bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantitative growth hormone secretion and final adult height
Authors: Trainer P. J. , Palermo M. , Kirk J. M. W. , Fanciulli G. , Perry L. H. , Delitala G. , Besser G. M.
Published: May 2003

OBJECTIVE

The relationship of quantitative GH secretion to height, growth velocity and puberty is complex and has been the subject of extensive study in children. This study was designed to relate quantitative GH secretion to final height.

SUBJECTS

Twenty tall (> 183 cm, 90th centile for adult height) and 20 short (< 166 cm, 10th centile) postpubertal men who had recently completed linear growth (age range 18–27 years).

MEASUREMENTS

GH dynamics were studied on four occasions; insulin (0.15 units/kg, iv)‐induced hypoglycaemia and GHRH (100 mg, iv) with and without the anticholinesterase, pyridostigmine (120 mg orally). Spontaneous nocturnal GH secretion was assessed by 20 minute sampling from 2100 h until 0600 h. GH was measured by IRMA. Analysis was by comparison of peak GH response and area under the curve (AUC). GH profiles were further analysed using the ‘pulsar’ programme.

RESULTS

The mean height in the tall group was 187.7 cm (range 183–197) compared to 163.5 cm (range 160–166) for the short group. No difference existed between groups in the GH response to hypoglycaemia or GHRH with and without pyridostigmine. Area under the curve, pulse number, length and amplitude for spontaneous nocturnal GH secretion showed no significant difference between the tall and short subjects. Serum IGF‐I (mean 230.5 ± 15.4 vs. 230.6 ± 18.9 μg/l) did not differ between the groups.

CONCLUSIONS

Quantitative GH secretion does not appear to be an important determinant of final height in healthy individuals.
Acute pancreatitis and parotitis induced by methimazole in a patient with Graves' disease
Authors: Taguchi Manabu , Yokota Masafumi , Koyano Hajime , Endo Yuzo , Ozawa Yasunori
Published: May 2003

A wide variety of adverse effects of methimazole (MMI) have been reported. Here we report a new MMI‐induced disorder, acute pancreatitis and parotitis. Three weeks after a woman started MMI treatment for Graves' disease, she developed a high fever, painful parotid swelling and dull pain in the upper abdomen with elevation of the serum levels of salivary and pancreatic enzymes. These abnormalities disappeared soon after the withdrawal of MMI. However, the same abnormalities were rapidly provoked when MMI was reintroduced. Marked increases in the leucocyte count and CRP were also observed during these episodes. The possible mechanisms of MMI‐induced pancreatitis/parotitis are discussed.
Communicating and judging the quality of qualitative research: the need for a new language
Authors: Fade S. A.
Published: May 2003

Background Traditionally UK dietitians have tended to take a more quantitative approach to research. Qualitative research which gives an in‐depth view of people's experiences and beliefs is also now being used to help answer some important dietetic research questions.

Review A review of the limited number of qualitative research papers in the Journal of Human Nutrition and Dietetics 1990–2002 (nine papers in all), revealed a lack of specific discussion of the quality strategies commonly used in qualitative research. This could indicate a less than robust approach, but might also reflect a different perspective on quality, or simply the difficulties associated with disseminating qualitative research to a profession whose members lack familiarity with the language. The fact that qualitative research seems to be used rarely may also indicate a poor understanding of its role.

Purpose of this paper This paper seeks to clarify the potential role of qualitative research and draws on previously published guidelines for demonstrating quality. It is hoped that this will offer dietitians a framework for carrying out qualitative research and a language for reporting it, as well acting as a stimulus for discussion.
The estimation of food portion sizes: a comparison between using descriptions of portion sizes and a photographic food atlas by children and adults
Authors: Frobisher C. , Maxwell S. M.
Published: May 2003

Background Food Photographs and standard portion sizes have been used with adults to assess portion size when recording dietary intake. The effectiveness of these methods may be reduced when memory/recall is required and children may have problems using these techniques.

Methods Adults (47) and children (37) were recruited from amongst university personnel, their children and children's friends to assess portion sizes of nine self‐served amounts of selected food items using food photographs and standard descriptions of portion sizes. Portion sizes were estimated directly after self‐serving and three – 4 days later.

Results Substantial differences in the estimate of portion sizes were observed for most foods regardless of the method used or the age of the subjects, median difference range: −52–100%. For children there were greater errors using both methods than for adults. Significant differences were found between the two methods of estimating weight. The food atlas provided higher median estimated weights for the majority of the food items. There were very few differences in the estimation of portion sizes between the two testing periods.

Conclusion The findings would suggest that either an alternative method or a modification of the methods used here for estimating portion sizes in young subjects, for example standard food portion sizes for children of different ages such as those that are being developed by the Food Standards Agency, would be more appropriate.
Why do diabetic patients not attend appointments with their dietitian?
Authors: Spikmans F. J. M. , Brug J. , Doven M. M. B. , Kruizenga H. M. , Hofsteenge G. H. , Van Bokhorst‐van der Schueren M. A. E.
Published: May 2003

Purpose Determining the prevalence of and possible reasons for nonattendance of diabetic nutritional care clinics.

Methods Data were collected by means of a telephone survey and a review of patient records among 293 (166 attendees and 127 nonattendees) patients undergoing outpatient treatment at a university hospital. The t‐tests, chi‐square tests and logistic regression analysis were used to identify potential determinants of nonattendance. The theoretical framework was primarily based on the Health Belief Model.

Results In univariate analysis, nonattendance at the clinic was associated with a number of factors such as not visiting other care givers, risk perceptions, body‐mass index, self‐rated health, health locus of control, satisfaction with the dietitian, feelings of obligation to attend, and beliefs about the effectiveness of the treatment. In multivariate analysis only health locus of control and obligation to attend the visit were significant predictors of attendance. A significant number of respondents further reported that they perceived their visits to the dietitian to be of little use.

Conclusion One in three diabetic patients undergoing outpatient treatment skipped one or more visits to their dietitian. Patient education to improve attendance should focus primarily on convincing patients that they can contribute to their own health, and may stress the obligation the patients have when making an appointment with the dietitian.
A comparative study of the quantitative accuracy of three‐dimensional reconstructions of spinal cord from serial histological sections
Authors: Duerstock B. S. , Bajaj C. L. , Borgens R. B.
Published: May 2003

We evaluated the accuracy of estimating the volume of biological soft tissues from their three‐dimensional (3D) computer wireframe models, reconstructed from histological data sets obtained from guinea‐pig spinal cords. We compared quantification from two methods of three‐dimensional surface reconstruction to standard quantitative techniques, Cavalieri method employing planimetry and point counting and Geometric Best‐Fitting. This involved measuring a group of spinal cord segments and test objects to evaluate the accuracy of our novel quantification approaches. Once a quantitative methodology was standardized there was no statistical difference in volume measurement of spinal segments between quantification methods. We found that our 3D surface reconstructions’ ability to model precisely actual soft tissues provided an accurate volume quantification of complex anatomical structures as standard approaches of Cavalieri estimation and Geometric Best‐Fitting. Additionally, 3D reconstruction quantitatively interrogates and three‐dimensionally images spinal cord segments and obscured internal pathological features with approximately the same effort required for standard quantification alone.
Measurement of the laser pulse width on the microscope objective plane by modulated autocorrelation method
Authors: Cannone F. , Chirico G. , Baldini G. , Diaspro A.
Published: May 2003

We report on the construction details of a compact autocorrelator set‐up for the measurement of the width of infrared laser pulses at the focal plane of a microscope for two‐photon excitation fluorescence imaging. One of the novelties of the set‐up, which leads to an improved measurement accuracy, is the use of a modulation technique that is achieved by mounting one of the interferometer mirrors on a loudspeaker driven by a sinusoidal bias at low frequency. A non‐linear least‐square routine selects only that part of the fluorescence signal that is modulated at the same frequency as the loudspeaker bias. To further increase the accuracy, the laser pulse width is obtained from a series of measurements at different values of the modulation bias. The autocorrelator is a compact single bread‐board (10 × 20 cm); it is PC‐controlled both for the acquisition and the analysis of the data and can be coupled to different ports of the microscope. The increase in the pulse width measured for three different ports of the microscope is well accounted for by the group velocity dispersion and the glass thickness of the optics found along these paths.
Atomic vacancy‐induced friction on the graphite surface: observation by lateral force microscopy
Authors: Paredes J. I. , Martínez‐Alonso A. , Tascón J. M. D.
Published: May 2003

Lateral force microscopy has been employed to investigate the frictional behaviour of atomic vacancies on the graphite surface. Such a study was only made possible by the controlled expansion of originally single‐atom vacancies into multiatom vacancies, employing oxygen plasma etching for this purpose. Enhanced friction was observed on the vacancy regions compared with pristine areas of graphite, the origin of which is examined and discussed.
Association of right ventricular dysfunction and Cheyne–Stokes respiration in patients with chronic heart failure
Authors: Christ Michael , Grimm Wolfram , Rostig Sven , Klima Theresia , Fenske Hendrik , Becker Heinrich F. , Vogelmeier Claus , Maisch Bernhard
Published: May 2003

Cheyne–Stokes respiration (CSR) is present in up to 40% of patients with congestive heart failure (CHF) and is an independent risk factor for increased overall mortality. We examined whether CSR is associated with right ventricular (RV) dysfunction in CHF patients. Parameters of RV function were assessed by two‐dimensional echocardiography and tissue velocity imaging in 42 patients (aged 23–75 years) with a left ventricular (LV) ejection fraction below 40%. Respiratory polygraphy revealed CSR with an central apnea–hypopnea index (CAHI) >10 h−1 in 13 of the 42 patients (31%). Demographic characteristics did not differ among the patient groups. The velocity of the tricuspid annular systolic motion (TASM), a parameter reflecting systolic RV function, was significantly reduced in CHF patients with CSR (10.5 ± 2.3 cm s−1) compared with those without CSR (15.0 ± 5.1 cm s−1, P = 0.004), and was inversely associated with the CAHI (y = 15.2–0.2x; r = 0.46, P = 0.003). The RV dimensions were significantly increased and the fractional RV area changes significantly reduced in CHF patients with CSR (33 ± 17 versus 48 ± 20%; P = 0.04). Doppler parameters of pulmonary artery flow indicate higher pulmonary artery pressures in CSR patients compared with patients without CSR, which is also reflected by an increased RV free‐wall thickness in CSR patients (6.5 ± 1.1 vs. 5.3 ± 1.3 mm; P = 0.05). Parameters of systolic LV function, forced expiratory volume in 1 s (FEV1), and PaO2 and PaCO2 were not different among patients with or without CSR. In conclusion, CSR is associated with depressed systolic RV function and increased RV dimensions in CHF patients. Future studies will show whether optimized treatment of CSR will improve RV function.
Actigraphy suggests age‐related differences in napping and nocturnal sleep
Authors: Yoon In‐Young , Kripke Daniel F. , Youngstedt Shawn D. , Elliott Jeffrey A.
Published: May 2003

The aim of this study was to contrast the time distribution of out‐of‐bed napping in young and older adults through recordings of wrist activity, and to evaluate the correlates of napping with nocturnal sleep. Seventy‐three young adults between 18 and 32 years and 60 older adults between 60 and 75 years of age participated in the study. Subjects were selected for good general health and had few sleep complaints. They wore wrist‐activity monitors and kept daily sleep logs for 1 week. Automatic sleep scoring was edited by the authors, supplemented by sleep logs and illumination data as well as activity data. Napping episodes were modestly increased in older adults, but there was no difference in the daily duration of napping. Older adults napped more in the evening (especially within 2 h before bedtime), whereas young adults napped more in the afternoon. The older adults with evening naps (n = 31) showed earlier nocturnal wake‐up times and decreased nocturnal sleep duration compared with the older adults without evening naps (n = 29). There was no difference in nocturnal sleep between young adults with afternoon naps (n = 32) and without afternoon naps (n = 41). In determining the effects of napping on nocturnal sleep, timing of napping and age are important. Maintaining alertness during the evening (e.g. by bright light exposure or moderate exercise) would be a possible approach to delay wake‐up times in older adults.
Ocular and visual defects amongst people with intellectual disabilities participating in Special Olympics
Authors: Margaret Woodhouse J. , Adler Paul M. , Duignan Ann
Published: May 2003

Purpose: To analyse data from vision screening of people with intellectual disabilities from the UK participating in Special Olympics during the National Summer Games in Cardiff 2001, in order to determine visual status and access to eye care.

Methods: Athletes were invited to take part in vision screening, according to Special Olympics protocols.

Results: Testability rates were high. Findings confirmed the high prevalence of eye and vision defects reported in other studies of people with intellectual disabilities. In particular, visual acuity was below normal for most athletes. Significant improvement to acuity could be achieved with spectacles although correction after full refraction did not always provide normal vision. Over 40% of athletes undergoing full refraction had below normal corrected acuity.

Conclusions: Athletes with intellectual disabilities were no more likely to access eye care and have adequate spectacle correction than other people with intellectual disabilities. Optometrists and carers need to be aware of the high prevalence of defects and the importance of regular eye examinations in people with intellectual disabilities.
The repeatability and validity of dynamic retinoscopy in assessing the accommodative response
Authors: McClelland J. F. , Saunders K. J.
Published: May 2003

Dynamic retinoscopy (DR) is an objective technique that has been used successfully to examine accommodative function of non‐communicative patients. However, there are few studies examining its repeatability and validity. This paper addresses the repeatability and validity of a form of DR (a modified Nott technique), by comparing results to the Shin‐Nippon SRW‐5000 Autorefractor whose validity and repeatability have previously been demonstrated. Accommodative responses of 41 subjects (aged 6–43 years) were assessed using DR and the Shin‐Nippon SRW‐5000 Autorefractor. Three different target demands were used (10, 6 and 4 D). DR was shown to be repeatable for all target demands (paired t‐test, p > 0.05). The results demonstrated good agreement between the autorefractor and DR. The results of the present study suggest that DR is a repeatable and valid objective technique for assessing accommodative function.
Acute Management of Seizures in the Syndromes of Idiopathic Generalized Epilepsies
Authors: Wheless James W.
Published: May 2003

Summary: Three of the seizure types (myoclonic, absence, and generalized tonic‐clonic) and syndromes associated with idiopathic generalized or genetic epilepsies can present an acute status epilepticus picture that requires acute therapy. These are not the usual seizures observed in status epilepticus because most of these patients have secondary generalized or symptomatic generalized convulsive seizures. In this review, I discuss the unique presentation and treatment options for the acute management of seizures in the syndromes of idiopathic generalized epilepsy (IGE), with special emphasis on the seizures of status epilepticus, which persist over time or occur in a series without recovery of consciousness.
Clinical and Electrophysiologic Predictors of Ventricular Tachyarrhythmia Recurrence in Patients with Implantable Cardioverter Defibrillators
Authors: Gillis Anne M. , Sheldon Robert S. , Wyse D. George , Duff Henry J. , Cassidy Margaret R. , Mitchell L. Brent
Published: May 2003

Introduction: Not all patients experience recurrent sustained ventricular tachyarrhythmias after placement of an implantable cardioverter defibrillator (ICD). We evaluated the clinical and electrophysiologic predictors of ventricular tachycardia (VT) and ventricular fibrillation (VF) recurrence following ICD implantation.

Methods and Results: Consecutive patients

(n = 133)

underwent

4 ± 3

serial electrophysiologic studies (EPS) over

50 ± 26 months

following ICD implantation. Sustained VT/VF could always be induced during follow‐up EPS in 49 patients; sustained VT/VF was sometimes induced during follow‐up EPS in 47 patients; and sustained VT/VF could never be induced during follow‐up EPS in 37 patients. Spontaneous VT/VF requiring ICD therapy occurred in 107 patients during follow‐up. Patients with sustained VT/VF that was always inducible or sometimes inducible during follow‐up experienced more frequent episodes of VT/VF following ICD implant (20.5, 95% CI 12.7–33.0; and 17.8, 95% CI 11.3–28.1 episodes/patient respectively; vs 3.0, 95% CI 2.0–4.6 episodes/patient for patients with VT/VF never induced,

P < 0.001

). Inducibility of sustained VT/VF post‐ICD implant

(P < 0.001)

and sustained VT as the presenting arrhythmia

(P = 0.02)

were independent predictors of spontaneous VT/VF recurrence.

Conclusion: Reproducibly inducible VT/VF following ICD implantation predicts a high probability of VT/VF recurrence and identifies a cohort of patients who experience frequent episodes of VT/VF over time. Persistent noninducibility of sustained VT/VF identifies a group of patients who experience no or very few episodes of VT/VF recurrence.
(J Cardiovasc Electrophysiol, Vol. 14, pp. 492‐498, May 2003)
Magnetic Resonance Imaging Findings in Patients Meeting Task Force Criteria for Arrhythmogenic Right Ventricular Dysplasia
Authors: Tandri Harikrishna , Calkins Hugh , Nasir Khurram , Bomma Chandra , Castillo Ernesto , Rutberg Julie , Tichnell Crystal , Lima João A.C. , Bluemke David A.
Published: May 2003

Introduction: Magnet resonance imaging (MRI) findings in patients meeting Task Force criteria for the diagnosis of arrhythmogenic right ventricular dysplasia (ARVD) have not been systematically described. We report qualitative and quantitative MRI findings in ARVD using state‐of‐the‐art MRI.

Methods and Results: MRI was performed on 12 patients with ARVD who were prospectively diagnosed using the Task Force criteria. The imaging protocol included breath‐hold double inversion recovery spin‐echo and gradient‐echo images. Ventricular volumes and dimensions were compared to 10 age‐ and sex‐matched normal volunteers. High intramyocardial T1 signal similar to fat signal was observed in 9 (75%) of the 12 patients and in none of the controls. Right ventricular (RV) hypertrophy was seen in 5 (42%) patients, trabecular disarray in 7 (59%), and wall thinning in 3 (25%). Both the RV end‐diastolic diameter and the outflow tract area were significantly higher in ARVD patients compared to controls (51.2 vs 43.2 mm,

P < 0.01

; and 14.5 vs

9.3 cm2, P < 0.01

, respectively). ARVD patients had a higher RV end‐diastolic volume index and lower RV ejection fraction compared with controls (127.4 vs

87.5, P < 0.01

; and 41.6% vs 57%,

P < 0.01

, respectively).

Conclusion: High intramyocardial T1 signal indicative of fat is seen in a high percentage (75%) of patients who meet the Task Force criteria for ARVD. Trabecular disarray is seen more frequently than wall thinning and aneurysms. RV dimensions and volumes differ significantly in ARVD compared to controls, indicating a role for quantitative evaluation in the diagnosis of ARVD.
(J Cardiovasc Electrophysiol, Vol. 14, pp. 476‐482, May 2003)
deep-orange and carnation define distinct stages in late endosomal biogenesis in Drosophila melanogaster
Authors: Sriram V. , Krishnan K.S. , Mayor Satyajit
Published: May 2003

Endosomal degradation is severely impaired in primary hemocytes from larvae of eye color mutants of Drosophila. Using high resolution imaging and immunofluorescence microscopy in these cells, products of eye color genes, deep-orange (dor) and carnation (car), are localized to large multivesicular Rab7-positive late endosomes containing Golgi-derived enzymes. These structures mature into small sized Dor-negative, Car-positive structures, which subsequently fuse to form tubular lysosomes. Defective endosomal degradation in mutant alleles of dor results from a failure of Golgi-derived vesicles to fuse with morphologically arrested Rab7-positive large sized endosomes, which are, however, normally acidified and mature with wild-type kinetics. This locates the site of Dor function to fusion of Golgi-derived vesicles with the large Rab7-positive endocytic compartments. In contrast, endosomal degradation is not considerably affected in car1 mutant; fusion of Golgi-derived vesicles and maturation of large sized endosomes is normal. However, removal of Dor from small sized Car-positive endosomes is slowed, and subsequent fusion with tubular lysosomes is abolished. Overexpression of Dor in car1 mutant aggravates this defect, implicating Car in the removal of Dor from endosomes. This suggests that, in addition to an independent role in fusion with tubular lysosomes, the Sec1p homologue, Car, regulates Dor function.
Role of Drosophila Rab5 during endosomal trafficking at the synapse and evoked neurotransmitter release
Authors: Wucherpfennig Tanja , Wilsch-Bräuninger Michaela , González-Gaitán Marcos
Published: May 2003

During constitutive endocytosis, internalized membrane traffics through endosomal compartments. At synapses, endocytosis of vesicular membrane is temporally coupled to action potential–induced exocytosis of synaptic vesicles. Endocytosed membrane may immediately be reused for a new round of neurotransmitter release without trafficking through an endosomal compartment. Using GFP-tagged endosomal markers, we monitored an endosomal compartment in Drosophila neuromuscular synapses. We showed that in conditions in which the synaptic vesicles pool is depleted, the endosome is also drastically reduced and only recovers from membrane derived by dynamin-mediated endocytosis. This suggests that membrane exchange takes place between the vesicle pool and the synaptic endosome. We demonstrate that the small GTPase Rab5 is required for endosome integrity in the presynaptic terminal. Impaired Rab5 function affects endo- and exocytosis rates and decreases the evoked neurotransmitter release probability. Conversely, Rab5 overexpression increases the release efficacy. Therefore, the Rab5-dependent trafficking pathway plays an important role for synaptic performance.
α-Adducin dissociates from F-actin and spectrin during platelet activation
Authors: Barkalow Kurt L. , Italiano Joseph E. , Chou Denise E. , Matsuoka Yoichiro , Bennett Vann , Hartwig John H.
Published: May 2003

Aspectrin-based skeleton uniformly underlies and supports the plasma membrane of the resting platelet, but remodels and centralizes in the activated platelet. α-Adducin, a phosphoprotein that forms a ternary complex with F-actin and spectrin, is dephosphorylated and mostly bound to spectrin in the membrane skeleton of the resting platelet at sites where actin filaments attach to the ends of spectrin molecules. Platelets activated through protease-activated receptor 1, FcγRIIA, or by treatment with PMA phosphorylate adducin at Ser726. Phosphoadducin releases from the membrane skeleton concomitant with its dissociation from spectrin and actin. Inhibition of PKC blunts adducin phosphorylation and release from spectrin and actin, preventing the centralization of spectrin that normally follows cell activation. We conclude that adducin targets actin filament ends to spectrin to complete the assembly of the resting membrane skeleton. Dissociation of phosphoadducin releases spectrin from actin, facilitating centralization of spectrin, and leads to the exposure of barbed actin filament ends that may then participate in converting the resting platelet's disc shape into its active form.
PMN transendothelial migration decreases nuclear NFκB in IL-1β–activated endothelial cells
Authors: Cepinskas Gediminas , Savickiene Jurate , Ionescu Carmen V. , Kvietys Peter R.
Published: May 2003

During the systemic inflammatory response, circulating cytokines interact with the vascular endothelium, resulting in activation and nuclear accumulation of the nuclear transcription factor, nuclear factor kappa B (NFκB). In turn, NFκB transactivates relevant proinflammatory genes, resulting in an amplification of the inflammatory response. Because this scenario is potentially detrimental to the host, mechanisms exist to limit this amplification. Using an in vitro system that mimics the vascular–interstitial interface during inflammation (cell culture inserts), we provide evidence for the existence of a novel negative feedback mechanism on NFκB activity. We show that the interleukin 1β–induced accumulation of nuclear NFκB in human umbilical vein endothelial cell monolayers is dramatically reduced when polymorphonuclear leukocytes (PMN) are allowed to migrate across these monolayers. This effect does not appear to be due to PMN-derived elastase or nitric oxide. Fixed PMN (adhere but do not migrate) did not affect nuclear NFκB. Furthermore, cross-linking of platelet-endothelial cell adhesion molecule-1 (PECAM-1), but not intercellular adhesion molecule-1, reduces human umbilical vein endothelial cell nuclear NFκB induced by interleukin 1β. Finally, interaction of PMN with PECAM-1–deficient endothelial cells does not reduce nuclear NFκB. These observations indicate that engagement of PECAM-1 by emigrating PMN is a pivotal event in this negative feedback on NFκB activity.
Computational imaging in cell biology
Authors: Eils Roland , Athale Chaitanya
Published: May 2003

Microscopy of cells has changed dramatically since its early days in the mid-seventeenth century. Image analysis has concurrently evolved from measurements of hand drawings and still photographs to computational methods that (semi-) automatically quantify objects, distances, concentrations, and velocities of cells and subcellular structures. Today's imaging technologies generate a wealth of data that requires visualization and multi-dimensional and quantitative image analysis as prerequisites to turning qualitative data into quantitative values. Such quantitative data provide the basis for mathematical modeling of protein kinetics and biochemical signaling networks that, in turn, open the way toward a quantitative view of cell biology. Here, we will review technologies for analyzing and reconstructing dynamic structures and processes in the living cell. We will present live-cell studies that would have been impossible without computational imaging. These applications illustrate the potential of computational imaging to enhance our knowledge of the dynamics of cellular structures and processes.
Neural cell adhesion molecule (NCAM) association with PKCβ2 via βI spectrin is implicated in NCAM-mediated neurite outgrowth
Authors: Leshchyns'ka Iryna , Sytnyk Vladimir , Morrow Jon S. , Schachner Melitta
Published: May 2003

In hippocampal neurons and transfected CHO cells, neural cell adhesion molecule (NCAM) 120, NCAM140, and NCAM180 form Triton X-100–insoluble complexes with βI spectrin. Heteromeric spectrin (αIβI) binds to the intracellular domain of NCAM180, and isolated spectrin subunits bind to both NCAM180 and NCAM140, as does the βI spectrin fragment encompassing second and third spectrin repeats (βI2–3). In NCAM120-transfected cells, βI spectrin is detectable predominantly in lipid rafts. Treatment of cells with methyl-β-cyclodextrin disrupts the NCAM120–spectrin complex, implicating lipid rafts as a platform linking NCAM120 and spectrin. NCAM140/NCAM180–βI spectrin complexes do not depend on raft integrity and are located both in rafts and raft-free membrane domains. PKCβ2 forms detergent-insoluble complexes with NCAM140/NCAM180 and spectrin. Activation of NCAM enhances the formation of NCAM140/NCAM180–spectrin–PKCβ2 complexes and results in their redistribution to lipid rafts. The complex is disrupted by the expression of dominant-negative βI2–3, which impairs binding of spectrin to NCAM, implicating spectrin as the bridge between PKCβ2 and NCAM140 or NCAM180. Redistribution of PKCβ2 to NCAM–spectrin complexes is also blocked by a specific fibroblast growth factor receptor inhibitor. Furthermore, transfection with βI2–3 inhibits NCAM-induced neurite outgrowth, showing that formation of the NCAM–spectrin–PKCβ2 complex is necessary for NCAM-mediated neurite outgrowth.
Modeling the Role of Second Language Proficiency and Topic Familiarity in Second Language Incidental Vocabulary Acquisition Through Reading
Authors: Pulido Diana
Published: May 2003

The study examines the impact of topic familiarity, second language (L2) reading proficiency, and L2 passage sight vocabulary on incidental vocabulary acquisition. Independent variables include (a) a topic familiarity questionnaire, (b) the Adult Basic Learning Examination, Spanish Battery(Karlsen & Gardner, 1990), and (c) a passage sight vocabulary test. A repeated‐measures design was used with a cross‐sectional sample. Participants read narratives (2 more and 2 less familiar) containing nonsense words. Two and 28 days after reading, 2 gain measures were administered: (a) translation production and (b) translation recognition. Analyses reveal robust effects of reading proficiency, differential effects of topic familiarity, and isolated effects of passage sight vocabulary. The discussion concerns the impact of these factors and plausibility of interactive compensatory processing.
Retracted: Impact of Classroom Dynamics on the Effectiveness of Recasts in Second Language Acquisition
Authors: Morris Frank A. , Tarone Elaine E.
Published: May 2003

Forward Links to Citing Articles
 
 
Retraction. Language Learning 56: 1, p xii. Online publication date: 3‐Mar‐2006.

Interpersonal conflict arose in the interactions of three dyads of learners engaged in collaborative work in a foreign language classroom. Results show that although learners corrected each other's errors using recasts, in several cases the learners continued to produce the erroneous form in posttests. Stimulated recall revealed that negative feelings about their conversation partners seemed to have caused some learners to interpret recasts not as helpful corrective feedback, but as criticism and even mockery. The social dynamics of the language classroom may in some cases dramatically alter the way the cognitive processes of attention, or noticing, are deployed in cooperative learning activities in which feedback occurs, and this in turn appears to affect acquisition.
Persistence of Extraordinarily Low Levels of Genetically Homogeneous Human Immunodeficiency Virus Type 1 in Exposed Seronegative Individuals
Authors: Zhu Tuofu , Corey Lawrence , Hwangbo Yon , Lee Jean M. , Learn Gerald H. , Mullins James I. , McElrath M. Juliana
Published: May 2003

Some individuals remain inexplicably seronegative and lack evidence for human immunodeficiency virus type 1 (HIV-1) infection by conventional serologic or virologic testing despite repeated high-risk virus exposures. Here, we examined 10 exposed seronegative (ES) individuals exhibiting HIV-1-specific cytotoxicity for the presence of HIV-1. We discovered HIV-1 DNA in resting CD4
+
T cells (mean, 0.05 ± 0.01 copies per million cells) at multiple visits spanning 69 to 130 weeks in two ES individuals at levels that were on average 10
4
- to 10
6
-fold lower than those of other HIV-1-infected populations reported. Sequences of HIV-1 envelope and
gag
genes remained markedly homogeneous, indicating little to undetectable virus replication. These results provide the evidence for HIV-1 infection in ES individuals below the detection limit of standard assays, suggesting that extraordinary control of infection can occur. The two HIV-infected ES individuals remained healthy and were not superinfected with other HIV-1 strains despite continued high-risk sexual exposures to multiple HIV-infected partners. Understanding the mechanisms that confer diminished replicative capacity of HIV-1 in these hosts is paramount to developing strategies for protection against and control of HIV-1 infection.
Relationship between 3′-Azido-3′-Deoxythymidine Resistance and Primer Unblocking Activity in Foscarnet-Resistant Mutants of Human Immunodeficiency Virus Type 1 Reverse Transcriptase
Authors: Meyer Peter R. , Matsuura Suzanne E. , Zonarich Dianna , Chopra Rahul R. , Pendarvis Eric , Bazmi Holly Z. , Mellors John W. , Scott Walter A.
Published: May 2003

Phosphonoformate (foscarnet) is a pyrophosphate (PPi) analogue and a potent inhibitor of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT), acting through the PPibinding site on the enzyme. HIV-1 RT can unblock a chain-terminated DNA primer by phosphorolytic transfer of the terminal residue to an acceptor substrate (PPior a nucleotide such as ATP) which also interacts with the PPibinding site. Primer-unblocking activity is increased in mutants of HIV-1 that are resistant to the chain-terminating nucleoside inhibitor 3′-azido-3′-deoxythymidine (AZT). We have compared the primer-unblocking activity for HIV-1 RT containing various foscarnet resistance mutations (K65R, W88G, W88S, E89K, S117T, Q161L, M164I, and the double mutant Q161L/H208Y) alone or in combination with AZT resistance mutations. The level of primer-unblocking activity varied over a 150-fold range for these enzymes and was inversely correlated with foscarnet resistance and directly correlated with AZT resistance. Based on published crystal structures of HIV-1 RT, many of the foscarnet resistance mutations affect residues that do not make direct contact with the catalytic residues of RT, the incoming deoxynucleoside triphosphate (dNTP), or the primer-template. These mutations may confer foscarnet resistance and reduce primer unblocking by indirectly decreasing the binding and retention of foscarnet, PPi, and ATP. Alternatively, the binding position or orientation of PPi, ATP, or the primer-template may be changed in the mutant enzyme complex so that molecular interactions required for the unblocking reaction are impaired while dNTP binding and incorporation are not.
Boudicca
, a Retrovirus-Like Long Terminal Repeat Retrotransposon from the Genome of the Human Blood Fluke
Schistosoma mansoni
Authors: Copeland Claudia S. , Brindley Paul J. , Heyers Oliver , Michael Scott F. , Johnston David A. , Williams David L. , Ivens Alasdair C. , Kalinna Bernd H.
Published: May 2003

The genome of
Schistosoma mansoni
contains a proviral form of a retrovirus-like long terminal repeat (LTR) retrotransposon, designated
Boudicca
. Sequence and structural characterization of the new mobile genetic element, which was found in bacterial artificial chromosomes prepared from
S. mansoni
genomic DNA, revealed the presence of three putative open reading frames (ORFs) bounded by direct LTRs of 328 bp in length. ORF1 encoded a retrovirus-like major homology region and a Cys/His box motif, also present in Gag polyproteins of related retrotransposons and retroviruses. ORF2 encoded enzymatic domains and motifs characteristic of a retrovirus-like polyprotein, including aspartic protease, reverse transcriptase, RNase H, and integrase, in that order, a domain order similar to that of the
gypsy
/
Ty3
retrotransposons. An additional ORF at the 3′ end of the retrotransposon may encode an envelope protein. Phylogenetic comparison based on the reverse transcriptase domain of ORF2 confirmed that
Boudicca
was a
gypsy
-like retrotransposon and showed that it was most closely related to
CsRn1
from the Oriental liver fluke
Clonorchis sinensis
and to
kabuki
from
Bombyx mori
. Bioinformatics approaches together with Southern hybridization analysis of genomic DNA of
S. mansoni
and the screening of a bacterial artificial chromosome library representing ≈8-fold coverage of the
S. mansoni
genome revealed that numerous copies of
Boudicca
were interspersed throughout the schistosome genome. By reverse transcription-PCR, mRNA transcripts were detected in the sporocyst, cercaria, and adult developmental stages of
S. mansoni
, indicating that
Boudicca
is actively transcribed in this trematode.
Gene Expression Profiling of the Cellular Transcriptional Network Regulated by Alpha/Beta Interferon and Its Partial Attenuation by the Hepatitis C Virus Nonstructural 5A Protein
Authors: Geiss Gary K. , Carter Victoria S. , He Yupeng , Kwieciszewski Bartlomiej K. , Holzman Ted , Korth Marcus J. , Lazaro Catherine A. , Fausto Nelson , Bumgarner Roger E. , Katze Michael G.
Published: May 2003

Alpha/beta interferons (IFN-α/β) induce potent antiviral and antiproliferative responses and are used to treat a wide range of human diseases, including chronic hepatitis C virus (HCV) infection. However, for reasons that remain poorly understood, many HCV isolates are resistant to IFN therapy. To better understand the nature of the cellular IFN response, we examined the effects of IFN treatment on global gene expression by using several types of human cells, including HeLa cells, liver cell lines, and primary fetal hepatocytes. In response to IFN, 50 of the approximately 4,600 genes examined were consistently induced in each of these cell types and another 60 were induced in a cell type-specific manner. A search for IFN-stimulated response elements (ISREs) in genomic DNA located upstream of IFN-stimulated genes revealed both previously identified and novel putative ISREs. To determine whether HCV can alter IFN-regulated gene expression, we performed microarray analyses on IFN-treated HeLa cells expressing the HCV nonstructural 5A (NS5A) protein and on IFN-treated Huh7 cells containing an HCV subgenomic replicon. NS5A partially blocked the IFN-mediated induction of 14 IFN-stimulated genes, an effect that may play a role in HCV resistance to IFN. This block may occur through repression of ISRE-mediated transcription, since NS5A also inhibited the IFN-mediated induction of a reporter gene driven from an ISRE-containing promoter. In contrast, the HCV replicon had very little effect on IFN-regulated gene expression. These differences highlight the importance of comparing results from multiple model systems when investigating complex phenomena such as the cellular response to IFN and viral mechanisms of IFN resistance.
Enhancement of Recombinant Adeno-Associated Virus Type 2-Mediated Transgene Expression in a Lung Epithelial Cell Line by Inhibition of the Epidermal Growth Factor Receptor
Authors: Smith Andrew D. , Collaco Roy F. , Trempe James P.
Published: May 2003

Recombinant adeno-associated viruses (rAAVs) have attracted considerable interest as gene delivery systems because they show long-term expression in vivo and transduce numerous cell types. Limitations to successful gene transduction from rAAVs have prompted investigations of a variety of treatments to enhance transgene expression from rAAV vectors. Tyrphostin-1, an epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor, dramatically enhances rAAV transgene expression. Elegant studies have demonstrated that a single-strand D-sequence-binding protein (ssDBP) is phosphorylated by EGFR and binds to the D sequence element in the AAV terminal repeat (TR). Binding of the Tyr-phosphorylated ssDBP prevents conversion of single-stranded vector DNA to a double-strand conformation. We observed dramatic increases in transgene expression in lung epithelial cells (IB3) with tyrphostin treatment. Gel shift analysis of ssDBP revealed that its DNA binding characteristics were unchanged after tyrphostin treatment or adenovirus infection. Tyrphostin stimulated rAAV transgene expression to a greater extent than adenovirus coinfection. Southern hybridizations revealed that the vector DNA remained in the single-strand conformation in tyrphostin-treated cells but double-stranded replicative form monomer DNA was most abundant in adenovirus-infected cells. Northern analyses revealed that tyrphostin treatment enhanced mRNA accumulation more than in adenovirus-infected cultures even though replicative form DNA was undetectable. Analysis of the JNK, ERK, and p38K mitogen-activated protein kinase pathways revealed that tyrphostin treatment stimulated the activity of JNK and p38K. Our data suggest that tyrphostin-induced alteration of stress response pathways results in dramatic enhancement of transcription on linear vector DNA templates in the IB3 cell line. These results expand the downstream targets of the EGFR in regulating rAAV transduction.
Clearance of a Productive Lentivirus Infection in Calves Experimentally Inoculated with Caprine Arthritis-Encephalitis Virus
Authors: Morin Thierry , Guiguen François , Bouzar Baya Amel , Villet Stéphanie , Greenland Timothy , Grezel Délphine , Gounel Françoise , Gallay Kathy , Garnier Céline , Durand Jitka , Alogninouwa Théodore , Mselli-Lakhal Laïla , Mornex Jean-François , Chebloune Yahia
Published: May 2003

Lentiviruses have long been considered host-specific pathogens, but several recent observations demonstrated their capacity to conquer new hosts from different species, genera, and families. From these cross-species infections emerged new animal and human infectious diseases. The successful colonization and adaptation of a lentivirus to a nonnatural host depends on unspecific and specific host barriers. Some of those barriers exert a relative control of viral replication (i.e., cytotoxic T-lymphocyte response, viral inhibitory factors), but none of them was found able to totally clear the infection once the retrovirus is fully adapted in its host. In this study we examined the evolution of the host-lentivirus interactions occurring in an experimental animal model of cross-species infection in order to analyze the efficiency of those barriers in preventing the establishment of a persistent infection. Five newborn calves were inoculated with caprine arthritis-encephalitis virus (CAEV), and the evolution of infection was studied for more than 12 months. All the animals seroconverted in the first 0.75 to 1 month following the inoculation and remained seropositive for the remaining time of the experiment. Viral infection was productive during 4 months with isolation of replication competent virus from the blood cells and organs of the early euthanized animals. After 4 months of infection, neither replication-competent virus nor virus genome could be detected in blood cells or in the classical target organs, even after an experimental immunosuppression. No evidence of in vitro restriction of CAEV replication was observed in cells from tissues explanted from organs of these calves. These data provide the demonstration of a natural clearance of lentivirus infection following experimental inoculation of a nonnatural host, enabling perspectives of development of new potential vaccine strategies to fight against lentivirus infections.
Activation of Adenovirus Early Promoters and Lytic Phase in Differentiated Strata of Organotypic Cultures of Human Keratinocytes
Authors: Noya Francisco , Balagué Cristina , Banerjee N. Sanjib , Curiel David T. , Broker Thomas R. , Chow Louise T.
Published: May 2003

Human oncolytic adenoviruses have been used in clinical trials targeting cancers of epithelial origin. To gain a better understanding of the infectious cycle of adenovirus in normal human squamous tissues, we examined the viral infection process in organotypic cultures of primary human keratinocytes. We show that for the infection to occur, wounding of the epithelium is required. In addition, infection appears to initiate at the basal or parabasal cells that express the high-affinity coxsackievirus-adenovirus receptor, CAR, whereas the productive phase takes place in differentiated cells. This is due, at least in part, to the differentiation-dependent activation of the E1A and E2A early promoters and E4 promoters. We also show that adenovirus infection triggers a response mediated by the abnormal accumulation of cyclin E and p21cip1 proteins similar to the one previously observed in human papillomavirus-infected tissues. However, the virus seems to be able to overcome it, at least partially.
Excretion of Wild-Type and Vaccine-Derived Poliovirus in the Feces of Poliovirus Receptor-Transgenic Mice
Authors: Boot Hein J. , Kasteel Daniella T. J. , Buisman Anne-Marie , Kimman Tjeerd G.
Published: May 2003

The emergence of circulating vaccine-derived poliovirus (cVDPV) strains in suboptimally vaccinated populations is a serious threat to the global poliovirus eradication. The genetic determinants for the transmissibility phenotype of polioviruses, and in particularly of cVDPV strains, are currently unknown. Here we describe the fecal excretion of wild-type poliovirus, oral polio vaccine, and cVDPV (Hispaniola) strains after intraperitoneal injection in poliovirus receptor-transgenic mice. Both the pattern and the level of fecal excretion of the cVDPV strains resemble those of wild-type poliovirus type 1. In contrast, very little poliovirus was present in the feces after oral polio vaccine administration. This mouse model will be helpful in elucidating the genetic determinants for the high fecal-oral transmission phenotype of cVDPV strains.
Viral Internal Ribosome Entry Site Structures Segregate into Two Distinct Morphologies
Authors: Beales Lucy P. , Holzenburg Andreas , Rowlands David J.
Published: May 2003

An increasing number of viruses have been shown to initiate protein synthesis by a cap-independent mechanism involving internal ribosome entry sites (IRESs). Predictions of the folding patterns of these RNA motifs have been based primarily on sequence and biochemical analyses. Biophysical confirmation of the models has been achieved only for the IRES of hepatitis C virus (HCV), which adopts an open structure consisting of two major stems. We have conducted an extensive comparison of flavivirus and picornavirus IRES elements by negative stain transmission electron microscopy. All of the flavivirus IRESs we examined (those of GB virus-B, GB virus-C, and classical swine fever virus) fold to give a structure similar to that of the HCV IRES, as does an IRES recently found on mRNA encoded by human herpesvirus 8. The larger picornavirus IRESs (those of foot-and-mouth disease virus, rhinovirus, encephalomyocarditis virus, and hepatitis A virus) are morphologically similar, comprising a backbone with two protruding stems, and distinct from the flavivirus IRESs.