maximization of selenocysteine tRNA and U6 small nuclear RNA transcriptional activation achieved by flexible utilization of a Staf zinc finger

Transcriptional activators Staf and Oct-1 play critical roles in the activation of small nuclear RNA (snRNA) and snRNA-type gene transcription. Recently, we established that Staf binding to the human U6 snRNA (hU6) and Xenopus selenocysteine tRNA (xtRNA(Sec)) genes requires different sets of the seven C2-H2 zinc fingers. In this work, using a combination of oocyte microinjection, electrophoretic mobility shift assays, and missing nucleoside experiments with wild-type and mutant promoters, we demonstrate that the hU6 gene requires zinc fingers 2-7 for Staf binding and Oct-1 for maximal transcriptional activity. In contrast, the xtRNA(Sec) gene needs the binding of the seven Staf zinc fingers, but not Oct-1, for optimal transcriptional capacity. Mutation in the binding site for Staf zinc finger 1 in the tRNA(Sec) promoter reduced both Staf binding and transcriptional activity. Conversely, introduction of a zinc finger 1 binding site in the hU6 promoter increased Staf binding but interfered with the simultaneous Staf and Oct-1 binding, thus reducing transcriptional activity. Collectively, these results show that the differential utilization of Staf zinc finger 1 represents a new, critical determinant of the transcriptional activation mechanism for the Xenopus tRNA(Sec) and human U6 snRNA genes.

Flexible zinc finger requirement for binding of the transcriptional activator staf to U6 small nuclear RNA and tRNA(Sec) promoters

The transactivator Staf, which contains seven zinc finger motifs, exerts its effect on gene expression by binding to specific targets in small nuclear RNA (snRNA) and snRNA-type gene promoters. In this work, binding site selection allowed us to identify the 21-base pair ATTACCCATAATGCATYGCGG sequence as the high affinity consensus binding site for Staf. It shows a high sequence divergence with Staf-responsive elements in the Xenopus selenocysteine tRNA (tRNA(Sec)) and human U6 snRNA promoters. By using a combination of approaches, we analyzed the interaction of wild-type and truncated Staf zinc finger domains with the consensus, Xenopus tRNA(Sec), and human U6 sites. Two main conclusions emerged from our data. First, the data clearly indicate that zinc finger 7 does not establish base-specific contacts in Staf-DNA complexes. The second conclusion concerns zinc finger 1, which is required for the binding to the Xenopus tRNA(Sec) site but is dispensable in the case of the human U6 site. Taking into account the sequence differences in the two sites, these findings demonstrate that Staf utilizes zinc finger 1 in a rather flexible manner, illustrating how a protein can interact with DNAs containing targets of different sequences.

Available volume fraction of macromolecules in the extravascular space of a fibrosarcoma: implications for drug delivery

Steric exclusion of molecules in the extravascular space of tissues can be quantified by the available volume fraction (K(AV)). Despite its clinical importance, however, there is a paucity of data in the literature regarding the available volume fraction of macromolecules in the extravascular space of tumor tissues. In this study, we quantified K(AV) of inulin, BSA, and dextran molecules of Mr 10,000-2,000,000 in polymer gels and fibrosarcoma tissues. The measurement involved: (a) sectioning of gels or tumor tissues into thin slices (approximately 600 microm) using a Vibratome, (b) ex vivo incubation of the slices in solutions containing fluorescently labeled tracers, and (c) quantification of the equilibrium tracer concentrations in both slices and solutions. We found that K(AV) in gels decreased monotonically when the Mr of dextran was increased from Mr 10,000 to 2,000,000. However, K(AV) in tumor tissues was insensitive to the molecular weight of dextran in the range between Mr 10,000 and 40,000. There was a sharp decrease in K(AV) from 0.28 +/- 0.14 to 0.10 +/- 0.06 when the molecular weight was increased from Mr 40,000 to 70,000. In addition to the molecular weight dependence, K(AV) was heterogeneous in tumors, with intertumoral difference being greater than intratumoral variation. The interstitial fluid space, which was quantified by K(AV) of inulin, was 50% of the total tissue volume. These data indicate that the fraction of the extravascular volume in tumors that is accessible to large therapeutic agents is heterogeneous and depends on the size of agents.

Eccrine angiomatous hamartoma: report of a case and literature review

Eccrine angiomatous hamartoma is a rare condition characterized histologically by increased numbers of eccrine structures and numerous capillary channels. Patients characteristically have a solitary, congenital nodule that may be painful and that may show hyperhidrosis. It is important to recognize this condition because it is a benign lesion for which aggressive treatment is not indicated. We report the case of a congenital eccrine angiomatous hamartoma that had a firm nodule studded with blue papules.