bluuebunny/crossref_metadata_2025 huggingface dataset:
Bone marrow stromal cells as a genetic platformfor systemic delivery of therapeutic proteins in vivo: human factor IX model
Authors: Krebsbach Paul H. , Zhang Kezhong , Malik Ajay K. , Kurachi Kotoku
Published: January 2003

Background

Hemophilia B is an X‐linked bleeding disorder that results from a deficiency in functional coagulation factor IX (hFIX). In patients lacking FIX, the intrinsic coagulation pathway is disrupted leading to a lifelong, debilitating and sometimes fatal disease.

Methods

We have developed an ex vivo gene therapy system using genetically modified bone marrow stromal cells (BMSCs) as a platform for sustained delivery of therapeutic proteins into the general circulation. This model exploits the ability of BMSCs to form localized ectopic ossicles when transplanted in vivo. BMSCs were transduced with MFG‐hFIX, a retroviral construct directing the expression of hFIX. The biological activity of hFIX expressed by these cells was assessed in vitro and in vivo.

Results

Transduced cells produced biologically active hFIX in vitro with a specific activity of 90% and expressed hFIX at levels of ∼497 ng/106 cells/24 h and 322 ng/106 cells/24 h for human and porcine cells, respectively. The secretion of hFIX was confirmed by Western blot analysis of the conditioned medium using a hFIX‐specific antibody. Transduced BMSCs (8 × 106 cells per animal) were transplanted within scaffolds into subcutaneous sites in immunocompromised mice. At 1 week post‐implantation, serum samples contained hFIX at levels greater than 25 ng/ml. Circulating levels of hFIX gradually decreased to 11.5 ng/ml at 1 month post‐implantation and declined to a stable level at 6.1 ng/ml at 4 months.

Conclusions

These findings demonstrate that genetically modified BMSCs can continuously secrete biologically active hFIX from self‐contained ectopic ossicles in vivo, and thus represent a novel delivery system for releasing therapeutic proteins into the circulation. Copyright © 2002 John Wiley & Sons, Ltd.
Uptake of plasmid/glycosylated polymer complexes and gene transfer efficiency in differentiated airway epithelial cells
Authors: Fajac Isabelle , Thévenot Guiti , Bédouet Laurent , Danel Claire , Riquet Marc , Merten Marc , Figarella Catherine , Ava‐Santucci Josette Dall' , Monsigny Michel , Briand Pascale
Published: January 2003

Background

We have studied gene transfer efficiency of glycosylated polylysines and glycosylated polyethylenimines as vectors in immortalized differentiated airway gland serous cells and primary cultures of human airway surface epithelial cells.

Methods

In both cell types, lactosylated PEI was more efficient for gene transfer than unsubstituted PEI and lactosylated polylysine which requires the presence of endosomolytic agents. However, for all the vectors tested, gene transfer efficiency was lower in differentiated cells as compared with poorly differentiated cells. The presence of membrane lectins, i.e. cell surface sugar‐specific receptors, was evaluated using fluorescein‐conjugated neoglycoproteins and microscopy or flow cytometry. In differentiated airway surface epithelial cells, membrane lectins were not expressed and plasmid DNA/fluorescein‐conjugated glycosylated polymer complexes were not incorporated. This accounted in part for the lack of gene transfer efficiency in these cells. In contrast, in differentiated airway gland serous cells, expression of lectins and their endocytotic properties appeared to be similar to that observed in undifferentiated cells, and plasmid DNA/fluorescein‐conjugated glycosylated polymer complexes were incorporated in similar amounts by cells in both differentiated states.

Results

Glycosylated PEI appears to be a promising gene delivery system since it is more efficient than the sugar‐free polymer and does not require endosomolytic agents. However, in differentiated airway gland serous cells, a low gene transfer efficiency was observed that could not be attributed to low expression of membrane lectins or low uptake of glycosylated complexes. An impaired intracellular trafficking of glycosylated complexes in differentiated airway gland serous cells is suggested. Copyright © 2002 John Wiley & Sons, Ltd.
Upregulation of expression from the FRDA genomic locus for the therapy of Friedreich ataxia
Authors: Sarsero Joseph P. , Li Lingli , Wardan Hady , Sitte Karin , Williamson Robert , Ioannou Panos A.
Published: January 2003

Background

Friedreich ataxia is a slowly progressive neurodegenerative disease caused by reduced expression of frataxin as a result of a GAA repeat expansion in the first intron of the FRDA gene. We report here the development of a sensitive cellular assay for frataxin expression from the intact FRDA locus that should facilitate the identification of potentially therapeutic pharmacological agents to treat Friedreich ataxia.

Methods

PAC and BAC clones containing the entire human FRDA functional genomic sequence were identified and shown to express FRDA mRNA. The GET Recombination system was used to insert cassettes consisting of the gene encoding EGFP linked to a kanamycin/neomycin resistance determinant into a BAC clone containing the entire FRDA gene and surrounding regions.

Results

Two in‐frame fusions between the FRDA gene and a gene coding for enhanced green fluorescent protein (EGFP) were constructed. One fusion is within exon 2 of the FRDA gene. The other is at the end of exon 5a, containing the entire frataxin protein fused to EGFP. Both constructs were shown to drive the expression of EGFP from the regulatory elements of the FRDA locus, with the frataxin‐EGFP fusion proteins targeted to the mitochondria. Stable cell lines containing the EGFP fusion in exon 5a were produced. Enhancement of FRDA gene expression by hemin and butyric acid was demonstrated.

Conclusions

Expression studies with FRDA‐EGFP fusion constructs will facilitate delineation of regulatory elements determining the tissue and developmental specificity of FRDA gene expression. These constructs should also facilitate screening for pharmacological compounds that can modulate the expression of the FRDA gene in a clinically relevant manner. Copyright © 2002 John Wiley & Sons, Ltd.
A modified finite‐difference time‐domain method for analysing field‐to‐transmission line coupling of telecommunication system signals
Authors: Trakadas P.T. , Kouveliotis N.K. , Capsalis C.N.
Published: January 2003

A modified finite‐difference time‐domain (FDTD) code is presented for the line response characterization of a transmission line illuminated by a Gaussian pulse‐modulated electromagnetic signal. The final expressions are transformed according to the complex‐envelope representation in order to omit the high‐frequency carrier contribution and thus provide an accurate solution of the coupling phenomenon by avoiding the computational burden of the conventional FDTD algorithm. Comparison results between the conventional FDTD method and the modified one are presented, showing the advantages of the novel method. Copyright © 2002 John Wiley & Sons, Ltd.
Comparison of HEMT non‐linear model extraction approaches based on small signal and on large signal measurements
Authors: Carmen Currás‐Francos M.
Published: January 2003

In this paper the extraction of a non‐linear model for a HEMT is undertaken by means of two different approaches. The first approach is the classical procedure that consists of using the small signal data to fully generate a non‐linear model. The second alternative is developed following a different tactics that uses directly the response of the device to a large signal stimulus. Both approaches are compared in terms of required extraction measurements and limits of application. Copyright © 2002 John Wiley & Sons, Ltd.
Ultrastructural changes elicited by a non‐ablative wrinkle reduction laser
Authors: Omi Tokuya , Kawana Seiji , Sato Shigeru , Honda Mitsuyoshi
Published: January 2003

Background and Objectives

Cosmeceuticals, chemical peels and collagen injections are used to rejuvenate skin, but none of these methods is effective or permanent. Recently, laser resurfacing has been found to be effective, but the incidence of side effects is relatively high. Two years ago, the non‐ablative wrinkle reduction laser (N‐Lite, ICN Photonics, UK) was developed, and there have been several reports about its clinical effectiveness. In this study, we have investigated ultrastructural changes elicited by exposure to the N‐Lite laser.

Study Design/Materials and Methods

Eight adult volunteers were recruited for this study. They were treated with the N‐Lite laser and 3‐mm skin punch biopsies were obtained 3 hours, 1 day, 3 days, 1 week, 2 weeks, 4 weeks and 5 weeks after the laser exposure. These specimens were examined by electron microscopy.

Results

Three hours after the laser therapy, the capillaries showed endothelial cell edema with hemostasis and marked edema was observed around them. Neutrophils, monocytes and mast cells were observed in the extravascular dermis. These acute dermal inflammatory changes were observed until 1 week after the laser treatment. Two weeks after the laser treatment, the capillaries showed an almost normal structure, and dermal edema was not observed around them. New elastic fibers and collagen fibers had increased around the capillaries. Four weeks after the laser treatment, interstitial fibrosis was observed around the capillaries.

Conclusions

N‐Lite laser irradiation leads to interstitial fibrosis, especially around the capillaries, 4 weeks after the laser irradiation. Lasers Surg. Med. 32:46–49,2003. © 2003 Wiley‐Liss, Inc.
Detection and diagnosis of oral cancer by light‐induced fluorescence
Authors: Ebihara Arata , Krasieva Tatiana B. , Liaw Lih‐Huei L. , Fago Sheri , Messadi Diana , Osann Kathryn , Wilder‐Smith Petra
Published: January 2003

Background and Objective

New techniques for non‐invasive early detection and diagnosis of oral dysplasia and carcinoma are required. Our objective was to determine in the hamster cheek pouch model whether differentiation between the healthy tissue and the different stages of oral premalignancy and malignancy is possible using laser‐induced fluorescence after tissue exposure to 5‐Aminolevulinic acid (ALA).

Study Design/Materials and Methods

DMBA carcinogenesis was applied to one cheek pouch in 18 hamsters for 0–20 weeks. Prior to sacrifice, 20% ALA was applied to the cheek tissues. Excised cheek tissues were cryosectioned and imaged using fluorescence microscopy with excitation at 405 nm, detection at 635 nm. After fluorescence measurement, H&E staining and histopathological evaluation were performed.

Results

Fluorescence intensity was significantly lower in healthy tissue than in pathological tissues. Significantly higher intensities and more “fluorescence hot spots” occurred in severe dysplasia and carcinoma than in healthy tissue, hyperkeratosis, mild and moderate dysplasia.

Conclusions

Light‐induced fluorescence after ALA exposure can differentiate between the different stages of premalignancy and malignancy. Its ability to differentiate between healthy tissue and early pathology is particularly interesting Lasers Surg. Med. 32:17–24,2003. © 2003 Wiley‐Liss, Inc.
Basic study on vibrations during tooth preparations caused by high‐speed drilling and Er:YAG laser irradiation
Authors: Takamori Kazunori , Furukawa Hirohiko , Morikawa Yoshikatsu , Katayama Tadashi , Watanabe Shigeru
Published: January 2003

Background and Objectives

An Er:YAG laser effectively removes dental hard substance, and causes less pain during tooth preparations than high‐speed drilling. This laser was introduced to eliminate the noise, vibration, pressure, and heat associated with the high‐speed drilling. However, the difference in tooth vibration caused by the Er:YAG laser and the high‐speed drill is unclear. Therefore, the aim of this study was to evaluate tooth vibration obtained with the Er:YAG laser and high‐speed drill.

Study Design/Materials and Methods

Each of the five extracted permanent upper first premolars were built up in a plaster box. In this study, a silicone impression material was selected to simulate periodontal tissue. The vibration speed was measured by using a laser Doppler vibrometer.

Results

The Er:YAG laser irradiation energy was 50, 100, 145, 199, 300, and 350 mJ. As irradiation energy increased, vibration of the tooth also rose; a high‐correlation coefficient was observed between them. We found that only a small amount of the tooth vibration occurred with the Er:YAG laser preparations. The mean vibration speed and standard deviation with the laser were 166 ± 28 μm/second when the output energy was 145 mJ, whereas those with the high‐speed drill were 65 ± 48 mm/second. The frequency characteristic approached 230 Hz and 5 kHz, respectively.

Conclusions

These results show that the high‐speed drilling causes greater tooth vibration and has a frequency spectrum near the high sensitivity of hearing compared to the Er:YAG laser. This suggests a potential factor in provoking pain and displeasure during tooth preparation. Future study to examine the relationship of pain and amount of tooth vibration will be planned. Lasers Surg. Med. 32:25–31,2003. © 2003 Wiley‐Liss, Inc.
Spectral response for laser enhancement in hepatic regeneration for hepatectomized rats
Authors: Castro‐e‐Silva O. , Zucoloto S. , Marcassa L.G. , Marcassa J. , Kurachi C. , Melo C.A.S. , Ramalho F.S. , Ramalho L.N.Z. , Bagnato V.S.
Published: January 2003

Background and Objectives

The low intensity laser therapy (LILT) has been widely used in all medical fields due to its therapeutic effects in reparative process, pain relief, and biostimulation. Even though there is a therapeutic window of wavelengths for clinical application, little has been done concerning the frequency spectrum response to biological effects. In this work, we investigate the dependence of different wavelengths irradiation in the enhancement of the tissue regeneration after partial hepatectomy in Wistar rats.

Study Design/Materials and Methods

The proliferating cell nuclear antigen (PCNA) labeling index and the respiratory control (oxygen consumption in extracted mitochondria) were the tests used to evaluate the liver regeneration after laser irradiation with different wavelengths.

Results and Conclusions

The results show a correlated spectral response that can be explained based on the combined effect of light penetration on biological tissues and the biomolecular excitation efficiency for each wavelength used. Lasers Surg. Med. 32:50–53,2003. © 2003 Wiley‐Liss, Inc.
Quantitative assessment of chondrocyte viability after laser mediated reshaping: A novel application of flow cytometry
Authors: Rasouli Alexandre , Sun Chung‐Ho , Basu Reshmi , Wong Brian J.F.
Published: January 2003

Background and Objectives

Lasers can be used to reshape cartilage by accelerating mechanical stress relaxation. In this study, fluorescent differential cell viability staining and flow cytometry were used to determine chondrocyte viability following laser heating.

Study Design/Materials and Methods

Porcine septal cartilages were irradiated with an Nd:YAG laser (λ = 1.32 μm, 25 W/cm2) while surface temperature, stress relaxation, and diffuse reflectance were recorded. Each slab received one, two, or three laser exposures (respective exposure times of 6.7, 7.2, 10 seconds). Irradiated samples were then divided into two groups analyzed immediately and at 5 days following laser exposure. Chondrocytes were isolated following serial enzymatic digestion, and stained using SYTO®/DEAD Red™ (Molecular Probes, Eugene, OR). A flow cytometer was then used to detect differential cell fluorescence; size; granularity; and the number of live cells, dead cells, and post‐irradiation debris in each treatment population.

Results

Nearly 60% of chondrocytes from reshaped cartilage samples isolated shortly after one irradiation, were viable while non‐irradiated controls were 100% viable. Specimens irradiated two or three times demonstrated increasing amounts of cellular debris along with a reduction in chondrocyte viability: 31 and 16% after two and three exposures, respectively. In those samples maintained in culture medium and assayed 5 days after irradiation, viability was reduced by 28–88%, with the least amount of deterioration in untreated and singly irradiated samples.

Conclusions

Functional fluorescent dyes combined with flow cytometric analysis successfully determines the effect of laser irradiation on the viability of reshaped cartilage. Lasers Surg. Med. 32:3–9,2003. © 2003 Wiley‐Liss, Inc.
Viral induction of site‐specific chromosome damage
Authors: Fortunato Elizabeth A. , Spector Deborah H.
Published: January 2003

The advent of advanced cell culture and cytogenetics techniques in the 1950s opened a new avenue for research on the pathogenic interactions between animal viruses and their hosts. Studies of many viruses revealed their ability to nonspecifically induce cytogenetic damage to their host cell's chromosomes. However, only three viruses, the oncogenic adenoviruses, herpes simplex virus (HSV) and human cytomegalovirus (HCMV), have been found to cause non‐random, site‐specific chromosomal damage. Adenovirus (Ad) type 12 induces fragility at four distinct loci (RNU1, RNU2, RN5S and PSU1) in many different types of human cells. A common feature of these loci is that they contain a repeated array of transcriptionally active genes encoding small structural RNAs. Site‐specific induction of breaks also requires the virally encoded E1B protein of Mr 55 000 and the C‐terminus of the cellular p53 protein. Analysis of the induction of damage by HSV and HCMV necessitates consideration of several factors, including the strain of virus used, the timing of infection, the type of cell used, and the multiplicity of infection. Both HSV strains 1 and 2 are cytotoxic, although the former seems to be more proficient at inducing damage. At early times post infection, HSV induces breaks and specific uncoiling of the centromeres of chromosomes 1, 9 and 16. This is followed at later times by a more complete severing of all of the chromosomes, termed pulverisation. Damage by HSV requires viral entry and de novo viral protein synthesis, with immediate early viral proteins responsible for the induction of breaks and uncoiling and early gene products (most likely nucleases) involved in the extensive pulverisation seen later. HCMV has been studied primarily in permissive human fibroblasts. Its ability to induce specific damage in chromosome 1 at two loci, 1q21 and 1q42, was only recently revealed as the cells must be in S‐phase when they are infected for the breaks to be observed. In contrast to adenovirus and HSV, HCMV induction of specific breakage requires only viral entry into the cell and not de novo viral protein expression. This latter point may be a factor in its ability to cause damage in the developing fetal brain, where the most severe clinical manifest ations of congenital infection are observed. Copyright © 2003 John Wiley & Sons, Ltd.
The indirect effects of virus infections
Authors: Griffiths PD
Published: January 2003

An Erratum has been published for this article in Rev. Med. Virol. 2003; 13 (3): 201.

No abstract
Two‐dimensional quiet time equilibrium for the inner plasma sheet protons and magnetic field
Authors: Wang Chih‐Ping , Lyons Larry R. , Chen Margaret W. , Wolf Richard A.
Published: January 2003

In order to study the quiet time proton flow and magnetic field in the inner plasma sheet resulting from electric and magnetic drifts, we incorporate a modified version of the Magnetospheric Specification Model with a modified Tsyganenko 96 magnetic field model to self‐consistently simulate plasma sheet protons and magnetic fields with two‐dimensional force balance maintained along the midnight meridian. The resulting equatorial proton flows and pressures agree very well with observations quantitatively. Because of this agreement, the simulated force‐balanced magnetic field configuration should give more realistic plasma sheet magnetic field variations for quiet times than does the original T96 model. This 2‐D self‐consistent simulation reproduces the observed flows and pressures better than our previous 1‐D self‐consistent simulation. The improvement results from a more accurate modeling of the coupling between plasma and magnetic field in the 2‐D self‐consistent simulation.
Deep flows in the Yucatan Channel and their relation to changes in the Loop Current extension
Authors: Bunge L. , Ochoa J. , Badan A. , Candela J. , Sheinbaum J.
Published: January 2003

The first attempt to establish a relation between the Loop Current extension and deep flows in Yucatan Channel was made by Maul et al. [1985]; it was unsuccessful, probably because of the low spatial resolution of their observations. From September 8, 1999, to June 17, 2000, eight moorings with acoustic Doppler current profilers, current meters, and thermometers were deployed across the Yucatan Channel. The data from these arrays were used to compute time series of the transports below the level of the deepest isotherm observed in the Florida Straits, as required by a simple box model that restricts deep exchanges with the Gulf of Mexico to the Yucatan Channel. The surface extension of the Loop Current was inferred from 3 day advanced very high resolution radiometer imagery from October to May, when temperature gradients were sufficient to map the warm water unambiguously. The deep transports appear at first unrelated to the rate of change of the Loop Current extension, but filtering the series with a 20 day running mean increases the correlation between the low‐pass series to 0.62, and up to 0.83 with a lag of 8.5 days, with Loop Current changes leading the deep flows. The cumulative deep transport, a quantity that favors lower frequencies, is very well related (correlations >0.9) to the surface extension of the Loop Current, also with a lag of about a week. These lags are not statistically significant but suggest a timescale for internal adjustment processes in the Gulf of Mexico. The empirical orthogonal function of the current best related to the area extension of the Loop Current represents a unidirectional flow across the entire deep section, flowing either toward or from the Gulf of Mexico, and includes a strong expression of the Yucatan Undercurrent.
Using broadband erythemal UV instruments to measure relative irradiance
Authors: Nunez Manuel , Kuchinke Christopher , Gies Peter
Published: January 2003

This study examines the accuracy of the model 501A UV biometer in taking measurements relative to a predetermined background condition. The UVSPEC model with the discrete ordinates radiative transfer (DISORT) algorithm was used to mimic a range of radiation environments covering differing zenith angles, aerosol, and cloud regimes. These data were used to model typical responses for two hypothetical biometers with differing spectral and cosine responses. A ratio was then calculated between the irradiance for any zenith angle, atmospheric opacity, and ozone load and the irradiance for the same zenith angle and ozone load but for a clean atmosphere with 95‐km visibility conditions. Both virtual instruments gave very similar ratios for a wide variety of aerosol loads, cloud cover, and zenith angles. Furthermore, the instrument ratios also agreed with ratios predicted by an instrument with a perfect cosine response and responding to the erythema curve. The above theoretical results were tested with three model 501A biometers that were sampling the same environment for a three‐month period in Hobart, Australia. Ratios were calculated for each instrument between any 10‐min measured average irradiance and the instrument value predicted for the same ozone load and zenith angle but for cloudless conditions. Instrument ratios for solar zenith angles less than 70° agree closely with each other, with a coefficient of variance exceeding 0.99 and RMS errors of between 1 and 2%. Finally, the data may be turned into absolute corrected irradiance by using the UVSPEC calculations as discussed in the paper.
A case study for land model evaluation: Simulation of soil moisture amplitude damping and phase shift
Authors: Wu Wanru , Geller Marvin A. , Dickinson Robert E.
Published: January 2003

Observations have described soil moisture profile variability in terms of phase shift, fluctuation damping, and persistence increasing with soil depth [Wu et al., 2002]. This variability as a function of soil depth couples to climate variability. Whether or not land models can reproduce this variability should be a good test of their parameterizations in soil hydrology both physically and numerically. A widely used multilayer land surface model was applied to simulate the soil moisture profile variability documented from observations to explore the sensitivity to various parameters and to evaluate the model performances through the detailed analysis of a case study. Sensitivity experiments assumed changes of (1) the initial soil moisture field; (2) the root sink term; (3) the soil texture; and (4) the atmospheric forcing at upper boundary. Their impacts on the soil moisture profile phase shift, amplitude damping, and corresponding evapotranspiration were examined. The key land surface prognostic variables, i.e., soil moisture and evapotranspiration, were evaluated against observations prior to the sensitivity integrations. All the factors that affected the soil moisture profile variability of amplitude damping and phase shift also influenced the amplitude and phase of evapotranspiration, suggesting that the simulation of soil moisture profile variability might be more important in the context of timescales than the soil wetness field itself.
Timing of magnetic reconnection initiation during a global magnetospheric substorm onset
Authors: Baker D. N. , Peterson W. K. , Eriksson S. , Li X. , Blake J. B. , Burch J. L. , Daly P. W. , Dunlop M. W. , Korth A. , Donovan E. , Friedel R. , Fritz T. A. , Frey H. U. , Mende S. B. , Roeder J. , Singer H. J.
Published: January 2003

We have used a unique constellation of Earth‐orbiting spacecraft and ground‐based measurements in order to study a relatively isolated magnetospheric substorm event on August 27, 2001. Global ultraviolet images of the northern auroral region established the substorm expansion phase onset at 0408:19 (±1 min) UT. Concurrent measurements from the GOES‐8, POLAR, LANL, and CLUSTER spacecraft allow us to construct a timeline which is consistent with magnetic reconnection on the closed field lines of the central plasma sheet near XGSM ∼ −18 RE some 7 minutes prior to the near‐earth and auroral region times of substorm expansion phase onset. This suggests that magnetic reconnection (i.e., the substorm neutral line) in this case formed in the mid‐tail region substantially before current disruption, field dipolarization near geostationary orbit, or auroral substorm onsets occurred. Thus, the magnetic reconnection process is interpreted as the causative driver of dissipation in this well‐observed case.
X‐ray observations of MeV electron precipitation with a balloon‐borne germanium spectrometer
Authors: Millan R. M. , Lin R. P. , Smith D. M. , Lorentzen K. R. , McCarthy M. P.
Published: January 2003

The high‐resolution germanium detector aboard the MAXIS (MeV Auroral X‐ray Imaging and Spectroscopy) balloon payload detected nine X‐ray bursts with significant flux extending above 0.5 MeV during an 18 day flight over Antarctica. These minutes‐to‐hours‐long events are characterized by an extremely flat spectrum (∼E−2) similar to the first MeV event discovered in 1996, indicating that the bulk of parent precipitating electrons is at relativistic energies. The MeV bursts were detected between magnetic latitudes 58°–68° (L‐values of 3.8–6.7) but only in the late afternoon/dusk sectors (14:30–00:00 MLT), suggesting scattering by EMIC (electromagnetic ion cyclotron) waves as a precipitation mechanism. We estimate the average flux of precipitating E ≥ 0.5 MeV electrons to be ∼360 cm−2s−1, corresponding to about 5 × 1025 such electrons precipitated during the eight days at L = 3.8–6.7, compared to ∼2 × 1025 trapped 0.5–3.6 MeV electrons estimated from dosimeter measurements on a GPS spacecraft. These observations show that MeV electron precipitation events are a primary loss mechanism for outer zone relativistic electrons.
Energy and depth of Usu 2000 phreatic explosions
Authors: Yokoo Akihiko , Taniguchi Hiromitsu , Goto Akio , Oshima Hiromitsu
Published: January 2003

On 31 March 2000, the Usu volcano located in Hokkaido, Japan began erupting after 22 years of dormancy. After the first phreato‐magmatic explosion, there were many small‐scale phreatic explosions at the Nishiyama and Kompirayama Craters. In April and May, observations were made using a piezo blast‐sensor and a visible video recorder to get a better understanding of volcanic explosions. The data thus obtained were analyzed using the scaling‐laws that relate surface phenomena to both explosion energy and depth. The analysis using the shape of the explosion‐cloud and the peak over‐pressure of the volcanic blast‐wave indicated that the average explosion energy and depth of the phreatic explosions of mid‐April ranged from 1010 to 1012 J and originated from between just beneath the ground surface to a depth of a few tens of meters.
Real‐time earthquake warning by using broadband P Waveform
Authors: Tsuboi S. , Saito M. , Kikuchi M.
Published: January 2003

We develop a system, which enables an early warning of earthquake occurrence several seconds before large ground shaking begins. We assume that the vertical displacement of the broadband P waveform can be considered as the far‐field source time function of the earthquake. Based upon the seismic moment to source duration relation, we may issue an early warning that an earthquake with magnitude greater than 6 has occurred, when the initial P‐wave pulse duration continues for more than 3 seconds. We have applied this algorithm to broadband seismograms recorded at Japanese broadband stations for recent large earthquakes in Japan. We found that it really is possible to assess the occurrence of earthquakes with magnitude greater than 6 within 3 seconds after the P‐wave arrival.
Relaxation oscillators in concert: A framework for climate change at millennial timescales during the late Pleistocene
Authors: Schulz Michael , Paul André , Timmermann Axel
Published: January 2003

Using a box model of the North Atlantic Ocean and a parameterization of Heinrich Events, we suggest that self‐sustained oscillations of the large‐scale oceanic circulation provide a framework to accommodate crucial elements of late Pleistocene climate variability: (i) Dansgaard‐Oeschger‐style oscillations with varying interstadial length, (ii) synchronization between Dansgaard‐Oeschger stadials and Heinrich Events, and (iii) Younger Dryas‐type events. The latter result from the restart of the oscillations after a glacial maximum and can be regarded as Dansgaard‐Oeschger stadials, overprinted by rapidly changing boundary conditions.
Time‐variable gravity signal during the water impoundment of China's Three‐Gorges Reservoir
Authors: Boy Jean‐Paul , Chao Benjamin F.
Published: January 2003

Beginning in 2003, China's Three‐Gorges Reservoir will start water impoundment in phases. By 2009, it will be holding 40 km3 of water, flooding a stretch of middle Yangtze River about 600 km in length. The water impoundment process represents a geophysical “controlled experiment” offering a unique opportunity for detailed studies of a classical forward/inverse modeling problem of surface loading. While Wang [2000] studied the large loading effects on a local scale, we aim for longer spatial scales upwards from several hundred km, specially on the time‐variable gravity signals that can be detected by the newly‐launched GRACE satellite mission, whose 5‐year lifetime (until 2007) will span the major impoundment period. Our results using the Green's function method adopting the PREM elastic Earth model indicate that the per‐year geoid height increase is above the GRACE observational sensitivity out to harmonic degree 20, and to degree 50 (corresponding to a wavelength of 800 km) when integrated over the 5‐year period.
Cloud activation of single‐component organic aerosol particles
Authors: Raymond Timothy M. , Pandis Spyros N.
Published: January 2003

The organic fraction of ambient aerosols is a complex mixture of hundreds of organic compounds varying in chemical structure and physical properties. The cloud condensation nuclei (CCN) activities of single‐component organic particles were experimentally investigated. Activation diameters were determined using a Tandem Differential Mobility Analyzer and a thermal diffusion Cloud Condensation Nucleus Counter. Studies were performed at supersaturations of 0.3 and 1% with dry particle diameters ranging between 0.02 and 0.2 μm. The focus was on both hygroscopic secondary organics and hydrophobic primary organics. Laboratory experiments were performed with sodium chloride, ammonium sulfate, glutaric acid, adipic acid, pinonic acid, glutamic acid, leucine, cholesterol, pinic acid, norpinic acid, hexadecane, hexadecanol, myristic acid, palmitic acid, and stearic acid. The results were compared with the classical Köhler theory and a theory that accounts for the limited solubility of many organics. It was discovered that organic species with bulk solubilities in water less than 0.01 g cm−3 can be a good source of CCN in the atmosphere if their contact angles with water are zero. Experiments confirmed that Köhler theory works well in predicting activation of soluble inorganic species and organics that are wettable by water, while an extension of the theory appears necessary to account for the low‐solubility organic species that are not wettable by water.
Variability of the Arctic atmospheric moisture budget from TOVS satellite data
Authors: Groves David G. , Francis Jennifer A.
Published: January 2003

Temporal and spatial variability of the Arctic atmospheric moisture budget is investigated using a new 19‐year data set (1980 to 1998) produced from daily precipitable water retrieved from the TIROS Operational Vertical Sounder (TOVS) and upper‐level winds from the NCEP‐NCAR Reanalysis. A companion paper describes the creation and validation of these new moisture budget products [Groves and Francis, 2002]. Seasonal differences in moisture transport arise from distinct winter/summer circulation regimes and meridional moisture gradients. In winter, approximately 80% of the net precipitation (precipitation minus evaporation, P‐E) is transported along well‐defined storm tracks. Summer P‐E is double that of winter and dominates the annual pattern. Decadal differences in winter P‐E reveal statistically significant increases in the Beaufort and eastern Greenland‐Iceland‐Norwegian Seas, decreases in the Canadian Archipelago (islands in far northeast Canada) and Kara Sea, and a slight increase in the Arctic as a whole. Annual differences are dominated by winter changes. When the phase of the Arctic Oscillation (AO) index is positive, the net PW flux across 70°N in winter is 6 times larger than on negative‐index days. Over the entire Arctic, P‐E is 29% larger (20% lower) than the average on days with a positive (negative) AO index. In summer the PW transport is twice as large, and P‐E is 27% higher on positive versus negative AO days. These results suggest that if the AO continues its trend toward a predominantly positive phase, we should expect to observe increasing precipitation in the Arctic overall, and particularly in regions adjacent to the marginal ice zones.
Low-density lipoprotein receptor-related protein 5 (LRP5) is essential for normal cholesterol metabolism and glucose-induced insulin secretion
Authors: Fujino Takahiro , Asaba Hiroshi , Kang Man-Jong , Ikeda Yukio , Sone Hideyuki , Takada Shinji , Kim Dong-Ho , Ioka Ryoichi X. , Ono Masao , Tomoyori Hiroko , Okubo Minoru , Murase Toshio , Kamataki Akihisa , Yamamoto Joji , Magoori Kenta , Takahashi Sadao , Miyamoto Yoshiharu , Oishi Hisashi , Nose Masato , Okazaki Mitsuyo , Usui Shinichi , Imaizumi Katsumi , Yanagisawa Masashi , Sakai Juro , Yamamoto Tokuo T.
Published: January 2003

A Wnt coreceptor low-density lipoprotein receptor-related protein 5 (LRP5) plays an essential role in bone accrual and eye development. Here, we show that LRP5 is also required for normal cholesterol and glucose metabolism. The production of mice lacking LRP5 revealed that LRP5 deficiency led to increased plasma cholesterol levels in mice fed a high-fat diet, because of the decreased hepatic clearance of chylomicron remnants. In addition, when fed a normal diet, LRP5-deficient mice showed a markedly impaired glucose tolerance. The LRP5-deficient islets had a marked reduction in the levels of intracellular ATP and Ca
2+
in response to glucose, and thereby glucose-induced insulin secretion was decreased. The intracellular inositol 1,4,5-trisphosphate (IP3) production in response to glucose was also reduced in LRP5−/− islets. Real-time PCR analysis revealed a marked reduction of various transcripts for genes involved in glucose sensing in LRP5−/− islets. Furthermore, exposure of LRP5+/+ islets to Wnt-3a and Wnt-5a stimulates glucose-induced insulin secretion and this stimulation was blocked by the addition of a soluble form of Wnt receptor, secreted Frizzled-related protein-1. In contrast, LRP5-deficient islets lacked the Wnt-3a-stimulated insulin secretion. These data suggest that Wnt/LRP5 signaling contributes to the glucose-induced insulin secretion in the islets.
Structural basis and prediction of substrate specificity in protein serine/threonine kinases
Authors: Brinkworth Ross I. , Breinl Robert A. , Kobe Bostjan
Published: January 2003

The large number of protein kinases makes it impractical to determine their specificities and substrates experimentally. Using the available crystal structures, molecular modeling, and sequence analyses of kinases and substrates, we developed a set of rules governing the binding of a heptapeptide substrate motif (surrounding the phosphorylation site) to the kinase and implemented these rules in a web-interfaced program for automated prediction of optimal substrate peptides, taking only the amino acid sequence of a protein kinase as input. We show the utility of the method by analyzing yeast cell cycle control and DNA damage checkpoint pathways. Our method is the only available predictive method generally applicable for identifying possible substrate proteins for protein serine/threonine kinases and helpsin silicoconstruction of signaling pathways. The accuracy of prediction is comparable to the accuracy of data from systematic large-scale experimental approaches.
The role of neutralizing antibodies for mouse mammary tumor virus transmission and mammary cancer development
Authors: Finke Daniela , Luther Sanjiv A. , Acha-Orbea Hans
Published: January 2003

Mouse mammary tumor virus (MMTV) infection establishes chronic germinal centers and a lifelong neutralizing Ab response. We show that removal of the draining lymph node after establishment of the germinal center reaction led to complete loss of neutralizing Abs despite comparable infection levels in peripheral lymphocytes. Importantly, in the absence of neutralization, only the exocrine organs mammary gland, salivary gland, pancreas, and skin showed strikingly increased infection, resulting in accelerated mammary tumor development. Induction of stronger neutralization did not influence chronic infection levels of peripheral lymphoid organs but strongly inhibited mammary gland infection and virus transmission to the next generation. Taken together, we provide evidence that a tight equilibrium in virus neutralization allows limited infection of exocrine organs and controls cancer development in susceptible mouse strains. These experiments show that a strong neutralizing Ab response induced after infection is not able to control lymphoid MMTV infection. Strong neutralization, however, is capable of blocking amplification of mammary gland infection, tumor development, and virus transmission to the next generation. The results also indicate a role of neutralization in natural resistance to MMTV infection.
Protein-facilitated base flipping in DNA by cytosine-5-methyltransferase
Authors: Huang Niu , Banavali Nilesh K. , MacKerell Alexander D.
Published: January 2003

DNA methylation, various DNA repair mechanisms, and possibly early events in the opening of DNA as required for transcription and replication are initiated by flipping of a DNA base out of the DNA double helix. The energetics and structural mechanism of base flipping in the presence of the DNA-processing enzyme, cytosine 5-methyltransferase from
Hha
I (M.
Hha
I), were obtained through molecular dynamics based upon free-energy calculations. Free-energy profiles for base flipping show that, when in the closed conformation, M.
Hha
I lowers the free-energy barrier to flipping by 17 kcal/mol and stabilizes the fully flipped state. Flipping is shown to occur via the major groove of the DNA. Structural analysis indicates that flipping is facilitated by destabilization of the DNA double-helical structure and substitution of DNA base-pairing and base-stacking interactions with DNA–protein interactions. The fully flipped state is stabilized by DNA–protein interactions that are enhanced upon binding of coenzyme. This study represents an atomic detail description of the mechanism by which a protein facilitates specific structural distortion in DNA.
Crystal structure of oxygen-evolving photosystem II fromThermosynechococcus vulcanusat 3.7-Å resolution
Authors: Kamiya Nobuo , Shen Jian-Ren
Published: January 2003

Photosystem II (PSII) is a multisubunit membrane protein complex performing light-induced electron transfer and water-splitting reactions, leading to the formation of molecular oxygen. The first crystal structure of PSII from a thermophilic cyanobacteriumThermosynechococcus elongatuswas reported recently [Zouni, A., Witt, H. T., Kern, J., Fromme, P., Krauss, N., Saenger, W. & Orth, P. (2001)Nature409, 739–743)] at 3.8-Å resolution. To analyze the PSII structure in more detail, we have obtained the crystal structure of PSII from another thermophilic cyanobacterium,Thermosynechococcus vulcanus, at 3.7-Å resolution. The present structure was built on the basis of the sequences of PSII large subunits D1, D2, CP47, and CP43; extrinsic 33- and 12-kDa proteins and cytochromec550; and several low molecular mass subunits, among which the structure of the 12-kDa protein was not reported previously. This yielded much information concerning the molecular interactions within this large protein complex. We also show the arrangement of chlorophylls and cofactors, including two β-carotenes recently identified in a region close to the reaction center, which provided important clues to the secondary electron transfer pathways around the reaction center. Furthermore, possible ligands for the Mn-cluster were determined. In particular, the C terminus of D1 polypeptide was shown to be connected to the Mn cluster directly. The structural information obtained here provides important insights into the mechanism of PSII reactions.
Identification of an intracellular receptor for lysophosphatidic acid (LPA): LPA is a transcellular PPARγ agonist
Authors: McIntyre Thomas M. , Pontsler Aaron V. , Silva Adriana R. , St. Hilaire Andy , Xu Yong , Hinshaw Jerald C. , Zimmerman Guy A. , Hama Kotaro , Aoki Junken , Arai Hiroyuki , Prestwich Glenn D.
Published: January 2003

Lysophosphatidic acid (LPA) is a pluripotent lipid mediator acting through plasma membrane-associated LPAxreceptors that transduce many, but not all, of its effects. We identify peroxisome proliferator-activated receptor γ (PPARγ) as an intracellular receptor for LPA. The transcription factor PPARγ is activated by several lipid ligands, but agonists derived from physiologic signaling pathways are unknown. We show that LPA, but not its precursor phosphatidic acid, displaces the drug rosiglitazone from the ligand-binding pocket of PPARγ. LPA and novel LPA analogs we made stimulated expression of a PPAR-responsive element reporter and the endogenous PPARγ-controlled gene CD36, and induced monocyte lipid accumulation from oxidized low-density lipoprotein via the CD36 scavenger receptor. The synthetic LPA analogs were effective PPARγ agonists, but were poor ones for LPA1, LPA2, or LPA3receptor transfected cells. Transfection studies in yeast, which lack nuclear hormone and LPAxreceptors, show that LPA directly activates PPARγ. A major growth factor of serum is LPA generated by thrombin-activated platelets, and media from activated platelets stimulated PPARγ function in transfected RAW264.7 macrophages. This function was suppressed by ectopic LPA-acyltransferase expression. LPA is a physiologic PPARγ ligand, placing PPARγ in a signaling pathway, and PPARγ is the first intracellular receptor identified for LPA. Moreover, LPA produced by stimulated plasma platelets activates PPARγ in nucleated cells.
Evidence for the widespread coupling of alternative splicing and nonsense-mediated mRNA decay in humans
Authors: Lewis Benjamin P. , Green Richard E. , Brenner Steven E.
Published: January 2003

To better understand the role of alternative splicing, we conducted a large-scale analysis of reliable alternative isoforms of known human genes. Each isoform was classified according to its splice pattern and supporting evidence. We found that one-third of the alternative transcripts examined contain premature termination codons, and most persist even after rigorous filtering by multiple methods. These transcripts are apparent targets of nonsense-mediated mRNA decay (NMD), a surveillance mechanism that selectively degrades nonsense mRNAs. Several of these transcripts are from genes for which alternative splicing is known to regulate protein expression by generating alternate isoforms that are differentially subjected to NMD. We propose that regulated unproductive splicing and translation (RUST), through the coupling of alternative splicing and NMD, may be a pervasive, underappreciated means of regulating protein expression.
Somatostatin receptor subtype 2 sensitizes human pancreatic cancer cells to death ligand-induced apoptosis
Authors: Guillermet Julie , Saint-Laurent Nathalie , Rochaix Philippe , Cuvillier Olivier , Levade Thierry , Schally Andrew V. , Pradayrol Lucien , Buscail Louis , Susini Christiane , Bousquet Corinne
Published: January 2003

Somatostatin receptor subtype 2 (sst2) gene expression is lost in 90% of human pancreatic adenocarcinomas. We previously demonstrated that stable sst2 transfection of human pancreatic BxPC-3 cells, which do not endogenously express sst2, inhibits cell proliferation, tumorigenicity, and metastasis. These sst2 effects occur as a consequence of an autocrine sst2-dependent loop, whereby sst2 induces expression of its own ligand, somatostatin. Here we investigated whether sst2 induces apoptosis in sst2-transfected BxPC-3 cells. Expression of sst2 induced a 4.4- ± 0.05-fold stimulation of apoptosis in BxPC-3 through the activation of tyrosine phosphatase SHP-1. sst2 also sensitized these cells to apoptosis induced by tumor necrosis factor α (TNFα), enhancing it 4.1- ± 1.5-fold. Apoptosis in BxPC-3 cells mediated by TNF-related apoptosis-inducing ligand (TRAIL) and CD95L was likewise increased 2.3- ± 0.5-fold and 7.4- ± 2.5-fold, respectively. sst2-dependent activation and cell sensitization to death ligand-induced apoptosis involved activation of the executioner caspases, key factors in both death ligand- or mitochondria-mediated apoptosis. sst2 affected both pathways: first, by up-regulating expression of TRAIL and TNFα receptors, DR4 and TNFRI, respectively, and sensitizing the cells to death ligand-induced initiator capase-8 activation, and, second, by down-regulating expression of the antiapoptotic mitochondrial Bcl-2 protein. These results are of interest for the clinical management of chemoresistant pancreatic adenocarcinoma by using a combined gene therapy based on the cotransfer of genes for both the sst2 and a nontoxic death ligand.