Specific transport of temozolomide does not override DNA repair-mediated chemoresistance

Temozolomide (TMZ) a DNA alkylating agent, is the standard-of-care for brain tumors, such as glioblastoma multiforme (GBM). Although the physicochemical and pharmacokinetic properties of TMZ, such as chemical stability and the ability to cross the blood-brain barrier (BBB), have been questioned in the past, the acquired chemoresistance has been the main limiting factor of long-term clinical use of TMZ. In the present study, an L-type amino acid transporter 1 (LAT1)-utilizing prodrug of TMZ (TMZ-AA, 6) was prepared and studied for its cellular accumulation and cytotoxic properties in human squamous cell carcinoma, UT-SCC-28 and UT-SCC-42B cells, and TMZ-sensitive human glioma, U-87MG cells that expressed functional LAT1. TMZ-AA 6 accumulated more effectively than TMZ itself into those cancer cells that expressed LAT1 (UT-SCC-42B). However, this did not correlate with decreased viability of treated cells. Indeed, TMZ-AA 6, similarly to TMZ itself, required adjuvant inhibitor(s) of DNA-repair systems, O6-methylguanine-DNA methyl transferase (MGMT) and base excision repair (BER), as well as active DNA mismatch repair (MMR), for maximal growth inhibition. The present study shows that improving the delivery of this widely-used methylating agent is not the main barrier to improved chemotherapy, although utilizing a specific transporter overexpressed at the BBB or glioma cells can have targeting advantages. To obtain a more effective anticancer prodrug, the compound design focus should shift to altering the major DNA alkylation site or inhibiting DNA repair systems.

Amino acid derivative of probenecid potentiates apoptosis-inducing effects of vinblastine by increasing oxidative stress in a cancer cell-specific manner

Many chemotherapeutic drugs suffer from multidrug resistance (MDR). Efflux transporters, namely ATP-binding cassettes (ABCs), that pump the drugs out of the cancer cells comprise one major reason behind MDR. Therefore, ABC inhibitors have been under development for ages, but unfortunately, without clinical success. In the present study, an l-type amino acid transporter 1 (LAT1)-utilizing derivative of probenecid (PRB) was developed as a cancer cell-targeted efflux inhibitor for P-glycoprotein (P-gp), breast cancer resistant protein (BCRP) and/or several multidrug resistant proteins (MRPs), and its ability to increase vinblastine (VBL) cellular accumulation and apoptosis-inducing effects were explored. The novel amino acid derivative of PRB (2) increased the VBL exposure in triple-negative human breast cancer cells (MDA-MB-231) and human glioma cells (U-87MG) by 10-68 -times and 2-5-times, respectively, but not in estrogen receptor-positive human breast cancer cells (MCF-7). However, the combination therapy had greater cytotoxic effects in MCF-7 compared to MDA-MB-231 cells due to the increased oxidative stress recorded in MCF-7 cells. The metabolomic study also revealed that compound 2, together with VBL, decreased the transport of those amino acids essential for the biosynthesis of endogenous anti-oxidant glutathione (GSH). Moreover, the metabolic differences between the outcomes of the studied breast cancer cell lines were explained by the distinct expression profiles of solute carriers (SLCs) that can be concomitantly inhibited. Therefore, attacking several SLCs simultaneously to change the nutrient environment of cancer cells can serve as an adjuvant therapy to other chemotherapeutics, offering an alternative to ABC inhibitors.

Sodium-Dependent Neutral Amino Acid Transporter 2 Can Serve as a Tertiary Carrier for l-Type Amino Acid Transporter 1-Utilizing Prodrugs

Membrane transporters are the key determinants of the homeostasis of endogenous compounds in the cells and their exposure to drugs. However, the substrate specificities of distinct transporters can overlap. In the present study, the interactions of l-type amino acid transporter 1 (LAT1)-utilizing prodrugs with sodium-coupled neutral amino acid transporter 2 (SNAT2) were explored. The results showed that the cellular uptake of LAT1-utilizing prodrugs into a human breast cancer cell line, MCF-7 cells, was mediated via SNATs as the uptake was increased at higher pH (8.5), decreased in the absence of sodium, and inhibited in the presence of unselective SNAT-inhibitor, (α-(methylamino)isobutyric acid, MeAIB). Moreover, docking the compounds to a SNAT2 homology model (inward-open conformation) and further molecular dynamics simulations and the subsequent trajectory and principal component analyses confirmed the chemical features supporting the interactions of the studied compounds with SNAT2, which was found to be the main SNAT expressed in MCF-7 cells.

Increased/Targeted Brain (Pro)Drug Delivery via Utilization of Solute Carriers (SLCs)

Membrane transporters have a crucial role in compounds’ brain drug delivery. They allow not only the penetration of a wide variety of different compounds to cross the endothelial cells of the blood–brain barrier (BBB), but also the accumulation of them into the brain parenchymal cells. Solute carriers (SLCs), with nearly 500 family members, are the largest group of membrane transporters. Unfortunately, not all SLCs are fully characterized and used in rational drug design. However, if the structural features for transporter interactions (binding and translocation) are known, a prodrug approach can be utilized to temporarily change the pharmacokinetics and brain delivery properties of almost any compound. In this review, main transporter subtypes that are participating in brain drug disposition or have been used to improve brain drug delivery across the BBB via the prodrug approach, are introduced. Moreover, the ability of selected transporters to be utilized in intrabrain drug delivery is discussed. Thus, this comprehensive review will give insights into the methods, such as computational drug design, that should be utilized more effectively to understand the detailed transport mechanisms. Moreover, factors, such as transporter expression modulation pathways in diseases that should be taken into account in rational (pro)drug development, are considered to achieve successful clinical applications in the future.

The Role of Transporters in Future Chemotherapy

The expression of membrane transporter is often altered in cancer cells compared to their corresponding healthy cells. Since these proteins, classified into solute carriers (SLCs) and ATP-binding cassettes (ABCs), can carry not only endogenous compounds, nutrients, and metabolites, but also drugs across the cell membranes, they have a crucial role in drug exposure and clinical outcomes of chemotherapeutics. Curiously, up-regulation of SLCs can be exploited to deliver chemotherapeutics, their prodrugs, and diagnostic radio-tracers to gain cancer cell-selective targeting, as exemplified with L-type amino acid transporter 1 (LAT1). SLCs can also be inhibited to limit the nutrient uptake of cancer cells and thus, cell growth and proliferation. Furthermore, LAT1 can be utilized to deliver ABC-inhibitors selectively into the cancer cells to block the efflux of other chemotherapeutics suffering from acquired or intrinsic efflux transport-related multidrug resistance (MDR). Taking into account the current literature, compounds that can affect transporter up- or down-regulation of transporters in a cancer cell-selective manner could be a valuable tool and promising chemotherapy form in the future.

Sulfonamide metformin derivatives induce mitochondrial-associated apoptosis and cell cycle arrest in breast cancer cells

Metformin, an oral anti-diabetic drug, has attracted scientific attention due to its anti-cancer effects. This biguanide exerts preventive effects against cancer, and interferes with cancer-promoting signaling pathways at the cellular level. However, the direct cytotoxic or anti-proliferative effect of the drug is observed at very high concentrations, often exceeding 5-10 mM. This paper presents the synthesis of eight novel sulfonamide-based biguanides with improved cellular uptake in two breast cancer cell lines (MCF-7 and MDA-MB-231), and evaluates their effects on cancer cell growth. The synthesized sulfonamide-based analogues of metformin (1-5) were efficiently taken up in MCF-7 and MDA-MB-231 cells, and were characterized by stronger cytotoxic properties than those of metformin. Generally, compounds were more effective in MCF-7 than in MDA-MB-231. Compound 2, with an n-octyl chain, was the most active molecule with IC₅₀ = 114.0 μmol/L in MCF-7 cells. The cytotoxicity of compound 2 partially results from its ability to induce early and late apoptosis. Increased intracellular reactive oxygen species (ROS) production and reduced mitochondrial membrane potential suggest that compound 2 promotes mitochondrial dysfunction and activates the mitochondrial-associated apoptosis-signaling pathway. In addition, compound 2 was also found to arrest cell cycle in the G0/G1 and G2/M phase and significantly inhibit cancer cell migration. In conclusion, this study supports the hypothesis that improved transporter-mediated cellular uptake of potential drug molecule is accompanied by its increased cytotoxicity. Therefore, compound 2 is a very good example of how chemical modification of a biguanide scaffold can affect its biological properties and improve anti-neoplastic potential.

Comparison of Experimental Strategies to Study l-Type Amino Acid Transporter 1 (LAT1) Utilization by Ligands

l-Type amino acid transporter 1 (LAT1), expressed abundantly in the brain and placenta and overexpressed in several cancer cell types, has gained a lot of interest in drug research and development, as it can be utilized for brain-targeted drug delivery, as well as inhibiting the essential amino acid supply to cancer cells. The structure of LAT1 is today very well-known and the interactions of ligands at the binding site of LAT1 can be modeled and explained. However, less is known of LAT1′s life cycle within the cells. Moreover, the functionality of LAT1 can be measured by several different methods, which may vary between the laboratories and make the comparison of the results challenging. In the present study, the usefulness of indirect cis-inhibition methods and direct cellular uptake methods and their variations to interpret the interactions of LAT1-ligands were evaluated. Moreover, this study also highlights the importance of understanding the intracellular kinetics of LAT1-ligands, and how they can affect the regular function of LAT1 in critical tissues, such as the brain. Hence, it is discussed herein how the selected methodology influences the outcome and created knowledge of LAT1-utilizing compounds.

Hemocompatible LAT1-inhibitor can induce apoptosis in cancer cells without affecting brain amino acid homeostasis

Increased amounts of amino acids are essential for cancer cells to support their sustained growth and survival. Therefore, inhibitors of amino acid transporters, such as l-type amino acid transporter 1 (LAT1) have been developed. In this study, a previously reported LAT1-inhibitor (KMH-233) was studied for its hemocompatibility and toxicity towards human umbilical vein endothelial cells (HUVEC) and human aortic smooth muscle cells (AoSMCs). Furthermore, the cytotoxic effects against human breast adenocarcinoma cells (MCF-7) and its ability to affect mammalian (or mechanistic) target of rapamycin (mTOR) and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling were evaluated. Moreover, the effects of this inhibitor to modulate LAT1 function on the cell surface and the brain amino acid homeostasis were evaluated after intraperitoneal (i.p.) administration of LAT1-inhibitor (23 µmol/kg) in mice. The results showed that LAT1-inhibitor (KMH-233) is hemocompatible at concentrations below 25 µM and it does not affect coagulation in plasma. However, it can reduce the total protein amount of mTOR and NF-κB, resulting in increased apoptosis in LAT1-expressing cancer cells. Most importantly, the inhibitor did not affect mouse brain levels of l-Leu, l-Tyr or l-Trp or modulate the function of LAT1 on the MCF-7 cell surface. Therefore, this inhibitor can be considered as a safe but effective anti-cancer agent. However, due to the compensative mechanism of cancer cells for their increased amino acid demand, this compound is most effective inducing apoptosis when used in combinations with other chemotherapeutics, such as protease inhibitor, bestatin, as demonstrated in this study.

Improved l-Type amino acid transporter 1 (LAT1)-mediated delivery of anti-inflammatory drugs into astrocytes and microglia with reduced prostaglandin production

Non-steroidal anti-inflammatory drugs (NSAIDs) can have protective effects in the brain by inhibition of cyclooxygenases (COX). However, the delivery into the brain across the blood-brain barrier (BBB) and particularly into the brain parenchymal cells is hindered. Therefore, in the present study, we developed four l-type amino acid transporter 1 (LAT1)-utilizing prodrugs of flurbiprofen, ibuprofen, naproxen, and ketoprofen, since LAT1 is expressed on both, the BBB endothelial cells as well as parenchymal cells. The cellular uptake and utilization of LAT1 by novel prodrugs were studied in mouse cortical primary astrocytes and immortalized microglia (BV2), and the release of the parent NSAID in several tissue and cell homogenates. Finally, the effects of the studied prodrugs on prostaglandin E₂ (PGE₂) production and cell viability were explored. The gained results showed that all four prodrugs were carried into their target cells via LAT1. They also released their parent NSAIDs via carboxylesterases (CES) and most likely also other un-identified enzymes, which need to be carefully considered when administrating these compounds orally or intravenously. Most importantly, all the studied prodrugs reduced the PGE₂ production in astrocytes and microglia after lipopolysaccharide (LPS)-induced inflammation by 29-94% and without affecting the cell viability with the studied concentration (20 µM).

L-Type Amino Acid Transporter 1 Enables the Efficient Brain Delivery of Small-Sized Prodrug across the Blood-Brain Barrier and into Human and Mouse Brain Parenchymal Cells

Membrane transporters have long been utilized to improve the oral, hepatic, and renal (re)absorption. In the brain, however, the transporter-mediated drug delivery has not yet been fully achieved due to the complexity of the blood-brain barrier (BBB). Because L-type amino acid transporter 1 (LAT1) is a good candidate to improve the brain delivery, we developed here four novel LAT1-utilizing prodrugs of four nonsteroidal anti-inflammatory drugs. As a result, all the prodrugs were able to cross the BBB and localize into the brain cells. The brain uptake of salicylic acid (SA) was improved five times, not only across the mouse BBB but also into the cultured mouse and human brain cells. The naproxen prodrug was also transported efficiently into the mouse brain achieving less peripheral exposure, but the brain release of naproxen from the prodrug was not improved. Contrarily, the high plasma protein binding of the flurbiprofen prodrug and the premature bioconversion of the ibuprofen prodrug in the mouse blood hindered the efficient brain delivery. Thus, the structure of the parent drug affects the successful brain delivery of the LAT1-utilizing prodrugs, and the small-sized LAT1-utilizing prodrug of SA constituted a successful model to specifically deliver its parent drug across the mouse BBB and into the cultured mouse and human brain cells.

Effective Cellular Transport of Ortho-Halogenated Sulfonamide Derivatives of Metformin Is Related to Improved Antiproliferative Activity and Apoptosis Induction in MCF-7 Cells

Metformin is a substrate for plasma membrane monoamine transporters (PMAT) and organic cation transporters (OCTs); therefore, the expression of these transporters and interactions between them may affect the uptake of metformin into tumor cells and its anticancer efficacy. The aim of this study was to evaluate how chemical modification of metformin scaffold into benzene sulfonamides with halogen substituents (compounds 1-9) may affect affinity towards OCTs, cellular uptake in two breast cancer cell lines (MCF-7 and MDA-MB-231) and antiproliferative efficacy of metformin. The uptake of most sulfonamides was more efficient in MCF-7 cells than in MDA-MB-231 cells. The presence of a chlorine atom in the aromatic ring contributed to the highest uptake in MCF-7 cells. For instance, the uptake of compound 1 with o-chloro substituent in MCF-7 cells was 1.79 ± 0.79 nmol/min/mg protein, while in MDA-MB-231 cells, the uptake was considerably lower (0.005 ± 0.0005 nmol/min/mg protein). The elevated uptake of tested compounds in MCF-7 was accompanied by high antiproliferative activity, with compound 1 being the most active (IC50 = 12.6 ± 1.2 µmol/L). Further studies showed that inhibition of MCF-7 growth is associated with the induction of early and late apoptosis and cell cycle arrest at the G0/G1 phase. In summary, the chemical modification of the biguanide backbone into halogenated sulfonamides leads to improved transporter-mediated cellular uptake in MCF-7 and contributes to the greater antiproliferative potency of studied compounds through apoptosis induction and cell cycle arrest.

L-Type Amino Acid Transporter 1 (LAT1/Lat1)-Utilizing Prodrugs Can Improve the Delivery of Drugs into Neurons, Astrocytes and Microglia

l-Type Amino Acid Transporter 1 (LAT1/Lat1) is responsible for carrying large, neutral l-amino acids as well as several drugs and prodrugs across the blood-brain barrier (BBB). However, the BBB is not the only barrier that hinders drugs acting effectively within the brain; the brain parenchymal cell membranes represent a secondary barrier for the drugs with intracellular target sites. In this study, expression and function of Lat1 was quantified in mouse primary neuron, astrocyte and immortalized microglia (BV2) cultures. Moreover, ability of Lat1 to carry prodrugs inside these brain cells was evaluated. The results showed that Lat1 was localized at the similar level in all studied cells (3.07 ± 0.92–3.77 ± 0.91 fmol/µg protein). The transporter was also functional in all three cell types, astrocytes having the highest transport capacity and affinity for the LAT1/Lat1-substrate, [¹⁴C]-l-leucine, followed by neurons and microglia. The designed prodrugs (1-6) were able to utilize Lat1 for their cellular uptake and it was mainly much higher than the one of their parent drugs. Interestingly, improved cellular uptake was also achieved in cells representing Alzheimer’s Disease phenotype. Therefore, improved delivery and intra-brain targeting of drugs can be attained by utilizing LAT1/Lat1 and prodrug approach.

Sulfenamide derivatives can improve transporter-mediated cellular uptake of metformin and induce cytotoxicity in human breast adenocarcinoma cell lines

Metformin, the most frequently administered oral anti-diabetic drug, is a substrate for organic cation transporters (OCTs). This determines not only its pharmacokinetic properties but also its biochemical effects in humans, including its recently-discovered antiproliferative properties. The aim of the study was to verify the hypothesis whether chemical modification of its biguanide backbone may increase the cellular uptake and antiproliferative efficacy of metformin. The study examines five sulfenamide derivatives of metformin with differing lengths of alkyl chains. It determines their cellular uptake and the role of OCTs in their transport in human breast adenocarcinoma cells (epithelial-like MCF-7, and MDA-MB-231). It also evaluates whether increased cellular uptake of metformin derivatives is associated with their cytotoxic properties. Sulfenamide derivatives were characterized by a greater ability to bind to OCTs than metformin. Compound 2 with n-octyl alkyl chain was found to possess the greatest affinity towards OCTs, as measured by determination of [¹⁴C]choline uptake inhibition (IC₅₀ = 236.1 ± 1.28 μmol/L, and 217.4 ± 1.33 μmol/L, for MCF-7 and MDA-MB-231 respectively). Sulfenamides were also found to exhibit better cellular uptake in comparison with the parent drug, metformin. For instance, the uptake of cyclohexyl derivative 1 was 1.28 ± 0.19 nmol/min/mg of proteins and thus was 12-fold higher than the metformin in MCF-7 cells. Furthermore, higher uptake was associated with the greatest antiproliferative properties expressed as the lowest IC₅₀ value i.e. inhibiting the growth of 50% of the cells (IC₅₀ = 0.72 ± 1.31 μmol/L). Collectively, chemical modification of metformin into sulfenamides with different alkyl substituents obtains better substrates for OCTs, and subsequently higher cellular uptake in MCF-7 and MDA-MB-231 cells. Additionally, the length of alkyl chain introduced to the sulfenamides was found to influence selectivity and transport efficiency via OCT1 compared to other possible transporters, as well as potential intracellular activity and cytotoxicity.

Targeted efflux transporter inhibitors - A solution to improve poor cellular accumulation of anti-cancer agents

Efflux transporters function as vacuum cleaners of xenobiotics and therefore they hinder drugs to reach their targets at effective enough concentrations. Efflux pump inhibitors can be used to improve the cell accumulation of drugs, however all the current inhibitors lack selectivity towards cancer cells. l-Type amino acid transporter 1 (LAT1), which is expressed in many types of cancer cells can be utilized to target inhibitors of efflux transporters to these cells by converting the inhibitors into LAT1-utilizing prodrugs. In this study, we prepared 5 LAT1-utilizing prodrugs of an efflux pump inhibitor, probenecid (PRB). All novel compounds were transported into human breast cancer cells (MCF-7) mainly via LAT1. The compounds also interacted with either multiresistant proteins (MRPs), P-glycoprotein (P-gp) or breast cancer resistant protein (BCRP) and increased significantly (3-4-fold) the cellular accumulation of anti-cancer agent vinblastine (VBL). Consequently, this improved the anti-proliferative efficacy of VBL by decreasing the cell growth after 72 h from 100% (VBL treatment alone) to 48-75% (combination treatment). However, the same phenomenon was not seen with other chemotherapeutic, methotrexate (MTX). Therefore, the chemotherapeutics need to be selected carefully based on their uptake mechanism to the combinations with LAT1-utilizing prodrugs of efflux pump inhibitors to defeat effectively the multidrug resistance (MDR) of chemotherapy.

Increased Mortality Despite Successful Multifactorial Cardiovascular Risk Reduction in Healthy Men: 40-Year Follow-Up of the Helsinki Businessmen Study Intervention Trial

OBJECTIVES

In a 5-year multifactorial risk reduction intervention for healthy men with at least one cardiovascular disease (CVD) risk factor, mortality was unexpectedly higher in the intervention than the control group during the first 15-year follow-up. In order to find explanations for the adverse outcome, we have extended mortality follow-up and examined in greater detail baseline characteristics that contributed to total mortality.

DESIGN

Long-term follow-up of a controlled intervention trial.

SETTING

The Helsinki Businessmen Study Intervention Trial.

PARTICIPANTS AND INTERVENTION

The prevention trial between 1974-1980 included 1,222 initially healthy men (born 1919-1934) at high CVD risk, who were randomly allocated into intervention (n=612) and control groups (n=610). The 5-year multifactorial intervention consisted of personal health education and contemporary drug treatments for dyslipidemia and hypertension. In the present analysis we used previously unpublished data on baseline risk factors and lifestyle characteristics.

MAIN OUTCOME MEASURES

40-year total and cause-specific mortality through linkage to nation-wide death registers.

RESULTS

The study groups were practically identical at baseline in 1974, and the 5-year intervention significantly improved risk factors (body mass index, blood pressure, serum lipids and glucose), and total CVD risk by 46% in the intervention group. Despite this, total mortality has been consistently higher up to 25 years post-trial in the intervention group than the control group, and converging thereafter. Increased mortality risk was driven by CVD and accidental deaths. Of the newly-analysed baseline factors, there was a significant interaction for mortality between intervention group and yearly vacation time (P=0.027): shorter vacation was associated with excess 30-year mortality in the intervention (hazard ratio 1.37, 95% CI 1.03-1.83, P=0.03), but not in the control group (P=0.5). This finding was robust to multivariable adjustments.

CONCLUSION

After a multifactorial intervention for healthy men with at least one CVD risk factor, there has been an unexpectedly increased mortality in the intervention group. This increase was especially observed in a subgroup characterised by shorter vacation time at baseline. Although this adverse response to personal preventive measures in vulnerable individuals may be characteristic to men of high social status with subclinical CVD, it clearly deserves further investigation.

A Selective and Slowly Reversible Inhibitor of l-Type Amino Acid Transporter 1 (LAT1) Potentiates Antiproliferative Drug Efficacy in Cancer Cells

The l-type amino acid transporter 1 (LAT1) is a transmembrane protein carrying bulky and neutral amino acids into cells. LAT1 is overexpressed in several types of tumors, and its inhibition can result in reduced cancer cell growth. However, known LAT1 inhibitors lack selectivity over other transporters. In the present study, we designed and synthesized a novel selective LAT1 inhibitor (1), which inhibited the uptake of LAT1 substrate, l-leucin as well as cell growth. It also significantly potentiated the efficacy of bestatin and cisplatin even at low concentrations (25 μM). Inhibition was slowly reversible, as the inhibitor was able to be detached from the cell surface and blood-brain barrier. Moreover, the inhibitor was metabolically stable and selective toward LAT1. Since the inhibitor was readily accumulated into the prostate after intraperitoneal injection to the healthy mice, this compound may be a promising agent or adjuvant especially for the treatment of prostate cancer.

ViPAR: a software platform for the Virtual Pooling and Analysis of Research Data

Background: Research studies exploring the determinants of disease require sufficient statistical power to detect meaningful effects. Sample size is often increased through centralized pooling of disparately located datasets, though ethical, privacy and data ownership issues can often hamper this process. Methods that facilitate the sharing of research data that are sympathetic with these issues and which allow flexible and detailed statistical analyses are therefore in critical need. We have created a software platform for the Virtual Pooling and Analysis of Research data (ViPAR), which employs free and open source methods to provide researchers with a web-based platform to analyse datasets housed in disparate locations.

Methods: Database federation permits controlled access to remotely located datasets from a central location. The Secure Shell protocol allows data to be securely exchanged between devices over an insecure network. ViPAR combines these free technologies into a solution that facilitates ‘virtual pooling’ where data can be temporarily pooled into computer memory and made available for analysis without the need for permanent central storage.

Results: Within the ViPAR infrastructure, remote sites manage their own harmonized research dataset in a database hosted at their site, while a central server hosts the data federation component and a secure analysis portal. When an analysis is initiated, requested data are retrieved from each remote site and virtually pooled at the central site. The data are then analysed by statistical software and, on completion, results of the analysis are returned to the user and the virtually pooled data are removed from memory.

Conclusions: ViPAR is a secure, flexible and powerful analysis platform built on open source technology that is currently in use by large international consortia, and is made publicly available at [ http://bioinformatics.childhealthresearch.org.au/software/vipar/ ].

Quality indicators for the prevention of type 2 diabetes in Europe--IMAGE

BACKGROUND

The marked increase of type 2 diabetes necessitates active development and implementation of efficient prevention programs. A European level action has been taken by launching the IMAGE project to unify and improve the various prevention management concepts, which currently exist within the EU. This report describes the background and the methods used in the development of the IMAGE project quality indicators for diabetes primary prevention programs. It is targeted to the persons responsible for diabetes prevention at different levels of the health care systems.

METHODS

Development of the quality indicators was conducted by a group of specialists representing different professional groups from several European countries. Indicators and measurement recommendations were produced by the expert group in consensus meetings and further developed by combining evidence and expert opinion.

RESULTS

The quality indicators were developed for different prevention strategies: population level prevention strategy, screening for high risk, and high risk prevention strategy. Totally, 22 quality indicators were generated. They constitute the minimum level of quality assurance recommended for diabetes prevention programs. In addition, 20 scientific evaluation indicators with measurement standards were produced. These micro level indicators describe measurements, which should be used if evaluation, reporting, and scientific analysis are planned.

CONCLUSIONS

We hope that these quality tools together with the IMAGE guidelines will provide a useful tool for improving the quality of diabetes prevention in Europe and make different prevention approaches comparable.

Take action to prevent diabetes--the IMAGE toolkit for the prevention of type 2 diabetes in Europe

When we ask people what they value most, health is usually top of the list. While effective care is available for many chronic diseases, the fact remains that for the patient, the tax payer and the whole of society: prevention is better than cure. Diabetes and its complications are a serious threat to the survival and well-being of an increasing number of people. It is predicted that one in ten Europeans aged 20-79 will have developed diabetes by 2030. Once a disease of old age, diabetes is now common among adults of all ages and is beginning to affect adolescents and even children. Diabetes accounts for up to 18 % of total healthcare expenditure in Europe. The good news is that diabetes is preventable. Compelling evidence shows that the onset of diabetes can be prevented or delayed greatly in individuals at high risk (people with impaired glucose regulation). Clinical research has shown a reduction in risk of developing diabetes of over 50 % following relatively modest changes in lifestyle that include adopting a healthy diet, increasing physical activity, and maintaining a healthy body weight. These results have since been reproduced in real-world prevention programmes. Even a delay of a few years in the progression to diabetes is expected to reduce diabetes-related complications, such as heart, kidney and eye disease and, consequently, to reduce the cost to society. A comprehensive approach to diabetes prevention should combine population based primary prevention with programmes targeted at those who are at high risk. This approach should take account of the local circumstances and diversity within modern society (e.g. social inequalities). The challenge goes beyond the healthcare system. We need to encourage collaboration across many different sectors: education providers, non-governmental organisations, the food industry, the media, urban planners and politicians all have a very important role to play. Small changes in lifestyle will bring big changes in health. Through joint efforts, more people will be reached. The time to act is now.

A European evidence-based guideline for the prevention of type 2 diabetes

BACKGROUND

The prevalence and socioeconomic burden of type 2 diabetes (T2DM) and associated co-morbidities are rising worldwide.

AIMS

This guideline provides evidence-based recommendations for preventing T2DM.

METHODS

A European multidisciplinary consortium systematically reviewed the evidence on the effectiveness of screening and interventions for T2DM prevention using SIGN criteria.

RESULTS

Obesity and sedentary lifestyle are the main modifiable risk factors. Age and ethnicity are non-modifiable risk factors. Case-finding should follow a step-wise procedure using risk questionnaires and oral glucose tolerance testing. Persons with impaired glucose tolerance and/or fasting glucose are at high-risk and should be prioritized for intensive intervention. Interventions supporting lifestyle changes delay the onset of T2DM in high-risk adults (number-needed-to-treat: 6.4 over 1.8-4.6 years). These should be supported by inter-sectoral strategies that create health promoting environments. Sustained body weight reduction by >or= 5 % lowers risk. Currently metformin, acarbose and orlistat can be considered as second-line prevention options. The population approach should use organized measures to raise awareness and change lifestyle with specific approaches for adolescents, minorities and disadvantaged people. Interventions promoting lifestyle changes are more effective if they target both diet and physical activity, mobilize social support, involve the planned use of established behaviour change techniques, and provide frequent contacts. Cost-effectiveness analysis should take a societal perspective.

CONCLUSIONS

Prevention using lifestyle modifications in high-risk individuals is cost-effective and should be embedded in evaluated models of care. Effective prevention plans are predicated upon sustained government initiatives comprising advocacy, community support, fiscal and legislative changes, private sector engagement and continuous media communication.

Effect of guar gum on body weight and serum lipids in hypercholesterolemic females

The effect of guar gum (15 g/day) on serum lipids and body weight of middle-aged hypercholesterolemic females was studied in a double-blind controlled trial. No consistent changes were observed in serum cholesterol, triglycerides or HDL cholesterol in patients taking guar gum, placebo or no medication at all. A highly significant decrease in body weight (62.9 +/- 2.1 vs. 60.4 +/- 2.2 kg, p < 0.0005, paired comparison) was seen in subjects receiving guar gum, whereas body weight remained constant in the other two groups. It is concluded that the daily ingestion of 15 g of guar gum results in a permanent weight loss, but does not influence serum lipids in females with hypercholesterolemia.

Superresolution ultrasound imaging using back-projected reconstruction

An ultrasound technique for imaging objects significantly smaller than the source wavelength is investigated. Signals from a focused beam are recorded over an image plane in the acoustic farfield and backprojected in the wave-vector domain to the focal plane. A superresolution image recovery method is then used to analyze the Fourier spatial frequency spectrum of the signal in an attempt to deduce the location and size of objects in this plane. The physical foundation for the method is rooted in the fact that high spatial frequencies introduced by the object in fact affect the lower (nonevanescent) spatial frequencies of the overall signal. The technique achieves this by using a priori measurements of the ultrasound focus in water, which gives full spectral information about the image source. A guess is then made regarding the size and location of the object that distorted the field, and this is convolved with the a priori measurement, thus creating a candidate image. A large number of candidates are generated and the one whose spectrum best matches the uncorrected image is accepted. The method is demonstrated using 0.34- and 0.60-mm wires with a focused 1.05-MHz ultrasound signal and then a human hair (approximately 0.03 mm) with a 4.7-MHz signal.

Abnormal crossing of the optic fibres shown by evoked magnetic fields in patients with ocular albinism with a novel mutation in the OA1 gene

AIM

To perform genealogical and clinical studies in Finnish families with X linked ocular albinism (OA1), including characterisation of the potential misrouting of optic fibres by evaluating visual evoked magnetic fields (VEFs), and to determine the mutation behind the disease.

METHODS

Three families with OA1 were clinically examined. VEFs were measured in two affected males and in one female carrier to characterise the cortical activation pattern after monocular visual stimulation. The neuronal sources of the VEFs were modelled with equivalent current dipoles (ECDs) in a spherical head model. All coding exons of the OA1 gene were screened for mutations by single strand conformation analysis and direct polymerase chain reaction sequencing.

RESULTS

Genealogical studies revealed that the three families were all related. The affected males had foveal hypoplasia with reduced visual acuity varying from 20/200 to 20/50, variable nystagmus, iris transillumination, and hypopigmentation of the retinal pigment epithelium. The ECD locations corresponding to the VEFs revealed abnormal crossing of the optic fibres in both affected males, but not in the carrier female. A novel point mutation, leading to a STOP codon, was identified in the fifth exon of the OA1 gene.

CONCLUSIONS

The data indicate that the novel mutation 640C>T in the OA1 gene is the primary cause of the eye disease in the family studied. VEFs with ECD analysis was successfully used to demonstrate abnormal crossing of the optic fibres.

Interaction of mobile phones with superficial passive metallic implants

The dosimetry of exposure to radiofrequency (RF) electromagnetic (EM) fields of mobile phones is generally based on the specific absorption rate (SAR, W kg(-1)), which is the electromagnetic energy absorbed in the tissues per unit mass and time. In this study, numerical methods and modelling were used to estimate the effect of a passive, metallic (conducting) superficial implant on a mobile phone EM field and especially its absorption in tissues in the near field. Two basic implant models were studied: metallic pins and rings in the surface layers of the human body near the mobile phone. The aim was to find out 'the worst case scenario' with respect to energy absorption by varying different parameters such as implant location, orientation, size and adjacent tissues. Modelling and electromagnetic field calculations were carried out using commercial SEMCAD software based on the FDTD (finite difference time domain) method. The mobile phone was a 900 MHz or 1800 MHz generic phone with a quarter wave monopole antenna. A cylindrical tissue phantom models different curved sections of the human body such as limbs or a head. All the parameters studied (implant size, orientation, location, adjacent tissues and signal frequency) had a major effect on the SAR distribution and in certain cases high local EM fields arose near the implant. The SAR values increased most when the implant was on the skin and had a resonance length or diameter, i.e. about a third of the wavelength in tissues. The local peak SAR values increased even by a factor of 400-700 due to a pin or a ring. These highest values were reached in a limited volume close to the implant surface in almost all the studied cases. In contrast, without the implant the highest SAR values were generally reached on the skin surface. Mass averaged SAR(1 g) and SAR(10 g) values increased due to the implant even by a factor of 3 and 2, respectively. However, at typical power levels of mobile phones the enhancement is unlikely to be problematic.

EEG minimum-norm estimation compared with MEG dipole fitting in the localization of somatosensory sources at S1

OBJECTIVE

Dipole models, which are frequently used in attempts to solve the electromagnetic inverse problem, require explicit a priori assumptions about the cerebral current sources. This is not the case for solutions based on minimum-norm estimates. In the present study, we evaluated the spatial accuracy of the L2 minimum-norm estimate (MNE) in realistic noise conditions by assessing its ability to localize sources of evoked responses at the primary somatosensory cortex (SI).

METHODS

Multichannel somatosensory evoked potentials (SEPs) and magnetic fields (SEFs) were recorded in 5 subjects while stimulating the median and ulnar nerves at the left wrist. A Tikhonov-regularized L2-MNE, constructed on a spherical surface from the SEP signals, was compared with an equivalent current dipole (ECD) solution obtained from the SEFs.

RESULTS

Primarily tangential current sources accounted for both SEP and SEF distributions at around 20 ms (N20/N20m) and 70 ms (P70/P70m), which deflections were chosen for comparative analysis. The distances between the locations of the maximum current densities obtained from MNE and the locations of ECDs were on the average 12-13 mm for both deflections and nerves stimulated. In accordance with the somatotopical order of SI, both the MNE and ECD tended to localize median nerve activation more laterally than ulnar nerve activation for the N20/N20m deflection. Simulation experiments further indicated that, with a proper estimate of the source depth and with a good fit of the head model, the MNE can reach a mean accuracy of 5 mm in 0.2-microV root-mean-square noise.

CONCLUSIONS

When compared with previously reported localizations based on dipole modelling of SEPs, it appears that equally accurate localization of S1 can be obtained with the MNE.

SIGNIFICANCE

MNE can be used to verify parametric source modelling results. Having a relatively good localization accuracy and requiring minimal assumptions, the MNE may be useful for the localization of poorly known activity distributions and for tracking activity changes between brain areas as a function of time.

PROD-screen--a screen for prodromal symptoms of psychosis

The aim of this study was to describe the PROD-screen, an instrument for screening prodromal symptoms indicating risk for psychotic conversion in the near future. PROD-screen consists of 29 questions assessing performance and symptoms. Clinical construct validity was tested by comparing scores from the unselected general population (GP, n = 64) with those of general psychiatric patients from a community mental health centre (CMHC, n = 107). The concordant validity of PROD-screen for prodromal symptoms of psychosis was assessed in a large epidemiologically mixed sample of research subjects (n = 132) by comparing PROD-screen scores with the prodromal diagnosis made by Structured Interview for Prodromal Symptoms as a gold standard. Using the cut-off point of 2/12 specific symptoms, PROD-screen gave correct classification of prodromal status in 77% of cases, distinguishing prodromal from non-prodromal subjects with reasonable sensitivity (80%) and specificity (75%) in the epidemiologically mixed sample. According to subsample analysis PROD-screen functions well with first-degree relatives of schizophrenic patients and probably also with general population samples, but not with psychiatric outpatients. In conclusion, PROD-screen is a useful tool for screening prodromal symptoms of psychosis and selecting subjects for more extensive research interviews.

Enlarged SI and SII somatosensory evoked responses in the CLN5 form of neuronal ceroid lipofuscinosis

OBJECTIVES

To examine in detail the activation of the primary (SI) and secondary (SII) somatosensory cortex in CLN5, the Finnish variant of late infantile neuronal ceroid lipofuscinoses (NCL).

METHODS

Somatory evoked magnetic fields were recorded with a 122-channel planar gradiometer in response to median nerve stimulation in 5 CLN5 patients (aged 8.8-16.7 years) and in 10 healthy age-matched controls.

RESULTS

The first two responses from contralateral SI, N20m and P35m, were 6-20 times stronger in the patients than in the controls. The morphology of the subsequent deflections from SI was abnormal in the patients: a prominent N45m was detected, while the normally present P60m deflection was missing. In 4 patients the contra- and in two patients the ipsilateral SII responses were also enlarged. Furthermore, the SII activation was detected at shorter latency in patients than in controls.

CONCLUSIONS

At SI, CLN5 is associated with a selective enhancement of the early cortical responses. We propose that the enlargement of N20m most likely reflects increased synchronous input from thalamus, whereas the altered morphology of the following responses may reflect defective interneuronal inhibition at the cortex. The enlargement of SII responses shows that the imbalance between excitation and inhibition in CLN5 extends outside the primary somatosensory areas.

Effects of haloperidol on selective attention: a combined whole-head MEG and high-resolution EEG study

We used 122-channel magnetoencephalography (MEG) and 64-channel electroencephalogrphy (EEG) simultaneously to study the effects of dopaminergic transmission on human selective attention in a randomized, double-blind placebo-controlled cross-over design. A single dose of dopamine D2 receptor antagonist haloperidol (2 mg) or placebo was given orally to 12 right-handed healthy volunteers 3 hours before measurement. In a dichotic selective attention task, subjects were presented with two trains of standard (700 Hz to the left ear, 1,100 Hz to the right ear) and deviant (770 and 1,210 Hz, respectively) tones. Subjects were instructed to count the tones presented to one ear; whereas, the tones presented to the other ear were to be ignored. Haloperidol significantly attenuated processing negativity (PN), an event-related potential (ERP) component elicited by selectively attended standard tones at 300-500 ms after stimulus presentation. These results, indicating impaired selective attention by a blockade of dopamine D2 receptors, were further accompanied with increased mismatch negativity (MMN), elicited by involuntary detection of task-irrelevant deviants. Taken together, haloperidol seemed to induce functional changes in neural networks accounting for both selective and involuntary attention, suggesting modulation of these functions by dopamine D2 receptors.

No evidence for dependence of early cortical auditory processing on dopamine D(2)-receptor modulation: a whole-head magnetoencephalographic study

Magnetoencephalography (MEG) was used to determine the effect of neuroleptic challenge on brain responses in healthy subjects. In a double-blind, randomized, placebo-controlled, cross-over design study, the dopamine D(2) receptor antagonist haloperidol (2 mg) was given orally to 12 healthy volunteers. The middle-latency auditory evoked magnetic fields (MAEF) were recorded 3 h after administration of haloperidol or placebo with a whole-head 122-channel MEG. Haloperidol did not significantly affect MAEF responses. The dipole moments and source locations of the responses were not significantly influenced by haloperidol. These results suggest that dopamine D(2) receptors are not involved in the early phases of auditory cortical processing.

Interhemispheric phase synchrony and amplitude correlation of spontaneous beta oscillations in human subjects: a magnetoencephalographic study

Interhemispheric phase synchrony and amplitude correlation of beta oscillations were studied with MEG in a resting condition. The left and right hemisphere beta oscillations exhibited phase-locking with a phase-lag near zero degrees. The index of synchronization was strongest when these oscillations had large amplitude. Functionally, we interpret the phase synchrony on the basis of bilaterality of movement organization. A positive interhemispheric correlation was also found for the amplitude of spontaneous beta oscillations over long time intervals (> 1 s). The low-frequency correlation of spontaneous rhythmic activity may be the source of the low-frequency correlations of the hemodynamic responses in homologous areas that have been reported previously and have been interpreted as functional connectivity between these areas.

Auditory sensory memory and the cholinergic system: implications for Alzheimer's disease

Auditory sensory memory represents one of the simplest types of short-term memory that can be studied electrophysiologically with mismatch negativity (MMN); a specific auditory event-related potential indexing automatic comparison of incoming stimuli to an existing memory trace. Previous results suggest that auditory sensory memory deteriorates in aging and especially in Alzheimer's disease (AD). It has remained unsettled, however, whether MMN is regulated by the cholinergic system, which is deteriorated in AD contributing to cognitive impairments. We recorded cortical auditory responses with a magnetometer from 13 healthy subjects after intravenous injection of scopolamine, centrally acting cholinergic antagonist, or glycopyrrolate, a drug with a peripheral anticholinergic properties without penetrating the blood-brain barrier, using a double-blind protocol. Scopolamine reduced MMNm amplitude in response to frequency, but not duration, change, increased P50m amplitude, and delayed N100m latency. These findings suggest that the cholinergic system regulates the frequency-specific comparison of incoming stimuli to existing memory trace and modulates the preattentive processing related to stimulus detection. Further, neural mechanisms responsible for cortical frequency- and duration-specific discrimination appear to have different sensitivities to cholinergic modulation. Auditory evoked potentials might be suitable to monitor cholinergic activity in AD.

Scopolamine reduces the P35m and P60m deflections of the human somatosensory evoked magnetic fields

Acetylcholine (ACh) is a potent neuromodulator in the brain with multiple, complex effects on neuronal function, most of which are mediated by muscarinic receptors. Generally, the most significant effect is excitation of pyramidal neurones and facilitation of responses to afferent stimulation. Much of the information on the ACh effects comes from studies utilizing in vitro or anesthetized in vivo preparations, while fewer data are available from awake animals or humans. We studied human somatosensory evoked magnetic fields (SEFs), which reflect summated postsynaptic currents in pyramidal neurones in area 3b, and in the opercular somatosensory cortex, when cholinergic transmission was modulated either by a central (scopolamine, 0.3 mg, i.v.) or peripheral (glycopyrrolate, 0.2 mg, i.v.) muscarinic antagonist. A randomized, double-blind, cross-over design was employed. SEFs were elicited by right median nerve stimulation at the wrist with constant-current pulses above motor threshold. The first excitatory cortical response from area 3b (N20m) was not affected by the central muscarinic blockade, while later P35m and P60m deflections were significantly reduced. The responses from the opercular somatosensory cortex showed some tendency toward reduction, but no significant alterations. The results show that somatosensory cortical processing can be modulated by muscarinic transmission at a relatively early stage. Relative membrane hyperpolarization of pyramidal neurons due to scopolamine (caused by blocking an ACh-induced tonic depolarization) is discussed as a possible mechanism underlying the observed effects.

The Schizophrenia Suicide Risk Scale (SSRS): development and initial validation

BACKGROUND

Estimations about the lifetime risk of suicide in schizophrenia vary between 4 and 10%. At present, there does not exist a suicide risk scale developed particularly for schizophrenic patients. The aims of the present study were to: (1) develop a clinically useful semi-structured scale for the estimation of short-term suicide risk among schizophrenic patients, and (2) to carry out an initial validation of the scale.

METHODS

A 25-item Schizophrenia Suicide Risk Scale (SSRS) was constructed on the base of the literature. The SSRS scores of 69 living schizophrenic patients (LS group) were compared with the scores of 69 schizophrenic suicides (SS group) whose data had been collected previously from The Finnish nationwide and representative psychological autopsy study. Internal consistency of the SSRS was evaluated with Cronbach alpha. The most important SSRS items predicting suicide were identified with a logistic regression analysis. Sensitivity, specificity, positive predictive value, and negative predictive value of the SSRS in predicting suicide with various cut-off scores were calculated.

RESULTS

In the final logistic regression model, the following SSRS items significantly predicted suicide: suicide plans communicated to someone during the past 3 months; one or more previous suicide attempts; loss of professional skills demanding job; depression observed during an interview; and suicide plans communicated during an interview. With high cut-off scores the specificity of the SSRS became satisfactory, but the sensitivity dropped below 32%. Internal consistency of the anamnestic history of the SSRS was low, which suggests that anamnestic risk factors for suicide in schizophrenia are multifactorial. Internal consistency of the interview-based items was high, and present state risk factors seemed to consist of two separate factors, depression-anxiety and irritability.

CONCLUSIONS

The SSRS may be clinically useful in identifying schizophrenic patients with a particularly high risk for suicide. However, the SSRS seems not to be a practical screening instrument for suicide risk in schizophrenia, and it is probably impossible to construct a suicide risk scale with both high sensitivity and high specificity in this disorder.

Northern epilepsy syndrome (NES, CLN8)--MRI and electrophysiological studies

Northern epilepsy syndrome (NES, EPMR, progressive epilepsy with mental retardation, CLN8), an inherited childhood-onset epilepsy with mental retardation, has been recently characterized to belong to the family of neuronal ceroid lipofuscinoses (NCLs). In this study, four patients (ages 26-44 years) with NES and eight healthy controls underwent magnetic resonance imaging (MRI) and electrophysiological evaluation with somatosensory evoked magnetic field (SEF) studies. The findings in NES were compared with the known findings in juvenile NCL (JNCL, CLN3) and Finnish variant late infantile NCL (vLINCLFIN, CLN5) that manifest around the same age as NES. Also postmortem MRI was performed on one brain. On the MRIs, slight to moderate cerebellar atrophy was seen in all patients, whereas only two patients had slightly enlarged cerebral sulci. None of the MRIs demonstrated signal intensity abnormalities that are commonly seen in JNCL and vLINCLFIN and are considered to reflect the Wallerian degeneration after neuronal death. Generally SEFs in NES were within normal limits, indicating that the disease had not impaired the function of the neurons on the somatosensory pathway. In conclusion, MRI imaging and SEF findings suggest that the cerebral neuronal death and dysfunction in NES are minimal compared with JNCL and vLINCLFIN.