Benefits of literacy interventionsto early readers with specific language weaknesses.

It has been estimated that children who learn and are exposed to two languages prior to puberty will become the majority worldwide (Tucker, 1998). Communities evolving into highly linguistically-diverse environments have the potential to pose a considerable challenge not only among individuals, but also to educational institutions, as immersion in languages learned does not guarantee linguistic proficiency. Hence, more ethnically-disparate countries, such as the Philippines and New Zealand, will need to develop responsive educational programs that accommodate successful bilingualism and support a range of learners. For example, children presenting with language learning deficits can be placed at a greater disadvantage in educational contexts, especially when this hinders proficiency in the language of education and leads to difficulties in literacy acquisition. Studies reported in this thesis focused on methods that might be valuable to reduce difficulties experienced by such populations of early learners. The thesis studies assessed two treatment approaches: one focused on phonological awareness and a second targeted morphological skills. Both approaches were assessed to determine their efficacy in facilitating the growth of language and reading skills among children with specific language weaknesses in their first formal year of primary school. Improvements in language processing (phonological, morphological and vocabulary), word identification, and sentence comprehension in two country contexts (New Zealand and the Philippines) were the focus of the research. In the first study, the focus was on children from monolingual versus bilingual backgrounds in New Zealand who showed evidence of weaknesses in the English language. Twenty year 1 pupils (mean age = 5.8) were selected from a group of students identified by their classroom teachers as language weak. In the second study, the sample comprised 16 typically-developing bilingual and 15 English language weak bilingual children from the Philippines (mean age = 6.3) who were all Filipino speakers but were using English as the language of education in school. In both studies, participants were screened using standardized language assessments and measures of non-verbal intelligence, basic reading skills (comprehending words and sentences), language skills (including vocabulary), phonological and morphological awareness levels. All children showed no evidence of sensory, behavioural or neurological problems and their non-verbal intelligence score was within 85 to 115 points on the Primary Test of Non-verbal Intelligence. Students with language weaknesses were those who showed poor scores in several areas of verbal language processing. The design evaluated the performance of the children at three different time points: once prior to the introduction of the interventions, once after the first intervention was given and once after the second intervention was completed. In both country contexts, roughly half of each group completed the phonological intervention first whereas the rest completed the morphological intervention first. Results indicated that specific gains in phonological processing were observed for the phonological-based intervention across groups in both countries (New Zealand and the Philippines). However, for the New Zealand context, gains for both monolingual and bilingual language weak children were generally more evident with the phonological intervention, whereas in the Philippines, the morphological intervention showed specific gains in morphology and word meaning tasks. When students had completed both interventions, there was evidence for all groups to show gains across the range of measures used in the study. The findings suggest that providing an integrated phonological and morphological awareness intervention among school-aged children may be an effective approach to support the language and reading development of students experiencing difficulties with the acquisition of English language skills. Such positive effects may be evident whether children are from a predominantly monolingual or bilingual/second language background

Metal ion-dependent biological properties of a chelator-derivatised somatostatin analogue for tumour targeting

A publicar na Revista Chemistry a European JournalSomatostatin-based radioligands were shown to have sensitive imaging properties for neuroendocrine tumours and their metastases. The potential of [55Co]DOTATOC (DOTATOC = 4,7, 10-tricarboxymethyl-1,4,7,10- tetraazacyclododecane-1-yl-acetyl-DPhe- Lys-Tyr-D-Trp-Lys-Thr-Lys-1- threoninol (disulfide bond) as a new radiopharmaceutical agent for PET was evaluated. 57Co was used as a surrogate of the positron emitter 55Co and the pharmacokinetics of [57Co]DOTATOC was investigated using two nude mouse models. The somatostatin receptor subtype (sst1-5) affinity profile of [natCo]DOTA-TOC was assessed using autoradiographic methods on membranes transfected with human somatostatin receptor subtypes. These studies revealed that [57Co]DOTATOC is an sst2-specific radiopeptide presenting the highest affinity ever found for the sst2 receptor subtype. The rate of internalisation into the AR4-2J cell line also was the highest found for any somatostatin-based radiopeptide. Biodistribution studies, performed in nude mice bearing the AR4-2J tumour or a transfected HEK-sst2 cell-based tumour, showed high and specific uptake in the tumour and in other sst receptor-expressing tissues reflecting the high receptor binding affinity and the high rate of internalisation. The pharmacologic differences between [57Co]DOTATOC and [67Ga]DOTATOC were discussed in terms of the structural parameters found for the chelate models CoII(DOTA)2- and GaIII(DOTA)-, whose X-ray structures were determined. Both chelates show sixfold coordination in pseudooctahedral arrangements

Tricarbonyl M(I) (M = Re, 99mTc) complexes bearing acridine fluorophores : synthesis, characterization, DNA interaction studies and nuclear targeting

© The Royal Society of Chemistry 2010New pyrazolyl-diamine ligands with acridine derivatives at the 4-position of the pyrazolyl ring were synthesized and characterized (L1 and L2). Coordination towards the fac-[M(CO)3]+ (M = Re, 99mTc) led to complexes fac-[M(CO)3(κ3-L)] (L = L1: M = Re1, Tc1; L = L2: M = Re2, Tc2). The interaction of the novel pyrazolyl-diamine ligands (L1 and L2) and rhenium(I) complexes (Re1 and Re2) with calf thymus DNA (CT-DNA) was investigated by a variety of techniques, namely UV-visible , fluorescence spectroscopy and circular and linear dichroism . Compounds L1 and Re1 have moderate affinity to CT-DNA and bind to DNA by intercalation, while L2 and Re2 have a poor affinity for CT-DNA. Moreover, LD measurements showed that L1 and Re1 act as perfect intercalators . By confocal fluorescence microscopy we found that L1 and Re1 internalize and localize in the nucleus of B16F1 murine melanoma cells . The congener Tc1 complex also targets the cell nucleus exhibiting a time-dependent cellular uptake and a fast and high nuclear internalization (67.2% of activity after 30 min). Plasmid DNA studies have shown that Tc1 converts supercoiled (sc) puc19 DNA to the open circular (oc) form.Teresa Esteves and Sofia Gama thank the FCT for a doctoral and postdoctoral research grants (SFRH/BD/29154/2006 and SFRH/BPD/29564/2006, respectively). COST Action D39 is also acknowledge. The QITMS instrument was acquired with the support of the Programa Nacional de Reequipamento Científico (Contract>REDE/1503/REM/2005-ITN) of Fundação para a Ciência e a Tecnologia and is part of RNEM - Rede Nacional de Espectrometria de Massa

Are radiogallium-labelled DOTA-conjugated somatostatin analogues superior to those labelled with other radiometals?

Purpose: Gallium-68 is a metallic positron emitter with a half-life of 68min that is ideal for the in vivo use of small molecules, such as [68Ga-DOTA,Tyr3]octreotide, in the diagnostic imaging of somatostatin receptor-positive tumours. In preclinical studies it has shown a striking superiority over its 111In-labelled congener. The purpose of this study was to evaluate whether third-generation somatostatin-based, radiogallium-labelled peptides show the same superiority. Methods: Peptides were synthesised on solid phase. The receptor affinity was determined by in vitro receptor autoradiography. The internalisation rate was studied in AR4-2J and hsst-HEK-transfected cell lines. The pharmacokinetics was studied in a rat xenograft tumour model, AR4-2J. Results: All peptides showed high affinities on hsst2, with the highest affinity for the GaIII-complexed peptides. On hsst3 the situation was reversed, with a trend towards lower affinity of the GaIII peptides. A significantly increased internalisation rate was found in sst2-expressing cells for all 67Ga-labelled peptides. Internalisation into HEK-sst3 was usually faster for the 111In-labelled peptides. No internalisation was found into sst5. Biodistribution studies employing [67Ga-DOTA,1-Nal3]octreotide in comparison to [111In-DOTA,1-Nal3]octreotide and [67Ga-DOTA,Tyr3]octreotide showed a significantly higher and receptor-mediated uptake of the two 67Ga-labelled peptides in the tumour and somatostatin receptor-positive tissues. A patient study illustrated the potential advantage of a broad receptor subtype profile radiopeptide over a high-affinity sst2-selective radiopeptide. Conclusion: This study demonstrates that 67/68Ga-DOTA-octapeptides show distinctly better preclinical, pharmacological performances than the 111In-labelled peptides, especially on sst2-expressing cells and the corresponding animal models. They may be excellent candidates for further development for clinical studie

DOTA-NOC, a high-affinity ligand of somatostatin receptor subtypes 2, 3 and 5 for labelling with various radiometals

Earlier studies have shown that modification of the octapeptide octreotide in positions 3 and 8 may result in compounds with increased somatostatin receptor affinity that, if radiolabelled, display improved uptake in somatostatin receptor-positive tumours. The aim of a recent research study in our laboratory was to employ the parallel peptide synthesis approach by further exchanging the amino acid in position 3 of octreotide and coupling the macrocyclic chelator DOTA(1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) to these peptides for labelling with radiometals like gallium-67 or -68, indium-111, yttrium-90 and lutetium-177. The purpose was to find radiopeptides with an improved somatostatin receptor binding profile in order to extend the spectrum of targeted tumours. A first peptide, [111In,90Y-DOTA]-1-Nal3-octreotide (111In,90Y-DOTA-NOC), was isolated which showed an improved profile. InIII-DOTA-NOC exhibited the following IC50 values (nM) when studied in competition with [125I][Leu8, d-Trp22, Tyr25]somatostatin-28 (values for YIII-DOTA-NOC are shown in parentheses): sstr2, 2.9±0.1 (3.3±0.2); sstr3, 8±2 (26±1.9); sstr5, 11.2±3.5 (10.4±1.6). Affinity towards sstr1 and 4 was very low or absent. InIII-DOTA-NOC is superior to all somatostatin-based radiopeptides having this particular type of binding profile, including DOTA-lanreotide, and has three to four times higher binding affinity to sstr2 than InIII,YIII-DOTA-Tyr3-octreotide (InIII,YIII-DOTA-TOC). In addition, [111In]DOTA-NOC showed a specific and high rate of internalization into AR4-2J rat pancreatic tumour cells which, after 4h, was about two times higher than that of [111In]DOTA-TOC and three times higher than that of [111In]DOTA-octreotide ([111In]DOTA-OC). The internalized radiopeptides were externalized intact upon 2h of internalization followed by an acid wash. After 2-3h of externalization a plateau is reached, indicating a steady-state situation explained by reactivation of the receptors followed by re-endocytosis. Biodistribution studies in CA 20948 tumour-bearing rats showed rapid clearance from all sstr-negative tissues except the kidneys. At 4h the uptake of [111In]DOTA-NOC in the tumour and sstr-positive tissues, such as adrenals, stomach and pancreas, was three to four times higher than that of [111In]DOTA-TOC. Differential blocking studies indicate that this is at least partially due to the uptake mediated by sstr3 and sstr5. These very promising preclinical data justify the use of this new radiopeptide for imaging and potentially internal radiotherapy studies in patient

Biokinetics and dosimetry of 111In-DOTA-NOC-ATE compared with 111In-DTPA-octreotide

Purpose: The biokinetics and dosimetry of 111In-DOTA-NOC-ATE (NOCATE), a high-affinity ligand of SSTR-2 and SSTR-5, and 111In-DTPA-octreotide (Octreoscan™, OCTREO) were compared in the same patients. Methods: Seventeen patients (10 men, 7 women; mean age 60years), referred for an OCTREO scan for imaging of a neuroendocrine tumour (15), thymoma (1) or medullary thyroid carcinoma (1), agreed to undergo a second study with NOCATE. Whole-body anterior-posterior scans were recorded 0.5 (100% reference scan), 4, 24 and 48h (17 patients) and 120h (5 patients) after injection. In 16 patients the OCTREO scan (178 ± 15MBq) was performed 16 ± 5days before the NOCATE scan (108 ± 14MBq) with identical timing; 1 patient had the NOCATE scan before the OCTREO scan. Blood samples were obtained from 14 patients 5min to 48h after injection. Activities expressed as percent of the initial (reference) activity in the whole body, lung, kidney, liver, spleen and blood were fitted to biexponential or single exponential functions. Dosimetry was performed using OLINDA/EXM. Results: Initial whole-body, lung and kidney activities were similar, but retention of NOCATE was higher than that of OCTREO. Liver and spleen uptakes of NOCATE were higher from the start (p < 0.001) and remained so over time. Whole-body activity showed similar α and β half-lives, but the β fraction of NOCATE was double that of OCTREO. Blood T 1/2β for NOCATE was longer (19 vs. 6h). As a result, the effective dose of NOCATE (105μSv/MBq) exceeded that of OCTREO (52μSv/MBq), and the latter result was similar to the ICRP 106 value of 54μSv/MBq. Differential activity measurement in blood cells and plasma showed an average of <5% of NOCATE and OCTREO attached to globular blood components. Conclusion: NOCATE showed a slower clearance from normal tissues and its effective dose was roughly double that of OCTRE

Biokinetics and dosimetry of (111)In-DOTA-NOC-ATE compared with (111)In-DTPA-octreotide.

PURPOSE: The biokinetics and dosimetry of (111)In-DOTA-NOC-ATE (NOCATE), a high-affinity ligand of SSTR-2 and SSTR-5, and (111)In-DTPA-octreotide (Octreoscan?, OCTREO) were compared in the same patients. METHODS: Seventeen patients (10 men, 7 women; mean age 60 years), referred for an OCTREO scan for imaging of a neuroendocrine tumour (15), thymoma (1) or medullary thyroid carcinoma (1), agreed to undergo a second study with NOCATE. Whole-body anterior-posterior scans were recorded 0.5 (100 % reference scan), 4, 24 and 48 h (17 patients) and 120 h (5 patients) after injection. In 16 patients the OCTREO scan (178 ± 15 MBq) was performed 16 ± 5 days before the NOCATE scan (108 ± 14 MBq) with identical timing; 1 patient had the NOCATE scan before the OCTREO scan. Blood samples were obtained from 14 patients 5 min to 48 h after injection. Activities expressed as percent of the initial (reference) activity in the whole body, lung, kidney, liver, spleen and blood were fitted to biexponential or single exponential functions. Dosimetry was performed using OLINDA/EXM. RESULTS: Initial whole-body, lung and kidney activities were similar, but retention of NOCATE was higher than that of OCTREO. Liver and spleen uptakes of NOCATE were higher from the start (p &lt; 0.001) and remained so over time. Whole-body activity showed similar α and β half-lives, but the β fraction of NOCATE was double that of OCTREO. Blood T (1/2)β for NOCATE was longer (19 vs. 6 h). As a result, the effective dose of NOCATE (105 μSv/MBq) exceeded that of OCTREO (52 μSv/MBq), and the latter result was similar to the ICRP 106 value of 54 μSv/MBq. Differential activity measurement in blood cells and plasma showed an average of &lt;5 % of NOCATE and OCTREO attached to globular blood components. CONCLUSION: NOCATE showed a slower clearance from normal tissues and its effective dose was roughly double that of OCTREO

Combination of terbium-161 with somatostatin receptor antagonists—a potential paradigm shift for the treatment of neuroendocrine neoplasms

Purpose: The β¯-emitting terbium-161 also emits conversion and Auger electrons, which are believed to be effective in killing single cancer cells. Terbium-161 was applied with somatostatin receptor (SSTR) agonists that localize in the cytoplasm (DOTATOC) and cellular nucleus (DOTATOC-NLS) or with a SSTR antagonist that localizes at the cell membrane (DOTA-LM3). The aim was to identify the most favorable peptide/terbium-161 combination for the treatment of neuroendocrine neoplasms (NENs). Methods: The capability of the 161Tb- and 177Lu-labeled somatostatin (SST) analogues to reduce viability and survival of SSTR-positive AR42J tumor cells was investigated in vitro. The radiopeptides' tissue distribution profiles were assessed in tumor-bearing mice. The efficacy of terbium-161 compared to lutetium-177 was investigated in therapy studies in mice using DOTATOC or DOTA-LM3, respectively. Results: In vitro, [161Tb]Tb-DOTA-LM3 was 102-fold more potent than [177Lu]Lu-DOTA-LM3; however, 161Tb-labeled DOTATOC and DOTATOC-NLS were only 4- to fivefold more effective inhibiting tumor cell viability than their 177Lu-labeled counterparts. This result was confirmed in vivo and demonstrated that [161Tb]Tb-DOTA-LM3 was significantly more effective in delaying tumor growth than [177Lu]Lu-DOTA-LM3, thereby, prolonging survival of the mice. A therapeutic advantage of terbium-161 over lutetium-177 was also manifest when applied with DOTATOC. Since the nuclear localizing sequence (NLS) compromised the in vivo tissue distribution of DOTATOC-NLS, it was not used for therapy. Conclusion: The use of membrane-localizing DOTA-LM3 was beneficial and profited from the short-ranged electrons emitted by terbium-161. Based on these preclinical data, [161Tb]Tb-DOTA-LM3 may outperform the clinically employed [177Lu]Lu-DOTATOC for the treatment of patients with NENs