Sex-Related Effect of Aging in Gingival Gamma-Delta T Cells

Aging affects the number and function of gamma-delta (γδ) T cells in a tissue-specific manner, modifying the risk for inflammatory disease. These aging-related γδT-cell variations in gingival tissues that could increase the risk for inflammation and periodontal disease remain unknown. Here we sought to identify quantitative and qualitative variations in gingival γδT cells associated with aging that could have an impact in oral immunoinflammatory responses. For this, gingival tissues from young (4 mo) and aged (24 mo) male and female mice were collected and analyzed by flow cytometry. Cell suspensions were stimulated and stained with eFluor450 (cell viability), anti-CD45 (hematopoietic cells), anti-CD3 (lymphocytes), anti-TCRγδ (γδT cells), anti-IL-15rα (cell proliferation), and anti-Notch-3 (senescence marker). Detection of intracellular cytokines IL-17A and interferon γ (IFNγ) was performed. Gingival expression of specific γ- and δ-chains and cytokines was evaluated by quantitative reverse transcription polymerase chain reaction. A significantly higher number of IL-17A-producing γδT cells and IL-17A expression levels were observed in gingival tissues from aged females but not males. Similarly, the number of gingival Notch-3+ γδT cells increased with aging only in females. IL-15rα was not detected in gingival γδT cells. Chains γ1, 2, 4, 5, 6, and 7 as well as δ1, 2, 4, and 6 were detected. Detection levels of all γ chains except γ1 as well as δ1 and δ2 changed with aging in males, females, or both. Interestingly, number of IL-17A-producing conventional T cells similarly increased with aging only in females. Both sexes showed increased IFNγ+ conventional T-cell numbers with aging; however, it reached significance only in females. In conclusion, the number of gingival IL-17A-producing γδT cells and IL-17A expression increase naturally with aging specifically in females. This sexual dimorphism in gingival γδT and conventional Th17 cell numbers and phenotypes suggests distinct aging-related mechanisms of periodontitis in males and females.

Pre-Flight Calibration of the Mars 2020 Rover Mastcam Zoom (Mastcam-Z) Multispectral, Stereoscopic Imager

The NASA Perseverance rover Mast Camera Zoom (Mastcam-Z) system is a pair of zoomable, focusable, multi-spectral, and color charge-coupled device (CCD) cameras mounted on top of a 1.7 m Remote Sensing Mast, along with associated electronics and two calibration targets. The cameras contain identical optical assemblies that can range in focal length from 26 mm ( 25.5 ∘ × 19.1 ∘ FOV ) to 110 mm ( 6.2 ∘ × 4.2 ∘ FOV ) and will acquire data at pixel scales of 148-540 μm at a range of 2 m and 7.4-27 cm at 1 km. The cameras are mounted on the rover's mast with a stereo baseline of 24.3 ± 0.1  cm and a toe-in angle of 1.17 ± 0.03 ∘ (per camera). Each camera uses a Kodak KAI-2020 CCD with 1600 × 1200 active pixels and an 8 position filter wheel that contains an IR-cutoff filter for color imaging through the detectors' Bayer-pattern filters, a neutral density (ND) solar filter for imaging the sun, and 6 narrow-band geology filters (16 total filters). An associated Digital Electronics Assembly provides command data interfaces to the rover, 11-to-8 bit companding, and JPEG compression capabilities. Herein, we describe pre-flight calibration of the Mastcam-Z instrument and characterize its radiometric and geometric behavior. Between April 26 t h and May 9 t h , 2019, ∼45,000 images were acquired during stand-alone calibration at Malin Space Science Systems (MSSS) in San Diego, CA. Additional data were acquired during Assembly Test and Launch Operations (ATLO) at the Jet Propulsion Laboratory and Kennedy Space Center. Results of the radiometric calibration validate a 5% absolute radiometric accuracy when using camera state parameters investigated during testing. When observing using camera state parameters not interrogated during calibration (e.g., non-canonical zoom positions), we conservatively estimate the absolute uncertainty to be < 10 % . Image quality, measured via the amplitude of the Modulation Transfer Function (MTF) at Nyquist sampling (0.35 line pairs per pixel), shows MTF Nyquist = 0.26 - 0.50 across all zoom, focus, and filter positions, exceeding the > 0.2 design requirement. We discuss lessons learned from calibration and suggest tactical strategies that will optimize the quality of science data acquired during operation at Mars. While most results matched expectations, some surprises were discovered, such as a strong wavelength and temperature dependence on the radiometric coefficients and a scene-dependent dynamic component to the zero-exposure bias frames. Calibration results and derived accuracies were validated using a Geoboard target consisting of well-characterized geologic samples.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s11214-021-00795-x.

Epitaxial thin films of pyrochlore iridate Bi2+xIr2-yO7-δ: structure, defects and transport properties

While pyrochlore iridate thin films are theoretically predicted to possess a variety of emergent topological properties, experimental verification of these predictions can be obstructed by the challenge in thin film growth. Here we report on the pulsed laser deposition and characterization of thin films of a representative pyrochlore compound Bi₂Ir₂O₇. The films were epitaxially grown on yttria-stabilized zirconia substrates and have lattice constants that are a few percent larger than that of the bulk single crystals. The film composition shows a strong dependence on the oxygen partial pressure. Density-functional-theory calculations indicate the existence of Bi_Ir antisite defects, qualitatively consistent with the high Bi: Ir ratio found in the films. Both Ir and Bi have oxidation states that are lower than their nominal values, suggesting the existence of oxygen deficiency. The iridate thin films show a variety of intriguing transport characteristics, including multiple charge carriers, logarithmic dependence of resistance on temperature, antilocalization corrections to conductance due to spin-orbit interactions, and linear positive magnetoresistance.

p-Type transition-metal doping of large-area MoS2 thin films grown by chemical vapor deposition

Two-dimensional transition metal dichalcogenides (e.g. MoS₂) have recently emerged as a promising material system for electronic and optoelectronic applications. A major challenge for these materials, however, is to realize bipolar electrical transport properties (i.e. both p-type and n-type conduction), which is critical for enhancing device performance and functionalities. Here, we demonstrate the transition metal zinc as a p-type dopant in the otherwise n-type MoS₂, through systematic characterizations of large area Zn-doped MoS₂ thin films grown by a one-step chemical vapor deposition (CVD) approach. Raman characterization and X-ray photoelectron spectroscopy studies identified millimeter-scale, monolayer films with 1-2% Zn as dopants. Zinc doping suppresses n-type conductivity in MoS₂ and shifts its Fermi level downwards. The stability and p-type nature of Zn dopants were further confirmed by density-functional-theory calculations of formation energies and electronic band structures. The electrical transport properties of Zn-MoS₂ films can be influenced by stoichiometry, and p-type gate transfer characteristics were realized by thermal treatment under a sulfur atmosphere. Our work highlights transition-metal doping followed by sulfur vacancy elimination in CVD grown films as a promising route for achieving large area p-type transition metal dichalcogenide films that are essential for practical applications in electronics and optoelectronics.

Cryptococcus gattii infections on Vancouver Island, British Columbia, Canada: emergence of a tropical fungus in a temperate environment

BACKGROUND

Cryptococcus gattii causes disease among immunocompetent individuals in the tropics and subtropics. We document the appearance of C. gattii infections on Vancouver Island (VI), a temperate region, and discuss reasons for this emergence.

METHODS

Data on Cryptococcus hospitalizations for the calendar years 1995 through 2004 were reviewed. Viable historic isolates stored at the provincial public health laboratory between 1987 and 2000 were serotyped. Human cases were mapped by place of residence.

RESULTS

Cryptococcosis among HIV negative individuals diagnosed on VI increased sharply after 1999. C. gattii was not detected in stored isolates prior to 1999. C. gattii cases lived in a specific biogeoclimatic zone on VI. Higher rates of illness were associated with exposure to the central region of VI.

CONCLUSIONS

The emergence of C. gattii in a temperate region is unprecedented. Clinicians should consider C. gattii in the differential diagnosis of individuals who travelled to certain areas in British Columbia.

Clinical evaluation of nitric oxide responses to anti-VEGF therapy with bevacizumab

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Background: Anti-vascular endothelial growth factor (anti-VEGF) therapy has been linked to hypertension (HTN) and arterial thrombo-embolic events that may involve changes in nitric oxide (NO) bioavailability. Methods: 25 patients (pts) with advanced cancer, normal renal function and blood pressure (BP), no increased risks for anti-VEGF toxicities, and not on medications known to confound biomarker studies (including anti-hypertensives) were treated with bevacizumab (BV) 15mg/kg d1, then 10mg/kg q2 week. Prior to biomarker assessment, all patients were placed on a calorie-, nitrate-, and salt-restricted diet for 72 hr. All measures were taken pre-treatment (preRx) and on day 28 of treatment (onRx). Dependant variables included; a) Brachial artery reactivity (BAR) following hyperemic flow stimulus (endothelium-dependent) and sub-lingual nitroglycerine (NTG; endothelium-independent); b) exhaled and plasma/urine total NO2/NO3 using chemiluminescence (Sievers 280NOA) with either KI or VCl3 in HCl as the reductants; c) blood pressure. Additionally, we measured multiple regulators of vascular tone and injury. Comparisons were analyzed using Spearman signed rank tests. Results: Of 25 pts (16 F, 9 M) treated, 21 patients were fully evaluable. Significant changes or strong trends were observed upon comparing preRx vs. onRx for BP (SBP +12.4, DBP +5.6, MAP +7.9 mm Hg), and flow-mediated BAR (-2.0%) with no changes in hyperemic flow/shear stimulus or smooth muscle function (BAR NTG), indicating a decrease in brachial artery endothelial responsiveness. Exhaled NO decreased (-0.8% d1vs d28 and -0.6% pre/post infusion day1). Measurement and data analysis of urinary/plasma NO2/NO3, as well as angiogenic markers, are almost complete and will be reported. Conclusions: After one month of treatment, BV increased BP and decreased endothelium- dependent BAR and exhaled NO, suggesting potentially broad, mechanism-based effects on NO bioavailability in patients.

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Deposition in boreal forests in relation to type, size, number and placement of collectors

Open precipitation and throughfall was collected at a Norway spruce stand in Finland using funnel-type collectors and at a black spruce stand in Canada using trough-type collectors. The presence or absence of a rim on the funnel, funnel diameter (9, 14 and 20 cm) and length of sampling period (1, 2 and 4 weeks) on monthly values were evaluated at the Norway spruce stand, and the number of collectors required for defined levels of accuracy and precision of throughfall loads to be reached and the influence of the spatial arrangement of collectors on solute concentrations was studied at both stands. The presence of a rim had no significant effect on open precipitation and throughfall amounts, but did on throughfall DOC, Ca(2+), Mg(2+), K(+), Na(+) and Cl(-) ion loads. Deposition loads increased with decreasing funnel diameter; for open precipitation, this was due to increased catch efficiency while for throughfall the increase was attributed to canopy interaction and leaching of litter trapped in the collectors. Calculated monthly H(+) loads decreased and those for all other constituents increased with collection period length. Using 15 collectors at the Norway spruce stand would allow throughfall loads to be determined to within 20% of the true mean weekly value with a confidence level of 95% for most solute, but not for NH(4) (+)-N, NO(3) (-)-N, Mg(2+) and SO(4) (2-)-S. Using 15 trough collectors, the same confidence level at the more heterogeneous black spruce stand would only be achieved for H(+), Cl(-), DOC and SO(4) (2-)-S loads. In both stands, using either random or systematic placements of throughfall collectors gave similar results.

Medication non-adherence in women with fibromyalgia

OBJECTIVE

To identify the determinants of medication non-adherence in women with fibromyalgia (FM).

METHODS

Participants included 10 rheumatologists and 127 women recruited from tertiary care hospitals and the community. Demographic, clinical and psychosocial characteristics and patient-physician discordance were assessed at the baseline visit. Non-adherence was assessed 2 weeks later. Multivariable generalized estimating equations were used to identify determinants of non-adherence to medication.

RESULTS

The average age of the women was 50.4 (s.d. 10.5) yr and the mean disability score was 60.3 (16.0) yr. Sixty (47.2%) women were non-adherent to medication; 20 (33.3%) of these were intentionally non-adherent, 24 (40.0%) were unintentionally non-adherent, and the remaining subjects were both. Overall non-adherence was predicted by higher patient-physician discordance. Unintentional non-adherence was predicted by community subjects, not being under a rheumatologist's care, less disease activity, less use of instrumental coping, and higher patient-physician discordance. Intentional non-adherence was predicted by shorter duration under a rheumatologist's care and higher patient-physician discordance.

CONCLUSION

The therapeutic relationship, in addition to clinical and psychosocial characteristics, influenced non-adherence to medication.

A randomised controlled clinical trial of the efficacy of family-based direct observation of anti-tuberculosis treatment in an urban, developed-country setting

SETTING

A randomised, controlled clinical trial of the effectiveness of a family-based programme of directly observed treatment (DOT) for tuberculosis.

METHODS

TB patients seen in Victoria, Australia, were randomly allocated to DOT observed by a family member (FDOT), or to standard supervised but non-observed therapy (ST). The outcome measure was compliance, measured by blinded testing of isoniazid levels in urine. An intention-to-treat analysis was used.

RESULTS

Of 173 patients, 87 were allocated to FDOT and 86 to ST. Only 58% in the FDOT group were able to receive FDOT, the major reason being living alone and not having a family member to observe treatment. The rate of non-compliance was 24% (41/173), with no significant difference between FDOT (22/87) and ST (19/86). No clinical or socio-demographic variable predicted compliance.

CONCLUSIONS

We were unable to demonstrate a benefit of FDOT in an urban, industrialised country setting. FDOT may be more appropriate in developing countries, where extended family support is often available and the burden of TB is much higher. Poor compliance and the difficulty in predicting non-compliance shown in this study highlights the need for DOT for all TB patients.

Epidemiology of salmonellosis in California, 1990-1999: morbidity, mortality, and hospitalization costs

Salmonella is a common cause of bacterial foodborne illness in the United States. The epidemiology and costs of nontyphoidal salmonellosis in California from 1990 through 1999 are described using surveillance, hospitalization, and death data. Trends in Salmonella rates and factors associated with prolonged hospitalization were evaluated using Poisson and linear regression models, respectively. There were 56,660 reported cases, 11,102 hospitalizations, and 74 deaths attributed to Samonella. Reported case and hospital discharge rates have decreased since 1996. Among reported cases, infants had the highest rate (121 cases per 10(5) person-years), followed by children 1-4 years of age (40 cases per 10(5) person-years). The highest hospitalization rates were among the elderly and young children. Most deaths occurred among persons aged 65 or more years (59%). Among hospitalizations, gastroenteritis (61%) and septicemia (23%) were the most common Salmonella diagnoses. Salmonella pneumonia patients were the oldest (median age, 55 years) and Salmonella meningitis patients the youngest (median age, 0.3 years). These two diagnoses were the costliest, approaching 30,000 dollars (median) per hospitalization. Having an acquired immunodeficiency syndrome diagnosis or multiple Salmonella diagnoses was independently associated with prolonged hospitalization. The estimated 10-year hospitalization costs for Salmonella were $200 million. Salmonellosis is a costly disease that disproportionately affects the young and elderly.

Mycobacterium ulcerans infection diagnosed by polymerase chain reaction

Mycobacterium ulcerans infection is the third most important mycobacterial infection world-wide affecting immunocompetent individuals and causes chronic progressive skin ulcers. It has been described in many different regions world-wide. The diagnosis of M. ulcerans infection is often delayed because the diagnosis is difficult to make when new cases appear outside known endemic areas. However, molecular methods are now available to diagnose and distinguish M. ulcerans from other mycobacteria, allowing rapid diagnosis. Presented here is the case of a previously well girl from Townsville, Queensland, with extensive M. ulcerans infection involving the elbow joint, triceps tendon and underlying bone. Rapid diagnosis by polymerase chain reaction confirmed M. ulcerans infection. This is the first known case of M. ulcerans infection from Townsville in over 25 years, highlighting the changing epidemiology of this disease.

Severe Bordetella holmesii infection in a previously healthy adolescent confirmed by gene sequence analysis

We describe an immunocompetent adolescent who presented with exceptionally severe Bordetella holmesii infection, including previously undescribed manifestations. Sequelae included a severe restrictive lung defect due to pulmonary fibrosis.

Spatial and temporal emergence of high proliferative potential hematopoietic precursors during murine embryogenesis

During mouse embryogenesis, two waves of hematopoietic progenitors originate in the yolk sac. The first wave consists of primitive erythroid progenitors that arise at embryonic day 7.0 (E7.0), whereas the second wave consists of definitive erythroid progenitors that arise at E8.25. To determine whether these unilineage hematopoietic progenitors arise from multipotential precursors, we investigated the kinetics of high proliferative potential colony-forming cells (HPP-CFC), multipotent precursors that give rise to macroscopic colonies when cultured in vitro. No HPP-CFC were found at presomite stages (E6.5-E7.5). Rather, HPP-CFC were detected first at early somite stages (E8.25), exclusively in the yolk sac. HPP-CFC were found subsequently in the bloodstream at higher levels than the remainder of the embryo proper. However, the yolk sac remains the predominant site of HPP-CFC expansion (>100-fold) until the liver begins to serve as the major hematopoietic organ at E11.5. On secondary replating, embryonic HPP-CFC give rise to definitive erythroid and macrophage (but not primitive erythroid) progenitors. Our findings support the hypothesis that definitive but not primitive hematopoietic progenitors originate from yolk sac-derived HPP-CFC during late gastrulation.

Randomized, controlled trial comparing once daily and three times daily gentamicin in children with urinary tract infections

OBJECTIVE

To undertake population pharmacokinetic modeling and to determine the safety and efficacy of once daily (OD) gentamicin dosing in children with severe urinary tract infections (UTI).

METHODS

An open, randomized, controlled trial comparing OD with three times daily (TD) gentamicin dosing in hospitalized children ages 1 month to 12 years with UTI. Daily doses (milligrams per kg per day) of gentamicin in both groups were 7.5 (<5 years old), 6.0 (5 to 10 years old) and 4.5 (>10 years old).

RESULTS

There were 179 children enrolled (90 OD, 89 TD). Baseline clinical characteristics and pathogens were similar, except that circulatory compromise and renal cortical scintigraphic defects were more common in the OD group. Median gentamicin treatment durations were 3.0 (OD) and 2.7 (TD) days. Mean peak gentamicin concentrations were 17.3 (OD) vs. 6.4 (TD) mg/l; 99% of peak concentrations were >7 mg/l in the OD group whereas 16% of peak concentrations were <5 mg/l in the TD group. Mean trough concentrations were 0.35 (OD) vs. 0.55 (TD) mg/l. In the OD group 4% of trough concentrations were > or = 2 mg/l, whereas in the TD group only 0.7% were > or = 2 mg/l. Age or prior elevated peak concentrations did not predict high trough concentrations. Population pharmacokinetic modeling of the data fitted a one-compartment model with first order elimination. There were no clinical or bacteriologic failures. The two disease-related complications were confined to the OD group. No nephro- or ototoxicity was identified.

CONCLUSIONS

With age-appropriate dosing and measurement of serum trough concentrations before the second dose, OD gentamicin is safe and effective for the treatment of UTI requiring parenteral treatment in children aged 1 month to 12 years.

The importance of leaching from litter collected in litterfall traps

Litterfall (LF) is usually collected by means of open traps. However, this litter will be subject to leaching by the throughfall which passes through the accumulated litter in the traps. The nutrients lost during this leaching are not taken into account in the calculation of LF nutrient fluxes. We report the results from a 2-month (August-September) study carried out in 8 northern coniferous forest stands to assess the possible importance of leaching from litter in LF traps. Compared to throughfall (TF), the litterfall leachate (LFLgross), which includes a throughfall component, had significantly (p < 0.05) higher concentrations and fluxes of Ca, Mg, Na and S. The average net LFL (i.e., LFLnet = LFLgross - TF) fluxes were 21 (Ca), 7 (Mg), 57 (K), 10 (Na), 10 (N), and 19 (S) mg m-2 mo-1. LFLnet accounted for 42%, 37% and 50% of the LFLgross flux, and for 91%, 51% and 49% of the total litterfall flux (i.e., LF + LFLnet) of Na, S and K, respectively. For Ca, Mg and N, the LFLnet flux accounted for 64%, 58% and 29% of the LFLgross flux, and for < 14% of the total litterfall flux. Compared to TF, LF was the dominant return pathway for Ca, Mg and N to the forest floor regardless of whether LFLnet was included or not. However, for K and S, taking LFLnet into account determined whether TF or LF was the dominant pathway. TF remained the dominant pathway for Na even when LFLnet was included.

Heavy metal budgets for two headwater forested catchments in background areas of Finland

Mean annual (1994-1996) budgets for Cd, Cu, Ni, Pb and Zn at two background, forested catchments, VK and HJ, in Finland are presented. Budgets for plots (VK3, HJ1 and HJ4) included throughfall (TF), litterfall (LF) and soil leaching fluxes, and for catchments terrestrial retention and leaching and lake sedimentation fluxes. Total deposition (TD) loads were relatively low (Cd < 0.1, Cu < 2, Ni < 1, Pb < 3 and Zn < 5 mg m-2 year-1) and that even in these areas almost half of the TD was in the form of dry deposition. Retention of TD within catchments was > or = 77% for all metals, except for Ni at VK (54%). For Cu and Pb, the retention was 94-97%. Most of the retention (74-97%) took place in the terrestrial part of the catchment, lake sedimentation accounting for the remainder. Plot-scale soil leaching fluxes at 40 cm of Cd, Cu (VK3) and Ni (VK3) were greater (> or = 100%) than TD inputs. Most of the catchment retention must therefore have taken place either deeper in the soil or in the lowland peatland areas. The humus layer was particularly effective in retaining Cu and Cd (65-81% and 51-78% of total inputs to the forest floor (TF + LF)). The retention of Pb by the humus layer was less than expected (26-54% of TF + LF). Litterfall was a particularly important internal flux for Zn.

A community rheumatology practice offers an educational experience comparable to that of a university tertiary care center

OBJECTIVE

To compare the teaching value of rheumatology patients seen in either a community rheumatology practice or in a tertiary care university center.

METHODS

Consecutive patients seen at the 2 sites over a one month period were assessed for rheumatology diagnosis, complexity of rheumatologic disease, and treatments received, including number of interventions performed. The overall pedagogic value of the encounter was rated by the rheumatologist for both medical students and postgraduate trainees.

RESULTS

Rheumatology patients were comparable at the 2 sites for overall pedagogic value, rheumatology diagnostic category, and complexity of disease. At the community site, however, there were more patients evaluated, more procedures performed, and more new treatments introduced.

CONCLUSION

Contrary to current perceptions, comparable pedagogic value of rheumatology patients was observed outside a tertiary care setting. In the changing climate of education, and considering resource limitations that influence current rheumatology practice, community based rheumatology has the potential to offer a valuable educational experience.

Is the processing of words during eye fixations in reading strictly serial?

Extant models of oculomotor control during reading maintain that allocation of attention confines word recognition to one (target) word at a time, and that an eye movement to a new (posttarget) word is computed before attention is shifted to it. To test these assumptions, properties of the posttarget's preview were manipulated during the fixation of the preceding target word. The main results revealed longer target viewing durations when the posttarget preview was visually distinctive or when it was orthographically illegal. The meaning of posttarget text did not affect initial target word reading, although it affected the time spent rereading the target. To account for these findings, extant attention-shift models must assume that readers obtain at least visuospatial and orthographic information from a parafovelly visible word before it is attended. This view has shortcomings, however, and several considerations favor less restrictive model assumptions according to which attention can be allocated to more than one word at a time.

A rash of exanthems. How they affect children and pregnant women

BACKGROUND

Viral exanthems are a common problem for children, particularly during preschool years. Many of these infections have a dramatic impact on siblings, parents and other contacts. There may also be particular ramifications for pregnant contacts.

OBJECTIVE

To discuss some of the most common viral exanthems affecting children, in terms of the epidemiology, clinical features, diagnosis, and the management of both the patient and the contacts.

DISCUSSION

Recommendations are made for measles, rubella, parvovirus and varicella regarding immunisations, use of immunoglobulin, serological diagnosis and management of pregnant contacts.

Attentional function in secondary school students receiving isoniazid prophylaxis for tuberculosis infection

Reports have suggested that isoniazid treatment may be associated with poor concentration and subtle reduction in memory. This study examines attentional function and processing speed in a group of 25 adolescents who received isoniazid prophylaxis for at least 6 months. As adolescents often face major educational assessment milestones, such cognitive side effects may have important implications. Participants were assessed before treatment, 1 month into treatment and at least 1 week after treatment cessation. Measures included the Paced Auditory Serial Addition Test and subtests of the appropriate Wechsler scale sensitive to attention and speed of information processing. Isoniazid does not appear to cause significant adverse effects on attentional function in adolescents.