Synthesis of beta-D-arabinofuranosides: stereochemical differentiation between D- and L-enantiomers

The glycosylation of 3,5-O-di-tert-butylsilylene-protected d-thioarabinofuranosides with a range of glycosyl acceptors using NIS/AgOTf as promoters proceeded in a stereoselective manner to give the corresponding β-d-arabinofuranosides in high yields.     

Use of phenyl 2-alpha-selenoglycosides of N-acetylneuraminic acid as a glycosyl donor for the glycosylation reactions

Phenyl 2-alpha-selenoglycosides of Neu5Ac were successfully prepared from the corresponding peracetylated chloro derivative of Neu5Ac 1 and phenylselenol in the presence of N,N-di-isopropylethylamine in excellent yields. The reaction of with various alcohols was effectively catalyzed by NIS/TfOH or DMTST to produce a variety of glycosides in moderate yields. Selective activation of over phenyl 2-alpha-thioglycoside of Neu5Ac with AgOTf/K(2)CO(3) was also achieved.     

Biosecurity surveillance design: detecting non-indigenous vertebrate introductions using risk and power

Ecosystems can be severely damaged by the introduction, establishment and spread of non-indigenous species (NIS) including vertebrates, invertebrates and plants. Development and use of natural areas poses a biosecurity risk regarding the introduction of increase NIS invasion risks, so biosecurity systems including prevention and detection measures are required. Even with the most rigorous biosecurity efforts, there is potential for NIS to evade quarantine and go on to establish and spread. The cost of such an event can be great, both environmentally and financially (e.g. containment/ management or eradication). We have developed a surveillance design methodology, for an application where increased use of a natural area may result in NIS incursions, even with extensive biosecurity systems. The surveillance design methodology acknowledges heterogeneity of risk in the study area and stratifies the area to optimise surveillance deployment, achieving great efficiencies and improvement in statistical power of detection. Many of the risk decisions require lack data and so the system incorporates expert opinion with available data. The design covers the broad range of potential NIS that may be introduced by using exemplar species and a variety of surveillance system components (SSCs) (such as a combination of formal scientific surveys, trapping methods, and casual observation) distributed optimally over time and space. The mix of SSCs can be manipulated to take into account such factors as their relative financial costs and demands on expertise. The methodology has the flexibility to be applied to various groups of potential NIS (e.g. vertebrates, invertebrates and plants), and the design can evolve as data are collected (adaptive management). Overall, the surveillance design methodology allows for an efficient use of resources, providing sufficient power to detect incursions, resulting in reduced environmental and financial costs from NIS incursions.     

Sodium iodide symporter in physiology and diseases -- the current state of knowledge

The sodium iodide symporter, called also the NIS protein is responsible for iodine trapping to the cell what is significant for the thyroid function. Identified and described for the first time in 1996 NIS protein is the matter of interest of investigators concerning the thyroid physiology and pathology as well as others organs which concentrate the iodine. Existing studies on the sodium iodide symporter include among others: indicating NIS protein expression in the thyroid diseases and extrathyroidal tissues, studying of the NIS antygenicity in the autoimmune diseases of thyroid, finding the molecular aspects of the difference in the NIS protein activity. The sodium iodide symporter is a base of radioiodine therapy of, as for now, thyroid diseases only. Showing NIS protein expression in other cancerous tissues provide a new therapeutic strategy for a variety of human cancers. Additionally, latest explorations indicate at an innovative destination of the studies concerning the sodium iodide symporter that is the gene therapy with the use of gene NIS transfer.     

Synthesis of monodeoxy analogues of the trisaccharide alpha-D-Glcp-(1-->3)-alpha-D-Manp-(1-->2)-alpha-D-ManpOMe recognised by Calreticulin/Calnexin

Six (3,4,4′,6′,3″ or 6″)-monodeoxy analogues of the title trisaccharide (1-6) have been prepared utilising monodeoxy monosaccharide precursors. The reducing end deoxy derivatives were synthesised by N-iodosuccinimide/silver trifluoromethanesulfonate (NIS/AgOTf)-promoted couplings of a common disaccharide thioglycoside donor 10 to suitably protected monodeoxy acceptors 9 and 12, affording trisaccharides, which after deprotection yielded target structures 1 and 2. The non-reducing end deoxy derivatives could similarly be produced by halide-assisted glycosylations of a common disaccharide acceptor 17 with monodeoxy glycosyl bromide donors (obtained from thioglycosides 18 and 20) to yield, after removal of protecting groups, target trisaccharides 3 and 4. The analogues with the deoxy function in the middle mannose residue, were obtained through orthogonal halide-assisted coupling of tetrabenzyl-glucopyranosyl bromide to monodeoxy thioglycoside acceptors to give thioglycoside disaccharides, which subsequently were used as donors in NIS/AgOTf-promoted couplings to a common 2-hydroxy-mannose acceptor 15 to afford trisaccharides; deprotection yielded the final target compounds 5 and 6.     

In vivo imaging of retinoic acid receptor activity using a sodium/iodide symporter and luciferase dual imaging reporter gene

Retinoic acids are natural derivatives of vitamin A, and play important roles in modulating tumor cell growth by regulating differentiation, thus suggesting the potential use of these derivatives in cancer therapy and prevention. To visualize the intranuclear responses of functional retinoic acid receptors, we have developed a dual-imaging reporter gene system based on the use of sodium/iodide symporter (NIS) and luciferase in cancer cell lines. NIS and luciferase genes were linked with an internal ribosome entry site, and placed under the control of an artificial cis-acting retinoic acid responsive element (pRARE/NL). After retinoic acid treatment, I-125 uptake by pRARE/NL transfected cells was found to have increased by up to about five times that of nontreated cells. The bioluminescence intensity of pRARE/NL transfected cells showed dose-dependency. In vivo luciferase images showed higher intensity in retinoic acid treated SK-RARE/NL tumors, and scintigraphic images of SK-RARE/NL tumors showed increased Tc-99m uptake after retinoic acid treatment. The NIS/luciferase imaging reporter system was sufficiently sensitive to allow the visualization of intranuclear retinoic acid receptor activity. This cis-enhancer imaging reporter system may be useful in vitro and in vivo for the evaluation of retinoic acid responses in such areas as cellular differentiation and chemoprevention.     

Amino acid residues in transmembrane segment IX of the Na+/I- symporter play a role in its Na+ dependence and are critical for transport activity

The Na+/I- symporter (NIS) is a key plasma membrane glycoprotein that mediates Na+-dependent active I- transport in the thyroid, lactating breast, and other tissues. The OH group of the side chain at position 354 in transmembrane segment (TMS) IX of NIS has been demonstrated to be essential for NIS function, as revealed by the study of the congenital I- transport defect-causing T354P NIS mutation. TMS IX has the most beta-OH group-containing amino acids (Ser and Thr) of any TMS in NIS. We have thoroughly characterized the functional significance of all Ser and Thr in TMS IX in NIS, as well as of other residues in TMS IX that are highly conserved in other transporters of the SLC5A protein family. Here we show that five beta-OH group-containing residues (Thr-351, Ser-353, Thr-354, Ser-356, and Thr-357) and Asn-360, all of which putatively face the same side of the helix in TMS IX, plus Asp-369, located in the membrane/cytosol interface, play key roles in NIS function and seem to be involved in Na+ binding/translocation.     

Normalisation to blood activity is required for the accurate quantification of Na/I symporter ectopic expression by SPECT/CT in individual subjects

The utilisation of the Na/I symporter (NIS) and associated radiotracers as a reporter system for imaging gene expression is now reaching the clinical setting in cancer gene therapy applications. However, a formal assessment of the methodology in terms of normalisation of the data still remains to be performed, particularly in the context of the assessment of activities in individual subjects in longitudinal studies. In this context, we administered to mice a recombinant, replication-incompetent adenovirus encoding rat NIS, or a human colorectal carcinoma cell line (HT29) encoding mouse NIS. We used (99m)Tc pertechnetate as a radiotracer for SPECT/CT imaging to determine the pattern of ectopic NIS expression in longitudinal kinetic studies. Some animals of the cohort were culled and NIS expression was measured by quantitative RT-PCR and immunohistochemistry. The radioactive content of some liver biopsies was also measured ex vivo. Our results show that in longitudinal studies involving datasets taken from individual mice, the presentation of non-normalised data (activity expressed as %ID/g or %ID/cc) leads to 'noisy', and sometimes incoherent, results. This variability is due to the fact that the blood pertechnetate concentration can vary up to three-fold from day to day. Normalisation of these data with blood activities corrects for these inconsistencies. We advocate that, blood pertechnetate activity should be determined and used to normalise the activity measured in the organ/region of interest that expresses NIS ectopically. Considering that NIS imaging has already reached the clinical setting in the context of cancer gene therapy, this normalisation may be essential in order to obtain accurate and predictive information in future longitudinal clinical studies in biotherapy.     

Identification of in vivo phosphorylation sites and their functional significance in the sodium iodide symporter

The Na+/I- symporter (NIS)-mediated iodide uptake activity is the basis for targeted radioiodide ablation of thyroid cancers. Although it has been shown that NIS protein is phosphorylated, neither the in vivo phosphorylation sites nor their functional significance has been reported. In this study, Ser-43, Thr-49, Ser-227, Thr-577, and Ser-581 were identified as in vivo NIS phosphorylation sites by mass spectrometry. Kinetic analysis of NIS mutants of the corresponding phosphorylated amino acid residue indicated that the velocity of iodide transport of NIS is modulated by the phosphorylation status of Ser-43 and Ser-581. We also found that the phosphorylation status of Thr-577 may be important for NIS protein stability and that the phosphorylation status of Ser-227 is functionally silent. Thr-49 appears to be critical for proper local structure/conformation of NIS because mutation of Thr-49 to alanine, aspartic acid, or serine results in reduced NIS activity without alterations in total or cell surface NIS protein levels. Taken together, we showed that NIS protein levels and functional activity could be modulated by phosphorylation through distinct mechanisms.     

The synthesis of compatible solute analogues-solvent effects on selective glycosylation

Ethyl 6-O-acetyl-2,3,4-tribenzyl-1-d-thioglucoside and ethyl 6-O-acetyl-2,3,4-tribenzyl-1-d-thiogalactoside, as a mixture of anomers, were employed in the study of the influence of solvent in the stereoselectivity of the glycosylation reaction with small and reactive acceptors. High α-selectivities were obtained in the glycosylation reactions using NIS/TfOH as activator and ethyl ether as the solvent at −60 °C. Other solvent mixtures such as dichloromethane, THF, THF/ethyl ether and toluene/dioxane were not nearly as selective. The corresponding thiogalactoside underwent similar glycosylations with the same solvents but with low anomer selectivity. These glycosides are key intermediates for the synthesis of new analogues of compatible solutes.     

Evaluation of stochastic gravity model selection for use in estimating non-indigenous species dispersal and establishment

Predicting dispersal of nonindigenous species (NIS) is an essential component of risk analysis and management, as preventative measures are most readily applied at this stage of the invasion sequence. Gravity models provide one of the most useful techniques available to model dispersal of nonindigenous invasive species (NIS) across heterogeneous landscapes, as these models are able to capture transport patterns of recreational boaters who are dominant vectors responsible for aquatic NIS dispersal. Despite the widespread use of gravity models in forecasting biological invasions, different classes of gravity models have not been evaluated regarding their comparative ability to capture recreational transport patterns and subsequent use in predicting NIS establishment. Here we evaluate model selection between unconstrained, total-flow-constrained, production-constrained and doubly-constrained stochastic gravity models to assess dispersal of the spiny waterflea Bythotrephes between Ontario lakes. Differences between the models relate to the amount of data required and constraints under which calculations of source/destination interactions are made. For each class of gravity model, we then estimated the probability of a lake having established Bythotrephes populations by modeling the relationship between empirical presence/absence data and inbound recreational traffic (i.e. propagule pressure) via boosted regression. The unconstrained gravity model provided the best fit to observed traffic patterns of recreational boaters. However, when output from the gravity models was used to predict Bythotrephes establishment, the doubly-constrained gravity model provided the strongest relationship between inbound recreational traffic and observed Bythotrephes presence/absence, followed by the production-constrained model. Our results indicate production-constrained gravity models offer an acceptable balance between modeling recreational boater traffic and their utility to estimate establishment probabilities.     

Scale invariance of immune system response rates and times: perspectives on immune system architecture and implications for artificial immune systems

Most biological rates and times decrease systematically with increasing organism body size. We use an ordinary differential equation (ODE) model of West Nile Virus in birds to show that pathogen replication rates decline with host body size, but natural immune system (NIS) response rates do not change systematically with body size. The scale-invariant detection and response of the NIS is surprising since the NIS has to search for small quantities of pathogens through larger physical spaces in larger organisms, and also respond by producing larger absolute quantities of antibody in larger organisms. We hypothesize that the NIS has evolved an architecture to efficiently neutralize pathogens. We investigate three different hypothesized NIS architectures using an Agent Based Model (ABM). We find that a sub-modular NIS architecture, in which lymph node number and size both increase sublinearly with body size, efficiently balances the tradeoff between local pathogen detection and global response. This leads to nearly scale-invariant detection and response consistent with experimental data. Similar to the NIS, physical space and resources are also important constraints on distributed systems, for example low-powered robots connected by short-range wireless communication. We show that the sub-modular design principles of the NIS can be applied to problems such as distributed robot control to efficiently balance the tradeoff between local search for a solution and global response or proliferation of the solution. We demonstrate that the lymphatic network of the NIS efficiently balances local and global communication, and we suggest a new approach for Artificial Immune Systems (AIS) that uses a sub-modular architecture to facilitate distributed search.     

Hydrocortisone and purinergic signaling stimulate sodium/iodide symporter (NIS)-mediated iodide transport in breast cancer cells

The sodium/iodide symporter (NIS) mediates a remarkably effective targeted radioiodide therapy in thyroid cancer; this approach is an emerging candidate for treating other cancers that express NIS, whether endogenously or by exogenous gene transfer. Thus far, the only extrathyroidal malignancy known to express functional NIS endogenously is breast cancer. Therapeutic efficacy in thyroid cancer requires that radioiodide uptake be maximized in tumor cells by manipulating well-known regulatory factors of NIS expression in thyroid cells, such as TSH, which stimulates NIS expression via cAMP. Similarly, therapeutic efficacy in breast cancer will likely depend on manipulating NIS regulation in mammary cells, which differs from that in the thyroid. Human breast adenocarcinoma MCF-7 cells modestly express endogenous NIS when treated with all-trans-retinoic acid (tRa). We report here that hydrocortisone and ATP each markedly stimulates tRa-induced NIS protein expression and plasma membrane targeting in MCF-7 cells, leading to at least a 100% increase in iodide uptake. Surprisingly, the adenyl cyclase activator forskolin, which promotes NIS expression in thyroid cells, markedly decreases tRa-induced NIS protein expression in MCF-7 cells. Isobutylmethylxanthine increases tRa-induced NIS expression in MCF-7 cells, probably through a purinergic signaling system independent of isobutylmethylxanthine's action as a phosphodiesterase inhibitor. We also observed that neither iodide, which at high concentrations down-regulates NIS in the thyroid, nor cAMP has a significant effect on NIS expression in MCF-7 cells. Our findings may open new strategies for breast-selective pharmacological modulation of functional NIS expression, thus improving the feasibility of using radioiodide to effectively treat breast cancer.     

Radioiodide uptake and sodium iodide symporter expression in breast carcinoma

Breast cancer is a common malignancy in women all over the world and novel therapeutic approaches are required for the treatment of patients who become refractory to conventional therapies. Thyroid cancer is being treated successfully with radioiodine since many years. The iodide is transported inside the thyroid epithelial cell via sodium iodide symporter (NIS) which is a trans-membrane protein. The present study was aimed to explore the uptake of radioiodide (RAI) and the expression of NIS in breast tissues of invasive ductal carcinoma patients. Breast tissues from tumor region (Tu-Br) as well as corresponding normal region (N-Br) were collected from patients of invasive ductal carcinoma. In vitro RAI uptake, its efflux and NIS expression were studied. The uptake of RAI (1.98+/-1.75 x 10(5) cpm/g) in Tu-Br was significantly higher as compared to that observed in N-Br (0.31+/-0.27 x 10(5) cpm/g) and fast efflux was observed in the tissue samples. NIS gene expression was positive in 41.66% (10/24) samples of Tu-Br. None of the N-Br samples expressed NIS gene. In 14 samples of Tu-Br, RAI uptake as well as NIS expression was studied. In 50% of these Tu-Br samples RAI uptake as well as of NIS gene expression was positive. The results indicate that RAI uptake is significantly higher in breast tumor tissues as compared to their normal counterpart and in future radioiodine may be an important agent for treatment of breast cancer.     

Expression of NA/1 symporter (NIS) in endometrial mucosa of fertile, sterile and post-menopausal women

The expression of the Na/I Symporter (NIS) in the basolateral cell membrane of the thyroid follicular cells is responsible for the active accumulation of iodide within the thyroid gland and for the subsequent biosynthesis of thyroid hormones. However, several tissues, such as salivary glands, breast, stomach, colon, ovary and endometrium, express NIS even if they are unable to organify iodide. In order to investigate a possible role of NIS in the endometrium, we analyzed, by immunochemistry, the expression of NIS in 44 endometrial samples of 20 patients with primary unexplained infertility, 14 fertile women and 10 in postmenopausal. NIS immunostaining was detected in endometrial cells belonging to the majority of sterile, post-menopausal and fertile women. However, the sterile and post-menopausal patients showed a higher percentage of NIS reactive cells compared to the fertile women (60+/-21% and 57+/-18% vs 19+/-9%; p=0.0001). NIS immunostaining was localized on the membrane and cytoplasm of the endometrial cells. We could not find any correlation between endometrial thickness and NIS immunoexpression. Our results indicate that, in the absence of histological markers, a sterile endometrium can be recognized because of the high expressions of NIS. Moreover, NIS expressions, elevated in both sterile and menopause women, is not related to the estrogen levels, but it could be modulated by factors common to the two conditions. In conclusion, we speculate that NIS may play a role in the development of female sterility.     

Novel glycosylation reactions using glycosyl thioimidates of N-acetylneuraminic acid as sialyl donors

Novel sialyl donors 4 bearing a thioimidolyl moiety as the leaving group were successfully prepared from the corresponding arylthio derivatives 3 and a peracetylated chloro derivative of Neu5Ac 2 in the presence of N,N-di-isopropylethylamine with moderate yields. The reaction of 4 with various alcohols 5 was effectively activated by AgOTf as the promoter to give the corresponding O-sialosides 6 with good yields. Selective activation of 4a over 4-pentenyl 2-glycoside of Neu5Ac 7 with AgOTf was also achieved.     

Role of commercial harbours and recreational marinas in the spread of non-indigenous fouling species

The role of commercial harbours as sink and source habitats for non-indigenous species (NIS) and the role of recreational boating for their secondary spread were investigated by analysing the fouling community of five Italian harbours and five marinas in the western Mediterranean Sea. It was first hypothesised that NIS assemblages in the recreational marinas were subsets of those occurring in commercial harbours. However, the data did not consistently support this hypothesis: the NIS pools of some marinas significantly diverged from harbours even belonging to the same coastal stretches, including NIS occurring only in marinas. This study confirms harbours as hotspots for marine NIS, but also reveals that numbers of NIS in some marinas is higher than expected, suggesting that recreational vessels effectively facilitate NIS spread. It is recommended that this vector of NIS introduction is taken into account in the future planning of sustainable development of maritime tourism in Europe.     

Non-Indigenous Species and Ecological Explanation

Within the last 20 years, the US has mounted amassive campaign against invasions bynon-indigenous species (NIS) such as zebramussels, kudzu, water hyacinths, and brown treesnakes. NIS have disrupted native ecosystemsand caused hundreds of billions of dollars ofannual damage. Many in the scientificcommunity say the problem of NIS is primarilypolitical and economic: getting governments toregulate powerful vested interests thatintroduce species through such vehicles asships' ballast water. This paper argues that,although politics and economics play a role,the problem is primarily one of scientificmethod. Even if commercial interests werewilling to spend the necessary funds to controlNIS, and even if government were willing toregulate them, ecological theory is notadequate to provide clear direction for eithereffort. The paper argues there is nocomprehensive, predictive theory ofinvasibility, as part of a larger theory ofcommunity structure, that might guideecological decision making regarding NIS, andfor at least three reasons. (1) There is nofirm definition of NIS, native, exotic,and so on, and ecologists do not use the termsconsistently; as a result, biologists debatingvarious accounts of community structure andecological explanation often do not even makelogical contact with each other. (2) Thedominant theory used to understandinvasibility, island biogeography, has noprecise predictive power and is unable toclarify when NIS might promote biodiversity andwhen they might hinder it. (3) There are nofirm, empirical generalizations that revealwhen a colonizer or a NIS might be likely totake over a new environment, and when it mightnot succeed in doing so. As a result,scientists have only rough rules of thumb toshore up their arguments against NIS. Given theincompleteness of current ecological theory,the paper closes with several suggestions forways that study of NIS might enhanceunderstanding of basic commmunity structuresand vice versa.