bluuebunny/crossref_metadata_2025 huggingface dataset:
Substrate Specificity of the Nonribosomal Peptide Synthetase PvdD fromPseudomonas aeruginosa
Authors: Ackerley David F. , Caradoc-Davies Tom T. , Lamont Iain L.
Published: April 2003

Pseudomonas aeruginosaPAO1 secretes a siderophore, pyoverdinePAO, which contains a short peptide attached to a dihydroxyquinoline moiety. Synthesis of this peptide is thought to be catalyzed by nonribosomal peptide synthetases, one of which is encoded by thepvdDgene. The first module ofpvdDwas overexpressed inEscherichia coli, and the protein product was purified.l-Threonine, one of the amino acid residues in pyoverdinePAO, was an effective substrate for the recombinant protein in ATP-PPiexchange assays, showing that PvdD has peptide synthetase activity. Other amino acids, includingd-threonine,l-serine, andl-allo-threonine, were not effective substrates, indicating that PvdD has a high degree of substrate specificity. A three-dimensional modeling approach enabled us to identify amino acids that are likely to be critical in determining the substrate specificity of PvdD and to explore the likely basis of the high substrate selectivity. The approach described here may be useful for analysis of other peptide synthetases.
IS
6110
-Mediated Deletion Polymorphism in the Direct Repeat Region of Clinical Isolates of
Mycobacterium tuberculosis
Authors: Sampson S. L. , Warren R. M. , Richardson M. , Victor T. C. , Jordaan A. M. , van der Spuy G. D. , van Helden P. D.
Published: April 2003

This study investigates the phenomenon of IS
6110
-mediated deletion polymorphism in the direct repeat (DR) region of the genome of
Mycobacterium tuberculosis
. Clinical isolates and their putative predecessors were compared using a combination of DR region restriction fragment length polymorphism, IS
6110
DNA fingerprinting, spoligotyping, and DNA sequencing, which allowed the mapping of chromosome structure and deletion junctions. The data suggest that adjacently situated IS
6110
elements mediate genome deletion. However, in contrast to previous reports, deletions appear to be mediated by inversely oriented IS
6110
elements. This suggests that these events may occur via mechanisms other than RecA-mediated homologous recombination. The results underscore the important role of IS
6110
-associated deletion hypervariability in driving
M. tuberculosis
genome evolution.
Agrobacterium tumefaciensVirB6 Protein Participates in Formation of VirB7 and VirB9 Complexes Required for Type IV Secretion
Authors: Jakubowski Simon J. , Krishnamoorthy Vidhya , Christie Peter J.
Published: April 2003

This study characterized the contribution ofAgrobacterium tumefaciensVirB6, a polytopic inner membrane protein, to the formation of outer membrane VirB7 lipoprotein and VirB9 protein multimers required for type IV secretion. VirB7 assembles as a disulfide cross-linked homodimer that associates with the T pilus and a VirB7-VirB9 heterodimer that stabilizes other VirB proteins during biogenesis of the secretion machine. Two presumptive VirB protein complexes, composed of VirB6, VirB7, and VirB9 and of VirB7, VirB9, and VirB10, were isolated by immunoprecipitation or glutathioneS-transferase pulldown assays from detergent-solubilized membrane extracts of wild-type A348 and a strain producing only VirB6 through VirB10 among the VirB proteins. To examine the biological importance of VirB6 complex formation for type IV secretion, we monitored the effects of nonstoichiometric VirB6 production and the synthesis of VirB6 derivatives with 4-residue insertions (VirB6.i4) on VirB7 and VirB9 multimerization, T-pilus assembly, and substrate transfer. AvirB6gene deletion mutant accumulated VirB7 dimers at diminished steady-state levels, whereas complementation with a plasmid bearing wild-typevirB6partially restored accumulation of the dimers. VirB6 overproduction was correlated with formation of higher-order VirB9 complexes or aggregates and also blocked substrate transfer without a detectable disruption of T-pilus production; these phenotypes were displayed by cells grown at 28°C, a temperature that favors VirB protein turnover, but not by cells grown at 20°C. Strains producing several VirB6.i4 mutant proteins assembled novel VirB7 and VirB9 complexes detectable by nonreducing sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and two strains producing the D60.i4 and L191.i4 mutant proteins translocated IncQ plasmid and VirE2 effector protein substrates in the absence of a detectable T pilus. Our findings support a model that VirB6 mediates formation of VirB7 and VirB9 complexes required for biogenesis of the T pilus and the secretion channel.
Atypical 16S rRNA Gene Copies in
Ochrobactrum intermedium
Strains Reveal a Large Genomic Rearrangement by Recombination between
rrn
Copies
Authors: Teyssier Corinne , Marchandin Hélène , Siméon De Buochberg Michèle , Ramuz Michel , Jumas-Bilak Estelle
Published: April 2003

Ochrobactrum intermedium
is an opportunistic human pathogen belonging to the alpha 2 subgroup of proteobacteria. The 16S rDNA sequences of nine
O. intermedium
isolates from a collection of clinical and environmental isolates exhibited a 46-bp insertion at position 187, which was present in only one sequence among the 82 complete or partial 16S rDNA sequences of
Ochrobactrum
spp. available in data banks. Reverse transcription-PCR experiments showed that the 46-bp insertion remained in the 16S rRNA. The inserted sequence folded into a stem-loop structure, which took place in and prolonged helix H184 of the 16S rRNA molecule. Helix H184 has been described as conserved in length among eubacteria, suggesting the idiosyncratic character of the 46-bp insertion. Pulsed-field gel electrophoresis experiments showed that seven of the clinical isolates carrying the 46-bp insertion belonged to the same clone. Insertion and
rrn
copy numbers were determined by hybridization and I-
Ceu
I digestion. In the set of clonal isolates, the loss of two insertion copies revealed the deletion of a large genomic fragment of 150 kb, which included one
rrn
copy; deletion occurred during the in vivo evolution of the clone. Determination of the
rrn
skeleton suggested that the large genomic rearrangement occurred during events involving homologous recombination between
rrn
copies. The loss of insertion copies suggested a phenomenon of concerted evolution among heterogeneous
rrn
copies.
Nitrogen Regulation of the
codBA
(Cytosine Deaminase) Operon from
Escherichia coli
by the Nitrogen Assimilation Control Protein, NAC
Authors: Muse Wilson B. , Rosario Christopher J. , Bender Robert A.
Published: April 2003

Transcription of the cytosine deaminase (
codBA
) operon of
Escherichia coli
is regulated by nitrogen, with about three times more
codBA
expression in cells grown in nitrogen-limiting medium than in nitrogen-excess medium. β-Galactosidase expression from
codBp-lacZ
operon fusions showed that the nitrogen assimilation control protein NAC was necessary for this regulation. In vitro transcription from the
codBA
promoter with purified RNA polymerase was stimulated by the addition of purified NAC, confirming that no other factors are required. Gel mobility shifts and DNase I footprints showed that NAC binds to a site centered at position −59 relative to the start site of transcription and that mutants that cannot bind NAC there cannot activate transcription. When a longer promoter region (positions −120 to +67) was used, a double footprint was seen with a second 26-bp footprint separated from the first by a hypersensitive site. When a shorter fragment was used (positions −83 to +67), only the primary footprint was seen. Nevertheless, both the shorter and longer fragments showed NAC-mediated regulation in vivo. Cytosine deaminase expression in
Klebsiella pneumoniae
was also regulated by nitrogen in a NAC-dependent manner.
K. pneumoniae
differs from
E. coli
in having two cytosine deaminase genes, an intervening open reading frame between the
codB
and
codA
orthologs, and a different response to hypoxanthine which increased
cod
expression in
K. pneumoniae
but decreased it in
E. coli
.
Essentiality of
clpX
, but Not
clpP
,
clpL
,
clpC
, or
clpE
, in
Streptococcus pneumoniae
R6
Authors: Robertson Gregory T. , Ng Wai-Leung , Gilmour Raymond , Winkler Malcolm E.
Published: April 2003

We show by using a regulated promoter that
clpX
of
Streptococcus pneumoniae
R6 is essential, whereas
clpP
,
clpL
,
clpC
, and
clpE
can be disrupted. The essentiality of
clpX
was initially missed because of duplication and rearrangement in the region of the chromosome containing
clpX
. Depletion of ClpX resulted in a rapid loss of viability without overt changes in cell morphology. Essentiality of
clpX
, but not
clpP
, has not been reported previously.
Isolation of a New Hemimethylated DNA Binding Protein Which Regulates
dnaA
Gene Expression
Authors: d'Alençon Emmanuelle , Taghbalout Aziz , Bristow Claire , Kern Renée , Aflalo Revital , Kohiyama Masamichi
Published: April 2003

In this report, we show that
yccV
, a gene of unknown function, encodes a protein having an affinity for a hemimethylated
oriC
DNA and that the protein negatively controls
dnaA
gene expression in vivo.
GABITOV–TURITSYN EQUATION FOR SOLITONS IN OPTICAL FIBERS
Authors: BISWAS ANJAN
Published: April 2003

The dynamics of optical solitons with dispersion-management propagating through optical fibers with damping and amplification is studied. A multiple-scale perturbation expansion method is used to analyze the nonlinear Schrödinger's equation that governs the propagation of such solitons. In this paper we have considered both polarization preserving as well as birefringent fibers. Finally, the case of dense wavelength-division-multiplexed soliton system is also considered.
DISPERSION-MANAGED SOLITONS IN OPTICAL COUPLERS
Authors: BISWAS ANJAN
Published: April 2003

The soliton perturbation theory is employed to study chirped solitons that propagate through optical couplers and is governed by the dispersion-managed nonlinear Schrödinger's equation. Here, in this paper, we have considered both kinds of couplers namely twin-core as well as the multiple-core type. In either case, both Gaussian and super-Gaussian solitons are taken into account.
INVESTIGATION OF NEAR TWO-PHOTON RESONANCE OPTICAL NONLINEARITIES IN Ni(Ac)2[N-(8-QUINOLYL) PYRIDINE-2-CARBOXAMIDE] · 4H2O BY THE Z-SCAN TECHNIQUE
Authors: GUO SHENG-LI , WANG HUI-TIAN , MING N. B. , ZHANG JUN-YONG , GUO ZHI-JIAN
Published: April 2003

We describe a modified Z-scan technique for the case when nonlinear refraction is accompanied by nonlinear absorption to separately evaluate the nonlinear refraction and the nonlinear absorption by performing straightforward measurements with the aperture removed. We divide the closed aperture (S < 1) normalized Z-scan by a scan with an open aperture (S = 1). With nanosecond scale at a 532 nm wavelength, we first measured the nonlinear optical absorption and refraction coefficients of a solution of Ni(Ac)2[N-(8-quinolyl) pyridine-2-carboxamide] · 4H2O by using the modified Z-scan technique. The nonlinear absorption originates from the near resonant two-photon absorption while the mechanism of the nonlinear refraction is the near resonant two-photon absorption transition enhancement. The linear increasing dependences of the optical nonlinearities on the incident irradiance arise from the population redistribution due to the near resonant two-photon absorption.
STUDY ON PHOTOBLEACHING OF METHYLENE BLUE DOPED IN PMMA, PVA AND GELATIN USING PHOTOACOUSTIC TECHNIQUE
Authors: MAHMOOD MAT YUNUS W. , CHAN KOK SHENG , ZIN WAN YUNUS WAN MD.
Published: April 2003

The photobleaching of Methylene blue embedded in the solid matrix PMMA (poly(methylmethacrylate)), PVA (poly(vinyl alcohol)) and gelatin has been investigated using a photoacoustic technique. Photoacoustic signals were measured as a function of time, chopping frequency, and the beam power. Experimental results indicate that the photobleaching rate is proportional to the incident laser power (260–300 mW) and decreased with increasing the concentration of dopant molecules. Methylene blue embedded in PVA shows the highest photobleaching rate then followed by gelatin and PMMA. The increase of photobleaching rate in PVA is also noticed when the beam power is increased. The thermal diffusivity values obtained for bleached PMMA, PVA and gelatin are 1.46 × 10-3 cm2/s , 0.83 × 10-3, cm2/s and 1.10 × 10-3 cm2/s respectively. Spectrophotometer and Raman spectroscopy were used to confirm the photoacoustic results.
NONLINEAR OPTICAL DEVICES: PROPERTIES OF POLYANILINE BASED CONDUCTING POLYMERS
Authors: SHARMA SUDHIR KUMAR , MISRA S. C. K. , TRIPATHI K. N.
Published: April 2003

We report on the investigation of a series of polyaniline based conducting polymers with rather different backbone structure and energy gap in order to explore the effect of their molecular architecture on nonlinear optical properties. In particular, we report on the dispersion of x(3)(-ω;ω, -ω, ω) in the spectral range covering the rising slope of the optical absorption as well as in off resonance conditions.
DISPLACEMENT AND DEFLECTION OF OPTICAL BEAMS BY NONLINEAR PLANAR WAVEGUIDE
Authors: KONAR S. , BARHAI P. K. , MEDHEKAR SARANG
Published: April 2003

In this paper we investigate the propagation characteristics of an end fired Gaussian optical beam through a planar nonlinear waveguide. Using variational formalism we have derived three coupled second order dynamical equations for the beam widths and centre of gravity of the propagating optical beam. Using these equations, we have investigated numerically the beam deflection, displacement and their possible control by nonlinearity. We have shown that intensity dependent control is possible only when the waveguide core possesses nonlinearity and the substrate is linear. In addition, we have demonstrated that such control is not possible in bulk media. We have further established that setting an appropriate length of the waveguide one can achieve maximum displacement with minimum deflection or minimum displacement with maximum deflection. Possible application of our investigation in optical communication and signal processing are highlighted.
A Simple, Effective, and Selective Synthesis Route without Template Effect (Part II) for [2 + 2] Difunctional 28-Membered Macrocyclic Ethers Based on Benzoxazine Dimers and Its Inclusion Phenomena with Metal Ions
Authors: Chirachanchai Suwabun , Phongtamrug Suttinun , Laobuthee Apirat
Published: April 2003

A macrocyclic ether produced from benzoxazine dimers and ditosylated diethylene glycols is a model to show that the cyclization occurs when intramolecular hydrogen bond of benzoxazine dimer is eliminated in the strong basic condition via a selective [2 + 2] pathway without metal template effect. Macrocyclic ethers perform inclusion phenomena at host-guest stoichiometric ratios of 1:1, and 2:1 depending on the type of metal ion, as clarified by UV and 1H NMR.
Catalytic and β-Stereoselective Mannosylation of Several Glycosyl Acceptors with Mannosyl 6-Nitro-2-benzothiazoate
Authors: Hashihayata Takashi , Mandai Hiroki , Mukaiyama Teruaki
Published: April 2003

Mannosylation of several glycosyl acceptors with a novel mannosyl donor having the 6-nitro-2-benzothiazoate function at an anomeric position proceeded smoothly in the presence of a catalytic amount of tetrakis(pentafluorophenyl)boric acid [HB(C6F5)4] to afford the corresponding disaccharides in high yields with good to high β-stereoselectivities.
Preparation of Layered Li[Ni1/2Mn1/2]O2 by Ultrasonic Spray Pyrolysis Method
Authors: Park S H , Kang S K , Kang Y C , Lee Y S , Sun Y K
Published: April 2003

Li[Ni1/2Mn1/2]O2 material was synthesized by ultrasonic spray pyrolysis method. Li[Ni1/2Mn1/2]O2 was characterized by means of X-ray diffraction, charge/discharge cycling, and cyclic voltammetry. The discharge capacities of Li/Li[Ni1/2Mn1/2]O2 cell at 30 and 55 °C slowly decreased with cycling and remained at 166 and 175 mAh/g after 50 cycles, which are 99 and 94% of initial capacities, respectively. The cyclic voltammogram studies of the Li[Ni1/2Mn1/2]O2 electrode showed only one redox peak. This phenomenon might be related to the initial activation process and/or stabilization of Li[Ni1/2Mn1/2]O2 electrode.
Telemedicine and neurosurgery: experience of a regional unit based in South Africa
Authors: Jithoo R , Govender P V , Corr P , Nathoo N
Published: April 2003

We carried out a retrospective analysis of all emergency referrals to the neurosurgery department of the Wentworth Hospital from 1996 to 1999. The hospital provided a service to seven peripheral hospitals with computerized tomography (CT) scanners and 46 hospitals without, in the province of KwaZulu Natal. By the end of the study, six of the hospitals with CT scanners had facilities for teleradiology and the mean patient return rate had fallen to 17%. In comparison, almost half the patients seen from the hospitals with no CT scanners were returned to hospital after assessment at the Wentworth Hospital. We also carried out a prospective analysis of 100 consecutive teleradiology-assisted consultations from January to March 2000. Of the 57 patients (79%) who remained at their referral hospitals, 45 had a good outcome, while the other 12 (21%) patients had a poor outcome. The implementation of teleradiology-assisted consultation decreased the number of inappropriate inter-hospital transfers while maintaining appropriate patient care and improving outcome.
Evaluation of a telemedicine demonstration project in the Magdalene Islands
Authors: Fortin Jean-Paul , Gagnon Marie-Pierre , Cloutier Alain , Labbé Françoise
Published: April 2003

The Magdalene Islands are an archipelago located in the middle of the Gulf of St Lawrence, more than 1000 km away from supra-regional medical referral centres. We have implemented and evaluated a telemedicine network for the local hospital on the Magdalene Islands. During a 13-month study period, 118 transmissions were made. Orthopaedics and radiology were the medical specialties that used telemedicine most frequently. Store-and-forward imaging was the technique used most often because of the large number of transmissions in orthopaedics and radiology. Various medical specialties and psychosocial services used videoconferencing, while realtime imaging (ultrasound) was used in gynaecology and obstetrics. A combination of videoconferencing and imaging was used for otolaryngology. A total of 101 individual patients benefited from a teleconsultation during the study period. Eight emergency transfers were avoided and 15 patients who would have required elective transfer were managed locally by telemedicine. For health-care providers, telemedicine seemed to be an acceptable way of delivering specialized services. Nevertheless, demonstration projects in telemedicine are quite different to 'real life' telemedicine utilization. Deployment of telemedicine in the health-care system as a whole will require a more structured approach.
Introducing videoconferencing into educational oncopathology seminars: technical aspects, user satisfaction and open issues
Authors: Della Mea Vincenzo , Carbone Antonino , Greatti Ermes , Beltrami Carlo A
Published: April 2003

We used set-top videoconferencing equipment connected by ISDN at 384 kbit/s for six educational seminars held between the University of Udine (the local site) and the National Cancer Institute in Aviano (the remote site), 60 km away. User satisfaction was evaluated by questionnaire. The median length of seminars was 58 min (range 48–61 min), followed by a 20 min (15–26 min) discussion. Eighty-two users answered the questionnaire (a 43% response rate): 56 in Udine (a median of 11 per seminar) and 26 in Aviano (a median of 5 per seminar). Answers to the questions were similar at the two sites. Videoconferencing did not affect the users' experience of attending the seminars, as both interest and clarity were similar at the local and remote site. The results suggested that videoconferencing is a viable method for delivering seminars in oncopathology, where image quality is important.
The Pentalfa project. 1: The development of distance continuing medical education via videoconferencing in the Dutch-speaking region of Belgium
Authors: Himpens B
Published: April 2003

A distance continuing medical education programme was established at the Katholieke Universiteit Leuven in Belgium using multipoint videoconferencing via ISDN lines at 384 kbit/s. The sessions, held in the evening, comprised oral presentations followed by interactive questions and answers, and concluded with a multi-site panel discussion. At all sites the session could be followed on two screens. The speaker/moderator or a questioner at a peripheral site, for example, was shown on the first screen and digital images were projected on the second screen. A multi-site voting system was provided. In weekly sessions between five rotating sites, a multipoint videoconference dealing with a different medical topic was presented and treated in a multidisciplinary way. During the three years of the project, 20 different peripheral sites were visited or revisited. On a five-point scale (with higher scores representing more positive evaluations), the average score for the quality of the image was 3.72 (SEM 0.01) and for sound 3.87 (SEM 0.01) ( n = 3743). The mean rating of the voting system was 3.76 (SEM 0.02) ( n = 3119). For sound, image quality and the voting system, respectively, 73%, 65% and 70% of all participants gave ratings of 'very good' or 'good'. The older participants gave slightly more positive ratings than the younger ones. Videoconferencing appears to be a suitable alternative to face-to-face seminars.
Telemedicine screening for diabetic retinopathy: staff and patient satisfaction
Authors: Rotvold Gunn-Hilde , Knarvik Undine , Johansen Monika Alise , Fossen Kristian
Published: April 2003

In a pilot project, telemedicine was used to conduct retinal examinations of diabetic patients in the Alta municipality of Norway. All health-care workers who were involved in the project were interviewed. The ophthalmologists found that the grading of the level of retinopathy was quicker with digital images than with slit-lamp examinations. Fifty patients with type II diabetes were invited to attend a telemedicine check-up and 42 did so. Patients were asked to complete a questionnaire after the telemedicine examination and we received 32 replies (a 76% response rate), of which 12 were from men and 20 from women. The patients expressed a high degree of satisfaction with the telemedicine examination. The results of the evaluation also clearly showed that trust between health personnel was of major importance in engendering positive attitudes. Confidence is the basis of good collaboration between the various professions in the health-care sector, between health-care levels and between patients and treatment providers - in terms not only of individuals' confidence but also of routines, procedures and the system as a whole.
Readiness for organizational change: A longitudinal study of workplace, psychological and behavioural correlates
Authors: Cunningham Charles E. , Woodward Christel A. , Shannon Harry S. , MacIntosh John , Lendrum Bonnie , Rosenbloom David , Brown Judy
Published: April 2003

To examine factors influencing readiness for healthcare organizational change, 654 randomly selected hospital staff completed questionnaires measuring the logistical and occupational risks of change, ability to cope with change and to solve jobrelated problems, social support, measures of Karasek's (1979) active vs. passive job construct (job demand× decision latitude) and readiness for organizational change. Workers in active jobs (Karasek, 1979) which afforded higher decision latitude and control over challenging tasks reported a higher readiness for organizational change scores. Workers with an active approach to job problem‐solving with higher job change self‐efficacy scores reported a higher readiness for change. In hierarchical regression analyses, active jobs, an active job problem‐solving style and job‐change self‐efficacy contributed independently to the prediction of readiness for organizational change. Time 1 readiness for organizational change scores and an active approach to job problem‐solving were the best predictors of participation in redesign activities during a year‐long re‐engineering programme.
The effect of empowerment on job knowledge: An empirical test involving operators of complex technology
Authors: Leach Desmond J. , Wall Toby D. , Jackson Paul R.
Published: April 2003

Two studies were conducted to investigate the predicted effect of empowerment on employees' job knowledge. Study 1 developed a measure of job knowledge, based on knowledge elicitation techniques, for use in work settings. Study 2 used that measure to examine change in employee knowledge following an empowerment initiative. Findings showed a substantial increase in job knowledge, particularly among less experienced employees. Improvements were also recorded for employee self‐confidence and strain, but not for motivation or job satisfaction. The wider theoretical and practical implications are discussed.
Trading on illusions: Unrealistic perceptions of control and trading performance
Authors: Fenton‐O'Creevy Mark , Nicholson Nigel , Soane Emma , Willman Paul
Published: April 2003

This paper examines the impact of illusory control beliefs on the performance of traders in financial instruments. The authors argue that the task and environment faced by traders are conducive to the development of illusions of control and that individual propensity to illusion of control will be (inversely) related to trader performance. Using an innovative computer task, designed to assess illusion of control in the field, data from 107 traders in four organizations showed individual differences in this bias to have a significant, inverse, association with performance, as measured by managers' ratings of trader performance and by total remuneration. The authors conclude that, at least in this context, illusion of control is maladaptive and that it is productive to take an individual difference approach to the study of such illusions. Implications for debates about the costs and benefits of positive illusions are discussed.
Effect of arsenite, maternal age, and embryonic sex on spina bifida, exencephaly, and resorption rates in the splotch mouse
Authors: Martin Lisa J. , Machado Antonio F. , Loza M. Angelica , Mao Gloria E. , Lee Grace S. , Hovland David N. , Cantor Rita M. , Collins Michael D.
Published: April 2003

BACKGROUND

This study examines interactions of a mutation inPax3, embryonic sex, advanced maternal age, and arsenite exposure in the splotch (Sp) mouse model, with the aim of describing gene‐environment interactions for neural tube defects and embryonic lethality.

METHODS

Splotch heterozygous C57BL/6J mice were crossed to produce offspring of three genotypes with a common maternal genotype that were exposed to either sodium arsenite on gestational day (GD) 8.0, or advanced maternal age (dams older than 12 months). Embryos were extracted on GD 12 and genotyped for bothPax3and sex.

RESULTS

Arsenite treatment was a significant contributor to both exencephaly and spina bifida. Advanced maternal age resulted in a high exencephaly rate inSp/Spfemale embryos (but not other genotypes) and a high overall resorption rate. Arsenite treatment and advanced maternal age resulted in elevated sex ratios (male:female) for heterozygous and wild‐type embryos. The sex ratio was highest for wild‐type embryos and was lowered as the number of mutantPax3alleles increased. The sex ratio was not significantly different from 1.0 for splotch homozygotes. Control litters had spina bifida rates that were 95% in homozygous, 6% in heterozygous, and 0% in wild‐type embryos.

CONCLUSIONS

If arsenite produces exencephaly by inactivating the Pax3 protein, then the fact that the exencephaly rate was increased inSp/Spembryos with no functional Pax3 indicates that arsenite may either induce this defect through additional pathways, or may alter the response via modifier genes. Genetic and environmental factors contributed to the determination of murine sex ratios, with female embryos being more susceptible to loss. Birth Defects Research (Part A) 67:231–239, 2003. © 2003 Wiley‐Liss, Inc.
Carbon monoxide‐induced axial skeletal dysmorphogenesis in the chick embryo
Authors: Alexander Peter G. , Tuan Rocky S.
Published: April 2003

BACKGROUND

Congenital axial skeletal defects affect two to three individuals per 1,000 live births. Without strong evidence for heritability, the cause is assumed to be multi‐factorial. Carbon monoxide (CO), an increasingly prevalent environmental toxicant, is a potential environmental component in the etiology of these defects. The chick embryo is a useful model for the characterization and assessment of the mechanism(s) of action of basic developmental mechanisms.

METHODS

We have determined a critical period and dose for CO teratogenicity and established a model of CO‐induced axial skeletal dysmorphogenesis in the chick embryo. The resulting phenotypes reveal a spectrum of axial skeletal defects ranging from minor defects of the vertebral canal and inter–vertebral discs, to thoraco–lumbar scoliosis, to a tailless phenotype reminiscent of caudal dysgenesis syndrome. These axial skeletal defects have been related to earlier developmental defects in somitogenesis, including errors in segmentation and epithelialization and the expression of the somitic epithelialization factor, Paraxis. We have examined patterns of cell death and apoptosis in CO exposed chick embryos to assess the target tissue(s) involved in the teratogenicity of CO.

RESULTS

With respect to the embryonic axis, the neural tube was found to be the most sensitive to CO‐induced apoptosis, followed by the somitic mesoderm and Hensen's node.

CONCLUSIONS

We hypothesize that the somitic defects and the resulting axial skeletal dysmorphogenesis are caused by disrupted neural tube or ectoderm functions related to somite formation and maintenance. We also hypothesize that CO‐induced dysmorphogenesis at this critical period of somitogenesis is caused by the overabundance of CO acting endogenously as a cellular signal, while coincidentally exerting its influence as a toxicant of oxygen delivery or utilization. Birth Defects Research (Part A) 67:219–230, 2003. Published 2003 Wiley‐Liss, Inc.
Neural and orofacial defects in Folbp1 knockout mice
Authors: Tang Louisa S. , Finnell Richard H.
Published: April 2003

BACKGROUND

Folic acid is essential for the development of the nervous system and other associated structures. Mice deficient in the folic acid‐binding protein one (Folbp1) gene display multiple developmental abnormalities, including neural and craniofacial defects. To better understand potential interactions between Folbp1 gene and selected genes involved in neural and craniofacial morphogenesis, we evaluated the expression patterns of a panel of crucial differentiation markers (Pax‐3, En‐2, Hox‐a1, Shh, Bmp‐4, Wnt‐1, and Pax‐1).

METHODS

Folbp1 mice were supplemented with low dosages of folinic acid to rescue nullizygotes from dying in utero before gestational day 10. The gene marker analyses were carried out by in situ hybridization.

RESULTS

In nullizygote embryos with open cranial neural tube defects, the downregulation of Pax‐3 and En‐2 in the impaired midbrain, along with an observed upregulation of the ventralizing marker Shh in the expanded floor plate, suggested an important regulatory interaction among these three genes. Moreover, the nullizygotes also exhibit craniofacial abnormalities, such as cleft lip and palate. Pax‐3 signals in the impaired medial nasal primordia were significantly increased, whereas Pax‐1 showed no expression in the undeveloped lateral nasal processes. Although Shh was downregulated, Bmp‐4 was strongly expressed in the medial and lateral nasal processes, highlighting the antagonistic activities of these molecules.

CONCLUSIONS

Impairment of Folbp1 gene function adversely impacts the expression of several critical signaling molecules. Mis‐expression of these molecules, perhaps mediated by Shh, may potentially contribute to the observed failure of neural tube closure and the development of craniofacial defects in the mutant mice. Birth Defects Research (Part A) 67:209–218, 2003. © 2003 Wiley‐Liss, Inc.
Time‐varying intercepts and equilibrium analysis: an extension of the dynamic almost ideal demand model
Authors: Deschamps Philippe J.
Published: April 2003

Demographic effects and user costs in demand systems have usually been modelled explicitly. A more robust approach is a state space formulation of the demand system, where time‐varying intercepts account for the effects of unobservable variables. The author embeds such a system in a vector autoregressive distributed lag model, with a Bayesian hierarchical prior. The model is estimated by a Markov chain Monte Carlo method on samples involving quarterly US and UK data. In the US case, the results are compared with a previously published cointegration analysis of the same data. Copyright © 2002 John Wiley & Sons, Ltd.
Retesting Fair's (1978) model on infidelity
Authors: Wells Curt
Published: April 2003

Modern econometrics stresses the diagnostic testing of estimated models as an important part of the model‐building process. In a survey article published in this journal (Pagan and Vella 1989), methods for testing the validity of the assumptions underlying the censored regression of the Tobit model were presented. This paper questions the numerical results presented there. Indeed, my results concerning the tests when applied to Fair's well‐known model for infidelity (1978) are the opposite of those presented in this journal. Copyright © 2003 John Wiley & Sons, Ltd.
Employee “spy” software: Should you use it?
Authors: Barlow Judith , Bean LuAnn , Hott David D.
Published: April 2003

Cyber loafing costs companies billions of dollars each year. But should you use the latest employee
“spy” software to monitor your firm's computer users? The authors review a popular new
surveillance tool, and discuss both its benefits and possible risks. © 2003 Wiley Periodicals,
Inc.
It's the law: Protecting audit suspects' rights
Authors: Sinason David , Pacini Carl , Hillison William
Published: April 2003

Investigations into employee embezzlement, theft, and money laundering have taken on a new wrinkle: many now
fall under the requirements of the Fair Credit Reporting Act. How does this affect audits and
investigations? © 2003 Wiley Periodicals, Inc.
How are U.S. and international audit rules changing?
Authors: Tatum Kay W. , Munter Paul
Published: April 2003

Major efforts are underway to improve the quality of external audits—both in the United States and
abroad. And big changes are in the wind. © 2003 Wiley Periodicals, Inc.
Mitochondria‐mediated caspase‐independent apoptosis induced by cadmium in normal human lung cells
Authors: Shih Chwen‐Ming , Wu Jui‐Sheng , Ko Wun‐Chang , Wang Leng‐Fang , Wei Yau‐Huei , Liang Hsiao‐Fang , Chen Yen‐Chou , Chen Chien‐Tsu
Published: April 2003

Cadmium, a well‐known environmental hazard, has caused serious health problems in humans and animals. Accumulating evidence suggests the cadmium toxicity is mediated by oxidative stress‐induced cell death. However, the molecular signaling underlying cadmium‐induced apoptosis remains unclear. In this study, we demonstrate here that cadmium induced mixed types of cell death including primary apoptosis (early apoptosis), secondary necrosis (late apoptosis), and necrosis in normal human lung cells, MRC‐5, as revealed by chromatin condensation, phosphatidylserine (PS) externalization, and hypodiploid DNA content. The total apoptotic cells reached a plateau of around 40.0% after 24 h exposure of 100 μM cadmium. Pretreatment with Z‐Val–Ala–Asp–fluoromethylketone (Z‐VAD–fmk), a broad spectrum of caspase inhibitor, could not rescue apoptotic cells from cadmium toxicity. Coincidently, we failed to detect the activation of pro‐caspase‐3 and cleavage of PARP by immunoblot, which implies the apoptogenic activity of cadmium in MRC‐5 cells is caspase‐independent. JC‐1 staining also indicated that mitochondrial depolarization is a prelude to cadmium‐induced apoptosis, which was accompanied by a translocation of caspase‐independent pro‐apoptotic factor apoptosis‐inducing factor (AIF) into the nucleus as revealed by the immunofluorescence assay. In summary, this study demonstrated for the first time that cadmium induced a caspase‐independent apoptotic pathway through mitochondria‐mediated AIF translocation into the nucleus. J. Cell. Biochem. 89: 335–347, 2003. © 2003 Wiley‐Liss, Inc.
Leptin induces increased α2(I) collagen gene expression in cultured rat hepatic stellate cells
Authors: Saxena Neeraj K. , Saliba George , Floyd Jeffrey J. , Anania Frank A.
Published: April 2003

Leptin is a 16‐kDa hormone with an array of biologic actions. We, and others, have demonstrated that leptin is critical to the development of liver fibrogenesis both in vitro and in the lean littermates of ob/ob mice exposed to carbon tetrachloride (CCl4). Controversy exists as to whether leptin can act as a direct cytokine in the development of increased collagen expression, and whether ob/ob mice are resistant to potential injury from CCl4. Here, we provide evidence that strongly suggests that leptin acts to increase nascent production of mRNA for the α2(I) collagen gene based upon ribonuclease protection analysis (RPA). Actinomycin D, but not cyclohexamide, or the pan‐neutralizing antibody to transforming growth factor beta one (TGFβ1), significantly diminished the effect of leptin on total α2(I) collagen mRNA levels. Further evidence that leptin acts directly on HSCs to alter gene expression in liver wounding is demonstrated by enhanced binding of phosphorylated signal transduction and activator of transcription factor 3 (pStat3) to a cis‐inducible element (SIE) oligonucleotide by electrophoretic mobility shift assay (EMSA). This consensus sequence is responsible for production of a critical collagen transcription factor, AP‐1. Finally, we have demonstrated from the ob/ob mouse model that these animals are at least as sensitive to CCl4 as their respective lean animals as assessed by serum alanine aminotransferase (ALT) measurements. Taken together, the current data provide a continued framework that leptin is a profibrogenic cytokine and plays a key role in liver fibrosis. J. Cell. Biochem. 89: 311–320, 2003. © 2003 Wiley‐Liss, Inc.
ERK, JNK, and p38 MAP kinases differentially regulate proliferation and migration of phenotypically distinct smooth muscle cell subtypes
Authors: Kavurma Mary M. , Khachigian Levon M.
Published: April 2003

Proliferation and migration of vascular smooth muscle cells (SMCs) are important processes involved in the pathogenesis of vascular disorders such as atherosclerosis and post‐angioplasty restenosis. Here we demonstrate that proliferation and migration of specific SMC subtypes is mitogen‐activated protein (MAP) kinase‐dependent. WKY12‐22 SMCs derived from the aortae of 12 day‐old pup rats proliferate and migrate faster than WKY3M‐22 SMCs derived from the aortae of adult rats. WKY12‐22 and WKY3M‐22 cells equally expressed the active forms of phospho (Thr183/Tyr185)‐c‐Jun N‐terminal kinase (JNK) and phospho (Tyr182)‐p38, whereas the activity of extracellular signal‐regulated kinase (ERK) was greater in WKY12‐22 cells compared with WKY3M‐22 cells. Proliferation of both SMC subtypes was attenuated by PD98059, SP600125 and SB202190, inhibitors of ERK, JNK, and p38, respectively. However, inhibition of PD98059 had a more profound effect on WKY12‐22 SMCs. Furthermore, migration of WKY12‐22 and WKY3M‐22 cells was inhibited by SP600125 and SB202190, however, PD98059 failed to influence migration of either SMC subtype. Hence, migration of both SMC subtypes is JNK‐ and p38‐dependent, but not ERK‐dependent. These findings demonstrate that SMC heterogeneity is mediated, at least in part, by the activity of specific MAP kinase subtypes. J. Cell. Biochem. 89: 289–300, 2003. © 2003 Wiley‐Liss, Inc.
Identification of calreticulin as a nuclear matrix protein associated with human colon cancer
Authors: Brünagel Gisela , Shah Uzma , Schoen Robert E. , Getzenberg Robert H.
Published: April 2003

Colon cancer is one of the most common malignancies among populations in the United States and Western Europe, and one of the leading causes of worldwide morbidity and mortality due to cancer. The early detection of colon cancer is central to the effective treatment of this disease and early detection markers are needed. We have demonstrated that high‐resolution two‐dimensional gel analysis of nuclear matrix proteins (NMPs) demonstrated a specific oncological fingerprint of colon cancer. Utilizing this approach, four proteins specific for colon cancer was identified. Additionally, one protein was expressed much more strongly in colon cancer compared to adjacent and normal donor tissue. The amino acid composition of this protein revealed sequence similarity with calreticulin. The multi‐functional protein, calreticulin, is normally found in the lumen of the endoplasmic reticulum although some reports have described a nuclear localization of the protein. The aim of this study was to confirm the identity of the protein as calreticulin as well as to evaluate the localization of calreticulin in the nuclear matrix of colon cancer tissue. J. Cell. Biochem. 89: 238–243, 2003. © 2003 Wiley‐Liss, Inc.
Primary cilium—is it an osteocyte's strain‐sensing flowmeter?
Authors: Whitfield James F.
Published: April 2003

With few exceptions, the non‐cycling cells in a vast range of animals including humans have a non‐motile primary cilium that extends from the mother centriole of the pair of centrioles in their centrosomes located between their Golgi apparatuses and nuclei. It has very recently been shown that the primary cilium of a dog or a mouse embryonic kidney cell is a fluid flowmeter studded with heterodimeric complexes of mechanoreceptors linked to Ca2+‐permeable cation channels that when the cilium is bent can send Ca2+ signals into the cell and beyond to neighboring cells through gap junctions. More than 30 years ago, osteocytes were reported also to have primary cilia, but this was promptly ignored or forgotten. Osteocytes are the bones' strain sensors, which measure skeletal activity from the effects of currents of extracellular fluid caused by their bones being bent and squeezed during various activities such as walking and running. Since bending a kidney cell's primary cilium can send a Ca2+ wave surging through itself and its neighbors, the bending of an osteocyte's primary cilium by sloshing extracellular fluid is likely to do the same thing and thus be involved in measuring and responding to bone strain. J. Cell. Biochem. 89: 233–237, 2003. © 2003 Wiley‐Liss, Inc.
Enhancement of albumin expression in bone tissues with healing rat fractures
Authors: Yamaguchi Masayoshi , Igarashi Aki , Misawa Hiroyuki , Tsurusaki Yoshinori
Published: April 2003

The characterization of 66 kDa protein molecule, a major protein component which is produced from femoral‐diaphyseal tissues with fracture healing (Igarashi and Yamaguchi [2002] Int. J. Mol. Med. 9:503–508), was investigated. Weaning rats were killed at 7 and 14 days after femoral fracture. When the femoral‐diaphyseal tissues with fracture healing were cultured for 48 h in a serum‐free medium, many proteins in the bone tissues were released into the medium. Analysis with sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS–PAGE) showed that a protein molecule of approximately 66 kDa was markedly increased in culture medium from bone tissues with fracture healing. N‐terminal sequencing of 66 kDa protein indicated that its N‐terminus was identical to that of rat albumin. Western blot analysis of medium 66 kDa protein showed expression of albumin. This expression was significantly enhanced by fracture healing. The expression of albumin was seen in the diaphyseal (cortical bone) and metaphyseal (trabecular bone) tissues of rat femur. When the femoral‐diaphyseal tissues obtained at 7 days after femoral fracture were cultured in a serum‐free medium containing either vehicle, parathyroid hormone (1–34) (10−7 M), insulin‐like growth factor‐I (10−8 M) or zinc acexamate (10−4 M), medium albumin was significantly increased in the presence of those bone‐stimulating factors. The addition of albumin (0.5 or 1.0 mg/ml of medium) caused a significant increase in calcium and deoxyribonucleic acid contents in the femoral‐diaphyseal and ‐metaphyseal tissues obtained from normal rats in vitro. The present study demonstrates that fracture healing induces a remarkable production of albumin which is a major protein component produced from femoral‐diaphyseal tissues of rats, and that albumin has an anabolic effect on bone components. J. Cell. Biochem. 89: 356–363, 2003. © 2003 Wiley‐Liss, Inc.
Transcriptional profiling of human osteoblast differentiation
Authors: Billiard J. , Moran R.A. , Whitley M.Z. , Chatterjee‐Kishore M. , Gillis K. , Brown E.L. , Komm B.S. , Bodine P.V.N.
Published: April 2003

Osteoblast differentiation is a key aspect of bone formation and remodeling. To further our understanding of the differentiation process, we have developed a collection of conditionally immortalized adult human osteoblast cell lines representing discrete stages of differentiation. To evaluate changes in gene expression associated with differentiation, polyA(+) RNA from pre‐osteoblasts, early and late osteoblasts, and pre‐osteocytes was subjected to gene chip analysis using the Affymetrix Hu6800 chip in conjunction with an Affymetrix custom chip enriched in bone and cartilage cDNAs. Overall, the expression of 47 genes was found to change threefold or more on both chips between the pre‐osteoblastic and pre‐osteocytic stages of differentiation. Many of the observed differences, including down‐regulation of collagen type I and collagen‐processing enzymes, reflect expected patterns and support the relevance of our results. Other changes have not been reported and offer new insight into the osteoblast differentiation process. Thus, we observed regulation of factors controlling cell cycle and proliferation, reflecting decreased proliferation, and increased apoptosis in pre‐osteocytic cells. Elements maintaining the cytoskeleton, extracellular matrix, and cell–cell adhesion also changed with differentiation reflecting profound alterations in cell architecture associated with the differentiation process. We also saw dramatic down‐regulation of several components of complement and other immune response factors that may be involved in recruitment and differentiation of osteoclasts. The decrease in this group of genes may provide a mechanism for controlling bone remodeling of newly formed bone. Our screen also identified several signaling proteins that may control osteoblast differentiation. These include an orphan nuclear receptor DAX1 and a small ras‐related GTPase associated with diabetes, both of which increased with increasing differentiation, as well as a high mobility group‐box transcription factor, SOX4, that was down‐regulated during differentiation. In summary, our study provides a comprehensive transcriptional profile of human osteoblast differentiation and identifies several genes of potential importance in controlling differentiation of osteoblasts. J. Cell. Biochem. 89: 389–400, 2003. © 2003 Wiley‐Liss, Inc.