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Biomedical subjects

S D Smith

Publications and source records attributed to S D Smith.

At least 19 recordsLinked to original sources
PubMed2006

Possible involvement of alpha-2A adrenergic receptors in attention deficit hyperactivity disorder: radioligand binding and polymorphism studies.

Neuropharmacological and genetic association studies have implicated norepinephrine and adrenergic receptors in the pathogenesis of ADHD. The purpose of this study was to compare genetic association studies of three polymorphisms of the alpha-2A adrenergic receptor gene (ADRA2A) with radioligand binding studies of the alpha-2A adrenergic receptor protein in platelets from a sample of children without or with ADHD. The pediatric subjects ranged from 6 to 18 years of age. A thorough clinical assessment of each child resulted in one of the following DSM-IV ADHD diagnoses: inattentive, hyperactive/impulsive, combined, or no ADHD. No significant linkage was found between the ADRA2A polymorphisms (MspI, HhaI, and DraI) and any of the phenotypes tested. Association analysis, however, did detect significant linkage disequilibrium for the DraI polymorphism. Association was also evaluated considering the three ADRA2A single nucleotide polymorphisms as haplotypes. The HhaI-DraI and the MspI-HhaI-DraI haplotypes were significantly associated with ADHD. The platelet alpha-2 adrenergic receptor density did not differ between children without or with ADHD. The affinity of the receptor for the radioligand however, differed significantly between those without and with ADHD. In addition, there were some significant correlations between binding parameters and severity of ADHD in this well-characterized clinical population, and significant association was found between these measures of receptor function and MspI and DraI polymorphisms. Thus, both the genetic and the binding studies indicate that the alpha-2 adrenergic receptor may play a role in ADHD.

Adolescent↗
PubMed2006

The Antioxidants in Prevention of Cataracts Study: effects of antioxidant supplements on cataract progression in South India.

AIM: To determine if antioxidant supplements (beta carotene and vitamins C and E) can decrease the progression of cataract in rural South India. METHODS: The Antioxidants in Prevention of Cataracts (APC) Study was a 5 year, randomised, triple masked, placebo controlled, field based clinical trial to assess the ability of interventional antioxidant supplements to slow cataract progression. The primary outcome variable was change in nuclear opalescence over time. Secondary outcome variables were cortical and posterior subcapsular opacities and nuclear colour changes; best corrected visual acuity change; myopic shift; and failure of treatment. Annual examinations were performed for each subject by three examiners, in a masked fashion. Multivariate modelling using a general estimating equation was used for analysis of results, correcting for multiple measurements over time. RESULTS: Initial enrolment was 798 subjects. Treatment groups were comparable at baseline. There was high compliance with follow up and study medications. There was progression in cataracts. There was no significant difference between placebo and active treatment groups for either the primary or secondary outcome variables. CONCLUSION: Antioxidant supplementation with beta carotene, vitamins C and E did not affect cataract progression in a population with a high prevalence of cataract whose diet is generally deficient in antioxidants.

Adult↗
PubMed2006

Measles virus hemagglutinin protein expressed in transgenic lettuce induces neutralising antibodies in mice following mucosal vaccination.

Plant-made oral vaccines have the potential to overcome many of the limitations of traditional vaccines. Here we report on progress towards a lettuce-made measles vaccine. Lettuce is a palatable species which exhibits rapid growth in contained hydroponic systems and produces negligible quantities of toxins. Measles virus hemagglutinin (MV-H) protein was successfully expressed in transgenic lettuce and found to be immunogenic in mice. Lettuce extracts containing MV-H protein induced MV neutralising antibodies following intraperitoneal injection and intranasal inoculation of mice. Using a sequential prime-boost strategy in which mice were vaccinated with MV-H DNA followed by an orally delivered freeze-dried MV-H lettuce formulation a 10-fold increased in MV-specific IgG titers was observed relative to mice vaccinated with control lettuce formulations (p=0.05). MV-H protein was stable in freeze-dried lettuce for up to 13 months at room temperature, and survived at least a week at temperatures as high as 50 degrees C. This research represents a significant step towards the development of measles vaccine formulation that is effective, temperature-stable, easy to administer in a resource-poor setting and amenable to large scale manufacture.

Administration, Intranasal↗
PubMed2006

Human-mediated foot-and-mouth disease epidemic dispersal: disease and vector clusters.

Disease clusters were retrospectively explored at national level using a geo-referenced dataset from the 2001 Uruguayan Foot-and-Mouth Disease (FMD) epidemic. Disease location and time (first 11 epidemic weeks) were analysed across 250 counties (of which 160 were infected), without and with control for human mobility related factors (human population and road densities). The null hypothesis of random disease distribution over space and/or time was assessed with: (i) purely temporal; (ii) purely spatial; and (iii) space/time tests. At least within epidemic weeks 2 and 6, a principal disease cluster was observed in 33 contiguous counties (P < 0.01). Two secondary clusters, located at >100 km from each other, were also observed (P < 0.01). The purely spatial test that controlled for human population density identified two non-contiguous clusters (P < 0.01). Space and time analysis also revealed the same 33 counties as members of the principal cluster, of which 31 were also clustered when human population was controlled (P < 0.01). No clusters were reported by the spatial test when road density was assessed. The hypothesis that human mobility related factors autocorrelate with disease was empirically supported by two pieces of information: (i) removal of human population/road densities eliminated >93.9% of the counties included in the principal disease cluster; and (ii) statistically significant correlations (P < 0.05) were observed in the first three epidemic weeks between road density and the number of cases. Clusters where human population density was associated with 47% greater number of cases/sq. km than that of the principal cluster indicated possible roles as disease vectors (vector clusters). Selective control policy in vector clusters is recommended. Periodic (i.e. weekly) cluster and correlation analyses of both disease and other covariates may facilitate disease surveillance and help design space-specific control policy.

Animal Husbandry↗
PubMed2006

Enhanced monsoon precipitation and nitrogen deposition affect leaf traits and photosynthesis differently in spring and summer in the desert shrub Larrea tridentata.

Leaf-level CO2 assimilation (A(area)) can largely be predicted from stomatal conductance (g(s)), leaf morphology (SLA) and nitrogen (N) content (N(area)) in species across biomes and functional groups. The effects of simulated global change scenarios, increased summer monsoon rain (+H2O), N deposition (+N) and the combination (+H2O +N), were hypothesized to affect leaf trait-photosynthesis relationships differently in the short- and long-term for the desert shrub Larrea tridentata. During the spring, +H2O and +H2O +N plants had lower A(area) and g(s), but similar shoot water potential (Psi(shoot)) compared with control and +N plants; differences in A(area) were attributed to lower leaf N(area) and g(s). During the summer, +H2O and +H2O +N plants displayed higher A(area) than control and +N plants, which was attributed to higher Psi(shoot), g(s) and SLA. Throughout the year, A(area) was strongly correlated with g(s) but weakly correlated with leaf N(area) and SLA. We concluded that increased summer monsoon had a stronger effect on the performance of Larrea than increased N deposition. In the short term, the +H2O and +H2O +N treatments were associated with increasing A(area) in summer, but also with low leaf N(area) and lower A(area) in the long term the following spring.

Carbon Dioxide↗
PubMed2005

Enhanced basal apoptosis in cultured term human cytotrophoblasts is associated with a higher expression and physical interaction of p53 and Bak.

We tested the hypothesis that the expression levels of p53 and the pro-apoptotic mediators from the Bcl-2 family are higher in cytotrophoblasts, when compared to cultures with abundant syncytiotrophoblasts. Cytotrophoblasts isolated from normal term human placentas were cultured in Dulbecco's Modified Eagle medium (DMEM) for 24 h, when the cytotrophoblast phenotype predominates, in DMEM for 72 h, when the syncytiotrophoblast phenotype predominates, or in Ham's-Waymouth medium or DMEM with 1.5% dimethylsulfoxide, each of which maintains the cytotrophoblast phenotype through 72 h of culture. Apoptosis was assessed by detection of cleavage products of poly-ADP-ribose polymerase, by expression of cleaved cytokeratin 18 intermediate filaments, and by assessment of caspase-3 activity. Independent of time in culture, cytotrophoblasts showed higher levels of apoptosis compared to syncytiotrophoblasts. Cytotrophoblasts also expressed a 2-fold higher level of p53, a 2-fold lower level of 60 kDa Mdm-2 protein, a 2-fold higher level of Bak, but no differences in the expression of 90 kDa Mdm-2, Bcl-2, Bcl-X(L), Mcl-1, Bax, Bad, and Bad phosphorylated at the serine(112), serine(136), or serine(155) sites, compared to the syncytiotrophoblasts. Using co-immunoprecipitation, we demonstrated a greater degree of Bak-p53 interaction in cytotrophoblasts than in syncytiotrophoblasts. We also detected Bak-Mcl-1 interaction that was no different between the two phenotypes. Among the proteins studied, enhanced p53 activity, differential Bak expression, and Bak-p53 interactions may contribute to the higher level of constitutive apoptosis in cultures of cytotrophoblasts compared to syncytiotrophoblasts.

Apoptosis↗
PubMed2005

Crude saponins improve the immune response to an oral plant-made measles vaccine.

Millions of people live in areas where infectious diseases, such as measles, are endemic and resources are scarce. Heat-stable vaccines that are delivered orally will greatly enhance vaccination programs in these areas. A stumbling block in the development of oral vaccines is the availability of safe and effective mucosal adjuvants, especially for use with subunit vaccines. The experiments presented here examine the ability of CTB/CT, LT(R192G) and crude Quillaja saponin extracts to stimulate MV-specific immune responses in mice, following oral immunisation with plant-made measles virus hemagglutinin (MV-H) protein. LT(R192G) and crude saponin extracts both functioned as potent mucosal adjuvants when ad-mixed with plant-made MV-H protein, and were more effective than CTB/CT. MV-H protein supplemented with saponin extract induced the strongest MV-specific responses, in the greatest number of mice. Crude saponins are routinely used by the food and beverage industry at concentrations greater than those required for adjuvanticity, and as such, they have a better safety profile than bacterial enterotoxins. This study demonstrates their potential as adjuvants for use with oral plant-made vaccines.

Adjuvants, Immunologic↗
PubMed2005

PLAC1 expression increases during trophoblast differentiation: evidence for regulatory interactions with the fibroblast growth factor-7 (FGF-7) axis.

PLAC1 is a recently described, trophoblast-specific gene that localizes to a region of the X-chromosome important in placental development. Immunohistochemical analysis demonstrated that PLAC1 polypeptide localizes to the differentiated syncytiotrophoblast throughout gestation (8-41 weeks) as well as a small population of villous cytotrophoblasts. Consistent with these observations, quantitative RT-PCR demonstrated that PLAC1 mRNA increases more than 300-fold during cytotrophoblast differentiation in culture to form syncytiotrophoblasts. Agents known to be relevant to trophoblast differentiation were then tested for the ability to influence PLAC1 expression. Fibroblast growth factor-7 (FGF-7), also known as keratinocyte growth factor (KGF), stimulated PLAC1 mRNA expression approximately two-fold in the BeWo(b30) trophoblast cell line. FGF-7 stimulation was significantly inhibited by PD-98059 and wortmannin suggesting mediation via MAP kinase and PI-3 kinase-dependent signaling pathways. Interestingly, epidermal growth factor (EGF) treatment of trophoblasts had no effect on PLAC1 expression alone, but potentiated the effect of FGF-7, suggesting the presence of a regulatory interaction of the two growth factors. FGF-7 and its receptor, FGFR-2b, exhibited spatial overlap with PLAC1 suggesting these regulatory interactions are physiologically relevant during gestation. These data demonstrate PLAC1 expression is upregulated during trophoblast differentiation, localizing primarily to the differentiated syncytiotrophoblast. Furthermore PLAC1 expression is specifically regulated by peptide growth factors relevant to trophoblast differentiation.

Cell Differentiation↗
PubMed2005

Fibrin enhances differentiation, but not apoptosis, and limits hypoxic injury of cultured term human trophoblasts.

We hypothesized that fibrin enhances apoptosis and modulates differentiation of trophoblast in vitro. Cytotrophoblasts isolated from normal term human placentas were cultured < or =72 h in DMEM-10%-FBS on a fibrin matrix in standard or hypoxic conditions. Trophoblasts were cultured on plastic (control), type I collagen (matrix control), or dishes with fibrinogen, fibrin degradation products (FDP), thrombin, plasma fibronectin or cellular fibronectin. Apoptosis was determined by western analysis of the cleavage products of poly-ADP-ribose polymerase and cytokeratin 18 and caspase 3 activity. Cell cycle regulation was quantified by expression of proliferating cell nuclear antigen (PCNA) and p27 protein. Differentiation was determined by media level of hCG and hPL. Compared to the two controls, fibrin matrix had no effect on trophoblast apoptosis or total cell death in standard conditions. Neither fibrin nor collagen altered expression of PCNA or p27. In contrast, fibrin significantly increased the secretion of both hCG and hPL. Fibrin, but not FDP, thrombin or fibronectins, promoted hormonal differentiation. Fibrin limited the impact of a < or =8h of hypoxia on trophoblast hormone release but did not avert the effects of 24h of low oxygen and did not alter apoptosis in hypoxic trophoblast. We conclude that fibrin provides an environment conducive for trophoblast re-epithelialization of the surface of villi, where injury is marked by fibrin deposition.

Apoptosis↗
PubMed2005

Bivariate linkage scan for reading disability and attention-deficit/hyperactivity disorder localizes pleiotropic loci.

BACKGROUND: There is a growing interest in the study of the genetic origins of comorbidity, a direct consequence of the recent findings of genetic loci that are seemingly linked to more than one disorder. There are several potential causes for these shared regions of linkage, but one possibility is that these loci may harbor genes with manifold effects. The established genetic correlation between reading disability (RD) and attention-deficit/hyperactivity disorder (ADHD) suggests that their comorbidity is due at least in part to genes that have an impact on several phenotypes, a phenomenon known as pleiotropy. METHODS: We employ a bivariate linkage test for selected samples that could help identify these pleiotropic loci. This linkage method was employed to carry out the first bivariate genome-wide analysis for RD and ADHD, in a selected sample of 182 sibling pairs. RESULTS: We found evidence for a novel locus at chromosome 14q32 (multipoint LOD=2.5; singlepoint LOD=3.9) with a pleiotropic effect on RD and ADHD. Another locus at 13q32, which had been implicated in previous univariate scans of RD and ADHD, seems to have a pleiotropic effect on both disorders. 20q11 is also suggested as a pleiotropic locus. Other loci previously implicated in RD or ADHD did not exhibit bivariate linkage. CONCLUSIONS: Some loci are suggested as having pleiotropic effects on RD and ADHD, while others might have unique effects. These results highlight the utility of this bivariate linkage method to study pleiotropy.

Adolescent↗
PubMed2004

The self-perceived role and educational needs of pharmaceutical representatives: a survey.

INTRODUCTION: Despite considerable debate in the medical literature about the educational utility of pharmaceutical representatives (PR), little is known about their attitudes towards their role as marketers and/or educators, their ability to provide comprehensive information about products and their learning needs. DESIGN: A survey. SUBJECTS AND METHOD: Questionnaires were mailed to 606 PRs from five Canadian pharmaceutical companies. RESULTS: Of 309 (51%) respondents, 98% strongly agreed or agreed they had a role in educating doctors, while 52% strongly disagreed or disagreed their main goal was marketing. Overall, 92% agreed they had received adequate training to perform a well-informed detail, and 96% reported the information they provide is accurate. The majority (66%) felt a university-accredited program would improve the quality of their detailing. CONCLUSION: Most PRs believe their main goal is education. Despite most reporting that they had received adequate training, they felt that a university-accredited educational program would improve the quality of detailing. The number of years that a PR spent in the industry appears to have an effect on how they perceive their role.

Canada↗
PubMed2002

Hypoxia reduces expression and function of system A amino acid transporters in cultured term human trophoblasts.

We tested the hypothesis that hypoxia diminishes the expression and transport of neutral amino acids by system A in full-term human trophoblasts. Cytotrophoblasts from normal human placentas were cultured in standard conditions of 20% O(2) or in 1% and 3% O(2) for 24 h before assay. Neutral amino acid transport for systems A, ASC, and L was assayed at 24 and 72 h by the cluster-tray technique. Hypoxia during the initial 24 h of culture reduced system A transport by 82% in 1% O(2) and by 37% in 3% O(2) (P < 0.01) compared with standard conditions. Hypoxia during the latter 24 h of the 72 h in culture reduced system A transport by 55% in 1% O(2) and by 20% in 3% O(2) (P < 0.05) compared with standard conditions at 72 h. Hypoxia (1% O(2)) also reduced total amino acid transport by 40% in the more differentiated syncytiotrophoblasts present at 72 h. Northern analysis of trophoblasts in standard conditions showed that subtypes of human amino acid transporter A (hATA1 and hATA2) were each expressed in cytotrophoblasts and syncytiotrophoblasts. Hypoxia decreased expression of hATA1 and hATA2 in both trophoblast phenotypes. We conclude that hypoxia downregulates system A transporter expression and activity in cultured human trophoblasts.

Amino Acid Transport System A↗
PubMed2002

Evidence for linkage and association with reading disability on 6p21.3-22.

Reading disability (RD), or dyslexia, is a common heterogeneous syndrome with a large genetic component. Several studies have consistently found evidence for a quantitative-trait locus (QTL) within the 17 Mb (14.9 cM) that span D6S109 and D6S291 on chromosome 6p21.3-22. To characterize further linkage to the QTL, to define more accurately the location and the effect size, and to identify a peak of association, we performed Haseman-Elston and DeFries-Fulker linkage analyses, as well as transmission/disequilibrium, total-association, and variance-components analyses, on 11 quantitative reading and language phenotypes. One hundred four families with RD were genotyped with a new panel of 29 markers that spans 9 Mb of this region. Linkage results varied widely in degree of statistical significance for the different linkage tests, but multipoint analysis suggested a peak near D6S461. The average 6p QTL heritability for the 11 reading and language phenotypes was 0.27, with a maximum of 0.66 for orthographic choice. Consistent with the region of linkage described by these studies and others, there was a peak of transmission disequilibrium with a QTL centered at JA04 (chi2=9.48; empirical P=.0033; orthographic choice), and there was strong evidence for total association at this same marker (chi2=11.49; P=.0007; orthographic choice). Although the boundaries of the peak could not be precisely defined, the most likely location of the QTL is within a 4-Mb region surrounding JA04.

Adolescent↗
PubMed2001

Urine detection of survivin and diagnosis of bladder cancer.

CONTEXT: Dysregulation of apoptosis may favor onset and progression of cancer and influence response to therapy. Survivin is an inhibitor of apoptosis that is selectively overexpressed in common human cancers, but not in normal tissues, and that correlates with aggressive disease and unfavorable outcomes. OBJECTIVE: To investigate the potential suitability of survivin detection in urine as a novel predictive/prognostic molecular marker of bladder cancer. DESIGN, SETTING, AND PATIENTS: Survey of urine specimens from 5 groups: healthy volunteers (n = 17) and patients with nonneoplastic urinary tract disease (n = 30), genitourinary cancer (n = 30), new-onset or recurrent bladder cancer (n = 46), or treated bladder cancer (n = 35), recruited from 2 New England urology clinics. MAIN OUTCOME MEASURES: Detectable survivin levels, analyzed by a novel detection system and confirmed by Western blot and reverse transcriptase polymerase chain reaction (RT-PCR), in urine samples of the 5 participant groups. RESULTS: Survivin was detected in the urine samples of all 46 patients with new or recurrent bladder cancer using a novel detection system (31 of 31) and RT-PCR (15 of 15) methods. Survivin was not detected in the urine samples of 32 of 35 patients treated for bladder cancer and having negative cystoscopy results. None of the healthy volunteers or patients with prostate, kidney, vaginal, or cervical cancer had detectable survivin in urine samples. Of the 30 patients with nonneoplastic urinary tract disease, survivin was detected in 3 patients who had bladder abnormalities noted using cystoscopy and in 1 patient with an increased prostate-specific antigen level. Patients with low-grade bladder cancer had significantly lower urine survivin levels than patients with carcinoma in situ (P =.002). CONCLUSIONS: Highly sensitive and specific determination of urine survivin appears to provide a simple, noninvasive diagnostic test to identify patients with new or recurrent bladder cancer.

Adult↗
PubMed2001

The effects of dredge-spoil dumping on a shallow water soft-sediment community in the Solitary Islands Marine Park, NSW, Australia.

In December 1999, 28,000 m3 of sediment was dredged from two sites within the harbour at Coffs Harbour, NSW. Dredging was carried out using a trailing suction hopper-dredge which transported the spoil to a shallow (6 m) site within the adjacent Solitary Islands Marine Park for disposal. Evaluation of the effects of the dredge-spoil dumping at the receiving site was conducted by taking replicated van Veen grab samples at the disposal site and at two control sites, before, immediately after, and three months after dumping. The results indicated that dredge-spoil dumping had no detectable effect on either the structure of the invertebrate community or the physical characteristics of sediment at the receiving site. Although there were some significant faunistic differences between samples from the disposal site and the control sites immediately following dumping, these were related to pre-existing differences between sites rather than to the effects of dredge-spoil disposal. Four principal factors are likely to have contributed to the lack of impact: (i) dredged material had similar sedimentary characteristics to those at the receiving site; (ii) dredged material was free from contaminants; (iii) the disposal method systematically distributed a number of shallow layers of sediment over the disposal site and thus motile macrofauna had the opportunity to migrate upwards between passes of the barge; and (iv) the disposal site was in a high energy environment where the resident biota are likely to be adapted to dynamic sedimentary conditions. The lack of detectable effects suggests that the disposal strategy was one which minimized impacts within an area which has high conservation value and should thus be adopted as a model for future works within the region.

Adaptation, Physiological↗
PubMed2001

Prospective results of a standardized algorithm based on hemodynamic status for managing pediatric solid organ injury.

BACKGROUND: Controversy surrounds the need for ICU admission, prolonged bed rest, and the duration of activity restrictions for children sustaining blunt trauma. Adult literature supports management based on hemodynamic status, not CT grade. STUDY DESIGN: A 3-year prospective study of a standardized management algorithm for hemodynamically normal pediatric patients with blunt liver or spleen injury was performed. Patient selection was based on vital signs, irrespective of injury grade on CT. Patients requiring ICU admission for nonliver or nonspleen injury were excluded. Patients were admitted to a surgical ward with serial hematocrit levels. Discharge occurred 48 hours postinjury if patients had no abdominal tenderness, tolerated a regular diet, and had a stable hematocrit. Patients were allowed noncontact activity, including school, after discharge. Patients were followed up at 1 month with ultrasonographic imaging. RESULTS: Eighty-nine patients sustained blunt liver or spleen injury. Forty-five patients were excluded for other injuries (Glasgow Coma Scale < 13, 32 of 45); the remaining 44 patients had a mean age of 8.9 years (range 2 to 17 years), Injury Severity Score 10.6 (range 4 to 33), liver grade 2.1, and splenic injury grade 2.3. Mechanisms of injury were predominately motor vehicle collisions (59%). All patients were managed nonoperatively without transfusion; 43 of 44 patients completed the algorithm. Mean observation was 55.2 +/- 12.3 hours. One-month followup occurred in 33 of 44 patients, with one complication detected and no delayed bleeding. CONCLUSION: Management of pediatric solid organ injury should be guided by hemodynamic status and not injury grade on CT. Hemodynamically normal children can be safely managed without intensive care monitoring, do not need prolonged hospitalization, and can resume school on discharge.

Adolescent↗
PubMed2001

Etiology of reading difficulties and rapid naming: the Colorado Twin Study of Reading Disability.

Children with reading deficits perform more slowly than normally-achieving readers on speed of processing measures, such as rapid naming (RN). Although rapid naming is a well-established correlate of reading performance and both are heritable, few studies have attempted to assess the cause of their covariation. Measures of rapid naming (numbers, colors, objects, and letters subtests), phonological decoding, orthographic choice, and a composite variable (DISCR) derived from the reading recognition, reading comprehension, and spelling subtests of the Peabody Individual Achievement Test were obtained from a total of 550 twin pairs with a positive school history of reading problems. Basic DeFries and Fulker (DF) multiple regression models for the analysis of selected twin data confirmed the heritable nature of phonological decoding, orthographic choice, DISCR, and rapid-naming composites. Bivariate DF models were employed to examine the extent to which deficits in the three reading-related measures covary genetically with rapid naming. Significant bivariate heritability estimates for each of the reading measures with the numbers and letters rapid-naming composite were also obtained. As expected, univariate sib-pair linkage analyses indicated the presence of a quantitative trait locus (QTL) on chromosome 6p21.3 for phonological decoding and orthographic choice deficits. Bivariate linkage analyses were then conducted to test the hypothesis that this QTL for reading difficulties is pleiotropic for slower performance on RN tasks. The results obtained from these analyses did not provide substantial evidence that the 6p QTL for reading difficulties has significant effects on rapid naming; however, larger samples would be required to test this hypothesis more rigorously.

Adolescent↗